Regulation of FSH Gene Expression and Release in Cultured Rat Anterior Pituitary Cells / 대한내분비학회지

ABSTRACT

BACKGROUND: FSH is a heterodimeric glycoprotein and is composed of alpha and beta subunits. alpha subunit is common to FSH and LH, while an unique beta subunit determines the biological specificity of each hormone. The synthesis of beta subunit is the primary rate-limiting step in the synthesis of each hormone. Although FSH plays a pivotal role in folliculogenesis and ovulation, very little studies have been performed on the regulation of FSH beta gene expression. Therefore, the present study attempted to examine the effect of GnRH or activin on the expression of FSH beta mRNA as well as FSH release and signaling pathway involved in their actions. METHODS: The primary cultures of rat anterior pituitary were used for this study. To determine FSH beta mRNA levels, northern blotting method was used. The concentration of FSH in the culture medium was evaluated by using a specific radioimmunoassay for rat FSH. RESULTS: PMA, an activator of PKC, increased FSH beta mRNA levels and FSH release, whereas forskolin, an activator of adenylate cyclase, showed no effect. The application of GnRH augmented FSH release, but not FSH beta mRNA levels. However, the administration of activin increased FSH beta mRNA levels as well as FSH release. Staurosporine, an inhibitor of PKC, suppressed activin-induced increment of FSH beta mRNA levels and FSH release. CONCLUSION: The present study demonstrated that activin rather than GnRH is a major regulator for FSH beta mRNA expression, and suggest that PKC-dependent pathway is also involved in the action of activin on the expression of FSH beta mRNA and FSH release.