Lambert M, van Eggermond M C, Kraakman M E, Schuurman R K, van den Elsen P J
Department of Immunohaematology and Bloodbank, University Hospital, Leiden, The Netherlands.
Res Immunol. 1990 Feb;141(2):129-40. doi: 10.1016/0923-2494(90)90132-i.
The involvement of DNA methylation in aberrant MHC class II gene expression in EBV-transformed B-cell lines from 2 patients (THF and DGN) with the MHC class II deficiency syndrome (bare lymphocyte syndrome) was investigated. Incubation of the cells in the presence of various concentrations of 5-azadeoxycytidine resulted in the induction of expression of HLA DR genes in the DGN cell line, whereas, in the THF cell line, no effect of 5-azadeoxycytidine treatment on the expression of the HLA DR genes could be detected. Subsequent Southern blot analysis using methylation-sensitive restriction enzymes (ApyI, EcoRII and HhaI) and 5-azadeoxcycytidine-treated and untreated genomic DNA, indicated that the lack of HLA DR-A expression in the DGN cell line is not caused by hypermethylation of the 5' region of the HLA DR-A gene. These results indicate that 5-azadeoxycytidine treatment of the DGN cell line leads to activation of a methylation-sensitive factor that is involved in the regulation of transcription of the DR-A gene. In cell line THF, however, demethylation does not restore the activity of this factor. The lack of MHC class II expression in this cell line is caused by some other defect. The results of our analysis indicate that at least two different factors are involved in regulation of MHC class II gene expression.
研究了DNA甲基化在两名患有MHC II类缺陷综合征（裸淋巴细胞综合征）的患者（THF和DGN）的EB病毒转化B细胞系中异常MHC II类基因表达中的作用。在不同浓度的5-氮杂脱氧胞苷存在下培养细胞，结果在DGN细胞系中诱导了HLA DR基因的表达，而在THF细胞系中，未检测到5-氮杂脱氧胞苷处理对HLA DR基因表达的影响。随后使用甲基化敏感限制酶（ApyI、EcoRII和HhaI）以及经5-氮杂脱氧胞苷处理和未处理的基因组DNA进行Southern印迹分析，结果表明DGN细胞系中HLA DR-A表达的缺失并非由HLA DR-A基因5'区域的高甲基化所致。这些结果表明，对DGN细胞系进行5-氮杂脱氧胞苷处理可导致一种甲基化敏感因子的激活，该因子参与DR-A基因转录的调控。然而，在细胞系THF中，去甲基化并未恢复该因子的活性。该细胞系中MHC II类表达的缺失是由其他一些缺陷引起的。我们的分析结果表明，至少有两种不同的因子参与MHC II类基因表达的调控。
