title: p62 Targeting to the autophagosome formation site requires self-oligomerization but not LC3 binding.
abstract: Autophagy is an intracellular degradation process by which cytoplasmic contents are degraded in the lysosome. In addition to nonselective engulfment of cytoplasmic materials, the autophagosomal membrane can selectively recognize specific proteins and organelles. It is generally believed that the major selective substrate (or cargo receptor) p62 is recruited to the autophagosomal membrane through interaction with LC3. In this study, we analyzed loading of p62 and its related protein NBR1 and found that they localize to the endoplasmic reticulum (ER)-associated autophagosome formation site independently of LC3 localization to membranes. p62 colocalizes with upstream autophagy factors such as ULK1 and VMP1 even when autophagosome formation is blocked by wortmannin or FIP200 knockout. Self-oligomerization of p62 is essential for its localization to the autophagosome formation site. These results suggest that p62 localizes to the autophagosome formation site on the ER, where autophagosomes are nucleated. This process is similar to the yeast cytoplasm to vacuole targeting pathway.
authors.affiliation: Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan.
authors.forename: Eisuke
authors.initials: E
authors.lastname: Itakura
authors.forename: Noboru
authors.initials: N
authors.lastname: Mizushima
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000378:metabolism*; D000818:Animals; D001343:Autophagy; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D041681:NIH 3T3 Cells; D010588:Phagosomes / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000378:metabolism; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011506:Proteins / Q000378:metabolism; D000071456:Sequestosome-1 Protein; D013329:Structure-Activity Relationship
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D006360:Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins; C549756:NBR1 protein, human; D010714:Phosphatidylethanolamines; D011506:Proteins; D000071456:Sequestosome-1 Protein; C101343:Sqstm1 protein, mouse; C483858:phosphatidylethanolamine