Role of Astrocytic TREK-2 Potassium Channels in Cerebral Ischemia

星形胶质细胞 TREK-2 钾通道在脑缺血中的作用

• 批准号: 8118568
• 负责人: MISTY J EATON
• 金额: $ 27.02万
• 依托单位: UNIVERSIDAD CENTRAL DEL CARIBE
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8118568
• 关键词: Acidosis; Anoxia; Arachidonic Acids; Astrocytes; Award; Biochemistry; Biological Assay; Biology; Blood flow; Brain; Brain Hypoxia-Ischemia; Budgets; Buffers; Cause of Death; Cell physiology; Cells; Cellular biology; Cerebral Ischemia; Cessation of life; Coculture Techniques; Collaborations; Data; Depressed mood; Development; Disease; Doctor of Philosophy; Educational workshop; Event; Faculty; Fostering; Funding; Genetic Transcription; Glutamates; Goals; Grant; Grant Review; Health; Homeostasis; Hour; Human Resources; Hypoglycemia; Hypoxia; Institutes; International Agencies; Intervention; Ischemia; Ischemic Stroke; Journals; Kansas; Laboratories; Lead; Letters; Mainstreaming; Maintenance; Manuscripts; Mechanics; Mediator of activation protein; Medical; Membrane; Membrane Potentials; Mentors; Minority; Molecular Biology; Neuroglia; Neurons; Neurosciences; New York; Paper; Pathway interactions; Peer Review; Phospholipase; Physiological; Play; Polyunsaturated Fatty Acids; Positioning Attribute; Postdoctoral Fellow; Potassium; Potassium Channel; Potassium Glutamate; Productivity; Proteins; Publications; Quinine; RNA Interference; Research; Research Institute; Research Personnel; Research Support; Role; Running; Science; Scientist; Severities; Signal Transduction; Simulate; Societies; Stretching; Stroke; Students; Study Section; Suggestion; Survivors; Swelling; Synapses; Synaptic Transmission; Tandem Pore Domain Potassium Channels; Techniques; Testing; Time; Training; Translations; Traumatic Brain Injury; Underrepresented Minority; United States; United States National Institutes of Health; Universities; Up-Regulation; Work; Writing; career; channel blockers; design; driving force; editorial; excitotoxicity; extracellular; gamma-Aminobutyric Acid; in vitro Model; interest; killings; knock-down; medical schools; medical specialties; meetings; member; methionylmethionine; neuron loss; neuronal excitability; neuroprotection; professor; public health relevance; research study; restoration; spreading depression; symposium; voltage clamp

DESCRIPTION (provided by applicant): Strokes are the third-leading cause of death in the United States killing about 275,000 people a year. One of the major mediators of neuronal death due to ischemic stroke is the elevated level of glutamate in the extracellular synaptic space which leads to excitotoxicity and neuronal cell death. Astrocytes, the most numerous cells in the brain, are essential for neuronal viability and stimulation of key astrocytic functions such as glutamate and potassium homeostasis in ischemic or post-ischemic brain could potentially contribute to neuroprotection. Potassium channels in astrocytes are predominantly responsible for maintaining the hyperpolarized membrane potential of astrocytes which allows these cells to effectively take up glutamate and K+. One type of K+ channel localized in astrocytes that is likely to be pertinent during ischemic conditions is the TREK-2 tandem-pore domain K+ channel. TREK-2 channels are activated by polyunsaturated fatty acids, intracellular acidosis in the physiological range and by mechanical stretch. During ischemia, activation of phospholipases promotes liberation and accumulation of arachidonic acid, the intracellular pH of astrocytes becomes acidic and astrocytes swell. All of these changes will activate TREK-2 channels in astrocytes to help maintain extracellular glutamate and K+ concentrations low during pathological events such as anoxia, ischemia, hypoxia, hypoglycemia and/or spreading depression. Our working hypothesis is that TREK-2 potassium channels play a major role in potassium buffering and glutamate clearance during ischemia and this hypothesis is supported by our preliminary data demonstrating functional upregulation of TREK-2 channels in astrocytes after experimental ischemia. Using a combination of techniques (such as RNAi, whole cell voltage clamp, glutamate clearance assays and an in vitro model of ischemia), we propose to directly examine the role of TREK-2 channels in maintaining the membrane potential of astrocytes and in buffering glutamate and K+ during normal and pathological conditions (glutamate excitoxicity, anoxia and hypoglycemia), as well as their ability to protect neurons during ischemic insults such as stroke. PUBLIC HEALTH RELEVANCE: Although strokes are the third-leading cause of death in the United States, there are about 5.4 million stroke survivors in the United States today. Despite the severity of the insult, many cells are not irreversibly damaged within the first few hours and can be rescued by early restoration of blood flow or other interventions. Astrocytes, the most numerous cells in the brain, normally perform many functions that are essential for neuronal viability and stimulation of astrocytic functions such as potassium buffering and glutamate clearance in ischemic or post-ischemic brain could potentially contribute to neuroprotection. The significance of the proposed experiments is that they represent a comprehensive effort to mechanistically elucidate the role of TREK-2 channels in astroctyes in the maintenance of neuronal function during pathophysiological conditions such as ischemia due to stroke.

描述（由申请人提供）：中风是美国第三大死因，每年约有 275,000 人死亡。缺血性中风引起的神经元死亡的主要介质之一是细胞外突触间隙中谷氨酸水平升高，这导致兴奋性毒性和神经元细胞死亡。星形胶质细胞是大脑中数量最多的细胞，对于神经元活力至关重要，刺激关键星形胶质细胞功能（例如缺血或缺血后大脑中的谷氨酸和钾稳态）可能有助于神经保护。星形胶质细胞中的钾通道主要负责维持星形胶质细胞的超极化膜电位，从而使这些细胞能够有效吸收谷氨酸和 K+。 TREK-2 串联孔结构域 K+ 通道是星形胶质细胞中可能与缺血条件相关的一种 K+ 通道。 TREK-2 通道由多不饱和脂肪酸、生理范围内的细胞内酸中毒和机械拉伸激活。缺血时，磷脂酶的激活促进花生四烯酸的释放和积累，星形胶质细胞的细胞内pH值呈酸性，星形胶质细胞肿胀。所有这些变化将激活星形胶质细胞中的 TREK-2 通道，以帮助在缺氧、缺血、缺氧、低血糖和/或扩散性抑郁等病理事件期间维持细胞外谷氨酸和 K+ 浓度较低。我们的工作假设是 TREK-2 钾通道在缺血期间的钾缓冲和谷氨酸清除中发挥主要作用，并且我们的初步数据证明了这一假设，该数据表明实验性缺血后星形胶质细胞中 TREK-2 通道的功能上调。结合使用多种技术（例如 RNAi、全细胞电压钳、谷氨酸清除测定和体外缺血模型），我们建议直接检查 TREK-2 通道在正常和病理条件（谷氨酸兴奋毒性、缺氧和低血糖）期间维持星形胶质细胞膜电位和缓冲谷氨酸和 K+ 中的作用，以及它们 在中风等缺血性损伤期间保护神经元。 公共卫生相关性：尽管中风是美国第三大死因，但目前美国约有 540 万中风幸存者。尽管损伤很严重，但许多细胞在最初的几个小时内并没有受到不可逆转的损害，可以通过早期恢复血流或其他干预措施来挽救。星形胶质细胞是大脑中数量最多的细胞，通常执行许多对神经元活力和刺激星形胶质细胞功能至关重要的功能，例如缺血或缺血后大脑中的钾缓冲和谷氨酸清除可能有助于神经保护。这些实验的意义在于，它们代表了一项全面的努力，旨在从机制上阐明星形细胞中 TREK-2 通道在中风缺血等病理生理条件下维持神经元功能的作用。