title: Endoplasmic reticulum stress triggers autophagy.
abstract: Eukaryotic cells have evolved strategies to respond to stress conditions. For example, autophagy in yeast is primarily a response to the stress of nutrient limitation. Autophagy is a catabolic process for the degradation and recycling of cytosolic, long lived, or aggregated proteins and excess or defective organelles. In this study, we demonstrate a new pathway for the induction of autophagy. In the endoplasmic reticulum (ER), accumulation of misfolded proteins causes stress and activates the unfolded protein response to induce the expression of chaperones and proteins involved in the recovery process. ER stress stimulated the assembly of the pre-autophagosomal structure. In addition, autophagosome formation and transport to the vacuole were stimulated in an Atg protein-dependent manner. Finally, Atg1 kinase activity reflects both the nutritional status and autophagic state of the cell; starvation-induced autophagy results in increased Atg1 kinase activity. We found that Atg1 had high kinase activity during ER stress-induced autophagy. Together, these results indicate that ER stress can induce an autophagic response.
authors.affiliation: Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Yorimitsu
authors.forename: Usha
authors.initials: U
authors.lastname: Nair
authors.forename: Zhifen
authors.initials: Z
authors.lastname: Yang
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Klionsky
mesh_terms: D001343:Autophagy / Q000187:drug effects / Q000502:physiology*; D000071190:Autophagy-Related Protein 8 Family; D004229:Dithiothreitol / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D010588:Phagosomes / Q000187:drug effects / Q000502:physiology; D017510:Protein Folding; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014415:Tunicamycin / Q000494:pharmacology
chemical_list: C113757:ATG8 protein, S cerevisiae; D000071190:Autophagy-Related Protein 8 Family; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins; D014415:Tunicamycin; D004229:Dithiothreitol