LncRNA-6395 promotes myocardial ischemia-reperfusion injury in mice through increasing p53 pathway

Crosstalk among Reactive Oxygen Species, Autophagy and Metabolism in Myocardial Ischemia and Reperfusion Stages

Myocardial ischemia is the most common cardiovascular disease. Reperfusion, an important myocardial ischemia tool, causes unexpected and irreversible damage to cardiomyocytes, resulting in myocardial ischemia/reperfusion (MI/R) injury. Upon stress, especially oxidative stress induced by reactive oxygen species (ROS), autophagy, which degrades the intracellular energy storage to produce metabolites that are recycled into metabolic pathways to buffer metabolic stress, is initiated during myocardial ischemia and MI/R injury. Excellent cardioprotective effects of autophagy regulators against MI and MI/R have been reported. Reversing disordered cardiac metabolism induced by ROS also exhibits cardioprotective action in patients with myocardial ischemia. Herein, we review current knowledge on the crosstalk between ROS, cardiac autophagy, and metabolism in myocardial ischemia and MI/R. Finally, we discuss the possible regulators of autophagy and metabolism that can be exploited to harness the therapeutic potential of cardiac metabolism and autophagy in the diagnosis and treatment of myocardial ischemia and MI/R.

lncRNA CCAT2 Protects Against Cardiomyocyte Injury After Myocardial Ischemia/Reperfusion by Regulating BMI1 Expression

Myocardial ischemia/reperfusion (I/R) decreases cardiac function and efficiency. Accumulating evidence suggests that long noncoding RNAs (lncRNAs) have been linked to the cellular processes of myocardial I/R injury. The present investigation elucidated the function of lncRNA colon cancer-associated transcript 2 (CCAT2) in myocardial I/R injury and the related mechanisms.AC16 cardiomyocytes were exposed to hypoxia (16 hours) /reoxygenation (6 hours) (H/R) to mimic myocardial I/R models in vitro. CCAT2 and microRNA (miR) -539-3p expressions in AC16 cardiomyocytes were measured using real-time quantitative polymerase chain reaction. B-cell-specific Moloney murine leukemia virus insertion region 1 (BMI1) protein levels in AC16 cardiomyocytes were determined by western blotting. Cell viability, lactate dehydrogenase (LDH) leakage, reactive oxygen species (ROS) levels, mitochondrial membrane potential, and apoptosis were detected using Counting Kit-8, LDH Assay Kit, dihydroethidium assay, 5,5',6,6'-tetrachloro1,1',3,3'-tetramethylbenzimidazolylcarbocyanine iodide staining, flow cytometry, and western blotting, respectively. The interactions between the molecules were confirmed using the dual-luciferase gene reporter. The wingless/integrated/beta-catenin (Wnt/β-catenin) pathway under the H/R condition was detected by western blotting.CCAT2 and BMI1 mRNA expressions were reduced in H/R-exposed AC16 cardiomyocytes. CCAT2 overexpression exerted protective effects against H/R-induced cardiomyocyte injury, as demonstrated by increased cell viability and mitochondrial membrane potential and decreased LDH leakage, ROS levels, and apoptosis. In addition, CCAT2 positively regulated BMI1 expression by binding to miR-539-3p. CCAT2 knockdown or miR-539-3p overexpression restrained the protective effects of BMI1 against H/R-induced cardiomyocyte injury. In addition, miR-539-3p overexpression reversed the protective effects of CCAT2. Furthermore, CCAT2 activated the Wnt/β-catenin pathway under the H/R condition via the miR-539-3p/BMI1 axis.Overall, this investigation showed the protective effects of the CCAT2/miR-539-3p/BMI1/Wnt/β-catenin regulatory axis against cardiomyocyte injury induced by H/R.

Lnc-PXMP4-2-4 alleviates myocardial cell damage by activating the JAK2/STAT3 signaling pathway

PURPOSE

The aim of this study was to investigate the protective effect of long non-coding lnc-PXMP4-2-4 on myocardial cell damage caused by acute myocardial infarction (AMI).

METHODS

Peripheral blood mononuclear cells (PBMC) were collected from 24 patients with AMI on the day of admission, the first day after percutaneous coronary intervention (PCI) and the third day after surgery, and 24 patients with clinical control group. Real-time quantitative PCR(QRT-PCR) was used to detect the expression of related genes. Then in human cardiomyocytes (AC16), Cell Counting Kit-8 (CCK-8) was used to determine cell viability, lactate dehydrogenase release assay (LDH) was used to determine the release of lactate dehydrogenase, PCR was used to detect the expression of genes, cell death was detected by flow cytometry, and the expression of related proteins was measured by Western blot. The effect of lnc-PXMP4-2-4 was further studied by silencing and overexpressing lnc-PXMP4-2-4.

RESULTS

Compared with clinical control group, the expression of lnc-PXMP4-2-4 in PBMC of AMI patients was significantly higher than it. Compared with pre-operation, the expression of lnc-PXMP4-2-4 was significantly up-regulated on day 1 after PCI, and recovered to pre-operation level on day 3 after surgery. In AC16 cells, lnc-PXMP4-2-4 inhibited the proliferation of AC16, promoted the release of LDH and increased cell death, aggravated the cardiomyocyte injury caused by H2O2, and inhibited the expression of JAK2 and STAT3 mRNA and protein. The up-regulation of lnc-PXMP-4-2-4 had the opposite effect. In addition, the inhibition of the signal pathway by JAK2/STAT3 pathway inhibitor AG490 partially weakened the enhanced viability of AC16 cells, decreased LDH release and apoptosis induced by lnc-PXMP4-2-4 overexpression, increased Bcl-2 expression and down-regulated Bax expression.

CONCLUSION

Therefore, we conclude that lnc-PXMP4-2-4 protects cardiomyocytes from injury by activating the JAK2/STAT3 signaling pathway.

The Role of P53 in Myocardial Ischemia-Reperfusion Injury

PURPOSE

P53 is one of the key tumor suppressors. In normal cells, p53 is maintained at low levels by the ubiquitination of the ubiquitinated ligase MDM2. In contrast, under stress conditions such as DNA damage and ischemia, the interaction between p53 and MDM2 is blocked and activated by phosphorylation and acetylation, thereby mediating the trans-activation of p53 through its target genes to regulate a variety of cellular responses. Previous studies have shown that the expression of p53 is negligible in normal myocardium, tends to increase in myocardial ischemia and is maximally induced in ischemia-reperfused myocardium, demonstrating a possible key role of p53 in the development of MIRI. In this review, we detail and summarize recent studies on the mechanism of action of p53 in MIRI and describe the therapeutic agents targeting the relevant targets to provide new strategies for the prevention and treatment of MIRI.

METHODS

We collected 161 relevant papers mainly from Pubmed and Web of Science (search terms "p53" and "myocardial ischemia-reperfusion injury"). After that, we selected pathway studies related to p53 and classified them according to their contents. We eventually analyzed and summarized them.

RESULTS AND CONCLUSION

In this review, we detail and summarize recent studies on the mechanism of action of p53 in MIRI and validate its status as an important intermediate affecting MIRI. On the one hand, p53 is regulated and modified by multiple factors, especially non-coding RNAs; on the other hand, p53 regulates apoptosis, programmed necrosis, autophagy, iron death and oxidative stress in MIRI through multiple pathways. More importantly, several studies have reported medications targeting p53-related therapeutic targets. These medications are expected to be effective options for the alleviation of MIRI, but further safety and clinical studies are needed to convert them into clinical applications.

Long Noncoding RNAs Involved in Cardiomyocyte Apoptosis Triggered by Different Stressors

Cardiomyocytes are essential to maintain the normal cardiac function. Ischemia, hypoxia, and drug stimulation can induce pathological apoptosis of cardiomyocytes which eventually leads to heart failure, arrhythmia, and other cardiovascular diseases. Understanding the molecular mechanisms that regulate cardiomyocyte apoptosis is of great significance for the prevention and treatment of cardiovascular diseases. In recent years, more and more evidences reveal that long noncoding RNAs (lncRNAs) play important regulatory roles in myocardial cell apoptosis. They can modulate the expression of apoptosis-related genes at post-transcriptional level by altering the translation efficacy of target mRNAs or functioning as a precursor for miRNAs or competing for miRNA-mediated inhibition. Moreover, reversing the abnormal expression of lncRNAs can attenuate and even reverse the pathological apoptosis of cardiomyocytes. Therefore, apoptosis-related lncRNAs may become a potential new field for studying cardiomyocyte apoptosis and provide new ideas for the treatment of cardiovascular diseases.