FL2 siRNA as a Novel Therapeutic Option to Induce Spinal Cord Regeneration Following Injury

摘要 Fidgetin-like 2（FL 2）是一种微管（MT）调节蛋白，其通过其推定的调节微管（MT）的动力学。 MT切断活性，调节细胞运动和轴突生长和指导。最近，我们发现FL 2是一种 轴突生长的负调节因子，并证明了周围神经损伤后FL 2的靶向耗竭 损伤促进大鼠功能性神经再生。我们的初步研究表明，在损伤后， 在包括脊髓在内的几种成人组织的损伤部位上调。在使用啮齿动物SCI的试点研究中， 在模型中，我们类似地发现，使用FL 2 siRNA包埋的损伤部位的FL 2的局部消耗， 纳米颗粒（SiF 1 2）改善了胸部挫伤后运动和膀胱功能的恢复， 压迫性损伤我们假设FL 2负调控SCI后轴突再生， 脊髓损伤后FL 2的下调将促进功能恢复。我们的目标是用3个具体的假设来检验这个假设。 目标。第一个目标将确定SiFi 2处理后FL 2沉默的程度和持续时间。第二 目的是通过探索后肢运动和感觉来评估SiFi 2治疗对SCI后的功能影响。 SiFi 2给药后的功能。第三个目标是评估脊髓的分子和组织学变化， 通过检查轴突再生、神经胶质瘢痕形成和 来自目标2的脊髓组织中的炎症反应。这些研究将是第一次评估FL 2 调节中枢神经系统（CNS）损伤反应，并首次评估其治疗潜力 使用RNAi瞬时下调FL 2表达，以改善CNS损伤后的功能恢复。 损伤虽然这项建议特别关注SCI作为一种治疗应用，但我们预计数据 从这些研究中产生的影响将具有更广泛的意义，因为它们将表征以前的 未研究的CNS创伤性损伤反应的调节剂，一种可以潜在地靶向增强 再生后广泛的中枢神经系统损伤。

ABSTRACT Fidgetin-like 2 (FL2) is a microtubule (MT) regulatory protein that modulates MT dynamics through its putative MT-severing activity, regulating cell motility and axonal growth and guidance. Recently, we identified FL2 as a negative regulator of axonal growth, and demonstrated that targeted depletion of FL2 following peripheral nerve injury enhances functional nerve regeneration in rats. Our preliminary studies show that following injury FL2 is upregulated at the injury site in several adult tissues including the spinal cord. In pilot studies using rodent SCI models, we similarly found that local depletion of FL2 from the injury site using FL2 siRNA embedded in nanoparticles (SiFi2) improved recovery of locomotor and bladder function after thoracic contusion and compression injury. We hypothesize that FL2 negatively regulates axonal regeneration after SCI, and that downregulation of FL2 after SCI will improve functional recovery. We aim to test this hypothesis with 3 specific aims. The first aim will determine the extent and duration of FL2 silencing following SiFi2 treatment. The second aim will evaluate the functional effects of SiFi2 treatment after SCI by exploring hindlimb locomotor and sensory function after SiFi2 administration. The third aim will evaluate molecular and histological changes at the spinal cord lesion site following SiFi2 treatment by examining axonal regeneration, glial scar formation, and inflammatory response in the spinal cord tissue from Aim 2. These studies will be the first to evaluate FL2 regulation of the central nervous system (CNS) injury response, and the first to assess the therapeutic potential of using RNAi to transiently downregulate FL2 expression in order to improve functional recovery after CNS injury. While this proposal focuses specifically on SCI as a therapeutic application, we anticipate the data generated from these studies will have broader implications as they will characterize the role of a previously unstudied regulator of CNS traumatic injury response, one which can potentially be targeted to enhance regeneration following a wide range of CNS injuries.