P2Y 2 receptor-mediated lymphotoxin-α secretion regulates intercellular cell adhesion molecule-1 expression in vascular smooth muscle cells

Cheikh I. Seye, Yuksel Agca, Cansu Agca, Wilbert Derbigny

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12 Scopus citations

Abstract

The proinflammatory cytokine lymphotoxin-α (LTA) is thought to contribute to the pathogenesis of atherosclerosis. However, the mechanisms that regulate its expression in vascular smooth muscle cells (VSMC) are poorly understood. The ability of exogenous nucleotides to stimulate LTA production was evaluated in VSMC by ELISA. The P2Y 2 nucleotide receptor (P2Y 2R) agonist UTP stimulates a strong and sustained release of LTA from WT but not P2Y 2R -/- SMC. Assessment of LTA gene transcription by LTA promoter-luciferase construct indicated that LTA levels are controlled at the level of transcription. We show using RNAi techniques that knockdown of the actin-binding protein filamin-A (FLNa) severely impaired nucleotide-induced Rho activation and consequent Rho-mediated LTA secretion. Reintroduction of FLNa in FLNa RNAi SMC rescued UTP-induced LTA expression. In addition, we found that UTP-stimulated LTA secretion is not sensitive to brefeldin A, which blocks the formation of vesicles involved in protein transport from the endoplasmic reticulum to the Golgi apparatus, suggesting that P2Y 2R/filamin-mediated secretion of LTA is independent of the endoplasmic reticulum/Golgi secretory vesicle route. Furthermore, UTP selectively induces ICAM-1 expression in WT but not SMC expressing a truncated P2Y 2R deficient in LTA secretion. These data suggest that P2Y 2R recruits FLNa to provide a cytoskeletal scaffold necessary for Rho signaling pathway upstream of LTA release and subsequent stimulation of ICAM-1 expression on vascular smooth muscle cells.

Original languageEnglish (US)
Pages (from-to)10535-10543
Number of pages9
JournalJournal of Biological Chemistry
Volume287
Issue number13
DOIs
StatePublished - Mar 23 2012

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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