Folding, Misfolding, and Function of PMP22

PMP22的折叠、错误折叠和功能

基本信息

批准号：
10658154
负责人：
Bruce D Carter
金额：
$ 56.96万
依托单位：
VANDERBILT UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-04-01 至 2028-01-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10658154
关键词：
26S proteasome 3-Dimensional Address Affect Alleles Amino Acid Sequence Autophagocytosis Cell surface Cells Cellular biology Charcot-Marie-Tooth Disease Coculture Techniques Complex Cytosol Data Defect Destinations Disease EIF-2alpha Fluorescence Microscopy Goals Golgi Apparatus Heterozygote Human Impairment Inherited Knowledge Missense Mutation Modeling Molecular Mus Mutation Myelin Myelin Proteins Nature Nerve Neurons PMP22 gene Paralysed Pathogenicity Pathologic Pathology Pathway interactions Peripheral Peripheral Nervous System Diseases Persons Pharmaceutical Preparations Phosphorylation Phosphotransferases Proteins Rattus Role Schwann Cells Site Syndrome Testing Therapeutic Translations Trisomy Up-Regulation Variant Wild Type Mouse Work base biological adaptation to stress crosslink disorder subtype gain of function hereditary neuropathy knock-down loss of function multicatalytic endopeptidase complex mutant myelination overexpression pressure protein transport trafficking unnatural amino acids

项目摘要

Project Summary Charcot-Marie-Tooth Disease (CMT) is a common debilitating hereditary peripheral neuropathy. The hallmark of CMT pathology is severely defective PNS myelin. There is currently no treatment or cure for this disease. Roughly 75% of all cases of CMT are caused by Schwann cell overexpression of wild type (WT) peripheral myelin protein (PMP22) due to trisomy (type 1A CMT), underexpression of PMP22 (for the WT/null case), or genetically dominant heterozygous (WT/mutant) mutations that alter the PMP22 protein sequence (type E CMT or the more severe Dejerine-Sottas Syndrome--DSS). Important questions remain regarding the molecular mechanisms by which these different classes of defects in PMP22 result in different forms of CMT. Here we propose to address key outstanding questions regarding the molecular bases for the different forms of CMT. Aim 1. How does the trafficking and mis-trafficking of WT PMP22 under CMT1A WT overexpression conditions differ from a folding-defective DSS mutant form of PMP22? We will test the hypothesis that misfolded WT PMP22 ends up in the cytosol, whereas DSS mutants such as L16P PMP22 are trapped in the ER or ER-to-Golgi intermediate compartment (ERGIC). Aim 2. Determine the role of the BAG6 complex (BAG6/GET4/UBL4A) in the cytosolic trafficking of WT PMP22. Our preliminary data suggests that WT PMP22, but not DSS mutant forms of PMP22 interacts with the cytosolic BAG6 complex. This aim will test the hypothesis that the BAG6 complex serves as a holdase for misfolded WT PMP22 to facilitate its healthy shuttling to the proteasome, but that excess PMP22 in CMT1A overwhelms the proteasome, resulting in formation of aggresomes, which are eventually degraded by BAG6-induced autophagy. Aim 3. Determine if excess WT PMP22 inhibits specific proteasome complexes and/or induces phosphorylation of eIF2α in myelinating SCs. Prompted by our preliminary data, this Aim will test the hypothesis that overexpression of WT PMP22 in SCs inhibits the 26S proteasome and activates an integrated stress response (ISR), resulting in phosphorylation of eIF2α to suppress protein translation.

项目概要腓骨肌萎缩症 (CMT) 是一种常见的使人衰弱的遗传性周围神经病。 CMT 病理学的特点是 PNS 髓磷脂严重缺陷，目前尚无治疗方法或治愈方法。大约 75% 的 CMT 病例是由野生型雪旺细胞过度表达引起的。 (WT) 外周髓磷脂蛋白 (PMP22) 由于三体性（1A 型 CMT）、PMP22 表达不足（对于 WT/无效病例），或改变 PMP22 蛋白的遗传显性杂合（WT/突变）突变序列（E 型 CMT 或更严重的 Dejerine-Sottas 综合征 - DSS）。关于 PMP22 中这些不同类别的缺陷导致的分子机制在这里，我们建议解决有关分子的关键悬而未决的问题。不同形式的 CMT 的基础。目标1. CMT1A WT下WT PMP22的贩运和误贩运是如何发生的过表达条件与 PMP22 的折叠缺陷 DSS 突变体形式不同？错误折叠的 WT PMP22 最终进入细胞质的假设，而 DSS 突变体（例如 L16P） PMP22 被捕获在 ER 或 ER-to-Golgi 中间室 (ERGIC) 中。目标 2. 确定 BAG6 复合物 (BAG6/GET4/UBL4A) 在胞质运输中的作用我们的初步数据表明是 WT PMP22，而不是 PMP22 的 DSS 突变形式。与胞质 BAG6 复合物相互作用该目的将检验 BAG6 复合物的假设。作为错误折叠的 WT PMP22 的保持酶，以促进其健康穿梭至蛋白酶体，但是 CMT1A 中过量的 PMP22 会压倒蛋白酶体，导致形成聚集体，最终被 BAG6 诱导的自噬降解。目标 3. 确定过量的 WT PMP22 是否会抑制特定蛋白酶体复合物和/或诱导根据我们的初步数据，该目标将测试髓鞘 SC 中 eIF2α 的磷酸化。假设 SC 中 WT PMP22 的过度表达会抑制 26S 蛋白酶体并激活整合应激反应（ISR），导致 eIF2α 磷酸化以抑制蛋白质翻译。