Regulation of p16CDKN2 expression and its implications for cell immortalization and senescence.

Regulation of p16CDKN2 expression and its implications for cell immortalization and senescence. E Hara , R Smith , D Parry , H Tahara , S Stone and G Peters Imperial Cancer Research Fund Laboratories, London, United Kingdom. ABSTRACT p16CDKN2 specifically binds to and inhibits the cyclin-dependent kinases CDK4 and CDK6, which function as regulators of cell cycle progression in G1 by contributing to the phosphorylation of the retinoblastoma protein (pRB). Human cell lines lacking functional pRB contain high levels of p16 RNA and protein, suggesting a negative feedback loop by which pRB might regulate p16 expression in late G1. By a combination of nuclear run-on assays and promoter analyses in human fibroblasts expressing a temperature-sensitive simian virus 40 T antigen, we show that p16 transcription is affected by the status of pRB and define a region in the p16 promoter that is required for this response. However, the effect is not sufficient to account for the differences in p16 RNA levels between pRB-positive and -negative cells. Moreover, p16 RNA is extremely stable, and the levels do not change appreciably during the cell cycle. Primary human fibroblasts express very low levels of p16, but the RNA and protein accumulate in late-passage, senescent cells. The apparent overexpression of p16 in pRB-negative cell lines is therefore caused by at least two factors: loss of repression by pRB and an increase in the number of population doublings. CiteULike Connotea Delicious Digg Facebook Google+ Mendeley Reddit StumbleUpon Twitter What's this? « Previous | Next Article » Table of Contents This Article Mol. Cell. Biol. March 1996 vol. 16 no. 3 859-867 » Abstract PDF Services Email this article to a colleague Similar articles in ASM journals Alert me when this article is cited Alert me if a correction is posted Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of MCB Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Load citing article information Citing articles via Web of Science Citing articles via Google Scholar Google Scholar Articles by Hara, E. Articles by Peters, G. Search for related content PubMed PubMed citation Articles by Hara, E. Articles by Peters, G. Related Content Load related web page information Social Bookmarking CiteULike Connotea Delicious Digg Facebook Google+ Mendeley Reddit StumbleUpon Twitter What's this? current issue January 2012, volume 32, issue 1 Spotlights in the Current Issue Architecture of the Yeast RNA Polymerase II Open Complex State and Regulation by TFIIF GATA-1 Establishes Cell-Type-Specific Autophagy as a Developmental Program Prickle Phosphorylation Regulates Its Localization and β-Catenin-Independent Wnt Signaling Alert me to new issues of MCB About MCB Subscribers Authors Reviewers Advertisers Inquiries from the Press Permissions & Commercial Reprints ASM Journals Public Access Policy MCB RSS Feeds 1752 N Street N.W. • Washington DC 20036 202.737.3600 • 202.942.9355 fax • [email protected] Print ISSN: 0270-7306 Online ISSN: 1098-5549 Copyright © 2011 by the American Society for Microbiology. For an alternate route to MCB .asm.org, visit: http://intl- MCB .asm.org | More Info»