Genome-wide, Single-Cell DNA Methylomics Reveals Increased Non-CpG Methylation during Human Oocyte Maturation

• Main Authors: Bo Yu, Xiao Dong, Silvia Gravina, Önder Kartal, Timothy Schimmel, Jacques Cohen, Drew Tortoriello, Raifa Zody, R. David Hawkins, Jan Vijg
• Format: Article
• Language: English
• Published: Elsevier 2017-07-01
• Series: Stem Cell Reports
• Subjects: single cell; DNA methylome; human oocyte; oocyte maturation; non-CpG methylation; epigenome; in vitro maturation
• Online Access: http://www.sciencedirect.com/science/article/pii/S2213671117302333

The establishment of DNA methylation patterns in oocytes is a highly dynamic process marking gene-regulatory events during fertilization, embryonic development, and adulthood. However, after epigenetic reprogramming in primordial germ cells, how and when DNA methylation is re-established in developing human oocytes remains to be characterized. Here, using single-cell whole-genome bisulfite sequencing, we describe DNA methylation patterns in three different maturation stages of human oocytes. We found that while broad-scale patterns of CpG methylation have been largely established by the immature germinal vesicle stage, localized changes continue into later development. Non-CpG methylation, on the other hand, undergoes a large-scale, generalized remodeling through the final stage of maturation, with the net overall result being the accumulation of methylation as oocytes mature. The role of the genome-wide, non-CpG methylation remodeling in the final stage of oocyte maturation deserves further investigation.