Regulation of hematopoiesis by ribosomal protein paralogs

项目摘要/摘要 核糖体蛋白(RP)在发育和疾病中起着重要的调节作用； 然而，他们如何做到这一点仍不清楚。RP作用的潜在模式可分为两类：对 核糖体本身或核糖体外的功能，但在物理上与核糖体分离。 处理RP功能的传统功能丧失方法不能区分这些动作模式，因为 大多数RP是核糖体生物发生和/或功能所必需的，因此这种RP基因的消融会减弱 两种行动模式。因此，明确地确定了腮腺体外RP的贡献 生物过程的功能仍然是知识中的一个严重差距。重要的是，我们已经确定了一名RP， RPL22不是核糖体生物发生或功能所必需的，但仍发挥着关键的、选择性的作用 在造血方面。RPL22不仅调节胚胎中造血干细胞(HSC)的出现，而且还 调节成人的HSC功能，以及包括B和T淋巴细胞在内的更远端的造血阶段 发展。在特定的造血过程中对RPL22的选择性要求的基础仍然存在 不清楚；然而，我们最近确定Rp22调节胎儿HSC出现的能力是 依赖于它与hnRNP-A1的物理结合，hnRNP-A1可以调节翻译。此外，hnRNP-A1 选择性地与物理上与核糖体分离的Rpl22分子结合。因此，我们 有一个史无前例的机会来研究Rpl22的体外功能在 造血术。我们推测，Rpl22主要通过其体外活动调节造血， 通过与hnRNP-A1结合，调节RNA靶标的翻译、剪接和可能的稳定性 这取决于蜂窝环境的不同。事实上，当Rp22通过调控胎儿HSC的出现时 Smad1、Rpl22的表达通过调节脂氧合酶的表达来控制成年HSC的行为 (Alox12)，它产生激活PPARd的类脂物种，PPARd是脂肪酸氧化的主要调节因子(FAO)。AS FAO已被证明调节HSC的自我更新，我们假设Rpl22调节Alox12信号转导 维护HSC。在这项提案中，我们将在两个目标上检验这些假设。目标1试图确定 Rpl22/hnRNP-A1轴在HSC生物学调控中发挥作用，并识别Rpl22调控的特异性 依赖于Rp22与hnRNP-A1相关的胎儿和成人的造血过程。AIM2专注于 研究下游Alox12驱动的FAO途径的机制和作用，Rpl22通过这些途径进行控制 成人HSC功能。在追求这些研究的过程中，我们将把尖端的结构分析与独特的 斑马鱼和各种新型小鼠模型的优势，并验证在人类祖先身上的核心发现。 综上所述，这些研究将为人们首次深入了解这种新的、非同体的“兼职”功能。 Rp通过其调控生物学过程，可能揭示Rpl22的组织特异性基础。 通过特定的造血过程表现出的依赖性。

PROJECT SUMMARY/ABSTRACT Ribosomal proteins (RP) are increasingly understood to play crucial regulatory roles in development and disease; however, the way they do so remains unclear. The potential modes of RP action fall into two classes: effects on the ribosome itself or extraribosomal functions carried out while physically separate from the ribosome. Traditional loss-of-function approaches to address RP function fail to distinguish these modes of action because most RP are essential for ribosome biogenesis and/or function and so ablation of such RP genes attenuates both modes of action. Consequently, an unequivocal determination of the contributions of extraribosomal RP functions to biological processes remains a critical gap in knowledge. Importantly, we have identified an RP, Rpl22, which is not required for ribosome biogenesis or function, but nevertheless plays critical, selective roles in hematopoiesis. Rpl22 not only regulates hematopoietic stem cell (HSC) emergence in the embryo but also regulates adult HSC function, as well as more distal stages of hematopoiesis including B and T lymphocyte development. The basis for the selective requirement for Rpl22 in particular hematopoietic processes remains unclear; however, we have recently determined that the capacity of Rpl22 to regulate fetal HSC emergence is dependent upon its physical association with hnRNP-A1, which can regulate translation. Moreover, hnRNP-A1 selectively associates with Rpl22 molecules that are physically separate from the ribosome. Consequently, we have an unprecedented opportunity to investigate the importance of the extraribosomal function of Rpl22 in hematopoiesis. We hypothesize that Rpl22 regulates hematopoiesis chiefly through its extraribosomal activity, by associating with hnRNP-A1, and regulating the translation, splicing and possibly the stability of RNA targets that differ depending on the cellular context. Indeed, while Rpl22 controls fetal HSC emergence by regulating the expression of Smad1, Rpl22 controls adult HSC behavior by regulating the expression of a lipoxygenase (Alox12), which generates lipid species that activate PPARd, a master regulator of fatty acid oxidation (FAO). As FAO has been shown to regulate HSC self-renewal, we hypothesize that Rpl22 regulates Alox12 signaling to maintain HSCs. In this proposal, we will test these hypotheses in two aims. Aim 1 seeks to determine how the Rpl22/hnRNP-A1 axis exerts its functions in controlling HSC biology, and identify the specific Rpl22-regulated fetal and adult hematopoietic processes that depend on Rpl22 association with hnRNP-A1. Aim2 focuses on investigating the mechanism and role of downstream Alox12-driven FAO pathways through which Rpl22 controls adult HSC function. In pursing these studies, we will integrate cutting edge structural analysis with the unique strengths of zebrafish and a variety of novel mouse models, and verify core findings in human progenitors. Together, these studies will provide the first insight into the novel, extraribosomal “moonlighting” functions through which RP regulate biological processes, and may reveal the basis for the tissue specificity of Rpl22- dependence displayed by particular hematopoietic processes.