Class A G-protein-coupled receptors (GPCRs) influence virtually every aspect of human physiology. Understanding receptor activation mechanism is critical for discovering novel therapeutics since ...about one-third of all marketed drugs target members of this family. GPCR activation is an allosteric process that couples agonist binding to G-protein recruitment, with the hallmark outward movement of transmembrane helix 6 (TM6). However, what leads to TM6 movement and the key residue level changes of this movement remain less well understood. Here, we report a framework to quantify conformational changes. By analyzing the conformational changes in 234 structures from 45 class A GPCRs, we discovered a common GPCR activation pathway comprising of 34 residue pairs and 35 residues. The pathway unifies previous findings into a common activation mechanism and strings together the scattered key motifs such as CWxP, DRY, Na
pocket, NPxxY and PIF, thereby directly linking the bottom of ligand-binding pocket with G-protein coupling region. Site-directed mutagenesis experiments support this proposition and reveal that rational mutations of residues in this pathway can be used to obtain receptors that are constitutively active or inactive. The common activation pathway provides the mechanistic interpretation of constitutively activating, inactivating and disease mutations. As a module responsible for activation, the common pathway allows for decoupling of the evolution of the ligand binding site and G-protein-binding region. Such an architecture might have facilitated GPCRs to emerge as a highly successful family of proteins for signal transduction in nature.
The tumor microenvironment confers profound resistance to anti-cancer immunotherapy. By targeting LIGHT, a member of the TNF superfamily of cytokines, to tumor vessels via a vascular targeting ...peptide (VTP), we developed a reagent with the dual ability to modulate the angiogenic vasculature and to induce tertiary lymphoid structures (TLSs). LIGHT-VTP triggered the influx of endogenous T cells into autochthonous or syngeneic tumors, which are resistant to immunotherapy. LIGHT-VTP in combination with checkpoint inhibition generated a large number of intratumoral effector and memory T cells with ensuing survival benefits, while the addition of anti-tumor vaccination achieved maximal therapeutic efficacy. Thus, the combination treatments stimulated the trafficking of pre-existing endogenous effector T cells as well as their intratumoral activation and were more successful than current immunotherapies, which fail due to tumor-intrinsic resistance mechanisms.
We report acute antibody responses to SARS-CoV-2 in 285 patients with COVID-19. Within 19 days after symptom onset, 100% of patients tested positive for antiviral immunoglobulin-G (IgG). ...Seroconversion for IgG and IgM occurred simultaneously or sequentially. Both IgG and IgM titers plateaued within 6 days after seroconversion. Serological testing may be helpful for the diagnosis of suspected patients with negative RT-PCR results and for the identification of asymptomatic infections.
Abstract
Background
The high cost and insufficient supply of human papillomavirus (HPV) vaccines have slowed the pace of controlling cervical cancer. A phase III clinical trial was conducted to ...evaluate the efficacy, safety, and immunogenicity of a novel Escherichia coli-produced bivalent HPV-16/18 vaccine.
Methods
A multicenter, randomized, double-blind trial started on November 22, 2012 in China. In total, 7372 eligible women aged 18–45 years were age-stratified and randomly assigned to receive three doses of the test or control (hepatitis E) vaccine at months 0, 1, and 6. Co-primary endpoints included high-grade genital lesions and persistent infection (over 6 months) associated with HPV-16/18. The primary analysis was performed on a per-protocol susceptible population of individuals who were negative for relevant HPV type-specific neutralizing antibodies (at day 0) and DNA (at day 0 through month 7) and who received three doses of the vaccine. This report presents data from a prespecified interim analysis used for regulatory submission.
Results
In the per-protocol cohort, the efficacies against high-grade genital lesions and persistent infection were 100.0% (95% confidence interval = 55.6% to 100.0%, 0 of 3306 in the vaccine group vs 10 of 3296 in the control group) and 97.8% (95% confidence interval = 87.1% to 99.9%, 1 of 3240 vs 45 of 3246), respectively. The side effects were mild. No vaccine-related serious adverse events were noted. Robust antibody responses for both types were induced and persisted for at least 42 months.
Conclusions
The E coli-produced HPV-16/18 vaccine is well tolerated and highly efficacious against HPV-16/18–associated high-grade genital lesions and persistent infection in women.
Abstract
Background
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel β-coronavirus, causes severe pneumonia and has spread throughout the globe rapidly. The disease associated ...with SARS-CoV-2 infection is named coronavirus disease 2019 (COVID-19). To date, real-time reverse-transcription polymerase chain reaction (RT-PCR) is the only test able to confirm this infection. However, the accuracy of RT-PCR depends on several factors; variations in these factors might significantly lower the sensitivity of detection.
Methods
In this study, we developed a peptide-based luminescent immunoassay that detected immunoglobulin (Ig)G and IgM. The assay cutoff value was determined by evaluating the sera from healthy and infected patients for pathogens other than SARS-CoV-2.
Results
To evaluate assay performance, we detected IgG and IgM in the sera from confirmed patients. The positive rate of IgG and IgM was 71.4% and 57.2%, respectively.
Conclusions
Therefore, combining our immunoassay with real-time RT-PCR might enhance the diagnostic accuracy of COVID-19.
A peptide-based magnetic chemiluminescence enzyme immunoassay for the detection of SARS-CoV-2 antibodies was developed; 71.4% (197 of 276) and 57.2% (158 of 276) of the COVID-19 inpatients were positive for IgG and IgM against SARS-CoV-2.
Background and Purpose
The anthelmintic drug nitazoxanide has a mitochondrial uncoupling effect. Mitochondrial uncouplers have been proven to inhibit smooth muscle cell proliferation and migration, ...inhibit NLRP3 inflammasome activation of macrophages and improve dyslipidaemia. Therefore, we aimed to demonstrate that nitazoxanide would protect against atherosclerosis.
Experimental Approach
The mitochondrial oxygen consumption of cells was measured by using the high‐resolution respirometry system, Oxygraph‐2K. The proliferation and migration of A10 cells were measured by using Edu immunofluorescence staining, wound‐induced migration and the Boyden chamber assay. Protein levels were measured by using the western blot technique. ApoE (−/−) mice were fed with a Western diet to establish an atherosclerotic model in vivo.
Key Results
The in vitro experiments showed that nitazoxanide and tizoxanide had a mitochondrial uncoupling effect and activated cellular AMPK. Nitazoxanide and tizoxanide inhibited serum‐ and PDGF‐induced proliferation and migration of A10 cells. Nitazoxanide and tizoxanide inhibited NLRP3 inflammasome activation in RAW264.7 macrophages, the mechanism by which involved the AMPK/IκBα/NF‐κB pathway. Nitazoxanide and tizoxanide also induced autophagy in A10 cells and RAW264.7 macrophages. The in vivo experiments demonstrated that oral administration of nitazoxanide reduced the increase in serum IL‐1β and IL‐6 levels and suppressed atherosclerosis in Western diet‐fed ApoE (−/−) mice.
Conclusion and Implications
Nitazoxanide inhibits the formation of atherosclerotic plaques in ApoE (−/−) mice fed on a Western diet. In view of nitazoxanide being an antiprotozoal drug already approved by the FDA, we propose it as a novel anti‐atherosclerotic drug with clinical translational potential.
A series of rhodium complexes bearing sterically and electronically tunable cyclopentadienyl ligands, prepared by utilizing Co2(CO)8-mediated 2+2+1 cyclization as a key step, were synthesized. In the ...presence of 2.5 mol% of Cp m Rh4, unprecedented enantioselective 4+1 annulation reaction of benzamides and alkenes was achieved with a broad substrate scope under mild reaction conditions, providing a variety of isoindolinones with excellent regio- and enantioselectivity (up to 94% yield, 97:3 er). Preliminary mechanistic studies suggest that the reaction involves an oxidative Heck reaction and an intramolecular enantioselective alkene hydroamination reaction.
Background and Purpose
Piezo1 channels are mechanosensitive cationic channels that are activated by mechanical stretch or shear stress. Endothelial Piezo1 activation by shear stress caused by blood ...flow induces ATP release from endothelial cells; however, the link between shear stress and endothelial ATP production is unclear.
Experimental Approach
The mitochondrial respiratory function of cells was measured by using high‐resolution respirometry system Oxygraph‐2k. The intracellular Ca2+ concentration was evaluated by using Fluo‐4/AM and mitochondrial Ca2+ concentration by Rhod‐2/AM.
Key Results
The specific Piezo1 channel activator Yoda1 or its analogue Dooku1 increased Ca2+i in human umbilical vein endothelial cells (HUVECs), and both Yoda1 and Dooku1 increased mitochondrial oxygen consumption rates (OCRs) and mitochondrial ATP production in HUVECs and primary cultured rat aortic endothelial cells (RAECs). Knockdown of Piezo1 inhibited Yoda1‐ and Dooku1‐induced increases of mitochondrial OCRs and mitochondrial ATP production in HUVECs. The shear stress mimetics, Yoda1 and Dooku1, and the Piezo1 knock‐down technique also demonstrated that Piezo1 activation increased glycolysis in HUVECs. Chelating extracellular Ca2+ with EGTA or chelating cytosolic Ca2+ with BAPTA‐AM did not affect Yoda1‐ and Dooku1‐induced increases of mitochondrial OCRs and ATP production, but chelating cytosolic Ca2+ inhibited Yoda1‐ and Dooku1‐induced increase of glycolysis. Confocal microscopy showed that Piezo1 channels are present in mitochondria of endothelial cells, and Yoda1 and Dooku1 increased mitochondrial Ca2+ in endothelial cells.
Conclusion and Implications
Piezo1 channel activation stimulates ATP production through enhancing mitochondrial respiration and glycolysis in vascular endothelial cells, suggesting a novel role of Piezo1 channel in endothelial ATP production.
Nitazoxanide is a therapeutic anthelmintic drug. Our previous studies found that nitazoxanide and its metabolite tizoxanide activated adenosine 5'-monophosphate-activated protein kinase (AMPK) and ...inhibited signal transducer and activator of transcription 3 (STAT3) signals. As AMPK activation and/or STAT3 inhibition are targets for treating pulmonary fibrosis, we hypothesized that nitazoxanide would be effective in experimental pulmonary fibrosis.
The mitochondrial oxygen consumption rate of cells was measured by using the high-resolution respirometry system Oxygraph-2K. The mitochondrial membrane potential of cells was evaluated by tetramethyl rhodamine methyl ester (TMRM) staining. The target protein levels were measured by using western blotting. The mice pulmonary fibrosis model was established through intratracheal instillation of bleomycin. The examination of the lung tissues changes were carried out using haematoxylin and eosin (H&E), and Masson staining.
Nitazoxanide and tizoxanide activated AMPK and inhibited STAT3 signalling in human lung fibroblast cells (MRC-5 cells). Nitazoxanide and tizoxanide inhibited transforming growth factor-β1 (TGF-β1)-induced proliferation and migration of MRC-5 cells, collagen-I and α-smooth muscle cell actin (α-SMA) expression, and collagen-I secretion from MRC-5 cells. Nitazoxanide and tizoxanide inhibited epithelial-mesenchymal transition (EMT) and inhibited TGF-β1-induced Smad2/3 activation in mouse lung epithelial cells (MLE-12 cells). Oral administration of nitazoxanide reduced the bleomycin-induced mice pulmonary fibrosis and, in the established bleomycin-induced mice, pulmonary fibrosis. Delayed nitazoxanide treatment attenuated the fibrosis progression.
Nitazoxanide improves the bleomycin-induced pulmonary fibrosis in mice, suggesting a potential application of nitazoxanide for pulmonary fibrosis treatment in the clinic.
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