HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 70/1/76    most recent biolreprod.103.020107v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal My Folders Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Yamada, K. Articles by Miyamoto, K. Search for Related Content PubMed PubMed Citation Articles by Yamada, K. Articles by Miyamoto, K. Agricola Articles by Yamada, K. Articles by Miyamoto, K.

Gene Expression of Basic Helix-Loop-Helix Transcription Factor, SHARP-2, Is Regulated by Gonadotropins in the Rat Ovary and MA-10 Cells¹

Department of Biochemistry,³ Fukui Medical University, Shimoaizuki, Matsuoka, Fukui 910-1193, Japan CREST,⁴ Japan Science and Technology Corporation, Kawaguchi, Saitama 332-0012, Japan

Basic helix-loop-helix (bHLH) proteins regulate transcription from the E box sequence (5'-CANNTG-3') located in the regulatory region of most gene promoters. The rat enhancer of split- and hairy-related protein 2 (SHARP-2) is a member of the bHLH protein family. To analyze the possible role of SHARP-2 in the rat ovary, the regulation of the expression of the SHARP-2 gene was examined, and the SHARP-2 protein was characterized. Northern blot analysis revealed that the level of SHARP-2 mRNA abruptly and temporarily increases as the result of the action of LH, i.e., eCG or hCG treatment alone or hCG after eCG treatment, in the rat ovary, as indicated by the treatment of primary cultured rat granulosa cells with hCG after FSH treatment or of mouse Leydig MA-10 cells with hCG or 8-bromoadenosine 3',5'-cyclic monophosphate. An in situ hybridization analysis showed that eCG treatment increases the level of the SHARP-2 transcript in theca interna cells and that hCG treatment, after the administration of eCG, increases the level of the SHARP-2 transcript in granulosa cells. Furthermore, transfection experiments with green fluorescence protein (GFP) expression vectors into primary cultured granulosa cells and MA-10 cells revealed that the entire coding sequence of SHARP-2 fused to the GFP is localized in the nucleus. The transcriptional activity of SHARP-2 also was examined using transient DNA transfection experiments. When an expression vector encoding the full length of SHARP-2 was cotransfected with thymidine kinase promoter-luciferase reporter plasmids, with or without E box sequences, into MA-10 cells, the luciferase activity was decreased in an E box-dependent manner. We conclude that the level of SHARP-2 mRNA is regulated by gonadotropins and that SHARP-2 functions as a transcriptional repressor localized in the nucleus.

¹ This study was supported by grants from the Ministry of Education, Science and Culture of Japan and CREST of Japan Science and Technology Corporation.

² Correspondence: Kazuya Yamada, Department of Biochemistry, Fukui Medical University, Matsuoka, Fukui 910-1193, Japan. FAX: 81 776 61 8102; kazuya{at}fmsrsa.fukui-med.ac.jp

This article has been cited by other articles:

				B. N. Karman and S. A. Tischkau Circadian Clock Gene Expression in the Ovary: Effects of Luteinizing Hormone Biol Reprod, October 1, 2006; 75(4): 624 - 632. [Abstract] [Full Text] [PDF]

				M. J Boden and D. J Kennaway Circadian rhythms and reproduction. Reproduction, September 1, 2006; 132(3): 379 - 392. [Abstract] [Full Text] [PDF]

				D. J. Kennaway The role of circadian rhythmicity in reproduction Hum. Reprod. Update, January 1, 2005; 11(1): 91 - 101. [Abstract] [Full Text] [PDF]