P-TEFb Activation by RBM7 Shapes a Pro-survival Transcriptional Response to Genotoxic Stress

Andrii Bugai,Alexandre J.C Quaresma,Caroline C Friedel,Tina Lenasi,Robert Düster,Christopher R Sibley,Koh Fujinaga,Petra Kukanja,Thomas Hennig,Melanie Blasius,Matthias Geyer,Jernej Ule,Lars Dölken,Matjaž Barborič

doi:10.1016/j.molcel.2019.01.033

Abstract

SummaryDNA damage response (DDR) involves dramatic transcriptional alterations, the mechanisms of which remain ill defined. Here, we show that following genotoxic stress, the RNA-binding motif protein 7 (RBM7) stimulates RNA polymerase II (Pol II) transcription and promotes cell viability by activating the positive transcription elongation factor b (P-TEFb) via its release from the inhibitory 7SK small nuclear ribonucleoprotein (7SK snRNP). This is mediated by activation of p38MAPK, which triggers enhanced binding of RBM7 with core subunits of 7SK snRNP. In turn, P-TEFb relocates to chromatin to induce transcription of short units, including key DDR genes and multiple classes of non-coding RNAs. Critically, interfering with the axis of RBM7 and P-TEFb provokes cellular hypersensitivity to DNA-damage-inducing agents due to activation of apoptosis. Our work uncovers the importance of stress-dependent stimulation of Pol II pause release, which enables a pro-survival transcriptional response that is crucial for cell fate upon genotoxic insult.

Highlights

The cellular DNA damage response (DDR) has evolved to detect and repair lesions that are generated continuously by external and internal DNA-damaging agents (Hoeijmakers, 2009)
We focused our efforts on the ubiquitously expressed RNA-binding motif protein 7 (RBM7), which promotes survival of cells following DNA damage generated by UV or its mimicking genotoxic and carcinogenic chemical 4-nitroquinoline 1-oxide (4-NQO) (Blasius et al, 2014)
Consistent with the previous report (Lubas et al, 2015), RBM7 bound directly a diverse set of RNAs, including genic, intergenic, and non-coding RNAs (Figures 1A, S1A, and S1B; Table S1A). We ranked these RNAs by the change in binding following 4-NQO exposure, which showed increased RBM7 binding to snRNAs, including 7SK, spliceosomal snRNAs, and other ncRNAs, and decreased RBM7 binding to specific pre-mRNAs (Tables S1B and S1C)

Summary

Introduction

The cellular DNA damage response (DDR) has evolved to detect and repair lesions that are generated continuously by external and internal DNA-damaging agents (Hoeijmakers, 2009). It is widely accepted that cells need to shut down RNA polymerase II (Pol II) transcription in response to UV-induced bulky DNA lesions and other types of DNA damage, which can facilitate repair and limit the production of abnormal transcripts (Giono et al, 2016). While transcription can be inhibited transiently at the initiation and elongation stages (Awwad et al, 2017; Rockx et al, 2000; Williamson et al, 2017) or irreversibly through degradation of stalled Pol II (Wilson et al, 2013), it is eventually restored once the damage is corrected. The significance of mounting transcriptional activation following genotoxic stress remains poorly understood

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Discussion

Conclusion