DNMT inhibitors reverse a specific signature of aberrant promoter DNA methylation and associated gene silencing in AML

<b>Background</b>. Myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) are neoplastic disorders of hematopoietic stem cells. DNA methyltransferase inhibitors (DNMTi), 5-azacytidine (AzaC) and 5-aza-2’-deoxycytidine (Decitabine), benefit some MDS/AML patients. However, the role of DNMTi-induced DNA hypomethylation in regulation of gene expression in AML is unclear.<p></p> <b>Results. </b> We compared the effects of AzaC on DNA methylation and gene expression using whole-genome single-nucleotide bisulfite-sequencing (WGBS) and RNA-sequencing in OCI-AML3 (AML3) cells. For data analysis, we used an approach recently developed for discovery of differential patterns of DNA methylation associated with changes in gene expression, that is tailored to single-nucleotide bisulfite-sequencing data (Washington University Interpolated Methylation Signatures (WIMSi)). By this approach, a subset of genes upregulated by AzaC was found to be characterized by AzaC-induced signature methylation loss flanking the transcription start site. These genes are enriched for genes increased in methylation and decreased in expression in AML3 cells compared to normal hematopoietic stem and progenitor cells. Moreover, these genes are preferentially upregulated by Decitabine in human primary AML blasts, and control cell proliferation, death and development. <p></p> <b>Conclusions.</b> Our WGBS and WIMSi data analysis approach has identified a set of genes whose is methylation and silencing in AML is reversed by DNMTi. These genes are good candidates for direct regulation by DNMTi, and their reactivation by DNMTi may contribute to therapeutic activity. This study also demonstrates the ability of WIMSi to reveal relationships between DNA methylation and gene expression, based on single-nucleotide bisulfite-sequencing and RNA-seq data.<p></p&gt

Amnion as a surrogate tissue reporter of the effects of maternal preeclampsia on the fetus

We described the study design, detailed analytical methods, and verification results in the supporting information file. (DOCX 21.2 MB

De novo DNA demethylation and non-coding transcription define active intergenic regulatory elements

Deep sequencing of mammalian DNA methylomes has uncovered a previously unpredicted number of discrete hypomethylated regions in intergenic space (iHMRs). Here, we combined whole genome bisulfite sequencing data with extensive gene-expression and chromatin-state data to define functional classes of iHMRs, and to reconstruct the dynamics of their establishment in a developmental setting. Comparing HMR profiles in embryonic stem and primary blood cells, we show that iHMRs mark an exclusive subset of active DNase hypersensitive sites (DHS), and that both developmentally constitutive and cell-type specific iHMRs display chromatin states typical of distinct regulatory elements. We also observe that iHMR changes are more predictive of nearby gene activity than the promoter HMR itself, and that expression of non-coding RNAs within the iHMR accompanies full activation and complete demethylation of mature B cell enhancers. Conserved sequence features corresponding to iHMR transcript start sites, including a discernable TATAA motif, suggest a conserved, functional role for transcription in these regions. Similarly, we explored both primate-specific and human-population variation at iHMRs, finding that while enhancer iHMRs are more variable in sequence and methylation status than any other functional class, conservation of the TATA box is highly predictive of iHMR maintenance, reflecting the impact of sequence plasticity and transcriptional signals on iHMR establishment. Overall, our analysis allowed us to construct a 3-step timeline in which 1) intergenic DHS are pre-established in the stem cell, 2) partial demethylation of blood specific intergenic DHSs occurs in blood progenitors, and 3) complete iHMR formation and transcription coincide with enhancer activation in lymphoid-specified cells

Exploring Patterns of Epigenetic Information With Data Mining Techniques

[Abstract] Data mining, a part of the Knowledge Discovery in Databases process (KDD), is the process of extracting patterns from large data sets by combining methods from statistics and artificial intelligence with database management. Analyses of epigenetic data have evolved towards genome-wide and high-throughput approaches, thus generating great amounts of data for which data mining is essential. Part of these data may contain patterns of epigenetic information which are mitotically and/or meiotically heritable determining gene expression and cellular differentiation, as well as cellular fate. Epigenetic lesions and genetic mutations are acquired by individuals during their life and accumulate with ageing. Both defects, either together or individually, can result in losing control over cell growth and, thus, causing cancer development. Data mining techniques could be then used to extract the previous patterns. This work reviews some of the most important applications of data mining to epigenetics.Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo; 209RT-0366Galicia. Consellería de Economía e Industria; 10SIN105004PRInstituto de Salud Carlos III; RD07/0067/000

LRpath analysis reveals common pathways dysregulated via DNA methylation across cancer types

Abstract Background The relative contribution of epigenetic mechanisms to carcinogenesis is not well understood, including the extent to which epigenetic dysregulation and somatic mutations target similar genes and pathways. We hypothesize that during carcinogenesis, certain pathways or biological gene sets are commonly dysregulated via DNA methylation across cancer types. The ability of our logistic regression-based gene set enrichment method to implicate important biological pathways in high-throughput data is well established. Results We developed a web-based gene set enrichment application called LRpath with clustering functionality that allows for identification and comparison of pathway signatures across multiple studies. Here, we employed LRpath analysis to unravel the commonly altered pathways and other gene sets across ten cancer studies employing DNA methylation data profiled with the Illumina HumanMethylation27 BeadChip. We observed a surprising level of concordance in differential methylation across multiple cancer types. For example, among commonly hypomethylated groups, we identified immune-related functions, peptidase activity, and epidermis/keratinocyte development and differentiation. Commonly hypermethylated groups included homeobox and other DNA-binding genes, nervous system and embryonic development, and voltage-gated potassium channels. For many gene sets, we observed significant overlap in the specific subset of differentially methylated genes. Interestingly, fewer DNA repair genes were differentially methylated than expected by chance. Conclusions Clustering analysis performed with LRpath revealed tightly clustered concepts enriched for differential methylation. Several well-known cancer-related pathways were significantly affected, while others were depleted in differential methylation. We conclude that DNA methylation changes in cancer tend to target a subset of the known cancer pathways affected by genetic aberrations.http://deepblue.lib.umich.edu/bitstream/2027.42/112789/1/12864_2012_Article_4373.pd

Transcriptional truncation of the long coding imprinted gene Usp29

© 2016 He et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Usp29 (Ubiquitin-specific protease 29) is a paternally expressed gene located upstream of another imprinted gene Peg3. In the current study, the transcription of this long coding gene spanning a 250-kb genomic distance was truncated using a knockin allele. According to the results, paternal transmission of the mutant allele resulted in reduced body and litter sizes whereas the maternal transmission caused no obvious effects. In the paternal mutant, the expression levels of Usp29 were reduced to 14-18% level of the wild-type littermates due to the Poly-A signal included in the knockin cassette. Expression analyses further revealed an unusual female-specific up-regulation of the adjacent imprinted gene Zfp264 in the mutant. Consistent with this, the promoter of Zfp264 was hypomethylated only in the female mutant. Interestingly, this female-specific hypomethylation by the knockin allele was not detected in the offspring of an interspecific crossing, indicating its sensitivity to genetic background. Overall, the results suggest that the transcription of Usp29 may be involved in DNA methylation setting of Zfp264 promoter in a sex-specific manner

Differential DNA methylation profiles modulating phenotypes : Regions of tissue-specific DNA methylation and their relation to gene expression, their evolutionary conservation and their application as molecular biomarkers

Tissue- specific DNA methylation plays a major regulatory role. The association of increased tissue-specific DNA methylation and gene silencing is widely accepted despite the lack of experimental evidence. I have approached this topic in two complementary directions. First, using direct sequencing of bisulfite-converted DNA and semiquantitative RT-PCR, I show that increased methylation correlates with decreased expression of the cognate transcript in healthy adult tissues and primary cells in 16 out of 43 (39%) tissue-specific differentially methylated regions (T-DMRs) located at the 5’-UTR of annotated genes. In the second approach, I have first determined the genome-wide expression profiles of fetal and healthy adult human lung and then studied the methylation status of 43 differentially expressed genes. Among them, highly methylated 5’-UTR regions correlate with decreased expression levels in 19% of the cases. Furthermore, this approach allowed the discovery of four differentially expressed genes in fetal lung (MEOX2, MDK, LAPTM5 and FGFR3), whose differential methylation arise as potential biomarker for lung cancer. Next, I have studied the conservation of T-DMRs throughout the evolution. First, using direct sequencing of bisulfite-converted DNA, I show that the majority (69.4%) out of 61 orthologous regions in human and mouse differ by less than 20% in their methylation, indicating significant conservation. Additionally, by comparative DNA methylation analysis of three different gene duplication events leading to functional gene families, unprocessed and processed pseudogenes, I show that for genes that evolved recently and for some unprocessed pseudogenes, tissue-specific DNA methylation and RNA expression are conserved upon duplication. Finally, I have studied the interaction of genetic and epigenetic alterations in modulating phenotypes in non-oncogenic diseases. The RARB gene appears highly methylated in patients with familial partial lipodystrophy (FPLD) compared to progeria patients and healthy controls. This differential methylation might explain the different phenotypes observed despite similar genetic backgrounds. Altogether, this work presents vast experimental evidence supporting the hypothesis of differential DNA methylation patterns influencing, and in may cases determining, phenotypes in healthy and diseased tissues

Targeted Epigenetic Editing to Increase Adult Pancreatic Β-Cell Proliferation

β-cell replacement therapy is potentially a curative approach in treating diabetes, as demonstrated by the success of pancreatic islet transplantation in type 1 diabetes. However, there are an insufficient number of organ donors to meet the demand of this disease, which is increasing in prevalence. One strategy to increase the supply of human β-cells for transplantation in type 1 diabetics, or to increase residual β-cell mass in type 2 diabetics, is to induce human β-cell replication. This strategy has not been implemented clinically because adult human β-cells are largely quiescent and the capacity for proliferation decreases with age. I hypothesized that changes in DNA methylation contribute to the age-related decline in proliferative capacity in human β-cells, and that altering the DNA methylome in a targeted manner could improve proliferative capacity. To investigate this hypothesis, I sought to profile the β-cell across the human lifespan, and to develop tools that permit targeted DNA methylation modifications and efficiency in measuring DNA methylation. I conducted RNA-Seq and whole-genome bisulfite sequencing (WGBS) to profile the aging human β-cell transcriptome and DNA methylome. I found that there are significant changes in gene expression with age, and in DNA methylation, particularly at islet-specific active enhancers. Further, I developed transcription activator-like effector (TALE) fusion proteins conjugated to DNA methyltransferases (DNMTs) and demonstrated that targeting TALE-DNMTs to the promoter of the CDKN2A locus, encoding the cell cycle inhibitor p16, increases proliferation in primary human fibroblasts. Finally, I developed BisPCR2, a novel technique for preparing targeted bisulfite next-generation sequencing libraries, which greatly improves the efficiency in which DNA methylation can be measured at target regions. I demonstrated the utility of this tool to validate genome-wide findings of type 2 diabetes CpG risk loci. Together, these novel datasets and epigenetic tools poise the β-cell regeneration field to investigate targeted epigenetic modifications as a strategy to improve proliferative capacity of adult human β-cells