Mitochondrial depolarization, mitophagy, and mitochondrial DAMPs in ALD

酒精相关性肝病(ALD)是肝脏相关死亡的主要原因。乙醇(Etoh) 对肝脏的损害仍然知之甚少，治疗方法也缺乏或未经证实。更好地理解 肝脏处理、处理和响应乙醇的机制是制定策略所必需的 避免和治疗酒精对肝脏的危险影响，特别是肝纤维化和肝硬变。乙醇 饮酒会导致酒精新陈代谢(SIAM)迅速增加，这与 线粒体呼吸增加。我们的工作揭示了可逆的肝脏线粒体去极化 (MtDepo)，增加小鼠无水乙醇后线粒体DNA(MtDNA)的释放 治疗先于脂肪性肝炎和肝纤维化。在这里，我们以这些发现为基础来描述 本文综述了乙醇诱导线粒体死亡的信号、途径和机制，以及乙醇诱发线粒体死亡和恢复的信号、途径和机制。 诱导有丝分裂；3)线粒体Depo下游星状细胞活化和纤维化。总体而言，我们假设 MtDepo是一种适应性反应，刺激线粒体更快的NADH氧化来供应 乙醇代谢所需的NAD+，但长期而言，mtDepo变得不适应，导致紊乱 线粒体损伤相关分子模式(MtDAMPs)的有丝分裂和释放，如mtDNA， 最终导致肝脏终末期肝病。在具体目标1中，我们将描述这些机制 乙醇诱导mtDepo的发生和恢复，特别是不同质子的开放和关闭的作用 无水乙醇诱导线粒体死亡和线粒体生物发生修复功能线粒体的泄漏途径 在新陈代谢中被消除。在特定的目标2中，我们将描述无水乙醇后的吞丝分裂方式 治疗。具体地说，我们将确定乙醇诱导的mtDepo引发的有丝分裂是否涉及经典的 PINK1/Parkin泛素化途径，由线粒体肿胀导致内膜突出触发 如前期工作中观察到的，通过破裂的外膜释放mtDNA，或两者兼而有之。具体而言 目的3，我们将确定mtDAMPs(如mtDNA)的途径(可能与乙醛协同作用 由肝脏乙醇代谢产生)在星状细胞中诱导促纤维化反应 关注mtDNA传感Toll样受体-9(TLR9)的作用，其缺陷可降低酒精诱导的酒精性损伤 肝脏损伤。总而言之，这些目标将增加我们对两种疾病发病机制的理解 和从mtDepo中恢复以及mtDepo诱导的异常有丝分裂如何导致mtDAMP释放 导致星状细胞活化，最终导致肝纤维化。这个项目的发现将使 治疗和预防酒精性肝病的新机制疗法的发展。

Alcohol-associated liver disease (ALD) is the leading cause of liver-related mortality. How ethanol (EtOH) damages the liver remains poorly understood, and therapies are lacking or unproven. A better understanding of the mechanisms by which the liver handles, processes, and responds to EtOH is needed to develop strategies to avoid and treat the dangerous hepatic ramifications of alcohol, particularly fibrosis and cirrhosis. EtOH consumption produces a swift increase in alcohol metabolism (SIAM) that is associated with a commensurate increase of mitochondrial respiration. Our work reveals reversible hepatic mitochondrial depolarization (mtDepo), increased mitophagic burden, and release of mitochondrial DNA (mtDNA) in mice after EtOH treatment, that precedes hepatic steatohepatitis and fibrosis. Here, we build on these findings to characterize the signals, pathways, and mechanisms of 1) onset and recovery from EtOH-induced mtDepo, 2) mtDepo- induced mitophagy, and 3) stellate cell activation and fibrosis downstream of mtDepo. Overall, we hypothesize that mtDepo is an adaptive response stimulating more rapid mitochondrial NADH oxidation to supply NAD+ required for EtOH metabolism, but chronically, mtDepo becomes maladaptive, causing disordered mitophagy and release of mitochondrial damage-associated molecular patterns (mtDAMPs) like mtDNA, leading ultimately to hepatic end stage liver disease. In Specific Aim 1, we will characterize the mechanisms of onset and recovery of EtOH-induced mtDepo, specifically the role of opening and closing of different proton leak pathways in inducing mtDepo and of mitochondrial biogenesis to restore functional mitochondria after EtOH is metabolically eliminated. In Specific Aim 2, we will characterize the manner of mitophagy after EtOH treatment. Specifically, we will determine if mitophagy initiated by EtOH-induced mtDepo involves the classical PINK1/Parkin ubiquitination pathway, is triggered by mitochondrial swelling leading to inner membrane herniation through a ruptured outer membrane with release of mtDNA as observed in preliminary work, or both. In Specific Aim 3, we will determine pathways by which mtDAMPs (like mtDNA) (possibly in synergism with acetaldehyde generated from hepatic EtOH metabolism) elicit a profibrogenic response in stellate cells with particular attention of the role of mtDNA-sensing toll-like receptor-9 (TLR9) whose deficiency decreases alcohol-induced liver injury. Together, these aims will increase our understanding of mechanisms underlying both the onset and recovery from mtDepo and how mtDepo-induced dysregulated mitophagy leads to mtDAMP release causing stellate cell activation and ultimately hepatic fibrosis. The findings of this project will allow development of new mechanism-based therapeutics to treat and prevent alcoholic liver disease.