Novel genes regulated by gonadotropins in granulosa cells: new perspectives on their physiological functions.

Follicular stimulating hormone (FSH) is a key hormone secreted from the pituitary, which controls the development of the follicle-enclosed oocytes in the mammalian ovary by interacting with specific receptors located exclusively on granulosa cells. Its biological activity involves stimulation of intercellular communication and upregulation of steroidogenesis, yet the entire spectrum of genes which are regulated by FSH are not fully characterized. We have established rat and human FSH responsive granulosa cell lines, which express FSH receptors at 20-times higher rates compared to primary cells. Since the lines are monoclonal, they are expected to have a homogeneous composition of RNA among the entire cell population, which increases the probability of yielding a distinct view of genes modulated by FSH eliminating the possibility of other cell types contamination. Using Affymetrix DNA microarrays to uncover novel FSH-regulated genes, we discovered genes not reported earlier to be regulated by FSH. These include genes coding for (1) proteases; (2) growth factors and cytokines; (3) proteins involved in intercellular communication and connection with the nervous system; (4) protein phosphatases and kinases; (5) anti oxidants and anti-toxicants; (6) G-coupled proteins. These findings can deepen our understanding in the mechanism of FSH action in stimulation of the development of the ovarian follicular cells, in the modulation of ovarian intracellular and intercellular communication and in the process of selection of the dominant follicle. When human granulosa cells, obtained from in vitro fertilization patients were exposed to either hLH- or hFSH stimulation and mRNAs of these cells were analyzed by DNA microarrays, novel genes, similar to those found modulated by FSH in FSH responsive cell lines, were discovered in the human primary cells. This suggests that the immortalized cell systems established in our laboratory could serve as a useful system expanding the spectrum of authentic genes modulated by gonadotropin stimulation in normal ovarian function and in ovarian malfunction.