Progesterone increases intracelullar calcium by a Catsper independent mechanism in human sperm.

ARIAS RJ; POBLETE S; SOSA CM; MAYORGA LS; JUSTRIBÓ G; DE BLAS GA

Mendoza

Congreso; XXXIV Reunión científica anual de la Sociedad de Biología de Cuyo; 2016

Sociedad de Biología de Cuyo

Calcium signaling is a key regulatory mechanism in sperm function(capacitation, hyperactivation and acrosome reaction). In mammalian sperm, theplasma membrane ion channel CatSper is central to [Ca2+]i signaling,but there is good evidence that Ca2+ stored in intracellularorganelles is also functionally important. Previous works have shown thatprogesterone acts on CatSper calcium channels. These ion channels are foundexclusively at the plasma membrane of the principal piece of the sperm tail.The aim of this study was to investigate whether progesterone can trigger anintracellular calcium increase independent of CatSper and extracellularcalcium. We used fluorescent calcium sensors in real time dynamic assays insingle cell -with high speed and spatial resolution- and populationmeasurements in a spectrofluorimeter. Capacitated human sperm were loaded withFluo3-AM or Fura2-AM, then incubated in a calcium-free medium and treated withprogesterone in absence or presence of intracellular calcium modulators(tapsigargin, dantrolene, xestospongin C, etc). We found that in the absence ofextracellular Ca2+, progesterone induces a calcium increase thatstarts in the midpiece/neck region and propagates to the acrosome region. Thesefindings indicate that progesterone can trigger the release of calcium fromintracellular calcium stores by a CatSper independent mechanism.