Inulin stimulates NO synthesis via activation of PKC-alpha and protein tyrosine kinase, resulting in the activation of NF-kappaB by IFN-gamma-primed RAW 264.7 cells.
Inulin, an active component of Chicorium intybus root, has been shown to stimulate the growth of bifidobacteria, and inhibit colon carcinogenesis. NO mediates a number of the host-defense functions of activated macrophages, including antimicrobial and tumoricidal activity. We examined the effect of inulin on the synthesis of NO in RAW 264.7 cells. Inulin alone had no effect, whereas inulin with IFN-gamma synergistically increased the NO production and inducible NO synthase (iNOS) expression in RAW 264.7 cells. Synergy between IFN-gamma and inulin was mainly dependent on inulin-induced TNF-alpha secretion. Also, protein kinase C (PKC)-alpha was involved in the inulin-induced NO production. Inulin-mediated NO production was inhibited by the protein tyrosine kinase (PTK) inhibitor, tyrphostin AG126. Since iNOS gene transcriptions have been shown to be under the control of the NF-kappaB/Rel family of transcription factors, we assessed the effect of inulin on NF-kappaB/Rel using an EMSA. Inulin produced strong induction of NF-kappaB/Rel binding, whereas AP-1 binding was slightly induced in RAW 264.7 cells. Inulin stimulated phosphorylation and degradation of IkappaB-alpha. These results suggest that in IFN-gamma-primed RAW 264.7 cells inulin might stimulate NO synthesis via activation of PKC-alpha and PTK, resulting in the activation of NF-kappaB.
Koo
Hyun-Na
HN
Department of Pharmacology, College of Oriental Medicine, Kyung Hee University, 1 Hoegi-Dong, Dongdaemun-Gu, 130-701, Seoul, South Korea.
Hong
Seung-Heon
SH
Seo
Han-Geuk
HG
Yoo
Taek-Soo
TS
Lee
Ki-Nam
KN
Kim
Nam-Song
NS
Kim
Cheorl-Ho
CH
Kim
Hyung-Min
HM
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D004789:Enzyme Activation; D007328:Insulin / Q000494:pharmacology*; D007371:Interferon-gamma / Q000494:pharmacology*; D007444:Inulin / Q000502:physiology; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D051379:Mice; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II; D011493:Protein Kinase C / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020032:Tyrphostins / Q000494:pharmacology
D007328:Insulin; D014409:Tumor Necrosis Factor-alpha; D020032:Tyrphostins; C482020:tyrphostin AG 126; D009569:Nitric Oxide; D007371:Interferon-gamma; D007444:Inulin; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D011505:Protein-Tyrosine Kinases; C496630:Prkca protein, mouse; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha