Expression dynamics and functional implications of DNA topoisomerase IIβ in the brain

Mammalian DNA topoisomerase IIbeta; is a type II DNA topoisomerase that catalyses topological transformations of genomic DNA by the transport of one DNA double helix through another. The IIβ enzyme is highly expressed in cells that have undergone the final cell division and committed to differentiate into neuronal cells. The IIβ enzyme in the differentiating neuronal cells is located in the nucleoplasm and is actively engaged in its catalytic reaction in vivo. When enzyme action is interfered with a specific inhibitor in vitro, transcriptional induction of a subset of genes fails to occur during neuronal differentiation. Detailed analyses of developing rat cerebellum and the cerebrum of mice with disrupted IIβ genes have revealed that DNA topoisomerase IIβ is necessary for the developmentally regulated expression of certain genes in cells committed to a neuronal fate after the final division. Herein, we review a dynamic aspect of DNA topoisomerase IIβ in the brain with special emphasis on developing cerebellar neurons.