权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Pathophysiology of Myotonia and Periodic Paralysis

肌强直和周期性麻痹的病理生理学

基本信息

批准号：
10641898
负责人：
STEPHEN C. CANNON
金额：
$ 54.61万
依托单位：
UNIVERSITY OF CALIFORNIA LOS ANGELES
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-07-01 至 2026-06-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10641898
关键词：
Acidosis Acute Affect Alleles Biological Assay Biophysics Biopsy Bumetanide Carbohydrates Cells Chlorides Chronic Clinical Trials Computer Models Computer Simulation Coupled Data Defect Development Diet Disease Exercise Extravasation Fasting Fiber Functional disorder Genes Genetically Engineered Mouse Goals Hereditary Disease Hour Human Hyperkalemic periodic paralysis Hypokalemic periodic paralysis Impairment Intervention Investigation Ion Channel Ion Transport Ions K ATPase Knock-in Knock-in Mouse Knowledge Lead Magnetic Resonance Imaging Measurement Microelectrodes Missense Mutation Modeling Mus Muscle Muscle Fibers Mutant Strains Mice Mutation Myopathy Myotonia Oocytes Paralysed Pathogenesis Pathway interactions Patients Phenotype Potassium Channel Preclinical Testing Predisposition Prevention Pump Recovery Recurrence Research Resources Rest Risk Sarcolemma Skeletal Muscle Sodium Sodium Channel Sodium Chloride Specificity Stress System Testing Therapeutic Intervention Validation Variant clinical phenotype cold temperature defined contribution design extracellular gain of function human data improved insight mouse model muscle stiffness mutant mutant mouse model novel strategies novel therapeutic intervention periodic paralysis prevent programs response sensor simulation symporter symptom management therapy design timeline voltage

项目摘要

Project Summary / Abstract Periodic paralysis and myotonia are ion channelopathies of skeletal muscle with debilitating episodes of severe weakness lasting hours to days and activity-dependent muscle stiffness. The long-term goal of this project is to advance our understanding of disease mechanism in these disorders of muscle excitability and to apply this knowledge in the design and pre-clinical testing of therapeutic interventions. Much progress has been made in establishing a causal relationship between the biophysical defect of a mutant channel and the clinical phenotype. For example, over 80 missense mutations have been identified in the NaV1.4 sodium channel, and we have shown by functional expression studies, coupled with simulations of fiber excitability, that mutations with gain of function changes (e.g. impaired inactivation) cause hyperkalemic periodic paralysis (HyperPP) with myotonia. Alternatively, the NaV1.4 mutations in hypokalemic periodic paralysis (HypoPP) are all R/X substitutions in S4 segments of voltage sensor domains that share a common functional defect - the anomalous gating pore leakage current. In all forms of periodic paralysis, the transient attacks of weakness result from sustained depolarization of 𝑉𝑟𝑒௦௧ and loss of excitability, which are often triggered by stress, diet (carbohydrate, salt content, fasting), cold temperature, or exercise. The mechanisms by which these triggers destabilize 𝑉𝑟𝑒௦௧, in the setting of a static defect for a mutant channel, are fundamental open questions in the field and also represent opportunities for therapeutic intervention. A major impediment to progress has been the scarce availability of affected muscle. We created three knock-in mutant mouse models of PP that have robust phenotypes for HyperPP (NaV1.4-M1592V) or HypoPP (NaV1.4-R669H; CaV1.1-R528H). These mouse models have led to new insights on disease mechanism (e.g. recovery from acidosis is a potent trigger of HypoPP) and have led to novel therapeutic interventions that are now in clinical trials (bumetanide inhibition of the NKCC1 cotransporter prevents HypoPP). We will extend our investigations of periodic paralysis by focusing on the impact of ion gradients. Changes in extracellular [K+]o are established triggers for HypoPP (low) or HyperPP (high), but relatively little is known about Na+ and Cl- shifts in PP. Limited human data suggest an acute rise of [Na+]in during an episode of HyperPP or chronically high [Na+]in for HypoPP. In addition, we showed that reducing Cl- influx completely prevents HypoPP attacks. We have developed improved ion-selective microelectrodes, that in combination with the unique resource of our knock-in mutant mice, will enable us to (1) characterize muscle fiber Na+ and Cl- content at rest and during an attack of PP, (2) define the contribution of specific ion transport systems (mutant NaV1.4, NKCC1, Na/K-ATPase, Cl- exchangers) in setting ion concentrations in muscle channelopathies, (3) define the functional consequences of ion gradient perturbations in PP, based on computational modeling and simulation, and (4) use these insights in the design and pre-clinical testing of disease-modifying interventions. .

项目总结/摘要周期性麻痹和肌强直是骨骼肌的离子通道病，持续数小时至数天的虚弱和活动依赖性肌肉僵硬。该项目的长期目标是推进我们对这些肌肉兴奋性障碍的疾病机制的理解，并将其应用于治疗干预措施的设计和临床前测试方面的知识。在建立一个人的生物物理缺陷与他的疾病之间的因果关系方面已经取得了很大的进展。突变通道和临床表型。例如，已经鉴定了超过80个错义突变， NaV1.4钠通道，我们已经通过功能表达研究显示，再加上模拟纤维兴奋性，即具有功能改变增益的突变（例如失活受损）导致高钾血症周期性麻痹（HyperPP）伴肌强直。或者，低钾血症周期性发作中的NaV1.4突变麻痹（HypoPP）是电压传感器域的S4片段中的所有R/X置换，其共享共同的功能缺陷-异常门控孔漏电流。在所有形式的周期性麻痹中，虚弱的发作是由持续的脑电去极化和兴奋性丧失引起的，𝑉𝑟𝑒 通过压力、饮食（碳水化合物、盐含量、禁食）、寒冷温度或运动。的机制在突变通道的静态缺陷的设置中，这些触发器不稳定的触发器是基本开放的这是该领域的问题，也代表了治疗干预的机会。的主要障碍进展是受影响肌肉的稀缺性。我们建立了三个基因敲入突变小鼠模型具有HyperPP（NaV1.4-M1592 V）或HypoPP（NaV1.4-R669 H; CaV1.1-R528 H）的稳健表型的PP。这些小鼠模型导致了对疾病机制的新见解（例如，从酸中毒中恢复是一种有效的治疗方法）。 HypoPP的触发因素），并导致了目前处于临床试验中的新型治疗干预（布美他尼 NKCC 1协同转运蛋白的抑制防止了HypoPP）。我们将通过关注离子梯度的影响来扩展我们对周期性麻痹的研究。细胞外[K+]o的变化是HypoPP（低）或HyperPP（高）的触发因素，但相对较少已知PP中的Na+和Cl-位移。有限的人类数据表明，在一次发作期间， HypoPP或慢性高[Na+]。此外，我们发现完全减少Cl-内流防止HypoPP攻击。我们已经开发了改进的离子选择性微电极，我们的基因敲入突变小鼠的独特资源，将使我们能够（1）表征肌纤维Na+和Cl- 含量在休息和攻击期间的PP，（2）定义的贡献，具体的离子转运系统（突变 NaV1.4、NKCC 1、Na/K-ATPase、Cl-交换剂）在肌肉通道病中设定离子浓度，（3）基于计算建模，定义PP中离子梯度扰动的功能后果，模拟，以及（4）在疾病改善干预措施的设计和临床前测试中使用这些见解。 .