アクティブボード・２０１０年３月
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研究発表を行った学会；
・第３２回日本分子生物学会年会
　２００９年１２月９日〜１２日（横浜）

タイトル；Foxo1 is essential for in vitro vascular formation from embryonic stem cells.
　
発表者；朴　勝煥　[Seung-Hwan Park]　氏
　　　（熊本大学　発生医学研究所　組織幹細胞分野）

Abstract；
Background and Purpose: The forkhead transcription factors, Foxos participate in both embryonic and adult angiogenesis. The Foxo subgroups regulate the correct organization of the vascular system. One of them, Foxo1 is an important physiological regulator of endothelial morphology in response to VEGF. However, the molecular mechanisms involved in Foxo1-regulated vasculature development are largely unknown. In this study, to elucidate the cellular function of Foxo1, I used a three-dimensional culture system for the differentiation of Flk-1 expressing mesodermal precursor cells derived from ES cells to cord forming endothelial cells and associating vascular smooth muscle cells.
Methods: Foxo1 (+/+) or Foxo1 (-/-) ES cells were cultured with OP9 stromal cells for 4 days to induce differentiation of Flk1+ mesodermal cells. Flk1+ cells were purified by FACS and allowed to aggregate in suspension culture. Flk1+ cell aggregates were embedded in Type I collagen gel and cultured for 4 days in the presence of 50ng/mL VEGF-A. Dome-like gels were allowed to flatten by liquid adsorption and subjected to immunostaining.
Results: While Foxo1 (+/+) endothelial cells organized into long vessel-like structures associated with smooth muscle cells, Foxo1 (-/-) endothelial cells could form only short sprouts. Foxo1 (-/-) endothelial cells have punctate accumulation of filamentous actin, thick circumferential bundles of microtubules with small spikes at the tip of cells, and no interaction with smooth muscle cells. Our results suggest the involvement of Foxo1 in cytoskeletal remodeling of endothelial cells and recruitment of smooth muscle cells during vascular development.
Conclusions: The forkhead box transcription factor Foxo1 is essential for the formation of ES cell-derived vessel like structures consisting of extending endothelial tubes supported by smooth muscle cells.