Glycoconjugate Journal最新文献

Reduction of glucose transporter 1 (GLUT1), even deletion, may results in cartilage fibrosis and osteoarthritis. This study aims to investigate the SUMOylation of GLUT1 in osteoarthritis through small ubiquitin-like modifier 1(SUMO1), and explore the role of SUMOylated GLUT1 in glycometabolism, proliferation and apoptosis in chondrocytes. Human chondrocytes were incubated with 10 ng/mL of IL-1β to mimic osteoarthritis in vitro. GLUT1, SUMO1 and Chondrocyte-related genes including COL2A1, MMP13 and ADAMTS4 were evaluated using western blot. Cell viability and cell apoptosis of chondrocytes were measured by cell counting kit-8 assay and flow cytometry, respectively. The changes in glycometabolism were evaluated using extracellular acidification rate (ECAR) and glucose uptake assay. Co-immunoprecipitation (Co-IP) was used to verify the interaction between GLUT1 and SUMO1. The stabilization role of SUMO1 in GLUT1 was determined by cycloheximide assay. IL-1β induced the decrease of GLUT1, cell viability, ECAR, glucose uptake and COL2A1 and the increase of cell apoptosis, MMP13 and ADAMTS4 in chondrocytes. However, overexpression of SUMO1 led to the reduction of cell apoptosis, MMP13 and ADAMTS4 and the elevation of GLUT1, cell viability, ECAR, glucose uptake and COL2A1 in IL-1β-stimulated chondrocytes. There was SUMOylation sites on GLUT1. Intriguingly, SUMO1 was significantly enriched in GLUT1 using Co-IP assay, and stabilized GLUT1 in chondrocytes. SUMO1-mediated SUMOylation is capable of stabilizing GLUT1 to inhibit glycometabilsm disorder and cell apoptosis in IL-1β-stimulated chondrocytes.

Glycosaminoglycans (GAGs) are essential bone extracellular matrix molecules that regulate osteoblast differentiation. Numerous studies have explored endogenous and exogenous GAG osteoanabolic activities using appropriate in vitro and in vivo models. However, GAGs' underlying the mechanism of action and structure-function relationships need to be elucidated in detail. Earlier, we showed that exogenous GAG can bring about osteogenesis in pre-osteoblast cells. In the present study, we have elucidated the mechanism of action of exogenous GAGs, especially of the chondroitin sulfate/dermatan sulfate (CS/DS) class on osteogenesis. GAGs were immobilized, and osteoblast differentiation was evaluated in MC3T3-E1 cells. Results indicated that GAGs supported osteoblast differentiation by promoting collagen production, extracellular matrix formation, and subsequent mineralization. We elucidated the mechanisms underlying these effects by assessing the key signaling molecules involved in osteogenesis in response to exogenous CS/DS with/without BMP2. CS/DS alone significantly increased pERK1/2 and ATF4 expression levels differentially in a time-dependent manner without significant effects on BMP2, RUNX2, and pSMAD5 protein expression. On the other hand, CS/DS, in the presence of BMP2, differentially increased BMP2, pSMAD5, pERK1/2, RUNX2, and ATF4 expression levels at various time points. Collectively, these results strongly suggest that CS/DS can promote osteogenesis, and in the presence of BMP2, it could promote SMAD-mediated ERK-dependent osteogenesis.

In this study, spatial and single-cell transcriptome techniques were used to investigate the role of beta-galactoside alpha-2,6-sialyltransferase 1 (ST6GAL1) in promoting peritoneal metastasis in ovarian cancer epithelial cells. We collected single-cell transcriptomic (GSE130000) and spatial transcriptomic datasets (GSE211956) from the Gene Expression Omnibus and RNA-sequencing data from The Cancer Genome Atlas. The Robust Cell Type Decomposition (RCTD) approach was implemented to integrate spatial and single-cell transcriptomic data. In addition, pseudo-time trajectory analysis, cell-cell communication networks, transcription factor activity profiling, spatial interaction mapping, and prognostic significance of gene expression were assessed. A significant enrichment of ST6GAL1 was observed in the epithelial cells of ovarian cancer, particularly in peritoneal metastases, which exhibited elevated metabolic activity compared to primary tumors. The levels of ST6GAL1 were significantly high in peritumoral and adjacent non-tumorous tissues, with increased metabolic activity, while the tumor core demonstrated ST6GAL1-negative epithelial cells. Extensive cell-cell communication and transcription factor networks were unraveled, potentially influencing vascular permeability and intracellular signaling. Clinically, high expression of ST6GAL1 in epithelial cells is associated with diminished progression-free survival, indicating its prognostic potential. In conclusion, ST6GAL1 is likely to significantly impact the progression and metastasis of ovarian cancer.

Dengue viruses (DENV) are transmitted to humans through mosquito bites and infect millions globally. DENV uses heparan sulfate (HS) for attachment and cell entry by binding the envelope protein to highly sulfated HS on target cells. Therefore, inhibiting the binding between DENV and HS could be a promising strategy for preventing DENV infection. In the current study, the interactions between DENV envelope protein (from Type 2 DENV) and heparin (a surrogate for HS) were analyzed using competition solution SPR. Results demonstrate that heparin binds to DENV envelope protein with high affinity (K_D = 8.83 nM). Competitive Solution SPR assays using surface-immobilized heparin and a series of naturally-sourced and semi-synthetic sulfated glycans demonstrated significant inhibitory activity against the binding of DENV envelope proteins to heparin. This study of molecular interactions could provide insights into the development of therapeutics for DENV infection.

Lysosomal storage diseases (LSDs) are genetic disorders caused by mutations in lysosomal enzymes, lysosomal membrane proteins or genes related to intracellular transport that result in impaired lysosomal function. Currently, the primary treatment for several LSDs is enzyme replacement therapy (ERT), which involves intravenous administration of the deficient lysosomal enzymes to ameliorate symptoms. The efficacy of ERT largely depends on the mannose-6-phosphate (M6P) modification of the N-glycans associated with the enzyme, as M6P is a marker for the recognition and trafficking of lysosomal enzymes. In cells, N-glycan processing and M6P modification occur in the endoplasmic reticulum and Golgi apparatus. This is a complex process involving multiple enzymes. In the trans-Golgi network (TGN), M6P-modified enzymes are recognized by the cation-independent mannose-6-phosphate receptor (CIMPR) and transported to the lysosome to exert their activities. In this study, we used the 9th domain of CIMPR, which exhibits a high affinity for M6P binding, and fused it with the Fc domain of human immunoglobulin G₁ (IgG₁). The resulting fusion protein specifically binds to M6P-modified proteins. This provides a tool for the rapid detection and concentration of M6P-containing recombinant enzymes to assess the effectiveness of ERT. The advantages of this approach include its high specificity and sensitivity and may lead to the development of new treatments for LSDs.

Glycoconjugates, including glycans on proteins and lipids, have obtained significant attention due to their critical roles in both intracellular and intercellular biological functions and processes. Notably, recent discoveries have revealed the presence of glycosylated RNAs (glycoRNAs) on cell surfaces. Despite the well-characterized roles of RNA modifications, RNA glycosylation remains relatively unexplored. In this study, we investigate the relationship between N-glycosylation and RNA glycosylation. Using a recombinant Siglec11-Fc as a probe, we detected surface sialylated glycoRNAs in human cell lines and identified their dependency on the catalytic isoforms of the oligosaccharyltransferase (OST) complex, implicating STT3A-dependent protein glycosylation as a predominant contributor for affecting indirect generation of glycoRNAs. Additionally, perturbations in N-glycan biosynthesis pathways or changes in N-glycan structure impact surface sialylated glycoRNA levels, indicating a regulatory role of glycan metabolic pathways in RNA glycosylation. Together, our results underscore the intricate relationship between protein N-glycosylation and processing and RNA biology.

Stage-specific embryonic antigen-4 (SSEA-4) is a developmentally regulated antigen, while expression level of SSEA-4 and / or its synthase ST3GAL2 is associated with prognosis in various malignancies. We have reported a prominent increase of SSEA-4 in castration-resistant prostate cancer (CRPC) and its negative correlation with the androgen receptor (AR). Meanwhile, loss of AR has increased to approximately 30% with the growing use of androgen receptor signaling inhibitor for metastatic CRPC (mCRPC). However, monitoring the progression status of AR-negative prostate cancer is a challenge because it does not produce prostate-specific antigen. Based on the negative relationship of expression between AR and SSEA-4, we hypothesized that a soluble molecule synchronized with SSEA-4 in expression could be a serum marker candidate for AR-negative prostate cancer. Thus, we investigated the molecular background of SSEA-4 expression by ST3GAL2-knockout in DU145 cells. Here we show that MUC1 is identified as a molecule associated with ST3GAL2 and expressed in AR-negative prostate cancer. A negative correlation of expression between AR and MUC1 was observed in prostate cancer cell lines and CRPC tissues. The average rate of MUC1 expression was nearly 60% in AR-negative prostate cancer cells in CRPC tissues. Level of serum CA15-3 (MUC1) was the highest in mCRPC among various stages and its higher level was associated with faster progression of mCRPC. Our results demonstrate that MUC1 is identified as a ST3GAL2-associated molecule and expressed in AR-negative CRPC cells. Furthermore, level of serum CA15-3 may reflect the progression status of mCRPC.

Obesity is an epidemic associated with platelet and vascular disorders. Platelet O-GlcNAcylation has been poorly studied in obese subjects. We aimed to evaluate O-linked N-acetyl-glucosamine (O-GlcNAc) levels and platelet activity in obese insulin-resistant (ObIR) subjects. Six healthy and six insulin-resistant obese subjects with a body mass index of 22.6 kg/m² (SD ± 2.2) and 35.6 kg/m² (SD ± 3.8), respectively, were included. Flow cytometry was used to measure markers of platelet activity, expression of P-selectin (CD62P antibody), glycoprotein IIb/IIIa (integrins αIIbβ3 binding to PAC-1 antibody), and thrombin stimulation. O-GlcNAc was determined in the platelets of all test subjects by cytofluometry, intracellular calcium, percentage of platelet aggregation, and immunofluorescence microscopy and Western blot were used to assess O-GlcNAc and OGT (O-GlcNAc transferase) in platelets. Platelets from ObIR subjects had on average 221.4 nM intracellular calcium, 81.89% PAC-1, 22.85% CD62P, 57.48% OGT, and 66.62% O-GlcNAc, while platelets from healthy subjects had on average 719.2 nM intracellular calcium, 4.99% PAC-1, 3.17% CD62P, 18.38% OGT, and 23.41% O-GlcNAc. ObIR subjects showed lower platelet aggregation than healthy subjects, 13.83% and 54%, respectively. The results show that ObIR subjects have increased O-GlcNAc, and increased intraplatelet calcium associated with platelet hyperactivity and compared to healthy subjects, suggesting that changes in platelet protein O-GlcNAcylation and platelet activity might serve as a possible prognostic tool for insulin resistance, prediabetes and its progression to type 2 diabetes mellitus.

This comprehensive review meticulously compiles data on an array of lectins and their interactions with different cancer types through specific glycans. Crucially, it establishes the link between aberrant glycosylation and cancer types. This repository of lectin-defined glycan signatures, assumes paramount importance in the realm of cancer and its dynamic nature. Cancer, known for its remarkable heterogeneity and individualized behaviour, can be better understood through these glycan signatures. The current review discusses the important lectins and their carbohydrate specificities, especially recognizing glycans of cancer origin. The review also addresses the key aspects of differentially expressed glycans on normal and cancerous cell surfaces. Specific cancer types highlighted in this review include breast cancer, colon cancer, glioblastoma, cervical cancer, lung cancer, liver cancer, and leukaemia. The glycan profiles unveiled through this review hold the key to tailor-made treatment and precise diagnostics. It opens up avenues to explore the potential of targeting glycosyltransferases and glycosidases linked with cancer advancement and metastasis. Armed with knowledge about specific glycan expressions, researchers can design targeted therapies to modulate glycan profiles, potentially hampering the advance of this relentless disease.