title: Receptor activity modifying proteins (RAMPs) interact with the VPAC2 receptor and CRF1 receptors and modulate their function.
abstract: OBJECTIVE
  Although it is established that the receptor activity modifying proteins (RAMPs) can interact with a number of GPCRs, little is known about the consequences of these interactions. Here the interaction of RAMPs with the glucagon-like peptide 1 receptor (GLP-1 receptor), the human vasoactive intestinal polypeptide/pituitary AC-activating peptide 2 receptor (VPAC(2)) and the type 1 corticotrophin releasing factor receptor (CRF(1)) has been examined.
  
  
  METHODS
  GPCRs were co-transfected with RAMPs in HEK 293S and CHO-K1 cells. Cell surface expression of RAMPs and GPCRs was examined by ELISA. Where there was evidence for interactions, agonist-stimulated cAMP production, Ca(2+) mobilization and GTPγS binding to G(s), G(i), G(12) and G(q) were examined. The ability of CRF to stimulate adrenal corticotrophic hormone release in Ramp2(+/-) mice was assessed.
  
  
  RESULTS
  The GLP-1 receptor failed to enhance the cell surface expression of any RAMP. VPAC(2) enhanced the cell surface expression of all three RAMPs. CRF(1) enhanced the cell surface expression of RAMP2; the cell surface expression of CRF(1) was also increased. There was no effect on agonist-stimulated cAMP production. However, there was enhanced G-protein coupling in a receptor and agonist-dependent manner. The CRF(1) : RAMP2 complex resulted in enhanced elevation of intracellular calcium to CRF and urocortin 1 but not sauvagine. In Ramp2(+/-) mice, there was a loss of responsiveness to CRF.
  
  
  CONCLUSIONS
  The VPAC(2) and CRF(1) receptors interact with RAMPs. This modulates G-protein coupling in an agonist-specific manner. For CRF(1), coupling to RAMP2 may be of physiological significance.
authors.affiliation: School of Life and Health Sciences, Aston University, Birmingham, UK.
authors.forename: D
authors.initials: D
authors.lastname: Wootten
authors.forename: H
authors.initials: H
authors.lastname: Lindmark
authors.forename: M
authors.initials: M
authors.lastname: Kadmiel
authors.forename: H
authors.initials: H
authors.lastname: Willcockson
authors.forename: K M
authors.initials: KM
authors.lastname: Caron
authors.forename: J
authors.initials: J
authors.lastname: Barwell
authors.forename: T
authors.initials: T
authors.lastname: Drmota
authors.forename: D R
authors.initials: DR
authors.lastname: Poyner
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D011485:Protein Binding; D060888:Real-Time Polymerase Chain Reaction; D058263:Receptor Activity-Modifying Protein 2 / Q000235:genetics / Q000378:metabolism; D058261:Receptor Activity-Modifying Proteins / Q000378:metabolism*; D018019:Receptors, Corticotropin-Releasing Hormone / Q000378:metabolism*; D051239:Receptors, Vasoactive Intestinal Peptide, Type II / Q000378:metabolism*; D014162:Transfection; D000099052:CRF Receptor, Type 1
chemical_list: C545506:Ramp2 protein, mouse; D058263:Receptor Activity-Modifying Protein 2; D058261:Receptor Activity-Modifying Proteins; D018019:Receptors, Corticotropin-Releasing Hormone; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000099052:CRF Receptor, Type 1; D000324:Adrenocorticotropic Hormone; D000242:Cyclic AMP; D002118:Calcium