Song Lan, Zhou Fangliang, Cheng Lijuan, Hu Mei, He Yingchun, Zhang Bo, Liao Duanfang, Xu Zhaojun
Department of Biochemistry and Molecular Biology, Hunan University of Chinese Medicine, 300 Xueshi Road, Hanpu Science and Teaching Park, Changsha, Hunan, 410208, China.
Division of Stem Cell Regulation and Application, State Key Laboratory of Chinese Medicine Powder and Medicine Innovation in Hunan (Incubation), Hunan University of Chinese Medicine, 300 Xueshi Road, Hanpu Science and Teaching Park, Changsha, Hunan, 410208, China.
Inflammation. 2017 Jun;40(3):927-936. doi: 10.1007/s10753-017-0537-1.
Excessive autophagic activity of alveolar type II epithelial (AT-II) cells is one of the main causes of acute lung injury (ALI); however, the underlying molecular mechanism remains to be determined. The microRNAs (miRNAs) are involved with autophagy in many diseases. The objective of this study was therefore to investigate the relationship between the miRNA expression and the autophagic activity of the AT-II cells in the pathogenesis of ALI and its molecular mechanism. A mouse model of ALI and AT-II cell injury was induced using lipopolysaccharide (LPS) in vivo and in vitro, and the expression of miR-34a and the autophagy-related proteins LC3 II/I and p62 were determined. Moreover, the autophagic activity was investigated after miR-34a overexpression and inhibition. The effects of miR-34a on its target gene, FoxO3, in regulating autophagic activity in AT-II cells were also determined. LPS induced autophagic activity and increased the expression of miR-34a in lung tissues and in AT-II cells. The in vitro results showed that the upregulation of miR-34a suppressed, whereas the inhibition of miR-34a promoted, autophagy in AT-II cells. Moreover, miR-34a could directly bind to the 3'-untranslated region of the autophagy-related gene, FoxO3, to decrease its expression. In addition, the knockdown of FoxO3 expression inhibited the autophagic activity in AT-II cells. Together, this study suggested that miR-34a might suppress the excessive autophagic activity in AT-II cells via targeting FoxO3 to reduce the damage of LPS-induced ALI.
肺泡Ⅱ型上皮(AT-II)细胞的自噬活性过度是急性肺损伤(ALI)的主要原因之一;然而,其潜在的分子机制仍有待确定。微小RNA(miRNA)在许多疾病中都与自噬有关。因此,本研究的目的是探讨ALI发病机制中miRNA表达与AT-II细胞自噬活性之间的关系及其分子机制。采用脂多糖(LPS)在体内和体外诱导建立ALI和AT-II细胞损伤的小鼠模型,检测miR-34a以及自噬相关蛋白LC3 II/I和p62的表达。此外,在miR-34a过表达和抑制后研究自噬活性。还确定了miR-34a对其靶基因FoxO3在调节AT-II细胞自噬活性中的作用。LPS诱导肺组织和AT-II细胞的自噬活性并增加miR-34a的表达。体外实验结果表明,miR-34a上调抑制而抑制miR-34a则促进AT-II细胞的自噬。此外,miR-34a可直接结合自噬相关基因FoxO3的3'-非翻译区以降低其表达。此外,敲低FoxO3表达可抑制AT-II细胞的自噬活性。总之,本研究表明miR-34a可能通过靶向FoxO3抑制AT-II细胞中过度的自噬活性,以减轻LPS诱导的ALI损伤。