HEXIM1 is a promiscuous double-stranded RNA-binding protein and interacts with RNAs in addition to 7SK in cultured cells

Qintong Li; Jeffrey J Cooper; Gary H Altwerger; Michael D Feldkamp; Madeline A Shea; David H Price

doi:10.1093/nar/gkm150

Back

HEXIM1 is a promiscuous double-stranded RNA-binding protein and interacts with RNAs in addition to 7SK in cultured cells

Journal article

Open access

Peer reviewed

HEXIM1 is a promiscuous double-stranded RNA-binding protein and interacts with RNAs in addition to 7SK in cultured cells

Qintong Li, Jeffrey J Cooper, Gary H Altwerger, Michael D Feldkamp, Madeline A Shea and David H Price

Nucleic acids research, Vol.35(8), pp.2503-2512

04/2007

DOI: 10.1093/nar/gkm150

PMCID: PMC1885667

PMID: 17395637

Files and links (1)

url

https://doi.org/10.1093/nar/gkm150View

Published (Version of record) Open Access

Abstract

P-TEFb regulates eukaryotic gene expression at the level of transcription elongation, and is itself controlled by the reversible association of 7SK RNA and an RNA-binding protein HEXIM1 or HEXIM2. In an effort to determine the minimal region of 7SK needed to interact with HEXIM1 in vitro , we found that an oligo comprised of nucleotides 10–48 sufficed. A bid to further narrow down the minimal region of 7SK led to a surprising finding that HEXIM1 binds to double-stranded RNA in a sequence-independent manner. Both dsRNA and 7SK (10–48), but not dsDNA, competed efficiently with full-length 7SK for HEXIM1 binding in vitro . Upon binding dsRNA, a large conformational change was observed in HEXIM1 that allowed the recruitment and inhibition of P-TEFb. Both subcellular fractionation and immunofluorescence demonstrated that, while most HEXIM1 is found in the nucleus, a significant fraction is found in the cytoplasm. Immunoprecipitation experiments demonstrated that both nuclear and cytoplasmic HEXIM1 is associated with RNA. Interestingly, the one microRNA examined (mir-16) was found in HEXIM1 immunoprecipitates, while the small nuclear RNAs, U6 and U2, were not. Our study illuminates novel properties of HEXIM1 both in vitro and in vivo , and suggests that HEXIM1 may be involved in other nuclear and cytoplasmic processes besides controlling P-TEFb.

RNA

Details

Title: Subtitle: HEXIM1 is a promiscuous double-stranded RNA-binding protein and interacts with RNAs in addition to 7SK in cultured cells
Creators: Qintong Li - Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, USA
Jeffrey J Cooper - Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, USA
Gary H Altwerger - Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, USA
Michael D Feldkamp - Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, USA
Madeline A Shea - Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, USA
David H Price - Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, USA
Resource Type: Journal article
Publication Details: Nucleic acids research, Vol.35(8), pp.2503-2512
DOI: 10.1093/nar/gkm150
PMID: 17395637
PMCID: PMC1885667
NLM abbreviation: Nucleic Acids Res
ISSN: 0305-1048
eISSN: 1362-4962
Publisher: Oxford University Press
Language: English
Date published: 04/2007
Academic Unit: Molecular Physiology and Biophysics; Iowa Neuroscience Institute; Biochemistry and Molecular Biology
Record Identifier: 9984024556902771

Metrics

23 Record Views

43 Times Cited - Web of Science