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（由申请人提供）：人类 PMP22 突变导致最常见形式的遗传性周围神经疾病，其中包括可能导致以下疾病的遗传性神经病：伴有 PMP22 杂合缺失的压力性麻痹 (HNPP)。 HNPP 患者会出现与传导阻滞相关的局灶性感觉丧失和肌肉无力。我们发现，在没有节段性脱髓鞘的情况下，PMP22 缺陷会损害动作电位传播。这种传导缺陷可能是由于髓磷脂连接破坏导致髓磷脂渗透性异常增加所致。在本研究中，我们将研究 PMP22 缺陷神经中连接复合物的异常维护是如何被破坏的。目标 1：检验以下假设：PMP22 缺乏会增加髓磷脂连接处的肌动蛋白聚合，从而导致髓磷脂连接蛋白复合物的去除。我们的初步研究表明，F-肌动蛋白与连接蛋白复合物破坏区域的重叠显着增加。我们将利用基因标记的 F-肌动蛋白小鼠模型来跟踪 F-肌动蛋白形成的动态。我们将进一步测试 PMP22 缺陷如何激活肌动蛋白聚合。目标 2：去除 p21 激活激酶 (PAK1) 可逆转 PMP22 缺陷神经中 F-肌动蛋白的增加，从而防止髓磷脂连接复合物被破坏。我们的初步结果显示 Pmp22+/- 神经中 PAK1 活性异常增加。 Pmp22+/- 小鼠中 Pak1 的消融可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 是否会抑制 HNPP 小鼠模型中 F-肌动蛋白的形成和连接复合物的错位。此外，利用我们新生产的转基因小鼠在可诱导的雪旺细胞特异性cre的控制下表达PAK抑制肽，我们将确定通过PAK抑制来挽救连接异常的时间要求。目标 3：PAK1 抑制剂的全身给药可逆转 HNPP 小鼠模型中的表型。通过在 Pmp22+/- 小鼠中删除 Pak1 成功逆转髓鞘质通透性异常，有力证明了使用 PAK1 抑制剂在 Pmp22+/- 小鼠中进行治疗试验的合理性。总而言之，这三个目标将进一步证实 HNPP 中髓磷脂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，通过这项研究可能会开发出一种治疗方法。由于髓磷脂连接是密封髓磷脂的重要复合物，因此这项研究的结果可能在其他髓磷脂疾病中具有广泛的应用。