Professor Takahiro Arima's group at the Graduate School of Medicine, Tohoku University, in collaboration with Professor Hiroyuki Sasaki's group at the Institute of Biodefense Medicine, Kyushu University, is in the process of differentiating human sperm and eggs into the placenta via fertilized eggs. We clarified how DNA methylation changes.
The placenta and foetation are derived from a single fertilized egg, and although they have the same genomic DNA information, they work completely differently.The mechanism that makes this possible is epigenetic modifications such as DNA methylation. It is known that abnormalities in DNA methylation lead to various human diseases such as miscarriage, abnormal growth of children, lifestyle-related diseases, and cancer.
Previous studies using experimental animals such as mice have shown that DNA methylation is almost completely reset in fertilized eggs.Therefore, this time, the joint research group of Professor Arima and Professor Sasaki investigated the DNA methylation status of all genes in human eggs, sperms, fertilized eggs and placental cells.
As a result, it was found that in humans, the reset of DNA methylation in fertilized eggs was incomplete, and some of the DNA methylation information in eggs was inherited by the placenta.That is, in the case of humans, this incomplete reset of DNA methylation regulates some genes by a mechanism different from that of mice.This clarified a part of the gene expression control mechanism specific to humans.
The results of this study are expected to be useful for elucidating all pathological conditions caused by abnormal DNA methylation in fertilized eggs and placenta and for developing treatment methods.It can also be a clue to understanding the inheritance of epigenetic information across generations.
