Architecture of endolysosomal pathways in tetrahymena

该项目将解决有关细胞结构和功能之间关系的演变的基本问题。 所有的细胞都有一套共同的活动，其中许多活动涉及与环境的相互作用。 这项提议的主题是允许细胞从环境中吸收颗粒的途径，这些颗粒可以被带到一个被消化的隔间。 或者，这种摄入的颗粒可以被转运到其他区室并整合到细胞代谢中。 这项研究将确定不同的细胞是否依赖于相同的机制，或者随着时间的推移，是否已经进化出不同的机制来完成类似的任务。该研究还将通过实施实验来解决细胞如何控制摄入颗粒的运输，这些实验测试了各种可能的结果相互竞争的假设，并且细胞可以精确地调节不同途径的“流动”。 该项目将在纤毛虫四膜虫嗜热菌中进行，并将重点放在“内溶酶体”网络中的途径上。 四膜虫通过吞噬依赖性途径摄取细菌，然后将这些细菌置于吞噬溶酶体中，其活性取决于水解酶的递送。这项研究将确定蛋白质递送到吞噬溶酶体的途径，并询问它们与哺乳动物细胞中使用的途径是否相同或不同。在四膜虫中，水解酶也被递送以产生特定的分泌隔室。 该项目中的实验将测试这一假设，即CORVET家族中分子束缚复合物之间的竞争决定了关键水解酶对分泌细胞器与吞噬溶酶体的相对通量，这取决于细胞条件。实验将基于特定CORVET亚基丰度的自然和诱导波动。 实验还将利用CORVET系链被Rab GTP酶募集的事实，使得Rab活性的操纵可用于间接影响CORVET功能。 该项目将提供一个环境，介绍本科生的研究，并为一名博士生和一名博士后研究员的培训。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

The project will address fundamental questions about the evolution of the relationship between structure and function in cells. All cells share a set of activities, many of which involve interactions with their environment. The subject of this proposal is the pathways that allow cells to take up particles from their environment, which can be carried to a compartment where they are digested. Alternatively, such ingested particles can be transported to other compartments and integrated into cellular metabolism. The research will determine if different cells are relying on the same mechanisms, or whether, over time, have evolved diverse mechanisms to achieve similar tasks. The research will also address how cells control the transport of ingested particles by implementing experiments which test the hypothesis that the various possible outcomes are in competition with one another, and that a cell can precisely regulate the “flow” down different pathways. The project will be pursued in the ciliate Tetrahymena thermophila and will focus on pathways in the ‘endolysosomal’ network. Tetrahymena ingests bacteria by a phagocytosis-dependent pathway, and then digests those bacteria in phagolysosomes whose activity depends on delivery of hydrolytic enzymes. The research will define the pathways involved in delivery of proteins to phagolysosomes and ask whether they are the same or different as the pathways used in mammalian cells. In Tetrahymena, hydrolytic enzymes are also delivered to generate a specific secretory compartment. Experiments in the project will test the hypothesis that competition between molecular tethering complexes in the CORVET family determines the relative flux of key hydrolytic enzymes to secretory organelles vs phagolysosomes, depending on cellular conditions. The experiments will be based on natural and induced fluctuations in the abundance of specific CORVET subunits. The experiments will also take advantage of the fact that CORVET tethers are recruited by Rab GTPases, so that manipulation of Rab activities can be used to indirectly influence CORVET function. The project will provide an environment to introduce undergraduates to research, and for the training of one PhD student and one postdoctoral fellow.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.