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)

GLP-1, incretin with insulin-independent antidiabetic properties, is insulinomimetic upon glucose metabolism in extrapancreatic tissues, acting through specific receptors not associated to adenylate cyclase activation. We investigated the role of enzymes mediating insulin actions, in the GLP-1-induced glycogen synthase a activation in rat hepatocytes. GLP-1, like insulin, activates PI3K/PKB, p70s6k, p44 and p42 MAP-kinase. Wortmannin (PI3K/PKB inhibitor) blocked the stimulatory action of insulin on glycogen synthase a and reduced that of GLP-1; rapamycin (p70s6k inhibitor) was ineffective and PD98059 (MEK/MAPK inhibitor) decreased only the insulin effect; okadaic acid (PP-2A inhibitor) was ineffective, while TNFalpha (PP-1 inhibitor) blocked the action of insulin and reduced that of GLP-1; H-7 or Ro 31-8220 (PKC inhibitors) decreased the GLP-1 effect, while only H-7 reduced that of insulin. The activation of PI3K/PKB, PKC and PP-1, but not PP-2A, seems to mediate the GLP-1 stimulatory action on glycogen synthase a in rat hepatocytes, while MAPKs and p70s6k could participate in other GLP-1 effects.
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PMID:Cell signalling of the GLP-1 action in rat liver. 1285 Feb 80

Extensive data indicate that the transcription factor NF kappa B is activated by signals downstream of oncoproteins such as Ras or breakpoint cluster region (BCR)-ABL. Consistent with this, evidence has been presented that NF kappa B activity is required for Ras and BCR-ABL to transform cells. However, it remains unclear whether these oncoproteins activate a full spectrum of NF kappa B-dependent gene expression or whether they may augment or interfere with other stimuli that activate NF kappa B. The data presented here indicate that BCR-ABL expression in 32D myeloid cells or oncogenic Ras expression in murine fibroblasts blocks the ability of tumor necrosis factor (TNF) to activate NF kappa B. This suppression of NF kappa B is manifested by an inhibition of TNF-induced inhibitor of NF kappa B (IKK) activity and NF kappa B DNA binding potential but not by blocking TNF-induced nuclear accumulation of NF kappa B/p65. The inhibition of NF kappa B is not observed in oncogenic Raf-expressing cells and is not fully restored by the suppression of PI3-kinase or MEK pathways. Oncogenic Ras suppresses the ability of TNF to activate the expression of NF kappa B-dependent genes, such as iNOS (inducible nitric oxide synthase) and RANTES (regulated on activation normal T-cell expressed and secreted). These studies suggest that the ability of Ras and BCR-ABL to activate NF kappa B involves an uncharacterized pathway that does not involve classic IKK activity and that suppresses the TNF-induced IKK pathway through a Raf/MEK/Erk-independent mechanism.
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PMID:Oncoprotein suppression of tumor necrosis factor-induced NF kappa B activation is independent of Raf-controlled pathways. 1285 13

Activation of the Ras-MAPK signal transduction pathway is necessary for biological responses both to growth factors and ECM. Here, we provide evidence that phosphorylation of S298 of MAPK kinase 1 (MEK1) by p21-activated kinase (PAK) is a site of convergence for integrin and growth factor signaling. We find that adhesion to fibronectin induces PAK1-dependent phosphorylation of MEK1 on S298 and that this phosphorylation is necessary for efficient activation of MEK1 and subsequent MAPK activation. The rapid and efficient activation of MEK and phosphorylation on S298 induced by cell adhesion to fibronectin is influenced by FAK and Src signaling and is paralleled by localization of phospho-S298 MEK1 and phospho-MAPK staining in peripheral membrane-proximal adhesion structures. We propose that FAK/Src-dependent, PAK1-mediated phosphorylation of MEK1 on S298 is central to the organization and localization of active Raf-MEK1-MAPK signaling complexes, and that formation of such complexes contributes to the adhesion dependence of growth factor signaling to MAPK.
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PMID:PAK1 phosphorylation of MEK1 regulates fibronectin-stimulated MAPK activation. 1287 77

Cell migration on extracellular matrix requires the turnover of integrin-dependent adhesions. The nonreceptor tyrosine kinases Src and FAK regulate focal-adhesion turnover by poorly understood mechanisms. ERK/MAP kinase-mediated activation of the protease Calpain 2 also promotes focal-adhesion turnover; however, it is not known if this is linked to the activities of Src and FAK. Calpain 2 has previously been demonstrated to colocalize with focal-adhesion structures and can cleave several focal-adhesion complex components, including FAK. Studies utilizing Calpain inhibitors or Calpain-deficient cells confirm that Calpain's role in regulating focal-adhesion turnover is necessary for cell migration. We have identified a novel and kinase-independent function for FAK as an adaptor molecule that mediates the assembly of a complex consisting of at least Calpain 2 and p42ERK. Mutation of proline residues (Pro2) in the amino-terminal region of FAK blocks direct binding with Calpain 2 and also prevents formation of the Calpain 2/p42ERK complex in cells. We show that both complex formation and MEK/ERK activity are associated with Calpain-mediated proteolysis of FAK and focal adhesion turnover during transformation and migration. Furthermore, FAK is necessary for recruiting both Calpain 2 and p42ERK/MAPK to peripheral adhesion sites facilitating maximal Calpain activity.
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PMID:A novel role for FAK as a protease-targeting adaptor protein: regulation by p42 ERK and Src. 1293 30

We have reported previously that reactivation of progesterone receptor (PR) expression in estrogen receptor (ER)- and PR-negative MDA-MB-231 breast cancer cells enabled progesterone to inhibit cell growth and invasiveness, and to induce remarkable focal adhesions. The present study addressed molecular mechanisms that mediate these anticancer effects of progesterone in the PR-transfected breast cancer cells ABC28. In response to progesterone treatment are the marked up-regulation of cyclin-dependent kinase inhibitor protein p21WAF1/CIP1 and decreased expression of cyclin A, cyclin B1, and cyclin D1 that are required for G1 progression and during cell mitosis. Progesterone also induced down-regulation of phosphorylated MAPK (p42/44 MAPK). Furthermore, this study also demonstrated that MEK inhibitor PD98059 that inhibits the phosphorylation of p42/44 MAPK also caused reduction of cyclin D1 level and inhibition of cell proliferation. These results suggest that inhibition of p42/44 MAPK pathway is part of the mechanisms mediating progesterone's growth-inhibitory effect. On the other hand, progesterone-induced focal adhesion is mediated by separate pathway. Whereas PD98059 exhibited no effects on cell adhesion, inhibitory antibody to beta1-integrin was able to reverse progesterone-induced focal adhesion and progesterone-induced increase in the phosphorylation of focal adhesion kinase. On the other hand, beta1-integrin antibody had no effect on progesterone-mediated growth inhibition and on progesterone-mediated expression of cyclins p21CIP1/WAF1 and phosphorylation of P42/P44 MAPK. In the context of complex functions of progesterone in breast cancer and reproductive organs, identification of distinct pathways offers new strategies for designing therapeutic agents to target the specific pathway so as to minimize the side effects.
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PMID:Distinct molecular pathways mediate progesterone-induced growth inhibition and focal adhesion. 1297 Jan 68

The FMR2 gene is dysregulated by the fragile X E triplet repeat expansion in patients with FRAXE mental retardation syndrome. A CCG triplet, located in the 5' untranslated region of the FRAXE gene undergoes expansion and methylation in these patients, eliminating detectable gene transcription. FRAXE syndrome is distinct from fragile X syndrome, a more common genetic form of mental retardation caused by expansion and methylation of a similar repeat in the FMR1 gene located 600 kb proximal to FRAXE. FRAXE syndrome is rare, and patients' phenotypes are highly variable, leading to difficulties with predicting specific FMR2 functions based on the human disease. Recently, Lilliputian(Lilli), a Drosophila FMR2 orthologue, was identified; this gene has been linked with several signal transduction pathways, including the transforming growth factor-beta (TGF-beta) pathway, the Raf/MEK/MAP kinase (MAPK) pathway, and the P13K/PKB pathway. Mutation of Lilli shows defects in germinal band extension, cytoskeletal structure, cell growth, and organ development. The Lilli gene suggests possible functions for FMR2 (and related genes) in humans and mice, but cannot predict specific functions. Modeling FMR2 mutation in the mouse will be useful to understand specific functions of this gene in vertebrates. This review presents what has been learned thus far from the FMR2 knockout mouse model and suggests future studies on this model in order to compare it with the human FRAXE mental retardation disorder, Lilli mutants in Drosophila and other mouse models of genes in this family.
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PMID:FMR2 function: insight from a mouse knockout model. 1452 73

In this study, we examined the cellular and molecular responses of fibroblasts cultured on a polyelectrolyte complex (PEC) derived from sulfated chitin as a polyanion and chitosan as a polycation. On PEC-coated dishes, the fibroblasts aggregated and then developed spheroid-like structures. At earlier stages of culture, DNA synthesis of cells cultured on PEC was stimulated approximately 75% higher than control cells. Among various signaling molecules examined, including mitogen-activated protein kinases, Akt/PKB and p53, an extracellular-signal-regulated kinase (ERK) was selectively and constitutively phosphorylated in cells cultured on PEC. The constitutive phosphorylation of ERK was derived from an activation of the ERK kinase MEK, but not from an inactivation of the ERK phosphatase MKP-1. Furthermore, ERK phosphorylation was almost abolished by a membrane receptor tyrosine kinase inhibitor. The enhanced phosphorylation of focal adhesion kinase, a downstream molecule of integrins, was also observed in cells cultured on PEC. These results suggest that fibroblasts recognize PEC as a continuous mitogenic stimulant which results in the constitutive activation of the MEK-ERK pathway toward mitogenesis. Further, PEC interacts with the cell membrane leading to activation of membrane molecules, including integrins and receptor tyrosine kinases. These responses may account, at least in part, for the potential use of PEC as a biomaterial for tissue regeneration.
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PMID:Enhanced DNA synthesis accompanied by constitutive phosphorylation of the ERK pathway in human fibroblasts cultured on a polyelectrolyte complex. 1453 74

The hematopoietic-specific Galpha16 protein has recently been shown to mediate receptor-induced activation of the signal transducer and activator of transcription 3 (STAT3). In the present study, we have delineated the mechanism by which Galpha16 stimulates STAT3 in human embryonic kidney 293 cells. A constitutively active Galpha16 mutant, Galpha16QL, stimulated STAT3-dependent luciferase activity as well as the phosphorylation of STAT3 at both Tyr705 and Ser727. Galpha16QL-induced STAT3 activation was enhanced by overexpression of extracellular signal-regulated kinase 1 (ERK1), but was inhibited by U0126, a Raf-1 inhibitor, and coexpression of the dominant negative mutants of Ras and Rac1. Inhibition of phospholipase Cbeta, protein kinase C, and calmodulin-dependent kinase II by their respective inhibitors also suppressed Galpha16QL-induced STAT3 activation. The involvement of tyrosine kinases such as c-Src and Janus kinase 2 and 3 (JAK2 and JAK3) in Galpha16QL-induced activation of STAT3 was illustrated by the combined use of selective inhibitors and dominant negative mutants. In contrast, c-Jun N-terminal kinase, p38 MAPK, RhoA, Cdc42, phosphatidylinositol 3-kinase, and the epidermal growth factor receptor did not appear to be required. Similar observations were obtained with human erythroleukemia cells, where STAT3 phosphorylation was stimulated by C5a in a PTX-insensitive manner. Collectively, these results highlight the important regulatory roles of the Ras/Raf/MEK/ERK and c-Src/JAK pathways on the stimulation of STAT3 by activated Galpha16. Demonstration of the involvement of different kinases in Galpha16QL-induced STAT3 activation supports the involvement of multiple signaling pathways in the regulation of transcription by G proteins.
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PMID:Constitutively active Galpha16 stimulates STAT3 via a c-Src/JAK- and ERK-dependent mechanism. 1455 Dec 13

Glomerular epithelial cell (GEC) injury and apoptosis may contribute to sclerosis in glomerulonephritis. The present study addresses signals that regulate survival of GEC in culture and in the acute puromycin aminonucleoside nephrosis (PAN) model of GEC injury in vivo. Compared with GEC on plastic substratum, adhesion to collagen increased activation of focal adhesion kinase (FAK), c-Src, and ERK and facilitated survival (prevented apoptosis). GEC on plastic exhibited increased caspase-8 and -9 activities, increased expression of the proapoptotic protein, Bax, and decreased the antiapoptotic protein, Bcl-XL, compared with collagen. Stable expression of constitutively active mutants of FAK (CD2-FAK) or MEK (R4F-MEK) activated the ERK pathway and supplanted the requirement of collagen for survival. In contrast, expression of a Ras mutant that activates phosphatidylinositol 3-kinase but blocks ERK activation or pharmacological inhibition of the ERK pathway decreased survival on collagen. Glomeruli isolated from rats with PAN revealed increased beta1-integrin expression, along with increased activation of FAK, c-Src, and ERK, compared with controls. EGF receptor activation was undetectable in PAN. Therefore, adhesion to collagen, resulting in activation of FAK and the Ras-ERK pathway, supports GEC survival. Analogous signals for GEC survival are activated in PAN.
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PMID:Extracellular matrix regulates glomerular epithelial cell survival and proliferation. 1455 18

Recently we demonstrated that lipopolysaccharide (LPS) promotes activation of the Ras/ERK cascade in medfly hemocytes and that phagocytosis of Escherichia coli by insect hemocytes is mediated by an integrin-dependent process via the activation of FAK/Src complex (J Biol Chem 273 (1998) 14813; FEBS Letters 496 (2001) 55). In the current study we wanted to further elucidate the effects of LPS on medfly hemocytes, in order to better understand the regulation of the evolutionary conserved signaling mechanisms between insects and mammals. We initially observed that different stimuli, including LPS, E. coli, RGD, fibronectin and heat shock activate hemocyte ERK. The response of hemocytes to these stimuli denoted that hemocyte ERK is evidently stimulated by at least an LPS receptor and via an integrin-mediated process. The medfly hemocytes respond to LPS by changing their morphology, inducing the activation of several signaling pathways, including Ras/MEK/ERK, PI-3K/ERK and Rho pathways and contributing to LPS uptake. Experiments based on inhibitors of specific signaling pathways, such as manumycin A, toxin A, U0126, PD98059 and wortmannin revealed that Ras, MEK and PI-3K are involved in the activation of ERK. Whether PI-3K is an intermediate of Ras/MEK/ERK pathway or activates ERK via other signaling pathway it remains to be elucidated. ERK is not activated via Rho pathway, denoting that Rho may not be an upstream effector molecule of ERK pathway. Regarding the role(s) that these kinases play in hemocytes, it can be suggested that PI-3K and Rho GTPases can modulate hemocyte shape changes, whereas ERK, Ras and MEK cannot. In addition, PI-3K as well as Ras and MEK through ERK activation participate in LPS endocytosis. Therefore, PI-3K shares a dual role; it is involved both in cell shape changes and in LPS endocytosis. Since ERK activation appears to be independent of the integrity of actin filaments, as cytochalasin D and latrunculin A did not block ERK activation, it can be concluded that LPS endocytosis is independent of actin cytoskeleton remodeling as is the case in mammalian systems.
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PMID:Distinct LPS-induced signals regulate LPS uptake and morphological changes in medfly hemocytes. 1456 59


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