title: DNA-PK triggers histone ubiquitination and signaling in response to DNA double-strand breaks produced during the repair of transcription-blocking topoisomerase I lesions.
abstract: Although defective repair of DNA double-strand breaks (DSBs) leads to neurodegenerative diseases, the processes underlying their production and signaling in non-replicating cells are largely unknown. Stabilized topoisomerase I cleavage complexes (Top1cc) by natural compounds or common DNA alterations are transcription-blocking lesions whose repair depends primarily on Top1 proteolysis and excision by tyrosyl-DNA phosphodiesterase-1 (TDP1). We previously reported that stabilized Top1cc produce transcription-dependent DSBs that activate ATM in neurons. Here, we use camptothecin (CPT)-treated serum-starved quiescent cells to induce transcription-blocking Top1cc and show that those DSBs are generated during Top1cc repair from Top1 peptide-linked DNA single-strand breaks generated after Top1 proteolysis and before excision by TDP1. Following DSB induction, ATM activates DNA-PK whose inhibition suppresses H2AX and H2A ubiquitination and the later assembly of activated ATM into nuclear foci. Inhibition of DNA-PK also reduces Top1 ubiquitination and proteolysis as well as resumption of RNA synthesis suggesting that DSB signaling further enhances Top1cc repair. Finally, we show that co-transcriptional DSBs kill quiescent cells. Together, these new findings reveal that DSB production and signaling by transcription-blocking Top1 lesions impact on non-replicating cell fate and provide insights on the molecular pathogenesis of neurodegenerative diseases such as SCAN1 and AT syndromes, which are caused by TDP1 and ATM deficiency, respectively.
authors.affiliation: Cancer Research Center of Toulouse, INSERM UMR1037, Toulouse 31037, France.
authors.forename: Agnese
authors.initials: A
authors.lastname: Cristini
authors.affiliation: Cancer Research Center of Toulouse, INSERM UMR1037, Toulouse 31037, France.
authors.forename: Joon-Hyung
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Pharmacy and Biotechnology, University of Bologna, Bologna 40126, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Capranico
authors.affiliation: Université de Toulouse, UPS, LBCMCP, 31062 Toulouse, France CNRS, LBCMCP, 31062 Toulouse, France.
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Legube
authors.affiliation: Cancer Research Center of Toulouse, INSERM UMR1037, Toulouse 31037, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Favre
authors.affiliation: Cancer Research Center of Toulouse, INSERM UMR1037, Toulouse 31037, France olivier.sordet@inserm.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: Sordet
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics / Q000378:metabolism; D002166:Camptothecin / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D053903:DNA Breaks, Double-Stranded; D053904:DNA Breaks, Single-Stranded; D004260:DNA Repair; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism*; D051747:DNA-Activated Protein Kinase / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D008856:Microscopy, Fluorescence; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D015398:Signal Transduction; D059004:Topoisomerase I Inhibitors / Q000494:pharmacology; D054875:Ubiquitination / Q000187:drug effects
chemical_list: D016895:Culture Media, Serum-Free; D006657:Histones; D009687:Nuclear Proteins; D059004:Topoisomerase I Inhibitors; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D004264:DNA Topoisomerases, Type I; C528909:TOP1 protein, human; D002166:Camptothecin