慢性肾脏病前列腺素E2通过激活β-catenin信号通路介导心肌肥厚的分子机制及干预研究

Patients with chronic kidney disease (CKD) are at significantly increased risk for both morbidity and mortality from cardiovascular disease. Cardiac hypertrophy is the common pathological feature for cardiac complications in CKD. However, the pathophysiology of cardiac hypertrophy in patients with CKD remains unclear. Our previous study found that: 1) Serum levels of PGE2 were increased in patients with CKD, and positively correlated with the severity of CKD and cardiac hypertrophy; 2) In vitro experiments demonstrated that PGE2 could activate β-catenin and induce cardiomyocyte hypertrophy through PI3K/AKT and PKA pathway, rather than through transactivate EGFR. Based on these findings, the present project will continue to explore: 1) Since there are 4 EP receptors (EP1-EP4) mediating PGE2 signaling, we will examine which receptor mediate PGE2 induced β-catenin activation and cardiomyocyte hypertrophy; 2) 5/6 nephrectomy is a classical model for CKD. By using COX2 inhibitor to suppress PGE2 synthesis, selective EP2 and EP4 receptor inhibitor and β-catenin inhibitor, we try to examine the functional role of PGE2-EP receptor -PI3K/AKT, PKA-β-catenin signaling pathway in cardiac hypertrophy associated with CKD. These findings will certainly provide new therapeutic strategies and targets for cardiac hypertrophy and cardiovascular events in CKD.

慢性肾脏病（CKD）导致的心血管事件发生率和死亡率居高不下，心肌肥厚是CKD心脏并发症的共同病理基础，然而CKD心肌肥厚的病理生理学机制仍不清楚。我们前期研究发现：1）CKD患者血清PGE2水平显著升高，且与肾功能的严重程度及左室肥厚呈正相关；2）体外培养心肌细胞实验发现，PGE2通过启动PI3K/AKT和PKA信号通路而不是通过转激活EGFR，诱导β-catenin活化，介导心肌细胞肥大。在此基础上，本项目将进一步探讨：1）PGE2与何种EP受体结合介导β-catenin的激活。2）以5/6肾切除为CKD模型，分别使用COX2抑制剂抑制PGE2合成，EP2和EP4受体抑制剂阻断EP受体以及β-catenin抑制剂，在体内证实PGE2－EP受体－PI3K/AKT和PKA－β-catenin信号通路在CKD心肌肥厚中的作用，从而为CKD心肌肥厚以及心血管事件提供新的干预策略和靶点。

【背景】慢性肾脏病（chronic kidney disease，CKD）是严重威胁人类健康的重大疾病，是公认的“全球公共健康问题”。CKD导致的心血管事件发生率和死亡率居高不下，心肌肥厚是CKD心脏并发症的共同病理基础，然而CKD心肌肥厚的病理生理学机制仍不清楚。【方法】 研究中，细胞实验采用荧光定量PCR、免疫印迹等验证PGE2通过EP受体诱导心肌细胞β-catenin激活。体内实验，我们构建5/6肾切除大鼠模型，通过ELISA检测2-4-8-12周PGE2的分泌情况，以及心超检测相应周龄大鼠心肌肥厚程度、β-MHC的表达以及β-catenin蛋白表达的变化。此外，通过药物干预，研究相应药物对CKD大鼠心肌肥厚的影响。【结果】研究证实（1）PGE2刺激心肌细胞后，通过结合EP2和EP4受体（主要是EP2受体），而非EP1和EP3受体，激活β-catenin。（2）在5/6 NT SD大鼠中，8周后PGE2水平显著升高，反应心肌肥厚指标β-MHC、ANP相应升高，β-catenin及PKA表达升高。（3）通过阻断EP2受体和β-catenin蛋白的表达，可以明显减轻心肌肥厚。【结论】PGE2通过EP2/EP4受体－AKT－β-catenin信号通路介导心肌肥厚，从而为CKD心肌肥厚以及心血管事件提供新的干预策略和靶点。.