Activation of calcitonin receptor and calcitonin receptor-like receptor by membrane-anchored ligands.
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.
Chang
Chia Lin
CL
Reproductive Biology and Stem Cell Research Program, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California 94305-5317, USA.
Park
Jae-Il
JI
Hsu
Sheau Yu Teddy
SY
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
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