September 2022 Fentanyl activates ovarian cancer and alleviates chemotherapy-induced toxicity via opioid receptor-dependent activation of EGFR "Background Fentanyl is an opioid analgesic and is widely used in ovarian cancer patients for pain management. Although increasing evidence has suggested the direct role of fentanyl on cancer, little is known on the effect of fentanyl on ovarian cancer cells. Methods Proliferation, migration and apoptosis assays were performed in ovarian cancer cells after fentanyl treatment. Xenograft mouse model was generated to investigate the in vivo efficacy of fentanyl. Combination index was analyzed for the combination of fentanyl and chemotherapeutic drugs. Immunoblotting approach was used to analyze signaling involved in fentanyl’s action focusing on EGFR." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "Epithelial tube formation requires Rho1-dependent actomyosin contractility to generate the cellular forces that drive cell shape changes and rearrangement. Rho1 signaling is activated by G-protein-coupled receptor (GPCR) signaling at the cell surface. During Drosophila embryonic salivary gland (SG) invagination, the GPCR ligand Folded gastrulation (Fog) activates Rho1 signaling to drive apical constriction. The SG receptor that transduces the Fog signal into Rho1-dependent myosin activation has not been identified. Here, we reveal that the Smog GPCR transduces Fog signal to regulate Rho kinase accumulation and myosin activation in the medioapical region of cells to control apical constriction during SG invagination. We also report on unexpected Fog-independent roles for Smog in maintaining epithelial integrity and organizing cortical actin. Our data support a model wherein Smog regulates distinct myosin pools and actin cytoskeleton in a ligand-dependent manner during epithelial tube formation." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "In the Wnt-β-catenin pathway, Wnt binding to Frizzled (Fzd) and LRP5 or LRP6 (LRP5/6) co-receptors inhibits the degradation of the transcriptional coactivator β-catenin by recruiting the cytosolic effector Dishevelled (Dvl). Polymerization of Dvl at the plasma membrane recruits the β-catenin destruction complex, enabling the phosphorylation of LRP5/6, a key step in inhibiting β-catenin degradation. Using purified Fzd proteins reconstituted in lipid nanodiscs, we investigated the factors that promote the recruitment of Dvl to the plasma membrane. We found that the affinity of Fzd for Dvl was not affected by Wnt ligands, in contrast to other members of the GPCR superfamily for which the binding of extracellular ligands affects the affinity for downstream transducers. Instead, Fzd-Dvl binding was enhanced by increased concentration of the lipid PI(4,5)P2, which is generated by Dvl-associated lipid kinases in response to Wnt and which is required for LRP5/6 phosphorylation. Moreover, binding to Fzd did not promote Dvl DEP domain dimerization, which has been proposed to be required for signaling downstream of Fzd. Our findings suggest a positive feedback loop in which Wnt-stimulated local PI(4,5)P2 production enhances Dvl recruitment and further PI(4,5)P2 production to support Dvl polymerization, LRP5/6 phosphorylation, and β-catenin stabilization." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "Evaluation of stimulus salience is critical for any higher organism, as it allows for prioritizing of vital information, preparation of responses, and formation of valuable memory. The paraventricular nucleus of the thalamus (PVT) has recently been identified as an integrator of stimulus salience but the neurochemical basis and afferent input regarding salience signaling have remained elusive. Here we report that neuropeptide S (NPS) signaling in the PVT is necessary for stimulus salience encoding, including aversive, neutral and reinforcing sensory input. Taking advantage of a striking deficit of both NPS receptor (NPSR1) and NPS precursor knockout mice in fear extinction or novel object memory formation, we demonstrate that intra-PVT injections of NPS can rescue the phenotype in NPS precursor knockout mice by increasing the salience of otherwise low-intensity stimuli, while intra-PVT injections of NPSR1 antagonist in wild type mice partially replicates the knockout phenotype. The PVT appears to provide stimulus salience encoding in a dose- and NPS-dependent manner. PVT NPSR1 neurons recruit the nucleus accumbens shell and structures in the prefrontal cortex and amygdala, which were previously linked to the brain salience network. Overall, these results demonstrate that stimulus salience encoding is critically associated with NPS activity in the PVT." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "Introduction Protease activated receptors 1 (PAR1) and 4 (PAR4) agonists are used to study platelet activation. Data on platelet activation are extrapolated across experimental settings. C1-inhibitor (C1INH) is a protease inhibitor present in plasma but not in isolated platelet suspensions. Here we show that C1INH affects platelet activation through PAR1 and PAR4 agonists. Methods Platelets were isolated from healthy donor whole blood and then labeled with anti-CD62P and PAC1 antibodies. The platelet suspensions were exposed to PAR1 agonists SFLLRN, TFLLR and TFLLRN; PAR4 agonists AYPGKF and GYPGQV; ADP and thrombin. Flow-cytometric measurements were performed in 5, 10 and 15 min after activation." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "The GPR15 receptor is a G protein-coupled receptor (GPCR), which is activated by an endogenous peptide GPR15L(25-81) and a C-terminal peptide fragment GPR15L(71-81). GPR15 signals through the Gi/o pathway to decrease intracellular cyclic adenosine 3',5'-monophosphate (cAMP). However, the activation profiles of the GPR15 receptor within Gi/o subtypes have not been examined. Moreover, whether the receptor can also couple to Gs , Gq/11 and G12/13 is unclear. Here, GPR15L(25-81) and GPR15L(71-81) are used as pharmacological tool compounds to delineate the GPR15 receptor-mediated Gα protein signalling using a G protein activation assay and second messenger assay conducted on living cells. The results show that the GPR15 receptor preferentially couples to Gi/o rather than other pathways in both assays. Within the Gi/o family, the GPR15 receptor activates all the subtypes (Gi1 , Gi2 , Gi3 , GoA , GoB and Gz ). The Emax and activation rates of Gi1, Gi2 , Gi3, GoA and GoB are similar, whilst the Emax of Gz is smaller and the activation rate is significantly slower. The potencies of both peptides toward each Gi/o subtype have been determined. Furthermore, the GPR15 receptor signals through Gi/o to inhibit cAMP accumulation, which could be blocked by the application of the Gi/o inhibitor pertussis toxin." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 " Background and purpose: The interaction of arrestins with G-protein coupled receptors (GPCRs) desensitizes agonist-dependent receptor responses and often leads to receptor internalization. GPCRs that internalize without arrestin have been classified as "class A" GPCRs whereas "class B" GPCRs co-internalize with arrestin into endosomes. The interaction of arrestins with GPCRs requires both agonist activation and receptor phosphorylation. Here, we ask the question whether agonists with very slow off-rates can cause the formation of particularly stable receptor-arrestin complexes." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 Lack of Oestrogen Receptor Expression in Breast Cancer Cells Does Not Correlate with Kisspeptin Signalling and Migration "Kisspeptin is an anti-metastatic mediator in many cancer types, acting through its receptor, KISS1R. However, controversy remains regarding its role in breast cancer since both pro- and anti-metastatic roles have been ascribed to it. In KISS1R overexpressing triple-negative breast cancer (TNBC) cells, stimulation has been associated with increased invasion and MMP-9 expression, leading to the suggestion that hormone receptor status determines the metastatic effects of kisspeptin. To assess the veracity of this claim, we compared endogenous KISS1R signalling and physiological output in the hormone receptor-negative MDA-MB-231 and BT-20 cell lines after KP-10 (shortest active kisspeptin peptide) stimulation. MDA-MB-231 cells are metastatic when implanted in mice while BT-20 are not and remain epithelial-like. We show that both cell lines express KISS1R mRNA and respond to KP-10 by elevating calcium mobilisation. However, KP-10 stimulation induced migration of MDA-MB-231, but not BT-20 cells, in a calcium-dependent manner. Moreover, only BT-20 cells responded to KP-10 by increasing ERK phosphorylation in a β-arrestin-dependent manner. Interestingly, both cell lines displayed different complements of β-arrestin 1 and 2 expression. Overall, our data shows that, in TNBC, it is not universally true that kisspeptin/KISS1R stimulate migration or pro-metastatic behaviour, as divergent responses were observed in the two TNBC lines tested. Whether this divergence is related to the observed differences in β-arrestin complements warrants further investigation and may enable further stratification of the ability of kisspeptin to influence breast tumour behaviour." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "Background G protein-coupled receptor (GPCR) is the most targeted protein family by the FDA-approved drugs. GPCR-kinase 3 (GRK3) is critical for GPCR signaling. Our genomic analysis showed that GRK3 expression correlated with poor prognosis of gastric adenocarcinoma (GAC) patients. However, GRK3’s functions and clinical utility in GAC progression and metastases are unknown. Methods We studied GRK3 expression in normal, primary, and metastatic GAC tissues. We identified a novel GRK3 inhibitor, LD2, through a chemical-library screen. Through genetic and pharmacologic modulations of GRK3, a series of functional and molecular studies were performed in vitro and in vivo . Impact of GRK3 on YAP1 and its targets was determined." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "The complement fragment C5a is one of the most potent proinflammatory glycoproteins liberated by the activation of the biochemical cascade of the complement system. C5a is established to interact with a set of genomically related transmembrane receptors, like C5aR1 (CD88, C5aR) and C5aR2 (GPR77, C5L2) with comparable affinity. The C5aR1 is a classical G-protein-coupled receptor (GPCR), whereas C5aR2 is a nonclassical GPCR that tailors immune cell activity potentially through β-arrestins rather than G-proteins. Currently, the exact function of the C5aR2 is actively debated in the context of C5aR1, even though both C5aR1 and C5aR2 are coexpressed on myriads of tissues. The functional relevance of C5aR2 appears to be context-dependent compared to the C5aR1, which has received enormous attention for its role in both acute and chronic inflammatory diseases. In addition, the structure of C5aR2 and its interaction specificity toward C5a is not structurally elucidated in the literature so far. The current study has attempted to close the gap by generating highly refined model structures of C5aR2, respectively in free (inactive), complexed to C-terminal peptide of C5a (meta-active) and the C5a (active), embedded to a model palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer. The computational modeling and the 1.5-μs molecular dynamics data presented in the current study are expected to further enrich the understanding of C5a-C5aR2 interaction compared to C5a-C5aR1, which will surely help in elaborating the currently debated biological function of C5aR2 better in the foreseeable future." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "Chemerin is the product of the RARRES2 gene which is secreted as a precursor of 143 amino acids. That precursor is inactive, but proteases from the coagulation and fibrinolytic cascades, as well as from inflammatory reactions, process the C-terminus of chemerin to first activate it and then subsequently inactivate it. Chemerin can signal via two G protein-coupled receptors, chem1 and chem2, as well as be bound to a third non-signaling receptor, CCRL2. Chemerin is produced by the liver and secreted into the circulation as a precursor, but it is also expressed in some tissues where it can be activated locally. This review discusses the specific tissue expression of the components of the chemerin system, and the role of different proteases in regulating the activation and inactivation of chemerin. Methods of identifying and determining the levels of different chemerin forms in both mass and activity assays are reviewed. The levels of chemerin in circulation are correlated with certain disease conditions, such as patients with obesity or diabetes, leading to the possibility of using chemerin as a biomarker." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 Microbial Metabolites Orchestrate a Distinct Multi-Tiered Regulatory Network in the Intestinal Epithelium That Directs P-Glycoprotein Expression "P-glycoprotein (P-gp) is a key component of the intestinal epithelium playing a pivotal role in removal of toxins and efflux of endocannabinoids to prevent excessive inflammation and sustain homeostasis. Recent studies revealed butyrate and secondary bile acids, produced by the intestinal microbiome, potentiate the induction of functional P-gp expression. We now aim to determine the molecular mechanism by which this functional microbiome output regulates P-gp. RNA sequencing of intestinal epithelial cells responding to butyrate and secondary bile acids in combination discovered a unique transcriptional program involving multiple pathways that converge on P-gp induction. Using shRNA knockdown and CRISPR/Cas9 knockout cell lines, as well as mouse models, we confirmed the RNA sequencing findings and discovered a role for intestinal HNF4α in P-gp regulation. These findings shed light on a sophisticated signaling network directed by intestinal microbial metabolites that orchestrate P-gp expression and highlight unappreciated connections between multiple pathways linked to colonic health." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 Endothelin-1 Stimulates PAI-1 Protein Expression via Dual Transactivation Pathway Dependent ROCK and Phosphorylation of Smad2L "In addition to the carboxy region, Smad2 transcription factor can be phosphorylated in the linker region aswell. Phosphorylation of Smad2 linker region (Smad2L) promotes the expression of plasminogen activator inhibitor type1 (PAI-1) which leads to cardiovascular disorders such as atherosclerosis. The purpose of this study was to evaluate the role of dual transactivation of EGF and TGF-β receptors in phosphorylation of Smad2L and protein expression of PAI-1 induced by endothelin-1 (ET-1) in bovine aortic endothelial cells (BAECs). In addition, as an intermediary of G protein-coupled receptor (GPCR) signaling, the functions of ROCK and PLC were investigated in dual transactivation pathways.Materials and Methods: The experimental study is an in vitro study performed on BAECs. Proteins were investigatedby western blotting using protein-specific antibodies against phospho-Smad2 linker region residues (Ser245/250/255),phospho-Smad2 carboxy residues (465/467), ERK1/(Thr202/Thr204), and PAI-1.Results: TGF (2 ng/ml), EGF (100 ng/ml) and ET-1 (100 nM) induced the phosphorylation of Smad2L. This response wasblocked in the presence of AG1478 (EGFR antagonists), SB431542 (TGFR inhibitor), and Y27632 (Rho-associated protein kinase (ROCK antagonist). Moreover, ET-1-increased protein expression of PAI-1 was decreased in the presence of bosentan (ET receptor inhibitor), AG1478, SB431542, and Y27632.Conclusion: The results indicated that ET-1 increases the phosphorylation of Smad2L and protein expression of PAI-1via induced the transactivation pathways of EGFR and TGFR. This study is the first attempt to scrutinize the significant role of ROCK in the protein expression of PAI-1." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 Structure of the human galanin receptor 2 bound to galanin and Gq reveals the basis of ligand specificity and how binding affects the G-protein interface "Galanin is a neuropeptide expressed in the central and peripheral nervous systems, where it regulates various processes including neuroendocrine release, cognition, and nerve regeneration. Three G-protein coupled receptors (GPCRs) for galanin have been discovered, which is the focus of efforts to treat diseases including Alzheimer’s disease, anxiety, and addiction. To understand the basis of the ligand preferences of the receptors and to assist structure-based drug design, we used cryo-electron microscopy (cryo-EM) to solve the molecular structure of GALR2 bound to galanin and a cognate heterotrimeric G-protein, providing a molecular view of the neuropeptide binding site. Mutant proteins were assayed to help reveal the basis of ligand specificity, and structural comparison between the activated GALR2 and inactive hβ2AR was used to relate galanin binding to the movements of transmembrane (TM) helices and the G-protein interface." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 Regulator of G Protein Signaling 20 Correlates with Long Intergenic Non-Coding RNA (lincRNAs) Harboring Oncogenic Potential and Is Markedly Upregulated in Hepatocellular Carcinoma "Hepatocellular carcinoma (HCC) is at the forefront of the global cancer burden, and biomarkers for HCC are constantly being sought. Interestingly, RGS (Regulators of G protein signaling) proteins, which negatively regulate GPCR signaling, have been associated with various cancers, with some members of the RGS family being associated with liver cancer as well. Considering this, we investigated the role of RGS20 as a potential prognostic marker in 28 different cancer types with special emphasis on HCC. By using the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) data, our analysis revealed that (a) RGS20 was strongly upregulated in tumor tissue compared with adjacent normal tissue of HCC patients; (b) RGS20 was strongly associated with some important clinical parameters such as alpha-fetoprotein and tumor grade in the HCC patients; (c) besides HCC ( p < 0.001), RGS20 was found to be an important factor for survival in four other cancers (clear renal cell carcinoma: p < 0.001, lung adenocarcinoma: p = 0.004, mesothelioma: p = 0.039, ovarian serous cystadenocarcinoma: p = 0.048); (d) RGS20 was found to be significantly associated with some tumor-related signaling pathways and long intergenic non-coding RNAs (lincRNAs: LINC00511, PVT1, MIR4435-2HG, BCYRN1, and MAPKAPK5-AS1) that exhibit oncogenic potential. Taken together, we showed that RGS20 correlates with a few HCC-associated lincRNAs harboring oncogenic potential and is markedly upregulated in HCC patients. Our analysis further supports the putative function of RGS proteins, particularly RGS20, in cancer." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "For decades, glioblastoma multiforme (GBM), a type of the most lethal brain tumor, has remained a formidable challenge in terms of its treatment. Recently, many novel discoveries have underlined the regulatory roles of neurotransmitters in the microenvironment both physiologically and pathologically. By targeting the receptors synaptically or non-synaptically, neurotransmitters activate multiple signaling pathways. Significantly, many ligands acting on neurotransmitter receptors have shown great potential for inhibiting GBM growth and development, requiring further research. Here, we provide an overview of the most novel advances concerning the role of neurotransmitters in the normal neural and the GBM microenvironments, and discuss potential targeted drugs used for GBM treatment." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 Ginsenoside Rg5 allosterically interacts with P2RY12 and ameliorates deep venous thrombosis by counteracting neutrophil NETosis and inflammatory response "Deep venous thrombosis (DVT) highly occurs in patients with severe COVID-19 and probably accounted for their high mortality. DVT formation is a time-dependent inflammatory process in which NETosis plays an important role. However, whether ginsenoside Rg5 from species of Panax genus could alleviate DVT and its underlying mechanism has not been elucidated." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 Expression pattern and clinical significance of beta 2-adrenergic receptor in oral squamous cell carcinoma: an emerging prognostic indicator and future therapeutic target " Purpose: Beta 2-Adrenergic Receptor (β2-AR) is significantly overexpressed in various types of malignancies, which is associated with the worst prognosis. However, the role of β2-AR in oral cancer is not well identified. The present study aimed at investigating the β2-AR gene expression and its significance in relation with the clinicopathological features and overall survival of oral squamous cell carcinoma (OSCC) patients. Methods: Immunohistochemistry, western blot and quantitative real-time PCR techniques were used to analyze β2-AR protein and mRNA levels in a total of 65 histopathologically confirmed OSCC tissues (case group) and 65 normal tissues (control group) from the oral cavity." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 Cell-Type-Specific Effects of the Ovarian Cancer G-Protein Coupled Receptor (OGR1) on Inflammation and Fibrosis; Potential Implications for Idiopathic Pulmonary Fibrosis "Idiopathic pulmonary fibrosis (IPF) is a disease characterized by irreversible lung scarring. The pathophysiology is not fully understood, but the working hypothesis postulates that a combination of epithelial injury and myofibroblast differentiation drives progressive pulmonary fibrosis. We previously demonstrated that a reduction in extracellular pH activates latent TGF-β1, and that TGF-β1 then drives its own activation, creating a feed-forward mechanism that propagates myofibroblast differentiation. Given the important roles of extracellular pH in the progression of pulmonary fibrosis, we sought to identify whether pH mediates other cellular phenotypes independent of TGF-β1. Proton-sensing G-protein coupled receptors are activated by acidic environments, but their role in fibrosis has not been studied. Here, we report that the Ovarian Cancer G-Protein Coupled Receptor1 (OGR1 or GPR68) has dual roles in both promoting and mitigating pulmonary fibrosis. We demonstrate that OGR1 protein expression is significantly reduced in lung tissue from patients with IPF and that TGF-β1 decreases OGR1 expression. In fibroblasts, OGR1 inhibits myofibroblast differentiation and does not contribute to inflammation. However, in epithelial cells, OGR1 promotes epithelial to mesenchymal transition (EMT) and inflammation. We then demonstrate that sub-cellular localization and alternative signaling pathways may be responsible for the differential effect of OGR1 in each cell type. Our results suggest that strategies to selectively target OGR1 expression may represent a novel therapeutic strategy for pulmonary fibrosis." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "Metabotropic γ-aminobutyric acid receptor (GABABR), a class C G protein-coupled receptor (GPCR) heterodimer, plays a crucial role in the central nervous system. Cryo-electron microscopy studies revealed a drastic conformational change upon activation and a unique G protein (GP) binding mode. However, little is known about the mechanism for GP coupling and activation for class C GPCRs. Here, we use molecular metadynamics computations to predict the mechanism by which the inactive GP induces conformational changes in the GABABR transmembrane domain (TMD) to form an intermediate pre-activated state. We find that the inactive GP first interacts with TM3, which further leads to the TMD rearrangement and deeper insertion of the α5 helix that causes the Gα subunit to open, releasing GDP, and forming the experimentally observed activated structure. This mechanism provides fresh insights into the mechanistic details of class C GPCRs activation expected to be useful for designing selective agonists and antagonists." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "The diamondback moth (Plutella xylostella) is one of the most destructive lepidopteran pests of cruciferous vegetables, and insights into regulation of its physiological processes contribute towards the development of new pesticides against it. Thus, we investigated the regulatory functions of its β-adrenergic-like octopamine receptor (PxOctβ3). The open reading frame (ORF) of PxOctβ3 was phylogenetically analyzed, and the levels of expression of the receptor mRNA were determined. This ORF was also cloned and expressed in HEK-293 cells. A series of octopamine receptor agonists and antagonists were tested against PxOctβ3. We showed that the receptor is a member of the Octβ3 protein family, and an analysis using quantitative PCR showed that it was expressed at all developmental stages of P. xylostella. Octopamine activated PxOctβ3, resulting in increased levels of intracellular cAMP. Furthermore, the agonists naphazoline, clonidine, 2-phenethylamine, and amitraz activated the PxOctβ3 receptor, and naphazoline was the most effective. Only metoclopramide and mianserin had significant antagonistic effects on PxOctβ3, whereas yohimbine, phentolamine, and chlorpromazine lacked obvious antagonistic effects. The injection of double-stranded RNA in an RNA interference assay indicated that PxOctβ3 regulates development in P. xylostella. This study demonstrated the pharmacological properties and functions of PxOctβ3 in P. xylostella, thus, providing a theoretical basis for the design of pesticides that target octopamine receptors." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "Platelets are well characterized for their indispensable role in primary hemostasis to control hemorrhage. Research over the past years has provided a substantial body of evidence demonstrating that platelets also participate in host innate immunity. The surface expression of pattern recognition receptors, such as TLR2 and TLR4, provides platelets with the ability to sense bacterial products in their environment. Platelet α-granules contain microbicidal proteins, chemokines and growth factors, which upon release may directly engage pathogens and/or contribute to inflammatory signaling. Additionally, platelet interactions with neutrophils enhance neutrophil activation and are often crucial to induce a sufficient immune response. In particular, platelets can activate neutrophils to form neutrophil extracellular traps (NETs). This specific neutrophil effector function is characterized by neutrophils expelling chromatin fibres decorated with histones and antimicrobial proteins into the extracellular space where they serve to trap and kill pathogens. Until now, the mechanisms and signaling pathways between platelets and neutrophils inducing NET formation are still not fully characterized. NETs were also detected in thrombotic lesions in several disease backgrounds, pointing towards a role as an interface between neutrophils, platelets and thrombosis, also known as immunothrombosis. The negatively charged DNA within NETs provides a procoagulant surface, and in particular NET-derived proteins may directly activate platelets. In light of the current COVID-19 pandemic, the topic of immunothrombosis has become more relevant than ever, as a majority of COVID-19 patients display thrombi in the lung capillaries and other vascular beds. Furthermore, NETs can be found in the lung and other tissues and are associated with an increased mortality. Here, virus infiltration may lead to a cytokine storm that potently activates neutrophils and leads to massive neutrophil infiltration into the lung and NET formation. The resulting NETs presumably activate platelets and coagulation factors, further contributing to the subsequent emergence of microthrombi in pulmonary capillaries. In this review, we will discuss the interplay between platelets and NETs and the potential of this alliance to influence the course of inflammatory diseases. A better understanding of the underlying molecular mechanisms and the identification of treatment targets is of utmost importance to increase patients’ survival and improve the clinical outcome." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "The activation of phospholipase C (PLC) is thought to have a key role in the cardiomyocyte response to several different hypertrophic agents such as norepinephrine, angiotensin II and endothelin-1. PLC activity results in the generation of diacylglycerol and inositol trisphosphate, which are downstream signal transducers for the expression of fetal genes, increased protein synthesis, and subsequent cardiomyocyte growth. In this article, we describe the signal transduction elements that regulate PLC gene expression. The discussion is focused on the norepinephrine- α1-adrenoceptor signaling pathway and downstream signaling processes that mediate an upregulation of PLC isozyme gene expression. Evidence is also indicated to demonstrate that PLC activities self-regulate the expression of PLC isozymes with the suggestion that PLC activities may be part of a coordinated signaling process for the perpetuation of cardiac hypertrophy. Accordingly, from the information provided, it is plausible that specific PLC isozymes could be targeted for the mitigation of cardiac hypertrophy." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 GPCR/endocytosis/ERK signaling/S2R is involved in the regulation of the internalization, mitochondria-targeting and -activating properties of human salivary histatin 1 "Human salivary histatin 1 (Hst1) exhibits a series of cell-activating properties, such as promoting cell spreading, migration, and metabolic activity. We recently have shown that fluorescently labeled Hst1 (F-Hst1) targets and activates mitochondria, presenting an important molecular mechanism. However, its regulating signaling pathways remain to be elucidated. We investigated the influence of specific inhibitors of G protein-coupled receptors (GPCR), endocytosis pathways, extracellular signal-regulated kinases 1/2 (ERK1/2) signaling, p38 signaling, mitochondrial respiration and Na+/K+-ATPase activity on the uptake, mitochondria-targeting and -activating properties of F-Hst1. We performed a siRNA knockdown (KD) to assess the effect of Sigma-2 receptor (S2R) /Transmembrane Protein 97 (TMEM97)—a recently identified target protein of Hst1. We also adopted live cell imaging to monitor the whole intracellular trafficking process of F-Hst1. Our results showed that the inhibition of cellular respiration hindered the internalization of F-Hst1. The inhibitors of GPCR, ERK1/2, phagocytosis, and clathrin-mediated endocytosis (CME) as well as siRNA KD of S2R/TMEM97 significantly reduced the uptake, which was accompanied by the nullification of the promoting effect of F-Hst1 on cell metabolic activity. Only the inhibitor of CME and KD of S2R/TMEM97 significantly compromised the mitochondria-targeting of Hst1. We further showed the intracellular trafficking and targeting process of F-Hst1, in which early endosome plays an important role. Overall, phagocytosis, CME, GPCR, ERK signaling, and S2R/TMEM97 are involved in the internalization of Hst1, while only CME and S2R/TMEM97 are critical for its subcellular targeting. The inhibition of either internalization or mitochondria-targeting of Hst1 could significantly compromise its mitochondria-activating property." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "Given the promising clinical value of allosteric modulators of G protein-coupled-receptors (GPCRs), mechanistic understanding of how these modulators alter GPCR function is of significance. Here, we report the crystallographic and cryo-electron microscopy structures of the cannabinoid receptor CB1 bound to the positive allosteric modulator (PAM) ZCZ011. These structures show that ZCZ011 binds to an extrahelical site in the transmembrane 2 (TM2)-TM3-TM4 surface. Through (un)biased molecular dynamics simulations and mutagenesis experiments, we show that TM2 rearrangement is critical for the propagation of allosteric signals. ZCZ011 exerts a PAM effect by promoting TM2 rearrangement in favor of receptor activation and increasing the population of receptors that adopt an active conformation. In contrast, ORG27569, a negative allosteric modulator (NAM) of CB1, also binds to the TM2-TM3-TM4 surface and exerts a NAM effect by impeding the TM2 rearrangement. Our findings fill a gap in the understanding of CB1 allosteric regulation and could guide the rational design of CB1 allosteric modulators." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) lipids have been shown to stabilize an active conformation of class A G-protein coupled receptors (GPCRs) through a conserved binding site, not present in class B GPCRs. For class B GPCRs, previous molecular dynamics (MD) simulation studies have shown PI(4,5)P2 interacting with the Glucagon receptor (GCGR), which constitutes an important target for diabetes and obesity therapeutics. In this work, we applied MD simulations supported by native mass spectrometry (nMS) to study lipid interactions with GCGR. We demonstrate how tail composition plays a role in modulating the binding of PI(4,5)P2 lipids to GCGR. Specifically, we find the PI(4,5)P2 lipids to have a higher affinity toward the inactive conformation of GCGR. Interestingly, we find that in contrast to class A GPCRs, PI(4,5)P2 appear to stabilize the inactive conformation of GCGR through a binding site conserved across class B GPCRs but absent in class A GPCRs. This suggests differences in the regulatory function of PI(4,5)P2 between class A and class B GPCRs." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "Heterotrimeric G-protein transducin, Gt, is a key signal transducer and amplifier in retinal rod and cone photoreceptor cells. Despite similar subunit composition, close amino acid identity, and identical posttranslational farnesylation of their Gγ subunits, rods and cones rely on unique Gγ1 ( Gngt1 ) and Gγc ( Gngt2 ) isoforms, respectively. The only other farnesylated G-protein γ-subunit, Gγ11 ( Gng11 ), is expressed in multiple tissues but not retina. To determine whether Gγ1 regulates uniquely rod phototransduction, we generated transgenic rods expressing Gγ1, Gγc, or Gγ11 in Gγ1-deficient mice and analyzed their properties. Immunohistochemistry and Western blotting demonstrated the robust expression of each transgenic Gγ in rod cells and restoration of Gαt1 expression, which is greatly reduced in Gγ1-deficient rods. Electroretinography showed restoration of visual function in all three transgenic Gγ1-deficient lines. Recordings from individual transgenic rods showed that photosensitivity impaired in Gγ1-deficient rods was also fully restored. In all dark-adapted transgenic lines, Gαt1 was targeted to the outer segments, reversing its diffuse localization found in Gγ1-deficient rods. Bright illumination triggered Gαt1 translocation from the rod outer to inner segments in all three transgenic strains. However, Gαt1 translocation in Gγ11 transgenic mice occurred at significantly dimmer background light. Consistent with this, transretinal ERG recordings revealed gradual response recovery in moderate background illumination in Gγ11 transgenic mice but not in Gγ1 controls. Thus, while farnesylated Gγ subunits are functionally active and largely interchangeable in supporting rod phototransduction, replacement of retina-specific Gγ isoforms by the ubiquitous Gγ11 affects the ability of rods to adapt to background light." Read more at the source #DrGPCR #GPCR #IndustryNews

September 2022 "GPCR signaling and function depend on their associated proteins and subcellular locations. Besides G-proteins and β-arrestins, 14-3-3 proteins participate in GPCR trafficking and signaling, and they connect a large number of diverse proteins to form signaling networks. Multiple 14-3-3 isoforms exist, and a GPCR can differentially interact with different 14-3-3 isoforms in response to agonist treatment. We found that some agonist-induced GPCR/14-3-3 signal intensities can rapidly decrease. We confirmed that this phenomenon of rapidly decreasing agonist-induced GPCR/14-3-3 signal intensity could also be paralleled with GPCR/β-arrestin-2 signals, indicating diminished levels of GPCR/signal adaptor complexes during endocytosis. The temporal signals could implicate either GPCR/14-3-3 complex dissociation or the complex undergoing a degradation process. Furthermore, we found that certain GPCR ligands can regulate GPCR/14-3-3 signals temporally, suggesting a new approach for GPCR drug development by modulating GPCR/14-3-3 signals temporally." Read more at the source #DrGPCR #GPCR #IndustryNews