The Actin Cytoskeleton and a RhoA Controlled Pathway Participated in Starvation Mediated Autophagy

AGUILERA, MO; BERÓN, W ; COLOMBO, MI

Mendoza

Congreso; XLVIII Reunión Nacional de la Sociedad Argentina de Investigaciones Bioquímica y Biología Molecular (SAIB).; 2012

Autophagy is process in which a double membrane vesicle sequesters cytoplasmic material destined to degradation. In cells exists a basal level of autophagy that could be enhanced by different stimulus. Initially, autophagosome formation requires membrane remodeling to generate a vesicle which subsequently matures in a process that involves fusion with other compartments. In the current work we have demonstrated that actin is necessary for starvationmediated autophagy. When the actin cytoskeleton was depolymerized, the increase in autophagic vacuoles in response to the starvation stimulus was abolished without affecting the maturation of the autophagosomes. Interestingly, actin filaments colocalized with Atg14, Beclin 1 and PtdIns3P-rich structures stained with the double FYVE domain or the protein DFCP1. In addition, we have found that a RhoA-controled pathway has a regulatory function on starvation-mediated autophagy. Overexpression of RhoAmutants or depletion of the protein, as well as inhibition of some downstream effectors, hampered starvationmediated autophagy. Also, similar to actin, RhoA colocalized with Beclin1 suggesting that both protein are involved in the same stage. Taken together, our data indicate that the actin cytoskeleton and the RhoA and its effectors, have a key role at very early stages of autophagosome formation linked to the PtdIns3P generation step.