Discovery of proteins and pathways contributing to TDP-43-mediated neurodegeneration in a novel transgenic mouse model of disease

Motor neuron disease (MND)/amyotrophic lateral sclerosis (ALS) is an incurable and fatal neurodegenerative disease caused by progressive loss of motor neurons controlling movement. The main pathology exhibited by 97% of ALS cases is the aggregation of the RNA/DNA-binding protein TDP-43 within the cytoplasm of affected neurons. Although ALS pathology is characterised by TDP-43 accumulation, it is not understood how this dysfunction causes disease, meaning that it has not been possible to design disease-modifying therapeutics. To combat this issue, a new transgenic mouse model was created to develop the disease as presented in humans which exhibits both pathology as well as a disease phenotype very similar to human ALS. Using the new transgenic mouse model, a large-scale advanced quantitative mass spectrometry (SWATH-MS) study was performed to discover the protein changes involved in TDP-43-mediated pathogenesis. Mass spectrometry results were analysed using several methods ranging from singular protein analysis (Uniprot), to comprehensive analyses (Ingenuity Pathway Analysis). Quantitative immunoblotting and immunofluorescence was used to validate mass spectrometry results. Identified the proteins and pathways which changed during disease course within NLS TDP-43 mice model of ALS. Two key proteins, COQ9 and IMA3, which are involved in known mechanisms of ALS pathogenesis were validated using immunoblotting. In addition, the canonical pathways, upstream regulators and biological function involved in rNLS TDP-43 pathology were comprehensively identified. This study provides important insights into TDP-43-mediated ALS neurodegeneration.