EFFECTS OF MODULATORS OF PROTEIN-KINASE-C ON HUMAN SPERM CAPACITATION

Objective: To examine the effects of stimulators or inhibitors of prot ein kinase C on capacitation and protein phosphorylation in human sper m. Design: Capacitated sperm treated with or without modulators of pro tein kinase C were monitored by the chlortetracycline fluorescence ass ay. Capacitation was confirmed by the ability of sperm to undergo the acrosomal reaction in response to mouse zonae pellucidae. P-32-labeled sperm phosphoproteins were analyzed by one-dimensional gel electropho resis to detect the effect of protein kinase C stimulator, 12-O-tetrad ecanoyl-phorbol-13-acetate, on protein phosphorylation. Results: The t reatment of sperm with protein kinase C stimulators resulted in the fo llowing. [1] the rapid appearance of the clear perimeter pattern, feat uring distribution of fluorescence over the entire head exhibiting a b right perimeter and bright midpiece; [2] an accelerated ability to und ergo the acrosomal reaction; and [3] an enhanced phosphorylation of 57 .5-kd sperm phosphoprotein. Furthermore, these stimulatory effects wer e inhibited by protein kinase C inhibitors. Conclusion: Protein phosph orylation mediated by protein kinase C may be involved in the regulati on of human sperm capacitation.