Opposing Shh and Fgf signals initiate nasotemporal patterning of the zebrafish retina.
Opposing Shh and Fgf signals initiate nasotemporal patterning of the zebrafish retina.
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DOI：
10.1242/dev.125120
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发表时间：
2015-11-15
期刊：
影响因子：
--
通讯作者：
Cavodeassi F
中科院分区：
文献类型：
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作者：
Hernández-Bejarano M;Gestri G;Spawls L;Nieto-López F;Picker A;Tada M;Brand M;Bovolenta P;Wilson SW;Cavodeassi F
最早已知的视网膜鼻颞特征的决定因素是转录调节因子 Foxg1（在预期鼻视神经泡中表达）和 Foxd1（在预期颞视神经泡中表达）。先前的研究表明，在斑马鱼中，需要来自背侧前脑和嗅觉原基的 Fgf 信号来指定背侧、预期鼻、视泡中的鼻腔身份。在这里，我们表明来自腹侧前脑的 Hh 信号对于腹侧视泡中的时间特性的规范是必需的，并且当在预期鼻视网膜中激活时足以诱导时间特征。因此，通过前脑原基背侧和腹侧区域发出的 Fgfs 和 Shh 的相反作用，外翻视神经泡被分成预期的鼻区和颞区。在缺乏 Fgf 活性的情况下，无论 Hh 信号传导水平如何，foxd1 的表达都会建立，这表明只有在存在 Fgf 活性的情况下才需要 Shh 在促进 Foxd1 表达中的作用。一旦 Foxd1 和 Foxg1 的空间互补表达建立，表达域之间的边界就通过 Foxd1 和 Foxg1 之间的相互抑制来维持。摘要：在鱼眼中，来自腹侧前脑的 Hh 信号通过促进 Foxd1 表达来调节视网膜的空间特性。仅当存在 Fgf 活性时才需要此作用。
The earliest known determinants of retinal nasotemporal identity are the transcriptional regulators Foxg1, which is expressed in the prospective nasal optic vesicle, and Foxd1, which is expressed in the prospective temporal optic vesicle. Previous work has shown that, in zebrafish, Fgf signals from the dorsal forebrain and olfactory primordia are required to specify nasal identity in the dorsal, prospective nasal, optic vesicle. Here, we show that Hh signalling from the ventral forebrain is required for specification of temporal identity in the ventral optic vesicle and is sufficient to induce temporal character when activated in the prospective nasal retina. Consequently, the evaginating optic vesicles become partitioned into prospective nasal and temporal domains by the opposing actions of Fgfs and Shh emanating from dorsal and ventral domains of the forebrain primordium. In absence of Fgf activity, foxd1 expression is established irrespective of levels of Hh signalling, indicating that the role of Shh in promoting foxd1 expression is only required in the presence of Fgf activity. Once the spatially complementary expression of foxd1 and foxg1 is established, the boundary between expression domains is maintained by mutual repression between Foxd1 and Foxg1. Summary: In the fish eye, Hh signalling from the ventral forebrain regulates spatial identity in the retina by promoting foxd1 expression. This role is required only in the presence of Fgf activity.