PFHxS Exposure and the Risk of Non-Alcoholic Fatty Liver Disease

Single-cell RNA sequencing reveals tissue-specific transcriptomic changes induced by perfluorooctanesulfonic acid (PFOS) in larval zebrafish (Danio rerio)

Perfluorooctanesulfonic acid (PFOS) elicits adverse effects on numerous organs and developmental processes but the mechanisms underlying these effects are not well understood. Here, we use single-cell RNA-sequencing to assess tissue-specific transcriptomic changes in zebrafish (Danio rerio) larvae exposed to 16 µM PFOS or dimethylsulfoxide (0.01 %) from 3-72 h post fertilization (hpf). Data analysis was multi-pronged and included pseudo-bulk, untargeted clustering, informed pathway queries, and a cluster curated for hepatocyte biomarkers (fabp10a, and apoa2). Overall, 8.63 % (2390/27698) genes were significantly differentially expressed. Results from untargeted analysis revealed 22 distinct clusters that were manually annotated to specific tissues using a weight-of-evidence approach. The clusters with the highest number of significant differentially expressed genes (DEGs) were digestive organs, muscle, and otolith. Additionally, we assessed the distribution of pathway-specific genes known to be involved in PFOS toxicity: the PPAR pathway, β-oxidation of fatty acids, the Nfe2l2 pathway, and epigenetic modifications by DNA methylation, across clusters and identified the blood-related tissue to be the most sensitive. The curated hepatocyte cluster showed 220 significant DEGs and was enriched for the Notch signaling pathway. These findings provide insights into both established and novel sensitive target tissues and molecular mechanisms of developmental toxicity of PFOS.

PFHxA and PFHxS promote breast cancer progression in 3D culture: MEX3C-associated immune infiltration revealed by bioinformatics and machine learning

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants with widespread use and bioaccumulative potential. Short-chain PFAS such as perfluorohexanoic acid (PFHxA) and perfluorohexane sulfonate (PFHxS) have been introduced as safer alternatives to long-chain PFAS, yet their toxicological impacts remain poorly defined. In this study, we employed a 3D Gelatin methacryloyl (GelMA) hydrogel model to mimic the tumor microenvironment and investigated the effects of PFHxA and PFHxS on triple-negative breast cancer (TNBC) progression. At environmentally relevant concentrations (0.1-10 μM), both compounds significantly enhanced proliferation, migration, and invasion of MDA-MB-231 cells. Transcriptomic and machine learning analyses identified MEX3C as a key gene upregulated by PFAS exposure. Gene set enrichment analysis (GSEA) revealed activation of the PI3K-AKT-mTOR signaling pathway, which was further supported by siRNA-mediated knockdown of MEX3C, leading to a marked reduction in the expression levels of phosphorylated PI3K, AKT, and mTOR proteins. Furthermore, immune cell co-culture experiments showed that MDA-MB-231 cells with high MEX3C expression promoted M2 macrophage polarization, suppressed M1 polarization, and enhanced macrophage chemotactic activity, the immunomodulatory effects were significantly attenuated upon MEX3C knockdown. These findings establish MEX3C as a central mediator of PFAS-induced tumor progression and immune remodeling. This study provides mechanistic insight into the carcinogenic potential of emerging short-chain PFAS and underscores the need for stricter regulation to safeguard public health.

Gene targets with therapeutic potential in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths worldwide. Major treatments include liver transplantation, resection, and chemotherapy, but the 5-year recurrence rate remains high. Late diagnosis often prevents surgical intervention, contributing to poor patient survival rates. Carcinogenesis in HCC involves genetic alterations that drive the transformation of normal cells into malignant ones. Enhancer of zeste homolog 2 (EZH2), a key regulator of cell cycle progression, is frequently upregulated in HCC and is associated with advanced stages and poor prognosis, making it a potential biomarker. Additionally, signal transducer and activator of transcription 3, which binds to EZH2, affects disease staging and outcomes. Targeting EZH2 presents a promising therapeutic strategy. On the other hand, abnormal lipid metabolism is a hallmark of HCC and impacts prognosis. Fatty acid binding protein 5 is highly expressed in HCC tissues and correlates with key oncogenes, suggesting its potential as a biomarker. Other genes such as guanine monophosphate synthase, cell division cycle associated 5, and epidermal growth factor receptor provide insights into the molecular mechanisms of HCC, offering potential as biomarkers and therapeutic targets.

Predicting the molecular mechanisms of cardiovascular toxicity induced by per- and polyfluoroalkyl substances: an In Silico network toxicology perspective

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are human-made chemicals that accumulate in the human body and the environment over time. Humans are primarily exposed to PFAS through drinking water, food, consumer products, and dust. These exposures can have many adverse health effects, including cardiovascular diseases (CVDs) and factors contributing to CVDs. This study identified the molecular mechanisms of CVDs caused by PFAS.

METHODS

For this purpose, various computational tools, such as the Comparative Toxicogenomic Database, ShinyGO, ChEA3, MIENTURNET, GeneMANIA, STRING, and Cytoscape, were used to conduct in silico analyses.

RESULTS

The results showed that 10 genes were common between PFAS and CVDs, and among these common genes, the PPAR signaling pathway, fatty acid metabolic processes, and lipid binding were the most significantly associated gene ontology terms. Among the top 10 transcription factors (TFs) related to these common genes, peroxisome proliferator-activated receptor gamma and androgen receptor were the most prominent. Additionally, hsa-miR-130b-3p, hsa-miR-130a-3p, and hsa-miR-129-5p were featured microRNAs involved in PFAS-induced CVDs. Finally, PPARA and PPARG were identified as core genes involved in PFAS-induced CVDs.

CONCLUSION

These findings may contribute to a better understanding of the molecular mechanisms and reveal new potential targets in PFAS-induced CVDs.

Fgf8 contributes to the pathogenesis of Nager syndrome

Nager syndrome (NS, OMIM 154400) is a rare disease characterized by craniofacial and limb malformations due to variants in the gene encoding splicing factor 3B subunit 4 (SF3B4). Although various noncanonical functions of SF3B4 unrelated to splicing have been previously described, limited studies elucidate molecular mechanisms underlying NS pathogenesis. Here we showed that sf3b4-deficient fish displayed craniofacial and segmentation defects associated with suppression of fgf8 levels, which perturbed FGF signaling and neural crest cell (NCC) expression. Our finding also pointed out that oxidative stress-induced apoptosis was prominently detected in sf3b4-deficient fish and may further exaggerate the bone remodeling process. Notably, injection of exogenous FGF8 significantly rescued the demonstrated defects in sf3b4-deficient fish, which further supported the participation of Fgf8 in NS pathogenesis. Overall, our study provides valuable insights into the molecular mechanism underlying developmental abnormalities observed in NS and suggests future therapeutic strategies to protect against the pathogenesis of NS and possibilities for preventing severe outcomes.

Legacy and alternative per- and polyfluoroalkyl substances (PFAS) alter the lipid profile of HepaRG cells

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals used in various industrial and consumer products. They have gained attention due to their ubiquitous occurrence in the environment and potential for adverse effects on human health, often linked to immune suppression, hepatotoxicity, and altered cholesterol metabolism. This study aimed to explore the impact of ten individual PFAS, 3 H-perfluoro-3-[(3-methoxypropoxy) propanoic acid] (PMPP/Adona), ammonium perfluoro-(2-methyl-3-oxahexanoate) (HFPO-DA/GenX), perfluorobutanoic acid (PFBA), perfluorobutanesulfonic acid (PFBS), perfluorodecanoic acid (PFDA), perfluorohexanoic acid (PFHxA), perfluorohexanesulfonate (PFHxS), perfluorononanoic acid (PFNA), perfluorooctanoic acid (PFOA), and perfluorooctanesulfonic acid (PFOS) on the lipid metabolism in human hepatocyte-like cells (HepaRG). These cells were exposed to different concentrations of PFAS ranging from 10 µM to 5000 µM. Lipids were extracted and analyzed using liquid chromatography coupled with mass spectrometry (LC- MS-QTOF). PFOS at 10 µM and PFOA at 25 µM increased the levels of ceramide (Cer), diacylglycerol (DAG), N-acylethanolamine (NAE), phosphatidylcholine (PC), and triacylglycerol (TAG) lipids, while PMPP/Adona, HFPO-DA/GenX, PFBA, PFBS, PFHxA, and PFHxS decreased the levels of these lipids. Furthermore, PFOA and PFOS markedly reduced the levels of palmitic acid (FA 16.0). The present study shows distinct concentration-dependent effects of PFAS on various lipid species, shedding light on the implications of PFAS for essential cellular functions. Our study revealed that the investigated legacy PFAS (PFOS, PFOA, PFBA, PFDA, PFHxA, PFHxS, and PFNA) and alternative PFAS (PMPP/Adona, HFPO-DA/GenX and PFBS) can potentially disrupt lipid homeostasis and metabolism in hepatic cells. This research offers a comprehensive insight into the impacts of legacy and alternative PFAS on lipid composition in HepaRG cells.

p53 inhibitor or antioxidants reduce the severity of ethmoid plate deformities in zebrafish Type 3 Treacher Collins syndrome model

Treacher Collins syndrome-3 (TCS-3) is a rare congenital craniofacial disorder attributed to variants in the RNA pol I subunit C (POLR1C). The pathogenesis of TCS-3 linked to polr1c involves the activation of apoptosis-dependent p53 pathways within neural crest cells (NCCs). This occurs due to disruptions in ribosome biogenesis, and the restoration of polr1c expression in early embryogenesis effectively rescues the observed craniofacial phenotype in polr1c-deficient zebrafish. Clinical variability in TCS patients suggests interactions between genes and factors like oxidative stress. Elevated production of reactive oxygen species (ROS) in epithelial cells may worsen phenotypic outcomes in TCS individuals. Our study confirmed excessive ROS production in facial regions, inducing apoptosis and altering p53 pathways. Deregulated cell-cycle and epithelial-to-mesenchymal transition (EMT) genes were also detected in the TCS-3 model. Utilizing p53 inhibitor (Pifithrin-α; PFT-α) or antioxidants (Glutathione; GSH and N-Acetyl-L-cysteine; NAC) effectively corrected migrated NCC distribution in the pharyngeal arch (PA), suppressed oxidative stress, prevented cell death, and modulated EMT inducers. Crucially, inhibiting p53 activation or applying antioxidants within a specific time window, notably within 30 h post-fertilization (hpf), successfully reversed phenotypic effects induced by polr1c MO.

Transcriptomic analysis reveals mitochondrial dysfunction in the pathogenesis of Nager syndrome in sf3b4-depleted zebrafish

Nager syndrome (NS) is a rare acrofacial dysostosis caused by heterozygous loss-of-function variants in the splicing factor 3B subunit 4 (SF3B4). The main clinical features of patients with NS are characterized by facial-mandibular and preaxial limb malformations. The migration and specification of neural crest cells are crucial for craniofacial development, and mitochondrial fitness appears to play a role in such processes. Here, by analyzing our previously published transcriptome dataset, we aim to investigate the potential involvement of mitochondrial components in the pathogenesis of craniofacial malformations, especially in sf3b4 mutant zebrafish. We identified that oxidative phosphorylation (OXPHOS) defects and overproduction of reactive oxygen species (ROS) due to decreased antioxidants defense activity, which leads to oxidative damage and mitochondrial dysfunction. Furthermore, our results highlight that fish lacking sf3b4 gene, primarily display defects in mitochondrial complex I. Altogether, our findings suggest that mitochondrial dysfunction may contribute to the development of the craniofacial anomalies observed in sf3b4-depleted zebrafish.

Transcriptome alterations in sf3b4-depleted zebrafish: Insights into cataract formation in retinitis pigmentosa model

Posterior subcapsular cataract (PSC) frequently develops as a complication in patients with retinitis pigmentosa (RP). Despite numerous scientific investigations, the intricate pathomechanisms underlying cataract formation in individuals affected by RP remain elusive. Therefore, our study aims to elucidate the potential pathogenesis of cataracts in an RP model using splicing factor subunit 3b (sf3b4) mutant zebrafish. By analyzing our previously published transcriptome dataset, we identified that, in addition to RP, cataract was listed as the second condition in our transcriptomic analysis. Furthermore, we confirmed the presence of nucleus retention in the lens fiber cells, along with abnormal cytoskeleton expression in both the lens fiber cells and lens epithelial cells in sf3b4-depleted fish. Upon closer examination, we identified 20 differentially expressed genes (DEGs) that played a role in cataract formation, with 95 % of them related to the downregulation of structural lens proteins. Additionally, we also identified that among all the DEGs, 13 % were associated with fibrotic processes. It seems that the significant upregulation of inflammatory mediators, in conjunction with TGF-β signaling, plays a central role in the cellular biology of PSC and posterior capsular opacification (PCO) in sf3b4 mutant fish. In summary, our study provides valuable insights into cataract formation in the RP model of sf3b4 mutants, highlighting its complexity driven by changes in structural lens proteins and increased cytokines/growth factors.