Regulating the scaling of growth and pattern during neural development

调节神经发育过程中的生长规模和模式

• 批准号: RGPIN-2020-03925
• 负责人: Iulianella, Angelo
• 金额: $ 2.33万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=716142
• 关键词: Regulating; scaling; growth; pattern; during

Tissue formation requires the coordination of two fundamental cellular processes: growth and patterning. Within the nervous system the initial driver of growth and patterning are signaling factors called morphogens. They activate gene regulatory networks to specify distinct cell fates within the developing central nervous system (CNS) and sculpt the size and boundaries to tissues and organs during development. Thus, a clear understanding of how morphogens can accomplish these feats of tissue engineering is of central importance to developmental biology. Three key morphogenetic pathways that regulate tissue growth and survival are those regulated by the secreted proteins Sonic Hedgehog (Shh), Wingless/Int-related (Wnt), and Bone Morphogenetic Protein (BMP). Work from our group has revealed the intricate relationship between Shh and Wnt signaling during craniofacial and nerve development. We generated a series of unique mouse mutants that carefully titrated the levels Shh signaling during development. We discovered that excessive Shh signaling leads to a restriction Wnt signaling and growth promoting pathways in craniofacial primordia, resulting in hypoplasia. We also showed that if Shh levels are too high, cell death occurs in migrating neural crest cells and prevents their integration with placode cells during sensory ganglia formation. Therefore, the appropriate levels of Shh signaling is required to ensure the coordination of growth signals with cell fate acquisition in developing tissues. It is however unclear how Shh levels act to achieves this balance, and answering this question will shed light on how growth and specification can scale according to the widely divergent body sizes in vertebrates. The proposed research program will take advantage of our Shh pathway mutants to generate a 'scalable' spinal organoid model system to test the relationship between growth and patterning. Growth dynamics will be correlated with a mapping of the developmental trajectories of neural cell subtypes using single cell RNA sequencing technology. A complimentary approach involves removing a key growth promoting checkpoint control gene within the context of altered Shh signaling levels and evaluate its effect on the growth and pattering of the nervous system. This genetic approach will also label Shh-positive tissues with green fluorescent protein, allowing for an analysis of dynamic cellular and molecular events underpinning growth control and patterning by the Shh mophogen gradient. We will then identify the gene networks that regulate the decision branch points involved in coordinating growth control and cell specification in the neural tissues. In so doing our research program will address a long-standing problem in evolutionary developmental biology, the scaling of 'growth and form', and will also make contributions to the lives of Canadians by optimizing methodologies for the generation of functional tissues suitable for replacement therapies.

组织形成需要协调两个基本的细胞过程：生长和模式化。在神经系统内，生长和模式形成的最初驱动力是称为形态发生素的信号因子。它们激活基因调控网络，以指定发育中的中枢神经系统（CNS）内不同的细胞命运，并在发育过程中塑造组织和器官的大小和边界。因此，清楚地了解形态发生素如何完成组织工程的这些壮举对于发育生物学至关重要。 调节组织生长和存活的三个关键形态发生途径是由分泌蛋白 Sonic Hedgehog (Shh)、Wingless/Int 相关 (Wnt) 和骨形态发生蛋白 (BMP) 调节的。我们小组的工作揭示了颅面和神经发育过程中 Shh 和 Wnt 信号之间的复杂关系。我们生成了一系列独特的小鼠突变体，在发育过程中仔细滴定了 Shh 信号传导水平。我们发现过度的Shh信号传导会导致颅面原基中的Wnt信号传导和生长促进途径受到限制，从而导致发育不全。我们还表明，如果Shh水平过高，迁移的神经嵴细胞就会发生细胞死亡，并阻止它们在感觉神经节形成过程中与基板细胞整合。因此，需要适当水平的Shh信号来确保生长信号与发育组织中细胞命运获取的协调。然而，目前尚不清楚Shh水平如何实现这种平衡，回答这个问题将有助于揭示脊椎动物的生长和规格如何根据差异很大的体型进行调整。拟议的研究计划将利用我们的 Shh 通路突变体来生成“可扩展”的脊柱类器官模型系统，以测试生长和模式之间的关系。生长动态将与使用单细胞 RNA 测序技术绘制的神经细胞亚型发育轨迹图谱相关联。一种补充方法涉及在改变的Shh信号水平的背景下去除关键的生长促进检查点控制基因，并评估其对神经系统生长和模式的影响。这种遗传方法还将用绿色荧光蛋白标记Shh阳性组织，从而可以分析支持Shh形态发生梯度的生长控制和模式的动态细胞和分子事件。然后，我们将识别调节决策分支点的基因网络，这些决策分支点涉及协调神经组织中的生长控制和细胞规范。在此过程中，我们的研究计划将解决进化发育生物学中长期存在的问题，即“生长和形态”的扩展，并将通过优化适合替代疗法的功能组织的生成方法，为加拿大人的生活做出贡献。