A novel long noncoding RNA FAF inhibits apoptosis via upregulating FGF9 through PI3K/AKT signaling pathway in ischemia–hypoxia cardiomyocytes

Abstract Long noncoding RNAs (lncRNAs) have been increasingly considered to play an important role in the pathological process of various cardiovascular diseases, which often bind to the proximal promoters of the protein‐coding gene to regulate the protein expression. However, the functions and mechanisms of lncRNAs in cardiomyocytes have not been fully elucidated. High‐throughput RNA sequencing was performed to identify the differently expressed lncRNAs and messenger RNAs (mRNAs) between acute myocardial infarction (AMI) rats and healthy controls. One novel lncRNA FGF9‐associated factor (termed FAF) and mRNAs in AMI rats were verified by bioinformatics, real‐time polymerase chain reaction or western blot. Moreover, RNA fluorescence in situ hybridization was performed to determine the location of lncRNA. Subsequently, a series of in vitro assays were used to observe the functions of lncRNA FAF in cardiomyocytes. The expression of lncRNA FAF and FGF9 were remarkably decreased in ischemia–hypoxia cardiomyocytes and heart tissues of AMI rats. Overexpression of FAF could significantly inhibit cardiomyocytes apoptosis induced by ischemia and hypoxia. Conversely, knockdown of lncRNA FAF could promote apoptosis in ischemia–hypoxia cardiomyocytes. Moreover, overexpression of lncRNA FAF could also increase the expression of FGF9. Knockdown of the FGF9 expression could promote apoptosis in cardiomyocytes with the insult of ischemia and hypoxia, which was consistent with the effect of lncRNA FAF overexpression on cardiomyocyte apoptosis. Mechanistically, FGF9 inhibited cardiomyocytes apoptosis through activating signaling tyrosine kinase FGFR2 via phosphoinositide 3‐kinase/protein kinase B signaling pathway. Thus, lncRNA FAF plays a protective role in ischemia–hypoxia cardiomyocytes and may serve as a treatment target for AMI.