Functional serotonin-2B receptors are expressed by a teratocarcinoma-derived cell line during serotoninergic differentiation.
Among immortalized teratocarcinoma-derived cells, the clone 1C11 is a committed precursor of the neuronal lineage. On day 2 of its serotoninergic differentiation, this clone expresses only one subtype of serotonin [5-hydroxytryptamine (5-HT)] receptor, which is functionally coupled to phosphatidylinositol hydrolysis. The identity of these receptors was established by comparing their properties with those of 5-HT2B receptors expressed by LMTK- fibroblasts stably transfected with the recently cloned murine cDNA NP75 (LM5 cells). In both cell types, the analysis of (+/-)-1-(2,5-dimethoxy-4-[125I]iodophenyl)- 2-aminopropane HCl ([125I]DOI) binding revealed the presence of a single class of sites, the affinity of which was 1 order of magnitude lower than that reported for 5-HT2A receptors. In 1C11 cells differentiated for 2 days, as well as in LM5 cells, DOI binding was decreased by nonhydrolyzable analogs of GTP, indicating that the 5-HT2B receptor is functionally coupled to a G protein. The DOI-induced increase of phosphoinositide hydrolysis, which was correlated with both GTPase activity and binding data, is mediated by a Gq protein. This work demonstrates that the 5-HT2B receptor is functionally expressed before complete serotoninergic differentiation of 1C11 cells. The inducible 1C11 clone thus provides an in vitro model to investigate the possible role of the 5-HT2B receptor in the expression of the serotoninergic phenotype.
Loric
S
S
Laboratoire de Différenciation Cellulaire, Institut Pasteur, Paris, France.
Maroteaux
L
L
Kellermann
O
O
Launay
J M
JM
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D018076:DNA, Complementary / Q000235:genetics; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D020558:GTP Phosphohydrolases / Q000187:drug effects / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology; D006868:Hydrolysis; D051379:Mice; D010716:Phosphatidylinositols / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011985:Receptors, Serotonin / Q000378:metabolism / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013268:Stimulation, Chemical; D018243:Teratocarcinoma / Q000473:pathology / Q000648:ultrastructure*; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000648:ultrastructure*
D018076:DNA, Complementary; D010716:Phosphatidylinositols; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D012701:Serotonin; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins