Silencing of CDKN1C (p57KIP2) is associated with hypomethylation at KvDMR1 in Beckwith-Wiedemann syndrome
Silencing of CDKN1C (p57KIP2) is associated with hypomethylation at KvDMR1 in Beckwith-Wiedemann syndrome
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DOI：
10.1136/jmg.40.11.797
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发表时间：
2003-11-01
影响因子：
4
通讯作者：
Higgins, MJ
中科院分区：
文献类型：
--
作者：
Diaz-Meyer, N;Day, CD;Higgins, MJ
背景：Beckwith-Wiedemann综合征(BWS)是由多种遗传和表观遗传学机制引起的，这些机制影响11p15.5号染色体印记基因的表达平衡。与BWS相关的最常见的改变是KvDMR1的母体等位基因缺乏甲基化，KvDMR1是KCNQ1基因内含子CpG岛。KvDMR1基因的靶向缺失提示该基因是11p15.5中调控多个基因的印记控制区。目的：探讨KvDMR1基因甲基化缺失(LOM)在BWS发生发展中的作用。方法：采用实时定量聚合酶链式反应(QPCR)和核糖核酸酶保护试验(RPA)检测KvDMR1基因甲基化缺失(LOM)在BWS患者和正常人成纤维细胞中的稳态表达水平。用甲基化敏感的限制性内切酶进行Southern杂交。结果：定量聚合酶链式反应和RPA均显示CDKN1C基因在KvDMR1发生LOM的BWS患者细胞中的表达水平明显降低(86-93%)。Southern分析表明，这些患者中CDKN1C基因的下调与CDKN1C启动子的高甲基化无关。结论：KvDMR1基因突变，母体甲基化缺失，导致母体染色体上约180kb的CDKN1C异常沉默。类似于该基因的突变，这种沉默可能会导致BWS。
Context: Beckwith - Wiedemann syndrome ( BWS) arises by several genetic and epigenetic mechanisms affecting the balance of imprinted gene expression in chromosome 11p15.5. The most frequent alteration associated with BWS is the absence of methylation at the maternal allele of KvDMR1, an intronic CpG island within the KCNQ1 gene. Targeted deletion of KvDMR1 suggests that this locus is an imprinting control region ( ICR) that regulates multiple genes in 11p15.5. Cell culture based enhancer blocking assays indicate that KvDMR1 may function as a methylation modulated chromatin insulator and/ or silencer.Objective: To determine the potential consequence of loss of methylation ( LOM) at KvDMR1 in the development of BWS.Methods: The steady state levels of CDKN1C gene expression in fibroblast cells from normal individuals, and from persons with BWS who have LOM at KvDMR1, was determined by both real time quantitative polymerase chain reaction ( qPCR) and ribonuclease protection assay ( RPA). Methylation of the CDKN1C promoter region was assessed by Southern hybridisation using a methylation sensitive restriction endonuclease.Results: Both qPCR and RPA clearly demonstrated a marked decrease ( 86 - 93%) in the expression level of the CDKN1C gene in cells derived from patients with BWS, who had LOM at KvDMR1. Southern analysis indicated that downregulation of CDKN1C in these patients was not associated with hypermethylation at the presumptive CDKN1C promoter.Conclusions: An epimutation at KvDMR1, the absence of maternal methylation, causes the aberrant silencing of CDKN1C, some 180 kb away on the maternal chromosome. Similar to mutations at this locus, this silencing may give rise to BWS.