Dual specificity phosphatases and MAP kinase signaling

描述（由申请人提供）：本修订提案的广泛，长期目标是描述双特异性磷酸酶（dsp）调节MAP激酶依赖性信号转导的新方面。JNKs是MAP激酶的一个亚组，在对促炎细胞因子和环境应激的反应中被激活，并参与增殖和凋亡的调节。它们被认为是治疗几种主要人类疾病的治疗靶点，包括癌症、炎症以及神经退行性和代谢性疾病。与迄今为止的研究集中在通过dsp下调JNK信号传导的研究相反，大量的初步数据显示，2种dsp， JSP1 （JNK刺激磷酸酶1）和密切相关的酶DSP18/JSP2，具有增强JNK激活的潜力。拟议研究的目的是确定这些dsp在JNK通路调控中的作用，验证它们可能作为JNK信号反应特异性决定因素的假设。具体目的是：(1)在细胞模型中分析改变JSP1表达对细胞信号传导的影响，包括使用RNA干扰。(2)对JSP1进行结构功能分析，重点鉴定其生理底物。(3)对JSP1的近亲DSP18进行表征，确定其是否也具有JNK信号的调节作用。(4)通过分析JSP1基因敲除小鼠的表型，分析JSP1基因敲除小鼠的组织和细胞中JNK信号的表达，来表征JSP1的功能。这项研究的健康相关性在于潜在的治疗意义。jnk被认为是几种主要人类疾病的治疗靶点。大量的JNK异构体，以及它们在多种细胞功能中的重要性，表明设计用于直接在活性位点抑制JNK的药物可能会发挥广泛的作用，从而限制了它们的效用。相反，如果JSP1或DSP18/JSP2被证明调节特定JNK亚型的激活或在特定刺激下激活JNK，那么这些dsp的抑制剂可能在更有限的环境中减弱JNK信号，可能增强其治疗潜力。

DESCRIPTION (provided by applicant): The broad, long-term objectives of this revised proposal are to characterize a novel aspect of the regulation of MAP kinase-dependent signal transduction by dual specificity phosphatases (DSPs). The JNKs are a subgroup of the MAP kinases that are activated in response to pro-inflammatory cytokines and environmental stresses and are implicated in the regulation of proliferation and apoptosis. They are recognized as therapeutic targets for treatment of several major human diseases including cancer, inflammation, as well as neurodegenerative and metabolic diseases. In contrast to studies to date that have focused on the downregulation of JNK signaling by DSPs, extensive preliminary data are presented showing that 2 DSPs, JSP1 (Jnk Stimulatory Phosphatase 1) and the closely related enzyme DSP18/JSP2, have the potential to augment the activation of JNK. The objective of the proposed studies is to define the role of these DSPs in regulation of the JNK pathway, testing the hypothesis that they may function as determinants of specificity in JNK signaling responses. The Specific Aims are: (1) To analyze the effects on cell signaling of altering expression of JSP1 in cell models, including the use of RNA interference. (2) To conduct a structure-function analysis of JSP1, focusing on the identification of its physiological substrates. (3) To characterize DSP18, the closest relative of JSP1, to determine whether it also functions as a regulator of JNK signaling. (4) To characterize the function of JSP1 through analysis of the phenotype of JSP1 knockout mice and analysis of JNK signaling in tissues and cells derived from these mice. The health relatedness of this research lies in the potential therapeutic implications. The JNKs are recognized as therapeutic targets for several major human diseases. The large number of JNK isoforms, together with their importance in a wide variety of cell functions, suggests that drugs designed to inhibit the JNKs directly at the active site may exert broad-ranging effects thereby limiting their utility. In contrast, if JSP1 or DSP18/JSP2 are shown to regulate the activation of specific JNK isoforms or to activate JNK in response to specific stimuli, an inhibitor of these DSPs may attenuate JNK signaling in a more restricted context, possibly enhancing its therapeutic potential.