Premium
DNA Breaks and Damage Response Signaling are Coupled with RNA Polymerase II Promoter‐Proximal Pause Release and Required for Effective Transcriptional Elongation
Author(s) -
Bunch Heeyoun
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.589.1
Subject(s) - rna polymerase ii , dna damage , microbiology and biotechnology , processivity , biology , dna , dna polymerase , transcription (linguistics) , gene , chemistry , promoter , gene expression , genetics , linguistics , philosophy
We have discovered a novel function of the factor tri partite m otif‐containing 28 (TRIM28) to stabilize RNA polymerase II (Pol II) promoter‐proximal pausing at many stimulus‐inducible protein‐coding genes in mammalian cells during the un‐induced state. Upon transcriptional activation that releases paused Pol II, TRIM28 is phosphorylated at residue S824, dependent on phosphoinositide‐3 kinases such as DNA‐PK and ATM. Importantly, we have recently identified that the involvement of these DNA repair enzymes indeed indicates a coupling of DNA breaks and DNA damage response (DDR) signaling with processive elongation of Pol II. This was evidenced by enrichment of γH2AX in the gene bodies of transcriptionally activated genes and by global DNA‐PK co‐localization with Ser2 phosphorylated Pol II at C‐terminal domain (S2 Pol II). DNA breaks induced by transcriptional activation were also visualized in the cellular level and at a representative paused gene, HSPA1B through comet assay and primer extension analysis, respectively. Strikingly, DNA breaks and DDR signaling not only coincide with activated transcription but also are required for effective Pol II pause release and subsequent elongation. Inhibition of DNA‐PK catalytic subunit reduced the occupancy of Pol II, S2 Pol II, and γH2AX in the gene bodies of transcriptionally activated genes. We have also shown that the DNA breaks were the resultant of transcriptional activation because interfering P‐TEFb using a small molecule reduced γH2AX accumulation. In addition, we have revealed the important function of topoisomerase II‐mediated DNA double strand breaks in Pol II pause release and processive elongation in stimulus‐inducible genes. A chemical inhibitor for the catalytic activity of topoisomerase II led to retention of Pol II in the transcription start site, interfered with Pol II pause release, and reduced the level of γH2AX on the activated genes. Our findings suggest DNA breaks mediated by topoisomerase II and DDR signaling involving TRIM28 and DNA‐PK as a novel transcriptional mechanism to regulate the expression of a number of stimulus‐inducible protein‐coding genes in humans.