Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.10.2 (focal adhesion kinase)
 44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human RIN1 was first characterized as a RAS binding protein based on the properties of its carboxyl-terminal domain. We now show that full-length RIN1 interacts with activated RAS in mammalian cells and defines a minimum region of 434 aa required for efficient RAS binding. RIN1 interacts with the "effector domain" of RAS and employs some RAS determinants that are common to, and others that are distinct from, those required for the binding of RAF1, a known RAS effector. The same domain of RIN1 that binds RAS also interacts with 14-3-3 proteins, extending the similarity between RIN1 and other RAS effectors. When expressed in mammalian cells, the RAS binding domain of RIN1 can act as a dominant negative signal transduction blocker. The amino-terminal domain of RIN1 contains a proline-rich sequence similar to consensus Src homology 3 (SH3) binding regions. This RIN1 sequence shows preferential binding to the ABL-SH3 domain in vitro. Moreover, the amino-terminal domain of RIN1 directly associates with, and is tyrosine phosphorylated by, c-ABL. In addition, RIN1 encodes a functional SH2 domain that has the potential to activate downstream signals. These data suggest that RIN1 is able to mediate multiple signals. A differential pattern of expression and alternate splicing indicate several levels of RIN1 regulation.
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PMID:Protein binding and signaling properties of RIN1 suggest a unique effector function. 914 71

The middle tumor antigen (middle-T) of mouse polyomavirus is responsible for the transforming potential of this virus. Middle-T has been shown to interact with a variety of cellular proteins known to mediate mitogenic signaling, like phosphatase-2A, Src family kinases, phosphatidylinositol 3-kinase (PI 3-kinase), the adapter protein SHC, phospholipase Cgamma-1 and 14-3-3 family proteins. Association with SHC and PI 3-kinase, respectively, stimulates two independent signaling pathways that are indispensible for viral oncogenicity. SHC activates the Ras/MAPK pathway via Grb2/SOS resulting in changes in early gene expression. The downstream targets of PI 3-kinase are less well studied but seem to impinge on serum response factor (SRF) which is also involved in regulating early gene expression. Recently, the protein kinase B/Akt (PKB/Akt) has been identified as a target of PI 3-kinase in receptor tyrosine kinase signaling. Here we show that PKB/Akt is a target of wild type middle-T, but not of mutants unable to activate PI 3-kinase. These data were confirmed using inhibitors of PI 3-kinase as well as dominant-negative alleles of the catalytic subunit of this lipid kinase. In addition, mutants of PKB/Akt lacking a pleckstrin homology domain and therefore unable to bind to D3 phospatidylinositides were not activated by middle-T. Taken together these data suggest that middle-T activates PKB/Akt in a PI 3-kinase-dependent manner. Furthermore, direct association with D3 phosphatidylinositides seems to be essential for activation of PKB/Akt.
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PMID:Protein kinase B/Akt is activated by polyomavirus middle-T antigen via a phosphatidylinositol 3-kinase-dependent mechanism. 948 81

Ras-mediated signaling pathways play a critical role in cellular proliferation and differentiation. Although it has been demonstrated that Ras interacts with Raf-1 to stimulate the serine/threonine kinase activity of Raf-1, the precise mechanism by which Ras activates Raf-1 remains obscure. To address this question, we developed a cell-free system in which the activated form of H-Ras can induce Raf-1 activation. Using this system, we found the presence of a new protein factor, in cytosolic fractions of both human embryonic kidney 293 cells and rat brain tissues, that is required for Ras-dependent activation of Raf-1. The factor was purified from rat brain cytosols through successive column chromatographies on DEAE Sephacel, SP Sepharose and Sephacryl S-300. The approximate molecular weight of the activator was estimated as 400,000 by gel filtration. Its activity was sensitive to heat and trypsin treatments. The purified activator did not contain Src, 14-3-3, protein kinase C, JAK2 or Ksr-1, as judged by immunoblotting. Further characterization of the activator is underway.
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PMID:Isolation of a new protein factor required for activation of Raf-1 by Ha-Ras: partial purification from rat brain cytosols. 965 45

The protection against apoptosis provided by growth factors in several cell lines is due to stimulation of the phosphatidylinositol-3-OH kinase (PI(3)K) pathway, which results in activation of protein kinase B (PKB; also known as c-Akt and Rac) and phosphorylation and sequestration to protein 14-3-3 of the proapoptotic Bcl-2-family member BAD. A modest increase in intracellular Ca2+ concentration also promotes survival of some cultured neurons through a pathway that requires calmodulin but is independent of PI(3)K and the MAP kinases. Here we report that Ca2+/calmodulin-dependent protein kinase kinase (CaM-KK) activates PKB directly, resulting in phosphorylation of BAD on serine residue 136 and the interaction of BAD with protein 14-3-3. Serum withdrawal induced a three- to fourfold increase in cell death of NG108 neuroblastoma cells, and this apoptosis was largely blocked by increasing the intracellular Ca2+ concentration with NMDA (N-methyl-D-aspartate) or KCl or by transfection with constitutively active CaM-KK. The effect of NMDA on cell survival was blocked by transfection with dominant-negative forms of CaM-KK or PKB. These results identify a Ca2+-triggered signalling cascade in which CaM-KK activates PKB, which in turn phosphorylates BAD and protects cells from apoptosis.
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PMID:Calcium promotes cell survival through CaM-K kinase activation of the protein-kinase-B pathway. 985 94

The function of the pro-apoptotic molecule BAD is regulated by phosphorylation of two sites, serine-112 (Ser-112) and serine-136 (Ser-136). Phosphorylation at either site results in loss of the ability of BAD to heterodimerize with the survival proteins BCL-XL or BCL-2. Phosphorylated BAD binds to 14-3-3 and is sequestered in the cytoplasm. It has been shown that phosphorylation of BAD at Ser-136 is mediated by the serine/threonine protein kinase Akt-1/PKB which is downstream of phosphatidylinositol 3-kinase (PI3K). The signaling process leading to phophorylation of BAD at Ser-112 has not been identified. In this study, we show that phosphorylation of the two serine residues of BAD is differentially regulated. While Ser-136 phosphorylation is concordant with activation of Akt, Ser-112 phosphorylation does not correlate with Akt activation. Instead, we demonstrate that activated Ras and Raf, which are upstream of mitogen-activated protein kinases (MAPK), stimulate selective phosphorylation of BAD at Ser-112. Furthermore, phosphorylation of Ser-112, but not Ser-136 requires activation of the MAPK pathway as the MEK inhibitor, PD 98059, blocks EGF-, as well as activated Ras- or Raf-mediated phosphorylation of BAD at Ser-112. Therefore, the PI3K-Akt and Ras-MAPK pathways converge at BAD by mediating phosphorylation of distinct serine residues.
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PMID:Regulation of BAD phosphorylation at serine 112 by the Ras-mitogen-activated protein kinase pathway. 1059 68

The interaction of BAD (Bcl-2/Bcl-X(L)-antagonist, causing cell death) with Bcl-2/Bcl-X(L) is thought to neutralize the anti-apoptotic effects of the latter proteins, and may represent one of the mechanisms by which BAD promotes apoptosis. A variety of survival signals are reported to induce the phosphorylation of BAD at Ser(112) or Ser(136), triggering its dissociation from Bcl-2/Bcl-X(L). Ser(136) is thought to be phosphorylated by protein kinase B (PKB, also called Akt), which is activated when cells are exposed to agonists that stimulate phosphatidylinositol 3-kinase (PI3K). In contrast, Ser(112) is reported to be phosphorylated by mitogen-activated protein (MAP) kinase-activated protein kinase-1 (MAPKAP-K1, also called RSK) and by cAMP-dependent protein kinase (PKA). Here we identify Ser(155) as a third phosphorylation site on BAD. We find that Ser(155) is phosphorylated preferentially by PKA in vitro and is the only residue in BAD that becomes phosphorylated when cells are exposed to cAMP-elevating agents. The phosphorylation of BAD at Ser(155) prevents it from binding to Bcl-X(L) and promotes its interaction with 14-3-3 proteins. We also provide further evidence that MAPKAP-K1 mediates the phosphorylation of Ser(112) in response to agonists that activate the classical MAP kinase pathway. However insulin-like growth factor 1, a potent activator of PI3K and PKB does not increase the phosphorylation of Ser(136) in BAD-transfected HEK-293 cells, and nor is the basal level of Ser(136) phosphorylation suppressed by inhibitors of PI3K.
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PMID:Regulation of BAD by cAMP-dependent protein kinase is mediated via phosphorylation of a novel site, Ser155. 1088 Mar 54

The activation of cell cycle checkpoints in response to genotoxic stressors is essential for the maintenance of genomic integrity. Although most prior studies of cell cycle effects of UV irradiation have used UVC, this UV range does not penetrate the earth's atmosphere. Thus, we have investigated the mechanisms of ultraviolet B (UVB) irradiation-induced cell cycle arrest in a biologically relevant target cell type, the early stage human melanoma cell line, WM35. Irradiation of WM35 cells with UVB resulted in arrests throughout the cell cycle: at the G1/S transition, in S phase and in G2. G1 arrest was accompanied by increased association of p21 with cyclin E/cdk2 and cyclin A/cdk2, increased binding of p27 to cyclin E/cdk2 and inhibition of these kinases. A loss of Cdc25A expression was associated with an increased inhibitory phosphotyrosine content of cyclin E- and cyclin A-associated cdk2 and may also contribute to G1 arrest following UVB irradiation. The association of Cdc25A with 14-3-3 was increased by UVB. Reduced cyclin D1 protein and increased binding of p21 and p27 to cyclin D1/cdk4 complexes were also observed. The loss of cyclin D1 could not be attributed to inhibition of either MAPK or PI3K/PKB pathways, since both were activated by UVB. Cdc25B levels fell and the remaining protein showed an increased association with 14-3-3 in response to UVB. Losses in cyclin B1 expression and an increased binding of p21 to cyclin B1/cdk1 complexes also contributed to inhibition of this kinase activity, and G2/M arrest. Oncogene (2000) 19, 4480 - 4490.
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PMID:UVB induced cell cycle checkpoints in an early stage human melanoma line, WM35. 1100 21

Integrins are cell surface receptors for extracellular matrix, which play important roles in a variety of biological processes. 14-3-3 proteins are a highly conserved family of cytoplasmic proteins that associate with several intracellular signaling molecules in regulation of various cellular functions. Here, we report identification of an interaction between the integrin beta1 cytoplasmic domain and 14-3-3beta by using the yeast two-hybrid screen. Like several other proteins, the integrin beta1 cytoplasmic domain associated with 14-3-3beta by a non-phosphoserine mechanism. The 14-3-3beta/integrin beta1 interaction was confirmed by in vitro binding assays as well as co-precipitation in vivo. Furthermore, we found that 14-3-3beta co-localized with integrin beta1 during the early stage of cell spreading on fibronectin, suggesting a potential role of the 14-3-3beta/integrin beta1 interaction in the regulation of cell adhesion. Using tetracycline-regulated expression system, we showed that overexpression of 14-3-3beta stimulated cell spreading and migration on fibronectin but not on poly-L-lysine. However, the induced expression of 14-3-3beta did not affect tyrosine phosphorylation of FAK or its substrates, p130(cas) and paxillin, suggesting that 14-3-3beta regulated integrin-mediated cell spreading and migration by FAK-independent mechanisms. Taken together, these results identify an interaction between integrin and 14-3-3 proteins and suggest a potentially novel cellular function for 14-3-3 proteins in the regulation of integrin-mediated cell adhesion and signaling events.
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PMID:Identification of a novel interaction between integrin beta1 and 14-3-3beta. 1131 64

The alkylating agent methylmethanesulfonate (MMS) activates the c-jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPK) and the p38 mitogen-activated protein kinase (p38MAPK) pathways via different mechanisms of action. Activation of p38MAPK by MMS involves the pp125 focal adhesion kinase-related tyrosine kinase RAFTK and the MAPK kinase 3. The way in which MMS can activate JNK/SAPK has not been elucidated. Here we describe the identification by differential display of human mitogen-activated gene-6 (MIG-6) as a novel MMS-inducible gene. Induction of MIG-6 by MMS was found in human diploid skin fibroblasts and in simian virus 40-transformed skin fibroblasts, indicating that the enhanced expression of MIG-6 after MMS-treatment did not require p53. The signal leading to activation of MIG-6 appeared to be independent of DNA damage. High MIG-6 expression was found in the liver, lung, and placenta. MIG-6 is an adapter protein that binds to the activated form of cdc42Hs and to 14-3-3 proteins, thereby activating JNK/SAPKs. Our results suggest that activation of JNK/SAPKs by MMS may involve the induction of MIG-6.
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PMID:Induction of the SAPK activator MIG-6 by the alkylating agent methyl methanesulfonate. 1142 82

Protein kinase B/Akt (PKB/Akt) is a member of the ACG kinase family, which also includes protein kinase C, that phosphorylates a number of 14-3-3-binding proteins. 14-3-3 protein regulation of protein kinase C activity is modulated by 14-3-3 phosphorylation. We examined the hypothesis that PKB/Akt interacts with and phosphorylates 14-3-3zeta, leading to modulation of dimerization. By glutathione S-transferase pull-down, Akt precipitated recombinant 14-3-3zeta and endogenous 14-3-3zeta from HEK293 cell lysates. Recombinant active PKB/Akt phosphorylated recombinant 14-3-3zeta in an in vitro kinase assay. Transfection of active PKB/Akt into HEK293 cells resulted in phosphorylation of 14-3-3zeta. Based on a motif search of 14-3-3zeta, a potential PKB/Akt phosphorylation site, Ser-58, was mutated to alanine. PKB/Akt was unable to phosphorylate this mutant protein. Incubation of 14-3-3zeta with recombinant active PKB/Akt resulted in phosphorylation of 45% of the protein, as determined by a pI shift on two-dimensional electrophoresis, but 14-3-3zeta dimerization was not altered. These data indicate that PKB/Akt phosphorylates Ser-58 on 14-3-3zeta both in vitro and in intact cells. The functional relevance of this phosphorylation remains to be determined.
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PMID:Identification of 14-3-3zeta as a protein kinase B/Akt substrate. 1195 22


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