scholarly journals Structural basis for GLP-1 receptor activation by LY3502970, an orally active nonpeptide agonist

2020 ◽  
Vol 117 (47) ◽  
pp. 29959-29967 ◽  
Author(s):  
Takahiro Kawai ◽  
Bingfa Sun ◽  
Hitoshi Yoshino ◽  
Dan Feng ◽  
Yoshiyuki Suzuki ◽  
...  
Keyword(s):  
Oral Administration ◽  
G Protein ◽  
Partial Agonist ◽  
Pharmacokinetic Profile ◽  
Binding Pocket ◽  
Receptor Activation ◽  
Structural Basis ◽  
Protein Activation ◽  
Class B ◽  
Glucagon Like Peptide 1

Glucagon-like peptide-1 receptor (GLP-1R) agonists are efficacious antidiabetic medications that work by enhancing glucose-dependent insulin secretion and improving energy balance. Currently approved GLP-1R agonists are peptide based, and it has proven difficult to obtain small-molecule activators possessing optimal pharmaceutical properties. We report the discovery and mechanism of action of LY3502970 (OWL833), a nonpeptide GLP-1R agonist. LY3502970 is a partial agonist, biased toward G protein activation over β-arrestin recruitment at the GLP-1R. The molecule is highly potent and selective against other class B G protein–coupled receptors (GPCRs) with a pharmacokinetic profile favorable for oral administration. A high-resolution structure of LY3502970 in complex with active-state GLP-1R revealed a unique binding pocket in the upper helical bundle where the compound is bound by the extracellular domain (ECD), extracellular loop 2, and transmembrane helices 1, 2, 3, and 7. This mechanism creates a distinct receptor conformation that may explain the partial agonism and biased signaling of the compound. Further, interaction between LY3502970 and the primate-specific Trp33 of the ECD informs species selective activity for the molecule. In efficacy studies, oral administration of LY3502970 resulted in glucose lowering in humanized GLP-1R transgenic mice and insulinotropic and hypophagic effects in nonhuman primates, demonstrating an effect size in both models comparable to injectable exenatide. Together, this work determined the molecular basis for the activity of an oral agent being developed for the treatment of type 2 diabetes mellitus, offering insights into the activation of class B GPCRs by nonpeptide ligands.

scholarly journals Structural insights into ligand efficacy and activation of the glucagon receptor

2019 ◽  
Author(s):  
Daniel Hilger ◽  
Kaavya Krishna Kumar ◽  
Hongli Hu ◽  
Mie Fabricius Pedersen ◽  
Lise Giehm ◽  
...  
Keyword(s):  
G Protein ◽  
Partial Agonist ◽  
Transmembrane Helix ◽  
Peptide Hormone ◽  
Receptor Activation ◽  
Glucagon Receptor ◽  
Structural Framework ◽  
Class B ◽  
Treatment Of Diabetes ◽  
Sugar Levels

AbstractThe glucagon receptor family comprises Class B G protein-coupled receptors (GPCRs) that play a crucial role in regulating blood sugar levels. Receptors of this family represent important therapeutic targets for the treatment of diabetes and obesity. Despite intensive structural studies, we only have a poor understanding of the mechanism of peptide hormone-induced Class B receptor activation. This process involves the formation of a sharp kink in transmembrane helix 6 that moves out to allow formation of the nucleotide-free G protein complex. Here, we present the cryo-EM structure of the glucagon receptor (GCGR), a prototypical Class B GPCR, in complex with an engineered soluble glucagon derivative and the heterotrimeric G-protein, Gs. Comparison with the previously determined crystal structures of GCGR bound to a partial agonist reveals a structural framework to explain the molecular basis of ligand efficacy that is further supported by mutagenesis data.

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

Science ◽  
2019 ◽  
Vol 364 (6436) ◽  
pp. 148-153 ◽  
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.

scholarly journals Cryo-EM structure of the human PAC1 receptor coupled to an engineered heterotrimeric G protein

2019 ◽  
Author(s):  
Kazuhiro Kobayashi ◽  
Wataru Shihoya ◽  
Tomohiro Nishizawa ◽  
Francois Marie Ngako Kadji ◽  
Junken Aoki ◽  
...  
Keyword(s):  
G Protein ◽  
Structural Information ◽  
Receptor Activation ◽  
Peptide Ligand ◽  
Pac1 Receptor ◽  
Peripheral Tissues ◽  
Class B ◽  
Neuropeptide Hormone ◽  
The Central Nervous System ◽  
Glucagon Like Peptide 1

AbstractPituitary adenylate cyclase-activating polypeptide (PACAP) is a pleiotropic neuropeptide hormone functioning in the central nervous system and peripheral tissues. The PACAP receptor PAC1R, which belongs to the class B G-protein-coupled receptors (GPCRs), is a drug target for mental disorders and dry eye syndrome. Here we present a cryo-electron microscopy structure of human PAC1R bound to PACAP and an engineered Gs heterotrimer. The structure revealed that TM1 plays an essential role in PACAP recognition. The ECD (extracellular domain) of PAC1R tilts by ~40° as compared to that of the glucagon-like peptide-1 receptor (GLP1R), and thus does not cover the peptide ligand. A functional analysis demonstrated that the PAC1R-ECD functions as an affinity trap and is not required for receptor activation, whereas the GLP1R-ECD plays an indispensable role in receptor activation, illuminating the functional diversity of the ECDs in the class B GPCRs. Our structural information will facilitate the design and improvement of better PAC1R agonists for clinical applications.This article is a preprint version and has not been certified by peer review.

scholarly journals Low intrinsic efficacy for G protein activation can explain the improved side effect profiles of new opioid agonists

2020 ◽  
Vol 13 (625) ◽  
pp. eaaz3140 ◽  
Author(s):  
Alexander Gillis ◽  
Arisbel B. Gondin ◽  
Andrea Kliewer ◽  
Julie Sanchez ◽  
Herman D. Lim ◽  
...  
Keyword(s):  
G Protein ◽  
Side Effect ◽  
Opioid Analgesics ◽  
Receptor Activation ◽  
Alternative Mechanism ◽  
Protein Activation ◽  
Biased Agonism ◽  
Opioid Ligands ◽  
Intrinsic Efficacy ◽  
Respiratory Depressant

Biased agonism at G protein–coupled receptors describes the phenomenon whereby some drugs can activate some downstream signaling activities to the relative exclusion of others. Descriptions of biased agonism focusing on the differential engagement of G proteins versus β-arrestins are commonly limited by the small response windows obtained in pathways that are not amplified or are less effectively coupled to receptor engagement, such as β-arrestin recruitment. At the μ-opioid receptor (MOR), G protein–biased ligands have been proposed to induce less constipation and respiratory depressant side effects than opioids commonly used to treat pain. However, it is unclear whether these improved safety profiles are due to a reduction in β-arrestin–mediated signaling or, alternatively, to their low intrinsic efficacy in all signaling pathways. Here, we systematically evaluated the most recent and promising MOR-biased ligands and assessed their pharmacological profile against existing opioid analgesics in assays not confounded by limited signal windows. We found that oliceridine, PZM21, and SR-17018 had low intrinsic efficacy. We also demonstrated a strong correlation between measures of efficacy for receptor activation, G protein coupling, and β-arrestin recruitment for all tested ligands. By measuring the antinociceptive and respiratory depressant effects of these ligands, we showed that the low intrinsic efficacy of opioid ligands can explain an improved side effect profile. Our results suggest a possible alternative mechanism underlying the improved therapeutic windows described for new opioid ligands, which should be taken into account for future descriptions of ligand action at this important therapeutic target.

scholarly journals Structural basis for GPCR-independent activation of heterotrimeric Gi proteins

2019 ◽  
Vol 116 (33) ◽  
pp. 16394-16403 ◽  
Author(s):  
Nicholas A. Kalogriopoulos ◽  
Steven D. Rees ◽  
Tony Ngo ◽  
Noah J. Kopcho ◽  
Andrey V. Ilatovskiy ◽  
...  
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Structural Changes ◽  
Control Cell ◽  
Structural Basis ◽  
Common Mechanism ◽  
Hydrophobic Core ◽  
Nucleotide Exchange ◽  
Protein Activation ◽  
G Protein Activation

Heterotrimeric G proteins are key molecular switches that control cell behavior. The canonical activation of G proteins by agonist-occupied G protein-coupled receptors (GPCRs) has recently been elucidated from the structural perspective. In contrast, the structural basis for GPCR-independent G protein activation by a novel family of guanine-nucleotide exchange modulators (GEMs) remains unknown. Here, we present a 2.0-Å crystal structure of Gαi in complex with the GEM motif of GIV/Girdin. Nucleotide exchange assays, molecular dynamics simulations, and hydrogen–deuterium exchange experiments demonstrate that GEM binding to the conformational switch II causes structural changes that allosterically propagate to the hydrophobic core of the Gαi GTPase domain. Rearrangement of the hydrophobic core appears to be a common mechanism by which GPCRs and GEMs activate G proteins, although with different efficiency. Atomic-level insights presented here will aid structure-based efforts to selectively target the noncanonical G protein activation.

The orthosteric agonist-binding pocket in the prototypic class B G-protein-coupled secretin receptor

2013 ◽  
Vol 41 (1) ◽  
pp. 154-158 ◽  
Author(s):  
Laurence J. Miller ◽  
Maoqing Dong
Keyword(s):  
G Protein ◽  
Fluorescence Analysis ◽  
Binding Pocket ◽  
Rational Development ◽  
Secretin Receptor ◽  
Natural Ligands ◽  
Class B ◽  
G Protein Coupled ◽  
Moderate Length ◽  
Activity Series

Class B GPCRs (G-protein-coupled receptors) share heptahelical topology and G-protein binding with other superfamily members, yet have unique structures and modes of activation. Natural ligands for these receptors are moderate-length peptides with C-terminal α-helices. NMR and crystal structures of the peptide-bound disulfide-bonded receptor N-terminal domains demonstrate that these helices occupy a conserved groove; however, the details of this interaction vary from one receptor to another. In this review, we focus on the prototypic secretin receptor and use extensive intrinsic photoaffinity labelling, structure–activity series, alanine-replacement mutagenesis and fluorescence analysis to define the molecular basis for this interaction. Additionally, experimental validation of predictions coming from in silico molecular modelling has provided a basis for enhancement of binding affinity. Such insights will be useful in the rational development of drugs acting at this important group of targets.

scholarly journals Dynamics of GLP-1R peptide agonist engagement are correlated with kinetics of G protein activation

2021 ◽  
Author(s):  
Giuseppe Deganutti ◽  
Yi-Lynn Liang ◽  
Xin Zhang ◽  
Maryam Khoshouei ◽  
Lachlan Clydesdale ◽  
...  
Keyword(s):  
G Protein ◽  
Transmembrane Domain ◽  
Protein Activation ◽  
G Protein Activation ◽  
Binding Cavity ◽  
Transient Interactions ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Dynamics Simulations ◽  
Peptide Agonist

ABSTRACTThe glucagon-like peptide-1 receptor (GLP-1R) has broad physiological roles and is a validated target for treatment of metabolic disorders. Despite recent advances in GLP-1R structure elucidation, detailed mechanistic understanding of how different peptides generate profound differences in G protein-mediated signalling is still lacking. Here we have combined cryo-electron microscopy, molecular dynamics simulations, receptor mutagenesis and pharmacological assays, to interrogate the mechanism and consequences of GLP-1R binding by four peptide agonists; glucagon-like peptide-1, oxyntomodulin, exendin-4 and exendin-P5. These data revealed that distinctions in peptide N-terminal interactions and dynamics with the GLP-1R transmembrane domain are reciprocally associated with differences in the allosteric coupling to G proteins. In particular, transient interactions with residues at the base of the binding cavity correlate with enhanced kinetics for G protein activation, providing a rationale for differences in G protein-mediated signalling efficacy from distinct agonists.

scholarly journals Structural basis of bile acid receptor activation and Gs coupling

2020 ◽  
Author(s):  
Fan Yang ◽  
Chunyou Mao ◽  
Lulu Guo ◽  
Jingyu Lin ◽  
Qianqian Ming ◽  
...  
Keyword(s):  
Bile Acid ◽  
Ligand Binding ◽  
Bile Acids ◽  
G Protein ◽  
Binding Pocket ◽  
Receptor Activation ◽  
Structural Features ◽  
Ligand Binding Pocket ◽  
Bile Acid Receptor ◽  
Key Residues

AbstractG protein-coupled bile acid receptor (GPBAR) is a membrane receptor that senses bile acids to regulate diverse functions through Gs activation. Here, we report the cryo-EM structures of GPBAR–Gs complexes stabilized by either high-affinity P395 or the semisynthesized bile acid derivative INT-777 at 3-Å resolution. These structures revealed a large oval-shaped ligand pocket with several sporadic polar groups to accommodate the amphipathic cholic core of bile acids. A fingerprint of key residues recognizing diverse bile acids in the orthosteric site, a putative second bile acid binding site with allosteric properties and structural features contributing to bias property were identified through structural analysis and mutagenesis studies. Moreover, structural comparison of GPBAR with other GPCRs uncovered an atypical mode of receptor activation and G-protein– coupling, featuring a different set of key residues connecting the ligand binding pocket to the Gs coupling site, and a specific interaction motif localized in intracellular loop 3. Overall, our study not only provides unique structural features of GPBAR in bile acid recognition, allosteric effects and biased signaling, but also suggests that distinct allosteric connecting mechanisms between the ligand binding pocket and the G protein binding site exist in the GPCR superfamily.

scholarly journals Receptor-wide Determinants of G Protein Coupling Selectivity in Aminergic GPCRs

2021 ◽  
Author(s):  
Berkay Selçuk ◽  
Ismail Erol ◽  
Serdar Durdağı ◽  
Ogun Adebali
Keyword(s):  
Ligand Binding ◽  
G Protein ◽  
Md Simulations ◽  
Binding Pocket ◽  
Receptor Activation ◽  
Selective Activation ◽  
G Protein Coupling ◽  
Protein Coupling ◽  
Gpcr Activation ◽  
Activation Mechanisms

AbstractG protein-coupled receptors (GPCRs) induce signal transduction pathways through coupling to four main subtypes of G proteins (Gs, Gi, Gq, G12/13), selectively. However, G protein selective activation mechanisms and residual determinants in GPCRs have remained obscure. Here, we identified conserved G protein selective activation mechanisms determining receptors’ ability to couple to a type of G protein. Herein, we performed an extensive phylogenetic analysis and identified specifically conserved residues for the receptors having similar coupling profiles in each aminergic receptor. By integrating our methodology of differential evolutionary conservation of G protein-specific amino acids with structural analyses, we identified selective activation networks for Gs, Gi1, Go, and Gq. We found that G protein selectivity is determined by not only the G protein interaction site but also other parts of the receptor including the ligand binding pocket. To validate our findings, we further studied an amino acid residue that we revealed as a selectivity-determining in Gs coupling and performed molecular dynamics (MD) simulations. We showed that previously uncharacterized Glycine at position 7×41 plays an important role in both receptor activation and Gs coupling. Finally, we gathered our results into a comprehensive model of G protein selectivity called “sequential switches of activation” describing three main molecular switches controlling GPCR activation: ligand binding, G protein selective activation mechanisms and G protein contact. We believe that our work provides a broader view on receptor-level determinants of G protein coupling selectivity.

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