THE SECRETED ALPHA-HEMOLYSIN OF S. Sureus ACTIVQTES THE AUTOPHAGIC RESPONSE IN THE HOST CELL

MESTRE MB; FADER, CM.; SOLA C AND COLOMBO M.I

XLIV reunión anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

Congreso; XLIV reunión anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2008

S. Aureus induce a caspase- independent cell death, with the participation of autophagy. This involved the sequestration of cytosolic component, organelles and microorganism in a vacuole, the autophagosome, which finally fuse with the lysosome. our propouse was identify the facto(s) and the signaling pathway that participate in the activation of the autophagic response caused by A. aureus alpha hemolisin is a pore forming  toxin  secreted by S. aureus.CHO cells overexpressing GFP-LC3 (an autophagic marker) was incubated with the toxin. this caused a marked ativation ao autophagy in concentration-dependent manner.In order to adress the toxin is the only secreted factor responsible for the activation of autophagy, CHO GFP-LC3 cells were infected with the following S. aureus strain: WT, a mutant deficient in alfa hemolisin (Hla-), and Hla- mutant expressing the alpha hemolisin plasmid. S. aureus WT as well the mutant expressing the plasmid stimulatedthe autophagy upon infection. In contrast, hla- was unable of activatin the pathway. In addition, we demonstrated,that autophagyactivation was calcium dependient, since this was hampered by the intracellular calciumchelator BAPTA-AM. Interestingly, the toxin effect was not prevented by the clasical autophagin inhibitor 3-MA and wortmannin, suggestin that the action of alpha hemolisin in independent of PI3K.