10779/crick.12652712.v1 Pietro Fratta Pietro Fratta Prasanth Sivakumar Prasanth Sivakumar Jack Humphrey Jack Humphrey Kitty Lo Kitty Lo Thomas Ricketts Thomas Ricketts Hugo Oliveira Hugo Oliveira Jose M Brito-Armas Jose M Brito-Armas Bernadett Kalmar Bernadett Kalmar Agnieszka Ule Agnieszka Ule Yichao Yu Yichao Yu Nicol Birsa Nicol Birsa Cristian Bodo Cristian Bodo Toby Collins Toby Collins Alexander E Conicella Alexander E Conicella Alan Mejia Maza Alan Mejia Maza Alessandro Marrero-Gagliardi Alessandro Marrero-Gagliardi Michelle Stewart Michelle Stewart Joffrey Mianne Joffrey Mianne Silvia Corrochano Silvia Corrochano Warren Emmett Warren Emmett Gemma Codner Gemma Codner Michael Groves Michael Groves Ryutaro Fukumura Ryutaro Fukumura Yoichi Gondo Yoichi Gondo Mark Lythgoe Mark Lythgoe Erwin Pauws Erwin Pauws Emma Peskett Emma Peskett Philip Stanier Philip Stanier Lydia Teboul Lydia Teboul Martina Hallegger Martina Hallegger Andrea Calvo Andrea Calvo Adriano Chiò Adriano Chiò Adrian M Isaacs Adrian M Isaacs Nicolas L Fawzi Nicolas L Fawzi Eric Wang Eric Wang David E Housman David E Housman Francisco Baralle Francisco Baralle Linda Greensmith Linda Greensmith Emanuele Buratti Emanuele Buratti Vincent Plagnol Vincent Plagnol Elizabeth MC Fisher Elizabeth MC Fisher Abraham Acevedo-Arozena Abraham Acevedo-Arozena Mice with endogenous TDP-43 mutations exhibit gain of splicing function and characteristics of amyotrophic lateral sclerosis The Francis Crick Institute 2020 ALS TDP‐43 cryptic exon skiptic exon splicing Alternative Splicing Amyotrophic Lateral Sclerosis Animals DNA-Binding Proteins Exons Gene Expression Regulation Humans Mice Motor Neurons Mutation RNA Splicing RNA-Binding Proteins Ule - sec 06 Biological Sciences 08 Information and Computing Sciences 11 Medical and Health Sciences Developmental Biology 2020-07-15 11:19:21 Journal contribution https://crick.figshare.com/articles/journal_contribution/Mice_with_endogenous_TDP-43_mutations_exhibit_gain_of_splicing_function_and_characteristics_of_amyotrophic_lateral_sclerosis/12652712 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.