title: Localization of calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1) in human gastrointestinal tract.
abstract: Calcitonin gene-related peptide (CGRP) exerts its diverse effects on vasodilation, nociception, secretion, and motor function through a heterodimeric receptor comprising of calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1). Despite the importance of CLR·RAMP1 in human disease, little is known about its distribution in the human gastrointestinal (GI) tract, where it participates in inflammation and pain. In this study, we determined that CLR and RAMP1 mRNAs are expressed in normal human stomach, ileum and colon by RT-PCR. We next characterized antibodies that we generated to rat CLR and RAMP1 in transfected HEK cells. Having characterized these antibodies in vitro, we then localized CLR-, RAMP1-, CGRP- and intermedin-immunoreactivity (IMD-IR) in various human GI segments. In the stomach, nerve bundles in the myenteric plexus and nerve fibers throughout the circular and longitudinal muscle had prominent CLR-IR. In the proximal colon and ileum, CLR was found in nerve varicosities of the myenteric plexus and surrounding submucosal neurons. Interestingly, CGRP expressing fibers did not co-localize, but were in close proximity to CLR. However, CLR and RAMP1, the two subunits of a functional CGRP receptor were clearly localized in myenteric plexus, where they may form functional cell-surface receptors. IMD, another member of calcitonin peptide family was also found in close proximity to CLR, and like CGRP, did not co-localize with either CLR or RAMP1 receptors. Thus, CGRP and IMD appear to be released locally, where they can mediate their effect on their receptors regulating diverse functions such as inflammation, pain and motility.
authors.affiliation: Department of Surgery, Center for Neurobiology of Digestive Diseases, University of California San Francisco, San Francisco, CA 94143-0660, United States.
authors.forename: Graeme S
authors.initials: GS
authors.lastname: Cottrell
authors.forename: Farzad
authors.initials: F
authors.lastname: Alemi
authors.forename: Jacob G
authors.initials: JG
authors.lastname: Kirkland
authors.forename: Eileen F
authors.initials: EF
authors.lastname: Grady
authors.forename: Carlos U
authors.initials: CU
authors.lastname: Corvera
authors.forename: Aditi
authors.initials: A
authors.lastname: Bhargava
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000276:immunology / Q000378:metabolism; D058286:Calcitonin Receptor-Like Protein / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002460:Cell Line; D003106:Colon / Q000294:innervation / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005753:Gastric Mucosa / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007082:Ileum / Q000294:innervation / Q000378:metabolism*; D007249:Inflammation / Q000378:metabolism; D009197:Myenteric Plexus / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D036361:Peptide Hormones / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D058262:Receptor Activity-Modifying Protein 1 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D013270:Stomach / Q000294:innervation; D014162:Transfection
chemical_list: C484330:ADM2 protein, human; C545578:CALCRL protein, human; D058286:Calcitonin Receptor-Like Protein; D036361:Peptide Hormones; C545502:RAMP1 protein, human; D012333:RNA, Messenger; D058262:Receptor Activity-Modifying Protein 1; D015740:Calcitonin Gene-Related Peptide