Name: using a gfp-tagged tmem184a construct for confirmation of heparin receptor identity
Uploaded: 2017-02-17T13:00:00
Description: Watch this Scientific Journal Video about Using a GFP-tagged TMEM184A Construct for Confirmation of Heparin Receptor Identity at JoVE.com

Research in the Lowe-Krentz lab is supported by research grant HL54269 from the National Institutes of Health to LLK.

1. Design of a GFP-protein Construct
<ol>
	<li>Purchase, or design and build, a GFP-tagged construct based on the protein in question. 
	NOTE: For a purchased construct, standard vectors are available from commercial laboratories that include some or all of the following suggestions: For a membrane protein, select a C-terminal location of the GFP because it is less likely to interfere with membrane protein trafficking. Consider an extension between the gene of interest and the GFP if there is reason to believe the...

<ol>
	<li>Pugh, R. 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=Transmembrane+Protein+184A+Is+a+Receptor+Required+for+Vascular+Smooth+Muscle+Cell+Responses+to+Heparin.">Transmembrane Protein 184A Is a Receptor Required for Vascular Smooth Muscle Cell Responses to Heparin.</a> J Biol Chem. 291, 5326-5341 (2016).</li><li>Daher, W., 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+Toxoplasma+TgPH1,+a+pleckstrin+homology+domain-containing+protein+that+binds+to+the+phosphoinositide+PI(3,5)P.">Identification of Toxoplasma TgPH1, a pleckstrin homology domain-containing protein that binds to the phosphoinositide PI(3,5)P.</a> Mol Biochem Parasitol. , (2016).</li><li>Vit, O., 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=Large-scale+identification+of+membrane+proteins+based+on+analysis+of+trypsin-protected+transmembrane+segments.">Large-scale identification of membrane proteins based on analysis of trypsin-protected transmembrane segments.</a> J Proteomics. , (2016).</li><li>Attwood, M. M., 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=Topology+based+identification+and+comprehensive+classification+of+four-transmembrane+helix+containing+proteins+(4TMs)+in+the+human+genome.">Topology based identification and comprehensive classification of four-transmembrane helix containing proteins (4TMs) in the human genome.</a> BMC genomics. 17, 268 (2016).</li><li>Zou, Z., 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=Genome-Wide+Identification+of+Jatropha+curcas+Aquaporin+Genes+and+the+Comparative+Analysis+Provides+Insights+into+the+Gene+Family+Expansion+and+Evolution+in+Hevea+brasiliensis.">Genome-Wide Identification of Jatropha curcas Aquaporin Genes and the Comparative Analysis Provides Insights into the Gene Family Expansion and Evolution in Hevea brasiliensis.</a> Front Plant Sci. 7, 395 (2016).</li><li>Gilotti, A. 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=Heparin+responses+in+vascular+smooth+muscle+cells+involve+cGMP-dependent+protein+kinase+(PKG).">Heparin responses in vascular smooth muscle cells involve cGMP-dependent protein kinase (PKG).</a> J Cell Physiol. 229, 2142-2152 (2014).</li><li>Farwell, S. 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=Heparin+Decreases+in+Tumor+Necrosis+Factor+alpha+(TNFalpha)-induced+Endothelial+Stress+Responses+Require+Transmembrane+Protein+184A+and+Induction+of+Dual+Specificity+Phosphatase+1.">Heparin Decreases in Tumor Necrosis Factor alpha (TNFalpha)-induced Endothelial Stress Responses Require Transmembrane Protein 184A and Induction of Dual Specificity Phosphatase 1.</a> J Biol Chem. 291, 5342-5354 (2016).</li><li>Xu, D., Esko, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Demystifying+heparan+sulfate-protein+interactions.">Demystifying heparan sulfate-protein interactions.</a> Annu Rev Biochem. 83, 129-157 (2014).</li><li>Chiodelli, P., Bugatti, A., Urbinati, C., Rusnati, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heparin/Heparan+sulfate+proteoglycans+glycomic+interactome+in+angiogenesis:+biological+implications+and+therapeutical+use.">Heparin/Heparan sulfate proteoglycans glycomic interactome in angiogenesis: biological implications and therapeutical use.</a> Molecules. 20, 6342-6388 (2015).</li><li>Slee, J. B., Lowe-Krentz, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Actin+realignment+and+cofilin+regulation+are+essential+for+barrier+integrity+during+shear+stress.">Actin realignment and cofilin regulation are essential for barrier integrity during shear stress.</a> J Cell Biochem. 114, 782-795 (2013).</li><li>Patton, W. 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=Identification+of+a+heparin-binding+protein+using+monoclonal+antibodies+that+block+heparin+binding+to+porcine+aortic+endothelial+cells.">Identification of a heparin-binding protein using monoclonal antibodies that block heparin binding to porcine aortic endothelial cells.</a> The Biochemical journal. 311, 461-469 (1995).</li><li>Doggett, T. M., Breslin, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+of+the+actin+cytoskeleton+in+live+endothelial+cells+expressing+GFP-actin.">Study of the actin cytoskeleton in live endothelial cells expressing GFP-actin.</a> J Vis Exp. , (2011).</li><li>Skalamera, 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=Generation+of+a+genome+scale+lentiviral+vector+library+for+EF1alpha+promoter-driven+expression+of+human+ORFs+and+identification+of+human+genes+affecting+viral+titer.">Generation of a genome scale lentiviral vector library for EF1alpha promoter-driven expression of human ORFs and identification of human genes affecting viral titer.</a> PloS one. 7, 51733 (2012).</li><li>Castro, M., Nikolaev, V. O., Palm, D., Lohse, M. J., Vilardaga, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Turn-on+switch+in+parathyroid+hormone+receptor+by+a+two-step+parathyroid+hormone+binding+mechanism.">Turn-on switch in parathyroid hormone receptor by a two-step parathyroid hormone binding mechanism.</a> Proc Natl Acad Sci U S A. 102, 16084-16089 (2005).</li><li>Albertazzi, L., Arosio, D., Marchetti, L., Ricci, F., Beltram, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+FRET+analysis+with+the+EGFP-mCherry+fluorescent+protein+pair.">Quantitative FRET analysis with the EGFP-mCherry fluorescent protein pair.</a> Photochem Photobiol. 85, 287-297 (2009).</li><li>Wang, S., 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=Domain+organization+of+the+ATP-sensitive+potassium+channel+complex+examined+by+fluorescence+resonance+energy+transfer.">Domain organization of the ATP-sensitive potassium channel complex examined by fluorescence resonance energy transfer.</a> J Biol Chem. 288, 4378-4388 (2013).</li><li>Christiansen, E., Hudson, B. D., Hansen, A. H., Milligan, G., Ulven, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+Characterization+of+a+Potent+Free+Fatty+Acid+Receptor+1+(FFA1)+Fluorescent+Tracer.">Development and Characterization of a Potent Free Fatty Acid Receptor 1 (FFA1) Fluorescent Tracer.</a> J Med Chem. 59, 4849-4858 (2016).</li><li>Chiang, C. F., Okou, D. T., Griffin, T. B., Verret, C. R., Green Williams, M. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=fluorescent+protein+rendered+susceptible+to+proteolysis:+positions+for+protease-sensitive+insertions.">fluorescent protein rendered susceptible to proteolysis: positions for protease-sensitive insertions.</a> Arch Biochem Biophys. 394, 229-235 (2001).</li></ol>

The protocols reported here were designed to provide confirmatory evidence for the identification of TMEM184A as a heparin receptor in vascular cells1. Knockdown techniques are routinely used as one mechanism to confirm the identification of novel proteins. However, some functional loss after knockdown is typically not sufficient proof that a candidate protein is actually the correct receptor (or other functional protein). It is also important to have evidence that the candidate protein actually e...

Identification of candidate proteins for novel functions often depends upon affinity-based isolation protocols followed by partial sequence determination. Recent examples of newly identified proteins include transmembrane protein 184A (TMEM184A), a heparin receptor identified after heparin affinity interactions1, and TgPH1, a pleckstrin homology domain protein that binds phosphoinositide PI(3,5)P22. Other novel protein identification involves direct sequence analysis of peptides such as that by Vit, et al. who used transmembrane peptides to identify protein products from previously uncharacterized genes3. Similarly, identification of novel protein sequences can be accomplished using bioinformatics searching of previously characterized protein families such as identification of new 4TM proteins4. Examination of aquaporin family gene sequences has also yielded the identification of new members with novel functions5. After identification, analysis of protein function is typically a next step which can sometimes be examined using a specific assay of protein function such as in the aquaporin case.
When possible, function of a newly identified protein can be examined with specific enzymatic or similar in vitro function assays. Because many functions of novel proteins depend on complex interactions that occur only in intact cells or organisms, in vitro assays are not always effective. However, the in vivo assays must be designed in such a way that they depend on the gene sequence. In cell culture, and/or simple model organisms, knockdown can provide supporting evidence for the protein/function identification6. With novel proteins identified as noted above, it is often insufficient to simply knock down a protein to confirm function, and the design of in vivo functional assays that depend on gene sequence becomes important for the characterization of novel proteins.
The recent identification of TMEM184A as a heparin receptor (that modulates proliferation in vascular smooth muscle and inflammatory responses in endothelial cells) using affinity chromatography and MALDI MS1,7 provided an opportunity to develop a collection of assays after knockdown yielded results consistent with the identification. A recent review confirmed that heparin interacts specifically with many growth factors, their receptors, extracellular matrix components, cell adhesion receptors, and other proteins8. In the vascular system, heparin and heparan sulfate proteoglycans (containing heparan sulfate chains similar in structure to heparin) interact with several hundred proteins9. To functionally confirm that TMEM184A was involved with heparin uptake and binding, techniques that employed the gene construct for TMEM184A were developed. The present report includes a collection of assays based on a GFP-TMEM184A construct for use in confirming the identity of TMEM184A as a heparin receptor.

<table border="0" cellpadding="0" cellspacing="0" width="767">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">GFP-TMEM184A construct</td>
			<td style="width:71px;">OriGene</td>
			<td style="width:119px;">RG213192</td>
			<td style="width:361px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Rhodamine-Heparin</td>
			<td style="width:71px;">Creative PEGWorks</td>
			<td style="width:119px;">HP-204</td>
			<td style="width:361px;">Light Sensitive</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Fluorescein-Heparin</td>
			<td style="width:71px;">Creative PEGWorks</td>
			<td style="width:119px;">HP-201</td>
			<td style="width:361px;">Light Sensitive</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Mowiol</td>
			<td style="width:71px;">EMD Millipore</td>
			<td style="width:119px;">475904-100GM</td>
			<td style="width:361px;"></td>
		</tr>
		<tr height="141">
			<td height="141" style="height:141px;width:216px;">Paraformaldehyde (methanol free)</td>
			<td style="width:71px;">Thermo Sci Pierce Biotech, available through Fisher Scientific</td>
			<td style="width:119px;">PI28908 at Fisher</td>
			<td style="width:361px;">Use in Fume Hood</td>
		</tr>
		<tr height="121">
			<td height="121" style="height:121px;width:216px;">Reacti-bind neutravidin plates (Avidin coated black 96 well dishes)</td>
			<td style="width:71px;">Thermo Sci Pierce Biotech, through Fisher Scientific</td>
			<td style="width:119px;">PI15510 at Fisher</td>
			<td style="width:361px;">Pay attention to shelf-life</td>
		</tr>
		<tr height="161">
			<td height="161" style="height:161px;width:216px;">Black 96 well plates</td>
			<td style="width:71px;">Corning Life Sciences Plastic, purchased through Fisher Scientific</td>
			<td style="width:119px;">064432 at Fisher</td>
			<td style="width:361px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">A7r5 vascular smooth muscle cell line</td>
			<td style="width:71px;">ATCC</td>
			<td style="width:119px;">CRL 1444</td>
			<td style="width:361px;">Can be exchanged into MEM medium1</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">BAOEC bovine aortic endothelial cells</td>
			<td style="width:71px;">Cell Applications, Inc.</td>
			<td style="width:119px;">B304-05</td>
			<td style="width:361px;">Culture as recommended initially, can be exchanged into MEM medium for continuing culture1,7</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">BAOSMC bovine aortic smooth muscle cells</td>
			<td style="width:71px;">Cell Applications, Inc.</td>
			<td style="width:119px;">B354-05</td>
			<td style="width:361px;">Culture as recommended initially, can be exchanged into MEM medium for continuing culture1</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">RAOEC rat aortic endothelial cells</td>
			<td style="width:71px;">Cell Applications, Inc.</td>
			<td style="width:119px;">R304-05a</td>
			<td style="width:361px;">Culture as recommended initially, can be exchanged into MEM medium for continuing culture7</td>
		</tr>
		<tr height="121">
			<td height="121" style="height:121px;width:216px;">Biotinylated anti-GFP</td>
			<td style="width:71px;">Thermo Sci Pierce Biotech, through Fisher Scientific</td>
			<td style="width:119px;">MA5-15256-BTIN</td>
			<td style="width:361px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Streptavidin-coated beads</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">S1638</td>
			<td style="width:361px;"></td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">HeBS</td>
			<td style="width:71px;">Available from Bio-Rad</td>
			<td style="width:119px;"></td>
			<td style="width:361px;">Can be prepared in the lab.&#160; The pH is 6.8</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">TMEM184A antibody to the N-terminus</td>
			<td style="width:71px;">Santa Cruz Biotechnology</td>
			<td style="width:119px;">sc292006</td>
			<td style="width:361px;">Only known TMEM184A antibody to N-terminal region.</td>
		</tr>
		<tr height="101">
			<td height="101" style="height:101px;width:216px;">TMEM184A antibody to the C-terminus</td>
			<td style="width:71px;">Obtained from ProSci Inc, Poway, CA&#160;</td>
			<td style="width:119px;">Pro Sci 5681</td>
			<td style="width:361px;">ProSci used in figure 1</td>
		</tr>
		<tr height="20">
			<td height="41" style="height:41px;width:216px;">GFP antibodies</td>
			<td style="width:71px;">Santa Cruz Biotechnology</td>
			<td style="width:119px;">sc9996</td>
			<td style="width:361px;">Used in figures 5</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:216px;">Secondary antibodies, labeled with TRITC or Cy3</td>
			<td style="width:71px;">Jackson ImmunoResearch Laboratories, Inc, West Grove, PA</td>
			<td style="width:119px;">711 025 152 (donkey anti-rabbit, TRITC) 
			715 165 150 (donkey anti-mouse, Cy3)</td>
			<td style="width:361px;">Minimal cross-reactivity to minimize any non-specific staining.</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">CHAPS</td>
			<td style="width:71px;">Purchased from Sigma</td>
			<td style="width:119px;">C5849</td>
			<td style="width:361px;">Note that this specific catalog number has been discontinued.&#160; Supplier will provide information regarding replacement.</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">Live imaging 35 mm dishes</td>
			<td style="width:71px;">MatTek (Ashland MA)</td>
			<td style="width:119px;">P35G-1.0 &#8211; 20 mm - C</td>
			<td style="width:361px;"></td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">Confocal Microscope</td>
			<td style="width:71px;">Zeiss</td>
			<td style="width:119px;">LSM 510 Meta with a 63X oil-immersion lens</td>
			<td style="width:361px;">Used for images and live-imaging in Figures 1, 2 and 3</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">Confocal Microscope</td>
			<td style="width:71px;">Nikon</td>
			<td style="width:119px;">C2+ confocal with a 60X oil-immersion lens</td>
			<td style="width:361px;">Used for images in Figure 5</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">Confocal Microscope</td>
			<td style="width:71px;">Zeiss</td>
			<td style="width:119px;">Zeiss LSM 880 with a 63X oil-immersion lens</td>
			<td style="width:361px;">Used for images in Figure 2C</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Electroporation equipment</td>
			<td style="width:71px;">Bio-Rad</td>
			<td style="width:119px;">Gene Pulser X-Cell System</td>
			<td style="width:361px;"></td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">Electroporation cuvettes</td>
			<td style="width:71px;">Available from MidSci</td>
			<td style="width:119px;">EC2L</td>
			<td style="width:361px;">Can also be obtained from equipment supplier</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">Plate reader</td>
			<td style="width:71px;">TECAN</td>
			<td style="width:119px;">TECAN Infinite&#174; m200 Pro plate reader</td>
			<td style="width:361px;">Readings in the middle of the wells rather than at the surface.</td>
		</tr>
		<tr height="40">
			<td height="101" style="height:101px;width:216px;">Computer program for measuring staining intensity</td>
			<td style="width:71px;">Image J</td>
			<td style="width:119px;">https://imagej.nih.gov/ij/ 
			Program and information available on-line</td>
			<td style="width:361px;">Any appropriate program can be used. See https://theolb.readthedocs.io/en/latest/imaging/measuring-cell-fluorescence-using-imagej.html for additional detail&#160;&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Cell Culture trypsin solution</td>
			<td style="width:71px;">Sigma</td>
			<td>T4174</td>
			<td style="width:361px;">purchased as a 10X solution</td>
		</tr>
	</tbody>
</table>

using a gfp-tagged tmem184a construct for confirmation of heparin receptor identity

When novel proteins are identified through affinity-based isolation and bioinformatics analysis, they are often largely uncharacterized. Antibodies against specific peptides within the predicted sequence allow some localization experiments. However, other possible interactions with the antibodies often cannot be excluded. This situation provided an opportunity to develop a set of assays dependent on the protein sequence. Specifically, a construct containing the gene sequence coupled to the GFP coding sequence at the C-terminal end of the protein was obtained and employed for these purposes. Experiments to characterize localization, ligand affinity, and gain of function were originally designed and carried out to confirm the identification of TMEM184A as a heparin receptor1. In addition, the construct can be employed for studies addressing membrane topology questions and detailed protein-ligand interactions. The present report presents a range of experimental protocols based on the GFP-TMEM184A construct expressed in vascular cells that could easily be adapted for other novel proteins.

While, in theory, transfection of any DNA construct into cells could be accomplished with lipophilic transfection reagents, previous reports indicate more effective transfection of GFP constructs into endothelial cells using electroporation12. The protocol provided here typically achieved GFP-construct expression in greater than 80% of the primary-derived endothelial cells and smooth muscle cells used. Design of the construct employed used a commercially available ...

Watch this Scientific Journal Video about Using a GFP-tagged TMEM184A Construct for Confirmation of Heparin Receptor Identity at JoVE.com

Using a GFP-tagged TMEM184A Construct for Confirmation of Heparin Receptor Identity

A construct encoding TMEM184A with a GFP tag at the carboxy-terminus designed for eukaryotic expression, was employed in assays designed to confirm the identification of TMEM184A as a heparin receptor in vascular cells.

When novel proteins are identified through affinity-based isolation and bioinformatics analysis, they are often largely uncharacterized. Antibodies ...

The overall goal of using a GFP-tagged construct is to confirm the identity of a previously unknown protein using the GFP as a handle. This method can help with the functional identification of orphan genes when a specific enzyme activity is not available for confirmation. The main advantage of this technique is that the GPF-tag allows the same construct to be used for several types of experiments.Generally, individuals who are new to this method may have trouble, because the transfection does not always result in the strong-construct expression, and the cells do not always revive. We first had the idea for this method, when we began to recognize the difficulties of identifying a protein using only antibodies created against it. Begin by resuspending the cells of interest in one milliliter of HEPES-buffered saline electroporation buffer and immediately place the cells on ice.Add a sufficient volume of GFP-TMEM184A-tagged plasma to the cells to achieve a final concentration of 20 micrograms per milliliter of DNA, and transfer approximately 0.4 milliliters of cells into a pre-chilled electroporation cuvette. Electroporate the cells. Then see the transfected cells onto tissue culture dishes, and place the dishes in a cell culture incubator for 24 to 72 hours.The transfection step is the most critical step of the procedure, because most of the remaining experimental work cannot be effectively completed if the cells are not viable, and do not express significant levels of the GFP-tagged construct. At the appropriate experimental time point, add 100 micrograms per milliliter of Rhodamine Heparin to the GFP-plasmid-expressing cell culture medium, and incubate the cells, protected from light, until the desired level of staining is reached as observed by fluorescence microscopy. Next, rinse the cells with PBS and a few seconds of gentle shaking, protected from light, followed by fixation with 4%paraformaldehyde for 15 minutes at room tempurature with gentle shaking.To assess the GFP-tagged Rhodamine Heparin co-localization, use a confocal microscope with the appropriate GFP and Rhodamine excitation and diminished lasers to image at least 50 cells from each separate labeling experiment. Examine the images in the appropriate image-analysis program to determine the relative Rhodamine finding and uptake in each cell, using a free-hand tool to circle the cells within each fluorescent image. Use the measure tool to determine the intensity within each circled space, then export the fluorescence-intensity data to a spreadsheet to calculate the area multiplied by the intensity, subtracting the background for the same amount of area for each cell.The fluorescence per cell can then be averaged for all of the cells, to obtain statistically significant data. To facilitate the fluorescence resonance energy transfer from GFP TMEM184A to Rhodamine Heparin, first mount fixed GFP TMEM184A transfected Rhodamine Heparin-labeled cells onto glass microscope slides. Excite the cells at 405 nanometers for imaging the Rhodamine emission, followed by excitation of 488 nanometers to image the GFP emission.Then excite the cells at 561 nanometers for a second Rhodamine emission imaging. For live-cell imaging of the Rhodamine Heparin uptake, seed a 100-milliliter confluent dish culture of the GFP TMEM184A-transfected cells into 635 millimeter live-cell imaging dishes to obtain cells near confluence. After 48 hours, replace the supernatant with culture medium without Phenol red, and transfer a dish of cells to a confocal microscope with a warming stage set to 37 degrees Celsius.Focus the microscope, and add 100 micrograms per milliliter of Rhodamine Heparin to the cells with gentle mixing. Then immediately begin recording the live images. If no Heparin uptake occurs within the field of view, move the dish slightly to identify the cells with at least one green vesicle, containing the Rhodamine label.For Heparin-binding assessment in vitro, rinse one black ativan-coated 96 well plate and one black non-coated 96 well plate with 200 microliters of 0.2%CHAPS PBS pro-well for three five-minute washes with shaking. After the last wash, add 100 microliters of 60 picomoles per well of biotinylated anti-GFP in triplicate to the ativan-coated plate for each GFP finding group. Next, add buffer only to the control wells and seal all of the wells with a plate cover for a two-hour incubation at room tempurature with shaking.At the end of the incubation, wash all of the wells three times in CHAPS PBS, as just demonstrated, and add 100 microliters of five nanomoles per well of GFP TMEM184A, or GFP alone, to the appropriate wells in the ativan-coated plate. After a one-hour incubation at room tempurature with shaking, wash all of the wells with fresh CHAPS PBS, and add 100 microliters of each experimental fluorescein-Heparin concentration, to the appropriate test wells in triplicate, to the ativan-coated plate. Add the concentration standards to both the ativan-coated and non-coated plates, and incubate both plates for 10 minutes at room tempurature, with shaking, protected from light.Now, use a plate reader to record the initial Heparin-fluorescence emission in the control wells of both plates, and the initial total fluorescence emission from the wells with the immobilized GFP or GFP TMEM184A in the ativan-coated plate. Then transfer the unbound fluorescent Heparin from the wells with the immobilized GFP TMEM184A or GFP into the corresponding wells in the non-coated black plate. After immediately reading the fluorescence emission on the non-coated black plate, add 100 microliters of fresh CHAPS PBS back into wells from which the fluorescein-Heparin was removed, and read the fluorescence emissions for these wells to obtain the fluorescence emission from the removed, unbound samples in the non-coated plate.When all of the unbound readings have been obtained, use the total Heparin emission values to confirm the correct levels of Heparin were added to each well, by subtracting the average background readings from the values. Then create a plot of the emission versus the total fluorescein-Heparin added, to determine the scale of the emission versus the amount of Heparin, and plot the corrected bound Heparin, versus the added Heparin for the triplicates from both of the GFP and GFP TMEM184A wells. The length of time after transfection impacts the distribution of the GFP TMEM184A, which appears to accumulate over at least 72 hours, with more GFP apparent in the paranuclear region over time.The staining pattern of GFP in this representative vascular cell culture, appears to be most similar to that of an antibody raised against a C-terminal peptide, a logical outcome, given that the GFP is at the C-terminus of the protein. The use of a fluorescein-Rhodamine-Heparin ligand can also be used for the real-time evaluation of ligand receptor co-localization over time. Heparin uptake is increased in GFP TMEM184A construct transfected stable knockdown cells, resulting in cells that can regain the ability to internalize Rhodamine Heparin at or above the level of wild-type cells.Using the demonstrated plasmid-encoded GFP tact system, the anti-GFP antibody isolated GFP TMEM184A construct demonstrates a specific satriple Heparin binding, while the control GFP does not bind any Heparin. Simple immunofluorescence staining with antibodies again GFP can also provide information about the GFP location, based on the antibody access in non-permeabilized cells, providing preliminary evidence that the GFP expressed at the plasma membrane is extra-cellular. Once mastered, this technique can result in excellent GFP-construct expression, after 24 to 48 hours of culture.While attempting the live imaging protocol, it is important to remember that some cells might not exhibit the co-localized uptake, so it is often necessary to examine other cells. Binding assays with GFP ligands can be complicated by dimer or higher-order aggregates of the GFP protein, particularly if they are in detergent micelles. Overall, the expression of GFP-tagged proteins can facilitate a wide variety of experiments to confirm the identity of a previously-unknown protein.

using-gfp-tagged-tmem184a-construct-for-confirmation-heparin-receptor

Research

JoVE Journal

Genetics

Procedure for Adaptive Laboratory Evolution of Microorganisms Using a Chemostat

Natural evolution involves genetic diversity such as environmental change and a selection between small populations. Adaptive laboratory evolution (ALE) refers to the experimental situation in which evolution is observed using living organisms under controlled conditions and stressors; organisms are thereby artificially forced to make evolutionary changes. Microorganisms are subject to a variety of stressors in the environment and are capable of regulating certain stress-inducible proteins to increase their chances of survival. Naturally occurring spontaneous mutations bring about changes in a microorganism's genome that affect its chances of survival. Long-term exposure to chemostat culture provokes an accumulation of spontaneous mutations and renders the most adaptable strain dominant. Compared to the colony transfer and serial transfer methods, chemostat culture entails the highest number of cell divisions and, therefore, the highest number of diverse populations. Although chemostat culture for ALE requires more complicated culture devices, it is less labor intensive once the operation begins. Comparative genomic and transcriptome analyses of the adapted strain provide evolutionary clues as to how the stressors contribute to mutations that overcome the stress. The goal of the current paper is to bring about accelerated evolution of microorganisms under controlled laboratory conditions.

Here, we present a protocol to obtain adaptive laboratory evolution of microorganisms under conditions using chemostat culture. Also, genomic analysis of the evolved strain is discussed.

Natural evolution involves genetic diversity such as environmental change and a selection between small populations. Adaptive laboratory evolution (ALE) ...

Detection of Copy Number Alterations Using Single Cell Sequencing

Detection of genomic changes at single cell resolution is important for characterizing genetic heterogeneity and evolution in normal tissues, cancers, and microbial populations. Traditional methods for assessing genetic heterogeneity have been limited by low resolution, low sensitivity, and/or low specificity. Single cell sequencing has emerged as a powerful tool for detecting genetic heterogeneity with high resolution, high sensitivity and, when appropriately analyzed, high specificity. Here we provide a protocol for the isolation, whole genome amplification, sequencing, and analysis of single cells. Our approach allows for the reliable identification of megabase-scale copy number variants in single cells. However, aspects of this protocol can also be applied to investigate other types of genetic alterations in single cells.

Single cell sequencing is an increasingly popular and accessible tool for addressing genomic changes at high resolution. We provide a protocol that uses single cell sequencing to identify copy number alterations in single cells.

Detection of genomic changes at single cell resolution is important for characterizing genetic heterogeneity and evolution in normal tissues, cancers, and ...

Determination of the Optimal Chromosomal Location(s) for a DNA Element in Escherichia coli Using a Novel Transposon-mediated Approach

The optimal chromosomal position(s) of a given DNA element was/were determined by transposon-mediated random insertion followed by fitness selection. In bacteria, the impact of the genetic context on the function of a genetic element can be difficult to assess. Several mechanisms, including topological effects, transcriptional interference from neighboring genes, and/or replication-associated gene dosage, may affect the function of a given genetic element. Here, we describe a method that permits the random integration of a DNA element into the chromosome of Escherichia coli and select the most favorable locations using a simple growth competition experiment. The method takes advantage of a well-described transposon-based system of random insertion, coupled with a selection of the fittest clone(s) by growth advantage, a procedure that is easily adjustable to experimental needs. The nature of the fittest clone(s) can be determined by whole-genome sequencing on a complex multi-clonal population or by easy gene walking for the rapid identification of selected clones. Here, the non-coding DNA region DARS2, which controls the initiation of chromosome replication in E. coli, was used as an example. The function of DARS2 is known to be affected by replication-associated gene dosage; the closer DARS2 gets to the origin of DNA replication, the more active it becomes. DARS2 was randomly inserted into the chromosome of a DARS2-deleted strain. The resultant clones containing individual insertions were pooled and competed against one another for hundreds of generations. Finally, the fittest clones were characterized and found to contain DARS2 inserted in close proximity to the original DARS2 location.

Determination of the Optimal Chromosomal Locations for a DNA Element in Escherichia coli Using a Novel Transposon-mediated Approach

Here, the power of a transposon-mediated random insertion of a non-coding DNA element was used to resolve its optimal chromosomal position.

The optimal chromosomal position(s) of a given DNA element was/were determined by transposon-mediated random insertion followed by fitness selection. In ...

High-resolution Melting PCR for Complement Receptor 1 Length Polymorphism Genotyping: An Innovative Tool for Alzheimer's Disease Gene Susceptibility Assessment

Complement receptor 1 (CR1), a transmembrane glycoprotein that plays a key role in the innate immune system, is expressed on many cell types, but especially on red blood cells (RBCs). As a receptor for the complement components C3b and C4b, CR1 regulates the activation of the complement cascade and promotes the phagocytosis of immune complexes and cellular debris, as well as the amyloid-beta (A&#946;) peptide in Alzheimer's disease (AD). Several studies have confirmed AD-associated single nucleotide polymorphisms (SNPs), as well as a copy-number variation (CNV) in the CR1 gene. Here, we describe an innovative method for determining the length polymorphism of the CR1 receptor. The receptor includes three domains, called long homologous repeats (LHR)-LHR-A, LHR-C, and LHR-D-and an n domain, LHR-B, where n is an integer between 0 and 3. Using a single pair of specific primers, the genetic material is used to amplify a first fragment of the LHR-B domain (the variant amplicon B) and a second fragment of the LHR-C domain (the invariant amplicon). The variant amplicon B and the invariant amplicon display differences at five nucleotides outside of the hybridization areas of said primers. The numbers of variant amplicons B and of invariant amplicons is deduced using a quantitative tool (high-resolution melting (HRM) curves), and the ratio of the variant amplicon B to the invariant amplicon differs according to the CR1 length polymorphism. This method provides several advantages over the canonical phenotype method, as it does not require fresh material and is cheaper, faster, and therefore applicable to larger populations. Thus, the use of this method should be helpful to better understand the role of CR1 isoforms in the pathogenesis of diseases such as AD.

High-resolution Melting PCR for Complement Receptor 1 Length Polymorphism Genotyping: An Innovative Tool for Alzheimer&#039;s Disease Gene Susceptibility Assessment

Here, we describe an innovative method to determine complement receptor 1 (CR1) length polymorphisms for use in several applications, particularly the assessment of susceptibility to diseases such as Alzheimer&#39;s disease (AD). This method could be useful to better understand the role of CR1 isoforms in the pathogenesis of AD.

Complement receptor 1 (CR1), a transmembrane glycoprotein that plays a key role in the innate immune system, is expressed on many cell types, but ...

A Method to Study the C924T Polymorphism of the Thromboxane A2 Receptor Gene

The thromboxane A2 receptor (TBXA2R) gene is a member of the G-protein coupled superfamily with seven-transmembrane regions. It is involved in atherogenesis progression, ischemia, and myocardial infarction. Here we present a methodology of patient genotyping to investigate the post-transcriptional role of the C924T polymorphism (rs4523) situated at the 3&#39; region of the TBXA2 receptor gene. This method relies on DNA extraction from whole blood, polymerase chain reaction (PCR) amplification of the TBXA2 gene portion containing the C924T mutation, and identification of wild type and/or mutant genotypes using a restriction digest analysis, specifically a restriction fragment length polymorphism (RFLP) on agarose gel. In addition, the results were confirmed by sequencing the TBXA2R gene. This method features several potential advantages, such as high efficiency and the rapid identification of the C924T polymorphism by PCR and restriction enzyme analysis. This approach allows a predictive study for plaque formation and atherosclerosis progression by analyzing patient genotypes for the TBXA2R C924T polymorphism. Application of this method has the potential to identify subjects who are more susceptible to atherothrombotic processes, in particular subjects in a high-risk, aspirin-treated group.

In the present study, we describe a methodology to analyze the C924T genotype. The protocol consists of three phases: DNA extraction, amplification by polymerase chain reaction (PCR), and analysis of the restriction fragment length polymorphism (RFLP) on agarose gel.

The thromboxane A2 receptor (TBXA2R) gene is a member of the G-protein coupled superfamily with seven-transmembrane regions. It is involved in ...

An Ecdysone Receptor-based Singular Gene Switch for Deliberate Expression of Transgene with Robustness, Reversibility, and Negligible Leakiness

Precise control of transgene expression is desirable in biological and clinical studies. However, because the binary feature of currently employed gene switches requires the transfer of two therapeutic expression units concurrently into a single cell, the practical application of the system for gene therapy is limited. To simplify the transgene expression system, we generated a gene switch designated as pEUI(+) encompassing a complete set of transgene expression modules in a single vector. Comprising of the GAL4 DNA-binding domain and modified EcR (GvEcR), a minimal VP16 activation domain fused with a GAL4 DNA-binding domain, as well as a modified Drosophila ecdysone receptor (EcR), the newly developed singular gene switch is highly responsive to the administration of a chemical inducer in a time- and dosage-dependent manner. The pEUI(+) vector is a potentially powerful tool for improving the control of transgene expression in both biological research and pre-clinical studies. Here, we present a detailed protocol for modulation of a transient and stable transgene expression using pEUI(+) vector by the treatment of tebufenozide (Teb). Additionally, we share important guidelines for the use of Teb as a chemical inducer.

Here, we present a protocol for the modulation of transgene expression using pEUI(+) singular gene switch by tebufenozide treatment.

Precise control of transgene expression is desirable in biological and clinical studies. However, because the binary feature of currently employed gene ...

High-throughput Identification of Gene Regulatory Sequences Using Next-generation Sequencing of Circular Chromosome Conformation Capture (4C-seq)

The identification of regulatory elements for a given target gene poses a significant technical challenge owing to the variability in the positioning and effect sizes of regulatory elements to a target gene. Some progress has been made with the bioinformatic prediction of the existence and function of proximal epigenetic modifications associated with activated gene expression using conserved transcription factor binding sites. Chromatin conformation capture studies have revolutionized our ability to discover physical chromatin contacts between sequences and even within an entire genome. Circular chromatin conformation capture coupled with next-generation sequencing (4C-seq), in particular, is designed to discover all possible physical chromatin interactions for a given sequence of interest (viewpoint), such as a target gene or a regulatory enhancer. Current 4C-seq strategies directly sequence from within the viewpoint but require numerous and diverse viewpoints to be simultaneously sequenced to avoid the technical challenges of uniform base calling (imaging) with next generation sequencing platforms. This volume of experiments may not be practical for many laboratories. Here, we report a modified approach to the 4C-seq protocol that incorporates both an additional restriction enzyme digest and qPCR-based amplification steps that are designed to facilitate a greater capture of diverse sequence reads and mitigate the potential for PCR bias, respectively. Our modified 4C method is amenable to the standard molecular biology lab for assessing chromatin architecture.

High-throughput Identification of Gene Regulatory Sequences Using Next-generation Sequencing of Circular Chromosome Conformation Capture 4C-seq

The identification of physical interactions between genes and regulatory elements is challenging but has been facilitated by chromosome conformation capture methods. This modification to the 4C-seq protocol mitigates PCR bias by minimizing over-amplification of PCR templates and maximizes the mappability of reads by incorporating an addition restriction enzyme digest step.

The identification of regulatory elements for a given target gene poses a significant technical challenge owing to the variability in the positioning and ...

Endogenous Protein Tagging in Human Induced Pluripotent Stem Cells Using CRISPR/Cas9

A protocol is presented for generating human induced pluripotent stem cells (hiPSCs) that express endogenous proteins fused to in-frame&#160;N- or C-terminal fluorescent tags. The prokaryotic CRISPR/Cas9 system (clustered regularly interspaced short palindromic repeats/CRISPR-associated 9) may be used to introduce large exogenous sequences into genomic loci via homology directed repair (HDR). To achieve the desired knock-in, this protocol employs the ribonucleoprotein (RNP)-based approach where wild type Streptococcus pyogenes Cas9 protein, synthetic 2-part guide RNA (gRNA), and a donor template plasmid are delivered to the cells via electroporation. Putatively edited cells expressing the fluorescently tagged proteins are enriched by fluorescence activated cell sorting (FACS). Clonal lines are then generated and can be analyzed for precise editing outcomes. By introducing the fluorescent tag at the genomic locus of the gene of interest, the resulting subcellular localization and dynamics of the fusion protein can be studied under endogenous regulatory control, a key improvement over conventional overexpression systems. The use of hiPSCs as a model system for gene tagging provides the opportunity to study the tagged proteins in diploid, nontransformed cells. Since hiPSCs can be differentiated into multiple cell types, this approach provides the opportunity to create and study tagged proteins in a variety of isogenic cellular contexts.

Described here is a protocol for tagging endogenously expressed proteins with fluorescent tags in human induced pluripotent stem cells using CRISPR/Cas9. Putatively edited cells are enriched by fluorescence activated cell sorting and clonal cell lines are generated.

A protocol is presented for generating human induced pluripotent stem cells (hiPSCs) that express endogenous proteins fused to in-frame&#160;N- or ...

qKAT: Quantitative Semi-automated Typing of Killer-cell Immunoglobulin-like Receptor Genes

Killer cell immunoglobulin-like receptors (KIRs) are a set of inhibitory and activating immune receptors, on natural killer (NK) and T cells, encoded by a polymorphic cluster of genes on chromosome 19. Their best-characterized ligands are the human leukocyte antigen (HLA) molecules that are encoded within the major histocompatibility complex (MHC) locus on chromosome 6. There is substantial evidence that they play a significant role in immunity, reproduction, and transplantation, making it crucial to have techniques that can accurately genotype them. However, high-sequence homology, as well as allelic and copy number variation, make it difficult to design methods that can accurately and efficiently genotype all KIR genes. Traditional methods are usually limited in the resolution of data obtained, throughput, cost-effectiveness, and the time taken for setting up and running the experiments. We describe a method called quantitative KIR semi-automated typing (qKAT), which is a high-throughput multiplex real-time polymerase chain reaction method that can determine the gene copy numbers for all genes in the KIR locus. qKAT is a simple high-throughput method that can provide high-resolution KIR copy number data, which can be further used to infer the variations in the structurally polymorphic haplotypes that encompass them. This copy number and haplotype data can be beneficial for studies on large-scale disease associations, population genetics, as well as investigations on expression and functional interactions between KIR and HLA.

Quantitative killer cell immunoglobulin-like receptor (KIR) semi-automated typing (qKAT) is a simple, high-throughput, and cost-effective method to copy number type KIR genes for their application in population and disease association studies.

Killer cell immunoglobulin-like receptors (KIRs) are a set of inhibitory and activating immune receptors, on natural killer (NK) and T cells, encoded by a ...

Mass Spectrometry-Based Proteomics Analyses Using the OpenProt Database to Unveil Novel Proteins Translated from Non-Canonical Open Reading Frames

Genome annotation is central to today's proteomic research as it draws the outlines of the proteomic landscape. Traditional models of open reading frame (ORF) annotation impose two arbitrary criteria: a minimum length of 100 codons and a single ORF per transcript. However, a growing number of studies report expression of proteins from allegedly non-coding regions, challenging the accuracy of current genome annotations. These novel proteins were found encoded either within non-coding RNAs, 5' or 3' untranslated regions (UTRs) of mRNAs, or overlapping a known coding sequence (CDS) in an alternative ORF. OpenProt is the first database that enforces a polycistronic model for eukaryotic genomes, allowing annotation of multiple ORFs per transcript. OpenProt is freely accessible and offers custom downloads of protein sequences across 10 species. Using OpenProt database for proteomic experiments enables novel proteins discovery and highlights the polycistronic nature of eukaryotic genes. The size of OpenProt database (all predicted proteins) is substantial and need be taken in account for the analysis. However, with appropriate false discovery rate (FDR) settings or the use of a restricted OpenProt database, users will gain a more realistic view of the proteomic landscape. Overall, OpenProt is a freely available tool that will foster proteomic discoveries.

OpenProt is a freely accessible database that enforces a polycistronic model of eukaryotic genomes. Here, we present a protocol for the use of OpenProt databases when interrogating mass spectrometry datasets. Using OpenProt database for analysis of proteomic experiments allows for discovery of novel and previously undetectable proteins.

Genome annotation is central to today's proteomic research as it draws the outlines of the proteomic landscape. Traditional models of open reading frame ...