Cytokinesis and RNA segregation in zebrafish development

描述（由申请人提供）：母体遗传的种质核糖核颗粒（GP RNP）导致激活一个保守的基因表达程序的原始生殖细胞规范，我们使用斑马鱼作为脊椎动物模型系统来研究这一过程。斑马鱼母系遗传的GP RNP已经增选了细胞骨架机制以达到渐进的多聚化水平：在沟起始之前的聚集（预聚集）、在其起始期间向沟的募集以及沿着沿着沟经历成熟的远端压实。这些连续的过程导致形成四个大质量的聚集的GP RNP，这将最终赋予生殖细胞特化。这个建议的首要假设是，增加GP RNP多聚化之前和沟槽形成过程中是基于肌动球蛋白依赖性的细胞骨架重排，介导的肌球蛋白II电机与GP RNP。我们假设，重排导致这个过程的各个阶段，预聚集，沟招聘和远端压实，有一个共同的潜在的机械基础。我们将测试肌动球蛋白相互作用的模型，可能会导致GP RNP多聚化之前和期间的犁沟启动（目标1）和犁沟成熟（目标2）。我们进一步假设这些潜在的机制被不同地修改以产生不同的细胞输出。在目的1中，我们将测试的假设，在沟的起始，一个GP RNP相关的f-肌动蛋白网络被向外生长的星形微管，这是一个过程，耦合到全球激活GP RNP相关的肌球蛋白II修改。在目标2中，我们将测试的假设，在沟成熟，慢钙波与胞质分裂赋予肌球蛋白II活性和/或细胞骨架动力学，导致GP RNP压实在沟的远端的中间到远端的偏见。我们的研究结果将为细胞命运决定因素的分离提供新的基本机制。最近的研究表明，生殖系基因和多能性和致瘤性之间的联系，了解种质分离的机制将提供适用于生殖，再生和癌症生物学的知识。

DESCRIPTION (provided by applicant): Maternal inheritance of germ plasm ribonucleoparticles (GP RNPs) results in the activation of a conserved gene expression program for primordial germ cell specification, and we use the zebrafish as a vertebrate model system to study this process. Zebrafish maternally inherited GP RNPs have co-opted the cytoskeletal machinery to reach progressive levels of multimerization: aggregation prior to furrow initiation (pre- aggregation), recruitment to the furrow during its initiation, and distal compaction along th furrow undergoing maturation. These sequential processes result in the formation of four large masses of aggregated GP RNPs, which will eventually confer germ cell specification. The overarching hypothesis of this proposal is that increases in GP RNP multimerization prior to and during furrow formation are based on actomyosin-dependent rearrangements of the cytoskeleton, mediated by myosin II motors associated with GP RNPs. We hypothesize that rearrangements leading to various stages of this process, pre-aggregation, furrow recruitment and distal compaction, have a common underlying mechanistic basis. We will test models of actomyosin interactions that may result in GP RNP multimerization prior to and during furrow initiation (Aim 1) and during furrow maturation (Aim 2). We further hypothesize that these underlying mechanisms are modified differently to produce different cellular outputs. In Aim 1, we will test the hypothesis that, prior to and during furrow initiation, a GP RNP- associated f-actin network is modified by outwardly growing astral microtubules, a process that is coupled to the global activation of GP RNP-associated myosin II. In Aim 2, we will test the hypothesis that, during furrow maturation, slow calcium waves associated with cytokinesis confer a medial-to-distal bias of myosin II activity and/or cytoskeletal dynamics that result in GP RNP compaction at distal ends of the furrow. Our findings will provide insights into novel fundamental mechanisms for the segregation of cell fate determinants. Recent studies have shown a link between germ line genes and pluripotency and tumorigenicity, and understanding mechanisms of germ plasm segregation will provide knowledge applicable to reproductive, regenerative and cancer biology.