Disease relevance of Sialomucin

• The L11 antigen is CD43, a sialomucin implicated in vitro in regulation of lymphocyte activation, whose expression is often dysregulated in the Wiskott-Aldrich syndrome [1].
• Our results provide the first example of an essential role for a sialomucin in development and suggest that defects in podocalyxin could play a role in podocyte dysfunction in renal failure and omphalocele in humans [2].
• MAT-B1 and MAT-C1 ascites sublines of the 13762 rat mammary adenocarcinoma both contain sialomucin as a major cell surface component and are resistant to cytolysis by normal rat spleen lymphocytes [3 +/- 2% (SD) and 0 +/- 1%, respectively] [3].
• Sialomucin and lytic susceptibility of rat mammary tumor ascites cells [4].
• Complexity of MAM-6, an epithelial sialomucin associated with carcinomas [5].

High impact information on Sialomucin

• Binding of L-selectin to the vascular sialomucin CD34 [6].
• Amino acid sequencing of purified Sgp90 revealed a protein core identical to that CD34, a sialomucin expressed on hematopoietic stem cells and endothelium [6].
• Here, we have addressed this issue by examining the behavior of mutant mast cells lacking CD34, the related sialomucin, CD43, or both molecules [7].
• The sialomucin PSGL-1/CD162 mediates the attachment of mature leukocytes to P-selectin [8].
• Here, we identified a novel HEV-associated sialomucin, nepmucin (mucin not expressed in Peyer's patches [PPs]), that is expressed in LN HEVs but not detectable in PP HEVs at the protein level [9].

Chemical compound and disease context of Sialomucin

• Effect of tunicamycin on sialomucin and natural killer susceptibility of rat mammary tumor ascites cells [10].
• We have investigated the mechanism for the appearance of the disaccharide at the cell surface of ascites 13762 rat mammary adenocarcinoma cells using pulse-chase glucosamine labeling, proteolysis, and PNA precipitation of the cell-surface sialomucin ASGP-1 [11].
• The major cell surface glycoprotein (ascites sialoglycoprotein-1 (ASGP-1] of ascites 13762 rat mammary tumor cells is a large (Mr greater than 500,000), highly glycosylated sialomucin which is present in great abundance (greater than 0.5% of total cell protein) [12].
• However, in Salla disease the high NA signal may have a contribution from accumulated lysosomal NANA, which offsets the possible loss of NAA [13].
• Desialylation of human red blood cells (RBC) by Vibrio cholerae neuraminidase (VCN) was found to produce cells with electrophoretic properties which were inconsistent with the view of simple loss of N-acetylneuraminic acid (NANA) as the sole effect of VCN treatment [14].

Biological context of Sialomucin

• CD164 encodes a widely expressed cell surface sialomucin that has been implicated in regulation of cell proliferation and adhesion during hematopoiesis [15].
• The sialomucin CD164 (MGC-24v) is an adhesive glycoprotein expressed by human hematopoietic progenitors and bone marrow stromal cells that serves as a potent negative regulator of hematopoiesis [16].
• One such stem cell-associated antigen is the sialomucin CD34, a highly O-glycosylated cell surface glycoprotein that has also been shown to be expressed on all vascular endothelial cells throughout murine embryogenesis as well as in the adult [17].
• CD164, a novel sialomucin on CD34(+) and erythroid subsets, is located on human chromosome 6q21 [18].
• These results indicate that those epitopes are masked, probably due to cell line- or possibly cell type-dependent variations in glycosylation of the epithelial sialomucin [5].

Anatomical context of Sialomucin

• Nepmucin, a novel HEV sialomucin, mediates L-selectin-dependent lymphocyte rolling and promotes lymphocyte adhesion under flow [9].
• The interaction of L-selectin expressed on lymphocytes with sulfated sialomucin ligands such as CD34 and GlyCAM-1 on high endothelial venules (HEV) of lymph nodes results in lymphocyte rolling and is essential for lymphocyte recruitment [19].
• P-selectin glycoprotein ligand 1 (PSGL-1) is a sialomucin expressed on leukocytes that mediates neutrophil rolling on the vascular endothelium [20].
• The results showed a progressive increase in sialomucin staining in normal-appearing mucosa in distal colon and rectum in both groups but not in the proximal colon [21].
• Clones were examined for formation of acinus-like spheres, deposition of basement membrane components, production of sialomucin, polarization, and growth arrest [22].

Associations of Sialomucin with other chemical compounds

• A sialomucin molecule identical or closely related to P selectin glycoprotein ligand-1 (PSGL-1), the major P selectin ligand on neutrophils and HL-60 cells, appears to be a major T cell ligand for P selectin [23].
• One of the major characteristics of HEV endothelial cells (HEVEC) is their capacity to incorporate large amounts of sulfate into sialomucin-type counter-receptors for the lymphocyte homing receptor L-selectin [24].
• Sections of mature spheres revealed a central lumen surrounded by polarized luminal epithelial cells expressing keratins 18 and 19 and sialomucin at the apical membrane [25].
• N-Acetylglucosamine at a concentration of 20 mmol/L almost completely inhibited WGA-induced CL production by neutrophils, whereas bovine submaxillary gland mucin, a potent blocker of NANA binding of WGA, failed to inhibit CL production [26].
• Because human CD34+ and murine Sca-1+ hematopoietic stem-progenitor cells (HSPCs) express platelet-binding sialomucin P-selectin (CD162) and integrin Mac-1 (CD11b-CD18) antigen, it was inferred that these cells might interact with platelets [27].

Gene context of Sialomucin

• Neutralizing antibody to endothelial-associated E-selectin (a ligand for sialyl Le(x)) inhibited adhesion of metastatic cells to cytokine-activated hepatic endothelial cells, and inhibition of sialomucin with antisense to the MUC2 gene inhibited adhesion to E-selectin [28].
• Overexpression of sialomucin complex, a rat homologue of MUC4, inhibits tumor killing by lymphokine-activated killer cells [29].
• [3H]Glucosamine pulse-chase labeling studies using antibodies specific for a COOH-terminal unglycosylated region of the MUC1 mucin core peptides suggested that NCCM treatment of HT-29 LMM cells did not change the rate of MUC1-related sialomucin processing [30].
• PEA3 transactivates the Muc4/sialomucin complex promoter in mammary epithelial and tumor cells [31].
• Molecular cloning of a cDNA encoding CD34, a sialomucin of human hematopoietic stem cells [32].

Analytical, diagnostic and therapeutic context of Sialomucin

• One week after treatment the crypts of the carcinogen-treated explants showed an increase in sialomucin, and by 9 weeks after treatment, they showed mostly sialomucin [33].
• Biochemical characterization and molecular cloning of a novel endothelial-specific sialomucin [34].
• Western blots of elastase-treated neutrophils detected an 83-kD CD43 fragment that, together with the released 52-kD fragment and 40-kD subfragment, accounts for the entire molecule and indicates that CD43 is cleaved at two sites only, releasing the distal approximately 40% of the sialomucin region [35].
• Pulse-chase labeling with 35S-labeled amino acids followed by immunoprecipitation with anti-ASGP-2 indicated a precursor-product relationship for the Mr = 400,000 component, designated pSMC-1 (precursor, sialomucin complex), and ASGP-2 [36].
• Using a combination of flow cytometry and immunoprecipitation techniques, we identified the sialomucin CD43 as a counterreceptor for trans-sialidase on CD4(+) T cells [37].

References