Regulation of ovarian function

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Canada's pork industry produced 27 million pigs and exported 3.1 billion dollars of product worldwide in 2013. Reproductive efficiency is one of the key profitability components of the pork industry, however, compared to the more commonly used rodent models, our knowledge of ovarian physiology in this agriculturally important species is limited. The long term goal of my research program is to improve our understanding of pig ovarian physiology and thereby develop strategies to enhance sow productivity.******Two major functions of the ovary are the generation of competent oocytes and the production of hormones. These processes require coordinated gene expression within ovarian cells to operate correctly. MicroRNAs (miRNAs) are small non-coding RNAs that interact with the 3' untranslated region (3'UTR) of their target transcripts to suppress expression. With each miRNA able to target multiple genes, miRNA are known as important regulators of diverse physiological processes. However, the science concerning miRNAs in the ovary is largely unexplored. The target genes of most ovarian miRNAs are currently unknown, as are the functions of these small RNAs. We have recently demonstrated that miR-378 regulates production of the hormone estradiol in pig ovarian granulosa cells. This microRNA also suppressed progesterone receptor expression, cumulus expansion and oocyte maturation. We plan to investigate the stage-dependent expression of specific miRNAs during ovarian follicle development to identify follicular-stage and cell-type patterns of miRNA expression. These results will allow us to test hypotheses about the functions of specific miRNAs using approaches established in our lab, including lentivirus-mediated over expression, apoptosis and proliferation assays, and ELISA, in granulosa cells. This work will then be expanded to observe the role of miRNA in oocyte maturation and embryo development. Finally, how miRNA regulation in ovarian follicle cells affects ovarian physiology and fertility will be confirmed in vivo. Understanding miRNA regulation of ovarian function may lead to strategies to enhance sow fertility. Since a single miRNA may have the potential to regulate the activity of an entire molecular pathway, these molecules may be linked with attractive genetic markers for selection towards or against desired reproductive traits in potential gilts for recruiting into breeding stock.*****************