Involvement of Inhibitory Nuclear Factor-B (NFB)- Independent NFB Activation in the Gonadotropic Regulation of X-Linked Inhibitor of Apoptosis Expression during Ovarian Follicular Development

Increased X-linked inhibitor of apoptosis (XIAP) expression and suppressed follicular apoptosis are important determi-nants in the regulation of follicular development by FSH. The objective of the present study was to examine the role and regulation of nuclear factor-B (NFB) in the gonadotropic control of granulosa cell XIAP expression and follicular growth in vitro. FSH (100 ng/ml) increased rat granulosa cell XIAP mRNA abundance and protein content. The gonadotro-pin also induced granulosa cell p65 subunit-containing NFB translocation from cytoplasm to nucleus and increased NFB-DNA binding activity. Supershift EMSA indicated the FSH-activated NFB contained p65 and p50 subunits. Unlike TNF, FSH failed to elicit a significant change in granulosa cell phos-pho- and total-inhibitory NFB (IB) IB contents in vitro and dominant-negative IB expression was ineffective in blockin