Abstract 12826: Age-related Sestrin2 Maintains OXPHOS Integrity to Modulate Cardiac Substrate Metabolism During Ischemia and Reperfusion

Abstract

Introduction: Sestrin2 (Sesn2) is a stress-inducible protein that declines with aging in the heart. We have reported that rescue Sesn2 levels of aged mouse hearts through gene therapy improves the resistance of aged hearts to ischemic insult caused by ischemia and reperfusion (I/R). Hypothesis: Sestrin2 as a scaffold protein maintains mitochondrial integrity to protect heart from ischemic injury during I/R. Methods: Young C57BL/6J (3-6 months), aged C57BL/6J (24-26 months), and young Sesn2-KO (3-6 months, C57BL/6J background) mice were subjected to 45 min of regional ischemia and 24 hours of reperfusion. The left ventricle of hearts were collected for transcriptomics, proteomics and metabolomics analysis. Results: The protein level of Sesn2 was declined in aged versus young heart. Seahorse measurements demonstrated that Sesn2 deficiency in aged versus young hearts lead to an impaired mitochondrial respiration rate with defects in Complex I and Complex II activity. The Sesn2 targeted proteomics revealed that Sesn2 plays a critical role in maintaining mitochondrial functional integrity through modulating mitochondrial biosynthesis and maintaining oxidative phosphorylation (OXPHOS) complexes. RNA-Sequencing analysis demonstrated that significant alterations in expression of mitochondrial compositional genes and metabolic regulation related genes occurred in both Sesn2 KO and aged hearts versus young hearts. Metabolomics data showed that Sesn2 deficiency in Sesn2 KO and aged versus young hearts augmented glycolysis but compromised citrate cycle process during I/R. The immunoprecipitation data showed that Sesn2 is translocated into mitochondria and directly interacts with OXPHOS components to maintain mitochondrial integrity in response to I/R stress. Furthermore, biochemical analysis revealed that Sesn2 is associated with citrate cycle components to modulate pyruvate dehydrogenase and isocitrate dehydrogenase activities in the mitochondria during I/R stress. Conclusions: Sesn2 serves as a scaffold protein to stabilize mitochondrial OXPHOS in the hearts under I/R stress conditions. Age-related downregulation of cardiac Sesn2 degraded mitochondrial functional integrity in response to ischemic stress in the elderly.