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。因此，确定促进细胞极化和迁移的分子和细胞机制将有助于我们理解各种发育过程。斑马鱼原始生殖细胞的迁移作为一个很好的可访问的体内细胞迁移模型。这些细胞的迁移路径、负责引导它们的分子和促进细胞运动的一些细胞机制是已知的。这些知识将被用于拟议的研究，旨在解决细胞运动背景下细胞极性的获取问题。丝状伪足是一种细长的细胞延伸物，含有平行的肌动蛋白丝，常在迁移细胞表面观察到。虽然丝状伪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为止尚不清楚。在本研究过程中，将在迁移过程的不同步骤（获得运动性、定向迁移和到达靶点后停止）期间监测丝状伪足的分布和形态。然后将确定在这些不同的迁移阶段中丝状伪足中不同调节剂和结构蛋白的分布。在下一步中，过表达或修饰的蛋白质形式的表达将用于影响丝状伪足发育（丝状伪足分布、长度和稳定性）。将确定丝状伪足结构的改变对细胞运动重要的生化途径（钙信号传导、肌动蛋白分布、隔蛋白极化和RhoGTP酶的激活模式）的影响。最后，将在野生型细胞和其中丝状伪足发育受损的细胞之间比较细胞迁移的动态参数。具体来说，我们将研究异常丝状伪足对细胞迁移速度，方向的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.