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Cellular Components of Blood
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Three allelic genes, A1, B1 and O1, and a pair of allelic genes, H and h, determine the formation of the ABO antigens. Gene H is responsible for the enzyme, α-l-fucosyltransferase, which attaches fucose to the GP precursor to form the H antigen. Genes A and B are responsible for α-n-acetyl-d-galactosaminyl transferase and α-d-galactosyltransferase, which attach galactosamine and galactose, respectively, to substance H and thus determine the antigenic specificity of the A and B antigens.
Metabolomics and human breast milkA unique and inimitable food for infants
Published in Moshe Hod, Vincenzo Berghella, Mary E. D'Alton, Gian Carlo Di Renzo, Eduard Gratacós, Vassilios Fanos, New Technologies and Perinatal Medicine, 2019
Flamina Cesare Marincola, Sara Corbu, Roberta Pintus, Angelica Dessì, Vassilios Fanos
Among the applications of metabolomics on HBM, particular attention has been addressed to human milk oligosaccharides (HMOs), the third most abundant component after lactose and fat. HMOs have been shown to play an important role in an infant's development, by influencing the composition of the gut microbiome, modulating the immune system, and helping protect against pathogens (25,26). The utilization of HMOs by the microbiome in the gut has been recently reviewed (27). Every lactating woman has a unique pattern of oligosaccharides. Their presence in HBM is influenced by maternal genetic factors (secretor status and Lewis blood epitopes) and, in particular it depends on the activity of specific fucosyltransferases (28): fucosyltransferase 2 (FUT2) catalyzes the addition of fucose residues via 1–2 linkages on Lewis blood group; fucosyltransferase 3 (FUT3) catalyzes the addition of fucose residues via an 1–3/4 linkage. Depending on the expression of active FUT2 and FUT3 enzymes, women phenotypes can be separated into four groups: (1) Lewis-positive secretors (Se+/Le+) with FUT3 and FUT2 active; (2) Lewis-positive nonsecretor (Se−/Le+) with FUT3 active and FUT2 inactive; (3) i.e., Lewis-negative secretors (Se+/Le−) with FUT3 inactive and FUT2 active; and (4) Lewis-negative nonsecretors (Se−/Le−) with FUT2 and FUT3 inactive.
Host Defense I: Non-specific Immunity
Published in Constantin A. Bona, Francisco A. Bonilla, Textbook of Immunology, 2019
Constantin A. Bona, Francisco A. Bonilla
The last group of adhesion molecules is the selectin family (LEC-CAMs). These molecules resemble lectins and bind to carbohydrate ligands. Most of these are important in lymphocyte homing to various tissues and are also known as addressins. L-selectin(CD62L, also called LAM-1), is expressed on T and B cells, NK cells, neutrophils, and monocyte derivatives. On the lymphocyte surface LAM-1 directs cells to HEV of peripheral lymph nodes. P-selectin (CD62P) is a component of platelet and endothelial cell granules and mediates adhesion to neutrophils and monocytes. The carbohydrate CD 15 (Lewisx) expressed on granulocytes is a ligand for CD62P. IL-1 induces endothelial cells to express E-selectin (CD62E, ELAM-1) which binds to the carbohydrate CD15s (sialyl-Lewisx) on granulocyte membranes. Recently, a small group of patients with recurrent bacterial infections were found to have a deficiency of a fucosyltransferase enzyme which is required to generate the sialyl-Lewis X determinant. This has been called leukocyte adhesion deficiency type 2.
Glycans: potential therapeutic targets for cholangiocarcinoma and their therapeutic and diagnostic implications
Published in Expert Opinion on Therapeutic Targets, 2021
Peripheral glycans, including fucosylated- and sialylated-glycans, were also demonstrated to promote the progression of CCA. Fucosylated-glycans, such as a(1,2)-fucose-modified glycan and Lewis-associated glycans were found to facilitate the migration and invasion of CCA cells [7–9]. Fucosyltransferase (FUT)-1, an enzyme response for a(1,2)-fucose modification, was found to regulate the EGF/EGFR activation in CCA cells [9]. Metastatic abilities of CCA cells were significantly suppressed by specific siRNA against FUT1 and FUT3. Neutralization of surface Lewis-associated antigens using a specific monoclonal antibodies against CA-S27 or sialyl-Lewis A (sLeA) could significantly reduce the metastatic abilities of CCA cells. The metastatic suppression effect was also observed after treatment with Ulex europaeus agglutinin-I (UEA-I, a(1,2)-fucose binding lectin).
Understanding the relationship between norovirus diversity and immunity
Published in Gut Microbes, 2021
Lauren A. Ford-Siltz, Kentaro Tohma, Gabriel I. Parra
HBGAs are carbohydrates expressed on the surface of most epithelial cells and are the determinants of the ABO and Lewis blood group systems.28 Biosynthesis of the different HBGAs is dependent upon multiple glycosyltransferase enzymes, which are responsible for the stepwise addition of monosaccharides onto a precursor carbohydrate molecule. Two of these glycosyltransferases, the fucosyltransferase 1 and 2 (FUT1 and FUT2) enzymes catalyze the addition of a fucose moiety onto the disaccharide precursor via α1,2 linkage, producing the H antigen, which can be further modified.29 Mutations that inactivate the FUT2 gene result in the secretor negative phenotype in humans, which has been shown to provide resistance to infection by certain norovirus genotypes.26,30–33 Recently, stem-cell derived human intestinal enteroids (HIE) have been shown to be susceptible to some human norovirus strains.34 Using HIE, it has been shown that the expression of a functional FUT2 enzyme in the HIE was necessary for attachment and infection of GI.1 and some GII genotypes,27 confirming the relevance of genetic factors to norovirus susceptibility.
Changes in dietary fiber intake in mice reveal associations between colonic mucin O-glycosylation and specific gut bacteria
Published in Gut Microbes, 2020
Hasinika K. A. H. Gamage, Raymond W. W. Chong, Daniel Bucio-Noble, Liisa Kautto, Anandwardhan A. Hardikar, Malcolm S. Ball, Mark P. Molloy, Nicolle H. Packer, Ian T. Paulsen
Fucose, present as the blood group H antigen (Fucα1-2 Galβ1-), was an abundant terminal residue with approximately 60% of O-glycans detected containing at least one Fuc residue (Figure 4). This was consistent with previous studies showing fucosyltransferase 2 (Fut2), an enzyme responsible for attachment of α 1–2 linked Fuc, as the sole fucosyltransferase in mice.13 Mono-fucosylated glycans (F) exhibited the highest abundance in the colonic mucin of mice on HF-NK and HF-BF fiber-supplemented diets. O-glycans terminating with galactose or N-acetylglucosamine (G) and glycans terminating with a single sulfate (GS) were also significantly more abundant in these diets. In contrast, O-glycans containing two Fuc residues (2F), a single Neu5Ac (N), or sulfate and Neu5Ac together (SN), were more abundant in NC and HF compared to both fiber supplemented diets (HF-NK and HF-BF). Previous studies have shown that dietary fiber inclusion can alter the total carbohydrate content of small intestinal mucins in rats.25,26 Our study goes further and provides detailed information on mucin glycosylation changes at the O-linked glycan structural level in response to diet.