The PTP, STEP, Regulates Amphetamine Actions

PTP、STEP 规范安非他明行为

• 批准号: 6820489
• 负责人: Paul J Lombroso
• 金额: $ 35.57万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-15 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6820489
• 关键词: JUN kinase; amphetamines; amygdala; behavioral /social science research tag; behavioral habituation /sensitization; biological signal transduction; corpus striatum; dopamine; fos protein; frontal lobe /cortex; gene expression; genetic regulation; genetically modified animals; glutamates; immunocytochemistry; laboratory mouse; laboratory rabbit; laboratory rat; mitogen activated protein kinase; nucleus accumbens; phosphorylation; protein binding; protein tyrosine phosphatase; western blottings

DESCRIPTION (provided by applicant): Chronic intermittent exposure to stimulant drugs produces persistent and progressive changes in behavior including responses to subsequent drug challenges. This phenomenon is termed sensitization. Although animal models have provided information with regard to the initial biochemical changes involved in sensitazation, less is known about subsequent steps. The present RO1 will investigate this question. Our laboratory has discovered a family of protein tyrosine phosphatases (PTPs) that are expressed within neurons of the CNS. This PTP, termed STEP, is highly enriched in the striatum, nucleus accumbens, amygdala, and the frontal cortices. We recently determined that STEP regulates the activity of the MAP kinase members, ERKI/2. STEP is itself regulated by dopamine and glutamate signaling. Dopamine stimulation leads to the phosphorylation of key regulatory residues and inactivates STEP. Glutamate signaling dephosphorylates and activates STEP. STEP thus acts as a switch that regulates the activity ERK1/2 and limits its ability to activate downstream substrates. We propose that STEP regulates the effects of amphetamine. It does so by controlling the activity of ERKI/2. Consistent with this hypothesis, preliminary data in rats demonstrate that STEP is phosphorylated after amphetamine treatment. The sites phosphorylated are key regulatory residues in a domain required for binding to the ERKs. When STEP is phosphorylated at that site, the ERK signaling cascade is sustained. We will conduct time-course and dose-response analyses with psychostimulants, and perform immunocytochemical and Western blot analyses to determine the patterns of p-ERK, p-STEP, p-CREB, p- Elk-1 and the immediate early genes c-fos, jun and AfosB. We propose that the duration that ERKI/2 remain active determines the pattern of gene expression. Functional studies will disrupt the ability of STEP binding to ERK or disrupt the ability of STEP to let go of ERK. This will be tested by using TAT-peptide technology that introduces protein sequences that either prevent STEP from binding to ERK or never let go of ERK. We show preliminary feasibility data on this approach. A complementary set of experiments will study the STEP knock-out mouse that we predict is hypersensitive to stimulant treatment.

描述（由申请人提供）：长期间歇性接触刺激性药物会导致行为发生持续和渐进的变化，包括对后续药物挑战的反应。这种现象称为敏化。尽管动物模型提供了有关致敏作用的初始生化变化的信息，但对后续步骤知之甚少。 现任RO1将调查这个问题。我们的实验室发现了一个在中枢神经系统神经元内表达的蛋白酪氨酸磷酸酶 (PTP) 家族。这种 PTP，称为 STEP，在纹状体、伏隔核、杏仁核和额叶皮质中高度丰富。我们最近确定 STEP 调节 MAP 激酶成员 ERKI/2 的活性。 STEP 本身受多巴胺和谷氨酸信号传导调节。多巴胺刺激会导致关键调节残基磷酸化并使 STEP 失活。谷氨酸信号传导去磷酸化并激活 STEP。因此，STEP 充当调节 ERK1/2 活性并限制其激活下游底物的能力的开关。 我们建议 STEP 调节安非他明的作用。它通过控制 ERKI/2 的活性来实现这一点。与这一假设一致，大鼠的初步数据表明，安非他明治疗后 STEP 被磷酸化。磷酸化位点是与 ERK 结合所需的结构域中的关键调节残基。当 STEP 在该位点被磷酸化时，ERK 信号级联反应得以维持。我们将进行精神兴奋剂的时程和剂量反应分析，并进行免疫细胞化学和蛋白质印迹分析，以确定 p-ERK、p-STEP、p-CREB、p-Elk-1 和立即早期基因 c-fos、jun 和 AfosB 的模式。我们认为 ERKI/2 保持活跃的持续时间决定了基因表达的模式。功能研究将破坏 STEP 与 ERK 结合的能力或破坏 STEP 释放 ERK 的能力。 这将通过使用 TAT 肽技术进行测试，该技术引入蛋白质序列，阻止 STEP 与 ERK 结合，或者永远不会释放 ERK。我们展示了这种方法的初步可行性数据。一组互补的实验将研究我们预测对兴奋剂治疗过敏的 STEP 敲除小鼠。