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:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Catecholamine-stimulated lipolysis is primarily a beta-adrenergic and cAMP-dependent event. In previous studies we established that the beta(3)-adrenergic receptor (beta(3)AR) in adipocytes utilizes a unique mechanism to stimulate extracellular signal-regulated kinases 1 and 2 (ERK) by direct recruitment and activation of Src kinase. Therefore, we investigated the role of the ERK pathway in adipocyte metabolism and found that the beta(3)AR agonist CL316,243 regulates lipolysis through both cAMP-dependent protein kinase (PKA) and ERK. Inhibition of PKA activity completely eliminated lipolysis at low (subnanomolar) CL316,243 concentrations and by 75-80% at higher nanomolar concentrations. The remaining 20-25% of PKA-independent lipolysis, as well as ERK activation, was abolished by inhibiting the activity of either Src (PP2 or small interfering RNA), epidermal growth factor receptor (EGFR with AG1478 or small interfering RNA), or mitogen-activated protein kinase kinase 1 or 2 (MKK1/2 with PD098059). PD098059 inhibited lipolysis by 53% in mice as well. Finally, the effect of estradiol, a reported acute activator of ERK and lipolysis, was also totally prevented by PP2, AG1478, and PD098059. These results suggest that ERK activation by beta(3)AR depends upon Src and epidermal growth factor receptor kinase activities and is responsible for the PKA-independent portion of the lipolytic response. Together these results illustrate the distinct and complementary roles for PKA and ERK in catecholamine-stimulated lipolysis.
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PMID:Maximal beta3-adrenergic regulation of lipolysis involves Src and epidermal growth factor receptor-dependent ERK1/2 activation. 1703 47

Overexpression and/or gene amplification of c-Src and members of the epidermal growth factor receptor (EGFR/ErbB) family have been implicated in the pathogenesis of breast cancer. Although members of the EGFR family are known to form heterocomplexes with one another, c-Src has also been shown to physically interact with members of this family in breast cancer cell lines and tumors. This paper investigates the role of c-Src in modulating the physical and functional interaction between ErbB2 and ErbB3, two family members that preferentially associate with one another and together exhibit high oncogenic potential. We show that overexpressed wild-type c-Src enhances heterocomplex formation of ErbB2 and ErbB3 that results in increased basal and/or heregulin-induced activation of receptors, and their downstream intracellular effectors. Expression of a kinase-inactive form of c-Src (K(-) c-Src) or pharmacological inhibition of c-Src by PP2 negatively affects these events. Furthermore, cellular motility and anchorage-independent growth promoted by the ErbB2/ErbB3 heterocomplex are dependent upon c-Src, as demonstrated by the effects of K(-) c-Src overexpression or treatment with PP2. In contrast to previous studies that defined a role for c-Src downstream of ErbB2/ErbB3, the current work suggests an upstream mechanism, whereby c-Src enhances ErbB2/ErbB3 signaling and biological functions by positively modulating the association between ErbB2 and ErbB3.
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PMID:c-Src modulates ErbB2 and ErbB3 heterocomplex formation and function. 1717 75

In this work, we have evaluated the effect of the new discovered peptide obestatin on cell proliferation in primary cultures of human retinal epithelial cells (hRPE cells). The results showed that this peptide induced, in a dose-dependent manner, cell proliferation by MEK/ERK 1/2 phosphorylation. A sequential analysis of the obestatin transmembrane signaling pathway showed that the ERK 1/2 activity is partially blocked after preincubation of the cells with pertussis toxin (PTX), as well as by wortmannin (an inhibitor of PI3K), claphostin C (an inhibitor of PKC), and PP2 (which inhibits the non receptor tyrosine kinase Src). Upon administration of obestatin, the intracellular levels of phospho-PKCepsilon-, theta-, and micro-isoenzymes rise with different time courses, from which PKCepsilon might be responsible for ERK 1/2 response. Based on the experimental data, a signaling pathway involving the consecutive activation of Gi, PI3K, novel PKC (probably PKCepsilon), and Src for ERK 1/2 activation is proposed. These results incorporate a new mitogenic factor to the group of factors that regulate proliferation of hRPE cells.
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PMID:Obestatin-mediated proliferation of human retinal pigment epithelial cells: regulatory mechanisms. 1718 96

Orthovanadate (Na3VO4), which acts as an inhibitor of protein tyrosine phosphatases, has a various pharmacological effects including the release of arachidonic acid (AA) from cells. We investigated roles of alpha-type cytosolic phospholipase A2 (cPLA2alpha), Src family kinases (Src) and protein kinase C (PKC) in the release of AA induced by Na3VO4 from a murine fibroblast cell line, L929. C12 cells, a variant of L929 that lacks expression of cPLA2alpha, were used along with a clone of C12 cells that are stably expressing cPLA2alpha (C12-cPLA2alpha cells). In the presence of a Ca2+ ionophore (10 microM A23187), 5 and 10mM Na3VO4 synergistically stimulated AA release from L929 and C12-cPLA2alpha cells, and to a much lesser extent from control C12 cells. The release of AA by Na3VO4/A23187 was inhibited by a selective cPLA2alpha inhibitor (3 microM pyrrophenone). The release of AA by Na3VO4/A23187 was significantly inhibited by a PKC inhibitor (10 microM GF109203X), in PKC-depleted cells, by a Src inhibitor (2 microM PP2) and by an inhibitor of extracellular signal-regulated kinase 1/2 (ERK1/2) kinase (10 microM U0126). The phosphorylation of ERK1/2 was stimulated by Na3VO4, and the response was significantly decreased by inhibitors of Src, PKC and ERK1/2 kinase. Our data show that Na3VO4 stimulates AA release largely via cPLA2alpha activation in Ca2+-dependent manner, and the cross-talk between Src and PKC and the ERK-dependent pathways are involved in Na3VO4-induced AA release from L929 cells.
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PMID:Vanadate-induced activation of cytosolic phospholipase A2alpha in L929 cells: Roles of tyrosine kinase, protein kinase C, and extracellular signal-regulated kinase. 1718 53

Src family non-receptor-type tyrosine kinases regulate a wide variety of cellular events including cell cycle progression in G(2)/M phase. Here, we show that Src signaling regulates the terminal step in cytokinesis called abscission in HeLa cells. Abscission failure with an unusually elongated intercellular bridge containing the midbody is induced by treatment with the chemical Src inhibitors PP2 and SU6656 or expression of membrane-anchored Csk chimeras. By anti-phosphotyrosine immunofluorescence and live cell imaging, completion of abscission requires Src-mediated tyrosine phosphorylation during early stages of mitosis (before cleavage furrow formation), which is subsequently delivered to the midbody through Rab11-driven vesicle transport. Treatment with U0126, a MEK inhibitor, decreases tyrosine phosphorylation levels at the midbody, leading to abscission failure. Activated ERK by MEK-catalyzed dual phosphorylation on threonine and tyrosine residues in the TEY sequence, which is strongly detected by anti-phosphotyrosine antibody, is transported to the midbody in a Rab11-dependent manner. Src kinase activity during the early mitosis mediates ERK activation in late cytokinesis, indicating that Src-mediated signaling for abscission is spatially and temporally transmitted. Thus, these results suggest that recruitment of activated ERK, which is phosphorylated by MEK downstream of Src kinases, to the midbody plays an important role in completion of abscission.
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PMID:Src signaling regulates completion of abscission in cytokinesis through ERK/MAPK activation at the midbody. 1718 53

Substratum surface topography is a powerful modulator of cell behaviour, but how it influences intracellular signaling is largely unknown. We investigated the influence of microfabricated topographies on the activation of nonreceptor tyrosine kinases Src, FAK and ERK 1/2, as well as the transcription factor, Runx2, in rat osteoblasts, cultured on substrata that varied in their ability to promote bone-like tissue formation. Total tyrosine phosphorylation increased on grooves, tapered pits, and gap cornered boxes, relative to the levels found on smooth surfaces, with the greatest activity at 1 week. Src levels was higher on smooth than on any other surface, but FAK and ERK 1/2 phosphorylation were highest on groove and gap-cornered boxes up to 6 weeks. Inhibition of Src phosphorylation with PP2 inhibited FAK and ERK 1/2 phosphorylation on grooves, but had no detectable effect on either FAK or ERK 1/2 on smooth substratum. We suggest that osteoblast response to substrata with specific topographical features requires FAK-Y397-Src-Y416 complexes for ERK 1/2 phosphorylation, but on smooth surfaces, Src independent methods of ERK 1/2 activation are present.
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PMID:The effect of substratum topography on osteoblast adhesion mediated signal transduction and phosphorylation. 1721 38

Pulmonary epithelial cells are exposed to repetitive deformation during physiological breathing and mechanical ventilation. Such deformation may influence pulmonary growth, development, and barotrauma. Although deformation stimulates proliferation and activates extracellular signal-regulated kinases (ERK1/2) in human pulmonary epithelial H441 cells, the upstream mechanosensors that induce ERK activation are poorly understood. We investigated whether c-Src or focal adhesion kinase (FAK) mediates cyclic mechanical strain-induced ERK1/2 activation and proliferation in human pulmonary epithelial (NCI-H441) cells. The H441 and A549 cells were grown on collagen I-precoated membranes and were subjected to an average 10% cyclic mechanical strain at 20 cycles/min. Cyclic strain activated Src within 2 min by increasing phosphorylation at Tyr(418), followed by rapid phosphorylation of FAK at Tyr(397) and Tyr(576) and ERK1/2 at Thr(202)/Tyr(204) (n = 5, P < 0.05). Twenty-four (A549 cells) and 24-72 h (H441 cells) of cyclic mechanical strain increased cell numbers compared with static culture. Twenty-four hours of cyclic strain also increased H441 FAK, Src, and ERK phosphorylation without affecting total FAK, Src, or ERK protein. The mitogenic effect was blocked by Src (10 micromol/l PP2 or short interfering RNA targeted to Src) or MEK (50 micromol/l PD-98059) inhibition. PP2 also blocked strain-induced phosphorylation of FAK-Tyr(576) and ERK-Thr(202)/Tyr(204) but not FAK-Tyr(397). Reducing FAK by FAK-targeted short interfering RNA blocked mechanical strain-induced mitogenicity and significantly attenuated strain-induced ERK activation but not strain-induced Src phosphorylation. Together, these results suggest that repetitive mechanical deformation induced by ventilation supports pulmonary epithelial proliferation by a pathway involving Src, FAK, and then ERK signaling.
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PMID:Src and focal adhesion kinase mediate mechanical strain-induced proliferation and ERK1/2 phosphorylation in human H441 pulmonary epithelial cells. 1721 24

Chromogranin A (CgA) is associated with microglial activation cascades implicated in neurodegeneration in Alzheimer's, Pick's and Parkinson's diseases. In primary rat microglia, CgA-mediated inducible nitric oxide (iNOS) expression, nitric oxide (NO) production, mitochondrial depolarisation and apoptosis were inhibited by PP2 (Src kinase inhibitor). CgA-mediated iNOS expression and NO production were also inhibited by U0126 (MEK inhibitor), but mitochondrial depolarisation and apoptosis were not. PP2 inhibited ERK phosphorylation; therefore, Src mediates CgA-induced ERK phosphorylation leading to iNOS expression and NO production. Glutamate release induced by CgA was independent of both pathways. These findings provide insights into the way microglia are activated by CgA and the microglial signalling mechanisms associated with neurological disorders such as Alzheimer's disease.
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PMID:Chromogranin A activates diverse pathways mediating inducible nitric oxide expression and apoptosis in primary microglia. 1726 11

Insulin-like growth factor-I (IGF-I) is required for the growth of oligodendrocytes, although the underlying mechanisms are not fully understood. Our aim was to investigate the role of phosphatidylinositol 3-kinase (PI3K), mitogen-activated protein kinase kinase (MEK1), and Src family tyrosine kinases in IGF-I-stimulated proliferation of oligodendrocyte progenitors. IGF-I treatment increased the proliferation of cultured oligodendrocyte progenitors as determined by measuring incorporation of [(3)H]-thymidine and bromodeoxy-uridine (BrdU). IGF-I stimulated a transient phosphorylation of 3-phosphoinositide-dependent kinase-1 (PDK1) and extracellular signal-regulated kinases (ERK1/2) (targets of MEK1), as well as a rapid and sustained activation of Akt (a target of PI3K). Furthermore, inhibitors of PI3K (LY294002 and Wortmannin), MEK1 (PD98059 and U0126), and Src family tyrosine kinases (PP2) decreased IGF-I-induced proliferation, and blocked ERK1/2 activation. LY294002, Wortmannin and PP2 also blocked Akt activation. To further determine whether Akt is required for IGF-I stimulated oligodendrocyte progenitor proliferation, cultures were infected with adenovirus vectors expressing dominant-negative mutants of Akt or treated with pharmacological inhibitors of Akt. All treatments reduced IGF-I-induced oligodendrocyte progenitor proliferation. Our data indicate that stimulation of oligodendrocyte progenitor proliferation by IGF-I requires Src-like tyrosine kinases as well as the PI3K/Akt and MEK1/ERK signaling pathways.
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PMID:IGF-I-induced oligodendrocyte progenitor proliferation requires PI3K/Akt, MEK/ERK, and Src-like tyrosine kinases. 1734 61

In this report, we demonstrate the application of Au nanoparticles in the electrochemical detection of protein phosphorylation. The method is based on the labeling of a specific phosphorylation event with Au nanoparticles, followed by electrochemical detection. The phosphorylation reaction is coupled with the biotinylation of the kinase substrate using a biotin-modified adenosine 5'-triphosphate [gamma]-biotinyl-3,6,9-trioxaundecanediamine (ATP) as the co-substrate. When the phosphorylated and biotinylated kinase substrate is exposed to streptavidin-coated Au nanoparticles, the high affinity between the streptavidin and biotin resulted in the attachment of Au nanoparticles on the kinase substrate. The electrochemical response obtained from Au nanoparticles enables monitoring the activity of the kinase and its substrate, as well as the inhibition of small molecule inhibitors on protein phosphorylation. We determined the activity of Src non-receptor protein tyrosine kinase, p60(c-Src) and protein kinase A in combination with their highly specific substrate peptides Raytide EL and Kemptide, respectively. The detection limits for Raytide EL and Kemptide were determined as 5 and 10 microM, (S/N=3), and the detection limits for the kinase activity of p60(c-Src) and protein kinase A (PKA) were determined as 5 and 10 U mL(-1), (S/N=3), respectively. Tyrosine kinase reactions were also performed in the presence of a well-defined inhibitor, 4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo[3,4-d]pyrimidine (PP2), and its negative control molecule, 4-amino-7-phenylpyrazol[3,4-d] pyrimidine (PP3), which had no inhibition effect. Based on the dependency of Au nanoparticle signal on inhibitor concentration, IC(50) value, half-maximal inhibition of the inhibitors was estimated. IC(50) values of PP2, genistein and herbimycin A to p60(c-Src) were detected as 5 nM, 25 microM and 900 nM, respectively. The inhibition of PKA activity on Kemptide using ellagic acid was monitored with an IC(50) of 3.5 microM. The performance of the biosensor was optimized including the kinase reaction, incubation with streptavidin-coated Au nanoparticles, and the small molecule inhibitors. Kinase peptide-modified electrochemical biosensors are promising candidates for cost-effective kinase activity and inhibitor screening assays.
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PMID:Gold nanoparticle-based electrochemical detection of protein phosphorylation. 1738 90


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