Silencing lncRNA TUG1 Alleviates LPS-Induced Mouse Hepatocyte Inflammation by Targeting miR-140/TNF

LncRNA TUG1 mediates microglial inflammatory activation by regulating glucose metabolic reprogramming

Microglia are natural immune cells in the central nervous system, and the activation of microglia is accompanied by a reprogramming of glucose metabolism. In our study, we investigated the role of long non-coding RNA taurine-upregulated gene 1 (TUG1) in regulating microglial glucose metabolism reprogramming and activation. BV2 cells were treated with Lipopolysaccharides (LPS)/Interferon-γ (IFN-γ) to establish a microglial activation model. The glycolysis inhibitor 2-Deoxy-D-glucose (2-DG) was used as a control. The expression levels of TUG1 mRNA and proinflammatory cytokines such as Interleukin-1β (IL-1β), Interleukin -6, and Tumor Necrosis Factor-α mRNA and anti-inflammatory cytokines such as IL-4, Arginase 1(Arg1), CD206, and Ym1 were detected by RT-qPCR. TUG1 was silenced using TUG1 siRNA and knocked out using CRISPR/Cas9. The mRNA and protein expression levels of key enzymes involved in glucose metabolism, such as Hexokinase2, Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Lactate dehydrogenase, Glucose 6 phosphate dehydrogenase, and Pyruvate dehydrogenase (PDH), were determined by RT-qPCR and Western blotting. The glycolytic rate of microglial cells was measured using Seahorse. Differential metabolites were determined by metabolomics, and pathway enrichment was performed using these differential metabolites. Our findings revealed that the expression of TUG1 was elevated in proinflammatory-activated microglia and positively correlated with the levels of inflammatory factors. The expression of anti-inflammatory cytokines such as IL-4, Arg1, CD206, and Ym1 were decreased when induced with LPS/IFN-γ. However, this decrease was reversed by the treatment with 2-DG. Silencing of GAPDH led to an increase in the expression of TUG1 and inflammatory factors. TUG1 knockout (TUG1KO) inhibited the expression of glycolytic key enzymes and promoted the expression of oxidative phosphorylation key enzymes, shifting the metabolic profile of activated microglia from glycolysis to oxidative phosphorylation. Additionally, TUG1KO reduced the accumulation of metabolites, facilitating the restoration of the tricarboxylic acid cycle and enhancing oxidative phosphorylation in microglia. Furthermore, the downregulation of TUG1 was found to reduce the expression of both proinflammatory and anti-inflammatory cytokines under normal conditions. Interestingly, when induced with LPS/IFN-γ, TUG1 downregulation showed a potentially beneficial effect on microglia in terms of inflammation. Downregulation of TUG1 expression inhibits glycolysis and facilitates the shift of microglial glucose metabolism from glycolysis to oxidative phosphorylation, promoting their transformation towards an anti-inflammatory phenotype and exerting anti-inflammatory effects in BV2.

Long Non-Coding RNA TUG1 Gene Polymorphism and TUG1 Expression Level as Molecular Biomarkers of Systemic Lupus Erythematosus and Lupus Nephritis

Long non-coding RNA (lncRNA) TUG1 acts as a proto-oncogene, allowing the proliferation of tumor cells, and it has been related to inflammation. Therefore, we aimed in this study to investigate for the first time the role of TUG1 gene polymorphism and the TUG1 level as biomarkers in systemic lupus erythematosus (SLE) and their link to lupus nephritis 145 SLE. A total of 145 healthy controls were subjected to clinical and laboratory evaluation. The disease activity was assessed by the SLE disease activity index (SLEDAI) score. SLE patients were divided into two subgroups according to the presence of lupus nephritis. The TUG1 gene polymorphisms rs5749201 and rs886471 were determined by Sanger sequencing, and TUG1 expression was assessed by qRT-PCR. There was a significant increase in the risk of SLE AA, TA, dominant genotypes, and the A allele of rs5749201 (p < 0.001) by 4.9-, 10.1-, 6.5-, and 2.5-fold in comparison to the relative control. GG and TG, dominant genotypes and the G allele of rs886471 (p < 0.01) increased the risk by 5.09-, 11.9-, 6.5-, and 2.6-fold. AA, A allele, dominant and recessive rs5749201genotypes increased the risk of lupus nephritis by 16.6-, 7.4-, 7.1-, and 12.2-fold, respectively (p < 0.05). GG, dominant and recessive genotypes, and the G allele of rs886471 increased the risk of lupus nephritis by 17.04-, 7.8-, 9.4-, and 6.08-fold, respectively (p < 0.05). Additionally, the AG haplotype increased the risk of SLE and lupus nephritis by 2.7- and 7.8-fold, respectively. The AA rs5749201 and GG rs886471 variants are significantly associated with more severe disease (p < 0.001). TUG1 expression was significantly higher in SLE than in the control and in the lupus nephritis than in non-lupus nephritis cases (p < 0.05). Interestingly, AA rs5749201 and GG rs886471 were significantly associated with higher TUG1 levels (p < 0.001). It was also found that AA rs5749201 and high SLEDAI were predictors of lupus nephritis. Overall, our findings illustrated for the first time that TUG1 gene rs5749201 and rs886471 variants were associated with increased risk of SLE, more severe disease, and lupus nephritis, and the TUG1 level could be used as a diagnostic biomarker of SLE and lupus nephritis.

Diagnostic and Prognostic Value of Deregulated Circulating Long Non-coding RNA TUG1 in Elderly Patients with Severe Pneumonia

To investigate the expression pattern of long non-coding RNA TUG1 in elderly patients with severe community-acquired pneumonia (sCAP) and evaluate its diagnostic and prognostic value for sCAP. Serum TUG1 levels were detected in 130 sCAP patients and 122 healthy volunteers via qRT-PCR method. The receiver operating characteristic (ROC) curve and k-M plot were drawn for the diagnostic and prognostic value evaluation. A diminished trend of TUG1 was detected in the serum of sCAP cases, and negatively correlated with the concentration of TNF-α, CRP, suPAR and sTREM-1. Among the 130 cases, 30 cases died from sCAP within 30 days after admission. Serum TUG1 had the diagnostic value for 30-day mortality prediction with the AUC of 0.823. In the non-survival group, more cases had old age, high CURB score and PSI score. K-M plot demonstrated that cases with low TUG1 levels showed poor survival than those carrying high TUG1 levels. Serum TUG1 was an independent risk factor for death in elderly patients with sCAP within 30 days after admission. Serum TUG1 was at low expression in sCAP patients, and it had the predictive value for the clinical prognosis of elderly sCAP patients.

Protective effect of hepatocyte-enriched lncRNA-Mir122hg by promoting hepatocyte proliferation in acute liver injury

Some long noncoding RNAs (lncRNAs), which harbor microRNAs in their gene sequence and are also known as microRNA host gene derived lncRNAs (lnc-MIRHGs), play a dominant role alongside miRNAs, or both perform biological functions synergistically or independently. However, only a small number of lnc-MIRHGs have been identified. Here, multiple liver injury datasets were analyzed to screen and identify the target lncRNA Mir122hg. Mir122hg was mainly enriched in liver tissues with human-mouse homology. In both CCl₄-induced acute liver injury and Dgal/LPS-induced fulminant liver failure in mice, Mir122hg was sharply downregulated at the early stage, while a subsequent significant increase was only found in the CCl₄ group with liver recovery. Overexpression and silencing assays confirmed that Mir122hg played a protective role in acute injury by promoting hepatocyte proliferation in vivo and in vitro. Consistent with the results of gene enrichment analysis, Mir122hg binding to C/EBPα affected its transcriptional repression, promoted gene transcription of downstream chemokines, Cxcl2, Cxcl3, and Cxcl5, and exerted pro-proliferative effects on hepatocytes through activation of the AKT/GSK-3β/p27 signaling pathway by CXC/CXCR2 complexes. This study identifies a novel lncRNA with protective effects in acute liver injury and demonstrates that the binding of Mir122hg-C/EBPα promotes hepatocyte proliferation via upregulation of CXC chemokine and activation of AKT signaling.

Role of Long Noncoding RNAs in the Regulation of Cellular Immune Response and Inflammatory Diseases

Long noncoding RNAs (lncRNAs) are recently discovered genetic regulatory molecules that regulate immune responses and are closely associated with the occurrence and development of various diseases, including inflammation, in humans and animals. Under specific physiological conditions, lncRNA expression varies at the cell or tissue level, and lncRNAs can bind to specific miRNAs, target mRNAs, and target proteins to participate in certain processes, such as cell differentiation and inflammatory responses, via the corresponding signaling pathways. This review article summarizes the regulatory role of lncRNAs in macrophage polarization, dendritic cell differentiation, T cell differentiation, and endothelial and epithelial inflammation. In addition, it describes the molecular mechanism of lncRNAs in acute kidney injury, hepatitis, inflammatory injury of the lung, osteoarthritis, mastitis, and neuroinflammation to provide a reference for the molecular regulatory network as well as the genetic diagnosis and treatment of inflammatory diseases in humans and animals.