Methylation Microarray Studies Highlight PDGFA Expression as a Factor in Biliary Atresia.
Methylation Microarray Studies Highlight PDGFA Expression as a Factor in Biliary Atresia.
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DOI：
10.1371/journal.pone.0151521
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Matthews RP
中科院分区：
文献类型：
--
作者：
Cofer ZC;Cui S;EauClaire SF;Kim C;Tobias JW;Hakonarson H;Loomes KM;Matthews RP
胆道闭锁(BA)是一种进行性纤维炎症性疾病，是儿童肝移植的主要适应症。尽管有证据表明BA与遗传、感染、环境和炎症有关，但BA的病因仍不清楚。我们最近报道，与疾病和非疾病对照组相比，BA患者的胆管细胞DNA甲基化水平降低，这支持了DNA低甲基化在BA发病机制中的潜在作用。在目前的研究中，我们使用甲基化微阵列技术检测了人类BA肝脏中特定基因的甲基化状态。我们发现在BA样本中，与疾病对照和非疾病对照相比，在特定的遗传位点上存在全局DNA低甲基化。已知在BA中上调的Hedgehog通路成员SHH和GLI2都是低甲基化的，证实了这种方法是一种研究工具。另一个靠近PDGFA基因座的区域是BA中最显著的低甲基化区域，这表明可能存在异常表达。验证分析证实，PDGFA在BA肝脏中的转录和蛋白表达增加。我们还发现，PDGF-A蛋白特异性地定位于人肝脏样本中的胆管细胞。向斑马鱼幼体注射PDGF-AA蛋白二聚体可引起胆道发育和功能缺陷。此外，Hedgehog途径的激活导致斑马鱼幼体中PDGF-A的表达增加，从而在PDGF和Hedgehog途径之间提供了一种以前未知的联系。我们的发现提示DNA低甲基化是介导BA相关基因过度表达的一个特异性因素，并确认PDGF是BA发病机制中的一个新的候选因素。
Biliary atresia (BA) is a progressive fibro-inflammatory disorder that is the leading indication for liver transplantation in children. Although there is evidence implicating genetic, infectious, environmental, and inflammatory causes, the etiology of BA remains unknown. We have recently reported that cholangiocytes from BA patients showed decreased DNA methylation relative to disease- and non-disease controls, supporting a potential role for DNA hypomethylation in BA etiopathogenesis. In the current study, we examined the methylation status of specific genes in human BA livers using methylation microarray technology. We found global DNA hypomethylation in BA samples as compared to disease- and non-disease controls at specific genetic loci. Hedgehog pathway members, SHH and GLI2, known to be upregulated in BA, were both hypomethylated, validating this approach as an investigative tool. Another region near the PDGFA locus was the most significantly hypomethylated in BA, suggesting potential aberrant expression. Validation assays confirmed increased transcriptional and protein expression of PDGFA in BA livers. We also show that PDGF-A protein is specifically localized to cholangiocytes in human liver samples. Injection of PDGF-AA protein dimer into zebrafish larvae caused biliary developmental and functional defects. In addition, activation of the Hedgehog pathway caused increased expression of PDGF-A in zebrafish larvae, providing a previously unrecognized link between PDGF and the Hedgehog pathway. Our findings implicate DNA hypomethylation as a specific factor in mediating overexpression of genes associated with BA and identify PDGF as a new candidate in BA pathogenesis.