Name: atac-seq assay with low mitochondrial dna contamination from primary human cd4+ t lymphocytes
Uploaded: 2019-03-22T14:00:00
Description: Watch this Scientific Journal Video about ATAC-seq Assay with Low Mitochondrial DNA Contamination from Primary Human CD4+ T Lymphocytes at JoVE.com

We thank Atsede Siba for technical support. C.S.C. is supported by NIH grant 1R61DA047032.

This improved protocol provides step-by-step instructions for performing ATAC-seq of CD4+ lymphocytes, from the starting material of whole blood through data analysis (Figure 1).
1. Isolation of CD4+ T Cells from Whole Blood
NOTE: The starting material for this protocol is 15 mL of fresh whole blood collected using standard procedures, allowing the source of the starting material to be selected based on research requireme...

<ol>
	<li>Buenrostro, J. D., Giresi, P. G., Zaba, L. C., Chang, H. Y., Greenleaf, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transposition+of+native+chromatin+for+fast+and+sensitive+epigenomic+profiling+of+open+chromatin,+DNA-binding+proteins+and+nucleosome+position.">Transposition of native chromatin for fast and sensitive epigenomic profiling of open chromatin, DNA-binding proteins and nucleosome position.</a> Nature Methods. 10 (12), 1213-1218 (2013).</li><li>Buenrostro, J. D., Wu, B., Chang, H. Y., Greenleaf, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ATAC-seq:+A+Method+for+Assaying+Chromatin+Accessibility+Genome-Wide.">ATAC-seq: A Method for Assaying Chromatin Accessibility Genome-Wide.</a> Current Protocols in Molecular Biology. 21, 1-29 (2015).</li><li>Song, L., Crawford, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNase-seq:+a+high-resolution+technique+for+mapping+active+gene+regulatory+elements+across+the+genome+from+mammalian+cells.">DNase-seq: a high-resolution technique for mapping active gene regulatory elements across the genome from mammalian cells.</a> Cold Spring Harbor Protocols. (2), (2010).</li><li>Pajoro, A., Mui&#241;o, J. M., Angenent, G. C., Kaufmann, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Profiling+Nucleosome+Occupancy+by+MNase-seq:+Experimental+Protocol+and+Computational+Analysis.">Profiling Nucleosome Occupancy by MNase-seq: Experimental Protocol and Computational Analysis.</a> Methods in Molecular Biology. 1675, 167-181 (2018).</li><li>Giresi, P. G., Kim, J., McDaniell, R. M., Iyer, V. R., Lieb, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FAIRE+(Formaldehyde-Assisted+Isolation+of+Regulatory+Elements)+isolates+active+regulatory+elements+from+human+chromatin.">FAIRE (Formaldehyde-Assisted Isolation of Regulatory Elements) isolates active regulatory elements from human chromatin.</a> Genome Research. 17 (6), 877-885 (2007).</li><li>Rosenberg, 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=Single-cell+profiling+of+the+developing+mouse+brain+and+spinal+cord+with+split-pool+barcoding.">Single-cell profiling of the developing mouse brain and spinal cord with split-pool barcoding.</a> Science. 360 (6385), 176-182 (2018).</li><li>Corces, M. R., 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=Lineage-specific+and+single-cell+chromatin+accessibility+charts+human+hematopoiesis+and+leukemia+evolution.">Lineage-specific and single-cell chromatin accessibility charts human hematopoiesis and leukemia evolution.</a> Nature Genetics. 48 (10), 1193-1203 (2016).</li><li>Lu, Z., Hofmeister, B. T., Vollmers, C., DuBois, R. M., Schmitz, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combining+ATAC-seq+with+nuclei+sorting+for+discovery+of+cis-regulatory+regions+in+plant+genomes.">Combining ATAC-seq with nuclei sorting for discovery of cis-regulatory regions in plant genomes.</a> Nucleic Acids Research. 45 (6), e41 (2017).</li><li>Lara-Astiaso, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromatin+state+dynamics+during+blood+formation.">Chromatin state dynamics during blood formation.</a> Science. 345 (6199), 943-949 (2014).</li><li>Gate, R. 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=Genetic+determinants+of+co-accessible+chromatin+regions+in+activated+T+cells+across+humans.">Genetic determinants of co-accessible chromatin regions in activated T cells across humans.</a> Nature Genetics. , (2018).</li><li>Sanjana, N. 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=High-resolution+interrogation+of+functional+elements+in+the+noncoding+genome.">High-resolution interrogation of functional elements in the noncoding genome.</a> Science. 353 (6307), 1545-1549 (2016).</li><li>. FastQC A Quality Control tool for High Throughput Sequence Data. Babraham Bioinformatics Available from: <a target="_blank" href="https://www.bioinformatics.babraham.ac.uk/projects/fastqc">https://www.bioinformatics.babraham.ac.uk/projects/fastqc</a> (2018)</li><li>Bolger, A. M., Lohse, M., Usadel, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trimmomatic:+a+flexible+trimmer+for+Illumina+sequence+data.">Trimmomatic: a flexible trimmer for Illumina sequence data.</a> Bioinformatics. 30 (15), 2114-2120 (2014).</li><li>Langmead, B., Salzberg, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fast+gapped-read+alignment+with+Bowtie+2.">Fast gapped-read alignment with Bowtie 2.</a> Nature Methods. 9 (4), 357-359 (2012).</li><li>Li, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Sequence+Alignment/Map+format+and+SAMtools.">The Sequence Alignment/Map format and SAMtools.</a> Bioinformatics. 25 (16), 2078-2079 (2009).</li><li>Quinlan, A. R., Hall, I. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=BEDTools:+a+flexible+suite+of+utilities+for+comparing+genomic+features.">BEDTools: a flexible suite of utilities for comparing genomic features.</a> Bioinformatics. 26 (6), 841-842 (2010).</li><li>Corces, M. R., 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=An+improved+ATAC-seq+protocol+reduces+background+and+enables+interrogation+of+frozen+tissues.">An improved ATAC-seq protocol reduces background and enables interrogation of frozen tissues.</a> Nature Methods. 14 (10), 959-962 (2017).</li><li>Wu, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+landscape+of+accessible+chromatin+in+mammalian+preimplantation+embryos.">The landscape of accessible chromatin in mammalian preimplantation embryos.</a> Nature. 534 (7609), 652-657 (2016).</li></ol>

The modified ATAC-seq protocol presented in this article provides reproducible results with minimal mitochondrial DNA contamination. The protocol has been used to successfully characterize chromatin architecture of human primary PBMCs10, human monocytes, mouse dendritic cells (unpublished), and cultured melanoma cell lines11. We anticipate this improved lysis condition has the potential to work for other cell types as well. It is also anticipated that this nuclei isolation ...

The assay for transposase-accessible chromatin sequencing (ATAC-seq) has rapidly become the leading method for interrogating chromatin architecture. ATAC-seq can identify regions of accessible chromatin through the process of tagmentation, the fragmenting and tagging of DNA by the same enzyme, to produce libraries with which sequencing can determine chromatin accessibility across an entire genome. This tagmentation process is mediated by the hyperactive Tn5 transposase, which only cuts open regions of chromatin due to nucleosomic steric hindrance. As it cuts, the Tn5 transposase also inserts sequencing adapters that allow for rapid library construction by PCR and next-generation sequencing of genome-wide accessible chromatin1,2.
ATAC-seq has become the preferred method to determine regions of chromatin accessibility due to the relatively simple and fast protocol, quality and range of information that can be determined from its results, and small amount of starting material required. Compared to DNase-seq3 (which also measures genome-wide chromatin accessibility), MNase-seq4 (which determines nucleosome positions in open genome regions), and the formaldehyde-mediated FAIRE-seq5, ATAC-seq is faster, cheaper, and more reproducible1. It is also more sensitive, working with starting material of as few as 500 nuclei, compared to the 50 million nuclei required for DNase-seq3. ATAC-seq also has the ability to provide more information about chromatin architecture than other methods, including regions of transcription factor binding, nucleosome positioning, and open chromatin regions1. Effective, single-cell ATAC-seq protocols have been validated, providing information on chromatin architecture at the single-cell level6,7.
ATAC-seq has been used to characterize chromatin architecture across a wide spectrum of research and cells types, including plants8, humans9, and many other organisms. It has also been critical in identifying epigenetic regulation of disease states7. However, the most widely used ATAC-seq protocol includes the major drawback of contamination sequencing reads from mitochondrial DNA. In some data sets, this contamination level can be as high as 60% of sequencing results1. There is a concerted effort in the field to reduce these contaminating mitochondrial reads in order to allow for the more efficient application of ATAC-seq7,10,11.&#160;Here we present an improved ATAC-seq protocol that reduces the mitochondrial DNA contamination rate to just 3%, allowing reduction of around 50% in sequencing costs10. This is made possible by a streamlined process of CD4+ lymphocyte isolation and activation and an improved lysis buffer that is critical in minimizing mitochondrial DNA contamination.
This modifiedATAC-seq protocol has been validated with a wide range of primary cells, including human primary peripheral blood mononuclear cells (PBMCs)10, human primary monocytes, and mouse dendritic cells (unpublished). It has also been used successfully to interrogate melanoma cell lines in a clustered regularly interspaced short palindromic repeats (CRISPR) screen of non-coding elements11. Additionally, the data analysis package described in this protocol and provided on GitHub provides new and experienced researchers with tools to analyze ATAC-seq data. ATAC-seq is the most effective assay to map chromatin accessibility across an entire genome, and modifications to the existing protocol that are introduced here will allow researchers to produce high-quality data with low mitochondrial DNA contamination, reducing sequencing costs and improving ATAC-seq throughput.

<table>
	<tbody>
		<tr>
			<td>1X PBS, Sterile</td>
			<td>Gibco</td>
			<td>10010023</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>5810/5810&#160;R Swing Bucket Refrigerated Centrifuge with 50 mL, 15 mL, and 1.5 mL Tube Buckets</td>
			<td>Eppendorf</td>
			<td>22625501</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>96 Well Round Bottom Plate</td>
			<td>Thermo Scientific</td>
			<td>163320</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>Agilent 4200 Tape Station System</td>
			<td>Agilent</td>
			<td>G2991AA</td>
			<td>Suggested for quality assessment.</td>
		</tr>
		<tr>
			<td>Cryotubes</td>
			<td>Thermo Scientific</td>
			<td>374081</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>Sigma</td>
			<td>D8418</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>Dynabeads Human T-Activator CD3/CD28</td>
			<td>Invitrogen Life Technologies</td>
			<td>11131D</td>
			<td>Critical Component</td>
		</tr>
		<tr>
			<td>Dynabeads Untouched Human CD4 T Cells Kit</td>
			<td>Invitrogen Life Technologies</td>
			<td>11346D</td>
			<td>Critical Component</td>
		</tr>
		<tr>
			<td>Dynamagnet</td>
			<td>Invitrogen Life Technologies</td>
			<td>12321D</td>
			<td>Critical Component</td>
		</tr>
		<tr>
			<td>FCS</td>
			<td>Gemini Bio Products</td>
			<td>100-500</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>High Sensitivity DNA Kit</td>
			<td>Agilent</td>
			<td>50674626</td>
			<td>Suggested for quality assessment.</td>
		</tr>
		<tr>
			<td>Magnesium Chloride, Hexahydrate, Molecular Biology Grade</td>
			<td>Sigma</td>
			<td>M2393</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>MinElute PCR Purification Kit (Buffer PB, Buffer PE, Elution Buffer)</td>
			<td>Qiagen</td>
			<td>28004</td>
			<td>Critical Component</td>
		</tr>
		<tr>
			<td>Mr. Frosty</td>
			<td>Thermo Scientific</td>
			<td>5100-0001</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>NaCl, Molecular Biology Grade</td>
			<td>Sigma</td>
			<td>S3014</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>NEBNext High Fidelity 2X PCR Master Mix</td>
			<td>New England BioLabs</td>
			<td>M0541</td>
			<td>Critical Component</td>
		</tr>
		<tr>
			<td>Nextera DNA Library Preparation Kit (2X TD Buffer, Tn5 Enzyme)</td>
			<td>Illumina</td>
			<td>FC1211030</td>
			<td>Critical Component</td>
		</tr>
		<tr>
			<td>Nuclease Free Sterile dH20</td>
			<td>Gibco</td>
			<td>10977015</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>Polysorbate 20 (Tween20)</td>
			<td>Sigma</td>
			<td>P9416</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>PowerUp SYBR Green Master Mix</td>
			<td>Applied Biosystems</td>
			<td>A25780</td>
			<td>Critical Component</td>
		</tr>
		<tr>
			<td>Precision Water Bath</td>
			<td>Thermo Scientific</td>
			<td>TSGP02</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>QIAquick PCR Purification Kit</td>
			<td>Qiagen</td>
			<td>28104</td>
			<td>Critical Component</td>
		</tr>
		<tr>
			<td>Qubit dsDNA HS Assay Kit</td>
			<td>Invitrogen Life Technologies</td>
			<td>Q32851</td>
			<td>Suggested for quality assessment.</td>
		</tr>
		<tr>
			<td>Qubit FlouroMeter</td>
			<td>Invitrogen Life Technologies</td>
			<td>Q33226</td>
			<td>Suggested for quality assessment.</td>
		</tr>
		<tr>
			<td>Rosette Sep Human CD4+ Density Medium</td>
			<td>Stem Cell Technologies</td>
			<td>15705</td>
			<td>Critical Component</td>
		</tr>
		<tr>
			<td>Rosette Sep Human CD4+ Enrichment Cocktail</td>
			<td>Stem Cell Technologies</td>
			<td>15022</td>
			<td>Critical Component</td>
		</tr>
		<tr>
			<td>RPMI-1640</td>
			<td>Gibco</td>
			<td>11875093</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>Sterile Resevoir</td>
			<td>Thermo Scientific</td>
			<td>8096-11</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>T100 Thermocycler with Heated Lid</td>
			<td>BioRad</td>
			<td>1861096</td>
			<td>Can use other comparable products.</td>
		</tr>
		<tr>
			<td>Tris-HCL</td>
			<td>Sigma</td>
			<td>T5941</td>
			<td>Can use other comparable products.</td>
		</tr>
	</tbody>
</table>

atac-seq assay with low mitochondrial dna contamination from primary human cd4+ t lymphocytes

ATAC-seq has become a widely used methodology in the study of epigenetics due to its rapid and simple approach to mapping genome-wide accessible chromatin. In this paper we present an improved ATAC-seq protocol that reduces contaminating mitochondrial DNA reads. While previous ATAC-seq protocols have struggled with an average of 50% contaminating mitochondrial DNA reads, the optimized&#160;lysis buffer introduced in this protocol reduces mitochondrial DNA contamination to an average of 3%. This improved ATAC-seq protocol allows for a near 50% reduction in the sequencing cost. We demonstrate how these high-quality ATAC-seq libraries can be prepared from activated CD4+ lymphocytes, providing step-by-step instructions from CD4+ lymphocyte isolation from whole blood through data analysis. This improved ATAC-seq protocol has been validated in a wide range of cell types and will be of immediate use to researchers studying chromatin accessibility.

From 15 mL of fresh whole blood, this protocol generates an average of 1 million CD4+ T cells. These can be frozen for later processing or used immediately. Viability of the CD4+ T cells, fresh or thawed, was consistently &#62;95%. This method of CD4+ T cell isolation allows for flexibility in source material and collection time. This improved ATAC-seq protocol produces a final library of greater than 1 ng/&#181;L for sequencing. Quality control performed using commercially available syst...

Watch this Scientific Journal Video about ATAC-seq Assay with Low Mitochondrial DNA Contamination from Primary Human CD4+ T Lymphocytes at JoVE.com

ATAC-seq Assay with Low Mitochondrial DNA Contamination from Primary Human CD4+ T Lymphocytes

Here, we present a protocol to perform an assay for transposase-accessible chromatin sequencing (ATAC-seq) on activated CD4+ human lymphocytes. The protocol has been modified to minimize contaminating mitochondrial DNA reads from 50% to 3% through the introduction of a new lysis buffer.

ATAC-seq has become a widely used methodology in the study of epigenetics due to its rapid and simple approach to mapping genome-wide accessible ...

This modified ATAC-seq protocol introduces a new lysis buffer that decreases contaminating mitochondrial reads from 50%to less than 3%The decreased mitochondrial contamination will allow researchers to perform more efficient ATAC-seq with a 50%decrease in sequencing costs. We have validated this new ATAC-seq protocol in human primary PBMCs, human primary monocytes, mouse dendritic cells, and melanoma cell lines. We believe it will be effective in a wide range of cell types.Minimizing sample loss during the cell activation and selection process is critical for obtaining high-quality results with ATAC-seq. We will demonstrate how to handle small numbers of cells from precious samples using basic laboratory equipment. To begin, thaw one vial of previously isolated CD4+T cells in a 37-degree Celsius water bath until the ice has just melted.Then gently transfer the cells to a 15-milliliter conical tube containing nine milliliters of pre-warmed complete RPMI. Centrifuge the cells at 1, 500 times G, and four degrees Celsius, for six minutes. Then discard the supernatant, and gently resuspend the pellet in two milliliters of complete RPMI.After repeating the centrifugation, discard the supernatant, and gently resuspend the cells in 0.5 milliliters of complete RPMI. Use a hemocytometer to count the cells. Using complete RPMI, adjust the cell suspension density to plate 50, 000 CD4+cells in 200 microliters per well of a 96-well round-bottom plate.Then, to prepare magnetic beads, aliquot 12.5 microliters of Human T-Activator CD3/CD28 beads per ATAC-seq sample to a 1.5 milliliter tube. Add one milliliter of 1x PBS to the tube, and place it on a magnet for one minute to wash the beads. Carefully remove and discard the clear supernatant, and remove the tube from the magnet.Resuspend the beads in 13 microliters of complete RPMI per ATAC-seq sample. To activate the CD4+T cells with the adjusted concentration, collect 500, 000 cells in 2.1 milliliters of complete RPMI medium in a 15-milliliter conical tube. Add 12.5 microliters of Human T-Activator beads, prepared and washed in previous steps, and gently mix by inverting the tube.Then gently transfer the cells, with beads, to a sterile reservoir. Using a multi-channel pipette, plate 200 microliters of cells with beads per well of a round-bottom 96-well plate, and incubate in a 37-degree Celsius, 5%CO2 incubator for 48 hours. After complete incubation, centrifuge the plate at 423 times G, and room temperature, for eight minutes.Remove 100 microliters of medium from each well, and collect it in a conical tube before discarding, in order to confirm no bead loss. Then resuspend the cell pellet in the remaining 100 microliters of medium, and collect everything in a 1.5-milliliter tube. To isolate CD4+cells, add 50 microliters of pre-washed CD4 conjugated beads to 500, 000 cells in one milliliter of complete RPMI, and invert to mix.Incubate for 20 minutes at four degrees Celsius, while hand-flicking every six minutes to mix. Place the tube on the magnet for two minutes, until supernatant is clear, and then remove and discard. Remove the tube from the magnet.Wash the bead-bound cells by resuspending them in one milliliter of PBS, plus 2%FCS, and place the tube back on the magnet for one minute. Discard the clear supernatant, and repeat this process for a total of three washes. After the final wash, place the tube on the magnet for one minute.Remove it, discard the supernatant, and place the pellet on ice. Next, to perform nuclei isolation, resuspend the beads and cells in 50 microliters of cold lysis buffer, and centrifuge immediately at 500 G, four degrees Celsius, for 10 minutes. Remove and discard the supernatant.To perform the transposase reaction, resuspend the isolated nuclei pellet with 50 microliters of Tn5 transposase mix. Incubate in a thermocycler for 30 minutes at 37 degrees Celsius, with the lid set to 40 degrees Celsius, and then hold at four degrees Celsius when complete. Immediately after thermocycling, perform a quick bench-top centrifuge spin-down.Place the tube on the magnet for one minute to remove the beads from the product. Without removing the tube from the magnet, transfer the clear supernatant to a DNA purification column. Wash the column once with 250 microliters of PB buffer, and twice with 750 microliters of PE buffer.Then add 10 microliters of elution buffer to elute the sample. Set up the initial PCR amplification reaction in a nuclease-free PCR tube. Place the PCR tube into the thermocycler, and run the PCR amplification program.Then complete the final PCR amplification of the remaining 45 microliters of PCR reaction, as described in the manuscript. Place the PCR tube in the thermocycler and run the program. After complete amplification, purify the libraries using a PCR cleanup kit, following the manufacturer's protocol, eluting in 25 microliters of the elution buffer.Sequence the prepared libraries on a next-generation sequencer to an average read depth of 42 million reads per sample. This improved ATAC-seq protocol produced a final library of greater than one nanogram per microliter for sequencing. Quality control showed DNA fragments between 200 and 1, 000 base pairs, and further sequencing was performed with these high-quality libraries.Libraries prepared following this protocol showed only 3%mitochondrial contamination. The high percentage of usable reads is sufficiently constant across biological replicates. This protocol provided highly reproducible results across technical replicates, as well as biological replicates.Additionally, this protocol took 48 hours, rather than one week or more as previously described, resulting in consistent and efficient activation, as demonstrated by reproducible sequencing results. Furthermore, predicted ATAC-seq peaks were accurately called by the analysis pipeline. Sequencing result analysis revealed clear changes in chromatin state during human T cell activation.Differentially accessible regions of open chromatin were identified between six samples before and 48 hours after activation. Make sure the nuclei lysis reaction is performed with chilled reagents and materials, in order to maximize the recovery of intact nuclei. Our modified nuclei lysis buffer is gentler on the cells, and minimizes contaminating mitochondrial DNA.We look forward to this modified lysis buffer being applied to single-nuclei ATAC-seq as well. We know this protocol will allow researchers to produce higher-quality ATAC-seq data at a decreased cost, helping to forward the epigenetic field. The protocol is straightforward, rapid, and does not require any hazardous reagents or instruments, making it easily accessible for those new to ATAC-seq.

atac-seq-assay-with-low-mitochondrial-dna-contamination-from-primary

Research

JoVE Journal

Genetics

Design and Use of a Low Cost, Automated Morbidostat for Adaptive Evolution of Bacteria Under Antibiotic Drug Selection

We describe a low cost, configurable morbidostat for characterizing the evolutionary pathway of antibiotic resistance. The morbidostat is a bacterial culture device that continuously monitors bacterial growth and dynamically adjusts the drug concentration to constantly challenge the bacteria as they evolve to acquire drug resistance. The device features a working volume of ~10 ml and is fully automated and equipped with optical density measurement and micro-pumps for medium and drug delivery. To validate the platform, we measured the stepwise acquisition of trimethoprim resistance in Escherichia coli MG 1655, and integrated the device with a multiplexed microfluidic platform to investigate cell morphology and antibiotic susceptibility. The approach can be up-scaled to laboratory studies of antibiotic drug resistance, and is extendible to adaptive evolution for strain improvements in metabolic engineering and other bacterial culture experiments.

We describe a low cost, configurable morbidostat that enables the characterization of antibiotic drug resistance by dynamically adjusting the drug concentration. The device can be integrated with a multiplexed microfluidic platform. The approach can be scaled up for laboratory antibiotic drug resistance studies.

We describe a low cost, configurable morbidostat for characterizing the evolutionary pathway of antibiotic resistance. The morbidostat is a bacterial ...

In Situ Labeling of Mitochondrial DNA Replication in Drosophila Adult Ovaries by EdU Staining

The mitochondrial genome is inherited exclusively through the maternal line. Understanding of how the mitochondrion and its genome are proliferated and transmitted from one generation to the next through the female oocyte is of fundamental importance. Because of the genetic tractability, and the elegant, ordered simplicity by which oocyte development proceeds, Drosophila oogenesis has become an invaluable system for mitochondrial study. An EdU (5-ethynyl-2&#180;-deoxyuridine) labeling method was utilized to detect mitochondrial DNA (mtDNA) replication in Drosophila ovaries. This method is superior to the BrdU (5-bromo-2'-deoxyuridine) labeling method in that it allows for good structural preservation and efficient fluorescent dye penetration of whole-mount tissues.
Here we describe a detailed protocol for labeling replicating mitochondrial DNA in Drosophila adult ovaries with EdU. Some technical solutions are offered to improve the viability of the ovaries, maintain their health during preparation, and ensure high-quality imaging. Visualization of newly synthesized mtDNA in the ovaries not only reveals the striking temporal and spatial pattern of mtDNA replication through oogenesis, but also allows for simple quantification of mtDNA replication under various genetic and pharmacological perturbations.

In Situ Labeling of Mitochondrial DNA Replication in Drosophila Adult Ovaries by EdU Staining

Drosophila oogenesis continues to be exceptionally useful in the study of mitochondrial proliferation and inheritance. This manuscript describes a detailed protocol used to label the replicating mitochondrial DNA (mtDNA) in Drosophila adult ovaries with 5-ethynyl-2&#180;-deoxyuridine (EdU), which facilitates uncovering mechanisms associated with mitochondrial inheritance that were previously debatable.

The mitochondrial genome is inherited exclusively through the maternal line. Understanding of how the mitochondrion and its genome are proliferated and ...

Assessment of DNA Contamination in RNA Samples Based on Ribosomal DNA

One method extensively used for the quantification of gene expression changes and transcript abundances is reverse-transcription quantitative real-time PCR (RT-qPCR). It provides accurate, sensitive, reliable, and reproducible results. Several factors can affect the sensitivity and specificity of RT-qPCR. Residual genomic DNA (gDNA) contaminating RNA samples is one of them. In gene expression analysis, non-specific amplification due to gDNA contamination will overestimate the abundance of transcript levels and can affect the RT-qPCR results. Generally, gDNA is detected by qRT-PCR using primer pairs annealing to intergenic regions or an intron of the gene of interest. Unfortunately, intron/exon annotations are not yet known for all genes from vertebrate, bacteria, protist, fungi, plant, and invertebrate metazoan species.
Here we present a protocol for detection of gDNA contamination in RNA samples by using ribosomal DNA (rDNA)-based primers. The method is based on the unique features of rDNA: their multigene nature, highly conserved sequences, and high frequency in the genome. Also as a case study, a unique set of primers were designed based on the conserved region of ribosomal DNA (rDNA) in the Poaceae family. The universality of these primer pairs was tested by melt curve analysis and agarose gel electrophoresis. Although our method explains how rDNA-based primers can be applied for the gDNA contamination assay in the Poaceae family,&#160;it could be easily used to other prokaryote and eukaryote species

Here, we present a protocol for tracing genomic DNA (gDNA) contamination in RNA samples. The presented method utilizes primers specific for the internal transcribed spacer region (ITS) of ribosomal DNA (rDNA) genes. The method is suited for reliable and sensitive detection of DNA contamination in most eukaryotes and prokaryotes.

One method extensively used for the quantification of gene expression changes and transcript abundances is reverse-transcription quantitative real-time ...

High Fat Diet Feeding and High Throughput Triacylglyceride Assay in Drosophila Melanogaster

Heart disease is the number one cause of human death worldwide. Numerous studies have shown strong connections between obesity and cardiac malfunction in humans, but more tools and research efforts are needed to better elucidate the mechanisms involved. For over a century, the genetically highly tractable model of Drosophila has been instrumental in the discovery of key genes and molecular pathways that proved to be highly conserved across species. Many biological processes and disease mechanisms are functionally conserved in the fly, such as development (e.g., body plan, heart), cancer, and neurodegenerative disease. Recently, the study of obesity and secondary pathologies, such as heart disease in model organisms, has played a highly critical role in the identification of key regulators involved in metabolic syndrome in humans.
Here, we propose to use this model organism as an efficient tool to induce obesity, i.e., excessive fat accumulation, and develop an efficient protocol to monitor fat content in the form of TAGs accumulation. In addition to the highly conserved, but less complex genome, the fly also has a short lifespan for rapid experimentation, combined with cost-effectiveness. This paper provides a detailed protocol for High Fat Diet (HFD) feeding in Drosophila to induce obesity and a high throughput triacylglyceride (TAG) assay for measuring the associated increase in fat content, with the aim to be highly reproducible and efficient for large-scale genetic or chemical screening. These protocols offer new opportunities to efficiently investigate regulatory mechanisms involved in obesity, as well as provide a standardized platform for drug discovery research for rapid testing of the effect of drug candidates on the development or prevention of obesity, diabetes and related metabolic diseases.

High Fat Diet Feeding and High Throughput Triacylglyceride Assay in Drosophila Melanogaster

This is a high fat diet feeding protocol to induce obesity in Drosophila, a model for understanding fundamental molecular mechanisms implicated in lipotoxicity. It also provides a high throughput triacylglyceride assay for measuring fat accumulation in Drosophila and potentially other (insect) models under various dietary, environmental, genetic or physiological conditions.

Heart disease is the number one cause of human death worldwide. Numerous studies have shown strong connections between obesity and cardiac malfunction in ...

Mapping Genome-wide Accessible Chromatin in Primary Human T Lymphocytes by ATAC-Seq

Assay for Transposase-Accessible Chromatin with high-throughput sequencing (ATAC-seq) is a method used for the identification of open (accessible) regions of chromatin. These regions represent regulatory DNA elements (e.g., promoters, enhancers, locus control regions, insulators) to which transcription factors bind. Mapping the accessible chromatin landscape is a powerful approach for uncovering active regulatory elements across the genome. This information serves as an unbiased approach for discovering the network of relevant transcription factors and mechanisms of chromatin structure that govern gene expression programs. ATAC-seq is a robust and sensitive alternative to DNase I hypersensitivity analysis coupled with next-generation sequencing (DNase-seq) and formaldehyde-assisted isolation of regulatory elements (FAIRE-seq) for genome-wide analysis of chromatin accessibility and to the sequencing of micrococcal nuclease-sensitive sites (MNase-seq) to determine nucleosome positioning. We present a detailed ATAC-seq protocol optimized for human primary immune cells i.e. CD4+ lymphocytes (T helper 1 (Th1) and Th2 cells). This comprehensive protocol begins with cell harvest, then describes the molecular procedure of chromatin tagmentation, sample preparation for next-generation sequencing, and also includes methods and considerations for the computational analyses used to interpret the results. Moreover, to save time and money, we introduced quality control measures to assess the ATAC-seq library prior to sequencing. Importantly, the principles presented in this protocol allow its adaptation to other human immune and non-immune primary cells and cell lines. These guidelines will also be useful for laboratories which are not proficient with next-generation sequencing methods.

Assay for Transposase-Accessible Chromatin coupled with high-throughput sequencing (ATAC-seq) is a genome-wide method to uncover accessible chromatin. This is a step-by-step ATAC-seq protocol, from molecular to the final computational analysis, optimized for human lymphocytes (Th1/Th2). This protocol can be adopted by researchers without prior experience in next-generation sequencing methods.

Assay for Transposase-Accessible Chromatin with high-throughput sequencing (ATAC-seq) is a method used for the identification of open (accessible) regions ...

Methodology for Accurate Detection of Mitochondrial DNA Methylation

Quantification of DNA methylation can be achieved using bisulfite sequencing, which takes advantage of the property of sodium bisulfite to convert unmethylated cytosine into uracil, in a single-stranded DNA context. Bisulfite sequencing can be targeted (using PCR) or performed on the whole genome and provides absolute quantification of cytosine methylation at the single base-resolution. Given the distinct nature of nuclear- and mitochondrial DNA, notably in the secondary structure, adaptions of bisulfite sequencing methods for investigating cytosine methylation in mtDNA should be made. Secondary and tertiary structure of mtDNA can indeed lead to bisulfite sequencing artifacts leading to false-positives due to incomplete denaturation poor access of bisulfite to single-stranded DNA. Here, we describe a protocol using an enzymatic digestion of DNA with BamHI coupled with bioinformatic analysis pipeline to allow accurate quantification of cytosine methylation levels in mtDNA. In addition, we provide guidelines for designing the bisulfite sequencing primers specific to mtDNA, in order to avoid targeting undesirable NUclear MiTochondrial segments (NUMTs) inserted into the nuclear genome.

Here, we present a protocol to allow accurate quantification of mitochondrial DNA (mtDNA) methylation. In this protocol, we describe an enzymatic digestion of DNA with BamHI coupled with a bioinformatic analysis pipeline which can be used to avoid overestimation of mtDNA methylation levels caused by the secondary structure of mtDNA.

Quantification of DNA methylation can be achieved using bisulfite sequencing, which takes advantage of the property of sodium bisulfite to convert ...

Isolating, Sequencing and Analyzing Extracellular MicroRNAs from Human Mesenchymal Stem Cells

Extracellular and circulating RNAs (exRNA) are produced by many cell types of the body and exist in numerous bodily fluids such as saliva, plasma, serum, milk and urine. One subset of these RNAs are the posttranscriptional regulators &#8211; microRNAs (miRNAs). To delineate the miRNAs produced by specific cell types, in vitro culture systems can be used to harvest and profile exRNAs derived from one subset of cells. The secreted factors of mesenchymal stem cells are implicated in alleviating numerous diseases and is used as the in vitro model system here. This paper describes the process of collection, purification of small RNA and library generation to sequence extracellular miRNAs. ExRNAs from culture media differ from cellular RNA by being low RNA input samples, which calls for optimized procedures. This protocol provides a comprehensive guide to small exRNA sequencing from culture media, showing quality control checkpoints at each step during exRNA purification and sequencing.

This protocol demonstrates how to purify extracellular microRNAs from cell culture media for small RNA library construction and next generation sequencing. Various quality control checkpoints are described to allow readers to understand what to expect when working with low input samples like exRNAs.

Extracellular and circulating RNAs (exRNA) are produced by many cell types of the body and exist in numerous bodily fluids such as saliva, plasma, serum, ...

Lentiviral Mediated Gene Silencing in Human Pseudoislet Prepared in Low Attachment Plates

Various genetic tools are available to modulate genes in pancreatic islets of rodents to dissect function of islet genes for diabetes research. However, the data obtained from rodent islets are often not fully reproduced in or applicable to human islets due to well-known differences in islet structure and function between the species. Currently, techniques that are available to manipulate gene expression of human islets are very limited. Introduction of transgene into intact islets by adenovirus, plasmid, and oligonucleotides often suffers from low efficiency and high toxicity. Low efficiency is especially problematic in gene downregulation studies in intact islets, which require high efficiency. It has been known that enzymatically-dispersed islet cells reaggregate in culture forming spheroids termed pseudoislets. Size-controlled reaggregation of human islet cells creates pseudoislets that maintain dynamic first phase insulin secretion after prolonged culture and provide a window to efficiently introduce lentiviral short hairpin RNA (shRNA) with low toxicity. Here, a detailed protocol for the creation of human pseudoislets after lentiviral transduction using two commercially available multiwell plates is described. The protocol can be easily performed and allows for efficient downregulation of genes and assessment of dynamism of insulin secretion using human islet cells. Thus, human pseudoislets with lentiviral mediated gene modulation provide a powerful and versatile model to assess gene function within human islet cells.

A protocol to create gene modified human pseudoislets from dispersed human islet cells that are transduced by lentivirus carrying short hairpin RNA (shRNA) is presented. This protocol utilizes readily available enzyme and culture vessels, can be performed easily, and produces genetically modified human pseudoislets suitable for functional and morphological studies.

Various genetic tools are available to modulate genes in pancreatic islets of rodents to dissect function of islet genes for diabetes research. However, ...

Tumorsphere Derivation and Treatment from Primary Tumor Cells Isolated from Mouse Rhabdomyosarcomas

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Although significant efforts have enabled the identification of common mutations associated with RMS and allowed discrimination of different RMS subtypes, major challenges still exist for the development of novel treatments to further improve prognosis. Although identified by the expression of myogenic markers, there is still significant controversy over whether RMS has myogenic or non-myogenic origins, as the cell of origin is still poorly understood. In the present study, a reliable method is provided for the tumorsphere assay for mouse RMS. The assay is based on functional properties of tumor cells and allows the identification of rare populations in the tumor with tumorigenic functions. Also described are procedures for testing recombinant proteins, integrating transfection protocols with the tumorsphere assay, and evaluating candidate genes involved in tumor development and growth. Described further is a procedure for allograft transplantation of tumorspheres into recipient mice to validate tumorigenic function in vivo. Overall, the described method allows reliable identification and testing of rare RMS tumorigenic populations that can be applied to RMS arising in different contexts. Finally, the protocol can be utilized as a platform for drug screening and future development of therapeutics.

This protocol describes a reproducible method for isolation of mouse rhabdomyosarcoma primary cells, tumorsphere formation and treatment, and allograft transplantation starting from tumorspheres cultures.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Although significant efforts have enabled the identification of common ...

Microsatellite DNA Genotyping and Flow Cytometry Ploidy Analyses of Formalin-fixed Paraffin-embedded Hydatidiform Molar Tissues

Hydatidiform mole (HM) is an abnormal human pregnancy characterized by excessive trophoblastic proliferation and abnormal embryonic development. There are two types of HM based on microscopic morphological evaluation, complete HM (CHM) and partial HM (PHM). These can be further subdivided based on the parental contribution to the molar genomes. Such characterization of HM, by morphology and genotype analyses, is crucial for patient management and for the fundamental understanding of this intriguing pathology. It is well documented that morphological analysis of HM is subject to wide interobserver variability and is not sufficient on its own to accurately classify HM into CHM and PHM and distinguish them from hydropic non-molar abortions. Genotyping analysis is mostly performed on DNA and tissues from formalin-fixed paraffin-embedded (FFPE) products of conception, which have less than optimal quality and may consequently lead to wrong conclusions. In this article, detailed protocols for multiplex genotyping and flow cytometry analyses of FFPE molar tissues are provided, along with the interpretation of the results of these methods, their troubleshooting, and integration with the morphological evaluation, p57KIP2 immunohistochemistry, and fluorescence in situ hybridization (FISH) to reach a correct and robust diagnosis. Here, the authors share the methods and lessons learned in the past 10 years from the analysis of approximately 400 products of conception.

Hydatidiform moles are abnormal human pregnancies with heterogeneous aetiologies that can be classified according to their morphological features and parental contribution to the molar genomes. Here, protocols of multiplex microsatellite DNA genotyping and flow cytometry of formalin-fixed paraffin-embedded molar tissues are described in detail, together with results&#8217; interpretation and integration.

Hydatidiform mole (HM) is an abnormal human pregnancy characterized by excessive trophoblastic proliferation and abnormal embryonic development. There are ...