The catalytic subunit of protein phosphatase 2A (PP2Ac) promotes DNA hypomethylation by suppressing the phosphorylated mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)/phosphorylated ERK/DNMT1 protein pathway in T-cells from controls and systemic lupus erythematosus patients.
J Biol Chem
; 288(30): 21936-44, 2013 Jul 26.
Article
em En
| MEDLINE
| ID: mdl-23775084
ABSTRACT
DNA hypomethylation is a characteristic feature of systemic lupus erythematosus (SLE) immune cells. Numerous reports have implicated the involvement of the MEK/ERK pathway in the reduction of DNA methyltransferase (DNMT) expression, hence inducing the transcription of methylation-sensitive genes in SLE patients. However, the molecular mechanisms involved remain unclear. Here, we investigated whether the catalytic subunit of protein phosphatase 2A (PP2Ac), which is overexpressed in SLE T-cells, contributes to reduced DNA methylation. We show that both chemical suppression and siRNA silencing of PP2Ac in T-cells resulted in sustained phosphorylation of MEK and ERK following stimulation with phorbol 12-myristate 13-acetate and ionomycin. Furthermore, PP2Ac suppression resulted in increased DNMT enzyme activity, DNA hypermethylation, and decreased expression of methylation-sensitive genes. Similarly, in SLE T-cells, suppression of PP2Ac resulted in increased MEK/ERK phosphorylation, enhanced DNMT1 expression and suppressed expression of the methylation-sensitive CD70 gene. Our results demonstrate that PP2A regulates DNA methylation by influencing the phosphorylation of MEK/ERK. We propose that enhanced PP2Ac in SLE T-cells may dephosphorylate and activate the signaling pathway upstream of DNMT1, thus disturbing the tight control of methylation-sensitive genes, which are involved in SLE pathogenesis.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Linfócitos T
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Proteínas Quinases Ativadas por Mitógeno
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MAP Quinases Reguladas por Sinal Extracelular
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DNA (Citosina-5-)-Metiltransferases
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Proteína Fosfatase 2
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Lúpus Eritematoso Sistêmico
Limite:
Adult
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Female
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Humans
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Middle aged
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Estados Unidos