DNA topoisomerase I inhibition by camptothecin induces escape of RNA polymerase II from promoter-proximal pause site, antisense transcription and histone acetylation at the human HIF-1alpha gene locus.

ABSTRACT: Top1 inhibition by camptothecin (CPT) perturbs RNA polymerase II (Pol II) density at promoters and along transcribed genes suggesting an involvement of Top1 in Pol II pausing. Here, we demonstrate that Top1 inhibition favors Pol II escape from a promoter-proximal pausing site of the human HIF-1alpha gene in living cells. Interestingly, alternative splicing at exon 11 was markedly altered in nascent HIF-1alpha mRNAs, and chromatin structure was also affected with enhanced histone acetylation and reduced nucleosome density in a manner dependent on cdk activity. Moreover, CPT increases transcription of a novel long RNA (5'aHIF1alpha), antisense to human HIF-1alpha mRNA, and a known antisense RNA at the 3'-end of the gene, while decreasing mRNA levels under normoxic and hypoxic conditions. The

SUBMITTER: Baranello L 

PROVIDER: S-EPMC2800211 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature