CALCIUM SIGNALING: THE COMMUNICATION BETWEEN INTRACELLULAR Ca2+ STORES IN HUMAN SPERM

ARIAS RJ; DARSZON A; TREVIÑO CL; TREVIÑO CL; MATA-MARTINEZ E; MAYORGA LS; MATA-MARTINEZ E; MAYORGA LS; ARIAS RJ; DARSZON A

Paraná

Congreso; LIV Reunión Anual de la Sociedad Argentina de investigaciones en bioquímica y Biología Molecular; 2018

SAIB

Calcium (Ca2+) and cAMP signaling are essential in regulating processes required after sperm ejaculation that lead to fertilization, including the acrosome reaction (AR). This process is necessary for sperm to traverse the egg envelope and to expose a fusogenic membrane that allows egg-sperm fusion. Progesterone and ZP3, the most studied AR inducers, elicit an intracellular Ca2+ increase needed for AR in human sperm. This increase is mediated by a first Ca2+ influx but also the intracellular calcium stores are involved. It is know that intracellular Ca2+ stores play a central role in the regulation of [Ca2+]i and in the generation of complex Ca2+ signals such as oscillations and waves. In a previous report we have proposed that in human sperm the cAMP analogue 8-(p- chlorophenylthio)-2´-O-methyladenosine-3´, 5´-cyclic monophosphate (8-pCPT-2´-O-Me-cAMP) elicits an intracellular Ca2+ release which is involved in AR. The aim of this study was investigate which Ca2+ stores and Ca2+ channels are involved in the 8-pCPT-2´-O-Me-cAMP pathway in human sperm. We performed real time dynamic assays in calcium-free medium -with high time and spatial resolution- using fluorescent Ca2+ sensors. We found that 8-pCPT-2´-O-Me-cAMP, induce a Ca2+ wave that starts in the posterior neck region and propagates to the acrosome region. This calcium response was sensitive to NED-19 and Thapsigargin, highlighting the participation of different Ca2+ stores, ionic channels (Two Pore Channels) and Ca2+-ATPasas (SPCA).