Article

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

Instituto de Histología y Embriología (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza 5500, Argentina.
Traffic (impact factor: 4.92). 09/2010; 11(9):1246-61. DOI:10.1111/j.1600-0854.2010.01086.x
Source: PubMed

ABSTRACT Autophagy is an important cellular degradation pathway present in all eukaryotic cells. Via this pathway, portions of the cytoplasm and/or organelles are sequestered in double-membrane structures called autophagosomes. In spite of the significant advance achieved in autophagy, the long-standing question about the source of the autophagic membrane remains unsolved. We have investigated the role of the secretory pathway in autophagosome biogenesis. Sar1 and Rab1b are monomeric GTPases that control traffic from the endoplasmic reticulum (ER) to the Golgi. We present evidence indicating that the activity of both proteins is required for autophagosome formation. Overexpression of dominant-negative mutants and the use of siRNAs impaired autophagosome generation as determined by LC3 puncta formation and light chain 3 (LC3)-II processing. In addition, our results indicate that the autophagic and secretory pathways intersect at a level preceding the brefeldin A blockage, suggesting that the transport from the cis/medial Golgi is not necessary for autophagosome biogenesis. Our present results highlight the role of transport from the ER in the initial events of the autophagic vacuole development.

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Keywords

autophagic membrane
 
autophagic vacuole development
 
autophagosome biogenesis
 
autophagosome formation
 
autophagosome generation
 
cellular degradation pathway present
 
cis/medial Golgi
 
control traffic
 
dominant-negative mutants
 
double-membrane structures
 
eukaryotic cells
 
LC3 puncta formation
 
LC3)-II processing
 
light chain 3
 
long-standing question
 
present results
 
secretory pathway
 
secretory pathways intersect
 
significant advance
 
spite