HDL induces NO-dependent vasorelaxation via the lysophospholipid receptor S1P3
Jerzy-Roch Nofer, … , Jerold Chun, Bodo Levkau
Jerzy-Roch Nofer, … , Jerold Chun, Bodo Levkau
Published February 15, 2004
Citation Information: J Clin Invest. 2004;113(4):569-581. https://doi.org/10.1172/JCI18004.
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Article Cardiology

HDL induces NO-dependent vasorelaxation via the lysophospholipid receptor S1P3

Abstract

HDL is a major atheroprotective factor, but the mechanisms underlying this effect are still obscure. HDL binding to scavenger receptor-BI has been shown to activate eNOS, although the responsible HDL entities and signaling pathways have remained enigmatic. Here we show that HDL stimulates NO release in human endothelial cells and induces vasodilation in isolated aortae via intracellular Ca2+ mobilization and Akt-mediated eNOS phosphorylation. The vasoactive effects of HDL could be mimicked by three lysophospholipids present in HDL: sphingosylphosphorylcholine (SPC), sphingosine-1-phosphate (S1P), and lysosulfatide (LSF). All three elevated intracellular Ca2+ concentration and activated Akt and eNOS, which resulted in NO release and vasodilation. Deficiency of the lysophospholipid receptor S1P3 (also known as LPB3 and EDG3) abolished the vasodilatory effects of SPC, S1P, and LSF and reduced the effect of HDL by approximately 60%. In endothelial cells from S1P3-deficient mice, Akt phosphorylation and Ca2+ increase in response to HDL and lysophospholipids were severely reduced. In vivo, intra-arterial administration of HDL or lysophospholipids lowered mean arterial blood pressure in rats. In conclusion, we identify HDL as a carrier of bioactive lysophospholipids that regulate vascular tone via S1P3-mediated NO release. This mechanism may contribute to the vasoactive effect of HDL and represent a novel aspect of its antiatherogenic function.

Authors

Jerzy-Roch Nofer, Markus van der Giet, Markus Tölle, Iza Wolinska, Karin von Wnuck Lipinski, Hideo A. Baba, Uwe J. Tietge, Axel Gödecke, Isao Ishii, Burkhard Kleuser, Michael Schäfers, Manfred Fobker, Walter Zidek, Gerd Assmann, Jerold Chun, Bodo Levkau

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HDL induces NO release and vasodilation via Akt-mediated eNOS phosphoryl...
HDL induces NO release and vasodilation via Akt-mediated eNOS phosphorylation in endothelial cells and in aortic segments. (a) Left panel: [32P]orthophosphate-labeled HUVECs were stimulated with HDL (0.5 mg/ml) in the presence or absence of LY294002 (10 μmol/l). Immunoprecipitated eNOS (ip) was analyzed by autoradiography (n = 3), and amounts of immunoprecipitated protein were detected by Western blotting. Phosphorylation of Akt at Ser473 was determined in cell lysates with a phosphospecific antibody (n = 5). Right panel: Time-dependence of HDL-induced eNOS and Akt phosphorylation at Ser1177 and Ser473, respectively, as analyzed by densitometry (n = 3). (b) Following precontraction of thoracic aortic rings from WKY rats with PE (1 × 10–6 mol/l, arrows), direct relaxation responses to HDL (0.5 mg/ml) in the absence or presence of LY294002 (10 μmol/l) were evaluated. Shown are original tracings from one experiment of eight. (c) Aortic segments perfused with 0.5 mg/ml HDL were fixed and immunostained for phospho-Ser1177-eNOS. Arrows indicate phospho-eNOS staining in the endothelial lining (original magnification, ×200). (d) Fura2-AM–loaded HUVECs were stimulated with 1 mg/ml HDL in the presence or absence of BAPTA-2AM (20 μmol/l) or Ni2+ (5 mM). [Ca2+]i was measured by fluorescence spectroscopy. Original tracings from representative experiments were superimposed for comparison. (e) HUVECs loaded with DAF-2DA and preincubated with BAPTA-2AM (20 μmol/l) or Ni2+ (5 mmol/l) were stimulated with HDL (1 mg/ml) and observed under a fluorescence microscope. Shown are representative results for one experiment of three.