Translational regulation of tissue resident macrophages by GCN2

摘要 信使核糖核酸的翻译，或蛋白质的合成，是一种基本的细胞过程，可以在几种情况下失调。 人类疾病。巨噬细胞是一种异质群体，存在于大多数组织中，并采用 组织特有的功能。MRNA翻译调控在巨噬细胞及其组织中的作用 具体的功能还不是很清楚。拟议研究的广泛目标是了解如何 在应激过程中，mRNA翻译的失调控制着组织驻留巨噬细胞的功能。具体的 这项研究的目标是确定GCN2(一般控制不可降压2)依赖的翻译 巨噬细胞的控制影响巨噬细胞在红细胞产生和清除中的功能，并揭示 调节这一效应的基因。GCN2是一种丝氨酸/苏氨酸蛋白激酶，属于信号网络 通过翻译调节因子eIF2(真核翻译)协调细胞对营养胁迫的反应 启动因子2)。GCN2感知氨基酸水平并磷酸化eIF2以响应氨基酸 缺乏症。P-eIF2抑制全局信使核糖核酸的翻译，但却矛盾地刺激了 关键的应激反应基因，如ATF4(激活转录因子4)。应激反应的上调 响应GCN2/eIF2信号的基因激活转录程序，帮助细胞克服 在不利的条件下或发生细胞凋亡。GCN2功能之前已链接到重要 生理和病理条件，如记忆力形成、癌症和炎症性疾病。 然而，GCN2在调节组织驻留巨噬细胞中的作用及其在红细胞产生中的功能 而且清除的特征还没有确定。我们目前的模型表明GCN2控制RBC的产生 并通过调节巨噬细胞中的mRNA翻译来清除应激。因此，我们建议 以下是我们实现目标的目标：首先，我们将确定GCN2在红细胞清除中的重要性 巨噬细胞(目标1)，并确定GCN2影响这一过程的分子机制。接下来，我们 将阐明GCN2如何控制巨噬细胞的红细胞成熟和产生(目标2)。最后，我们会 研究巨噬细胞如何通过GCN2感知机械力(目标3)。为了实现这些目标，我们将 在巨噬细胞中使用缺乏GCN2或携带抗磷eIF2的转基因小鼠及其研究现状 在全基因组水平上研究信使核糖核酸翻译的技术。我们的小鼠模型以及体内和体外 实验将严格评估巨噬细胞在依赖GCN2的发展中的中心作用 压力过程中的缺陷。我们的全基因组方法和对选定靶点的体外功能分析将 发现GCN2下游在巨噬细胞中发挥重要作用的新的翻译调控基因 应激过程中红细胞生成的调节。

SUMMARY mRNA translation, or protein synthesis, is a fundamental cellular process that can be dysregulated in several human diseases. Macrophages are heterogeneous populations that are present in most tissues and adopt tissue specific functions. The role of mRNA translational control in macrophages and in regards to their tissue specific functions is not well understood. The broad goal of the proposed studies is to understand how dysregulation of mRNA translation controls tissue-resident macrophage function during stress. The specific goals of this study are to identify how GCN2 (general control nonderepressible 2)-dependent translational control in macrophages affects macrophage function in RBC production and clearance and to uncover the genes mediating this effect. The GCN2 is a serine/threonine-protein kinase that belongs to a signaling network that coordinates cellular response to nutrient stress through translational regulator eIF2 (Eukaryotic translation initiation factor 2). GCN2 senses amino acid levels and phosphorylates eIF2 in response to amino acid deficiency. p-eIF2 inhibits global mRNA translation but paradoxically stimulates the translation of a subset of key stress-response genes such as ATF4 (Activating Transcription Factor 4). Upregulation of stress-response genes in response to GCN2/eIF2 signaling activates a transcription program that helps the cells to overcome unfavorable conditions or undergo apoptosis. GCN2 function has been previously linked to important physiological and pathological conditions such as memory formation, cancer and inflammatory diseases. However, the role of GCN2 in regulating tissue-resident macrophages and their functions in RBC production and clearance has not been characterized. Our current model suggests that GCN2 controls RBC production and clearance during stress through regulation of mRNA translation in macrophages. Therefore, we propose the following aims to achieve our goals: First we will determine the importance of GCN2 in RBC clearance by macrophages (Aim 1) and define molecular mechanisms through which GCN2 impact this process. Next, we will elucidate how GCN2 controls RBC maturation and production by macrophages (Aim 2). Finally, we will examine how mechanical force sense by macrophage through GCN2 (Aim 3). To achieve these goals we will use transgenic mice lacking GCN2 or carrying phospho-resistant eIF2 in macrophages and state-of-art technology to study mRNA translation at genome-wide level. Our mouse models and in vivo and in vitro experiments will rigorously assess the central role of macrophages in development of GCN2-dependent defects during stress. Our genome-wide approach and in vitro functional analysis of selected targets will discover novel translationally regulated genes downstream of GCN2 that play important roles in macrophage regulation of RBC production during stress.