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...

<ol>
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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

9.8K Views.  Gothenburg University. 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 unbia...