Transcriptional regulation of oxidative death

氧化死亡的转录调控

• 批准号: 6741048
• 负责人: Rajiv R Ratan
• 金额: $ 21.75万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-15 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6741048
• 关键词: Huntington's disease; amidohydrolases; apoptosis; brain disorder chemotherapy; cAMP response element binding protein; cerebral cortex; clinical research; corpus striatum; enzyme inhibitors; gel mobility shift assay; gene expression; gene mutation; genetic regulation; genetic transcription; immunoprecipitation; laboratory rat; mithramycin; nerve /myelin protein; neuroprotectants; neuroregulation; oxidative stress; pathologic process; protein structure; tissue /cell culture; transfection /expression vector

Huntington's Disease (HD) is an autosomal dominant disorder resulting from selective loss of neurons in the striatum and cerebral cortex. Loss of neurons in HD results from pathological expansion of CAG repeats encoding glutamine. Though the precise mechanisms by which glutamine repeats lead to neuronal loss in HD are unclear, oxidative stress, apoptosis, and transcriptional dysregulation have all been implicated in disease pathogenesis. To understand better oxidative and transcriptional mechanisms that may lead to neuronal loss in HD, we have utilized an in vitro model of oxidative stress in primary cortical neurons. In preliminary studies we have shown that oxidative cell death can be fully abrogated by sequence-selective DNA binding drugs, including mithramycin A (MMA) and chromomcyin A3. These agents are members of the aureolic acid antitumor antibiotics that share a common chromophore, aglycon ring, but differ in the nature of the sugar moieties connected to either side of the aglycone ring. Both antibiotics inhibit transcription during macromoleclar biosynthesis by binding to the "GC" rich transcriptional response elements. To test whether aureolic antibiotics can protect neurons in an in vivo model ofneurodegeneration that may inolve oxidative stress, we examined the effect of MMA in the R6/2 transgenic model of HD. We found that MMA prolongs survival in these mice by nearly 30%, a magnitude superior to any other single neuroprotective agent. These preliminary data are consistent with the overall hypothesis to be tested in this proposal: MMA inhibits neuronal death due to oxidative stress and/or mutant Huntington protein in vitro and in vivo by inhibiting the binding of pro-apoptotic zinc finger transcription factors such as TIEG, and enhancing the DNA binding of pro-survival transcription factors such as CREB. We will examine this hypothesis by determining whether protective concentrations of MMA inhibit TIEG binding to its GC rich DNA binding sites and whether TIEG is critical for oxidative death in cortical neurons. In the second aim, we will determine how MMA affects CREB DNA binding and whether increases in CREB DNA binding contribute to MMA's salutary effects. In the last specific aim, we will compare the mechanism of neuroprotection of MMA to those ofhistone deacetylase inhibitors, another class of transcriptional regulators. These studies will provide critical, mechanistic data on neuroprotective modulators of transcription.

亨廷顿病 (HD) 是一种常染色体显性遗传疾病，由纹状体和大脑皮层神经元选择性丧失所致。 HD 中神​​经元的丢失是由于编码谷氨酰胺的 CAG 重复序列的病理性扩张所致。 尽管谷氨酰胺重复导致 HD 神经元丢失的确切机制尚不清楚，但氧化应激、细胞凋亡和转录失调都与疾病发病机制有关。为了更好地了解可能导致 HD 神经元丢失的氧化和转录机制，我们利用了原代皮质神经元氧化应激的体外模型。在初步研究中，我们已经表明，序列选择性 DNA 结合药物（包括光神霉素 A (MMA) 和染色素 A3）可以完全消除氧化性细胞死亡。这些药物是金黄色酸抗肿瘤抗生素的成员，它们具有共同的发色团、苷元环，但是 连接到糖苷配基环两侧的糖部分的性质不同。两种抗生素都通过与富含“GC”的转录反应元件结合来抑制大分子生物合成过程中的转录。为了测试金环抗生素是否可以保护可能参与氧化应激的神经退行性变体内模型中的神经元，我们检查了 MMA 在 HD 的 R6/2 转基因模型中的作用。我们发现 MMA 可将这些小鼠的存活时间延长近 30%，这一幅度优于任何其他单一神经保护剂。这些初步数据与本提案中要测试的总体假设一致：MMA 通过抑制促凋亡锌指转录因子（如 TIEG）的结合，在体外和体内抑制氧化应激和/或突变亨廷顿蛋白引起的神经元死亡，并增强促生存转录因子（如 CREB）的 DNA 结合。我们将通过确定 MMA 的保护浓度是否抑制 TIEG 来检验这一假设 结合其富含 GC 的 DNA 结合位点，以及 TIEG 是否对皮质神经元氧化死亡至关重要。在第二个目标中，我们将确定 MMA 如何影响 CREB ​​DNA 结合以及 CREB ​​DNA 结合的增加是否有助于 MMA 的有益作用。在最后一个具体目标中，我们将比较 MMA 与另一类转录调节剂组蛋白脱乙酰酶抑制剂的神经保护机制。这些研究将为转录的神经保护调节剂提供关键的机制数据。