LncRNA MAARS, macrophage apoptosis, and atherosclerosis

动脉粥样硬化是一种慢性动脉疾病，涉及多个细胞过程，包括 内膜巨噬细胞随着动脉粥样硬化的进展，巨噬细胞凋亡增加，导致 增加细胞死亡和细胞碎片积累。这反过来又可以消除巨噬细胞巨噬细胞增多， 这是清除凋亡或坏死细胞的重要事件。因此，提高效率 巨噬细胞清除病灶内细胞碎片可能提供一种新的治疗方法， 动脉粥样硬化进展。 长链非编码RNA（lncRNA）作为新出现的转录调控因子已经引起广泛关注。 与动脉粥样硬化相关的多种生物学过程。然而，特异性lncRNA的身份和作用 在动脉粥样硬化病变内没有很好的定义。使用RNA-Seq分析来鉴定来源于 特别是从LDLR-/-小鼠的主动脉内膜在病变进展和消退阶段，我们确定 lncRNA MAARS（巨噬细胞相关动脉粥样硬化lncRNA序列）。MAARS最高 表达lncRNA，在病变进展后增加300倍，随着消退下降70%。 MAARS是一种多聚腺苷酸化的巨噬细胞和核特异性lncRNA。动力学研究表明， 在从骨髓、PBMC或脾细胞分化的巨噬细胞中显著诱导表达。 我们的初步数据表明，对MAARS系统性递送抑制剂可显著减小病变大小， 独立于对循环脂质谱的影响，而是通过减少巨噬细胞凋亡和 血管壁红细胞增多。MAARS缺陷减少了由 不同的刺激和体外增加的巨噬细胞吞噬作用。从机制上讲，lncRNA下拉试验在 结合LC-MS/MS分析表明，MAARS与RNA结合蛋白HuR相互作用， 细胞凋亡的重要调节因子。初步研究表明HuR沉默增加巨噬细胞凋亡 MAARS对巨噬细胞凋亡的影响可能是HuR依赖性的。此外，MARS 敲低改变了HuR的核质运输，并调节重要的凋亡基因。这些 观察结果为中心假设提供了基础，即MAARS缺陷，通过对 HuR和特定的巨噬细胞凋亡信号通路，减少巨噬细胞凋亡，改善细胞凋亡， 抑制动脉粥样硬化。为了进一步解决这个问题，在Aim 1中，我们研究了MAARS的作用 在调节HuR介导的巨噬细胞凋亡和巨噬细胞增多中;在Aim 2中，我们评估了 MAARS表达影响体内短期和长期动脉粥样硬化;在Aim 3中，我们研究了MAARS表达的作用。 人细胞和动脉粥样硬化病变中的MAARS-HuR信号轴。我们的研究将解决一个主要的 我们对lncRNA在动脉粥样硬化中的理解存在差距，并告知MAARS介导的对动脉粥样硬化的控制 巨噬细胞凋亡和巨噬细胞增多可能为治疗提供新的靶点。

Atherosclerosis, a chronic arterial disease, involves multiple cellular processes including the accumulation of intimal macrophages. Macrophage apoptosis is increased with progression of atherosclerosis, leading to increased cell death and accumulation of cellular debris. This in turn may abrogate macrophage efferocytosis, an important event for clearance of apoptotic or necrotic cells. Therefore, improving the efficiency of macrophages in the clearance of intra-lesional cellular debris may provide a novel therapeutic approach to limit atherosclerotic progression. Long non-coding RNAs (lncRNAs) have garnered widespread attention as emerging regulators of diverse biological processes relevant to atherosclerosis. However, the identity and roles of specific lncRNAs within atherosclerotic lesions are not well defined. Using RNA-Seq profiling to identify lncRNAs derived specifically from the aortic intima of LDLR-/- mice during lesion progression and regression phases, we identify the lncRNA MAARS (Macrophage-Associated Atherosclerosis lncRNA Sequence). MAARS was the highest expressed lncRNA with a 300-fold increase after lesion progression and decreased by 70% with regression. MAARS is a polyadenylated, macrophage- and nuclear-specific, lncRNA. Kinetic studies showed that MAARS expression is markedly induced in macrophages differentiated from bone marrow, PBMCs, or splenocytes. Our preliminary data demonstrate that systemic delivery of inhibitors to MAARS strongly reduced lesion size, independent of effects on circulating lipid profile, but rather by decreased macrophage apoptosis and increased efferocytosis in the vessel wall. Deficiency of MAARS reduced macrophage apoptosis induced by different stimuli and increased macrophage efferocytosis in vitro. Mechanistically, lncRNA pulldown assays in combination with LC-MS/MS analysis showed that MAARS interacts with HuR, an RNA-binding protein and important regulator of apoptosis. Preliminary studies show that HuR silencing increases macrophage apoptosis and that the MAARS-mediated effects on macrophage apoptosis may be HuR dependent. In addition, MAARS knockdown altered HuR nuclear-cytoplasmic trafficking, and regulated important apoptotic genes. These observations provide the foundation for the central hypothesis that MAARS deficiency, via regulatory effects on HuR and specific macrophage apoptotic signaling pathways, reduces macrophage apoptosis, improves cellular efferocytosis, and suppresses atherosclerosis. To address this further, in Aim1 we examine the role of MAARS in regulating HuR-mediated macrophage apoptosis and efferocytosis; in Aim2, we assess how alterations of MAARS expression affects short- and long-term atherosclerosis in vivo; and in Aim3, we examine the role of the MAARS-HuR signaling axis in human cells and atherosclerotic lesions. Our studies will address a major gap in our understanding of lncRNAs in atherosclerosis and inform how MAARS-mediated control of macrophage apoptosis and efferocytosis may provide new targets for therapy.