Krajewski W A, Luchnik A N
Koltsov Institute of Developmental Biology, USSR Academy of Sciences, Moscow.
Mol Gen Genet. 1991 Dec;230(3):442-8. doi: 10.1007/BF00280301.
An autonomously replicating plasmid constructed from bovine papiloma virus (BPV) and pBR322 was stably maintained as a nuclear episome in a mouse cell culture. Addition to a cell culture of sodium butyrate (5 mM) induced an increase in plasmid DNA supercoiling of 3-5 turns, an increase in acetylation of cellular histones, and a decrease in plasmid transcription by 2- to 4-fold. After withdrawal of butyrate, DNA supercoiling began to fluctuate in a wave-like manner with an amplitude of up to 3 turns and a period of 3-4 h. These waves gradually faded by 24 h. The transcription of the plasmid and acetylation of cellular histones also oscillated with the same period. The wave-like alterations were not correlated with the cell cycle, for there was no resumption of DNA replication after butyrate withdrawal for at least 24 h. In vitro chemical acetylation of histones with acetyl adenylate also led to an increase in the superhelical density of plasmid DNA. The parallel changes in transcription, histone acetylation, and DNA supercoiling in vivo may indicate a functional innerconnection. Also, the observed in vivo variation in the level of DNA supercoiling directly indicates the possibility of its natural regulation in eukaryotic cells.
一种由牛乳头瘤病毒（BPV）和pBR322构建的自主复制质粒在小鼠细胞培养物中作为核附加体稳定维持。向细胞培养物中添加丁酸钠（5 mM）可使质粒DNA超螺旋增加3 - 5圈，细胞组蛋白乙酰化增加，质粒转录减少2至4倍。丁酸钠撤除后，DNA超螺旋开始以波状方式波动，幅度高达3圈，周期为3 - 4小时。这些波动在24小时内逐渐消失。质粒转录和细胞组蛋白乙酰化也以相同周期振荡。这种波状变化与细胞周期无关，因为丁酸钠撤除后至少24小时内DNA复制没有恢复。用乙酰腺苷酸对组蛋白进行体外化学乙酰化也导致质粒DNA超螺旋密度增加。体内转录、组蛋白乙酰化和DNA超螺旋的平行变化可能表明存在功能上的内在联系。此外，观察到的体内DNA超螺旋水平变化直接表明了其在真核细胞中自然调控的可能性。
