Integrin-Based Mechanisms in Terminal Erythroid Maturation

描述（由申请人提供）： 在红细胞生成过程中，成熟的成红细胞与细胞外基质成分和其他骨髓细胞在其局部微环境中形成粘附相互作用。众所周知，成红细胞群依赖于这种相互作用来实现最佳的细胞成熟，但红细胞生成微环境在支持和调节红细胞成熟中的确切作用尚不清楚。细胞膜上的整合素是成红细胞与细胞以及细胞与基质相互作用的关键介质。除了促进粘附相互作用之外，整联蛋白介导成红细胞的细胞外和细胞内环境之间的双向信号传导（由外向内和由内向外）。整合素也是细胞骨架重组的重要介质，细胞骨架重组是红系成熟终末阶段发生的结构变化的核心过程。在这里，我们建议测量主要的成红细胞整合素的膜动力学，定义整合素介导的成红细胞粘附相互作用的分子调控，并表征整合素动力学和细胞骨架重组之间的联系。我们还将研究整合素驱动的信号传导和促红细胞生成素驱动的信号传导之间的关系，它们可以共同作用以优化稳态和/或应激条件下的红细胞生成。我们的最终目标是了解整合素依赖性功能对红细胞生成的影响。我们的实验室非常适合开展这些工作，我们拥有多种先进的定量单分子和单细胞成像技术以及流式细胞术和小鼠模型方面的专业知识。基于我们的初步数据，我们假设成红细胞整合素动力学和信号传导均调节红细胞成熟并受其支配，并且在此过程中整合素介导的事件与促红细胞生成素介导的信号传导相互作用。在目标1中，我们将描述 整合素在成熟成红细胞上的膜动力学，定义了这种动力学如何被配体接合和细胞骨架重组控制，并阐明了这些动力学对细胞内信号传导途径的调节。在目标2中，我们将描述红细胞生成素依赖性途径和整合素依赖性途径之间潜在相互作用的机制，这些途径调节终末红细胞成熟。该项目的成功完成将为红细胞发育的机制提供新的见解，并可能有助于确定红细胞生成障碍治疗干预的新靶点。 (End摘要）

DESCRIPTION (provided by applicant): During erythropoiesis, maturing erythroblasts form adhesive interactions with extracellular matrix components and with other bone marrow cells in their local microenvironment. It is known that clusters of erythroblasts rely on such interactions for optimal cell maturation, but the precie role of the erythropoietic microenvironment in supporting and modulating erythroid maturation is unclear. Integrins in the cell membrane are the key mediators of erythroblast cell-cell and cell-matrix interactions. In addition to promoting adhesion interactions, integrins mediate bidirectional signaling (outside-in and inside-out) between the extracellular and intracellular environments of the erythroblast. Integrins are also important mediators of cytoskeletal reorganization, a process that is central to the structural changes occurring in the terminal stages of erythroid maturation. Here, we propose to measure the membrane dynamics of the major erythroblast integrins, define the molecular regulation of integrin-mediated erythroblast adhesion interactions, and characterize the links between integrin dynamics and cytoskeletal reorganization. We will also investigate the relationship between integrin-driven signaling and erythropoietin-driven signaling, which could work together to optimize erythropoiesis under homeostatic and/or stress conditions. Our ultimate goal is to understand the impact of integrin-dependent functions on erythropoiesis. Our laboratory is ideally suited to undertake these endeavors, having at our disposal multiple advanced, quantitative single-molecule and single-cell imaging techniques as well as expertise in multicolor flow cytometry and mouse models. Based on our preliminary data, we hypothesize that erythroblast integrin dynamics and signaling both modulate and are governed by erythroid maturation and that integrin-mediated events interact with erythropoietin-directed signaling in this process. In Aim 1, we will characterize the membrane dynamics of integrins on the maturing erythroblast, define how such dynamics are controlled by ligand engagement and cytoskeletal reorganization, and elucidate the regulation of intracellular signaling pathways by these dynamics. In Aim 2, we will characterize mechanisms of potential interaction between erythropoietin-dependent pathways and integrin-dependent pathways that regulate terminal erythroid maturation. Successful completion of this project will provide new insights into the mechanisms underlying erythroid development and may aid in the identification of novel targets for therapeutic intervention in disorders of erythropoiesis. (End of Abstract)