Pharmacological and kinetic characterization of adrenomedullin 1 and calcitonin gene-related peptide 1 receptor reporter cell lines.
Adrenomedullin (ADM) and calcitonin gene-related peptide (CGRP) receptors and their respective ligands play important roles in cardiovascular (patho-)physiology. Functional expression of ADM and CGRP receptors requires the presence of the calcitonin receptor-like receptor (CRLR) together with receptor-activity-modifying proteins (RAMPs). We have characterized the expression patterns of CRLR and RAMP1 to RAMP3 in human cardiovascular-related tissues by quantitative polymerase chain reaction. We could identify high expression levels of CRLR, RAMP1, and RAMP2 in human heart and various blood vessels. RAMP3 expression in these tissues, however, was detectable at significantly lower levels. In addition, we describe here a novel, aequorin luminescence-based G protein-coupled receptor reporter assay that enables the real-time detection of receptor activation in living cells. In the assay system, intracellular cAMP levels are monitored with high sensitivity by using a modified, heteromultimeric cyclic nucleotide-gated channel mediating calcium influx. G(q)-coupled receptor activation is detected via aequorin luminescence stimulated by calcium release from intracellular stores. Using this novel reporter assay, we established and characterized stable ADM1 and CGRP1 receptor cell lines. The peptide ligands ADM, CGRP1, and CGRP2 were characterized as potent agonists at their respective receptors. In contrast, intermedin acted as a weak agonist on both receptors and showed only partial agonism on the ADM1 receptor. Agonist activities were effectively antagonized by the receptor antagonists ADM(22-52) and CGRP(8-37). Various vasoactive ADM fragments were also characterized but showed no activity on the ADM1 receptor cell line. In addition, luminescence signal kinetics after activation of G(s)- and G(q)-coupled receptors were found to be markedly different.
Wunder
Frank
F
Bayer HealthCare AG, Lead Discovery Wuppertal, Pharma Research Center, Aprather Weg 18a, D-42096 Wuppertal, Germany. frank.wunder@bayerhealthcare.com
Rebmann
Annegret
A
Geerts
Andreas
A
Kalthof
Bernd
B
D053607:Adrenomedullin / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001808:Blood Vessels / Q000378:metabolism; D016466:CHO Cells; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D058286:Calcitonin Receptor-Like Protein; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000096:biosynthesis; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000378:metabolism; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D007700:Kinetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D036361:Peptide Hormones; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D058262:Receptor Activity-Modifying Protein 1; D058263:Receptor Activity-Modifying Protein 2; D058264:Receptor Activity-Modifying Protein 3; D058261:Receptor Activity-Modifying Proteins; D018003:Receptors, Calcitonin / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000378:metabolism*
C507862:ADM protein, human; C484330:ADM2 protein, human; C545578:CALCRL protein, human; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D058286:Calcitonin Receptor-Like Protein; D054815:Cyclic Nucleotide-Gated Cation Channels; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D036361:Peptide Hormones; C545502:RAMP1 protein, human; C545503:RAMP2 protein, human; C545504:RAMP3 protein, human; D012333:RNA, Messenger; D058262:Receptor Activity-Modifying Protein 1; D058263:Receptor Activity-Modifying Protein 2; D058264:Receptor Activity-Modifying Protein 3; D058261:Receptor Activity-Modifying Proteins; D018003:Receptors, Calcitonin; D018015:Receptors, Calcitonin Gene-Related Peptide; D053607:Adrenomedullin; D000242:Cyclic AMP