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（特别是缺血）的常见特征，并被认为在神经元损伤的病理学中起重要作用。然而，酸中毒引起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，激活新描述的酸敏感离子通道（ASIC），成员的变性蛋白/EnaC超家族，和随后的Ca 2+进入通过这些通道在很大程度上负责酸中毒诱导的，谷氨酸受体非依赖性神经元损伤。在培养的小鼠皮层神经元中，降低pH激活阿米洛利敏感的ASIC电流。在大多数这些神经元中，ASIC也可渗透Ca 2+，并且这些通道的激活诱导细胞内Ca 2+（[Ca 2 +]i）浓度的增加。在电压门控Ca 2+通道和谷氨酸受体阻断剂的存在下，通过用酸性溶液短暂孵育神经元来激活ASIC诱导时间依赖性细胞损伤。然而，这种酸诱导的损伤被ASICs的阻断剂抑制，并通过减少细胞外[Ca 2 +]。缺乏功能性ASIC的COS-7细胞的酸处理不诱导显著的细胞损伤。与原代培养的神经元相似，酸处理引起器官型脑片的损伤，并且脑片的损伤被ASIC的阻断剂抑制。初步的体内研究还表明，脑室内注射ASIC 1阻断剂减少了梗死体积，并且ASIC 1基因的敲除保护小鼠脑免受缺血性损伤。此外，我们的初步研究表明，缺血治疗和代谢抑制显着增强ASIC电流。ASIC的这种增强反过来又增加了酸中毒诱导的神经元损伤。我们的总体目标是研究ASICs在中枢神经系统中的病理作用，并检验ASICs的激活和随后的Ca 2+进入在很大程度上是酸中毒介导的、谷氨酸非依赖性缺血性脑损伤的原因这一假设。具体目标 目标1。中枢神经系统酸敏感离子通道的Ca ~（2+）通透性 目标二。酸中毒引起的神经元损伤与特定的亚基构型有关 目标3.缺氧/缺血增强ASIC电流 目标4。ASIC阻断剂或ASIC基因敲除在脑缺血模型和器官型脑片中的神经保护作用