J Korean Diabetes Assoc.  2003 Dec;27(6):456-466.

The Inhibitory Effect of Epicatechin on IL-1beta -induced iNOS Expression and NO Production in RINm5F Cell

• Ryu GR
• Min DS
• Rhie DJ
• Yoon SH
• Hahn SJ
• Kim MS
• Jo YH
• Kim MJ

Abstract

BACKGROUND: Interleukin-1beta (IL-1beta ) stimulates the expression of inducible nitric oxide synthase (iNOS) and the production of nitric oxide (NO), lead to NO-mediated insulin, which produces cell damage. Within these signal pathways, nuclear factor-kappaB (NF-kappaB) activation is crucial, with many IL-1beta -sensitive genes containing NF-kappaB binding sites in their promoter regions. The inhibitory effect of (-)epicatechin (EC), an antioxidant agent, on IL-1beta -induced NF-kappaB activation, and the subsequent iNOS expression in RINm5F cells, were examined. METHODS: RINm5F cells were pretreated with EC (0.8 mM), and then cultured with IL-1beta (10U/mL), and the iNOS mRNA and protein levels then determined by Northern and Western blots, respectively. The production of NO was measured as nitrite in the culture supernatant. The protein levels of the inhibitor of nuclear factor kappaB (IkappaB) and NF-kappaB DNA binding activity were determined by Western blot and electrophoretic mobility shift assay, respectively. Also, the promoter activity following transient transfection of the iNOS promoter-luciferase reporter genes into the cells were tested. RESULTS: EC was found to significantly reduce the IL-1beta -induced NO production, and iNOS protein and mRNA levels, and also blocked the IL-1beta -induced IkappaB protein degradation, NF-kappaB activation and iNOS promoter activity. CONCLUSION: These results suggest that EC inhibits the IL-1beta -induced iNOS expression in RINm5F cells, by interfering with the binding of the NF-kappaB to the iNOS promoter, thereby inhibiting the induction of iNOS transcription.

Keyword

Interleukin-1beta; RINm5F; Epicathechin; iNOS; NF-kappaB

MeSH Terms

Binding Sites
Blotting, Western
Catechin*
DNA
Electrophoretic Mobility Shift Assay
Genes, Reporter
Insulin
Interleukin-1beta
NF-kappa B
Nitric Oxide
Nitric Oxide Synthase Type II
Promoter Regions, Genetic
Proteolysis
RNA, Messenger
Signal Transduction
Transfection
Catechin
DNA
Insulin
Interleukin-1beta
NF-kappa B
Nitric Oxide
Nitric Oxide Synthase Type II
RNA, Messenger