STAT3介导了血小板源性生长因子BB诱导的大鼠血管平滑肌细胞Pim-1表达

STAT3 mediates PDGF-BB-induced Pim-1 expression in rat vascular smooth muscle cells

目的:观察血小板源性生长因子BB(PDGF-BB)是否可以诱导大鼠血管平滑肌细胞(VSMCs)表达Pim-1及Pim-1对VSMCs增殖的影响,探讨STAT3信号分子在这一过程中的作用,为血管重建性疾病(VRD)的研究提供实验依据。方法:不同浓度PDGF-BB作用不同时间刺激体外培养的VSMCs,用细胞计数法检测增殖;用re-al-time RT-PCR检测Pim-1 mRNA表达水平;Western blotting检测STAT3的活性变化;用放线菌素D(actinomycinD)、AG490(JAK特异性抑制剂)及siRNA沉默Pim-1和STAT3进行干预。结果:PDGF-BB(20μg/L)作用VSMCs24 h,可以诱导细胞增殖,Pim-1沉默抑制了这一过程;正常未经处理的VSMCs Pim-1 mRNA表达量较低,不同浓度PDGF-BB(10μg/L～50μg/L)作用VSMCs 1 h,Pim-1 mRNA表达明显增加,其中以20μg/L最显著;用PDGF-BB(20μg/L)作用VSMCs不同时间(0.5 h～4 h),可显著上调Pim-1 mRNA表达,以0.5 h最显著。用actinomycin D及AG490预处理后Pim-1 mRNA表达随之降低。PDGF-BB可激活VSMCs中磷酸化STAT3水平,AG490和转染STAT3-siRNA可抑制STAT3的磷酸化以及相应的Pim-1 mRNA表达。结论:PDGF-BB可通过Pim-1调节VSMCs增殖;STAT3可能参与了PDGF-BB诱导的VSMCs Pim-1表达。

AIM： To study the expression of Pim-1 in vascular smooth muscle cells （VSMCs） induced by platelet-derived growth factor BB （PDGF-BB）. METHODS： VSMCs isolated from rats were treated with different concen- trations of PDGF-BB for different time. The proliferation of VSMCs was detected by cell counting. The mRNA expression of Pim-1 was measured by real-time RT-PCR. The STAT3 activity was determined by Western blotting. Actinomycin D, AG490, and small interfering RNA （siRNA） for Pim-1 or STAT3 were used to investigate the underlying mechanisms. RE- SULTS： Pim-1 gene silencing attenuated the proliferation of VSMCs in response to PDGF-BB. The mRNA expression of Pim-1. was up-regulated by PDGF-BB at concentrations of 10 μg/L-50 μg/L for 1 h, and was maximally induced at the concentration of 20 μg/L. The time of Pim-1 mRNA expression maximally occurred 30 min after PDGF-BB exposure. Incu- bation of VSMCs with PDGF-BB resulted in a significant activation of STAT3. VSMCs pretreated with actinomycin D showed a significant decrease in the mRNA expression of Pim-1. Treatment with AG490 or knockdown of STAT3 in VSMCs resulted in inactivation of STAT3, and significantly suppressed the mRNA expression of Pim-1. CONCLUSION： PDGF- BB-indueed VSMC proliferation is partly attributed to Pim-1. VSMCs strongly increase Pim-1 mRNA upon stimulation with PDGF-BB, and STAT3 signaling pathway appears to be efficient for regulation of Pim-1 expression. This process may play a critical role in development of vascular remodeling.