PPAR-γ激动剂抑制血管紧张素Ⅱ诱导血管平滑肌细胞的表型转化

Peroxisome proliferators-activated receptor-gamma agonist inhibits angiotensin Ⅱ-induced phenotypic switching of vascular smooth muscle cells

目的探讨过氧化物酶体增殖物激活受体(peroxisome proliferator activated receptor gamma,PPAR-γ)激动剂罗格列酮(rosiglitazone,RSG)对血管紧张素Ⅱ(angiotensinⅡ,AngⅡ)诱导小鼠血管平滑肌细胞(vascular smooth muscle cells,VSMCs)表型转化的抑制作用及其可能的机制。方法体外培养小鼠血管平滑肌细胞,应用AngⅡ诱导VSMCs的表型转化,给予罗格列酮预处理后用Transwell检测细胞迁移并在激光共聚焦显微镜下观察细胞微丝骨架,用RT-q PCR和Western blot分别检测PPAR-γ、PKGⅠα以及VSMCs收缩型标志因子(smooth muscle 22 alpha,SM22α)m RNA和蛋白水平。应用PPAR-γ抑制剂预处理后再给予罗格列酮刺激,Western blot检测PKGⅠα和SM22α蛋白水平。结果 1罗格列酮(20μmol/L)预处理可抑制AngⅡ诱导VSMCs的迁移(P<0.05)。2罗格列酮(20μmol/L)预处理后可抑制AngⅡ诱导VSMCs微丝骨架的形成。3RT-q PCR检测结果显示:罗格列酮(20μmol/L)预处理后可抑制AngⅡ诱导PKGⅠα和SM22αm RNA的下调作用(P<0.05)。4Western blot检测结果显示:罗格列酮(20μmol/L)预处理后可抑制AngⅡ诱导PKGⅠα和SM22α蛋白水平的下调作用(P<0.05);PPAR-γ抑制剂GW9662可减弱罗格列酮对PKGⅠα和SM22α的促表达作用(P<0.05)。结论罗格列酮通过激活PPAR-γ来抑制AngⅡ诱导VSMCs的表型转化,激活PPAR-γ可能通上调PKGⅠα表达发挥上述作用。

Objective To investigate the inhibitory effect of peroxisome proliferator-activated receptor-gamma( PPAR-γ) agonist,rosiglitazone( RSG),on the phenotypic switching in vascular smooth muscle cells( VSMCs) induced by angiotensin Ⅱ( Ang Ⅱ). Methods Ang Ⅱ was employed to induce phenotypic switching in cultured mouse VSMCs. After pretreated with RSG and then treated with AngⅡ,the migration of VSMCs was analyzed by Transwell chamber assay,and F-actin polymerization was detected by Phalloidine-i FluorTM488 staining under a laser confocal microscope. The protein and m RNA levels of PPAR-γ,PKGⅠα and smooth muscle 22 alpha( SM22α,a marker molecule in differentiated VSMC with contractile phenotype) were measured by Western blotting and RT-q PCR. Also,Western blotting was employed to detect protein levels of PKGⅠα and SM22α in the VSMCs which were pretreated with PPAR-γ inhibitor,GW9662 before RSG stimulation. Results RSG( 20 μmol/L) pretreatment significantly inhibited Ang Ⅱ-induced VSMCs immigration( P < 0. 05) and formation of actin cytoskeleton. Results from RT-q PCR indicated thatRSG pretreatment also reversed the down-regulation of PKG Ⅰα and SM22α at mR NA and protein levels in Ang Ⅱ-stimulated VSMCs( all P < 0. 05). However,GW9662 treatment could attenuate the up-regulation of PKGⅠ α and SM22α in RSG-treated VSMCs( P < 0. 05). Conclusion RSG inhibits the phenotypic switching of VSMCs from a 'contractile 'to a 'synthetic 'state in response to Ang Ⅱ through activating PPAR-γ,and then up-regulating PKGⅠα.