The Role Of Age-associated NRF2 Dysfunction In Vascular Medial Calcification And Its Mechanism

Background and Objective:Age-related calcium deposition in tunica media leads to arterial stiffness,high blood pressure and multiple organ damage.Vascular medial calcification is a regulable process,similar to bone formation.Oxidative stress plays a crucial role in the occurrence and development of vascular medial calcification.Nuclear factor erythroid 2-related factor 2(NRF2),an antioxidative transcription factor,contributes to maintaining vascular homeostasis and bone development.In addition,that the activity of NRF2 in cardiovascular system declines with age could be one of the reasons for age-associated structural and functional changes in arteries.However,the regulatory mechanism of NRF2 in vascular medial calcification,especially in age-related vascular medial calcification,is insufficient in research.The study will focus on exploring the role of NRF2 in vascular medial calcification and vascular smooth muscle cell calcification.Furthermore,this research will elaborate whether age-associated NRF2 dysfunction could be a key cause of vascular medial calcification with age.Methods and Results:In vitro,we established a mice aortic smooth muscle cell(MOVAS1)calcification model induced by high phosphate.Through RNA interference(RNAi)and lentivirus transfection,we proved Nrf2-knockout aggravated vascular smooth muscle cell(VSMC)calcification,and the overexpression of Nrf2 can inhibit VSMC calcification.In addition,flow cytometry(FCM)was used to detect reactive oxygen species(ROS),mitochondrial membrane potential(MMP)and apoptosis in VSMC.Results show that Nrf2 overexpression in MOVAS1 reduced ROS and increased MMP.The overexpression of NRF2 also decreased late apoptosis with or without high phosphate.What's more,it decreased early apoptosis induced by high phosphate,but increased early apoptosis in the untreated VSMC.In vivo,we established a vascular medial calcification model induced by high purine diet and a aortic ring calcification model with high phosphate.Smooth muscle specific Nrf2 knockout mice were used to verify that lack of NRF2 aggravate mice vascular medial calcification.In the study,we also used a natural aging mouse model to demonstrate that the aortic rings of the aged mice were more likely calcified,and the expression of NRF2 and its target genes,NQO1 and HMOX1,in mice vascular smooth muscle reduced with age.Furthermore,dimethyl formamide(DMF)and tert-butylhydroquinone(t BHQ),as NRF2 activators,can effectively alleviated the aortic ring calcification in elderly mice.Conclusions:Lack of NRF2 in vascular smooth muscle aggravated the medial calcification and VSMC calcification in mice.The role of NRF2 in early apoptosis could be one of regulatory mechanisms that NRF2 help to eliminate VSMC calcification.Aging accelerated the occurrence and development of calcification,together with the decline of NRF2 function.Age-related NRF2 dysfunction could contribute to vascular medial calcification exacerbated by aging.The application of NRF2 activators will bring a new insight for preventing and treating vascular medial calcification with age.