title: Functional and molecular defects of hiPSC-derived neurons from patients with ATM deficiency.
abstract: Loss of ataxia telangiectasia mutated (ATM) kinase, a key factor of the DNA damage response (DDR) pathway, causes the cancer predisposing and neurodegenerative syndrome ataxia-telangiectasia (A-T). To investigate the mechanisms of neurodegeneration, we have reprogrammed fibroblasts from ATM-null A-T patients and normal controls to pluripotency (human-induced pluripotent stem cells), and derived from these neural precursor cells able to terminally differentiate into post-mitotic neurons positive to >90% for β-tubulin III+/microtubule-associated protein 2+. We show that A-T neurons display similar voltage-gated potassium and sodium currents and discharges of action potentials as control neurons, but defective expression of the maturation and synaptic markers SCG10, SYP and PSD95 (postsynaptic density protein 95). A-T neurons exhibited defective repair of DNA double-strand breaks (DSBs) and repressed phosphorylation of ATM substrates (e.g., γH2AX, Smc1-S966, Kap1-S824, Chk2-T68, p53-S15), but normal repair of single-strand breaks, and normal short- and long-patch base excision repair activities. Moreover, A-T neurons were resistant to apoptosis induced by the genotoxic agents camptothecin and trabectedin, but as sensitive as controls to the oxidative agents. Most notably, A-T neurons exhibited abnormal accumulation of topoisomerase 1-DNA covalent complexes (Top1-ccs). These findings reveal that ATM deficiency impairs neuronal maturation, suppresses the response and repair of DNA DSBs, and enhances Top1-cc accumulation. Top1-cc could be a risk factor for neurodegeneration as they may interfere with transcription elongation and promote transcriptional decline.
authors.affiliation: Department of Experimental Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Via Amadeo 42, 20133 Milano, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Carlessi
authors.affiliation: Department of Experimental Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Via Amadeo 42, 20133 Milano, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Fusar Poli
authors.affiliation: Department of Neurophysiopathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Via Amadeo 42, 20133 Milano, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Bechi
authors.affiliation: 1] Department of Neurophysiopathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Via Amadeo 42, 20133 Milano, Italy [2] Institute of Molecular and Cellular Pharmacology (IPMC) CNRS UMR7275 and University of Nice-Sophia Antipolis, 660 Route des Lucioles, 06560 Valbonne, France.
authors.forename: M
authors.initials: M
authors.lastname: Mantegazza
authors.affiliation: CNR Institute of Crystallography, Via Salaria, Km. 29.300, 00016 Monterotondo Scalo, Roma, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Pascucci
authors.affiliation: Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Narciso
authors.affiliation: Department of Environment and Primary Prevention, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Dogliotti
authors.affiliation: CNR Institute of Neuroscience and Department of Biotechnology and Translational Medicine, Via Vanvitelli 32, 20129 Milano, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Sala
authors.affiliation: CNR Institute of Neuroscience and Department of Biotechnology and Translational Medicine, Via Vanvitelli 32, 20129 Milano, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Verpelli
authors.affiliation: Department of Experimental Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Via Amadeo 42, 20133 Milano, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Lecis
authors.affiliation: Department of Experimental Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Via Amadeo 42, 20133 Milano, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Delia
mesh_terms: D001260:Ataxia Telangiectasia / Q000201:enzymology* / Q000235:genetics / Q000503:physiopathology; D064007:Ataxia Telangiectasia Mutated Proteins / Q000172:deficiency* / Q000235:genetics; D002478:Cells, Cultured; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology / Q000201:enzymology*; D008565:Membrane Proteins; D008938:Mitosis; D009474:Neurons / Q000166:cytology / Q000201:enzymology*; D010766:Phosphorylation; D050777:Stathmin
chemical_list: D008565:Membrane Proteins; C063314:STMN2 protein, human; D050777:Stathmin; D064007:Ataxia Telangiectasia Mutated Proteins; D004264:DNA Topoisomerases, Type I; C528909:TOP1 protein, human