P-TEFb activation by RBM7 shapes a pro-survival transcriptional response to genotoxic stress

Abstract

Cellular DNA damage response (DDR) involves dramatic transcriptional alterations, the mechanisms of which remain ill-defined. Given the centrality of RNA polymerase II (Pol II) promoter-proximal pause release in transcriptional control, we evaluated its importance in DDR. Here we show that following genotoxic stress, the RNA-binding motif protein 7 (RBM7) stimulates Pol II elongation and promotes cell viability by activating the positive transcription elongation factor b (P-TEFb). This is mediated by genotoxic stressenhanced binding of RBM7 to 7SK snRNA (7SK), the scaffold of the 7SK small nuclear ribonucleoprotein (7SK snRNP) which inhibits P-TEFb. In turn, P-TEFb relocates from 7SK snRNP to chromatin to induce transcription of short units including key DDR genes and multiple classes of noncoding RNAs. Critically, interfering with RBM7 or P-TEFb provokes cellular hypersensitivity to DNA damage-inducing agents through activation of apoptotic program. By alleviating the inhibition of P-TEFb, RBM7 thus facilitates Pol II elongation to enable a pro-survival transcriptional response that is crucial for cell fate upon genotoxic insult. Our work uncovers a new paradigm in stress-dependent control of Pol II pause release, and offers the promise for designing novel anti-cancer interventions using RBM7 and P-TEFb antagonists in combination with DNA-damaging chemotherapeutics.

RNA modifications detection by comparative Nanopore direct RNA sequencing

“…We also identified 5 significant overlapping kmers between positions 229 and 250 in the terminal loop of hairpin 3 (HP3) (Figure 5A,B). This region was recently shown to be the binding site for RNA-binding motif protein 7 (RBM7), which mediates the activation of P-TEFb by releasing it from 7SK snRNP 31 . We next sought to extend our investigation of 7SK to include other modifications in addition to m6A.…”

LARP7 is a BRCA1 ubiquitinase substrate and regulates genome stability and tumorigenesis

“…Bugai's study suggested 4-NQO induced RBM7's relocation to 7SK snRNP to releases pTEFb and promoted the cell survival, while the integration of 7SK snRNP remains unaffected throughout the response process (Bugai et al, 2019). We reasoned the difference is possibly because of the distinct genotoxic stressed applied in two studies.…”

“…7SK snRNP, although not directly associated with RNAPII, was also found to involve in DDR. A very recent study reported that the genotoxic chemical 4-nitroquinoline 1-oxide (4-NQO), a mimetic of UV inducing the nucleotide excision repair (NER), increased RNA-binding motif protein7 (RBM7) bind to 7SK snRNP, which in turn released pTEFb and promoted RNAPII pause release (Bugai et al, 2019).…”

Continuous transcription initiation guarantees robust repair of transcribed genes and regulatory regions in response to DNA damage

“…In this study, we provide quantitative insights into the molecular processes underlying the major transcriptioncoordinated cellular response that is activated in human cells upon genotoxic stress [28][29][30]38,41,54 . The establishment of precise maps of chromatin state helped us to query in detail the impact of transcription on DNA repair activities at important functional regions, including PROMPT and eRNA loci.…”

“…Moreover, depletion of the pre-initiating hypo-phosphorylated Pol II(-hypo) isoform from chromatin shortly after UV irradiation 28,32,33 has led to the assumption that new transcription initiation events are transiently and globally repressed [32][33][34][35][36][37] . On the other hand, recent reports 28,29,38 have revealed a functionally essential stress-dependent global increase in 5' nascent RNA (nRNA) activity that depends on the UV-induced raise in active P-TEFb levels 39,40 and on the rapid dissociation of the NELF complex 41 . The ensuing fast and global release of de novo Pol II elongation waves from PPP sites into gene bodies boosts lesion-sensing activity and accelerates removal of DNA adducts by TC-NER in virtually all active mRNA genes 28 .…”