JP
Labs and Faculty
Core Laboratories
Laboratory of Bioresource Regulation

AOKI Fugaku Prof. Ph.D.

Theme

Developmental biology, Reproduction

Keyword

Preimplantation development, Gene expression, Reprogramming

Message

The life begins by the fusion of an oocyte and spermatozoon to generate a zygote. The oocytes are terminally differentiated cells, whereas after fertilization, the zygotes are totipotent; they are possible to differentiate into all types of cells. It is mysterious and very interesting that such a remarkable transformation occurs during a short time period after fertilization. I have been studying for the mechanism by which this “mysterious” phenomenon occurs.

Note: In this year, Prof. Aoki will not accept graduate students.

Introduction

The oocytes are terminally differentiated cells; they express oocyte specific genes. After fertilization, the embryos are totipotent; they are possible to differentiate into all types of cells. This remarkable transformation entails reprogramming of the pattern of gene expression. This reprogramming may require the deletion of the program in maternal and paternal genome and then the establishment of a new program in the zygote genome. Although reprogramming of gene expression is thus important to establish the totipotent state in the zygote, the molecular mechanism underlying this event has not yet been well elucidated. We have found that H2A.Z and H3.3, a histone H2A and H3 variant, respectively, and dimethylation of H3K79 which function as active gene markers were removed from the genome of zygotes soon after fertilization. These results suggest that cell memory markers which propagate the gene expression pattern to the next generation after mitosis in the somatic cells are deleted to initialize the gene expression program in the zygotes after fertilization. Current studies are focused on the molecular mechanism by which those active gene markers are removed from chromatin just after fertilization and then the new program of gene expression starts.

  • a mouse zygote. Left panel: nucleosomes at M phase. Right panels: male and female pronuclei at the interphase (double staining for DNA (upper) and H3K9me2 (lower).

  • Microinjection of DNA into an oocyte.

Biography

2009-Present Professor, Laboratory of Bioresource Regulation, Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo.
1999-2009 Associate professor, Laboratory of Bioresource Regulation, Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo.
1996-1999 Assistant professor, Laboratory of Animal Genetics, Graduate School of Agricultural and Life Sciences, The University of Tokyo.