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- Title
Caenorhabditis elegans PI3K mutants reveal novel genes underlying exceptional stress resistance and lifespan.
- Authors
Ayyadevara, Srinivas; Tazearslan, Çagdaþ; Bharill, Puneet; Alla, Ramani; Siegel, Eric; Reis, Robert J. Shmookler
- 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.
- Subjects
CAENORHABDITIS elegans; PROTEIN kinases; DNA microarrays; PROTEIN microarrays; GENETIC transcription
- Publication
Aging Cell, 2009, Vol 8, Issue 6, p706
- ISSN
1474-9718
- Publication type
Article
- DOI
10.1111/j.1474-9726.2009.00524.x