A Preliminary Study Of Nrf2-SIRT6 Mediating Lifespan Regulation

Aging is a universal,dynamic,complex process.Although the ageing is not a disease,several diseases are age-related,such as Alzheimer’s disease,diabetes,Parkinson’s disease,atherosclerosis and other metabolic disorder diseases.Human has been plagued by these diseases seriously,and these diseases are the main types which the mankind facing today.The study of aging is increasingly important with the advent of the aging era.Studying on the ageing is gradually from the external to the internal factors,and many theories and anti-aging interventions have been put forward,such as over-expressing some specific sirtuins or adding some bioactive substances to animals food.There are many theories on the aging mechanism,while the oxidative stress theory is the most generally acknowledged.This theory points out that the body will produce ROS due to the damage from the internal or external environment.As the body aging,the production of ROS increases but the removal ability of body abates.This phenomenon will lead to the accumulation of ROS and be harmful for body.When the body undergoes more cell damage than it can repair,the tissues and organs’function will disorder.In oxidative stress theory,a nuclear transcription factor Nrf2 plays an important role.However,some attempts to delay senescence by antioxidant treatments have failed to show good effects.Based on the reported literatures,we explored the new target gene of Nrf2 and the mechanism of a new Nrf2 activation named PQQ.The major work and results:1.animal experimentsSelected two model animals,the worm and Drosophila,then added PQQ to its medium.Counted the survival and the death of these animals at a specified time and drew their survival curves.Results:5mg/L,0.5mg/L PQQ could significantly prolong the lifespan of the worms.The same concentration of PQQ could also extend the longevity of the male fruit flies but have no effects on the longevity of the female ones.2.molecular mechanismThe expression levels of Nrf2 and SIRT6 with the treatment of 0-50μM PQQ were detected by Q-PCR,Western blot and Dual-luciferase reporter assay system in HepG2 cells,293 cells,MEFs;Constructed SIRT6 promoter plasmid and determined the relationship between the transcription factor and SIRT6 promoter activity by Dual-luciferase reporter assay system in 293 cells;Separated heart and lung tissues from different genotypes of Nrf2 mice,analyzed how the Nrf2 regulated other members of the SIRT family by Q-PCR.Results:PQQ could promote the expression levels of Nrf2 and SIRT6;Nrf2 could enhance the promoter activity of SIRT6;Nrf2 could also promote the expression levels of other SIRT family members such as SIRT2,SIRT4,SIRT5 and SIRT7 in mice tissues.Conclusion:We confirmed that the PQQ could significantly extend model animals’ lifespan and increase the Nrf2 mRNA expression level.Furthermore,a series of experiments were done to verify that SIRT6 was a possible target gene of Nrf2 and it might act in conjunction with Nrf2.We could develop new Nrf2 activators,such as PQQ,to slow down the ageing.We also provided a theoretical basis for anti-aging research.