-
FASEB Journal : Official Publication of... Feb 2020Many members of the mucin family are evolutionarily conserved and are often aberrantly expressed and glycosylated in various benign and malignant pathologies leading to...
Many members of the mucin family are evolutionarily conserved and are often aberrantly expressed and glycosylated in various benign and malignant pathologies leading to tumor invasion, metastasis, and immune evasion. The large size and extensive glycosylation present challenges to study the mucin structure using traditional methods, including crystallography. We offer the hypothesis that the functional versatility of mucins may be attributed to the presence of intrinsically disordered regions (IDRs) that provide dynamism and flexibility and that the IDRs offer potential therapeutic targets. Herein, we examined the links between the mucin structure and function based on IDRs, posttranslational modifications (PTMs), and potential impact on their interactome. Using sequence-based bioinformatics tools, we observed that mucins are predicted to be moderately (20%-40%) to highly (>40%) disordered and many conserved mucin domains could be disordered. Phosphorylation sites overlap with IDRs throughout the mucin sequences. Additionally, the majority of predicted O- and N- glycosylation sites in the tandem repeat regions occur within IDRs and these IDRs contain a large number of functional motifs, that is, molecular recognition features (MoRFs), which directly influence protein-protein interactions (PPIs). This investigation provides a novel perspective and offers an insight into the complexity and dynamic nature of mucins.
Topics: Glycosylation; Humans; Models, Molecular; Mucins; Protein Domains; Sequence Analysis, Protein; Structure-Activity Relationship
PubMed: 31908009
DOI: 10.1096/fj.201901898RR -
Glycobiology Dec 2014Vascular endothelial cells, in addition to many other mammalian cell types, express proteins that are highly modified with mucin-type O-glycosylation, a specific type of... (Review)
Review
Vascular endothelial cells, in addition to many other mammalian cell types, express proteins that are highly modified with mucin-type O-glycosylation, a specific type of glycosylation that begins with the addition of an N-acetylgalactosamine moiety to serine or threonine residues within the peptide backbone. Recently, it has become evident that O-glycosylation governs the separation of blood and lymphatic vessels throughout life and plays a critical role in maintaining vascular integrity in specific tissues such as the brain and lymph node. This mini-review seeks to highlight some of these recent advances regarding in vivo functions of mucin-type O-glycans.
Topics: Animals; Endothelium, Vascular; Glycosylation; Humans; Mucins; Polysaccharides
PubMed: 24946788
DOI: 10.1093/glycob/cwu058 -
American Journal of Respiratory Cell... Feb 2007Mucus secretions have played a central role in the evolution of multicellular organisms, enabling adaptation to widely differing environments. In vertebrates, mucus... (Review)
Review
Mucus secretions have played a central role in the evolution of multicellular organisms, enabling adaptation to widely differing environments. In vertebrates, mucus covers and protects the epithelial cells in the respiratory, gastrointestinal, urogenital, visual, and auditory systems, amphibian's epidermis, and the gills in fishes. Deregulation of mucus production and/or composition has important consequences for human health. For example, mucus obstruction of small airways is observed in chronic airway diseases, including chronic obstructive pulmonary disease, asthma, and cystic fibrosis. The major protein component in the mucus is a family of large, disulfide-bonded glycoproteins known as gel-forming mucins. These proteins are accumulated in large, regulated secretory granules (the mucin granules) that occupy most of the apical cytoplasm of specialized cells known as mucous/goblet cells. Since mucin oligomers have contour dimensions larger than the mucin granule average diameter, the question arises how these highly hydrophilic macromolecules are organized within these organelles. I review here the intraluminal organization of the mucin granule in view of our knowledge on the structure, biosynthesis, and biophysical properties of gel-forming mucins, and novel imaging studies in living mucous/goblet cells. The emerging concept is that the mucin granule lumen comprises a partially condensed matrix meshwork embedded in a fluid phase where proteins slowly diffuse.
Topics: Animals; Cystic Fibrosis Transmembrane Conductance Regulator; Extracellular Matrix; Goblet Cells; Humans; Mucins; Protein Transport; Secretory Vesicles
PubMed: 16960124
DOI: 10.1165/rcmb.2006-0291TR -
International Journal of Medical... 2017Pseudomyxoma peritonei (PMP) is a rare disease with excess intraperitoneal mucin secretion. Treatment involves laparotomy, cytoreduction and chemotherapy that is very...
Pseudomyxoma peritonei (PMP) is a rare disease with excess intraperitoneal mucin secretion. Treatment involves laparotomy, cytoreduction and chemotherapy that is very invasive with patients often acquiring numerous compromises. Hence a mucolytic comprising of bromelain and N-acetyl cystein has been developed to solubilise mucin in situ for removal by catherization. Owing to differences in mucin appearance and hardness, dissolution varies. Therefore the current study investigates the inter-mucin physical and chemical characteristics, in order to reformulate an effective mucolytic for all mucin. PMP mucin, from the three categories (soft, semi hard and hard mucin) was solubilised and then various physical characteristics such as turbidity, density, kinematic viscosity were measured. The water content and the density of solid mucin were also determined. This was followed by the determination of sialic acid, glucose, lipid, Thiol (S-S and S-H) content of the samples. Lastly, the distribution of MUC2, MUC5B and MUC5AC was determined using western blot technique. Both turbidity and kinematic viscosity and sialic acid content increased linearly as the hardness of mucin increased. However, density, hydration, protein, glucose, lipid and sulfhydryl and disulphide content decreased linearly as hardness of mucin increased. The distribution ratio of mucins (MUC2:MUC5B:MUC5AC) in soft mucin is 2.25:1.5:1.0, semi hard mucin is 1:1:1 and hard mucin is 3:2:1. The difference in texture and hardness of mucin may be due to cellular content, hydration, glucose, protein, lipids, thiol and MUC distribution. Soft mucin is solely made of glycoprotein whilst the others contained cellular materials.
Topics: Glucose; Humans; Lipids; Mucin 5AC; Mucin-2; Mucin-5B; Mucins; Mucus; N-Acetylneuraminic Acid; Peritoneal Neoplasms; Pseudomyxoma Peritonei; Sulfhydryl Compounds; Viscosity
PubMed: 28138305
DOI: 10.7150/ijms.16422 -
Biochemical Society Transactions Jun 2018In humans and mice, the first line of innate defense against inhaled pathogens and particles in the respiratory tract is airway mucus. The primary solid components of... (Review)
Review
In humans and mice, the first line of innate defense against inhaled pathogens and particles in the respiratory tract is airway mucus. The primary solid components of the mucus layer are the mucins MUC5AC and MUC5B, polymeric glycoproteins whose changes in abundance and structure can dramatically affect airway defense. Accordingly, and are tightly regulated at a transcriptional level by tissue-specific transcription factors in homeostasis and in response to injurious and inflammatory triggers. In addition to modulated levels of mucin gene transcription, translational and post-translational biosynthetic processes also exert significant influence upon mucin function. Mucins are massive macromolecules with numerous functional domains that contribute to their structural composition and biophysical properties. Single MUC5AC and MUC5B apoproteins have molecular masses of >400 kDa, and von Willebrand factor D-like as well as other cysteine-rich domain segments contribute to mucin polymerization and flexibility, thus increasing apoprotein length and complexity. Additional domains serve as sites for O-glycosylation, which increase further mucin mass several-fold. Glycosylation is a defining process for mucins that is specific with respect to additions of glycans to mucin apoprotein backbones, and glycan additions influence the physical properties of the mucins via structural modifications as well as charge interactions. Ultimately, through their tight regulation and complex assembly, airway mucins follow the biological rule of 'form fits function' in that their structural organization influences their role in lung homeostatic mechanisms.
Topics: Animals; Gene Expression Regulation; Homeostasis; Humans; Inflammation; Lung; Mucins; Transcription, Genetic
PubMed: 29802217
DOI: 10.1042/BST20170455 -
Biochimie Jun 2013Mucins belong to a heterogeneous family of large O-glycoproteins composed of a long peptidic chain called apomucin on which are linked hundreds of oligosaccharidic... (Review)
Review
Mucins belong to a heterogeneous family of large O-glycoproteins composed of a long peptidic chain called apomucin on which are linked hundreds of oligosaccharidic chains. Among mucins, membrane-bound mucins are modular proteins and have a structural organization usually containing Pro/Thr/Ser-rich O-glycosylated domains (PTS), EGF-like and SEA domains. Via these modular domains, the membrane-bound mucins participate in cell signalling and cell interaction with their environment in normal and pathological conditions. Moreover, the recent knowledge of these domains and their biological activities led to the development of new therapeutic approaches involving mucins. In this review, we show 3D structures of EGF and SEA domains. We also describe the functional features of the evolutionary conserved domains of membrane-bound mucins and discuss consequences of splice events.
Topics: Animals; Biological Evolution; Humans; Mucins; Protein Structure, Tertiary
PubMed: 23178705
DOI: 10.1016/j.biochi.2012.11.005 -
The International Journal of... Jul 2014Our current understanding of cystic fibrosis (CF) has revealed that the biophysical properties of mucus play a considerable role in the pathogenesis of the disease in... (Review)
Review
Our current understanding of cystic fibrosis (CF) has revealed that the biophysical properties of mucus play a considerable role in the pathogenesis of the disease in view of the fact that most mucus-producing organs are affected in CF patients. In this review, we discuss the potential causal relationship between altered cystic fibrosis transmembrane conductance regulator (CFTR) function and the production of mucus with abnormal biophysical properties in the intestine and lungs, highlighting what has been learned from cell cultures and animal models that mimic CF pathogenesis. A similar cascade of events, including mucus obstruction, infection and inflammation, is common to all epithelia affected by impaired surface hydration. Hence, the main structural components of mucus, namely the polymeric, gel-forming mucins, are critical to the onset of the disease. Defective CFTR leads to epithelial surface dehydration, altered pH/electrolyte composition and mucin concentration. Further, it can influence mucin transition from the intracellular to extracellular environment, potentially resulting in aberrant mucus gel formation. While defective HCO3(-) production has long been identified as a feature of CF, it has only recently been considered as a key player in the transition phase of mucins. We conclude by examining the influence of mucins on the biophysical properties of CF sputum and discuss existing and novel therapies aimed at removing mucus from the lungs. This article is part of a Directed Issue entitled: Cystic Fibrosis: From o-mics to cell biology, physiology, and therapeutic advances.
Topics: Animals; Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; Humans; Mucins
PubMed: 24685676
DOI: 10.1016/j.biocel.2014.03.011 -
American Journal of Respiratory and... Apr 2022
Topics: Humans; Lung; Mucin-5B; Mucins
PubMed: 35148488
DOI: 10.1164/rccm.202201-0064ED -
Biotechnology and Bioengineering May 2019Optimization of host-cell production systems with improved yield and production reliability is desired to meet the increasing demand for biologics with complex...
Optimization of host-cell production systems with improved yield and production reliability is desired to meet the increasing demand for biologics with complex posttranslational modifications. Aggregation of suspension-adapted mammalian cells remains a significant problem that can limit the cellular density and per volume yield of bioreactors. Here, we propose a genetically encoded technology that directs the synthesis of antiadhesive and protective coatings on the cellular surface. Inspired by the natural ability of mucin glycoproteins to resist cellular adhesion and hydrate and protect cell and tissue surfaces, we genetically encode new cell-surface coatings through the fusion of engineered mucin domains to synthetic transmembrane anchors. Combined with appropriate expression systems, the mucin-coating technology directs the assembly of thick, highly hydrated barriers to strongly mitigate cell aggregation and protect cells in suspension against fluid shear stresses. The coating technology is demonstrated on suspension-adapted human 293-F cells, which resist clumping even in media formulations that otherwise would induce extreme cell aggregation and show improved performance over a commercially available anticlumping agent. The stable biopolymer coatings do not show deleterious effects on cell proliferation rate, efficiency of transient transfection with complementary DNAs, or recombinant protein expression. Overall, our mucin-coating technology and engineered cell lines have the potential to improve the single-cell growth and viability of suspended cells in bioreactors.
Topics: Bioreactors; Cell Aggregation; Cell Count; Cell Line; Cell Proliferation; Humans; Mucins; Recombinant Proteins
PubMed: 30636317
DOI: 10.1002/bit.26916 -
Cancer Reports (Hoboken, N.J.) Aug 2022Breast cancer is a very common cancer that can be severe if not discovered early. The current tools to detect breast cancer need improvement. Cancer has a universal...
BACKGROUND
Breast cancer is a very common cancer that can be severe if not discovered early. The current tools to detect breast cancer need improvement. Cancer has a universal tendency to affect glycosylation. The glycosylation of circulating extracellular vesicle-associated glycoproteins, and mucins may offer targets for detection methods and have been only explored in a limited capacity.
AIM
Our aim was to develop an approach to detect the aberrant glycosylation of mucins and extracellular vesicle-associated glycoproteins from human sera using fluorescent nanoparticles, and preliminarily evaluate this approach for the differential diagnosis of breast cancer.
METHODS AND RESULTS
The assay involved immobilizing glycosylated antigens using monoclonal antibodies and then probing their glycosylation by using lectins and glycan-specific antibodies coated on Eu -doped nanoparticles. Detection of mucin 1 and mucin 16 glycosylation with wheat germ agglutinin, and detection of the extracellular vesicle-associated CD63 were found to have better diagnostic ability for localized breast cancer than the conventional assays for mucin 1 and mucin 16 based tumor markers when the receiver operating characteristics were compared.
CONCLUSIONS
These results indicate that successful differential diagnosis of primary breast cancer may be aided by detecting cancer-associated glycosylation of mucin 1 and mucin 16, and total concentration of CD63, in human serum.
Topics: Biomarkers, Tumor; Breast Neoplasms; CA-125 Antigen; Extracellular Vesicles; Female; Glycoproteins; Glycosylation; Humans; Mucin-1; Mucins
PubMed: 34423573
DOI: 10.1002/cnr2.1540