Superoxide generated by lysophosphatidylcholine induces endothelial nitric oxide synthase downregulation in human endothelial cells.
We examined the mechanism through which lysophosphatidylcholine (LPC) induces endothelial nitric oxide (eNOS) downregulation. Human umbilical vein endothelial cells (HUVECs) were treated with LPC (50-150 microM) for 0.5-2 h or the reactive oxygen species (ROS) donors, xanthine/xanthine oxidase (X/XO), 1,4-hydroquinone (HQ) or tert-butylhydroperoxide (TBHP) for 2 h. Protein levels of eNOS, superoxide dismutase1 (SOD1), catalase, and phospho-extracellular signal regulated kinase 1/2 (pERK 1/2) were assessed using immunoblotting. LPC treatment reduced SOD1 levels but increased catalase levels. The superoxide donors X/XO and HQ showed similar effects. The hydroperoxide donor TBHP increased SOD1 levels but did not change catalase levels. LPC concentration- and time-dependently decreased eNOS levels, but this effect was blocked by antioxidants and SOD and potentiated by the SOD1 inhibitor, ammonium tetrathiomolybdate. LPC and X/XO inhibited ERK1/2 phosphorylation, whereas TBHP stimulated phosphorylation. Taken together, these data indicate that LPC induces superoxide overload in HUVECs via SOD1 inhibition and downregulates phospho-ERK1/2 and eNOS levels.
Choi
Shinkyu
S
Department of Physiology and Medical Research Center, School of Medicine, Ewha Womans University, Seoul, Republic of Korea.
Park
Seonghee
S
Liang
Guo Hua
GH
Kim
Ji Aee
JA
Suh
Suk Hyo
SH
D000975:Antioxidants / Q000494:pharmacology; D002374:Catalase / Q000378:metabolism; D015536:Down-Regulation; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology; D008244:Lysophosphatidylcholines / Q000494:pharmacology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D008982:Molybdenum / Q000494:pharmacology; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010766:Phosphorylation; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
D000975:Antioxidants; D004791:Enzyme Inhibitors; D006873:Hydroquinones; D008244:Lysophosphatidylcholines; D013481:Superoxides; D008982:Molybdenum; C020809:tetrathiomolybdate; D020122:tert-Butylhydroperoxide; D002374:Catalase; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D013482:Superoxide Dismutase; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C031927:hydroquinone