Li Jun, He Xijing, Wei Wenzhi, Zhou Xiaobo
Department of Emergency, Shannxi Province People's Hospital, Third Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710052, China.
Department of Orthopaedics, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China.
Biochem Biophys Res Commun. 2015 May 1;460(2):482-8. doi: 10.1016/j.bbrc.2015.03.059. Epub 2015 Mar 19.
Osteoblast differentiation is a vital process in maintaining bone homeostasis in which various transcriptional factors, signaling molecules, and microRNAs (miRNAs) are involved. Recently, signal transducer and activator of transcription 1 (STAT1) has been found to play an important role in regulating osteoblast differentiation. Here, we identified that STAT1 expression was regulated by miR-194. Using mouse bone mesenchymal stem cells (BMSCs), we found that miR-194 expression was significantly increased following osteoblast differentiation induction. Overexpression of miR-194 by lentivirus-mediated gene transfer markedly increased osteoblast differentiation, whereas inhibition of miR-194 significantly suppressed osteoblast differentiation of BMSCs. Using a dual-luciferase reporter assay, a direct interaction between miR-194 and the 3'-untranslated region (UTR) of STAT1 was confirmed. Additionally, miR-194 regulated mRNA and protein expression of STAT1 in BMSCs. Further analysis showed that miR-194 overexpression promoted the nuclear translocation of runt-related transcription factor 2 (Runx2), which is critical for osteoblast differentiation. In contrast, inhibition of miR-194 blocked the nuclear translocation of Runx2. Moreover, overexpression of STAT1 significantly blocked Runx2 nuclear translocation and osteoblast differentiation mediated by miR-194 overexpression. Taken together, our data suggest that miR-194 regulates osteoblast differentiation through modulating STAT1-mediated Runx2 nuclear translocation.
成骨细胞分化是维持骨稳态的一个重要过程，涉及多种转录因子、信号分子和微小RNA（miRNA）。最近，人们发现信号转导子和转录激活子1（STAT1）在调节成骨细胞分化中发挥重要作用。在此，我们确定STAT1的表达受miR-194调控。利用小鼠骨髓间充质干细胞（BMSC），我们发现成骨细胞分化诱导后miR-194表达显著增加。通过慢病毒介导的基因转移过表达miR-194可显著增加成骨细胞分化，而抑制miR-194则显著抑制BMSC的成骨细胞分化。采用双荧光素酶报告基因检测法，证实了miR-194与STAT1的3'-非翻译区（UTR）之间存在直接相互作用。此外，miR-194调节BMSC中STAT1的mRNA和蛋白表达。进一步分析表明，miR-194过表达促进了对成骨细胞分化至关重要的 runt相关转录因子2（Runx2）的核转位。相反，抑制miR-194可阻断Runx2的核转位。此外，STAT1过表达显著阻断了miR-194过表达介导的Runx2核转位和成骨细胞分化。综上所述，我们的数据表明miR-194通过调节STAT1介导的Runx2核转位来调节成骨细胞分化。
