Coupling of ETB endothelin receptor to mitogen-activated protein kinase stimulation and DNA synthesis in primary cultures of rat astrocytes.
Astrocytes have been shown to express endothelin (ET) receptors functionally coupled, via different heterotrimeric G proteins, to several intracellular pathways. To assess the relative contribution of each subtype in the astrocytic responses to ET-1, effects of BQ123, an antagonist selective for the ET receptor subtype A (ETA-R), and IRL1620, an agonist selective for the ET receptor subtype B (ETB-R), were investigated in primary cultures of rat astrocytes. Binding experiments indicated that the ETB-R is the predominant subtype in these cells. Inhibition of forskolin-stimulated cyclic AMP production was observed under. ETB-R stimulation. Bordetella pertussis toxin (PTX) pretreatment completely abolished this effect, indicating that this pathway is coupled to the ETB-R via Gi protein. Increases of tyrosine phosphorylation of cellular proteins, stimulation of mitogen-activated protein kinase (MAPK), and DNA synthesis were also found to be mediated by the ETB-R, but through PTX-insensitive G protein. IRL1620-induced MAPK activation involved the adapter proteins Shc and Grb2 and the serine/threonine kinase Raf-1. This study reveals that the various effects of ET-1 in astrocytes are mediated by the ETB-R, which couples to multiple signaling pathways including the MAPK cascade.
Lazarini
F
F
Institut Cochin de Génétique Moléculaire, CNRS UPR 0415, Université Paris VII, Paris, France.
Strosberg
A D
AD
Couraud
P O
PO
Cazaubon
S M
SM
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000494:pharmacology*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000037:antagonists & inhibitors; D004247:DNA / Q000096:biosynthesis*; D004586:Electrophoresis; D065128:Endothelin Receptor Antagonists; D016232:Endothelins / Q000494:pharmacology; D051380:GRB2 Adaptor Protein; D019204:GTP-Binding Proteins / Q000502:physiology; D019950:Mitogen-Activated Protein Kinase 1; D010446:Peptide Fragments / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D037342:Pertussis Toxin; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf; D051381:Rats; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D048868:Adaptor Proteins, Signal Transducing; D065128:Endothelin Receptor Antagonists; D016232:Endothelins; D051380:GRB2 Adaptor Protein; C495950:Grb2 protein, rat; D010446:Peptide Fragments; D010456:Peptides, Cyclic; D011506:Proteins; D011518:Proto-Oncogene Proteins; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D010566:Virulence Factors, Bordetella; C074308:sovateltide; D014443:Tyrosine; D004247:DNA; D000242:Cyclic AMP; D037342:Pertussis Toxin; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D019204:GTP-Binding Proteins; C072247:cyclo(Trp-Asp-Pro-Val-Leu)