Mitochondrial Respiration and Superoxide Production in Healthy and Failing Heart. In cardiac myocytes, mitochondrion plays multi-functional roles in oxidative metabolism, ion homeostasis, signal transduction, and cell fate regulation. Mitochondrial respiration through the electron transport chain (ETC) activity drives ATP synthesis and reactive oxygen species (ROS) generation. In the failing heart, mitochondrial respiration is often compromised, resulting in decreased ATP production and, paradoxically, increased oxidative stress. It is therefore of great interest to determine how mitochondrial respiration and ROS production are regulated in the healthy heart and how they contribute to oxidative stress in the failing heart. Recently, we discovered a transient superoxide production event, named superoxide flash, in individual mitochondria of cardiac myocytes and the myocardium. Preliminary data indicate that the superoxide flash requires intact ETC activity, and its frequency is altered by physiological or pathological treatments. We hypothesize that the superoxide flash is coupled to stochastic acceleration of ETC activity in single mitochondria and modulated by key regulators of mitochondrial bioenergetics, including Ca2+, permeability transition pore (PTP), and fission/fusion. If this hypothesis is true, superoxide flashes may serve as a composite index of single mitochondrion respiration and ROS production. Further, imaging superoxide flashes may help determine whether mitochondrial or cytosolic ROS is responsible for oxidative stress in the failing heart. We propose the following specific aims to determine the mechanistic coupling of mitochondrial respiration and superoxide flash production and their role in oxidative stress in heart failure:
Aim 1 : To test the hypothesis that superoxide flash arises from transient acceleration of mitochondrial respiration and is modulated by mitochondrial Ca2+, PTP and fission/fusion dynamics.
Aim 2 : To test the hypothesis that pathological stress inhibits superoxide flash activity at an early stage of heart failure and prior to detection of overt signs f mitochondrial dysfunction.
Aim 3 : To determine whether increased mitochondrial or cytosolic ROS contributes to oxidative stress during mitochondrial respiratory dysfunction.
This project investigates the mechanistic coupling of mitochondrial respiration and bursting superoxide production. Our goal is to establish that decreased superoxide flash activity is a novel and early biomarker for mitochondrial dysfunction, which leads to oxidative stress in heart failure.
|O-Uchi, Jin; Jhun, Bong Sook; Xu, Shangcheng et al. (2014) Adrenergic signaling regulates mitochondrial Ca2+ uptake through Pyk2-dependent tyrosine phosphorylation of the mitochondrial Ca2+ uniporter. Antioxid Redox Signal 21:863-79|
|Gong, Guohua; Liu, Xiaoyun; Wang, Wang (2014) Regulation of metabolism in individual mitochondria during excitation-contraction coupling. J Mol Cell Cardiol 76:235-46|
|Wang, Wang; Asp, Michelle L; Guerrero-Serna, Guadalupe et al. (2014) Differential effects of S100 proteins A2 and A6 on cardiac Ca(2+) cycling and contractile performance. J Mol Cell Cardiol 72:117-25|
|Yu, Qiujun; Lee, Chi Fung; Wang, Wang et al. (2014) Elimination of NADPH oxidase activity promotes reductive stress and sensitizes the heart to ischemic injury. J Am Heart Assoc 3:e000555|
|Wei-LaPierre, Lan; Gong, Guohua; Gerstner, Brent J et al. (2013) Respective contribution of mitochondrial superoxide and pH to mitochondria-targeted circularly permuted yellow fluorescent protein (mt-cpYFP) flash activity. J Biol Chem 288:10567-77|
|Karamanlidis, Georgios; Lee, Chi Fung; Garcia-Menendez, Lorena et al. (2013) Mitochondrial complex I deficiency increases protein acetylation and accelerates heart failure. Cell Metab 18:239-50|