Activation of protease calpain by oxidized and glycated LDL increases the degradation of endothelial nitric oxide synthase.
Oxidation and glycation of low-density lipoprotein (LDL) promote vascular injury in diabetes; however, the mechanisms underlying this effect remain poorly defined. The present study was conducted to determine the effects of 'heavily oxidized' glycated LDL (HOG-LDL) on endothelial nitric oxide synthase (eNOS) function. Exposure of bovine aortic endothelial cells with HOG-LDL reduced eNOS protein levels in a concentration- and time-dependent manner, without altering eNOS mRNA levels. Reduced eNOS protein levels were accompanied by an increase in intracellular Ca(2+), augmented production of reactive oxygen species (ROS) and induction of Ca(2+)-dependent calpain activity. Neither eNOS reduction nor any of these other effects were observed in cells exposed to native LDL. Reduction of intracellular Ca(2+) levels abolished eNOS reduction by HOG-LDL, as did pharmacological or genetic through calcium channel blockers or calcium chelator BAPTA or inhibition of NAD(P)H oxidase (with apocynin) or inhibition of calpain (calpain 1-specific siRNA). Consistent with these results, HOG-LDL impaired acetylcholine-induced endothelium-dependent vasorelaxation of isolated mouse aortas, and pharmacological inhibition of calpain prevented this effect. HOG-LDL may impair endothelial function by inducing calpain-mediated eNOS degradation in a ROS- and Ca(2+)-dependent manner.
Dong
Yunzhou
Y
Harold Hamm Oklahoma Diabetes Center, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
Wu
Yong
Y
Wu
Mingyuan
M
Wang
Shuangxi
S
Zhang
Junhua
J
Xie
Zhonglin
Z
Xu
Jian
J
Song
Ping
P
Wilson
Kenneth
K
Zhao
Zhengxing
Z
Lyons
Timothy
T
Zou
Ming-Hui
MH
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002154:Calpain / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002417:Cattle; D003593:Cytoplasm / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D017127:Glycation End Products, Advanced; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D019255:NADPH Oxidases / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D021381:Protein Transport / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D000093844:Glycated Proteins
D002118:Calcium; D002154:Calpain; D017127:Glycation End Products, Advanced; D008077:Lipoproteins, LDL; D019255:NADPH Oxidases; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D011480:Protease Inhibitors; D046988:Proteasome Endopeptidase Complex; D017382:Reactive Oxygen Species; C031797:glycated lipoproteins, LDL; D000093844:Glycated Proteins; C099252:oxidized low density lipoprotein; C060505:neutrophil cytosolic factor 1