Apolipoprotein E interrupts interleukin-1beta signaling in vascular smooth muscle cells.
Arterioscler Thromb Vasc Biol
; 27(7): 1610-7, 2007 Jul.
Article
em En
| MEDLINE
| ID: mdl-17510469
ABSTRACT
OBJECTIVES:
Apolipoprotein E (apoE) exerts antiatherogenic effects but precise mechanisms remain unclear. We here investigated the effect of apoE on intracellular signaling by interleukin-1beta (IL-1beta), a proinflammatory cytokine present in atherosclerotic lesions. METHODS ANDRESULTS:
IL-1beta-induced expression and activation of inducible nitric oxide synthase and cyclooxygenase-2 were inhibited by apoE in vascular smooth muscle cells (VSMCs). These inhibitory effects were linked to the suppression of both NF-kappaB and activating protein-1 (AP-1) transactivation, suggesting that the interruption of IL-1beta signaling occurs upstream of transcription factors. Studies in VSMCs overexpressing IL-1beta signaling intermediates revealed that NF-kappaB transactivation was inhibited by apoE in MyD88- and IRAK1- but not in TRAF6-transfected cells. Furthermore, apoE prevented IRAK1 phosphorylation and IRAK1-TRAF6 but not MyD88-IRAK1 complex formation. Inhibitory effects of apoE on IL-1beta signaling were abolished after silencing LDL receptor-related protein-1 (LRP1) expression with siRNA. In addition, inhibitors of adenylyl cyclase and protein kinase A (PKA) restored IL-1beta signaling in apoE-treated VSMCs, whereas apoE stimulated PKA activity. ApoE inhibited VSMC activation in response to IL-18 but not to tumor necrosis factor-alpha or polyinosinicpolycytidylic acid.CONCLUSION:
ApoE targets IRAK-1 activation and thereby interrupts IL-1beta and IL-18 signaling in VSMCs. This antiinflammatory effect represents a novel antiatherogenic activity of apoE.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Apolipoproteínas E
/
Ciclo-Oxigenase 2
/
Quinases Associadas a Receptores de Interleucina-1
/
Interleucina-1beta
/
Músculo Liso Vascular
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article