Sakamoto S, Young H A
Laboratory of Molecular Immunoregulation, National Cancer Institute, Frederick, MD 21701-1013.
Nucleic Acids Res. 1988 Mar 25;16(5):2149-63. doi: 10.1093/nar/16.5.2149.
In order to determine the relationship between the generation of a 1.0 kb mRNA and methylation of the T cell receptor beta chain gene, we have analyzed the methylation state of the T cell receptor beta chain gene (T beta) in monocyte and B cell DNA, focusing on the J1 and J2 regions of this gene in human genomic DNA. We have observed that a portion of the J2 region of T beta rich with CpG sequences is nonmethylated in both monocyte and B cell DNA but that the J1 region is methylated in both cell DNAs. We suggest that the hypomethylation of the J2 region constitutes a condition in which a 1.0 kb truncated mRNA of the beta chain gene is expressed in B cells. We have also found that the CpG sequence 1.0 kb 3' to the last exon of the J2 was totally nonmethylated in B cell DNA but methylated in half of monocyte DNA. This difference in methylation between monocyte and B cell DNA may reflect the differential transcriptional activity in monocytes and B cells of a 1.0 kb mRNA of T beta.
为了确定1.0 kb mRNA的产生与T细胞受体β链基因甲基化之间的关系，我们分析了单核细胞和B细胞DNA中T细胞受体β链基因（Tβ）的甲基化状态，重点关注人类基因组DNA中该基因的J1和J2区域。我们观察到，富含CpG序列的Tβ基因J2区域的一部分在单核细胞和B细胞DNA中均未甲基化，但J1区域在两种细胞DNA中均被甲基化。我们认为，J2区域的低甲基化构成了β链基因1.0 kb截短mRNA在B细胞中表达的条件。我们还发现，J2最后一个外显子3'端1.0 kb处的CpG序列在B细胞DNA中完全未甲基化，但在一半的单核细胞DNA中被甲基化。单核细胞和B细胞DNA之间这种甲基化差异可能反映了Tβ 1.0 kb mRNA在单核细胞和B细胞中的转录活性差异。
