MicroRNAs (miRNAs) regulate various cardiac processes including cell proliferation and apoptosis. Pioglitazone (PIO), a peroxisome proliferator-activated receptor (PPAR)-γ agonist, protects against myocardial ischaemia–reperfusion (IR) injury. We assessed the effects of PPAR-γ activation on myocardial miRNA levels and the role of miRNAs in IR injury.
Researchers from the University of Texas Medical Branch evaluated the expression changes of miRNAs in the rat heart after PIO administration using LC Sciences’ miRNA arrays and then confirmed the result by northern blot. miR-29a and c levels decreased remarkably after 7-day treatment with PIO. In H9c2 cells, the effects of PIO and rosiglitazone on miR-29 expression levels were blocked by a selective PPAR-γ inhibitor GW9662. Downregulation of miR-29 by antisense inhibitor or by PIO protected H9c2 cells from simulated IR injury, indicated as increased cell survival and decreased caspase-3 activity. In contrast, overexpressing miR-29 promoted apoptosis and completely blocked the protective effect of PIO. Antagomirs against miR-29a or -29c significantly reduced myocardial infarct size and apoptosis in hearts subjected to IR injury. Western blot analyses demonstrated that Mcl-2, an anti-apoptotic Bcl-2 family member, was increased by miR-29 inhibition.
Downregulation of miR-29 protected hearts against IR injury. The modulation of miRNAs can be achieved by pharmacological intervention. These findings provide a rationale for the development of miRNA-based strategies for the attenuation of IR injury.
MiRNA expression changes after administration of PIO (5 mg/kg/days) or water for 7 days (there were three rats in each group)
(A) Log2 values of each PIO/sham pair of miRNA microarray signal were displayed in a heat-map generated by TIGR Multiexperiment Viewer software. Red indicates upregulation; green, downregulation; black, no change. The bar code on the top represents the colour scale of the log2 values. (B) Bar graph indicating the fold change in expression in PIO group compared with the baseline of the miRNAs of interest. (C and D) Northern blot showed the time course effect of PIO on miR-29a and -29c expression levels in rat hearts. (E and F) The densitometry analysis of northern blot. The data represented the average of nine signal values for each miRNA on the array. *P < 0.05 vs. control.
Related Service
miRNA Microarray Service – LC Sciences provides a microRNA (miRNA) expression profiling service using microarrays based on our in-house developed µParaflo® technology platform. We have standard arrays for all mature miRNAs of all species available in the latest version of the miRBase database (Release 21, July 2014). Our service is comprehensive and includes sample labeling, array hybridization, image data processing and in-depth data analysis. Two-three weeks after receiving your total RNA samples, we’ll send you both the raw and fully analyzed data. [Learn more…]
Reference
Ye Y, Hu Z, Lin Y, Zhang C, Perez-Polo JR. (2010) Downregulation of microRNA-29 by antisense inhibitors and a PPAR-{gamma} agonist protects against myocardial ischaemia-reperfusion injury. Cardiovasc Res 87(3), 535-44. [article]