Pathophysiology of Conduction Block in HNPP

HNPP 传导阻滞的病理生理学

基本信息

批准号：
8816387
负责人：
JUN LI
金额：
$ 36.23万
依托单位：
VANDERBILT UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-03-15 至 2020-02-29
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8816387
关键词：
Ablation Actins Action Potentials Adherens Junction Adhesions Animal Disease Models Animal Model Area Axon Blindness Cell model Complex Data Defect Demyelinations Disease Dislocations Excision F-Actin Failure Functional disorder Funding Human In Vitro Inherited Knockout Mice Label Limb structure Literature Maintenance Mechanical Stress Membrane Proteins Molecular Monomeric GTP-Binding Proteins Mus Muscle Weakness Mutation Myelin Nerve Nerve Fibers Paralysed Pathology Patients Peptides Peripheral Nervous System Diseases Permeability Phenotype Role Schwann Cells Sensory Shunt Device Signal Transduction Site Stream Testing Therapeutic Trials Tight Junctions Transgenic Mice Wit disability hereditary neuropathy in vivo inhibitor/antagonist mouse model nervous system disorder novel p21 activated kinase polymerization pressure prevent protein complex public health relevance seal virtual

项目摘要

DESCRIPTION (provided by applicant): Mutations in human PMP22 cause the most common forms of inherited peripheral nerve diseases, which include hereditary neuropathy with liability to pressure palsies (HNPP) with heterozygous deletion of PMP22. Patients with HNPP presents with focal sensory loss and muscle weakness that are related to the conduction block. We have discovered that PMP22 deficiency impairs action potential propagation in the absence of segmental demyelination. This conduction defect is likely resulted from abnormally increased permeability of myelin through disruption of myelin junctions. In the present study, we will investigate how junction complexes are disrupted through their abnormal maintenance in PMP22 deficient nerves. Aim 1: Test the hypothesis that PMP22 deficiency increases actin polymerization at myelin junctions, leading to removal of myelin junction protein complexes. Our preliminary study has demonstrated a remarkable increase of F-actin overlaps with the areas that show disruption of junction protein complexes. We will utilize genetically labeled F-actin mouse model to track dynamics of F-actin formation. We will further test how PMP22 deficiency activates the actin polymerization. Aim 2: Removal of p21-activated kinase (PAK1) reverses the increase of F-actin in PMP22 deficient nerves, and thereby prevents myelin junction complexes from being disrupted. Our preliminary results show an abnormal increase of PAK1 activity in Pmp22+/- nerves. Ablation of Pak1 in Pmp22+/- mice reverses abnormal myelin permeability. We will use the double knockout mice (Pmp22+/- /Pak1-/-) to determine whether removal of PAK1 suppresses the formation of F-actin, and dislocation of junction complexes in HNPP mouse model. Moreover, utilizing our newly produced transgenic mouse expressing PAK-inhibiting peptides under the control of inducible Schwann cell-specific cre, we will determine the temporal requirement in rescuing junction abnormalities via PAK inhibition. Aim 3: Systemic administration of PAK1 inhibitor reverses the phenotype in the HNPP mouse model. A successful reversal of abnormal myelin permeability by deletion of Pak1 in Pmp22+/- mice strongly justifies a therapeutic trial in Pmp22+/- mice using PAK1 inhibitors. Taken together, these three aims will further substantiate the pathogenic roles of myelin junction disruption and abnormal actin polymerization in HNPP. We are optimistic that a therapy will likely be developed through this study. Because myelin junctions are essential complexes that seal myelin, results derived from this study may have broad applications in other myelin diseases.

描述（申请人提供）：人类PMP22中的突变导致最常见的遗传性周围神经疾病，其中包括遗传神经病，对压力别真度（HNPP）具有PMP22的杂合缺失。 HNPP患者出现了与传导阻滞有关的局灶性感觉丧失和肌肉无力。我们已经发现，在缺乏分段脱髓鞘的情况下，PMP22缺乏会损害动作电位的传播。这种传导缺陷可能是由于髓磷脂连接处的破坏而异常增加的髓磷脂渗透性。在本研究中，我们将通过PMP22缺乏神经中的异常维护来研究结构络合物如何破坏连接络合物。 AIM 1：检验以下假设：PMP22缺乏会增加髓鞘连接处肌动蛋白聚合，从而导致髓鞘连接蛋白复合物的去除。我们的初步研究表明，F-肌动蛋白重叠与显示结蛋白复合物破坏的区域的重叠显着增加。我们将利用遗传标记的F-肌动小鼠模型来跟踪F-肌动蛋白形成的动力学。我们将进一步测试PMP22缺乏如何激活肌动蛋白聚合。 AIM 2：去除P21激活的激酶（PAK1）会逆转PMP22缺乏神经中F-肌动蛋白的增加，从而防止髓鞘连接络合物被破坏。我们的初步结果表明，PMP22 +/-神经中PAK1活性异常增加。 PMP22 +/-小鼠中Pak1的消融会逆转异常的髓磷脂渗透性。我们将使用双基因敲除小鼠（PMP22 +/-/pak1 - / - ）来确定去除PAK1是否抑制了HNPP小鼠模型中F-肌动蛋白的形成和连接络合物的脱位。此外，利用我们在诱导型Schwann细胞特异性CRE控制下表达抑制PAK抑制肽的新的转基因小鼠，我们将通过PAK抑制来确定拯救结的异常的时间要求。 AIM 3：PAK1抑制剂的系统给药会逆转HNPP小鼠模型中的表型。 PMP22 +/-小鼠中PAK1的删除成功地逆转了异常的髓磷脂通透性，这在PMP22 +/-小鼠中使用PAK1抑制剂在PMP22 +/-小鼠中进行了强烈合理。综上所述，这三个目标将进一步证实HNPP中髓鞘连接破坏和异常肌动蛋白聚合的致病作用。我们乐观地认为，这项研究可能会开发一种疗法。由于髓磷脂连接是密封髓磷脂的重要复合物，因此从这项研究中得出的结果可能在其他髓磷脂疾病中具有广泛的应用。