Role of ryanodine receptor dysfunction after spinal cord injury

兰尼碱受体功能障碍在脊髓损伤后的作用

• 批准号: 9751868
• 负责人: Helen M Bramlett
• 金额: --
• 依托单位: JAMES J PETERS VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-10-01 至 2021-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9751868
• 关键词: Affect; Aging; American; Animal Model; Area; Atrophic; Behavioral; Binding; Calcium; Collaborations; Contusions; Coupling; Data; Deterioration; Disseminated Malignant Neoplasm; Dissociation; Drug usage; Fatigue; Fiber; Force of Gravity; Functional disorder; Gait; Hand; Hindlimb; Impairment; Individual; Injury; Intervention; Knock-out; Knowledge; Lead; Lesion; Link; Locomotion; Longevity; Modeling; Motor; Motor Neurons; Mus; Muscle; Muscle Contraction; Muscle Weakness; Muscle function; NADH oxidase; Outcome; Oxides; Paralysed; Pharmaceutical Preparations; Pharmacologic Substance; Pharmacology; Physiological; Production; Quality of Care; Quality of life; Reactive Oxygen Species; Recovery of Function; Rehabilitation therapy; Research Personnel; Resistance; Role; Ryanodine Receptor Calcium Release Channel; Ryanodine Receptors; Sarcoplasmic Reticulum; Skeletal Muscle; Source; Spinal Cord; Spinal Cord Contusions; Spinal Cord transection injury; Spinal cord injury; Testing; Thoracic spinal cord structure; Time; Ursidae Family; Veterans; Weight; Work; arm; disability; effective therapy; experience; experimental study; gait examination; improved; improved functioning; inhibitor/antagonist; muscle strength; neuromuscular function; novel; oxidation; prevent; response; small molecule; treatment effect

Muscles paralyzed by spinal cord injury (SCI) atrophy extensively, are weaker, fatigue more quickly and generate lower specific tension (force produced per unit of cross-sectional area), such that they generate less force in response to maximal motor neuron activation. For individuals with motor-incomplete lesions, interventions that improve specific force and/or fatigue resistance would be obvious opportunities to improve function. A newly recognized cause of impaired specific force production is oxidation/nitrosylation of ryanodine receptors (RyR) which results in dissociation of calstabin and spontaneous opening of RyR thereby impairing RyR gating; the ultimate physiological effect of RyR dysfunction is diminished force of muscle contraction and lower muscle endurance. Small molecules such as S107 bind oxidized/nitrosylated RyR and improve specific force by as much as 50%. Our preliminary data demonstrates extensive oxidation/nitrosylation of RyR in muscle after SCI thus implicating RyR dysfunction in reduced specific force production and endurance of paralyzed muscle after SCI. These changes in RyR are associated with increased expression of NADH oxidase 4 (Nox4) which is a potent source of reactive oxygen species (ROS) that has been linked to RyR. A direct link between Nox4 and oxidation/nitrosylation of RyR is supported by findings that binding of Nox4 to RyR is also increased in muscle after SCI. The overarching objectives of this application are to test the possibility that administration of S107 or a Nox4 inhibitor after SCI will improve skeletal muscle specific tension and endurance, and hence function, and to investigate the role of Nox4 in oxidation/nitrosylation of RyR in skeletal muscle after SCI. Aim 1. To determine the role of elevated Nox4 expression in the oxidation/nitrosylation of RyR in muscle after spinal cord transection. Hypothesis: oxidation/nitrosylation of RyR after SCI results from increased expression and activity of Nox4. Approach. Aim 1A. We will compare SCI and sham-operated groups over time after a spinal cord transection at various times between 1 and 56 days after SCI. We will examine the temporal relationships between oxidation/nitrosylation of RyR and dissociation of calstabin from RyR with changes in Nox4 expression. Aim 1B: Effects of a conditional knockout of Nox4 in skeletal muscle on muscle strength, specific force, fatigue, RyR oxidation after SCI will be determined. Aim 1C: We will compare muscle force production, specific force, fatigue, RyR oxidation/nitrosylation and binding of RyR to calstabin between spinal cord transected mice treated with a Nox4 inhibitor or vehicle. Aim 2) To test the effects of S107 on muscle force production and RyR-calstabin binding interactions after spinal cord transection. Hypothesis: administration of S107 will improve muscle specific force and endurance and increase calstabin binding to RyR but will not alter RyR oxidation/nitrosylation. Approach: We will compare muscle specific force, endurance, binding of calstabin to RyR, and RyR oxidation/nitrosylation between SCI groups administered S107 or vehicle. Aim 3. To A) determine whether S107 or a Nox4 inhibitor improves functional recovery after a contusion SCI. Hypothesis: S107 or a Nox4 inhibitor improves functional recovery in a graded contusion model of mid-thoracic SCI in mice. Approach: Following a mild, moderate or severe contusion spinal cord injury, mice will be treated with the most effective drug (either S107 or GKT137831) from Aims 1 and 2 or vehicle. Effects of the treatment on locomotor function and gait will be determined. Expected Outcomes and Benefits to Veterans. Knowledge gained from such studies may result in new pharmacologic or rehabilitation treatments to improve function after SCI.

脊髓损伤 (SCI) 导致瘫痪的肌肉广泛萎缩、虚弱、疲劳更快 产生较低的比张力（每单位横截面积产生的力），使得它们产生 对最大运动神经元激活的反应力较小。对于运动不完全损伤的个体， 提高特定力量和/或疲劳抵抗力的干预措施将是明显的改善机会 功能。比力产生受损的一个新认识的原因是氧化/亚硝基化 兰尼碱受体 (RyR)，导致 calstabin 解离和 RyR 自发打开 从而损害 RyR 门控； RyR 功能障碍的最终生理效应是减弱 肌肉收缩并降低肌肉耐力。小分子如 S107 结合氧化/亚硝基化 RyR 并将比力提高多达 50%。我们的初步数据表明广泛 SCI 后肌肉中 RyR 的氧化/亚硝基化，因此表明 RyR 功能障碍导致比力降低 SCI 后瘫痪肌肉的产生和耐力。 RyR 的这些变化与 NADH 氧化酶 4 (Nox4) 的表达增加，NADH 氧化酶 4 是活性氧的有效来源 （ROS）已与 RyR 连接。 Nox4 和 RyR 氧化/亚硝基化之间的直接联系是 SCI 后肌肉中 Nox4 与 RyR 的结合也会增加，这一发现支持了这一点。首要的 本申请的目的是测试在治疗后施用 S107 或 Nox4 抑制剂的可能性 SCI 将改善骨骼肌的比张力和耐力，从而改善其功能，并研究 Nox4 在 SCI 后骨骼肌 RyR 氧化/亚硝基化中的作用。 目标 1. 确定 Nox4 表达升高在 RyR 氧化/亚硝基化中的作用 脊髓横断后的肌肉。假设：SCI 后 RyR 的氧化/亚硝基化结果来自 Nox4 的表达和活性增加。方法。目标1A。我们将比较 SCI 和假手术 SCI 后 1 至 56 天的不同时间段脊髓横断后的分组。我们将 检查 RyR 的氧化/亚硝基化与 calstabin 解离之间的时间关系 来自 RyR，Nox4 表达发生变化。目标 1B：条件性敲除 Nox4 对骨骼的影响 SCI后肌肉对肌力、比力、疲劳、RyR氧化的影响将被测定。目标 1C：我们 将比较肌肉力量的产生、比力、疲劳、RyR 氧化/亚硝基化以及 RyR 的结合 在用 Nox4 抑制剂或媒介物处理的脊髓横断小鼠之间进行 calstabin 治疗。 目标 2) 测试 S107 对肌肉力量产生和 RyR-calstabin 结合的影响 脊髓横断后的相互作用。假设：服用 S107 会改善肌肉 比力和耐力并增加 calstabin 与 RyR 的结合，但不会改变 RyR 氧化/亚硝基化。方法：我们将比较肌肉比力、耐力、calstabin 与 施用 S107 或媒介物的 SCI 组之间的 RyR 和 RyR 氧化/亚硝基化。 目标 3. A) 确定 S107 或 Nox4 抑制剂是否可以改善术后功能恢复 脊髓挫伤。假设：S107 或 Nox4 抑制剂可改善分级挫伤的功能恢复 小鼠中胸段 SCI 模型。方法：轻度、中度或重度脊髓挫伤后 损伤，将使用目标 1 和 2 中最有效的药物（S107 或 GKT137831）治疗小鼠，或者 车辆。将确定治疗对运动功能和步态的影响。 退伍军人的预期成果和好处。从此类研究中获得的知识可能会导致 新的药物或康复治疗可改善 SCI 后的功能。