Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of the present study was to determine the mechanisms involved in estrogen actions in cultured rat Sertoli cells. RT-PCR detected transcripts for the estrogen receptors ESR1 and ESR2 in cultured immature Sertoli cells and in the testis of 15-, 28-, and 120-day-old rats. The expression of ESR1 and ESR2 was confirmed in Sertoli cells by immunofluorescence and Western blot. Immunohistochemistry with cryosections of testes from immature and adult rats revealed that ESR1 is present in Sertoli, Leydig, and some peritubular myoid cells, and ESR2 is present in multiple cell types, including germ cells. Treatment of Sertoli cells with 17beta-estradiol (E(2)) induced a translocation of ESR1 and ESR2 to the plasma membrane and a concomitant phosphorylation of MAPK3/1. Both effects reached a maximum after 10 min and were blocked by PP2, an inhibitor of the SRC family of protein tyrosine kinases, and by the antiestrogen ICI 182,780 (ICI). MAPK3/1 phosphorylation was also decreased in the presence of AG 1478, an inhibitor of the epidermal growth factor receptor (EGFR) kinase, and in the presence of MAP2K1/2 inhibitor UO126. Treatment with E(2) for 24 h increased the incorporation of [methyl-(3)H]thymidine, which was blocked by ICI. These results indicate that E(2) activates an SRC-mediated translocation of estrogen receptors to the plasma membrane, which results in the activation of EGFR and the mitogen-activated protein kinase signaling pathway. In addition, activation of ESR1 and/or ESR2 by E(2) is involved in proliferation of immature Sertoli cells. The estrogen actions in Sertoli cells might be a key step mediating cellular events important for spermatogenesis and fertility.
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PMID:17beta-estradiol induces the translocation of the estrogen receptors ESR1 and ESR2 to the cell membrane, MAPK3/1 phosphorylation and proliferation of cultured immature rat Sertoli cells. 1792 26

Activating mutations in fibroblast growth factor receptor 3 (FGFR3) cause several human skeletal dysplasias as a result of attenuation of cartilage growth. It is believed that FGFR3 inhibits chondrocyte proliferation via activation of signal transducers and activators of transcription (STAT) proteins, although the exact mechanism of both STAT activation and STAT-mediated inhibition of chondrocyte growth is unclear. We show that FGFR3 interacts with STAT1 in cells and is capable of activating phosphorylation of STAT1 in a kinase assay, thus potentially serving as a STAT1 kinase in chondrocytes. However, as demonstrated by western blotting with phosphorylation-specific antibodies, imaging of STAT nuclear translocation, STAT transcription factor assays and STAT luciferase reporter assays, FGF does not activate STAT1 or STAT3 in RCS chondrocytes, which nevertheless respond to a FGF stimulus with potent growth arrest. Moreover, addition of active STAT1 and STAT3 to the FGF signal, by means of cytokine treatment, SRC-mediated STAT activation or expression of constitutively active STAT mutants does not sensitize RCS chondrocytes to FGF-mediated growth arrest. Since FGF-mediated growth arrest is rescued by siRNA-mediated downregulation of the MAP kinase ERK1/2 but not STAT1 or STAT3, our data support a model whereby the ERK arm but not STAT arm of FGF signaling in chondrocytes accounts for the growth arrest phenotype.
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PMID:STAT1 and STAT3 do not participate in FGF-mediated growth arrest in chondrocytes. 1819 89

Fibroblast growth factor (FGF2), but not vascular endothelial growth factor (VEGF), upregulates endothelial nitric oxide synthase (eNOS) protein expression, at least partially, via activation of extracellular signal-regulated kinase 2/1 (ERK2/1) in ovine fetoplacental artery endothelial (oFPAE) cells. Herein we further investigated the temporal effects of FGF2 and VEGF on other signalling pathways including members (Jun N-terminal kinase JNK1/2 and p38MAPK) of mitogen-activated protein kinases (MAPK), phosphatidylinositol-3 kinase/v-akt murine thymoma viral oncogene homologue 1 (PI3K/AKT1), and the tyrosine kinase c-SRC, and examined if either one or more of these pathways play a role in the differential regulation of eNOS by FGF2 and VEGF. We first confirmed that in oFPAE cells, FGF2, but not VEGF, increased eNOS protein. FGF2 stimulated eNOS protein in a time- and concentration-dependent manner, which also depended on cell density. FGF2 provoked sustained (5min to 12h) whereas VEGF only stimulated transient (5min) ERK2/1 phosphorylation. FGF2 was 1.7-fold more potent in stimulating ERK2/1 phosphorylation than VEGF. FGF2 and VEGF only transiently activated JNK1/2 and AKT1 within 5min; however, FGF2 was a stronger stimulus than VEGF. FGF2 and VEGF did not significantly activate p38MAPK at 5min; however, VEGF stimulated p38MAPK phosphorylation at 60min. VEGF but not FGF2 significantly stimulated c-SRC phosphorylation. Inhibitors of MEK-ERK2/1 (PD98059), JNK1/2 (SP600125) and PI3K (wortmannin), but not p38MAPK (SB203580) and SRC (PP2), decreased the FGF2-increased eNOS protein expression. Thus, the FGF2-induced eNOS protein expression requires activation of multiple signalling pathways including ERK2/1, JNK1/2 and PI3K/AKT1. Differences in intensity and temporal patterns of activation of these pathways by FGF2 and VEGF may account for their differential effects on eNOS expression in OFPAE cells.
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PMID:Differential activation of multiple signalling pathways dictates eNOS upregulation by FGF2 but not VEGF in placental artery endothelial cells. 1857 18

The role of androgen and androgen receptors (ARs) in males has been well established. This steroid and its receptor also exist in follicles, but their functions are still unclear. In this study, using a culture system containing a low dose of hypoxanthine, we revealed the positive contribution of testosterone to oocyte meiotic resumption. By performing ultracentrifugation to allow clear visualization of porcine germinal vesicles, our results provide evidence that mitogen-activated protein kinase (MAPK) in the oocyte itself but not in cumulus cells was activated before germinal vesicle breakdown (GVBD) after testosterone treatment. We further explored the signal cascade of testosterone-triggered GVBD and showed significant contributions of AR to testosterone-induced MAPK activation and GVBD. By using a potent and selective inhibitor of SRC and detecting activation of the kinase, we found that testosterone activated SRC in oocytes but not in cumulus cells and that SRC (as an essential upstream molecule of MAPK) mediated this testosterone- and AR-promoted reinitiation of meiosis. The present findings propose an undefined signaling pathway and suggest the potential competence of testosterone for meiotic resumption in mammalian oocytes.
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PMID:Testosterone potentially triggers meiotic resumption by activation of intra-oocyte SRC and MAPK in porcine oocytes. 1866 51

EGFR (ErbB1) and ErbB2 receptors stimulate several intracellular signaling pathways in non-small-cell lung cancer (NSCLC). Adenocarcinomas (AC) and squamous cell carcinomas (SCC) are NSCLC subtypes with distinct clinico-pathological features, and responses to ErbB-targeted inhibitors treatment. To evaluate the causes of these differences, tissue microarrays with samples from NSCLC patients (189 AC and 56 SCC) were used to study EGFR and ErbB2 expression and phospho-activation of ERK1/2, AKT, STAT3 and SRC ErbB-mediators by immunohistochemistry and Western blot, and EGFR and ErbB2 gene amplification by FISH. EGFR expression was higher in SCC than in AC (P<0.001), while ErbB2 showed similar low levels. Phosphorylated (p) ERK, pAKT, pSTAT3 and pSRC levels were prevalent in AC (P< or =0.002). EGFR levels and signaling mediators activation were differentially associated with each of the pathologies. Whereas in AC the expression and amplification of EGFR were linked to AKT activation (P< or =0.050), in SCC its expression was correlated with pSTAT3 (P=0.024). In addition, pSTAT3 was correlated with pERK and pAKT only in AC (P< or =0.045). Biomarker levels were also differentially associated with the clinico-pathologic variables. In AC, EGFR and pSRC increasing scores correlated with female sex and the smoking habit (P< or =0.008), while ErbB2 amplification increased with advanced age and tumor stage (P< or =0.047), and pERK1/2 and pSTAT3 levels correlated with early tumor stage (P< or =0.045). In SCC, EGFR amplification was stronger in younger patients (P=0.013), pERK1/2 in the older ones (P=0.050), and pSTAT3 amplification was stronger in women (P=0.001). These data support that AC and SCC lung tumors are distinct entities at the molecular level, and that their signaling status in combination with their clinico-pathologic variables may be considered for differential targeted therapies.
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PMID:Differential ErbB receptor expression and intracellular signaling activity in lung adenocarcinomas and squamous cell carcinomas. 1904 92

Novel therapeutic agents targeting the epidermal growth factor receptor (EGFR) have improved outcomes for a subgroup of patients with colorectal, lung, head and neck, and pancreatic cancers. In these tumors, the EGFR activation turns on at least five different signaling pathways (RAS/mitogen-activated protein kinase, phospholipase C, phosphatidylinositol 3-kinase/AKT, signal transducer and activator of transcription, and SRC/FAK pathways), which are intimately interconnected, and frequent mutations involving either the receptor itself or downstream effectors have been found. Up to now, it seems that alterations at the EGFR level has major importance in EGFR tyrosine kinase inhibitor response, whereas modifications of downstream effectors could lead to treatment resistance. Furthermore, our understanding of the mechanism of the EGFR network activation provides new hypotheses on potential new anticancer drugs that may be effective.
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PMID:Mutations and response to epidermal growth factor receptor inhibitors. 1922 18

Estrogen-related receptor (ERRalpha) plays a critical role in basal and cAMP-induced expression of the human surfactant protein-A (SP-A) gene in lung type II cells through direct binding to an ERR response element (ERRE, 5'-TGACCTTA-3') within its 5'-flanking region. Furthermore, protein kinase A (PKA) up-regulates ERRalpha activation of the hSP-A promoter. In the present study, using cultured human fetal lung type II cells, we observed that cAMP enhanced ERRalpha phosphorylation and nuclear expression levels. cAMP/PKA stimulation of ERRalpha activation of the SP-A promoter was blocked by the PKA inhibitor, H89, whereas the MAPK P38 inhibitor, SB203580, and the MAPK kinase inhibitor, PD98059, had negligible to modest effects. This suggests that cAMP acts selectively through PKA to increase ERRalpha transcriptional activity. Of several coactivators tested, steroid receptor coactivator 2 (SRC-2) had the most pronounced effect to increase ERRalpha transcriptional activity at the SP-A promoter; this was enhanced by cotransfection with PKA catalytic subunit (PKAcat). Interestingly, SRC-2, ERRalpha, and PKAcat in type II cell nuclear extracts interacted at the ERRE; this was enhanced by cAMP and inhibited by H89. cAMP increased in vivo binding of PKAcat and SRC-2 to the ERRE genomic region in lung type II cells. In mutagenesis studies, three serines (S87, S114, and S277) were found to be critical for PKA and SRC-2 induction of ERRalpha transcriptional activity. Collectively, these findings indicate that cAMP/PKA signaling enhances ERRalpha phosphorylation and nuclear localization, recruitment to the SP-A promoter, and interaction with PKAcat and SRC-2, resulting in the up-regulation of SP-A gene transcription.
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PMID:cAMP enhances estrogen-related receptor alpha (ERRalpha) transcriptional activity at the SP-A promoter by increasing its interaction with protein kinase A and steroid receptor coactivator 2 (SRC-2). 1926 43

Although activating mutations of fibroblast growth factor receptor 3 (FGFR3) are frequent in bladder tumors, little information is available on their specific effects in urothelial cells or the basis for the observed mutation spectrum. We investigated the phenotypic and signaling consequences of three FGFR3 mutations (S249C, Y375C, and K652E) in immortalized normal human urothelial cells (TERT-NHUC) and mouse fibroblasts (NIH-3T3). In TERT-NHUC, all mutant forms of FGFR3 induced phosphorylation of FRS2alpha and ERK1/2, but not AKT or SRC. PLCgamma1 phosphorylation was only observed in TERT-NHUC expressing the common S249C and Y375C mutations, and not the rare K652E mutation. Cells expressing S249C and Y375C FGFR3 displayed an increased saturation density, related to increased proliferation and viability. This effect was significantly dependent on PLCgamma1 signaling and undetectable in cells expressing K652E FGFR3, which failed to phosphorylate PLCgamma1. In contrast to TERT-NHUC, expression of mutant FGFR3 in NIH-3T3 resulted in phosphorylation of Src and Akt. In addition, all forms of mutant FGFR3 were able to phosphorylate Plcgamma1 and induce morphological transformation, cell proliferation, and anchorage-independent growth. Our results indicate that the effects of mutant FGFR3 are both cell type specific and mutation specific. Mutant FGFR3 may confer a selective advantage in the urothelium by overcoming normal contact inhibition of proliferation.
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PMID:Mutant fibroblast growth factor receptor 3 induces intracellular signaling and cellular transformation in a cell type- and mutation-specific manner. 1974 90

Protein phosphorylation is an important step in many biological processes, such as cell cycles, membrane transport, apoptosis, etc. In order to obtain more useful information about protein phosphorylation, it is necessary to develop a robust, stable, and accurate approach to predict phosphorylation sites. Although there exist a number of approaches to predict phosphorylation sites, such as those based on neural network and the support vector machine, they only use a single classifier. In general, the prediction results obtained by these approaches are not very stable and robust. In this paper, we design a new classifier ensemble approach called Bagging-AdaBoost ensemble (BAE) for the prediction of eukaryotic protein phosphorylation sites, which incorporates the bagging technique and the AdaBoost technique into the classifier framework to improve the accuracy, stability, and robustness of the final result. To our knowledge, this is the first time in which a combined bagging and boosting ensemble approach is applied to predict phosphorylation sites. Our prediction system based on BAE focuses on six kinase families: CDK, CK2, MAPK, PKA, PKC, and SRC. BAE achieves good performance in these six families, and the accuracies of the prediction system for these families are 0.8634, 0.8721, 0.8542 , 0.8537, 0.8052, and 0.7432, respectively.
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PMID:Identifying protein-kinase-specific phosphorylation sites based on the Bagging-AdaBoost ensemble approach. 2021 87

We report here that in the mouse embryonic gonads in addition to gonadal somatic cells, primordial germ cells (PGCs) the precursors of adult gametes, express estrogen receptor alpha (ERalpha) and that through this receptor, 17-beta-estradiol (E2) is able to modulate in such cells molecular signalling known to be crucial for their development. We demonstrated that PGCs from 11.5 to 12.5 days post coitum (dpc) mouse embryos express ERalpha transcripts and protein and that at concentrations of 10(-8)M E2 stimulates rapid (within 20 min) about 4-fold AKT (Ser473) and 3-fold ERK2 (Thr202/Tyr204) and SRC (Tyr418) phosphorylation. In addition, the E2 stimulatory effects were associated with increased phosphorylation of the KIT receptor (Tyr568/570). While the ER antagonist ICI182780 was able to abolish these effects, AKT phosphorylation induced by E2 was also inhibited by the PI3K inhibitor LY294002 and the SRC family inhibitor PP2. This latter was also able to abolish the increased phosphorylation of KIT and ERKs caused by E2. Taken together these results suggest that E2 may modulate via ERalpha non-genomic signalling/phosphorylation cascade in mouse PGCs. This was also supported by the finding that PGCs express MNAR, a scaffold protein that regulate ER activation in other cell types. Finally, we found that when PGCs were cultured in the presence of 10(-8)M E2 a significant ICI inhibitable increase of their number occurred. The present study provides evidence for novel direct non-genomic actions of estrogens on PGCs and suggests that these cells can represent a potential target for estrogens and estrogenic compounds during the early stages of embryo development in mammals.
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PMID:Rapid estrogen signalling in mouse primordial germ cells. 2038 Aug 32


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