Publications

Background/Objectives: Citalopram is a selective serotonin reuptake inhibitor that is prescribed to relieve anxiety and depression. Widespread use has led to the contamination of freshwater systems downstream of wastewater treatment facilitates. Few studies have investigated the impact of citalopram on early embryonic development in humans or other species, despite the prevalence of intentional or unintentional exposure. Danio rerio (zebrafish) is a model organism for investigating effects of environmental exposure to xenobiotics on developmental outcomes in vertebrates.

Methods: In this study, we examined the metabolome of developing zebrafish embryos exposed to citalopram hydrobromide concentrations (0.03–250 ng/mL) spanning environmental to therapeutic doses during the first 24 h post-fertilization. Exposure was followed by 24 h exposure-free development before harvest at 48 h.

Results: Gross morphology of the embryos was normal, although changes were observed in the heart rates of citalopram-exposed embryos. Untargeted metabolomic and multivariate analyses revealed significant, nonlinear changes in the metabolome in response to citalopram exposure. Arginine and proline metabolism was significantly altered, potentially reflecting changes in serotonin signaling, nitric oxide metabolism, and polyamine synthesis.

Conclusions: Together, these data demonstrate that transient exposure to citalopram can induce long-lasting metabolomic changes during development, including dose-dependent changes that include aberrant metabolic processes in the developing metabolome. As a result, this work reveals potential biomarkers for early developmental exposure.

Lead (Pb) is a heavy metal associated with a range of toxic effects. Relatively few studies attempt to understand the impact of lead on development from a mechanistic perspective. Danio rerio (zebrafish) embryos are a model organism for studying the developmental consequences of exposure to chemical agents.

This study examined the metabolome of developing zebrafish embryos exposed to 5 ppb, 15 ppb, 150 ppb, and 1500 ppb Pb concentrations during the first 24 h post fertilization, followed by 24 h of unexposed development and harvest at 48 h. Untargeted metabolomics and multivariate analysis revealed that various Pb exposures differentially affected the embryonic metabolome.

Pathway analyses showed the dysregulation of biopterin, purine, alanine, and aspartate metabolism. Inductively coupled plasma mass spectrometry demonstrated Pb accumulation in embryos. Additionally, decreases in oxidation–reduction ratios were observed in 5–150 ppb groups but not in the 1500 ppb exposure group. This finding, along with several metabolite abundances, suggests a hormetic effect of Pb concentrations on the developing zebrafish metabolome.

Together, these data reveal persistent global changes in the embryonic metabolome, pin-point biomarkers for Pb exposure, unveil dose-dependent relationships, and reflect Pb-induced changes in cellular energy. This work highlights aberrant processes and persistent changes underlying low-dose heavy metal exposure during early development.

Much attention has been paid to the public health crisis that has resulted from the opioid epidemic. Given the high number of opioid users that are of childbearing age, the impact of utero exposure is a serious concern. Unfortunately, there is little knowledge regarding the consequences of opioid exposure during early development. While neurobehavioral effects of opioid exposure are well-documented, effects of exposure on embryogenesis remain largely unexplored.

To address this gap in knowledge, we investigated the effects of oxycodone and fentanyl exposure on gene expression in zebrafish (Danio rerio) embryos using whole embryo RNA sequencing. Embryos were exposed to environmentally relevant (oxycodone HCl 10.6 ng/L and fentanyl citrate 0.629 ng/L) and therapeutically relevant doses (oxycodone HCl 35.14 μg/L and fentanyl citrate 3.14 μg/L) from 2 to 24 h post-fertilization (hpf), followed by another 24 h of opioid-free development.

mRNA profiling at 48 hpf revealed dose- and drug-specific gene expression changes. Lower doses of oxycodone and fentanyl both induced more differentially expressed transcripts (DETs) than higher doses, potentially indicative of opioid receptor desensitization occurring at higher concentrations. In total, 892 DETs (corresponding to 866 genes) were identified across all conditions suggesting continued differential gene expression well after cessation of opioid exposure.

Gene ontology analysis revealed changes in gene expression relating to extracellular matrix (ECM) organization, cell adhesion, and visual and nervous system formation. Key pathways include those involved in axon guidance, synapse formation, and ECM biosynthesis/remodeling, all of which have potential implications on neural connectivity and sensory development.

These findings demonstrate that very early developmental exposure to opioids induces persistent transcriptomic changes which may have lasting implications for vertebrate cellular functions. Overall, these data provide insights into the molecular mechanisms of opioid-induced alterations during development.

Citalopram, a common selective serotonin reuptake inhibitor (SSRI), has been increasingly detected in aquatic environments due to ineffective removal and improper disposal. Although developmental exposure to SSRIs is linked to neurotoxicity, little is known about the persistence of gene expression alterations following limited exposure periods.

Zebrafish embryos were exposed from 2 to 24 h post-fertilization (hpf) at concentrations of citalopram hydrobromide spanning surface water to therapeutic serum levels (0.03, 0.9, 50, and 250 μg/L), followed by removal of the citalopram and development until 48 hpf. Whole-embryo RNA sequencing at 48 hpf revealed a non-linear dose–response wherein the lowest dose resulted in the induction of the highest number of differentially expressed genes (DEGs).

Gene set enrichment analyses (GSEA) and overrepresentation analyses (ORAs) showed that 0.03 μg/L citalopram caused upregulation of metabolic and developmental pathway genes, but suppressed synaptic membrane genes, whereas 0.9 μg/L resulted in strong downregulation of key neurotransmitter receptors. At 50 μg/L, genes linked to oxidative stress (glutathione metabolism and ferroptosis) were upregulated, and at 250 μg/L, stress and apoptotic processes were increased, while glutamate receptor genes were repressed.

All four citalopram doses suggested synaptic and neurotransmitter alterations, implying that persistent neurodevelopmental impacts resulted from a limited early window of exposure. These data highlight that transient, low-level SSRI exposures shape long-term embryonic gene expression.

Lamin A/C (LMNA) is an important component of nuclear lamina. Mutations cause arrhythmia, heart failure, and sudden cardiac death. While LMNA-associated cardiomyopathy typically has an aggressive course that responds poorly to conventional heart failure therapies, there is variability in severity and age of penetrance between and even within specific mutations, which is poorly understood at the cellular level.

Further, this heterogeneity has not previously been captured to mimic the heterozygous state, nor have the hundreds of clinical LMNA mutations been represented. Herein, we have overexpressed cardiopathic LMNA variants in HEK cells and utilized state-of-the-art quantitative proteomics to compare the global proteomic profiles of (1) aggregating Q353 K alone, (2) Q353 K coexpressed with WT, (3) aggregating N195 K coexpressed with WT, and (4) nonaggregating E317 K coexpressed with WT to help capture some of the heterogeneity between mutations.

We analyzed each data set to obtain the differentially expressed proteins (DEPs) and applied gene ontology (GO) and KEGG pathway analyses. We found a range of 162 to 324 DEPs from over 6000 total protein IDs with differences in GO terms, KEGG pathways, and DEPs important in cardiac function, further highlighting the complexity of cardiac laminopathies.

Pathways disrupted by LMNA mutations were validated with redox, autophagy, and apoptosis functional assays in both HEK 293 cells and in induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs) for LMNA N195 K. These proteomic profiles expand our repertoire for mutation-specific downstream cellular effects that may become useful as druggable targets for personalized medicine approach for cardiac laminopathies.

(Add abstract text here.)