Name: rapid identification of chemical genetic interactions in saccharomyces cerevisiae
Uploaded: 2015-04-05T14:00:00
Description: Watch this Scientific Journal Video about Rapid Identification of Chemical Genetic Interactions in Saccharomyces cerevisiae at JoVE.com

Research in the CJN lab is supported by operating grants from NSERC, the Canadian Cancer Society Research Institute (CCSRI), and the Canadian Breast Cancer Foundation (BC-Yukon Branch).

NOTE: The general workflow of this procedure is outlined in Figure 2.
1. Determination of Growth-inhibitory Dose
<ol>
	<li>Preparation of yeast overnight culture 
	NOTE: The yeast-extract-peptone-dextrose growth media (YEPD) used in this protocol is a standard recipe13.
	<ol>
		<li>Streak out BY4741 (MATahis3&#916;1 leu2&#916;0 met15&#916;0 ura3&#916;0) cells on a YEPD agar plate and incubate for 48 hr at 30&#160;&#176;C&#160;or unt...

<ol>
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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=A+comprehensive+strategy+enabling+high-resolution+functional+analysis+of+the+yeast+genome.">A comprehensive strategy enabling high-resolution functional analysis of the yeast genome.</a> Nat Methods. 5, 711-718 (2008).</li><li>Li, 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=Systematic+exploration+of+essential+yeast+gene+function+with+temperature-sensitive+mutants.">Systematic exploration of essential yeast gene function with temperature-sensitive mutants.</a> Nat Biotechnol. 29, 361-367 (2011).</li><li>Costanzo, 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=The+genetic+landscape+of+a+cell.">The genetic landscape of a cell.</a> Science. 327, 425-431 (2010).</li><li>Parsons, A. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integration+of+chemical-genetic+and+genetic+interaction+data+links+bioactive+compounds+to+cellular+target+pathways.">Integration of chemical-genetic and genetic interaction data links bioactive compounds to cellular target pathways.</a> Nat Biotechnol. 22, 62-69 (2004).</li><li>Parsons, A. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploring+the+mode-of-action+of+bioactive+compounds+by+chemical-genetic+profiling+in+yeast.">Exploring the mode-of-action of bioactive compounds by chemical-genetic profiling in yeast.</a> Cell. 126, 611-625 (2006).</li><li>Hillenmeyer, M. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+chemical+genomic+portrait+of+yeast:+uncovering+a+phenotype+for+all+genes.">The chemical genomic portrait of yeast: uncovering a phenotype for all genes.</a> Science. 320, 362-365 (2008).</li><li>Hillenmeyer, M. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systematic+analysis+of+genome-wide+fitness+data+in+yeast+reveals+novel+gene+function+and+drug+action.">Systematic analysis of genome-wide fitness data in yeast reveals novel gene function and drug action.</a> Genome Biol. 11, R30 (2010).</li><li>Smith, A. 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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical-genetic+identification+of+the+biochemical+targets+of+polyalkyl+guanidinium+biocides.">Chemical-genetic identification of the biochemical targets of polyalkyl guanidinium biocides.</a> Organic &amp; Biomolecular Chemistry. 11, 4359-4366 (2013).</li><li>Alamgir, M., Erukova, V., Jessulat, M., Azizi, A., Golshani, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical-genetic+profile+analysis+of+five+inhibitory+compounds+in+yeast.">Chemical-genetic profile analysis of five inhibitory compounds in yeast.</a> BMC Chem Biol. 10 (6), (2010).</li><li>Amberg, D. C., Burke, D., Strathern, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Cold Spring Harbor Laboratory. Methods In Yeast Genetics: A Cold Spring Harbor Laboratory Course Manual. , (2005).</li><li>Baryshnikova, 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=Synthetic+genetic+array+(SGA)+analysis+in+Saccharomyces+cerevisiae+and+Schizosaccharomyces+pombe.">Synthetic genetic array (SGA) analysis in Saccharomyces cerevisiae and Schizosaccharomyces pombe.</a> Methods Enzymol. 470, 145-179 (2010).</li><li>Young, B. P., Loewen, C. 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J., Rothstein, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ScreenMill:+a+freely+available+software+suite+for+growth+measurement,+analysis+and+visualization+of+high-throughput+screen+data.">ScreenMill: a freely available software suite for growth measurement, analysis and visualization of high-throughput screen data.</a> BMC Bioinformatics. 11, 353 (2010).</li><li>Longley, D. B., Harkin, D. P., Johnston, P. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=5-fluorouracil:+mechanisms+of+action+and+clinical+strategies.">5-fluorouracil: mechanisms of action and clinical strategies.</a> Nat Rev Cancer. 3, 330-338 (2003).</li><li>Lum, P. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Discovering+modes+of+action+for+therapeutic+compounds+using+a+genome-wide+screen+of+yeast+heterozygotes.">Discovering modes of action for therapeutic compounds using a genome-wide screen of yeast heterozygotes.</a> Cell. 116, 121-137 (2004).</li><li>Toussaint, M., Conconi, A. <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+and+sensitive+assay+to+measure+yeast+cell+growth:+a+bench+protocol+for+testing+genotoxic+agents.">High-throughput and sensitive assay to measure yeast cell growth: a bench protocol for testing genotoxic agents.</a> Nat Protoc. 1, 1922-1928 (2006).</li><li>Robinson, M. D., Grigull, J., Mohammad, N., Hughes, T. 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Outlined here is an approach for generating chemical-genetic interaction profiles. The method is simple: by comparing colony sizes of each strain in comprehensive gene deletion collections in the presence and absence of a chemical, all genes needed to tolerate a chemical insult are identified. Annotation enrichment analysis of the resulting list of sensitive strains can then be used to provide insight into a chemicals mode of action. While this protocol has been optimized for budding yeast, it can also be adapted for use...

The genetic tools and resources available in the model organism Saccharomyces cerevisiae have enabled large-scale functional genomics studies that collectively provide new insight into how genes function as networks to fulfill the requirements of biological systems. The cornerstone of these tools was the collaborative creation of a complete set of non-essential gene deletions of all open reading frames in yeast1,2. A striking observation was that only ~20% of yeast genes are required for viability when grown as haploids under standard laboratory conditions. This highlights&#160;the ability of a cell to buffer against genomic perturbations through the utilization of alternative biological pathways. Genetic mutants that are viable individually, but lethal in combination, signal connected or convergent parallel biological pathways and form genetic interaction networks that describe biological function. With the development of conditional&#160;temperature-sensitive and hypomorphic alleles of essential genes the technology has not been limited to the study of non-essential genes3,4. This concept has been applied at a genomic scale producing an unbiased genetic interaction map illustrating how genes involved in similar cellular processes cluster together5.
Chemical perturbations of genetic networks mimic gene deletions (Figure 1)6. Querying growth-inhibitory compounds against a high-density array of deletion strains for hypersensitivity identifies a chemical-genetic interaction profile, i.e. a list of genes that is required to tolerate chemical stress. Like genetic interactions, large-scale screens of chemical libraries have shown that compounds with a similar mode of action cluster together7. Therefore, by establishing the chemical-genetic interaction profile of a compound the mode of action may be inferred by comparing it with large-scale synthetic genetic and chemical genetic interaction datasets8,9.
Large-scale chemical-genetic screens, where scores of compounds are interrogated, have been performed by barcode competition assays. In this approach, the pooled collection of deletion strains is grown en masse for several generations in a small volume of media containing a chemical. Since each deletion mutant harbors a unique genetic barcode, the viability/growth of individual mutants within the pool of deletion strains is tracked by microarray or high-throughput sequencing10.
Inferring fitness by monitoring colony size of physically arrayed mutants grown on solid agar containing a bioactive compound is also an effective method to identify chemical-genetic interactions11,12. This approach provides a cost-effective alternative to competition-based screening and is well suited for assaying small libraries of chemicals. Outlined here is a simple methodology for producing a list of chemical-genetic interactions in S. cerevisiae that does not rely on molecular biology manipulations or infrastructure. It requires only a yeast deletion collection, a robotic or manual pinning apparatus, and freely available image analysis software.

<table border="0" cellpadding="0" cellspacing="0" width="987">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Name of Material/ Equipment&#160;</td>
			<td style="width:161px;">Company&#160;</td>
			<td style="width:156px;">Catalog Number&#160;</td>
			<td style="width:457px;">Comments/Description&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:213px;">Yeast Extract</td>
			<td style="width:161px;">BioBasic</td>
			<td>G0961</td>
			<td style="width:457px;">For YEPD liquid/solid media add to 1% final concentration (w/v)</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:213px;">Tyrptone Powder</td>
			<td style="width:161px;">BD Biosciences</td>
			<td>211820</td>
			<td style="width:457px;">For YEPD liquid/solid media add to 2% final concentration (w/v)</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:213px;">Dextrose</td>
			<td style="width:161px;">Anachemia</td>
			<td style="width:156px;">31096-380</td>
			<td style="width:457px;">For YEPD liquid/solid media add to 2% final concentration (w/v) - Do not autoclave. Prepare 20% stock solution, filter sterilize, and add to media after autoclaving.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">Agar A</td>
			<td style="width:161px;">Bio Basic</td>
			<td>FB0010</td>
			<td style="width:457px;">For YEPD solid media add to 2% final concentration (w/v)</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:213px;">G418</td>
			<td style="width:161px;">A.G. Scientific Inc.</td>
			<td style="width:156px;">G-1033</td>
			<td style="width:457px;">Prepare 1000x stock at 200mg/ml in dH2O and filter sterilize.&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">12 well plate</td>
			<td>Greiner Bio One</td>
			<td>655180</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">5ml culture tubes</td>
			<td>Evergreen Scientific</td>
			<td>222-2376-080</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:213px;">10cm Petri Dish</td>
			<td style="width:161px;">VWR</td>
			<td>25384-302</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ROTOR HDA</td>
			<td>Singer Instruments&#160;</td>
			<td>ROT-001</td>
			<td>high-throughput microbial array pinning robot</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PLUSPLATE&#169; Petri Dish</td>
			<td>Singer Instruments&#160;</td>
			<td>PLU-001</td>
			<td>Box of 200 dishes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">384 Short-Pin RePad</td>
			<td>Singer Instruments&#160;</td>
			<td>RP-MP-384</td>
			<td>Box of 1000 pads</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1536 Short-Pin RePad</td>
			<td>Singer Instruments&#160;</td>
			<td>RP-MP-1536</td>
			<td>Box of 1000 pads</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Alternative Pinning Tools:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fully Automated Robtic Systems</td>
			<td>S&#38;P robotics</td>
			<td>http://www.sprobotics.com</td>
			<td>Several automated colony handling robitic and imagining systems available.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Manual Pinning Tools</td>
			<td>V&#38;P Scientific</td>
			<td>http://www.vp-scientific.com</td>
			<td>Handheld replication tools and accessories.&#160;</td>
		</tr>
	</tbody>
</table>

rapid identification of chemical genetic interactions in saccharomyces cerevisiae

Determining the mode of action of bioactive chemicals is of interest to a broad range of academic, pharmaceutical, and industrial scientists. Saccharomyces cerevisiae, or budding yeast, is a model eukaryote for which a complete collection of ~6,000 gene deletion mutants and hypomorphic essential gene mutants are commercially available. These collections of mutants can be used to systematically detect chemical-gene interactions, i.e. genes necessary to tolerate a chemical. This information, in turn, reports on the likely mode of action of the compound. Here we describe a protocol for the rapid identification of chemical-genetic interactions in budding yeast. We demonstrate the method using the chemotherapeutic agent 5-fluorouracil (5-FU), which has a well-defined mechanism of action. Our results show that the nuclear TRAMP RNA exosome and DNA repair enzymes are needed for proliferation in the presence of 5-FU, which is consistent with previous microarray based bar-coding chemical genetic approaches and the knowledge that 5-FU adversely affects both RNA and DNA metabolism. The required validation protocols of these high-throughput screens are also described.

As a validation of this approach we performed a representative chemical genetic interaction screen of the chemotherapeutic agent 5-fluorouracil (5-FU) following the above outlined protocol. 5-FU is known to disrupt thymidylate synthase as well as DNA and RNA metabolism18. The chemical genetic interactions of 5-FU are well studied and have been investigated by yeast barcode microarray techniques using both heterozygous and homozygous deletion collections8,19. Here we show that similar results can be ...

Watch this Scientific Journal Video about Rapid Identification of Chemical Genetic Interactions in Saccharomyces cerevisiae at JoVE.com

Rapid Identification of Chemical Genetic Interactions in Saccharomyces cerevisiae

Here we present a cost-effective method for defining chemical-genetic interactions in budding yeast. The approach is built on fundamental techniques in yeast molecular biology and is well suited for the mechanistic interrogation of small to medium collections of chemicals and other media environments.

Rapid Identification of Chemical Genetic Interactions in Saccharomyces cerevisiae

Determining the mode of action of bioactive chemicals is of interest to a broad range of academic, pharmaceutical, and industrial scientists. ...

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Research

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Biology

Dissection of Saccharomyces Cerevisiae Asci

Yeast is a highly tractable model system that is used to study many different cellular processes. The common laboratory strain Saccharomyces cerevisiae exists in either a haploid or diploid state. The ability to combine alleles from two haploids and the ability to introduce modifications to the genome requires the production and dissection of asci. Asci production from haploid cells begins with the mating of two yeast haploid strains with compatible mating types to produce a diploid strain. This can be accomplished in a number of ways either on solid medium or in liquid. It is advantageous to select for the diploids in medium that selectively promotes their growth compared to either of the haploid strains. The diploids are then allowed to sporulate on nutrient-poor medium to form asci, a bundle of four haploid daughter cells resulting from meiotic reproduction of the diploid. A mixture of vegetative cells and asci is then treated with the enzyme zymolyase to digest away the membrane sac surrounding the ascospores of the asci. Using micromanipulation with a microneedle under a dissection microscope one can pick up individual asci and separate and relocate the four ascopores. Dissected asci are grown for several days and tested for the markers or alleles of interest by replica plating onto appropriate selective media.

Dissection of Saccharomyces Cerevisiae Asci

Micromanipulation of yeast cells is needed for meiotic genetic analysis or to select diploid zygotes. These micromanipulations are carried out using the microneedle of a dissection microscope. The microneedle is used to relocate cells and is controlled by a micromanipulator which are available with various degrees of automation.

Yeast is a highly tractable model system that is used to study many different cellular processes. The common laboratory strain Saccharomyces cerevisiae ...

Identification of protein complexes with quantitative proteomics in S. cerevisiae

Lipids are the building blocks of cellular membranes that function as barriers and in compartmentalization of cellular processes, and recently, as important intracellular signalling molecules. However, unlike proteins, lipids are small hydrophobic molecules that traffic primarily by poorly described nonvesicular routes, which are hypothesized to occur at membrane contact sites (MCSs). MCSs are regions where the endoplasmic reticulum (ER) makes direct physical contact with a partnering organelle, e.g., plasma membrane (PM). The ER portion of ER-PM MCSs is enriched in lipid-synthesizing enzymes, suggesting that lipid synthesis is directed to these sites and implying that MCSs are important for lipid traffic. Yeast is an ideal model to study ER-PM MCSs because of their abundance, with over 1000 contacts per cell, and their conserved nature in all eukaryotes. Uncovering the proteins that constitute MCSs is critical to understanding how lipids traffic is accomplished in cells, and how they act as signaling molecules. We have found that an ER called Scs2p localize to ER-PM MCSs and is important for their formation. We are focused on uncovering the molecular partners of Scs2p. Identification of protein complexes traditionally relies on first resolving purified protein samples by gel electrophoresis, followed by in-gel digestion of protein bands and analysis of peptides by mass spectrometry. This often limits the study to a small subset of proteins. Also, protein complexes are exposed to denaturing or non-physiological conditions during the procedure. To circumvent these problems, we have implemented a large-scale quantitative proteomics technique to extract unbiased and quantified data. We use stable isotope labeling with amino acids in cell culture (SILAC) to incorporate staple isotope nuclei in proteins in an untagged control strain. Equal volumes of tagged culture and untagged, SILAC-labeled culture are mixed together and lysed by grinding in liquid nitrogen. We then carry out an affinity purification procedure to pull down protein complexes. Finally, we precipitate the protein sample, which is ready for analysis by high-performance liquid chromatography/ tandem mass spectrometry. Most importantly, proteins in the control strain are labeled by the heavy isotope and will produce a mass/ charge shift that can be quantified against the unlabeled proteins in the bait strain. Therefore, contaminants, or unspecific binding can be easily eliminated. By using this approach, we have identified several novel proteins that localize to ER-PM MCSs. Here we present a detailed description of our approach. 

Here we describe a new quantitative proteomics technique for identifying protein complexes in Saccharomyces cerevisiae. In this study, we have used the SILAC method together with affinity purification followed by tandem mass spectrometry to identify with high specificity the binding partners of an ER protein, Scs2p.

Lipids are the building blocks of cellular membranes that function as barriers and in compartmentalization of cellular processes, and recently, as ...

Quantitative Phosphoproteomics in Fatty Acid Stimulated Saccharomyces cerevisiae

This protocol describes the growth and stimulation, with the fatty acid oleate, of isotopically heavy and light S. cerevisiae cells. Cells are ground using a cryolysis procedure in a ball mill grinder and the resulting grindate brought into solution by urea solubilization. This procedure allows for the lysis of the cells in a metabolically inactive state, preserving phosphorylation and preventing reorientation of the phosphoproteome during cell lysis.  Following reduction, alkylation, trypsin digestion of the proteins, the samples are desalted on C18 columns and the sample complexity reduced by fractionation using hydrophilic interaction chromatography (HILIC). HILIC columns preferentially retain hydrophilic molecules which is well suited for phosphoproteomics.  Phosphorylated peptides tend to elute later in the chromatographic profile than the non phosphorylated counterparts. After fractionation, phosphopeptides are enriched using immobilized metal chromatography, which relies on charge-based affinities for phosphopeptide enrichment. At the end of this procedure the samples are ready to be quantitatively analyzed by mass spectrometry.

Quantitative Phosphoproteomics in Fatty Acid Stimulated Saccharomyces cerevisiae

Description of a quantitative phosphorylation procedure using cryolysis, urea solubilziation, HILIC fractionation and IMAC enrichment of phosphorylated peptides.

This protocol describes the growth and stimulation, with the fatty acid oleate, of isotopically heavy and light S. cerevisiae cells. Cells are ground ...

Microarray Analysis for Saccharomyces cerevisiae

In this protocol, gene expression in yeast (Saccharomyces cerevisiae) is changed after exposure to oxidative stress induced by the addition of hydrogen peroxide (H2O2), an oxidizing agent. In the experiment, yeast is grown for 48 hours in 1/2X YPD broth containing 3X glucose. The culture is split into a control and treated group. The experiment culture is treated with 0.5 mM H2O2 in Hanks Buffered Saline (HBSS) for 1 hour. The control culture is treated with HBSS only. Total RNA is extracted from both cultures and is converted to a biotin-labeled cRNA product through a multistep process. The final synthesis product is taken back to the UVM Microarray Core Facility and hybridized to the Affymetrix yeast GeneChips. The resulting gene expression data are uploaded into bioinformatics data analysis software.

Microarray Analysis for Saccharomyces cerevisiae

In this protocol, gene expression in yeast (Saccharomyces cerevisiae) is changed after exposure to oxidative stress induced by the addition of hydrogen peroxide (H2O2), an oxidizing agent.

In this protocol, gene expression in yeast (Saccharomyces cerevisiae) is changed after exposure to oxidative stress induced by the addition of hydrogen ...

Rapid Genetic Analysis of Epithelial-Mesenchymal Signaling During Hair Regeneration

Hair follicle morphogenesis, a complex process requiring interaction between epithelia-derived keratinocytes and the underlying mesenchyme, is an attractive model system to study organ development and tissue-specific signaling. Although hair follicle development is genetically tractable, fast and reproducible analysis of factors essential for this process remains a challenge. Here we describe a procedure to generate targeted overexpression or shRNA-mediated knockdown of factors using lentivirus in a tissue-specific manner. Using a modified version of a hair regeneration model 5, 6, 11, we can achieve robust gain- or loss-of-function analysis in primary mouse keratinocytes or dermal cells to facilitate study of epithelial-mesenchymal signaling pathways that lead to hair follicle morphogenesis. We describe how to isolate fresh primary mouse keratinocytes and dermal cells, which contain dermal papilla cells and their precursors, deliver lentivirus containing either shRNA or cDNA to one of the cell populations, and combine the cells to generate fully formed hair follicles on the backs of nude mice. This approach allows analysis of tissue-specific factors required to generate hair follicles within three weeks and provides a fast and convenient companion to existing genetic models.

Tissue-specific analysis of a hair follicle regeneration model using lentivirus to mediate gain- or loss-of-function.

Hair follicle morphogenesis, a complex process requiring interaction between epithelia-derived keratinocytes and the underlying mesenchyme, is an ...

Visualization and Analysis of mRNA Molecules Using Fluorescence In Situ Hybridization in Saccharomyces cerevisiae

The Fluorescence in situ Hybridization (FISH) method allows one to detect nucleic acids in the native cellular environment. Here we provide a protocol for using FISH to quantify the number of mRNAs in single yeast cells. Cells can be grown in any condition of interest and then fixed and made permeable. Subsequently, multiple single-stranded deoxyoligonucleotides conjugated to fluorescent dyes are used to label and visualize mRNAs. Diffraction-limited fluorescence from single mRNA molecules is quantified using a spot-detection algorithm to identify and count the number of mRNAs per cell. While the more standard quantification methods of northern blots, RT-PCR and gene expression microarrays provide information on average mRNAs in the bulk population, FISH facilitates both the counting and localization of these mRNAs in single cells at single-molecule resolution.

Visualization and Analysis of mRNA Molecules Using Fluorescence In Situ Hybridization in Saccharomyces cerevisiae

This protocol describes an experimental procedure for performing Fluorescence in situ Hybridization (FISH) for counting mRNAs in single cells at single-molecule resolution.

The Fluorescence in situ Hybridization (FISH) method allows one to detect nucleic acids in the native cellular environment. Here we provide a protocol for ...

Coupled Assays for Monitoring Protein Refolding in Saccharomyces cerevisiae

Proteostasis, defined as the combined processes of protein folding/biogenesis, refolding/repair, and degradation, is a delicate cellular balance that must be maintained to avoid deleterious consequences 1. External or internal factors that disrupt this balance can lead to protein aggregation, toxicity and cell death. In humans this is a major contributing factor to the symptoms associated with neurodegenerative disorders such as Huntington's, Parkinson's, and Alzheimer's diseases 10. It is therefore essential that the proteins involved in maintenance of proteostasis be identified in order to develop treatments for these debilitating diseases. This article describes techniques for monitoring in vivo protein folding at near-real time resolution using the model protein firefly luciferase fused to green fluorescent protein (FFL-GFP). FFL-GFP is a unique model chimeric protein as the FFL moiety is extremely sensitive to stress-induced misfolding and aggregation, which inactivates the enzyme 12. Luciferase activity is monitored using an enzymatic assay, and the GFP moiety provides a method of visualizing soluble or aggregated FFL using automated microscopy. These coupled methods incorporate two parallel and technically independent approaches to analyze both refolding and functional reactivation of an enzyme after stress. Activity recovery can be directly correlated with kinetics of disaggregation and re-solubilization to better understand how protein quality control factors such as protein chaperones collaborate to perform these functions. In addition, gene deletions or mutations can be used to test contributions of specific proteins or protein subunits to this process. In this article we examine the contributions of the protein disaggregase Hsp104 13, known to partner with the Hsp40/70/nucleotide exchange factor (NEF) refolding system 5, to protein refolding to validate this approach.

Coupled Assays for Monitoring Protein Refolding in Saccharomyces cerevisiae

This article describes the use of a firefly luciferase-GFP fusion protein to investigate in vivo protein folding in Saccharomyces cerevisiae. Using this reagent, refolding of a model heat-denatured protein can be monitored simultaneously by fluorescence microscopy and an enzymatic assay to probe the roles of proteostasis network components in protein quality control.

Proteostasis, defined as the combined processes of protein folding/biogenesis, refolding/repair, and degradation, is a delicate cellular balance that must ...

Purification of the Cystic Fibrosis Transmembrane Conductance Regulator Protein Expressed in Saccharomyces cerevisiae

Defects in the cystic fibrosis transmembrane conductance regulator (CFTR) protein cause cystic fibrosis (CF), an autosomal recessive disease that currently limits the average life expectancy of sufferers to &#60;40 years of age. The development of novel drug molecules to restore the activity of CFTR is an important goal in the treatment CF, and the isolation of functionally active CFTR is a useful step towards achieving this goal.
We describe two methods for the purification of CFTR from a eukaryotic heterologous expression system, S. cerevisiae. Like prokaryotic systems, S. cerevisiae can be rapidly grown in the lab at low cost, but can also traffic and posttranslationally modify large membrane proteins. The selection of detergents for solubilization and purification is a critical step in the purification of any membrane protein. Having screened for the solubility of CFTR in several detergents, we have chosen two contrasting detergents for use in the purification that allow the final CFTR preparation to be tailored to the subsequently planned experiments.
In this method, we provide comparison of the purification of CFTR in dodecyl-&#946;-D-maltoside (DDM) and 1-tetradecanoyl-sn-glycero-3-phospho-(1&#39;-rac-glycerol) (LPG-14). Protein purified in DDM by this method shows ATPase activity in functional assays. Protein purified in LPG-14 shows high purity and yield, can be employed to study post-translational modifications, and can be used for structural methods such as small-angle X-ray scattering and electron microscopy. However it displays significantly lower ATPase activity.

Purification of the Cystic Fibrosis Transmembrane Conductance Regulator Protein Expressed in Saccharomyces cerevisiae

Heterologous expression and purification of the cystic fibrosis transmembrane conductance regulator (CFTR) are significant challenges and limiting factors in the development of drug therapies for cystic fibrosis. This protocol describes two methods for the isolation of milligram quantities of CFTR suitable for functional and structural studies.&#160;

Defects in the cystic fibrosis transmembrane conductance regulator (CFTR) protein cause cystic fibrosis (CF), an autosomal recessive disease that ...

EPR Monitored Redox Titration of the Cofactors of Saccharomyces cerevisiae Nar1

Electron Paramagnetic Resonance (EPR) monitored redox titrations are a powerful method to determine the midpoint potential of cofactors in proteins and to identify and quantify the cofactors in their detectable redox state.
The technique is complementary to direct electrochemistry (voltammetry) approaches, as it does not offer information on electron transfer rates, but does establish the identity and redox state of the cofactors in the protein under study. The technique is widely applicable to any protein containing an electron paramagnetic resonance (EPR) detectable cofactor.
A typical titration requires 2 ml protein with a cofactor concentration in the range of 1-100 &#181;M. The protein is titrated with a chemical reductant (sodium dithionite) or oxidant (potassium ferricyanide) in order to poise the sample at a certain potential. A platinum wire and a Ag/AgCl reference electrode are connected to a voltmeter to measure the potential of the protein solution. A set of 13 different redox mediators is used to equilibrate between the redox cofactors of the protein and the electrodes. Samples are drawn at different potentials and the Electron Paramagnetic Resonance spectra, characteristic for the different redox cofactors in the protein, are measured. The plot of the signal intensity versus the sample potential is analyzed using the Nernst equation in order to determine the midpoint potential of the cofactor.

EPR Monitored Redox Titration of the Cofactors of Saccharomyces cerevisiae Nar1

The goal of this protocol is to use electron paramagnetic resonance (EPR) monitored redox titrations to identify different cofactors of Saccharomyces cerevisiae Nar1. Redox titrations offer a very robust way to obtain midpoint potentials of different redox active cofactors in enzymes and proteins.

Electron Paramagnetic Resonance (EPR) monitored redox titrations are a powerful method to determine the midpoint potential of cofactors in proteins and to ...

Measurement of mRNA Decay Rates in Saccharomyces cerevisiae Using rpb1-1 Strains

mRNA steady state levels vary depending on environmental conditions. Regulation of the steady state accumulation levels of an mRNA ensures that the correct amount of protein is synthesized for the cell&#8217;s specific growth conditions. One approach for measuring mRNA decay rates is inhibiting transcription and subsequently monitoring the disappearance of the already present mRNA. The rate of mRNA decay can then be quantified, and an accurate half-life can be determined utilizing several techniques. In S. cerevisiae, protocols that measure mRNA half-lives have been developed and include inhibiting transcription of mRNA using strains that harbor a temperature sensitive allele of RNA polymerase II, rpb1-1. Other techniques for measuring mRNA half-lives include inhibiting transcription with transcriptional inhibitors such as thiolutin or 1,10-phenanthroline, or alternatively, by utilizing mRNAs that are under the control of a regulatable promoter such as the galactose inducible promoter and the TET-off system. Here, we describe measurement of S. cerevisiae mRNA decay rates using the temperature sensitive allele of RNA polymerase II. This technique can be used to measure mRNA decay rates of individual mRNAs or genome-wide.

Measurement of mRNA Decay Rates in Saccharomyces cerevisiae Using rpb1-1 Strains

The steady state level of specific mRNAs is determined by the rate of synthesis and decay of the mRNA. Genome-wide mRNA degradation rates or the decay rates of specific mRNAs can be measured by determining mRNA half-lives. This protocol focuses on measurement of mRNA decay rates in Saccharomyces cerevisiae.

mRNA steady state levels vary depending on environmental conditions. Regulation of the steady state accumulation levels of an mRNA ensures that the ...