Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Life Sci. 2020 Sep 15;257:118086. doi: 10.1016/j.lfs.2020.118086. Epub 2020 Jul 15.
To investigate the role of PP2A in calcified aortic valve disease (CAVD).
The expressions of PP2A subunits were detected by real-time polymerase chain reaction (RT-PCR) and western blot in aortic valves from patients with CAVD and normal controls, the activities of PP2A were analyzed by commercial assay kit at the same time. Aortic valve calcification of mice was evaluated through histological and echocardiographic analysis. ApoE mice and ApoE mice injected intraperitoneally with PP2A inhibitor LB100 were fed a high-cholesterol diet for 24 weeks. Immunofluorescent staining was used to locate the cell-type in which PP2A activity was decreased, the PP2A activity of valvular interstitial cells (VICs) treated with osteogenic induction medium was assessed by western blot and commercial assay kit. After changing the activity of VICs through pharmacologic and genetic intervention, the osteoblast differentiation and mineralization were assessed by western blot and Alizarin Red staining. Finally, the mechanism was clarified by using several specific inhibitors.
PP2A activity was decreased both in calcified aortic valves and human VICs under osteogenic induction. The PP2A inhibitor LB100 aggravated the aortic valve calcification of mice. Furthermore, PPP2CA overexpression inhibited osteogenic differentiation of VICs, whereas PPP2CA knockdown promoted the process. Further study revealed that the ERK/p38 MAPKs signaling pathways mediated the osteogenic differentiation of VICs induced by PP2A inactivation.
This study demonstrated that PP2A plays an important role in CAVD pathophysiology, PP2A activation may provide a novel strategy for the pharmacological treatment of CAVD.
研究蛋白磷酸酶 2A（PP2A）在钙化性主动脉瓣疾病（CAVD）中的作用。
通过实时聚合酶链反应（RT-PCR）和蛋白质印迹法检测 CAVD 患者和正常对照者主动脉瓣中 PP2A 亚基的表达，同时通过商业检测试剂盒分析 PP2A 的活性。通过组织学和超声心动图分析评估小鼠主动脉瓣钙化。用高脂饮食喂养载脂蛋白 E（ApoE）小鼠和腹腔内注射 PP2A 抑制剂 LB100 的 ApoE 小鼠 24 周。免疫荧光染色用于定位 PP2A 活性降低的细胞类型，通过蛋白质印迹法和商业检测试剂盒评估成骨诱导培养基处理的瓣膜间质细胞（VICs）中的 PP2A 活性。通过药理和遗传干预改变 VICs 的活性后，通过蛋白质印迹法和茜素红染色评估成骨细胞分化和矿化。最后，使用几种特定的抑制剂阐明机制。
在成骨诱导下，钙化主动脉瓣和人 VICs 中的 PP2A 活性均降低。PP2A 抑制剂 LB100 加重了小鼠主动脉瓣钙化。此外，PPP2CA 过表达抑制了 VIC 的成骨分化，而 PPP2CA 敲低则促进了该过程。进一步的研究表明，ERK/p38 MAPKs 信号通路介导了由 PP2A 失活诱导的 VIC 成骨分化。
本研究表明 PP2A 在 CAVD 病理生理学中起重要作用，PP2A 激活可能为 CAVD 的药物治疗提供新策略。
