Abstract: 456

CCAAT/ENHANCER BINDING PROTEIN (C/EBP) AND C/EBP MAY BE INVOLVED IN FSH DEPENDENT GENE EXPRESSION IN RAT SERTOLI CELLS.

SA Khan^{1 *}, A Brown¹ , D Nalbant¹ , SC Williams¹
Dept Cell Biol & Biochem, Texas Tech Univ Health Sci Ctr, Lubbock, TX ¹

Sertoli cell development and function is regulated by follicle stimulating hormone (FSH). FSH effects on Sertoli cells are exerted primarily by increased intracellular levels of cAMP.The effects of cAMP on gene expression are mediated by increased levels and activity of a family of cAMP response elements binding (CREB) proteins. Since several cAMP-responsive genes lack consensus CRE sequences, they are likely to be regulated by other cAMP-stimulated transcription factors such as the C/EBP family of proteins. In the current study we have investigated the expression of C/EBP family members and their regulation by FSH in immature rat Sertoli cells. Sertoli cells were isolated from 10 day old rats, cultured in serum-free medium and treated with FSH. Total RNA and proteins were then isolated for PCR amplification, Northern analysis, and Western blotting of C/EBP family members. Using RT-PCR we detected mRNA for C/EBP and C/EBP in untreated Sertoli cells which increased significantly after treatment with FSH. mRNAs for other family members (C/EBP and C/EBP) were not found in either untreated or FSH treated cells. Using Northern blots, we observed that C/EBP and C/EBP mRNA levels increased significantly after 4 h. treatment with FSH, which were significantly decreased after 24 h. The levels of C/EBP and C/EBP proteins determined by Western blotting also exhibited similar increases after FSH treatment. Increased levels of both proteins were also observed in cells treated with cAMP analogs, a phosphodiesterase inhibitor, or forskolin. These results suggest that FSH induces the expression of C/EBP and C/EBP in immature rat Sertoli cells in vitro, and that these effects are mediated by cAMP. These transcription factors may therefore be involved in FSH/cAMP dependent gene expression in Sertoli cells.

    This abstract is being presented on Tuesday, August 3 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.