The central role of the PACS family of proteins in cellular organization

背景许多蛋白质在细胞内的运动是由膜运输机制保证的。这一机制使蛋白质能够正确的亚细胞定位，从而确保蛋白质履行其细胞功能。总体而言，膜转运维持了细胞内环境的稳定。该建议以膜转运调节蛋白磷酸尿酸簇排序(PACS)1和2为中心。PACS蛋白与多个细胞蛋白形成关键相互作用，称为Cargo，并将后者运送到正确的亚细胞位置。PACS-1和PACS-2贩运事件的重要性和多样性表明了这些蛋白质在贩运中发挥的核心作用。事实上，PACS-1的运输与初级纤毛的形成、将激活分子输送到特定的细胞隔间以及将非活性前体蛋白转化为活性蛋白等功能有关。相反，PACS-2转运事件可以在关键的细胞事件中发挥作用，如维持细胞钙水平和调节细胞死亡途径。假设我们假设PACS蛋白是细胞的中心组织者，通过协调多个蛋白质-蛋白质相互作用，使巡回货物能够运输到精确的亚细胞位置。蛋白质的适当运输对它们随后履行其功能至关重要。我们进一步假设，定义新的PACS：蛋白质相互作用的功能将为定义PACS蛋白质在细胞组织中的中心作用提供重要的见解。进展我的实验室发现了一条由PACS-1控制的新的转运途径。这一途径涉及将激素输送到特定的亚细胞位置，即致密的核心分泌颗粒。此外，我的实验室已经定义了PACS-1和PACS-2相互作用的全部伙伴范围，这揭示了PACS在细胞核中出人意料的集中作用。总体而言，我们将研究这些机制，并借助我们在上一次筹资期间完善和发展的各种技术。目的阐明PACS-1和PACS-2在多种膜转运途径中的作用是本研究的主要目的。目的：明确PACS-1在货物分选致密核心分泌颗粒中的作用。目的2：明确PACS-1在致密的核心分泌颗粒分泌货物中的作用。目的3：明确PACS-1和PAC-2在核心意义上的蛋白质-蛋白质相互作用和作用，这一基于发现的研究计划将解决与中央膜转运调节因子PACS蛋白质有关的重要和独特的问题。我们的长期计划集中在探索我们在前一个资金期间发现的PACS-1和PACS-2货物的全系列。

Background The movement of many proteins within cells is ensured by the membrane trafficking machinery. This machinery enables the correct subcellular localization of proteins which guarantees proteins fulfill their cellular functions. Overall, membrane trafficking maintains cellular homeostasis. This proposal is centered on the membrane trafficking regulator proteins Phosphofurin Acid Cluster Sorting (PACS) 1 and 2. The PACS proteins form key interactions with multiple cellular proteins termed cargo and shuttle the latter cargo to the correct subcellular location. The importance and diversity of PACS-1 and PACS-2 trafficking events demonstrates the central role these proteins play in trafficking. Indeed, PACS-1 trafficking is implicated in the formation of primary cilia, the delivery of activating molecules to specific cellular compartments and the conversion of inactive precursor proteins to active proteins, amongst other functions. Conversely, PACS-2 trafficking events can function during key cellular events such as maintaining cellular calcium levels and modulating cellular death pathways. Hypothesis We hypothesize that PACS proteins are central organizers of the cell by orchestrating multiple protein-protein interactions to enable trafficking of itinerant cargo to precise subcellular locales. Proper trafficking of proteins is critical for them to subsequently perform their functions. We further hypothesize that defining how novel PACS:protein interactions function will shed significant insight into defining the central role of PACS proteins in cellular organization. Progress My laboratory has identified a novel trafficking pathway that is controlled by PACS-1. This pathway is implicated in the delivery of hormones to a specific subcellular location, the dense core secretory granule. In addition, my laboratory has defined the full range of PACS-1 & PACS-2 interacting partners which has revealed an unexpected concentration of PACS roles in the nucleus. Overall, we will study these mechanisms aided by a variety of techniques that we have perfected and developed during the previous funding period. Aims Elucidating the roles of PACS-1 & PACS-2 in multiple membrane trafficking pathways is the overarching aim of this research program. Aim1: Defining the role of PACS-1 in the sorting of cargo to dense core secretory granules. Aim 2: Defining the role of PACS-1 in the secretion of cargo from the dense core secretory granule. Aim 3: Defining the protein-protein interactions and roles of PACS-1 and PAC-2 in the nucleus Significance This discovery-based research program will address important and unique questions concerning the pathways that are governed by the central membrane trafficking regulator PACS proteins. Our long-term plans are centered on exploring the full range of PACS-1 and PACS-2 cargo that we have discovered during the previous funding period.