Inhibition of mTOR induces autophagy and reduces toxicity of polyglutamine expansions in fly and mouse models of Huntington disease

Nat Genet. 2004 Jun;36(6):585-95. doi: 10.1038/ng1362. Epub 2004 May 16.

Abstract

Huntington disease is one of nine inherited neurodegenerative disorders caused by a polyglutamine tract expansion. Expanded polyglutamine proteins accumulate abnormally in intracellular aggregates. Here we show that mammalian target of rapamycin (mTOR) is sequestered in polyglutamine aggregates in cell models, transgenic mice and human brains. Sequestration of mTOR impairs its kinase activity and induces autophagy, a key clearance pathway for mutant huntingtin fragments. This protects against polyglutamine toxicity, as the specific mTOR inhibitor rapamycin attenuates huntingtin accumulation and cell death in cell models of Huntington disease, and inhibition of autophagy has the converse effects. Furthermore, rapamycin protects against neurodegeneration in a fly model of Huntington disease, and the rapamycin analog CCI-779 improved performance on four different behavioral tasks and decreased aggregate formation in a mouse model of Huntington disease. Our data provide proof-of-principle for the potential of inducing autophagy to treat Huntington disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagy
  • COS Cells
  • Disease Models, Animal
  • Drosophila melanogaster
  • Female
  • Humans
  • Huntingtin Protein
  • Huntington Disease / drug therapy*
  • Huntington Disease / genetics
  • Huntington Disease / metabolism
  • Macromolecular Substances
  • Male
  • Mice
  • Mice, Transgenic
  • Mutation
  • Nerve Tissue Proteins / chemistry
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Peptides / chemistry
  • Peptides / genetics
  • Peptides / metabolism
  • Protein Biosynthesis
  • Protein Kinase Inhibitors*
  • Protein Kinases / metabolism
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases

Substances

  • HTT protein, human
  • Htt protein, mouse
  • Huntingtin Protein
  • Macromolecular Substances
  • Nerve Tissue Proteins
  • Nuclear Proteins
  • Peptides
  • Protein Kinase Inhibitors
  • polyglutamine
  • Protein Kinases
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • mTOR protein, mouse
  • Sirolimus