Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P05412 (c-Jun)
 11,453 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A number of cytokines, including basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), oncostatin M (OSM), IL-6, and tumor necrosis factor alpha (TNF-alpha), have been postulated to have a role in the pathogenesis of Kaposi's sarcoma (KS). The proliferative effects of bFGF and OSM may be via their reported activation of the c-Jun NH2-terminal kinase (JNK) signaling pathway in KS cells. We now report that KS cells express a recently identified focal adhesion kinase termed RAFTK which appears in other cell systems to coordinate surface signals between cytokine and integrin receptors and the cytoskeleton as well as act downstream to modulate JNK activation. We also report that the tyrosine kinase receptor FLT-4, present on normal lymphatic endothelium, is robustly expressed in KS cells. Treatment of KS cells with VEGF-related protein (VRP), the ligand for the FLT-4 receptor, as well as with the cytokines bFGF, OSM, IL-6, VEGF, or TNF-alpha resulted in phosphorylation and activation of RAFTK. Following its activation, there was an enhanced association of RAFTK with the cytoskeletal protein paxillin. This association was mediated by the hydrophobic COOH-terminal domain of the kinase. Furthermore, JNK activity was increased in KS cells after VEGF or VRP stimulation. We postulate that in these tumor cells RAFTK may be activated by a diverse group of stimulatory cytokines and facilitate signal transduction to the cytoskeleton and downstream to the growth promoting JNK pathway.
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PMID:Cytokine signaling through the novel tyrosine kinase RAFTK in Kaposi's sarcoma cells. 912 25

Hepatocyte Growth Factor (HGF) exerts its biological effects via binding and activating a transmembrane protein tyrosine kinase receptor known as c-Met. Previous studies from our laboratory demonstrated that c-met gene expression is inducible by its own ligand (HGF). However, the molecular mechanism(s) involved in this process are unknown. The present study was carried out to address this question. Transfection of various c-met-CAT promoter constructs into the mouse hepatocellular carcinoma cell line Hepa 1-6 in combination with electrophoretic mobility shift assays (EMSA) identified the responsive element as an activated protein-1 (AP-1) binding site (TGAGTCA) within the c-met core promoter region at position -158 to -152. The c-met AP-1 element binds specifically to AP-1 protein as verified by supershift assays. EMSA studies and mutational analyses of the promoter region also revealed that the members of the Sp family of transcription factors (Sp-1 and Sp-3) bind to the c-met Sp-1 element (located at position -124) which is adjacent to the AP-1 site. We show that Sp binding dampens binding of AP-1 to its cognate site in the c-met promoter region. Stimulation of Hepa 1-6 cells with HGF resulted in a rapid and dramatic enhancement of the AP-1 binding activity as well as an overall increase in the level of AP-1 protein. Cotransfection of AP-1 expression vectors (c-Fos plus c-Jun) with c-met promoter constructs resulted in stimulation of c-met promoter activity. We found that transactivation of the c-met promoter by AP-1 can be blocked by Curcumin, an inhibitor of AP-1. Moreover, we found that the induction of the endogenous c-met gene by HGF is inhibited by the addition of Curcumin. The results demonstrate that the HGF-induced transcription of the c-met gene by HGF is, at least in part, due to activation of the AP-1 pathway.
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PMID:Transcriptional activation of the hepatocyte growth factor receptor (c-met) gene by its ligand (hepatocyte growth factor) is mediated through AP-1. 1071

UV-induced melanogenesis is a well known physiological response of human skin exposed to solar radiation; however, the signaling molecules involved in the stimulation of melanogenesis in melanocytes following UV exposure remain unclear. In this study we induced melanogenesis in vitro in normal human epidermal melanocytes using a single irradiation with UVA at 1 kJ/m2 and examined the potential involvement of mitogen-activated protein kinases (MAPK) as UVA-responsive signaling molecules in those cells. UVA irradiation did not affect the proliferation of melanocytes, but it did increase tyrosinase mRNA expression, which reached a maximum level 4 hr after UVA irradiation. The amount of tyrosinase protein, as quantitated by immunoblotting, was also increased at 24 hr following UVA irradiation. Among the MAPK examined, extracellular signal-related kinase (ERK) 1/2 was phosphorylated within 15 min of UVA irradiation, but no such phosphorylation was observed for c-Jun N-terminal kinases (JNK) or p38. Accordingly, the activity of ERK1/2 was also increased shortly after UVA irradiation. These responses of ERK1/2 to UVA irradiation were markedly inhibited when cells were pre-treated with N-acetyl-L-cysteine, an antioxidant, or with suramin, a tyrosine kinase receptor inhibitor. The formation of (6-4)photoproducts or cyclobutane pyrimidine dimers was not detected in cellular DNA after UVA irradiation. These findings suggest that a single UVA irradiation-induced melanogenesis is associated with the activation of ERK1/2 by upstream signals that originate from reactive oxygen species or from activated tyrosine kinase receptors, but not from damaged DNA.
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PMID:Possible involvement of ERK 1/2 in UVA-induced melanogenesis in cultured normal human epidermal melanocytes. 1131 Jul 89

The human transmembrane mucin MUC4 is aberrantly expressed in 75% of pancreatic ductal adenocarcinomas, whereas no expression is found in normal pancreas. Therefore MUC4 appears as a useful biological marker for the diagnosis of ductal adenocarcinomas. Since rat Muc4 was shown to interact with ErbB-2 tyrosine kinase receptor and to either promote cell survival and differentiation or cell proliferation, it is postulated that MUC4 may also participate in pancreatic carcinogenesis. Our aim was to investigate in parallel the role of the Ets factor PEA3 in MUC4 and ErbB-2 transcriptional regulation in pancreatic cancer cells. Two MUC4-expressing WD (well-differentiated) (CAPAN-1 and -2) and one MUC4-non-expressing poorly differentiated (PANC-1) cell lines were used. The three cell lines express ErbB-2 at different levels. By co-transfection and site-directed mutagenesis, we show that PEA3 is a transactivator of the MUC4 promoter and that the -216 and -2368 PEA3 binding sites of the MUC4 promoter are essential. We also demonstrate that PEA3 acts in synergy with c-Jun and specificity protein 1 to transactivate the proximal region of the MUC4 promoter and increase MUC4 mRNA levels in WD cells. These results suggest that MUC4 is a new target gene of the Ets factor PEA3 in pancreatic cancer cells. In contrast, PEA3 represses the transcriptional activity of two fragments of the ErbB-2 promoter in a dose-dependent manner and decreases the endogenous ErbB-2 mRNA levels in WD cell lines. Thus, PEA3, by its capacity to up-regulate the epithelial marker MUC4 and to down-regulate the ErbB-2 oncogene, appears as a key regulator of the differentiation/proliferation balance in pancreatic cancer cells.
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PMID:The antagonistic regulation of human MUC4 and ErbB-2 genes by the Ets protein PEA3 in pancreatic cancer cells: implications for the proliferation/differentiation balance in the cells. 1546 91

Previous studies have demonstrated increased expression and phosphorylation of tyrosine kinase receptor (TrkA, TrkB) in lumbosacral DRG after chronic (6 weeks) spinal cord (T8-T10) injury. This study examined the effects of acute SCI (48 hours, 2 weeks) on TrkA and TrkB expression and phosphorylation, and CREB and c-Jun expression in DRG. A significant increase in the number of TrkA- (1.5-3-fold; P < or = 0.05), TrkB- (1.3-2.0-fold; P < or = 0.05), and phosphorylated Trk (pTrk)-immunoreactive (1.5-3-fold; P < or = 0.05) cells was observed in the L1, L6, and S1 DRG 48 hours, 2, or 6 weeks after SCI. A significant increase in the number of phosphorylated (p-) CREB-immunoreactive cells was observed in the L1, L2, L6, and S1 DRG 48 hours, 2, or 6 weeks after SCI. The largest changes in p-CREB-immunoreactivity were in L1 and L2 DRG (10-fold; P <or= 0.01) at 48 hours after SCI; however, changes were modest in bladder afferent neurons. After SCI, the overall number of c-Jun-immunoreactive cells in L1, L2, and S1 DRG was dramatically increased (3-10-fold; P < or = 0.01); however, only a low percentage of bladder afferent cells expressed c-Jun-IR before or after SCI. In summary, these results suggest that TrkA or TrkB may be involved in reorganization of micturition pathways after SCI. However, CREB or c-Jun may not be downstream transcription factors in Trk-mediated signaling cascades in micturition reflex pathways after SCI but may play a role in other, nonbladder SCI-induced changes.
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PMID:Spinal cord injury-induced expression of TrkA, TrkB, phosphorylated CREB, and c-Jun in rat lumbosacral dorsal root ganglia. 1561 95

In response to injury, peripheral neuronal cells initiate complex signalling cascades to promote survival and regeneration. In the present study, we used a model of experimental injury in the rat pheochromocytoma cell line PC12 to investigate receptor signals that lead to neurite outgrowth. Nerve growth factor (NGF) dose-dependently induced sprouting and the expression of the NGF receptors Trk tyrosine kinase receptor (TrkA) and p75 neurotrophin receptor (p75(NTR)) as well as Fas and Fas ligand. Neurite regeneration was decreased by chemical inhibition of TrkA, but not p75(NTR), and by the Fas inhibitor protein Fas-Fc. The mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinases (JNKs) were activated in response to NGF and both significantly contributed to neurite re-growth. Interestingly, otherwise apoptotic Fas ligation supported neuronal recovery exclusively via JNKs and promoted sprouting parallel to NGF. These findings suggest a novel signal integration from the NGF and Fas pathways in the JNK axis of MAPK signalling, where JNKs function as "physiological" mediators of normally apoptotic signals.
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PMID:c-Jun N-terminal kinases mediate Fas-induced neurite regeneration in PC12 cells. 1869 25

Neuropilin-1 (NRP-1) is a non-tyrosine kinase receptor for vascular endothelial growth factor (VEGF) that was recently found to play a role in tumor functions. Previous studies demonstrated that NRP-1 was overexpressed in a number of human tumors, including glioblastoma (GBM). However, the role of NRP-1 in glioma progression has yet to be adequately elucidated. Thus, we examined the expression of NRP-1 in human glioma cell lines using Western blotting, and cell cycle distribution and proliferation by transfection of the U373 cell line with NRP-1 short interference RNA (siRNA). Results showed NRP-1 siRNA to significantly reduce NRP-1 gene expression, decrease in vitro cell proliferation and induce cell apoptosis in cultured glioma cells, along with the accumulation of cells in the G1 phase and a decrease in cells in the S phase. Our results further revealed that NRP-1 knockdown decreased the expression levels of Bcl-2 family proteins and deactivated extracellular signal-regulated kinase (ERK) and c-Jun-N-terminal kinase (JNK)/mitogen-activated protein kinase (MAPK) signaling pathways, closely associated with cancer progression. Thus, our results provide a molecular mechanism for the effect of NRP-1 in tumors, rendering NRP-1 an attractive candidate as a therapeutic target in certain types of cancer, such as GBM.
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PMID:RNA interference targeting NRP-1 inhibits human glioma cell proliferation and enhances cell apoptosis. 2184 23

Epidermal growth factor receptor (EGFR) has a crucial role in cell differentiation and proliferation and cancer, and its expression appears to be up-regulated when arylsulfatase B (ARSB or GalNAc-4-sulfatase) is reduced. ARSB removes 4-sulfate groups from the nonreducing end of dermatan sulfate and chondroitin 4-sulfate (C4S), and its decreased expression has previously been reported to inhibit the activity of the ubiquitous protein-tyrosine phosphatase, nonreceptor type 11 (SHP2 or PTPN11). However, the mechanism by which decline in ARSB leads to decline in SHP2 activity is unclear. Here, we show that SHP2 binds preferentially C4S, rather than chondroitin 6-sulfate, and confirm that SHP2 activity declines when ARSB is silenced. The reduction in ARSB activity, and the resultant increase in C4S, increased the expression of EGFR (Her1/ErbB1) in human prostate stem and epithelial cells. The increased expression of EGFR occurred after 1) the decline in SHP2 activity, 2) enhanced c-Jun N-terminal kinase (JNK) activity, 3) increased nuclear DNA binding by c-Jun and c-Fos, and 4) EGFR promoter activation. In response to exogenous EGF, there was increased bromodeoxyuridine incorporation, consistent with enhanced cell proliferation. These findings indicated that ARSB and chondroitin 4-sulfation affect the activation of an important dual phosphorylation threonine-tyrosine kinase and the mRNA expression of a critical tyrosine kinase receptor in prostate cells. Restoration of ARSB activity with the associated reduction in C4S may provide a new therapeutic approach for managing malignancies in which EGFR-mediated tyrosine kinase signaling pathways are active.
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PMID:Decline in arylsulfatase B expression increases EGFR expression by inhibiting the protein-tyrosine phosphatase SHP2 and activating JNK in prostate cells. 2979 38