Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.31.1 (micrococcal nuclease)
 2,818 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have analyzed the chromatin structure of the porcine tumor necrosis factor gene locus (TNF-alpha and TNF-beta). Nuclei from porcine peripheral blood mononuclear cells were digested with different nucleases. As assessed with micrococcal nuclease, the two TNF genes displayed slightly faster digestion kinetics than bulk DNA. Studies with DNaseI revealed distinct DNaseI hypersensitive sites (DH-sites) within the porcine TNF locus. Four DH-sites could be observed in the promoter and mRNA leader regions of the TNF-beta gene. Two DH-sites could be observed for the TNF-alpha gene, one located in the promoter region close to the TATA-box and the other site in intron 3. This pattern of DH-sites was present independently of the activation state of the cells. Interestingly in a porcine macrophage-like cell line, we found that the TNF-alpha promoter DH-site disappeared and another DH-site appeared in the region of intron 1. Additionally, the DH-site of intron 3 could be enhanced by PMA-stimulation in these cells. TNF-beta sites were not detected in this cell line. However, DH-sites were totally absent in fibroblasts (freshly isolated from testicles) and in porcine kidney cells (PK15 cell line) both of which do not transcribe the TNF genes. Therefore, the pattern of DH-sites corresponds to the transcriptional activity of analyzed cells.
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PMID:Chromatin structure and DNase I hypersensitivity in the transcriptionally active and inactive porcine tumor necrosis factor gene locus. 157 96

Fas ligand (FasL/CD95L/TNFSF6), a member of the tumor necrosis factor family, initiates apoptosis in lymphoid and nonlymphoid tissues by binding to its receptor Fas (CD95/TNFRSF6). Although the transcriptional control of TNFSF6 gene expression is subjected to intense study, the role of its chromatin organization and accessibility to the transcriptional machinery is not known. Here, we determined the chromatin organization of TNFSF6 gene 5' regulatory regions. Using the indirect end-labeling technique, a unique region named HSS1 and encompassing nucleotides -189 to +185 according to the transcriptional start site, was identified throughout a 20-kilobase nucleosomal DNA domain surrounding the promoter. The HSS1 region displayed hypersensitivity to in vivo DNase I digestion in TNFSF6-expressing cells only, including upon T cell activation. Hypersensitivity to micrococcal nuclease digestion and to specific restriction enzyme digestion suggested the precise positioning of two nucleosomes across the transcription start site and minimal promoter region, likely interfering with TNFSF6 active transcription in T lymphocytes. Indeed, HSS1 hypersensitivity to nuclease digestion strictly correlated with TNFSF6 transcription, including in primary and leukemia T cells. HSS1 chromatin remodeling preceded detectable TNFSF6 mRNA accumulation and was blocked by cycloheximide that also prevented TNFSF6 transcription. However, DNA methylation levels of the TNFSF6 HSS1 region did not correlate with transcriptional activation. Induction of global protein acetylation by treatment with histone deacetylase inhibitors was not accompanied by HSS1 chromatin remodeling and/or TNFSF6 transcription. We conclude that chromatin remodeling is a primary event in the activation of TNFSF6 expression in primary and leukemia T cells and that mechanisms independent of protein deacetylation and of DNA methylation of the TNFSF6 promoter region are involved in the repression of TNFSF6 gene expression.
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PMID:Active transcription of the human FASL/CD95L/TNFSF6 promoter region in T lymphocytes involves chromatin remodeling: role of DNA methylation and protein acetylation suggest distinct mechanisms of transcriptional repression. 1659 63

NF-kappaB family members play a pivotal role in many cellular and organismal functions, including the cell cycle. As an activator of cyclin D1 and p21(Waf1) genes, NF-kappaB has been regarded as a critical modulator of cell cycle. To study the involvement of NF-kappaB in G(1)/S phase regulation, the levels of selected transcriptional regulators were monitored following overexpression of NF-kappaB or its physiological induction by tumor necrosis factor-alpha. Cyclin E gene was identified as a major transcriptional target of NF-kappaB. Recruitment of NF-kappaB to the cyclin E promoter was correlated with the transrepression of cyclin E gene. Ligation-mediated PCR and micrococcal nuclease-Southern assays suggested the nucleosomal nature of this region while chromatin immunoprecipitation analysis confirmed the exchange of cofactors following tumor necrosis factor-alpha treatment or release from serum starvation. There was a progressive reduction in cyclin E transcription along with the accumulation of catalytically inactive cyclin E-cdk2 complexes and arrest of cells in G(1)/S-phase. Thus, our study clearly establishes NF-kappaB as a negative regulator of cell cycle through transcriptional repression of cyclin E.
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PMID:p65 Negatively regulates transcription of the cyclin E gene. 2038 64