Carson S
Immunology Division, National Institute for Medical Research, The Ridgeway, London, UK.
Nucleic Acids Res. 1991 Sep 25;19(18):5007-14. doi: 10.1093/nar/19.18.5007.
The mouse class II major histocompatibility complex (MHC) encodes a polymorphic, multigene family important in the immune response, and is expressed mainly on mature B cells, on certain types of dendritic cells and is also inducible by gamma-interferon on antigen presenting cells. To study the regulatory elements which control this expression pattern, we have examined the chromatin structure flanking the class II MHC region, in particular during B cell differentiation. Using a panel of well-characterised mouse cell lines specific for different stages of B cell development (pre-B, B, plasma cell) as well as non-B cell lines, we have mapped the DNase I hypersensitive (DHS) sites adjacent to the mouse MHC class II region. The results presented show, for the first time that there are specific hypersensitive sites flanking the class II MHC locus during pre B cell, B cell and plasma cell stages of B cell differentiation, irrespective of the status of class II MHC expression. These hypersensitive sites are not found in T cell, fibroblast or uninduced myelomonocytic cell lines. This suggests that these DHS sites define a developmentally stable, chromatin structure, which can be used as a marker of B cell lineage commitment and may indicate that a combination of these hypersensitive sites reflect regulatory proteins involved in the immediate expression of a particular class II MHC gene or possibly control of the entire locus.
小鼠II类主要组织相容性复合体（MHC）编码一个在免疫反应中起重要作用的多态性多基因家族，主要在成熟B细胞、某些类型的树突状细胞上表达，并且在抗原呈递细胞上也可被γ干扰素诱导表达。为了研究控制这种表达模式的调控元件，我们检查了II类MHC区域侧翼的染色质结构，特别是在B细胞分化过程中。我们使用了一组对B细胞发育不同阶段（前B细胞、B细胞、浆细胞）具有特异性的、特征明确的小鼠细胞系以及非B细胞系，绘制了与小鼠MHC II类区域相邻的DNase I超敏（DHS）位点图谱。所呈现的结果首次表明，在B细胞分化的前B细胞、B细胞和浆细胞阶段，无论II类MHC的表达状态如何，II类MHC基因座侧翼都存在特定的超敏位点。这些超敏位点在T细胞、成纤维细胞或未诱导的骨髓单核细胞系中未发现。这表明这些DHS位点定义了一种发育稳定的染色质结构，可作为B细胞谱系定向的标志物，并且可能表明这些超敏位点的组合反映了参与特定II类MHC基因即时表达或可能控制整个基因座的调控蛋白。
