In humans, Vγ9Vδ2 T cells detect tumor cells and microbial infections, including Mycobacterium tuberculosis, through recognition of small pyrophosphate containing organic molecules known as ...phosphoantigens (pAgs). Key to pAg-mediated activation of Vγ9Vδ2 T cells is the butyrophilin 3A1 (BTN3A1) protein that contains an intracellular B30.2 domain critical to pAg reactivity. Here, we have demonstrated through structural, biophysical, and functional approaches that the intracellular B30.2 domain of BTN3A1 directly binds pAg through a positively charged surface pocket. Charge reversal of pocket residues abrogates binding and Vγ9Vδ2 T cell activation. We have also identified a gain-of-function mutation within this pocket that, when introduced into the B30.2 domain of the nonstimulatory BTN3A3 isoform, transfers pAg binding ability and Vγ9Vδ2 T cell activation. These studies demonstrate that internal sensing of changes in pAg metabolite concentrations by BTN3A1 molecules is a critical step in Vγ9Vδ2 T cell detection of infection and tumorigenesis.
•Structure of BTN3A1 intracellular B30.2 domain reveals positively charged pocket•B30.2 domain directly binds phosphoantigens through positively charged pocket•Phosphoantigen binding by the B30.2 domain is necessary to stimulate Vγ9Vδ2 T cells
•Effect of strains CL-1 and X30 on Cd immobilization and uptake of rape was evaluated.•CL-1 and X30 increased pH and immobilized Cd in the solution and rhizosphere soil.•CL-1 and X30 increased ...polyamine concentration in the solution and rhizosphere soil.•CL-1 was better to increase arginine decarboxylase-producing bacteria in the soil.•CL-1 was better to decrease the rhizosphere soil available Cd and rapeseed Cd uptake.
Two Cd-immobilizing and polyamine-producing bacteria Serratia liquefaciens CL-1 and Bacillus thuringiensis X30 were characterized for their effects on Cd immobilization, pH, and polyamine production in the solution and the rapeseed biomass and Cd uptake of Brassica napus Qinyou-10 in Cd-contaminated soil. These strains significantly increased pH and reduced water-soluble Cd concentration (25–76%) compared to the controls. Furthermore, strain CL-1 produced more polyamine (71–192%) in the solution than strain X30. Cell surface absorbed Cd content was increased by 23-56% in the presence of strain CL-1 compared to strain X30. The strains significantly increased the rapeseed biomass (12–32%), pH, polyamine content (70–244%), and relative abundance (21-49%) of arginine decarboxylase-producing bacteria (ADPB) of the rhizosphere soils but decreased DTPA-extractable Cd content and rapeseed Cd uptake compared to the controls. Notably, strain CL-1 had higher ability to reduce the rapeseed Cd and DTPA-extractable Cd contents and increase the abundance of ADPB than strain X30. Our results showed the distinct impact of these strains on the rapeseed Cd uptake and available Cd content and suggested that these strains reduced the available Cd and rapeseed Cd uptake by increasing the cell adsorption of Cd, abundance of ADPB, polyamine production, and pH in the rhizosphere soils.
To disclose how phosphorus deficiency influence phytoremediation of Cd contamination using poplars, root architecture, Cd absorption, Cd translocation and antioxidant defense in poplar roots were ...investigated using a clone of Populus × euramericana. Root growth was unaltered by Cd exposure regardless of P conditions, while the degree of root proliferation upon P deficiency was changed by high level of Cd exposure. The concentration and content of Cd accumulation in roots were increased by P deficiency. This can be partially explained by the increased expression of genes encoding PM H + -ATPase under the combined conditions of P deficiency and high Cd exposure, which enhanced Cd2+-H+ exchanges and led to an increment of Cd uptake under P deficiency. Despite of the increasing Cd accumulation in roots, the translocation of Cd from roots to aerial tissues sharply decreased upon P deficiency. The relative expression of genes responsible for Cd translocation (HMA4) decreased upon P deficiency and thus inhibited Cd translocation via xylem. GR activity was decreased by P deficiency, which can inhibit the form of GSH and GSH–Cd complexes and decrease Cd translocation via GSH–Cd complexes. The transportation of PC–Cd complexes into vacuole decreased under P deficiency as a result of the low expression of PCS and ABCC1, and thus suppressed Cd tolerance and Cd detoxification in roots. Moreover, P deficiency decreased the levels of antioxidase (GR and CAT) and phytohormones including JA, ABA and GA3, which synchronously reduced antioxidant capacity in roots.
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•The adaptive root proliferation upon P deficiency was modified by Cd exposure.•P deficiency stimulated the expression of PM H + -ATPase and increased root Cd uptake.•P deficiency decreased the expression of genes for Cd translocation and detoxification.•P deficiency decreased GR activity and reduced Cd translocation via GSH–Cd complexes.•High Cd concentration in roots inhibited antioxidant enzymes and Cd translocation.
Cadmium (Cd) pollution in agricultural soils has exerted a serious threat due to continuous application of pesticides, fertilizers, and wastewater irrigation. The present study aimed to test the ...efficiency of KOH-modified and non-modified rice straw-derived biochar (KBC and BC, respectively) for reducing Cd solubility and bioavailability in Cd-contaminated soil. Cadmium-contaminated soil was incubated for 60 d with 15 and 30 g kg−1 BC and KBC. At the end of incubation, Cd mobility was estimated by the European Community Bureau of Reference sequential extraction and toxicity characteristic leaching procedure (TCLP), while bioavailability was determined using 1 mol L−1 NH4NO3 extraction. The bioavailability risk index and bioaccessibility, assessed by a simple bioaccessibility extraction test, of Cd were used to examine the potential effects of Cd on living organisms. The results indicated that application of both KBC and BC significantly increased soil pH, cation exchange capacity, nutrients, and organic carbon. The soluble fraction of Cd was significantly decreased by 30.3% and 27.4%, respectively, with the addition of KBC and BC at 30 g kg−1 compared to the control (without biochar addition). Similarly, the bioaccessible Cd was significantly decreased by 32.4% and 25.2%, respectively, with the addition of KBC and BC at 30 g kg−1 compared to the control. In addition, both KBC and BC significantly reduced Cd leaching in the TCLP and NH4NO3-extractable Cd in the amended soil compared to the control. The reduction in Cd solubility and bioaccessibility by KBC and BC may be due to significant increases in soil pH and surface complexation. Overall, KBC at an application rate of 30 g kg−1 demonstrated positive results as soil amendment for Cd immobilization, and reduced bioaccessible Cd in contaminated soil.
Stabilization techniques are vital in controlling Cd soil pollution. Nano zero valent iron (nZVI) has been extensively utilized for Cd remediation owing to its robust adsorption and reactivity. ...However, the environmental stress-induced stability of Cd after nZVI addition remains unclear. A pot experiment was conducted to evaluate the Cd bioavailability in continuously flooded (130 d) soil after stabilization with nZVI. The findings indicated that nZVI application did not result in a decline in Cd concentration in rice, as compared to the no-nZVI control. Additionally, nZVI simultaneously increased the available Cd concentration, iron-manganese oxide-bound (OX) Mn fraction, and relative abundance of Fe(III)-reducing bacteria, but it decreased OX-Cd and Mn availability in soil. Cadmium in rice tissues was positively correlated with the available Cd in soil. The results of subsequent adsorption tests demonstrated that CdO was the product of Cd adsorption by the nZVI aging products. Conversely, Mn2+ decreased the adsorption capacity of Cd-containing solutions. These results underscore the crucial role of both biotic and abiotic factors in undermining the stabilization of nZVI under continuous flooding conditions. This study offers novel insights into the regulation of nZVI-mediated Cd stabilization efficiency in conjunction with biological inhibitors and functional modification techniques.
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•Stabilization effect of nZVI weakened and soil Cd remobilization appeared.•High doses of nZVI even led to an increase in grain Cd concentration.•High soil Mn2+ competed for Cd2+ adsorption sites in secondary iron (hydro)oxides.
CD69 is a membrane‐bound, type II C‐lectin receptor. It is a classical early marker of lymphocyte activation due to its rapid appearance on the surface of the plasma membrane after stimulation. CD69 ...is expressed by several subsets of tissue resident immune cells, including resident memory T (TRM) cells and gamma delta (γδ) T cells, and is therefore considered a marker of tissue retention. Recent evidence has revealed that CD69 regulates some specific functions of selected T‐cell subsets, determining the migration‐retention ratio as well as the acquisition of effector or regulatory phenotypes. Specifically, CD69 regulates the differentiation of regulatory T (Treg) cells as well as the secretion of IFN‐γ, IL‐17, and IL‐22. The identification of putative CD69 ligands, such as Galectin‐1 (Gal‐1), suggests that CD69‐induced signaling can be regulated not only during cognate contacts between T cells and antigen‐presenting cells in lymphoid organs, but also in the periphery, where cytokines and other metabolites control the final outcome of the immune response. Here, we will discuss new aspects of the molecular signaling mediated by CD69 and its involvement in the metabolic reprogramming regulating TH‐effector lineages.
CD69 associates to LAT1 and controls its plasma membrane expression and amino acid transporter activity in T lymphocytes.
Sustainable food production for steadily growing world's population under the conditions of increasing environmental stress and soil pollution is a challenge that calls for optimization of farmland ...resource management. Soybean (Glycine max. L. Merr) as one of the world's most important protein crops can play a leading role in addressing global food security provided it fulfills safety requirements, in particular with respect to Cd level. The aim of this comparative study was elaborating efficient methods for the selection of soybean cultivars assuring safe Cd contents for food/feed purposes. The pot culture experiment was conducted using 15 soybean cultivars grown in soil moderately polluted with Cd (1.98 mg kg−1), and in unpolluted soil (0.15 mg Cd kg−1) as a control. The evaluation was based on the novel Cd concentration/load trend analysis in plant tissues, Seed Accumulation Factors SAFn and Cd load balance. The soybean demonstrated fundamentally different response of the same cultivars to low and moderate Cd concentrations in soil. In cultivars grown in unpolluted soil, besides genetically determined detoxification factors, important seed protective role played Cd accumulation in stem, leaves and root (Seed Accumulation Factor SAFn<0.5, Cd load reduction in bean by 25–82%). In the moderately polluted soil, the most essential effect on Cd accumulation in seed exerted a plant genotype determining Cd flux and translocation from soil to shoot via root (Enrichment Factor EF < 1), while seed protection by accumulating Cd in other plant tissues was weak, declining or none (SAFn >0.5 up to >1, whereas Cd load in bean ranged from −23 to +11% related to mean value in shoot). Root to shoot flux rate was found to be a decisive factor in Cd enrichment in soybean seed at the elevated soil pollution with Cd. The efficient screening for safe Cd content in soybean should be thus based on EF and Cd concentrations in shoot at the actual target soil pollution level.
Vγ9Vδ2 T cells respond in a TCR-dependent fashion to both microbial and host-derived pyrophosphate compounds (phosphoantigens, or P-Ag). Butyrophilin-3A1 (BTN3A1), a protein structurally related to ...the B7 family of costimulatory molecules, is necessary but insufficient for this process. We performed radiation hybrid screens to uncover direct TCR ligands and cofactors that potentiate BTN3A1’s P-Ag sensing function. These experiments identified butyrophilin-2A1 (BTN2A1) as essential to Vγ9Vδ2 T cell recognition. BTN2A1 synergised with BTN3A1 in sensitizing P-Ag-exposed cells for Vγ9Vδ2 TCR-mediated responses. Surface plasmon resonance experiments established Vγ9Vδ2 TCRs used germline-encoded Vγ9 regions to directly bind the BTN2A1 CFG-IgV domain surface. Notably, somatically recombined CDR3 loops implicated in P-Ag recognition were uninvolved. Immunoprecipitations demonstrated close cell-surface BTN2A1-BTN3A1 association independent of P-Ag stimulation. Thus, BTN2A1 is a BTN3A1-linked co-factor critical to Vγ9Vδ2 TCR recognition. Furthermore, these results suggest a composite-ligand model of P-Ag sensing wherein the Vγ9Vδ2 TCR directly interacts with both BTN2A1 and an additional ligand recognized in a CDR3-dependent manner.
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•Radiation hybrids identify BTN2A1 as crucial for Vγ9Vδ2 phosphoantigen (P-Ag) sensing•BTN2A1 binds directly to the T cell receptor via germline-encoded regions of Vγ9•Cell-surface BTN2A1 associates directly with BTN3A1 independent of P-Ag stimulation•The Vγ9-BTN2A1 interaction modality suggests an additional CDR3-dependent TCR ligand
Karunakaran et al. find that butyrophilin 2A1 (BTN2A1) associates with BTN3A1 on the cell surface and binds directly to germline-encoded regions of the Vγ9 chain of the Vγ9Vδ2 TCR. Thus, BTN2A1 collaborates with BTN3A1 to potentiate Vγ9Vδ2 T cell recognition, playing an essential role in phosphoantigen sensing.
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