Regulation by PU.1 of CYBB Expression

吞噬细胞NADPH氧化酶产生对微生物杀灭至关重要的超氧阴离子，并在成熟的中性粒细胞表面表达。嗜酸性粒细胞、单核/巨噬细胞和B淋巴细胞。它是一个多组分的cnzyme，含有gp9lPhox，这是一种黄血红素蛋白，编码在X染色体上的CyBB中。因此，该基因的异常占被称为慢性肉芽肿性疾病的NADPH氧化酶缺陷的70%以上。我们最近发现了一例表型正常的慢性粒细胞增多症患者，并提出了中性粒细胞、单核细胞和B淋巴细胞特有的某些机制：启动子序列分析显示，在CyBB的-53位C到T点突变。迁移率改变分析显示，PU1和造血相关因子-L(HIF-1)是结合蛋白，其结合对这种突变敏感。我们发现-56G和-50G突变分别无法与HAF-1和PU.1结合。AS-53T突变使启动子活性下降，而不是前者。因此，这些结果表明PU.1，而不是HIF-1，对于中性粒细胞、单核细胞和B淋巴细胞中的CYBB的表达是必不可少的。PU1与转录调节剂的相互作用目前正在实验中。PU.1也可在嗜酸性粒细胞中检测到，并可能在细胞中对CYBB激活起重要作用，即使它不是必需的。此外，我们还发现GATA-3是嗜中性粒细胞特异性的细胞色素B抑制因子。

Phagocyte NADPH oxidase makes superoxide anion which is essential for microbial killing and is expressed on the surface of mature neutrophils. eosinophils, monocytes/macrophages and B lymphocytes. It is a multi-component cnzymes and contains gp9lphox, a flavo-heme protein, which is encoded in CYBB on X chromosome. Abnormalities of this gene, therefore, occupy more than 70% of NADPH oxidase deficiency called chronic granulomatous disease. We rcccntly discovered a CGD patient with phenotypically normal eosinophils, and suggested certain mechnisrn particular to neutrophils, monocytes and B lymphocytes : Analysis of promoter sequence revealed a C to T point mutation at -53 of CYBB Electrophoresis mobility shift assays exhibited PU.1 and hematopoietic associated factor-l(HAF-1) as the binding proteins whose binding is sensitive to this mutation. We discovered -56G and -50G mutations to fail in binding to only HAF-1 and PU.1, respectively. The latter mutation but not the former one decreased the promoter activity as -53T mutation. Accordingly these results indicate PU.l, but not HAF-1, to be essential for the expression of CYBB in neutrophils, monocytes, and B lymphocytes. Interaction of PU.1 with transcriptional modulators are now under experiments. PU.1 is also detectable in eosinophils, and may have a significant role in the cells for CYBB activation, even if it is not essential. In addition, we found GATA-3 to be ensinophil-specific repressor of CYBB.