Faculty of Industrial Science and Technology, Department of Biological Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan.
Biochem Biophys Res Commun. 2011 Apr 29;408(1):38-44. doi: 10.1016/j.bbrc.2011.03.113. Epub 2011 Mar 29.
Transcription factors play a crucial role in the development of various tissues. In particular, the transcription factors of the basic helix-loop-helix (bHLH) family are crucial regulators of neurodifferentiation. Previous studies suggested that the bHLH transcription factor Hand2 is essential for sympathetic nervous system neuron differentiation in vivo, but the molecular mechanisms involved have not been well elucidated. It is important for understanding their mode of action in cellular differentiation to clarify how these bHLH factors regulate distinct transcriptional targets in a temporally and spatially controlled manner. Recent reports on ES cell differentiation suggested that its molecular mechanism mimics that of in vivo neurogenesis. However, the diverse nature of ES cell populations has prevented efficient analysis. To address this issue, we previously established a cell line in P19 embryonal carcinoma (EC) cells. Efficient sympathetic nervous system (SNS) neuron differentiation is induced in the cell line. Using this cell line, we succeeded in showing that the interaction of bHLH transcription factor Hand2 with E2a is required for transcription of Phox2b, which is essential for autonomic nervous system neuron development, and this binding activates this expression in SNS differentiation. Moreover, we also demonstrated that Hes5 regulated the transcription of Phox2b as a negative regulator and it inhibited the SNS differentiation. These findings have enabled us to determine the novel regulatory mechanism of Phox2b in SNS differentiation.
转录因子在各种组织的发育中起着至关重要的作用。特别是，基本螺旋-环-螺旋(bHLH)家族的转录因子是神经分化的关键调节因子。先前的研究表明，bHLH 转录因子 Hand2 对于体内交感神经系统神经元的分化是必不可少的，但涉及的分子机制尚未得到很好的阐明。阐明这些 bHLH 因子如何以时间和空间控制的方式调节不同的转录靶标，对于理解它们在细胞分化中的作用模式非常重要。最近关于 ES 细胞分化的报告表明，其分子机制模拟了体内神经发生。然而，ES 细胞群体的多样性阻碍了有效的分析。为了解决这个问题，我们之前在 P19 胚胎癌细胞(EC)细胞中建立了一个细胞系。该细胞系中诱导出有效的交感神经系统(SNS)神经元分化。使用该细胞系，我们成功地表明，bHLH 转录因子 Hand2 与 E2a 的相互作用对于 Phox2b 的转录是必需的，Phox2b 对于自主神经系统神经元的发育是必需的，这种结合在 SNS 分化中激活了该表达。此外，我们还证明 Hes5 作为负调节剂调节 Phox2b 的转录，并抑制 SNS 分化。这些发现使我们能够确定 Phox2b 在 SNS 分化中的新的调节机制。
