The autophagy initiating kinase ULK1 is regulated via opposing phosphorylation by AMPK and mTOR

Autophagy. 2011 Jun;7(6):643-4. doi: 10.4161/auto.7.6.15123. Epub 2011 Jun 1.

Abstract

The serine/threonine kinase ULK1 is a mammalian homolog of Atg1, part of the Atg1 kinase complex, which is the most upstream component of the core autophagy machinery conserved from yeast to mammals. In budding yeast, activity of the Atg1 kinase complex is inhibited by TORC1 (target of rapamycin complex 1), but how the counterpart ULK1 complex in mammalian cells is regulated has been unknown. Our laboratories recently discovered that AMPK associates with, and directly phosphorylates, ULK1 on several sites and this modification is required for ULK1 activation after glucose deprivation. In contrast, when nutrients are plentiful, the mTORC1 complex phosphorylates ULK1, preventing its association and activation by AMPK. These studies have revealed a molecular mechanism of ULK1 regulation by nutrient signals via the actions of AMPK and mTORC1.

MeSH terms

  • Adenylate Kinase / metabolism*
  • Animals
  • Autophagy / physiology*
  • Autophagy-Related Protein-1 Homolog
  • Caenorhabditis elegans
  • Gene Expression Regulation, Fungal*
  • Glucose / metabolism
  • Humans
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Mechanistic Target of Rapamycin Complex 1
  • Mice
  • Models, Biological
  • Multiprotein Complexes
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proteins / metabolism
  • Saccharomycetales
  • TOR Serine-Threonine Kinases / metabolism*

Substances

  • Intracellular Signaling Peptides and Proteins
  • Multiprotein Complexes
  • Proteins
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • Autophagy-Related Protein-1 Homolog
  • Mechanistic Target of Rapamycin Complex 1
  • Protein-Serine-Threonine Kinases
  • ULK1 protein, human
  • Adenylate Kinase
  • Glucose