Context dependent amino acid availability and sensing determines humoral immunity

项目摘要 氨基酸是至关重要的营养素，对增强免疫力也很重要。然而，我们已经限制了 了解免疫挑战如何调节氨基酸的可利用性，以及免疫细胞如何 感知氨基酸并传递信号以执行免疫反应。RAG-GTP酶最近被 被认为是一种关键的氨基酸传感器，主要将氨基酸信号传递到机械靶标 非造血细胞中的雷帕霉素(MTOR)复合体1(MTORC1)。然而，Rag-GTP酶也调节 转录因子TFEB，HLH-亮氨酸拉链小眼症(MIT/TFE)家族成员 转录因子，其在B细胞中的功能尚不清楚。此外，Rag-GTPase不依赖于 已经确定了mTORC1的激活。Rag-GTPase和mTORC1如何协同调节体液 豁免权尚未得到解决。我们比较了RAG-GTP酶和mTORC1在B细胞中的功能 利用基因敲除模型进行体内反应。我们的数据显示，虽然Rag-GTPase和mTORC1 是全身免疫挑战所必需的，Rag-GTP酶而不是mTORC1对体液免疫至关重要 对呼吸道流感感染的反应。Rag-GTPase和Rag-GTPase之间的这种不同要求 MTORC1与系统免疫和呼吸道之间氨基酸利用率的差异有关 流感感染。此外，我们还发现Rag-GTP酶抑制TFEB并促进自噬， 它与ERK激活有关，但在很大程度上不依赖于mTORC1。因此，我们假设 呼吸道病毒感染时特定氨基酸的可获得性降低使B细胞依赖RAG-1。 GTPase-TFEB途径，用于GC反应和抗流感抗体的产生。在目标1中，我们将首先测试 活病毒免疫攻击的呼吸道途径是否为RAG-GTP酶的决定因素 依赖，但不依赖于mTORC1，体液免疫。第二，我们将进一步调查时间和 免疫挑战期间氨基酸可利用性的空间动态。最后，我们将测试饮食是否 氨基酸干预可提高机体对呼吸道病毒感染的体液免疫能力。在目标2中，我们将 利用互补的功能损失和功能增益方法来阐明下游信令 RAG-GTP酶促进GC反应和体液免疫的机制。我们将进一步描述 用无偏倚蛋白质组学方法研究B细胞中Rag-GTP酶的相互作用。我们的研究将定义一部小说 RAG-GTPase-ERK-TFEB信号轴响应氨基酸可用来促进B细胞激活和 产生对抗呼吸道病毒感染的抗体。

Project Summary Amino acids are crucial nutrients that are also important to support immunity. Yet, we have limited understanding with regard to how immune challenges modulate amino acid availability, and how immune cells sense amino acid and transduce the signals to execute immune reponses. Rag-GTPase has recently been identified as a key amino acid sensor that mostly transduce signals from amino acids to mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) in non-hematopoietic cells. However, Rag-GTPase also modulates transcription factor TFEB, a member of the microphthalmia (MiT/TFE) family of HLH-leucine zipper transcription factors, whose functions in B cells remain unknown. Moreover, Rag-GTPase independent mTORC1 activation has been identified. How Rag-GTPase and mTORC1 coordinates to regulate humoral immunity has not been addressed. We compared the functions of Rag-GTPase and mTORC1 in B cell response in vivo using genetic knockout models. Our data showed that while both Rag-GTPase and mTORC1 are required for systemic immune challenges, Rag-GTPase, but not mTORC1, is critical for humoral immune response towards respiratory influenza infection. This divergent requirement between Rag-GTPase and mTORC1 is associated with differential amino acid availability between systemic immunization and airway influenza infection. Furthermore, we showed that Rag-GTPase suppresses TFEB and promotes autophagy, which is associated with ERK activation, but largely independent of mTORC1. Thus, we hypothesize that reduced availability of specific amino acids during respiratory viral infection renders B cells dependent on Rag- GTPase-TFEB pathway, for GC reaction and anti-influenza antibody production. In Aim 1, we will first test whether the respiratory route of live virus immune challenge is the determining factor for Rag-GTPase dependent, but mTORC1 independent, humoral immunity. Second, we will further investigate the temporal and spatial dynamics of amino acid availability during immune challenges. Finally, we will test whether dietary amino acid intervention can improve humoral immunity against respiratory viral infection. In Aim 2, we will utilize complementary loss-of-function and gain-of-function approaches to elucidate the downstream signaling mechanisms by which Rag-GTPase promotes GC reaction and humoral immunity. We will further characterize the Rag-GTPase interactome in B cells using unbiased proteomics approach. Our study will define a novel Rag-GTPase-ERK-TFEB signaling axis that respond to amino acid availability to promote B cell activation and antibody production against airway viral infection.