Role of cell adhesion molecule nectin-3 in spermatid development.

Seminiferous epithelia of the testes contain two types of intercellular junctions: Sertoli-Sertoli junctions and Sertoli-spermatid junctions. The former junctions are equipped with tight and adherens junctions while the latter junctions are not. Ca2+ -independent immunoglobulin-like cell-cell adhesion molecules, nectin-2 and nectin-3, asymmetrically localize at the Sertoli cell side and at the spermatid side of Sertoli-spermatid junctions, respectively. They heterophilically trans-interact to make contact between the two cells. Nectin-2(-/-) mice have shown male-specific infertility, disrupted Sertoli-spermatid junctions and morphologically impaired spermatid development. Here we report testicular phenotypes of nectin-3(-/-) mice exhibiting male-specific infertility. Nectin-3(-/-) mice had defects in the later steps of sperm morphogenesis including distorted nuclei and abnormal distribution of mitochondria, as well as in localization of nectin-2 at the Sertoli-spermatid junctions. Transplantation of wild-type spermatogenic stem cells into the nectin-3(-/-) testes partially rescued these defects in sperm morphogenesis. These results indicate that the heterophilic trans-interaction between nectin-2 and nectin-3 is essential for the formation and maintenance of Sertoli-spermatid junctions that plays a critical role in spermatid development.