Mouse anti-Human ADAM2 monoclonal antibody, clone 5B3

Past work indicated that sperm from mice deficient in the inositol polyphosphate 5-phosphatase Inpp5b have reduced ability to fertilize eggs in vitro and reduced epididymal proteolytic processing of the sperm protein A Disintegrin and A Metalloprotease 2 (ADAM2). On the basis of these data, our central working hypothesis was that reduced ADAM cleavage would correlate with reduced sperm-egg binding and fusion and in turn with reduced male fertility in Inpp5b(-/-) mice. Multiple endpoints of reproductive functions [mating trials, in vitro fertilization (IVF) assays and ADAM2 and ADAM3 cleavage] were investigated on a male-by-male basis, with pair-wise correlation analysis used to assess the relationships between these various parameters. Motile sperm from Inpp5b(-/-) mice showed significantly reduced fertilization of zona pellucida-free eggs due to reduced binding to the egg plasma membrane and subsequent fusion. Localization of a mouse sperm protein required for gamete fusion, IZUMO1, appears normal in Inpp5b-null sperm. To our surprise and differing from previous reports, we found that ADAM cleavage was only modestly impaired in numerous Inpp5b-null males and varied between individual animals. Performance in mating trials also differed from past reports. The pair-wise correlation analysis revealed that ADAM2 and ADAM3 cleavage was positively correlated, suggesting that processing of these proteins occurs by related/identical mechanisms, but otherwise, there were few correlations between the reproductive endpoints examined here. Nevertheless, this work provides detailed analysis of the Inpp5b(-/-) phenotype and also a blueprint for multivariate analysis to examine relationships between molecular characteristics and in vitro and in vivo physiological functions.

A Disintegrin And Metalloprotease (ADAM) family members expressed in male reproductive tissues are divided phylogenetically into three major groups. In the present study, we analyzed six ADAMs in one of the groups (ADAMs 4, 6, 24, 26, 29, and 30) of which function is largely unknown. Our results showed that most of the ADAMs undergo unique processing during sperm maturation and are located at the surface of sperm head. We found that the levels of ADAM4 and ADAM6 are dramatically reduced in Adam2 and Adam3 knockout sperm defective in various fertilization processes. We observed premature processing of ADAM4 in the Adam3-null mice. Furthermore, we obtained a result showing complex formation of ADAM6 with ADAM2 and ADAM3 in testis. Taken together, these results disclose involvement of ADAM4 and ADAM6 in a reproductive ADAM system that functions in fertilization.