Synaptic and Nerve Terminal Changes and Associated Muscle Weakness of Burn Injury

突触和神经末梢变化以及烧伤相关的肌肉无力

• 批准号: 9247895
• 负责人: Jeevendra Martyn
• 金额: $ 32.84万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9247895
• 关键词: Affect; Agonist; Agrin; Area; Attenuated; Biochemical; Bungarotoxins; Burn injury; Cell physiology; Cholinergic Receptors; Critical Illness; Cues; Cyan Fluorescent Protein; Data; Denervation; Distant; Fatigue; Functional disorder; GTS-21; Green Fluorescent Proteins; Growth; Health Care Costs; Human; Impairment; Inflammatory; Inflammatory Response; Injury; Knock-out; Knockout Mice; Label; Lead; Maintenance; Mediating; Mediator of activation protein; Membrane; Mitochondria; Morbidity - disease rate; Morphology; Motor; Mus; Muscle; Muscle Weakness; Muscle function; Myelin; Nerve; Neural Conduction; Neuregulins; Neuromuscular Junction; Nicotine; Organ; Pathologic; Pharmacology; Phase; Phosphorylation; Play; Process; Protein Isoforms; Proteins; Proto-Oncogene Proteins c-akt; Publishing; Recovery; Rodent; Role; Schwann Cells; Sepsis; Signal Pathway; Signal Transduction; Site; Specificity; Synapses; Testing; Therapeutic; Time; Tissues; Transgenic Mice; Up-Regulation; base; genetic approach; glycogen synthase kinase 3 beta; mitochondrial dysfunction; mortality; neuromuscular; neurotransmission; novel strategies; protective effect; public health relevance; repaired; response

 DESCRIPTION (provided by applicant): Burn injury (BI) leads to neuromuscular dysfunction (NMD), and muscle weakness (MW). The relationship of motor nerve terminal and synaptic changes to MW after BI is unknown. Integrity of neuromuscular junction (NMJ) depends on tropic signals from nerve to muscle mediated via synaptic acetylcholine receptors (AChRs), and on retrograde cues from muscle including pivotal signaling via Akt (a.k.a., PKB) and glycogen synthase kinase-3ß (GSK-3ß) to synapse. Terminal Schwann cells (TSC) function is also essential to NMJ integrity. We posit that inflammatory responses of BI, and mitochondrial dysfunction (MD) of NMJ tissues blunt tropic signaling, and TSC function leading to nerve and synaptic derangements, and these derangements are central to the NMD and MW. The major challenge is how to effectively reverse the inflammatory responses-mediated NMJ changes. TSCs constitutively express α7AChRs isoform, and muscles up-regulate α7AChRs after BI. Published, and our new data show that α7AChRs stimulation with specific agonist, GTS-21, mitigates inflammatory responses, MD and enhances signaling via Akt/GSK-3ß. The hypothesis tested is that stimulation with GTS-21 of α7AChRs, via its pluri-potent actions, will protect NMJ changes in BI mice. Specific Aim 1 tests the hypothesis that synaptic and nerve aberrations of BI lead to NMD and MW. Using Thy1-YFP (yellow fluorescent protein) transgenic mice (depicting motor nerve) and fluorescent-bungarotoxin to label synaptic AChRs, time-dependent nerve and synaptic morphological changes after BI, and their relationship to muscle function (tension and fatigability) will be characterized. Use of Thy1-mito CFP (cyan fluorescent protein) transgenic mice depicting nerve MD function, and S100-GFP (green fluorescent protein) transgenic mice reflecting TSC status will elucidate the role of BI-induced nerve MD and TSC changes to MW. Specific Aim 2 tests the hypothesis that α7AChRs play a protective role in maintenance of NMJ integrity by modulating aberrant inflammatory responses, MD, and impaired Akt/GSK-3ß signaling of BI. At fixed time points based on Specific Aim 1 results, morphological and functional changes at NMJ will be studied in wild type and α7AChR knockout mice during early injury-phase and later recovery-phase of BI. Specific Aim 3 tests the hypothesis that treatment with GTS-21, a specific agonist of α7AChRs, will mitigate synaptic and nerve terminal changes of BI. The functional and morphological changes, the specificity and signaling pathways mediating beneficial effects of GTS-21 will also be elucidated. These studies will characterize the NMJ changes of BI, their relationship to MW, and pivotal protective role of α7AChRs in NMJ integrity. Therapeutics with GTS-21 via a7AChRs stimulation is an untested novel approach to restore synaptic, and nerve terminal changes and MW of BI.

 描述（由适用提供）：烧伤损伤（BI）导致神经肌肉功能障碍（NMD）和肌肉无力（MW）。 BI后，运动神经末端和合成变化与MW的关系尚不清楚。 Integrity of neuromuscular junction (NMJ) depends on tropic signals from nerve to muscle mediated via synthetic acetylcholine receptors (AChRs), and on retrograde cues from muscle including pivotal signaling via Akt (a.k.a., PKB) and glycogen synthase kinase-3ß (GSK-3ß) to synapse.末端Schwann细胞（TSC）功能对于NMJ完整性也是必不可少的。我们肯定，NMJ组织钝性的热带信号传导的BI和线粒体功能障碍（MD）的炎症反应以及TSC功能导致神经和突触的演变，这些演变对于NMD和MW是核心。主要的挑战是如何有效扭转炎症反应介导的NMJ变化。 TSC组成性地表达α7ACHRS同工型，肌肉在BI后上调α7ACHR。发表了，我们的新数据表明，α7ACHR被特定的激动剂GTS-21刺激，可缓解炎症反应，MD，并通过AKT/GSK-3ß增强信号传导。所检验的假设是，通过其多功能作用，用α7ACHR的GTS-21刺激将保护BI小鼠的NMJ变化。具体目标1检验了BI的合成和神经像差导致NMD和MW的假设。使用Thy1-YFP（黄色荧光蛋白）转基因小鼠（描述运动神经）和荧光 - 甲状腺毒素来标记合成ACHR，BI后时间依赖性神经和合成形态变化，以及它们与肌肉功能（张力和疲劳性）的关系。使用描绘神经MD功能的THY1-MITO CFP（CYAN荧光蛋白）转基因小鼠以及反映TSC状态的S100-GFP（绿色荧光蛋白）的转基因小鼠，将阐明双诱导的神经诱导的神经MD和TSC变化的作用。具体目标2检验了α7ACHRS通过调节异常炎症响应，MD和BI的AKT/GSK-3ß信号受损而在维持NMJ完整性中起保护作用的假设。在基于特定目标1结果的固定时间点，在早期损伤相和后来的BI恢复相过程中，将研究NMJ的形态和功能变化。具体目标3检验了以下假设：α7ACHRS的特定激动剂GTS-21的治疗将减轻BI的突触和神经末端变化。功能和形态变化，介导GTS-21有益作用的特异性和信号通路也将得到阐明。这些研究将表征BI的NMJ变化，它们与MW的关系以及α7ACHRS在NMJ完整性中的关键保护作用。通过A7ACHRS刺激使用GTS-21的疗法是一种未经测试的新型方法，用于恢复BI的突触和神经末端变化和MW。