The human calcitonin receptor (CTR) is a G protein-coupled receptor that is an important drug target because of its role in mediating the distinct biological actions of two related endocrine peptide hormones, calcitonin (CT) and amylin (AMY). CT regulates calcium homeostasis and bone turnover by signaling through the CTR. AMY regulates blood glucose levels by signaling through a heterodimeric complex ofthe CTR and any one of three related receptor activity modifying proteins (RAMPs) that act as co-receptors to alter CTR specificity for AMY. Agonism of the CT and AMY receptors by synthetic analogs of the hormones is used to treat osteoporosis and types I and II diabetes, respectively. Despite the clinical value of CT and AMY receptor agonism, the molecular mechanisms of CTR hormone binding and RAMP-mediated alteration of CTR hormone specificity are poorly understood because of a lack of structural information for the hormone-receptor complexes. CT and AMY binding affinity and specificity are in large part determined by the extracellular domains (ECDs) ofthe CTR and RAMP integral membrane proteins. The goals of this proposal are to characterize the hormone-receptor ECD interactions and to determine crystal structures of soluble CT- and AMY-receptor ECD complexes. The results will define the molecular bases for CT and AMY binding to their receptor ECDs, delineate how RAMPs alter hormone specificity ofthe CTR, and provide structural templates to guide the design of optimized therapeutics targeting the receptors. We propose the following three aims: (1) Determine the molecular mechanism of CT recognition by the human CTR ECD. The crystal structures generated in this aim will define how human and salmon CT hormones bind to the CTR and aid the development of therapeutics for treating osteoporosis. (2) Determine the structural and functional bases for interaction ofthe CTR and RAMP ECDs. The resulting CTR ECD-RAMP ECD heterodimer structure will reveal the molecular architecture of an AMY receptor. (3) Determine the molecular mechanism of AMY binding to a CTR ECD-RAMP ECD heterodimer. Achieving this aim will define how a RAMP alters the hormone specificity of the CTR and aid the design of therapeutics for diabetes.

Public Health Relevance

The goal of this proposal is to determine the molecular mechanisms by which the hormones calcitonin and amylin are recognized by their cell surface G protein-coupled receptors. Analogs of calcitonin and amylin are used to treat osteoporosis and types I and II diabetes, respectively. Obtaining a detailed biochemical description of how these hormones bind to their receptors will facilitate the rational development of potent and selective next-generation therapeutic agents for the treatment of osteoporosis and diabetes.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Exploratory Grants (P20)
Project #
1P20GM103640-01
Application #
8465587
Study Section
Special Emphasis Panel (ZRR1-RI-B (01))
Project Start
Project End
Budget Start
2012-08-01
Budget End
2013-05-31
Support Year
1
Fiscal Year
2012
Total Cost
$254,810
Indirect Cost
$12,500
Name
University of Oklahoma Norman
Department
Type
DUNS #
848348348
City
Norman
State
OK
Country
United States
Zip Code
73019
Mooers, Blaine H M (2016) Simplifying and enhancing the use of PyMOL with horizontal scripts. Protein Sci 25:1873-82
Cruz-Reyes, Jorge; Mooers, Blaine H M; Abu-Adas, Zakaria et al. (2016) DEAH-RHA helicase•Znf cofactor systems in kinetoplastid RNA editing and evolutionarily distant RNA processes. RNA Dis 3:
Isom, Catherine E; Menon, Smita K; Thomas, Leonard M et al. (2016) Crystal structure and DNA binding activity of a PadR family transcription regulator from hypervirulent Clostridium difficile R20291. BMC Microbiol 16:231
Lavey, Nathan P; Coker, Jesse A; Ruben, Eliza A et al. (2016) Sclerotiamide: The First Non-Peptide-Based Natural Product Activator of Bacterial Caseinolytic Protease P. J Nat Prod 79:1193-7
Vazquez Reyes, Carolina; Tangprasertchai, Narin S; Yogesha, S D et al. (2016) Nucleic Acid-Dependent Conformational Changes in CRISPR-Cas9 Revealed by Site-Directed Spin Labeling. Cell Biochem Biophys :
Wang, Bing; Powell, Samantha M; Hessami, Neda et al. (2016) Crystal structures of two nitroreductases from hypervirulent Clostridium difficile and functionally related interactions with the antibiotic metronidazole. Nitric Oxide 60:32-39
Mooers, Blaine H M (2016) Direct-methods structure determination of a trypanosome RNA-editing substrate fragment with translational pseudosymmetry. Acta Crystallogr D Struct Biol 72:477-87
Wang, Bing; Thomas, Leonard M; Richter-Addo, George B (2016) Organometallic myoglobins: Formation of Fe-carbon bonds and distal pocket effects on aryl ligand conformations. J Inorg Biochem 164:1-4
Kumar, Vikas; Madina, Bhaskara R; Gulati, Shelly et al. (2016) REH2C Helicase and GRBC Subcomplexes May Base Pair through mRNA and Small Guide RNA in Kinetoplastid Editosomes. J Biol Chem 291:5753-64
Madina, Bhaskara R; Kumar, Vikas; Mooers, Blaine H M et al. (2015) Native Variants of the MRB1 Complex Exhibit Specialized Functions in Kinetoplastid RNA Editing. PLoS One 10:e0123441

Showing the most recent 10 out of 31 publications