POTENTIAL ROLE OF RAB21, RAB32 AND VARP IN THE AUTOPHAGIC EXOCYTOSIS

BARBOSA MC; GALLI T; COLOMBO MI.; FADER CM

Mar del Plata

Congreso; LI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2015

SAIB

Autophagy is a degradation process, being LC3 the main autophagosomal membrane protein. Rab32, a GTP-ase involved in the cellular transport, is related to autophagy. We described that some autophagosomes redistribute to the cell periphery and they also fuse with plasma membrane in a VAMP7 (a v-SNARE) dependent manner. This protein can interact with different proteins, like Rab21, its GEF (VARP) and Rab32. We found that Rab21 and LC3 colocalize at the cell periphery after autophagic activation. The aim of this work is to evaluate the role of Rab21, Rab32 and VARP in the redistribution of exocytic autophagosomes after autophagic stimulus. HeLa cells were transfected with GFP-Rab21 (wt or T33N), RFP-LC3 or YFP-Rab32 and then were incubated in starvation, rapamycin or resveratrol for 2-4 hours. We detected Golgi (GM130) or VARP proteins by immunofluorescence. We observed the presence of two populations of Rab32 vesicles: One is perinuclear and colocalizes with the Golgi marker; the other one colocalizes with VARP peripherically. We also found that upon autophagic stimulation, LC3- Rab32 or LC3-Rab21wt positive vesicles changed their distribution toward the periphery while Rab21 mutant still colocalizes with Golgi. Our result suggests that Rab32, Rab21 and VARP could be implicated in the autophagosomes? trafficking to the cell periphery, possibly favoring the autophagic exocytosis.