Glycobiology最新文献

Objective: This study aimed to identify distinct IgA1 N-glycan composition in patients with ankylosing spondylitis (AS) compared with healthy controls and to explore their associations with inflammatory markers and disease activity indices.

Methods: Serum samples were collected from 36 patients with AS and 35 healthy controls. The diagnosis of AS was based on the New York criteria. Clinical assessments included inflammatory markers (ESR, CRP, and IgA) and disease activity indices (BASDAI, ASDAS-ESR, and ASDAS-CRP). IgA1 was isolated using affinity purification and gel filtration chromatography, followed by mass spectrometry to identify N-glycans.

Results: Among the 23 detected N-glycan patterns, significant differences were observed in 13 of the 18 N-glycans at the N144 site and in all five N-glycans at the N340 site between patients with AS and controls. Notably, the glycans HexNAc3Hex4NeuAc1, HexNAc4Hex4NeuAc1 and HexNAc5Hex5NeuAc1 at N144 demonstrated strong associations with all three inflammatory markers, including ESR, CRP, and IgA (P < 0.001). Levels of HexNAc4Hex4NeuAc1 were significantly elevated in patients with AS compared with those in the healthy controls. Increased sialylation and galactosylation, along with decreased fucosylation, were noted at N144 of IgA1 in patients with AS. Conversely, no glycans at N340 showed a correlation with all inflammatory markers simultaneously or with any disease activity indicators.

Conclusion: IgA1 from patients with AS exhibited distinct glycosylation traits compared with controls, with elevated levels of HexNAc₄Hex₄NeuAc₁ at N144 associated with inflammatory markers. These findings suggested that differential glycosylation patterns of IgA1 may play a role in the pathogenesis of AS.

Mucin type O-glycan core elongation is typically performed by the C1GALT1, B3GNT6, and ST6GalNAc-I/-II O-glycosyltransferases. These enzymes target the Tn antigen (GalNAc-O-Thr/Ser) dictating the fate of O-glycan elongation, playing important roles in health and disease. Changes in transferase expression and glycan structure are commonly associated with diseases such as cancer, Tn-syndrome, and ulcerative colitis. Despite their significance, their substrate specificities and their biological roles remain elusive. Here, we examine the roles of flanking glycopeptide substrate charge using a library of differently charged glycopeptides and a small library of PSGL-1 Thr57 based charged glycopeptides. We found that C1GALT1 was most influenced by flanking charge preferring negatively charged substrates, while B3GNT6 and ST6GalNAc-II were less influenced, showing unique N- and C-terminal charge preferences. Interestingly, ST6GalNAc-I was not influenced by flanking charge. These charge specificities were further maintained against the charged PSGL-1 glycopeptides, although ST6GalNAc-I showed an increased preference towards a remote N-terminal positive charge. The observed charge preferences were to a large part driven by substrate interactions with the electrostatic surface of the transferase. We propose that negative flanking charge may assist C1GALT1 in targeting key glycosites such as in PSGL-1 and podoplanin. Our findings are consistent with a Golgi hierarchy, where the cis-Golgi localized GalNAc-Ts and C1GALT1 determine the site and thus fate of glycosylation, while the trans-Golgi less-specific ST6GalNAc-I provides a final capping function. This characterization of substrate charge preference furthers our understanding of how these enzymes select their substrates and may contribute to our understanding of their biological roles.

Accumulating evidences have shown that unfolded protein response (UPR) contributes to the increased survival of tumor cells under endoplasmic reticulum (ER) stress conditions. Malectin is an ER-resident lectin that selectively traps misfolded glycoproteins in ER for degradation, and its expression is upregulated upon ER stress. However, contribution of malectin to malignant behavior of tumor has not been reported. Here, we revealed that malectin expression is aberrantly up-regulated in human hepatocellular carcinoma (HCC) tissues and HCC cell lines compared to their matched normal tissues and cell lines. Knockout of malectin in two HCC cell lines HepG2 and QGY-7703 using CRISPR-Cas9 technology had no obvious effects on cell proliferation, but significantly suppressed cell colony formation, migration and invasion. Consistently, subcutaneously implanted malectin-deficient HCC cells in nude mice also showed an obvious decrease in tumor growth. These results indicate that malectin might play an oncogenic role in HCC tumorigenesis and development.

Corticosteroid-binding globulin (CBG) is a serum glycoprotein that binds and delivers anti-inflammatory cortisol to inflammatory sites through neutrophil elastase-mediated proteolysis of an exposed reactive centre loop (RCL) on CBG. Timely and tissue-specific delivery of cortisol is critical to alleviate inflammation including in life-threatening septic shock conditions. Herein, we firstly summarise our recently published report of functional RCL O- and N-glycosylation events of serum CBG (Chernykh, J Biol Chem, 2023). A key finding of that published work was the LC-MS/MS-based discovery of RCL O-glycans at Thr342 and Thr345 of serum CBG and their inhibitory roles in neutrophil elastase-mediated RCL proteolysis. While these observations are of significance as they implicate RCL O-glycosylation as a potential regulator of cortisol delivery, the link to septic shock remains unexplored. To this end, we used a similar LC-MS/MS approach to profile the RCL O-glycosylation of CBG purified from serum of twelve septic shock patients. Serum CBG from all patients exhibited RCL O-glycosylation comprising (di)sialyl T (NeuAc1-2Gal1GalNAc1) core 1-type O-glycan structures decorating exclusively the Thr342 site. Importantly, relative to less severe cases, individuals presenting with the most severe illness displayed elevated RCL O-glycosylation upon ICU admission, suggesting a previously unknown link to septic shock severity. Overall, we have elucidated the coordinated RCL N- and O-glycosylation events of serum CBG, which improve our understanding of molecular mechanisms governing the timely and tissue-specific delivery of cortisol to inflammatory sites. This work provides clues to molecular aberrations and disease mechanisms underpinning septic shock.

The MIRAGE (Minimum Information Required for a Glycomics Experiment) project has been established by experts in glycobiology, glycoanalytics, and glycoinformatics under the auspieces of the Beilstein-Institut. The working group aims to develop guidelines for reporting results from various experiments and analyses conducted in structural and functional studies of glycans in the scientific literature. Previous guidelines have been established for glycomic analytics, including mass spectrometry and glycan microarrays. Lectin microarrays are used worldwide for glycan profiling of various biological samples, but there are often insufficient reports on information about experimental methods such as sample preparation and fluorescence labeling. Here, we propose guidelines specifically designed to improve the standards for reporting data from lectin microarray analyses. For each of the seven areas in the workflow of a lectin microarray experiment, we provide recommendations for the minimum information that should be included when reporting results. When adopted by the scientific community the MIRAGE lectin microarray guidelines are expected to enhance data interpretation, facilitate comparison of data between laboratories and encourage the deposition of lectin microarray data in international databases.

Approximately 300,000 American men were diagnosed with prostate cancer in 2024. Existing screening approaches based on measuring levels of prostate-specific antigen in the blood lack specificity for prostate cancer. Studying the glycans attached to proteins has the potential to generate new biomarker candidates and/or increase the specificity of existing protein biomarkers, and studying protein glycosylation changes in prostate cancer could also add new information to our understanding of prostate cancer biology. Here, we present the analysis of N-glycoproteins in clinical prostate cancer tissue and patient-matched, non-cancerous adjacent tissue using LC-MS/MS-based intact N-linked glycopeptide analysis. This analysis allowed us to characterize protein N-linked glycosylation changes in prostate cancer at the glycoprotein, glycopeptide, and glycosite levels. Overall, 1894 unique N-glycosites on 7022 unique N-glycopeptides from 1354 unique glycoproteins were identified. Importantly, we observed an overall increase in glycoprotein, glycopeptide, and glycosite counts in prostate cancer tissue than non-cancerous tissue. We identified biological functions enriched in prostate cancer that relate to cancer development. Additionally, we characterized N-glycosite-specific changes in prostate cancer, demonstrating significant meta- and micro-heterogeneity in N-glycan composition in prostate cancer in comparison to non-cancerous tissue. Our findings support the idea that protein glycosylation is heavily impacted and aberrant in prostate cancer and provide examples of N-glycosite-specific changes that could be exploited for more specific markers of prostate cancer.