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PMID: 16326864 Published · epublish English Journal Article Research Support, Non-U.S. Gov't

CTCF binds the proximal exonic region of hTERT and inhibits its transcription.

Nucleic acids research ·Vol. 33 ·No. 21 ·2005-00-00 ·Pages 6850-60

Renaud S, Loukinov D, Bosman FT, Lobanenkov V, Benhattar J

Abstract

The expression of the catalytic subunit (hTERT) represents the limiting factor for telomerase activity. Previously, we detected a transcriptional repressor effect of the proximal exonic region (first two exons) of the hTERT gene. To better understand the mechanism involved and to identify a potential repressor, we further characterized this region. The addition of the hTERT proximal exonic region downstream of the hTERT minimal promoter strongly reduced promoter transcriptional activity in all cells tested (tumor, normal and immortalized). This exonic region also significantly inhibited the transcriptional activity of the CMV and CDKN2A promoters, regardless of the cell type. Therefore, the repressor effect of hTERT exonic region is neither cell nor promoter-dependent. However, the distance between the promoter and the exonic region can modulate this repressor effect, suggesting that nucleosome positioning plays a role in transcriptional repression. We showed by electrophoretic mobility shift assay that CCCTC-binding factor (CTCF) binds to the proximal exonic region of hTERT. Chromatin immunoprecipitaion assays confirmed the binding of CTCF to this region. CTCF is bound to hTERT in cells in which hTERT is not expressed, but not in telomerase-positive ones. Moreover, the transcriptional downregulation of CTCF by RNA interference derepressed hTERT gene expression in normal telomerase-negative cells. Our results suggest that CTCF participates in key cellular mechanisms underlying immortality by regulating hTERT gene expression.

MeSH Terms
Binding Sites CCCTC-Binding Factor Cell Line, Tumor Cells, Cultured DNA-Binding Proteins/biosynthesis,genetics,metabolism Exons Gene Silencing Humans Promoter Regions, Genetic Repressor Proteins/metabolism Telomerase/biosynthesis,genetics Transcription, Genetic
Chemicals
CCCTC-Binding Factor CTCF protein, human DNA-Binding Proteins Repressor Proteins Telomerase
Authors & Affiliations
5 authors, click to expand affiliations / ORCID
Renaud Stéphanie
Institute of Pathology, Centre Hospitalier Universitaire Vaudois, Bugnon 25, 1011 Lausanne, Switzerland.
Loukinov Dmitri
Bosman Fred T
Lobanenkov Victor
Benhattar Jean
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Article Info
Journal
Nucleic acids research
Abbr.
Nucleic Acids Res
ISSN
1362-4962
DOI
10.1093/nar/gki989
Published
2005-00-00
Epub
2005-00-02
Pages
6850-60
Language
English
Region
England
NLM ID
0411011
PMCID
PMC1301598
Subset
IM
External Links
PubMed source DOI: 10.1093/nar/gki989 PMC Full Text View journal details
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