| Objective It is reported that disorder of uric acid metabolism leads to the development of metabolic diseases such as gout,hyperuricemia,and uric acid stone.The accompanying increase inn inflammation and oxidative stress levels are the culprits leading to cytopathy and aging.A large number of studies have shown that excessive intake of nutrients brings severe risks of uric acid metabolism.As one of the three major nutrients,protein is an indispensable raw material for the body's tissues and organs and for its physiological functions.Therefore,moderate protein intake is essential for the protection of the body's quality of life and the extension of life.Based on the previous research which has discovered a female-specific independent of transformer(FIT),which is a specific satiety signal of amino acids,this study mainly determine the effect and internal mechanism of FIT on protein nutrition metabolism in the body under high protein feeding environment.Method In this study,three kinds of foods with different protein concentration were designed.The standard corn meal food is named normal food(NF).Compared to NF,high protein 1(HP1)contains 2-fold protein dose and high protein 2(HP2)contains 6-fold protein concentration.To determine the effect of FIT on the lifespan of high protein feeding fruit flies,this study first examined the lifespan of w1118 wild-type(WT)flies and various fit mutant flies under NF,HP1,and HP2 food conditions respectively,and examined lifespan when fruit flies were provided with two alternative food containing NF and HP2.The input and output of Drosophila protein nutrition is essential to maintain the protein balance,so this experiment explored the effect of FIT on the feeding and egg-laying behavior.In addition,this study also investigated the effect of FIT protein on the metabolism of Drosophila by detecting the physiological indicators of 25-day-old fruit flies,including body weight,triglycerides,protein and trehalose.Importantly,uric acid is the main product of protein metabolism.This study evaluated the total uric acid level and the concentration of free uric acid in Drosophila.The process of protein metabolism to produce uric acid will be accompanied by the production of reactive oxygen species.This study examined various physiological changes caused by oxidative stress,such as intestinal reactive oxygen species,intestinal integrity and body inflammation markers.Finally,after drugs treatment,the lifespan and physiological indicators of Drosophila were tested to monitor the role of FIT protein in maintaining protein balance and the influence of the above factors on lifespan of flies.Results 1.Lifespan experiments:(1)Compared with wild-type flies,the average lifespan of various fit mutant flies under HP1 food conditions was significantly shorter(p<0.001).(2)In fit81 mutant background,expressing FIT protein in the fat body(FB)had fully rescued on lifespan under HP1 food conditions(p<0.001).(3)After overexpression of FIT protein on the background of wild-type flies,the lifespan under HP2 food condition had a tendency to prolong(p<0.01).(4)Compared with wild-type fruit flies,the lifespan of fit mutant fruit flies was significantly shortened in the optional food containing both NF and HP2(p<0.001).2.Feeding and egg-laying behavior:under the HP1 food condition,the food intake in the mutant fruit flies was comparable with the wild type flies(p>0.05),and the amount of egg-laying by mutant fruit flies was even fewer than wild-type fruit flies(p<0.01).3.The physiological indicators in Drosophila:there was no significant difference in body weight,body protein,and trehalose levels between w1118 and fit81.However,the triglycerides of mutant fruit flies decreased significantly after feeding on HP1 food(p<0.001).The circulating uric acid level of mutant fruit flies after high-protein feeding was significantly lower than that of wild-type fruit flies(p<0.01).4.Experiments on intestinal injury indicators:it was found that the intestinal reactive oxygen species level of the fit mutant Drosophila after HP1 feeding was significantly increased(p<0.01).The level of inflammation markers antimicrobial peptides,a marker of systemic inflammation,had a tendency to rise,and the proportion of deaths due to loss of intestinal integrity in mutant flies was far higher than that of wild-type flies.5.After antioxidant vitamin C and drugs containing purine targets(allopurinol and probenecid)to treat high protein feeding flies,lifespan had different degrees of extension,intestinal reactive oxygen species levels and body uric acid levels also had different degrees of reduction.Conclusion 1.The FIT protein in wild-type fruit flies alleviates lifespan shortened caused by long-term high protein feeding,and the reason for the shortening is not due to the increase in food intake and the increase in egg production.2.In the optional food,FIT guides the selection of fruit flies in healthier foods to maximize lifespan.3.Loss function of FIT leads to defects in lipid metabolism.4.After long-term high protein feeding,FIT changes the dynamic balance of protein metabolite uric acid,and FIT significantly reduces the free uric acid level.5.Circulating uric acid has an anti-oxidant effect.FIT protects fruit flies that live on high protein from the damage of intestinal reactive oxygen species,the increase of inflammation levels,and the destruction of intestinal integrity.6.Through the treatment of antioxidants VC or uric acid excretion drugs probenecid,the consequence of the shortened lifespan of fruit flies caused by high protein feeding can be improved to varying degrees.In this study,it is vital to guide the flies protein intake through exploring the function of FIT protein which leads to longevity by reducing intestinal damage and uric acid metabolism disorders. |
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