We thank Laura Vanderploeg for preparing figures. Work in the Sheets lab is supported by NSF grant 1050395 and NIH grant (R21HD076828). Work in the Ryder lab is supported by NIH grants R01GM117237 and R01GM117008. Megan Dowdle is supported by a SciMed GRS Advanced Opportunity Fellowship through University of Wisconsin-Madison Graduate School and Biotechnology Training Program through the National Institute of General Medical Sciences of the National Institutes of Health (T32GM008349).

1. Preparation of the Horizontal Native Polyacrylamide Gel4.
<ol>
	<li>Preparation of the materials needed.
	<ol>
		<li>For the horizontal gel apparatus, use a gel box (37 cm x 24 cm) with a 27 cm x 21 cm tray and a capacity for two 24-well combs. This setup provides a total of 48 samples that can be analyzed simultaneously.</li>
		<li>Prepare the following reagents: 40% Acrylamide-Bis 19:1, 5x TBE (Tris-Borate-EDTA pH 8.0), TEMED, and 10% APS (ammonium persulfate).</li>
	</ol>
...

<ol>
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G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrophoretic+mobility+shift+assay+(EMSA)+for+detecting+protein-nucleic+acid+interactions.">Electrophoretic mobility shift assay (EMSA) for detecting protein-nucleic acid interactions.</a> Nat Protoc. 2 (8), 1849-1861 (2007).</li><li>Pagano, J. M., Farley, B. M., Essien, K. I., Ryder, S. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+recognition+by+the+embryonic+cell+fate+determinant+and+germline+totipotency+factor+MEX-3.">RNA recognition by the embryonic cell fate determinant and germline totipotency factor MEX-3.</a> Proc Natl Acad Sci USA. 106 (48), 20252-20257 (2009).</li><li>Royer, C. A., Scarlata, S. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence+approaches+to+quantifying+biomolecular+interactions.">Fluorescence approaches to quantifying biomolecular interactions.</a> Meth Enzymol. 450, 79-106 (2008).</li><li>Su, C., Wang, F., Ciolek, D., Pan, Y. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrophoresis+of+proteins+and+protein-protein+complexes+in+native+polyacrylamide+gels+using+a+horizontal+gel+apparatus.">Electrophoresis of proteins and protein-protein complexes in native polyacrylamide gels using a horizontal gel apparatus.</a> Anal Biochem. 223, 93-98 (1994).</li><li>Buczek, P., Horvath, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermodynamic+Characterization+of+Binding+Oxytricha+nova+Single+Strand+Telomere+DNA+with+the+Alpha+Protein+N-terminal+Domain.">Thermodynamic Characterization of Binding Oxytricha nova Single Strand Telomere DNA with the Alpha Protein N-terminal Domain.</a> J Mol Biol. 359 (5), 1217-1234 (2006).</li><li>Zhang, Y., Park, S., Blaser, S., Sheets, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determinants+of+RNA+binding+and+translational+repression+by+the+Bicaudal-C+regulatory+protein.">Determinants of RNA binding and translational repression by the Bicaudal-C regulatory protein.</a> J Biol Chem. 289 (11), 7497-7504 (2014).</li><li>Gamberi, C., Lasko, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Bic-C+family+of+developmental+translational+regulators.">The Bic-C family of developmental translational regulators.</a> Comp Funct Genomics. , 141386 (2012).</li><li>Saffman, E. 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=Premature+translation+of+oskar+in+oocytes+lacking+the+RNA-binding+protein+bicaudal-C.">Premature translation of oskar in oocytes lacking the RNA-binding protein bicaudal-C.</a> Mol Cell Biol. 18 (8), 4855-4862 (1998).</li><li>Chicoine, 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=Bicaudal-C+recruits+CCR4-NOT+deadenylase+to+target+mRNAs+and+regulates+oogenesis,+cytoskeletal+organization,+and+its+own+expression.">Bicaudal-C recruits CCR4-NOT deadenylase to target mRNAs and regulates oogenesis, cytoskeletal organization, and its own expression.</a> Dev Cell. 13 (5), 691-704 (2007).</li><li>Zhang, 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=Bicaudal-C+spatially+controls+translation+of+vertebrate+maternal+mRNAs.">Bicaudal-C spatially controls translation of vertebrate maternal mRNAs.</a> RNA. 19 (11), 1575-1582 (2013).</li><li>Maisonneuve, 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=Bicaudal+C,+a+novel+regulator+of+Dvl+signaling+abutting+RNA-processing+bodies,+controls+cilia+orientation+and+leftward+flow.">Bicaudal C, a novel regulator of Dvl signaling abutting RNA-processing bodies, controls cilia orientation and leftward flow.</a> Development. 136 (17), 3019-3030 (2009).</li><li>Tran, U., 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+RNA-binding+protein+bicaudal+C+regulates+polycystin+2+in+the+kidney+by+antagonizing+miR-17+activity.">The RNA-binding protein bicaudal C regulates polycystin 2 in the kidney by antagonizing miR-17 activity.</a> Development. 137 (7), 1107-1116 (2010).</li><li>Pagano, J. M., Clingman, C. C., Ryder, S. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+approaches+to+monitor+protein-nucleic+acid+interactions+using+fluorescent+probes.">Quantitative approaches to monitor protein-nucleic acid interactions using fluorescent probes.</a> RNA. 17 (1), 14-20 (2011).</li><li>Foley, T. L., 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=Platform+to+Enable+the+Pharmacological+Profiling+of+Small+Molecules+in+Gel-Based+Electrophoretic+Mobility+Shift+Assays.">Platform to Enable the Pharmacological Profiling of Small Molecules in Gel-Based Electrophoretic Mobility Shift Assays.</a> J Biomol Screen. 21 (10), 1125-1131 (2016).</li></ol>

The authors have nothing to disclose.

Native polyacrylamide gels are an invaluable tool for investigating protein-RNA interactions and traditionally these gels are electrophoresed vertically2,3. We have used a modification of the protocol that substitutes native polyacrylamide gels created and electrophoresed horizontally1,4,6,7,15. These ...

Electrophoretic mobility shift assays (EMSAs) have proven to be an invaluable biochemical tool to analyze specific protein-nucleic acid interactions1,2,3. These assays can provide important information regarding the binding affinity of proteins to RNA or DNA3, the component stoichiometry of nucleic acid-protein complexes1 and provide important new insights about the binding specificity of RNA binding proteins via substrate competition experiments1.
The traditional experimental setup for these assays consists of mixing purified protein with a radiolabeled RNA substrate. The resulting complexes are then analyzed with non-denaturing (native) polyacrylamide gels poured between two glass plates followed by sample electrophoresis in a vertical apparatus3. While this approach has been used exhaustively to provide important insights in the biochemical mechanisms that underlie the binding of proteins to nucleic acids, it also has several limitations. For example, this basic strategy has relatively low throughput and it is not readily adaptable for applications that require analyzing many binding reactions in parallel. In addition, with the traditional vertical apparatus it is challenging to potentially monitor complexes at multiple times during electrophoresis3,4.
Here we present an adaptation of the EMSA assay that uses native polyacrylamide gels cast in a flatbed apparatus, horizontal electrophoresis and fluorescently labeled RNA substrates4,5,6,7. The incorporation of these relatively simple modifications to the basic strategy provides some powerful advantages. In particular, the horizontal flatbed format easily lends itself to analyzing dozens of samples simultaneously4. Also, for some RNA-protein complexes, such as those formed between the Bicaudal-C protein and its RNA substrate electrophoresis in a horizontal gel provides an increased ability to resolve distinct RNA-protein complexes and discriminate these from unbound RNA substrate.

<table border="0" cellpadding="0" cellspacing="0" width="1432">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:373px;">Horizontal Gel Box</td>
			<td style="width:112px;">OWL</td>
			<td style="width:116px;">N/A</td>
			<td style="width:831px;">Product no longer made. Similar gel boxes can be found at Thermo Scientific, A-series gel boxes. Catalog Number: A2-BP</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">24-well large large horizontal gel electrophoresis combs</td>
			<td>OWL</td>
			<td>N/A</td>
			<td>Product no longer made. Similar gel boxes can be found at Thermo Scientific, A-series gel box combs. Catalog Number: A2-24C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Powerpac 300</td>
			<td>Bio-Rad</td>
			<td>1655050</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mini-Protean II Electrophoresis Cell</td>
			<td>Bio-Rad</td>
			<td>165-2940</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">InstaPAGE-19 40% 19:1 Acrylamide/Bis</td>
			<td>IBI</td>
			<td>IB70015</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TEMED</td>
			<td>IBI</td>
			<td>IB70120</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">APS</td>
			<td>IBI</td>
			<td>IB70080</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Yeast tRNAs</td>
			<td>Ambion</td>
			<td>AM7119</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fluorescein labeled RNA</td>
			<td>IDT</td>
			<td>N/A</td>
			<td>Order can be made custom to length and desired sequence</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EDTA tetrasodium salt hydrate</td>
			<td>Sigma-Aldrich</td>
			<td>E5391-1KG</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HEPES</td>
			<td>Sigma-Aldrich</td>
			<td>H4034-500G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tris Base Ultrapure</td>
			<td>US Biological</td>
			<td>T8600</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Boric Acid</td>
			<td>Fisher Scientific</td>
			<td>BP168-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Potassium Chloride</td>
			<td>Fisher Scientific</td>
			<td>BP366-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tween-20</td>
			<td>Fisher Scientific</td>
			<td>BP337-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DEPC</td>
			<td>Sigma-Aldrich</td>
			<td>1609-47-8</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dithiothreitol (DTT)</td>
			<td>Sigma-Aldrich</td>
			<td>3483 12 3</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bovine Serum Albumin (BSA)</td>
			<td>Sigma-Aldrich</td>
			<td>9048-46-8</td>
			<td></td>
		</tr>
	</tbody>
</table>

horizontal gel electrophoresis for enhanced detection of protein-rna complexes

Native polyacrylamide gel electrophoresis is a fundamental tool of molecular biology that has been used extensively for the biochemical analysis of RNA-protein interactions. These interactions have been traditionally analyzed with polyacrylamide gels generated between two glass plates and samples electrophoresed vertically. However, polyacrylamide gels cast in trays and electrophoresed horizontally offers several advantages. For example, horizontal gels used to analyze complexes between fluorescent RNA substrates and specific proteins can be imaged multiple times as electrophoresis progresses. This provides the unique opportunity to monitor RNA-protein complexes at several points during the experiment. In addition, horizontal gel electrophoresis makes it possible to analyze many samples in parallel. This can greatly facilitate time course experiments as well as analyzing multiple reactions simultaneously to compare different components and conditions. Here we provide a detailed protocol for generating and using horizontal native gel electrophoresis for analyzing RNA-Protein interactions.

To demonstrate the power and versatility of the horizontal native gel electrophoresis we analyzed the binding of the Xenopus Bicaudal-C (Bicc1) protein to a fluorescently labeled RNA containing a Bicc1 binding site. Bicc1 proteins function as mRNA-specific translational repressors to control cell fate decisions during the maternal stages of animal development9,10,11,<sup class...

Watch this Scientific Journal Video about Horizontal Gel Electrophoresis for Enhanced Detection of Protein-RNA Complexes at JoVE.com

Horizontal Gel Electrophoresis for Enhanced Detection of Protein-RNA Complexes

Native polyacrylamide gel electrophoresis is a fundamental tool for analyzing RNA-protein interactions. Traditionally most experiments have used vertical gels. However, horizontal gels provide several advantages, such as the opportunity to monitor complexes during electrophoresis. We provide a detailed protocol for generating and using horizontal native gel electrophoresis.

Native polyacrylamide gel electrophoresis is a fundamental tool of molecular biology that has been used extensively for the biochemical analysis of ...

The overall of this protocol is to analyze RNA protein interactions using horizontal native gel electrophoresis. This method can help answer key questions in RNA biochemistry, such as defining the characteristics of specific RNA protein interactions. The main advantage of this technique is that it allows complex formation to be monitored multiple times during electrophoresis.For the horizontal gel apparatus, use a gel box with a 27 centimeter by 21 centimeter casting tray and a capacity for two 24 well combs. This set up provides a total of 48 samples that can be analyzed simultaneously. Prepare two liters of 1x TBE running buffer by diluting 400 milliliters of 5x TBE with 1, 600 milliliters of water and mixing.Place the TBE buffer in the cold room to cool. Prepare the following reagents following standard procedures, 40%acrylamide best 19:1, 5x TBE, temed and 10%ammonium per sulfate. To make a 10%native acrylamide gel, add the following to a 500 milliliter flask:80 milliliters of 5x TBE, 100 milliliters of 40%acrylamide and water to a final volume of 400 milliliters.Add four milliliters of 10%ammonium per sulfate and 400 microliters of temed and mix well. Pour the mix into the horizontal casting tray and allow the gel to polymerize in the fume hood for 30 minutes. The polymerized gel will be approximately two centimeters thick and a thin layer of liquid will remain on top of the gel.Place the gel into the gel box and take it into the cold room. Next, pour the liquid off and rinse with running buffer. Remove the combs carefully, add two liters of cold running buffer to the gel box and then use a syringe to rinse the wells with running buffer.Pre-run the gel at 120 volts for one hour at four degrees celsius in a cold room. While the gel is being prerun, prepare the binding reactions. Add the following binding reaction components to each RNA free microcentrifuge tube in this order:five microliters of 10 millimolar BSA, five microliters of 20 millimolar DTT, five microliters of 10 millimolar yeast tRNAs, 10 microliters of 5x binding buffer, bicaudal-c protein to a final concentration of 250 nanomolar in 50 microliters, DEPC-treated water to a final volume of 45 microliters and five microliters of fluorescently labeled RNA substrate.Close the tubes and flick gently to mix, centrifuge the tubes briefly and incubate in the dark for 30 minutes at room temperature. When the binding reactions are complete, add 15 microliters of 50%glycerol to each reaction and mix gently. Carefully load 30 microliters of each reaction into the wells of the gel, the amount of sample that can be loaded into a single well varies depending on the thickness of the gel and the size of the wells.The power supply to the gel apparatus, switch on the power, adjust the voltage to 120 volts and run the gel in four degree celsius. To prevent damaging or bleaching of the fluorescently labeled RNA, conduct electrophoresis in the dark. Electrophoresis times will vary depending upon the specifics of the RNA protein complex being analyzed.A major advantage of the horizontal electrophorated mobility shift assay analysis, is that electrophoresis can be stopped in the gel image prior to completion of the run. Perform analysis with any instrument designed for detecting an imaging fluorescent substrates. Adjust the imager settings, for fluorescently labeled ligands, use the following settings.Fluorescein wavelength of 473 nanometers, photomultiplier voltage of 750 volts and pixel size of 100 micrometers. Scan the gel to capture the image. After imaging, the gel can be placed back into the apparatus and electrophoresis can be continued for longer times.The binding of the xenopus bicaudal-C or Bicc1 protein to a fluorescently labeled Cripto1 mRNA containing a Bicc1 binding site, was analyzed by both vertical and horizontal native gel electrophoresis, as a negative control, Bicc1 was mixed with a fluorescently labeled RNA derived from CyclinB1 mRNA. It was readily apparent using either method, that Bicc1 binds to the Cripto1 RNA and forms a specific complex. However, the Bicc1, Cripto1 complexes were significantly more distinct when analyzed with the horizontal gel, facilitating their detection and allowing the discrimination of protein RNA complexes from unbound RNA.After imaging, the gel was returned to the gel apparatus, electrophoresis for an additional three and a half hours, and reimaged. As shown here, the complexes had migrated further and were still readily detectable, indicating their stability. Once mastered, this technique can be done in four to five hours, if it is performed properly.After watching this video, you should have a good understanding of how to analyze RNA protein interactions using horizontal native gel electrophoresis.

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Research

JoVE Journal

Biochemistry

11.8K Views.  University of Wisconsin School of Medicine and Public Health. The overall of this protocol is to analyze RNA protein interactions using horizontal native gel electrophoresis. This method can help answer key questions in RNA biochemistry, such as defining the characteristics of specific RNA protein interactions. The main advantage of this technique is that it allows complex formation to be monitored multiple times during electrophoresis.For the horizontal gel apparatus, use a gel box with a 27 centimeter by 21 centimeter casting tray and a capacit...