Reproduction Abstracts

Little is known about the involvement of miRNAs in luteal development. Cattle provide a convenient model to study ovarian physiology in monovular species. Our previous microarray studies in bovine showed significant upregulation of miR-96 and miR-132 in luteal relative to follicular tissues. In the present study we used an in vitro model of forskolin-induced follicular granulosa cell luteinisation, transfection with specific locked nucleic acid inhibitors or mimics of miR-132 and miR-96 led, respectively, to abolished expression and a significant increase in the levels of these miRNAs (P<0.01) within 4 days. The induced changes in miRNA levels during luteinisation did not have any effect on the transcript levels of predicted mRNA targets including FOXO1and ADCY6. We then investigated the functional involvement of these miRNAs in cultured bovine luteal cells. Inhibition of miR-132 and miR-96 led to abolished expression of these miRNAs (P<0.01) within 2 days, loss of function of these miRNAs did not have a significant effect (P>0.1) on progesterone production by luteal cells. However, their effects on the expression of the putative target of miR-96 and miR-132, FOXO1, were determined. Inhibition of miR-132 led to an increase (P<0.05) in transcript but not protein levels of FOXO1. In contrast, inhibition of miR-96 resulted in increased protein but not transcript levels of FOXO1. Our results indicate a potential involvement of miR-96 and miR-132 in promoting luteal cell survival. To confirm this, we are currently investigating the effects of these two miRNAs on apoptotic genes and the response of luteal cells to different pro-apoptotic stimuli.