Molecular insights into differentiated ligand recognition of the human parathyroid hormone receptor 2

The parathyroid hormone receptor 2 (PTH2R) is a class B1 G protein-coupled receptor (GPCR) involved in regulation of calcium transport, nociception mediation, and wound healing. Naturally occurring mutations in PTH2R were reported to cause hereditary diseases, including syndromic short stature. Here we report the cryo-electron microscopy structure of PTH2R bound to its endogenous ligand, tuberoinfundibular peptide (TIP39), and a heterotrimeric Gs protein at a global resolution of 2.8 Å. The structure reveals that TIP39 adopts a unique loop conformation at N terminus and deeply inserts into the orthosteric ligand-binding pocket in the transmembrane (TM) domain. Molecular dynamics (MD) simulation and site-directed mutagenesis studies uncover the basis of ligand specificity relative to three PTH2R agonists, TIP39, PTH, and PTH-related peptide (PTHrP). We also compare the action of TIP39 with an antagonist lacking six residues from the peptide N terminus, TIP(7-39), which underscores the indispensable role of the N terminus of TIP39 in PTH2R activation. Additionally, we unveil that a disease-associated mutation G258D significantly diminished cAMP accumulation induced by TIP39. Together, these results not only provide structural insights into ligand specificity and receptor activation of class B1 GPCRs, but also offer a foundation to systematically rationalize the available pharmacological data to develop novel therapies for various disorders associated with PTH2R.

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Molecular insights into differentiated ligand recognition of the human parathyroid hormone receptor 2

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2101279118 ◽

2021 ◽

Vol 118 (32) ◽

pp. e2101279118

Author(s):

Xi Wang ◽

Xi Cheng ◽

Lihua Zhao ◽

Yuzhe Wang ◽

Chenyu Ye ◽

...

Keyword(s):

Parathyroid Hormone ◽

Hormone Receptor ◽

Transmembrane Domain ◽

Receptor Activation ◽

Site Directed Mutagenesis ◽

Hereditary Diseases ◽

Dynamics Simulation ◽

Ligand Specificity ◽

Parathyroid Hormone Receptor ◽

N Terminus

The parathyroid hormone receptor 2 (PTH2R) is a class B1 G protein–coupled receptor (GPCR) involved in the regulation of calcium transport, nociception mediation, and wound healing. Naturally occurring mutations in PTH2R were reported to cause hereditary diseases, including syndromic short stature. Here, we report the cryogenic electron microscopy structure of PTH2R bound to its endogenous ligand, tuberoinfundibular peptide (TIP39), and a heterotrimeric Gs protein at a global resolution of 2.8 Å. The structure reveals that TIP39 adopts a unique loop conformation at the N terminus and deeply inserts into the orthosteric ligand-binding pocket in the transmembrane domain. Molecular dynamics simulation and site-directed mutagenesis studies uncover the basis of ligand specificity relative to three PTH2R agonists, TIP39, PTH, and PTH-related peptide. We also compare the action of TIP39 with an antagonist lacking six residues from the peptide N terminus, TIP(7-39), which underscores the indispensable role of the N terminus of TIP39 in PTH2R activation. Additionally, we unveil that a disease-associated mutation G258D significantly diminished cAMP accumulation induced by TIP39. Together, these results not only provide structural insights into ligand specificity and receptor activation of class B1 GPCRs but also offer a foundation to systematically rationalize the available pharmacological data to develop therapies for various disorders associated with PTH2R.

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Actions of the Small Molecule Ligands SW106 and AH-3960 on the Type-1 Parathyroid Hormone Receptor

Molecular Endocrinology ◽

10.1210/me.2014-1129 ◽

2015 ◽

Vol 29 (2) ◽

pp. 307-321 ◽

Cited By ~ 19

Author(s):

Percy H. Carter ◽

Thomas Dean ◽

Brijesh Bhayana ◽

Ashok Khatri ◽

Raj Rajur ◽

...

Keyword(s):

Parathyroid Hormone ◽

Small Molecule ◽

Hormone Receptor ◽

Transmembrane Domain ◽

Receptor Activation ◽

Blood Calcium ◽

Parathyroid Hormone Receptor ◽

Peptide Analog ◽

Amino Terminal ◽

Small Molecule Ligands

Abstract The parathyroid hormone receptor-1 (PTHR1) plays critical roles in regulating blood calcium levels and bone metabolism and is thus of interest for small-molecule ligand development. Of the few small-molecule ligands reported for the PTHR1, most are of low affinity, and none has a well-defined mechanism of action. Here, we show that SW106 and AH-3960, compounds previously identified to act as an antagonist and agonist, respectively, on the PTHR1, each bind to PTHR1-delNT, a PTHR1 construct that lacks the large amino-terminal extracellular domain used for binding endogenous PTH peptide ligands, with the same micromolar affinity with which it binds to the intact PTHR1. SW106 antagonized PTHR1-mediated cAMP signaling induced by the peptide analog, M-PTH(1–11), as well as by the native PTH(1–9) sequence, as tethered to the extracellular end of transmembrane domain (TMD) helix-1 of the receptor. SW106, however, did not function as an inverse agonist on either PTHR1-H223R or PTHR1-T410P, which have activating mutations at the cytoplasmic ends of TMD helices 2 and 6, respectively. The overall data indicate that SW106 and AH-3960 each bind to the PTHR1 TMD region and likely to within an extracellularly exposed area that is occupied by the N-terminal residues of PTH peptides. Additionally, they suggest that the inhibitory effects of SW106 are limited to the extracellular portions of the TMD region that mediate interactions with agonist ligands but do not extend to receptor-activation determinants situated more deeply in the helical bundle. The study helps to elucidate potential mechanisms of small-molecule binding at the PTHR1.

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New Members of the Parathyroid Hormone/Parathyroid Hormone Receptor Family: The Parathyroid Hormone 2 Receptor and Tuberoinfundibular Peptide of 39 Residues

Frontiers in Neuroendocrinology ◽

10.1006/frne.2000.0203 ◽

2000 ◽

Vol 21 (4) ◽

pp. 349-383 ◽

Cited By ~ 32

Author(s):

Ted B. Usdin ◽

Tianlun Wang ◽

Samuel R.J. Hoare ◽

Éva Mezey ◽

Miklós Palkovits

Keyword(s):

Parathyroid Hormone ◽

Hormone Receptor ◽

New Members ◽

Parathyroid Hormone Receptor ◽

Tuberoinfundibular Peptide ◽

Receptor Family

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Structure and dynamics of the active human parathyroid hormone receptor-1

Science ◽

10.1126/science.aav7942 ◽

2019 ◽

Vol 364 (6436) ◽

pp. 148-153 ◽

Cited By ~ 53

Author(s):

Li-Hua Zhao ◽

Shanshan Ma ◽

Ieva Sutkeviciute ◽

Dan-Dan Shen ◽

X. Edward Zhou ◽

...

Keyword(s):

Parathyroid Hormone ◽

G Protein ◽

Hormone Receptor ◽

Transmembrane Domain ◽

Transmembrane Helix ◽

Receptor Activation ◽

Structural Basis ◽

Parathyroid Hormone Receptor ◽

Class B ◽

Long Acting

The parathyroid hormone receptor-1 (PTH1R) is a class B G protein–coupled receptor central to calcium homeostasis and a therapeutic target for osteoporosis and hypoparathyroidism. Here we report the cryo–electron microscopy structure of human PTH1R bound to a long-acting PTH analog and the stimulatory G protein. The bound peptide adopts an extended helix with its amino terminus inserted deeply into the receptor transmembrane domain (TMD), which leads to partial unwinding of the carboxyl terminus of transmembrane helix 6 and induces a sharp kink at the middle of this helix to allow the receptor to couple with G protein. In contrast to a single TMD structure state, the extracellular domain adopts multiple conformations. These results provide insights into the structural basis and dynamics of PTH binding and receptor activation.

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