2025 Volume 66 Issue 5 Pages 862-873
Cardiomyocyte apoptosis is the underlying pathogenic factor of myocardial ischemia-reperfusion injury (MIRI). Long non-coding RNA (lncRNA) non-coding RNA activated by DNA damage (NORAD) plays a crucial role in cell apoptosis regulation. In this study, we investigated the mechanism of lncRNA NORAD in promoting MIRI via the miR-144-3p/trinucleotide repeat-containing gene 6a (TNRC6A) axis.
H9C2 cells were induced by oxygen-glucose deprivation/reperfusion (OGD/R) in vitro, and then treated with oe-NORAD, si-NORAD, miR-144-3p inhibitor, and oe-TNRC6A. Meanwhile, an MIRI rat model was established and treated with sh-NORAD. The expression of NORAD, miR-144-3p, TNRC6A, apoptosis proteins, and inflammatory factors (tumor necrosis factor-α [TNF-α] and interleukin [IL]-6) was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blot, and enzyme-linked immunosorbent assay. Cell viability and apoptosis were assessed using Cell Counting Kit-8 and flow cytometry. Echocardiography, 2,3,5-triphenyltetrazolium chloride staining, hematoxylin-eosin staining, and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining were used to evaluate cardiac function, pathological changes in myocardial tissues, and myocardial apoptosis. Additionally, the potential binding sites of miR-144-3p with NORAD and TNRC6A were predicted using the StarBase database and then validated by the dual-luciferase reporter gene assay.
NORAD expression, cell apoptosis, and TNF-α and IL-6 levels were augmented, whereas miR-144-3p expression and cell viability were diminished in OGD/R-exposed cells. NORAD knockdown impeded OGD/R-induced cardiomyocyte apoptosis and inflammatory responses. Repression of miR-144-3p or TNRC6A overexpression partially offset the inhibitory effect of NORAD knockdown on OGD/R-induced cardiomyocyte apoptosis. In vivo tests confirmed that NORAD knockdown reduced MIRI in rats.
Highly expressed NORAD promoted cardiomyocyte apoptosis and inflammatory responses. However, NORAD knockdown suppressed cardiomyocyte apoptosis to reduce MIRI through the miR-144-3p/TNRC6A axis.
