When an egg is released from a follicle in the ovary, the tissue that is left behind forms the corpus luteum and secretes hormones that are essential to sustain the ensuing pregnancy. Inadequate production of the steroid hormone progesterone from the corpus luteum is associated with pregnancy loss in cattle, sheep and horses.
In humans, this association is still unclear but further understanding how the corpus luteum develops and produces progesterone could lead to new fertility treatments.
In a study published in The Journal of Clinical Endocrinology & Metabolism a team led by Dr Xavier Donadeu at The Roslin Institute examined the effects of small non-coding RNA molecules (microRNAs) on the survival and production of progesterone by corpus luteum cells from patients undergoing assisted conception.
Previous studies by the authors have implicated microRNAs in the maturation of ovarian follicles in several farmed animal species. Here, they collected ovarian tissue from cattle to identify microRNAs that are upregulated as the corpus luteum develops. They found distinct increases in the levels of miR-96 and miR-132 in luteal tissue relative to follicular tissue.
These changes were mirrored in human luteal cells. Moreover, downregulating miR-96 with a specific inhibitor decreased the production of progesterone and triggered human luteal cell death. Further analyses revealed that the effects of miR-96 are mediated by the transcription factor FOXO1 shedding new light on potential targets for fertility treatments.
“This study highlights the validity of cattle as a model to study human ovarian physiology and fertility. Our comparative approach provides new insight into reproductive mechanisms in humans”.
Dr Xavier Donadeu, Group Leader, The Roslin Institute