Zmiany metylacji i oksydacji w próbkach DNA bydła bytującego w środowisku zanieczyszczonym metalami ciężkimi

Epigenetic alterations may influence the metabolic pathways involved in human obesity. We hypothesised that global DNA methylation levels in adipose tissue might be associated with obesity and related phenotypes. We measured global DNA methylation levels in paired samples of subcutaneous adipose tissue (SAT) and omental visceral adipose tissue (OVAT) from 51 individuals, and in leucocytes from 559 Sorbs, a population from Germany, using LUminometric Methylation Assay (LUMA). To further investigate the underlying mechanisms of the observed associations, we measured global methylation levels in 3T3-L1 adipocytes exposed to glucose, insulin and lipids. Global methylation levels (±SD) were significantly higher in OVAT (74.27% ± 2.2%) compared with SAT (71.97% ± 2.4%; paired t test, p < 1 × 10(-9)). Furthermore, global methylation levels in SAT were positive correlates of measures of fat distribution (waist measurement, WHR) and glucose homeostasis (HbA1c) (all p < 0.015 after accounting for multiple testing and covariates). Global methylation levels in the German Sorb cohort were associated with glucose homeostasis, but this association did not withstand adjustment for covariates. Exposure of 3T3-L1 adipocytes to insulin, palmitate and glucose decreased global methylation levels 1h after treatment relative to controls. Our data suggest that the variability in global methylation in adipose tissue might be related to alterations in glucose metabolism.

Association between serum organochlorines and global methylation level of leukocyte DNA among Japanese women: a cross-sectional study

Objective To explore the effects of UVB on the expression of Gadd45a gene and DNA methylation levels in Jurkat cells. Methods Jurkat cells were irradiated with UVB of 1.0 J/cm2 and 1.5 J/cm2 respectively, and collected at 6, 12, 24 and 48 hours after the irradiation. Real-time RT-PCR was used to detect the mRNA expression of Gadd45a gene and methylation-sensitive genes CD11a and CD70. Global methylation level was also measured by MethylAmp global DNA methylation quantification kit. Results After irradiation with UVB at 1.0 J/cm2, the mRNA level of Gadd45a increased but global methylation level decreased at 6, 12, 24 and 48 hours, and significant changes were observed at 6 and 12 hours for the level of both Gadd45a mRNA expression and global methylation (P ＜ 0.01 or 0.05). Elevated mRNA expressions of CD11 a and CD70 were also noted in Jurkat cells after irradiation with UVB of 1.0 J/cm2, and significant elevation was observed at 12 hours (both P ＜ 0.05 ). After irradiation with UVB of 1.5 J/cm2, there was a statistical increase in the mRNA expressions of Gadd45a, CD11 a, CD70, together with a statistical decrease in global methylation level in Jurkat cells, at 6, 12, 24 and 48 hours (P ＜ 0.01 or 0.05). The mRNA expression of Gadd45a negatively correlated with the global level of DNA methylation in Jurkat cells (r = -0.395, P ＜ 0.05). Conclusion UVB irradiation can upregulate the expression of Gadd45a, but downregulate the global DNA methylation level in Jurkat cells. Key words: Ultraviolet ray; Jurkat cells; Methylation

Metabolic reprogramming and genomic instability are two key components in driving carcinogenesis. While it has been theorized that these two processes influence each other, the mechanisms by which metabolic reprogramming can induce genomic instability remain unknown. Our lab previously demonstrated xCT, a cystine/glutamate antiporter, is highly expressed in NSCLC and induces metabolic reprogramming. However, its influence on genomic instability is unknown. In this study, we aim to examine how xCT could potentially contribute to genomic instability by first investigating its influence on the epigenetic landscape, markedly DNA methylation. We hypothesize that changes in intracellular metabolite concentrations due to high xCT expression have a downstream effect on the levels of metabolites involved in DNA methylation, and such changes are significant enough to induce alterations in global DNA methylation. Global methylation levels were quantified through a colorimetric assay in A549 wildtype (WT) and xCT knockout (KO) cells. Next, xCT KO cells were treated with propargylglycine (PAG), a cystathionase inhibitor, and measured global methylation. By inhibiting cystathionase, we blocked cells' ability to synthesize cysteine through the utilization metabolites in the methionine cycle. Quantified methylation levels reported 51.2 ± 11.4% and 25.6 ± 11.0% in WT and xCT KO cells respectively- an average of a 50.0% decrease in methylation upon knocking out xCT. Furthermore, initial data showed DNA methylation more than tripling (234.8% increase) in xCT KO cells when treated with PAG, notably demonstrating 43.4% higher methylation levels than that of treated and untreated WT. Additionally, a western blot revealed that compared to WT, xCT KO cells express much higher levels of cystathionine beta synthase, another enzyme linking cysteine biosynthesis and the methionine cycle. These results support the notion that metabolic activity in the context of xCT can change DNA methylation, potentially through altered metabolic demand between the transsulfuration pathway and methionine cycle. Further studies investigating key metabolite concentrations in xCT KO versus WT cells, as well as analyzing deregulated genes resulting from the altered methylation landscape, will help elucidate the extent of xCT-induced metabolic reprogramming. Understanding the full scope xCT overexpression and the underlying mechanisms leading to epigenetic changes may provide crucial insight to the interplay of metabolic reprogramming and other cancer drivers like genomic instability. By understanding the true origin and influences of such hallmarks of carcinogenesis, more informed approaches can be applied to early preventative therapies. Citation Format: Dalton Hill, S.M. Jamshedur Rahman, Christien Kluwe, Pierre P. Massion. xCT expression alters global DNA methylation levels in lung adenocarcinoma cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 161.

Reduced levels of global DNA methylation are associated with genomic instability and are independent predictors of cancer risk. Little is known about the environmental determinants of global DNA methylation in peripheral blood. We examined the association between demographic and lifestyle factors and levels of global leukocyte DNA methylation in 161 cancer-free subjects enrolled in the North Texas Healthy Heart Study aged 45–75 years in 2008. We used in-person interviews for demographics and lifestyle factors, a self-administrated Block food frequency questionnaire for diet, and bioelectrical impedance analysis and CT-scan for body composition. We measured genomic DNA methylation using bisulfite conversion of DNA and pyrosequencing for LINE-1. Body composition measures including body mass index, waist circumference, areas of subcutaneous fat and visceral fat, percent of fat mass and fat-free mass were not associated with global genomic DNA methylation after controlling the effect of age, gender and race/ethnicity. Instead, female gender was significantly associated with a reduced level of global methylation (β = -2.77, 95% CI: -4.33, -1.22). Compared to non-Hispanic whites, non-Hispanic blacks (β = -2.02, 95% CI: -3.55, -0.50) had significantly lower levels of global methylation. No association was found with age, cigarette smoking, alcohol drinking and dietary intake of nutrients in one-carbon metabolism. Global leukocyte DNA methylation differs by gender and race/ethnicity, suggesting these variables need to be taken into consideration in studies of global DNA methylation as an epigenetic marker for cancer.

Global and HOX Gene DNA Methylation In Normal Karyotype Acute Myeloid Leukemia: Clinical Implications and Molecular Correlations

Global hypomethylation of genomic DNA is associated with genomic instability and carcinogenic processes. The loss of DNA methylation has been reported in several cancers; therefore, global methylation levels have been considered as biomarkers for cancer diagnosis. Bisulfite conversion analysis has been widely used as the gold standard method for quantification of DNA methylation levels. However, this method requires cumbersome and time-consuming steps. To quantify global DNA methylation levels in homogeneous solutions, we exemplify a sensing system based on bioluminescence resonance energy transfer (BRET) using methyl-CpG binding domain (MBD)-fused firefly luciferase (MBD-FLuc) and unmethyl-CpG binding domain (CXXC)-fused firefly luciferase (CXXC-FLuc). MBD-FLuc and CXXC-FLuc bind to methylated and unmethylated CpGs, respectively, in the genomic DNA to excite BOBO-3, an intercalating dye on genomic DNA. These BOBO-3 emission intensities depend on the methylated and unmethylated CpG content. The global DNA methylation levels can be quantified from the BOBO-3 emission intensities. Moreover, we introduce a multicolor BRET assay using MBD-FLuc and CXXC-fused Oplophorus luciferase (CXXC-OLuc) for the simultaneous quantification of methylated and unmethylated CpG content in genomic DNA. CXXC-OLuc excites the BOBO-1 DNA-intercalating dye depending on the unmethylated CpG content. Thus, the emission intensities of BOBO-1 and BOBO-3 excited by CXXC-OLuc and MBD-FLuc, respectively, can be simultaneously measured, thereby enabling the determination of global DNA methylation level in a single step. Here, we describe the detailed protocols for the expression of MBD-FLuc, CXXC-FLuc, and CXXC-OLuc in Escherichia coli and determine the global DNA methylation levels using these BRET assays.

Lower global DNA methylation is associated with genomic instability and it is one of the epigenetic mechanisms relevant to carcinogenesis. Emerging evidence for several cancers suggests that lower overall levels of global DNA methylation in blood are associated with different cancer types, although less is known about breast cancer. We examined global DNA methylation levels using a sibling design in 273 sisters affected with breast cancer and 335 unaffected sisters from the New York site of the Breast Cancer Family Registry. We measured global DNA methylation in total white blood cell (WBC) and granulocyte DNA by two different methods, the [3H]-methyl acceptance assay and the luminometric methylation assay (LUMA). Global methylation levels were only modestly correlated between sisters discordant for breast cancer (Spearman correlation coefficients ranged from -0.08 to 0.24 depending on assay and DNA source). Using conditional logistic regression models, women in the quartile with the lowest DNA methylation levels (as measured by the [3H]-methyl acceptance assay) had a 1.8-fold (95% CI = 1.0–3.3) higher relative association with breast cancer than women in the quartile with the highest DNA methylation levels. When we examined the association on a continuous scale, we also observed a positive association (odds ratio, OR = 1.3, 95% CI = 1.0–1.7, for a one unit change in the natural logarithm of the DPM/μg of DNA). We observed no association between measures by the LUMA assay and breast cancer risk. If replicated in prospective studies, this study suggests that global DNA methylation levels measured in WBC may be a potential biomarker of breast cancer risk even within families at higher risk of cancer.

BackgroundThe change in epigenetic signatures, in particular DNA methylation, has been proposed as risk markers for various age-related diseases. However, the course of variation in methylation levels with age, the difference in methylation between genders, and methylation-disease association at the whole genome level is unclear. In the present study, genome-wide methylation levels in DNA extracted from peripheral blood for 2116 healthy Chinese in the 2–97 age range and 280 autistic trios were examined using the fluorescence polarization-based genome-wide DNA methylation quantification method developed by us.ResultsGenome-wide or global DNA methylation levels proceeded through multiple phases of variation with age, consisting of a steady increase from age 2 to 25 (r = 0.382) and another rise from age 41 to 55 to reach a peak level of ~80 % (r = 0.265), followed by a sharp decrease to ~40 % in the mid-1970s (age 56 to 75; r = −0.395) and leveling off thereafter. Significant gender effect in methylation levels was observed only for the 41–55 age group in which methylation in females was significantly higher than in males (p = 0.010). In addition, global methylation level was significantly higher in autistic children than in age-matched healthy children (p < 0.001).ConclusionsThe multiphasic nature of changes in global methylation levels with age was delineated, and investigation into the factors underlying this profile will be essential to a proper understanding of the aging process. Furthermore, this first report of global hypermethylation in autistic children also illustrates the importance of age-matched controls in characterization of disease-associated variations in DNA methylation.Electronic supplementary materialThe online version of this article (doi:10.1186/s40246-016-0086-y) contains supplementary material, which is available to authorized users.

BackgroundChronic inflammatory conditions are associated with higher tumor incidence through epigenetic and genetic alterations. Here, we focused on an association between an inflammation marker, C-reactive-protein (CRP), and global DNA methylation levels of peripheral blood leukocytes.MethodsThe subjects were 384 healthy Japanese women enrolled as the control group of a case-control study for breast cancer conducted from 2001 to 2005. Global DNA methylation was quantified by Luminometric Methylation Assay (LUMA).ResultsWith adjustment for lifestyle-related factors, including folate intake, the global DNA methylation level of peripheral blood leukocytes was significantly but weakly increased by 0.43% per quartile category for CRP (P for trend = 0.010). Estimated methylation levels stratified by CRP quartile were 70.0%, 70.8%, 71.4%, and 71.3%, respectively. In addition, interaction between polymorphism of MTHFR (rs1801133, known as C677T) and CRP was significant (P for interaction = 0.046); the global methylation level was significantly increased by 0.61% per quartile category for CRP in the CT/TT group (those with the minor allele T, P for trend = 0.001), whereas no association was observed in the CC group (wild type).ConclusionsOur study suggests that CRP concentration is weakly associated with global DNA methylation level. However, this association was observed more clearly in individuals with the minor allele of the MTHFR missense SNP rs1801133. By elucidating the complex mechanism of the regulation of DNA methylation by both acquired and genetic factors, our results may be important for cancer prevention.

Exposure to different early-life stress experiences results in differentially altered DNA methylation in the brain and immune system

Iodine excess did not affect the global DNA methylation status and DNA methyltransferase expression in T and B lymphocytes from NOD.H-2h4 and Kunming mice

DNA methylation is one of the mechanisms of epigenetic regulation and is observed in mammals to maintain a normal expression pattern of the genes. Aberrant profiles of DNA methylation have already been associated with cardiovascular diseases. We evaluated 190 patients with Acute Coronary Syndrome (ACS) and 75 patients without ACS (non-ACS). Patient severity was assessed by the TIMI risk score, and both levels of global DNA methylation (ACS = 190; non-ACS = 75), stratified in expected group (male ≥ 65 years; female ≥ 55 years) and early group (male < 65 years; female < 55 years). As results, the ACS and non-ACS groups showed different levels of global DNA methylation, and patients with ACS were more methylated (p = 0.0121). Patients with ACS, showed a difference (p < 0.0001) in methylation profiles between groups. The low TIMI group had a higher level of DNA methylation, while the intermediate / high group showed a decreased methylation pattern. A negative correlation was observed between the level of global methylation and the increase in age (p = 0.0387; r = −0.15), which became hypomethylated over the years. The hypermethylated global DNA profile by its association with the development of ACS can be a potential biomarker.

Purpose: We investigated the association between occupational radiation exposure and DNA methylation changes in nuclear power plant workers. We also evaluated whether radiation- induced DNA methylation alterations are associated with chromosome aberrations.Materials and methods: The study population included 170 radiation-exposed workers and 30 controls. We measured global, long interspersed nuclear element-1 (LINE-1), and satellite 2 methylation levels in blood leukocyte DNA. The analysis of chromosome aberrations was performed on peripheral lymphocytes.Results: Global DNA methylation levels were lower in radiation-exposed workers than in controls. The methylation levels were negatively associated with the recent 1.5-year radiation dose in a multiple linear regression model (β = − 0.0088, p ≤ 0.001); the levels increased proportionally with the total cumulative dose in radiation-exposed workers. LINE-1 methylation levels were higher in radiation-exposed workers than in controls and were significantly associated with the total cumulative radiation dose in a multiple linear regression model (β = − 0.031, p = 0.035). Global DNA methylation levels were also correlated with chromosome aberrations among workers. Workers with low global methylation levels had a higher frequency of chromosome aberrations than did subjects with high global methylation levels.Conclusion: Occupational exposure to low-dose radiation could affect DNA methylation levels, and the radiation-induced DNA methylation alterations may be associated with chromosome aberrations.

Dysregulated DNA methylation in lymphocytes has been linked to autoimmune disorders. The aims of this study were to identify global DNA methylation patterns in patients with autoimmune thyroid diseases and to observe methylation changes after treatment for these conditions. A cross-sectional study was conducted, including the following patients: 51 with newly diagnosed Graves' disease (GD), 28 with autoimmune hypothyroidism (AIT), 29 with positive thyroid autoantibodies, and 39 matched healthy volunteers. Forty GD patients treated with radioiodine or antithyroid drugs and 28 AIT patients treated with L-thyroxine were followed for three months. Serum free triiodothyronine, free thyroxine, thyrotropin, thyroid peroxidase antibodies, thyroglobulin antibodies, and thyrotropin receptor antibodies were assayed using electrochemiluminescent immunoassays. CD3+ T and CD19+ B cells were separated by flow cytometry for total DNA and RNA extraction. Global DNA methylation levels were determined by absorptiometry using a methylation quantification kit. DNA methyltransferase (DNMT) expression levels were detected by real-time polymerase chain reaction. Hypomethylation and down-regulated DNMT1 expression in T and B lymphocytes were observed in the newly diagnosed GD patients. Neither the AIT patients nor the positive thyroid autoantibodies patients exhibited differences in their global DNA methylation status or DNMT mRNA levels compared with healthy controls. Antithyroid drugs restored global methylation and DNMT1 expression in both T and B lymphocytes, whereas radioiodine therapy affected only T cells. L-thyroxine replacement did not alter the methylation or DNMT expression levels in lymphocytes. The global methylation levels of B cells were negatively correlated with the serum thyroid peroxidase antibodies in patients with autoimmune thyroid diseases. Hyperthyroid patients with newly diagnosed GD had global hypomethylation and lower DNMT1 expression in T and B lymphocytes. The results provide the first demonstration that antithyroid drugs or radioiodine treatment restore global DNA methylation and DNMT1 expression with concurrent relief of hyperthyroidism.