LncRNA RP11-400K9.4 Aggravates Cardiomyocytes Apoptosis After Hypoxia/Reperfusion Injury by Targeting miR-423

Spatial Multiplexed Protein Profiling of Cardiac Ischemia-Reperfusion Injury

BACKGROUND

Reperfusion therapy is critical to myocardial salvage in the event of a myocardial infarction but is complicated by ischemia-reperfusion injury (IRI). Limited understanding of the spatial organization of cardiac cells, which governs cellular interaction and function, has hindered the search for targeted interventions minimizing the deleterious effects of IRI.

METHODS

We used imaging mass cytometry to characterize the spatial distribution and dynamics of cell phenotypes and communities in the mouse left ventricle following IRI. Heart sections were collected from 12 cardiac segments (basal, mid-cavity, apical, and apex of the anterior, lateral, and inferior wall) and 8 time points (before ischemia [I-0H], and postreperfusion [R-0H, R-2H, R-6H, R-12H, R-1D, R-3D, R-7D]), and stained with 29 metal-isotope-tagged antibodies. Cell community analysis was performed on reconstructed images, and the most disease-relevant cell type and target protein were selected for intervention of IRI.

RESULTS

We obtained a total of 251 multiplexed images, and identified 197 063 single cells, which were grouped into 23 distinct cell communities based on the structure of cellular neighborhoods. The cellular architecture was heterogeneous throughout the ventricular wall and exhibited swift changes following IRI. Analysis of proteins with posttranslational modifications in single cells unveiled 13 posttranslational modification intensity clusters and highlighted increased H3K9me3 (tri-methylated lysine 9 of histone H3) as a key regulatory response in endothelial cells during the middle stage of IRI. Erasing H3K9 methylation, by silencing its methyltransferase Suv39h1 or overexpressing its demethylase Kdm4d in isolated endothelial cells, attenuated cardiac dysfunction and pathological remodeling following IRI. in vitro, H3K9me3 binding significantly increased at endothelial cell function-related genes upon hypoxia, suppressing tube formation, which was rescued by inhibiting H3K9me3.

CONCLUSIONS

We mapped the spatiotemporal heterogeneity of cellular phenotypes in the adult heart upon IRI, and uncovered H3K9me3 in endothelial cells as a potential therapeutic target for alleviating pathological remodeling of the heart following myocardial IRI.

Metallothionein-2A Protects Cardiomyocytes from Hypoxia/reper-Fusion through Inhibiting p38

The reperfusion of coronary artery blood supply is often accompanied by myocardial hypoxia/reperfusion (H/R) injury, and induced cardiomyocytes apoptosis. The activation of p38 can induce apoptosis, thereby aggravating the myocardial H/R injury. Metallothionein-2A (MT2A) has the functions of anti-apoptosis and protective effect through p38. However, it is not clear that MT2A may protect cardiomyocytes from H/R injury through p38 signaling pathway. Here, we constructed an H/R model for H9c2 cardiomyocytes to explore the protective effect of MT2A on cardiomyocytes apoptosis during the process of H/R through p38 signal pathway. The results revealed that both endogenously overexpressed MT2A and exogenously added MT2A can inhibit the active expression of p-p38 and cleaved caspase-3 under H/R. Based on our results, H/R induced cardiomyocytes apoptosis and activation of p38. And, MT2A can inhibit the active expression of caspase-3 and p38. We found that MT2A can protect cardiomyocytes apoptosis from H/R injury through p38 signaling pathway.

miR-15b-5p REGULATES THE NLRP3 INFLAMMASOME SIGNAL THROUGH TARGETING SIRT3 TO REGULATE HYPOXIA/REOXYGENATION-INDUCED CARDIOMYOCYTE PYROPTOSIS PROCESS

ABSTRACT

Hypoxia/reoxygenation (H/R) induces pyroptosis in the setting of acute myocardial infarction (AMI). Previous studies have shown that the expression of the miR-15 family is stimulated in myocardial ischemia-reperfusion injury or H/R-induced cardiomyocyte injury, and miR-15 is a promoter of cardiac ischemia-reperfusion or H/R injury. However, whether miR-15b-5p regulates H/R injury and cardiomyocyte pyroptosis and its mechanism still need to be further clarified. Bioinformatics analysis elicited that SIRT3 was the downstream regulatory target gene of miR-15b-5p. SIRT3 has been shown to participate in the regulation of pyroptosis by negatively regulating the NLRP3 inflammasome pathway. Therefore, we hypothesized that miR-15b-5p targets SIRT3 and activated the NLRP3 inflammasome pathway to promote H/R-induced cardiomyocyte pyroptosis. We first show that H/R increases miR-15b-5p in rat cardiomyocytes H9C2. Next, we tested the effects of inhibition of miR-15b-5p or overexpression of SIRT3. We found that miR-15b-5p downregulation or SIRT3 overexpression could reverse the H/R-induced pyroptosis. Furthermore, silencing SIRT3 antagonized the protective effect of miR-15b-5p downregulation on H9C2 cells. NLRP3 inhibitor MCC950 annulled the previously mentioned antagonistic effect of silencing SIRT3 on the protection of miR-15b-5p downregulation against pyroptosis. We then used a rat AMI model to analyze myocardial infarction area by triphenyl tetrazolium chloride staining and assess serum cardiac troponin T level by ELISA and found that miR-15b-5p silencing reduced AMI injury in rats. Collectively, these results suggest that miR-15b-5p increase H/R-induced pyroptosis in cardiomyocytes by targeting SIRT3 and activating the NLRP3 inflammasome.

RNA sequencing reveals novel LncRNA/mRNAs co-expression network associated with puerarin-mediated inhibition of cardiac hypertrophy in mice

Background

Evidence has demonstrated that puerarin is a potential medicine for the treatment of cardiac hypertrophy. However, the precise underlying molecular mechanisms of the protective effect of puerarin are still unclear. Here, we aimed to explore the regulatory mechanisms of lncRNAs/mRNAs co-expression network in a cardiac hypertrophy mouse model after puerarin treatment.

Methods

A mouse model of cardiac hypertrophy was established by transverse aortic constriction (TAC). The echocardiography, tissue staining and western blot were used to examine the protective effect of puerarin. Then RNA sequencing (RNA-seq) was carried out to analyze systematically mRNAs and lncRNAs expression. The target lncRNA were confirmed using qRT-PCR. Moreover, a coding/non-coding gene co-expression network were established to find the interaction of lncRNA and mRNAs. The biological process, cellular component, molecular function and pathways of different expression mRNAs targeted by lncRNA were explored using Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis.

Results

Puerarin exhibited an obvious inhibitory effect in cardiac hypertrophy in TAC model. RNA-seq analysis was performed to investigate the lncRNAs and mRNAs expression patterns of cardiomyocytes in sham and TAC groups treated with or without puerarin. RNA-seq identified that TAC downregulated four lncRNAs, which could be revised by puerarin treatment (|log2 Fold change| > 2 and FDR < 0.05). Among them, expression alterations of lncRNA Airn (antisense of Igf2r non-protein coding RNA) was confirmed by qRT-PCR. Pearson's correlation coefficients of co-expression levels suggested that there was an interactive relationship between Airn and 2,387 mRNAs (r > 0.95 or r < -0.95). Those co-expressed mRNAs were enriched in some important biological processes such as translational initiation, cell proliferation, insulin-like growth factor binding and poly(A) RNA binding. KEGG analyses suggested that those Airn-interacted mRNAs were enriched in endocytosis, signaling pathways regulating pluripotency of stem cells and the Jak-STAT pathway.

Conclusion

Puerarin may exert beneficial effects on cardiac hypertrophy through regulating the lncRNAs/mRNAs co-expression network.