Showing papers on "Receptor published in 2016"
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TL;DR: Co-inhibitory receptors, such as CTLA-4 and PD-1, have an important role in regulating T cell responses and have proven to be effective targets in the setting of chronic diseases where constitutive co- inhibitory receptor expression on T cells dampens effector T-cell responses.
1,392 citations
01 Jan 2016
TL;DR: The phorbol diester receptor present in the par- ticulate fraction of rat brain was solubilized by divalent ion che- lation in the absence of detergents as mentioned in this paper.
Abstract: The phorbol diester receptor present in the par- ticulate fraction of rat brain was solubilized by divalent ion che- lation in the absence of detergents. The soluble receptor was par- tially purified by (NH4)2SO4 precipitation, DEAE-cellulose, and gel filtration chromatography. The purified receptor required exogenous phospholipid for activity and displayed a Kd of 7 nM for (3H)phorbol 12,13-dibutyrate. Biologically active phorbol analogs inhibited binding, whereas inactive analogs did not. The Ca2+- dependent, phospholipid-sensitive protein kinase C copurified with the phorbol receptor. Purified protein kinase C was activated directly by phorbol 12-myristate 13-acetate in the presence of phospholipid.
917 citations
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TL;DR: Using genetic gain- and loss-of-function approaches, it is found that capture of IL-2 was dispensable for the control of CD4+ T cells but was important for limiting the activation of CD8 + T cells, and thatIL-2R-dependent activation of the transcription factor STAT5 had an essential role in the suppressor function of Treg cells separable from signaling via the T cell antigen receptor.
Abstract: Regulatory T cells (Treg cells), which have abundant expression of the interleukin 2 receptor (IL-2R), are reliant on IL-2 produced by activated T cells. This feature indicates a key role for a simple network based on the consumption of IL-2 by Treg cells in their suppressor function. However, congenital deficiency in IL-2R results in reduced expression of the Treg cell lineage-specification factor Foxp3, which has confounded experimental efforts to understand the role of IL-2R expression and signaling in the suppressor function of Treg cells. Using genetic gain- and loss-of-function approaches, we found that capture of IL-2 was dispensable for the control of CD4+ T cells but was important for limiting the activation of CD8+ T cells, and that IL-2R-dependent activation of the transcription factor STAT5 had an essential role in the suppressor function of Treg cells separable from signaling via the T cell antigen receptor.
520 citations
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TL;DR: A specific marker of human PMN-MDSC associated with ER stress and lipid metabolism is identified, which provides new insights into the biology and potential therapeutic targeting of these cells.
Abstract: Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) are important regulators of immune responses in cancer and have been directly implicated in promotion of tumor progression. However, the heterogeneity of these cells and lack of distinct markers hampers the progress in understanding of the biology and clinical importance of these cells. Using partial enrichment of PMN-MDSC with gradient centrifugation we determined that low density PMN-MDSC and high density neutrophils from the same cancer patients had a distinct gene profile. Most prominent changes were observed in the expression of genes associated with endoplasmic reticulum (ER) stress. Surprisingly, low-density lipoprotein (LDL) was one of the most increased regulators and its receptor oxidized LDL receptor 1 OLR1 was one of the most overexpressed genes in PMN-MDSC. Lectin-type oxidized LDL receptor 1 (LOX-1) encoded by OLR1 was practically undetectable in neutrophils in peripheral blood of healthy donors, whereas 5-15% of total neutrophils in cancer patients and 15-50% of neutrophils in tumor tissues were LOX-1+. In contrast to their LOX-1- counterparts, LOX-1+ neutrophils had gene signature, potent immune suppressive activity, up-regulation of ER stress, and other biochemical characteristics of PMN-MDSC. Moreover, induction of ER stress in neutrophils from healthy donors up-regulated LOX-1 expression and converted these cells to suppressive PMN-MDSC. Thus, we identified a specific marker of human PMN-MDSC associated with ER stress and lipid metabolism, which provides new insight to the biology and potential therapeutic targeting of these cells.
514 citations
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TL;DR: This review introduces some basic components of the TGF-β signaling pathways and their actions, and discusses posttranslational modifications and modulatory partners that modify the outcome of the signaling and contribute to its context-dependence, including small noncoding RNAs.
Abstract: Transforming growth factor β (TGF-β) and related growth factors are secreted pleiotropic factors that play critical roles in embryogenesis and adult tissue homeostasis by regulating cell proliferation, differentiation, death, and migration. The TGF-β family members signal via heteromeric complexes of type I and type II receptors, which activate members of the Smad family of signal transducers. The main attribute of the TGF-β signaling pathway is context-dependence. Depending on the concentration and type of ligand, target tissue, and developmental stage, TGF-β family members transmit distinct signals. Deregulation of TGF-β signaling contributes to developmental defects and human diseases. More than a decade of studies have revealed the framework by which TGF-βs encode a context-dependent signal, which includes various positive and negative modifiers of the principal elements of the signaling pathway, the receptors, and the Smad proteins. In this review, we first introduce some basic components of the TGF-β signaling pathways and their actions, and then discuss posttranslational modifications and modulatory partners that modify the outcome of the signaling and contribute to its context-dependence, including small noncoding RNAs.
513 citations
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TL;DR: It is shown that synNotch receptors can be used to sculpt custom response programs in primary T cells: they can drive a la carte cytokine secretion profiles, biased T cell differentiation, and local delivery of non-native therapeutic payloads in response to antigen.
454 citations
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TL;DR: Transforming growth factor β (TGF-β) family members signal via heterotetrameric complexes of type I and type II dual specificity kinase receptors that are controlled by posttranslational modifications, such as phosphorylation, ubiquitylation, sumoylation, and neddylation.
Abstract: Transforming growth factor beta (TGF-beta) family members signal via heterotetrameric complexes of type I and type II dual specificity kinase receptors. The activation and stability of the receptor ...
432 citations
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TL;DR: An ionic checkpoint that blocks T cell function in tumours is uncovered and potential new strategies for cancer immunotherapy are identified, including boosting potassium efflux in tumour-specific T cells by overexpressing the potassium channel Kv1.3.
Abstract: Tumours progress despite being infiltrated by tumour-specific effector T cells. Tumours contain areas of cellular necrosis, which are associated with poor survival in a variety of cancers. Here, we show that necrosis releases intracellular potassium ions into the extracellular fluid of mouse and human tumours, causing profound suppression of T cell effector function. Elevation of the extracellular potassium concentration ([K+]e) impairs T cell receptor (TCR)-driven Akt-mTOR phosphorylation and effector programmes. Potassium-mediated suppression of Akt-mTOR signalling and T cell function is dependent upon the activity of the serine/threonine phosphatase PP2A. Although the suppressive effect mediated by elevated [K+]e is independent of changes in plasma membrane potential (Vm), it requires an increase in intracellular potassium ([K+]i). Accordingly, augmenting potassium efflux in tumour-specific T cells by overexpressing the potassium channel Kv1.3 lowers [K+]i and improves effector functions in vitro and in vivo and enhances tumour clearance and survival in melanoma-bearing mice. These results uncover an ionic checkpoint that blocks T cell function in tumours and identify potential new strategies for cancer immunotherapy.
431 citations
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TL;DR: It is reported that encounters with microbial products and self-encoded oxidized phospholipids (oxPAPC) induce an enhanced DC activation state, which is called “hyperactive” and induce potent adaptive immune responses and are elicited by caspase-11, an enzyme that binds oxP APC and bacterial lipopolysaccharide (LPS).
Abstract: Dendritic cells (DCs) use pattern recognition receptors to detect microorganisms and activate protective immunity. These cells and receptors are thought to operate in an all-or-nothing manner, existing in an immunologically active or inactive state. Here, we report that encounters with microbial products and self-encoded oxidized phospholipids (oxPAPC) induce an enhanced DC activation state, which we call "hyperactive." Hyperactive DCs induce potent adaptive immune responses and are elicited by caspase-11, an enzyme that binds oxPAPC and bacterial lipopolysaccharide (LPS). oxPAPC and LPS bind caspase-11 via distinct domains and elicit different inflammasome-dependent activities. Both lipids induce caspase-11-dependent interleukin-1 release, but only LPS induces pyroptosis. The cells and receptors of the innate immune system can therefore achieve different activation states, which may permit context-dependent responses to infection.
389 citations
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TL;DR: This study shows that a metabolic enzyme can act as a pattern recognition receptor and is caused by release of N-acetylglucosamine that is detected in the cytosol by the glycolytic enzyme hexokinase.
381 citations
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TL;DR: The A2AR–mini-Gs structure highlights both the diversity and similarity in G-protein coupling to GPCRs and hints at the potential complexity of the molecular basis for G- protein specificity.
Abstract: An engineered G protein is used to bind to and stabilize the active conformation of the adenosine A2A receptor, enabling the acquisition of an X-ray crystal structure of this GPCR in an active state. G-protein-coupled receptors (GPCRs) are essential components of signalling networks throughout the body, and about a third of all clinical drugs target GPCRs. The X-ray structures of GPCRs in an active conformation have proved elusive. This paper describes the crystal structure of adenosine A2A receptor bound to a G protein, which represents the first X-ray structure of the fully active state of the receptor. The trick used here involved engineering a G protein — termed mini-Gs — that binds to and stabilizes the active state of the adenosine A2A receptor. The hope is that this mini-Gs will facilitate the crystallization and characterization of other Gs-coupled GPCRs in their active states. G-protein-coupled receptors (GPCRs) are essential components of the signalling network throughout the body. To understand the molecular mechanism of G-protein-mediated signalling, solved structures of receptors in inactive conformations and in the active conformation coupled to a G protein are necessary1,2. Here we present the structure of the adenosine A2A receptor (A2AR) bound to an engineered G protein, mini-Gs, at 3.4 A resolution. Mini-Gs binds to A2AR through an extensive interface (1,048 A2) that is similar, but not identical, to the interface between Gs and the β2-adrenergic receptor3. The transition of the receptor from an agonist-bound active-intermediate state4,5 to an active G-protein-bound state is characterized by a 14 A shift of the cytoplasmic end of transmembrane helix 6 (H6) away from the receptor core, slight changes in the positions of the cytoplasmic ends of H5 and H7 and rotamer changes of the amino acid side chains Arg3.50, Tyr5.58 and Tyr7.53. There are no substantial differences in the extracellular half of the receptor around the ligand binding pocket. The A2AR–mini-Gs structure highlights both the diversity and similarity in G-protein coupling to GPCRs6 and hints at the potential complexity of the molecular basis for G-protein specificity.
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TL;DR: Nongenomic actions expand the repertoire of cellular events controlled by thyroid hormone and can modulate TR-dependent nuclear events.
Abstract: The nongenomic actions of thyroid hormone begin at receptors in the plasma membrane, mitochondria or cytoplasm. These receptors can share structural homologies with nuclear thyroid hormone receptors (TRs) that mediate transcriptional actions of T3, or have no homologies with TR, such as the plasma membrane receptor on integrin αvβ3. Nongenomic actions initiated at the plasma membrane by T4 via integrin αvβ3 can induce gene expression that affects angiogenesis and cell proliferation, therefore, both nongenomic and genomic effects can overlap in the nucleus. In the cytoplasm, a truncated TRα isoform mediates T4-dependent regulation of intracellular microfilament organization, contributing to cell and tissue structure. p30 TRα1 is another shortened TR isoform found at the plasma membrane that binds T3 and mediates nongenomic hormonal effects in bone cells. T3 and 3,5-diiodo-L-thyronine are important to the complex nongenomic regulation of cellular respiration in mitochondria. Thus, nongenomic actions expand the repertoire of cellular events controlled by thyroid hormone and can modulate TR-dependent nuclear events. Here, we review the experimental approaches required to define nongenomic actions of the hormone, enumerate the known nongenomic effects of the hormone and their molecular basis, and discuss the possible physiological or pathophysiological consequences of these actions.
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TL;DR: The human σ1 receptor is an enigmatic endoplasmic-reticulum-resident transmembrane protein implicated in a variety of disorders including depression, drug addiction, and neuropathic pain this paper.
Abstract: The human σ1 receptor is an enigmatic endoplasmic-reticulum-resident transmembrane protein implicated in a variety of disorders including depression, drug addiction, and neuropathic pain. Recently, an additional connection to amyotrophic lateral sclerosis has emerged from studies of human genetics and mouse models. Unlike many transmembrane receptors that belong to large, extensively studied families such as G-protein-coupled receptors or ligand-gated ion channels, the σ1 receptor is an evolutionary isolate with no discernible similarity to any other human protein. Despite its increasingly clear importance in human physiology and disease, the molecular architecture of the σ1 receptor and its regulation by drug-like compounds remain poorly defined. Here we report crystal structures of the human σ1 receptor in complex with two chemically divergent ligands, PD144418 and 4-IBP. The structures reveal a trimeric architecture with a single transmembrane domain in each protomer. The carboxy-terminal domain of the receptor shows an extensive flat, hydrophobic membrane-proximal surface, suggesting an intimate association with the cytosolic surface of the endoplasmic reticulum membrane in cells. This domain includes a cupin-like β-barrel with the ligand-binding site buried at its centre. This large, hydrophobic ligand-binding cavity shows remarkable plasticity in ligand recognition, binding the two ligands in similar positions despite dissimilar chemical structures. Taken together, these results reveal the overall architecture, oligomerization state, and molecular basis for ligand recognition by this important but poorly understood protein.
01 Jan 2016
TL;DR: The current data suggest that the liver of dogs contains functional LDL receptors that are susceptible to metabolic regulation and that a drug-induced increase in the activity of these receptors can contribute to a lowering of plasma levels of LDL-cholesterol.
Abstract: Liver membranes from young beagle dogs were found to possess binding sites that resemble the low density lipo- protein (LDL) receptors originally described in cultured human fibroblasts. Treatment of the dogs with colestipol (a bile acid se- questrant) and mevinolin (a cholesterol synthesis inhibitor) pro- duced a 3-fold increase in LDL binding activity. This increase cor- related with a 2-fold increase in the fractional catabolic rate for intravenously administered human or canine "LI-labeled LDL, suggesting that the increased hepatic receptors were responsible for the enhanced clearance of LDL from plasma. The hepatic lipo- protein receptors of control and drug-treated dogs resembled hu- man fibroblast LDL receptors in that they bound apoprotein E- containing lipoproteins, such as very low density lipoproteins and a subfraction of high density lipoproteins (HDL ), with 10-fold higher affinity than the apoprotein B-containing lipoprotein LDL; failed to bind canine HDL and human HDL3 which are devoid of apoproteins B and E; failed to bind methylated LDL; required cal- cium; and were destroyed by Pronase. Treatment of dogs with mevinolin not only increased the fractional catabolic rate for LDL but also reduced the synthetic rate for the lipoprotein. The current data suggest that the liver of dogs contains functional LDL recep- tors that are susceptible to metabolic regulation and that a drug- induced increase in the activity of these receptors can contribute to a lowering of plasma levels of LDL-cholesterol.
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TL;DR: The CB2 receptor was shown to modulate immune cell functions, both in cellulo and in animal models of inflammatory diseases, suggesting that therapeutic strategies aiming at modulating CB2 signaling could be promising for the treatment of various inflammatory conditions.
Abstract: The CB2 receptor is the peripheral receptor for cannabinoids. It is mainly expressed in immune tissues, highlighting the possibility that the endocannabinoid system has an immunomodulatory role. In this respect, the CB2 receptor was shown to modulate immune cell functions, both in cellulo and in animal models of inflammatory diseases. In this regard, numerous studies have reported that mice lacking the CB2 receptor have an exacerbated inflammatory phenotype. This suggests that therapeutic strategies aiming at modulating CB2 signaling could be promising for the treatment of various inflammatory conditions. Herein, we review the pharmacology of the CB2 receptor, its expression pattern, and the signaling pathways induced by its activation. We next examine the regulation of immune cell functions by the CB2 receptor and the evidence obtained from primary human cells, immortalized cell lines, and animal models of inflammation. Finally, we discuss the possible therapies targeting the CB2 receptor and the questions that remain to be addressed to determine whether this receptor could be a potential target to treat inflammatory disease.
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TL;DR: A modified, recombinant dimerized version of sgp130 (sgp130Fc) has successfully been used to block inflammatory processes in mice and may also be used in the clarification of IL-6 trans-signaling in neurological diseases.
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TL;DR: This X-ray crystallographic structure of the human α4β2 nicotinic receptor provides insights into the architectural principles governing ligand recognition, heteromer assembly, ion permeation and desensitization in this prototypical receptor class.
Abstract: Nicotinic acetylcholine receptors are ligand-gated ion channels that mediate fast chemical neurotransmission at the neuromuscular junction and have diverse signalling roles in the central nervous system. The nicotinic receptor has been a model system for cell-surface receptors, and specifically for ligand-gated ion channels, for well over a century. In addition to the receptors' prominent roles in the development of the fields of pharmacology and neurobiology, nicotinic receptors are important therapeutic targets for neuromuscular disease, addiction, epilepsy and for neuromuscular blocking agents used during surgery. The overall architecture of the receptor was described in landmark studies of the nicotinic receptor isolated from the electric organ of Torpedo marmorata. Structures of a soluble ligand-binding domain have provided atomic-scale insights into receptor-ligand interactions, while high-resolution structures of other members of the pentameric receptor superfamily provide touchstones for an emerging allosteric gating mechanism. All available high-resolution structures are of homopentameric receptors. However, the vast majority of pentameric receptors (called Cys-loop receptors in eukaryotes) present physiologically are heteromeric. Here we present the X-ray crystallographic structure of the human α4β2 nicotinic receptor, the most abundant nicotinic subtype in the brain. This structure provides insights into the architectural principles governing ligand recognition, heteromer assembly, ion permeation and desensitization in this prototypical receptor class.
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TL;DR: The current review provides an update on melatonin receptors by the corresponding subcommittee of the International Union of Basic and Clinical Pharmacology, and highlights recent developments of melatonin receptor ligands, including radioligands, and gives anupdate on the latest phenotyping results ofmelatonin receptor knockout mice.
Abstract: Melatonin receptors are seven transmembrane-spanning proteins belonging to the G protein-coupled receptor super-family. In mammals, two melatonin receptor subtypes exit MT1 and MT2 encoded by the MTNR1A and MTNR1B genes, respectively. The current review provides an update on melatonin receptors by the corresponding sub-committee of the International Union of Basic and Clinical Pharmacology. We will highlight recent developments of melatonin receptor ligands, including radioligands and give an update on the latest phenotyping results of melatonin receptor knockout mice. The current status and perspectives of the structure of melatonin receptor structures will be summarized. The physiological importance of melatonin receptor dimers and biologically important and type 2 diabetes-associated genetic variants of melatonin receptors will be discussed. The role of melatonin receptors in physiology and disease will be further exemplified by its functions in the immune system and the central nervous system. Finally, antioxidant and free radical scavenger properties of melatonin and its relation to melatonin receptors will be critically addressed.
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TL;DR: It is shown that acute cannabinoid-induced memory impairment in mice requires activation of hippocampal mtCB1 receptors, and this data reveal that bioenergetic processes are primary acute regulators of cognitive functions.
Abstract: Cellular activity in the brain depends on the high energetic support provided by mitochondria, the cell organelles which use energy sources to generate ATP. Acute cannabinoid intoxication induces amnesia in humans and animals, and the activation of type-1 cannabinoid receptors present at brain mitochondria membranes (mtCB1) can directly alter mitochondrial energetic activity. Although the pathological impact of chronic mitochondrial dysfunctions in the brain is well established, the involvement of acute modulation of mitochondrial activity in high brain functions, including learning and memory, is unknown. Here, we show that acute cannabinoid-induced memory impairment in mice requires activation of hippocampal mtCB1 receptors. Genetic exclusion of CB1 receptors from hippocampal mitochondria prevents cannabinoid-induced reduction of mitochondrial mobility, synaptic transmission and memory formation. mtCB1 receptors signal through intra-mitochondrial Gαi protein activation and consequent inhibition of soluble-adenylyl cyclase (sAC). The resulting inhibition of protein kinase A (PKA)-dependent phosphorylation of specific subunits of the mitochondrial electron transport system eventually leads to decreased cellular respiration. Hippocampal inhibition of sAC activity or manipulation of intra-mitochondrial PKA signalling or phosphorylation of the Complex I subunit NDUFS2 inhibit bioenergetic and amnesic effects of cannabinoids. Thus, the G protein-coupled mtCB1 receptors regulate memory processes via modulation of mitochondrial energy metabolism. By directly linking mitochondrial activity to memory formation, these data reveal that bioenergetic processes are primary acute regulators of cognitive functions.
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TL;DR: Current knowledge on proximal tubule endocytic receptor function and regulation, and their role in renal development, protein reabsorption, albumin uptake, and normal renal physiology are reviewed.
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TL;DR: It is demonstrated that Fc receptor binding augmented the production of proinflammatory cytokines in a two-way mixed leukocyte reaction using a fully human anti-CD73, and this co-blockade limits tumor initiation, growth, and metastasis.
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TL;DR: Direct observation of the conformational equilibria of ligand-dependent G-protein-coupled receptor and deduction of the underlying mechanisms of receptor activation will have wide-reaching implications for the understanding of the function of G- proteins in health and disease.
Abstract: Conformational selection and induced fit are two prevailing mechanisms to explain the molecular basis for ligand-based activation of receptors. G-protein-coupled receptors are the largest class of cell surface receptors and are important drug targets. A molecular understanding of their activation mechanism is critical for drug discovery and design. However, direct evidence that addresses how agonist binding leads to the formation of an active receptor state is scarce. Here we use (19)F nuclear magnetic resonance to quantify the conformational landscape occupied by the adenosine A2A receptor (A2AR), a prototypical class A G-protein-coupled receptor. We find an ensemble of four states in equilibrium: (1) two inactive states in millisecond exchange, consistent with a formed (state S1) and a broken (state S2) salt bridge (known as 'ionic lock') between transmembrane helices 3 and 6; and (2) two active states, S3 and S3', as identified by binding of a G-protein-derived peptide. In contrast to a recent study of the β2-adrenergic receptor, the present approach allowed identification of a second active state for A2AR. Addition of inverse agonist (ZM241385) increases the population of the inactive states, while full agonists (UK432097 or NECA) stabilize the active state, S3', in a manner consistent with conformational selection. In contrast, partial agonist (LUF5834) and an allosteric modulator (HMA) exclusively increase the population of the S3 state. Thus, partial agonism is achieved here by conformational selection of a distinct active state which we predict will have compromised coupling to the G protein. Direct observation of the conformational equilibria of ligand-dependent G-protein-coupled receptor and deduction of the underlying mechanisms of receptor activation will have wide-reaching implications for our understanding of the function of G-protein-coupled receptor in health and disease.
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TL;DR: This review focuses on the research progress about the role of TLR4 activation in infectious and noninfectious inflammation and the effects ofTLR4 signaling in some pathological conditions.
Abstract: Toll-like receptor 4 (TLR4) belongs to the family of pattern recognition receptors (PRRs). They are highly conserved receptors that recognize conserved pathogen-associated molecular patterns (PAMPs), thus representing the first line of defense against infections. TLR4 has been long recognized as the sensing receptor for gram-negative lipopolysaccharide (LPS). In addition, it also binds endogenous molecules produced as a result of tissue injury. Hence, TLR4 represents a key receptor on which both infectious and noninfectious stimuli converge to induce a proinflammatory response. TLR4-mediated inflammation, triggered by exogenous or endogenous ligands, is also involved in several acute and chronic diseases, having a pivotal role as amplifier of the inflammatory response. This review focuses on the research progress about the role of TLR4 activation in infectious and noninfectious (e.g., sterile) inflammation and the effects of TLR4 signaling in some pathological conditions.
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TL;DR: Development of antibody–sialidase conjugates that enhance tumor cell susceptibility to antibody-dependent cell-mediated cytotoxicity (ADCC) by selective desialylation of the tumor cell glycocalyx is reported.
Abstract: Cell surface sialosides constitute a central axis of immune modulation that is exploited by tumors to evade both innate and adaptive immune destruction. Therapeutic strategies that target tumor-associated sialosides may therefore potentiate antitumor immunity. Here, we report the development of antibody–sialidase conjugates that enhance tumor cell susceptibility to antibody-dependent cell-mediated cytotoxicity (ADCC) by selective desialylation of the tumor cell glycocalyx. We chemically fused a recombinant sialidase to the human epidermal growth factor receptor 2 (HER2)-specific antibody trastuzumab through a C-terminal aldehyde tag. The antibody–sialidase conjugate desialylated tumor cells in a HER2-dependent manner, reduced binding by natural killer (NK) cell inhibitory sialic acid-binding Ig-like lectin (Siglec) receptors, and enhanced binding to the NK-activating receptor natural killer group 2D (NKG2D). Sialidase conjugation to trastuzumab enhanced ADCC against tumor cells expressing moderate levels of HER2, suggesting a therapeutic strategy for cancer patients with lower HER2 levels or inherent trastuzumab resistance. Precision glycocalyx editing with antibody–enzyme conjugates is therefore a promising avenue for cancer immune therapy.
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TL;DR: This study provides a novel signaling paradigm, whereby a mutated chaperone constitutively activates cytokine receptor signaling, and knocking down either MPL/TpoR or JAK2 in megakaryocytic progenitors from patients carrying CALR mutations inhibited cytokine-independent megakARYocytic colony formation.
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TL;DR: Stabilization of two distinct β2AR conformations using single domain camelid antibodies (nanobodies) are reported—a previously described positive allosteric nanobody (Nb80) and a newly identified negative allosterics nanobodies (nb60) and demonstrate that ligands can initiate a wide range of cellular responses by differentially stabilizing multiple receptor states.
Abstract: G-protein-coupled receptors (GPCRs) modulate many physiological processes by transducing a variety of extracellular cues into intracellular responses. Ligand binding to an extracellular orthosteric pocket propagates conformational change to the receptor cytosolic region to promote binding and activation of downstream signalling effectors such as G proteins and β-arrestins. It is well known that different agonists can share the same binding pocket but evoke unique receptor conformations leading to a wide range of downstream responses (‘efficacy’). Furthermore, increasing biophysical evidence, primarily using the β2-adrenergic receptor (β2AR) as a model system, supports the existence of multiple active and inactive conformational states. However, how agonists with varying efficacy modulate these receptor states to initiate cellular responses is not well understood. Here we report stabilization of two distinct β2AR conformations using single domain camelid antibodies (nanobodies)—a previously described positive allosteric nanobody (Nb80) and a newly identified negative allosteric nanobody (Nb60). We show that Nb60 stabilizes a previously unappreciated low-affinity receptor state which corresponds to one of two inactive receptor conformations as delineated by X-ray crystallography and NMR spectroscopy. We find that the agonist isoprenaline has a 15,000-fold higher affinity for β2AR in the presence of Nb80 compared to the affinity of isoprenaline for β2AR in the presence of Nb60, highlighting the full allosteric range of a GPCR. Assessing the binding of 17 ligands of varying efficacy to the β2AR in the absence and presence of Nb60 or Nb80 reveals large ligand-specific effects that can only be explained using an allosteric model which assumes equilibrium amongst at least three receptor states. Agonists generally exert efficacy by stabilizing the active Nb80-stabilized receptor state (R80). In contrast, for a number of partial agonists, both stabilization of R80 and destabilization of the inactive, Nb60-bound state (R60) contribute to their ability to modulate receptor activation. These data demonstrate that ligands can initiate a wide range of cellular responses by differentially stabilizing multiple receptor states.
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TL;DR: Comparison of crystal structures of the M1 and M4 muscarinic receptors bound to the inverse agonist, tiotropium, reveals differences in the orthosteric and allosteric binding sites that contribute to a role in drug selectivity at this important receptor family.
Abstract: Muscarinic M1–M5 acetylcholine receptors are G-protein-coupled receptors that regulate many vital functions of the central and peripheral nervous systems. In particular, the M1 and M4 receptor subtypes have emerged as attractive drug targets for treatments of neurological disorders, such as Alzheimer’s disease and schizophrenia, but the high conservation of the acetylcholine-binding pocket has spurred current research into targeting allosteric sites on these receptors. Here we report the crystal structures of the M1 and M4 muscarinic receptors bound to the inverse agonist, tiotropium. Comparison of these structures with each other, as well as with the previously reported M2 and M3 receptor structures, reveals differences in the orthosteric and allosteric binding sites that contribute to a role in drug selectivity at this important receptor family. We also report identification of a cluster of residues that form a network linking the orthosteric and allosteric sites of the M4 receptor, which provides new insight into how allosteric modulation may be transmitted between the two spatially distinct domains. X-ray crystal structures of the M1 and M4 muscarinic acetylcholine receptors, revealing differences in the orthosteric and allosteric binding sites that help to explain the subtype selectivity of drugs targeting this family of receptors. Arthur Christopoulos and colleagues present the first X-ray crystal structures of the M1 and M4 muscarinic acetylcholine receptors, G-protein-coupled receptors (GPCRs) that regulate many vital functions of the central and peripheral nervous systems. The structures reveal differences in the orthosteric and allosteric binding sites that help to explain the subtype selectivity of drugs targeting this family of receptors. The M1 and M4 receptor subtypes are potential drug targets for treatments of neurological disorders, such as Alzheimer's disease and schizophrenia.
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TL;DR: It is demonstrated that the coreceptor CD28 is strongly preferred over the TCR as a target for dephosphorylation by PD-1- recruited Shp2 phosphatase, suggesting that costimulatory pathways may play unexpected roles in regulating effector T cell function and therapeutic responses to anti-PD-L1/PD-1.
Abstract: Programmed death-1 (PD-1) is a co-inhibitory receptor that suppresses T cell activation and is an
important cancer immunotherapy target. Upon activation by its ligand PD-L1, PD-1 is thought to
suppress signaling through the T cell receptor (TCR). Here, by titrating the strength of PD-1
signaling in both biochemical reconstitution systems and in T cells, we demonstrate that the
coreceptor CD28 is strongly preferred over the TCR as a target for dephosphorylation by PD-1-
recruited Shp2 phosphatase. We also show that PD-1 colocalizes with the costimulatory receptor
CD28 in plasma membrane microclusters but partially segregates from the TCR. These results
reveal that PD-1 suppresses T cell function primarily by inactivating CD28 signaling, suggesting
that costimulatory pathways may play unexpected roles in regulating effector T cell function and
therapeutic responses to anti-PD-L1/PD-1.
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TL;DR: It is suggested that blocking S100A8/A9 activity exerts beneficial effects on disease activity in animal models of autoimmune diseases including multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis and inflammatory bowel disease.
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TL;DR: Cenicriviroc displayed potent anti-inflammatory and antifibrotic activity in a range of animal fibrosis models, supporting human testing for fibrotic diseases.
Abstract: Background & Aims
Interactions between C-C chemokine receptor types 2 (CCR2) and 5 (CCR5) and their ligands, including CCL2 and CCL5, mediate fibrogenesis by promoting monocyte/macrophage recruitment and tissue infiltration, as well as hepatic stellate cell activation. Cenicriviroc (CVC) is an oral, dual CCR2/CCR5 antagonist with nanomolar potency against both receptors. CVC’s anti-inflammatory and antifibrotic effects were evaluated in a range of preclinical models of inflammation and fibrosis.