ER glycolipid flippases and congenital disorders of glycosylation

ER 糖脂翻转酶和先天性糖基化障碍

基本信息

批准号：
9069623
负责人：
Johannes Graumann
金额：
$ 21.19万
依托单位：
WEILL MEDICAL COLL OF CORNELL UNIV
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-06-01 至 2018-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9069623
关键词：
Affect Anabolism Antibodies Asparagine Binding Biochemical Biochemical Genetics Biological Assay Bypass Carrier Proteins Cell Adhesion Molecules Cell Surface Receptors Cell secretion Cell surface Cells Cellular biology Characteristics Congenital Disorders Defect Development Disease Dolichol Dolichol Phosphates Endoplasmic Reticulum Epitopes Eukaryota Family Fractionation G-Protein-Coupled Receptors Genetic Genetic screening method Glucosephosphates Glycolipids Glycoproteins Goals HIV Envelope Protein gp120 Head Health Hereditary Disease Hormones Human Human Genetics Human Genome Hydrocarbons Hydrolase I-Cell Disease Individual Inherited Laboratories Lipids Lysosomes Mannose Membrane Membrane Proteins Methods Microsomes Molecular Neurologic Oligosaccharides Pathway interactions Pharmaceutical Preparations Phenotype Polysaccharides Post-Translational Protein Processing Protein Glycosylation Proteins Proteomics Publications Reporting Side Specificity Substrate Specificity Symptoms Tail Technology Testing Time Tissues Triton Triton X100 Vesicle Virus Receptors Yeasts base carboxypeptidase C conditional mutant congenital muscular dystrophy genetic approach glycosylation human disease immunogenicity in vivo innovation interest lipid transport mannose 6 phosphate mannosyl(5)-N-acetyl(2)-glucose novel protein profiling rat Piga protein reconstitution research study yeast genetics

项目摘要

DESCRIPTION (provided by applicant): At least half the proteins encoded by the human genome are N-glycosylated, an essential post-translational modification. Defects in glycosylation underlie more than 100 human genetic disorders. For example, I-cell disease is caused by the inability to construct mannose-6-phosphate epitopes on N-glycans of lysosomal hydrolases, resulting in their secretion from cells rather than localization to lysosomes. Congenital Disorders of Glycosylation (CDGs), a family of severe inherited diseases with neurological and other symptoms, frequently result from defects in protein N-glycosylation. Major gaps remain in our understanding of basic glycosylation pathways. For example, assembly of the oligosaccharide donor for N-glycosylation requires flipping of three different glycolipids (Man5GlcNAc2-PP- dolichol (M5-DLO), mannose phosphate dolichol (MPD) and glucose phosphate dolichol (GPD)) from the cytoplasmic to the luminal side of the ER. These glycolipids have long hydrocarbon tails and very polar head groups. They represent key intermediates in the transition of the N-glycan biosynthetic pathway from the cytoplasmic to the luminal side of the ER. How they are flipped across the ER is a long-standing mystery. While there is compelling evidence that specific ER membrane proteins (flippases) are required, and that they have exquisite specificity for the lipids that they transport, the molecular identity of he flippases is not known. Our goal in this R21 application is to identify the glycolipid flippases responsible for flipping M5-DLO and MPD. We developed methods that recapitulate M5-DLO and MPD flipping in synthetic lipid vesicles and this technology now provides the cornerstone of the strategy that we will deploy to achieve our goal. We will use an innovative quantitative proteomics approach to identify flippase candidates from amongst yeast ER membrane proteins. We will then use our reconstitution-based assays to screen the candidates and evaluate their activity. This will provide conclusive evidence of function that we will corroborate by in vivo tests using yeast genetics. With this strategy we expect to identify, for the first time the flippases themselves. As our approach bypasses the limitations of traditional genetic and biochemical approaches that have thus far failed to provide the molecular identity of these flippases, we believe that we have a unique opportunity to solve this decades-old problem. Our discovery will contribute to basic cell biology by revealing a new class of transport proteins, associated with an undoubtedly novel transport mechanism, and also point to new genetic loci that are associated with CDGs.

描述（由应用程序提供）：至少一半由人类基因组编码的蛋白质是N-糖基化的，这是一种必不可少的翻译后修饰。糖基化缺陷是100多个人遗传疾病的基础。例如，I细胞疾病是由于无法在溶酶体水解酶的N-聚糖上构建甘露糖 - 6-磷酸表位而引起的，从而导致其分泌细胞而不是定位到溶酶体。糖基化（CDG）的先天性疾病（CDG）是一个严重的遗传性疾病，患有神经系统和其他症状，经常是由于蛋白质N-糖基化缺陷而导致的。在我们对基本糖基化途径的理解中，主要差距仍然存在。例如，用于N-糖基化的寡糖供体的组装需要将三种不同的糖脂蛋白（MAN5GLCNAC2-PPP- DOLICHOL（M5-DLO），磷酸甘露糖dolichol（MPD）和葡萄糖磷酸盐（GPD））与Cytopinal cytopinal side cytopinal cytopinal cytopinal cyto side side。这些糖脂具有很长的烃尾和非常极性的头部。它们代表着从细胞质到ER腔侧的N-聚糖生物合成途径的过渡中的关键中间体。它们如何翻过急诊室是一个长期的谜。尽管有令人信服的证据表明需要特定的ER膜蛋白（Flippases），并且它们对它们运输的脂质具有独特的特异性，但尚不清楚He Flippases的分子身份。我们在此R21应用程序中的目标是确定负责翻转M5-DLO和MPD的糖脂爆破。我们开发了合成脂质蔬菜中M5-DLO和MPD翻转的方法，这项技术现在为实现我们的目标提供了策略的基石。我们将使用创新的定量蛋白质组学方法来鉴定酵母ER膜蛋白中的Flippase候选物。然后，我们将使用基于重组的暗杀来筛查候选人并评估他们的活动。这将为我们将证实的功能证据提供结论性的证据通过使用酵母遗传学的体内测试。通过这种策略，我们希望第一次确定flippase本身。随着我们的方法绕过迄今未能提供这些Flippases的分子身份的传统遗传和生化方法的局限性，我们认为我们有一个独特的机会来解决这个数十年的问题。我们的发现将通过揭示与无疑是新型运输机制相关的新型运输蛋白来促进基本细胞生物学，并指向与CDG相关的新遗传环境。