Genomic Imprinting at the Porcine DIRAS3 Locus.

Jinsoo Ahn,Kichoon Lee,Seongsoo Hwang,Mi-Ryung Park,In-Sul Hwang

doi:10.3390/ani11051315

Abstract

Simple SummaryDNA methylation associated with one of the two alleles from parents is an important mechanism that causes a silencing of that allele, leading to expression of another allele only. There has been a lack of detailed studies on DNA methylation and expression patterns that are related to the DIRAS3 gene in pigs. The objective of this study was to provide a comprehensive overview of DNA methylation and expression associated with the DIRAS3 gene in pigs by generating an embryonic pig model and analyzing next-generation sequencing using pig embryos and adult pigs. Our results clearly showed the presence of DNA methylation near the DIRAS3 gene in pigs and high expression of DIRAS3 in the hypothalamus from adult pigs and expression of only one allele in all the tested tissues including the hypothalamus. In summary, our findings suggested DNA methylation might be related to those unique gene expression patterns during the development of pigs. The epigenetic mechanisms underlying genomic imprinting include DNA methylation and monoallelic expression of genes in close proximity. Although genes imprinted in humans and mice have been widely characterized, there is a lack of detailed and comprehensive studies in livestock species including pigs. The purpose of this study was to investigate a detailed methylation status and parent-of-origin-specific gene expression within the genomic region containing an underexamined porcine DIRAS3 locus. Through whole-genome bisulfite sequencing (WGBS) and RNA sequencing (RNA-seq) of porcine parthenogenetic embryos and analyses of public RNA-seq data from adult pigs, DNA methylation and monoallelic expression pattern were investigated. As a result, maternal hypermethylation at the DIRAS3 locus and hypothalamus-specific and monoallelic expression of the DIRAS3 gene were found in pigs. In conclusion, the findings from this study suggest that the presence of maternal hypermethylation, or imprints, might be maintained and related to monoallelic expression of DIRAS3 during pig development.

Highlights

IntroductionThe epigenetic mechanisms underlying genomic imprinting include DNA methylation during mammalian embryonic development [2,3]
Genomic imprinting plays a crucial role in mammalian development and growth [1].The epigenetic mechanisms underlying genomic imprinting include DNA methylation during mammalian embryonic development [2,3]
Genes imprinted in humans and mice have been widely characterized, there is a lack of detailed and comprehensive studies in livestock species including pigs

Summary

Introduction

The epigenetic mechanisms underlying genomic imprinting include DNA methylation during mammalian embryonic development [2,3]. Our recent approach of the use of whole-genome bisulfite sequencing (WGBS) and RNA sequencing (RNA-seq) of porcine embryos that underwent parthenogenesis has facilitated verification of the imprinting status of known imprinted clusters and identification of novel imprinted genes [9,11]. This facilitation was attributed to a direct sequencing comparison between parthenogenetic and biparental porcine embryos. A detailed methylation status and parent-of-origin-specific gene expression within genomic regions containing underexamined target loci, such as the DIRAS3 locus, could be further investigated

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