Sugimoto Koichi, Ishibashi Toshiyuki, Sawamura Tatsuya, Inoue Nobutaka, Kamioka Masashi, Uekita Hironori, Ohkawara Hiroshi, Sakamoto Takayuki, Sakamoto Nobuo, Okamoto Yasuo, Takuwa Yoh, Kakino Akemi, Fujita Yoshiko, Tanaka Takeshi, Teramoto Tamio, Maruyama Yukio, Takeishi Yasuchika
First Department of Internal Medicine, Fukushima Medical University, 1 Hikarigaoka, Fukushima 960-1295, Japan.
Cardiovasc Res. 2009 Oct 1;84(1):127-36. doi: 10.1093/cvr/cvp177. Epub 2009 Jun 1.
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.
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.
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.
RhoA和Rac1激活在内皮功能障碍中起关键作用。凝集素样氧化低密度脂蛋白受体1（LOX-1）是内皮细胞（ECs）中氧化低密度脂蛋白（ox-LDL）的主要受体。膜型1基质金属蛋白酶（MT1-MMP）已被证明参与动脉粥样硬化的发生。本研究旨在探讨LOX-1-MT1-MMP轴在ECs中对ox-LDL应答时RhoA和Rac1激活中的作用。
ox-LDL在培养的人主动脉ECs中诱导RhoA和Rac1快速激活以及MT1-MMP活性。抑制LOX-1可阻止ox-LDL依赖的RhoA和Rac1激活。小干扰RNA敲低MT1-MMP可阻止ox-LDL诱导的RhoA和Rac1激活，表明MT1-MMP在RhoA和Rac1的上游。荧光免疫染色显示LOX-1和MT1-MMP共定位，免疫沉淀检测到LOX-1与MT1-MMP形成复合物。阻断LOX-1或MT1-MMP可阻止RhoA依赖的内皮型一氧化氮合酶蛋白下调和细胞侵袭、Rac1介导的NADPH氧化酶活性以及活性氧生成。
本研究提供证据表明，LOX-1-MT1-MMP轴在ox-LDL刺激下的RhoA和Rac1激活信号通路中起关键作用，提示该轴可能是治疗内皮功能障碍的一个有前景靶点。
