Study On Mechanism Of Leucine Enhancing Physiological Activity And Extending Lifespan Of C.elegans

Exploring the mystery of aging has already become one of the most popular subjects in life science.Lifespan could be complicatedly affected by both genetic factors and environment.According to recent discoveries we can conclude that various external factors such as nutrition intake and dietary restriction all can change lifespan at different degrees.Furthermore,the effect of signaling pathways on lifespan has been clearly confirmed on different organismal models but the correlation between pathways of nutrition metabolism and aging regulatory pathways is poorly understood.In this project we used Caenorhabditis elegans(C.elegans)to detect the effect of branched chain amino acids(BCAAs)on lifespan and healthspan via intake of Leucine(Leu),Isoleucine(Ile)and Valine(Val)and explore its molecular mechanisms.Firstly,we detected the effect of BCAAs on lifespan in C.elegans by adding three different concentrations(0.1m M,1m M and 10 m M)of Leu,Ile and Val separately to the Nematode Growth Medium(NGM).It showed that intake of 1m M and 10 m M Leu could extend lifespan significantly by 13%.According to the results of egg counting and body length measurement we also found that the body of worms fed with Leu is usually longer than the control.What is interesting is that Leu can not only extend lifespan of worms but also increase resistance to oxidative damage,heat stress and UV radiation.To better understand the molecular mechanisms how Leu extends lifespan significantly in C.elegans we used local gene network(LGN)to combine metabolism pathways of amino acid with the mammalian target of rapamycin(m TOR)signaling pathway together.Then we futher checked whether the lifespan extension of Leu was dependent on age-1,daf-2 and daf-16 with the use of mutants.Interestingly,the extensin of lifespan mediated Leu intake was not replicated in these three genes' mutant strains.In this paper we also further explore the relationship between Leu and some genes with unknown function in the LGN.We collected worms of days 5,10 and 15 fed with and without Leu.Real-time fluorescence quantitative PCR was used to detect the levels of genes expression.It displayed that in addition to several genes from the classical m TOR and IIS signaling pathway,the sgk-1,skpt-1 and raga-1 genes conjugated to the life-control pathway of C.elegans were affected by leucine,the gene expression of sgk-1 and raga-1 was significantly decreased(-70%,-59%),and the gene expression of skpt-1 was significantly increased(+156%).but the changes in these gene expression how to affect lifespan need to be further studied in the future.