Novel role of endoplasmic reticulum-associated degradation in iron metabolism

内质网相关降解在铁代谢中的新作用

基本信息

批准号：
10364117
负责人：
Shengyi Sun
金额：
$ 38.5万
依托单位：
WAYNE STATE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-12-01 至 2026-11-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10364117
关键词：
Aceruloplasminemia Affect Alleles Anemia Attenuated Biochemical Biogenesis Biological Assay Blood Circulation Ceruloplasmin Clinical Data Defect Disease Dominant-Negative Mutation Endoplasmic Reticulum Event Exhibits Growth Health Hepatic Hepatocyte Homeostasis Human Individual Iron Iron Metabolism Disorders Iron Overload Kidney Diseases Laboratories Link Liver Liver diseases Mediating Missense Mutation Modeling Molecular Molecular Weight Mus Mutation Organ Pathogenesis Pathogenicity Pathologic Peripheral Physiological Physiology Play Proteins Proteomics Quality Control Regulation Reporting Resistance Role Stress Testing Tissues Toxic effect Yeasts cell type cofactor diabetes risk in vivo insight interest iron deficiency iron metabolism iron oxidation loss of function microcytic/hypochromic anemia mutant novel prevent protein complex protein folding protein misfolding proteostasis proteotoxicity recruit response ubiquitin-protein ligase

项目摘要

My laboratory is interested in the (patho-)physiological importance of endoplasmic reticulum (ER)-associated degradation (ERAD), a principal ER quality-control machinery to clear misfolded ER proteins for cytosolic proteasomal degradation. The Sel1L-Hrd1 protein complex represents the most evolutionarily conserved ERAD machinery from yeast to humans. In the past several years, we and others have reported the physiological significance of Sel1L-Hrd1 ERAD in health and disease in a cell-type and substrate-specific manner; however, our understanding of its physiological role remains limited. In the preliminary data of this application, we performed an unbiased proteomics screen that led to the identification of ceruloplasmin (Cp) protein, a ferroxidase regulating iron homeostasis, as an ERAD substrate in the liver. We further showed that both wildtype and a disease mutant Cp are misfolding-prone and are ubiquitinated and degraded by Sel1L- Hrd1 ERAD. Moreover, hepatocyte-specific Sel1L-deficient mice exhibit elevated Cp activity in the circulation and are resistant to iron deficiency-induced hypochromic microcytic anemia. These data point to a critical role of hepatocyte Sel1L-Hrd1 ERAD in Cp biogenesis and systemic iron homeostasis. These findings are exciting because Cp is an essential regulator in iron homeostasis and because Cp missense mutations in humans cause a clinical condition known as aceruloplasminemia, characterized by abnormal iron accumulation in organs. However, the biogenesis of nascent Cp in the ER remains unexplored. Hence, the overarching hypothesis of this application is that Sel1L-Hrd1 ERAD in hepatocytes controls systemic iron homeostasis by regulating the turnover of both wildtype and disease mutant Cp proteins under physiological and pathological conditions, respectively. We will accomplish the following three Aims: (1) Determine the physiological and pathological significance of Sel1L-Hrd1 ERAD in iron metabolism; (2) Delineate the molecular mechanism underlying Cp biogenesis regulated by ERAD; and (3) Delineate the pathological importance of ERAD in the pathogenesis of aceruloplasminemia. Completion of these studies will not only delineate the significance and molecular mechanism underlying ERAD-mediated regulation of iron metabolism, but also provide novel insights into how iron metabolism is regulated under basal and pathological conditions. Relevance to human health: Disorders of iron homeostasis affect millions of individuals worldwide, which cause anemia in deficiency and increase the risk of diabetes, liver and kidney diseases upon overload. This application, with parallel physiological and biochemical studies, will establish a direct link between ERAD and iron metabolism, uncover novel mechanisms underlying ERAD and misfolding-associated proteotoxic stress, and advance our understanding of disease pathogenesis associated with protein folding defects in general.

我的实验室对内质网（ER）相关降解（ERAD）的（病原）生理重要性感兴趣，这是一种主要的ER质量控制机制，可以清除胞质蛋白酶体降解的错误折叠ER蛋白。 SEL1L-HRD1蛋白复合物代表了从酵母到人类的最具进化保守的ERAD机械。在过去的几年中，我们和其他人以细胞类型和底物特异性方式报道了SEL1L-HRD1 ERAD在健康和疾病中的生理意义。但是，我们对其生理作用的理解仍然有限。在该应用程序的初步数据中，我们进行了无偏的蛋白质组学筛选，该筛选导致鉴定Ceruloplasmin（CP）蛋白，一种调节铁稳态的铁氧化酶，作为肝脏中的ERAD底物。我们进一步表明，野生型和疾病突变体CP易于折叠，并被SEL1L-HRD1 ERAD泛滥和降解。此外，肝细胞特异性的SEL1L缺陷小鼠在循环中表现出升高的CP活性，并且对铁缺乏诱导的低染色性微细胞性贫血具有抗性。这些数据表明，肝细胞SEL1L-HRD1 ERAD在CP生物发生和全身铁稳态中的关键作用。这些发现令人兴奋，因为CP是铁稳态中必不可少的调节剂，并且因为人类中的CP错义突变引起了一种临床疾病，称为促脂蛋白血症，其特征是器官中的铁积累异常。但是，ER中新生CP的生物发生尚未探索。因此，该应用的总体假设是，肝细胞中的SEL1L-HRD1 ERAD分别调节在生理和病理条件下的野生型和疾病突变CP蛋白的周转，从而控制了系统的铁稳态。我们将完成以下三个目标：（1）确定SEL1L-HRD1 ERAD在铁代谢中的生理和病理意义；（2）描述由ERAD调节的CP生物发生的分子机制；（3）描述了eRAD在尖脂蛋白血症发病机理中的病理重要性。这些研究的完成不仅会描述伊拉德介导的铁代谢调节的重要性和分子机制，而且还提供了有关在基础和病理条件下如何调节铁代谢的新见解。与人类健康的相关性：铁稳态的疾病会影响全球数百万个人，这会导致贫血缺乏症，并增加糖尿病，肝脏和肾脏疾病的风险。通过平行的生理和生化研究，这种应用将建立ERAD和铁代谢之间的直接联系，发现ERAD和错误折叠相关的蛋白毒性应激的新型机制，并促进我们对一般而言与蛋白质折叠相关的疾病发病机理的理解。