Direct inhibition of the longevity-promoting factor SKN-1 by insulin-like signaling in C. elegans

Cell. 2008 Mar 21;132(6):1025-38. doi: 10.1016/j.cell.2008.01.030.

Abstract

Insulin/IGF-1-like signaling (IIS) is central to growth and metabolism and has a conserved role in aging. In C. elegans, reductions in IIS increase stress resistance and longevity, effects that require the IIS-inhibited FOXO protein DAF-16. The C. elegans transcription factor SKN-1 also defends against oxidative stress by mobilizing the conserved phase 2 detoxification response. Here we show that IIS not only opposes DAF-16 but also directly inhibits SKN-1 in parallel. The IIS kinases AKT-1, -2, and SGK-1 phosphorylate SKN-1, and reduced IIS leads to constitutive SKN-1 nuclear accumulation in the intestine and SKN-1 target gene activation. SKN-1 contributes to the increased stress tolerance and longevity resulting from reduced IIS and delays aging when expressed transgenically. Furthermore, SKN-1 that is constitutively active increases life span independently of DAF-16. Our findings indicate that the transcription network regulated by SKN-1 promotes longevity and is an important direct target of IIS.

Publication types

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

MeSH terms

  • Animals
  • Caenorhabditis elegans / physiology*
  • Caenorhabditis elegans Proteins / metabolism*
  • DNA-Binding Proteins / metabolism*
  • Gene Regulatory Networks
  • Insulin / metabolism
  • Insulin-Like Growth Factor I / metabolism
  • Intestines
  • Longevity
  • Oxidative Stress
  • Phosphorylation
  • Receptor, Insulin / metabolism
  • Signal Transduction*
  • Transcription Factors / metabolism*

Substances

  • Caenorhabditis elegans Proteins
  • DNA-Binding Proteins
  • Insulin
  • Transcription Factors
  • skn-1 protein, C elegans
  • Insulin-Like Growth Factor I
  • DAF-2 protein, C elegans
  • Receptor, Insulin