The alteration of PLCζ protein expression in unexplained infertile and asthenoteratozoospermic patients: A potential effect on sperm fertilization ability

Failed oocyte activation has been observed in unexplained infertile (UI) and asthenoteratozoospermic (AT) men. The deficiency of phospholipase C-zeta (PLCzeta) could be a possible reason for such failures and has not been studied yet. We investigated the expression and localization of PLCzeta protein in the sperms of patients with UI and AT conditions. The relationships between PLCzeta-related parameters with male age, sperm characteristics, DNA integrity, and cellular maturity were assessed. Semen samples were collected from fertile (n = 40), UI (n = 40), and AT (n = 40) men. Subsequently, semen analysis, DNA fragmentation, hyaluronic acid-binding ability, and PLCzeta level along with its distribution were evaluated using computer-assisted sperm analyzer, sperm chromatin structure assay (SCSA), hyaluronic acid-binding assay (HBA), western blot analysis and immunofluorescence microscopy, respectively. Unlike SCSA, the values of HBA, and PLCzeta expression were significantly reduced in UI and AT patients compared to fertile men, whereas no significant differences were observed among the experimental groups in terms of PLCzeta localization patterns. The regression analysis also showed that HBA is the only variable associated with PLCzeta levels. Furthermore, the correlation of male age with PLCzeta localization in postacrosomal, equatorial, and acrosomal+postacrosomal+equatorial (A+PA+E) patterns, as well as the relation of normal morphology, with the (A+PA+E) pattern, remained in the regression model. Our findings indicated that reduced PLCzeta level along with the increased DNA fragmentation and impaired maturation may be possible etiologies of decreased fertilization in the studied subjects.