Rest-Activated Program of Gene Expression in Ischemia

描述(申请人提供)：REST/NRSF是一种基因沉默转录因子，在胚胎发育过程中广泛表达，在神经元终末分化中发挥重要作用。在神经前体细胞和非神经细胞中，REST积极抑制大量对突触可塑性和突触重塑至关重要的神经特异性基因，包括编码突触小泡蛋白、结构蛋白、电压敏感离子通道和AMPAR亚单位GluR2的基因。随着神经元的分化，静息下调对神经表型的诱导和维持至关重要。在胚胎发育过程中，REST表达的干扰会导致细胞凋亡、异常分化和图案化，甚至致死。REST及其靶基因的失调与唐氏综合征、阿尔茨海默病和一些髓母细胞瘤的发病机制有关。全脑缺血是一种神经系统疾病，短暂的神经元损伤会导致选择性、延迟性的海马神经元死亡。侮辱和细胞死亡之间的实质性延迟与转录变化的作用是一致的。该实验室的最新发现表明，缺血损伤激活了注定要死亡的神经元中的休息，并在全球缺血诱导的神经元死亡中牵涉到休息。这项拟议的研究旨在研究REST启动的转录变化程序在缺血中的作用。AMPAR亚单位GluR2、脑源性神经营养因子(BDNF)和u阿片受体是已知的静息靶点，与全脑缺血相关的兴奋性死亡有关。一个焦点将是静息依赖的GluR2和p受体基因表达的沉默以及BDNF表达的上调。其基本假设是，全脑缺血触发了转录因子REST沉默基因的下调，从而启动了一系列基因转录变化，并且一个或多个REST靶基因在全脑缺血诱导的神经元死亡中起关键作用。具体目标是：1)检测缺血后CA1神经元中REST抑制物复合体的激活，并确定REST是否与神经元死亡有因果关系。2)研究REST改变缺血后神经元靶基因的机制，确定REST依赖的染色质重塑是否与神经元死亡有关；3)发现新的REST靶基因，并确定它们是否与神经元死亡有关。我们的发现与受损神经元转录失调的观察结果一致，表明静息沉默的中断在全脑缺血的发病机制中起着关键作用。这项拟议的研究将对干预全球缺血的新治疗策略的开发产生影响。全球缺血是一种恢复性创伤，每年影响20万美国人。这项研究对其他疾病的研究也有意义，包括癫痫、中风、创伤性脑损伤、脊髓损伤和阿尔茨海默病。

DESCRIPTION (provided by applicant): REST/NRSF is a gene silencing transcription factor that is widely expressed during embryogenesis and plays a strategic role in terminal neuronal differentiation. In neural progenitors and non-neural cells, REST actively represses a large array of neural-specific genes important to synaptic plasticity and synaptic remodeling including those encoding synaptic vesicle proteins, structural proteins, voltage-sensitive ion channels, and the AMPAR subunit GluR2. As neurons differentiate, REST downregulation is essential for induction and maintenance of the neural phenotype. Perturbation of REST expression during embryogenesis results in cellular apoptosis, aberrant differentiation and patterning, and lethality. Dysregulation of REST and its target genes is implicated in the pathogenesis of Down's syndrome, Alzheimer's disease and some medulloblastomas. Global ischemia is a neurological disorder in which a brief neuronal insult induces selective, delayed death of hippocampal CA1 neurons. The substantial delay between insult and cell death is consistent with a role for transcriptional changes. Recent findings from this laboratory show that ischemic insults activate REST in neurons destined to die and implicate REST in global ischemia-induced neuronal death. The proposed research aims to study the role of the REST-initiated program of transcriptional changes in ischemia. The AMPAR subunit GluR2, brain-derived neurotrophic factor (BDNF) and the u opioid receptor are known targets of REST and are implicated in the excitotoxic death associated with global ischemia. A focus will be REST-dependent silencing of GluR2 and p receptor gene expression and upregulation of BDNF expression. The underlying hypothesis is that global ischemia triggers de-repression of the gene silencing transcription factor REST, which initiates a program of gene transcriptional changes and that one or more REST target genes are critical players in global ischemia-induced neuronal death. Specific Aims are 1) Examine activation of the REST repressor complex in post-ischemic CA1 neurons and determine whether REST is causally related to neuronal death. 2) Examine mechanisms by which REST alters target genes in post-ischemic neurons and determine whether REST-dependent chromatin remodeling is causally related to neuronal death; and 3) Identify novel REST target genes and determine whether they are causally related to neuronal death. Our findings are consistent with observations of transcriptional dysregulation in injured neurons and suggest that disruption of REST silencing has a critical role in the pathogenesis of global ischemia. The proposed research will impact on the development of new treatment strategies for intervention in global ischemia, a dehabilitating trauma that affects 200,000 Americans each year. This study has implications for research on other disorders including epilepsy, stroke, traumatic brain injury, spinal cord injury and Alzheimer's disease.