Abstract
Lowered activity of the insulin/IGF signalling (IIS) network can ameliorate the effects of ageing in laboratory animals and, possibly, humans. Although transcriptome remodelling in long‐lived IIS mutants has been extensively documented, the causal mechanisms contributing to extended lifespan, particularly in specific tissues, remain unclear. We have characterized the proteomes of four key insulin‐sensitive tissues in a long‐lived Drosophila IIS mutant and control, and detected 44% of the predicted proteome (6,085 proteins). Expression of ribosome‐associated proteins in the fat body was reduced in the mutant, with a corresponding, tissue‐specific reduction in translation. Expression of mitochondrial electron transport chain proteins in fat body was increased, leading to increased respiration, which was necessary for IIS‐mediated lifespan extension, and alone sufficient to mediate it. Proteasomal subunits showed altered expression in IIS mutant gut, and gut‐specific over‐expression of the RPN6 proteasomal subunit, was sufficient to increase proteasomal activity and extend lifespan, whilst inhibition of proteasome activity abolished IIS‐mediated longevity. Our study thus uncovered strikingly tissue‐specific responses of cellular processes to lowered IIS acting in concert to ameliorate ageing.
Highlights
Lowered activity of the insulin/IGF signalling (IIS) network can ameliorate the effects of ageing in laboratory animals and, possibly, humans
Gene ontology (GO) enrichment analysis showed that these served a variety of house-keeping functions, and included mitochondrial and ribosomal constituents
Mapping GO terms onto the proteins contributing to PC1 revealed that proteins with neuronal functions accounted for much of the effect, separating the brain, which had the largest number of unique proteins, from the other three tissues
Summary
Lowered activity of the insulin/IGF signalling (IIS) network can ameliorate the effects of ageing in laboratory animals and, possibly, humans. Transcriptome remodelling in long-lived IIS mutants has been extensively documented, the causal mechanisms contributing to extended lifespan, in specific tissues, remain unclear. We have characterized the proteomes of four key insulin-sensitive tissues in a long-lived Drosophila IIS mutant and control, and detected 44% of the predicted proteome (6,085 proteins). Expression of ribosome-associated proteins in the fat body was reduced in the mutant, with a corresponding, tissuespecific reduction in translation. Expression of mitochondrial electron transport chain proteins in fat body was increased, leading to increased respiration, which was necessary for IIS-mediated lifespan extension, and alone sufficient to mediate it. Our study uncovered strikingly tissue-specific responses of cellular processes to lowered IIS acting in concert to ameliorate ageing
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