Excessive folic acid supplementation in pregnant mice impairs insulin secretion and induces the expression of genes associated with fatty liver in their offspring

Age-specific associations of RBC folate and several serum folate forms with obesity risk: NHANES 2011-2018

Background

This study aims to explore the associations between RBC folate, several serum folate forms [serum total folate, 5-methyltetrahydrofolate (5-mTHF), and unmetabolized folic acid (UMFA)], and obesity risk in middle-aged and older populations.

Methods

Data from NHANES (2011-2018) included 11,615 participants. Generalized linear models (GLMs) were applied to investigate associations of RBC folate and various serum folate forms with obesity risk after multivariable adjustment. Potential effect modifications were examined through stratified analyses and multiplicative interaction testing.

Results

Among the total sample, middle-aged, and older participants, 4578 (39.4%), 3613 (40.0%), and 965 (37.2%) were obese, respectively. A positive association between RBC folate and obesity risk was observed, with the highest risks of obesity were consistently found in the fourth quartile (≥ 1,430 nmol/L) for the middle-aged adults (OR = 1.104, 95% CI: 1.045-1.166) and the older participants (OR = 1.157, 95% CI: 1.036-1.293). A significant negative association between serum total folate levels and obesity risk in middle-aged participants, with an OR of 0.804 (95% CI: 0.773-0.835) in the highest quartile (≥ 54.2 nmol/L). Similarly, serum 5-mTHF levels were negatively associated with obesity risk, with an OR of 0.800 (95% CI: 0.772-0.830) in the highest quartile (≥ 51.2 nmol/L). Most importantly, older participants with UMFA levels in the fourth quartile (≥ 1.06 nmol/L) had a higher risk of obesity (OR, 1.056; 95% CI: 1.004-1.110) compared with those with lower UMFA levels, but this association was not found in the total participants or the middle-aged participants.

Conclusion

Significant positive relationships exist between RBC folate and obesity risk. Additionally, low serum 5-mTHF in middle-aged participants and high UMFA in older adults were associated with increased obesity risk, highlighting the importance of monitoring folate concentrations for guiding future clinical trials on folate supplementation.

Maternal serum unmetabolized folic acid concentration following multivitamin and mineral supplementation with or without folic acid after 12 weeks gestation: A randomized controlled trial

Pregnant women are advised to take folic acid (FA) supplements before conception and during the first trimester of pregnancy. Many women continue FA supplementation throughout pregnancy, and concerns have been raised about associations between excessive FA intake and adverse maternal and child health outcomes. Unmetabolized folic acid (UMFA) is found in serum after high FA intakes and is proposed as a biomarker for excessive FA intake. We aimed to determine if removing FA from prenatal micronutrient supplements after 12 weeks of pregnancy reduces serum UMFA concentrations at 36 weeks gestation. In this double-blind, randomized controlled trial conducted in South Australia, 103 women with a singleton pregnancy were randomly assigned at 12-16 weeks gestation to take a micronutrient supplement containing no FA or 800 µg/day FA from enrollment until 36 weeks gestation. Ninety women (0 µg/day FA n = 46; 800 µg/day FA n = 44) completed the study. Mean, UMFA concentration was lower in the women randomized to the 0 µg/day group compared to the 800 µg/day FA group, 0.6 ± 0.7 and 1.4 ± 2.7 nmol/L, respectively. The adjusted mean difference (95% CI) in UMFA between the groups was [-0.85 (-1.62, -0.08) nmol/L, p = 0.03]. Maternal serum and red blood cell folate concentrations were lower in the 0 µg/day FA group than in the 800 µg/day group (median 23.2 vs. 49.3 and 1335 vs. 1914 nmol/L, respectively; p < 0.001). Removing FA at 12-16 weeks gestation from prenatal micronutrient supplements reduced the concentration of UMFA at 36 weeks gestation.

High red blood cell folate is associated with an increased risk of diabetes death among a hypertensive cohort

The relationship between folate and diabetes remains inconclusive, possibly because of folate measured differentially between studies. Interference from mandatory folic acid fortification (FAF) has also been blamed. With both folate intake and circulating concentration measured, we assessed the relationship between folate and the risk of diabetes death in a hypertensive cohort established before FAF. We hypothesized that the association between folate and diabetes death is measurement dependent. We analyzed the data of 3133 hypertensive adults aged ≥19 years who participated in the Third National Health and Nutrition Examination Survey (1991-1994) and were followed up through December 31, 2010. Hazard ratios of diabetes death were estimated for participants with high (4th quarter) folate compared with those with moderate (2nd and 3rd quarters) or low (1st quarter) concentrations of folate. Dietary folate intake, total folate intake (including folate from supplements), serum, and red blood cell (RBC) folate were measured. After 42,025 person-years of follow-up, 165 diabetes deaths were recorded, and a dose-response positive association was observed between diabetes death and RBC folate. The adjusted hazard ratios of diabetes death were 1.00 (reference), 1.42 (95% CI. 1.20-1.68), and 2.21 (1.73-2.82), respectively, for hypertensive adults with low, moderate, and high RBC folate. No association was detected between diabetes death and serum folate concentration, folate intake, or either dietary intake or total intake. With minimized interference from FAF, neither dietary nor serum folate was associated with diabetes death, but elevated RBC folate was associated with a high risk of diabetes deaths among hypertensive patients.

Effect of folA gene in human breast milk-derived Limosilactobacillus reuteri on its folate biosynthesis

Introduction

Folate supplementation is crucial for the human body, and the chemically synthesized folic acid might have undesirable side effects. The use of molecular breeding methods to modify the genes related to the biosynthesis of folate by probiotics to increase folate production is currently a focus of research.

Methods

In this study, the folate-producing strain of Limosilactobacillus reuteri B1-28 was isolated from human breast milk, and the difference between B1-28 and folA gene deletion strain ΔFolA was investigated by phenotyping, in vitro probiotic evaluation, metabolism and transcriptome analysis.

Results

The results showed that the folate producted by the ΔFolA was 2-3 folds that of the B1-28. Scanning electron microscope showed that ΔFolA had rougher surface, and the acid-producing capacity (p = 0.0008) and adhesion properties (p = 0.0096) were significantly enhanced than B1-28. Transcriptomic analysis revealed that differentially expressed genes were mainly involved in three pathways, among which the biosynthesis of ribosome and aminoacyl-tRNA occurred in the key metabolic pathways. Metabolomics analysis showed that folA affected 5 metabolic pathways, involving 89 different metabolites.

Discussion

In conclusion, the editing of a key gene of folA in folate biosynthesis pathway provides a feasible pathway to improve folate biosynthesis in breast milk-derived probiotics.

Risk of Excess Maternal Folic Acid Supplementation in Offspring

Folate, also known as vitamin B9, facilitates the transfer of methyl groups among molecules, which is crucial for amino acid metabolism and nucleotide synthesis. Adequate maternal folate supplementation has been widely acknowledged for its pivotal role in promoting cell proliferation and preventing neural tube defects. However, in the post-fortification era, there has been a rising concern regarding an excess maternal intake of folic acid (FA), the synthetic form of folate. In this review, we focused on recent advancements in understanding the influence of excess maternal FA intake on offspring. For human studies, we summarized findings from clinical trials investigating the effects of periconceptional FA intake on neurodevelopment and molecular-level changes in offspring. For studies using mouse models, we compiled the impact of high maternal FA supplementation on gene expression and behavioral changes in offspring. In summary, excessive maternal folate intake could potentially have adverse effects on offspring. Overall, we highlighted concerns regarding elevated maternal folate status in the population, providing a comprehensive perspective on the potential adverse effects of excessive maternal FA supplementation on offspring.

Maternal methyl donor supplementation: A potential therapy for metabolic disorder in offspring

The prevalences of diabetes mellitus and obesity are increasing yearly and has become a serious social burden. In addition to genetic factors, environmental factors in early life development are critical in influencing the prevalence of metabolic disorders in offspring. A growing body of evidence suggests the critical role of early methyl donor intervention in offspring health. Emerging studies have shown that methyl donors can influence offspring metabolism through epigenetic modifications and changing metabolism-related genes. In this review, we focus on the role of folic acid, betaine, vitamin B12, methionine, and choline in protecting against metabolic disorders in offspring. To address the current evidence on the potential role of maternal methyl donors, we summarize clinical studies as well as experimental animal models that support the impact of maternal methyl donors on offspring metabolism and discuss the mechanisms of action that may bring about these positive effects. Given the worldwide prevalence of metabolic disorders, these findings could be utilized in clinical practice, in which methyl donor supplementation in the early life years may reverse metabolic disorders in offspring and block the harmful intergenerational effect.

Fructooligosaccharide feeding during gestation to pregnant mice provided excessive folic acid decreases maternal and female fetal oxidative stress by increasing intestinal microbe-derived hydrogen gas

Fructooligosaccharide (FOS) is fermented by intestinal microbes to generate intestinal microbe-derived hydrogen gas (IMDH). Oxidative stress increases during gestation, whereas hydrogen gas has antioxidant effects with therapeutic benefits. We have previously reported that the offspring from a pregnant, excessive folic acid mouse model (PEFAM) had abnormal glucose metabolism after growth. We hypothesized that IMDH by FOS feeding during gestation in PEFAM would suppress maternal and fetal oxidative stress. C57BL/6J mice on day 1 of gestation were divided into 3 groups and dissected at gestational day 18. The control (CONT) diet was AIN-93G containing folic acid 2 mg/kg diet; PEFAM was fed with an excessive folic acid (EFA) diet containing folic acid 40 mg/kg diet, and the EFA-FOS diet was replaced half of the sucrose in the EFA diet. Hydrogen gas concentrations in maternal livers and whole fetuses in EFA-FOS were significantly higher than those in CONT and EFA, respectively (P < .05). Maternal and fetal 8-hydroxy-2'-deoxyguanosine in EFA-FOS were not significantly different from those in the CONT group, whereas those in the EFA group were significantly increased compared with CONT and EFA-FOS (P < .05). In EFA-FOS, expression of protein and mRNA of superoxide dismutase and heme oxygenase 1 in mothers and superoxide dismutase in fetuses were not significantly different from those in CONT, whereas those in EFA were significantly increased (P < .05). The protein expression of Nrf2 in mothers and fetuses were not significantly different between EFA-FOS and CONT. Therefore, FOS feeding to PEFAM during gestation decreases maternal and fetal oxidative stress through IMDH.

Uncovering the Hidden Dangers and Molecular Mechanisms of Excess Folate: A Narrative Review

This review delves into the intricate relationship between excess folate (vitamin B9) intake, especially its synthetic form, namely, folic acid, and its implications on health and disease. While folate plays a pivotal role in the one-carbon cycle, which is essential for DNA synthesis, repair, and methylation, concerns arise about its excessive intake. The literature underscores potential deleterious effects, such as an increased risk of carcinogenesis; disruption in DNA methylation; and impacts on embryogenesis, pregnancy outcomes, neurodevelopment, and disease risk. Notably, these consequences stretch beyond the immediate effects, potentially influencing future generations through epigenetic reprogramming. The molecular mechanisms underlying these effects were examined, including altered one-carbon metabolism, the accumulation of unmetabolized folic acid, vitamin-B12-dependent mechanisms, altered methylation patterns, and interactions with critical receptors and signaling pathways. Furthermore, differences in the effects and mechanisms mediated by folic acid compared with natural folate are highlighted. Given the widespread folic acid supplementation, it is imperative to further research its optimal intake levels and the molecular pathways impacted by its excessive intake, ensuring the health and well-being of the global population.

Folic acid supplementation in a mouse model of diabetes in pregnancy alters insulin sensitivity in female mice and beta cell mass in offspring

Epidemiological studies have reported discrepant findings on the relationship between folic acid intake during pregnancy and risk for gestational diabetes mellitus (GDM). To begin to understand how folic acid impacts metabolic health during pregnancy, we determined the effects of excess folic acid supplementation (5× recommendation) on maternal and fetal offspring metabolic health. Using a mouse (female C57BL/6J) model of diet-induced diabetes in pregnancy (western diet) and control mice, we show that folic acid supplementation improved insulin sensitivity in the female mice fed the western diet and worsened insulin sensitivity in control mice. We found no unmetabolized folic acid in liver from supplemented mice suggesting the metabolic effects of folic acid supplementation are not due to unmetabolized folic acid. Male fetal (gestational day 18.5) offspring from folic acid supplemented dams (western and control) had greater beta cell mass and density than those from unsupplemented dams; this was not observed in female offspring. Differential sex-specific hepatic gene expression profiles were observed in the fetal offspring from supplemented dams but this differed between western and controls. Our findings suggest that folic acid supplementation affects insulin sensitivity in female mice, but is dependent on their metabolic phenotype and has sex-specific effects on offspring pancreas and liver.

Effects of High-dose Folic Acid Supplementation on Maternal/Child Health Outcomes: Gestational Diabetes Mellitus in Pregnancy and Insulin Resistance in Offspring

OBJECTIVES

The purpose of this study was to evaluate the effects of maternal high folic acid (FA) supplementation during pregnancy on glucose intolerance in dams and insulin resistance in offspring.

METHODS

Wistar female rats (n=18) were mated and randomly divided into 3 groups: a control group and 2 experimental groups. Three different feeding protocols were administered during pregnancy: control group, 2 mg/kg FA (recommended level FA supplementation); experimental 1 group, 5 mg/kg FA (tolerable upper intake level of FA supplementation [ULFolS]); and experimental 2 group, 40 mg/kg FA (high FA supplementation [HfolS]). All dams were fed the same FA content diet (2 mg/kg FA) during the lactation period. An oral glucose tolerance test was performed on day 16 of pregnancy. After the lactation period, body weight and food intake of 36 pups were monitored. Dams were euthanized at the end of the lactation period and half of the pups were euthanized at the end of week 7 and the others at the end of week 12. Serum FA, homocysteine, vitamin B12, insulin, glucose, interleukin-6, tumor necrosis factor-alpha, glycated hemoglobin (A1C), and adiponectin levels of mothers and pups were evaluated. The homeostatic model of insulin resistance (HOMA-IR) was used to determine insulin resistance in dams and offspring.

RESULTS

According to glucose tolerance test results of dams, blood glucose values at minutes 0, 60, 90, and 120 for the HFolS group were significantly higher compared with the control group (p<0.05). The A1C level in HFolS dams was significantly higher than in the control group (p<0.05). The mean birthweight of the pups in the HFolS group was significantly higher than that of control pups (p<0.05). HOMA-IR values for control and HFolS offspring were similar at weeks 7 and 12 and higher than in ULFolS offspring (p>0.05).

CONCLUSIONS

It was determined that high doses of FA exposure during pregnancy might be effective in the development of glucose intolerance in dams and insulin resistance in offspring in this study.

Folate inhibits lipid deposition via the autophagy pathway in chicken hepatocytes

Excessive fat deposition affects the efficiency and quality of broiler meat production. To understand the molecular mechanism underlying abdominal fat content of broiler lines under divergent selection, we have attempted multiple genetics and genomics methods previously. However, the molecular mechanism of hepatic fat deposition remains largely unknown. On broiler lines divergently selected for abdominal fat content, we performed integrated mRNA and lncRNA sequencing on liver tissues. Key genes and signaling pathways related to the biosynthesis, elongation and metabolism of fatty acids, metabolic pathways, and folate biosynthesis were revealed. Then, primary hepatocytes (sex determined) were isolated and cultured, and treatment concentrations of folate and palmitic acid were optimized. Expression profiling on primary hepatocytes treated by folate and/or palmitic acid revealed that folic acid inhibited lipid deposition in a sex-dependent way, through regulating transcriptional and protein levels of genes related to DNA methylation, lipid metabolism (mTOR/SREBP-1c/PI3K), and autophagy (LAMP2/ATG5) pathways. Taken together, folate could interfere with hepatic lipid deposition possibly through the involvement of the autophagy pathway in broilers.

High Dietary Folic Acid Intake Is Associated with Genomic Instability in Peripheral Lymphocytes of Healthy Adults

Mandatory fortification of food with synthetic folic acid (FA) was instituted in 1998 to reduce the incidence of neural tube defects. Adequate folate status is correlated with numerous health benefits. However, elevated consumption of FA is controversially associated with deleterious effects on health. We previously reported that excess FA mimicked folate depletion in a lymphoblastoid cell line. To explore the impact of FA intake from fortified food, we conducted an observational human study on 33 healthy participants aged 18-40 not taking any supplements. Food intake, anthropomorphic measurements, and blood samples were collected and analyzed. Our results show that individuals belonging to the highest tertile of folic acid intake, as well as ones with the highest folic acid to total folate intake ratio (FAR), display a significantly greater incidence of lymphocyte genomic damage. A decrease in global DNA methylation is observed in the highest tertile of FAR compared to the lowest (p = 0.055). A downward trend in the overall gene expression of select DNA repair and one carbon cycle genes (MGMT, MLH1, UNG, MTHFR, MTR) is noted with increased folate status and FA intake. These results provide supporting evidence that high consumption of FA from fortified foods can precipitate genomic instability in peripheral lymphocyte in vivo.

High Folate, Perturbed One-Carbon Metabolism and Gestational Diabetes Mellitus

Folate is a dietary micronutrient essential to one-carbon metabolism. The World Health Organisation recommends folic acid (FA) supplementation pre-conception and in early pregnancy to reduce the risk of fetal neural tube defects (NTDs). Subsequently, many countries (~92) have mandatory FA fortification policies, as well as recommendations for periconceptional FA supplementation. Mandatory fortification initiatives have been largely successful in reducing the incidence of NTDs. However, humans have limited capacity to incorporate FA into the one-carbon metabolic pathway, resulting in the increasingly ubiquitous presence of circulating unmetabolised folic acid (uFA). Excess FA intake has emerged as a risk factor in gestational diabetes mellitus (GDM). Several other one-carbon metabolism components (vitamin B12, homocysteine and choline-derived betaine) are also closely entwined with GDM risk, suggesting a role for one-carbon metabolism in GDM pathogenesis. There is growing evidence from in vitro and animal studies suggesting a role for excess FA in dysregulation of one-carbon metabolism. Specifically, high levels of FA reduce methylenetetrahydrofolate reductase (MTHFR) activity, dysregulate the balance of thymidylate synthase (TS) and methionine synthase (MTR) activity, and elevate homocysteine. High homocysteine is associated with increased oxidative stress and trophoblast apoptosis and reduced human chorionic gonadotrophin (hCG) secretion and pancreatic β-cell function. While the relationship between high FA, perturbed one-carbon metabolism and GDM pathogenesis is not yet fully understood, here we summarise the current state of knowledge. Given rising rates of GDM, now estimated to be 14% globally, and widespread FA food fortification, further research is urgently needed to elucidate the mechanisms which underpin GDM pathogenesis.

Excessive Folic Acid Mimics Folate Deficiency in Human Lymphocytes

Food fortification with synthetic folic acid (FA), along with supplementation, results in a marked increase in the population total of serum folates and unmetabolized folic acid (UMFA). Despite the success in reducing neural tube defects at birth in the intended target population (women of childbearing age), the potential deleterious effects of chronically high levels of UMFA in susceptible segments of the population require further investigation. In this study, we examine the effects of FA concentrations, ranging from depletion to supraphysiological levels, on markers of proliferation, DNA methylation, and DNA damage and repair in a human lymphoblastoid cell line (LCL). We note that both low and high levels of FA similarly impact global DNA methylation, cytome biomarkers measured through the CBMN assay, DNA damage induced by oxidative stress, and DNA base excision repair gene expression.

Changes in dietary intake improve glycemic control following a structured nutrition therapy during Ramadan in individuals with type 2 diabetes

BACKGROUND AND AIMS

It is unknown whether dietary modifications during Ramadan could influence glycemic control in diabetes. This study assessed dietary intake following structured Ramadan nutrition therapy and determined the association between changes in dietary intake and glycemic control parameters in patients with type 2 diabetes.

METHODS

This was an 8-week, parallel-group, non-randomised study of 60 type 2 diabetes patients who opted for structured Ramadan Nutrition Therapy (sRNT; n = 38) or standard care (SC; n = 22) group. The sRNT group received a structured Ramadan Nutrition Plan incorporated with diabetes-specific formula throughout the study, while SC received standard nutrition care. The 3-day food records assessed dietary intake at three-time points.

RESULTS

At baseline, dietary characteristics were comparable; both groups had macronutrient intakes within the recommended range, but inadequate intakes of fiber and 11 essential micronutrients. After 8 weeks, the sRNT group significantly reduced intakes of carbohydrate, dietary glycemic index, glycemic load, and increased percentage of total energy intake from protein, fiber, pyridoxine, vitamin C, vitamin D, calcium, and chromium compared with the SC group. In the sRNT group, compliance to diabetes-specific formula predicted changes in HbA1c (p = 0.024), while fiber intake predicted fasting plasma glucose (p = 0.035), after adjusting for age, sex, weight changes and other dietary variables.

CONCLUSION

Intakes of certain nutrients improved significantly in sRNT group after 8 weeks of receiving a structured Ramadan Nutrition Plan compared to the standard care. The structured Ramadan Nutrition Plan with the incorporation of diabetes-specific formula significantly improved glycemic control and dietary adequacy during Ramadan fasting.

Transcriptome Analysis of Effects of Folic Acid Supplement on Gene Expression in Liver of Broiler Chickens

Folic acid is a water-soluble B vitamin, and plays an important role in regulating gene expression and methylation. The liver is the major site of lipid biosynthesis in the chicken. Nevertheless, how gene expression and regulatory networks are affected by folic acid in liver of broilers are poorly understood. This paper conducted the RNA-seq technology on the liver of broilers under folic acid challenge investigation. First, 405 differentially expressed genes (DEGs), including 157 significantly upregulated and 248 downregulated, were detected between the control group (C) and the 5 mg folic acid group (M). Second, 68 upregulated DEGs and 142 downregulated DEGs were determined between C group and 10 mg folic acid group (H). Third, there were 165 upregulated genes and 179 downregulated genes between M and H groups. Of these DEGs, 903 DEGs were successfully annotated in the public databases. The functional classification based on GO and KEEGG showed that “general function prediction only” represented the largest functional classes, “cell cycle” (C vs. M; M vs. H), and “neuroactive ligand-receptor interaction” (C vs. H) were the highest unique sequences among three groups. SNP analysis indicated that numbers of C, M and H groups were 145,450, 146,131, and 123,004, respectively. Total new predicted alternative splicing events in C, M, and H groups were 9,521, 9,328, and 8,929, respectively. A protein-protein interaction (PPI) network was constructed, and the top 10 hub genes were evaluated among three groups. The results of real time PCR indicated that mRNA abundance of PPARγ and FAS in abdominal fat of M and H groups were reduced compared with the C group (P < 0.05). Ultramicroscopy results showed that folic acid could reduce lipid droplets in livers from chickens. Finally, contents of LPL, PPARγ, and FAS in abdominal fat were decreased with the folic acid supplmented diets (P < 0.01). These findings reveal the effects of folic acid supplemention on gene expression in liver of broilers, which can provide information for understanding the molecular mechanisms of folic acid regulating liver lipid metabolism.

One carbon metabolism and early development: a diet-dependent destiny

One carbon metabolism (OCM) is critical for early development, as it provides one carbon (1C) units for the biosynthesis of DNA, proteins, and lipids and epigenetic modification of the genome. Epigenetic marks established early in life can be maintained and exert lasting impacts on gene expression and functions later in life. Animal and human studies have increasingly demonstrated that prenatal 1C nutrient deficiencies impair fetal growth, neurodevelopment, and cardiometabolic parameters in childhood, while sufficient maternal 1C nutrient intake is protective against these detrimental outcomes. However, recent studies also highlight the potential risk of maternal 1C nutrient excess or imbalance in disrupting early development. Further studies are needed to delineate the dose-response relationship among prenatal 1C nutrient exposure, epigenetic modifications, and developmental outcomes.

DNA Methylation Patterning and the Regulation of Beta Cell Homeostasis

Pancreatic beta cells play a central role in regulating glucose homeostasis by secreting the hormone insulin. Failure of beta cells due to reduced function and mass and the resulting insulin insufficiency can drive the dysregulation of glycemic control, causing diabetes. Epigenetic regulation by DNA methylation is central to shaping the gene expression patterns that define the fully functional beta cell phenotype and regulate beta cell growth. Establishment of stage-specific DNA methylation guides beta cell differentiation during fetal development, while faithful restoration of these signatures during DNA replication ensures the maintenance of beta cell identity and function in postnatal life. Lineage-specific transcription factor networks interact with methylated DNA at specific genomic regions to enhance the regulatory specificity and ensure the stability of gene expression patterns. Recent genome-wide DNA methylation profiling studies comparing islets from diabetic and non-diabetic human subjects demonstrate the perturbation of beta cell DNA methylation patterns, corresponding to the dysregulation of gene expression associated with mature beta cell state in diabetes. This article will discuss the molecular underpinnings of shaping the islet DNA methylation landscape, its mechanistic role in the specification and maintenance of the functional beta cell phenotype, and its dysregulation in diabetes. We will also review recent advances in utilizing beta cell specific DNA methylation patterns for the development of biomarkers for diabetes, and targeting DNA methylation to develop translational approaches for supplementing the functional beta cell mass deficit in diabetes.

High maternal folic acid intake around conception alters mouse blastocyst lineage allocation and expression of key developmental regulatory genes

Folate, a cofactor for the supply of one-carbon groups, is required by epigenetic processes to regulate cell lineage determination during development. The intake of folic acid (FA), the synthetic form of folate, has increased significantly over the past decade, but the effects of high periconceptional FA intake on cell lineage determination in the early embryo remains unknown. Here, we investigated the effect of maternal high FA (HFA) intake on blastocyst development and expression of key regulatory genes. C57BL/6 adult female mice were fed either Control diet (1 mg FA) for 4 weeks before conception and during the preimplantation period (Con-Con); Control diet for 4 weeks preconception, followed by HFA (5 mg FA) diet during preimplantation (Con-HFA); or HFA diet for 4 weeks preconception and during preimplantation (HFA-HFA). At E3.5, blastocyst cell number, protein, and mRNA expression were measured. In HFA-HFA blastocysts, trophectoderm cell numbers and expression of CDX2, Oct-4, and Nanog were reduced compared with Con-Con blastocysts; Con-HFA blastocysts showed lower CDX2 and Oct-4 expression than Con-Con blastocysts. These findings suggest periconceptional HFA intake induces changes in key regulators of embryo morphogenesis with potential implications for subsequent development.

Epigenetics of Hepatic Insulin Resistance

Insulin resistance (IR) is largely recognized as a unifying feature that underlies metabolic dysfunction. Both lifestyle and genetic factors contribute to IR. Work from recent years has demonstrated that the epigenome may constitute an interface where different signals may converge to promote IR gene expression programs. Here, we review the current knowledge of the role of epigenetics in hepatic IR, focusing on the roles of DNA methylation and histone post-translational modifications. We discuss the broad epigenetic changes observed in the insulin resistant liver and its associated pathophysiological states and leverage on the wealth of 'omics' studies performed to discuss efforts in pinpointing specific loci that are disrupted by these changes. We envision that future studies, with increased genomic resolution and larger cohorts, will further the identification of biomarkers of early onset hepatic IR and assist the development of targeted interventions. Furthermore, there is growing evidence to suggest that persistent epigenetic marks may be acquired over prolonged exposure to disease or deleterious exposures, highlighting the need for preventative medicine and long-term lifestyle adjustments to avoid irreversible or long-term alterations in gene expression.