Role of brain specific tyrosine phophatase, STEP in neuroprotection and death

项目摘要/摘要 这项研究的长期目标是确定酪氨酸磷酸酶的作用和双特异性 基底节及相关结构的神经性疾病中的磷酸酶。我们最近的发现表明 纹状体富含酪氨酸磷酸酶，STEP，在大脑皮层神经元中特异表达， 海马体和纹状体可能参与兴奋性损伤后的细胞存活。STEP的活动是 自身受神经递质多巴胺和谷氨酸通过磷酸化和 去磷酸化的关键丝氨酸残基的相互作用的基序或KIM结构域。 谷氨酸/NMDA受体介导的钙内流激活STEP，而多巴胺/D_1受体介导 PKA激活导致STEP失活。拟议的研究现在将测试STEP是否被激活 通过NR2B-NMDA受体，一个与谷氨酸兴奋性毒性相关的NMDA受体池。会的 还研究了主动步骤是否反过来可以下调或抑制多个相互关联的通路 参与谷氨酸/NMDA受体介导的细胞死亡。我们期待这一积极步骤，作为 反馈环，可通过酪氨酸去磷酸化下调NR2B-NMDA受体通道活性 NR2B亚基，从而抑制钙超载和随后的细胞损伤。它还能抑制细胞的激活。 多发性神经退行性变中与细胞死亡有关的p38MAP信号通路的研究 精神错乱。通过这种方式，STEP可能会在最初的侮辱后促进细胞存活。但是，取决于 侮辱步骤的严重性可以被蛋白水解性切割并最终被降解，从而促进 激活细胞死亡途径。这项研究将进一步调查是否有一种构成上活跃的步骤形式 不能被蛋白质分解并可以在体内传递将能够减轻缺血性脑损伤， 其中谷氨酸兴奋毒性的参与是很好的确定的。这些研究将涉及神经元培养。 谷氨酸毒性实验和缺血性中风的动物模型，并将利用生化， 免疫细胞化学和分子生物学技术。这些发现将帮助我们确定 酪氨酸磷酸酶步骤可能对治疗有益，可考虑用于治疗 缺血性中风和相关的神经疾病。项目叙事 这项拟议的研究的目标是了解一种富含大脑和神经元特异性的酪氨酸的作用。 磷酸酶，在兴奋性毒性伤害后神经细胞死亡中的一步。这些发现将帮助我们确定 STEP能否减轻兴奋性神经细胞死亡，可作为一种潜在的治疗方法 治疗缺血性中风和相关神经疾病的目标。

Project Summary / Abstract The long-term goal of this research is to determine the role of tyrosine phosphatases and dual-specificity phosphatases in neurological disorders of the basal ganglia and related structures. Our recent findings indicate that a striatal enriched tyrosine phosphatase, STEP, specifically expressed in the neurons of the cortex, hippocampus and striatum may participate in cell survival following an excitotoxic insult. The activity of STEP is itself regulated by the neurotransmitters dopamine and glutamate through phosphorylation and dephosphorylartion of a critical serine residue within the kinase interacting motif or KIM domain. Glutamate/NMDA receptor mediated influx of Ca2+ activates STEP, whereas dopamine/D1 receptor mediated PKA activation leads to inactivation of STEP. The proposed study will now test whether STEP is activated through NR2B-NMDA receptors, a pool of NMDA receptor that is associated with glutamate excitotoxicity. It will also investigate whether active STEP in turn can down regulate or inhibit multiple interrelated pathways that are involved in glutamate/NMDA receptor-mediated cell death. We anticipate that active STEP, as part of a feed-back loop, can down regulate NR2B-NMDA receptor channel activity through tyrosine dephosphorylation of NR2B subunit, thereby inhibiting Ca2+ overload and subsequent cell damage. It can also inhibit the activation of the p38 MAP kinase signaling pathway that has been attributed to cell death in multiple neurodegenerative disorders. In this way STEP may promote cell survival following an initial insult. However depending upon the severity of the insult STEP may be proteolytically cleaved and eventually degraded, thereby facilitating activation of cell death pathways. The study will further investigate if a constitutively active form of STEP that cannot be proteolytically cleaved and can be delivered in vivo will be able to attenuate ischemic brain damage, where the involvement of glutamate excitotoxicity is well established. These studies will involve neuron culture experiments of glutamate toxicity and an animal model of ischemic stroke and will utilize biochemical, immunocytochemical and molecular biology techniques. The findings will help us to determine whether the tyrosine phosphatase STEP may be therapeutically beneficial and can be considered for the treatment of ischemic stroke and related neurological disorders. Project Narrative The goal of the proposed study is to understand the role of a brain-enriched and neuron-specific tyrosine phosphatase, STEP, in neuronal cell death following an excitotoxic insult. The findings will help us to determine whether STEP can attenuate excitotoxic neuronal cell death and can be considered as a potential therapeutic target for the treatment of ischemic stroke and related neurological disorders.