Engaging natural regulatory myeloid cells to restrict T-cell hyperactivation-induced liver inflammation via extracellular vesicle-mediated purine metabolism regulation.

Rationale: Dysregulated T-cell immune response-mediated inflammation plays critical roles in the pathology of diverse liver diseases, but the underlying mechanism of liver immune homeostasis control and the specific therapies for limiting T-cell overactivation remain unclear. Methods: The metabolic changes in concanavalin A (ConA) mice and autoimmune hepatitis (AIH) patients and their associations with liver injury were analyzed. The expression of purine catabolism nucleases (e.g., CD39 and CD73) on liver cells and immune cells was assessed. The effects of MCregs and their extracellular vesicles (EVs) on CD4+ T-cell overactivation and the underlying mechanism were also explored. Results: Our findings revealed significant alterations in purine metabolism in ConA mice and AIH patients, which correlated with liver injury severity and therapeutic response. CD39 and CD73 were markedly upregulated on CD11b+Gr-1+ MCs under liver injury conditions. The naturally expanded CD39+CD73+Gr-1highCD11b+ MCreg subset during early liver injury effectively suppressed CD4+ T-cell hyperactivation and liver injury both in vitro and in vivo. Mechanistically, MCregs released CD73high EVs, which converted extracellular AMP to immunosuppressive metabolites (e.g., adenosine and inosine), activating the cAMP pathway and inhibiting glycolysis and cytokine secretion in activated CD4+ T cells. Conclusions: This study provides insights into the mechanism controlling immune homeostasis during the early liver injury phase and highlights that MCreg or MCreg-EV therapy may be a specific strategy for preventing diverse liver diseases induced by T-cell overactivation.

Spontaneous and Stimulated Production of Cytokines by Blood Cells Ex Vivo as a Biomarker of Initially High or Low Hypoxia Resistance in Rats.

Spontaneous and stimulated production of cytokines by peripheral blood cells obtained from the caudal vein of male Wistar rats was assessed before testing their resistance to oxygen deficiency in a decompression chamber. To study the spontaneous production of cytokines, heparinized blood cells were incubated in a culture medium (24 h, 5% CO2, 37°C) and the content of proinflammatory cytokines IL-6 and TNFα and anti-inflammatory IL-10 in the culture medium was assessed by ELISA. To stimulate cytokine production, blood cells were incubated for 24 h with LPS, phytohemagglutinin, and concanavalin A at final concentrations of 2, 4, and 4 µg, respectively. Two weeks after blood sampling, individual resistance of the animals to hypoxia in a decompression chamber was determined. In animals with low resistance to hypoxia, the levels of spontaneous production of all three cytokines were significantly higher, while after stimulation, the level of IL-1ß increased by more than 2 times. The animals with spontaneous production of IL-10>50 pg/ml, IL-6>10 pg/ml, and TNFα>10 pg/ml, as well as with the increase in IL-1ß production by more than 2 times upon stimulation were classified as low-resistant. At IL-10<15 pg/ml, IL-6<9 pg/ml, and TNFα<7 pg/ml, as well as the absence of the increase in IL-1ß production upon stimulation, they were classified as high-resistant. The identified features of spontaneous and stimulated production of cytokines can be used as non-invasive biomarkers to determine the resistance to hypoxia without exposure to sublethal hypoxia in a decompression chamber.

The cytoplasmic-nuclear transport of DDX3X promotes immune-mediated liver injury in mice regulated by endoplasmic reticulum stress.

Immune-mediated liver injury is a common characteristic of various liver diseases, including autoimmune and viral hepatitis. Here, we investigated the role of DEAD-box helicase 3, X-linked (DDX3X) in immune-mediated liver injury. Liver injury was induced in C57BL/6J mice via concanavalin A (Con A). DDX3X hepatocyte-specific knockout (DDX3XΔHep) mice and control (DDX3Xfl/fl) mice were utilized to investigate the role of DDX3X in liver injury. Primary hepatocytes were treated with tunicamycin (TM) to induce ER stress in vitro. The expression of DDX3X in patients with various liver diseases was evaluated. Hepatic DDX3X expression increased, and DDX3X translocated from the cytoplasm to the nucleus during Con A-induced liver injury. DDX3X deficiency ameliorated mouse liver injury and reduced ER stress in liver tissue. The inhibition of ER stress with 4-PBA significantly attenuated liver injury while decreasing DDX3X levels in liver tissue. However, the upregulation of hepatic DDX3X expression reversed Con A-induced liver injury and negated the protective effect of 4-PBA. Mechanistically, the nuclear translocation of DDX3X promoted ER stress-induced apoptosis through the transcriptional induction of CHOP. Moreover, DDX3X was elevated and translocated into the nucleus in patients with HBV-LF and AIH. Additionally, serum DDX3X levels markedly increased in patients with HBV-LF, and a consistent decrease in DDX3X was associated with a good prognosis. The cytoplasmic-to-nuclear translocation of DDX3X promotes ER stress-induced apoptosis, which is an obligatory step that drives hepatic necrosis and tissue damage. Notably, DDX3X is a potential therapeutic target for immune-mediated liver injury.

Glycyrrhizic acid alleviates concanavalin A-induced acute liver injury by regulating monocyte-derived macrophages.

Autoimmune hepatitis (AIH) is characterized by persistent liver inflammation induced by aberrant immune responses. Glycyrrhizic acid (GA), a prominent bioactive ingredient of licorice, has shown potential as a safe and effective treatment for AIH. However, the immune regulatory mechanism by which GA exerts its therapeutic effect on AIH remains elusive. In this study, we found that GA intervention significantly alleviated ConA-induced acute liver injury in mice. Cytometry by time-of-flight (CyTOF) analysis revealed that GA increased the abundance of anti-inflammatory F4/80loCD11bhiMHCIIhi MoMF-1 and decreased the abundance of pro-inflammatory F4/80loCD11bhiiNOShi MoMF-3. Multiplex immunofluorescence demonstrated the infiltration of MoMFs in liver tissues. Single-cell RNA sequencing (scRNA-seq) analysis indicated that GA facilitated the immune activation in MoMFs, regulated gene expression of diverse cytokines secreted by MoMFs, and played a role in shaping the immune microenvironment. By integrating the results of CyTOF with scRNA-seq, our study comprehensively elucidates the immune landscape of ConA-induced liver injury following GA intervention, advancing the understanding of GA's mechanism of action. However, it is important to note that some single-cell data in this study remain raw and require further processing and annotation. Our findings suggest that GA alleviates ConA-induced acute liver injury by regulating the function of MoMFs, opening potential avenues for AIH treatment and management, and providing a theoretical basis for the design of novel MoMFs-centered immunotherapies.

Concanavalin-conjugated zinc-metal-organic framework drug for pH-controlled and targeted therapy of wound bacterial infection.

Wounds are prone to infection which may be fatal to the life of the patient. The use of antibiotics is essential for managing bacterial infections in wounds, but the long-term use of high doses of antibiotics may lead to bacterial drug resistance and even to creation of superbacteria. Therefore, the development of targeted antimicrobial treatment strategies and the reduction in antibiotic usage are of utmost urgency. In this study, a multifunctional nanodrug delivery system (Cef-rhEGF@ZIF-8@ConA) for the treatment of bacteriostatic infection was synthesized through self-assembly of Zn2+, cefradine (Cef) and recombinant human epidermal growth factor (rhEGF), then conjugated with concanavalin (ConA), which undergoes pH-responsive degradation to release the drugs. First, ConA can specifically combine with bacteria and inhibit the rapid release of Zn2+ ions, thus achieving a long-acting antibacterial effect. Cef exerts its antibacterial effect by inhibiting the synthesis of bacterial membrane proteins. Finally, Zn2+ ions released from the Zn-metal-organic framework (MOF) demonstrate bacteriostatic properties by enhancing the permeability of the bacterial cell membrane. Furthermore, rhEGF upregulates angiogenesis-associated genes, thereby promoting angiogenesis, re-epithelialization and wound healing processes. The results showed that Cef-rhEGF@ZIF-8@ConA has good biocompatibility, with antibacterial efficacy against Staphylococcus aureus and Escherichia coli of 99.61 % and 99.75 %, respectively. These nanomaterials can inhibit the release of inflammatory cytokines and promote the release of anti-inflammatory cytokines, while also stimulating the proliferation of fibroblasts to facilitate wound healing. Taken together, the Cef-rhEGF@ZIF-8@ConA nanosystem is an excellent candidate in clinical therapeutics for bacteriostatic infection and wound healing.

Concanavalin-A-Induced Acute Liver Injury in Mice.

Acute liver injury is a life-threatening disease. Although immune responses are involved in the development and exacerbation of acute liver injury, the cellular and molecular mechanisms are not fully understood. Intravenous administration of the plant lectin concanavalin A (ConA) is widely used as a model of acute liver injury. ConA triggers T cell activation and cytokine production by crosslinking glycoproteins, including the T cell receptor, leading to the infiltration of myeloid cells into the liver and the subsequent amplification of inflammation in the liver. Thus, the pathogenesis of ConA-induced acute liver injury is considered a model of immune-mediated acute liver injury or autoimmune hepatitis in humans. However, the severity of the liver injury and the analyses of immune cells and non-hematopoietic cells in the liver following ConA injection are significantly influenced by the experimental conditions. This article outlines protocols for ConA-induced acute liver injury in mice and evaluation methods for liver injury, immune cells, and non-hematopoietic cells in the liver. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Induction of acute liver injury by ConA injection Basic Protocol 2: Evaluation of inflammatory cytokines in mouse plasma Basic Protocol 3: Preparation of liver sections and histological analysis of liver injury Basic Protocol 4: Preparation of liver immune cells Basic Protocol 5: Preparation of hepatocytes, endothelial cells, and hepatic stellate cells Basic Protocol 6: Flow cytometry of immune and non-hematopoietic liver cells Basic Protocol 7: Flow cytometric sorting of endothelial cells and hepatic stellate cells Basic Protocol 8: Quantitative reverse transcription polymerase chain reaction.

[Effect of Collagen Peptides on Function of Mouse T Lymphocytes under Simulated Microgravity].

OBJECTIVE: To understand the effect of collagen peptides on the function of mouse lymphocytes under simulated microgravity. METHODS: The splenocytes of mice were isolated, and the rotary cell culture system was used to simulate the microgravity. The T lymphocytes were stimulated with mitotic agents, concanavalin A (ConA), and the cells were treated with different concentrations of collagen peptides. The proliferation of lymphocytes and the levels of cytokines in the supernatant were detected. RESULTS: Simulated microgravity could inhibit the proliferation of spleen T lymphocytes and decrease the level of cytokines in the supernatant. Collagen peptides could promote the lymphocyte proliferation and cytokine production in cells cultured under simulated microgravity. CONCLUSION: Collagen peptides may attenuate the inhibitory effect of simulated microgravity on T lymphocytes by regulating the cell proliferation and the secretion of cytokines.

FKBP38 deletion exacerbates ConA-induced hepatitis by promoting the immune response through the MCP-1/p38 pathway.

Autoimmune hepatitis (AIH) is a chronic liver disease characterized by immune dysregulation and hepatocyte damage. FKBP38, a member of the immunophilin family, has been implicated in immune regulation and the modulation of intracellular signaling pathways; however, its role in AIH pathogenesis remains poorly understood. In this study, we aimed to investigate the effects of hepatic FKBP38 deletion on AIH using a hepatic FKBP38 knockout (LKO) mouse model created via cre-loxP technology. We compared the survival rates, incidence, and severity of AIH in LKO mice with those in control mice. Our findings revealed that hepatic FKBP38 deletion resulted in an unfavorable prognosis in LKO mice with AIH. Specifically, LKO mice exhibited heightened liver inflammation and extensive hepatocyte damage compared to control mice, with a significant decrease in anti-apoptotic proteins and a marked increase in pro-apoptotic proteins. Additionally, transcriptional and translational levels of pro-inflammatory cytokines and chemokines were significantly increased in LKO mice compared to control mice. Immunoblot analysis showed that MCP-1 expression was significantly elevated in LKO mice. Furthermore, the phosphorylation of p38 was increased in LKO mice with AIH, indicating that FKBP38 deletion promotes liver injury in AIH by upregulating p38 phosphorylation and increasing MCP-1 expression. Immune cell profiling demonstrated elevated populations of T, NK, and B cells, suggesting a dysregulated immune response in LKO mice with AIH. Overall, our findings suggest that FKBP38 disruption exacerbates AIH severity by augmenting the immune response by activating the MCP-1/p38 signaling pathway.

An Improved Diabatization Scheme for Computing the Electronic Circular Dichroism of Proteins.

We advance the quality of first-principles calculations of protein electronic circular dichroism (CD) through an amelioration of a key deficiency of a previous procedure that involved diabatization of electronic states on the amide chromophore (to obtain interamide couplings) in a ß-strand conformation of a diamide. This yields substantially improved calculated far-ultraviolet (far-UV) electronic circular dichroism (CD) spectra for ß-sheet conformations. The interamide couplings from the diabatization procedure for 13 secondary structural elements (13 diamide structures) are applied to compute the CD spectra for seven example proteins: myoglobin (α helix), jacalin (ß strand), concanavalin A (ß type I), elastase (ß type II), papain (α + ß), 310-helix bundle (310-helix) and snow flea antifreeze protein (polyproline). In all cases, except concanavalin A and papain, the CD spectra computed using the interamide couplings from the diabatization procedure yield improved agreement with experiment with respect to previous first-principles calculations.

Knockout of C6orf120 in Rats Alleviates Concanavalin A-induced Autoimmune Hepatitis by Regulating Macrophage Polarization.

Objective: The effect of the functionally unknown gene C6orf120 on autoimmune hepatitis was investigated on C6orf120 knockout rats ( C6orf120 -/- ) and THP-1 cells. Method: Six-eight-week-old C6orf120 -/- and wild-type (WT) SD rats were injected with Con A (16 mg/kg), and euthanized after 24 h. The sera, livers, and spleens were collected. THP-1 cells and the recombinant protein (rC6ORF120) were used to explore the mechanism in vitro. The frequency of M1 and M2 macrophages was analyzed using flow cytometry. Western blotting and PCR were used to detect macrophage polarization-associated factors. Results: C6orf120 knockout attenuated Con A-induced autoimmune hepatitis. Flow cytometry indicated that the proportion of CD68 +CD86 +M1 macrophages from the liver and spleen in the C6orf120 -/- rats decreased. C6orf120 knockout induced downregulation of CD86 protein and the mRNA levels of related inflammatory factors TNF-α, IL-1ß, and IL-6 in the liver. C6orf120 knockout did not affect the polarization of THP-1 cells. However, rC6ORF120 promoted the THP-1 cells toward CD68 +CD80 +M1 macrophages and inhibited the CD68 +CD206 +M2 phenotype. Conclusion: C6orf120 knockout alleviates Con A-induced autoimmune hepatitis by inhibiting macrophage polarization toward M1 macrophages and reducing the expression of related inflammatory factors in C6orf120 -/- rats.

Concanavalin A, lectin from Canavalia ensiformis seeds has Leishmania infantum antipromastigote activity mediated by carbohydrate recognition domain.

Leishmaniases, caused by Leishmania parasites, are widespread and pose significant health risks globally. Visceral leishmaniasis (VL) is particularly prevalent in Brazil, with high morbidity and mortality rates. Traditional treatments, such as pentavalent antimonials, have limitations due to toxicity and resistance. Therefore, exploring new compounds like lectins is crucial. Concanavalin A (ConA) has shown promise in inhibiting Leishmania growth. This study aimed to evaluate its leishmanicidal effect on L. infantum promastigotes and understand its mechanism of action. In vitro tests demonstrated inhibition of promastigote growth when treated with ConA, with IC50 values ranging from 3 to 5 µM over 24-72 h. This study suggests that ConA interacts with L. infantum glycans. Additionally, ConA caused damage to the membrane integrity of parasites and induced ROS production, contributing to parasite death. Scanning electron microscopy confirmed morphological alterations in treated promastigotes. ConA combined with the amphotericin B (AmB) showed synergistic effects, reducing the required dose of AmB, and potentially mitigating its toxicity. ConA demonstrated no cytotoxic effects on macrophages, instead stimulating their proliferation. These findings reinforce that lectin exhibits promising leishmanicidal activity against L. infantum promastigotes, making ConA a potential candidate for leishmaniasis treatment.

Quantum dots as a fluorescent labeling tool for live-cell imaging of Leptospira.

Leptospirosis is a global public health problem caused by Gram-negative pathogenic bacteria belonging to the genus Leptospira. The disease is transmitted through the urine of infected animals, which contaminates water and soil, leading to the infection of other animals and humans. Currently, several approaches exist to detect these bacteria; however, a new sensitive method for the live-cell imaging of Leptospira is required. In this study, we report the green synthesis of cadmium telluride quantum dots (CdTe QDs) which are unique fluorescent nanocrystals with a high fluorescence quantum yield capable of modifying cell surfaces and are biocompatible with cells. The fabrication of QDs with concanavalin A (ConA), a carbohydrate-binding lectin and known biological probe for Gram-negative bacteria, produced ConA-QDs which can effectively bind on Leptospira and exhibit strong fluorescence under simple fluorescence microscopy, allowing the live-cell imaging of the bacteria. Overall, we performed the simple synthesis of ConA-QDs and demonstrated their potential use as versatile fluorescent probes for the live-cell imaging of Leptospira. This technique could be further applied to track leptospiral cells and study the infection mechanism, contributing to a more thorough understanding of leptospirosis and how to control it in the future.

New bioelectrode based on graphene quantum dots-polypyrrole film and Concanavalin A for pathogenic microorganism detection.

Infections caused by microorganisms are a public health problem worldwide. New biodetection systems are essential to diagnose with accuracy resulting in more effective treatment. In this work, we propose a ConA-conjugated graphene quantum dots and polypyrrole film-based biosensor for label-free detection of Candida albicans, Candida glabrata, Candida tropicalis, E. coli, B. subitilis, and S. aureus. We modified polypyrrole and graphene quantum dots (PPY-QDGs) with Concanavalin A (Con A) lectin. ConA is a glucose/mannose-specific lectin. The results showed that ConA lectin has the highest binding affinity for C. tropicalis and S. subtilis. PPY-GQDs-ConA binding profile revealed differential response for Candida spp (C. tropicalis > C. albicans > C. glabrata) and bacterial (B. subtilis > S. aureus > E. coli). The limits of detection (LOD) obtained were 1.42 CFU/mL for C. albicans, and 3.72 CFU/mL for C. glabrata. C. tropicalis yielded a LOD of 0.18 CFU/mL. The respective LODs for the evaluated bacteria were 0.39 CFU/mL for S. aureus, 0.72 CFU/mL for S. subtilis, and 2.63 CFU/mL for E. coli. The differential response obtained for the sensor can be attributed to the heterogeneous distribution of carbohydrates on the microorganism's surfaces. The proposed system based on a flexible substrate is effective for microbiological diagnosis.

Concanavalin A-assisted multiplex digital PCR assay for rapid capture and accurate quantification detection of foodborne pathogens.

Multiplex, sensitive, and rapid detection of pathogens is crucial for ensuring food safety and safeguarding human health, however, it remains a significant challenge. This study proposes a concanavalin A-assisted multiplex digital amplification (CAMDA) assay for simultaneous quantitative detection of multiple foodborne bacteria. The CAMDA assay enables the simultaneous detection of six foodborne pathogens within 1.1 h and the limit of detection is 101 CFU/mL. Furthermore, the CAMDA assay exhibits high specificity, with a rate of 97 % for Bacillus cereus and 100 % for other pathogens tested in this study. Moreover, practical application validation using eight milk powder samples demonstrates that the accuracy of the CAMDA assay reaches 100 % when compared to qPCR results. Therefore, our developed CAMDA assay holds great potential for accurate and rapid detection of multiple pathogens in complex food matrices while also promoting the utilization of microfluidic chips in food investigation.

Concanavalin A Delivers a Photoactive Protein to the Bacterial Wall.

Modular supramolecular complexes, where different proteins are assembled to gather targeting capability and photofunctional properties within the same structures, are of special interest for bacterial photodynamic inactivation, given their inherent biocompatibility and flexibility. We have recently proposed one such structure, exploiting the tetrameric bacterial protein streptavidin as the main building block, to target S. aureus protein A. To expand the palette of targets, we have linked biotinylated Concanavalin A, a sugar-binding protein, to a methylene blue-labelled streptavidin. By applying a combination of spectroscopy and microscopy, we demonstrate the binding of Concanavalin A to the walls of Gram-positive S. aureus and Gram-negative E. coli. Photoinactivation is observed for both bacterial strains in the low micromolar range, although the moderate affinity for the molecular targets and the low singlet oxygen yields limit the overall efficiency. Finally, we apply a maximum entropy method to the analysis of autocorrelation traces, which proves particularly useful when interpreting signals measured for diffusing systems heterogeneous in size, such as fluorescent species bound to bacteria.

Effects of A1 Milk, A2 Milk and the Opioid-like Peptide ß-Casomorphin-7 on the Proliferation of Human Peripheral Blood Mononuclear Cells.

Special attention is given to cow's milk and its variants, with ongoing discussions about health-related impacts primarily focusing on the A1 variant in contrast to the A2 variant. The difference between these variants lies in a single amino acid alteration at position 67 of ß-casein. This alteration is presumed to make the A1 variant more susceptible to enzymatic breakdown during milk digestion, leading to an increased release of the peptide ß-casomorphin-7 (BCM-7). BCM-7 is hypothesized to interact with µ-opioid receptors on immune cells in humans. Although BCM-7 has demonstrated both immunosuppressive and inflammatory effects, its direct impact on the immune system remains unclear. Thus, we examined the influence of A1 and A2 milk on Concanavalin A (ConA)-stimulated human peripheral blood mononuclear cells (PBMCs), as well as the effect of experimentally digested A1 and A2 milk, containing different amounts of free BCM-7 from ß-casein cleavage. Additionally, we evaluated the effects of pure BCM-7 on the proliferation of ConA-stimulated PBMCs and purified CD4+ T cells. Milk fundamentally inhibited PBMC proliferation, independent of the ß-casein variant. In contrast, experimentally digested milk of both variants and pure BCM-7 showed no influence on the proliferation of PBMCs or isolated CD4+ T cells. Our results indicate that milk exerts an anti-inflammatory effect on PBMCs, regardless of the A1 or A2 ß-casein variant, which is nullified after in vitro digestion. Consequently, we deem BCM-7 unsuitable as a biomarker for food-induced inflammation.

Siglec-H-/- Plasmacytoid Dendritic Cells Protect Against Acute Liver Injury by Suppressing IFN-γ/Th1 Response and Promoting IL-21+ CD4 T Cells.

BACKGROUND & AIMS: Siglec-H is a receptor specifically expressed in mouse plasmacytoid dendritic cells (pDCs), which functions as a negative regulator of interferon-α production and plays a critical role in pDC maturation to become antigen-presenting cells. The function of pDCs in autoimmune and inflammatory diseases has been reported. However, the effect of Siglec-H expression in pDCs in liver inflammation and diseases remains unclear. METHODS: Using the model of concanavalin A-induced acute liver injury (ALI), we investigated the Siglec-H/pDCs axis during ALI in BDCA2 transgenic mice and Siglec-H-/- mice. Anti-BDCA2 antibody, anti-interleukin (IL)-21R antibody, and Stat3 inhibitor were used to specifically deplete pDCs, block IL21 receptor, and inhibit Stat3 signaling, respectively. Splenocytes and purified naive CD4 T cells and bone marrow FLT3L-derived pDCs were cocultured and stimulated with phorbol myristate acetate/ionomycin and CD3/CD28 beads, respectively. RESULTS: Data showed that specific depletion of pDCs aggravated concanavalin A-induced ALI. Remarkably, alanine aminotransferase, hyaluronic acid, and proinflammatory cytokines IL6 and tumor necrosis factor-α levels were lower in the blood and liver of Siglec-H knockout mice. This was associated with attenuation of both interferon-γ/Th1 response and Stat1 signaling in the liver of Siglec-H knockout mice while intrahepatic IL21 and Stat3 signaling pathways were upregulated. Blocking IL21R or Stat3 signaling in Siglec-H knockout mice restored concanavalin A-induced ALI. Finally, we observed that the Siglec-H-null pDCs exhibited immature and immunosuppressive phenotypes (CCR9LowCD40Low), resulting in reduction of CD4 T-cell activation and promotion of IL21+CD4 T cells in the liver. CONCLUSIONS: During T-cell-mediated ALI, Siglec-H-null pDCs enhance immune tolerance and promote IL21+CD4 T cells in the liver. Targeting Siglec-H/pDC axis may provide a novel approach to modulate liver inflammation and disease.

Tailoring Metallosupramolecular Glycoassemblies for Enhancing Lectin Recognition.

Multivalency is a fundamental principle in nature that leads to high-affinity intermolecular recognition through multiple cooperative interactions that overcome the weak binding of individual constituents. For example, multivalency plays a critical role in lectin-carbohydrate interactions that participate in many essential biological processes. Designing high-affinity multivalent glycoconjugates that engage lectins results in systems with the potential to disrupt these biological processes, offering promising applications in therapeutic design and bioengineering. Here, a versatile and tunable synthetic platform for the synthesis of metallosupramolecular glycoassemblies is presented that leverages subcomponent self-assembly, which employs metal ion templates to generate complex supramolecular architectures from simple precursors in one pot. Through ligand design, this approach provides precise control over molecular parameters such as size, shape, flexibility, valency, and charge, which afforded a diverse family of well-defined hybrid glyconanoassemblies. Evaluation of these complexes as multivalent binders to Concanavalin A (Con A) by isothermal titration calorimetry (ITC) demonstrates the optimal saccharide tether length and the effect of electrostatics on protein affinity, revealing insights into the impact of synthetic design on molecular recognition. The presented studies offer an enhanced understanding of structure-function relationships governing lectin-saccharide interactions at the molecular level and guide a systematic approach towards optimizing glyconanoassembly binding parameters.

Glyco-DNA: Enzymatic Synthesis of Base-Modified and Hypermodified DNA Displaying up to Four Different Monosaccharide Units in the Major Groove.

A portfolio of six modified 2'-deoxyribonucleoside triphosphate (dNTP) derivatives derived from 5-substituted pyrimidine or 7-substituted 7-deazapurine bearing different carbohydrate units (d-glucose, d-galactose, d-mannose, l-fucose, sialic acid and N-Ac-d-galactosamine) tethered through propargyl-glycoside linker was designed and synthesized via the Sonogashira reactions of halogenated dNTPs with the corresponding propargyl-glycosides. The nucleotides were found to be good substrates for DNA polymerases in enzymatic primer extension and PCR synthesis of modified and hypermodified DNA displaying up to four different sugars. Proof of concept binding study of sugar-modified oligonucleotides with concanavalin A showed positive effect of avidity and sugar units count.

Kainate receptor channel opening and gating mechanism.

Kainate receptors, a subclass of ionotropic glutamate receptors, are tetrameric ligand-gated ion channels that mediate excitatory neurotransmission1-4. Kainate receptors modulate neuronal circuits and synaptic plasticity during the development and function of the central nervous system and are implicated in various neurological and psychiatric diseases, including epilepsy, depression, schizophrenia, anxiety and autism5-11. Although structures of kainate receptor domains and subunit assemblies are available12-18, the mechanism of kainate receptor gating remains poorly understood. Here we present cryo-electron microscopy structures of the kainate receptor GluK2 in the presence of the agonist glutamate and the positive allosteric modulators lectin concanavalin A and BPAM344. Concanavalin A and BPAM344 inhibit kainate receptor desensitization and prolong activation by acting as a spacer between the amino-terminal and ligand-binding domains and a stabilizer of the ligand-binding domain dimer interface, respectively. Channel opening involves the kinking of all four pore-forming M3 helices. Our structures reveal the molecular basis of kainate receptor gating, which could guide the development of drugs for treatment of neurological disorders.