Structure, Folding, and Misfolding of PMP22

描述（由申请人提供）：编码外周髓磷脂蛋白22（PMP 22）的基因中的遗传显性突变导致其序列中的单个氨基酸变化，从而导致髓磷脂缺陷，导致常见的人类周围神经病变，Charcot-Marie-Tooth病IA型（CMTD）。据信，CMTD突变导致分泌途径早期PMP 22的错误组装，导致蛋白质功能丧失，还导致形成潜在的细胞毒性聚集体。该项目的总体目标是阐明CMTD相关突变对这种关键膜蛋白的结构、稳定性和折叠所产生的扰动的分子生物物理性质。我们还试图测试化学分子伴侣是否可以纠正通常观察到的PMP 22的CMTD突变形式的折叠缺陷。目标1.使用NMR光谱表征人PMP 22的野生型（WT）和CMTD突变形式的结构。目的1将检验PMP 22的CMTD突变形式在构象和/或寡聚状态方面不同于WT蛋白的假设。结构信息还将阐明PMP 22的结构/功能关系及其在髓鞘产生和维持中的作用，并将提供对氨基酸突变如何导致CMTD的生物物理学见解。PMP 22结构的确定也将增加目前稀疏的人类膜蛋白结构画廊。目标2.表征PMP 22的WT和CMTD突变体形式的稳定性和折叠动力学。目的2将检验疾病相关的PMP 22突变使蛋白质不稳定的假设。目的2还将检验疾病相关的突变形式的PMP 22折叠比野生型蛋白更慢和/或更低效的假设。我们还将测试PMP 22的CMTD突变形式是否易于聚集。目标3：确定化学分子伴侣是否可以增加PMP 22的CMTD突变形式的细胞表面表达。目的3将测试这样的假设，即PMP 22类似于与涉及蛋白质错误组装的疾病相关的其他人类膜蛋白，并且已经确定可以使用化学分子伴侣恢复正确的折叠和运输。 公共卫生相关性：人类外周髓磷脂蛋白22（PMP 22）的结构，折叠和稳定性的研究将进行解开腓骨肌萎缩症，周围神经病变的分子基础。这项工作的结果预计将有助于这种人类疾病的新的治疗策略。

DESCRIPTION (provided by applicant): Genetically dominant mutations in the gene that encodes peripheral myelin protein 22 (PMP22) lead to single amino acid changes in its sequence that result in defective myelin, underlying the common human peripheral neuropathy, Charcot-Marie-Tooth Disease Type IA (CMTD). It is believed that CMTD mutations result in misassembly of PMP22 early in the secretory pathway, resulting in the loss of protein function and also in the formation of potentially cytotoxic aggregates. The overall goal of this project is to elucidate the molecular biophysical nature of the perturbations made by CMTD-associated mutations to the structure, stability and folding of this critical membrane protein. We also seek to test whether chemical chaperones can correct the folding defects normally observed for CMTD mutant forms of PMP22. Aim 1. Characterize the structures of the wild type (WT) and CMTD mutant forms of human PMP22 using NMR spectroscopy. Aim 1 will test the hypothesis that CMTD mutant forms of PMP22 differ from the WT protein in terms of conformation and/or oligomeric state. Structural information will also illuminate PMP22's structure/function relationships and its role in myelin production and maintenance, and will provide biophysical insight into how amino acid mutations result in CMTD. Determination of PMP22's structure will also add to the currently sparse gallery of human membrane protein structures. Aim 2. Characterize the stability and folding kinetics of WT and CMTD mutant forms of PMP22. Aim 2 will test the hypothesis that disease-related mutations of PMP22 destabilize the protein. Aim 2 will also test the hypothesis that disease-related mutant forms of PMP22 fold more slowly and/or inefficiently than the wild type protein. We will also test whether CMTD mutant forms of PMP22 are aggregation-prone. Aim 3. Determine whether chemical chaperones can increase the cell surface expression of CMTD mutant forms of PMP22. Aim 3 will test the hypothesis that PMP22 is akin to other human membrane proteins that are linked to diseases involving protein misassembly and for which it has already been established that proper folding and trafficking can be restored using chemical chaperones. PUBLIC HEALTH RELEVANCE: Studies of the structure, folding, and stability of the human peripheral myelin protein 22 (PMP22) will be undertaken to unravel the molecular basis for Charcot-Marie Tooth Disease, a peripheral neuropathy. Results from this work are expected to contribute to novel therapeutic strategies for this human disease.