Biology subjects

Svoboda, L. K.

Publications and source records attributed to Svoboda, L. K..

9 recordsLinked to original sources

bioRxiv2026

Exposure to p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) Perturbs Cell State and Stem Cell Markers and Induces an Epidermal Phenotype in Human Breast Cells

Breast cancer is the second leading cause of cancer deaths in U.S. women. Endocrine disruptors, such as the DDT metabolite DDE, are environmental factors linked to breast cancer risk. Emerging evidence shows that during carcinogenesis, cells reacquire stem cell traits and exhibit phenotypic plasticity. In these phenotypically plastic states, breast cells transition between phenotypes, for example, from epithelial to mesenchymal (EMT) phenotypes, or from luminal to basal. Discovering how environmental factors alter cell phenotype may be a critical step in preventing and treating breast cancer. We applied a novel high-content imaging method for the evaluation of expression of stemness and cell state markers (ALDH1A3, CD44, CD24, KRT8, and KRT14) and evaluated these markers after introducing environmentally relevant concentrations of DDE (25 nM to 25 M) to non-tumorigenic MCF10A breast epithelial cells grown in 3D anchorage independent conditions. After identifying surprisingly profound cell state alterations, including a loss of KRT8 and KRT14 expression, by 25 M DDE exposure, we used transcriptomic profiling along with pharmaceutical and genetic knockdown approaches to characterize the molecular mechanisms by which DDE exposure modulates breast epithelial cell state. Keratinization and formation of the cornified envelope were biological pathways upregulated with a maximum fold change of 360.47. We identify DLX3 as a transcription factor which is inducible by DDE exposure and is also highly upregulated in human breast cancers, reflecting a novel mechanism by which environmental exposures may promote cellular plasticity and breast carcinogenesis.

pharmacology and toxicology↗

bioRxiv2026

Lead Exposure During Differentiation Perturbs Electrophysiological Function in iPSC Derived Cardiomyocytes in a Cell Line-Dependent Manner

Lead (Pb) exposure is strongly associated with cardiovascular diseases, but the effects of developmental Pb exposure on the electrophysiological properties of human cardiomyocytes have not yet been investigated. Using human induced pluripotent stem cell (iPSC)-derived cardiomyocytes, we investigated the effects of human-relevant Pb exposure during ventricular cardiomyocyte differentiation on action potential properties and calcium dynamics in differentiated myocytes. We exposed 2 iPSC lines, from 1 male and 1 female donor, to Pb (0.5 or 5 micromolar) or control during only the first 8 days of differentiation, prior to functional maturation. Differentiation was carried out using an established protocol involving temporal modulation of Wnt signaling, followed by purification and maturation of contractile myocytes. We measured action potential properties and calcium dynamics using fluorescent dyes and optical mapping. We hypothesized that Pb exposure would adversely affect cardiomyocyte function, with effects persisting after cessation of exposure. In keeping with this hypothesis, we found significant Pb-induced changes in calcium (Ca) transients and action potential dynamics that were concentration and cell line specific and persisted well after exposure had ended. In the female cell line, beat frequency significantly increased with Pb exposure for both action potentials and Ca transients, while in the male cell line, beat frequency significantly decreased with Pb exposure for action potentials and increased for Ca transients. For voltage measurements, we observed significantly increased arrythmias with Pb exposure in both cell lines. Significant changes in repolarization and recovery time (for voltage and Ca, respectively) were present with Pb exposure in both cell lines. Gene expression of Ca transporters/channels and K channels were not affected, suggesting that persistent effects of Pb exposure on cardiomyocyte electrophysiology may occur through post-translational mechanisms. Overall, this study paves the way for future work to examine how exposure to Pb impacts long-term cardiac function through developmental programming.

pharmacology and toxicology↗

bioRxiv2026

Human-Relevant Lead Exposure During Differentiation Alters the Transcriptomic Profile of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Cardiovascular disease (CVD) etiology is strongly influenced by lead (Pb) exposure, but the underlying molecular and functional mechanisms are unclear, particularly during development. Using human induced pluripotent stem cell (iPSC) derived cardiomyocytes, we examined the effects of human-relevant Pb exposure during ventricular cardiomyocyte differentiation on transcription at several time points. We used an established protocol that temporally modulates Wnt signaling to differentiate iPSCs into contractile cardiomyocytes and exposed cells to 0.5 {micro}M, 5 {micro}M Pb, or control conditions during the first eight days of differentiation. Gene expression profiling on days 1, 2, 6, and 15 revealed significant Pb-induced changes in gene expression and dysregulation of pathways related to heart development and function, epigenetic machinery, and mitochondrial function throughout differentiation. Using BMDExpress3 modelling software, we calculated gene and biological pathway-specific best fit benchmark concentrations (BMCs) and found gene expression changes induced by Pb that were unique by day of differentiation but corresponded to a similar and human-relevant median benchmark concentration of 0.2 {micro}M for all days assessed. Overall, our findings provide evidence that transient Pb exposure during cardiomyocyte differentiation causes transcriptional changes in human cardiomyocytes that persist even after cessation of exposure, underscoring the need for further investigation into how Pb exposure may impact heart development and function.

pharmacology and toxicology↗

bioRxiv2026

Acute Exposure to Perfluorooctanoic Acid (PFOA) During Cardiomyogenesis disrupts Transcriptional and Electrophysiological Profiles in Differentiated Myocytes

The early developmental environment plays a critical role in the etiology of cardiovascular diseases (CVDs), but underlying molecular mechanisms are poorly understood. Exposure to per and polyfluoroalkyl substances (PFAS) are linked to various CVDs, but effects of developmental PFAS exposures on the human heart remain unclear. Using human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM), the objective of this study was to investigate the effects of PFAS exposure during cardiac differentiation on gene expression and function of cardiomyocytes. We exposed two hiPSC lines (one male and one female donor) to perfluorooctanoic acid (PFOA), a common and ubiquitous PFAS (0.05, 0.5, 5, 50, 100, 150, 200 M), followed by assessment of cellular number and pluripotency marker expression. PFOA exposure for 72 hours had no significant effects on hiPSC pluripotency, and modest inhibition of proliferation was observed only at the highest concentration. hiPSCs were then differentiated into ventricular cardiomyocytes in the continued presence or absence of PFOA (0, 0.5, 5, 50 M) using an established small molecules protocol. Optical mapping studies using voltage and calcium-sensitive dyes revealed dose and cell line-specific effects of PFOA on cardiomyocyte voltage and calcium dynamics that were still present 10 days after cessation of exposure. Patch clamping studies demonstrated small but significant reductions in repolarizing IKr currents with 5{micro}M PFOA exposure in cardiomyocytes from both donors. Using RNA-seq, we found that exposure to PFOA led to significant changes in transcriptional pathways related to lipids and lipoproteins in the female hiPSC-CM. In the male hiPSC-CM, we observed significant effects on developmental pathways and calcium homeostasis. Thus, we found that environmentally relevant PFOA exposure during cardiomyocyte differentiation affects the electrophysiological properties and transcriptome of hiPSC-CM even after cessation of exposure, with effects that differ by donor cell line. These findings provide direct experimental evidence that transient developmental exposure to PFOA can durably reprogram human cardiomyocyte function, supporting a developmental origin of PFAS-associated cardiovascular risk. Impact StatementThese studies demonstrate that exposure to environmentally relevant levels of PFOA during the differentiation of hiPSCs into cardiomyocytes alters cardiac gene expression and function, with effects that persist beyond cessation of exposure.

pharmacology and toxicology↗

bioRxiv2025

Environmentally Relevant Lead Exposure Alters Cell Morphology and Expression of Neural Hallmarks During SH-SY5Y Neuronal Differentiation

Lead (Pb) continues to be a public health burden, in the US and around the world, and yet the effects of historical and current exposure levels on neurogenesis are not fully understood. Here we examine the effects of a range of environmentally relevant Pb concentrations (0.16M, 1.26M, and 10M Pb) relative to control on neural differentiation in the SH-SY5Y cell model. Pb exposure began on Day 5 and continued throughout differentiation at Day 18. We assessed morphological measures related to neurogenesis at several time points during this process, including the expression of proteins key in neural differentiation ({beta}-tubulin III and GAP43), cell number and size, as well as the development of neurites. The bulk of detectable changes occurred with 10M Pb exposure, most notably that of {beta}-tubulin III and GAP43 expression. Effects with the 0.16M and 1.26M Pb exposure conditions increased as differentiation progressed, with significant reductions in cell and nuclear size as well as the number and length of neural projections by Day 18. Best benchmark concentration (BMC) analysis revealed many of these metrics to be susceptible to levels of Pb at or below historically relevant levels. This work highlights the disruption of neurite formation and protein expression as potential new mechanisms by which environmentally relevant Pb exposure impacts neurogenesis and morphology and perturb cognitive health throughout the life course.

neuroscience↗

bioRxiv2024

Environmentally Relevant Lead Exposure Impacts Gene Expression in SH-SY5Y Cells Throughout Neuronal Differentiation

Lead (Pb) causes learning and memory impairments, but the molecular effects of continuous, environmentally relevant levels of exposure on key neurodevelopmental processes are not fully characterized. Here we examine the effects of a range of environmentally relevant Pb concentrations (0.16M, 1.26M, and 10M Pb) relative to control on neural differentiation in the SH-SY5Y cell model. Pb exposure began on differentiation day 5 and was continuous for remaining days, after which we assessed the transcriptome via RNA sequencing at several time points. The bulk of detected changes in gene expression occurred with the 10M Pb condition. Interestingly, changes associated with the lower two exposures were differentiation stage-specific, with aberrant expression of several genes (e.g., COL3A1, HMOX1, and CCL2) observed during differentiation on days 9, 12, and 15 in both the 0.16M and 1.26M Pb conditions, and which disappeared by the time differentiation concluded on day 18. We observed six co-expression clusters of genes during differentiation, and 10uM Pb significantly perturbed two clusters, one involved in cell cycling and DNA repair and the other in protein synthesis. Benchmark concentration analysis identified many genes affected by levels of Pb at or below the current US standard (3.5g/dL) and these genes were enriched for pathways including stress responses, DNA repair, misfolded protein response, mitosis, and neurotransmitter production. This work highlights potential new mechanisms by which environmentally relevant concentrations of Pb impact gene expression throughout neural differentiation and result in long-lasting implications for neural health and cognition.

pharmacology and toxicology↗

bioRxiv2024

Sex-Specific Deflection of Age-Related DNA Methylation and Gene Expression in Mouse Heart by Perinatal Toxicant Exposures

BackgroundGlobal and site-specific changes in DNA methylation and gene expression are associated with cardiovascular aging and disease, but how toxicant exposures during early development influence the normal trajectory of these age-related molecular changes, and whether there are sex differences, has not yet been investigated. ObjectivesWe used an established mouse model of developmental exposures to investigate the effects of perinatal exposure to either lead (Pb) or diethylhexyl phthalate (DEHP), two ubiquitous environmental contaminants strongly associated with CVD, on age-related cardiac DNA methylation and gene expression. MethodsDams were randomly assigned to receive human physiologically relevant levels of Pb (32 ppm in water), DEHP (25 mg/kg chow), or control water and chow. Exposures started two weeks prior to mating and continued until weaning at postnatal day 21 (3 weeks of age). Approximately one male and one female offspring per litter were followed to 3 weeks, 5 months, or 10 months of age, at which time whole hearts were collected (n [≥] 5 per sex per exposure). Enhanced reduced representation bisulfite sequencing (ERRBS) was used to assess the cardiac DNA methylome at 3 weeks and 10 months, and RNA-seq was conducted at all 3 time points. MethylSig and edgeR were used to identify age-related differentially methylated regions (DMRs) and differentially expressed genes (DEGs), respectively, within each sex and exposure group. Cell type deconvolution of bulk RNA-seq data was conducted using the MuSiC algorithm and publicly available single cell RNA-seq data. ResultsThousands of DMRs and hundreds of DEGs were identified in control, DEHP, and Pb-exposed hearts across time between 3 weeks and 10 months of age. A closer look at the genes and pathways showing differential DNA methylation revealed that the majority were unique to each sex and exposure group. Overall, pathways governing development and differentiation were most frequently altered with age in all conditions. A small number of genes in each group showed significant changes in DNA methylation and gene expression with age, including several that were altered by both toxicants but were unchanged in control. We also observed subtle, but significant changes in the proportion of several cell types due to age, sex, and developmental exposure. DiscussionTogether these data show that perinatal Pb or DEHP exposures deflect normal age-related gene expression, DNA methylation programs, and cellular composition across the life course, long after cessation of exposure, and highlight potential biomarkers of developmental toxicant exposures. Further studies are needed to investigate how these epigenetic and transcriptional changes impact cardiovascular health across the life course.

genomics↗

bioRxiv2023

Effects of Developmental Lead and Phthalate Exposures on DNA Methylation in Adult Mouse Blood, Brain, and Liver Identifies Tissue- and Sex-Specific Changes with Implications for Genetic Imprinting

BackgroundMaternal exposure to environmental chemicals can cause adverse health effects in offspring. Mounting evidence supports that these effects are influenced, at least in part, by epigenetic modifications. ObjectiveWe examined tissue- and sex-specific changes in DNA methylation (DNAm) associated with human-relevant lead (Pb) and di(2-ethylhexyl) phthalate (DEHP) exposure during perinatal development in cerebral cortex, blood, and liver. MethodsFemale mice were exposed to human relevant doses of either Pb (32ppm) via drinking water or DEHP (5 mg/kg-day) via chow for two weeks prior to mating through offspring weaning. Whole genome bisulfite sequencing (WGBS) was utilized to examine DNAm changes in offspring cortex, blood, and liver at 5 months of age. Metilene and methylSig were used to identify differentially methylated regions (DMRs). Annotatr and Chipenrich were used for genomic annotations and geneset enrichment tests of DMRs, respectively. ResultsThe cortex contained the majority of DMRs associated with Pb (69%) and DEHP (58%) exposure. The cortex also contained the greatest degree of overlap in DMR signatures between sexes (n = 17 and 14 DMRs with Pb and DEHP exposure, respectively) and exposure types (n = 79 and 47 DMRs in males and females, respectively). In all tissues, detected DMRs were preferentially found at genomic regions associated with gene expression regulation (e.g., CpG islands and shores, 5 UTRs, promoters, and exons). An analysis of GO terms associated with DMR-containing genes identified imprinted genes to be impacted by both Pb and DEHP exposure. Of these, Gnas and Grb10 contained DMRs across tissues, sexes, and exposures. DMRs were enriched in the imprinting control regions (ICRs) of Gnas and Grb10, with 15 and 17 ICR-located DMRs across cortex, blood, and liver in each gene, respectively. The ICRs were also the location of DMRs replicated across target and surrogate tissues, suggesting epigenetic changes these regions may be potentially viable biomarkers. ConclusionsWe observed Pb- and DEHP-specific DNAm changes in cortex, blood, and liver, and the greatest degree of overlap in DMR signatures was seen between exposures followed by sex and tissue type. DNAm at imprinted control regions was altered by both Pb and DEHP, highlighting the susceptibility of genomic imprinting to these exposures during the perinatal window of development.

pharmacology and toxicology↗

bioRxiv2019

Perinatal exposure to lead results in altered DNA methylation in adult mouse liver and blood: Implications for target versus surrogate tissue use in environmental epigenetics

BackgroundDNA methylation is a critical epigenetic mechanism linking early developmental environment to long-term health. In humans, the extent to which toxicant-induced changes in DNA methylation in surrogate tissues, such as blood, mirror those in the target tissues is unclear. The Toxicant Exposures and Responses by Genomic and Epigenomic Regulators of Transcription (TaRGET II) consortium was established by the National Institute of Environmental Health Sciences to address the utility of surrogate tissues as proxies for toxicant-induced epigenetic changes in target tissues.\n\nObjectivesThe objective of this study was to investigate the effects of perinatal exposure to a human environmentally relevant level (32 ppm in maternal drinking water) of lead (Pb) on liver and blood DNA methylation in adult male and female mice. We hypothesized that developmental Pb exposure would lead to persistent changes in DNA methylation, and that a subset of differentially methylated loci would overlap between liver and blood.\n\nMethodsEnhanced reduced-representation bisulfite sequencing was used to assess DNA methylation in 5 month old Pb-exposed and control mice. Sex-stratified modeling of differential methylation by Pb exposure was conducted using an established bioinformatics pipeline.\n\nResultsAlthough Pb exposure ceased at 3 weeks of age, we observed thousands of stably modified, sex-specific differentially methylated regions in the blood and liver of Pb-exposed animals, including 44 genomically imprinted loci. In males, we discovered 5 sites that overlapped between blood and liver, and exhibited changes in DNA methylation in the same direction in both tissues.\n\nConclusionsThese data demonstrate that perinatal exposure to Pb induces sex-specific changes in hepatic DNA methylation in adulthood, some of which are also present in blood. Ongoing studies will provide additional exposure-specific insights, and include other epigenetic marks that will enable further refinement of the design and analysis of human studies where target tissues are inaccessible.

genomics↗