Localization of epithelial cadherin in frozen thawed bull sperm in different functional states.

CABALLERO J; CETICA P; DALVIT G; VAZQUEZ-LEVIN MH

Buenos Aires, Argentina

Congreso; VII Jornadas Multidisciplinarias de la Sociedad Argentina de Biologia; 2005

Sociedad Argentina de Biologia

 Epithelial cadherin (E-cad) is a Ca+2 dependent cell-cell adhesion glycoprotein. Its presence has been reported in human and murine sperm, and data suggest its participation in fertilization. The aim of the study was to assess E-cad localization in frozen-thawed bull sperm under experimental conditions that resemble sperm functional changes occuring during fertilization. Evaluations (n=3/animal) were done in sperm from semen of 5 fertile Holstein bulls, as follows: 1)Frozen-thawed cells (semen extender removal with Sp-TALP), 2)Motile sperm selected by glass wool column filtration, 3)Motile sperm incubated in media with 60ìg/ml heparin (control: same+5mM glucose) to promote capacitation, and 4)Capacitated(cap) sperm incubated with 100ìg/ml Lysophosphatidylcholine (LPC) to induce acrosomal exocytosis. E-cad localization was done by immunocytochemistry with a specific anti E-cad antibody (Santa Cruz Biotech). In all cases, % live sperm , % progressive motile sperm and vigor (0–5 scale), capacitating status (chlortetracycline staining), and acrosome integrity (FITC- Pisum Sativum Agglutinin; FITC-PSA) was measured. In frozen-thawed and selected motile sperm (21±2% cap-sperm, 98±1% with intact acrosome; average ± SEM), a strong signal for E-cad was observed in the apical ridge, accompanied with a weak staining in the acrosome and post-acrosomal regions (63±3%; 77±2%; respectively). Under capacitating conditions (57±1% cap-sperm, 87±1% with intact acrosome), sperm were immunoreactive to E-cad in the apical ridge (57±6%) although no staining was observed in the acrosome. LPC-acrosome reacted (44±2% acrosome reaction) sperm lost the E-cad signal over the apical ridge in all cases, and showed an immunoreaction in the sperm head, suggesting E-cad localization in the inner acrosomal/nuclear membrane (54±4%) and in the equatorial segment (21±5%). In conclusion, E-cad is present in non capacitated, capacitated and acrosome reacted bull sperm, localized in cell regions proposed to participate in the interaction with oviductal cells and oocyte envelopes.