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)

Insulin-like growth factor binding protein 4 (IGFBP4/BP4) gene expression plays an important role in the transition from proliferation to differentiation of a human colon cancer cell line, CaCo2. We recently cloned and identified multiple cis elements (including putative binding sites for activator protein 1 (AP-1) and specificity proteins (Sps) ) in the promoter of human BP4 gene, and measured a significant upregulation of the promoter activity in response to c-Jun. We therefore examined the role of the single AP-1 site (-869/-863) and other cis elements, in regulating the expression of hBP4 gene, in the current studies. Deletion of a 25 bp sequence from -872 to -848, which contains the AP-1 site, significantly reduced BP4 promoter activity by approximately 50%. Surprisingly, mutation of the AP-1 site did not produce significant alteration in the activity of the BP4 promoter. However, mutation of 7 bp (5'-TGCTGCA) at the 3' end of the AP-1 site resulted in significantly decreasing the promoter activity by >50%. Proteins bound to the 25 bp probe (-872/-848) could be supershifted by antibodies specific for JunD and Sp3 in an EMSA. JunD binding was abolished on mutation of the AP-1 site and Sp3 binding was abolished on mutation of the 7 bp at -861/-855; binding of the purified Sp3 protein to the 25 bp probe was similarly abolished on mutation of the newly discovered Sp3 binding site (TGCTGCA). BP4 promoter activity was upregulated in insect cells in response to Sp3 expression, confirming a functional importance of the novel Sp3 binding site. These studies suggest that the Sp3 binding site, rather than the AP-1 site, may be playing a significant role in regulating the expression of IGFBP4 gene in CaCo2 cells.
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PMID:Identification of a novel SP3 binding site in the promoter of human IGFBP4 gene: role of SP3 and AP-1 in regulating promoter activity in CaCo2 cells. 1476 71

Telomerase is essential for immortalization of most human cancer cells. Expression of the core telomerase RNA (hTR) and reverse transcriptase (hTERT) subunits is mainly regulated by transcription. However, hTR transcriptional regulation remains poorly understood. We previously showed that the core hTR promoter is activated by Sp1 and is repressed by Sp3. Here, we show that the mitogen-activated protein kinase kinase kinase 1 (MEKK1)/c-Jun-NH(2)-kinase (JNK) pathway represses hTR expression by a mechanism that involves Sp1 and Sp3. Promoter activity was induced by the JNK inhibitor SP600125 and was repressed by activated MEKK1. Repression by MEKK1 was blocked by SP600125 or enhanced by coexpression of wild-type but not phosphoacceptor mutated JNK. SP600125 treatment also increased levels of endogenous hTR. Mutations in the hTR promoter Sp1/Sp3 binding sites attenuated SP600125-mediated promoter induction, whereas coexpression of MEKK1 with Sp3 enhanced hTR promoter repression. Chromatin immunoprecipitation showed that levels of immunoreactive Sp1 associated with the hTR promoter were low in comparison with Sp3 in control cells but increased after JNK inhibition with a reciprocal decrease in Sp3 levels. No corresponding changes in Sp1/Sp3 protein levels were detected. Thus, JNK represses hTR promoter activity and expression, apparently by enhancing repression through Sp3.
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PMID:Transcriptional repression of telomerase RNA gene expression by c-Jun-NH2-kinase and Sp1/Sp3. 1645 90

We analyzed in detail the proximal promoter of transcription factor Sp3, which expands 281 bp from the translational start. This sequence contains putative binding sites for Sp1, NF-Y, NF-1, Myb, AP-1 and E2F transcription factors. In this work, we further explored the role of these boxes on the regulation of the Sp3 gene. Gel-shift and competition assays showed specific binding of NF-1, Myb, AP-1 and E2F. Furthermore, chromatin immunoprecipitation assays demonstrated that Sp1, Sp3, NF-Y, NF-1, c-Myb, B-Myb, c-Jun and E2F1 actually occupied the Sp3 promoter in HeLa cells. Transient transfections and luciferase assays revealed activation of the Sp3 proximal promoter upon overexpression of NF-1, c-Myb, B-Myb, c-Jun and c-Fos, and repression after overexpression of E2F/DP1. Point mutation of the binding sites for NF1, Myb, AP1 and E2F and cell incubation with specific siRNAs further confirmed the role of these transcription factors in the regulation of the Sp3 promoter. The regulation of the endogenous Sp3 gene was also observed at the mRNA level when the studied transcription factors were overexpressed or knocked down by siRNA incubation. These results help to explain the complex regulation of the Sp3 gene, which depends, at least in part, on the relative amount of Sp1, Sp3, NF-Y, NF-1, c-Myb, B-Myb, AP-1, and E2F proteins in the cell.
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PMID:Transcriptional regulation of the 5'-flanking region of the human transcription factor Sp3 gene by NF-1, c-Myb, B-Myb, AP-1 and E2F. 1834 22