Eklund E A, Kakar R
Lurleen B. Wallace Tumor Institute, Department of Hematology and Oncology, and the Comprehensive Cancer Center, University of Alabama, Birmingham School of Medicine, Birmingham, Alabama 35294, USA.
J Biol Chem. 1997 Apr 4;272(14):9344-55. doi: 10.1074/jbc.272.14.9344.
The CYBB gene encodes gp91(phox), the heavy chain of the phagocyte-specific NADPH oxidase. CYBB is transcriptionally inactive until the promyelocyte stage of myelopoiesis, and in mature phagocytes, expression of gp91(phox) is further increased by interferon-gamma (IFN-gamma) and other inflammatory mediators. The CYBB promoter region contains several lineage-specific cis-elements involved in the IFN-gamma response. We screened a leukocyte cDNA expression library for proteins able to bind to one of these cis-elements (-214 to -262 base pairs) and identified TF1(phox), a protein with sequence-specific binding to the CYBB promoter. Electrophoretic mobility shift assay with nuclear proteins from a variety of cell lines demonstrated binding of a protein to the CYBB promoter that was cross-immunoreactive with TF1(phox). DNA binding of this protein was increased by IFN-gamma treatment in the myeloid cell line PLB985, but not in the non-myeloid cell line HeLa. Overexpression of recombinant TF1(phox) in PLB985 cells increased endogenous gp91(phox) message abundance, but did not lead to cellular differentiation. Overexpression of TF1(phox) in myeloid leukemia cell lines increased reporter gene expression from artificial promoter constructs containing CYBB promoter sequence. These data suggested that TF1(phox) increased expression of gp91(phox).
CYBB基因编码吞噬细胞特异性NADPH氧化酶的重链gp91(phox)。在骨髓生成的早幼粒细胞阶段之前，CYBB转录无活性，在成熟吞噬细胞中，干扰素-γ（IFN-γ）和其他炎症介质可进一步增加gp91(phox)的表达。CYBB启动子区域包含几个参与IFN-γ反应的谱系特异性顺式元件。我们筛选了白细胞cDNA表达文库，寻找能够与其中一个顺式元件（-214至-262碱基对）结合的蛋白质，并鉴定出TF1(phox)，一种与CYBB启动子具有序列特异性结合的蛋白质。用来自多种细胞系的核蛋白进行的电泳迁移率变动分析表明，有一种蛋白质与CYBB启动子结合，该蛋白质与TF1(phox)具有交叉免疫反应性。在髓系细胞系PLB985中，IFN-γ处理可增加这种蛋白质的DNA结合，但在非髓系细胞系HeLa中则不然。在PLB985细胞中过表达重组TF1(phox)可增加内源性gp91(phox)信息丰度，但不会导致细胞分化。在髓系白血病细胞系中过表达TF1(phox)可增加含有CYBB启动子序列的人工启动子构建体的报告基因表达。这些数据表明TF1(phox)可增加gp91(phox)的表达。
