Astrocytes and ischemic brain injury

星形胶质细胞和缺血性脑损伤

• 批准号: 8606898
• 负责人: Rona G Giffard
• 金额: $ 36.24万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-03-15 至 2017-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8606898
• 关键词: Address; Affect; Aftercare; Algorithms; Apoptosis; Apoptotic; Astrocytes; BCL2 gene; Behavioral; Biological Assay; Brain; Brain Ischemia; Cell Death; Cells; Cerebral Ischemia; Cessation of life; Coculture Techniques; Failure; Family; Family member; Fright; Functional disorder; Funding; Gene Expression; Gene Family; Gene Targeting; Glial Fibrillary Acidic Protein; Heart Arrest; Hippocampus (Brain); Impairment; In Vitro; Individual; Injury; Ischemia; Ischemic Brain Injury; Label; Life; Luciferases; Matrix Metalloproteinases; Messenger RNA; MicroRNAs; Mitochondria; Modeling; Mutate; Neurologic; Neurological outcome; Neurons; Nucleotides; Outcome; Oxidative Stress; Patients; Prosencephalon; Protein Family; Proteins; Publishing; Reactive Oxygen Species; Regulation; Reperfusion Therapy; Reporter; Research; Resuscitation; Role; Seeds; Signal Transduction; Small Interfering RNA; Stress; Survivors; Testing; Time; Translating; Untranslated Regions; Up-Regulation; Work; cell type; clinical application; cytochrome c; dentate gyrus; disability; genetic regulatory protein; improved; in vivo; member; mitochondrial membrane; neuronal survival; neuroprotection; novel; prevent; response; small hairpin RNA; stroke therapy

DESCRIPTION (provided by applicant): One of the most feared disabilities in survivors of cardiac arrest is neurological impairment. Even brief global cerebral ischemia causes delayed loss of CA1 hippocampal neurons while sparing nearby hippocampal dentate gyrus (DG) neurons. Lack of consideration of the role of astrocytes is thought to be a factor in the failure o many potential stroke therapies aimed only at neuronal survival (Nedergaard and Dirnagl, 2005). In the prior funding period we demonstrated selective dysfunction of hippocampal CA1 astrocytes at early reperfusion times, long before CA1 neuron death. We published the first demonstration that potent protection of CA1 neurons can be achieved by targeting protective proteins selectively to hippocampal astrocytes. Although delayed CA1 neuronal death after transient ischemia is apoptotic, the regulation of the critically important BCL2 family following cerebral ischemia is not well understood. BCL2 family proteins are central regulators of the life/death decision in cells (Adams et al, 2007), and via their regulation of mitochondrial membrane integrity and function control apoptosis signaling. MicroRNAs (miRNAs) are a novel, abundant class of ~22-nucleotide RNAs that control gene expression post- transcriptionally. Although hundreds of miRNAs have been cloned, little is known about their real targets and functions. Numerous miRNAs are expressed in a cell-specific manner and the miR-29 family has been suggested to be astrocyte related (Smirnova et al, 2005). In this proposal we will investigate the role of miR-29 in brain ischemia and neuroprotection, evaluate manipulation of miR-29 as a novel target for neuroprotection, and assess potential targets of miR-29 in the BCL2 family. Using computational miRNA target prediction algorithms we found that miR-29 could potentially target messenger RNAs of several BCL2 family members, both pro- and anti-apoptotic. Aims 1 and 2 focus on the role of miR-29 in ischemic brain injury. We will first investigate how altering miR-29 expression changes ischemia-induced cell death in vivo and in vitro. Aim 2 will determine changes in miR-29 family member levels in response to ischemia, including cell type and hippocampal region specific changes with forebrain ischemia. We will then address the mechanisms of the miR-29 effects on cells focusing on mitochondrial function and oxidative stress. The role of miR-29 in selective CA1 astrocyte dysfunction will be tested. In addition to focusing on the role of miR-29 in outcome from injury, we need to investigate downstream targets. In Aim 3 we focus on 5 likely miR-29 targets, all members of the BCL2 family, focusing especially on pro-apoptotic PUMA. These are likely candidates for effects of miR-29 on mitochondrial function and oxidative stress. Overall this proposal will test the hypothesis that specific microRNAs are a novel and effective target for protection from ischemic brain injury, as well as advancing our understanding of the contributions of astrocyte regulation and impairment to neurological outcome following cardiac arrest and resuscitation.

描述（由申请人提供）：心脏骤停幸存者最害怕的残疾之一是神经功能障碍。即使是短暂的全脑缺血也会导致海马CA 1区神经元的延迟性丢失，而海马齿状回（DG）神经元则不受影响。缺乏对星形胶质细胞作用的考虑被认为是许多仅针对神经元存活的潜在卒中治疗失败的因素（Nedergaard和Dirnagl，2005）。在之前的资助期间，我们证明了海马CA 1区星形胶质细胞在早期再灌注时间的选择性功能障碍，早在CA 1区神经元死亡之前。我们发表了第一个证明，有效的保护CA 1神经元可以实现通过靶向保护蛋白选择性海马星形胶质细胞。虽然短暂性缺血后迟发性CA 1神经元死亡是凋亡，但脑缺血后至关重要的BCL 2家族的调控尚不清楚。BCL 2家族蛋白是细胞中决定生命/死亡的中心调节物（亚当斯等人，2007），并且通过它们对线粒体膜完整性和功能的调节来控制细胞凋亡信号传导。微小RNA（microRNAs，miRNAs）是一类新的、丰富的约22个核苷酸的RNA，在转录后调控基因表达.尽管已经克隆了数百种miRNAs，但对其真实的靶点和功能知之甚少。许多miRNA以细胞特异性方式表达，并且已经提出miR-29家族与星形胶质细胞相关（Smirnova et al，2005）。在本研究中，我们将研究miR-29在脑缺血和神经保护中的作用，评估miR-29作为神经保护新靶点的操作，并评估miR-29在BCL 2家族中的潜在靶点。使用计算miRNA靶预测算法，我们发现miR-29可能靶向几个BCL 2家族成员的信使RNA，包括促凋亡和抗凋亡。目的1和2关注miR-29在缺血性脑损伤中的作用。我们将首先研究如何改变miR-29的表达改变缺血诱导的细胞死亡在体内和体外。目的2将确定miR-29家族成员水平响应于缺血的变化，包括前脑缺血的细胞类型和海马区域特异性变化。然后，我们将讨论miR-29对细胞作用的机制，重点关注线粒体功能和氧化应激。将测试miR-29在选择性CA 1星形胶质细胞功能障碍中的作用。除了关注miR-29在损伤结果中的作用外，我们还需要研究下游靶点。在目标3中，我们关注5个可能的miR-29靶点，它们都是BCL 2家族的成员，尤其关注促凋亡的miR-29。这些可能是miR-29对线粒体功能和氧化应激的影响的候选者。总的来说，这项提议将测试特定microRNA是保护缺血性脑损伤的新的有效靶点的假设，以及推进我们对星形胶质细胞调节和损伤对心脏骤停和复苏后神经结局的贡献的理解。