Gene regulatory networks underlying the compartmentalization of the Ciona central nervous system
Gene regulatory networks underlying the compartmentalization of the Ciona central nervous system
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DOI：
10.1242/dev.026419
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发表时间：
2009-01-15
期刊：
影响因子：
4.6
通讯作者：
Satou, Yutaka
中科院分区：
文献类型：
--
作者：
Imai, Kaoru S.;Stolfi, Alberto;Satou, Yutaka
中枢神经系统（CNS）的三重结构可能是双侧肌的一个古老特征。然而，更复杂的脊椎动物大脑的加工取决于中脑-后脑边界（MHB）组织者，这在无脊椎动物如果蝇中是不存在的。在MHB组织者中表达的Fgf 8信号传导分子在描绘脊椎动物CNS中单独的中脑和后脑区室中起关键作用。在这里，我们提出的证据表明，FGF 8直系同源物建立在发展中的后部感觉囊泡的调控基因表达的顺序模式，和位于简单的脊索动物玻璃海鞘的感觉囊泡和内脏神经节之间的交错的“颈部”区域。在发育中的CNS中基因网络的详细表征导致了对Fgf 8/17/18模式化脊索动物大脑的机制的新见解。这种FGF信号传导活性的精确定位取决于调节Snail的不寻常的AND/OR网络基序，Snail编码Fgf 8表达的阈值阻遏物。Nodal足以激活神经板内低水平的Snail阻遏物，而Nodal和Neurogenin的组合在CNS的相邻结构域中产生高水平的Snail。Fgf 8图案活性的丧失导致海鞘和脊椎动物的后脑结构转变为扩大的中脑，这表明原始的MHB样活性早于脊椎动物的中枢神经系统。发展
The tripartite organization of the central nervous system (CNS) may be an ancient character of the bilaterians. However, the elaboration of the more complex vertebrate brain depends on the midbrain-hindbrain boundary (MHB) organizer, which is absent in invertebrates such as Drosophila. The Fgf8 signaling molecule expressed in the MHB organizer plays a key role in delineating separate mesencephalon and metencephalon compartments in the vertebrate CNS. Here, we present evidence that an Fgf8 ortholog establishes sequential patterns of regulatory gene expression in the developing posterior sensory vesicle, and the interleaved 'neck' region located between the sensory vesicle and visceral ganglion of the simple chordate Ciona intestinalis. The detailed characterization of gene networks in the developing CNS led to new insights into the mechanisms by which Fgf8/17/18 patterns the chordate brain. The precise positioning of this Fgf signaling activity depends on an unusual AND/OR network motif that regulates Snail, which encodes a threshold repressor of Fgf8 expression. Nodal is sufficient to activate low levels of the Snail repressor within the neural plate, while the combination of Nodal and Neurogenin produces high levels of Snail in neighboring domains of the CNS. The loss of Fgf8 patterning activity results in the transformation of hindbrain structures into an expanded mesencephalon in both ascidians and vertebrates, suggesting that the primitive MHB-like activity predates the vertebrate CNS. DEVELOPMENT