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)

Paxillin is a focal adhesion adapter protein involved in integrin signaling. Paxillin LD motifs bind several focal adhesion proteins including the focal adhesion kinase, vinculin, the Arf-GTPase-activating protein paxillin-kinase linker, and the newly identified actin-binding protein actopaxin. Microsequencing of peptides derived from a 50-kDa paxillin LD1 motif-binding protein revealed 100% identity with integrin-linked kinase (ILK)-1, a serine/threonine kinase that has been implicated in integrin, growth factor, and Wnt signaling pathways. Cloning of ILK from rat smooth muscle cells generated a cDNA that exhibited 99.6% identity at the amino acid level with human ILK-1. A monoclonal antibody raised against a region of the carboxyl terminus of ILK, which is identical in rat and human ILK-1 protein, recognized a 50-kDa protein in all cultured cells and tissues examined. Binding experiments showed that ILK binds directly to the paxillin LD1 motif in vitro. Co-immunoprecipitation from fibroblasts confirmed that the association between paxillin and ILK occurs in vivo in both adherent cells and cells in suspension. Immunofluorescence microscopy of fibroblasts demonstrated that endogenous ILK as well as transfected green fluorescent protein-ILK co-localizes with paxillin in focal adhesions. Analysis of the deduced amino acid sequence of ILK identified a paxillin-binding subdomain in the carboxyl terminus of ILK. In contrast to wild-type ILK, paxillin-binding subdomain mutants of ILK were unable to bind to the paxillin LD1 motif in vitro and failed to localize to focal adhesions. Thus, paxillin binding is necessary for efficient focal adhesion targeting of ILK and may therefore impact the role of ILK in integrin-mediated signal transduction events.
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PMID:Integrin-linked kinase (ILK) binding to paxillin LD1 motif regulates ILK localization to focal adhesions. 1130 46

The L-type calcium channel is the major calcium influx pathway in vascular smooth muscle and is regulated by integrin ligands, suggesting an important link between extracellular matrix and vascular tone regulation in tissue injury and remodeling. We examined the role of integrin-linked tyrosine kinases and focal adhesion proteins in regulation of L-type calcium current in single vascular myocytes. Soluble tyrosine kinase inhibitors blocked the increase in current produced by alpha(5) integrin antibody or fibronectin, whereas tyrosine phosphatase inhibition enhanced the effect. Cell dialysis with an antibody to focal adhesion kinase or with FRNK, the C-terminal noncatalytic domain of focal adhesion kinase, produced moderate (24 or 18%, respectively) inhibition of basal current but much greater inhibition (63 or 68%, respectively) of integrin-enhanced current. A c-Src antibody and peptide inhibitors of the Src homology-2 domain or a putative Src tyrosine phosphorylation site on the channel produced similar inhibition. Antibodies to the cytoskeletal proteins paxillin and vinculin, but not alpha-actinin, inhibited integrin-dependent current by 65-80%. Therefore, alpha(5)beta(1) integrin appears to regulate a tyrosine phosphorylation cascade involving Src and various focal adhesion proteins that control the function of the L-type calcium channel. This interaction may represent a novel mechanism for control of calcium influx in vascular smooth muscle and other cell types.
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PMID:Regulation of the L-type calcium channel by alpha 5beta 1 integrin requires signaling between focal adhesion proteins. 1138 63

This study was directed at the expression of focal adhesion kinase (pp125FAK) which is located together with vinculin and talin in the spot of cellular adhesion. The authors' intention was to collect reliable data on this important kinase in the signal pathways so as to provide in-depth materials for exploring the mechanism of tumor metastasis to lymphatic vessels. The immunohistochemical method was used to study the expression of FAK in lymphatic endothelial cells of metastaltci adenocarcinoma of rectum and its adjacent lymph-nodes. The result demonstrated that lymphatic endothelial cells expressed pp125FAK when lymphatic vessels were invaded by cancer cells. Reaction production was located in the cytoplasm. This study provides that there was a strong correlation between the expression of FAK in lymphatic endothelial cells and the metastasis of cancer to lymphatic vessels.
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PMID:[Expression of focal adhesion kinase in lymphatic endothelial cells of metastasis]. 1138 47

Recent studies have shown that integrin alpha v beta 3, a receptor for vitronectin, plays an important role in tumor-induced angiogenesis and tumor growth and that antagonists of alpha v beta 3 inhibit angiogenic processes including endothelial cell adhesion and migration. On the other hand, most inhibitors of integrin alpha v beta 3 are peptide antagonists that include the Arg-Gly-Asp (RGD) motif. We therefore reasoned that non-peptide inhibitors of endothelial cell adhesion to vitronectin might be useful for inhibition of tumor angiogenesis in vivo. We screened for low-molecular-weight natural products able to inhibit adhesion of human umbilical vein endothelial cells (HUVECs) to vitronectin, and pyrrothine group compounds including aureothricin, thioaurin and thiolutin were isolated from microbial culture broths. Of these compounds, thiolutin inhibited adhesion of HUVECs to vitronectin the most effectively (IC(50), 0.83 microM). In vivo experiments showed that thiolutin significantly suppressed angiogenesis induced by tumor cells (S-180), a pathological form of neovascularization, in a mouse dorsal air sac assay system. To explore the mechanism of inhibition of HUVEC adhesion to vitronectin by thiolutin, we examined the effect of this agent on intracellular cell adhesion signaling. We found that the amount of paxillin in HUVECs was significantly reduced by thiolutin treatment, while those of other focal adhesion proteins including vinculin and focal adhesion kinase (FAK) were not. Metabolic labeling experiments showed that thiolutin enhanced degradation of paxillin in HUVECs. Protease inhibitors (MG115 and E64-D) decreased the rate of degradation of the paxillin induced by thiolutin and partially restored thiolutin-induced inhibition of HUVEC adhesion to vitronectin. Based on these findings, we concluded that thiolutin, an inhibitor of HUVEC adhesion to vitronectin, reduces the paxillin level in HUVECs and suppresses tumor cell-induced angiogenesis in vivo.
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PMID:Thiolutin, an inhibitor of HUVEC adhesion to vitronectin, reduces paxillin in HUVECs and suppresses tumor cell-induced angiogenesis. 1143 93

The small GTPases of the Rho family are intimately involved in integrin-mediated changes in the actin cytoskeleton that accompany cell spreading and motility. The exact means by which the Rho family members elicit these changes is unclear. Here, we demonstrate that the interaction of paxillin via its LD4 motif with the putative ARF-GAP paxillin kinase linker (PKL) (Turner et al., 1999), is critically involved in the regulation of Rac-dependent changes in the actin cytoskeleton that accompany cell spreading and motility. Overexpression of a paxillin LD4 deletion mutant (paxillinDeltaLD4) in CHO.K1 fibroblasts caused the generation of multiple broad lamellipodia. These morphological changes were accompanied by an increase in cell protrusiveness and random motility, which correlated with prolonged activation of Rac. In contrast, directional motility was inhibited. These alterations in morphology and motility were dependent on a paxillin-PKL interaction. In cells overexpressing paxillinDeltaLD4 mutants, PKL localization to focal contacts was disrupted, whereas that of focal adhesion kinase (FAK) and vinculin was not. In addition, FAK activity during spreading was not compromised by deletion of the paxillin LD4 motif. Furthermore, overexpression of PKL mutants lacking the paxillin-binding site (PKLDeltaPBS2) induced phenotypic changes reminiscent of paxillinDeltaLD4 mutant cells. These data suggest that the paxillin association with PKL is essential for normal integrin-mediated cell spreading, and locomotion and that this interaction is necessary for the regulation of Rac activity during these events.
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PMID:The LD4 motif of paxillin regulates cell spreading and motility through an interaction with paxillin kinase linker (PKL). 1144 98

Interaction between implant materials and bone cells contributes to the clinical success of dental implants. The object of this study was to investigate the initial attachment and subsequent behavior of human osteoblastic cells (Saos-2) to pure titanium (Ti), hydroxyapatite (HA), and glass. We, therefore, performed a time-course study for examining the area, attachment rate, distribution of focal adhesion kinase (FAK) vinculin, and actin, and the motility of Saos-2 cells on the materials. On Ti, cell area increased gradually, whereas on HA, cells spread quickly, but quitted spreading at 12 h after cell seeding. The number of cells on HA was greater than on the other materials. On Ti, the numbers of FAK- and vinculin-positive focal adhesions increased continuously. On HA, although the number of FAK-positive focal adhesions also increased continuously, the number of vinculin-positive focal adhesions decreased. Furthermore, actin staining showed that the cells on HA poorly formed stress fibers with weak polarity, whereas the cell on Ti possessed well-defined polarized stress fibers. On HA, cells started extension earlier than on Ti, motility was inactive, and the cells settled on the materials. These results suggest that the earlier settling of osteoblasts on HA might result in earlier osteogenesis on HA than other materials.
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PMID:Substrate affects the initial attachment and subsequent behavior of human osteoblastic cells (Saos-2). 1145 66

Activation of tyrosine kinases during integrin-mediated cell-matrix adhesion is involved both in the regulation of focal contact assembly and in the initiation of signaling processes at the cell-matrix adhesive interface. In order to determine the role of pp60(c-src) and related kinases in these processes, we have compared the dynamic reorganization of phosphotyrosine, vinculin, focal adhesion kinase and tensin in cells with altered expression of Src-family kinases. Both null cells for pp60(c-src) and triple knockout cells for pp60(c-src), pp59(fyn), and pp62(c-yes) exhibited decreased phosphotyrosine levels in focal contacts when compared with wild-type cells. pp60(c-src)-null cells also exhibited faster assembly of cell-matrix adhesions and a more exuberant recruitment of FAK to these sites. Tensin, which normally segregates into fibrillar adhesions was localized in large focal contacts in the two mutant cell lines, suggesting involvement of pp60(c-src) in the segregation of focal contacts and fibrillar adhesions. Moreover, treatment of wild-type cells with tyrphostin AG1007, which inhibits both pp60(c-src) and FAK activity, induced accumulation of tensin in peripheral focal adhesions. These findings demonstrate that Src family kinases, and pp60(c-src) in particular, have a central role in regulating protein dynamics at cell-matrix interfaces, both during early stages of interaction and in mature focal contacts.
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PMID:pp60(c-src) and related tyrosine kinases: a role in the assembly and reorganization of matrix adhesions. 1149 67

Increased pericellular proteolysis due to an imbalance between MMPs (matrix metalloproteinases) and TIMPs (tissue inhibitors of metalloproteinases) promotes early stages of tumorigenesis. We have reported that TIMP-1 down-regulation confers tumorigenicity on immortal Swiss 3T3 fibroblasts. In pursuit of the mechanism involved in this transformation, we asked whether MMP inhibitors modulate contact inhibition and cell adhesion, because the dysregulation of these events is essential for cellular transformation. Using both genetic and biochemical means, we demonstrate that MMP inhibitors regulate fibroblast cell adhesion. TIMP-1 down-regulated cells formed dense, multilayered colonies, suggesting a loss of contact inhibition. Recombinant TIMP-1 and synthetic MMP inhibitors (MMPi) restored normal cell contact and density of these cells in a dose-dependent manner. Consequently, the effect of MMPi on both cell-extracellular matrix (ECM) and cell-cell adhesion were investigated. Upon MMPi treatment, p125(FAK) was redistributed, together with vinculin, to points of cell-ECM contact. Furthermore, phosphorylation of p125(FAK) was restored to levels similar to that of wild type. In parallel, MMPi treatment increased cadherin levels and stabilized cadherin-mediated cell-cell contacts. Moreover, enhanced cadherin function was evident as increased calcium-dependent cell-cell aggregation and co-localization of cadherin and beta-catenin at the cell membrane. We also obtained independent evidence of altered cadherin function using timp-1(-/-) mouse embryonic fibroblasts. Our data provide provocative evidence that increased pericellular proteolysis impacts cell adhesion systems to offset normal contact inhibition, with subsequent effects on cell transformation and tumorigenesis.
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PMID:MMP inhibitors augment fibroblast adhesion through stabilization of focal adhesion contacts and up-regulation of cadherin function. 1150 Apr 88

Group A streptococcus (GAS) induces its own entry into eukaryotic cells in vitro and in vivo. Fibronectin (Fn) bound to protein F1, a GAS surface protein, acts as a bridge connecting the bacterium to host cell integrins. This triggers clustering of integrins, which acquire a polar pattern of distribution similar to that of protein F1 on the GAS surface. A unique and transient adhesion complex is formed at the site of GAS entry, which does not contain alpha-actinin. Vinculin is recruited to the site of GAS entry but is not required for uptake. The invading GAS recruits focal adhesion kinase (FAK), which is required for uptake and is tyrosine phosphorylated. The Src kinases, Src, Yes and Fyn, enhance the efficiency of GAS uptake but are not absolutely required for GAS entry. In addition, Rac and Cdc42, but not Rho, are required for the entry process. We suggest a model in which integrin engagement by Fn-occupied protein F1 triggers two independent signalling pathways. One is initiated by FAK recruitment and tyrosine phosphorylation, whereas the other is initiated by the recruitment and activation of Rac. The two pathways subsequently converge to trigger actin rearrangement leading to bacterial uptake.
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PMID:De novo formation of focal complex-like structures in host cells by invading Streptococci. 1153 25

ACK2 (activated Cdc42-associated tyrosine kinase-2) is a nonreceptor tyrosine kinase that is a specific target/effector for the GTP-binding protein Cdc42. Thus far the biological function of this tyrosine kinase has not been determined. Using an inducible eukaryotic expression system in fibroblasts, we demonstrate that ACK2 can strongly influence cell shape and growth as well as focal complex formation. ACK2 was found to associate with the focal adhesion complex components talin and vinculin, but not with the focal adhesion kinase (FAK), in a kinase-independent manner. The tyrosine kinase activity of FAK was also inhibited in cells overexpressing both wild-type and kinase-defective ACK2. This may be due to a competition between ACK2 and FAK for Src, which is an essential cofactor for FAK activation, as we have found that ACK2 specifically binds Src in cells. The ACK2-Src interaction appears to be mediated by the SH3 domain of Src, and the phosphorylation of ACK2 is enhanced in cells overexpressing the hyperactivated Src(Y527F) mutant. Overexpression of both wild-type and kinase-defective ACK2 also results in a severe inhibition of cell growth. In addition, ACK2 dissolves actin stress fibers and disassembles focal complexes but in a kinase-dependent manner. These results, taken together with previous studies demonstrating an association of ACK2 with integrin beta(1) (Yang, W., Lin, Q., Guan, J.-L., Cerione, R. A. (1999) J. Biol. Chem. 274, 8524-8530) and clathrin (Yang, W., Lo, C. G., Dispenza, T., and Cerione, R. A. (2001) J. Biol. Chem. 276, 17468-17473), suggest that the binding and protein tyrosine kinase activities of ACK2 coordinate changes in cell morphology and growth with the disassembly of focal adhesion sites, perhaps to organize new integrin complexes that are required for endocytosis and/or for cellular differentiation.
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PMID:The nonreceptor tyrosine kinase ACK2, a specific target for Cdc42 and a negative regulator of cell growth and focal adhesion complexes. 1153 92


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