Integrative methylome and transcriptome analysis of Japanese flounder (Paralichthys olivaceus) skeletal muscle during development

Abstract

AbstractDNA methylation is an important epigenetic modification in vertebrate and is essential for epigenetic gene regulation in skeletal muscle development. We showed the genome-wide DNA methylation profile in skeletal muscle tissue of larval 7dph (JP1), juvenile 90dph (JP2), adult female 24 months (JP3) and adult male 24 months (JP4) Japanese flounder. The distribution and levels of methylated DNA within genomic features (1stexons, gene body, introns, TSS200, TSS1500 and intergenic) show different developmental landscapes. We also successfully identified differentially methylated regions (DMRs) and different methylated genes (DMGs) through a comparative analysis, indicating that DMR in gene body, intron and intergenic regions were more compared to other regions of all DNA elements. A gene ontology analysis indicated that the DMGs were mainly related to regulation of skeletal muscle fiber development process, Axon guidance, Adherens junction, and some ATPase activity. Methylome and transcriptome clearly revealed a exhibit a negative correlation. And integration analysis revealed a total of 425, 398 and 429 negatively correlated genes with methylation in the JP2_VS_JP1, JP3_VS_JP1 and JP4_VS_JP1 comparison groups, respectively. And these genes were functionally associated with pathways including Adherens junction, Axon guidance, Focal adhesion, cell junctions, Actin cytoskeleton and Wnt signaling pathways. In addition, we validated the MethylRAD results by bisulfite sequencing PCR (BSP) in some of the differentially methylated skeletal muscle growth-related genes (Myod1, Six1 and Ctnnb1). In this study, we have generated the genome-wide profile of methylome and transcriptome in Japanese flounder for the first time, and our results bring new insights into the epigenetic regulation of developmental processes in Japanese flounder. This study contributes to the knowledge on epigenetics in vertebrates.Author summaryEpigenetic mechanisms like DNA methylation have recently reported as vital regulators of some species skeletal muscle development through the control of genes related to growth. To date, although genome-wide DNA methylation profiles of many organisms have been reported and the Japanese flounder reference genome and whole transcriptome data are publically available, the methylation pattern of Japanese flounder skeletal muscle tissue remains minimally studied and the global DNA methylation data are yet to be known. Here we investigated the genome-wide DNA methylation patterns in Japanese flounder, throughout its development. These findings help to enrich research in molecular and developmental biology in vertebrates.