Role In One-carbon Metabolism Research Articles

The Role of One-Carbon Metabolism and Methyl Donors in Medically Assisted Reproduction: A Narrative Review of the Literature.

One-carbon (1-C) metabolic deficiency impairs homeostasis, driving disease development, including infertility. It is of importance to summarize the current evidence regarding the clinical utility of 1-C metabolism-related biomolecules and methyl donors, namely, folate, betaine, choline, vitamin B12, homocysteine (Hcy), and zinc, as potential biomarkers, dietary supplements, and culture media supplements in the context of medically assisted reproduction (MAR). A narrative review of the literature was conducted in the PubMed/Medline database. Diet, ageing, and the endocrine milieu of individuals affect both 1-C metabolism and fertility status. In vitro fertilization (IVF) techniques, and culture conditions in particular, have a direct impact on 1-C metabolic activity in gametes and embryos. Critical analysis indicated that zinc supplementation in cryopreservation media may be a promising approach to reducing oxidative damage, while female serum homocysteine levels may be employed as a possible biomarker for predicting IVF outcomes. Nonetheless, the level of evidence is low, and future studies are needed to verify these data. One-carbon metabolism-related processes, including redox defense and epigenetic regulation, may be compromised in IVF-derived embryos. The study of 1-C metabolism may lead the way towards improving MAR efficiency and safety and ensuring the lifelong health of MAR infants.

A new mathematical model of folate homeostasis in E. coli highlights the potential importance of the folinic acid futile cycle in cell growth

Folate (vitamin B9) plays a central role in one-carbon metabolism in prokaryotes and eukaryotes. This pathway mediates the transfer of one-carbon units, playing a crucial role in nucleotide synthesis, methylation, and amino acid homeostasis. The folinic acid futile cycle adds a layer of intrigue to this pathway, due to its associations with metabolism, cell growth, and dormancy. It also introduces additional complexity to folate metabolism. A logical way to deal with such complexity is to examine it by using mathematical modelling. This work describes the construction and analysis of a model of folate metabolism, which includes the folinic acid futile cycle. This model was tested under three in silico growth conditions. Model simulations revealed: 1) the folate cycle behaved as a stable biochemical system in three growth states (slow, standard, and rapid); 2) the initial concentration of serine had the greatest impact on metabolite concentrations; 3) 5-formyltetrahydrofolate cyclo-ligase (5-FCL) activity had a significant impact on the levels of the 7 products that carry the one-carbon donated from folates, and the redox couple NADP/NADPH; this was particularly evident in the rapid growth state; 4) 5-FCL may be vital to the survival of the cells by maintaining low levels of homocysteine, as high levels can induce toxicity; and 5) the antifolate therapeutic trimethoprim had a greater impact on folate metabolism with higher nutrient availability. These results highlight the important role of 5-FCL in intracellular folate homeostasis and mass generation under different metabolic scenarios.

Vitamin B12 is a limiting factor for induced cellular plasticity and tissue repair

Transient reprogramming by the expression of OCT4, SOX2, KLF4 and MYC (OSKM) is a therapeutic strategy for tissue regeneration and rejuvenation, but little is known about its metabolic requirements. Here we show that OSKM reprogramming in mice causes a global depletion of vitamin B12 and molecular hallmarks of methionine starvation. Supplementation with vitamin B12 increases the efficiency of reprogramming both in mice and in cultured cells, the latter indicating a cell-intrinsic effect. We show that the epigenetic mark H3K36me3, which prevents illegitimate initiation of transcription outside promoters (cryptic transcription), is sensitive to vitamin B12 levels, providing evidence for a link between B12 levels, H3K36 methylation, transcriptional fidelity and efficient reprogramming. Vitamin B12 supplementation also accelerates tissue repair in a model of ulcerative colitis. We conclude that vitamin B12, through its key role in one-carbon metabolism and epigenetic dynamics, improves the efficiency of in vivo reprogramming and tissue repair.

The major role of Listeria monocytogenes folic acid metabolism during infection is the generation of N-formylmethionine.

Folic acid is an essential vitamin for bacteria, plants, and animals. The lack of folic acid leads to various consequences such as a shortage of amino acids and nucleotides that are fundamental building blocks for life. Though antifolate drugs are widely used for antimicrobial treatments, the underlying mechanism of bacterial folate deficiency during infection is unclear. This study compares the requirements of different folic acid end-products during the infection of Listeria monocytogenes, a facultative intracellular pathogen of animals and humans. The results reveal the critical importance of N-formylmethionine, the amino acid used by bacteria to initiate protein synthesis. This work extends the current understanding of folic acid metabolism in pathogens and potentially provides new insights into antifolate drug development in the future.

The Role of One-Carbon Metabolism in Healthy Brain Aging.

Aging results in more health challenges, including neurodegeneration. Healthy aging is possible through nutrition as well as other lifestyle changes. One-carbon (1C) metabolism is a key metabolic network that integrates nutritional signals with several processes in the human body. Dietary supplementation of 1C components, such as folic acid, vitamin B12, and choline are reported to have beneficial effects on normal and diseased brain function. The aim of this review is to summarize the current clinical studies investigating dietary supplementation of 1C, specifically folic acid, choline, and vitamin B12, and its effects on healthy aging. Preclinical studies using model systems have been included to discuss supplementation mechanisms of action. This article will also discuss future steps to consider for supplementation. Dietary supplementation of folic acid, vitamin B12, or choline has positive effects on normal and diseased brain function. Considerations for dietary supplementation to promote healthy aging include using precision medicine for individualized plans, avoiding over-supplementation, and combining therapies.

Association between folate and non-alcoholic fatty liver disease among US adults: a nationwide cross-sectional analysis.

Association between folate and non-alcoholic fatty liver disease among US adults: a nationwide cross-sectional analysis.

One-carbon metabolism and related pathways in ruminal and small intestinal epithelium of lactating dairy cows.

Physiological and environmental stresses such as the transition into lactation and heat load contribute to gastrointestinal tract (GIT) dysfunction. The nonruminant gastrointestinal tract has mechanisms to cope with pro-oxidant and pro-inflammatory stressors arising from the gut lumen or within intestinal cells. One-carbon metabolism (OCM) contributes to anti-oxidant capacity via the production of glutathione (GSH) and taurine, and the synthesis of phospholipid, creatine, and the osmolyte glycinebetaine among others. A multipronged approach was used to assess the biological relevance of OCM and closely-related pathways on GIT function in dairy cows. Ruminal papillae (Rum) and scrapings from duodenum (Duo), jejunum (Jej), and ileum (Ile) were collected at slaughter from eight multiparous Holstein cows averaging 128 ± 12 d in milk and producing 39 ± 5 kg/d. A MIXED model ANOVA with preplanned orthogonal contrasts was used for statistical analysis. Methionine adenosyl transferase 1 activity (MAT) was ~10-fold greater (P < 0.01) and cystathionine β-synthase activity doubled in Rum vs. small intestine. Total glutathione peroxidase (GPX) activity was greatest (P = 0.03) in Ile, but similar to Rum. Activity and mRNA abundance of betaine-homocysteine S-methyltransferase were undetectable. There was a 2.5-fold greater protein abundance of GPX1 (P < 0.01) and a ~2-fold greater abundance of GPX3 (P < 0.01) in Rum vs. small intestine. Among the various amino acids (AA) with roles in OCM or closely-related pathways (e.g. creatine synthesis), concentrations of arginine, aspartate, glutamine, methionine, and serine were lower (P < 0.01) in Rum vs. small intestine. Unlike AA, concentrations of OCM-related intermediates S-5'-adenosyl-homocysteine (SAH), glycinebetaine, carnitine, creatine (CRE), and cysteinesulfinic acid were greater (P < 0.01) while taurine was lower in Rum vs. small intestine. Intermediates of the folate cycle were undetectable. The fact that S-adenosylmethionine (SAM) was undetectable while MAT activity and SAH were greater in Rum suggested that availability of SAM (a methyl donor) is a key determinant of flux through the folate and methionine cycles in the GIT. Except for adenosine, concentrations of glutamate, glycine, α-ketoglutarate, hypotaurine, and GSH were lowest in Ile. Together, the data underscored unique differences in activity of one-carbon metabolism and related pathways across sections of the GIT.

Proteomic, Transcriptomic, Mutational, and Functional Assays Reveal the Involvement of Both THF and PLP Sites at the GmSHMT08 in Resistance to Soybean Cyst Nematode.

The serine hydroxymethyltransferase (SHMT; E.C. 2.1.2.1) is involved in the interconversion of serine/glycine and tetrahydrofolate (THF)/5,10-methylene THF, playing a key role in one-carbon metabolism, the de novo purine pathway, cellular methylation reactions, redox homeostasis maintenance, and methionine and thymidylate synthesis. GmSHMT08 is the soybean gene underlying soybean cyst nematode (SCN) resistance at the Rhg4 locus. GmSHMT08 protein contains four tetrahydrofolate (THF) cofactor binding sites (L129, L135, F284, N374) and six pyridoxal phosphate (PLP) cofactor binding/catalysis sites (Y59, G106, G107, H134, S190A, H218). In the current study, proteomic analysis of a data set of protein complex immunoprecipitated using GmSHMT08 antibodies under SCN infected soybean roots reveals the presence of enriched pathways that mainly use glycine/serine as a substrate (glyoxylate cycle, redox homeostasis, glycolysis, and heme biosynthesis). Root and leaf transcriptomic analysis of differentially expressed genes under SCN infection supported the proteomic data, pointing directly to the involvement of the interconversion reaction carried out by the serine hydroxymethyltransferase enzyme. Direct site mutagenesis revealed that all mutated THF and PLP sites at the GmSHMT08 resulted in increased SCN resistance. We have shown the involvement of PLP sites in SCN resistance. Specially, the effect of the two Y59 and S190 PLP sites was more drastic than the tested THF sites. This unprecedented finding will help us to identify the biological outcomes of THF and PLP residues at the GmSHMT08 and to understand SCN resistance mechanisms.

No Association Between Riboflavin and Choline Status in a Sample of Canadian and Malaysian Women of Reproductive Age

ObjectivesRiboflavin and choline are essential nutrients that are metabolically inter-related and play major roles in one-carbon metabolism. Betaine can donate a methyl group to homocysteine, forming dimethylglycine (DMG) and methionine in the liver and kidney. Betaine is synthesized from choline in two irreversible reactions, the first of which is catalyzed by flavin adenine dinucleotide (FAD), a cofactor formed from riboflavin. In animal models, riboflavin status has been shown to influence choline and its metabolites betaine and DMG but there are no human studies. Here we examine whether riboflavin status modifies plasma choline, betaine, and DMG concentrations in healthy women (19–45 y).MethodsFasting blood was collected from 206 Canadian and 210 Malaysian women between 2015 and 2016. Riboflavin status was assessed using a functional biomarker, erythrocyte glutathione reductase activity coefficient (EGRac). Plasma choline, betaine, and DMG were determined by LCLC MS/MS. Plasma folate and vitamin B12 were determined using the microbiological method and an immune assay, respectively. General linear models were used to assess the independent relationship between EGRac and each of the choline metabolites with adjustment for potential confounders.Results71% of Malaysian women had EGRac ≥1.40 compared to 40% of Canadian women. Betaine, DMG, and vitamin B12 concentrations were significantly higher among Malaysian women compared to Canadian women (40.6 vs. 37.0 mmol/L, 2.7 vs. 2.4 mmol/L and 360 vs. 307 pmol/L, respectively). There were no significant associations between EGRac or riboflavin deficiency (defined as EGRac ≥1.40) and choline or its’ metabolites after adjustments for age, ethnicity, body mass index, plasma folate, and vitamin B12. In the adjusted models, plasma choline was positively associated with vitamin B12 concentrations (B = 0.002, 95% CI: 0.000, 0.003) and plasma betaine was positively associated with plasma folate (B = 0.18, 95%CI: 0.07, 0.29) and vitamin B12 (B = 0.011, 95%CI: 0.002, 0.020).ConclusionsOverall, riboflavin status was not associated with choline and its metabolites in Canadian and Malaysian women.Funding SourcesDairy Farmers of Canada, Saudi Arabian Cultural Bureau in Canada, and BC Children's Hospital Research Institute.

Folic acid deficiency increases sensitivity to DNA damage by glucose and methylglyoxal.

Type 2 diabetes (T2D) is associated with elevated frequencies of micronuclei (MNi) and other DNA damage biomarkers. Interestingly, individuals with T2D are more likely to be deficient in micronutrients (folic acid, pyridoxal-phosphate, cobalamin) that play key roles in one-carbon metabolism and maintaining genomic integrity. Furthermore, it has recently been shown that deficiencies in these nutrients, in particular folic acid leaves cells susceptible to glucose-induced DNA damage. Therefore, we sought to investigate if the B lymphoblastoid WIL2-NS cell line cultured under folic acid-deficient conditions was more sensitive to DNA damage induced by glucose, or the reactive glycolytic byproduct methylglyoxal (MGO) and subsequent advanced glycation endproduct formation. Here, we show that only WIL2-NS cultured under folic acid-deficient conditions (23 nmol/l) experience an increase in MNi frequency when exposed to high concentrations of glucose (45 mmol/l) or MGO (100 µmol/l). Furthermore, we showed aminoguanidine, a well-validated MGO and free radical scavenger was able to prevent further MNi formation in folic acid-deficient cells exposed to high glucose, which may be due to a reduction in MGO-induced oxidative stress. Interestingly, we also observed an increase in MGO and other dicarbonyl stress biomarkers in folic acid-deficient cells, irrespective of glucose concentrations. Overall, our evidence shows that folic acid-deficient WIL2-NS cells are more susceptible to glucose and/or MGO-induced MNi formation. These results suggest that individuals with T2D experiencing hyperglycemia and folic acid deficiency may be at higher risk of chromosomal instability.

Dietary Intake Adequacy and Food Sources of Nutrients Involved in the Methionine-Methylation Cycle in Women of Childbearing Age from the ANIBES Spanish Population.

Growing evidence confirms choline as a critical perinatal nutrient. However, intake levels of choline and betaine among the Spanish fertile population remain unknown. Given their role in one-carbon metabolism with potential epigenetic effects, the aim of the present study was to evaluate the dietary intakes, their adequacy to existing guidelines and the main food sources together with other micronutrients involved in the methylation-methionine cycle (vitamin B6, folates and vitamin B12) in women of childbearing age. The ANIBES study, a cross-sectional study of a representative sample of women of childbearing age (18–45 years, n = 641) resident in Spain, was used. The sample was divided into younger women (18–30 years, n = 251) and older women (31–45 years, n = 390). Dietary intake was assessed by a three-day dietary record by using a tablet device. Total median intakes for the total sample were 303.9 mg/d for choline; 122.6 mg/d for betaine; 1.3 mg/d for vitamin B6; 140.8 μg/d for folates, and 3.8 μg/d for vitamin B12. The older subgroup showed significantly higher choline (p < 0.05), betaine (p < 0.001) and folates (p < 0.05) intakes than younger women. Main food sources for the whole sample were meat and meat products for choline (28.3%), vitamin B6 (25.7%) and vitamin B12 (22.8%); cereals and derivatives (79.9%) for betaine; vegetables (20.0%) for folates. Overall intake adequacy was only observed for vitamin B12, with a very limited number of participants showing adequate intakes for all the other micronutrients. These results illustrate there is a relevant need to raise awareness about optimizing the status of the methionine cycle-related vitamins and cofactors in this potentially vulnerable population.

Xanthine Derivatives Reveal an Allosteric Binding Site in Methylenetetrahydrofolate Dehydrogenase 2 (MTHFD2).

Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) plays an important role in one-carbon metabolism. The MTHFD2 gene is upregulated in various cancers but very low or undetectable in normal proliferating cells, and therefore a potential target for cancer treatment. In this study, we present the structure of MTHFD2 in complex with xanthine derivative 15, which allosterically binds to MTHFD2 and coexists with the substrate analogue. A kinetic study demonstrated the uncompetitive inhibition of MTHFD2 by 15. Allosteric inhibitors often provide good selectivity and, indeed, xanthine derivatives are highly selective for MTHFD2. Moreover, several conformational changes were observed upon the binding of 15, which impeded the binding of the cofactor and phosphate to MTHFD2. To the best of our knowledge, this is the first study to identify allosteric inhibitors targeting the MTHFD family and our results would provide insights on the inhibition mechanism of MTHFD proteins and the development of novel inhibitors.

Riboflavin intake, MTRR genetic polymorphism (rs1532268) and gastric cancer risk in a Korean population: a case-control study.

The vitamin B group, including riboflavin, plays paramount roles in one-carbon metabolism (OCM), and disorders related to this pathway have been linked to cancer development. The variants of genes encoding OCM enzymes and the insufficiency of B vitamins could contribute to carcinogenesis. Very few observational studies have revealed a relationship between riboflavin and gastric cancer (GC), especially under conditions of modified genetic factors. We carried out a study examining the association of riboflavin intake and its interaction with MTRR (rs1532268) genetic variants with GC risk among 756 controls and 377 cases. The OR and 95 % CI were evaluated using unconditional logistic regression models. We observed protective effects of riboflavin intake against GC, particularly in the female subgroup (OR = 0·52, 95 % CI 0·28, 0·97, Ptrend = 0·031). In the MTRR (rs1532268) genotypes analysis, the dominant model showed that the effects of riboflavin differed between the CC and CT + TT genotypes. Compared with CC carriers, low riboflavin intake in T+ carriers was significantly associated with a 93 % higher GC risk (OR = 1·93, 95 % CI 1·09, 3·42, Pinteraction = 0·037). In general, higher riboflavin intake might help reduce the risk of GC in both CC and TC + TT carriers, particularly the T+ carriers, with marginal significance (OR = 0·54, 95 % CI 0·28, 1·02, Pinteraction = 0·037). Our study indicates a protective effect of riboflavin intake against GC. Those who carry at least one minor allele and have low riboflavin intake could modify this association to increase GC risk in the Korean population.

Dietary Methyl-Group Donor Intake and Breast Cancer Risk in the European Prospective Investigation into Cancer and Nutrition (EPIC).

(1) Background: Methyl-group donors (MGDs), including folate, choline, betaine, and methionine, may influence breast cancer (BC) risk through their role in one-carbon metabolism; (2) Methods: We studied the relationship between dietary intakes of MGDs and BC risk, adopting data from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort; (3) Results: 318,686 pre- and postmenopausal women were followed between enrolment in 1992–2000 and December 2013–December 2015. Dietary MGD intakes were estimated at baseline through food-frequency questionnaires. Multivariable Cox proportional hazards regression models were used to quantify the association between dietary intake of MGDs, measured both as a calculated score based on their sum and individually, and BC risk. Subgroup analyses were performed by hormone receptor status, menopausal status, and level of alcohol intake. During a mean follow-up time of 14.1 years, 13,320 women with malignant BC were identified. No associations were found between dietary intakes of the MGD score or individual MGDs and BC risk. However, a potential U-shaped relationship was observed between dietary folate intake and overall BC risk, suggesting an inverse association for intakes up to 350 µg/day compared to a reference intake of 205 µg/day. No statistically significant differences in the associations were observed by hormone receptor status, menopausal status, or level of alcohol intake; (4) Conclusions: There was no strong evidence for an association between MGDs involved in one-carbon metabolism and BC risk. However, a potential U-shaped trend was suggested for dietary folate intake and BC risk. Further research is needed to clarify this association.

One carbon (metabolism) to rule T cell identity.

A preprint by Sugiura et al. looks at the role of one-carbon metabolism during T cell activation, with a focus on autoimmune disease, and identifies differences between T cell subsets.

Associations between Plasma Choline Metabolites and Genetic Polymorphisms in One-Carbon Metabolism in Postmenopausal Women: The Women's Health Initiative Observational Study

Background:Choline plays an integral role in one-carbon metabolism in the body, but it is unclear whether genetic polymorphisms are associated with variations in plasma choline and its metabolites. Objectives:This study aimed to evaluate the association of genetic variants in choline and one-carbon metabolism with plasma choline and its metabolites. Methods:We analyzed data from 1423 postmenopausal women in a case-control study nested within the Women's Health Initiative Observational Study. Plasma concentrations of choline, betaine, dimethylglycine (DMG), and trimethylamine N-oxide were determined in 12-h fasting blood samples collected at baseline (1993–1998). Candidate and tagging single-nucleotide polymorphisms (SNPs) were genotyped in betaine-homocysteine S-methyltransferase (BHMT), BHMT2, 5,10-methylenetetrahydrofolate reductase (MTHFR), methylenetetrahydrofolate dehydrogenase (NADP+ dependent 1) (MTHFD1), 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), and 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR). Linear regression was used to derive percentage difference in plasma concentrations per variant allele, adjusting for confounders, including B-vitamin biomarkers. Potential effect modification by plasma vitamin B-12, vitamin B-6, and folate concentrations and folic-acid fortification periods was examined. ResultsThe candidate SNP BHMT R239Q (rs3733890) was associated with lower concentrations of plasma betaine and DMG concentrations (–4.00% and –6.75% per variant allele, respectively; both nominal P < 0.05). Another candidate SNP, BHMT2 rs626105 A>G, was associated with higher plasma DMG concentration (13.0%; P < 0.0001). Several tagSNPs in these 2 genes were associated with plasma concentrations after correction for multiple comparisons. Vitamin B-12 status was a significant effect modifier of the association between the genetic variant BHMT2 rs626105 A>G and plasma DMG concentration. ConclusionsGenetic variations in metabolic enzymes were associated with plasma concentrations of choline and its metabolites. Our findings contribute to the knowledge on the variation in blood nutrient concentrations in postmenopausal women.

Detectable Unmetabolized Folic Acid, and Sufficient Folate and Vitamin B12 Concentrations Are Evident in Canadian Children with Sickle Cell Disease

Abstract Objectives Canadian children with sickle cell disease (SCD) are routinely supplemented with high-dose folic acid (1 mg/d), synthetic folate, due to increased erythrocyte production and turn-over in the disease. Folate also plays a vital role in one-carbon metabolism. Impairments in this folate-dependent mechanism can also occur due to secondary B-vitamin (vitamin B2, B6 and B12) deficiencies. The study objective was to determine B-vitamin status in Canadian children with SCD. Methods Serum and plasma samples from children diagnosed with SCD were obtained from BC Children's Hospital BioBank (Vancouver, Canada). Samples were analyzed for folate, vitamin B6, and related metabolites using electrospray ionization-liquid chromatography-tandem mass spectrometry. Vitamin B12 concentrations were analyzed using chemiluminescent immunoassay. World Health Organization cut-offs were used to determine deficiencies of folate (&amp;lt;10 nmol/L) and vitamin B12 (&amp;lt;150 pmol/L), and European Food Safety Authority Panel cut-offs were used for vitamin B6 (&amp;lt;30 nmol/L pyridoxal 5’-phosphate; PLP). Medians with interquartile ranges (IQR) are presented. Results Six individuals (50% male; SCD type: Hgb SS n = 3, Hgb SC n = 2, HbSβ,0-Thal n = 1) were included. Median age of participants was 15 (9, 18) years. Half (50%) of participants were prescribed hydroxyurea (median dose: 21(14, 30) mg/kg/d), and all participants were prescribed 1 mg/d folic acid (adherence data not available). Median serum folate was 55.4 (43.1, 71.9) nmol/L, with levels 3 to 15 times above the cut-off for deficiency. Unmetabolized folic acid (UMFA), unused folic acid in circulation, was detected in all six participants. All participants were vitamin B12 sufficient, with median plasma vitamin B12 of 325 (288, 411) nmol/L. The majority (n = 5; 83%) had sufficient B6 status, with median serum PLP of 39 (36.9, 44.2) nmol/L. Conclusions In this pilot project, there was limited evidence of B-vitamin deficiencies among Canadian children with SCD. Serum folate levels exceeded the cut-off for deficiency by 3 to 15 times, with all participants having detectable levels of UMFA. A randomized clinical trial re-assessing the routine practice of high-dose folic acid supplementation in children with SCD is warranted. Funding Sources Thrasher Research Fund and Rare Disease Foundation.

The Role of One-Carbon Metabolism After Ischemic Stroke in an Aged Mouse Model

Abstract Objectives Nutrition is a modifiable risk factor for stroke, which is one of the leading causes of death and disability world-wide. In humans deficiencies in one-carbon metabolism, including the methyltetrahydrofolate reductase (MTHFR) polymorphism, have been linked to increased risk of stroke. The Mthfr+/− mice mouse model mimics the phenotype of the MTHFR677C – &amp;gt;T polymorphism. In our work using in vitro and in vivo models of ischemic stroke we have observed decreased recovery after stroke through reduced neuronal and astrocyte viability and increased apoptosis in MTHFR-deficient mice. In addition, we have previously shown dietary supplementation of one-carbon metabolites increases neuroplasticity and reduced oxidative stress after ischemic stroke. Using the MTHFR-deficient mouse model, the aim of this study was to investigate the impact of dietary supplementation with one-carbon metabolites on stroke outcome. Methods Male Mthfr+/− and wildtype littermate control mice were aged to 1.5-year-old and were placed on control diet (CD) 4-weeks prior to sensorimotor cortex damage using photothrombosis (PT), a model for ischemic stroke. Post-operatively, one group of Mthfr+/− and wildtype littermate mice were fed a supplemented diet (SD) containing 5-methylTHF, vitamin B12, and choline. Four weeks after PT damage and SD motor function was assessed and brain tissue was processed to assess lesion volume and investigate biochemical and molecular changes. Results Mthfr +/− mice fed a SD after PT did not have an impaired neuroscore compared to CD Mthfr+/− mice. When compared to CD, SD Mthfr+/− mice were able to stay on the accelerating rotarod longer and travelled further, they also used their impaired forepaw more. Total homocysteine levels in plasma and lesion volume were reduced in SD Mthfr+/+ and Mthfr+/− mice. In the brain, within the damage site, there were reduced levels of apoptotic cell death and an increased neuroprotective cellular response in SD treated Mthfr+/− mice. Conclusions This study reveals a critical role for one-carbon supplementation in supporting improvement of function after ischemic stroke. Our data suggests that in stroke affected patients, nutritional supplementation maybe an important component to post-operative care, in addition to pharmacological and rehabilitation therapies. Funding Sources NSERC.

Amino Acid Status in Pregnancy: Urinary Catabolites As Non-Invasive Biomarkers

Abstract Objectives Pregnancy is a metabolically active life stage. Formate plays a major role in one-carbon metabolism, a biosynthetic pathway critical for cellular growth and function. Because formate can be synthesized from amino acid precursors serine, glycine, tryptophan and methionine, it suggests that urinary formate concentration may be low in response to low protein intakes. Additionally, sulfate is the excretory endpoint for the breakdown of indispensable, sulfur containing amino acids methionine and cysteine. Our objectives were to determine if urinary excretion of formate/sulfate can be utilized as non-invasive biomarkers in pregnancy, when protein intakes range from deficient to adequate. Methods Urinary samples (n = 81) from pregnant women (11–20- and 30–38-weeks’ gestation) were collected when consuming graded protein intakes (0.2–2.56 g/kg/d) and were analyzed for sulfate and formate concentrations. For sulfate, spectrophotometric absorbance was measured and compared to a standard curve, and formate was analyzed using an enzymatic assay. Concentrations of the catabolites were normalized using creatinine concentrations and plotted against protein intakes. Regression models were used to examine potential relationships. Sulfate excretion was also compared to the estimated total sulfur amino acid intake (TSAA, methionine + cysteine). Results With increasing protein intakes, formate excretion remained constant. Urinary sulfate concentrations increased in response to increasing protein. A bi-phase linear regression model revealed there was an observable breakpoint in increased sulfate excretion in early gestation at 33–36 mg/kg/d of estimated TSAA intake, and at 30–39 mg/kg/d for late gestation. Conclusions There was no observable relationship to suggest urinary formate could be used as a biomarker for protein/amino acid status during pregnancy. Urinary sulfate concentrations may be a viable indicator for measuring total sulfur amino acid (methionine, cysteine) status. Further studies on TSAA requirements in pregnancy using more state-of-the-art stable isotope techniques are needed to confirm these findings from non-invasive urinary biomarkers. Funding Sources Canadian Institutes of Health Research.

Folates: Stability and interaction with biological molecules

Folates play a key role in one-carbon metabolism and are beneficial in the prevention of neural tube defects, cardiovascular and neurodegenerative diseases. Fruits and vegetables, with high contents of folates, are mostly consumed after food processing. Hence, it is important to know the process of folate losses and the interaction between folate and co-solutes. The current knowledge on stability of folates in foods and interaction with biological molecules are presented in this review. Folates degrade under light, heat, oxygen, and acidic pH. Antioxidants allow better preservation of folates. Folates bind to proteins and alter protein structure under irradiation, while proteins improve the photostability of folates. Folates interact with nucleotides and induce DNA damage under irradiation. Reactions of folates with other food components such as reducing sugars, especially that fructose and glucose accelerate the degradation of folates. Additionally, future perspectives in this context are identified. Note: this figure was adapted from references [51, 67], with permission from Elsevier, and from references [16, 49], with permission from ACS. • The structures and properties of folates were introduced. • Stability of folates under several parameters was discussed. • Interaction with other biomolecules was summarized.