Regulation of cellular bioenergetics by hydrogen sulfide

描述（由申请人提供）：我们最近发现了气态生物介质硫化氢（H2S）的基本生物调节机制。首先，我们已经发现，由酶3-巯基丙酮酸硫转移酶（3-MST）驱动的线粒体内H2S生成过程以生理量产生H2S，其在术语上驱动和平衡氧化磷酸化并维持细胞生物能量学。接下来，我们还发现H2S介导的生物能量功能遵循钟形剂量反应，其中低（内源性）水平的H2S支持细胞能量学，而高水平的H2S变得抑制和有害。此外，我们最近已经证明，H2S在调节血管张力中起着关键作用，至少部分是通过 作为血管磷酸二酯酶5（PDE 5）的生理（内源）抑制剂。调节血流和氧气输送到组织是细胞代谢的关键决定因素;因此，H2S的体内生物能作用是其对局部血流的影响及其对细胞能量过程（氧化磷酸化，糖酵解）的直接调节作用相结合的结果。当前项目的第一个总体目标是表征H2S在体外和体内的生物能量作用。这些过程很可能会 在正常生理中的重要调节作用。此外，该项目的第二个目标是表征H2S在选定的危重病模型（各种病因的循环休克）中的生物能量作用。这第二个总体目标是由临床需要的新方法的实验性治疗循环休克，以及初步数据表明，有显着的改变，在H2S稳态的危重病。我们的调查将描绘的作用（a）的表达变化的H2S产生酶;（B）的氧化还原状态和活性氧/氮物种的变化和（c）的变化程度的组织缺氧/酸中毒的H2S在循环休克的生物功能。我们的项目将最终形成一个统一的概念，将解决目前在该领域的争议，并将定义关键的分子决定因素，这使得H2S的代谢和血管效应有益于有害的循环休克。在目的1中，我们将确定在体外条件下静息时以及在体外模拟循环休克的各种相关代谢方面的条件下H2S对线粒体功能和细胞生物能量学的调节。在目标2中，我们将确定H2S失衡在循环休克期间血管张力调节中的作用。在目标3中，我们将定义 H2S失衡导致循环性休克小鼠模型中多器官衰竭的分子机制。最后，在目的4中，我们将研究H2S在来自体外循环休克患者的白细胞中的细胞生物能量学变化中的作用。这些研究对于生物能量学领域以及危重病的发病机制都具有根本性的相关性。

DESCRIPTION (provided by applicant): We have recently discovered fundamental biological regulatory mechanisms of the gaseous biological mediator hydrogen sulfide (H2S). First and foremost, we have discovered that an intramitochondrial H2S generating process, driven by the enzyme 3-mercaptopyruvate sulfurtransferase (3-MST) produces H2S in physiological amounts, which, in term, drives and balances oxidative phosphorylation and maintains cellular bioenergetics. Next, we have also discovered that H2S-mediated bioenergetic functions follow a bell-shaped dose-response, where low (endogenous) levels of H2S support cellular energetics, while high levels of H2S become inhibitory and deleterious. In addition, we have recently demonstrated that H2S plays a critical role in the regulation of vascular tone, at least in part by acting as a physiological (endogenous) inhibitor of vascular phosphodiesterase 5 (PDE5). Regulation of blood flow and oxygen delivery to tissues is a critical determinant of cellular metabolism; hence, the in vivo bioenergetic role of H2S is the consequence of a combination of its effects on regional blood flow and its direct regulatory actions on cellular energetic processe (oxidative phosphorylation, glycolysis). The first overall goal of the current project is to characterize the bioenergetic roles of H2S in vitro and in vivo. These processes are likely to play important regulatory roles in normal physiology. In addition, the second goal of the project is to characterize the bioenergetic roles of H2S in selected models of critical illness (circulatory shoc of various etiologies). This second overall goal is guided by the clinical need for novel approaches for the experimental therapy of circulatory shock, as well as by preliminary data demonstrating that there are marked alterations in H2S homeostasis in critical illness. Our investigations will delineate the role of (a) changes in the expression of H2S-producing enzymes; (b) changes in redox status and reactive oxygen/nitrogen species and (c) changes in the degree of tissue hypoxia/acidosis in the biological functions of H2S in circulatory shock. Our project will culminate in the formulation of a unifying concept that will resolve current controversies in the field, and will define the key molecular determinants, which render the metabolic and vascular effects of H2S beneficial vs. detrimental in circulatory shock. In Aim 1, we will determine the regulation of mitochondrial function and cellular bioenergetics by H2S under resting in vitro conditions, as well as during conditions, when various relevant metabolic aspects of circulatory shock are modeled in vitro. In Aim 2, we will determine the role of H2S imbalance in the regulation of vascular tone during circulatory shock. In Aim 3, we will define the molecular mechanisms by which H2S imbalance contributes to the development of multiple organ failure in murine models of circulatory shock. Finally, in Aim 4, we will investigate the rol of H2S in changes in cellular bioenergetics in leukocytes from patients with circulatory shock ex vivo. These studies are fundamentally relevant for both the field of bioenergetics, as well as for the pathogenesis of critical illness.