COP1 was a direct target of miR-214.

<p>(A) Schematic diagram of luciferase reporter vectors. The sequence region including the putative binding sites of miR-214 (21–23 and 31–38 in the 3'UTR of <i>COP1</i> mRNA, XM573181.4) was inserted in the pMIR-REPORT Luciferase vector as wild type. Two types of mutant vectors (mutant-1 and mutant 2) are also synthesized as shown in this figure. (B) Luciferase reporter assay for effect of co-transfection with miR-214 on luciferase activity in Ud6 cells. miR-214 was able to repress the luciferase activity of Ud6 cells transfected with the wild-type vector although it failed to show repression when mutant-1 and mutant-2 vectors were used for the co-transfection, indicating that miR-214 directly targeted <i>COP1</i> mRNA through binding to the predicted seed sequences in 3'UTR of <i>COP1</i> mRNA. All data are present as the mean of triplicate experiments with error bars indicating the s.d. (Two-tailed t-test; *p<0.05, **p<0.01). (C) Effect of transfection of HSA cell lines and normal EC with miR-214 on <i>COP1</i> mRNA expressions in them, assessed by qRT-PCR. <i>COP1</i> mRNA expression was down-regulated dose-dependently by miR-214-transfection. <i>TBP</i> was used for the normalization of each mRNA expressions. All data are expressed as the mean of triplicate experiments with error bars indicating the s.d. (Two-tailed t-test; *p<0.05, **p<0.01). (D) Expression level of COP1 protein in HSA cell lines and normal EC transfected with miR-214. COP1 protein expression was also dose-dependently down-regulated in the HSA cell lines transfected with miR-214. (E) Effect of miR-214-knockdown in control EC. Knockdown of miR-214 up-regulated COP1 expression in control EC.