Project Summary/Abstract:Myocardial infarction (MI) is an emergency state that requires immediate medical intervention. Coronary arterybypass graft (CABG) surgery or angioplasty procedures have becoming standard but effective treatment.Biomarkers of myocardial cell death are detected postoperatively in nearly all CABG patients or about 30% ofangioplasty patients. Cell death remains detectable in the myocardium even when patients appear to haverecovered from MI. The degree of cell death predicts the risk of developing heart failure and othercomplications. Identifying cytoprotective genes and uncovering their mechanisms of action pave the way fordeveloping new therapies to reduce cardiac injury. Oxidative stress as a result of ischemic or reperfusionand/or major surgery usually causes an inhibition of protein synthesis. We found that Nrf2 mRNA can escapesuch general inhibition and be translated selectively. 5'UTR of Nrf2 mRNA was found to recruit La autoantigenfor ribosomal association and de novo Nrf2 protein translation. Nrf2 is best known as a transcription factor forregulating the expression of antioxidant and detoxification genes. We have found that Nrf2 protectsmitochondria from oxidative injury by physical association. We propose to utilize high resolution LC-MS/MSbased proteomics novel Nrf2 inducers in combination with transgenic animals and in vitro and in vivoexperimental models to test the hypothesis that elevated Nrf2 protein plays an important role in preservation ofmitochondria and protection against myocardial injury. Aim 1 will investigate a novel pathway of Nrf2 inductionby de novo Nrf2 protein translation. Components in the La and ribosomal protein complexes will be uncoveredin an effort to understand the translational machinery under oxidative or ischemic stress in cardiomyocytes.Aim 2 will reveal a novel mechanism of Nrf2 mediated cytoprotection by testing Nrf2 participation inmaintenance of mitochondrial integrity and metabolism. The domain of Nrf2 protein for physical interaction withmitochondria or mitochondrial outer membrane proteins will be identified for testing the significance inmitochondrial integrity metabolism and mitophagy. Aim 3 will provide preclinical evidence for Nrf2 as the leadfor cardiac protection. The importance of de novo Nrf2 protein translation for cardiac protection will bedemonstrated using siRNA against La autoantigen. Contracting cardiomyocytes will be established forselection of Nrf2 inducers with suitable therapeutic indices. Mitochondrial preservation and cardiac protectiveeffect of these compounds will be tested using Nrf2 overexpressing transgenics as a positive control. We haveaccumulated a large volume of data to support the success of the project. Accomplishment of the proposedwork will not only provide needed answers to basic science questions but also present the feasibility of a newcategory of drugs for cardiac protection.