DNA methylation is an important epigenetic modification. DNA methyltransferases (Dnmts), which catalyze the formation of 5-methylcytosine, play a role in ovarian and embryonic development in some insects. However, the underlying mechanism of Dnmt in mediating ovarian and embryonic development remains unclear. In this study, the regulation and function of Bombyx mori Dnmt1 were investigated. By progressively deleting the sequence upstream of Dnmt1, a region located between −580 and −560 region from the transcription initiation site was found to have the most transcriptional activity. Electrophoretic mobility shift assay and chromatin immunoprecipitation demonstrated that transcription factor Y box binding protein (YBP), a homolog of human Y box binding protein 1 (YBX1), bound to the −580 to −560 region. YBP knockdown and overexpression in a Bombyx cell line indicated that YBP activates Dnmt1 expression. Furthermore, GST-pulldown and co-immunoprecipitation demonstrated that YBP and ovarian CCAAT/enhancer binding protein (C/EBPg) could bind each other. Simultaneous knockdown of C/EBPg and YBP was more effective than single-gene RNAi in inhibiting Dnmt1 expression and reducing the hatching rate. These results demonstrated that the interaction of C/EBPg and YBP activated Dnmt1 expression. Correlated with the expression profiles of the studies genes, our results suggest that high-level expression and interaction of C/EBPg and YBP in ovaries and embryos enhance the expression of Dnmt1, thus ensuring high reproduction rate in B. mori.

DNA甲基化是一种重要的表观遗传修饰。DNA 甲基转移酶 (Dnmts) 催化 5-甲基胞嘧啶的形成，在某些昆虫的卵巢和胚胎发育中发挥作用。然而，Dnmt 介导卵巢和胚胎发育的潜在机制仍不清楚。在这项研究中，对调节和功能家蚕家蚕DNMT1进行了调查。通过逐渐删除Dnmt1上游的序列，发现位于转录起始位点 -580 和 -560 区域之间的区域具有最大的转录活性。电泳迁移率变化测定和染色质免疫沉淀证明转录因子 Y 盒结合蛋白(YBP) 是人类 Y 盒结合蛋白 1 (YBX1) 的同源物，与 -580 至 -560 区域结合。Bombyx细胞系中的 YBP 敲低和过表达表明 YBP 激活Dnmt1表达。此外，GST 下拉和免疫共沉淀表明 YBP 和卵巢 CCAAT/增强子结合蛋白 (C/EBPg) 可以相互结合。同时敲低C/EBPg和YBP在抑制Dnmt1表达和降低孵化率方面比单基因 RNAi 更有效。这些结果表明 C/EBPg 和 YBP 的相互作用激活了Dnmt1表达。与研究基因的表达谱相关，我们的结果表明 C/EBPg 和 YBP 在卵巢和胚胎中的高水平表达和相互作用增强了Dnmt1的表达，从而确保了家蚕的高繁殖率。