LOX-1-MT1-MMP axis is crucial for RhoA and Rac1 activation induced by oxidized low-density lipoprotein in endothelial cells.
OBJECTIVE
RhoA and Rac1 activation plays a key role in endothelial dysfunction. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a major receptor for oxidized low-density lipoprotein (ox-LDL) in endothelial cells (ECs). Membrane type 1 matrix metalloproteinase (MT1-MMP) has been shown to be involved in atherogenesis. This study was conducted to investigate the role of the LOX-1-MT1-MMP axis in RhoA and Rac1 activation in response to ox-LDL in ECs.


RESULTS
Ox-LDL induced rapid RhoA and Rac1 activation as well as MT1-MMP activity in cultured human aortic ECs. Inhibition of LOX-1 prevented ox-LDL-dependent RhoA and Rac1 activation. Knockdown of MT1-MMP by small interfering RNA prevented ox-LDL-induced RhoA and Rac1 activation, indicating that MT1-MMP is upstream of RhoA and Rac1. Fluorescent immunostaining revealed the colocalization of LOX-1 and MT1-MMP, and the formation of a complex of LOX-1 with MT1-MMP was detected by immunoprecipitation. Blockade of LOX-1 or MT1-MMP prevented RhoA-dependent endothelial NO synthase protein downregulation and cell invasion, Rac1-mediated NADPH oxidase activity, and reactive oxygen species generation.


CONCLUSIONS
The present study provides evidence that the LOX-1-MT1-MMP axis plays a crucial role in RhoA and Rac1 activation signalling pathways in ox-LDL stimulation, suggesting that this axis may be a promising target for treating endothelial dysfunction.
Sugimoto
Koichi
K
First Department of Internal Medicine, Fukushima Medical University, 1 Hikarigaoka, Fukushima 960-1295, Japan.
Ishibashi
Toshiyuki
T
Sawamura
Tatsuya
T
Inoue
Nobutaka
N
Kamioka
Masashi
M
Uekita
Hironori
H
Ohkawara
Hiroshi
H
Sakamoto
Takayuki
T
Sakamoto
Nobuo
N
Okamoto
Yasuo
Y
Takuwa
Yoh
Y
Kakino
Akemi
A
Fujita
Yoshiko
Y
Tanaka
Takeshi
T
Teramoto
Tamio
T
Maruyama
Yukio
Y
Takeishi
Yasuchika
Y
D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D008077:Lipoproteins, LDL / Q000633:toxicity*; D053511:Matrix Metalloproteinase 14 / Q000502:physiology*; D019255:NADPH Oxidases / Q000502:physiology; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D051127:Scavenger Receptors, Class E / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D020830:rac1 GTP-Binding Protein / Q000502:physiology*; D020742:rhoA GTP-Binding Protein / Q000502:physiology*
D008077:Lipoproteins, LDL; C495137:OLR1 protein, human; C107953:RAC1 protein, human; D017382:Reactive Oxygen Species; D051127:Scavenger Receptors, Class E; C099252:oxidized low density lipoprotein; C066737:RHOA protein, human; D052250:Nitric Oxide Synthase Type III; D019255:NADPH Oxidases; C507086:MMP14 protein, human; D053511:Matrix Metalloproteinase 14; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein