RESUMO
Motor neuron diseases (MNDs) are a group of neurodegenerative disorders with involvement of upper and/or lower motor neurons, such as amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), progressive bulbar palsy, and primary lateral sclerosis. Recently, we have mapped a new locus for an atypical form of ALS/MND (atypical amyotrophic lateral sclerosis [ALS8]) at 20q13.3 in a large white Brazilian family. Here, we report the finding of a novel missense mutation in the vesicle-associated membrane protein/synaptobrevin-associated membrane protein B (VAPB) gene in patients from this family. Subsequently, the same mutation was identified in patients from six additional kindreds but with different clinical courses, such as ALS8, late-onset SMA, and typical severe ALS with rapid progression. Although it was not possible to link all these families, haplotype analysis suggests a founder effect. Members of the vesicle-associated proteins are intracellular membrane proteins that can associate with microtubules and that have been shown to have a function in membrane transport. These data suggest that clinically variable MNDs may be caused by a dysfunction in intracellular membrane trafficking.
Assuntos
Esclerose Lateral Amiotrófica/genética , Proteínas de Ligação ao Cálcio/genética , Cromossomos Humanos Par 20/genética , Expressão Gênica , Atrofia Muscular Espinal/genética , Adulto , Sequência de Aminoácidos , Brasil , Células Cultivadas , Mapeamento Cromossômico , Primers do DNA , Efeito Fundador , Proteínas de Fluorescência Verde , Humanos , Proteínas Interatuantes com Canais de Kv , Pessoa de Meia-Idade , Modelos Moleculares , Dados de Sequência Molecular , Mutação de Sentido Incorreto/genética , Linhagem , Estrutura Terciária de Proteína , Alinhamento de Sequência , Análise de Sequência de DNA , Proteínas de Transporte VesicularRESUMO
The temporal course of cerebral cytokine gene expression was investigated in the ME7/CV murine scrapie model to determine any association with neuropathological events. Analysis by RNase protection assay (RPA) demonstrated no transcripts for ILs 2, 3, 4, 5, 6, 7, 10, 12p40 and 13, granulocyte macrophage colony-stimulating factor, IFN-gamma or lymphotoxin-alpha at any time during the course of this disease. Transcripts for transforming growth factor-beta 1 were constitutively expressed in both control and scrapie-infected brain and were elevated at terminal disease. RPA and quantitative real-time RT-PCR detected low levels of transcripts for IL-1 alpha, IL-1 beta and TNF alpha in scrapie-infected brain but only IL-1 beta was elevated consistently in all mice studied. Although glial cell activation within the hippocampus was evident from 100 days post-infection (p.i.), elevated IL-1 beta transcripts (and immunoreactivity) were evident from 180 days p.i., around the time of hippocampal pyramidal neuron loss, and increased steadily thereafter to reach a 3.5-fold increase at terminal disease. Even at their maximum, levels of these transcripts were disproportionately low relative to the degree of glial cell activation. It is concluded that cytokine gene expression in the ME7 scrapie-infected mouse brain, relative to the degree of reactive gliosis, is highly restricted, temporally late and disproportionately low.
