Ovarian transcriptomes as a tool for a global approach of genes modulated by gonadotropic hormones in human ovarian granulosa cells

Follicle-stimulating hormone (FSH) is a key stimulant for the development of the ovarian follicle, while luteinizing hormone (LH) plays a major role in triggering ovulation and luteinization. Both FSH and LH are glycoprotein hormones that share the same alpha subunit but bind to specific seven transmembrane-domain G coupled receptors located on the cell membrane of the granulosa cells, which comprise the main somatic population of the ovarian follicle. These hormone-receptor complexes may trigger different signaling cascades, but the entire repertoire of genes modulated by these hormones is far from being understood, in particular on the transcriptional level. The development of DNA microarrays technique, using the entire genome profile of some mammalian species, allows a global approach and screening of multiple signal transduction pathways. This method opened new insights into the cellular and molecular events that control ovulation and desensitization of the corpus luteum to hyperstimulation by gonadotropic hormones. In addition, this technique permitted the discovery of novel members of the EGF family, such as epiregulin and amphiregulin, that were found to be expressed in the gonadotropin-stimulated cells and were discovered to play a crucial role in the mechanism of ovulation. However, because of the pitfalls in interpreting the data other approaches, for example, Northern blots and RT-PCR must be conducted in parallel to verify the validity of the data.