CONICET | Buscador de Institutos y Recursos Humanos

Mammalian sperm are unable to fertilize the egg before undergoinga series of biochemical and physiological changes in the femalereproductive tract, collectively known as capacitation. Functionally,capacitation is associated with changes in the sperm motility(hyperactivation) and with their ability to undergo the acrosome reaction.At the molecular level, capacitation correlates with activationof the cAMP-PKA pathway, increase in intracellular pH and Ca2+concentration, hyperpolarization of the plasma membrane potentialand increase in protein tyrosine phosphorylation. How these signalingpathways interact to induce hiperactivation and acrosomal responsiveness,is not well understood. Since mature sperm are transcriptionallyand translationally silent, they rely on PTM of proteinsmore than any other cell type. Therefore, it is an exceptional modelfor the study of signaling pathways based on PTM. The importanceof phosphorylation, an essential PTM in sperm physiology has beenwell established. Acetylation as a broad and abundant PTM comparablewith phosphorylation, however, has not been well analyzed.Recently, two groups identified 576 and 456 acetylated proteinsin capacitated and non-capacitated human sperm respectively, ofwhich 250 were present in both conditions. In the present work, westudied the role of acetylation in mouse sperm capacitation. WBand immune-localization analysis with anti-acetyl lysine antibodiesshowed lysine acetylation of several proteins spanning a wide massrange, both in the sperm head and tail. A significant increase in thefluorescence was detected in capacitated sperms. Pharmacologicalhyperacetylation was associated with increased PKA activity and,an increase in intracellular Ca2+, even in the absence of HCO3- andBSA. In addition, this PMT regulates hyperpolarization of the plasmamembrane and hyperactivation. These results point towards a keyrole of lysine acetylation in sperm capacitation.