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Galactosialidosis
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
That the primary defect was not in sialidase was shown by complementation of the cells of patients with sialidosis by hybridization with cells of patients with the combined defect [11, 13]. Further, in the combined defect cells, both enzyme defects could be restored by a glycoprotein corrective factor produced in culture by normal fibroblasts or those of β-galactosidase deficiency indicating the presence of a third protein acting as a corrective factor. The turnover of β-galactosidase in normal fibroblasts was 10 days, while in the cells deficient in both enzymes it was less than one day [14] and, in experiments with purified enzyme, it was clear that the rapid turnover was caused by proteolytic degradation of the enzyme [15, 16]. The disorder was named galactosialidosis in 1981 [17]. The molecular defect was found by d'Azzo and colleagues [16] to be in the PPCA, which aggregates with both enzymes to form multimers that resist lysosomal degradation. The gene has been mapped to chromosome 20q13.1 [18, 19], and the human cDNA has been cloned [20]. Mutations have been discovered [21, 22]. The number of patients reported has been small, the majority in the juvenile or adult variants.
Lectin
Published in Masahiko Mori, Histochemistry of the Salivary Glands, 2019
Lectin binding features of ductal segments were more complicated compared to acinar cells. SBA and UEA-1 bindings in ducts showed increased staining after amylase digestion (Figure 6 b). Bindings for PNA, UEA-1, and WGA in ductal cells were also intensely enhanced following sialidase pretreatments (Figure 5 e, f), suggesting sialic acid may be degradated, and newly exposed terminal sugar residues in complex carbohydrates may bind to lectin. WGA staining after sialidase digestion suggested substantial amounts in intercalated duct cells (Figure 5 e). In trypsin digested sections, stains for Con A, RCA-1, SBA, UEA-1, and WGA were usually increased in ductal cells, and UEA-1 binding was particularly enhanced (Figure 4 a, d, 5 c, 6 c). However, DBA and PNA lectin bindings were not changed. Born et al.31 noted that basal cells of ductal segments stained for PNA, and intercalated duct cells were also strongly stained for PNL and Con A lectins.
Rotavirus
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Lijuan Yuan, Tammy Bui, Ashwin Ramesh
HBGAs are not the only glycans that have been demonstrated to interact with rotavirus. VP8* also interacts with gangliosides in a strain-dependent manner.117 As stated previously, some animal strains do bind sialic acid as confirmed by their sensitivity to sialidases. These strains are able to bind the sialic acid found as a terminal moiety on the ganglioside GM3118,119 and as terminal and internal moieties on ganglioside GD1a.120 In contrast, sialidase-insensitive rotaviruses, which include most human strains, appear to interact with the ganglioside GM1a that lacks a terminal sialic acid.120 Of note, GM1a contains an internal sialic acid moiety that can interact with VP8*, and it is not affected by sialidases.
Exploring the biomedical potential of a novel modified glass ionomer cement against the pandrug-resistant oral pathogen Candida albicans SYN-01
Published in Journal of Oral Microbiology, 2023
Nessma A. El Zawawy, Samy El-Safty, El-Refaie Kenawy, Sara Ibrahim Salem, Sameh S. Ali, Yehia A.-G. Mahmoud
Neuraminidase, or sialidase, is an exoglycosidase hydrolyzing α-linkage of the terminal sialic acids of various sialoglycoconjugates in diverse organisms, including viruses and microorganisms [31]. This enzyme modifies cell-surface-located sialoglycoconjugates, which play important roles in the regulation of cell-to-cell and cell-to-molecule interactions by mediating cell recognition or adhesion processes [32]. Neuraminidases are widely expressed as virulence factors by several mucosal pathogens [33]. Surprisingly, recent evidence suggests that neuraminidase activity may influence biofilm formation [34]. Although neuraminidase production of some microorganisms was considered the main virulence factor to cause infections, the mechanism of fungal neuraminidase in dental caries is not clearly defined [35,36]. Thus, our study may be, up to the moment, the first to provide an insight into the role of fungal neuraminidase enzyme in dental infections.
Carbohydrates great and small, from dietary fiber to sialic acids: How glycans influence the gut microbiome and affect human health
Published in Gut Microbes, 2021
Joanna K Coker, Oriane Moyne, Dmitry A. Rodionov, Karsten Zengler
Human-associated bacteria, including gut microbiota, use sialic acids primarily as either a nutrient source or as a signaling molecule to interact with their host.95 For example, given the role of Neu5Ac on host cells in inhibiting autoimmune signaling through Siglec proteins,96 some pathogens evade the immune system by prominently displaying Neu5Ac on their cell surfaces.97,98 For an extensive review of sialic acids catabolism by human pathogens all over the body, we refer to ref. 87.98 Bacteria can synthesize sialic acids de novo or scavenge from the surrounding environment.72,95 Complete metabolism of sialic acids requires a sialidase to release the monosaccharide from the glycan, a transporter protein to transport the monosaccharide inside the cell, and a suite of intracellular enzymes to convert sialic acids into a sugar fed into different metabolic pathways (Figure 3B).72 Many common gut microbes contain genes for part of or for this entire pathway, affecting their role in the gut microbial community, and through that the community’s potential effects on human health.
TGF-β1 increases sialidase 3 expression in human lung epithelial cells by decreasing its degradation and upregulating its translation
Published in Experimental Lung Research, 2020
Wensheng Chen, Teresa M. Lamb, Richard H. Gomer
Pulmonary fibrosis is a chronic and generally fatal disorder characterized by progressive formation of scar-like tissue in the lungs. Despite some impressive advances, the fundamental mechanisms that cause pulmonary fibrosis are still unclear. Sialic acids are often found as the distal terminal sugar on glycoconjugates. Sialidases (also called neuraminidases) desialylate (remove the sialic acid from) glycoconjugates. Mammals have four sialidases, NEU1-NEU4. We found extensive desialylation of glycoconjugates and upregulation of NEU2 and NEU3 in fibrotic lesions in human and mouse lungs.1 We also found NEU3 upregulated in the BAL fluid from mice with bleomycin-induced pulmonary fibrosis. However, studies using microarrays of whole lung tissue mRNA and single cell RNA-seq found no significant difference in levels of NEU3 mRNA between IPF patients and controls.2,3 Since inhibiting NEU3 activity inhibits pulmonary fibrosis in the mouse bleomycin model,1 NEU3 appears to be a significant contributor to fibrosis. Determining how NEU3 is upregulated may help us understand basic mechanisms of fibrosis.