E-cadherin: identification and characterization of human sperm protein forms

LENTZ, EZEQUIEL; MARIN BRIGGILER, CLARA I; RIVERO, CINTIA; VAZQUEZ LEVIN, MÓNICA

Buenos Aires

Congreso; Reunión Anual de la Sociedad Argentina de Biología; 2003

E-CADHERIN: identification and cHaracterization of human sperm protein forms Lentz EM, Marín-Briggiler CI, Rivero C, Vazquez-Levin MH. IBYME-CONICET. Vuelta de Obligado 2490. 1428 - Buenos Aires, Argentina. Cadherins (cad) constitute a distinct superfamily of membrane glycoproteins involved in cell adhesion. Classical cad have five extracellular, one transmembrane and one cytoplasmic domains. Presence of epithelial cad (E-cad) has been reported in ejaculated sperm, and its involvement in fertilization has been suggested from studies showing an inhibitory effect of specific antibodies upon gamete interaction. Objective: To identify E-cad protein forms present in human sperm. Materials & Methods: Protein extracts from human sperm, epididymis and testes were prepared in Laemmli sample buffer. In addition, sequential extraction of sperm proteins was performed (1 M NaCl; 1% Triton X100; 1% SDS). E-cad forms were identified by Western imunoblotting and immunoprecipitation. Results: Four high molecular weight E-cad forms (122, 105, 97 and 86 KDa) were detected in protein extracts of sperm incubated with 1% SDS. E-cad122 was also detected in epididymal and testicular extracts. E-cad105 was resistant to Triton X100 treatment. E-cad97 was extracted with detergents and was present in capacitated sperm. Moreover, E-cad97 was detected with an antibody towards the second extracellular domain but not with one against the cytoplasmic domain. E-cad86 was removed from sperm by 1 M NaCl extraction, and its amount decreased in capacitated cells. E-cad86 was also immunoprecipitated from seminal plasma proteins. Conclusions: Four sperm E-cad forms were identified in human sperm: E-cad122, which resembles the mature transmembrane protein reported in other tissues; E-cad105 and E-cad97, both transmembrane forms; and E-cad86, a peripheral protein, probably corresponding to the soluble E-cad ectodomain released from the cell surface by proteases.