Parathyroid hormone (PTH), acting through the PTH receptor (PTHR1), expressed in bone and kidney, plays a vital role in maintaining proper blood levels of calcium and phosphate, and also contributes to the regulation of bone growth and remodeling. PTHrP, acting through the same PTHR1, regulates the development of the skeleton and other tissues. Drugs that target the PTHR1 are of interest because they could potentially be used to treat human diseases, such as osteoporosis and hypoparathyroidism (HPT). Yet PTH(1-34) is the only FDA-approved PTH-based therapy. It is thus used to treat osteoporosis, and, while effective, must be injected once a day. The proposed studies will define the molecular mechanisms by which PTH ligands bind to and activate the PTHR1. They will generate new types of PTH analogs, including signaling selective analogs and novel long-acting ligands that are structurally more stable or have adducts that impair renal clearance, and will assess these analogs for binding to the PTHR1 in vitro, and for actions in animals. Also explored will be new non-peptidic, small-molecule ligands for the PTHR1. Selected ligands will be evaluated in a mouse model of HPT (PTH-null mice) for their capacity to normalize blood calcium. New long-acting PTH analogs will also be tested for their capacities to stimulate bone formation and improve strength when injected into mice at low-frequency intervals, such as once-weekly, and in a dual-therapy mode with the bone-resorption inhibitor, OPG-FC.

Public Health Relevance

The proposed studies will lead to a better understanding of how PTH ligands bind to and activate the PTHR1. They will also provide clues for. how to develop and utilize new PTH ligand analogs for more effective treatment of diseases such as osteoporosis and hypoparathyroidism.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Program Projects (P01)
Project #
2P01DK011794-46
Application #
8659672
Study Section
Special Emphasis Panel (ZDK1-GRB-J (O1))
Project Start
Project End
Budget Start
2013-12-01
Budget End
2014-11-30
Support Year
46
Fiscal Year
2014
Total Cost
$449,108
Indirect Cost
$187,932
Name
Massachusetts General Hospital
Department
Type
DUNS #
073130411
City
Boston
State
MA
Country
United States
Zip Code
02199
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