Gains or losses: molecular mechanisms of TDP43-mediated neurodegeneration

The involvement of the RNA-binding protein TDP43 in neurodegenerative disorders, including amyotrophic lateral sclerosis and frontotemporal lobar degeneration, has become well established. However, the mechanisms by which the protein is linked to the disease process remain unclear. Trojanowski and colleagues describe our current understanding of TDP43 pathology and discuss how gains of toxic function or losses of normal TDP43 function may contribute to neurodegeneration. RNA-binding proteins, and in particular TAR DNA-binding protein 43 (TDP43), are central to the pathogenesis of motor neuron diseases and related neurodegenerative disorders. Studies on human tissue have implicated several possible mechanisms of disease and experimental studies are now attempting to determine whether TDP43-mediated neurodegeneration results from a gain or a loss of function of the protein. In addition, the distinct possibility of pleotropic or combined effects — in which gains of toxic properties and losses of normal TDP43 functions act together — needs to be considered.