Liming Yu1, Guang Yang1, Xinjian Zhang1, Peng Wang2,3, Xinyu Weng2,3, Yuyu Yang4, Zilong Li1,5, Mingming Fang1, Yong Xu1,5, Aijun Sun2,3, Junbo Ge2,3. 1. Key Laboratory of Targeted Intervention of Cardiovascular Disease and Collaborative Innovation Center for Cardiovascular Translational Medicine, Department of Pathophysiology, Nanjing Medical University, China (L.Y., G.Y., X.Z., Z.L., M.F., Y.X.). 2. Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital (P.W., X.W., A.S., J.G.), Fudan University, Shanghai, China. 3. Institute of Biomedical Sciences (P.W., X.W., A.S., J.G.), Fudan University, Shanghai, China. 4. State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China (Y.Y.). 5. Institute of Biomedical Research, Liaocheng University, Liaocheng, China (Z.L., Y.X.).
Abstract
BACKGROUND: Excessive accumulation of reactive oxygen species (ROS), catalyzed by the NADPH oxidases (NOX), is involved in the pathogenesis of ischemia-reperfusion (IR) injury. The underlying epigenetic mechanism remains elusive. METHODS: We evaluated the potential role of megakaryocytic leukemia 1 (MKL1), as a bridge linking epigenetic activation of NOX to ROS production and cardiac ischemia-reperfusion injury. RESULTS: Following IR injury, MKL1-deficient (knockout) mice exhibited smaller myocardial infarction along with improved heart function compared with wild-type littermates. Similarly, pharmaceutical inhibition of MKL1 with CCG-1423 also attenuated myocardial infarction and improved heart function in mice. Amelioration of IR injury as a result of MKL1 deletion or inhibition was accompanied by reduced ROS in vivo and in vitro. In response to IR, MKL1 levels were specifically elevated in macrophages, but not in cardiomyocytes, in the heart. Of note, macrophage-specific deletion (MϕcKO), instead of cardiomyocyte-restricted ablation (CMcKO), of MKL1 in mice led to similar improvements of infarct size, heart function, and myocardial ROS generation. Reporter assay and chromatin immunoprecipitation assay revealed that MKL1 directly bound to the promoters of NOX genes to activate NOX transcription. Mechanistically, MKL1 recruited the histone acetyltransferase MOF (male absent on the first) to modify the chromatin structure surrounding the NOX promoters. Knockdown of MOF in macrophages blocked hypoxia/reoxygenation-induced NOX transactivation and ROS accumulation. Of importance, pharmaceutical inhibition of MOF with MG149 significantly downregulated NOX1/NOX4 expression, dampened ROS production, and normalized myocardial function in mice exposed to IR injury. Finally, administration of a specific NOX1/4 inhibitor GKT137831 dampened ROS generation and rescued heart function after IR in mice. CONCLUSIONS: Our data delineate an MKL1-MOF-NOX axis in macrophages that contributes to IR injury, and as such we have provided novel therapeutic targets in the treatment of ischemic heart disease.
BACKGROUND: Excessive accumulation of reactive oxygen species (ROS), catalyzed by the NADPH oxidases (NOX), is involved in the pathogenesis of ischemia-reperfusion (IR) injury. The underlying epigenetic mechanism remains elusive. METHODS: We evaluated the potential role of megakaryocytic leukemia 1 (MKL1), as a bridge linking epigenetic activation of NOX to ROS production and cardiac ischemia-reperfusion injury. RESULTS: Following IR injury, MKL1-deficient (knockout) mice exhibited smaller myocardial infarction along with improved heart function compared with wild-type littermates. Similarly, pharmaceutical inhibition of MKL1 with CCG-1423 also attenuated myocardial infarction and improved heart function in mice. Amelioration of IR injury as a result of MKL1 deletion or inhibition was accompanied by reduced ROS in vivo and in vitro. In response to IR, MKL1 levels were specifically elevated in macrophages, but not in cardiomyocytes, in the heart. Of note, macrophage-specific deletion (MϕcKO), instead of cardiomyocyte-restricted ablation (CMcKO), of MKL1 in mice led to similar improvements of infarct size, heart function, and myocardial ROS generation. Reporter assay and chromatin immunoprecipitation assay revealed that MKL1 directly bound to the promoters of NOX genes to activate NOX transcription. Mechanistically, MKL1 recruited the histone acetyltransferase MOF (male absent on the first) to modify the chromatin structure surrounding the NOX promoters. Knockdown of MOF in macrophages blocked hypoxia/reoxygenation-induced NOX transactivation and ROS accumulation. Of importance, pharmaceutical inhibition of MOF with MG149 significantly downregulated NOX1/NOX4 expression, dampened ROS production, and normalized myocardial function in mice exposed to IR injury. Finally, administration of a specific NOX1/4 inhibitor GKT137831 dampened ROS generation and rescued heart function after IR in mice. CONCLUSIONS: Our data delineate an MKL1-MOF-NOX axis in macrophages that contributes to IR injury, and as such we have provided novel therapeutic targets in the treatment of ischemic heart disease.
Authors: Chao He; Jennifer L Larson-Casey; Dana Davis; Vidya Sagar Hanumanthu; Ana Leda F Longhini; Victor J Thannickal; Linlin Gu; A Brent Carter Journal: JCI Insight Date: 2019-08-22