Direct interactions between calcitonin-like receptor (CLR) and CGRP-receptor component protein (RCP) regulate CGRP receptor signaling.
Calcitonin gene-related peptide (CGRP) is a neuropeptide with multiple neuroendocrine roles, including vasodilation, migraine, and pain. The receptor for CGRP is a G protein-coupled receptor (GPCR) that requires three proteins for function. CGRP binds to a heterodimer composed of the GPCR calcitonin-like receptor (CLR) and receptor activity-modifying protein (RAMP1), a single transmembrane protein required for pharmacological specificity and trafficking of the CLR/RAMP1 complex to the cell surface. In addition, the CLR/RAMP1 complex requires a third protein named CGRP-receptor component protein (RCP) for signaling. Previous studies have demonstrated that depletion of RCP from cells inhibits CLR signaling, and in vivo studies have demonstrated that expression of RCP correlates with CLR signaling and CGRP efficacy. It is not known whether RCP interacts directly with CLR to exert its effect. The current studies identified a direct interaction between RCP and an intracellular domain of CLR using yeast two-hybrid analysis and coimmunoprecipitation. When this interacting domain of CLR was expressed as a soluble fusion protein, it coimmunoprecipitated with RCP and inhibited signaling from endogenous CLR. Expression of this dominant-negative domain of CLR did not significantly inhibit trafficking of CLR to the cell surface, and thus RCP may not have a chaperone function for CLR. Instead, RCP may regulate CLR signaling in the cell membrane, and direct interaction between RCP and CLR is required for CLR activation. To date, RCP has been found to interact only with CLR and represents a novel neuroendocrine regulatory step in GPCR signaling.
Department of Physiology and Biophysics, University of Miami School of Medicine, Miami, Florida 33101, USA.
Sophie C
SC
Egea
Ian M
IM
Dickerson
D000818:Animals; D058286:Calcitonin Receptor-Like Protein / Q000502:physiology*; D002478:Cells, Cultured; D049452:Green Fluorescent Proteins; D051379:Mice; D023421:Models, Animal; D041681:NIH 3T3 Cells; D017434:Protein Structure, Tertiary / Q000502:physiology; D058262:Receptor Activity-Modifying Protein 1 / Q000502:physiology; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000502:physiology*; D011993:Recombinant Fusion Proteins; D015398:Signal Transduction / Q000502:physiology*
D058286:Calcitonin Receptor-Like Protein; C545579:Calcrl protein, mouse; C491563:Crcp protein, mouse; C545505:Ramp1 protein, mouse; D058262:Receptor Activity-Modifying Protein 1; D018015:Receptors, Calcitonin Gene-Related Peptide; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins