Differentially expressed lncRNAs, miRNAs and mRNAs with associated ceRNA networks in a mouse model of myocardial ischemia/reperfusion injury

Posttranscriptional Regulation by Proteins and Noncoding RNAs

Posttranscriptional regulation comprises those mechanisms occurring after the initial copy of the DNA sequence is transcribed into an intermediate RNA molecule (i.e., messenger RNA) until such a molecule is used as a template to generate a protein. A subset of these posttranscriptional regulatory mechanisms essentially are destined to process the immature mRNA toward its mature form, conferring the adequate mRNA stability, providing the means for pertinent introns excision, and controlling mRNA turnover rate and quality control check. An additional layer of complexity is added in certain cases, since discrete nucleotide modifications in the mature RNA molecule are added by RNA editing, a process that provides large mature mRNA diversity. Moreover, a number of posttranscriptional regulatory mechanisms occur in a cell- and tissue-specific manner, such as alternative splicing and noncoding RNA-mediated regulation. In this chapter, we will briefly summarize current state-of-the-art knowledge of general posttranscriptional mechanisms, while major emphases will be devoted to those tissue-specific posttranscriptional modifications that impact on cardiac development and congenital heart disease.

Integrated Bioinformatics and Validation of lncRNA-Mediated ceRNA Network in Myocardial Ischemia/Reperfusion Injury

Background

Myocardial ischemia/reperfusion (MI/R) injury is a common pathology in ischemia heart disease. Long noncoding RNAs (lncRNAs) are significant regulators related to many ischemia/reperfusion conditions. This study is aimed at exploring the molecule mechanism of lncRNA-mediated competing endogenous RNA (ceRNA) network in MI/R.

Methods

The dataset profiles of MI/R and normal tissues (GSE130217 and GSE124176) were obtained from the GEO database. Integrated bioinformatics were performed to screen out differentially expressed genes (DEGs). Thereafter, an lncRNA-mediated ceRNA network was constructed by the starBase database. The GO annotations and KEGG pathway analysis were conducted to study action mechanism and related pathways of DEGs in MI/R. A model of hypoxia/reoxygenation- (H/R-) treated HL-1 cell was performed to verify the expression of lncRNAs through qRT-PCR.

Results

2406 differentially expressed- (DE-) mRNAs, 70 DE-lncRNAs, and 156 DE-miRNAs were acquired. These DEGs were conducted to construct an lncRNA-mediated ceRNA network, and a subnetwork including lncRNA Xist/miRNA-133c/mRNA (Slc30a9) was screen out. The functional enrichment analyses revealed that the lncRNAs involved in the ceRNA network might functions in oxidative stress and calcium signaling pathway. The lncRNA Xist expression is reduced under H/R conditions, followed by the increased level of miRNA-133c, thus downregulating the expression of Slc30a9.

Conclusion

In sum, the identified ceRNA network which included the lncRNA Xist/miR-133c/Slc30a9 axis might contribute a better understanding to the pathogenesis and development of MI/R injury and offer a novel targeted therapy way.

Regulation of Oxidative Stress by Long Non-coding RNAs in Central Nervous System Disorders

Central nervous system (CNS) disorders, such as ischemic stroke, Alzheimer’s disease, Parkinson’s disease, spinal cord injury, glioma, and epilepsy, involve oxidative stress and neuronal apoptosis, often leading to long-term disability or death. Emerging studies suggest that oxidative stress may induce epigenetic modifications that contribute to CNS disorders. Non-coding RNAs are epigenetic regulators involved in CNS disorders and have attracted extensive attention. Long non-coding RNAs (lncRNAs) are non-coding RNAs more than 200 nucleotides long and have no protein-coding function. However, these molecules exert regulatory functions at the transcriptional, post-transcriptional, and epigenetic levels. However, the major role of lncRNAs in the pathophysiology of CNS disorders, especially related to oxidative stress, remains unclear. Here, we review the molecular functions of lncRNAs in oxidative stress and highlight lncRNAs that exert positive or negative roles in oxidation/antioxidant systems. This review provides novel insights into the therapeutic potential of lncRNAs that mediate oxidative stress in CNS disorders.

MiR-1224 downregulation inhibits OGD/R-induced hippocampal neuron apoptosis through targeting Ku protein

Ischemic cerebrovascular disease is the main cause of disability due to stroke. This study aimed to investigate the function of miR-1224 in OGD/R-induced hippocampal neuron apoptosis, as well as the regulatory mechanism of miR-1224 in ischemic cerebrovascular disease. The oxygen-glucose deprivation/reperfusion (OGD/R) model of primary mouse hippocampal neurons was established. RT-qPCR detected miR-1224, Ku70 and Ku86 levels. Western blotting was applied to measure the expression of Ku70/86 and apoptosis related proteins. Flow cytometry was used to assess apoptosis. JC-1 fluorescence was performed to test the mitochondrial membrane potential (MMP) in neurons. The double luciferase reporter assay was performed to investigate the relationship between miR-1224 and Ku70/86. OGD/R induced the apoptosis and mitochondrial injury in neuronal cells, while miR-1224 downregulation or Ku70/86 upregulation reversed this phenomenon. Meanwhile, miR-1224 negatively regulated the expression of Ku70/86 in neuronal cells through directly targeting Ku70/86. Furthermore, knockdown of Ku70/86 significantly reversed the inhibitory effect of miR-1224 silencing on apoptosis and mitochondrial injury in OGD/R-treated neuronal cells. Our findings indicated that miR-1224 downregulation suppressed OGD/R-induced hippocampal neuron apoptosis by targeting Ku protein, suggesting that miR-1224 could serve as a new target for ischemic cerebrovascular disease treatment.

Bioinformatics-Based Analysis of the lncRNA-miRNA-mRNA Network and TF Regulatory Network to Explore the Regulation Mechanism in Spinal Cord Ischemia/Reperfusion Injury

Background

Spinal cord ischemia/reperfusion injury (SCII) is a catastrophic complication involved with cardiovascular, spine, and thoracic surgeries and can lead to paraplegia. Nevertheless, the molecular mechanism of SCII remain ill-defined.

Methods

Expression profiling (GSE138966) data were obtained from GEO database. Then, differentially expressed (DE) lncRNAs and DEmRNAs were screened out with p < 0.05, and | fold change| > 1.5. Aberrant miRNAs expression in SCII was obtained from PubMed. Functional enrichment analysis of overlapping DEmRNAs between predicted mRNAs in miRDB database and DEmRNAs obtained from GSE138966 was performed using cluster Profiler R package. The lncRNA-miRNA-mRNA competitive endogenous RNA (ceRNA) network was established in light of ceRNA theory. The key lncRNAs in the ceRNA network were identified by topological analysis. Subsequently, key lncRNAs related ceRNA-pathway network and transcription factors (TFs)-mRNAs network were constructed. Simultaneously, the expression levels of hub genes were measured via qRT-PCR.

Results

The results in this study indicated that 76 miRNAs, 1373 lncRNAs, and 4813 mRNAs were differentially expressed in SCII. A SCII-related ceRNA network was constructed with 154 ncRNAs, 139 mRNAs, and 51 miRNAs. According topological analysis, six lncRNAs (NONRATT019236.2, NONRATT009530.2, NONRATT026999.2, TCONS_00032391, NONRATT023112.2, and NONRATT021956.2) were selected to establish the ceRNA-pathway network, and then two candidate hub lncRNAs (NONRATT009530.2 and NONRATT026999.2) were identified. Subsequently, two lncRNA-miRNA-mRNA regulatory axes were identified. NONRATT026999.2 and NONRATT009530.2 might involve SCII via miR-20b-5p/Map3k8 axis based on the complex ceRNA network. SP1 and Hnf4a acting as important TFs might regulate Map3k8. Furthermore, qRT-PCR results showed that the NONRATT009530.2, NONRATT026999.2, Map3k8, Hfn4a, and SP1 were significantly upregulated in SCII of rats, while the miR-20b-5p was downregulated.

Conclusion

Our results offer a new insight to understand the ceRNA regulation mechanism in SCII and identify highlighted lncRNA-miRNA-mRNA axes and two key TFs as potential targets for prevention and treatment of SCII.

Upregulation of miR-144-3p protects myocardial function from ischemia-reperfusion injury through inhibition of TMEM16A Ca2+-activated chloride channel

Myocardial ischemia/reperfusion injury (MIRI) is a major cause of acute cardiac injury that is associated with high morbidity and mortality, and for which specific treatments are lacking. In this study, we investigated the underlying molecular mechanism of miR-144-3p in the pathological process of MIRI. A mouse I/R injury model and H9c2 cardiomyocyte hypoxia/reoxygenation (H/R) model were used to simulate the ischemia/reperfusion process in vivo and in vitro, respectively, and the relative expression and regulatory effect of miR-144-3p were determined. The target of miR-144-3p was also verified by a luciferase reporter assay. We found that miR-144-3p was significantly downregulated in mouse myocardium subjected to I/R and cardiomyocytes subjected to H/R. Upregulation of miR-144-3p significantly attenuated MIRI in vivo and in vitro. A Ca²⁺-activated chloride channel-TMEM16A (ANO1)-was identified as a target gene of miR-144-3p through bioinformatic analysis. The interaction between miR-144-3p and the 3'-untranslated region of ANO1 was confirmed with dual-luciferase reporter assay, RNA immunoprecipitation assay, real-time quantitative polymerase chain reaction, and western blot analysis. Moreover, by targeting ANO1, miR-144-3p inhibited the activation of NLRP3 inflammasome inflammatory signals in myocardial cells. Collectively, the present study provides a novel insight into the role of miR-144-3p in the inhibition of MIRI, suggesting that the miR-144-3p/ANO1 axis may be a putative therapeutic target in myocardial ischemia.

Long Non-Coding RNA SOX2 Overlapping Transcript Aggravates H9c2 Cell Injury via the miR-215-5p/ZEB2 Axis and Promotes Ischemic Heart Failure in a Rat Model

Heart failure is a common cardiovascular disease, which has been regarded as one of the highest health care costs with high morbidity and mortality in the western countries. Long noncoding RNAs have been widely reported to regulate the initiation or progression of cardiovascular diseases. However, the specific role of SOX2 overlapping transcript (SOX2-OT) in ischemic heart failure remains uncharacterized. The present study aimed to explore the function and mechanism of SOX2-OT in ischemic heart failure. The starBase website was used to predict potential miRNAs or target mRNAs. Western blot assay was implemented to test collagen protein levels. Functional assays were conducted to evaluate the effects of SOX2-OT on H9c2 cell viability and apoptosis. RNA pull down and luciferase reporter assays were used to confirm the combination between miR-215-5p and SOX2-OT. We found out that SOX2-OT level was increased by oxygen glucose deprivation/reoxygenation treatment in H9c2 cells. Silencing of SOX2-OT ameliorated cell injury by promoting cell viability, inhibiting cell apoptosis and reducing productions of collagens. Mechanistically, miR-215-5p was confirmed to bind with SOX2-OT after prediction and screening. In addition, we discovered that miR-215-5p negatively regulated zinc finger E-box binding homeobox 2 (ZEB2) protein level by directly binding with ZEB2 3' untranslated region. Finally, we verified that SOX2-OT aggravated cell injury by targeting ZEB2 in H9c2 cells. In conclusion, SOX2-OT aggravated heart failure in vivo and promoted H9c2 cell injury via the miR-215-5p/ZEB2 axis in vitro, implying a novel insight into heart failure treatment.