Knockdown of long non-coding RNA MEG3 protects H9c2 cells from hypoxia-induced injury by targeting microRNA-183

Epigallocatechin gallate prevents cardiomyocytes from pyroptosis through lncRNA MEG3/TAF15/AIM2 axis in myocardial infarction

BACKGROUND

( -)-Epigallocatechin-3-gallate (EGCG), a bioactive polyphenol isolated from green tea, has recently garnered attention for its potential protective role against acute myocardial infarction (MI) via inhibiting inflammation. Herein, we tested whether EGCG participates in modulating cardiac ischemia reperfusion-induced injury and elucidate its potential mechanisms.

METHODS

To induce MI in mice, we employed coronary artery ligation, while cell models utilized oxygen glucose deprivation/re-oxygenation (OGD/R)-treated HL-1 cells. TTC, HE and Massion staining evaluated the pathological changes of heart tissues. Besides, RNA-pull down and RIP assays analyzed the interactions of MEG3/TAF15 and AIM2 mRNA/TAF15. FISH associated with immunofiuorescence (IF) double staining was conducted to measure the co-localization of MEG3 and TAF15.

RESULTS

In vitro and in vivo evidence supported that EGCG treatment improved cardiomyocytes viability while inhibiting the expressions of AIM2, C-caspase-1, ASC, GSDMD-N, IL-18 and IL-1β. Knockdown of MEG3 intensified EGCG's therapeutic effects both in vitro and in vivo. LncRNA MEG3 and AIM2 mRNA interacted with TAF15, and MEG3, in turn, promoted the stability of AIM2 mRNA through regulating TAF15. Overexpression of TAF15 reversed the promoting effect of EGCG and MEG3 knockdown on cell viability, and the inhibiting effect on cell pyroptosis.

CONCLUSION

EGCG protected cardiomyocytes from pyroptosis by the MEG3/TAF15/AIM2 axis, indicating EGCG as a potential novel therapeutic strategy for managing MI.

Apoptosis and long non-coding RNAs: Focus on their roles in Heart diseases

Heart disease is one of the principal death reasons around the world and there is a growing requirement to discover novel healing targets that have the potential to avert or manage these illnesses. On the other hand, apoptosis is a strongly controlled, cell removal procedure that has a crucial part in numerous cardiac problems, such as reperfusion injury, MI (myocardial infarction), consecutive heart failure, and inflammation of myocardium. Completely comprehending the managing procedures of cell death signaling is critical as it is the primary factor that influences patient mortality and morbidity, owing to cardiomyocyte damage. Indeed, the prevention of heart cell death appears to be a viable treatment approach for heart illnesses. According to current researches, a number of long non-coding RNAs cause the heart cells death via different methods that are embroiled in controlling the activity of transcription elements, the pathways that signals transmission within cells, small miRNAs, and the constancy of proteins. When there is too much cell death in the heart, it can cause problems like reduced blood flow, heart damage after restoring blood flow, heart disease in diabetics, and changes in the heart after reduced blood flow. Therefore, studying how lncRNAs control apoptosis could help us find new treatments for heart diseases. In this review, we present recent discoveries about how lncRNAs are involved in causing cell death in different cardiovascular diseases.

The multifaceted biology of lncR-Meg3 in cardio-cerebrovascular diseases

Cardio-cerebrovascular disease, related to high mortality and morbidity worldwide, is a type of cardiovascular or cerebrovascular dysfunction involved in various processes. Therefore, it is imperative to conduct additional research into the pathogenesis and new therapeutic targets of cardiovascular and cerebrovascular disorders. Long non-coding RNAs (lncRNAs) have multiple functions and are involved in nearly all cellular biological processes, including translation, transcription, signal transduction, and cell cycle control. LncR-Meg3 is one of them and is becoming increasingly popular. By binding proteins or directly or competitively binding miRNAs, LncR-Meg3 is involved in apoptosis, inflammation, oxidative stress, endoplasmic reticulum stress, epithelial-mesenchymal transition, and other processes. Recent research has shown that LncR-Meg3 is associated with acute myocardial infarction and can be used to diagnose this condition. This article examines the current state of knowledge regarding the expression and regulatory function of LncR-Meg3 in relation to cardiovascular and cerebrovascular diseases. The abnormal expression of LncR-Meg3 can influence neuronal cell death, inflammation, apoptosis, smooth muscle cell proliferation, etc., thereby aggravating or promoting the disease. In addition, we review the bioactive components that target lncR-Meg3 and propose some potential delivery vectors. A comprehensive and in-depth analysis of LncR-Meg3’s role in cardiovascular disease suggests that targeting LncR-Meg3 may be an alternative therapy in the near future, providing new options for slowing the progression of cardiovascular disease.

Knockdown of lncRNA SNHG16 attenuates myocardial ischemia‑reoxygenation injury via targeting miR‑183/FOXO1 axis

Accumulating evidence shows that long non-coding RNAs (lncRNAs) are widely involved in cellular processes of myocardial ischemia/reperfusion (I/R). The present study investigated the functions of lncRNA SNHG16 in myocardial I/R and the mechanism mediated by SNHG16. The myocardial I/R rat and cell model and hypoxia/reoxygenation injury (H/R) models of H9C2 cardiomyocytes were established to detect the expression of SNHG16. Cell Counting Kit-8, flow cytometric and western blot assays were conducted to detect cell viability, apoptosis and protein expression. Myocardial cell apoptosis was assessed by TUNEL staining. Dual-luciferase gene reporter was applied to determine the interaction between the molecules. The expressions of SNHG16 were upregulated in myocardial I/R injury models. Inhibition of SNHG16 relieved myocardial I/R injury in vivo and in vitro silencing of SNHG16 alleviated H/R induced cardiomyocyte apoptosis. To explore the regulatory mechanism, it was discovered that SNHG16 directly interacted with miR-183, while forkhead box O1 (FoxO1) was a target of microRNA (miR)-183. Findings from rescue assays revealed that miR-183 inhibitor and upregulation of FOXO1 can rescue the effect of sh-SNHG16 on H/R-induced cardiomyocyte apoptosis. The results indicated that the lncRNA SNHG16/miR-183/FOXO1 axis exacerbated myocardial cell apoptosis in myocardial I/R injury, suggesting SNHG16 as a potential therapeutic target for myocardial I/R injury.

Early-Onset Neonatal Sepsis: Inflammatory Biomarkers and MicroRNA as Potential Diagnostic Tools in Preterm Newborns

Mortality and morbidity of newborns with sepsis can be improved by early and accurate diagnosis and targeted therapy. To evaluate the early molecular events associated with inflammation and infection, we evaluated markers of endothelial activation and injury and circulating plasma miRNAs in preterm newborns with sepsis. The study group consisted of newborns with gestational age ≤ 32 weeks, with culture-positive early-onset neonatal sepsis (sepsis group, N = 8), and as a control group, we enrolled newborns without sepsis (control group, N = 12). Soluble markers of inflammation were measured using Luminex-based multiplex assay. Platelet-free plasma RNA was used to construct the library for miRNA sequencing analysis. Normalized counts were calculated and used to measure differential expression of individual detected miRNAs. We found a significant increase of interleukin 18 (IL-18) in the cord blood of the sepsis group (mean ± SEM, 104.7 ± 30.4 pg/ml vs 52.7 ± 5.6 pg/ml, P = 0.02). In peripheral blood of sepsis group patients, we found a significant increase of VEGF-A compared to controls (196.0 ± 70.5 pg/ml vs 59.6 ± 8.5 pg/ml, P = 0.02). In the cord blood plasma, eight miRNAs had significantly differential expression (P < 0.05), four miRNAs were up-regulated and four miRNAs down-regulated. In peripheral blood plasma, all nine miRNAs with significant differential expression were up-regulated. In conclusion, in early-onset neonatal sepsis, IL-18 and VEGF-A might be considered in diagnostic workup. Early-onset sepsis in preterm newborns is associated with significant changes in the circulating miRNA pattern.

Impact of the Main Cardiovascular Risk Factors on Plasma Extracellular Vesicles and Their Influence on the Heart's Vulnerability to Ischemia-Reperfusion Injury

The majority of cardiovascular deaths are associated with acute coronary syndrome, especially ST-elevation myocardial infarction. Therapeutic reperfusion alone can contribute up to 40 percent of total infarct size following coronary artery occlusion, which is called ischemia-reperfusion injury (IRI). Its size depends on many factors, including the main risk factors of cardiovascular mortality, such as age, sex, systolic blood pressure, smoking, and total cholesterol level as well as obesity, diabetes, and physical effort. Extracellular vesicles (EVs) are membrane-coated particles released by every type of cell, which can carry content that affects the functioning of other tissues. Their role is essential in the communication between healthy and dysfunctional cells. In this article, data on the variability of the content of EVs in patients with the most prevalent cardiovascular risk factors is presented, and their influence on IRI is discussed.

Long non-coding RNA MEG3 promotes cisplatin-induced nephrotoxicity through regulating AKT/TSC/mTOR-mediated autophagy

Cis-Diamminedichloroplatinum (II) (DDP)-induced nephrotoxicity (DDPIN) may cause irreversible renal injury associated with high morbidity and mortality. Current standard therapies have not achieved satisfactory clinical outcomes due to unclear molecular and cellular mechanisms. Therefore, exploring potential therapies on DDPIN represents an urgent medical need. Present study characterized the role of lncRNA maternally expressed gene 3 (lnc-MEG3) in the pathogenesis of DDPIN. In both in vitro and in murine models of DDP-induced nephrotoxicity, lnc-MEG3 exacerbated DDPIN by negatively regulating miRNA-126 subsequently causing a decreased AKT/TSC/mTOR-mediated autophagy. By silencing lnc-MEG3 or incorporating miRNA-126 mimetics, the proliferation and migration of DDP-treated cells were restored. In vivo, we identified Paeonol to alleviate DDPIN by the inhibition of lnc-MEG3. Taken together, lnc-MEG3 represents a novel therapeutic target for DDPIN and Paeonol may serve as a promising treatment by inhibiting lnc-MEG3 and its related signaling pathways.

Se alleviates homocysteine-induced fibrosis in cardiac fibroblasts via downregulation of lncRNA MEG3

Selenium (Se) is considered to have antioxidant properties, which are beneficial for heart condition. Hyperhomocysteinemia (HHCY) has been suggested to potentially lead to heart failure and is characterized by cardiac fibrosis; however, investigation on the role of Se and HHCY in cardiac fibrosis is rare. Since previous studies demonstrated the important role of the long non-coding RNA maternally expressed 3 (MEG3) in some heart diseases, the present study aimed to determine how Se and MEG3 might exert regulatory effects on HCY-induced fibrosis in cardiac fibroblasts (CFs). Mouse CFs were isolated and treated with HCY and Se. The expression of α-smooth muscle actin (α-SMA), collagen I and III was detected by western blotting to reflect CF fibrosis. Reverse transcription-quantitative PCR was performed to determine the expression levels of MEG3. Inflammation and oxidative stress responses were analyzed by measuring TNF-α, IL-1β (ELISA) and reactive oxygen species levels (using a commercial kit), respectively. Cell Counting Kit-8 was used to evaluate CF proliferation. Total and phosphorylated (p) expression of janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) was evaluated by western blotting. CFs were transfected with adenovirus expressing MEG3 short-hairpin RNA to knock down MEG3 expression. Se treatment downregulated the expression level of MEG3 in HCY-stimulated CFs, whilst inhibiting the inflammatory and oxidative stress response. Furthermore, Se inhibited the increased proliferation of CFs following HCY treatment. In addition, MEG3-knockdown in CFs could improve fibrosis caused by HCY. Furthermore, the ratios of p-JAK2/JAK2 and p-STAT3/STAT3 were decreased following treatment with Se or MEG3 silencing. Taken together, the findings from the present study suggested that Se may alleviate cardiac fibrosis by downregulating the expression of MEG3 and reducing the inflammatory and oxidative stress response in CFs. This suggests that Se may be a potential therapeutic option for treating cardiac fibrosis in the future.

The Key Lnc (RNA)s in Cardiac and Skeletal Muscle Development, Regeneration, and Disease

Non-coding RNAs (ncRNAs) play a key role in the regulation of transcriptional and epigenetic activity in mammalian cells. Comprehensive analysis of these ncRNAs has revealed sophisticated gene regulatory mechanisms which finely tune the proper gene output required for cellular homeostasis, proliferation, and differentiation. However, this elaborate circuitry has also made it vulnerable to perturbations that often result in disease. Among the many types of ncRNAs, long non-coding RNAs (lncRNAs) appear to have the most diverse mechanisms of action including competitive binding to miRNA targets, direct binding to mRNA, interactions with transcription factors, and facilitation of epigenetic modifications. Moreover, many lncRNAs display tissue-specific expression patterns suggesting an important regulatory role in organogenesis, yet the molecular mechanisms through which these molecules regulate cardiac and skeletal muscle development remains surprisingly limited. Given the structural and metabolic similarities of cardiac and skeletal muscle, it is likely that several lncRNAs expressed in both of these tissues have conserved functions in establishing the striated muscle phenotype. As many aspects of regeneration recapitulate development, understanding the role lncRNAs play in these processes may provide novel insights to improve regenerative therapeutic interventions in cardiac and skeletal muscle diseases. This review highlights key lncRNAs that function as regulators of development, regeneration, and disease in cardiac and skeletal muscle. Finally, we highlight lncRNAs encoded by imprinted genes in striated muscle and the contributions of these loci on the regulation of gene expression.

Role of long non-coding RNAs in adipogenesis: State of the art and implications in obesity and obesity-associated diseases

Obesity is an evolutionary, chronic, and relapsing disease that consists of a pathological accumulation of adipose tissue able to increase morbidity for high blood pressure, type 2 diabetes, metabolic syndrome, and obstructive sleep apnea in adults, children, and adolescents. Despite intense research over the last 20 years, obesity remains today a disease with a complex and multifactorial etiology. Recently, long non-coding RNAs (lncRNAs) are emerging as interesting new regulators as different lncRNAs have been found to play a role in early and late phases of adipogenesis and to be implicated in obesity-associated complications onset. In this review, we discuss the most recent advances on the role of lncRNAs in adipocyte biology and in obesity-associated complications. Indeed, more and more researchers are focusing on investigating the underlying roles that these molecular modulators could play. Even if a significant number of evidence is correlation-based, with lncRNAs being differentially expressed in a specific disease, recent works are now focused on deeply analyzing how lncRNAs can effectively modulate the disease pathogenesis onset and progression. LncRNAs possibly represent new molecular markers useful in the future for both the early diagnosis and a prompt clinical management of patients with obesity.

Long Non-coding RNA: A Key Regulator in the Pathogenesis of Diabetic Cardiomyopathy

In recent years, diabetes mellitus has become a global issue with increasing incidence rate worldwide. Diabetic cardiomyopathy (DCM), one of the important complications of diabetes, refers to patients with type 1 and type 2 diabetes who have ventricular hypertrophy, fibrosis and even diastolic dysfunction. The pathogenesis of DCM is related to oxidative stress, inflammatory response, apoptosis, autophagy, myocardial fibrosis and, diabetic microangiopathy. Long non-coding RNAs (lncRNA) is a non-coding RNA with a length longer than 200 nucleotides which lack the ability of protein coding. With the development of molecular technology, massive evidence demonstrates that lncRNA play a critical role in the molecular mechanism of DCM. Moreover, it can also be used as potential diagnostic markers for DCM. In this review, we intend to summarize the pathological roles and molecular mechanism of lncRNA in the progression of diabetic cardiomyopathy, which may provide promising diagnosis and treatment strategies for DCM.

Recent advances in the regulation of ABCA1 and ABCG1 by lncRNAs

Coronary heart disease (CHD) with atherosclerosis is the leading cause of death worldwide. ABCA1 and ABCG1 promote cholesterol efflux to suppress foam cell generation and reduce atherosclerosis development. Long noncoding RNAs (lncRNAs) are emerging as a unique group of RNA transcripts that longer than 200 nucleotides and have no protein-coding potential. Many studies have found that lncRNAs regulate cholesterol efflux to influence atherosclerosis development. ABCA1 is regulated by different lncRNAs, including MeXis, GAS5, TUG1, MEG3, MALAT1, Lnc-HC, RP5-833A20.1, LOXL1-AS1, CHROME, DAPK1-IT1, SIRT1 AS lncRNA, DYNLRB2-2, DANCR, LeXis, LOC286367, and LncOR13C9. ABCG1 is also regulated by different lncRNAs, including TUG1, GAS5, RP5-833A20.1, DYNLRB2-2, ENST00000602558.1, and AC096664.3. Thus, various lncRNAs are associated with the roles of ABCA1 and ABCG1 on cholesterol efflux in atherosclerosis regulation. However, some lncRNAs play dual roles in ABCA1 expression and atherosclerosis, and the functions of some lncRNAs in atherosclerosis have not been investigated in vivo. In this article, we review the roles of lncRNAs in atherosclerosis and focus on new insights into lncRNAs associated with the roles of ABCA1 and ABCG1 on cholesterol efflux and the potential of these lncRNAs as novel therapeutic targets in atherosclerosis.

Inorganic arsenic influences cell apoptosis by regulating the expression of MEG3 gene

Arsenic is a wildly distributed carcinogen in the environment. Arsenic-induced apoptosis has been extensively studied in therapeutics and toxicology. LncRNA MEG3 has been extensively studied as apoptosis regulatory gene in recent years. However, it stays unclear regarding how the mechanism of MEG3 regulates arsenic-induced apoptosis. Our focus was to explore the effects of MEG3 on arsenic-induced apoptosis. MTS assay was used to test cell viability, and qRT-PCR was for the examination of gene expressions. The effect of the apoptosis and necrosis after knockdown MEG3 was detected with double staining. Our results demonstrated that MEG3 expression was positively correlated with the concentration of three arsenic species (inorganic arsenic (iAs), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)) (p < 0.05). The ability of iAs to induce MEG3 expression was much higher compared with that induced by MMA and DMA. In addition, our experiments confirmed that MEG3 knockdown increased cell viability and arsenic-induced apoptosis, but cell viability decreased after iAs treatment. Moreover, LncRNA MEG3 regulated apoptosis via down-regulate API5 while up-regulate CASP7, CCND3 and APAF1. It is further proved that arsenic-induced apoptosis increased after the knockdown of MEG3, which regulates these genes. These findings provide experimental evidence and possible mechanisms for subsequent research on the effects of arsenic on health.

Long non‑coding RNA MEG3 knockdown alleviates hypoxia‑induced injury in rat cardiomyocytes via the miR‑325‑3p/TRPV4 axis

Acute myocardial infarction (AMI) is a common cardiac disease. Long non-coding RNA maternally expressed 3 (MEG3) is associated with cellular processes in numerous complicated diseases, including AMI. However, the mechanism underlying MEG3 in myocardial hypoxia is not completely understood. The present study aimed to investigate the underlying mechanism of MEG3 in myocardial hypoxia. The expression levels of hypoxia-inducible factor 1α (HIF1α), MEG3, microRNA (miR)-325-3p, and transient receptor potential cation channel subfamily V member 4 (TRPV4) in hypoxia-treated H9c2 cells were detected via reverse transcription-quantitative PCR. The protein expression levels of HIF1α, Bcl-2, Bax, cleaved caspase-3 and TRPV4 were detected via western blotting. Cell viability and apoptosis were assessed by performing an MTT assay and flow cytometry, respectively. Lactate dehydrogenase (LDH) release was monitored by conducting an LDH determination assay. The Dual-Luciferase reporter assay was performed to verify the targeted relationship between miR-325-3p and MEG3 or TRPV4. The expression levels of MEG3 and TRPV4 were significantly increased, whereas miR-325-3p expression levels were significantly decreased in hypoxic H9c2 cells compared with normoxic H9c2 cells. In addition, miR-325-3p was downregulated by MEG3 compared with the vector group, and miR-325-3p targeted TRPV4 in hypoxia-treated H9c2 cells. The results indicated that MEG3 knockdown attenuated hypoxia-stimulated injury in H9c2 cells by regulating miR-325-3p. TRPV4 knockdown also mitigated hypoxia-induced injury in H9c2 cells via miR-325-3p. Furthermore, compared with the vector group, MEG3 increased TRPV4 expression in hypoxia-treated H9c2 cells by sponging miR-325-3p. Collectively, the results of the present study suggested that MEG3 modulated TRPV4 expression to aggravate hypoxia-induced injury in rat cardiomyocytes by sponging miR-325-3p.

MicroRNA-219-5p participates in cyanotic congenital heart disease progression by regulating cardiomyocyte apoptosis

MicroRNAs (miRs) play important roles in the protection against and development of congenital heart disease (CHD). However, the role and potential mechanisms of miR-219-5p in cyanotic CHD remains unclear. Reverse transcription-quantitative PCR (RT-qPCR) was used to measure miR-219-5p levels in cyanotic CHD and hypoxia-induced H9C2 cells. Dual luciferase reporter gene assay was used to confirm whether liver receptor homolog-1 (LRH-1) was a direct target of miR-219-5p. miR-219-5p inhibitor and LRH-1-small interfering RNA were transfected into H9C2 cells under hypoxic conditions to investigate the role of miR-219-5p in hypoxia-induced H9C2 cells. Subsequently, cell viability was detected using an MTT assay and cell apoptosis was detected using flow cytometry. In addition, RT-qPCR and western blotting assays were performed to detect the mRNA and protein expression of LRH-1, cyclin D1 and β-catenin, respectively. The data showed that miR-219-5p expression was higher in patients with cyanotic CHD compared with patients with acyanotic CHD gradually increased in H9C2 cells with prolonged hypoxia time. Dual luciferase reporter assay results showed that LRH-1 was a direct target gene of miR-219-5p. Inhibition of miR-219-5p reversed hypoxia-induced cell viability reduction and attenuated hypoxia-induced cell apoptosis. In addition, hypoxia induction inhibited the expression of LRH-1, cyclin D1 and β-catenin, which was reversed by miR-219-5p inhibitor. However, LRH-1 downregulation reversed the miR-219-5p inhibitor enhanced cell viability, decreased cell apoptosis and increased expression of LRH-1, cyclin D1 and β-catenin in hypoxia-treated cardiomyocytes. The present results demonstrated that downregulation of miR-219-5p promoted the expression of the LRH-1/Wnt/β-catenin signaling pathway-associated components, reduced cardiomyocyte apoptosis and increased cell growth under hypoxic conditions. miR-219-5p may be a potential therapeutic target for cyanotic CHD therapy.

The roles of long noncoding RNAs in myocardial pathophysiology

Long noncoding RNAs (lncRNAs), more than 200 nt in length, are functional molecules found in various species. These lncRNAs play a vital role in cell proliferation, differentiation, and degeneration and are also involved in pathophysiological processes of cancer and neurodegenerative, autoimmune, and cardiovascular diseases (CVDs). In recent years, emerging challenges for intervention studies on ischemic heart diseases have received much attention. LncRNAs have a key function in the alleviation of myocardial infarction (MI) injury and myocardial ischemia–reperfusion injury. During cardiac hypertrophy (CH) and fibrosis, cardiac cells undergo structural changes and become dysfunctional due to the effects of neurohormonal factors. LncRNAs may serve as important therapeutic targets that promote cardiac remodeling and then retard the development of heart failure (HF). In addition, studies on the roles and mechanisms of action of lncRNAs participating in cardiac pathophysiology via other factors have become the focus of research worldwide. Here, we review the current knowledge on various lncRNAs and their functions in cardiac biology, particularly concentrating on ischemic heart disease, CH, and cardiac fibrosis. We next discuss the predictive value of lncRNAs as diagnostic biomarkers of CVDs.

miR‑183‑5p attenuates cerebral ischemia injury by negatively regulating PTEN

Cerebral ischemia is a common cerebrovascular disease caused by the occlusion of a cerebral blood vessel. MicroRNAs (miRNAs/miRs) are emerging regulators of various human diseases, including cerebral ischemia. Upregulation of miR‑183‑5p has been reported to alleviate liver injury induced by ischemia‑reperfusion (I/R). However, the effect of miR‑183‑5p on cerebral ischemia injury remains unknown. The present study evaluated the effects of miR‑183‑5p on ischemia injury using ischemic models of mouse brains exposed to transient middle cerebral artery occlusion and Neuro‑2A (N2A) neuroblastoma cells exposed to oxygen‑glucose‑deprivation (OGD) and subsequently reoxygenated. Ischemia was evaluated in mice using neurological function scores, cerebral edema, 2,3,5‑triphenyltetrazoliumchloride, Nissl and Fluoro‑Jade B staining assays. In addition, miR‑183‑5p expression, N2A cell viability and the expression levels of apoptosis‑associated proteins were detected by quantitative PCR, Cell Counting Kit‑8 assay, flow cytometry and western blotting. The association between miR‑183‑5p and phosphatase and tensin homolog (PTEN) was also confirmed by a luciferase reporter assay. The results revealed that miR‑183‑5p expression was decreased and brain damage was increased in ischemic mice compared with the sham group. Additionally, miR‑183‑5p levels were reduced, and apoptosis was increased in N2A cells exposed to ischemia compared with the control group. Following transfection with agomiR‑183‑5p, cerebral ischemic injury and apoptosis levels were reduced in the in vivo I/R stroke model and OGD‑induced N2A cells. In addition, PTEN was determined to be a target of miR‑183‑5p following elucidation of a direct binding site. Overexpression of PTEN reversed the miR‑183‑5p‑induced N2A cell apoptosis inhibition and survival after OGD. The results of the present study suggested that miR‑183‑5p reduced ischemic injury by negatively regulating PTEN, which may aid the development of a novel therapeutic strategy for cerebral ischemia.

Dysregulations of MicroRNA and Gene Expression in Chronic Venous Disease

Chronic venous disease (CVD) is a vascular disease of lower limbs with high prevalence worldwide. Pathologic features include varicose veins, venous valves dysfunction and skin ulceration resulting from dysfunction of cell proliferation, apoptosis and angiogenesis. These processes are partly regulated by microRNA (miRNA)-dependent modulation of gene expression, pointing to miRNA as a potentially important target in diagnosis and therapy of CVD progression. The aim of the study was to analyze alterations of miRNA and gene expression in CVD, as well as to identify miRNA-mediated changes in gene expression and their potential link to CVD development. Using next generation sequencing, miRNA and gene expression profiles in peripheral blood mononuclear cells of subjects with CVD in relation to healthy controls were studied. Thirty-one miRNAs and 62 genes were recognized as potential biomarkers of CVD using DESeq2, Uninformative Variable Elimination by Partial Least Squares (UVE-PLS) and ROC (Receiver Operating Characteristics) methods. Regulatory interactions between potential biomarker miRNAs and genes were projected. Functional analysis of microRNA-regulated genes revealed terms closely related to cardiovascular diseases and risk factors. The study shed new light on miRNA-dependent regulatory mechanisms involved in the pathology of CVD. MicroRNAs and genes proposed as CVD biomarkers may be used to develop new diagnostic and therapeutic methods.

MiR-183-5p protects rat hearts against myocardial ischemia/reperfusion injury through targeting VDAC1

MicroRNAs have been reported to be implicated in myocardial ischemia/reperfusion (I/R) injury. The purpose of this study was to investigate the effect of miR-183-5p on I/R injury. Overexpression of miR-183-5p by agomiR transfection alleviated cardiac dysfunction and significantly reduced the infarct size in rats with myocardial I/R. MiR-183-5p also alleviated myocardial apoptosis with reduced apoptotic cells and lower levels of apoptosis associated proteins. in vitro experiments were conducted on rat H9c2 cells treated with anoxia/reoxygenation (A/R). Annexin V/propidium iodide (PI) staining and flow cytometry reported that the ratio of apoptotic cells decreased by miR-183-5p transfection before A/R treatment. Moreover, according to binding sequence prediction and Dual luciferase reporter assay, we explored that voltage-dependent anion channel 1 (VDAC1), which aggravates myocardial injury and apoptosis reported in our former research, was a target of miR-183-5p. In conclusion, miR-183-5p can efficiently attenuate I/R injury and miR-183-5p may exert its effect through repressing VDAC1 expression.

Interactions Among Regulatory Non-coding RNAs Involved in Cardiovascular Diseases

Non-coding RNAs (ncRNAs) are important regulatory players in human cells that have been shown to modulate different cellular processes and biological functions through controlling gene expression, being also involved in pathological conditions such as cardiovascular diseases. Among them, long non-coding RNAs (lncRNAs) and circular (circRNAs) could act as competing endogenous RNAs (ceRNAs) sequestering other ncRNAs. This entangled network of interactions has been reported to trigger the decay of the targeted ncRNAs having important roles in gene regulation. Growing evidences have been demonstrated that the regulatory mechanism underlying the crosstalk between different ncRNA species, namely lncRNAs, circRNAs and miRNAs has also an important role in the pathophysiological processes of cardiovascular diseases. In this chapter, the main regulatory relationship among lncRNAs, circRNAs and miRNAs were summarized and their role in the control and development of cardiovascular diseases was highlighted.

LncRNA nuclear-enriched abundant transcript 1 regulates hypoxia-evoked apoptosis and autophagy via mediation of microRNA-181b

Nuclear-enriched abundant transcript 1 (NEAT1), a vital long noncoding RNA (lncRNA), exhibits the functions in disparate cancers. Nevertheless, the influences of NEAT1 in congenital heart disease (CHD) remain unreported. The research delves into whether NEAT1 affects H9c2 cells apoptosis and autophagy under the hypoxia condition. Overexpressed NEAT1 vector was transfected into H9c2 cells; then, functions of NEAT1 in cell viability, apoptosis, autophagy, PI3K/AKT/mTOR and JAK1/STAT3 pathways were detected in H9c2 cells under hypoxia condition. Expression of NEAT1 and miR-181b in hypoxia and blood samples from CHD was evaluated. After miR-181b inhibitor transfection, functions of miR-181b repression in the above-mentioned cell behavior and PI3K/AKT/mTOR and JAK1/STAT3 pathways were reassessed. Overexpressed NEAT1 clearly allayed hypoxia-triggered H9c2 cells apoptosis and autophagy. The decreased NEAT1 and miR-181b were showcased in hypoxia and blood samples from CHD; meanwhile, elevated miR-181b evoked by overexpressed NEAT1 was observed in hypoxia-managed H9c2 cells. More importantly, miR-181b inhibition obviously overturned the influences of NEAT1 in hypoxia-affected H9c2 cells apoptosis and autophagy. Besides, overexpressed NEAT1 facilitated PI3K/AKT/mTOR and JAK1/STAT3 activations via enhancing miR-181b. The research exposed that NEAT1 eased hypoxia-triggered H9c2 cells apoptosis and autophagy by expediting PI3K/AKT/mTOR and JAK1/STAT3 pathways via elevating miR-181b.

Inhibition of microRNA-183 expression resists human umbilical vascular endothelial cells injury by upregulating expression of IRS1

Our study aims to investigate the effect of microRNA-183 (miR-183) on human umbilical vascular endothelial cells (HUVECs) injury by targeting IRS1. HUVECs injury was induced by oxidized low-density lipoprotein (ox-LDL). HUVECs were grouped so as to explore the role of ox-LDL and miR-183 in HUVECs injury, with the expression of miR-183 and IRS1 detected. Additionally, the related factors of oxidative stress and inflammation, as well as angiogenesis ability, proliferation, cell cycle, apoptosis, invasion, and migration abilities were also measured. Ox-LDL treatment could decrease the activity of HUVECs, increase the level of oxidative stress and inflammation, and induce the HUVECs injury. miR-183 could inhibit the expression of IRS1. The inhibition of miR-183 expression in ox-LDL-induced HUVECs injury could enhance cell activity, inhibit inflammatory level, and thus resist cell injury. Low expression of IRS1 could reverse the inhibition of miR-183 on HUVECs injury. This study highlights that inhibition of miR-183 expression may resist HUVECs injury by upregulating expression of IRS1.

Cardio-protective effects of salvianolic acid B on oxygen and glucose deprivation (OGD)-treated H9c2 cells

The morphological feature of apoptosis is induced by oxygen and glucose deprivation (OGD) in cardiomyocytes H9c2 cells. Salvianolic acid B (Sal-B) has been studied in several pathological progresses, whereas it is still unclear whether maternally expressed gene 3 (MEG3) is an intermediate regulator during this progress. After pre-incubation with Sal-B and stimulation with OGD, viability and apoptosis of were examined in MEG3-overexpressed H9c2 cells. Cyclin D1, apoptosis-correlated proteins and regulators of signalling pathways were quantified with Western blot assay. MEG3 was detected by quantitative reverse transcription PCR (qRT-PCR). Sal-B was implicated in the enhancement of cell viability and suppression of apoptosis in OGD-treated H9c2 cells by repressing MEG3. In addition, MEG3 overexpression exerted an inhibitory effect on murine double minute 2 (MDM2) expression while aggrandized p53 expression in OGD-treated H9c2 cells which were pre-incubated with Sal-B. Furthermore, MEG3 overexpression abolished the up-regulative effect of Sal-B on phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) in OGD-treated H9c2 cells. These results indicated that cardio-protective function of Sal-B might be ascribed to its down-regulatory property on MEG3 expression which hence blocks p53 and triggers AMPK activation in OGD-treated cells.

Long noncoding RNA MEG3 deteriorates inflammatory damage by downregulating microRNA-101a

Valvulopathy is a familiar heart disease, which fearfully harms the health of the body. We studied the effects and mechanism of long noncoding RNA maternally expressed gene 3 (lncMEG3) on MVICs cell in inflammatory damage. Cell Counting Kit-8 and flow cytometry were respectively used to detect the effect of tumor necrosis factor α (TNF-α), MEG3 and microRNA (miR)-101a on cell viability and apoptosis. Moreover, MEG3 and miR-101a expression were changed by cell transfection and investigated by reverse transcription-quantitative polymerase chain reaction. Furthermore, Western blot was used to investigate the levels of Bax, pro-caspase-3, cleaved-caspase-3, pro-caspase-9, cleaved-caspase-9, interleukin (IL)-1β, IL-6 and related-proteins of cell pathways. Otherwise, the levels of IL-1β and IL-6 were also investigated by enzyme-linked immunosorbent assay kit. Reactive oxygen species (ROS) was examined by ROS assay. We found TNF-α caused inflammatory damage and upregulated MEG3. MEG3 was overexpressed and silenced in cells. Besides, MEG3 deteriorated inflammatory damage. Furthermore, MEG3 negatively regulated miR-101a and miR-101a mimic could reverse the effect of pc-MEG3. Besides, MEG3 enhanced the JNK and NF-κB pathways by downregulating miR-101a. In conclusion, MEG3 deteriorated cell inflammatory damage by downregulating miR-101a via JNK and NF-κB pathways.

Long non-coding RNA MEG3 knockdown attenuates endoplasmic reticulum stress-mediated apoptosis by targeting p53 following myocardial infarction

Mounting evidence has indicated that long non-coding RNA maternally expressed gene 3 (lncRNA MEG3) regulates cell apoptosis, and is involved in a variety of diseases. However, its exact role in myocardial infarction (MI) has not been fully elucidated. In the present study, we firstly observed that the expression levels of the lncRNA MEG3 in infarct hearts and hypoxic neonatal mice ventricular myocytes (NMVMs) were up-regulated by quantitative real-time PCR (qRT-PCR). Then, we knocked down lncRNA MEG3 by lentiviral delivery in the myocardial border region following multipoint injection. Following 28 days of MI, the lncRNA MEG3 knockdown mice indicated better cardiac function, and less cardiac remodelling by ultrasonic cardiogram and histological analysis. In addition, we indicated that lncRNA MEG3 knockdown reduced myocyte apoptosis and reactive oxygen species production in MI mice model and hypoxic NMVMs. Furthermore, we revealed that knockdown of lncRNA MEG3 protected against endoplasmic reticulum stress (ERS)-mediated myocardial apoptosis including the induction of PERK-eIF2α and caspase 12 pathways. At last, we provided evidence that p53 was identified as a protein target of lncRNA MEG3 to regulate NF-κB- and ERS-associated apoptosis. Taken collectively, our findings demonstrated that lncRNA MEG3 knockdown exerted cardioprotection by reducing ERS-mediated apoptosis through targeting p53 post-MI.

Down-regulated microRNA-183 mediates the Jak/Stat signaling pathway to attenuate hippocampal neuron injury in epilepsy rats by targeting Foxp1

Recently, the impacts of microRNAs (miRNAs) have been identified in epilepsy (EP), this study was designed to assess the role of miR-183 in hippocampal neuron injury in EP. Rat EP models were established by injected with lithium-pilocarpine. The pathological observation of rats' hippocampus sections was conducted. Expression of miR-183, Foxp1, Jak1, Stat1, and Stat3 in rats' hippocampal tissues was determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. The proliferation ability and the apoptosis of the rats' neurons were measured. Furthermore, the target relation between miR-183 and Foxp1 was determined by bioinformatics analysis and dual-luciferase gene reporter assay. The levels of miR-183, Jak1, Stat1, and Stat3 were elevated, and the expression of Foxp1 was declined in EP rats' hippocampal tissues. Inhibited miR-183 could up-regulate Foxp1, inhibited miR-183 together with up-regulated Foxp1 could repress hippocampal neuron injury, promote neuron proliferation, suppress neuron apoptosis, and inactivate the Jak/Stat signaling pathway, resulting in an attenuation of EP progression. Moreover, down-regulated Foxp1 could reverse the attenuation of EP progression which was contributed by inhibited miR-183. Our study implies that inhibited miR-183 could up-regulate Foxp1, resulting in an inactivation of the Jak/Stat signaling pathway and promotion of neuron proliferation, as well as inhibition of apoptosis of hippocampal neurons in EP rats, by which the hippocampal neuron injury and EP progression could be repressed.

Long noncoding RNA-MEG3 contributes to myocardial ischemia-reperfusion injury through suppression of miR-7-5p expression

Long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) plays an important role in protection of ischemia–reperfusion (I/R) injury in brain and liver. However, role of MEG3 in myocardial I/R injury remains unclear. Here, the role of MEG3 in protection of myocardial I/R injury and its association with microRNA-7-5p (miR-7-5p) was investigated using rat cardiac I/R model and myocardial I/R cell model. Our results showed that MEG3 was significantly up-regulated and miR-7-5p was significantly down-regulated after I/R. Following I/R, the levels of intact PARP and intact caspase-3 were reduced, while the cleaved fragments of PARP and caspase-3 were increased. TUNEL assay showed an increase in cardiomyocyte apoptosis after I/R. The levels of I/R-induced creatine kinase (CK) and lactate dehydrogenase (LDH) were inhibited by knockdown of MEG3 (siMEG3). SiMEG3 increased cell proliferation and inhibited cell apoptosis after I/R. In contrast, overexpression of MEG3 increased the I/R-induced CK and LDH activities and cell apoptosis and decreased cell proliferation. The dual-luciferase reporter system showed a direct binding of MEG3 to miR-7-5p. The level of miR-7-5p was negatively associated with the change in levels of MEG3 in H9c2 cells. The levels of intact RARP1 and caspase-3 were significantly increased by knockdown of MEG3. Co-transfection of miR-7-5p inhibitor with siMEG3 activates CK and LDH, significantly decreased cell proliferation, increased cell apoptosis, and decreased intact poly(ADP-ribose) polymerase 1 (PARP1) and caspase-3. In summary, down-regulation of MEG3 protects myocardial cells against I/R-induced apoptosis through miR-7-5p/PARP1 pathway, which might provide a new therapeutic target for treatment of myocardial I/R injury.

lncRNA ANRIL protects H9c2 cells against hypoxia-induced injury through targeting the miR-7-5p/SIRT1 axis

BACKGROUND

Acute myocardial infarction (AMI) occurred in the heart, which underwent long-term ischemia, and was mainly caused by hypoxia. Recently, studies have uncovered the participation of long noncoding RNAs (lncRNAs) in the pathogenesis of heart disease. Here, we planned to probe the role and molecular basis of ANRIL in hypoxia-induced H9c2 cell injury.

METHODS

Trypan blue exclusion assay and Transwell and flow cytometry assays were conducted to assess hypoxia-induced injury by determining the viability, migration, invasion, and apoptosis of H9c2 cells in different conditions, respectively. Gene expressions were evaluated by quantitative real-time polymerase chain reaction or western blot analysis as needed. RNA immunoprecipitation and luciferase reporter assays were applied to confirm the associations among genes.

RESULTS

ANRIL expression was dramatically enhanced in hypoxia-injured H9c2 cells, and silencing ANRIL aggravated hypoxia-induced H9c2 cell injury. ANRIL positively regulated sirtuin 1 (SIRT1) expression via competitively binding with miR-7-5p. Moreover, inhibition of miR-7-5p counteracted ANRIL depletion-exacerbated injury in hypoxic H9c2 cells, meanwhile, forced SIRT1 expression attenuated the injury-promoting effect of miR-7-5p upregulation on hypoxic H9c2 cells.

CONCLUSION

Our findings disclosed that ANRIL plays a protective part in hypoxia-induced H9c2 cell injury via modulating the miR-7-5p/SIRT1 axis, suggesting the great potential of ANRIL as a protective target for AMI.

Maternally expressed gene 3 in metabolic programming

Maternally Expressed Gene 3 (MEG3) is a long noncoding RNA (lncRNA) that coordinates a diverse array of cellular processes requiring epigenetic regulation of genes and interactions with key signaling proteins and by acting as a competitive endogenous (ce)RNA. Epigenetic modifications driven by in utero nutrition affect MEG3 expression and its role in the development of multiple metabolic disorders. This review examines how epigenetic modification of MEG3 expression can confer adaptedness to different metabolic environments. To this end, we discuss how nutritional status that leads to an increase of MEG3 expression can protect against cancer and metabolic dysfunctions, while interventions that promote MEG3 downregulation minimize the pleiotropic costs associated with its expression. Lastly, we identify research directions that would further shed light on the role of MEG3 in metabolic regulation and in functional imprinted gene networks. This article is part of a Special Issue entitled: ncRNA in control of gene expression edited by Kotb Abdelmohsen.

Long non-coding RNA MEG3 serves as a ceRNA for microRNA-145 to induce apoptosis of AC16 cardiomyocytes under high glucose condition

Diabetic cardiomyopathy (DCM) is one of the most serious complications of diabetes, but its pathogenesis remains largely unclear. In the present study, we aimed to explore the potential role of long non-coding RNA (lncRNA) maternally expressed gene 3 (MEG3) and to investigate the underlying mechanisms in human AC16 cardiomyocytes under high glucose (HG) condition. The results demonstrated that MEG3 was overexpressed in HG-treated AC16 cells, and MEG3 knockdown suppressed the HG-induced apoptosis in AC16 cells. Mechanistically, MEG3 directly binds to miR-145 in AC16 cells, thereby up-regulating the expression of PDCD4. Rescue experiments showed that the role of MEG3 in HG-treated AC16 cells was partly dependent on its suppression on miR-145. In summary, our findings suggested that the role of MEG3 in HG-treated human cardiomyocytes is to serve as a competing endogenous RNA (ceRNA), which negatively regulates miR-145. These findings may provide a valuable and promising therapeutic target for the treatment of DCM in the future.

A novel long noncoding RNA FAF inhibits apoptosis via upregulating FGF9 through PI3K/AKT signaling pathway in ischemia-hypoxia cardiomyocytes

Long noncoding RNAs (lncRNAs) have been increasingly considered to play an important role in the pathological process of various cardiovascular diseases, which often bind to the proximal promoters of the protein-coding gene to regulate the protein expression. However, the functions and mechanisms of lncRNAs in cardiomyocytes have not been fully elucidated. High-throughput RNA sequencing was performed to identify the differently expressed lncRNAs and messenger RNAs (mRNAs) between acute myocardial infarction (AMI) rats and healthy controls. One novel lncRNA FGF9-associated factor (termed FAF) and mRNAs in AMI rats were verified by bioinformatics, real-time polymerase chain reaction or western blot. Moreover, RNA fluorescence in situ hybridization was performed to determine the location of lncRNA. Subsequently, a series of in vitro assays were used to observe the functions of lncRNA FAF in cardiomyocytes. The expression of lncRNA FAF and FGF9 were remarkably decreased in ischemia-hypoxia cardiomyocytes and heart tissues of AMI rats. Overexpression of FAF could significantly inhibit cardiomyocytes apoptosis induced by ischemia and hypoxia. Conversely, knockdown of lncRNA FAF could promote apoptosis in ischemia-hypoxia cardiomyocytes. Moreover, overexpression of lncRNA FAF could also increase the expression of FGF9. Knockdown of the FGF9 expression could promote apoptosis in cardiomyocytes with the insult of ischemia and hypoxia, which was consistent with the effect of lncRNA FAF overexpression on cardiomyocyte apoptosis. Mechanistically, FGF9 inhibited cardiomyocytes apoptosis through activating signaling tyrosine kinase FGFR2 via phosphoinositide 3-kinase/protein kinase B signaling pathway. Thus, lncRNA FAF plays a protective role in ischemia-hypoxia cardiomyocytes and may serve as a treatment target for AMI.

Long noncoding RNA/circular noncoding RNA-miRNA-mRNA axes in cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of death worldwide. Non-coding RNAs including long non-coding RNAs (lncRNAs), circular RNAs (circRNAs) and microRNAs (miRNAs) have been reported to participate in pathological developments of CVDs through various mechanisms. Among them, the networks among lncRNAs/circRNAs, miRNAs, and mRNAs have recently attracted attention. Understanding the molecular mechanism could aid the discovery of therapeutic targets or strategies in CVDs including atherosclerosis, myocardial infarction (MI), hypertrophy, heart failure (HF) and cardiomyopathy. In this review, we summarize the latest research involving the lncRNA/circRNA-miRNA-mRNA axis in CVDs, with emphasis on the molecular mechanism.

STAT1-avtiviated LINC00961 regulates myocardial infarction by the PI3K/AKT/GSK3β signaling pathway

Myocardial infarction (MI) remains a severe cardiac disease because of its high incidence and mortality worldwide. A growing body of recent investigations have confirmed that LINC00961 acts as a tumor suppressor in diverse malignancies. However, the biological significance of LINC00961 and its molecular mechanism in MI are still elusive. Hypoxia is the leading cause of MI and induces myocardial injury. In this study, we found the upregulated expression of LINC00961 in cardiomyocytes H9c2 after hypoxia treatment. Knockdown of LINC00961 ameliorated hypoxia-induced cell injury by facilitating cell viability while repressing cell apoptosis. The significant increase of signal transducer and activator of transcription 1 (STAT1) expression and phosphorylation levels was observed in hypoxia-induced cells and proved to exacerbate hypoxia injury. In addition, STAT1 transcriptionally activated LINC00961 by binding to LINC00961 promoter. Furthermore, our results validated that suppressing LINC00961 contributed to the remarkable diminution in the phosphorylation levels of phosphoinositide 3-kinases (PI3K), AKT, and glycogen synthase kinase-3β (GSK3β). Inhibition of PI3K/AKT signaling or GSK3β pathway rescued the effects of LINC00961 knockdown on the hypoxia-induced injury of cardiomyocytes. Namely, we concluded that STAT1-avtiviated LINC00961 accelerated MI via the PI3K/AKT/GSK3β pathway, which may provide clues for the treatment of patients with MI.

Hypoxia-induced regulation of mTOR signaling by miR-7 targeting REDD1

Oxygen is an important factor mediating cell growth and survival under physiological and pathological conditions. Therefore, cells have well-regulated response mechanisms in the face of changes in oxygen levels in their environment. A subset of microRNAs (miRNAs) termed the hypoxamir has been suggested to be a critical mediator of the cellular response to hypoxia. Regulated in development and DNA damage response 1 (REDD1) is a negative regulator of mammalian target of rapamycin (mTOR) signaling in the response to cellular stress, and is elevated in many cell types under hypoxia, with consequent inhibition of mTOR signaling. However, the underlying posttranscriptional regulatory mechanism by miRNAs that contribute to this hypoxia-induced reduction in REDD1 expression remain unknown. Therefore, the aim of the current study was to identify the miRNAs participating in the hypoxic cellular response by scanning the 3'-untranslated region (3'-UTR) of REDD1 for potential miRNA-binding sites using a computer algorithm, TargetScan. miR-7 emerged as a novel hypoxamir that regulates REDD1 expression and is involved in mTOR signaling. miR-7 could repress REDD1 expression posttranscriptionally by directly binding with the 3'-UTR. Upon hypoxia, miR-7 expression was downregulated in HeLa cells to consequently derepress REDD1, resulting in inhibition of mTOR signaling. Moreover, overexpression of miR-7 was sufficient to reverse the hypoxia-induced inhibition of mTOR signaling. Therefore, our findings suggest miR-7 as a key regulator of hypoxia-mediated mTOR signaling through modulation of REDD1 expression. These findings contribute new insight into the miRNA-mediated molecular mechanism of the hypoxic response through mTOR signaling, highlighting potential targets for tumor suppression.

MiR-182 alleviates the development of cyanotic congenital heart disease by suppressing HES1

miRNAs have been pointed to play critical roles in the protection and development of cyanotic congenital heart disease (CHD). MiR-182 is found to be associated with multiple heart diseases. However, little is known about the function and underlying mechanisms of miR-182 on cyanotic CHD. Here, H9c2 cells were exposed to hypoxia to construct the model of cyanotic CHD in vitro. qRT-PCR assay revealed that miR-182 expression was downregulated in serum samples from patients with cyanotic CHD and hypoxia-induced cardiomyocytes. Gain- and loss-of-function demonstrated that miR-182 overexpression promoted cell proliferation and suppressed apoptosis in hypoxia-induced H9c2 cells, while miR-182 knockdown repressed cell proliferation and promoted apoptosis. Dual-luciferase reporter assay verified that HES1 was a direct target of miR-182, and miR-182 repressed HES1 expression by binding to its 3'-UTR. Moreover, miR-182-mediated regulatory effect on cell proliferation and apoptosis was reversed by the restoration of HES1 expression. In conclusion, our study demonstrated that miR-182 exerted protection effect through suppressing HES1 in hypoxia-induced cardiomyocytes, highlighting its role as a potential therapeutic strategy for cyanotic CHD.

A Hearty Dose of Noncoding RNAs: The Imprinted DLK1-DIO3 Locus in Cardiac Development and Disease

The imprinted Dlk1-Dio3 genomic region harbors a noncoding RNA cluster encoding over fifty microRNAs (miRNAs), three long noncoding RNAs (lncRNAs), and a small nucleolar RNA (snoRNA) gene array. These distinct noncoding RNAs (ncRNAs) are thought to arise from a single polycistronic transcript that is subsequently processed into individual ncRNAs, each with important roles in diverse cellular contexts. Considering these ncRNAs are derived from a polycistron, it is possible that some coordinately regulate discrete biological processes in the heart. Here, we provide a comprehensive summary of Dlk1-Dio3 miRNAs and lncRNAs, as they are currently understood in the cellular and organ-level context of the cardiovascular system. Highlighted are expression profiles, mechanistic contributions, and functional roles of these ncRNAs in heart development and disease. Notably, a number of these ncRNAs are implicated in processes often perturbed in heart disease, including proliferation, differentiation, cell death, and fibrosis. However, most literature falls short of characterizing precise mechanisms for many of these ncRNAs, warranting further investigation. Taken together, the Dlk1-Dio3 locus represents a largely unexplored noncoding regulator of cardiac homeostasis, harboring numerous ncRNAs that may serve as therapeutic targets for cardiovascular disease.

LncRNA-MALAT1 promotes CPC proliferation and migration in hypoxia by up-regulation of JMJD6 via sponging miR-125

The death of cardiomyocytes after myocardial infarction (MI) often leads to ventricular remodeling as well as heart failure (HF). The cardiac progenitor cells (CPCs) have the ability to regenerate functional heart muscle in patients after MI, which provides a promising method for MI-induced HF therapy. However, to date, CPCs can easily lose their proliferation ability in the infarcted myocardium. Therefore, exploring the mechanism for CPC proliferation is essential for CPC-based therapy in MI-induced HF. A previous study indicated that a hypoxic environment is essential for CPC proliferation, but the mechanism is not yet clear. In this work, we discovered that CoCl₂-induced hypoxia can promote CPC proliferation and migration. Additionally, long non-coding RNA MALAT1 expression was significantly up-regulated in the CoCl₂-induced hypoxia CPC model. MALAT1 suppression inhibited CPC proliferation and migration under hypoxic conditions. In addition, MALAT1 acted as a sponge for miR-125. The miR-125 inhibitor restored the proliferation and migration potentials of CPCs after a MALAT1 knockdown in hypoxia. A further study demonstrated that JMJD6 was a target of miR-125 whose expression was negatively regulated by miR-125. JMJD6 knockdown blocked miR-125 inhibitor's protective effect on CPC function in hypoxia. Ultimately, our finding demonstrated that MALAT1 can modulate CPC proliferation and migration potential through the miR-125/JMJD6 axis in hypoxia. Our finding provided a new regulatory mechanism for CPC proliferation in hypoxia, which provided a new target for MI-induced HF therapy.

Lost in translation: The 3'-UTR of IGF1R as an ancient long noncoding RNA

Background and objectives

The insulin-like growth factor (IGF) signaling system is a major arena of intragenomic conflict over embryonic growth between imprinted genes of maternal and paternal origin and the IGF type 1 receptor (IGF1R) promotes proliferation of many human cancers. The 3'-untranslated region (3'-UTR) of the mouse Igf1r mRNA is targeted by miR-675-3p derived from the imprinted H19 long noncoding RNA. We undertook a comparative sequence analysis of vertebrate IGF1R 3'-UTRs to determine the evolutionary history of miR-675 target sequences and to identify conserved features that are likely to be involved in post-transcriptional regulation of IGF1R translation.

Methodology

Sequences of IGF1R 3'-UTRs were obtained from public databases and analyzed using publicly available algorithms.

Results

A very long 3'-UTR is a conserved feature of vertebrate IGF1R mRNAs. We found that some ancient microRNAs, such as let-7 and mir-182, have predicted binding sites that are conserved between cartilaginous fish and mammals. One very conserved region is targeted by multiple, maternally expressed imprinted microRNAs that appear to have evolved more recently than the targeted sequences.

Conclusions and implications

The conserved structures we identify in the IGF1R 3'-UTR are strong candidates for regulating cell proliferation during development and carcinogenesis. These conserved structures are now targeted by multiple imprinted microRNAs. These observations emphasize the central importance of IGF signaling pathways in the mediation of intragenomic conflicts over embryonic growth and identify possible targets for therapeutic interventions in cancer.

Cardiac repair by epicardial EMT: Current targets and a potential role for the primary cilium

Despite therapeutic advances that have prolonged life, myocardial infarction (MI) remains a leading cause of death worldwide and imparts a significant economic burden. The advancement of treatments to improve cardiac repair post-MI requires the discovery of new targeted treatment strategies. Recent studies have highlighted the importance of the epicardial covering of the heart in both cardiac development and lower vertebrate cardiac regeneration. The epicardium serves as a source of cardiac cells including smooth muscle cells, endothelial cells and cardiac fibroblasts. Mammalian adult epicardial cells are typically quiescent. However, the fetal genetic program is reactivated post-MI, and epicardial epithelial-to-mesenchymal transition (EMT) occurs as an inherent mechanism to support neovascularization and cardiac healing. Unfortunately, endogenous EMT is not enough to encourage sufficient repair. Recent developments in our understanding of the mechanisms supporting the EMT process has led to a number of studies directed at augmenting epicardial EMT post-MI. With a focus on the role of the primary cilium, this review outlines the newly demonstrated mechanisms supporting EMT, the role of epicardial EMT in cardiac development, and promising advances in augmenting epicardial EMT as potential therapeutics to support cardiac repair post-MI.