Heterogeneity of forebrain neural precursors

描述（由申请人提供）：发育神经生物学的两个主要目标是鉴定形成中枢神经系统的生殖细胞，并表征这些细胞产生适当数量和类型的神经元和神经胶质细胞的细胞和分子机制。最近，逆转录病毒和遗传学研究表明，放射状胶质细胞（RGC）的新皮质发育显着的有丝分裂后产生的神经元，然后作为这些子细胞迁移到新皮质壁的基板。此外，RGCs现在被认为是新皮质的产前干细胞，并且一些研究小组已经提出，在胚胎神经发生期间，新皮质脑室区（VZ）仅由RGCs组成。然而，目前还不清楚一个单一的VZ前体细胞类型如何产生新皮层神经元的巨大多样性。此外，由于在人类和猴VZ中发现了多种类型的前体，灵长类VZ中的这种异质性是否代表啮齿类和灵长类的进化分歧也仍然是一个问题。 我们已经发现在体内鼠VZ的显着的前体多样性。通过使用多种组织学，遗传学和超微结构技术-其中许多是我们为这个项目创新的-我们现在表明，RGCs加入了另一种类型的常驻VZ细胞，我们命名为短神经前体细胞（SNP）。我们证明，RGCs和SNPs可以区分形态，分子，以及相对于增殖动力学和谱系潜力。此外，我们已经发现了RGCs类别之间的体内差异，这表明并非所有的RGCs都是多能干细胞。两者合计，我们公布的初步数据从根本上改变了我们的理解哺乳动物VZ的组成，并清楚地表明，在这个germinal隔间的多样性是必要的适当的新皮层的生长和功能。该项目将全面测试的整体假设，即VZ成为异质性在胚胎发育过程中通过多样化的共同VZ祖先，这种复杂性是必要的适当的新皮层生长。 公共卫生相关性：在发育过程中，前脑神经元类型的丰富多样性是如何实现的，目前还不清楚。在这个项目中，我们建立在我们的新发现，即不同类型的神经干细胞和祖细胞存在于胚胎脑中，并通过不同的机制产生神经元。使用在体内的分子方法来测量增殖，神经发生和分配的后代从个别前体组，本研究将揭示这些前体细胞之间的时空相互关系，并确定如何与细胞外基质的相互作用在生发区控制其神经元的输出。

DESCRIPTION (provided by applicant): Two major goals of developmental neurobiology are to identify the germinal cells which form the central nervous system and to characterize the cellular and molecular mechanisms by which these cells generate the proper numbers and types of neurons and glial cells. Recently, retroviral and genetic studies in mice have demonstrated that radial glial cells (RGCs) contribute significantly to neocortical development by generating postmitotic neurons and then serving as the substrate for the migration of those daughter cells into the neocortical wall. Furthermore, RGCs are thought now to be the prenatal stem cell of the neocortex, and several groups have suggested that the neocortical ventricular zone (VZ) is composed solely of RGCs during embryonic neurogenesis. However, it remains unclear how a single VZ precursor cell type can generate the vast diversity of neocortical neurons. In addition, since multiple types of precursors have been found in the human and monkey VZ, whether this heterogeneity in the primate VZ represents evolutionary divergence of rodents and primates also remains a question. We have uncovered significant precursor diversity in the in vivo murine VZ. Through the use of multiple histological, genetic and ultrastructural techniques - many of which we innovated for this project - we now show that RGCs are joined by another type of resident VZ cell which we have named the short neural precursor cell (SNP). We demonstrate that RGCs and SNPs can be distinguished morphologically, molecularly, and with respect to proliferation kinetics and lineage potential. In addition, we have uncovered in vivo differences between classes of RGCs which suggest that not all RGCs are multipotent stem cells. Taken together, our published and Preliminary Data fundamentally alter our understanding of the composition of the mammalian VZ and clearly indicate that diversity in this germinal compartment is required for proper neocortical growth and function. This project will comprehensively test the overall hypothesis that the VZ becomes heterogeneous during embryonic development through diversification of a common VZ ancestor and that this complexity is necessary for proper neocortical growth. PUBLIC HEALTH RELEVANCE: How the rich diversity in types of forebrain neurons is achieved during development is not well understood. In this project, we build upon our novel findings that different types of neural stem and progenitor cells exist in the embryonic brain and generate neurons via distinct mechanisms. Using in vivo molecular approaches to measure proliferation, neurogenesis and allocation of progeny from individual precursor groups, this study will uncover the spatiotemporal inter-relationships between these precursor cells and determine how interaction with the extracellular matrix in the germinal zone controls their neuronal output.