MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Current Opinion in Cell Biology' source. Tue, 07 Feb 2012 08:48:56 +0100 http://www.medworm.com/index.php?rid=5659168&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22301436%26dopt%3DAbstract Authors: Ranga A, Lutolf MP Abstract The complexity of stem cell niches poses a tremendous challenge to understanding mechanisms of extrinsic regulation of stem cell fate. In order to better understand niche signaling and its effect on stem cell fate choices, in vitro systems are being engineered which recapitulate, in a simplistic but increasingly sophisticated manner, native stem cell niches. New technologies or new combinations of existing technologies allow more systematic ways to probe niche signaling in high-throughput. Systems biology approaches in experimental design, data acquisition and analysis will be necessary to tackle the challenges that lie ahead. PMID: 22301436 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5659168 Tue, 31 Jan 2012 05:00:00 +0100 5659168 http://www.medworm.com/index.php?rid=5659170&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22296770%26dopt%3DAbstract Authors: Resende LP, Jones DL Abstract Tissue stem cells are found in specialized microenvironments (niches) where they are exposed to diverse systemic and local signals that are integrated with cell intrinsic factors to regulate stem cell behavior. In general, systemic signals are utilized to coordinate the response of tissues to acute or long-term changes that affect the whole organism, such as variations in nutrient availability or aging. In contrast, local signaling regulates tissue maintenance by balancing stem cell self-renewal with differentiation under homeostatic conditions and in response to local damage. In this review, we highlight the role of the JAK-STAT pathway in two Drosophila stem cell systems, the testis and intestine, and compare and contrast how activation of t... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5659170 Mon, 30 Jan 2012 05:00:00 +0100 5659170 http://www.medworm.com/index.php?rid=5659169&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22296771%26dopt%3DAbstract Authors: Lee KE, Simon MC Abstract Hypoxia, a condition of insufficient oxygen availability, occurs during normal development as well as tumorigenesis. Cellular responses to hypoxia are primarily mediated by hypoxia-inducible factors (HIFs). Recent studies have revealed that dormant hematopoietic stem cells (HSCs) reside within hypoxic regions of the bone marrow and that HIF is a critical player in HSC homeostasis. The functional significance of HIF in maintaining stemness also applies to cancer stem cells in hematological malignancies. These findings indicate that better understanding of the mechanisms underlying HIF functions in stem cells should permit the development of new therapies for tissue regeneration and cancer. PMID: 22296771 [PubMed - as supplied by publisher] (Sou... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5659169 Mon, 30 Jan 2012 05:00:00 +0100 5659169 http://www.medworm.com/index.php?rid=5659171&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22285930%26dopt%3DAbstract Authors: Hirokawa N, Tanaka Y, Okada Y Abstract The establishment of left-right asymmetry during development of vertebrate embryos depends on leftward flow in the nodal cavity. The flow is produced by the rotational movement of the posteriorly tilted nodal cilia. However, it remains poorly understood how the nodal cilia are tilted posteriorly, and how the directionality of the flow is translated into gene expression patterns in the embryo. Recent studies have identified signaling molecules involved in these processes. First, planar cell polarity signaling has been shown to be involved in the posterior positioning of the basal bodies of nodal cilia, which leads to the posterior tilting of their rotation axes. Second, identification of putative receptors and signaling molecules sugge... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5659171 Fri, 27 Jan 2012 05:00:00 +0100 5659171 http://www.medworm.com/index.php?rid=5659172&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22284347%26dopt%3DAbstract Authors: Hughes-Alford SK, Lauffenburger DA Abstract Chemotaxis of tumor cells in response to a gradient of extracellular ligand is an important step in cancer metastasis. The heterogeneity of chemotactic responses in cancer has not been widely addressed by experimental or mathematical modeling techniques. However, recent advancements in chemoattractant presentation, fluorescent-based signaling probes, and phenotypic analysis paradigms provide rich sources for building data-driven relational models that describe tumor cell chemotaxis in response to a wide variety of stimuli. Here we present gradient sensing, and the resulting chemotactic behavior, in a 'cue-signal-response' framework and suggest methods for utilizing recently reported experimental methods in data-driven modeling ve... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5659172 Wed, 25 Jan 2012 05:00:00 +0100 5659172 http://www.medworm.com/index.php?rid=5659173&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22278045%26dopt%3DAbstract Authors: Marchand V, Gaspar I, Ephrussi A Abstract Initially assumed to be a special feature of highly polarized eukaryotic cells, recent evidence suggests that mRNA localization coupled with local translation is a widespread strategy for spatial restriction of protein synthesis within cells. Genome-wide analyses and live imaging approaches have shed new light on the prevalence and the mechanistic details of this phenomenon. Here we review some of the recent findings that have emerged from research from the RNA localization field, from the birth of mRNAs in the nucleus, to their delivery at specific sites within the cytoplasm. PMID: 22278045 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5659173 Mon, 23 Jan 2012 05:00:00 +0100 5659173 http://www.medworm.com/index.php?rid=5623427&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22257639%26dopt%3DAbstract Authors: Baena-Lopez LA, Nojima H, Vincent JP Abstract The need to coordinate patterning and growth has been appreciated for many years. The logic that enables seamless integration of the relevant inputs is beginning to be elucidated, particularly in wing imaginal discs of Drosophila. In this tissue, multiple regulatory layers involving the two morphogens Wingless and Dpp, the wing-specific determinant, Vestigial, and the Hippo pathway, converge to regulate growth. Intricate cross-regulation between these components may explain why, at the local level, there is no direct correlation between growth and the graded signalling activity of Wingless and Dpp, despite the requirement of these two pathways for growth. PMID: 22257639 [PubMed - as supplied by publisher] (Source: Current O... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5623427 Mon, 16 Jan 2012 05:00:00 +0100 5623427 http://www.medworm.com/index.php?rid=5602626&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22245706%26dopt%3DAbstract Authors: Mahen R, Venkitaraman AR Abstract A striking but poorly explained feature of cell division is the ability to assemble and maintain organelles not bounded by membranes, from freely diffusing components in the cytosol. This process is driven by information transfer across biological scales such that interactions at the molecular scale allow pattern formation at the scale of the organelle. One important example of such an organelle is the centrosome, which is the main microtubule organising centre in the cell. Centrosomes consist of two centrioles surrounded by a cloud of proteins termed the pericentriolar material (PCM). Profound structural and proteomic transitions occur in the centrosome during specific cell cycle stages, underlying events such as centrosome maturation dur... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5602626 Fri, 13 Jan 2012 05:00:00 +0100 5602626 http://www.medworm.com/index.php?rid=5602627&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22244612%26dopt%3DAbstract Authors: Bilokapic S, Schwartz TU Abstract Nuclear pore complexes (NPCs) perforate the double-layered nuclear envelope and form the main gateway for molecular exchange between nucleus and cytoplasm of the eukaryotic cell. Because NPCs are extraordinarily complex and large, thus challenging to investigate on a molecular level, they are still rather poorly understood, despite their pivotal role in cellular homeostasis. To decipher the NPC structure at high resolution, the prerequisite to fully understand its function, a tailored approach is necessary that feeds from complimentary data, obtained at largely different spatial resolutions. The problem is further complicated by the dynamic nature of the NPC, manifested in flexible regions and dynamic components. Here we summarize the curr... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5602627 Wed, 11 Jan 2012 05:00:00 +0100 5602627 http://www.medworm.com/index.php?rid=5578604&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22227227%26dopt%3DAbstract Authors: Furuta K, Lichtenberger R, Helariutta Y Abstract In animals and plants, small RNAs have been identified as important regulatory factors controlling cell fate. A bidirectional cell-to-cell communication involving the mobile transcription factor SHR and microRNA165/166 species specifies the radial position of two types of xylem vessels in Arabidopsis roots. The microRNAs provide short-range non-cell-autonomous developmental signals that are transported through the plasmodesmata (PD) via the symplastic pathway. 21-24 nucleotide-long small RNA species have been shown to move from the shoot to the root. In this review, we highlight the presence of small RNA species as an emerging class of important mobile signals associated with the growth and development of the root. PMID:... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5578604 Thu, 05 Jan 2012 05:00:00 +0100 5578604 http://www.medworm.com/index.php?rid=5578603&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22227228%26dopt%3DAbstract Authors: Cardoso MC, Schneider K, Martin RM, Leonhardt H Abstract The nucleus contains a plethora of different dynamic structures involved in the regulation and catalysis of nucleic acid metabolism and function. Over the past decades countless factors, molecular structures, interactions and posttranslational modifications have been described in this context. On the one side of the size scale X-ray crystallography delivers static snapshots of biomolecules at atomic resolution and on the other side light microscopy allows insights into complex structures of living cells and tissues in real time but poor resolution. Recent advances in light and electron microscopy are starting to close the temporal and spatial resolution gap from the atomic up to the cellular level. Old challenges and... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5578603 Thu, 05 Jan 2012 05:00:00 +0100 5578603 http://www.medworm.com/index.php?rid=5578605&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22226236%26dopt%3DAbstract Authors: Drummond IA Abstract Recent advances in developmental genetics and human disease gene cloning have highlighted the essential roles played by cilia in developmental cell fate decisions, left-right asymmetry, and the pathology of human congenital disorders. Hedgehog signaling in sensory cilia illustrates the importance of trafficking receptors to the cilia membrane (Patched and Smoothened) and the concept of cilia 'gatekeepers' that restrict entry and egress of cilia proteins (Suppressor of fused: Gli complexes). Cilia-driven fluid flow in the embryonic node highlights the role of motile cilia in both generation and detection of mechanical signals in development. In this brief review I select examples of recent studies that have clarified and consolidated our understanding o... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5578605 Wed, 04 Jan 2012 05:00:00 +0100 5578605 http://www.medworm.com/index.php?rid=5578606&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22221609%26dopt%3DAbstract Authors: O'Connell CB, Khodjakov A, McEwen BF Abstract Kinetochores are complex macromolecular assemblies that link chromosomes to the mitotic spindle, mediate forces for chromosome motion, and generate the checkpoint signal delaying anaphase onset until all chromosomes are incorporated into the spindle. Proper execution of these functions depends on precise interactions between kinetochores and microtubules. While the molecular composition of the kinetochore is well described, structural organization of this organelle at the molecular and atomic levels is just beginning to emerge. Recent structural studies across scales suggest that kinetochores should not be viewed as rigid static scaffolds. Instead, these organelles exhibit a surprising degree of flexibility that enables rapid a... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5578606 Tue, 03 Jan 2012 05:00:00 +0100 5578606 http://www.medworm.com/index.php?rid=5560725&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22209238%26dopt%3DAbstract Authors: Bravo-Cordero JJ, Hodgson L, Condeelis J Abstract Metastasis requires tumor cell dissemination to different organs from the primary tumor. Dissemination is a complex cell motility phenomenon that requires the molecular coordination of the protrusion, chemotaxis, invasion and contractility activities of tumor cells to achieve directed cell migration. Recent studies of the spatial and temporal activities of the small GTPases have begun to elucidate how this coordination is achieved. The direct visualization of the pathways involved in actin polymerization, invasion and directed migration in dissemination competent tumor cells will help identify the molecular basis of dissemination and allow the design and testing of more specific and selective drugs to block metastasis. ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5560725 Fri, 30 Dec 2011 05:00:00 +0100 5560725 http://www.medworm.com/index.php?rid=5560724&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22209239%26dopt%3DAbstract Authors: Kanchanawong P, Waterman CM Abstract Visualization methods are key to gaining insights into cellular structure and function. Since diffraction has long confined optical microscopes to a resolution no better than hundreds of nanometers, the observation of ultrastructural features has traditionally been the domain of electron microscopes (EM). In the past decade, however, advances in super-resolution fluorescence microscopy have considerably expanded the capability of light-based imaging techniques. Advantages of fluorescent labeling such as high sensitivity, specificity, and multichannel capability, can now be exploited to dissect ultrastructural features of cells. With recent methods capable of imaging specific proteins with a resolution on the order of a few tens of nanom... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5560724 Fri, 30 Dec 2011 05:00:00 +0100 5560724 http://www.medworm.com/index.php?rid=5560723&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22209728%26dopt%3DAbstract Authors: Skopelitis DS, Husbands AY, Timmermans MC Abstract RNA interference (RNAi) in plants has long been known to produce a non-cell autonomous signal capable of silencing target genes over great cellular distances. However, only recently have RNAi-derived small RNAs been formally shown to comprise that mobile signal. Interestingly, some of these mobile small RNAs play critical roles in plant development, forming gradients that regulate the activity of their targets in a dosage-dependent manner. These properties resemble features of morphogens in animals, leading us to postulate that such cell-fate-defining small RNAs employ similar principles for the generation, stabilization and interpretation of their expression gradients. Here we review our understanding of small RNA mobilit... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5560723 Thu, 29 Dec 2011 05:00:00 +0100 5560723 http://www.medworm.com/index.php?rid=5560722&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22209729%26dopt%3DAbstract Authors: Dorn JF, Maddox PS Abstract Protein dynamics generate adaptive cellular architecture. This concept is exemplified by kinetochores, organelles that orchestrate chromosome segregation during mitosis. In this review, we will focus on protein dynamics at kinetochores and discuss how these dynamics impact chromosome motility during mitosis. PMID: 22209729 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5560722 Thu, 29 Dec 2011 05:00:00 +0100 5560722 http://www.medworm.com/index.php?rid=5550486&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22196929%26dopt%3DAbstract Authors: Hanein D, Horwitz AR Abstract Adhesions between the cell and the extracellular matrix (ECM) are mechanosensitive multi-protein assemblies that transmit force across the cell membrane and regulate biochemical signals in response to the chemical and mechanical environment. These combined functions in force transduction, signaling and mechanosensing contribute to cellular phenotypes that span development, homeostasis and disease. These adhesions form, mature and disassemble in response to actin organization and physical forces that originate from endogenous myosin activity or external forces by the extracellular matrix. Despite advances in our understanding of the protein composition, interactions and regulation, our understanding of matrix adhesion structure and organization... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5550486 Wed, 21 Dec 2011 05:00:00 +0100 5550486 http://www.medworm.com/index.php?rid=5550485&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22196930%26dopt%3DAbstract Authors: Grünwald D, Singer RH Abstract The nuclear pore complex (NPC) has long been viewed as a point-like entry and exit channel between the nucleus and the cytoplasm. New data support a different view whereby the complex displays distinct spatial dynamics of variable duration ranging from milliseconds to events spanning the entire cell cycle. Discrete interaction sites outside the central channel become apparent, and transport regulation at these sites seems to be of greater importance than currently thought. Nuclear pore components are highly active outside the NPC or impact the fate of cargo transport away from the nuclear pore. The NPC is a highly dynamic, crowded environment-constantly loaded with cargo while providing selectivity based on unfolded proteins. Taken together,... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5550485 Wed, 21 Dec 2011 05:00:00 +0100 5550485 http://www.medworm.com/index.php?rid=5550484&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22196931%26dopt%3DAbstract Authors: Bakhoum SF, Compton DA Abstract The essential role of microtubules in cell division has long been known. Yet the mechanism by which microtubule attachment to chromosomes at kinetochores is regulated has only been recently revealed. Here, we review the role of kinetochore-microtubule (kMT) attachment dynamics in the cell cycle as well as emerging evidence linking deregulation of kMT attachments to diseases where chromosome mis-segregation and aneuploidy play a central role. Evidence indicates that the dynamic behavior of kMTs must fall within narrow permissible boundaries, which simultaneously allow a level of stability sufficient to establish and maintain chromosome-microtubule attachments and a degree of instability that permits error correction required for accurate chro... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5550484 Wed, 21 Dec 2011 05:00:00 +0100 5550484 http://www.medworm.com/index.php?rid=5550483&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22196932%26dopt%3DAbstract Authors: Inui M, Montagner M, Piccolo S Abstract Morphogens induce biological diversity by operating in a dose-dependent manner. Here we review recent evidences indicating that microRNAs (miRNAs) are ideally suited to serve the morphogen cause. miRNAs regulate the establishment of morphogen gradients, including TGFβ, Wnt and other growth factors by acting on their secretion, distribution and clearance. miRNA are also critical in receiving cells, establishing context-dependency and threshold responses. Moreover, miRNAs contributes to gene networks that transform the graded activity of a morphogen into robust cell fate decisions. Finally, we discuss in the perspective section the implication of the new ceRNA hypothesis for morphogen biology. PMID: 22196932 [PubMed - as supplied ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5550483 Wed, 21 Dec 2011 05:00:00 +0100 5550483 http://www.medworm.com/index.php?rid=5550482&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22196933%26dopt%3DAbstract Authors: Wei C, Wang X, Zheng M, Cheng H Abstract The calcium ion is the simplest and most versatile second messenger in biology. Harboring a myriad of calcium effector proteins, migrating cells display an exquisite multiscaled and multilayered architecture of intracellular calcium dynamics. In motile fibroblasts, for instance, there are transient calcium microdomains ('calcium flickers') of ∼5μm in diameter and 10-2000ms in duration, a rising flicker activity gradient along the rear-to-front axis, and a shallow background calcium concentration gradient in the opposite direction. When subjected to external gradients of guidance cues, local flicker gradients are created de novo in the leading edge, which steer cells to turn in new directions as defined by the asymmetry of the fli... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5550482 Wed, 21 Dec 2011 05:00:00 +0100 5550482 http://www.medworm.com/index.php?rid=5550487&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22192274%26dopt%3DAbstract Authors: Shimi T, Butin-Israeli V, Goldman RD Abstract Recent studies of the nuclear envelope (NE) have emphasized its role in linking the nuclear and cytoplasmic compartments of mammalian cells. The inner face of the NE is bound to chromatin and this interaction is involved in regulating DNA replication and transcription. The outer face of the NE binds to different components of the cytoskeleton, and these interactions are involved in nuclear positioning. Many disease causing mutations in genes encoding NE proteins cause significant changes in nuclear architecture and cytoskeletal interactions with the NE. These mutations are also providing important new insights into nuclear-cytoplasmic interactions. PMID: 22192274 [PubMed - as supplied by publisher] (Source: Current Opinion ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5550487 Tue, 20 Dec 2011 05:00:00 +0100 5550487 http://www.medworm.com/index.php?rid=5535534&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22172408%26dopt%3DAbstract Authors: Barone V, Heisenberg CP Abstract Visualizing and analyzing shape changes at various scales, ranging from single molecules to whole organisms, are essential for understanding complex morphogenetic processes, such as early embryonic development. Embryo morphogenesis relies on the interplay between different tissues, the properties of which are again determined by the interaction between their constituent cells. Cell interactions, on the other hand, are controlled by various molecules, such as signaling and adhesion molecules, which in order to exert their functions need to be spatiotemporally organized within and between the interacting cells. In this review, we will focus on the role of cell adhesion functioning at different scales to organize cell, tissue and embryo morpho... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5535534 Tue, 13 Dec 2011 05:00:00 +0100 5535534 http://www.medworm.com/index.php?rid=5535535&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22169676%26dopt%3DAbstract Authors: Towers M, Wolpert L, Tickle C Abstract The developing limb is one of the first systems where it was proposed that a signalling gradient is involved in pattern formation. This gradient for specifying positional information across the antero-posterior axis is based on Sonic hedgehog signalling from the polarizing region. Recent evidence suggests that Sonic hedgehog signalling also specifies positional information across the antero-posterior axis by a timing mechanism acting in parallel with graded signalling. The progress zone model for specifying proximo-distal pattern, involving timing to provide cells with positional information, continues to be challenged, and there is further evidence that graded signalling by retinoic acid specifies the proximal part of the limb. Other... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5535535 Mon, 12 Dec 2011 05:00:00 +0100 5535535 http://www.medworm.com/index.php?rid=5535538&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22154943%26dopt%3DAbstract Authors: Iglesias PA, Devreotes PN Abstract The actin cytoskeleton in motile cells has many of the hallmarks of an excitable medium, including the presence of propagating waves. This excitable behavior can account for the spontaneous migration of cells. A number of reports have suggested that the chemoattractant-mediated signaling can bias excitability, thus providing a means by which cell motility can be directed. In this review, we discuss some of these observations and theories proposed to explain them. We also suggest a mechanism for cell polarity that can be incorporated into the existing framework. PMID: 22154943 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5535538 Fri, 09 Dec 2011 05:00:00 +0100 5535538 http://www.medworm.com/index.php?rid=5535537&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22154944%26dopt%3DAbstract Authors: Deluca JG, Musacchio A Abstract Successful mitosis depends on the stable, yet regulated attachment of chromosomes to spindle microtubules. The kinetochore, a large macromolecular structure assembled at sites of centromeric heterochromatin, is responsible for generating and regulating these essential attachments. Over the last several years, concerted experimental efforts have brought the structural view of the kinetochore-microtubule interface more clearly into focus. Here, we review important recent advancements and discuss several unresolved questions regarding how kinetochores dynamically bridge mitotic chromosomes to spindle microtubules. PMID: 22154944 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5535537 Fri, 09 Dec 2011 05:00:00 +0100 5535537 http://www.medworm.com/index.php?rid=5535536&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22169400%26dopt%3DAbstract Authors: Sourjik V, Wingreen NS Abstract Chemotaxis allows bacteria to follow gradients of nutrients and other environmental stimuli. The bacterium Escherichia coli performs chemotaxis via a run-and-tumble strategy in which sensitive temporal comparisons lead to a biased random walk, with longer runs in the preferred gradient direction. The chemotaxis network of E. coli has developed over the years into one of the most thoroughly studied model systems for signal transduction and behavior, yielding general insights into such properties of cellular networks as signal amplification, signal integration, and robustness. Despite its relative simplicity, the operation of the E. coli chemotaxis network is highly refined and evolutionarily optimized at many levels. For example, recent studi... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5535536 Thu, 08 Dec 2011 05:00:00 +0100 5535536 http://www.medworm.com/index.php?rid=5535540&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22152945%26dopt%3DAbstract Authors: Raftery LA, Umulis DM Abstract Bone morphogenetic protein (BMP) signaling controls development and maintenance of many tissues. Genetic and quantitative approaches in Drosophila reveal that ligand isoforms show distinct function in wing development. Spatiotemporal control of BMP patterning depends on a network of extracellular proteins Pent, Ltl and Dally that regulate BMP signaling strength and morphogen range. BMP-mediated feedback regulation of Pent, Ltl, and Dally expression provides a system where cells actively respond to, and modify, the extracellular morphogen landscape to form a gradient that exhibits remarkable properties, including proportional scaling of BMP patterning with tissue size and the modulation of uniform tissue growth. This system provides valuable i... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5535540 Mon, 05 Dec 2011 05:00:00 +0100 5535540 http://www.medworm.com/index.php?rid=5535539&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22152946%26dopt%3DAbstract This article summarizes some recent advances in this field. PMID: 22152946 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5535539 Mon, 05 Dec 2011 05:00:00 +0100 5535539 http://www.medworm.com/index.php?rid=5475558&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22138388%26dopt%3DAbstract Authors: Wehrle-Haller B Abstract Integrin-dependent cell adhesions come in different shapes and serve in different cell types for tasks ranging from cell-adhesion, migration, and the remodeling of the extracellular matrix to the formation and stabilization of immunological and chemical synapses. A major challenge consists in the identification of adhesion-specific as well as common regulatory mechanisms, motivating the need for a deeper analysis of protein-protein interactions in the context of intact focal adhesions. Specifically, it is critical to understand how small differences in binding of integrins to extracellular ligands and/or cytoplasmic adapter proteins affect the assembly and function of an entire focal adhesion. By using the talin-integrin pair as a starting point, I... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5475558 Fri, 02 Dec 2011 05:00:00 +0100 5475558 http://www.medworm.com/index.php?rid=5475559&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22129583%26dopt%3DAbstract Authors: Springer TA, Dustin ML Abstract Integrins dynamically equilibrate between three conformational states on cell surfaces. A bent conformation has a closed headpiece. Two extended conformations contain either a closed or an open headpiece. Headpiece opening involves hybrid domain swing-out and a 70 Å separation at the integrin knees, which is conveyed by allostery from the hybrid-proximal end of the βI domain to a 3 Å rearrangement of the ligand-binding site at the opposite end of the βI domain. Both bent-closed and extended-closed integrins have low affinity, whereas extended-open integrin affinity is 10(3) to 10(4) higher. Integrin-mediated adhesion requires the extended-open conformation, which in physiological contexts is stabilized by post-ligand binding events. Inte... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5475559 Mon, 28 Nov 2011 05:00:00 +0100 5475559 http://www.medworm.com/index.php?rid=5421795&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22079175%26dopt%3DAbstract Authors: Hampoelz B, Lecuit T Abstract The nucleus is by far one of the stiffest organelles within cells of higher eukaryotes. Its mechanical properties are determined by contributions from the nuclear lamina and chromatin. Together they allow a viscoelastic response of the nucleus to applied stresses, where the lamina is thought to behave as an elastic shell, while the nucleoplasm contributes as a largely viscous material. Nuclear mechanics changes during differentiation and development. Altered nuclear mechanics reflects but might also influence global re-arrangements in chromatin architecture, which take place when cells commit themselves into distinct lineages. Thus it is likely that the mechanical characteristics of nuclei significantly contribute to proper differentiation. ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5421795 Fri, 11 Nov 2011 05:00:00 +0100 5421795 http://www.medworm.com/index.php?rid=5380237&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22051380%26dopt%3DAbstract Authors: Wacker A, Gerhardt H Abstract Blood vessel development is a vital process during embryonic development, during tissue growth, regeneration and disease processes in the adult. In the past decade researchers have begun to unravel basic molecular mechanisms that regulate the formation of vascular lumen, sprouting angiogenesis, fusion of vessels, and pruning of the vascular plexus. The understanding of the biology of these angiogenic processes is increasingly driven through studies on vascular development at the cellular resolution. Single cell analysis in vivo, advanced genetic tools and the widespread use of powerful animal models combined with improved imaging possibilities are delivering new insights into endothelial cell form, function and behavior angiogenesis. Moreover,... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5380237 Tue, 01 Nov 2011 04:00:00 +0100 5380237 http://www.medworm.com/index.php?rid=5380238&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22040653%26dopt%3DAbstract Authors: Castanon I, González-Gaitán M PMID: 22040653 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5380238 Sat, 29 Oct 2011 04:00:00 +0100 5380238 http://www.medworm.com/index.php?rid=5361427&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22018538%26dopt%3DAbstract Authors: Hall MN PMID: 22018538 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5361427 Wed, 19 Oct 2011 04:00:00 +0100 5361427 http://www.medworm.com/index.php?rid=5329376&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22000622%26dopt%3DAbstract Authors: Castanon I, González-Gaitán M Abstract Tissue morphogenesis depends on the spatial arrangement of cells during development. A number of mechanisms have been described to contribute to the final shape of a tissue or organ, ranging from cell intercalation to the response of cells to chemotactic cues. One such mechanism is oriented cell division. Oriented cell division is determined by the position of the mitotic spindle. Indeed, there is increasing evidence implicating spindle misorientation in tissue and organ misshaping, which underlies disease conditions such as tumorigenesis or polycystic kidneys. Here we review recent studies addressing how the direction of tissue growth is determined by the orientation of cell division and how both extrinsic and intrinsic cues contro... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5329376 Thu, 13 Oct 2011 04:00:00 +0100 5329376 http://www.medworm.com/index.php?rid=5329377&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21996102%26dopt%3DAbstract Authors: Banasr M, Dwyer JM, Duman RS Abstract Depression is associated with structural alterations in limbic brain regions that control emotion and mood. Studies of chronic stress in animal models and postmortem tissue from depressed subjects demonstrate that these structural alterations result from atrophy and loss of neurons and glial cells. These findings indicate that depression and stress-related mood disorders can be considered mild neurodegenerative disorders. Importantly, there is evidence that these structural alterations can be blocked or even reversed by elimination of stress and by antidepressant treatments. A major focus of current investigations is to characterize the molecular signaling pathways and factors that underlie these effects of stress, depression, and anti... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5329377 Tue, 11 Oct 2011 04:00:00 +0100 5329377 http://www.medworm.com/index.php?rid=5329378&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21982544%26dopt%3DAbstract Authors: Martinez Arias A, Brickman JM Abstract Stem and progenitor cells are populations of cells that retain the capacity to populate specific lineages and to transit this capacity through cell division. However, attempts to define markers for stem cells have met with limited success. Here we consider whether this limited success reflects an intrinsic requirement for heterogeneity with stem cell populations. We focus on Embryonic Stem (ES) cells, in vitro derived cell lines from the early embryo that are considered both pluripotent (able to generate all the lineages of the future embryo) and indefinitely self renewing. We examine the relevance of recently reported heterogeneities in ES cells and whether these heterogeneities themselves are inherent requirements of functional pote... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5329378 Wed, 05 Oct 2011 04:00:00 +0100 5329378 http://www.medworm.com/index.php?rid=5298162&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21962973%26dopt%3DAbstract Authors: Dettmer J, Friml J Abstract In unicellular and multicellular organisms, cell polarity is essential for a wide range of biological processes. An important feature of cell polarity is the asymmetric distribution of proteins in or at the plasma membrane. In plants such polar localized proteins play various specific roles ranging from organizing cell morphogenesis, asymmetric cell division, pathogen defense, nutrient transport and establishment of hormone gradients for developmental patterning. Moreover, flexible respecification of cell polarities enables plants to adjust their physiology and development to environmental changes. Having evolved multicellularity independently and lacking major cell polarity mechanisms of animal cells, plants came up with alternative solutions t... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5298162 Thu, 29 Sep 2011 04:00:00 +0100 5298162 http://www.medworm.com/index.php?rid=5298161&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21963299%26dopt%3DAbstract Authors: Dazert E, Hall MN Abstract The target of rapamycin (TOR) is a highly conserved serine/threonine kinase and a central controller of cell growth, metabolism and aging. Mammalian TOR (mTOR) is activated in response to nutrients, growth factors and cellular energy. Dysregulated mTOR signaling has been implicated in major disease. Here we review recent findings on the role of mTOR in cancer, metabolic disorders, neurological diseases, and inflammation. PMID: 21963299 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5298161 Thu, 29 Sep 2011 04:00:00 +0100 5298161 http://www.medworm.com/index.php?rid=5298160&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21963300%26dopt%3DAbstract Authors: Suter DM, Molina N, Naef F, Schibler U Abstract In both prokaryotes and eukaryotes, transcription has been described as being temporally discontinuous, most genes being active mainly during short activity windows interspersed by silent periods. In mammalian cells, recent studies performed at the single cell level have revealed that transcriptional kinetics are highly gene-specific and constrained by the presence of refractory periods of inactivity before a gene can be turned on again. While the underlying mechanisms generating gene-specific kinetic characteristics remain unclear, various biological consequences of transcriptional discontinuity have been unravelled during the past few years. Here we review recent advances on understanding transcriptional kinetics of individ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5298160 Thu, 29 Sep 2011 04:00:00 +0100 5298160 http://www.medworm.com/index.php?rid=5298159&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21963301%26dopt%3DAbstract Authors: Barad O, Hornstein E, Barkai N Abstract The patterning of multicellular organisms is robust to environmental, genetic, or stochastic fluctuations. Mathematical modeling is instrumental in identifying mechanisms supporting this robustness. The principle of lateral inhibition, whereby a differentiating cell inhibits its neighbors from adopting the same fate, is frequently used for selecting a single cell out of a cluster of equipotent cells. For example, Sensory Organ Precursors (SOP) in the fruit-fly Drosophila implement lateral inhibition by activating the Notch-Delta pathway. We discuss parameters affecting the rate of errors in this process, and the mechanism (inhibitory cis interaction between Notch and Delta) predicted to reduce this error. PMID: 21963301 [PubMed -... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5298159 Thu, 29 Sep 2011 04:00:00 +0100 5298159 http://www.medworm.com/index.php?rid=5247388&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21937209%26dopt%3DAbstract Authors: Lecuit T, Sonnenberg A PMID: 21937209 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5247388 Mon, 19 Sep 2011 04:00:00 +0100 5247388 http://www.medworm.com/index.php?rid=5247389&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21930368%26dopt%3DAbstract Authors: Spéder P, Liu J, Brand AH Abstract The physiological status of an organism is able to influence stem cell behaviour to ensure that stem cells meet the needs of the organism during growth, and in response to injury and environmental changes. In particular, the brain is sensitive to metabolic fluctuations. Here we discuss how nutritional status is able to regulate systemic and local insulin/IGF signalling so as to control aspects of neural stem behaviour. Recent results have begun to reveal how systemic signals are relayed to neural stem cells through local interactions with a glial niche. Although much still remains to be discovered, emerging parallels between the regulation of Drosophila and mammalian stem cells suggest a conserved mechanism for how the brain responds to ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5247389 Sat, 17 Sep 2011 04:00:00 +0100 5247389 http://www.medworm.com/index.php?rid=5247390&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21925855%26dopt%3DAbstract Authors: Araki K, Ellebedy AH, Ahmed R Abstract The target of rapamycin (TOR) is a crucial intracellular regulator of the immune system. Recent studies have suggested that immunosuppression by TOR inhibition may be mediated by modulating differentiation of both effector and regulatory CD4 T cell subsets. However, it was paradoxically shown that inhibiting TOR signaling has immunostimulatory effects on the generation of long-lived memory CD8 T cells. Beneficial effects of TOR inhibition have also been observed with dendritic cells and hematopoietic stem cells. This immune modulation may contribute to lifespan extension seen in mice with mTOR inhibition. Here, we review recent findings on TOR modulation of innate and adaptive immune responses, and discuss potential applications of re... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5247390 Fri, 16 Sep 2011 04:00:00 +0100 5247390 http://www.medworm.com/index.php?rid=5247391&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21924601%26dopt%3DAbstract Authors: Margadant C, Monsuur HN, Norman JC, Sonnenberg A Abstract Integrin adhesion receptors are essential for the normal function of most multicellular organisms, and defective integrin activation or integrin signaling is associated with an array of pathological conditions. Integrins are regulated by conformational changes, clustering, and trafficking, and regulatory mechanisms differ strongly between individual integrins and between cell types. Whereas integrins in circulating blood cells are activated by an inside-out-induced conformational change that favors high-affinity ligand binding, β1-integrins in adherent cells can be activated by force or clustering. In addition, endocytosis and recycling play an important role in the regulation of integrin turnover and integrin redi... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5247391 Wed, 14 Sep 2011 04:00:00 +0100 5247391 http://www.medworm.com/index.php?rid=5219282&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21890337%26dopt%3DAbstract Authors: Leckband DE, le Duc Q, Wang N, de Rooij J Abstract Cell-to-cell junctions are crucial mechanical and signaling hubs that connect cells within tissues and probe the mechanics of the surrounding environment. Although the capacity of cell-to-extracellular-matrix (ECM) adhesions to sense matrix mechanics and proportionally modify cell functions is well established, cell-cell adhesions only recently emerged as a new class of force sensors. This finding exposes new pathways through which force can instruct cell functions. This review highlights recent findings, which demonstrate that protein complexes associated with classical cadherins, the principal architectural proteins at cell-cell junctions in all soft tissues, are mechanosensors. We further discuss the current understandi... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5219282 Fri, 02 Sep 2011 04:00:00 +0100 5219282 http://www.medworm.com/index.php?rid=5193084&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21885270%26dopt%3DAbstract Authors: Luxton GG, Gundersen GG Abstract A hallmark of polarity in most migrating cells is the orientation of the nuclear centrosomal (NC) axis relative to the front-back cellular axis. Here, we review 'effector functions' associated with the NC axis during cell migration. We highlight recent research that has demonstrated that the orientation of the NC axis depends upon the coordinated, but separate positioning of the nucleus and the centrosome. We stress the importance of environmental factors such as cell-cell contacts and substrate topology for NC axis orientation. Finally, we summarize tests of the significance of this axis for cell migration and disease. PMID: 21885270 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5193084 Mon, 29 Aug 2011 23:00:00 +0100 5193084 http://www.medworm.com/index.php?rid=5193085&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21880478%26dopt%3DAbstract Authors: Iglesias-Bartolome R, Gutkind JS Abstract The integration of extrinsic and intrinsic signals is required to preserve the self-renewal and tissue regenerative capacity of adult stem cells, while protecting them from malignant conversion or loss of proliferative potential by death, differentiation or senescence. Here we review emerging signaling circuitries regulating stem cell fate, with emphasis on epithelial stem cells. Wnt, mTOR, GPCRs, Notch, Rho GTPases, YAP and DNA and histone methylases are some of the mechanisms that allow stem cells to balance their regenerative potential and the initiation of terminal differentiation programs, guaranteeing appropriate tissue homeostasis. Understanding the signaling circuitries regulating stem cell fate decisions might provide impo... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5193085 Sun, 28 Aug 2011 23:00:00 +0100 5193085 http://www.medworm.com/index.php?rid=5141668&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21835601%26dopt%3DAbstract Authors: Alic N, Partridge L Abstract Reduction in nutrient intake without malnutrition can delay ageing and extend healthy life in diverse organisms from yeast to primates. This effect can be recapitulated by genetic or pharmacological dampening of the signal through nutrient signalling pathways, making them a promising target for intervention into human ageing and age-related diseases. Here we review the current knowledge of the interactions between nutrient signalling pathways and ageing, focusing on the findings emerged in the past few years. PMID: 21835601 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5141668 Mon, 08 Aug 2011 23:00:00 +0100 5141668 http://www.medworm.com/index.php?rid=5104180&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21807488%26dopt%3DAbstract Authors: St Johnston D, Sanson B The adult form of a multicellular organism is shaped by a series of morphogenetic processes that organise the body into tissues and organs. Most of these events involve the deformation of sheets of epithelial cells that are highly polarised along their apical-basal axes and attached to each other by lateral junctions. Here we discuss the role played by modifications in the apical-basal polarity system in driving morphogenesis, with an emphasis on well-characterised events during Drosophila development. Changing the activity of polarity factors can alter the relative sizes of the apical, lateral and basal domains. This can drive transitions between cuboidal, columnar and squamous epithelial morphologies, to increase or decrease the surface area of an epi... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5104180 Fri, 29 Jul 2011 23:00:00 +0100 5104180 http://www.medworm.com/index.php?rid=5104179&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21807489%26dopt%3DAbstract Authors: Rodríguez-Fraticelli AE, Gálvez-Santisteban M, Martín-Belmonte F Epithelial organs are generated from groups of non-polarized cells by a combination of processes that induce the acquisition of cell polarity, lumen formation, and the subsequent steps required for tubulogenesis. The subcellular mechanisms associated to these processes are still poorly understood. The extracellular environment provides a cue for the initial polarization, while cytoskeletal rearrangements build up the three-dimensional architecture that supports the central lumen. The proper orientation of cell division in the epithelium has been found to be required for the normal formation of the central lumen in epithelial morphogenesis. Moreover, recent data in cellular models and in vivo have shed light in... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5104179 Fri, 29 Jul 2011 23:00:00 +0100 5104179 http://www.medworm.com/index.php?rid=5104178&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21807490%26dopt%3DAbstract Authors: Yonemura S The adherens junction (AJ) is a major cell-cell junction that mediates cell recognition, adhesion, morphogenesis, and tissue integrity. Although AJs transmit forces generated by actomyosin from one cell to another, AJs have long been considered as an area where signal transduction from cadherin ligation takes place through cell adhesion. Through the efforts to understand embryonic or cellular morphogenesis, dynamic interactions between the AJ and actin filaments have become crucial issues to be addressed since actin association is essential for AJ development, remodeling and function. Here, I provide an overview of cadherin-actin interaction from morphological aspects and of possible molecular mechanisms revealed by recent studies. PMID: 21807490 [PubMed - as su... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5104178 Fri, 29 Jul 2011 23:00:00 +0100 5104178 http://www.medworm.com/index.php?rid=5104177&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21807491%26dopt%3DAbstract Authors: Maître JL, Heisenberg CP Recent advances in microscopy techniques and biophysical measurements have provided novel insight into the molecular, cellular and biophysical basis of cell adhesion. However, comparably little is known about a core element of cell-cell adhesion-the energy of adhesion at the cell-cell contact. In this review, we discuss approaches to understand the nature and regulation of adhesion energy, and propose strategies to determine adhesion energy between cells in vitro and in vivo. PMID: 21807491 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5104177 Fri, 29 Jul 2011 23:00:00 +0100 5104177 http://www.medworm.com/index.php?rid=5104176&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21807492%26dopt%3DAbstract Authors: Rottner K, Stradal TE Cell migration is a highly coordinated process involving a multitude of separable but intertwined phenomena traditionally studied in multiple cell types, tissues and model systems. In spite of the multitude of mechanisms and modes of motility described in all these different systems, the ability to dynamically reorganize the actin cytoskeleton is common to all of them. However, defining the key molecular players in motility and their precise molecular functions continues to be challenging, last not least owing to robustness and flexibility common to complex biological phenomena. Here we will draft the future steps essential for achieving true progress towards the goal to increase our understanding of actin cytoskeleton dynamics driving cell migration. ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5104176 Fri, 29 Jul 2011 23:00:00 +0100 5104176 http://www.medworm.com/index.php?rid=5058208&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21764278%26dopt%3DAbstract Authors: Gorfinkiel N, Blanchard GB In the past few years, advances in microscopy and quantitative image analysis have lead to a completely new understanding of the processes underlying the cell shape changes and cell rearrangements that drive tissue morphogenesis. In a handful of tissues so far, though the number will surely increase rapidly, it has been shown that cell behaviour is not continuous but proceeds in pulses driven by the contractile activity of dynamic cortical actomyosin networks. The patterns and dynamics of temporary subcellular contractile foci, driven by local increases in actin and myosin, are remarkably similar in disparate tissues. Cells in all tissues display a similar range of intervals between contractions, with increasing frequencies associated with stronger t... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5058208 Fri, 15 Jul 2011 23:00:00 +0100 5058208 http://www.medworm.com/index.php?rid=5009177&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21733666%26dopt%3DAbstract Authors: Nichols B, Nunnari J PMID: 21733666 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5009177 Sun, 03 Jul 2011 23:00:00 +0100 5009177 http://www.medworm.com/index.php?rid=5009178&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21705204%26dopt%3DAbstract Authors: Karbowski M, Youle RJ Mitochondrial outer membrane proteins have been found to be ubiquitinated and degraded by the proteasome. This process shares at least one component of the ERAD pathway of ER membrane protein degradation, the AAA ATPase cdc48/p97/VCP, thought to extract integral membrane proteins from the lipid bilayer and chaperone them to the proteasome. Proteasomal degradation of the outer mitochondrial membrane (OMM) protein Mcl1 regulates apoptosis whereas Parkin-mediated ubiquitination and degradation of Mitofusins can inhibit mitochondrial fusion and promote mitophagy. The breadth of OMM ubiquitin/proteasome substrates and the physiological relevance of their turnover are only beginning to be understood. PMID: 21705204 [PubMed - as supplied by publisher] (Sourc... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=5009178 Thu, 23 Jun 2011 23:00:00 +0100 5009178 http://www.medworm.com/index.php?rid=4962273&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21696935%26dopt%3DAbstract Authors: Scales TM, Parsons M PMID: 21696935 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4962273 Sun, 19 Jun 2011 23:00:00 +0100 4962273 http://www.medworm.com/index.php?rid=4962274&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21689915%26dopt%3DAbstract Authors: Nuttall JM, Motley A, Hettema EH In recent years, it has become evident that peroxisomes form part of the endomembrane system. Peroxisomes can form from the ER via a maturation process and they can multiply by growth and division, whereby the ER provides membrane for growth and ongoing fission (Figure 1). Until very recently, it was widely accepted that most peroxisomal membrane proteins (PMPs) insert directly into peroxisomes, whereas a small subset of PMPs traffic via the ER. In this minireview, we focus mainly on PMP biogenesis, and highlight recent advances in peroxisomal matrix protein import, fission and segregation in yeast. PMID: 21689915 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4962274 Fri, 17 Jun 2011 23:00:00 +0100 4962274 http://www.medworm.com/index.php?rid=4962276&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21665455%26dopt%3DAbstract Authors: Hartman NC, Groves JT Large-scale molecular assemblies, or signaling clusters, at the cell membrane are emerging as important regulators of cell signaling. Here, we review new findings and describe shared characteristics common to signaling clusters from a diverse set of cellular systems. The well-known T cell receptor cluster serves as our paradigmatic model. Specifically, each cluster initiates recruitment of hundreds of molecules to the membrane, interacts with the actin cytoskeleton, and contains a significant fraction of the entire signaling process. Probed by recent advancements in patterning and microscopy techniques, the signaling clusters display functional outcomes that are not readily predictable from the individual components. PMID: 21665455 [PubMed - as suppli... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4962276 Thu, 09 Jun 2011 23:00:00 +0100 4962276 http://www.medworm.com/index.php?rid=4962275&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21665456%26dopt%3DAbstract Authors: Howe AK Calcium (Ca(2+)) and the cAMP-dependent protein kinase (PKA) are pleiotropic cellular regulators and both exert powerful, diverse effects on cytoskeletal dynamics, cell adhesion, and cell migration. Localization, by A-kinase-anchoring proteins (AKAPs), of PKA activity to the protrusive leading edge, integrins, and other regulators of cytoskeletal dynamics has emerged as an important facet of its role in cell migration. Additional recent work has firmly established the importance of Ca(2+) influx through mechanosensitive transient receptor potential (TRP) channels and through store-operated Ca(2+) entry (SOCE) in cell migration. Finally, there is considerable evidence showing that these mechanisms of Ca(2+) influx and PKA regulation intersect-and often interact-and thus... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4962275 Thu, 09 Jun 2011 23:00:00 +0100 4962275 http://www.medworm.com/index.php?rid=4962277&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664808%26dopt%3DAbstract Authors: Brodsky JL, Skach WR The evolution of eukaryotes was accompanied by an increased need for intracellular communication and cellular specialization. Thus, a more complex collection of secreted and membrane proteins had to be synthesized, modified, and folded. The endoplasmic reticulum (ER) thereby became equipped with devoted enzymes and associated factors that both catalyze the production of secreted proteins and remove damaged proteins. A means to modify ER function to accommodate and destroy misfolded proteins also evolved. Not surprisingly, a growing number of human diseases are linked to various facets of ER function. Each of these topics will be discussed in this article, with an emphasis on recent reports in the literature that employed diverse models. PMID: 21664808 ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4962277 Wed, 08 Jun 2011 23:00:00 +0100 4962277 http://www.medworm.com/index.php?rid=4912700&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21641197%26dopt%3DAbstract Authors: Pendin D, McNew JA, Daga A The endoplasmic reticulum is a multifunctional organelle composed of functionally and morphologically distinct domains. These include the relatively planar nuclear envelope and the peripheral ER, a network of sheet-like cisternae interconnected with tubules that spread throughout the cytoplasm. The ER is highly dynamic and the shape of its domains as well as their relative content are in constant flux. The multiple forces driving these morphological changes depend on the interaction between the ER and microtubules, membrane fusion and fission events and the action of proteins capable of actively shaping membranes. The interplay between these forces is ultimately responsible for the dynamic morphology of the ER, which in turn is crucial for properly e... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4912700 Wed, 01 Jun 2011 23:00:00 +0100 4912700 http://www.medworm.com/index.php?rid=4912711&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21632231%26dopt%3DAbstract Authors: Hagedorn EJ, Sherwood DR Cell invasion through basement membrane (BM) is a specialized cellular behavior critical to many normal developmental events, immune surveillance, and cancer metastasis. A highly dynamic process, cell invasion involves a complex interplay between cell-intrinsic elements that promote the invasive phenotype, and cell-cell and cell-BM interactions that regulate the timing and targeting of BM transmigration. The intricate nature of these interactions has made it challenging to study cell invasion in vivo and model in vitro. Anchor cell invasion in Caenorhabditis elegans is emerging as an important experimental paradigm for comprehensive analysis of BM invasion, revealing the gene networks that specify invasive behavior and the interactions that occur at th... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4912711 Sun, 29 May 2011 23:00:00 +0100 4912711 http://www.medworm.com/index.php?rid=4912742&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21616652%26dopt%3DAbstract Authors: Boscher C, Dennis JW, Nabi IR Glycosylation is a common posttranslational modification of proteins and lipids of the secretory pathway that generates binding sites for galactose-specific lectins or galectins. Branching of Asn-linked (N-)glycans by the N-acetylglucosaminyltransferases (Mgat genes) increases affinity for galectins. Both tissue-specific expression of the enzymes and the metabolic supply of sugar-nucleotides to the ER and Golgi regulate glycan distribution while protein sequences specify NXS/T site multiplicity, providing metabolic and genetic contributions to galectin-glycoprotein interactions. Galectins cross-link glycoproteins forming dynamic microdomains or lattices that regulate various mediators of cell adhesion, migration, proliferation, survival and differ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4912742 Mon, 23 May 2011 23:00:00 +0100 4912742 http://www.medworm.com/index.php?rid=4865908&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21592757%26dopt%3DAbstract Authors: Hetzer M, Cavalli G PMID: 21592757 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4865908 Sun, 15 May 2011 23:00:00 +0100 4865908 http://www.medworm.com/index.php?rid=4865907&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21592758%26dopt%3DAbstract Authors: Neisch AL, Fehon RG The cell cortex serves as a critical nexus between the extracellular environment/cell membrane and the underlying cytoskeleton and cytoplasm. In many cells, the cell cortex is organized and maintained by the Ezrin, Radixin and Moesin (ERM) proteins, which have the ability to interact with both the plasma membrane and filamentous actin. Although this membrane-cytoskeletal linkage function is critical to stability of the cell cortex, recent studies indicate that this is only a part of what ERMs do in many cells. In addition to their role in binding filamentous actin, ERMs regulate signaling pathways through their ability to bind transmembrane receptors and link them to downstream signaling components. In this review we discuss recent evidence in a variety of ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4865907 Sun, 15 May 2011 23:00:00 +0100 4865907 http://www.medworm.com/index.php?rid=4865911&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21571517%26dopt%3DAbstract Authors: Okiyoneda T, Apaja PM, Lukacs GL Cellular proteostasis (or protein homeostasis) depends on the timely folding and disposal of conformationally damaged polypeptides during their life span at all subcellular locations. This process is particularly important for membrane proteins confined to the cell surface with crucial regulatory role in cellular homoeostasis and intercellular communication. Accumulating evidences indicate that membrane proteins exported from the endoplasmic reticulum (ER) are subjected to peripheral quality control (QC) along the late secretory and endocytic pathways, as well as at the plasma membrane (PM). Recently identified components of the PM QC recognition and effector mechanisms responsible for ubiquitination and lysosomal degradation of conformationall... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4865911 Thu, 12 May 2011 23:00:00 +0100 4865911 http://www.medworm.com/index.php?rid=4865910&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21571518%26dopt%3DAbstract Authors: Borowiec JA, Schildkraut CL Chromosomal DNA replication in mammals initiates from replication origins whose activity differs in accordance with cell type and differentiation state. In addition to origins that are active in unperturbed conditions, chromosomes also contain dormant origins that can become functional in response to certain genotoxic stress conditions. Improper regulation of origin usage can cause genomic instability leading to tumorigenesis. We review findings from recent single-molecule DNA fiber studies examining replication of the mouse immunoglobulin heavy chain (Igh) locus, in which origin activity over a 400kb region is subject to dramatic developmental regulation. Possible models are discussed to explain such differential origin usage, particularly during r... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4865910 Thu, 12 May 2011 23:00:00 +0100 4865910 http://www.medworm.com/index.php?rid=4865909&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21571519%26dopt%3DAbstract Authors: Giuliani F, Grieve A, Rabouille C Most proteins follow the classical secretory pathway from the endoplasmic reticulum, via the Golgi, to the plasma membrane or extracellular medium. However, some proteins reach these final destinations by two alternative routes. One sustains the extracellular delivery of cytoplasmic proteins that lack a signal peptide, the other supports the transport of transmembrane proteins to the plasma membrane in a manner that bypasses the Golgi. Here, we highlight the observation that some unconventional secretion events are triggered by cellular stress. Furthermore, one Golgi protein, Golgi Re-Assembly and Stacking Protein (GRASP), has been shown to be essential to both types of unconventional secretion and we discuss ways in which it may support these... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4865909 Thu, 12 May 2011 23:00:00 +0100 4865909 http://www.medworm.com/index.php?rid=4865913&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21570275%26dopt%3DAbstract Authors: Babst M Multivesicular bodies (MVBs) are endosomes that have internalized portions of the limiting membrane into the compartment, thereby forming intralumenal vesicles. This vesicle formation is unusual in that it is directed away from the cytoplasm, which requires a unique mechanism unlike any mechanism described for other vesicle formation events. The best contenders for the machinery that drives MVB vesicle formation are the ESCRT protein complexes. However, increasing evidence suggests that lipids may play a key role in this membrane-deformation process. This review attempts to combine the seemingly contradictory findings into a MVB vesicle formation model that is based on a lipid-driven and ESCRT-regulated mechanism. PMID: 21570275 [PubMed - as supplied by publisher] ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4865913 Tue, 10 May 2011 23:00:00 +0100 4865913 http://www.medworm.com/index.php?rid=4865912&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21570276%26dopt%3DAbstract Authors: Calvo F, Sahai E The invasion of cancer is a major clinical problem. It is now apparent that invasion is not a simply a cancer cell autonomous process but relies on a complex network of paracrine interactions. Furthermore, this network can change as cancer cells disseminate. Here we summarise the key components of the network and their mechanisms of communication. Finally, we discuss the difficulties and opportunities that this complex network of interactions presents during cancer therapy. PMID: 21570276 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4865912 Tue, 10 May 2011 23:00:00 +0100 4865912 http://www.medworm.com/index.php?rid=4865915&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21565481%26dopt%3DAbstract Authors: Kageyama Y, Zhang Z, Sesaki H Mitochondrial division has emerged as a key mechanism for this essential organelle to maintain its structural integrity, intracellular distribution, and functional competence. An evolutionarily conserved dynamin-related GTPase, Dnm1p/Drp1, interacts with other proteins to form the core machinery involved in mitochondrial division. We summarize recent progress in understanding how the division machinery assembles onto mitochondria and how mitochondrial division contributes to cellular physiology and human diseases. PMID: 21565481 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4865915 Mon, 09 May 2011 23:00:00 +0100 4865915 http://www.medworm.com/index.php?rid=4865914&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21565482%26dopt%3DAbstract Authors: Robinson SD, Hodivala-Dilke KM Integrins are a family of cell-extracellular matrix adhesion molecules that play important roles in tumor angiogenesis. αvβ3-Integrin has received much attention as a potential anti-angiogenic target because it is upregulated in tumor-associated blood vessels. Agents targeting αvβ3-integrin are now showing some success in phase III clinical trails for the treatment of glioblastoma, but the exact function of this integrin in tumor angiogenesis is still relatively unknown. This review highlights some of the recent data illustrating that β3-integrins play both pro-angiogenic and anti-angiogenic roles in tumor angiogenesis depending on the context. Specifically we will discuss how the following differentially influence β3-integrin's role in tum... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4865914 Mon, 09 May 2011 23:00:00 +0100 4865914 http://www.medworm.com/index.php?rid=4865916&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21561755%26dopt%3DAbstract Authors: Pozzi A, Zent R Organ branching morphogenesis is a complex process that requires many coordinated cell functions, including cell migration, proliferation, and polarization. This process is regulated at numerous levels, including spatial and temporal expression of transcription factors and their regulators; growth factors and their receptors; as well as cell-cell and cell-extracellular matrix interactions. Integrins and dystroglycan are transmembrane receptors that control both the adhesion of cells to matrix components as well as transduction of signaling coming from and directed to the matrix. In this article we review current advances defining the roles of these receptors in branching morphogenesis focusing on the major epithelial cell derived structures in mammals, namely s... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4865916 Sun, 08 May 2011 23:00:00 +0100 4865916 http://www.medworm.com/index.php?rid=4813120&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21555211%26dopt%3DAbstract Authors: Toulmay A, Prinz WA Membrane contact sites (MCSs) are formed by the close apposition of membranes of two organelles. They are zones where signals and small molecules, such as lipids and calcium, are exchanged between intracellular compartments. The past few years have seen considerable progress in our understanding of how MCSs form and facilitate the exchange of lipids and signals. Here we summarize what has been learned about MCSs between the endoplamic reticulum (ER) and the plasma membrane, the ER and mitochondria, and the ER and endosomes or lysosomes. These findings suggest that we are just beginning to understand how MCSs form and function. PMID: 21555211 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4813120 Fri, 06 May 2011 23:00:00 +0100 4813120 http://www.medworm.com/index.php?rid=4813122&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21550788%26dopt%3DAbstract Authors: Destaing O, Block MR, Planus E, Albiges-Rizo C Invadosomes are adhesive mechanosensory modules composed of a dense F-actin core surrounded by a ring of adhesion molecules and able to infiltrate compact tissue environment in physiological and pathological conditions. These structures comprise podosomes that are found in a variety of cells under physiological conditions and invadopodia in transformed or cancer cells. Invadosomes are regulated by extracellular matrix signals and are endowed with degradative machinery for extracellular matrix. The ability of extracellular matrix signals to orchestrate the building, dynamics, and function of invadosomes is based on mechano-chemical integrin outside-in signaling and requires integrin cross-talk. This review highlights recent finding... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4813122 Thu, 05 May 2011 23:00:00 +0100 4813122 http://www.medworm.com/index.php?rid=4813121&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21550789%26dopt%3DAbstract Authors: Anitei M, Hoflack B The trans-Golgi network is a major sorting platform of the secretory pathway from which proteins and lipids, both newly synthesized and retrieved from endocytic compartments, are targeted to different destinations. These sorting processes occur during the formation of pleomorphic tubular-vesicular carriers. The past years have provided insights into basic mechanisms coordinating the spatial and temporal organization of machineries necessary for the segregation of membrane components into distinct microdomains, for the bending, elongation, and fission of corresponding membranes, thus revealing a complex interplay of protein-protein and protein-lipid interactions. PMID: 21550789 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4813121 Thu, 05 May 2011 23:00:00 +0100 4813121 http://www.medworm.com/index.php?rid=4813123&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21546233%26dopt%3DAbstract Authors: Schiefermeier N, Teis D, Huber LA Cell migration is a complex biological process that is under the tight control of diverse signaling events. While many of the involved signaling molecules diffuse rapidly within cells, it now seems that certain key regulators of cell migration prefer to travel on endosomes. In this review we will discuss the multiple roles of signaling endosomes in regulation of local migration stimuli, dynamics of focal adhesions, cell contractility and locomotion. PMID: 21546233 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4813123 Mon, 02 May 2011 23:00:00 +0100 4813123 http://www.medworm.com/index.php?rid=4813124&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21501958%26dopt%3DAbstract Authors: Carracedo A, Ito K, Pandolfi PP The promyelocytic leukemia (PML) protein is the core component of nuclear substructures that host more than 70 proteins, termed nuclear domains 10 or PML-nuclear bodies. PML was first identified as the gene participating in the translocation responsible for the pathogenesis of acute promyelocytic leukemia (APL). The notion that PML is a tumor suppressor gene was soon extrapolated from leukemia to solid tumors. The last decade has radically changed the view of how this tumor suppressor is regulated, how it can be therapeutically targeted, and how it functions. Notably, one of the most recent and striking features uncovered is how PML regulates cellular homeostasis outside its original niche in the nucleus. These new findings open an exciting new ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4813124 Fri, 15 Apr 2011 23:00:00 +0100 4813124 http://www.medworm.com/index.php?rid=4813126&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21489772%26dopt%3DAbstract We describe recent experiments that suggest that long-range interactions between active functional elements are sufficient to drive folding of local chromatin domains into compact globular states. We propose that chromatin globules are commonly formed along chromosomes, in a cell type specific pattern, as a result of frequent long-range interactions among active genes and nearby regulatory elements. Further, we speculate that increasingly longer range interactions can drive aggregation of groups of globular domains. This process would yield a compartmentalized chromosome conformation, consistent with recent observations obtained with genome-wide chromatin interaction mapping. PMID: 21489772 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4813126 Mon, 11 Apr 2011 23:00:00 +0100 4813126 http://www.medworm.com/index.php?rid=4813125&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21489773%26dopt%3DAbstract Authors: Ball AR, Yokomori K Technical advances in recent years, such as laser microirradiation and chromatin immunoprecipitation, have led to further understanding of DNA damage responses and repair processes as they happen in vivo and have allowed us to better evaluate the activities of new factors at damage sites. Facilitated by these tools, recent studies identified the unexpected roles of heterochromatin factors in DNA damage recognition and repair, which also involves poly(ADP-ribose) polymerases (PARPs). The results suggest that chromatin at damage sites may be quite structurally dynamic during the repair process, with transient intervals of 'closed' configurations before a more 'open' arrangement that allows the repair machinery to access damaged DNA. PMID: 21489773 [PubMed... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4813125 Sun, 10 Apr 2011 23:00:00 +0100 4813125 http://www.medworm.com/index.php?rid=4705802&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21478005%26dopt%3DAbstract Authors: Lejeune E, Allshire RC Epigenetic mechanisms regulate genome structure and expression profiles in eukaryotes. RNA interference (RNAi) and other small RNA-based chromatin-modifying activities can act to reset the epigenetic landscape at defined chromatin domains. Centromeric heterochromatin assembly is a RNAi-dependent process in the fission yeast Schizosaccharomyces pombe, and provides a paradigm for detailed examination of such epigenetic processes. Here we review recent progress in understanding the mechanisms that underpin RNAi-mediated heterochromatin formation in S. pombe. We discuss recent analyses of the events that trigger RNAi and manipulations which uncouple RNAi and chromatin modification. Finally we provide an overview of similar molecular machineries across specie... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4705802 Wed, 06 Apr 2011 23:00:00 +0100 4705802 http://www.medworm.com/index.php?rid=4705803&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21474295%26dopt%3DAbstract Authors: Platta HW, Stenmark H Many cellular signaling processes are governed by endocytosis through the internalization of plasma membrane receptors. This receptor clearance defines the quality with which a cell can react to extracellular stimuli. However, growing evidence indicates that endocytosis also enables the formation of endosome-specific signal transduction complexes. Their activity is controlled by the balanced trafficking of receptors and signaling molecules through the endocytic compartments. These are commonly divided into early endosomes, recycling endosomes, and late endosomes. Recent progress has been made in the understanding of the biogenesis of these organelles, highlighting their dynamic interconversion, maturation and also the generation of heterogenous subdomains... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4705803 Mon, 04 Apr 2011 23:00:00 +0100 4705803 http://www.medworm.com/index.php?rid=4705805&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21470839%26dopt%3DAbstract Authors: Heermann DW In vivo, chromosomes due to dynamic association with protein factors fold to form three-dimensional structures. Many experiments have paved the way to understand folding and the nuclear architecture of the genome. On the basis of these experiments and models a fundamental understanding of the key principles that drive the physical organization has become possible through the concepts of loop and entropy. Using the concept of loop, models are now able to reproduce the results from several of the experiments within the framework of loop and entropy. Linking biological function to structure they moreover are able to make predictions. PMID: 21470839 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4705805 Sun, 03 Apr 2011 23:00:00 +0100 4705805 http://www.medworm.com/index.php?rid=4705804&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21470840%26dopt%3DAbstract We describe the distinct location and dynamics of CenH3, H3.3, and H2AZ at the centromere during the cell cycle. This leads us to present the current view concerning modes of incorporation at this chromosomal landmark. Finally, we highlight the importance of histone variants in the crosstalk between centric and pericentric domains for maintaining centromere identity. PMID: 21470840 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4705804 Sun, 03 Apr 2011 23:00:00 +0100 4705804 http://www.medworm.com/index.php?rid=4705806&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21466956%26dopt%3DAbstract This article aims at providing a brief update on the importance of clathrin-independent endocytic mechanisms, how the processes are regulated differentially, for instance on the poles of polarized cells, and the challenges in studying them. PMID: 21466956 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4705806 Sat, 02 Apr 2011 23:00:00 +0100 4705806 http://www.medworm.com/index.php?rid=4705809&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21450447%26dopt%3DAbstract Authors: Geyer PK, Vitalini MW, Wallrath LL Eukaryotic genomes are divided into chromosomes that occupy defined regions or territories within the nucleus. These chromosome territories (CTs) are arranged based on the transcriptional activity and chromatin landscape of domains. In general, transcriptionally silent domains reside at the nuclear periphery, whereas active domains locate within the interior. Changes in nuclear position are observed for stress-induced and developmentally regulated tissue-specific genes. Upon activation, these genes move away from a CT to inter-chromosomal space containing nuclear bodies enriched in gene expression machinery. Gene activation is not always accompanied by movement, as positioning is dictated by many determinants, including gene structure and the... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4705809 Sun, 27 Mar 2011 23:00:00 +0100 4705809 http://www.medworm.com/index.php?rid=4705808&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21450448%26dopt%3DAbstract Authors: Fujita N, Yoshimori T Autophagy is primarily a non-selective intracellular bulk degradation process. However, it was recently shown that ubiquitin-positive substrates, such as protein aggregates, mitochondria, peroxisomes, and invading bacteria, are selectively targeted to lysosomes via autophagy. Thus, ubiquitination seems to function as a general tag for selective autophagy in mammalian cells. This review discusses the present model of how autophagy sequesters invading bacteria through ubiquitination. PMID: 21450448 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4705808 Sun, 27 Mar 2011 23:00:00 +0100 4705808 http://www.medworm.com/index.php?rid=4705807&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21450449%26dopt%3DAbstract Authors: Kelly BT, Owen DJ The accurate distribution and recycling of transmembrane proteins amongst the membrane-bound organelles of the cell is vital to ensure its correct functioning. Transmembrane protein cargo destined for clathrin-mediated endocytosis and transport along the endocytic pathway is sorted into transport vesicles by interactions with adaptors, which simultaneously link clathrin to the membrane. Clathrin adaptors recognize a variety of signals present in the cytoplasmic portions of cargo proteins; recent structural, biophysical and cell biological studies have elucidated new types of cargo-adaptor interactions and probed the molecular mechanisms regulating cargo selection and vesicle maturation. Here, we review this recent progress in the context of our existing knowl... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4705807 Sun, 27 Mar 2011 23:00:00 +0100 4705807 http://www.medworm.com/index.php?rid=4411757&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21242077%26dopt%3DAbstract Authors: Arib G, Akhtar A Nuclear pore complexes play a central role in controlling the traffic between the nucleus and the cytoplasm. Progress during the last decade has highlighted nuclear periphery components as novel players in chromatin organization, gene regulation, and genome stability. For instance, lamins associate with repressive chromatin while nuclear pores tend to associate with active chromatin. Interestingly, nucleoporins (Nups) act not only at the nuclear periphery but also in the nucleoplasm. Here we provide an overview of the latest findings and discuss the functional importance of nucleoporin association with specific genes, their role in transcriptional memory, the coupling of transcription and mRNA export, and genome integrity. PMID: 21242077 [PubMed - as suppl... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4411757 Sat, 15 Jan 2011 00:00:00 +0100 4411757 http://www.medworm.com/index.php?rid=4411756&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21242078%26dopt%3DAbstract This article emphasizes that the time is right to coordinate these approaches for a new initiative on single cell imaging of biological molecules. PMID: 21242078 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4411756 Sat, 15 Jan 2011 00:00:00 +0100 4411756 http://www.medworm.com/index.php?rid=4343826&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21227675%26dopt%3DAbstract Authors: Rodríguez-Navarro S, Hurt E Regulation of gene expression can occur at many different levels. One important step in the gene expression process is the transport of mRNA from the nucleus to the cytoplasm. In recent years, studies have described how nuclear mRNA export depends on the steps preceding and following transport through nuclear pore complexes. These include gene activation, transcription, mRNA processing and mRNP assembly and disassembly. In this review, we summarise recent insights into the links between these steps in the gene expression cascade. PMID: 21227675 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4343826 Mon, 10 Jan 2011 00:00:00 +0100 4343826 http://www.medworm.com/index.php?rid=4343828&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21190822%26dopt%3DAbstract Authors: Gautel M In striated muscle sarcomeres, the contractile actin and myosin filaments are organised by a subset of specialised cytoskeletal proteins, the sarcomeric cytoskeleton. They include α-actinin, myomesin, and the giant proteins titin, obscurin and nebulin, which combine architectural, mechanical and signalling functions. Mechanics and signalling in the sarcomere appear tightly interdependent, but the exact contributions of the various sarcomeric cytoskeleton proteins to strain handling or signalling are only just emerging. General mechanisms of cytoskeletal mechanics and signalling may be gleaned from the sarcomere as a specialised actomyosin system. Recent work has led to insight into the interactions, structure, and mechanical stability of sarcomeric protein complexes ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4343828 Mon, 27 Dec 2010 00:00:00 +0100 4343828 http://www.medworm.com/index.php?rid=4343827&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21190823%26dopt%3DAbstract Authors: Ridley A, Heald R PMID: 21190823 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4343827 Mon, 27 Dec 2010 00:00:00 +0100 4343827 http://www.medworm.com/index.php?rid=4343829&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21177090%26dopt%3DAbstract Authors: Mellad JA, Warren DT, Shanahan CM Like other spectrin repeat proteins, nesprins co-ordinate and maintain cellular architecture by linking membranous organelles to the cytoskeleton. However nuclear envelope (NE) nesprins, uniquely hardwire the nuclear lamina to the cytoskeleton and molecular motors. Emerging evidence suggests that nesprins also form a continuous network linking the plasma membrane to the NE that potentially translates mechanical stimuli into nuclear reorganisation. Surprisingly, this network is also essential for cytoskeletal organisation and its disruption has dramatic effects on nuclear migration, centrosomal positioning, focal adhesion maturation and cell motility. Herein we review recent advances in our understanding of how nesprins couple to various filame... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4343829 Mon, 20 Dec 2010 00:00:00 +0100 4343829 http://www.medworm.com/index.php?rid=4343831&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21169003%26dopt%3DAbstract Authors: Lucas JS, Bossen C, Murre C There is now substantial evidence that the eukaryotic nucleus consists of highly organized structures. Among such structures are transcription factories that consist of an ensemble of genes recruited by the RNA polymerase machinery. Here we suggest that antigen receptor variable regions are similarly organized. Specifically, we propose that the immunoglobulin heavy chain locus variable gene segments are anchored to the base of rosettes, wrapping around a cavity that contains the recombination machinery. We suggest that the folding of the chromatin fiber into rosettes underpins a crucial mechanism by which antigen receptor diversity is generated. PMID: 21169003 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4343831 Fri, 17 Dec 2010 00:00:00 +0100 4343831 http://www.medworm.com/index.php?rid=4343830&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21169004%26dopt%3DAbstract Authors: Cenci S, van Anken E, Sitia R Plasma cells differentiate from B lymphocytes to sustain antibody production. As professional secretors, they allow dissecting proteostasis in the exocytic compartment, the stresses that protein production entails and their possible roles in signaling. Most plasma cells are short-lived to limit antibody responses. After a few days of intense immunoglobulin production, they undergo apoptosis, offering a unique model of cellular senescence. Recent observations reveal that proteotoxic stresses physiologically contribute to regulate their biogenesis, function and lifespan, explaining partly the sensitivity of multiple myeloma cells to proteasome inhibitors. This essay summarizes these plasma cell lessons, and their general implications for the regulat... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4343830 Fri, 17 Dec 2010 00:00:00 +0100 4343830 http://www.medworm.com/index.php?rid=4343832&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21168319%26dopt%3DAbstract Authors: Oslowski CM, Urano F Diabetes mellitus is a group of common metabolic disorders defined by hyperglycemia. One of the most important factors contributing to hyperglycemia is dysfunction and death of β cells. Increasing experimental, clinical, and genetic evidence indicates that endoplasmic reticulum (ER) stress plays an important role in β cell dysfunction and death during the progression of type 1 and type 2 diabetes as well as genetic forms of diabetes such as Wolfram syndrome. The mechanisms of ER stress-mediated β cell dysfunction and death are complex and not homogenous. Here we review the recent key findings on the role of ER stress and the unfolded protein response (UPR) in β cells and the mechanisms of ER stress-mediated β cell dysfunction and death. Complete under... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4343832 Thu, 16 Dec 2010 00:00:00 +0100 4343832 http://www.medworm.com/index.php?rid=4343834&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21146390%26dopt%3DAbstract Authors: Shore GC, Papa FR, Oakes SA Inability to meet protein folding demands within the endoplasmic reticulum (ER) activates the unfolded protein response (UPR), a signaling pathway with both adaptive and apoptotic outputs. While some secretory cell types have a remarkable ability to increase protein folding capacity, their upper limits can be reached when pathological conditions overwhelm the fidelity and/or output of the secretory pathway. Irremediable 'ER stress' induces apoptosis and contributes to cell loss in several common human diseases, including type 2 diabetes and neurodegeneration. Researchers have begun to elucidate the molecular switches that determine when ER stress is too great to repair and the signals that are then sent from the UPR to execute the cell. PMID: 21... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4343834 Thu, 09 Dec 2010 00:00:00 +0100 4343834 http://www.medworm.com/index.php?rid=4343833&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21146391%26dopt%3DAbstract Authors: Ong DS, Kelly JW Inheriting a mutant misfolding-prone protein that cannot be efficiently folded in a given cell type(s) results in a spectrum of human loss-of-function misfolding diseases. The inability of the biological protein maturation pathways to adapt to a specific misfolding-prone protein also contributes to pathology. Chemical and biological therapeutic strategies are presented that restore protein homeostasis, or proteostasis, either by enhancing the biological capacity of the proteostasis network or through small molecule stabilization of a specific misfolding-prone protein. Herein, we review the recent literature on therapeutic strategies to ameliorate protein misfolding diseases that function through either of these mechanisms, or a combination thereof, and provide... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4343833 Thu, 09 Dec 2010 00:00:00 +0100 4343833 http://www.medworm.com/index.php?rid=4343835&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21144725%26dopt%3DAbstract Authors: Feige MJ, Hendershot LM Proteins that are expressed outside the cell must be synthesized, folded, and assembled in a way that ensures they can function in their designate location. Accordingly, these proteins are primarily synthesized in the endoplasmic reticulum (ER), which has developed a chemical environment more similar to that outside the cell. This organelle is equipped with a variety of molecular chaperones and folding enzymes that both assist the folding process, while at the same time exerting tight quality control measures that are largely absent outside the cell. A major post-translational modification of ER-synthesized proteins is disulfide bridge formation, which is catalyzed by the family of protein disulfide isomerases. As this covalent modification provides uni... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4343835 Tue, 07 Dec 2010 00:00:00 +0100 4343835 http://www.medworm.com/index.php?rid=4251951&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21131189%26dopt%3DAbstract Authors: Roth DM, Balch WE Protein function is generated and maintained by the proteostasis network (PN) (Balch et al. (2008) Science, 319:916). The PN is a modular, yet integrated system unique to each cell type that is sensitive to signaling pathways that direct development and aging, and respond to folding stress. Mismanagement of protein folding and function triggered by genetic, epigenetic and environmental causes poses a major challenge to human health and lifespan. Herein, we address the impact of proteostasis defined by the FoldFx model on our understanding of protein folding and function in biology. FoldFx describes how general proteostasis control (GPC) enables the polypeptide chain sequence to achieve functional balance in the context of the cellular proteome. By linking tog... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4251951 Fri, 03 Dec 2010 00:00:00 +0100 4251951 http://www.medworm.com/index.php?rid=4251952&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21130639%26dopt%3DAbstract Authors: Kasza KE, Zallen JA Contractile actin-myosin networks generate forces that drive cell shape changes and tissue remodeling during development. These forces can also actively regulate cell signaling and behavior. Novel features of actin-myosin network dynamics, such as pulsed contractile behaviors and the regulation of myosin localization by tension, have been uncovered in recent studies of Drosophila. In vitro studies of single molecules and reconstituted protein networks reveal intrinsic properties of motor proteins and actin-myosin networks, while in vivo studies have provided insight into the regulation of their dynamics and organization. Analysis of the complex behaviors of actin-myosin networks will be crucial for understanding force generation in actively remodeling cells... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4251952 Thu, 02 Dec 2010 00:00:00 +0100 4251952 http://www.medworm.com/index.php?rid=4221297&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21109415%26dopt%3DAbstract Authors: Friedl P, Wolf K, Lammerding J During cell migration, the movement of the nucleus must be coordinated with the cytoskeletal dynamics at the leading edge and trailing end, and, as a result, undergoes complex changes in position and shape, which in turn affects cell polarity, shape, and migration efficiency. We here describe the steps of nuclear positioning and deformation during cell polarization and migration, focusing on migration through three-dimensional matrices. We discuss molecular components that govern nuclear shape and stiffness, and review how nuclear dynamics are connected to and controlled by the actin, tubulin and intermediate cytoskeleton-based migration machinery and how this regulation is altered in pathological conditions. Understanding the regulation of nucle... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4221297 Tue, 23 Nov 2010 00:00:00 +0100 4221297 http://www.medworm.com/index.php?rid=4202684&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21095111%26dopt%3DAbstract Authors: Bowman GR, Lyuksyutova AI, Shapiro L Many recent studies have revealed exquisite subcellular localization of proteins, DNA, and other molecules within bacterial cells, giving credence to the concept of prokaryotic anatomy. Common sites for localized components are the poles of rod-shaped cells, which are dynamically modified in composition and function in order to control cellular physiology. An impressively diverse array of mechanisms underlies bacterial polarity, including oscillatory systems, phospho-signaling pathways, the sensing of membrane curvature, and the integration of cell cycle regulators with polar maturation. PMID: 21095111 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4202684 Sat, 20 Nov 2010 00:00:00 +0100 4202684 http://www.medworm.com/index.php?rid=4202686&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21094034%26dopt%3DAbstract Authors: Rutkevich LA, Williams DB Protein folding within the endoplasmic reticulum occurs in conjunction with a complex array of molecular chaperones and folding catalysts that assist the folding process as well as function in quality control processes to monitor the outcome. In this review, we summarize recent advances in the calnexin/calreticulin chaperone system that is directed primarily toward Asn-linked glycoproteins, as well as the protein disulfide isomerase family of enzymes that catalyze disulfide formation, reduction, and isomerization. We highlight issues related to function and substrate specificity as well as the functional interplay between the two systems. PMID: 21094034 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4202686 Fri, 19 Nov 2010 00:00:00 +0100 4202686 http://www.medworm.com/index.php?rid=4202685&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21094035%26dopt%3DAbstract Authors: Arias E, Cuervo AM Chaperone-mediated autophagy is a selective mechanism for degradation of soluble cytosolic proteins in lysosomes that distinguishes itself from other autophagic pathways by the selectivity with which CMA substrates are targeted for degradation. The recent molecular dissection of this autophagic pathway and the development of experimental models with compromised CMA have unveiled the important contribution of this pathway to protein quality control. In fact, CMA activation seems to be a common mechanism of cellular defense against proteotoxicity. PMID: 21094035 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4202685 Thu, 18 Nov 2010 00:00:00 +0100 4202685 http://www.medworm.com/index.php?rid=4202690&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21093242%26dopt%3DAbstract Authors: Van Doren M PMID: 21093242 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4202690 Wed, 17 Nov 2010 00:00:00 +0100 4202690 http://www.medworm.com/index.php?rid=4202689&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21093243%26dopt%3DAbstract Authors: Kimata Y, Kohno K Upon endoplasmic reticulum (ER) stress, ER-located transmembrane stress sensors evoke diverse protective responses. Although ER stress-dependent activation of the sensor proteins is partly explained through their negative regulation by the ER-located chaperone BiP under non-stress conditions, each of the sensors is also regulated by distinct mechanism(s). For instance, yeast Ire1 is fully activated via its direct interaction with unfolded proteins accumulated in the ER. This insight is consistent with a classical notion that unfolded proteins per se trigger ER-stress responses, while various stress stimuli also seem to activate individual sensors independently of unfolded proteins and in a stimuli-specific manner. These properties may account for the differen... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4202689 Wed, 17 Nov 2010 00:00:00 +0100 4202689 http://www.medworm.com/index.php?rid=4202688&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21093244%26dopt%3DAbstract Authors: Firat-Karalar EN, Welch MD In cells the de novo nucleation of actin filaments from monomers requires actin-nucleating proteins. These fall into three main families - the Arp2/3 complex and its nucleation promoting factors (NPFs), formins, and tandem-monomer-binding nucleators. In this review, we highlight recent advances in understanding the molecular mechanism of actin nucleation by both well-characterized and newly identified nucleators, and explore current insights into their cellular functions in membrane trafficking, cell migration and division. The mechanisms and functions of actin nucleators are proving to be more complex than previously considered, with extensive cooperation and overlap in their cellular roles. PMID: 21093244 [PubMed - as supplied by publisher] (So... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4202688 Wed, 17 Nov 2010 00:00:00 +0100 4202688 http://www.medworm.com/index.php?rid=4202687&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21093245%26dopt%3DAbstract Authors: Zhao H, Pykäläinen A, Lappalainen P Dynamic plasma membrane rearrangements occur during many cellular processes including endocytosis, morphogenesis, and migration. Actin polymerization together with proteins that directly deform membranes, such as the BAR superfamily proteins, is essential for generation of membrane invaginations during endocytosis. Importantly, recent studies revealed that direct membrane deformation contributes also to the formation of plasma membrane protrusions such as filopodia and lamellipodia. Inverse BAR (I-BAR) domain proteins bind phosphoinositide-rich membrane with high affinity and generate negative membrane curvature to induce plasma membrane protrusions. I-BAR domain proteins, such as IRSp53, MIM, ABBA, and IRTKS also harbor many protein-prote... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4202687 Wed, 17 Nov 2010 00:00:00 +0100 4202687 http://www.medworm.com/index.php?rid=4187137&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21087849%26dopt%3DAbstract Authors: Menzies FM, Moreau K, Rubinsztein DC A large group of diseases, termed protein misfolding disorders, share the common feature of the accumulation of misfolded proteins. The possibility of a common mechanism underlying either the pathogenesis or therapy for these diseases is appealing. Thus, there is great interest in the role of protein degradation via autophagy in such conditions where the protein is found in the cytoplasm. Here we review the growing evidence supporting a role for autophagic dysregulation as a contributing factor to protein accumulation and cellular toxicity in certain protein misfolding disorders and discuss the available evidence that upregulation of autophagy may be a valuable therapeutic strategy. PMID: 21087849 [PubMed - as supplied by publisher] (So... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4187137 Wed, 17 Nov 2010 00:00:00 +0100 4187137 http://www.medworm.com/index.php?rid=4187138&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21075612%26dopt%3DAbstract Authors: Bernasconi R, Molinari M The endoplasmic reticulum (ER) is the site of maturation for secretory and membrane proteins in eukaryotic cells. Unsuccessful folding attempts are eventually interrupted and most folding-defective polypeptides are dislocated across the ER membrane and degraded by cytosolic proteasomes in a complex series of events collectively defined as ER-associated degradation (ERAD). Uncontrolled ERAD activity might prematurely interrupt ongoing folding programs. At steady state, this is prevented by ERAD tuning, that is, the removal of select ERAD regulators from the ER and their degradation by proteasomes and by endo-lysosomal proteases. In Coronaviruses infected cells, the formation of LC3-I coated vesicles containing ERAD regulators cleared from the ER lumen i... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4187138 Fri, 12 Nov 2010 00:00:00 +0100 4187138 http://www.medworm.com/index.php?rid=4187139&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21074980%26dopt%3DAbstract Authors: Jaumouillé V, Grinstein S Particle engulfment during phagocytosis has long been appreciated to be an active, actin-driven process. By contrast, the preceding stage - securing the target to the surface of the phagocyte - was thought to result from the passive diffusion of receptors along the membrane towards their ligands on the particle surface. Recent evidence, however, challenges this notion, demonstrating that receptors do not diffuse freely along the phagocyte surface and that actin polymerization and tyrosine phosphorylation are required for optimal particle binding. The interpretation and significance of these observations are the subject of this opinion piece. PMID: 21074980 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4187139 Thu, 11 Nov 2010 00:00:00 +0100 4187139 http://www.medworm.com/index.php?rid=4169141&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21071196%26dopt%3DAbstract Authors: Lowe M The Golgi apparatus is a universal feature of eukaryotes, carrying out the key functions of processing, sorting and trafficking of newly synthesized membrane and secretory proteins. The Golgi apparatus has a clearly defined structure, comprising stacks of flattened cisternal membranes that in vertebrates are connected to form a ribbon. How this structure is maintained and how it relates to the functions of the Golgi apparatus has long been an area of interest. In this review I describe recent progress in the identification and characterization of the molecular machinery that together help generate the characteristic organization of this organelle. PMID: 21071196 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4169141 Tue, 09 Nov 2010 00:00:00 +0100 4169141 http://www.medworm.com/index.php?rid=4125350&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21030233%26dopt%3DAbstract Authors: Murray SM, Yang SY, Van Doren M Sex determination is regulated very differently in the soma vs. the germline, yet both processes are critical for the creation of the male and female gametes. In general, the soma plays an essential role in regulating sexual identity of the germline. However, in some species, such as Drosophila and mouse, the sex chromosome constitution of the germ cells makes an autonomous contribution to germline sexual development. Here we review how the soma and germline cooperate to determine germline sexual identity for some important model systems, the fly, the worm and the mouse, and discuss some of the implications of 'dual control' (soma plus germline) as compared to species where germline sex is dictated only by the surrounding soma. PMID: 2103023... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4125350 Tue, 26 Oct 2010 00:00:00 +0100 4125350 http://www.medworm.com/index.php?rid=4125349&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21030234%26dopt%3DAbstract Authors: Liang Y, Hetzer MW As the gatekeepers of the eukaryotic cell nucleus, nuclear pore complexes (NPCs) mediate all molecular trafficking between the nucleoplasm and the cytoplasm. In recent years, transport-independent functions of NPC components, nucleoporins, have been identified including roles in chromatin organization and gene regulation. Here, we summarize our current view of the NPC as a dynamic hub for the integration of chromatin regulation and nuclear trafficking and discuss the functional interplay between nucleoporins and the nuclear genome. PMID: 21030234 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4125349 Tue, 26 Oct 2010 00:00:00 +0100 4125349 http://www.medworm.com/index.php?rid=4125348&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21030235%26dopt%3DAbstract Authors: Mariño G, Madeo F, Kroemer G Although autophagy has frequently been viewed as a cell death mechanism in the mammalian system, it is now considered as indispensable for the homeostasis of cells, tissues, and organisms. Basal or stress-induced autophagy plays essential and diverse roles in a variety of tissues, due to its cytoprotective properties. In this review, we briefly discuss the different homeostatic functions of autophagy that have been finely dissected in mammals through the generation and characterization of animal models with tissue-specific autophagic alterations. In addition, and given the importance of constitutive autophagy in neuronal tissues, we describe in more detail the specific roles of autophagy in the central nervous system (CNS). Finally, we discuss the... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4125348 Tue, 26 Oct 2010 00:00:00 +0100 4125348 http://www.medworm.com/index.php?rid=4108248&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20974528%26dopt%3DAbstract Authors: Ohta S, Wood L, Bukowski-Wills JC, Rappsilber J, Earnshaw WC Mitotic chromosomes are the iconic structures into which the genome is packaged to ensure its accurate segregation during mitosis. Although they have appeared on countless journal cover illustrations, there remains no consensus on how the chromatin fiber is packaged during mitosis. In fact, work in recent years has both added to existing controversies and sparked new ones. By contrast, there has been very significant progress in determining the protein composition of isolated mitotic chromosomes. Here, we discuss recent studies of chromosome organization and provide an in depth description of the latest proteomics studies, which have at last provided us with a definitive proteome for vertebrate chromosomes. PMID:... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4108248 Fri, 22 Oct 2010 23:00:00 +0100 4108248 http://www.medworm.com/index.php?rid=4108249&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20970977%26dopt%3DAbstract Authors: Pfaffenbach KT, Lee AS GRP78 is a major endoplasmic reticulum chaperone as well as a master regulator of the unfolded protein response. In addition to playing an essential role in early embryonic development, recent studies have emerged specifically implicating GRP78 and chaperone integrity in the aging process and age-related diseases. Another exciting discovery is the regulation of GRP78 by insulin/IGF-1 signaling pathways impacting cell proliferation and survival. Mouse models of cancer, in combination with cell culture studies, validate the critical role of GRP78 in tumorigenesis and tumor angiogenesis. Further, these studies demonstrate the ability of GRP78 to suppress oncogenic PI3K/AKT signaling. The discovery of cell surface GRP78, in cancer cells and cells undergoing ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4108249 Wed, 20 Oct 2010 23:00:00 +0100 4108249 http://www.medworm.com/index.php?rid=4088890&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20951019%26dopt%3DAbstract Authors: Eun SH, Gan Q, Chen X Germ cells and somatic cells have the identical genome. However, unlike the mortal fate of somatic cells, germ cells have the unique ability to differentiate into gametes that retain totipotency and produce an entire organism upon fertilization [1]. The processes by which germ cells differentiate into gametes, and those by which gametes become embryos, involve dramatic cellular differentiation accompanied by drastic changes in gene expression, which are tightly regulated by genetic circuitries as well as epigenetic mechanisms [2,3]. Epigenetic regulation refers to heritable changes in gene expression that are not due to changes in primary DNA sequence. The past decade has witnessed an ever-increasing understanding of epigenetic regulation in many differen... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4088890 Tue, 12 Oct 2010 23:00:00 +0100 4088890 http://www.medworm.com/index.php?rid=4077925&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20947321%26dopt%3DAbstract Authors: Tarbashevich K, Raz E In many species, primordial germ cells (PGCs) migrate from the position where they are specified to the site where the gonad develops, where they differentiate into sperm and egg. Germ cells thus serve as an excellent model for studying cell migration in the context of the live organism. In recent years, a number of cues directing the migration of the cells towards their target were identified and some of the relevant molecules and biochemical pathways were revealed. In this review we present those results, focusing on 'cell mechanics' of the process including cell adhesion, traction generation and cell polarization. PMID: 20947321 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4077925 Mon, 11 Oct 2010 23:00:00 +0100 4077925 http://www.medworm.com/index.php?rid=4077926&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20943362%26dopt%3DAbstract Authors: Verlhac MH, Terret ME, Pintard L In metazoans the oocyte-to-embryo transition occurs in the absence of mRNA transcription and relies entirely on maternally provided mRNA and proteins. We review here recent findings illustrating the importance of degradation of key proteins allowing essential cell cycle transitions as well as important remodelling of the oocyte to produce a totipotent zygote. By following the chronological order of events, we update recent discoveries on the instrumental role of the cullin-RING and APC/C ubiquitin-ligases in promoting meiosis resumption and the oocyte-to-embryo transition. PMID: 20943362 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4077926 Sun, 10 Oct 2010 23:00:00 +0100 4077926 http://www.medworm.com/index.php?rid=4045653&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20889324%26dopt%3DAbstract Authors: McCall K Necrosis has been thought to be an accidental or uncontrolled type of cell death rather than programmed. Recent studies from diverse organisms show that necrosis follows a stereotypical series of cellular and molecular events: swelling of organelles, increases in reactive oxygen species and cytoplasmic calcium, a decrease in ATP, activation of calpain and cathepsin proteases, and finally rupture of organelles and plasma membrane. Genetic and chemical manipulations demonstrate that necrosis can be inhibited, indicating that necrosis can indeed be controlled and follows a specific 'program.' This review highlights recent findings from C. elegans, yeast, Dictyostelium, Drosophila, and mammals that collectively provide evidence for conserved mechanisms of necrosis. PM... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4045653 Thu, 30 Sep 2010 23:00:00 +0100 4045653 http://www.medworm.com/index.php?rid=4045654&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20888210%26dopt%3DAbstract Authors: Lopez J, Meier P The processes of dying are as tightly regulated as those of growth and proliferation, and together they establish a finely tuned balance that ensures proper organ size and function. Failure in the regulation of these responses lies at the heart of many human diseases. Certain members of the inhibitor of apoptosis (IAP) protein family function as important gatekeepers of cell death and survival. While IAPs can regulate cell death by controlling caspases, they also modulate other signalling processes that impact on cell viability. Probably the most important contribution of IAPs to cell survival and tumorigenesis resides in the ability of a number of IAPs to act as ubiquitin-E3 ligases regulating NF-κB signalling. Here, we discuss the latest insights into the u... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4045654 Tue, 28 Sep 2010 23:00:00 +0100 4045654 http://www.medworm.com/index.php?rid=4010329&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20864325%26dopt%3DAbstract Authors: Uhlmann F, Salvesen G PMID: 20864325 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4010329 Mon, 20 Sep 2010 23:00:00 +0100 4010329 http://www.medworm.com/index.php?rid=4010339&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20850289%26dopt%3DAbstract Authors: Kobayashi T, Sokabe M Cell motility, spreading, proliferation and differentiation are critically influenced by substrate rigidity. To sense substrate rigidity, cells apply traction forces to cell-substrate adhesions via actin stress fibers (SFs) and measure mechanical responses of the substrate. Besides mechanosensitive adaptor proteins, mechanosensitive (MS) channels are involved in the substrate rigidity sensing. MS channels located at or near focal adhesions (FAs) convert the rigidity-dependent stress generated in SF/FA system into the level of cytoplasmic Ca(2+) concentration ([Ca(2+)]cyt) by locally altering their Ca(2+) permeability. Besides by external forces, cells spontaneously generate rigidity-dependent localized [Ca(2+)]cyt increases, implicating MS channels as int... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4010339 Tue, 14 Sep 2010 23:00:00 +0100 4010339 http://www.medworm.com/index.php?rid=4010338&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20850290%26dopt%3DAbstract Authors: Friedl P, Zallen JA PMID: 20850290 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=4010338 Tue, 14 Sep 2010 23:00:00 +0100 4010338 http://www.medworm.com/index.php?rid=3982260&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20846840%26dopt%3DAbstract Authors: Impens F, Vandekerckhove J, Gevaert K The recent introduction of positional proteomics made it possible to screen for protease processing events on a proteome-wide scale. As a highly regulated and protease-dependent process, cell death has been particularly well-studied with these emerging technologies. This review provides an overview of the results obtained at the exciting interface between proteomics, protease biology and cell death. PMID: 20846840 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3982260 Mon, 13 Sep 2010 23:00:00 +0100 3982260 http://www.medworm.com/index.php?rid=3982259&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20846841%26dopt%3DAbstract Authors: Ryoo HD, Baehrecke EH Apoptosis and autophagic cell death occur during Drosophila development, and recent advances in their mechanisms have been made. As in other organisms, apoptosis is executed by caspases. In living cells, caspases are kept in check through a combination of IAP-binding and proteolytic inhibition. Once a cell commits to apoptosis, phagocytes recognize them through the immuno-receptor-like proteins Draper and Simu, and initiate corpse engulfment. Drosophila research has significantly contributed to the idea that autophagy is required for certain forms of cell death, and that caspase function in autophagic cell death depends on cell context. Surprisingly, the cell corpse engulfment receptor Draper also functions in autophagic cell death. These advances facilit... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3982259 Mon, 13 Sep 2010 23:00:00 +0100 3982259 http://www.medworm.com/index.php?rid=3982261&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20833011%26dopt%3DAbstract Authors: Thompson BJ In single-celled life forms, the rate of cell growth and division is principally determined by the availability of nutrients. Multicellular organisms operate very differently, with cell growth and division also under the control of developmental programs that instruct cell behaviour according to a cell's position and orientation relative to others, and according to the mechanical forces that the cell experiences. In the fruit fly Drosophila, these three inputs have been shown to act via signalling pathways, transcription factors and microRNAs to regulate the rate of cell growth and division and can also act upon the mitotic spindle to control the orientation of cell division. PMID: 20833011 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Bi... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3982261 Wed, 08 Sep 2010 23:00:00 +0100 3982261 http://www.medworm.com/index.php?rid=3982262&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20832275%26dopt%3DAbstract Authors: Gray RS, Cheung KJ, Ewald AJ The cellular mechanisms driving mammalian epithelial morphogenesis are of significant fundamental and practical interest. Historically, these processes have been difficult to study directly, owing to the opacity and relative inaccessibility of mammalian tissues. Recent experimental advances in timelapse imaging and in 3D organotypic culture have enabled direct observation of epithelial morphogenesis. In the mammary gland, branching morphogenesis is observed to proceed through a novel form of collective epithelial migration. The active unit of morphogenesis is a multilayered epithelium with reduced apico-basal polarity, within which cells rearranged vigorously. From within this multilayered state, new ducts initiate and elongate into the matrix with... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3982262 Tue, 07 Sep 2010 23:00:00 +0100 3982262 http://www.medworm.com/index.php?rid=3962550&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20829015%26dopt%3DAbstract Authors: Yanowitz J The perpetuation of most eukaryotic species requires differentiation of pluripotent progenitors into egg and sperm and subsequent fusion of these gametes to form a new zygote. Meiosis is a distinguishing feature of gamete formation as it leads to the twofold reduction in chromosome number thereby maintaining ploidy across generations. This process increases offspring diversity through the random segregation of chromosomes and the exchange of genetic material between homologous parental chromosomes, known as meiotic crossover recombination. These exchanges require the establishment of unique and dynamic chromatin configurations that facilitate cohesion, homolog pairing, synapsis, double strand break formation and repair. The precise orchestration of these events is c... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3962550 Tue, 07 Sep 2010 23:00:00 +0100 3962550 http://www.medworm.com/index.php?rid=3962549&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20829016%26dopt%3DAbstract Authors: Sanz-Moreno V, Marshall CJ Due to the use of intra-vital imaging techniques and assays for cell migration into 3D matrices there has recently been much interest in different modes of tumour cell migration. Individually moving tumour cells can move either in an elongated-protrusive manner or in rounded, so-called 'amoeboid' modes. This review summarises ongoing efforts to delineate the cell signalling pathways that underlie these different forms of movement. PMID: 20829016 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3962549 Mon, 06 Sep 2010 23:00:00 +0100 3962549 http://www.medworm.com/index.php?rid=3956076&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20822888%26dopt%3DAbstract Authors: Albini A, Noonan DM Invasive and metastatic cells must cross basement membranes (BMs) in order to disseminate to distant sites. The 'chemoinvasion assay' using a reconstituted basement membrane, matrigel, in Boyden blind-well chambers was developed 25 years ago as a tool for invasion and metastasis research. Since then, it was adapted for investigation of how different cells types engage with and penetrate basement membrane, including research in angiogenesis, invasive cell migration, protease functions, and preclinical development of anti-invasive and anti-angiogenic agents. As novel mechanisms of metastasis and angiogenesis come to light and old paradigms are challenged, we examine how the assay can still provide innovative insights. We review established applications and va... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3956076 Thu, 02 Sep 2010 23:00:00 +0100 3956076 http://www.medworm.com/index.php?rid=3956075&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20822889%26dopt%3DAbstract Authors: van der Heijden GW, Castañeda J, Bortvin A Epigenetic reprogramming of embryonic mouse germ cells involves DNA demethylation of the genome that is accompanied by derepression of transposable elements (TEs). Threatening the genome's integrity, TE activation is efficiently countered by the concerted action of de novo DNA methylation and PIWI-interacting small RNAs (piRNAs). Recent studies have closely examined the subcellular localization of various piRNA pathway proteins in fetal prospermatogonia of wild-type and piRNA pathway mutant mice. Our survey highlights hierarchies and partnerships between the members of this ancient defensive mechanism. Overall, the elaborate cytoplasmic compartmentalization of the piRNA pathway in fetal prospermatogonia provides a highly informativ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3956075 Thu, 02 Sep 2010 23:00:00 +0100 3956075 http://www.medworm.com/index.php?rid=3956074&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20822890%26dopt%3DAbstract Authors: Zhang H, Gally C, Labouesse M Genetic analysis in model organisms has recently achieved a detailed molecular description of many key cellular processes controlling embryonic morphogenesis. To understand higher order tissue morphogenesis, we now need to define how these processes become integrated across different cell groups and cell layers. Here, we review progress in this fast moving area, which was to a large degree made possible by novel imaging methods and the increasingly frequent use of modeling. Discussing examples from Caenorhabditis elegans and Drosophila embryos, two powerful and simple models, we highlight novel principles relying in part on mechanical tension, and outline the role of junctions as signal integrators. PMID: 20822890 [PubMed - as supplied by publ... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3956074 Thu, 02 Sep 2010 23:00:00 +0100 3956074 http://www.medworm.com/index.php?rid=3956070&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20822891%26dopt%3DAbstract Authors: Egeblad M, Rasch MG, Weaver VM The extracellular matrix (ECM) is a key regulator of cell and tissue function. Traditionally, the ECM has been thought of primarily as a physical scaffold that binds cells and tissues together. However, the ECM also elicits biochemical and biophysical signaling. Controlled proteolysis and remodeling of the ECM network regulate tissue tension, generate pathways for migration, and release ECM protein fragments to direct normal developmental processes such as branching morphogenesis. Collagens are major components of the ECM of which basement membrane type IV and interstitial matrix type I are the most prevalent. Here we discuss how abnormal expression, proteolysis and structure of these collagens influence cellular functions to elicit multiple effe... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3956070 Thu, 02 Sep 2010 23:00:00 +0100 3956070 http://www.medworm.com/index.php?rid=3956069&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20822892%26dopt%3DAbstract Authors: Medalia O, Geiger B Focal adhesions (FAs) are highly dynamic multi-protein complexes, through which cells interact with the extracellular matrix (ECM) via integrin receptors. These large assemblies, which typically measure several micrometers in diameter, mediate interactions of cells with external surfaces, and are linked at their cytoplasmic faces with F-actin bundles. Over the last four decades, the molecular diversity of these adhesions and their roles in cell migration and matrix sensing have been extensively studied. Microscopy-based research is considered critical for characterizing and understanding the nature of these assemblies. Here, we review the contributions of, advanced microscopy to the characterization of the functional architecture of integrin-mediated, cell-... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3956069 Thu, 02 Sep 2010 23:00:00 +0100 3956069 http://www.medworm.com/index.php?rid=3956085&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20817425%26dopt%3DAbstract Authors: Nakamura A, Shirae-Kurabayashi M, Hanyu-Nakamura K Germ cells, the progenitors of gametes, are often specified and segregated from somatic lineages early in embryogenesis. As germ cells are essential to create the next generation in sexually reproducing organisms, they must be prevented from differentiating inappropriately into somatic cells. In Drosophila and Caenorhabditis elegans embryos, this is governed by the transient and global repression of mRNA transcription. Furthermore, the inhibition of somatic transcriptional programs is also crucial for germ cell specification in the mouse. Therefore, the active repression of somatic transcriptional programs appears to be a common mechanism for launching the germline. In this review, we will discuss the mechanisms of transcripti... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3956085 Wed, 01 Sep 2010 23:00:00 +0100 3956085 http://www.medworm.com/index.php?rid=3956084&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20817426%26dopt%3DAbstract Authors: Schejter ED, Baylies MK From the muscles that control the blink of your eye to those that allow you to walk, the basic architecture of muscle is the same: muscles consist of bundles of the unit muscle cell, the muscle fiber. The unique morphology of the individual muscle fiber is dictated by the functional demands necessary to generate and withstand the forces of contraction, which in turn leads to movement. Contractile muscle fibers are elongated, syncytial cells, which interact with both the nervous and skeletal systems to govern body motion. In this review, we focus on three key cell-cell and cell-matrix contact processes, that are necessary to create this exquisitely specialized cell: cell fusion, cell elongation, and establishment of a myotendinous junction. We address th... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3956084 Wed, 01 Sep 2010 23:00:00 +0100 3956084 http://www.medworm.com/index.php?rid=3956083&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20817427%26dopt%3DAbstract Authors: Mace PD, Riedl SJ Multi-cellular animals have evolved a variety of mechanisms to respond to diverse apoptotic stimuli. In general these proceed through activation of apical caspases and culminate in executioner caspase activation and cell death. Because of the breadth of possible initiators, various molecular platforms are used to trigger different apical caspases. Although some common protein domains are used to assemble the apoptosome, the PIDDosome and death receptor complexes, an array of checks-and-balances are employed to ensure appropriate activation. Notwithstanding, these pathways share the underlying principle of proximity-dependent activation and post-translational modification. Here we will describe our current structural understanding of assembly and regulation of... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3956083 Wed, 01 Sep 2010 23:00:00 +0100 3956083 http://www.medworm.com/index.php?rid=3956080&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20817428%26dopt%3DAbstract Authors: Eilken HM, Adams RH The vertebrate body contains an extensive blood vessel network that forms, with a few exceptions, by endothelial sprouting from the existing vasculature. This process, termed angiogenesis, involves complex and highly dynamic interactions between endothelial cells and their environment. Pro-angiogenic signals, such as VEGF, promote endothelial motility, filopodia extension and proliferation, and, together with Notch signaling, controls whether specific endothelial cells become lead tip cells or trailing stalk cells. Sprouts then convert into endothelial tubules and form connections with other vessels, which requires the local suppression of motility and the formation of new cell-cell junctions. We here review the dynamics of angiogenesis in the context of ke... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3956080 Wed, 01 Sep 2010 23:00:00 +0100 3956080 http://www.medworm.com/index.php?rid=3956079&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20817499%26dopt%3DAbstract Authors: Jiang K, Akhmanova A Microtubule ends serve as sites of tubulin addition and removal, and at the same time play crucial roles in microtubule capture, stabilization and attachment to different cellular structures. Microtubule plus and minus-ends possess distinct structural and dynamic properties, and are recognized, bound and regulated by diverse factors. These include specific capping factors such as gamma-tubulin, motors, such as plus-end and minus-end directed kinesins, highly specialized kinetochore-bound microtubule-associated proteins, and comet-making plus-end tracking proteins such as EB1 and its partners. Here, we provide an overview of microtubule tip-interacting proteins and the mechanisms responsible for their association with microtubule ends, and discuss the funct... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3956079 Tue, 31 Aug 2010 23:00:00 +0100 3956079 http://www.medworm.com/index.php?rid=3956078&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20817500%26dopt%3DAbstract Authors: Yuan H, Yamashita YM Germline stem cells (GSCs) sustain gametogenesis during the life of organisms. Recent progress has substantially extended our understanding of GSC behavior, including the mechanisms of stem cell self-renewal, asymmetric stem cell division, stem cell niches, dedifferentiation, and tissue aging. GSCs typically are highly proliferative, owing to organismal requirement to produce large number of differentiated cells. While many somatic stem cells are multipotent, with multiple differentiation pathways, GSCs are unipotent. For these relatively simple characteristics (e.g. constant proliferation and unipotency), GSCs have served as ideal model systems for the study of adult stem cell behavior, leading to many important discoveries. Here, we summarize recent prog... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3956078 Tue, 31 Aug 2010 23:00:00 +0100 3956078 http://www.medworm.com/index.php?rid=3956077&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20817501%26dopt%3DAbstract Authors: Wallingford JB Planar cell polarity signaling governs a wide array of polarized cell behaviors in animals. Recent reports now show that PCP signaling is essential for the directional beating of motile cilia. Interestingly, PCP signaling acts in a variety of ciliated cell types that use motile cilia to generate directional fluid flow in very different ways. This review will synthesize these recent papers and place them in context with previous studies of PCP signaling in polarized cellular morphogenesis and collective cell movement. PMID: 20817501 [PubMed - as supplied by publisher] (Source: Current Opinion in Cell Biology) Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3956077 Tue, 31 Aug 2010 23:00:00 +0100 3956077 http://www.medworm.com/index.php?rid=3934830&cid=s_35490_171_f&fid=35490&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20813513%26dopt%3DAbstract Authors: Yang A, Wilson NS, Ashkenazi A Proapoptotic receptor agonists (PARAs) targeting death receptors (DRs) 4 and 5 hold promise for cancer therapy based on their selective ability to kill malignant versus healthy cells. Emerging clinical results have confirmed that DR4/5 PARAs are relatively well-tolerated and suitable for further investigation. Given that some cancer cell lines and models are not sensitive to PARAs, it is important to develop strategies to identify what specific types of tumor cells may be most responsive to PARA-based therapy and how to overcome apoptosis resistance mechanisms in tumors. Here we review the molecular and biological determinants of responsiveness to PARAs in cancer cells, and discuss the potential for predictive biomarkers and drug combination stra... Current Opinion in Cell Biology journals http://www.medworm.com/rss/comments.php?id=3934830 Mon, 30 Aug 2010 23:00:00 +0100 3934830