Dynamic reprogramming and function of RNA N⁶-methyladenosine modification during porcine early embryonic development

Abstract

Summary N6-Methyladenosine (m6A) regulates oocyte-to-embryo transition and the reprogramming of somatic cells into induced pluripotent stem cells. However, the role of m6A methylation in porcine early embryonic development and its reprogramming characteristics in somatic cell nuclear transfer (SCNT) embryos are yet to be known. Here, we showed that m6A methylation was essential for normal early embryonic development and its aberrant reprogramming in SCNT embryos. We identified a persistent occurrence of m6A methylation in embryos between 1-cell to blastocyst stages and m6A levels abruptly increased during the morula-to-blastocyst transition. Cycloleucine (methylation inhibitor, 20 mM) treatment efficiently reduced m6A levels, significantly decreased the rates of 4-cell embryos and blastocysts, and disrupted normal lineage allocation. Moreover, cycloleucine treatment also led to higher levels in both apoptosis and autophagy in blastocysts. Furthermore, m6A levels in SCNT embryos at the 4-cell and 8-cell stages were significantly lower than that in parthenogenetic activation (PA) embryos, suggesting an abnormal reprogramming of m6A methylation in SCNT embryos. Correspondingly, expression levels of m6A writers (METTL3 and METTL14) and eraser (FTO) were apparently higher in SCNT 8-cell embryos compared with their PA counterparts. Taken together, these results indicated that aberrant nuclear transfer-mediated reprogramming of m6A methylation was involved in regulating porcine early embryonic development.

Effects of Exogenous Glycine Betaine and Cycloleucine on Photosynthetic Capacity, Amino Acid Composition, and Hormone Metabolism in Solanum melongena L

“…However, this has not been reported for plants [11][12][13] . GB (N, N, N-trimethylglycine) is a secondary metabolite widely found in plants and animals and is an important osmoregulatory substance 2 .…”

Genetic Regulation of N6-Methyladenosine-RNA in Mammalian Gametogenesis and Embryonic Development

“…In pigs, it was found that m 6 A methylation continued from zygote stage to blastocyst stage, and the methylation level suddenly increased significantly in the transition period from morula to blastocyst. The in vitro application of cycloleucine (methylation inhibitor) effectively reduced the m 6 A modification level, significantly reduced the ratio of 4-cell embryos to blastocysts, and disturbed the normal embryonic cell differentiation ( Yu et al, 2021 ). Interestingly, studies have shown that METTL3 mediated m 6 A methylation negatively regulates autophagy to support porcine blastocyst development ( Cao et al, 2021 ).…”

RNA m6A modifications in mammalian gametogenesis and pregnancy

“…Cycloleucine is a methylation inhibitor, and cycloleucine treatment effectively reduced m6A levels, significantly reduced the ratio of four-cell embryos to blastocysts, disrupted normal lineage allocation, and increased apoptosis and autophagy levels in pig blastocysts (Yu et al 2021). Further, RNA m6A methylation appeared to be critical for early embryonic development, and abnormal nuclear transfer-mediated m6A methylation reprogramming is involved in the regulation of early embryonic development in pigs.…”