Dorsal Signals in the Developing Telencephalon

描述（由申请人提供）：骨形态发生蛋白（Bmps）和wnt代表了两个信号蛋白家族，它们是发育的基本调节因子。在端脑（包含大脑皮层的前脑分支）中，多个Bmps和wnt在背中线区域（DMR）表达，它们可能负责多种发育功能和畸形表型。然而，由于家庭成员之间存在显著的功能冗余，他们的假定角色仍然难以捉摸。这和其他因素极大地降低了传统小鼠遗传学对阐明Bmp和Wnt在端脑发育中的功能的影响。为了克服这一限制，我们采用了另一种成熟的遗传方法——谱系特异性细胞消融。在我们最近改进的系统中，我们利用Bmp家族成员（Gdf7）的限制性表达来消融活小鼠胚胎中的一小部分DMR细胞。这导致多种Bmp和Wnt信号明显减少，这与端脑的三个主要缺陷有关：1)脉络膜丛（脑脊液的产生者）的丧失，2)选择性皮质图案缺陷，以及3)无前脑畸形（HPE），这是人类大脑最常见的先天性畸形。该建议的核心假设是，dmr依赖于远端脑区模式和HPE发病机制的功能是由Bmp和Wnt信号介导的。当前的目标是确定Bmp和Wnt信号在介导DMR的胚胎模式功能中是否必要和充分。我们将通过将小鼠遗传学与外植体培养相结合来解决这一假设，外植体培养将通过标记和定量基因表达研究进行分析。K02职业发展活动的重点是开发全面的外植体方法和新的DMR消融模型，以允许产后生存。其他人员将咨询并提供与人类HPE相关的信息。这些活动应该有助于候选人制定研究计划的长期目标，以回答早期端脑发育和疾病的基本问题。对人类HPE的深入了解与公共卫生直接相关。此外，该项目将为了解涉及Bmp和Wnt信号的其他人类大脑疾病奠定基础。

DESCRIPTION (provided by applicant): The bone morphogenetic proteins (Bmps) and Wnts represent two families of signaling proteins that are fundamental regulators of development. In the telencephalon - the forebrain subdivision that contains the cerebral cortex - multiple Bmps and Wnts are expressed in the dorsal midline region (DMR), where they are likely responsible for multiple developmental functions and malformation phenotypes. However, their presumed roles have remained elusive, due in part to significant functional redundancy among family members. This and other factors have greatly minimized the impact of traditional mouse genetics on elucidating Bmp and Wnt functions in telencephalic development. To overcome this limitation, we have adopted an alternative, but well established, genetic approach - lineage-specific cellular ablation. In our recently improved system, we utilize the restricted expression of a Bmp family member (Gdf7) to ablate a small subset of DMR cells in living mouse embryos. This causes marked reductions of multiple Bmp and Wnt signals, which are associated with three major defects in the telencephalon: 1) Loss of choroid plexus, the producer of cerebrospinal fluid, 2) selective cortical patterning defects, and 3) holoprosencephaly (HPE), the most common congenital malformation of the human brain. The central hypothesis driving this proposal is that DMR-dependent functions in telencephalic patterning and HPE pathogenesis are mediated by Bmp and Wnt signals. The immediate goal is to determine whether Bmp and Wnt signals are necessary and sufficient to mediate the embryonic patterning functions of the DMR. We will address this hypothesis by combining mouse genetics with explant cultures, which will be analyzed with markers and quantitative gene expression studies. K02 career development activities focus on developing a comprehensive explant approach and new DMR ablation models that allow for postnatal survival. Other personnel will consult and provide relevance to human HPE. These activities should facilitate the candidate's long-term goal of developing a research program that answers fundamental questions in early telencephalic development and disease. The insights into human HPE provide immediate relevance to public health. In addition, this project should lay the groundwork for understanding other human brain disorders that involve Bmp and Wnt signals.