Villacorta Luis, Zhang Jifeng, Garcia-Barrio Minerva T, Chen Xi-lin, Freeman Bruce A, Chen Yuqing E, Cui Taixing
Department of Internal Medicine, Cardiovascular Center, University of Michigan Medical Center, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA.
Am J Physiol Heart Circ Physiol. 2007 Jul;293(1):H770-6. doi: 10.1152/ajpheart.00261.2007. Epub 2007 Apr 27.
Nitroalkenes, the nitration products of unsaturated fatty acids formed via NO-dependent oxidative reactions, have been demonstrated to exert strong biological actions in endothelial cells and monocytes/macrophages; however, little is known about their effects on vascular smooth muscle cells (VSMCs). The present study examined the role of nitro-linoleic acid (LNO(2)) in the regulation of VSMC proliferation. We observed that LNO(2) inhibited VSMC proliferation in a dose-dependent manner. In addition, LNO(2) induced growth arrest of VSMCs in the G(1)/S phase of the cell cycle with an upregulation of the cyclin-dependent kinase inhibitor p27(kip1). Furthermore, LNO(2) triggered nuclear factor-erythroid 2-related factor 2 (Nrf2) nuclear translocation and activation of the antioxidant-responsive element-driven transcriptional activity via impairing Kelch-like ECH-associating protein 1 (Keap1)-mediated negative control of Nrf2 activity in VSMCs. LNO(2) upregulated the expression of Nrf2 protein levels, but not mRNA levels, in VSMCs. A forced activation of Nrf2 led to an upregulation of p27(kip1) and growth inhibition of VSMCs. In contrast, knock down of Nrf2 using an Nrf2 siRNA approach reversed the LNO(2)-induced upregulation of p27(kip1) and inhibition of cellular proliferation in VSMCs. These studies provide the first evidence that nitroalkene LNO(2) inhibits VSMC proliferation through activation of the Keap1/Nrf2 signaling pathway, suggesting an important role of nitroalkenes in vascular biology.
硝基烯烃是通过一氧化氮依赖的氧化反应形成的不饱和脂肪酸的硝化产物，已被证明在内皮细胞和单核细胞/巨噬细胞中发挥强大的生物学作用；然而，关于它们对血管平滑肌细胞（VSMC）的影响却知之甚少。本研究探讨了硝基油酸（LNO₂）在调节VSMC增殖中的作用。我们观察到LNO₂以剂量依赖的方式抑制VSMC增殖。此外，LNO₂诱导VSMC在细胞周期的G₁/S期生长停滞，并上调细胞周期蛋白依赖性激酶抑制剂p27（kip1）。此外，LNO₂通过损害VSMC中Kelch样ECH相关蛋白1（Keap1）介导的对Nrf2活性的负调控，触发核因子红细胞2相关因子2（Nrf2）的核转位并激活抗氧化反应元件驱动的转录活性。LNO₂上调了VSMC中Nrf2蛋白水平的表达，但未上调mRNA水平。Nrf2的强制激活导致p27（kip1）上调和VSMC生长抑制。相反，使用Nrf2 siRNA方法敲低Nrf2可逆转LNO₂诱导的VSMC中p27（kip1）上调和细胞增殖抑制。这些研究提供了首个证据，即硝基烯烃LNO₂通过激活Keap1/Nrf2信号通路抑制VSMC增殖，表明硝基烯烃在血管生物学中具有重要作用。
