Formation and maturation of autophagosomes in higher eukaryotes: a social network.

Autophagy, a self-eating process conserved from yeast to mammals, is critical for maintaining cell homeostasis. It involves the formation of a double-membrane structure, called the autophagosome, and its subsequent delivery to lysosomes for degradation of sequestrated materials. Our knowledge about autophagy has greatly expanded over the last two decades, mainly due to studies of a set of autophagy-related (ATG) genes identified from yeast genetic screens. Autophagy in higher eukaryotes is far more complicated, because it involves steps that are not present in yeast. These include the formation of extensive contacts between the ER and the isolation membrane (IM, autophagosome precursor), and the maturation of nascent autophagosomes into degradative autolysosomes via fusion with vesicles generated from the endolysosomal compartment. Recent studies have discovered factors that act at these unique steps, greatly advancing our molecular understanding of autophagy in higher eukaryotes.