| Popis: |
Cystic ovarian disease (COD) is a major contributor to infertility in cattle, with 30% of cows developing ovarian cysts during a given lactation and becoming anovulatory. The cause of COD has remained elusive and is thought to be multifactorial, with angiogenic and genetic contributions proposed. There is an increasing body of work suggesting that microRNAs (miRNAs) may be involved in a number of ovarian-based reproductive disorders. Changes in miRNA expression can affect a multitude of genes and may be important regulators of the dynamic processes involved in each ovarian cycle. We hypothesized that miRNAs are integral to the regulation of critical ovarian processes such as angiogenesis and follicular development and that altered miRNA expression contributes to the onset and progression of ovarian dysfunction and reproductive disorders. Eight miRNAs (miR-15a, -18a, -20a, 21, -29a, -126, -132, Let7a) known to target vascular endothelial growth factor (VEGF), thrombospondin-1 (TSP-1), and play a role in both angiogenesis and folliculogenesis, were selected for analysis. miRNA, mRNA, and protein expression were analyzed in large and cystic bovine follicles using qPCR, western blot, and immunohistochemistry. miR-29a was found to be upregulated in cystic follicles, whereas miR-132 expression was downregulated. VEGF expression increased in cystic follicles at both the transcript and protein level, while no significant differences in TSP-1 expression was observed. Our findings suggest that miR-29a and miR-132 may play an important role in maintaining the balance between VEGF and TSP-1 expression in the ovary, and if disrupted, could potentiate ovarian-based reproductive disorders such as PCOS and cystic ovarian disorder. |
