methylC Track: visual integration of single-base resolution DNA methylation data on the WashU EpiGenome Browser

Targeting the chromatin structural changes of antitumor immunity

Epigenomic imbalance drives abnormal transcriptional processes, promoting the onset and progression of cancer. Although defective gene regulation generally affects carcinogenesis and tumor suppression networks, tumor immunogenicity and immune cells involved in antitumor responses may also be affected by epigenomic changes, which may have significant implications for the development and application of epigenetic therapy, cancer immunotherapy, and their combinations. Herein, we focus on the impact of epigenetic regulation on tumor immune cell function and the role of key abnormal epigenetic processes, DNA methylation, histone post-translational modification, and chromatin structure in tumor immunogenicity, and introduce these epigenetic research methods. We emphasize the value of small-molecule inhibitors of epigenetic modulators in enhancing antitumor immune responses and discuss the challenges of developing treatment plans that combine epigenetic therapy and immunotherapy through the complex interaction between cancer epigenetics and cancer immunology.

Modbed track: Visualization of modified bases in single-molecule sequencing

Recent advances in long-read sequencing technologies have not only dramatically increased sequencing read length but also have improved the accuracy of detecting chemical modifications to the canonical nucleotide bases, thus opening exciting venues to investigate the epigenome. Currently, the ability to visualize modified bases from long-read sequencing data in genome browsers is still limited, preventing users from easily and fully exploring these type of data. To address this limitation, the WashU Epigenome Browser introduces the modbed track type, which provides visualization of modification details in each single read as well as aggregated modifications of individual or multiple molecules across a dynamic range of resolutions. The modbed file can be uploaded for visualization as a local track or viewed with an accessible URL freely on the WashU Epigenome Browser at https://epigenomegateway.wustl.edu/.

Disruption of CDK7 signaling leads to catastrophic chromosomal instability coupled with a loss of condensin-mediated chromatin compaction

Chromatin organization is highly dynamic and modulates DNA replication, transcription, and chromosome segregation. Condensin is essential for chromosome assembly during mitosis and meiosis, as well as maintenance of chromosome structure during interphase. While it is well established that sustained condensin expression is necessary to ensure chromosome stability, the mechanisms that control its expression are not yet known. Herein, we report that disruption of cyclin-dependent kinase 7 (CDK7), the core catalytic subunit of CDK-activating kinase, leads to reduced transcription of several condensin subunits, including structural maintenance of chromosomes 2 (SMC2). Live and static microscopy revealed that inhibiting CDK7 signaling prolongs mitosis and induces chromatin bridge formation, DNA double-strand breaks, and abnormal nuclear features, all of which are indicative of mitotic catastrophe and chromosome instability. Affirming the importance of condensin regulation by CDK7, genetic suppression of the expression of SMC2, a core subunit of this complex, phenocopies CDK7 inhibition. Moreover, analysis of genome-wide chromatin conformation using Hi-C revealed that sustained activity of CDK7 is necessary to maintain chromatin sublooping, a function that is ascribed to condensin. Notably, the regulation of condensin subunit gene expression is independent of superenhancers. Together, these studies reveal a new role for CDK7 in sustaining chromatin configuration by ensuring the expression of condensin genes, including SMC2.

Aberrant Methylation of the Imprinted C19MC and MIR371-3 Clusters in Patients with Non-Small Cell Lung Cancer

Epigenetic mechanisms have emerged as an important contributor to tumor development through the modulation of gene expression. Our objective was to identify the methylation profile of the imprinted C19MC and MIR371-3 clusters in patients with non-small cell lung cancer (NSCLC) and to find their potential target genes, as well as to study their prognostic role. DNA methylation status was analyzed in a NSCLC patient cohort (n = 47) and compared with a control cohort including COPD patients and non-COPD subjects (n = 23) using the Illumina Infinium Human Methylation 450 BeadChip. Hypomethylation of miRNAs located on chromosome 19q13.42 was found to be specific for tumor tissue. We then identified the target mRNA-miRNA regulatory network for the components of the C19MC and MIR371-3 clusters using the miRTargetLink 2.0 Human tool. The correlations of miRNA-target mRNA expression from primary lung tumors were analyzed using the CancerMIRNome tool. From those negative correlations identified, we found that a lower expression of 5 of the target genes (FOXF2, KLF13, MICA, TCEAL1 and TGFBR2) was significantly associated with poor overall survival. Taken together, this study demonstrates that the imprinted C19MC and MIR371-3 miRNA clusters undergo polycistronic epigenetic regulation leading to deregulation of important and common target genes with potential prognostic value in lung cancer.

WashU Epigenome Browser update 2022

WashU Epigenome Browser (https://epigenomegateway.wustl.edu/browser/) is a web-based genomic data exploration tool that provides visualization, integration, and analysis of epigenomic datasets. The newly renovated user interface and functions have enabled researchers to engage with the browser and genomic data more efficiently and effectively since 2018. Here, we introduce a new integrated panel design in the browser that allows users to interact with 1D (genomic features), 2D (such as Hi-C), 3D (genome structure), and 4D (time series) data in a single web page. The browser can display three-dimensional chromatin structures with the 3D viewer module. The 4D tracks, called ‘Dynamic’ tracks, animatedly display time-series data, allowing for a more striking visual impact to identify the gene or genomic region candidates as a function of time. Genomic data, such as annotation features, numerical values, and chromatin interaction data can all be viewed in the dynamic track mode. Imaging data from microscopy experiments can also be displayed in the browser. In addition to software development, we continue to service and expand the data hubs we host for large consortia including 4DN, Roadmap Epigenomics, TaRGET and ENCODE, among others. Our growing user/developer community developed additional track types as plugins, such as qBed and dynseq tracks, which extend the utility of the browser. The browser serves as a foundation for additional genomics platforms including the WashU Virus Genome Browser (for COVID-19 research) and the Comparative Genome Browser. The WashU Epigenome Browser can also be accessed freely through Amazon Web Services at https://epigenomegateway.org/.

A map of cis-regulatory elements and 3D genome structures in zebrafish

The zebrafish (Danio rerio) has been widely used in the study of human disease and development, and about 70% of the protein-coding genes are conserved between the two species¹. However, studies in zebrafish remain constrained by the sparse annotation of functional control elements in the zebrafish genome. Here we performed RNA sequencing, assay for transposase-accessible chromatin using sequencing (ATAC-seq), chromatin immunoprecipitation with sequencing, whole-genome bisulfite sequencing, and chromosome conformation capture (Hi-C) experiments in up to eleven adult and two embryonic tissues to generate a comprehensive map of transcriptomes, cis-regulatory elements, heterochromatin, methylomes and 3D genome organization in the zebrafish Tübingen reference strain. A comparison of zebrafish, human and mouse regulatory elements enabled the identification of both evolutionarily conserved and species-specific regulatory sequences and networks. We observed enrichment of evolutionary breakpoints at topologically associating domain boundaries, which were correlated with strong histone H3 lysine 4 trimethylation (H3K4me3) and CCCTC-binding factor (CTCF) signals. We performed single-cell ATAC-seq in zebrafish brain, which delineated 25 different clusters of cell types. By combining long-read DNA sequencing and Hi-C, we assembled the sex-determining chromosome 4 de novo. Overall, our work provides an additional epigenomic anchor for the functional annotation of vertebrate genomes and the study of evolutionarily conserved elements of 3D genome organization.

STARR-seq identifies active, chromatin-masked, and dormant enhancers in pluripotent mouse embryonic stem cells

BACKGROUND

Enhancers are distal regulators of gene expression that shape cell identity and control cell fate transitions. In mouse embryonic stem cells (mESCs), the pluripotency network is maintained by the function of a complex network of enhancers, that are drastically altered upon differentiation. Genome-wide chromatin accessibility and histone modification assays are commonly used as a proxy for identifying putative enhancers and for describing their activity levels and dynamics.

RESULTS

Here, we applied STARR-seq, a genome-wide plasmid-based assay, as a read-out for the enhancer landscape in "ground-state" (2i+LIF; 2iL) and "metastable" (serum+LIF; SL) mESCs. This analysis reveals that active STARR-seq loci show modest overlap with enhancer locations derived from peak calling of ChIP-seq libraries for common enhancer marks. We unveil ZIC3-bound loci with significant STARR-seq activity in SL-ESCs. Knock-out of Zic3 removes STARR-seq activity only in SL-ESCs and increases their propensity to differentiate towards the endodermal fate. STARR-seq also reveals enhancers that are not accessible, masked by a repressive chromatin signature. We describe a class of dormant, p53 bound enhancers that gain H3K27ac under specific conditions, such as after treatment with Nocodazol, or transiently during reprogramming from fibroblasts to pluripotency.

CONCLUSIONS

In conclusion, loci identified as active by STARR-seq often overlap with those identified by chromatin accessibility and active epigenetic marking, yet a significant fraction is epigenetically repressed or display condition-specific enhancer activity.

The Roles of Imprinted SLC22A18 and SLC22A18AS Gene Overexpression Caused by Promoter CpG Island Hypomethylation as Diagnostic and Prognostic Biomarkers for Non-Small Cell Lung Cancer Patients

Genomic imprinting is a process that involves one gene copy turned-off in a parent-of-origin-dependent manner. The regulation of imprinted genes is broadly dependent on promoter methylation marks, which are frequently associated with both oncogenes and tumor suppressors. The purpose of this study was to assess the DNA methylation patterns of the imprinted solute-carrier family 22 member 18 (SLC22A18) and SLC22A18 antisense (SLC22A18AS) genes in non-small cell lung cancer (NSCLC) patients to study their relevance to the disease. We found that both genes were hypomethylated in adenocarcinoma and squamous cell carcinoma patients. Due to this imprinting loss, SLC22A18 and SLC22A18AS were found to be overexpressed in NSCLC tissues, which is significantly more evident in lung adenocarcinoma patients. These results were validated through analyses of public databases of NSCLC patients. The reversed gene profile of both genes was achieved in vitro by treatment with ademetionine. We then showed that high SLC22A18 and SLC22A18AS expression levels were significantly associated with worsening disease progression. In addition, low levels of SLC22A18AS were also correlated with better overall survival for lung adenocarcinoma patients. We found that SLC22A18 and SLC22A18AS knockdown inhibits cell proliferation in vitro. All these results suggest that both genes may be useful as diagnostic and prognostic biomarkers in NSCLC, revealing novel therapeutic opportunities.

Regenerating zebrafish fin epigenome is characterized by stable lineage-specific DNA methylation and dynamic chromatin accessibility

BACKGROUND

Zebrafish can faithfully regenerate injured fins through the formation of a blastema, a mass of proliferative cells that can grow and develop into the lost body part. After amputation, various cell types contribute to blastema formation, where each cell type retains fate restriction and exclusively contributes to regeneration of its own lineage. Epigenetic changes that are associated with lineage restriction during regeneration remain underexplored.

RESULTS

We produce epigenome maps, including DNA methylation and chromatin accessibility, as well as transcriptomes, of osteoblasts and other cells in uninjured and regenerating fins. This effort reveals regeneration as a process of highly dynamic and orchestrated transcriptomic and chromatin accessibility changes, coupled with stably maintained lineage-specific DNA methylation. The epigenetic signatures also reveal many novel regeneration-specific enhancers, which are experimentally validated. Regulatory networks important for regeneration are constructed through integrative analysis of the epigenome map, and a knockout of a predicted upstream regulator disrupts normal regeneration, validating our prediction.

CONCLUSION

Our study shows that lineage-specific DNA methylation signatures are stably maintained during regeneration, and regeneration enhancers are preset as hypomethylated before injury. In contrast, chromatin accessibility is dynamically changed during regeneration. Many enhancers driving regeneration gene expression as well as upstream regulators of regeneration are identified and validated through integrative epigenome analysis.

The UCSC Genome Browser database: 2018 update

The UCSC Genome Browser (https://genome.ucsc.edu) provides a web interface for exploring annotated genome assemblies. The assemblies and annotation tracks are updated on an ongoing basis—12 assemblies and more than 28 tracks were added in the past year. Two recent additions are a display of CRISPR/Cas9 guide sequences and an interactive navigator for gene interactions. Other upgrades from the past year include a command-line version of the Variant Annotation Integrator, support for Human Genome Variation Society variant nomenclature input and output, and a revised highlighting tool that now supports multiple simultaneous regions and colors.

The interaction between oxytocin receptor gene methylation and maternal behavior on children's early theory of mind abilities

Theory of mind, the ability to represent the mental states of others, is an important social cognitive process, which contributes to the development of social competence. Recent research suggests that interactions between gene and environmental factors, such as oxytocin receptor gene (OXTR) polymorphisms and maternal parenting behavior, may underlie individual differences in children's theory of mind. However, the potential influence of DNA methylation of OXTR remains unclear. The current study investigated the roles of OXTR methylation, maternal behavior, and their statistical interaction on toddlers' early emerging theory of mind abilities. Participants included a community sample of 189 dyads of mothers and their 2- to 3-year-old children, whose salivary DNA was analyzed. Results indicated that more maternal structuring behavior was associated with better performance, on a battery of three theory of mind tasks, while higher OXTR methylation within exon 3 was associated with poorer performance. A significant interaction also emerged, such that OXTR methylation was related to theory of mind among children whose mothers displayed less structuring, when controlling for children's age, sex, ethnicity, number of child-aged siblings, verbal ability, and maternal education. Maternal structuring behavior may buffer the potential negative impact of hypermethylation on OXTR gene expression and function.

BMI1 enhancer polymorphism underlies chromosome 10p12.31 association with childhood acute lymphoblastic leukemia

Genome-wide association studies of childhood acute lymphoblastic leukemia (ALL) have identified regions of association at PIP4K2A and upstream of BMI1 at chromosome 10p12.31-12.2. The contribution of both loci to ALL risk and underlying functional variants remain to be elucidated. We carried out single nucleotide polymorphism (SNP) imputation across chromosome 10p12.31-12.2 in Latino and non-Latino white ALL cases and controls from two independent California childhood leukemia studies, and additional Genetic Epidemiology Research on Aging study controls. Ethnicity-stratified association analyses were performed using logistic regression, with meta-analysis including 3,133 cases (1,949 Latino, 1,184 non-Latino white) and 12,135 controls (8,584 Latino, 3,551 non-Latino white). SNP associations were identified at both BMI1 and PIP4K2A. After adjusting for the lead PIP4K2A SNP, genome-wide significant associations remained at BMI1, and vice-versa (pmeta < 10-10 ), supporting independent effects. Lead SNPs differed by ethnicity at both peaks. We sought functional variants in tight linkage disequilibrium with both the lead Latino SNP among Admixed Americans and lead non-Latino white SNP among Europeans. This pinpointed rs11591377 (pmeta = 2.1 x 10-10 ) upstream of BMI1, residing within a hematopoietic stem cell enhancer of BMI1, and which showed significant preferential binding of the risk allele to MYBL2 (p = 1.73 x 10-5 ) and p300 (p = 1.55 x 10-3 ) transcription factors using binomial tests on ChIP-Seq data from a SNP heterozygote. At PIP4K2A, we identified rs4748812 (pmeta = 1.3 x 10-15 ), which alters a RUNX1 binding motif and demonstrated chromosomal looping to the PIP4K2A promoter. Fine-mapping chromosome 10p12 in a multi-ethnic ALL GWAS confirmed independent associations and identified putative functional variants upstream of BMI1 and at PIP4K2A.

Visualization of Biomedical Data

The rapid increase in volume and complexity of biomedical data requires changes in research, communication, and clinical practices. This includes learning how to effectively integrate automated analysis with high–data density visualizations that clearly express complex phenomena. In this review, we summarize key principles and resources from data visualization research that help address this difficult challenge. We then survey how visualization is being used in a selection of emerging biomedical research areas, including three-dimensional genomics, single-cell RNA sequencing (RNA-seq), the protein structure universe, phosphoproteomics, augmented reality–assisted surgery, and metagenomics. While specific research areas need highly tailored visualizations, there are common challenges that can be addressed with general methods and strategies. Also common, however, are poor visualization practices. We outline ongoing initiatives aimed at improving visualization practices in biomedical research via better tools, peer-to-peer learning, and interdisciplinary collaboration with computer scientists, science communicators, and graphic designers. These changes are revolutionizing how we see and think about our data.

Numb-like (NumbL) downregulation increases tumorigenicity, cancer stem cell-like properties and resistance to chemotherapy

NumbL, or Numb-like, is a close homologue of Numb, and is part of an evolutionary conserved protein family implicated in some important cellular processes. Numb is a protein involved in cell development, in cell adhesion and migration, in asymmetric cell division, and in targeting proteins for endocytosis and ubiquitination. NumbL exhibits some overlapping functions with Numb, but its role in tumorigenesis is not fully known. Here we showed that the downregulation of NumbL alone is sufficient to increase NICD nuclear translocation and induce Notch pathway activation. Furthermore, NumbL downregulation increases epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC)-related gene transcripts and CSC-like phenotypes, including an increase in the CSC-like pool. These data suggest that NumbL can act independently as a tumor suppressor gene. Furthermore, an absence of NumbL induces chemoresistance in tumor cells. An analysis of human tumors indicates that NumbL is downregulated in a variable percentage of human tumors, with lower levels of this gene correlated with worse prognosis in colon, breast and lung tumors. Therefore, NumbL can act as an independent tumor suppressor inhibiting the Notch pathway and regulating the cancer stem cell pool.

Impact of DLK1-DIO3 imprinted cluster hypomethylation in smoker patients with lung cancer

DNA methylation is important for gene expression and genome stability, and its disruption is thought to play a key role in the initiation and progression of cancer and other diseases. The DLK1-DIO3 cluster has been shown to be imprinted in humans, and some of its components are relevant to diverse pathological processes. The purpose of this study was to assess the methylation patterns of the DLK1-DIO3 cluster in patients with lung cancer to study its relevance in the pathogenesis of this disease. We found a characteristic methylation pattern of this cluster in smoking associated lung cancer, as compared to normal lung tissue. This methylation profile is not patent however in lung cancer of never smokers nor in lung tissue of COPD patients. We found 3 deregulated protein-coding genes at this locus: one was hypermethylated (DIO3) and two were hypomethylated (DLK1 and RTL1). Statistically significant differences were also detected in two different families of SNORDs, two miRNA clusters and four lncRNAs (MEG3, MEG8, MEG9 and LINC00524). These findings were validated using data from the cancer genome atlas (TCGA) database. We have then showed an inverse correlation between DNA methylation and expression levels in 5 randomly selected genes. Several targets of miRNAs included in the DLK1-DIO3 cluster have been experimentally verified as tumor suppressors. All of these results suggest that the dysmethylation of the imprinted DLK1-DIO3 cluster could have a relevant role in the pathogenesis of lung cancer in current and former smokers and may be used for diagnostic and/or therapeutic purposes.

Comprehensive Whole DNA Methylome Analysis by Integrating MeDIP-seq and MRE-seq

Understanding the role of DNA methylation often requires accurate assessment and comparison of these modifications in a genome-wide fashion. Sequencing-based DNA methylation profiling provides an unprecedented opportunity to map and compare complete DNA CpG methylomes. These include whole genome bisulfite sequencing (WGBS), Reduced-Representation Bisulfite-Sequencing (RRBS), and enrichment-based methods such as MeDIP-seq, MBD-seq, and MRE-seq. An investigator needs a method that is flexible with the quantity of input DNA, provides the appropriate balance among genomic CpG coverage, resolution, quantitative accuracy, and cost, and comes with robust bioinformatics software for analyzing the data. In this chapter, we describe four protocols that combine state-of-the-art experimental strategies with state-of-the-art computational algorithms to achieve this goal. We first introduce two experimental methods that are complementary to each other. MeDIP-seq, or methylation-dependent immunoprecipitation followed by sequencing, uses an anti-methylcytidine antibody to enrich for methylated DNA fragments, and uses massively parallel sequencing to reveal identity of enriched DNA. MRE-seq, or methylation-sensitive restriction enzyme digestion followed by sequencing, relies on a collection of restriction enzymes that recognize CpG containing sequence motifs, but only cut when the CpG is unmethylated. Digested DNA fragments enrich for unmethylated CpGs at their ends, and these CpGs are revealed by massively parallel sequencing. The two computational methods both implement advanced statistical algorithms that integrate MeDIP-seq and MRE-seq data. M&M is a statistical framework to detect differentially methylated regions between two samples. methylCRF is a machine learning framework that predicts CpG methylation levels at single CpG resolution, thus raising the resolution and coverage of MeDIP-seq and MRE-seq to a comparable level of WGBS, but only incurring a cost of less than 5% of WGBS. Together these methods form an effective, robust, and affordable platform for the investigation of genome-wide DNA methylation.

Loss of DNA methylation in zebrafish embryos activates retrotransposons to trigger antiviral signaling

Complex cytoplasmic nucleotide-sensing mechanisms can recognize foreign DNA based on a lack of methylation and initiate an immune response to clear the infection. Zebrafish embryos with global DNA hypomethylation caused by mutations in the ubiquitin-like with PHD and ring finger domains 1 (uhrf1) or DNA methyltransferase 1 (dnmt1) genes exhibit a robust interferon induction characteristic of the first line of defense against viral infection. We found that this interferon induction occurred in non-immune cells and examined whether intracellular viral sensing pathways in these cells were the trigger. RNA-seq analysis of uhrf1 and dnmt1 mutants revealed widespread induction of Class I retrotransposons and activation of cytoplasmic DNA viral sensors. Attenuating Sting, phosphorylated Tbk1 and, importantly, blocking reverse transcriptase activity suppressed the expression of interferon genes in uhrf1 mutants. Thus, activation of transposons in cells with global DNA hypomethylation mimics a viral infection by activating cytoplasmic DNA sensors. This suggests that antiviral pathways serve as surveillance of cells that have derepressed intragenomic parasites due to DNA hypomethylation.

Comparative Epigenomic Profiling of the DNA Methylome in Mouse and Zebrafish Uncovers High Interspecies Divergence

The DNA methylation landscape is dynamically patterned during development and distinct methylation patterns distinguish healthy from diseased cells. However, whether tissue-specific methylation patterns are conserved across species is not known. We used comparative methylome analysis of base-resolution DNA methylation profiles from the liver and brain of mouse and zebrafish generated by reduced representation bisulfite sequencing to identify the conserved and divergent aspects of the methylome in these commonly used vertebrate model organisms. On average, 24% of CpGs are methylated in mouse livers and the pattern of methylation was highly concordant among four male mice from two different strains. The same level of methylation (24.2%) was identified in mouse brain. In striking contrast, zebrafish had 63 and 70% of CpG methylation in the liver and brain, respectively. This is attributed, in part, to the higher percentage of the zebrafish genome occupied by transposable elements (52% vs. 45% in mice). Thus, the species identity was more significant in determining methylome patterning than was the similarity in organ function. Conserved features of the methylome across tissues and species was the exclusion of methylation from promoters and from CpG islands near transcription start sites, and the clustering of methylated CpGs in gene bodies and intragenic regions. These data suggest that DNA methylation reflects species-specific genome structure, and supports the notion that DNA methylation in non-promoter regions may contribute to genome evolution.

Combining MeDIP-seq and MRE-seq to investigate genome-wide CpG methylation

DNA CpG methylation is a widespread epigenetic mark in high eukaryotes including mammals. DNA methylation plays key roles in diverse biological processes such as X chromosome inactivation, transposable element repression, genomic imprinting, and control of gene expression. Recent advancements in sequencing-based DNA methylation profiling methods provide an unprecedented opportunity to measure DNA methylation in a genome-wide fashion, making it possible to comprehensively investigate the role of DNA methylation. Several methods have been developed, such as Whole Genome Bisulfite Sequencing (WGBS), Reduced Representation Bisulfite Sequencing (RRBS), and enrichment-based methods including Methylation Dependent ImmunoPrecipitation followed by sequencing (MeDIP-seq), methyl-CpG binding domain (MBD) protein-enriched genome sequencing (MBD-seq), methyltransferase-directed Transfer of Activated Groups followed by sequencing (mTAG), and Methylation-sensitive Restriction Enzyme digestion followed by sequencing (MRE-seq). These methods differ by their genomic CpG coverage, resolution, quantitative accuracy, cost, and software for analyzing the data. Among these, WGBS is considered the gold standard. However, it is still a cost-prohibitive technology for a typical laboratory due to the required sequencing depth. We found that by integrating two enrichment-based methods that are complementary in nature (i.e., MeDIP-seq and MRE-seq), we can significantly increase the efficiency of whole DNA methylome profiling. By using two recently developed computational algorithms (i.e., M&M and methylCRF), the combination of MeDIP-seq and MRE-seq produces genome-wide CpG methylation measurement at high coverage and high resolution, and robust predictions of differentially methylated regions. Thus, the combination of the two enrichment-based methods provides a cost-effective alternative to WGBS. In this article we describe both the experimental protocols for performing MeDIP-seq and MRE-seq, and the computational protocols for running M&M and methylCRF.