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© 2001 by The American Society for Biochemistry and Molecular Biology, Inc.
The UV-inducible RNA-binding Protein A18 (A18 hnRNP) Plays a Protective Role in the Genotoxic Stress Response*
From the Department of Biochemistry and Molecular Biology,
University of Maryland School of Medicine,
Baltimore, Maryland 21201-1503
We have previously shown that specific
RNA-binding proteins (RBP) are activated by genotoxic stress. The role
and function of these stress-activated RBP are, however, poorly
understood. The data presented here indicate that the RBP A18
heterogeneous ribonucleoprotein (hnRNP) is induced and translocated
from the nuclei to the cytoplasm after exposure to UV radiation. Using a new in vitro system we identified potential cellular
targets for A18 hnRNP. Forty-six mRNA transcripts were identified,
most of which are stress- or UV-responsive genes. Two important
stress-responsive transcripts, the replication protein A (RPA2) and
thioredoxin, were studied in more detail. Northwestern analyses
indicate that A18 hnRNP binds specifically to the 3'-untranslated
region of RPA2 transcript independently of its poly(A) tail, whereas
the poly(A) tail of thioredoxin mRNA reinforces binding.
Overexpression of A18 hnRNP increases the mRNAs stability and
consequently enhances translation in a dose-dependent
manner. Moreover, cell lines expressing reduced levels of A18 hnRNP are
more sensitive to UV radiation. These data suggest that A18 hnRNP plays
a protective role against genotoxic stresses by translocating to the
cytosol and stabilizing specific transcripts involved in cell survival.
* This work was supported by NIGMS, National Institutes of Health Grant RO1GM57827-01. (to F. C.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
To whom correspondence should be addressed: 108 N. Greene St., Rm.
330, Baltimore, MD 21201-1503. Tel.: 410-706-5105; Fax: 410-706-8297;
E-mail: fcarr001@umaryland.edu.
Copyright © 2001 by The American Society for Biochemistry and Molecular Biology, Inc. THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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Science Signaling. ISSN 1937-9145 (online), 1945-0877 (print). Pre-2008: Science's STKE. ISSN 1525-8882