Background and objective: Protein phosphatase 3 catalytic subunit gamma (PPP3CC) and protein phosphatase 3 regulatory subunit B, beta (PPP3R2) are respectively the catalytic and regulatory subunits of calcineurin in sperm. Deficiency in either protein causes impaired sperm motility leading to male infertility. Many cases of sterility are attributed to asthenozoospermia (AZS); however, it remains unknown whether PPP3CC and PPP3R2 are related to AZS.

Material and methods: Quantitative PCR and Western blotting were used to investigate the expression levels of PPP3CC and PPP3R2 in the spermatozoa of patients with AZS and to explore the clinical significance.

Results: Two calcineurin inhibitors cyclosporine A (CsA) and tacrolimus (FK506) markedly impaired the total motility and progressive motility of human sperm, indicating that PPP3CC or PPP3R2 might be involved in AZS. PPP3CC mRNA and protein expression was lower in the ejaculated spermatozoa of patients with AZS than in normal sperm (NS). Correlation analysis showed that PPP3CC protein expression correlated positively with progressive motility (r = 0.2592, P 0.05); however, there were no significant differences in PPP3R2 mRNA and protein levels between AZS and NS.

Conclusion: These findings suggest that the abnormal expression of PPP3CC rather than PPP3R2 might be a pathological factor or indicator in AZS. Thus, PPP3CC may be a potential therapeutic or diagnostic target for some cases of male infertility.