RESUMO
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the selective death of motor neurons. Causative mutations in the global RNA-processing proteins TDP-43 and FUS among others, as well as their aggregation in ALS patients, have identified defects in RNA metabolism as an important feature in this disease. Lethal congenital contracture syndrome 1 and lethal arthrogryposis with anterior horn cell disease are autosomal recessive fetal motor neuron diseases that are caused by mutations in another global RNA-processing protein, hGle1. In this study, we carried out the first screening of GLE1 in ALS patients (173 familial and 760 sporadic) and identified 2 deleterious mutations (1 splice site and 1 nonsense mutation) and 1 missense mutation. Functional analysis of the deleterious mutants revealed them to be unable to rescue motor neuron pathology in zebrafish morphants lacking Gle1. Furthermore, in HeLa cells, both mutations caused a depletion of hGle1 at the nuclear pore where it carries out an essential role in nuclear export of mRNA. These results suggest a haploinsufficiency mechanism and point to a causative role for GLE1 mutations in ALS patients. This further supports the involvement of global defects in RNA metabolism in ALS.
Assuntos
Esclerose Lateral Amiotrófica/genética , Códon sem Sentido , Mutação de Sentido Incorreto , Proteínas de Transporte Nucleocitoplasmático/genética , Esclerose Lateral Amiotrófica/patologia , Animais , Artrogripose/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Modelos Animais de Doenças , Haploinsuficiência/genética , Células HeLa , Humanos , Microscopia Confocal , Neurônios Motores/patologia , Poro Nuclear/genética , Poro Nuclear/metabolismo , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Linhagem , Processamento de Proteína Pós-Traducional , Splicing de RNA , RNA Mensageiro/metabolismo , Peixe-ZebraRESUMO
BACKGROUND: Substantial efforts have been deployed in the past decade to identify the genetic causes of amyotrophic lateral sclerosis (ALS), and we hypothesized here that mutations in SORT1 or aberrant SORT1 splicing reduce progranulin level and promote neurodegeneration. METHODS: We sequenced the coding exons of SORT1 in a cohort of 112 unrelated individuals with familial ALS. We also tested for aberrant SORT1 splicing by RT-PCR using RNA samples from cell lines expressing six different ALS-associated TARDBP mutations. RESULTS: We identified one unique missense and two unique silent mutations in our cohort. None are predicted to have functional effects. No aberrant SORT1 splicing event was observed. CONCLUSIONS: SORT1 mutations are not a common cause of familial ALS, and the influence of TARDBP mutations on SORT1 splicing still needs to be clarified.
