Expression of epithelial cadherin in mouse epididymis, sperm localization and assessment of its participation in fertilization

VEIGA F; LENTZ EM; MARÍN BRIGGILER CI; CHOREN V; CAMEO M; VINCENTI A; FORNÉS M; VAZQUEZ-LEVIN M

Seattle, Washington, USA

Congreso; 30th Annual Meeting American Society of Andrology; 2005

American Society of Andrology

During epididymal transit, sperm acquire the ability to fertilize the oocyte; the epididymis provides with proteins that confer such function. Epithelial cadherin (Ecad) is an adhesion molecule described to be expressed in the human and rat epididymis. Studies from our group have shown presence of Ecad in human sperm and oocytes, and suggested its participation in gamete interaction (Vazquez-Levin et al, ASA 2003). The aim of this study was to evaluate: 1) the expression of Ecad in the mouse epididymis, 2) its presence and localization in epididymal sperm, and 3) its participation in fertilization. Studies were done with a specific polyclonal antibody towards Ecad (Santa Cruz Biotech., Santa Cruz, USA). Expression of Ecad in the epithelium of caput, corpus and cauda epididymis was confirmed by immunohistochemistry; Western immunoblotting of epididymal protein extracts revealed a 127 KDa form, also found in sperm extracts from cauda epididymis. RT-PCR analysis confirmed the presence of epididymal Ecad transcripts. Immunocytochemistry of epididymal sperm showed a strong signal in the acrosomal and postacrosomal region in a variable percentage of cells (caput=25-78%, corpus=50-84%, cauda=16-79%; n=3); immuno-electron microscopy analysis confirmed Ecad localization in the plasma membrane of the acrosomal region. In addition, Ecad localized to the sperm tail in all cells evaluated. Sperm preincubation with anti Ecad (20 mg/ml) resulted in the inhibition of in vitro fertilization (anti Ecad: 49±8 % fertilized oocytes relative to control; n=5). The studies describe the expression of Ecad in mouse epididymis and its presence and localization in the sperm head and tail; in addition, they provide preliminary evidence suggesting its involvement in mouse fertilization.