Aberrant DNA methylation distorts developmental trajectories in atypical teratoid/rhabdoid tumors

Atypical teratoid/rhabdoid tumors (AT/RTs) are pediatric brain tumors known for their aggressiveness and aberrant but still unresolved epigenetic regulation. To better understand their malignancy, we investigated how AT/RT-specific DNA hypermethylation was associated with gene expression and altered transcription factor binding and how it is linked to upstream regulation. Medulloblastomas, choroid plexus tumors, pluripotent stem cells, and fetal brain were used as references. A part of the genomic regions, which were hypermethylated in AT/RTs similarly as in pluripotent stem cells and demethylated in the fetal brain, were targeted by neural transcriptional regulators. AT/RT-unique DNA hypermethylation was associated with polycomb repressive complex 2 and linked to suppressed genes with a role in neural development and tumorigenesis. Activity of the several NEUROG/NEUROD pioneer factors, which are unable to bind to methylated DNA, was compromised via the suppressed expression or DNA hypermethylation of their target sites, which was also experimentally validated for NEUROD1 in medulloblastomas and AT/RT samples. These results highlight and characterize the role of DNA hypermethylation in AT/RT malignancy and halted neural cell differentiation.

Development of disease-specific growth charts for Korean children with Beckwith-Wiedemann syndrome

Beckwith-Wiedemann syndrome (BWS) is an epigenetic overgrowth syndrome. Despite its distinctive growth pattern, the detailed growth trajectories of children with BWS remain largely unknown. We retrospectively analyzed 413 anthropometric measurements over an average of 4.4 years of follow-up in 51 children with BWS. We constructed sex-specific percentile curves for height, weight, and head circumference using a generalized additive model for location, scale, and shape. Males with BWS exhibited greater height at all ages evaluated, weight before the age of 10, and head circumference before the age of 9 than those of the general population. Females with BWS showed greater height before the age of 7, weight before the age of 4.5, and head circumference before the age of 7 than those of the general population. At the latest follow-up visit at a mean 8.4 years of age, bone age was significantly higher than chronological age. Compared to paternal uniparental disomy (pUPD), males with imprinting center region 2-loss of methylation (IC2-LOM) had higher standard deviation score (SDS) for height and weight, while females with IC2-LOM showed larger SDS for head circumference. These disease-specific growth charts can serve as valuable tools for clinical monitoring of children with BWS.

Methylation‑sensitive restriction enzyme‑droplet digital PCR assay for the one‑step highly sensitive analysis of DNA methylation hotspots

DNA methylation is an epigenetic modification that plays a key role in several cellular processes mediating the fine regulation of gene expression. Aberrant DNA methylation is observed in a wide range of pathologies, including cancer. Since these DNA modifications are transferred to the cell progenies and are stable over the time, the analysis of DNA methylation status has been proposed for diagnostic and prognostic purposes in cancer. Currently, DNA bisulfite conversion is the gold standard method for the high‑throughput analysis of DNA methylation alterations. However, bisulfite treatment induces DNA fragmentation affecting its quality for the downstream analyses. In this field, it is mandatory to identify novel methods to overcome the limits of conventional approaches. In the present study, the Methylation‑Sensitive Restriction Enzyme‑droplet digital PCR (MSRE‑ddPCR) assay was developed as a novel sensitive method for the analysis of DNA methylation of short genomic regions, combining the MSRE assay with the high‑sensitivity ddPCR and using an exogenous methylation sequence as control. Setup and validation experiments were performed analyzing a methylation hotspot of the Solute Carrier Family 22 Member 17 in DNA samples derived from melanoma cell lines as well as from tissues and serum samples obtained from patients with melanoma and healthy controls. Compared with the standard MSRE approaches, the MSRE‑ddPCR assay is more appropriate for the analysis of DNA methylation (methDNA) in samples with low amounts of DNA (up to 0.651 ng) showing a greater sensitivity. These findings suggested the potential clinical application of MSRE‑ddPCR paving the way to the analysis of other methDNA hotspots in different tumors.

Divergent selection for feed efficiency in pigs altered the duodenum transcriptomic response to feed intake and its DNA methylation profiles

Feed efficiency is a trait of interest in pigs as it contributes to lowering the ecological and economical costs of pig production. A divergent genetic selection experiment from a Large White pig population was performed for 10 generations, leading to pig lines with relatively low- (LRFI) and high- (HRFI) residual feed intake (RFI). Feeding behavior and metabolic differences have been previously reported between the two lines. We hypothesized that part of these differences could be related to differential sensing and absorption of nutrients in the proximal intestine. We investigated the duodenum transcriptome and DNA methylation profiles comparing overnight fasting with ad libitum feeding in LRFI and HRFI pigs (n = 24). We identified 1,106 differentially expressed genes between the two lines, notably affecting pathways of the transmembrane transport activity and related to mitosis or chromosome separation. The LRFI line showed a greater transcriptomic response to feed intake than the HRFI line. Feed intake affected genes from both anabolic and catabolic pathways in the pig duodenum, such as rRNA production and autophagy. Several nutrient transporter and tight junction genes were differentially expressed between lines and/or by short-term feed intake. We also identified 409 differentially methylated regions in the duodenum mucosa between the two lines, while this epigenetic mark was less affected by feeding. Our findings highlighted that the genetic selection for feed efficiency in pigs changed the transcriptome profiles of the duodenum, and notably its response to feed intake, suggesting key roles for this proximal gut segment in mechanisms underlying feed efficiency.NEW & NOTEWORTHY The duodenum is a key organ for the hunger/satiety loop and nutrient sensing. We investigated how the duodenum transcriptome and DNA methylation profiles are affected by feed intakes in pigs. We observed thousands of changes in gene expression levels between overnight-fasted and fed pigs in high-feed efficiency pig lines, but almost none in the related low-feed efficiency pig line.

Multi-omics reveals the switch role of abnormal methylation in the regulation of decidual macrophages function in recurrent spontaneous abortion

RSA, recurrent spontaneous abortion, often causes serious physical damage and psychological pressure in reproductive women with unclarified pathogenesis. Abnormal function of decidual cells and aberrant DNA methylation have been reported to cause RSA, but their association remains unclear. Here, we integrated transcriptome, DNA methylome, and scRNA-seq to clarify the regulatory relationship between DNA methylation and decidual cells in RSA. We found that DNA methylation mainly influenced the function of decidual macrophages (DMs), of which four hub genes, HLA-A, HLA-F, SQSTM1/P62, and Interferon regulatory factor 7 (IRF7), related to 22 hypomethylated CpG sites, regulated 16 hub pathways to participate in RSA pathogenesis. In particular, using transcription factor analysis, it is suggested that the upregulation of IRF7 transcription was associated with enhanced recruitment of the transcription factor STAT1 by the hypomethylated promoter region of IRF7. As the current research on DNA methylation of macrophages in the uterine microenvironment of RSA is still blank, our systematic picture of abnormal DNA methylation in regulating DM function provides new insights into the role of DNA methylation in RSA occurrence, which may aid in further prevention and treatment of RSA.

Untangling the gordian knot: The intertwining interactions between developmental hormone signaling and epigenetic mechanisms in insects

Hormones control developmental and physiological processes, often by regulating the expression of multiple genes simultaneously or sequentially. Crosstalk between hormones and epigenetics is pivotal to dynamically coordinate this process. Hormonal signals can guide the addition and removal of epigenetic marks, steering gene expression. Conversely, DNA methylation, histone modifications and non-coding RNAs can modulate regional chromatin structure and accessibility and regulate the expression of numerous (hormone-related) genes. Here, we provide a review of the interplay between the classical insect hormones, ecdysteroids and juvenile hormones, and epigenetics. We summarize the mode-of-action and roles of these hormones in post-embryonic development, and provide a general overview of epigenetic mechanisms. We then highlight recent advances on the interactions between these hormonal pathways and epigenetics, and their involvement in development. Furthermore, we give an overview of several 'omics techniques employed in the field. Finally, we discuss which questions remain unanswered and possible avenues for future research.

Three-year study of DNA cytosine methylation dynamics in transplanted Malbec grapevines

DNA cytosine methylation, an epigenetic mechanism involved in gene regulation and genome stability, remains poorly understood in terms of its role under changing environmental conditions. Previous research using methylation-sensitive amplified polymorphism (MSAP) markers in a Vitis vinifera L. cv. Malbec clone showed vineyard-specific DNA methylation polymorphism, but no change in overall methylation levels. To complement these findings, the present study investigates the intra-seasonal epigenetic dynamics between genetically identical plants grown in different vineyards through a transplanting experiment. Cuttings of the same clone, showing differential methylation patterns imposed by the vineyard of origin (Agrelo and Gualtallary), were cultivated in a common vineyard (Lunlunta). Using high-performance liquid chromatography-ultraviolet detection, the quantification of global DNA 5-methylcytosine (5-mC) levels revealed relatively low overall 5-mC percentages in grapevines, with higher levels in Agrelo (5.8%) compared to Gualtallary plants (3.7%). The transplanted plants maintained the 5-mC levels differences between vineyards (9.8% vs 6.2%), which equalized in subsequent seasons (7.5% vs 7%). Additionally, the study examined 5-mC polymorphism using MSAP markers in Lunlunta transplanted plants over three seasons. The observed differences between vineyards in MSAP patterns during the initial growing season gradually diminished, suggesting a reprogramming of the hemimethylated pattern following implantation in the common vineyard. In contrast, the non-methylated pattern exhibited greater stability, indicating a potential memory effect. Overall, this study provides valuable insights into the dynamic nature of DNA methylation in grapevines under changing environmental conditions, with potential implications for crop management and breeding strategies.

Identification of AtALKBH1A and AtALKBH1D as DNA N6-adenine demethylases in Arabidopsis thaliana

DNA N6-methyladenine (6 mA) has recently been discovered as a novel DNA modification in animals and plants. In mammals, AlkB homolog 1 (ALKBH1) has been identified as a DNA 6 mA demethylase. ALKBH1 tightly controls the DNA 6 mA methylation level of mammalian genomes and plays important role in regulating gene expression. DNA 6 mA methylation has also been reported to exist in plant genomes, however, the plant DNA 6 mA demethylases and their function remain largely unknown. Here we identify homologs of ALKBH1 as DNA 6 mA demethylases in Arabidopsis. We discover that there are four homologs of ALKBH1, AtALKBH1A, AtALKBH1B, AtALKBH1C and AtALKBH1D, in Arabidopsis. In vitro enzymatic activity studies reveal that AtALKBH1A and 1D can efficiently erase DNA 6 mA methylation. Loss of function of AtALKBH1A and AtALKBH1D causes elevated DNA 6 mA methylation levels in vivo. atalkbh1a/1d mutant displays delayed seed gemination. Based on our RNA-seq data, we find some regulators of seed gemination are dysregulated in atalkbh1a/1d, and the dysregulation is correlated with changes of DNA 6 mA methylation levels. This study identifies plant DNA 6 mA demethylases and reports the function of DNA 6 mA methylation in regulating seed germination.

The influence of serum selenium in differential epigenetic and transcriptional regulation of CPT1B gene in women with obesity

INTRODUCTION

The increasing prevalence of obesity has become a major health problem worldwide. The causes of obesity are multifactorial and could be influenced by dietary patterns and genetic factors. Obesity has been associated with a decrease in micronutrient intake and consequently decreased blood concentrations. Selenium is an essential micronutrient for human health, and its metabolism could be affected by obesity, especially severe obesity. This study aimed to identify differential methylation genes associated with serum selenium concentration in women with and without obesity.

METHODOLOGY

Thirty-four patients were enrolled in the study and divided into two groups: Obese (Ob) n = 20 and Non-Obese (NOb) n = 14, according to the Body Mass Index (BMI). Anthropometry, body composition, serum selenium, selenium intake, and biochemical parameters were evaluated. DNA extraction and bisulfite conversion were performed to hybridize the samples on the 450k Methylation Chip Infinium Beadchip (Illumina). Bioinformatics analysis was performed using the R program and the Champ package. The differentially methylated regions (DMRs) were identified using the Bumphunter method. In addition, logarithmic conversion was performed for the analysis of serum selenium and methylation.

RESULTS

In the Ob group, the body weight, BMI, fat mass, and free fat mass were higher than in the NOb group, as expected. Interestingly, the serum selenium was lower in the Ob than in the NOb group without differences in selenium intake. One DMR corresponding to the CPT1B gene, involved in lipid oxidation, was related to selenium levels. This region was hypermethylated in the Ob group, indicating that the intersection between selenium deficiency and hypermethylation could influence the expression of the CPT1B gene. The transcriptional analysis confirmed the lower expression of the CPT1B gene in the Ob group.

CONCLUSION

Studies connecting epigenetics to environmental factors could offer insights into the mechanisms involving the expression of genes related to obesity and its comorbidities. Here we demonstrated that the mineral selenium might play an essential role in lipid oxidation via epigenetic and transcriptional regulation of the CPT1B gene in obesity.

Chromatinopathies: insight in clinical aspects and underlying epigenetic changes

Chromatinopathies (CPs), a group of rare inborn defects characterized by chromatin state imbalance, have evolved from initially resembling Cornelia de Lange syndrome to encompass a wide array of genetic diseases with diverse clinical presentations. The CPs classification now includes human developmental disorders caused by germline mutations in epigenes, genes that regulate the epigenome. Recent advances in next-generation sequencing have enabled the association of 154 epigenes with CPs, revealing distinctive DNA methylation patterns known as episignatures.It has been shown that episignatures are unique for a particular CP or share similarities among specific CP subgroup. Consequently, these episignatures have emerged as promising biomarkers for diagnosing and treating CPs, differentiating subtypes, evaluating variants of unknown significance, and facilitating targeted therapies tailored to the underlying epigenetic dysregulation.The following review was conducted to collect, summarize, and analyze data regarding CPs in such aspects as clinical evaluation encompassing long-term patient care, underlying epigenetic changes, and innovative molecular and bioinformatic methodologies that have been devised for the assessment of CPs. We have also shed light on promising novel treatment options that have surfaced in recent research and presented a synthesis of ongoing clinical trials, contributing to the current understanding of the dynamic and evolving nature of CPs investigation.

Genome-wide DNA methylation dynamics following recent polyploidy in the allotetraploid Tragopogon miscellus (Asteraceae)

Polyploidy is an important evolutionary force, yet epigenetic mechanisms, such as DNA methylation, that regulate genome-wide expression of duplicated genes remain largely unknown. Here, we use Tragopogon (Asteraceae) as a model system to discover patterns and temporal dynamics of DNA methylation in recently formed polyploids. The naturally occurring allotetraploid Tragopogon miscellus formed in the last 95-100 yr from parental diploids Tragopogon dubius and T. pratensis. We profiled the DNA methylomes of these three species using whole-genome bisulfite sequencing. Genome-wide methylation levels in T. miscellus were intermediate between its diploid parents. However, nonadditive CG and CHG methylation occurred in transposable elements (TEs), with variation among TE types. Most differentially methylated regions (DMRs) showed parental legacy, but some novel DMRs were detected in the polyploid. Differentially methylated genes (DMGs) were also identified and characterized. This study provides the first assessment of both overall and locus-specific patterns of DNA methylation in a recent natural allopolyploid and shows that novel methylation variants can be generated rapidly after polyploid formation. Together, these results demonstrate that mechanisms to regulate duplicate gene expression may arise soon after allopolyploid formation and that these mechanisms vary among genes.

DNA methylation of imprint control regions associated with Alzheimer's disease in non-Hispanic Blacks and non-Hispanic Whites

Alzheimer's disease (AD) prevalence is twice as high in non-Hispanic Blacks (NHBs) as in non-Hispanic Whites (NHWs). The objective of this study was to determine whether aberrant methylation at imprint control regions (ICRs) is associated with AD. Differentially methylated regions (DMRs) were bioinformatically identified from whole-genome bisulfite sequenced DNA derived from brain tissue of 9 AD (5 NHBs and 4 NHWs) and 8 controls (4 NHBs and 4 NHWs). We identified DMRs located within 120 regions defined as candidate ICRs in the human imprintome ( https://genome.ucsc.edu/s/imprintome/hg38.AD.Brain_track ). Eighty-one ICRs were differentially methylated in NHB-AD, and 27 ICRs were differentially methylated in NHW-AD, with two regions common to both populations that are proximal to the inflammasome gene, NLRP1, and a known imprinted gene, MEST/MESTIT1. These findings indicate that early developmental alterations in DNA methylation of regions regulating genomic imprinting may contribute to AD risk and that this epigenetic risk differs between NHBs and NHWs.

Association of Cadherin-Related Family Member 1 with Traumatic Brain Injury

The cadherin family plays a pivotal role in orchestrating synapse formation in the central nervous system. Cadherin-related family member 1 (CDHR1) is a photoreceptor-specific calmodulin belonging to the expansive cadherin superfamily. However, its role in traumatic brain injury (TBI) remains largely unknown. CDHR1 expression across various brain tissue sites was analyzed using the GSE104687 dataset. Employing a summary-data-based Mendelian Randomization (SMR) approach, integrated analyses were performed by amalgamating genome-wide association study abstracts from TBI with public data on expressed quantitative trait loci and DNA methylation QTL from both blood and diverse brain tissues. CDHR1 expression and localization in different brain tissues were meticulously delineated using western blotting, immunohistochemistry, and enzyme-linked immunosorbent assay. CDHR1 expression was consistently elevated in the TBI group compared to that in the sham group across multiple tissues. The inflammatory response emerged as a crucial biological mechanism, and pro-inflammatory and anti-inflammatory factors were not expressed in either group. Integrated SMR analyses encompassing both blood and brain tissues substantiated the heightened CDHR1 expression profiles, with methylation modifications emerging as potential contributing factors for increased TBI risk. This was corroborated by western blotting and immunohistochemistry, confirming augmented CDHR1 expression following TBI. This multi-omics-based genetic association study highlights the elevated TBI risk associated with CDHR1 expression coupled with putative methylation modifications. These findings provide compelling evidence for future targeted investigations and offer promising avenues for developing interventional therapies for TBI.

Evaluating the link between DIO3-FA27 promoter methylation, biochemical indices, and heart failure progression

BACKGROUND

Heart failure (HF) is a disease that poses a serious threat to individual health, and DNA methylation is an important mechanism in epigenetics, and its role in the occurrence and development of the disease has attracted more and more attention. The aim of this study was to evaluate the link between iodothyronine deiodinase 3 promoter region fragment FA27 (DIO3-FA27) methylation levels, biochemical indices, and HF.

RESULTS

The methylation levels of DIO3-FA27_CpG_11.12 and DIO3-FA27_CpG_23.24 significantly differed in HF patients with different degrees. Multivariate logistic regression analysis indicated that the relative HF risk in the third and fourth quartiles of activated partial thromboplastin time and fibrin degradation products. The results of the restricted cubic spline model showed that the methylation levels of DIO3-FA 27_CpG_11.12 and DIO3-FA 27_CpG_23.24 were associated with coagulation indicators, liver function, renal function, and blood routine.

CONCLUSIONS

Based on the differential analysis of CpG methylation levels based on DIO3-FA27, it was found that biochemical indicators combined with DIO3-FA27 promoter DNA methylation levels could increase the risk of worsening the severity classification of HF patients, which provided a solid foundation and new insights for the study of epigenetic regulation mechanisms in patients with HF.

Comprehensive DNA methylation profiling by MeDIP-NGS identifies potential genes and pathways for epithelial ovarian cancer

Ovarian cancer, among all gynecologic malignancies, exhibits the highest incidence and mortality rate, primarily because it is often presents with non-specific or no symptoms during its early stages. For the advancement of Ovarian Cancer Diagnosis, it is crucial to identify the potential molecular signatures that could significantly differentiate between healthy and ovarian cancerous tissues and can be used further as a diagnostic biomarker for detecting ovarian cancer. In this study, we investigated the genome-wide methylation patterns in ovarian cancer patients using Methylated DNA Immunoprecipitation (MeDIP-Seq) followed by NGS. Identified differentially methylated regions (DMRs) were further validated by targeted bisulfite sequencing for CpG site-specific methylation profiles. Furthermore, expression validation of six genes by Quantitative Reverse Transcriptase-PCR was also performed. Out of total 120 differentially methylated genes (DMGs), 68 genes were hypermethylated, and 52 were hypomethylated in their promoter region. After analysis, we identified the top 6 hub genes, namely POLR3B, PLXND1, GIGYF2, STK4, BMP2 and CRKL. Interestingly we observed Non-CpG site methylation in the case of POLR3B and CRKL which was statistically significant in discriminating ovarian cancer samples from normal controls. The most significant pathways identified were focal adhesion, the MAPK signaling pathway, and the Ras signaling pathway. Expression analysis of hypermethylated genes was correlated with the downregulation of the genes. POLR3B and GIGYF2 turned out to be the novel genes associated with the carcinogenesis of EOC. Our study demonstrated that methylation profiling through MeDIP-sequencing has effectively identified six potential hub genes and pathways that might exacerbate our understanding of underlying molecular mechanisms of ovarian carcinogenesis.

Association of GAL-8 promoter methylation levels with coronary plaque inflammation

BACKGROUND AND AIMS

Coronary heart disease (CHD) is a condition that carries a high risk of mortality and is associated with aging. CHD is characterized by the chronic inflammatory response of the coronary intima. Recent studies have shown that the methylation level of blood mononuclear cell DNA is closely associated with adverse events in CHD, but the roles and mechanisms of DNA methylation in CHD remain elusive.

METHODS AND RESULTS

In this study, the DNA methylation status within the epigenome of human coronary tissue in the sudden coronary death (SCD) group and control (CON) group of coronary heart disease was analyzed using the Illumina® Infinium Methylation EPIC BeadChip (850 K chip), resulting in the identification of a total of 2553 differentially methylated genes (DMGs). The differentially methylated genes were then subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and significant differential DNA methylation was found. Among the differentially hypomethylated genes were GAL-8, LTF, and RFPL3, while the highly methylated genes were TMEM9B, ANK3, and C6orF48. These genes were mainly enriched in 10 significantly enriched pathways, such as cell adhesion junctions, among which the differentially methylated gene GAL-8 was involved in inflammatory pathway signaling. For functional analysis of GAL-8, we first examined the differences in GAL-8 promoter methylation levels among different subgroups of human coronary tissue in the CON, CHD, and SCD groups using pyrophosphate sequencing. The results revealed reduced GAL-8 promoter methylation levels in the SCD group, while the difference between the CHD and CON groups was not statistically significant (P > 0.05). The reduced GAL-8 promoter methylation level was associated with upregulated GAL-8 expression, which led to increased expression of the inflammatory markers TNF-α, IL-1β, MCP-1, MIP-2, MMP-2, and MMP-9. This enhanced inflammatory response contributed to the accumulation of foam cells, thickening of the intima of human coronary arteries, and increased luminal stenosis, which promoted the occurrence of sudden coronary death. Next, we found that GAL-8 promoter methylation levels in PBMC were consistent with human coronary tissue. The unstable angina group (UAP) had significantly lower GAL-8 promoter methylation levels than stable angina (SAP) and healthy controls (CON) (P < 0.05), and there was a significant correlation between reduced GAL-8 promoter methylation levels and risk factors for coronary heart disease. These findings highlight the association between decreased GAL-8 promoter methylation and the presence of coronary heart disease risk factors. ROC curve analysis suggests that methylation of the GAL 8 promoter region is an independent risk factor for CHD. In conclusion, our study confirmed differential expression of GAL-8, LTF, MUC4D, TMEM9B, MYOM2, and ANK3 genes due to DNA methylation in the SCD group. We also established the consistency of GAL-8 promoter methylation alterations between human coronary tissue and patient peripheral blood monocytes. The decreased methylation level of the GAL-8 promoter may be related to the increased expression of GAL-8 and the coronary risk factors.

CONCLUSIONS

Accordingly, we hypothesized that reduced levels of GAL-8 promoter methylation may be an independent risk factor for adverse events in coronary heart disease.

Hypoxia preconditioning increases Notch1 activity by regulating DNA methylation in vitro and in vivo

BACKGROUND

Our previous research has demonstrated that hypoxic preconditioning (HPC) can improve spatial learning and memory abilities in adult mice. Adult hippocampal neurogenesis has been associated with learning and memory. The Neurogenic locus notch homolog protein (Notch) was involved in adult hippocampal neurogenesis, as well as in learning and memory. It is currently unclear whether the Notch pathway regulates hippocampal neuroregeneration by modifying the DNA methylation status of the Notch gene following HPC.

METHOD

The HPC animal model and cell model were established through repeated hypoxia exposure using mice and the mouse hippocampal neuronal cell line HT22. Step-down test was conducted on HPC mice. Real-time PCR and Western blot analysis were used to assess the mRNA and protein expression levels of Notch1 and hairy and enhancer of split1 (HES1). The presence of BrdU-positive cells and Notch1 expression in the hippocampal dental gyrus (DG) were examined with confocal microscopy. The methylation status of the Notch1 was analyzed using methylation-specific PCR (MS-PCR). HT22 cells were employed to elucidate the impact of HPC on Notch1 in vitro.

RESULTS

HPC significantly improved the step-down test performance of mice with elevated levels of mRNA and protein expression of Notch1 and HES1 (P < 0.05). The intensities of the Notch1 signal in the control group, the H group and the HPC group were 2.62 ± 0.57 × 107, 2.87 ± 0.84 × 107, and 3.32 ± 0.14 × 107, respectively, and the number of BrdU (+) cells in the hippocampal DG were 1.83 ± 0.54, 3.71 ± 0.64, and 7.29 ± 0.68 respectively. Compared with that in C and H group, the intensity of the Notch1 signal and the number of BrdU (+) cells increased significantly in HPC group (P < 0.05). The methylation levels of the Notch1 promoter 0.82 ± 0.03, 0.65 ± 0.03, and 0.60 ± 0.02 in the C, H, and HPC groups, respectively. The methylation levels of Notch1 decreased significantly (P < 0.05). The effect of HPC on HT22 cells exhibited similarities to that observed in the hippocampus.

CONCLUSION

HPC may confer neuroprotection by activating the Notch1 signaling pathway and regulating its methylation level, resulting in the regeneration of hippocampal neurons.

CancerMHL: the database of integrating key DNA methylation, histone modifications and lncRNAs in cancer

The discovery of key epigenetic modifications in cancer is of great significance for the study of disease biomarkers. Through the mining of epigenetic modification data relevant to cancer, some researches on epigenetic modifications are accumulating. In order to make it easier to integrate the effects of key epigenetic modifications on the related cancers, we established CancerMHL (http://www.positionprediction.cn/), which provide key DNA methylation, histone modifications and lncRNAs as well as the effect of these key epigenetic modifications on gene expression in several cancers. To facilitate data retrieval, CancerMHL offers flexible query options and filters, allowing users to access specific key epigenetic modifications according to their own needs. In addition, based on the epigenetic modification data, three online prediction tools had been offered in CancerMHL for users. CancerMHL will be a useful resource platform for further exploring novel and potential biomarkers and therapeutic targets in cancer. Database URL: http://www.positionprediction.cn/.

Biallelic non-productive enhancer-promoter interactions precede imprinted expression of Kcnk9 during mouse neural commitment

It is only partially understood how constitutive allelic methylation at imprinting control regions (ICRs) interacts with other regulation levels to drive timely parental allele-specific expression along large imprinted domains. The Peg13-Kcnk9 domain is an imprinted domain with important brain functions. To gain insights into its regulation during neural commitment, we performed an integrative analysis of its allele-specific epigenetic, transcriptomic, and cis-spatial organization using a mouse stem cell-based corticogenesis model that recapitulates the control of imprinted gene expression during neurodevelopment. We found that, despite an allelic higher-order chromatin structure associated with the paternally CTCF-bound Peg13 ICR, enhancer-Kcnk9 promoter contacts occurred on both alleles, although they were productive only on the maternal allele. This observation challenges the canonical model in which CTCF binding isolates the enhancer and its target gene on either side and suggests a more nuanced role for allelic CTCF binding at some ICRs.

Sex differences in DNA methylation across gestation: a large scale, cross-cohort, multi-tissue analysis

Biological sex is a key variable influencing many physiological systems. Disease prevalence as well as treatment success can be modified by sex. Differences emerge already early in life and include pregnancy complications and adverse birth outcomes. The placenta is a critical organ for fetal development and shows sex-based differences in the expression of hormones and cytokines. Epigenetic regulation, such as DNA methylation (DNAm), may underlie the previously reported placental sexual dimorphism. We associated placental DNAm with fetal sex in three cohorts. Individual cohort results were meta-analyzed with random-effects modelling. CpG-sites differentially methylated with sex were further investigated regarding pathway enrichment, overlap with methylation quantitative trait loci (meQTLs), and hits from phenome-wide association studies (PheWAS). We evaluated the consistency of findings across tissues (CVS, i.e. chorionic villus sampling from early placenta, and cord blood) as well as with gene expression. We identified 10,320 epigenome-wide significant sex-differentially methylated probes (DMPs) spread throughout the epigenome of the placenta at birth. Most DMPs presented with lower DNAm levels in females. DMPs mapped to genes upregulated in brain, were enriched for neurodevelopmental pathways and significantly overlapped with meQTLs and PheWAS hits. Effect sizes were moderately correlated between CVS and placenta at birth, but only weakly correlated between birth placenta and cord blood. Sex differential gene expression in birth placenta was less pronounced and implicated genetic regions only marginally overlapped with those associated with differential DNAm. Our study provides an integrative perspective on sex-differential DNAm in perinatal tissues underscoring the possible link between placenta and brain.

Structure-guided functional suppression of AML-associated DNMT3A hotspot mutations

DNA methyltransferases DNMT3A- and DNMT3B-mediated DNA methylation critically regulate epigenomic and transcriptomic patterning during development. The hotspot DNMT3A mutations at the site of Arg822 (R882) promote polymerization, leading to aberrant DNA methylation that may contribute to the pathogenesis of acute myeloid leukemia (AML). However, the molecular basis underlying the mutation-induced functional misregulation of DNMT3A remains unclear. Here, we report the crystal structures of the DNMT3A methyltransferase domain, revealing a molecular basis for its oligomerization behavior distinct to DNMT3B, and the enhanced intermolecular contacts caused by the R882H or R882C mutation. Our biochemical, cellular, and genomic DNA methylation analyses demonstrate that introducing the DNMT3B-converting mutations inhibits the R882H-/R882C-triggered DNMT3A polymerization and enhances substrate access, thereby eliminating the dominant-negative effect of the DNMT3A R882 mutations in cells. Together, this study provides mechanistic insights into DNMT3A R882 mutations-triggered aberrant oligomerization and DNA hypomethylation in AML, with important implications in cancer therapy.

Nonlinear DNA methylation trajectories in aging male mice

Although DNA methylation data yields highly accurate age predictors, little is known about the dynamics of this quintessential epigenomic biomarker during lifespan. To narrow the gap, we investigate the methylation trajectories of male mouse colon at five different time points of aging. Our study indicates the existence of sudden hypermethylation events at specific stages of life. Precisely, we identify two epigenomic switches during early-to-midlife (3-9 months) and mid-to-late-life (15-24 months) transitions, separating the rodents' life into three stages. These nonlinear methylation dynamics predominantly affect genes associated with the nervous system and enrich in bivalently marked chromatin regions. Based on groups of nonlinearly modified loci, we construct a clock-like classifier STageR (STage of aging estimatoR) that accurately predicts murine epigenetic stage. We demonstrate the universality of our clock in an independent mouse cohort and with publicly available datasets.

Investigating the potential of single-cell DNA methylation data to detect allele-specific methylation and imprinting

Allele-specific methylation (ASM) is an epigenetic modification whereby one parental allele becomes methylated and the other unmethylated at a specific locus. ASM is most often driven by the presence of nearby heterozygous variants that influence methylation, but also occurs somatically in the context of genomic imprinting. In this study, we investigate ASM using publicly available single-cell reduced representation bisulfite sequencing (scRRBS) data on 608 B cells sampled from six healthy B cell samples and 1,230 cells from 11 chronic lymphocytic leukemia (CLL) samples. We developed a likelihood-based criterion to test whether a CpG exhibited ASM, based on the distributions of methylated and unmethylated reads both within and across cells. Applying our likelihood ratio test, 65,998 CpG sites exhibited ASM in healthy B cell samples according to a Bonferroni criterion (p < 8.4 × 10-9), and 32,862 CpG sites exhibited ASM in CLL samples (p < 8.5 × 10-9). We also called ASM at the sample level. To evaluate the accuracy of our method, we called heterozygous variants from the scRRBS data, which enabled variant-based calls of ASM within each cell. Comparing sample-level ASM calls to the variant-based measures of ASM, we observed a positive predictive value of 76%-100% across samples. We observed high concordance of ASM across samples and an overrepresentation of ASM in previously reported imprinted genes and genes with imprinting binding motifs. Our study demonstrates that single-cell bisulfite sequencing is a potentially powerful tool to investigate ASM, especially as studies expand to increase the number of samples and cells sequenced.

Clinical performance and utility of a noninvasive urine-based methylation biomarker: TWIST1/Vimentin to detect urothelial carcinoma of the bladder

Traditional clinical modalities for diagnosing bladder urothelial carcinoma (BUC) remain limited due to their invasive nature, significant costs, discomfort associated with cystoscopy, and low sensitivity to urine cytology. Therefore, there is an urgent need to identify highly sensitive, specific, and noninvasive biomarkers for the early detection of this neoplasm. Hypermethylated TWIST1/Vimentin promoter may be a noninvasive biomarker using urine sample. We assessed the TWIST1/Vimentin promoter methylation status in urine samples using the Methylated Human TWIST1 and Vimentin Gene Detection Kit (Jiangsu MicroDiag Biomedicine Co., Ltd., China). The samples were collected from five groups: group 1 consisted of patients with BUC, group 2 contained other patients with urologic tumors, group 3 consisted of patients with benign diseases (e.g., urinary tract infections, lithiasis, and benign prostatic hyperplasia), Group 4 included UTUC (upper tract urothelial carcinoma) patients and group5 comprised healthy individuals. The study encompassed 77 BUC patients, and we evaluated the degree of methylation of the TWIST1/Vimentin gene in their urine samples. Notably, TWIST1/Vimentin positivity was significantly elevated in comparison to groups 2, 3 and 5 (all p < 0.001) at a rate of 77.9%, but no significant difference was observed when compared to group 4. In the relationship between TWIST1/Vimentin methylation and clinicopathological features of BC patients from our center, we found there was no significant association between TWIST1/Vimentin status and proteinuria and/or hematuria, and hypermethylation of TWIST1 / VIM genes was found in both high and low tumor grade and in both non-muscle invasive bladder cancer (stages Tis, Ta, or T1) and muscle-invasive bladder cancer (stage T2 or above). In the multivariable analysis for cancer detection, a positive TWIST1/Vimentin methylation were significantly linked to a heightened risk of BC. Moreover, TWIST1/Vimentin promoter methylation demonstrated an ability to detect BUC in urine samples with a sensitivity of 78% and a specificity of 83%. Our findings reveal that hypermethylation of the TWIST1/Vimentin promoter occurs in bladder urothelial carcinoma, and its high sensitivity and specificity suggest its potential as a screening and therapeutic biomarker for urothelial carcinoma of the bladder.

The association of cigarette smoking with DNA methylation and gene expression in human tissue samples

Cigarette smoking adversely affects many aspects of human health, and epigenetic responses to smoking may reflect mechanisms that mediate or defend against these effects. Prior studies of smoking and DNA methylation (DNAm), typically measured in leukocytes, have identified numerous smoking-associated regions (e.g., AHRR). To identify smoking-associated DNAm features in typically inaccessible tissues, we generated array-based DNAm data for 916 tissue samples from the GTEx (Genotype-Tissue Expression) project representing 9 tissue types (lung, colon, ovary, prostate, blood, breast, testis, kidney, and muscle). We identified 6,350 smoking-associated CpGs in lung tissue (n = 212) and 2,735 in colon tissue (n = 210), most not reported previously. For all 7 other tissue types (sample sizes 38-153), no clear associations were observed (false discovery rate 0.05), but some tissues showed enrichment for smoking-associated CpGs reported previously. For 1,646 loci (in lung) and 22 (in colon), smoking was associated with both DNAm and local gene expression. For loci detected in both lung and colon (e.g., AHRR, CYP1B1, CYP1A1), top CpGs often differed between tissues, but similar clusters of hyper- or hypomethylated CpGs were observed, with hypomethylation at regulatory elements corresponding to increased expression. For lung tissue, 17 hallmark gene sets were enriched for smoking-associated CpGs, including xenobiotic- and cancer-related gene sets. At least four smoking-associated regions in lung were impacted by lung methylation quantitative trait loci (QTLs) that co-localize with genome-wide association study (GWAS) signals for lung function (FEV1/FVC), suggesting epigenetic alterations can mediate the effects of smoking on lung health. Our multi-tissue approach has identified smoking-associated regions in disease-relevant tissues, including effects that are shared across tissue types.

Specific isoforms of the ubiquitin ligase gene WWP2 are targets of osteoarthritis genetic risk via a differentially methylated DNA sequence

BACKGROUND

Transitioning from a genetic association signal to an effector gene and a targetable molecular mechanism requires the application of functional fine-mapping tools such as reporter assays and genome editing. In this report, we undertook such studies on the osteoarthritis (OA) risk that is marked by single nucleotide polymorphism (SNP) rs34195470 (A > G). The OA risk-conferring G allele of this SNP associates with increased DNA methylation (DNAm) at two CpG dinucleotides within WWP2. This gene encodes a ubiquitin ligase and is the host gene of microRNA-140 (miR-140). WWP2 and miR-140 are both regulators of TGFβ signaling.

METHODS

Nucleic acids were extracted from adult OA (arthroplasty) and foetal cartilage. Samples were genotyped and DNAm quantified by pyrosequencing at the two CpGs plus 14 flanking CpGs. CpGs were tested for transcriptional regulatory effects using a chondrocyte cell line and reporter gene assay. DNAm was altered using epigenetic editing, with the impact on gene expression determined using RT-qPCR. In silico analysis complemented laboratory experiments.

RESULTS

rs34195470 genotype associates with differential methylation at 14 of the 16 CpGs in OA cartilage, forming a methylation quantitative trait locus (mQTL). The mQTL is less pronounced in foetal cartilage (5/16 CpGs). The reporter assay revealed that the CpGs reside within a transcriptional regulator. Epigenetic editing to increase their DNAm resulted in altered expression of the full-length and N-terminal transcript isoforms of WWP2. No changes in expression were observed for the C-terminal isoform of WWP2 or for miR-140.

CONCLUSIONS

As far as we are aware, this is the first experimental demonstration of an OA association signal targeting specific transcript isoforms of a gene. The WWP2 isoforms encode proteins with varying substrate specificities for the components of the TGFβ signaling pathway. Future analysis should focus on the substrates regulated by the two WWP2 isoforms that are the targets of this genetic risk.

Clinical significance of RNA methylation in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a primary liver malignancy with high mortality rates and poor prognosis. Recent advances in high-throughput sequencing and bioinformatic technologies have greatly enhanced the understanding of the genetic and epigenetic changes in liver cancer. Among these changes, RNA methylation, the most prevalent internal RNA modification, has emerged as a significant contributor of the development and progression of HCC. Growing evidence has reported significantly abnormal levels of RNA methylation and dysregulation of RNA-methylation-related enzymes in HCC tissues and cell lines. These alterations in RNA methylation play a crucial role in the regulation of various genes and signaling pathways involved in HCC, thereby promoting tumor progression. Understanding the pathogenesis of RNA methylation in HCC would help in developing prognostic biomarkers and targeted therapies for HCC. Targeting RNA-methylation-related molecules has shown promising potential in the management of HCC, in terms of developing novel prognostic biomarkers and therapies for HCC. Exploring the clinical application of targeted RNA methylation may provide new insights and approaches for the management of HCC. Further research in this field is warranted to fully understand the functional roles and underlying mechanisms of RNA methylation in HCC. In this review, we described the multifaceted functional roles and potential mechanisms of RNA methylation in HCC. Moreover, the prospects of clinical application of targeted RNA methylation for HCC management are discussed, which may provide the basis for subsequent in-depth research on RNA methylation in HCC.

Spatiotemporal DNA methylation dynamics shape megabase-scale methylome landscapes

DNA methylation is an essential epigenetic mechanism that regulates cellular reprogramming and development. Studies using whole-genome bisulfite sequencing have revealed distinct DNA methylome landscapes in human and mouse cells and tissues. However, the factors responsible for the differences in megabase-scale methylome patterns between cell types remain poorly understood. By analyzing publicly available 258 human and 301 mouse whole-genome bisulfite sequencing datasets, we reveal that genomic regions rich in guanine and cytosine, when located near the nuclear center, are highly susceptible to both global DNA demethylation and methylation events during embryonic and germline reprogramming. Furthermore, we found that regions that generate partially methylated domains during global DNA methylation are more likely to resist global DNA demethylation, contain high levels of adenine and thymine, and are adjacent to the nuclear lamina. The spatial properties of genomic regions, influenced by their guanine-cytosine content, are likely to affect the accessibility of molecules involved in DNA (de)methylation. These properties shape megabase-scale DNA methylation patterns and change as cells differentiate, leading to the emergence of different megabase-scale methylome patterns across cell types.

Genome-wide impact of cytosine methylation and DNA sequence context on UV-induced CPD formation

Exposure to ultraviolet (UV) light is the primary etiological agent for skin cancers because UV damages cellular DNA. The most frequent form of UV damage is the cyclobutane pyrimidine dimer (CPD), which consists of covalent linkages between neighboring pyrimidine bases in DNA. In human cells, the 5' position of cytosine bases in CG dinucleotides is frequently methylated, and methylated cytosines in the TP53 tumor suppressor are often sites of mutation hotspots in skin cancers. It has been argued that this is because cytosine methylation promotes UV-induced CPD formation; however, the effects of cytosine methylation on CPD formation are controversial, with conflicting results from previous studies. Here, we use a genome-wide method known as CPD-seq to map UVB- and UVC-induced CPDs across the yeast genome in the presence or absence in vitro methylation by the CpG methyltransferase M.SssI. Our data indicate that cytosine methylation increases UVB-induced CPD formation nearly 2-fold relative to unmethylated DNA, but the magnitude of induction depends on the flanking sequence context. Sequence contexts with a 5' guanine base (e.g., GCCG and GTCG) show the strongest induction due to cytosine methylation, potentially because these sequence contexts are less efficient at forming CPD lesions in the absence of methylation. We show that cytosine methylation also modulates UVC-induced CPD formation, albeit to a lesser extent than UVB. These findings can potentially reconcile previous studies, and define the impact of cytosine methylation on UV damage across a eukaryotic genome.

DNA methylation and chromatin accessibility predict age in the domestic dog

Across mammals, the epigenome is highly predictive of chronological age. These "epigenetic clocks," most of which have been built using DNA methylation (DNAm) profiles, have gained traction as biomarkers of aging and organismal health. While the ability of DNAm to predict chronological age has been repeatedly demonstrated, the ability of other epigenetic features to predict age remains unclear. Here, we use two types of epigenetic information-DNAm, and chromatin accessibility as measured by ATAC-seq-to develop age predictors in peripheral blood mononuclear cells sampled from a population of domesticated dogs. We measured DNAm and ATAC-seq profiles for 71 dogs, building separate predictive clocks from each, as well as the combined dataset. We also use fluorescence-assisted cell sorting to quantify major lymphoid populations for each sample. We found that chromatin accessibility can accurately predict chronological age (R2 ATAC = 26%), though less accurately than the DNAm clock (R2 DNAm = 33%), and the clock built from the combined datasets was comparable to both (R2 combined = 29%). We also observed various populations of CD62L+ T cells significantly correlated with dog age. Finally, we found that all three clocks selected features that were in or near at least two protein-coding genes: BAIAP2 and SCARF2, both previously implicated in processes related to cognitive or neurological impairment. Taken together, these results highlight the potential of chromatin accessibility as a complementary epigenetic resource for modeling and investigating biologic age.

DNMT3A Cooperates with YAP/TAZ to Drive Gallbladder Cancer Metastasis

Gallbladder cancer (GBC) is an extremely lethal malignancy with aggressive behaviors, including liver or distant metastasis; however, the underlying mechanisms driving the metastasis of GBC remain poorly understood. In this study, it is found that DNA methyltransferase DNMT3A is highly expressed in GBC tumor tissues compared to matched adjacent normal tissues. Clinicopathological analysis shows that DNMT3A is positively correlated with liver metastasis and poor overall survival outcomes in patients with GBC. Functional analysis confirms that DNMT3A promotes the metastasis of GBC cells in a manner dependent on its DNA methyltransferase activity. Mechanistically, DNMT3A interacts with and is recruited by YAP/TAZ to recognize and access the CpG island within the CDH1 promoter and generates hypermethylation of the CDH1 promoter, which leads to transcriptional silencing of CDH1 and accelerated epithelial-to-mesenchymal transition. Using tissue microarrays, the association between the expression of DNMT3A, YAP/TAZ, and CDH1 is confirmed, which affects the metastatic ability of GBC. These results reveal a novel mechanism through which DNMT3A recruitment by YAP/TAZ guides DNA methylation to drive GBC metastasis and provide insights into the treatment of GBC metastasis by targeting the functional connection between DNMT3A and YAP/TAZ.

Epigenetic age estimation of wild mice using faecal samples

Age is a key parameter in population ecology, with a myriad of biological processes changing with age as organisms develop in early life then later senesce. As age is often hard to accurately measure with non-lethal methods, epigenetic methods of age estimation (epigenetic clocks) have become a popular tool in animal ecology and are often developed or calibrated using captive animals of known age. However, studies typically rely on invasive blood or tissue samples, which limit their application in more sensitive or elusive species. Moreover, few studies have directly assessed how methylation patterns and epigenetic age estimates compare across environmental contexts (e.g. captive or laboratory-based vs. wild animals). Here, we built a targeted epigenetic clock from laboratory house mice (strain C57BL/6, Mus musculus) using DNA from non-invasive faecal samples, and then used it to estimate age in a population of wild mice (Mus musculus domesticus) of unknown age. This laboratory mouse-derived epigenetic clock accurately predicted adult wild mice to be older than juveniles and showed that wild mice typically increased in epigenetic age over time, but with wide variation in epigenetic ageing rate among individuals. Our results also suggested that, for a given body mass, wild mice had higher methylation across targeted CpG sites than laboratory mice (and consistently higher epigenetic age estimates as a result), even among the smallest, juvenile mice. This suggests wild and laboratory mice may display different CpG methylation levels from very early in life and indicates caution is needed when developing epigenetic clocks on laboratory animals and applying them in the wild.

Prognostic value of genome-wide methylation in acute-on-chronic hepatitis B liver failure

AIM

Methylation status of genome varies between pre-acute-on-chronic hepatitis B liver failure (pre-ACHBLF), acute-on-chronic hepatitis B liver failure (ACHBLF), and chronic hepatitis B patients. This study aimed to find better prognostic indicators for acute-on-chronic liver failure.

METHODS

The level of global genome methylation in peripheral blood mononuclear cells (PBMCs) was detected. The overall genome methylation rate was determined using MethylFlash™ Methylated DNA Quantification Kit(Colorimetric). DNMT activity were measured using DNA Methyltransferase Activity/Inhibition Assay Kit. Gene expression of DNA methyltransferases (DNMT)，methyl-CpG-binding domain (MBD) were detected by qRT-PCR.

RESULTS

The global genome methylation level in ACHBLF group was significantly higher than that in chronic hepatitis B group (P<0.001). There was also obvious difference of the global genome methylation level between pre-ACHBLF group and CHB group (P<0.001). Meanwhile, the activity of DNMT in ACHBLF group was significantly higher than that in chronic hepatitis B group (P<0.001). The mRNA expression level of DNMT1 was higher than that in pre-ACHBLF group (P<0.01) and CHB group (PP<0.001). The mRNA expression level of MBD1 in ACHBLF group was also higher than that in CHB group (P<0.001) and healthy controls (HCs) (P<0.01). And the mRNA expression level of MBD3 and MBD4 in ACHBLF, pre-ACHBLF and CHB group were lower than that in HCs (P<0.001). Meanwhile we observed an opposite change in the mRNA expression level of MECP2. The ROC curve suggested that global genome methylation level was a better prognostic predictor than MELD score in ACHBLF (AUC 0.950, SE 0.0237, 95%CI 0.874-0.986 VS AUC 0.863, SE 0.0439, 95%CI 0.765-0.931, P=0.0429).

CONCLUSIONS

Genome methylation level can be a good biomarker in predicting the severity and prognosis of ACHBLF.

Revealing genomic heterogeneity and commonality: A penalized integrative analysis approach accounting for the adjacency structure of measurements

Advancements in high-throughput genomic technologies have revolutionized the field of disease biomarker identification by providing large-scale genomic data. There is an increasing focus on understanding the relationships among diverse patient groups with distinct disease subtypes and characteristics. Complex diseases exhibit both heterogeneity and shared genomic factors, making it essential to investigate these patterns to accurately detect markers and comprehensively understand the diseases. Integrative analysis has emerged as a promising approach to address this challenge. However, existing studies have been limited by ignoring the adjacency structure of genomic measurements, such as single nucleotide polymorphisms (SNPs) and DNA methylations. In this study, we propose a structured integrative analysis method that incorporates a spline type penalty to accommodate this adjacency structure. We utilize a fused lasso type penalty to identify both heterogeneity and commonality across the groups. Extensive simulations demonstrate its superiority compared to several direct competing methods. The analysis of The Cancer Genome Atlas melanoma data with DNA methylation measurements and GENEVA diabetes data with SNP measurements exhibit that the proposed analysis lead to meaningful findings with better prediction performance and higher selection stability.

Methylation signatures as biomarkers for non-invasive early detection of breast cancer: A systematic review of the literature

BACKGROUND

Early detection of breast cancer would help alleviate the burden of treatment for early-stage breast cancer and help patient prognosis. There is currently no established gene panel that utilizes the potential of DNA methylation as a molecular signature for the early detection of breast cancer. This systematic review aims to identify the optimal methylation biomarkers for a non-invasive liquid biopsy assay and the gaps in knowledge regarding biomarkers for early detection of breast cancer.

METHODS

Following the PRISMA-ScR method, Pubmed and Google Scholar was searched for publications related to methylation biomarkers in breast cancer over a five-year period. Eligible publications were mined for key data fields such as study aims, cohort demographics, types of breast cancer studied, technologies used, and outcomes. Data was analyzed to address the objectives of the review.

RESULTS

Literature search identified 112 studies of which based on eligibility criteria, 13 studies were included. 28 potential methylation gene targets were identified, of which 23 were methylated at the promoter region, 1 was methylated in the body of the gene and 4 were methylated at yet to be identified locations.

CONCLUSIONS

Our evaluation shows that at minimum APC, RASSFI, and FOXA1 genes would be a promising set of genes to start with for the early detection of breast cancer, based on the sensitivity and specificity outlined in the studies. Prospective studies are needed to optimize biomarkers for broader impact in early detection of breast cancer.

MIR145 Core Promoter Methylation in Pretreatment Cell-Free DNA: A Liquid Biopsy Tool for Muscle-Invasive Bladder Cancer Treatment Outcome

PURPOSE

The lack of personalized management of bladder cancer (BlCa) results in patients' lifelong post-treatment monitoring with invasive interventions, underlying the urgent need for tailored and minimally invasive health care services. On the basis of our previous findings on miR-143/145 cluster methylation in bladder tumors, we evaluated its clinical significance in pretreatment cell-free DNA (cfDNA) of patients with BlCa.

MATERIALS AND METHODS

Methylation analysis was performed in our screening cohort (120 patients with BlCa; 20 age-matched healthy donors) by bisulfite-based pyrosequencing. Tumor recurrence/progression for patients with non-muscle-invasive bladder cancer, and progression and mortality for patients with muscle-invasive bladder cancer (MIBC) were used as clinical end point events in survival analysis. Bootstrap analysis was applied for internal validation of Cox regression models and decision curve analysis for assessment of clinical benefit on disease prognosis.

RESULTS

Decreased methylation of MIR145 core promoter in pretreatment cfDNA was associated with short-term disease progression (multivariate Cox: hazard ratio [HR], 2.027 [95% CI, 1.157 to 3.551]; P = .010) and poor overall survival (multivariate Cox: HR, 2.098 [95% CI, 1.154 to 3.817]; P = .009) of patients with MIBC after radical cystectomy (RC). Multivariate models incorporating MIR145 promoter methylation in cfDNA with tumor stage clearly ameliorated patients' risk stratification, highlighting superior clinical benefit in MIBC prognostication.

CONCLUSION

Reduced pretreatment cfDNA methylation of MIR145 core promoter was markedly correlated with increased risk for short-term progression and worse survival of patients with MIBC after RC and adjuvant therapy, supporting modern personalized and minimally invasive prognosis. Methylation profiling of MIR145 core promoter in pretreatment cfDNA could serve as a minimally invasive and independent predictor of MIBC treatment outcome and emerge as a promising marker for blood-based test in BlCa.

Epigenome-wide association study of DNA methylation in maternal blood leukocytes with BMI in pregnancy and gestational weight gain

OBJECTIVES

We aimed to discover CpG sites with differential DNA methylation in peripheral blood leukocytes associated with body mass index (BMI) in pregnancy and gestational weight gain (GWG) in women of European and South Asian ancestry. Furthermore, we aimed to investigate how the identified sites were associated with methylation quantitative trait loci, gene ontology, and cardiometabolic parameters.

METHODS

In the Epigenetics in pregnancy (EPIPREG) sample we quantified maternal DNA methylation in peripheral blood leukocytes in gestational week 28 with Illumina's MethylationEPIC BeadChip. In women with European (n = 303) and South Asian (n = 164) ancestry, we performed an epigenome-wide association study of BMI in gestational week 28 and GWG between gestational weeks 15 and 28 using a meta-analysis approach. Replication was performed in the Norwegian Mother, Father, and Child Cohort Study, the Study of Assisted Reproductive Technologies (MoBa-START) (n = 877, mainly European/Norwegian).

RESULTS

We identified one CpG site significantly associated with GWG (p 5.8 × 10-8) and five CpG sites associated with BMI at gestational week 28 (p from 4.0 × 10-8 to 2.1 × 10-10). Of these, we were able to replicate three in MoBa-START; cg02786370, cg19758958 and cg10472537. Two sites are located in genes previously associated with blood pressure and BMI. DNA methylation at the three replicated CpG sites were associated with levels of blood pressure, lipids and glucose in EPIPREG (p from 1.2 × 10-8 to 0.04).

CONCLUSIONS

We identified five CpG sites associated with BMI at gestational week 28, and one with GWG. Three of the sites were replicated in an independent cohort. Several genetic variants were associated with DNA methylation at cg02786379 and cg16733643 suggesting a genetic component influencing differential methylation. The identified CpG sites were associated with cardiometabolic traits.

CLINICALTRIALS

GOV REGISTRATION NO

Not applicable.

Physio-biochemical and DNA methylation analysis of the defense response network of wheat to drought stress

In the present work, physio-biochemical and DNA methylation analysis were conducted in wheat (Triticum aestivum L.) cultivars "Bolani" (drought-tolerant) and "Sistan" (drought-sensitive) during drought treatments: well-watered (at 90% field capacity (FC)), mild stress (at 50% FC, and severe stress (at 25% FC). During severe stress, O2•- and H2O2 content in cultivar Sistan showed significant increase (by 1.3 and 2.5-fold, respectively) relative to cultivar Bolani. In Bolani, the increased levels of radical scavenging activity (by 32%), glycine betaine (GB) (by 11.44%), proline (4-fold), abscisic acid (by 63.76%), and more stability of relative water content (RWC) (2-fold) were observed against drought-induced oxidative stress. Methylation level significantly decreased from 70.26% to 60.64% in Bolani and from 69.06% to 59.85% in Sistan during stress, and higher decreased tendency was related to CG and CHG in Bolani but CG in Sistan under severe stress. Methylation patterns showed that the highest polymorphism in Bolani was mainly as CG. As the intensity of stress increased, the enhanced physio-biochemical responses of Bolani cultivar were accompanied by a more decrease in the number of unchanged bands. According to heat map analysis, the highest difference (84.38%) in methylation patterns was observed between control and severe stress. Multivariate analysis using principal component analysis (PCA) showed a cultivar-specific methylation during stress and that methylation changes between cultivars are much higher than that of within a cultivar. Higher methylation to demethylation in Bolani (30.06 vs. 22.12%) compared to that of cultivar Sistan (23.21 vs. 30.15%) indicated more demethylation did not induce tolerance responses in Sistan. Sequencing differentially methylated fragments along with qRT-PCR analysis showed the efficient role of various DNA fragments, including demethylated fragments such as phosphoenol pyruvate carboxylase (PEPC), beta-glucosidase (BGlu), glycosyltransferase (GT), glutathione S-transferase (GST) and lysine demethylase (LSD) genes and methylated fragments like ubiquitin E2 enzyme genes in the development of drought tolerance. These results suggested the specific roles of DNA methylation in development of drought tolerance in wheat landrace.

A preliminary investigation of epigenome-wide DNA methylation and temperament during infancy

This study provides preliminary evidence for an epigenetic architecture of infant temperament. At 12 months of age, blood was collected and assayed for DNA methylation and maternally reported infant temperament was assessed using the Infant Behavior Questionnaire in 67 mother-infant dyads. Epigenome-wide analyses showed that the higher order temperament dimensions Surgency and Negative Affect were associated with DNA methylation. The epigenetic signatures of Surgency and Negative Affect were situated at genes involved in synaptic signaling and plasticity. Although replication is required, these results are consistent with a biologically based model of temperament, create new avenues for hypothesis-driven research into epigenetic pathways that underlie individual differences in temperament, and demonstrate that infant temperament has a widespread epigenetic signature in the methylome.

Reshaped DNA methylation cooperating with homoeolog-divergent expression promotes improved root traits in synthesized tetraploid wheat

Polyploidization is a major event driving plant evolution and domestication. However, how reshaped epigenetic modifications coordinate gene transcription to generate phenotypic variations during wheat polyploidization is currently elusive. Here, we profiled transcriptomes and DNA methylomes of two diploid wheat accessions (SlSl and AA) and their synthetic allotetraploid wheat line (SlSlAA), which displayed elongated root hair and improved root capability for nitrate uptake and assimilation after tetraploidization. Globally decreased DNA methylation levels with a reduced difference between subgenomes were observed in the roots of SlSlAA. DNA methylation changes in first exon showed strong connections with altered transcription during tetraploidization. Homoeolog-specific transcription was associated with biased DNA methylation as shaped by homoeologous sequence variation. The hypomethylated promoters showed significantly enriched binding sites for MYB, which may affect gene transcription in response to root hair growth. Two master regulators in root hair elongation pathway, AlCPC and TuRSL4, exhibited upregulated transcription levels accompanied by hypomethylation in promoter, which may contribute to the elongated root hair. The upregulated nitrate transporter genes, including NPFs and NRTs, also are significantly associated with hypomethylation, indicating an epigenetic-incorporated regulation manner in improving nitrogen use efficiency. Collectively, these results provided new insights into epigenetic changes in response to crop polyploidization and underscored the importance of epigenetic regulation in improving crop traits.

Epigenetic and transcriptional landscapes during cerebral cortex development in a microcephaly mouse model

The cerebral cortex is a pivotal structure integral to advanced brain functions within the mammalian central nervous system. DNA methylation and hydroxymethylation play important roles in regulating cerebral cortex development. However, it remains unclear whether abnormal cerebral cortex development, such as microcephaly, could rescale the epigenetic landscape, potentially contributing to dysregulated gene expression during brain development. In this study, we characterize and compare the DNA methylome/hydroxymethylome and transcriptome profiles of the cerebral cortex across several developmental stages in wild-type (WT) mice and Mcph1 knockout (Mcph1-del) mice with severe microcephaly. Intriguingly, we discover a global reduction of 5'-hydroxymethylcytosine (5hmC) level, primarily in TET1-binding regions, in Mcph1-del mice compared to WT mice during juvenile and adult stages. Notably, genes exhibiting diminished 5hmC levels and concurrently decreased expression are essential for neurodevelopment and brain functions. Additionally, genes displaying a delayed accumulation of 5hmC in Mcph1-del mice are significantly associated with the establishment and maintenance of the nervous system during the adult stage. These findings reveal that aberrant cerebral cortex development in the early stages profoundly alters the epigenetic regulation program, which provides unique insights into the molecular mechanisms underpinning diseases related to cerebral cortex development.

Mapping parental DMRs predictive of local and distal methylome remodeling in epigenetic F1 hybrids

F1 hybrids derived from a cross between two inbred parental lines often display widespread changes in DNA methylation and gene expression patterns relative to their parents. An emerging challenge is to understand how parental epigenomic differences contribute to these events. Here, we generated a large mapping panel of F1 epigenetic hybrids, whose parents are isogenic but variable in their DNA methylation patterns. Using a combination of multi-omic profiling and epigenetic mapping strategies we show that differentially methylated regions in parental pericentromeres act as major reorganizers of hybrid methylomes and transcriptomes, even in the absence of genetic variation. These parental differentially methylated regions are associated with hybrid methylation remodeling events at thousands of target regions throughout the genome, both locally (in cis) and distally (in trans). Many of these distally-induced methylation changes lead to nonadditive expression of nearby genes and associate with phenotypic heterosis. Our study highlights the pleiotropic potential of parental pericentromeres in the functional remodeling of hybrid genomes and phenotypes.

Genome-wide identification, evolution of DNA methyltransferases and their expression under salinity stress in Larimichthys crocea

DNA methyltransferases (Dnmts) are responsible for DNA methylation which influences patterns of gene expression and plays a crucial role in response to environmental changes. In this study, 7 LcDnmt genes were identified in the genome of large yellow croaker (Larimichthys crocea). The comprehensive analysis was conducted on gene structure, protein and location site of LcDnmts. LcDnmt proteins belonged to three groups (Dnmt1, Dnmt2, and Dnmt3) according to their conserved domains and phylogenetic analysis. Although Dnmt3 can be further divided into three sub groups (Dnmt3a, Dnmt3b, and Dnmt3l), there is no Dnmnt3l member in the large yellow croaker. Phylogenetic analysis revealed that the Dnmt family was highly conserved in teleosts. Expression patterns derived from the RNA-seq, qRT-PCR and Western blot analysis revealed that 2 LcDnmt genes (LcDnmt1 and LcDnmt3a2) significantly regulated under salinity stress in the liver, which was found to be dominantly expressed in the intestine and brain, respectively. These two genes may play an important role in the salinity stress of large yellow croaker and represent candidates for future functional analysis. Our results revealed the conservation of Dnmts during evolution and indicated a potential role of Dnmts in epigenetic regulation of response to salinity stress.

DNMT1 methylation of LncRNA-ANRIL causes myocardial fibrosis pyroptosis by interfering with the NLRP3/Caspase-1 pathway

Myocardial fibrosis is a common pathological manifestation that occurs in various cardiac diseases. The present investigation aims to reveal how DNMT1/lncRNA-ANRIL/NLRP3 influences fibrosis and cardiac fibroblast pyroptosis. Here, we used ISO to induce myocardial fibrosis in mice, and LPS and ATP to induce myocardial fibroblast pyroptosis. The results showed that DNMT1, Caspase-1, and NLRP3 expression were significantly increased in fibrotic murine myocardium and pyroptotic cardiac fibroblasts, whereas LncRNA-ANRIL expression was decreased. DNMT1 overexpression decreased the level of LncRNA-ANRIL while increasing the levels of NLRP3 and Caspase-1. Contrarily, silencing DNMT1 increased the LncRNA-ANRIL and decreased the levels of NLRP3 and Caspase-1. Silencing LncRNA-ANRIL increased the levels of NLRP3 and Caspase-1. The present findings suggest that DNMT1 can methylate LncRNA-ANRIL during the development of myocardial fibrosis and CFs cell scorching, resulting in low LncRNA-ANRIL expression, thereby influencing myocardial fibrosis and cardiac fibroblast pyroptosis.

FinaleMe: Predicting DNA methylation by the fragmentation patterns of plasma cell-free DNA

Analysis of DNA methylation in cell-free DNA reveals clinically relevant biomarkers but requires specialized protocols such as whole-genome bisulfite sequencing. Meanwhile, millions of cell-free DNA samples are being profiled by whole-genome sequencing. Here, we develop FinaleMe, a non-homogeneous Hidden Markov Model, to predict DNA methylation of cell-free DNA and, therefore, tissues-of-origin, directly from plasma whole-genome sequencing. We validate the performance with 80 pairs of deep and shallow-coverage whole-genome sequencing and whole-genome bisulfite sequencing data.

Mating system is associated with seed phenotypes upon loss of RNA-directed DNA methylation in Brassicaceae

In plants, de novo DNA methylation is guided by 24-nt short interfering (si)RNAs in a process called RNA-directed DNA methylation (RdDM). Primarily targeted at transposons, RdDM causes transcriptional silencing and can indirectly influence expression of neighboring genes. During reproduction, a small number of siRNA loci are dramatically upregulated in the maternally derived seed coat, suggesting that RdDM might have a special function during reproduction. However, the developmental consequence of RdDM has been difficult to dissect because disruption of RdDM does not result in overt phenotypes in Arabidopsis (Arabidopsis thaliana), where the pathway has been most thoroughly studied. In contrast, Brassica rapa mutants lacking RdDM have a severe seed production defect, which is determined by the maternal sporophytic genotype. To explore the factors that underlie the different phenotypes of these species, we produced RdDM mutations in 3 additional members of the Brassicaceae family: Camelina sativa, Capsella rubella, and Capsella grandiflora. Among these 3 species, only mutations in the obligate outcrosser, C. grandiflora, displayed a seed production defect similar to Brassica rapa mutants, suggesting that mating system is a key determinant for reproductive phenotypes in RdDM mutants.

Differential DNA methylation landscape of miRNAs genes in mice liver fibrosis

BACKGROUND

Patients with chronic liver disease were found nearly all to have liver fibrosis, which is characterized by excess accumulation of extracellular matrix (ECM) proteins. While ECM accumulation can prevent liver infection and injury, it can destroy normal liver function and architecture. miRNA's own regulation was involved in DNA methylation change. The purpose of this study is to detect DNA methylation landscape of miRNAs genes in mice liver fibrosis tissues.

METHODS

Male mice (10-12 weeks) were injected CCl4 from abdominal cavity to induced liver fibrosis. 850 K BeadChips were used to examine DNA methylation change in whole genome. The methylation change of 16 CpG dinucleotides located in promoter regions of 4 miRNA genes were detected by bisulfite sequencing polymerase chain reaction (BSP) to verify chip data accuracy, and these 4 miRNA genes' expressions were detected by RT-qPCR methods.

RESULTS

There are 769 differential methylation sites (DMS) in total between fibrotic liver tissue and normal mice liver tissue, which were related with 148 different miRNA genes. Chips array data were confirmed by bisulfite sequencing polymerase chain reaction (R = 0.953; P < 0.01). GO analysis of the target genes of 2 miRNA revealed that protein binding, cytoplasm and chromatin binding activity were commonly enriched; KEGG pathway enrichment analysis displayed that TGF-beta signaling pathway was commonly enriched.

CONCLUSION

The DNA of 148 miRNA genes was found to have methylation change in liver fibrosis tissue. These discoveries in miRNA genes are beneficial to future miRNA function research in liver fibrosis.

Population epigenetics: DNA methylation in the plant omics era

DNA methylation plays an important role in many biological processes. The mechanisms underlying the establishment and maintenance of DNA methylation are well understood thanks to decades of research using DNA methylation mutants, primarily in Arabidopsis (Arabidopsis thaliana) accession Col-0. Recent genome-wide association studies (GWASs) using the methylomes of natural accessions have uncovered a complex and distinct genetic basis of variation in DNA methylation at the population level. Sequencing following bisulfite treatment has served as an excellent method for quantifying DNA methylation. Unlike studies focusing on specific accessions with reference genomes, population-scale methylome research often requires an additional round of sequencing beyond obtaining genome assemblies or genetic variations from whole-genome sequencing data, which can be cost prohibitive. Here, we provide an overview of recently developed bisulfite-free methods for quantifying methylation and cost-effective approaches for the simultaneous detection of genetic and epigenetic information. We also discuss the plasticity of DNA methylation in a specific Arabidopsis accession, the contribution of DNA methylation to plant adaptation, and the genetic determinants of variation in DNA methylation in natural populations. The recently developed technology and knowledge will greatly benefit future studies in population epigenomes.

Transcription factor PpNAC1 and DNA demethylase PpDML1 synergistically regulate peach fruit ripening

Fruit ripening is accompanied by dramatic changes in color, texture, and flavor and is regulated by transcription factors (TFs) and epigenetic factors. However, the detailed regulatory mechanism remains unclear. Gene expression patterns suggest that PpNAC1 (NAM/ATAF1/2/CUC) TF plays a major role in peach (Prunus persica) fruit ripening. DNA affinity purification (DAP)-seq combined with transactivation tests demonstrated that PpNAC1 can directly activate the expression of multiple ripening-related genes, including ACC synthase1 (PpACS1) and ACC oxidase1 (PpACO1) involved in ethylene biosynthesis, pectinesterase1 (PpPME1), pectate lyase1 (PpPL1), and polygalacturonase1 (PpPG1) related to cell wall modification, and lipase1 (PpLIP1), fatty acid desaturase (PpFAD3-1), and alcohol acyltransferase1 (PpAAT1) involved in volatiles synthesis. Overexpression of PpNAC1 in the tomato (Solanum lycopersicum) nor (nonripening) mutant restored fruit ripening, and its transient overexpression in peach fruit induced target gene expression, supporting a positive role of PpNAC1 in fruit ripening. The enhanced transcript levels of PpNAC1 and its target genes were associated with decreases in their promoter mCG methylation during ripening. Declining DNA methylation was negatively associated with increased transcripts of DNA demethylase1 (PpDML1), whose promoter is recognized and activated by PpNAC1. We propose that decreased methylation of the promoter region of PpNAC1 leads to a subsequent decrease in DNA methylation levels and enhanced transcription of ripening-related genes. These results indicate that positive feedback between PpNAC1 and PpDML1 plays an important role in directly regulating expression of multiple genes required for peach ripening and quality formation.

Heritable changes of epialleles near genes in maize can be triggered in the absence of CHH methylation

Trans-chromosomal interactions resulting in changes in DNA methylation during hybridization have been observed in several plant species. However, little is known about the causes or consequences of these interactions. Here, we compared DNA methylomes of F1 hybrids that are mutant for a small RNA biogenesis gene, Mop1 (Mediator of paramutation1), with that of their parents, wild-type siblings, and backcrossed progeny in maize (Zea mays). Our data show that hybridization triggers global changes in both trans-chromosomal methylation (TCM) and trans-chromosomal demethylation (TCdM), most of which involved changes in CHH methylation. In more than 60% of these TCM differentially methylated regions (DMRs) in which small RNAs are available, no significant changes in the quantity of small RNAs were observed. Methylation at the CHH TCM DMRs was largely lost in the mop1 mutant, although the effects of this mutant varied depending on the location of these DMRs. Interestingly, an increase in CHH at TCM DMRs was associated with enhanced expression of a subset of highly expressed genes and suppressed expression of a small number of lowly expressed genes. Examination of the methylation levels in backcrossed plants demonstrates that both TCM and TCdM can be maintained in the subsequent generation, but that TCdM is more stable than TCM. Surprisingly, although increased CHH methylation in most TCM DMRs in F1 plants required Mop1, initiation of a new epigenetic state of these DMRs did not require a functional copy of this gene, suggesting that initiation of these changes is independent of RNA-directed DNA methylation.