Liver receptor homologue-1 regulates gonadotrope function

Abstract

Over the past decade, substantial advances have been made in our understanding of the transcription factors which regulate gene expression in gonadotropes. One of the most important of these factors, steroidogenic factor-1 (SF-1; NR5A1) is critical for gonadotropin and GnRH-receptor expression. Interestingly, a closely related nuclear hormone receptor, liver receptor homologue-1 (LRH-1; NR5A2) has recently been detected in the anterior pituitary gland; however, its functional significance in this tissue has not been investigated. For the experiments reported here, we hypothesized that LRH-1 plays a previously unrecognized role in gonadotrope physiology. Towards this end, we first demonstrate LRH-1 mRNA and protein expression in both primary pituitary cells and gonadotrope-derived cell lines. We next show that LRH-1 stimulates promoter activity of the GnRH-receptor and gonadotropin subunit genes. Within the LHbeta gene, this response appears to be mediated by DNA-binding and transactivation through previously characterized SF-1 cis-elements. To our knowledge, this is the first report demonstrating a functional role for LRH-1 in the gonadotrope population of the anterior pituitary gland.