COMMITMENT OF PROTEIN KINASE A IN THE REGULATION OF Na+/H+ EXCHANGE IN Trypanosoma cruzi

PEPPINO MARGUTTI, M.; REYNA, M.; USORACH, M.; VILLASUSO, A.; RACAGNI, G.

San Miguel de Tucumán

Congreso; XVII Annual Meeting of the Argentine Biology Society; 2015

Universidad Nacional de Tucumán

COMMITMENT OF PROTEIN KINASE A IN THE REGULATION OF Na+/H+ EXCHANGE IN Trypanosoma cruziPeppino Margutti, M., Reyna, M., Usorach, M., Villasuso, A., Racagni, G. Dept. Biol. Molecular. UNRC. Rio Cuarto (CBA). E-mail: mpeppino@exa.unrc.edu.arAdaptation processes of Trypanosoma cruzi during their life cycle involve the Ca2+ ion as an essential component. Ca2+ signals play an important role on the differentiation of epi- to tripomastigotes and during the invasion to the host cells. The objective of this work was to study the involvement of internal reservoirs in cytoplasmic calcium increases in epimastigote forms of T. cruzi during hyperosmotic stress. Mannitol caused the alcalinization of acid vacuoles, while in pre-incubated parasites with to inhibitor of Na+/H+ exchange (EIPA), a decrease was observed and a significant increase in treated parasites whit a competitive inhibitor of phosphodiesterases (IBMX) was noticed. Hyperosmotic stress induced Ca2+ release from the acidocalcisomes determined by changes in fluorescence of Fura-2/AM while pretreatment with EIPA also decreased ion signal. Furthermore, the release of calcium induced by mannitol increased when parasites were treated with the activator of PKA (dibutyryl-cAMP). In contrast, it decreased calcium release when cells were treated with an inhibitor of PKA (KT520). Througth the use of wester blot assays on isolated acidocalcisomes, the presence of Na+/H+ exchange of T. cruzi was demonstrated. Therefore, we infer that the hyperosmotic stress triggers signals that lead to the activation of PI-PLC-mediated Ca2+ release of acidocalcisomes, which is favored by alkalinization of the vacuole through the Na+/H+ exchange. This would be positively regulated by phosphorylation by PKC and PKA. These biochemical events may contribute to the adaptation of the parasite to the conditions present in the rectum of the insect vector and could be key steps in the process of differentiation.