Pharmacological Characterization of Novel α-Calcitonin Gene-Related Peptide (CGRP) Receptor Peptide Antagonists That Are Selective for Human CGRP Receptors
- Departments of Pharmacology (C.K.T., P.W.A.) and Biomedical Sciences (D.D.S.), School of Medicine and Department of Chemistry (M.H.), College of Arts and Sciences, Creighton University, Omaha, Nebraska
- Address correspondence to:
Dr. Peter W. Abel, Creighton University School of Medicine, Department of Pharmacology, 2500 California Plaza, Omaha, NE 68178. E-mail: pabel{at}creighton.edu
Abstract
Human α-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 (KB) at CGRP receptors was determined using the mouse thoracic aorta and human SK-N-MC cells. In aorta, CGRP(8–37), [N-α-benzoyl]human α-CGRP(8–37) [bzl-CGRP(8–37)], and [N-α-benzoyl-His10-benzyl]human α-CGRP(8–37) [bzl-bn-CGRP(8–37)] caused rightward shifts in the concentration-response relaxation curve for CGRP with KB 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 KB 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.
Footnotes
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This work was supported by an American Heart Association PreDoctoral Fellowship (to C.K.T.) and by National Institutes of Health Grant P20 RR16469.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.106.108316.
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ABBREVIATIONS: CGRP, α-calcitonin gene-related peptide; CL, calcitonin receptor-like receptor; RAMP1, receptor activity-modifying protein 1; CGRP(8–37), human α-calcitonin gene-related peptide(8–37); bzl-CGRP(8–37), [N-α-benzoyl]human α-CGRP(8–37); bzl-bn-CGRP(8–37), [N-α-benzoyl-His10-benzyl]human α-CGRP(8–37); Boc, N-α-tert-butyloxycarbonyl; RP-HPLC, reversed phase-high performance liquid chromatography; ESI-MS, electrospray-ionization mass spectrometry; BIBN4096BS, N-[1-[[6-amino-1-oxo-1-(4-pyridin-4-ylpiperazin-1-yl)hexan-2-yl]carbamoyl]-2-(3,5-dibromo-4-hydroxy-phenyl)ethyl]-4-(2-oxo-1,4-dihydroquinazolin-3-yl)piperidine-1-carboxamide; Compound 1, 4-(2-oxo-2,3-dihydro-benzoimidazol-1-yl)piperidine-1-carboxylic acid [1-(3,5-dibromo-4-hydroxy-benzyl)-2-oxo-2-(4-phenyl-piperazin-1-yl)-ethyl]-amide.
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- Received May 23, 2006.
- Accepted July 19, 2006.
- The American Society for Pharmacology and Experimental Therapeutics
