Gene expression patterns and DNA methylation of neuron and pancreatic β-cell developments in zebrafish embryos...

Bisphenol F (BPF) and bisphenol AF (BPAF) are structural analogues of bisphenol A (BPA) that are used in the manufacture of a myriad of BPA-free products; however, there is a paucity of information regarding their developmental effects. The present study investigates the effects of BPF and BPAF on neurodevelopment and pancreatic β-cell differentiation via altering DNA methylation and gene expression patterns using the zebrafish model. BPF and BPAF induced behavioral perturbations: increased average speed, increased maximum acceleration, increased mania time and decreased static time, in 0.3 and 1.0 μM groups in zebrafish embryos. Glucose level was significantly increased in 1.0 μM BPF (28 %); while a monotonic increase of 29 %, 55 %, and 74 % were observed in 0.1, 0.3, and 1.0 μM BPAF, respectively. Consistent with a decreased insulin mRNA level, the expression of two critical transcription factors (pdx-1 and foxa2) essential for the development and functioning of beta-cells decreased following the bisphenols exposure. In addition, embryonic exposure to BPF and BPAF upregulated the transcription of developmental genes (vegfa, wnt8a, and mstn1) and neuron-related genes (mbp, elavl3, gap43, gfap). Also, the expressions of DNA methyltransferases (dnmt1, dnmt3, dnmt4, dnmt5, dnmt6, dnmt7, and dnmt8) were significantly aberrant compared with the control group. The Bisulfite PCR results indicate increased DNA methylation at promoter regions of pdx-1 in BPF (8.2 %) and BPAF (7.6 %); α1-tubulin in BPF (5.3 %) and in BPAF (4.1 %), congruous with the increased dnmt1 and dnmt3 transcription, at early stage of zebrafish development. The present study indicates that zebrafish embryonic exposure to BPF and BPAF elicits islet dysfunction and neuron perturbations resulting in increased DNA methylation levels.