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Novel targets for Huntington's disease in an mTOR-independent autophagy pathway

Andrea Williams1, Sovan Sarkar, Paul Cuddon

  • 1Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK.

Nature Chemical Biology
|April 9, 2008
PubMed

Insights

Researchers identified new drugs that induce autophagy, a cellular process crucial for clearing toxic proteins in diseases like Huntington's. This discovery offers potential therapeutic strategies beyond rapamycin, targeting a novel pathway to enhance cellular cleanup mechanisms.

Area of Science:

  • Cellular Biology
  • Neuroscience
  • Pharmacology

Background:

  • Autophagy is a key cellular mechanism for clearing toxic, aggregate-prone proteins implicated in neurodegenerative diseases such as Huntington's disease.
  • Rapamycin, an mTOR inhibitor, can induce autophagy to clear these proteins but has significant side effects.
  • There is a need for alternative therapeutic strategies that can safely induce autophagy.

Purpose of the Study:

  • To screen FDA-approved drugs for novel autophagy-inducing pathways independent of mTOR inhibition.
  • To elucidate a new, cyclical, mTOR-independent pathway regulating autophagy.
  • To explore the therapeutic potential of identified autophagy inducers for Huntington's disease.

Main Methods:

  • Screening of FDA-approved drugs to identify compounds that induce autophagy.
  • Utilizing mammalian cell, fly, and zebrafish models to validate findings.
  • Investigating a novel cAMP-mediated pathway involving IP3, calpain, and G(s)alpha.

Main Results:

  • L-type Ca2+ channel antagonists, minoxidil, and clonidine were identified as autophagy inducers.
  • A novel, cyclical, mTOR-independent autophagy pathway was characterized, regulated by cAMP, IP3, calpain, and G(s)alpha.
  • Therapeutic relevance was demonstrated in cellular, fly, and zebrafish models of Huntington's disease.
  • Elevated intracellular Ca2+ was found to inhibit autophagy, hindering toxic protein clearance.

Conclusions:

  • FDA-approved drugs can be repurposed to induce autophagy via novel pathways.
  • The identified mTOR-independent pathway offers new therapeutic targets for diseases characterized by toxic protein aggregation.
  • Understanding the interplay between Ca2+ and autophagy is critical for neurodegenerative disease treatment.

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