Global and Complement Gene-Specific DNA Methylation in Grass Carp after Grass Carp Reovirus (GCRV) Infection

Yaping Wang,Lv Xiong,Lanjie Liao,Rong Huang,Yongming Li,Lifei Luo,Zuoyan Zhu,Libo He

doi:10.3390/ijms19041110

Abstract

Grass carp reovirus (GCRV) causes huge economic loss to the grass carp cultivation industry but the mechanism remains largely unknown. In this study, we investigated the global and complement gene-specific DNA methylation in grass carp after GCRV infection aimed to uncover the mechanism underlying GCRV infection. The global DNA methylation level was increased after GCRV infection. Expression levels of enzymes involved in DNA methylation including DNA methyltransferase (DNMT), ten-eleven translocation proteins (TETs), and glycine N-methyltransferase (GNMT) were significantly altered after GCRV infection. In order to investigate the relationship between the gene expression level and DNA methylation level, two representative complement genes, complement component 3 (C3) and kininogen-1 (KNG1), were selected for further analysis. mRNA expression levels of the two genes were significantly increased at 5 and 7 days after GCRV infection, whereas the DNA methylation level at the 5′ flanking regions of the two genes were down-regulated at the same time-points. Moreover, a negative correlation was detected between gene expression levels and DNA methylation levels of the two genes. Therefore, the current data revealed a global and complement gene-specific DNA methylation profile after GCRV infection. Our study would provide new insights into understanding the mechanism underlying GCRV infection.

Highlights

Grass carp (Ctenopharyngodon idellus) is an important aquaculture species in China, accounting for about 18% of total freshwater aquaculture production
The global and complement gene-specific DNA methylation in grass carp after grass carp reovirus (GCRV) infection were investigated in order to uncover the mechanism underlying GCRV infection
Global DNA methylation measurement showed that the DNA methylation level in GCRV-infected group was significant higher than that of control group at 3, 5, 7, and 9 days post-infection, while no significant differences were observed in the first days post-infection

Summary

Introduction

Grass carp (Ctenopharyngodon idellus) is an important aquaculture species in China, accounting for about 18% of total freshwater aquaculture production. GCRV has been noticed with special concern by fish breeders and immunologists with the hope of developing disease-resistant breeding or understanding the mechanism of GCRV infection [3]. DNA methylation in the cytosine-phosphor-guanine (CpG) sites of promoter regions or CpG islands of genes may be associated with gene expression levels [5,6]. The DNA methylation of the cyp19a1a gene in rare minnow under bisphenol A exposure was negatively correlated with gene expression levels [10]. MRNA expression levels of the RIG-1 gene in grass carp after GCRV infection is negatively regulated by DNA methylation [11]. The CpA/CpG methylation of CiMDA5 of grass carp negatively regulates its mRNA expression and is tightly associated with resistance against GCRV [12]. Low salinity affects the expression level of the igf gene in the liver of half smooth tongue sole, whereas methylation level shows an opposite trend to that of gene expression levels [13]

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