Follicle-stimulating hormone (FSH) increases FSH receptor messenger ribonucleic acid while decreasing FSH binding in cultured porcine granulosa cells.

Abstract

The goal of the present studies was to compare direct effects of porcine FSH (pFSH) on [125I]pFSH-binding sites with effects of pFSH on FSH receptor mRNA in cultured porcine granulosa cells. Cells from immature follicles were cultured on laminin-coated plates in serum-free medium for up to 6 days in the absence or presence of pFSH (1-100 ng/ml) or cholera toxin (0.04-400 ng/ml), which activates adenylyl cyclase independently of the FSH receptor. RRA indicated that [125I] pFSH binding to cells cultured without stimulator increased more than 10-fold with time in culture. Addition of pFSH to cultures resulted in a dose-dependent decrease in binding, assessed after removal of bound pFSH. Equilibrium saturation binding analysis indicated that pFSH (10 ng/ml) caused a 39% decrease in binding sites in cells cultured for 6 days. At the same time, pFSH increased progesterone production 9.5-fold. Cholera toxin (4 ng/ml) increased [125I]pFSH binding 110% and progesterone production 8.9-fold. Northern hybridization analysis of cultured granulosa cell mRNA using a porcine FSH receptor cDNA revealed three transcripts for the FSH receptor [2.2, 3.5, and 4.2 kilobases (kb)], with the major transcript being 4.2 kb in length. Addition of either pFSH (10 ng/ml) or cholera toxin (10 ng/ml) to cultures of granulosa cells increased the intensity of pFSH receptor transcripts compared with control values, with the 4.2-kb message remaining predominant. Hybridization with a porcine LH receptor cDNA revealed different transcripts (2.4, 4.0, 4.7, 7.0, and 11.0 kb), with the major transcript being 4.7 kb in length. Addition of either pFSH or cholera toxin to the cultures increased the intensity of all LH receptor transcripts; however, cholera toxin was more effective than pFSH. pFSH and cholera toxin increased the intensity of each species to different extents, although the 4.7-kb transcript remained predominant. These results indicate that exposure to FSH in culture results in down-regulation of the FSH receptor. Down-regulation is accompanied by increased FSH receptor mRNA levels, suggesting that FSH enhances FSH receptor synthesis.

Transcriptional regulation of the FSH receptor: New perspectives

“…Once in circulation, hormonal activity is directed through specific cell surface receptors, whose expression ultimately determines the site of action of these hormones. In the case of FSH, its receptor is expressed only in a subpopulation of gonadal somatic cells, Sertoli cells of the testis and granulosa cells of the ovary (Camp et al, 1991;Heckert and Griswold, 1991;Kliesch et al, 1992;Bockers et al, 1994;Houde et al, 1994;Sites et al, 1994;Dankbar et al, 1995;Rannikki et al, 1995;Tisdall et al, 1995;Xu et al, 1995;Yuan et al, 1996;Oktay et al, 1997;Yamamura et al, 2001;Mattiske et al, 2002;Bluhm et al, 2004;Kwok et al, 2005). Therefore, as the basis for directing FSH biological action to Sertoli and granulosa cells, the mechanisms regulating expression of Fshr are key determinants of endocrine control of gamete production and fertility.…”

Developmental Regulation of Follicle-Stimulating Hormone Receptor Messenger RNA Expression in the Baboon Fetal Ovary1

“…Female mice with targeted disruption of the gene for FSH␤ [5] or FSHR [6] and women homozygous for a point mutation in FSHR [7,8] do not exhibit normal reproductive cyclicity and are infertile. In the adult ovary, FSHR is expressed in granulosa cells [9][10][11] and oocytes [12] of immature [13] and more advanced [14] follicles. The gene for FSHR apparently is not highly regulated [14] but once expressed is maintained by factors active in enhancing follicle maturation, e.g., FSH and estrogen.…”

Regulation of Follicle-Stimulating Hormone Receptor

“…The second phase starts about 6 h after hormone addition and is characterized by an increase in FSH receptor mRNA levels. Using MA-10 Leydig tumor cells, it appeared that cAMP transiently increased the levels of luteinizing hormone/human chorionic gonadotrpin recep tor mRNA during short incubations, but decreased them during long incubations [ 14]. A down-regulatory effect of FSH and dbcAMP on FSH receptor mRNA was also observed in cultured Sertoli cells isolated from 21-day-old rats [15].…”