The Differential Translation Capabilities of the Human DHFR2 Gene Indicates a Developmental and Tissue-Specific Endogenous Protein of Low Abundance.

A functional role has been ascribed to the human dihydrofolate reductase 2 (DHFR2) gene based on the enzymatic activity of recombinant versions of the predicted translated protein. However, the in vivo function is still unclear. The high amino acid sequence identity (92%) between DHFR2 and its parental homolog, DHFR, makes analysis of the endogenous protein challenging. This paper describes a targeted mass spectrometry proteomics approach in several human cell lines and tissue types to identify DHFR2-specific peptides as evidence of its translation. We show definitive evidence that the DHFR2 activity in the mitochondria is in fact mediated by DHFR, and not DHFR2. Analysis of Ribo-seq data and an experimental assessment of ribosome association using a sucrose cushion showed that the two main Ensembl annotated mRNA isoforms of DHFR2, 201 and 202, are differentially associated with the ribosome. This indicates a functional role at both the RNA and protein level. However, we were unable to detect DHFR2 protein at a detectable level in most cell types examined despite various RNA isoforms of DHFR2 being relatively abundant. We did detect a DHFR2-specific peptide in embryonic heart, indicating that the protein may have a specific role during embryogenesis. We propose that the main functionality of the DHFR2 gene in adult cells is likely to arise at the RNA level.

Polyphenol intake and cardiovascular risk in the PREDIMED-Plus trial. A comparison of different risk equations.

INTRODUCTION AND OBJECTIVES: Quantification of cardiovascular risk has been based on scores such as Framingham, Framingham-REGICOR, SCORE or Life's Simple 7 (LS7). In vitro, animal, and randomized clinical studies have shown that polyphenols may provide benefits to the vascular system and reduce the inflammatory response. However, some clinical-epidemiological studies have yielded inconsistent results. Our aim was to assess the possible association between intake of the various polyphenol classes and established cardiovascular scores. METHODS: This cross-sectional analysis involved 6633 PREDIMED-Plus study participants. Food polyphenol content was estimated by a semiquantitative food frequency questionnaire, adjusted for total energy intake according to the residual method. The association between polyphenol intake and cardiovascular risk was tested using linear regression analyses. RESULTS: Total polyphenol and flavonoid intake were directly and significantly associated only with the LS7 scale. Intake of lignans was directly and significantly associated with SCORE and LS7 scales, stilbene intake with SCORE, and phenolic acid intake with Framingham and Framingham-REGICOR scores. Other polyphenol classes were associated in a protective and significant manner in Framingham, SCORE and LS7 scores. In women, intake of all the polyphenol classes, except phenolic acids, showed a protective trend in the results of the Framingham, Framingham-REGICOR scores and LS7 scale. CONCLUSIONS: An inverse association was found between consumption of the 'other polyphenols' class and, especially among women, with estimated cardiovascular risk. The results were similar to those of Framingham, Framingham-REGICOR and LS7 (after eliminating the diet component) and differed from those of SCORE, but the predictors included were limited in the latter case.

Moderately elevated first trimester fasting plasma total homocysteine is associated with increased probability of miscarriage. The Reus-Tarragona Birth Cohort Study.

The association between elevated early pregnancy fasting plasma total homocysteine (tHcy) and miscarriage risk was investigated prospectively in participants (n = 544) from the Reus-Tarragona Birth Cohort study. Pregnancy was confirmed before 12 gestational weeks (GW) by ultrasound scan and a fasting blood sample collected. Pregnancies with complications other than miscarriages were excluded. Miscarriages were diagnosed by ultrasound scan and gestational age at the time of miscarriage estimated by embryo size, where possible. Cases in which blood samples were collected more than a week after the miscarriage, or the miscarriage was of known cause, were excluded. Fasting plasma folate, vitamin B12, tHcy, cotinine (biomarker of smoking), red blood cell (RBC) folate, MTHFR 677C > T (rs1801133) and SLC19A1 80G>A (rs1051266) genotypes were determined. The exposed group consisted of participants with first trimester tHcy ≥ P90 (7.1 µmol/L) (n = 57) and unexposed of those with tHcy < P90 (n = 487). Adherence to folic acid supplement recommendations, plasma folate, plasma vitamin B12, RBC folate and prevalence of optimal RBC folate status (≥ 906 µmol/L) were lower in the exposed compared to unexposed group. The prevalences of the MTHFR 677 TT genotype and miscarriage were higher in the exposed group. The relative risks (95% CI) of pregnancy ending in miscarriage were 2.5 (1.1, 5.7) and 2.1 (1.0, 4.5) for participants in the high tHcy and suboptimal RBC folate groups (compared to the reference groups) respectively. Adherence to folic acid supplement recommendations was positively associated, while the MTHFR 677 TT versus CC genotype and smoking versus non-smoking were negatively associated, with RBC folate status.

Maternal Folate Status and the BHMT c.716G>A Polymorphism Affect the Betaine Dimethylglycine Pathway during Pregnancy.

The effect of the betaine: homocysteine methyltransferase BHMT c.716G>A (G: guanosine; A: adenosine) single nucleotide polymorphism (SNP) on the BHMT pathway is unknown during pregnancy. We hypothesised that it impairs betaine to dimethylglycine conversion and that folate status modifies its effect. We studied 612 women from the Reus Tarragona Birth Cohort from ≤12 gestational weeks (GW) throughout pregnancy. The frequency of the variant BHMT c.716A allele was 30.8% (95% confidence interval (CI): 28.3, 33.5). In participants with normal-high plasma folate status (>13.4 nmol/L), least square geometric mean [95% CI] plasma dimethylglycine (pDMG, µmol/L) was lower in the GA (2.35 [2.23, 2.47]) versus GG (2.58 [2.46, 2.70]) genotype at ≤12 GW (p < 0.05) and in the GA (2.08 [1.97, 2.19]) and AA (1.94 [1.75, 2.16]) versus GG (2.29 [2.18, 2.40]) genotypes at 15 GW (p < 0.05). No differences in pDMG between genotypes were observed in participants with possible folate deficiency (≤13.4 nmol/L) (p for interactions at ≤12 GW: 0.023 and 15 GW: 0.038). PDMG was lower in participants with the AA versus GG genotype at 34 GW (2.01 [1.79, 2.25] versus 2.44 [2.16, 2.76] and at labour, 2.51 [2.39, 2.64] versus 3.00 [2.84, 3.18], (p < 0.01)). Possible deficiency compared to normal-high folate status was associated with higher pDMG in multiple linear regression analysis (ß coefficients [SEM] ranging from 0.07 [0.04], p < 0.05 to 0.20 [0.04], p < 0.001 in models from early and mid-late pregnancy) and the AA compared to GG genotype was associated with lower pDMG (ß coefficients [SEM] ranging from -0.11 [0.06], p = 0.055 to -0.23 [0.06], p < 0.001). CONCLUSION: During pregnancy, the BHMT pathway is affected by folate status and by the variant BHMT c.716A allele.

Exposure to Folate Receptor Alpha Antibodies during Gestation and Weaning Leads to Severe Behavioral Deficits in Rats: A Pilot Study.

The central nervous system continues to develop during gestation and after birth, and folate is an essential nutrient in this process. Folate deficiency and folate receptor alpha autoantibodies (FRα-AuAb) have been associated with pregnancy-related complications and neurodevelopmental disorders. In this pilot study, we investigated the effect of exposure to FRα antibodies (Ab) during gestation (GST), the pre-weaning (PRW), and the post weaning (POW) periods on learning and behavior in adulthood in a rat model. In the open field test and novel object recognition task, which examine locomotor activity and anxiety-like behavior, deficits in rats exposed to Ab during gestation and pre-weaning (GST+PRW) included more time spent in the periphery or corner areas, less time in the central area, frequent self-grooming akin to stereotypy, and longer time to explore a novel object compared to a control group; these are all indicative of increased levels of anxiety. In the place avoidance tasks that assess learning and spatial memory formation, only 30% of GST+PRW rats were able to learn the passive place avoidance task. None of these rats learned the active place avoidance task indicating severe learning deficits and cognitive impairment. Similar but less severe deficits were observed in rats exposed to Ab during GST alone or only during the PRW period, suggesting the extreme sensitivity of the fetal as well as the neonatal rat brain to the deleterious effects of exposure to Ab during this period. Behavioral deficits were not seen in rats exposed to antibody post weaning. These observations have implications in the pathology of FRα-AuAb associated with neural tube defect pregnancy, preterm birth and neurodevelopmental disorders including autism.

Early pregnancy B vitamin status, one carbon metabolism, pregnancy outcome and child development.

Periconception supplementation with folic acid is recommended until 12 gestational weeks to prevent neural tube defects. Doses of folic acid contained in supplements and timing and length of use during pregnancy vary. The effects of status in periconception and pregnancy folate, cobalamin, betaine and their interactions on one carbon metabolism (1C), as well as the global effect of 1C on foetal growth and pregnancy outcome, are reviewed. Results from prospective studies are reviewed. Cessation of folic acid supplement use after the first trimester is associated with a sharp drop in plasma folate status and enhanced conversion of betaine to dimethylglycine. Dimethylglycine production is also higher in mothers with low folate status than in those with normal-high folate status. The effects of high doses of folic acid on one carbon metabolism in mothers with low early pregnancy cobalamin status and on foetal growth are also reviewed. Several studies report that moderately elevated early pregnancy fasting plasma total homocysteine (tHcy) is inversely associated with birth weight and a predictor of intrauterine growth retardation. There is also evidence for increased risk of preterm birth when maternal folate status is low.

Low folate status enhances pregnancy changes in plasma betaine and dimethylglycine concentrations and the association between betaine and homocysteine.

BACKGROUND: Folate, choline, and betaine participate in homocysteine metabolism. It is not known whether they interact during pregnancy. OBJECTIVE: The objective was to investigate how folate status affects choline, betaine, and dimethylglycine during pregnancy. DESIGN: Fasting plasma folate, cobalamin, free choline, betaine, dimethylglycine, and total homocysteine (tHcy) were measured longitudinally at <12, 15, 24-27, and 34 gestational weeks (GW); at labor (nonfasting); and in the cord in participants (n = 522) from the Reus-Tarragona Birth Cohort (NUTrició i Creixement Intrauterí Retardat phase). Timing, dose, and duration of folic acid supplement use were recorded. Folate status was classified as below (low) or above (high) median plasma folate at baseline (27.6 nmol/L) and at 24-27 GW (11.4 nmol/L). Associations between folate or betaine with tHcy were investigated by using multiple linear regression analysis. RESULTS: Plasma betaine decreased by 34.8% (1.0%) throughout pregnancy, and dimethylglycine increased by 39.7% (2.7%) between 24-27 GW and labor (all P < 0.001). Compared with high folate status, low status was associated with a higher dimethylglycine/betaine ratio from 15 GW and with lower plasma betaine and higher dimethylglycine from 24 to 27 GW, for the rest of pregnancy. Regression analysis showed that by 24-27 GW, both plasma folate and betaine were inversely associated with tHcy when folate status was low and that the association between betaine and tHcy depended on folate status at 24-27 and 34 GW (interaction terms: P < 0.001 and P < 0.01). Betaine was inversely associated with tHcy at labor regardless of folate status. CONCLUSION: Low folate status enhances the reduction in betaine and the increase in dimethylglycine during pregnancy and strengthens the association between betaine and tHcy. This trial was registered at clinicaltrials.gov as NCT01778205.

Vitamin B12 deficiency in the brain leads to DNA hypomethylation in the TCblR/CD320 knockout mouse.

BACKGROUND: DNA methylation is an epigenetic phenomenon that can modulate gene function by up or downregulation of gene expression. Vitamin B12 and folate pathways are involved in the production of S-Adenosylmethionine, the universal methyl donor. FINDINGS: Brain vitamin B12 concentration and global DNA methylation was determined in transcobalamin receptor (TCblR/CD320) knock out (KO) (n = 4) and control mice (n = 4) at 20-24 weeks of age. Median [IQR] brain vitamin B12 concentrations (pg/mg) in TCblR/CD320 KO mice compared with control mice was 8.59 [0.52] vs 112.42 [33.12]; p < 0.05. Global DNA methylation levels in brain genomic DNA were lower in TCblR/CD320 KO compared with control mice (Median [IQR]: 0.31[0.16] % vs 0.55[0.15] %; p < 0.05.). CONCLUSIONS: In TCblR/CD320 KO mice, brain vitamin B12 drops precipitously by as much as 90% during a 20 week period. This decrease is associated with a 40% decrease in global DNA methylation in the brain. Future research will reveal whether the disruption in gene expression profiles due to changes in DNA hypomethylation contribute to central nervous system pathologies that are frequently seen in vitamin B12 deficiency.

Homocysteine in pregnancy.

The aim of this review is to evaluate the evidence for and against fasting plasma total homocysteine (tHcy) as a biomarker/risk factor of impaired reproductive function before and during pregnancy. Apart from nutritional and lifestyle factors, tHcy is also influenced by physiological factors specific to pregnancy such as hemodilution, increased glomerular filtration rate, and endocrinological changes. These lead to a considerable reduction under normal circumstances in tHcy by midpregnancy. Stimulating excess endogenous homocysteine production before and during pregnancy in animal experiments and adding exogenous homocysteine to cell cultures result in the impairment of reproductive and developmental processes from preconception throughout pregnancy and during subsequent development of the offspring. Different studies have confirmed that elevated tHcy is a risk factor for subfertility, congenital developmental defects, preeclampsia, and intrauterine growth retardation. There is conflicting evidence that elevated tHcy is a risk factor for miscarriage, gestational diabetes, premature rupture of the membranes, placental abruption, and offspring with Down syndrome. Prospective, sufficiently powered, studies from preconception/early pregnancy are required to determine whether tHcy is a risk factor for these pregnancy complications.

Cobalamin, folic acid, and homocysteine.

Cobalamin deficiency can lead to several adverse health consequences: folate trapping in the methylation cycle and subsequent impaired DNA biosynthesis; pernicious anemia hematologically, similar to that caused by folate deficiency; elevated blood homocysteine (tHcy) (risk factor for cardiovascular disease and adverse pregnancy outcomes); and neural tube defects (NTDs). Population-wide folate status is expected to improve where folic acid fortification policies for reducing NTD occurrence are established. However, there is concern that cobalamin deficiency and its characteristic neuropathy could be masked when hematological abnormalities in risk groups such as the elderly and vegetarians are reversed through folic acid supplementation. Folate-cobalamin interactions and their impact on health are reviewed here.

The effect of nuts on inflammation.

Inflammation is one of the recognised mechanisms involved in the development of atherosclerotic plaque and insulin resistance. Inflammatory or endothelial markers such as C-Reactive Protein (CRP), Interleukin-6 (IL-6), fibrinogen, Vascular Cell Adhesion Molecule-1 (VCAM-1) and Intracellular Adhesion Molecule-1 (ICAM-1) have been identified as independent predictors of cardiovascular disease (CVD) or diabetes in human prospective studies. Epidemiological and clinical studies suggest that some dietary factors, such as n-3 polyunsaturated fatty acids, antioxidant vitamins, dietary fiber, L-arginine and magnesium may play an important role in modulating inflammation. The relationship observed between frequent nut consumption and the reduced risk of cardiovascular mortality and type 2 diabetes in some prospective studies could be explained by the fact that nuts are rich in all of these modulator nutrients. In fact, frequent nut consumption has been associated with lower concentrations of some peripheral inflammation markers in cross-sectional studies. Nut consumption has also been shown to decrease the plasma concentration of CRP, IL-6 and some endothelial markers in recent clinical trials.

Diet and lifestyle are associated with serum C-reactive protein concentrations in a population-based study.

C-reactive protein (CRP) has been proposed as an independent risk factor for cardiovascular disease. In this study we sought to investigate the association between several nutritional and lifestyle factors and serum CRP concentration in a population-based study. We studied 359 individuals (172 women, 187 men; age range 18-75 years) randomly selected from the town hall's registers and assessed their daily dietary intake using a 3-day estimated-food record. The median serum CRP concentration was 1.40 mg/L (range <0.10-47.48 mg/L; geometric mean 1.20 mg/L). We noted significant and independent direct associations between CRP and age, body-mass index, female sex, and serum triglyceride concentration. Bivariate analysis showed a significant inverse association between CRP and many nutrients (e.g., carbohydrates, proteins, lipids, thiamine, pyridoxine, tocopherol, and folate), but multiple-regression analysis indicated that only the effect of dietary folate intake was not dependent on other factors. Differences in folate intake did not produce changes in plasma homocysteine concentration, and we detected no negative correlation between dietary folate intake and log homocysteine (r = .02, P = .711). Strong positive correlations between the intake of folate and numerous other nutrients were found. This population-based study shows that a higher folate intake, in addition to other known constitutive and lifestyle factors, is significantly associated with a lower serum CRP concentration.

Regulation of serum paraoxonase activity by genetic, nutritional, and lifestyle factors in the general population.

BACKGROUND: Paraoxonase may protect lipoproteins and cell membranes from peroxidation, and alterations in the activity of this enzyme have been associated with some chronic diseases. Serum paraoxonase appears to be mainly under genetic control, but some studies suggest that environmental factors may also modulate its activity. The aim of the present study was to investigate whether diet and lifestyle affect serum paraoxonase activity. METHODS: We studied a population-based sample of 388 individuals (194 women and 194 men; age range, 18-75 years) and assessed their daily dietary intake using a 3-day estimated food record. The variables studied included serum paraoxonase activity, paraoxonase polymorphisms at positions 55 and 192, age, gender, smoking status, physical exercise, body mass index, energy consumption, nutrient intake (total lipids, saturated fatty acids, beta-carotenes, vitamins C and E), and serum lipid concentrations. RESULTS: Multiple linear regression analysis showed that only genetic polymorphisms, serum cholesterol, HDL-cholesterol concentrations, and cigarette smoking were significant predictors of serum paraoxonase activity. HDL-cholesterol concentrations were also related to body mass index, daily energy consumption, and saturated fatty acid intake. CONCLUSIONS: The between-individual variability of serum paraoxonase activity is regulated mainly by genetic determinants. Although HDL-cholesterol and tobacco smoking may contribute to the modulation of this enzyme, the other nutritional and lifestyle factors do not seem to play a significant role.