The goal of the proposed research is to define the molecular and cellular events that occur within the primate periovulatory follicle that are critical for fertility. While the necessity of pituitary-derived luteinizing hormone (LH) for ovulation and development of the corpus luteum (CL) is well known, the specific cellular activities required for such processes to occur are poorly defined. Through the use of high-throughput genomic profiling methods, the P.I. and colleagues created extensive mRNA expression databases from primate follicles isolated prior to and following an ovulatory stimulus as well as in the developing CL. From the resultant transcriptome data, several pathways involved in coordinating LH action were identified. First, although progesterone (P) is known to be an important LH-induced regulator of ovulation and luteal development/function, our preliminary studies suggest unique roles for P action in primate ovulation and luteal development depend on its signaling through the nuclear P receptor (PGR) or related membrane associated P receptors (P receptor membrane component- 1 and -2; PGRMC1 and PGRMC2, respectively). Secondly, cortisol levels increase in the follicle after an ovulatory stimulus, which is associated with significantly increased expression of 11?-hydroxysteroid dehydrogenase-1 (HSD11B1) mRNA and reduced levels of HSD11B2 mRNA. HSD11B1 converts biologically inert cortisone to cortisol that can bind to and activate the glucocorticoid receptor, whereas HSD11B2 metabolizes cortisol to cortisone. Importantly, cortisol levels were significantly higher in rhesus monkey follicles that yielded oocytes capable of undergoing fertilization and embryonic development than in follicles whose oocytes remained unfertilized or failed to develop to an implantation stage embryo (i.e., a blastocyst). Lastly, the cytokine leukemia inhibitory factor (LIF) and its signaling pathway is induced following an ovulatory stimulus and blocking LIF action prevented ovulation in rhesus monkeys. While our findings to date support an important role for P, cortisol, and LIF in coordinating LH action in the primate follicle, the specific processes they regulate are not understood. Thus, studies are proposed in adult, female rhesus monkeys to test the hypotheses that:
(Aim 1) PGR and PGRMC1, -2 regulate distinct events critical for ovulation and luteal development, (Aim 2) HSD11B1 is critical for the local generation of cortisol, which acts through the glucocorticoid receptor present in the follicle to elicit the release of an oocyte competent for fertilization and embryonic development, and (Aim 3) LIF regulates the expression of a network of genes necessary for follicle rupture. The proposed studies will employ a controlled ovulation (COv) protocol that allows for the development, manipulation, and isolation of the naturally-selected rhesus macaque follicle from which a systematic genomic and cellular assessment of steroid (P, cortisol) and cytokine (LIF) control of ovulation and luteal development can be characterized. These experiments will provide important insight into the mechanisms controlling ovulation and the development of the CL, and hence fertility, in primates.
This application proposes research to understand how the mid menstrual cycle surge of pituitary- derived luteinizing hormone (LH) indirectly, via locally synthesized steroids (progesterone or cortisol) and cytokines (leukemia inhibitory factor), coordinates events necessary for primate ovulation and corpus luteum development.
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