Mitochondrial Respiration and Superoxide Production in Healthy and Failing Heart

描述(由申请者提供)：健康和衰竭心脏的线粒体呼吸和超氧化物生产。在心肌细胞中，线粒体在氧化代谢、离子稳态、信号转导和细胞命运调控等方面发挥着多种功能。线粒体呼吸通过电子传递链(ETC)活性驱动ATP合成和活性氧(ROS)的产生。在衰竭的心脏中，线粒体的呼吸经常受到影响，导致ATP产生减少，矛盾的是，氧化应激增加。因此，确定线粒体呼吸和ROS产生在健康心脏中是如何调节的，以及它们如何在衰竭心脏中对氧化应激起作用是非常有意义的。最近，我们在心肌细胞和心肌的单个线粒体中发现了一种暂时性的超氧化物产生事件，称为超氧化物闪光。初步数据表明，超氧化物闪光需要完整的ETC活性，其频率可以通过生理或病理处理来改变。我们假设，超氧化物闪光与单个线粒体ETC活性的随机加速相耦合，并受到线粒体生物能量学的关键调控因子的调控，包括钙离子、通透性转换孔(PTP)和分裂/融合。如果这一假设是正确的，那么超氧化物闪光可能会起作用。 作为单个线粒体呼吸和ROS产生的综合指标。此外，成像超氧化物闪光可能有助于确定线粒体或胞质ROS是否对衰竭心脏的氧化应激负责。我们提出以下具体目标来确定线粒体呼吸和超氧化物闪光产生的机制耦合及其在心力衰竭氧化应激中的作用：目的1：验证超氧化物闪光产生于线粒体呼吸的瞬时加速并受线粒体钙离子、PTP和分裂/融合动力学调控的假说。目的：验证病理性应激在心力衰竭早期和检测到线粒体功能障碍的明显迹象之前抑制超氧化物歧化活性的假说。目的3：探讨线粒体呼吸功能障碍时线粒体或胞浆ROS升高是否参与氧化应激。

DESCRIPTION (provided by applicant): 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.