N-Glycosylation And ER Stress

N-糖基化和 ER 应激

基本信息

批准号：
7870355
负责人：
Mark Lehrman
金额：
$ 40.82万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
1987
资助国家：
美国
起止时间：
1987-07-01 至 2013-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7870355
关键词：
Acute Animals Asparagine Binding Biochemical Biological Calnexin Carbohydrates Cell Adhesion Molecules Cell Communication Cell Culture Techniques Cell physiology Cell surface Cells Cellular Stress Cholesterol Clinical Congenital Disorders Data Defect Diabetes Mellitus Disease Dolichol Endoplasmic Reticulum Family Feedback Functional disorder Funding Glycoconjugates Glycogen Glycoproteins Grant Hereditary Disease Herpes Labialis Herpes Simplex Infections Herpesvirus 1 Hexoses Homeostasis Host Defense Host Defense Mechanism Human Genetics Human Virus Immunoglobulins Infection Infectious Agent Insulin Islets of Langerhans Lectin Life Ligands Link Mammalian Cell Mannose Mediating Modeling Modification Molecular Molecular Chaperones Monitor Nervous system structure Normal Cell Obesity PERK kinase Pathway interactions Patients Pharmacological Treatment Phosphotransferases Plasma Cells Polymers Polypeptide Hormones Polysaccharides Process Production Productivity Proteins Publishing Quality Control Receptor Signaling Regulation Research Research Proposals Role Signal Transduction Stress System Testing Transducers Viral Virus Work arm attenuation biological adaptation to stress calreticulin cell type clinically relevant dolichyl-diphosphooligosaccharide - protein glycotransferase endoplasmic reticulum stress fighting glycogenolysis glycosylation human disease inorganic phosphate insight lipooligosaccharide mannose 6 phosphate nervous system disorder novel polypeptide prevent protein folding protein misfolding public health relevance response sensor stressor sugar sugar nucleotide

项目摘要

DESCRIPTION (provided by applicant): Many vitally important proteins which are secreted (such as immunoglobulins and polypeptide hormones) or present at the cell surface (including cell adhesion molecules and signaling receptors) are produced and folded by the endoplasmic reticulum (ER). If the ER has problems folding these proteins, a compensatory "ER stress response" (a.k.a. Unfolded Protein Response) is triggered to enhance ER-related folding processes. ER-produced proteins are frequently N-glycosylated with asparagine-bound sugar polymers (glycans). The glycans are intimately involved in folding of N-glycoproteins, and can also participate in their functions after secretion or reaching the cell surface. The ER-associated lipid-linked oligosaccharide (LLO) Glc3Man9GlcNAc2-P-P-dolichol provides the glycan (Glc3Man9GlcNAc2) used to make N-glycoproteins. Many key features of LLO synthesis have been known for over 20 years, but functional acute regulation of the pathway has been poorly understood. This research proposal focuses on the P.I.'s discovery of LLO synthesis regulation by the ER stress response, mediating a feedback loop which can compensate when LLO insufficiency is the original cause of ER dysfunction. This involves both a "LLO biosynthetic" arm and a counter-intuitive "LLO degradative" arm. Thus LLO production is not hard-wired, but instead is constantly monitored and adjusted. Aim I will elucidate the mechanism by which the ER stress response controls one component of the LLO biosynthetic arm, elevation of levels of nucleotide-sugars which are the precursors of glycans. This Aim will: determine how stress-induced hexose phosphates elevate nucleotide-sugar pools; identify steps in LLO synthesis responsive to nucleotide-sugar control; and explore the stress signal transducer and effector involved. Aim II will provide important new information about an unexpected activity of mannose- 6-phosphate (M6P) and its key role in the LLO degradative arm. The P.I. discovered that M6P is elevated by ER stress, and causes release of glycan from Glc3Man9GlcNAc2-P-P-dolichol. This Aim will: develop mimics and antagonists of M6P to elucidate its cellular action; explore the role of M6P-released glycans in ER homeostasis; and test the hypothesis that the degradative arm represents a novel host defense mechanism against viral envelope N-glycoprotein synthesis (a process using LLO and likely to induce ER stress) with herpes simplex-1 as a model. The clinical relevance is two-fold. First, there are 13 human genetic diseases in the family "Congenital Disorders of Glycosylation" (CDG) Type I, with defective LLO synthesis. CDG-I cells have ER dysfunction due to poor N-glycosylation, and patients have many clinical difficulties. Fundamental new insights into the regulatory systems which may impact CDG-I will be gained from this work. Second, this work will generate new information about the ER stress response, which governs the productivity of the ER, is essential for the secretory functions of plasma cells (immunoglobulins) and pancreatic islets (insulin), and when aberrantly controlled can cause neurological diseases, cholesterol imbalance, and obesity. Public Health Relevance: The public health relevance of this research is three-fold. First, new strategies for treating human diseases in which patients have abnormal carbohydrate attachment to protein will be evaluated. Second, this work will generate new information about the how cells respond to stress, which is an important factor in the production of immunoglobulins to fight infection, in the production of insulin to prevent diabetes, and in diseases involving the nervous system, cholesterol, and obesity. Third, we will evaluate a potential host- defense mechanism against certain infectious human viruses.

描述（由申请人提供）：许多具有分泌的至关重要的蛋白质（例如免疫球蛋白和多肽激素）或存在于细胞表面（包括细胞粘附分子和信号受体），并由内质网（ER）产生并折叠。如果ER在折叠这些蛋白质时存在问题，则会触发补偿性的“ ER应力反应”（又称展开的蛋白质反应）以增强与ER相关的折叠过程。 ER生产的蛋白经常用天冬酰胺结合的糖聚合物（Glycans）进行N-糖基化。聚糖与N-糖蛋白的折叠密切相关，并且在分泌后也可以参与其功能或到达细胞表面。与ER相关的脂质连接寡糖（LLO）GLC3MAN9GLCNAC2-P-P-P-DOLICHOL提供了用于生产N-糖蛋白的聚糖（GLC3MAN9GLCNAC2）。 LLO合成的许多关键特征已有20多年了，但是该途径的功能性急性调节知之甚少。这项研究建议着重于P.I.通过ER应力反应发现LLO合成调节，从而介导了反馈回路，该反馈循环可以补偿LLO不足是ER功能障碍的最初原因。这既涉及“ LLO生物合成”手臂，也涉及违反直觉的“ LLO降解”手臂。因此，LLO生产不是硬线，而是经常监控和调整。目的，我将阐明ER应力响应控制LLO生物合成臂的一个组成部分的机制，核苷酸 - 糖水平的升高，核苷酸 - 糖的水平是Glycans的前体。这个目标将：确定应力诱导的磷酸磷酸盐如何提升核苷酸糖池；确定对核苷酸 - 糖控制反应的LLO合成的步骤；并探索所涉及的应力信号传感器和效应子。 AIM II将提供有关甘露糖6-磷酸（M6P）及其在LLO降解臂中的关键作用的重要新信息。 P.I.发现M6P通过ER应力升高，并导致GLC3MAN9GLCNAC2-P-P-P-DOLICHOL释放聚糖。这个目的将：发展M6P的模仿和拮抗剂来阐明其细胞作用；探索M6P发行的聚糖在ER稳态中的作用；并检验以下假设：降解臂代表一种针对病毒包膜N-糖蛋白合成的新型宿主防御机制（使用LLO的过程，可能会诱导ER应力）作为模型。临床相关性是两个倍。首先，家族中有13种人类遗传疾病“糖基化的先天性疾病”（CDG）I型，具有有缺陷的LLO合成。 CDG-I细胞由于N-糖基化较差而具有ER功能障碍，并且患者遇到许多临床困难。对可能影响CDG-I的监管系统的基本新见解将从这项工作中获得。其次，这项工作将生成有关ER应力反应的新信息，该响应控制ER的生产力，对于浆细胞（免疫球蛋白）和胰岛（胰岛素）的分泌功能至关重要，并且当异常控制时，可能会导致神经系统疾病，胆固醇无效，胆固醇无效和肥胖症。公共卫生相关性：这项研究的公共卫生相关性是三倍。首先，将评估患者对蛋白质异常附着的人类疾病的新策略。其次，这项工作将产生有关细胞对压力的反应的新信息，这是免疫球蛋白产生感染的重要因素，在产生胰岛素以防止糖尿病以及涉及神经系统，胆固醇和肥胖症的疾病中。第三，我们将评估针对某些感染性人类病毒的潜在宿主防御机制。