Levine F, Pious D
Immunogenetics. 1985;22(5):427-40. doi: 10.1007/BF00418089.
We studied the role of cytosine methylation in the control of HLA class II gene expression in isogenic sets of cells whose members differ in their expression of HLA class II genes. These included: T5-1, 6.1.6, and P30, which are a class II expressing B-cell line, a class II nonexpressing mutant derived from T5-1, and an HLA-DR expressing partial revertant derived from 6.1.6, respectively; the class II expressing B-cell line, SB, and the class II non-expressing T-cell line, HSB, from the same individual. The use of sets of cells that differ in the way their class II genes are regulated allows us to study how that difference is reflected in the methylation state of their class II genes. At least five out of six class II genes in nonexpressing cells have a CpG site that is demethylated, when compared with the same class II gene in the respective expressing cells. The results presented in this paper indicate that most methylation changes in and around class II genes have a correlation with their state of expression. Some of these changes reflect rather than determine the state of expression. Other methylation changes appear to directly affect expression, whereas some methylation differences neither correlate with nor influence gene expression. Although 5-azacytidine does not affect class II expression in T5-1 or 6.1.6, it does induce expression in HSB. This indicates that the basis for nonexpression of class II genes is different in 6.1.6 and HSB.
我们研究了胞嘧啶甲基化在同基因细胞系中HLA II类基因表达调控中的作用，这些细胞系成员的HLA II类基因表达存在差异。其中包括：T5-1、6.1.6和P30，它们分别是一个表达II类分子的B细胞系、一个源自T5-1的不表达II类分子的突变体，以及一个源自6.1.6的表达HLA-DR的部分回复突变体；来自同一个体的表达II类分子的B细胞系SB和不表达II类分子的T细胞系HSB。使用II类基因调控方式不同的细胞系，使我们能够研究这种差异如何反映在其II类基因的甲基化状态中。与各自表达细胞中的相同II类基因相比，不表达细胞中六个II类基因中至少有五个具有去甲基化的CpG位点。本文给出的结果表明，II类基因及其周围的大多数甲基化变化与其表达状态相关。其中一些变化反映而非决定表达状态。其他甲基化变化似乎直接影响表达，而一些甲基化差异既不与基因表达相关也不影响基因表达。虽然5-氮杂胞苷不影响T5-1或6.1.6中的II类分子表达，但它确实能诱导HSB中的表达。这表明6.1.6和HSB中II类基因不表达的基础不同。
