经典Wnt/β-catenin/TCF7L2信号通路在1型糖尿病心肌病中的作用

Effect of activated canonical Wnt/β-catenin/TCF7L2 signaling pathway in type 1 diabetic cardiomyopathy

目的 探讨Wnt/β-catenin/TCF7L2信号通路在1型糖尿病小鼠心肌病中的作用。方法利用7~8周龄♂C57BL/6小鼠腹腔注射链脲佐菌素,建立1型糖尿病模型,糖尿病小鼠成模4周后,随机分为糖尿病组、β-catenin通路抑制剂iCRT14(2.5、5 mg·kg^-1)组。连续腹腔给药8周后,HE染色检测心脏细胞形态;免疫组化及Western blot检测β-catenin、TCF7L2蛋白表达;荧光定量PCR检测β-catenin、Tcf7l2、Nppa、c-Myc mRNA表达。结果糖尿病组心肌细胞排列相对紊乱、细胞核大小不规则;Western blot和免疫组化结果显示,糖尿病组小鼠心脏β-catenin、TCF7L2表达升高,心肌细胞核内β-catenin、TCF7L2表达明显增多;qPCR显示,β-catenin/TCF7L2通路下游基因c-Myc、心肌肥大基因Nppa表达上调。iCRT14组小鼠心肌细胞排列相对规则,形态趋于正常;β-catenin、TCF7L2蛋白表达降低,核内表达减少;肥大基因Nppa、下游基因c-Myc mRNA表达明显减低。结论 Wnt/β-catenin/TCF7L2通路活化在糖尿病心肌病发生、发展中发挥重要作用,β-catenin抑制剂能明显减缓1型糖尿病小鼠心肌病的进程。

Aim To determine the role of Wnt/β-catenin/TCF7L2 pathway in diabetic cardiomyopathy.Methods A model of type 1 diabetes mellitus was established by intraperitoneal injection of streptozotocin(STZ) into 7 or 8-week old C57BL/6 mice.After four weeks,the diabetic animals were divided into three groups with seven to eight in each:diabetes mellitus(DM),diabetes injected with β-catenin inhibitor iCRT14(2.5,5 mg·kg^-1).After continuous intrap- eritoneal administration for 8 weeks,heart samples were stained with HE and examined under light microscopy.Expressions and distributions of β-catenin and TCF7L2 in myocardium were detected by immunohistochemistry.Protein levels of β-catenin,Tcf7l2 were detected by Western blot.mRNA levels of β-catenin,Tcf7l2,Nppa and c-Myc were detected by qPCR.Results The myocardial cells in DM were relatively disordered and the size of the nucleus was irregular.Western blot and immunohistochemistry data showed that the expressions of β-catenin and TCF7L2 in heart with DM increased,while those in nucleus of the cardiomyocytes significantly increased.qPCR showed that the mRNA expression of β-catenin downstream target c-Myc and cardiac hypertrophy marker Nppa were up-regulated.After injection of eight weeks with different iCRT14 doses,the cardiomyocytes were relatively regular;the protein levels of β-catenin and TCF7L2 decreased,and their expressions in nucleus decreased as well;the mRNA levels of Nppa and c-Myc markedly decreased.Conclusions Activation of canonical Wnt/β-catenin/TCF7L2 signaling pathway plays a pivotal role in diabetic cardiomyopathy;iCRT14 significantly improves the phenotype of cardiomyopathy in type 1 diabetic mice.