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)

We have previously shown that the IL-6R in a growth-responsive B cell line, AF10, induces activation of mitogen-activated protein (MAP) kinase. Here we demonstrate the activation of Raf-1 and MEK-1, which act as a MAP kinase kinase kinase and a MAP kinase kinase, respectively, in the MAP kinase cascade induced by IL-6 in AF10 cells. IL-6 also induced tyrosine phosphorylation of the signaling transducing subunit of the IL-6R in AF10 cells, along with tyrosine phosphorylation of the gp130-associated tyrosine protein kinase JAK1 and the adaptor molecule p52shc. Although induction of tyrosine phosphorylation and activation of MAP kinase by IL-6 in a differentiation-responsive B cell line, SKW 6.4, were below the limits of detection, the phorbol ester PMA did activate Raf-1, MEK-1, and MAP kinase without inducing the phosphorylation of gp130, JAKs, or p52shc. These results suggest that JAK kinase family members associated with the IL-6R may participate in the activation of MAP kinase in AF10 cells by way of an adaptor protein and Ras-dependent kinase cascade.
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PMID:Involvement of Janus kinases, p52shc, Raf-1, and MEK-1 in the IL-6-induced mitogen-activated protein kinase cascade of a growth-responsive B cell line. 796 20

The loss of integrin-mediated cell-matrix contact induces apoptosis ('anoikis') in certain cell types. Recently it has been shown that protein kinase signaling pathways control anoikis both positively and negatively. Focal adhesion kinase, when activated by integrins, can suppress anoikis. Phosphatidylinositol 3-kinase and the AKT oncoprotein may mediate the anoikis-suppressing effects of focal adhesion kinase. Conversely, the stress-activated protein kinase/Jun amino-terminal kinase pathway promotes anoikis. Latest results indicate that caspase-mediated cleavage of the first component of this latter pathway, MEKK-1, may trigger activation of this pathway in anoikis. In addition, certain integrins may regulate bcl-2 expression levels, possibly adjusting the threshold for anoikis.
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PMID:Integrins and anoikis. 933 Aug 74

Caspases are activated during apoptosis and cleave specific proteins, resulting in the irreversible commitment to cell death. The signal transduction proteins MEKK1, p21-activated kinase 2, and focal adhesion kinase are caspase substrates that contribute to the cell death response when cleaved. Thirty additional signaling proteins were screened for their ability to be cleaved during apoptosis. Twenty-two of these proteins were not affected in Jurkat cells stimulated to undergo apoptosis by Fas ligation, exposure to ultraviolet-C or incubation with etoposide. Ras GTPase-activating protein was found to be a caspase substrate whose cleavage followed the same time course as that for activation of caspase activity and the cleavage of MEKK1 and focal adhesion kinase. Four additional proteins, Cbl, Cbl-b, Raf-1, and Akt-1, were cleaved later in the apoptotic response. These signaling proteins were similarly cleaved in U937 cells undergoing apoptosis. Cleavage of the proteins was blocked by caspase inhibitors in Jurkat cells or in U937 cells expressing BclxL, demonstrating that the cleavage was dependent on caspase activation. Cleavage of Raf-1 and Akt correlated with the loss of extracellular signal-regulated kinase and Akt activities in apoptotic cells. Neither c-Jun N-terminal kinase nor p38 mitogen-activated protein kinase was cleaved in cells undergoing apoptosis, and the activation of the c-Jun N-terminal kinase and p38 mitogen-activated protein kinase pathways was not compromised in apoptotic cells. These results indicate that caspase-dependent cleavage of specific proteins induces the turn off of survival pathways, such as the extracellular signal-regulated kinase and phosphatidylinositol-3 kinase/Akt pathways, that could otherwise interfere with the apoptotic response.
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PMID:Caspase-dependent cleavage of signaling proteins during apoptosis. A turn-off mechanism for anti-apoptotic signals. 950 28

Stimulation of the high affinity IgE receptor (FC epsilonRI) as well as a variety of stresses induce activation of c-Jun N-terminal protein kinases (JNKs) stress-activated protein kinases in mast cells. At least three distinct signaling pathways leading to JNK activation have been delineated based on the involvements of Bruton's tyrosine kinase (Btk), protein kinase C (PKC), and the JNK-activating cascades composed of multiple protein kinases. The PKC-dependent pathway, which is inhibited by a PKC inhibitor Ro31-8425 and can be activated by PMA, functions as a major route in FC epsilon RI-stimulated mast cells derived from btk gene knockout mice. On the other hand, wild-type mouse-derived mast cells use both PKC-dependent and PKC-independent pathways for JNK activation. A PKC-independent pathway is regulated by Btk and SEK1 via the PAK-->MEKK1-->SEK1-->JNK cascade, and is sensitive to phosphatidylinositol 3-kinase inhibitors, wortmannin and LY-294002, while the PKC-dependent pathway is affected to a lesser extent by both wortmannin treatment and overexpression of wild-type and dominant negative mutant SEK1 proteins. Another PKC-independent pathway involves Btk and MKK7, a recently cloned direct activator of JNK. Among the stresses tested, UV irradiation seems to activate Btk and JNK via the PKC-independent pathways.
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PMID:Multiple signaling pathways for the activation of JNK in mast cells: involvement of Bruton's tyrosine kinase, protein kinase C, and JNK kinases, SEK1 and MKK7. 971 46

MEKK2 and MEKK3 are two closely related mitogen-activated protein kinase (MAPK) kinase kinases. The kinase domains of MEKK2 and MEKK3 are nearly identical, although their N-terminal regulatory domains are significantly divergent. By yeast two-hybrid library screening, we have identified MEK5, the MAPK kinase in the big mitogen-activated protein kinase 1 (BMK1)/ERK5 pathway, as a binding partner for MEKK2. MEKK2 expression stimulates BMK1/ERK5 activity, the downstream substrate for MEK5. Compared with MEKK3, MEKK2 activated BMK1/ERK5 to a greater extent, which might correlate with a higher affinity MEKK2-MEK5 interaction. A dominant negative form of MEK5 blocked the activation of BMK1/ERK5 by MEKK2, whereas activation of c-Jun N-terminal kinase (JNK) was unaffected, showing that MEK5 is a specific downstream effector of MEKK2 in the BMK1/ERK5 pathway. Activation of BMK1/ERK5 by epidermal growth factor and H2O2 in Cos7 and HEK293 cells was completely blocked by a kinase-inactive MEKK3 (MEKK3kin(-)), whereas MEKK2kin(-) had no effect. However, in D10 T cells, expression of MEKK2kin(-) but not MEKK3kin(-) inhibited BMK1/ERK5 activity. Two-hybrid screening also identified Lck-associated adapter/Rlk- and Itk-binding protein (Lad/RIBP), a T cell adapter protein, as a binding partner for MEKK2. MEKK2 and Lad/RIBP colocalize at the T cell contact site with antigen-loaded presenting cells, demonstrating cotranslocation of MEKK2 and Lad/RIBP during T cell activation. MEKK3 neither binds Lad/RIBP nor is recruited to the T cell contact with antigen presenting cell. MEKK2 and MEKK3 are differentially associated with signaling from specific upstream receptor systems, whereas both activate the MEK5-BMK1/ERK5 pathway.
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PMID:MEKK2 associates with the adapter protein Lad/RIBP and regulates the MEK5-BMK1/ERK5 pathway. 1107 40

The mechanisms by which interferon-alpha (IFN-alpha) mediates its anti-leukemic effects in chronic myelogenous leukemia (CML) cells are not known. We determined whether p38 MAPK is activated by IFN-alpha in BCR-ABL-expressing cells and whether its function is required for the generation of growth inhibitory responses. IFN-alpha treatment induced phosphorylation/activation of p38 in the IFN-alpha-sensitive KT-1 cell line, but not in IFN-alpha-resistant K562 cells. Consistent with this, IFN-alpha treatment of KT-1 (but not K562) cells induced activation of the small GTPase Rac1, which functions as an upstream regulator of p38. In addition, IFN-alpha-dependent phosphorylation/activation of p38 was induced by treatment of primary granulocytes isolated from the peripheral blood of patients with CML. To define the functional role of the Rac1/p38 MAPK pathway in IFN-alpha signaling, the effects of pharmacological inhibition of p38 on the induction of IFN-alpha responses were determined. Treatment of KT-1 cells with the p38-specific inhibitors SB203580 and SB202190 reversed the growth inhibitory effects of IFN-alpha. On the other hand, the MEK kinase inhibitor PD098059 had no effects, further demonstrating the specificity of these findings. To directly determine the significance of IFN-alpha-dependent activation of p38 in the induction of the anti-leukemic effects of IFN-alpha, we evaluated the effects of p38 inhibition on leukemic colony formation in bone marrow samples of patients with CML. IFN-alpha inhibited leukemic granulocyte/macrophage colony formation in a dose-dependent manner, whereas concomitant treatment with p38 inhibitors reversed such an inhibition. Thus, the Rac1/p38 MAPK pathway is activated by IFN-alpha in BCR-ABL-expressing cells and appears to play a key role in the generation of the growth inhibitory effects of IFN-alpha in CML cells.
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PMID:The p38 MAPK pathway mediates the growth inhibitory effects of interferon-alpha in BCR-ABL-expressing cells. 1135 67

The membrane redistribution and phosphorylation of focal adhesion kinase (FAK) have been reported to be important for cell migration. We previously showed that Lysophosphatidic acid (LPA) induced FAK membrane redistribution and autophosphorylation in ovarian cancer SK-OV3 cells and the signaling pathway consisting of Gi-Ras-MEKK1 mediated LPA-induced FAK membrane redistribution but not FAK autophosphorylation. We also showed that the disruption of the Gi-Ras-MEKK1 pathway led to a significant reduction in LPA-stimulated cell migration. These findings raised the question of whether LPA-induced FAK autophosphorylation was required for LPA-stimulated cell migration and what signaling mechanism was involved in LPA-induced FAK autophosphorylation. In this study, we expressed the membrane anchored wild-type FAK (CD2-FAK) in SK-OV3 cells and found that the expression of CD2-FAK greatly rescued LPA-stimulated cell migration in Gi or Ras-inhibited cells. However, Gi inhibitor pertussis toxin or dominant-negative H-Ras still significantly inhibited LPA-stimulated cell migration in cells expressing the membrane anchored FAK containing a mutation in the autophosphorylation site [CD2-FAK(Y397A)]. These results suggest that FAK autophosphorylation plays a role in LPA-stimulated cell migration. With the aid of p115RhoGEF-RGS, G12 and G13 minigenes to inhibit G12/13, we found that the G12/13 pathway was required for LPA-induced FAK autophosphorylation and efficient cell migration. Moreover, LPA activated RhoA and Rho kinase (ROCK) in a G12/13-dependent manner and their activities were required for LPA-induced FAK autophosphorylation. However, Rho or ROCK inhibitors displayed no effect on LPA-induced FAK membrane redistribution although they abolished LPA-induced cytoskeleton reorganization. Our studies show that the G12/13-RhoA-ROCK signaling pathway mediates LPA-induced FAK autophosphorylation and contributes to LPA-stimulated cell migration.
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PMID:The G12/13-RhoA signaling pathway contributes to efficient lysophosphatidic acid-stimulated cell migration. 1630 93

Previously we have shown that TGF-beta1 protects murine L929 fibroblasts from TNF/ActD-mediated cell death by inducing the expression of an extracellular matrix TNF-resistance triggering (TRT) protein. TRT promotes TNF-resistance via activation of tyrosine and serine/threonine kinases in L929 cells. To examine the presence of TRT activity in serum (designated STRT), human sera were diluted, treated with or without PMSF and subjected to sequential ammonium sulfate precipitation (ASP). Aliquots of the ASP protein fractions were coated onto 96-well plates, followed by thorough washing. When L929 cells were seeded and cultured on the wells coated with STRT proteins, these cells resisted killing by TNF, TNF/ActD, doxorubicin and serum deprivation, but not by anti-Fas/ActD, staurosporine and ActD. STRT activity was found at the 15% ASP fraction of untreated sera, but shifted to the 20% ASP fraction of PMSF-treated sera. Two likely STRT proteins of approximately 226 and 265 kDa were found in these fractions, compared to the corresponding nonfunctional ASP fractions. Functionally, STRT was inactivated by trypsin, but not by 5 M salt, various serine and/or cysteine protease inhibitors, and antibodies against fibronectin, vitronectin, C1q, histidine-rich glycoprotein, CD44, chondroitin sulfate and hyaluronic acid. STRT failed to alter the expression of proteins involved in apoptosis such as RIP, ICH-1L, BCL-X, TIAR and IkappaBalpha, and could not induce IkappaBalpha degradation. The induced TNF-resistance could be reversed by treatment of STRT-stimulated cells with testicular hyaluronidase, as well as with tyrosine kinase inhibitors tyrophostin, lavendustin A and AG-490 (a selective inhibitor of JAK2 kinase). However, the STRT function could not be blocked by the MEK kinase inhibitor PD98059 and the NF-kappaB inhibitors curcumin and a synthetic inhibitor peptide for NF-kappaB translocation. Together, our data suggest that tyrosine kinase activation is involved in the STRT-mediated resistance to TNF and TNF/ActD in L929 cells.
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PMID:Characterization of serum adhesive proteins that block tumor necrosis factor-mediated cell death. 1646 90

The control of cell growth, that is cell size, is largely controlled by mTOR (the mammalian target of rapamycin), a large serine/threonine protein kinase that regulates ribosome biogenesis and protein translation. mTOR activity is regulated both by the availability of growth factors, such as insulin/IGF-1 (insulin-like growth factor 1), and by nutrients, notably the supply of certain key amino acids. The last few years have seen a remarkable increase in our understanding of the canonical, growth factor-regulated pathway for mTOR activation, which is mediated by the class I PI3Ks (phosphoinositide 3-kinases), PKB (protein kinase B), TSC1/2 (the tuberous sclerosis complex) and the small GTPase, Rheb. However, the nutrient-responsive input into mTOR is important in its own right and is also required for maximal activation of mTOR signalling by growth factors. Despite this, the details of the nutrient-responsive signalling pathway(s) controlling mTOR have remained elusive, although recent studies have suggested a role for the class III PI3K hVps34. In this issue of the Biochemical Journal, Findlay et al. demonstrate that the protein kinase MAP4K3 [mitogen-activated protein kinase kinase kinase kinase-3, a Ste20 family protein kinase also known as GLK (germinal centre-like kinase)] is a new component of the nutrient-responsive pathway. MAP4K3 activity is stimulated by administration of amino acids, but not growth factors, and this is insensitive to rapamycin, most likely placing MAP4K3 upstream of mTOR. Indeed, MAP4K3 is required for phosphorylation of known mTOR targets such as S6K1 (S6 kinase 1), and overexpression of MAP4K3 promotes the rapamycin-sensitive phosphorylation of these same targets. Finally, knockdown of MAP4K3 levels causes a decrease in cell size. The results suggest that MAP4K3 is a new component in the nutrient-responsive pathway for mTOR activation and reveal a completely new function for MAP4K3 in promoting cell growth. Given that mTOR activity is frequently deregulated in cancer, there is much interest in new strategies for inhibition of this pathway. In this context, MAP4K3 looks like an attractive drug target since inhibitors of this enzyme should switch off mTOR, thereby inhibiting cell growth and proliferation, and promoting apoptosis.
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PMID:Nutrient-responsive mTOR signalling grows on Sterile ground. 1734 40

Transforming growth factor beta (TGFbeta) plays a critical role in connective tissue remodeling by fibroblasts during development, tissue repair, and fibrosis. We investigated the molecular pathways in the transmission of TGFbeta signals that lead to features of connective tissue remodeling, namely formation of an alpha-smooth muscle actin (alpha-SMA) cytoskeleton, matrix contraction, and expression of profibrotic genes. TGFbeta causes the activation of focal adhesion kinase (FAK), leading to JNK phosphorylation. TGFbeta induces JNK-dependent actin stress fiber formation, matrix contraction, and expression of profibrotic genes in fak+/+, but not fak-/-, fibroblasts. Overexpression of MEKK1, a kinase acting upstream of JNK, rescues TGFbeta responsiveness of JNK-dependent transcripts and actin stress fiber formation in FAK-deficient fibroblasts. Thus we propose a FAK-MEKK1-JNK pathway in the transmission of TGFbeta signals leading to the control of alpha-SMA cytoskeleton reorganization, matrix contraction, and profibrotic gene expression and hence to the physiological and pathological effects of TGFbeta on connective tissue remodeling by fibroblasts.
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PMID:FAK is required for TGFbeta-induced JNK phosphorylation in fibroblasts: implications for acquisition of a matrix-remodeling phenotype. 1740 52


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