Regulation of Fatty Acid Oxidation during ER stress: mechanisms and consequences

内质网应激期间脂肪酸氧化的调节：机制和后果

• 批准号: 9282785
• 负责人: David Thomas Rutkowski
• 金额: $ 30.12万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9282785
• 关键词: Affect; American; Binding; CCAAT-Enhancer-Binding Protein-alpha; CCAAT-Enhancer-Binding Proteins; Catabolism; Chronic; Client; Data; Diabetes Mellitus; Disease; Endoplasmic Reticulum; Environment; Family; Fasting; Gene Expression; Generations; Genes; Genetic Transcription; Glutathione; Goals; Grant; Hepatocyte; Homeostasis; Impairment; In Vitro; Lead; Link; Lipids; Liver; Metabolic; Metabolic Diseases; Metabolic Pathway; Metabolic syndrome; Metabolism; Molecular Chaperones; NADP; Nutritional; Obesity; Organelles; Oxidation-Reduction; Oxides; PPAR alpha; Pathway interactions; Phenocopy; Physiological; Physiological Processes; Production; Protein Import; Proteins; Regulation; Regulator Genes; Repression; Role; Signal Transduction; Stress; Symptoms; Testing; Tissues; Up-Regulation; Work; desensitization; disulfide bond; endoplasmic reticulum stress; experimental study; fatty acid oxidation; feeding; human disease; improved; in vivo; lipid metabolism; novel; oxidation; promoter; protein folding; protein misfolding; public health relevance; response; sensor; transcription factor; transcription factor CHOP

 DESCRIPTION (provided by applicant): The unfolded protein response (UPR) is activated by protein misfolding stress in the endoplasmic reticulum (ER), and it culminates in the transcriptional upregulation of ER chaperones, degradation factors, and other genes that help the organelle properly fold or degrade client proteins. However, nutritional flux can elicit ER stress in metabolic tissues such as the liver, and the UPR can in turn regulate metabolic pathways. A number of diseases are associated with both altered metabolism and chronic ER stress, most notably including obesity and its complications. Therefore, it is important to understand how the UPR regulates metabolism and how metabolic flux influences the ER protein processing capacity. Data presented in this proposal show that ER stress in the liver leads to transcriptional suppression of fatty acid oxidation, and that inhibition of fatty acid oxidation alters the oxidizing environment of the ER and protects hepatocytes from stress. These findings suggest that the regulation of fatty acid oxidation by the UPR represents a novel pathway by which the response protects ER function during stress. Yet very little is known about the mechanisms by which the UPR represses rather than activates transcription. Nor is it known how flux through metabolic pathways influences the ER protein folding and processing capacity. Thus, the objective of this work is to understand how ER stress regulates fatty acid oxidation, how fatty acid oxidation regulates ER function, and how these pathways interact during feeding and fasting. The work in this proposal tests the central hypothesis that ER stress leads to direct transcriptional suppression of fatty acid oxidation through the UPR-regulated transcription factor CHOP, and that this in turn alters the oxidative protein folding capacity of the ER to alleviate stress. This hypothesis will be tested by three complementary aims. The first aim will elucidate the gene regulatory network by which the UPR regulates fatty acid oxidation. The role of CHOP in this network will be tested, as will the interactions of CHOP with other C/EBP-family transcription factors and the impact of CHOP action on the master regulators of fatty acid oxidation. In the second aim, the ability of the ER to efficiently import, fold, modify, oxidize, transport, and degrade client proteins will be systematically examined when fatty acid oxidation is manipulated, and the roles of NADPH and glutathione redox in linking fatty acid oxidation to ER function will be tested. The third aim will determine how the relationship between fatty acid oxidation and ER protein processing contributes to the regulation of metabolic activity and ER stress during feeding and fasting. The contribution of CHOP to the suppression of fatty acid oxidation during feeding and its enhancement during fasting will be tested, as will the effects of manipulating fatty acid oxidation, NADPH generation, and glutathione oxidation on ER function. Together, these aims will form a cross-disciplinary approach linking ER protein folding, UPR signaling, lipid metabolism, and redox homeostasis.

 描述（由申请人提供）：未折叠蛋白反应（UPR）由内质网（ER）中的蛋白错误折叠应激激活，最终导致 ER 伴侣、降解因子和其他帮助细胞器正确折叠或降解客户蛋白的基因的转录上调。然而，营养通量会在肝脏等代谢组织中引起内质网应激，而 UPR 反过来又可以调节代谢途径。许多疾病都与代谢改变和慢性内质网应激有关，其中最引人注目的是肥胖及其并发症。因此，了解 UPR 如何调节代谢以及代谢流如何影响 ER 蛋白加工能力非常重要。 该提案中提供的数据表明，肝脏中的内质网应激会导致脂肪酸氧化的转录抑制，而脂肪酸氧化的抑制会改变内质网的氧化环境并保护肝细胞免受应激。这些发现表明，UPR 对脂肪酸氧化的调节代表了一种新的途径，通过该途径，该反应可以在应激期间保护内质网功能。然而，人们对 UPR 抑制而不是激活转录的机制知之甚少。也不知道代谢途径的通量如何影响内质网蛋白质折叠和加工能力。因此，这项工作的目的是了解内质网应激如何调节脂肪酸氧化，脂肪酸氧化如何调节内质网功能，以及这些途径在进食和禁食期间如何相互作用。该提案的工作测试了中心假设，即内质网应激通过 UPR 调节的转录因子 CHOP 导致脂肪酸氧化的直接转录抑制，这反过来又改变内质网的氧化蛋白折叠能力以减轻应激。这一假设将通过三个互补的目标进行检验。第一个目标是阐明 UPR 调节脂肪酸氧化的基因调控网络。我们将测试 CHOP 在该网络中的作用，以及 CHOP 与其他 C/EBP 家族转录因子的相互作用以及 CHOP 作用对脂肪酸氧化主调节因子的影响。第二个目标是，当操纵脂肪酸氧化时，将系统地检查 ER 有效导入、折叠、修饰、氧化、运输和降解客户蛋白的能力，并测试 NADPH 和谷胱甘肽氧化还原在脂肪酸氧化与 ER 功能之间的作用。第三个目标将确定脂肪酸氧化和内质网蛋白质加工之间的关系如何有助于调节进食和禁食期间的代谢活动和内质网应激。将测试 CHOP 对进食期间抑制脂肪酸氧化及其在禁食期间增强脂肪酸氧化的贡献，以及控制脂肪酸氧化、NADPH 生成和谷胱甘肽氧化对 ER 功能的影响。这些目标将共同形成一种跨学科的方法，将 ER 蛋白折叠、UPR 信号传导、脂质代谢和氧化还原稳态联系起来。