Homeostasis functions of SKN-1A/Nrf1

项目摘要 在这个项目中，我们将研究我们在C中发现的两个重要的稳态/应激反应。 优雅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Nrf 1（NF-E2相关因子1）。SKN-1A/Nrf 1存在于内质网中，并正常维持蛋白酶体 程度.然而，在我们称之为SKN-1A/Nrf 1脂质稳态反应的途径中，SKN-1A被激活， 不依赖于单不饱和脂肪酸油酸（OA）的蛋白酶体活性，通过对ER的影响 膜和代谢机制。反过来，SKN-1A降低脂肪水平，增强蛋白质稳态， 寿命在第二种反应中，SKN-1A被核糖体组装应激激活，出乎意料的是， 诱导代谢危机，其中脂质和特定氨基酸（AA）耗尽。SKN-1A可以抵消这一点 通过增加AA水平，改善蛋白质稳定和支持翻译来应激。核糖体应激也可以 通过AA喂养可以改善，这部分逆转了这些代谢缺陷。我们的发现增加了一个新的 我们对蛋白质合成稳态的理解。它们也可能与人类有关。 核糖体病，如钻石黑扇贫血（DBA），一种由核糖体亚基 突变，并建议潜在的代谢治疗策略，这些疾病。SKN-1A 功能提供了一个窗口，对新陈代谢和衰老至关重要的机制。 在目标1中，我们将重点关注SKN-1A/Nrf 1脂质稳态反应。我们将研究SKN-1A 通过特定的机制和在某些组织中起作用，以促进健康和寿命，以应对OA， 进行细胞培养实验，以测试我们的模型，即这种反应的关键特征在人类中是保守的。 在目标2和3中，我们将进一步发展我们的模型，以了解核糖体应激如何影响生物体， 抵消SKN-1A，并检查这些机制的保护。在目标2中，我们将检验我们的假设 受损的核糖体装配的代谢需求诱发了我们所观察到的代谢危机。我们 将通过协作稳定同位素示踪代谢组学来阐明这些代谢需求的原因 途径分析和脂质组学。我们的代谢组学将部分通过识别特定的AA来指导 可以挽救核糖体应激和SKN-1A缺乏的影响的组合。我们还将确定 由核糖体应激和SKN-1A缺乏引起的翻译缺陷部分通过以下途径介导 AA水平降低，影响mTORC 1信号传导和/或核糖体停滞。在目标3中，我们将研究 SKN-1A和AA可用性对于核糖体扰动诱导的寿命延长的重要性。我们将 还确定SKN-1A/Nrf 1对核糖体应激的反应在人类细胞中是否保守，包括 合作研究人Nrf 1和AA补充剂是否在体外人体中有益 红系DBA模型。

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.