Gene response elements, genetic polymorphisms and epigenetics influence the human dietary requirement for choline

Lipidomic signatures discriminate subtle hepatic changes in the progression of porcine nonalcoholic steatohepatitis

Recently, the development of nonalcoholic steatohepatitis (NASH) in common strains of pigs has been achieved using a diet high in saturated fat, fructose, cholesterol, and cholate and deficient in choline and methionine. The aim of the present work was to characterize the hepatic and plasma lipidomic changes that accompany the progression of NASH and its reversal by switching pigs back to a chow diet. One month of this extreme steatotic diet was sufficient to induce porcine NASH. The lipidomic platform using liquid chromatography-mass spectrometry analyzed 467 lipid species. Seven hepatic phospholipids [PC(30:0), PC(32:0), PC(33:0), PC(33:1), PC(34:0), PC(34:3) and PC(36:2)] significantly discriminated the time of dietary exposure, and PC(30:0), PC(33:0), PC(33:1) and PC(34:0) showed rapid adaptation in the reversion period. Three transcripts (CS, MAT1A, and SPP1) showed significant changes associated with hepatic triglycerides and PC(33:0). Plasma lipidomics revealed that these species [FA 16:0, FA 18:0, LPC(17:1), PA(40:5), PC(37:1), TG(45:0), TG(47:2) and TG(51:0)] were able to discriminate the time of dietary exposure. Among them, FA 16:0, FA 18:0, LPC(17:1) and PA(40:5) changed the trend in the reversion phase. Plasma LDL-cholesterol and IL12P40 were good parameters to study the progression of NASH, but their capacity was surpassed by hepatic [PC(33:0), PC(33:1), and PC(34:0)] or plasma lipid [FA 16:0, FA 18:0, and LPC(17:1)] species. Taken together, these lipid species can be used as biomarkers of metabolic changes in the progression and regression of NASH in this model. The lipid changes suggest that the development of NASH also affects peripheral lipid metabolism.NEW & NOTEWORTHY A NASH stage was obtained in crossbred pigs. Hepatic [PC(33:0), PC(33:1) and PC(34:0)] or plasma [FA 16:0, FA 18:0 and LPC(17:1)] species were sensitive parameters to detect subtle changes in development and regression of nonalcoholic steatohepatitis (NASH). These findings may delineate the liquid biopsy to detect subtle changes in progression or in treatments. Furthermore, phospholipid changes according to the insult-inducing NASH may play an important role in accepting or rejecting fatty livers in transplantation.

Faecal Microbiota transplantation affects liver DNA methylation in Non-alcoholic fatty liver disease: a multi-omics approach

Individuals with nonalcoholic fatty liver disease (NAFLD) have an altered gut microbiota composition. Moreover, hepatic DNA methylation may be altered in the state of NAFLD. Using a fecal microbiota transplantation (FMT) intervention, we aimed to investigate whether a change in gut microbiota composition relates to altered liver DNA methylation in NAFLD. Moreover, we assessed whether plasma metabolite profiles altered by FMT relate to changes in liver DNA methylation. Twenty-one individuals with NAFLD underwent three 8-weekly vegan allogenic donor (n = 10) or autologous (n = 11) FMTs. We obtained hepatic DNA methylation profiles from paired liver biopsies of study participants before and after FMTs. We applied a multi-omics machine learning approach to identify changes in the gut microbiome, peripheral blood metabolome and liver DNA methylome, and analyzed cross-omics correlations. Vegan allogenic donor FMT compared to autologous FMT induced distinct differential changes in I) gut microbiota profiles, including increased abundance of Eubacterium siraeum and potential probiotic Blautia wexlerae; II) plasma metabolites, including altered levels of phenylacetylcarnitine (PAC) and phenylacetylglutamine (PAG) both from gut-derived phenylacetic acid, and of several choline-derived long-chain acylcholines; and III) hepatic DNA methylation profiles, most importantly in Threonyl-TRNA Synthetase 1 (TARS) and Zinc finger protein 57 (ZFP57). Multi-omics analysis showed that Gemmiger formicillis and Firmicutes bacterium_CAG_170 positively correlated with both PAC and PAG. E siraeum negatively correlated with DNA methylation of cg16885113 in ZFP57. Alterations in gut microbiota composition by FMT caused widespread changes in plasma metabolites (e.g. PAC, PAG, and choline-derived metabolites) and liver DNA methylation profiles in individuals with NAFLD. These results indicate that FMTs might induce metaorganismal pathway changes, from the gut bacteria to the liver.

Choline metabolism and its implications in cancer

Choline, a quintessential quaternary ammonium compound, plays a cardinal role in several pivotal biological mechanisms, chiefly in safeguarding cell membrane integrity, orchestrating methylation reactions, and synthesizing vital neurotransmitters. This systematic review meticulously dissects the complex interplay between choline metabolism and its profound implications in oncology. The exposition is stratified into three salient dimensions: Initially, we delve into the intricacies of choline metabolism, accentuating its indispensability in cellular physiology, the enzymatic labyrinth governing its flux, and the pivotal cellular import mechanisms. Subsequently, we elucidate the contemporary comprehension of choline metabolism in the cancer paradigm, traversing its influence from inception to the intricate metamorphosis during oncogenic progression, further compounded by dysregulated enzyme activities and aberrant signaling cascades. Conclusively, we illuminate the burgeoning potential of choline-centric metabolic imaging modalities, notably magnetic resonance spectroscopy (MRS) and positron emission tomography (PET), as avant-garde tools for cancer diagnostics and therapeutic trajectory monitoring. Synoptically, the nuanced perturbations in choline metabolism in neoplastic entities unfurl critical insights, potentially heralding paradigm shifts in diagnostic and therapeutic oncological stratagems. A deeper foray into this realm is anticipated to fortify our molecular understanding and refine intervention modalities in cancer theranostics.

Nutritional Genomics in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a common chronic condition associated with genetic and environmental factors in which fat abnormally accumulates in the liver. NAFLD is epidemiologically associated with obesity, type 2 diabetes, and dyslipidemia. Environmental factors, such as physical inactivity and an unbalanced diet, interact with genetic factors, such as epigenetic mechanisms and polymorphisms for the genesis and development of the condition. Different genetic polymorphisms seem to be involved in this context, including variants in PNPLA3, TM6SF2, PEMT, and CHDH genes, playing a role in the disease's susceptibility, development, and severity. From carbohydrate intake and weight loss to omega-3 supplementation and caloric restriction, different dietary and nutritional factors appear to be involved in controlling the onset and progression of NAFLD conditions influencing metabolism, gene, and protein expression. The polygenic risk score represents a sum of trait-associated alleles carried by an individual and seems to be associated with NAFLD outcomes depending on the dietary context. Understanding the exact extent to which lifestyle interventions and genetic predispositions can play a role in the prevention and management of NAFLD can be crucial for the establishment of a personalized and integrative approach to patients.

Transcriptomic Changes Highly Similar to Alzheimer's Disease Are Observed in a Subpopulation of Individuals During Normal Brain Aging

Aging is a major risk factor for late-onset Alzheimer’s disease (LOAD). How aging contributes to the development of LOAD remains elusive. In this study, we examined multiple large-scale transcriptomic datasets from both normal aging and LOAD brains to understand the molecular interconnection between aging and LOAD. We found that shared gene expression changes between aging and LOAD are mostly seen in the hippocampal and several cortical regions. In the hippocampus, the expression of phosphoprotein, alternative splicing and cytoskeleton genes are commonly changed in both aging and AD, while synapse, ion transport, and synaptic vesicle genes are commonly down-regulated. Aging-specific changes are associated with acetylation and methylation, while LOAD-specific changes are more related to glycoprotein (both up- and down-regulations), inflammatory response (up-regulation), myelin sheath and lipoprotein (down-regulation). We also found that normal aging brain transcriptomes from relatively young donors (45–70 years old) clustered into several subgroups and some subgroups showed gene expression changes highly similar to those seen in LOAD brains. Using brain transcriptomic datasets from another cohort of older individuals (>70 years), we found that samples from cognitively normal older individuals clustered with the “healthy aging” subgroup while AD samples mainly clustered with the “AD similar” subgroups. This may imply that individuals in the healthy aging subgroup will likely remain cognitively normal when they become older and vice versa. In summary, our results suggest that on the transcriptome level, aging and LOAD have strong interconnections in some brain regions in a subpopulation of cognitively normal aging individuals. This supports the theory that the initiation of LOAD occurs decades earlier than the manifestation of clinical phenotype and it may be essential to closely study the “normal brain aging” to identify the very early molecular events that may lead to LOAD development.

Maternal plasma choline and betaine in late pregnancy and child growth up to age 8 years in the KOALA Birth Cohort Study

BACKGROUND

Sufficient choline and betaine during pregnancy are needed for fetal growth and development.

OBJECTIVES

We aimed to investigate the associations between maternal plasma choline and betaine in the third trimester of pregnancy and child growth from birth up to 8 years of age.

METHODS

Concentrations of choline and betaine were measured in plasma of 1331 pregnant women from the KOALA (Kind, Ouders en gezondheid: Aandacht voor Leefstijl en Aanleg) Birth Cohort Study in the Netherlands. Child weight and height were measured at birth and at 1 (91% complete), 2 (86%), and 6-8 y (76%). Birth weight, weight gain in the first year, and z scores for weight and height at 1 and 2 y were used as continuous outcome variables. BMI z scores at 1 and 2 y were used as continuous and dichotomous outcomes, and BMI z scores at age 6-8 y were used to study overweight at that age.

RESULTS

Each 1-µmol/L increase of maternal plasma choline was associated with a mean 20-g (95% CI: 1.1, 38.0 g) higher weight gain in the first year of life, and a higher BMI z score (β: 0.02; 95% CI: 0.00, 0.04) and slightly higher odds of BMI z score >85th percentile (OR: 1.08; 95% CI: 1.03, 1.10) at 1-2 y. Each 1-µmol/L increase of plasma betaine was associated with a mean 12-g (95% CI: 0.8, 23.9 g) higher weight gain in the first year of life and higher odds of BMI z score >85th percentile at 1-2 y (OR: 1.03; 95% CI: 1.00, 1.07). Lastly, betaine was associated with overweight at 6-8 y (OR: 1.17; 95% CI: 1.02, 1.34), only in boys.

CONCLUSIONS

Third-trimester pregnancy plasma choline and betaine were positively associated with childhood anthropometric measures. In boys, some of the associations may have persisted up to 8 y of age. Further studies may investigate the validity of maternal plasma choline and betaine concentrations as markers of maternal intake and fetal transfer.

Nutrition, genetic variation and male fertility

Infertility affects nearly 50 million couples worldwide, with 40-50% of cases having a male factor component. It is well established that nutritional status impacts reproductive development, health and function, although the exact mechanisms have not been fully elucidated. Genetic variation that affects nutrient metabolism may impact fertility through nutrigenetic mechanisms. This review summarizes current knowledge on the role of several dietary components (vitamins A, B₁₂, C, D, E, folate, betaine, choline, calcium, iron, caffeine, fiber, sugar, dietary fat, and gluten) in male reproductive health. Evidence of gene-nutrient interactions and their potential effect on fertility is also examined. Understanding the relationship between genetic variation, nutrition and male fertility is key to developing personalized, DNA-based dietary recommendations to enhance the fertility of men who have difficulty conceiving.

Gut microbiome-mediated epigenetic regulation of brain disorder and application of machine learning for multi-omics data analysis

The gut-brain axis (GBA) is a biochemical link that connects the central nervous system (CNS) and enteric nervous system (ENS). Clinical and experimental evidence suggests gut microbiota as a key regulator of the GBA. Microbes living in the gut not only interact locally with intestinal cells and the ENS but have also been found to modulate the CNS through neuroendocrine and metabolic pathways. Studies have also explored the involvement of gut microbiota dysbiosis in depression, anxiety, autism, stroke, and pathophysiology of other neurodegenerative diseases. Recent reports suggest that microbe-derived metabolites can influence host metabolism by acting as epigenetic regulators. Butyrate, an intestinal bacterial metabolite, is a known histone deacetylase inhibitor that has shown to improve learning and memory in animal models. Due to high disease variability amongst the population, a multi-omics approach that utilizes artificial intelligence and machine learning to analyze and integrate omics data is necessary to better understand the role of the GBA in pathogenesis of neurological disorders, to generate predictive models, and to develop precise and personalized therapeutics. This review examines our current understanding of epigenetic regulation of the GBA and proposes a framework to integrate multi-omics data for prediction, prevention, and development of precision health approaches to treat brain disorders.

The Relationship between Choline Bioavailability from Diet, Intestinal Microbiota Composition, and Its Modulation of Human Diseases

Choline is a water-soluble nutrient essential for human life. Gut microbial metabolism of choline results in the production of trimethylamine (TMA), which, upon absorption by the host is converted into trimethylamine-N-oxide (TMAO) in the liver. A high accumulation of both components is related to cardiovascular disease, inflammatory bowel disease, non-alcoholic fatty liver disease, and chronic kidney disease. However, the relationship between the microbiota production of these components and its impact on these diseases still remains unknown. In this review, we will address which microbes contribute to TMA production in the human gut, the extent to which host factors (e.g., the genotype) and diet affect TMA production, and the colonization of these microbes and the reversal of dysbiosis as a therapy for these diseases.

Functional Expression of Choline Transporters in the Blood-Brain Barrier

Cholinergic neurons in the central nervous system play a vital role in higher brain functions, such as learning and memory. Choline is essential for the synthesis of the neurotransmitter acetylcholine by cholinergic neurons. The synthesis and metabolism of acetylcholine are important mechanisms for regulating neuronal activity. Choline is a positively charged quaternary ammonium compound that requires transporters to pass through the plasma membrane. Currently, there are three groups of choline transporters with different characteristics, such as affinity for choline, tissue distribution, and sodium dependence. They include (I) polyspecific organic cation transporters (OCT1-3: SLC22A1-3) with a low affinity for choline, (II) high-affinity choline transporter 1 (CHT1: SLC5A7), and (III) choline transporter-like proteins (CTL1-5: SLC44A1-5). Brain microvascular endothelial cells, which comprise part of the blood-brain barrier, take up extracellular choline via intermediate-affinity choline transporter-like protein 1 (CTL1) and low-affinity CTL2 transporters. CTL2 is responsible for excreting a high concentration of choline taken up by the brain microvascular endothelial cells on the brain side of the blood-brain barrier. CTL2 is also highly expressed in mitochondria and may be involved in the oxidative pathway of choline metabolism. Therefore, CTL1- and CTL2-mediated choline transport to the brain through the blood-brain barrier plays an essential role in various functions of the central nervous system by acting as the rate-limiting step of cholinergic neuronal activity.

Methyl Donor Nutrients in Chronic Kidney Disease: Impact on the Epigenetic Landscape

Epigenetic alterations, such as those linked to DNA methylation, may potentially provide molecular explanations for complications associated with altered gene expression in illnesses, such as chronic kidney disease (CKD). Although both DNA hypo- and hypermethylation have been observed in the uremic milieu, this remains only a single aspect of the epigenetic landscape and, thus, of any biochemical dysregulation associated with CKD. Nevertheless, the role of uremia-promoting alterations on the epigenetic landscape regulating gene expression is still a novel and scarcely studied field. Although few studies have actually reported alterations of DNA methylation via methyl donor nutrient intake, emerging evidence indicates that nutritional modification of the microbiome can affect one-carbon metabolism and the capacity to methylate the genome in CKD. In this review, we discuss the nutritional modifications that may affect one-carbon metabolism and the possible impact of methyl donor nutrients on the microbiome, CKD, and its phenotype.

Metabolic, Epigenetic, and Transgenerational Effects of Gut Bacterial Choline Consumption

Choline is an essential nutrient and methyl donor required for epigenetic regulation. Here, we assessed the impact of gut microbial choline metabolism on bacterial fitness and host biology by engineering a microbial community that lacks a single choline-utilizing enzyme. Our results indicate that choline-utilizing bacteria compete with the host for this nutrient, significantly impacting plasma and hepatic levels of methyl-donor metabolites and recapitulating biochemical signatures of choline deficiency. Mice harboring high levels of choline-consuming bacteria showed increased susceptibility to metabolic disease in the context of a high-fat diet. Furthermore, bacterially induced reduction of methyl-donor availability influenced global DNA methylation patterns in both adult mice and their offspring and engendered behavioral alterations. Our results reveal an underappreciated effect of bacterial choline metabolism on host metabolism, epigenetics, and behavior. This work suggests that interpersonal differences in microbial metabolism should be considered when determining optimal nutrient intake requirements.

Choline and its metabolites are differently associated with cardiometabolic risk factors, history of cardiovascular disease, and MRI-documented cerebrovascular disease in older adults

Background: There is a potential role of choline in cardiovascular and cerebrovascular disease through its involvement in lipid and one-carbon metabolism.Objective: We evaluated the associations of plasma choline and choline-related compounds with cardiometabolic risk factors, history of cardiovascular disease, and cerebrovascular pathology.Design: A cross-sectional subset of the Nutrition, Aging, and Memory in Elders cohort who had undergone MRI of the brain (n = 296; mean ± SD age: 73 ± 8.1 y) was assessed. Plasma concentrations of free choline, betaine, and phosphatidylcholine were measured with the use of liquid-chromatography-stable-isotope dilution-multiple-reaction monitoring-mass spectrometry. A volumetric analysis of MRI was used to determine the cerebrovascular pathology (white-matter hyperintensities and small- and large-vessel infarcts). Multiple linear and logistic regression models were used to examine relations of plasma measures with cardiometabolic risk factors, history of cardiovascular disease, and radiologic evidence of cerebrovascular pathology.Results: Higher concentrations of plasma choline were associated with an unfavorable cardiometabolic risk-factor profile [lower high-density lipoprotein (HDL) cholesterol, higher total homocysteine, and higher body mass index (BMI)] and greater odds of large-vessel cerebral vascular disease or history of cardiovascular disease but lower odds of small-vessel cerebral vascular disease. Conversely, higher concentrations of plasma betaine were associated with a favorable cardiometabolic risk-factor profile [lower low-density lipoprotein (LDL) cholesterol and triglycerides] and lower odds of diabetes. Higher concentrations of plasma phosphatidylcholine were associated with characteristics of both a favorable cardiometabolic risk-factor profile (higher HDL cholesterol, lower BMI, lower C-reactive protein, lower waist circumference, and lower odds of hypertension and diabetes) and an unfavorable profile (higher LDL cholesterol and triglycerides).Conclusion: Choline and its metabolites have differential associations with cardiometabolic risk factors and subtypes of vascular disease, thereby suggesting differing roles in the pathogenesis of cardiovascular and cerebral large-vessel disease compared with that of small-vessel disease.

Genetic Variation in Choline-Metabolizing Enzymes Alters Choline Metabolism in Young Women Consuming Choline Intakes Meeting Current Recommendations

Single nucleotide polymorphisms (SNPs) in choline metabolizing genes are associated with disease risk and greater susceptibility to organ dysfunction under conditions of dietary choline restriction. However, the underlying metabolic signatures of these variants are not well characterized and it is unknown whether genotypic differences persist at recommended choline intakes. Thus, we sought to determine if common genetic risk factors alter choline dynamics in pregnant, lactating, and non-pregnant women consuming choline intakes meeting and exceeding current recommendations. Women (n = 75) consumed 480 or 930 mg choline/day (22% as a metabolic tracer, choline-d9) for 10–12 weeks in a controlled feeding study. Genotyping was performed for eight variant SNPs and genetic differences in metabolic flux and partitioning of plasma choline metabolites were evaluated using stable isotope methodology. CHKA rs10791957, CHDH rs9001, CHDH rs12676, PEMT rs4646343, PEMT rs7946, FMO3 rs2266782, SLC44A1 rs7873937, and SLC44A1 rs3199966 altered the use of choline as a methyl donor; CHDH rs9001 and BHMT rs3733890 altered the partitioning of dietary choline between betaine and phosphatidylcholine synthesis via the cytidine diphosphate (CDP)-choline pathway; and CHKA rs10791957, CHDH rs12676, PEMT rs4646343, PEMT rs7946 and SLC44A1 rs7873937 altered the distribution of dietary choline between the CDP-choline and phosphatidylethanolamine N-methyltransferase (PEMT) denovo pathway. Such metabolic differences may contribute to disease pathogenesis and prognosis over the long-term.

Role of Choline in the Modulation of Degenerative Processes: In Vivo and In Vitro Studies

The purpose of the present study was to examine the nutraceutical potential of choline as an added value to its well-known brain nutrient role. Several toxicity, antitoxicity, genotoxicity, antigenotoxicity, and longevity endpoints were checked in the somatic mutation and recombination test in in vivo Drosophila animal model. Cytotoxicity in human leukemia-60 cell line (HL-60) promyelocytic and NIH3T3 mouse fibroblast cells, proapoptotic DNA fragmentation, comet assay, methylation status, and macroautophagy (MA) activity were tested in in vitro assays. Choline is not only safe but it is also able to protect against the DNA damage caused by an oxidative genotoxin. Moreover, it improves the life extension in the animal model. The in vitro results show that it is able to exhibit genetic damage against leukemia HL-60 cells. Single-strand breaks in DNA are observed at the molecular level in treatments with choline, although only a significant hypermethylation on the long interspersed elements-1 and a hypomethylation on the satellite-alpha DNA repetitive DNA sequences of HL-60 cells at the lowest concentration (0.447 mM) were observed. Besides, choline decreased MA at the lower assayed concentration and the MA response to topoisomerase inhibitor (etoposide) is maintained in the presence of treatment with 0.22 mM choline. Taking into account the hopeful results obtained in the in vivo and in vitro assays, choline could be proposed as a substance with an important nutraceutical value for different purposes.

Randomized, double-blind, placebo-controlled clinical trial of choline supplementation in school-aged children with fetal alcohol spectrum disorders

BACKGROUND

Prenatal alcohol exposure results in a broad range of cognitive and behavioral impairments. Because of the long-lasting problems that are associated with fetal alcohol spectrum disorders (FASDs), the development of effective treatment programs is critical. Preclinical animal studies have shown that choline, which is an essential nutrient, can attenuate the severity of alcohol-related cognitive impairments.

OBJECTIVE

We aimed to translate preclinical findings to a clinical population to investigate whether choline supplementation can ameliorate the severity of memory, executive function, and attention deficits in children with FASDs.

DESIGN

In the current study, which was a randomized, double-blind, placebo-controlled clinical trial, we explored the effectiveness of a choline intervention for children with FASDs who were aged 5-10 y. Fifty-five children with confirmed histories of heavy prenatal alcohol exposure were randomly assigned to either the choline (n = 29) or placebo (n = 26) treatment arms. Participants in the choline group received 625 mg choline/d for 6 wk, whereas subjects in the placebo group received an equivalent dose of an inactive placebo treatment. Primary outcomes, including the performance on neuropsychological measures of memory, executive function, and attention and hyperactivity, were assessed at baseline and postintervention.

RESULTS

Compared with the placebo group, participants in the choline group did not differentially improve in cognitive performance in any domain. Treatment compliance and mean dietary choline intake were not predictive of treatment outcomes.

CONCLUSIONS

Findings of the current study do not support that choline, administered at a dose of 625 mg/d for 6 wk, is an effective intervention for school-aged (5-10 y old) children with FASDs. This research provides important information about choline's therapeutic window. Combined with other studies of choline and nutritional interventions in this population, this study emphasizes a further need for the continued study of the role of nutritional status and supplementation in children with FASDs and the contributions of nutrition to neurocognition. This trial was registered at clinicaltrials.gov as NCT01911299.

Functional expression of choline transporter like-protein 1 (CTL1) and CTL2 in human brain microvascular endothelial cells

In this study, we examined the molecular and functional characterization of choline transporter in human brain microvascular endothelial cells (hBMECs). Choline uptake into hBMECs was a saturable process that was mediated by a Na(+)-independent, membrane potential and pH-dependent transport system. The cells have two different [(3)H]choline transport systems with Km values of 35.0 ± 4.9 μM and 54.1 ± 8.1 μM, respectively. Choline uptake was inhibited by choline, acetylcholine (ACh) and the choline analog hemicholinium-3 (HC-3). Various organic cations also interacted with the choline transport system. Choline transporter-like protein 1 (CTL1) and CTL2 mRNA were highly expressed, while mRNA for high-affinity choline transporter 1 (CHT1) and organic cation transporters (OCTs) were not expressed in hBMECs. CTL1 and CTL2 proteins were localized to brain microvascular endothelial cells in human brain cortical sections. Both CTL1 and CTL2 proteins were expressed on the plasma membrane and mitochondria. CTL1 and CTL2 proteins are mainly expressed in plasma membrane and mitochondria, respectively. We conclude that choline is mainly transported via an intermediate-affinity choline transport system, CTL1 and CTL2, in hBMECs. These transporters are responsible for the uptake of extracellular choline and organic cations. CTL2 participate in choline transport mainly in mitochondria, and may be the major site for the control of choline oxidation.

Maternal Choline Status, but Not Fetal Genotype, Influences Cord Plasma Choline Metabolite Concentrations

BACKGROUND

Choline deficiency during pregnancy can lead to adverse birth outcomes, including impaired neurodevelopment and birth defects. Genetic variants of choline and one-carbon metabolism may also influence birth outcomes by altering plasma choline concentrations. The effects of maternal ad libitum choline intake during pregnancy and fetal genetic variants on maternal and cord concentrations of choline and its metabolites are unknown.

OBJECTIVES

This prospective study sought to assess the effect of 1) maternal dietary choline intake on maternal and cord plasma concentrations of choline and its metabolites, and 2) fetal genetic polymorphisms on cord plasma concentrations.

METHODS

The dietary choline intake of 368 pregnant Canadian women was assessed in early (0-16 wk) and late (23-37 wk) pregnancy with the use of a food frequency questionnaire. Plasma concentrations of free choline and its metabolites were measured in maternal samples at recruitment and delivery, and in the cord blood. Ten fetal genetic variants in choline and one-carbon metabolism were assessed for their association with cord plasma concentrations of free choline and its metabolites.

RESULTS

Mean maternal plasma free choline, dimethylglycine, and trimethylamine N-oxide (TMAO) concentrations increased during pregnancy by 49%, 17%, and 13%, respectively (P < 0.005), whereas betaine concentrations decreased by 21% (P < 0.005). Cord plasma concentrations of free choline, betaine, dimethylglycine, and TMAO were 3.2, 2.0, 1.3, and 0.88 times corresponding maternal concentrations at delivery, respectively (all P < 0.005). Maternal plasma concentrations of betaine, dimethylglycine, and TMAO (r(2) = 0.19-0.51; P < 0.0001) at delivery were moderately strong, whereas maternal concentrations of free choline were not significant (r(2) = 0.12; P = 0.06), predictors of cord plasma concentrations of these metabolites. Neither maternal dietary intake nor fetal genetic variants predicted maternal or cord plasma concentrations of choline and its metabolites.

CONCLUSION

These data collectively indicate that maternal choline status, but not fetal genotype, influences cord plasma concentrations of choline metabolites. This trial was registered at clinicaltrials.gov as NCT02244684.

MTHFR deficiency or reduced intake of folate or choline in pregnant mice results in impaired short-term memory and increased apoptosis in the hippocampus of wild-type offspring

Genetic or nutritional disturbances in one-carbon metabolism, with associated hyperhomocysteinemia, can result in complex disorders including pregnancy complications and neuropsychiatric diseases. In earlier work, we showed that mice with a complete deficiency of methylenetetrahydrofolate reductase (MTHFR), a critical enzyme in folate and homocysteine metabolism, had cognitive impairment with disturbances in choline metabolism. Maternal demands for folate and choline are increased during pregnancy and deficiencies of these nutrients result in several negative outcomes including increased resorption and delayed development. The goal of this study was to investigate the behavioral and neurobiological impact of a maternal genetic deficiency in MTHFR or maternal nutritional deficiency of folate or choline during pregnancy on 3-week-old Mthfr(+/+) offspring. Mthfr(+/+) and Mthfr(+/-) females were placed on control diets (CD); and Mthfr(+/+) females were placed on folate-deficient diets (FD) or choline-deficient diets (ChDD) throughout pregnancy and lactation until their offspring were 3weeks of age. Short-term memory was assessed in offspring, and hippocampal tissue was evaluated for morphological changes, apoptosis, proliferation and choline metabolism. Maternal MTHFR deficiency resulted in short-term memory impairment in offspring. These dams had elevated levels of plasma homocysteine when compared with wild-type dams. There were no differences in plasma homocysteine in offspring. Increased apoptosis and proliferation was observed in the hippocampus of offspring from Mthfr(+/-) mothers. In the maternal FD and ChDD study, offspring also showed short-term memory impairment with increased apoptosis in the hippocampus; increased neurogenesis was observed in ChDD offspring. Choline acetyltransferase protein was increased in the offspring hippocampus of both dietary groups and betaine was decreased in the hippocampus of FD offspring. Our results reveal short-term memory deficits in the offspring of dams with MTHFR deficiency or dietary deficiencies of critical methyl donors. We suggest that deficiencies in maternal one-carbon metabolism during pregnancy can contribute to hippocampal dysfunction in offspring through apoptosis or altered choline metabolism.

Epigenetics and nutritional environmental signals

All terrestrial life is influenced by multi-directional flows of information about its environment, enabling malleable phenotypic change through signals, chemical processes, or various forms of energy that facilitate acclimatization. Billions of biological co-inhabitants of the earth, including all plants and animals, collectively make up a genetic/epigenetic ecosystem by which adaptation/survival (inputs and outputs) are highly interdependent on one another. As an ecosystem, the solar system, rotation of the planets, changes in sunlight, and gravitational pull influence cyclic epigenetic transitions and chromatin remodeling that constitute biological circadian rhythms controlling senescence. In humans, adverse environmental conditions such as poverty, stress, alcohol, malnutrition, exposure to pollutants generated from industrialization, man-made chemicals, and use of synthetic drugs can lead to maladaptive epigenetic-related illnesses with disease-specific genes being atypically activated or silenced. Nutrition and dietary practices are one of the largest facets in epigenetic-related metabolism, where specific "epi-nutrients" can stabilize the genome, given established roles in DNA methylation, histone modification, and chromatin remodeling. Moreover, food-based "epi-bioactive" constituents may reverse maladaptive epigenetic patterns, not only prior to conception and during fetal/early postnatal development but also through adulthood. In summary, in contrast to a static genomic DNA structure, epigenetic changes are potentially reversible, raising the hope for therapeutic and/or dietary interventions that can reverse deleterious epigenetic programing as a means to prevent or treat major illnesses.

Focus on genetic and epigenetic events of colorectal cancer pathogenesis: implications for molecular diagnosis

Originally, colorectal cancer (CRC) tumorigenesis was understood as a multistep process that involved accumulation of tumor suppressor genes and oncogenes mutations, such as APC, TP53 and KRAS. However, this assumption proposed a relatively limited repertoire of genetic alterations. In the last decade, there have been major advances in knowledge of multiple molecular pathways involved in CRC pathogenesis, particularly regarding cytogenetic and epigenetic events. Microsatellite instability, chromosomal instability and CpG island methylator phenotype are the most analyzed cytogenetic changes, while DNA methylation, modifications in histone proteins and microRNAs (miRNAs) were analyzed in the field of epigenetic alterations. Therefore, CRC development results from interactions at many levels between genetic and epigenetic amendments. Furthermore, hereditary cancer syndrome and individual or environmental risk factors should not be ignored. The difficulties in this setting are addressed to understand the molecular basis of individual susceptibility to CRC and to determine the roles of genetic and epigenetic alterations, in order to yield more effective prevention strategies in CRC patients and directing their treatment. This review summarizes the most investigated biomolecular pathways involved in CRC pathogenesis, their role as biomarkers for early CRC diagnosis and their possible use to stratify susceptible patients into appropriate screening or surveillance programs.

The role of folic acid fortification in neural tube defects: a review

The worldwide prevalence of neural tube defects (NTDs) has fallen noticeably during the past 30 years, but the specific etiology and causative mechanism of NTDs remain unknown. Since introduction of mandatory fortification of grains with folic acid, a further decrease in NTD prevalence has been reported in North America and other countries with large variations among ethnic subgroups. However, a significant portion of NTDs still persists. Population data suggest that women of childbearing age may not yet be adequately targeted, while the general population may be overfortified with folic acid. While an excessive folate intake may be associated with adverse effects, there remains uncertainty about the minimum effective folate intake and status required for NTD prevention, and the safe upper folate level. Besides folate, several other lifestyle and environmental factors as well as genetic variations may influence NTD development, possibly by affecting one-carbon metabolism and thus epigenetic events. In conclusion, mandatory folic acid fortification plays a significant part in the reduction of NTD prevalence, but possibly at a cost and with a portion of NTDs remaining. More effective preventive strategies require better understanding of the etiology of this group of birth defects.

Microbial modulation of host immunity with the small molecule phosphorylcholine

All microorganisms dependent on persistence in a host for survival rely on either hiding from or modulating host responses to infection. The small molecule phosphorylcholine, or choline phosphate (ChoP), is used for both of these purposes by a wide array of bacterial and parasitic microbes. While the mechanisms underlying ChoP acquisition and expression are diverse, a unifying theme is the use of ChoP to reduce the immune response to infection, creating an advantage for ChoP-expressing microorganisms. In this minireview, we discuss several benefits of ChoP expression during infection as well as how the immune system fights back against ChoP-expressing pathogens.

Phosphatidylcholine supplementation in pregnant women consuming moderate-choline diets does not enhance infant cognitive function: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Choline is essential for fetal brain development, and it is not known whether a typical American diet contains enough choline to ensure optimal brain development.

OBJECTIVE

The study was undertaken to determine whether supplementing pregnant women with phosphatidylcholine (the main dietary source of choline) improves the cognitive abilities of their offspring.

DESIGN

In a double-blind, randomized controlled trial, 140 pregnant women were randomly assigned to receive supplemental phosphatidylcholine (750 mg) or a placebo (corn oil) from 18 wk gestation through 90 d postpartum. Their infants (n = 99) were tested for short-term visuospatial memory, long-term episodic memory, language development, and global development at 10 and 12 mo of age.

RESULTS

The women studied ate diets that delivered ∼360 mg choline/d in foods (∼80% of the recommended intake for pregnant women, 65% of the recommended intake for lactating women). The phosphatidylcholine supplements were well tolerated. Groups did not differ significantly in global development, language development, short-term visuospatial memory, or long-term episodic memory.

CONCLUSIONS

Phosphatidylcholine supplementation of pregnant women eating diets containing moderate amounts of choline did not enhance their infants' brain function. It is possible that a longer follow-up period would reveal late-emerging effects. Moreover, future studies should determine whether supplementing mothers eating diets much lower in choline content, such as those consumed in several low-income countries, would enhance infant brain development.

DNA methylation program during development

DNA methylation is a key epigenetic mark when occurring in the promoter and enhancer regions regulates the accessibility of the binding protein and gene transcription. DNA methylation is inheritable and can be de novo-synthesized, erased and reinstated, making it arguably one of the most dynamic upstream regulators for gene expression and the most influential pacer for development. Recent progress has demonstrated that two forms of cytosine methylation and two pathways for demethylation constitute ample complexity for an instructional program for orchestrated gene expression and development. The forum of the current discussion and review are whether there is such a program, if so what the DNA methylation program entails, and what environment can change the DNA methylation program. The translational implication of the DNA methylation program is also proposed.

Choline deprivation: an overview of the major hepatic metabolic response pathways

Choline (Ch) is an important nutrient that is involved in many physiological functions. Deprivation of Ch (CD) may lead to hepatocellular modifications and/or even hepatic tumorigenesis and it can be a frequent problem in clinical settings; it can accompany various common pathological (alcoholism and malnutrition) or physiological states (pregnancy and lactation). The aim of this review is to provide an up-to-date overview of the major metabolic pathways involved in the hepatic response toward the experimentally or clinically induced CD, and to shed more light on the implicated (and probably interrelated) mechanisms responsible for the observed hepatocellular modifications and/or carcinogenesis.

Computational methods to work as first-pass filter in deleterious SNP analysis of alkaptonuria

A major challenge in the analysis of human genetic variation is to distinguish functional from nonfunctional SNPs. Discovering these functional SNPs is one of the main goals of modern genetics and genomics studies. There is a need to effectively and efficiently identify functionally important nsSNPs which may be deleterious or disease causing and to identify their molecular effects. The prediction of phenotype of nsSNPs by computational analysis may provide a good way to explore the function of nsSNPs and its relationship with susceptibility to disease. In this context, we surveyed and compared variation databases along with in silico prediction programs to assess the effects of deleterious functional variants on protein functions. In other respects, we attempted these methods to work as first-pass filter to identify the deleterious substitutions worth pursuing for further experimental research. In this analysis, we used the existing computational methods to explore the mutation-structure-function relationship in HGD gene causing alkaptonuria.

Potential value of nutrigenomics in Crohn's disease

Crohn's disease is a chronic relapsing condition that has no certain cure. Both genetic susceptibility and nutrition have key roles, but their level of involvement varies between patients. Interacting gene pathways influence the probability of disease development, but these are affected by stress and various environmental factors, including diet. In addition, the role of the gut microbiome must not be underestimated, as it is substantially altered in patients with Crohn's disease. Although an elemental diet might lead to disease remission, reintroducing real foods and sustainable diets in patients with Crohn's disease is currently difficult, and would benefit from the sensitivity and rapid feedback provided by the field of nutrigenomics. Nutrigenomics utilizes high-throughput genomics technologies to reveal changes in gene and protein expression that are modulated by the patient's nutrition. The most widely used technique thus far is transcriptomics, which permits measurement of changes in the expression of thousands of genes simultaneously in one sample. Given the volume of numbers generated in such studies, data-basing and bioinformatics are essential to ensure the correct application of nutrigenomics at the population level. These methods have been successfully applied to animal models of Crohn's disease, and the time is right to move them to human studies.

The effects of dietary choline

Food intake can influence neuronal functions through different modulators expressed in the brain. The present review is a report through relevant experimental findings on the effects of choline, a nutritional component found in the diet, to identify a safe and effective dietary solution that can offer some protection against neurotoxicity and neurological disorders and that can be implemented in animals and humans in a very short period of time.

Supplemental dietary choline during development exerts antidepressant-like effects in adult female rats

Perinatal choline supplementation in rats is neuroprotective against insults such as fetal alcohol exposure, seizures, and advanced age. In the present study we explored whether dietary choline supplementation may also confer protection from psychological challenges, like stress, and act as a natural buffer against stress-linked psychological disorders, like depression. We previously found that choline supplementation increased adult hippocampal neurogenesis, a function compromised by stress, lowered in depression, and boosted by antidepressants; and increased levels of growth factors linked to depression, like brain-derived neurotrophic factor. Together, these were compelling reasons to study the role of choline in depressed mood. To do this, we treated rats with a choline supplemented diet (5 mg/kg choline chloride in AIN76A) prenatally on embryonic days 10-22, on postnatal days (PD) 25-50, or as adults from PD75 onward. Outside of these treatment periods rats were fed a standard diet (1.1 mg/kg choline chloride in AIN76A); control rats consumed only this diet throughout the study. Starting on PD100 rats' anxiety-like responses to an open field, learning in a water maze, and reactivity to forced swimming were assessed. Rats given choline supplementation during pre- or post-natal development, but not adult-treated rats, were less anxious in the open field and less immobile in the forced swim test than control rats. These effects were not mediated by a learning deficit as all groups performed comparably and well in the water maze. Thus, we offer compelling support for the hypothesis that supplemental dietary choline, at least when given during development, may inoculate an individual against stress and major psychological disorders, like depression.

Perturbations of lipid metabolism indexed by lipidomic biomarkers

The lipidome of the liver and the secreted circulating lipoproteins can now be interrogated conveniently by automated mass spectrometric methods. Multivariate analysis of the liver and serum lipid composition in various animal modes or in human patients has pointed to specific molecular species markers. The perturbations of lipid metabolism can be categorized on the basis of three basic pathological mechanisms: (1) an accelerated rate of de novo lipogenesis; (2) perturbation of the peroxisome pathway of ether-lipid and very-long-chain fatty acid biosynthesis; (3) a change in the rate of interconversion of essential omega-3 and -6 polyunsaturated fatty acids. This review provides examples to illustrate the practicalities of lipidomic studies in biomedicine.

Nutritional genomics: defining the dietary requirement and effects of choline

As it becomes evident that single nucleotide polymorphisms (SNPs) in humans can create metabolic inefficiencies, it is reasonable to ask if such SNPs influence dietary requirements. Epidemiologic studies that examine SNPs relative to risks for diseases are common, but there are few examples of clinically sized nutrition studies that examine how SNPs influence metabolism. Studies on how SNPs influence the dietary requirement for choline provide a model for how we might begin examining the effects of SNPs on nutritional phenotypes using clinically sized studies (clinical nutrigenomics). Most men and postmenopausal women develop liver or muscle dysfunction when deprived of dietary choline. More than one-half of premenopausal women may be resistant to choline deficiency-induced organ dysfunction, because estrogen induces the gene [phosphatidylethanolamine-N-methyltransferase (PEMT)] that catalyzes endogenous synthesis of phosphatidylcholine, which can subsequently yield choline. Those premenopausal women that do require a dietary source of choline have a SNP in PEMT, making them unresponsive to estrogen induction of PEMT. It is important to recognize differences in dietary requirements for choline in women, because during pregnancy, maternal dietary choline modulates fetal brain development in rodent models. Because choline metabolism and folate metabolism intersect at the methylation of homocysteine, manipulations that limit folate availability also increase the use of choline as a methyl donor. People with a SNPs in MTHFD1 (a gene of folate metabolism that controls the use of folate as a methyl donor) are more likely to develop organ dysfunction when deprived of choline; their dietary requirement is increased because of increased need for choline as a methyl donor.

Association between composition of the human gastrointestinal microbiome and development of fatty liver with choline deficiency

BACKGROUND & AIMS

Nonalcoholic fatty liver disease affects up to 30% of the US population, but the mechanisms underlying this condition are incompletely understood. We investigated how diet standardization and choline deficiency influence the composition of the microbial community in the human gastrointestinal tract and the development of fatty liver under conditions of choline deficiency.

METHODS

We performed a 2-month inpatient study of 15 female subjects who were placed on well-controlled diets in which choline levels were manipulated. We used 454-FLX pyrosequencing of 16S ribosomal RNA bacterial genes to characterize microbiota in stool samples collected over the course of the study.

RESULTS

The compositions of the gastrointestinal microbial communities changed with choline levels of diets; each individual's microbiome remained distinct for the duration of the experiment, even though all subjects were fed identical diets. Variations between subjects in levels of Gammaproteobacteria and Erysipelotrichi were directly associated with changes in liver fat in each subject during choline depletion. Levels of these bacteria, change in amount of liver fat, and a single nucleotide polymorphism that affects choline were combined into a model that accurately predicted the degree to which subjects developed fatty liver on a choline-deficient diet.

CONCLUSIONS

Host factors and gastrointestinal bacteria each respond to dietary choline deficiency, although the gut microbiota remains distinct in each individual. We identified bacterial biomarkers of fatty liver that result from choline deficiency, adding to the accumulating evidence that gastrointestinal microbes have a role in metabolic disorders.

Genetics, cytogenetics, and epigenetics of colorectal cancer

Most of the colorectal cancer (CRC) cases are sporadic, only 25% of the patients have a family history of the disease, and major genes causing syndromes predisposing to CRC only account for 5-6% of the total cases. The following subtypes can be recognized: MIN (microsatellite instability), CIN (chromosomal instability), and CIMP (CpG island methylator phenotype). CIN occurs in 80-85% of CRC. Chromosomal instability proceeds through two major mechanisms, missegregation that results in aneuploidy through the gain or loss of whole chromosomes, and unbalanced structural rearrangements that lead to the loss and/or gain of chromosomal regions. The loss of heterozygosity that occur in the first phases of the CRC cancerogenesis (in particular for the genes on 18q) as well as the alteration of methylation pattern of multiple key genes can drive the development of colorectal cancer by facilitating the acquisition of multiple tumor-associated mutations and the instability phenotype.

Choline and betaine in health and disease

Choline is an essential nutrient, but is also formed by de novo synthesis. Choline and its derivatives serve as components of structural lipoproteins, blood and membrane lipids, and as a precursor of the neurotransmitter acetylcholine. Pre-and postnatal choline availability is important for neurodevelopment in rodents. Choline is oxidized to betaine that serves as an osmoregulator and is a substrate in the betaine-homocysteine methyltransferase reaction, which links choline and betaine to the folate-dependent one-carbon metabolism. Choline and betaine are important sources of one-carbon units, in particular, during folate deficiency. Choline or betaine supplementation in humans reduces concentration of total homocysteine (tHcy), and plasma betaine is a strong predictor of plasma tHcy in individuals with low plasma concentration of folate and other B vitamins (B₂, B₆, and B₁₂) in combination TT genotype of the methylenetetrahydrofolate reductase 677 C->T polymorphism. The link to one-carbon metabolism and the recent availability of food composition data have motivated studies on choline and betaine as risk factors of chronic diseases previously studied in relation to folate and homocysteine status. High intake and plasma level of choline in the mother seems to afford reduced risk of neural tube defects. Intake of choline and betaine shows no consistent relation to cancer or cardiovascular risk or risk factors, whereas an unfavorable cardiovascular risk factor profile was associated with high choline and low betaine concentrations in plasma. Thus, choline and betaine showed opposite relations with key components of metabolic syndrome, suggesting a disruption of mitochondrial choline oxidation to betaine as part of the mitochondrial dysfunction in metabolic syndrome.

Choline in acute coronary syndrome: an emerging biomarker with implications for the integrated assessment of plaque vulnerability

Whole-blood choline, plasma choline and serum choline are emerging biomarkers in acute coronary syndrome related to coronary plaque instability with platelet thrombus formation and ischemia. Whole-blood choline is an early predictor for cardiac events, which adds to troponins, natriuretic peptides and inflammatory markers. Serum choline is highly predictive for myocardial infarction and discriminates high- from low-risk subgroups in troponin-positive patients. Choline is a candidate marker to aid decision making in the emergency room in the upcoming era of sensitive troponin tests and the growing need to differentiate between ischemic and nonischemic etiologies of troponin elevations. The integrated approach of in vitro choline measurement in combination with advanced techniques of in vivo choline imaging represents a novel future strategy for detecting vulnerable plaques. This paper provides an up-to-date review of choline in acute coronary syndrome including key aspects of pathophysiology, analytical methods, clinical studies and implications for the integrated assessment of plaque vulnerability.

Impact of smoking and chewing tobacco on arsenic-induced skin lesions

BACKGROUND

We recently reported that the main reason for the documented higher prevalence of arsenic-related skin lesions among men than among women is the result of less efficient arsenic metabolism.

OBJECTIVE

Because smoking has been associated with less efficient arsenic methylation, we aimed to elucidate interactions between tobacco use and arsenic metabolism for the risk of developing skin lesions.

METHODS

We used a population-based case-referent study that showed increased risk for skin lesions in relation to chronic arsenic exposure via drinking water in Bangladesh and randomly selected 526 of the referents (random sample of inhabitants > 4 years old; 47% male) and all 504 cases (54% male) with arsenic-related skin lesions to measure arsenic metabolites [methylarsonic acid (MA) and dimethylarsinic acid (DMA)] in urine using high-performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICPMS).

RESULTS

The odds ratio for skin lesions was almost three times higher in the highest tertile of urinary %MA than in the lowest tertile. Men who smoked cigarettes and bidis (locally produced cigarettes; 33% of referents, 58% of cases) had a significantly higher risk for skin lesions than did nonsmoking men; this association decreased slightly after accounting for arsenic metabolism. Only two women smoked, but women who chewed tobacco (21% of referents, 43% of cases) had a considerably higher risk of skin lesions than did women who did not use tobacco. The odds ratio (OR) for women who chewed tobacco and who had < or = 7.9%MA was 3.8 [95% confidence interval (CI), 1.4-10] compared with women in the same MA tertile who did not use tobacco. In the highest tertile of %MA or %inorganic arsenic (iAs), women who chewed tobacco had ORs of 7.3 and 7.5, respectively, compared with women in the lowest tertiles who did not use tobacco.

CONCLUSION

The increased risk of arsenic-related skin lesions in male smokers compared with nonsmokers appears to be partly explained by impaired arsenic methylation, while there seemed to be an excess risk due to interaction between chewing tobacco and arsenic metabolism in women.

Choline: an essential nutrient for public health

Choline was officially recognized as an essential nutrient by the Institute of Medicine (IOM) in 1998. There is significant variation in the dietary requirement for choline that can be explained by common genetic polymorphisms. Because of its wide-ranging roles in human metabolism, from cell structure to neurotransmitter synthesis, choline-deficiency is now thought to have an impact on diseases such as liver disease, atherosclerosis, and, possibly, neurological disorders. Choline is found in a wide variety of foods. Eggs and meats are rich sources of choline in the North American diet, providing up to 430 milligrams per 100 grams. Mean choline intakes for older children, men, women, and pregnant women are far below the adequate intake level established by the IOM. Given the importance of choline in a wide range of critical functions in the human body, coupled with less-than-optimal intakes among the population, dietary guidance should be developed to encourage the intake of choline-rich foods.

Enhanced one-carbon flux towards DNA methylation: Effect of dietary methyl supplements against gamma-radiation-induced epigenetic modifications

Radiation exposure poses a major risk for workers in the nuclear power plants and other radiation related industry. In this context, we demonstrate that gamma-radiation is an efficient DNA demethylating agent and its injurious effect can be minimized by dietary methyl supplements (folate, choline and vitamin B12). To elucidate the possible underlying mechanism(s), male Swiss mice were maintained on normal control diet (NCD) and methyl-supplemented diet (MSD). After 2 weeks of NCD and MSD dietary regimen, we exposed the animals to gamma-radiation (2, 4 and 6Gy) and investigated the profile of downstream metabolites and activity levels of one-carbon (C(1)) flux generating enzymes. In MSD fed and irradiated animals, hepatic folate levels increased (P<0.01), while hepatic homocysteine levels decreased (P<0.01) compared to NCD fed and irradiated animals. Although hepatic folate level increased significantly in MSD fed animals (P<0.01), it showed a decrease in response to high doses of gamma-irradiation. Under these conditions, a marked suppression of S-adenosylmethionine (SAM) levels occurred in NCD fed and irradiated animals, suggesting reduced conversion of homocysteine to SAM. Concomitant with decline in liver SAM Pool, activities of DNA methyltransferase (Dnmt, that methylates DNA) and methionine synthase (MSase, that regenerates methionine from homocysteine) were both decreased in NCD fed and irradiated mice. However, in MSD fed and irradiated mice, they were increased. These results strongly indicated that increased levels of dnmt and MSase may enhance C(1) flux towards DNA methylation reactions in MSD fed animals. These results were confirmed and further substantiated by measuring genomic DNA methylation levels, which were maintained at normal levels in MSD fed and irradiated mice compared to NCD fed and irradiated animals (P<0.01). In conclusion, our results suggest that maintenance of genomic DNA methylation under gamma-radiation stress might be a very dynamic, progressive diet dependent process that could involve increased one-carbon flux through various C(1) metabolites.

Functional characterization of phospholipid N-methyltransferases from Arabidopsis and soybean

Phospholipid N-methyltransferase (PLMT) enzymes catalyze the S-adenosylmethionine-dependent methylation of ethanolamine-containing phospholipids to produce the abundant membrane lipid phosphatidylcholine (PtdCho). In mammals and yeast, PLMT activities are required for the de novo synthesis of the choline headgroup found in PtdCho. PLMT enzyme activities have also been reported in plants, yet their roles in PtdCho biosynthesis are less clear because most plants can produce the choline headgroup entirely via soluble substrates, initiated by the methylation of free ethanolamine-phosphate. To gain further insights into the function of PLMT enzymes in plants, we isolated PLMT cDNAs from Arabidopsis and soybean (Glycine max) based upon primary amino acid sequence homology to the rat PLMT, phosphatidylethanolamine N-methyltransferase. Using a heterologous yeast expression system, it was shown that plant PLMTs methylate phosphatidylmonomethylethanolamine and phosphatidyldimethylethanolamine but cannot utilize phosphatidylethanolamine as a substrate. Identification of an Arabidopsis line containing a knock-out dissociator transposon insertion within the single copy AtPLMT gene allowed us to investigate the consequences of loss of PLMT function. Although the accumulation of the PLMT substrates phosphatidylmonomethylethanolamine and phosphatidyldimethylethanolamine was considerably elevated in the atplmt knock-out line, PtdCho levels remained normal, and no obvious differences were observed in plant morphology or development under standard growth conditions. However, because the metabolic routes through which PtdCho is synthesized in plants vary greatly among differing species, it is predicted that the degree with which PtdCho synthesis is dependent upon PLMT activities will also vary widely throughout the plant kingdom.

Acetylcholine rescues two-cell block through activation of IP3 receptors and Ca2+/calmodulin-dependent kinase II in an ICR mouse strain

Acetylcholine (ACh) causes early activation events in mouse oocytes, but little is known about its precise role in the early embryonic development of mice. We aimed to determine whether and how ACh is capable of rescuing two-cell block in an in vitro culture system. ACh evoked different transient Ca(2+) patterns showing a higher Ca(2+) peak in the two-cell stage embryos (two-cells) than observed in mature oocytes. In early two-cells subjected to an in vitro two-cell block, xestospongin C (Xes-C), an IP3 receptor antagonist, significantly decreased the level of the ACh-induced Ca(2+) increase. The reduction in the ACh-induced Ca(2+) increase by Xes-C in late two-cells was lower than that in early two-cells. Furthermore, KN62 and KN93, both CaMKII inhibitors, were found to reduce the magnitude of the ACh-induced Ca(2+) increase in early two-cells. The addition of ACh to the culture medium showed an ability to rescue in vitro two-cell block. However, the addition of ACh together with both Xes-C and CaMKII inhibitors or with either inhibitor separately had no effect on the rescue of two-cell block. Long-term exposure of late two-cells to ACh decreased morula and early blastocyst development and ACh had a differential effect on early and late two-cells. These results indicate that ACh likely rescues the in vitro two-cell block through activation of IP3R- and/or CaMKII-dependent signal transduction pathways.

Driving research in infant and children's nutrition: a perspective on industry

As part of the workshop entitled "Early Risk Determinants and Later Health Outcomes: Implications for Research Prioritization and the Food Supply" (8-9 July 2008, Washington, DC), which was cosponsored by the International Life Sciences Institute of North America and the International Life Sciences Institute Research Foundation, representatives of the food industry discussed the practical application of nutrition science. Nutrition plays a key role in guiding health outcomes throughout the life cycle. In particular, the prenatal, postnatal, and early childhood periods are extremely sensitive to the presence of appropriate nutrition. A growing body of evidence shows that early nutrition may program the unborn and the infant's key physiologic systems, including the endocrine, cardiovascular, and central nervous systems, to influence later life outcomes. While scientists in academia continue to explore the multifactorial nature of early risk determinants and later life outcomes at a mechanistic and basic science level, it is important to understand the potential of the infant and child food industries to address questions such as what factors have been noted to drive research in these sectors of the food industry. How can scientists in these industries work alongside the scientists in academia and in government to set priorities, make decisions around these health issues, and translate academic insights into innovative nutritional solutions for the benefit of public health? Given the commitment of the infant and child food industries to deliver scientifically supported early life nutrition, it is easy to understand why this industry would work in partnership with both the scientists in academia and the government to identify a means of addressing the fundamental questions of this workshop.

Prenatal nutrition: a critical window of opportunity for mother and child

The prenatal period encompasses a critical window for future health and functioning of mother and child. Attention previously focused on undernutrition risk (i.e., in developing countries and famine conditions) shifted to mismatch between prenatal 'programming' by undernutrition and postnatal overconsumption (i.e., low birthweight vs rapid postnatal growth), now to overconsumption/overweight throughout the reproductive cycle and short- and long-term health risks, including obesity, diabetes, dyslipidemia and cardiovascular disease. Moreover, overconsumption/overweight do not guarantee adequacy of critical nutrients (i.e., against birth defects or for brain development). Multinutrient supplementation - including zinc, iodine, choline and long-chain polyunsaturated fatty acids, especially n-3 - may have advantages over single-nutrient supplements, for example, iron or folate. Future nutritional care for healthy in utero programming may necessitate individual assessment and follow-up, including preconception nutritional preparation, appropriate weight gain, metabolic balance and food-based regimens enhanced by key nutrient fortification and/or supplementation, warranting further research into nutritional optimization of pregnancy outcomes.