Midbrain-hindbrain boundary patterning and morphogenesis are regulated by diverse grainy head-like 2-dependent pathways
Midbrain-hindbrain boundary patterning and morphogenesis are regulated by diverse grainy head-like 2-dependent pathways
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DOI：
10.1242/dev.066522
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发表时间：
2012-02-01
期刊：
影响因子：
4.6
通讯作者：
Jane, Stephen M.
中科院分区：
文献类型：
--
作者：
Dworkin, Sebastian;Darido, Charbel;Jane, Stephen M.
位于中脑-后脑边界（MHB）的峡部组织者是负责脊椎动物大脑中脑和后脑区域图案化的关键发育信号中心。MHB的形成和维持的特征是由成纤维细胞生长因子8（Fgf 8）启动的基因表达分层程序，加上细胞形态发生，最终形成顶盖-峡部-小脑结构。在这里，我们表明，在斑马鱼的转录因子颗粒状头样2（Grhl 2），斑马鱼grhl 2b的一个直系同源物在MHB的维护和折叠中起着核心作用，通过调节两个不同的，非线性的途径。grhl 2b表达的丧失诱导神经细胞凋亡和MHB标志物的消失，其通过重新表达Grailed 2a（eng 2a）（Grhl家族的进化上保守的靶标）来挽救。共注射亚表型剂量的grhl 2b和eng 2a吗啉代再现了细胞凋亡和MHB标志物损失，但未能基本上破坏峡部缩窄的形成。相比之下，一种新的直接grhl 2b目标，spec 1，通过系统发育分析和ChIP确认，功能上与grhl 2b合作，诱导MHB形态发生，但在细胞凋亡或MHB标记的维持中不起作用。总的来说，这些数据表明，MHB维持和形态发生是由grhl 2b通过不同的转录靶调控的可分离事件。
The isthmic organiser located at the midbrain-hindbrain boundary (MHB) is the crucial developmental signalling centre responsible for patterning mesencephalic and metencephalic regions of the vertebrate brain. Formation and maintenance of the MHB is characterised by a hierarchical program of gene expression initiated by fibroblast growth factor 8 (Fgf8), coupled with cellular morphogenesis, culminating in the formation of the tectal-isthmo-cerebellar structures. Here, we show in zebrafish that one orthologue of the transcription factor grainy head-like 2 (Grhl2), zebrafish grhl2b plays a central role in both MHB maintenance and folding by regulating two distinct, non-linear pathways. Loss of grhl2b expression induces neural apoptosis and extinction of MHB markers, which are rescued by re-expression of engrailed 2a (eng2a), an evolutionarily conserved target of the Grhl family. Co-injection of sub-phenotypic doses of grhl2b and eng2a morpholinos reproduces the apoptosis and MHB marker loss, but fails to substantially disrupt formation of the isthmic constriction. By contrast, a novel direct grhl2b target, spec1, identified by phylogenetic analysis and confirmed by ChIP, functionally cooperates with grhl2b to induce MHB morphogenesis, but plays no role in apoptosis or maintenance of MHB markers. Collectively, these data show that MHB maintenance and morphogenesis are dissociable events regulated by grhl2b through diverse transcriptional targets.