2,4,6-Tribromophenol inhibits neural differentiation of mESCs by disrupting lipid metabolism and mitochondrial function.

2,4,6-Tribromophenol (TBP) is the most environmentally prevalent bromophenol pollutant. Although TBP tends to accumulate in the brain, its neurotoxic effects and underlying mechanisms remain poorly understood. In the present study, the neurodevelopmental toxicity of TBP was investigated using an in vitro neural differentiation model of mouse embryonic stem cells (mESCs). Results showed that during differentiation, TBP exposure suppressed the expression of the ectoderm marker Tfap2α on day 6. Moreover, after 12 days of exposure, TBP significantly reduced the protein expression levels of PAX6 (neural precursor marker) and TUBB3 (neuronal marker) and inhibited acetylcholinesterase (AChE) activity. TBP exhibited limited effects on canonical developmental signaling pathways, such as BMP, WNT, and Notch-Hes, suggesting that its inhibitory effect on neural differentiation may not depend on these pathways. Transcriptomic analysis revealed TBP-induced alterations in both lipid metabolism-related pathways and genes involved in the mitochondrial respiratory chain. Further biochemical validation experiments demonstrated that TBP upregulated the expression of the lipid uptake gene Cd36, leading to increased total cholesterol (TC) and triglyceride (TG) levels. Concurrently, mitochondrial oxidative stress was elevated, whereas mitochondrial membrane potential, complex I activity, and ATP content were markedly decreased. Therefore, TBP likely impaired neural differentiation by disrupting lipid homeostasis and mitochondrial function. This study enhances the understanding of the neurotoxic mechanisms of bromophenol pollutants and provides crucial scientific evidence for their health risk assessment.