Ventricular arrhythmias often cause sudden cardiac death, a leading cause of death in the United States. Although the detailed mechanisms are not completely understood, there is growing evidence that abnormal calcium cycling plays a fundamental role in the pathogenesis of fatal arrhythmias. Therefore, understanding how calcium handling is regulated and disrupted in the diseased hearts is critical for developing effective antiarrhythmic therapies. In addition to defective calcium homeostasis, increased mitochondrial-derived reactive oxygen species (mdROS) production is another common feature of arrhythmia-prone hearts. We hypothesize that mdROS may be a key factor involved in the abnormal calcium transients and electrical activities in cardiac cells with mitochondrial dysfunction and this redox signaling is mediated by mitochondria-sarcoplasmic reticulum (SR) tethering. The proposed hypothesis is inspired by previous studies showing that: 1) intracellular Ca2+ cycling is largely determined by the redox sensitive Ca2+ channels located on SR, which are in close proximity to mitochondria; 2) mitochondrial Ca2+ uptake relies on mitochondria-SR tethering orchestrated by mitofusin 2 (Mfn2); and 3) suppressing mitochondria Ca2+ uptake not only impairs mitochondrial energetics but also exacerbates cytosolic Ca2+ dysregulation. The hypothesis will be tested by systematically examining the mdROS-induced Ca2+ dysregulation and the role of mitochondria-SR tethering in mediating this redox modulation in the control and diseased (e.g. Mfn2 knockout and heart failure) hearts. Specifically, we will: 1) examine the molecular mechanisms underlying mdROS-induced SR Ca2+ release using an innovative cardiac specific Mfn2 KO mouse model and super- resolution imaging techniques; 2) examine the influence of mdROS on mitochondria-SR tethering and Ca2+ cycling in pressure-overloaded hearts and test if MitoQ, a mitochondrial-targeted ROS scavenger, could reduce the risk of fatal cardiac arrhythmias in the failing hearts by suppressing mdROS production, preventing mitochondrial dysfunction, and alleviating abnormal Ca2+ regulation; and 3) develop a novel computational model of mitochondria-SR tethering to complement experimental studies to understand the role of interorganellar redox signaling in regulating mdROS-induced Ca2+ release in the cardiomyocytes under various pathological conditions. Successful completion of the proposed studies will provide critical insights into the mechanisms by which mitochondrial redox signaling modulates cytosolic Ca2+ cycling and electrical activities in the cardiomyocytes. It will also act as a foundation for future translational studies designed to target these mechanisms for the development of novel antiarrhythmic therapies.

Public Health Relevance

Cardiovascular disease is a major health problem in the United States, which accounts for nearly 500,000 American deaths each year. Of these deaths up to two-thirds occur suddenly as a consequence of sudden cardiac death resulting from ventricular arrhythmias. The proposed studies are highly relevant to public health, as they will provide (i) proof-of-concept evidence for the role of mitochondrial oxidative stress in the pathogenesis of lethal arrhythmias and sudden cardiac death and (ii) important new information and knowledge that can be translated into the design and development of novel and effective antiarrhythmic therapies.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Electrical Signaling, Ion Transport, and Arrhythmias Study Section (ESTA)
Program Officer
Wong, Renee P
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Alabama Birmingham
Internal Medicine/Medicine
Schools of Medicine
United States
Zip Code
Zhao, Meng; Fan, Chengming; Ernst, Patrick J et al. (2018) Y-27632 Preconditioning Enhances Transplantation of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes in Myocardial Infarction Mice. Cardiovasc Res :
Yang, Ruilin; Ernst, Patrick; Song, Jiajia et al. (2018) Mitochondrial-Mediated Oxidative Ca2+/Calmodulin-Dependent Kinase II Activation Induces Early Afterdepolarizations in Guinea Pig Cardiomyocytes: An In Silico Study. J Am Heart Assoc 7:e008939
Yang, Kevin; Long, Qinqiang; Saja, Kamalamma et al. (2017) Knockout of the ATPase inhibitory factor 1 protects the heart from pressure overload-induced cardiac hypertrophy. Sci Rep 7:10501
Cottingham, Christopher; Che, Pulin; Zhang, Wei et al. (2017) Diverse arrestin-recruiting and endocytic profiles of tricyclic antipsychotics acting as direct ?2A adrenergic receptor ligands. Neuropharmacology 116:38-49
Xu, Ningning; Ma, Chao; Ou, Jianfa et al. (2017) Comparative Proteomic Analysis of Three Chinese Hamster Ovary (CHO) Host Cells. Biochem Eng J 124:122-129
Li, Qince; Ni, Rong Ruby; Hong, Huixian et al. (2017) Electrophysiological Properties and Viability of Neonatal Rat Ventricular Myocyte Cultures with Inducible ChR2 Expression. Sci Rep 7:1531
Zhang, Fang; Gannon, Mary; Chen, Yunjia et al. (2017) The amyloid precursor protein modulates ?2A-adrenergic receptor endocytosis and signaling through disrupting arrestin 3 recruitment. FASEB J 31:4434-4446
Goh, Kah Yong; Qu, Jing; Hong, Huixian et al. (2016) Impaired mitochondrial network excitability in failing guinea-pig cardiomyocytes. Cardiovasc Res 109:79-89
Yancey, Danielle M; Guichard, Jason L; Ahmed, Mustafa I et al. (2015) Cardiomyocyte mitochondrial oxidative stress and cytoskeletal breakdown in the heart with a primary volume overload. Am J Physiol Heart Circ Physiol 308:H651-63
Li, Qince; Su, Di; O'Rourke, Brian et al. (2015) Mitochondria-derived ROS bursts disturb Ca²? cycling and induce abnormal automaticity in guinea pig cardiomyocytes: a theoretical study. Am J Physiol Heart Circ Physiol 308:H623-36

Showing the most recent 10 out of 13 publications