Histone deacetylases and repression of the gonadotropin genes.

The roles of chromatin modifications in transcription have been studied extensively; however, there remains a dearth of information explaining how extracellular signals induce changes in chromatin at a specific gene locus. The gonadotropins provide an example of genes that undergo significant fluctuations in their expression, and are regulated by gonadotropin-releasing hormone (GnRH) through a membrane-bound receptor. GnRH displaces histone deacetylases (HDACs) from gonadotropin genes in immature mouse gonadotropes, and some of the pathways have been elucidated. This GnRH effect likely comprises a mechanism involved in altering reproductive potential and provides a model for studying the regulation of derepression. This paper reviews the role of HDACs in repression of the gonadotropin genes and the mechanisms through which GnRH overcomes their actions.