Id3 is a novel regulator of p27kip1 mRNA in early G1 phase and is required for cell-cycle progression

• Published in: Oncogene Vol. 26; no. 39; pp. 5772 - 5783
• Main Authors: CHASSOT, A.-A, TURCHI, L, VIROLLE, T, FITSIALOS, G, BATOZ, M, DECKERT, M, DULIC, V, MENEGUZZI, G, BUSCA, R, PONZIO, G
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 23-08-2007; Nature Publishing Group; Nature Publishing Group [1987-....]
• Subjects: Animals; Biochemistry; Biological and medical sciences; Cell cycle; Cell cycle, cell proliferation; Cell physiology; Cell proliferation; Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes; Cells, Cultured; Chromatin; Chromatin Immunoprecipitation; Cyclin A; Cyclin-dependent kinase inhibitor p27; Cyclin-Dependent Kinase Inhibitor p27 - genetics; Degradation; Dermis - injuries; Dermis - metabolism; Embryo, Mammalian - cytology; Embryo, Mammalian - metabolism; Fibroblasts; Fibroblasts - cytology; Fibroblasts - metabolism; Fundamental and applied biological sciences. Psychology; G1 phase; G1 Phase - physiology; Gene Expression Regulation; Gene silencing; Genetic aspects; Genetic transcription; Genetics; Humans; Immunoblotting; Immunoprecipitation; Inhibitor drugs; Inhibitor of Differentiation Proteins - physiology; Kinases; Life Sciences; Luciferases; Messenger RNA; Mice; Molecular and cellular biology; Neoplasm Proteins - physiology; NIH 3T3 Cells; Oncology; Phosphorylation; Physiological aspects; Polymerase chain reaction; Post-translation; Proteins; Reporter gene; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Small Interfering - pharmacology; S phase; S Phase - physiology; siRNA; Transcription, Genetic; Transfection; Wound Healing - physiology; Wounding; France; wound healing; Enzyme; cell-cycle; Esterases; p27mRNA; Carcinogenesis; Wound; Cyclin dependent kinase inhibitor; Iduronate-2-sulfatase; G1 Phase; Messenger RNA; Cell cycle; Hydrolases; Early; Ids; Sulfuric ester hydrolases; Cicatrization; Tumor suppressor gene
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/sj.onc.1210386

P27kip is a key inhibitory protein of the cell-cycle progression, which is rapidly downregulated in early G1 phase by a post-translational mechanism involving the proteosomal degradation. In this study, using a wounding model that induces cell-cycle entry of human dermal fibroblasts, we demonstrate that p27mRNA is downregulated when cells progress into the G1 phase, and then it returns to its basal level when cells approach the S phase. By using a quantitative polymerase chain reaction screening we identified inhibitors of differentiation (Id3), a bHLH transcriptional repressor, as a candidate mediator accounting for p27 mRNA decrease. Id3 silencing, using an small interfering RNA approach, reversed the injury mediated p27 downregulation demonstrating that Id3 is involved in the transcriptional repression of p27. Reporter gene experiments and a chromatin immunoprecipitation assay showed that Id3 likely exerts its repressive action through ELK1 inhibition. By inhibiting early p27 downregulation, Id3 depletion blocked (i) the G1-phase progression as assessed by the inhibition of pRb phosphorylation and p130 degradation and (ii) the G1/S transition as observed by the inhibition of cyclin A induction, demonstrating that p27 mRNA decrease is required for cell proliferation. Apart from its effect on the early p27 diminution, Id3 appears also involved in the control of the steady-state level of p27 at the G1/S boundary. In conclusion, this study identifies a novel mechanism of p27 regulation which besides p27 protein degradation also implicates a transcriptional mechanism mediated by Id3.