Transcriptional Elongation Requires DNA Double Stand Break and Repair

Abstract

TRIM28 plays a key role in transcriptional regulation by controlling RNA polymerase II entry from promoter-proximal pausing into processive elongation. We have shown that transcriptional activation involves TRIM28 phosphorylation by members of the phosphatidylinositol 3-kinase-related kinases (PIKKs) such as DNA-PK and ATM at HSPA1B. Here, we show that DNA double strand break (DSB) and repair proteins such as Topoisomerase IIB, phosphorylated TRIM28 (S824), phosphorylated DNA-PK (T2609), Ku70, and gH2AX, were rapidly accumulated at activated paused genes in vivo. Transcriptional activation-induced DSB was indicated by enrichment of γH2AX and activated DNA repair enzymes through in vivo cell based and genome-wide analyses and visualized through in vitro biochemical analysis. Our data reveal a novel transcriptional activation mechanism involving rapid DSB and repair.