High glucose-induced oxidative stress increases transient receptor potential channel expression in human monocytes.
OBJECTIVE
Transient receptor potential (TRP) channel-induced cation influx activates human monocytes, which play an important role in the pathogenesis of atherosclerosis. In the present study, we investigated the effects of high glucose-induced oxidative stress on TRP channel expression in human monocytes.


METHODS
Human monocytes were exposed to control conditions (5.6 mmol/l d-glucose), high glucose (30 mmol/l d-glucose or l-glucose), 100 micromol/l peroxynitrite, or high glucose in the presence of the superoxide dismutase mimetic tempol (100 micromol/l). TRP mRNA and TRP protein expression was measured using quantitative real-time RT-PCR and quantitative in-cell Western assay, respectively. Calcium influx and intracellular reactive oxygen species were measured using fluorescent dyes.


RESULTS
Administration of high d-glucose significantly increased reactive oxygen species. High d-glucose or peroxynitrite significantly increased the expression of TRP canonical type 1 (TRPC1), TRPC3, TRPC5, TRPC6, TRP melastatin type 6 (TRPM6), and TRPM7 mRNA and TRPC3 and TRPC6 proteins. High d-glucose plus tempol or high l-glucose did not affect TRP expression. Increased oxidative stress by lipopolysaccharide or tumor necrosis factor-alpha increased TRP mRNA expression, whereas the reduction of superoxide radicals using diphenylene iodonium significantly reduced TRP mRNA expression. Increased TRPC3 and TRPC6 protein expression was accompanied by increased 1-oleoyl-2-acetyl-sn-glycerol-induced calcium influx, which was blocked by the TRPC inhibitor 2-aminoethoxydiphenylborane. TRPC6 mRNA was significantly higher in monocytes from 18 patients with type 2 diabetes compared with 28 control subjects (P < 0.05).


CONCLUSIONS
High d-glucose-induced oxidative stress increases TRP expression and calcium influx in human monocytes, pointing to a novel pathway for increased activation of monocytes and hence atherosclerosis in patients with diabetes.
Wuensch
Tilo
T
Charité Campus Benjamin Franklin, Med. Klinik Nephrologie, Berlin, Germany.
Thilo
Florian
F
Krueger
Katharina
K
Scholze
Alexandra
A
Ristow
Michael
M
Tepel
Martin
M
D017931:DNA Primers; D005786:Gene Expression Regulation / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D009000:Monocytes / Q000187:drug effects / Q000502:physiology*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D030421:Peroxynitrous Acid / Q000494:pharmacology; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics*; D012194:RNA-Directed DNA Polymerase; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050052:TRPC Cation Channels / Q000235:genetics*; D000074287:TRPC6 Cation Channel
D017931:DNA Primers; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D050052:TRPC Cation Channels; C104603:TRPC3 cation channel; C491780:TRPC5 protein, human; D000074287:TRPC6 Cation Channel; C117032:TRPC6 protein, human; C096351:transient receptor potential cation channel, subfamily C, member 1; D030421:Peroxynitrous Acid; D012313:RNA; D012194:RNA-Directed DNA Polymerase; D005947:Glucose