MeDEStrand: an improved method to infer genome-wide absolute methylation level from DNA enrichment experiment

AbstractBackgroundDNA methylation of dinucleotide CpG is an essential epigenetic modification that plays a key role in transcription. Bisulfite conversion method is a “gold standard” for DNA methylation profiling that provides single nucleotide resolution. However, whole-genome bisulfite conversion is very expensive. Alternatively, DNA enrichment-based methods offer high coverage of methylated CpG dinucleotides with the lowest cost per CpG covered genome-wide and have been used widely. They measure the DNA enrichment of methyl-CpG binding, therefore do not directly provide absolute methylation levels. Further, the enrichment is influenced by confounding factors besides the methylation status, e.g., CpG density. Computational models that can accurately derive the absolute methylation levels from the enrichment data are necessary.ResultsWe present ‘MeDEStrand’, a method uses sigmoid function to estimate and correct the CpG bias from the numbers of reads that fell within bins that divide the genome. In addition, unlike the previous methods, which estimate CpG bias based on reads mapped at the same genomic loci, ‘MeDEStrand’ processes the reads for the positive and negative DNA strands separately. We compare the performance of ‘MeDEStrand’ with three other state-of-the-art methods ‘MEDIPS’, ‘BayMeth’ and ‘QSEA’ on four independent datasets generated using immortalized cell lines (GM12878 and K562) and human patient primary cells (foreskin fibroblast and mammary epithelial). Based on the comparison between the inferred absolute methylation levels from MeDIP-seq and the corresponding RRBS data, ‘MeDEStrand’ shows the best performance at high resolution of 25, 50 and 100 base pairs.Conclusions‘MeDEStrand’ benefits from the estimation of CpG bias with a sigmoid function and the procedure to process reads mapped to the positive and negative DNA strands separately. ‘MeDEStrand’ is a tool to infer whole-genome absolute DNA methylation level at the cost of enrichment-based methods with adequate accuracy and resolution. R package ‘MeDEStrand’ and its tutorial is freely available for download at https://github.com/jxu1234/MeDEStrand.git

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Standardization of DNA amount for bisulfite conversion for analyzing the methylation status of LINE-1 in lung cancer

PLoS ONE ◽

10.1371/journal.pone.0256254 ◽

2021 ◽

Vol 16 (8) ◽

pp. e0256254

Author(s):

Duong Anh Thuy Pham ◽

Son Duc Le ◽

Trang Mai Doan ◽

Phuong Thu Luu ◽

Uyen Quynh Nguyen ◽

...

Keyword(s):

Lung Cancer ◽

Dna Methylation ◽

Methylation Level ◽

Genomic Dna ◽

Methylation Status ◽

Cancer Tissue ◽

Nucleotide Position ◽

Bisulfite Conversion ◽

Precise Location ◽

Significant Variance

Highly methylated Long Interspersed Nucleotide Elements 1 (LINE-1) constitute approximately 20% of the human genome, thus serving as a surrogate marker of global genomic DNA methylation. To date, there is still lacking a consensus about the precise location in LINE-1 promoter and its methylation threshold value, making challenging the use of LINE-1 methylation as a diagnostic, prognostic markers in cancer. This study reports on a technical standardization of bisulfite-based DNA methylation analysis, which ensures the complete bisulfite conversion of repeated LINE-1 sequences, thus allowing accurate LINE-1 methylation value. In addition, the study also indicated the precise location in LINE-1 promoter of which significant variance in methylation level makes LINE-1 methylation as a potential diagnostic biomarker for lung cancer. A serial concentration of 5-50-500 ng of DNA from 275 formalin-fixed paraffin-embedded lung tissues were converted by bisulfite; methylation level of two local regions (at nucleotide position 300–368 as LINE-1.1 and 368–460 as LINE-1.2) in LINE-1 promoter was measured by real time PCR. The use of 5 ng of genomic DNA but no more allowed to detect LINE-1 hypomethylation in lung cancer tissue (14.34% versus 16.69% in non-cancerous lung diseases for LINE-1.1, p < 0.0001, and 30.28% versus 32.35% for LINE-1.2, p < 0.05). Our study thus highlighted the optimal and primordial concentration less than 5 ng of genomic DNA guarantees the complete LINE-1 bisulfite conversion, and significant variance in methylation level of the LINE-1 sequence position from 300 to 368 allowed to discriminate lung cancer from non-cancer samples.

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Genome-wide DNA methylation profile changes associated with shell colouration in the Yesso scallop (Patinopecten yessoensis) as measured by whole-genome bisulfite sequencing

BMC Genomics ◽

10.1186/s12864-021-08055-6 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Changzi Yuan ◽

Junxia Mao ◽

Hongyan Sun ◽

Yiying Wang ◽

Ming Guo ◽

...

Keyword(s):

Dna Methylation ◽

Molecular Mechanism ◽

Methylation Level ◽

Current Knowledge ◽

Methylation Status ◽

Vital Role ◽

Patinopecten Yessoensis ◽

Yesso Scallop ◽

Genome Wide ◽

Genome Bisulfite Sequencing

Abstract Background Mollusca, a phylum of highly rich species, possess vivid shell colours, but the underlying molecular mechanism remains to be elucidated. DNA methylation, one of the most common epigenetic modifications in eukaryotes, is believed to play a vital role in various biological processes. However, analysis of the effects of DNA methylation on shell colouration has rarely been performed in molluscs, limiting the current knowledge of the molecular mechanism of shell colour formation. Results In the present study, to reveal the role of epigenetic regulation in shell colouration, WGBS, the “gold standard” of DNA methylation analysis, was first performed on the mantle tissues of Yesso scallops (Patinopecten yessoensis) with different shell colours (brown and white), and DNA methylomes at single-base resolution were generated. About 3% of cytosines were methylated in the genome of the Yesso scallop. A slight increase in mCG percentage and methylation level was found in brown scallops. Sequence preference of nearby methylated cytosines differed between high and low methylation level sites and between the brown- and white-shelled scallops. DNA methylation levels varied among the different genomic regions; all the detected regions in the brown group exhibited higher methylation levels than the white group. A total of 41,175 DMRs (differentially methylated regions) were detected between brown and white scallops. GO functions and pathways associated with the biosynthesis of melanin and porphyrins were significantly enriched for DMRs, among which several key shell colour-related genes were identified. Further, different correlations between mRNA expression levels and DNA methylation status were found in these genes, suggesting that DNA methylation regulates shell colouration in the Yesso scallop. Conclusions This study provides genome-wide DNA methylation landscapes of Yesso scallops with different shell colours, offering new insights into the epigenetic regulatory mechanism underlying shell colour.

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Epigenetic Response of Yarrowia lipolytica to Stress: Tracking Methylation Level and Search for Methylation Patterns via Whole-Genome Sequencing

Microorganisms ◽

10.3390/microorganisms9091798 ◽

2021 ◽

Vol 9 (9) ◽

pp. 1798

Author(s):

Monika Kubiak-Szymendera ◽

Leszek P. Pryszcz ◽

Wojciech Białas ◽

Ewelina Celińska

Keyword(s):

Dna Methylation ◽

Whole Genome Sequencing ◽

Yarrowia Lipolytica ◽

Genome Sequencing ◽

Methylation Level ◽

Epigenetic Modification ◽

Bacterial Species ◽

Whole Genome ◽

Immuno Assay ◽

Methylation Patterns

DNA methylation is a common, but not universal, epigenetic modification that plays an important role in multiple cellular processes. While definitely settled for numerous plant, mammalian, and bacterial species, the genome methylation in different fungal species, including widely studied and industrially-relevant yeast species, Yarrowia lipolytica, is still a matter of debate. In this paper, we report a differential DNA methylation level in the genome of Y. lipolytica subjected to sequential subculturing and to heat stress conditions. To this end, we adopted repeated batch bioreactor cultivations of Y. lipolytica subjected to thermal stress in specific time intervals. To analyze the variation in DNA methylation between stressed and control cultures, we (a) quantified the global DNA methylation status using an immuno-assay, and (b) studied DNA methylation patterns through whole-genome sequencing. Primarily, we demonstrated that 5 mC modification can be detected using a commercial immuno-assay, and that the modifications are present in Y. lipolytica’s genome at ~0.5% 5 mC frequency. On the other hand, we did not observe any changes in the epigenetic response of Y. lipolytica to heat shock (HS) treatment. Interestingly, we identified a general phenomenon of decreased 5 mC level in Y. lipolytica’s genome in the stationary phase of growth, when compared to a late-exponential epigenome. While this study provides an insight into the subculturing stress response and adaptation to the stress at epigenetic level by Y. lipolytica, it also leaves an open question of inability to detect any genomic DNA methylation level (either in CpG context or context-less) through whole-genome sequencing. The results of ONT sequencing, suggesting that 5 mC modification is either rare or non-existent in Y. lipolytica genome, are contradicted with the results of the immunoassay.

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Whole-Genome DNA Methylation Analysis in Hydrogen Peroxide Overproducing Transgenic Tobacco Resistant to Biotic and Abiotic Stresses

Plants ◽

10.3390/plants10010178 ◽

2021 ◽

Vol 10 (1) ◽

pp. 178

Author(s):

Ana L. Villagómez-Aranda ◽

Luis F. García-Ortega ◽

Irineo Torres-Pacheco ◽

Ramón G. Guevara-González

Keyword(s):

Hydrogen Peroxide ◽

Dna Methylation ◽

Transgenic Tobacco ◽

Stress Responses ◽

Abiotic Stresses ◽

Methylation Status ◽

Physiological Adaptation ◽

Whole Genome ◽

Sequencing Analysis ◽

Biotic And Abiotic Stresses

Epigenetic regulation is a key component of stress responses, acclimatization and adaptation processes in plants. DNA methylation is a stable mark plausible for the inheritance of epigenetic traits, such that it is a potential scheme for plant breeding. However, the effect of modulators of stress responses, as hydrogen peroxide (H2O2), in the methylome status has not been elucidated. A transgenic tobacco model to the CchGLP gene displayed high H2O2 endogen levels correlated with biotic and abiotic stresses resistance. The present study aimed to determine the DNA methylation status changes in the transgenic model to obtain more information about the molecular mechanism involved in resistance phenotypes. The Whole-genome bisulfite sequencing analysis revealed a minimal impact of overall levels and distribution of methylation. A total of 9432 differential methylated sites were identified in distinct genome regions, most of them in CHG context, with a trend to hypomethylation. Of these, 1117 sites corresponded to genes, from which 83 were also differentially expressed in the plants. Several genes were associated with respiration, energy, and calcium signaling. The data obtained highlighted the relevance of the H2O2 in the homeostasis of the system in stress conditions, affecting at methylation level and suggesting an association of the H2O2 in the physiological adaptation to stress functional linkages may be regulated in part by DNA methylation.

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Genome-Wide DNA Methylation Pattern of Cancer Stem Cells in Esophageal Cancer

Technology in Cancer Research & Treatment ◽

10.1177/1533033820983793 ◽

2020 ◽

Vol 19 ◽

pp. 153303382098379

Author(s):

Xiying Yu ◽

Ying Teng ◽

Xingran Jiang ◽

Hui Yuan ◽

Wei Jiang

Keyword(s):

Dna Methylation ◽

Stem Cells ◽

Esophageal Cancer ◽

Cancer Stem Cells ◽

Side Population ◽

Methylation Status ◽

Methylation Profile ◽

Cpg Dinucleotides ◽

Genome Wide ◽

Differentially Methylated Genes

Background: Cancer stem cells (CSCs) are considered the main cause of cancer recurrence and metastasis, and DNA methylation is involved in the maintenance of CSCs. However, the methylation profile of esophageal CSCs remains unknown. Methods: Side population (SP) cells were isolated from esophageal squamous cell carcinoma (ESCC) cell lines KYSE150 and EC109. Sphere-forming cells were collected from human primary esophageal cancer cells. SP cells and sphere-forming cells were used as substitutes for cancer stem-like cells. We investigated the genome-wide DNA methylation profile in esophageal cancer stem-like cells using reduced representation bisulfite sequencing (RRBS). Results: Methylated cytosine (mC) was found mostly in CpG dinucleotides, located mostly in the intronic, intergenic, and exonic regions. Forty intersected differentially methylated regions (DMRs) were identified in these 3 groups of samples. Thirteen differentially methylated genes with the same alteration trend were detected; these included OTX1, SPACA1, CD163L1, ST8SIA2, TECR, CADM3, GRM1, LRRK1, CHSY1, PROKR2, LINC00658, LOC100506688, and NKD2. DMRs covering ST8SIA2 and GRM1 were located in exons. These differentially methylated genes were involved in 10 categories of biological processes and 3 cell signaling pathways. Conclusions: When compared to non-CSCs, cancer stem-like cells have a differential methylation status, which provides an important biological base for understanding esophageal CSCs and developing therapeutic targets for esophageal cancer.

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Abstract 40: Disturbed Flow Alters Genomewide DNA Methylation Patterns, Regulating Endothelial Gene Expression and Atherosclerosis

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.34.suppl_1.40 ◽

2014 ◽

Vol 34 (suppl_1) ◽

Author(s):

Jessilyn Dunn ◽

Haiwei Qiu ◽

Soyeon Kim ◽

Daudi Jjingo ◽

Ryan Hoffman ◽

...

Keyword(s):

Gene Expression ◽

Dna Methylation ◽

Dna Methyltransferase ◽

Methylation Status ◽

Western Diet ◽

Dependent Manner ◽

Gene Promoters ◽

Genome Wide ◽

Methylation Patterns ◽

Endothelial Gene Expression

Atherosclerosis preferentially occurs in arterial regions of disturbed blood flow (d-flow), which alters gene expression, endothelial function, and atherosclerosis. Here, we show that d-flow regulates genome-wide DNA methylation patterns in a DNA methyltransferase (DNMT)-dependent manner. We found that d-flow induced expression of DNMT1, but not DNMT3a or DNMT3b, in mouse arterial endothelium in vivo and in cultured endothelial cells by oscillatory shear (OS) compared to unidirectional laminar shear in vitro. The DNMT inhibitor 5-Aza-2’deoxycytidine (5Aza) or DNMT1 siRNA significantly reduced OS-induced endothelial inflammation. Moreover, 5Aza reduced lesion formation in two atherosclerosis models using ApoE-/- mice (western diet for 3 months and the partial carotid ligation model with western diet for 3 weeks). To identify the 5Aza mechanisms, we conducted two genome-wide studies: reduced representation bisulfite sequencing (RRBS) and transcript microarray using endothelial-enriched gDNA and RNA, respectively, obtained from the partially-ligated left common carotid artery (LCA exposed to d-flow) and the right contralateral control (RCA exposed to s-flow) of mice treated with 5Aza or vehicle. D-flow induced DNA hypermethylation in 421 gene promoters, which was significantly prevented by 5Aza in 335 genes. Systems biological analyses using the RRBS and the transcriptome data revealed 11 mechanosensitive genes whose promoters were hypermethylated by d-flow but rescued by 5Aza treatment. Of those, five genes contain hypermethylated cAMP-response-elements in their promoters, including the transcription factors HoxA5 and Klf3. Their methylation status could serve as a mechanosensitive master switch in endothelial gene expression. Our results demonstrate that d-flow controls epigenomic DNA methylation patterns in a DNMT-dependent manner, which in turn alters endothelial gene expression and induces atherosclerosis.

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Low-pass whole genome bisulfite sequencing of neonatal dried blood spots identifies a role for RUNX1 in Down syndrome DNA methylation profiles

Human Molecular Genetics ◽

10.1093/hmg/ddaa218 ◽

2020 ◽

Author(s):

Benjamin I Laufer ◽

Hyeyeon Hwang ◽

Julia M Jianu ◽

Charles E Mordaunt ◽

Ian F Korf ◽

...

Keyword(s):

Dna Methylation ◽

Down Syndrome ◽

Early Life ◽

Trisomy 21 ◽

Bisulfite Sequencing ◽

Dried Blood Spots ◽

Whole Genome ◽

Genome Wide ◽

Low Pass ◽

Genome Bisulfite Sequencing

Abstract Neonatal dried blood spots (NDBS) are a widely banked sample source that enables retrospective investigation into early life molecular events. Here, we performed low-pass whole genome bisulfite sequencing (WGBS) of 86 NDBS DNA to examine early life Down syndrome (DS) DNA methylation profiles. DS represents an example of genetics shaping epigenetics, as multiple array-based studies have demonstrated that trisomy 21 is characterized by genome-wide alterations to DNA methylation. By assaying over 24 million CpG sites, thousands of genome-wide significant (q < 0.05) differentially methylated regions (DMRs) that distinguished DS from typical development and idiopathic developmental delay were identified. Machine learning feature selection refined these DMRs to 22 loci. The DS DMRs mapped to genes involved in neurodevelopment, metabolism, and transcriptional regulation. Based on comparisons with previous DS methylation studies and reference epigenomes, the hypermethylated DS DMRs were significantly (q < 0.05) enriched across tissues while the hypomethylated DS DMRs were significantly (q < 0.05) enriched for blood-specific chromatin states. A ~28 kb block of hypermethylation was observed on chromosome 21 in the RUNX1 locus, which encodes a hematopoietic transcription factor whose binding motif was the most significantly enriched (q < 0.05) overall and specifically within the hypomethylated DMRs. Finally, we also identified DMRs that distinguished DS NDBS based on the presence or absence of congenital heart disease (CHD). Together, these results not only demonstrate the utility of low-pass WGBS on NDBS samples for epigenome-wide association studies, but also provide new insights into the early life mechanisms of epigenomic dysregulation resulting from trisomy 21.

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A Bayesian approach for analysis of whole-genome bisulphite sequencing data identifies disease-associated changes in DNA methylation

10.1101/041715 ◽

2016 ◽

Author(s):

Owen J.L. Rackham ◽

Sarah R. Langley ◽

Thomas Oates ◽

Eleni Vradi ◽

Nathan Harmston ◽

...

Keyword(s):

Dna Methylation ◽

Epigenetic Modification ◽

Promoter Hypermethylation ◽

Whole Genome ◽

Sequencing Data ◽

Accurate Identification ◽

Bisulphite Sequencing ◽

Consistent Change ◽

Rat Strain ◽

Differential Transcription

ABSTRACTDNA methylation is a key epigenetic modification involved in gene regulation whose contribution to disease susceptibility remains to be fully understood. Here, we present a novel Bayesian smoothing approach (called ABBA) to detect differentially methylated regions (DMRs) from whole-genome bisulphite sequencing (WGBS). We also show how this approach can be leveraged to identify disease-associated changes in DNA methylation, suggesting mechanisms through which these alterations might affect disease. From a data modeling perspective, ABBA has the distinctive feature of automatically adapting to different correlation structures in CpG methylation levels across the genome whilst taking into account the distance between CpG sites as a covariate. Our simulation study shows that ABBA has greater power to detect DMRs than existing methods, providing an accurate identification of DMRs in the large majority of simulated cases. To empirically demonstrate the method’s efficacy in generating biological hypotheses, we performed WGBS of primary macrophages derived from an experimental rat system of glomerulonephritis and used ABBA to identify >1,000 disease-associated DMRs. Investigation of these DMRs revealed differential DNA methylation localized to a 600bp region in the promoter of the Ifitm3 gene. This was confirmed by ChIP-seq and RNA-seq analyses, showing differential transcription factor binding at the Ifitm3 promoter by JunD (an established determinant of glomerulonephritis) and a consistent change in Ifitm3 expression. Our ABBA analysis allowed us to propose a new role for Ifitm3 in the pathogenesis of glomerulonephritis via a mechanism involving promoter hypermethylation that is associated with Ifitm3 repression in the rat strain susceptible to glomerulonephritis.

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BIOM-23. A PILOT STUDY OF WHOLE GENOME SEQUENCING (WGS) OF PLASMA CELL-FREE DNA (cfDNA) FOR ULTRASENSITIVE DETECTION OF TUMOR DNA IN PATIENTS WITH GLIOBLASTOMA (GBM)

Neuro-Oncology ◽

10.1093/neuonc/noab196.054 ◽

2021 ◽

Vol 23 (Supplement_6) ◽

pp. vi15-vi15

Author(s):

Stephen J Bagley ◽

Jacob Till ◽

Aseel Abdalla ◽

MacLean Nasrallah ◽

Tomer Lauterman ◽

...

Keyword(s):

Pilot Study ◽

Whole Genome Sequencing ◽

Genome Sequencing ◽

Tumor Tissue ◽

Methylation Status ◽

Tumor Burden ◽

Whole Genome ◽

Newly Diagnosed ◽

Genome Wide ◽

Tumor Dna

Abstract BACKGROUND Plasma circulating tumor DNA (ctDNA) is rarely detectable by traditional methods in patients with GBM. As a result, unlike in lung and other cancers, serial next generation sequencing of ctDNA for monitoring GBM tumor burden has been challenging. In light of the low tumor fraction (TF) of DNA fragments in GBM patient plasma and the urgent need to improve upon MRI for tracking GBM tumor burden, we conducted a pilot study in patients with newly diagnosed GBM using the C2 intelligence platform (C2i Genomics), which leverages genome-wide mutational integration for highly sensitive ctDNA detection. METHODS Plasma was collected pre- and post-operatively in patients with newly diagnosed GBM undergoing surgical resection/biopsy. cfDNA was extracted, quantified, and analyzed for fragment size. Genomic DNA (gDNA) was extracted from matched tumor tissue. Whole genome sequencing (WGS) was performed on both gDNA and cfDNA. A specific copy number alteration (CNA) compendium was created for each patient to generate a readout of TF (Zviran, Nat Medicine 2020). We assessed the association between TF at post-operative day 1 (a surrogate for residual disease) and OS, adjusting for other prognostic factors using Cox regression. RESULTS 37 patients were enrolled. For samples with high tumor fraction (n=5), a statistically significant (p< 1e-4) correlation between CNA profiles of tumor tissue and plasma samples was observed. Post-operative TF above the median value was associated with inferior OS (median 7.7 vs. 19.3 months, p=0.019). This association persisted after adjusting for age, O6-methylguanine-DNA methyltransferase methylation status, extent of resection, and performance status (adjusted HR 2.5, 95% CI 1.1-5.6, p=0.03). CONCLUSION Genome-wide mutational integration enables ultra-sensitive detection of ctDNA in GBM patient plasma. Post-operative TF measured by the C2i test is independently associated with OS in newly diagnosed GBM, providing the foundation to evaluate this technology for personalized prognostication and disease monitoring.

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Genome-Wide DNA Methylation Profiling in the Lotus (Nelumbo nucifera) Flower Showing its Contribution to the Stamen Petaloid

Plants ◽

10.3390/plants8050135 ◽

2019 ◽

Vol 8 (5) ◽

pp. 135 ◽

Cited By ~ 5

Author(s):

Zhongyuan Lin ◽

Meihui Liu ◽

Rebecca Njeri Damaris ◽

Tonny Maraga Nyong’a ◽

Dingding Cao ◽

...

Keyword(s):

Gene Expression ◽

Dna Methylation ◽

Bisulfite Sequencing ◽

Epigenetic Modification ◽

Nelumbo Nucifera ◽

Flower Formation ◽

Relationship Analysis ◽

Genome Wide ◽

Dna Methylation Profiling ◽

Methylation Profiling

DNA methylation is a vital epigenetic modification. Methylation has a significant effect on the gene expression influencing the regulation of different physiological processes. Current studies on DNA methylation have been conducted on model plants. Lotus (Nelumbo nucifera) is a basic eudicot exhibiting variations during development, especially in flower formation. DNA methylation profiling was conducted on different flower tissues of lotuses through whole genome bisulfite sequencing (WGBS) to investigate the effects of DNA methylation on its stamen petaloid. A map of methylated cytosines at the single base pair resolution for the lotus was constructed. When the stamen was compared with the stamen petaloid, the DNA methylation exhibited a global decrease. Genome-wide relationship analysis between DNA methylation and gene expression identified 31 different methylation region (DMR)-associated genes, which might play crucial roles in floral organ formation, especially in the stamen petaloid. One out of 31 DMR-associated genes, NNU_05638 was homolog with Plant U-box 33 (PUB33). The DNA methylation status of NNU_05638 promoter was distinct in three floral organs, which was confirmed by traditional bisulfite sequencing. These results provide further insights about the regulation of stamen petaloids at the epigenetic level in lotus.

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