Homeostasis functions of SKN-1A/Nrf1

SKN-1A/Nrf1 的稳态功能

• 批准号: 10803010
• 负责人: T Keith Blackwell
• 金额: $ 59.9万
• 依托单位: JOSLIN DIABETES CENTER
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-03-01 至 2028-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10803010
• 关键词: Acids; Affect; Aging; Amino Acids; Biological Process; Caenorhabditis elegans; Cell Culture Techniques; Cells; Data; Diamond-Blackfan anemia; Dimensions; Disease; Erythroid; Fatty Acids; Fatty acid glycerol esters; Funding; Genetic Diseases; Genetic Transcription; Health Benefit; Health Promotion; Homeostasis; Human; Human Genetics; Impairment; In Vitro; Lipids; Longevity; Maintenance; Mammals; Mediating; Membrane; Metabolic; Metabolism; Modeling; Monounsaturated Fatty Acids; Mutation; Oleic Acids; Organism; Orthologous Gene; Pathway Analysis; Pathway interactions; Phenotype; Proteasome Inhibition; Protein Biosynthesis; Regulator Genes; Ribosomal Proteins; Ribosomes; Signal Transduction; Site; Stress; Supplementation; Testing; Tissues; Translations; Triglycerides; Unsaturated Fats; Work; acid stress; biological adaptation to stress; experimental study; feeding; human disease; improved; in vivo; insight; knock-down; lipidomics; metabolomics; model organism; multicatalytic endopeptidase complex; nrf1 protein; proteostasis; response; ribosomopathy; stable isotope; transcription factor; treatment strategy

Project Summary In this project we will study two important homeostasis/stress responses we have discovered in C. elegans. Each of these responses is mediated by the conserved transcription factor SKN-1A, the ortholog of human Nrf1 (NF-E2-related factor 1). SKN-1A/Nrf1 resides in the ER and canonically maintains proteasome levels. However, in a pathway we term the SKN-1A/Nrf1 lipid homeostasis response, SKN-1A is activated independently of proteasome activity by the monounsaturated fatty acid oleic acid (OA), through effects on ER membrane and metabolic mechanisms. In turn, SKN-1A reduces fat levels, enhances proteostasis, and extends lifespan. In the second response, SKN-1A is activated by ribosomal assembly stress which, unexpectedly, induces a metabolic crisis in which lipids and specific amino acids (AAs) are depleted. SKN-1A counteracts this stress by increasing AA levels, improving proteostasis, and supporting translation. Ribosomal stress can also be ameliorated by AA feeding, which partially reverses these metabolic deficits. Our findings add a new dimension to our understanding of protein synthesis homeostasis. They are also likely relevant to human ribosomopathies such as Diamond Blackfan Anemia (DBA), a genetic disease resulting from ribosomal subunit mutations, and suggest potential metabolic treatment strategies for such diseases. Each of these SKN-1A functions provides a window into mechanisms that are fundamentally important for metabolism and aging. In Aim 1 we will focus on the SKN-1A/Nrf1 lipid homeostasis response. We will investigate how SKN-1A acts through specific mechanisms and in certain tissues to promote health and lifespan in response to OA, and perform cell culture experiments to test our model that key features of this response are conserved in humans. In Aims 2 and 3 we will further develop our models for how ribosomal stress affects the organism and is counteracted by SKN-1A, and examine conservation of these mechanisms. In Aim 2 we will test our hypothesis that the metabolic demands of impaired ribosomal assembly induce the metabolic crisis we have observed. We will elucidate the cause(s) of these metabolic demands through collaborative stable isotope tracing metabolomic pathway analyses, and lipidomics. Our metabolomics will be guided in part by identification of specific AA combinations that can rescue effects of ribosomal stress and the lack of SKN-1A. We will also determine whether the translation deficits that result from ribosomal stress and lack of SKN-1A are mediated in part through decreased AA levels affecting mTORC1 signaling and/or ribosome stalling. In Aim 3 we will investigate the importance of SKN-1A and AA availability for lifespan extensions induced by ribosomal perturbation. We will also determine whether the SKN-1A/Nrf1 response to ribosomal stress is conserved in human cells, including investigating collaboratively whether human Nrf1 and AA supplementation are beneficial in an in vitro human erythroid DBA model.

项目摘要 在这个项目中，我们将研究我们在C. 优雅女装。这些反应中的每一种都是由保守的转录因子SKN-1A介导的，SKN-1A是 人Nrf1(核因子-E2相关因子1)。SKN-1a/Nrf1位于内质网，规范地维持蛋白酶体 级别。然而，在我们称之为SKN-1A/Nrf1脂稳态反应的途径中，SKN-1A被激活 不依赖于单不饱和脂肪酸油酸(OA)对内质网的蛋白酶体活性 膜和代谢机制。反过来，SKN-1A降低脂肪水平，增强蛋白质平衡，并延长 寿命。在第二个反应中，SKN-1A被核糖体组装应力激活，出人意料的是， 导致脂质和特定氨基酸(AAs)耗尽的新陈代谢危机。SKN-1A抵消了这一点 通过增加AA水平、改善蛋白平衡和支持翻译来应激。核糖体应激也可以 可以通过AA喂养得到改善，这可以部分逆转这些代谢缺陷。我们的发现增加了一个新的 有助于我们理解蛋白质合成的动态平衡。它们也可能与人类有关 核糖体疾病，如钻石黑扇贫血(DBA)，这是一种由核糖体亚单位引起的遗传性疾病 突变，并提出了针对此类疾病的潜在代谢治疗策略。这些SKN-1A中的每一个 功能为了解对新陈代谢和衰老至关重要的机制提供了一个窗口。 在目标1中，我们将重点研究SKN-1A/Nrf1的脂质稳态反应。我们将调查SKN-1A是如何 通过特定机制和在某些组织中促进健康和寿命，以应对骨质疏松症，以及 进行细胞培养实验来测试我们的模型，即这种反应的关键特征在人类中是保守的。 在目标2和目标3中，我们将进一步发展我们的模型，说明核糖体应激如何影响生物体和 被SKN-1A中和，并检查这些机制的保守性。在目标2中，我们将检验我们的假设 核糖体组装受损的代谢需求导致了我们已经观察到的代谢危机。我们 将通过合作稳定同位素示踪代谢组学来阐明这些代谢需求的原因(S) 途径分析和脂类组学。我们的代谢组学将在一定程度上受到特定氨基酸鉴定的指导 可以挽救核糖体压力和SKN-1A缺失影响的组合。我们还将确定是否 核糖体应激和SKN-1a缺失导致的翻译缺陷部分是通过 AA水平降低影响mTORC1信号转导和/或核糖体停滞。在目标3中，我们将调查 SKN-1A和AA的可用性对于核糖体扰动引起的寿命延长的重要性。我们会 还要确定SKN-1A/Nrf1对核糖体应激的反应在人类细胞中是否保守，包括 联合研究人类Nrf1和AA补充剂是否对体外人类有益 红系DBA模型。