Sparrow D B, Jen W C, Kotecha S, Towers N, Kintner C, Mohun T J
Division of Developmental Biology, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
Development. 1998 Jun;125(11):2041-51. doi: 10.1242/dev.125.11.2041.
The presomitic mesoderm of vertebrates undergoes a process of segmentation in which cell-cell interactions mediated by the Notch family of receptors and their associated ligands are involved. The vertebrate homologues of Drosophila &Dgr ; are expressed in a dynamic, segmental pattern within the presomitic mesoderm, and alterations in the function of these genes leads to a perturbed pattern of somite segmentation. In this study we have characterised Thylacine 1 which encodes a basic helix-loop-helix class transcription activator. Expression of Thylacine is restricted to the presomitic mesoderm, localising to the anterior half of several somitomeres in register with domains of X-Delta-2 expression. Ectopic expression of Thylacine in embryos causes segmentation defects similar to those seen in embryos in which Notch signalling is altered, and these embryos also show severe disruption in the expression patterns of the marker genes X-Delta-2 and X-ESR5 within the presomitic mesoderm. Finally, the expression of Thylacine is altered in embryos when Notch signalling is perturbed. These observations suggest strongly that Thylacine 1 has a role in the segmentation pathway of the Xenopus embryo, by interacting with the Notch signalling pathway.
脊椎动物的前体节中胚层经历一个分段过程，其中涉及由Notch家族受体及其相关配体介导的细胞间相互作用。果蝇&Dgr;的脊椎动物同源物在前体节中胚层内以动态的、分段的模式表达，这些基因功能的改变会导致体节分段模式受到干扰。在本研究中，我们鉴定了编码一种碱性螺旋-环-螺旋类转录激活因子的Thylacine 1。Thylacine的表达局限于前体节中胚层，定位于与X-Delta-2表达域对齐的几个体节球的前半部分。在胚胎中异位表达Thylacine会导致类似于Notch信号改变的胚胎中出现的分段缺陷，并且这些胚胎在前体节中胚层内的标记基因X-Delta-2和X-ESR5的表达模式也显示出严重破坏。最后，当Notch信号受到干扰时，胚胎中Thylacine的表达会发生改变。这些观察结果强烈表明，Thylacine 1通过与Notch信号通路相互作用，在非洲爪蟾胚胎的分段途径中发挥作用。
