Role Of Mucins Research Articles

The histopathology of mucins

Advances in our understanding of the role of mucins in health and disease have been almost entirely derived from work in the gastrointestinal tract. This work has led to the re-evaluation and rationalization of older histological staining techniques, and to the development and critical evaluation of new techniques. This short review concentrates firstly on these technical advances and, secondly, on their application to the understanding of gastrointestinal mucins and to routine clinical practice

The role of mucin in colon-cancer metastasis.

Mucinous colorectal cancer often presents at an advanced stage. We have previously observed that mucin production by human colon-cancer cells correlates with their ability to colonize the liver in experimental animal models. The present study was undertaken in order to further elucidate the mechanisms by which production of mucin by colon-cancer cells affects metastasis. Cell lines showing high mucin production (HMP) (HM 7, HM 3 and LS LiM 6) demonstrated increased adherence to basement membrane proteins and invaded a reconstituted basement membrane to a greater extent than their counter-part cell lines showing low mucin production (LMP) (LS174T and LM 12). Adherence of the LMP parental cell line LS174T to various matrix proteins was potentiated by the addition of purified human colon-cancer mucin in a dose-dependent fashion. HMP cell lines secreted more proteolytically active type-IV collagenase than LMP lines, and collagenase activity was further stimulated by purified mucin in a dose-dependent manner. Specific inhibition of mucin O-glycosylation by benzyl-alpha-N-acetylgalactosamine significantly affected each of the metastasis-related events, with the greatest effect on the HMP cell lines. The present data further indicate that mucin may play an important role in the metastatic process.

A role for mucin in the absorption of inorganic iron and other metal cations: A study in rats

The steps involved in iron absorption are poorly understood. Although transferrin and ferritin are water soluble, most radioiron in gut homogenates after an intraluminal dose of radioiron is recovered in water-insoluble precipitates. Most radioiron in the precipitates was insoluble in detergents and organic solvents and was characterized as mucins. These isolates bound iron in vitro with a Kd of 9.09 × 10−5. Similar iron binding was observed with commercial mucins. Iron binding to mucin occurred at acid pH and maintained the iron available for absorption with alkalinization. Similar pH-dependent binding to mucin was observed with zinc, cobalt, and lead. Iron competitively inhibited binding of these metals to mucin. However, iron chelates of ascorbate, fructose, and histidine donated iron to mucin at neutral pH. These data provided a role for gastric HCl and intestinal mucin in absorption of iron and metal cations and partial explanation of the competition for absorption between certain metals from the gut lumen. It is postulated that intestinal mucin delivers inorganic iron to intestinal absorptive cells in an acceptable form for absorption.

A role for mucin in the absorption of inorganic iron and other metal cations

Abstract The steps involved in iron absorption are poorly understood. Although transferrin and ferritin are water soluble, most radioiron in gut homogenates after an intraluminal dose of radioiron is recovered in water-insoluble precipitates. Most radioiron in the precipitates was insoluble in detergents and organic solvents and was characterized as mucins. These isolates bound iron in vitro with a Kd of 9.09 × 10 −5 . Similar iron binding was observed with commercial mucins. Iron binding to mucin occurred at acid pH and maintained the iron available for absorption with alkalinization. Similar pH-dependent binding to mucin was observed with zinc, cobalt, and lead. Iron competitively inhibited binding of these metals to mucin. However, iron chelates of ascorbate, fructose, and histidine donated iron to mucin at neutral pH. These data provided a role for gastric HCl and intestinal mucin in absorption of iron and metal cations and partial explanation of the competition for absorption between certain metals from the gut lumen. It is postulated that intestinal mucin delivers inorganic iron to intestinal absorptive cells in an acceptable form for absorption.

Inhibition ofHelicobacter pylorihaemogglutination activity by human salivary mucins

Thirty isolates of Helicobacter pylori from gastric biopsies agglutinated human erythrocyte suspensions. Crude mucin preparations derived from saliva of 20 different donors were examined for their ability to inhibit haemagglutination. All mucin preparations exhibited strong inhibitory activity. Removal of sialic residues from mucin preparations by treatment with neuraminidase resulted in a substantial reduction of their inhibitory activity. The mucin preparations had no bactericidal or aggregation activity for H. pylori. These results are discussed in the context of the role of mucins in colonization of the gastric mucosa by H. pylori.

Ultrastructural localization of secretory glycoconjugates in the gallbladder epithelium of the Richardson’s ground squirrel before and during cholesterol gallstone formation

Hypersecretion of mucin is a critical feature of gallbladder epithelial cells in ground squirrels fed a 2% cholesterol-enriched diet for the induction of cholesterol gallstone formation. The timing of this physiological response indicates a potential role for mucin as an initiator of cholesterol crystal nucleation from supersaturated bile. There is little information regarding the specific type of glycoprotein secreted by gallbladder epithelia and routine light microscope histochemistry proved unproductive for detection of specific glycoprotein types being synthesized as the intracellular accumulations were not large enough to permit visualization of a colored precipitate. Ultrastructural histochemistry was utilized to differentiate between the two main mucin types secreted by the gastrointestinal tract - sulphated and sialomucins.Two ultrastructural methods utilizing the histochemical basis of the high and low iron diamine techniques were used. The high iron diamine (HID) technique imparts density to sulphated complex carbohydrates while the low iron diamine (LID) method imparts density to acidic glycoconjugates.

Transmural calcium fluxes and role of mucins as cellular calcium‐transport vehicles in chicken trachea in vitro.

1. Transmural Ca2+ fluxes in tracheal tissue under physiological [Ca2+] conditions and the effect of altered serosal and luminal [Ca2+] on Ca2+ movements were investigated using chicken tracheal preparations in vitro. 2. In the presence of physiological [Ca2+] (1.8 mM), there was unidirectional Ca2+ flux with a small but steady uptake of Ca2+ from the serosal side into the submucosa followed by Ca2+ transport into the mucosa and then Ca2+ efflux into the tracheal lumen. The Ca2+ uptake by the tracheal tissue was via a diffusion process. There was no evidence of Ca2+ uptake via slow Ca2+ channels or Na+-Ca2+ exchange pathways. On the other hand, Ca2+ uptake from the lumen into the mucosa and Ca2+ efflux from the submucosa into the serosal side were almost negligible. 3. High serosal [Ca2+] (18.0 mM) and/or low luminal [Ca2+] (0.18 mM) increased significantly both Ca2+ uptake by the tissue from its serosal side and Ca2+ efflux into the lumen. Directional Ca2+ effect appeared to increase Ca2+ uptake via a diffusion process. 4. Transport of Ca2+ from the mucosa into the lumen comprised efflux of both filterable and mucin-bound forms of Ca2+. Under physiological [Ca2+] conditions, whilst initial efflux rates of both filterable and mucin-bound Ca2+ were almost equal, the net efflux of Ca2+ in mucin-bound form after 10 min was about 33% higher than that of filterable Ca2+. Similarly, the increase in Ca2+ efflux as a result of high serosal [Ca2+] involved a significant increase in the efflux of mucin-bound Ca2+ only, whereas the increased Ca2+ efflux as a result of low luminal [Ca2+] involved a significant increase in efflux of both filterable and mucin-bound Ca2+. 5. The transport of Ca2+ from the mucosa into the lumen in the form of mucin-bound Ca2+ appeared to play a significant role in the regulation of Ca2+ efflux from the tissue under increased Ca2+ influx or efflux conditions resulting from interventions with serosal and luminal [Ca2+]. 6. A concurrent stimulation of secretion of unique low molecular weight sulphate-rich components and high molecular weight mucin complexes with increased Ca2+ influx into and efflux from the tracheal tissue in response to high serosal and low luminal [Ca2+] allude to a plausible role of these secretory macromolecular mucin complexes as cellular Ca2+ transport vehicles.

Role of mucins from human whole saliva in the protection of tooth enamel against demineralization in vitro.

The influence of salivary pellicles on the demineralization of human dental enamel by 1% citric acid was studied. The pellicles were formed on embedded human tooth surfaces incubated in vitro with various solutions for periods of up to 6 days. Pellicles induced by unstimulated whole saliva gave an approximately 45% and those from parotid saliva a 25% inhibition of demineralization. On the other hand, a pellicle formed from mixed submandibular and sublingual (SM-SL) saliva in 30 min gave a retardation in lesion formation of at least 40% and after a 60-min exposure to SM-SL saliva, the lesion formation was completely prevented. In contrast, when the mucins were removed from SM-SL saliva by ultracentrifugation, protection against demineralization by the pellicle formed on exposure to the supernatant was only 30%. The effect of pellicles obtained by isolated salivary mucins was also studied. Human whole salivary mucins (HWSM) were isolated from both human SM-SL saliva and whole saliva of two individuals with blood group A. The mucins contained 18% protein, 72% carbohydrate, 1.4% sulfate and 0.14% phosphate. The major components of the protein moiety were threonine (14.7%), valine (12.6%) and serine (10.8%). The molar ratio of the sugar residues was: galactose: N-acetylglucosamine: N-acetylgalactose: fucose: N-acetylneuraminic acid = 6:4.5:4:7:1. A pellicle formed by a 3-day exposure to salivary mucins in vitro gave 100% protection of the tooth surface against demineralization by citric acid. These data suggest that the mucins in human saliva contribute to a large extent to its protective effect against acidic attacks on the tooth surface.

Role of mucin and albumin in saline polarization of dental amalgam

Studies into the electrochemical nature and corrosion behaviour of dental amalgam have indicated the need for an artificial saliva formula that will accurately simulate the electrochemical properties of natural saliva. Existing formulae have been based on inorganic saliva constituent concentrations, without accurate representation of organic constituents. Albumin and mucin were added to several dilutions of saline solution. The resulting solutions were used as electrolyte at 4 degrees and 37 degrees C for the potentiostatic anodic polarization of conventional amalgam. The presence of albumin and mucin did not appear to alter the major characteristics of corrosion profile. Examination of the current-time transient curves indicated, however, that the kinetics of the electrochemical reactions were delayed. Also, the open circuit potential was observed to shift to more active values with the addition of organic constituents, thereby creating a low current density region in the initial segment of the polarization profile.

The role of mucin in enhancing the infectious process.

Annals of the New York Academy of SciencesVolume 106, Issue 2 p. 680-682 THE ROLE OF MUCIN IN ENHANCING THE INFECTIOUS PROCESS George H. Scherr, George H. Scherr Research Division, Consolidated Laboratories, Inc., Chicago Heights, Ill.Search for more papers by this author George H. Scherr, George H. Scherr Research Division, Consolidated Laboratories, Inc., Chicago Heights, Ill.Search for more papers by this author First published: March 1963 https://doi.org/10.1111/j.1749-6632.1963.tb16675.xCitations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume106, Issue2Mucous SecretionsMarch 1963Pages 680-682 RelatedInformation

On the Role of Mucin in the Pathogenesis of Caries

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