Folding, Misfolding, and Function of PMP22

PMP22的折叠、错误折叠和功能

• 批准号: 9897595
• 负责人: Melanie Diane Ohi
• 金额: $ 47.18万
• 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 2022-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9897595
• 关键词: Adhesions; Affect; Alleles; Amino Acid Sequence; Awareness; Axon; Biochemical; Biological; Biophysics; Cell physiology; Cell surface; Cells; Charcot-Marie-Tooth Disease; DNA Sequence Alteration; Data; Defect; Dependence; Development; Disease; Electron Microscopy; Endoplasmic Reticulum; Future; Health; Human; Integral Membrane Protein; Kinetics; Lipid Bilayers; Lipids; Membrane Proteins; Molecular; Molecular Chaperones; Molecular Conformation; Mutation; Myelin; Neural Conduction; PMP22 gene; Pathway interactions; Patients; Peripheral Nervous System; Peripheral Nervous System Diseases; Play; Property; Proteins; Quality Control; Role; Schwann Cells; Series; Structure; System; Testing; Therapeutic; Thermodynamics; Tissues; Trisomy; Vesicle; Work; biophysical properties; biophysical techniques; cytotoxic; dysmyelination; experimental study; glycosylation; human disease; insight; loss of function; mutant; novel therapeutics; organizational structure; protein folding; public health relevance; reconstitution; role model; trafficking

 DESCRIPTION (provided by applicant): Folding, Misfolding, and Function of PMP22 Peripheral myelin protein 22 (PMP22) is a tetraspan integral membrane protein that is abundant in myelin of the peripheral nervous system (PNS). Genetic mutations that encode changes in the amino acid sequence of PMP22 are one cause of the common human peripheral neuropathy Charcot-Marie-Tooth Disease (CMTD). CMTD mutations promote misfolding, retention, and possible degradation of PMP22 early in the secretory pathway, leading to loss of function. This results in dysmyelination of PNS axons and the onset of CMTD. While clearly important, the function of PMP22 in myelin and Schwann cell physiology is not well understood. We recently quantitated the thermodynamic folding stabilities of a series of CMTD mutant forms of PMP22 and established that there is a roughly linear correlation between the thermodynamic stability of PMP22 and both cell surface trafficking efficiencies and patient nerve conduction velocities. In Aim 1 we will compare and contrast the folding kinetics and other properties of different CMTD mutant forms of PMP22 in order to examine whether the specific defects that trigger PMP22 instability and terminal misfolding in the cell are the same from mutant to mutant or whether different CMTD mutants have distinctly different defects beyond differences in stability. In Aim 2 we will determine how the instability of CMTD mutant forms of PMP22 is sensed by endoplasmic reticulum quality control. The cellular data from this aim will be integrated with the results of the biophysical experiments of Aim 1 to provide a unified biophysical and cell biological understanding of how defects in PMP22 are recognized by ER quality control. In Aim 3 we will determine how purified PMP22 promotes formation of myelin-like assemblies (MLAs) following reconstitution into lipid vesicles. This will explore the hypotheses that the role of PMP22 in MLA formation is closely related to at least one of its native functions and also that at least some CMTD mutants are likely to disrupt MLA formation in a manner that reflects how mutations promote dysmyelination in PNS tissue. While CMTD is a relatively common disorder (1:3000), to the best of our knowledge this is the only project in the world that includes the biophysical characterization of PMP22. Completion of the above aims will significantly advance our understanding of the folding, misfolding, and function of this myeli membrane protein under conditions of both health and disease. Results will provide direct insight into the molecular mechanisms underlying CMTD and may pave the way for future development of anti-CMTD therapeutics.

 描述（由申请人提供）：PMP 22的折叠、错误折叠和功能外周髓鞘蛋白22（PMP 22）是一种富含外周神经系统（PNS）的髓鞘的四跨膜整合膜蛋白。编码PMP 22氨基酸序列变化的基因突变是常见的人类周围神经病Charcot-Marie-Tooth病（CMTD）的原因之一。CMTD突变促进了分泌途径早期PMP 22的错误折叠、保留和可能的降解，导致功能丧失。这导致PNS轴突的髓鞘形成障碍和CMTD的发作。虽然PMP 22在髓鞘和许旺细胞生理学中的功能显然很重要，但还没有很好地理解。我们最近定量了一系列CMTD突变形式的PMP 22的热力学折叠稳定性，并确定了PMP 22的热力学稳定性与细胞表面运输效率和患者神经传导速度之间存在大致线性相关性。在目的1中，我们将比较和对比不同CMTD突变体形式的PMP 22的折叠动力学和其他性质，以检查在细胞中触发PMP 22不稳定性和末端错误折叠的特定缺陷在突变体之间是否相同，或者不同的CMTD突变体是否具有除了稳定性差异之外的明显不同的缺陷。在目标2中，我们将确定内质网质量控制如何感知PMP 22的CMTD突变形式的不稳定性。来自该目标的细胞数据将与目标1的生物物理学实验的结果整合，以提供关于如何通过ER质量控制识别PMP 22中的缺陷的统一的生物物理学和细胞生物学理解。在目标3中，我们将确定纯化的PMP 22如何促进髓鞘样组装体（MLAs）在重构成脂质囊泡后的形成。这将探讨的假设，在MLA形成的PMP 22的作用是密切相关的至少一个其天然功能，也至少有一些CMTD突变体可能会破坏MLA形成的方式，反映了突变如何促进髓鞘形成障碍的PNS组织。虽然CMTD是一种相对常见的疾病（1：3000），但据我们所知，这是该项目中唯一的项目 包括PMP 22的生物物理表征。上述目标的完成将显著推进我们对这种脊髓膜蛋白在健康和疾病条件下的折叠、错误折叠和功能的理解。结果将提供直接洞察CMTD的分子机制，并可能为未来开发抗CMTD治疗方法铺平道路。