DNA Methylation Dynamics in Development and Disease: Insights from Zebrafish Models

DNA methylation is a fundamental epigenetic modification that regulates gene expression, genome stability, and cell identity across vertebrate development. Disruption of DNA methylation homeostasis contributes to a wide spectrum of human diseases, including developmental disorders, neurological conditions, and cancer. Understanding how DNA methylation patterns are established, maintained, and dynamically remodeled during development is therefore essential for elucidating disease mechanisms and identifying therapeutic opportunities. The zebrafish (Danio rerio) has emerged as a powerful vertebrate model for investigating DNA methylation dynamics in vivo. Its external fertilization, optical transparency, rapid embryogenesis, and high fecundity enable direct observation and experimental manipulation of epigenetic processes at developmental stages that are difficult to access in mammalian systems. In addition, the core enzymatic machinery governing DNA methylation, including DNA methyltransferase (DNMT) and ten-eleven translocation (TET) protein families, is evolutionarily conserved between zebrafish and humans. In this review, we summarize current knowledge of the zebrafish methylome and the enzymatic regulators that control DNA methylation dynamics. We discuss how DNA methylation shapes early embryonic development, organogenesis, and cell fate decisions, and highlight insights gained from zebrafish models of human disease. Finally, we examine emerging technologies that are enabling increasingly precise interrogation of epigenetic regulation in vivo. Together, these advances position zebrafish as an important platform for bridging developmental epigenetics with human disease biology and therapeutic discovery.