Expression of epithelial cadherin in mammalian sperm and oocytes and evidence on its participation in gamete interaction. Studies in human, murine and bovine models

VAZQUEZ-LEVIN MH Y COL

Plymouth, New Hampshire, EEUU

Congreso; Gordon Research Conference: Fertilization and Activation of Development; 2007

Gordon Research Conferences

El resumen es enviado a los organizadores para considerar su aceptacion al congreso (Jornadas de cupo limitado, 150-200 personas de todo el mundo). Expression of epithelial cadherin in mammalian sperm and oocytes and evidence on its participation in gamete interaction. Studies in human, murine and bovine models   Vazquez-Levin, MH; Marin-Briggiler, CI; Caballero, JG; Veiga, MF; Matos, ML; Furlong, LI; Lapyckyj, L; Gabrielli, N; Lentz, EM. Instituto de Biología y Medicina Experimental, CONICET. Buenos Aires, Argentina. mhvaz@dna.uba.ar   Epithelial cadherin (E-cadherin) is a transmembrane glycoprotein involved in Ca+2 dependent cell-cell adhesion. Evidence on the presence of E-cadherin in human and rat spermatozoa was previously reported. Immunocytochemical analyses done by our group confirmed these findings for human sperm and oocytes, and extended them to the murine and bovine gametes. In all species studied, E-cadherin was immunolocalized in subcellular regions described to participate in gamete interaction during fertilization. The aim of this study was to characterize the expression of E-cadherin in the reproductive tract (mRNA and protein forms) and gametes and to evaluate its involvement in gamete interaction. Expression of the E-cadherin mRNA in the epididymis was confirmed by RT-PCR; immunohistochemistry analysis revealed protein localization in epithelial cells from caput, corpus and cauda tissue sections. Moreover, E-cadherin signal was stronger in cauda epididymal spermatozoa compared that that in caput sperm cells, suggesting protein addition/unmasking during epididymal transit. The full length 122 KDa E-cadherin protein was identified by Western immunoblotting of epididymal extracts of all three species, as well as in epididymal (mouse and bovine) and ejaculated (bovine and human) spermatozoa, and in oocytes; in addition, C-terminal and N-terminal truncated forms were also identified in sperm cells and in cauda epididymal plasma, in agreement with reports in cell lines, tissues and fluids describing the presence of several E-cadherin protein isoforms.  Participation of E-cadherin in fertilization was evaluated by testing the ability of specific antibodies to interfere with gamete interaction. The Hemizona-Assay (HZA) and the hamster egg Sperm Penetration Assay (SPA) were performed in the human model, and standard in vitro fertilization (IVF) protocols were carried out in the mouse and bovine models. In the HZA, sperm adhesion to the ZP was impaired in sperm preincubated with anti Ecad antibodies ( P<0.05); similarly, sperm penetration was significantly diminished in the SPA when eggs were preincubated with the anti E-cadherin antibody (P<0.05). In agreement with these findings, a significant inhibition of fertilization was observed in the bovine and murine models when spermatozoa were preincubated with anti E-cadherin antibodies (P<0.001). In summary, the studies done in human, mouse and bovine models a) have characterized the expression of E-cadherin in the epididymis and gametes, and b) have demonstrated the ability of specific antibodies towards E-cadherin to significantly inhibit sperm-egg interaction.