title: Transcriptional regulation of the cyclin-dependent kinase inhibitor 1A (p21) gene by NFI in proliferating human cells.
abstract: The cyclin-dependent kinase inhibitor 1A (CDKN1A), also known as p21 (WAF1/CIP1) modulates cell cycle, apoptosis, senescence and differentiation via specific protein-protein interactions with the cyclins, cyclin-dependent kinase (Cdk), and many others. Expression of the p21 gene is mainly regulated at the transcriptional level. By conducting both ligation-mediated PCR (LMPCR) and chromatin immunoprecipitation (ChIP) in vivo, we identified a functional target site for the transcription factor, nuclear factor I (NFI), in the basal promoter from the p21 gene. Transfection of recombinant constructs bearing mutations in the p21 NFI site demonstrated that NFI acts as a repressor of p21 gene expression in various types of cultured cells. Inhibition of NFI in human skin fibroblasts through RNAi considerably increased p21 promoter activity suggesting that NFI is a key repressor of p21 transcription. Over-expression of each of the four NFI isoforms in HCT116 cells established that each of them contribute to various extend to the repression of the p21 gene. Most of all, over-expression of NFI-B in doxorubicin, growth-arrested HCT116 increased the proportion of cells in the S-phase of the cell cycle whereas NFI-A and NFI-X reduced it, thereby establishing a role for NFI in the cell cycle dependent expression of p21.
authors.affiliation: Service of Genetics, Department of Pediatrics, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Ouellet
authors.forename: François
authors.initials: F
authors.lastname: Vigneault
authors.forename: Maryse
authors.initials: M
authors.lastname: Lessard
authors.forename: Steeve
authors.initials: S
authors.lastname: Leclerc
authors.forename: Régen
authors.initials: R
authors.lastname: Drouin
authors.forename: Sylvain L
authors.initials: SL
authors.lastname: Guérin
mesh_terms: D000818:Animals; D001665:Binding Sites; D002453:Cell Cycle / Q000235:genetics; D049109:Cell Proliferation; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics*; D018983:DNA Footprinting; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D051839:NFI Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D051381:Rats; D012097:Repressor Proteins / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C493956:CDKN1A protein, human; D016895:Culture Media, Serum-Free; D050759:Cyclin-Dependent Kinase Inhibitor p21; D051839:NFI Transcription Factors; D012097:Repressor Proteins