Search Results (947)

Many vertebrates have evolved resistance to snake venom as a result of coevolutionary chemical arms races. In Australian skinks (family Scincidae), who often encounter venomous elapid snakes, the frequency, diversity, and molecular basis of venom resistance have been unexplored. This study investigated the evolution of neurotoxin resistance in Australian skinks, focusing on mutations in the muscle nicotinic acetylcholine receptor (nAChR) α1 subunit’s orthosteric site that prevent pathophysiological binding by α-neurotoxins. We sampled a broad taxonomic range of Australian skinks and sequenced the nAChR α1 subunit gene. Key resistance-conferring mutations at the toxin-binding site (N-glycosylation motifs, proline substitutions, arginine insertions, changes in the electrochemical state of the receptor, and novel cysteines) were identified and mapped onto the skink organismal phylogeny. Comparisons with other venom-resistant taxa (amphibians, mammals, and reptiles) were performed, and structural modelling and binding assays were used to evaluate the impact of these mutations. Multiple independent origins of α-neurotoxin resistance were found across diverse skink lineages. Thirteen lineages evolved at least one resistance motif and twelve additional motifs evolved within these lineages, for a total of twenty-five times of α-neurotoxic venoms resistance. These changes sterically or electrostatically inhibit neurotoxin binding. Convergent mutations at the orthosteric site include the introduction of N-linked glycosylation sites previously known from animals as diverse as cobras and mongooses. However, an arginine (R) substitution at position 187 was also shown to have evolved on multiple occasions in Australian skinks, a modification previously shown to be responsible for the Honey Badger’s iconic resistance to cobra venom. Functional testing confirmed this mode of resistance in skinks. Our findings reveal that venom resistance has evolved extensively and convergently in Australian skinks through repeated molecular adaptations of the nAChR in response to the enormous selection pressure exerted by elapid snakes subsequent to their arrival and continent-wide dispersal in Australia. These toxicological findings highlight a remarkable example of convergent evolution across vertebrates and provide insight into the adaptive significance of toxin resistance in snake–lizard ecological interactions. Full article

The barbel chub (Squaliobarbus curriculus) exhibits remarkable resistance to grass carp reovirus (GCRV), a devastating pathogen in aquaculture. To reveal the molecular basis of this resistance, we investigated complement factor D (DF)—a rate-limiting serine protease governing alternative complement pathway activation. Molecular cloning revealed that the barbel chub DF (ScDF) gene encodes a 1251-bp cDNA sequence translating into a 250-amino acid protein. Crucially, bioinformatic characterization identified a unique N-glycosylation site at Asn¹³⁹ in ScDF, representing a structural divergence absent in grass carp (Ctenopharyngodon idella) DF (CiDF). While retaining a conserved Tryp_SPc domain harboring the catalytic triad (His⁶¹, Asp¹⁰⁹, and Ser²⁰⁴) and substrate-binding residues (Asp¹⁹⁸, Ser²¹⁹, and Gly²²¹), sequence and phylogenetic analyses confirmed ScDF’s evolutionary conservation, displaying 94.4% amino acid identity with CiDF and clustering within the Cyprinidae. Expression profiling revealed constitutive ScDF dominance in the liver, and secondary prominence was observed in the heart. Upon GCRV challenge in S. curriculus kidney (SCK) cells, ScDF transcription surged to a 438-fold increase versus uninfected controls at 6 h post-infection (hpi; p < 0.001)—significantly preceding the 168-hpi response peak documented for CiDF in grass carp. Functional validation showed that ScDF overexpression suppressed key viral capsid genes (VP2, VP5, and VP7) and upregulated the interferon regulator IRF9. Moreover, recombinant ScDF protein incubation induced interferon pathway genes and complement C3 expression. Collectively, ScDF’s rapid early induction (peaking at 6 hpi) and multi-pathway coordination may contribute to barbel chub’s GCRV resistance. These findings may provide molecular insights into the barbel chub’s high GCRV resistance compared to grass carp and novel perspectives for anti-GCRV breeding strategies in fish. Full article

Although Hylocereus polyrhizus pulp residues polysaccharides (HPPP) have shown potential in improving metabolic disorders and intestinal barrier function, the mechanism by which they exert their effects through regulating O-glycosylation modifications in the mucus layer remains unclear. Therefore, this study established a HFD-induced obese colitis mouse model (n = 5 per group) and combined nano-capillary liquid chromatography-tandem mass spectrometry (nanoLC-MS/MS) technology to quantitatively analyze the dynamic changes in O-glycosylation. Additionally, through quantitative O-glycosylation proteomics and whole-proteome analysis, we identified 155 specifically altered O-glycosylation sites in colon tissue, with the glycosylation modification level of the MUC2 core protein increased by approximately 2.1-fold. The results indicate that HPPP alleviates colonic mucosal damage by regulating interactions between mucus O-glycosylation. Overall, we demonstrated that HPPP increases HFD-induced O-glycosylation sites, improves intestinal mucosal structure in obese mice, and provides protective effects against obesity-induced intestinal mucosal damage. Full article

Multivalent lectin–glycan interactions (MLGIs) are vital for viral infection, cell-cell communication and regulation of immune responses. Their structural and biophysical data are thus important, not only for providing insights into their underlying mechanisms but also for designing potent glycoconjugate therapeutics against target MLGIs. However, such information remains to be limited for some important MLGIs, significantly restricting the research progress. We have recently demonstrated that functional nanoparticles, including ∼4 nm quantum dots and varying sized gold nanoparticles (GNPs), densely glycosylated with various natural mono- and oligo- saccharides, are powerful biophysical probes for MLGIs. Using two important viral receptors, DC-SIGN and DC-SIGNR (together denoted as DC-SIGN/R hereafter), as model multimeric lectins, we have shown that α-mannose and α-manno-α-1,2-biose (abbreviated as Man and DiMan, respectively) coated GNPs not only can provide sensitive measurement of MLGI affinities but also reveal critical structural information (e.g., binding site orientation and mode) which are important for MLGI targeting. In this study, we produced mannuronic acid (ManA) coated GNPs (GNP-ManA) of two different sizes to probe the effect of glycan modification on their MLGI affinity and antiviral property. Using our recently developed GNP fluorescence quenching assay, we find that GNP-ManA binds effectively to both DC-SIGN/R and increasing the size of GNP significantly enhances their MLGI affinity. Consistent with this, increasing the GNP size also significantly enhances their ability to block DC-SIGN/R-augmented virus entry into host cells. Particularly, ManA coated 13 nm GNP potently block Ebola virus glycoprotein-driven entry into DC-SIGN/R-expressing cells with sub-nM levels of EC₅₀. Our findings suggest that GNP-ManA probes can act as a useful tool to quantify the characteristics of MLGIs, where increasing the GNP scaffold size substantially enhances their MLGI affinity and antiviral potency. Full article

The Pelargonium genus, encompassing over 280 species, remains markedly underexplored despite extensive traditional use for respiratory, gastrointestinal, and dermatological disorders. This review of aqueous, alcoholic, and hydroalcoholic extracts reveals critical research gaps: only 10 species have undergone chemical characterization, while 17 have been evaluated for biological activities. Phytochemical analysis identified 252 unique molecules across all studies, with flavonoids emerging as the predominant class (n = 108). Glycosylated derivatives demonstrated superior bioactivity profiles compared to non-glycosylated analogs. Phenolic acids (n = 43) and coumarins (n = 31) represented additional major classes. Experimental studies primarily documented antioxidant, antibacterial, and anti-inflammatory effects, with emerging evidence for antidiabetic, anticancer, and hepatoprotective activities. However, methodological heterogeneity across studies limits comparative analysis and comprehensive understanding. In silico target prediction analysis was performed on 197 high-confidence molecular structures. Glycosylated flavonols, anthocyanidins, flavones, and coumarins showed strong predicted interactions with key inflammatory targets (ALOX15, ALOX5, PTGER4, and NOS2) and metabolic regulators (GSK3A and PI4KB), providing mechanistic support for observed therapeutic effects and suggesting potential applications in chronic inflammatory and metabolic diseases. These findings underscore the substantial therapeutic potential of underexplored Pelargonium species and advocate for systematic research employing untargeted metabolomics, standardized bioassays, and compound-specific mechanistic validation to fully unlock the pharmacological potential of this diverse genus. Full article

We conducted systematic glycomic and glycoproteomic profiling to characterize the dynamic N-glycosylation landscape of rat serum, with particular focus on sex- and time-dependent variations. MALDI-TOF-MS analysis revealed that rat serum N-glycans are predominantly biantennary, disialylated complex-type structures with extensive O-acetylation of Neu5Ac residues, especially in females. LC-MS/MS-based glycoproteomic analysis of albumin/IgG-depleted serum identified 87 glycoproteins enriched in protease inhibitors (e.g., serine protease inhibitor A3K) and immune-related proteins such as complement C3. Temporal analyses revealed stable sialylation in males but pronounced daily fluctuations in females, suggesting hormonal influence. Neu5Gc-containing glycans were rare and mainly derived from residual IgG, as confirmed by glycomic analysis. In contrast to liver-derived glycoproteins, purified IgG exhibited Neu5Gc-only sialylation without O-acetylation, underscoring distinct sialylation profiles characteristic of B cell-derived glycoproteins. Region-specific glycosylation patterns were observed in IgG, with the Fab region carrying more disialylated structures than Fc. These findings highlight cell-type and sex-specific differences in sialylation patterns between hepatic and immune tissues, with implications for hormonal regulation and biomarker research. This study provides a valuable dataset on rat serum glycoproteins and underscores the distinctive glycosylation features of rats, reinforcing their utility as model organisms in glycobiology and disease research. Full article

The Akabane virus (AKAV) is a significant member of the Orthobunyavirus genus, with its envelope glycoprotein Gc, focusing on its molecular structural features, immunoregulatory mechanisms, and application value in pathogen diagnosis and vaccine design. As a key structural protein of AKAV, Gc mediates virus adsorption and neutralizing antibody recognition through the N-terminal highly variable region (HVR), while the C-terminal conserved region (CR) dominates the membrane fusion process, and its glycosylation modification has a significant regulatory effect on protein function. In clinical diagnostics, serological assays based on Gc proteins (e.g., ELISA, immunochromatographic test strips) have been standardized; in vaccine development, the neutralizing epitope of Gc proteins has become a core target for subunit vaccine design. Follow-up studies were deeply needed to analyze the structure-function interaction mechanism of Gc proteins to provide theoretical support for the construction of a new type of AKAV prevention and control system. Full article

Equine lutropin hormone/choriogonadotropin receptor (LH/CGR) is a G protein-coupled receptor that binds to both luteinizing hormone and choriogonadotropin, with multiple potential N-linked glycosylation sites in the long extracellular domain region. The roles of these glycosylation sites in hormone binding have been widely studied; however, their relationships with cyclic adenosine monophosphate (cAMP) activation, loss of cell surface receptors, and phosphorylated extracellular signal-regulated kinases1/2 (pERK1/2) expression are unknown. We used site-directed mutagenesis with the substitution of Asn for Gln to alter the consensus sequences for N-linked glycosylation, and cAMP signaling was analyzed in the mutants. Specifically, the N174Q and N195Q mutants exhibited markedly reduced expression levels, reaching approximately 15.3% and 2.5%, respectively, of that observed for wild-type equine LH/CGR. Correspondingly, the cAMP EC₅₀ values were decreased by 7.6-fold and 5.6-fold, respectively. Notably, the N195Q mutant displayed an almost complete loss of cAMP activity, even at high concentrations of recombinant eCG, suggesting a critical role for this glycosylation site in receptor function. Despite these alterations, Western blot analysis revealed that pERK1/2 phosphorylation peaked at 5 min following agonist stimulation across all mutants, indicating that the ERK1/2 signaling pathway remains functionally intact. This study demonstrates that the specific N-linked glycosylation site, N195, in equine LH/CGR is indispensable for cAMP activity but is normally processed in pERK1/2 signaling. Thus, we suggest that in equine LH/CGR, agonist treatment induces biased signaling, differentially activating cAMP signaling and the pERK1/2 pathway. Full article

Scavenging domestic ducks significantly contribute to the transmission and maintenance of highly pathogenic H5N1 clade 2.3.4.4b avian influenza viruses in Bangladesh, a strain of growing global concern due to its broad host range, high pathogenicity, and spillover potential. This study investigates the molecular epidemiology and pathology of HPAI H5N1 viruses in unvaccinated scavenging ducks in Bangladesh, with the goal of assessing viral evolution and associated disease outcomes. Between June 2022 and March 2024, 40 scavenging duck flocks were investigated for HPAI outbreaks. Active HPAIV H5N1 infection was detected in 35% (14/40) of the flocks using RT-qPCR. Affected ducks exhibited clinical signs of incoordination, torticollis, and paralysis. Pathological examination revealed prominent meningoencephalitis, encephalopathy and encephalomalacia, along with widespread lesions in the trachea, lungs, liver, and spleen, indicative of systemic HPAIV infection. A phylogenetic analysis of full-genome sequences confirmed the continued circulation of clade 2.3.2.1a genotype G2 in these ducks. Notably, two samples of 2022 and 2023 harbored HPAIV H5N1 of clade 2.3.4.4b, showing genetic similarity to H5N1 strains circulating in Korea and Vietnam. A mutation analysis of the HA protein in clade 2.3.4.4b viruses revealed key substitutions, including T156A (loss of an N-linked glycosylation site), S141P (antigenic site A), and E193R/K (receptor-binding pocket), indicating potential antigenic drift and receptor-binding adaptation compared to clade 2.3.2.1a. The emergence of clade 2.3.4.4b with the first report of neurological and systemic lesions suggests ongoing viral evolution with increased pathogenic potential for ducks. These findings highlight the urgent need for enhanced surveillance and biosecurity to control HPAI spread in Bangladesh. Full article

Cholesterol stress profoundly modulates cellular processes, but its underlying mechanisms remain incompletely understood. To investigate cholesterol-responsive networks, we performed integrated transcriptome (RNA-seq) and metabolome (LC-MS) analyses on HeLa cells treated with cholesterol for 6 and 24 h. Through transcriptomic analysis of cholesterol-stressed HeLa cells, we identified stage-specific responses characterized by early-phase stress responses and late-phase immune-metabolic coordination. This revealed 1340 upregulated and 976 downregulated genes after a 6 h cholesterol treatment, including induction and suppression of genes involved in cholesterol efflux and sterol biosynthesis, respectively, transitioning to Nuclear Factor kappa-B (NF-κB) activation and Peroxisome Proliferator-Activated Receptor (PPAR) pathway modulation by 24 h. Co-expression network analysis prioritized functional modules intersecting with differentially expressed genes. We also performed untargeted metabolomics using cells treated with cholesterol for 6 h, which demonstrated extensive remodeling of lipid species. Interestingly, integrated transcriptomic and metabolic analysis uncovered GFPT1-driven Uridine Diphosphate-N-Acetylglucosamine (UDP-GlcNAc) accumulation and increased taurine levels. Validation experiments confirmed GFPT1 upregulation and ANGPTL4 downregulation through RT-qPCR and increased O-GlcNAcylation via Western blot. Importantly, clinical datasets further supported the correlations between GFPT1/ANGPTL4 expression and cholesterol levels in Non-Alcoholic Steatohepatitis (NASH) liver cancer patients. This work establishes a chronological paradigm of cholesterol sensing and identifies GFPT1 and ANGPTL4 as key regulators bridging glycosylation and lipid pathways, providing mechanistic insights into cholesterol-associated metabolic disorders. Full article

Narrative review synthesizes the most current literature on the SARS-CoV-2 XEC variant, focusing on its genomic evolution, immune evasion characteristics, epidemiological dynamics, and public health implications. To achieve this, we conducted a structured search of the literature of peer-reviewed articles, preprints, and official surveillance data from 2023 to early 2025, prioritizing virological, clinical, and immunological reports related to XEC and its parent lineages. Defined by the distinctive spike protein mutations, T22N and Q493E, XEC exhibits modest reductions in neutralization in vitro, although current evidence suggests that mRNA booster vaccines, including those targeting JN.1 and KP.2, retain cross-protective efficacy against symptomatic and severe disease. The XEC strain of SARS-CoV-2 has drawn particular attention due to its increasing prevalence in multiple regions and its potential to displace other Omicron subvariants, although direct evidence of enhanced replicative fitness is currently lacking. Preliminary analyses also indicated that glycosylation changes at the N-terminal domain enhance infectivity and immunological evasion, which is expected to underpin the increasing prevalence of XEC. The XEC variant, while still emerging, is marked by a unique recombination pattern and a set of spike protein mutations (T22N and Q493E) that collectively demonstrate increased immune evasion potential and epidemiological expansion across Europe and North America. Current evidence does not conclusively associate XEC with greater disease severity, although additional research is required to determine its clinical relevance. Key knowledge gaps include the precise role of recombination events in XEC evolution and the duration of cross-protective T-cell responses. New research priorities include genomic surveillance in undersampled regions, updated vaccine formulations against novel spike epitopes, and long-term longitudinal studies to monitor post-acute sequelae. These efforts can be augmented by computational modeling and the One Health approach, which combines human and veterinary sciences. Recent computational findings (GISAID, 2024) point to the potential of XEC for further mutations in under-surveilled reservoirs, enhancing containment challenges and risks. Addressing the potential risks associated with the XEC variant is expected to benefit from interdisciplinary coordination, particularly in regions where genomic surveillance indicates a measurable increase in prevalence. Full article

NGLY1 deficiency is a congenital disorder of deglycosylation, caused by pathogenic variants of the NGLY1 gene. It manifests as global developmental delay, hypo- or alacrima, hypotonia, and a primarily hyperkinetic movement disorder. The NGLY1 enzyme is involved in deglycosylation of misfolded N-glycosylated proteins before their proteasomal degradation and in the activation of transcription factors that control the expression of proteasomal subunits. Here, we have characterized the pathogenic NGLY1 variants found in three Swiss NGLY deficiency patients, as well as the most common pathogenic NGLY1 variant, Arg401*, found in about 20% of patients. Our functional and structural assessments of these variants show that they cause a profound reduction in NGLY1 activity, severely reduced expression of NGLY1 protein, and misprocessing of the transcription factor NFE2L1. Furthermore, transcription of proteasomal subunits and NGLY1 mRNA splicing are impaired by some of these variants. Our in silico structural analysis shows that the Arg390Gln substitution results in destabilization of NGLY1 structure due to a loss of an ionic interaction network of Arg390 and potentially impairment of protein–protein interactions. Our results provide important information on the functional and structural effects of pathogenic NGLY1 variants and pave the way for structure-based development of personalized treatment options. Full article

Peptidoglycan (PGN) is a component of bacterial cell walls; its fragments are recognized by the cytoplasmic receptors Nod1 and Nod2, thereby promoting the production of inflammatory cytokines and antibodies. To further elucidate these biological defense mechanisms, a large and stable supply of the PGN fragments via chemical synthesis is essential. However, the synthesis and purification of long PGN fragments are quite challenging due to their low solubility. In this study, we efficiently synthesized PGN fragments via solid-phase oligosaccharide synthesis (SPOS). Using the JandaJel™ Wang resin (JJ-Wang), an octasaccharide glycan chain of PGN was constructed by repeating glycosylation reactions to elongate β-1,4-linked disaccharide units composed of MurNAc and GlcNAc. To enhance reactivity, glycosylation was performed in a mixed solvent comprising C₄F₉OEt/CH₂Cl₂/THF with the intention of promoting substrate concentration onto the solid support through the fluorophobic effect, affording the PGN octasaccharide in a 19% overall yield (10 steps). Subsequently, after deprotection of the O-Fmoc, N-Troc, and ethyl ester groups, N- and O-acetylation proceeded smoothly, owing to the high swelling property of JJ-Wang. Peptide condensation with L-Ala-D-isoGln(OBn) and carboxylic acids was also achieved. Finally, cleavage of the PGN fragment from the resin with TFA afforded the desired octasaccharide with dipeptides in a 2.3% overall yield (15 steps). Full article

Momordica balsamina, a plant traditionally used in African medicine, contains a 30 kDa protein, MoMo30, previously identified by our group as an anti-HIV agent that binds glycan residues on the gp120 envelope protein, thereby acting as an entry inhibitor. In this study, we investigated whether prolonged exposure to MoMo30 exerts selective pressure on HIV-1 and induces mutations in the viral envelope (env) gene. T-lymphocyte cells were infected with HIV-1_NL4-3 and continuously treated with MoMo30 over a 24-day period. Viral RNA was isolated at regular intervals, and env genes were sequenced using the Illumina platform. RNA sequence variant calling was performed using iVar, which uses a frequency-based binomial test with a default allele frequency threshold of 3% and a minimum base quality of 20 and applies Bonferroni correction for multiple testing. The infectivity of the MoMo30-exposed virus was assessed using MAGI-CXCR4 cells, visualized by β-galactosidase staining, and compared to untreated controls. Statistical significance was determined via two-way ANOVA. MoMo30-treated HIV-1 exhibited multiple detrimental mutations in gp120 and gp41, including missense, nonsense, and frameshift changes. Notably, 32% of N-linked glycosylation sites were deleted in the treated virus, while no such changes were observed in controls. Functionally, the MoMo30-treated virus demonstrated a sixfold reduction in infectivity compared to untreated HIV-1_NL4-3. These findings suggest that MoMo30 imposes genetic pressure on HIV-1_NL4-3, selecting for mutations that reduce viral fitness. Full article

Glycans on the surface of all immune cells are the product of diverse post-translational modifications (glycosylation) that affect almost all proteins and possess enormous structural heterogeneity. Their bioinformational content is decoded by glycan-binding proteins (lectins, GBPs), such as C-type lectins, including selectins, galectins, and Siglecs. Glycans located on the surface of immune cells are involved in many immunological processes through interactions with GBPs. Lectins recognize changes in the glycan epitopes; distinguish among host (self), microbial (non-self), and tumor (modified self) antigens; and consequently regulate immune responses. Understanding GBP–glycan interactions accelerates the development of glycan-targeted therapeutics in severe diseases, including inflammatory and autoimmune diseases and cancer. This review will discuss N- and O-glycosylations and glycosyltransferases involved in the biosynthesis of carbohydrate epitopes and address how interactions between glycan epitopes and GBPs are crucial in immune responses. The pivotal role of the glycan antigen tetrasaccharide sialyl Lewis x in mediating immune and tumor cell trafficking into the extravascular site will be discussed. Next, the role of glycans in modulating bacterial, fungal, viral, and parasitic infections and cancer will be surveyed. Finally, the role of glycosylation in antibodies and carbohydrate vaccines will be analyzed. Full article