title: Autophagy initiation by ULK complex assembly on ER tubulovesicular regions marked by ATG9 vesicles.
abstract: Autophagosome formation requires sequential translocation of autophagy-specific proteins to membranes enriched in PI3P and connected to the ER. Preceding this, the earliest autophagy-specific structure forming de novo is a small punctum of the ULK1 complex. The provenance of this structure and its mode of formation are unknown. We show that the ULK1 structure emerges from regions, where ATG9 vesicles align with the ER and its formation requires ER exit and coatomer function. Super-resolution microscopy reveals that the ULK1 compartment consists of regularly assembled punctate elements that cluster in progressively larger spherical structures and associates uniquely with the early autophagy machinery. Correlative electron microscopy after live imaging shows tubulovesicular membranes present at the locus of this structure. We propose that the nucleation of autophagosomes occurs in regions, where the ULK1 complex coalesces with ER and the ATG9 compartment.
authors: Signalling Programme, The Babraham Institute, Cambridge CB22 3AT, UK.
authors: Eleftherios
authors: E
authors: Karanasios
authors: Signalling Programme, The Babraham Institute, Cambridge CB22 3AT, UK.
authors: Simon A
authors: SA
authors: Walker
authors: Signalling Programme, The Babraham Institute, Cambridge CB22 3AT, UK.
authors: Hanneke
authors: H
authors: Okkenhaug
authors: Signalling Programme, The Babraham Institute, Cambridge CB22 3AT, UK.
authors: Maria
authors: M
authors: Manifava
authors: Carl Zeiss Microscopy GmbH, Munich 81379, Germany.
authors: Eric
authors: E
authors: Hummel
authors: Carl Zeiss Microscopy GmbH, Munich 81379, Germany.
authors: Hans
authors: H
authors: Zimmermann
authors: Signalling Programme, The Babraham Institute, Cambridge CB22 3AT, UK.
authors: Qashif
authors: Q
authors: Ahmed
authors: The Francis Crick Institute, London NW1 1AT, UK.
authors: Marie-Charlotte
authors: MC
authors: Domart
authors: The Francis Crick Institute, London NW1 1AT, UK.
authors: Lucy
authors: L
authors: Collinson
authors: Signalling Programme, The Babraham Institute, Cambridge CB22 3AT, UK.
authors: Nicholas T
authors: NT
authors: Ktistakis
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000071182:Autophagosomes / Q000378:metabolism; D001343:Autophagy; D000071189:Autophagy-Related Protein-1 Homolog / Q000378:metabolism*; D000071183:Autophagy-Related Proteins / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008928:Mitochondria / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D021381:Protein Transport; D033921:Vesicular Transport Proteins / Q000378:metabolism*
chemical_list: C534291:ATG13 protein, human; D048868:Adaptor Proteins, Signal Transducing; C574794:ATG9A protein, human; D000071183:Autophagy-Related Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D033921:Vesicular Transport Proteins; D049452:Green Fluorescent Proteins; D000071189:Autophagy-Related Protein-1 Homolog; C484754:ULK1 protein, human