Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.2 (focal adhesion kinase)
44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The migration of arterial vascular smooth muscle cells (VSMC) is thought to play a central role in atherogenesis and restenosis. The migration of several other cell types, including monocytes, T-lymphocytes and endothelial cells is also involved in the development of the mature atherosclerotic lesion. Several defined growth factors, cytokines and extracellular matrix components which are released at the sites of lesions have been implicated in the regulation of migration of VSMC and other lesion-associated cells. Platelet-derived growth factor BB-homodimer of PDGF (PDGF-BB) is strongly implicated in neo-intima formation in vivo and is the most potent known chemoattractant for VSMC in vitro. Dynamic interactions between cell surface adhesive receptors (integrins) for ECM components, organisation of the actin cytoskeleton and the turnover of focal adhesions are all key processes in cell locomotion and migration. The signal transduction pathways which mediate the chemotactic effects of PDGF-BB and other migration factors on VSMC are unknown, but several classes of cellular components are implicated including components associated with focal adhesions, small GTP-binding proteins of the rho family, and certain substrates of the PDGF beta-receptor. Tyrosine phosphorylation of the novel focal adhesion-associated protein tyrosine kinase, p125 focal adhesion kinase (p125FAK), is regulated by integrins and by several factors which alter actin cytoskeletal organisation. Recent findings suggest that tyrosine phosphorylation of p125FAK and other focal adhesion-associated proteins may be implicated in the chemotactic response of VSMC to PDGF-BB. The migratory response to PDGF-BB may be dependent on both ligand isoform bio-availability and on receptor-isotype expression as well as on down-stream signalling events. Ultimately, cell migration in vivo will be determined by a complex array of diverse extracellular molecules organised in intercellular paracrine/autocrine networks as well as multiple interacting intracellular signal transduction pathways.
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PMID:Signalling mechanisms in the regulation of vascular cell migration. 857 3

Endothelin-1 (ET-1) is known to induce the contraction and proliferation of glomerular mesangial cells. Because ET-1 was found to stimulate the tyrosine phosphorylation of unidentified cellular proteins in cultured mesangial cells, protein tyrosine kinase might serve as one of the important signals leading to various functions of ET-1. Focal adhesion kinase (p125FAK) is a newly identified cytoplasmic protein tyrosine kinase that is activated by the phosphorylation of its own tyrosine residue. Because p125FAK was found to play a role in the signal transduction of not only integrins but also various neurotransmitters, including bombesin, endothelin, and vasopressin in Swiss 3T3 cells and Rat-1 fibroblasts, whether ET-1 could stimulate the tyrosine phosphorylation of p125FAK in glomerular mesangial cells was examined. ET-1 stimulated the tyrosine phosphorylation of p125FAK by threefold to fourfold in cultured mesangial cells. This effect of ET-1 was detected at 1 min and reached a maximum within 5 min and was blocked by BQ-123, an antagonist for ETA receptor. A23187, a calcium ionophore, failed to stimulate the tyrosine phosphorylation of p125FAK, and ET-1 was able to stimulate the tyrosine phosphorylation of p125FAK, even in a calcium-free medium. The activation of protein kinase C (PKC) by phorbol 12, 13-dibutyrate resulted in a stimulation of the tyrosine phosphorylation of p125FAK, and an inhibition of PKC by calphostin C or staurosporine significantly reduced the effect of ET-1. Furthermore, prolonged treatment of the cells with phorbol 12, 13-dibutyrate markedly inhibited the ET-1-induced tyrosine phosphorylation of p125FAK. These results indicate that p125FAK might play a role in a signal transduction system of ET-1 in glomerular mesangial cells and that the ET-1-induced tyrosine phosphorylation of p125FAK is largely dependent on the PKC pathway.
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PMID:Endothelin-1 stimulates tyrosine phosphorylation of p125 focal adhesion kinase in mesangial cells. 858 30

Receptors for interferons and other cytokines signal through the action of associated protein tyrosine kinases of the JAK family and latent cytoplasmic transcription factors of the STAT family. Genetic and biochemical analysis of interferon signaling indicates that activation of STATs by interferons requires two distinct JAK family kinases. Loss of either of the required JAKs prevents activation of the other JAK and extinguishes STAT activation. These observations suggest that JAKs provide interferon receptors with a critical catalytic signaling function and that at least two JAKs must be incorporated into an active receptor complex. JAK and STAT proteins are also activated by ligands such as platelet-derived growth factor (PDGF), which act through receptors that possess intrinsic protein tyrosine kinase activity, raising questions about the role of JAKs in signal transduction by this class of receptors. Here, we show that all three of the ubiquitously expressed JAKs--JAK1, JAK2, and Tyk2--become phosphorylated on tyrosine in both mouse BALB/c 3T3 cells and human fibroblasts engineered to express the PDGF-beta receptor. All three proteins are also associated with the activated receptor. Through the use of cell lines each lacking an individual JAK, we find that in contrast to interferon signaling, PDGF-induced JAK phosphorylation and activation of STAT1 and STAT3 is independent of the presence of any other single JAK but does require receptor tyrosine kinase activity. These results suggests that the mechanism of JAK activation and JAK function in signaling differs between receptor tyrosine kinases and interferon receptors.
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PMID:Platelet-derived growth factor induces phosphorylation of multiple JAK family kinases and STAT proteins. 865 51

The zeta polypeptide is part of the T cell antigen receptor (TCR). The zeta-chain contributes to efficient cell-surface expression of the TCR and accounts for part of its signal transduction capability. TCR recognition triggers a complex set of events that result in cellular activation. The protein tyrosine kinase (PTK) Lck phosphorylates the zeta-chain, which in turn associates with another PTK, ZAP70, and stimulates its phosphorylation activity. Here we report the expression of the intracellular part of the zeta-chain and its biochemical characterization. The recombinant protein does not dimerize by itself in solution. Circular-dichroic analysis reveals a random coil conformation. zeta, phosphorylated using recombinant Lck, associates with recombinant ZAP70 tandem-SH2 domains. All three T cell activation motifs in zeta bind ZAP70 tandem-SH2 domains in vitro, forming a 1:3 complex. This result extends the picture, derived from earlier studies, of a mechanism for signal amplification.
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PMID:Phosphorylated T cell receptor zeta-chain and ZAP70 tandem SH2 domains form a 1:3 complex in vitro. 868 56

Bruton's tyrosine kinase (BTK) is a member of the SRC-related TEC family of protein tyrosine kinases (PTKs). DT-40 lymphoma B cells, rendered BTK-deficient through targeted disruption of the btk gene by homologous recombination knockout, did not undergo radiation-induced apoptosis, but cells with disrupted lyn or syk genes did. Introduction of the wild-type, or a SRC homology 2 domain or a plecstrin homology domain mutant (but not a kinase domain mutant), human btk gene into BTK-deficient cells restored the apoptotic response to radiation. Thus, BTK is the PTK responsible for triggering radiation-induced apoptosis of lymphoma B cells, and its kinase domain is indispensable for the apoptotic response.
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PMID:BTK as a mediator of radiation-induced apoptosis in DT-40 lymphoma B cells. 868 94

Small cell lung cancer (SCLC) cell growth is sustained by multiple autocrine and paracrine growth loops involving neuropeptides. The bombesin family of peptides are autocrine growth factors in H345 SCLC cells and provide a paradigm for the study of growth factors and mitogenic signaling in SCLC cells. We show that bombesin (and other neuropeptides) stimulates protein tyrosine phosphorylation (particularly focal adhesion kinase) and protein tyrosine kinase (PTK) activity in intact SCLC cells. Furthermore, the broad spectrum neuropeptide receptor antagonist [D-Arg, D = Phe, D-Trp, Leu11]substance P inhibits all neuropeptide-mediated signals (including PTK activation), SCLC cell growth in vivo and in vitro, and also increases the natural rate of apoptosis seen in growing SCLC cell lines. Hence the effect of selective PTK inhibition on SCLC cell growth and apoptosis was examined. We show that selective inhibition of PTK activity, with genistein and (3,4,5-tri-hydroxyphenyl)-methylene(-propanedinitrile) tyrphostin-25 inhibits basal and neuropeptide-stimulated SCLC cell growth. Genistein and tyrphostin-25 also stimulate apoptosis in SCLC cells. Inhibition of proliferation in these cells is intimately linke to apoptosis, because these changes occurred without any effect on SCLC cell cycle kinetics, suggesting that apoptosis occurs independently of the cell cycle and that failure to progress through the cell cycle results in apoptosis. Because tyrphostin-25 fails to influence p53 or Bcl-2 expression in these cells, this mode of programmed cell death appears to be via a p53- and Bcl-2-independent mechanism. These results provide evidence that tyrosine phosphorylation is a mitogenic signal in SCLC cells and suggest that regulation of the level of protein tyrosine phosphorylation represents a critical determinant of whether SCLC cells survive and proliferate or die by apoptosis. Thus PTK inhibition may provide a novel therapeutic option in SCLC that has become resistant to conventional chemotherapeutic agents.
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PMID:Inhibition of neuropeptide-stimulated tyrosine phosphorylation and tyrosine kinase activity stimulates apoptosis in small cell lung cancer cells. 879 1

Stimulation of small cell lung cancer (SCLC) cells with neuropeptides bombesin, bradykinin, gastrin, and neurotensin resulted in increased tyrosine kinase activity and tyrosine phosphorylation of a number of polypeptides including a p120 kDa polypeptide identified by immunoblotting as focal adhesion kinase (p125FAK). The neuropeptides stimulated a rapid, concentration-dependent phosphorylation of p125FAK (EC50 of 1 nM, 5 nM, and 2 nM for bombesin, bradykinin, and gastrin, respectively), which was receptor mediated and inhibited by both specific and broad-spectrum neuropeptide receptor antagonists. Specific inhibition of protein tyrosine kinase activity by tyrphostin-25 inhibited both basal and neuropeptide-stimulated SCLC cell growth. These results identify a novel neuropeptide-stimulated growth signaling event in SCLC cells.
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PMID:Neuropeptides stimulate tyrosine phosphorylation and tyrosine kinase activity in small cell lung cancer cell lines. 880 78

Neurotoxicity of the amyloid beta protein (A beta) is known to correlate with a selective change in protein tyrosine phosphorylation (Tyr(P)) of focal adhesion kinase (FAK) (Zhang et al., J. Biol. Chem., 269 (1994) 25247-25250). The current work has found that exposure of neuronal cells to A beta upregulates the stable association of FAK with Fyn, a neuronally-enriched protein tyrosine kinase of the Src-family. In cells incubated with aged A beta 1-42, the amount of immunoprecipitable FAK-Fyn complex increased approximately 280%. Equivalent results were obtained whether anti-FAK or anti-Fyn was used to precipitate the complex. Cells incubated with non-toxic A beta 17-42, which makes aggregates and attaches to cells but does not upregulate FAK Tyr(P), exhibited no increase in FAK-Fyn complex. Aberrant Fyn activity due to the A beta evoked association with FAK could play a role in neuronal degeneration and also cause anomalies in synaptic plasticity. These possibilities are of particular significance because of the reported increase in Fyn immunoreactivity in Alzheimer's-afflicted neurons (Shirazi and Wood, NeuroReport, 4 (1993) 435-437).
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PMID:A beta peptide enhances focal adhesion kinase/Fyn association in a rat CNS nerve cell line. 881 72

Focal adhesion kinase (pp125FAK) is a nonreceptor protein tyrosine kinase transducing signals initiated through integrin activation triggered by cell/extracellular matrix (ECM) interactions. To examine its role in epithelial cell adhesion, proliferation, and differentiation, we have studied pp125FAK expression, activity, and association with paxillin in two canine prostate models in which these functions can be selectively regulated: in vitro by vitronectin (VN) and serum factors, and in vivo by sex steroids. Kinetic studies revealed that the adhesion and spreading of prostatic epithelial cells in primary culture was regulated by serum VN and a natural ECM containing VN produced by prostate cells. While barely detectable in freshly isolated prostate cells, proliferating cells, after 72 h in culture, expressed higher levels of FAK mRNA (8-fold), pp125FAK (50-fold), and paxillin (50-fold). In prostate cells with a reduced growth rate after 2 weeks in culture, we observed a decrease in pp125FAK (4-fold) and its transcript (3-fold), but no change in paxillin. In vivo, both proteins were undetectable in normal and hyperplastic glands composed of a well differentiated epithelium, and in prostates restored by androgen supplementation. In contrast, pp125FAK and paxillin were up-regulated by androgen deprivation (castration) and further increased by estrogen treatment, which yielded metaplastic prostates mostly composed of proliferating basal epithelial cells. Moreover, both proteins were constitutively phosphorylated on tyrosine in the metaplastic prostate, as well as in proliferating cultured cells. Together, these results demonstrate that pp125FAK expression is regulated at the protein and mRNA levels and forms active signaling complexes with paxillin when epithelial cells in contact with ECM proteins are induced to proliferate in vivo and in vitro.
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PMID:Regulation and activation of focal adhesion kinase and paxillin during the adhesion, proliferation, and differentiation of prostatic epithelial cells in vitro and in vivo. 884 17

Here we show that exposure of human B-cell precursors to gamma-rays stimulates the enzymatic activity of the Src protooncogene family protein tyrosine kinase LYN. LYN activation in irradiated cells is not triggered by DNA damage or a nuclear signal since gamma-rays effectively stimulated LYN kinase in enucleated B-cell precursors as well. LYN activation in irradiated cells was abrogated by presence of the OH* radical scavenger dimethylsulfoxide and exposure of intact or enucleated B-cell precursors to chemically generated OH* radicals instead of gamma-rays also triggered LYN kinase activation and enhanced tyrosine phosphorylation of multiple electrophoretically distinct protein substrates. Thus, OH* radicals appear to be both mandatory and sufficient for radiation-induced LYN kinase activation in irradiated B-cell precursors. We further present evidence which indicates that OH* radicals activate LYN by a novel mechanism which involves disruption of inactive LYN-LYN homodimers and monomerization of the LYN kinase after proteolytic degradation of a putative LYN-associated adapter protein through a cytoplasmic TPCK-sensitive chymotrypsin-like protease following its oxidation. LYN kinase plays a pivotal role in initiation of signal cascades that affect the proliferation, differentiation, and survival of B-cell precursors. Our results prompt the hypothesis that a growth regulatory balance might be altered in human B-cell precursors by radiation-induced stimulation of LYN kinase.
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PMID:Role of hydroxyl radicals in radiation-induced activation of lyn tyrosine kinase in human B-cell precursors. 888 55


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