A team led by Professor Kazuo Yamagata (Faculty of Biology-Oriented Science and Technology, Kindai University) and Professor Tokuko Haraguchi (Graduate School of Frontier Biosciences, Osaka University) jointly conducted this research with Nao Yonezawa (1st year of the doctoral program at Graduate School of Biology-Oriented Science and Technology, Kindai University), Tomoko Shindo (Electron Microscope Laboratory, Keio University School of Medicine), Haruka Oda (Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, a postdoctoral fellow as of the time of this research), Professor Hiroshi Kimura (Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology), Professor Yasushi Hiraoka (Graduate School of Frontier Biosciences, Osaka University). This research group was the first in the world to succeed in constructing artificial cell nuclei by injecting purified DNA solution instead of sperm into living mouse eggs.
It had been possible to reconstruct the partial structure of an artificial cell nucleus inside a mouse oocyte; accurately reproducing its function was not successful. This research revealed the conditions necessary for the cell nucleus to function. The findings shed light on the mechanism, conditions and factors required for acquisition of nuclear functions, and are also expected to lead to new technologies such as the revival of extinct animals and the creation of artificial life.
The nucleus inside a cell is an important organelle involved in almost all biological phenomena, such as DNA replication and transcription. However, little progress has been made in studying on the process by which the structure and functions of a nucleus are established, or the factors required for formation of a nucleus.
The research group aimed to artificially create cell nuclei inside mammalian eggs in order to investigate the mechanism of nuclear construction and the minimum conditions necessary for nuclear formation.
The result suggested that by injecting purified DNA instead of sperm at appropriate timing, a fertilization-like process could be carried out and a structure very similar to a real nucleus could be constructed. The research group also found that the behavior of the injected DNA differed depending on the length and concentration of the DNA; they determined the optimal length and concentration of DNA.
By observing embryos injected with purified DNA, the research group verified that the injected DNA formed a nucleosome structure, that a nuclear membrane and nuclear pore complexes similar to those of a real nucleus had formed around the injected DNA, and that the transport function necessary for a nucleus was sufficient.
Furthermore, by using live cell imaging, the team became the first in the world to capture the injected DNA acquiring nuclear pore complexes.
This research succeeded in creating an artificial nucleus with nuclear transport functions. It is expected that further research will lead to the creation of a complete artificial cell nucleus, which could lead to the revival of extinct animals and the creation of artificial life.
