October 2022 Mechanism of enhanced sensitivity of mutated β-adrenergic-like octopamine receptor to amitraz in honeybee Apis mellifera: An insight from MD simulations "Background: Amitraz is one of the critical acaricides/insecticides for effective control of pest infestation of Varroa destructor mite, a devastating parasite of Apis mellifera, because of its low toxicity to honeybees. Previous assays verified that a typical G protein-coupled receptor, β-adrenergic-like octopamine receptor (Octβ2R), is the unique target of amitraz, but the honeybee Octβ2R resists to amitraz. However, the underlying molecular mechanism of the enhanced sensitivity or toxicity of amitraz to mutated honeybee Octβ2RE208V/I335T/I350V is not fully understood. Here, molecular dynamics simulations are employed to explore the implied mechanism of the enhanced sensitivity to amitraz in mutant honeybee Octβ2R." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 "Alzheimer's disease (AD) is the most common dementia in the elderly and its increasing prevalence presents treatment challenges. Despite a better understanding of the disease, the current mainstay of treatment cannot modify pathogenesis or effectively address the associated cognitive and memory deficits. Emerging evidence suggests adenosine G protein-coupled receptors (GPCRs) are promising therapeutic targets for Alzheimer's disease. The adenosine A1 and A2A receptors are expressed in the human brain and have a proposed involvement in the pathogenesis of dementia. Targeting these receptors preclinically can mitigate pathogenic β-amyloid and tau neurotoxicity whilst improving cognition and memory. In this review, we provide an accessible summary of the literature on Alzheimer's disease and the therapeutic potential of A1 and A2A receptors. Although there are no available medicines targeting these receptors approved for treating dementia, we provide insights into some novel strategies, including allosterism and the targeting of oligomers, which may increase drug discovery success and enhance the therapeutic response." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Focusing on the role of secretin/adhesion (Class B) G protein-coupled receptors in placental development and preeclampsia "Preeclampsia, a clinical syndrome mainly characterized by hypertension and proteinuria, with a worldwide incidence of 3–8% and high maternal mortality, is a risk factor highly associated with maternal and offspring cardiovascular disease. However, the etiology and pathogenesis of preeclampsia are complicated and have not been fully elucidated. Obesity, immunological diseases and endocrine metabolic diseases are high-risk factors for the development of preeclampsia. Effective methods to treat preeclampsia are lacking, and termination of pregnancy remains the only curative treatment for preeclampsia. The pathogenesis of preeclampsia include poor placentation, uteroplacental malperfusion, oxidative stress, endoplasmic reticulum stress, dysregulated immune tolerance, vascular inflammation and endothelial cell dysfunction. The notion that placenta is the core factor in the pathogenesis of preeclampsia is still prevailing. G protein-coupled receptors, the largest family of membrane proteins in eukaryotes and the largest drug target family to date, exhibit diversity in structure and function. Among them, the secretin/adhesion (Class B) G protein-coupled receptors are essential drug targets for human diseases, such as endocrine diseases and cardiometabolic diseases. Given the great value of the secretin/adhesion (Class B) G protein-coupled receptors in the regulation of cardiovascular system function and the drug target exploration, we summarize the role of these receptors in placental development and preeclampsia, and outlined the relevant pathological mechanisms, thereby providing potential drug targets for preeclampsia treatment." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Membrane Lipids Are an Integral Part of Transmembrane Allosteric Sites in GPCRs: A Case Study of Cannabinoid CB1 Receptor Bound to a Negative Allosteric Modulator, ORG27569, and Analogs "A growing number of G-protein-coupled receptor (GPCR) structures reveal novel transmembrane lipid-exposed allosteric sites. Ligands must first partition into the surrounding membrane and take lipid paths to these sites. Remarkably, a significant part of the bound ligands appears exposed to the membrane lipids. The experimental structures do not usually account for the surrounding lipids, and their apparent contribution to ligand access and binding is often overlooked and poorly understood. Using classical and enhanced molecular dynamics simulations, we show that membrane lipids are critical in the access and binding of ORG27569 and its analogs at the transmembrane site of cannabinoid CB1 receptor. The observed differences in the binding affinity and cooperativity arise from the functional groups that interact primarily with lipids. Our results demonstrate the significance of incorporating membrane lipids as an integral component of transmembrane sites for accurate characterization, binding-affinity calculations, and lead optimization in drug discovery." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Genome-scale CRISPR screening reveals that C3aR signaling is critical for rapid capture of fungi by macrophages "The fungal pathogen Histoplasma capsulatum (Hc) invades, replicates within, and destroys macrophages. To interrogate the molecular mechanisms underlying this interaction, we conducted a host-directed CRISPR-Cas9 screen and identified 361 genes that modify macrophage susceptibility to Hc infection, greatly expanding our understanding of host gene networks targeted by Hc. We identified pathways that have not been previously implicated in Hc interaction with macrophages, including the ragulator complex (involved in nutrient stress sensing), glycosylation enzymes, protein degradation machinery, mitochondrial respiration genes, solute transporters, and the ER membrane complex (EMC). The highest scoring protective hits included the complement C3a receptor (C3aR), a G-protein coupled receptor (GPCR) that recognizes the complement fragment C3a. Although it is known that complement components react with the fungal surface, leading to opsonization and release of small peptide fragments such as C3a, a role for C3aR in macrophage interactions with fungi has not been elucidated. We demonstrated that whereas C3aR is dispensable for macrophage phagocytosis of bacteria and latex beads, it is critical for optimal macrophage capture of pathogenic fungi, including Hc, the ubiquitous fungal pathogen Candida albicans, and the causative agent of Valley Fever Coccidioides posadasii. We showed that C3aR localizes to the early phagosome during Hc infection where it coordinates the formation of actin-rich membrane protrusions that promote Hc capture. We also showed that the EMC promotes surface expression of C3aR, likely explaining its identification in our screen. Taken together, our results provide new insight into host processes that affect Hc-macrophage interactions and uncover a novel and specific role for C3aR in macrophage recognition of fungi." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Keratinocyte-derived defensins activate neutrophil-specific receptors Mrgpra2a/b to prevent skin dysbiosis and bacterial infection "Healthy skin maintains a diverse microbiome and a potent immune system to fight off infections. Here, we discovered that the epithelial-cell-derived antimicrobial peptides defensins activated orphan G-protein-coupled receptors (GPCRs) Mrgpra2a/b on neutrophils. This signaling axis was required for effective neutrophil-mediated skin immunity and microbiome homeostasis. We generated mutant mouse lines lacking the entire Defensin (Def) gene cluster in keratinocytes or Mrgpra2a/b. Def and Mrgpra2 mutant animals both exhibited skin dysbiosis, with reduced microbial diversity and expansion of Staphylococcus species. Defensins and Mrgpra2 were critical for combating S. aureus infections and the formation of neutrophil abscesses, a hallmark of antibacterial immunity. Activation of Mrgpra2 by defensin triggered neutrophil release of IL-1β and CXCL2 which are vital for proper amplification and propagation of the antibacterial immune response. This study demonstrated the importance of epithelial-neutrophil signaling via the defensin-Mrgpra2 axis in maintaining healthy skin ecology and promoting antibacterial host defense." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 "Recently determined structures of class C G protein-coupled receptors (GPCRs) revealed the location of allosteric binding sites and opened new opportunities for the discovery of novel modulators. In this work, molecular docking screens for allosteric modulators targeting the metabotropic glutamate receptor 5 (mGlu5) were performed. The mGlu5 receptor is activated by the main excitatory neurotransmitter of the nervous central system, L-glutamate, and mGlu5 receptor activity can be allosterically modulated by negative or positive allosteric modulators. The mGlu5 receptor is a promising target for the treatment of psychiatric and neurodegenerative diseases, and several allosteric modulators of this GPCR have been evaluated in clinical trials. Chemical libraries containing fragment- (1.6 million molecules) and lead-like (4.6 million molecules) compounds were docked to an allosteric binding site of mGlu5 identified in X-ray crystal structures. Among the top-ranked compounds, 59 fragments and 59 lead-like compounds were selected for experimental evaluation. Of these, four fragment- and seven lead-like compounds were confirmed to bind to the allosteric site with affinities ranging from 0.43 to 8.6 μM, corresponding to a hit rate of 9%. The four compounds with the highest affinities were demonstrated to be negative allosteric modulators of mGlu5 signaling in functional assays. The results demonstrate that virtual screens of fragment- and lead-like chemical libraries have complementary advantages and illustrate how access to high-resolution structures of GPCRs in complex with allosteric modulators can accelerate lead discovery." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 GPR15 expressed in T lymphocytes from RA patients is involved in leukocyte chemotaxis to the synovium "The rheumatoid arthritis (RA) inflammatory process occurs in the joints where immune cells are attracted into the synovium to promote remodeling and tissue damage. GPR15 is a G protein-coupled receptor (GPCR) located on chromosome 3 and has similarity in its sequence with chemokine receptors. Recent evidence indicates that GPR15 may be associated with modulation of the chronic inflammatory response. We evaluated the expression of GPR15 and GPR15L in blood and synovial tissue samples from RA patients, as well as to perform a functional migration assay in response to GPR15L. The expression of GPR15 and c10orf99/gpr15l mRNA was analyzed by RT-qPCR. Samples of synovial fluid and peripheral blood were analyzed for CD45+CD3+CD4+GPR15+ and CD45+CD3+CD8+GPR15+ T cell frequency comparing RA patients versus control subjects by flow cytometry. Migration assays were performed using PBMCs isolated from these individuals in response to the synthetic GPR15 ligand. Statistical analysis included Kruskal-Wallis test, T-test, or Mann-Whitney U test, according to data distribution. A higher expression in the mRNA for GPR15 was identified in early RA subjects. The frequencies of CD4+/CD8+ GPR15+ T lymphocytes are higher in RA patients comparing with healthy subjects. Also, the frequency CD4+/CD8+ GPR15+ T lymphocytes are higher in synovial fluid of established RA patients comparing with OA patients. GPR15 and GPR15L are present in the synovial tissue of RA patients and GPR15L promotes migration of PBMCs from RA patients and healthy subjects. Our results suggest that GPR15/GPR15L have a pathogenic role in RA and their antagonizing could be a therapeutic approach in RA." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Successful prednisolone or calcimimetic treatment of acquired hypocalciuric hypercalcemia caused by biased allosteric CaSR autoantibodies "Biased agonism is a frontier field in GPCR research. Acquired hypocalciuric hypercalcemia (AHH) is a rare disease caused by calcium-sensing receptor (CaSR) autoantibodies, to date, showing either simple blocking or biased properties (i.e., stimulatory or blocking effects on different downstream signaling pathways). This emphasizes the importance of the Gi/o (pertussis toxin-sensitive G proteins, whose βγ subunits activate multiple signals, including ERK1/2) in regulating parathyroid hormone secretion. We here describe 3 patients with symptomatic AHH who shared characteristics with the 2 cases we previously reported as follows: (a) elderly (74-87 years at diagnosis), (b) male, (c) unexpectedly showed no other autoimmune diseases, (d) showed spontaneously fluctuating Ca levels from approximately normal to near fatally high ranges, (e) acute exacerbations could be successfully treated with prednisolone and/or calcimimetics, (f) the presence of CaSR autoantibodies that operated as biased allosteric modulators of CaSR, and (g) were likely to be conformational (i.e., recognizing and, thereby, stabilizing a unique active conformation of CaSR that activates Gq/11, activating phosphatidylinositol turnover, but not Gi/o). Our observations with these prominent commonalities may provide new insights into the phenotype and characteristics of AHH and the mechanisms by which the biased agonism of GPCRs operate." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Dual loss of regulator of G protein signaling 2 and 5 exacerbates ventricular myocyte arrhythmias and disrupts the fine-tuning of Gi/o signaling "Aims: Cardiac contractility, essential to maintaining proper cardiac output and circulation, is regulated by G protein-coupled receptor (GPCR) signaling. Previously, the absence of regulator of G protein signaling (RGS) 2 and 5, separately, was shown to cause G protein dysregulation, contributing to modest blood pressure elevation and exaggerated cardiac hypertrophic response to pressure-overload. Whether RGS2 and 5 redundantly control G protein signaling to maintain cardiovascular homeostasis is unknown. Here we examined how the dual absence of RGS2 and 5 (Rgs2/5 dbKO) affects blood pressure and cardiac structure and function." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Case Report of a Juvenile Patient with Autism Spectrum Disorder with a Novel Combination of Copy Number Variants in ADGRL3 (LPHN3) and Two Pseudogenes "We report the finding of two copy number variants (CNVs) in a 12-year-old boy presenting both with autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD). Clinical features included aggressive behavior, mood instability, suicidal statements, repetitive and restrictive behavior, sensitivity to noise, learning problems and dyslexia, though no intellectual disability was present. Using array-based comparative genomic hybridization (array-CGH), we identified two CNVs, both triplex duplications of 324 kb on 3p26.3, and 284 kb on 4q13.1, respectively. One of the CNVs is located on chromosome 4q13.1 in the region of the gene encoding for adhesion G protein-coupled receptor L3 (ADGRL3, former name: latrophilin-3, LPHN3), the other on chromosome 3p26.3 in the region of the two pseudogenes AC090043.1 and RPL23AP39. The patient described in the present study showed increased symptoms under methylphenidate treatment but responded positively to 3 mg per day of the atypical neuroleptic drug aripiprazole. To our knowledge, this is the first report of a CNV in the ADGRL3 gene and its first association with ASD in humans." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Identification of A2BAR as a potential target in colorectal cancer using novel fluorescent GPCR ligands "G-protein coupled receptors (GPCRs) have been largely targeted in a wide range of diseases, but few therapies have been directed against GPCRs in the field of cancer, partly because of the lack of effective target identification strategies. Here, using colorectal cancer (CRC) as a model, we explored the gene expression of a panel of GPCRs in tumor and stromal cells, identifying specific gene sets defining each cellular compartment. We selected the adenosine receptor 2B (A2BAR), specifically expressed in cancer cell lines compared with stromal cells, to explore the use of fluorescent ligands that can be used for target visualization. Fluorescent probes allowed semi-quantitative receptor mapping in living cells and validated the specific expression of A2BAR in CRC cell lines. As well, fluorescent ligands were effective at monitoring real-time A2BAR receptor labeling using live-imaging modalities, and displayed high efficiency when used to label complex 3D cellular systems such as tumor spheroids. Finally, we validated A2BAR as a potential pharmacological tool in CRC, using selective antagonists, finding a reduction in tumor cell proliferation. This proof-of-concept study suggests the use of fluorescent ligands for GPCR characterization through imaging, and as possible new tools used for target validation in drug screening methodologies." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Increased Anxiety-like Behaviors in Adgra1-/- Male But Not Female Mice are Attributable to Elevated Neuron Dendrite Density, Upregulated PSD95 Expression, and Abnormal Activation of the PI3K/AKT/GSK-3β and MEK/ERK Pathways "Adhesion G protein-coupled receptor A1 (ADGRA1) belongs to the G protein-coupled receptor (GPCR) family, and its physiological function remains largely unknown. We found that Adgra1 is highly and exclusively expressed in the brain, suggesting that Adgra1 may be involved in the regulation of neurological behaviors including anxiety, depression, learning and memory. To this end, we comprehensively analyzed the potential role of ADGRA1 in the neurobehaviors of mice by comparing Adgra1-/- and their wild-type (wt) littermates. We found that Adgra1-/- male but not female mice exhibited elevated anxiety levels in the open field, elevated plus maze, and light-dark box tests, with normal depression levels in the tail-suspension and forced-swim tests, and comparable learning and memory abilities in the Morris water maze, Y maze, fear condition, and step-down avoidance tests. Further studies showed that ADGRA1 deficiency resulted in higher dendritic branching complexity and spine density as evidenced by elevated expression levels of SYN and PSD95 in amygdalae of male mice. Finally, we found that PI3K/AKT/GSK-3β and MEK/ERK in amygdalae of Adgra1-deficient male mice were aberrantly activated when compared to wt male mice. Together, our findings reveal an important suppressive role of ADGRA1 in anxiety control and synaptic function by regulating the PI3K/AKT/GSK-3β and MEK/ERK pathways in amygdalae of male mice, implicating a potential, therapeutic application in novel anti-anxiety drug development." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Intermolecular Interactions in G Protein-Coupled Receptor Allosteric Sites at the Membrane Interface from Molecular Dynamics Simulations and Quantum Chemical Calculations "Allosteric modulators are called promising candidates in G protein-coupled receptor (GPCR) drug development by displaying subtype selectivity and more specific receptor modulation. Among the allosteric sites known to date, cavities at the receptor-lipid interface represent an uncharacteristic binding location that raises many questions about the ligand interactions and stability, the binding site structure, and how all of these are affected by lipid molecules. In this work, we analyze interactions in the allosteric sites of the PAR2, C5aR1, and GCGR receptors in three lipid compositions using molecular dynamics simulations. In addition, we performed quantum chemical calculations involving the symmetry-adapted perturbation theory (SAPT) and the natural population analysis to quantify the strength of intermolecular interactions. We show that besides classical hydrogen bonds, weak polar interactions such as O-HC, O-Br, and long-range electrostatics with the backbone amides contribute to the stability of allosteric modulators at the receptor-lipid interface. The allosteric cavities are detectable in various membrane compositions. The availability of polar atoms for interactions in such cavities can be assessed by water molecules from simulations. Although ligand-lipid interactions are weak, lipid tails play a role in ligand binding pose stability and the size of allosteric cavities. We discuss physicochemical aspects of ligand binding at the receptor-lipid interface and suggest a compound library enriched by weak donor groups for ligand search in such sites." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 "Adhesion G protein-coupled receptors (aGPCRs) are keys of many physiological events and attractive targets for various diseases. aGPCRs are also known to be capable of self-activation via an autoproteolysis process that removes the inhibitory GAIN domain on the extracellular side of receptor and releases a stalk peptide to bind and activate the transmembrane side of receptor. However, the detailed mechanism of aGPCR activation remains elusive. Here, we report the cryo-electron microscopy structures of GPR110 (ADGRF1), a member of aGPCR, in complex with Gq, Gs, Gi, G12 and G13. The structures reveal distinctive ligand engaging model and activation conformations of GPR110. The structures also unveil the rarely explored GPCR/G12 and GPCR/G13 engagements. A comparison of Gq, Gs, Gi, G12 and G13 engagements with GPR110 reveals details of G-protein engagement, including a dividing point at the far end of the alpha helix 5 (αH5) of Gα subunit that separates Gq/Gs engagements from Gi/G12/G13 engagements. This is also where Gq/Gs bind the receptor through both hydrophobic and polar interaction, while Gi/G12/G13 engage receptor mainly through hydrophobic interaction. We further provide physiological evidence of GPR110 activation via stalk peptide. Taken together, our study fills the missing information of GPCR/G-protein engagement and provides a framework for understanding aGPCR activation and GPR110 signaling." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 "Endogenous parathyroid hormone (PTH) and PTH-related peptide (PTHrP) bind to the parathyroid hormone receptor 1 (PTH1R) and activate the stimulatory G-protein (Gs) signaling pathway. Intriguingly, the two ligands have distinct signaling and physiological properties: PTH evokes prolonged Gs activation, whereas PTHrP evokes transient Gs activation with reduced bone-resorption effects. The distinct molecular actions are ascribed to the differences in ligand recognition and dissociation kinetics. Here, we report cryoelectron microscopic structures of six forms of the human PTH1R-Gs complex in the presence of PTH or PTHrP at resolutions of 2.8 -4.1 Å. A comparison of the PTH-bound and PTHrP-bound structures reveals distinct ligand-receptor interactions underlying the ligand affinity and selectivity. Furthermore, five distinct PTH-bound structures, combined with computational analyses, provide insights into the unique and complex process of ligand dissociation from the receptor and shed light on the distinct durations of signaling induced by PTH and PTHrP" Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Discovery and In Vivo Evaluation of ACT-660602: A Potent and Selective Antagonist of the Chemokine Receptor CXCR3 for Autoimmune Diseases "The chemokine receptor CXCR3 is a seven-transmembrane G-protein-coupled receptor (GPCR) involved in various pathologies, in particular autoimmune diseases. It is activated by the three chemokine ligands CXCL9, CXCL10, and CXCL11 and enables the recruitment of immune cell subsets leading to damage of inflamed tissues. Starting from a high-throughput screening hit, we describe the iterative optimization of a chemical series culminating in the discovery of the selective CXCR3 antagonist ACT-660602 (9j). The careful structural modifications during the lead optimization phase led to a compound with high biological potency in inhibiting cell migration together with improvements of the metabolic stability and hERG issue. In a LPS-induced lung inflammation model in mice, ACT-660602 led to significantly reduced recruitment of the CXCR3+ CD8+ T cell in the bronchoalveolar lavage compartment when administered orally at a dose of 30 mg/kg." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 "Visual phototransduction is the most extensively studied G protein-coupled receptor (GPCR) signaling pathway because of its quantifiable stimulus, non-redundancy of genes, and immense importance in vision. We summarize recent discoveries that have advanced our understanding of rod outer segment (ROS) morphology and the pathological basis of retinal diseases. We have combined recently published cryo-electron tomography (cryo-ET) data on the ROS with structural knowledge on individual proteins to define the precise spatial limitations under which phototransduction occurs. Although hypothetical, the reconstruction of the rod phototransduction system highlights the potential roles of phosphodiesterase 6 (PDE6) and guanylate cyclases (GCs) in maintaining the spacing between ROS discs, suggesting a plausible mechanism by which intrinsic optical signals are generated in the retina." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 "CXCR1 and CXCR2 chemokine receptors, mainly activated by interleukin 8 (IL-8 or CXCL8), are expressed in a variety of cells including, leukocytes, fibroblasts, endothelial cells, and smooth muscle cells. Numerous intracellular mediators are activated by these G protein-coupled receptors based on several factors, including the nature of the ligand, its concentration, and the binding sites with the receptor, levels of the receptor, cell type, and stimulatory environment. Much focus is currently being directed towards CXCR1/2 inhibitors, as these receptors primarily induce the chemotaxis of leukocytes, especially neutrophils, during inflammation, a key process in cardiovascular disease (CVD) progression. CXCR1/2 inhibitors show beneficial effects in various animal models of CVD. These effects include reducing the atherosclerotic plaque area, improving the serum lipid profile, attenuation of the damage following ischemia-reperfusion, the regulation of blood pressure, and the restriction of cardiac remodeling. Based on these encouraging results, testing CXCR1/2 inhibitors in clinical trials could be of a great importance to limit the inflammatory complications associated with CVDs." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 GPCR Agonist-to-Antagonist Conversion: Enabling the Design of Nucleoside Functional Switches for the A2A Adenosine Receptor "Modulators of the G protein-coupled A2A adenosine receptor (A2AAR) have been considered promising agents to treat Parkinson's disease, inflammation, cancer, and central nervous system disorders. Herein, we demonstrate that a thiophene modification at the C8 position in the common adenine scaffold converted an A2AAR agonist into an antagonist. We synthesized and characterized a novel A2AAR antagonist, 2 (LJ-4517), with Ki = 18.3 nM. X-ray crystallographic structures of 2 in complex with two thermostabilized A2AAR constructs were solved at 2.05 and 2.80 Å resolutions. In contrast to A2AAR agonists, which simultaneously interact with both Ser2777.42 and His2787.43, 2 only transiently contacts His2787.43, which can be direct or water-mediated. The n-hexynyl group of 2 extends into an A2AAR exosite. Structural analysis revealed that the introduced thiophene modification restricted receptor conformational rearrangements required for subsequent activation. This approach can expand the repertoire of adenosine receptor antagonists that can be designed based on available agonist scaffolds." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 "The canonical model for G protein-coupled receptors (GPCRs) activation assumes that stimulation of heterotrimeric G protein signaling upon ligand binding occurs solely at the cell surface and that duration of the stimulation is transient to prevent overstimulation. In this model, GPCR signaling is turned-off by receptor phosphorylation via GPCR kinases (GRKs) and subsequent recruitment of β-arrestins, resulting in receptor internalization into endosomes. Internalized receptors can then recycle back to the cell surface or be trafficked to lysosomes for degradation. However, over the last decade, this model has been extended by discovering that some internalized GPCRs continue to signal via G proteins from endosomes. This is the case for the parathyroid hormone (PTH) type 1 receptor (PTHR), which engages on sustained cAMP signaling from endosomes upon PTH stimulation. Accumulative evidence shows that the location of signaling has an impact on the physiological effects of GPCR signaling. This mini-review discusses recent insights into the mechanisms of PTHR endosomal signaling and its physiological impact." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 "Understanding the activation of G protein-coupled receptors (GPCRs) is of paramount importance to the field of cardiovascular medicine due to the critical physiological roles of these receptors and their prominence as drug targets. Although many cardiovascular GPCRs have been extensively studied as model receptors for decades, new complexities in their regulation continue to emerge. As a result, there is an ongoing need to develop novel approaches to monitor and to modulate GPCR activation. In less than a decade, nanobodies, or recombinant single-domain antibody fragments from camelids, have become indispensable tools for interrogating GPCRs both in purified systems and in living cells. Nanobodies have gained traction rapidly due to their biochemical tractability and their ability to recognize defined states of native proteins. Here, we review how nanobodies have been adopted to elucidate the structure, pharmacology, and signaling of cardiovascular GPCRs, resolving long-standing mysteries and revealing unexpected mechanisms. We also discuss how advancing technologies to discover nanobodies with tailored specificities may expand the impact of these tools for both basic science and therapeutic applications." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 High hedgehog signaling is transduced by a multikinase-dependent switch controlling the apico-basal distribution of the GPCR smoothened "The oncogenic G-protein-coupled receptor (GPCR) Smoothened (SMO) is a key transducer of the hedgehog (HH) morphogen, which plays an essential role in the patterning of epithelial structures. Here, we examine how HH controls SMO subcellular localization and activity in a polarized epithelium using the Drosophila wing imaginal disc as a model. We provide evidence that HH promotes the stabilization of SMO by switching its fate after endocytosis toward recycling. This effect involves the sequential and additive action of protein kinase A, casein kinase I, and the Fused (FU) kinase. Moreover, in the presence of very high levels of HH, the second effect of FU leads to the local enrichment of SMO in the most basal domain of the cell membrane. Together, these results link the morphogenetic effects of HH to the apico-basal distribution of SMO and provide a novel mechanism for the regulation of a GPCR." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 "Understanding the dopaminergic system is a priority in neurobiology and neuropharmacology. Dopamine receptors are involved in the modulation of fundamental physiological functions, and dysregulation of dopaminergic transmission is associated with major neurological disorders. However, the available tools to dissect the endogenous dopaminergic circuits have limited specificity, reversibility, resolution, or require genetic manipulation. Here, we introduce azodopa, a novel photoswitchable ligand that enables reversible spatiotemporal control of dopaminergic transmission. We demonstrate that azodopa activates D1-like receptors in vitro in a light-dependent manner. Moreover, it enables reversibly photocontrolling zebrafish motility on a timescale of seconds and allows separating the retinal component of dopaminergic neurotransmission. Azodopa increases the overall neural activity in the cortex of anesthetized mice and displays illumination-dependent activity in individual cells. Azodopa is the first photoswitchable dopamine agonist with demonstrated efficacy in wild-type animals and opens the way to remotely controlling dopaminergic neurotransmission for fundamental and therapeutic purposes." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Structural perspectives on the mechanism of signal activation, ligand selectivity and allosteric modulation in angiotensin receptors: IUPHAR Review 34 "Functional advances have guided our knowledge of physiological and fatal pathological mechanisms of the hormone angiotensin II (AngII) and its antagonists. Such studies revealed that tissue response to a given dose of the hormone or its antagonist depends on receptors that engage the ligand. Thus, we need to know much more about the structures of receptor-ligand complexes at high resolution. Recently, X-ray structures of both AngII receptors (AT1 and AT2 receptors) bound to peptide and non-peptide ligands have been elucidated, providing new opportunities to examine the dynamic fluxes in the 3D architecture of the receptors, as the basis of ligand selectivity, efficacy, and regulation of the molecular functions of the receptors. Constituent structural motifs cooperatively transform ligand selectivity into specific functions, thus conceptualizing the primacy of the 3D structure over individual motifs of receptors. This review covers the new data elucidating the structural dynamics of AngII receptors and how structural knowledge can be transformative in understanding the mechanisms underlying the physiology of AngII." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 "G protein-coupled receptors (GPCRs) are important drug targets characterized by a canonical seven transmembrane (TM) helix architecture. Recent advances in X-ray crystallography and cryo-EM have resulted in a wealth of GPCR structures that have been used in drug design and formed the basis for mechanistic activation hypotheses. Here, ensemble refinement (ER) of crystallographic structures is applied to explore the impact of binding of agonists and antagonist/inverse agonists to selected structures of cannabinoid receptor 1 (CB1R), β2 adrenergic receptor (β2 AR) and A2A adenosine receptor (A2A AR). " Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 "Arrestins interact with G protein-coupled receptors (GPCRs) to stop G protein activation and to initiate key signaling pathways. Recent structural studies shed light on the molecular mechanisms involved in GPCR-arrestin coupling, but whether this process is conserved among GPCRs is poorly understood. Here, we report the cryo-electron microscopy active structure of the wild-type arginine-vasopressin V2 receptor (V2R) in complex with β-arrestin1. It reveals an atypical position of β-arrestin1 compared to previously described GPCR-arrestin assemblies, associated with an original V2R/β-arrestin1 interface involving all receptor intracellular loops. Phosphorylated sites of the V2R carboxyl terminus are clearly identified and interact extensively with the β-arrestin1 N-lobe, in agreement with structural data obtained with chimeric or synthetic systems. Overall, these findings highlight a notable structural variability among GPCR-arrestin signaling complexes." Read more at the source #DrGPCR #GPCR #IndustryNews

October 2022 Recurrent hypoglycemia increases hepatic gluconeogenesis without affecting glycogen metabolism or systemic lipolysis in rat "Introduction: Recurrent hypoglycemia (RH) impairs secretion of counterregulatory hormones. Whether and how RH affects responses within metabolically important peripheral organs to counterregulatory hormones are poorly understood. Objective: To study the effects of RH on metabolic pathways associated with glucose counterregulation within liver, white adipose tissue and skeletal muscle. Methods: Using a widely adopted rodent model of 3-day recurrent hypoglycemia, we first checked expression of counterregulatory hormone G-protein coupled receptors (GPCRs), their inhibitory regulators and downstream enzymes catalyzing glycogen metabolism, gluconeogenesis and lipolysis by qPCR and western blot. Then, we examined epinephrine-induced phosphorylation of PKA substrates to validate adrenergic sensitivity in each organ. Next, we measured hepatic and skeletal glycogen content, degree of breakdown by epinephrine and abundance of phosphorylated glycogen phosphorylase under hypoglycemia and that of phosphorylated glycogen synthase during recovery to evaluate glycogen turnover. Further, we performed pyruvate and lactate tolerance tests to assess gluconeogenesis. Additionally, we measured circulating FFA and glycerol to check lipolysis. The abovementioned studies were repeated in streptozotocin-induced diabetic rat model. Finally, we conducted epinephrine tolerance test to investigate systemic glycemic excursions to counterregulatory hormones. Saline-injected rats served as controls." Read more at the source #DrGPCR #GPCR #IndustryNews