Different response patterns of several ligands at the sphingosine-1-phosphate receptor subtype 3 (S1P(3)).
OBJECTIVE
Recently, some ligands targeting the sphingosine-1-phosphate receptor subtype 3 (S1P(3)) have become available. The characterization of these compounds was mainly based on one functional read-out system, although S1P(3) receptors are known to activate different signal transduction pathways. Therefore, this study pharmacologically characterizes these compounds using different assays.


METHODS
Using CHO-FlpIn cells expressing the human S1P(3) receptor the potencies and maximal effects of S1P, FTY720-P, VPC23019, VPC23153 and VPC24191 were determined in three different assays [inhibition of cAMP accumulation, elevation of intracellular calcium concentrations ([Ca(2+)](i)) and S1P(3) receptor internalization].


RESULTS
All compounds tested inhibited forskolin-induced cAMP accumulation, increased [Ca(2+)](i) and induced S1P(3) receptor internalization but with different potencies and maximal effects. S1P was the most potent compound in all assays followed by FTY720-P. The VPC compounds were generally less potent than S1P and FTY720-P. Regarding the maximal effects, all compounds except VPC23153, behaved as full agonists in the cAMP accumulation assay. In the calcium assay, FTY720-P, VPC23019 and VPC24191 displayed partial and VPC23153 weak partial agonist activity, relative to S1P. Interestingly, treatment with the G(i) inactivator Pertussis toxin, did not affect S1P-induced [Ca(2+)](i) elevations but inhibited those in response to the other compounds, by about 50%.


CONCLUSIONS
This study demonstrated differential response patterns at the S1P(3) receptor for a range of ligands. These differences could indicate the presence of functional selectivity at this receptor as FTY720-P and the VPC compounds seemed to signal predominantly via G(i)- whereas S1P activated G(i) and G(q)-coupled pathways.
Jongsma
M
M
Department of Pharmacology & Pharmacotherapy, Academic Medical Center, Amsterdam, The Netherlands.
van Unen
J
J
van Loenen
P B
PB
Michel
M C
MC
Peters
S L M
SL
Alewijnse
A E
AE
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D020013:Calcium Signaling / Q000187:drug effects; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004705:Endocytosis / Q000187:drug effects; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008246:Lysophospholipids / Q000494:pharmacology; D010755:Organophosphates / Q000494:pharmacology; D037342:Pertussis Toxin / Q000494:pharmacology; D049349:Receptors, Lysosphingolipid / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology*; D013997:Time Factors; D014162:Transfection
D020536:Enzyme Activators; C525008:FTY 720P; D008024:Ligands; D008246:Lysophospholipids; D010755:Organophosphates; D049349:Receptors, Lysosphingolipid; D005576:Colforsin; C060506:sphingosine 1-phosphate; D000242:Cyclic AMP; D037342:Pertussis Toxin; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D000262:Adenylyl Cyclases; D013110:Sphingosine