High Temperature-Induced m⁶A Epigenetic Changes Affect Early Porcine Embryonic Developmental Competence in Pigs

N-6-methyladenosine (m(6)A), the most prevalent modification in eukaryotic messenger RNA (mRNA), plays a key role in various developmental processes in mammals. Three proteins that affect RNA m(6)A modification have been identified: methyltransferases, demethylases, and m(6)A-binding proteins, known as "writer," "eraser," and "reader" proteins, respectively. However, changes in the m(6)A modification when early porcine embryos are exposed to stress remain unclear. In this study, we exposed porcine oocytes to a high temperature (HT, 41 degrees C) for 10 h, after which the mature oocytes were parthenogenetically activated and cultured for 7 days to the blastocyst stage. HT significantly decreased the rates of the first polar body extrusion and blastocyst formation. Further detection of m(6)A modification found that HT can lead to increased expression levels of "reader," YTHDF2, and "writer," METTL3, and decreased expression levels of "eraser," FTO, resulting in an increased level of m(6)A modification in the embryos. Additionally, heat shock protein 70 (HSP70) is upregulated under HT conditions. Our study demonstrated that HT exposure alters m(6)A modification levels, which further affects early porcine embryonic development.