Epigenetic control of apoptotic susceptibility

凋亡易感性的表观遗传控制

• 批准号: 7317327
• 负责人: ALEXEI D KONDRATYEV
• 金额: $ 16.95万
• 依托单位: GEORGETOWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7317327
• 关键词: Age; Apoptosis; Apoptotic; Binding Sites; Brain; Brain Ischemia; Caspase; Cell Death; Condition; Consensus; CpG Islands; DNA Methylation; Data; Development; Developmental Gene Expression Regulation; Down-Regulation; Epigenetic Process; Family; Gene Expression; Gene Expression Profiling; Gene Silencing; Genes; Genetic; Genetic Transcription; Goals; Histones; Human; Hypermethylation; Injury; Island; Link; Methylation; Modification; Molecular; Nerve Degeneration; Neurons; Nucleic Acid Regulatory Sequences; Perinatal; Physiological; Play; Predisposition; Process; Promoter Regions; Rattus; Regulation; Regulatory Element; Reporting; Repression; Research Personnel; Role; Structure; Therapeutic; Transcription Initiation; Transcription Initiation Site; Traumatic Brain Injury; Work; caspase-3; gene repression; guanylyl-(3' -5' )-guanosine; member; neuron apoptosis; neuron loss; neuroregulation; novel; programs; promoter; transcription factor

DESCRIPTION (provided by applicant): Neuronal apoptosis plays an essential role in brain development and contributes to neuronal loss under various neurodegenerative conditions. Genetic studies established molecular mechanisms responsible for initiation and progression of apoptosis. A critical role in this process was attributed to members of the caspase family. Caspase-3 appears to be a major effector in neuronal apoptosis. While being a common feature of developing CNS, apoptosis is atypical for mature mammalian brain under normal physiological conditions, and recent reports provide evidence that neuronal susceptibility to injury-induced apoptosis also markedly declines during brain maturation. Our data link the developmental decrease in apoptotic potential to transcriptional repression of the caspase-3 gene. With this background our objective was to identify essential basic mechanisms that underlie the silencing of this gene in mature brain. We have identified, cloned and sequenced the rat caspase-3 gene promoter, examined function of its regulatory elements, and identified the corresponding promoter of the human caspase-3 gene. Expression profiling of the essential transcription factors, which regulate caspase-3 transcription, did not reveal significant changes in their expression during brain maturation, suggesting that other mechanisms are involved in developmental regulation of caspase-3 expression. Promoter regions of rat and human caspase-3 genes have common dense CpG islands surrounding corresponding major transcription start sites. These regions include several consensus Sp1 binding sites essential for caspase-3 transcription. Inhibition of transcription initiation of genes with such promoter structures is generally associated with epigenetic regulation by hypermethylation of GpG islands, and a role for DNA methylation in developmental regulation of gene expression has been suggested by several recent studies. The goal of this proposal is to evaluate a role for DNA methylation of the caspase-3 promoter in regulation of neural susceptibility to caspase-dependent cell death. Our working hypothesis is that methylation of essential regulatory regions of this gene results in downregulation of its expression in neural cells, which subsequently leads to the repression of apoptotic potential during brain development. We propose two Specific Aims: (1) To evaluate an extent of DNA methylation of the caspase-3 gene promoter and associated histone modifications in rat brain and primary neuronal cultures as functions of developmental age; and (2) To examine the effect of DNA methylation on the caspase-3 gene expression and apoptotic potential in primary neuronal cultures. This study may result in identification of a novel endogenous neuroprotective mechanism that may have an important impact on improvement of existing therapeutic strategies to treat certain neurodegenerative conditions, such as perinatal ischemia and brain trauma, where the contribution of caspase-dependent apoptosis to neuronal loss is highly significant.

描述（由申请人提供）：神经元凋亡在大脑发育中发挥重要作用，并导致各种神经退行性疾病下的神经元损失。遗传学研究建立了负责细胞凋亡启动和进展的分子机制。半胱天冬酶家族成员在此过程中发挥着关键作用。 Caspase-3 似乎是神经元凋亡的主要效应器。虽然细胞凋亡是中枢神经系统发育的一个常见特征，但在正常生理条件下，细胞凋亡对于成熟哺乳动物的大脑来说是非典型的，最近的报告提供的证据表明，在大脑成熟过程中，神经元对损伤诱导的细胞凋亡的敏感性也显着下降。我们的数据将细胞凋亡潜力的发育降低与 caspase-3 基因的转录抑制联系起来。在此背景下，我们的目标是确定成熟大脑中该基因沉默的重要基本机制。我们对大鼠Caspase-3基因启动子进行了鉴定、克隆和测序，检查了其调控元件的功能，并鉴定了人Caspase-3基因的相应启动子。调节 caspase-3 转录的必需转录因子的表达谱并未显示其表达在大脑成熟过程中发生显着变化，这表明其他机制参与了 caspase-3 表达的发育调节。大鼠和人 caspase-3 基因的启动子区域在相应的主要转录起始位点周围具有共同的密集 CpG 岛。这些区域包括几个对 caspase-3 转录至关重要的共有 Sp1 结合位点。具有此类启动子结构的基因转录起始的抑制通常与 GpG 岛超甲基化的表观遗传调控有关，并且最近的几项研究已经表明 DNA 甲基化在基因表达的发育调控中的作用。该提案的目的是评估 caspase-3 启动子的 DNA 甲基化在调节神经对 caspase 依赖性细胞死亡的敏感性中的作用。我们的工作假设是，该基因的重要调节区域的甲基化导致其在神经细胞中的表达下调，从而导致大脑发育过程中细胞凋亡潜力的抑制。我们提出了两个具体目标：（1）评估大鼠脑和原代神经元培养物中 caspase-3 基因启动子的 DNA 甲基化程度以及相关组蛋白修饰作为发育年龄的函数； (2) 检测原代神经元培养物中 DNA 甲基化对 caspase-3 基因表达和凋亡潜力的影响。这项研究可能会发现一种新的内源性神经保护机制，该机制可能对改善现有治疗策略产生重要影响，以治疗某些神经退行性疾病，例如围产期缺血和脑外伤，其中半胱天冬酶依赖性细胞凋亡对神经元损失的贡献是非常重要。