Genetic and Pharmacological Validation of CRMP2 Phosphorylation as a Novel therapeutic Target for Neuropathic Pain

摘要 有效治疗高冲击性疼痛患者是国家疼痛协会宣布的主要目标之一 战略。识别神经病理性疼痛的新靶点和机制将是至关重要的 开发新的靶向药物，以更好地管理神经病理性疼痛。我们最近 发现周围神经损伤诱导轴突引导磷蛋白崩解上调 反应介质蛋白2(CRMP2)和N型电压门控钙(Cav2.2)以及Nav1.7 电压门控钠通道通过不明原因与神经病理性疼痛的发生相关 机制。在我们的初步研究中，我们发现干扰CRMP2的磷酸化状态是 足以提供对慢性疼痛的保护。其他人发现，CRMP2基因敲入突变小鼠 丙氨酸使Ser522磷酸化位点失活(Crmp2S522A)的敏感度降低 为了痛苦。CRMP2磷酸化的预防和对失调的影响之间的机制联系 神经病理性疼痛处理过程中的兴奋性突触传递从未被研究过。 是否存在允许CRMP2在假定的非 磷酸化(非疼痛)和磷酸化(疼痛)状态尚不清楚。我们发现， PCRMP2：CRMP2在人的脊髓中有不同的表达。根据文献和我们的初步数据，我们 假设损伤诱导了磷酸化的CRMP2/Cav2.2和磷酸化的CRMP2/Nav1.7 感觉通路上调促进脊髓异常兴奋性突触传递 会导致神经病理性疼痛状态。在目标1中，我们将确定潜在的分子/细胞机制 CRMP2异常兴奋性突触传递与神经病理性疼痛处理 磷酸化被抑制。在目标2中，我们将尝试直接解决NIH帮助结束长期成瘾的问题- 加速科学解决国家阿片类药物公共卫生危机的长期倡议：(A) 确定靶向CRMP2磷酸化的副作用和滥用倾向 分子，以及(B)确定含有小分子的CRMP2是否可以减少阿片类药物滥用或减少阿片类药物滥用 责任。我们建议验证CRMP2磷酸化作为神经病理性疼痛的新靶点。 创新工具，包括遗传方法(Crmp2S522A)小鼠以及非阿片类药物 方法(一种新的CRMP2-磷酸化靶向化合物)。此应用程序的预期结果为 翻译上的重大意义在于，他们将CRMP2磷酸化确立为一种新的止痛药 目标。通过证明抑制CRMP2的磷酸化可以逆转或预防神经病理性疼痛，我们 将促进一个新的治疗靶点(CRMP2-磷酸化)的发现和验证，以促进 开发新的止痛疗法--从而直接满足RFA-NS-18-043的要求。

SUMMARY Effective treatment of high-impact pain patients is one of the major stated goals of the National Pain Strategy. Identification of new targets and mechanisms underlying neuropathic pain will be critical in developing new target-specific medications for better neuropathic pain management. We recently discovered that peripheral nerve injury-induced upregulation of an axonal guidance phosphoprotein collapsin response mediator protein 2 (CRMP2) and the N-type voltage-gated calcium (CaV2.2) as well as the NaV1.7 voltage-gated sodium channel, correlates with the development of neuropathic pain through an unidentified mechanism. In our preliminary studies, we found that interfering with the phosphorylation status of CRMP2 is sufficient to confer protection from chronic pain. Others have found that a CRMP2 knock-in mutant mouse where the phosphorylation site Ser522 was inactivated with alanine (crmp2S522A) had a decreased sensitivity to pain. A mechanistic link between prevention of CRMP2 phosphorylation and effects on dysregulated excitatory synaptic transmission underlying neuropathic pain processing has never been investigated. Whether there is a phosphoregulatory “set-point” permitting CRMP2 to “toggle” between a presumptive non- phosphorylated (non-pain) and phosphorylated (pain) state is not known. We find that the ratio of pCRMP2:CRMP2 varies in human spinal cords. Based on the literature and our preliminary data, we hypothesize that injury induced phosphorylated-CRMP2/CaV2.2 and phosphorylated-CRMP2/NaV1.7 upregulation in the sensory pathway promotes abnormal excitatory synaptic transmission in spinal cord that leads to neuropathic pain states. In Aim 1, we will determine the molecular/cellular mechanisms underlying aberrant excitatory synaptic transmission and neuropathic pain processing in conditions wherein CRMP2 phosphorylation is inhibited. In Aim 2, we will attempt to directly tackle NIH's Helping to End Addiction Long- term (HEAL) initiative to speed scientific solutions to the national opioid public health crisis by: (a) determining the side-effect profile and abuse liability of targeting CRMP2 phosphorylation with a small molecule, and (b) determine if CRMP2 with a small molecule can be opioid sparing or decrease opioid abuse liability. We propose to validate CRMP2 phosphorylation as a novel target in neuropathic pain using innovative tools that include a genetic approach (crmp2S522A) mice as well as a non-opioid pharmacological approach (a novel CRMP2-phsphorylation targeting compound). The expected results of this application are translationally significant in that they will establish CRMP2-phosphorylation as a novel pain therapeutic target. By demonstrating that inhibition of CRMP2 phosphorylation reverses or prevents neuropathic pain, we will promote the discovery and validation of a novel therapeutic target (CRMP2-phosphorylation) to facilitate the development of novel pain therapeutics – thus directly addressing the mandate of RFA-NS-18-043.