Change of endothelin receptor subtype in the MEG-01 human megakaryoblastic cell line.
The aim of this investigation was to determine whether the endothelin receptor subtype of a megakaryoblastic cell line (MEG-01) changes during culture passages as cells undergo maturation and differentiation. On early-passage cells, binding of [125I]endothelin-1 was completely inhibited by 1 microM BQ 123 (cyclo-[D-tryptophanyl-D-aspartyl-prolyl-D-valyl-leucyl]), but not by sarafotoxin 6C. Also the endothelin-1-enhancing effect on [Ca2+]i was prevented by BQ 123, whereas sarafotoxin 6C had no effect on [Ca2+]i. In late-passage cells, endothelin ET(B) analogs, unlike endothelin ET(A) analogs, competed with binding of [125I]endothelin-1. Endothelin ET(B) receptor agonists increased [Ca2+]i while the endothelin-1-induced response was inhibited by BQ 788 ([N-[(2R,6S)-2,6-dimethyl-piperidinocarbonyl]-4-methyl-D-leucyl]-[ N(omega)-(methoxycarbonyl)-D-tryptophanyl]-D-norleucine), but not by BQ 123, although both endothelin ET(A) and ET(B) receptor mRNAs were expressed, as shown by reverse transcriptase-polymerase chain reaction. These results demonstrate that in MEG-01 cells switch from expression of endothelin ET(A) to expression of ET(B) receptors during culture. The data also suggest that late-passage MEG-01 cells look like platelets, in terms of endothelin receptor subtype.
Hamroun
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INSERM U. 469, Montpellier, France.
Mathieu
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MN
Chevillard
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C
D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D016232:Endothelins / Q000494:pharmacology; D006801:Humans; D008533:Megakaryocytes / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D017466:Receptors, Endothelin / Q000187:drug effects / Q000378:metabolism*; D014757:Viper Venoms / Q000494:pharmacology
D016232:Endothelins; D009842:Oligopeptides; D010446:Peptide Fragments; D010880:Piperidines; D017466:Receptors, Endothelin; D014757:Viper Venoms; C057354:sarafotoxins s6; C074308:sovateltide; C086539:BQ 788; D002118:Calcium