The Role of MKPs in Oxidative Neuronal Cell Death

许多由缺血引起的神经元损伤不是立即的，而是延迟的，除了兴奋性毒性细胞死亡外，被认为是由于压倒性的氧化应激和随后的细胞凋亡。同样，其他使人衰弱的疾病，如帕金森病和阿尔茨海默病，也与慢性氧化应激和神经退化有关。本研究的目的是研究神经元氧化应激过程中发生的信号事件，并设想在这种情况下防止神经元死亡的方法。谷氨酸诱导的氧化毒性，在小鼠海马细胞系HT22和初级未成熟神经元皮质神经元中，都是氧化应激和神经元细胞死亡的一个被充分研究的模型。关于丝裂原活化蛋白激酶（MAPK）磷酸酶（MKPs）在神经元氧化应激中的作用知之甚少。我们计划在HT22和初级皮质神经元中研究谷氨酸诱导氧化应激时MKPs的表达和活性的变化。此外，MKP3及其催化失活性突变体MKP3 C293S将被转染到两种细胞系统中，以研究该磷酸酶消除谷氨酸诱导的氧化毒性的能力。进一步的实验涉及构建一个配体诱导的MKP3-雌激素受体配体结合域（MKP3- er LBD），将允许在时间上控制MKP3对他莫昔芬的反应活性。

Much of the neuronal damage resulting from ischemia is not immediate but delayed and is thought to be due, in addition to excitotoxic cell death, to overwhelming oxidative stress and subsequent apoptosis. Similarly, other debilitating diseases such as Parkinson's Disease and Alzheimer's Disease have been linked with chronic oxidative stress and neurodegeration. It is the purpose of this proposal to investigate the signaling events that occur during oxidative stress in neurons and to conceive of approaches that may prevent neuronal death in this context. Glutamate-induced oxidative toxicity, both in the mouse hippocampal cell line, HT22, and primary immature neuronal cortical neurons, is a well-studied model of oxidative stress and neuronal cell death. Little is known about the role of the mitogen-activated protein kinase (MAPK) phosphatases (MKPs) during oxidative stress in neurons. We plan to investigate changes of expression and activity of MKPs during glutamate-induced oxidative stress in both HT22 and primary cortical neurons. In addition, MKP3 and its catalytically inactive mutant, MKP3 C293S, will be transfected into both cell systems in order to investigate the ability of this phosphatase to abrogate glutamate-induced oxidative toxicity. Further experiments involving the construction of a ligand- inducible MKP3-estrogen receptor ligand-binding domain (MKP3-ER LBD) will allow the temporal control of MKP3 activity in response to tamoxifen.