(Taken directly from the application) The diverse endocrine actions of PTH and paracrine actions of PTHrP are determined by the local concentrations of ligands and the responsiveness of target cells. Cellular responsiveness is determined by the number of receptors at the cell surface, the ability of receptors to convert ligand binding to G protein(s) activation, and the distal biological responses to G protein(s). This proposal will focus on understanding the post-translational events that regulate the responsiveness of the PTH/PTHrP receptor. We have powerful tools for probing the molecular mechanisms involved in each of these processes. These include specific receptor antibodies, green-fluorescent protein-tagged receptors, and libraries of mutant receptors (phosphorylation-deficient, constitutively-active, activation-deficient and Gq-deficient), PTH analogs (AC-selective) and stable bone-derived cell lines with different patterns of differentiation and activation of bone-specific genes in response to continuous versus intermittent PTH treatment.
In Aim I the phosphorylation sites will be mapped and the role of receptor phosphorylation and of G protein receptor kineses in internalization and desensitization will be determined.
In Aim II, mutant receptors, which dissociate binding from activation, will be used to determine if binding and/or activation is/are required for phosphorylation, internalization and/or desensitization.
In Aim III the green fluorescent protein-tagged PTH/PTHrP receptors will be used to characterize the cellular proteins that associate with the internalized PTH/PTHrP receptor vesicles and to examine the role of receptor phosphorylation in this process. The physiological relevance of internalization and desensitization will be examined in the bone-derived cell lines that have different patterns of biologic responses to continuous versus intermittent PTH treatment. We propose in Aim IV to interfere with the desensitization process in these cells and determine how this interference affects the osteoblast's responses to intermittent versus continuous administration of PTH.

Project Start
1999-04-15
Project End
1999-11-30
Budget Start
Budget End
Support Year
31
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
Dedic, Christopher; Hung, Tin Shing; Shipley, Alan M et al. (2018) Calcium fluxes at the bone/plasma interface: Acute effects of parathyroid hormone (PTH) and targeted deletion of PTH/PTH-related peptide (PTHrP) receptor in the osteocytes. Bone 116:135-143
Mizuhashi, Koji; Ono, Wanida; Matsushita, Yuki et al. (2018) Resting zone of the growth plate houses a unique class of skeletal stem cells. Nature 563:254-258
Hanna, Patrick; Grybek, Virginie; Perez de Nanclares, Guiomar et al. (2018) Genetic and Epigenetic Defects at the GNAS Locus Lead to Distinct Patterns of Skeletal Growth but Similar Early-Onset Obesity. J Bone Miner Res 33:1480-1488
Wein, Marc N; Foretz, Marc; Fisher, David E et al. (2018) Salt-Inducible Kinases: Physiology, Regulation by cAMP, and Therapeutic Potential. Trends Endocrinol Metab 29:723-735
Bastepe, Murat (2018) GNAS mutations and heterotopic ossification. Bone 109:80-85
Christov, Marta; Clark, Abbe R; Corbin, Braden et al. (2018) Inducible podocyte-specific deletion of CTCF drives progressive kidney disease and bone abnormalities. JCI Insight 3:
Roszko, Kelly L; Bi, Ruiye; Gorvin, Caroline M et al. (2017) Knockin mouse with mutant G?11 mimics human inherited hypocalcemia and is rescued by pharmacologic inhibitors. JCI Insight 2:e91079
Grigelioniene, Giedre; Nevalainen, Pasi I; Reyes, Monica et al. (2017) A Large Inversion Involving GNAS Exon A/B and All Exons Encoding Gs? Is Associated With Autosomal Dominant Pseudohypoparathyroidism Type Ib (PHP1B). J Bone Miner Res 32:776-783
Balani, Deepak H; Ono, Noriaki; Kronenberg, Henry M (2017) Parathyroid hormone regulates fates of murine osteoblast precursors in vivo. J Clin Invest 127:3327-3338
Cheloha, Ross W; Chen, Bingming; Kumar, Niyanta N et al. (2017) Development of Potent, Protease-Resistant Agonists of the Parathyroid Hormone Receptor with Broad ? Residue Distribution. J Med Chem 60:8816-8833

Showing the most recent 10 out of 215 publications