Peptide ligand binding properties of the corticotropin-releasing factor (CRF) type 2 receptor: pharmacology of endogenously expressed receptors, G-protein-coupling sensitivity and determinants of CRF2 receptor selectivity.
The CRF2 receptor is involved in stress responses, cardiovascular function and gastric motility. Endogenous agonists (urocortin (UCN) 2, UCN 3) and synthetic antagonists (astressin2-B, antisauvagine-30) are selective for CRF2 over the CRF1 receptor. Peptide ligand binding properties of the CRF2 receptor require further investigation, including ligand affinity for endogenously expressed receptors, the effect of receptor-G-protein coupling on ligand affinity, and the molecular basis of ligand selectivity. Ligand affinity for rat CRF(2a) in olfactory bulb and CRF(2b) in A7r5 cells was similar to that for the cloned human CRF(2a) receptor (within three-fold), except for oCRF (9.4- and 5.4-fold higher affinity in olfactory bulb and A7r5 cells, respectively). Receptor-G-protein uncoupling reduced agonist affinity only 1.2- to 6.5-fold (compared with 92-1300-fold for the CRF1 receptor). Ligand selectivity mechanisms were investigated using chimeric CRF2/CRF1 receptors. The juxtamembrane receptor domain determined selectivity of antisauvagine-30, the N-terminal-extracellular domain contributed to selectivity of UCN 3, and both domains contributed to selectivity of UCN 2 and astressin2-B. Therefore ligands differ in the contribution of receptor domains to their selectivity, and CRF2-selective antagonists bind the juxtamembrane domain. These findings will be important for identifying the CRF2 receptor in tissues and for developing ligands targeting the receptor, both of which will be useful in identifying the emerging physiological functions of the CRF2 receptor.
Hoare
Sam R J
SR
Department of Pharmacology, Neurocrine Biosciences Inc., 12790 El Camino Real, San Diego, CA 92130, USA. shoare@neurocrine.com
Sullivan
Susan K
SK
Fan
Jun
J
Khongsaly
Khamkeo
K
Grigoriadis
Dimitri E
DE
D029845:Amphibian Proteins; D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D003346:Corticotropin-Releasing Hormone / Q000737:chemistry / Q000494:pharmacology; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D006801:Humans; D020128:Inhibitory Concentration 50; D008024:Ligands; D009830:Olfactory Bulb / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology; D036361:Peptide Hormones; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011869:Radioligand Assay; D051381:Rats; D018019:Receptors, Corticotropin-Releasing Hormone / Q000737:chemistry* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D054832:Urocortins; D000099052:CRF Receptor, Type 1
D029845:Amphibian Proteins; C101531:CRF receptor type 2; D008024:Ligands; D010446:Peptide Fragments; D036361:Peptide Hormones; D010455:Peptides; D018019:Receptors, Corticotropin-Releasing Hormone; D011993:Recombinant Fusion Proteins; D054832:Urocortins; C116607:antisauvagine 30; C120841:astressin B; D000099052:CRF Receptor, Type 1; C025727:sauvagine; D003346:Corticotropin-Releasing Hormone; D000242:Cyclic AMP