Assembly of the Yin Yang 1 Transcription Factor into Messenger Ribonucleoprotein Particles Requires Direct RNA Binding Activity*
- Department of Anatomy and Cell Biology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
- 2 To whom correspondence should be addressed: Dept. of Anatomy and Cell Biology, College of Medicine, University of Saskatchewan, A308 Health Sciences Bldg., 107 Wiggins Rd., Saskatoon, Saskatchewan S7N 5E5, Canada. Tel.: 306-966-1460; E-mail: nick.ovsenek{at}usask.ca.
Abstract
The early stages of vertebrate development depend heavily on control of maternally transcribed mRNAs that are stored for long periods in complexes termed messenger ribonucleoprotein particles (mRNPs) and utilized selectively following maturation and fertilization. The transcription factor Yin Yang 1 (YY1) is associated with cytoplasmic mRNPs in vertebrate oocytes; however, the mechanism by which any of the mRNP proteins associate with mRNA in the oocyte is unknown. Here we demonstrate the mechanism by which YY1 associates with mRNPs depends on its direct RNA binding activity. High affinity binding for U-rich single-stranded RNA and A:U RNA duplexes was observed in the nanomolar range, similar to the affinity for the cognate double-stranded DNA-binding element. Similar RNA binding affinity was observed with endogenous YY1 isolated from native mRNP complexes. In vivo expression experiments reveal epitope-tagged YY1 assembled into high molecular mass mRNPs, and assembly was blocked by microinjection of high affinity RNA substrate competitor. These findings present the first clues to how mRNPs assemble during early development.
Footnotes
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↵ 3 The abbreviations used are: YY1, Yin Yang 1; mRNP, messenger ribonucleoprotein particle; EMSA, electrophoretic mobility shift assay; DTT, dithiothreitol; NTA, nitrilotriacetic acid; HA, hemagglutinin; PCNA, proliferating cell nuclear antigen.
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↵* This work was supported in part by a Natural Sciences and Engineering Research Council of Canada Discovery Grant (to N. O.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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The on-line version of this article (available at http://www.jbc.org) contains supplemental probe sequences.
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↵1 Supported by a University of Saskatchewan, College of Medicine Graduate Scholarship.
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- Received September 26, 2007.
- Revision received October 31, 2007.
