Mutagenesis screen uncovers lifespan extension through integrated stress response inhibition without reduced mRNA translation

Protein homeostasis is modulated by stress response pathways and its deficiency is a hallmark of aging. The integrated stress response (ISR) is a conserved stress-signaling pathway that tunes mRNA translation via phosphorylation of the translation initiation factor eIF2. ISR activation and translation initiation are finely balanced by eIF2 kinases and by the eIF2 guanine nucleotide exchange factor eIF2B. However, the role of the ISR during aging remains poorly understood. Using a genomic mutagenesis screen for longevity in Caenorhabditis elegans, we define a role of eIF2 modulation in aging. By inhibiting the ISR, dominant mutations in eIF2B enhance protein homeostasis and increase lifespan. Consistently, full ISR inhibition using phosphorylation-defective eIF2 alpha or pharmacological ISR inhibition prolong lifespan. Lifespan extension through impeding the ISR occurs without a reduction in overall protein synthesis. Instead, we observe changes in the translational efficiency of a subset of mRNAs, of which the putative kinase kin-35 is required for lifespan extension. Evidently, lifespan is limited by the ISR and its inhibition may provide an intervention in aging. Aging is associated with declining protein homeostasis. Here, using a chemical mutagenesis screen for lifespan extension in C. elegans, the authors report that inhibition of the integrated stress response enhances longevity and protein homeostasis in a manner dependent on kin-35, without reducing protein synthesis.

Automated summary

Protein homeostasis is regulated by stress response pathways, and its deficiency is a sign of aging. The integrated stress response (ISR) pathway plays a role in modulating mRNA translation, and inhibiting ISR through mutations in eIF2B or pharmacological interventions can extend lifespan without reducing overall protein synthesis.