Targeting Endosomal Receptors for Treatment of Chronic Pain

项目总结/摘要 药物治疗常见形式的慢性疼痛是无效的，并受到副作用的困扰。我们长久以来- 长期目标是揭示疼痛/伤害性信号传导的机制并定义药物靶点。g蛋白偶联 受体（GPCR）控制大多数病理生理过程，包括疼痛，并且是34%的 治疗药物GPCR被认为仅在质膜上起作用，在质膜上它们与 细胞外配体并与细胞内G蛋白偶联。然而，从损伤和 患病组织引起GPCR向神经元内体的再分布。这些内体GPCR （eGPCR）在控制离子通道活性的亚细胞区室中产生持续的信号， 是慢性疼痛的基础核心假设是，原伤害感受eGPCR的激活产生了 伤害性信号传导和大多数形式的慢性疼痛; eGPCR的拮抗剂阻断伤害性信号传导， 是抗伤害的这一提议的基本原理是，eGPCR疼痛机制的发现将促进 开发选择性拮抗神经元中的eGPCR并提供上级疼痛缓解的药物， 更少的副作用。总体目标是发现慢性疼痛的潜在机制，并验证 治疗靶点中心假设将通过追求三个具体目标进行测试：1）发现 神经元亚细胞区室中eGPCR信号传导的机制;生物物理和成像 纳米粒子（NPs）将被设计成具有靶向神经元的成分， 内吞作用并在酸性内体中释放eGPCR配体; 2）发现 eGPCR调节控制神经元活性的离子通道;离子通道活性和神经元的兴奋性将 进行电生理学研究。NP包封的药物探针将定义eGPCR在神经元中的作用。 兴奋; 3）验证eGPCR作为慢性炎症性、神经性和癌症疼痛的治疗靶点; 将在三种疼痛模型中将NP包封的eGPCR配体与常规疗法进行比较。的 提出的疼痛机制是一种新的解释，解决了广泛的临床试验失败的谜团， GPCR靶向药物。该提案的创新之处在于扩展到NP方法来探索机制， 确认目标该提案具有临床意义，因为它验证了eGPCR靶点， 上级止痛效果好，副作用少，适用于大多数顽固性慢性疼痛患者。

PROJECT SUMMARY/ABSTRACT Pharmacologic therapy for common forms of chronic pain is ineffective and plagued with side effects. Our long- term goal is to reveal mechanisms of pain/nociceptive signaling and define drug targets. G protein-coupled receptors (GPCRs) control most patho-physiological processes, including pain, and are the target of 34% of therapeutic drugs. GPCRs are considered to function solely at the plasma membrane, where they interact with extracellular ligands and couple to intracellular G proteins. However, agonists released from injured and diseased tissues evoke redistribution of GPCRs to endosomes in neurons. These endosomal GPCRs (eGPCRs) generate sustained signals in subcellular compartments that control the ion channel activity that underlies chronic pain. The central hypothesis is that activation of pronociceptive eGPCRs produces nociceptive signaling and most forms of chronic pain; antagonists of eGPCRs block nociceptive signaling and are anti-nociceptive. The rationale for this proposal is that discovery of eGPCR pain mechanisms will facilitate development of drugs that selectively antagonize eGPCRs in neurons and provide superior pain relief with fewer side effects. The overall objectives are to discover mechanisms underlying chronic pain and validate a therapeutic target. The central hypothesis will be tested by pursuing three specific aims: 1) Discover the mechanisms of eGPCR signaling in subcellular compartments of neurons; biophysical and imaging approaches will be used; nanoparticles (NPs) will be designed with components that target neurons, promote endocytosis and release eGPCR ligands in the acidic endosome; 2) Discover the mechanisms by which eGPCRs regulate ion channels that control neuron activity; ion channel activity and excitability of neurons will be studied with electrophysiology. NP-encapsulated drug probes will define the role of eGPCRs in neuronal excitation; 3) Validate eGPCRs as a therapeutic target for chronic inflammatory, neuropathic and cancer pain; NP-encapsulated eGPCR ligands will be compared to conventional therapy in three pain models. The proposed pain mechanism is a novel explanation that resolves the enigma of widespread clinical trial failures of GPCR-targeted drugs. Innovation in the proposal extends to the NP approach to probe the mechanism and validate the target. The proposal is clinically significant because it validates an eGPCR-target that offers superior pain relief with fewer side-effects and is applicable to most patients with intractable chronic pain.