Analysis of molecules for fertilization on human spermatozoa and oocytes

点击翻译按钮获取中文摘要

CD46 (membrane cofactor protein) acts to down-regulate complement cascade activity by binding complement components C3b and also acts as the cell surface receptor for measles virus.The extra-cytoplasmic components of the molecule are composed of four short consensus repeat (SCR) regions.SCR-1 is related to the down-regulation of complement activity and SCR-2 is a main domain of the measles virus fusion receptor.In our study, we revealed a novel SCR-3 related function in fertilization.We performed the hamster oocyte penetration test using the addition of antibodies against SCR-1, 2, and 3 of CD46 molecule.The anti-SCR-3 monoclonal antibodies reduced the penetration of human spermatozoa to the hamster oocytes in a dose-dependent manner, but did not inhibit the sperm binding to the oocytes.We concluded that CD46, especially SCR-3, was a fusion receptor of human spermatozoa to the oocyte and a marker of the fertilization capacity of human spermatozoa.We then developed a new method to assess the fertilization capacity of human spermatozoa by a two-color staining using fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (FITC-PSA) and anti-CD46 monoclonal antibody.The two-color staining revealed four staining patterns of acrosomal region.We defined PSA-positive/CD46 negative spermatozoa as acrosome-intact, PSA-negative/CD46 positive spermatozoa as acrosome-reacted, PSA-negative/CD46 negative spermatozoa as acrosome-damaged.The percentage of acrosome-reacted spermatozoa increased more rapidly than those of acrosome-damaged spermatozoa with the incubation time.The percentage of acrosome-reacted spermatozoa at the 4-hour incubation was related to fertilization in the clinical human IVF.