DNA methylation in biliary development and disease

胆道发育和疾病中的 DNA 甲基化

• 批准号: 8676783
• 负责人: Kathleen Mary Loomes
• 金额: $ 45.84万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-15 至 2016-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8676783
• 关键词: Affect; Anatomy; Animal Model; Azacitidine; Biliary; Biliary Atresia; Biochemical Markers; Biological Markers; Biopsy Specimen; Candidate Disease Gene; Cells; Chemicals; Child; Clinical; Cytokeratin; DNA; DNA Methylation; DNA Methylation Inhibition; Defect; Development; Diagnosis; Disease; Epigenetic Process; Etiology; Family; Gene Expression; Gene Silencing; Genes; Genetic; Goals; Healthcare; Hepatobiliary; Histology; Infant; Injection of therapeutic agent; Institution; Interferon Type II; Interferons; Larva; Lead; Liver; Liver diseases; Macaca mulatta; Mammals; Measures; Mediating; Mediator of activation protein; Methylation; Modeling; Modification; Molecular; Mus; Mutant Strains Mice; Obstructive Jaundice; Organ; Pathogenesis; Pathway interactions; Patients; Pediatric Hospitals; Philadelphia; Play; Process; Proteins; Regulation; Repression; Resources; Role; Rotavirus; Sampling; Serum; Testing; Tissues; Work; Zebrafish; bile duct; cytokine; derepression; experience; genetic analysis; genetic manipulation; infancy; inhibitor/antagonist; liver biopsy; liver transplantation; mouse model; novel; promoter; tool

DESCRIPTION (provided by applicant): Biliary atresia (BA) is the most common cause of obstructive jaundice in infants and is lethal if uncorrected. BA affects 1/10,000 infants and is the leading indication for liver transplantation in children. The etiology of this fibroinflammatory disorder remains elusive, but recent work has implicated the cytokine interferon-gamma (IFN3) as having a crucial role, although the mechanism of IFN3 activation is unclear. IFN3 levels are elevated in patients with BA, and targeted deletion of IFNg inhibits development of the rhesus rotavirus (RRV)-injected mouse model of BA. The exclusive occurrence of BA in the developing liver suggests that developmental pathways play an important role in the pathogenesis of BA. Epigenetic modifications, such as DNA methylation, function as stable gene silencing mechanisms that repress gene expression in differentiated cells. Inhibition of DNA methylation, resulting in derepression of gene expression, has been shown to have a profound effect on development, and also increases the expression of IFN3 pathway genes. We have evidence that broad chemical (azacytidine [azaC]) or genetic (dnmt1, ahcy) inhibition of DNA methylation leads to defects in hepatobiliary development associated with a significant increase in IFN3 pathway genes, and that patients with BA demonstrate bile duct cell-specific DNA hypomethylation. These findings led us to hypothesize that bile duct cell DNA hypomethylation plays a pathogenic role in BA. We believe this to be mediated through TGF2, which plays a key role in biliary development and is inhibited by IFN3 activation. The goals of this proposal are to further understand the mechanisms by which inhibition of DNA methylation leads to developmental biliary defects, and to determine the importance of DNA methylation in the pathogenesis of BA. Our mechanistic studies will utilize zebrafish, in which we have considerable experience examining hepatobiliary development. Zebrafish are a facile model organism for studying development, as they develop rapidly ex vivo and there are considerable tools available for genetic manipulation and analysis. We will also utilize mouse models and take advantage of the high volume of patients with infantile biliary disease at The Children's Hospital of Philadelphia. Using these resources, we propose to test the hypothesis that DNA hypomethylation leads to biliary defects in zebrafish and mouse models and in patients with BA, and that activation of IFN3 plays a critical role.

描述（由申请人提供）：胆道闭锁 (BA) 是婴儿梗阻性黄疸的最常见原因，如果不加以纠正，会致命。 BA 影响 1/10,000 的婴儿，是儿童肝移植的主要适应症。这种纤维炎症性疾病的病因仍然难以捉摸，但最近的研究表明细胞因子干扰素-γ (IFN3) 具有至关重要的作用，尽管 IFN3 激活的机制尚不清楚。 BA 患者的 IFN3 水平升高，并且靶向删除 IFNg 可抑制注射恒河猴轮状病毒 (RRV) 的 BA 小鼠模型的发育。 BA 只出现在发育中的肝脏中，这表明发育途径在 BA 的发病机制中发挥着重要作用。表观遗传修饰（例如 DNA 甲基化）作为稳定的基因沉默机制发挥作用，抑制分化细胞中的基因表达。 DNA 甲基化的抑制会导致基因表达的去抑制，已被证明对发育具有深远的影响，并且还会增加 IFN3 途径基因的表达。我们有证据表明，DNA 甲基化的广泛化学（氮胞苷 [azaC]）或遗传（dnmt1、ahcy）抑制会导致与 IFN3 通路基因显着增加相关的肝胆发育缺陷，并且 BA 患者表现出胆管细胞特异性 DNA 低甲基化。这些发现使我们推测胆管细胞 DNA 低甲基化在 BA 中发挥致病作用。我们认为这是通过 TGF2 介导的，TGF2 在胆道发育中发挥关键作用，并受到 IFN3 激活的抑制。 该提案的目的是进一步了解 DNA 甲基化抑制导致胆道发育缺陷的机制，并确定 DNA 甲基化在 BA 发病机制中的重要性。我们的机制研究将利用斑马鱼，我们在检查肝胆发育方面拥有丰富的经验。斑马鱼是研究发育的简便模型生物，因为它们离体发育迅速，并且有相当多的工具可用于遗传操作和分析。我们还将利用小鼠模型并利用费城儿童医院大量的婴儿胆道疾病患者。利用这些资源，我们建议检验以下假设：DNA 低甲基化会导致斑马鱼和小鼠模型以及 BA 患者的胆道缺陷，并且 IFN3 的激活起着关键作用。