The role of NADPH production in regulating endoplasmic reticulum function and the progression of non-alcoholic steatohepatitis

项目摘要 细胞内稳态不仅对单个细胞的健康至关重要，而且对整个生物体也至关重要。 代谢等细胞过程的失调导致许多疾病的发生 到目前为止还很难完全描述和治疗。治疗的困难部分源于 细胞代谢的复杂性。线粒体是主要的代谢细胞器， 与其他细胞器，包括内质网（ER）。ER负责脂质包装， 氧化蛋白质折叠，并且对破坏这些过程的扰动敏感。对ER的干扰 功能，更好地称为ER应激，导致协调转录的适应性途径的激活， 翻译和新陈代谢使细胞恢复稳态。然而，慢性内质网应激往往导致 疾病，包括代谢性疾病，如非酒精性脂肪性肝炎（NASH）。迄今为止，NASH研究 只关注线粒体或内质网，而不是两者都有。我最近展示了通量通过 线粒体三羧酸（TCA）循环通过细胞氧化还原信号传导影响ER稳态， NADPH和谷胱甘肽。这一观察结果导致假设TCA通量可以传递营养物质 通过NADPH和谷胱甘肽对ER的可用性，以平衡细胞的氧化还原预算， 为蛋白质或脂质的流入准备ER。这也导致了氧化还原通讯的假设 ER和线粒体之间的相互作用导致ER应激诱导的NASH。这两个假设并不相互矛盾。 排他的;可能这种氧化还原机制负责将营养状态传达给ER， 但它对NASH进展没有影响。测试这些假设有可能揭示一个新的 NASH进展的机制。 在这个提案中，我将严格检验NADPH和谷胱甘肽氧化还原导致ER应激的假设- 营养丰富时诱发NASH。我将利用缺乏TCA同工酶异柠檬酸的动物 脱氢酶（Idh 2），其在线粒体基质中产生NADPH。我会评估 这些动物的ER压力和促进NASH的饮食，同时也确定如何营养供应 调节途径特异性NADPH的产生。此外，我将测试假设，氧化还原信号是 通过评估NADPH的隔室特异性水平从线粒体传递到ER， 谷胱甘肽在不同的营养条件下。这项建议的广泛目标是澄清非洲发展新伙伴关系的作用， 谷胱甘肽在调节ER功能的基础上营养状况。成功完成此提案， 有可能刺激研究开发NASH的新疗法，也可能应用于其他代谢性疾病。 疾病和代谢活性组织。

Project Summary Cellular homeostasis is critical not only for the health of individual cells, but for an organism as a whole. Dysregulation of cellular processes, such as metabolism, contribute to the development of numerous diseases that have been difficult to fully characterize and treat thus far. Difficulty with treatment arises in part from the intricacy of cellular metabolism. The mitochondria are the primary metabolic organelles, and they cooperate with other organelles, including the endoplasmic reticulum (ER). The ER is responsible for lipid packaging and oxidative protein folding, and is sensitive to perturbations that disrupt these processes. Perturbations to ER function, better known as ER stress, result in activation of an adaptive pathway that coordinates transcription, translation, and metabolism to return the cell to homeostasis. However, chronic ER stress often leads to disease, including metabolic diseases such as non-alcoholic steatohepatitis (NASH). To date, NASH research has focused on either the mitochondria or ER, but not both. I recently showed that flux through the mitochondrial tricarboxylic acid (TCA) cycle impacts ER homeostasis through cellular redox signaling via NADPH and glutathione. This observation led to the hypothesis that TCA flux could communicate nutrient availability to the ER through NADPH and glutathione in an effort to balance the cellular redox budget and prime the ER for an influx of proteins or lipids. This also led to the hypothesis that redox communication between the ER and mitochondria results in ER stress-induced NASH. These two hypotheses are not mutually exclusive; it is possible that this redox mechanism is responsible for communicating nutrient status to the ER, but that it has no impact on NASH progression. Testing these hypotheses has the potential to uncover a novel mechanism for NASH progression. In this proposal, I will rigorously test the hypothesis that NADPH and glutathione redox lead to ER stress- induced NASH when nutrients are abundant. I will utilize animals lacking the TCA isozyme, isocitrate dehydrogenase (Idh2), which generates NADPH in the mitochondrial matrix. I will assess the susceptibility of these animals to ER stress and a NASH-promoting diet, while also determining how nutrient availability regulates pathway-specific NADPH production. Additionally, I will test the hypothesis that redox signals are communicated from the mitochondria to the ER by assessing compartment-specific levels of NADPH and glutathione under varied nutrient conditions. The broad goal of this proposal is to clarify the role of NADPH and glutathione in regulating ER function based on nutrient status. Successful completion of this proposal has the potential to spur research to develop new therapeutics for NASH, and may also be applied to other metabolic diseases and metabolically active tissues.