Motor neuron disease-associated loss of nuclear TDP-43 is linked to DNA double-strand break repair defects

• Published in: Proceedings of the National Academy of Sciences - PNAS 2019-03, Vol.116 (10), p.4696-4705
• Main Authors: Mitra, Joy, Guerrero, Erika N., Hegde, Pavana M., Liachko, Nicole F., Wang, Haibo, Vasquez, Velmarini, Gao, Junling, Pandey, Arvind, Taylor, J. Paul, Kraemer, Brian C., Wu, Ping, Boldogh, Istvan, Garruto, Ralph M., Mitra, Sankar, Rao, K. S., Hegde, Muralidhar L.
• Format: Article
• Language: English
• Subjects: Abnormalities; Accumulation; Amyotrophic lateral sclerosis; Amyotrophic Lateral Sclerosis - genetics; Amyotrophic Lateral Sclerosis - metabolism; Animals; Biological Sciences; Caenorhabditis elegans; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; CRISPR; Critical components; Damage accumulation; Defects; Deoxyribonucleic acid; Depletion; DNA; DNA Breaks, Double-Stranded; DNA damage; DNA End-Joining Repair; DNA Repair; DNA-binding protein; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Double-strand break repair; Etiology; Genomes; Genomic instability; Humans; Motor neuron diseases; Motor neurone disease; Motor Neurons - metabolism; Neurons; Non-homologous end joining; Pathology; Patients; Pluripotency; PNAS Plus; Protein Binding; Proteins; Repair; Ribonucleic acid; RNA; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; Sensitizing; Stability; Stem cells; Toxicity; Yeast
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1818415116

Genome damage and their defective repair have been etiologically linked to degenerating neurons in many subtypes of amyotrophic lateral sclerosis (ALS) patients; however, the specific mechanisms remain enigmatic. The majority of sporadic ALS patients feature abnormalities in the transactivation response DNA-binding protein of 43 kDa (TDP-43), whose nucleo-cytoplasmic mislocalization is characteristically observed in spinal motor neurons. While emerging evidence suggests involvement of other RNA/DNA binding proteins, like FUS in DNA damage response (DDR), the role of TDP-43 in DDR has not been investigated. Here, we report that TDP-43 is a critical component of the nonhomologous end joining (NHEJ)-mediated DNA double-strand break (DSB) repair pathway. TDP-43 is rapidly recruited at DSB sites to stably interact with DDR and NHEJ factors, specifically acting as a scaffold for the recruitment of break-sealing XRCC4-DNA ligase 4 complex at DSB sites in induced pluripotent stem cell-derived motor neurons. shRNA or CRISPR/Cas9-mediated conditional depletion of TDP-43 markedly increases accumulation of genomic DSBs by impairing NHEJ repair, and thereby, sensitizing neurons to DSB stress. Finally, TDP-43 pathology strongly correlates with DSB repair defects, and damage accumulation in the neuronal genomes of sporadic ALS patients and in Caenorhabditis elegans mutant with TDP-1 loss-of-function. Our findings thus link TDP-43 pathology to impaired DSB repair and persistent DDR signaling in motor neuron disease, and suggest that DSB repair-targeted therapies may ameliorate TDP-43 toxicity-induced genome instability in motor neuron disease.