Name: comprehensive dna methylation analysis using a methyl-cpg-binding domain capture-based method in chronic lymphocytic leukemia patients
Uploaded: 2017-06-16T13:00:00
Description: Watch this Scientific Journal Video about Comprehensive DNA Methylation Analysis Using a Methyl-CpG-binding Domain Capture-based Method in Chronic Lymphocytic Leukemia Patients at JoVE.com

This study was supported by the Swedish Research Council, the Swedish Cancer Society, the Knut and Alice Wallenberg Foundation (KAW), and FoU V&#228;straG&#246;talandsregionen.

The ethical approval for collecting the CLL samples is from 2007-05-21, with the following registration number: EPN Gbg dnr 239/07. All CLL patients were diagnosed according to recently revised criteria8, and the samples were collected at the time of diagnosis. The patients in the study were included from different hematology departments in the western part of Sweden after written consent had been obtained. Only CLL peripheral blood mononuclear cell (PBMC) samples with a tumor percentage of leukem...

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MBD-seq is a cost-effective, immunoprecipitation-based technique that can be used to study methylation patterns with complete genome-wide coverage. Both MeDIP seq (methylated DNA immunoprecipitation followed by sequencing) and MBD-seq result in the enrichment of CpG-rich methylated DNA. However, MBD-seq shows more affinity towards binding to highly CpG-rich regions when compared to MeDIP seq19. Using a methyl-binding enrichment kit, one can fractionate the DNA into high-CpG- and low-CpG-rich regio...

The use of next-generation sequencing techniques to analyze global DNA methylation profiles has been increasingly popular during recent years. Genome-wide methylation assays, including microarray- and non-microarray-based methods, were developed based on the following: the bisulfite conversion of genomic DNA, methylation-sensitive restriction enzyme digestions, and the immunoprecipitation of methylated DNA using methyl CpG-specific antibodies.
Aberrant DNA methylation is one of the hallmarks of leukemia and lymphomas, includingchronic lymphocytic leukemia (CLL). Earlier, several groups including ours characterized the DNA methylation profiles of different CLL prognostic subgroups and normal, healthy B-cell controls using the bisulfite conversion of genomic DNA, followed by micro-array-based methods or whole-genome sequencing1,2,3,4. The bisulfite conversion of genomic DNA leads to the deamination of unmodified cytosines to uracil, leaving the modified methylated cytosines in the genome. Once converted, the methylation status of the DNA can be determined by PCR amplification and sequencing using different quantitative or qualitative methods, such as micro-array-based or whole-genome bisulfite sequencing (WGBS). Although bisulfite conversion-based methods have many advantages and are widely used in different cancer types to analyze DNA methylation levels, there are a few drawbacks associated with this technique. WGBS sequencing allows single-base-pair resolution with lower amounts of DNA and is the best suitable option for analyzing a large number of samples. However, this method fails to differentiate the modifications between the 5 mC and 5 hmC levels in the genome5,6. Additionally, microarray-based methods do not offer complete coverage of the genome.
In a recent study from our laboratory7, immunoprecipitation based methods, rather than bisulfite conversion, were used to identify highly CpG-rich, differentially methylated regions on a global scale in CLL patients and normal healthy controls. Inmethyl-CpG-binding domain (MBD)next-generation sequencing (MBD-seq), the enrichment of double-stranded fragmented DNA depends upon the degree of CpG methylation. This method can overcome the drawbacks of the bisulfite conversion method and can also provide genome-wide coverage of CpG methylation in an unbiased and PCR-independent manner. Additionally, unlike bisulfite conversion-based microarray methods, MBD-seq can be used to analyze the methylation status of repetitive elements, such as long interspersed nuclear elements (LINEs), short interspersed nuclear elements (SINEs), long terminal repeats (LTRS), etc. However, compared to bisulfite conversion methods, an MBD-seq protocol requires a relatively large amount of input DNA. Also, the quality of the sequencing reads and the data depend on the specificity, affinity, and quality of the antibodies used.
The current study explains a detailed MBD-seq protocol to enrich methylated DNA for next-generation sequencing. It uses a commercial methylated DNA binding enrichment kit (listed in the Materials Table), as well as a computational pipeline to visualize and interpret methylation sequencing data to identify CLL-specific hyper- and hypomethylated regions compared to normal healthy controls. Basically, this method makes use of the ability of the MBD of the human MBD2 protein interaction with methylated CpGs to extract DNA enriched with methylated CpGs, and this is followed by the high-throughput sequencing of methylated DNA.

<table border="0" cellpadding="0" cellspacing="0" width="626">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Dneasy Blood and tissue kit</td>
			<td style="width:124px;">Qaigen</td>
			<td style="width:119px;">69504</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Lymphoprep solution</td>
			<td style="width:124px;">A X I S-S H I E L D</td>
			<td style="width:119px;">1114544</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Nano drop 2000</td>
			<td style="width:124px;">Thermo Fischersceintific</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="51">
			<td height="51" style="height:51px;width:216px;">TE buffer PH 8</td>
			<td style="width:124px;">Sigma aldrich</td>
			<td style="width:119px;">93283</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Bioruptor standard sonication device</td>
			<td style="width:124px;">Diagenode</td>
			<td style="width:119px;">UCD-200</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">TPX bioruptor tubes 1.5ml</td>
			<td style="width:124px;">Diagenode</td>
			<td style="width:119px;">C30010010-300</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">3 M Sodium acetate</td>
			<td style="width:124px;">Diagenode</td>
			<td>C03030002</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">E-gel iBase safe imager combo kit</td>
			<td style="width:124px;">Thermo Fischersceintific</td>
			<td style="width:119px;">G6465EU</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">E-gel 2% Agarose gels</td>
			<td style="width:124px;">Thermo Fischersceintific</td>
			<td style="width:119px;">G441002</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Methylminer Methylated DNA enrichment kit</td>
			<td style="width:124px;">Thermo Fischersceintific</td>
			<td style="width:119px;">ME10025</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Labquake Tube Shaker/Rotators</td>
			<td style="width:124px;">Thermo Fischersceintific</td>
			<td style="width:119px;">415110</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dynal MPC-S</td>
			<td style="width:124px;">Thermo Fischersceintific</td>
			<td style="width:119px;">A13346</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Vortex mixer</td>
			<td style="width:124px;">VWR</td>
			<td style="width:119px;">12620-848</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Absolute Ethanol</td>
			<td style="width:124px;">Any company</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">70% Ethanool</td>
			<td style="width:124px;">Any company</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DNAse free water</td>
			<td style="width:124px;">Milli Q</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">DNA precipitant (3M sodium acetate)</td>
			<td style="width:124px;">Diagenode</td>
			<td style="width:119px;">C03030002</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Safe seal 1.5ml eppendorf tubes</td>
			<td style="width:124px;">Eppendorf</td>
			<td style="width:119px;">4036-3204</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Qubit dsDNA HS Assay Kit</td>
			<td style="width:124px;">Thermo Fischersceintific</td>
			<td style="width:119px;">Q32851</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Qubit 0.5ml tubes</td>
			<td style="width:124px;">Thermo Fischersceintific</td>
			<td style="width:119px;">Q32856</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Qubit</td>
			<td style="width:124px;">Thermo Fischersceintific</td>
			<td style="width:119px;">Q32866</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:216px;">Illumina Hiseq2000 Platform</td>
			<td style="width:124px;">Illumina</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:216px;">Water&#160; Bath</td>
			<td style="width:124px;">Grant</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:216px;">Heat block</td>
			<td style="width:124px;">grant</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:216px;">Tube rotater</td>
			<td style="width:124px;">Labquake</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
	</tbody>
</table>

comprehensive dna methylation analysis using a methyl-cpg-binding domain capture-based method in chronic lymphocytic leukemia patients

The role of long noncoding RNAs (lncRNAs) in cancer is coming to the forefront due to growing interest in understanding their mechanistic functions during cancer development and progression. Despite this, the global epigenetic regulation of lncRNAs and repetitive sequences in cancer has not been well investigated, particularly in chronic lymphocytic leukemia (CLL). This study focuses on a unique approach: the immunoprecipitation-based capture of double-stranded, methylated DNA fragments using methyl-binding domain (MBD) proteins, followed by next-generation sequencing (MBD-seq). CLL patient samples belonging to two prognostic subgroups (5 IGVH mutated samples + 5 IGVH unmutated samples) were used in this study. Analysis revealed 5,800 hypermethylated and 12,570 hypomethylated CLL-specific differentially methylated genes (cllDMGs) compared to normal healthy controls. Importantly, these results identified several CLL-specific, differentially methylated lncRNAs, repetitive elements, and protein-coding genes with potential prognostic value. This work outlines a detailed protocol for an MBD-seq and bioinformatics pipeline developed for the comprehensive analysis of global methylation profiles in highly CpG-rich regions using CLL patient samples. Finally, a protein-coding gene and an lncRNA were validated using pyrosequencing, which is a highly quantitative method to analyze CpG methylation levels to further corroborate the findings from the MBD-seq protocol.

MBD-seq was recently performed on CLL patients and matched, normal, healthy controls to identify CLL-specific differentially hyper- and hypomethylated genes7. The experimental and bioinformatic pipeline used for analyzing the data generated from CLL and normal healthy samples are shown in Figure 1A and 1B. These analyses identified several CLL-specific differentially methylated regions (cllDMRs), which were significant...

Watch this Scientific Journal Video about Comprehensive DNA Methylation Analysis Using a Methyl-CpG-binding Domain Capture-based Method in Chronic Lymphocytic Leukemia Patients at JoVE.com

Comprehensive DNA Methylation Analysis Using a Methyl-CpG-binding Domain Capture-based Method in Chronic Lymphocytic Leukemia Patients

This work describes an optimized methyl-CpG-binding domain (MBD) sequencing protocol and a computational pipeline to identify differentially methylated CpG-rich regions in chronic lymphocytic leukemia (CLL) patients.

The role of long noncoding RNAs (lncRNAs) in cancer is coming to the forefront due to growing interest in understanding their mechanistic functions during ...

The overall goal of this procedure is to study global methylation profiling and identify differentially methylated CpG-rich regions in chronic lymphocytic leukemia patients using next-generation sequencing. This method can help answer key questions in the epigenetics field such as identification of the potential CLL-specific signature genes disease pathogenesis, and prognosis. The main advantage of this technique is that it provides complete genome-wide coverage of CpG methylation in an unbiased and PCR-independent manner.To begin, use a commercially available DNA extraction kit to isolate genomic DNA from the patient and normal peripheral blood mononuclear cell samples according to the manufacturer's protocol. After quantifying the genomic DNA as described in the text protocol, dilute 5 micrograms of genomic DNA from each sample, to a total of 200 microliters using TE buffer, giving a final concentration of 25 nanograms per microliter. Next, perform sonication in specially-designed tubes, using a sonicator, for a total of 30 cycles of 30 seconds on and 30 seconds off.After every five cycles, briefly spin the tubes to collect the samples to the bottom. Check the sonication range for all samples using DNA electrophoresis as described in the text protocol. To prepare the magnetic streptavidin beads, first re-suspend them from the stock tube provided by the kit.Gently pipette the beads up and down to obtain a homogenous suspension. For each five micrograms of fragmented DNA sample, place 50 microliters of the beads into separate, clean and labeled 1.5-milliliter tubes. Add 50 microliters of 1X bead wash buffer to reach a final volume of 100 microliters.Place the tubes on a magnetic stand for one minute to allow all the magnetic beads to concentrate on the inner wall of the tube facing the magnet. Remove the liquid without touching the beads, using a 200 microliter pipette. Then, remove the tubes from the magnetic stand, add 250 microliters of 1X bead wash buffer, and mix the beads gently with a pipette.After repeating these steps at least four times for all samples, finally resuspend the samples in 250 microliters of 1X bead wash buffer. Keep the samples on ice. To bind the MBD-biotin protein to the washed beads, first add 35 microliters of protein to separate tubes and bring the total volume up to 250 microliters using 1X bead wash buffer.Add 250 microliters of diluted MBD protein to the 250 microliters of washed beads and leave them on end-to-end rotation at room temperature. After mixing the beads in protein for one hour, wash the protein-bound magnetic streptavidin beads by placing the tubes on the magnetic stand for one minute. Remove the liquid without touching the beads using a pipette.Then, add 250 microliters of 1X bead wash buffer and place the tubes on a rotation mixer for five minutes at room temperature. Repeat the washing step two more times before re-suspending the washed MBD-biotin beads in 200 microliters of 1X bead wash buffer, making the beads ready for methylated DNA capture. In a clean 1.5-milliliter DNase-free tube, add 100 microliters of milliliter bead wash buffer and 180 microliters of the fragmented genomic DNA.Bring the final volume to 500 microliters using DNase-free water. Add 380 microliters of DNase-free water to the remaining 20 liters of the fragmented genomic DNA. Freeze the samples to later process them further and use them as input DNA controls.Place the tubes containing washed MBD-biotin beads on a magnetic stand for one minute, and remove the liquid without disturbing the beads. Then, add 500 microliters of fragmented genomic DNA diluted in bead wash buffer. Seal all the tubes tightly with paraffin film and leave them overnight at 4 degrees Celsius on an end-to-end rotation stand at 8 to 10 rotations per minute.After the DNA and MBD bead binding reaction, place the tubes on the magnetic rack for one minute to concentrate all the beads on the inner wall of the tube. Remove the supernatant liquid with a pipette without touching the beads, and save this unbound DNA sample fraction on ice. Then add 200 microliters of 1X bead wash buffer to the beads and place the tubes on the rotating stand for three minutes at room temperature.After removing the liquid using the magnetic stand, repeat the wash another two times to remove the residual unbound DNA. After the final wash, add 200 microliters of high-salt elution buffer provided in the kit to elute the DNA. Then, place the tubes on the rotating stand for 15 minutes at room temperature.Following incubation, place them on the magnetic stand for one minute and use a pipette to carefully transfer the supernatant to a new, clean 1.5-milliliter tube. Next, add 200 microliters of high-salt elution buffer to the beads, and repeat the elution by rotating the tubes at room temperature for an additional 15 minutes. Add the second elute to the same tube containing the 200 microliters of the first elute.To precipitate the DNA, add one microliter of glycogen, 40 microliters of three molar sodium acetate, pH 5.2, and 800 microliters of ice-cold absolute ethanol to 400 microliters of eluted DNA. Also add the reagents to the previously frozen 400 microliters of input DNA control samples. Mix the tubes well by vortexing before incubating them at minus 80 degrees Celsius overnight.The next day, centrifuge the tubes at 12, 000 times g and 4 degrees Celsius for 30 minutes. Discard the supernatant carefully without disturbing the pellet. Then, add 500 microliters of 70%ethanol and vortex the tubes.After centrifuging the tubes again using the same conditions but for 15 minutes, remove the supernatant by carefully using a pipette. Then, centrifuge the tubes at maximum speed for one minute at room temperature, and remove the residual ethanol completely using a pipette tip. Air-dry the pellet for five minutes at room temperature.Finally, add 10 microliters of DNase-free water to the DNA pellet before proceeding to the methylated DNA quantification, MBD sequencing, and analysis as described in the text protocol. The analysis identified several differentially hyper-and hypomethylated regions enriched in CLL samples compared to normal controls. These differentially methylated regions were mapped to different classes of protein coding and noncoding genes.Finally, the data analysis showed significant overlap between the CLL-associated differentially methylated regions obtained from two different normal control comparisons. Here, all the CpG sites located in target regions of two differentially methylated genes were validated in a large number of CLL samples using pyrosequencing. The optimum range of sonication required for this method is illustrated here.This range of fragmented DNA is ideal and more suitable for next-generation sequencing purposes. Once mastered, this technique can be done in two days if it is done properly. While attempting this procedure, the crucial factors that affect the final DNA recovery are the quality and the amount of the input DNA used and the range of the fragmented DNA after sonication.We decided to use this method because it is the first CLL global methylation study that is based on the immunoprecipitation for enriching methylated DNA covering all the methylated regions across the genome. The implications of this technique extend towards prognosis or therapy because the identified differentially methylated signature genes could serve as global normal biomarkers and epigenetic targets for therapy. Following this procedure, the enriched methylated DNA can be used for other downstream applications like hybridizing or doing microarrays to easily compare the metalomes between two samples or disease entities using a fixed set of CpG sites present on the arrays.Finally, this is a cost-effective technique to analyze large number of patient samples for methylated sequences across the genome, including annotated sequences spanning protein-coding genes as well as non-annotated sequences spanning repetitive elements and long non-coding RNAs.

comprehensive-dna-methylation-analysis-using-methyl-cpg-binding

Research

JoVE Journal

Genetics

Determination of the Optimal Chromosomal Location(s) for a DNA Element in Escherichia coli Using a Novel Transposon-mediated Approach

The optimal chromosomal position(s) of a given DNA element was/were determined by transposon-mediated random insertion followed by fitness selection. In bacteria, the impact of the genetic context on the function of a genetic element can be difficult to assess. Several mechanisms, including topological effects, transcriptional interference from neighboring genes, and/or replication-associated gene dosage, may affect the function of a given genetic element. Here, we describe a method that permits the random integration of a DNA element into the chromosome of Escherichia coli and select the most favorable locations using a simple growth competition experiment. The method takes advantage of a well-described transposon-based system of random insertion, coupled with a selection of the fittest clone(s) by growth advantage, a procedure that is easily adjustable to experimental needs. The nature of the fittest clone(s) can be determined by whole-genome sequencing on a complex multi-clonal population or by easy gene walking for the rapid identification of selected clones. Here, the non-coding DNA region DARS2, which controls the initiation of chromosome replication in E. coli, was used as an example. The function of DARS2 is known to be affected by replication-associated gene dosage; the closer DARS2 gets to the origin of DNA replication, the more active it becomes. DARS2 was randomly inserted into the chromosome of a DARS2-deleted strain. The resultant clones containing individual insertions were pooled and competed against one another for hundreds of generations. Finally, the fittest clones were characterized and found to contain DARS2 inserted in close proximity to the original DARS2 location.

Determination of the Optimal Chromosomal Locations for a DNA Element in Escherichia coli Using a Novel Transposon-mediated Approach

Here, the power of a transposon-mediated random insertion of a non-coding DNA element was used to resolve its optimal chromosomal position.

The optimal chromosomal position(s) of a given DNA element was/were determined by transposon-mediated random insertion followed by fitness selection. In ...

Profiling DNA Replication Timing Using Zebrafish as an In Vivo Model System

DNA replication timing is an important cellular characteristic, exhibiting significant relationships with chromatin structure, transcription, and DNA mutation rates. Changes in replication timing occur during development and in cancer, but the role replication timing plays in development and disease is not known. Zebrafish were recently established as an in vivo model system to study replication timing. Here is detailed the protocols for using the zebrafish to determine DNA replication timing. After sorting cells from embryos and adult zebrafish, high-resolution genome-wide DNA replication timing patterns can be constructed by determining changes in DNA copy number through analysis of next generation sequencing data. The zebrafish model system allows for evaluation of the replication timing changes that occur in vivo throughout development, and can also be used to assess changes in individual cell types, disease models, or mutant lines. These methods will enable studies investigating the mechanisms and determinants of replication timing establishment and maintenance during development, the role replication timing plays in mutations and tumorigenesis, and the effects of perturbing replication timing on development and disease.

Profiling DNA Replication Timing Using Zebrafish as an In Vivo Model System

Zebrafish were recently used as an in vivo model system to study DNA replication timing during development. Here is detailed the protocols for using zebrafish embryos to profile replication timing. This protocol can be easily adapted to study replication timing in mutants, individual cell types, disease models, and other species.

DNA replication timing is an important cellular characteristic, exhibiting significant relationships with chromatin structure, transcription, and DNA ...

Candidate Gene Testing in Clinical Cohort Studies with Multiplexed Genotyping and Mass Spectrometry

Complex diseases are often underpinned by multiple common genetic variants that contribute to disease susceptibility. Here, we describe a cost-effective tag single nucleotide polymorphism (SNP) approach using a multiplexed genotyping assay with mass spectrometry, to investigate gene pathway associations in clinical cohorts. We investigate the food allergy candidate locus Interleukin13 (IL13) as an example. This method efficiently maximizes the coverage by taking advantage of shared linkage disequilibrium (LD) within a region. Selected LD SNPs are then designed into a multiplexed assay, enabling up to 40 different SNPs to be analyzed simultaneously, boosting cost-effectiveness. Polymerase chain reaction (PCR) is used to amplify the target loci, followed by single nucleotide extension, and the amplicons are then measured using matrix-assisted laser desorption/ionization-time of flight(MALDI-TOF) mass spectrometry. The raw output is analyzed with the genotype calling software, using stringent quality control definitions and cut-offs, and high probability genotypes are determined and output for data analysis.

Identification of genetic variants contributing to complex human disease allows us to identify novel mechanisms. Here, we demonstrate a multiplex genotyping approach to candidate genes or gene pathway analysis that maximizes the coverage at low cost and is amenable to cohort-based studies.

Complex diseases are often underpinned by multiple common genetic variants that contribute to disease susceptibility. Here, we describe a cost-effective ...

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 ...

Quantitative Analysis of Alternative Pre-mRNA Splicing in Mouse Brain Sections Using RNA In Situ Hybridization Assay

Alternative splicing (AS) occurs in more than 90% of human genes. The expression pattern of an alternatively spliced exon is often regulated in a cell type-specific fashion. AS expression patterns are typically analyzed by RT-PCR and RNA-seq using RNA samples isolated from a population of cells. In situ examination of AS expression patterns for a particular biological structure can be carried out by RNA in situ hybridization (ISH) using exon-specific probes. However, this particular use of ISH has been limited because alternative exons are generally too short to design exon-specific probes. In this report, the use of BaseScope, a recently developed technology that employs short antisense oligonucleotides in RNA ISH, is described to analyze AS expression patterns in mouse brain sections. Exon 23a of neurofibromatosis type 1 (Nf1) is used as an example to illustrate that short exon-exon junction probes exhibit robust hybridization signals with high specificity in RNA ISH analysis on mouse brain sections. More importantly, signals detected with exon inclusion- and skipping-specific probes can be used to reliably calculate the percent spliced in values of Nf1 exon 23a expression in different anatomical areas of a mouse brain. The experimental protocol and calculation method for AS analysis are presented. The results indicate that BaseScope provides a powerful new tool to assess AS expression patterns in situ.

Quantitative Analysis of Alternative Pre-mRNA Splicing in Mouse Brain Sections Using RNA In Situ Hybridization Assay

An in situ hybridization (ISH) protocol that uses short antisense oligonucleotides to detect alternative pre-mRNA splicing patterns in mouse brain sections is described.

Alternative splicing (AS) occurs in more than 90% of human genes. The expression pattern of an alternatively spliced exon is often regulated in a cell ...

Single-Molecule F&ouml;rster Resonance Energy Transfer Methods for Real-Time Investigation of the Holliday Junction Resolution by GEN1

Bulk methods measure the ensemble behavior of molecules, in which individual reaction rates of the underlying steps are averaged throughout the population. Single-molecule F&#246;rster resonance energy transfer (smFRET) provides a recording of the conformational changes taking place by individual molecules in real-time. Therefore, smFRET is powerful in measuring structural changes in the enzyme or substrate during binding and catalysis. This work presents a protocol for single-molecule imaging of the interaction of a four-way Holliday junction (HJ) and gap endonuclease I (GEN1), a cytosolic homologous recombination enzyme. Also presented are single-color and two-color alternating excitation (ALEX) smFRET experimental protocols to follow the resolution of the HJ by GEN1 in real-time. The kinetics of GEN1 dimerization are determined at the HJ, which has been suggested to play a key role in the resolution of the HJ and has remained elusive until now. The techniques described here can be widely applied to obtain valuable mechanistic insights of many enzyme-DNA systems.

Single-Molecule F&amp;#246;rster Resonance Energy Transfer Methods for Real-Time Investigation of the Holliday Junction Resolution by GEN1

Presented here is a protocol for performing single-molecule F&#246;rster resonance energy transfer to study HJ resolution. Two-color alternating excitation is used for determining the dissociation constants. Single-color time lapse smFRET is then applied in real-time cleavage assays to obtain the dwell time distribution prior to HJ resolution.

Bulk methods measure the ensemble behavior of molecules, in which individual reaction rates of the underlying steps are averaged throughout the ...

Investigation of the Transcriptional Role of a RUNX1 Intronic Silencer by CRISPR/Cas9 Ribonucleoprotein in Acute Myeloid Leukemia Cells

The bulk of the human genome (~98%) is comprised of non-coding sequences. Cis-regulatory elements (CREs) are non-coding DNA sequences that contain binding sites for transcriptional regulators to modulate gene expression. Alterations of CREs have been implicated in various diseases including cancer. While promoters and enhancers have been the primary CREs for studying gene regulation, very little is known about the role of silencer, which is another type of CRE that mediates gene repression. Originally identified as an adaptive immunity system in prokaryotes, CRISPR/Cas9 has been exploited to be a powerful tool for eukaryotic genome editing. Here, we present the use of this technique to delete an intronic silencer in the human RUNX1 gene and investigate the impacts on gene expression in OCI-AML3 leukemic cells. Our approach relies on electroporation-mediated delivery of two preassembled Cas9/guide RNA (gRNA) ribonucleoprotein (RNP) complexes to create two double-strand breaks (DSBs) that flank the silencer. Deletions can be readily screened by fragment analysis. Expression analyses of different mRNAs transcribed from alternative promoters help evaluate promoter-dependent effects. This strategy can be used to study other CREs and is particularly suitable for hematopoietic cells, which are often difficult to transfect with plasmid-based methods. The use of a plasmid- and virus-free strategy allows simple and fast assessments of gene regulatory functions.

Investigation of the Transcriptional Role of a RUNX1 Intronic Silencer by CRISPR/Cas9 Ribonucleoprotein in Acute Myeloid Leukemia Cells

Direct delivery of preassembled Cas9/guide RNA ribonucleoprotein complexes is a fast and efficient means for genome editing in hematopoietic cells. Here, we utilize this approach to delete a RUNX1 intronic silencer and examine the transcriptional responses in OCI-AML3 leukemic cells.

The bulk of the human genome (~98%) is comprised of non-coding sequences. Cis-regulatory elements (CREs) are non-coding DNA sequences that contain binding ...

LINE-1 Methylation Analysis in Mesenchymal Stem Cells Treated with Osteosarcoma-Derived Extracellular Vesicles

Methylation-specific probe amplification (MSPA) is a simple and robust technique that can be used to detect relative differences in methylation levels of DNA samples. It is resourceful, requires small amounts of DNA, and takes around 4&#8211;5 h of hands-on work. In the presented technique, DNA samples are first denatured then hybridized to probes that target DNA at either methylated or reference sites as a control. Hybridized DNA is separated into parallel reactions, one undergoing only ligation and the other undergoing ligation followed by HhaI-mediated digestion at unmethylated GCGC sequences. The resultant DNA fragments are amplified by PCR and separated by capillary electrophoresis. Methylated GCGC sites are not digested by HhaI and produce peak signals, while unmethylated GCGC sites are digested and no peak signals are generated. Comparing the control-normalized peaks of digested and undigested versions of each sample provides the methylation dosage ratio of a DNA sample. Here, MSPA is used to detect the effects of osteosarcoma-derived extracellular vesicles (EVs) on the methylation status of long interspersed nuclear element-1 (LINE-1) in mesenchymal stem cells. LINE-1s are repetitive DNA elements that typically undergo hypomethylation in cancer and, in this capacity, may serve as a biomarker. Ultracentrifugation is also used as a cost-effective method to separate extracellular vesicles from biological fluids (i.e., when preparing EV-depleted fetal bovine serum [FBS] and isolating EVs from osteosarcoma conditioned media [differential centrifugation]). For methylation analysis, custom LINE-1 probes are designed to target three methylation sites in the LINE-1 promoter sequence and seven control sites. This protocol demonstrates the use of MSPA for LINE-1 methylation analysis and describes the preparation of EV-depleted FBS by ultracentrifugation.

Described here is the use of a methylation-specific probe amplification method to analyze methylation levels of LINE-1 elements in mesenchymal stem cells treated with osteosarcoma-derived extracellular vesicles. Ultracentrifugation, a popular procedure for separating extracellular vesicles from fetal bovine serum, is also demonstrated.

Methylation-specific probe amplification (MSPA) is a simple and robust technique that can be used to detect relative differences in methylation levels of ...

Genome-wide Analysis of Histone Modifications Distribution using the Chromatin Immunoprecipitation Sequencing Method in Magnaporthe oryzae

Chromatin immunoprecipitation sequencing (ChIP-seq) is a powerful and widely used molecular technique for mapping whole genome locations of transcription factors (TFs), chromatin regulators, and histone modifications, as well as detecting entire genomes for uncovering TF binding patterns and histone posttranslational modifications. Chromatin-modifying activities, such as histone methylation, are often recruited to specific gene regulatory sequences, causing localized changes in chromatin structures and resulting in specific transcriptional effects. The rice blast is a devastating fungal disease on rice throughout the world and is a model system for studying fungus-plant interaction. However, the molecular mechanisms in how the histone modifications regulate their virulence genes in Magnaporthe oryzae remain elusive. More researchers need to use ChIP-seq to study how histone epigenetic modification regulates their target genes. ChIP-seq is also widely used to study the interaction between protein and DNA in animals and plants, but it is less used in the field of plant pathology and has not been well developed. In this paper, we describe the experimental process and operation method of ChIP-seq to identify the genome-wide distribution of histone methylation (such as H3K4me3) that binds to the functional target genes in M. oryzae. Here, we present a protocol to analyze the genome-wide distribution of histone modifications, which can identify new target genes in the pathogenesis of M. oryzae and other filamentous fungi.

Genome-wide Analysis of Histone Modifications Distribution using the Chromatin Immunoprecipitation Sequencing Method in Magnaporthe oryzae

Here, we present a protocol to analyze the genome-wide distribution of histone modifications, which can identify new target genes in the pathogenesis of M. oryzae and other filamentous fungi.

Chromatin immunoprecipitation sequencing (ChIP-seq) is a powerful and widely used molecular technique for mapping whole genome locations of transcription ...

Sample Preparation to Bioinformatics Analysis of DNA Methylation: Association Strategy for Obesity and Related Trait Studies

Obesity is directly connected to lifestyle and has been associated with DNA methylation changes that may cause alterations in the adipogenesis and lipid storage processes contributing to the development of the disease. We demonstrate a complete protocol from selection to epigenetic data analysis of patients with and without obesity. All steps from the protocol were tested and validated in a pilot study. 32 women participated in the study, in which 15 individuals were classified with obesity according to Body Mass Index (BMI) (45.1 &#177; 5.4 kg/m2); and 17 individuals were classified without obesity according to BMI (22.6 &#177; 1.8 kg/m2). In the group with obesity, 564 CpG sites related to fat mass were identified by linear regression analysis. The CpG sites were in the promoter regions. The differential analysis found 470 CpGs hypomethylated and 94 hypermethylated sites in individuals with obesity. The most hypomethylated enriched pathwayswere in the RUNX, WNT signaling, and response to hypoxia. The hypermethylated pathways were related to insulin secretion, glucagon signaling, and Ca2+. We conclude that the protocol effectively identified DNA methylation patterns and trait-related DNA methylation. These patterns could be associated with altered gene expression, affecting adipogenesis and lipid storage. Our results confirmed that an obesogenic lifestyle could promote epigenetic changes in human DNA.

The present study describes the workflow to manage DNA methylation data obtained by microarray technologies. The protocol demonstrates steps from sample preparation to data analysis. All procedures are described in detail, and the video shows the significant steps.

Obesity is directly connected to lifestyle and has been associated with DNA methylation changes that may cause alterations in the adipogenesis and lipid ...