Biology subjects

Georgieff, M. K.

Publications and source records attributed to Georgieff, M. K..

7 recordsLinked to original sources

bioRxiv2026

Hierarchical Transcriptomic and Epigenetic Recovery and Remodeling in the Developing Hippocampus Following Early-life Environmental Insults: An Iron Deficiency Rat Model

BackgroundsEarly-life environmental insults cause persistent neurodevelopmental abnormalities accompanied by transcriptional and epigenetic dysregulation despite removal of the original insult or postnatal intervention. However, transcriptomic and epigenomic responses to developmental insults and subsequent treatment during active neurodevelopment remain insufficiently characterized. Developmental iron deficiency (ID) provides a unique model for investigating this question because iron is an essential cofactor for TET DNA dioxygenases and developmental ID causes persistent behavioral and molecular alterations despite iron repletion. ResultsWe integrated the hippocampal transcriptome, DNA methylome (5mC), and hydroxymethylome (5hmC) in male rats at postnatal day 15 following developmental ID and postnatal iron treatment, using Oxford Nanopore sequencing for native DNA modification profiling. Developmental ID induced substantial transcriptional and epigenetic alterations associated with synaptic function, neurodevelopment, and neuroinflammation. Postnatal iron treatment induced a hierarchical response across molecular layers: while transcriptomic alterations largely normalized, 5mC showed only partial recovery, and 5hmC showed extensive de novo modifications. Recovered, persistent, and newly emerged epigenetic marks were associated with increasingly specialized biological functions, from broad neurodevelopmental processes to specific pathways. Furthermore, while 5mC enrichment was associated with transcriptionally suppressed pathways, 5hmC enrichment showed weaker coupling with concurrent transcriptomic activity, suggesting epigenetic poising rather than immediate transcriptional output. MergeOmics integration identified key driver genes showing post-treatment epigenetic regulation despite transcriptional recovery. ConclusionsMolecular recovery following developmental ID extends beyond transcriptomic normalization, involving persistent and extensive epigenetic remodeling. This study provides a framework for understanding molecular responses following early-life environmental insults and highlights the importance of delineating persistent regulatory reprogramming.

genomics↗

bioRxiv2025

Neonatal phlebotomy-induced anemia compromises mitochondrial bioenergetics in the developing hippocampus

BackgroundAnemia is a common medical condition in preterm infants. Previous studies show that neurodevelopmental outcomes of preterm infants are dependent in part on the degree of anemia. In a developmentally appropriately-timed neonatal mouse model, phlebotomy induced anemia (PIA) of the degree commonly seen in hospitalized preterm infants results in brain iron deficiency and hypoxia and significant short-term and long-term brain dysfunction, especially in the hippocampus. Iron and oxygen are critical for mitochondrial oxidative phosphorylation-mediated ATP production and thus energetically demanding brain developmental processes (e.g., axon/dendrite growth, myelination, synaptogenesis). ObjectiveTo test the hypothesis that neonatal PIA acutely impairs mitochondrial respiratory capacity and electron transport chain (ETC) complex function in the developing hippocampus. MethodsNeonatal mice were phlebotomized daily beginning on postnatal day 3 (P3). On P14, mitochondria were isolated from the hippocampus of male and female PIA and non-bled mice. Seahorse bioenergetic analyses were performed to determine the effects of PIA on mitochondrial oxidative phosphorylation activity and ETC complex functional capacity. ResultsPIA hippocampal mitochondria demonstrated an overall reduced oxygen consumption rate (OCR) compared to non-bled controls when ETC oxygen consumption was coupled to ATP production. PIA reduced hippocampal mitochondrial OCR that was not due to the ETC in females not males. Basal respiration, proton leak, and maximal respiratory capacity were significantly reduced in PIA hippocampal mitochondria, an effect that did not differ by sex. When mitochondrial ETC oxygen consumption was uncoupled from ATP production with the protonophore FCCP, a mild reduction in OCR was observed across all ETC complexes, with only complex I-mediated OCR being significantly lower than non-bled controls. ConclusionsThese findings suggest that impaired mitochondrial energetic capacity may mechanistically contribute to the persistent neurobehavioral deficits caused by PIA, through dysregulation of energy-demanding neurodevelopmental processes (e.g., neuron structural maturation).

developmental biology↗

bioRxiv2025

Iron Deficiency Impairs Mitochondrial Energetics and Early Axonal Growth and Branching in Developing Hippocampal Neurons

Each stage of neuronal development (i.e., proliferation, differentiation, migration, neurite outgrowth and synapse formation) requires functional and highly coordinated metabolic activity to ultimately ensure proper sculpting of complex neural networks. Energy deficits underlie many neurodevelopmental, neuropsychiatric and neurodegenerative diseases implicating mitochondria as a potential therapeutic target. Iron is necessary for neuronal energy output through its direct role in mitochondrial oxidative phosphorylation. Iron deficiency (ID) reduces mitochondrial respiratory and energy capacity in developing hippocampal neurons, causing permanently simplified dendritic arbors and impaired learning and memory. However, the effect of ID on early axonogenesis has not been explored. We used an embryonic mixed-sex primary mouse hippocampal neuron culture model of developmental ID to evaluate mitochondrial respiration and dynamics and effects on axonal morphology. At 7 days in vitro (DIV), ID impaired mitochondrial oxidative phosphorylation capacity and stunted growth of both the primary axon and branches, without affecting branch number. Mitochondrial motility was not altered by ID, suggesting that mitochondrial energy production --- not trafficking --- underlie the axon morphological deficits. These findings provide the first link between iron-dependent neuronal energy production and early axon structural development and emphasize the importance of maintaining sufficient iron during gestation to prevent the negative consequences of ID on brain health across the lifespan. Significance StatementThis study used a primary mouse hippocampal neuron culture model of iron deficiency to address how disruption of iron-regulated mitochondrial activities affects axonal development. After axon initiation but prior to rapid dendrite outgrowth, iron chelation reduced mitochondrial oxidative phosphorylation capacity and stunted the growth of the primary axon and branches but without affecting branch number. Mitochondrial motility was not altered in iron-deficient axons, indicating that reduced neuronal energetic capacity and not impaired axonal mitochondrial trafficking may underlie these morphological deficits. Many neurodevelopmental, neuropsychiatric, and neurodegenerative disorders are characterized by iron and/or mitochondrial dysregulation, highlighting the importance of advancing knowledge on the effects of mitochondrial deficits in early life as it pertains to optimizing brain health throughout the lifespan.

neuroscience↗

bioRxiv2025

Brain-derived exosome biomarkers of neuroinflammation and neuronal functional iron deficiency in newborns of overweight-obese mothers

BackgroundNon-infectious neuroinflammation (NINI) in early life and neonatal neural iron deficiency (nID) have been proposed to contribute to neurodevelopmental dysfunction and disorders, including autism, through toxic effects on neural cells and impaired molecular signaling. Early detection of NINI and nID may enable interventions to restore neurodevelopmental homeostasis and reduce long-term impact. However, such diagnoses are impossible due to ethical reason to access to the central nervous system (e.g., lumbar puncture) when there is no suspicion of brain infection (e.g., meningitis). MethodsWe refined a methodology to isolate and quantify inflammatory and iron-regulatory proteins in high-quality brain-derived extracellular vesicles (BDEVs) from human umbilical cord blood. A preclinical model was used to validate that BDEV contents reflect the brain microenvironment. We then applied this approach to evaluate biomarkers of NINI and nID in BDEVs isolated from cord plasma of newborns of mothers with obesity, a non-infectious pro-inflammatory gestational condition and a risk factor for nID. FindingsPlasma BDEV analytes correlated more strongly with brain analytes and showed stronger associations among functionally related molecules compared with whole plasma analytes. Maternal obesity induced an anti-inflammatory response in the brain compartment, a pro-inflammatory response in the periphery, and functional nID. InterpretationBDEVs may provide a more sensitive representation of the brain microenvironment than blood-based measures (e.g., plasma), enabling non-invasive, early detection of infants with NINI and neonatal nID. FundingSupported by NIH, the Masonic Institute for Developing Brain, Hennepin Healthcare Research Institute, UnityPoint Health Meriter Foundation, and American Academy of Pediatrics Resident Research Grant. Research in ContextO_ST_ABSEvidence before this studyC_ST_ABSPrevious studies hypothesized that gestational inflammatory environments (e.g., maternal obesity) increase risk of neonatal neural iron deficiency (nID), neuroinflammation, and neurodevelopmental disorders. However, assessing non-infectious neuroinflammation (NINI) in infants from these high-risk groups is not feasible or clinically justifiable using invasive methods (e.g., cerebrospinal fluid collection), and analytes from whole blood or plasma may not accurately reflect brain physiological status. Added value of this studyWe refined a protocol to isolate brain-derived extracellular vesicles (BDEVs) from a small amount of plasma sample (100 {micro}L) and characterized their contents to approximate brain physiology. We demonstrated that BDEVs more accurately reflect brain status compared with whole plasma. In newborns of mothers with obesity during pregnancy, we found evidence of a low-grade peripheral inflammation accompanied by a protective anti-inflammatory response in the brain. Maternal obesity was also found to induce neonatal nID. Implications of all the available evidenceBDEVs can serve as an accurate, non-invasive tool to assess brain condition. In clinical settings, this approach may be used for early diagnosis, monitoring disease progression, and evaluating treatment effects. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=139 SRC="FIGDIR/small/648967v2_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@108caa9org.highwire.dtl.DTLVardef@311ecdorg.highwire.dtl.DTLVardef@dd4086org.highwire.dtl.DTLVardef@1b747ea_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2023

Cellular Iron Deficiency Disrupts Thyroid Hormone Regulated Gene Expression in Developing Hippocampal Neurons

BackgroundDeveloping neurons have high thyroid hormone and iron requirements to support their metabolism and growth. Early-life iron and thyroid hormone deficiencies are prevalent, often coexist, and increase the risk of permanently impaired neurobehavioral function in children. Early-life dietary iron deficiency reduces thyroid hormone levels and impairs thyroid hormone-responsive gene expression in the neonatal rat brain. ObjectiveThis study determined whether neuronal-specific iron deficiency alters thyroid hormone-regulated gene expression in developing neurons. MethodsIron deficiency was induced in primary mouse embryonic hippocampal neuron cultures with the iron chelator deferoxamine (DFO) beginning at 3 days in vitro (DIV). At 11DIV and 18DIV, mRNA levels for thyroid hormone-regulated genes indexing thyroid hormone homeostasis (Hr, Crym, Dio2, Slco1c1, Slc16a2) and neurodevelopment (Nrgn, Pvalb, Klf9) were quantified. To assess the effect of iron repletion, DFO was removed at 14DIV from a subset of DFO-treated cultures and gene expression and ATP levels were quantified at 21DIV. ResultsAt 11DIV and 18DIV, neuronal iron deficiency decreased Nrgn, Pvalb, and Crym, and by 18DIV, Slc16a2, Slco1c1, Dio2, and Hr were increased; collectively suggesting cellular sensing of a functionally abnormal thyroid hormone state. Dimensionality reduction with Principal Component Analysis (PCA) reveals that thyroid hormone homeostatic genes strongly correlate with and predict iron status (Tfr1 mRNA). Iron repletion from 14-21DIV restored neurodevelopmental genes, but not all thyroid hormone homeostatic genes, and ATP concentrations remained significantly altered. PCA clustering suggests that cultures replete with iron maintain a gene expression signature indicative of previous iron deficiency. ConclusionsThese novel findings suggest there is an intracellular mechanism coordinating cellular iron/thyroid hormone activities. We speculate this is a part of homeostatic response to match neuronal energy production and growth signaling for these important metabolic regulators. However, iron deficiency may cause permanent deficits in thyroid hormone-dependent neurodevelopmental processes even after recovery from iron deficiency.

neuroscience↗

bioRxiv2022

Sex-Specific Effects of Early-Life Iron Deficiency and Prenatal Choline Treatment on Adult Rat Hippocampal Transcriptome

BackgroundFetal-neonatal iron deficiency (ID) causes long-term neurocognitive and affective dysfunctions. Clinical and preclinical studies have shown that early-life ID produces sex-specific effects. However, little is known about the molecular mechanisms underlying these early-life ID-induced sex-specific effects on neural gene regulation. ObjectiveTo illustrate sex-specific transcriptome alteration in adult rat hippocampus induced by fetal-neonatal ID and prenatal choline treatment. MethodsPregnant rats were fed an iron-deficient (4 mg/kg Fe) or iron-sufficient (200 mg/kg Fe) diet from gestational day (G) 2 to postnatal day (P) 7 with or without choline supplementation (5 g/kg choline) from G11-18. Hippocampi were collected from P65 offspring of both sexes and analyzed for changes in gene expression. ResultsBoth early-life ID and choline treatment induced transcriptional changes in adult female and male rat hippocampus. Both sexes showed ID-induced alterations in gene networks leading to enhanced neuroinflammation. In females, ID-induced changes indicating enhanced activity of oxidative phosphorylation and fatty acid metabolism, which are contrary to the ID effect in males. Prenatal choline supplementation induced the most robust changes in gene expression, particularly in the iron-deficient animals where it partially rescued ID-induced dysregulations. Choline supplementation also altered hippocampal transcriptome in the iron-sufficient rats with indications for both beneficial and adverse effects. ConclusionsThis study provided unbiased global assessments of gene expression regulated by iron and choline status in a sex-specific manner, with greater effects in female than male rats. Our new findings highlight potential sex-specific gene networks regulated by iron and choline status for further investigation.

neuroscience↗

bioRxiv2022

ATAC and histone H3K9me3 landscapes revealed the altered epigenome by fetal-neonatal iron deficiency in the adult male rat hippocampus

Iron deficiency during the fetal-neonatal period results in long-term neurodevelopmental impairments associated with pervasive and widespread hippocampal gene dysregulation. Globally, fetal-neonatal iron deficiency produces both long-term activation and repression of hundreds of loci in the adult rat hippocampus. Prenatal choline (a methyl donor) supplementation can partially reverse these effects, suggesting an interaction between iron and choline in regulating the hippocampal transcriptome. To gain insights into the underlying epigenetic signatures, we integrate hippocampal transcriptomes and epigenetic marks of active (transposase accessible chromatin/ATAC) and repressed (H3K9me3 enrichment) genes in adult rats that had been exposed to fetal-neonatal iron deficiency with or without prenatal choline supplementation. Rats were made iron-deficient during fetal and neonatal period by limiting maternal iron intake from gestational day (G) 2 through postnatal day (P) 7. Choline (5.5 g/kg) was given to half of the pregnant dams during G11-18. This paradigm produced four comparison groups (Iron-sufficient [IS], Iron-deficient [ID], IS+choline [ISch], and ID+choline [IDch]). Hippocampi were collected from P65 males and analyzed for changes in chromatin conformation and histone H3K9me3 enrichment. ATAC-seq results accounted for 22% and 24%, whereas H3K9me3 enrichment accounted for 1.7% and 13% of differences in ID- and IDch-altered gene expression. These epigenetic changes were annotated onto gene networks regulating synaptic structure and plasticity, neuroinflammation, and reward circuits. The low correlation between gene dysregulation and changes in ATAC or H3K9me3 signatures indicate involvements of other epigenetic modifications. This study provides a genome-wide findings of stable epigenetic changes and lays a foundation for further analyses to elucidate more fully iron-dependent epigenetic mechanisms that underlie iron deficiency, choline supplementation, and their interactions in mediating long-term neural gene dysregulation. SIGNIFICANCE STATEMENTEarly-life iron deficiency can lead to long-term neurocognitive dysfunction and persistent neural gene dysregulation, despite prompt iron replenishment, suggesting that iron deficiency results in long-term neuroepigenomic changes. This study combined RNA-seq, ATAC-seq, and ChIP-seq to provide the epigenetic basis for gene dysregulation due to fetal-neonatal iron deficiency and prenatal choline supplementation. We found that early-life iron deficiency alters epigenetic regulation of genes involved in neuronal development, cell signaling, neuroinflammation, and reward-related cognition. While choline supplementation to iron-deficient animals partially reverses these effects, it also leads to dysregulation of genes in iron-sufficient animals. The patterns of gene dysregulation were positively correlated with differences in chromatin accessibility and negatively correlated with repressive histone H3K9me3 modification. Our results indicate that these changes at the epigenetic level partially account for the long-term hippocampal gene dysregulation.

neuroscience↗