CCDC28A deficiency causes sperm head defects, reduced sperm motility and male infertility in mice.

Mature spermatozoa with normal morphology and motility are essential for male reproduction. The epididymis has an important role in the proper maturation and function of spermatozoa for fertilization. However, factors related to the processes involved in spermatozoa modifications are still unclear. Here we demonstrated that CCDC28A, a member of the CCDC family proteins, is highly expressed in testes and the CCDC28A deletion leads to male infertility. We found CCDC28A deletion had a mild effect on spermatogenesis. And epididymal sperm collected from Ccdc28a-/- mice showed bent sperm heads, acrosomal defects, reduced motility and decreased in vitro fertilization competence whereas their axoneme, outer dense fibers, and fibrous sheath were all normal. Furthermore, we found that CCDC28A interacted with sperm acrosome membrane-associated protein 1 (SPACA1) and glycogen synthase kinase 3a (GSK3A), and deficiencies in both proteins in mice led to bent heads and abnormal acrosomes, respectively. Altogether, our results reveal the essential role of CCDC28A in regulating sperm morphology and motility and suggesting a potential marker for male infertility.