Epigenetic control of folliculogenesis and luteinization

Folliculogenesis and luteinization are characterized by irreversible and profound physiological and morphological transformation processes, which eventually culminate in the provision of fertilizable eggs and the conversion of the estrogen producing follicle into a progesterone producing corpus luteum. All these processes are preceded by complex alterations of the gene expression profiles in the somatic cell layers granulosa and theca. It has been well established that epigenetic mechanisms, such as DNA methylation, histone modification and local changes of the chromatin structure, are essentially involved in cell type-specific gene activation and silencing. This short review will mainly focus on epigenetic processes that are induced by the gonadotropins FSH and LH during late folliculogenesis and luteinization. Data will be presented demonstrating that histone modification and chromatin modulation, but also DNA methylation are involved in the changing gene expression profiles during folliculogenesis and luteinization. Hence, these epigenetic mechanisms have to be considered to understand the control of the female reproductive cycle and pregnancy as well as pathological aberrations.