Tsc tumour suppressor proteins antagonize amino-acid-TOR signalling

Nat Cell Biol. 2002 Sep;4(9):699-704. doi: 10.1038/ncb847.

Abstract

Target of Rapamycin (TOR) mediates a signalling pathway that couples amino acid availability to S6 kinase (S6K) activation, translational initiation and cell growth. Here, we show that tuberous sclerosis 1 (Tsc1) and Tsc2, tumour suppressors that are responsible for the tuberous sclerosis syndrome, antagonize this amino acid-TOR signalling pathway. We show that Tsc1 and Tsc2 can physically associate with TOR and function upstream of TOR genetically. In Drosophila melanogaster and mammalian cells, loss of Tsc1 and Tsc2 results in a TOR-dependent increase of S6K activity. Furthermore, although S6K is normally inactivated in animal cells in response to amino acid starvation, loss of Tsc1-Tsc2 renders cells resistant to amino acid starvation. We propose that the Tsc1-Tsc2 complex antagonizes the TOR-mediated response to amino acid availability. Our studies identify Tsc1 and Tsc2 as regulators of the amino acid-TOR pathway and provide a new paradigm for how proteins involved in nutrient sensing function as tumour suppressors.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acids / metabolism*
  • Animals
  • Cell Line
  • Drosophila Proteins*
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / growth & development
  • Drosophila melanogaster / metabolism
  • Genes, Insect
  • Genes, Tumor Suppressor
  • Humans
  • Insect Proteins / genetics
  • Insect Proteins / metabolism*
  • Mutation
  • Phosphatidylinositol 3-Kinases*
  • Phosphotransferases (Alcohol Group Acceptor) / genetics
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism*
  • Protein Kinases / genetics
  • Protein Kinases / metabolism
  • Proteins / genetics
  • Proteins / metabolism*
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Ribosomal Protein S6 Kinases / metabolism
  • Signal Transduction
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases
  • Tuberous Sclerosis Complex 1 Protein
  • Tuberous Sclerosis Complex 2 Protein
  • Tumor Suppressor Proteins

Substances

  • Amino Acids
  • Drosophila Proteins
  • Insect Proteins
  • Proteins
  • Repressor Proteins
  • TSC1 protein, human
  • TSC2 protein, human
  • Tuberous Sclerosis Complex 1 Protein
  • Tuberous Sclerosis Complex 2 Protein
  • Tumor Suppressor Proteins
  • Protein Kinases
  • Phosphatidylinositol 3-Kinases
  • Phosphotransferases (Alcohol Group Acceptor)
  • target of rapamycin protein, Drosophila
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • Ribosomal Protein S6 Kinases
  • Sirolimus