title: Activation of calcitonin receptor and calcitonin receptor-like receptor by membrane-anchored ligands.
abstract: G protein-coupled receptors (GPCRs) are the most important pharmaceutical targets, and more than 40% of drugs in use today modulate GPCR signaling. A major hurdle in the development of therapies targeting GPCRs is the drug candidate's nonselective actions in multiple tissues. The ability to spatially control GPCR signaling would provide a venue for developing therapies that require targeted GPCR signaling. Here, we show that the fusion of a RAMP1 co-receptor with the calcitonin gene-related peptide (CGRP), or calcitonin, transforms the RAMP1 from a co-receptor to bona fide membrane-anchored ligands (CGRP-RAMP1 and CAL-RAMP1). The CAL-RAMP1 selectively activates the calcitonin receptor (CR), whereas, the CGRP-RAMP1 activates both the calcitonin receptor-like receptor (CLR) and CR. Unlike a free peptide, which moves freely in the extracellular space and differentiates targets based on molecular affinity, the anchored CGRP-RAMP1 and CAL-RAMP1 ligands confine their activities to individual cells. In addition, our study showed that a CGRP8-37-RAMP1 chimera, but not RAMP1, functions as an antagonist for CGRP-RAMP1-mediated signaling, suggesting that the activation of CLR by CGRP-RAMP1 shares similar molecular mechanisms with the CGRP-mediated activation of CLR/RAMP1 receptor complexes. Taken together, our finding thus provides a novel class of ligands that activate CR and CLR exclusively in an autocrine manner and a proof-of-concept demonstration for future development of targeted therapies aimed at these receptors in specific cell populations.
authors.affiliation: Reproductive Biology and Stem Cell Research Program, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California 94305-5317, USA.
authors.forename: Chia Lin
authors.initials: CL
authors.lastname: Chang
authors.forename: Jae-Il
authors.initials: JI
authors.lastname: Park
authors.forename: Sheau Yu Teddy
authors.initials: SY
authors.lastname: Hsu
mesh_terms: D002116:Calcitonin / Q000235:genetics / Q000378:metabolism; D015740:Calcitonin Gene-Related Peptide / Q000235:genetics / Q000378:metabolism; D058286:Calcitonin Receptor-Like Protein; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D058262:Receptor Activity-Modifying Protein 1; D058261:Receptor Activity-Modifying Proteins; D018003:Receptors, Calcitonin / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: C545578:CALCRL protein, human; D058286:Calcitonin Receptor-Like Protein; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C545502:RAMP1 protein, human; D058262:Receptor Activity-Modifying Protein 1; D058261:Receptor Activity-Modifying Proteins; D018003:Receptors, Calcitonin; D011993:Recombinant Fusion Proteins; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide