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

Exposure to sources of UV radiation, such as sunlight, induces a number of cellular alterations that are highly dependent on its ability to affect gene expression. Among them, the rapid activation of genes coding for two subfamilies of proto-oncoproteins, Fos and Jun, which constitute the AP-1 transcription factor, plays a key role in the subsequent regulation of expression of genes involved in DNA repair, cell proliferation, cell cycle arrest, death by apoptosis, and tissue and extracellular matrix remodeling proteases. Besides being regulated at the transcriptional level, Jun and Fos transcriptional activities are also regulated by phosphorylation as a result of the activation of intracellular signaling cascades. In this regard, the phosphorylation of c-Jun by UV-induced JNK has been readily documented, whereas a role for Fos proteins in UV-mediated responses and the identification of Fos-activating kinases has remained elusive. Here we identify p38 MAPKs as proteins that can associate with c-Fos and phosphorylate its transactivation domain both in vitro and in vivo. This phosphorylation is transduced into changes in its transcriptional ability as p38-activated c-Fos enhances AP1-driven gene expression. Our findings indicate that as a consequence of the activation of stress pathways induced by UV light, endogenous c-Fos becomes a substrate of p38 MAPKs and, for the first time, provide evidence that support a critical role for p38 MAPKs in mediating stress-induced c-Fos phosphorylation and gene transcription activation. Using a specific pharmacological inhibitor for p38alpha and -beta, we found that most likely these two isoforms mediate UV-induced c-Fos phosphorylation in vivo. Thus, these newly described pathways act concomitantly with the activation of c-Jun by JNK/MAPKs, thereby contributing to the complexity of AP1-driven gene transcription regulation.
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PMID:Phosphorylation of c-Fos by members of the p38 MAPK family. Role in the AP-1 response to UV light. 1570 45

Kaposi's sarcoma-associated herpesvirus (KSHV) in vitro target cell infection is characterized by the expression of the latency-associated genes ORF 73 (LANA-1), ORF 72, and K13 and by the transient expression of a very limited number of lytic genes such as lytic cycle switch gene ORF 50 (RTA) and the immediate early (IE) lytic K5, K8, and v-IRF2 genes. During the early stages of infection, several overlapping multistep complex events precede the initiation of viral gene expression. KSHV envelope glycoprotein gB induces the FAK-Src-PI3K-RhoGTPase (where FAK is focal adhesion kinase) signaling pathway. As early as 5 min postinfection (p.i.), KSHV induced the extracellular signal-regulated kinase 1 and 2 (ERK1/2) via the PI3K-PKCzeta-MEK pathway. In addition, KSHV modulated the transcription of several host genes of primary human dermal microvascular endothelial cells (HMVEC-d) and fibroblast (HFF) cells by 2 h and 4 h p.i. Neutralization of virus entry and infection by PI-3K and other cellular tyrosine kinase inhibitors suggested a critical role for signaling molecules in KSHV infection of target cells. Here we investigated the induction of ERK1/2 by KSHV and KSHV envelope glycoproteins gB and gpK8.1A and the role of induced ERK in viral and host gene expression. Early during infection, significant ERK1/2 induction was observed even with low multiplicity of infection of live and UV-inactivated KSHV in serum-starved cells as well as in the presence of serum. Entry of UV-inactivated virus and the absence of viral gene expression suggested that ERK1/2 induction is mediated by the initial signal cascade induced by KSHV binding and entry. Purified soluble gpK8.1A induced the MEK1/2 dependent ERK1/2 but not ERK5 and p38 mitogen-activated protein kinase (MAPK) in HMVEC-d and HFF. Moderate ERK induction with soluble gB was seen only in HMVEC-d. Preincubation of gpK8.1A with heparin or anti-gpK8.1A antibodies inhibited the ERK induction. U0126, a selective inhibitor for MEK/ERK blocked the gpK8.1A- and KSHV-induced ERK activation. ERK1/2 inhibition did not block viral DNA internalization and had no significant effect on nuclear delivery of KSHV DNA during de novo infection. Analyses of viral gene expression by quantitative real-time reverse transcriptase PCR revealed that pretreatment of cells with U0126 for 1 h and during the 2-h infection with KSHV significantly inhibited the expression of ORF 73, ORF 50 (RTA), and the IE-K8 and v-IRF2 genes. However, the expression of lytic IE-K5 gene was not affected significantly. Expression of ORF 73 in BCBL-1 cells was also significantly inhibited by preincubation with U0126. Inhibition of ERK1/2 also inhibited the transcription of some of the vital host genes such as DUSP5 (dual specificity phosphatase 5), ICAM-1 (intercellular adhesion molecule 1), heparin binding epidermal growth factor, and vascular endothelial growth factor that were up-regulated early during KSHV infection. Several MAPK-regulated host transcription factors such as c-Jun, STAT1alpha, MEF2, c-Myc, ATF-2 and c-Fos were induced early during infection, and ERK inhibition significantly blocked the c-Fos, c-Jun, c-Myc, and STAT1alpha activation in the infected cells. AP1 transcription factors binding to the RTA promoter in electrophoretic mobility shift assays were readily detected in the infected cell nuclear extracts which were significantly reduced by ERK inhibition. Together, these results suggest that very early during de novo infection, KSHV induces the ERK1/2 to modulate the initiation of viral gene expression and host cell genes, which further supports our hypothesis that beside the conduit for viral DNA delivery into the cytoplasm, KSHV interactions with host cell receptor(s) create an appropriate intracellular environment facilitating infection.
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PMID:ERK1/2 and MEK1/2 induced by Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) early during infection of target cells are essential for expression of viral genes and for establishment of infection. 1605 24

Lot1, a zinc finger transcription factor acting as a tumor suppressor gene on tumoral cells, is highly expressed during brain development. In developing rat cerebellum, Lot1 expression is high in cerebellar granule cells (CGC), a neuronal population undergoing postnatal neurogenesis. The time course of Lot1 cerebellar expression closely matches the expression of pituitary adenylate cyclase-activating polypeptide (PACAP) receptors coupled to adenylyl cyclase. The aim of this study was to ascertain whether Lot1 expression is regulated by cAMP-dependent pathways and to identify mechanisms of Lot1 activation in CGC cultures. Our results show that Lot1 expression in CGC is cAMP-dependent, as treatments with either forskolin or PACAP-38 induced an increase in its expression at both the mRNA and protein levels. This effect on Lot1 expression was mimicked by dibutyryl cAMP and suppressed by protein kinase A and MEK inhibitors. In parallel, we found that treatments with forskolin and PACAP-38 in precursor CGC inhibited bromodeoxyuridine incorporation by 25 and 35%, respectively, indicating a negative effect on neuronal precursor proliferation. Luciferase reporter analysis and mutagenesis of the Lot1 promoter region indicated a crucial role of the AP1-binding site (located at -268 bp) in cAMP-induced Lot1 transcription. In addition, cotransfection experiments indicated that the c-Fos/c-Jun heterodimer is responsible for cAMP-dependent Lot1 transcriptional activation. In conclusion, our data demonstrate that, in CGC, Lot1 is under the transcriptional control of cAMP through an AP1 site regulated by the c-Fos/c-Jun heterodimer and suggest that this gene may be an important element of the cAMP-mediated pathway that regulates neuronal proliferation through the protein kinase A-MEK signaling cascade.
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PMID:Cyclic AMP-mediated regulation of transcription factor Lot1 expression in cerebellar granule cells. 1606 85

The signal transduction of human 12(S)-lipoxygenase and the regulation of gene activation, induced by epidermal growth factor (EGF), are discussed in this review article. Treatment of human epidermoid carcinoma A431 cells with EGF induces the gene expression of human 12(S)-lipoxygenase, and two Sp1 binding sites residing at -158 to -150 bp and -123 to -114 bp are essential in the mediation of EGF induction of the 12(S)-lipoxygenase gene. EGF induces MAPK activation in cells, followed by the activation of AP1. Thus, the biosynthesis of c-Jun is enhanced, which subsequently interacts with Sp1. c-Jun on Sp1/c-Jun complex is then recruited to gene promoter through the binding of Sp1 to Sp1-binding sites on gene promoter. Subsequent transactivation of the promoter activation of the human 12(S)-lipoxygenase gene is induced. In addition to the functional role of Sp1 in gene regulation of 12(S)-lipoxygenase, recent studies have also demonstrated that Sp1 acting as an anchor protein to recruit transcription factor c-Jun is essential for growth factor and/or phorbol ester-induced expression of several genes.
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PMID:Transcription factor Sp1 functions as an anchor protein in gene transcription of human 12(S)-lipoxygenase. 1612

To elucidate the possible effect of NFkappaB on radioresistance, we used the osteosarcoma cell line Saos2, stably expressing the NFkappaB constitutive inhibitor, mIkappaB (Saos2-mIkappaB) or stably transfected with the empty vector (Saos2-EV). Ionizing radiation induced "intrinsic" apoptosis in Saos2-mIkappaB cells but not in Saos2-EV control cells, with intact NFkappaB activity. We find as expected, that this NFkappaB activity was enhanced following irradiation in the Saos2-EV control cells. On the other hand, inhibition of NFkappaB signaling in Saos2-mIkappaB cells led to the upregulation of the pro-apoptotic systems, such as Bax protein and c-Jun N-terminal Kinase (JNK)/c-Jun/AP1 signaling. Inhibition of NFkappaB resulted in decreased expression of the DNA damage protein GADD45beta, a known inhibitor of JNK. Subsequently, JNK activation of c-Jun/AP-1 proteins increased radiation-induced apoptosis in these mutants. Radiation-induced apoptosis in Saos2-mIkappaB cells was inhibited by the JNK specific inhibitor SP600125 as well as by Bcl-2 over-expression. Furthermore, release of cytochrome-c from mitochondria was increased and caspase-9 and -3 were activated following irradiation in Saos2-mIkappaB cells. Antisense inhibition of GADD45beta in Saos2-EV cells significantly enhanced apoptosis following irradiation. Our results demonstrate that radioresistance of Saos2 osteosarcoma cells is due to NFkappaB-mediated inhibition of JNK. Our study brings new insight into the mechanisms underlying radiation-induced apoptosis of osteosarcoma, and may lead to development of new therapeutic strategies against osteosarcoma.
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PMID:Increased radiation-induced apoptosis of Saos2 cells via inhibition of NFkappaB: a role for c-Jun N-terminal kinase. 1616 36

VIP exerts a spectrum of effects as a potent anti-inflammatory factor. In addition, VIP increases expression of MUC2, a major intestinal secretory mucin. We therefore investigated the effects of VIP on the promoter activity of the 5'-flanking region of the MUC2 gene. VIP activated MUC2 transcription in human colonic epithelial cells via cAMP signaling to ERK and p38. cAMP/Epac/Rap1/B-Raf signaling was not involved in MUC2 reporter activation. Furthermore, activation of MUC2 transcription was independent of many of the reported downstream effectors of G protein-coupled receptors, such as PKC, Ras, Raf, Src, calcium, and phosphoinositide 3-kinase. VIP induced cAMP response element-binding protein (CREB)/ATF1 phosphorylation, and this was prevented by treatment with inhibitors of either MEK or p38 and by PKA and MSK1 inhibitor H89. CREB/ATF1 and c-Jun were shown to bind to an oligonucleotide encompassing a distal, conserved CREB/AP1 site in the 5'-flanking region of the MUC2 gene, and this cis element was shown to mediate promoter reporter activation by VIP. This study has identified a new, functional cis element within the MUC2 promoter and also a new pathway regulating MUC2 expression, thus providing further insight into the molecular mechanism of VIP action in the colon. These findings are relevant to the normal biology of the colonic mucosa as well as to the development of VIP as a therapeutic agent for treatment of inflammatory bowel disease.
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PMID:Vasoactive intestinal peptide upregulates MUC2 intestinal mucin via CREB/ATF1. 1622 28

The cytoskeleton is a dynamic network that undergoes restructuring during various cellular events, influencing cell proliferation, differentiation, and apoptosis. Here, we report that accumulation of c-Jun, a member of the AP1 family of transcription factors that play a key role in normal and aberrant cell growth, dramatically increases upon depolymerization of the cytoskeleton, and that, unexpectedly, this increase is controlled translationally. Depolymerization of the actin or microtubule network induces an increase in c-Jun accumulation with no corresponding increase in c-Jun mRNA or in the half-life of the c-Jun protein, but rather in the translatability of its transcript. This increase is mediated by the untranslated regions (UTRs) of c-Jun mRNA, and is not dependent on activated mitogen-activated protein kinase pathways. This novel mechanism of c-Jun regulation might be relevant to physiological conditions in which c-Jun plays a pivotal role.
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PMID:The cytoskeletal network controls c-Jun translation in a UTR-dependent manner. 1624 75

Nectin-2, a major protein component of the adherens junctions (AJs), is found between Sertoli cells and germ cells in the seminiferous epithelium. Recent studies have shown that the expression of nectin-2 gene in testis is crucial to maintain normal spermatogenesis since male knockout mice lacking nectin-2 gene are sterile and possess morphologically abnormal spermatozoa. However, the molecular mechanisms governing its basal transcription remain poorly understood. By the use of Sertoli and germ cell-lines (TM4 and GC-2spd(ts) cells, respectively) in transient transfection studies, we showed that the minimal mouse nectin-2 promoter was located between nucleotides -316 and -211 (relative to the translation start site). Two putative Sp1 motifs and one each of the CRE, AP1, and AP2 motifs were identified within this region. Mutational studies showed that these two Sp1 motifs cooperated synergistically with the CRE motif, but not the AP1 and AP2 motifs, to regulate nectin-2 gene transcription in both TM4 and GC-2spd(ts) cells. By EMSAs, we found that an AP-1 consensus sequence was able to inhibit DNA-protein complex formation with the CRE motif, suggesting an interaction between the AP-1 transcription factor (c-Jun) and CREB within the CRE motif. Overexpressions of CREB and c-Jun, but not c-Fos, also significantly increased the promoter activity, which suggests that CREB and c-Jun are the crucial transcription factors involved in regulating nectin-2 gene transcription. Chromatin immunoprecipitation assay has shown that, in vivo, CREB, c-Jun, and Sp1 family proteins are bound to the mouse nectin-2 promoter. Analysis of the staged tubules has confirmed that the cyclic expressions of CREB and nectin-2 coincide with the event of adherens junction restructuring between Sertoli cells and germ cells. The cross-talk between CREB, c-Jun, and Sp1 family protein is believed to be a major transcription machinery to drive nectin-2 expression in Sertoli cells.
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PMID:Nectin-2 expression in testicular cells is controlled via the functional cooperation between transcription factors of the Sp1, CREB, and AP-1 families. 1625 13

To better understand the structure and function of the myostatin's gene promoter region in sheep, we cloned and sequenced a 1.517 kb fragment containing the 5'-regulatory region of the sheep myostatin gene (GenBank accession number is AY918121). The promoter sequence consists of three TATA boxes, one CAAT box, and eight putative E-boxes. Some putative muscle growth response elements for Octamer-binding factor 1(Octamer), Activator protein 1(AP1), Growth factor independence 1 zinc finger protein (Gfi-1B), Myocyte enhancer factor 2 (MEF2), Muscle-specific Mt binding site (MTBF), Glucocorticoid response elements (GRE) and Progesterone receptor binding site (PRE) were detected. Some of the motifs are conserved as compared to with that in the goat, bovine and porcine myostatin promoters. However, some differences were also found.
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PMID:Cloning and sequence analysis of myostatin promoter in sheep. 1628 20

The molecular mechanisms for the anti-inflammatory activity of phenanthroindolizidine alkaloids were examined in an in vitro system mimicking acute inflammation by studying the suppression of lipopolysaccharide (LPS)/interferon-gamma (IFNgamma)-induced nitric oxide production in RAW264.7 cells. Two of the phenanthroindolizidine alkaloids, NSTP0G01 (tylophorine) and NSTP0G07 (ficuseptine-A), exhibited potent suppression of nitric oxide production and did not show significant cytotoxicity to the LPS/IFNgamma-stimulated RAW264.7 cells, in contrast to their respective cytotoxic effects on cancer cells. Tylophorine was studied further to investigate the responsible mechanisms. It was found to inhibit the induced protein levels of tumor necrosis factor-alpha, inducible nitric-oxide synthase (iNOS), and cyclooxygenase (COX)-II. It also inhibited the activation of murine iNOS and COX-II promoter activity. However, of the two common responsive elements of iNOS and COX-II promoters, nuclear factor-kappaB (NF-kappaB) and adaptor protein (AP)1, only AP1 activation was inhibited by tylophorine in the LPS/IFNgamma-stimulated RAW264.7 cells. Further studies showed that the tylophorine enhanced the phosphorylation of Akt and thus decreased the expression and phosphorylation levels of c-Jun protein, thereby causing the subsequent inhibition of AP1 activity. Furthermore, the tylophorine was able to block mitogen-activated protein/extracellular signal-regulated kinase kinase 1 activity and its downstream signaling activation of NF-kappaB and AP1. Thus, NSTP0G01 exerts its anti-inflammatory effects by inhibiting expression of the proinflammatory factors and related signaling pathways.
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PMID:Anti-inflammatory mechanisms of phenanthroindolizidine alkaloids. 1633 92


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