Methyl-CpG–Binding Protein 2 Improves the Development of Mouse Somatic Cell Nuclear Transfer Embryos

Abstract

Methyl-CpG-binding domain proteins (MBPs) connect DNA methylation and histone modification, which are the key changes of somatic cell reprogramming. Methyl-CpG-binding protein 2 (MeCP2) was the first discovered MBP that has been extensively studied in the neurodevelopmental disorder Rett syndrome. However, a role for MeCP2 during cellular reprogramming associated with somatic cell nuclear transfer (SCNT) has not been examined. In this study, we discovered that MeCP2 expression was significantly lower in embryos generated by SCNT compared with those generated by intracytoplasmic sperm injection (ICSI). We genetically modified mouse embryonic fibroblasts (MEFs) to overexpress MeCP2 and serve as donor cells for nuclear transfer (NT) to investigate the effects of MeCP2 on preimplantation development of SCNT embryos. The blastocyst rate (35.71%) of MeCP2 overexpressed embryos (NT(+)) was significantly greater than in nontransgenic embryos (NT(-), 24.29%). Furthermore, immunofluorescence experiments revealed that 5-methylcytosine (5mC) was transferred to 5-hydroxymethylcytosine (5hmC) to a greater extent in NT(+) embryos than in NT(-) embryos. Real-time PCR evaluation of gene expression also showed that embryonic development-associated genes, such as Oct4 and Nanog, were significantly higher in the NT(+) group compared to the NT(-) group. Collectively, these results suggested that MeCP2 facilitated Tet3 activity, enhanced expression of pluripotency-related genes, and eventually improved the development of NT embryos. Finally, we performed chromatin immunoprecipitation to identify direct targets of MeCP2 and constructed a protein interaction network to elucidate several putative MeCP2 targets.

Genome-wide alteration in DNA hydroxymethylation in the sperm from bisphenol A-exposed men

“…Methyl-CpG-binding protein 2 (MeCP2) has been identified as the major 5hmC-binding protein in the brain [63]. Its expression also improves the development of mouse somatic cell nuclear transfer embryos, via a 5hmc-upregulating mechanism[64]. Interestingly, BPA exposure obviously upregulated expression of MeCP2, given abundance of MeCP2-expressing neurons significantly increased[65].…”

Role of microRNAs in embryo–endometrial interactions: biological functions and clinical applications

“…Another miRNA-regulated protein, Fbxw7, has been identified as a key molecule in cell cycle regulation [88] ; however, information about how it regulates human embryo development is limited. Furthermore, miR-302c directly targets methyl-DNA binding domain protein 2 (MBD2) [89] involved in the development of mouse embryos produced by somatic cell nuclear-transferred [90] . As epigenetic control is a vital component of the gene expression orchestra in the embryo, further studies could be pursued to determine how miRNAs regulate human embryo development via MBD2.…”

Strategies to Improve the Efficiency of Somatic Cell Nuclear Transfer

“…Methyl-CpG-binding domain proteins (MBPs) associate with DNA methylation and histone modification, which are the critical changes of somatic cell reprogramming. Methyl-CpG-binding protein 2 (Mecp2) expression was significantly low in cloned mouse embryos [183]. The overexpression of Mecp2 in mouse donor cells increased the blastocyst rate, expression levels of Oct4 and Nanog, and also the 5hmC level, while it decreased the 5mC level.…”

“…The overexpression of Mecp2 in mouse donor cells increased the blastocyst rate, expression levels of Oct4 and Nanog, and also the 5hmC level, while it decreased the 5mC level. Mecp2 may promote the activity of ten-eleven translocation 3 (Tet3), which mediates active DNA demethylation during mouse pre-implantation embryonic development [183]. Moreover, the overexpression of TET3 in the donor cells increased blastocyst formation rates and embryo quality in cloned goats [184] and cattle [163].…”