RT Journal Article
SR Electronic
T1 Determinants of 1-Piperidinecarboxamide, <em>N</em>-[2-[[5-Amino-<em>l</em>-[[4-(4-pyridinyl)-<em>l</em>-piperazinyl]carbonyl]pentyl]amino]-1-[(3,5-dibromo-4-hydroxyphenyl)methyl]-2-oxoethyl]-4-(1,4-dihydro-2-oxo-3(2<em>H</em>)-quinazolinyl) (BIBN4096BS) Affinity for Calcitonin Gene-Related Peptide and Amylin Receptors—The Role of Receptor Activity Modifying Protein 1
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 1984
OP 1991
DO 10.1124/mol.106.027953
VO 70
IS 6
A1 Debbie L. Hay
A1 George Christopoulos
A1 Arthur Christopoulos
A1 Patrick M. Sexton
YR 2006
UL http://molpharm.aspetjournals.org/content/70/6/1984.abstract
AB 1-Piperidinecarboxamide, N-[2-[[5-amino-l-[[4-(4-pyridinyl)-l-piperazinyl]carbonyl]pentyl]amino]-1-[(3,5-dibromo-4-hydroxyphenyl)methyl]-2-oxoethyl]-4-(1,4-dihydro-2-oxo-3(2H)-quinazolinyl) (BIBN4096BS), a calcitonin gene-related peptide (CGRP) receptor antagonist, can alleviate the symptoms of migraine and is highly selective for CGRP over adrenomedullin (AM) receptors. These receptors are heterodimers of the calcitonin receptor-like receptor (CL) and receptor activity modifying proteins (RAMPs), with the pharmacological properties determined by the RAMP subunit. BIBN4096BS-sensitive CGRP1 receptors are CL/RAMP1, whereas BIBN4096BS-insensitive AM receptors are CL/RAMP2 or CL/RAMP3 (AM1 and AM2, respectively), implicating RAMP1 in conferring BIB-N4096BS sensitivity. Because calcitonin receptors [CT(a)] also interact with RAMP1 [AMY1(a) receptors], BIBN4096BS could also have affinity for these receptors. To test this, receptors were transfected into COS-7 cells and agonist-stimulated cAMP levels measured in the presence and absence of antagonists. We found that AMY1(a) receptors were ∼150-fold less sensitive to BIBN4096BS antagonism than CGRP1 receptors. In contrast, AMY3(a) [CT(a)/RAMP3] or AM2 receptors were not sensitive to BIBN4096BS antagonism. We investigated Trp74 in RAMP1, a residue implicated in the species selectivity of BIBN4096BS. BIBN4096BS affinity was reduced at AMY1(a) and CGRP1 receptors when this residue was mutated to lysine or alanine. The equivalent residue in RAMP3, Glu74, when mutated to tryptophan (E74W), induced BIBN4096BS sensitivity at AM2 and AMY3(a) receptors. It is interesting that a selective reduction in AM potency was observed at E74W AM2 receptors, implicating this residue in AM interactions with this receptor. These data support the importance of Trp74 in RAMP1 in the interaction of BIBN4096BS with CGRP1 and AMY1(a) receptors and identified Glu74 in RAMP3 as the first amino acid in RAMP important for agonist interactions with calcitonin-family receptors. The American Society for Pharmacology and Experimental Therapeutics