Maternal high-fat diet alters Tet-mediated epigenetic regulation during heart development

Maternal exposure to balanced nutrition is critical for supporting embryonic development. Exposure to imbalanced nutrition during pregnancy, such as a high-fat diet (HFD), has been reported to negatively impact offspring, leading to conditions such as congenital heart disease. One possible mechanism is that metabolic stress from imbalanced food intake alters the function of epigenetic regulators, leading to abnormal transcriptional output in embryos. In this study, we observed that maternal exposure to a high-fat diet led to noncompaction cardiomyopathy (NCC) in embryos at E15.5. At the molecular level, maternal HFD exposure resulted in significantly reduced 5hmC production and chromatin remodeling in embryonic heart tissue collected from E15.5 embryos. Interestingly, maternal vitamin C treatment countered the negative impact of HFD exposure and restored the metabolic changes observed in pregnant mice, as well as the NCC phenotype observed in E15.5 embryos. This restoration is possibly due to the replenishment of iron, a co-factor of the Tet enzyme, in its reduced form. We further used a cardiac-specific Tet-triple knockout mouse model to confirm that the cardioprotective outcomes of maternal vitamin C treatment in HFD conditions are attributable to the enhanced activity of TET enzymes. Collectively, our results suggest a crosstalk between maternal nutrition exposure, such as HFD or vitamin C, and epigenetic rewriting during embryonic heart development。