Cell motility in vivo - polarization of zebrafish germ cells

发育生物学的一个中心主题是在模式形成和器官发生过程中细胞和组织的运动。确定促进体内细胞极化和迁移的分子和细胞机制将有助于我们对各种发育过程的理解。斑马鱼原始生殖细胞的迁移是研究细胞迁移的一个很好的活体模型。这些细胞的迁移路径，负责指导它们的分子和一些促进细胞运动的细胞机制是已知的。这些知识将用于拟议的研究，旨在解决在细胞运动背景下获得细胞极性的问题。丝状足是细胞的细长延伸，包含平行的肌动蛋白丝，通常在迁移细胞表面观察到。尽管丝状足被认为在细胞迁移中起作用，但它们在完整生物体中的确切功能迄今尚不清楚。在本研究过程中，将监测丝状足在迁移过程的不同阶段（获得运动性、定向迁移和到达目标后停止）的分布和形态。不同的调节因子和结构蛋白在丝状足中的分布将在这些不同的迁移阶段被确定。下一步，将使用过表达或表达修饰蛋白版本来影响丝状足的发育（丝状足的分布、长度和稳定性）。丝状伪足结构的改变对细胞运动重要的生化途径（钙信号、肌动蛋白分布、septin极化和RhoGTPases的激活模式）的影响将被确定。最后，将比较野生型细胞和丝状足发育受损的细胞之间的细胞迁移动态参数。具体来说，我们将研究异常丝状足对细胞迁移速度、方向维持和到达目标的影响。

A central theme in Developmental Biology is the movement of cells and tissues during pattern formation and organogenesis. Determining the molecular and cellular mechanisms facilitating cell polarization and migration in vivo would thus contribute to our understanding of various developmental processes. The migration of zebrafish primordial germ cells serves as an excellent accessible in vivo model for cell migration. The migration path of these cells, the molecules responsible for directing them and some of the cellular mechanisms facilitating cell motility are known. This knowledge will be employed in the proposed research that is aimed at addressing the issue of the acquisition of cell polarity in the context of cell motility. Filopodia are thin cellular extensions containing parallel actin filaments that are often observed on the surface of migratory cells. Whereas filopodia are thought to play a role in cell migration, their precise function in the context of the intact organism is so far unknown. In the course of this study, the distribution and the morphology of filopodia will be monitored during different steps of the migration process (acquisition of motility, directed migration and stop upon arrival at the target). The distribution of different regulators and structural proteins in the filopodia will then be determined at those different phases of migration. In the next step, over-expression or expression of modified protein versions will be used to affect filopodia development (filopodia distribution, length and stability). The effect of alterations in filopodia structure on biochemical pathways (calcium signaling, actin distribution, septin polarization and the activation patterns of RhoGTPases) important for cell motility will be determined. Last, dynamic parameters of cell migration will be compared between wild-type cells and cells in which filopodia development is compromised. Specifically, we will examine the effect of abnormal filopodia on cell migration speed, maintenance of direction and arrival at the target.