Caenorhabditis elegans PI3K mutants reveal novel genes underlying exceptional stress resistance and lifespan

Srinivas Ayyadevara, Çagdth Tazearslan, Puneet Bharill, Ramani Alla, Eric Siegel, Robert J. Shmookler Reis

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

Two age-1 nonsense mutants, truncating the class-I phosphatidylinositol 3-kinase catalytic subunit (PI3KCS) before its kinase domain, confer extraordinary longevity and stress-resistance to Caenorhabditis elegans. These traits, unique to second-generation homozygotes, are blunted at the first generation and are largely reversed by additional mutations to DAF-16/FOXO, a transcription factor downstream of AGE-1 in insulin-like signaling. The strong age-1 alleles (mg44, m333) were compared with the weaker hx546 allele on expression microarrays, testing four independent cohorts of each allele. Among 276 genes with significantly differential expression, 92% showed fewer transcripts in adults carrying strong age-1 alleles rather than hx546. This proportion is significantly greater than the slight bias observed when contrasting age-1 alleles to wild-type worms. Thus, transcriptional changes peculiar to nonsense alleles primarily involve either gene silencing or failure of transcriptional activation. A subset of genes responding preferentially to age-1-nonsense alleles was reassessed by real-time polymerase chain reaction, in worms bearing strong or weak age-1 alleles; nearly all of these were significantly more responsive to the age-1(mg44) allele than to age-1(hx546). Additional mutation of daf-16 reverted the majority of altered mg44-F2 expression levels to approximately wild-type values, although a substantial number of genes remained significantly distinct from wild-type, implying that age-1(mg44) modulates transcription through both DAF-16/FOXO-dependent and-independent channels. When age-1-inhibited genes were targeted by RNA interference (RNAi) in wild-type or age-1(hx546) adults, most conferred significant oxidative-stress protection. RNAi constructs targeting two of those genes were shown previously to extend life, and RNAi's targeting five novel genes were found here to increase lifespan. PI3K-null mutants may thus implicate novel mechanisms of life extension.

Original languageEnglish (US)
Pages (from-to)706-725
Number of pages20
JournalAging cell
Volume8
Issue number6
DOIs
Publication statusPublished - Dec 1 2009

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Keywords

  • Aging
  • Caenorhabditis elegans
  • Dauer
  • Gene expression
  • Life-span
  • Lifespan
  • Longevity
  • Stress resistance

ASJC Scopus subject areas

  • Aging
  • Cell Biology

Cite this

Ayyadevara, S., Tazearslan, Ç., Bharill, P., Alla, R., Siegel, E., & Shmookler Reis, R. J. (2009). Caenorhabditis elegans PI3K mutants reveal novel genes underlying exceptional stress resistance and lifespan. Aging cell, 8(6), 706-725. https://doi.org/10.1111/j.1474-9726.2009.00524.x