Differential coupling of the sphingosine 1-phosphate receptors Edg-1, Edg-3, and H218/Edg-5 to the G(i), G(q), and G(12) families of heterotrimeric G proteins.
Sphingosine 1-phosphate (S1P) is one of several bioactive phospholipids that exert profound mitogenic and morphogenic actions. Originally characterized as a second messenger, S1P is now recognized to achieve many of its effects through cell surface, G protein-coupled receptors. We used a subunit-selective [(35)S]GTPgammaS binding assay to investigate whether the variety of actions exerted through Edg-1, a recently identified receptor for S1P, might be achieved through multiple G proteins. We found, employing both Sf9 and HEK293 cells, that Edg-1 activates only members of the G(i) family, and not G(s), G(q), G(12), or G(13). We additionally established that Edg-1 activates G(i) in response not only to S1P but also sphingosylphosphorylcholine; no effects of lysophosphatidic acid through Edg-1 were evident. Our assays further revealed a receptor(s) for S1P endogenous to HEK293 cells that mediates activation of G(13) as well as G(i). Because several of the biological actions of S1P are assumed to proceed through the G(12/13) family, we tested whether Edg-3 and H218/Edg-5, two other receptors for S1P, might have a broader coupling profile than Edg-1. Indeed, Edg-3 and H218/Edg-5 communicate not only with G(i) but also with G(q) and G(13). These studies represent the first characterization of S1P receptor activity through G proteins directly and establish fundamental differences in coupling.
Windh
R T
RT
Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Lee
M J
MJ
Hla
T
T
An
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Barr
A J
AJ
Manning
D R
DR
D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D020672:I-kappa B Proteins; D017874:Immediate-Early Proteins / Q000378:metabolism*; D007700:Kinetics; D008246:Lysophospholipids; D046911:Macromolecular Substances; D000072000:NF-KappaB Inhibitor alpha; D011956:Receptors, Cell Surface / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D049312:Receptors, Lysophospholipid; D011994:Recombinant Proteins / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism; D018411:Spodoptera; D013462:Sulfur Radioisotopes; D014162:Transfection; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D017874:Immediate-Early Proteins; D008246:Lysophospholipids; D046911:Macromolecular Substances; C000606204:NFKBIA protein, human; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D049312:Receptors, Lysophospholipid; D011994:Recombinant Proteins; D013462:Sulfur Radioisotopes; D010566:Virulence Factors, Bordetella; D000072000:NF-KappaB Inhibitor alpha; C060506:sphingosine 1-phosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019204:GTP-Binding Proteins; D013110:Sphingosine