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A combined chemo‐enzymatic synthesis/NMR‐based methodology is presented to identify, in unambiguous manner, the distinctive binding epitope within repeating sugar oligomers when binding to protein receptors. The concept is based on the incorporation of 13C‐labels at specific monosaccharide units, selected within a repeating glycan oligomeric structure. No new chemical tags are added, and thus the chemical entity remains the same, while the presence of the 13C‐labeled monosaccharide breaks the NMR chemical shift degeneracy that occurs in the non‐labeled compound and allows the unique identification of the different components of the oligomer. The approach is demonstrated by a proof‐of‐concept study dealing with the interaction of a polylactosamine hexasaccharide with five different galectins that display distinct preferences for these entities. [ABSTRACT FROM AUTHOR]

Background and Aim: Galectin‐1 plays a protective role against colitis by binding with polylactosamine structures on macrophages in β‐1,4‐galactosyltransferase I‐deficient mice, but the precise function of galectin‐1 remains unknown. In the present study, we investigated the anti‐inflammatory role of galectin‐1 on macrophages to ameliorate ulcerative colitis in both animal model and human tissue samples. Methods: The expression of galectin‐1 in colonic tissues of ulcerative colitis patients was evaluated by immunohistochemistry. Cytokine production of mouse bone marrow‐derived macrophages (BMDMs) cultured with galectin‐1 was investigated. Galectin‐1 binding capacity and polylactosamine expression in macrophages stimulated with lipopolysaccharides were evaluated by flow cytometry. BMDMs cultured with galectin‐1 were transferred into Recombination activating gene (Rag) 2−/− mice, and the severity of the dextran sodium sulfate‐induced colitis model was investigated. Furthermore, RNA sequencing was performed to characterize macrophages treated with galectin‐1. Results: In ulcerative colitis patients, tissue expression of galectin‐1was decreased in inflamed mucosa compared with non‐inflamed mucosa. Galectin‐1 induced interleukin‐10 production in BMDMs, and the interleukin‐10 production was abrogated by lactose, which inhibits the interaction of oligosaccharide–galectin binding. Dextran sodium sulfate colitis was significantly ameliorated in Rag2−/− mice undergoing galectin‐1‐treated BMDM transfer compared with those undergoing vehicle‐treated BMDM transfer. RNA sequencing revealed that treatment with galectin‐1 increased the expression of CCAAT/enhancer binding protein β and CD163, but decreased the expression of CD80 on BMDMs. Conclusion: Galectin‐1, whose expression is decreased in the inflamed mucosa of ulcerative colitis patients, can ameliorate murine colitis by conferring oligosaccharide‐dependent anti‐inflammatory properties to macrophages. [ABSTRACT FROM AUTHOR]

Glycosylated [Asn22]lysozyme has been shown to contain N-acctyllactosamine repeats when expressed in chinese hamster ovary (CHO) cells. We find that the major portion of N-acetyllactosamine repeats are associated with diantennary oligosaccharides, In Lec2 CHO cells, which arc deficient in sialylation, glycosylated lysozyme is synthesized with increased contents of N-acetyllactosamine repeats terminating in β-galactosyl residues, In the Lec2 cells and the parental CHO cell line, Pro-5, only a minor portion of the oligosaccharides in lysozyme are of the triantennary type. Previously, it has been shown that the synthesis of N-acetyllactosamine repeats in Asn-linked oligosaccharides is enhanced by an increase in the activity of the elongating β-N-acetylglucosaminyl transferase and by the synthesis of β-1, 6-1inked antennae. The results with glycosylated lysozyme suggest that glycoproteins bearing diantennary oligosaccharides can contain several N-acetyllactosamine repeats and that the number of the latter can be increased by decreasing the activity of the capping sialyl transferases. [ABSTRACT FROM AUTHOR]