MicroRNA mimics that target the placental renin-angiotensin system inhibit trophoblast proliferation.

In early gestation, the human placental renin-angiotensin system (RAS) is upregulated and plays a role in placental development. Among other functions, signalling through the angiotensin II type 1 receptor (AT1R) initiates proliferation. Many microRNAs (miRNAs) targeting placental RAS mRNAs are downregulated at this time. We propose that in early gestation miRNAs that target the placental RAS are downregulated, allowing for the increased RAS expression and proliferation required for adequate placentation. HTR-8/SVneo cells (an immortalized human trophoblast cell line) were used to assess the effect of nine miRNA mimics (at 0.08, 0.16, 0.32 and 0.64 ng/μL) on trophoblast cell proliferation and predicted RAS target mRNAs. The effect of the miRNA mimics on the rate of cell proliferation was assessed using the xCELLigence real-time cell analysis system over 48 h. Levels of miRNAs and predicted RAS target mRNAs were determined by RT-PCR (qPCR, n = 9/group). Statistically different levels of expression were determined (P < 0.05). All nine miRNA mimics significantly affected the proliferation rates of HTR-8/SVneo cells. Five of the miRNA mimics (miR-181a-5p (predicted to target: renin (REN), angiotensin converting enzyme (ACE)), miR-378 (REN, ACE), miR-663 (REN), miR-483-3p (ACE, ACE2, angiotensinogen (AGT), angiotensin II type 1 receptor (AGTR1)) and miR-514 (AGT)) were associated with a dose-dependent reduction in cell proliferation. Seven of the mimics significantly decreased expression of at least one of their predicted target RAS mRNAs. Our study shows that miRNAs targeting placental RAS mRNAs play a role in controlling trophoblast proliferation. As placentation is largely a process of proliferation, changes in expression of these miRNAs may be partly responsible for the expression of the placental RAS, proliferation and placentation.