Liu Yun, Sun Xiuzhen, Wu Yuanyuan, Fang Ping, Shi Hongyang, Xu Jing, Li Manxiang
Department of Respiratory Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University Medical College, 157 Xiwu Road, Xi'an Shaanxi, 710004, China.
Mol Cell Biochem. 2015 Nov;409(1-2):135-43. doi: 10.1007/s11010-015-2519-7. Epub 2015 Jul 22.
The pathological changes of airway smooth muscle (ASM) contribute to airway remodeling during asthma. Here, we investigated the effect of miR-145 on ASM function. We found that miR-145 was aberrantly more highly expressed in ASM cells exposed to cytokine stimulation that mimic the airway conditions of patients with asthma. Repression of miR-145 resulted in decreased ASM cell proliferation and migration in a dose-dependent manner and down-regulation of type I collagen and contractile protein MHC in ASM cells. qRT-PCR and Western blot analysis demonstrated that miR-145 negatively regulated the expression of downstream target Krüppel-like factor 4 (KLF4) protein, and overexpression of KLF4 attenuated the effects of miR-145 on ASM cells. Further studies showed that KLF4 significantly up-regulated the expression of p21 and down-regulated matrix metalloproteinase (MMP-2 and MMP-9). In conclusion, miR-145 overexpression in ASM cells significantly inhibited KLF4, and subsequently affected downstream p21, MMP-2, and MMP-9 expressions, eventually leading to enhanced proliferation and migration of ASM cells in vitro.
气道平滑肌（ASM）的病理变化在哮喘期间会导致气道重塑。在此，我们研究了miR-145对ASM功能的影响。我们发现，在模拟哮喘患者气道状况的细胞因子刺激下，ASM细胞中miR-145异常高表达。抑制miR-145会导致ASM细胞增殖和迁移呈剂量依赖性降低，以及ASM细胞中I型胶原蛋白和收缩蛋白MHC的下调。qRT-PCR和蛋白质印迹分析表明，miR-145负向调节下游靶标Krüppel样因子4（KLF4）蛋白的表达，而KLF4的过表达减弱了miR-145对ASM细胞的影响。进一步研究表明，KLF4显著上调p21的表达并下调基质金属蛋白酶（MMP-2和MMP-9）。总之，ASM细胞中miR-145的过表达显著抑制KLF4，并随后影响下游p21、MMP-2和MMP-9的表达，最终导致体外ASM细胞增殖和迁移增强。
