title: Cell cycle regulation in H(2)O(2)-induced premature senescence of human diploid fibroblasts and regulatory control exerted by the papilloma virus E6 and E7 proteins.
abstract: Many biomarkers of replicative senescence appear in stress-induced premature senescence (SIPS) of human diploid fibroblasts (HDFs). The mRNA level of key cell cycle regulators was studied in H(2)O(2)-induced premature senescence of HDFs expressing or not the papillomavirus E6 and E7 proteins, which enhanced, respectively, the proteolysis of p53 and Rb. The CdKI's p21(waf-1) and p16(Ink-4a) were found overexpressed in H(2)O(2)-induced premature senescence, while p19(Ink-4d)and p27(Kip-1) were repressed. The results obtained in E6 HDFs suggest that p21(waf-1) and p16(Ink-4a) overexpressions are p53-independent, while p27(Kip-1) and p19(Ink-4d) down-regulations are p53-dependent.E6 regulated Rb, p130, p53 and p16(Ink-4a) mRNA level in non-stressing conditions, and regulated p130, p107, p53, p19(Ink-4d), p27(Kip-1) mRNA level in SIPS. SIPS modified the E6-mediated regulatory control on p107, p16(Ink-4a), p19(Ink-4d) and p27(Kip-1) mRNA level, when compared to normal conditions.E7 regulated the mRNA level of all the genes studied, in all conditions, suggesting that the Rb family or other E7-interacting proteins might modify the expression of these genes. SIPS modified strongly the E7-mediated regulatory control on p107, p16(Ink-4a), p19(Ink-4d), p27(Kip-1), p21(Waf-1) and Rb mRNA level, when compared to normal conditions. Further work is ongoing to test whether this E7-mediated regulatory control takes place through interactions with Rb or other E7-interacting proteins.
authors.affiliation: University of Namur (FUNDP), Unit of Cellular Biochemistry & Biology, 61, Rue de Bruxelles, B-5000, Namur, Belgium.
authors.forename: C
authors.initials: C
authors.lastname: Frippiat
authors.forename: Q M
authors.initials: QM
authors.lastname: Chen
authors.forename: J
authors.initials: J
authors.lastname: Remacle
authors.forename: O
authors.initials: O
authors.lastname: Toussaint
mesh_terms: D002453:Cell Cycle; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000235:genetics; D016161:Genes, Retinoblastoma; D016158:Genes, p53; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008869:Microtubule-Associated Proteins / Q000235:genetics; D009856:Oncogene Proteins, Viral / Q000502:physiology*; D050725:Papillomavirus E7 Proteins; D012333:RNA, Messenger / Q000032:analysis; D012097:Repressor Proteins; D025521:Tumor Suppressor Proteins
chemical_list: C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; C068651:E6 protein, Human papillomavirus type 16; D008869:Microtubule-Associated Proteins; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; D025521:Tumor Suppressor Proteins; C059731:oncogene protein E7, Human papillomavirus type 16; D050760:Cyclin-Dependent Kinase Inhibitor p27; D006861:Hydrogen Peroxide