Luciferase reporter assay
For transfections, host H9C2 cells were plated in triplicate into 24-well plates containing Lipofectamine 2000 (Invitrogen, Carlsbad, USA) and 0.8 μg pEZX-miR-210 (or pEZX-miR-Sc) per well. The precursor miR-210 expression clone was established via a feline immunodeficiency virus using the lentiviral vector system (pEZX-miR-210). Subsequently, we designed the luciferase reporter targeting the 3-UTR of Caspase8ap2 to surround the binding sites of miR-210. The Dual-Luciferase Reporter Assay System kit (Promega, Madison, USA) was used to measure the amount of luciferase and Renilla luciferase activity with a fluorescence spectrophotometer. The relative transcriptional activity was normalized to its corresponding value.