| Co-Investigator(Kenkyū-buntansha) |
KATO Mitsuyasu University of Tsukuba, Graduate School of Comprehensive Human Sciences, Professor, 大学院人間総合科学研究科, 教授 (20194855)
SUZUKI Hiroyuki University of Tsukuba, Graduate School of Comprehensive Human Sciences, Research Associate, 大学院人間総合科学研究科, 助手 (70375509)
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| Budget Amount *help |
¥14,500,000 (Direct Cost: ¥14,500,000)
Fiscal Year 2006: ¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2005: ¥11,100,000 (Direct Cost: ¥11,100,000)
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| Research Abstract |
We have already shown that Id1 and Herp2 promote and block angiogenic responses in endothelial cells, respectively. In present study, we tried to isolate Id1-and Herp2-interacting molecules which modulate function of Id1 and Herp2 by yeast two hybrid method. Among molecules isolated, E2-2, Id2, CGI-128, FHL2 and FLJ13861 could interact with either Id1 or Herp2 in mammalian cells. Out of them, we focused on E2-2 in further experiments because the heterodimer complex formation between E2-2 and Id1 was the strongest. Indeed, Id1 efficiently inhibited E2-2-induced luciferase activity. When E2-2 was over-expressed in endothelial cells, serum-induced proliferation and network formation in endothelial cells was suppressed in contrast with expression of Id1 in endothelial cells. To elucidate the mechanism by which E2-2 blocks angiogenic responses in endothelial cells, we tested the expression of VEGFR2, of which expression is known to be induced during endothelial activation, in endothelial ce
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lls when E2-2 was expressed in cells. As expected, expression of VEGFR2 mRNA was inhibited by E2-2, whereas E2-2-mediated decrease of VEGFR2 expression was improved by introduction of Id1 in the cells. Consistent with reduction of VEGFR2 mRNA, VEGFR2-lucifease activity was blocked by E2-2. Thus, it is possible that Id1 potentiates angiogenic responses in endothelial cells due to making heterodimer with E2-2 which substantially suppresses endothelial cell activation by blocking of VEGFR2 transcript.
We also made ALK5 knock-in mice which can not transduce TGF-β/ALK5 signaling, but still possess TGF-β/ALK1 signaling. ALK5 knock-in mice die at E10.5 like ALK5 knock-out mice. We could not observe any mature vessel formation in yolk sac in ALK5 knock-in mice. The phenotype of yolk sac from ALK5 knock-in mice was quite similar to that from ALK5 knock-out mice. However, labyrinth formation in placenta from ALK5 knock-in mice could be detected in contrast with ALK5 knock-out mice. Thus, TGF-β/ALK1 signaling might improve defect of labyrinth formation seen in ALK5 knock-out mice. Less
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