| Affiliation: | 1. UCL Institute of Neurology, and MRC Centre for Neuromuscular Disease, London, UKThese authors contributed equally to this workThese authors contributed equally to this work;2. Unidad de Investigación, Hospital Universitario de Canarias, Fundación Canaria de Investigación Sanitaria and Instituto de Tecnologías Biomédicas (CIBICAN), La Laguna, Spain;3. UCL Institute of Neurology, and MRC Centre for Neuromuscular Disease, London, UK;4. UCL Centre for Advanced Biomedical Imaging, University College London, London, UK;5. Graduate Program in Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, USA;6. MRC Mary Lyon Centre, Harwell, UK;7. MRC Mammalian Genetics Unit, Harwell, UK;8. UCL Genetics Institute, London, UK;9. Mutagenesis and Genomics Team, RIKEN BioResource Center, Tsukuba, Ibaraki, Japan;10. UCL Institute of Child Health, London, UK;11. UCL Institute of Neurology and Francis Crick Institute, London, UK;12. Rita Levi Montalcini Department of Neuroscience, University of Turin, Turin, Italy;13. UK Dementia Research Institute at UCL, UCL Institute of Neurology, London, UK;14. Department of Molecular Pharmacology, Physiology & Biotechnology, Brown University, Providence, RI, USA;15. Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA;16. International Center for Genomic Engineering and Biotechnology (ICGEB), Trieste, Italy;17. Unidad de Investigación, Hospital Universitario de Canarias, Fundación Canaria de Investigación Sanitaria and Instituto de Tecnologías Biomédicas (CIBICAN), La Laguna, SpainThese authors contributed equally to this work |
| Abstract: | TDP‐43 (encoded by the gene TARDBP) is an RNA binding protein central to the pathogenesis of amyotrophic lateral sclerosis (ALS). However, how TARDBP mutations trigger pathogenesis remains unknown. Here, we use novel mouse mutants carrying point mutations in endogenous Tardbp to dissect TDP‐43 function at physiological levels both in vitro and in vivo. Interestingly, we find that mutations within the C‐terminal domain of TDP‐43 lead to a gain of splicing function. Using two different strains, we are able to separate TDP‐43 loss‐ and gain‐of‐function effects. TDP‐43 gain‐of‐function effects in these mice reveal a novel category of splicing events controlled by TDP‐43, referred to as “skiptic” exons, in which skipping of constitutive exons causes changes in gene expression. In vivo, this gain‐of‐function mutation in endogenous Tardbp causes an adult‐onset neuromuscular phenotype accompanied by motor neuron loss and neurodegenerative changes. Furthermore, we have validated the splicing gain‐of‐function and skiptic exons in ALS patient‐derived cells. Our findings provide a novel pathogenic mechanism and highlight how TDP‐43 gain of function and loss of function affect RNA processing differently, suggesting they may act at different disease stages. |
