Gli function is essential for motor neuron induction in zebrafish.
Gli function is essential for motor neuron induction in zebrafish.
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DOI：
10.1016/j.ydbio.2005.04.010
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发表时间：
2005-06
影响因子：
2.7
通讯作者：
G. Vanderlaan;O. Tyurina;R. Karlstrom;A. Chandrasekhar
中科院分区：
文献类型：
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作者：
G. Vanderlaan;O. Tyurina;R. Karlstrom;A. Chandrasekhar
锌指转录因子Gli家族介导所有脊椎动物中的刺猬（Hh）信号传导。然而，它们在腹侧神经管模式，特别是运动神经元诱导中的作用似乎在物种间存在差异。例如，脑运动神经元在斑马鱼绕道（gli1−）突变体中基本上丢失，而运动神经元的发育在小鼠单gli和一些双gli敲除中不受影响。有趣的是，一些Hh调节基因（ptc1，net1a，gli1）的表达大多是不受影响的绕道突变后脑，这表明其他Gli转录激活因子可能参与。为了更好地定义的斑马鱼GLI基因在运动神经元诱导和在HH调节的基因表达的作用，我们研究了这些过程中的你太（yot）突变体，编码显性阻遏形式的GLI 2（GLI 2DR），和以下吗啉介导的GLI 1，GLI 2和GLI 3功能的敲低。在所有轴向水平的运动神经元诱导减少yot（gli2DR）突变胚胎。此外，Hh靶基因的表达在所有轴向水平，除了在菱形4也减少，这表明干扰与其他Glis的功能。事实上，yot突变体中吗啡介导的Gli2DR蛋白敲低导致缺陷运动神经元表型的抑制。然而，在野生型胚胎中gli2敲低没有产生可辨别的运动神经元表型，而gli3敲低减少了后脑和脊髓中的运动神经元诱导。值得注意的是，gli2或gli3敲低迂回（gli1−）突变体揭示了Gli2和Gli3激活剂在ptc1表达和脊髓运动神经元诱导中的作用。同样，gli1或gli3敲低yot（gli2DR）突变体导致严重或完全丧失运动神经元，ptc1和net1a的表达，在后脑和脊髓。此外，gli3（而不是gli1）敲除后，yot突变体中gli1的表达大大减少，这表明gli1表达特别需要Gli3激活剂功能。这些观察结果表明，Gli激活剂功能（由gli1，gli2和gli3编码）是必不可少的运动神经元诱导和Hh调节的基因表达在斑马鱼。
The Gli family of zinc-finger transcription factors mediates Hedgehog (Hh) signaling in all vertebrates. However, their roles in ventral neural tube patterning, in particular motor neuron induction, appear to have diverged across species. For instance, cranial motor neurons are essentially lost in zebrafish detour (gli1−) mutants, whereas motor neuron development is unaffected in mouse single gli and some double gli knockouts. Interestingly, the expression of some Hh-regulated genes (ptc1, net1a, gli1) is mostly unaffected in the detour mutant hindbrain, suggesting that other Gli transcriptional activators may be involved. To better define the roles of the zebrafish gli genes in motor neuron induction and in Hh-regulated gene expression, we examined these processes in you-too (yot) mutants, which encode dominant repressor forms of Gli2 (Gli2DR), and following morpholino-mediated knockdown of gli1, gli2, and gli3 function. Motor neuron induction at all axial levels was reduced in yot (gli2DR) mutant embryos. In addition, Hh target gene expression at all axial levels except in rhombomere 4 was also reduced, suggesting an interference with the function of other Glis. Indeed, morpholino-mediated knockdown of Gli2DRprotein in yot mutants led to a suppression of the defective motor neuron phenotype. However, gli2 knockdown in wild-type embryos generated no discernable motor neuron phenotype, while gli3 knockdown reduced motor neuron induction in the hindbrain and spinal cord. Significantly, gli2 or gli3 knockdown in detour (gli1−) mutants revealed roles for Gli2 and Gli3 activator functions in ptc1 expression and spinal motor neuron induction. Similarly, gli1 or gli3 knockdown in yot (gli2DR) mutants resulted in severe or complete loss of motor neurons, and of ptc1 and net1a expression, in the hindbrain and spinal cord. In addition, gli1 expression was greatly reduced in yot mutants following gli3, but not gli1, knockdown, suggesting that Gli3 activator function is specifically required for gli1 expression. These observations demonstrate that Gli activator function (encoded by gli1, gli2, and gli3) is essential for motor neuron induction and Hh-regulated gene expression in zebrafish.