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Fetal iron deficiency alters the proteome of adult rat hippocampal synaptosomes.

ABSTRACT: 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.

SUBMITTER: Tran PV

PROVIDER: S-EPMC3882566 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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Fetal iron deficiency alters the proteome of adult rat hippocampal synaptosomes.

Tran Phu V PV Dakoji Srikanth S Reise Kathryn H KH Storey Kathleen K KK Georgieff Michael K MK

American journal of physiology. Regulatory, integrative and comparative physiology 20131002 11

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 iro ...[more]

PMID: 24089371

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Project description:BackgroundIron deficiency (ID) compromises the developing nervous system, including the hippocampus, resulting in later-life deficits despite iron repletion. The iron-dependent molecular changes driving these lasting deficits, and the effect of early iron repletion, are incompletely understood. Previous studies have utilized dietary models of maternal-fetal ID anemia (IDA) to address these questions; however, concurrent anemia prevents delineation of the specific role of iron.ObjectiveThe aim of the study was to isolate the effects of developmental ID on adult hippocampal gene expression and to determine if iron repletion reverses these effects in a mouse model of nonanemic hippocampal neuronal ID.MethodsNonanemic, hippocampus-specific neuronal ID was generated by using a Tet-OFF dominant negative transferrin receptor (DN-TFR1) mouse model that impairs cellular iron uptake. Hippocampal ID was reversed with doxycycline at postnatal day 21 (P21) in a subset of mice to create 2 experimental groups, chronically iron-deficient and formerly iron-deficient mice, which were compared with their respective doxycycline-treated and untreated iron-sufficient controls. RNA from adult male hippocampi was sequenced. Paired-end reads were analyzed for differential expression. Differentially expressed genes were analyzed in Ingenuity Pathway Analysis.ResultsA total of 346 genes were differentially expressed in adult, chronically iron-deficient hippocampi compared with controls. ID dysregulated genes in critical neurodevelopmental pathways, including axonal guidance, CDK5, Ephrin receptor, Rac, and Neurotrophin/Trk signaling. Iron repletion at P21 normalized adult hippocampal expression of 198 genes; however, genes involved in cAMP response element-binding protein (CREB) signaling, neurocognition, and neurologic disease remained dysregulated in adulthood.ConclusionsChronic ID during development, independent of anemia, alters the adult mouse hippocampal transcriptome. Restoring iron status during a known critical period of hippocampal neurodevelopment incompletely normalized these changes, suggesting a need for additional studies to identify the most effective timeline for iron therapy, and adjunctive treatments that can fully restore ID-induced molecular changes, particularly in human populations in whom chronic ID is endemic.

Project description:BackgroundEarly-life iron deficiency (ID) impairs hippocampal energy production. Whether there are changes in glucose transporter (GLUT) expression is not known.ObjectiveThe aim of this study was to investigate whether early-life ID and the treatment iron dose alter brain regional GLUT expression in adult rats and mice.MethodsIn Study 1, ID was induced in male and female Sprague Dawley rat pups by feeding dams a 3-mg/kg iron diet during gestation and the first postnatal week, followed by treatment using low-iron [3-10 mg/kg; formerly iron-deficient (FID)-10 group], standard-iron (40-mg/kg; FID-40 group), or high-iron (400-mg/kg; FID-400 group) diets until weaning. The control group received the 40 mg/kg iron diet. GLUT1, GLUT3, hypoxia-inducible factor (HIF)-1α, and prolyl-hydroxylase-2 (PHD2) mRNA and protein expression in the cerebral cortex, hippocampus, striatum, cerebellum, and hypothalamus were determined at adulthood. In Study 2, the role of hippocampal ID in GLUT expression was examined by comparing the Glut1, Glut3, Hif1α, and Phd2 mRNA expression in adult male and female wild-type (WT) and nonanemic hippocampal iron-deficient and iron-replete dominant negative transferrin receptor 1 (DNTfR1-/-) transgenic mice.ResultsIn Study 1, Glut1, Glut3, and Hif1α mRNA, and GLUT1 55-kDa protein expression was upregulated 20-33% in the hippocampus of the FID-10 group but not the FID-40 group, relative to the control group. Hippocampal Glut1 mRNA (-39%) and GLUT1 protein (-30%) expression was suppressed in the FID-400 group, relative to the control group. Glut1 and Glut3 mRNA expression was not altered in the other brain regions in the 3 FID groups. In Study 2, hippocampal Glut1 (+14%) and Hif1α (+147%) expression was upregulated in the iron-deficient DNTfR1-/- mice, but not in the iron-replete DNTfR1-/- mice, relative to the WT mice (P < 0.05, all).ConclusionsEarly-life ID is associated with altered hippocampal GLUT1 expression in adult rodents. The mouse study suggests that tissue ID is potentially responsible.

Project description:Major depressive disorder (MDD) is a debilitating illness that affects twice as many women than men postpuberty. This female bias is thought to be caused by greater heritability of MDD in women and increased vulnerability induced by female sex hormones. We tested this hypothesis by removing the ovaries from prepubertal Wistar Kyoto (WKY) more immobile (WMI) females, a genetic animal model of depression, and its genetically close control, the WKY less immobile (WLI). In adulthood, prepubertally ovariectomized (PrePubOVX) animals and their Sham-operated controls were tested for depression- and anxiety-like behaviors, using the routinely employed forced swim and open field tests, respectively, and RNA-sequencing was performed on their hippocampal RNA. Our results confirmed that the behavioral and hippocampal expression changes that occur after prepubertal ovariectomy are the consequences of an interaction between genetic predisposition to depressive behavior and ovarian hormone-regulated processes. Lack of ovarian hormones during and after puberty in the WLIs led to increased depression-like behavior. In WMIs, both depression- and anxiety-like behaviors worsened by prepubertal ovariectomy. The unbiased exploration of the hippocampal transcriptome identified sets of differentially expressed genes (DEGs) between the strains and treatment groups. The relatively small number of hippocampal DEGs resulting from the genetic differences between the strains confirmed the genetic relatedness of these strains. Nevertheless, the differences in DEGs between the strains in response to prepubertal ovariectomy identified different molecular processes, including the importance of glucocorticoid receptor-mediated mechanisms, that may be causative of the increased depression-like behavior in the presence or absence of genetic predisposition. This study contributes to the understanding of hormonal maturation-induced changes in affective behaviors and the hippocampal transcriptome as it relates to genetic predisposition to depression.

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Fetal iron deficiency alters the proteome of adult rat hippocampal synaptosomes.

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Fetal iron deficiency alters the proteome of adult rat hippocampal synaptosomes.

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