Biochemical evidence for somatostatin receptors in murine neuroblastoma clone N1E-115.
Radioligand binding and functional assays were employed to demonstrate the existence of somatostatin receptors in the murine neuroblastoma clone N1E-115. Saturation experiments with [125I][Tyr11]somatostatin-14 indicated the presence of a single class of binding sites in membranes prepared from N1E-115 cells (Kd = 83 pM; Bmax = 21,000 receptors/cell). Somatostatin-14, somatostatin-28 and L363586 (cyclo(N-Me-ALA-TYR-D-TRP-LYS-VAL-PHE] all displaced the 125I-ligand monophasically in N1E-115 cells (Ki values were 28, 82 and 34 pM, respectively), which contrasted with the binding heterogeneity apparent with L363586 in rat brain membranes. The binding of [125I][Tyr11]somatostatin-14 was reduced by GppNHp, indicating that N1E-115 somatostatin receptors interacted with guanine nucleotide binding protein(s). Somatostatin agonists decreased by 30-50% the levels of [3H]cyclic AMP induced in intact cells by forskolin, prostaglandin E1, or vasoactive intestinal polypeptide. The EC50 values for inhibition of the [3H]cyclic AMP response to PGE1 by L363586, somatostatin-14, and somatostatin-28 were 0.24, 0.63 and 1.0 nM, respectively. Pertussis toxin treatment of N1E-115 cells reduced both binding to the receptor and the functional response to somatostatin-14. These data suggest that a single class of somatostatin receptors in N1E-115 cells are linked to the inhibition of adenylate cyclase through a Gi protein.
McKinney
M
M
Neuroscience Research Division, Abbott Laboratories, Abbott Park, IL 60064.
Barrett
R W
RW
D037361:Adenylate Cyclase Toxin; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002999:Clone Cells; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D007457:Iodine Radioisotopes; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism*; D037342:Pertussis Toxin; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D017481:Receptors, Somatostatin; D015290:Second Messenger Systems; D013004:Somatostatin / Q000031:analogs & derivatives / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D037361:Adenylate Cyclase Toxin; D007457:Iodine Radioisotopes; D017981:Receptors, Neurotransmitter; D017481:Receptors, Somatostatin; D010566:Virulence Factors, Bordetella; D013004:Somatostatin; D000242:Cyclic AMP; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D006152:Cyclic GMP