CR16 forms a complex with N-WASP in human testes.

The expression of corticosteroids and regional expression 16 (CR16) and neural Wiscott-Aldrich syndrome protein (N-WASP) was studied in the testes of men with idiopathic azoospermia by (1) immunohistochemistry and Western blot to detect the expression of CR16 and N-WASP protein, (2) reverse transcription with the polymerase chain reaction (RT-PCR) to determine the amounts of CR16 and N-WASP mRNA, and (3) double-staining immunofluorescence and laser scanning confocal microscopy (LSCM) to demonstrate the co-localization of CR16 and N-WASP proteins. Immunohistochemistry revealed CR16 and N-WASP proteins in the Sertoli cells, specifically in the Sertoli cell-spermatogenic cell junctions (SspJs) in the epithelium of the seminiferous tubules. RT-PCR indicated that the relative amounts of CR16 and N-WASP mRNA were significantly decreased in men with idiopathic azoospermia, although the ratio of CR16 and N-WASP mRNA was approximately 1:1 in both groups of men. Western blot showed the presence of the CR16 monomer and N-WASP in all tissues examined, but the relevant bands were paler in men with idiopathic azoospermia than those in healthy men. The distribution of CR16 and N-WASP was similar in the epithelium of seminiferous tubules based on double-staining immunofluorescence and LSCM, thereby suggesting that CR16 and N-WASP were co-localized in the SspJs as a CR16/N-WASP complex. The decreased levels of CR16 and N-WASP in the testes of men with idiopathic azoospermia compared with healthy men and the co-localization at the SspJs as a CR16/N-WASP complex in the epithelium of seminiferous tubules suggest that CR16 and N-WASP play a role in the pathogenesis of azoospermia.