Genomic portrait of ovarian follicle growth regulation in cattle.

The female reproductive cycle is characterized by cyclic patterns of growth of ovarian follicles destined to ovulate and the degeneration of those not chosen for ovulation. Apoptosis is the underlying mechanism of ovarian follicle degeneration during atresia. The fate of ovarian follicles is under the control of endocrine hormones (e.g. gonadotropins) and intra-ovarian regulators (e.g. growth factors and gonadal steroids), but the intra-cellular and molecular regulation of follicle fate (cellular proliferation or atresia) are still not fully understood. Studies using genomic tools which aim to determine the expression profiles of mRNAs and miRNAs in bovine dominant and subordinate ovarian follicles at different stages of the follicle wave have indicated that there are some novel molecular factors (e.g. FOXO1 and miR-183∼96∼182 cluster) associated with ovarian follicle development. Furthermore, bioinformatics tools have been used to identify the interactions between mRNAs and miRNAs leading to better understanding of ovarian follicle growth regulation in cattle. This review summarizes the recent findings about the complex intracellular communication networks involving miRNA, their target genes and signalling molecules which together may coordinate the fate of cattle ovarian follicles.