Isoform-specific Roles of Extracelluar-signal Regulated Kinases in Pain

描述(由申请人提供)： 该项目的长期目标是阐明慢性疼痛背后的特定分子和细胞机制。了解这些机制将指导新药和治疗策略的开发，以更好地治疗这一普遍存在的公共卫生负担。这项建议验证了一种假说，即密切相关的细胞外信号调节激酶(ERK)亚型ERK1和ERK2在慢性疼痛中发挥着不同的功能作用。药理学实验表明，ERK1和/或ERK2对于在病理性疼痛的啮齿动物模型中观察到的行为是必要的。为了测试ERK1在这些模型中是否对行为敏化是必要的，我将比较常规ERK1基因敲除小鼠和野生型小鼠的行为反应。不幸的是，传统的ERK2基因敲除小鼠在发育过程中死亡，阻碍了它们在行为实验中的应用。然而，对缺乏ERK1的小鼠的行为分析将提供关于ERK2功能的有价值的信息，因为我们从药理学研究中知道ERK1和/或ERK2参与其中。使用相同药理学工具的研究表明，ERK1/2对于脊髓背角神经元的敏化是必要的，这可能有助于疼痛模型中的行为敏化。为了测试在这些细胞变化中每个个体亚型的必要性，我将在脊髓背角原代培养中消除任何一个亚型。然后，我将确定这些神经元是否发生了与敏化相关的细胞可塑性变化。敏感化也发生在疼痛神经轴的其他部位。在疼痛模型中，传递外周伤害性刺激的伤害性感受器是敏化的，ERK1和/或ERK2参与了这一过程。初步结果表明，ERK1基因敲除小鼠在炎性疼痛模型中表现出与野生型小鼠相似的反应，这部分依赖于伤害性感受器的敏化。为了验证ERK2对于伤害性感受器敏化是必需的这一假设，我将创建一个条件性伤害性感受器特异性ERK2基因敲除，并在炎症性疼痛模型中测试这只小鼠的行为反应。这些实验将是第一次解决ERK1和ERK2在疼痛中的异构体特异性作用。这一提议的结果将为深入了解慢性疼痛的细胞和分子机制提供依据。

DESCRIPTION (provided by applicant): The long-term goal for this project is to elucidate the specific molecular and cellular mechanisms that underlie chronic pain. Understanding these mechanisms will guide the development of new drugs and treatment strategies to better treat this pervasive public health burden. This proposal tests the hypothesis that closely related extracellular-signal regulated kinase (ERK) isoforms, ERK1 and ERK2, play distinct functional roles in chronic pain. Pharmacological experiments indicate that ERK1 and/or ERK2 are necessary for behaviors observed in well-characterized rodent models of pathological pain. To test if ERK1 is necessary for behavioral sensitization in these models, I will compare the behavioral responses of conventional ERK1 knockout mice with wildtype littermates. Unfortunately, conventional ERK2 knockout mice die during development, preventing their use in behavioral experiments. Nevertheless, the behavioral analysis of mice lacking ERK1 will provide valuable information about the function of ERK2, since we know from pharmacological studies that ERK1 and/or ERK2 is involved. Studies using the same pharmacological tools indicate that ERK1/2 is necessary for the sensitization of spinal cord dorsal horn neurons, which is likely to contribute to behavioral sensitization in pain models. To test the necessity of each individual isoform in these cellular changes, I will eliminate either isoform in spinal cord dorsal horn primary cultures. I will then determine whether cellular plasticity changes associated with sensitization occur in these neurons. Sensitization also occurs elsewhere in the pain neuraxis. Nociceptors, which transduce peripheral noxious stimuli, are sensitized in pain models, and ERK1 and/or ERK2 have been implicated in this process. Preliminary results indicate that ERK1 knockout mice show responses similar to those of wildtype littermates in inflammatory pain models, which partially depend on nociceptor sensitization. To test the hypothesis that ERK2 is necessary for nociceptor sensitization, I will create a conditional nociceptor-specific ERK2 knockout and test the behavioral responses of this mouse in models of inflammatory pain. These experiments will be the first to address the isoform-specific roles of ERK1 and ERK2 in pain. Results from this proposal will provide insight into the cellular and molecular mechanisms of chronic pain.