Both protein and non-protein components in extracellular vesicles of human seminal plasma improve human sperm function via CatSper-mediated calcium signaling.

Study Question: What is the significance and mechanism of human seminal plasma extracellular vesicles (EVs) in regulating human sperm functions?

Summary Answer: EV increases the intracellular Ca2+ concentrations [Ca2+]i via extracellular Ca2+ influx by activating CatSper channels, and subsequently modulate human sperm motility, especially hyperactivated motility, which is attributed to both protein and non-protein components in EV.

What Is Known Already: EVs are functional regulators of human sperm function, and EV cargoes from normal and asthenozoospermic seminal plasma are different. Pre-fusion of EV with sperm in the acidic and non-physiological sucrose buffer solution could elevate [Ca2+]i in human sperm.

Involvement of Ca and ROS signals in nickel-impaired human sperm function.

As one of the main environmental pollutants and occupational hazards, nickel has been reported to have mutagenic, carcinogenic, and teratogenic properties, as well as reproductive toxicity. However, how nickel affects human reproduction is still unclear. In this study, the toxicity of nickel on human sperm and the underlying mechanisms were evaluated in vitro.

Na/H Exchangers Involve in Regulating the pH-Sensitive Ion Channels in Mouse Sperm.

Sperm-specific K ion channel (KSper) and Ca ion channel (CatSper), whose elimination causes male infertility in mice, determine the membrane potential and Ca influx, respectively. KSper and CatSper can be activated by cytosolic alkalization, which occurs during sperm going through the alkaline environment of the female reproductive tract. However, which intracellular pH (pH) regulator functionally couples to the activation of KSper/CatSper remains obscure.

IP3R Channels in Male Reproduction.

As a second messenger in cellular signal transduction, calcium signaling extensively participates in various physiological activities, including spermatogenesis and the regulation of sperm function. Abnormal calcium signaling is highly correlated with male infertility. Calcium signaling is mainly regulated by both extracellular calcium influx and the release of calcium stores.