One-carbon Metabolism Pathway Research Articles

Genetic Variants in One-Carbon Metabolism Pathway Predict Survival Outcomes of Early-Stage Non-Small Cell Lung Cancer

Background: This study was conducted to investigate the association between genetic variants in one-carbon metabolism and survival outcomes of surgically resected non-small cell lung cancer (NSCLC). Methods: We genotyped 41 potentially functional variants of 19 key genes in the one-carbon metabolism pathway among 750 NSCLC patients who underwent curative surgery. The association between genetic variants and overall survival (OS)/disease-free survival (DFS) were analyzed. Results: Among the 41 single-nucleotide polymorphisms (SNPs) analyzed, 4 SNPs (MTHFD1L rs6919680T>G and rs3849794T>C, MTR rs2853523C>A, and MTHFR rs4846049G>T) were significantly associated with survival outcomes. MTHFD1L rs6919680T>G and MTR rs2853523C>A were significantly associated with better OS (adjusted hazard ratio [aHR] = 0.73, 95% confidence interval [CI] = 0.54–0.99, p = 0.04) and worse OS (aHR = 2.14, 95% CI = 1.13–4.07, p = 0.02), respectively. MTHFD1L rs3849794T>C and MTHFR rs4846049G>T were significantly associated with worse DFS (aHR = 1.41, 95% CI = 1.08–1.83, p = 0.01; and aHR = 1.97, 95% CI = 1.10–3.53, p = 0.02, respectively). When the patients were divided according to histology, the associations were significant only in squamous cell carcinoma (SCC), but not in adenocarcinoma (AC). In SCC, MTHFD1L rs6919680T>G and MTR rs2853523C>A were significantly associated with better OS (aHR = 0.64, 95% CI = 0.41–1.00, p = 0.05) and worse OS (aHR = 2.77, 95% CI = 1.11–6.91, p = 0.03), respectively, and MTHFD1L rs3849794T>C and MTHFR rs4846049G>T were significantly associated with worse DFS (aHR = 1.73, 95% CI = 1.17–2.56, p = 0.01; and aHR = 2.78, 95% CI = 1.12–6.88, p = 0.03, respectively). Conclusions: Our results suggest that the genetic variants in the one-carbon metabolism pathway could be used as biomarkers for predicting the clinical outcomes of patients with early-stage NSCLC.

Congenital diaphragmatic hernia and maternal dietary nutrient pathways and diet quality.

We examined the association of congenital diaphragmatic hernia (CDH) with maternal dietary intake, using semi-Bayes hierarchical models and principal components analysis to consider intake of nutrients that contribute to one-carbon metabolism and oxidative stress pathways, and a diet quality index. We included data on 825 cases and 11,108 nonmalformed controls born from 1997-2011 whose mother participated in the National Birth Defects Prevention Study (NBDPS), a multisite, population-based case-control study. Exposure data were from maternal telephone interviews, which included a food frequency questionnaire. Adjusted odds ratios (aOR) and 95% confidence intervals (CI) were generated from logistic regression models that included nutritional factors as continuous variables and were adjusted for maternal energy intake, race-ethnicity, parity, and vitamin supplement intake. In the semi-Bayes hierarchical model that included all nutrients and confounders, riboflavin was the only nutrient for which the 95% CI excluded 1.0; the aOR for a 1 SD increase was 0.83. The aORs were 0.79 (95% CI 0.69-0.91) for the one-carbon metabolism pathway score, 0.90 (95% CI 0.80-1.01) for oxidative stress, and 0.85 (95% CI 0.77-0.93) for diet quality (the aORs correspond to a 1 SD increase). The findings from this study provide some support for the hypothesis that better prepregnancy nutrition is associated with reduced risk for CDH. These results provide etiologic clues but should be interpreted with caution given the novelty of the investigation.

CpG-SNP site methylation regulates allele-specific expression of MTHFD1 gene in type 2 diabetes

AbstractThe interaction of genetic and epigenetic mechanisms is one of the underlying causes of phenotypic variability in complex diseases such as type 2 diabetes (T2D). To explore the influence of genetic and epigenetic changes in T2D, we examined the effect of methylation of CpG-SNP sites on allele-specific expression (ASE) in one-carbon metabolism pathway genes in T2D. Case-control study was conducted on 860 individuals (430 T2D and 430 controls). CpG-SNPs shortlisted through in silico analysis were genotyped using tetra ARMS PCR and validated using Sanger DNA sequencing. Global DNA methylation was carried out using RP-HPLC. Promoter DNA methylation and CpG site-specific methylation were carried out using bisulfite sequencing. mRNA expression and ASE were examined by SYBR green and TaqMan assay, respectively. Four exonic CpG-SNPs of MTHFD1, MTRR, and GGH genes were identified in folate pathway genes. Among these, MTHFD1 rs2236225 showed significant association with T2D independent of obesity, displayed ASE, and correlated with CpG-SNP site-specific methylation when compared with controls. Our results demonstrate that SNP rs2236225 in the CpG site of MTHFD1, which regulates allele-specific gene expression in PBMCs is methylation dependent and may perturb one-carbon metabolism pathway in T2D subjects.The interaction of genetic and epigenetic mechanisms is one of the underlying causes of phenotypic variability in diseases like type 2 diabetes. The authors identified the methylation-dependent CpG-SNP in the MTHFD1 gene as a regulator of allele-specific gene expression in peripheral blood mononuclear cells, which may perturb one-carbon metabolism in diabetes.

Formaldehyde formation in the glycine cleavage system and its use for an aldolase-based biosynthesis of 1,3-propanediol

Glycine cleavage system (GCS) occupies a key position in one-carbon (C1) metabolic pathway and receives great attention for the use of C1 carbons like formate and CO2 via synthetic biology. In this work, we demonstrate that formaldehyde exists as a substantial byproduct of the GCS reaction cycle. Three causes are identified for its formation. First, the principal one is the decomposition of N5,N10-methylene-tetrahydrofolate (5,10-CH2-THF) to form formaldehyde and THF. Increasing the rate of glycine cleavage promotes the formation of 5,10-CH2-THF, thereby increasing the formaldehyde release rate. Next, formaldehyde can be produced in the GCS even in the absence of THF. The reason is that T-protein of the GCS can degrade methylamine-loaded H-protein (Hint) to formaldehyde and ammonia, accompanied with the formation of dihydrolipoyl H-protein (Hred), but the reaction rate is less than 0.16% of that in the presence of THF. Increasing T-protein concentration can speed up the release rate of formaldehyde by Hint. Finally, a certain amount of formaldehyde can be formed in the GCS due to oxidative degradation of THF. Based on a formaldehyde-dependent aldolase, we elaborated a glycine-based one carbon metabolic pathway for the biosynthesis of 1,3-propanediol (1,3-PDO) in vitro. This work provides quantitative data and mechanistic understanding of formaldehyde formation in the GCS and a new biosynthetic pathway of 1,3-PDO.

Association between gene promoter methylation of the one-carbon metabolism pathway and serum folate among patients with hyperhomocysteinemia.

Age and lower folate concentrations are well-known risk factors for cardiovascular disease (CVD), but the potential roles of age and folate deficiency in hyperhomocysteinemia (HHcy), especially in HHcy patients with abnormal methylation levels of key enzyme genes promoter in homocysteinemia (Hcy) pathway, have not been thoroughly evaluated. The purpose of this study was to evaluate the relationship between the promoter methylation levels of six key enzyme genes and age and serum folate level to better understand the pathogenesis of HHcy. In 299 HHcy patients, six key enzyme genes promoter methylation was analyzed by PCR amplification and MethylTargetTM methods. The betaine homocysteine methyltransferase (BHMT), Cystathionine β-synthase (CBS), and Methionine synthasegene (MTR) promoter methylation levels were positively associated with age and a negative correlation was found between CBS promoter methylation level and folate levels. However, these associations were not significant after Bonferroni correction. The stratified analysis showed that the methylation level of CBS gene promoter was positively correlated with age in males, and a positive correlation was also found between BHMT gene promoter methylation level and age in HHcy patients with a history of diabetes or hypertension. Moreover, stratified analysis according to sex revealed that the methylation levels of three CpG regions of BHMT_2, CBS_2, and CBS_3 were positively correlated with age in males after Bonferroni correction. Our data suggested that age and folate deficiency may increase the risk of HHcy by mediating methylation of the promoter regions of key enzyme genes in the one-carbon metabolism pathway.

Monomeric NADH-Oxidizing Methylenetetrahydrofolate Reductases from Mycobacterium smegmatis Lack Flavin Coenzyme.

5,10-Methylenetetrahydrofolate reductase (MetF/MTHFR) is an essential enzyme in one-carbon metabolism for de novo biosynthesis of methionine. Our in vivo and in vitro analyses of MSMEG_6664/MSMEI_6484, annotated as putative MTHFR in Mycobacterium smegmatis, failed to reveal their function as MTHFRs. However, we identified two hypothetical proteins, MSMEG_6596 and MSMEG_6649, as noncanonical MTHFRs in the bacterium. MTHFRs are known to be oligomeric flavoproteins. Both MSMEG_6596 and MSMEG_6649 are monomeric proteins and lack flavin coenzymes. In vitro, the catalytic efficiency (kcat/Km ) of MSMEG_6596 (MTHFR1) for 5,10-CH2-THF and NADH was ∼13.5- and 15.3-fold higher than that of MSMEG_6649 (MTHFR2). Thus, MSMEG_6596 is the major MTHFR. This interpretation was further supported by better rescue of the E. coli Δmthfr strain by MTHFR1 than by MTHFR2. As identified by liquid chromatography-tandem mass spectrometry, the product of MTHFR1- or MTHFR2-catalyzed reactions was 5-CH3-THF. The M. smegmatis Δmsmeg_6596 strain was partially auxotrophic for methionine and grew only poorly without methionine or without being complemented with a functional copy of MTHFR1 or MTHFR2. Furthermore, the Δmsmeg_6596 strain was more sensitive to folate pathway inhibitors (sulfachloropyridazine, p-aminosalicylic acid, sulfamethoxazole, and trimethoprim). The studies reveal that MTHFR1 and MTHFR2 are two noncanonical MTHFR proteins that are monomeric and lack flavin coenzyme. Both MTHFR1 and MTHFR2 are involved in de novo methionine biosynthesis and required for antifolate resistance in mycobacteria.IMPORTANCE MTHFR/MetF is an essential enzyme in a one-carbon metabolic pathway for de novo biosynthesis of methionine. MTHFRs are known to be oligomeric flavoproteins. Our in vivo and in vitro analyses of Mycobacterium smegmatis MSMEG_6664/MSMEI_6484, annotated as putative MTHFR, failed to reveal their function as MTHFRs. However, we identified two of the hypothetical proteins, MSMEG_6596 and MSMEG_6649, as MTHFR1 and MTHFR2, respectively. Interestingly, both MTHFRs are monomeric and lack flavin coenzymes. M. smegmatis deleted for the major mthfr (mthfr1) was partially auxotroph for methionine and more sensitive to folate pathway inhibitors (sulfachloropyridazine, para-aminosalicylic acid, sulfamethoxazole, and trimethoprim). The studies reveal that MTHFR1 and MTHFR2 are novel MTHFRs involved in de novo methionine biosynthesis and required for antifolate resistance in mycobacteria.

Homozygous Mutation in the MTHFS Gene May Contribute to the Development of Cerebral Folate Deficiency Syndrome

Objective: The purpose of this study was to examine the role of rare variants in the one-carbon metabolic pathway in the etiology of the cerebral folate deficiency (CFD) syndrome. The CFD syndrome is a neurometabolic syndrome identified by low concentrations of 5-methyltetrahydrofolate (5-MTHF) in the cerebrospinal fluid (CSF) in spite of near-normal peripheral folate levels resulting in neurodevelopmental disorders. Methods: The localized folate metabolism impairments in CFD are thought to be either the result of mutations in genes responsible for folate transport or folate turnover through degradation. Genes that have been previously implicated in the etiology of CFD include folate receptor alpha-1 (FOLR1), dihydrofolate reductase, proton-coupled folate transporter, and capicua. We performed whole-exome sequencing (WES) analysis of a CFD patient that revealed 99 novel missense mutations, of which 21 were classified as damaging mutations through the Poly-Phen2 prediction algorithm. In vitro functional studies were conducted by transient transfection of wild-type and mutant MTHFS into HEK293T cells to determine the impact of the variants on enzyme activity. Results: Of the damaging variants identified in the WES studies, we focused on the gene coding for the enzyme 5,10-methenyl-tetrahydrofolate synthetase (MTHFS). This enzyme catalyzes the production of methenyl THF which is subsequently converted to 5-MTHF. The CFD patient described within was found to carry a homozygous mutation, c.101G>T (p.R34L, rs200058464) in MTHFS, while the parents of the proband are heterozygotes for the MTHFS gene, and the healthy sibling is not a carrier. Conclusion: The mutant allele displayed a 50% reduction in luciferase activity (P

NADH Ties One-Carbon Metabolism to Cellular Respiration

In this issue of Cell Metabolism, Yang etal., 2020 report that serine is a source of mitochondrial NADH derived from one-carbon metabolism. Serine becomes a major source of NADH when cellular respiration is inhibited, and the un-utilized, accumulated NADH inhibits the TCA cycle and slows proliferation.

The Role of Non-Glycolytic Glucose Metabolism in Myocardial Recovery Following Mechanical Unloading and Circulatory Support in Chronic Heart Failure

Following left ventricular assist device (LVAD) mechanical unloading significant improvements in myocardial structure and function have been reported in some advanced heart failure (HF) patients, termed as Responders (R). Our prior work demonstrated a post-LVAD mismatch of glycolysis and oxidative phosphorylation characterized by upregulation of glycolysis without subsequent increase in pyruvate oxidation via the Krebs cycle. We hypothesized that the accumulated glycolytic intermediates are channeled into cardioprotective and repair pathways, such as the pentose phosphate pathway (PPP) and one-carbon metabolism (OCM), which may mediate myocardial structural and functional improvement in Responders. We prospectively obtained myocardial tissue from Non-Failing Donor hearts (n=15) and from Responders (n=11) and Non-Responders (n=30) at LVAD implant (Pre-LVAD) and later at transplantation (Post-LVAD). Responders and Non-Responders were defined based on prior published criteria. We conducted protein expression and metabolite profiling and evaluated mitochondrial structure using electron microscopy. Western blot analysis of key PPP and OCM rate-limiting enzymes, glucose-6-phosphate dehydrogenase and phosphoglycerate dehydrogenase were significantly increased in Post-LVAD Responders (Post-R). In agreement with these findings the metabolite levels of these enzyme substrates such as sedoheptulose-6-phosphate (PPP) and serine and glycine (OCM) were decreased in Post-R. Furthermore, Post-R had significantly higher NADPH levels, reduced ROS levels, improved mitochondrial dynamics and enhanced glycosylation of the extracellular matrix (ECM) protein, α-dystroglycan, indicating increased flux of glucose into the PPP and OCM pathways and all together these findings correlated with the observed myocardial structural and functional improvement. The recovering human heart appears to direct glycolytic metabolites into the PPP and OCM pathways which could contribute to cardioprotection and improved myocardial function by generating NADPH to enhance biosynthesis for repair and by reducing oxidative stress.

MTRR gene variant rs1801394 found in Malaysian patients with neural tube defects

Neural tube defects (NTDs) are congenital anomalies resulting from the failure of neural tube closure during embryogenesis. The precise molecular mechanisms underlying this multifactorial disease is poorly understood, although single nucleotide polymorphisms in genes involved in the one-carbon metabolism cycle are believed to contribute towards NTD development. Among them is 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR). Protein function prediction algorithms (PolyPhen-2, PROVEAN, SIFT, SMART-Ensembl) were employed to evaluate its pathogenicity potential caused by the replacement of isoleucine with methionine. Seven NTD patients and 12 of their parents were recruited for this study. DNA samples were collected through blood or saliva whereby the extracted DNAs were then sent for whole exome sequencing (WES). Zygosity of the variant was confirmed from WES data of each subject and further validated through polymerase chain reaction (PCR) and Sanger sequencing. The results revealed that 57% of patients and 83% of parents carried rs1801394 mutation in their MTRR gene, based on either homozygous (G/G) or heterozygous (A/G) genotypes. Bioinformatics analysis of this missense mutation predicted that this change is damaging to MTRR protein function by 2 of the 3 predictor algorithms and that the change from isoleucine to methionine amino acid affects flavodoxin domain of the protein. This impacts enzyme activity within the one-carbon metabolism pathway, which is linked to the aetiology of NTDs. From population databases, this variant was considered common with a MAF >0.3, however, it was not found in the Singapore Genome Variation Project (SGVP), whose population is a closer representation of the Malaysian subjects investigated here. Hence, we explored the prevalence of this variant in other studies and found that its association with NTDs differed across populations worldwide. Finally, we conclude that rs1801394 may be an NTD risk factor in the Malaysian population and should be further investigated as a potential prenatal screening tool.

Duality of Tocopherol Isoforms and Novel Associations with Vitamins Involved in One-Carbon Metabolism: Results from an Elderly Sample of the LifeLines Cohort Study

Whether the affinity of serum vitamin E with total lipids hampers the appropriate assessment of its association with age-related risk factors has not been investigated in epidemiological studies. We aimed to compare linear regression-derived coefficients of the association of non-indexed and total lipids-indexed vitamin E isoforms with clinical and laboratory characteristics pertaining to the lipid, metabolic syndrome, and one-carbon metabolism biological domains. We studied 1429 elderly subjects (non-vitamin supplement users, 60–75 years old, with low and high socioeconomic status) from the population-based LifeLines Cohort and Biobank Study. We found that the associations of tocopherol isoforms with lipids were inverted in total lipids-indexed analyses, which may be indicative of overcorrection. Irrespective of the methods of standardization, we consistently found positive associations of α-tocopherol with vitamins of the one-carbon metabolism pathway and inverse associations with characteristics related to glucose metabolism. The associations of γ-tocopherol were often opposite to those of α-tocopherol. These data suggest that tocopherol isoforms and one-carbon metabolism are related, with beneficial and adverse associations for α-tocopherol and γ-tocopherol, respectively. Whether tocopherol isoforms, or their interplay, truly affect the one-carbon metabolism pathway remains to be further studied.

Methionine dietary supplementation potentiates ionizing radiation-induced gastrointestinal syndrome.

Methionine is an essential amino acid needed for a variety of processes in living organisms. Ionizing radiation depletes tissue methionine concentrations and leads to the loss of DNA methylation and decreased synthesis of glutathione. In this study, we aimed to investigate the effects of methionine dietary supplementation in CBA/CaJ mice after exposure to doses ranging from 3 to 8.5 Gy of 137Cs of total body irradiation. We report that mice fed a methionine-supplemented diet (MSD; 19.5 vs. 6.5 mg/kg in a methionine-adequate diet, MAD) developed acute radiation toxicity at doses as low as 3 Gy. Partial body irradiation performed with hindlimb shielding resulted in a 50% mortality rate in MSD-fed mice exposed to 8.5 Gy, suggesting prevalence of radiation-induced gastrointestinal syndrome in the development of acute radiation toxicity. Analysis of the intestinal microbiome demonstrated shifts in the gut ecology, observed along with the development of leaky gut syndrome and bacterial translocation into the liver. Normal gut physiology impairment was facilitated by alterations in the one-carbon metabolism pathway and was exhibited as decreases in circulating citrulline levels mirrored by decreased intestinal mucosal surface area and the number of surviving crypts. In conclusion, we demonstrate that a relevant excess of methionine dietary intake exacerbates the detrimental effects of exposure to ionizing radiation in the small intestine.NEW & NOTEWORTHY Methionine supplementation, instead of an anticipated health-promoting effect, sensitizes mice to gastrointestinal radiation syndrome. Mechanistically, excess of methionine negatively affects intestinal ecology, leading to a cascade of physiological, biochemical, and molecular alterations that impair normal gut response to a clinically relevant genotoxic stressor. These findings speak toward increasing the role of registered dietitians during cancer therapy and the necessity of a solid scientific background behind the sales of dietary supplements and claims regarding their benefits.

Association of Intake Folate and Related Gene Polymorphisms with Breast Cancer.

Breast cancer is one of the most common malignancies in women worldwide and is associated with a variety of risk factors. Folate and vitamin B12 are key elements of the one-carbon metabolism pathway where methylenetetrahydrofolate reductase (MTHFR) plays a significant role. Though many molecular and epidemiological studies have been performed to explore the relationship between intake folate, vitamin B12, MTHFR gene polymorphism and breast cancer risk, there is no consensus to date. By reviewing the relevant literatures and summarizing the potential effect of dietary folate intake on MTHFR genes polymorphism and breast cancer risk, we conclude that MTHFR C677T gene polymorphism is associated with breast cancer risk among Asian, but not Caucasians, and the MTHFR A1298C gene polymorphism is not a susceptibility factor of breast cancers. Concomitant low activity of MTHFR enzyme resulted from C677T gene polymorphism and low dietary folate intake is associated with increased breast cancer risk.

Hepatic one-carbon metabolism enzyme activities and intermediate metabolites are altered by prepartum body condition score and plane of nutrition in grazing Holstein dairy cows

Precalving feeding level and body condition score (BCS) alter postcalving energy balance and oxidant status of dairy cows. We hypothesized that the reported benefits of a controlled restriction precalving depend on precalving BCS. The objective was to identify alterations in activity and intermediates of the hepatic one-carbon metabolism, transsulfuration, and tricarboxylic acid pathways. Twenty-eight pregnant and nonlactating grazing dairy cows of mixed age and breed (Friesian, Friesian × Jersey) were randomly allocated to 1 of 4 treatment groups in a 2 × 2 factorial design: 2 prepartum BCS categories [4.0 (thin, BCS4) and 5.0 (optimal, BCS5); 10-point scale], by managing cows in late lactation to achieve the 2 groups at dry-off, and 2 levels of energy intake during the 3 wk preceding calving (75 or 125% of estimated requirements), obtained via allowance (m2/cow) of fresh pasture composed of mostly perennial ryegrass and white cover. Average (± standard deviation) age was 6 ± 2, 6 ± 3, 5 ± 1, and 7 ± 3 yr for BCS4 fed 75 and 125%, and BCS5 fed 75 and 125%, respectively. Breed distribution (average ± standard deviation) for the 4 groups was 79 ± 21, 92 ± 11, 87 ± 31, and 74 ± 23% Friesian, and 17 ± 20, 8 ± 11, 13 ± 31, and 25 ± 23% Jersey. Liver tissue was collected by biopsy at -7, 7, and 28 d relative to calving. Tissue was used for 14C radio-labeling assays to measure betaine-homocysteine S-methyltransferase, 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), and cystathionine-β-synthase (CBS) activity. Liver metabolomics was undertaken using a targeted liquid chromatography with tandem mass spectrometry-based profiling approach. After initial liquid chromatography separation, mass spectra were acquired under both positive and negative ionization, whereas multiple reaction monitoring was used to measure target compound signal response (peak area count). Enzyme activity and metabolite peak area count were normalized with the homogenate protein concentration. Repeated measures analysis of variance via PROC MIXED in SAS (SAS Institute Inc., Cary, NC), with BCS, feeding, and time as fixed effects, and cow as random effect was used. All enzyme activities were affected by time, with betaine-homocysteine S-methyltransferase activity peaking at 7 d, whereas CBS and MTR activity decreased postpartum. Overall, thin cows had greater MTR activity, whereas cows fed 125% requirements had greater CBS activity. An interaction was detected between BCS and feeding for CBS activity, as thin cows fed 125% of requirements had greater overall activity. Compared with liver from BCS4 cows, BCS5 cows had overall greater betaine, glycine, butyrobetaine/acetylcholine, serine, and taurine concentrations. The same metabolites, plus choline and N-N-dimethylglycine, were overall greater in liver of cows fed 75% compared with those fed 125% of requirements. An interaction of BCS and feeding level was detected for the aforementioned metabolites plus methionine, cystathionine, cysteinesulfinate, and hypotaurine, due to greater overall concentrations in BCS5 cows fed 75% of requirements compared with other groups. Overall, differences in hepatic enzyme activity and intermediate metabolites suggest that both BCS and feeding level can alter the internal antioxidant system (e.g., glutathione and taurine) throughout the periparturient period. Further studies are needed to better understand potential mechanisms involved.

Alcohol consumption and serum metabolite concentrations in young women.

Alcohol consumption is an established breast cancer risk factor, though further research is needed to advance our understanding of the mechanism underlying the association. We used global metabolomics profiling to identify serum metabolites and metabolic pathways that could potentially mediate the alcohol-breast cancer association. A cross-sectional analysis of reported alcohol consumption and serum metabolite concentrations was conducted among 211 healthy women 25-29years old who participated in the Dietary Intervention Study in Children 2006 Follow-Up Study (DISC06). Alcohol-metabolite associations were evaluated using multivariable linear mixed-effects regression. Alcohol was significantly (FDR p < 0.05) associated with several serum metabolites after adjustment for diet composition and other potential confounders. The amino acid sarcosine, the omega-3 fatty acid eicosapentaenoate, and the steroid 4-androsten-3beta,17beta-diol monosulfate were positively associated with alcohol intake, while the gamma-tocopherol metabolite gamma-carboxyethyl hydroxychroman (CEHC) was inversely associated. Positive associations of alcohol with 2-methylcitrate and 4-androsten-3beta,17beta-diol disulfate were borderline significant (FDR p < 0.10). Metabolite set enrichment analysis identified steroids and the glycine pathway as having more members associated with alcohol consumption than expected by chance. Most of the metabolites associated with alcohol in the current analysis participate in pathways hypothesized to mediate the alcohol-breast cancer association including hormonal, one-carbon metabolism, and oxidative stress pathways, but they could also affect risk via alternative pathways. Independent replication of alcohol-metabolite associations and prospective evaluation of confirmed associations with breast cancer risk are needed.

Dietary intakes and biomarker patterns of folate, vitamin B6, and vitamin B12 can be associated with cognitive impairment by hypermethylation of redox-related genes NUDT15 and TXNRD1

BackgroundB vitamins in the one-carbon metabolism pathway (folate, vitamin B6, and vitamin B12) have been implicated in DNA methylation, and their deficiency may contribute to cognitive decline through increased homocysteine (Hcy) levels and subsequent oxidative damage. The aim of this study was to investigate whether B vitamin deficiency and increased Hcy could interact with DNA methylation of oxidative-related genes and exacerbate cognitive impairment.MethodsParticipants were selected from a large cohort study entitled the Effects and Mechanism Investigation of Cholesterol and Oxysterol on Alzheimer’s disease (EMCOA) study. We included 2533 participants who completed a selection of comprehensive cognitive tests and a semiquantitative food frequency questionnaire (FFQ) and were followed for an average of 2.3 years. The longitudinal effects of B vitamin intake on cognitive decline were examined using linear mixed-effect models. Seven mild cognitive impairment (MCI) patients, in the predementia stage of Alzheimer’s disease (AD), and fivev healthy controls were selected for the discovery of genome-wide differentially methylated CpG sites. Candidate oxidative stress-related genes significantly correlated with serum levels of B vitamins were selected for validation in 102 MCI patients and 68 controls. The correlations between DNA methylation levels and serum concentrations of B vitamins and oxidative biomarkers were analyzed with Spearman’s correlation. The interactive effects of DNA methylation and B vitamins on cognitive performance were further evaluated by multiple linear regression.ResultsIn the prospective analysis, inadequate dietary intake of vitamin B12 was significantly associated with accelerated cognitive decline, whereas adequate folate, vitamin B6, and vitamin B12 intakes were significantly associated with better cognitive reserve. In the case-control analysis, the DNA methylation levels of NUDT15 and TXNRD1 were examined, and significantly hypermethylated sites were identified in MCI patients. Significant correlations of hypermethylated sites with serum levels of folate, homocysteine (Hcy), and oxidative biomarkers were observed, and interactive effects of B vitamins and hypermethylated sites were significantly associated with cognitive performance.ConclusionAdequate dietary folate at baseline predicted a better cognitive reserve, while decreased serum levels of B vitamins may contribute to cognitive impairment by affecting methylation levels of specific redox-related genes.Trial registrationEMCOA, ChiCTR-OOC-17011882, Registered 5th, July 2017-Retrospectively registered, http://www.medresman.org/uc/project/projectedit.aspx?proj=2610Graphical

Metabolomics analysis of children with autism, idiopathic-developmental delays, and Down syndrome

Although developmental delays affect learning, language, and behavior, some evidence suggests the presence of disturbances in metabolism are associated with psychiatric disorders. Here, the plasma metabolic phenotype of children with autism spectrum disorder (ASD, n = 167), idiopathic-developmental delay (i-DD, n = 51), and Down syndrome (DS, n = 31), as compared to typically developed (TD, n = 193) controls was investigated in a subset of children from the case–control Childhood Autism Risk from Genetics and the Environment (CHARGE) Study. Metabolome profiles were obtained using nuclear magnetic resonance spectroscopy and analyzed in an untargeted manner. Forty-nine metabolites were identified and quantified in each sample that included amino acids, organic acids, sugars, and other compounds. Multiple linear regression analysis revealed significant associations between 11 plasma metabolites and neurodevelopmental outcome. Despite the varied origins of these developmental disabilities, we observed similar perturbation in one-carbon metabolism pathways among DS and ASD cases. Similarities were also observed in the DS and i-DD cases in the energy-related tricarboxylic acid cycle. Other metabolites and pathways were uniquely associated with DS or ASD. By comparing metabolic signatures between these conditions, the current study expands on extant literature demonstrating metabolic alterations associated with developmental disabilities and provides a better understanding of overlapping vs specific biological perturbations associated with these disorders.

1880PD - Genetic variants in the one-carbon metabolism pathway to predict outcome in patients with metastatic colorectal cancer (mCRC): Data from TRIBE and FIRE-3 phase III trials

1880PD - Genetic variants in the one-carbon metabolism pathway to predict outcome in patients with metastatic colorectal cancer (mCRC): Data from TRIBE and FIRE-3 phase III trials

A novel nutritional supplement to reduce plasma homocysteine in nonpregnant women: A randomised controlled trial in The Gambia.

BackgroundInfant DNA methylation profiles are associated with their mother’s periconceptional nutritional status. DNA methylation relies on nutritional inputs for one-carbon metabolic pathways, including the efficient recycling of homocysteine. This randomised controlled trial in nonpregnant women in rural Gambia tests the efficacy of a novel nutritional supplement designed to improve one-carbon-related nutrient status by reducing plasma homocysteine, and assesses its potential future use in preconception trials.Methods and findingsWe designed a novel drink powder based on determinants of plasma homocysteine in the target population and tested it in a three-arm, randomised, controlled trial. Nonpregnant women aged between 18 and 45 from the West Kiang region of The Gambia were randomised in a 1:1:1 allocation to 12 weeks daily supplementation of either (a) a novel drink powder (4 g betaine, 800 μg folic acid, 5.2 μg vitamin B12, and 2.8 mg vitamin B2), (b) a widely used multiple micronutrient tablet (United Nations Multiple Micronutrient Preparation [UNIMMAP]) containing 15 micronutrients, or (c) no intervention. The trial was conducted between March and July 2018. Supplementation was observed daily. Fasted venepuncture samples were collected at baseline, midline (week 5), and endline (week 12) to measure plasma homocysteine. We used linear regression models to determine the difference in homocysteine between pairs of trial arms at midline and endline, adjusted for baseline homocysteine, age, and body mass index (BMI). Blood pressure and pulse were measured as secondary outcomes. Two hundred and ninety-eight eligible women were enrolled and randomised. Compliance was >97.8% for both interventions. At endline (our primary endpoint), the drink powder and UNIMMAP reduced mean plasma homocysteine by 23.6% (−29.5 to −17.1) and 15.5% (−21.2 to −9.4), respectively (both p < 0.001), compared with the controls. Compared with UNIMMAP, the drink powder reduced mean homocysteine by 8.8% (−15.8 to −1.2; p = 0.025). The effects were stronger at midline. There was no effect of either intervention on blood pressure or pulse compared with the control at endline. Self-reported adverse events (AEs) were similar in both intervention arms. There were two serious AEs reported over the trial duration, both in the drink powder arm, but judged to be unrelated to the intervention. Limitations of the study include the use of a single targeted metabolic outcome, homocysteine.ConclusionsThe trial confirms that dietary supplements can influence metabolic pathways that we have shown in previous studies to predict offspring DNA methylation. Both supplements reduced homocysteine effectively and remain potential candidates for future epigenetic trials in pregnancy in rural Gambia.Trial registrationClinicaltrials.gov Reference NCT03431597.

METHIONINE SYNTHASE1 Is Involved in Chromatin Silencing by Maintaining DNA and Histone Methylation.

DNA methylation and histone modification are important epigenetic marks that coregulate gene expression and genome stability. To identify factors involved in chromatin silencing, we carried out a forward genetic screen for mutants that release the silenced Pro-35S:LUCIFERASE (35SP-LUC) in Arabidopsis (Arabidopsis thaliana). We identified an epigenetic regulator, METHIONINE SYNTHASE1 (ATMS1), which catalyzes the synthesis of methionine (Met) in the one-carbon metabolism pathway. The ATMS1 mutation releases the silenced 35SP-LUC and the majority of endogenous genes and transposons. The effect of ATMS1 on chromatin silencing is related to decreased levels of DNA methylation (CG, CHG, and CHH) and histone-3 lysine-9 dimethylation. The ATMS1 mutation caused a significant decrease in the ratio of S-adenosylmethionine to S-adenosylhomocysteine. Exogenous application of Met rescued the phenotype of atms1-1 ATMS1 plays a predominant role in DNA and histone methylations among the three Met synthetase homologs. These results suggest that ATMS1 is required for DNA and histone methylations through its function in the one-carbon metabolism pathway, indicating the complex interplay between metabolism and epigenetic regulation.