RESUMO
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects motor neurons and lacks an effective treatment. The disease pathogenesis has not been clarified at present. Pathological transactive response DNA-binding protein 43 (TDP-43) plays an important role in the pathogenesis of ALS. Nuclear translocation of nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) is found in a mutant TDP-43 transgenic cell model, but its downstream antioxidant enzyme expression is decreased. To elucidate the specific mechanism of Nrf2/ARE (antioxidant responsive element) signaling dysfunction, we constructed an ALS cell model with human mutant TDP-43 using the NSC-34 cell line to evaluate the impact of the TDP-43 mutation on the Nrf2/ARE pathway. We found the nuclear translocation of Nrf2, but the expression of total Nrf2, cytoplasmic Nrf2, and downstream phase II detoxifying enzyme (NQO1) was decreased in NSC-34 cells transfected with the TDP-43-M337V plasmid. Besides, TDP-43-M337V plasmid-transfected NSC-34 cells were rounded with reduced neurites, shortened axons, increased levels of intracellular lipid peroxidation products, and decreased viability, which suggests that the TDP-43-M337V plasmid weakened the antioxidant capacity of NSC-34 cells and increased their susceptibility to oxidative damage. We further showed that expression of the MafK protein and the Jun dimerization protein 2 (JDP2) was reduced in TDP-43-M337V plasmid-transfected NSC-34 cells, which might cause accumulation of Nrf2 in nuclei but a decrease in NQO1 expression. Taken together, our results confirmed that TDP-43-M337V impaired the Nrf2/ARE pathway by reducing the expression of MafK and JDP2 proteins, and provided information for further research on the molecular mechanisms of TDP-43-M337V in ALS.
Assuntos
Esclerose Lateral Amiotrófica/metabolismo , Proteínas de Ligação a DNA/metabolismo , Fator de Transcrição MafK/metabolismo , Mutação de Sentido Incorreto , Fator 2 Relacionado a NF-E2/metabolismo , Proteínas Repressoras/metabolismo , Elementos de Resposta , Animais , Linhagem Celular , Proteínas de Ligação a DNA/genética , Fator de Transcrição MafK/genética , Camundongos , NAD(P)H Desidrogenase (Quinona)/metabolismo , Neurônios/metabolismo , Estresse Oxidativo , Proteínas Repressoras/genéticaRESUMO
The primary aims of this study were to investigate mitochondrial metabolism during experimental allergic encephalomyelitis (EAE) animal model axonal injury and to determine the correlation among neurological function scores, pathological changes, and the activities of the BB isoenzyme of creatine kinase (CK-BB), catalase (CAT), and calpain in the brain tissues of EAE rats. Another goal was to preliminarily define the mechanism of mitochondrial metabolism resulting from the effect of beta 2 adrenergic agonists in the process of EAE animal model axonal damage. EAE was induced in specific pathogen free Wistar rats by guinea pig spinal cord homogenate, complete Freund's adjuvant, and pertussis vaccine. We recorded the behavioral change in EAE rats, detected pathological changes in central nervous tissue, and observed the changes of the CK-BB, CAT, and calpain in the EAE rat brain and spinal cord. The results indicated that the average neurologic function score increased in the EAE group compared to that of the controls (P < 0.01). In addition, CAT and CK-BB activities significantly decreased and the calpain activity significantly increased compared with those of the control group (P < 0.05). The decrease of the activity of central nervous CK-BB and CAT content, as well as the increase of calpain activity at the highest time point were considered to be the consequences of EAE. Furthermore, the results revealed that use of salbutamol could alleviate disease symptoms and reduce the recurrence of the EAE disease.