甲状腺功能亢进激活心肌细胞β-catenin/FoxO1诱导大鼠心室重构的作用

Hyperthyroidism Induces Ventricular Remodeling via Activatingβ-catenin/FoxO 1 in Rat Cardiomyocytes

【目的】探究甲亢激活心肌细胞β-catenin/FoxO1诱导大鼠心室重构的作用和机制。【方法】通过甲状腺激素(T40.1 mg/kg/day;腹腔注射)连续给药30 d构建甲亢诱导心室重构大鼠体内模型。利用β-catenin抑制剂MSAB(14 mg/kg)同时给药30 d,通过Western-blot检测心肌肥厚主要标志物ANP以及β-catenin、FoxO1等蛋白的表达情况;免疫荧光检测β-catenin、FoxO1的核内外表达及分布情况。利用原代培养的乳鼠心肌细胞,使用甲状腺激素(T320 nmol/L)处理心肌细胞24 h构建体外甲亢诱导心肌细胞肥厚模型,利用β-cateninsiRNA(30 nmol/L)转染心肌细胞敲低β-catenin,Western-blot和免疫荧光检测抑制β-catenin对甲亢诱导乳鼠心肌细胞肥厚的影响。【结果】Wnt/β-catenin通路激活后β-catenin入核增多并于细胞核内的转录因子结合发挥转录调控作用。β-catenin在甲亢诱导的大鼠心室重构模型心肌细胞核内表达显著增加,而其经典下游转录因子TCF7l2表达无显著差异。我们的结果显示,MSAB抑制β-catenin明显改善甲亢诱导的大鼠心室重构。进一步研究表明甲亢诱导大鼠心肌肥厚过程中心肌细胞β-catenin/FoxO1表达明显增强,抑制心肌细胞β-catenin/FoxO1改善甲亢诱导大鼠心肌肥厚。【结论】甲亢性心肌肥厚心肌细胞β-catenin/FoxO1活化,抑制β-catenin/FoxO1改善甲状腺激素诱导的心肌细胞肥大。

【Objective】To explore how hyperthyroidism induces ventricular remodeling via activatingβ-catenin/FoxO1 in rat cardiomyocytes.【Methods】Hyperthyroidism-induced ventricular remodeling rat models were established by intraperitoneal injection of levothyroxine(T4)at 0.1 mg/kg for 30 days.β-catenin inhibitor MSAB(14 mg/kg)was admin-istrated for 30 days.We used western blot to detect the expression of myocardial hypertrophy marker ANP,β-catenin and FoxO1;immunofluorescence to examine the expression and intracellular distribution ofβ-catenin and FoxO1.Hyperthy-roidism-induced cardiomyocyte hypertrophy rat models were established by treatment of triiodothyronine(T3)into cul-tured primary neonatal rat cardiomyocytes for 24 hours.β-catenin siRNA(30 nmol/L)was used to down-regulateβ-catenin expression in cardiomyocytes.Western blot and immunofluorescence were used to analyze the effects ofβ-catenin inhibition on the hyperthyroidism-induced cardiomyocyte hypertrophy.【Results】Following Wnt/β-catenin activation,β-catenin was found increased nuclear expression,to bind to the nuclear transcriptional factors and regulate the gene ex-pression.β-catenin nuclear expression was significantly increased in the hyperthyroidism-induced ventricular remodeling rats,but no change was found in the expression of typical transcriptional factor TCF7l2.Our results revealed that inhibitingβ-catenin by MSAB attenuated the hyperthyroidism-induced rat ventricular remodeling.Further analysis indicated thatβ-catenin/FoxO1 expression was significantly increased in hyperthyroidism-induced myocardial hypertrophy which could be attenuated by suppressingβ-catenin/FoxO1 in cardiomyocytes.【Conclusions】β-catenin/FoxO1 is activated in hyperthy-roidism-induced myocardial hypertrophy andβ-catenin/FoxO1 inhibition attenuates hyperthyroidism-induced cardiomyo-cyte hypertrophy.