LncRNA Fendrr: involvement in the protective role of nucleolin against HO-induced injury in cardiomyocytes.

Nucleolin is a multifunctional nucleolar protein with RNA-binding properties. Increased nucleolin expression protects cells from HO-induced damage, but the mechanism remains unknown. Long noncoding RNAs (lncRNAs) play crucial roles in cardiovascular diseases. However, the biological functions and underlying mechanisms of lncRNAs in myocardial injury remain unclear. In a nucleolin-overexpressing cardiac cell line, high-throughput technology was used to identify lncRNAs controlled by nucleolin. Cell counting kit-8 assay was used to determine cell viability, lactate dehydrogenase (LDH) assay to detect cell death, caspase activity assay and propidium iodide staining to confirm cell apoptosis, and RNA immunoprecipitation to examine the interaction between Fendrr and nucleolin. We found that Fendrr expression was significantly downregulated in mouse hearts subjected to myocardial ischemia-reperfusion (MI/R) injury. High Fendrr expression abrogated HO-mediated injury in cardiomyocytes as evidenced by increased cell viability and decreased cell apoptosis. Conversely, Fendrr knockdown exacerbated the cardiomyocytes injury. Also, nucleolin overexpression inhibits Fendrr downregulation in HO-induced cardiomyocyte injury. Fendrr overexpression significantly reversed the role of the suppression of nucleolin expression in HO-induced cardiomyocytes. LncRNA Fendrr is involved in the cardioprotective effect of nucleolin against HO-induced injury and may be a potential therapeutic target for oxidative stress-induced myocardial injury.