Evolution of the Contractile Vacuole

收缩液泡的进化

• 批准号: RGPIN-2014-05516
• 负责人: Dacks, Joel
• 金额: $ 3.86万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=611684
• 关键词: Evolution; Contractile; Vacuole

The organelles of the membrane-trafficking system underlie the movement of material within eukaryotic cell, as well as exchange with the extracellular environment. The effective action of this organellar system mediates healthy human cellular function, as well as that of plants of agricultural importance and algae of economic and environmental impact. Evolving such an organellar system would have been a crucial step in the transformative process establishing the eukaryotic cellular configuration and giving rise to nearly all of the biological diversity that we see today. My research program involves understanding the patterns and processes that drive the evolution of the membrane-trafficking organelles. This provides insights into the events and fundamental forces that have shaped our cellular history. The comparative nature of this work also yields important cell biological data identifying novel cellular components and commonalities between well-studied model eukaryotes and lesser characterized organisms. A critical step to understanding the cell biology of modern cells and how it evolved is establishing homology between organelles in diverse eukaryotes. The endoplasmic reticulum (ER), Golgi, and plasma membrane have obvious direct organellar orthologues and are deduced to have been present in the Last Common Ancestor of Eukaryotes (LECA). However, while molecular phylogenetic and cell biological data have demonstrated homology between the various organelles of the endocytic system (recycling endosome, late endosome, lysosome), the relationships between them are unresolved. In particular, endocytic organelles also have secretory counterparts and it is unclear from where these organelles have evolved. These include secretory granules, trichocysts, and contractile vacuoles. The contractile vacuole (CV) is an osmoregulatory organelle found in ecologically important and diverse freshwater and soil-dwelling organisms (eg. ciliates, dictyostelids). Nonetheless, CV cell biology is only now being assessed using modern methods. As the name implies, the CV is presumed to be a vacuole/lysosome homologue. This project will use molecular evolutionary and transcriptomic analysis to examine the evolution and function of the CV, specifically, whether it is derived from a single homologous ancestor or derived independently from endolysosomal organelles. Based on morphological similarities, the starting hypothesis is that CVs in diverse eukaryotes are derived from a single common ancestor predating LECA. This hypothesis will be addressed in three short-term goals. Firstly, comparative genomics of known CV proteins will be undertaken yielding a possible conserved core CV complement, as well as lineage-specific features. Secondly, transcriptomics of three tractable, taxonomically disparate, model eukaryotes will be used determine genes that are differentially expressed upon induction of CV function. This will not only validate whether the ‘core CV complement’ are actually involved in CV function in diverse eukaryotes, it may also identify novel genes of functional CV importance. Finally, phylogenetic analysis of protein families associated with CV function (eg. SNAREs, stomatins, aquaporins) will test the hypothesis of ancient CV monophyly or determine from which other organelles the CV might have arisen. By identifying the genes of importance in CV function and their distribution in eukaryotes, we gain information about the workings of an organelle present in ecologically crucial lineages of eukaryotes. By understanding the evolution of the CV, we will be able to integrate an important organelle into the larger framework of membrane-trafficking evolution and gain a better understanding into the rise of eukaryotic life on Earth.

膜运输系统的细胞器是真核细胞内物质运动以及与细胞外环境交换的基础。这种细胞器系统的有效作用介导健康的人类细胞功能，以及具有农业重要性的植物和具有经济和环境影响的藻类的功能。进化出这样一个细胞器系统将是建立真核细胞构型的变革过程中的关键一步，并产生了我们今天看到的几乎所有生物多样性。 我的研究计划包括了解驱动膜运输细胞器进化的模式和过程。这提供了对塑造我们细胞历史的事件和基本力量的见解。这项工作的比较性质也产生了重要的细胞生物学数据，确定新的细胞成分和共同点之间的充分研究的模型真核生物和较少的特征生物。 理解现代细胞的细胞生物学及其进化的关键一步是在不同真核生物的细胞器之间建立同源性。内质网（ER），高尔基体和质膜有明显的直接细胞器同源物，并推断已存在于真核生物的最后共同祖先（LECA）。然而，尽管分子系统发育和细胞生物学数据已经证明了内吞系统的各种细胞器（再循环内体、晚期内体、溶酶体）之间的同源性，但它们之间的关系尚未得到解决。 特别是，内吞细胞器也有分泌对应物，目前还不清楚这些细胞器从哪里进化而来。这些包括分泌颗粒、囊泡和收缩泡。收缩泡（CV）是在生态上重要和多样的淡水和土壤生活生物（例如，哺乳动物）中发现的一种重要的调节细胞器。纤毛虫、网柱虫）。尽管如此，CV细胞生物学现在才使用现代方法进行评估。顾名思义，CV被认为是液泡/溶酶体同源物。该项目将使用分子进化和转录组学分析来研究CV的进化和功能，特别是，它是否来自单一同源祖先或独立于内溶酶体细胞器。 基于形态学的相似性，最初的假设是不同真核生物中的CV来自于早于LECA的单一共同祖先。 这一假设将在三个短期目标中得到解决。首先，将进行已知CV蛋白的比较基因组学，产生可能的保守的核心CV补体以及谱系特异性特征。其次，将使用三种易处理的、分类学上不同的模型真核生物的转录组学来确定在诱导CV功能时差异表达的基因。这不仅将验证“核心CV补体”是否真的参与不同真核生物中的CV功能，还可以鉴定功能CV重要性的新基因。最后，与CV功能相关的蛋白质家族的系统发育分析（例如，SNARE、气孔蛋白、水通道蛋白）将检验古老CV单系性的假设或确定CV可能起源于哪些其他细胞器。 通过识别CV功能的重要基因及其在真核生物中的分布，我们获得了关于真核生物生态关键谱系中存在的细胞器的工作的信息。通过了解CV的进化，我们将能够将一个重要的细胞器整合到膜运输进化的更大框架中，并更好地了解地球上真核生命的兴起。