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Analysis on molecular mechanisms of neuralization and early patterning in the formation of the presumptive midbrain-hindbrain boundary region

假定中脑-后脑边界区域形成中神经化和早期模式形成的分子机制分析

基本信息

批准号：
16370076
负责人：
TAIRA Masanori
金额：
$ 9.92万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

To explore the molecular mechanism of neuralization and early pattern formation in vertebrate embryos, we investigated the following two subjects.1) Functional analysis of XHR1 : ESR1 is a bHLH transcriptional repressor gene, and was identified as a candidate for XHR1 target genes. We performed (1) gene activation analysis using a XRH1-VP16-GR construct and a protein synthesis inhibitor, (2) gain-of-function analysis of XHR1 and ESR1, and (3) loss-of-function analysis using antisense-morpholino oligos for XHR1. We showed that ESR is a direct target of XHR1 ; that XHR1 is necessary and sufficient for suppression of ESR1 expression; and that overexpression of ESR1 represses the MHB gene Pax2. Furthermore, in contrast to ESR1, XHR1 was not activated by Notch signaling, and XHR1 directly repressed neuronal genes, neurogenin and delta. These data suggest that XHR1 functions as a prepattern gene for MHB formation as well as for proneural cluster formation by repressing neuronal differentiati … More on2) Analysis of XHR1 gene regulation : We cloned and analyzed a Xenopus tropicalis HR1 (XtHR1) promoter, which faithfully recapitulated the endogenous XHR1 expression. Surprisingly, transgenic and animal cap assays revealed distinct enhancers, named the early and late enhancer modules (the EEM and LEM), that govern XHR1 expression in pre-MHB and MHB regions, respectively. Furthermore, the EEM was found to integrate Noggin, Wnt, and FGF signals. Gain-of-function and dominant-negative approaches in vivo showed that neural inducers activate XHR1 ; Wnt signaling confines XHR1 expression; and moderate and strong FGF signaling enhances and suppresses XHR1 expression, respectively. These data suggest that the XHR1 expression of the pre-MHB region is induced through the EEM by signaling molecules from the Spemann organizer.Thus, we have shown the molecular mechanism of XHR1 induction in the pre-MHB region and a molecular cascade mediated by XHR1 from the pre-MHB to the MHB region, an organizing center of brain formation. Less

为了探讨脊椎动物胚胎神经化和早期模式形成的分子机制，我们研究了以下两个方面：1）XHR 1的功能分析：ESR 1是一个bHLH转录抑制基因，被确定为XHR 1靶基因的候选基因。我们进行了（1）使用XRH 1-VP 16-GR构建体和蛋白质合成抑制剂的基因激活分析，（2）XHR 1和ESR 1的功能获得分析，以及（3）使用XHR 1的反义吗啉代寡核苷酸的功能丧失分析。我们发现ESR是XHR 1的直接靶点; XHR 1是抑制ESR 1表达的必要和充分条件; ESR 1的过表达抑制MHB基因Pax 2。此外，与ESR 1相反，XHR 1不被Notch信号激活，并且XHR 1直接抑制神经元基因neurogenin和delta。这些数据表明，XHR 1通过抑制神经元分化，作为MHB形成以及前神经簇形成的前模式基因发挥作用。 ...更多信息（2）XHR 1基因调控分析：克隆并分析了热带爪蟾（Xenopus tropicalis）HR 1（XtHR 1）启动子，该启动子忠实地再现了XHR 1的内源表达。令人惊讶的是，转基因和动物帽分析揭示了不同的增强子，称为早期和晚期增强子模块（EEM和LEM），分别控制前MHB和MHB区域中的XHR 1表达。此外，发现EEM整合Noggin、Wnt和FGF信号。体内功能获得和显性负性方法表明，神经诱导剂激活XHR 1; Wnt信号传导限制XHR 1表达;中度和强烈的FGF信号传导分别增强和抑制XHR 1表达。这些数据表明，XHR 1的表达pre-MHB区域通过EEM由Spemann organizer的信号分子诱导，因此，我们已经展示了XHR 1在pre-MHB区域诱导的分子机制和XHR 1介导的从pre-MHB到MHB区域的分子级联反应，MHB区域是脑形成的组织中心。少

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Systematic screening for genes specifically expressed in the anterior neuroectoderm during early Xenopus development

系统筛选爪蟾早期发育过程中前神经外胚层特异表达的基因

DOI：
发表时间：
2005
期刊：
Int.J.Dev.Biol. 49
影响因子：
0
作者：
Takada;H.;Hattori;D.;Kitayama;A.;Ueno;N.;Taira;M.;Hitomi Takada;Mikihito Shibata;Noriyuki Takahashi
通讯作者：
Noriyuki Takahashi

Identification of target genes for the Xenopus Hes-related protein XHR1, a prepattern factor specifying the midbrain-hindbrain boundary