Oviductal regulation of gamete interaction and reproductive function

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The mammalian oviduct occupies a unique position in the female reproductive tract where it provides the optimal microenvironment for many critical reproductive events to occur. This proposal examines the function of hamster oviduct-specific glycoprotein (HamOVGP1) during the early events of the reproductive process and builds on work accomplished during the tenure of my last NSERC-DG as well as preliminary results recently obtained. We have previously shown the ability of HamOVGP1 to enhance sperm capacitation, a prerequisite for acrosome reaction, by potentiating tyrosine phosphorylation of a subset of sperm proteins. In the present proposal, our first objective is to perform high throughput phosphoproteomic analysis to further characterize the rHamOVGP1-enhanced tyrosine phosphorylated sperm proteins and their functions. In our last NSERC-DG, we hypothesized that putative HamOVGP1-binding sites are present on the surface of hamster uterine epithelial cells. To test this hypothesis, we used both in situ and in vitro approaches to demonstrate the presence of HamOVGP1-binding sites on the cell surface of a population of uterine epithelial cells. To carry this work further, we have designed an experimental scheme to test the hypothesis that HamOVGP1-binding sites on the surface of uterine epithelial cells have anti-adhesive property acting as a barrier for implantation whereas the cells that lack surface HamOVGP1-binding sites act as the sites for implantation. Our second objective is to examine the role of HamOVGP1 in uterine receptivity. We have successfully established primary hamster uterine epithelial cell cultures. We will isolate and culture the two cell populations of uterine cells and then determine which cell population hamster embryos will adhere to. Recently my collaborator in Japan, Dr. Y. Araki, has established ovgp1-null hamsters. Our preliminary studies showed that ovgp1-/- female hamsters are infertile. Interestingly, one ovgp1-/-female hamster exhibited infertile phenotype and was found to exhibit a phenotype similar to ectopic pregnancy in humans, reinforcing our hypothesis that HamOVGP1 plays a role in uterine receptivity. Based on these premises, our third objective is to further characterize the phenotypes of the ovgp1-/- and ovgp1+/- hamsters using molecular, cellular and immunocytochemical approaches focusing on the role of HamOVGP1 in uterine receptivity. Using the recombinant HamOVGP1 that we successfully produced during the tenure of my last NSERC DG and the availability of ovgp1-null hamsters, it is now possible to unravel how HamOVGP1 regulates some of the key events that lead to successful fertilization and its role in early implantation. Results obtained from this study can be extrapolated for the development of improved insemination procedures for farm animals in the Canadian agriculture industry and IVF procedures involving rodents in research laboratories and involving humans in IVF fertility clinics.