The association of AMPK with ULK1 regulates autophagy

PLoS One. 2010 Nov 3;5(11):e15394. doi: 10.1371/journal.pone.0015394.

Abstract

Autophagy is a highly orchestrated intracellular bulk degradation process that is activated by various environmental stresses. The serine/threonine kinase ULK1, like its yeast homologue Atg1, is a key initiator of autophagy that is negatively regulated by the mTOR kinase. However, the molecular mechanism that controls the inhibitory effect of mTOR on ULK1-mediated autophagy is not fully understood. Here we identified AMPK, a central energy sensor, as a new ULK1-binding partner. We found that AMPK binds to the PS domain of ULK1 and this interaction is required for ULK1-mediated autophagy. Interestingly, activation of AMPK by AICAR induces 14-3-3 binding to the AMPK-ULK1-mTORC1 complex, which coincides with raptor Ser792 phosphorylation and mTOR inactivation. Consistently, AICAR induces autophagy in TSC2-deficient cells expressing wild-type raptor but not the mutant raptor that lacks the AMPK phosphorylation sites (Ser722 and Ser792). Taken together, these results suggest that AMPK association with ULK1 plays an important role in autophagy induction, at least in part, by phosphorylation of raptor to lift the inhibitory effect of mTOR on the ULK1 autophagic complex.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 14-3-3 Proteins / genetics
  • 14-3-3 Proteins / metabolism
  • AMP-Activated Protein Kinases / genetics
  • AMP-Activated Protein Kinases / metabolism*
  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism
  • Animals
  • Autophagy*
  • Autophagy-Related Protein-1 Homolog
  • Binding Sites
  • Cell Line
  • Cell Line, Tumor
  • Cells, Cultured
  • HEK293 Cells
  • Humans
  • Immunoblotting
  • Immunoprecipitation
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Mechanistic Target of Rapamycin Complex 1
  • Mice
  • Mice, Knockout
  • Microscopy, Fluorescence
  • Multiprotein Complexes
  • Mutation
  • Phosphorylation
  • Protein Binding
  • Protein Subunits / genetics
  • Protein Subunits / metabolism
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proteins / genetics
  • Proteins / metabolism
  • RNA Interference
  • Regulatory-Associated Protein of mTOR
  • TOR Serine-Threonine Kinases
  • Transfection

Substances

  • 14-3-3 Proteins
  • Adaptor Proteins, Signal Transducing
  • Intracellular Signaling Peptides and Proteins
  • Multiprotein Complexes
  • Protein Subunits
  • Proteins
  • RPTOR protein, human
  • Regulatory-Associated Protein of mTOR
  • TOR Serine-Threonine Kinases
  • Autophagy-Related Protein-1 Homolog
  • Mechanistic Target of Rapamycin Complex 1
  • PRKAA2 protein, human
  • Protein-Serine-Threonine Kinases
  • ULK1 protein, human
  • AMP-Activated Protein Kinases