细胞外信号调节激酶1／2途径参与甲状旁腺素1-34诱导的心肌细胞肥大

Parathyroid hormone 1-34 induce cardiac myocytes hypertrophy via extracellular regulated protein klnase 1/2 pathway

目的观察丝裂素活化蛋白激酶的上游激酶1（MAPKK，MEK1）抑制剂PD98059对大鼠甲状旁腺素1.34（rPTH1-34）诱导的心室肌细胞肥大的影响及细胞外信号调节激酶1／2（ERK1／2）表达的变化，分析MEK／ERK途径的可能作用。方法体外培养新生大鼠心室肌细胞，10^-7mol／L rPTH1-34诱导建立心肌细胞肥大模型，在模型中加入2×10^-5mol／L PD98059，Motic Images Advanced3．0软件测定细胞直径、^3H-亮氨酸掺入实验检测细胞蛋白合成速率、RT-PCR半定量测定心房利钠肽mRNA、Western blot方法观察ERK1／2、磷酸化ERK1／2蛋白表达的变化。结果与正常组相比，10^-7mol／L rPTH1-34孵育24h可使体外培养的心肌细胞直径增加13.6μm、细胞蛋白合成速率增加898cpm／well，使心房利钠肽mRNA表达增加73．9％，p-ERK1／2蛋白表达增加15％（P〈0．05）。与PTH组相比，预先给予PD98059可使细胞直径减少7.1μm，细胞蛋白合成速率减少644cpm／well，心房利钠肽mRNA表达下降52．2％，磷酸化ERK1／2蛋白表达减少18％（P〈0．05）。单独使用PD98059对正常心肌细胞没有影响（P〉0．05）。结论PD98059通过抑制ERK1／2、磷酸化ERK1／2的表达阻断了心肌细胞肥大反应，MEK／ERK1／2途径的活化参与了rPTH1-34的致肥大作用。

Objective To investigate the role of mitogen activated protein kinase kinase 1 （MAPKK, MEK1 ） and regulated kinasel/2 （ERK1/2） on cardiac hypertrophy induced by rat parathyroid hormone1-34 （rPTH1-34）. Method Neonatal rat cardiomyocytes was treated with or without 10^-7moL/L rPTH1-34 in the absence or presence 2×10^-5moL/L PD98059, a MEK1 inhibitor. Cellular diameter was measured by Motic Images Advanced 3.0 software and the synthetic rate of protein in cardiac myocytes was detected by ^3H-leucine incorporation, mRNA expression of atrial natriuretic peptide （ANP） was measured by RT-PCR and protein expression of ERK1/2 and p-ERK1/2 was measured by Western blot. Results rPTH1-34 （10^-7mol/L） significantly increase cellular diameter （＋13.6μm）, ^3H-leucine incorporation （＋898 cpm/well）, ANP mRNA expression （ ＋73.9% ）, and p-ERK1/2 protein expression （ ＋ 15% ） compared to control cells （ all P 〈 0. 05 ） and these effects could be significantly attenuated by PD98059 ： cellular diameter （ -7.1μm ）, ^3H-leucine incorporation （ -644 cpm/well ）, ANP mRNA expression （ - 52.2% ）, and protein expression of p-ERK1/2 （ - 18% ） （ all P 〈 0.05 vs. PTH group）. PD98059 did not affect control cells without PTH treatment （ all P 〉 0. 05 ）. Conclusions PD98059 attenuates PTH induced cardiac hypertrophy in vitro via inhibiting the expression of ERK1/2 and p-ERK1/2.