Identification of a phosphorylation site on Ulk1 required for genotoxic stress-induced alternative autophagy

• Published in: Nature communications 2020-04, Vol.11 (1), p.1754-1754, Article 1754
• Main Authors: Torii, Satoru, Yamaguchi, Hirofumi, Nakanishi, Akira, Arakawa, Satoko, Honda, Shinya, Moriwaki, Kenta, Nakano, Hiroyasu, Shimizu, Shigeomi
• Format: Article
• Language: English
• Subjects: 14; 14/19; 14/28; 631/337; 631/80; 82/29; 82/51; 96/95; Amino Acid Sequence; Animals; Autophagy; Autophagy - genetics; Autophagy - physiology; Autophagy-Related Protein-1 Homolog - genetics; Autophagy-Related Protein-1 Homolog - metabolism; Binding Sites - genetics; Cells, Cultured; DNA Damage; Embryo, Mammalian - cytology; Etoposide - pharmacology; Fibroblasts - cytology; Fibroblasts - drug effects; Fibroblasts - metabolism; Genotoxicity; Golgi apparatus; Golgi Apparatus - metabolism; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Humanities and Social Sciences; Kinases; Mice, Knockout; Microscopy, Confocal; multidisciplinary; Phagocytosis; Phosphorylation; Protein kinase; Proteins; Receptor-Interacting Protein Serine-Threonine Kinases - genetics; Receptor-Interacting Protein Serine-Threonine Kinases - metabolism; Science; Science (multidisciplinary); Sequence Homology, Amino Acid; Serine - genetics; Serine - metabolism; Stress
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-15577-2

Alternative autophagy is an autophagy-related protein 5 (Atg5)-independent type of macroautophagy. Unc51-like kinase 1 (Ulk1) is an essential initiator not only for Atg5-dependent canonical autophagy but also for alternative autophagy. However, the mechanism as to how Ulk1 differentially regulates both types of autophagy has remained unclear. In this study, we identify a phosphorylation site of Ulk1 at Ser 746 , which is phosphorylated during genotoxic stress-induced alternative autophagy. Phospho-Ulk1 746 localizes exclusively on the Golgi and is required for alternative autophagy, but not canonical autophagy. We also identify receptor-interacting protein kinase 3 (RIPK3) as the kinase responsible for genotoxic stress-induced Ulk1 746 phosphorylation, because RIPK3 interacts with and phosphorylates Ulk1 at Ser 746 , and loss of RIPK3 abolishes Ulk1 746 phosphorylation. These findings indicate that RIPK3-dependent Ulk1 746 phosphorylation on the Golgi plays a pivotal role in genotoxic stress-induced alternative autophagy. Unlike canonical macroautophagy, alternative autophagy does not require the factors Atg5 and Atg7, but does require Ulk1. Here the authors show that phosphorylation of Ulk1 at Ser 746 by RIPK3 is required for alternative autophagy initiation at the Golgi in response to genotoxic stress.