Biamonti G, Perini G, Weighardt F, Riva S, Giacca M, Norio P, Zentilin L, Diviacco S, Dimitrova D, Falaschi A
Istituto di Genetica Biochimica ed Evoluzionistica del Consiglio Nazionale delle Ricerche, Pavia, Italy.
Chromosoma. 1992;102(1 Suppl):S24-31. doi: 10.1007/BF02451782.
A single-copy 13.7 kb human DNA region (L30E) located on Ch. 19 p13.3 contains an origin of DNA replication in myeloid HL-60 cells. The origin was localized, by means of quantitative PCR within approximately 3000 bp, in a highly transcribed region containing at least two closely spaced genes with the same polarity of transcription, one encoding lamin B2 and the other an unidentified protein. The origin region overlaps an undermethylated "CpG island" at the 5'-end of the second transcription unit. A binding site (CACGTG) for basic helix-loop-helix (bHLH) DNA binding proteins such as USF/MLTF or MYC-MAX was located by DNase I footprinting analysis in the promoter of the second gene. DMSO differentiation of HL-60 cells, that completely shuts off replication, also drastically reduces the transcription of L30E region. On the other hand such treatment does not modify the methylation pattern of the CpG island and does not abolish the DNase I protection of the bHLH binding site.
位于19号染色体p13.3的一个单拷贝13.7 kb人类DNA区域（L30E）在髓系HL-60细胞中包含一个DNA复制起点。通过定量PCR，该起点定位在大约3000 bp范围内，位于一个高度转录区域，该区域包含至少两个转录方向相同、紧密相邻的基因，一个编码核纤层蛋白B2，另一个编码一种未知蛋白。起点区域与第二个转录单元5'端的一个低甲基化“CpG岛”重叠。通过DNA酶I足迹分析，在第二个基因的启动子中定位到了一个碱性螺旋-环-螺旋（bHLH）DNA结合蛋白（如USF/MLTF或MYC-MAX）的结合位点（CACGTG）。HL-60细胞经二甲基亚砜（DMSO）诱导分化后，复制完全停止，L30E区域的转录也大幅减少。另一方面，这种处理不会改变CpG岛的甲基化模式，也不会消除DNA酶I对bHLH结合位点的保护。
