GSBS Student Publications

Title

Prolonged signaling at the parathyroid hormone receptor by peptide ligands targeted to a specific receptor conformation

UMMS Affiliation

Graduate School of Biomedical Sciences; Endocrine Unit and Center for Systems Biology

Date

10-24-2008

Document Type

Article

Medical Subject Headings

Animals; Bone and Bones; Guanosine 5'-O-(3-Thiotriphosphate); Humans; Kidney; Ligands; Mice; Peptides; Protein Binding; Protein Structure, Tertiary; Rats; Receptor, Parathyroid Hormone, Type 1; *Signal Transduction; Time Factors

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

The parathyroid hormone receptor (PTHR) is a class B G protein-coupled receptor that plays critical roles in bone and mineral ion metabolism. Ligand binding to the PTHR involves interactions to both the amino-terminal extracellular (N) domain, and transmembrane/extracellular loop, or juxtamembrane (J) regions of the receptor. Recently, we found that PTH(1-34), but not PTH-related protein, PTHrP(1-36), or M-PTH(1-14) (M = Ala/Aib(1),Aib(3),Gln(10),Har(11),Ala(12),Trp(14),Arg(19)), binds to the PTHR in a largely GTPgammaS-resistant fashion, suggesting selective binding to a novel, high-affinity conformation (R(0)), distinct from the GTPgammaS-sensitive conformation (RG). We examined the effects in vitro and in vivo of introducing the M substitutions, which enhance interaction to the J domain, into PTH analogs extended C-terminally to incorporate residues involved in the N domain interaction. As compared with PTH(1-34), M-PTH(1-28) and M-PTH(1-34) bound to R(0) with higher affinity, produced more sustained cAMP responses in cells, formed more stable complexes with the PTHR in FRET and subcellular localization assays, and induced more prolonged calcemic and phosphate responses in mice. Moreover, after 2 weeks of daily injection in mice, M-PTH(1-34) induced larger increases in trabecular bone volume and greater increases in cortical bone turnover, than did PTH(1-34). Thus, the putative R(0) PTHR conformation can form highly stable complexes with certain PTH ligand analogs and thereby mediate surprisingly prolonged signaling responses in bone and/or kidney PTH target cells. Controlling, via ligand analog design, the selectivity with which a PTH ligand binds to R(0), versus RG, may be a strategy for optimizing signaling duration time, and hence therapeutic efficacy, of PTHR agonist ligands.

Rights and Permissions

Citation: Proc Natl Acad Sci U S A. 2008 Oct 28;105(43):16525-30. Epub 2008 Oct 22. Link to article on publisher's site

DOI of Published Version

10.1073/pnas.0808750105

Related Resources

Link to Article in PubMed

Journal Title

Proceedings of the National Academy of Sciences of the United States of America

PubMed ID

18946036