A comparative study of capacitation-mediated changes in whole mouse sperm proteome

Mammalian spermatozoa acquire fertilizing ability in response to environmental factors enriched in the female reproductive tract, a process called capacitation. During capacitation, sperm undergo physiological changes that are accompanied by functional regulation of sperm proteins. However, the mechanism by which capacitation orchestrates sperm protein functions to modulate physiological characteristics remains unclear. Here, I analyzed capacitation-mediated global proteomic changes in mouse spermatozoa to unravel the underlying molecular association with the biological processes in sperm capacitation. I quantitatively compared 4,587 proteins identified by liquid chromatography-tandem mass spectrometry. Among them, the amounts of 47 and 180 proteins were reduced to over 1.5-fold (p < 0.05) and 1.3-fold (p < 0.1), respectively, and those of 11 and 60 proteins were increased over 1.5-fold (p < 0.05) and 1.3-fold (p < 0.1), respectively, in capacitated mouse sperm. Functional annotation of proteins reduced in capacitated sperm revealed that these proteins could be associated with lipid metabolism, RNA processing, and remodeling of the nuclear envelope structure. This result suggests that reactive oxygen species might be more generated for cholesterol efflux and the nucleus might undergo decondensation to form pronucleus in sperm during capacitation. In addition, functional annotation of proteins of which levels are increased in capacitated sperm represents that they could be involved in sperm structure. This study expands the molecular contribution to modulation of sperm functions and provides new insights into potential biological processes involving regulatory molecular machinery in capacitated sperm.