降钙素基因相关肽对血管平滑肌细胞心肌素表达及细胞表型改变的作用

Effect of calcitonin gene-related peptide on myocardin expression and phenotypic switch in vascular smooth muscle cells

目的:研究降钙素基因相关肽(CGRP)对血管平滑肌细胞(VSMCs)心肌素表达的影响及对细胞表型改变的调节作用。方法:取大鼠胸主动脉,以组织块贴壁培养法获得VSMCs,分为对照组、血管紧张素Ⅱ(AngⅡ)组(加入AngⅡ处理)、CGRP组(加入AngⅡ和CGRP处理)和CGRP8-37组(在AngⅡ和CGRP基础上加入CGRP8-37)。Western blot法检测VSMCs中心肌素及细胞表型标志蛋白α-平滑肌肌动蛋白(α-SMA)和骨桥蛋白(OPN)表达情况。结果:在VSMCs培养中,细胞心肌素表达水平随着培养时间延长逐渐降低,细胞培养48 h和72h时心肌素表达水平较基线水平显著降低(P<0.05);而加入CGRP处理后,心肌素表达水平逐渐增加,与基线水平比较,加入CGRP培养后48 h和72 h时细胞心肌素水平显著增加(P<0.05)。同时,在VSMCs培养48 h时,AngⅡ组细胞心肌素水平较对照组下降(P<0.05),且α-SMA表达亦相应下降(P<0.05),而OPN表达水平显著增加(P<0.05);CGRP组VSMCs心肌素水平较AngⅡ组增加,伴随着α-SMA表达水平增加(P<0.05),相反地OPN表达水平下降(P<0.05);CGRP8-37组心肌素和α-SMA表达水平较CGRP+AngⅡ组降低(P<0.05),而OPN表达较CGRP组增加(P<0.05)。结论:CGRP通过促进VSMCs心肌素的表达而抑制细胞表型转换,使细胞维持收缩表型,且这一作用是CGRP通过与其受体结合后实现的。

AIM： To investigate the effects of calcitonin gene-related peptide（ CGRP） on myocardin expression and phenotypic switch in vascular smooth muscle cells（ VSMCs）. METHODS： VSMCs were obtained by aortic tissue adherent culture and treated with angiotensin Ⅱ（ AngⅡ）,AngⅡ ＋ CGRP or AngⅡ ＋ CGRP ＋ CGRP8-37. The protein expression of myocardin and the phenotypic proteins of the VSMCs was detected by Western blot. RESULTS： The expression of myocardin in cultured VSMCs showed downregulation along with time expansion. The protein level of myocardin was higher at 48 h and 72 h than that at baseline in the cultured VSMCs（P〈0. 05）. However,the myocardin was lower at 48 h and 72 h than that at baseline after treatment with CGRP in cultured VSMCs（P〈0. 05）. Furthermore,at 48 h in cultured VSMCs,the myocardin decreased along with α-smooth muscle actin（ α-SMA）（P〈0. 05）,and osteopontin（ OPN）increased（P〈0. 05） in AngⅡ group compared with control group. After treatment with CGRP,the levels of myocardin and α-SMA become higher（P〈0. 05） but OPN was lower（P〈0. 05） in CGRP group than those in Ang Ⅱ group.CGRP8-37 abrogated CGRP-induced increase in myocardin and α-SMA and decrease in OPN in CGRP8-37 group compared with CGRP group. CONCLUSION： CGRP may regulate the phenotypic switch of the VSMCs and maintain the cells in contractile phenotype through the upregulation of myocardin protein,which may be accomplished by the combination of CGRP and its receptor.