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

项目摘要 中性粒细胞、嗜酸性粒细胞和“炎性”单核细胞共同占血液白细胞的~70%， 是人体中寿命最短的细胞之一。精确调节这些骨髓细胞的寿命是 关键是保持有效的宿主对病原体的反应，同时最大限度地减少有害后果， 长期炎症然而，如何严格控制这些细胞的寿命在很大程度上仍然是一个问题。 未知这项提议的重点是我们最近发现的一种新的长非编码RNA（lncRNA）， 作为一种分子“计时器”来控制这些炎症细胞的寿命。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识别Morrbid，一种 以前未表征的lncRNA，其由促存活细胞因子有效且特异性地诱导， 嗜中性粒细胞、嗜酸性粒细胞和“炎性”单核细胞。我们的初步数据显示， 小鼠导致这些细胞在稳态下的频率急剧降低，这是由于显著的 生存能力的缺陷。我们发现Morrbid通过抑制以下转录来控制细胞存活： 其相邻的促凋亡基因Bcl 2l 11（Bim）以等位基因特异的方式。此外，我们表明， Morrbid在人类中是保守的，在人类短寿命髓样细胞中高度表达，并且其基因组的改变在人类中是保守的。 表达水平与嗜酸性粒细胞增多（HE）病理有关。因此，定义分子 Morrbid控制短寿命骨髓细胞寿命的机制以及这种新型lncRNA在 炎症反应将可能揭示新的治疗靶点。由于已知lncRNA靶向染色质 修饰邻近基因的复合物以调节它们的表达，而Morrbid是由前 我们的中心假设是Morrbid整合了促生存细胞外信号 通过染色质修饰途径控制Bcl 2l 11表达， 生存本项目的目标1将确定Morrbid抑制Bcl 2l 11的分子机制 响应于促存活细胞因子的表达。在目标2中，我们将确定Morrbid在控制 炎症反应的程度。为此，我们将首先使用具有不同水平的 目的是确定这种lncRNA如何控制嗜酸性粒细胞介导的肺过敏反应的发生和消退。 炎症然后，我们将这些研究转化为人类，因为我们的初步数据显示， 嗜酸性粒细胞增多（HE）病理学具有显著升高的MORBID水平。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MORBID是否控制人嗜酸性粒细胞 生存此外，使用来自HE患者的嗜酸性粒细胞，我们将确定增加的MORBID水平是否 会导致嗜酸性粒细胞增多总的来说，这些研究将描述一种新的机制， lncRNA决定小鼠中响应细胞外信号的短寿命髓样细胞的寿命 还有人类最终，我们希望利用这些调节机制的力量来获得治疗益处。

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.