Chan Techuan, Satow Reiko, Kitagawa Hirochika, Kato Shigeaki, Asashima Makoto
International Cooperative Research Project by JST (Japan Science and Technology Agency), Graduate School of Arts and Sciences, The University of Tokyo, Japan.
Zoolog Sci. 2006 Aug;23(8):689-97. doi: 10.2108/zsj.23.689.
Segmentation of the vertebrate body via the sequential formation of somites is an important process in embryogenesis. This sequential process is governed by the activation and regulation of Notch-related molecular oscillators by fibroblast growth factor and retinoic acid (RA) signaling. In this study, we identified ledgerline, a novel gene of Xenopus laevis expressed specifically in the presomitic mesoderm. Knockdown of ledgerline using antisense morpholino oligonucleotides shifted the developing somite front and altered the expression of genes that regulate molecular oscillation, including Delta2, ESR5, Hairy2a, and Thylacine1. Knockdown of ledgerline also downregulated RALDH-2 expression. Injection of RARalpha-CA, a constitutively active mutant of the RA receptor RARalpha, subsequently reduced the altered Thylacine1 expression. These results strongly suggest that ledgerline is essential for mesodermal RA activity and differentiation of the presomitic mesoderm during Xenopus somitogenesis.
通过体节的顺序形成对脊椎动物身体进行分割是胚胎发生过程中的一个重要过程。这个顺序过程受成纤维细胞生长因子和视黄酸（RA）信号对Notch相关分子振荡器的激活和调节所控制。在本研究中，我们鉴定出了ledgerline，这是非洲爪蟾的一个新基因，它在前体节中胚层中特异性表达。使用反义吗啉代寡核苷酸敲低ledgerline会使发育中的体节前缘发生移位，并改变调节分子振荡的基因的表达，包括Delta2、ESR5、Hairy2a和Thylacine1。敲低ledgerline还会下调RALDH-2的表达。随后注射RA受体RARalpha的组成型活性突变体RARalpha-CA，可降低Thylacine1表达的改变。这些结果强烈表明，ledgerline对于非洲爪蟾体节发生过程中中胚层RA活性和前体节中胚层的分化至关重要。
