Investigating how sequentially acting cues guide long-distance cell migration in vivo within embryos

总结 集体细胞迁移对于正常胚胎发育和器官发生的进展是必不可少的， 并且是一个严格调节的过程，可能涉及两种或多种信号通路之间的相互作用， 推动细胞群向前移动。此外，器官的模式化通常需要选择性凋亡 和细胞的代偿性增殖。集体迁移和细胞死亡程序中的错误可能会导致严重的 结果，包括完全发育停滞，器官功能异常和肿瘤发生。在这 提出的研究计划，我们将使用果蝇胚胎尾部内脏中胚层（CVM），一个小的 一群肌肉前体细胞，经历高度定型的定向运动，作为模型， 集体细胞迁移和存活。作为胚胎发生过程中最长的迁移过程，CVM细胞必须接受输入 通过来自其他细胞的信号线索，以便在发育中的胚胎中导航不断变化的环境。 我们先前已经确定FGF信号作为趋化性和存活线索的重要作用， FGF受体在迁移细胞中特异性表达。然而，FGF信号转导的缺失 没有完全消除集体迁移，这表明存在额外的，尚未定性的 线索本研究的目的是全面了解时空调控 引导CVM定向运动的线索，以及随后的不同亚群的存活或凋亡， 细胞我们的中心假设是，FGF信号与其他信号线索合作，以驱动 前向运动和细胞存活，并涉及在每个CVM队列中定义专门的细胞子集 促进空间组织，推动向前运动。为了验证这一假设，我们将进行以下研究： 具体目标：（目的1）研究迁移的CVM集体中空间定位基因的作用， 促进细胞迁移;（AIM 2）研究CVM吸引PGCs的机制;（AIM 3）研究 BMP和FGF信号在调节CVM细胞迁移和存活中的关系。完成 为了实现这些目标，我们将采用一种创新的方法，将已建立的遗传学和免疫染色技术相结合， 利用先进的光遗传学和活体成像方法来操纵和可视化迁移细胞， 以及量化细胞死亡程序的时空激活。我们认为这项研究意义重大 因为它不仅展示了一种新兴的信号串扰机制， 细胞迁移系统特征不佳，但考虑到大量的功能和疾病 归因于信号通路如BMP和FGF，阐明了多个通路之间的相互作用 在遗传上易于处理和保守的果蝇模型系统的背景下， 更具体的治疗目标。因此，这项研究将通过促进更多的 全面了解集体细胞迁移，器官发生的机制，以及 与正常发育和癌症有关的细胞迁移和存活程序。

SUMMARY Collective cell migration is essential to the progression of normal embryonic development and organogenesis, and is a tightly-regulated process that can involve the interplay between two or more signaling pathways to drive forward movement of cell cohorts. Additionally, patterning an organ often requires selective apoptosis and compensatory proliferation of cells. Errors in collective migration and cell death programs can have serious consequences, including complete developmental arrest, abnormal organ function, and tumorigenesis. In this proposed research plan, we will use the Drosophila embryonic caudal visceral mesoderm (CVM), a small population of muscle precursor cells that undergo highly stereotyped directional movement, as a model for collective cell migration and survival. As the longest migration of embryogenesis, CVM cells must receive input via signaling cues from other cells in order to navigate the changing environment of the developing embryo. We have previously determined an important role for FGF signaling as both chemotropic and survival cue, and that FGF receptor is specifically expressed in a subset of migratory cells. However, loss of FGF signaling does not completely ablate collective migration, suggesting the existence of additional, as-of-yet uncharacterized cues. The objective of this study is to gain a comprehensive understanding of the spatiotemporally-regulated cues that guide directional movement of the CVM, and subsequent survival or apoptosis of distinct subsets of cells. Our central hypothesis is that FGF signaling cooperates with additional signaling cues in order to drive forward movement and cell survival, and involves defining specialized subsets of cells within each CVM cohort to promote spatial organization driving forward movement. To test this hypothesis, we will pursue the following specific aims: (AIM 1) Investigate roles for spatially-localized genes within the migrating CVM collective in promoting cell migration; (AIM 2) Investigate mechanism of CVM attraction to PGCs; and (AIM 3) Investigate the relationship between BMP and FGF signaling in regulating CVM cell migration and survival. To accomplish these aims, we will employ an innovative combination of established genetics and immunostaining techniques with elegant optogenetics and in vivo live imaging approaches to manipulate and visualize migratory cells, as well as quantify spatiotemporal activation of the cell death program. We believe this study is significant because it would not only demonstrate a mechanism for signaling cross-talk in an emerging yet poorly-characterized cell migration system, but considering the large number of functions and diseases attributed to signaling pathways such as BMP and FGF, elucidating the interaction between multiple pathways in the context of the genetically-tractable and conserved Drosophila model system has the potential to identify more specific therapeutic targets. Therefore, this study will be impactful by contributing to a more comprehensive understanding of collective cell migration, the mechanisms underlying organogenesis, as well as the cell migration and survival programs implicated in normal development and cancer.