PROTEIN KINASE A LOCALIZATION IS CRITICAL FOR SPERM CAPACITATION

CARLA RITAGLIATI; PABLO E VISCONTI; CINTIA V STIVAL; CAROLINA BARO GRAF; DARIO KRAPF; GUILLERMINA M LUQUE; MARIANO G BUFFONE

CORDOBA

Congreso; 52th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2016

Capacitation is the process that renders sperm able to fertilize. It is characterized by a shift in the motility pattern (hyperactivation) and acquisition of acrosome responsiveness. Protein Kinase A (PKA) is known as a key player during capacitation events, coordinating downstream events such as membrane hyperpolarization and hyperactivation. PKA is activated early during capacitation due to a rapid increase of intracellular cAMP. However, current evidence supports the hypothesis that proper localization of the enzyme is also crucial for its regulation, either positioning the kinase in close contact with its substrates or alternatively, refraining contact from them. Here, we address the role of PKA anchoring to AKPAs through the usage of a permeable peptide named st-HT31, to study this type of PKA regulation in capacitation and during acrosome reaction (AR) using mouse sperm. Delocalization of PKA blocked both its activity as well as tyrosine phosphorylation. Moreover, this blockade prevented membrane hyperpolarization of sperm. In this regard, st-HT31 also prevented the acrosome reaction and in vitro fertilization. Worth noticing, even though the biological activity of PKA was affected, the chemical activity of PKA was not impaired, as addressed by in vitro activity of PKA in the presence of st-HT31. Our results uncover a new type of PKA regulation during sperm capacitation.