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.

1. Prepare Buffers for Mucin Gel Western Blotting
<ol>
	<li>Prepare 1 liter of 50x TAE (Tris-acetate-EDTA) buffer.
	<ol>
		<li>In 700 ml of distilled water (dH2O) add 242 g of Tris base (0.4 M), 57.1 g of glacial acetic acid (weigh liquid) (0.2 M) and 14.61 g of ethylenediaminetetraacetic acid (EDTA) (50 mM).</li>
		<li>Adjust pH to 8.0 and make the volume up to 1 liter with dH2O.</li>
	</ol>
	</li>
	<li>Prepare 10 ml of 10x loading buffer.
	<ol>
		<li>Prepare 5 ml of 1x TAE buffer. To do this, add 5 ml of glycerol (50%), 25 mg of bromophenol blue (0.25%), and 100 mg of sodium dodecyl sulfate (SDS) (1%).</li>
	</ol>
	</li>
	<li>Prepare 2 liters of 20x sodium saline citrate (SSC) buffer.
	<ol>
		<li>In 1.5 liters of dH2O, add 350.6 g of NaCl (3 M) and 176.4 g of trisodium citrate (Na3C6H5O7) (0.3 M). Adjust pH to 7.0 and make up the volume to 2 liters with dH2O.</li>
	</ol>
	</li>
	<li>Prepare 1 liter of 1x TAE-0.1% SDS buffer.
	<ol>
		<li>Add 20 ml of 50x TAE to 980 ml of dH2O. Add 1 g of SDS to make a 0.1% SDS-TAE solution.</li>
	</ol>
	</li>
</ol>
2. TAE-SDS Agarose Gel Preparation
<ol>
	<li>Pour sufficient volume (i.e., 150 ml) of 1x TAE-0.1% SDS buffer in a microwavable Erlenmeyer flask to make a 5 - 7 mm-thick gel. Add 0.8% (1.2 g) agarose powder.</li>
	<li>Microwave flask in 30 sec intervals with intermittent swirling until agarose is completely dissolved (usually 1 - 3 min). Use hot hand pads during this process. Be careful of eruptive boiling while swirling.</li>
	<li>Allow the agarose solution to cool down for 5 - 10 min. Note: The agarose solution will be ready to be poured when bottom of the flask can be left on the palm for 5 sec.</li>
	<li>Prepare electrophoresis casting tray (10 x 15 cm) by sealing the edges with tape and placing well comb in position.</li>
	<li>Pour agarose solution slowly in the casting tray to avoid the formation of bubbles. Remove bubbles using a pipette tip. Wait for the gel to cool and completely solidify. Once solidified, remove the comb slowly to avoid collapsing the wells by suction and remove the tape from the edges of the tray.</li>
	<li>Place agarose gel into the gel box and fill the electrophoresis unit with 1x TAE-0.1% SDS buffer until the gel is fully covered.</li>
</ol>
3. Sample Loading and Electrophoresis Separation
Note: In our laboratory, we commonly use samples from both mouse and humans, including bronchoalveolar lavage fluid (BALF; both species), cell washings from human bronchial epithelial cells (HBE), and human saliva and sputum samples. Samples can be denatured in 6 M urea upon collection or stored for short periods of time (6 hr) by adding proteinase cocktail inhibitor.&#160;
<ol>
	<li>Prepare samples for loading by adding 10% of loading dye to each sample (i.e., 30 &#181;l of sample and 3 &#181;l of dye). Homogenize samples by pipetting up and down. Briefly spin down tubes at 5,000 rpm to collect droplets.</li>
	<li>Carefully load equal volume of samples into the wells.
	<ol>
		<li>Pre-wet tips and/or use positive displacement pipettes to facilitate loading of highly viscous samples. Slowly aspirate 80 - 90% of sample-dye solution (i.e., 27 - 30 &#181;l) to avoid pipetting bubbles.</li>
		<li>Slowly load at the bottom of the wells and progressively move the pipet tip upward. For samples that remain attached to the pipette tip, dispense at a 45&#176; angle and elongate straight above the well or gently use the side of the well to break the stringy mucus. Do not overload the wells.</li>
	</ol>
	</li>
	<li>Connect the electrodes from the gel box to the electrophoresis power generator. Ensure the electrodes are connected properly (i.e., red lead plugged to the positive output of the generator) to allow negatively charged mucins to run towards the positive electrode.</li>
	<li>Run the gel at 80 Volts for 90 min for a single comb gel, or 60 - 75 min for a double comb gel to prevent overlap between the two rows.</li>
	<li>Turn generator power OFF and disconnect the electrodes from the power source.</li>
	<li>Carefully remove the gel from the gel box with one hand on either side of the casting tray to ensure the gel remains in place.</li>
</ol>
4. Reduce Agarose Gel for Efficient Mucin Transfer
<ol>
	<li>Carefully place the gel flat in a glass container. Rinse the gel with dH2O to remove traces of TAE-SDS buffer.</li>
	<li>Prepare 1 liter of 4x SSC buffer by adding 200 ml of 20x SSC into 800 ml of dH2O. Make 200 ml of 10 mM dithiothreitol (DTT) 4x SSC solution by adding 309 mg of fresh DTT into 200 ml of 4x SSC buffer.</li>
	<li>Soak the gel with DTT-4x SSC buffer and cover. Gently rock for 20 min (10 rotations per minute). Rinse gel with DTT-free 4x SSC buffer.</li>
</ol>
5. Vacuum Blotter Assembly and Sample Transfer to a Nitrocellulose Membrane
<ol>
	<li>Prepare vacuum blotter for transfer.
	<ol>
		<li>Carefully cut nitrocellulose membrane at dimensions slightly wider than the gel (i.e., 10 x 15 cm).</li>
		<li>Wet porous mat with dH2O and place it smooth-side-up in the blotter.</li>
		<li>Wet nitrocellulose membrane with DTT-free 4x SSC buffer and place it at the center of the porous mat.</li>
		<li>Cover the porous mat with the rubber gasket, leaving the opening of the gasket precisely aligned with the nitrocellulose membrane. If porous mat is still visible, carefully adjust the membrane to ensure no gap remains between gasket and membrane.</li>
	</ol>
	</li>
	<li>Carefully place the agarose gel on top of the membrane. Ensure gel forms a tight seal with the gasket and the wells of the gel are positioned on the membrane for transfer.
	<ol>
		<li>Avoid the formation of bubbles between the membrane and the gel. To minimize the formation of bubbles, squirt few drops of 4x SSC buffer on the membrane and slide the gel from top to bottom to flush any formed bubbles. Avoid moving the gel on the membrane as proteins will begin to blot immediately.</li>
	</ol>
	</li>
	<li>Carefully cover the gel with 4x SSC buffer.</li>
	<li>Begin mucin transfer by suction.
	<ol>
		<li>Turn vacuum blotter ON and set pressure at 40 - 50 mBar. Add a few drops of 4x SSC buffer on the gel every 5 - 10 min to prevent the gel from drying out. Run transfer for 90 min. Optional: Upon completion, mark the wells with a pencil for orientation.</li>
	</ol>
	</li>
	<li>Dispose of the gel and retrieve nitrocellulose membrane using plastic tweezers on the edge of the membrane.</li>
</ol>
6. Membrane Blocking and Detection
<ol>
	<li>Rinse membrane immediately with 1x phosphate-buffered saline (PBS). Do not let the membrane dry out.</li>
	<li>Immerse the membrane into 50 ml of 3% milk-PBS blocking buffer and place on a rocker at room temperature for 1 hr. After incubation, discard the blocking buffer.</li>
	<li>Immerse membrane in 1% milk-PBS primary antibody solution. Incubate the membrane in the primary antibody solution overnight on a rocker at 4 &#176;C. After incubation, discard the primary antibody solution. Dilute the primary antibodies to a 1:2,000 ratio of antibody solution to blocking buffer. Note: For samples originating from mice, we use UNC 222 rabbit anti-Muc5b and goat anti-Green Fluorescent Protein (GFP). For samples originating from humans, we use H300 anti-MUC5B and 45M1 anti-MUC5AC primary antibodies.</li>
	<li>Wash membrane 3 times with PBS for 10 min on a rocker.</li>
	<li>Immerse membrane in 1% milk-PBS secondary antibody solution. Dilute the secondary antibodies to a 1:7,500 ratio of antibody solution to blocking buffer (e.g., 700 anti-rabbit and 680 anti-goat) and incubate at room temperature for 1 hr on a rocker. Protect from light by incubating in a non-transparent container. Discard the secondary antibody solution after 1 hr.</li>
	<li>Wash membrane 3 times with PBS for 5 min. Rinse membrane with dH2O to remove salt.</li>
	<li>Read the membrane on an infrared fluorescence system according to manufacturer&#39;s instructions.</li>
</ol>

<ol>
	<li>Henderson, A. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cystic+fibrosis+airway+secretions+exhibit+mucin+hyperconcentration+and+increased+osmotic+pressure.">Cystic fibrosis airway secretions exhibit mucin hyperconcentration and increased osmotic pressure.</a> J Clin Invest. 124 (7), 3047-3060 (2014).</li><li>Preciado, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MUC5B+Is+the+predominant+mucin+glycoprotein+in+chronic+otitis+media+fluid.">MUC5B Is the predominant mucin glycoprotein in chronic otitis media fluid.</a> Pediatr Res. 68 (3), 231-236 (2010).</li><li>Wang, Y. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IgG+in+cervicovaginal+mucus+traps+HSV+and+prevents+vaginal+herpes+infections.">IgG in cervicovaginal mucus traps HSV and prevents vaginal herpes infections.</a> Mucosal Immunol. 7 (5), 1036-1044 (2014).</li><li>Linden, S. K., Sutton, P., Karlsson, N. G., Korolik, V., McGuckin, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mucins+in+the+mucosal+barrier+to+infection.">Mucins in the mucosal barrier to infection.</a> Mucosal Immunol. 1 (3), 183-197 (2008).</li><li>Thornton, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mucus+glycoproteins+from+'normal'+human+tracheobronchial+secretion.">Mucus glycoproteins from 'normal' human tracheobronchial secretion.</a> Biochem J. 265 (1), 179-186 (1990).</li><li>Kesimer, M., Makhov, A. M., Griffith, J. D., Verdugo, P., Sheehan, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unpacking+a+gel-forming+mucin:+a+view+of+MUC5B+organization+after+granular+release.">Unpacking a gel-forming mucin: a view of MUC5B organization after granular release.</a> Am J Physiol Lung Cell Mol Physiol. 298 (1), L15-L22 (2010).</li><li>Kesimer, M., Sheehan, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mass+spectrometric+analysis+of+mucin+core+proteins.">Mass spectrometric analysis of mucin core proteins.</a> Methods Mol Biol. 842, 67-79 (2012).</li><li>van der Post, S., Thomsson, K. A., Hansson, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiple+enzyme+approach+for+the+characterization+of+glycan+modifications+on+the+C-terminus+of+the+intestinal+MUC2mucin.">Multiple enzyme approach for the characterization of glycan modifications on the C-terminus of the intestinal MUC2mucin.</a> J Proteome Res. 13 (12), 6013-6023 (2014).</li><li>Thornton, D. J., Carlstedt, I., Sheehan, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+glycoproteins+on+nitrocellulose+membranes+and+gels.">Identification of glycoproteins on nitrocellulose membranes and gels.</a> Methods Mol Biol. 32, 119-128 (1994).</li><li>Thornton, D. J., Carlstedt, I., Sheehan, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+glycoproteins+on+nitrocellulose+membranes+and+gels.">Identification of glycoproteins on nitrocellulose membranes and gels.</a> Mol Biotechnol. 5 (2), 171-176 (1996).</li><li>Sheehan, J. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physical+characterization+of+the+MUC5AC+mucin:+a+highly+oligomeric+glycoprotein+whether+isolated+from+cell+culture+or+in+vivo+from+respiratory+mucous+secretions.">Physical characterization of the MUC5AC mucin: a highly oligomeric glycoprotein whether isolated from cell culture or in vivo from respiratory mucous secretions.</a> Biochem J. 347 Pt 1, 37-44 (2000).</li><li>Thornton, D. J., Howard, M., Khan, N., Sheehan, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+two+glycoforms+of+the+MUC5B+mucin+in+human+respiratory+mucus.+Evidence+for+a+cysteine-rich+sequence+repeated+within+the+molecule.">Identification of two glycoforms of the MUC5B mucin in human respiratory mucus. Evidence for a cysteine-rich sequence repeated within the molecule.</a> J Biol Chem. 272 (14), 9561-9566 (1997).</li><li>Sheehan, J. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+molecular+intermediates+in+the+assembly+pathway+of+the+MUC5AC+mucin.">Identification of molecular intermediates in the assembly pathway of the MUC5AC mucin.</a> J Biol Chem. 279 (15), 15698-15705 (2004).</li><li>Ehre, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Overexpressing+mouse+model+demonstrates+the+protective+role+of+Muc5ac+in+the+lungs.">Overexpressing mouse model demonstrates the protective role of Muc5ac in the lungs.</a> Proc Natl Acad Sci U S A. 109 (41), 16528-16533 (2012).</li><li>Livraghi, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Airway+and+lung+pathology+due+to+mucosal+surface+dehydration+in+{beta}-epithelial+Na++channel-overexpressing+mice:+role+of+TNF-{alpha}+and+IL-4R{alpha}+signaling,+influence+of+neonatal+development,+and+limited+efficacy+of+glucocorticoid+treatment.">Airway and lung pathology due to mucosal surface dehydration in {beta}-epithelial Na+ channel-overexpressing mice: role of TNF-{alpha} and IL-4R{alpha} signaling, influence of neonatal development, and limited efficacy of glucocorticoid treatment.</a> J Immunol. 182 (7), 4357-4367 (2009).</li><li>Martino, M. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ER+stress+transducer+IRE1beta+is+required+for+airway+epithelial+mucin+production.">The ER stress transducer IRE1beta is required for airway epithelial mucin production.</a> Mucosal Immunol. 6 (3), 639-654 (2013).</li><li>Nguyen, L. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+exposure+to+beta-blockers+attenuates+inflammation+and+mucin+content+in+a+murine+asthma+model.">Chronic exposure to beta-blockers attenuates inflammation and mucin content in a murine asthma model.</a> Am J Respir Cell Mol Biol. 38 (3), 256-262 (2008).</li><li>Papakonstantinou, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=COPD+exacerbations+are+associated+with+pro-inflammatory+degradation+of+hyaluronic+acid.">COPD exacerbations are associated with pro-inflammatory degradation of hyaluronic acid.</a> Chest. , (2015).</li><li>Abdullah, L. H., Wolber, C., Kesimer, M., Sheehan, J. K., Davis, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studying+mucin+secretion+from+human+bronchial+epithelial+cell+primary+cultures.">Studying mucin secretion from human bronchial epithelial cell primary cultures.</a> Methods Mol Biol. 842, 259-277 (2012).</li></ol>

The authors have no conflict to disclose.

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...

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, e.g., cystic fibrosis1, chronic otitis media2 and cervicovaginal infection3. Therefore, it is important to understand the role of mucins in health and disease and to establish routine protocols for protein identification.
To date, 19 mucins genes have been identified and encode for large polypeptide chains ranging from 1,200 (e.g., MUC1) to 22,000 (e.g., MUC16) amino acids. The mucin gene family can be divided into two subtypes: the membrane-associated mucins, involved in cell signaling and surface shielding, and the gel-forming mucins, responsible for the viscoelastic properties of mucus gels. Membrane-associated mucins are mostly monomeric and attach to the cell surfaces via a hydrophobic membrane-spanning domain. In contrast, gel-forming mucins possess several von Willebrand factor (vWF)-like and cysteine-rich domains that are essential for the formation of dynamic polymeric networks. Large glycans are attached to serine and threonine residues distributed throughout the apomucin. These dense O-linked oligosaccharides can contribute up to 80% of the molecular weight4. Intra- and inter-molecular disulfide bonds connecting mucin monomers ensure the integrity of the mucin gel network. As a result of heavy glycosylation and multimerization, mucins are among the largest molecules in the animal world and cannot be analyzed by standard gel electrophoresis using conventional SDS-PAGE polyacrylamide gel and standard protein ladders. These methods resolve/separate proteins with molecular weights lower than 250 kDa while mucin monomers can reach up to 2 MDa in the case of MUC16. However, high-molecular-weight protein ladders can be used to study small mucin monomers (i.e., MUC1).
A variety of techniques can be applied to study mucin size, conformation and interaction. Traditionally, biochemical characterization of mucins is accomplished by mucin isolation via isopycnic density-gradient centrifugation in denaturing buffer, followed by size-exclusion chromatography and immunodetection (e.g., slot blotting)5. Dynamic and/or multi-angle light scattering provide information on the oligomeric state of mucin-rich samples1. In addition, rate-zonal centrifugation coupled with immunodetection and transmission electron microscopy are commonly used to determine the macromolecular conformation of mucins6. Mass spectrometry is also used to quantify mucins, detect proteolytic cleavage and analyze oligosaccharide composition1,7,8. Such techniques are costly, time consuming and often require large volumes and/or high concentrations of sample. The methodology described herein, i.e., mucin separation by electrophoresis, is reproducible, low cost and can be used in high-throughput studies to provide relative mucin quantitation and investigate polymer assembly. However, this assay requires high-affinity, high-specificity mucin antibodies that may not be available for rare mucins (e.g., MUC19) or certain species (e.g., pig, ferret).
Agarose Western blotting is suitable to resolve a wide variety of mucin-rich samples with concentrations ranging from 50 &#181;g/ml (e.g., cell washes) to 5 mg/ml (e.g., sputum). This assay was introduced in the 1990s and was only performed in few specialized laboratories9,10. Initially, this technique helped identify subpopulations of mucin monomers in human respiratory secretions11,12 and confirmed the oligomerization process in goblet cells, which consists of dimer formation in the endoplasmic reticulum followed by dimer multimerization in the Golgi apparatus13. More recently, the generation of polyclonal antibodies against murine mucins facilitated studies on small animal models (e.g., mucin deficient, &#946;ENaC, OVA-challenged mouse models) and opened a new field of research for preclinical studies testing pharmacological compounds aimed at removing mucus from the lungs14-17. As a result of an increasing interest in mucin biology and the generation of novel, more specific mucin antibodies, we describe herein the methodology to separate mucins by agarose gel electrophoresis, vacuum transfer to nitrocellulose and two-color infrared fluorescent detection.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Tris Base</td>
			<td>Sigma</td>
			<td>T6060-1kg</td>
			<td>1kg</td>
		</tr>
		<tr>
			<td>Glacial Acetic Acid</td>
			<td>Sigma</td>
			<td>ARK2183-1L</td>
			<td>1L</td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sigma</td>
			<td>EDS-100g</td>
			<td>100g</td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Fisher</td>
			<td>BP229-1</td>
			<td>1L</td>
		</tr>
		<tr>
			<td>Bromophenol Blue</td>
			<td>Sigma</td>
			<td>114391-5g</td>
			<td>5g</td>
		</tr>
		<tr>
			<td>SDS (Sodium Dodecyl Sulfate)</td>
			<td>Sigma</td>
			<td>L6026-50g</td>
			<td>50g</td>
		</tr>
		<tr>
			<td>20X SSC (Sodium Saline Citrate) Buffer</td>
			<td>Promega</td>
			<td>V4261</td>
			<td>1L</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Fisher</td>
			<td>S271-1</td>
			<td>1kg</td>
		</tr>
		<tr>
			<td>Trisodium Citrate (Na3C6H5O7)</td>
			<td>Sigma</td>
			<td>W302600-1kg</td>
			<td>1kg</td>
		</tr>
		<tr>
			<td>10 mM DTT (dithiothreitol)&#160;</td>
			<td>Sigma</td>
			<td>D0632</td>
			<td>25g</td>
		</tr>
		<tr>
			<td>Milk Powder</td>
			<td>Saco</td>
			<td></td>
			<td>Instant non-fat dry milk</td>
		</tr>
		<tr>
			<td>Dulbecco Phosphate Buffered Saline (D-PBS)</td>
			<td>Gibco lifetechnologies</td>
			<td>14200-025</td>
			<td>500mL</td>
		</tr>
		<tr>
			<td>Anti-GFP Goat Primary Antibody (mouse samples)</td>
			<td>Rockland antibodies and assays</td>
			<td>600-101-215</td>
			<td>1 mg</td>
		</tr>
		<tr>
			<td>UNC 222 Anti-Muc5b Rabbit Primary Antibody (mouse samples)</td>
			<td>UNC</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>H300 Anti-MUC5B Primary Antibodies (human samples)</td>
			<td>Santa Cruz</td>
			<td>sc-20119</td>
			<td>200ug</td>
		</tr>
		<tr>
			<td>45M1 Anti-MUC5AC Primary Antibodies (human samples)</td>
			<td>Abcam</td>
			<td>ab3649</td>
			<td>100ug</td>
		</tr>
		<tr>
			<td>Donkey Anti-rabbit 800CW IR Dye</td>
			<td>LI-COR Biosciences</td>
			<td>926-32213</td>
			<td>0.5mg</td>
		</tr>
		<tr>
			<td>Donkey Anti-mouse 680LT IR Dye</td>
			<td>LI-COR Biosciences</td>
			<td>926-68022</td>
			<td>0.5mg</td>
		</tr>
		<tr>
			<td>Electrophoresis Gel Box and Casting Tray</td>
			<td>Owl Seperation Systems</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Power Supply Box</td>
			<td>Biorad</td>
			<td>Model 200/20</td>
			<td></td>
		</tr>
		<tr>
			<td>Membrane Blotting Paper</td>
			<td>Amersham&#160;</td>
			<td>10600016&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Whatman Paper and Nitrocellulose membrane&#160;</td>
			<td>GE&#160;</td>
			<td>10 439 196</td>
			<td></td>
		</tr>
		<tr>
			<td>Boekel/Appligene Vacuum Blotter 230v</td>
			<td>Expotech USA</td>
			<td>230600-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Odyssey Infrared Fluorescence System</td>
			<td>LI-COR Biosciences</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

mucin agarose gel electrophoresis: western blotting for high-molecular-weight glycoproteins

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.

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...

Watch this Scientific Journal Video about Mucin Agarose Gel Electrophoresis: Western Blotting for High-molecular-weight Glycoproteins at JoVE.com

Mucin Agarose Gel Electrophoresis: Western Blotting for High-molecular-weight Glycoproteins

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 ...

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JoVE Journal

Biology

25.2K Views.  University of North Carolina at Chapel Hill. 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. 

Video: Mucin Agarose Gel Electrophoresis: Western Blotting for High-molecular-weight Glycoproteins

Denaturing Gradient Gel Electrophoresis (DGGE)

Denaturing Gradient Gel Electrophoresis DGGE

Okay.Hi, my name is Celeste Peterson and I'm a fellow at Harvard University studying microbial bio film communities. So I am profiling the bacterial communities by looking at their 60 N sequence and how this sequence changes over time in space. And to do that, I'm using DDGE.This is not a normal acry of my well, it needs to be kept at 60 degrees when it's run and the buffer needs to be pumped continuously. So we're gonna warm up the buffer for about an hour until it's at 60 degrees, and then we can run the towel. Now I'm gonna wash this plate with dilute uc solution, peeling around for impurities, andone, light that up.Anything like that can cause regularities. It is important to wipe off all the water. So when I assemble the gel, I'll put that chip on the outside of the gel.So the gel will be in between these two pieces of glass and the chip will be on the outside and it won't affect the gel in between. So now I'm gonna assemble the gel in these clamps and then I squeeze them together and tighten by turning to the right. As with any gel, it's important to make sure that the bottom is flush.To prevent making, we now turn the gel around and put it in here to get sealed with the gasket. So it's important when you do this that the gel, that the plates are actually lined up with the gasket here. So these knobs on the side then go in and you press down to type the seal.So this is a 30 mil syringe. And this part and this part come with the bio red kit and it just on like this. And that's just to get rid of the excess water in the tubes.So put the tubing onto the gel to load the gel. First you put an adapter into the tubing and then a needle look with that small adapter and put it right in the center of the gel just so it's fairly below the bottom glass. Then this wire adapter goes into the long tubing and it's going to connect to equal syringes containing the high and the low density solution.So these are pre-prepared solutions. The blue one, I've added a dye here that just indicates that this is the most denaturing solution and this is the least fitting train solution, the low density one. And they have everything in them.And now I'm gonna to make, gonna be Actually I twice as much the week. And once you've got the tempt, you have about five to seven minutes to fill the gel before the colon rises. And now we fill the syringe juice with the solution.So I'm gonna fill it with about 15 the solution. And then to get rid of any air bubbles, I'll turn it upside down and squeeze gently until that top air bubble is gone. Now this little screw here is gonna go into this groove.This adapter is gonna line up with this clamp here, and it's gonna get C clamped in very tightly. And then this tubing is gonna attach to the syringe. And the same thing is done on the other side with the high density matrix where it's time to deliver.And so I'm gonna be turning this wheel in a steady clockwise motion. And first the blue solution is gonna go out first because that's the the most in nature, and it's gonna form the bottom part of the gel. And then after a little while, the clear solution will start filling in the gel and the Gradient will be formed.One moment is the gently on an angle to And as soon as you finish pouring the gel to wash out your tubes immediately because they will polymerize Going, It's the group there. And then press down. So this little, And on the other side, I'll do the same thing.Okay.Hi, my name is Celeste Peterson and I'm a fellow at Harvard University studying microbial bio communities. So I am profiling the bacterial communities by looking at their 60 F sequence and how the sequence changes over time in space. And to do that, I'm using DDGE.So DGE is Dena gel electrophoresis. And basically the idea is that there's a gradient and the DNA, as it runs down the gradient gets de natured. And so different 16 species will stop at different points along the gradient.And so it ends up being a fingerprint of the different sexiness species in the community. So the goal of my experiment is to see who is in the community and how that's changing over time and space. And I can run the sexiness DDD gel and then I can cut out the bands and identify the species that are represented in each community.So one of the biggest issues when, when doing A DDG gel is to figure out the gradient that's the best. And so that is just something that needs to be played around with and figuring out for a particular community which type of gradient. So the one I'm using today is 35 to 55%urea.One of the big problems that can happen with this technique is that smears come up in in the leans. And I found for that, for whatever reason, one of the best things to do is to run the gels for a really long time and then the smears disappear. Well, today I'm just using it for general bacterial communities, but this can also be used for a specific family of bacteria to see how those change over time, and those tend to be very clean gels.You can also look at mutations in single genes with DDGE.

Western Blotting Using the Invitrogen NuPage Novex Bis Tris MiniGels

Western Blotting (or immunoblotting) is a standard laboratory procedure allowing investigators to verify the expression of a protein, determine the relative amount of the protein present in different samples, and analyze the results of co-immunoprecipitation experiments. In this method, a target protein is detected with a specific primary antibody in a given sample of tissue homogenate or extract. Protein separation according to molecular weight is achieved using denaturing SDS-PAGE. After transfer to a membrane, the target protein is probed with a specific primary antibody and detected by chemiluminescence.
Since its first description, the western-blotting technique has undergone several improvements, including pre-cast gels and user-friendly equipment. In our laboratory, we have chosen to use the commercially available NuPAGE electrophoresis system from Invitrogen. It is an innovative neutral pH, discontinuous SDS-PAGE, pre-cast mini-gel system. This system presents several advantages over the traditional Laemmli technique including: i) a longer shelf life of the pre-cast gels ranging from 8 months to 1 year; ii) a broad separation range of molecular weights from 1 to 400 kDa depending of the type of gel used; and iii) greater versatility (range of acrylamide percentage, the type of gel, and the ionic composition of the running buffer).
The procedure described in this video article utilizes the Bis-Tris discontinuous buffer system with 4-12% Bis-Tris gradient gels and MES running buffer, as an illustration of how to perform a western-blot using the Invitrogen NuPAGE electrophoresis system. In our laboratory, we have obtained good and reproducible results for various biochemical applications using this western-blotting method.

This technical article describes a standard western-blotting procedure using the commercially available NuPAGE electrophoresis Mini-Gel system from Invitrogen.

Western Blotting (or immunoblotting) is a standard laboratory procedure allowing investigators to verify the expression of a protein, determine the ...

Assessing Neural Stem Cell Motility Using an Agarose Gel-based Microfluidic Device

While microfluidic technology is reaching a new level of maturity for macromolecular assays, cell-based assays are still at an infant stage1. This is largely due to the difficulty with which one can create a cell-compatible and steady microenvironment using conventional microfabrication techniques and materials. We address this problem via the introduction of a novel microfabrication material, agarose gel, as the base material for the microfluidic device. Agarose gel is highly malleable, and permeable to gas and nutrients necessary for cell survival, and thus an ideal material for cell-based assays. We have shown previously that agarose gel based devices have been successful in studying bacterial and neutrophil cell migration2. In this report, three parallel microfluidic channels are patterned in an agarose gel membrane of about 1mm thickness. Constant flows with media/buffer are maintained in the two side channels using a peristaltic pump. Cells are maintained in the center channel for observation. Since the nutrients and chemicals in the side channels are constantly diffusing from the side to center channel, the chemical environment of the center channel is easily controlled via the flow along the side channels. Using this device, we demonstrate that the movement of neural stem cells can be monitored optically with ease under various chemical conditions, and the experimental results show that the over expression of epidermal growth factor receptors (EGFR) enhances the motility of neural stem cells. Motility of neural stem cells is an important biomarker for assessing cells aggressiveness, thus tumorigenic factor3. Deciphering the mechanism underlying NSC motility will yield insight into both disorders of neural development and into brain cancer stem cell invasion.

We demonstrate that the over expression of epidermal growth factor receptors (EGFR) enhances the motility of neural stem cells(NSCs) using a novel agarose gel based microfluidic device. This technology can be readily adaptable to other mammalian cell systems where cell sources are scarce, such as human neural stem cells, and the turn around time is critical.

While microfluidic technology is reaching a new level of maturity for macromolecular assays, cell-based assays are still at an infant stage1. This is ...

Screening for Amyloid Aggregation by Semi-Denaturing Detergent-Agarose Gel Electrophoresis

Amyloid aggregation is associated with numerous protein misfolding pathologies and underlies the infectious properties of prions, which are conformationally self-templating proteins that are thought to have beneficial roles in lower organisms.  Amyloids have been notoriously difficult to study due to their insolubility and structural heterogeneity.  However, resolution of amyloid polymers based on size and detergent insolubility has been made possible by Semi-Denaturing Detergent-Agarose Gel Electrophoresis (SDD-AGE).  This technique is finding widespread use for the detection and characterization of amyloid conformational variants.  Here, we demonstrate an adaptation of this technique that facilitates its use in large-scale applications, such as screens for novel prions and other amyloidogenic proteins.  The new SDD-AGE method uses capillary transfer for greater reliability and ease of use, and allows any sized gel to be accomodated.  Thus, a large number of samples, prepared from cells or purified proteins, can be processed simultaneously for the presence of SDS-insoluble conformers of tagged proteins.

SDD-AGE is a useful technique for the detection and characterization of amyloid-like polymers in cells. Here we demonstrate an adaptation that makes this technique amenable to large-scale applications.

Amyloid aggregation is associated with numerous protein misfolding pathologies and underlies the infectious properties of prions, which are ...

Denaturing Urea Polyacrylamide Gel Electrophoresis (Urea PAGE)

Urea PAGE or denaturing urea polyacrylamide gel electrophoresis employs 6-8 M urea, which denatures secondary DNA or RNA structures and is used for their separation in a polyacrylamide gel matrix based on the molecular weight. Fragments between 2 to 500 bases, with length differences as small as a single nucleotide, can be separated using this method1. The migration of the sample is dependent on the chosen acrylamide concentration. A higher percentage of polyacrylamide resolves lower molecular weight fragments. The combination of urea and temperatures of 45-55 &deg;C during the gel run allows for the separation of unstructured DNA or RNA molecules.
In general this method is required to analyze or purify single stranded DNA or RNA fragments, such as synthesized or labeled oligonucleotides or products from enzymatic cleavage reactions.
In this video article we show how to prepare and run the denaturing urea polyacrylamide gels. Technical tips are included, in addition to the original protocol 1,2.

Denaturing Urea Polyacrylamide Gel Electrophoresis Urea PAGE

Denaturing urea polyacrylamide gel electrophoresis is used to separate single-stranded DNA or RNA up to a limit of 500 nucleotides. Urea in combination with heat denatures samples and unstructured single strands migrate within the gel matrix according to their molecular weight.

Urea PAGE or denaturing urea polyacrylamide gel electrophoresis employs 6-8 M urea, which denatures secondary DNA or RNA structures and is used for their ...

Extraction of High Molecular Weight Genomic DNA from Soils and Sediments

The soil microbiome is a vast and relatively unexplored reservoir of genomic diversity and metabolic innovation that is intimately associated with nutrient and energy flow within terrestrial ecosystems. Cultivation-independent environmental genomic, also known as metagenomic, approaches promise unprecedented access to this genetic information with respect to pathway reconstruction and functional screening for high value therapeutic and biomass conversion processes. However, the soil microbiome still remains a challenge largely due to the difficulty in obtaining high molecular weight DNA of sufficient quality for large insert library production. Here we introduce a protocol for extracting high molecular weight, microbial community genomic DNA from soils and sediments. The quality of isolated genomic DNA is ideal for constructing large insert environmental genomic libraries for downstream sequencing and screening applications. 
The procedure starts with cell lysis. Cell walls and membranes of microbes are lysed by both mechanical (grinding) and chemical forces (&beta;-mercaptoethanol). Genomic DNA is then isolated using extraction buffer, chloroform-isoamyl alcohol and isopropyl alcohol. The buffers employed for the lysis and extraction steps include guanidine isothiocyanate and hexadecyltrimethylammonium bromide (CTAB) to preserve the integrity of the high molecular weight genomic DNA. Depending on your downstream application, the isolated genomic DNA can be further purified using cesium chloride (CsCl) gradient ultracentrifugation, which reduces impurities including humic acids. The first procedure, extraction, takes approximately 8 hours, excluding DNA quantification step. The CsCl gradient ultracentrifugation, is a two days process. During the entire procedure, genomic DNA should be treated gently to prevent shearing, avoid severe vortexing, and repetitive harsh pipetting.

A methodology to isolate high molecular weight and high quality genomic DNA from soil microbial community is described.

The soil microbiome is a vast and relatively unexplored reservoir of genomic diversity and metabolic innovation that is intimately associated with ...

Blue Native Polyacrylamide Gel Electrophoresis (BN-PAGE) for Analysis of Multiprotein Complexes from Cellular Lysates

Multiprotein complexes (MPCs) play a crucial role in cell signalling, since most proteins can be found in functional or regulatory complexes with other proteins (Sali, Glaeser et al. 2003). Thus, the study of protein-protein interaction networks requires the detailed characterization of MPCs to gain an integrative understanding of protein function and regulation. For identification and analysis, MPCs must be separated under native conditions. In this video, we describe the analysis of MPCs by blue native polyacrylamide gel electrophoresis (BN-PAGE). BN-PAGE is a technique that allows separation of MPCs in a native conformation with a higher resolution than offered by gel filtration or sucrose density ultracentrifugation, and is therefore useful to determine MPC size, composition, and relative abundance (Sch&auml;gger and von Jagow 1991); (Sch&auml;gger, Cramer et al. 1994). By this method, proteins are separated according to their hydrodynamic size and shape in a polyacrylamide matrix. Here, we demonstrate the analysis of MPCs of total cellular lysates, pointing out that lysate dialysis is the crucial step to make BN-PAGE applicable to these biological samples. Using a combination of first dimension BN- and second dimension SDS-PAGE, we show that MPCs separated by BN-PAGE can be further subdivided into their individual constituents by SDS-PAGE. Visualization of the MPC components upon gel separation is performed by standard immunoblotting. As an example for MPC analysis by BN-PAGE, we chose the well-characterized eukaryotic 19S, 20S, and 26S proteasomes.

Blue Native Polyacrylamide Gel Electrophoresis BN-PAGE for Analysis of Multiprotein Complexes from Cellular Lysates

In this video, we describe the characterization of multiprotein complexes (MPCs) by blue native polyacrylamide gel electrophoresis (BN-PAGE). In a first dimension, dialyzed cellular lysates are separated by BN-PAGE to identify individual MPCs. In a second dimension SDS-PAGE, MPCs of interest are further subdivided to analyze their constituents by immunoblotting.

Multiprotein complexes (MPCs) play a crucial role in cell signalling, since most proteins can be found in functional or regulatory complexes with other ...

Visualization of UV-induced Replication Intermediates in E. coli using Two-dimensional Agarose-gel Analysis

Inaccurate replication in the presence of DNA damage is responsible for the majority of cellular rearrangements and mutagenesis observed in all cell types and is widely believed to be directly associated with the development of cancer in humans. DNA damage, such as that induced by UV irradiation, severely impairs the ability of replication to duplicate the genomic template accurately. A number of gene products have been identified that are required when replication encounters DNA lesions in the template. However, a remaining challenge has been to determine how these proteins process lesions during replication in vivo. Using Escherichia coli as a model system, we describe a procedure in which two-dimensional agarose-gel analysis can be used to identify the structural intermediates that arise on replicating plasmids in vivo following UV-induced DNA damage. This procedure has been used to demonstrate that replication forks blocked by UV-induced damage undergo a transient reversal that is stabilized by RecA and several gene products associated with the RecF pathway. The technique demonstrates that these replication intermediates are maintained until a time that correlates with the removal of the lesions by nucleotide excision repair and replication resumes.

Visualization of UV-induced Replication Intermediates in E. coli using Two-dimensional Agarose-gel Analysis

We present a procedure by which two-dimensional agarose-gel analysis can be used to identify the structure of replication intermediates that occur following UV irradiation.

Inaccurate replication in the presence of DNA damage is responsible for the majority of cellular rearrangements and mutagenesis observed in all cell types ...

Western Blotting: Sample Preparation to Detection

Western blotting is an analytical technique used to detect specific proteins in a given sample of tissue homogenate or extract. It uses gel electrophoresis to separate native or denatured proteins by the length of the polypeptide (denaturing conditions) or by the 3-D structure of the protein (native/ non-denaturing conditions). The proteins are then transferred to a membrane (typically nitrocellulose or PVDF), where they are probed (detected) using antibodies specific to the target protein.

Western blotting is an analytical technique used to detect specific proteins in a given sample of tissue homogenate or extract.

Western blotting is an analytical technique used to detect specific proteins in a given sample of tissue homogenate or extract. It uses gel ...

Extraction of High Molecular Weight DNA from Microbial Mats

Successful and accurate analysis and interpretation of metagenomic data is dependent upon the efficient extraction of high-quality, high molecular weight (HMW) community DNA. However, environmental mat samples often pose difficulties to obtaining large concentrations of high-quality, HMW DNA. Hypersaline microbial mats contain high amounts of extracellular polymeric substances (EPS)1 and salts that may inhibit downstream applications of extracted DNA. Direct and harsh methods are often used in DNA extraction from refractory samples. These methods are typically used because the EPS in mats, an adhesive matrix, binds DNA2,3 during direct lysis. As a result of harsher extraction methods, DNA becomes fragmented into small sizes4,5,6.
The DNA thus becomes inappropriate for large-insert vector cloning. In order to circumvent these limitations, we report an improved methodology to extract HMW DNA of good quality and quantity from hypersaline microbial mats. We employed an indirect method involving the separation of microbial cells from the background mat matrix through blending and differential centrifugation. A combination of mechanical and chemical procedures was used to extract and purify DNA from the extracted microbial cells. Our protocol yields approximately 2 &mu;g of HMW DNA (35-50 kb) per gram of mat sample, with an A260/280 ratio of 1.6. Furthermore, amplification of 16S rRNA genes7 suggests that the protocol is able to minimize or eliminate any inhibitory effects of contaminants. Our results provide an appropriate methodology for the extraction of HMW DNA from microbial mats for functional metagenomic studies and may be applicable to other environmental samples from which DNA extraction is challenging.

We provide an improved protocol for extracting high molecular weight DNA from hypersaline microbial mats. Microbial cells are separated from the mat matrix prior to DNA extraction and purification. This enhances the concentrations, quality, and size of the DNA. The protocol may be used for other refractory samples.

Successful and accurate analysis and interpretation of metagenomic data is dependent upon the efficient extraction  of high-quality, high molecular weight ...