Telomerase Reverse Transcriptase in Vascular Homeostasis

血管内皮细胞在协调多种循环中起着至关重要的作用 血液流动、血栓形成、白细胞运输，甚至新陈代谢等功能。正常 内皮功能的特征是静止的细胞表型是非增殖性的， 非迁移性，细胞表面可防止血栓形成、炎症和脂质 沉积，从而抵抗动脉粥样硬化和血管疾病。一把稳定的钥匙 内皮静止的刺激是细胞上的层流流体剪应力(FSS) 直的血管节段的一个特征。相比之下，弯曲的和 分支动脉会经历混乱的FSS，称为扰流，这意味着 稳定的、激活的、更容易发生动脉粥样硬化的内皮表型。这个 控制内皮细胞表型对流体剪切力的反应的机制是 不完全理解。在这个应用中，我们提供了过氧化物酶增殖物的数据 γ-辅活化子-1α(Pgc1α)是一种内皮细胞内的流体切应力反应因子，是一种 随着层流上升，但不是振荡的FSS。Pgc1α上调对人卵巢癌 激活与正常血管内稳态有关的关键通路，如KLF2、Notch和 ENOS促进稳定的抗动脉粥样硬化内皮细胞表型。激动人心的导频数据 这种效应与端粒酶逆转录酶(TERT)及其受体的上调有关 核外，端粒长度无关，功能稳定维持 线粒体动态平衡对层流FSS的响应。内皮细胞缺乏TERT活性 显示线粒体碎裂，无法与血流对齐，这是需要的关键功能 来抵抗动脉粥样硬化。总而言之，这些数据促使我们的核心假设 内皮细胞PGC1TERT信号转导是内皮和血管适应所必需的α-TERT信号通路 切变和正常的血管动态平衡。为了研究这一假设，我们建议首先 确定前列腺素C_1α如何影响体内血管内皮细胞对fss的反应 他莫昔芬诱导的Cre/Lox系统产生内皮细胞特异性的Pgc1α基因切除 原位共聚焦显微镜、单细胞RNA序列、网络医学与载脂蛋白E/动脉粥样硬化 模特。同样，我们将对诱导性内皮细胞TERT基因切除使用相同的策略。 最后，使用缺乏Pgc1α或TERT的细胞培养，我们将剖析 前列腺素C1TERT信号转导影响内皮细胞α反应性的机制 特别关注FSS诱导的Pgc1α基因组占位，线粒体和细胞代谢， 内皮细胞流动排列，以及TERT定位于细胞核与线粒体。 总的来说，这些研究将提供对内皮细胞新范式的洞察 对FSS的反应性和维持静止内皮单分子层的要求 抵抗血管疾病。有了这些信息，我们应该有必要的洞察力来设计新的 减少血管疾病的发病率和死亡率的治疗。

The vascular endothelium plays an essential role in coordinating diverse circulatory functions such as blood flow, thrombosis, leukocyte trafficking, and even metabolism. Normal endothelial function is characterized by a quiescent cell phenotype that is non-proliferative, non-migratory, and exhibits a cell surface that prevents thrombosis, inflammation, and lipid deposition, thereby resisting atherosclerosis and vascular disease. A key stabilizing stimulus for endothelial quiescence is laminar fluid shear stress (FSS) on the cell surface that is a feature of straight vascular segments. In contrast, curved and branching arteries experience chaotic FSS, called disturbed flow, that dictates a less stable, activated, endothelial phenotype that is more susceptible to atherosclerosis. The mechanisms governing endothelial phenotype in response to fluid shear stress are incompletely understood. In this application, we present data that peroxisome proliferator gamma coactivator-1α (PGC1α), is a fluid shear stress-responsive factor in endothelium that is upregulated with laminar, but not oscillatory FSS. Upregulation of PGC1α is important for the activation of key pathways linked to normal vascular homeostasis such as Klf2, Notch, and eNOS that promote a stable anti-atherosclerotic endothelial phenotype. Exciting pilot data links this effect to upregulation of telomerase reverse transcriptase (TERT) and its extra-nuclear, telomere length-independent, function to stabilize maintain mitochondrial homeostasis in response to laminar FSS. Endothelium lacking TERT activity shows mitochondrial fragmentation and fails to align with flow, a key function needed to resist atherosclerosis. Collectively, these data prompt our central hypothesis that endothelial PGC1α-TERT signaling is required for endothelial and vascular adaptation to shear and normal vascular homeostasis. To investigate this hypothesis, we propose to first determine how PGC1α influences endothelial responses to FSS in vivo using a tamoxifen-inducible Cre/Lox system producing endothelial specific PGC1α-gene excision, in situ confocal microscopy, single-cell RNA-seq, Network Medicine, and the ApoE-/- atherosclerosis model. Similarly, we will use the same strategy with inducible endothelial TERT gene excision. Finally, using cell culture of cells lacking either PGC1α or TERT, we will dissect the mechanisms whereby PGC1α-TERT signaling impacts endothelial FSS responsiveness with a particular focus on FSS-induced PGC1α genome occupancy, mitochondrial and cellular metabolism, endothelial cell flow alignment, and TERT localization to the nucleus vs. mitochondria. Collectively, these studies will provide insight into a new paradigm of endothelial cell responsiveness to FSS and the requirements to maintain a quiescent endothelial monolayer that resists vascular disease. With this information, we should have the requisite insight to design new therapies to alleviate morbidity and mortality from vascular disease.