Figure 3. Downregulation of SMAD7, SPRY1 and PTEN by high glucose is mediated by miR-21. Perindopril-treated ARPE-19 cells were transfected with scramble control (NG and high glucose), miR-21 mimic (high glucose), or antagomir of miR-21 (high glucose). Compared to NG, quantitative real-time PCR (qRT-PCR) showed high glucose-mediated suppression of SMAD7, SPRY1, and PTEN. In addition, miR-21 mimics under the high glucose condition further reduced the transcript level of SMAD7 and SPRY1 compared with high glucose alone. However, blocking miR-21 by its antagomir significantly increased the expression of SMAD7, SPRY1, and PTEN. mRNA levels were expressed relative to HPRT, and NG was set to 1. Mean ± standard error of the mean (SEM); n = 4. *p<0.05, **p<0.001 versus NG; #p<0.001 versus high glucose, high glucose and miR-21 mimics; ¶ p<0.05 (SMAD7) or p<0.001 (SPRY1) versus high glucose.