DNA methylation and miRNA-1296 act in concert to mediate spatiotemporal expression of KPNA7 during bovine oocyte and early embryonic development

Abstract

BackgroundEpigenetic regulation of oocyte-specific maternal factors is essential for oocyte and early embryonic development. KPNA7 is an oocyte-specific maternal factor, which controls transportation of nuclear proteins important for early embryonic development. To elucidate the epigenetic mechanisms involved in the controlled expression of KPNA7, both DNA methylation associated transcriptional silencing and microRNA (miRNA)-mediated mRNA degradation of KPNA7 were examined.ResultsComparison of DNA methylation profiles at the proximal promoter of KPNA7 gene between oocyte and 6 different somatic tissues identified 3 oocyte-specific differentially methylated CpG sites. Expression of KPNA7 mRNA was reintroduced in bovine kidney-derived CCL2 cells after treatment with the methylation inhibitor, 5-aza-2′-deoxycytidine (5-Aza-CdR). Analysis of the promoter region of KPNA7 gene in CCL2 cells treated with 5-Aza-CdR showed a lighter methylation rate in all the CpG sites. Bioinformatic analysis predicted 4 miRNA-1296 binding sites in the coding region of KPNA7 mRNA. Ectopic co-expression of miRNA-1296 and KPNA7 in HEK293 cells led to reduced expression of KPNA7 protein. Quantitative real time PCR (RT-qPCR) analysis revealed that miRNA-1296 is expressed in oocytes and early stage embryos, and the expression reaches a peak level in 8-cell stage embryos, coincident with the time of embryonic genome activation and the start of declining of KPNA7 expression.ConclusionsThese results suggest that DNA methylation may account for oocyte-specific expression of KPNA7, and miRNA-1296 targeting the coding region of KPNA7 is a potential mechanism for KPNA7 transcript degradation during the maternal-to-zygotic transition.

Effects of KPNA7 gene polymorphisms on reproductive traits in France Large White pigs

“…SNPs in 5 ′ the regulatory region play an important role in regulation of gene expression. Epigenetic regulation regulates the expression of KPNA7 (Wang et al 2019). In this study, the mechanism of SNP regulating KPNA7 gene expression may be that SNP affects DNA methylation.…”

Effects of DNA Methylation on Gene Expression and Phenotypic Traits in Cattle: A Review

“…Three oocytespecific differentially methylated CpG sites were found by comparing DNA methylation profiles proximal to the KPNA7 gene promoter in oocytes and six different somatic cells. The results indicate that the restricted expression of the bovine KPNA7 gene in oocytes is regulated by DNA methylation of its proximal promoter and that demethylation of three CpG sites was closely associated with the tissue specificity of the KPNA7 gene [106]. Rekawiecki et al assessed the percentage of methylation in the promoters of progesterone receptor isozymes A (PGRA) and B (PGRB) and determined that the hypermethylation level of the promoter region of the PGRA subtype might be a mechanism for regulating the inhibition of PGRB activity by PGRA, which may affect the regulation of progesterone in the luteum and endometrium [107].…”

“…The KPNA7 gene, a maternal factor specific to oocytes, controls the transport of nuclear proteins and functions during early embryonic development [106]. Three oocytespecific differentially methylated CpG sites were found by comparing DNA methylation profiles proximal to the KPNA7 gene promoter in oocytes and six different somatic cells.…”

Epigenetic regulation of chemokine (CC‐motif) ligand 2 in inflammatory diseases

“…The loose/compressive state of chromatin is dynamic and is regulated by multiple mechanisms including DNA methylation, post‐translational modification (PTM) of histones (e.g., Lysine phosphorylation, acetylation, methylation, ubiquitination, lactation, etc. ), histone variants, ATP‐dependent chromatin remodelling and non‐coding RNA (ncRNA) 38–40 . Among them, histone post‐transcriptional modification, DNA methylation and ncRNA have been reported to be involved in the epigenetic regulation of CCL2 34,41,42 .…”

“…), histone variants, ATP‐dependent chromatin remodelling and non‐coding RNA (ncRNA). 38 , 39 , 40 Among them, histone post‐transcriptional modification, DNA methylation and ncRNA have been reported to be involved in the epigenetic regulation of CCL2. 34 , 41 , 42 Since most epigenetic modifications are proven to be reversible, epigenetic modification targeting CCL2 is expected to be a promising therapeutic strategy for inflammatory diseases.…”