MicroRNA-214 regulates smooth muscle cell differentiation from stem cells by targeting RNA-binding protein QKI

// Yutao Wu 1, * , Zhoubin Li 2, * , Mei Yang 1 , Bing Dai 1 , Feng Hu 1 , Feng Yang 1 , Jianhua Zhu 1 , Ting Chen 1 , Li Zhang 1 1 Department of Cardiology, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, PR China 2 Department of Lung Transplantation, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, PR China * These authors have contributed equally to this work Correspondence to: Li Zhang, email: li_zhang@zju.edu.cn Ting Chen, email: ting010151452@aliyun.com Keywords: miR-214, Quaking (QKI), stem cells, smooth muscle cells, cell differentiation Received: December 02, 2015     Accepted: November 30, 2016     Published: February 08, 2017 ABSTRACT MicroRNA-214(miR-214) has been recently reported to regulate angiogenesis and embryonic stem cells (ESCs) differentiation. However, very little is known about its functional role in vascular smooth muscle cells (VSMCs) differentiation from ESCs. In the present study, we assessed the hypothesis that miR-214 and its target genes play an important role in VSMCs differentiation. Murine ESCs were seeded on collagen-coated flasks and cultured in differentiation medium for 2 to 8 days to allow VSMCs differentiation. miR-214 was significantly upregulated during VSMCs differentiation. miR-214 overexpression and knockdown in differentiating ESCs significantly promoted and inhibited VSMCs -specific genes expression, respectively. Importantly, miR-214 overexpression in ESCs promoted VSMCs differentiation in vivo . Quaking (QKI) was predicted as one of the major targets of miR-214, which was negatively regulated by miR-214. Luciferase assay showed miR-214 substantially inhibited wild type, but not the mutant version of QKI-3-UTR-luciferase activity in differentiating ESCs, further confirming a negative regulation role of miR-214 in QKI gene expression. Mechanistically, our data showed that miR-214 regulated VSMCs gene expression during VSMCs differentiation from ESCs through suppression of QKI. We further demonstrated that QKI down-regulated the expression of SRF, MEF2C and Myocd through transcriptional repression and direct binding to promoters of the SRF, MEF2c and Myocd genes. Taken together, we have uncovered a central role of miR-214 in ESC-VSMC differentiation, and successfully identified QKI as a functional modulating target in miR-214 mediated VSMCs differentiation.