Published: June 14th, 2016
Mucins are high-molecular-weight glycoconjugates, with size ranging from 0.2 to 200 megadalton (MDa). As a result of their size, mucins do not penetrate conventional polyacrylamide gels and require larger pores for separation. We provide a detailed protocol for mucin agarose gel electrophoresis to assess relative quantification and study polymer assembly.
Mucins, the heavily-glycosylated proteins lining mucosal surfaces, have evolved as a key component of innate defense by protecting the epithelium against invading pathogens. The main role of these macromolecules is to facilitate particle trapping and clearance while promoting lubrication of the mucosa. During protein synthesis, mucins undergo intense O-glycosylation and multimerization, which dramatically increase the mass and size of these molecules. These post-translational modifications are critical for the viscoelastic properties of mucus. As a result of the complex biochemical and biophysical nature of these molecules, working with mucins provides many challenges that cannot be overcome by conventional protein analysis methods. For instance, their high-molecular-weight prevents electrophoretic migration via regular polyacrylamide gels and their sticky nature causes adhesion to experimental tubing. However, investigating the role of mucins in health (e.g., maintaining mucosal integrity) and disease (e.g., hyperconcentration, mucostasis, cancer) has recently gained interest and mucins are being investigated as a therapeutic target. A better understanding of the production and function of mucin macromolecules may lead to novel pharmaceutical approaches, e.g., inhibitors of mucin granule exocytosis and/or mucolytic agents. Therefore, consistent and reliable protocols to investigate mucin biology are critical for scientific advancement. Here, we describe conventional methods to separate mucin macromolecules by electrophoresis using an agarose gel, transfer protein into nitrocellulose membrane, and detect signal with mucin-specific antibodies as well as infrared fluorescent gel reader. These techniques are widely applicable to determine mucin quantitation, multimerization and to test the effects of pharmacological compounds on mucins.
Mucins are normally produced by mucosal surfaces that line cavities exposed to the external environment (e.g., respiratory, digestive, reproductive tracts, ocular surface) as well as internal organs (e.g., pancreas, gallbladder, mammary glands). The presence of these glycoproteins maintains surface hydration and forms a physical barrier against pathogens. Although mucin production is essential to mucosal health, mucin hyperconcentration and/or aberrant mucus properties can lead to duct obstruction, bacterial colonization and chronic inflammation, which can cause irreversible tissue damage. A similar cascade of events are observed in several diseases,....
1. Prepare Buffers for Mucin Gel Western Blotting
We show representative results of mucin expression following agarose gel electrophoresis in BALF from the lungs of mice (Figure 1). In this example, we used the agarose gel to show upregulation of mucin production following IL-13 treatment of the Tg-Muc5ac mouse model. The Western blot shows a visual representation of mucin expression, which can be used for a quantitative analysis of multimer or monomer band signal intensity (Figure 2). This method can al.......
The protocol of mucin Western blotting described in this video combines conventional techniques used in molecular biology to separate and transfer large macromolecules, such as DNA, with regular techniques for protein detection, i.e., immunoblotting. The same technique could be applied to study the biology of complex glycosaminoglycans, such as the breakdown of high-molecular-weight hyaluronic acid18. Although this technique could be used in a broad range of assays, successful agarose Western blotting.......
The authors would like to acknowledge Dr. John Sheehan and Dr. Lubna Abdullah for their guidance and mentoring that were central in the completion of this work. This work was supported by funds from the National Institutes of Health (P01HL108808, UH2HL123645) and the Cystic Fibrosis Foundation Therapeutics, Inc. (EHRE07XX0). Kathryn Ramsey is supported by an NHMRC Early Career Research fellowship.....
|Glacial Acetic Acid
|SDS (Sodium Dodecyl Sulfate)
|20X SSC (Sodium Saline Citrate) Buffer
|Trisodium Citrate (Na3C6H5O7)
|10 mM DTT (dithiothreitol)
|Instant non-fat dry milk
|Dulbecco Phosphate Buffered Saline (D-PBS)
|Anti-GFP Goat Primary Antibody (mouse samples)
|Rockland antibodies and assays
|UNC 222 Anti-Muc5b Rabbit Primary Antibody (mouse samples)
|H300 Anti-MUC5B Primary Antibodies (human samples)
|45M1 Anti-MUC5AC Primary Antibodies (human samples)
|Donkey Anti-rabbit 800CW IR Dye
|Donkey Anti-mouse 680LT IR Dye
|Electrophoresis Gel Box and Casting Tray
|Owl Seperation Systems
|Power Supply Box
|Membrane Blotting Paper
|Whatman Paper and Nitrocellulose membrane
|10 439 196
|Boekel/Appligene Vacuum Blotter 230v
|Odyssey Infrared Fluorescence System
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