Name: characterizing histone post-translational modification alterations in yeast neurodegenerative proteinopathy models
Uploaded: 2019-03-24T13:00:00
Description: Watch this Scientific Journal Video about Characterizing Histone Post-translational Modification Alterations in Yeast Neurodegenerative Proteinopathy Models at JoVE.com

We thank Royena Tanaz, Huda Yousuf, and Sadiqa Taasen for technical help. We are very grateful to Prof. James Shorter for the generous provision of reagents and intellectual assistance in the design of sucrose tuning experiments. Yeast plasmids were a generous gift from Prof. Aaron Gitler (including 303Gal-FUS; Addgene plasmid # 29614). Brooklyn College and the Advanced Science Research Center (CUNY) as well as an NIH NINDS Advanced Postdoctoral Transition Award (K22NS09131401) supported M.P.T.

1. Transforming S. cerevisiae with neurodegenerative proteinopathy-associated protein constructs
<ol>
	<li>Grow wild type (WT) 303 yeast in yeast extract peptone dextrose (YPD) broth overnight with shaking (200 rpm) at 30 &#176;C.</li>
	<li>After 12&#8722;16 h of growth, dilute yeast to an optical density at 600 nm (OD600) of 0.25 with YPD. As 10 mL of yeast liquid culture will be needed for each transformation, prepare 50 mL of yeast liquid culture for five transformations corresponding to FUS, TDP...

<ol>
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The protocol described here provides a straightforward, expedient, and cost-effective way of categorizing genome-wide histone PTM changes correlated with neurodegenerative proteinopathies. While there are other models of ALS and PD, such as in vitro human cell lines and murine models32, S. cerevisiae remains attractive because of its ease of use. For instance, yeast models do not require use of a sterile hood, nor do they require the intensive training that goes along with cell c...

Neurodegenerative diseases are devastating illnesses with little to no treatment options available. Among these, amyotrophic lateral sclerosis (ALS) and Parkinson&#39;s disease (PD) are particularly dreadful. Approximately 90% of ALS and PD cases are considered sporadic, occurring without family history of the disease, while the remaining cases run in families and are generally linked to a specific gene mutation1,2. Interestingly, both of these diseases are associated with protein mislocalization and aggregation3,4,5,6. For instance, fused in sarcoma (FUS) and TAR DNA-binding protein 43 (TDP-43) are RNA binding proteins that mislocalize to the cytoplasm and aggregate in ALS7,8,9,10,11,12, while &#945;-synuclein is the principle component of proteinaceous aggregates termed Lewy bodies in PD5,13,14,15.
Despite the extensive genome-wide association efforts in large patient populations, the overwhelming majority of ALS and PD cases remain unexplained genetically. Can epigenetics play a role in neurodegenerative disease? Epigenetics comprises changes in gene expression occurring without changes to underlying DNA sequence16. A main epigenetic mechanism involves the post translational modifications (PTMs) of histone proteins16. In eukaryotic cells, genetic material is tightly wrapped into chromatin. The base unit of chromatin is the nucleosome, consisting of 146 base pairs of DNA wrapped around a histone octamer, composed of four pairs of histones (two copies each of histones H2A, H2B, H3, and H4)17. Each histone has an N-terminal tail that protrudes out of the nucleosome and can be modified by the addition of various chemical moieties, usually on lysine and arginine residues18. These PTMs are dynamic, which means they can be easily added and removed, and include groups such as acetylation, methylation, and phosphorylation. PTMs control the accessibility of DNA to the transcriptional machinery, and thus help control gene expression18. For example, histone acetylation reduces the strength of the electrostatic interaction between the highly basic histone protein and the negatively charged DNA backbone, allowing the genes packed by acetylated histones to be more accessible and thus highly expressed19. More recently, the remarkable biological specificity of particular histone PTMs and their combinations has led to the histone code hypothesis20,21 in which proteins that write, erase, and read histone PTMs all act in concert to modulate gene expression.
Yeast is a very useful model to study neurodegeneration. Importantly, many neuronal cellular pathways are conserved from yeast to humans22,23,24. Yeast recapitulate cytotoxicity phenotypes and protein inclusions upon overexpression of FUS, TDP-43, or &#945;-synuclein22,23,24,25,26. In fact, Saccharomyces cerevisiae models of ALS have been used to identify genetic risk factors in humans27. Furthermore, yeast overexpressing human &#945;-synuclein allowed for the characterization of the Rsp5 network as a druggable target to ameliorate &#945;-synuclein toxicity in neurons28,29.
Here, we describe a protocol exploiting Saccharomyces cerevisiae to detect genome-wide histone PTM changes associated with neurodegenerative proteinopathies (Figure 1). The use of S. cerevisiae is highly attractive because of its ease of use, low cost, and speed compared to other in vitro and animal models of neurodegeneration. Harnessing previously developed ALS and PD models22,23,25,26, we have overexpressed human FUS, TDP-43, and &#945;-synuclein in yeast and uncovered distinct histone PTM changes occurring in connection with each proteinopathy30. The protocol that we describe here can be completed in less than two weeks from transformation to data analysis.

<table>
	<tbody>
		<tr>
			<td>-His DO Supplement</td>
			<td>Clontech</td>
			<td>630415</td>
			<td></td>
		</tr>
		<tr>
			<td>10x Running Buffer</td>
			<td></td>
			<td></td>
			<td>Mix: 141.65 g glycine (ThermoFisher BP381-1), 30.3 g Tizma base (Sigma-Aldrich T6066), 10 g sodium dodecyl sulfate (Sigma-Aldrich L3771), and 1 L deionized water, pH 8.8.</td>
		</tr>
		<tr>
			<td>12% Polyacrylamide Gels</td>
			<td>BIO-RAD</td>
			<td>456-1041</td>
			<td></td>
		</tr>
		<tr>
			<td>2-mercaptoethanol</td>
			<td>Sigma-Aldrich</td>
			<td>M3148</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-acetyl-Histone H3 (Lys14) Primary Antibody</td>
			<td>MilliporeSigma</td>
			<td>07-353 (Lot No. 2762291)</td>
			<td>Dilution: 1/1000</td>
		</tr>
		<tr>
			<td>Anti-acetyl-Histone H4 (Lys 16) Primary Antibody</td>
			<td>Abcam</td>
			<td>ab109463 (Lot No. GR187780)</td>
			<td>Dilution: 1/2000</td>
		</tr>
		<tr>
			<td>Anti-acetyl-Histone H4 (Lys12) Primary Antibody</td>
			<td>Abcam</td>
			<td>ab46983 (Lot No. GR71882)</td>
			<td>Dilution: 1/5000</td>
		</tr>
		<tr>
			<td>Anti-dimethyl-Histone H3 (Lys36) Primary Antibody</td>
			<td>Abcam</td>
			<td>ab9049 (Lot No. GR266894, GR3236147)</td>
			<td>Dilution: 1/1000</td>
		</tr>
		<tr>
			<td>Anti-Histone H3 Primary Antibody</td>
			<td>Abcam</td>
			<td>ab24834 (Lot No. GR236539, GR174196, GR3194335)</td>
			<td>Nuclear Loading Control; Dilution: 1/2000</td>
		</tr>
		<tr>
			<td>Anti-phospho-Histone H2B (Thr129) Primary Antibody</td>
			<td>Abcam</td>
			<td>ab188292 (Lot No. GR211874)</td>
			<td>Dilution: 1/1000</td>
		</tr>
		<tr>
			<td>Anti-phospho-Histone H3 (Ser10) Primary Antibody</td>
			<td>Abcam</td>
			<td>ab5176 (Lot No. GR264582, GR192662, GR3217296)</td>
			<td>Dilution: 1/1000</td>
		</tr>
		<tr>
			<td>BioPhotometer D30</td>
			<td>Eppendorf</td>
			<td>6133000010</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell Culture Dish (100 x 20 mm)</td>
			<td>Eppendorf</td>
			<td>30702118</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell Culture Plate, 96 well</td>
			<td>Eppendorf</td>
			<td>30730011</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge 5804/5804 R/5810/5810 R</td>
			<td>Eppendorf</td>
			<td>22625501</td>
			<td></td>
		</tr>
		<tr>
			<td>Donkey Anti-Mouse IRDye 800 CW</td>
			<td>LI-COR</td>
			<td>926-32212 (Lot No. C60301-05, C61116-02, C80108-05)</td>
			<td>Dilution: 1/5000</td>
		</tr>
		<tr>
			<td>Donkey Anti-Rabbit IRDye 860 RD</td>
			<td>LI-COR</td>
			<td>926-68073 (Lot No. C60217-06, C70323-06, C70601-05, C80116-07)</td>
			<td>Dilution: 1/2500</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sigma-Aldrich</td>
			<td>E7023</td>
			<td></td>
		</tr>
		<tr>
			<td>Extra thick blot paper (filter paper)</td>
			<td>BIO-RAD</td>
			<td>1703968</td>
			<td></td>
		</tr>
		<tr>
			<td>Galactose</td>
			<td>Sigma-Aldrich</td>
			<td>G0750</td>
			<td>Prepare 20% w/v stock solution.</td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td>Sigma-Aldrich</td>
			<td>G8270</td>
			<td>Prepare 20% w/v stock solution.</td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Sigma-Aldrich</td>
			<td>G5516</td>
			<td>Prepare 50 % w/v solution.</td>
		</tr>
		<tr>
			<td>Immobilon-FL Transfer Membranes</td>
			<td>MilliporeSigma</td>
			<td>IPFL00010</td>
			<td></td>
		</tr>
		<tr>
			<td>Lithium acetate dihydrate (LiAc)</td>
			<td>Sigma-Aldrich</td>
			<td>L4158</td>
			<td>Prepare a 1 M solution.</td>
		</tr>
		<tr>
			<td>Loading Dye</td>
			<td></td>
			<td></td>
			<td>Mix: 1.2 g sodium dodecyl sulfate, 6 mg bromophenol blue (Sigma-Aldrich B8026), 4.7 mL glycerol, 1.2 mL 0.5M Trizma base pH 6.8, 0.93 g DL-Dithiothreitol (Sigma-Aldrich D0632), and 2.1 mL deionized water.</td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>ThermoFisher</td>
			<td>A412-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Mini-PROTEAN Tetra Vertical Electrophoeresis Cell</td>
			<td>BIO-RAD</td>
			<td>1658004</td>
			<td></td>
		</tr>
		<tr>
			<td>Multichannel pipet</td>
			<td>Eppendorf</td>
			<td>2231300045</td>
			<td></td>
		</tr>
		<tr>
			<td>NEB Restriction Enzyme Buffer 2.1, 10x</td>
			<td>New England Bio Labs</td>
			<td>102855-152</td>
			<td></td>
		</tr>
		<tr>
			<td>Nhe I Restriction Enzyme</td>
			<td>New England Bio Labs</td>
			<td>101228-710</td>
			<td></td>
		</tr>
		<tr>
			<td>Nuclease Free Water</td>
			<td>Qiagen</td>
			<td>129114</td>
			<td></td>
		</tr>
		<tr>
			<td>Odyssey Fc Imaging System</td>
			<td>LI-COR Biosciences</td>
			<td>2800-03</td>
			<td></td>
		</tr>
		<tr>
			<td>OmniTray Cell Culture Treated w/Lid Sterile, PS (86 x 128 mm)</td>
			<td>ThermoFisher</td>
			<td>165218</td>
			<td></td>
		</tr>
		<tr>
			<td>pAG303GAL-a-synuclein-GFP</td>
			<td>Gift from A. Gitler</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>pAG303GAL-ccdB</td>
			<td>Addgene</td>
			<td>14133</td>
			<td></td>
		</tr>
		<tr>
			<td>pAG303Gal-FUS</td>
			<td>Addgene</td>
			<td>29614</td>
			<td></td>
		</tr>
		<tr>
			<td>pAG303GAL-TDP-43</td>
			<td>Gift from A. Gitler</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Poly(ethylene glycol) (PEG)</td>
			<td>Sigma-Aldrich</td>
			<td>P4338</td>
			<td>Prepare a 50% w/v solution.</td>
		</tr>
		<tr>
			<td>Ponceau S Stain</td>
			<td>Sigma-Aldrich</td>
			<td>P3504</td>
			<td>Mix: 0.5 g 0.1% w/w Ponceau S dye, 5 mL 1% v/v acetic acid (Sigma-Aldrich 320099), and 500 mL deionized water.</td>
		</tr>
		<tr>
			<td>PowerPac Basic Power Supply</td>
			<td>BIO-RAD</td>
			<td>164-5050</td>
			<td></td>
		</tr>
		<tr>
			<td>Raffinose pentahydrate</td>
			<td>Sigma-Aldrich</td>
			<td>R7630</td>
			<td>Prepare 10% w/v stock solution.</td>
		</tr>
		<tr>
			<td>Salmon Sperm DNA</td>
			<td>Agilent Tech</td>
			<td>201190</td>
			<td></td>
		</tr>
		<tr>
			<td>SD-His plates</td>
			<td></td>
			<td></td>
			<td>Mix: 20 g Agar (Sigma-Aldrich A1296), 0.77 g -His DO supplement, 6.7 g yeast Nitrogen Base w/o amino acids (ThermoFisher 291920), and 900 mL deionized water.</td>
		</tr>
		<tr>
			<td>SGal-His plates</td>
			<td></td>
			<td></td>
			<td>Mix: 20 g Agar, 0.77 g -His DO supplement, 6.7 g yeast Nitrogen Base w/o amino acids, 100 mL galactose solution, and 900 mL deionized water.</td>
		</tr>
		<tr>
			<td>Sodium dodecyl sulfate Loading Buffer</td>
			<td></td>
			<td></td>
			<td>Store at -20 oC. 6X, Mix: 1.2 g sodium dodecyl sulfate, 6 mg bromophenol blue, 0.93 g DL-Dithiothreitol, 2.1 mL deionized water, 4.7 mL glycerol, and 1.2 mL 0.5 M Trizma base, pH 6.8.</td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>Sigma-Aldrich</td>
			<td>221465</td>
			<td>Prepare 0.2 M solution.</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Sigma-Aldrich</td>
			<td>84097</td>
			<td>Prepare 20% w/v stock solution.</td>
		</tr>
		<tr>
			<td>TBS + 0.1% Tween 20 (TBST)</td>
			<td></td>
			<td></td>
			<td>Mix: 100 mL 10X TBS, 1 mL Tween 20 (Sigma-Aldrich P7949), and 900 mL deionized water.</td>
		</tr>
		<tr>
			<td>TBS Blocking Buffer</td>
			<td>LI-COR</td>
			<td>927-5000</td>
			<td></td>
		</tr>
		<tr>
			<td>Trans-Blot SD Semi-Dry Electrophoretic Transfer Cell</td>
			<td>BIO-RAD</td>
			<td>170-3940</td>
			<td></td>
		</tr>
		<tr>
			<td>Transfer Buffer</td>
			<td></td>
			<td></td>
			<td>Mix: 22.5 g glycine, 4.84 g Tizma base, 400 mL methanol, 1 g sodium dodecyl sulfate, and 1.6 L deionized water.</td>
		</tr>
		<tr>
			<td>Tris-Buffered Saline (TBS)</td>
			<td></td>
			<td></td>
			<td>10X, 7.6 pH, Solution: Mix 24 g Trizma base, and 88 g sodium chloride (Sigma-Aldrich S7653). Fill to 1 L with deionized water.</td>
		</tr>
		<tr>
			<td>WT 303 S. cerevisiae yeast</td>
			<td>Gift from J. Shorter</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Yeast Extract Peptone Dextrose (YPD)</td>
			<td>Sigma-Aldrich</td>
			<td>Y1375</td>
			<td></td>
		</tr>
	</tbody>
</table>

characterizing histone post-translational modification alterations in yeast neurodegenerative proteinopathy models

Neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) and Parkinson&#39;s disease (PD), cause the loss of hundreds of thousands of lives each year. Effective treatment options able to halt disease progression are lacking. Despite the extensive sequencing efforts in large patient populations, the majority of ALS and PD cases remain unexplained by genetic mutations alone. Epigenetics mechanisms, such as the post-translational modification of histone proteins, may be involved in neurodegenerative disease etiology and progression and lead to new targets for pharmaceutical intervention. Mammalian in vivo and in vitro models of ALS and PD are costly and often require prolonged and laborious experimental protocols. Here, we outline a practical, fast, and cost-effective approach to determining genome-wide alterations in histone modification levels using Saccharomyces cerevisiae as a model system. This protocol allows for comprehensive investigations into epigenetic changes connected to neurodegenerative proteinopathies that corroborate previous findings in different model systems while significantly expanding our knowledge of the neurodegenerative disease epigenome.

To illustrate this method, we will take advantage of recently published results30. WT human FUS and TDP-43 were overexpressed for 5 h, while WT &#945;-synuclein was overexpressed for 8 h. A ccdB construct was used as a vector negative control. Figure 2 shows growth suppression in solid and liquid cultures. Yeast was harvested as described and Western blotting with modification-specific antibodies was performed. Anti-total H3 was used a...

Watch this Scientific Journal Video about Characterizing Histone Post-translational Modification Alterations in Yeast Neurodegenerative Proteinopathy Models at JoVE.com

Characterizing Histone Post-translational Modification Alterations in Yeast Neurodegenerative Proteinopathy Models

This protocol outlines experimental procedures to characterize genome-wide changes in the levels of histone post-translational modifications (PTM) occurring in connection with the overexpression of proteins associated with ALS and Parkinson&#39;s disease in Saccharomyces cerevisiae models. After SDS-PAGE separation, individual histone PTM levels are detected with modification-specific antibodies via Western blotting.

Neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) and Parkinson&#39;s disease (PD), cause the loss of hundreds of thousands of lives ...

This protocol allows us to easily explore the epigenetic features of neurodegenerative disease. The main advantage of this technique is that it exploits yeast as a model system, compared to other cellular and animal models of neurodegenerative disease, yeast is expedient and cost-efficient. This technique allows us to map out the epigenetic changes that arise in neurodegenerative disease, which may lead to novel markers for diagnosis, as well as new targets for therapy.This method allows further investigation of the role of epigenetic marks in neurodegenerative disease and can be modified for the assessment of human fibroblasts and induced pluripotent stem cells. This particular method contains a number of details that need to be demonstrated visually, such as the proper loading of the Western blot apparatus. Demonstrating the procedure will be Michel Fallah and Navin Rana, both undergraduate researchers in the Torrente laboratory.Begin by restreaking yeast from frozen glycerol stocks onto histidine 2%glucose agar selective medium plates, for a two to three day incubation at 30 degrees Celsius. At the end of the incubation, inoculate restreaked yeast for each over expression model and control in five milliliters of histidine selective liquid medium. Supplemented with 2%raffinose at 30 degrees Celsius and 200 rotations per minute, overnight.The next morning, grow 100 milliliters of liquid culture for each of the overexpression models and controls in selective mediums supplemented with 2%galactose overnight. And measure the optical density at 600 nanometers or OD600 to determine the volume of overnight culture needed to render over expression cultures at a starting OD600 of 0.3. To induce protein overexpression, grow the yeast on galactose medium with shaking at 30 degrees Celsius for the appropriate experimental time period.Then measure the OD600 of each culture at the end of the induction period. And standardize all of the cell counts to the lowest OD600 value. Harvest the cultures in 50 milliliter centrifuge tubes by centrifugation and resuspend the pellets in one milliliter of sterile stilled water for every 10 milliliters of culture grown.Aliquot one milliliter of cell resuspension into individual microcentrifuge tubes for an additional centrifugation and aspirate the supernatants. Then snap freeze the cell pellets in liquid nitrogen for storage at minus 80 degrees celsius. To lyse the cells for Western blot analysis, thaw the yeast cell pellets on ice before resuspension in 100 microliters of distilled water.Add 300 microliters of 0.2-molar sodium hydroxide and 20 microliters of 2-Mercaptoethanol to each cell sample. And resuspend the pellets by pipetting. After a 10 minute incubation on ice, pellet the cells by centrifugation and resuspend the samples in 100 microliters of loading dye.Then boil the samples for 10 minutes on a heating block. While the samples are being lysed, place two gels in a gel holder and fill the inner chamber to the top with running buffer and the outside chamber to the two-gel line mark. When the samples are ready, load 15 microliters each, cell lysis solution, into each well of the 10 well, 12%polyacrylamide gel and add five microliters of protein ladder to the protein ladder lane well.Run the gel for approximately 45 minutes at 150 volts or until loading dye front reaches the bottom of the gel. While the gel is running, soak two fiber pads per gel in transfer buffer and one polyvinylidene fluoride, or PVDF, membrane per gel in methanol. When the gel is ready, rinse membrane in transfer buffer and place one presoaked fiber pad on the bottom of a semi-dry transfer apparatus cell.Followed by the PVDF membrane, the gel and the second presoaked fiber pad. Then set the power to 150 milliamps for one hour. At the end of the protein transfer, remove the membrane from the transfer apparatus for a brief rinse with distilled water.Place the rinsed membrane, protein side up in a small staining box and cover the membrane with tris-buffered saline or TBS, blocking buffer for a one hour incubation at room temperature with gentle rocking. At the end of the blocking incubation, incubate the membrane overnight with an anti-yeast histone and modification-specific antibody in TBS at four degrees Celsius. And a proper nuclear loading control antibody.The next morning, wash the membrane four times in TBS, supplemented with 0.1%polysorbate 20 for five minutes with rocking at room temperature per wash. After the last wash, incubate the blot with the appropriate secondary antibodies for one hour at room temperature. Followed by four, five minute washes in TBST and one five minute wash in TBS alone with rocking.Then image the blot on a fluorescent Western blot imagining system for two minutes. Here, growth suppression in solid and liquid cultures is shown with significant effects on yeast growth observed in the presence of galactose-infused in sarcoma overexpression models. A significant decrease in histone levels are apparent in the fused in sarcoma overexpression model and significant increases in the levels of histone acetylation in the TAR binding protein 43 overexpression model, are observed that are not seen in either the fused in sarcoma or alpha synuclein overexpression model.There are also significant decreases in the histone levels in the alpha synuclein overexpression model. In this sucrose-tuning experiment, the lower the amount of galactose used to induce fused in sarcoma overexpression, the lower toxicity that is observed in both solid and liquid culture. Importantly, the lower the level of fused in sarcoma overexpression, the smaller the magnitude of the reduction in histone levels.While performing this protocol, it is imperative to standardize the amount of yeast in each sample to enable a proper comparison in the levels of histone post-translational modification. 2-Mercaptoethanol should be used under a hood to avoid inhalation. If Ponceau stain is used, it must be discarded properly.

characterizing-histone-post-translational-modification-alterations

Research

JoVE Journal

Genetics

Optogenetic Random Mutagenesis Using Histone-miniSOG in C. elegans

Forward genetic screening in model organisms is the workhorse to discover functionally important genes and pathways in many biological processes. In most mutagenesis-based screens, researchers have relied on the use of toxic chemicals, carcinogens, or irradiation, which requires designated equipment, safety setup, and/or disposal of hazardous materials. We have developed a simple approach to induce heritable mutations in C. elegans using germline-expressed histone-miniSOG, a light-inducible potent generator of reactive oxygen species. This mutagenesis method is free of toxic chemicals and requires minimal laboratory safety and waste management. The induced DNA modifications include single-nucleotide changes and small deletions, and complement those caused by classical chemical mutagenesis. This methodology can also be used to induce integration of extrachromosomal transgenes. Here, we provide the details of the LED setup and protocols for standard mutagenesis and transgene integration.

Optogenetic Random Mutagenesis Using Histone-miniSOG in C. elegans

Genetically-encoded histone-miniSOG induces genome-wide heritable mutations in a blue&#160;light-dependent manner. This mutagenesis method is simple, fast, free of toxic chemicals, and well-suited for forward genetic screening and transgene integration.

Forward genetic screening in model organisms is the workhorse to discover functionally important genes and pathways in many biological processes. In most ...

Detection of Copy Number Alterations Using Single Cell Sequencing

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

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

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

Targeted in Situ Mutagenesis of Histone Genes in Budding Yeast

We describe a PCR- and homologous recombination-based system for generating targeted mutations in histone genes in budding yeast cells. The resulting mutant alleles reside at their endogenous genomic sites and no exogenous DNA sequences are left in the genome following the procedure. Since in haploid yeast cells each of the four core histone proteins is encoded by two non-allelic genes with highly homologous open reading frames (ORFs), targeting mutagenesis specifically to one of two genes encoding a particular histone protein can be problematic. The strategy we describe here bypasses this problem by utilizing sequences outside, rather than within, the ORF of the target genes for the homologous recombination step. Another feature of this system is that the regions of DNA driving the homologous recombination steps can be made to be very extensive, thus increasing the likelihood of successful integration events. These features make this strategy particularly well-suited for histone gene mutagenesis, but can also be adapted for mutagenesis of other genes in the yeast genome.

Targeted in Situ Mutagenesis of Histone Genes in Budding Yeast

A strategy for generating mutations in histone genes at their endogenous location in Saccharomyces cerevisiae is presented.

We describe a PCR- and homologous recombination-based system for generating targeted mutations in histone genes in budding yeast cells. The resulting ...

Constitutive and Inducible Systems for Genetic In Vivo Modification of Mouse Hepatocytes Using Hydrodynamic Tail Vein Injection

In research models of liver cancer, regeneration, inflammation, and fibrosis, flexible systems for in vivo gene expression and silencing are highly useful. Hydrodynamic tail vein injection of transposon-based constructs is an efficient method for genetic manipulation of hepatocytes in adult mice. In addition to constitutive transgene expression, this system can be used for more advanced applications, such as shRNA-mediated gene knock-down, implication of the CRISPR/Cas9 system to induce gene mutations, or inducible systems. Here, the combination of constitutive CreER expression together with inducible expression of a transgene or miR-shRNA of choice is presented as an example of this technique. We cover the multi-step procedure starting from the preparation of sleeping beauty-transposon constructs, to the injection and treatment of mice, and the preparation of liver tissue for analysis by immunostaining. The system presented is a reliable and efficient approach to achieve complex genetic manipulations in hepatocytes. It is specifically useful in combination with Cre/loxP-based mouse strains and can be applied to a variety of models in the research of liver disease.

Constitutive and Inducible Systems for Genetic In Vivo Modification of Mouse Hepatocytes Using Hydrodynamic Tail Vein Injection

Hydrodynamic tail vein injection of transposon-based integration vectors enables stable transfection of murine hepatocytes in vivo. Here, we present a practical protocol for transfection systems that enables the long-term constitutive expression of a single transgene or combined constitutive and doxycycline-inducible expression of a transgene or miR-shRNA in the liver.

In research models of liver cancer, regeneration, inflammation, and fibrosis, flexible systems for in vivo gene expression and silencing are highly ...

Chromatin Immunoprecipitation (ChIP) of Histone Modifications from Saccharomyces cerevisiae

Histone post-translational modifications (PTMs), such as acetylation, methylation and phosphorylation, are dynamically regulated by a series of enzymes that add or remove these marks in response to signals received by the cell. These PTMS are key contributors to the regulation of processes such as gene expression control and DNA repair. Chromatin immunoprecipitation (chIP) has been an instrumental approach for dissecting the abundance and localization of many histone PTMs throughout the genome in response to diverse perturbations to the cell. Here, a versatile method for performing chIP of post-translationally modified histones from the budding yeast Saccharomyces cerevisiae (S. cerevisiae) is described. This method relies on crosslinking of proteins and DNA using formaldehyde treatment of yeast cultures, generation of yeast lysates by bead beating, solubilization of chromatin fragments by micrococcal nuclease, and immunoprecipitation of histone-DNA complexes. DNA associated with the histone mark of interest is purified and subjected to quantitative PCR analysis to evaluate its enrichment at multiple loci throughout the genome. Representative experiments probing the localization of the histone marks H3K4me2 and H4K16ac in wildtype and mutant yeast are discussed to demonstrate data analysis and interpretation. This method is suitable for a variety of histone PTMs and can be performed with different mutant strains or in the presence of diverse environmental stresses, making it an excellent tool for investigating changes in chromatin dynamics under different conditions.

Chromatin Immunoprecipitation ChIP of Histone Modifications from Saccharomyces cerevisiae

Here, we describe a protocol for chromatin immunoprecipitation of modified histones from the budding yeast Saccharomyces cerevisiae. Immunoprecipitated DNA is subsequently used for quantitative PCR to interrogate the abundance and localization of histone post-translational modifications throughout the genome.

Histone post-translational modifications (PTMs), such as acetylation, methylation and phosphorylation, are dynamically regulated by a series of enzymes ...

Gene-targeted Random Mutagenesis to Select Heterochromatin-destabilizing Proteasome Mutants in Fission Yeast

Random mutagenesis of a target gene is commonly used to identify mutations that yield the desired phenotype. Of the methods that may be used to achieve random mutagenesis, error-prone PCR is a convenient and efficient strategy for generating a diverse pool of mutants (i.e., a mutant library). Error-prone PCR is the method of choice when a researcher seeks to mutate a pre-defined region, such as the coding region of a gene while leaving other genomic regions unaffected. After the mutant library is amplified by error-prone PCR, it must be cloned into a suitable plasmid. The size of the library generated by error-prone PCR is constrained by the efficiency of the cloning step. However, in the fission yeast, Schizosaccharomyces pombe, the cloning step can be replaced by the use of a highly efficient one-step fusion PCR to generate constructs for transformation. Mutants of desired phenotypes may then be selected using appropriate reporters. Here, we describe this strategy in detail, taking as an example, a reporter inserted at centromeric heterochromatin.

This article describes a detailed methodology for random mutagenesis of a target gene in fission yeast. As an example, we target rpt4+, which encodes a subunit of the 19S proteasome, and screen for mutations that destabilize heterochromatin.

Random mutagenesis of a target gene is commonly used to identify mutations that yield the desired phenotype. Of the methods that may be used to achieve ...

A Fast and Quantitative Method for Post-translational Modification and Variant Enabled Mapping of Peptides to Genomes

Cross-talk between genes, transcripts, and proteins is the key to cellular responses; hence, analysis of molecular levels as distinct entities is slowly being extended to integrative studies to enhance the understanding of molecular dynamics within cells. Current tools for the visualization and integration of proteomics with other omics datasets are inadequate for large-scale studies. Furthermore, they only capture basic sequence identify, discarding post-translational modifications and quantitation. To address these issues, we developed PoGo to map peptides with associated post-translational modifications and quantification to reference genome annotation. In addition, the tool was developed to enable the mapping of peptides identified from customized sequence databases incorporating single amino acid variants. While PoGo is a command line tool, the graphical interface PoGoGUI enables non-bioinformatics researchers to easily map peptides to 25 species supported by Ensembl genome annotation. The generated output borrows file formats from the genomics field and, therefore, visualization is supported in most genome browsers. For large-scale studies, PoGo is supported by TrackHubGenerator to create web-accessible repositories of data mapped to genomes that also enable an easy sharing of proteogenomics data. With little effort, this tool can map millions of peptides to reference genomes within only a few minutes, outperforming other available sequence-identity based tools. This protocol demonstrates the best approaches for proteogenomics mapping through PoGo with publicly available datasets of quantitative and phosphoproteomics, as well as large-scale studies.

Here we present the proteogenomic tool PoGo and protocols for fast, quantitative, post-translational modification and variant enabled mapping of peptides identified through mass spectrometry onto reference genomes. This tool is of use to integrate and visualize proteogenomic and personal proteomic studies interfacing with orthogonal genomics data.

Cross-talk between genes, transcripts, and proteins is the key to cellular responses; hence, analysis of molecular levels as distinct entities is slowly ...

Single Molecule Fluorescence In Situ Hybridization (smFISH) Analysis in Budding Yeast Vegetative Growth and Meiosis

Single molecule fluorescence in situ hybridization (smFISH) is a powerful technique to study gene expression in single cells due to its ability to detect and count individual RNA molecules. Complementary to deep sequencing-based methods, smFISH provides information about the cell-to-cell variation in transcript abundance and the subcellular localization of a given RNA. Recently, we have used smFISH to study the expression of the gene&#160;NDC80&#160;during meiosis in budding yeast, in which two transcript isoforms exist and the short transcript isoform has its entire sequence shared with the long isoform. To confidently identify each transcript isoform, we optimized known smFISH protocols and obtained high consistency and quality of smFISH data for the samples acquired during budding yeast meiosis. Here, we describe this optimized protocol, the criteria that we use to determine whether high quality of smFISH data is obtained, and some tips for implementing this protocol in&#160;other yeast strains and growth conditions.

Single Molecule Fluorescence In Situ Hybridization smFISH Analysis in Budding Yeast Vegetative Growth and Meiosis

This single molecule fluorescence in situ hybridization protocol is optimized to quantify the number of RNA molecules in budding yeast during vegetative growth and meiosis.

Single molecule fluorescence in situ hybridization (smFISH) is a powerful technique to study gene expression in single cells due to its ability to detect ...

Mating-based Overexpression Library Screening in Yeast

Budding yeast has been widely used as a model in studying proteins associated with human diseases. Genome-wide genetic screening is a powerful tool commonly used in yeast studies. The expression of a number of neurodegenerative disease-associated proteins in yeast causes cytotoxicity and aggregate formation, recapitulating findings seen in patients with these disorders. Here, we describe a method for screening a yeast model of the Amyotrophic Lateral Sclerosis-associated protein FUS for modifiers of its toxicity. Instead of using transformation, this new screening platform relies on the mating of yeast to introduce an arrayed library of plasmids into the yeast model. The mating method has two clear advantages: first, it is highly efficient; second, the pre-transformed arrayed library of plasmids can be stored for long-term as a glycerol stock, and quickly applied to other screens without the labor-intensive step of transformation into the yeast model each time. We demonstrate how this method can successfully be used to screen for genes that modify the toxicity of FUS.

This article presents a mating-based method to facilitate overexpression screening in budding yeast using an arrayed plasmid library.

Budding yeast has been widely used as a model in studying proteins associated with human diseases. Genome-wide genetic screening is a powerful tool ...

A Deep-sequencing-assisted, Spontaneous Suppressor Screen in the Fission Yeast Schizosaccharomyces pombe

A genetic screen for mutant alleles that suppress phenotypic defects caused by a mutation is a powerful approach to identify genes that belong to closely related biochemical pathways. Previous methods such as the Synthetic Genetic Array (SGA) analysis, and random mutagenesis techniques using ultraviolet (UV) or chemicals like ethyl methanesulfonate (EMS) or N-ethyl-N- nitrosourea (ENU), have been widely used but are often costly and laborious. Also, these mutagen-based screening methods are frequently associated with severe side effects on the organism, inducing multiple mutations that add to the complexity of isolating the suppressors. Here, we present a simple and effective protocol to identify suppressor mutations in mutants which confer a growth defect in Schizosaccharomyces pombe. The fitness of cells with a growth deficiency in standard rich liquid media or synthetic liquid media can be monitored for recovery using an automated 96-well plate reader over an extended period. Once a cell acquires a suppressor mutation in the culture, its descendants outcompete those of the parental cells. The recovered cells that have a competitive growth advantage over the parental cells can then be isolated and backcrossed with the parental cells. The suppressor mutations are then identified using whole-genome sequencing. Using this approach, we have successfully isolated multiple suppressors that alleviate the severe growth defects caused by loss of Elf1, an AAA+ family ATPase that is important in nuclear mRNA transport and maintenance of genomic stability. There are currently over 400 genes in S. pombe with mutants conferring a growth defect. As many of these genes are uncharacterized, we propose that our method will hasten the identification of novel functional interactions with this user-friendly, high-throughput approach.

A Deep-sequencing-assisted, Spontaneous Suppressor Screen in the Fission Yeast Schizosaccharomyces pombe

We present a simple suppressor screen protocol in fission yeast. This method is efficient, mutagen-free, and&#160; selective&#160; for&#160; mutations that&#160; often&#160; occur at&#160; &#160;a&#160; single&#160; genomic&#160; locus.&#160; The protocol is suitable for isolating suppressors that alleviate growth defects in liquid culture that are caused by a mutation or a drug.

A genetic screen for mutant alleles that suppress phenotypic defects caused by a mutation is a powerful approach to identify genes that belong to closely ...