LncRNA SNHG12, vascular senescence, and atherosclerosis

长链非编码RNA（lncRNA）作为多种生物学功能的新兴调节因子，已经引起了广泛的关注。 与动脉粥样硬化相关的生物学过程。然而，特定lncRNA的身份和作用， 动脉粥样硬化损伤没有很好地定义。使用RNA-Seq分析来鉴定特异性衍生的lncRNA 从LDLR-/-小鼠在病变进展和消退阶段的主动脉内膜中，我们鉴定了lncRNA， 小核仁宿主基因-12（SNHG 12）。SNHG 12在血管内皮细胞中高度富集， 随着动脉粥样硬化病变进展， 回归分析我们的初步研究表明，gapmeR介导的SNHG 12沉默有效地加速了SNHG 12的表达。 在LDLR-/-小鼠中动脉粥样硬化病变形成超过2倍。值得注意的是， 不是由降脂或病变白细胞的炎性募集驱动，而是由DNA增加驱动 血管内皮细胞损伤（γ H2 AX）和衰老（p16、p21、p27）。累积研究 表明由DNA损伤反应（DDR）诱导的血管衰老可能会不利地促进 动脉粥样硬化病变的慢性炎症。然而，衰老和衰老之间的联系机制， 动脉粥样硬化损伤形成仍然知之甚少。 LncRNA通过与RNA、染色质修饰剂或蛋白质相互作用而发挥重要的调控作用。 编码基因从机制上讲，使用改良的RNA IP（RIP）-质谱下拉分析，我们鉴定了 SNHG 12与DNA依赖性蛋白激酶（DNA-PK）相互作用以控制DNA损伤， 反应初步研究表明，内皮细胞中SNHG 12的缺乏显著增加了DNA损伤，标志物 以及EC对LDL的渗透性。此外，我们证明NAD+前体烟酰胺 抑制内皮细胞衰老的核苷（NR）可能以SNHG 12依赖性方式起作用。 这些观察结果为核心假设提供了基础，即内皮细胞SNHG 12缺陷，通过 对DNA-PK和DNA损伤反应的调节作用，促进血管衰老，衰老- 相关炎症和动脉粥样硬化。为了进一步阐明这一点，提出了三个目标。在AIM 1中，我们 将描述SNHG 12调节DNA-PK介导的DNA损伤反应能力的分子基础 和血管衰老。在Aim 2中，我们将确定改变lncRNA SNHG 12表达的影响。 以EC特异性方式对DNA损伤反应和动脉粥样硬化进展和消退起作用。在 目的3，我们将探讨刺激抑制和NR拯救SNHG 12的分子机制 我们将确定NR的抗衰老作用是否是SNHG 12依赖性的。 这个多学科团队在非编码RNA生物学、分子成像、纳米医学、 生物信息学和动脉粥样硬化研究将建立一个前所未有的分子观，这种lncRNA， 这些病变可以为血管衰老和动脉粥样硬化的调节提供新的前沿信息。

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 Small Nucleolar Host Gene-12 (SNHG12). SNHG12 is highly enriched in the vascular endothelium across mice, pigs, and humans and is significantly reduced with atherosclerotic lesion progression, but increased with regression. Our preliminary studies show that gapmeR-mediated silencing of SNHG12 potently accelerated atherosclerotic lesion formation by over 2-fold in LDLR-/- mice. Remarkably, the increased lesional effects were not driven by lipid-lowering or by inflammatory recruitment of lesional leukocytes, but rather by increased DNA damage (γH2AX) and senescence (p16, p21, p27) in the vascular endothelium. Accumulating studies demonstrate that vascular senescence induced by the DNA damage response (DDR) may adversely contribute to chronic inflammation in atherosclerotic lesions. However, the mechanisms linking senescence and atherosclerotic lesion formation remain poorly understood. LncRNAs play important regulatory roles by interacting with RNA, chromatin modifiers, or protein- coding genes. Mechanistically, using a modified RNA IP (RIP)-mass spectrometry pulldown assay, we identify that SNHG12 interacts with the DNA-dependent protein kinase (DNA-PK) to control the DNA-damage response. Preliminary studies show SNHG12 deficiency in ECs significantly increased DNA damage, markers of senescence, and EC permeability to LDL. Moreover, we demonstrate that the NAD+ precursor nicotinamide riboside (NR), that suppresses endothelial senescence, may function in an SNHG12-dependent manner. These observations provide the foundation for the central hypothesis that endothelial SNHG12 deficiency, via regulatory effects on DNA-PK and the DNA damage response, promotes vascular senescence, senescence- associated inflammation, and atherosclerosis. To elucidate this further, three aims are proposed. In Aim1, we will delineate the molecular basis for SNHG12's ability to regulate DNA-PK-mediated DNA damage response and vascular senescence in ECs. In Aim2, we will determine the effect of altering lncRNA SNHG12 expression in an EC-specific manner on the DNA damage response and atherosclerotic progression and regression. In Aim3, we will explore the molecular mechanisms by which stimuli repress and NR rescues SNHG12 expression in ECs, and we will determine whether the anti-senescent effects of NR are SNHG12-dependent. This multi-disciplinary team in the fields of non-coding RNA biology, molecular imaging, nanomedicine, bioinformatics, and atherosclerosis research will establish an unprecedented molecular view of this lncRNA in lesions that can inform a new frontier in the regulation of vascular senescence and atherosclerosis.