Long noncoding Mirt2 reduces apoptosis to alleviate myocardial infarction through regulation of the miR-764/PDK1 axis



Acute myocardial infarction (AMI) is a common clinical cardiovascular disease, which is the leading cause of death and disability worldwide. Abnormal expression of long noncoding RNAs (lncRNA) is reported to be related to myocardial dysfunctions such as myocardial infarction (MI). In this study, we aimed to investigate the role of lncRNA myocardial infarction-related transcription factors 2 (Mirt2) in AMI and the underlying molecular mechanisms in vivo and in vitro. In vivo AMI model was established by occlusion of the left anterior descending coronary artery. Rats were randomly divided into two groups (five rats per group): the sham group and the AMI group. H9c2 cells were cultured under hypoxia for 4 h and then cultured under normoxia to establish the in vitro hypoxia reoxygenation (H/R) model. Our study shows that the myocardial infarct size and the apoptosis in AMI rats were both significantly increased, indicating that the AMI rat model was successfully established. Additionally, the levels of Mirt2 in AMI rats were increased significantly. Knockdown of Mirt2 by shRNA (shMirt2) had no significant effect on apoptosis and MI in sham rats, but significantly promoted apoptosis and MI in AMI rats. In vitro experiments showed that shMirt2 significantly decreased the level of Mirt2 in H9c2 cells and H9c2 cells treated with H/R. It is worth noting that shMirt2 had no significant effect on H9c2 cells, but significantly increased the levels of oxidative stress markers (malondialdehyde and lactate dehydrogenase), and also increased the number of apoptosis of H/R-treated H9c2 cells. Further mechanistic analysis showed that Mirt2 could protect MI and apoptosis in AMI rats by competitively adsorbing miR-764 and reducing the inhibitory effect of miR-764 on 3-phosphoinositide-dependent kinase 1 (PDK1). More importantly, after overexpression of Mirt2, MI and apoptosis were significantly improved in AMI rats, indicating that Mirt2 showed a protective effect in AMI rats. In summary, these findings suggest that that Mirt2 participated in the regulation of MI through the miR-764/PDK1 axis. Therefore, the current findings provide a theoretical basis for the diagnosis and treatment of clinical MI with changes in Mirt2 levels.

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Fig. 1: The expression of Mirt2 in rat model of AMI is upregulated.
Fig. 2: Knockdown of Mirt2 promoted ischemia-induced myocardial infarction.
Fig. 3: Knockdown of Mirt2 exacerbated H/R-induced cardiomyocyte injury.
Fig. 4: Mirt2 negatively regulated miR-764 expression as a molecular sponge.
Fig. 5: Mirt2 upregulated PDK1 expression by adsorbing miR-764.
Fig. 6: Mirt2 regulated H/R-induced cardiomyocyte injury through PDK1.
Fig. 7: Mirt2 overexpression showed protective effect in AMI rats.

Data availability

All data generated or analyzed during this study are included in this published article.


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FZ and QL designed the study, supervised the data collection, and analyzed the data; JL interpreted the data and prepare the paper for publication; BL and DL supervised the data collection, analyzed the data, and reviewed the draft of the paper. All authors have read and approved the paper.

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Correspondence to Fen Zhu.

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Animal experiments were undertaken according to the guide for the care and use of National Institutes of Health and approved by the Ethics Committee of Wuhan Third Hospital (Tongren Hospital of Wuhan University).

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Zhu, F., Li, Q., Li, J. et al. Long noncoding Mirt2 reduces apoptosis to alleviate myocardial infarction through regulation of the miR-764/PDK1 axis. Lab Invest (2020). https://doi.org/10.1038/s41374-020-00504-2

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