The Role of Telomerase in Calcific Aortic Valve Disease

项目摘要 本研究旨在验证端粒酶逆转录酶（TERT）的非经典活性与细胞凋亡的关系。 通过诱导成骨重编程促进钙化性主动脉瓣疾病（CAVD）的钙化 瓣膜间质细胞（VIC）。我们的初步数据以及 其他人的工作。首先，人间充质干细胞中TERT的异位表达使这些细胞启动， 向下分化成骨谱系。其次，多项研究表明，TERT发挥非卡诺尼效应， cal功能，用于诱导基因表达，包括成骨基因的激活;这些活动是 与TERT的端粒延伸功能完全分离。第三，我们的初步数据显示， 与健康瓣膜相比，在CAVD瓣膜组织中表达，存在于从CAVD瓣膜分离的VIC中， 并且在促进成骨分化的条件下培养的健康VIC中上调。 第四，在体外模型中，TERT的基因缺失抑制了钙化，而敲低TERT则降低了钙化的发生。 成骨转录因子RUNX2的水平。最后，我们提供的证据表明，STAT5 可能参与TERT介导的成骨重编程激活。我们的数据识别出一种新的机甲- 驱动CAVD发病机制的基因。本提案的目的是确定TERT对CAVD的贡献 通过其非规范的行为。具体目标1将测试以下假设： 静止VIC向钙化VIC的转变。我们预计，基因缺失的端粒酶逆转录酶保护， 通过阻止静止的健康维克中心表型转变为成骨性钙化， 在维克。具体目标2将检验STAT5诱导TERT表达的假设，并且STAT5和 TERT协同诱导成骨基因的转录。我们期待着完成这些任务- 有意义的研究将确定一种调节CAVD发病机制的新机制，并将突出一种新的非CAVD机制， TERT在异位钙化中的作用。

PROJECT SUMMARY This project will test the hypothesis that non-canonical activities of telomerase reverse transcriptase (TERT) promote calcification in calcific aortic valve disease (CAVD) by inducing the osteogenic reprogramming of valve interstitial cells (VICs). Premise for this has been established from our preliminary data as well as from the work of others. First, ectopic expression of TERT in human mesenchymal stem cells primes these cells to differentiate down the osteogenic lineage. Second, multiple studies have shown that TERT exerts non-canoni- cal functions that act to induce gene expression, including activation of osteogenic genes; these activities are entirely separate from TERT’s telomere-extending functions. Third, our preliminary data shows TERT is highly expressed in CAVD valve tissues compared to healthy valves, is present in VICs isolated from CAVD valves, and is upregulated in healthy VICs that are cultured under conditions that promote osteogenic differentiation. Fourth, genetic deletion of TERT inhibits calcification in an in vitro model, and knockdown of TERT reduces levels of the osteogenic transcription factor RUNX2. Lastly, we provide evidence that suggests that STAT5 may be involved in the TERT-mediated activation of osteogenic reprogramming. Our data identify a new mech- anism driving CAVD pathogenesis. The objective of this proposal is to define TERT’s contribution to CAVD through its non-canonical actions. Specific Aim 1 will test the hypothesize that TERT is required for inducing the transition of quiescent VICs into calcifying VICs. We expect that genetic deletion of TERT protects against valvular calcification by preventing the phenotypic switch of a quiescent healthy VIC into an osteogenic calcify- ing VIC. Specific Aim 2 will test the hypothesis that STAT5 induces TERT expression, and together STAT5 and TERT cooperate to induce transcription of osteogenic genes. We expect the completion of these complemen- tary studies will identify a novel mechanism regulating CAVD pathogenesis, and will highlight a novel non-ca- nonical role for TERT in ectopic calcification.