Regulation of short-lived myeloid cells by the novel long non-coding RNA Morrbid

项目总结 中性粒细胞、嗜酸性粒细胞和炎性单核细胞合计占血白细胞的70%左右。 是人体内寿命最短的细胞之一。对这些髓系细胞寿命的精确调控是 对于保持有效的宿主对病原体的反应，同时将有害后果降至最低 长期发炎。然而，这些细胞的寿命如何受到严格控制，在很大程度上仍然存在 未知。这一提议的重点是我们最近发现的一种新型的长非编码RNA(LncRNA)，它作用于 作为分子“计时器”来控制这些炎性细胞的寿命。在我最近成立的 实验室，我们使用高通量测序和一种新的生物信息学工作流程来鉴定Morrbid，一种 以前未知的lncRNA是由促生存细胞因子有效和特异地诱导的 中性粒细胞、嗜酸性粒细胞和“炎性”单核细胞。我们的初步数据显示莫尔比特的消融 小鼠导致这些细胞在稳定状态下的频率显著降低 它们的生存能力存在缺陷。我们发现Morrid通过抑制转录来控制细胞存活 其邻近的促凋亡基因Bcl211(Bim)以等位基因特异性的方式表达。此外，我们还展示了 MorrBid在人类中是保守的，在人类短暂的髓系细胞中高度表达，在其 表达水平与高嗜酸性粒细胞(HE)病理有关。因此，定义分子 Morrid控制短寿命髓系细胞寿命的机制以及这种新的lncRNA在 炎症反应可能会揭示新的治疗靶点。因为已知lncRNAs靶向染色质 修饰邻近基因的复合体以调节其表达，并由Pro-Bid有效地诱导MorrBid 生存细胞因子，我们的中心假设是Morrid整合了支持生存的细胞外信号 通过染色质修饰途径控制Bcl2L11的表达，从而控制短暂的髓系细胞 生死存亡。该项目的目标1将定义Morrid抑制Bcl2L11的分子机制 表达对支持生存的细胞因子的反应。在目标2中，我们将确立莫尔比德在控制 炎症反应的大小。为此，我们将首先使用不同水平的小鼠品系 目的：确定该lncRNA如何控制嗜酸性粒细胞介导的肺过敏的发生和消退。 发炎。然后，我们将把这些研究翻译到人类身上，因为我们的初步数据显示，患有 高嗜酸性粒细胞(HE)病理的MORRBID水平急剧升高。我们将使用体外嗜酸性粒细胞 培养系统和人源化小鼠模型以确定MORRBID是否控制人类嗜酸性粒细胞 生死存亡。此外，使用HE患者的嗜酸性粒细胞，我们将确定MORRBID水平是否增加 导致高嗜酸性粒细胞增多症。总的来说，这些研究将勾勒出一种新的机制 在小鼠中，lncRNA通过细胞外信号决定短寿命髓系细胞的寿命 和人类。最终，我们希望利用这些调控机制的力量来实现治疗效益。

PROJECT SUMMARY Neutrophils, eosinophils and “inflammatory” monocytes collectively account for ~70% of blood leukocytes and are among the shortest-lived cells in the body. Precise regulation of the lifespan of these myeloid cells is critical to maintain effective host responses to pathogens while minimizing the deleterious consequences of prolonged inflammation. However, how the lifespan of these cells is strictly controlled remains largely unknown. This proposal is focused on a novel long non-coding RNA (lncRNA) we recently discovered that acts as a molecular `timer' to control the duration of the lifespan of these inflammatory cells. In my recently established laboratory, we used high-throughput sequencing and a novel bioinformatic workflow to identify Morrbid, a previously uncharacterized lncRNA that is potently and specifically induced by pro-survival cytokines in neutrophils, eosinophils and “inflammatory” monocytes. Our preliminary data shows that ablation of Morrbid in mice leads to a dramatic reduction in the frequency of these cells at steady state as a result of significant defects in their survival capacity. We found that Morrbid controls cell survival by repressing the transcription of its neighboring pro-apoptotic gene, Bcl2l11 (Bim), in an allelic-specific manner. In addition, we show that Morrbid is conserved in humans, highly expressed in human short-lived myeloid cells and alterations in its levels of expression are associated with hypereosinophilic (HE) pathologies. Thus, defining the molecular mechanisms by which Morrbid controls short-lived myeloid cell lifespan and the role of this novel lncRNA during inflammatory responses will likely reveal new therapeutic targets. As lncRNAs are known to target chromatin modifying complexes to neighboring genes to regulate their expression and Morrbid is potently induced by pro- survival cytokines, our central hypothesis is that Morrbid integrates pro-survival extracellular signals with chromatin modification pathways to control Bcl2l11 expression and thus short-lived myeloid cell survival. Aim 1 of this project will define the molecular mechanism by which Morrbid represses Bcl2l11 expression in response to pro-survival cytokines. In aim 2, we will establish the role of Morrbid in controlling the magnitude of inflammatory responses. For this purpose, we will first use mouse strains with different levels of Morrbid to determine how this lncRNA controls the onset and resolution of eosinophil-mediated lung allergic inflammation. We will then translate these studies to humans as our preliminary data shows that patients with hypereosinophic (HE) pathologies have drastically elevated levels of MORRBID. We will use ex vivo eosinophil culture systems and a humanized mouse model to establish whether MORRBID controls human eosinophil survival. Moreover, using eosinophils from HE patients we will define whether increased MORRBID levels contribute to the development of hypereosinophilia. Collectively, these studies will delineate a novel mechanism by which a lncRNA determines the lifespan of short-lived myeloid cells in response to extracellular cues in mouse and humans. Ultimately, we hope to harness the power of these regulatory mechanisms for therapeutic benefit.