Review of research on insect DNA methylation

Author of the article:CHEN Wei1, 2, 3** XU Xue-Jiao1, 2, 3 CHEN Nan-Jing1, 2, 3 HE Wei-Yi1, 2, 3*** YOU Min-Sheng1, 2,

Author's Workplace：1. Institute of Applied Ecology and Research Centre for Biodiversity and Eco-Safety, Fujian Agriculture and Forestry University, Fuzhou 350002, China; 2. Fujian-Taiwan Joint Centre for Ecological Control of Crop Pests,Fujian Agriculture and Forestry University, Fuzhou 350002, China; 3. Key Laboratory of Integrated Pest Management of Fujian and Taiwan, China Ministry of Agriculture, Fuzhou 350002, China

Key Words：insect, DNA methylation, Dnmts, evolution, methodology

Abstract： DNA methylation is a branch of epigenetics that has been getting broad recognition and receiving extensive attention in recent years because of its important function in modulating gene expression and its association with many physiological and biochemical processes in living organisms. Their high species abundance, metamorphic development and complex phenotypes make the insects a useful group in which to explore the function of DNA methylation. DNA methylation in insects is mainly mediated by DNA methyltransferases (Dnmts), which vary greatly in different species. Most insects possess Dnmt1 but lack Dnmt3, which are responsible for maintenance and de novo DNA methylation, respectively. Dnmt2 (also termed TRDMT1) is ubiquitous among insects but its ability to bind DNA is weak. An overall low level, as well as spatio-temporal patterns of DNA methylation, are observed in insects. In insect genomes, DNA methylation is predominantly located in gene exons to functionally enhance gene expression, with higher methylation levels in evolutionarily conserved and extensively expressed genes, and lower levels in specifically expressed genes. The major methodologies currently used in the study of insect DNA methylation are summarized as bioinformatics-based prediction and experimentally-based techniques that include methylation specific restriction enzyme assays (MSRE), methylation sensitive amplified polymorphism (MSAP) and genomic sequencing. This paper summarizes methyltransferases in insects, the distribution and evolution of DNA methylation, as well as available methodologies used in current studies. It provides a synthesis of important updates and potential applications, and novel ideas and technologies for further research in this area.