Figure 4. PTEN 3’UTR and KRAS1P 3’UTR function as decoys and a general model for endogenous microRNA decoy mechanism.

a. PTENP1 mRNA level 24h after the transfection of the empty pCMV or pCMV/PTEN3’UTR plasmid in DU145 cells (left) and growth curve (right). b. KRAS mRNA level 24h after the transfection of the empty pCMV or pCMV/K1P3’UTR plasmid in DU145 cells (left) and growth curve (right). c. Model. X and Y are different transcripts targeted by the same microRNA(s). In the steady state (middle), equilibrium exists between the microRNA molecules and their targets X and Y. Downregulation of X (left) leads to increased availability of microRNA molecules to bind to Y, thus decreasing its abundance. By contrast, overexpression of X (right) leads to less microRNA molecules free to bind to Y, and thus Y abundance increases. Red rectangles: microRNA molecules. X and Y can be a pseudogene and its cognate protein-coding gene. a and b. mean ± s.d., n ≥ 3.