Molecular mechanisms underlying the apoptotic effect of KCNB1 K+ channel oxidation.
J Biol Chem
; 288(6): 4128-34, 2013 Feb 08.
Article
em En
| MEDLINE
| ID: mdl-23275378
ABSTRACT
Potassium (K(+)) channels are targets of reactive oxygen species in the aging nervous system. KCNB1 (formerly Kv2.1), a voltage-gated K(+) channel abundantly expressed in the cortex and hippocampus, is oxidized in the brains of aging mice and of the triple transgenic 3xTg-AD mouse model of Alzheimer's disease. KCNB1 oxidation acts to enhance apoptosis in mammalian cell lines, whereas a KCNB1 variant resistant to oxidative modification, C73A-KCNB1, is cytoprotective. Here we investigated the molecular mechanisms through which oxidized KCNB1 channels promote apoptosis. Biochemical evidence showed that oxidized KCNB1 channels, which form oligomers held together by disulfide bridges involving Cys-73, accumulated in the plasma membrane as a result of defective endocytosis. In contrast, C73A-mutant channels, which do not oligomerize, were normally internalized. KCNB1 channels localize in lipid rafts, and their internalization was dynamin 2-dependent. Accordingly, cholesterol supplementation reduced apoptosis promoted by oxidation of KCNB1. In contrast, cholesterol depletion exacerbated apoptotic death in a KCNB1-independent fashion. Inhibition of raft-associating c-Src tyrosine kinase and downstream JNK kinase by pharmacological and molecular means suppressed the pro-apoptotic effect of KCNB1 oxidation. Together, these data suggest that the accumulation of KCNB1 oligomers in the membrane disrupts planar lipid raft integrity and causes apoptosis via activating the c-Src/JNK signaling pathway.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Envelhecimento
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Apoptose
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Sistema de Sinalização das MAP Quinases
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Microdomínios da Membrana
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Canais de Potássio Shab
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Multimerização Proteica
Limite:
Animals
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article