The role of microRNAs in regulation of bovine ovarian follicular development

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Ovarian follicular physiology, which involves complex and coordinated processes and the interactions of different cell types, is known to be dependent on tightly regulated expression and interaction of a multitude of genes. In the present study the involvement of microRNAs in the regulation of genes involved in ovarian follicular development will be investigated through a systematic characterization and functional analysis of miRNAs identified in our previous study. Initially, 24 candidate miRNAs will be investigated for their expression in the follicular theca, granulosa cells, cumulus-oocyte complexes from the leading and subordinated follicles at days 3,7 and 19, whichs correspond to the selection, dominance and preovulatory stages, respectively. Based on this result, the differential expression pattern of some selected predicted target mRNAs will be investigated and compared to the expression profile of related miRNAs to find out the regulatory network of miRNA-mRNA interactions involved in follicular development. Subsequently, a maximum of 7 candidate miRNAs will be analysed for their involvement in follicular growth using a whole preantral follicle culture in vitro. Moreover, the same candidates will functionally studied in in vitro cultured granulosa and theca cells. Further, in vivo functional studies will be conducted by injection of inhibitor or mimics of 5 selected miRNAs into the ovary followed by investigation of alteration in follicular development as well as changes on the expression of miRNAs, mRNAs and related proteins. The proposed study will uncover the miRNAs dependent regulation of ovarian follicle turnover in bovine and could be modified for diagnostic and interventional procedures in human assisted reproduction.