PMP22基因突变对腓骨肌萎缩症周围神经细胞连接的影响及机制研究

Charcot-Marie-Tooth 1A(CMT1A)is an autosomal dominant disorder caused by heterozygous duplication of the chromosome 17p11.2–12, a DNA segment containing the pathogenetic gene—— PMP22 gene. Although there have been a variety of cellular and molecular alterations that were observed in CMT1A, pathogenic mechanisms in this disease are largely unexplored. Utilizing PMP22+/- mice as a model of HNPP, we show disruption of multiple types of cell junction complexes in peripheral nerve, resulting in increased permeability of myelin and impaired action potential propagation. Our study reveals a novel mechanism by which PMP22 deficiency affects nerve conduction through changes of myelin junction permeability. So using nerve biopsy with CMT1A, we will observe the alteration of Junction when PMP22 gene duplication in these patients' peripheral nerve; Also we will transfect PMP22 gene into cultured nerve cell and observe the alteration of Junctions during PMP22 overexpression; Then we will study the interaction of PMP22 protein with Junctions protein. If PMP22 overexpression alterated the localization and expression of junctions proterin, then we will reveal the molecular mechanisms in CMT1A, which may have an impact on the strategy for the treatment of this disease.

腓骨肌萎缩症(Charcot-Marie-Tooth, CMT)是一组最常见的遗传性周围神经病，其中由染色体17p11.2区域编码的周围髓鞘蛋白22 (PMP22)基因重复突变导致的CMT1A型约占CMT的50%，然而CMT1A疾病的发病机制并不清楚。本项目在我们前期工作观察到PMP22基因缺失导致了周围神经细胞紧密连接密封作用受损、电流外漏而容易引起神经传导阻滞的基础上，拟于以PMP22基因重复突变所致CMT1A患者的神经活检和体外细胞培养作为研究对象，即利用CMT1A患者神经活检观察其周围神经细胞连接的变化；利用体外细胞培养观察PMP22基因过表达时细胞连接蛋白的定位与表达情况及其作用机制；以论证PMP22基因重复突变导致周围神经中细胞连接发生异常的假说，以期揭示CMT1A疾病的发病机制，从而为CMT1A疾病的研究提供新的方向，而且可能对该疾病的治疗策略产生直接的影响。

腓骨肌萎缩症(Charcot-Marie-Tooth, CMT)是一组最常见的遗传性周围神经病，其中由染色体17p11.2区域编码的周围髓鞘蛋白22 (PMP22)基因重复突变导致的CMT1A型约占CMT的50%，然而CMT1A疾病的发病机制并不清楚。我们在前期工作观察到PMP22基因缺失导致了周围神经细胞紧密连接密封作用受损、电流外漏而容易引起神经传导阻滞，因此我们对PMP22基因重复突变对周围神经细胞连接的影响进行研究。我们应用CMT1A患者的神经活检和体外细胞培养作为研究对象，即利用CMT1A患者神经活检观察其周围神经细胞连接的变化；利用体外细胞培养观察PMP22基因过表达时细胞连接蛋白的定位与表达情况及其作用机制。研究发现CMT1A神经中细胞连接蛋白（claudin1、E-cadherin）不连续，在郎飞氏结周围减少或缺失，局部呈节段性缺失；Western-Blot检测CMT1A组中Claudin1、E-cadherin在蛋白表达降低(p<0.05)。细胞水平发现PMP22过表达后细胞连接蛋白表达减少且分布部位发生改变。以上发现说明PMP22过表达导致细胞连接改变是导致CMT1A的病理机制。该研究为CMT1A疾病的研究提供新的方向。