FOXO target gene CTDSP2 regulates cell cycle progression through Ras and p21Cip1/Waf1
Activity of Forkhead box O (FOXO) transcription factors is inhibited by growth factor-PI3K-protein kinase B (PKB)/AKT signalling to control a variety of cellular processes including cell cycle progression. Through comparative analysis of a number of microarray datasets we identified a set of genes commonly regulated by FOXO proteins and PI3K-PKB/AKT, which includes carboxyl-terminal domain small phosphatase 2 (CTDSP2). We validated CTDSP2 as a genuine FOXO target gene and show that ectopic CTDSP2 can induce cell cycle arrest. We analysed transcriptional regulation after CTDSP2 expression and identified extensive regulation...
Source: BJ Signal - May 20, 2015 Category: Biochemistry Authors: D E.A. Kloet, P E Polderman, A Eijkelenboom, L M Smits, M H Van Triest, M C.W Van Den Berg, M J. Groot Koerkamp, D Van Leenen, P Lijnzaad, F C. Holstege, B M.T. Burgering Tags: BJ Signal Source Type: research
The focal adhesion kinase Pyk2 links Ca2{+} signaling to Src family kinase activation and protein tyrosine phosphorylation in thrombin-stimulated platelets
In blood platelets, stimulation of G protein-coupled receptors by thrombin triggers the activation of Src family kinases (SFKs), resulting in the tyrosine-phosphorylation of multiple substrates, but the mechanism underlying this process is still poorly understood. Here we show that the time-dependent protein-tyrosine phosphorylation triggered by thrombin in human or murine platelets was totally suppressed only upon concomitant chelation of intracellular Ca2+ and inhibition of SFKs. Thrombin-induced activation of SFKs was regulated by intracellular Ca2+, and accordingly, the Ca2+ ionophore A23187 was su...
Source: BJ Signal - May 13, 2015 Category: Biochemistry Authors: I Canobbio, L Cipolla, G Francesco Guidetti, D Manganaro, C Visconte, S Kim, M Okigaki, M Falasca, S P Kunapuli, M Torti Tags: BJ Signal Source Type: research
The Two Component Signaling Networks of Mycobacterium tuberculosis Displays Extensive Crosstalk In Vitro
Two component systems (TCSs), which contain paired sensor kinase and response regulator proteins, form the primary apparatus for sensing and responding to environmental cues in bacteria. TCSs are thought to be highly specific, displaying minimal cross-talk, primarily due to the co-evolution of the participating proteins. To assess the level of cross-talk between the TCSs of M. tuberculosis (Mtb), we mapped the complete interactome of the Mtb TCSs using phosphotransfer profiling. Surprisingly, we found extensive crosstalk among the Mtb TCSs, significantly more than that in the TCSs in E. coli or Caulobacter crescentus, ther...
Source: BJ Signal - May 1, 2015 Category: Biochemistry Authors: R Agrawal, A Pandey, M P Rajankar, N M Dixit, D K Saini Tags: BJ Signal Source Type: research
Suppression of Interferon {beta} gene transcription by inhibitors of Bromodomain and Extra-Terminal (BET) family members
Polo-Like Kinase (PLK) inhibitors, such as BI-2536, have been reported to suppress interferon β (IFNβ) gene transcription induced by ligands that activate TLR3 and TLR4. Here, we report that BI-2536 is likely to exert this effect by preventing the interaction of the transcription factors IRF3 and c-Jun with the IFNβ promoter, but without affecting the TANK-binding kinase 1 (TBK1)-catalysed phosphorylation of IRF3 at Ser396, the dimerization and nuclear translocation of IRF3 or the phosphorylation of c-Jun and ATF2. Although BI-2536 inhibits few other kinases tested, it interacts with Bromodomain and Ex...
Source: BJ Signal - April 20, 2015 Category: Biochemistry Authors: N Malik, S Vollmer, S Kumar Nanda, M Lopez-Pelaez, A Prescott, N Gray, P Cohen Tags: BJ Signal Source Type: research
Development of a new model system to dissect isoform specific Akt signaling in adipocytes
Akt kinases are critical signal transducers mediating insulin action. Genetic studies revealed that Akt1 and Akt2 signaling differentially contribute to sustain lipid and glucose homeostasis; howeverAkt isoform-specific effectors remain elusive due to the lack of a suitable model system to mechanistically interrogate Akt isoform-specific signaling. To overcome those technical limitations we developed a novel model system that provides acute and specific control of signaling by Akt isoforms. We generated mutants of Akt1 and Akt2 resistant to the allosteric Akt inhibitor MK-2206. We then developed adipocyte cell lines, in wh...
Source: BJ Signal - April 9, 2015 Category: Biochemistry Authors: E Kajno, T E. McGraw, E Gonzalez Tags: BJ Signal Source Type: research
Intrinsically disordered cytoplasmic domains of two cytokine receptors mediate conserved interactions with membranes
This study presents the first comprehensive structural characterization of any cytokine receptor ICD and demonstrates that the human prolactin and growth hormone receptor ICDs are intrinsically disordered throughout their entire lengths. We show that they interact specifically with hallmark lipids of the inner plasma membrane leaflet through conserved motifs resembling immuno T-cell receptor activation motifs(ITAMs). However, contrary to the observations made for ITAMs, lipid association of the prolactin and growth hormone receptor ICDs was shown to be unaccompanied by changes in transient secondary structure and independe...
Source: BJ Signal - April 7, 2015 Category: Biochemistry Authors: G W. Haxholm, L F. Nikolajsen, J G. Olsen, J Fredsted, F H. Larsen, V Goffin, S F Pedersen, A J Brooks, M J Waters, B B. Kragelund Tags: BJ Biomolecules Source Type: research
Activation of Glycoprotein VI (GPVI) and C-type Lectin-like receptor-2 (CLEC-2) underlies platelet activation by diesel exhaust particles and other charged/hydrophobic ligands
Platelets are activated by a range of stimuli that share little or no resemblance in structure to each other or to recognised ligands, including diesel exhaust particles (DEP), small peptides (4N1-1, Champs, LSARLAF), proteins (histones), and large polysaccharides (fucoidan, dextran sulphate). This miscellaneous group stimulate aggregation of human and mouse platelets through the GPVI-FcR-γ-chain complex and/or CLEC-2 as shown using platelets from mice deficient in either or both of these receptors. In addition, all of these ligands stimulate tyrosine phosphorylation in GPVI/CLEC-2 double-deficient platelets, indica...
Source: BJ Signal - April 7, 2015 Category: Biochemistry Authors: O M Alshehri, S Montague, S Watson, P Carter, N Sarker, B K Manne, J L. C. Miller, A B Herr, A Y Pollitt, C A O'Callaghan, S P Kunapuli, M Arman, C E Hughes, S P Watson Tags: BJ Signal Source Type: research
Processing of Protein ADP-ribosylation by Nudix Hydrolases
ADP-ribosylation is a post-translational modification of proteins found in organisms from all kingdoms of life which regulates many important biological functions including DNA repair, chromatin structure, unfolded protein response, and apoptosis. Several cellular enzymes, such as macrodomain containing proteins PARG and TARG1, reverse protein ADP-ribosylation. Here we show that human Nudix-Type Motif 16 (hNUDT16) represents a new enzyme class that can process protein ADP-ribosylation in vitro, converting it into ribose-5’-phosphate tags covalently attached to the modified proteins. Furthermore, our data show that h...
Source: BJ Signal - March 19, 2015 Category: Biochemistry Authors: L Palazzo, B Thomas, A Jemth, T Colby, O Leidecker, K Feijs, R Zaja, O Loseva, J Carreras Puigvert, I Matic, T Helleday, I Ahel Tags: BJ Signal Source Type: research
Crystal structure of an SH2-kinase construct of c-Abl and effect of the SH2 domain on kinase activity
We present a crystal structure of an SH2-kinase domain construct bound to dasatinib, which contains the relevant interface between the SH2 domain and the N-lobe of the kinase domain. We show that the presence of the SH2 domain enhances kinase activity moderately and that this effect depends on contacts in the SH2-N-lobe interface and is abrogated by specific mutations. Consistently, formation of the interface decreases slightly the association rate of imatinib with the kinase domain. That the effects are small compared to the dramatic in vivo consequences suggests an important function of the SH2-N-lobe interaction might b...
Source: BJ Signal - March 17, 2015 Category: Biochemistry Authors: S G Lorenz, P Deng, O Hantschel, G Superti-Furga, J Kuriyan Tags: BJ Signal Source Type: research
Determinants of oligosaccharide specificity of the carbohydrate binding modules of AMP-activated protein kinase
AMPK-activated protein kinase (AMPK) is a αβγ heterotrimer that is important in regulating energy metabolism in all eukaryotes. The β-subunit exists in two isoforms (β1 and β2) and contains a carbohydrate binding module (CBM) that interacts with glycogen. The two CBM isoforms (β1- and β2-CBM) are near identical in sequence and structure, yet show differences in carbohydrate binding affinity. β2-CBM binds linear carbohydrates with four-fold greater affinity than β1-CBM and binds single α1,6-branched carbohydrates up to 30-fold tighter. To understan...
Source: BJ Signal - March 16, 2015 Category: Biochemistry Authors: J I Mobbs, A Koay, A Di Paolo, M Bieri, E J Petrie, M A Gorman, L Doughty, M W Parker, D Stapleton, M D W Griffin, P R Gooley Tags: BJ Biomolecules Source Type: research
Protein kinase Snf1 is involved in the proper regulation of the unfolded protein response in Saccharomyces cerevisiae.
Glc7 is the only catalytic subunit of the protein phosphatase type 1 in the yeast S. cerevisiae and, together with its regulatory subunits, is involved in many and essential processes. Analysis of the non-essential mutants in the regulatory subunits of Glc7 revealed that the lack of Reg1, and no other subunit, causes hypersensitivity to unfolded-protein-response (UPR)-inducers, which was concomitant with an augmented UPR element-dependent transcriptional response. Glc7-Reg1complex takes part in the regulation of the yeast AMP-activated serine/threonine protein kinase Snf1 in response to glucose. We demonstrate here that th...
Source: BJ Signal - March 2, 2015 Category: Biochemistry Authors: J Ferrer-dalmau, F Randez-Gil, M Marquina, J A Prieto, A Casamayor Tags: BJ Signal Source Type: research
Assembly and structure of Lys33-linked polyubiquitin reveals distinct conformations
Ubiquitylation regulates a multitude of biological processes and this versatility stems from the ability of ubiquitin to form topologically different polymers of eight different linkage types. While some linkages have been studied in detail, other linkage types including Lys33-linked polyubiquitin are poorly understood. Here we identify an enzymatic system for the large-scale assembly of Lys33 chains by combining the HECT (homologous to the E6-AP carboxyl terminus) E3 ligase AREL1 (apoptosis-resistant E3 ubiquitin protein ligase 1) with linkage selective deubiquitinases (DUBs). Moreover, this first characterisation of the ...
Source: BJ Signal - February 27, 2015 Category: Biochemistry Authors: Y Adi Kristariyanto, S Choi, S Abdul Rehman, M Ritorto, D G Campbell, N A Morrice, R Toth, Y Kulathu Tags: BJ Signal Source Type: research
Notch ligand Delta-like1: X-ray crystal structure and binding affinity
The Notch pathway is a fundamental signalling system in most multicellular animals. We have determined the X-ray crystal structure of the extracellular domain of the Notch ligand Delta-like ligand-1 (Dll-1). This is the first structure of a Delta-like ligand. The structure incorporates the N-terminal C2 domain, receptor-binding DSL domain, and the first six (of eight) EGF-like repeats, which form a highly extended conformation, confirmed by analytical ultracentrifugation. Comparison of our structure with a fragment of Jagged1 ligand allows us to dissect the similarities and differences between the ligand families. Differen...
Source: BJ Signal - February 26, 2015 Category: Biochemistry Authors: N J Kershaw, N L Church, M D W Griffin, C S Luo, T E. Adams, A W Burgess Tags: BJ Biomolecules Source Type: research
PAQR3 modulates H3K4 trimethylation by spatial modulation of the regulatory subunits of COMPASS-like complexes in mammalian cells
We report here a new mode of spatial regulation of H3K4 methyltransferase complexes. PAQR3, a tumor suppressor specifically localized in the Golgi apparatus, negatively regulates H3K4 trimethylation (H3K4me3) in mammalian cells. Consistently, HOXC8 and HOXA9 gene expression was negatively regulated by PAQR3 expression levels. Hypoxia-induced H3K4me3 was augmented by PAQR3 knockdown and suppressed by PAQR3 overexpression in AGS gastric cancer cells. PAQR3 was able to interact directly or indirectly with the four members of the WRAD sub-complex and tether them to the Golgi apparatus, accompanied by reduction of histone methy...
Source: BJ Signal - February 23, 2015 Category: Biochemistry Authors: C Liu, Y Zhang, Y Hou, L Shen, Y Li, W Guo, D Xu, G Liu, Z Zhao, K Man, Y Pan, Z Wang, Y Chen Tags: BJ Signal Source Type: research
Small Molecule Inhibitors of ERK-mediated Immediate Early Gene Expression and Proliferation of Melanoma Cells Expressing Mutated BRaf
Constitutive activation of the extracellular signal-regulated kinases 1 and 2 (ERK1/2) are central to regulating the proliferation and survival of many cancer cells. The current inhibitors of ERK1/2 target ATP binding or the catalytic site and are therefore limited in their utility for elucidating the complex biological roles of ERK1/2 through its phosphorylation and regulation of over one hundred substrate proteins. To overcome this limitation, a combination of computational and experimental methods was used to identify small molecular weight inhibitors that are intended to target ERK1/2-substrate docking domains and sele...
Source: BJ Signal - February 19, 2015 Category: Biochemistry Authors: R Samadani, J Zhang, A Brophy, T Oashi, U Deva Priyakumar, E Prabhu Raman, F J. St. John, K Jung, S Fletcher, E Pozharski, A D MacKerell, P S Shapiro Tags: BJ ChemBio Source Type: research
