Diabetic downregulation of Nrf2 activity via ERK contributes to oxidative stress-induced insulin resistance in cardiac cells in vitro and in vivo.
Diabetes
; 60(2): 625-33, 2011 Feb.
Article
en En
| MEDLINE
| ID: mdl-21270272
ABSTRACT
OBJECTIVE:
Oxidative stress is implicated in cardiac insulin resistance, a critical risk factor for cardiac failure, but the direct evidence remains missing. This study explored a causal link between oxidative stress and insulin resistance with a focus on a regulatory role of redox sensitive transcription factor NF-E2-related factor 2 (Nrf2) in the cardiac cells in vitro and in vivo. RESEARCH DESIGN ANDMETHODS:
Chronic treatment of HL-1 adult cardiomyocyte with hydrogen peroxide led to insulin resistance, reflected by a significant suppression of the insulin-induced glucose uptake. This was associated with an exaggerated phosphorylation of extracellular signal-related kinase (ERK). Although U0126, an ERK inhibitor, enhanced insulin sensitivity and attenuated oxidative stress-induced insulin resistance, LY294002, an inhibitor of phosphoinositide 3-kinase (PI3K), worsened the insulin resistance. Moreover, insulin increased Nrf2 transcriptional activity, which was blocked by LY294002 but enhanced by U0126. Forced activation of Nrf2 by adenoviral over-expression of Nrf2 inhibited the increased ERK activity and recovered the blunted insulin sensitivity on glucose uptake in cardiomyocytes that were chronically treated with H(2)O(2). In the hearts of streptozotocin-induced diabetic mice and diabetic patients Nrf2 expression significantly decreased along with significant increases in 3-nitrotyrosine accumulation and ERK phosphorylation, whereas these pathogenic changes were not observed in the heart of diabetic mice with cardiac-specific overexpression of a potent antioxidant metallothionein. Upregulation of Nrf2 by its activator, Dh404, in cardiomyocytes in vitro and in vivo prevented hydrogen peroxide- and diabetes-induced ERK activation and insulin-signaling downregulation.CONCLUSIONS:
ERK-mediated suppression of Nrf2 activity leads to the oxidative stress-induced insulin resistance in adult cardiomyocytes and downregulated glucose utilization in the diabetic heart.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Resistencia a la Insulina
/
Regulación hacia Abajo
/
Estrés Oxidativo
/
Miocitos Cardíacos
/
Quinasas MAP Reguladas por Señal Extracelular
/
Diabetes Mellitus
/
Factor 2 Relacionado con NF-E2
/
Insulina
/
Miocardio
Tipo de estudio:
Risk_factors_studies
Límite:
Animals
/
Humans
Idioma:
En
Revista:
Diabetes
Año:
2011
Tipo del documento:
Article
País de afiliación:
China