Mitochondrial Metabolism Shifts Characterized by Quantitative Mass Spectrometry in Insulin Signaling-regulated Longevity of C.elegans
Aging is a time-related multifaceted physical functional decline process affected by combination of genetic and environmental factors. As unique bioenergetics factories in eukaryotic cells, mitochondria are proven to keep a close link with aging by increasing evidence. This study systematically investigated the mitochondrial functions in daf-2 induced aging C.elegans. We find that daf-2 worms are able to maintain a youthful mitochondrial morphology and have higher levels of ATP production, basal and maximal respiration at an old age. Quantitative proteomic analyses of isolated mitochondria identified 113 up-regulated and 98 down-regulated proteins in the daf-2 mutants revealed a significantly changes in metabolic activity and translation level in daf-2 mitochondria. These results revealed a shift of metabolic activity in the daf-2 mitochondria, especially in the metabolism of branched-chain amino acid (BCAA), ROS, ß-alanine, propionate and fatty acid (FA), which are important for the daf-2 longevity. daf-2 worms with downregulated metabolic enzymes exhibited enhanced protein refolding activity, correlating with lifespan alterations. The amount of mitochondrial ribosomes is approximately 10-20% less in the daf-2 mutants compared to the WT. Slightly decreasing translation elongation factor in normal C.elegans does extend its lifespan. Alteration at mRNA level of mitochondrial translation repressed worms also point to the fatty acid metabolism change in cytoplasm. Our study indicates that mitochondria contribute to daf-2 induced longevity of C.elegans through metabolic disorder and further highlights the crucial role of mitochondria in aging. Overall design: To gain a deeper understanding of the reasons for lifespan changes in daf-2-induced metabolic abnormalities worms, we choose several genes  to perform mRNA-Seq analyses after RNAi treatmentatment.