3.5 miR-26a suppresses ECM deposition by directly targeting
CTGF.
CTGF is essential for the synthesis of collagen (Liang et al. ,
2014). We hypothesized that miR-26a attenuates ECM accumulation by
regulating CTGF. In vivo data shown in Figure 5a support this
hypothesis: CTGF protein level was significantly downregulated in SHR
thoracic aortas with rAAV-miR-26a overexpression. The effect of miR-26a
was further confirmed in vitro: miR-26a mimic suppressed CTGF expression
in AngII-induced VSMCs and miR-26a inhibitor increased CTGF protein and
mRNA levels in vitro (Fig. 5b, c). Bioinformatics analysis by using
Targetscan (www.targetscan.org) predicted CTGF as a potential target
gene of miR-26a (Fig. 5d). By using a reporter construct with the
putative 3′-UTR miR-26a binding site of CTGF downstream of the
luciferase gene, we found that miR-26a reduced luciferase activity,
which provides experimental validation of CTGF as a target for miR-26a.
Accordingly, after mutation of the binding site, the activity of
luciferase was not altered (Fig. 5e), which confirms that the binding of
miR-26a to the 3′-UTR site was necessary for silencing CTGF