Autophagy induction extends lifespan and reduces lipid content in response to frataxin silencing in C. elegans

Exp Gerontol. 2013 Feb;48(2):191-201. doi: 10.1016/j.exger.2012.12.002. Epub 2012 Dec 13.

Abstract

Severe mitochondria deficiency leads to a number of devastating degenerative disorders, yet, mild mitochondrial dysfunction in different species, including the nematode Caenorhabditis elegans, can have pro-longevity effects. This apparent paradox indicates that cellular adaptation to partial mitochondrial stress can induce beneficial responses, but how this is achieved is largely unknown. Complete absence of frataxin, the mitochondrial protein defective in patients with Friedreich's ataxia, is lethal in C. elegans, while its partial deficiency extends animal lifespan in a p53 dependent manner. In this paper we provide further insight into frataxin control of C. elegans longevity by showing that a substantial reduction of frataxin protein expression is required to extend lifespan, affect sensory neurons functionality, remodel lipid metabolism and trigger autophagy. We find that Beclin and p53 genes are required to induce autophagy and concurrently reduce lipid storages and extend animal lifespan in response to frataxin suppression. Reciprocally, frataxin expression modulates autophagy in the absence of p53. Human Friedreich ataxia-derived lymphoblasts also display increased autophagy, indicating an evolutionarily conserved response to reduced frataxin expression. In sum, we demonstrate a causal connection between induction of autophagy and lifespan extension following reduced frataxin expression, thus providing the rationale for investigating autophagy in the pathogenesis and treatment of Friedreich's ataxia and possibly other human mitochondria-associated disorders.

Publication types

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

MeSH terms

  • AMP-Activated Protein Kinases / metabolism
  • Animals
  • Apoptosis Regulatory Proteins / metabolism
  • Autophagy*
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Friedreich Ataxia / genetics
  • Friedreich Ataxia / metabolism*
  • Friedreich Ataxia / pathology
  • Gene Silencing*
  • Humans
  • Iron-Binding Proteins / genetics
  • Iron-Binding Proteins / metabolism*
  • Lipid Metabolism*
  • Longevity*
  • Mitochondria / metabolism
  • RNA Interference
  • Sensory Receptor Cells / metabolism
  • Tumor Suppressor Protein p53 / metabolism

Substances

  • Apoptosis Regulatory Proteins
  • CEP-1 protein, C elegans
  • Caenorhabditis elegans Proteins
  • Iron-Binding Proteins
  • Tumor Suppressor Protein p53
  • frataxin
  • AMP-Activated Protein Kinases