DNA modifications in primary pulmonary hypertension

描述（由申请人提供）：原发性肺动脉高压（PPH）的病理生物学与大约300个基因的表达变化有关。了解PPH中驱动异常转录的分子事件对于改进诊断和设计新疗法至关重要，但其机制目前尚不清楚。一些新出现的证据线支持PPH转录调控的新概念。其中最主要的是发现PPH肺组织细胞中存在氧化性DNA损伤。最近对人类皮质神经元的研究表明，选择性易损启动子中氧化DNA损伤的年龄相关积累会损害参与神经元存活和可塑性的基因的转录。相反，在培养的大鼠肺血管细胞中进行的实验表明，PPH中发现的生长刺激引起的启动子序列中靶向核苷酸特异性碱基修饰有助于诱导VEGF表达。整合这些不同的证据线导致了PPH异常基因表达的新概念。我们认为启动子序列中氧化修饰的平衡密度和核苷酸特异性模式控制PPH中基因表达的增加和减少。两个目标将被解决：目标1将测试假设，即PPH肺组织中上调或下调的基因启动子在氧化启动子修饰的平衡密度中显示变化，这可以预测基因的转录状态；并且，Aim 2将验证以下假设：VEGF mRNA表达升高的PPH患者肺DNA中VEGF启动子的核苷酸特异性氧化碱基修饰模式与VEGF表达降低的慢性阻塞性肺疾病继发肺动脉高压患者肺DNA中的氧化碱基修饰模式不同。这些“翻译”研究意义重大且具有创新性，因为启动子中氧化“修饰”的位置和密度是基因表达的决定因素这一概念是全新的。如果这种调节机制的证据扩展到PPH，它将指向基于检测序列特异性氧化DNA修饰的新诊断策略，以及DNA损伤和修复途径作为干预的潜在目标。最后，如果DNA在获得性疾病（如PPH）中受到氧化威胁，这将指向未被认识的体细胞突变、年龄相关血管病变和其他疾病的机制，其中ROS靶向基因发挥关键作用。

DESCRIPTION (provided by applicant): The pathobiology of primary pulmonary hypertension (PPH) is associated with changes in expression of about 300 genes. Understanding the molecular events driving abnormal transcription in PPH is critical for improved diagnosis and design of new therapies, but the mechanism(s) is currently unknown. Several emerging lines of evidence support a new concept for transcriptional regulation in PPH. Chief among these is the finding that oxidative DNA damage is present in cells from PPH lung tissue. Recent studies in human cortical neurons show that age-related accumulation of oxidative DNA damage in selectively vulnerable promoters impairs transcription of genes involved in neuronal survival and plasticity. Conversely, experiments in cultured rat pulmonary vascular cells suggest that targeted nucleotide specific base modifications in promoter sequences, caused by growth stimuli found in PPH, facilitate induction of VEGF expression. Integrating these disparate lines of evidence leads to a new concept for the abnormal gene expression in PPH. We propose that the equilibrium density and nucleotide-specific patterns of oxidative modifications in promoter sequences govern increases and decreases in gene expression in PPH. Two aims will be addressed: Aim 1 will test the hypothesis that promoters of genes that are up- or down-regulated in PPH lung tissue display changes in the equilibrium density of oxidative promoter modifications that are predictive of the transcriptional state of the gene; and, Aim 2 will test the hypothesis that nucleotide-specific pattern of oxidative base modifications in the VEGF promoter in lung DNA from PPH patients with increased VEGF mRNA expression differs from that in lung DNA from patients with pulmonary arterial hypertension secondary to chronic obstructive lung disease wherein VEGF expression is decreased. These "translational" studies are significant and innovative because the concept that the position and density of oxidative "modifications" in promoters are determinants of gene expression is entirely new. If evidence for this regulatory mechanism extends to PPH, it will point to novel diagnostic strategies founded on detection of sequence-specific oxidative DNA modifications and to DNA damage and repair pathways as potential targets for intervention. Finally, if DNA is oxidatively threatened in an acquired disease like PPH, this will point to unappreciated mechanisms of somatic mutation, age-related vasculopathies and other disorders wherein genes targeted by ROS play a pivotal role.