Ca A/K Channel Regulation in Hippocampal Neurons

描述（由申请人提供）：该项目的广泛，长期目标 目的是发现Ca 2+渗透性AMPA/红藻氨酸（Ca-A/K）通道在 海马神经元亚群的选择性神经变性 在缺血性、癫痫性或创伤性脑损伤后，如果这些通道 在一些神经退行性疾病如ALS和AD中也很重要。的 AMPA通道的Ca 2+渗透性由亚基的存在决定 GluR 2，其使得AMPA通道对Ca 2+不可渗透。以前的研究 证明了在一些情况下GluR 2 mRNA和肽的下调， 脑损伤的形式表明，在某些情况下， 通过形成新的Ca-A/K通道介导， Ca 2+或Zn 2+内流，离子稳态丧失，最终死亡。到目前为止， 然而，没有人直接证明了 损伤后GluR 2蛋白的损失。我们假设Ca-A/K的数量 通道在突触部位受到动态调节， 可能介导过量的离子流，在某些形式的神经变性中， Ca-A/K通道数量的上调确实发生， 下调GluR 2。我们首先建议开发一种细胞培养系统， 使用荧光成像评估Ca-A/K通道的存在和数量， 免疫细胞化学然后，我们将使用该系统来评估对 功能性突触Ca-A/K通道的处理后培养的神经元， 模拟损伤的条件，或分子生物学程序， 可能改变Ca-A/K通道水平。我们还建议测试我们的假设 在体内，使用红藻氨酸诱导的癫痫发作模型来评估突触GluR 2水平。

DESCRIPTION (provided by applicant): The broad, long-term goal of this project is to discover the role of Ca2+ permeable AMPA/Kainate (Ca-A/K) channels in selective neurodegeneration of a subpopulation of neurons in the hippocampus following ischemic, epileptic, or traumatic brain injury, and if these channels are also important in some neurodegenerative diseases such as ALS and AD. The Ca2+ permeability of AMPA channels is determined by the presence of the subunit GluR2, which renders AMPA channels impermeable to Ca2+. Previous studies demonstrating the down regulation of GluR2 mRNA and peptide following some forms of brain insult suggests that neuronal death in some cases may be mediated by the formation of new Ca-A/K channels that could lead to excessive Ca2+ or Zn2+ influx, loss of ionic homeostasis, and eventual death. To date, however, no one has demonstrated directly the physiological relevance of the loss of GluR2 protein following insult. We hypothesize that numbers of Ca-A/K channels are dynamically regulated at synaptic sites where they would most likely mediate excessive ion flux, and that in some forms of neurodegeneration, an upregulation in the number of Ca-A/K channels does indeed occur due to the down regulation of GluR2. We first propose to develop a cell culture system to assess presence and numbers of Ca-A/K channels using fluorescent imaging and immunocytochemistry. We will then use this system to assess regulation of functional synaptic Ca-A/K channels following treatment of cultured neurons to injury mimicking conditions, or molecular biological procedures that may potentially alter Ca-A/K channel levels. We also propose to test our hypothesis in vivo, using a kainate induced seizure model to asses synaptic GluR2 levels.