Fetal iron deficiency induces chromatin remodeling at the Bdnf locus in adult rat hippocampus

Fetal and subsequent early postnatal iron deficiency causes persistent impairments in cognitive and affective behaviors despite prompt postnatal iron repletion. The long-term cognitive impacts are accompanied by persistent downregulation of brain-derived neurotrophic factor (BDNF), a factor critical for hippocampal plasticity across the life span. This study determined whether early-life iron deficiency epigenetically modifies the Bdnf locus and whether dietary choline supplementation during late gestation reverses these modifications. DNA methylation and histone modifications were assessed at the Bdnf-IV promoter in the hippocampus of rats [at postnatal day (PND) 65] that were iron-deficient (ID) during the fetal-neonatal period. Iron deficiency was induced in rat pups by providing pregnant and nursing dams an ID diet (4 mg/kg Fe) from gestational day (G) 2 through PND7, after which iron deficiency was treated with an iron-sufficient (IS) diet (200 mg/kg Fe). This paradigm resulted in about 60% hippocampal iron loss on PND15 with complete recovery by PND65. For choline supplementation, pregnant rat dams were given dietary choline (5 g/kg) from G11 through G18. DNA methylation was determined by quantitative sequencing of bisulfite-treated DNA, revealing a small alteration at the Bdnf-IV promoter. Chromatin immunoprecipitation analysis showed increased HDAC1 binding accompanied by reduced binding of RNA polymerase II and USF1 at the Bdnf-IV promoter in formerly ID rats. These changes were correlated with altered histone methylations. Prenatal choline supplementation reverses these epigenetic modifications. Collectively, the findings identify epigenetic modifications as a potential mechanism to explicate the long-term repression of Bdnf following fetal and early postnatal iron deficiency.

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Iron-Dependent Mechanism of Neuronal Bdnf Suppression by Cellular Iron Deficiency

Current Developments in Nutrition ◽

10.1093/cdn/nzaa058_036 ◽

2020 ◽

Vol 4 (Supplement_2) ◽

pp. 1278-1278

Author(s):

Phu Tran ◽

Montana Beeson ◽

Michael Georgieff

Keyword(s):

Iron Deficiency ◽

Neuronal Cell ◽

Epigenetic Modifications ◽

Similar Degree ◽

Bdnf Expression ◽

In Vivo Models ◽

Iron Deficient

Abstract Objectives Iron deficiency (ID) during neural development is associated with long-term neurocognitive dysfunction. In rodent models, the cognitive deficit is associated with reduced hippocampal brain-derived neurotrophic factor (Bdnf) expression in adulthood despite early iron treatment. Since a previous study suggested a role of epigenetic modifications at the Bdnf locus, we assessed whether an iron-dependent signaling pathway from ID → HIF1α → JARID1B (Fe-containing histone demethylase) → Bdnf is responsible for Bdnf suppression in iron-deficient neurons. The objective is to determine the effect of ID on the HIF1α/JARID1B/Bdnf pathway in vitro and in vivo. Methods A hippocampal neuronal cell line HT-22 (n = 3/group) was used to assess cellular changes following deferoxamine (10 μM) induced-ID. In parallel, timed pregnant Sprague-Dawley rats were fed a purified iron deficient diet (ID, 4 mg Fe/kg) from gestational day (G)2 to through postnatal day (P)7 to induce a similar degree of neuronal ID. At P7, nursing dams where switched to a purified-iron sufficient diet (IS, 200 mg Fe/kg). Control dams were fed IS diet. Hippocampi (n = 6/group) were collected from P15 ID and IS rats. Enrichment of HIF1α, JARID1B, USF1, histone H3 methylation at the Bdnf promoter in both models was determined using ChIP-qPCR. Results were analyzed using t-test for pairwise comparison and α ≤ 0.05. Results ID increased nuclear HIF1α in HT-22 cells (P = 0.03), suggesting less hydroxylated-HIF1α due to reduced Fe-dependent prolyl hydroxylase (PHD) activity. Increased nuclear HIF1α led to increased binding and transactivation at the VEGF (positive control, P = 0.03)) and JARID1B promoters (P = 0.04), which in turns reduced Bdnf expression in HT-22 cells (P = 0.02). Similar effects were observed in iron-deficient P15 hippocampus. Conclusions This is the first evidence that ID directly regulates long-term neural gene expression through the cellular PHD/HIF1α/JARID1B pathway to induce epigenetic modifications both in vitro and in vivo models. Funding Sources 1R01NS099178.

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Dysregulation of Neuronal Genes by Fetal-Neonatal Iron Deficiency Anemia Is Associated with Altered DNA Methylation in the Rat Hippocampus

Nutrients ◽

10.3390/nu11051191 ◽

2019 ◽

Vol 11 (5) ◽

pp. 1191 ◽

Cited By ~ 5

Author(s):

Yu-Chin Lien ◽

David E Condon ◽

Michael K Georgieff ◽

Rebecca A Simmons ◽

Phu V Tran

Keyword(s):

Dna Methylation ◽

Iron Deficiency ◽

Early Life ◽

Rat Hippocampus ◽

Epigenetic Mechanism ◽

Deficiency Anemia ◽

Gene Dysregulation ◽

Iron Deficient ◽

Neuronal Genes

Early-life iron deficiency results in long-term abnormalities in cognitive function and affective behavior in adulthood. In preclinical models, these effects have been associated with long-term dysregulation of key neuronal genes. While limited evidence suggests histone methylation as an epigenetic mechanism underlying gene dysregulation, the role of DNA methylation remains unknown. To determine whether DNA methylation is a potential mechanism by which early-life iron deficiency induces gene dysregulation, we performed whole genome bisulfite sequencing to identify loci with altered DNA methylation in the postnatal day (P) 15 iron-deficient (ID) rat hippocampus, a time point at which the highest level of hippocampal iron deficiency is concurrent with peak iron demand for axonal and dendritic growth. We identified 229 differentially methylated loci and they were mapped within 108 genes. Among them, 63 and 45 genes showed significantly increased and decreased DNA methylation in the P15 ID hippocampus, respectively. To establish a correlation between differentially methylated loci and gene dysregulation, the methylome data were compared to our published P15 hippocampal transcriptome. Both datasets showed alteration of similar functional networks regulating nervous system development and cell-to-cell signaling that are critical for learning and behavior. Collectively, the present findings support a role for DNA methylation in neural gene dysregulation following early-life iron deficiency.

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Long-lasting behavioural consequences of neonatal iron deficiency in high-risk children

Proceedings of The Nutrition Society ◽

10.1017/s0029665120003018 ◽

2020 ◽

Vol 79 (OCE2) ◽

Author(s):

Elaine McCarthy ◽

Deirdre Murray ◽

Louise Kenny ◽

Jonathan Hourihane ◽

Alan Irvine ◽

...

Keyword(s):

High Risk ◽

Iron Deficiency ◽

Birth Cohort ◽

Multiple Pregnancy ◽

Cumulative Risk ◽

Total Problem ◽

Iron Deficient ◽

Infant Birth ◽

Neonatal Iron Deficiency

AbstractLittle consideration has been given to the long-term consequences of iron deficiency in new-born infants. Fetal iron accretion is compromised by multiple pregnancy complications including preterm birth, gestational diabetes mellitus and fetal growth restriction, while our work has identified increased risks from maternal lifestyle factors such as smoking and obesity for low iron stores at birth. Early-life events, including C-section delivery, also add to this cumulative risk of neonatal iron deficiency, predisposing infants to iron deficiency later in infancy and early childhood. This study aimed to investigate the effect of neonatal iron deficiency on neurological development up to 5 years of age in term-born participants of a maternal-infant birth cohort in Ireland. In the Cork BASELINE Birth Cohort, 697 maternal-infant dyads with prospectively collected lifestyle and clinical data from 15 weeks’ gestation had umbilical cord serum ferritin concentrations measured. Neurological assessments were performed at 2 (Bayley Scales of Infant Development and Child Behaviour Checklist [CBCL]) and 5 (Kaufman Brief Intelligence Test and CBCL) years of age. In the cohort, median [IQR] cord ferritin concentrations were 200.9 [139.0,265.8] μg/L; 7.5% had neonatal iron deficiency (< 76μg/L). Using the risk factors for neonatal iron deficiency that we previously identified (smoking, obesity, C-section delivery, SGA) in this cohort, as selection criteria, we conducted an a priori sensitivity analysis in 306 children. Of the 306 children identified as high-risk, 12.4% had neonatal iron deficiency. Those with neonatal iron deficiency had higher median [IQR] CBCL internal (9.0 [5.3,12.0] vs. 5.0 [3.0,10.0]), external (7.5 [4.0,14.8] vs. 5.0 [2.0,10.0]) and total problem (24.5 [15.3,40.8] vs. 16.0 [10.0,30.0], all P < 0.05) scores at 5 years compared to those without neonatal deficiency. This adverse effect was especially apparent in children of obese mothers (n = 85) who were iron deficient at birth, with a total problem score at 5 years of 42.0 [24.5,54.5] compared to 16.0 [8.8,29.3] in those not deficient (P = 0.008). Associations were robust to adjustment for confounding factors. No effect on cognition or intelligence at 2 or 5 years was observed in this cohort. This study has identified behavioural consequences of neonatal iron deficiency. Interventions targeting the fetal/neonatal period could, therefore, represent a key opportunity for prevention of iron deficiency and its associated long-term neurological consequences. A dual approach is required, comprising public health strategies targeting prevention, through improving nutrition and health in women, and the development of screening strategies for early detection of iron deficiency in new-borns.

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A clinical case of severe iron deficiency anemia in a patient with hiatal hernia

Medical alphabet ◽

10.33667/2078-5631-2021-23-104-109 ◽

2021 ◽

pp. 104-109

Author(s):

D. V. Lukanin ◽

A. A. Sokolov ◽

M. S. Klimenko

Keyword(s):

Iron Deficiency ◽

Blood Loss ◽

Hiatal Hernia ◽

Iron Deficiency Anemia ◽

Complete Recovery ◽

Deficiency Anemia ◽

Therapeutic Algorithm ◽

The Many

Among the many reasons for the development of iron deficiency anemia, chronic blood loss from Cameron ulcers, developing with hiatal hernias, is gaining increasing clinical significance. Nevertheless, doctors of various specialties still have limited knowledge about the role of this pathology in the depletion of the iron depot, the specifics of instrumental verification of the diagnosis, and the possibilities of surgical technologies in the complex treatment of patients with this disease. The described case illustrates the long-term course of severe iron deficiency anemia in a patient with hiatal hernia (type III) due to latent blood loss from Cameron ulcers. The use of a therapeutic algorithm, which included complex conservative therapy followed by laparoscopic surgery to eliminate the hiatal hernia, led to a complete recovery of the patient.

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Early Development of Parvalbumin-, Somatostatin-, and Cholecystokinin-Expressing Neurons in Rat Brain following Prenatal Immune Activation and Maternal Iron Deficiency

Developmental Neuroscience ◽

10.1159/000454677 ◽

2016 ◽

Vol 38 (5) ◽

pp. 342-353 ◽

Cited By ~ 8

Author(s):

Patricia Boksa ◽

Ying Zhang ◽

Dominique Nouel ◽

Alice Wong ◽

Tak Pan Wong

Keyword(s):

Iron Deficiency ◽

Early Development ◽

Immune Activation ◽

Brain Regions ◽

Neuron Density ◽

Ventral Subiculum ◽

Iron Deficient ◽

Medial Pfc ◽

Maternal Iron

Prenatal maternal infection and maternal iron deficiency during pregnancy are 2 early environmental insults associated with increased risk for schizophrenia in offspring. Substantial evidence suggests that abnormalities in inhibitory γ-aminobutyric acid (GABA) interneuron function, especially in the parvalbumin subtype of GABA interneuron, both developmentally and in adulthood, may contribute mechanistically to cognitive deficits and psychotic symptoms in schizophrenia. This study used a rat model to test whether prenatal immune activation with lipopolysaccharide (LPS; at gestation days, GD, 15 and 16) or maternal iron deficiency (from GD2 to postnatal day P7) or the combination of both insults alters major subtypes of GABAergic interneurons (parvalbumin, somatostatin, cholecystokinin) in brain regions relevant to schizophrenia (medial and dorsolateral prefrontal cortex [PFC], hippocampal CA1 and dentate gyrus, ventral subiculum) in offspring at P14 or P28. Prenatal LPS treatment significantly increased the density of parvalbumin-immunoreactive neurons at P14 in the medial PFC, dorsolateral PFC, and ventral subiculum of offspring born from iron-sufficient but not iron-deficient dams. Prenatal LPS also increased cholecystokinin neuron density in the medial PFC at P28, under both iron-sufficient and iron-deficient conditions. We observed a large increase in parvalbumin neuron density from P14 to P28 in the medial PFC and subiculum across all birth groups, that was not observed in other brain regions, and significant decreases in somatostatin neuron density from P14 to P28 in all brain regions examined across all birth groups, indicating differential developmental trajectories for parvalbumin and somatostatin neurons in various brain regions during this early postnatal period. Thus, it appears that the medial PFC and ventral subiculum, brain regions involved in circuitry modulating ventral tegmental dopamine and nucleus accumbens activities, may be regions vulnerable to effects of prenatal LPS on specific subpopulations of interneurons. It is known that the timing of maturation and expansion of parvalbumin neurons in early development provides threshold levels of inhibition that trigger critical periods for cortical plasticity, leading to long-term circuit consolidation. Thus, our finding of increased parvalbumin neuron density at early developmental times might suggest a mechanism by which an acute prenatal insult like LPS exposure could produce long-term changes in prefrontal cortical or subicular function.

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Fetal iron deficiency alters the proteome of adult rat hippocampal synaptosomes

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00292.2013 ◽

2013 ◽

Vol 305 (11) ◽

pp. R1297-R1306 ◽

Cited By ~ 21

Author(s):

Phu V. Tran ◽

Srikanth Dakoji ◽

Kathryn H. Reise ◽

Kathleen K. Storey ◽

Michael K. Georgieff

Keyword(s):

Iron Deficiency ◽

Pathway Analysis ◽

Protein Identification ◽

Complete Recovery ◽

Synaptic Proteins ◽

Synaptic Efficacy ◽

Absolute Quantitation ◽

Altered Expression ◽

Proteomic Approach ◽

Iron Deficient

Fetal and neonatal iron deficiency results in cognitive impairments in adulthood despite prompt postnatal iron replenishment. To systematically determine whether abnormal expression and localization of proteins that regulate adult synaptic efficacy are involved, we used a quantitative proteomic approach (isobaric tags for relative and absolute quantitation, iTRAQ) and pathway analysis to identify dysregulated proteins in hippocampal synapses of fetal iron deficiency model. Rat pups were made iron deficient (ID) from gestational day 2 through postnatal day (P) 7 by providing pregnant and nursing dams an ID diet (4 ppm Fe) after which they were rescued with an iron-sufficient diet (200 ppm Fe). This paradigm resulted in a 40% loss of brain iron at P15 with complete recovery by P56. Synaptosomes were prepared from hippocampi of the formerly iron-deficient (FID) and always iron-sufficient controls rats at P65 using a sucrose gradient method. Six replicates per group that underwent iTRAQ labeling and LC-MS/MS analysis for protein identification and comparison elucidated 331 differentially expressed proteins. Western analysis was used to confirm findings for selected proteins in the glutamate receptor signaling pathway, which regulates hippocampal synaptic plasticity, a cellular process critical for learning and memory. Bioinformatics were performed using knowledge-based Interactive Pathway Analysis. FID synaptosomes show altered expression of synaptic proteins-mediated cellular signalings, supporting persistent impacts of fetal iron deficiency on synaptic efficacy, which likely cause the cognitive dysfunction and neurobehavioral abnormalities. Importantly, the findings uncover previously unsuspected pathways, including neuronal nitric oxide synthase signaling, identifying additional mechanisms that may contribute to the long-term biobehavioral deficits.

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The role of iron in neurodevelopment: fetal iron deficiency and the developing hippocampus

Biochemical Society Transactions ◽

10.1042/bst0361267 ◽

2008 ◽

Vol 36 (6) ◽

pp. 1267-1271 ◽

Cited By ~ 72

Author(s):

Michael K. Georgieff

Keyword(s):

Energy Metabolism ◽

Iron Deficiency ◽

Iron Status ◽

Memory Function ◽

Dendritic Structure ◽

Human Infants ◽

Genomic Changes ◽

Iron Treatment ◽

Iron Deficient

Iron is a ubiquitous nutrient that is necessary for normal neurodevelopment. Gestational conditions that compromise fetal iron status include maternal iron deficiency, smoking, diabetes mellitus and hypertension. The iron-deficient neonate has altered recognition memory function and temperament while iron-deficient. The memory deficits persist even after iron repletion. Animal models demonstrate that early iron deficiency affects neuronal and glial energy metabolism, monoamine metabolism and myelination, consistent with behavioural findings in human infants. Of particular recent interest are genomic changes in transcripts coding for signal transduction, dendritic structure and energy metabolism induced by early iron deficiency that last well into adulthood in spite of iron treatment. Early iron sufficiency is critical for long-term neurological health.

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Fat mass and obesity-associated (FTO) gene epigenetic modifications in gestational diabetes: new insights and possible pathophysiological connections

Acta Diabetologica ◽

10.1007/s00592-020-01668-5 ◽

2021 ◽

Author(s):

Marica Franzago ◽

Federica Fraticelli ◽

Michele Marchioni ◽

Marta Di Nicola ◽

Francesca Di Sebastiano ◽

...

Keyword(s):

Dna Methylation ◽

Gestational Diabetes ◽

Clinical Information ◽

Epigenetic Modifications ◽

Inverse Association ◽

Metabolic Disturbances ◽

Mediterranean Diet Adherence ◽

Short And Long Term

Abstract Aims Gestational diabetes mellitus (GDM) can lead to short- and long-term complications for the child. Epigenetic alterations could contribute to explaining the metabolic disturbances associated with foetal programming. Although the role of the FTO gene remains unclear, it affects metabolic phenotypes probably mediated by epigenetic mechanisms. The aim of this study was to assess whether placental DNA epigenetic modifications at FTO promoter-associated cysteine–phosphate–guanine (CpG) sites are correlated with GDM. A secondary aim was to evaluate the association between the placental FTO DNA methylation and the maternal metabolic traits in women with and without GDM. Methods Socio-demographic characteristics, clinical parameters at the third trimester of pregnancy, Mediterranean diet adherence, and physical activity were assessed in 33 GDM women and 27 controls. Clinical information about the newborns was registered at birth. The FTO rs9939609 (T > A) was genotyped. Results No association between FTO DNA methylation and GDM was found. DNA methylation on the maternal side at the CpG1 was associated with maternal smoking in GDM (p = 0.034), and DNA methylation at the CpG3 was correlated with smoking or former smoking in controls (p = 0.023). A higher level of TGs was correlated with higher foetal placental DNA methylation at the CpG2 (p = 0.036) in GDM. An inverse association between HDL-C and maternal placental DNA methylation at the CpG3 in controls (p = 0.045) was found. An association between FTO rs9939609 and neonatal birthweight (p = 0.033) was detected. Conclusions In the awareness that the obesity pathophysiology is complex, the study adds a piece to this intricate mosaic.

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