Identifying novel proteins in injured nerves that promote functional regeneration

越来越明显的是，周围神经系统(PNS)中的雪旺细胞(SCs)作为一个单位发挥作用 用神经元来调节感觉功能。当三叉神经核受损时，干细胞被激活以进行修复。这 涉及戏剧性的SC表型转变。如果这一过程异常或被抑制，周围神经进入- 陪审团可能导致慢性衰弱疼痛，这是在普通人群中观察到的问题，包括许多 退伍军人。慢性神经性疼痛的治疗选择有限。与许多其他调查人员不同的是 SC领域，我们假设，作为对损伤的反应，SC的激活在不同的细胞之间是不同的，所以一个细胞- 少量的SC活化态共存。我们还假设SC维修计划可能会扩大 从治疗上改善结果。这项研究项目的主要目标是确定我们是否可以 靶向SC低密度脂蛋白受体相关蛋白-1(LRP1)，我们已经确定一个受体在 激活SC，以改善周围神经损伤后的疼痛结果。为了实现我们的目标，我们有三个目标-- 提出了科学的目标。在具体目标1中，我们将应用先进的转录组分析技术和 现在“在手”SC特定的RiboTag小鼠模型，以测试SC激活发生在一系列 步骤，并可在治疗上增强。这个目标的核心是我们发现特定的LRP1配体 能够进一步激活对SC修复计划至关重要的关键细胞信号通路。我们 假设这些配体可能是改善PNS损伤后结果的候选者。具体而言 目标2，我们的目标是发现自然存在于坐骨神经中的新的LRP1配体，主要是在 受伤，因此可能有助于激活SC修复计划。这一基于发现的目标适用于 成熟的捕获技术和LC-MS/MS我们已经开始在受伤的人身上鉴定新的配体 神经，包括Pacsin1和Decorin，将在验证实验中进行分析。我们的持续工作 应该揭示更多的配基，这些配基也将使用体外生物测定来确定最佳的CaN- 决定过渡到翻译研究。在特定的目标3中，我们将测试LRP1与 最佳属性(在特定目标2中确定)可改善小鼠三叉神经节损伤后的结果，因为它阻止- 通过测量诱发的和自发的疼痛来挖掘。我们将研究两类LRP1配体。第一, 损伤神经中发现的可能作为内源性SC LRP1激活剂的LRP1配体将被研究。 其次，我们建议检查已知的LRP1配体，这些配体已被基因工程改造为捕获 有利的活动，同时消除不利的偏离目标的影响。AIM中提出的实验 3是合理的，已发表的研究表明，当小鼠干细胞中的LRP1被删除时，疼痛相关行为 在野生型小鼠中的研究表明，SC LRP1的活性在体内可能会增强。我们 认为这个项目是创新的，因为我们针对的是干细胞，而不是神经元来治疗慢性疼痛。这项工作是 翻译性，因为它有极好的机会来改善我们VA患者的慢性疼痛管理。

It is increasingly apparent that Schwann cells (SCs) in the peripheral nervous system (PNS) function as a unit with neurons to regulate sensory function. When the PNS is injured, SCs become activated for repair. This involves dramatic SC phenotypic transformation. If this process is abnormal or inhibited, peripheral nerve in- jury may result in chronic debilitating pain, a problem observed in the general population, including numerous Veterans. Treatment options for chronic neuropathic pain are limited. Unlike many other investigators in the SC field, we hypothesize that in response to injury, SC activation is variable from cell to cell so that a con- tinuum of SC activation states co-exist. We also hypothesize that the SC Repair Program may be augmented therapeutically to improve outcomes. The major goal of this research project is to determine whether we can target SC LDL Receptor-related Protein-1 (LRP1), a receptor that we have identified as playing a central role in SC activation, to improve pain outcomes following peripheral nerve injury. To accomplish our goals, three spe- cific aims are proposed. In Specific Aim 1, we will apply advanced transcriptome profiling technology and a now “in hand” SC-specific RiboTag mouse model to test the hypothesis that SC activation occurs in a series of steps and may be augmented therapeutically. Central to this Aim is our discovery that specific LRP1 ligands are capable of further activating key cell-signaling pathways that are essential to the SC Repair Program. We hypothesize that these ligands may be candidates for improving outcomes following PNS injury. In Specific Aim 2, our goal is to discover novel LRP1 ligands that are naturally present in the sciatic nerve, mainly after injury, and thus may contribute to activation of the SC Repair Program. This discovery-based Aim applies established capture technology and LC-MS/MS. We have already begun to identify novel ligands in the injured nerve, including Pacsin1 and Decorin, which will be analyzed in validation experiments. Our continuing work should reveal additional ligands that also will be validated using in vitro bioassays to determine optimal can- didates to transition into translational studies. In Specific Aim 3, we will test whether LRP1 ligands with optimal properties (as determined in Specific Aim 2) improve outcomes following PNS injury in mice, as deter- mined by measuring evoked and spontaneous pain. Two categories of LRP1 ligands will be studied. First, LRP1 ligands identified in injured nerves, which may serve as endogenous SC LRP1 activators, will be studied. Second, we propose to examine known LRP1 ligands that have been genetically engineered to capture advantageous activities while eliminating disadvantageous off-target effects. The experiments proposed in Aim 3 are justified by published studies showing that when LRP1 is deleted in SCs in mice, pain-related behaviors increase and by studies in wild-type mice showing that SC LRP1 activity may be augmented in vivo. We consider this project innovative because we target SCs, instead of neurons to treat chronic pain. This work is translational in that it has excellent opportunity to improve management of chronic pain for our VA patients.