Study Of The Correlation Between Mitochondrial Uncoupling Protein And Aging In SD Rats

According to the free radical theory of aging,oxidative stress would be induced when the free radical excessively accumulated in aging process,which could evoke lipid peroxidation and the damage of proteins and DNA.As the result,it will finally cause caducity.ROS,playing important physiological and pathological roles in organisms,is a generic term for a class of active products derived from oxygen like free radicals and related substances.The main resource of ROS is oxidative phosphorylation process in mitochondria.The byproducts of superoxide anion radical,like O₂·^-,cannot be avoided through electron transfer process,which increases the generation rate of free radical in mitochondria.UCP,which locate in mitochondrial inner membrane,can cause a slight uncoupling of oxidative phosphorylation via protons reflow to reduce the generation rate of free radical in mitochondria and oxidative damage.Some studies have already confirmed that aging organisms will be under oxidative stress through the increasing of ROS.According to the antioxidation of UCP in mitochondria,is there a correlation between the expression level of UCP and the aging of the body?In other words,does oxidative stress associated with aging induce high expression of UCP in order to play an antioxidant role?Therefore,SD rats are selected as experimental model to analyze the correlation between UCP and aging systematically.The expression of UCP are specificity in different tissues.Respectively,UCP1 is mainly expressed in BAT;UCP2 is distributed widely in all kinds of tissue;UCP3 can be easily found in muscle tissue;UCP4 and UCP5 are mainly expressed in the nervous system.Based on those condition,the cerebral cortex,heart,liver,lung,kidney and skeletal muscle tissue of SD rats in 2,11,17,20,16 and 34 months old were used as experimental materials in this research.The most stable reference genes which can be used to analyze the expression of UCP were selected from13 commonly used house-keeping genes by RT-qPCR and five software,such as geNorm,NormFinder,BestKeeper,Delta Ct and Comprehensive Ranking,to against the influence of down-regulation of gene expression with aging process.Next,we also use RT-q PCR,Western Blot and transcriptome sequencing to illustrate the expression level of UCP in different tissues through aging.Results:?1?The selection of reference genes is necessary.The comprehensive analysis of five kinds of software have shown that a pair of most stable reference genes should be selected at least for the standardization of subsequent date in the six tissues of different months age.Respectively,they are Tbp and Polr2a,Tbp and Polr2a,Rpl13a and Tbp,Gapdh and Sdha,Tbp and Gusb,Ywhaz and Gusb corresponding to the cortex,heart,liver,lung,kidney and skeletal muscle tissues.?2?Based on the results of the expression level of UCP,UCP1 shows a remarkable increase in the age of 17-34 months in heart tissue;the expression of UCP2 has increased in the age of 11-34 months in cortex tissue.However,in other tissues and other UCP,it has not been able to detect a significant trend of mRNA expression levels rising or falling with aging.?3?The trend of Western Blot of UCP2 and UCP4 in liver,cortex and kidney are the same as the analysis of mRNA.?4?According to the transcriptome sequencing of UCP2,UCP4 and UCP5 have no significant difference in cortex tissue between 2 and 34 months.UCP1 and UCP3were not detected.?5?The result of antioxidant test showed that the content of MDA increased and the activity of SOD decreased in rats aged 2,17 and 34 months.Conclusion:?1?Aging individuals being in oxidative stress and oxidative damage is intensified.This fact is supported by research reports and confirmed by our research results too.However,this study failed to find out the expression level of UCP and the aging of SD rats.There is a consistent correlation.This result once again suggests that the study of physiological functions of UCP is still a long way off.?2?The results of this study presumed that aging and its associated oxidative stress may be a complex state caused by multiple factors.In some cases,we cannot exclude the role of UCP,but the existing results also cannot support the strict correlation between UCP and aging.