Nitro-linoleic acid inhibits vascular smooth muscle cell proliferation via the Keap1/Nrf2 signaling pathway

Am J Physiol Heart Circ Physiol. 2007 Jul;293(1):H770-6. doi: 10.1152/ajpheart.00261.2007. Epub 2007 Apr 27.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Proliferation / drug effects*
  • Cells, Cultured
  • Cyclin-Dependent Kinase Inhibitor p27 / metabolism
  • Dose-Response Relationship, Drug
  • Intracellular Signaling Peptides and Proteins
  • Kelch-Like ECH-Associated Protein 1
  • Linoleic Acids / administration & dosage*
  • Male
  • Muscle, Smooth, Vascular / cytology
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / physiology*
  • Myocytes, Smooth Muscle / cytology
  • Myocytes, Smooth Muscle / drug effects
  • Myocytes, Smooth Muscle / physiology*
  • NF-E2-Related Factor 2 / metabolism*
  • Nitro Compounds / administration & dosage*
  • Proteins / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction / drug effects
  • Signal Transduction / physiology*

Substances

  • 10-nitro-9,12-octadecadienoic acid
  • Intracellular Signaling Peptides and Proteins
  • KEAP1 protein, rat
  • Kelch-Like ECH-Associated Protein 1
  • Linoleic Acids
  • NF-E2-Related Factor 2
  • Nitro Compounds
  • Proteins
  • Cyclin-Dependent Kinase Inhibitor p27