Regulation Mechanism Of Caenorhabditis Elegans Lifespan By Aminoacly-tRNA Synthetase

The aging process is accompanied by dramatic changes in protein synthesis levels,and an increasing number of studies have shown that intervention in the protein synthesis process can significantly affect the lifespan of various model organisms such as yeast,C.elegans and Drosophila,but the specific molecular mechanisms remain unclear.Aminoacyl-t RNA synthetase catalyzes t RNA to load the correct amino acids and is an important factor in the process of protein synthesis.Mutations in aminoacyl-t RNA synthetase gene cause a variety of human genetic diseases,but the research on mechanism of the aminoacyl-t RNA synthetase regulating lifespan is still unknown.In this article,a mitochondrial glutamyl-t RNA synthetase（ears-2）missense mutation with a prolonged lifespan of C.elegans was identified by a forward genetic screening.Therefore,this article carried out an in-depth study on the mechanism of aminoacyl-t RNA synthetase regulating nematode lifespan.First,this article conducted a study on the mechanism of lifespan regulation by ears-2gene.Inhibition of ears-2 gene expression by RNAi was found to significantly extend nematode lifespan,affect mitochondrial function,and activate the mitochondrial unfolded protein response(UPR^mt).The lifespan extension pathway mainly depends on UPR^mt-related transcription factor ATFS-1.Further,inhibition of cytoplasmic glutamyl t RNA synthetase ears-1 gene expression by RNAi significantly shortened lifespan while this treatment significantly reduced the level of protein synthesis.This is the first report that homologous aminyl t RNA synthetases with different subcellular localizations have completely opposite lifespan-regulating effects.Furthermore,this article explored the effects of all aminoacyl-t RNA synthetases in nematodes on lifespan.It was found that only inhibition of mitochondria-specific localized aminoacyl-t RNA synthetase gene expression prolonged nematode lifespan,whereas inhibition of cytoplasmic aminoacyl-t RNA synthetase expression significantly shortened lifespan.It was found that only inhibition of the expression of mitochondria-specific localized aminoacyl t RNA synthetase genes prolonged nematode lifespan,whereas inhibition of cytoplasmic or cyto-mito aminoacyl t RNA synthetase expression significantly shortened lifespan.The lifespan-extending effect caused by inhibition of the mitochondrial aminoacyl-t RNA synthetase gene was achieved by activating UPR^mt response,and the activation level of UPR^mt was positively correlated with the extension of lifespan.In addition,this article also performed fusion protein fluorescence co-localization experiments on several aminoacyl-t RNA synthetases with unclear subcellular localization or contradictory nomenclature in nematodes.This article demonstrated their subcellular localization,further supporting the hypothesis that subcellular localization of aminoacyl-t RNA synthetase affects its lifespan regulation effect.In summary,this article found that inhibition of aminoacyl-t RNA synthase in mitochondria of nematode could extend lifespan by activating UPR^mt,while inhibition of the aminoacyl-t RNA synthase in cytoplasm of nematode may generally affect normal cellular function and thereby significantly shorten lifespan.These results reveal opposing roles for mitochondrial and cytoplasmic aminoacyl t RNA synthetases in lifespan regulation,suggesting that the overall inhibition of cytoplasmic protein synthesis is detrimental to animals and that inhibition of translation may not always promote longevity.This article provides a new mechanism of protein synthesis regulating lifespan and clarifies the ambiguity that inhibiting general protein synthesis can extend lifespan.Moreover,this article provides new knowledge for nematode aminoacyl-t RNA synthetase field,improves the understanding of aminoacyl-t RNA synthetase regulation of lifespan,and promotes the development of new targets and mechanisms for aging intervention.