Matrin 3 is a component of neuronal cytoplasmic inclusions of motor neurons in sporadic amyotrophic lateral sclerosis

5 years ago

Matrin 3 is a component of neuronal cytoplasmic inclusions of motor neurons in sporadic amyotrophic lateral sclerosis

Mutations in the matrin 3 (MATR3) gene have been identified as a cause of familial amyotrophic lateral sclerosis, but the involvement of MATR3 protein in sporadic amyotrophic lateral sclerosis (SALS) pathology has not been fully assessed. Here, we immunohistochemically analyzed MATR3 pathology in the spinal cords of SALS and control autopsies. MATR3 immunostaining of the motor neuron nuclei revealed two distinct patterns, mild and strong staining. There were no differences in the ratio of mild versus strong nuclear staining between the SALS and control cases. MATR3-containing neuronal cytoplasmic inclusions (NCIs) were observed in 60% of SALS cases. Most motor neurons with MATR3-positive NCIs exhibited a mild nuclear staining pattern. Although 16.8% of NCIs positive for TDP-43 were estimated as double-labeled by MATR3, no MATR3-positive/TDP-43–negative NCIs were observed. Although a previous study showed that MATR3-positive NCIs are present only in cases with C9orf72 hexanucleotide repeat expansion, ubiquitin-positive granular NCIs were not observed in the cerebellum, which have been reported as specific to C9orf72-related ALS. Six of the ALS cases were confirmed to be negative for the GGGGCC hexanucleotide. Our results reveal that MATR3 is a component of TDP-43–positive NCIs in motor neurons, even in SALS, and indicate the broader involvement of MATR3 in ALS pathology and the heterogeneity of TDP-43–positive NCIs.

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DOI: S0002944017309409