Regulation of directed neuroblast migration by the ECM and MAB-5/Hox

项目摘要 定向细胞迁移是动物用于构建组织的基本形态发生机制， 机关例如，神经嵴细胞在胚胎中长距离迁移并发育成过多的细胞， 包括整个外周神经系统。In C. Q细胞是两侧的神经母细胞， 在经历左右不对称迁移的动物的后外侧区域中。最初，QR在 右侧突出并向前迁移，左侧QL向后。这种最初的定向迁移受到监管， 通过受体分子α-40/DCC和PTP-3/LAR，驱动后移。A左右（L/R） Q细胞中的不对称性导致在QL而不是QR中有活性的α-40和PTP-3，从而导致后 与前向迁移。迁移的第二阶段依赖于Wnt信号传导，并在 第一次Q细胞分裂QL和后代遇到一个后EGL-20/Wnt信号，驱动表达 MAB-5/Hox转录因子，而QR和后代不表达MAB-5。上更后面的位置 QL后代的迁移需要MAB-5，这对于后验Q 后代移民QL和QR经历相同的细胞分裂、迁移和细胞死亡模式， 每个细胞产生三个神经元。Q迁移的阶段是独立的（例如，在mAb-5突变体中，QL初始 迁移到后部是正常的，但Q后代随后向前迁移）。 我们的初步数据表明，QL与QR之间固有的L/R不对称性决定了这些细胞如何 对细胞外基质（ECM）作出反应，这指定了前向和后向迁移。具体而言是 胶原蛋白α1XXIV分子DPY-17指导向后迁移。DPY-17广泛表达于 动物，而不是其他ECM相关的指导线索（ESTA-6/Netrin，ESTA-1/Slit）表达的具体 引导地区移民。可能是ECM本身的结构提供了前后引导 信息发送到Q小区，并且RTP-40/DCC和PTP-3/LAR解释该信息。我们将测试这个想法， 分析DPY-17和其他ECM成分在初始Q偏移中的作用。初始迁移后，mAb-5/Hox QL中的表达指导向后迁移。mAb-5/Hox是一个末端选择基因， 后移，而不是细胞分裂、死亡或神经元分化的其他方面。我们就来 功能基因组方法来定义MAB-5/Hox末端下游的转录盒 引导后移的选择器。该提案利用了尖端的技术组合（例如， 荧光激活细胞分选（fluorescence-activated cell sorting，FACS）检测C. elegans细胞和RNA-seq），并利用 梭发现科学中的elegans系统。它有可能大大推进实现 详细了解一个简单的发展决定，迁移后方与前方。 Q细胞所使用的机制可能调节参与神经嵴的定向细胞迁移， 神经发育障碍

Project Summary Directed cell migration is a fundamental morphogenetic mechanism used by animals to build tissues and organs. For example, neural crest cells migrate long distances in the embryo and develop into a plethora of cell types, including the entire peripheral nervous system. In C. elegans, the Q cells are bilateral neuroblasts born in the posterior-lateral region of the animal that undergo left-right asymmetric migration. Initially, QR on the right protrudes and migrates anteriorly, and QL on the left posteriorly. This initial directed migration is regulated by the receptor molecules UNC-40/DCC and PTP-3/LAR, which drive posterior migration. A left-right (L/R) asymmetry in the Q cells results in UNC-40 and PTP-3 being active in QL but not QR, leading to posterior versus anterior migration, respectively. The second phase of migration relies on Wnt signaling and begins after the first Q cell division. QL and descendants encounter a posterior EGL-20/Wnt signal that drives expression of the MAB-5/Hox transcription factor, whereas QR and descendants do not express MAB-5. Further posterior migration of the QL descendants requires MAB-5, which is both necessary and sufficient for posterior Q descendant migration. QL and QR undergo an identical pattern of cell division, migration and cell death to generate three neurons apiece. The phases of Q migration are independent (e.g. in mab-5 mutants, QL initial migration to the posterior is normal, but Q descendants then migrate anteriorly). Our preliminary data indicate that an inherent L/R asymmetry in QL versus QR determines how these cells respond to the extracellular matrix (ECM), which specifies anterior versus posterior migration. Specifically, the Collagenα1XXIV molecule DPY-17 directs posterior migration. DPY-17 is expressed broadly throughout the animal, as opposed to other ECM-related guidance cues (UNC-6/Netrin, SLT-1/Slit) expressed in specific regions to direct migration. Possibly, the structure of the ECM itself provides anterior-posterior guidance information to the Q cells, and UNC-40/DCC and PTP-3/LAR interpret this information. We will test this idea by analyzing DPY-17 and other ECM components in initial Q migration. After initial migration, mab-5/Hox expression in QL directs posterior migration. mab-5/Hox is a terminal selector gene which specifically controls posterior migration and not other aspects of cell division, death, or neuronal differentiation. We will take a functional-genomic approach to define a transcriptional cassette downstream of the MAB-5/Hox terminal selector that directs posterior migration. This proposal utilizes a cutting-edge combination of techniques (e.g. fluorescence-activated cell sorting (FACS) of C. elegans cells and RNA-seq), and leverages the strengths of the C. elegans system in discovery science. It has the potential to significantly advance the goal of achieving a detailed understanding of a simple developmental decision to migrate posteriorly versus anteriorly. Mechanisms used by the Q cells might regulate directed cell migrations involved in neural crest and neurodevelopmental disorders in humans.