Korean J Physiol Pharmacol.
2001 Feb;5(1):55-63.
Role of NF- kappaB binding sites in the regulation of inducible nitric
oxide synthase by tyrosine kinase
- Affiliations
-
- 1Department of Pharmacology, College of Medicine, Chungnam National
University, 6 Munhwa-dong, Jung-gu, Taejon, South Korea.
gmhur@hanbat.chungnam.ac.kr
Abstract
- In macrophages, lipopolysaccharide (LPS) alone or in combination with
interferon- gamma (IFN- gamma) has been shown to release a nitric oxide
(NO) through the increase of the transcription of the inducible nitric
oxide synthase (iNOS) gene. To investigate the exact intracellular
signaling pathway of the regulation of iNOS gene transcription by LPS
plus IFN- gamma, the effects of protein tyrosine kinase (PTK) inhibitor
and protein kinase C (PKC) inhibitors on NO production, iNOS mRNA
expression, nuclear factor- kappaB (NF- kappaB) binding activity and
the promoter activity of iNOS gene containing two NF- kappaB sites have
been examined in a mouse macrophage RAW 264.7 cells. LPS or IFN- gamma,
stimulated NO production, and their effect was enhanced synergistically
by mixture of LPS and IFN- gamma. The PTK inhibitor such as tyrphostin
reduced LPS plus IFN- gamma-induced NO production, iNOS mRNA expression
and NF- kappaB binding activity. In contrast, PKC inhibitors such as
H-7, Ro-318220 and staurosporine did not show any effect on them. In
addition, transfection of RAW 264.7 cells with iNOS promoter linked to
a CAT reporter gene revealed that tyrphostin inhibited the iNOS
promoter activity through the NF- kappaB binding site, whereas PKC
inhibitors did not. Taken together, these suggest that PTK, but not PKC
pathway, is involved in the regulation of the iNOS gene transcription
through the NF- kappaB sites of iNOS promoter in RAW 264.7 macrophages
by LPS plus IFN- gamma.