The incidence of infertility due to both male and female factors continues to rise despite many advances in reproductive technologies. Some abnormalities in human gamete interaction have been shown to be due to defects in the sperm while others have been shown to be ZP defects. Our lack of understanding of molecular mechanisms involved in the interaction of human sperm with the ZP in fertile as compared to infertile females and males has been limited due to the unavailability of human oocytes and ethical restraints for experimental studies. Recent advances using in vitro fertilization technology which include intracellular sperm injection (ICSI) directly into the egg cytosol have been shown to be effective in many cases, although there are increasing ethical and clinical concerns as to the universal use of this technology. It is becoming increasingly apparent that improved clinical assays are necessary for evaluating sperm- ZP interaction in order to assess the optimal procedures for successful fertilization and pregnancy. In view of recent advances in molecular biology, the genes encoding the three major human ZP proteins have been identified and cDNAs are available to begin to better evaluate the molecular basis of sperm-ZP interaction. Because the ZP proteins of different mammalian species have been shown to have distinct roles in the fertilization process, it is apparent that the human ZP proteins must be utilized to evaluate human sperm- ZP interaction. Specifically, it is proposed to (1) express and characterize the three human ZP proteins using prokaryotic and eukaryotic expression systems that differentially glycosylate glycoproteins; (2) identify the functions of these expressed ZP proteins in sperm binding and initiation of the acrosome reaction and dissect the functional domains of the ZP proteins involved: and (3) use sperm from infertile males to determine if sperm dysfunction is due to molecular abnormalities involved in sperm/ZP interaction and develop clinical assays to evaluate infertile males. (4) determine if some infertile women have defects in ZP proteins that can be identified using single strand conformational polymorphism. These studies should also allow us to define molecules involved in these interactions which will aid in the treatment of infertility as well as provide information critical for the development of improved contraceptive methods.
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