Fellowship Misung Jo: Regulation and Function of MMP 19 in the Ovary

The preovulatory gonadotropin surge triggers a dramatic, yet orchestrated process that culminates in the rupture of ovulatory follicle wall at the apex and subsequent release of the oocyte-cumulus complex. Stimulation of proteolytic activity during the ovulatory process is believed to be prerequisite for the degradation of the follicular basement membrane and dissolution of the apical follicle wall tissue. A family of proteolytic enzymes, the matrix metalloproteinases (MMPs), and their endogenous inhibitors, the tissue inhibitors of metalloproteinase (TIMPs), have been shown to play crucial roles in the process of ovulation in several species. Recently, there is a report showing the expression ofmRNA for MMP-19, a novel member ofMMPs, in the mouse ovary after hCG injection to induce ovulation. However, nothing is known about the regulatory mechanisms ofMMP-19 gene expression and its function(s) in the ovary. In this proposal, we will test the hypotheses that the LHIFSH surge stimulates MMP-19 expression in periovulatorv follicles and MMP-19 is involved in the degradation of the follicular basement membrane at the time of ovulation. The immature PMSG/hCG primed female rat will serve as an animal model. Expression pattern ofMMP-19 mRNA as well as the intracellular signaling pathway(s) through which MMP-19 mRNA expression is regulated will be examined using Northern blot, in situ hybridization, RNase protection assay. We will further explore the functional aspect ofMMP-19 in the ovary by examining its proteolytic activity on type IV collagen and aggrecan utilizing peptide cleavage analysis, Western blot and silencing RNA. The results derived from the proposed experiments will lead to more detailed and thorough understanding of the events involved in the ovulatory process. As this process is fundamental for female fertility and has broad implications in developing fertility control methods for women, this knowledge will be useful for designing strategies to regulate fertility and develop more effective and/or efficient methods for contraception.