Inhibition of the long non-coding RNA NEAT1 protects cardiomyocytes from hypoxia in vitro via decreased pri-miRNA processing

The roles of long noncoding RNA NEAT1 in cardiovascular diseases

The morbidity of cardiovascular diseases (CVDs) gradually increases worldwide. Long noncoding RNAs (lncRNAs) are a large class of non-(protein)-coding RNAs with lengths beyond 200 nucleotides. Increasing evidence suggests that lncRNA NEAT1 plays important roles in the pathogenesis of CVDs, such as myocardial infarction, heart failure, myocardial ischemia-reperfusion (I/R) injury, atherosclerosis, hypertension, cardiomyopathy, and others. We summarized the current studies of NEAT1 in CVDs, which shed light on the understanding of the molecular mechanisms of CVDs and understanding the therapeutic potential of NEAT1.

NEAT1 in inflammatory infectious diseases: An integrated perspective on molecular modulation

The long non-coding RNA (lncRNA), NEAT1, has emerged as a central figure in the intricate network of molecular regulators in inflammatory infectious diseases (IIDs). The review initiates a comprehensive exploration of NEAT1's multifaceted roles and molecular interactions in the context of these complex diseases. The study begins by acknowledging the global health burden of IIDs, underscoring the urgency for innovative insights into their pathogenesis and therapeutic avenues. NEAT1 is introduced as a pivotal lncRNA with growing relevance in immune responses and inflammatory processes. The core of this review unravels the NEAT1 landscape, elucidating its involvement in the modulation of immune signalling pathways, regulation of inflammatory cytokines, and interactions with various immune cells during infection. It explores NEAT1's role in orchestrating immune responses and balancing host defence mechanisms with the risk of immunopathology. Furthermore, the review underscores the clinical significance of NEAT1 in infectious diseases, discussing its associations with disease severity, prognosis, and potential as a diagnostic and therapeutic target. It provides insights into ongoing research endeavours aimed at harnessing NEAT1 for innovative disease management strategies, including developing RNA-based therapeutics. Concluding on a forward-looking note, the review highlights the broader implications of NEAT1 in the context of emerging infectious diseases and the possibility for precision medicine approaches that leverage NEAT1's regulatory capacities. In summary, this review illuminates the pivotal role of NEAT1 in IIDs by navigating its complex landscape, offering profound insights into its implications for disease pathogenesis and the development of targeted therapies.

Chlorogenic acid protects against myocardial ischemia-reperfusion injury in mice by inhibiting Lnc Neat1/NLRP3 inflammasome-mediated pyroptosis

Increasing evidences demonstrate that chlorogenic acid (CGA), a polyphenol with multiple effects such as anti-inflammatory and anti-oxidation, protects against myocardial ischemia-reperfusion injury (MIRI) in vitro and in vivo. But its detailed cardiac protection mechanism is still unclear. The MIRI mice model was established by ligating the left anterior descending branch (LAD) of the left coronary artery in C57BL/6 mice. Sixty C57BL/6 mice were randomly divided into four groups. CGA group and CGA + I/R group (each group n = 15) were gavaged with 30 mg/kg/day CGA for 4 weeks. Sham group and I/R group mice (each group n = 15) were administered equal volumes of saline. In vitro MIRI model was constructed by hypoxia and reoxygenation of HL-1 cardiomyocytes. The results showed that CGA pretreatment reduced myocardial infarction size and cTnT contents in serum, simultaneously reduced the levels of Lnc Neat1 expression and attenuated NLRP3 inflammasome-mediated pyroptosis in myocardial tissue. Consistent with in vivo results, the pretreatment of 0.2 μM and 2 μM CGA for 12 h in HL-1 cardiomyocytes depressed hypoxia/reoxygenation-induced Lnc Neat1 expression, NLRP3 inflammasome activation and pyroptosis. Lnc Neat1 shRNA transfection mediated by lentivirus in HL-1 cardiomyocytes significantly reduced activation of NLRP3 inflammasome and pyroptosis. Our findings suggest that CGA protects against MIRI by depressing Lnc Neat1 expression and NLRP3 inflammasome-mediated pyrotosis. Inhibiting the levels of Lnc Neat1 expression may be a therapeutic strategy for MIRI.

Extracellular lncRNAs secreted and absorbed by cardiomyocytes

Exosomes are membrane-surrounded extracellular vesicles released by almost all cell types, which mediate intercellular communications by delivering bioactive molecules from secretory cells to recipient cells. Long noncoding RNAs (lncRNAs) are a large class of non-(protein)-coding RNAs with lengths exceeding 200 nucleotides that are very active in the development of cardiovascular diseases (CVDs). Increasing evidence suggests that exosomal lncRNAs also play important roles in the progress of CVDs. We focus on the current available studies regarding these extracellular lncRNAs secreted and absorbed by cardiomyocytes and their functional roles in CVDs, hopefully providing a basis for deeper understanding of the pathological mechanisms of CVDs and their potential for clinical diagnosis and therapy.

Spatiotemporal Expression and Functional Analysis of miRNA-22 in the Developing Secondary Palate

OBJECTIVE

Normal development of the embryonic orofacial region requires precise spatiotemporal coordination between numerous genes. MicroRNAs represent small, single-stranded, non-coding molecules that regulate gene expression. This study examines the role of microRNA-22 (miR-22) in murine orofacial ontogeny.

METHODS

Spatiotemporal and differential expression of miR-22 (mmu-miR-22-3p) within the developing secondary palate was determined by in situ hybridization and quantitative real-time PCR, respectively. Bioinformatic approaches were used to predict potential mRNA targets of miR-22 and analyze their association with cellular functions indispensable for normal orofacial ontogeny. An in vitro palate organ culture system was used to assess the role of miR-22 in secondary palate development.

RESULTS

There was a progressive increase in miR-22 expression from GD12.5 to GD14.5 in palatal processes. On GD12.5 and GD13.5, miR-22 was expressed in the future oral, nasal, and medial edge epithelia. On GD14.5, miR-22 expression was observed in the residual midline epithelial seam (MES), the nasal epithelium and the mesenchyme, but not in the oral epithelium. Inhibition of miR-22 activity in palate organ cultures resulted in failure of MES removal. Bioinformatic analyses revealed potential mRNA targets of miR-22 that may play significant roles in regulating apoptosis, migration, and/or convergence/extrusion, developmental processes that modulate MES removal during palatogenesis.

CONCLUSIONS

Results from the current study suggest a key role for miR-22 in the removal of the MES during palatogenesis and that miR-22 may represent a potential contributor to the etiology of cleft palate.

LncRNA nuclear-enriched abundant transcript 1 aggravates cerebral ischemia/reperfusion injury through activating early growth response-1/RNA binding motif protein 25 axis

Ischemic stroke is a major global health issue. Ischemia and subsequent reperfusion results in stroke-related brain injury. Previous studies have demonstrated that nuclear-enriched abundant transcript 1 (NEATa and early growth response 1 (EGR1) are involved in ischemia reperfusion (IR) injury). In this study, we aimed to explore the roles of NEAT1/EGR1 axis as well as its downstream effector RNA binding motif protein 25 (RBM25) in cerebral IR injury. Oxygen-glucose deprivation/reperfusion (OGD/R) and middle cerebral artery occlusion (MCAO) were used to establish in vitro and in vivo models of cerebral IR injury, respectively. According to our data, NEAT1, EGR1, and RBM25 levels were elevated in OGD/R-exposed SK-N-SH and SH-SY5Y cells and cerebral cortex of MCAO mice. NEAT1, EGR1, or RBM25 knockdown effectively reduced infarct volumes and apoptosis, and improved neurological function. Mechanistically, NEAT1 directly interacted with EGR1, which restrained WW domain containing E3 ubiquitin protein ligase 1 (WWP1)-mediated ubiquitination of EGR1 and subsequently caused EGR1 accumulation. EGR1 bound to RBM25 promoter and transcriptionally activated RBM25. Rescue experiments indicated that RBM25 overexpression abolished the therapeutic effects of NEAT1 knockdown. In conclusion, this work identified a novel NEAT1/EGR1/RBM25 axis in potentiating brain injury after IR insults, suggesting a potential therapeutic target for ischemic stroke.

Application of Induced Pluripotent Stem Cell-Derived Models for Investigating microRNA Regulation in Developmental Processes

Advances in induced pluripotent stem cell (iPSC) techniques have opened up new perspectives in research on developmental biology. Compared with other sources of human cellular models, iPSCs present a great advantage in hosting the unique genotype background of donors without ethical concerns. A wide spectrum of cellular and organoid models can be generated from iPSCs under appropriate in vitro conditions. The pluripotency of iPSCs is orchestrated by external signalling and regulated at the epigenetic, transcriptional and posttranscriptional levels. Recent decades have witnessed the progress of studying tissue-specific expressions and functions of microRNAs (miRNAs) using iPSC-derived models. MiRNAs are a class of short non-coding RNAs with regulatory functions in various biological processes during development, including cell migration, proliferation and apoptosis. MiRNAs are key modulators of gene expression and promising candidates for biomarker in development; hence, research on the regulation of human development by miRNAs is expanding. In this review, we summarize the current progress in the application of iPSC-derived models to studies of the regulatory roles of miRNAs in developmental processes.

An update on the functional roles of long non‑coding RNAs in ischemic injury (Review)

Ischemic injuries result from ischemia and hypoxia in cells. Tissues and organs receive an insufficient supply of nutrients and accumulate metabolic waste, which leads to the development of inflammation, fibrosis and a series of other issues. Ischemic injuries in the brain, heart, kidneys, lungs and other organs can cause severe adverse effects. Acute renal ischemia induces acute renal failure, heart ischemia induces myocardial infarction and cerebral ischemia induces cerebrovascular accidents, leading to loss of movement, consciousness and possibly, life-threatening disabilities. Existing evidence suggests that long non-coding RNAs (lncRNAs) are regulatory sequences involved in transcription, post-transcription, epigenetic regulation and multiple physiological processes. lncRNAs have been shown to be differentially expressed following ischemic injury, with the severity of the ischemic injury being affected by the upregulation or downregulation of certain types of lncRNA. The present review article provides an extensive summary of the functional roles of lncRNAs in ischemic injury, with a focus on the brain, heart, kidneys and lungs. The present review mainly summarizes the functional roles of lncRNA MALAT1, lncRNA MEG3, lncRNA H19, lncRNA TUG1, lncRNA NEAT1, lncRNA AK139328 and lncRNA CAREL, among which lncRNA MALAT1, in particular, plays a crucial role in ischemic injury and is currently a hot research topic.

LINC00488 Induces Tumorigenicity in Retinoblastoma by Regulating microRNA-30a-5p/EPHB2 Axis

OBJECTIVE

LINC00488 confers oncogenic activity in the progression of some tumors. Hence, the target of the study was about to specify LINC00488-mediated network in retinoblastoma (RB).

METHODS

LINC00488 expression was tested in RB clinical tissues. siRNA targeting LINC00488 or miR-30a-5p mimic was introduced into RB cell line (Y79) to observe cellular biological functions. The relationship between LINC00488, miR-30a-5p and EPHB2 was verified. Afterward, the role of miR-30a-5p involved in RB through targeted regulation of EPHB2 was probed in vitro and in vivo.

RESULTS

LINC00488 was induced in RB tissue and cells. LINC00488 knockdown or miR-30a-5p upregulation depressed the malignant activities of Y79 cells. LINC00488 could sponge miR-30a-5p that targeted EPHB2. EPHB2, and EPHB2 overexpression counteracted miR-30a-5p restoration-induced inhibition of Y79 cell development in vitro and in vivo.

CONCLUSION

LINC00488 induces tumorigenicity in RB by binding to miR-30a-5p to target EPHB2, which may offer a new clue of RB treatment from an lncRNA-miRNA-mRNA network.

HIF-1α-regulated lncRNA-TUG1 promotes mitochondrial dysfunction and pyroptosis by directly binding to FUS in myocardial infarction

Myocardial infarction (MI) is a fatal heart disease that affects millions of lives worldwide each year. This study investigated the roles of HIF-1α/lncRNA-TUG1 in mitochondrial dysfunction and pyroptosis in MI. CCK-8, DHE, lactate dehydrogenase (LDH) assays, and JC-1 staining were performed to measure proliferation, reactive oxygen species (ROS), LDH leakage, and mitochondrial damage in hypoxia/reoxygenation (H/R)-treated cardiomyocytes. Enzyme-linked immunoassay (ELISA) and flow cytometry were used to detect LDH, creatine kinase (CK), and its isoenzyme (CK-MB) levels and caspase-1 activity. Chromatin immunoprecipitation (ChIP), luciferase assay, and RNA-immunoprecipitation (RIP) were used to assess the interaction between HIF-1α, TUG1, and FUS. Quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting, and immunohistochemistry were used to measure HIF-1α, TUG1 and pyroptosis-related molecules. Hematoxylin and eosin (HE), 2,3,5-triphenyltetrazolium chloride (TTC), and terminal deoxynucleotidyl transferase dUTP risk end labelling (TUNEL) staining were employed to examine the morphology, infarction area, and myocardial injury in the MI mouse model. Mitochondrial dysfunction and pyroptosis were induced in H/R-treated cardiomyocytes, accompanied by an increase in the expression of HIF-α and TUG1. HIF-1α promoted TUG1 expression by directly binding to the TUG1 promoter. TUG1 silencing inhibited H/R-induced ROS production, mitochondrial injury and the expression of the pyroptosis-related proteins NLRP3, caspase-1 and GSDMD. Additionally, H/R elevated FUS levels in cardiomyocytes, which were directly inhibited by TUG1 silencing. Fused in sarcoma (FUS) overexpression reversed the effect of TUG1 silencing on mitochondrial damage and caspase-1 activation. However, the ROS inhibitor N-acetylcysteine (NAC) promoted the protective effect of TUG1 knockdown on H/R-induced cardiomyocyte damage. The in vivo MI model showed increased infarction, myocardial injury, ROS levels and pyroptosis, which were inhibited by TUG1 silencing. HIF-1α targeting upregulated TUG1 promotes mitochondrial damage and cardiomyocyte pyroptosis by combining with FUS, thereby promoting the occurrence of MI. HIF-1α/TUG1/FUS may serve as a potential treatment target for MI.

Direct coculture of human pluripotent stem cell-derived cardiac progenitor cells with epicardial cells induces cardiomyocyte proliferation and reduces sarcomere organization

Epicardial cells (EpiCs) are necessary for myocardium formation, yet little is known about crosstalk between EpiCs and cardiomyocytes (CMs) during development and the potential impact of EpiCs on CM maturation. To investigate the effects of EpiCs on CM commitment and maturation, we differentiated human pluripotent stem cells (hPSCs) to cardiac progenitor cells (CPCs) and EpiCs, and cocultured EpiCs and CPCs for two weeks. When EpiCs were allowed to form epicardial-derived cells, we observed increased expression of cTnI in developing CMs. In the presence of the TGFβ inhibitor A83-01, EpiCs remained in the epicardial state and induced CM proliferation, increased MLC2v expression, and led to less organized sarcomeres. These effects were not observed if CPCs were treated with EpiC-conditioned medium or if CPCs were indirectly cocultured with EpiCs. Finally, single cell RNA sequencing identified that EpiC-CPC coculture had bi-directional effects on transcriptional programs in EpiCs and CMs, and biased EpiC lineages from a SFRP2-enriched population to a DLK1- or C3-enriched population. This work suggests important crosstalk between EpiCs and CMs during differentiation which can be used to influence cell fate and improve the ability to generate cardiac cells and tissues for in vitro models and development of cardiac cellular therapies.

Long non-coding RNA Neat1 and paraspeckle components are translational regulators in hypoxia

Internal ribosome entry sites (IRESs) drive translation initiation during stress. In response to hypoxia, (lymph)angiogenic factors responsible for tissue revascularization in ischemic diseases are induced by the IRES-dependent mechanism. Here, we searched for IRES trans-acting factors (ITAFs) active in early hypoxia in mouse cardiomyocytes. Using knock-down and proteomics approaches, we show a link between a stressed-induced nuclear body, the paraspeckle, and IRES-dependent translation. Furthermore, smiFISH experiments demonstrate the recruitment of IRES-containing mRNA into paraspeckle during hypoxia. Our data reveal that the long non-coding RNA Neat1, an essential paraspeckle component, is a key translational regulator, active on IRESs of (lymph)angiogenic and cardioprotective factor mRNAs. In addition, paraspeckle proteins p54^nrb and PSPC1 as well as nucleolin and RPS2, two p54^nrb-interacting proteins identified by mass spectrometry, are ITAFs for IRES subgroups. Paraspeckle thus appears as a platform to recruit IRES-containing mRNAs and possibly host IRESome assembly. Polysome PCR array shows that Neat1 isoforms regulate IRES-dependent translation and, more widely, translation of mRNAs involved in stress response.

Krüppel-like factor 15 reduces ischemia-induced apoptosis involving regulation of p38/MAPK signaling

Background Cardiomyocyte apoptosis is a characteristic of a variety of cardiac diseases including myocardial infarction (MI). Krüppel-like factor 15 (KLF15) is a transcription factor of Krüppel family that plays an important part in cardiovascular diseases. However, the function and the underlying mechanism of KLF15 in MI remain unknown. Methods and Results The expression of KLF15 was downregulated both in ischemic myocardium of MI mice model and hypoxia-treated neonatal rat ventricular myocytes (NRVCs). KLF15 overexpression mediated by adeno-associated virus significantly abrogated the ischemia-induced cardiac dysfunction, increased the survival rate and reduced infarct size after MI. Meanwhile, KLF15 overexpression dramatically reduced the myocardial apoptosis, regulated apoptosis-related genes such as Bcl2 and Bax, diminished the activities of caspase-9/3 and inactivated p38/MAPK signaling in the border zone. Similar results were observed in NRVCs exposed to hypoxia. Conclusions We demonstrated for the first time that KLF15 overexpression could reduce cardiomyocyte apoptosis and improve cardiac dysfunction in MI mice at least partially by inhibiting p38/MAPK signaling pathway.

Interactions between noncoding RNAs as epigenetic regulatory mechanisms in cardiovascular diseases

Cardiovascular diseases (CVDs) represent the foremost cause of mortality in the United States and worldwide. It is estimated that CVDs account for approximately 17.8 million deaths each year. Despite the advances made in understanding cellular mechanisms and gene mutations governing the pathophysiology of CVDs, they remain a significant cause of mortality and morbidity. A major segment of mammalian genomes encodes for genes that are not further translated into proteins. The roles of the majority of such noncoding ribonucleic acids (RNAs) have been puzzling for a long time. However, it is becoming increasingly clear that noncoding RNAs (ncRNAs) are dynamically expressed in different cell types and have a comprehensive selection of regulatory roles at almost every step involved in DNAs, RNAs and proteins. Indeed, ncRNAs regulate gene expression through epigenetic interactions, through direct binding to target sequences, or by acting as competing endogenous RNAs. The profusion of ncRNAs in the cardiovascular system suggests that they may modulate complex regulatory networks that govern cardiac physiology and pathology. In this review, we summarize various functions of ncRNAs and highlight the recent literature on interactions between ncRNAs with an emphasis on cardiovascular disease regulation. Furthermore, as the broad-spectrum of ncRNAs potentially establishes new avenues for therapeutic development targeting CVDs, we discuss the innovative prospects of ncRNAs as therapeutic targets for CVDs.

Clinical significance of the long non-coding RNA NEAT1/miR-129-5p axis in the diagnosis and prognosis for patients with chronic heart failure

Chronic heart failure (CHF) is the leading cause of death worldwide. The regulatory interactions of long non-coding RNA (lncRNAs) and microRNAs (miRs) have important roles in multiple diseases. However, the clinical significance of the nuclear-enriched abundant transcript 1 (NEAT1)/miR-129-5p axis in CHF has remained elusive. The present study explored whether the NEAT1/miR-129-5p axis may be a suitable diagnostic and prognostic marker for CHF. The expression of lncRNA NEAT1 and miR-129-5p in the serum of patients with CHF was analyzed by reverse transcription-quantitative PCR. Furthermore, inter-indicator correlations were assessed by Pearson correlation coefficient analysis. Receiver operating characteristic (ROC) curves were generated to evaluate the ability of NEAT1, miR-129-5p and brain natriuretic peptide (BNP) to identify patients with CHF. The prognostic value of the NEAT1/miR-129-5p axis was analyzed by drawing Kaplan-Meier survival curves and by Cox logistic regression analysis. Baseline data were not significantly different between CHF (n=70) and control subjects (n=62). The serum level of NEAT1 was increased and the expression level of miR-129-5p was decreased in patients with CHF (all P<0.001). The ROC curves suggested that serum NEAT1 and miR-129-5p were of diagnostic value in patients with CHF and the combined diagnostic accuracy of NEAT1, miR-129-5p and BNP was significantly improved. Kaplan-Meier and multivariate Cox regression analysis suggested that low NEAT1 and high miR-129-5p were able to predict overall survival of patients with CHF (all P<0.01). In conclusion, the present study indicated that patients with CHF had increased NEAT1 and decreased miR-129-5p expression. The deregulated NEAT1/miR-129-5p axis may provide novel non-invasive biomarkers for the diagnosis and prognosis of CHF.