TRPV4 modulates sperm motility, fertilization, and hatching rates in chub mackerel

Achieving efficient fertilization in marine fishes remains a challenge for aquaculture, as molecular sensors translating seawater and ionic cues into sperm motility are poorly understood. Here, we identify the osmosensitive cation channel TRPV4 as a central regulator of sperm function in chub mackerel ( Scomber japonicus ), a commercially important species with recently established full life-cycle aquaculture. Quantitative PCR and immunohistochemistry revealed strong TRPV4 expression in sperm, predominantly localized to the flagellum and midpiece. Pharmacological activation of TRPV4 with RN1747 (100 nM) enhanced sperm motility by approximately 6% during the critical 30–50 s post-activation window (p < 0.05), increased amplitude of lateral head displacement (ALH; p < 0.05), and elevated intracellular Ca²⁺ levels approximately 2-fold (p < 0.05). In contrast, TRPV4 inhibition with RN1734 (1 µM) reduced motility by up to 95% and markedly impaired velocity, trajectory, and Ca²⁺ signaling. These cellular effects translated into reproductive outcomes: TRPV4 activation increased fertilization and hatching rates, whereas inhibition nearly abolished both (< 1%). Mechanistically, TRPV4 integrates osmotic and ionic cues from seawater to coordinate Ca²⁺-dependent flagellar dynamics and swimming behavior. Together, these findings establish TRPV4 as a key regulator of sperm function and reproductive success in marine teleosts, and as a promising pharmacological target for improving fertilization efficiency in aquaculture.