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Differences in c-jun and nNOS expression levels in motoneurons following different kinds of axonal injury in adult rats.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the peripheral nervous system (PNS), root avulsion causes motoneuron degeneration, but the majority of motoneurons can survive axotomy. In order to study the mechanism of motoneuron degeneration, we compared the expression patterns of c-jun and neuronal nitric oxide synthase (nNOS), the well-known molecular players in PNS regeneration and degeneration, among adult rats having undergone axotomy (Ax), avulsion (Av), or pre-axotomy plus secondary avulsion (Ax + Av) of the brachial plexus. Our results showed that the highest and longest-lasting c-jun activation occurred in Ax, which was much stronger than those in Av an...
Source: Brain Cell Biology - February 24, 2009 Category: Cytology Authors: Zhou LH, Han S, Xie YY, Wang LL, Yao ZB Tags: Brain Cell Biol Source Type: journals

Imaging activity of neuronal populations with new long-wavelength voltage-sensitive dyes.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We have assessed the utility of five new long-wavelength fluorescent voltage-sensitive dyes (VSD) for imaging the activity of populations of neurons in mouse brain slices. Although all the five were capable of detecting activity resulting from activation of the Schaffer collateral-CA1 pyramidal cell synapse, they differed significantly in their properties, most notably in the signal-to-noise ratio of the changes in dye fluorescence associated with neuronal activity. Two of these dyes, Di-2-ANBDQPQ and Di-1-APEFEQPQ, should prove particularly useful for imaging activity in brain tissue and for combining VSD imaging with...
Source: Brain Cell Biology - February 14, 2009 Category: Cytology Authors: Kee MZ, Wuskell JP, Loew LM, Augustine GJ, Sekino Y Tags: Brain Cell Biol Source Type: journals

Editorial: Hello, Goodbye.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19184439 [PubMed - as supplied by publisher]
Source: Brain Cell Biology - January 28, 2009 Category: Cytology Authors: Augustine GJ Tags: Brain Cell Biol Source Type: journals

Direct interaction of SNARE complex binding protein synaphin/complexin with calcium sensor synaptotagmin 1.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Although the binding of synaphin (also called complexin) to the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex is critical for synaptic vesicle exocytosis, the exact role of synaphin remains unclear. Here, we show that synaphin directly binds to synaptotagmin 1, a major Ca(2+) sensor for fast neurotransmitter release, in a 1:1 stoichiometry. Mapping of the synaphin site involved in synaptotagmin 1 binding revealed that the C-terminal region is essential for the interaction between these two proteins. Binding was sensitive to ionic strength, suggesting the involvement of charged re...
Source: Brain Cell Biology - January 9, 2009 Category: Cytology Authors: Tokumaru H, Shimizu-Okabe C, Abe T Tags: Brain Cell Biol Source Type: journals

O-GlcNAc modification of radial glial vimentin filaments in the developing chick brain.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We examined the post-translational modification of intracellular proteins by beta-O-linked N-acetylglucosamine (O-GlcNAc) with regard to neurofilament phosphorylation in the developing chick optic tectum. A regulated developmental pattern of O-GlcNAcylation was discovered in the developing brain. Most notably, discernible staining occurs along radial glial filaments but not along neuronal filaments in vivo. Immunohistochemical analyses in sections of progressive stages of development suggest upregulation of O-GlcNAc in the ependyma, tectofugal neuron bodies, and radial glial processes, but not in axons. In contrast, double...
Source: Brain Cell Biology - January 9, 2009 Category: Cytology Authors: Farach AM, Galileo DS Tags: Brain Cell Biol Source Type: journals

Increased expression of beta-catenin in brain microvessels of a segmentally trisomic (Ts65Dn) mouse model of Down syndrome.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We examined the distribution of beta-catenin and endogenous blood serum albumin at the ultrastructural level in blood microvessels (capillaries) from brains of control and trisomic Ts65Dn mice. Morphological examination revealed an increased immunolabeling for beta-catenin in endothelial substructures of the capillary network, such as intercellular junctions, cytoplasm, and nuclei. These immunosignals were significantly increased in all endothelial substructures from trisomic mice. These changes, however, did not affect the blood-brain barrier function of the entire microvascular network, because the increased uptake of al...
Source: Brain Cell Biology - January 9, 2009 Category: Cytology Authors: Vorbrodt AW, Li S, Brown WT, Ramakrishna N Tags: Brain Cell Biol Source Type: journals

Reporting neural activity with genetically encoded calcium indicators.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Genetically encoded calcium indicators (GECIs), based on recombinant fluorescent proteins, have been engineered to observe calcium transients in living cells and organisms. Through observation of calcium, these indicators also report neural activity. We review progress in GECI construction and application, particularly toward in vivo monitoring of sparse action potentials (APs). We summarize the extrinsic and intrinsic factors that influence GECI performance. A simple model of GECI response to AP firing demonstrates the relative significance of these factors. We recommend a standardized protocol for evaluating GECIs in...
Source: Brain Cell Biology - October 22, 2008 Category: Cytology Authors: Hires SA, Tian L, Looger LL Tags: Brain Cell Biol Source Type: journals

A heterogeneous "resting" pool of synaptic vesicles that is dynamically interchanged across boutons in mammalian CNS synapses.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Using pHluorin-tagged synaptic vesicle proteins we have examined the partitioning of these probes into recycling and nonrecycling pools at hippocampal nerve terminals in cell culture. Our studies show that for three of the major synaptic vesicle components, vGlut-1, VAMP-2, and Synaptotagmin I, ~50-60% of the tagged protein appears in a recycling pool that responds readily to sustained action potential stimulation by mobilizing and fusing with the plasma membrane, while the remainder is targeted to a nonrecycling, acidic compartment. The fraction of recycling and nonrecycling (or resting) pools varied significantly acr...
Source: Brain Cell Biology - October 22, 2008 Category: Cytology Authors: Fernandez-Alfonso T, Ryan TA Tags: Brain Cell Biol Source Type: journals

Development of microscopic systems for high-speed dual-excitation ratiometric Ca(2+) imaging.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
For quantitative measurements of Ca(2+) concentration ([Ca(2+)]), ratiometric dyes are preferable, because the use of such dyes allows for correction of uneven loading or partitioning of dye within the cell as well as variations in cell thickness. Although dual-excitation ratiometric dyes for measuring [Ca(2+)], such as Fura-2, Fura-Red, and ratiometric-pericam, are widely used for a variety of applications, it has been difficult to use them for monitoring very fast Ca(2+) dynamics or Ca(2+) changes in highly motile cells. To overcome this problem, we have developed three new dual-excitation ratiometry systems. (1) A s...
Source: Brain Cell Biology - October 22, 2008 Category: Cytology Authors: Fukano T, Shimozono S, Miyawaki A Tags: Brain Cell Biol Source Type: journals

Real-time monitoring of cyclic nucleotide signaling in neurons using genetically encoded FRET probes.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Signaling cascades involving cyclic nucleotides play key roles in signal transduction in virtually all cell types. Elucidation of the spatiotemporal regulation of cyclic nucleotide signaling requires methods for tracking the dynamics of cyclic nucleotides and the activities of their regulators and effectors in the native biological context. Here we review a series of genetically encoded FRET-based probes for real-time monitoring of cyclic nucleotide signaling with a particular focus on their implementation in neurons. Current data indicate that neurons have a very active metabolism in cyclic nucleotide signaling, which...
Source: Brain Cell Biology - October 22, 2008 Category: Cytology Authors: Vincent P, Gervasi N, Zhang J Tags: Brain Cell Biol Source Type: journals

Optogenetic probes.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 18941897 [PubMed - as supplied by publisher]
Source: Brain Cell Biology - October 22, 2008 Category: Cytology Authors: Yasuda R, Augustine GJ Tags: Brain Cell Biol Source Type: journals

Improved expression of halorhodopsin for light-induced silencing of neuronal activity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The ability to control and manipulate neuronal activity within an intact mammalian brain is of key importance for mapping functional connectivity and for dissecting the neural circuitry underlying behaviors. We have previously generated transgenic mice that express channelrhodopsin-2 for light-induced activation of neurons and mapping of neural circuits. Here we describe transgenic mice that express halorhodopsin (NpHR), a light-driven chloride pump that can be used to silence neuronal activity via light. Using the Thy-1 promoter to target NpHR expression to neurons, we found that neurons in these mice expressed high l...
Source: Brain Cell Biology - October 17, 2008 Category: Cytology Authors: Zhao S, Cunha C, Zhang F, Liu Q, Gloss B, Deisseroth K, Augustine GJ, Feng G Tags: Brain Cell Biol Source Type: journals

Imaging synaptic inhibition throughout the brain via genetically targeted Clomeleon.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Here we survey a molecular genetic approach for imaging synaptic inhibition. This approach is based on measuring intracellular chloride concentration ([Cl(-)](i)) with the fluorescent chloride indicator protein, Clomeleon. We first describe several different ways to express Clomeleon in selected populations of neurons in the mouse brain. These methods include targeted viral gene transfer, conditional expression controlled by Cre recombination, and transgenesis based on the neuron-specific promoter, thy1. Next, we evaluate the feasibility of using different lines of thy1::Clomeleon transgenic mice to image synaptic inhi...
Source: Brain Cell Biology - October 11, 2008 Category: Cytology Authors: Berglund K, Schleich W, Wang H, Feng G, Hall WC, Kuner T, Augustine GJ Tags: Brain Cell Biol Source Type: journals

Genetically encoded fluorescent sensors of membrane potential.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Imaging activity of neurons in intact brain tissue was conceived several decades ago and, after many years of development, voltage-sensitive dyes now offer the highest spatial and temporal resolution for imaging neuronal functions in the living brain. Further progress in this field is expected from the emergent development of genetically encoded fluorescent sensors of membrane potential. These fluorescent protein (FP) voltage sensors overcome the drawbacks of organic voltage sensitive dyes such as non-specificity of cell staining and the low accessibility of the dye to some cell types. In a transgenic animal, a genetic...
Source: Brain Cell Biology - August 5, 2008 Category: Cytology Authors: Baker BJ, Mutoh H, Dimitrov D, Akemann W, Perron A, Iwamoto Y, Jin L, Cohen LB, Isacoff EY, Pieribone VA, Hughes T, Knöpfel T Tags: Brain Cell Biol Source Type: journals

eNpHR: a Natronomonas halorhodopsin enhanced for optogenetic applications.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Temporally precise inhibition of distinct cell types in the intact nervous system has been enabled by the microbial halorhodopsin NpHR, a fast light-activated electrogenic Cl(-) pump. While neurons can be optically hyperpolarized and inhibited from firing action potentials at moderate NpHR expression levels, we have encountered challenges with pushing expression to extremely high levels, including apparent intracellular accumulations. We therefore sought to molecularly engineer NpHR to achieve strong expression without these cellular side effects. We found that high expression correlated with endoplasmic reticulum (ER)...
Source: Brain Cell Biology - August 2, 2008 Category: Cytology Authors: Gradinaru V, Thompson KR, Deisseroth K Tags: Brain Cell Biol Source Type: journals

Optimizing the spatial resolution of Channelrhodopsin-2 activation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Over the past few years, the light-gated cation channel Channelrhodopsin-2 (ChR2) has seen a remarkable diversity of applications in neuroscience. However, commonly used wide-field illumination provides poor spatial selectivity for cell stimulation. We explored the potential of focal laser illumination to map photocurrents of individual neurons in sparsely transfected hippocampal slice cultures. Interestingly, the best spatial resolution of photocurrent induction was obtained at the lowest laser power. By adjusting the light intensity to a neuron's spike threshold, we were able to trigger action potentials with a spati...
Source: Brain Cell Biology - July 25, 2008 Category: Cytology Authors: Schoenenberger P, Grunditz A, Rose T, Oertner TG Tags: Brain Cell Biol Source Type: journals

FRET imaging and in silico simulation: analysis of the signaling network of nerve growth factor-induced neuritogenesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Genetically encoded probes based on Förster resonance energy transfer (FRET) enable us to decipher spatiotemporal information encoded in complex tissues such as the brain. Firstly, this review focuses on FRET probes wherein both the donor and acceptor are fluorescence proteins and are incorporated into a single molecule, i.e. unimolecular probes. Advantages of these probes lie in their easy loading into cells, the simple acquisition of FRET images, and the clear evaluation of data. Next, we introduce our recent study which encompasses FRET imaging and in silico simulation. In nerve growth factor-induced neurite ou...
Source: Brain Cell Biology - July 25, 2008 Category: Cytology Authors: Nakamura T, Aoki K, Matsuda M Tags: Brain Cell Biol Source Type: journals

Highly sensitive and quantitative FRET-FLIM imaging in single dendritic spines using improved non-radiative YFP.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Two-photon fluorescence lifetime imaging microscopy (TPFLIM) enables the quantitative measurements of fluorescence resonance energy transfer (FRET) in small subcellular compartments in light scattering tissue. We evaluated and optimized the FRET pair of mEGFP (monomeric EGFP with the A206K mutation) and REACh (non-radiative YFP variants) for TPFLIM. We characterized several mutants of REACh in terms of their "darkness," and their ability to act as a FRET acceptor for mEGFP in HeLa cells and hippocampal neurons. Since the commonly used monomeric mutation A206K increases the brightness of REACh, we introduced a different...
Source: Brain Cell Biology - May 30, 2008 Category: Cytology Authors: Murakoshi H, Lee SJ, Yasuda R Tags: Brain Cell Biol Source Type: journals

Brain cell meetings.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Authors: PMID: 18443911 [PubMed - in process]
Source: Brain Cell Biology - December 1, 2006 Category: Cytology Tags: Brain Cell Biol Source Type: journals

Brain cell technology: a valuable new resource for novel techniques.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 18443910 [PubMed - in process]
Source: Brain Cell Biology - December 1, 2006 Category: Cytology Authors: Augustine GJ Tags: Brain Cell Biol Source Type: journals

Imaging synaptic inhibition in transgenic mice expressing the chloride indicator, Clomeleon.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We describe here a molecular genetic approach for imaging synaptic inhibition. The thy-1 promoter was used to express high levels of Clomeleon, a ratiometric fluorescent indicator for chloride ions, in discrete populations of neurons in the brains of transgenic mice. Clomeleon was functional after chronic expression and provided non-invasive readouts of intracellular chloride concentration ([Cl(-)](i)) in brain slices, allowing us to quantify age-dependent declines in resting [Cl(-)](i) during neuronal development. Activation of hippocampal interneurons caused [Cl(-)](i) to rise transiently in individual postsynaptic pyram...
Source: Brain Cell Biology - December 1, 2006 Category: Cytology Authors: Berglund K, Schleich W, Krieger P, Loo LS, Wang D, Cant NB, Feng G, Augustine GJ, Kuner T Tags: Brain Cell Biol Source Type: journals

Distribution of the scaffolding proteins PSD-95, PSD-93, and SAP97 in isolated PSDs.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We compared the distribution of three scaffolding proteins, all belonging to a family of membrane-associated guanylate kinases, thought to have key roles in the organization of the postsynaptic density (PSD). Isolated PSDs readily adhered to treated glass coverslips where they were labeled with immunogold and rotary shadowed for analysis by EM. The distribution of proteins within individual PSDs were measured by counting and mapping individual immunogold particles. PSD-95, as previously described, is distributed evenly throughout the PSD. We find here that PSD-93 has a nearly identical distribution suggesting that PSD-...
Source: Brain Cell Biology - December 1, 2006 Category: Cytology Authors: DeGiorgis JA, Galbraith JA, Dosemeci A, Chen X, Reese TS Tags: Brain Cell Biol Source Type: journals

Differential activation of extracellular signal-regulated kinase 1 and a related complex in neuronal nuclei.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The extracellular signal-regulated kinases 1 and 2 (ERKs 1/2) are known to participate in regulating transcription in response to moderate depolarization, such as synaptic stimulation, but how the same active enzyme can differentially regulate distinct transcriptional programs induced with abnormal depolarization (high potassium) is unknown. We hypothesized that ERK1 or 2 accomplishes this differential nuclear response through close association with other proteins in stable complexes. In support of this hypothesis, we have found that immunoreactivity for an apparent high molecular weight complex containing phospho-ERK1...
Source: Brain Cell Biology - December 1, 2006 Category: Cytology Authors: Lundquist JJ, Dudek SM Tags: Brain Cell Biol Source Type: journals

GABAC receptor subunit mRNA expression in the rat superior colliculus is regulated by calcium channels, neurotrophins, and GABAC receptor activity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The distribution of mRNA for the rho2 subunit of the GABA(C) receptor is much broader in organotypic SC cultures than in vivo, suggesting that GABA(C) receptor expression is regulated by environmental factors. Electrophysiological recordings indicate that neurons in SC cultures have functional GABA(C) receptors, although these receptors exhibited smaller conductance than in vivo, probably due to increased rho2 subunit expression. Adding cortical input, treatment with various neuromodulators, and blocking neuronal activity with TTX failed to affect the expression of rho2 subunits. Electrophysiological recordings reveale...
Source: Brain Cell Biology - December 1, 2006 Category: Cytology Authors: Jost B, Grabert J, Patz S, Schmidt M, Wahle P Tags: Brain Cell Biol Source Type: journals

A practical device for pinpoint delivery of molecules into multiple neurons in culture.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We have developed a device for pinpoint delivery of chemicals, proteins, and nucleic acids into cultured cells. The principle underlying the technique is the flow of molecules from the culture medium into cells through a rupture in the plasma membrane made by a needle puncture. DNA transfection is achieved by stabbing the needle tip into the nucleus. The CellBee device can be attached to any inverted microscope, and molecular delivery can be coupled with conventional live cell imaging. Because the position of the needle relative to the targeted cultured cells is computer-controlled, efficient delivery of molecules such...
Source: Brain Cell Biology - December 1, 2006 Category: Cytology Authors: Hara C, Tateyama K, Akamatsu N, Imabayashi H, Karaki K, Nomura N, Okano H, Miyawaki A Tags: Brain Cell Biol Source Type: journals

Cross talk between vestibular neurons and Schwann cells mediates BDNF release and neuronal regeneration.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
It is now well-established that an active cross-talk occurs between neurons and glial cells, in the adult as well as in the developing and regenerating nervous systems. These functional interactions not only actively modulate synaptic transmission, but also support neuronal growth and differentiation. We have investigated the possible existence of a reciprocal interaction between inner ear vestibular neurons and Schwann cells maintained in primary cultures. We show that ATP released by the extending vestibular axons elevates intracellular calcium levels within Schwann cells. Purinergic activation of the Schwann P2X(7) ...
Source: Brain Cell Biology - June 1, 2006 Category: Cytology Authors: Verderio C, Bianco F, Blanchard MP, Bergami M, Canossa M, Scarfone E, Matteoli M Tags: Brain Cell Biol Source Type: journals

Beta-amyloid enhances intracellular calcium rises mediated by repeated activation of intracellular calcium stores and nicotinic receptors in acutely dissociated rat basal forebrain neurons.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Beta-amyloid, a 39-43 amino acid peptide, may exert its biological effects via neuronal nicotinic acetylcholine receptors. Using the ratiometric dye, fura-2, we examined the effect of soluble beta-amyloid(1-42) on the concentration of intracellular Ca(2+) ([Ca(2+)](i)) in acutely dissociated rat basal forebrain neurons. Focal applications of nicotine (0.5-20 mM), evoked dose-dependent increases in intracellular [Ca(2+)](i) that were mediated by the entry of extracellular Ca(2+) via nicotinic acetylcholine receptors, and the release of intracellular Ca(2+) from stores. With repeated nicotine challenges, the nicotinic re...
Source: Brain Cell Biology - June 1, 2006 Category: Cytology Authors: Chin JH, Tse FW, Harris K, Jhamandas JH Tags: Brain Cell Biol Source Type: journals

CD44 adhesion molecule and neuro-glial proteoglycan NG2 as invasive markers of glioma.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, the expression of ECM-associated and cell-associated proteins such as the transmembrane CD44 adhesion molecule and neuro-glial proteoglycan 2 (NG2), a member of the chondroitin sulfate proteoglycan family, were evaluated during glioma progression, in vitro and in vivo, using a model of a highly invasive and aggressive intracerebral mouse G-26 glioma. We found a marked increase in CD44 and NG2 expression in brain tissue containing glioma. The glioma levels of these proteins gradually increased over time to reach 3-15 times the levels in the contralateral control. NG2 and CD44 expression paralleled progression...
Source: Brain Cell Biology - June 1, 2006 Category: Cytology Authors: Wiranowska M, Ladd S, Smith SR, Gottschall PE Tags: Brain Cell Biol Source Type: journals

Synaptic destabilization by neuronal Nogo-A.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Formation and maintenance of a neuronal network is based on a balance between plasticity and stability of synaptic connections. Several molecules have been found to regulate the maintenance of excitatory synapses but nothing is known about the molecular mechanisms involved in synaptic stabilization versus disassembly at inhibitory synapses. Here, we demonstrate that Nogo-A, which is well known to be present in myelin and inhibit growth in the adult CNS, is present in inhibitory presynaptic terminals in cerebellar Purkinje cells at the time of Purkinje cell-Deep Cerebellar Nuclei (DCN) inhibitory synapse formation and i...
Source: Brain Cell Biology - June 1, 2006 Category: Cytology Authors: Aloy EM, Weinmann O, Pot C, Kasper H, Dodd DA, Rülicke T, Rossi F, Schwab ME Tags: Brain Cell Biol Source Type: journals

Synapsin II negatively regulates catecholamine release.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We have assessed the role of synapsins in catecholamine release by comparing the properties of exocytosis in adrenal chromaffin cells from wild-type and synapsin triple knock-out (TKO) mice. Brief depolarizations led to a greater amount of catecholamine release in chromaffin cells from TKO mice in comparison to chromaffin cells from wild-type mice. This increase in catecholamine release was due to an increased number of exocytotic events, while the properties of individual quanta of released catecholamine were unchanged. Barium ions produced similar amounts of catecholamine release from TKO and wild-type chromaffin cel...
Source: Brain Cell Biology - June 1, 2006 Category: Cytology Authors: Villanueva M, Thornley K, Augustine GJ, Wightman RM Tags: Brain Cell Biol Source Type: journals

Changes in the distribution of calcium calmodulin-dependent protein kinase II at the presynaptic bouton after depolarization.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Phosphorylation of synapsin I by CaMKII has been reported to mobilize synaptic vesicles from the reserve pool. In the present study, the distributions of alpha-CaMKII and of synapsin I were compared in synaptic boutons of unstimulated and stimulated hippocampal neurons in culture by immunogold electron microscopy. CaMKII and synapsin I are located in separate domains in presynaptic terminals of unstimulated neurons. Label for alpha -CaMKII typically surrounds synaptic vesicle clusters and is absent from the inside of the cluster in control synapses. In contrast, intense labeling for synapsin I is found within the vesic...
Source: Brain Cell Biology - June 1, 2006 Category: Cytology Authors: Tao-Cheng JH, Dosemeci A, Winters CA, Reese TS Tags: Brain Cell Biol Source Type: journals

Vesicle pools and synapsins: new insights into old enigmas.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Synapsins are a multigene family of neuron-specific phosphoproteins and comprise the most abundant synaptic vesicle proteins. They have been proposed to tether synaptic vesicles to each other to maintain a reserve pool in the vicinity of the active zone. Such a role is supported by the observation that disruption of synapsin function leads to a depletion of the reserve pool of vesicles and an increase in synaptic depression. However, other functions for synapsins have been proposed as well, and there currently exists no coherent picture of how these abundant proteins modulate synaptic transmission. Here, we discuss nov...
Source: Brain Cell Biology - June 1, 2006 Category: Cytology Authors: Fdez E, Hilfiker S Tags: Brain Cell Biol Source Type: journals

Requirement of TrkB for synapse elimination in developing cerebellar Purkinje cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The receptor tyrosine kinase TrkB and its ligands, brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5 (NT-4/5), are critically important for growth, survival and activity-dependent synaptic strengthening in the central nervous system. These TrkB-mediated actions occur in a highly cell-type specific manner. Here we report that cerebellar Purkinje cells, which are richly endowed with TrkB receptors, develop a normal morphology in trkB-deficient mice. Thus, in contrast to other types of neurons, Purkinje cells do not need TrkB for dendritic growth and spine formation. Instead, we find a moderate delay in the ma...
Source: Brain Cell Biology - February 1, 2006 Category: Cytology Authors: Bosman LW, Hartmann J, Barski JJ, Lepier A, Noll-Hussong M, Reichardt LF, Konnerth A Tags: Brain Cell Biol Source Type: journals

Calcium-dependent trapping of mitochondria near plasma membrane in stimulated astrocytes.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Growing evidence suggests that astrocytes are the active partners of neurons in many brain functions. Astrocytic mitochondria are highly motile organelles which regulate the temporal and spatial patterns of Ca( 2+ ) dynamics, in addition to being a major source of ATP and reactive oxygen species. Previous studies have shown that mitochondria translocate to endoplasmic reticulum during Ca( 2+ ) release from internal stores, but whether a similar spatial interaction between mitochondria and plasma membrane occurs is not known. Using total internal reflection fluorescence (TIRF) microscopy we show that a fraction of mitoc...
Source: Brain Cell Biology - February 1, 2006 Category: Cytology Authors: Kolikova J, Afzalov R, Giniatullina A, Surin A, Giniatullin R, Khiroug L Tags: Brain Cell Biol Source Type: journals

Calcium-induced exocytosis from actomyosin-driven, motile varicosities formed by dynamic clusters of organelles.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Varicosities are ubiquitous neuronal structures that appear as local swellings along neurites of invertebrate and vertebrate neurons. Surprisingly little is known about their cell biology. We use here cultured Aplysia neurons and demonstrate that varicosities are motile compartments that contain large clusters of organelles. The content of varicosities propagate along neurites within the plasma membrane "sleeve", split and merge, or wobble in place. Confocal imaging, retrospective immunolabeling, electron microscopy and pharmacological perturbations reveal that the motility of the varicosities' organelle content occurs...
Source: Brain Cell Biology - February 1, 2006 Category: Cytology Authors: Malkinson G, Fridman ZM, Kamber D, Dormann A, Shapira E, Spira ME Tags: Brain Cell Biol Source Type: journals

A microtubule-based, dynein-dependent force induces local cell protrusions: Implications for neurite initiation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A key event in neurite initiation is the accumulation of microtubule bundles at the neuron periphery. We hypothesized that such bundled microtubules may generate a force at the plasma membrane that facilitates neurite initiation. To test this idea we observed the behavior of microtubule bundles that were induced by the microtubule-associated protein MAP2c. Endogenous MAP2c contributes to neurite initiation in primary neurons, and exogeneous MAP2c is sufficient to induce neurites in Neuro-2a cells. We performed nocodazol washout experiments in primary neurons, Neuro-2a cells and COS-7 cells to investigate the underlying...
Source: Brain Cell Biology - February 1, 2006 Category: Cytology Authors: Dehmelt L, Nalbant P, Steffen W, Halpain S Tags: Brain Cell Biol Source Type: journals

Cell type-specific dendritic polarity in the absence of spatially organized external cues.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Pyramidal neurons of the hippocampus and cortex have polarized dendritic arbors, but little is known about the cellular mechanisms distinguishing apical and basal dendrites. We used morphometric analysis and time lapse imaging of cultured hippocampal neurons to show that glutamatergic neurons develop progressive dendritic asymmetry in the absence of polarized extrinsic cues. Thus, pyramidal neurons have a cellular program for polarized dendrite growth independent of tissue microenvironment. PMID: 17940911 [PubMed - indexed for MEDLINE]
Source: Brain Cell Biology - February 1, 2006 Category: Cytology Authors: Horton AC, Yi JJ, Ehlers MD Tags: Brain Cell Biol Source Type: journals

Electrical coupling between pyramidal cells in adult cortical regions.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Recently, intense interest has focussed on electrical coupling between interneurones in cortical regions and their contributions towards oscillatory network activity. Despite mounting circumstantial evidence that pyramidal cells are also coupled, the paucity of direct evidence has made this controversial. Dual intracellular recordings from pairs of cortical and hippocampal pyramids demonstrated strong, but sparse coupling. Approximately 70% of CA1 pyramids close to the stratum radiatum border were coupled to another pyramid, but only to one or two of their very closest neighbours. On average 25% of the steady state and...
Source: Brain Cell Biology - February 1, 2006 Category: Cytology Authors: Mercer A, Bannister AP, Thomson AM Tags: Brain Cell Biol Source Type: journals

Pyramid power: principal cells of the hippocampus unite!Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Electrical transmission in the mammalian brain is now well established. A new study by Thomson and colleagues elegantly demonstrates coupling between CA1 hippocampal pyramidal cells, which is far more common than previously supposed. Although the history of coupling is extensive, doubt, predjudice, and technical issues long kept it from wide acceptance. Here "spikelets" or "fast prepotentials" are found when two cells are coupled and in this situation result from electrical transmission of impulses from one coupled cell to the other. Interesting questions remain as to whether connexin or pannexin gap junctions serve as...
Source: Brain Cell Biology - February 1, 2006 Category: Cytology Authors: Bennett MV, Pereda A Tags: Brain Cell Biol Source Type: journals