Gsα在肥厚心肌中的表达及敲除后对心脏发育的影响  

Expression of Gsαin mice with cardiac hypertrophy and effects of cardiac-specific Gsαdeletion on heart development in young mice

作　　者：银萍 赵奇 石毓君[2] 苏立[1] YIN Ping;ZHAO Qi;SHI Yujun;SU Li(Department of Cardiology,the Second Affiliated Hospital of Chongqing Medical University,Chongqing,400014;Department of Pathology,West China Hospital of Sichuan University,Chengdu,Sichuan Province,610041,China)

机构地区：[1]重庆医科大学附属第二医院心血管内科,重庆400014 [2]四川大学华西医院病理研究室,成都610041

出　　处：《第三军医大学学报》2021年第14期1319-1325,共7页Journal of Third Military Medical University

基　　金：国家自然科学基金面上项目(81974036)。

摘　　要：目的通过主动脉缩窄术(transverse aortic constriction, TAC)建立压力超负荷诱导心肌肥厚的小鼠模型,检测肥厚心肌组织中Gsα表达变化,同时构建诱导性心肌特异性Gsα缺失小鼠,观察Gsα缺失对幼鼠心肌发育的影响。方法 10只健康雄性C57BL/6小鼠,按随机数字表法分为手术组(TAC组,n=5)和假手术组(Sham组,n=5),TAC组小鼠行主动脉弓缩窄术,Sham组小鼠仅穿线而不缩窄主动脉。术后4周,采用超声心动图检测小鼠左心功能,运用病理组织染色观察小鼠心肌结构变化,利用RT-qPCR及Western blot检测小鼠心肌组织中Gsα表达;采用Cre-Loxp系统,将Gsα~(fl/fl)小鼠与Myh6-MerCreMer小鼠杂交获得诱导性Myh6-MerCreMer~(+/-)/Gsα~(fl/fl)(MCM/Gsα~(fl/fl))小鼠。哺乳期MCM/Gsα~(fl/fl)小鼠予腹腔注射他莫昔芬(tamoxifen, TMX, 20 mg/mL),连续10 d,通过哺乳方式将TMX传递给幼鼠,构建诱导性心肌特异性Gsα缺失幼鼠。记录幼鼠体质量增长以及生存率,利用病理组织染色观察心肌的结构变化。结果术后4周,超声心电图结果显示TAC组小鼠较Sham组小鼠舒张末期左室后壁增厚(P<0.01)、舒张末期室间隔增厚(P<0.05)、舒张末期左室内径减小(P<0.05),提示心肌发生了代偿性肥厚;组织病理学检测提示TAC组小鼠心肌横截面积显著增大(P<0.01),血管周围纤维化明显增加(P<0.01);RT-qPCR以及Western blot结果提示GsαmRNA及蛋白表达水平增加(P<0.05)。与玉米油诱导对照组相比,TMX诱导Gsα缺失的幼鼠出现生长迟缓、体质量显著降低(P<0.05);组织学染色提示TMX诱导的幼鼠心脏大小明显减小。结论 Gsα在压力超负荷诱导心肌肥厚心肌中的表达上调。Gsα敲除后幼鼠生长延迟、心脏发育受阻,提示Gsα可能参与心脏生理发育及后负荷增加所致代偿性心肌肥厚过程。Objective To detect the expression profile of alpha-subunit of the stimulatory G protein(Gsα)in a mouse model of pressure overload-induced cardiac hypertrophy by transverse aortic constriction(TAC),and investigate the effects of cardiac-specific Gsαdeletion on the cardiac development in young mice.Methods Ten healthy adult male C57 BL/6 mice were randomized equally into model group(TAC)and sham operation(Sham)group.The mice of the TAC group were inflicted with TAC to construct a mouse model of pressure overload induced myocardial hypertrophy.Four weeks after surgery,echocardiography was employed to assess the left cardiac function,histopathological staining was used to observe the myocardial structure,and RT-qPCR as well as Western blotting were performed to detect the expression of Gsαin the myocardial tissues of the mice.In addition,a Myh6-MerCreMer+/-/Gsαfl/fl(MCM/Gsαfl/fl)mouse model was established by hybridization of Gsαfl/fl mice and Myh6-MerCreMer mice using Cre/Loxp system.Then lactating female MCM/Gsαfl/fl mice were intraperitoneally injected with tamoxifen(TMX,20 mg/mL)for 10 consecutive days from the delivery day,transferring TMX to the young mice through lactation to construct inductive cardiac-specific Gsα-deficient pups.The body weight and survival rate of the pups were subsequently recorded,and the myocardial structural changes were detected using histological staining.Results As compared with the Sham group,the mice in the TAC group showed significantly increased thickness of end-diastolic left ventricular posterior wall(LVPWd)(P<0.01)and end-diastolic interventricular septum(IVSd)(P<0.05),while decreased end-diastolic left ventricular internal diameter(LVIDd)(P<0.05),suggesting the onset of compensatory cardiac hypertrophy.Histopathological analysis indicated greater cross-sectional area of myocardium and higher perivascular fibrosis progression rate(P<0.01),and the mRNA and protein levels of Gsαwere significantly increased in the TAC group(P<0.05).Compared to the control group,the TMX-

关 键 词：主动脉弓缩窄 心肌肥厚 心脏发育 Gsα 他莫昔芬 基因敲除 

分 类 号：R363.21[医药卫生—病理学] R394.3[医药卫生—基础医学]