Changes In Methylation Patterns Research Articles

Age Prediction Using DNA Methylation Heterogeneity Metrics.

Dynamic changes in genomic DNA methylation patterns govern the epigenetic developmental programs and accompany the organism's aging. Epigenetic clock (eAge) algorithms utilize DNA methylation to estimate the age and risk factors for diseases as well as analyze the impact of various interventions. High-throughput bisulfite sequencing methods, such as reduced-representation bisulfite sequencing (RRBS) or whole genome bisulfite sequencing (WGBS), provide an opportunity to identify the genomic regions of disordered or heterogeneous DNA methylation, which might be associated with cell-type heterogeneity, DNA methylation erosion, and allele-specific methylation. We systematically evaluated the applicability of five scores assessing the variability of methylation patterns by evaluating within-sample heterogeneity (WSH) to construct human blood epigenetic clock models using RRBS data. The best performance was demonstrated by the model based on a metric designed to assess DNA methylation erosion with an MAE of 3.686 years. We also trained a prediction model that uses the average methylation level over genomic regions. Although this region-based model was relatively more efficient than the WSH-based model, the latter required the analysis of just a few short genomic regions and, therefore, could be a useful tool to design a reduced epigenetic clock that is analyzed by targeted next-generation sequencing.

Abstract PO2-01-08: Differential HOXB13 gene expression and promoter methylation analysis in breast cancer

Abstract Background: The Breast Cancer Index (BCI) is a gene expression-based signature comprising two functional biomarker panels: the Molecular Grade Index (MGI) and BCI (H/I), which is a ratio of the HOXB13 and IL17BR gene expression. Several studies have shown that BCI (H/I) is a predictive biomarker for extended adjuvant endocrine therapy benefit in hormone receptor-positive (HR+) early-stage breast cancer. Molecular mechanisms underlying endocrine responsiveness remain to be fully explored. The objective of this analysis is to evaluate the correlation between gene expression and methylation in breast cancer patients displaying different HOXB13 mRNA expression levels from The Cancer Genome Atlas (TCGA) project. Methods: Data from methylation microarrays and mRNA sequencing were examined in combination with clinical metadata from 1,095 TCGA breast cancer patients. After removing outliers, HR+ samples were ordered based on their HOXB13 expression levels and the top 10% of samples (HOXB13-high; n=95) and bottom 10% (HOXB13-low; n=95) were selected for further analysis. Differentially expressed genes (DEGs) were determined by comparing all protein-coding genes between the HOXB13-high and HOXB13-low sets, based on an absolute log-fold change above 2 and a Benjamini-Hochberg adjusted p-value threshold of 0.01. Among the subset of samples with matching methylation data (n=60 for the HOXB13-high group and n=48 for the HOXB13-low group), hypo-methylated and hyper-methylated differentially methylated probes (DMPs) were identified based on at least 10% change of β (i.e., average promoter methylation) and a Benjamini-Hochberg adjusted p-value threshold of 0.01. Motif and transcription factor (TF) enrichment analyses were identified at a minimum incidence of 10 and a lower boundary of 1.5 for the 95% confidence interval of the odds ratio. Results: Our analysis identified a total of 613 DEGs between the HOXB13-high and HOXB13-low groups. Gene ontology analysis of DEGs revealed a statistically significant enrichment of genes associated with PTK6 regulated cell cycle, oncogene-induced cellular senescence, and regulation of T cell activation. Analysis of protein-protein interactions of differentially expressed genes revealed differences in key biological processes including changes in cell cycle regulation, p53 pathway, and IL-17 signaling. A total of 5,295 hyper-methylated and 580 hypo-methylated DMPs were discovered when comparing HOXB13-high and HOXB13-low samples. Changes in global methylation patterns enabled classification of breast cancer samples with high or low HOXB13 expression with an accuracy of 0.90. Reconstruction of gene regulatory networks from DNA methylation and transcriptome profiles elucidated significant pairs of DMPs and differentially expressed genes. Specifically, a total of 197 differentially expressed genes were attributed to hyper-methylated DMPs, including genes involved in response to estrogen, activation of HOX genes during differentiation, and drug-mediated inhibition of CDK4/6 activity. Additionally, 8 differentially expressed genes were attributed to hypo-methylated DMPs and were associated with proteasomal protein catabolic processes. Lastly, motif analysis of transcriptional factors for the hyper-methylated DMPs revealed enrichment of binding motifs attributed to FOXA1, ESR1, XBR1, and FOXP1. Conclusion: A comprehensive and comparative analysis of mRNA expression levels and methylation patterns between TCGA breast cancer samples with high and low expression of HOXB13 revealed key signaling pathways and biological processes that may provide insights on the molecular mechanism of HOXB13 in the regulation of response to endocrine therapy in HR+ breast cancer. Citation Format: Natalia Siuliukina, Yi Zhang, Kai Treuner, Mark Pegram. Differential HOXB13 gene expression and promoter methylation analysis in breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-01-08.

Placental DNA methylation signatures of prenatal air pollution exposure and potential effects on birth outcomes: an analysis of three prospective cohorts.

Pregnancy air pollution exposure (PAPE) has been linked to a wide range of adverse birth and childhood outcomes, but there is a paucity of data on its influence on the placental epigenome, which can regulate the programming of physiological functions and affect child development. This study aimed to investigate the association between prenatal air pollutant exposure concentrations and changes in placental DNA methylation patterns, and to explore the potential windows of susceptibility and sex-specific alterations. This multi-site study used three prospective population-based mother-child cohorts: EDEN, PELAGIE, and SEPAGES, originating from four French geographical regions (Nancy, Poitiers, Brittany, and Grenoble). Pregnant women were included between 2003 and 2006 for EDEN and PELAGIE, and between 2014 and 2017 for SEPAGES. The main eligibility criteria were: being older than 18 years, having a singleton pregnancy, and living and planning to deliver in one of the maternity clinics in one of the study areas. A total of 1539 mother-child pairs were analysed, measuring placental DNA methylation using Illumina BeadChips. We used validated spatiotemporally resolved models to estimate PM2·5, PM10, and NO2 exposure over each trimester of pregnancy at the maternal residential address. We conducted a pooled adjusted epigenome-wide association study to identify differentially methylated 5'-C-phosphate-G-3' (CpG) sites and regions (assessed using the Infinium HumanMethylationEPIC BeadChip array, n=871), including sex-specific and sex-linked alterations, and independently validated our results (assessed using the Infinium HumanMethylation450 BeadChip array, n=668). We identified four CpGs and 28 regions associated with PAPE in the total population, 469 CpGs and 87 regions in male infants, and 150 CpGs and 66 regions in female infants. We validated 35% of the CpGs available. More than 30% of the identified CpGs were related to one (or more) birth outcome and most significant alterations were enriched for neural development, immunity, and metabolism related genes. The 28 regions identified for both sexes overlapped with imprinted genes (four genes), and were associated with neurodevelopment (nine genes), immune system (seven genes), and metabolism (five genes). Most associations were observed for the third trimester for female infants (134 of 150 CpGs), and throughout pregnancy (281 of 469 CpGs) and the first trimester (237 of 469 CpGs) for male infants. These findings highlight the molecular pathways through which PAPE might affect child health in a widespread and sex-specific manner, identifying the genes involved in the major physiological functions of a developing child. Further studies are needed to elucidate whether these epigenetic changes persist and affect health later in life. French Agency for National Research, Fondation pour la Recherche Médicale, Fondation de France, and the Plan Cancer.

Ameliorative Effects of Paclobutrazol via Physio-Biochemical and Molecular Manifestation in Rice under Water Deficit Stress

We investigated the effects of an optimized dose (100 mg/kg) of paclobutrazol (PBZ) on various physio-biochemical and molecular parameters in three rice varieties (N22, IR64, and IR64 DTY1.1) under water deficit stress (WDS). Concurrently, a dose of 100 mg/kg of PBZ was applied through drenching. Samples were collected at both mild stress [75%‒80% relative water content (RWC)] and severe stress (60%‒65% RWC) conditions. Physio-biochemical parameters, including dry matter, RWC, membrane stability index (MSI), grain yield, total chlorophyll content, chlorophyll stability index, drought susceptibility index, drought tolerance efficiency, total antioxidant activity, abscisic acid (ABA) content, and gibberellic acid (GA) content, were measured. The results showed that PBZ treatment positively influenced the physio-biochemical parameters, significantly increasing dry matter (16.27%‒ 61.91%), RWC (6.48%‒16.34%), MSI (4.37%‒10.35%), and total chlorophyll content (8.97%‒29.09%) in the rice varieties under both mild and severe WDS. Moreover, PBZ treatment reduced drought susceptibility (0.83‒0.95) and enhanced drought tolerance efficiency (60.92%‒86.78%), indicating its potential as a stress-mitigating agent. This study also explored the molecular responses of the rice varieties to PBZ treatment under WDS. Global methylation analysis revealed changes in DNA methylation patterns, indicating the regulatory influence of PBZ on gene expression. The expression analysis of genes involved in the diversification of geranylgeranyl pyrophosphate towards the biosynthesis of ABA, GA, and chlorophyll showed alterations in their expression levels, suggesting the involvement of PBZ in the isoprenoid pathway. Overall, this study provides valuable insights into the potential mechanisms by which PBZ modulates physiological and molecular responses in rice plants under WDS. The findings highlight the importance of PBZ as a promising tool for enhancing drought tolerance in rice and offer valuable information for future research in crop stress management.

Changes in BDNF methylation patterns after cognitive remediation therapy in schizophrenia: A randomized and controlled trial

Although cognitive remediation therapy (CRT) produces cognitive benefits in schizophrenia, we do not yet understand whether molecular changes are associated with this cognitive improvement. A gene central to synaptic plasticity, the BDNF, has been proposed as one potential route. This study assesses whether BDNF methylation changes following CRT-produced cognitive improvement are detected. A randomized and controlled trial was performed with two groups (CRT, n = 40; TAU: Treatment as Usual, n = 20) on a sample of participants with schizophrenia. CRT was delivered by trained therapists using a web-based computerized program. Mixed Models, where the interaction of treatment (CRT, TAU) by time (T0: 0 weeks, T1: 16 weeks) was the main effect were used. Then, we tested the association between the treatment and methylation changes in three CpG islands of the BDNF gene. CRT group showed significant improvements in some cognitive domains. Between-groups differential changes in 5 CpG units over time were found, 4 in island 1 (CpG1.2, CpG1.7, CpG1.10, CpG1.17) and 1 in island 3 (CpG3.2). CRT group showed increases in methylation in CpG1.2, CpG1.7 and decreases in pG1.10, CpG1.17, and CpG3.2. Differences in the degree of methylation were associated with changes in Speed of Processing, Working Memory, and Verbal Learning within the CRT group. Those findings provide new data on the relationship between cognitive improvement and changes in peripheral methylation levels of BDNF gene, a key factor involved in neuroplasticity regulation.Trial Registration: NCT04278027.

Abstract 3: Multiomics analyses reveal functional DNA, methylation pattern changes in clinical transgenic T-cell receptor cell therapy products

Abstract Background: Transgenic T-cell receptor T-cells (TCR-T) directed against tumor-specific antigens are associated with robust initial clinical responses. However, these responses are often not durable, and patients relapse frequently. Therefore, there is a significant need to understand how these cells change at the epigenomic level over time following infusion into the patient. Methods: We analyzed MART-1 TCR-T products from 8 patients treated under a clinical trial at UCLA (NCT00910650). Samples from the baseline infusion product and samples from day +30 recovered from peripheral circulation were sorted for TCR+ cells via flow cytometry, and were then subjected to whole genome bisulfite sequencing (WGBS), ATACseq, and RNAseq in parallel. Differential chromatin accessibility and gene expression by the ATACseq and RNAseq datasets, respectively, were analyzed via DESeq2, with P adjusted less than 0.1. WGBS datasets were analyzed via Metilene, and differentially methylated regions (DMRs) were defined as those regions with CpG loci containing a methylation difference >= 10% and a P adjusted < 0.05. Functional DMRs were defined as those repressed over time (increased DNA methylation with decreased chromatin accessibility/gene expression relative to infusion product), or activated over time (decreased DNA methylation with increased chromatin accessibility/gene expression relative to infusion product). Functional DMRs were then analyzed via EnrichR to evaluate gene ontology and pathways significantly enriched in gene lists. Results: We collectively identified three genes with repressed DMR activity and 49 genes with activated DMR activity compared to baseline infusion products. Our findings revealed that genes associated with repressed DMRs included IL2RA, FBLN7, and ZNRF1. These genes were collectively associated with a decrease in T-cell activation, cytokine signaling, and migration activity, potentially impacting the functional capabilities of T-cells in the post-infusion environment. Conversely, genes associated with activated DMRs included PDCD1 (PD1), FGR, KIR3DL1, KIR2DL4, and KLF3, with pathway enrichment analysis indicating a significant shift in the T-cell landscape towards reduced anti-tumor activity, decreased T-cell proliferation, T-cell aging, and the promotion of immune escape tumor phenotypes. Conclusions: This comprehensive multi-omics approach showcases an atlas of genes in clinical TCR-T cell therapeutics which are subject to functional changes in DNA methylation over time in vivo. These findings shed light on the complex interplay between DNA methylation, chromatin accessibility, and gene expression in the context of TCR-T cell therapy, with implications for the development of more effective immunotherapeutic strategies. Citation Format: Giulia Protti, Cole Peters, Moe Kawakami, Conner Kidd, Varsha Subramanyam, Analynn Lechien, Andrew Dinh, Antoni Ribas, Matteo Pellegrini, Theodore S. Nowicki. Multiomics analyses reveal functional DNA, methylation pattern changes in clinical transgenic T-cell receptor cell therapy products [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3.

Abstract 3399: Prediction of cardiac adverse events (AE) in trastuzumab treated breast cancer patients (pts) via a comprehensive genomic and DNA methylation blood based assay

Abstract Background: ERBB2 (HER2) targeted therapy is an important therapeutic class used to treat HER2-positive breast cancer (BC) but has been associated with a risk of cardiotoxicity. Identifying pts likely to experience this AE could allow for early intervention and/or a change in treatment plan. Previous studies have demonstrated the ability to detect changes in methylation patterns of pts who had cardiotoxicity from anti-HER2 therapy. Here, we report a retrospective study assessing the feasibility of using the Guardant Infinity platform (genomic and epigenomic NGS analysis) to predict severe cardiac AE in pts treated with trastuzumab. Methods: Samples (n=46) from female pts with BC undergoing treatment with trastuzumab without prior record of heart failure and with a blood sampling <300 days prior to a documented heart failure event defined a positive case cohort. 70 blood samples were matched to the positive case cohort in all above attributes but without record of patient heart failure to comprise a negative cohort. The >20K differentially methylated regions on Guardant Infinity platform may be useful for detection of specific disease attributes such as treatment-associated AE. To explore this, mixture models were first trained using 880 BC samples unrelated to heart failure to distinguish methylation signals coming from tumor versus non-tumor cfDNA. The resulting normalized methylation signals represent the posterior probabilities of the region molecules to be derived from tumor cells. A subset of methylation regions were selected based on significance of association between heart failure status and normalized methylation signals in the positive and negative AE cohorts. A penalized logistic regression model was then trained on the normalized signals of the selected methylation regions to predict whether a patient would have future cardiac AE. Results: A 10-fold cross validation of the penalized logistic regression models trained on normalized methylation signals produced an area under the curve of 0.78 for predicting heart failure status, suggesting feasibility of using blood-based methylation signals to predict cardiac AE on this platform. The differentially methylated regions selected as model predictors show a clear separation in hypermethylation status between positive versus negative cohorts. Conclusion: Our results show the prediction of cardiac AE in BC pts undergoing trastuzumab treatment in advance of documented heart failure using a blood-based assay designed for simultaneous comprehensive genomic and epigenomic profiling. Given the relatively small sample size within this study, further refinement and validation of the classification models is warranted and ongoing. Citation Format: Sean Gordon, Catalin Barbacioru, Daniel Gaile, Denis Tolkunov, Nicole Zhang, Carin Espenschied, Jing Wang, Tara Dinman, Kimberly Banks, Amar Das, Han-Yu Chuang, Helmy Eltoukhy. Prediction of cardiac adverse events (AE) in trastuzumab treated breast cancer patients (pts) via a comprehensive genomic and DNA methylation blood based assay [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3399.

Abstract 2437: Distinct DNA methylation patterns in male urogenital cancers

Abstract Background: Male urogenital cancers including prostate cancer (PCa), bladder cancer (BLCA) and kidney renal cancer (KIRC), account for 38% of the total number of new male cancers. Previous studies have shown that changes in DNA methylation patterns are associated with the occurrence and progression of these cancers. Here, we performed whole-genome bisulfite methylation sequencing (WGBS) on tissue samples from these cancers to comprehensively characterize the methylation patterns to provide insights into the potential biological functions of methylation and to identify possible early detection biomarkers. Methods: Tissue samples were collected from patients with PCa, BLCA and KIRC who had not received any treatment prior to surgery from Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine. Samples with the cancer cells content ≥30% in cancer tissues and no cancer cells in the adjacent tissues was deemed qualified. A total of 43 samples were sequenced by whole-genome bisulfite methylation sequencing (WGBS) with a depth of 30X, including PCa, BLCA, KIRC cancer tissues, and their adjacent cancer tissues. Results: Distinct methylation patterns were observed in the 3 cancers. By comparing cancer and adjacent tissues, the numbers of differentially methylated sites (DMSs) were 21,195 (31% hyperDMSs and 69% hypoDMSs), 587,010 (23% hyperDMSs and 77% hypoDMSs) and 7,855,162 (5% hyperDMSs and 95% hypoDMSs) in PCa, BLCA and KIRC, respectively. The distribution of hyperDMSs and hypoDMSs across various chromosomes was relatively consistent in KIRC and BLCA. However, in PCa, the hypoDMSs were mainly located on chromosome 8 (5265/14666, 36%). Among the three cancers, only 2-3% of hypoDMSs were located in gene promoter regions, while the proportions of hyperDMSs in gene promoter regions were higher with 4%, 8% and 17% for PCa, BLCA and KIRC, respectively. Among the above DMSs, 1901 DMSs-related genes were shared by PCa, BLCA and KIRC and 251, 4252, 2475 DMSs-related genes were unique in PCa, BLCA and KIRC, respectively. Gene Ontology analysis revealed that the shared DMSs-related genes were enriched in Wnt signaling pathway and positive regulation of MAPK cascade. Conclusions: Our present study demonstrated the differential methylation patterns in male urogenital cancers, which may provide insights into the potential biological functions of methylation and to identify possible early detection biomarkers. Citation Format: Guopeng Yu, Jiangyi Wang, Long Li, Wenchuan Xie, Yushan Liu, Qing Yang, Bin Xu. Distinct DNA methylation patterns in male urogenital cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2437.

Nrf2 pre-recruitment at Enhancer 2 is a hallmark of H2 O2 -induced epigenetic transcriptional memory in the HMOX1 gene in human umbilical artery endothelial cells.

Maternal obesity (MO) is a significant cause of increased cardiometabolic risk in offspring, who present endothelial dysfunction at birth. Alterations in physiologic and cellular redox status are strongly associated with altered gene regulation in arterial endothelium. However, specific mechanisms by which the pro-oxidant fetal environment in MO could modulate the vascular gene expression and function during the offspring's postnatal life are elusive. We tested if oxidative stress could reprogram the antioxidant-coding gene's response to a pro-oxidant challenge through an epigenetic transcriptional memory (ETM) mechanism. A pro-oxidant double-hit protocol was applied to human umbilical artery endothelial cells (HUAECs) and EA.hy 926 endothelial cell lines. The ETM acquisition in the HMOX1 gene was analyzed by RT-qPCR. HMOX1 mRNA decay was evaluated by Actinomycin-D treatment and RT-qPCR. To assess the chromatin accessibility and the enrichment of NRF2, RNAP2, and phosphorylation at serin-5 of RNAP2, at HMOX1 gene regulatory regions, were used DNase HS-qPCR and ChIP-qPCR assays, respectively. The CpG methylation pattern at the HMOX1 core promoter was analyzed by DNA bisulfite conversion and Sanger sequencing. Data were analyzed using two-way ANOVA, and p < 0.05 was statistically significant. Using a pro-oxidant double-hit protocol, we found that the Heme Oxygenase gene (HMOX1) presents an ETM response associated with changes in the chromatin structure at the promoter and gene regulatory regions. The ETM response was characterized by a paused-RNA Polymerase 2 and NRF2 enrichment at the transcription start site and Enhancer 2 of the HMOX1 gene, respectively. Changes in DNA methylation pattern at the HMOX1 promoter were not a hallmark of this oxidative stress-induced ETM. These data suggest that a pro-oxidant milieu could trigger an ETM at the vascular level, indicating a potential epigenetic mechanism involved in the increased cardiovascular risk in the offspring of women with obesity.

Identification of dihydromyricetin as a natural DNA methylation inhibitor with rejuvenating activity in human skin.

Changes in DNA methylation patterning have been reported to be a key hallmark of aged human skin. The altered DNA methylation patterns are correlated with deregulated gene expression and impaired tissue functionality, leading to the well-known skin aging phenotype. Searching for small molecules, which correct the aged methylation pattern therefore represents a novel and attractive strategy for the identification of anti-aging compounds. DNMT1 maintains epigenetic information by copying methylation patterns from the parental (methylated) strand to the newly synthesized strand after DNA replication. We hypothesized that a modest inhibition of this process promotes the restoration of the ground-state epigenetic pattern, thereby inducing rejuvenating effects. In this study, we screened a library of 1800 natural substances and 640 FDA-approved drugs and identified the well-known antioxidant and anti-inflammatory molecule dihydromyricetin (DHM) as an inhibitor of the DNA methyltransferase DNMT1. DHM is the active ingredient of several plants with medicinal use and showed robust inhibition of DNMT1 in biochemical assays. We also analyzed the effect of DHM in cultivated keratinocytes by array-based methylation profiling and observed a moderate, but significant global hypomethylation effect upon treatment. To further characterize DHM-induced methylation changes, we used published DNA methylation clocks and newly established age predictors to demonstrate that the DHM-induced methylation change is associated with a reduction in the biological age of the cells. Further studies also revealed re-activation of age-dependently hypermethylated and silenced genes in vivo and a reduction in age-dependent epidermal thinning in a 3-dimensional skin model. Our findings thus establish DHM as an epigenetic inhibitor with rejuvenating effects for aged human skin.

Is developmental plasticity triggered by DNA methylation changes in the invasive cane toad (Rhinella marina)?

Many organisms can adjust their development according to environmental conditions, including the presence of conspecifics. Although this developmental plasticity is common in amphibians, its underlying molecular mechanisms remain largely unknown. Exposure during development to either 'cannibal cues' from older conspecifics, or 'alarm cues' from injured conspecifics, causes reduced growth and survival in cane toad (Rhinella marina) tadpoles. Epigenetic modifications, such as changes in DNA methylation patterns, are a plausible mechanism underlying these developmental plastic responses. Here we tested this hypothesis, and asked whether cannibal cues and alarm cues trigger the same DNA methylation changes in developing cane toads. We found that exposure to both cannibal cues and alarm cues was associated with local changes in DNA methylation patterns. These DNA methylation changes affected genes putatively involved in developmental processes, but in different genomic regions for different conspecific-derived cues. Genetic background explains most of the epigenetic variation among individuals. Overall, the molecular mechanisms triggered by exposure to cannibal cues seem to differ from those triggered by alarm cues. Studies linking epigenetic modifications to transcriptional activity are needed to clarify the proximate mechanisms that regulate developmental plasticity in cane toads.

Kidney-specific methylation patterns correlate with kidney function and are lost upon kidney disease progression

BackgroundChronological and biological age correlate with DNA methylation levels at specific sites in the genome. Linear combinations of multiple methylation sites, termed epigenetic clocks, can inform us the chronological age and predict multiple health-related outcomes. However, why some sites correlating with lifespan, healthspan, or specific medical conditions remain poorly understood. Kidney fibrosis is the common pathway for chronic kidney disease, which affects 10% of European and US populations.ResultsHere we identify epigenetic clocks and methylation sites that correlate with kidney function. Moreover, we identify methylation sites that have a unique methylation signature in the kidney. Methylation levels in majority of these sites correlate with kidney state and function. When kidney function deteriorates, all of these sites regress toward the common methylation pattern observed in other tissues. Interestingly, while the majority of sites are less methylated in the kidney and become more methylated with loss of function, a fraction of the sites are highly methylated in the kidney and become less methylated when kidney function declines. These methylation sites are enriched for specific transcription-factor binding sites. In a large subset of sites, changes in methylation patterns are accompanied by changes in gene expression in kidneys of chronic kidney disease patients.ConclusionsThese results support the information theory of aging, and the hypothesis that the unique tissue identity, as captured by methylation patterns, is lost as tissue function declines. However, this information loss is not random, but guided toward a baseline that is dependent on the genomic loci.Significance statementDNA methylation at specific sites accurately reflects chronological and biological age. We identify sites that have a unique methylation pattern in the kidney. Methylation levels in the majority of these sites correlate with kidney state and function. Moreover, when kidney function deteriorates, all of these sites regress toward the common methylation pattern observed in other tissues. Thus, the unique methylation signature of the kidney is degraded, and epigenetic information is lost, when kidney disease progresses. These methylation sites are enriched for specific and methylation-sensitive transcription-factor binding sites, and associated genes show disease-dependent changes in expression. These results support the information theory of aging, and the hypothesis that the unique tissue identity, as captured by methylation patterns, is lost as tissue function declines.

The Interplay of Varicoceles, Sperm Epigenetics, and Male Infertility: A Focused, Contemporary Review

Despite the wide recognition of varicocele as a contributor to infertility, its exact pathophysiologic mechanism is not fully understood. As the field of male infertility continues to see progress in new diagnostic and therapeutic technologies, we sought to obtain a robust understanding of the interplay of varicoceles, oxidative stress, DNA methylation, and male infertility. We performed a comprehensive review of the contemporary literature in PubMed using search terms and keywords associated with varicoceles, DNA methylation, and male infertility. The most important findings from the literature review were included in this report. Articles were selected based on quality and relevance to the topic. Eight studies were included in this review. These studies discuss DNA methylation and varicocele-associated male infertility through evaluation of sperm parameters, DNA methylation, DNA fragmentation, and other relevant factors. Our review of the literature on varicocele-associated sperm DNA methylation indicates that global hypomethylation occurs in association with varicoceles. Some data suggest a dose-dependent effect of varicocele grade on sperm DNA methylation, with the greatest magnitude changes seen in grades II and III varicoceles. While changes in DNA methylation patterns would be expected following varicocelectomy, such changes were not found to be statistically significant in one study reviewed here. However, current human studies are limited by small sample size and short follow-up time. Future clinical and preclinical studies with robust sample sizes and hypothesis-driven investigations are necessary to further understand the relationship between DNA methylation patterns and varicocele-associated male infertility.

Identification of DNA methylation biomarkers for evaluating cardiovascular disease risk from epigenome profiles altered by low-dose ionizing radiation

BackgroundEnvironmental exposure, medical diagnostic and therapeutic applications, and industrial utilization of radionuclides have prompted a growing focus on the risks associated with low-dose radiation (< 100 mGy). Current evidence suggests that such radiation can induce epigenetic changes. Nevertheless, whether exposure to low-dose radiation can disrupt endothelial cell function at the molecular level is unclear. Because endothelial cells play crucial roles in cardiovascular health and disease, we aimed to investigate whether low-dose radiation could lead to differential DNA methylation patterns at the genomic level in endothelial cell (EC) lines.MethodsWe screened for changes in DNA methylation patterns in primary human aortic (HAECs) and coronary artery endothelial cells following exposure to low-dose ionizing radiation. Using a subset of genes altered via DNA methylation by low-dose irradiation, we performed gene ontology (GO) analysis to predict the possible biological network mediating the effect of low-dose radiation. In addition, we performed comprehensive validation using methylation and gene expression analyses, and ChIP assay to identify useful biomarkers among candidate genes for use in detecting low-dose radiation exposure in human primary normal ECs.ResultsLow-dose radiation is sufficient to induce global DNA methylation alterations in normal EC lines. GO analysis demonstrated that these hyper- or hypo-methylated genes were linked to diverse biological pathways. Our findings indicated a robust correlation between promoter hypermethylation and transcriptional downregulation of four genes (PGRMC1, UNC119B, RERE, and FNDC3B) in response to low-dose ionizing radiation in HAECs.ConclusionsBased on these findings, the identified genes can serve as potential DNA methylation biomarkers for the assessment of cardiovascular risk upon exposure to low-dose radiation.

Long-term effects of myo-inositol on traumatic brain injury: Epigenomic and transcriptomic studies

Background and purposeTraumatic brain injury (TBI) and its consequences remain great challenges for neurology. Consequences of TBI are associated with various alterations in the brain but little is known about long-term changes of epigenetic DNA methylation patterns. Moreover, nothing is known about potential treatments that can alter these epigenetic changes in beneficial ways. Therefore, we have examined myo-inositol (MI), which has positive effects on several pathological conditions. MethodsTBI was induced in mice by controlled cortical impact (CCI). One group of CCI animals received saline injections for two months (TBI+SAL), another CCI group received MI treatment (TBI+MI) for the same period and one group served as a sham-operated control. Mice were sacrificed 4 months after CCI and changes in DNA methylome and transcriptomes were examined. ResultsFor the first time we: (i) provide comprehensive map of long-term DNA methylation changes after CCI in the hippocampus; (ii) identify differences by methylation sites between the groups; (iii) characterize transcriptome changes; (iv) provide association between DNA methylation sites and gene expression. MI treatment is linked with upregulation of genes covering 33 biological processes, involved in immune response and inflammation. In support of these findings, we have shown that expression of BATF2, a transcription factor involved in immune-regulatory networks, is upregulated in the hippocampus of the TBI+MI group where the BATF2 gene is demethylated. ConclusionTBI is followed by long-term epigenetic and transcriptomic changes in hippocampus. MI treatment has a significant effect on these processes by modulation of immune response and biological pathways of inflammation.

Histone 3 Trimethylation Patterns are Associated with Resilience or Stress Susceptibility in a Rat Model of Major Depression Disorder.

Major Depressive Disorder (MDD) is a severe and multifactorial psychiatric condition. Evidence has shown that environmental factors, such as stress, significantly explain MDD pathophysiology. Studies have hypothesized that changes in histone methylation patterns are involved in impaired glutamatergic signaling. Based on this scenario, this study aims to investigate histone 3 involvement in depression susceptibility or resilience in MDD pathophysiology by investigating cellular and molecular parameters related to i) glutamatergic neurotransmission, ii) astrocytic functioning, and iii) neurogenesis. For this, we subjected male Wistar rats to the Chronic Unpredictable Mild Stress (CUMS) model of depression. We propose that by evaluating the sucrose consumption, open field, and object recognition test performance from animals submitted to CUMS, it is possible to predict with high specificity rats with susceptibility to depressive-like phenotype and resilient to the depressive-like phenotype. We also demonstrated, for the first time, that patterns of H3K4me3, H3K9me3, H3K27me3, and H3K36me3 trimethylation are strictly associated with the resilient or susceptible to depressive-like phenotype in a brain-region-specific manner. Additionally, susceptible animals have reduced DCx and GFAP and resilient animals present increase of AQP-4 immunoreactivity. Together, these results provide evidence that H3 trimethylations are related to the development of the resilient or susceptible to depressive-like phenotype, contributing to further advances in the pathophysiology of MDD and the discovery of mechanisms behind resilience.

Exploring Residue-Level Interactions between the Biofilm-Driving R2ab Protein and Polystyrene Nanoparticles.

In biological systems, proteins can bind to nanoparticles to form a "corona" of adsorbed molecules. The nanoparticle corona is of significant interest because it impacts an organism's response to a nanomaterial. Understanding the corona requires knowledge of protein structure, orientation, and dynamics at the surface. A residue-level mapping of protein behavior on nanoparticle surfaces is needed, but this mapping is difficult to obtain with traditional approaches. Here, we have investigated the interaction between R2ab and polystyrene nanoparticles (PSNPs) at the level of individual residues. R2ab is a bacterial surface protein from Staphylococcus epidermidis and is known to interact strongly with polystyrene, leading to biofilm formation. We have used mass spectrometry after lysine methylation and hydrogen-deuterium exchange (HDX) NMR spectroscopy to understand how the R2ab protein interacts with PSNPs of different sizes. Lysine methylation experiments reveal subtle but statistically significant changes in methylation patterns in the presence of PSNPs, indicating altered protein surface accessibility. HDX rates become slower overall in the presence of PSNPs. However, some regions of the R2ab protein exhibit faster than average exchange rates in the presence of PSNPs, while others are slower than the average behavior, suggesting conformational changes upon binding. HDX rates and methylation ratios support a recently proposed "adsorbotope" model for PSNPs, wherein adsorbed proteins consist of unfolded anchor points interspersed with partially structured regions. Our data also highlight the challenges of characterizing complex protein-nanoparticle interactions using these techniques, such as fast exchange rates. While providing insights into how R2ab adsorbs onto PSNP surfaces, this research emphasizes the need for advanced methods to comprehend residue-level interactions in the nanoparticle corona.

DNA Methylation in Ctenophores.

Epigenomic regulation and dynamic DNA methylation, in particular, are widespread mechanisms orchestrating the genome operation across time and species. Whole-genome bisulfite sequencing (WGBS) is currently the only method for unbiasedly capturing the presence of 5-methylcytosine (5-mC) DNA methylation patterns across an entire genome with single-nucleotide resolution. Bisulfite treatment converts unmethylated cytosines to uracils but leaves methylated cytosines intact, thereby creating a map of all methylated cytosines across a genome also known as a methylome. These epigenomic patterns of DNA methylation have been found to regulate gene expression and influence gene evolution rates between species. While protocols have been optimized for vertebrate methylome production, little adaptation has been done for invertebrates. Creating a methylome reference allows comparisons to be made between rates of transcription and epigenomic patterning in animals. Here we present a method of library construction for bisulfite sequencing optimized for non-bilateral metazoans such as the ctenophore, Mnemiopsis leidyi. We have improved upon our previously published method by including spike-in genomic DNA controls to measure methylation conversion rates. By pooling two bisulfite conversion reactions from the same individual, we also produced sequencing libraries that yielded a higher percentage of sequenced reads uniquely mapping to the reference genome. We successfully detected 5-mC in whole-animal methylomes at CpG, CHG, and CHH sites and visualized datasets using circos diagrams. The proof-of-concept tests were performedboth under control conditions and following injury tests with changes in methylation patterns of genes encoding innexins, toxinsand neuropeptides. Our approach can be easily adapted to produce epigenomes from other fragile marine animals.

Molecular monitoring by CDKN2A/p16INK4A and RB1 gene methylation in breast cancer.

This prospective study aimed to provide a comprehensive analysis of the methylation status of two pivotal genes, CDKN2A/p16INK4A (cyclin-dependent kinase inhibitor 2A) and RB1 (retinoblastoma transcriptional corepressor 1), in breast cancer patients. Samples were obtained from 15 women diagnosed with breast cancer and who underwent a total mastectomy. DNA was extracted from the tumor, non-tumor tissue, and peripheral blood (circulating cell-free DNA). The methylation pattern of cell-free DNA extracted from blood collected on the day of mastectomy was compared with the methylation pattern of cell-free DNA from blood collected 1 year post-surgery. The methylation analysis was carried out by sodium bisulfite conversion and polymerase chain reaction, followed by electrophoresis. Methylation of CDKN2A/p16INK4A was identified in 13 tumor samples and 12 non-tumor tissue samples. Two patients exhibited CDKN2A/p16INK4A methylation in the cell-free DNA of the first blood collection, while another showed methylation only in the cell-free DNA of the subsequent blood collection. Regarding RB1, 11 tumors and 8 non-tumor tissue samples presented methylation of the gene. This study presents a novel approach for monitoring breast cancer patients through the analysis of cell-free DNA methylation. This analysis can detect changes in methylation patterns before any visible sign of cancer appears in breast tissue and could help predict the recurrence of malignant breast tumors.

The Relationship Between Vitamin B12 and Telomere Length: A Systematic Review

Telomeres are natural nucleoprotein structures that cover the ends of chromosomes. The phenomenon of telomere shortening, which plays a crucial role in maintaining the stability of the genome, occurs gradually over time when cells undergo division due to the end replication issue. Multiple studies have demonstrated a correlation between telomere shortening and a range of illnesses, including diabetes, dyslipidemia, cardiovascular disease, cancer, and mortality. Diet and lifestyle can affect telomere length. There exists a beneficial association between telomere length and the Mediterranean diet, particularly with regards to the consumption of dietary fiber derived from whole grains and vegetables. Micronutrients such as vitamins and trace elements also play a role in cell metabolism. Some micronutrients, such as vitamin D, folate, and vitamin B12, are associated with telomere biology and cellular aging. Vitamin B12 is essential for DNA synthesis and epigenetic methylation processes. The present systematic review examines the results from clinical trials conducted in humans evaluating the role of vitamin B12 on telomere length. Cellular senescence is a state characterized by inflammation, altered cellular metabolism, genomic instability, and telomere dysfunction, which can be induced by changes in methylation patterns and oxidative stress. Vitamin B12 maintains antioxidative defense. Through these pathways, sufficient amounts of vitamin B12 may potentially play a role in the restoration of DNA damage. Most of the evidence is based on very few randomized clinical trials. Therefore, more extensive prospective cohort studies and better-designed randomized clinical trials are required to validate the correlations outlined in this review.