Woolfrey A E, Andersen L C, Shewey L, Chung J, Nepom G T
Immunology & Diabetes Program, Virginia Mason Research Center, Seattle, Washington 98101.
J Leukoc Biol. 1993 Jun;53(6):697-706. doi: 10.1002/jlb.53.6.697.
Class II major histocompatibility complex genes are differentially expressed during cellular activation and differentiation, often in a locus-specific manner. We investigated the differential expression of the HLA-DQB gene, using B cell lines LAZ221 and LAZ388: LAZ221, derived from an early B cell leukemia, expresses HLA-DR but not HLA-DQ: LAZ388, the autologous Epstein-Barr virus-transformed B cell line, expresses both DR and DQ. Transfection experiments demonstrate differential function of class II gene upstream regulatory regions in the two lines, which correlates with differential class II gene expression. Using gel retardation and DNase I footprint assays, we demonstrate that absence of DQB gene expression is associated with characteristic nuclear protein-binding interactions in the proximal DQB gene upstream regulatory region. These interactions are visualized as DNA-protein complexes that are seen with nuclear proteins from the DQ-negative cell line, LAZ221, and involve consensus promoter Y box and W box elements, as well as novel upstream sites. Transcriptional regulatory proteins that differ in these autologous B cell lines may be stage-specific factors involved in the developmental regulation of HLA genes.
II类主要组织相容性复合体基因在细胞活化和分化过程中存在差异表达，且常常以位点特异性的方式进行。我们利用B细胞系LAZ221和LAZ388研究了HLA - DQB基因的差异表达：LAZ221源自早期B细胞白血病，表达HLA - DR但不表达HLA - DQ；LAZ388是自体EB病毒转化的B细胞系，同时表达DR和DQ。转染实验证明了II类基因上游调控区在这两个细胞系中的功能差异，这与II类基因的差异表达相关。通过凝胶阻滞和DNase I足迹分析，我们证明DQB基因表达的缺失与近端DQB基因上游调控区中特征性的核蛋白结合相互作用有关。这些相互作用表现为与DQ阴性细胞系LAZ221的核蛋白形成的DNA - 蛋白质复合物，涉及共有启动子Y盒和W盒元件以及新的上游位点。在这些自体B细胞系中存在差异的转录调节蛋白可能是参与HLA基因发育调控的阶段特异性因子。
