Darby M K, Herrera R E, Vosberg H P, Nordheim A
EMBO J. 1986 Sep;5(9):2257-65. doi: 10.1002/j.1460-2075.1986.tb04493.x.
We have analyzed 1 kb of cloned human c-fos sequence (-711 to +287) for calf thymus DNA topoisomerase II cleavage sites in vitro. Using the anti-tumor drug VP16 (demethylepipodophyllotoxin-beta-D-glucoside) with purified topoisomerase II, we identify twelve sites. Five sites are clustered around position -306 in a region that possesses enhancer-like properties. A second cluster of three sites is positioned 15 bp upstream of the TATA promoter element. With a HeLa nuclear extract as a source of topoisomerase II, a subset of cleavage sites is conserved within the two clusters. The cleavage sites in the enhancer-like element are conserved in the homologous region of the murine c-fos. These findings raise the possibility that topoisomerase II is involved in mediation of mitogen-induced c-fos expression.
我们已经在体外分析了1kb克隆的人c-fos序列（-711至+287）中的小牛胸腺DNA拓扑异构酶II切割位点。使用抗肿瘤药物VP16（去甲基表鬼臼毒素-β-D-葡萄糖苷）与纯化的拓扑异构酶II，我们鉴定出12个位点。5个位点聚集在具有增强子样特性的区域中的-306位置附近。第二组3个位点位于TATA启动子元件上游15bp处。以HeLa细胞核提取物作为拓扑异构酶II的来源，在这两个簇中保守了一部分切割位点。增强子样元件中的切割位点在鼠c-fos的同源区域中是保守的。这些发现增加了拓扑异构酶II参与有丝分裂原诱导的c-fos表达介导的可能性。
