Summary of Research Project Results under JSPS FY2003
"Research for the Future Program"

1.Research Institution Tohoku University
2.Research Area Life Sciences
3.Research Field Angiogenesis and Vascular Development Control
4.Term of Project FY 1999 - FY 2003
5.Project Number 99L01304
6.Title of Project Isolation and Characterization of Genes Involved in Endothelial Cell Differentiation and Angiogenesis

7.Project Leader
Name Institution,Department Title of Position
Yasufumi, Sato Tohoku University, Institute of Development, Aging and Cancer Professor

8.Core Members

Names Institution,Department Title of Position
Minetarou, Ogawa Kumamoto University, Institute of Molecular Embryology and Genetics Professor
Mayumi ,Abe Tohoku University, Institute of Development, Aging and Cancer Assistant Professor

9.Summary of Research Results

   In this project, we have conducted studies on novel or uncharacterized molecules which are responsible for endothelial cell (EC) differentiation and angiogenesis.
   We have isolated two novel molecules that are involved in angiogenesis. One is puromycin insensitive leucyl-specific aminopeptidase (PILSAP), whose expression is augmented when mouse embryonic stem cells are differentiated to ECs. We found that PILSAP was induced in ECs by the stimulation of VEGF and played important role in the proliferation and migration of ECs. We characterized the mechanism of PILSAP regulation in EC proliferation and migration. The results indicate that PILSAP plays a crucial role in the intracellular signal transduction pathway of ECs via the binding and modification of signaling molecules such as phosphatidylinositol dependent kinase 1 (PDK1). The other is endothelium-derived angiogenesis inhibitor. We isolated this molecule via the analysis of VEGF-inducible genes in ECs and designated as "quot;vasohibin". Our analysis indicated that vasohibin was selectively expressed in ECs and inhibited angiogenesis as a negative feedback regulator of angiogenesis.
   We characterized the roles of transcription factors expressed in ECs such as Ets-1, HEX, PEBP-2, and VEZF-1 in angiogenesis. Our analysis indicates that they are classified as pro-angiogenic transcription factors and anti-angiogenic transcription factors, and angiogenesis is regulated by these two subsets of transcription factors.
   We have identified that endothelial cell differentiation is closely associated with hematopoietic cell differentiation. We found that hematogenic differentiation of embryonic endothelium appeared to serve as a major source of the definitive hematopoietic cell lineages. Commonality and specificity of hematogenic and angiogenic programs inherited in the endothelium are suggested to regulate commitment as well as further diversification of the definitive hematopoietic cell lineages. Studies by using an in vitro differentiation system of mouse embryonic stem cells and several in vivo models combined with antagonistic antibodies revealed novel functions of angiogenic growth factors on the cellular processes of vascular development. They included endothelial cell elongation regulated by VEGF-A/VEGFR-2 signals and a forkhead type transcription factor, integrity of endothelial sheet maintained by VEGF-C/VEGFR-3 signals and endothelial cell motility which is suppressed by Angiopoietin-1/Tie2 signals.
   We are confident that the findings identified in this project will provide valuable clues to understand the biological mechanisms underlying blood vessel formation.

10.Key Words
(1)endothelial cell  (2)aminopeptidase  (3)angiogenesis inhibitor 
(4)negative feedback  (5)transcription factor  (6)embryonic stem cell 
(7)blood cell  (8)VEGF  (9)angiopoietin