Participation of CRISP proteins in gamete interaction and their potential use for male fertility regulation

COHEN DJ; MALDERA JA; WEIGEL MUÑOZ M; ERNESTO JI; GOLDEWEIC NM; CUASNICÚ PS

Barcelona, España

Congreso; 9th International Congress of Andrology; 2009

International Society of Andrology

Mammalian fertilization is a complex multi-step process mediated by different molecules present on both gametes. Epididymal protein CRISP1, a member of the Cysteine-RIch Secretory Protein (CRISP) family, was identified by our laboratory and postulated to participate in gamete fusion by binding to egg-complementary sites. Structure-function studies using recombinant fragments of CRISP1 as well as synthetic peptides revealed that its egg-binding ability resides in a 12 amino acid region corresponding to an evolutionary conserved motif of the CRISP family, named Signature 2 (S2). Further experiments analyzing both the ability of other CRISP proteins to bind to the rat egg and the amino acid sequence of their S2 regions showed that the amino acid sequence of the S2 is needed for CRISP1 to interact with the egg. In addition to this, recent results revealed that CRISP1 would also be involved in the previous step of sperm binding to the zona pellucida, identifying a novel role for this protein in fertilization. The generation of CRISP1 “knock out” animals showed that, despite a normal animal fertility, CRISP1-defficient sperm present an impaired ability to fertilize both zona-intact and zona-free eggs confirming the proposed roles of the protein in gamete interaction. The finding that immunization of rats with native or recombinant CRISP1 raises specific antibodies which inhibits not only sperm fertilizing ability but also animal fertility, supports CRISP1 as a good epididymal contraceptive target. Evidence indicated that human CRISP1 (hCRISP1), as its rodent counterpart, also participates in both gamete fusion and sperm-ZP binding. In view of the role of hCRISP1 in fertilization, immunization studies were carried out in male and female non-human primates. Results showed that hCRISP1 is immunogenic and that the produced antibodies specifically recognize the endogenous monkey protein, enter the male reproductive tract and interact with sperm. Altogether, the results obtained increase our understanding on the molecular mechanisms of gamete interaction and support the potential use of CRISP family members for the development of new and safer fertility regulating methods.