Name: parallel interrogation of &#946;-arrestin2 recruitment for ligand screening on a gpcr-wide scale using presto-tango assay
Uploaded: 2020-03-10T14:30:00
Description: Watch this Scientific Journal Video about Parallel Interrogation of Î²-Arrestin2 Recruitment for Ligand Screening on a GPCR-Wide Scale using PRESTO-Tango Assay at JoVE.com

This work was supported by the Canadian Institutes of Health Research (CIHR grant #MOP142219).

1. Primary screening: cell culture and plate seeding
<ol>
	<li>To prepare poly-L-lysine (PLL)-coated plates, dispense 20 &#956;L/well of a 25 &#956;g/mL stock solution of PLL in white or black 384-well optical bottom plates using an electronic multichannel pipette or a reagent dispenser. Incubate the plates at room temperature for 0.5&#8211;2 h. 
	NOTE: If using the black 384-well plates, expect the background signal to be lower compared to the white plates. Black plates are recommended to reduce bleed-through of ...

<ol>
	<li>Liapakis, 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=The+G-protein+coupled+receptor+family:+actors+with+many+faces.">The G-protein coupled receptor family: actors with many faces.</a> Current pharmaceutical design. 18 (2), 175-185 (2012).</li><li>Pierce, K. L., Premont, R. T., Lefkowitz, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Seven-transmembrane+receptors.">Seven-transmembrane receptors.</a> Nature Reviews Molecular Cell Biology. 3 (9), 639-650 (2002).</li><li>Kroeze, W. K., Sheffler, D. J., Roth, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=G-protein-coupled+receptors+at+a+glance.">G-protein-coupled receptors at a glance.</a> Journal of cell science. 116, 4867-4869 (2003).</li><li>Rask-Andersen, M., Alm&#233;n, M. S., Schi&#246;th, H. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trends+in+the+exploitation+of+novel+drug+targets.">Trends in the exploitation of novel drug targets.</a> Nature Reviews Drug Discovery. 10 (8), 579-590 (2011).</li><li>Ngo, T., 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=Identifying+ligands+at+orphan+GPCRs:+current+status+using+structure-based+approaches.">Identifying ligands at orphan GPCRs: current status using structure-based approaches.</a> British journal of pharmacology. 173 (20), 2934-2951 (2016).</li><li>Zhang, R., Xie, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tools+for+GPCR+drug+discovery.">Tools for GPCR drug discovery.</a> Acta pharmacologica Sinica. 33 (3), 372-384 (2012).</li><li>Kimple, A. J., Bosch, D. E., Giguere, P. M., Siderovski, D. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulators+of+G-Protein+Signaling+and+Their+G+Substrates:+Promises+and+Challenges+in+Their+Use+as+Drug+Discovery+Targets.">Regulators of G-Protein Signaling and Their G Substrates: Promises and Challenges in Their Use as Drug Discovery Targets.</a> Pharmacological Reviews. 63 (3), 728-749 (2011).</li><li>Wettschureck, N., Offermanns, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mammalian+G+Proteins+and+Their+Cell+Type+Specific+Functions.">Mammalian G Proteins and Their Cell Type Specific Functions.</a> Physiological Reviews. 85 (4), 1159-1204 (2005).</li><li>Denis, C., Sauli&#232;re, A., Galandrin, S., S&#233;nard, J. -. M., Gal&#233;s, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+heterotrimeric+G+protein+activation:+applications+to+biased+ligands.">Probing heterotrimeric G protein activation: applications to biased ligands.</a> Current Pharmaceutical Design. 18 (2), 128-144 (2012).</li><li>Yin, H., 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=Lipid+G+protein-coupled+receptor+ligand+identification+using+beta-arrestin+PathHunter+assay.">Lipid G protein-coupled receptor ligand identification using beta-arrestin PathHunter assay.</a> The Journal of Biological Chemistry. 284 (18), 12328-12338 (2009).</li><li>Cheng, 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=Luciferase+Reporter+Assay+System+for+Deciphering+GPCR+Pathways.">Luciferase Reporter Assay System for Deciphering GPCR Pathways.</a> Current Chemical Genomics. 4, 84-91 (2010).</li><li>Roth, B. L., Kroeze, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrated+Approaches+for+Genome-wide+Interrogation+of+the+Druggable+Non-olfactory+G+Protein-coupled+Receptor+Superfamily.">Integrated Approaches for Genome-wide Interrogation of the Druggable Non-olfactory G Protein-coupled Receptor Superfamily.</a> The Journal of Biological Chemistry. 290 (32), 19471-19477 (2015).</li><li>Jean-Charles, P. -. Y., Kaur, S., Shenoy, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=G+Protein-Coupled+Receptor+Signaling+Through+&#946;-Arrestin-Dependent+Mechanisms.">G Protein-Coupled Receptor Signaling Through &#946;-Arrestin-Dependent Mechanisms.</a> Journal of Cardiovascular Pharmacology. 70 (3), 142-158 (2017).</li><li>Smith, J. S., Rajagopal, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+&#946;-Arrestins:+Multifunctional+Regulators+of+G+Protein-coupled+Receptors.">The &#946;-Arrestins: Multifunctional Regulators of G Protein-coupled Receptors.</a> The Journal of Biological Chemistry. 291 (17), 8969-8977 (2016).</li><li>B&#246;hme, I., Beck-Sickinger, A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Illuminating+the+life+of+GPCRs.">Illuminating the life of GPCRs.</a> Cell Communication and Signaling. 7 (1), 16 (2009).</li><li>Fang, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Label-Free+Receptor+Assays.">Label-Free Receptor Assays.</a> Drug discovery today. Technologies. 7 (1), 5-11 (2011).</li><li>Wang, T., 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=Measurement+of+&#946;-Arrestin+Recruitment+for+GPCR+Targets.+Assay+Guidance+Manual.">Measurement of &#946;-Arrestin Recruitment for GPCR Targets. Assay Guidance Manual.</a> Eli Lilly &amp; Company and the National Center for Advancing Translational Sciences. , (2004).</li><li>Barnea, 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=The+genetic+design+of+signaling+cascades+to+record+receptor+activation.">The genetic design of signaling cascades to record receptor activation.</a> Proceedings of the National Academy of Sciences of the United States of America. 105 (1), 64-69 (2008).</li><li>Kroeze, W. 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=PRESTO-Tango+as+an+open-source+resource+for+interrogation+of+the+druggable+human+GPCRome.">PRESTO-Tango as an open-source resource for interrogation of the druggable human GPCRome.</a> Nature Structural &amp; Molecular Biology. 22 (5), 362-369 (2015).</li><li>Jordan, M., Schallhorn, A., Wurm, F. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transfecting+Mammalian+Cells:+Optimization+of+Critical+Parameters+Affecting+Calcium-Phosphate+Precipitate+Formation.">Transfecting Mammalian Cells: Optimization of Critical Parameters Affecting Calcium-Phosphate Precipitate Formation.</a> Nucleic Acids Research. 24 (4), 596-601 (1996).</li><li>Baker, J. M., Boyce, F. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-throughput+functional+screening+using+a+homemade+dual-glow+luciferase+assay.">High-throughput functional screening using a homemade dual-glow luciferase assay.</a> Journal of Visualized Experiments. (88), 50282 (2014).</li><li>Li, H., Eishingdrelo, A., Kongsamut, S., Eishingdrelo, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=G-protein-coupled+receptors+mediate+14-3-3+signal+transduction.">G-protein-coupled receptors mediate 14-3-3 signal transduction.</a> Signal Transduction and Targeted Therapy. 1 (1), 16018 (2016).</li><li>Walther, C., Ferguson, S. S. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Minireview:+Role+of+intracellular+scaffolding+proteins+in+the+regulation+of+endocrine+G+protein-coupled+receptor+signaling.">Minireview: Role of intracellular scaffolding proteins in the regulation of endocrine G protein-coupled receptor signaling.</a> Molecular Endocrinology. 29 (6), 814-830 (2015).</li><li>Gurevich, E. V., Benovic, J. L., Gurevich, V. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arrestin2+expression+selectively+increases+during+neural+differentiation.">Arrestin2 expression selectively increases during neural differentiation.</a> Journal of Neurochemistry. 91 (6), 1404-1416 (2004).</li><li>Shaikh, S., Nicholson, L. F. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimization+of+the+Tet-On+system+for+inducible+expression+of+RAGE.">Optimization of the Tet-On system for inducible expression of RAGE.</a> Journal of Biomolecular Techniques JBT. 17 (4), 283-292 (2006).</li><li>Blau, H. M., Rossi, F. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tet+B+or+not+tet+B:+advances+in+tetracycline-inducible+gene+expression.">Tet B or not tet B: advances in tetracycline-inducible gene expression.</a> Proceedings of the National Academy of Sciences of the United States of America. 96 (3), 797-799 (1999).</li><li>Roche, 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=Development+of+a+Virtual+Screening+Method+for+Identification+of+"Frequent+Hitters"+in+Compound+Libraries.">Development of a Virtual Screening Method for Identification of "Frequent Hitters" in Compound Libraries.</a> Journal of Medicinal Chemistry. 45 (1), 137-142 (2002).</li></ol>

The conformationally dynamic GPCRs are powerhouses of signal transduction. The physiochemical properties of the binding pockets of these heptahelical receptors, as well as their physiological relevance underscore the need for GPCR ligand screening tools. As presented above, the PRESTO-Tango assay is rapid, sensitive and user-friendly, lending itself to drug development. Not only does this assay measure agonist-induced activation, but it can also be used to quantify the activity of antagonists and allosteric modulators<su...

G-protein-coupled receptors (GPCRs) constitute the largest and most diverse family of transmembrane proteins, operating as communication interfaces between a cell and its environment1. The versatility of GPCRs is highlighted by their ability to detect a diverse array of ligands&#8211;from neurotransmitters to nucleotides, peptides to photons, and many more&#8211;as well as their ability to regulate numerous downstream signaling cascades involved in cellular growth, migration, differentiation, apoptosis, cell firing, etc.2,3. Considering their ubiquity and involvement in a multitude of physiological processes, this receptor family is of utmost therapeutic importance, showcased by the fact that more than a third of currently available prescribed medications target GPCRs4. However, these existing therapeutics only target a small subset of the superfamily (an estimated 10%), and the pharmacology of many GPCRs remains unelucidated. Moreover, more than 100 GPCRs exist as orphan receptors, as they have not been matched with an endogenous ligand5. Thus, GPCR ligand screening is critical in deorphanization and drug development, as it paves the path towards lead discovery and optimization, and possibly to the clinical trial phase.
Methods for GPCR ligand screening have traditionally fallen in one of two categories, G-protein dependent or G-protein independent functional assays6. GPCR signaling is regulated by heterotrimeric G-proteins (G&#945;&#946;&#947;), which are activated by the exchange of GTP for GDP bound on the G&#945; subunit7. Signals from the activated receptor are transduced by G-proteins via secondary messengers, such as cAMP, Calcium, DAG, and IP3, to mediate downstream signaling at downstream effectors8. The nature of the functional consequences of G-protein signaling has been exploited to create cell-based assays that reflect receptor activation. These methods, which measure proximal (direct) or distal (indirect) events in G-protein signaling, are most frequently used for GPCR ligand screening and have been principally employed in deorphanization studies6. Examples of assays that directly measure GPCR-mediated G-protein activation include the [35S]GTP&#947;S binding assay, which measures binding of a radiolabeled and non-hydrolyzable GTP analog to the G&#945; subunit, and F&#246;rster/bioluminescence resonance energy transfer (FRET/BRET, respectively) probes to monitor GPCR-G&#945; and G&#945;/G&#947; interactions, which have been gaining more traction over the years9,10. Assays that monitor distal events are the most commonly used tools for GPCR profiling; for example, cAMP and IP1/3 assays measure intracellular accumulation of G-protein dependent secondary messengers, whereas [Ca2+] flux and reporter assays involving specific response elements implicated in G-protein activation (CRE, NFAT-RE, SRE, SRF-RE) examine events further downstream the signaling cascade11. While most of the aforementioned assays can be performed at a high-throughput level, are fairly sensitive, and boast certain assay-specific advantages (e.g., discrimination between full/partial agonists, neutral antagonists and inverse agonists in the case of GTP&#947;S binding, or assay functionality on live cells such as [Ca2+] and IP1/3)6, there are unfortunately no existing G-protein dependent methods befitting the interrogation of the entire druggable GPCR-ome. This is largely due to the native coupling of multiple G-protein subfamilies to GPCRs, resulting in signaling at several cascades and the unknown G-protein coupling at orphan GPCRs. To mitigate this issue, assays have been developed to force promiscuous G-protein coupling through a single common signaling read-out, such as cAMP, and Ca2+, albeit most of them are low-throughput12.
An important aspect of the GPCR lifecycle is the termination of G-protein-dependent signaling, which occurs in large part through the recruitment of &#946;-arrestins which induces dissociation of the G-protein, and ultimately desensitizing the receptor, which is targeted for clathrin-coated internalization13. The most ubiquitously expressed isoforms of &#946;-arrestin are the non-visual &#946;-arrestin1 and &#946;-arrestin2, also denoted as arrestin-2 and arrestin-3, respectively14. Enter G-protein independent cell-based assays, which add a new dimension to GPCR ligand screening; receptor trafficking, label-free whole cell, and &#946;-arrestin recruitment assays are all notable examples. GPCR trafficking assays employ fluorophore-labeled ligands or co-internalized antibodies targeting the receptor15, whereas label-free whole cell assays use biosensors which translate cellular changes induced by ligand binding into quantifiable outputs, such as electrical or optical signals16. Notably, quintessential GPCR- &#946;-arrestin interactions fashion the &#946;-arrestin recruitment assay as an attractive tool in the repertoire of functional assays17. The Tango system, first developed by Barnea et al. only a decade ago, involves the introduction of three exogenous genetic elements: a protein fusion consisting of &#946;-arrestin2 with a tobacco etch virus protease (TEVp), a tetracycline transactivator (tTA) that is tethered to a GPCR via a tobacco etch virus protease cleavage site (TEVcs) and is preceded by a sequence from the C-terminus of the V2 vasopressin receptor (V2 tail) to promote arrestin recruitment, and a reporter luciferase gene whose transcription is triggered by the tTA transcription factor translocation to the nucleus, which is freed from the membrane anchoring following &#946;-arrestin2 recruitment (Figure 1)18. Quantitative readings of GPCR activation and &#946;-arrestin2 recruitment can be subsequently determined by reading for luminescence. A notable distinction is that while receptor trafficking and label-free whole cell methods are relatively low-throughput, the Tango has several advantages, including selective read-out that is specific to the target receptor and sensitivity due to signal integration, which make it a suitable candidate for ligand screening on a larger scale18.
In view of these strategic features, Kroeze et al. developed PRESTO-Tango (Parallel Receptor-ome Expression and Screening via Transcriptional Output-Tango), a high-throughput open-source platform that uses the Tango approach to profile the druggable GPCR-ome in a parallel and simultaneous manner19. Exploiting the &#34;promiscuous&#34; recruitment of &#946;-arrestin2 to nearly all GPCRs, PRESTO-Tango is the first-of-its-kind in terms of cell-based functional assays, enabling rapid &#34;first-round&#34; screening of small molecule compounds at almost all non-olfactory GPCRs, including orphans, independent of the G-protein subfamily coupling.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>384 Well Optical Bottom Plates, Polystyrene Polymer Base, Cell Culture Treated, BLACK, with lid, Sterile</td>
			<td>NUNC</td>
			<td>12-566</td>
			<td></td>
		</tr>
		<tr>
			<td>384 Well Optical Bottom Plates, Polystyrene Polymer Base, Cell Culture Treated, White, with lid, Sterile</td>
			<td>NUNC</td>
			<td>12-566-1</td>
			<td></td>
		</tr>
		<tr>
			<td>384 Well Round Bottom, Polypropylene, Non-Treated, Blue, non-sterile, without lid</td>
			<td>ThermoFisher</td>
			<td>12-565-390</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibiotic-Antimycotic</td>
			<td>Wisent</td>
			<td>450-115-EL</td>
			<td></td>
		</tr>
		<tr>
			<td>D-Luciferin, sodium salt</td>
			<td>GoldBio</td>
			<td>LUCNA</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM with L-Glutamine, 4.5g/L Glucose and Sodium Pyruvate</td>
			<td>Corning</td>
			<td>10-013-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Eppendorf Xplorer, 12-channel, variable, 15&#8211;300 &#181;L</td>
			<td>Eppendorf</td>
			<td>4861000155</td>
			<td></td>
		</tr>
		<tr>
			<td>Eppendorf Xplorer, 12-channel, variable, 5&#8211;100 &#181;L</td>
			<td>Eppendorf</td>
			<td>4861000139</td>
			<td></td>
		</tr>
		<tr>
			<td>Matrix Platemate 2x3</td>
			<td>ThermoFisher</td>
			<td>801-10001</td>
			<td></td>
		</tr>
		<tr>
			<td>MicroBeta 1450 Wallac</td>
			<td>Perkin Elmer</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Penicilin-Streptomycin</td>
			<td>Wisent</td>
			<td>450-201-EL</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly-L-Lysine hydrobromide</td>
			<td>Millipore-Sigma</td>
			<td>P2636-500MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Roth Lab PRESTO-Tango GPCR Kit</td>
			<td>Addgene</td>
			<td>Kit #1000000068</td>
			<td></td>
		</tr>
	</tbody>
</table>

parallel interrogation of &#946;-arrestin2 recruitment for ligand screening on a gpcr-wide scale using presto-tango assay

As the largest and most versatile gene superfamily and mediators of a gamut of cellular signaling pathways, G-protein-coupled receptors (GPCRs) represent one of the most promising targets for the pharmaceutical industry. Ergo, the design, implementation, and optimization of GPCR ligand screening assays is crucial, as they represent remote-control tools for drug discovery and for manipulating GPCR pharmacology and outcomes. In the past, G-protein dependent assays typified this area of research, detecting ligand-induced events and quantifying the generation of secondary messengers. However, since the advent of functional selectivity, as well as an increased awareness of several other G protein-independent pathways and the limitations associated with G-protein dependent assays, there is a greater push towards the creation of alternative GPCR ligand screening assays. Towards this endeavor, we describe the application of one such resource, the PRESTO-Tango platform, a luciferase reporter-based system that enables the parallel and simultaneous interrogation of the human GPCR-ome, a feat which was previously considered technically and economically unfeasible. Based on a G-protein independent &#946;-arrestin2 recruitment assay, the universality of &#946;-arrestin2-mediated trafficking and signaling at GPCRs makes PRESTO-TANGO an apt tool for studying approximately 300 non-olfactory human GPCRs, including approximately 100 orphan receptors. PRESTO-Tango&#39;s sensitivity and robustness make it suitable for primary high-throughput screens using compound libraries, employed to uncover new GPCR targets for known drugs or to discover new ligands for orphan receptors.

Using the PRESTO-Tango protocol presented herein, a chromaffin granule (CG) extract was screened against 168 non-olfactory GPCR targets, with the majority being orphan receptors. Profiling of said extract was performed by examining &#946;-arrestin2 mobilization at the chosen receptors, based on the principle designed by Barnea et al.18 (Figure 1). Plasmid cDNA of the GPCRs of interest was taken from the PRESTO-Tango GPCR Kit and assembled in two 96 well-plates in the ...

Watch this Scientific Journal Video about Parallel Interrogation of Î²-Arrestin2 Recruitment for Ligand Screening on a GPCR-Wide Scale using PRESTO-Tango Assay at JoVE.com

Parallel Interrogation of &#946;-Arrestin2 Recruitment for Ligand Screening on a GPCR-Wide Scale using PRESTO-Tango Assay

Given that GPCRs are attractive druggable targets, GPCR ligand screening is thus indispensable for the identification of lead compounds and for deorphanization studies. Towards these efforts, we describe PRESTO-Tango, an open-source resource platform used for simultaneous profiling of transient &#946;-arrestin2 recruitment at approximately 300 GPCRs using a TEV-based reporter assay.

As the largest and most versatile gene superfamily and mediators of a gamut of cellular signaling pathways, G-protein-coupled receptors (GPCRs) represent ...

The Presto-Tango platform was devised to execute the parallel and simultaneous interrogation of all non-olfactory GPCRs in the human genome, including that orphan targets to profile ligand-induced beta-arrestin 2 recruitment. The Presto-Tango platform is the only open source resource for profiling the entire GPCR genome in a parallel approach, using a G protein independent beta-arrestin recruitment assay. Demonstrating the processor would be Genevieve Laroche a Research Associate in my lab, and Manel Zighal, a PhD candidate in my lab.Before beginning the procedure add 20 microliters of a 25 microgram per milliliter poly-L-lysine solution to each well of the appropriate experimental number of 384 optical bottom plates and incubate the plates at room temperature for 30 minutes to two hours. At the end of the incubation, flick the plates over the sink to remove the excess poly-L-lysine and add 40 microliters of antibiotic antimycotic solution to each well. Then incubate the plates needed for cell seeding at 37 degrees Celsius and place the rest of the plates at four degrees Celsius for long term storage.To seed HTLA cells for primary screening, gently rinse confluent 150 millimeters cell cultures with 10 milliliters of PBS before treating the cultures with six milliliters of 0.05%trypsin EDTA per dish. When the cells have detached pool the cell suspensions in a 50 milliliter conical tube containing an equal volume of DMEM. And collect the cells by centrifugation.Re-suspend the pellet at a 2.2 times 10 to the fifth cells per milliliter of DMEM concentration and flick the plates over the sink to remove the antibiotic antimycotic solution. Tap the plates to dry and seed 45 microliters of cells into each well. Then place the plates at 37 degrees Celsius and 45%carbon dioxide overnight.To prepare the 384 well DNA source plate for transfection distribute 50 nanograms per milliliter of each plasmid complimentary DNA encoding the GPRC Tango construct of interest in 0.1X Tris-EDTA per well into each well of a 96 well plate. Use a multi-channel pipette to manually transfer 10 microliters of DNA solution from each well of the 96 well plate to individual wells of one 384 well DNA source plate in quadruplicate for each condition as illustrated. Next, transfer 40 microliters of a 0.313 molar calcium chloride solution to each well of the DNA source plate and gently mix the contents of each well.Add 50 microliters of 2x HEPES buffer to each well of the 384 well DNA source plate with gentle mixing. After one minute transfer 10 microliters of the DNA transfection mixture from the 384 well DNA source plate to each well of seeded HTLA cells and incubate the cells in the cell culture incubator overnight. The next day decant the transfected cell medium and slowly add 40 microliters of starving medium to each well taking care not to touch the cells directly.Then add 20 microliters of the vehicle buffer for the alternating rows without compound in 20 microliters of the compound of interest at a three times concentration into the alternating rows, before returning the plate to the cell culture incubator. 16 to 24 hours following the stimulation decant the transfected cell medium and add 20 microliters of freshly prepared glow reagent to each well for a five to 20 minute incubation at room temperature protected from light. Then read the plates on a micro-plate luminescence counter with an integration time of one second per well.For a secondary screening, subculture the HTLA cells in 100 millimeter dishes at a five times 10 to the six cells total cell density in 11 millimeters of complete medium per dish for 24 hours at 37 degrees Celsius. The next day, mixed 10 micrograms of GPCR complimentary DNA with 500 microliters of Tris-EDTA calcium chloride solution with vortexing followed by the addition of 500 microliters of HEPES buffer. After vigorous shaking, incubate the solution for one minute at room temperature and immediately add one milliliter of the solution drop wise onto the cells.Gently rock to evenly distribute the precipitate and place the plate at 37 degrees Celsius for 24 hours. The next day, check the transfection efficiency under a fluorescent cell imager. Transactions greater than 50%coverage are ideal.Gently rinse the transfected cells with versene solution before detaching the cells with three milliliters of 0.05%trypsin EDTA. Collect the dissociated cells by centrifugation and re-suspend the pellet at a four times 10 to the fifth cells per milliliter of starving medium concentration. Then seed 45 microliters of cells into each well of a poly-L-lysine coded 384 well plate and place the plate in the cell culture incubator for at least four hours.To prepare a half log dose-curve response plate add 270 microliters of HBSS supplemented with HEPES and antibiotic antimycotic to all but the last row of a 96 well plate and add 30 microliters of each high and low drug solution to the wells of row H.Transfer the solution from each well of row H into the corresponding well of row G with mixing and continue to serially dilute the drug compounds until the last row of the plate is reached. Using the schematic as a reference, mix 20 microliters of the low column dilutions from rows A through G of the 96 well plate and 20 microliters of the high column dilutions to wells B through H of the 96 well plate to the previously seated 384 well plate. Then incubate the plate at 37 degrees Celsius for a minimum of 16 hours.16 to 24 hours following the stimulation decant the transfected cell medium and add 20 microliters of glow reagent to each well for a five to 20 minute incubation before reading the plates on a micro plate luminescence counter with an integration time of one second per well. In this representative experiment, out of the 168 GPCRs that were interrogated in the primary screening, only dopamine receptor D3 and opsin 5 were contenders as potential active targets. Dopamine receptor D3 produced a significant log2 fold change of 4.7 whereas opsin 5 produced a slightly lower response of 2.39.By comparison, dopamine receptor D2, the positive control for the primary screen produced a log2 fold change of 4.58. Those response curves from the secondary screening demonstrated that chromatin granule extract produce similar signal windows in half maximal effective concentration values to quinpirole confirming its validity as an active hit at dopamine receptor D3.A flat dose-curve similar to the negative control was produced for opsin 5 however ruling out this receptor as a possible target for the chromatin granule extract. Presto-Tango requires special care as variabilities in cell distribution, transfection efficiency and serial drug dilutions can result in compounded error, which can affect the accuracy of the data.Orthogonal methods such as Radioligand-binding approaches, Bioluminescence Resonance Energy Transfer and Cyclic AMP calcium and internalization functional assays can be used to further confirm and characterize ligand receptor interactions.

parallel-interrogation-arrestin2-recruitment-for-ligand-screening-on

Research

JoVE Journal

Biochemistry

High-throughput Screening of Carbohydrate-degrading Enzymes Using Novel Insoluble Chromogenic Substrate Assay Kits

Carbohydrates active enzymes (CAZymes) have multiple roles in vivo and are widely used for industrial processing in the biofuel, textile, detergent, paper and food industries. A deeper understanding of CAZymes is important from both fundamental biology and industrial standpoints. Vast numbers of CAZymes exist in nature (especially in microorganisms) and hundreds of thousands have been cataloged and described in the carbohydrate active enzyme database (CAZy). However, the rate of discovery of putative enzymes has outstripped our ability to biochemically characterize their activities. One reason for this is that advances in genome and transcriptome sequencing, together with associated bioinformatics tools allow for rapid identification of candidate CAZymes, but technology for determining an enzyme's biochemical characteristics has advanced more slowly. To address this technology gap, a novel high-throughput assay kit based on insoluble chromogenic substrates is described here. Two distinct substrate types were produced: Chromogenic Polymer Hydrogel (CPH) substrates (made from purified polysaccharides and proteins) and Insoluble Chromogenic Biomass (ICB) substrates (made from complex biomass materials). Both CPH and ICB substrates are provided in a 96-well high-throughput assay system. The CPH substrates can be made in four different colors, enabling them to be mixed together and thus increasing assay throughput. The protocol describes a 96-well plate assay and illustrates how this assay can be used for screening the activities of enzymes, enzyme cocktails, and broths.

A high-throughput assay for enzyme screening is described. This multiplexed ready-to-use assay kit comprises of pre-chosen Chromogenic Polymer Hydrogel (CPH) substrates and complex Insoluble Chromogenic Biomass (ICB) substrates. Target enzymes are polysaccharide degrading endo-enzymes and proteases.

Carbohydrates active enzymes (CAZymes) have multiple roles in vivo and are widely used for industrial processing in the biofuel, textile, detergent, paper ...

A Simple Method for High Throughput Chemical Screening in Caenorhabditis Elegans

Caenorhabditis elegans is a useful organism for testing chemical effects on physiology. Whole organism small molecule screens offer significant advantages for identifying biologically active chemical structures that can modify complex phenotypes such as lifespan. Described here is a simple protocol for producing hundreds of 96-well culture plates with fairly consistent numbers of C. elegans in each well. Next, we specified how to use these cultures to screen thousands of chemicals for effects on the lifespan of the nematode C. elegans. This protocol makes use of temperature sensitive sterile strains, agar plate conditions, and simple animal handling to facilitate the rapid and high throughput production of synchronized animal cultures for screening.

A Simple Method for High Throughput Chemical Screening in Caenorhabditis Elegans

Here we describe a simple protocol for rapidly producing hundreds of nematode growth media agar, 96-well culture plates with consistent numbers of Caenorhhabditis elegans per well. These cultures are useful for the phenotypic screening of whole organisms. We focus here on using these cultures to screen chemicals for pro-longevity effects.

Caenorhabditis elegans is a useful organism for testing chemical effects on physiology. Whole organism small molecule screens offer significant advantages ...

Method for Efficient Refolding and Purification of Chemoreceptor Ligand Binding Domain

Identification of natural ligands of chemoreceptors and structural studies aimed at elucidation of the molecular basis of the ligand specificity can be greatly facilitated by the production of milligram amounts of pure, folded ligand binding domains. Attempts to heterologously express periplasmic ligand binding domains of bacterial chemoreceptors in Escherichia coli (E. coli) often result in their targeting into inclusion bodies. Here, a method is presented for protein recovery from inclusion bodies, its refolding and purification, using the periplasmic dCACHE ligand binding domain of Campylobacter jejuni (C. jejuni) chemoreceptor Tlp3 as an example. The approach involves expression of the protein of interest with a cleavable His6-tag, isolation and urea-mediated solubilisation of inclusion bodies, protein refolding by urea depletion, and purification by means of affinity chromatography, followed by tag removal and size-exclusion chromatography. The circular dichroism spectroscopy is used to confirm the folded state of the pure protein. It has been demonstrated that this protocol is generally useful for production of milligram amounts of dCACHE periplasmic ligand binding domains of other bacterial chemoreceptors in a soluble and crystallisable form.

A procedure is presented for the refolding of the dCACHE periplasmic ligand binding domain of Campylobacter jejuni chemoreceptor Tlp3 from inclusion bodies and the purification to yield milligram quantities of protein.

Identification of natural ligands of chemoreceptors and structural studies aimed at elucidation of the molecular basis of the ligand specificity can be ...

Titration ELISA as a Method to Determine the Dissociation Constant of Receptor Ligand Interaction

The dissociation constant describes the interaction between two partners in the binding equilibrium and is a measure of their affinity. It is a crucial parameter to compare different ligands, e.g., competitive inhibitors, protein isoforms and mutants, for their binding strength to a binding partner. Dissociation constants are determined by plotting concentrations of bound versus free ligand as binding curves. In contrast, titration curves, in which a signal that is proportional to the concentration of bound ligand is plotted against the total concentration of added ligand, are much easier to record. The signal can be detected spectroscopically and by enzyme-linked immunosorbent assay (ELISA). This is exemplified in a protocol for a titration ELISA that measures the binding of the snake venom-derived rhodocetin to its immobilized target domain of &#945;2&#946;1 integrin. Titration ELISAs are versatile and widely used. Any pair of interacting proteins can be used as immobilized receptor and soluble ligand, provided that both proteins are pure, and their concentrations are known. The difficulty so far has been to determine the dissociation constant from a titration curve. In this study, a mathematical function underlying titration curves is introduced. Without any error-prone graphical estimation of a saturation yield, this algorithm allows processing of the raw data (signal intensities at different concentrations of added ligand) directly by mathematical evaluation via non-linear regression. Thus, several titration curves can be recorded simultaneously and transformed into a set of characteristic parameters, among them the dissociation constant and the concentration of binding-active receptor, and they can be evaluated statistically. When combined with this algorithm, titration ELISAs gain the advantage of directly presenting the dissociation constant. Therefore, they may be used more efficiently in the future.

A detailed protocol to perform a titration ELISA is described. Moreover, a novel algorithm is presented to evaluate titration ELISAs and to obtain a dissociation constant of binding of a soluble ligand to a microtiter plate-immobilized receptor.

The dissociation constant describes the interaction between two partners in the binding equilibrium and is a measure of their affinity. It is a crucial ...

Large-scale Production of Recombinant RNAs on a Circular Scaffold Using a Viroid-derived System in Escherichia coli

With increasing interest in RNA biology and the use of RNA molecules in sophisticated biotechnological applications, the methods to produce large amounts of recombinant RNAs are limited. Here, we describe a protocol to produce large amounts of recombinant RNA in Escherichia coli based on co-expression of a chimeric molecule that contains the RNA of interest in a viroid scaffold and a plant tRNA ligase. Viroids are relatively small, non-coding, highly base-paired circular RNAs that are infectious to higher plants. The host plant tRNA ligase is an enzyme recruited by viroids that belong to the family Avsunviroidae, such as Eggplant latent viroid (ELVd), to mediate RNA circularization during viroid replication. Although ELVd does not replicate in E. coli, an ELVd precursor is efficiently transcribed by the E. coli RNA polymerase and processed by the embedded hammerhead ribozymes in bacterial cells, and the resulting monomers are circularized by the co-expressed tRNA ligase reaching a remarkable concentration. The insertion of an RNA of interest into the ELVd scaffold enables the production of tens of milligrams of the recombinant RNA per liter of bacterial culture in regular laboratory conditions. A main fraction of the RNA product is circular, a feature that facilitates the purification of the recombinant RNA to virtual homogeneity. In this protocol, a complementary DNA (cDNA) corresponding to the RNA of interest is inserted in a particular position of the ELVd cDNA in an expression plasmid that is used, along the plasmid to co-express eggplant tRNA ligase, to transform E. coli. Co-expression of both molecules under the control of strong constitutive promoters leads to production of large amounts of the recombinant RNA. The recombinant RNA can be extracted from the bacterial cells and separated from the bulk of bacterial RNAs taking advantage of its circularity.

Large-scale Production of Recombinant RNAs on a Circular Scaffold Using a Viroid-derived System in Escherichia coli

Here, we present a protocol to produce large amounts of recombinant RNA in Escherichia coli by co-expressing a chimeric RNA that contains the RNA of interest in a viroid scaffold and a plant tRNA ligase. The main product is a circular molecule that facilitates purification to homogeneity.

With increasing interest in RNA biology and the use of RNA molecules in sophisticated biotechnological applications, the methods to produce large amounts ...

Using In Vitro Fluorescence Resonance Energy Transfer to Study the Dynamics Of Protein Complexes at a Millisecond Time Scale

Proteins are the primary operators of biological systems, and they usually interact with other macro- or small molecules to carry out their biological functions. Such interactions can be highly dynamic, meaning the interacting subunits are constantly associated and dissociated at certain rates. While measuring the binding affinity using techniques such as quantitative pull-down reveals the strength of the interaction, studying the binding kinetics provides insights on how fast the interaction occurs and how long each complex can exist. Furthermore, measuring the kinetics of an interaction in the presence of an additional factor, such as a protein exchange factor or a drug, helps reveal the mechanism by which the interaction is regulated by the other factor, providing important knowledge for the advancement of biological and medical research. Here, we describe a protocol for measuring the binding kinetics of a protein complex that has a high intrinsic association rate and can be dissociated quickly by another protein. The method uses fluorescence resonance energy transfer to report the formation of the protein complex in vitro, and it enables monitoring the fast association and dissociation of the complex in real time on a stopped-flow fluorimeter. Using this assay, the association and dissociation rate constants of the protein complex are quantified.

Protein-protein interactions are critical for biological systems, and studies of the binding kinetics provide insights into the dynamics and function of protein complexes. We describe a method that quantifies the kinetic parameters of a protein complex using fluorescence resonance energy transfer and the stopped-flow technique. &#160;

Proteins are the primary operators of biological systems, and they usually interact with other macro- or small molecules to carry out their biological ...

Kinetic Screening of Nuclease Activity using Nucleic Acid Probes

Nucleases are a class of enzymes that break down nucleic acids by catalyzing the hydrolysis of the phosphodiester bonds that link the ribose sugars. Nucleases display a variety of vital physiological roles in prokaryotic and eukaryotic organisms, ranging from maintaining genome stability to providing protection against pathogens. Altered nuclease activity has been associated with several pathological conditions including bacterial infections and cancer. To this end, nuclease activity has shown great potential to be exploited as a specific biomarker. However, a robust and reproducible screening method based on this activity remains highly desirable.
Herein, we introduce a method that enables screening for nuclease activity using nucleic acid probes as substrates, with the scope of differentiating between pathological and healthy conditions. This method offers the possibility of designing new probe libraries, with increasing specificity, in an iterative manner. Thus, multiple rounds of screening are necessary to refine the probes&#39; design with enhanced features, taking advantage of the availability of chemically modified nucleic acids. The considerable potential of the proposed technology lies in its flexibility, high reproducibility, and versatility for the screening of nuclease activity associated with disease conditions. It is expected that this technology will allow the development of promising diagnostic tools with a great potential in the clinic.

Altered nuclease activity has been associated with different human conditions, underlying its potential as a biomarker. The modular and easy to implement screening methodology presented in this paper allows the selection of specific nucleic acid probes for harnessing nuclease activity as a biomarker of disease.

Nucleases are a class of enzymes that break down nucleic acids by catalyzing the hydrolysis of the phosphodiester bonds that link the ribose sugars. ...

A Semi-High-Throughput Adaptation of the NADH-Coupled ATPase Assay for Screening Small Molecule Inhibitors

ATPase enzymes utilize the free energy stored in adenosine triphosphate to catalyze a wide variety of endergonic biochemical processes in vivo that would not occur spontaneously. These proteins are crucial for essentially all aspects of cellular life, including metabolism, cell division, responses to environmental changes and movement. The protocol presented here describes a nicotinamide adenine dinucleotide (NADH)-coupled ATPase assay that has been adapted to semi-high throughput screening of small molecule ATPase inhibitors. The assay has been applied to cardiac and skeletal muscle myosin II's, two actin-based molecular motor ATPases, as a proof of principle. The hydrolysis of ATP is coupled to the oxidation of NADH by enzymatic reactions in the assay. First, the ADP generated by the ATPase is regenerated to ATP by pyruvate kinase (PK). PK catalyzes the transition of phosphoenolpyruvate (PEP) to pyruvate in parallel. Subsequently, pyruvate is reduced to lactate by lactate dehydrogenase (LDH), which catalyzes the oxidation of NADH in parallel. Thus, the decrease in ATP concentration is directly correlated to the decrease in NADH concentration, which is followed by change to the intrinsic fluorescence of NADH. As long as PEP is available in the reaction system, the ADP concentration remains very low, avoiding inhibition of the ATPase enzyme by its own product. Moreover, the ATP concentration remains nearly constant, yielding linear time courses. The fluorescence is monitored continuously, which allows for easy estimation of the quality of data and helps to filter out potential artifacts (e.g., arising from compound precipitation or thermal changes).

A nicotinamide adenine dinucleotide (NADH)-coupled ATPase assay has been adapted to semihigh throughput screening of small molecule myosin inhibitors. This kinetic assay is run in a 384-well microplate format with total reaction volumes of only 20 &#181;L per well. The platform should be applicable to virtually any ADP producing enzyme.

ATPase enzymes utilize the free energy stored in adenosine triphosphate to catalyze a wide variety of endergonic biochemical processes in vivo that would ...

Screening for Phytoestrogens using a Cell-based Estrogen Receptor  &#946; Reporter Assay

Plants are a source of food for many animals, and&#160;they can produce thousands of chemicals. Some of these compounds affect physiological processes in the vertebrates that consume them, such as endocrine function. Phytoestrogens, the most well studied endocrine-active phytochemicals, directly interact with the hypothalamo-pituitary gonadal axis of the vertebrate endocrine system. Here we present the novel use of a cell-based assay to screen plant extracts for the presence of compounds that have estrogenic biological activity. This assay uses mammalian cells engineered to highly express estrogen receptor beta (ER&#946;) and that have been transfected with a luciferase gene. Exposure to compounds with estrogenic activity results in the cells producing light. This assay is a reliable and simple way to test for biological estrogenic activity. It has several improvements over transient transfection assays, most notably, ease of use, the stability of the cells, and the sensitivity of the assay.

We have optimized a commercially available estrogen receptor &#946; reporter assay for screening human and nonhuman primate foods for estrogenic activity. We validated this assay by showing that the known estrogenic human food soy registers high, while other foods show no activity.

Plants are a source of food for many animals, and&#160;they can produce thousands of chemicals. Some of these compounds affect physiological processes in ...

NMR-Based Fragment Screening in a Minimum Sample but Maximum Automation Mode

Fragment-based screening (FBS) is a well-validated and accepted concept within the drug discovery process both in academia and industry. The greatest advantage of NMR-based fragment screening is its ability not only to detect binders over 7-8 orders of magnitude of affinity but also to monitor purity and chemical quality of the fragments and thus to produce high quality hits and minimal false positives or false negatives. A prerequisite within the FBS is to perform initial and periodic quality control of the fragment library, determining solubility and chemical integrity of the fragments in relevant buffers, and establishing multiple libraries to cover diverse scaffolds to accommodate various macromolecule target classes (proteins/RNA/DNA). Further, an extensive NMR-based screening protocol optimization with respect to sample quantities, speed of acquisition and analysis at the level of biological construct/fragment-space, in condition-space (buffer, additives, ions, pH, and temperature) and in ligand-space (ligand analogues, ligand concentration) is required. At least in academia, these screening efforts have so far been undertaken manually in a very limited fashion, leading to limited availability of screening infrastructure not only in the drug development process but also in the context of chemical probe development. In order to meet the requirements economically, advanced workflows are presented. They take advantage of the latest state-of-the-art advanced hardware, with which the liquid sample collection can be filled in a temperature-controlled fashion into the NMR-tubes in an automated manner. 1H/19F NMR ligand-based spectra are then collected at a given temperature. High-throughput sample changer (HT sample changer) can handle more than 500 samples in temperature-controlled blocks. This together with advanced software tools speeds up data acquisition and analysis. Further, application of screening routines on protein and RNA samples are described to make aware of the established protocols for a broad user base in biomacromolecular research.

Fragment-based screening by NMR is a robust method to rapidly identify small molecule binders to biomacromolecules (DNA, RNA, or proteins). Protocols describing automation-based sample preparation, NMR experiments &#38; acquisition conditions, and analysis workflows are presented. The technique allows for optimal exploitation of both 1H and 19F NMR-active nuclei for detection.

Fragment-based screening (FBS) is a well-validated and accepted concept within the drug discovery process both in academia and industry. The greatest ...