Leukotriene-C4 synthase, a critical enzyme in the activation of store-independent Orai1/Orai3 channels, is required for neointimal hyperplasia

J Biol Chem. 2015 Feb 20;290(8):5015-5027. doi: 10.1074/jbc.M114.625822. Epub 2014 Dec 24.


Leukotriene-C4 synthase (LTC4S) generates LTC4 from arachidonic acid metabolism. LTC4 is a proinflammatory factor that acts on plasma membrane cysteinyl leukotriene receptors. Recently, however, we showed that LTC4 was also a cytosolic second messenger that activated store-independent LTC4-regulated Ca(2+) (LRC) channels encoded by Orai1/Orai3 heteromultimers in vascular smooth muscle cells (VSMCs). We showed that Orai3 and LRC currents were up-regulated in medial and neointimal VSMCs after vascular injury and that Orai3 knockdown inhibited LRC currents and neointimal hyperplasia. However, the role of LTC4S in neointima formation remains unknown. Here we show that LTC4S knockdown inhibited LRC currents in VSMCs. We performed in vivo experiments where rat left carotid arteries were injured using balloon angioplasty to cause neointimal hyperplasia. Neointima formation was associated with up-regulation of LTC4S protein expression in VSMCs. Inhibition of LTC4S expression in injured carotids by lentiviral particles encoding shRNA inhibited neointima formation and inward and outward vessel remodeling. LRC current activation did not cause nuclear factor for activated T cells (NFAT) nuclear translocation in VSMCs. Surprisingly, knockdown of either LTC4S or Orai3 yielded more robust and sustained Akt1 and Akt2 phosphorylation on Ser-473/Ser-474 upon serum stimulation. LTC4S and Orai3 knockdown inhibited VSMC migration in vitro with no effect on proliferation. Akt activity was suppressed in neointimal and medial VSMCs from injured vessels at 2 weeks postinjury but was restored when the up-regulation of either LTC4S or Orai3 was prevented by shRNA. We conclude that LTC4S and Orai3 altered Akt signaling to promote VSMC migration and neointima formation.

Keywords: Calcium Channel; Calcium Release-activated Calcium Channel Protein 1 (ORAI1); Calcium Transport; Cardiovascular Disease; LTC4; Orai1; Orai3; Vascular Smooth Muscle Cells.

Publication types

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

MeSH terms

  • Animals
  • Calcium Channels / genetics
  • Calcium Channels / metabolism*
  • Gene Expression Regulation, Enzymologic / genetics
  • Glutathione Transferase / biosynthesis*
  • Glutathione Transferase / genetics
  • Hyperplasia / genetics
  • Hyperplasia / metabolism
  • Hyperplasia / pathology
  • Male
  • Muscle, Smooth, Vascular / metabolism*
  • Muscle, Smooth, Vascular / pathology
  • Myocytes, Smooth Muscle / metabolism*
  • Myocytes, Smooth Muscle / pathology
  • NFATC Transcription Factors / genetics
  • NFATC Transcription Factors / metabolism
  • Neointima / genetics
  • Neointima / metabolism*
  • Neointima / pathology
  • ORAI1 Protein
  • Phosphorylation / genetics
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction / genetics


  • Calcium Channels
  • NFATC Transcription Factors
  • ORAI1 Protein
  • Orai1 protein, rat
  • Orai3 protein, rat
  • Glutathione Transferase
  • Akt1 protein, rat
  • Akt2 protein, rat
  • Proto-Oncogene Proteins c-akt
  • leukotriene-C4 synthase