Neuron-specific block of T-type calcium channels

描述（由申请人提供）：疼痛是美国的主要健康问题，十分之一的美国人患有中度至重度疼痛。然而，慢性疼痛的治疗仍然是一个临床挑战，只有一半的患者得到充分的疼痛缓解。因此，开发无滥用潜力和副作用的新型镇痛药将对疼痛治疗产生重大影响。指导这些探索性研究的假设是，慢性疼痛可以通过抑制伤害感受器中的离子通道如Cav3.2 T型电压门控钙通道来治疗。 在慢性缩窄性神经损伤和糖尿病性神经病变的动物模型中，T电流上调，并且Cav3.2定向的反义寡核苷酸逆转在这些动物中观察到的机械性痛觉过敏和异常性疼痛。 重要的是，Cav3.2对于啮齿类动物和人类的疼痛信号传导都很重要，因为临床相关的镇痛剂硫辛酸在体外阻断人Cav3.2电流，但在体内Cav3.2敲除小鼠中无效。这些研究将开发短发夹RNA（shRNA），抑制小鼠和人类Cav3.2通道的表达。与化学合成的siRNA相反，基于DNA的shRNA的递送可以使用基因启动子特异性靶向神经元亚型。本研究将探讨使用钠通道启动子Scn10a，其表达主要限于伤害感受器。临床应用的一个重要特征是调节基因治疗的能力。这将使用新开发的四环素阻遏物版本来完成，其需要药物来激活（强力霉素-ON）。重组腺相关病毒（rAAV）已成为人类基因治疗的首选。AAV颗粒可以产生具有蛋白质外壳的，其有效地感染感觉神经元并被逆行转运到细胞核（例如血清型8）。这些研究的目标是开发指导shRNA介导的Cav3.2敲低的rAAV靶向载体，用其制备病毒颗粒，然后在患有神经性疼痛的大鼠中测试伤害感受器特异性表达.该研究团队包括T通道专家Edward Perez-Reyes博士，AAV专家Guanping Gao博士和神经性疼痛专家Hui-Lin Pan博士。 慢性疼痛影响超过10%的人口，导致生产力和生活质量下降。目前的建议集中在开发一种新的疼痛治疗方法，可以提供长期治疗而没有滥用的可能性。 免责声明：请注意，以下评论是由审查员在研究部分会议之前准备的，并且以基本上未经编辑的形式提供。 虽然审查人员有机会根据小组讨论情况更新或修订其书面评价，但不能保证在会议讨论之后更新了个人评论。 因此，这些评论可能并不完全反映小组讨论结束时单个评审员的最终意见或小组的最终多数意见。因此，讨论的简历和摘要是评审员在会议上实际认为关键的最后一句话。

DESCRIPTION (provided by applicant): Pain is a leading health problem in the United States with 1 in 10 Americans suffering from moderate to severe pain. Yet, the treatment of chronic pain remains a clinical challenge, with only half of patients receiving adequate pain relief. Therefore, the development of novel analgesics without abuse potential and side effects would have significant impact on the treatment of pain. The hypothesis guiding these exploratory studies is that chronic pain can be treated by inhibiting ion channels in nociceptors such as the Cav3.2 T-type voltage-gated calcium channel. T-currents are upregulated in animal models of chronic constrictive nerve injury and diabetic neuropathy, and Cav3.2 directed antisense oligonucleotides reverse the mechanical hyperalgesia and allodynia observed in these animals. Importantly, Cav3.2 is important for pain signaling in both rodents and humans, since the clinically relevant analgesic, lipoic acid, blocks human Cav3.2 currents in vitro yet is ineffective in Cav3.2 knockout mice in vivo. These studies will develop short hairpin RNAs (shRNA) that inhibit the expression of mouse and human Cav3.2 channels. In contrast to chemically synthesized siRNA, delivery of DNA-based shRNA can be specifically targeted to neuronal subtypes using gene promoters. The present study will explore the use of the sodium channel promoter Scn10a, whose expression is largely limited to nociceptors. An important feature for clinical use is the ability to regulate gene therapy. This will be accomplished using a newly developed version of the tetracycline repressor, which requires drug for activation (doxycycline-ON). Recombinant adeno-associated virus (rAAV) has emerged as the top choice for human gene therapy. AAV particles can be produced with protein coats that effectively infect sensory neurons and are retrogradely transported to the nucleus (e.g. serotype 8). The goal of these studies is to develop rAAV targeting vectors that direct shRNA- mediated knockdown of Cav3.2, use this to prepare viral particles, and then test for nociceptor- specific expression in rats with neuropathic pain. The research team includes Dr. Edward Perez- Reyes, a T-channel expert, Dr. Guanping Gao, an AAV expert, and Dr. Hui-Lin Pan, a neuropathic pain expert. PUBLIC HEALTH RELEVANCE: Project Narrative Chronic pain affects over 10% of the population, resulting in lowered productivity and quality of life. The present proposal is focused on developing a novel treatments of pain that can provide long-term treatment without abuse potential. Disclaimer: Please note that the following critiques were prepared by the reviewers prior to the Study Section meeting and are provided in an essentially unedited form. While there is opportunity for the reviewers to update or revise their written evaluation, based upon the group's discussion, there is no guarantee that individual critiques have been updated subsequent to the discussion at the meeting. Therefore, the critiques may not fully reflect the final opinions of the individual reviewers at the close of group discussion or the final majority opinion of the group. Thus the Resume and Summary of Discussion is the final word on what the reviewers actually considered critical at the meeting.