Genome-Wide Analysis and Hormone Regulation of Chitin Deacetylases in Silkworm.

Ziyu Zhang,Qing Liu,Jing Gong,Yuhao Zhang,Jiamin Yan,Yong Hou

doi:10.3390/ijms20071679

Ziyu Zhang, Qing Liu + Show 4 more

Open Access

https://doi.org/10.3390/ijms20071679

Copy DOI

Abstract

Chitin deacetylases (CDAs) are a group of enzymes involved in chitin metabolism in insects; they play a critical role in molting, pupation, and the modification of chitin. In this study, we identified several CDAs in the silkworm, Bombyx mori (BmCDA), and investigated the effect of various hormones on their expression in B. mori larvae and embryo cell lines (BmE). Eight genes encoding BmCDAs were identified in the silkworm genome. They showed different expression patterns in different tissues, and were classified into three types based on where they were expressed: the exoskeleton, digestive organs, and genital organs. Moreover, we found that some BmCDAs showed upregulated expression during the molting period, especially during the fourth molting period in larvae. We also verified that the expression of BmCDA1–6 was upregulated by treatment with 20-hydroxyecdysone not only in larvae, but also in BmE cells. Interestingly, juvenile hormone analog treatment also upregulated the expression of some BmCDAs. The overexpression of several transcription factors revealed that the POU transcription factor POUM2 may play a major role in the regulation of BmCDA expression. Finally, the silencing of BmCDA1 and BmCDA2 did not lead to abnormal phenotypes or death, but may have led to delays in silkworm pupation. These results provide important information about lepidopteran insects in terms of chitin deacetylases and the regulation of their expression.

Highlights

Chitin is a polysaccharide that is formed by the polymerization of N-acetylglucosamine
To better understand the phylogenetic relationships of chitin deacetylases in silkworms compared to those in other species, we identified all the Chitin deacetylases (CDAs) expressed in silkworms and carried out a comparative and phylogenetic analysis of CDAs originating from fungi, bacteria, marine bacteria, and arthropods
The expression levels of BmCDA1–BmCDA6, which were upregulated by 20E treatment (Figure 5A–F), were upregulated by the overexpressing of POUM2 in B. Mori Embryo (BmE) cells (Figure 7D). These results show that the three transcription factors investigated, especially POUM2, potentially played a key role in regulating the expression of B. mori chitin deacetylases (BmCDAs) mediated by 20E

Summary

Introduction

Chitin is a polysaccharide that is formed by the polymerization of N-acetylglucosamine. It is widely found in the shells of crustaceans, skin of insects, and cytoderm of fungi [1], as well as in many green algae [2]. Growth and development is majorly associated with the biosynthesis and modification of chitin [4]. The initial substrate in the insect chitin biosynthesis pathway is trehalose—this pathway leads to the synthesis of chitin precursors by chitin synthase [5]. Chitin precursors are partially deacetylated to form chitin, and the deacetylation of chitin is necessary for the structure, permeability, and mechanical properties of the cuticle that makes it more soft and soluble in most insects [6,7,8,9,10]

Methods

Results

Conclusion