This work was supported by a grant from the Packard Center for ALS Research at Johns Hopkins (A.D.G.), an NIH Director&#x2019;s New Innovator Award 1DP2OD004417-01 (A.D.G), NIH R01 NS065317 (A.D.G.), the Rita Allen Foundation Scholar Award. A.D.G. is a Pew Scholar in the Biomedical Sciences, supported by The Pew Charitable Trusts.

1.	Preparations for yeast transformation 
This protocol is designed for ten 96-well plates but can be scaled up or down accordingly. We have found that this protocol does not work well for more than twenty 96-well plates per round of transformation. The entire transformation procedure (from step I.3) will take approximately eight hours.
<ol>
<li>Aliquot 5-10&mu;L of plasmid DNA (100 ng/&mu;l) from the Yeast FLEXGene ORF library into each well of a round-bottom 96-well plate with Biorobot RapidPlate liquid handler. Place uncovered 96-well plates in clean bench fume hood overnight to dry. We have found similar transformation efficiencies with CEN and 2&mu; yeast plasmids.</li>
<li>Inoculate 200mL of yeast peptone dextrose (YPD) media (10g/L yeast extract, 20g/L peptone, 20g/L glucose) with query strain in a 500mL baffled Erlenmeyer flask. Incubate overnight at 30&deg;C with shaking (200 rpm). If required, selective media can also be used for these starter cultures.</li>
<li>The following morning, dilute the query strain to OD600=0.1 in 2L of YPD. Shake for 4-6 hours at 30&deg;C (200 rpm) until the culture reaches OD600=0.8-1.0. For optimal growth, grow up two 1L cultures in separate 2.8 L baffled flasks. If required, selective media can also be used instead of YPD.</li>
</ol>
2. Yeast transformation
<ol>
<li>Harvest cells by centrifugation. Fill four disposable 225mL conical tubes with yeast culture and spin at 3000rpm (&tilde;1800 x g) for 5 minutes in tabletop centrifuge (Eppendorf 5810R). Pour off supernatant and repeat until all cells are harvested.</li>
<li>Wash cells in 200mL of autoclaved distilled H2O. Resuspend cell pellet by shaking or vortexing. Combine cells in one 225mL conical tube. Spin at 3000rpm for 5 minutes. Remove supernatant.</li>
<li>Prepare 0.1MLiOAc/1XTE solution (0.1M LiOAc, 10mM Tris, 1mM EDTA, pH 8 in autoclaved distilled water). Wash cells in 100mL 0.1MLiOAc/1XTE. Spin at 3000rpm for 5 minutes. Remove supernatant.</li>
<li>Resuspend cell pellet in 70mL 0.1M LiOAc/1xTE. Shake and/or vortex to ensure pellet is completely resuspended.</li>
<li>Incubate with shaking at 30&deg;C for 30 minutes (200 rpm).</li>
<li>Add &beta;-mercaptoethanol to 0.1M. Incubate with shaking at 30&deg;C for 30 minutes (200 rpm). Note: This step can be omitted if using yeast strains that are sensitive to &beta;-mercaptoethanol. We have found that this step is not essential for successful transformation, however it does improve transformation efficiency.</li>
<li>Boil 2mL of sonicated salmon sperm DNA (10mg/mL) for 15 minutes, and then chill on ice.</li>
<li>Add 2mL of boiled salmon sperm DNA to cell mixture. Caution: A precipitate may form upon addition of the salmon sperm DNA to the cell mixture. Using a pipetman and 200 &mu;l tip, carefully remove any precipitate that forms because this may interfere with downstream pipetting.</li>
<li>Aliquot 50&mu;L of cell mixture to each well of the 96-well plate using the BioRobot Rapidplate (can also use multi-channel pipette). Do not mix.</li>
<li>Incubate at room temperature for 30 minutes without shaking.</li>
<li>Prepare 200mL of 40%PEG-3350/10%DMSO/0.1M LiOAc (160mL of 50% PEG-3350, 20mL DMSO, 20mL 1M LiOAc). Prepare solution immediately before use.</li>
<li>Add 125&mu;L of PEG/LioAc/DMSO solution to each well. Mix by aspirating and dispensing cell suspension eight times with RapidPlate.</li>
<li>Incubate at room temperature for 30 minutes without shaking.</li>
<li>Heat shock the cells at 42&deg;C for 15 minutes in a dry incubator. Do not stack plates. Note: We have found that this heat shock step is not essential for successful transformation. For certain yeast strains (for example, temperature sensitive mutants), heat shock is deleterious. We have previously reduced the heat shock time to one minute and have been able to successfully transform a yeast strain harboring a ypt1 temperature sensitive mutation using this protocol.</li>
<li>Spin plates at 2500rpm (&tilde;1100 x g) for 5 minutes, using centrifuge adapters to accommodate 96-well plates. Remove PEG solution by inverting plates over waste bucket. Blot inverted plate on paper towel to remove residual liquid (cells will remain on bottom of wells).</li>
<li>Rinse cells by adding 200&mu;L of minimal media (e.g. SD/-Ura) to each well with RapidPlate.</li>
<li>Spin plates at 2500rpm for 5 minutes and remove supernatant by inverting over waste bucket and blotting on paper towels.</li>
<li>Add 200&mu;L of minimal media (e.g. SD/-Ura) to each well with RapidPlate.</li>
<li>Incubate at 30&deg;C for 2 days without shaking. After 2 days, small colonies of cells should begin to form at the bottom of each successfully transformed well.</li>
</ol>
3. Spotting assay
<ol>
<li>Dispense 200&mu;L of raffinose based minimal media (e.g. SRaf/-Ura) into each well of a new flat-bottom 96-well plate.</li>
<li>Mix each well of transformation plate by aspirating and dispensing cell suspension eight times with Rapidplate.</li>
<li>Inoculate SRaf plates with 5&mu;L of cell mixture from transformation plate.</li>
<li>Incubate at 30&deg;C for one day. Small colonies should be present at the bottom of each well after one day.</li>
<li>Spot colonies on SD/-Ura and SGal/-Ura plates in hood. Sterilize 96-bolt replicator (frogger) by flaming. Mix colonies with frogger before spotting on selective media plates. After spotting, allow plates to dry in hood for 5-10 minutes.</li>
<li>Incubate at 30&deg;C for 2-3 days.</li>
</ol>

Photograph plates with digital camera, and visually compare growth of colonies on SGal/-Ura plates to find colonies in which query strain toxicity is enhanced (slower growth/less dense colonies) or suppressed (faster growth/more dense colonies). 
4. Representative results:
<img src="/files/ftp_upload/2836/2836fig1.jpg" alt="Figure 1"/> 
Figure 1. Yeast plasmid overexpression screen to identify suppressors and enhancers of TDP-43 toxicity. TDP-43 is a human protein that has been implicated in the pathogenesis of amyotrophic lateral sclerosis (Lou Gehrig&#x2019;s disease). Cytoplasmic aggregates of TDP-43 accumulate in the brain and spinal cord neurons of ALS patients 17. Expressing TDP-43 in yeast cells results in aggregation and cytotoxicity 18. We have used this model system to define mechanisms of TDP-43 toxicity 19,20. Shown are repesentative examples of plates from our yeast TDP-43 toxicity modifier screen. These plates display colonies with an integrated galactose-inducible TDP-43 plasmid and also transformed with plasmids from the FLEXGene ORF expression library. The plate on the left contains glucose, which represses expression of TDP-43 or the FLEXGene plasmids. The plate on the right contains galactose, which induces the expression of TDP-43 and the ORFs in the FLEXGene plasmids. The green arrowhead indicates a colony transformed with a plasmid that suppresses the toxicity of TDP-43. The red arrowhead indicates a colony transformed with a plasmid that enhances the toxicity of TDP-43.

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No conflicts of interest declared.

Here we present a protocol to perform a high-throughput plasmid overexpression screen in yeast. This approach allows for the rapid and unbiased screening for genetic modifiers of many different cellular phenotypes. Using this approach, a researcher can screen a significant portion of the yeast genome in a matter of weeks. This unbiased approach also allows for the identification of modifiers, which may not have been predicted based on previous findings. We have used this approach to identify modifiers of toxicity assoc...

<table border="1">
	<tbody>
 	<tr>
 	<th>Name of reagent</th>
 <th>Company</th>
 <th>Catalog number</th>
 </tr>
 <tr>
 	<td>BioRobot RapidPlate</td>
 <td>Qiagen</td>
 <td>9000490</td>
 </tr>
 <tr>
 	<td>96 bolt replicator (frogger)</td>
 <td>V&amp;P Scientific</td>
 <td>VP404</td>
 </tr>
 <tr>
 	<td>FLEXGene ORF Library</td>
 <td>Institute of Proteomics, Harvard Medical School</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 	<td>Tabletop centrifuge</td>
 <td>Eppendorf</td>
 <td>5810R</td>
 </tr>
 <tr>
 	<td>500mL baffled flask</td>
 <td>Bellco</td>
 <td>2543-00500</td>
 </tr>
 <tr>
 	<td>2.8L triple-baffled Fernbach flask</td>
 <td>Bellco</td>
 <td>2551-02800</td>
 </tr>
 <tr>
 	<td>100&mu;L Rapidplate pipette tips</td>
 <td>Axygen</td>
 <td>ZT-100-R-S</td>
 </tr>
 <tr>
 	<td>200&mu;L Rapidplate pipette tips</td>
 <td>Axygen</td>
 <td>ZT-200-R-S</td>
 </tr>
 </tbody>
</table>

high-throughput yeast plasmid overexpression screen

The budding yeast, Saccharomyces cerevisiae, is a powerful model system for defining fundamental mechanisms of many important cellular processes, including those with direct relevance to human disease. Because of its short generation time and well-characterized genome, a major experimental advantage of the yeast model system is the ability to perform genetic screens to identify genes and pathways that are involved in a given process. Over the last thirty years such genetic screens have been used to elucidate the cell cycle, secretory pathway, and many more highly conserved aspects of eukaryotic cell biology 1-5. In the last few years, several genomewide libraries of yeast strains and plasmids have been generated 6-10. These collections now allow for the systematic interrogation of gene function using gain- and loss-of-function approaches 11-16. Here we provide a detailed protocol for the use of a high-throughput yeast transformation protocol with a liquid handling robot to perform a plasmid overexpression screen, using an arrayed library of 5,500 yeast plasmids. We have been using these screens to identify genetic modifiers of toxicity associated with the accumulation of aggregation-prone human neurodegenerative disease proteins. The methods presented here are readily adaptable to the study of other cellular phenotypes of interest.

Watch this Scientific Journal Video about High-throughput Yeast Plasmid Overexpression Screen at JoVE.com

High-throughput Yeast Plasmid Overexpression Screen

Here we describe a plasmid overexpression screen in Saccharomyces cerevisiae, using an arrayed plasmid library and a high-throughput yeast transformation protocol with a liquid handling robot.

The budding yeast, Saccharomyces cerevisiae, is a powerful model system for defining fundamental mechanisms of many important cellular processes, ...

high-throughput-yeast-plasmid-overexpression-screen

Research

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Biology

16.3K visualizações.  University of Pennsylvania School of Medicine. Aqui nós descrevemos uma tela superexpressão plasmídeo em Saccharomyces cerevisiae, Usando uma biblioteca vestiu plasmídeo e uma alta taxa de transferência de protocolo de transformação de levedura com um robô para manipulação de líquidos.

Vídeo: High-throughput Yeast Plasmid Overexpression Screen

A High Throughput Screen for Biomining Cellulase Activity from Metagenomic Libraries

Cellulose, the most abundant source of organic carbon on the planet, has wide-ranging industrial applications with increasing emphasis on biofuel production 1. Chemical methods to modify or degrade cellulose typically require strong acids and high temperatures. As such, enzymatic methods have become prominent in the bioconversion process. While the identification of active cellulases from bacterial and fungal isolates has been somewhat effective, the vast majority of microbes in nature resist laboratory cultivation. Environmental genomic, also known as metagenomic, screening approaches have great promise in bridging the cultivation gap in the search for novel bioconversion enzymes. Metagenomic screening approaches have successfully recovered novel cellulases from environments as varied as soils 2, buffalo rumen 3 and the termite hind-gut 4 using carboxymethylcellulose (CMC) agar plates stained with congo red dye (based on the method of Teather and Wood 5). However, the CMC method is limited in throughput, is not quantitative and manifests a low signal to noise ratio 6. Other methods have been reported 7,8 but each use an agar plate-based assay, which is undesirable for high-throughput screening of large insert genomic libraries. Here we present a solution-based screen for cellulase activity using a chromogenic dinitrophenol (DNP)-cellobioside substrate 9. Our library was cloned into the pCC1 copy control fosmid to increase assay sensitivity through copy number induction 10. The method uses one-pot chemistry in 384-well microplates with the final readout provided as an absorbance measurement. This readout is quantitative, sensitive and automated with a throughput of up to 100X 384-well plates per day using a liquid handler and plate reader with attached stacking system.

This protocol describes a high throughput screen for cellulolytic activity from a metagenomic library expressed in Escherichia coli. The screen is solution based and highly automated, and uses one-pot chemistry in 384 well microplates with the final readout as an absorbance measurement.

Cellulose, the most abundant source of organic carbon on the planet, has wide-ranging industrial applications with increasing emphasis on biofuel ...

High-throughput Saccharification Assay for Lignocellulosic Materials

Polysaccharides that make up plant lignocellulosic biomass can be broken down to produce a range of sugars that subsequently can be 
used in establishing a biorefinery. These raw materials would constitute a new industrial platform, which is both sustainable and carbon neutral, to replace 
the current dependency on fossil fuel. The recalcitrance to deconstruction observed in lignocellulosic materials is produced by several intrinsic properties 
of plant cell walls. Crystalline cellulose is embedded in matrix polysaccharides such as xylans and arabinoxylans, and the whole structure is encased by the 
phenolic polymer lignin, that is also difficult to digest 1. In order to improve the digestibility of plant materials we need to discover the main bottlenecks 
for the saccharification of cell walls and also screen mutant and breeding populations to evaluate the variability in saccharification 2. These tasks require 
a high throughput approach and here we present an analytical platform that can perform saccharification analysis in a 96-well plate format. This platform has 
been developed to allow the screening of lignocellulose digestibility of large populations from varied plant species. We have scaled down the reaction volumes 
for gentle pretreatment, partial enzymatic hydrolysis and sugar determination, to allow large numbers to be assessed rapidly in an automated system.
This automated platform works with milligram amounts of biomass, performing ball milling under controlled conditions to reduce the plant 
materials to a standardised particle size in a reproducible manner. Once the samples are ground, the automated formatting robot dispenses specified and recorded 
amounts of material into the corresponding wells of 96 deep well plate (Figure 1). Normally, we dispense the same material into 4 wells to have 4 replicates for 
analysis. Once the plates are filled with the plant material in the desired layout, they are manually moved to a liquid handling station (Figure 2). In this 
station the samples are subjected to a mild pretreatment with either dilute acid or alkaline and incubated at temperatures of up to 90&deg;C. The pretreatment solution 
is subsequently removed and the samples are rinsed with buffer to return them to a suitable pH for hydrolysis. The samples are then incubated with an enzyme
mixture for a variable length of time at 50&deg;C. An aliquot is taken from the hydrolyzate and the reducing sugars are automatically determined by the MBTH 
colorimetric method.

A simple, rapid method for determining the saccharification potential of large numbers of plant biomass samples is described. The automated platform for this analysis involves the preparation of the plant biomass for analysis in 96 well plates and the subsequent performance of pretreatment, hydrolysis and quantification of the sugars released.

Polysaccharides that make up plant lignocellulosic biomass can be broken down to produce a range of sugars that subsequently can be 
used in establishing ...

High-throughput Purification of Affinity-tagged Recombinant Proteins

X-ray crystallography is the method of choice for obtaining a detailed view of the structure of proteins. Such studies need to be complemented by further biochemical analyses to obtain detailed insights into structure/function relationships. Advances in oligonucleotide- and gene synthesis technology make large-scale mutagenesis strategies increasingly feasible, including the substitution of target residues by all 19 other amino acids. Gain- or loss-of-function phenotypes then allow systematic conclusions to be drawn, such as the contribution of particular residues to catalytic activity, protein stability and/or protein-protein interaction specificity.
In order to attribute the different phenotypes to the nature of the mutation - rather than to fluctuating experimental conditions - it is vital to purify and analyse the proteins in a controlled and reproducible manner. High-throughput strategies and the automation of manual protocols on robotic liquid-handling platforms have created opportunities to perform such complex molecular biological procedures with little human intervention and minimal error rates1-5.
Here, we present a general method for the purification of His-tagged recombinant proteins in a high-throughput manner. In a recent study, we applied this method to a detailed structure-function investigation of TFIIB, a component of the basal transcription machinery. TFIIB is indispensable for promoter-directed transcription in vitro and is essential for the recruitment of RNA polymerase into a preinitiation complex6-8. TFIIB contains a flexible linker domain that penetrates the active site cleft of RNA polymerase9-11. This linker domain confers two biochemically quantifiable activities on TFIIB, namely (i) the stimulation of the catalytic activity during the 'abortive' stage of transcript initiation, and (ii) an additional contribution to the specific recruitment of RNA polymerase into the preinitiation complex4,5,12 . We exploited the high-throughput purification method to generate single, double and triple substitution and deletions mutations within the TFIIB linker and to subsequently analyse them in functional assays for their stimulation effect on the catalytic activity of RNA polymerase4. Altogether, we generated, purified and analysed 381 mutants - a task which would have been time-consuming and laborious to perform manually. We produced and assayed the proteins in multiplicates which allowed us to appreciate any experimental variations and gave us a clear idea of the reproducibility of our results.
This method serves as a generic protocol for the purification of His-tagged proteins and has been successfully used to purify other recombinant proteins. It is currently optimised for the purification of 24 proteins but can be adapted to purify up to 96 proteins.

We describe a method for the affinity-tagged purification of recombinant proteins using liquid-handling robotics. This method is generally applicable to the small-scale purification of soluble His-tagged proteins in a high-throughput format.

X-ray crystallography is the method of choice for obtaining a detailed view of the structure of proteins. Such studies need to be complemented by further ...

RNA Secondary Structure Prediction Using High-throughput SHAPE

Understanding the function of RNA involved in biological processes requires a thorough knowledge of RNA structure. Toward this end, the methodology dubbed "high-throughput selective 2' hydroxyl acylation analyzed by primer extension", or SHAPE, allows prediction of RNA secondary structure with single nucleotide resolution. This approach utilizes chemical probing agents that preferentially acylate single stranded or flexible regions of RNA in aqueous solution. Sites of chemical modification are detected by reverse transcription of the modified RNA, and the products of this reaction are fractionated by automated capillary electrophoresis (CE). Since reverse transcriptase pauses at those RNA nucleotides modified by the SHAPE reagents, the resulting cDNA library indirectly maps those ribonucleotides that are single stranded in the context of the folded RNA. Using ShapeFinder software, the electropherograms produced by automated CE are processed and converted into nucleotide reactivity tables that are themselves converted into pseudo-energy constraints used in the RNAStructure (v5.3) prediction algorithm. The two-dimensional RNA structures obtained by combining SHAPE probing with in silico RNA secondary structure prediction have been found to be far more accurate than structures obtained using either method alone.

High-throughput selective 2' hydroxyl acylation analyzed by primer extension (SHAPE) utilizes a novel chemical probing technology, reverse transcription, capillary electrophoresis and secondary structure prediction software to determine the structures of RNAs from several hundred to several thousand nucleotides at single nucleotide resolution.

Understanding the function of RNA involved in biological processes requires a thorough knowledge of RNA structure. Toward this end, the methodology dubbed ...

High Throughput Microinjections of Sea Urchin Zygotes

Microinjection into cells and embryos is a common technique that is used to study a wide range of biological processes. In this method a small amount of treatment solution is loaded into a microinjection needle that is used to physically inject individual immobilized cells or embryos. Despite the need for initial training to perform this procedure for high-throughput delivery, microinjection offers maximum efficiency and reproducible delivery of a wide variety of treatment solutions (including complex mixtures of samples) into cells, eggs or embryos. Applications to microinjections include delivery of DNA constructs, mRNAs, recombinant proteins, gain of function, and loss of function reagents. Fluorescent or colorimetric dye is added to the injected solution to enable instant visualization of efficient delivery as well as a tool for reliable normalization of the amount of the delivered solution. The described method enables microinjection of 100-400 sea urchin zygotes within 10-15 min.

Microinjection is a common technique used to deliver DNA constructs, mRNAs, morpholino antisense oligonucleotides or other treatments into eggs, embryos, and cells of various species.

Microinjection into cells and embryos is a common technique that is used to study a wide range of biological processes. In this method a small amount of ...

High-throughput Titration of Luciferase-expressing Recombinant Viruses

Standard plaque assays to determine infectious viral titers can be time consuming, are not amenable to a high volume of samples, and cannot be done with viruses that do not form plaques. As an alternative to plaque assays, we have developed a high-throughput titration method that allows for the simultaneous titration of a high volume of samples in a single day. This approach involves infection of the samples with a Firefly luciferase tagged virus, transfer of the infected samples onto an appropriate permissive cell line, subsequent addition of luciferin, reading of plates in order to obtain luminescence readings, and finally the conversion from luminescence to viral titers. The assessment of cytotoxicity using a metabolic viability dye can be easily incorporated in the workflow in parallel and provide valuable information in the context of a drug screen. This technique provides a reliable, high-throughput method to determine viral titers as an alternative to a standard plaque assay.

This article presents a high-throughput luciferase expression-based method of titrating various RNA and DNA viruses using automated and manual liquid handlers.

Standard plaque assays to determine infectious viral titers can be time consuming, are not amenable to a high volume of samples, and cannot be done with ...

A Manual Small Molecule Screen Approaching High-throughput Using Zebrafish Embryos

Zebrafish have become a widely used model organism to investigate the mechanisms that underlie developmental biology and to study human disease pathology due to their considerable degree of genetic conservation with humans. Chemical genetics entails testing the effect that small molecules have on a biological process and is becoming a popular translational research method to identify therapeutic compounds. Zebrafish are specifically appealing to use for chemical genetics because of their ability to produce large clutches of transparent embryos, which are externally fertilized. Furthermore, zebrafish embryos can be easily drug treated by the simple addition of a compound to the embryo media. Using whole-mount in situ hybridization (WISH), mRNA expression can be clearly visualized within zebrafish embryos. Together, using chemical genetics and WISH, the zebrafish becomes a potent whole organism context in which to determine the cellular and physiological effects of small molecules. Innovative advances have been made in technologies that utilize machine-based screening procedures, however for many labs such options are not accessible or remain cost-prohibitive. The protocol described here explains how to execute a manual high-throughput chemical genetic screen that requires basic resources and can be accomplished by a single individual or small team in an efficient period of time. Thus, this protocol provides a feasible strategy that can be implemented by research groups to perform chemical genetics in zebrafish, which can be useful for gaining fundamental insights into developmental processes, disease mechanisms, and to identify novel compounds and signaling pathways that have medically relevant applications.

The zebrafish is an excellent experimental organism to study vertebrate developmental processes and model human disease. Here, we describe a protocol on how to perform a manual high-throughput chemical screen in zebrafish embryos with a whole-mount in situ hybridization (WISH) read-out.

Zebrafish have become a widely used model organism to investigate the mechanisms that underlie developmental biology and to study human disease pathology ...

Recovery of Adult Zebrafish Hearts for High-throughput Applications

Use of the zebrafish model system for studying development, regeneration, and disease is expanding toward use of adult hearts for cell dissociation and purification of RNA, DNA, and proteins. All of these applications demand the rapid recovery of significant numbers of zebrafish hearts to avoid gene regulatory, metabolic, and other changes that begin after death. Adult zebrafish hearts are also required for studying heart structure for a variety of mutants and for studying heart regeneration. However, the traditional zebrafish heart dissection is slow and difficult and requires specialized tools, making large-scale dissection of adult zebrafish hearts tedious. Traditional methods also harbor the risk of damaging the heart during the dissection. Here, we describe a method for dissection of adult zebrafish hearts that is fast, reproducible, and preserves heart architecture. Furthermore, this method does not require specialized tools, is painless for the zebrafish, can be performed on fresh or fixed specimens, and can be performed on zebrafish as young as one month old. The approach described expands the use of adult zebrafish for cardiovascular research.

Use of zebrafish for cardiovascular research is expanding towards research on adult hearts. For these applications, quick and simple isolation of cardiac tissues is key to avoid post-mortem changes and to obtain an adequate number of samples. Here, we describe a fast and reproducible method for dissecting adult zebrafish hearts.

Use of the zebrafish model system for studying development, regeneration, and disease is expanding toward use of adult hearts for cell dissociation and ...

High-throughput Screening for Chemical Modulators of Post-transcriptionally Regulated Genes

Both transcriptional and post-transcriptional regulation have a profound impact on genes expression. However, commonly adopted cell-based screening assays focus on transcriptional regulation, being essentially aimed at the identification of promoter-targeting molecules. As a result, post-transcriptional mechanisms are largely uncovered by gene expression targeted drug development. Here we describe a cell-based assay aimed at investigating the role of the 3&#39; untranslated region (3&#8217; UTR) in the modulation of the fate of its mRNA, and at identifying compounds able to modify it. The assay is based on the use of a luciferase reporter construct containing the 3&#8217; UTR of a gene of interest stably integrated into a disease-relevant cell line. The protocol is divided into two parts, with the initial focus on the primary screening aimed at the identification of molecules affecting luciferase activity after 24 hr of treatment. The second part of the protocol describes the counter-screening necessary to discriminate compounds modulating luciferase activity specifically through the 3&#8217; UTR. In addition to the detailed protocol and representative results, we provide important considerations about the assay development and the validation of the hit(s) on the endogenous target. The described cell-based reporter gene assay will allow scientists to identify molecules modulating protein levels via post-transcriptional mechanisms dependent on a 3&#8217; UTR.

Here we describe a cell-based reporter gene assay as a valuable tool to screen chemical libraries for compounds modulating post-transcriptional control mechanisms exerted through 3&#8217; UTR.

Both transcriptional and post-transcriptional regulation have a profound impact on genes expression. However, commonly adopted cell-based screening assays ...

High Throughput Danio Rerio Energy Expenditure Assay

Zebrafish are an important model organism with inherent advantages that have the potential to make zebrafish a widely applied model for the study of energy homeostasis and obesity. The small size of zebrafish allows for assays on embryos to be conducted in a 96- or 384-well plate format, Morpholino and CRISPR based technologies promote ease of genetic manipulation, and drug treatment by bath application is viable. Moreover, zebrafish are ideal for forward genetic screens allowing for novel gene discovery. Given the relative novelty of zebrafish as a model for obesity, it is necessary to develop tools that fully exploit these benefits. Herein, we describe a method to measure energy expenditure in thousands of embryonic zebrafish simultaneously. We have developed a whole animal microplate platform in which we use 96-well plates to isolate individual fish and we assess cumulative NADH2 production using the commercially available cell culture viability reagent alamarBlue. In poikilotherms the relationship between NADH2 production and energy expenditure is tightly linked. This energy expenditure assay creates the potential to rapidly screen pharmacological or genetic manipulations that directly alter energy expenditure or alter the response to an applied drug (e.g. insulin sensitizers).

High Throughput Danio Rerio Energy Expenditure Assay

Zebrafish are an important model organism for the study of energy homeostasis. By utilizing a NADH2 sensitive redox indicator, alamar Blue, we have developed an assay that measures the metabolic rate of zebrafish larvae in a 96 well plate format and can be applied to drug or gene discovery.

Zebrafish are an important model organism with inherent advantages that have the potential to make zebrafish a widely applied model for the study of ...