Summary of Research Project Results under JSPS FY2002
"Research for the Future Program"

1.Research Institution Osaka University
2.Research Area Life Sciences
3.Research Field Regulation Networks of Eukaryotic Gene Expression
4.Term of Project FY 1998 - FY 2002
5.Project Number 98L01101
6.Title of Project Regulation of Gene Expression in Cell Differentiation

7.Project Leader
Name Institution,Department Title of Position
Toru, Nakano Osaka University, Research Institute for Microbial Diseases Professor

8.Core Members

Name Institution,Department Title of Position
Takashi, Fujita Tokyo Metropolitan Institute of Medical Science Chief
Masato, Nakafuku The University of Tokyo, Graduate School of Medicine Associate Professorv

9.Summary of Research Results

We analyzed gene regulation network in cell differentiation of three distinct cell lineages ; namely, hematopoietic, immune and neural cells.
  1. Hematopoietic System: Combining in vitro differentiation induction method from mouse embryonic stem cells to blood cells and Tet-off conditional gene expression system, we analyzed the function of various transcription factors in hematopoietic differentiation. GATA-2, a zinc finger type transcription factor essential for immature hematopoietic cells, turns out to enhance hematopoietic progenitor cells. This conclusion was opposite from the previous reports which used the fusion trasnscription factor of GATA-2 and ligand binding domain of estrogen receptor. From this and another results, we concluded that function of transcription factors are dependent on the context of cell differentiation.
  2. Immune System: Transcription factor IRF-3 is the critical regulator of innate immune responses. Normally IRF-3 is ubiquitously expressed in its dormant state, however upon infection of pathogens, it undergoes post translational activation. We analyzed the cascade of molecular events resulting in its activation. We also elucidated crystal structure of IRF-3. We established a new model for IRF-3 activation: specific phosphorylation of serine residues of IRF-3; IRF-3 homodimer formation via inter molecdular interaction between phosphorylated residues and the "pocket" structure; interaction of IRF-3 "acidic pocket" with coactivators p300/CBP . Our analysis further revealed that the "pocket" is also critical for interaction with hypothetical IRF-3 kinase.
  3. Neural System: We have demonstrated that the combinatorial expression and functions of a set of homeodomain-type (Pax6, Nkx2.2, Nkx6.1) and HLH-type (Olig1, Olig2, Ngn1, Ngn2, Ngn3, Mash1, Id1, Id2) play important roles in the patterned and ordered generation of multiple types of neurons and glia in the developing vertebrate central nervous system. Furthermore, we found that the same set of molecules regulates the proliferation and differentiation of neural stem cells in the adult brain and spinal cord. By applying such knowledge, we developed strategies to enhance latent regenerative potential of adult neural stem cells, and thereby could induce regeneration of new neurons in damaged tissues.

10.Key Words
(1)Cell Differentiation   (2)Transcription factors   (3)Hematopoietic cells
(4)Immune cells   (5)Neural cells   (6)Stem cells
(7)Interferon   (8)Neuron   (9)Glia