Regulation of expression by promoters versus internal ribosome entry site in the 5′-untranslated sequence of the human cyclin-dependent kinase inhibitor p27kip1

Zhaoqian Liu, Zizheng Dong, Baoguang Han, Youyun Yang, Yang Liu, Jian Ting Zhang

Research output: Contribution to journalArticle

37 Scopus citations

Abstract

p27kip1 regulates cell proliferation by binding to and inhibiting the activity of cyclin-dependent kinases and its expression oscillates with cell cycle. Recently, it has been suggested from studies using the traditional dicistronic DNA assay that the expression of p27kip1 is regulated by internal ribosome entry site (IRES)-mediated translation initiation, and several RNA-binding protein factors were thought to play some role in this regulation. Considering the inevitable drawbacks of the dicistronic DNA assay, which could mislead a promoter activity or alternative splicing to IRES as previously demonstrated, we decided to reanalyze the 5′-untranslated region (5′-UTR) sequence of p27kip1 and test whether it contains an IRES element or a promoter using more stringent methods, such as dicistronic RNA and promoterless dicistronic and monocistronic DNA assays. We found that the 5′-UTR sequence of human p27kip1 does not have any significant IRES activity. The previously observed IRES activities are likely generated from the promoter activities present in the 5′-UTR sequences of p27kip1. The findings in this study indicate that transcriptional regulation likely plays an important role in p27kip1 expression, and the mechanism of regulation of p27 expression by RNA-binding factors needs to be re-examined. The findings in this study also further enforce the importance that more stringent studies, such as promoterless dicistronic and monocistronic DNA and dicistronic RNA tests, are required to safeguard any future claims of cellular IRES.

Original languageEnglish (US)
Pages (from-to)3763-3771
Number of pages9
JournalNucleic acids research
Volume33
Issue number12
DOIs
StatePublished - Oct 17 2005

ASJC Scopus subject areas

  • Genetics

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