DNA methylation-mediated expression of zinc finger protein 615 affects embryonic development in <i>Bombyx</i> <i>mori</i>
Guanfeng Xu, 华南师范大学生命科学学院昆虫科学与技术研究所, 广东省昆虫发育生物学与应用技术重点实验室, 广州市昆虫发育调控与应用研究重点实验室, 广东 广州510631, 中国, Chengcheng Gong, Yulin Tian, Tong‐Yu Fu, Yi-Guang Lin, Hao Lyu, Yuling Peng, Chunmei Tong, Qi-Li Feng, Qisheng Song, Si-Chun Zheng, 密苏里大学农业、食品与自然资源学院植物科学与技术系，密苏里州 哥伦比亚市65211, 美国
Abstract
Cell division and differentiation after egg fertilization are critical steps in the development of embryos from single cells to multicellular individuals and are regulated by DNA methylation via its effects on gene expression. However, the mechanisms by which DNA methylation regulates these processes in insects remain unclear. Here, we studied the impacts of DNA methylation on early embryonic development in <i>Bombyx</i> <i>mori</i>. Genome methylation and transcriptome analysis of early embryos showed that DNA methylation events mainly occurred in the 5' region of protein metabolism-related genes. The transcription factor gene <i>zinc</i> <i>finger</i> <i>protein</i> <i>615</i> (<i>ZnF615</i>) was methylated by DNA methyltransferase 1 (Dnmt1) to be up-regulated and bind to protein metabolism-related genes. <i>Dnmt1</i> RNA interference (RNAi) revealed that DNA methylation mainly regulated the expression of nonmethylated nutrient metabolism-related genes through <i>ZnF615</i>. The same sites in the <i>ZnF615</i> gene were methylated in ovaries and embryos. Knockout of <i>ZnF615</i> using CRISPR/Cas9 gene editing decreased the hatching rate and egg number to levels similar to that of <i>Dnmt1</i> knockout. Analysis of the <i>ZnF615</i> methylation rate revealed that the DNA methylation pattern in the parent ovary was maintained and doubled in the offspring embryo. Thus, Dnmt1-mediated intragenic DNA methylation of the transcription factor <i>ZnF615</i> enhances its expression to ensure ovarian and embryonic development.