Whole genome bisulphite sequencing using the Illumina X system [Infinium MethylationEPIC]
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ABSTRACT: While Illumina X technology has helped to reduce the cost of whole genome sequencing substantially, its application for bisulphite sequencing is not straightforward. We describe the optimization of a library preparation and sequencing approach that maximizes the yield and quality of sequencing, and how to eliminate a previously unrecognized artefact affecting several percent of bisulphite sequencing reads.
Project description:While Illumina X technology has helped to reduce the cost of whole genome sequencing substantially, its application for bisulphite sequencing is not straightforward. We describe the optimization of a library preparation and sequencing approach that maximizes the yield and quality of sequencing, and how to eliminate a previously unrecognized artefact affecting several percent of bisulphite sequencing reads.
Project description:While Illumina X technology has helped to reduce the cost of whole genome sequencing substantially, its application for bisulphite sequencing is not straightforward. We describe the optimization of a library preparation and sequencing approach that maximizes the yield and quality of sequencing, and how to eliminate a previously unrecognized artefact affecting several percent of bisulphite sequencing reads.
Project description:While Illumina X technology has helped to reduce the cost of whole genome sequencing substantially, its application for bisulphite sequencing is not straightforward. We describe the optimization of a library preparation and sequencing approach that maximizes the yield and quality of sequencing, and how to eliminate a previously unrecognized artefact affecting several percent of bisulphite sequencing reads.
Project description:Bisulphite (BS) converted DNA from 2 paternal uniparental diploidies (pUPDs), one maternal (mUPD) and 5 control leukocytes samples were hybridized to the Infinium HumanMethylationEPIC BeadChip (Illumina), obtaining the BS DNA methylation profiles across approximately 850,000 CpGs. In addition, the 5 control leukocyte samples were also coverted using oxidative bisulphite (oxBS) treatment. The selective chemical oxidation of 5-hydroxymethylcytosine (5hmC) to 5-formylcytosine (5fC) and the deamination of the latter to uracil during the BS conversion allowed the quantification of independent 5-methylcytosine (5mC) and 5hmC methylation levels at every single CpG.
Project description:Infinium Methylation BeadChips are widely used to profile DNA cytosine modifications in large cohort studies for reasons of cost-effectiveness, accurate quantification, and user-friendly data analysis in characterizing these canonical epigenetic marks. In this work, we conducted a comprehensive evaluation of the updated Infinium MethylationEPIC v2 BeadChip (EPICv2). Our evaluation revealed that EPICv2 offers significant improvements over its predecessors, including expanded enhancer coverage, applicability to diverse ancestry groups, support for low-input DNA down to one nanogram, coverage of existing epigenetic clocks, cell type deconvolution panels, and human trait associations, while maintaining accuracy and reproducibility. Using EPICv2, we were able to identify epigenome and sequence signatures in cell line models of DNMT and SETD2 loss and/or hypomorphism. Furthermore, we provided probe-wise evaluation and annotation to facilitate the use of new features on this array for studying the interplay between somatic mutations and epigenetic landscape in cancer genomics. In conclusion, EPICv2 provides researchers with a valuable tool for studying epigenetic modifications and their role in development and disease.
Project description:DNA methylation of CpG sites is commonly measured using Illumina Infinium BeadChip platforms. The Infinium MethylationEPIC array has replaced the Infinium Methylation450K array. The two arrays use the same technology, with the EPIC array assaying almost double the number of sites than the 450K array. In this study, we compare DNA methylation values of shared CpGs of the same human cartilage samples assayed using both platforms. DNA methylation was measured in 21 human cartilage samples using the both 450K and EPIC arrays. Additional matched 450K and EPIC data in whole tumour and whole blood were downloaded from GEO GSE92580 and GSE86833, respectively. Data were processed using the Bioconductor package Minfi. DNA methylation of six CpG sites was validated for the same 21 cartilage samples by pyrosequencing. In cartilage samples, overall sample correlations of methylation values between arrays were high (Pearson's r > 0.96). However, 50.5% of CpG sites showed poor correlation (r < 0.2) between arrays. Sites with limited variance and with either very high or very low methylation levels in cartilage exhibited lower correlation values, corroborating prior studies in whole blood. Bisulphite pyrosequencing did not highlight one array as generating more accurate methylation values. For a specific CpG site, the array methylation correlation coefficient differed between cartilage, tumour, and whole blood, reflecting the difference in methylation variance between cell types. Researchers should be cautious when analysing methylation of CpG sites that show low methylation variance within the cell type of interest, regardless of the method used to assay methylation.
Project description:Bisulphite sequencing enables DNA methylation analysis of every cytosine residue. We have optimized conditions for combining chromatin immunoprecipation (ChIP) with high throughput bisulphite sequencing to study the relationship between histone modifications and DNA methylation.
Project description:Library preparation for whole genome bisulphite sequencing (WGBS) is challenging due to side effects of the bisulphite treatment, which leads to extensive DNA damage. Recently, a new generation of methods for bisulphite sequencing library preparation have been devised. They are based on initial bisulphite treatment of the DNA, followed by adaptor tagging of single stranded DNA fragments, and enable WGBS using low quantities of input DNA. In this study, we present a novel approach for quick and cost effective WGBS library preparation that is based on splinted adaptor tagging (SPLAT) of bisulphite-converted single-stranded DNA. Moreover, we validate SPLAT against three commercially available WGBS library preparation techniques, two of which are based on bisulphite treatment prior to adaptor tagging and one is a conventional WGBS method.
Project description:The Infinium MethylationEPIC BeadChip (EPIC) is a reliable method for measuring the DNA methylation of more than 850,000 CpG positions. In clinical and forensic settings, it is critical to be able to work with low DNA amounts without risking reduced reproducibility. We evaluated the EPIC for a range of DNA amounts using two-fold serial dilutions investigated on two different days. While the β-value distributions were generally unaffected by decreasing DNA amounts, the median squared Pearson's correlation coefficient (R2) of between-days β-value comparisons decreased from 0.994 (500 ng DNA) to 0.957 (16 ng DNA). The median standard deviation of the β-values was 0.005 and up to 0.017 (median of medians: 0.014) for β-values around 0.6-0.7. With decreasing amounts of DNA from 500 ng to 16 ng, the percentage of probes with standard deviations ≤ 0.1 decreased from 99.9% to 99.4%. This study showed that high reproducibility results are obtained with DNA amounts in the range 125-500 ng DNA, while DNA amounts equal to 63 ng or below gave less reproducible results.
Project description:BackgroundThe advent of array-based genome-wide DNA methylation methods has enabled quantitative measurement of single CpG methylation status at relatively low cost and sample input. Whereas the use of Infinium Human Methylation BeadChips has shown great utility in clinical studies, no equivalent tool is available for rodent animal samples. We examined the feasibility of using the new Infinium MethylationEPIC BeadChip for studying DNA methylation in mouse.ResultsIn silico, we identified 19,420 EPIC probes (referred as mEPIC probes), which align with a unique best alignment score to the bisulfite converted reference mouse genome mm10. Further annotation revealed that 85% of mEPIC probes overlapped with mm10.refSeq genes at different genomic features including promoters (TSS1500 and TSS200), 1st exons, 5'UTRs, 3'UTRs, CpG islands, shores, shelves, open seas and FANTOM5 enhancers. Hybridization of mouse samples to Infinium Human MethylationEPIC BeadChips showed successful measurement of mEPIC probes and reproducibility between inter-array biological replicates. Finally, we demonstrated the utility of mEPIC probes for data exploration such as hierarchical clustering.ConclusionsGiven the absence of cost and labor convenient genome-wide technologies in the murine system, our findings show that the Infinium MethylationEPIC BeadChip platform is suitable for investigation of the mouse methylome. Furthermore, we provide the "mEPICmanifest" with genomic features, available to users of Infinium Human MethylationEPIC arrays for mouse samples.