title: The ULK1 complex mediates MTORC1 signaling to the autophagy initiation machinery via binding and phosphorylating ATG14.
abstract: ULK1 (unc-51 like autophagy activating kinase 1), the key mediator of MTORC1 signaling to autophagy, regulates early stages of autophagosome formation in response to starvation or MTORC1 inhibition. How ULK1 regulates the autophagy induction process remains elusive. Here, we identify that ATG13, a binding partner of ULK1, mediates interaction of ULK1 with the ATG14-containing PIK3C3/VPS34 complex, the key machinery for initiation of autophagosome formation. The interaction enables ULK1 to phosphorylate ATG14 in a manner dependent upon autophagy inducing conditions, such as nutrient starvation or MTORC1 inhibition. The ATG14 phosphorylation mimics nutrient deprivation through stimulating the kinase activity of the class III phosphatidylinositol 3-kinase (PtdIns3K) complex and facilitates phagophore and autophagosome formation. By monitoring the ATG14 phosphorylation, we determined that the ULK1 activity requires BECN1/Beclin 1 but not the phosphatidylethanolamine (PE)-conjugation machinery and the PIK3C3 kinase activity. Monitoring the phosphorylation also allowed us to identify that ATG9A is required to suppress the ULK1 activity under nutrient-enriched conditions. Furthermore, we determined that ATG14 phosphorylation depends on ULK1 and dietary conditions in vivo. These results define a key molecular event for the starvation-induced activation of the ATG14-containing PtdIns3K complex by ULK1, and demonstrate hierarchical relations between the ULK1 activation and other autophagy proteins involved in phagophore formation.
authors.affiliation: a Department of Biochemistry, Molecular Biology, and Biophysics , University of Minnesota , Minneapolis , MN , USA.
authors.forename: Ji-Man
authors.initials: JM
authors.lastname: Park
authors.affiliation: a Department of Biochemistry, Molecular Biology, and Biophysics , University of Minnesota , Minneapolis , MN , USA.|b Division of Metabolism and Functionality Research, Korea Food Research Institute , Sungnam, Gyeonggi-do , Republic of Korea.
authors.forename: Chang Hwa
authors.initials: CH
authors.lastname: Jung
authors.affiliation: a Department of Biochemistry, Molecular Biology, and Biophysics , University of Minnesota , Minneapolis , MN , USA.
authors.forename: Minchul
authors.initials: M
authors.lastname: Seo
authors.affiliation: a Department of Biochemistry, Molecular Biology, and Biophysics , University of Minnesota , Minneapolis , MN , USA.
authors.forename: Neil Michael
authors.initials: NM
authors.lastname: Otto
authors.affiliation: a Department of Biochemistry, Molecular Biology, and Biophysics , University of Minnesota , Minneapolis , MN , USA.
authors.forename: Douglas
authors.initials: D
authors.lastname: Grunwald
authors.affiliation: a Department of Biochemistry, Molecular Biology, and Biophysics , University of Minnesota , Minneapolis , MN , USA.
authors.forename: Kwan Hyun
authors.initials: KH
authors.lastname: Kim
authors.affiliation: c Department of Pediatrics , University of Minnesota , Minneapolis , MN , USA.|d Masonic Cancer Center, University of Minnesota , Minneapolis , MN , USA.
authors.forename: Branden
authors.initials: B
authors.lastname: Moriarity
authors.affiliation: a Department of Biochemistry, Molecular Biology, and Biophysics , University of Minnesota , Minneapolis , MN , USA.
authors.forename: Young-Mi
authors.initials: YM
authors.lastname: Kim
authors.affiliation: e Department of Genetics, Cell Biology, and Development , University of Minnesota , Minneapolis , MN , USA.|f Center for Genome Engineering, University of Minnesota , Minneapolis , MN , USA.
authors.forename: Colby
authors.initials: C
authors.lastname: Starker
authors.affiliation: d Masonic Cancer Center, University of Minnesota , Minneapolis , MN , USA.|g Department of Medicine , University of Minnesota , Minneapolis , MN , USA.
authors.forename: Richard Seonghun
authors.initials: RS
authors.lastname: Nho
authors.affiliation: e Department of Genetics, Cell Biology, and Development , University of Minnesota , Minneapolis , MN , USA.|f Center for Genome Engineering, University of Minnesota , Minneapolis , MN , USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Voytas
authors.affiliation: a Department of Biochemistry, Molecular Biology, and Biophysics , University of Minnesota , Minneapolis , MN , USA.|d Masonic Cancer Center, University of Minnesota , Minneapolis , MN , USA.
authors.forename: Do-Hyung
authors.initials: DH
authors.lastname: Kim
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000378:metabolism; D033942:Adaptor Proteins, Vesicular Transport / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D000071182:Autophagosomes / Q000378:metabolism; D001343:Autophagy; D000071189:Autophagy-Related Protein-1 Homolog / Q000378:metabolism*; D000071183:Autophagy-Related Proteins / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D058534:Class I Phosphatidylinositol 3-Kinases / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D046912:Multiprotein Complexes / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011485:Protein Binding; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D015854:Up-Regulation; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: C534291:ATG13 protein, human; C539000:ATG14 protein, human; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; C561107:Atg14 protein, mouse; D000071183:Autophagy-Related Proteins; D047908:Intracellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; D010714:Phosphatidylethanolamines; D033921:Vesicular Transport Proteins; D010768:Phosphoserine; C483858:phosphatidylethanolamine; D058534:Class I Phosphatidylinositol 3-Kinases; D000071189:Autophagy-Related Protein-1 Homolog; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; C484754:ULK1 protein, human; C112444:Ulk1 protein, mouse
keywords: ATG13; ATG14; BECN1; MTORC1; PIK3C3; ULK1