Parathyroid hormone (PTH) is a vital regulator of serum calcium and phosphate levels and one of the few bone-active agents shown to be anabolic in humans, important for osteoporosis therapy. During the past granting period we have developed a high-resolution model for the binding of PTH to its G protein coupled receptor, PTH1R, employing a combination of photoaffinity labeling experiments (providing direct contact points between ligand and receptor) and NMR-based structural studies. In this renewal application, we propose to characterize the bimolecular interactions of PTH1R with the cytosolic signaling (e.g., G proteins) and non-signaling (e.g., NHERF, GRKs) proteins central for the biological actions of PTH.
We aim to characterize the determinant structural features of PTH1R for coupling to the G proteins, Gs, Gq/11, and Gi/o, responsible for the signaling properties associated with PTH. We have initiated NMR-based experiments, providing the structure and topological orientation of the cytoplasmic domains of PTH1R while associated with the G proteins. The molecular scaffolding protein, NHERF (Na+/H+ exchange regulatory factor) plays an important role the pharmacological profile of PTH1R, including signaling and receptor life-time (e.g., internalization and desensitization). Here, employing high-resolution NMR methods we will determine the structural features of the bimolecular interaction of NHERF (NHERF1 and NHERF2) with the C-termini of PTH1R and phospholipase C(beta) and use these results to rationally design potent inhibitors of the receptor-protein association. A molecular inhibitor of NHERF-PTH1R inteaction would be a useful physiological tool for detailing the role of this receptor/protein association and could eventually find use as a therapeutic regulator of PTH activity, affording control of the adenylyl cyclase and PLC signaling pathways associated with PTH1R.
A final aim i s to develop a soluble mimetic of PTH1R, using a 4-helix bundle as templates for the incorporation of the domains of PTH1 required for ligand binding (extracellular face of the receptor) and signaling properties (cytoplasmic face of the receptor). The soluble PTH1R template will allow for biophysical and structural studies as well as high-throughput screening of compound libraries.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM054082-15
Application #
7809478
Study Section
Skeletal Biology Development and Disease Study Section (SBDD)
Program Officer
Chin, Jean
Project Start
1996-05-01
Project End
2012-03-31
Budget Start
2010-04-01
Budget End
2012-03-31
Support Year
15
Fiscal Year
2010
Total Cost
$346,788
Indirect Cost
Name
Dartmouth College
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
041027822
City
Hanover
State
NH
Country
United States
Zip Code
03755
Bucur, Octavian; Gaidos, Gabriel; Yatawara, Achani et al. (2015) A novel caspase 8 selective small molecule potentiates TRAIL-induced cell death. Sci Rep 5:9893
Yatawara, Achani; Wilson, Jamie L; Taylor, Linda et al. (2013) C-terminus of ETA/ETB receptors regulate endothelin-1 signal transmission. J Pept Sci 19:257-62
Audu, Christopher O; Cochran, Jared C; Pellegrini, Maria et al. (2013) Recombinant production of TEV cleaved human parathyroid hormone. J Pept Sci 19:504-10
Yatawara, Achani K; Hodoscek, Milan; Mierke, Dale F (2013) Ligand binding site identification by higher dimension molecular dynamics. J Chem Inf Model 53:674-80
Pennarun, B; Gaidos, G; Bucur, O et al. (2013) killerFLIP: a novel lytic peptide specifically inducing cancer cell death. Cell Death Dis 4:e894
Wang, Wenjing; Nossoni, Zahra; Berbasova, Tetyana et al. (2012) Tuning the electronic absorption of protein-embedded all-trans-retinal. Science 338:1340-3
Thomas, Beena E; Sharma, Sandhya; Mierke, Dale F et al. (2009) PTH and PTH antagonist induce different conformational changes in the PTHR1 receptor. J Bone Miner Res 24:925-34
Seck, Thomas; Pellegrini, Maria; Florea, Ana Maria et al. (2005) The delta e13 isoform of the calcitonin receptor forms a six-transmembrane domain receptor with dominant-negative effects on receptor surface expression and signaling. Mol Endocrinol 19:2132-44