Concomitant regulation of Ca2+ mobilization and G13 expression in human erythroleukemia cells.
In human erythroleukemia (HEL) cells, stimulation of alpha2-adrenoceptors by adrenaline or neuropeptide Y Y1 receptors by neuropeptide Y, concomitantly inhibit cAMP accumulation and stimulate mobilization of Ca2+ from intracellular stores via pertussis toxin-sensitive G-proteins. Treatment of HEL cells in chemically-defined, serum-free medium with 1.25% dimethylsulfoxide (DMSO) for 4 days, increased alpha2-adrenoceptor number by 120%, while the neuropeptide Y receptor number was not significantly changed. In DMSO-treated HEL cells, Ca2+ elevations by adrenaline or neuropeptide Y were significantly reduced by 28% and 57%, respectively, while basal Ca2+ and elevations by thrombin or thapsigargin were not significantly altered. Adrenaline and neuropeptide Y-induced inhibition of forskolin-stimulated cAMP accumulation was not significantly altered upon DMSO treatment. While immunodetectable alpha-subunits of Gi2 were not significantly changed by DMSO treatment, those of Gi3 were reduced by 27%. Inactivation of pertussis toxin substrates by pertussis toxin treatment and inhibition of adrenaline or neuropeptide Y stimulated Ca2+ elevations were linearly correlated. These data are compatible with the idea that, in HEL cells, alpha2-adrenoceptors and neuropeptide Y receptors couple to inhibition of adenylyl cyclase via Gi2 while they couple to Ca2+ elevations via Gi3.
Michel
M C
MC
Dept. of Medicine, University of Essen, Germany. martin.michel@uni-essen.de
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D037361:Adenylate Cyclase Toxin; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000096:biosynthesis*; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism*; D037342:Pertussis Toxin; D011869:Radioligand Assay; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D017476:Receptors, Neuropeptide Y / Q000378:metabolism; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D037361:Adenylate Cyclase Toxin; D018341:Receptors, Adrenergic, alpha-2; D011956:Receptors, Cell Surface; D017476:Receptors, Neuropeptide Y; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D000242:Cyclic AMP; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D002118:Calcium