Defects in nuclear and cytoskeletal morphology and mitochondrial localization in spermatozoa of mice lacking nectin-2, a component of cell-cell adherens junctions

Nectin-2 is a cell adhesion molecule encoded by a member of the poliovirus receptor gene family. This family consists of human, monkey, rat, and murin e genes that are members of the immunoglobulin gene superfamily, Nectin-2 i s a component of cell-cell adherens junctions and interacts with 1-afadin, an F-actin-binding protein, Disruption of both alleles of the murine nectin -2 gene resulted in morphologically aberrant spermatozoa with defects in nu clear and cytoskeletal morphology and mitochondrial localization. Homozygou s null males are sterile, while homozygous null females, as well as heteroz ygous males and females, are fertile, The production by nectin-2(-/-) mice of normal numbers of spermatozoa containing wild-type levels of DNA suggest s that Nectin-2 functions at a late stage of germ cell development. Consist ent with such a role, Nectin-2 is expressed in the testes only during the l ater stages of spermatogenesis. The structural defects observed in spermato zoa of nectin-2(-/-) mice suggest a role for this protein in organization a nd reorganization of the cytoskeleton during spermiogenesis.