Interactions between the nuclear matrix proteins and the 5'-flanking cis-acting elements of the human ε-globin gene

An erythroid-specific nuclear matrix protein (termed ε-NMPk) in K562 cells, which can specifically bind to the positive stage-specific regulatory element (ε-PRE Ⅱ , - 446- - 419 bp) upstream of the human ε-globin gene, has been identified by using gel mobility shift assay. Meanwhile, Southwestern blotting assay showed that the nuclear matrix protein ε-NMPk in K562, cells may be composed of two polypeptides ( ～ 40 ku). In addition, it is observed in the gel mobility shift assay that the nuclear matrix proteins from K562, HEL and Raji cells can bind to the silencer DNA ( - 392- - 177 bp) in the 5'-flanking sequence of human ε-globin gene respectively. However, the shift band K detected in K562 cells is different from shift band H/R in HEL and Raji cells, suggesting that a common nuclear matrix protein may exist in HEL and Raji cells. Results show that the nuclear matrix protein may play an important role in the regulation of the human ε-globin gene expression.     

Interactions between the nuclear matrix proteins and the 5′-flankingcis-acting elements of the human ε-globin gene

An erythroid-specific nuclear matrix protein (termed ε-NMP_k) in K562 cells, which can specifically bind to the positive stage-specific regulatory element (ε-PRE II, - 446 - 419 bp) upstream of the human ε-globin gene, has been identified by using gel mobility shift assay. Meanwhile, Southwestern blotting assay showed that the nuclear matrix protein ε-NMP_k in K562, cells may be composed of two polypeptides (∼ 40 ku). In addition, it is observed in the gel mobility shift assay that the nuclear matrix proteins from K562, HEL and Raji cells can bind to the silencer DNA (- 392 - 177 bp) in the 5′-flanking sequence of human ε-globin gene respectively. However, the shift band K detected in K562 cells is different from shift band H/R in HEL and Raji cells, suggesting that a common nuclear matrix protein may exist in HEL and Raji cells. Results show that the nuclear matrix protein may play an important role in the regulation of the human ε-globin gene expression.     

3,7-二硝基-二苯基溴盐诱导K562细胞株的凋亡

采用苔盼蓝染色法、MTT比色法研究了环状溴代鎓盐cBr对人慢性粒细胞白血病细胞株K562增殖的影响;并用同位素示踪技术(3H-TdR)研究了cBr对K562细胞DNA的损伤作用;从形态学(荧光显微镜、电镜观察)和生化特性(流式细胞术、3H-TdR掺入法分析)研究了cBr抑制K562细胞增殖作用的机制.结果表明:在体外cBr显著抑制K562细胞增殖,并对DNA造成损伤,提示cBr的作用是通过诱导细胞凋亡而进行的,是一种新型的免疫增强剂.     

Cyclin/PCNA is the auxiliary protein of DNA polymerase-delta

Identification of the cellular proteins whose expression is regulated during the cell cycle in normal cells is essential for understanding the mechanisms involved in the control of cell proliferation. A nuclear protein called cyclin of relative molecular mass 36,000 (Mr 36K), whose synthesis correlates with the proliferative state of the cell, has been identified in several cell types of human, mouse, hamster and avian origin. The rate of cyclin synthesis is very low in quiescent cells and increases several fold after serum stimulation shortly before DNA synthesis. Immunofluorescence and autoradiography studies have shown that the nuclear staining patterns of cyclin during S phase have a sequential order of appearance and a clear correlation can be found between DNA synthesis and cyclin positive nuclei. The proliferating cell nuclear antigen (PCNA) and cyclin have many common properties and it has been shown that these two are identical. Recently a protein which is required by DNA polymerase-delta for its catalytic activity with templates having low primer/template ratios has been isolated from calf thymus. We report here that cyclin and the auxiliary protein of DNA polymerase-delta are identical.