RESUMO
Dysfunction of two structurally and functionally related proteins, FUS and TAR DNA-binding protein of 43 kDa (TDP-43), implicated in crucial steps of cellular RNA metabolism can cause amyotrophic lateral sclerosis (ALS) and certain other neurodegenerative diseases. The proteins are intrinsically aggregate-prone and form non-amyloid inclusions in the affected nervous tissues, but the role of these proteinaceous aggregates in disease onset and progression is still uncertain. To address this question, we designed a variant of FUS, FUS 1-359, which is predominantly cytoplasmic, highly aggregate-prone, and lacks a region responsible for RNA recognition and binding. Expression of FUS 1-359 in neurons of transgenic mice, at a level lower than that of endogenous FUS, triggers FUSopathy associated with severe damage of motor neurons and their axons, neuroinflammatory reaction, and eventual loss of selective motor neuron populations. These pathological changes cause abrupt development of a severe motor phenotype at the age of 2.5-4.5 months and death of affected animals within several days of onset. The pattern of pathology in transgenic FUS 1-359 mice recapitulates several key features of human ALS with the dynamics of the disease progression compressed in line with shorter mouse lifespan. Our data indicate that neuronal FUS aggregation is sufficient to cause ALS-like phenotype in transgenic mice.
Assuntos
Sequência de Aminoácidos , Esclerose Lateral Amiotrófica/metabolismo , Axônios/metabolismo , Neurônios Motores/metabolismo , Sinais de Localização Nuclear , Proteína FUS de Ligação a RNA/biossíntese , Deleção de Sequência , Motivos de Aminoácidos , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/patologia , Animais , Axônios/patologia , Citoplasma/genética , Citoplasma/metabolismo , Citoplasma/patologia , Humanos , Camundongos , Camundongos Transgênicos , Neurônios Motores/patologia , Fenótipo , RNA , Proteína FUS de Ligação a RNA/genéticaRESUMO
Mutations to the RNA binding protein, fused in sarcoma (FUS) occur in â¼5% of familial ALS and FUS-positive cytoplasmic inclusions are commonly observed in these patients. Altered RNA metabolism is increasingly implicated in ALS, yet it is not understood how the specificity with which FUS interacts with RNA in the cytoplasm can affect its aggregation in vivo. To further understand this, we expressed, in mice, a form of FUS (FUS ΔRRMcyt) that lacked the RNA recognition motif (RRM), thought to impart specificity to FUS-RNA interactions, and carried an ALS-associated point mutation, R522G, retaining the protein in the cytoplasm. Here we report the phenotype and results of histological assessment of the brain of transgenic mice expressing this isoform of FUS. Results demonstrated that neuronal expression of FUS ΔRRMcyt caused early lethality often preceded by severe tremor. Large FUS-positive cytoplasmic inclusions were found in many brain neurons; however, neither neuronal loss nor neuroinflammatory response was observed. In conclusion, the extensive FUS proteinopathy and severe phenotype of these mice suggests that affecting the interactions of FUS with RNA in vivo may augment its aggregation in the neuronal cytoplasm and the severity of disease processes.
Assuntos
Citoplasma/genética , Letargia/genética , Neurônios/patologia , Proteína FUS de Ligação a RNA/genética , Deleção de Sequência , Motivos de Aminoácidos , Animais , Encéfalo/patologia , Modelos Animais de Doenças , Progressão da Doença , Proteína Glial Fibrilar Ácida/metabolismo , Corpos de Inclusão/metabolismo , Corpos de Inclusão/patologia , Letargia/complicações , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Neurônios/metabolismo , Fosfopiruvato Hidratase/metabolismo , Proteína FUS de Ligação a RNA/metabolismo , Tremor/genética , Tremor/patologia , Tremor/fisiopatologiaRESUMO
Cohorts of amyotrophic lateral sclerosis (ALS) patients and control individuals of Caucasian origin from the Central European Russia (Moscow city and region) were analyzed for the presence of hexanucleotide repeat GGGGCC expansion within the first intron of the C9ORF72 gene. The presence of a large (>40) repeat expansion was found in 15% of familial ALS cases (3 of 20 unrelated familial cases) and 2.5% of sporadic ALS cases (6 of 238) but in none of control cases. These results suggest that the frequency of C9ORF72 hexanucleotide repeats expansions in the Central European Russian ALS patients is significantly lower than in Western European or Northern American ALS patients of Caucasian origin but higher than in Asian ALS patients.
Assuntos
Esclerose Lateral Amiotrófica/genética , Expansão das Repetições de DNA/genética , Proteínas/genética , Proteína C9orf72 , Estudos de Coortes , Europa (Continente) , Humanos , Íntrons/genética , Federação Russa , Expansão das Repetições de Trinucleotídeos , População BrancaRESUMO
This report discusses the newest approaches to rehabilitation of post-stroke patients. Recent studies have clinical implications for the treatment of stroke at all stages, and chronic aphasia.