Glycoconjugate Journal最新文献

Diabetes mellitus (DM) is marked by prolonged elevated blood glucose levels, which lead to the formation of covalent adducts between glucose and plasma proteins through a non-enzymatic reaction called glycation. This biochemical process plays a crucial role in the development of DM complications, including retinopathy, nephropathy, neuropathy, and cardiomyopathy, while also impacting conditions such as rheumatoid arthritis, osteoporosis, and aging. Glycation alters the molecular structure, enzymatic activity, and receptor interactions of proteins, affecting their normal functions. Advanced glycation end products (AGEs) arise from these modifications, forming cross-links within and between cells, which affect proteins and other vital biomolecules, such as lipids and nucleic acids. This contributes significantly to the complex complications associated with DM. Recent studies highlight the interaction between AGEs and their specific receptors, receptor for advanced glycation end products (RAGE), located on the plasma membrane. This involvement initiates changes in intracellular signaling, alters gene expression, and stimulates the release of pro-inflammatory cytokines and reactive oxygen species. This review examines the glycation of key plasma proteins albumin, fibrinogen, globulins, and collagen and discusses the various AGEs formed. Furthermore, it elucidates the role of AGEs in the exacerbation of DM complications, providing a comprehensive overview of the molecular pathways involved and the systemic impact of these glycation products.

Norovirus (NoV), an important cause of human viral gastroenteritis worldwide, recognizes human histo-blood group antigens (HBGAs) as receptors. Oysters are a vector of foodborne transmission of NoV, and HBGAs have been found in oyster tissues. In this study, CgFUT1 and CgFUT2, the key genes involved in the synthesis of HBGAs in Crassostrea gigas, were successfully expressed in Pichia pastoris, and 32.6 kDa target proteins were obtained after purification, concentration, and dialysis treatments. Western blot analysis using FUT1 and FUT2 antibodies showed that CgFUT1 and CgFUT2 have antigenic similarity as human FUT1 and FUT2. Enzyme catalysis assays using Galβ1-3GlcNAc and Galβ1-4GlcNAc as substrates showed that these substrates react with GDP-Fuc to generate Fucα1-2GalβGlcNAc under the action of CgFUT1 and CgFUT2. High-resolution mass spectrometry analysis revealed that CgFUT1 and CgFUT2 have the same substrate specificity, both reacting with Galβ1-3GlcNAc and Galβ1-4GlcNAc. The results of this study demonstrate the probable role of CgFUT1 and CgFUT2 in regulating substrates for H antigen synthesis in oysters and provide a reference for future studies into the functions of these genes. The study also lays a foundation for further exploration of the molecular mechanisms underlying NoV accumulation in oysters.

Glycosylation plays a critical role in various biological processes and is essential for cell survival. Aberrant glycosylation has been implicated in numerous diseases, including cancer. Lung cancer remains the leading cause of cancer-related mortality worldwide. The correlation between lung cancer progression and abnormal glycosylation has been demonstrated previously. Asparagine-linked glycosylation protein 1 (ALG1) is a key enzyme involved in the N-linked glycosylation process; however, its role in cancer progression remains unclear. In this study, we investigated the function of ALG1 in lung cancer progression. Analysis of the Cancer Genome Atlas (TCGA) dataset revealed that ALG1 expression was significantly upregulated in lung tumor tissues and was associated with poor patient prognosis. To explore its functional relevance, ALG1 expression was depleted in A549 lung adenocarcinoma cells using CRISPR-Cas9-mediated knockout. Loss of ALG1 led to reduced levels of protein N-linked glycosylation and induced an endoplasmic reticulum (ER)-stress response. Functionally, ALG1 knockout significantly impaired A549 cell proliferation, migration, and invasion, as evidenced by phenotypic assays and molecular markers. Moreover, the extent of glycosylation deficiency was positively correlated with ER-stress activation and inversely associated with cancer cell aggressiveness. These findings suggest that ALG1 promotes lung cancer aggressiveness through the regulation of protein glycosylation and modulation of ER-stress pathways. Overall, this study highlights the potential of ALG1 as a therapeutic target and a prognostic biomarker for lung adenocarcinoma patients.

The advanced glycation end-product N^δ-(5-hydro-4-imidazolon-2-yl)ornithine (G-H1) accumulates during the progress of atherosclerosis with type 2 diabetes. Therefore, G-H1 might serve as early diagnostic marker of atherosclerosis, and its inhibition could become a strategy to prevent the pathogenesis of this disease. This study therefore aimed to determine the feasibility of an anti-G-H1 monoclonal antibody-based screen for G-H1 inhibitors. Mice were immunized with G-H1-keyhole limpet hemocyanin prepared with synthesized G-H1 standards to produce an anti-G-H1 monoclonal antibody (1E9). The specificity of 1E9 and levels of G-H1 were determined using an enzyme-linked immunosorbent assay (ELISA). The G-H1 levels correlated with those measured using liquid chromatography (LC)-tandem mass spectrometry (MS). We then mixed arginine with various glyoxal (GO) concentrations and applied GO-modified collagen and albumin to determine the conditions required for G-H1 formation. To screen for G-H1 inhibitors, an ELISA-based protocol was developed and leveraged with aminoguanidine to determine the inhibitory effect of screening compounds on G-H1 formation. The specificity of 1E9 for G-H1 was high. The abundance of G-H1 formation in glyoxal-modified arginine was maximal with 2 mM GO, which aligned with the LC-MS/MS and ELISA results. However, G-H1 was below the detection limit for the GO-modified proteins. Aminoguanidine inhibited G-H1 formation in ribose-modified arginine in a concentration-dependent manner. Overall, our findings emphasize the potential of 1E9 to specifically detect free G-H1 and its value for screening G-H1 inhibitors.

Cancer remains one of the leading causes of death worldwide. Due to the multiple molecular mechanisms involved in cell transformation, its biology continues to be studied from different perspectives and in other research areas. A hallmark of cancer is its accelerated proliferation and overactivation of the cell cycle, caused by a dysregulated metabolism and the activation of different signaling pathways, such as the PI3/K-Akt pathway. On the other hand, the hexosamine biosynthetic pathway plays an essential role in producing UDP-GlcNAc, the primary substrate for O-GlcNAcylation. This non-canonical post-translational modification regulates protein stability, localization and interactions. This work aims to examine the role of the O-GlcNAcylation in regulating the cell cycle across diverse types of cancer and its involvement in the PI3/K-Akt pathway as a promoter of the cell cycle progression. Additionally, the study also proposes new alternatives for cancer diagnosis, prognosis, and treatment.

Concern over COVID-19 has arisen from continuous mutations in SARS-CoV-2 genome leading to emergence of novel variants. A detailed study and understanding of N-linked glycans (NAGs) of SARS-CoV-2 spike protein are key for the development of vaccines and new therapeutic strategies. Potential of four Cucurbitaceae seed lectins (CSLs) to inhibit SARS-CoV-2 attachment to host cells via interaction with receptor binding domain (RBD), was determined by Molecular Docking using PRODIGY and LZerD web servers. Among them, Luffa cylindrica lectin (PDB ID: 1NIO) displayed the most significant binding (B.E.: -24.9 kcal/mol; K_d: 0.052 aM). Further, docking (HADDOCK version 2.4) and interaction analysis (PDBsum and LigPlot+) of 1NIO with defined glycan site of SARS-CoV-2 spike protein revealed that glycans NAGs 1303, 1304, 1305, 1309 and 1314 on spike protein formed stable interactions with NAGs 248 and 249 on the lectin. Notably, NAG248 played a dual role in glycan-glycan interaction and binding. Momordia charantia seed lectin (MCSL) was partially purified using a combination of ethanol precipitation and affinity chromatography. Hemagglutination test confirmed antiviral activity and validated the utility of MCSL on human samples. Toxicity assessment of MCSL on normal HEK-293 cells using MTT assay revealed no significant effect on their morphology and viability at 10-100 µg/mL. Thus, CSLs have the potential to emerge as promising broad spectrum antiviral candidates against COVID-19 if investigated further. The present work is unique in that no such work is being done presently on anti-SARS-CoV-2 potential of CSLs. Also, very few in silico studies focusing on lectin-glycan interactions exist to date.

The study aimed to verify whether the expression of glycosaminoglycans (GAGs) and proteoglycans (PGs) in the tumor matrix affects the plasticity of mesothelioma and its relationship with the phenotype, progression, and resistance to treatment of malignant mesothelioma (MM). As MM is highly aggressive, understanding the molecular mechanisms that regulate the abilities of tumor cells to alter their behaviors and shapes is essential to the development of new therapeutic strategies. To test this hypothesis, we studied 66 samples of human biphasic MM. The expression levels of the GAGs heparan sulfate (HS) and chondroitin sulfate (SC), as well as the PGs versican, biglycan, and perlecan were detected using immunohistochemistry, and their expression was quantified using semi-automated digital analysis. We found that the fusiform phenotype of MM cells was associated with higher expression levels of HS, versican, and biglycan (all P-values < 0.001) in the extracellular matrix. This suggests that the increase and eventual rapid turnover of cell membrane PGs resulted in a variation in shape from polygonal to fusiform phenotypes, whereas GAGs were associated with cell aggregation-thus indicating the distinct functions of different GAGs. Multivariate Cox regression analysis showed that non-surgical patients (hazard ratio [HR]: 4.03 (1.26-12.82); P = 0.02), whose tumors presented necrosis (P < 0.001), high HS expression (P = 0.02), and low biglycan expression (HR: 2.68 [1.16-6.18]; P = 0.02) had significantly worse overall survival rates. We concluded that the expression of GAGs and PGs in the ECM affects the plasticity of MM, modifies its phenotype, and facilitates both its progression and resistance to treatment.

Gram-positive bacterial biomembranes are composed of phosphatidyl glycerol (PG), cardiolipin (CL), and dihexaosyl diglycerides (DH-DG) as the major lipid constituents. The carbohydrate structures of DH-DG are specific to the particular bacterial species and we previously revealed them to have immunologically active properties. To characterize the species-structure relationship of glycolipids in Gram-positive bacteria, the structures of DH-DG in Pediococcus pentosaceus (PP) for producing fermented soybean paste (miso) and Tetragenococcus halophilus (TH) for soy sauce were determined in comparison with those in Lactobacillus, Streptococcus and Staphylococcus species. They were shown to be Glcα1-2Glcα1-3'DG (kojibiosyl DG) with 18:1(oleic acid) and 18:1 as the fatty acids for PP, and that with 16:0 (palmitic acid) and 18:1 for TH, and their carbohydrate structures were identical to that in Streptococcus salivarius, a symbiotic bacterium in the human oral cavity. Additionally, both bacteria contained an acidic glycolipid, in which glycerol phosphate was attached to the 6-position of the nonreducing terminal Glc residue of DH-DG. TLC immunostaining with human sera revealed antibodies to Galα1-2Glcα1-3'DG (LacDH-DG) from Lactobacillus species and Glcβ1-6Glcβ1-3'DG (StaDH-DG) from Staphylococcus species, but not to Glcα1-2Glcα1-3'DG (StrDH-DG) from Streptococcus species, in 2 out of 20 human sera. Given that one serum sample with anti-StaDH-DG antibodies was from a patient who had suffered from food poisoning due to Staphylococcus aureus 6 months previously, the antibodies to bacterial DH-DG were thought to have arisen via bacterial infection.

Mutations in the glucocerebrosidase GBA gene, encoding the lysosomal enzyme β-glucocerebrosidase, represent the most frequent genetic risk factor for Parkinson's disease, leading to lysosomal dysfunction, α-synuclein aggregation, and mitochondrial impairment. In this study, we investigated the therapeutic potential of GM1 ganglioside and its oligosaccharide portion (OligoGM1) in a cellular model of GBA-associated Parkinson's disease, using SH-SY5Y neuroblastoma cells carrying the L444P GBA mutation. We observed that both GM1 and OligoGM1 reduced α-synuclein accumulation and improved cell viability. Notably, only OligoGM1 attenuated lysosomal overload and restored mitophagy. Additionally, OligoGM1 significantly prevented 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced toxicity, including lysosomal dysfunction, reactive oxidative species-overproduction, and mitochondrial energy failure, whereas GM1 failed to provide protection. These findings highlight the selective and multifaceted neuroprotective actions of OligoGM1 under both genetic conditions and environmental stress. Due to its small, hydrophilic nature and capacity to cross the blood-brain barrier, OligoGM1 emerges as a promising therapeutic candidate for GBA-related and potentially idiopathic forms of Parkinson's Disease.