title: Aggregation of ALS-linked FUS mutant sequesters RNA binding proteins and impairs RNA granules formation.
abstract: Protein aggregate/inclusion is one of hallmarks for neurodegenerative disorders including amyotrophic lateral sclerosis (ALS). FUS/TLS, one of causative genes for familial ALS, encodes a multifunctional DNA/RNA binding protein predominantly localized in the nucleus. C-terminal mutations in FUS/TLS cause the retention and the inclusion of FUS/TLS mutants in the cytoplasm. In the present study, we examined the effects of ALS-linked FUS mutants on ALS-associated RNA binding proteins and RNA granules. FUS C-terminal mutants were diffusely mislocalized in the cytoplasm as small granules in transiently transfected SH-SY5Y cells, whereas large aggregates were spontaneously formed in ∼10% of those cells. hnRNP A1, hnRNP A2, and SMN1 as well as FUS wild type were assembled into stress granules under stress conditions, and these were also recruited to FUS mutant-derived spontaneous aggregates in the cytoplasm. These aggregates stalled poly(A) mRNAs and sequestered SMN1 in the detergent insoluble fraction, which also reduced the number of nuclear oligo(dT)-positive foci (speckles) in FISH (fluorescence in situ hybridization) assay. In addition, the number of P-bodies was decreased in cells harboring cytoplasmic granules of FUS P525L. These findings raise the possibility that ALS-linked C-terminal FUS mutants could sequester a variety of RNA binding proteins and mRNAs in the cytoplasmic aggregates, which could disrupt various aspects of RNA equilibrium and biogenesis.
authors.affiliation: Department of Neurobiology, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Takanashi
authors.affiliation: Department of Neurobiology, Graduate School of Medicine, Chiba University, Chiba, Japan. Electronic address: atsyama@restaff.chiba-u.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamaguchi
mesh_terms: D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology; D003593:Cytoplasm / Q000378:metabolism / Q000473:pathology; D003594:Cytoplasmic Granules / Q000737:chemistry* / Q000378:metabolism / Q000473:pathology; D015870:Gene Expression; D057809:HEK293 Cells; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009154:Mutation; D009474:Neurons / Q000737:chemistry* / Q000378:metabolism / Q000473:pathology; D066329:Protein Aggregates; D066263:Protein Aggregation, Pathological / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D034702:RNA-Binding Protein FUS / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D055533:Survival of Motor Neuron 1 Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D066329:Protein Aggregates; D012333:RNA, Messenger; D034702:RNA-Binding Protein FUS; C526471:SMN1 protein, human; D055533:Survival of Motor Neuron 1 Protein; C439768:hnRNP A2
keywords: ALS; FUS/TLS; SMN1; hnRNP A/B