Cys2,7EtalphaCGRP is a potent agonist for CGRP1 receptors in SK-N-MC cells.
The present study reveals that cystein2,7 ethyl-amidealphaCGRP (Cys2,7EtalphaCGRP), an advertised calcitonin gene-related peptide 2 (CGRP2) receptor subtype-selective agonist, is also a potent agonist for the calcitonin gene-related peptide 1 (CGRP1) receptors natively expressed in the SK-N-MC human neuroblastoma cell line. Cys2,7EtalphaCGRP and alpha calcitonin gene-related peptide (alphaCGRP) promote cyclic AMP accumulation in intact SK-N-MC cells to the same extent with EC50 of 1.6+/-0.2 and 0.4+/-0.08 nM, respectively. The antagonist alpha calcitonin gene-related peptide-8-37 (alphaCGRP-(8-37)) produces a concentration-dependent rightward shift of the alphaCGRP- and Cys2,7EtalphaCGRP concentration-response curves with KB-values (71+/-33 and 47+/-21 nM, respectively). The competitive antagonism by alphaCGRP-(8-37) and the similar KB-values suggests that alphaCGRP and Cys2,7EtalphaCGRP stimulate the same receptor. In competition binding studies with [125I]-alphaCGRP on SK-N-MC cell membranes, Cys2,7EtalphaCGRP and alphaCGRP-(8-37) display high affinity for the majority of the binding sites with Ki-values of 0.030+/-0.013 and 0.60+/-0.013 nM, respectively. The present findings are at odds with the proclaimed utilization of Cys2,7EtalphaCGRP as a CGRP2 receptor-selective pharmacological tool. Differences between the agonistic profile of this ligand in this and other experimental systems might be species--or even cell type--dependent.
Nodin
Christina
C
Preclinical Research & Development, AstraZeneca Mölndal, 43183 Mölndal, Sweden.
Vauquelin
Georges
G
von Mentzer
Bengt
B
D001665:Binding Sites; D001667:Binding, Competitive; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D000242:Cyclic AMP / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007457:Iodine Radioisotopes; D007700:Kinetics; D008024:Ligands; D009447:Neuroblastoma / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology*; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000819:agonists* / Q000378:metabolism
D007457:Iodine Radioisotopes; D008024:Ligands; D010446:Peptide Fragments; D018015:Receptors, Calcitonin Gene-Related Peptide; C058636:calcitonin gene-related peptide (8-37); D000242:Cyclic AMP; D015740:Calcitonin Gene-Related Peptide