The role of mitochondria in calcium signaling and human sperm physiology activated by progesterone

ARIAS RJ; GARCIA A; DE BLAS GA; VARGAS S; HÄRTEL S; MATA-MARTINEZ E; MAYORGA LS

Paraná, Entre Rios

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

SAIB

The main function of mitochondria is the production of ATP through the electron transport chain and lipid oxidation. In addition, this organelleplays an important role in Ca2+ buffering and signaling, shaping and extending the kinetics of Ca2+ signals. Calcium signaling is a keyregulatory mechanism in sperm functions such as capacitation, motility, hyperactivation, chemotaxis and acrosome reaction. Progesterone (Pg)has been associated with several processes of sperm physiology, since it directly activates membrane Ca2+ channels. Our group have previouslyobserved that Pg induces an intracellular calcium increase in sperm in media with ≈100nM [Ca2+]. It is unclear which calcium reservoirs of thesperm are involved in this calcium increase. The aim of this study was to investigate the role of mitochondria in calcium signaling involved inthe Pg pathway and others functions such as acrosomal reaction and motility parameters in human spermatozoa. To this end, we loadedcapacitated human sperm with fluorescent calcium sensor Fluo3-AM, then treated with progesterone in absence or presence of mitochondrialinhibitors in medium containing different [Ca2+]. We used real time dynamic assays with high speed and spatial resolution, in single cellsanalysis, and computer software to analyze cellular motility parameters. We observed that Pg generated increases of intracellular Ca2+ withparticular kinetics and patterns in media with different [Ca2+]. We also noticed that mitochondrial inhibitors altered the Ca2+ patterns andkinetics previously observed. These results suggest that mitochondria participates in calcium signaling in response to Pg.