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

---

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

We and others have recently cloned a non-receptor, calcium-dependent tyrosine kinase (CADTK; also known as PYK2, CAKbeta, and RAFTK) that shares both overall domain structure and 45% amino acid identity with p125(FAK). We have studied the signaling, activation, and potential function of these related enzymes in GN4 rat liver epithelial cells that express CADTK and p125(FAK) at roughly similar levels. p125(FAK) is nearly fully tyrosine-phosphorylated in resting GN4 cells. In contrast, while CADTK is not tyrosine-autophosphorylated in untreated cells, angiotensin II increases CADTK Tyr(P) by 5-10-fold. With regard to signaling, CADTK activation is correlated with stimulation of c-Jun N-terminal kinase and p70(S6K) pathways but not with the stimulation of mitogen-activated protein kinase or p90(RSK). In this report we assessed the contribution of CADTK and p125(FAK) to tyrosine phosphorylation of focal contact proteins. In adherent GN4 cells, the constitutive activity of p125(FAK) was correlated with basal paxillin, tensin, and p130(CAS) tyrosine phosphorylation. A rapid increase in the tyrosine phosphorylation of each protein was detected after treatment with angiotensin II or other agonists that stimulate CADTK; the prolonged 3-4-fold increase in paxillin tyrosine phosphorylation was the most substantial change. In the WB cell line that expresses 3-fold less CADTK than GN4 cell line agonist-dependent paxillin tyrosine phosphorylation is similarly reduced. Immunoprecipitation of CADTK from GN4 cells revealed CADTK. paxillin complexes that persisted in 500 mM NaCl but not in 0.1% SDS cell lysis buffer. The complexes were largely independent of the tyrosine phosphorylation state of either protein. Surprisingly, we did not detect p125(FAK).paxillin complexes in immunoprecipitates using either of two p125(FAK) antibodies. When CADTK and p125(FAK) were transiently overexpressed in 293(T) cells, both enzymes associated with paxillin, but the avidity of CADTK appeared to be greater. In addition, in transfected 293(T) cells, complexes between CADTK and another potential substrate, p130(CAS), were detected. In summary, in GN4 rat liver epithelial cells stimulation of CADTK was highly correlated with paxillin tyrosine phosphorylation; in addition, CADTK but not p125(FAK) was complexed to paxillin at detectable levels. This suggests that agonist-dependent cytoskeletal changes in epithelial cells might proceed, in part, by CADTK-dependent mechanisms.
...
PMID:Paxillin is tyrosine-phosphorylated by and preferentially associates with the calcium-dependent tyrosine kinase in rat liver epithelial cells. 916 70

Focal adhesion kinase (pp125(FAK)) is a protein tyrosine kinase that is localized to focal adhesions in many cell types and which undergoes tyrosine phosphorylation after integrin binding to extracellular matrix. In some cells the C-terminal non-catalytic domain of pp125(FAK) is expressed as a separate protein referred to as FRNK (FAK-related, non-kinase). We have previously shown that overexpression of FRNK inhibits tyrosine phosphorylation of pp125(FAK) and its substrates as well as inhibiting cell spreading on fibronectin. In this report we identify Ser148 and Ser151 as residues in FRNK that are phosphorylated after tyrosine phosphorylation of pp125(FAK) and in response to integrin binding to fibronectin. Tyrosine phosphorylation of pp125(FAK) appears to be an early event after integrin occupancy, and serine phosphorylation of FRNK occurs significantly later. Treatment of fibroblasts with a series of protein kinase A inhibitors delayed serine phosphorylation of FRNK as well as cell spreading on fibronectin and tyrosine phosphorylation of pp125(FAK). However, these PKA inhibitors are unlikely to delay cell spreading simply by preventing serine phosphorylation of FRNK, as overexpression of FRNK containing mutations of Ser148 and Ser151 either singly or jointly to either alanine or glutamate residues did not significantly alter the ability of FRNK to act as an inhibitor of pp125(FAK).
...
PMID:Identification of integrin-stimulated sites of serine phosphorylation in FRNK, the separately expressed C-terminal domain of focal adhesion kinase: a potential role for protein kinase A. 916 50

Integrin-associated protein (IAP or CD47) is a receptor for the cell/platelet-binding domain (CBD) of thrombospondin-1 (TS1), the most abundant protein of platelet alpha granules. Although it associates with alphaIIbbeta3, IAP has no known function in platelets. TS1, the CBD, and an IAP agonist peptide (4N1K) from the CBD of TS1 activate the platelet integrin alphaIIbbeta3, resulting in platelet spreading on immobilized fibrinogen, stimulation of platelet aggregation, and enhanced tyrosine phosphorylation of focal adhesion kinase. Furthermore, 4N1K peptide selectively stimulates the phosphorylation of LYN and SYK and their association with FAK. The phosphorylation of SYK is blocked by pertussis toxin, implicating a Gi-like heterotrimeric G protein. IAP solublized from membranes of unstimulated platelets binds specifically to an affinity column of 4N1K peptide. Both alphaIIb and beta3 integrin subunits and c-Src bind along with IAP. This complex of proteins is also detected with immunoprecipitation. Activation of platelets with the agonist peptide 4N1K results in the association of FAK with the IAP-alphaIIbbeta3 complex. Thus an important function of TS1 in platelets is that of a secreted costimulator of alphaIIbbeta3 whose unique properties result in its localization to the platelet surface and the fibrin clot.
...
PMID:Thrombspondin acts via integrin-associated protein to activate the platelet integrin alphaIIbbeta3. 916 39

Pathogenic Yersinia resist uptake by eukaryotic cells by a mechanism involving the virulence protein YopH, a protein tyrosine phosphatase. We show that p130Cas and FAK are phosphorylated and recruited to peripheral focal complexes during bacterial uptake in HeLa cells. The inactive form of YopH interacts with the tyrosine phosphorylated forms of FAK and p130Cas and co-localizes with these proteins in focal adhesions. On the other hand, the presence of active YopH results in inhibition of uptake, dephosphorylation of p130Cas and FAK, and disruption of peripheral focal complexes. We suggest that p130Cas and FAK are substrates for YopH and that the dephosphorylation of these proteins impairs the uptake of Yersinia pseudotuberculosis into HeLa cells.
...
PMID:The PTPase YopH inhibits uptake of Yersinia, tyrosine phosphorylation of p130Cas and FAK, and the associated accumulation of these proteins in peripheral focal adhesions. 917 45

Vascular endothelial growth factor (VEGF) stimulated the tyrosine phosphorylation of multiple components in confluent human umbilical vein endothelial cells (HUVECs) including bands of Mr 205,000, corresponding to the VEGF receptors Flt-1 and KDR, and Mr 145,000, 120,000, 97,000, and 65,000-70,000. VEGF caused a striking and transient increase in mitogen-activated protein (MAP) kinase activity and stimulated phospholipase C-gamma tyrosine phosphorylation, but it had no effect on phosphatidylinositol 3'-kinase activity. VEGF caused a marked increase in tyrosine phosphorylation of p125 focal adhesion kinase (p125(FAK)), which was both rapid and concentration-dependent. VEGF produced similar effects on p125(FAK) in the endothelial cell line ECV.304. VEGF stimulated tyrosine phosphorylation of the 68-kDa focal adhesion-associated component, paxillin, with similar kinetics and concentration dependence to that for p125(FAK). Thrombin and the phorbol ester, phorbol 12-myristate 13-acetate, also increased p125(FAK) tyrosine phosphorylation in HUVECs. The effect of VEGF on p125(FAK) tyrosine phosphorylation was completely inhibited by the actin filament-disrupting agent cytochalasin D and was partially inhibited by the protein kinase C inhibitor GF109203X. Inhibition of the MAP kinase pathway using a specific inhibitor of MAP kinase kinase had no effect on p125(FAK) tyrosine phosphorylation. VEGF stimulated migration and actin stress fiber formation in confluent HUVEC, and VEGF-induced p125(FAK)/paxillin tyrosine phosphorylation was accompanied by increased immunofluorescent staining of p125(FAK), paxillin, and phosphotyrosine in focal adhesions in confluent cultures of HUVECs. These findings identify p125(FAK) and paxillin as components in a VEGF-stimulated signaling pathway and suggest a novel mechanism for VEGF regulation of endothelial cell functions.
...
PMID:Vascular endothelial growth factor stimulates tyrosine phosphorylation and recruitment to new focal adhesions of focal adhesion kinase and paxillin in endothelial cells. 918 76

Sphingosine 1-phosphate (SPP), a sphingolipid second messenger implicated in the mitogenic action of platelet-derived growth factor [Olivera, A. and Spiegel, S. (1993) Nature (London) 365, 557-560], induced rapid reorganization of the actin cytoskeleton resulting in stress-fibre formation. SPP also induced transient tyrosine phosphorylation of focal adhesion kinase (p125(FAK)), a cytosolic tyrosine kinase that localizes in focal adhesions, and of the cytoskeleton-associated protein paxillin. Exoenzyme C3 transferase, which ADP-ribosylates Rho (a Ras-related small GTP binding protein) on asparagine-41 and renders it biologically inactive, inhibited both stress-fibre formation and protein tyrosine phosphorylation induced by SPP. Thus Rho may be an upstream regulator of both stress-fibre formation and tyrosine phosphorylation of p125(FAK) and paxillin. Pretreatment with PMA, an activator of protein kinase C (PKC), inhibited the stimulation of stress-fibre formation induced by 1-oleoyl-lysophosphatidic acid (LPA) but not that by SPP. Similarly, PMA also decreased LPA-induced tyrosine phosphorylation of p125(FAK) and paxillin without abrogating the response to SPP. Thus PKC is involved in LPA- but not SPP-dependent signalling. The polyanionic drug suramin, a broad-specificity inhibitor of ligand-receptor interactions, did not inhibit either the mitogenic effect of SPP or its stimulation of tyrosine phosphorylation of p125(FAK). However, suramin markedly inhibited these responses induced by LPA. These results suggest that in contrast with LPA, SPP may be acting intracellularly in Swiss 3T3 fibroblasts to stimulate tyrosine phosphorylation of p125(FAK) and paxillin and cell growth.
...
PMID:Sphingosine 1-phosphate stimulates rho-mediated tyrosine phosphorylation of focal adhesion kinase and paxillin in Swiss 3T3 fibroblasts. 918 7

Cell adhesive interactions play important roles during many normal physiological processes such as embryonic development and wound repair, and also during the progression of diseases such as cancer. Cell adhesion is mediated by the specific interactions of cell surface receptors with extracellular glycoproteins. The best characterized cell adhesion receptors are the integrins. Integrins comprise a family of more than 23 noncovalent, heterodimeric complexes consisting of an alpha and a beta subunit. Each subunit is a glycoprotein with a large, globular extracellular domain and a transmembrane domain. Most integrins have relatively small cytoplasmic domains consisting of fewer than 60 amino acids. Although many integrins can bind fibronectin, the alpha 5, beta 1, integrin is the major fibronectin receptor on most cells. This integrin mediates such cellular responses to fibronectin substrates as adhesion, migration, assembly of extracellular matrix, and signal transduction. Integrin ligands, such as fibronectin, are not passive adhesive molecules but are active participants in the cell adhesive process that leads to signal transduction. The best characterized integrin ligand is fibronectin. Fibronectin is a multifunctional glycoprotein comprised of three different types of homologous repeating units (termed type I, type II, and type III). Fibronectin has at least two independent cell adhesive regions: one located near the center of the polypeptide chain in the ninth and tenth type III modules binds to the alpha 5 beta 1 integrin. The biological function of the central cell adhesive region requires two critical amino acid sequences--an Arg-Gly-Asp (RGD) sequence and a Pro-His-Ser-Arg-Asn (PHSRN) sequence, which function in synergy--for optimal binding to the alpha 5 beta 1 integrin. Furthermore, the spacing between the crucial RGD and PHSRN sequences is also important for activity, suggesting the sequences themselves are necessary, but not sufficient, to account for the cell adhesive activity of fibronectin. One of the manifestations of integrin-mediated signal transduction including protein tyrosine phosphorylation. One cytoplasmic protein that is phosphorylated in response to cell adhesion is the focal adhesion kinase known as pp125FAK or FAK. The beta 1, beta 3, and beta 5 integrin intracellular domains are sufficient to initiate signal transduction pathways. Furthermore, alternative splicing can regulate the ability of beta integrin intracellular domains to participate in signal transduction. Other intracellular responses to cell adhesion include stimulation of migration, the assembly of an F-actin cytoskeleton and specialized structures called focal contacts, changes of cytoplasmic pH and calcium ion concentration, and modulation of proliferation and gene expression. Such varied modes of signal transduction are probably differentially controlled by a mechanism that requires either integrin receptor clustering alone, ligand occupancy in addition to clustering, or clustering and/or ligand occupancy plus tyrosine kinase activity for different responses. The examination of the fundamental mechanisms important for adhesion of cultured human cells and the resultant signaling processes has the potential of providing an understanding of molecular mechanisms involved in complex physiological processes and serving the basis for the development of novel therapeutic agents for the treatment of human disease.
...
PMID:Integrins in cell adhesion and signaling. 918 47

We propose a model for signaling events induced by fluid shear stress that incorporates many of the features discussed in this paper (FIG. 4). First, heterotrimeric G-proteins, as well as a small G-proteins, are activated by flow. Indeed, a G protein appears to be required for ERK1/2 activation by flow because ERK1/2 activation is completely inhibited by GDP-beta S. Then, flow activates phospholipase C and generates IP3 and diacylglycerol (DG). IP3 releases Ca2+ from internal Ca2+ stores via IP3 receptor and DG activates PKC. Nollert and colleagues have shown that flow activates PLC and increases IP3. It is possible that several different PKC isozymes are activated by flow including both Ca(2+)-dependent and Ca(2+)-independent isozymes. These different isozymes may have specific downstream substrates. For example, PKC-epsilon may be involved in activation of ERK1/2, while the PKC isozyme responsible for activation of JNK remains unknown. It is also possible that these PKC isozymes may be important in gene transcription events. For example, PKC-zeta has been suggested to be involved in NF-kappa B-mediated gene transcription. Longer term changes in endothelial cell morphology and structure are likely to involve separate kinases. Important candidates for these changes include members of the c-Src and FAK families. c-Src is now considered to be a component of the focal adhesion complex and regulate focal adhesion formation and/or cytoskeletal rearrangement. Recently, stretch, another mechanostress, has been shown to activate c-Src in fetal rat lung cells. It has been clarified that ERK1/2 and JNK are regulated by the small G-proteins, Ras and Rac/Cdc42H, respectively, and their effectors in parallel with each other. Rac and Rho are also thought to be involved in membrane ruffling and/or cytoskeletal rearrangement. Fluid shear stress causes stress fiber formation and focal adhesion rearrangement. Recent study by Malek and Izumo suggested the importance of microtubules in shear stress-induced morphological change and actin stress fiber formation. It is clear that the focal adhesion complex plays an important role in shear stress-induced signal and it is interesting to speculate that shear stress-induced signaling has cross-talk with signaling induced by integrins. As a general model we propose that the integration between the rapid events stimulated by shear stress and the longer term events is mediated by tyrosine kinases that serve to regulate these multiple signal transduction pathways.
...
PMID:Fluid shear stress-mediated signal transduction: how do endothelial cells transduce mechanical force into biological responses? 918 80

B16 melanoma is characterized by high content of GM3 ganglioside, which has been recognized as a melanoma-associated antigen defined by specific monoclonal antibodies. We report now that GM3 is present predominantly (>90%) in the 1% Triton X-100-insoluble, low-density microvesicular fraction ("detergent-insoluble glycosphingolipid-enriched microdomain"; DIGEM) separated on sucrose density-gradient centrifugation. Associated with DIGEM, many signal transducer molecules such as c-Src, FAK, and the low-molecular-weight G-proteins Rho A and H-Ras were also found. Rho A and FAK were found in part, and PLC-beta2 and G alphas were found exclusively, in the high-density fraction. Immunoprecipitation of GM3 present in DIGEM by anti-GM3 antibody DH2, followed by Western blotting, revealed co-precipitation of Rho A and c-Src with GM3. These findings suggest (i) a specific organization of GM3 in close association with Rho A and c-Src within DIGEM at the melanoma cell surface; and (ii) such organizational units may be directly involved in signal transduction, in which glycosphingolipids receive signals which are subsequently transduced by associated transducer molecules.
...
PMID:A close association of GM3 with c-Src and Rho in GM3-enriched microdomains at the B16 melanoma cell surface membrane: a preliminary note. 922 55

The inappropriate activation of protein-tyrosine kinases (PTKs) has been associated with initiation and progression of several types of human cancers. We therefore postulated that immortalization by DNA tumor viruses results in the induction of PTKs fundamental to these processes. An RT-PCR-based screen was thus used to identify PTKs that were abundantly expressed in HPV-18-immortalized epithelial cells and HPV-containing carcinoma cell lines. One of the genes isolated in this screen was the focal adhesion kinase (FAK; pp125FAK), a cytoplasmic protein kinase that is activated in v-src transformed cells or by stimulation with mitogenic polypeptides. FAK also becomes catalytically active upon integrin engagement with extracellular matrix proteins, such as fibronectin. We found that FAK expression and activity were significantly elevated in HPV-18 E6/E7-immortalized human genital epithelial cells relative to their primary cell counterparts. Protein expression and tyrosine phosphorylation of the putative FAK substrate, paxillin, were also notably increased upon HPV-18 immortalization of genital epithelial cells and in HPV-containing cervical carcinoma cell lines. Most significantly, these cells expressed markedly higher levels of both intracellular and extracellular fibronectin, thus providing a mechanism for activation of FAK and increased tyrosine phosphorylation of paxillin. These findings suggest a role for the integrin/FAK-mediated signaling pathway in cervical carcinogenesis and represent one of the first demonstrations of a tyrosine kinase whose activity is elevated following viral immortalization.
...
PMID:Activation of the focal adhesion kinase signal transduction pathway in cervical carcinoma cell lines and human genital epithelial cells immortalized with human papillomavirus type 18. 923 61


<< Previous 1 2 3 4 5 6 7 8 9 10

---