Inhibitors of choline uptake and metabolism cause developmental abnormalities in neurulating mouse embryos

Choline and Betaine Levels in Plasma Mirror Choline Intake in Very Preterm Infants

Choline is essential for cell membrane formation and methyl transfer reactions, impacting parenchymal and neurological development. It is therefore enriched via placental transfer, and fetal plasma concentrations are high. In spite of the greater needs of very low birth weight infants (VLBWI), choline content of breast milk after preterm delivery is lower (median (p25-75): 158 mg/L (61-360 mg/L) compared to term delivery (258 mg/L (142-343 mg/L)). Even preterm formula or fortified breast milk currently provide insufficient choline to achieve physiological plasma concentrations. This secondary analysis of a randomized controlled trial comparing growth of VLBWI with different levels of enteral protein supply aimed to investigate whether increased enteral choline intake results in increased plasma choline, betaine and phosphatidylcholine concentrations. We measured total choline content of breast milk from 33 mothers of 34 VLBWI. Enteral choline intake from administered breast milk, formula and fortifier was related to the respective plasma choline, betaine and phosphatidylcholine concentrations. Plasma choline and betaine levels in VLBWI correlated directly with enteral choline intake, but administered choline was insufficient to achieve physiological (fetus-like) concentrations. Hence, optimizing maternal choline status, and the choline content of milk and fortifiers, is suggested to increase plasma concentrations of choline, ameliorate the choline deficit and improve growth and long-term development of VLBWI.

Association between Maternal Choline, Fetal Brain Development, and Child Neurocognition: Systematic Review and Meta-Analysis of Human Studies

We studied associations between prenatal and early postnatal choline intake, brain development, and neurocognitive function of children. We conducted a systematic review followed by a meta-analysis and critical appraisal of human studies published from 1997 to 2021. Thirty publications were identified. The meta-analysis included 5 of 7 case-control studies studying neural tube defects (NTDs) in relation to maternal choline intakes/circulating concentrations. Low maternal choline intake/circulating concentrations were associated with a higher OR for NTDs among 1131 mothers of newborns with NTDs and 4439 control mothers (pooled estimate = 1.36; 95% CI: 1.11, 1.67). The 95% prediction intervals were 0.78, 2.36. Findings and critical evaluation of 10 publications with interventional designs showed that higher maternal choline intakes during the second half of pregnancy and early postnatal period (550 mg up to 1 g/d on top of the diet) or a child intake of 513 to 625 mg/d from supplements were safe and likely to demonstrate favorable effects on several domains of child neurocognition, such as memory, attention, and visuospatial learning versus the comparators. Findings from observational studies (n = 13) partly supported the association between maternal choline intake/serum concentrations and child neurocognition, but there was low confidence in the use of plasma choline concentrations as a choline intake marker. In conclusion, low maternal choline intakes were associated with a higher OR for NTDs. The risk could be up to 2.36-fold in some populations. Despite limitations of available trials and observational studies, higher maternal choline intake was likely to be associated with better child neurocognition/neurodevelopment. The results should be used to guide choline intake recommendations in pregnancy and lactation, especially because most young women are not achieving the reference intake of choline. This meta-analysis is registered at PROSPERO as CRD42021233790.

Enterobacter ludwigii protects DSS-induced colitis through choline-mediated immune tolerance

Commensal intestinal bacteria play key roles in regulating host immune tolerance; however, bacterial strains and related metabolites directly involved in this regulation are largely unknown. Here, using a mouse model of dextran sulfate sodium (DSS)-induced colitis combined with different antibiotic treatment, Enterobacter ludwigii, abundant in microbiota of mice treated with metronidazole, is screened out to have prophylactic and therapeutic effects on DSS-induced colitis with or without the presence of complex intestinal bacteria. E. ludwigii is found to induce CD103⁺DC and regulatory T (Treg)-mediated immune tolerance for colitis remission using in vitro and in vivo experiments. Moreover, choline, one metabolite of E. ludwigii, is identified to increase dendritic cells' (DCs) immune tolerance to promote Treg differentiation. E. ludwigii is found to induce DCs' immune tolerance ability for Treg differentiation through choline and α7nAChR-mediated retinoic acid (RA) and transforming growth factor beta (TGF-β) upregulation, resulting in protecting mice against DSS-induced colitis. This study suggests potential therapeutic approaches for inflammatory bowel diseases (IBDs).

Mild Choline Deficiency and MTHFD1 Synthetase Deficiency Interact to Increase Incidence of Developmental Delays and Defects in Mice

Folate and choline are interconnected metabolically. The MTHFD1 R653Q SNP is a risk factor for birth defects and there are concerns that choline deficiency may interact with this SNP and exacerbate health risks. 80–90% of women do not meet the Adequate Intake (AI) for choline. The objective of this study was to assess the effects of choline deficiency on maternal one-carbon metabolism and reproductive outcomes in the MTHFD1-synthetase deficient mouse (Mthfd1S), a model for MTHFD1 R653Q. Mthfd1S^+/+ and Mthfd1S^+/− females were fed control (CD) or choline-deficient diets (ChDD; 1/3 the amount of choline) before mating and during pregnancy. Embryos were evaluated for delays and defects at 10.5 days gestation. Choline metabolites were measured in the maternal liver, and total folate measured in maternal plasma and liver. ChDD significantly decreased choline, betaine, phosphocholine, and dimethylglycine in maternal liver (p < 0.05, ANOVA), and altered phosphatidylcholine metabolism. Maternal and embryonic genotype, and diet-genotype interactions had significant effects on defect incidence. Mild choline deficiency and Mthfd1S^+/− genotype alter maternal one-carbon metabolism and increase incidence of developmental defects. Further study is required to determine if low choline intakes contribute to developmental defects in humans, particularly in 653QQ women.

Habitual Choline Intakes across the Childbearing Years: A Review

Choline is an important nutrient during the first 1000 days post conception due to its roles in brain function. An increasing number of studies have measured choline intakes at the population level. We collated the evidence focusing on habitual choline intakes in the preconceptual, pregnancy, and lactation life stages. We conducted a review including studies published from 2004 to 2021. Twenty-six relevant publications were identified. After excluding studies with a high choline intake (>400 mg/day; two studies) or low choline intake (<200 mg/day; one study), average choline intake in the remaining 23 studies ranged from 233 mg/day to 383 mg/day, even with the inclusion of choline from supplements. Intakes were not higher in studies among pregnant and lactating women compared with studies in nonpregnant women. To conclude, during the childbearing years and across the globe, habitual intakes of choline from foods alone and foods and supplements combined appear to be consistently lower than the estimated adequate intakes for this target group. Urgent measures are needed to (1) improve the quality of choline data in global food composition databases, (2) encourage the reporting of choline intakes in dietary surveys, (3) raise awareness about the role(s) of choline in foetal–maternal health, and (4) consider formally advocating the use of choline supplements in women planning a pregnancy, pregnant, or lactating.

The effect of choline availability from gestation to early development on brain and retina functions and phospholipid composition in a male mouse model

OBJECTIVES

Although choline is essential for brain development and neural function, the effect of choline on retina function is not well understood. This study examined the effects of choline on neural tissues of brain and retina, and membrane phospholipid (PL) composition during fetal development.

METHODS

Pregnant C57BL/6 mice were fed one of 4 choline modified diets: i) control (Cont, 2.5g/kg), ii) choline deficient (Def, 0g/kg), iii) supplemented with choline chloride (Cho, 10g/kg) and iv) supplemented with egg phosphatidylcholine (PC, 10g/kg). At postnatal day (PD) 21, pups were weaned onto their mothers' respective diets until PD 45. Spatial memory was measured using the Morris Water Maze; retina function by electroretinogram (ERG); and PL composition with nuclear magnetic resonance spectroscopy.

RESULTS

Cho and PC supplementation enhanced cued learning and spatial memory abilities, respectively (p Def > PC > Cho, with no statistically significant alterations in cone-driven responses. There were no differences in the composition of major PLs in the brain and retina. In the brain, subclasses of ether PL, alkyl acyl- phosphatidylethanolamine (PEaa) and phosphatidylcholine (PCaa) were significantly greater among the PC supplemented group in comparison to the Def group.

DISCUSSION

These results indicate that while choline supplementation during gestation to an early developmental period is beneficial for spatial memory, contributions to retina function are minor. Assessment with a larger sample size of retinas could warrant the essentiality of choline for retina development.

Maternal Choline Supplementation Alters Basal Forebrain Cholinergic Neuron Gene Expression in the Ts65Dn Mouse Model of Down Syndrome

Down syndrome (DS), trisomy 21, is marked by intellectual disability and a premature aging profile including degeneration of the basal forebrain cholinergic neuron (BFCN) projection system, similar to Alzheimer's disease (AD). Although data indicate that perinatal maternal choline supplementation (MCS) alters the structure and function of these neurons in the Ts65Dn mouse model of DS and AD (Ts), whether MCS affects the molecular profile of vulnerable BFCNs remains unknown. We investigated the genetic signature of BFCNs obtained from Ts and disomic (2N) offspring of Ts65Dn dams maintained on a MCS diet (Ts+, 2N+) or a choline normal diet (ND) from mating until weaning, then maintained on ND until 4.4-7.5 months of age. Brains were then collected and prepared for choline acetyltransferase (ChAT) immunohistochemistry and laser capture microdissection followed by RNA extraction and custom-designed microarray analysis. Findings revealed upregulation of select transcripts in classes of genes related to the cytoskeleton (Tubb4b), AD (Cav1), cell death (Bcl2), presynaptic (Syngr1), immediate early (Fosb, Arc), G protein signaling (Gabarap, Rgs10), and cholinergic neurotransmission (Chrnb3) in Ts compared to 2N mice, which were normalized with MCS. Moreover, significant downregulation was seen in select transcripts associated with the cytoskeleton (Dync1h1), intracellular signaling (Itpka, Gng3, and Mlst8), and cell death (Ccng1) in Ts compared to 2N mice that was normalized with MCS. This study provides insight into genotype-dependent differences and the effects of MCS at the molecular level within a key vulnerable cell type in DS and AD.

Comparative disposition of dimethylaminoethanol and choline in rats and mice following oral or intravenous administration

Dimethylaminoethanol (DMAE) and its salts have been used to treat numerous disorders in humans and hence safety of its use is a concern. DMAE is a close structural analog of choline, an essential nutrient. Exposure to DMAE may affect choline uptake and synthesis. The current investigation characterizes: 1) the absorption, distribution, metabolism, and excretion (ADME) of DMAE in Wistar Han rats and B6C3F1 mice following a single gavage or intravenous (IV) administration of 10, 100 or 500 mg/kg [¹⁴C]DMAE, and 2) the ADME of [¹⁴C]choline (160 mg/kg) and the effect on its disposition following pre-treatment with DMAE (100 or 500 mg/kg). In both rats and mice, following gavage administration, DMAE was excreted in urine (16-69%) and as exhaled CO₂ (3-22%). The tissue retention was moderate (21-44%); however, the brain concentrations were low and there was no accumulation. Serum choline levels were not elevated following administration of DMAE. The DMAE metabolites in urine were DMAE N-oxide and N,N-dimethylglycine; the carcinogen, N-N-dimethylnitrosamine, was not detected. The pattern of disposition of [¹⁴C]choline following gavage administration was similar to that of [¹⁴C]DMAE. Prior treatment with DMAE had minimal effects on choline disposition. The pattern of disposition of [¹⁴C]DMAE and [¹⁴C]choline following IV administration was similar to gavage administration. There were minimal dose-, sex- or species-related effects following gavage or IV administration of [¹⁴C]DMAE or [¹⁴C]choline. Data from the current study did not support previous reports that: 1) DMAE alters choline uptake and distribution, or 2) that DMAE is converted into choline in vivo.

Quantification of Human Milk Phospholipids: the Effect of Gestational and Lactational Age on Phospholipid Composition

Human milk (HM) provides infants with macro- and micronutrients needed for growth and development. Milk phospholipids are important sources of bioactive components, such as long-chain polyunsaturated fatty acids (LC-PUFA) and choline, crucial for neural and visual development. Milk from mothers who have delivered prematurely (<37 weeks) might not meet the nutritional requirements for optimal development and growth. Using liquid chromatography tandem-mass spectrometry, 31 phospholipid (PL) species were quantified for colostrum (<5 days postpartum), transitional (≥5 days and ≤2 weeks) and mature milk (>2 weeks and ≤15 weeks) samples from mothers who had delivered preterm (n = 57) and term infants (n = 22), respectively. Both gestational age and age postpartum affected the PL composition of HM. Significantly higher concentrations (p < 0.05) of phosphatidylcholine (PC), sphingomyelin (SM) and total PL were found in preterm milk throughout lactation, as well as significantly higher concentrations (p < 0.002) of several phosphatidylethanolamine (PE), PC and SM species. Multivariate analysis revealed that PLs containing LC-PUFA contributed highly to the differences in the PL composition of preterm and term colostrum. Differences related to gestation decreased as the milk matured. Thus, gestational age may impact the PL content of colostrum, however this effect of gestation might subside in mature milk.

The delaying effect of alpha-glycerophosphocholine on senescence, transthyretin deposition, and osteoarthritis in senescence-accelerated mouse prone 8 mice

Administration of alpha-glycerophosphocholine (GPC), a choline compound in food, is expected to contribute to human health. In this study, we evaluated its effect on aging in senescence-accelerated mouse prone 8 (SAMP8) mice. Male SAMP8 mice had free access to a commercial stock diet and drinking water with or without GPC (0.07 mg/ml). Mice in the GPC group had significantly lower total senescence grading score than that of the control group at 36 weeks of age. Administration of GPC decreased the deposition of transthyretin (TTR), an amyloidogenic protein, in the brain. Aggregated TTR activated microglia and led to neuroinflammation. Thus, GPC would protect the brain by reducing TTR deposition and preventing neuroinflammation. In a histological study of knee joints, it was found that SAMP8 mice administered GPC showed decreased joint degeneration. These results suggest that GPC delays the aging process and may be a useful compound in anti-aging functional food development.

Finding the genetic mechanisms of folate deficiency and neural tube defects-Leaving no stone unturned

Neural tube defects (NTDs) occur secondary to failed closure of the neural tube between the third and fourth weeks of gestation. The worldwide incidence ranges from 0.3 to 200 per 10,000 births with the United States of American NTD incidence at around 3-6.3 per 10,000 dependent on race and socioeconomic background. Human NTD incidence has fallen by 35-50% in North America due to mandatory folic acid fortification of enriched cereal grain products since 1998. The US Food and Drug Administration has approved the folic acid fortification of corn masa flour with the goal to further reduce the incidence of NTDs, especially among individuals who are Hispanic. However, the genetic mechanisms determining who will benefit most from folate enrichment of the diet remains unclear despite volumes of literature published on studies of association of genes with functions related to folate metabolism and risk of human NTDs. The advances in omics technologies provides hypothesis-free tools to interrogate every single gene within the genome of NTD affected individuals to discover pathogenic variants and methylation targets throughout the affected genome. By identifying genes with expression regulated by presence of folate through transcriptome profiling studies, the genetic mechanisms leading to human NTDs due to folate deficiency may begin to be more efficiently revealed.

Dietary choline levels modify the effects of prenatal alcohol exposure in rats

Prenatal alcohol exposure can cause a range of physical and behavioral alterations; however, the outcome among children exposed to alcohol during pregnancy varies widely. Some of this variation may be due to nutritional factors. Indeed, higher rates of fetal alcohol spectrum disorders (FASD) are observed in countries where malnutrition is prevalent. Epidemiological studies have shown that many pregnant women throughout the world may not be consuming adequate levels of choline, an essential nutrient critical for brain development, and a methyl donor. In this study, we examined the influence of dietary choline deficiency on the severity of fetal alcohol effects. Pregnant Sprague-Dawley rats were randomly assigned to receive diets containing 40, 70, or 100% recommended choline levels. A group from each diet condition was exposed to ethanol (6.0g/kg/day) from gestational day 5 to 20 via intubation. Pair-fed and ad lib lab chow control groups were also included. Physical and behavioral development was measured in the offspring. Prenatal alcohol exposure delayed motor development, and 40% choline altered performance on the cliff avoidance task, independent of one another. However, the combination of low choline and prenatal alcohol produced the most severe impairments in development. Subjects exposed to ethanol and fed the 40% choline diet exhibited delayed eye openings, significantly fewer successes in hindlimb coordination, and were significantly overactive compared to all other groups. These data suggest that suboptimal intake of a single nutrient can exacerbate some of ethanol's teratogenic effects, a finding with important implications for the prevention of FASD.

Effects of Maternal Choline Supplementation on the Septohippocampal Cholinergic System in the Ts65Dn Mouse Model of Down Syndrome

Down syndrome (DS), caused by trisomy of chromosome 21, is marked by intellectual disability (ID) and early onset of Alzheimer's disease (AD) neuropathology including hippocampal cholinergic projection system degeneration. Here we determined the effects of age and maternal choline supplementation (MCS) on hippocampal cholinergic deficits in Ts65Dn mice compared to 2N mice sacrificed at 6-8 and 14-18 months of age. Ts65Dn mice and disomic (2N) littermates sacrificed at ages 6-8 and 14-18 mos were used for an aging study and Ts65Dn and 2N mice derived from Ts65Dn dams were maintained on either a choline-supplemented or a choline-controlled diet (conception to weaning) and examined at 14-18 mos for MCS studies. In the latter, mice were behaviorally tested on the radial arm Morris water maze (RAWM) and hippocampal tissue was examined for intensity of choline acetyltransferase (ChAT) immunoreactivity. Hippocampal ChAT activity was evaluated in a separate cohort. ChAT-positive fiber innervation was significantly higher in the hippocampus and dentate gyrus in Ts65Dn mice compared with 2N mice, independent of age or maternal diet. Similarly, hippocampal ChAT activity was significantly elevated in Ts65Dn mice compared to 2N mice, independent of maternal diet. A significant increase with age was seen in hippocampal cholinergic innervation of 2N mice, but not Ts65Dn mice. Degree of ChAT intensity correlated negatively with spatial memory ability in unsupplemented 2N and Ts65Dn mice, but positively in MCS 2N mice. The increased innervation produced by MCS appears to improve hippocampal function, making this a therapy that may be exploited for future translational approaches in human DS.

Choline Ameliorates Disease Phenotypes in Human iPSC Models of Rett Syndrome

Rett syndrome (RTT) is a postnatal neurodevelopmental disorder that primarily affects girls. Mutations in the methyl-CpG-binding protein 2 (MECP2) gene account for approximately 95 % of all RTT cases. To model RTT in vitro, we generated induced pluripotent stem cells (iPSCs) from fibroblasts of two RTT patients with different mutations (MECP2 (R306C) and MECP2 (1155Δ32)) in their MECP2 gene. We found that these iPSCs were capable of differentiating into functional neurons. Compared to control neurons, the RTT iPSC-derived cells had reduced soma size and a decreased amount of synaptic input, evident both as fewer Synapsin 1-positive puncta and a lower frequency of spontaneous excitatory postsynaptic currents. Supplementation of the culture media with choline rescued all of these defects. Choline supplementation may act through changes in the expression of choline acetyltransferase, an important enzyme in cholinergic signaling, and also through alterations in the lipid metabolite profiles of the RTT neurons. Our study elucidates the possible mechanistic pathways for the effect of choline on human RTT cell models, thereby illustrating the potential for using choline as a nutraceutical to treat RTT.

Maternal choline supplementation differentially alters the basal forebrain cholinergic system of young-adult Ts65Dn and disomic mice

Down syndrome (DS), trisomy 21, is a multifaceted condition marked by intellectual disability and early presentation of Alzheimer's disease (AD) neuropathological lesions including degeneration of the basal forebrain cholinergic neuron (BFCN) system. Although DS is diagnosable during gestation, there is no treatment option for expectant mothers or DS individuals. Using the Ts65Dn mouse model of DS that displays age-related degeneration of the BFCN system, we investigated the effects of maternal choline supplementation on the BFCN system in adult Ts65Dn mice and disomic (2N) littermates at 4.3-7.5 months of age. Ts65Dn dams were maintained on a choline-supplemented diet (5.1 g/kg choline chloride) or a control, unsupplemented diet with adequate amounts of choline (1 g/kg choline chloride) from conception until weaning of offspring; post weaning, offspring were fed the control diet. Mice were transcardially perfused with paraformaldehyde, and brains were sectioned and immunolabeled for choline acetyltransferase (ChAT) or p75-neurotrophin receptor (p75(NTR) ). BFCN number and size, the area of the regions, and the intensity of hippocampal labeling were determined. Ts65Dn-unsupplemented mice displayed region- and immunolabel-dependent increased BFCN number, larger areas, smaller BFCNs, and overall increased hippocampal ChAT intensity compared with 2N unsupplemented mice. These effects were partially normalized by maternal choline supplementation. Taken together, the results suggest a developmental imbalance in the Ts65Dn BFCN system. Early maternal-diet choline supplementation attenuates some of the genotype-dependent alterations in the BFCN system, suggesting this naturally occurring nutrient as a treatment option for pregnant mothers with knowledge that their offspring is trisomy 21.

Choline transporter-like proteins CTLs/SLC44 family as a novel molecular target for cancer therapy

Choline is essential for the synthesis of the major membrane phospholipid phosphatidylcholine (PC), the methyl donor betaine and the neurotransmitter acetylcholine (ACh). Elevated levels of choline and up-regulated choline kinase activity have been detected in various cancers. Thus, the intracellular accumulation of choline through choline transporters is the rate-limiting step in phospholipid metabolism and a prerequisite for cancer cell proliferation. Previous studies have demonstrated abnormalities in choline uptake and choline phospholipid metabolism in cancer cells using the imaging of cancer with positron emission tomography (PET) and magnetic resonance spectroscopy (MRS). The aberrant choline metabolism in cancer cells is strongly correlated with their malignant progression. Using quantitative real-time PCR, the mRNA expression of choline transporters was measured, and it was found that choline transporter-like proteins CTLs/SLC44 family are highly expressed in various cancer cell lines. Choline uptake through CTLs is associated with cell viability, and the functional inhibition of CTLs could promote apoptotic cell death. Furthermore, non-neuronal cholinergic systems that include CTLs-mediated choline transport are associated with cell proliferation and their inhibition promotes apoptotic cell death in colon cancer, small cell lung cancer and human leukemic T-cells. The identification of this new CTLs-mediated choline transport system provides a potential new target for cancer therapy.

Neural tube defects, folic acid and methylation

Neural tube defects (NTDs) are common complex congenital malformations resulting from failure of the neural tube closure during embryogenesis. It is established that folic acid supplementation decreases the prevalence of NTDs, which has led to national public health policies regarding folic acid. To date, animal studies have not provided sufficient information to establish the metabolic and/or genomic mechanism(s) underlying human folic acid responsiveness in NTDs. However, several lines of evidence suggest that not only folates but also choline, B12 and methylation metabolisms are involved in NTDs. Decreased B12 vitamin and increased total choline or homocysteine in maternal blood have been shown to be associated with increased NTDs risk. Several polymorphisms of genes involved in these pathways have also been implicated in risk of development of NTDs. This raises the question whether supplementation with B12 vitamin, betaine or other methylation donors in addition to folic acid periconceptional supplementation will further reduce NTD risk. The objective of this article is to review the role of methylation metabolism in the onset of neural tube defects.

Maternal diet supplementation with methyl donors and increased parity affect the incidence of craniofacial defects in the offspring of twisted gastrulation mutant mice

Diets rich in methyl-donating compounds, including folate, can provide protection against neural tube defects, but their role in preventing craniofacial defects is less clear. Mice deficient in Twisted gastrulation (TWSG1), an extracellular modulator of bone morphogenetic protein signaling, manifest both midline facial defects and jaw defects, allowing study of the effects of methyl donors on various craniofacial defects in an experimentally tractable animal model. The goal of this study was to examine the effects of maternal dietary supplementation with methyl donors on the incidence and type of craniofacial defects among Twsg1(-/-) offspring. Nulliparous and primiparous female mice were fed an NIH31 standard diet (control) or a methyl donor supplemented (MDS) diet (folate, vitamin B-12, betaine, and choline). Observed defects in the pups were divided into those derived mostly from the first branchial arch (BA1) (micrognathia, agnathia, cleft palate) and midline facial defects in the holoprosencephaly spectrum (cyclopia, proboscis, and anterior truncation). In the first pregnancy, offspring of mice fed the MDS diet had lower incidence of BA1-derived defects (12.8% in MDS vs. 32.5% in control; P = 0.02) but similar incidence of midline facial defects (6.4% in MDS vs. 5.2% in control; P = 1.0). Increased maternal parity was independently associated with increased incidence of craniofacial defects after adjusting for diet (from 37.7 to 59.5% in control, P = 0.04 and from 19.1 to 45.3% in MDS, P = 0.045). In conclusion, methyl donor supplementation shows protective effects against jaw defects, but not midline facial defects, and increased parity can be a risk factor for some craniofacial defects.

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.

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.

Diet-gene interactions underlie metabolic individuality and influence brain development: implications for clinical practice derived from studies on choline metabolism

One of the underlying mechanisms for metabolic individuality is genetic variation. Single nucleotide polymorphisms (SNPs) in genes of metabolic pathways can create metabolic inefficiencies that alter the dietary requirement for, and responses to, nutrients. These SNPs can be detected using genetic profiling and the metabolic inefficiencies they cause can be detected using metabolomic profiling. Studies on the human dietary requirement for choline illustrate how useful these new approaches can be, as this requirement is influenced by SNPs in genes of choline and folate metabolism. In adults, these SNPs determine whether people develop fatty liver, liver damage and muscle damage when eating diets low in choline. Because choline is very important for fetal development, these SNPs may identify women who need to eat more choline during pregnancy. Some of the actions of choline are mediated by epigenetic mechanisms that permit 'retuning' of metabolic pathways during early life.

Disturbed one-carbon metabolism causing adverse reproductive outcomes in mice is associated with altered expression of apolipoprotein AI and inflammatory mediators PPARα, interferon-γ, and interleukin-10

Low dietary choline or deficiency of methylenetetrahydrofolate reductase (Mthfr) leads to hyperhomocysteinemia (Hhcy) and adverse reproductive outcomes. Homocysteine reduces synthesis of ApoAI, the major lipoprotein in HDL-cholesterol; ApoAI is regulated by PPARα and has antiinflammatory properties. Our aim was to determine whether pregnancy complications due to genetic or nutritional deficiencies in 1-carbon metabolism could relate to dysregulation of ApoAI and inflammatory mediators. We fed pregnant mice, with or without a deficiency of Mthfr, control or choline-deficient (ChDD) diets for 10-12 wk and examined levels of ApoAI, PPARα, IFNγ, and IL-10. ApoAI mRNA was reduced in livers of Mthfr(+/-) mice and ApoAI protein was reduced due to Mthfr deficiency or choline deficiency in liver and plasma. Placental ApoAI protein was also reduced due to Mthfr genotype or choline-deficient diet and in developmentally delayed embryos. Reduced liver PPARα expression (mRNA and protein) was observed in ChDD-fed mice and was associated with increased methylation of a CpG dinucleotide in its promoter. Hepatic IFNγ increased due to genotype, and placental IFNγ was higher in Mthfr(+/-) ChDD-fed dams compared to Mthfr(+/+) mice fed ChDD or Mthfr(+/-) mice fed CD. IL-10 was reduced in livers of ChDD-fed mice. We propose that a deficiency of dietary choline or Mthfr leads to Hhcy and reduced expression of maternal ApoAI, with reduced ApoAI transfer to embryo. Disturbances in 1-carbon metabolism also reduce maternal PPARα expression, possibly through promoter hypermethylation, and increase IFNγ and decrease IL-10 levels. This disturbance of the T helper (Th1) (IFNγ):Th2 (IL-10) ratio and the increase in inflammatory mediators may contribute to pregnancy complications.

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.

Dietary folate, but not choline, modifies neural tube defect risk in Shmt1 knockout mice

BACKGROUND

Low dietary choline intake has been proposed to increase the risk of neural tube defects (NTDs) in human populations. Mice with reduced Shmt1 expression exhibit a higher frequency of NTDs when placed on a folate- and choline-deficient diet and may represent a model of human NTDs. The individual contribution of dietary folate and choline deficiency to NTD incidence in this mouse model is not known.

OBJECTIVE

To dissociate the effects of dietary folate and choline deficiency on Shmt1-related NTD sensitivity, we determined NTD incidence in embryos from Shmt1-null dams fed diets deficient in either folate or choline.

DESIGN

Shmt1(+/+) and Shmt1(-/-) dams were maintained on a standard AIN93G diet (Dyets), an AIN93G diet lacking folate (FD), or an AIN93G diet lacking choline (CD). Virgin Shmt1(+/+) and Shmt1(-/-) dams were crossed with Shmt1(+/-) males, and embryos were examined for the presence of NTDs at embryonic day (E) 11.5 or E12.5.

RESULTS

Exencephaly was observed only in Shmt1(-/-) embryos isolated from dams maintained on the FD diet (P = 0.004). Approximately 33% of Shmt1(-/-)embryos (n = 18) isolated from dams maintained on the FD diet exhibited exencephaly. NTDs were not observed in any embryos isolated from dams maintained on the CD (n = 100) or control (n = 152) diets or in any Shmt1(+/+) (n = 78) or Shmt1(+/-) embryos (n = 182).

CONCLUSION

Maternal folate deficiency alone is sufficient to induce NTDs in response to embryonic Shmt1 disruption.

The nutrigenetics and nutrigenomics of the dietary requirement for choline

Advances in nutrigenetics and nutrigenomics have been instrumental in demonstrating that nutrient requirements vary among individuals. This is exemplified by studies of the nutrient choline, in which gender, single-nucleotide polymorphisms, estrogen status, and gut microbiome composition have been shown to influence its optimal intake level. Choline is an essential nutrient with a wide range of biological functions, and current studies are aimed at refining our understanding of its requirements and, importantly, on defining the molecular mechanisms that mediate its effects in instances of suboptimal dietary intake. This chapter introduces the reader to challenges in developing individual nutrition recommendations, the biological function of choline, current and future research paradigms to fully understand the consequences of inadequate choline nutrition, and some forward thinking about the potential for individualized nutrition recommendations to become a tangible application for improved health.

The supply of choline is important for fetal progenitor cells

Fetal progenitor cells proliferate, migrate, differentiate and undergo apoptosis at specific times during fetal development. Choline is needed by these cells for membrane synthesis and for methylation. There is growing evidence that this nutrient also modulates epigenetic regulation of gene expression in both neuronal and endothelial progenitor cells, thereby modifying brain development. It is likely that these mechanisms explain why, in rodent models, maternal dietary intake of choline influences both angiogenesis and neurogenesis in fetal hippocampus, and results in life-long changes in memory function. This also may explain why women eating diets low in choline have a greater risk of having a baby with a birth defect. Choline is mainly found in foods that contain fat and cholesterol, and intake of such foods has diminished in response dietary advice from nutritionists and physicians. Forty years ago, diets commonly contained choline-rich foods but now women in the USA tend to eat diets low in choline content. Premenopausal women normally may require less choline in their diet than do men and postmenopausal women, because estrogen induces the gene for the enzyme catalyzing endogenous biosynthesis of the choline-containing phospholipid phosphatidylcholine. However, many women have a single nucleotide polymorphism (SNP) that blocks the induction of endogenous biosynthesis, thereby making them require more dietary choline. When these women eat diets low in choline, the supply of this nutrient to the fetus is likely to be inadequate, and may perturb progenitor cell proliferation, migration, differentiation and apoptosis.

What choline metabolism can tell us about the underlying mechanisms of fetal alcohol spectrum disorders

The consequences of fetal exposure to alcohol are very diverse and the likely molecular mechanisms involved must be able to explain how so many developmental processes could go awry. If pregnant rat dams are fed alcohol, their pups develop abnormalities characteristic of fetal alcohol spectrum disorders (FASD), but if these rat dams were also treated with choline, the effects from ethanol were attenuated in their pups. Choline is an essential nutrient in humans, and is an important methyl group donor. Alcohol exposure disturbs the metabolism of choline and other methyl donors. Availability of choline during gestation directly influences epigenetic marks on DNA and histones, and alters gene expression needed for normal neural and endothelial progenitor cell proliferation. Maternal diets low in choline alter development of the mouse hippocampus, and decrement memory for life. Women eating low-choline diets have an increased risk of having an infant with a neural tube or orofacial cleft birth defect. Thus, the varied effects of choline could affect the expression of FASD, and studies on choline might shed some light on the underlying molecular mechanisms responsible for FASD.

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.

Pre- and postnatal health: evidence of increased choline needs

Choline, a micronutrient found in food, serves as the starting material for several important metabolites that play key roles in fetal development, particularly the brain. Although human beings' requirement for choline is unknown, an Adequate Intake level of 425 mg/day was established for women with upward adjustments to 450 and 550 mg/day during pregnancy and lactation, respectively. The importance of choline in human development is supported by observations that a human fetus receives a large supply of choline during gestation; pregnancy causes depletion of hepatic choline pools in rats consuming a normal diet; human neonates are born with blood levels that are three times higher than maternal blood concentrations; and large amounts of choline are present in human milk. The development of the central nervous system is particularly sensitive to choline availability with evidence of effects on neural tube closure and cognition. Existing data show that the majority of pregnant (and presumably lactating) women are not achieving the target intake levels and that certain common genetic variants may increase requirements for choline beyond current recommendations. Because choline is not found in most varieties of prenatal vitamins (or regular multivitamins), increased consumption of choline-rich foods may be needed to meet the high pre- and postnatal demands for choline.

Low dietary choline and low dietary riboflavin during pregnancy influence reproductive outcomes and heart development in mice

BACKGROUND

Embryonic development may be compromised by dietary and genetic disruptions in folate metabolism because of the critical role of folate in homocysteine metabolism, methylation, and nucleotide synthesis. Methylenetetrahydrofolate reductase (MTHFR), choline, and riboflavin play distinct roles in homocysteine detoxification and generation of one-carbon donors for methylation. The effect of low dietary choline and riboflavin on pregnancy complications and heart development has not been adequately addressed.

OBJECTIVE

Our goal was to determine whether dietary deficiencies of choline and riboflavin in pregnant mice, with and without mild MTHFR deficiency, affect embryonic development.

DESIGN

Female Mthfr(+/+) and Mthfr(+/-) mice were fed a control diet (CD), a choline-deficient diet (ChDD), or a riboflavin-deficient diet (RbDD) and were then mated with male Mthfr(+/-) mice. Embryos were collected 14.5 d postcoitum and examined for reproductive outcomes and cardiac defects.

RESULTS

Plasma homocysteine was higher in ChDD- than in CD-fed females. Liver MTHFR enzyme activity was greater in ChDD-fed Mthfr(+/+) than in CD-fed Mthfr(+/+) females. The RbDD resulted in a higher percentage of delayed embryos and smaller embryos than did the CD. There were more heart defects, which were all ventricular septal defects, in embryos from the ChDD- and RbDD-fed females than from the CD-fed females. Dietary riboflavin and MTHFR deficiency resulted in decreased left ventricular wall thickness in embryonic hearts compared with embryos from CD-fed Mthfr(+/+) females.

CONCLUSIONS

Low dietary choline and riboflavin affect embryonic growth and cardiac development in mice. Adequate choline and riboflavin may also play a role in the prevention of these pregnancy complications 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.

Choline and risk of neural tube defects in a folate-fortified population

BACKGROUND

Folic acid is known to reduce risk of neural tube defects (NTDs). Even so, NTDs continue to occur despite individual supplementation or population fortification with folic acid. We investigated other nutrients related to one-carbon metabolism that may affect NTD risk.

METHODS

This prospective study included data from more than 180,000 pregnant women in California from 2003 through 2005. Midpregnancy serum specimens were linked with delivery information regarding the presence of a NTD, another structural malformation, or no malformation in the fetus. We identified 80 NTD-affected pregnancies (cases) and we randomly selected 409 pregnancy controls. Serum specimens were tested for methylmalonic acid, homocysteine, cysteine, methionine, total choline, betaine, cystathionine, vitamin B6, folate, vitamin B12, riboflavin, and creatinine.

RESULTS

We observed elevated NTD risks associated with lower levels of total choline, and reduced risks with higher levels of choline. Specifically, we observed an odds ratio of 2.4 (95% confidence interval = 1.3-4.7) associated with the lowest decile and an odds ratio of 0.14 (0.02-1.0) associated with the highest decile, both relative to the 25th-74th percentiles of the control distribution. These data did not show meaningful differences between cases and controls for any other analytes.

CONCLUSIONS

This is the first study to investigate total choline in NTD-affected pregnancies. Our findings for choline, for which low levels were a risk factor and higher levels were a protective factor for NTDs, may offer a useful clue toward understanding the complex etiologies of NTDs in an era of folic acid fortification of the food supply.

Nested case-control study of one-carbon metabolites in mid-pregnancy and risks of cleft lip with and without cleft palate

Evidence exists for an association between use of vitamin supplements with folic acid in early pregnancy and reduced risk for offspring with cleft lip with/without cleft palate (CLP). A few observations have been made about nutrients related to one-carbon metabolism other than folate. Our prospective study attempted to extend information on nutrition and CLP by measuring nutrient analytes in mid-pregnancy sera. This study included data from a repository of women's mid-pregnancy serum specimens collected in California from 2003-04. Each woman's specimen was linked with delivery information to determine whether her fetus had CLP or another structural malformation, or was nonmalformed. We identified 89 CLP cases. We randomly selected 409 specimens as controls. Specimens were tested for homocysteine, methylmalonic acid, folate, vitamin B12, pyridoxal phosphate, pyridoxal, pyridoxic acid, riboflavin, choline, betaine, methionine, methionine sulfoxide, cysteine, cystathionine, arginine, and asymmetric and symmetric dimethylarginine. We observed three analytes with odds ratios unlikely to be explained by random variation, i.e., elevated CLP risks were observed for low levels and for high levels of pyridoxal phosphate (vitamin B6), higher levels of choline, and low levels of symmetric dimethylarginine. These data did not show meaningful differences between cases and controls for any other analytes.

Choline deficiency alters global histone methylation and epigenetic marking at the Re1 site of the calbindin 1 gene

Maternal choline availability is essential for fetal neurogenesis. Choline deprivation (CD) causes hypomethylation of specific CpG islands in genes controlling cell cycling in fetal hippocampus. We now report that, in C57BL/6 mice, CD during gestational days 12-17 also altered methylation of the histone H3 in E17 fetal hippocampi. In the ventricular and subventricular zones, monomethyl-lysine 9 of H3 (H3K9me1) was decreased by 25% (P<0.01), and in the pyramidal layer, dimethyl-lysine 9 of H3 (H3K9me2) was decreased by 37% (P<0.05). These changes were region specific and were not observed in whole-brain preparations. Also, the same effects of CD on H3 methylation were observed in E14 neural progenitor cells (NPCs) in culture. Changes in G9a histone methyltransferase might mediate altered H3K9me2,1. Gene expression of G9a was decreased by 80% in CD NPCs (P<0.001). In CD, H3 was hypomethylated upstream of the RE1 binding site in the calbindin 1 promoter, and 1 CpG site within the calbindin1 promoter was hypermethylated. REST binding to RE1 (recruits G9a) was decreased by 45% (P<0.01) in CD. These changes resulted in increased expression of calbindin 1 in CD (260%; P<0.05). Thus, CD modulates histone methylation in NPCs, and this could underlie the observed changes in neurogenesis.

Combined thirty-day exposure to thioacetamide and choline-deprivation alters serum antioxidant status and crucial brain enzyme activities in adult rats

Choline (Ch) is an essential nutrient that seems to be involved in a wide variety of metabolic reactions and functions that affect the nervous system, while thioacetamide (TAA) is a well-known hepatotoxic agent. The induction of prolonged Ch-deprivation (CD) in rats receiving TAA (through the drinking water) provides an experimental model of mild progressive hepatotoxicity that could simulate commonly-presented cases in clinical practice. In this respect, the aim of this study was to investigate the effects of a 30-day dietary CD and/or TAA administration (300 mg/L of drinking water) on the serum total antioxidant status (TAS) and the activities of brain acetylcholinesterase (AChE), Na(+),K(+)-ATPase and Mg(2+)-ATPase of adult rats. Twenty male Wistar rats were divided into four groups: A (control), B (CD), C (TAA), D (CD+TAA). Dietary CD was provoked through the administration of Ch-deficient diet. Rats were sacrificed by decapitation at the end of the 30-day experimental period and whole brain enzymes were determined spectrophotometrically. Serum TAS was found significantly lowered by CD (-11% vs Control, p < 0.01) and CD+TAA administration (-19% vs Control, p < 0.001), but was not significantly altered due to TAA administration. The rat brain AChE activity was found significantly increased by TAA administration (+11% vs Control, p < 0.01), as well as by CD+TAA administration (+14% vs Control, p < 0.01). However, AChE was not found to be significantly altered by the 30-day dietary CD. On the other hand, CD caused a significant increase in brain Na(+),K(+)-ATPase activity (+16% vs Control, p < 0.05) and had no significant effect on Mg(2+)-ATPase. Exposure to TAA had no significant effect on Na(+),K(+)-ATPase, but inhibited Mg(2+)-ATPase (-20% vs Control, p < 0.05). When administered to CD rats, TAA caused a significant decrease in Na(+),K(+)-ATPase activity (-41% vs Control, p < 0.001), but Mg(2+)-ATPase activity was maintained into control levels. Our data revealed that an adult-onset 30-day dietary-induced CD had no effect on AChE activity. Treatment with TAA not only reversed the stimulatory effect of CD on adult rat brain Na(+),K(+)-ATPase, but caused a dramatic decrease in its activity (-41%). Previous studies have linked this inhibition with metabolic phenomena related to TAA-induced fulminant hepatic failure and encephalopathy. Our data suggest that CD (at least under the examined 30-day period) is an unfavorable background for the effect of TAA-induced hepatic damage on Na(+),K(+)-ATPase activity (an enzyme involved in neuronal excitability, metabolic energy production and neurotransmission).

Prenatal choline supplementation mitigates the adverse effects of prenatal alcohol exposure on development in rats

Prenatal alcohol exposure can lead to a range of physical, neurological, and behavioral alterations referred to as fetal alcohol spectrum disorders (FASD). Variability in outcome observed among children with FASD is likely related to various pre- and postnatal factors, including nutritional variables. Choline is an essential nutrient that influences brain and behavioral development. Recent animal research indicates that prenatal choline supplementation leads to long-lasting cognitive enhancement, as well as changes in brain morphology, electrophysiology and neurochemistry. The present study examined whether choline supplementation during ethanol exposure effectively reduces fetal alcohol effects. Pregnant dams were exposed to 6.0g/kg/day ethanol via intubation from gestational days (GD) 5-20; pair-fed and lab chow controls were included. During treatment, subjects from each group received choline chloride (250mg/kg/day) or vehicle. Physical development and behavioral development (righting reflex, geotactic reflex, cliff avoidance, reflex suspension and hindlimb coordination) were examined. Subjects prenatally exposed to alcohol exhibited reduced birth weight and brain weight, delays in eye opening and incisor emergence, and alterations in the development of all behaviors. Choline supplementation significantly attenuated ethanol's effects on birth and brain weight, incisor emergence, and most behavioral measures. In fact, behavioral performance of ethanol-exposed subjects treated with choline did not differ from that of controls. Importantly, choline supplementation did not influence peak blood alcohol level or metabolism, indicating that choline's effects were not due to differential alcohol exposure. These data indicate early dietary supplements may reduce the severity of some fetal alcohol effects, findings with important implications for children of women who drink alcohol during pregnancy.

Nutrient pathways and neural tube defects: a semi-Bayesian hierarchical analysis

BACKGROUND

We used conventional and hierarchical logistic regression to examine the association of neural tube defects (NTDs) with intake of 26 nutrients that contribute to the mechanistic pathways of methylation, glycemic control, and oxidative stress, all of which have been implicated in NTD etiology. The hierarchical approach produces more plausible, more stable estimates than the conventional approach, while adjusting for potential confounding by other nutrients.

METHODS

Analyses included 386 cases and 408 nonmalformed controls with complete data on nutrients and potential confounders (race/ethnicity, education, obesity, and intake of vitamin supplements) from a population-based case-control study of deliveries in California from 1989 to 1991. Nutrients were specified as continuous, and their units were standardized to have a mean of zero and standard deviation (SD) of 1 for comparability of units across pathways. ORs reflect a 1-SD increase in the corresponding nutrient.

RESULTS

Among women who took vitamin supplements, semi-Bayesian hierarchical modeling results suggested no associations between nutrient intake and NTDs. Among women who did not take supplements, both conventional and hierarchical models (HM) suggested an inverse association between lutein intake and NTD risk (HM odds ratio [OR] = 0.6; 95% confidence interval = 0.5-0.9) and a positive association with sucrose (HM OR 1.4; 1.1-1.8) and glycemic index (HM OR 1.3; 1.0-1.6).

CONCLUSIONS

Our findings for lutein, glycemic index, and sucrose suggest that further study of NTDs and the glycemic control and oxidative stress pathways is warranted.

The solute carrier 44A1 is a mitochondrial protein and mediates choline transport

Choline oxidation to betaine takes place in the mitochondria; however, a protein regulating mitochondrial choline transport was never identified. The purpose of this study was to analyze subcellular localization of the solute carrier 44A1 (SLC44A1), a plasma membrane choline transporter sensitive to inhibition by hemicholinium-3. We generated N- and C-terminal-SLC44A1-specific antibodies and analyzed localization of endogenous and overexpressed SLC44A1 in C2C12 mouse muscle cells, MCF7 human breast cancer cells, and mouse tissues using confocal microscopy, differential centrifugation, and Western blotting. We further performed choline uptake competition studies on isolated mitochondria using the specific inhibitor hemicholinium-3 and SLC44A1 antibodies, and analyzed mitochondria of FL83B hepatocytes after the targeted knock-down of SLC44A1 using siRNA technology. In addition, we analyzed SLC44A1 expression during choline deficiency. Localization studies revealed plasma membrane, cytosolic, microsomal, and mitochondrial localization of endogenous and His-tagged SLC44A1. Uptake studies in isolated mitochondria show an accumulation of (3)H-choline, which is strongly inhibited by hemicholinium-3 (60%), by an excess of unlabeled choline (97%), and by both SLC44A1 antibodies. SLC44A1 mRNA and protein expression were down-regulated during choline deficiency. These data clearly establish SLC44A1 as an important mediator of choline transport across both the plasma membrane and the mitochondrial membrane.

Importance of methyl donors during reproduction

Evidence is growing that optimal dietary intake of folate and choline (both involved in one-carbon transfer or methylation) is important for successful completion of fetal development. Significant portions of the population are eating diets low in one or both of these nutrients. Folates are important for normal neural tube closure in early gestation, and the efficacy of diet fortification with folic acid in reducing the incidence of neural tube defects is a major success story for public health nutrition. Similarly, maternal dietary choline is important for normal neural tube closure in the fetus and, later in gestation, for neurogenesis in the fetal hippocampus, with effects on memory that persist in adult offspring; higher choline intake is associated with enhanced memory performance. Although both folates and choline have many potentially independent mechanisms whereby they could influence fetal development, these 2 nutrients also have a common mechanism for action: altered methylation and related epigenetic effects on gene expression.

Genetic polymorphisms in methyl-group metabolism and epigenetics: lessons from humans and mouse models

Choline is an essential nutrient that is critical during fetal brain development. Choline deficiency, through disturbing methyl metabolism, may alter DNA methylation and thereby influence neural precursor cell proliferation and apoptosis. This results in long term alterations in brain structure and function, specifically memory function. A recommended dietary intake for choline in humans was set in 1998, and a portion of the choline requirement can be met via endogenous de novo synthesis of phosphatidylcholine catalyzed by phosphatidylethanolamine N-methyltransferase (PEMT) in the liver. Though many foods contain choline, many humans do not get enough in their diets. When deprived of dietary choline, most adult men and postmenopausal women developed signs of organ dysfunction (fatty liver, liver or muscle cell damage). However, only a portion of premenopausal women developed such problems. The difference in requirement occurs because estrogen induces expression of the PEMT gene and allows premenopausal women to make more of their needed choline endogenously. In addition, there is significant variation in the dietary requirement for choline that can be explained by common genetic variants (single nucleotide polymorphisms; SNPs) in genes of choline and folate metabolism. Some of these increase the risk of choline deficiency many-fold. These variations in choline requirement could have important implications for brain development.

Equilibrated diet restores the effects of early age choline-deficient feeding on rat brain antioxidant status and enzyme activities: the role of homocysteine, L-phenylalanine and L-alanine

Choline is an essential nutrient that seems to be involved in a wide variety of metabolic reactions and functions, that affect the developing brain. The aim of this study was to: (a)examine the effects of early age choline deficient diet (CDD) administration on the total antioxidant status (TAS) and the activities of acetylcholinesterase (AChE), (Na(+),K(+))-ATPase and Mg(2+)-ATPase in the rat brain, (b)investigate the effect of feeding restoration into an equilibrated diet on the above parameters, and (c)study the role of homocysteine (Hcy), L: -phenylalanine (Phe) and L: -alanine (Ala) in certain of the above effects. Male and female Wistar rats were continuously kept off choline (Ch) during their gestational period of life, as well as during the first 6 weeks of their post-gestational life. The animals were sacrificed by decapitation and their whole brains were rapidly removed and homogenated. Their enzyme activities were measured spectrophotometrically. Moreover, in vitro experiments were conducted in order to estimate the effects of Hcy (0.3 mM), Phe (1.2 mM) and/or Ala (1.2 mM) on the above parameters. The administration of CDD led to a statistically significant decrease of the rat brain TAS (-29%, p < 0.001) and to a significant increase of both AChE (+20%, p < 0.001) and (Na(+),K(+))-ATPase (+35%, p < 0.001) activities. Mg(2+)-ATPase activity was found unaltered. Equilibrated diet, administered to early age CDD-treated rats of both sexes for an additional period of 18 weeks, restored the above parameters to control levels. Moreover, the in vitro experiments showed that Hcy could simulate these changes (at least under the examined in vitro conditions), while both Phe and Ala act protectively against the CDD-induced effects on the examined rat brain enzyme activities. The effects of early age CDD-feeding on the examined parameters are proved to be reversible through restoration to equilibrated diet, while our data suggest a role for Hcy (as a causative parameter for the CDD-induced effects) and a possible protective role for Phe and Ala (in reversing the observed CDD-induced effects).

Ceramide signaling in cancer and stem cells

Most of the previous work on the sphingolipid ceramide has been devoted to its function as an apoptosis inducer. Recent studies, however, have shown that in stem cells, ceramide has additional nonapoptotic functions. In this article, ceramide signaling will be reviewed in light of 'systems interface biology': as an interconnection of sphingolipid metabolism, membrane biophysics and cell signaling. The focus will be on the metabolic interconversion of ceramide and sphingomyelin or sphingosine-1-phosphate. Lipid rafts and sphingolipid-induced protein scaffolds will be discussed as a membrane interface for lipid-controlled cell signaling. Ceramide/sphingomyelin and ceramide/sphingosine-1-phosphate-interdependent cell-signaling pathways are significant for the regulation of cell polarity, apoptosis and/or proliferation, and as novel pharmacologic targets in cancer and stem cells.

Phosphatidylethanolamine N-methyltransferase (PEMT) gene expression is induced by estrogen in human and mouse primary hepatocytes

Choline is an essential nutrient for humans, though some of the requirement can be met by endogenous synthesis catalyzed by phosphatidylethanolamine N-methyltransferase (PEMT). Premenopausal women are relatively resistant to choline deficiency compared with postmenopausal women and men. Studies in animals suggest that estrogen treatment can increase PEMT activity. In this study we investigated whether the PEMT gene is regulated by estrogen. PEMT transcription was increased in a dose-dependent manner when primary mouse and human hepatocytes were treated with 17-beta-estradiol for 24 h. This increased message was associated with an increase in protein expression and enzyme activity. In addition, we report a region that contains a perfect estrogen response element (ERE) approximately 7.5 kb from the transcription start site corresponding to transcript variants NM_007169 and NM-008819 of the human and murine PEMT genes, respectively, three imperfect EREs in evolutionarily conserved regions and multiple imperfect EREs in nonconserved regions in the putative promoter regions. We predict that both the mouse and human PEMT genes have three unique transcription start sites, which are indicative of either multiple promoters and/or alternative splicing. This study is the first to explore the underlying mechanism of why dietary requirements for choline vary with estrogen status in humans.

Effects of gestational and lactational choline deprivation on brain antioxidant status, acetylcholinesterase, (Na+,K+)- and Mg2+-ATPase activities in offspring rats

BACKGROUND

Choline plays an important role in brain development. Choline-deficient diet (CDD) is known to produce (among other effects) a decrease in acetylcholine in rat brains. The aim of our study was to investigate how CDD administration during gestation and lactation could affect total antioxidant status (TAS) and activities of acetylcholinesterase (AChE), (Na(+),K(+))- and Mg(2+)-ATPase in the brains of both male and female newborn and suckling (21-day-old) rats.

METHODS

Three different experiments were performed. Whole brains were obtained from: (a) newborn rats following gestational CDD (experiment I); (b) 21-day-old rats following gestational but not lactational CDD (experiment II); and (c) 21-day-old rats following gestational and lactational CDD (experiment III). Enzyme activities and TAS were measured spectrophotometrically.

RESULTS

In choline-deprived (CD) newborn rats, TAS and AChE and Na(+),K(+)-ATPase activities were significantly reduced by 23%, 24% and 50%, respectively, in the brains of both sexes. Gestational CDD caused only a decrease in TAS (-27%, p<0.001) in suckling rat brains in both sexes. No changes were observed for the other enzyme activities. Moreover, gestational and lactational CDD also led only to a decrease in TAS (-24%, p<0.001) in the suckling rat brains of both sexes. Mg(2+)-ATPase activities showed no changes after any of the experimental procedures.

CONCLUSIONS

Our data suggest that the lower enzyme activities in newborn CD brains were restored to normal after 21 days of either normal or CDD lactation, possibly due to novel synaptogenesis, endogenous neuroregulation, and/or to other substances acquired by lactation. The increase in homocysteine concentration due to choline deficiency reported in the literature may be the cause of the low antioxidant capacity observed in offspring rat brains. Brain Na(+),K(+)-ATPase inhibition (induced by CDD) could result in modulations of neural excitability, metabolic energy production and neurotransmission.

CHKA and PCYT1A gene polymorphisms, choline intake and spina bifida risk in a California population

BACKGROUND

Neural tube defects (NTDs) are among the most common of all human congenital defects. Over the last two decades, accumulating evidence has made it clear that periconceptional intake of folic acid can significantly reduce the risk of NTD affected pregnancies. This beneficial effect may be related to the ability of folates to donate methyl groups for critical physiological reactions. Choline is an essential nutrient and it is also a methyl donor critical for the maintenance of cell membrane integrity and methyl metabolism. Perturbations in choline metabolism in vitro have been shown to induce NTDs in mouse embryos.

METHODS

This study investigated whether single nucleotide polymorphisms (SNPs) in human choline kinase A (CHKA) gene and CTP:phosphocholine cytidylytransferase (PCYT1A) gene were risk factors for spina bifida. Fluorescence-based allelic discrimination analysis was performed for the two CHKA intronic SNPs hCV1562388 (rs7928739) and hCV1562393, and PCYT1A SNP rs939883 and rs3772109. The study population consisted of 103 infants with spina bifida and 338 non-malformed control infants who were born in selected California counties in the period 1989-1991.

RESULTS

The CHKA SNP hCV1562388 genotypes with at least one C allele were associated with a reduced risk of spina bifida (odds ratio = 0.60, 95%CI = 0.38-0.94). The PCYT1A SNP rs939883 genotype AA was associated with a twofold increased risk of spina bifida (odds ratio = 1.89, 95% CI = 0.97-3.67). These gene-only effects were not substantially modified by analytic consideration to maternal periconceptional choline intake.

CONCLUSION

Our analyses showed genotype effects of CHKA and PCYT1A genes on spina bifida risk, but did not show evidence of gene-nutrient interactions. The underlying mechanisms are yet to be resolved.