Mycobacterium marinum interacts with LC3 and benefits from autophagy induction.

LERENA, C.; COLOMBO, M. I.

Tucumán, Argentina

Congreso; SAIB; 2009

MYCOBACTERIUM MARINUM INTERACTS WITH LC3 AND BENEFITS FROM AUTOPHAGY INDUCTION Lerena MC, Colombo MI. Lab. de Biol. Celular y Molecular, IHEM-CONICET, F.C.M. U.N. Cuyo, Mendoza, Argentina. clerena@fcm.uncu.edu.ar Mycobacterium marinum; a natural pathogen of frogs and fishes; can eventually infect humans, and has been extensively used as a model to study pathogenic mycobacteria. We have studied the interplay of M. marinum and the autophagic pathway. For this purpose we have used macrophages overexpressing GFP-LC3, a marker for double membrane autophagosomes. We have previously observed that M. marinum resides within an LC3 positive compartment, and this association depends on the bacterial viability. We have also characterized the LC3-positive compartment containing M. marinum, which shows features of late endosomes such as Rab7 and LAMP2. However, this phagosome does not acquire the lysosomal marker cathepsin D, nor DQ-BSA labeling, suggesting it is not a degradative compartment.  By electron microscopy, we have shown that early after infection (1 to 2 hours) M. marinum resides mostly in single membrane compartments, in spite of the presence of LC3 on their membranes; and also that a subset of the infecting bacteria are free in the cytosol at 2 hours post infection. Finally, M. marinum survival within the cell appears to benefit upon autophagy induction with starvation medium. All these data suggest a complex interplay of M. marinum with autophagy, where M.marinum modulates its LC3 positive compartment, and benefits from autophagy induction.