Signals in a Rapid Differentiation

快速分化的信号

• 批准号: 9307759
• 负责人: Chandler Fulton
• 金额: $ 9.5万
• 依托单位: Brandeis University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 1995-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9307759&HistoricalAwards=false
• 关键词: Signals; Rapid; Differentiation

9307759 Fulton The ultimate goal of this laboratory is to elucidate the orchestration of causal pathways during cell differentiation. The paradigm employed for this purpose is the 100-minute change of Naegleria gruberi from amoebae to flagellates--from one eukaryotic motility form to another--a differentiation that is exceptionally accessible for analysis except for lack of molecular genetics. The quest continues via three ongoing studies, each of interest separately but all converging toward the goal. 1) Surprisingly this quick change has two "checkpoints," at 10 min and at 20 min, at which the strength of some signal(s) is evaluated and decisions are made whether to progress toward differentiation or to "hold." Experiments are planned to define these checkpoints. 2) Certain conserved proteins are synthesized during differentiation in processes that involve signals regulating gene expression, mRNA stability, and localization of these proteins in flagella and associated organelles. These proteins include four calcium-binding proteins: a flagellar and a cell-body calmodulin, calcineurin B and centrin (a.k.a. caltractin), which becomes associated primarily with the basal bodies when these organelles form de novo during differentiation. Studies are continuing to define these calcium- binding proteins by examining gene expression, sequence, and protein localization. 3) The essential tool of DNA-mediated transformation of Naegleria is being developed using an homologous selectable marker, the OMP decarboxylase gene. The description of checkpoints and the study of conserved localized proteins is expected to yield results of immediate interest while the molecular genetic system is achieved. Once gene introduction is possible in Naegleria, the information from the first two aims will make it feasible to determine causal pathways for signals from initiation of differentiation to assembly of components into basal bodies and flagellae. %%% This research takes advantage of a unicellular organism, Naegleria gruberi, to study the principles involved in cellular differentiation. In response to chemical, mechanical, or physical changes in its environment, this organism, within one hundred minutes, can change from an ameba to an actively swimming, streamlined form with two flagellae. These two forms move by two very different mechanisms which involve very different sets of cellular machinery . This quick change represents an excellent model to study the biochemical signal pathways and changes in gene expression involved in a well-defined developmental process. The results should shed light on the mechanisms of cellular differentiation common to all living things, and will also expand our knowledge of the diversity of mechanisms by which a variety of organisms respond to environmental signals. ***

9307759富尔顿这个实验室的最终目标是阐明细胞分化过程中因果通路的协调。为了达到这个目的，所采用的模式是从变形虫到鞭毛虫的100分钟变化--从一种真核生物的运动形式到另一种--这种分化是非常容易分析的，除非缺乏分子遗传学。这项探索通过三项正在进行的研究继续进行，每项研究都单独感兴趣，但都朝着目标收敛。1)令人惊讶的是，这种快速变化有两个“检查点”，分别为10分钟和20分钟，在这两个“检查点”上，评估某个信号(S)的强度，并决定是走向差异化还是“保持”。计划进行实验来定义这些检查点。2)某些保守的蛋白质是在分化过程中合成的，包括调控基因表达的信号、mRNA的稳定性以及这些蛋白质在鞭毛和相关细胞器中的定位。这些蛋白质包括四种钙结合蛋白：鞭毛和细胞体钙调蛋白、钙调神经磷酸酶B和中心素(又名。钙调蛋白)，当这些细胞器在分化过程中从头形成时，它主要与基底联系在一起。研究继续通过检测基因表达、序列和蛋白质定位来确定这些钙结合蛋白。3)利用同源的可选择标记OMP脱羧酶基因正在开发利用DNA介导的Naegleria转化的必要工具。对检查点的描述和对保守的定位蛋白的研究有望在实现分子遗传系统的同时产生直接感兴趣的结果。一旦基因导入Naegleria成为可能，来自前两个目的的信息将使确定从分化开始到成分组装成基体和鞭毛的信号的因果路径是可行的。这项研究利用单细胞生物体--格氏Naegleria gruberi，来研究细胞分化的原理。对环境中的化学、机械或物理变化作出反应，这种有机体可以在100分钟内从阿米巴变成一种活跃游泳的流线型，有两个鞭毛。这两种形式通过两种非常不同的机制运动，涉及非常不同的细胞机制。这一快速变化是研究明确发育过程中涉及的生化信号通路和基因表达变化的极好模型。这些结果应该有助于揭示所有生物普遍存在的细胞分化机制，并将扩大我们对各种有机体对环境信号做出反应的机制的多样性的了解。***