利钠肽受体1调节血管内皮细胞衰老的分子机制

Aging is an important risk factor for hypertension and elevation of blood pressure is a key functional feature for vascular aging. We first reported that proprotein convertase subtilisin/kexin-6 (PCSK6) activating atrial natriuretic peptide convertase, which cleaves atrial natriuretic peptide (ANP), is essential for regulating blood pressure. The signaling pathway controls vascular function via binding natriuretic peptide receptor 1 (NPR1) in its downstream. Recently, we found that NPR1 expression was reduced in replicative senescence and aged vascular endothelial cells. Knock-down of NPR1 increased cell senescence in the endothelial cells, suggesting that NPR1 is involved in vascular aging. In the proposed study, we will aim at the molecular mechanism of NPR1 in regulating vascular endothelial cells. We will test four specific aims: 1) To search for NPR1-relaed genes involved in vascular aging through RNA-SEQ and functional analysis using NPR1 knockout endothelial cells; 2) To examine the mechanism of regulation of NPR1 expression in vascular senescence; 3) To determine the effect of NPR1 in endothelial cells during aging process; 4) To evaluate the function of NPR1 in vascular aging in vivo by Npr1CRISPR/Cas9 knockout mice. This line of study may provide a new molecular target for improvement of age-related vascular disease.

老龄化是高血压的重要危险因素，而血压升高是血管衰老的重要功能特征。我们首次报道前蛋白转化酶枯草溶菌素6(PCSK6)激活心钠肽转换酶产生活性心钠肽(ANP)是调控血压的关键通路(Chen et al. Nat Med, 2015)。该途径通过激活下游的利钠肽受体1(NPR1)调节血管舒缩功能。我们最近发现NPR1在复制型衰老和老年血管内皮细胞中表达降低，敲低NPR1导致内皮细胞衰老，说明NPR1参与血管衰老的调节。本项目拟研究NPR1调节血管内皮细胞衰老的分子机制, 内容包括1)对NPR1敲除内皮细胞进行转录组测序及功能分析，寻找与NPR1相关的且参与衰老的信号通路；2)确定NPR1参与衰老表达的调控机理；3)确定NPR1在衰老中对内皮细胞功能的影响；4)建立Npr1CRISPR/Cas9敲除小鼠模型，研究NPR1在体参与调节血管衰老的机制。为改善衰老相关血管疾病提供可能的新的分子靶点。

血管衰老是高血压的关键风险因素，而内皮细胞衰老是血管衰老的驱动环节。目前尚不清楚衰老是如何影响血管功能并导致高血压。利钠肽受体1(NPR1，又称NPRA)是血压及血管稳态的调节器。本项目主要研究NPR1在内皮细胞衰老中的作用及参与血管衰老的调控机理，并对NPR1敲低的内皮细胞进行转录组测序及功能分析，寻找与NPR1相关且参与衰老的新基因和信号通路，建立Npr1CRISPR/Cas9敲除小鼠模型探讨NPR1在体参与调节血管衰老的机制。我们发现(1)NPR1的表达随着内皮细胞和血管衰老逐渐降低；NPR1缺乏可通过抑制其下游信号分子蛋白激酶G(PKG)/磷酸腺苷活化蛋白激酶(AMPK)，减少烟酰胺腺嘌呤二核苷酸(NAD+)的合成及增加活性氧(ROS)的产生,加速内皮细胞衰老进程；(2) Npr1敲除小鼠出现血管衰老表型，血管内皮依赖性舒张功能减弱，收缩压明显升高，表明NPR1的缺乏引起血管内皮细胞功能障碍，促进血管衰老。激活PKG或AMPK可拮抗NPR1减少引起的内皮细胞衰老和血管衰老，改善血管功能，缓解高血压。(3)发现DNA复制和姐妹染色单体内聚1(DSCC1)是与NPR1相关的参与内皮细胞衰老的新基因，敲低DSCC1诱导内皮细胞及血管衰老，过表达DSCC1减弱Npr1缺失导致的血管衰老表型，表明DSCC1在调节血管衰老过程中起着重要的作用。(4)筛选出与NPR1基因启动子相互作用的转录因子ETS1，可能参与NPR1调控细胞衰老的过程。本项目在细胞水平和动物模型中证明NPR1调节内皮细胞和血管衰老。NPR1/PKG/AMPK这一新的关键信号轴，在减缓血管衰老和年龄相关性血管功能障碍如高血压中发挥着至关重要的作用。并且可能为药物干预与临床治疗提供潜在的分子靶点。