MiR-145-5p promotes myocardial cell apoptosis in rats with myocardial infarction through PI3K/Akt signaling pathway

LncRNA XR_595552 inhibition alleviates intermittent hypoxia-induced cardiomyocyte damage via activating the PI3K/AKT pathway

BACKGROUND

Although the long noncoding RNAs (lncRNAs) expression profiles have been observed in previous study, the biological functions and underlying mechanisms of lncRNAs in OSA-related cardiac injury have not been elucidated. In the present study, we investigated a novel lncRNA, lncRNA XR_595552, and evaluated its role in intermittent hypoxia (IH)-induced damage in H9c2 cardiomyocytes.

METHODS

H9c2 cells were exposed to IH condition. Real-time quantitative polymerase chain reaction (RT-qPCR) was conducted to measure the expression changes of lncRNA XR_595552 in H9c2 cells stimulated by IH. H9c2 cells were subjected to IH after transfection. CCK-8 was used to evaluate cell viability, and apoptosis was analyzed by Western blotting. Additionally, the regulatory relationship between lncRNA XR_595552 and PI3K/AKT was tested by RT-qPCR and Western blot.

RESULTS

IH significantly induced injury in H9c2 cells (inhibited cell viability and promoted cell apoptosis). lncRNA XR_595552 was upregulated in a cell model of IH. Inhibition of lncRNA XR_595552 protected H9c2 cells against IH-induced damage, as the viability was increased, Bax, Caspase-9, and Caspase-3 were downregulated, and Bcl-2 was upregulated. More interestingly, lncRNA XR_595552 downregulation activated the PI3K/AKT pathway. Blocking the PI3K/AKT signal pathway by the use of LY294002 eliminated the myocardioprotective effects of lncRNA XR_595552 in H9c2 cells under IH condition.

CONCLUSIONS

The results show that lncRNA XR_595552, a novel lncRNA, may play a protective role in attenuating IH-induced injury in cardiomyocytes via a regulating PI3K/AKT pathway. The findings suggest that this lncRNA could serve as a therapeutic target to treat OSA-related cardiovascular disorders.

Candidate genes and their alternative splicing may be potential biomarkers of acute myocardial infarction: a study of mouse model

Background

Acute myocardial infarction (AMI) is one of the leading causes of death in human being, and an effective diagnostic biomarker is still lacking. Whilst some gene association with AMI has been identified by RNA sequencing (RNA-seq), the relationship between alternative splicing and AMI is not clear.

Methods

We retrieved myocardial tissues within 24 h from mice with induced AMI and sham, and analysed the differentially expressed genes (DEGs) and differential alternative splicing genes (DASGs) by RNA-seq. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and protein interaction network analysis were performed on DEGs-DASGs-overlap genes. PCR was used to verify the expression levels of representative genes and alternative splicing in myocardial tissues of AMI and sham mice.

Results

1367 DEGs were identified, including 242 up-regulated and 1125 down-regulated genes, among which there were 42 DASGs. GO analysis showed that the cellular component was primarily enriched in plasma membrane, cell membrane integrity and extracellular region. The molecular function was enriched in protein binding and metal ion binding. The biological process was primarily enriched in cell adhesion, immune system process and cell differentiation. KEGG analysis showed the enrichment was mainly in JAK-STAT and PI3K-AKT signalling pathway. Postn, Fhl1, and Fn1 were low-expressed while Postn alternative splicing was high-expressed in myocardial tissue of AMI mice, which was consistent with sequencing results.

Conclusions

The pathogenesis of AMI involves differentially expressed genes and differential alternative splicing. These differentially expressed genes and their alternative splicing, especially, Fhl1, Fn1 and Postn may become new biomarkers of AMI.

Elevated mir-145-5p is associated with skeletal muscle dysfunction and triggers apoptotic cell death in C2C12 myotubes

Skeletal muscle dysfunction is a common comorbidity of chronic obstructive pulmonary disease (COPD), and the molecular mechanisms regarding to the pathogenesis of this disease have not been elucidated. In this study, a novel miR-145-5p was significantly upregulated in the serum collected from patients with COPD-associated muscle atrophy, in contrast with the normal participants. Then, we evidenced that silencing of miR-145-5p suppressed cell death and elongated cell survival during cell culture process. Consistently, upregulation of miR-145-5p induced cell apoptosis and restrain cell viability in the C2C12 cells, suggesting that miR-145-5p contributes to cell death. Further experiments evidenced that miR-145-5p decreased the expression levels of phosphorylated PI3K (p-PI3K), Akt (p-Akt) and mTOR (p-mTOR) to inactivate the PI3K/Akt/mTOR pathway, and this pathway was also reactivated by miR-145-5p ablation. Finally, we proved that the protective effects of miR-145-5p ablation were abrogated by co-treating cells with PI3K inhibitor LY294002. Taken together, we concluded that miR-145-5p promoted cell death to facilitate muscle dysfunctions via inactivating the PI3K/Akt/mTOR pathway.

Modulation of miR-145-5p and miR-146b-5p levels is linked to reduced parasite load in H9C2 Trypanosoma cruzi infected cardiomyoblasts

In the heart tissue of acutely Trypanosoma cruzi-infected mice miR-145-5p and miR-146b-5p are, respectively, downregulated and upregulated. Here, we used the H9C2 rat cardiomyoblast cell line infected with the Colombian T. cruzi strain to investigate the parasite-host cell interplay, focusing on the regulation of miR-145-5p and miR-146b-5p expression. Next, we explored the effects of interventions with the trypanosomicidal drug Benznidazole (Bz) alone or combined with Pentoxifylline (PTX), a methylxanthine derivative shown to modulate immunological and cardiac abnormalities in a model of chronic chagasic cardiomyopathy, on parasite load and expression of miR-145-5p and miR-146b-5p. The infection of H9C2 cells with trypomastigote forms allowed parasite cycle with intracellular forms multiplication and trypomastigote release. After 48 and 144 h of infection, upregulation of miR-145-5p (24 h: 2.38 ± 0.26; 48 h: 3.15 ± 0.9-fold change) and miR-146b-5b (24 h: 2.60 ± 0.46; 48 h: 2.97 ± 0.23-fold change) was detected. The peak of both miRNA levels paralleled with release of trypomastigote forms. Addition of 3 µM and 10 µM of Bz 48 h after infection reduced parasite load but did not interfere with miR-145-5p and miR-146b-5p levels. Addition of PTX did not interfere with Bz-induced parasite control efficacy. Conversely, combined Bz + PTX treatment decreased the levels of both microRNAs, resembling the expression levels detected in non-infected H9C2 cells. Moreover, the use of miR-145-5p and miR-146b-5p mimic/inhibitor systems before infection of H9C2 cells decreased parasite load, 72 h postinfection. When H9C2 cells were treated with miR-145-5p and miR-146b-5p mimic/inhibitor 48 h after infection, all the used systems, except the miR-146b-5p inhibitor, reduced parasite load. Altogether, our data indicate that these microRNAs putatively control signaling pathways crucial for parasite–host cell interaction. Thus, miR-145-5p and miR-146b-5p deserve to be further investigated as biomarkers of parasite control and tools to identify therapeutic adjuvants to etiological treatment in Chagas disease.

Targeting Epigenetics and Non-coding RNAs in Myocardial Infarction: From Mechanisms to Therapeutics

Myocardial infarction (MI) is a complicated pathology triggered by numerous environmental and genetic factors. Understanding the effect of epigenetic regulation mechanisms on the cardiovascular disease would advance the field and promote prophylactic methods targeting epigenetic mechanisms. Genetic screening guides individualised MI therapies and surveillance. The present review reported the latest development on the epigenetic regulation of MI in terms of DNA methylation, histone modifications, and microRNA-dependent MI mechanisms and the novel therapies based on epigenetics.

Differentially expressed TUG1 and miR-145-5p indicate different severity of chronic heart failure and predict 2-year survival prognosis

Long non-coding RNAs (lncRNAs) and microRNAs (miRs) have critical roles in the progression of various diseases. The present study aimed to investigate the levels and clinical significance of lncRNA taurine upregulated gene 1 (TUG1) and miR-145-5p in patients with chronic heart failure (CHF) and explore their indicative value regarding disease severity. TUG1 and miR-145-5p levels were detected by reverse-transcription quantitative PCR. Correlations were examined using Pearson's correlation analysis. Receiver operating characteristic analysis was used to evaluate the diagnostic value of TUG1, miR-145-5p and brain natriuretic peptide (BNP). Survival analysis was performed by the Kaplan-Meier method. Cox regression analysis was used to evaluate the prognostic value of TUG1 and miR-145-5p. The levels of interleukin-6 and tumor necrosis factor-α in serum were detected by ELISA. The results indicated that TUG1 was upregulated and miR-145-5p was downregulated in patients with CHF and they were negatively correlated. TUG1 and miR-145-5p were associated with the left ventricle ejection fraction and were able to indicate the severity of CHF. Serum TUG1 and miR-145-5p had a certain diagnostic value and the combination of BNP, TUG1 and miR-145-5p had high diagnostic accuracy. TUG1 and miR-145-5p were closely associated with overall survival and may function as independent prognostic biomarkers for patients with CHF. In addition, TUG1 and miR-145-5p levels were markedly correlated with inflammation in CHF. Upregulated TUG1 and downregulated miR-145-5p may indicate the severity of CHF, may serve as diagnostic and prognostic biomarkers and may be involved in CHF progression by regulating inflammatory responses.