Per- and Polyfluoroalkyl Substances Disrupt Mouse Embryo Compaction by Targeting c-MYC.

The impact of environmental contaminants on early mammalian development remains a significant concern for reproductive health and clinical embryology. Prior research has shown that epidemiological data correlate Per- and Polyfluoroalkyl Substances (PFAS) exposure with diminished quality in preimplantation embryos across various human populations. These synthetic fluorinated chemicals persist indefinitely in the environment and accumulate within biological tissues, potentially interfering with essential cellular transitions during the first week of gestation. The morula stage of development requires precise coordination of cell-to-cell adhesion and structural reorganization to ensure successful blastocyst formation. While these associations are well-documented in observational studies, the specific molecular pathways through which these persistent organic pollutants exert their toxic effects on early morphogenesis are not fully elucidated. This absence of evidence motivated the current investigation into the mechanistic basis of PFAS-induced developmental failure using a novel stem cell-based screening approach.

This research evaluates how specific Per- and Polyfluoroalkyl Substances (PFAS) influence the structural integrity and developmental potential of preimplantation mouse embryos. The investigators sought to identify which chemical variants within this broad class of industrial surfactants pose the greatest risk to early developmental milestones. A primary goal involved creating a high-throughput phenotypic screening platform using mouse Expanded Pluripotent Stem Cells (EPSCs) to model the compaction process. The team aimed to quantify the effects of these substances on the circularity and morphological quality of morula-like aggregates as a proxy for embryonic health. Researchers also intended to determine if the observed developmental defects stem from the disruption of specific transcriptional regulators like the c-MYC protein. Determining the Half-maximal Inhibitory Concentration (IC50) for protein complex interference provided a quantitative measure of chemical toxicity relative to established pharmacological inhibitors.

The study utilized a phenotypic screening platform based on the circularity of morula-like aggregates derived from mouse Expanded Pluripotent Stem Cells (EPSCs). Nineteen distinct Per- and Polyfluoroalkyl Substances (PFAS) were tested to observe their impact on cellular aggregation and the pivotal process of compaction. Perfluorooctanoic Acid (PFOA) was selected for in-depth analysis due to its significant inhibitory effects on cell polarity and adhesion molecule expression. Researchers measured the expression of adhesion molecules and assessed the proportion of high-quality aggregates at concentrations of 10 nM and 100 nM using advanced imaging techniques. Biochemical assays characterized the interference of the contaminant with the c-MYC/MAX complex formation to pinpoint the molecular target. The team employed the commercial inhibitor 10074-G5 as a comparative control to validate the observed transcriptional suppression in both stem cell models and mouse embryos. Rescue experiments involved the overexpression of the c-MYC protein to confirm its role in mitigating the damage induced by chemical exposure.

Perfluorooctanoic Acid (PFOA) emerged as the most potent disruptor among the five positive hits identified during the initial screening of nineteen different compounds. Exposure to 100 nM of this compound significantly inhibited the expression of adhesion molecules and compromised cell polarity in the morula-like aggregates. The proportion of high-quality aggregates decreased significantly even at a lower concentration of 10 nM, indicating high sensitivity to the toxin. Mechanistic analysis revealed that the chemical interfered with c-MYC/MAX complex formation with a Half-maximal Inhibitory Concentration (IC50) of 22.3 μM. Transcriptional activity of the regulator was suppressed at a lowest effective concentration of 40 μM, which is comparable to the efficacy of the known inhibitor 10074-G5. Similar developmental impairments were confirmed in mouse embryos, where the c-MYC inhibitor 10074-G5 also disrupted adhesion at 5 μM and polarization at 1000 nM. Overexpression of the target protein successfully rescued the damage, confirming that the disruption of this transcriptional pathway is the primary cause of the observed defects.

The findings demonstrate that Per- and Polyfluoroalkyl Substances (PFAS) directly impair the process of embryo compaction by targeting essential transcriptional machinery. This study identifies the c-MYC pathway as a vulnerable target for environmental toxins during the sensitive preimplantation stage of mammalian development. Such molecular interference likely explains the reduced embryo quality observed in human epidemiological studies and highlights the risks of environmental chemical exposure. The established screening platform using Expanded Pluripotent Stem Cells (EPSCs) offers a robust and scalable method for evaluating the reproductive toxicity of various industrial chemicals. Future research should explore whether other members of this chemical class share the same inhibitory mechanism or affect different stages of early morphogenesis. These insights provide a foundation for developing protective strategies and regulatory guidelines to mitigate environmental impacts on early mammalian development and fertility.