Oocyte IVM or vitrification significantly impairs DNA methylation patterns in blastocysts as analysed by single-cell whole-genome methylation sequencing

• Published in: Reproduction fertility and development Vol. 32; no. 7; p. 676
• Main Authors: Zhao, Ya-Han, Wang, Jing-Jing, Zhang, Pei-Pei, Hao, Hai-Sheng, Pang, Yun-Wei, Wang, Hao-Yu, Du, Wei-Hua, Zhao, Shan-Jiang, Ruan, Wei-Min, Zou, Hui-Ying, Hao, Tong, Zhu, Hua-Bin, Zhao, Xue-Ming
• Format: Journal Article
• Language: English
• Published: Australia 01.01.2020
• Subjects: Animals; Blastocyst - metabolism; Cattle - embryology; Cryopreservation - veterinary; DNA Methylation - genetics; DNA Methylation - physiology; Female; Fertilization in Vitro - veterinary; In Vitro Oocyte Maturation Techniques; Single-Cell Analysis - methods; Single-Cell Analysis - veterinary; Whole Genome Sequencing - methods; Whole Genome Sequencing - veterinary
• ISSN: 1031-3613
• DOI: 10.1071/RD19234

To explore the mechanisms leading to the poor quality of IVF blastocysts, the single-cell whole-genome methylation sequencing technique was used in this study to analyse the methylation patterns of bovine blastocysts derived from invivo, fresh (IVF) or vitrified (V_IVF) oocytes. Genome methylation levels of blastocysts in the IVF and V_IVF groups were significantly lower than those of the invivo group (P<0.05). In all, 1149 differentially methylated regions (DMRs) were identified between the IVF and invivo groups, 1578 DMRs were identified between the V_IVF and invivo groups and 151 DMRs were identified between the V_IVF and IVF groups. For imprinted genes, methylation levels of insulin-like growth factor 2 receptor (IGF2R) and protein phosphatase 1 regulatory subunit 9A (PPP1R9A) were lower in the IVF and V_IVF groups than in the invivo group, and the methylation level of paternally expressed 3 (PEG3) was lower in the V_IVF group than in the IVF and invivo groups. Genes with DMRs between the IVF and invivo and the V_IVF and IVF groups were primarily enriched in oocyte maturation pathways, whereas DMRs between the V_IVF and invivo groups were enriched in fertilisation and vitrification-vulnerable pathways. The results of this study indicate that differences in the methylation of critical DMRs may contribute to the differences in quality between invitro- and invivo-derived embryos.