Homeobox protein A1‐like and DNA methylation regulate embryo‐specific Zinc finger protein 615 gene expression and embryonic development in the silkworm Bombyx mori

Abstract

DNA methylation and transcription factors play roles in gene expression and animal development. In insects, DNA methylation modifies gene bodies, but how DNA methylation and transcription factors regulate gene expression is unclear. In this study, we investigated the mechanism that regulates the expression of Bombyx mori Zinc finger protein 615 (ZnF 615), which is a downstream gene of DNA methyltransferase 1 (Dnmt1), and its effects on the regulation of embryonic development. By progressively truncating the ZnF 615 promoter, it was found that the −223 and −190 nt region, which contains homeobox (Hox) protein cis-regulatory elements (CREs), had the greatest impact on the transcription of ZnF 615. RNA interference (RNAi)-mediated knockdown and overexpression of Hox family genes showed that Hox A1-like can enhance the messenger RNA level of ZnF 615. Further studies showed that Hox A1-like regulates ZnF 615 expression by directly binding to the −223 and −190 nt region of its promoter. Simultaneous RNAimediated knockdown or overexpression of Hox A1-like and Dnmt1 significantly inhibited or enhanced the regulatory effect of either gene alone on ZnF 615 expression, suggesting that both DNA methylation of gene bodies and binding of transcription factors to promoters are essential for gene expression. RNAi-mediated knockdown of Hox A1-like and Dnmt1 showed that the embryonic development was retarded and the hatching rate was decreased. Taken together, these data suggest that Hox A1-like and DNA methylation enhance the expression of ZnF 615, thereby affecting the development of B. mori embryos.

Methyl‐CpG binding domain (MBD)2/3 specifically recognizes and binds to the genomic mCpG site with a β‐sheet in the MBD to affect embryonic development in Bombyx mori

“…, 2020, 2022a, 2022b; Tian et al. , 2022) and embryos of N. vitripennis and B. germanica (Zwier et al. , 2012; Ventós‐Alfonso et al.…”

“…Although the methylation rates in insects are not as high as those in mammals, DNA methylation plays a role in insect development. By using a 5mC inhibitor, RNA interference (RNAi), or clustered regularly interspaced palindromic repeats (CRISPR) / CRISPR-associated protein 9 of DNA methyltransferase 1 (Dnmt1), DNA methylation was shown to affect the development of B. mori early embryos (blastoderm), ovaries, and wings (Xiang et al, 2013;Xu et al, 2020Xu et al, , 2022aXu et al, , 2022bTian et al, 2022) and embryos of N. vitripennis and B. germanica (Zwier et al, 2012;Ventós-Alfonso et al, 2020). Therefore, studying the interaction of MBD and mCpG will provide an understanding of how DNA methylation affects insect development through MBD2/3.…”