Stimulation of intracellular sphingosine-1-phosphate production by G-protein-coupled sphingosine-1-phosphate receptors.
Recently, a family of G-protein-coupled receptors named endothelial differentiation gene (Edg) receptor family has been identified, which are specifically activated by the two serum lipids, sphingosine-1-phosphate and lysophosphatidic acid. Sphingosine-1-phosphate can also act intracellularly to release Ca2+ from intracellular stores. Since in several cell types, G-protein-coupled lysophosphatidic acid or sphingosine-1-phosphate receptors mobilize Ca2+ in the absence of a measurable phospholipase C stimulation, it was analysed here whether intracellular sphingosine-1-phosphate production was the signalling mechanism used by extracellular sphingosine-1-phosphate for mobilization of stored Ca2+. Sphingosine-1-phosphate and the low affinity sphingosine-1-phosphate receptor agonist, sphingosylphosphorylcholine, induced a rapid, transient and nearly complete pertussis toxin-sensitive Ca2+ mobilization in human embryonic kidney (HEK-293) cells. The G-protein-coupled sphingosine-1-phosphate receptors, Edg-1, Edg-3 and Edg-5, were found to be endogenously expressed in these cells. Most interestingly, sphingosine-1-phosphate and sphingosylphosphorylcholine did not induce a measurable production of inositol-1,4,5-trisphosphate or accumulation of inositol phosphates. Instead, sphingosine-1-phosphate and sphingosylphosphorylcholine induced a rapid and transient increase in production of intracellular sphingosine-1-phosphate with a maximum of about 1.4-fold at 30 s. Stimulation of sphingosine-1-phosphate formation by sphingosine-1-phosphate and sphingosylphosphorylcholine was fully blocked by pertussis toxin, indicating that extracellular sphingosine-1-phosphate via endogenously expressed G(i)-coupled receptors induces a stimulation of intracellular sphingosine-1-phosphate production. As sphingosine-1-phosphate- and sphingosylphosphorylcholine-induced increases in intracellular Ca2+ were blunted by sphingosine kinase inhibitors, this sphingosine-1-phosphate production appears to mediate Ca2+ signalling by extracellular sphingosine-1-phosphate and sphingosylphosphorylcholine in HEK-293 cells.
Institut für Pharmakologie, Universitätsklinikum Essen, Hufelandstrasse 55, D-45122 Essen, Germany. meyer-heringdorf@uni-essen.de
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Meyer zu Heringdorf
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Lass
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Kuchar
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Lipinski
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Alemany
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Rümenapp
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Jakobs
D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D002460:Cell Line; D018679:Cholinergic Agonists / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D020672:I-kappa B Proteins; D017874:Immediate-Early Proteins / Q000378:metabolism*; D008246:Lysophospholipids; D000072000:NF-KappaB Inhibitor alpha; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000494:pharmacology; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000187:drug effects / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D049312:Receptors, Lysophospholipid; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D010738:Type C Phospholipases / Q000187:drug effects / Q000378:metabolism; D000099157:Sphingosine Kinase
D002217:Carbachol; D018679:Cholinergic Agonists; D004268:DNA-Binding Proteins; D019204:GTP-Binding Proteins; D020672:I-kappa B Proteins; D017874:Immediate-Early Proteins; D008246:Lysophospholipids; D000072000:NF-KappaB Inhibitor alpha; D010767:Phosphorylcholine; D017853:Phosphotransferases (Alcohol Group Acceptor); D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D049312:Receptors, Lysophospholipid; D013110:Sphingosine; D010738:Type C Phospholipases; D000099157:Sphingosine Kinase; C000606204:NFKBIA protein, human; C005356:sphingosine phosphorylcholine; C060506:sphingosine 1-phosphate