Epithelial cadherin and sperm-egg interaction: studies in human, mouse and bovine models.

VAZQUEZ-LEVIN MH; MARÍN-BRIGGILER CI; VEIGA MF; CABALLERO JG; LENTZ EM; ZACCHI N; RIVERO CW; FURLONG LI

Uspallata, Mendoza, Argentina

Congreso; Conferencia en la XXIII Reunión Científica Anual de la Sociedad de Biologia de Cuyo; 2005

Sociedad de Biologia de Cuyo

(resumen enviado, finalmente solo publicado en CD entregado con los materiales del congreso)Epithelial cadherin (Ecad) is a membrane glycoprotein involved in Ca+2 dependent cell adhesion events. Studies done by our group were aimed at: 1) localizing Ecad in human, mouse and bovine gametes, 2) evaluating its involvement in gamete interaction, 3) identifying Ecad protein form(s) in the male tract, and 4) characterizing the sequence encoding human epididymal Ecad. Immunocytochemical studies done in human, mouse and bovine sperm showed Ecad localization in regions proposed to be involved in the interaction with oviductal cells and oocyte envelopes. In addition, a specific Ecad immunostaining was detected in the zona pellucida (ZP) and the plasma membrane of bovine and human oocytes, and in the oolemma of mouse and hamster eggs devoid of ZP. Ecad participation in sperm-egg interaction was suggested by the inhibitory effect of anti Ecad antibodies in the HemiZona Assay and the Hamster Egg Sperm Penetration Assay (P<0.02); in agreement, mouse in vitro fertilization was blocked by anti Ecad antibodies (P<0.001). Ecad protein isoforms (122, 105, 97 and 86 KDa) present in human sperm and seminal plasma fluid were identified and partially characterized. Expression of Ecad in human and mouse epididymis was confirmed by immunohistochemistry and Western immunoblotting. Molecular studies identified a novel human epididymal mRNA that would result from alternative splicing, giving rise to a truncated Ecad form. Protein expression and functional analysis of the variant Ecad mRNA will contribute to the understanding of Ecad function(s) in mammalian fertilization.