LncRNA MALAT1 prevents the protective effects of miR-125b-5p against acute myocardial infarction through positive regulation of NLRC5

Ferroptosis contributing to cardiomyocyte injury induced by silica nanoparticles via miR-125b-2-3p/HO-1 signaling

BACKGROUND

Amorphous silica nanoparticles (SiNPs) have been gradually proven to threaten cardiac health, but pathogenesis has not been fully elucidated. Ferroptosis is a newly defined form of programmed cell death that is implicated in myocardial diseases. Nevertheless, its role in the adverse cardiac effects of SiNPs has not been described.

RESULTS

We first reported the induction of cardiomyocyte ferroptosis by SiNPs in both in vivo and in vitro. The sub-chronic exposure to SiNPs through intratracheal instillation aroused myocardial injury, characterized by significant inflammatory infiltration and collagen hyperplasia, accompanied by elevated CK-MB and cTnT activities in serum. Meanwhile, the activation of myocardial ferroptosis by SiNPs was certified by the extensive iron overload, declined FTH1 and FTL, and lipid peroxidation. The correlation analysis among detected indexes hinted ferroptosis was responsible for the SiNPs-aroused myocardial injury. Further, in vitro tests, SiNPs triggered iron overload and lipid peroxidation in cardiomyocytes. Concomitantly, altered expressions of TfR, DMT1, FTH1, and FTL indicated dysregulated iron metabolism of cardiomyocytes upon SiNP stimuli. Also, shrinking mitochondria with ridge fracture and ruptured outer membrane were noticed. To note, the ferroptosis inhibitor Ferrostatin-1 could effectively alleviate SiNPs-induced iron overload, lipid peroxidation, and myocardial cytotoxicity. More importantly, the mechanistic investigations revealed miR-125b-2-3p-targeted HO-1 as a key player in the induction of ferroptosis by SiNPs, probably through regulating the intracellular iron metabolism to mediate iron overload and ensuing lipid peroxidation.

CONCLUSIONS

Our findings firstly underscored the fact that ferroptosis mediated by miR-125b-2-3p/HO-1 signaling was a contributor to SiNPs-induced myocardial injury, which could be of importance to elucidate the toxicity and provide new insights into the future safety applications of SiNPs-related nano products.

lncRNA DLX6-AS1 Promotes Myocardial Ischemia-Reperfusion Injury through Mediating the miR-204-5p/FBXW7 Axis

Myocardial ischemia-reperfusion (IR) injury is the restoration of blood flow post ischemia, which threatens the human life. Long noncoding RNA distal-less homeobox 6 antisense 1 (DLX6-AS1) has been found to take part in the IR-induced cerebral injury. Here, we determined the functional role of DLX6-AS1 in IR-induced myocardial injury. We ligated the left anterior descending coronary artery of rats to induce IR injury. IR injury rats exhibited severe tissue damage and increase of infraction size. The levels of lactate dehydrogenase (LDH), creatine kinase (CK), proinflammatory factors including MCP-1, IL-6, and IL-1β, and cell apoptosis were also enhanced in IR rats, indicating that IR induced significant myocardial injury in rats. DLX6-AS1 expression was elevated in the myocardial tissues of IR injury rats, while DLX6-AS1 deficiency alleviated IR-induced myocardial injury in rats by reducing inflammatory response and cell apoptosis. Moreover, rat embryonic cardiomyocyte cell line H9c2 was subjected to hypoxia reoxygenation (HR). DLX6-AS1 was upregulated in the HR-treated H9c2 cells, and DLX6-AS1 enhanced the expression of F-box and WD40 repeat domain-containing 7 (FBXW7) by sponging miR-204-5p. Inhibition of DLX6-AS1 inhibited inflammatory response and cell apoptosis in H9c2 cells via miR-204-5p/FBXW7 axis. In conclusion, this work demonstrates that DLX6-AS1 accelerates myocardial IR injury through regulating miR-204-5p/FBXW7 axis. Thus, this work provides a novel ceRNA DLX6-AS1/miR-204-5p/FBXW7 axis in myocardial IR injury, and DLX6-AS1 may be a potential target for the treatment of myocardial IR injury.

ANRIL overexpression globally induces expression and alternative splicing of genes involved in inflammation in HUVECs

Long non‑coding (lnc)RNAs serve important cellular functions and certain lncRNAs have roles in different mechanisms of gene regulation. lncRNA‑antisense non‑coding RNA in the INK4 locus (ANRIL) affects cell inflammation; however, the potential genes underlying the inflammatory response regulated by ANRIL remain unclear. In the present study, the potential function of ANRIL in regulating gene expression and alternative splicing was assessed. ANRIL‑regulated human umbilical vein endothelial cell (HUVEC) transcriptome was obtained using high‑throughput RNA sequencing (RNA‑seq) to evaluate the potential role of ANRIL. Following plasmid transfection, gene expression profile and alternative splicing pattern of HUVECs overexpressing ANRIL were analyzed using RNA‑seq. ANRIL overexpression affected the transcription levels of genes associated with the inflammatory response, NF‑κB signaling pathway, type I interferon‑mediated signal transduction pathway and innate immune response. ANRIL regulated the alternative splicing of hundreds of genes with functions such as gene expression, translation, DNA repair, RNA processing and participation in the NF‑κB signaling pathway. Many of these genes serve a key role in the inflammatory response. ANRIL‑regulated inflammatory response may be achieved by regulating alternate splicing and transcription. The present study broadened the understanding of ANRIL‑mediated gene regulation mechanisms and clarified the role of ANRIL in mediating inflammatory response mechanisms.

LncRNA FGD5-AS1 reduces cardiomyocyte apoptosis and inflammation by modulating Akt and miR-223-3p expression

OBJECTIVES

Long non-coding RNAs (lncRNAs) are known to be involved in heart development and function. In this study, we aimed to explore the effect of the lncRNA FGD5 antisense RNA 1 (FGD5-AS1) on acute myocardial infarction (AMI) by targeting miR-223-3p.

METHODS

An AMI model was established both in vivo and in vitro. The levels of FGD5-AS1, miR-223-3p and inflammatory factors were detected by real-time quantitative reverse transcription PCR. Cardiomyocyte apoptosis was assessed using TdT-mediated dUTP nick-end labeling assay. The protein levels of cleaved caspase-3, Bcl-2 and Bax were examined using Western blot. Cardiac function was evaluated using hemodynamic analysis and hematoxylin-eosin and Masson's trichrome staining. In addition, an underlying competitive endogenous RNA mechanism was revealed by bioinformatics analysis, dual-luciferase reporter assay and rescue experiments.

RESULTS

We found decreased expression of FGD5-AS1 in AMI. Furthermore, FGD5-AS1 expression significantly decreased the infarct size, improved cardiac performance and attenuated cardiac fibrosis by reducing myocardial apoptosis and inflammation. miR-223-3p was a direct target of FGD5-AS1. Moreover, miRNA-223-3p directly downregulated the expression of phosphorylated Akt in primary neonatal rat cardiomyocytes. Further experiments demonstrated that FGD5-AS1 modulated Akt activity to reduce myocardial injury through miR-223-3p.

CONCLUSION

The FGD5-AS1/miR-223-3p/Akt pathway is involved in AMI, suggesting that FGD5-AS1 may act as a potential biomarker and therapeutic target for AMI.

MALAT1 regulates hypertrophy of cardiomyocytes by modulating the miR-181a/HMGB2 pathway

Noncoding RNAs are important for the regulation of cardiac hypertrophy. The function of MALAT1 (a long noncoding mRNA), miR-181a, and HMGB2, their contribution to cardiac hypertrophy, and the regulatory relationship between them during this process remain unknown. In the present study, we treated primary cardiomyocytes with angiotensin II (Ang II) to mimic cardiac hypertrophy. MALAT1 expression was significantly downregulated in Ang II-treated cardiomyocytes compared with control cardiomyocytes. Ang II-induced cardiac hypertrophy was suppressed by overexpression of MALAT1 and promoted by genetic knockdown of MALAT1. A dual-luciferase reporter assay demonstrated that MALAT1 acted as a sponge for miR-181a and inhibited its expression during cardiac hypertrophy. Cardiac hypertrophy was suppressed by overexpression of an miR-181a inhibitor and enhanced by overexpression of an miR-181a mimic. HMGB2 was downregulated during cardiac hypertrophy and was identified as a target of miR-181a by bioinformatics analysis and a dual-luciferase reporter assay. miR-181a overexpression decreased the mRNA and protein levels of HMGB2. Rescue experiments indicated that MALAT1 overexpression reversed the effect of miR-181a on HMGB2 expression. In summary, the results of the present study show that MALAT1 acts as a sponge for miR-181a and thereby regulates expression of HMGB2 and development of cardiac hypertrophy. The novel MALAT1/miR-181a/HMGB2 axis might play a crucial role in cardiac hypertrophy and serve as a new therapeutic target.

LncRNA HOTTIP Knockdown Attenuates Acute Myocardial Infarction via Regulating miR-92a-2/c-Met Axis

Increasing investigations have focused on long non-coding RNAs (lncRNAs) in various human diseases, including acute myocardial infarction (AMI). Although lncRNA HOTTIP has been identified to play an important role in coronary artery diseases, its role and specific mechanism in AMI remain unclear. To investigate the potential role of HOTTIP in MI, HOTTIP expression in hypoxia-treated cardiomyocytes and myocardial tissues of MI mice was evaluated. The potential targets of HOTTIP and miR-92a-2 were predicted using Starbase and Targetscan. To further determine the cardio-protective effects of HOTTIP in vivo, si-HOTTIP and miR-92a-2 mimics were individually or co-injected into mice through intramyocardial injection. Moreover, their roles were further confirmed in rescue experiments. HOTTIP was significantly upregulated in ischemic myocardium of MI mice and hypoxia-induced cardiomyocytes. Moreover, HOTTIP knockdown markedly promoted cardiomyocyte growth and inhibited cardiomyocyte apoptosis in vitro. Luciferase reporter assay showed that HOTTIP could directly sponge miR-92a-2 to negatively regulate miR-92a-2 expression. In addition, c-Met was identified as a direct target of miR-92a-2, and their correlation was confirmed by luciferase reporter assay. MiR-92a-2 overexpression significantly enhanced the protective effect of HOTTIP knockdown against AMI through partially inhibiting c-Met expression. Our results demonstrated that HOTTIP downregulation attenuated AMI progression via the targeting miR-92a-2/c-Met axis and suggested that HOTTIP might be a potential therapeutic target for AMI.

LncRNA Neat1/miR-298-5p/Srpk1 Contributes to Sevoflurane-Induced Neurotoxicity

Sevoflurane is a widely used volatile anesthetic, that can cause long-term neurotoxicity and learning and memory impairment. Long non-coding RNAs (lncRNAs) have been demonstrated to function as key mediators in neurotoxicity. This study aimed to investigate the effects of lncRNA Neat1 on sevoflurane-induced neurotoxicity. The expression of Neat1, miR-298-5p, and Srpk1 was measured by RT-qPCR. Cell viability, cell apoptosis, inflammation markers, and reactive oxygen species (ROS) generation were examined by CCK-8, TUNEL, ELISA, and the ROS kit. The interaction between miR-298-5p and Neat1 or Srpk1 was confirmed by luciferase reporter assay. In our study, it was found that sevoflurane aggravated neurotoxicity through inhibiting cell viability and enhancing cell apoptosis, neuroinflammation, and ROS generation. Neat1 was up-regulated in sevoflurane-treated HT22 cells, and Neat1 knockdown improved sevoflurane-mediated neurotoxicity. Through the exploration of the ceRNA mechanism, we found that Neat1 bound with miR-298-5p, and Srpk1 was a direct target gene of miR-298-5p. Finally, rescue assays proved that up-regulation of Srpk1 reversed the effects of Neat1 knockdown on neurotoxicity. In conclusion, our study revealed that lncRNA Neat1 facilitated sevoflurane-stimulated neurotoxicity by sponging miR-298-5p to up-regulate Srpk1. These findings might provide novel insights into the treatment of sevoflurane-induced neurotoxicity.

MSCs-Derived Extracellular Vesicles Carrying miR-212-5p Alleviate Myocardial Infarction-Induced Cardiac Fibrosis via NLRC5/VEGF/TGF-β1/SMAD Axis

The purpose of the present study was to define the role of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) in the progression of myocardial infarction (MI)-induced cardiac fibrosis. An in vitro cell model of hypoxia-induced cardiac fibrosis was constructed in cardiac fibroblasts (CFs). miR-212-5p was poorly expressed in clinical pathological samples and animal models of cardiac fibrosis caused by MI, while miR-212-5p expression was enriched in EVs released from MSCs. EVs from MSCs were isolated, evaluated, and co-cultured with CFs. Dual-luciferase reporter gene assay revealed that miR-212-5p negatively targeted NLRC5 progression of cardiac fibrosis. Following loss- and gain-function assay, EVs expressing miR-212-5p protected against cardiac fibrosis evidenced by reduced levels of α-SMA, Collagen I, TGF-β1, and IL-1β. In vivo experiments further confirmed the above research results. Collectively, EVs from MSCs expressing miR-212-5p may attenuate MI by suppressing the NLRC5/VEGF/TGF-β1/SMAD axis.

The Regulatory NOD-Like Receptor NLRC5 Promotes Ganglion Cell Death in Ischemic Retinopathy by Inducing Microglial Pyroptosis

Retinal ischemia is a common pathological event that can result in retinal ganglion cell (RGC) death and irreversible vision loss. The pathogenic mechanisms linking retinal ischemia to RGC loss and visual deficits are uncertain, which has greatly hampered the development of effective treatments. It is increasingly recognized that pyroptosis of microglia contributes to the indirect inflammatory death of RGCs. In this study, we report a regulatory NOD-like receptor, NOD-, LRR- and CARD-containing 5 (NLRC5), as a key regulator on microglial pyroptosis and the retinal ischemia process. Through an in-depth analysis of our recently published transcriptome data, we found that NLRC5 was significantly up-regulated in retina during ischemia–reperfusion injury, which were further confirmed by subsequent detection of mRNA and protein level. We further found that NLRC5 was upregulated in retinal microglia during ischemia, while NLRC5 knockdown significantly ameliorated retinal ischemic damage and RGC death. Mechanistically, we revealed that knockdown of NLRC5 markedly suppressed gasdermin D (GSDMD) cleavage and activation of interleukin-1β (IL-1β) and caspase-3, indicating that NLRC5 promotes both microglial pyroptosis and apoptosis. Notably, we found that NLRC5 directly bound to NLRP3 and NLRC4 in inflammasomes to cooperatively drive microglial pyroptosis and apoptosis mediating retinal ischemic damage. Overall, these findings reveal a previously unidentified key contribution of NLRC5 signaling to microglial pyroptosis under ischemia or hypoxia conditions. This NLRC5-dependent pathway may be a novel therapeutic target for treatment of ischemic retinopathy.

Role of N6-Methyladenosine RNA Modification in Cardiovascular Disease

Despite treatments being improved and many risk factors being identified, cardiovascular disease (CVD) is still a leading cause of mortality and disability worldwide. N⁶-methyladenosine (m⁶A) is the most common, abundant, and conserved internal modification in RNAs and plays an important role in the development of CVD. Many studies have shown that aabnormal m⁶A modifications of coding RNAs are involved in the development of CVD. In addition, non-coding RNAs (ncRNAs) exert post-transcriptional regulation in many diseases including CVD. Although ncRNAs have also been found to be modified by m⁶A, the studies on m⁶A modifications of ncRNAs in CVD are currently lacking. In this review, we summarized the recent progress in understanding m⁶A modifications in the context of coding RNAs and ncRNAs, as well as their regulatory roles in CVD.

Long non-coding RNA MALAT1 and its target microRNA-125b associate with disease risk, severity, and major adverse cardiovascular event of coronary heart disease

Background

This study aimed to explore the correlation of long non‐coding RNA metastasis‐associated lung adenocarcinoma transcript 1 (lncRNA MALAT1) with microRNA (miR)‐125b and further investigated their associations with disease risk, severity, and prognosis of coronary heart disease (CHD).

Methods

Totally, 230 patients who underwent diagnostic coronary angiography were recruited; meanwhile, 140 of them were diagnosed as CHD and the remaining 90 non‐CHD patients served as controls. Plasma sample was collected from each participant for lncRNA MALAT1 and miR‐125b mRNA expression detection by reverse transcription‐quantitative polymerase chain reaction. The extent of coronary stenosis was evaluated by the Gensini score, and major adverse cardiovascular event (MACE) occurrence during the follow‐up was documented in CHD patients.

Results

Long non‐coding RNA metastasis‐associated lung adenocarcinoma transcript 1 relative expression was increased, but miR‐125b relative expression was decreased in CHD patients compared with controls. ROC curve exhibited that lncRNA MALAT1 and miR‐125b were of good value in differentiating CHD patients from controls, and further logistic regression analysis verified their independent correlation with CHD risk. Furthermore, lncRNA MALAT1 presented a closely negative correlation with miR‐125b in CHD patients, while it presented a weakly negative association with miR‐125b in controls. In CHD patients, lncRNA MALAT1 was positively correlated with Gensini score, total cholesterol, low‐density lipoprotein cholesterol, C‐reactive protein, tumor necrosis factor α, interleukin (IL)‐1β, IL‐6, IL‐17, and accumulating MACE occurrence; reversely, miR‐125b presented a opposite trend.

Conclusion

Long non‐coding RNA metastasis‐associated lung adenocarcinoma transcript 1 might be associated with increased CHD risk, severity, and accumulating MACE incidence via negative interaction with miR‐125b, suggesting their possible clinical application as biomarkers in the CHD screening and surveillance.

Long Noncoding RNA/Circular RNA-miRNA-mRNA Axes in Ischemia-Reperfusion Injury

Ischemia-reperfusion injury (IRI) elicits tissue injury involved in a wide range of pathologies. Multiple studies have demonstrated that noncoding RNAs (ncRNAs), including long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs), participate in the pathological development of IRI, and they may act as biomarkers, therapeutic targets, or prognostic indicators. Nonetheless, the specific molecular mechanisms of ncRNAs in IRI have not been completely elucidated. Regulatory networks among lncRNAs/circRNAs, miRNAs, and mRNAs have been the focus of attention in recent years. Studies on the underlying molecular mechanisms have contributed to the discovery of therapeutic targets or strategies in IRI. In this review, we comprehensively summarize the current research on the lncRNA/circRNA-miRNA-mRNA axes and highlight the important role of these axes in IRI.

Long Non-Coding RNA SLC25A21-AS1 Promotes Multidrug Resistance in Nasopharyngeal Carcinoma by Regulating miR-324-3p/IL-6 Axis

Background

Nasopharyngeal carcinoma (NPC), one of the most common types of head and neck tumor, occurred in the epithelial lining of the nasopharynx and is mainly prevalent in Southeast Asia and Southern China. However, the molecular mechanisms of NPC multidrug resistance still remained largely unclear.

Methods

The qRT-PCR assay was performed to examine SLC25A21-AS1, miR-324-3p and IL-6 expression in NPC tissues and cell. The CCK8 assay and colony formation assay were used to detect cell growth. In addition, CCK8 assay was performed to detect IC₅₀ values of different drugs in NPC cell.

Results

In this study, we found that SLC25A21-AS1 expression was increased in NPC tissues and cell line, and knockdown of SLC25A21-AS1 inhibited cell growth and MDR in NPC cell. Moreover, SLC25A21-AS1 acted as a ceRNA for miR-324-3p and facilitates NPC cell growth and MDR by regulating the miR-324-3p/IL-6 axis.

Conclusion

Our findings demonstrated the role of SLC25A21-AS1/miR-324-3p/IL-6 axis in cell growth and MDR in NPC, which might be a potential prognostic and diagnostic marker in NPC patients and provide new insight into the molecular mechanism of MDR in NPC chemotherapy.