CD25 and CD69 induction by {alpha}4{beta}1 outside-in signaling requires TCR early signaling complex proteins
Distinct signaling pathways producing diverse cellular outcomes can utilize similar subsets of proteins. For example, proteins from the T cell receptor (TCR) early signaling complex (ESC) are also involved in interferon-α receptor signaling. Defining the mechanism for how these proteins function within a given pathway is important in understanding the integration and communication of signaling networks with one another. We investigated the contributions of the TCR ESC proteins Lck, ZAP-70, Vav1, SLP-76, and LAT to integrin outside-in signaling in human T cells. Lck, ZAP-70, SLP-76, Vav1, and LAT were activated by &#...
Source: BJ Signal - June 11, 2013 Category: Biochemistry Authors: A Cimo, Z Ahmed, B W McIntyre, D E Lewis, J E Ladbury Tags: BJ Signal Source Type: research
Stabilization of the Angiotensin-(1-7) Receptor Mas through Interaction with PSD95
The functions and signaling mechanisms of the angiotensin-(1-7) (Ang-(1-7)) receptor Mas have been studied extensively. However, less attention has been paid to the intracellular regulation of Mas protein. In the present study, PSD95, a novel binding protein of Mas receptor was identified, and their association was further characterized. Mas specifically interacts with the PDZ1-2 but not the PDZ3 domain of PSD95 via Mas carboxyl terminus (Mas-CT), and the last four amino acids (ETVV) of Mas-CT were determined to be essential for this interaction, as shown by the results of GST pull-down, Co-IP and confocal colocalization e...
Source: BJ Signal - May 24, 2013 Category: Biochemistry Authors: W Bian, L Sun, L Yang, J Li, J Hu, S Zheng, R Guo, D Feng, Q Ma, X Shi, Y Xiong, X Yang, R Song, J Xu, S Wang, J He Tags: BJ Signal Source Type: research
PPIP5K1 Modulates Ligand Competition Between Diphosphoinositol Polyphosphates and PtdIns(3,4,5)P3 for Polyphosphoinositide-Binding Domains.
We describe new signalling consequences for PPIP5K1-mediated phosphorylation of InsP6 and 5-InsP7 to 1-InsP7 and InsP8. In NIH-3T3 cells, either hyperosmotic stress or receptor-activation by PDGF promoted translocation of PPIP5K1 from the cytoplasm to the plasma membrane. The PtdIns(3,4,5)P3-binding domain (PBD) in PPIP5K1 recapitulated that translocation. Mutagenesis of PBD to reduce affinity for PtdIns(3,4,5)P3 prevented translocation. Using surface plasmon resonance, we found that PBD association with vesicular PtdIns(3,4,5)P3 was inhibited by InsP6 and diphosphoinositol polyphosphates. However, the inhibition by PPIP5K...
Source: BJ Signal - May 20, 2013 Category: Biochemistry Authors: N A Gokhale, A Zaremba, A K Janoshazi, J D Weaver, S B Shears Tags: BJ Signal Source Type: research
STIM1 negatively regulates Ca2{+} release from the sarcoplasmic reticulum in skeletal myotubes
Stromal interaction molecule 1 (STIM1) mediates store-operated Ca2+ entry (SOCE) in skeletal muscle. However, the direct role(s) of STIM1 in skeletal muscle, such as Ca2+ release from the sarcoplasmic reticulum (SR) for muscle contraction, have not been identified. The times required for the maximal expression of endogenous STIM1 or Orai1, or for the appearance of puncta during the differentiation of mouse primary skeletal myoblasts to myotubes, were all different, and the formation of puncta was detected with no stimulus during differentiation, suggesting that, in skeletal muscle, the formation of puncta is ...
Source: BJ Signal - May 14, 2013 Category: Biochemistry Authors: K Lee, J Woo, J Hwang, C Hyun, C Cho, D Kim, E Lee Tags: BJ Signal Source Type: research
{beta}TrCP interacts with the ubiquitin-dependent endocytosis motif of the GH receptor in an unconventional manner
In this study we show that βTrCP interacts directly via its WD40 domain with the ubiquitin dependent endocytosis motif (UbE) in GHR, promoting GHR ubiquitination in vitro. NMR experiments demonstrated that the UbE motif is essentially unstructured, and together with functional mapping of the UbE and βTrCP WD40 residues necessary for binding, lead to a unique interaction model of βTrCP with GHR-UbE. This interaction is different from the conventional bTrCP-substrate interactions described to date. Therefore, this interaction represents a promising specific target to develop drugs that inhibit GHR endocy...
Source: BJ Signal - April 22, 2013 Category: Biochemistry Authors: A C. da Silva Almeida, H G. Hocking, R Boelens, G J. Strous, A G.S.H. van Rossum Tags: BJ Signal Source Type: research
Elevated SGK1 predicts resistance of breast cancer cells to Akt inhibitors
The majority of human cancers harbour mutations promoting activation of the Akt
protein kinase and Akt inhibitors are being evaluated in clinical trials. An important
question concerns understanding the innate mechanisms that confer resistance of
tumour cells to Akt inhibitors. The Serum and Glucocorticoid regulated Kinase
(SGK) is closely related to Akt and controlled by identical upstream regulators (PI 3-
kinase, PDK1 and mTORC2). Mutations that trigger activation of Akt would also
stimulate SGK. Moreover, Akt and SGK possess analogous substrate specificities and
are likely to phosphorylate overlapping substrates...
Source: BJ Signal - April 15, 2013 Category: Biochemistry Authors: E M Sommer, H Dry, D Cross, S Guichard, B R Davies, D R Alessi Tags: BJ ChemBio Source Type: research
New insight into the catalytic mechanism of histidine phosphatases revealed by a functionally essential arginine within the active sites of the Sts phosphatases.
Sts-1 and Sts-2 are histidine phosphatases that negatively regulate TCR signaling pathways, including those involved in cytokine production. Histidine phosphatases (HPs) play key roles in such varied biological processes as metabolism, development, and intracellular signaling. They differ considerably in primary sequence and substrate specificity, but possess a catalytic core formed by an invariant quartet of active site residues. Two histidines and two arginines cluster together within the HP active site and are thought to participate in a two-step dephosphorylation reaction. To date there has been little insight into add...
Source: BJ Signal - April 9, 2013 Category: Biochemistry Authors: B San Luis, N Nassar, N Carpino Tags: BJ Signal Source Type: research
PFKFB3 activation in cancer cells by the p38/MK2 pathway in response to stress stimuli
We report that exposure of HeLa and T98G cells to different stress stimuli (NaCl, H2O2, UV radiation and anisomycin) leads to a rapid increase (15-30 minutes) in PFKFB3 mRNA levels. The use of specific inhibitors in combination with MK2-deficient cells implicate control by MK2 protein kinase. Transient transfection of HeLa cells with deleted gene promoter constructs allowed us to identify a Serum Response Element (SRE) to which Serum Response Factor (SRF) binds and thus transactivates PFKFB3 gene transcription. Direct Binding of phospho-SRF to the SRE sequence (-918 nt) was confirmed by ChIP (chromatin immunoprecipiation) ...
Source: BJ Signal - April 2, 2013 Category: Biochemistry Authors: L Novellasdemunt, L Bultot, A Manzano, F Ventura, J Rosa, D Vertommen, M H Rider, À Navarro-Sabate, R Bartrons Tags: BJ Metabolism Source Type: research
The anti-inflammatory drug BAY 11-7082 suppresses the MyD88-dependent signaling network by targeting the ubiquitin system.
The compound BAY 11-7082 inhibits IκBα phosphorylation in cells and has been used to implicate the canonical IκB kinases (IKKs) and NFκB in <350 publications. Here we report that BAY 11-7082 does not inhibit the IKKs but suppresses their activation in LPS-stimulated RAW macrophages and IL-1-stimulated IL-1R HEK293 cells. BAY 11-7082 exerts these effects by inactivating the E2 conjugating enzymes Ubc13 and UbcH7 and the E3 ligase LUBAC (linear ubiquitin assembly complex), thereby preventing the formation of Lys63-linked and linear-polyubiquitin chains. BAY 11-7082 prevents ubiquitin conjugatio...
Source: BJ Signal - February 27, 2013 Category: Biochemistry Authors: S Strickson, D G Campbell, C H Emmerich, A Knebel, L Plater, M Stella Ritorto, N Shpiro, P Cohen Tags: BJ Signal Source Type: research
Pyrvinium pamoate does not activate protein kinase CK1, but promotes Akt/PKB down-regulation and GSK3 activation
It has been reported that Pyrvinium Pamoate (PyrPam), an FDA approved anthelminthic drug is a potent inhibitor of Wnt signaling by a mechanism which implies the direct activation of protein kinase CK1α. Here we present data ruling out any direct stimulatory effect of PyrPam on CK1, by showing that neither the catalytic activity of CK1α nor those of its isoforms δ and γ1 are significantly affected by PyrPam when tested with the aid of specific peptide and protein substrates. Accordingly, cell treatment with PyrPam has no significant effect on the phosphorylation of β-catenin Ser-45. By con...
Source: BJ Signal - February 26, 2013 Category: Biochemistry Authors: A Venerando, C Girardi, M Ruzzene, L A Pinna Tags: BJ Signal Source Type: research
Adenosine-binding motif mimicry and cellular effects of a thieno[2,3-d]pyrimidine-based chemical inhibitor of atypical protein kinase C isozymes
The atypical protein kinase C (aPKC) isoforms iota (ι) and zeta (ζ) play crucial roles in the formation and maintenance of cell polarity and represent attractive anti-oncogenic drug targets in Ras-dependent tumours. To date, few isoform-specific chemical biology tools are available to inhibit aPKC catalytic activity. Here we describe the identification and functional characterization of potent and selective thieno[2,3-d]pyrimidine-based chemical inhibitors of aPKCs. A crystal structure of human PKCiota kinase domain bound to a representative compound, CRT0066854, reveals the basis for potent and selective che...
Source: BJ Signal - February 18, 2013 Category: Biochemistry Authors: S Kjær, M Linch, A Purkiss, B Kostelecky, P P Knowles, C Rosse, P Riou, C Soudy, S Kaye, B Patel, E Soriano, J Murray-Rust, C Barton, C Dillon, J Roffey, P J Parker, N Q McDonald Tags: BJ ChemBio Source Type: research
A broad activity screen in support of a chemogenomic map for kinase signaling research and drug discovery
Despite the development of a number of efficacious kinase inhibitors, the strategies for rational design of these compounds have been limited by target promiscuity. In an effort to better understand the nature of kinase inhibition across the kinome, especially as it relates to off-target effects, we screened a well-defined collection of kinase inhibitors using biochemical assays for inhibitory activity against 234 active human kinases and kinase complexes, representing all branches of the kinome tree. For our study we employed 158 small molecules initially identified in the literature as potent and specific inhibitors of k...
Source: BJ Signal - February 12, 2013 Category: Biochemistry Authors: Y Gao, S P. Davies, M Augustin, A Woodward, U A. Patel, R Kovelman, K J. Harvey Tags: BJ Signal Source Type: research
Incretin-stimulated interaction between {beta}-cell Kv1.5 and Kv{beta}2 channel proteins involves acetylation/deacetylation by CBP/SirT1
The incretins, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are gastrointestinal hormones conferring a number of beneficial effects on β-cell secretion, survival and proliferation. In an earlier study, it was demonstrated that delayed rectifier channel protein Kv2.1 contributes to β-cell apoptosis and that prosurvival effects of incretins involve Kv2.1 post-translational modifications (PTMs), including phosphorylation and acetylation. Since Kv1.5 overexpression was also shown to stimulate β-cell death, the current study was initiated in order to determine wheth...
Source: BJ Signal - February 7, 2013 Category: Biochemistry Authors: S Kim, Z Ao, G Warnock, C H S McIntosh Tags: BJ Metabolism Source Type: research
Sox2 protects neural stem cells from apoptosis via up-regulating survivin expression
In this study, we found that Sox2 directly up-regulates the expression of survivin, which inhibits the mitochondria-dependent apoptotic pathway in NSCs. While over-expression of Sox2 elevates the survivin expression, knock-down of Sox2 results in a decrease in survivin expression, thereby initiating the mitochondria-dependent apoptosis related with caspase-9 activation. Furthermore, cell apoptosis due to Sox2 knock-down can be rescued by ectopically expressing survivin in NSCs as well as in the mouse brain, as demonstrated by an in utero-injection approach. In short, we have found a novel Sox2-survivin pathway that regulat...
Source: BJ Signal - January 10, 2013 Category: Biochemistry Authors: R Feng, S Zhou, Y Liu, D Song, Z Luan, X Dai, Y Li, N Tang, J Wen, L Li Tags: BJ Signal Source Type: research
gp130 activation is regulated by D2-D3 interdomain connectivity
Activation of the IL-6 receptor subunit gp130 has been linked to complex formation with IL-6 and the IL-6 receptor, as well as to gp130 dimerization. However, it has been shown that gp130 is present as pre-formed dimer, indicating that its activation is not solely dependent on dimerization. Therefore the detailed mechanism of gp130 activation still remains to be deciphered. Recently, deletion mutations of gp130 have been found in inflammatory hepatocellular adenoma. The mutations clustered around one IL-6 binding epitope of gp130 and resulted in a ligand-independent constitutively active gp130. We therefore hypothesized th...
Source: BJ Signal - January 7, 2013 Category: Biochemistry Authors: A Schütt, M Zacharias, N Schneider, S Horn, J Grötzinger, S Rose-John, D Schmidt-Arras Tags: BJ Signal Source Type: research
