Pharmacological characterization of novel alpha-Calcitonin Gene-Related Peptide (CGRP) receptor peptide antagonists that are selective for human CGRP receptors.
Human alpha-calcitonin gene-related peptide (CGRP) is a 37-residue neuropeptide that produces a variety of cardiovascular and other effects via activation of specific CGRP receptors that produce cAMP. Functional CGRP receptors are a heterodimeric complex composed of the heptahelical calcitonin receptor-like receptor and the single transmembrane receptor activity-modifying protein 1. Based on the known structures of the antagonist CGRP((8-37)) and the human CGRP receptor, we designed novel CGRP receptor peptide antagonists with modifications to promote high affinity and selectivity for human CGRP receptors. Antagonist affinity (K(B)) at CGRP receptors was determined using the mouse thoracic aorta and human SK-N-MC cells. In aorta, CGRP((8-37)), [N-alpha-benzoyl]human alpha-CGRP((8-37)) [bzl-CGRP((8-37))], and [N-alpha-benzoyl-His(10)-benzyl]human alpha-CGRP((8-37)) [bzl-bn-CGRP((8-37))] caused rightward shifts in the concentration-response relaxation curve for CGRP with K(B) values of 1000, 88, and 50 nM, respectively. In human SK-N-MC cells, CGRP((8-37)), bzl-CGRP((8-37)), and bzl-bn-CGRP((8-37)) caused rightward shifts in the concentration-response curve for CGRP-stimulated cAMP production with K(B) values of 797, 15, and 0.63 nM, respectively. Thus, CGRP((8-37)) had the same affinity for human and mouse CGRP receptors, whereas bzl-CGRP((8-37)) and bzl-bn-CGRP((8-37)) displayed 6- and 80-fold higher affinities, respectively, for human CGRP receptors. In addition, the selectivity of the antagonists for human CGRP receptors was highly correlated with the antagonist hydrophobicity index. These relatively high-affinity, species-selective peptide antagonists provide novel tools to differentiate structural and functional features that are unique to the human CGRP receptor. Thus, these analogs may be useful compounds for development of drugs to treat migraine headache and other cardiovascular diseases.
Taylor
Christopher K
CK
Creighton University School of Medicine, Department of Pharmacology, 2500 California Plaza, Omaha, NE 68178, USA.
Smith
D David
DD
Hulce
Martin
M
Abel
Peter W
PW
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism* / Q000494:pharmacology; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D058286:Calcitonin Receptor-Like Protein; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry; D051379:Mice; D058261:Receptor Activity-Modifying Proteins; D018003:Receptors, Calcitonin / Q000737:chemistry; D013045:Species Specificity; D013329:Structure-Activity Relationship
C545578:CALCRL protein, human; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D058286:Calcitonin Receptor-Like Protein; C545579:Calcrl protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D058261:Receptor Activity-Modifying Proteins; D018003:Receptors, Calcitonin; D015740:Calcitonin Gene-Related Peptide