Lipopolysaccharide (LPS)-stimulated iNOS induction is increased by glucosamine under normal glucose conditions but is inhibited by glucosamine under high glucose conditions in macrophage cells

Ji Sun Hwang, Mi Youn Kwon, Kyung Hong Kim, Yunkyoung Lee, In Kyoon Lyoo, Jieun E. Kim, Eok Soo Oh, Inn Oc Han

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

We investigated the regulatory effect of glucosamine (GlcN) for the production of nitric oxide (NO) and expression of inducible NO synthase (iNOS) under various glucose conditions in macrophage cells. At normal glucose concentrations, GlcN dose dependently increased LPS-stimulated production of NO/iNOS. However, GlcN suppressed NO/iNOS production under high glucose culture conditions. Moreover, GlcN suppressed LPS-induced up-regulation of COX-2, IL-6, and TNF-α mRNAs under 25 mM glucose conditions yet did not inhibit upregulation under 5 mM glucose conditions. Glucose itself dose dependently increased LPS-induced iNOS expression. LPS-induced MAPK and IκB-α phosphorylation did not significantly differ at normal and high glucose conditions. The activity of LPS-induced nuclear factor-κB (NF-κB) and DNA binding of c-Rel to the iNOS promoter were inhibited under high glucose conditions in comparison with no significant changes under normal glucose conditions. In addition, we found that the LPS-induced increase in O-GlcNAcylation as well as DNA binding of c-Rel to the iNOS promoter were further increased by GlcN under normal glucose conditions. However, both O-GlcNAcylation and DNA binding of c-Rel decreased under high glucose conditions. The NF-κB inhibitor, pyrrolidine dithiocarbamate, inhibited LPS-induced iNOS expression under high glucose conditions but it did not influence iNOS induction under normal glucose conditions. In addition, pyrrolidine dithiocarbamate inhibited NF-κB DNA binding and c-Rel O-GlcNAcylation only under high glucose conditions. By blocking transcription with actinomycin D, we found that stability of LPS-induced iNOSmRNAwas increased by GlcN under normal glucose conditions. These results suggest that GlcN regulates inflammation by sensing energy states of normal and fuel excess.

Original languageEnglish
Pages (from-to)1724-1736
Number of pages13
JournalJournal of Biological Chemistry
Volume292
Issue number5
DOIs
StatePublished - 3 Feb 2017

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