lncRNA Myocardial Infarction-associated Transcript Research Articles

LncRNA MIAT suppresses inflammation in LPS-induced J774A.1 macrophages by promoting autophagy through miR-30a-5p/SOCS1 axi

Accumulated data implicate that long noncoding RNA (lncRNA) plays a pivotal role in rheumatoid arthritis (RA), potentially serving as a competitive endogenous RNA (ceRNA) for microRNAs (miRNAs). The lncRNA myocardial infarction-associated transcript (MIAT) has been demonstrated to regulate inflammation. However, the role of MIAT in the inflammation of RA remains inadequately explored. This study aims to elucidate MIAT’s role in the inflammation of lipopolysaccharide (LPS)-induced macrophages and to uncover the underlying molecular mechanisms. We observed heightened MIAT expression in LPS-induced J774A.1 cells and collagen-induced arthritis mouse models, in contrast to the expression pattern of miR-30a-5p. Silencing MIAT resulted in increased expression of the inflammatory cytokines IL-1β and TNF-α. Simultaneously, MIAT interference significantly impeded macrophage autophagy, evidenced by decreased expression of autophagy-related markers LC3-II and Beclin-1, alongside increased levels of p62 in LPS-induced J774A.1 cells. Notably, MIAT functioned as a ceRNA, sponging miR-30a-5p and exerting a negative regulatory influence on its expression. SOCS1 emerged as a target of miR-30a-5p, modulated by MIAT. Mechanistically, inhibiting miR-30a-5p reversed the impact of MIAT deficiency in promoting LPS-induced inflammation, while SOCS1 knockdown countered the cytokine inhibitory effect induced by silencing miR-30a-5p. In summary, this study indicates that lncRNA MIAT suppresses inflammation in LPS-induced J774A.1 macrophages by stimulating autophagy through the miR-30a-5p/SOCS1 axis. This suggests that MIAT holds promise as a potential therapeutic target for RA inflammation.

Diagnostic significance of LncRNA MIAT in periodontitis and the molecular mechanisms influencing periodontal ligament fibroblasts via the miR-204-5p/DKK1 axis

ObjectiveThis study investigated the clinical importance of long noncoding RNA myocardial infarction-associated transcript (MIAT) in periodontitis and its impact on the functional regulation of human periodontal ligament fibroblasts (hPDLFs). MethodsNinety-eight periodontitis patients and 74 healthy controls were enrolled. In vitro cellular models were created using Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) to stimulate hPDLFs. Real-time quantitative polymerase chain reaction was used to measure mRNA levels of MIAT and osteogenic factors. Inflammation factor concentration was assessed using an enzyme-linked immunosorbent assay. Cell viability and apoptosis were examined by cell counting kit −8 and flow cytometry assay. The targeting relationship was verified by the dual-luciferase reporter and RNA Immunoprecipitation assay. ResultsHighly expressed MIAT and Dicckopf-1 (DDK1), and lowly expressed miR-204–5p were found in the gingival crevicular fluid of periodontitis patients and Pg-LPS induced hPDLFs. MIAT has a sensitivity of 76.53 % and a specificity of 86.49 % for identifying patients with periodontitis among healthy individuals. MIAT acts as a sponge for miR-204–5p and upregulates DDK1 mRNA expression. Silencing of MIAT diminished the promotion of apoptosis and inflammation in hPDLFs by Pg-LPS and enhanced osteogenic differentiation. However, a miR-204–5p inhibitor significantly reversed the effect of silenced MIAT. ConclusionsMIAT may act as a promising biomarker for periodontitis. It modulates apoptosis, inflammation, and osteogenic differentiation of PDLFs by focusing on the miR-204–5p/DKK1 axis, indicating its potential as a new therapeutic target for treating periodontitis.

LncRNA Myocardial Infarction-Associated Transcript (MIAT)/miR-505-5p Axis Regulates Proliferation and Migration of Vascular Smooth Muscle Cells of Hypertension Mice

To clarify the role of long non-coding RNA (lncRNA) MIAT in regulating proliferative and migratory abilities in VSMCs extracted from hypertension mice via downregulating microRNA-505-5p (miR-505-5p). Serum levels of MIAT and miR-505-5p in enrolled 20 hypertension patients and 20 healthy volunteers were detected. VSMCs were extracted from hypertension mice and healthy mice. Regulatory effects of MIAT and miR-505-5p on proliferative and migratory abilities in VSMCs were examined. At last, the interaction between MIAT and miR-505-5p was explored by dual-luciferase reporter assay and rescue experiments. Serum level of MIAT was higher in hypertension patients than those of healthy subjects, while miR-505-5p was downregulated. MIAT level was negatively correlated to miR-505-5p level in serum of hypertension patients. Knockdown of MIAT suppressed proliferative and migratory abilities in VSMCs extracted from hypertension mice. In addition, knockdown of MIAT upregulated E-cadherin and downregulated Vimentin and Snail-1. MiR-505-5p was verified to be the target binding MIAT. Knockdown of miR-505-5p reversed regulatory effects of MIAT on VSMCs phenotypes. LncRNA MIAT stimulates VSMCs in hypertension mice to proliferate and migrate through downregulating miR-505-5p, which may be a promising target for diagnosis and treatment of hypertension.

Association between Genetic Polymorphism of The lncRNA MIAT rs1894720 with Ischemic Stroke Risk and lncRNA MIAT Expression Levels in The Blood after An Ischemic Stroke: A Case-Control Study.

Genetic aspects can play an essential role in the occurrence and development of ischemic stroke (IS). Rs1894720 polymorphism is one of the eight single nucleotide polymorphisms (SNPs) in the long non-coding RNA (lncRNA) myocardial infarction-associated transcript (MIAT) locus. The aim of study is the lncRNA MIAT rs1894720 polymorphism decreases IS risk by reducing lncRNA MIAT expression. In this case-control study, we studied 232 Iranian patients and 232 controls. The blood samples were collected from patients admitted at different times after stroke symptoms. We enrolled 80, 78, and 74 patients who arrived at the hospital between 0-24, 24-48, and 48-72 hours after the first appearance of symptoms, respectively. DNA genotyping was done by the tetra-primer ARMS-PCR method. Circulating MIAT levels were evaluated by real-time polymerase chain reaction (PCR). The GT genotype of MIAT rs1894720 showed a significant association with the risk of IS (OR=3.53, 95% CI=2.13-5.84, P<0.001). MIAT expression was higher relative to the control within the first hours after IS. The MIAT levels in IS patients with rs1894720 (GT) were significantly lower relative to patients who had the GG and TT genotypes. Linear regression model indicated a significant correlation between MIAT expression with atherosclerotic risk factors and types of stroke in IS patients. Receiver operating characteristic (ROC) curve analysis showed that the level of lncRNA MIAT after IS could be diagnostic with an area under the curve (AUC) of 0.82. The sensitivity and specificity were 80.17 and 67.24%, respectively (P<0.001). Our study demonstrated that the MIAT rs1894720 polymorphism (GT) might increase the risk of IS in the Iranian population. MIAT expression was up-regulated in our IS patients. Hence, it could be a diagnostic biomarker for IS.

MIAT shuttled by tumor-secreted exosomes promotes paclitaxel resistance in esophageal cancer cells by activating the TAF1/SREBF1 axis.

Chemoresistance remains a major obstacle to the treatment of esophageal cancer (EC). Exosome-mediated transfer of long noncoding RNAs (lncRNAs) has recently been unveiled to correlate with the regulation of drug resistance in EC. This study aimed to investigate the physiological mechanisms by which exosome-encapsulated lncRNA myocardial infarction-associated transcript (MIAT) derived from tumor cells might mediate the paclitaxel (PTX) resistance of EC cells. First, MIAT was experimentally determined to be upregulated in PTX nonresponders and PTX-resistant EC cells. Silencing of MIAT in PTX-resistant EC cells decreased cell viability and enhanced apoptosis, corresponding to a reduced half-maximal inhibitory concentration (IC50 ) value. Next, exosomes were isolated from EC109 and EC109/T cells, and EC109 cells were cocultured with EC109/T-cell-derived exosomes. Accordingly, MIAT was revealed to be transmitted through exosomes from EC109/T cells to EC109 cells. Tumor-derived exosomes carrying MIAT increased the IC50 value of PTX and suppressed apoptosis in EC109 cells to promote PTX resistance. Furthermore, MIAT promoted the enrichment of TATA-box binding protein-associated Factor 1 (TAF1) in the promoter region of sterol regulatory element binding transcription factor 1 (SREBF1), as shown by a chromatin immunoprecipitation assay. This might be the mechanism by which MIAT could promote PTX resistance. Finally, in vivo experiments further confirmed that the knockdown of MIAT attenuated the resistance of EC cells to PTX. Collectively, these results indicate that tumor-derived exosome-loaded MIAT activates the TAF1/SREBF1 axis to induce PTX resistance in EC cells, providing a potential therapeutic target for overcoming PTX resistance in EC.

LncRNA MIAT Modulates LPS-Induced Acute Kidney Injury via BECN1-Dependent Autophagy by Interacting with PTBP1.

Autophagy plays critical adaptive and nonadaptive roles in the pathogenesis of Sepsis-associated acute kidney injury (Sepsis-AKI). However, it remains unknown whether myocardial infarction associated transcript (MIAT) is involved in the process of autophagy in Sepsis-AKI. This study aimed to explore the exact association between MIAT1 and Beclin 1 (BECN1)-mediated autophagy in Sepsis-AKI in vitro. HK-2 (human renal tubular epithelial cell line) cells were stimulated by lipopolysaccharide (LPS) to construct a septic kidney injury cell model in vitro. The relative expression changes of genes or proteins in clinical samples and cells were examined by quantitative real-time polymerase chain reaction (qRT-PCR) or Western blot. Cell survival was detected by cell counting kit-8 (CCK-8) and flow cytometry analysis. The production of inflammatory mediators was determined using Enzyme-linked immunosorbent assay (ELISA) and qRT-PCR assays. The interlinked relationship between polypyrimidine tract-binding protein 1 (PTBP1) and MIAT or BECN1 was validated by RNA immunoprecipitation (RIP) and RNA pull-down detections. The expression of MIAT was up-regulated in Sepsis-AKI patients and LPS-stimulated HK-2 cells. Down-regulation of MIAT strikingly lightened LPS-induced cell apoptosis and inflammation, but enhanced cell viability. Evidenced by mechanistic experiments, MIAT silencing was confirmed to activate BECN1-mediated cell autophagy by interacting with PTBP1. Furthermore, the elimination of BECN1 remarkably reversed the antiapoptotic and anti-inflammatory roles mediated by MIAT silencing. In summary, the experimental data reinforced that MIAT downregulation attenuated LPS-stimulated renal cell inflammatory injury by promoting BECN1-mediated autophagy activation through binding to PTBP1, providing some new insights into the function and mechanism of MIAT in Sepsis-associated acute kidney injury (Sepsis-AKI).

LncRNA MIAT Upregulates NEGR1 by Competing for miR-150-5p as a Competitive Endogenous RNA in SCIRI Rats.

Spinal cord ischemia-reperfusion injury (SCIRI) can cause a pathological state of irreversible delayed death of neurons in the spinal cord tissue and a range of complications, such as spinal cord dysfunction and motor function impairment. This study aimed to determine whether the long-stranded non-coding ribonucleic acid (lncRNA), myocardial infarction-associated transcript (MIAT), could upregulate neuronal growth regulator 1 (NEGR1) by competing for miR-150-5p as a competitive endogenous RNA in a rat SCIRI model. The MIAT knockdown vector or the corresponding blank vector was injected into the spinal cord of healthy sprague Dawley (SD) rats. Administration of the MIAT knockdown vector led to the establishment of the SCIRI rat model. Basso, Beattie & Bresnahan locomotor rating scale (BBB) assessment of hind limb motion. Pathological changes in the spinal cord were observed via hematoxylin and eosin staining and eosin staining. Quantitative polymerase chain reaction was performed to determine the expression levels of the candidate microRNAs and predicted candidate genes, and the relationship between them. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay (TUNEL) staining was used to detect apoptosis in the spinal cord tissue of rats in each group. Western blotting was performed to determine the expression of the apoptosis-related proteins, caspase-9, caspase-3, and BCL2-Associated X (Bax)/B-cell lymphoma-2 (Bcl-2). The luciferase reporter gene was used to assess the interaction among the lncRNA, MIAT, and miR-150-5, and the interaction between miR-150-5 and NEGR1. The sh-lncRNA, MIAT, improved exercise status, and pathological changes in the spinal cord of SCIRI rats, inhibited apoptosis, increased the expression of miR-150-5p, and reduced the expression of NEGR1. Compared with mimics-NC, the transfection of miR-150-5p significantly decreased the relative fluorescence activity ratio of MIAT 3'-untranslated region (3'-UTR) wild-type Human embryonic kidney cells 293 (HEK-293 cells). Compared with mimics-negative control (NC), the transfection of miR-150-5p significantly decreased the relative fluorescence activity ratio of NEGR1 3'-UTR wild-type HEK-293 cells. MIAT can affect the symptoms of SCIRI in rats. Furthermore, as a competitive endogenous RNA, MIAT upregulates NEGR1 by competing with miR-150-5p in SCIRI rats.

The LncRNA MIAT is identified as a regulator of stemness-associated transcript in glioma.

Myocardial infarction-associated transcript (MIAT) is a long non-coding RNA (lncRNA) with altered expression in different diseases and malignancies. In this study, the potential expression and function of lncRNA MIAT in intuition and progression of brain cancer was investigated. At first, TCGA data analysis demonstrated that lncRNA MIAT is significantly upregulated in various malignancies, especially its expression is dramatically elevated in brain tumors. In line with the data, we further evaluated the expression of MIAT in a series of brain tumor tissue, and our results revealed that the expression of MIAT was noticeably overexpressed in glioblastoma (p = < 0.0001). We further found that the expression of MIAT was markedly upregulated in low-grade brain tumors rather than high-grade ones. To further investigate the biological function of MIAT in brain cancer cells, its expression was suppressed by si-RNA-mediated knocking down. Inhibition of MIAT resulted in reduced proliferation of brain tumor cells followed by cell cycle arrest at the G1 phase, and significant induction of apoptosis, and senescence, but limited the migration ability and epithelial-mesenchymal-transition (EMT). Moreover, knocking-down of MIAT reduced the expression of stemness factors, followed by upregulation of their downstream miRNAs (micro RNAs), let-7a-5p, and miR-29b-3p. Altogether, our data demonstrated that lncRNA MIAT could control proliferation, migration, and metastasis of brain cancer cells via regulating the Nanog/ Sox2 / let-7a-5p / miR-29b-3p axis. This data could introduce lncRNA MIAT as a novel oncogene in brain cancer pathogenesis.

Knockdown of long noncoding RNA MIAT attenuates hypoxia-induced cardiomyocyte injury by regulating the miR-488-3p/Wnt/β-catenin pathway.

Dysfunction of cardiomyocytes contributes to the development of acute myocardial infarction (AMI). Nonetheless, the regulatory mechanism of lncRNA myocardial infarction-associated transcript (MIAT) in cardiomyocyte injury remains largely unclear. The cardiomyocyte injury was assessed via cell viability and apoptosis using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) and flow cytometry, respectively. The levels of MIAT, microRNA (miR)-488-3p, and Wnt5a were detected via quantitative real-time polymerase chain reaction and Western blot. After bioinformatical analysis, the binding between miR-488-3p and MIAT or Wnt5a was confirmed via dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assays. Our results showed that MIAT expression was increased in AC16 cells after hypoxia treatment. Silencing of MIAT alleviated hypoxia-induced viability reduction, apoptosis increase, and Wnt/β-catenin pathway activation. MIAT directly targeted miR-488-3p. MiR-488-3p might repress hypoxia-induced cardiomyocyte injury, and its knockdown reversed the effect of MIAT depletion on cardiomyocyte injury. Wnt5a was validated as a target of miR-488-3p. Wnt5a expression restoration attenuated the influence of MIAT knockdown on hypoxia-triggered cardiomyocyte injury. Our findings demonstrated that downregulation of MIAT might mitigate hypoxia-induced cardiomyocyte injury partly through miR-488-3p mediated Wnt/β-catenin pathway.

Role of lncRNA MIAT/miR-361-3p/CCAR2 in prostate cancer cells.

The study was aimed to investigate the role and mechanism of long non-coding RNAs (lncRNA) myocardial infarction-associated transcript (MIAT) in prostate cancer. The relationships between lncRNA MIAT and miR-361-3p, miR-361-3p and cell cycle and apoptosis regulator 2 (CCAR2) were predicted by StarBase and TargetScan, and verified by dual-luciferase reporter assay and RNA pull-down assay. Quantitative real-time PCR assay was performed to detect the mRNA expression of lncRNA MIAT, miR-361-3p, CCAR2, Bax, and Bcl-2 in the prostate cancer tissues or cells. The protein levels of CCAR2, Bax, and Bcl-2 were detected by Western blot analysis. The cell viability and apoptosis were detected by MTT assay and Flow cytometry analysis, respectively. lncRNA MIAT was upregulated, while miR-361 was downregulated in the prostate cancer tissues and Du145 cells. lncRNA MIAT negatively regulated miR-361-3p expression in Du145 cells. Downregulating lncRNA MIAT decreased the cell viability, induced the cell apoptosis, increased Bax expression, and decreased Bcl-2 expression in Du145 cells, while the effects were reversed by downregulating miR-361-3p or CCAR2 upregulation. Moreover, CCAR2 upregulation reversed the effects of miR-361-3p upregulation on Du145 cell viability and apoptosis. In conclusion, lncRNA MIAT participated in prostate cancer by regulating cell proliferation and apoptosis via miR-361-3p/CCAR2 axis.

Clinicopathologic and prognostic significance of long non-coding RNA myocardial infarction-associated transcript in multiple cancers.

The aim of the meta-analysis was to explore the clinicopathological and prognostic significance of long non-coding RNA (lncRNA) myocardial infarction-associated transcript (MIAT) in various cancers. We searched multiple databases, including PubMed, China National Knowledge 53 Infrastructure (CNKI), Springer, Web of Science, and Cochrane, for articles on the prognostic value of lncRNA MIAT in various cancers before 25 March 2021. The odds ratio (OR) and 95% confidence interval (CI) were adopted to evaluate the clinicopathological features and outcomes of cancers. The Cancer Genome Atlas dataset was used to identify the differential expression and prognostic significance of lncRNA MIAT. We enrolled 14 publications, including 1,573 cancer patients. Higher lncRNA MIAT expression was significantly related to worse overall survival (OR=3.13, 95% CI: 2.47-3.96, p<0.05), regardless of cancer types, sample size, and follow-up time of the included studies. Additionally, higher lncRNA MIAT expression was associated with larger tumour sizes (OR=1.67, 95% CI: 1.24-2.26, p<0.05), advanced clinical stage (OR=4.79, 95% CI: 3.38-6.79, p<0.05), lymph nodes metastasis (OR=7.33, 95% CI: 4.61-11.67, p<0.05), and distant metastasis (OR=2.62, 95% CI: 1.88-3.66, p<0.05), but not associated with age and gender. We found no publication bias, and sensitivity analysis indicated that the results were reliable. Higher lncRNA MIAT expression may predict larger tumour sizes, advanced clinical stage, metastasis of cancers, and lower overall survival rate. LncRNA MIAT may serve as a useful clinicopathological and prognostic biomarker for cancers.

Long Noncoding RNA MIAT Regulates Hyperosmotic Stress-Induced Corneal Epithelial Cell Injury via Inhibiting the Caspase-1-Dependent Pyroptosis and Apoptosis in Dry Eye Disease.

PurposeThe biological role and mechanism of long noncoding RNA (lncRNA) myocardial infarction-associated transcript (MIAT) in dry eye remain to be illustrated. Pyroptosis is a noticeable form of inflammatory activation, which is characteristic of gasdermin D (GSDMD)-driven cell death. The present study was designed to explore the role of MIAT in pyroptosis and apoptosis induced by hyperosmolarity stress (HS) in human corneal epithelial cells (HCECs).MethodsHCECs were cultured in 70–120 mM hyperosmotic medium for 24 h to create a dry eye model in vitro. The level of the pyroptosis marker GSDMD was measured, and the cell inflammatory response was evaluated by detecting IL-1β and IL-18 levels. Exogenous caspase-1 inhibitor Ac-YVAD-CHO was used. The pyroptosis in HCECs was examined by caspase-1 activity, immunofluorescent staining, and Western blotting. Flow cytometry was performed to test the apoptosis rate of HCECs. Cell migration and proliferation were detected. The expression of the lncRNA MIAT in HCECs was detected by quantitative real-time PCR. MIAT was knocked down by small interfering RNA (siRNA) transfection. The effects of caspase-1 inhibition on pyroptosis, apoptosis, migration, and proliferation were observed.ResultsHS promoted pyroptosis in HCECs by elevating caspase-1, GSDMD, and the active cleavage of GSDMD (N-terminal domain, N-GSDMD), and increased the release of IL-1β, IL-18, LDH and the rate of apoptosis, with reduced cell migration. These changes were prevented by the inhibition of caspase-1. The expression of MIAT was significantly increased in HCECs exposed to a hyperosmotic medium. Silencing MIAT increased the expression of GSDMD, caspase-1, and inflammatory chemokines IL-1β and IL-18, and promoted apoptosis while inhibiting migration and proliferation in HCECs.ConclusionThe lncRNA MIAT is involved in HS-induced pyroptosis and apoptosis and the inflammatory response of HCECs and provides a new understanding of the pathogenesis of dry eye.

LncRNA MIAT Promotes Spinal Cord Injury Recovery in Rats by Regulating RBFOX2-Mediated Alternative Splicing of MCL-1.

LncRNA myocardial infarction-associated transcript (MIAT) alleviates acute spinal cord injury (ASCI)-induced neuronal cell apoptosis, but the specific mechanism of it involved in regulating SCI progression needs further exploration. Here, a SCI rat model was established, followed by administration with adenovirus-mediated MIAT overexpression vector (Ad-MIAT) alone or together with Ad-RBFOX2 (RNA binding fox-1 homolog 2). The data indicated that MIAT overexpression promoted motor function recovery, improved morphology of injured tissues, and restrained neuron loss and cell apoptosis in SCI rats. Then, PC-12 cells were treated with H2O2 to induce cell injury. And highly expressed MIAT suppressed H2O2-caused decrease in cell viability and increase in cell apoptosis. MIAT stabilized RBFOX2 protein expression by binding to RBFOX2, thereby promoting RBFOX2-induced upregulation of anti-apoptotic MCL-1L (myeloid cell leukemia sequence 1) and reduction of pro-apoptotic MCL-1S. And silencing RBFOX2 in vitro blocked the inhibitory effect of MIAT on cell apoptosis. Moreover, MCL-1-specific steric-blocking oligonucleotides (SBOs) were used to transfer the MCL-1 pre-mRNA splicing pattern from MCL-1L to MCL-1S. SBOs reversed the protection effect of RBFOX2 overexpression on H2O2-induced cell injury. Furthermore, overexpression of MCL-1L instead of MCL-1S facilitated autophagy activation in H2O2-stimulated cells. Interestingly, co-overexpression of MIAT and RBFOX2 had a better promoting effect on SCI recovery. In conclusion, MIAT mitigated SCI by promoting RBFOX2-mediated alternative splicing of MCL-1. Our findings might provide a promising therapeutic target for SCI.

Silencing of Long Noncoding RNA MIAT Contributes to Relieving Sepsis-Induced Myocardial Depression via the NF-κB Axis

IntroductionSepsis represents a life-threatening disease caused by a series of infections, which may be complicated with severe myocardial depression (MD). Long noncoding RNAs (lncRNAs) are closely related to sepsis-induced myocardial depression (SIMD). This study aimed to seek out the mechanism of lncRNA myocardial infarction-associated transcript (MIAT) in the growth of SIMD. MethodsVenous blood samples were collected from 62 patients with sepsis; the sepsis rat model was established with 15 mg/kg lipopolysaccharide (LPS), and the H9C2 cardiomyocyte injury model was established with 1 μg/mL LPS. In the rat and cardiomyocyte models, MIAT was inhibited. The expression of MIAT in normal tissues and SIMD tissues was detected. Then, the functional assays of MIAT were performed in rats and H9C2 cells for detection of cardiac function, hemodynamics, inflammation response, myocardial function, oxidative stress, tissue stainings, and cardiomyocyte viability and apoptosis. Western blot analysis was used to measure the levels of apoptosis-related proteins and the nuclear factor kappa B (NF-κB) axis-related proteins. ResultsMIAT was highly expressed in SIMD patients. Silencing MIAT alleviated inflammation and apoptosis and improved myocardial function in SIMD rats by downregulating the NF-κB axis. In LPS-induced H9C2 cardiomyocytes, silencing MIAT alleviated inflammation and oxidative stress and inhibited apoptosis by downregulating the NF-κB axis, thus mitigating cardiomyocyte injury. ConclusionsMIAT could assist the diagnosis of SIMD and might affect the progression of SIMD by regulating the NF-κB pathway.

LncRNA MIAT can regulate the proliferation, apoptosis, and osteogenic differentiation of bone marrow-derived mesenchymal stem cells by targeting miR-150-5p

ABSTRACT Osteoporosis (OP) is a systemic bone metabolic disease with complicated pathogenesis and is difficult to cure clinically. The regulatory mechanisms of OP are needed to be further investigated. In the present study, we focused on the role of myocardial infarction-associated transcript (MIAT) in OP development and examined the underlying mechanism. The serum expression levels of MIAT in samples from patients with OP and healthy controls were compared using quantitative reverse transcription-PCR (qRT-PCR). The dual-luciferase reporter assay was used to confirm the relationship between MIAT and its potential target microRNA, i.e., miR-150-5p. Moreover, bone marrow-derived mesenchymal stem cells (BMSCs) were cultured and transfected with MIAT shRNA, with or without miR-150-5p inhibitor. EdU staining and colony formation analysis were performed to determine the proliferation ability of these cells. Furthermore, the TUNEL assay and flow cytometry were used to assess BMSC apoptosis. Finally, RT-PCR and Western blot assays were employed to assess the expression of osteogenic differentiation biomarkers. Compared with controls, the expression of MIAT was significantly increased, whereas that of miR-150-5p was markedly decreased in patients with OP. MIAT and miR-150-5p expression levels exhibited a strong negative correlation. Furthermore, osteogenic differentiation indicators were suppressed in serum of OP patients. MIAT was downregulated, and miR-150-5p was upregulated in induced to osteogenic differentiation BMSCs. Furthermore, downregulation of MIAT dramatically promoted osteogenic differentiation, increased proliferation, and inhibited apoptosis in BMSCs; miR-150-5p inhibitor abrogated the effects of MIAT. In conclusion, lncRNA MIAT can regulate the proliferation, apoptosis, and osteogenic differentiation of BMSCs.

Curcumin improves atherosclerosis by inhibiting the epigenetic repression of lncRNA MIAT to miR-124.

Objectives: Atherosclerosis is a dominant cardiovascular disease. Curcumin has protective effect on atherosclerosis. However, the mechanisms remain to be explored. Methods: Atherosclerosis was induced by feeding mice with high-fat diet (HFD) and ox-low-density lipoprotein (LDL)-induced human umbilical vein endothelial cells (HUVECs) were structured. Oil Red O staining was used to evaluate the plaques in the artery. Quantitative real-time PCR (qRT-PCR) was conducted to detect the level of myocardial infarction associated transcript (MIAT), miR-124, and enhancer of zeste homolog 2 (EZH2). We performed western blotting and enzyme linked immunosorbent assay to examine the expression of EZH2 and cytokines including IL-1β, TNFα, IL-6, and IL-8, respectively. RNA immunoprecipitation and chromatin immunoprecipitation (ChIP) were used to validate the interaction between myocardial infarction associated transcript and EZH2. Flow cytometry and CCK-8 assay were used to examine cell apoptosis and proliferation, respectively. Results: Curcumin suppressed inflammation in atherosclerosis mouse model and ox-LDL-induced cell model. MIAT overexpression and miR-124 inhibition relieved the anti-inflammation effect of curcumin in ox-LDL-induced cell. MIAT regulated miR-124 by interacting with EZH2. Curcumin relieved ox-LDL-induced cell inflammation via regulating MIAT/miR-124 pathway. Conclusion: MIAT/miR-124 axis mediated the effect of curcumin on atherosclerosis and altered cell apoptosis and proliferation, both in vivo and in vitro. These data further support the application of curcumin in control of atherosclerosis advancement.

LncRNA MIAT enhances cerebral ischaemia/reperfusion injury in rat model via interacting with EGLN2 and reduces its ubiquitin-mediated degradation.

Long non‐coding RNA (lncRNA) MIAT (myocardial infarction associated transcript) has been characterized as a functional lncRNA modulating cerebral ischaemic/reperfusion (I/R) injury. However, the underlying mechanisms remain poorly understood. This study explored the functional partners of MIAT in primary rat neurons and their regulation on I/R injury. Sprague‐Dawley rats were used to construct middle cerebral artery occlusion (MCAO) models. Their cerebral cortical neurons were used for in vitro oxygen‐glucose deprivation/reoxygenation (OGD/R) models. Results showed that MIAT interacted with EGLN2 in rat cortical neurons. MIAT overexpression or knockdown did not alter EGLN2 transcription. In contrast, MIAT overexpression increased EGLN2 stability after I/R injury via reducing its ubiquitin‐mediated degradation. EGLN2 was a substrate of MDM2, a ubiquitin E3 ligase. MDM2 interacted with the N‐terminal of EGLN2 and mediated its K48‐linked poly‐ubiquitination, thereby facilitating its proteasomal degradation. MIAT knockdown enhanced the interaction and reduced EGLN2 stability. MIAT overexpression enhanced infarct volume and induced a higher ratio of neuronal apoptosis. EGLN2 knockdown significantly reversed the injury. MIAT overexpression reduced oxidative pentose phosphate pathway flux and increased oxidized/reduced glutathione ratio, the effects of which were abrogated by EGLN2 knockdown. In conclusion, MIAT might act as a stabilizer of EGLN2 via reducing MDM2 mediated K48 poly‐ubiquitination. MIAT‐EGLN2 axis exacerbates I/R injury via altering redox homeostasis in neurons.

Long Noncoding RNA MIAT Controls Advanced Atherosclerotic Lesion Formation and Plaque Destabilization.

Long noncoding RNAs (lncRNAs) are important regulators of biological processes involved in vascular tissue homeostasis and disease development. The present study assessed the functional contribution of the lncRNA myocardial infarction-associated transcript (MIAT) to atherosclerosis and carotid artery disease. We profiled differences in RNA transcript expression in patients with advanced carotid artery atherosclerotic lesions from the Biobank of Karolinska Endarterectomies. The lncRNA MIAT was identified as the most upregulated noncoding RNA transcript in carotid plaques compared with nonatherosclerotic control arteries, which was confirmed by quantitative real-time polymerase chain reaction and in situ hybridization. Experimental knockdown of MIAT, using site-specific antisense oligonucleotides (LNA-GapmeRs) not only markedly decreased proliferation and migration rates of cultured human carotid artery smooth muscle cells (SMCs) but also increased their apoptosis. MIAT mechanistically regulated SMC proliferation through the EGR1 (Early Growth Response 1)-ELK1 (ETS Transcription Factor ELK1)-ERK (Extracellular Signal-Regulated Kinase) pathway. MIAT is further involved in SMC phenotypic transition to proinflammatory macrophage-like cells through binding to the promoter region of KLF4 and enhancing its transcription. Studies using Miat-/- and Miat-/-ApoE-/- mice, and Yucatan LDLR-/- mini-pigs, as well, confirmed the regulatory role of this lncRNA in SMC de- and transdifferentiation and advanced atherosclerotic lesion formation. The lncRNA MIAT is a novel regulator of cellular processes in advanced atherosclerosis that controls proliferation, apoptosis, and phenotypic transition of SMCs, and the proinflammatory properties of macrophages, as well.

Downregulation of MIAT reduces the proliferation and migratory and invasive abilities of retinoblastoma cells by sponging miR-665 and regulating LASP1.

Long non-coding RNAs (lncRNAs) can function as onco-lncRNAs in several types of human cancer, including retinoblastoma (Rb). The present study investigated the potential role and regulatory mechanism of the lncRNA myocardial infarction-associated transcript (MIAT) in Rb. To do so, the expression levels of MIAT, microRNA (miR)-665, and LIM and SH3 protein 1 (LASP1) in Rb tissues from patients or Rb cells were analysed using reverse transcription quantitative PCR. The interactions between miR-665 and MIAT/LASP1 were confirmed by the dual-luciferase reporter assay. MTT, Transwell (to assess migration and invasion) and western blotting assays were used to explore the functions of the MIAT/miR-665/LASP1 axis on Rb progression in vitro. The results of the present study indicated that MIAT targeted miR-665. In Rb tissues and cell lines, high expression of MIAT was observed, whereas miR-665 was downregulated in Rb tissues. Furthermore, the proliferation and migratory and invasive abilities of Rb Y79 and HXO-RB44 cells were decreased following MIAT downregulation or miR-665 overexpression. In addition, LASP1 was identified as a target gene of miR-665. Both the decreased expression of miR-665 and the elevated expression of LASP1 reversed the suppressive effects of MIAT knockdown on the proliferation and migratory and invasive abilities of Y79 cells. Furthermore, MIAT silencing attenuated the development of Rb by regulating the miR-665/LASP1 axis. Taken together, these findings suggested that MIAT may be considered as a possible therapeutic target for Rb.

Long Noncoding RNA MIAT Modulates the Extracellular Matrix Deposition in Leiomyomas by Sponging MiR-29 Family.

The objective of this study was to determine the expression and functional role of a long noncoding RNA (lncRNA) MIAT (myocardial infarction-associated transcript) in leiomyoma pathogenesis. Leiomyoma compared with myometrium (n = 66) expressed significantly more MIAT that was independent of race/ethnicity and menstrual cycle phase but dependent on MED12 (mediator complex subunit 12) mutation status. Leiomyomas bearing the MED12 mutation expressed higher levels of MIAT and lower levels of microRNA 29 family (miR-29a, -b, and -c) compared with MED12 wild-type leiomyomas. Using luciferase reporter activity and RNA immunoprecipitation analysis, MIAT was shown to sponge the miR-29 family. In a 3-dimensional spheroid culture system, transient transfection of MIAT siRNA in leiomyoma smooth muscle cell (LSMC) spheroids resulted in upregulation of miR-29 family and downregulation of miR-29 targets, collagen type I (COL1A1), collagen type III (COL3A1), and TGF-β3 (transforming growth factor β-3). Treatment of LSMC spheroids with TGF-β3 induced COL1A1, COL3A1, and MIAT levels, but repressed miR-29 family expression. Knockdown of MIAT in LSMC spheroids blocked the effects of TGF-β3 on the induction of COL1A1 and COL3A1 expression. Collectively, these results underscore the physiological significance of MIAT in extracellular matrix accumulation in leiomyoma.