TNF alpha Signaling: Effects on AMPA Receptor Location

TNF α 信号转导：对 AMPA 受体位置的影响

• 批准号: 6723284
• 负责人: ERIC C BEATTIE
• 金额: $ 29.24万
• 依托单位: CALIFORNIA PACIFIC MED CTR RES INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-20 至 2007-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6723284
• 关键词: AMPA receptors; brain mapping; calmodulin dependent protein kinase; cerebral cortex; cytokine receptors; electrophysiology; hippocampus; immunocytochemistry; laboratory mouse; laboratory rat; motor neurons; neural transmission; neurotoxicology; protein isoforms; protein localization; spinal cord; tissue /cell culture; tumor necrosis factor alpha

DESCRIPTION (provided by applicant): This proposal will study the tumor necrosis factor alpha (TNF-alpha) signaling cascade and its rapid effects on synaptic activity. TNF-alpha has been shown to increase synaptic activity in non-diseased neurons, and can induce excitotoxicity in neurons during disease or trauma. NMDA-type and AMPA-type glutamate receptors (NMDARs and AMPARs) expressed in excitatory neurons are known to have major roles in modulating synaptic activity. These receptors therefore are possible targets of TNF-alpha signaling regulation. In particular, AMPARs have been found to be a highly regulated and mobile component of the postsynaptic density and are thought to increase synaptic potentiation via rapid localization to NMDAR-containing synapses. Recently we have shown that TNF-alpha supplied to rat hippocampal neurons in culture rapidly (15 minutes) increased synaptic activity and AMPAR localization to synapses, but did not alter the localization of NMDARs. The signaling mechanisms underlying this are unknown. This proposal will examine TNF-alpha signaling pathways potentially responsible for the TNF-alpha-induced increase in AMPAR localization and synaptic activity. Subcellular AMPAR localization will be examined after various treatments in cultured neurons from two CNS regions, the hippocampus and spinal cord. The analysis will utilize cell biological, immunohistochemical, biochemical and electrophysiological techniques. The first three aims in this proposal will examine TNF-alpha signaling in cultured rat and mouse hippocampal neurons. Specific aim 1 will determine if signaling from one of the two TNF-alpha receptors- TNFR1, TNFR2, or both contribute to increased AMPAR surface localization. TNFR1 and TNFR2 are both expressed in hippocampal neurons and elicit overlapping yet distinct signaling pathways. Specific aim 2 will test the hypothesis that CamKII and a calcium mediated pathway are responsible for this activity. Aim 3 will investigate the intracellular origin of the AMPARs that appear on the neuron surface after TNF-alpha signaling. Finally, Aim 4 will ask if TNF-alpha is able to cause increases in surface AMPAR localization on neurons of different regions of the CNS, the cortex and spinal cord. If so, the details of TNF-alpha's signaling on AMPAR localization in motorneurons and cortical neurons will be assessed as hippocampal neurons were assessed in aims 1 through 3. These aims outline the logical next step extending our preliminary data showing that TNF-alpha increases synaptic AMPAR localization. The results will significantly increase our understanding of synaptic function in the CNS in both health and disease. CNS neurons that undergo excitotoxic cell death are oversupplied with TNF-alpha after stroke or spinal cord injury as well as during diseases such as Alzheimer's, Parkinson's, and ALS. Recent data linking TNF-alpha signaling to increased synaptic activity suggests that an oversupply TNF-alpha may kill neurons by moving excessive numbers of AMPARs to synapses. Thus, specific knowledge of how TNF-alpha signaling increases AMPAR surface localization in particular classes of CNS neurons may allow us to more effectively prevent excitotoxicity in a range of diseases and trauma.

描述（由申请人提供）：该提案将研究肿瘤坏死因子α（TNF-α）信号级联及其对突触活动的快速影响。 TNF-α 已被证明可以增加未患病神经元的突触活性，并且可以在疾病或创伤期间诱导神经元的兴奋性毒性。已知在兴奋性神经元中表达的 NMDA 型和 AMPA 型谷氨酸受体（NMDAR 和 AMPAR）在调节突触活动中具有重要作用。因此，这些受体可能是 TNF-α 信号传导调节的目标。特别是，AMPAR 被发现是突触后密度的高度调节和可移动的组成部分，并且被认为可以通过快速定位到含有 NMDAR 的突触来增加突触增强。最近我们发现，向培养的大鼠海马神经元提供 TNF-α 后，可快速（15 分钟）增加突触活性和 AMPAR 定位到突触，但不会改变 NMDAR 的定位。其背后的信号机制尚不清楚。 该提案将检查可能导致 TNF-α 诱导的 AMPAR 定位和突触活性增加的 TNF-α 信号通路。在对来自两个中枢神经系统区域（海马和脊髓）的培养神经元进行各种处理后，将检查亚细胞 AMPAR 定位。该分析将利用细胞生物学、免疫组织化学、生物化学和电生理学技术。该提案的前三个目标将检查培养的大鼠和小鼠海马神经元中的 TNF-α 信号传导。具体目标 1 将确定来自两种 TNF-α 受体之一（TNFR1、TNFR2 或两者）的信号传导是否有助于增加 AMPAR 表面定位。 TNFR1 和 TNFR2 均在海马神经元中表达，并引发重叠但不同的信号通路。具体目标 2 将检验 CamKII 和钙介导途径负责此活动的假设。目标 3 将研究 TNF-α 信号传导后出现在神经元表面的 AMPAR 的细胞内起源。最后，目标 4 将询问 TNF-α 是否能够导致中枢神经系统、皮质和脊髓不同区域的神经元表面 AMPAR 定位增加。如果是这样，则将像目标 1 至 3 中评估海马神经元一样评估运动神经元和皮质神经元中 AMPAR 定位的 TNF-α 信号传导细节。 这些目标概述了逻辑上的下一步，扩展了我们的初步数据，表明 TNF-α 增加了突触 AMPAR 定位。 这些结果将显着增加我们对健康和疾病中中枢神经系统突触功能的理解。中风或脊髓损伤后以及阿尔茨海默病、帕金森病和 ALS 等疾病期间，中枢神经系统神经元会出现兴奋性毒性细胞死亡，其中 TNF-α 供应过多。最近将 TNF-α 信号传导与突触活动增加联系起来的数据表明，过量的 TNF-α 可能会通过将过量的 AMPAR 转移到突触来杀死神经元。因此，关于 TNF-α 信号传导如何增加特定类别 CNS 神经元中 AMPAR 表面定位的具体知识可能使我们能够更有效地预防一系列疾病和创伤中的兴奋性毒性。