Mycobacterium tuberculosis ACTIVATES AUTOPHAGY BY A PI3K INDEPENDENT PATHWAY Recalde GM, Rovett A, GarcíaV, Colombo MI.

RECALDE, G.; ROVETTA, A.I.; GARCIA, V.; COLOMBO M.I.

Mar del Plata

Congreso; LI Reunion SAIB; 2015

SAIB (Sociedad Argentina de Investigación en Bioquímica y Biología Molecular)

Mycobacterium tuberculosis (Mtb) is the etiological agent of tuberculosis. During macrophage infection with Mtb theautophagy pathway is activated. Activation of this pathway can limit replication, but the mechanism remains unclear.The secretion system named ESX-1 is responsible for the secretion of 6 kDa early secreted antigenic target (ESAT-6)and 10 kDA culture filtrate protein (CFP-10). ESAT-6 is a hemolysin that is secreted in a homodimeric complex withCFP-10. We observed the recruitment of the autophagic protein LC3 to phagosomes containing wild type Mtb, butnot to a mutant deficient for the ESAT-6 protein. To study this in more detail we generated and purified a fusionprotein CFP-10/ESAT-6. A significant increase in the autophagy levels was observed in a Raw 267.4 cell line. DQBSAand dextran assays show a normal transport and degradation of vesicles content excluding the possibility thatautophagy increase is due to interference in vesicular traffic. Interestingly our results indicate that the incrementobserved in autophagy is independent of PI3K but related to the EPAC pathway, as autophagy levels decreased by theuse of a specific stimulator of EPAC protein. All together these results are intended to elucidate the effect of theantigenic protein ESAT-6 at the molecular level and could help to understand the role of this protein in the Mtbinfection process.