MK2基因在高血压小鼠左心室重塑中的作用及机制研究

Role and mechanism of MK 2 gene in left ventricular remodeling of hypertensive mice

目的:研究丝裂原活化蛋白激酶激活的蛋白激酶2(MK2)基因在高血压小鼠左心室重塑中的作用及机制。方法:野生型C57BL/6J小鼠随机分为MK2^(+/+)组、MK2^(+/+)AAC组,MK2基因敲除C57BL/6J小鼠随机分为MK2^(-/-)组、MK2^(-/-)AAC组,采用腹主动脉缩窄术(AAC)建立高血压左心室重塑模型小鼠。检测各组小鼠的收缩压(SBP)、心脏超声指标舒张末期左室前壁厚度(LVAWd)、收缩末期左室前壁厚度(LVAWs)、舒张末期左室后壁厚度(LVPWd)、收缩末期左室后壁厚度(LVPWs)、心肌厚度、心脏/体质量(HW/BW)、心肌HE染色、Masson染色及心肌胶原容积分数(CVF)、血清中脑型脑钠肽(BNP)、血管紧张素Ⅱ(AngⅡ)、醛固酮(ALD)含量、心肌中Ⅰ型胶原(Col-Ⅰ)、Col-Ⅲ、α-平滑肌肌动蛋白(α-SMA)的mRNA表达水平、MK2、NF-κB、Cleaved caspase-3蛋白表达水平、活性氧簇(ROS)、TNF-α、IL-6、总抗氧化力(T-AOC)含量。结果:与MK2^(+/+)组比较,MK2^(+/+)AAC组小鼠的SBP、LVAWd、LVAWs、LVPWd、LVPWs、心肌厚度、HW/BW、CVF水平及心肌中MK2、NF-κB、Cleaved caspase-3蛋白表达水平、Col-Ⅰ、Col-Ⅲ、α-SMA mRNA表达水平、TNF-α、IL-6、ROS含量明显增加,心肌中T-AOC含量明显降低(P<0.05);MK2^(-/-)组各项指标差异均无统计学意义(P>0.05)。与MK2^(+/+)AAC组比较,MK2^(-/-)AAC组小鼠SBP水平无明显变化(P>0.05),LVAWd、LVAWs、LVPWd、LVPWs、心肌厚度、HW/BW、CVF水平及心肌中MK2、NF-κB、Cleaved caspase-3蛋白表达水平、Col-Ⅰ、Col-Ⅲ、α-SMA mRNA表达水平、TNF-α、IL-6、ROS含量明显降低,心肌中T-AOC含量明显增加(P<0.05)。结论:MK2基因高表达与高血压小鼠左心室重塑有关,激活MK2下游炎症反应、氧化应激反应、细胞凋亡是相关的分子机制。

Objective:To investigate role and mechanism of mitogen-activated protein kinase activated protein kinase 2(MK2)gene in left ventricular remodeling of hypertensive mice.Methods:Wild type C57BL/6J mice were randomly divided into MK2^(+/+)group and MK2^(+/+)AAC group.MK2 gene knockout C57BL/6J mice were randomly divided into MK2^(-/-)group and MK2^(-/-)AAC group.Hypertensive and left ventricular remodeling model mice were established by abdominal aortic coarctation(AAC).Systolic blood pressure(SBP),left ventricular anterior wall thickness at end-diastole(LVAWd),left ventricular anterior wall thickness at end-systole(LVAWs),left ventricular posterior wall thickness at end-diastole(LVPWd),left ventricular posterior wall thickness at end-systole(LVPWs),myocardial thickness,heart and body weight ratio(HW/BW),myocardial HE staining,Masson staining and myocardial collagen volume fraction(CVF),contents of brain natriuretic peptide(BNP),angiotensinⅡ(AngⅡ)and aldosterone(ALD)in serum,mRNA expressions of collagenⅠ(Col-Ⅰ),Col-Ⅲandα-smooth muscle actin(α-SMA),protein expressions of MK2,NF-κB,Cleaved caspase-3,contents of reactive oxygen species(ROS),TNF-α,IL-6 and total antioxidant capacity(T-AOC)in myocardial tissues were determined.Results:Compared with MK2^(+/+)group,levels of SBP,LVAWd,LVAWs,LVPWd,LVPWs,myocardial thickness,HW/BW,CVF and protein expressions of MK2,NF-κB,Cleaved caspase-3,mRNA expressions of Col-Ⅰ,Col-Ⅲ,α-SMA,contents of TNF-α,IL-6 and ROS were significantly increased,while content of T-AOC was significantly decreased in MK2^(+/+)AAC group(P<0.05);there was no significant difference in the above indexes between MK2^(+/+)group and MK2^(-/-)group(P>0.05).Compared with MK2^(+/+)AAC group,level of SBP had no significant difference(P>0.05),levels of LVAWd,LVAWs,LVPWd,LVPWs,myocardial thickness,HW/BW,CVF and protein expressions of MK2,NF-κB,Cleaved caspase-3,mRNA expressions of Col-Ⅰ,Col-Ⅲ,α-SMA,contents of TNF-α,IL-6 and ROS were significantly decreased,while content of T-AOC was significantly increased in MK2^(-/-)AAC group(P<0.05).Conclusion:High expression of MK2 gene is associated with left ventricular remodeling in hypertensive mice.Activation of inflammation,oxidative stress and apoptosis in the downstream of MK2 is the responsible molecular mechanism.