Fructose-1,6-bisphosphate attenuates induction of nitric oxide synthase in microglia stimulated with lipopolysaccharide.
OBJECTIVE
Fructose-1,6-bisphosphate (FBP) is a glycolytic intermediate with neuroprotective action in various brain injury models. However, the mechanism underlying the neuroprotection of FBP has not been fully defined. In this study, we investigated whether FBP inhibits endotoxin-induced nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression in microglial cells and explored the possible mechanisms of the effects of FBP.


METHODS
Murine microglial cell line BV2 and primary cultured murine microglial cells were used. NO production and iNOS expression were determined by Griess reaction, RT-PCR and Western blot. Luciferase assay using iNOS promoter-luciferase (iNOS-Luc) construct was adopted for measuring transcriptional activity.


RESULTS
FBP dose-dependently suppressed lipopolysaccharide (LPS)-induced NO production, along with reducing the expression of iNOS at both the protein and mRNA level in primary cultured murine microglia and BV2 cells. FBP significantly inhibited iNOS promoter activity but stabilized iNOS mRNA. Among transcription factors known to be related to iNOS expression, activator protein (AP-1) activation was significantly blocked by FBP. FBP suppressed LPS-induced phosphorylation of three MAPK subtypes-p38 MAPK, JNK and ERK. FBP inhibited LPS-induced production of reactive oxygen species (ROS) and decreased intracellular GSSG/GSH ratio.


CONCLUSIONS
Our findings suggest that FBP attenuates the LPS-induced iNOS expression through inhibition of JNK and p38 MAPK, which might be related to ROS downregulation.
Department of Physiology, School of Medicine, Ajou University, Suwon, Republic of Korea.
Young-Chae
YC
Kim
Tae Yeop
TY
Park
Eunjoo
E
Baik
Soo Hwan
SH
Lee
D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D019610:Cytoprotection; D005635:Fructosediphosphates / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D048670:MAP Kinase Kinase 4 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D017628:Microglia / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010766:Phosphorylation; D012333:RNA, Messenger / Q000096:biosynthesis; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
D005635:Fructosediphosphates; D008070:Lipopolysaccharides; D018696:Neuroprotective Agents; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; C029063:fructose-1,6-diphosphate