Folding, Misfolding, and Function of PMP22

PMP22的折叠、错误折叠和功能

• 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
• 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

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.

项目摘要 charcot-marie-tooth病（CMT）是一种常见的衰弱的遗传性周围神经病。这 CMT病理学的标志是PNS髓磷脂的严重缺陷。目前没有治疗 这种疾病。所有CMT病例中约有75％是由schwann细胞过表达引起的 （WT）由于三体（1A型CMT），PMP22的不渗透而引起的外周髓磷脂蛋白（PMP22）（对于 WT/NULL情况），或改变PMP22蛋白的遗传显性杂合（WT/突变体）突变 序列（E型CMT或更严重的Dejerine-Sottas综合征-DSS）。仍然存在重要的问题 关于分子机制，PMP22中这些不同类别的缺陷导致的分子机制 不同形式的CMT。在这里，我们建议解决有关分子的关键问题 不同形式的CMT的基础。 目标1。在cmt1a wt下，贩运和贩运wt pmp22如何 过表达的条件与PMP22的折叠缺陷DSS突变体形式不同？我们将测试 不折叠的WT PMP22最终的假设最终出现在细胞质中，而DSS突变体（例如L16p） PMP22被困在ER或ER-Golgi中间室（ERGIC）中。 AIM 2。确定Bag6综合体（Bag6/get4/ubl4a）在胞质贩运中的作用 wt pmp22。我们的初步数据表明，wt pmp22，但不是dss突变形式的pmp22 与胞质Bag6复合物相互作用。这个目标将检验Bag6 Complex的假设 用作错误折叠的WT PMP22的持有酶，以促进其健康的穿梭到蛋白酶体，但这是 CMT1A中的过量PMP22淹没了蛋白酶体，导致脂肪形成 最终被BAG6引起的自噬降解。 AIM 3。确定是否超过WT PMP22抑制特定的蛋白酶体复合物和/或诱导 髓生成SC中EIF2α的磷酸化。在我们的初步数据的提示下，此目标将测试 假设SC中WT PMP22的过表达抑制26S蛋白酶体并激活A 综合应力反应（ISR），导致EIF2α磷酸化抑制蛋白质翻译。