A Twist-like bHLH gene is a downstream factor of an endogenous FGF and determines mesenchymal fate in the ascidian embryos
A Twist-like bHLH gene is a downstream factor of an endogenous FGF and determines mesenchymal fate in the ascidian embryos
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DOI：
10.1242/dev.00652
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发表时间：
2003-09-01
期刊：
影响因子：
4.6
通讯作者：
Satou, Y
中科院分区：
文献类型：
--
作者：
Imai, KS;Satoh, N;Satou, Y
海鞘幼虫在其躯干中发育间充质细胞。成纤维细胞生长因子（FGF 9/16/20）对于在玻璃海鞘中诱导间充质是必需的并且是足够的。我们已经确定了两个基本的螺旋-环-螺旋（bHLH）基因命名为扭曲样1和扭曲样2作为下游因子的FGF。这两个基因在遗传学上密切相关，并且在110细胞期后的间充质细胞中特异性表达。使用特定的吗啉代寡核苷酸的基因敲除实验表明，Twist-like 1起着至关重要的作用，在确定间充质和Twist-like 2是Twist-like 1的下游因子。此外，Twist-like 1的过度表达和错误表达都将非间充质细胞转化为间充质细胞。4461我们还证明了Twist-like 1的上游调节机制在B系间充质细胞和A系间充质细胞之间是不同的，称为“躯干侧细胞”。FGF 9/16/20是Twist-like 1在B系间充质前体细胞中表达所需的，而FGF、FoxD和另一种称为NoTrlc的新型bHLH因子是Twist-like 1在A系间充质前体细胞中表达所需的。因此，Twist-like 1在间充质前体中的表达需要两种不同但部分重叠的机制，这触发了玻璃海鞘胚胎中间充质的分化。
Ascidian larvae develop mesenchyme cells in their trunk. A fibroblast growth factor (FGF9/16/20) is essential and sufficient for induction of the mesenchyme in Ciona savignyi. We have identified two basic helix-loop-helix (bHLH) genes named Twist-like1 and Twist-like2 as downstream factors of this FGF. These two genes are phylogenetically closely related to each other, and were expressed specifically in the mesenchymal cells after the 110-cell stage. Gene-knockdown experiments using a specific morpholino oligonucleotide demonstrated that Twist-like1 plays an essential role in determination of the mesenchyme and that Twist-like2 is a downstream factor of Twist-like1. In addition, both overexpression and misexpression of Twist-like1 converts non-mesenchymal cells to mesenchymal cells. 4461 We also demonstrate that the upstream regulatory mechanisms of Twist-like1 are different between B-line mesenchymal cells and the A-line mesenchymal cells called 'trunk lateral cells'. FGF9/16/20 is required for the expression of Twist-like1 in B-line mesenchymal precursor cells, whereas FGF, FoxD and another novel bHLH factor called NoTrlc are required for Twist-like1 to be expressed in the A-line mesenchymal precursor cells. Therefore, two different but partially overlapping mechanisms are required for the expression of Twist-like1 in the mesenchymal precursors, which triggers the differentiation of the mesenchyme in Ciona embryos.