Autophagosome formation depends on the small GTPase Rab1 and functiona ER exit sites

ZOPPINO FCM; MILITELLO RD; SLAVIN I; ALVAREZ C Y COLOMBO MI

Tucumán, Argentina

Congreso; XLV Reunión anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

SAIB

Autophagy is an important cellular component degradation pathway present in all eukaryotic cells. Autophagy sequesters portions of cytoplasm and/or organelles in emerging double membrane structures call autophagosomes. In spite of the intense advance achieved in the autophagy´s knowledge little information exists with regard to the formation of the autophagosomes in the mammalian cells. The present work is based on the investigation of the secretory pathway, principally on its early stage, as key route involved in the autophagosome formation. Sar1 and Rab1b are monomeric GTPases that control the anterograde traffic from the Endoplasmic Reticulum to the Golgi apparatus. The analysis of autophagic pathway was realized by the monitoring of LC3, a well known marker of autophagosome, by confocal microscopy and western blot. We demonstrate for the first time the requirement of the Sar1 and Rab1b for the autophagosome formation in mammalian cells and determine that the autophagy and secretory pathway cross at level of the stage controlled for Rab1b. Also by means of the blockage of the action of Arf1, we verify that the transport from the cis/medial Golgi is not necessary for the formation of the autophagosomas