Whole-genome methylation scan in ICF syndrome:: hypomethylation of non-satellite DNA repeats D4Z4 and NBL2
Whole-genome methylation scan in ICF syndrome:: hypomethylation of non-satellite DNA repeats D4Z4 and NBL2
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DOI：
10.1093/hmg/9.4.597
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发表时间：
2000-03-01
影响因子：
3.5
通讯作者：
Hanash, SM
中科院分区：
文献类型：
--
作者：
Kondo, T;Bobek, MP;Hanash, SM
知情同意书（免疫缺陷、着丝粒不稳定和面部畸形）综合征是一种罕见的隐性遗传疾病，其特征是免疫缺陷、某些异染色质区域的异常不稳定和编码DNA甲基转移酶3B的基因突变。（非着丝粒）异染色质，在有丝分裂原处理的ICF淋巴细胞和B细胞系中高度不稳定的相同区域，我们研究了4例ICF患者及其健康父母的B细胞系的CpG岛甲基化异常。在患者和对照组中，大多数限制性片段是相同的，表明ICF中的甲基化异常仅限于基因组的一小部分。然而，ICF DNA片段显著显示对照中不存在的多拷贝片段。我们克隆和测序了几个受影响的DNA片段，发现非卫星重复序列D4 Z4和NBL 2在所有四名患者中均强烈低甲基化，与其未受影响的父母相比。我们在正常细胞中观察到的D4 Z4的高度甲基化可能与该DNA重复序列在面肩肱型肌营养不良症中的位置效应杂色中的假定作用有关，并且也可能与ICF中的异常基因表达有关。我们在ICF样本中发现了一致的低甲基化和NBL 2重复序列的过度表达，这表明甲基化紊乱-该序列在ICF综合征中的调节表达。
The ICF (immunodeficiency, centromeric instability and facial abnormalities) syndrome is a rare recessive disease characterized by immunodeficiency, extraordinary instability of certain heterochromatin regions and mutations in the gene encoding DNA methyltransferase 3B, In this syndrome, chromosomes 1 and 16 are demethylated in their centromere-adjacent (juxtacentromeric) heterochromatin, the same regions that are highly unstable in mitogen-treated ICF lymphocytes and B cell lines, We investigated the methylation abnormalities in CpG islands of B cell lines from four ICF patients and their unaffected parents, Genomic DNA digested with a CpG methylation-sensitive restriction enzyme was subjected to two-dimensional gel electrophoresis. Most of the restriction fragments were identical in the digests from the patients and controls, indicating that the methylation abnormality in ICF is restricted to a small portion of the genome. However, ICF DNA digests prominently displayed multicopy fragments absent in controls. We cloned and sequenced several of the affected DNA fragments and found that the non-satellite repeats D4Z4 and NBL2 were strongly hypomethylated in all four patients, as compared with their unaffected parents. The high degree of methylation of D4Z4 that we observed in normal cells may be related to the postulated role of this DNA repeat in position effect variegation in facioscapulohumeral muscular dystrophy and might also pertain to abnormal gene expression in ICF, In addition, our finding of consistent hypomethylation and overexpression of NBL2 repeats in ICF samples suggests derangement of methylation-regulated expression of this sequence in the ICF syndrome.