Zebrafish are an established vertebrate model and have been used in numerous studies to investigate MND/ALS. In order to investigate the pathomechanisms involved in fALS we generated zebrafish lines expressing either wild type or mutant human FUS. In our approach, using primary cell cultures derived from human FUS-GFP transgenic zebrafish, we aimed to investigate the susceptibility of motor neurons relative to all other cells to mislocalize FUS-GFP, generate SGs and recover from applied stress. This zebrafish cell model enables measurement of the extent and effects of FUS mislocalization, generation of inclusions in motor neurons and supporting cells within the same cultures where FUSGFP is ubiquitously expressed.It is unclear why FUS containing SG inclusions can form in all cells, but in the disease, the motor neurons specifically degenerate. Mislocalisation of FUS and inclusion formation may be TC-G 1001 insufficient alone to confer toxicity. Other factors RS 45041-190 hydrochloride specific to motor neurons or their circuitry could play additional roles in the disease process. Mislocalization of FUS protein and dysfunction of supporting cells could affect motor neuron function non-cell autonomously as has been demonstrated for other proteins such as SMN and SOD1. The transgenic lines reported here will enable these questions to be asked in future work. It also remains possible that chronic exposure to ALS-linked stresses and the ALS cellular pathology are necessary to breach an unknown threshold triggering cellautonomous death in later life. Alternatively, the generation of FUS inclusions in select neurons in the human disease may not in itself be toxic, but rather it could represent a marker of another non-cell autonomous neurotoxic process directed specifically at neurons or their circuitry as has been proposed for TDP43, SOD1 and SMN. FUS mislocalization and accumulation in assembled SGs demonstrated here is consistent with previous studies of mutant human FUS sub-cellular localization in mammalian cell lines and supports the use of the zebrafish model for investigating the cellular physiology of FUS in motor neuron disease. The R521C mutation is one of the most common fALS mutations and has been reported to cause relatively less aggressive forms of the disease compared to other mutations like P525L and R522G.