Behaviour of CRISP proteins during capacitation and their role in gamete interaction

CUASNICU PS; COHEN D.J; MALDERA JA; WEIGEL MUÑOZ M; ERNESTO JI; BATTISTONE A; VASEN G

Proceedings of the 11th International Symposium on Spermatology

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Año: 2011;

Rat epididymal protein CRISP1, identified by our laboratory, is the first member of the evolutionary conserved Cysteine-RIch Secretory Protein (CRISP) family, Evidence indicates the existence of two populations of CRISP1 in sperm: a major one, loosely bound, released during capacitation and proposed to act as a decapacitating factor, and a minor one, strongly associated, that remains on sperm after capacitation and proposed to participate in fertilization. Recent results suggest that epididymal vesicles called epididymosomes, would be involved in the strong association of CRISP1 to sperm. Consistent with its localizations in the dorsal region of capacitated sperm and equatorial segment of acrosome-reacted cells, CRISP1 is involved in both sperm-ZP binding and gamete fusion through its interaction with egg-complementary sites. The potential roles of CRISP1 in capacitation and fertilization were further supported by the finding that capacitated sperm from CRISP1 ?knock out? animals exhibited low levels of protein tyrosine phosphorylation and presented an impaired ability to fertilize zona-intact and zona-free eggs. In spite of this, CRISP1-deficient mice were fertile, suggesting that testicular CRISP2, also involved in gamete fusion, and/or other CRISP homologue proteins, would compensate for the lack of CRISP1. In agreement with our observations in rodents, results indicate the participation of both human epididymal CRISP1 and testicular CRISP2 in human gamete fusion through its interaction with binding sites in the human egg. Moreover, our observations revealed the participation of hCRISP1 in sperm-ZP interaction through its binding to human ZP3. Finally, the recent finding that seminal plasma CRISP3 also remains in human sperm after capacitation and acrosome reaction, suggests a role for this protein in human gamete interaction. Together, these results support both the participation of CRISP proteins in different stages of fertilization and a functional cooperation between homologues CRISP molecules as a mechanism to ensure the success of this important process.