Originally published In Press as doi:10.1074/mcp.M800052-MCP200 on May 2, 2008.
Molecular & Cellular Proteomics 7:1517-1529, 2008.
© 2008 by The American Society for Biochemistry and Molecular Biology, Inc.
Research
A Proteomics Approach for Identification of Single Strand DNA-binding Proteins Involved in Transcriptional Regulation of Mouse µ Opioid Receptor Gene*
Hack Sun Choi ,
Kyu Young Song,
Cheol Kyu Hwang,
Chun Sung Kim ,
Ping-Yee Law,
Li-Na Wei and
Horace H. Loh
From the Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota 55455
The pharmacological actions of morphine and morphine-like drugs such as heroin are mediated primarily through the µ opioid receptor. Previously a single strand DNA element of the mouse µ opioid receptor gene (Oprm1) proximal promoter was found to be important for regulating Oprm1 in neuronal cells. To identify proteins binding to the single strand DNA element as potential regulators for Oprm1, affinity column chromatography with the single strand DNA element was performed using neuroblastoma NS20Y cells followed by two-dimensional gel electrophoresis and MALDI-TOF mass spectrometry. We identified five poly(C)-binding proteins: heterogeneous nuclear ribonucleoprotein (hnRNP) K, -complex proteins ( CP) CP1, CP2, CP2-KL, and CP3. Binding of these proteins to the single strand DNA element of Oprm1 was sequence-specific as confirmed by supershift assays. In cotransfection studies, hnRNP K, CP1, CP2, and CP2-KL activated the Oprm1 promoter activity, whereas CP3 acted as a repressor. Ectopic expression of hnRNP K, CP1, CP2, and CP2-KL also led to activation of the endogenous Oprm1 transcripts, and CP3 repressed endogenous Oprm1 transcripts. We demonstrate novel roles as transcriptional regulators in Oprm1 regulation for hnRNP K and CP binding to the single strand DNA element.
To whom correspondence should be addressed: Dept. of Pharmacology, University of Minnesota Medical School, 6-120 Jackson Hall, 321 Church St. S. E., Minneapolis, MN 55455. Tel.: 612-626-6539; Fax: 612-625-8408; E-mail: choix074{at}umn.edu

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Copyright © 2008 by the American Society for Biochemistry and Molecular Biology.
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