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Calcium ions (Ca2+) play crucial roles in sperm motility and fertilization. The copine (CPNE) family comprises several Ca2+-dependent phospholipid-binding proteins. Of these, CPNE1 is extensively expressed in mammalian tissues; however, its precise role in testicular development and spermatogenesis is yet to be fully characterized. In this study, we used proteomics to analyze testicular biopsies and found that levels of CPNE1 were significantly reduced in patients with non-obstructive azoospermia (defective spermatogenesis) compared to those in patients with obstructive azoospermia (physiological spermatogenesis). In mice, CPNE1 is expressed at various stages of germ cell development and is associated with the Golgi apparatus. Ultimately, CPNE1 is expressed in the flagella of mature sperms. To further examine the role of CPNE1, we developed a Cpne1 knockout mouse model. Analysis showed that the loss of Cpne1 did not impair testicular development, spermatogenesis, or sperm morphology and motility in physiological conditions. When treated with gadolinium (III) chloride or 2-aminoethoxydiphenyl borate, known inhibitors of store-operated Ca2+ entry, Ca2+ signals and sperm motility were significantly compromised in wild-type mice; however, both mechanisms were conserved in KO mice. These results suggested that CPNE1 is dispensable for testicular development, spermatogenesis or sperm motility in physiological conditions. In addition, CPNE1 may represent a target of Ca2+ channel inhibitors and may therefore be implicated in the regulation of Ca2+ signaling and sperm motility.

Oligoasthenoteratozoospermia is a human infertility syndrome caused by defects in spermatogenesis, spermiogenesis, and sperm maturation, and its etiology remains unclear. Kelch-like 10 (KLHL10) is a component of ubiquitin ligase E3 10 (KLHL10) and plays an important role in male fertility. Deletion or mutation of the Klhl10 gene in Drosophila or mice results in defects in spermatogenesis or sperm maturation. However, the molecular mechanisms by which KLHL10 functions remain elusive. In this study, we identified a missense mutation (c.1528A→G, p.I510V) in exon 5 of KLHL10, which is associated with oligoasthenoteratozoospermia in humans. To investigate the effects of this mutation on KLHL10 function and spermatogenesis and/or spermiogenesis, we generated mutant mice duplicating the amino acid conversion using the clustered regularly interspaced palindromic repeat/caspase 9 (CRISPR/Cas9) system and designated them Klhl10I510V mice. However, the Klhl10I510V mice did not exhibit any defects in testis development, spermatogenesis, or sperm motility at ten-weeks-of-age, suggesting that this mutation does not disrupt the KLHL10 function, and may not be the cause of male infertility in the affected individual with oligoasthenoteratozoospermia.