The E3 ubiquitin ligase ZNRF2 is a substrate of mTORC1 and regulates its activation by amino acids

Elife. 2016 Apr 22;5:e12278. doi: 10.7554/eLife.12278.

Abstract

The mechanistic Target of Rapamycin complex 1 (mTORC1) senses intracellular amino acid levels through an intricate machinery, which includes the Rag GTPases, Ragulator and vacuolar ATPase (V-ATPase). The membrane-associated E3 ubiquitin ligase ZNRF2 is released into the cytosol upon its phosphorylation by Akt. In this study, we show that ZNRF2 interacts with mTOR on membranes, promoting the amino acid-stimulated translocation of mTORC1 to lysosomes and its activation in human cells. ZNRF2 also interacts with the V-ATPase and preserves lysosomal acidity. Moreover, knockdown of ZNRF2 decreases cell size and cell proliferation. Upon growth factor and amino acid stimulation, mTORC1 phosphorylates ZNRF2 on Ser145, and this phosphosite is dephosphorylated by protein phosphatase 6. Ser145 phosphorylation stimulates vesicle-to-cytosol translocation of ZNRF2 and forms a novel negative feedback on mTORC1. Our findings uncover ZNRF2 as a component of the amino acid sensing machinery that acts upstream of Rag-GTPases and the V-ATPase to activate mTORC1.

Keywords: PP6; Ragulator; V-ATPase; ZNRF2; amino acid sensing; biochemistry; cell biology; human; mTORC1; mouse.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / metabolism*
  • GTP Phosphohydrolases / metabolism
  • Gene Expression Regulation, Enzymologic*
  • Gene Knockdown Techniques
  • Humans
  • Mechanistic Target of Rapamycin Complex 1
  • Multiprotein Complexes / metabolism*
  • Protein Interaction Mapping
  • TOR Serine-Threonine Kinases / metabolism*
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*
  • Vacuolar Proton-Translocating ATPases / metabolism

Substances

  • Amino Acids
  • Multiprotein Complexes
  • Ubiquitin-Protein Ligases
  • ZNRF2 protein, human
  • TOR Serine-Threonine Kinases
  • Mechanistic Target of Rapamycin Complex 1
  • GTP Phosphohydrolases
  • Vacuolar Proton-Translocating ATPases