Search Results (128)

Endometriosis (EM) is a chronic inflammatory disease characterized by the growth of endometrial-like tissue outside the uterus, yet its molecular mechanisms remain poorly understood. This study investigated the expression of mucins (MUC1, MUC2, MUC5AC, MUC6, MUC16) and their O-glycans in endometriotic lesions, given their roles in epithelial protection, adhesion, and immune modulation. Using immunohistochemistry, Western blotting, lectin profiling, histochemical staining, and transcriptomic analysis, we compared mucin levels and glycosylation patterns in eutopic and ectopic tissues from women with and without endometriosis and measured mucin-derived tumor markers in serum (CA 125/MUC16 and CA 15-3/MUC1) and peritoneal fluid (CA 125/MUC16). The results showed significant upregulation of all mucins in EM biopsies, with increased MUC1 transcript levels, while MUC6 and MUC16 protein levels did not always align with transcripts. Yet, tumor markers CA 125 and CA 15-3 showed no significant differences between groups. Looking at mucin distribution in biopsies of peritoneal (pEM), deep infiltrating and ovarian EM, MUC1 was significantly overexpressed in lesions of all EM forms, while MUC5AC was significantly elevated in pEM. Lectin analysis revealed specific glycan changes, including elevated core-1 O-glycans and α(1-2)-linked fucosylation, while sialylation remained unchanged. These findings demonstrate consistent mucin dysregulation and glycan alterations, implicating their roles in epithelial adhesion, immune evasion, and lesion persistence. Mucin biology thus emerges as a promising target for diagnostic and therapeutic strategies in endometriosis. Full article

Alzheimer’s disease (AD) is the most prevalent cause of dementia, characterized by progressive cognitive decline, amyloid-β (Aβ) plaques, and neurofibrillary tangles composed of hyperphosphorylated tau protein. Other tauopathies, including frontotemporal lobar degeneration (FTLD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD) share pathological hallmarks centered on abnormal tau biology. Increasing evidence highlights the role of post-translational modifications in modulating these pathogenic processes. Among these, glycosylation, the enzymatic attachment of glycans to proteins or lipids, has emerged as a critical regulator of protein folding, trafficking, aggregation, and clearance. Both N-linked glycosylation (N-glycosylation) and O-linked glycosylation (O-glycosylation) influence tau stability, Aβ processing, receptor signaling, synaptic integrity, and neuroinflammation. Dysregulated glycosylation patterns have been documented in brains and cerebrospinal fluid (CSF) of AD patients, suggesting biomarker potential and novel therapeutic targets. Moreover, glycosyltransferases and glycosidases show altered expression in neurodegeneration, linking metabolic and inflammatory pathways to tauopathy progression. This review synthesizes current evidence on the implications and consequences of glycosylation in AD and other tauopathies, integrating mechanistic, pathological, and clinical findings. We also discuss advances in glycoproteomics, the interplay between glycosylation and phosphorylation, and the translational potential of targeting glycosylation pathways for diagnosis and therapy. Full article

Background: Pancreatic ductal adenocarcinoma (PDAC) exhibits marked resistance to immunotherapy. Beyond its characteristically low tumor mutational burden, post-translational modifications (PTMs) remodel the immunopeptidome and promote immune escape through reversible, enzyme-driven programs. Subject Matter: We synthesize evidence that aberrant glycosylation, O-GlcNAcylation, phosphorylation, and citrullination constitute core determinants of antigen visibility operating within spatially discrete tumor niches and a desmoplastic stroma. In hypoxic regions, HIF-linked hexosamine metabolism and OGT activity stabilize immune checkpoints and attenuate antigen processing; at tumor margins, sialylated mucins engage inhibitory Siglec receptors on innate and adaptive lymphocytes; within the stroma, PAD4-dependent NET formation enforces T cell exclusion. We also delineate technical barriers to discovering PTM antigens labile chemistry, low stoichiometry, and method-embedded biases and outline practical solutions: ETD/EThcD/AI-ETD fragmentation, PTM-aware database searching and machine-learning models, and autologous validation in patient-derived organoid–T cell co-cultures. Finally, we highlight therapeutic strategies that either immunize against PTM neoepitopes or inhibit PTM machinery (e.g., PAD4, OGT, ST6GAL1), with stromal remodeling as an enabling adjunct. Conclusions: PTM biology, spatial omics, and patient sample models can uncover targetable niches and speed up PDAC vaccination, TCR, and enzyme-directed treatment development. Full article

Post-translational modifications (PTMs) are critically important for protein structure and function, with glycosylation being one of the most common forms of PTM. The gastric pathogen Helicobacter pylori has a general glycosylation system, which performs complex glycosylation of lipopolysaccharide, flagella proteins, and outer membrane proteins (OMPs). One of the best-described OMPs of H. pylori is the blood group binding adhesin (BabA), which interacts with the Lewis histo-blood group antigen, Lewis b. The 3D structure for BabA has been determined, and the ligand specifically described. Although BabA is reported to be a glycoprotein, there are limited data examining the effects of glycosylation on the structure and function of this protein. This study examined the folding and thermostability of non-glycosylated recombinant BabA and used computational approaches to predict the effect of glycosylation on the protein, with a focus on its possible heterologous expression in mammalian cells. Three potential O-linked and three potential N-linked glycosylation sites were predicted. Furthermore, the effect of glycan shielding on the solvent-accessible surface area of BabA was examined. Molecular dynamics simulations highlighted local indicators, including root mean square fluctuation and the number of protein-glycan contacts that were affected by glycosylation. Taken together, the findings support a role of glycans in surface shielding and promoting local stabilization in specific areas of the BabA protein. This study helps to strengthen the understanding of the importance of glycosylation and the role it plays in the structure, function, and stability of H. pylori proteins. Full article

Lower respiratory infections are a leading cause of death in children under five years. Human metapneumovirus (HMPV) is an underestimated causal agent of these infections. In this study, the molecular epidemiology of HMPV associated with respiratory infections in Mexican children between August 2023 and August 2024 was determined. Sequences were also analyzed for predicted N- and O-linked glycosylation sites. Overall, 34 sequences from infants with respiratory infections were obtained; 32 were assigned to the A2b2 genotype, one to A2b1, and one to B2. All but one of the A2b2 sequences carried the 111-nucleotide duplication of the G gene; the remaining sequence carried the 180-nucleotide duplication. The samples assigned to the A2b1 and B2 genotypes did not have a duplication. The HMPV-A phylogeny did not show a clustering of Mexican sequences as a single monophyletic group. Four N-linked glycosylation sites were predicted in the HMPV-A sequences and three in the B sequence. The number of O-linked glycosylation sites predicted in HMPV-A ranged from 61 to 77 and were 61 in the HMPV-B sequence. This first description of HMPV genotypes and the diverse array of G protein N- and O-linked glycosylation patterns found in a Mexican pediatric population in the post-pandemic period contributes to the understanding of the global spread of HMPV. Full article

Background: As of 2024, three approved respiratory syncytial virus (RSV) vaccines are licensed for use in adults in the United States: Arexvy™, Abrysvo™, and mRESVIA™. These vaccines are specifically designed to prevent lower respiratory tract disease caused by RSV in adults aged 60 and older. All licensed vaccines rely on stabilized RSV pre-fusion F (pre-F) as the sole antigen. RSV vaccines targeted to the other key RSV surface protein, the G glycoprotein, have been slow to advance because of sequence diversity and a historical association with vaccine-enhanced disease in animal models of infection. The recent development of structure-guided subunit immunogens and immune-modulating adjuvants has renewed interest in RSV G, as the combination of both F and G glycoproteins appears to improve vaccine efficacy over either one individually. RSV G is extensively O-glycosylated, with two mucin-like regions. Methods: This study investigated the effects of manipulation of O-linked glycosylation on a recombinant RSV G vaccine antigen in an RSV/A2 challenge study in BALB/c mice. Conclusions: We found that restricting the O-linked glycosylation on a recombinant RSV G vaccine antigen enhances its immunogenicity and protective efficacy in BALB/c mice. Full article

Ferroptosis, an iron-dependent form of regulated cell death characterized by lipid peroxidation, has emerged as a critical mechanism in cancer biology and therapy. Aberrant glycosylation is a hallmark of cancer, influencing cellular processes from proliferation to immune evasion. Recent evidence has revealed previously underappreciated crosstalk between glycosylation and ferroptosis in cancer cells, where specific glycosylation modifications can determine cellular susceptibility to ferroptotic cell death. This review summarizes the current understanding of how N-linked glycosylation, O-linked glycosylation, and glycosaminoglycan biosynthesis modulate sensitivity to ferroptosis in various cancers. We examine the molecular mechanisms underlying glycosylation-dependent ferroptosis regulation, including the roles of key glycosyltransferases and glycan structures in the oxidative stress response. Furthermore, we discuss the therapeutic potential of targeting the glycosylation–ferroptosis axis for cancer treatment in this emerging field. 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

Fucosylation plays a fundamental role in maintaining cellular functions and biological processes across all animals. As a form of glycosylation, it involves the biochemical addition of fucose, a six-carbon monosaccharide, to biological molecules like lipids, proteins, and glycan chains. This modification is essential for optimizing cellular interactions required for receptor-ligand binding, cell adhesion, immune responses, and development. Disruptions in cellular fucose synthesis or in the mechanisms enabling its transfer to other molecules have been linked to human disease. Inherited defects in the fucosylation pathway are rare, with about thirty patients described. Through genome-wide association studies (GWAS), variants in fucosylation pathway genes have been associated with complex diseases such as glaucoma and stroke, and somatic mutations are often found in cancers. Recent studies have applied targeted genetic animal models to elucidate the mechanisms through which disruptions in fucosylation contribute to disease pathogenesis and progression. Key focus areas include GDP-fucose synthesis through de novo or salvage pathways, GDP-fucose transport into the Golgi and endoplasmic reticulum (ER), and its transfer by fucosyltransferases (FUTs) or protein O-fucosyltransferases (POFUTs) onto acceptor molecules. Loss or gain of function fucosylation gene mutations in animal models such as mice, zebrafish, and invertebrates have provided insights into some fucosylation disease pathogenesis. This review aims to bring together these findings, summarizing key insights from existing animal studies to possibly infer fucosylation disease mechanisms in humans. 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

Photodynamic therapy (PDT) is a minimally invasive technique—used for the local eradication of neoplastic cells—that exploits the interaction of light, oxygen, and a photo-responsive drug called photosensitizer (PS) for the local generation of lethal ROS. Push-pull chromophores, that bear electron donor (D) and acceptor (A) groups linked through a π-electron bridge, are characterized by a non-homogeneous charge distribution in their excited state, with charge transfer from one extremity of the chain to the other one (Internal Charge Transfer—ICT). This phenomenon has a direct impact on the photophysical features of the push-pull compounds, as the bathochromic shift of the emission maxima and intersystem crossing (ISC) of the excited state are directly connected with the production of reactive oxygen species (ROS). In continuing our research regarding the synthesis and use of oligophenylene ethynylenes (OPEs) in PDT, two new push-pull glycosyl OPE-NOF and OPE-ONF—featuring electron-donor N,N-dimethylamino (N) and dimetoxyaryl (O) and acceptor tetrafluoroaryl (F) moieties on the OPE chain—have been efficiently prepared. The interchanged position of the D groups onto the conjugated skeleton was aimed to tune and optimize the push-pull effect, while the introduction of glucoside terminations was directed to give biocompatibility and bioaffinity to the chromophores. OPE-NOF, OPE-ONF, and the synthetic intermediates were fully characterized, and their photophysical properties were investigated by using UV-Vis absorption and emission spectroscopy. OPE-NOF showed a strong charge-transfer character and high PDT effect on HeLa cancer cells when irradiated with non-harmful blue light, causing massive cancer cell death. Full article

Background/Objectives: While various nucleoside and nucleotide analogs have been approved as anticancer and antiviral drugs, their limitations, including low bioavailability and chemotherapeutic resistance, encourage the development of novel structures. In this context, and motivated by our previous findings on bioactive 3′-O-substituted xylofuranosyl nucleosides and 5-guanidine xylofuranose derivatives, we present herein the synthesis and biological evaluation of 5′-guanidino furanosyl nucleosides comprising 6-chloropurine and uracil moieties and a 3-O-benzyl xylofuranosyl unit. Methods: The synthetic methodology was based on the N-glycosylation of a 5-azido 3-O-benzyl xylofuranosyl acetate donor with the silylated nucleobase and a subsequent one-pot sequential two-step protocol involving Staudinger reduction of the thus-obtained 5-azido uracil and N⁷/N⁹-linked purine nucleosides followed by guanidinylation with N,N′-bis(tert-butoxycarbonyl)-N′′-triflylguanidine. The molecules were evaluated for their anticancer and anti-neurodegenerative diseases potential. Results: 5′-Guanidino 6-chloropurine nucleosides revealed dual anticancer and butyrylcholinesterase (BChE)-inhibitory effects. Both N⁹/N⁷-linked nucleosides exhibited mixed-type and selective submicromolar/micromolar BChE inhibiton. The N⁹ regioisomer was the best inhibitor (K_i/K_i′ = 0.89 μM/2.96 μM), while showing low cytotoxicity to FL83B hepatocytes and no cytotoxicity to human neuroblastoma cells (SH-SY5Y). Moreover, the N⁹-linked nucleoside exhibited selective cytotoxicity to prostate cancer cells (DU-145; IC₅₀ = 27.63 μM), while its N⁷ regioisomer was active against all cancer cells tested [DU-145, IC₅₀ = 24.48 μM; colorectal adenocarcinoma (HCT-15, IC₅₀ = 64.07 μM); and breast adenocarcinoma (MCF-7, IC₅₀ = 43.67 μM)]. In turn, the 5′-guanidino uracil nucleoside displayed selective cytotoxicity to HCT-15 cells (IC₅₀ = 76.02 μM) and also showed neuroprotective potential in a Parkinson’s disease SH-SY5Y cells’ damage model. The active molecules exhibited IC₅₀ values close to or lower than those of standard drugs, and comparable, or not significant, neuro- and hepatotoxicity. Conclusions: These findings demonstrate the interest of combining guanidine moieties with nucleoside frameworks towards the search for new therapeutic agents. Full article

O-glycosylation is a common post-translational modification on extracellular and secreted proteins driving biochemical and biophysical interactions at the cell surface. Glycosylation affects drug immunogenicity, efficacy, and clearance, making it a critical attribute of biotherapeutics. Unlike N-linked glycans, O-linked glycans are difficult to characterize because there is no consensus sequence for glycosylation sites on the polypeptide and a universal enzyme to release O-glycans from proteins. To overcome these hurdles, O-glycan analysis and localization require an appropriate and well-validated approach, particularly for recombinant human follicle stimulating hormone-C-terminal peptide (rhFSH-CTP). FSH-CTP consists of a native FSH α/β subunit fused with the C-terminal fragment of a human chorionic gonadotropin (hCG) β subunit, which is heavily O-glycosylated. However, few FSH-CTP O-glycosylation identification methods exist. Thus, we developed a characterization method for the O-linked glycan profile and glycosylation sites of rhFSH-CTP. By means of O-glycan profiling, we identified predominantly core 1-based structures with good reproducibility. For site-specific localization, the O-glycopeptidase OpeRATOR, used with sialidase, helped identify O-glycosylated peptides. Electron transfer/higher-energy collision dissociation (EThcD), combined with OpeRATOR, identified all six glycosylation sites. This approach improves quality control for rhFSH-CTP biosimilars and other CTP-fusion proteins, contributing to the development of standardized O-glycan identification methods. Full article

Sporothrix schenckii is a pathogenic fungus of worldwide distribution and one of the etiological agents of sporotrichosis. The cell wall is the first point of contact with host cells; therefore, its composition has been widely studied. It has a cell wall composed of chitin, β-glucans, and glycoproteins modified with N-linked and O-linked glycans. Protein O-linked glycosylation is mediated by two gene families, PMT and MNT. Therefore, we evaluated the relevance of protein O-linked glycosylation during the interaction of S. schenckii with the host. Independent silencing of the MNT1 and PMT2 was accomplished by interference RNA. Morphological analyses revealed defects in cell morphology in both yeast and mycelial cells; however, these defects differed between MNT1 and PMT2 silencing. Subsequently, the cell wall was characterized, and the silencing of these genes markedly changed cell wall organization. When the silenced strains interacted with human peripheral blood mononuclear cells, a reduced ability to stimulate the proinflammatory cytokines IL-6 and TNFα was found. However, the PMT2-silenced mutants also stimulated higher levels of IL-10 and IL-1β. Interaction with macrophages and neutrophils was also altered, with increased phagocytosis and decreased extracellular trap formation in both sets of silenced strains. Survival assays in Galleria mellonella larvae showed that silencing of any of these genes reduced the ability of S. schenckii to kill the host. In addition, the mutant strains showed defects in the adhesion to extracellular matrix proteins. These data indicate that MNT1 and PMT2 are relevant for cell wall synthesis and interaction with the host. Full article

Alzheimer’s disease (AD) is one of the most common neurodegenerative disorders linked to aging. Major hallmarks of AD pathogenesis include amyloid-β peptide (Aβ) plaques, which are extracellular deposits originating from the processing of the amyloid precursor protein (APP), and neurofibrillary tangles (NFTs), which are intracellular aggregates of tau protein. Recent evidence indicates that disruptions in metal homeostasis and impaired immune recognition of these aggregates trigger neuroinflammation, ultimately driving disease progression. Therefore, a more comprehensive approach is needed to understand the underlying causes of the disease. Patients with AD present abnormal glycan profiles, and most known AD-related molecules are either modified with glycans or involved in glycan regulation. A deeper understanding of how O-glycosylation influences the balance between amyloid-beta peptide production and clearance, as well as microglia’s pro- and anti-inflammatory responses, is crucial for deciphering the early pathogenic events of AD. This review aims to provide a comprehensive summary of the extensive research conducted on the role of mucin-type O-glycosylation in the pathogenesis of AD, discussing its role in disease onset and immune recognition. Full article