PHYSIOLOGICAL REGULATION OF EUKARYOTIC TOPOISOMERASE-II

Topoisomerase II is an essential enzyme in all organisms with several independent roles in DNA metabolism. In this article we review our kno wledge on the regulation of the expression and catalytic activity of t opoisomerase II in both lower and higher eukaryotes. Current data indi cate that the regulation of topoisomerase II gene expression is comple x, with positive and negative controls in evidence at the level of bot h promoter activity and mRNA stability. Similarly, the activity of the mature enzyme can be regulated by the action of several different pro tein kinases. Of particular interest is the cell cycle-dependent phosp horylation of topoisomerase II, including multiple, mitosis-specific m odifications, which are proposed to regulate the essential chromosome decatenation activity of the enzyme. 0167-4781/98/$ - see front matter (C) 1998 Elsevier Science B.V. All rights reserved.