Acid-sensing channels as novel target for brain ischemia

酸感应通道作为脑缺血的新靶点

• 批准号: 7039175
• 负责人: ZHIGANG XIONG
• 金额: $ 35万
• 依托单位: LEGACY EMANUEL HOSPITAL AND HEALTH CENTER
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7039175
• 关键词: acidosis; biological signal transduction; brain injury; calcium flux; cell line; cerebral ischemia /hypoxia; fluorescence microscopy; fluorescent dye /probe; genetically modified animals; laboratory mouse; laboratory rat; membrane channels; neuropathology; neuroprotectants; protein isoforms; protein structure function; voltage /patch clamp

DESCRIPTION (provided by applicant): Brain acidosis is a common feature in acute neurological diseases particularly in ischemia, and has been assumed to play an important role in the pathology of neuronal injury. However, the cellular and molecular mechanisms underlying acidosis-induced injury remain uncertain, multifactorial and vague. We have substantial preliminary data demonstrating that activation of newly described acid-sensing ion channels (ASICs), members of Degenerin/EnaC superfamily, and subsequent Ca2+ entry through these channels are largely responsible for acidosis-induced, glutamate receptor-independent neuronal injury. In cultured mouse cortical neurons, lowering pH activates amiloride-sensitive ASIC currents. In the majority of these neurons, ASICs are also permeable to Ca2+, and activation of these channels induces increases in the concentration of intracellular Ca2+([Ca2+]i). Activation of ASICs by brief incubation of neurons with acidic solutions induces time-dependent cell injury in the presence of the blockers for both voltage-gated Ca2+ channels and the glutamate receptors. This acid-induced injury is, however, inhibited by the blockers of ASICs, and by reducing the extracellular [Ca2+]. Acid treatment of COS-7 cells that lack functional ASICs does not induce significant cell injury. Similar to the primary cultured neurons, acid treatment induces injury in organotypic brain slices, and the injury of brain slices is inhibited by the blockers of ASICs. Preliminary in vivo studies also demonstrate that intraventricular injection of ASIC1 blocker reduced the infarction volume, and knockout of the ASIC1 gene protects the mouse brain from ischemic injury. Furthermore, our preliminary studies demonstrate that ischemic treatment and metabolic inhibition dramatically potentiate the ASIC currents. This potentiation of ASICs in turn increases acidosis-induced neuronal injury. Our overall objective is to investigate the pathological role of ASICs in the central nervous system and to test the hypothesis that activation of ASICs with subsequent Ca2+ entry is largely responsible for acidosis-mediated, glutamate-independent ischemic brain injury. Specific Aims Aim 1. Ca2+ -permeability of acid-sensing ion channels in CNS neurons Aim 2. Specific subunit configurations are responsible for acidosis-induced neuronal injury Aim 3. Potentiation of ASIC currents by hypoxia/ischemia Aim 4. Neuroprotective role of ASIC blockers or ASIC gene knockout in an in vivo model of brain ischemia and the organotypic brain slices

描述（由申请人提供）：脑酸中毒是急性神经系统疾病的常见特征，尤其是在缺血中，并被认为在神经元损伤的病理学中起着重要作用。然而，酸中毒诱导的损伤的细胞和分子机制仍然不确定，多因素和模糊。我们有大量的初步数据，表明新描述的酸性离子通道（ASIC），degenerin/enac超家族成员的激活以及随后通过这些通道的CA2+进入，这在很大程度上是酸中毒诱导的，谷氨酸受体独立的神经元损伤。在培养的小鼠皮质神经元中，降低pH会激活艾米洛里德敏感的ASIC电流。在大多数这些神经元中，ASIC也可以渗透到Ca2+，而这些通道的激活诱导细胞内Ca2+的浓度增加（[Ca2+] i）。通过短暂孵育神经元与酸性溶液的激活在电压门控Ca2+通道和谷氨酸受体的阻滞剂存在下诱导时间依赖性细胞损伤。但是，这种酸诱导的损伤受到ASIC的阻滞剂的抑制，并通过减少细胞外[Ca2+]。缺乏功能性ASIC的COS-7细胞的酸治疗不会诱导重大细胞损伤。与原发性培养的神经元相似，酸治疗会诱导器官脑切片的损伤，并且ASIC的阻滞剂抑制了脑切片的损伤。初步体内研究还表明，脑室室内注射ASIC1阻滞剂减少了梗塞体积，而ASIC1基因的敲除可以保护小鼠脑免受缺血性损伤。此外，我们的初步研究表明，缺血性治疗和代谢抑制极大地增强了ASIC电流。 ASIC的这种增强反过来增加了酸中毒引起的神经元损伤。我们的总体目的是研究ASIC在中枢神经系统中的病理作用，并检验以下假设：随后CA2+进入的ASIC的激活在很大程度上是酸中毒介导的，谷氨酸独立的缺血性脑损伤的原因。具体目标 AIM1。CA2+ - CNS神经元中酸性离子通道的渗透性 AIM 2。特定的亚基构型负责酸中毒引起的神经元损伤 目标3。缺氧/缺血对ASIC电流增强 目标4。在脑缺血的体内模型和器官型脑切片中，ASIC阻滞剂或ASIC基因敲除的神经保护作用