A slimy, hydrated mucus gel lines all wet epithelia in the human body, including the eyes, lungs, gastrointestinal and urogenital tracts. Mucus forms the first line of defense while housing trillions of microbes that constitute the microbiota (1). Rarely do these microbes cause infections in healthy mucus (1), suggesting mechanisms exist in the mucus layer that regulate virulence. Using the bacterium Pseudomonas aeruginosa and a 3-dimensional (3D) laboratory model of native mucus, we determined that exposure to mucus triggers the downregulation of virulence genes involved in quorum sensing, siderophore biosynthesis, and toxin secretion, and rapidly disintegrates biofilms, a hallmark of mucosal infections. This phenotypic switch is triggered by mucins, polymers densely grafted with O-linked glycans that form the 3D scaffold inside mucus. Here we show isolated mucins act at various scales, suppressing distinct virulence pathways, promoting a planktonic lifestyle, reducing Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

In many different human disorders, the cellular glycome is altered. An interesting but poorly understood alteration occurs in the mucin-type O-glycome, in which there is aberrant expression of the truncated O-glycans Tn (GalNAcα1-Ser/Thr) and its sialylated version sialyl-Tn (STn) (Neu5Acα2,6GalNAcα1-Ser/Thr). Both Tn and STn are tumor-associated carbohydrate antigens and tumor biomarkers, since they are not expressed normally and appear early in tumorigenesis. Moreover, their expression is strongly associated with poor prognosis and tumor metastasis. The Tn and STn antigens are also expressed in other human diseases and disorders, such as Tn syndrome and IgA nephropathy. The major pathological mechanism for expression of the Tn and STn antigens is compromised T-synthase activity, resulting from alteration of the X-linked gene that encodes for Cosmc, a molecular chaperone specifically required for the correct folding of T-synthase to form active enzyme. This review will summarize our current understanding of the Tn and STn antigens in terms of their biochemistry and role in pathology.

Despite advances in stem cell research, cell transplantation therapy for liver failure is impeded by a shortage of human primary hepatocytes (HPH), along with current differentiation protocol limitations. Several studies have examined the concept of co-culture of human induced pluripotent cells (hiPSCs) with various types of supporting non-parenchymal cells to attain a higher differentiation yield and to improve hepatocyte-like cell functions both in vitro and in vivo . Co-culturing hiPSCs with human endothelial cells (hECs) is a relatively new technique that requires more detailed studies. Using our 3D human embryoid bodies (hEBs) formation technology, we interlaced Human Adipose Microvascular Endothelial Cells (HAMEC) with hiPSCs, leading to a higher differentiation yield and notable improvements across a wide range of hepatic functions. We conducted a comprehensive gene and protein secretion analysis of our HLCs coagulation factors profile, showing promising results in comparison with HPH. Furthermore, a stage-specific glycomic analysis revealed that the differentiated hepatocyte-like clusters (HLCs) resemble the glycan features of a mature tissue rather than cells in culture. We tested our HLCs in animal models, where the presence of HAMEC in the clusters showed a consistently better performance compared to the hiPSCs only group in regard to persistent albumin secretion post-transplantation.

Glycosylation is essential to brain development and function, but prior studies have often been limited to a single analytical technique and excluded region- and sex-specific analyses. Here, using several methodologies, we analyze Asn-linked and Ser/Thr/Tyr-linked protein glycosylation between brain regions and sexes in mice. Brain N-glycans are less complex in sequence and variety compared to other tissues, consisting predominantly of high-mannose and fucosylated/bisected structures. Most brain O-glycans are unbranched, sialylated O-GalNAc and O-mannose structures. A consistent pattern is observed between regions, and sex differences are minimal compared to those in plasma. Brain glycans correlate with RNA expression of their synthetic enzymes, and analysis of glycosylation genes in humans show a global downregulation in the brain compared to other tissues. We hypothesize that this restricted repertoire of protein glycans arises from their tight regulation in the brain. These results provide a roadmap for future studies of glycosylation in neurodevelopment and disease.

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Bronchial mucins from patients suffering from CF (cystic fibrosis) exhibit glycosylation alterations, especially increased amounts of the sialyl-Lewis(x) (NeuAcalpha2-3Galbeta1-4[Fucalpha1-3]GlcNAc-R) and 6-sulfo-sialyl-Lewis(x) (NeuAcalpha2-3Galbeta1-4[Fucalpha1-3][SO(3)H-6]GlcNAc-R) terminal structures. These epitopes are preferential receptors for Pseudomonas aeruginosa, the bacteria responsible for the chronicity of airway infection and involved in the morbidity and early death of CF patients. However, these glycosylation changes cannot be directly linked to defects in CFTR (CF transmembrane conductance regulator) gene expression since cells that secrete airway mucins express no or very low amounts of the protein. Several studies have shown that inflammation may affect glycosylation and sulfation of various glycoproteins, including mucins. In the present study, we show that incubation of macroscopically healthy fragments of human bronchial mucosa with IL-6 (interleukin-6) or IL-8 results in a significant increase in the expression of alpha1,3/4-fucosyltransferases [FUT11 (fucosyltransferase 11 gene) and FUT3], alpha2-6- and alpha2,3-sialyltransferases [ST3GAL6 (alpha2,3-sialyltransferase 6 gene) and ST6GAL2 (alpha2,6-sialyltransferase 2 gene)] and GlcNAc-6-O-sulfotransferases [CHST4 (carbohydrate sulfotransferase 4 gene) and CHST6] mRNA. In parallel, the amounts of sialyl-Lewis(x) and 6-sulfo-sialyl-Lewis(x) epitopes at the periphery of high-molecular-mass proteins, including MUC4, were also increased. In conclusion, our results indicate that IL-6 and -8 may contribute to the increased levels of sialyl-Lewis(x) and 6-sulfo-sialyl-Lewis(x) epitopes on human airway mucins from patients with CF.

The disialoganglioside G(D3) is an oncofetal marker of a variety of human tumors including melanoma and neuroblastoma, playing a key role in tumor progression. G(D3) and 9-O-acetyl-G(D3) are overexpressed in approximately 50% of invasive ductal breast carcinoma, but no relationship has been established between disialoganglioside expression and breast cancer progression. In order to determine the effect of G(D3) expression on breast cancer development, we analyzed the biosynthesis of gangliosides in several breast epithelial cell lines including MDA-MB-231, MCF-7, BT-20, T47-D, and MCF10A, by immunocytochemistry, flow cytometry, and real-time PCR. Our results show that, in comparison to tumors, cultured breast cancer cells express a limited pattern of gangliosides. Disialogangliosides were not detected in any cell line and G(M3) was only observed at the cell surface of MDA-MB-231 cells. To evaluate the influence of G(D3) in breast cancer cell behavior, we established and characterized MDA-MB-231 cells overexpressing G(D3) synthase. We show that G(D3) synthase expressing cells accumulate G(D3), G(D2), and G(T3) at the cell surface. Moreover, G(D3) synthase overexpression bypasses the need of serum for cell growth and increases cell migration. This suggests that G(D3) synthase overexpression may contribute to increasing the malignant properties of breast cancer cells.

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