LncRNA PVT1 Mediated by ZFP36L2 Regulates Myocardial Ischemia/Reperfusion Injury and Attenuates Mitochondrial Fusion and Fission via Activating miR-21-5p/MARCH5 Axis

Background: Among several leading cardiovascular disorders, ischemia-reperfusion (I/R) injury causes severe manifestations including acute heart failure, inflammation, and systemic dysfunction. Recently, there has been increasing evidence suggesting that alterations in mitochondrial morphology play a role in the prognoses of cardiac disorders. Long non-coding RNAs (lncRNAs) form major regulatory networks to modify gene transcription and translation. While several roles of lncRNAs have been explored in cancer and tumor biology, their implications on mitochondrial morphology and functions remain to be elucidated. MethodsThe functional roles of ZFP36L2 and lncRNA PVT1 were determined by a series of cardiomyocyte hypoxia/ reoxygenation (H/R) in vitro and myocardial I/R injury in vivo experiments. Quantitative Reverse transcription-polymerase chain reaction (qRT-PCR) and western blot analysis were used to detect the mRNA levels of ZFP36L2 and mitochondrial fission and fusion markers in the myocardial tissues and cardiomyocyte. Cardiac function was determined by immunohistochemistry, H&E, Masson’s staining and echocardiogram. Ultrastructural analysis of mitochondrial fission was performed using transmission electron microscopy (TEM). The mechanistic model of PVT1 with ZFP36L2 and miR-21-5p with MARCH5 was detected by subcellular fraction, RNA pull down, FISH, and luciferase reporter assays.ResultsIn this study, we report a novel regulatory axis involving lncRNA PVT1, microRNA miR-21-5p, and E3 ubiquitin ligase MARCH5, which alters mitochondrial morphology during myocardial I/R injury. Using an in vivo I/R injury mouse model and in vitro cardiomyocyte H/R model, we observed that zinc finger protein ZFP36L2 directly associated with PVT1 and altered mitochondrial fission and fusion. PVT1 also interacted with miR-21-5p and suppressed its expression and activity. Furthermore, we identified MARCH5 as a modifier of miR-21-5p, and expression of MARCH5 and its effect on mitochondrial fission and fusion were directly proportional to PVT1 expression during H/R injury. ConclusionsOur findings demonstrated that manipulation of PVT1-miR-21-5p-MARCH5-mediated mitochondrial fission and fusion via ZFP36L2 may be a novel therapeutic approach to regulate myocardial I/R injury.