Expression Patterns and Functional Implications of CMTM2 in Human Testis and Sperm

The CMTM family plays pivotal roles in various physiological and pathological processes, including those associated with the male reproductive system. Among them, CMTM2 exhibits specific expression in testicular tissue; however, its relationship with spermatogenesis, sperm function, and the underlying molecular mechanisms remains unclear. This study systematically investigated the localization of CMTM2 in human testis and sperm, as well as its correlation with spermatogenesis and sperm quality. The results revealed that CMTM2 expression was specifically localized in human testis, predominantly in germ cells, with significantly lower levels observed in sperm from patients with asthenozoospermia and teratozoospermia compared to normospermic individuals. Immunofluorescence analysis revealed that CMTM2 was predominantly localized in the middle piece of sperm, with significant reductions in infertile samples. Western blot analysis confirmed decreased CMTM2 levels in sperm from asthenozoospermia, oligozoospermia, and teratozoospermia patients, indicating a strong correlation between CMTM2 expression and sperm quality. Furthermore, CMTM2 expression positively correlated with sperm progressive motility, but not with sperm concentration, suggesting its potential role in regulating sperm motility in both normal and asthenozoospermia patients. The findings suggested a significant correlation between the CMTM2 expression and spermatogenesis as well as sperm quality, thereby providing valuable insights for further investigations into the molecular mechanisms involved. These results lay a foundational basis for exploring the potential roles of other members within the CMTM family in male reproduction.