CROSSROADS TO SPERM ACROSOMAL RESPONSIVENESS: PKA, ACTIN DYNAMICS AND MEMBRANE HYPERPOLARIZATION

STIVAL, C. ; ROMAROWSKI, A.; ALVAU, A.; ARRANZ, S.E.; VISCONTI, P.; BUFFONE, M.; KRAPF, D.

Mar del Plata

Congreso; LI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

SAIB

Capacitation is the process by which mammalian sperm gain fertilizing capacity. It is characterized by acquisition of acrosomal-responsiveness (AR), which in turn is related to actin polymerization, membrane hyperpolarization, andactivation of PKA. The mechanisms underlying these events and the interplay between them remain unknown. We have shown that Src modulates hyperpolarization through regulation of SLO3, and that Src activation depends on PKA. Our aim is to deepen in the pathways underlying AR, in which the role of Src could interplay with actin dynamics to regulate SLO3. We studied the kinetics of actin dynamics by determining the G-actin/F-actin ratio, and observed a polymerization process towards the end of capacitation. However, we also detected a transient actin depolymerization that precedes the polymerization step. Our results indicate that Src is linked to these processes and that PKA is also necessary for actin polymerization. PKA is activated almost immediately after exposure tocapacitating condition. Although Src depends on PKA activation, its activated state is only observed after 15 min after the beginning of capacitation. Our data show that PKA directly phosphorylates Src at Ser17, which mightimpact on its later activation. Most importantly, PKA sustained activity is mandatory for the maintenance of Src activity throughout capacitation, that will later ensure AR.