Dual specificity phosphatases and MAP kinase signaling

描述（由申请人提供）：本修订提案的广泛、长期目标是表征双特异性磷酸酶（DSP）调节MAP激酶依赖性信号转导的新方面。JNK是MAP激酶的一个亚组，其响应于促炎细胞因子和环境应激而被激活，并且涉及增殖和凋亡的调节。它们被认为是治疗几种主要人类疾病的治疗靶标，包括癌症、炎症以及神经退行性和代谢性疾病。与迄今为止专注于DSP下调JNK信号传导的研究相反，提供了大量的初步数据，表明2种DSP，JSP 1（JNK刺激磷酸酶1）和密切相关的酶DSP 18/JSP 2，具有增强JNK激活的潜力。提出的研究的目的是确定这些DSP在JNK通路的调节中的作用，测试它们可能作为JNK信号传导反应特异性的决定因素的假设。具体目标是：（1）在细胞模型中分析改变JSP 1表达对细胞信号传导的影响，包括使用RNA干扰。(2)对JSP 1进行结构-功能分析，重点是鉴定其生理底物。(3)为了表征DSP 18，JSP 1的最近亲属，以确定它是否也作为JNK信号转导的调节器。(4)通过分析JSP 1基因敲除小鼠的表型以及这些小鼠组织和细胞中JNK信号转导的分析来表征JSP 1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同种型，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的药物可能发挥广泛的作用，从而限制了它们的效用。相反，如果JSP 1或DSP 18/JSP 2显示出调节特定JNK同种型的活化或响应于特定刺激而活化JNK，则这些DSP的抑制剂可以在更受限的情况下减弱JNK信号传导，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.