IMAMURA Takeshi The Cancer Institute of the Japanese Foundation for Cancer Research, Associate member, 癌研究所・生化学部, 主任研究員 (70264421)
KAWABATA Masahiro The Cancer Institite of the Japanese Foundation for Cancer Reserarch, Associate member, 癌研究所・生化学部, 主任研究員 (60224838)
KATO Mitsuyasu The Cancer Institute of the Japanese Foudnation for Cancer Research, Associate member, 癌研究所・生化学部, 主任研究員 (20194855)
|Budget Amount *help
¥14,900,000 (Direct Cost: ¥14,900,000)
Fiscal Year 2001: ¥4,200,000 (Direct Cost: ¥4,200,000)
Fiscal Year 2000: ¥4,900,000 (Direct Cost: ¥4,900,000)
Fiscal Year 1999: ¥5,800,000 (Direct Cost: ¥5,800,000)
1. We have studied the effects of Smads on osteoblast differentiation using adenovirus system. BMPs alone induced synthesis of alkaline phosphatase and differentiation of C2C12 cells, which were further enhanced in the presence of Smad1 or Smad5. Inhibitory Smads repressed the activity of BMPs. When the biological activities of BMP-4 and BMP-6 were studied, BMP-4 was found to bind to ALK-3, and activate Smad1, 5, and 8. In contrast, BMP-6 bound to ALK-2 and activated Smad1 and 5. Interestingly, combination of BMP-4 and BMP-6 induced strong induction of differentiation of C2C 12 cells compared to either BMP alone.
2. Endothelial cells express ALK-1 and ALK-5 for the receptors for TGF-beta, and they activate different sets of Smads. In order to elucidate target genes of ALK-1 and ALK-5, we have infected ALK-1 or ALK-5 adenoviruses into human umbilical vein endothelial cells, and tarried out oligonulceotide microarray analysis. Among 7000 human genes, we found that STAT1, endoglin, Id family transcription factors, Smad6, and Smad7 were induced by ALK-1. In contrast, claudin 5 is repressed by ALK-5, but not by ALK-1, suggesting that formation of tight junction is perturbed by ALK-5. Since ALK-5 induces growth inhibition while ALK-1 induces in vitro differentiation of endothelial cells, we concluded that the genes identified by the present study may be involved in the growth and differentiation of these cells.