Discovering allatostatin type-C receptor specific agonists.

Currently, there is no pesticide available for the selective control of the pine processionary moth (Thaumetopoea pityocampa-specific), and conventional methods typically rely on mechanical techniques such as pheromone traps or broad-spectrum larvicidal chemicals. As climate change increases the range and dispersion capacity of crop and forest pests, outbreaks of the pine processionary occur with greater frequency and significantly impact forestry and public health. Our study is carried out to provide a T. pityocampa-specific pesticide targeting the Allatostatin Type-C Receptor (AlstR-C). We use a combination of computational biology methods, a cell-based screening assay, and in vivo toxicity and side effect assays to identify, for the first time, a series of AlstR-C ligands suitable for use as T. pityocampa-specific insecticides. We further demonstrate that the novel AlstR-C targeted agonists are specific to lepidopteran larvae, with no harmful effects on coleopteran larvae or adults. Overall, our study represents an important initial advance toward an insect GPCR-targeted next-generation pesticide design. Our approach may apply to other invertebrate GPCRs involved in vital metabolic pathways.

Update on the development of TGR5 agonists for human diseases.

The G protein-coupled bile acid receptor 1 (GPBAR1) or TGR5 is widely distributed across organs, including the small intestine, stomach, liver, spleen, and gallbladder. Many studies have established strong correlations between TGR5 and glucose homeostasis, energy metabolism, immune-inflammatory responses, and gastrointestinal functions. These results indicate that TGR5 has a significant impact on the progression of tumor development and metabolic disorders such as diabetes mellitus and obesity. Targeting TGR5 represents an encouraging therapeutic approach for treating associated human ailments. Notably, the GLP-1 receptor has shown exceptional efficacy in clinical settings for diabetes management and weight loss promotion. Currently, numerous TGR5 agonists have been identified through natural product-based approaches and virtual screening methods, with some successfully progressing to clinical trials. This review summarizes the intricate relationships between TGR5 and various diseases emphasizing recent advancements in research on TGR5 agonists, including their structural characteristics, design tactics, and biological activities. We anticipate that this meticulous review could facilitate the expedited discovery and optimization of novel TGR5 agonists.

Single-chain fluorescent integrators for mapping G-protein-coupled receptor agonists.

G protein-coupled receptors (GPCRs) transduce the effects of many neuromodulators including dopamine, serotonin, epinephrine, acetylcholine, and opioids. The localization of synthetic or endogenous GPCR agonists impacts their action on specific neuronal pathways. In this paper, we show a series of single-protein chain integrator sensors that are highly modular and could potentially be used to determine GPCR agonist localization across the brain. We previously engineered integrator sensors for the mu- and kappa-opioid receptor agonists called M- and K-Single-chain Protein-based Opioid Transmission Indicator Tool (SPOTIT), respectively. Here, we engineered red versions of the SPOTIT sensors for multiplexed imaging of GPCR agonists. We also modified SPOTIT to create an integrator sensor design platform called SPOTIT for all GPCRs (SPOTall). We used the SPOTall platform to engineer sensors for the beta 2-adrenergic receptor (B2AR), the dopamine receptor D1, and the cholinergic receptor muscarinic 2 agonists. Finally, we demonstrated the application of M-SPOTIT and B2AR-SPOTall in detecting exogenously administered morphine, isoproterenol, and epinephrine in the mouse brain via locally injected viruses. The SPOTIT and SPOTall sensor design platform has the potential for unbiased agonist detection of many synthetic and endogenous neuromodulators across the brain.

Discovery of a Novel Chemo-Type for TAAR1 Agonism via Molecular Modeling.

The search for novel effective TAAR1 ligands continues to draw great attention due to the wide range of pharmacological applications related to TAAR1 targeting. Herein, molecular docking studies of known TAAR1 ligands, characterized by an oxazoline core, have been performed in order to identify novel promising chemo-types for the discovery of more active TAAR1 agonists. In particular, the oxazoline-based compound S18616 has been taken as a reference compound for the computational study, leading to the development of quite flat and conformationally locked ligands. The choice of a "Y-shape" conformation was suggested for the design of TAAR1 ligands, interacting with the protein cavity delimited by ASP103 and aromatic residues such as PHE186, PHE195, PHE268, and PHE267. The obtained results allowed us to preliminary in silico screen an in-house series of pyrimidinone-benzimidazoles (1a-10a) as a novel scaffold to target TAAR1. Combined ligand-based (LBCM) and structure based (SBCM) computational methods suggested the biological evaluation of compounds 1a-10a, leading to the identification of derivatives 1a-3a (hTAAR1 EC50 = 526.3-657.4 nM) as promising novel TAAR1 agonists.

Predicting FFAR4 agonists using structure-based machine learning approach based on molecular fingerprints.

Free Fatty Acid Receptor 4 (FFAR4), a G-protein-coupled receptor, is responsible for triggering intracellular signaling pathways that regulate various physiological processes. FFAR4 agonists are associated with enhancing insulin release and mitigating the atherogenic, obesogenic, pro-carcinogenic, and pro-diabetogenic effects, normally associated with the free fatty acids bound to FFAR4. In this research, molecular structure-based machine-learning techniques were employed to evaluate compounds as potential agonists for FFAR4. Molecular structures were encoded into bit arrays, serving as molecular fingerprints, which were subsequently analyzed using the Bayesian network algorithm to identify patterns for screening the data. The shortlisted hits obtained via machine learning protocols were further validated by Molecular Docking and via ADME and Toxicity predictions. The shortlisted compounds were then subjected to MD Simulations of the membrane-bound FFAR4-ligand complexes for 100 ns each. Molecular analyses, encompassing binding interactions, RMSD, RMSF, RoG, PCA, and FEL, were conducted to scrutinize the protein-ligand complexes at the inter-atomic level. The analyses revealed significant interactions of the shortlisted compounds with the crucial residues of FFAR4 previously documented. FFAR4 as part of the complexes demonstrated consistent RMSDs, ranging from 3.57 to 3.64, with minimal residue fluctuations 5.27 to 6.03 nm, suggesting stable complexes. The gyration values fluctuated between 22.8 to 23.5 nm, indicating structural compactness and orderliness across the studied systems. Additionally, distinct conformational motions were observed in each complex, with energy contours shifting to broader energy basins throughout the simulation, suggesting thermodynamically stable protein-ligand complexes. The two compounds CHEMBL2012662 and CHEMBL64616 are presented as potential FFAR4 agonists, based on these insights and in-depth analyses. Collectively, these findings advance our comprehension of FFAR4's functions and mechanisms, highlighting these compounds as potential FFAR4 agonists worthy of further exploration as innovative treatments for metabolic and immune-related conditions.

Mas receptor activation facilitates innate hematoma resolution and neurological recovery after hemorrhagic stroke in mice.

BACKGROUND: Intracerebral hemorrhage (ICH) is a devastating neurological disease causing severe sensorimotor dysfunction and cognitive decline, yet there is no effective treatment strategy to alleviate outcomes of these patients. The Mas axis-mediated neuroprotection is involved in the pathology of various neurological diseases, however, the role of the Mas receptor in the setting of ICH remains to be elucidated. METHODS: C57BL/6 mice were used to establish the ICH model by injection of collagenase into mice striatum. The Mas receptor agonist AVE0991 was administered intranasally (0.9 mg/kg) after ICH. Using a combination of behavioral tests, Western blots, immunofluorescence staining, hematoma volume, brain edema, quantitative-PCR, TUNEL staining, Fluoro-Jade C staining, Nissl staining, and pharmacological methods, we examined the impact of intranasal application of AVE0991 on hematoma absorption and neurological outcomes following ICH and investigated the underlying mechanism. RESULTS: Mas receptor was found to be significantly expressed in activated microglia/macrophages, and the peak expression of Mas receptor in microglia/macrophages was observed at approximately 3-5 days, followed by a subsequent decline. Activation of Mas by AVE0991 post-treatment promoted hematoma absorption, reduced brain edema, and improved both short- and long-term neurological functions in ICH mice. Moreover, AVE0991 treatment effectively attenuated neuronal apoptosis, inhibited neutrophil infiltration, and reduced the release of inflammatory cytokines in perihematomal areas after ICH. Mechanistically, AVE0991 post-treatment significantly promoted the transformation of microglia/macrophages towards an anti-inflammatory, phagocytic, and reparative phenotype, and this functional phenotypic transition of microglia/macrophages by Mas activation was abolished by both Mas inhibitor A779 and Nrf2 inhibitor ML385. Furthermore, hematoma clearance and neuroprotective effects of AVE0991 treatment were reversed after microglia depletion in ICH. CONCLUSIONS: Mas activation can promote hematoma absorption, ameliorate neurological deficits, alleviate neuron apoptosis, reduced neuroinflammation, and regulate the function and phenotype of microglia/macrophages via Akt/Nrf2 signaling pathway after ICH. Thus, intranasal application of Mas agonist ACE0991 may provide promising strategy for clinical treatment of ICH patients.

Bitter taste receptor activation by cholesterol and an intracellular tastant.

Bitter taste sensing is mediated by type 2 taste receptors (TAS2Rs (also known as T2Rs)), which represent a distinct class of G-protein-coupled receptors1. Among the 26 members of the TAS2Rs, TAS2R14 is highly expressed in extraoral tissues and mediates the responses to more than 100 structurally diverse tastants2-6, although the molecular mechanisms for recognizing diverse chemicals and initiating cellular signalling are still poorly understood. Here we report two cryo-electron microscopy structures for TAS2R14 complexed with Ggust (also known as gustducin) and Gi1. Both structures have an orthosteric binding pocket occupied by endogenous cholesterol as well as an intracellular allosteric site bound by the bitter tastant cmpd28.1, including a direct interaction with the α5 helix of Ggust and Gi1. Computational and biochemical studies validate both ligand interactions. Our functional analysis identified cholesterol as an orthosteric agonist and the bitter tastant cmpd28.1 as a positive allosteric modulator with direct agonist activity at TAS2R14. Moreover, the orthosteric pocket is connected to the allosteric site via an elongated cavity, which has a hydrophobic core rich in aromatic residues. Our findings provide insights into the ligand recognition of bitter taste receptors and suggest activities of TAS2R14 beyond bitter taste perception via intracellular allosteric tastants.

Free fatty acid receptor 4 (FFA4) activation attenuates obese asthma by suppressing adiposity and resolving metaflammation.

Obese asthma is recognized to have different asthma phenotypes. N-3 polyunsaturated fatty acids (PUFAs) have shown beneficial effects in obesity and metabolic syndrome. Free fatty acid receptor 4 (FFA4, also known as GPR120) is a receptor for n-3 PUFAs. In the present study, we investigated whether FFA4 activation ameliorates high-fat diet (HFD)-induced obese asthma. We investigated whether FFA4 activation ameliorates obese asthma using an FFA4 agonist, compound A (CpdA), in combination with FFA4 wild-type (WT) and knock-out (KO) mice. Administration of an FFA4 agonist, compound A (CpdA, 30 mg/kg), suppressed HFD-induced weight gain, adiposity, and airway hypersensitivity (AHR), and increased immune cell infiltration in an FFA4-dependent manner. Histological analysis revealed that CpdA treatment suppressed HFD-induced mucus hypersecretion, inflammation, and fibrosis in an FFA4-dependent manner. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) showed an HFD-induced increase in the mRNA levels of pro-inflammatory cytokines in the lungs and gonadal white adipose tissue, whereas CpdA inhibited this increase in an FFA4-dependent manner. In the fluorescence-activated cell sorting (FACS) analysis, HFD induced an increase in the lung innate lymphoid cells (ILC) ILC1, ILC2, and ILC3; however, CpdA reversed this increase. In addition, HFD induced an increase in the pro-inflammatory M1 macrophage population and a decrease in the anti-inflammatory M2 macrophage population in the lungs, whereas CpdA treatment reversed these changes. The present study suggests that FFA4 activation may have therapeutic potential in obese asthma.

Computational modelling of dynamic cAMP responses to GPCR agonists for exploration of GLP-1R ligand effects in pancreatic ß-cells and neurons.

The glucagon-like peptide-1 receptor (GLP-1R) is a class B G protein-coupled receptor (GPCR) which plays important physiological roles in insulin release and promoting fullness. GLP-1R agonists initiate cellular responses by cyclic AMP (cAMP) pathway signal transduction. Understanding of the potential of GLP-1R agonists in the treatment of type 2 diabetes may be advanced by considering the cAMP dynamics for agonists at GLP-1R in both pancreatic ß-cells (important in insulin release) and neurons (important in appetite regulation). Receptor desensitisation in the cAMP pathway is known to be an important regulatory mechanism, with different ligands differentially promoting G protein activation and desensitisation. Here, we use mathematical modelling to quantify and understand experimentally obtained cAMP timecourses for two GLP-1R agonists, exendin-F1 (ExF1) and exendin-D3 (ExD3), which give markedly different signals in ß-cells and neurons. We formulate an ordinary differential equation (ODE) model for the dynamics of cAMP signalling in response to G protein-coupled receptor (GPCR) ligands, encompassing ligand binding, receptor activation, G protein activation, desensitisation and second messenger generation. We validate our model initially by fitting to timecourse data for HEK293 cells, then proceed to parameterise the model for ß-cells and neurons. Through numerical simulation and sensitivity studies, our analysis adds support to the hypothesis that ExF1 offers more potential glucose regulation benefit than ExD3 over long timescales via signalling in pancreatic ß-cells, but that there is little difference between the two ligands in the potential appetite suppression effects offered via long-time signalling in neurons on the same timescales.

Beyond the Nucleus: Plastic Chemicals Activate G Protein-Coupled Receptors.

G protein-coupled receptors (GPCRs) are central mediators of cell signaling and physiological function. Despite their biological significance, GPCRs have not been widely studied in the field of toxicology. Herein, we investigated these receptors as novel targets of plastic chemicals using a high-throughput drug screening assay with 126 human non-olfactory GPCRs. In a first-pass screen, we tested the activity of triphenol phosphate, bisphenol A, and diethyl phthalate, as well as three real-world mixtures of chemicals extracted from plastic food packaging covering all major polymer types. We found 11 GPCR-chemical interactions, of which the chemical mixtures exhibited the most robust activity at adenosine receptor 1 (ADORA1) and melatonin receptor 1 (MTNR1A). We further confirm that polyvinyl chloride and polyurethane products contain ADORA1 or MTNRA1 agonists using a confirmatory secondary screen and pharmacological knockdown experiments. Finally, an analysis of the associated gene ontology terms suggests that ADORA1 and MTNR1A activation may be linked to downstream effects on circadian and metabolic processes. This work highlights that signaling disruption caused by plastic chemicals is broader than that previously believed and demonstrates the relevance of nongenomic pathways, which have, thus far, remained unexplored.

Activation of free fatty acid receptors, FFAR1 and FFAR4, ameliorates ulcerative colitis by promote fatty acid metabolism and mediate macrophage polarization.

OBJECTIVE: To investigate the mechanism of action of fatty acid receptors, FFAR1 and FFAR4, on ulcerative colitis (UC) through fatty acid metabolism and macrophage polarization. METHODS: Dextran sulfate sodium (DSS)-induced mouse model of UC mice was used to evaluate the efficacy of FFAR1 (GW9508) and FFAR4 (GSK137647) agonists by analyzing body weight, colon length, disease activity index (DAI), and histological scores. Real-time PCR and immunofluorescence analysis were performed to quantify the levels of fatty acid metabolizing enzymes and macrophage makers. FFA-induced lipid accumulation in RAW264.7 cells was visualized by Oil Red O staining analysis, and cells were collected to detect macrophage polarization by flow cytometry. RESULTS: The combination of GW9508 and GSK137647 significantly improved DSS-induced UC symptoms, caused recovery in colon length, and decreased histological injury. GW9508 + GSK137647 treatment upregulated the expressions of CD206, lipid oxidation enzyme (CPT-1α) and anti-inflammatory cytokines (IL-4, IL-10, IL-13) but downregulated those of CD86, lipogenic enzymes (ACC1, FASN, SCD1), and pro-inflammatory cytokines (IL-1ß, IL-6, TNF-α). Combining the two agonists decreased FFA-induced lipid accumulation and increased CD206 expression in cell-based experiments. CONCLUSION: Activated FFAR1 and FFAR4 ameliorates DSS-induced UC by promoting fatty acid metabolism to reduce lipid accumulation and mediate M2 macrophage polarization.

Identification of Novel Series of Potent and Selective Relaxin Family Peptide Receptor 1 (RXFP1) Agonists.

Relaxin H2 is a clinically relevant peptide agonist for relaxin family peptide receptor 1 (RXFP1), but a combination of this hormone's short plasma half-life and the need for injectable delivery limits its therapeutic potential. We sought to overcome these limitations through the development of a potent small molecule (SM) RXFP1 agonist. Although two large SM HTS campaigns failed in identifying suitable hit series, we uncovered novel chemical space starting from the only known SM RXFP1 agonist series, represented by ML290. Following a design-make-test-analyze strategy based on improving early dose to man ranking, we discovered compound 42 (AZ7976), a highly selective RXFP1 agonist with sub-nanomolar potency. We used AZ7976, its 10 000-fold less potent enantiomer 43 and recombinant relaxin H2 to evaluate in vivo pharmacology and demonstrate that AZ7976-mediated heart rate increase in rats was a result of RXFP1 agonism. As a result, AZ7976 was selected as lead for continued optimization.

The GPR40 novel agonist SZZ15-11 improves non-alcoholic fatty liver disease by activating the AMPK pathway and restores metabolic homeostasis in diet-induced obese mice.

AIM: Non-alcoholic fatty liver is the most common cause of chronic liver disease. GPR40 is a potential therapeutic target for energy metabolic disorders. GPR40 is a potential therapeutic target for energy metabolic disorders. SZZ15-11 is a newly synthesized GPR40 agonist. In this study, we estimate the potency of SZZ15-11 in fatty liver treatment. METHODS: In vivo, diet-induced obese (DIO) mice received SZZ15-11 (50 mg/kg) and TAK875 (50 mg/kg) for 6 weeks. Blood glucose and lipid, hepatocyte lipid and liver morphology were analysed. In vitro, HepG2 cells and GPR40-knockdown HepG2 cells induced with 0.3 mM oleic acid were treated with SZZ15-11. Triglyceride and total cholesterol of cells were measured. At the same time, the AMPK pathway regulating triglycerides and cholesterol esters synthesis was investigated via western blot and quantitative polymerase chain reaction in both liver tissue and HepG2 cells. RESULTS: SZZ15-11 was found to not only attenuate hyperglycaemia and hyperlipidaemia but also ameliorate fatty liver disease in DIO mice. At the same time, SZZ15-11 decreased triglyceride and total cholesterol content in HepG2 cells. Whether examined in the liver of DIO mice or in HepG2 cells, SZZ15-11 upregulated AMPKα phosphorylation and then downregulated the expression of the cholesterogenic key enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase and inhibited acetyl-CoA carboxylase activity. Furthermore, SZZ15-11 promotes AMPK activity via [cAMP]i accumulation. CONCLUSION: This study confirmed that SZZ15-11, a novel GPR40 agonist, improves hyperlipidaemia and fatty liver, partially via Gs signalling and the AMPK pathway in hepatocytes.

TAAR1 agonist ulotaront delays gastric emptying of solids in patients with schizophrenia and concurrent metabolic syndrome with prediabetes.

BACKGROUND: Metabolic syndrome (MetS), which can be induced or exacerbated by the current class of antipsychotic drugs, is highly prevalent in patients with schizophrenia and presents significant challenges to lifetime disease management. Supported by initial clinical results, trace amine-associated receptor 1 (TAAR1) agonists have emerged as potential novel treatments for schizophrenia. Notably, non-clinical studies have also shown weight-lowering and glucoregulatory effects of TAAR1 agonists, including the investigational agent ulotaront. However, the translatability of these findings to humans has not been adequately assessed. Given that delayed gastric emptying (GE) was identified as a potential mechanism contributing to the metabolic benefits of TAAR1 agonists in rodents, the aim of this study was to evaluate the effect of ulotaront on GE in patients with schizophrenia and concurrent MetS with prediabetes. METHODS: Patients with schizophrenia were randomized to receive a single oral dose of ulotaront (150 mg) and their previous antipsychotic (PA) in an open-label, crossover, two-sequence design (NCT05402111). Eligible participants fulfilled at least three of five MetS criteria and had prediabetes defined by elevated glycated haemoglobin (5.7-6.4%) and/or fasting homeostatic model assessment of insulin resistance (i.e. ≥2.22). Following an overnight fast and 4 h post-dose, participants ingested a 99mTc-sulphur colloid radiolabelled egg meal (320 kcal, 30% fat). GE was measured by scintigraphy over 4 h. Endpoints included GE of solids half-time (T1/2) and percentage gastric retention at 1, 2 and 4 h. RESULTS: Thirty-one adults were randomized and 27 completed the study. Ulotaront significantly delayed GE of solids [median GE T1/2 ulotaront at 139 min (119, 182) vs. the participant's PA of 124 min (109, 132), p = .006]. A significant increase in gastric retention was seen in the ulotaront versus the PA group at 1 h (80% vs. 75%, p = .015), 2 h (61% vs. 50%, p = .023) and 4 h (17% vs. 7%, p = .002) post-meal. CONCLUSION: Ulotaront delayed the GE of solids in patients with schizophrenia and concurrent MetS with prediabetes. Additional studies are needed to assess whether treatment with TAAR1 agonists is associated with weight loss and glucoregulatory improvement.

MRGPRB2/X2 and the analogous effects of its agonist and antagonist in DSS-induced colitis in mice.

The mast cell receptor Mrgprb2, a mouse orthologue of human Mrgprx2, is known as an inflammatory receptor and its elevated expression is associated with various diseases such as ulcerative colitis. We aimed to elucidate the role of Mrgprb2/x2 and the effect of its ligands on a chemically induced murine colitis model. We showed that in Mrgprb2-/- mice, there is a differential regulation of cytokine releases in the blood plasma and severe colonic damages after DSS treatment. Unexpectedly, we demonstrated that known Mrgprb2/x2 agonists (peptide P17, P17 analogues and CST-14) and antagonist (GE1111) similarly increased the survival rate of WT mice subjected to 4% DSS-induced colitis, ameliorated the colonic damages of 2.5% DSS-induced colitis, restored major protein mRNA expression involved in colon integrity, reduced CD68+ and F4/80+ immune cell infiltration and restored cytokine levels. Collectively, our findings highlight the eminent role of Mrpgrb2/x2 in conferring a beneficial effect in the colitis model, and this significance is demonstrated by the heightened severity of colitis with altered cytokine releases and inflammatory immune cell infiltration observed in the Mrgprb2 knockout mice. Elevated expression of Mrgprb2 in WT colitis murine models may represent the organism's adaptive protective mechanism since Mrgprb2 knockout results in severe colitis. On the other hand, both agonist and antagonist of Mrgprb2 analogously mitigated the severity of colitis in DSS-induced colitis model by altering Mrgprb2 expression, immune cell infiltration and inflammatory cytokine releases.

GPR119 agonists for type 2 diabetes: past failures and future hopes for preclinical and early phase candidates.

INTRODUCTION: Type 2 diabetes (T2D) is metabolic disorder associated with a decrease in insulin activity and/or secretion from the ß-cells of the pancreas, leading to elevated circulating glucose. Current management practices for T2D are complex with varying long-term effectiveness. Agonism of the G protein-coupled receptor GPR119 has received a lot of recent interest as a potential T2D therapeutic. AREAS COVERED: This article reviews studies focused on GPR119 agonism in animal models of T2D and in patients with T2D. EXPERT OPINION: GPR119 agonists in vitro and in vivo can potentially regulate incretin hormone release from the gut, then pancreatic insulin release which regulates blood glucose concentrations. However, the success in controlling glucose homeostasis in rodent models of T2D and obesity, failed to translate to early-stage clinical trials in patients with T2D. However, in more recent studies, acute and chronic dosing with the GPR119 agonist DS-8500a had increased efficacy, although this compound was discontinued for further development. New trials on GPR119 agonists are needed, however it may be that the future of GPR119 agonists lie in the development of combination therapy with other T2D therapeutics.

Design, Synthesis, and Structure-Activity Relationship Studies of Novel GPR88 Agonists (4-Substituted-phenyl)acetamides Based on the Reversed Amide Scaffold.

The development of synthetic agonists for the orphan receptor GPR88 has recently attracted significant interest, given the promise of GPR88 as a novel drug target for psychiatric and neurodegenerative disorders. Examination of structure-activity relationships of two known agonist scaffolds 2-PCCA and 2-AMPP, as well as the recently resolved cryo-EM structure of 2-PCCA-bound GPR88, led to the design of a new scaffold based on the "reversed amide" strategy of 2-AMPP. A series of novel (4-substituted-phenyl)acetamides were synthesized and assessed in cAMP accumulation assays as GPR88 agonists, which led to the discovery of several compounds with better or comparable potencies to 2-AMPP. Computational docking studies suggest that these novel GPR88 agonists bind to the same allosteric site of GPR88 that 2-PCCA occupies. Collectively, our findings provide structural insight and SAR requirement at the allosteric site of GPR88 and a new scaffold for further development of GPR88 allosteric agonists.

Synthetic GPR40/FFAR1 agonists: An exhaustive survey on the most recent chemical classes and their structure-activity relationships.

Free fatty acid receptor 1 (FFAR1 or GPR40) is a potential target for treating type 2 diabetes mellitus (T2DM) and related disorders that have been extensively researched for many years. GPR40/FFAR1 is a promising anti-diabetic target because it can activate insulin, promoting glucose metabolism. It controls T2DM by regulating glucose levels in the body through two separate mechanisms: glucose-stimulated insulin secretion and incretin production. In the last few years, various synthetic GPR40/FFAR1 agonists have been discovered that fall under several chemical classes, viz. phenylpropionic acid, phenoxyacetic acid, and dihydrobenzofuran acetic acid. However, only a few synthetic agonists have entered clinical trials due to various shortcomings like poor efficacy, low lipophilicity and toxicity issues. As a result, pharmaceutical firms and research institutions are interested in developing synthetic GPR40/FFAR1 agonists with superior effectiveness, lipophilicity, and safety profiles. This review encompasses the most recent research on synthetic GPR40/FFAR1 agonists, including their chemical classes, design strategies and structure-activity relationships. Additionally, we have emphasised the structural characteristics of the most potent GPR40/FFAR1 agonists from each chemical class of synthetic derivatives and analysed their chemico-biological interactions. This work will hopefully pave the way for developing more potent and selective synthetic GPR40/FFAR1 agonists for treating T2DM and related disorders.

An LGR4 agonist activates the GSK­3ß pathway to inhibit RANK­RANKL signaling during osteoclastogenesis in bone marrow­derived macrophages.

The binding between receptor­activated nuclear factor­κB (RANK) and the RANK ligand (RANKL) during osteoclast development is an important target for drugs that treat osteoporosis. The leucine­rich repeat­containing G­protein­coupled receptor 4 (LGR4) acts as a negative regulator of RANK­RANKL that suppresses canonical RANK signaling during osteoclast differentiation. Therefore, LGR4 agonists may be useful in inhibiting osteoclastogenesis and effectively treating osteoporosis. In the present study, bone marrow­derived macrophages and a mouse model of RANKL­induced bone loss were used to investigate the effect of mutant RANKL (MT RANKL), which was previously developed based on the crystal structure of the RANKL complex. In the present study, the binding affinity of wild­type (WT) RANKL and MT RANKL to RANK and LGR4 was determined using microscale thermophoresis analysis, and the effect of the ligands on the AKT­glycogen synthase kinase­3ß (GSK­3ß)­nuclear factor of activated T cells, cytoplasmic, calcineurin­dependent 1 (NFATc1) signaling cascade was investigated using western blotting and confocal microscopy. In addition, the expression of LGR4 and the colocalization of LGR4 with MT RANKL were analyzed in a mouse model of RANKL­induced bone loss. The results showed that in osteoclast precursor cells, MT RANKL bound with high affinity to LGR4 and increased GSK­3ß phosphorylation independently of AKT, resulting in the inhibition of NFATc1 nuclear translocation. In the mouse model, MT RANKL colocalized with LGR4 and inhibited bone resorption. These results indicated that MT RANKL may inhibit RANKL­induced osteoclastogenesis through an LGR4­dependent pathway and this could be exploited to develop new therapies for osteoporosis.