Macrophage ubiquitin-specific protease 2 contributes to motility, hyperactivation, capacitation, and in vitro fertilization activity of mouse sperm.

Abstract

Macrophages are innate immune cells that contribute to classical immune functions and tissue homeostasis. Ubiquitin-specific protease 2 (USP2) controls cytokine production in macrophages, but its organ-specific roles are still unknown. In this study, we generated myeloid-selectiveUsp2 knockout (msUsp2KO)miceand specifically explored the roles of testicular macrophage-derived USP2 in reproduction. The msUsp2KOmice exhibited normal macrophage characteristics in various tissues. In the testis, macrophage Usp2 deficiency negligibly affected testicular macrophage subpopulations, spermatogenesis, and testicular organogenesis. However, frozen-thawed sperm derived from msUsp2KO mice exhibited reduced motility, capacitation, and hyperactivation. In addition, macrophage Usp2 ablation led to a decrease in the sperm population exhibiting high intracellular pH, calcium influx, and mitochondrial membrane potential. Interrupted pronuclei formation in eggs was observed when using frozen-thawed sperm from msUsp2KO mice for in vitro fertilization. Administration of granulocyte macrophage-colony stimulating factor (GM-CSF), whose expression was decreased in testicular macrophages derived from msUsp2KO mice, restored mitochondrial membrane potential and total sperm motility. Our observations demonstrate a distinct role of the deubiquitinating enzyme in organ-specific macrophages that directly affect sperm function.