REGULATIN OF GLOBIN GENE EXPRESSION BY 5' DNA SEQUENCES

尽管许多人类遗传疾病被定义为 人类β-珠蛋白基因座中或附近的突变，调节 人类β-珠蛋白基因的基因表达并不好， 明白 为了研究这种调节，我们使用了一个突变的人类 红白血病细胞系K562。 这些细胞可以合成 胚胎和胎儿球蛋白，而不是成人β-球蛋白，虽然 它们含有结构正常的β-珠蛋白基因， 诱导在瞬时异核体中表达。 因此，分子 K562细胞中的缺陷最有可能是由于反式- K562细胞和正常红系细胞之间的作用因子， 由于阻遏物的持续合成， 活化剂分子，或两者。 如果有负面的监管 K562细胞中的因子，其DNA结合位点的缺失可能 允许表达。 另一方面，含有DNA的缺失 正作用因子的结合位点应被视为 如果该基因是活跃的，则表达减少。 为了理解人类基因表达的调节， 我们正在研究β-珠蛋白基因的5'端DNA序列。 我们 对这段DNA的缺失分析表明， β-珠蛋白基因5'调控区，两个阴性对照 区域（NCR）和一个阳性对照区域（PCR）。 只有PCR K562细胞中，这些缺失似乎是特异性的， 在中国仓鼠和小鼠红白血病细胞系中研究。 已检测到与NCR 1和NCR 2结合的特异性蛋白质 在未诱导和诱导的K562细胞的核提取物中， 已经鉴定了它们结合的序列。 有一个 与NCR 1和NCR 2结合的常见蛋白质。 还有 蛋白质结合到它们之间的区域和阳性 控制区域。 这些结合蛋白的重要性在于 在研究中

Although a number of human genetic diseases have been defined as mutations in or near the human beta-globin gene locus, regulation of gene expression of the human beta-globin gene is not well understood. To study this regulation, we are using a mutant human erythroleukemia cell line, K562. These cells can synthesize embryonic and fetal globins but not adult beta-globin, although they contain a structurally normal beta-globin gene which can be induced to express in transient heterokaryons. Thus, the molecular defect in K562 cells is most likely due to differences in trans- acting factors between K562 cells and normal erythroid cells such as continuous synthesis of a repressor, lack of synthesis of an activator molecule, or both. If there is a negative regulatory factor in K562 cells, deletion of its DNA binding site might then allow expression. On the other hand, deletion of DNA containing a binding site for a positive acting factor should be seen as decreased expression if the gene were active. In an attempt to understand regulation of expression of the human beta-globin gene we are studying its 5' DNA sequences. Our deletion analysis of this DNA suggest there are at least three regulatory regions 5' to the beta-globin gene, two negative control regions (NCR) and one positive control region (PCR). Only the PCR appeared to be specific for K562 cells when these deletions were studied in a Chinese hamster and a mouse erythroleukemia cell line. Specific proteins which bind to NCR1 and NCR2 have been detected in nuclear extracts of uninduced and induced K562 cells and the DNA sequences to which they bind have been identified. There is a common protein which binds to both NCR1 and NCR2. There is also protein binding to the region between them and to the positive control region. The significance of these binding proteins is under investigation.