Cycloleucine negatively regulates porcine oocyte maturation and embryo development by modulating N6-methyladenosine and histone modifications

Maturation of oocytes and early embryo development are regulated precisely by numerous factors at transcriptional and posttranslational levels through precise mechanisms. N6-methyladenosine (m(6)A) is the most common modification in mRNA which regulates RNA metabolism and gene expression. However, the role of RNA m(6)A on porcine oocyte maturation and early embryogenesis is largely unknown. Here, we found that oocytes treated with cycloleucine (CL), an RNA m(6)A inhibitor, express impaired cumulus expansion, increased production of reactive oxygen species (ROS) in the mitochondria, and delayed maturation of oocytes by disrupting spindle organization and chromosome alignment. Also, CL halted the development of embryos at the 4-cell stage and resulted in low-quality blastocysts. Furthermore, CL treatment decreased the RNA m(6)A, H3K4me3, and H3K9me3 levels, but increased the acetylation level of H4K16 during parthenogenetic embryonic development in pigs. Single-cell RNA-seq (scRNA-seq) analysis further revealed that CL treatment dramatically up-regulated the expression of metabolism-related genes (SLC16A1, and MAIG3 etc.) and maternal related genes, including BTG4, WEE2, and BMP15 among others, at the blastocyst stage. Taken together, inhibition of RNA m(6)A by CL impaired meiosis of oocytes and early embryonic development of porcine via RNAm(6)A methylation, histone modifications, and altering the expression of metabolism-related genes in blastocysts. (C) 2021 Published by Elsevier Inc.

Automated summary

Inhibition of RNA m(6)A with cycloleucine (CL) impairs porcine oocyte maturation and early embryonic development, resulting in compromised cumulus expansion, increased ROS production in mitochondria, and halted embryo development. Additionally, CL treatment affects the expression of metabolism-related genes and histone modifications in blastocysts.