权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Roles of signaling molecules in forebrain morphogenesis

信号分子在前脑形态发生中的作用

基本信息

批准号：
20590169
负责人：
ISHIBASHI Makoto
金额：
$ 3.08万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2008
资助国家：
日本
起止时间：
2008 至 2010
项目状态：
已结题

项目摘要

Sonic hedgehog (Shh) function is essential for patterning and cell fate specification, particularly in ventral regions of the central nervous system. It is also a crucial mitogen for cerebellar granule neuron precursors and is important in maintenance of the stem cell niche in the postnatal telencephalon. Although it has been reported that Shh is expressed in the developing dorsal telencephalon, functions of Shh in this region are unclear, and detailed characterization of Shh mRNA transcripts in situ has not been demonstrated. To clarify the roles of Shh signaling in dorsal pallium (neocortex primordium) development, we have knocked out the Shh and Smo genes specifically in the early developing dorsal telencephalon by using Emx1cre mice. The mutants showed a smaller dorsal telencephalon at E18.5, which was caused by cell cycle kinetics defects of the neural progenitor/stem cells. The cell cycle length of the progenitor/stem cells was prolonged, and the number of cycle-exiting cells and … More neurogenesis were decreased. Birth-date analysis revealed abnormal positioning of neurons in the mutants. The characteristics of the subventricular zone, ventricular zone and subplate cells were also affected. Weak immunoreactivity of Shh was detected in the dorsal telencephalon of wild types. Reduced Shh immunoreactivity in mutant dorsal telencephalons supports the above phenotypes. Our data indicate that Shh signaling plays an important role in development of the neocortex.Accumulating evidence suggests that Sonic hedgehog (Shh) signaling plays a crucial role in eye vesicle patterning in vertebrates. Shh promotes expression of Pax2 in the optic stalk and represses expression of Pax6 in the optic cup. Shh signaling contributes to establishment of both proximal-distal and dorsal-ventral axes by activating Vax1, Vax2, and Pax2. In the dorsal part of the developing retina, Bmp4 is expressed and antagonizes the ventralizing effects of Shh signaling through the activation of Tbx5 expression in chick and Xenopus. To examine the roles of Shh signaling in optic cup formation and optic stalk development, we utilized the Smoothened (Smo) conditional knockout (CKO) mouse line. Smo is a membrane protein which mediates Shh signaling into inside of cells. Cre expression was driven by Fgf15 enhancer. The ventral evagination of the optic cup deteriorated from E10 in the Smo-CKO, whereas the dorsal optic cup and optic stalk develop normally until E11. We analyzed expression of various genes such as Pax family (Pax2/Pax6), Vax family (Vax1/Vax2) and Bmp4. Bmp4 expression was greatly upregulated in the optic vesicle by the 21-somite stage. Then Vax1/2 expression was decreased at the 20- to 24-somite stages. Pax2/6 expression was affected at the 27- to 32-somite stages. Our data suggest that the effects of the absence of Shh signaling on Vax1/Vax2 are mediated through increased Bmp4 expression throughout the optic cup. Also unchanged patterns of Raldh2 and Raldh3 suggest that retinoic acid is not the downstream to Shh signaling to control the ventral optic cup morphology. Less

Sonic hedgehog（Shh）功能对于图案化和细胞命运规范是必不可少的，特别是在中枢神经系统的腹侧区域。它也是小脑颗粒神经元前体细胞的重要有丝分裂原，在维持出生后端脑干细胞生态位中起重要作用。虽然据报道，Shh在发育中的端脑背侧表达，但Shh在该区域的功能尚不清楚，Shh mRNA转录物原位的详细表征尚未得到证实。为了阐明Shh信号在背侧软腭（新皮层原基）发育中的作用，我们使用Emx 1cre小鼠特异性地敲除了端脑背侧发育早期的Shh和Smo基因。突变体在E18.5时显示出较小的端脑背侧，这是由神经祖细胞/干细胞的细胞周期动力学缺陷引起的。祖细胞/干细胞的细胞周期长度延长，并且周期退出细胞的数量和 ...更多信息神经发生减少。最新的分析显示异常定位的神经元的突变体。室管膜下区、室管膜区和亚板细胞的特征也受到影响。Shh在野生型端脑背侧的免疫反应性较弱。突变体端脑背侧的Shh免疫反应性降低支持上述表型。我们的数据表明Shh信号在新皮层的发育中起着重要的作用，越来越多的证据表明Sonic hedgehog（Shh）信号在脊椎动物眼泡的形成中起着至关重要的作用。Shh促进视柄中Pax 2的表达，抑制视杯中Pax 6的表达。Shh信号通过激活Vax 1、Vax 2和Pax 2来促进近端-远端轴和背腹轴的建立。在发育中的视网膜的背侧部分中，Bmp 4表达并通过激活Tbx 5在鸡和爪蟾中的表达来拮抗Shh信号传导的腹侧效应。为了研究Shh信号传导在视杯形成和视柄发育中的作用，我们利用Smoothened（Smo）条件性敲除（CKO）小鼠系。Smo是介导Shh信号进入细胞内部的膜蛋白。Cre表达由Fgf 15增强子驱动。Smo-CKO的视杯腹侧外翻从E10开始恶化，而背侧视杯和视柄正常发育，直到E11。我们分析了各种基因的表达，如Pax家族（Pax 2/Pax 6），Vax家族（Vax 1/Vax 2）和Bmp 4。bmp 4的表达大大上调，在视泡的21体节阶段。Vax 1/2在20- 24体节期表达下降。Pax 2/6的表达在27- 32体节期受到影响。我们的数据表明，在Vax 1/Vax 2的Shh信号的情况下，通过增加整个视杯的Bmp 4表达介导的影响。同样，Raldh 2和Raldh 3的不变模式表明视黄酸不是Shh信号的下游以控制腹侧视杯形态。少