钙结合和卷曲螺旋结构域2对血管紧张素Ⅱ诱导的房颤动物模型心房重构的影响及其机制

Effect of calcium binding and coiled-coil domain 2 on atrial remodeling in angiotensin II-induced atrial fibrillation animal models and its mecha⁃nism

目的:探讨钙结合和卷曲螺旋结构域2(calcium binding and coiled-coil domain 2,CALCOCO_(2))在心房颤动(atrial fibrillation,AF)动物模型的表达及其逆转AF小鼠心房重构的作用及机制。方法:将12只大鼠及12只小鼠各随机分为2组(n=6):盐水对照组(saline组)和血管紧张素II(angiotensin Ⅱ,Ang Ⅱ)诱导的AF组(Ang Ⅱ组)。利用Western blot及免疫组化检测CALCOCO_(2)在大、小鼠心房肌的表达。将另外24只小鼠按随机数字法均分为4组(n=6):saline-oeNC组、Ang II-oeNC组、saline-oeCALCOCO_(2)组和Ang II-oeCALCOCO_(2)组。利用腺相关病毒实现小鼠心肌CALCOCO_(2)过表达。经胸超声心动图和心内电生理检测小鼠心功能;Western blot和TUNEL染色评估CALCOCO_(2)对AF心肌细胞凋亡的影响;免疫组化评估CALCOCO_(2)对AF心房肌组织氧化应激[NADPH氧化酶2(NADPH oxidase 2,NOX2)和NOX4]及纤维化相关蛋白[I型胶原(collagen type I,Col I)、缝隙连接蛋白40(connexin 40,Cx40)和α-平滑肌肌动蛋白(α-smooth muscle actin,α-SMA)]的调控作用。结果:Western blot及免疫组化结果显示,与saline组相比,Ang II组大、小鼠心房肌CALCOCO_(2)水平显著降低(0.19±0.01 vs 0.32±0.03,0.37±0.10 vs 1.00±0.10,P<0.01)。心脏超声显示,与Ang II-oeNC组相比,Ang II-oeCALCOCO_(2)组小鼠左房内径显著缩小,AF持续时间显著缩短,射血分数显著提升(P<0.05)。TUNEL染色半定量分析显示,与Ang II-oeNC组相比,Ang II-oe-CALCOCO_(2)组小鼠心房肌细胞凋亡率显著降低(0.30±0.06 vs 0.61±0.03,P<0.01),这与BAX(1.94±0.34 vs 3.14±0.34)、cleaved caspase-3(2.19±0.41 vs 3.52±0.55)等凋亡相关蛋白的表达趋势一致(P<0.05)。免疫组化结果显示,与saline-oeNC组相比,Ang II-oeNC组氧化应激相关蛋白NOX2和NOX4及纤维化相关蛋白Col I和α-SMA水平显著升高,Cx40水平显著降低,而在CALCOCO_(2)过表达后这些蛋白水平被显著逆转(P<0.05)。结论:CALCOCO_(2)过表达可通过抑制小鼠心房氧化应激、凋亡及纤维化来逆转AF心房电重构和结构重构。

AIM:To explore the expression of calcium binding and coiled-coil domain 2(CALCOCO_(2))in ani-mal models of atrial fibrillation(AF)and its role and mechanism in reversing atrial remodeling in AF mice.METHODS:Twelve rats and 12 mice were randomly divided into the following 2 groups(n=6 each):saline control group(saline group)and angiotensin II(Ang II)-induced AF group(Ang II group).Western blot and immunohistochemistry(IHC)were used to detect CALCOCO_(2) expression in rat and mouse atrial muscle tissues.Another 24 mice were randomly divided into 4 groups(n=6 each):saline-oeNC,Ang II-oeNC,saline-oeCALCOCO_(2),and Ang II-oeCALCOCO_(2).An adeno-asso-ciated virus was used to induce CALCOCO_(2) overexpression in mouse atrial myocardium.Subsequently,transthoracic echocardiography and intracardiac electrophysiological testing were used to compare mouse cardiac function among the 4 groups.Western blot and TUNEL staining were also used to evaluate the effect of CALCOCO_(2) on apoptosis of cardiomyo-cytes in AF models.Additionally,IHC was used to assess the effect of CALCOCO_(2) on the levels of oxidative stress-related proteins[NADPH oxidase 2(NOX2)and NOX4]and fibrosis-related proteins[collagen type I(Col I),connexin 40(Cx40)andα-smooth muscle actin(α-SMA)]in AF atrial myocardium.RESULTS:The CALCOCO_(2) protein level in the atrial myocardium of rats and mice was significantly decreased in Ang II group compared with saline group,as detected by Western blot and IHC(0.19±0.01 vs 0.32±0.03 for rats,0.37±0.10 vs 1.00±0.10 for mice,P<0.01).Compared with Ang II-oeNC group,the mice in Ang II-oeCALCOCO_(2) group exhibited decreased left atrial inner diameter,shorter AF duration,and increased ejection fraction(P<0.05).Semi-quantitative analysis of TUNEL staining revealed a signifi-cantly decreased apoptosis rate of mouse atrial myocytes in Ang II-oeCALCOCO_(2) group compared with Ang II-oeNC group(0.30±0.06 vs 0.61±0.03,P<0.01),which was consistent with the Western blot trend of apoptosis-related proteins such as BAX(1.94±0.34 vs 3.14±0.34,P<0.05)and cleaved caspase-3(2.19±0.41 vs 3.52±0.55,P<0.05).The semi-quantitative results of IHC and immunofluorescence revealed significantly increased levels of oxidative stress-related pro-teins(NOX2 and NOX4)and fibrosis-related proteins(Col I andα-SMA),as well as decreased Cx40 levels,in Ang II-oeNC group compared with saline-oeNC group.However,the expression levels of these proteins were significantly re-versed after CALCOCO_(2) overexpression(all P<0.05).CONCLUSION:Overexpression of CALCOCO_(2) reverses AF-in-duced electrical and structural remodeling by inhibiting the oxidative stress,apoptosis and fibrosis in mouse atrial tissues.