Mapping of DNase I-hypersensitive sites in the upstream DNA of human embryonic epsilon-globin gene in K562 leukemia cells.
We have mapped the DNase I-hypersensitive sites around the epsilon-globin and c-myc genes in two human leukemia cell lines K562 and HL60. In K562 cells in which the epsilon-globin gene is transcribed, six DNase I-hypersensitive sites are found in 6 kilobases (kb) of upstream flanking DNA; in HL60 cells in which the c-myc gene is expressed, two DNase I-hypersensitive sites are observed in 2 kb of upstream DNA. Neither the inactive epsilon-globin gene in HL60 cells nor the inactive c-myc gene in K562 cells displays such upstream DNase I-hypersensitive sites. Our results are consistent with previous studies that have shown DNase I-hypersensitive sites within 1 kb of the 5' end of other expressed genes. In addition, we have found sites displaying even more DNase I sensitivity further upstream of expressed epsilon-globin and c-myc genes. Among the six DNase I-hypersensitive sites of the expressed epsilon-globin gene in K562 cells, the most sensitive site is located about 6 kb upstream of the epsilon-globin gene. When correlated with the DNA sequence upstream of the epsilon-globin gene, this site was found to correspond to a region that contains a stretch of 28 consecutive Ts, three enhancer core-like sequences, and a stretch of consecutive (C-A)15(T-A)6 alternating purine and pyrimidine bases. These findings suggest the possibility that an enhancer element for epsilon-globin gene expression resides within this DNase I-hypersensitive site.
D000818:Animals; D001483:Base Sequence; D002843:Chromatin / Q000648:ultrastructure; D002874:Chromosome Mapping; D003850:Deoxyribonuclease I; D004706:Endodeoxyribonucleases; D005786:Gene Expression Regulation; D005914:Globins / Q000235:genetics*; D006801:Humans; D007942:Leukemia, Experimental / Q000235:genetics
D002843:Chromatin; D005914:Globins; D004706:Endodeoxyribonucleases; D003850:Deoxyribonuclease I