Sperm Maturation and Motility in Kunming Mice Regulated by Protein Phosphatase PP1γ2

Purpose PP1γ2 is a testis- and sperm-specific type of protein phosphatase and it is a key enzyme essential for maturation, initiation and regulation of sperm motility. The regulation of PP1γ2 on sperm maturation and motility in Kunming mice was studied.

Method In the present study, the levels of phosphorylated and dephosphorylated PP1γ2 in caput and caudal epididymal spermatozoa under various conditions were examined via Western-blot, and the effects of two phosphatase inhibitors, i.e., okadaic acid (OA) and cyliculin A (CA) on motility in caput and caudal epididymal spermatozoa were also investigated.

Result The level of phosphorylated PP1γ2 was significantly higher (P<0.05) in caudal epididymal spermatozoa than that of caput spermatozoa. The level of phosphorylated PP1γ2 remained unchanged under the treatments of db-cAMP, IBMX or Ca²⁺. OA or CA significantly increased not only the level of phosphorylated PP1γ2 in caput and caudal epididymal spermatozoa but also the sperm motility (especially in caput epididymal spermatozoa).

Conclusion The enzyme activity of PP1γ2 changes with the phosphorylation and dephosphorylation of PP1γ2, thus, PP1γ2 exerts its roles on the regulation of sperm maturation and motility in the epididymis in Kunming mice. To be specific, the high activity of enzyme PP1γ2 in caput epididymal spermatozoa results in lower sperm motility whereas the low activity of enzyme PP1γ2 in caudal epididymal spermatozoa enhances motility significantly.