Molecular mechanism of sensory placode differentiation from ES cells

与利用胚胎干细胞方法进行神经外胚层分化的研究进展相比，非神经外胚层分化的研究进展甚微。为了实现颅板和表皮等非神经外胚层的选择性分化，我们利用小鼠胚胎干细胞将非洲爪蟾研究获得的信息应用于SFEB培养（Matsuo-Takasaki et al., 2005; Watanabe et al., 2005）。我们发现BMP4和Dkk1是非洲爪蟾胚胎中诱导基因座分化的关键因子。这表明基因座分化的分子机制在进化过程中是保守的。我们还发现细胞外基质（ecm）之一的纤维连接蛋白支持有效的细胞粘附并诱导小鼠胚胎干细胞的表皮细胞分化。这些结果表明，BMP信号和与ecm的相互作用都是哺乳动物表皮发育所必需的。

Compared to the research progress made in the subject of neural ectoderm differentiation using the ES cell approach, progress made in non-neural ectoderm differentiation has been slight. To achieve selective differentiation of non-neural ectoderm such as cranial placode and epidermis, We have applied information gained from Xenopus research to SFEB culture (Matsuo-Takasaki et al., 2005 ; Watanabe et al., 2005) using mouse ES cells. We found that BMP4 and Dkk1 are critical factors to induce placode differentiation as reported in Xenopus embryo. This suggests that molecular mechanism of placode differentiation is conserved during evolution. We have also found that one of the extra cellular matrix (ECMs), fibronectin supports efficient cell adhesion and induces epidermal cell differentiation from mouse ES cells. These results suggested that BMP signaling and the interaction with ECMs are both necessary for the development of epidermis in mammalian systems.