PROGESTERONE TRIGGERS INTRACELLULAR CALCIUM WAVE BY A CATSPER-INDEPENDENT MECHANISM IN HUMAN SPERM

SOSA CLAUDIA*,; PAVAROTTI MARTÍN A; MAYORGA LUIS S; DE BLAS, GERARDO ANDRÉS

Mar del Plata

Congreso; 51 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2023

SAIB

Previous works have shown that progesterone acts on CatSper calcium channels. These ion channels are foundexclusively in the membrane of the sperm tail. Progesterone opens CatSper channels and triggers a fast increase inintracellular Ca2+. This ion is crucial for sperm functions, such as the regulation of capacitation, hyperactivation andacrosome reaction. The aim of this study was to investigate whether progesterone can trigger an intracellular calciumincrease in absence of extracellular calcium. We used fluorescent calcium sensors in real time dynamic assays insingle cell -with high speed and spatial resolution- and population measurements in a spectrofluorimeter. Capacitatedhuman sperm were loaded with Fluo3-AM, then incubated in a calcium-free medium and treated with progesterone.We found that in the absence of extracellular Ca2+, progesterone induces a calcium increase that starts in themidpiece/neck region and propagates to the acrosome region. These findings indicate that progesterone can triggerthe release of calcium from intracellular calcium stores by a CatSper independent mechanism