Small Molecules to Promote Regeneration and Recovery Following Spinal Cord Injury

A.摘要 脊髓损伤（SCI）后改善预后的一个重要障碍是脊髓损伤后有限的轴突损伤。 由于损伤部位的轴突纤维再生不足而导致再生。RhoA介导的信号传导 GTPPases是增长的一个重大障碍。迄今为止，还没有小分子RhoA拮抗剂 已经显示出体内功效。这归因于小GTP酶如RhoA不具有可药物化的功能。 口袋，使得直接与它们结合的小分子的开发极其困难。但在 近年来，已经发现了几种具有可药用口袋的蛋白质与RhoA相互作用。我们规定 与这些药物靶点结合的小分子将促进轴突再生和恢复到正常水平。 类似于或大于直接抑制RhoA活性的程度。为了鉴定这些化合物，我们采用了一种独特的 一种方法，包括基于结构的大型化学库与可药物靶点的计算对接 与RhoA相互作用。我们测试了前50-100种化合物对神经突生长和轴突生长的影响。 再生一种化合物，RLA-47，抑制体外神经突生长和轴突再生。的 化合物在脊髓损伤的动物模型中也显示出大量的轴突交叉。我们的中央 假设RLA-47及其衍生物将促进脊髓损伤后轴突再生和恢复， 损伤我们的初步数据使我们处于一个强有力的位置来验证我们的假设。在我们的第一个目标中，我们建议 设计和合成RLA-47的衍生物，将在我们的神经突生长和轴突再生中进行测试 体外测定。最有希望的候选人将在我们的体内脊髓半切模型中探索 损伤在我们的第二个目标中，我们建议开发具有合适的药代动力学和血液动力学的RLA-47衍生物。 脑渗透性，促进轴突再生体内。我们还测试了最有前途的化合物， 一种更符合临床的脊髓损伤挫伤模型。我们将使用标准的化学生物学策略 亲和纯化和质谱分析，以揭示RLA-47及其衍生物的靶点。沿着RNA 测序，这些研究将提供更深入的了解化合物的作用机制。我们预计 1-2 RLA-47的衍生物表现出上级的药代动力学、脑渗透性和功效。这些 化合物将导致研究性新药申请，我们预计最终将导致候选人， 在临床试验中单独探索，或与其他疗法联合使用，以促进再生， 脊髓损伤患者的康复。

A. ABSTRACT A significant impediment towards improvement of outcome after spinal cord injury (SCI) is the limited axonal regeneration due to insufficient regrowth of the axonal fibers at the lesion site. Signaling mediated by RhoA GTPases presents a significant impediment to growth. To date, there exists no small-molecule RhoA antagonists that have shown in vivo efficacy. This is attributed to the fact that small GTPases like RhoA do not have druggable pockets, making the development of small molecules that directly bind to them extremely difficult. However, over the years, several proteins with druggable pockets have been discovered to interact with RhoA. We stipulated that small molecules that bind to these druggable targets will promote axonal regeneration and recovery to a similar or greater extent than direct inhibition of RhoA activity. To identify such compounds we pursued a unique approach that consisted of structure-based computational docking of large chemical libraries to druggable targets that interact with RhoA. We tested the top 50-100 compounds for their effect on neurite outgrowth and axonal regeneration. One compound, RLA-47, inhibited in vitro neurite outgrowth and axonal regeneration. The compound also showed substantial axon crossings in an animal model of spinal cord injury. Our central hypothesis is that RLA-47 and its derivatives will promote axonal regeneration and recovery following spinal cord injury. Our preliminary data puts us in a strong position to test our hypothesis. In our first aim, we propose to design and synthesize derivatives of RLA-47 that will be tested in our neurite outgrowth and axonal regeneration in vitro assays. The most promising candidates will be explored in our in vivo hemisection model of spinal cord injury. In our second aim, we propose to develop RLA-47 derivatives with suitable pharmacokinetics and blood- brain permeability that promote axonal regeneration in vivo. We also test the most promising compounds using a more clinically relevant contusion model of spinal cord injury. We will use a standard chemical biology strategy of affinity purification and mass spectrometry to uncover targets of RLA-47 and its derivatives. Along with RNA sequencing, these studies will provide deeper insight into the mechanism of action of compounds. We expect 1-2 derivatives of RLA-47 to exhibit superior pharmacokinetics, brain permeability and efficacy. These compounds will lead to investigational new drug filing that we expect will eventually lead to candidates that can be explored in clinical trials either alone, or in combination with other therapies to promote regeneration and recovery in spinal cord injury patients.