corin蛋白及其编码基因启动子区DNA甲基化与脑卒中关系的前瞻性队列研究

Human corin, a type II transmembrane serine protease highly expressed in the heart, plays a critical role in the activation of pro-atrial natriuretic peptide (pro-ANP) and pro-brain natriuretic peptide (pro-BNP), both of which are key components of natriuretic peptides system. Cell- and animal-based studies found that corin deficiency may cause blood pressure elevation. Genetic studies reported significant associations of CORIN gene polymorphisms with hypertension and obesity. Our prior case-control study found that soluble corin was significantly lower in stroke patients than that in healthy controls. All these findings suggested an association between soluble corin and stroke risks. In addition, as a mediator between genome and environment, DNA methylation could influence gene expression and function. Therefore, CORIN gene promoter methylation may also participate in the pathogenesis of stroke. However, the causal relationship between soluble corin, CORIN gene methylation, and stroke is uncertain. Therefore, we propose to conduct a prospective cohort study to examine the temporal associations of soluble corin and CORIN gene promoter methylation with the risk of stroke, leveraging our existing cohort and baseline data of soluble corin. Only need additionally obtaining CORIN gene promoter methylation at baseline and stroke events at follow-up, can we complete this proposed project. By using causal mediation analysis, we aimed to confirm the temporal association between soluble corin and incident stroke and find functional epigenetic determinants of stroke on the CORIN gene promoter. Our proposed study would definitely provide critical evidence for the potential of corin deficiency and CORIN gene methylation as a novel modifiable risk factor of stroke. Moreover, the findings of our proposed study may bring insight into potential mechanisms and drug targets of stroke.

corin具有活化pro-ANP和pro-BNP的生物活性，是利钠肽轴的关键蛋白。动物实验显示，corin缺乏导致血压升高；人群研究显示，CORIN基因多态性与高血压和肥胖相关联；申请者前期的病例对照研究发现，可溶性corin水平在脑卒中患者中显著低于健康对照。这些研究结果均提示corin缺乏可能是脑卒中的新危险因素和潜在干预靶点。另外，作为连接基因和环境的媒介，DNA甲基化可以调控基因的表达和功能，CORIN基因DNA甲基化也可能在脑卒中发病过程中发挥作用。但是，corin缺乏以及CORIN基因DNA甲基化与脑卒中发病的因果关系尚不明确。本申请项目拟在已有的人群基线corin水平和前瞻性队列的基础上，对队列人群继续随访并进行基线CORIN基因启动子区DNA甲基化检测，采用因果中介分析方法，确证可溶性corin水平降低以及CORIN基因启动子区DNA甲基化与脑卒中发病风险的时间先后关系。

利钠肽轴在维持机体水钠平衡、血压稳定和能量代谢平衡方面发挥着重要作用，主要由心房钠尿肽（atrial natriuretic peptide, ANP）和脑钠尿肽（brain natriuretic peptide, BNP）以及他们的受体构成。corin是一种主要由心肌细胞分泌的丝氨酸蛋白酶，是将pro-ANP活化为ANP的生理性转化酶，近来，又有研究发现corin也可活化pro-BNP。可见，corin位于利钠肽轴的最顶端，调控着利钠肽轴的功能，可能是脑卒中的新危险因素和潜在干预靶点，然而，尚未见关于可溶性corin与脑卒中关系的前瞻性研究报道，而且，corin缺乏与脑卒中相关联的分子机制也不清楚。作为连接基因与环境的媒介，DNA甲基化调控着基因的表达和功能，作为corin的编码基因，CORIN基因启动子区DNA甲基化可能抑制corin表达，引起corin缺乏，从而参与脑卒中的发病过程，但目前尚未见关于CORIN基因甲基化与脑卒中相关性的研究报道。本研究在“姑苏区高血压监测与防治队列研究”（n=2498）的基础上开展了一项前瞻性队列研究，用ELISA试剂盒检测基线时可溶性corin水平，对保存的基线DNA标本进行目标区域甲基化检测，获得CORIN基因启动子区域9个CpG位点DNA甲基化水平，分析基线时可溶性corin水平和CORIN基因启动子区DNA甲基化水平与脑卒中发病风险的关系。在10年的随访期间，有88人发生了脑卒中事件、50人非脑卒中死亡、214人失访，随访率达91.43%。可溶性corin水平每增加10倍，脑卒中事件发生风险增加2.19倍（HR=3.19，P=0.014）。校正传统危险因素和多重检验后，在检测的9个CpG位点中，CpG3甲基化水平与脑卒中的关系仍然存在，该位点甲基化水平每增加2倍，脑卒中发生风险减少29%（HR=0.707，P=0.017），但未发现该位点甲基化水平对可溶性corin与脑卒中关系的中介效应。这些结果提示，在中国汉族人群中，基线时血清corin水平升高可以独立预测较高的脑卒中发病风险，基线时CORIN基因启动子区域Chr4:47840038位点DNA甲基化水平升高与脑卒中发病风险降低有关。但是，corin与脑卒中的因果关系尚需进一步研究证据