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)

The transglutaminase I (TGase I) gene encodes an enzyme that catalyzes the cross-linking of structural proteins involved in the formation of the cornified envelope during squamous cell differentiation. To identify DNA elements important for the transcriptional control of the TGase I gene, we analyzed the ability of a 2.9-kilobase pair (kb) upstream regulatory region to control the expression of a reporter gene in vivo and in vitro. Transgenic mice bearing the pTG(-2.9kb)CAT construct exhibited the same pattern of tissue-specific expression of CAT as reported for TGase I. Deletion analysis in transiently transfected rabbit tracheal epithelial cells indicated that two sequences from bp -490 to -470 and from -54 to -37 are involved in the activation of TGase I transcription. Point mutation analysis and mobility shift assays showed that the sequence located between -54 and -37 is a functional Sp1-like transcription element. Sp1 and Sp3, but not Sp2, are part of nuclear protein complexes from differentiated RbTE cells binding to this site. The element TGATGTCA between bp -490 and -470 is contained in a larger 22-bp palindrome and resembles the consensus cAMP response element-binding protein (CREB)/AP-1 element recognized by dimeric complexes of members of the CREB, ATF, Fos, and Jun families. Mutations in this sequence greatly reduced promoter activity. Supershift analysis identified CREB1, JunB, c-Fos, Fra-1, and c-Jun in protein complexes isolated from differentiated rabbit tracheal epithelial cells binding to this site. Our study shows that the Sp1- and CREB/AP-1-like sites act in concert to stimulate transcription of the TGase I gene. The 2.9-kb promoter region could guide expression of specific genes in the granular layer of the epidermis and could be useful in gene therapy.
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PMID:Regulation of the transglutaminase I gene. Identification of DNA elements involved in its transcriptional control in tracheobronchial epithelial cells. 992 Sep 44

To examine regulatory mechanisms of sheep interferon tau (oIFNtau) gene expression, potential enhancer/silencer elements of the oIFNtau gene were examined using a transient transfection system with oIFNtau gene-chloramphenicol acetyltransferase (oIFNtau-CAT) reporter constructs in human choriocarcinoma cells, JEG3. Experiments with 5'-deletion constructs revealed that the upstream regions from bases -654 to -607 and from bases -606 to -555 were essential for oIFNtau gene expression. In a heterologous transcriptional system in which the upstream regions of oIFNtau were inserted in front of simian virus 40 (SV40) promoter, the regions between bases -654 and -555 were determined as being the enhancer region required for oIFNtau-SV40-CAT transactivation. A subsequent study with the oIFNtau-CAT constructs lacking the upstream region between bases -542 and -124 revealed that, in addition to the further upstream region between bases -1000 and -654, the sequences from bases -543 to -452 seemed to act as silencer regions. The oIFNtau-CAT constructs with site-specific mutagenesis revealed that multiple enhancer elements existed between bases -654 and -555 of the oIFNtau gene. On the basis of nucleotide sequence analysis, there are numerous sites between bases -654 and -555 to which potential transcriptional factors, AP-1, GATA and GATA-related proteins, could bind. Furthermore, gel mobility-shift assays revealed that AP-1 or other nuclear factors could bind to these elements. In co-transfection studies, the expression of c-Jun plus c-Fos enhanced the transactivation of oIFNtau-CAT but the expression of GATA-1, GATA-2 or GATA-3 did not. Taken together, these results suggest that the upstream region between bases -654 and -555 could be considered as the enhancer region for oIFNtau gene transactivation.
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PMID:Identification of a functional transcriptional factor AP-1 site in the sheep interferon tau gene that mediates a response to PMA in JEG3 cells. 1035 63

The cell cycle inhibitor protein p21(WAF1/Cip1) (p21) is a critical downstream effector in p53-dependent mechanisms of growth control and p53-independent pathways of terminal differentiation. We have recently reported that the transforming growth factor-beta pathway-specific Smad3 and Smad4 proteins transactivate the human p21 promoter via a short proximal region, which contains multiple binding sites for the ubiquitous transcription factor Sp1. In the present study we show that the Sp1-occupied promoter region mediates transactivation of the p21 promoter by c-Jun and the related proteins JunB, JunD, and ATF-2. By using gel electrophoretic mobility shift assays we show that this region does not contain a binding site for c-Jun. In accordance with the DNA binding data, c-Jun was unable to transactivate the p21 promoter when overexpressed in the Sp1-deficient Drosophila-derived SL2 cells. Coexpression of c-Jun and Sp1 in these cells resulted in a strong synergistic transactivation of this promoter. In addition, a chimeric promoter consisting of six tandem high affinity Sp1-binding sites fused with the CAT gene was transactivated by overexpressed c-Jun in HepG2 cells. The above data propose functional cooperation between c-Jun and Sp1. Physical interactions between the two factors were demonstrated in vitro by using GST-Sp1 hybrid proteins expressed in bacteria and in vitro transcribed-translated c-Jun. The region of c-Jun mediating interaction with Sp1 was mapped within the basic region leucine zipper domain. In vivo, functional interactions between c-Jun and Sp1 were demonstrated using a GAL4-based transactivation assay. Overexpressed c-Jun transactivated a chimeric promoter consisting of five tandem GAL4-binding sites only when coexpressed with GAL4-Sp1-(83-778) fusion proteins in HepG2 cells. By utilizing the same assay, we found that the glutamine-rich segment of the B domain of Sp1 (Bc, amino acids 424-542) was sufficient for c-Jun-induced transactivation of the p21 promoter. In conclusion, our data support a mechanism of superactivation of Sp1 by c-Jun, which is based on physical and functional interactions between these two transcription factors on the human p21 and possibly other Sp1-dependent promoters.
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PMID:c-Jun transactivates the promoter of the human p21(WAF1/Cip1) gene by acting as a superactivator of the ubiquitous transcription factor Sp1. 1050 25

Transcription factors of the AP-1/ATF family, including c-Fos, c-Jun, and ATF-2, play an important role in the regulation of cell proliferation and differentiation, and changes in their levels and/or activities may contribute to oncogenesis. We analyzed the alterations of AP-1/ATF transcription factors upon immortalization and transformation in a panel of cell lines derived from rat embryo fibroblast (REF) cells. The tumorigenic E1A + cHa-ras cells are characterized by high and constitutive DNA binding activities of AP-1, in contrast to nontransformed cells and the E1A cells. The expression of c-fos and c-jun genes was affected differently by the oncogenic transformation. By using antibodies to c-Jun and c-Fos proteins in electrophoretic mobility shift assays (EMSA), we showed that E1A + cHa-ras transformants did not contain c-Fos under any condition of cell cultivation and growth factor stimulation, whereas c-Jun was constitutively upregulated. In the absence of c-fos gene expression, c-Fos protein appears to be replaced by proteins of Fos family (Fra-1) and ATF family (ATF-2 and ATFa). To determine the possible mechanisms of c-fos downregulation in E1A + cHa-ras transformants we have obtained populations of geneticin-resistant clones containing integrated reporter construct -711fos-CAT and its mutants in serum-responsive element (SRE) and cAMP-responsive element (CRE). Data obtained show that the mutations within the SRE lead to a manifold activation of fos-CAT expression. This allows to suggest that c-fos downregulation in E1A + cHa-ras transformants is provided by a negative control mediated through the SRE regulatory region. The profound differences in regulation and composition of transcription factors of the AP-1 family probably play a pivotal role in the transformation of REF cells by E1A and cHa-ras oncogenes.
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PMID:E1A + cHa-ras transformed rat embryo fibroblast cells are characterized by high and constitutive DNA binding activities of AP-1 dimers with significantly altered composition. 1054 28

JEM-1 is a novel gene whose mRNA expression in acute promyelocytic leukemia (APL) is induced by retinoid treatments. The gene product, a 45 kDa basic nuclear factor containing a leucine repeat, was transiently expressed in HeLa or COS-7 cells and immunocharacterized within the nuclei in fine punctuated structures which increase in size after cell transfection. Jem-1 was not expressed in the nucleoli. Experimental deletion of peptide domains of Jem-1 (JemDelta331-400 and Jem DeltaL179-206) showed that its C-terminal sequence (Thr331 --> Leu400) is required for nuclear translocation, while the leucine repeat domain (Arg179 --> Glu206) has no influence on subcellular localization. The Jem-1 protein was not detected in the PML-containing nuclear bodies or in speckled structures containing the splicing factor SC-35. In contrast it was localized in the nucleus in structures containing activator protein-1 (AP-1). DNA mobility shift assays showed that the in vitro translated Jem protein interacts neither with the DNA binding site of AP-1, nor directly with in vitro co-translated c-Fos or/and c-Jun proteins bound to this specific sequence. Interestingly, Jem-1-1 increased substantially the transcriptional activity of c-Jun (three-fold) and more strongly that of ectopically co-expressed c-Fos and c-Jun (five- to six-fold), as measured by a CAT reporter gene driven by a heterologous promoter containing the AP-1 binding site of the human collagenase gene. These synergistic effects were strongly Jem-1 dose-dependent. However, Jem-1 alone showed no activity on the collagenase promoter. A deletion of the leucine repeat of Jem-1 (Arg179 --> Glu206) did not diminish the enhancer capacity of Jem-1 on AP-1 activity. In contrast, the enhanced AP-1 activity was abrogated when Jem-1 was deleted of its C-terminus (Thr331 --> Leu400). We conclude that the 45 kDa nuclear product of the JEM-1 gene has features of a novel transcription cofactor, which is enhancing AP-1 activity without directly interacting with c-Jun or c-Fos proteins. Possible implications of these findings for APL cell maturation are discussed.
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PMID:JEM-1, a novel nuclear co-factor: localisation and functional interaction with AP-1. 1060 19

Activator protein-1 (AP1) regulates the promoter activity of a large number of genes associated with developmental, proliferative, inflammatory, and homeostatic processes in human connective tissue cells. Some of these genes (e.g., cyclooxygenase-2) are regulated by the protein kinase C (PKC) inhibitor, calphostin C (CalC). We examined whether CalC could indeed induce AP1 and AP1 gene transactivation (c-jun) in human chondrocytes. Exploratory studies confirmed the anti-PKC effects of CalC, as equal molar concentrations of CalC blocked the PMA-induced translocation of PKC-alpha from the cytosolic to the membrane fraction. CalC induction of AP1, as judged by gel-shift analysis, using a consensus AP1 oligonucleotide, was biphasic with an initial increase (maximum 4 h), followed by a decline, reaching its nadir after 16 h, and finally a major upregulation phase at 24 h. Maximum induction of AP-1 was reached at a concentration of 250 nmol/L of CalC. CalC did not block PMA-induced AP1 synthesis. Gel-shift analysis in the presence of specific antibodies to c-Jun, JunB, JunD, c-Fos, and CREB/ATF showed that the AP1 complexes were probably c-Jun/c-Jun, c-Fos/c-Jun, c-Fos/JunB, or c-Jun/JunB dimers. Northern blot analysis confirmed that c-jun, junB, and c-Fos were the principal proto-oncogenes induced by CalC. To confirm that c-jun induction occurs at the transcriptional level and to examine the role of the AP1 site present in the c-jun promoter in the induction of c-jun by CalC, we performed transient transfections of c-jun promoter-CAT constructs harboring either wild-type (WT) AP1 regulatory element sites or mutant AP1 sites. CalC (250 nmol/L) induced a marked increase in CAT activity (i.e., promoter activation) with WT AP1 c-jun promoter-CAT plasmids, but the response was completely abrogated when using constructs where the AP1 site was mutated. PMA produced similar results, but the induction of the WT AP1 c-jun promoter-CAT plasmid was smaller. CalC (250 nmol/L) inhibited MAPK (p42/44) activity while stimulating c-Jun N-terminal kinase activity in a time-frame coincident with the activation of AP1. We conclude that CalC induces signaling pathways that activate AP1 and transactivate genes harboring AP1 enhancer sites independent of PKC-alpha.
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PMID:Calphostin C induces AP1 synthesis and AP1-dependent c-jun transactivation in normal human chondrocytes independent of protein kinase C-alpha inhibition: possible role for c-jun N-terminal kinase. 1061 45

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

DNA methylation is an important component of the epigenetic control of genome functions. Understanding the regulation of the DNA Methyltransferase (dnmt1) gene expression is critical for comprehending how DNA methylation is coordinated with other critical biological processes. In this paper, we investigate the transcriptional regulatory region of the human dnmt1 gene using a combination of RACE, RNase protection analysis and CAT assays. We identified one major and three minor transcription initiation sites in vivo (P1-P4), which are regulated by independent enhancers and promoter sequences. The minimal promoter elements of P1, P2 and P4 are mapped within 256 bp upstream of their respective transcription initiation sites. P1 is nested within a CG-rich area, similar to other housekeeping genes, whereas P2-P4 are found in CG-poor areas. Three c-Jun-dependent enhancers are located downstream to P1 and upstream to P2-P4, thus providing a molecular explanation for the responsiveness of dnmt1 to oncogenic signals that are mediated by the Ras-c-Jun oncogenic signaling pathway.
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PMID:Transcriptional regulation of the human DNA Methyltransferase (dnmt1) gene. 1072 35

Estrogen exerts a variety of effects not only on female reproductive organs but also on nonreproductive organs, including adipose tissue. Estrogen inhibits obesity triggered by ovariectomy in rodents. We studied the mechanism underlying this estrogen-dependent inhibition of obesity. Estrogen markedly decreased the amounts of fat accumulation and lipoprotein lipase (LPL) mRNA as well as triglyceride accumulation in genetically manipulated 3T3-L1 adipocytes stably expressing the estrogen receptor (ER). A pLPL(1980)-CAT construct, along with an ER expression vector, was introduced into differentiated 3T3-L1 cells, and CAT activities were determined. ER, mostly ligand-dependently, inhibited the basal LPL promoter activity by 7-fold. We searched the LPL promoter for an estrogen-responsive suppressive element by employing a set of 5'-deletion mutants of the pLPL-CAT reporter. Although there was no classical estrogen response element, it was demonstrated that an AP-1-like TGAATTC sequence located at (-1856/-1850) was responsible for the suppression of the LPL gene transcription by estrogen. An electrophoretic mobility shift assay probed with the TGAATTC sequence demonstrated formation of a specific DNA-nuclear protein complex. Interestingly, this complex was not affected by the addition of any antibodies against ER, c-Jun, c-Fos, JunB, or JunD. Because this TGAATTC element responded to phorbol ester and overexpression of CREB-binding protein abrogated the suppressive effect of estrogen on the LPL promoter, we conclude that a unique protein that is related to the AP-1 transcription factor families may be involved in the complex that binds to the TGAATTC element.
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PMID:Estrogen suppresses transcription of lipoprotein lipase gene. Existence of a unique estrogen response element on the lipoprotein lipase promoter. 1075 56

Matrix metalloproteinases (MMPs) are thought to play crucial roles in tumor invasion and metastasis. Because we have shown that EBV latent membrane protein 1 (LMP1) enhances MMP-9 expression by activation of nuclear factor (NF)-kappaB and activator protein (AP)-1 (T. Yoshizaki, et al., Proc. Natl. Acad. Sci. USA, 95: 3621-3626, 1998), we therefore tested whether up-regulation of MMP-9 by LMP1 could be correlated with enhanced invasiveness of tumor cells in vitro. Whether aspirin and sodium salicylate could reduce invasiveness and whether LMP1 could enhance MMP-9 expression in tumors grown in nude mice were also tested. C33A cells stably expressing LMP1 had increased expression of MMP-9 and showed greater invasion through reconstituted basement membrane compared with vector-transfected C33A cells (P < 0.02). Treatment with aspirin or sodium salicylate inhibited invasiveness of the LMP1-expressing C33A cells (P < 0.03) and suppressed both the LMP1-induced MMP-9 expression in zymographic analyses and LMP1-induced MMP-9 promoter activity in CAT reporter assays (P < 0.01). Endogenous MMP-2 levels were unaffected by either drug. Both drugs repressed the CAT activity of the truncated MMP-9 promoter construct, which only contained a binding site for AP-1, to the basal level (P < 0.05). Moreover, EMSA indicated that the effects of the salicylates were through the inhibition of not only NF-kappaB but also AP-1 binding activity. Inhibitory effect of salicylates could be reversed by p50/p65 subunits of NF-kappaB or c-Jun overexpression. The inhibitory effect of aspirin on NF-kappaB activity was attributable to the inhibition of IkappaB kinase activity. Finally, tumors derived from C33A cells stably expressing LMP1 grown in nude mice showed enhanced MMP-9 levels compared with tumors derived from vector-transfected C33A cells. This enhancement was inhibited by treatment of the mice with aspirin. These results suggest that aspirin may be able to suppress invasion and metastasis of EBV-associated tumors that express LMP1 by suppression of MMP-9.
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PMID:Aspirin inhibits tumor cell invasiveness induced by Epstein-Barr virus latent membrane protein 1 through suppression of matrix metalloproteinase-9 expression. 1081 Nov 39


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