The long noncoding RNA NR_045363 involves cardiomyocyte apoptosis and cardiac repair via p53 signal pathway.

Long noncoding RNAs (lncRNAs) can participate in various biological behaviors, including regulating cell differentiation, proliferation, and apoptosis. The investigators have previously confirmed that highly conserved lncRNA NR_045363 controls cardiomyocyte (CM) proliferation and cardiac repair. The present study investigates the effects of NR_045363 on CM apoptosis. Seven-day-old mice were subjected to permanent left anterior descending coronary artery ligation (LAD), and the NR_045363 expression was analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The expression of NR_045363 in the MI group significantly exceeded the Sham group during the first week after the operation. The NR_045363 expression was knocked down in primary cultured CMs using an NR_045363-targeting lncRNA Smart silencer, and the apoptosis of CMs was analyzed by terminal-deoxynucleoitidyl transferase mediated nick end labeling and Annexin-V/PI double staining. These present results indicate that the NR_045363 knockdown significantly promoted the apoptosis of CMs. In order to investigate the underlying mechanism, RNA-sequencing (RNA-seq) was performed, and ingenuity pathway analysis (IPA) was used to analyze the RNA-seq results. The RNA-seq data revealed that a total of 2,291 genes were upregulated or downregulated in NR_045363 knockdown CMs, and the IPA analysis indicated that tumor protein 53 (p53) was the upstream regulator. In vivo, the NR_045363 overexpression through the AAV9 system improved the heart function after MI in 7-day-old mice and inhibited the CM apoptosis. These data suggest that NR_045363 is involved in CM apoptosis and that NR_045363 overexpression exerts positive effects on cardiac repair by alleviating CM apoptosis through the inhibition of the p53 pathway.