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，以更好地治疗这种普遍的公共卫生负担。该提议检验了密切相关的细胞外信号调节激酶（ERK）亚型ERK 1和ERK 2在慢性疼痛中发挥不同功能作用的假设。药理学实验表明，ERK 1和/或ERK 2是必要的行为观察到的特征良好的啮齿动物模型的病理性疼痛。为了测试ERK 1是否是这些模型中行为敏化所必需的，我将比较传统ERK 1敲除小鼠与野生型同窝小鼠的行为反应。不幸的是，传统的ERK 2基因敲除小鼠在发育过程中死亡，阻止了它们在行为实验中的应用。然而，缺乏ERK 1的小鼠的行为分析将提供有关ERK 2功能的有价值的信息，因为我们从药理学研究中知道ERK 1和/或ERK 2参与其中。使用相同的药理学工具的研究表明，ERK 1/2是脊髓背角神经元敏化所必需的，这可能有助于疼痛模型中的行为敏化。为了测试这些细胞变化中每种亚型的必要性，我将在脊髓背角原代培养中消除任何一种亚型。然后，我将确定这些神经元中是否发生了与致敏相关的细胞可塑性变化。致敏作用也发生在疼痛神经轴的其他部位。在疼痛模型中，伤害性感受器（nociceptor）（其抵抗外周伤害性刺激）被致敏，并且ERK 1和/或ERK 2已被牵涉在该过程中。初步结果表明，ERK 1基因敲除小鼠在炎症性疼痛模型中表现出与野生型同窝小鼠相似的反应，这部分取决于伤害感受器敏化。为了验证ERK 2对于伤害感受器致敏是必要的这一假设，我将创建一个条件性伤害感受器特异性ERK 2敲除，并在炎症性疼痛模型中测试该小鼠的行为反应。这些实验将首次解决ERK 1和ERK 2在疼痛中的亚型特异性作用。从这个建议的结果将提供深入了解慢性疼痛的细胞和分子机制。

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.