Histamine upregulates gene expression of endothelial nitric oxide synthase in human vascular endothelial cells.
BACKGROUND
Histamine has a short-term, transient, stimulating effect on endothelial nitric oxide synthase (eNOS) activity; however, long-term effects on eNOS have not been described yet. In addition, the vascular effect of histamine seems to depend critically on eNOS functionality. Therefore, we studied the effects of histamine on eNOS gene expression and function.


RESULTS
In human umbilical vein endothelial cells (HUVECs) and HUVEC-derived EA.hy 926 cells, histamine upregulated eNOS mRNA (RNase protection assay) and protein (electron microscopic immunocytochemistry) expression. The upregulation of eNOS could be prevented by mepyramine, a selective antagonist at the H1 receptor, but not by H2 and H3 receptor antagonists. Incubation of EA.hy 926 cells with histamine led to the activation of calcium/calmodulin-dependent protein kinase II (CaMK II; in vitro phosphorylation assay). The histamine-induced eNOS expression was completely prevented by KN-93, an inhibitor of CaMK II. Histamine increased the activity of a 1.6-kb human eNOS promoter fragment (luciferase reporter gene assay), an effect that was also blocked by mepyramine. Under normal conditions, eNOS upregulation by histamine resulted in increased nitric oxide production (measured by nitric oxide chemiluminescence and RFL-6 reporter cell assay). Under conditions of oxidative stress, however, the eNOS upregulated by histamine produced reactive oxygen species (CM-H2DCFDA oxidation-based fluorescence assay).


CONCLUSIONS
Stimulation of the H1 receptor increases eNOS transcription in endothelial cells by a signaling pathway involving CaMK II. This eNOS upregulation may be protective under normal conditions, but it may become harmful under conditions of oxidative stress when eNOS produces reactive oxygen species at the expense of nitric oxide.
Li
Huige
H
Department of Pharmacology, Johannes Gutenberg University, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany.
Burkhardt
Christian
C
Heinrich
Ulf-Rüdiger
UR
Brausch
Isolde
I
Xia
Ning
N
Förstermann
Ulrich
U
D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics*; D052250:Nitric Oxide Synthase Type III; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger / Q000096:biosynthesis; D017382:Reactive Oxygen Species / Q000378:metabolism; D011969:Receptors, Histamine H1 / Q000502:physiology; D015533:Transcriptional Activation; D015854:Up-Regulation
D004791:Enzyme Inhibitors; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D011969:Receptors, Histamine H1; D009569:Nitric Oxide; D006632:Histamine; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases