LncRNA MEG3 functions as a ceRNA in regulating hepatic lipogenesis by competitively binding to miR-21 with LRP6

A comprehensive review of miR-21 in liver disease: Big impact of little things

microRNAs (miRNAs), a class of non-coding RNA with 20-24 nucleotides, are defined as the powerful regulators for gene expression. miR-21 is a multifunctional miRNA enriched in the circulatory system and multiple organs, which not only serves as a non-invasive biomarker in disease diagnosis, but also participates in many cellular activities. In various chronic liver diseases, the increase of miR-21 affects glycolipid metabolism, viral infection, inflammatory and immune cell activation, hepatic stellate cells activation and tissue fibrosis, and autophagy. Moreover, miR-21 is also a liaison in the deterioration of chronic liver disease to hepatocellular carcinoma (HCC), and it impacts on cell proliferation, apoptosis, migration, invasion, angiogenesis, immune escape, and epithelial-mesenchymal transformation by regulating target genes expression in different signaling pathways. In current research on miRNA therapy, some natural products can exert the hepatoprotective effects depending on the inhibition of miR-21 expression. In addition, miR-21-based therapeutic also play a role in regulating intracellular miR-21 levels and enhancing the efficacy of chemotherapy drugs. Herein, we systemically summarized the recent progress of miR-21 on biosynthesis, biomarker function, molecular mechanism and miRNA therapy in chronic liver disease and HCC, and looked forward to outputting some information to enable it from bench to bedside.

Long non-coding RNAs as modulators and therapeutic targets in non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the world, with epidemiological studies indicating a 25% prevalence. NAFLD is considered to be a progressive disease that progresses from simple hepatic steatosis to non-alcoholic steatohepatitis (NASH), then to liver fibrosis, and finally to cirrhosis or hepatocellular carcinoma (HCC). Existing research has mostly elucidated the etiology of NAFLD, yet its particular molecular processes remain uncertain. Long non-coding RNAs (LncRNAs) have been linked in a wide range of biological processes in recent years, with the introduction of microarray and high-throughput sequencing technologies, and previous studies have established their tight relationship with several stages of NAFLD development. Existing studies have shown that lncRNAs can regulate the signaling pathways related to hepatic lipid metabolism, NASH, NASH-related fibrosis and HCC. This review aims to provide a basic overview of NAFLD and lncRNAs, summarize and describe the mechanisms of lncRNAs action involved in the development of NAFLD, and provide an outlook on the future of lncRNAs-based therapy for NAFLD.

Competitive adsorption of microRNA-532-3p by circular RNA SOD2 activates Thioredoxin Interacting Protein/NLR family pyrin domain containing 3 pathway and promotes pyroptosis of non-alcoholic fatty hepatocytes

OBJECTIVE

There is a growing body of evidence indicating that pyroptosis, a programmed cell death mechanism, plays a crucial role in the exacerbation of inflammation and fibrosis in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Circular RNAs (circRNAs), functioning as vital regulators within NAFLD, have been shown to mediate the process of cell pyroptosis. This study aims to elucidate the roles and mechanisms of circRNAs in NAFLD.

METHODS

Utilizing a high-fat diet (HFD)-induced rat model for in vivo experimentation and hepatocytes treated with palmitic acid (PA) for in vitro models, we identified circular RNA SOD2 (circSOD2) as our circRNA of interest through analysis with the circMine database. The expression levels of associated genes and pyroptosis-related proteins were determined using quantitative real-time polymerase chain reaction and Western blotting, alongside immunohistochemistry. Serum liver function markers, cellular inflammatory cytokines, malondialdehyde, lactate dehydrogenase levels, and mitochondrial membrane potential, were assessed using enzyme-linked immunosorbent assay, standard assay kits, or JC-1 staining. Flow cytometry was employed to detect pyroptotic cells, and lipid deposition in liver tissues was observed via Oil Red O staining. The interactions between miR-532-3p/circSOD2 and miR-532-3p/Thioredoxin Interacting Protein (TXNIP) were validated through dual-luciferase reporter assays and RNA immunoprecipitation experiments.

RESULTS

Our findings demonstrate that, in both in vivo and in vitro NAFLD models, there was an upregulation of circSOD2 and TXNIP, alongside a downregulation of miR-532-3p. Mechanistically, miR-532-3p directly bound to the 3'-UTR of TXNIP, thereby mediating inflammation and cell pyroptosis through targeting the TXNIP/NLR family pyrin domain containing 3 (NLRP3) inflammasome signaling pathway. circSOD2 directly interacted with miR-532-3p, relieving the suppression on the TXNIP/NLRP3 signaling pathway. Functionally, the knockdown of circSOD2 or TXNIP improved hepatocyte pyroptosis; the deletion of miR-532-3p reversed the effects of circSOD2 knockdown, and the deletion of TXNIP reversed the effects of circSOD2 overexpression. Furthermore, the knockdown of circSOD2 significantly mitigated the progression of NAFLD in vivo.

CONCLUSION

circSOD2 competitively sponges miR-532-3p to activate the TXNIP/NLRP3 inflammasome signaling pathway, promoting pyroptosis in NAFLD.

Two sides of the same coin: Non-alcoholic fatty liver disease and atherosclerosis

The prevalence of non-alcoholic fatty liver disease (NAFLD) and atherosclerosis remain high, which is primarily due to widespread adoption of a western diet and sedentary lifestyle. NAFLD, together with advanced forms of this disease such as non-alcoholic steatohepatitis (NASH) and cirrhosis, are closely associated with atherosclerotic-cardiovascular disease (ASCVD). In this review, we discussed the association between NAFLD and atherosclerosis and expounded on the common molecular biomarkers underpinning the pathogenesis of both NAFLD and atherosclerosis. Furthermore, we have summarized the mode of function and potential clinical utility of existing drugs in the context of these diseases.

A crosstalk between epigenetic modulations and non-alcoholic fatty liver disease progression

Non-alcoholic fatty liver disease (NAFLD) has recently emerged as a major public health concern worldwide due to its rapidly rising prevalence and its potential to progress into end-stage liver disease. While the precise pathophysiology underlying NAFLD remains incompletely understood, it is strongly associated with various environmental triggers and other metabolic disorders. Epigenetics examines changes in gene expression that are not caused by alterations in the DNA sequence itself. There is accumulating evidence that epigenetics plays a key role in linking environmental cues to the onset and progression of NAFLD. Our understanding of how epigenetic mechanisms contribute to NAFLD pathophysiology has expanded considerably in recent years as research on the epigenetics of NAFLD has developed. This review summarizes recent insights into major epigenetic processes that have been implicated in NAFLD pathogenesis including DNA methylation, histone acetylation, and microRNAs that have emerged as promising targets for further investigation. Elucidating epigenetic mechanisms in NAFLD may uncover novel diagnostic biomarkers and therapeutic targets for this disease. However, many questions have remained unanswered regarding how epigenetics promotes NAFLD onset and progression. Additional studies are needed to further characterize the epigenetic landscape of NAFLD and validate the potential of epigenetic markers as clinical tools. Nevertheless, an enhanced understanding of the epigenetic underpinnings of NAFLD promises to provide key insights into disease mechanisms and pave the way for novel prognostic and therapeutic approaches.

The impact and role of identified long noncoding RNAs in nonalcoholic fatty liver disease: A narrative review

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide, but its mechanism and pathophysiology remain unclear. Long noncoding RNAs (lncRNAs) may exert a vital influence on regulating various biological functions in NAFLD.

METHODS

The databases such as Google Scholar, PubMed, and Medline were searched using the following keywords: nonalcoholic fatty liver disease, nonalcoholic fatty liver disease, NAFLD, nonalcoholic steatohepatitis, nonalcoholic steatohepatitis, NASH, long noncoding RNAs, and lncRNAs. Considering the titles and abstracts, unrelated studies were excluded. The authors evaluated the full texts of the remaining studies.

RESULTS

We summarized the current knowledge of lncRNAs and the main signaling pathways of lncRNAs involved in NAFLD explored in recent years. As a heterogeneous group of noncoding RNAs (ncRNAs), lncRNAs play crucial roles in biological processes underlying the pathophysiology of NAFLD. The mechanisms, particularly those associated with the regulation of the expression and activities of lncRNAs, play important roles in NAFLD.

CONCLUSION

A better comprehension of the mechanism controlled by lncRNAs in NAFLD is necessary for the identification of novel therapeutic targets for drug development and improved, noninvasive methods for diagnosis.

LncRNA and circRNA in Patients with Non-Alcoholic Fatty Liver Disease: A Systematic Review

Non-alcoholic fatty liver disease (NAFLD) is currently the most common cause of chronic liver disease worldwide. Early identification and prompt treatment are critical to optimize patient management and improve long-term prognosis. Long non-coding RNA (lncRNA) and circular RNA (circRNA) are recently emerging non-coding RNAs, and are highly stable and easily detected in the circulation, representing a promising non-invasive approach for predicting NAFLD. A literature search of the Pubmed, Embase, Web of Science, and Cochrane Library databases was performed and 36 eligible studies were retrieved, including 18 on NAFLD, 13 on nonalcoholic steatohepatitis (NASH), and 11 on fibrosis and/or cirrhosis. Dynamic changes in lncRNA expression were associated with the occurrence and progression of NAFLD, among which lncRNA NEAT1, MEG3, and MALAT1 exhibited great potential as biomarkers for NAFLD. Moreover, mitochondria-located circRNA SCAR can drive metaflammation and its inhibition might be a promising therapeutic target for NASH. In this systematic review, we highlight the great potential of lncRNA/circRNA for early diagnosis and progression assessment of NAFLD. To further verify their clinical value, large-cohort studies incorporating lncRNA and circRNA expression both in liver tissue and blood should be conducted. Additionally, detailed studies on the functional mechanisms of NEAT1, MEG3, and MALAT1 will be essential for elucidating their roles in diagnosing and treating NAFLD, NASH, and fibrosis.

The role of long non-coding RNAs in carbohydrate and fat metabolism in the liver

The metabolism of carbohydrates and lipids (fat) in the liver is closely interconnected both in physiological conditions and in pathology. This relationship in the body is possible due to the regulation by many factors, including epigenetic ones. Histone modifications, DNA methylation, and non-coding RNAs are considered to be the main epigenetic factors. Non-coding RNAs (ncRNAs) refers to ribonucleic acid (RNA) molecules that do not code for a protein. They cover a huge number of RNA classes and perform a wide range of biological functions such as regulating gene expression, protecting the genome from exogenous DNA, and directing DNA synthesis. One such class of ncRNAs that has been extensively studied are long non-coding RNAs (lncRNAs). The important role of lncRNAs in the formation and maintenance of normal homeostasis of biological systems, as well as participation in many pathological processes, has been proven. The results of recent studies indicate the importance of lncRNAs in lipid and carbohydrate metabolism. Modifications of lncRNAs expression can lead to disruption of biological processes in tissues, including fat and protein, such as adipocyte proliferation and differentiation, inflammation, and insulin resistance. Further study of lncRNAs made it possible to partly determine the regulatory mechanisms underlying the formation of an imbalance in carbohydrate and fat metabolism individually and in their relationship, and the degree of interaction between different types of cells involved in this process. This review will focus on the function of lncRNAs and its relation to hepatic carbohydrate and fat metabolism and related diseases in order to elucidate the underlying mechanisms and prospects for studies with lncRNAs.

LncRNA HDAC11-AS1 Suppresses Atherosclerosis by Inhibiting HDAC11-Mediated Adropin Histone Deacetylation

LncRNA HDAC11-AS1 (HDAC11-AS1) is the natural antisense transcript of HDAC11, a key enzyme for DNA histone deacetylation. We evaluated the role of HDAC11-AS1 in atherosclerosis. In this research, we found that HDAC11-AS1 ameliorated blood lipid levels and atherosclerosis in high fat-dieted apoE-/- mice by regulating HDAC11 negatively. The change in blood lipid levels is related to the expression of LPL, which is enhanced by HDAC11-AS1 through regulating adropin histone deacetylation in vitro and in vivo. In conclusion, HDAC11-AS1 plays an anti-atherogenic role through adropin to induce LPL expressions, thereby enhancing TG metabolism. The results are valuable for the further development of HDAC11-AS1 and its clinical applications. It provides a new clinical therapeutic target for cardiovascular disease treatment.

Noncoding RNAs as additional mediators of epigenetic regulation in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most common cause of chronic liver disorder worldwide. It represents a spectrum that includes a continuum of different clinical entities ranging from simple steatosis to nonalcoholic steatohepatitis, which can evolve to cirrhosis and in some cases to hepatocellular carcinoma, ultimately leading to liver failure. The pathogenesis of NAFLD and the mechanisms underlying its progression to more pathological stages are not completely understood. Besides genetic factors, evidence indicates that epigenetic mechanisms occurring in response to environmental stimuli also contribute to the disease risk. Noncoding RNAs (ncRNAs), including microRNAs, long noncoding RNAs, and circular RNAs, are one of the epigenetic factors that play key regulatory roles in the development of NAFLD. As the field of ncRNAs is rapidly evolving, the present review aims to explore the current state of knowledge on the roles of these RNA species in the pathogenesis of NAFLD, highlight relevant mechanisms by which some ncRNAs can modulate regulatory networks implicated in NAFLD, and discuss key challenges and future directions facing current research in the hopes of developing ncRNAs as next-generation non-invasive diagnostics and therapies in NAFLD and subsequent progression to hepatocellular carcinoma.

Noncoding RNAs Associated with PPARs in Etiology of MAFLD as a Novel Approach for Therapeutics Targets

Background. Metabolic associated fatty liver disease (MAFLD) is a complex disease that results from the accumulation of fat in the liver. MAFLD is directly associated with obesity, insulin resistance, diabetes, and metabolic syndrome. PPARγ ligands, including pioglitazone, are also used in the management of this disease. Noncoding RNAs play a critical role in various diseases such as diabetes, obesity, and liver diseases including MAFLD. However, there is no adequate knowledge about the translation of using these ncRNAs to the clinics, particularly in MAFLD conditions. The aim of this study was to identify ncRNAs in the etiology of MAFLD as a novel approach to the therapeutic targets. Methods. We collected human and mouse MAFLD gene expression datasets available in GEO. We performed pathway enrichment analysis of total mRNAs based on KEGG repository data to screen the most potential pathways in the liver of MAFLD human subjects and mice model, and analyzed pathway interconnections via ClueGO. Finally, we screened disease causality of the MAFLD ncRNAs, which were associated with PPARs, and then discussed the role of revealed ncRNAs in PPAR signaling and MAFLD. Results. We found 127 ncRNAs in MAFLD which 25 out of them were strongly validated before for regulation of PPARs. With a polypharmacology approach, we screened 51 ncRNAs which were causal to a subset of diseases related to MAFLD. Conclusion. This study revealed a subset of ncRNAs that could help in more clear and guided designation of preclinical and clinical studies to verify the therapeutic application of the revealed ncRNAs by manipulating the PPARs molecular mechanism in MAFLD.

Characterization of differentially expressed and lipid metabolism-related lncRNA-mRNA interaction networks during the growth of liver tissue through rabbit models

Background

Characterization the long non-coding RNAs (lncRNAs) and their regulated mRNAs involved in lipid metabolism during liver growth and development is of great value for discovering new genomic biomarkers and therapeutic targets for fatty liver and metabolic syndrome.

Materials and methods

Liver samples from sixteen rabbit models during the four growth stages (birth, weaning, sexual maturity, and somatic maturity) were used for RNA-seq and subsequent bioinformatics analyses. Differentially expressed (DE) lncRNAs and mRNAs were screened, and the cis/trans-regulation target mRNAs of DE lncRNAs were predicted. Then the function enrichment analyses of target mRNAs were performed through Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, respectively. The target protein interaction (PPI) and lncRNA-mRNA co-expression networks were constructed using string version 11.0 platform and R Stats. Finally, six lncRNAs and six mRNAs were verified taking RT-qPCR.

Results

Liver Oil Red O detection found that the liver showed time-dependent accumulation of lipid droplets. 41,095 lncRNAs, 30,744 mRNAs, and amount to 3,384 DE lncRNAs and 2980 DE mRNAs were identified from 16 cDNA sequencing libraries during the growth of liver. 689 out of all DE lncRNAs corresponded to 440 DE mRNAs by cis-regulation and all DE mRNAs could be regulated by DE lncRNAs by trans-regulation. GO enrichment analysis showed significant enrichment of 892 GO terms, such as protein binding, cytosol, extracellular exsome, nucleoplasm, and oxidation-reduction process. Besides, 52 KEGG pathways were significantly enriched, including 11 pathways of lipid metabolism were found, like Arachidonic acid metabolism, PPAR signaling pathway and Biosynthesis of unsaturated fatty acids. After the low expression DE mRNAs and lncRNAs were excluded, we further obtained the 54 mRNAs were regulated by 249 lncRNAs. 351 interaction pairs were produced among 38 mRNAs and 215 lncRNAs through the co-expression analysis. The PPI network analysis found that 10 mRNAs such as 3β-Hydroxysteroid-Δ24 Reductase (DHCR24), lathosterol 5-desaturase (SC5D), and acetyl-CoA synthetase 2 (ACSS2) were highly interconnected hub protein-coding genes. Except for MSTRG.43041.1, the expression levels of the 11 genes by RT-qPCR were the similar trends to the RNA-seq results.

Conclusion

The study revealed lncRNA-mRNA interation networks that regulate lipid metabolism during liver growth, providing potential research targets for the prophylaxis and treatment of related diseases caused by liver lipid metabolism disorders.

Long Noncoding RNAs That Function in Nutrition: Lnc-ing Nutritional Cues to Metabolic Pathways

Long noncoding RNAs (lncRNAs) are sensitive to changing environments and play key roles in health and disease. Emerging evidence indicates that lncRNAs regulate gene expression to shape metabolic processes in response to changing nutritional cues. Here we review various lncRNAs sensitive to fasting, feeding, and high-fat diet in key metabolic tissues (liver, adipose, and muscle), highlighting regulatory mechanisms that trigger expression changes of lncRNAs themselves, and how these lncRNAs regulate gene expression of key metabolic genes in specific cell types or across tissues. Determining how lncRNAs respond to changes in nutrition is critical for our understanding of the complex downstream cascades following dietary changes and can shape how we treat metabolic disease. Furthermore, investigating sex biases that might influence lncRNA-regulated responses will likely reveal contributions toward the observed disparities between the sexes in metabolic diseases.

Research Progress on Long Noncoding RNAs and N6-Methyladenosine in Hepatocellular Carcinoma

N6-methyladenosine (m6A) is an epigenetic modification that widely exists in long noncoding RNAs (lncRNAs) and is involved in the regulation of oncogenes or tumor suppressor genes that form complex enzymes to affect the occurrence of tumors. The abnormal modification of m6A methylation can alter the overall m6A level and thus contribute to the malignant biological behaviors of hepatocellular carcinoma (HCC). LncRNAs related to m6A methylation are involved in lipogenesis, the proliferation, migration and invasion of HCC cells, the stemness of tumor cells and sorafenib resistance. In this review, we systematically elaborated the occurrence mechanism of lncRNA and m6A methylation modification in HCC and the effect of m6A methylation modification of lncRNA on the occurrence of HCC, suggesting that the combination of m6A methylation modification and lncRNA will be more meaningful as molecular markers or prognostic markers. It is helpful to provide further ideas for exploring the pathogenesis of HCC and identifying new targets for HCC treatment and diagnosis and achieve precise individual treatment of liver cancer.

A novel lncRNA RP11-386G11.10 reprograms lipid metabolism to promote hepatocellular carcinoma progression

Objective

Emerging studies suggest that long non-coding RNAs (lncRNAs) play crucial roles in hepatocellular carcinoma (HCC). A rapidly increasing number of studies have shown that metabolic changes including lipid metabolic reprogramming play a significant role in the progression of HCC. But it remains to be elucidated how lncRNAs affect tumor cell metabolism.

Methods

Through analysis and screening of The Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC) dataset, we found a novel lncRNA RP11-386G11.10 was overexpressed, related to prognosis, conserved and non-protein-coding in HCC and related to poor prognosis. Then, CCK-8, colony formation, Transwell invasion, wound healing assays were performed and nude mouse subcutaneous tumour formation and lung metastasis models were established to explore the effect of RP11-386G11.10 on HCC tumour growth and metastasis. Chromatography-mass spectrometry (GC-MS) and Nile red staining detected the effect of RP11-386G11.10 on lipid metabolism in HCC. Mechanistically, we clarified the RP11-386G11.10/miR-345-3p/HNRNPU signalling pathway through dual luciferase reporter, RNA immunoprecipitation (RIP) and chromatin immunoprecipitation (ChIP) assays and identified ZBTB7A as a transcription factor of RP11-386G11.10.

Results

RP11-386G11.10 was overexpressed in HCC and positively correlated with tumour size, TNM stage, and poor prognosis in HCC patients. RP11-386G11.10 promoted the proliferation and metastasis of HCC cells in vitro and in vivo. Mechanistically, RP11-386G11.10 acted as a competing endogenous RNA (ceRNA) for miR-345-3p to regulate the expression of HNRNPU and its downstream lipogenic enzymes, leading to lipid accumulation in HCC cells and promoting their growth and metastasis. In addition, we identified ZBTB7A as a transcription factor of RP11-386G11.10. Moreover, HNRNPU promoted the expression of ZBTB7A in HCC cells, thereby increasing the transcriptional activity of RP11-386G11.10, and forming a positive feedback loop, ultimately leading continuous lipid accumulation, growth and metastasis in HCC cells.

Conclusions

Our results indicated that the lncRNA RP11-386G11.10 was a novel oncogenic lncRNA that was strongly correlated with the poor prognosis of HCC. The ZBTB7A-RP11-386G11.10-HNRNPU positive feedback loop promoted the progression of HCC by regulating lipid anabolism. RP11-386G11.10 may become a new diagnostic and prognostic biomarker and therapy target for HCC.

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LncRNA RP11-386G11.10 was up-regulated in HCC.

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Overexpression of lncRNA RP11-386G11.10 promoted the proliferation, metastasis of HCC cells in vivo and in vitro.

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We confirmed that regulation of HNRNPU expression by RP11-286H15.1 resulted in lipid accumulation in HCC cells.

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HNRNPU forms a ZBTB7A- RP11-386G11.10 -HNRNPU positive feedback loop by promoting mRNA stability of ZBTB7A.

The Association of MEG3 lncRNA with Nuclear Speckles in Living Cells

Nuclear speckles are nuclear bodies containing RNA-binding proteins as well as RNAs including long non-coding RNAs (lncRNAs). Maternally expressed gene 3 (MEG3) is a nuclear retained lncRNA found to associate with nuclear speckles. To understand the association dynamics of MEG3 lncRNA with nuclear speckles in living cells, we generated a fluorescently tagged MEG3 transcript that could be detected in real time. Under regular conditions, transient association of MEG3 with nuclear speckles was observed, including a nucleoplasmic fraction. Transcription or splicing inactivation conditions, known to affect nuclear speckle structure, showed prominent and increased association of MEG3 lncRNA with the nuclear speckles, specifically forming a ring-like structure around the nuclear speckles. This contrasted with metastasis-associated lung adenocarcinoma (MALAT1) lncRNA that is normally highly associated with nuclear speckles, which was released and dispersed in the nucleoplasm. Under normal conditions, MEG3 dynamically associated with the periphery of the nuclear speckles, but under transcription or splicing inhibition, MEG3 could also enter the center of the nuclear speckle. Altogether, using live-cell imaging approaches, we find that MEG3 lncRNA is a transient resident of nuclear speckles and that its association with this nuclear body is modulated by the levels of transcription and splicing activities in the cell.

lncRNA MEG3 restrained the M1 polarization of microglia in acute spinal cord injury through the HuR/A20/NF-κB axis

The M1 polarization of microglia and neuroinflammation restrict the treatment of acute spinal cord injury (ASCI), and long non‐coding ribonucleic acid (lncRNA) maternally expressed gene 3 (MEG3) expression is lessened in ASCI. However, the function and mechanism of lncRNA MEG3 in the M1 polarization of microglia and neuroinflammation in ASCI are unclear. The expressions of lncRNA MEG3 in ASCI mouse spinal cord tissues and lipopolysaccharide (LPS)‐treated primary microglia and BV2 cells were quantified through a quantitative real‐time polymerase chain reaction. In‐vitro assays were conducted to explore the function of lncRNA MEG3 in the M1 polarization of microglia and neuroinflammation in ASCI. RNA degradation, RNA immunoprecipitation, RNA pull‐down, cycloheximide‐chase, and ubiquitination analyses were carried out to probe into the mechanism of lncRNA MEG3 in the M1 polarization of microglia and neuroinflammation in ASCI. The lncRNA MEG3 expression was lessened in the ASCI mouse spinal cord tissues and LPS‐treated primary microglia and BV2 cells, and the overexpression of lncRNA MEG3 restrained the M1 polarization of microglia and the neuroinflammation by regulating the NF‐κB signaling pathway. For the investigation of the potential mechanism of such, the overexpression of lncRNA MEG3 restrained the M1 polarization of microglia through the HuR/A20/NF‐κB axis and boosted the motor function recovery and neuroinflammation relief in the mice with SCI. The overexpression of lncRNA MEG3 restrained the M1 polarization of microglia through the HuR/A20/NF‐κB axis.

Long non-coding RNA GAS5 contributes to the progression of nonalcoholic fatty liver disease by targeting the microRNA-29a-3p/NOTCH2 axis

Long non-coding RNAs (lncRNAs) have been widely recognized as critical players in the development of nonalcoholic fatty liver disease (NAFLD), one of the most prevalent liver diseases globally. In this study, we established a HFD-induced NAFLD mouse model and explored the role of lncRNA GAS5 in NAFLD progression and its possible underlying mechanisms. We showed that NAFLD activity score was elevated in the HFD mice. GAS5 knockdown attenuated HFD-induced hepatic steatosis and lipid accumulation and reduced NAFLD activity score in HFD mice. In addition, GAS5 knockdown reduced serum triglyceride cholesterol levels and inhibited alanine aminotransferase and aspartate aminotransferase activities in HFD mice. Moreover, GAS5 overexpression enhanced NOTCH2 levels in liver cells and promoted NAFLD progression by sponging miR-29a-3p in vivo. Furthermore, miR-29a-3p inhibited NAFLD progression by targeting NOTCH2 in vivo. Overall, our results indicated that GAS5 acts as a sponge of miR-29a-3p to increase NOTCH2 expression and facilitate NAFLD progression by targeting the miR-29a-3p/NOTCH2 axis and demonstrated a new GAS5-mediated mechanism underlying NAFLD development, suggesting that GAS5 could be a potential therapeutic target of NAFLD.

Abbreviations: Alanine aminotransferase: ALT; Aspartate aminotransferase: AST; Enzyme linked immunosorbent assay: ELISA; Hepatocellular carcinoma: HCC; High-fat diet: HFD; Long non-coding RNA: Lnc RNA; Long non-coding RNA GAS5: GAS5; MicroRNAs: MiRNAs; Nonalcoholic fatty liver disease: NAFLD; Quantitative reverse transcription PCRs: RT-qPCRs; siRNA negative control: si-NC; Total cholesterol: TC; Triglyceride: TG

LncRNA MEG3 up-regulates SIRT6 by ubiquitinating EZH2 and alleviates nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a global health threat. Here, we presented the significant role of a novel signaling axis comprising long non-coding RNA maternally expressed gene 3 (MEG3), enhancer of zeste homolog 2 (EZH2), and sirtuin 6 (SIRT6) in controlling lipid accumulation, inflammation, and the progression of NAFLD. Mice fed with high-fat diet (HFD) were established as in vitro and in vivo NAFLD models, respectively. Lipid accumulation was measured by oil red O staining and assays for triglycerides or cholesterol. Inflammation was examined by ELISA for pro-inflammatory cytokines. Gene expressions were examined by RT-qPCR or Western blot. Interactions between key signaling molecules were examined by combining expressional analysis, RNA immunoprecipitation, cycloheximide stability assay, co-immunoprecipitation, and chromatin immunoprecipitation. MEG3 level was reduced in FFA-challenged hepatocytes or liver from HFD-fed mice, and the reduction paralleled the severity of NAFLD in clinic. Overexpressing MEG3 suppressed FFA-induced lipid accumulation or inflammation in hepatocytes. By promoting the ubiquitination and degradation of EZH2, MEG3 upregulated SIRT6, an EZH2 target. SIRT6 essentially mediated the protective effects of MEG3 in hepatocytes. Consistently, overexpressing MEG3 alleviated HFD-induced NAFLD in vivo. By controlling the expressions of genes involved in lipid metabolism and inflammation, the MEG3/EZH2/SIRT6 axis significantly suppressed lipid accumulation and inflammation in vitro, and NAFLD development in vivo. Therefore, boosting MEG3 level may benefit the treatment of NAFLD.

Long non-coding RNA TPTEP1 exerts inhibitory effects on hepatocellular carcinoma by impairing microRNA-454-3p-mediated DLG5 downregulation

BACKGROUND

Hepatocellular carcinoma (HCC) is usually diagnosed at late stages, making it the second cause of malignancy-related death across the world. Long noncoding RNAs (lncRNAs) are of significance to tumorigenesis, highly suggestive of their functional roles as novel biomarkers for cancer therapy. The current study investigated the specific role of lncRNA TPTE pseudogene 1 (TPTEP1) in HCC.

METHODS

Expression of lncRNA TPTEP1, microRNA-454-3p (miR-454-3p) and discs large homolog 5 (DLG5) was determined in tissues samples from the recruited patients with HCC. Cell proliferation, migration and invasion assays were performed to determine effects of lncRNA TPTEP1, miR-454-3p and DLG5 on the malignant phenotype of tumor cells. Finally, the mouse HCC model was also established to disclose the tumor suppressor effects of lncRNA TPTEP1 in vivo.

RESULTS

LncRNA TPTEP1 was downregulated both in HCC cells and tissues, and played a negative regulatory role in HCC cell proliferation, migration and invasion. Mechanistically, lncRNA TPTEP1 competitively bound to miR-454-3p, thereby upregulating its endogenous target DLG5. Moreover, lncRNA TPTEP1 hindered activation of the protein kinase B signaling pathway, causing inhibited malignant phenotypes of HCC cells. Also, lncRNA TPTEP1 suppressed tumor growth and extrahepatic metastasis (lung) via miR-454-3p/DLG5 axis.

CONCLUSION

Taken together, this research revealed a concrete mechanism of lncRNA TPTEP1 in HCC.

Lnc-hipk1 inhibits mouse adipocyte apoptosis as a sponge of miR-497

Noncoding RNAs (ncRNAs) such as microRNAs (miRNAs), long noncoding RNAs (lncRNA), and circular RNAs are closely related to the biological processes related to obesity. As a miRNA that widely present in different cell types, miR497 is proved to be involved in cell development. However, research on the role of miR-497 as a key factor in regulating the development of adipocytes is still in gap. The role of miR-497 in the apoptosis and proliferation of mouse-derived adipocytes was detected by RNA-seq analysis, RT-qPCR, Western blot, immunofluorescence, and dual-luciferase reporter assay. Using miR-497 mimics to treat 3T3-L1 cells, we found that miR-497 targeted Bcl-2 to promote adipocyte apoptosis through the mitochondrial pathway, and this effect was consistent in the apoptosis model composed of palmitic acid (PA) and hydrogen peroxide (H₂ O₂ ). LncRNA homeodomain-interacting protein kinase 1 (lnc-hipk1) sponged miR-148b to weaken its silencing of Bcl-2, forming the competitive endogenous RNAs (CeRNAs) regulatory network. Furthermore, overexpression of lnc-hipk1 inhibited the apoptosis of adipocytes by targeting miR-497/Bcl-2. Co-treatment of miR-497 and lnc-hipk1 showed that lnc-hipk1 reversed the apoptosis of adipocytes caused by miR-497 overexpression. And in vivo experiments further confirmed that this effect was also achieved by the CeRNA system of lnc-hipk1/miR-497/Bcl-2. In summary, lnc-hipk1 targets miR-497/Bcl-2 to regulate adipocyte apoptosis through the mitochondrial pathway. This research enriches the research content of ncRNAs and CeRNA in adipocyte development, and provides new targets for the treatment of obesity and other metabolic syndromes.

Nonalcoholic Fatty Liver Disease (NAFLD): Pathogenesis and Noninvasive Diagnosis

The global prevalence of nonalcoholic fatty liver disease (NAFLD) or metabolic associated fatty liver disease (MAFLD), as it is now known, has gradually increased. NAFLD is a disease with a spectrum of stages ranging from simple fatty liver (steatosis) to a severe form of steatosis, nonalcoholic steatohepatitis (NASH), which could progress to irreversible liver injury (fibrosis) and organ failure, and in some cases hepatocellular carcinoma (HCC). Although a liver biopsy remains the gold standard for accurate detection of this condition, it is unsuitable for clinical screening due to a higher risk of death. There is thus an increased need to find alternative techniques or tools for accurate diagnosis. Early detection for NASH matters for patients because NASH is the marker for severe disease progression. This review summarizes the current noninvasive tools for NAFLD diagnosis and their performance. We also discussed potential and newer alternative tools for diagnosing NAFLD.

Long non-coding RNAs in metabolic disorders: pathogenetic relevance and potential biomarkers and therapeutic targets

BACKGROUND

It has been suggested that dysregulation of long non-coding RNAs (lncRNAs) could be associated with the incidence and development of metabolic disorders.

AIM

Accordingly, this narrative review described the molecular mechanisms of lncRNAs in the development of metabolic diseases including insulin resistance, diabetes, obesity, non-alcoholic fatty liver disease (NAFLD), cirrhosis, and coronary artery diseases (CAD). Furthermore, we investigated the up-to-date findings on the association of deregulated lncRNAs in the metabolic disorders, and potential use of lncRNAs as biomarkers and therapeutic targets.

CONCLUSION

LncRNAs/miRNA/regulatory proteins axis plays a crucial role in progression of metabolic disorders and may be used in development of therapeutic and diagnostic approaches.

Non-alcoholic Steatohepatitis Pathogenesis, Diagnosis, and Treatment

There has been a rise in the prevalence of non-alcohol fatty liver disease (NAFLD) due to the popularity of western diets and sedentary lifestyles. One quarter of NAFLD patients is diagnosed with non-alcoholic steatohepatitis (NASH), with histological evidence not only of fat accumulation in hepatocytes but also of liver cell injury and death due to long-term inflammation. Severe NASH patients have increased risks of cirrhosis and liver cancer. In this review, we discuss the pathogenesis and current methods of diagnosis for NASH, and current status of drug development for this life-threatening liver disease.

Long non-coding RNA AC012668 suppresses non-alcoholic fatty liver disease by competing for microRNA miR-380-5p with lipoprotein-related protein LRP2

Nonalcoholic fatty liver disease (NAFLD) is characterized by high morbidity. Although long noncoding RNAs (lncRNAs) are known to have a role in NAFLD pathogenesis, the identified lncRNA types are limited. In this study, NAFLD models were established in vitro and in vivo using free fatty acid-treated LO2 cells and high-fat diet-fed mice, respectively. Microarray data were downloaded from the Gene Expression Omnibus database, and AC012668 was selected for further analysis. Cell viability and apoptosis were measured using Cell Counting Kit 8 and flow cytometry assays. RNA expression was detected using reverse transcription-quantitative polymerase chain reaction. Triglyceride (TG) content and lipid deposition were detected using enzyme-linked immunosorbent assay and Oil-Red O staining. Western blotting was used to visualize protein expression. Starbase and TargetScan were used to predict the target miRNA and gene, and the predictions were verified through RNA pull-down and luciferase reporter assays. AC012668 expression levels were significantly suppressed in NAFLD models, whereas AC012668 overexpression inhibited lipogenesis-related gene (SCD1, SREBP1, FAS) expression and TG/lipid accumulation in vitro. Subsequently, miR-380-5p was predicted and verified to target AC012668, and its expression was notably increased in the NAFLD cell model. Moreover, transfection of miR-380-5p antagonized the effects of AC012668 on lipid formation and accumulation. LRP2 was confirmed to be the target gene of miR-380-5p and was downregulated in the NAFLD cell model. Silencing LRP2 reversed the effects of the miR-380-5p inhibitor on lipid formation and accumulation. AC012668 inhibited NAFLD progression via the miR-380-5p/LRP2 axis. These findings may provide a novel strategy against NAFLD.

Circ_0057558 promotes nonalcoholic fatty liver disease by regulating ROCK1/AMPK signaling through targeting miR-206

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver disorders that is featured by the extensive deposition of fat in the hepatocytes. Current treatments are very limited due to its unclear pathogenesis. Here, we investigated the function of circ_0057558 and miR-206 in NAFLD. High-fat diet (HFD) feeding mouse was used as an in vivo NAFLD model and long-chain-free fatty acid (FFA)-treated liver cells were used as an in vitro NAFLD model. qRT-PCR was used to measure levels of miR-206, ROCK1 mRNA, and circ_0057558, while Western blotting was employed to determine protein levels of ROCK1, p-AMPK, AMPK, and lipogenesis-related proteins. Immunohistochemistry were performed to examine ROCK1 level. Oil-Red O staining was used to assess the lipid deposition in cells. ELISA was performed to examine secreted triglyceride (TG) level. Dual-luciferase assay was used to validate interactions of miR-206/ROCK1 and circ_0057558/miR-206. RNA immunoprecipitation was employed to confirm the binding of circ_0057558 with miR-206. Circ_0057558 was elevated while miR-206 was reduced in both in vivo and in vitro NAFLD models. miR-206 directly bound with ROCK1 3'-UTR and suppressed lipogenesis and TG secretion through targeting ROCK1/AMPK signaling. Circ_0057558 directly interacted with miR-206 to disinhibit ROCK1/AMPK signaling. Knockdown of circ_0057558 or overexpression of miR-206 inhibited lipogenesis, TG secretion and expression of lipogenesis-related proteins. ROCK1 knockdown reversed the effects of circ_0057558 overexpression. Injection of miR-206 mimics significantly ameliorated NAFLD progression in vivo. Circ_0057558 acts as a miR-206 sponge to de-repress the ROCK1/AMPK signaling and facilitates lipogenesis and TG secretion, which greatly contributes to NAFLD development and progression.

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.

Potential Therapeutic Targeting of lncRNAs in Cholesterol Homeostasis

Maintaining cholesterol homeostasis is essential for normal cellular and systemic functions. Long non-coding RNAs (lncRNAs) represent a mechanism to fine-tune numerous biological processes by controlling gene expression. LncRNAs have emerged as important regulators in cholesterol homeostasis. Dysregulation of lncRNAs expression is associated with lipid-related diseases, suggesting that manipulating the lncRNAs expression could be a promising therapeutic approach to ameliorate liver disease progression and cardiovascular disease (CVD). However, given the high-abundant lncRNAs and the poor genetic conservation between species, much work is required to elucidate the specific role of lncRNAs in regulating cholesterol homeostasis. In this review, we highlighted the latest advances in the pivotal role and mechanism of lncRNAs in regulating cholesterol homeostasis. These findings provide novel insights into the underlying mechanisms of lncRNAs in lipid-related diseases and may offer potential therapeutic targets for treating lipid-related diseases.

lncRNA MIR155HG Accelerates the Progression of Sepsis via Upregulating MEF2A by Sponging miR-194-5p

Long noncoding RNA MIR155HG exerts important effects in the progression of multiple diseases. This study investigated the functions of MIR155HG in sepsis development. Blood samples were collected from 28 patients with sepsis and 28 without sepsis. The murine cardiac muscle cell line (HL-1) and macrophage cell line (RAW 264.7) treated with lipopolysaccharide (LPS) were used as the in vitro sepsis models. The levels of MIR155HG, miR-194-5p, and MEF2A were determined using real-time-quantitative polymerase chain reaction. Cell counting kit-8 and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assays were used to assess cell viability and apoptosis, respectively. The association between miR-194-5p and MIR155HG or MEF2A was confirmed using a dual-luciferase reporter assay. The levels of inflammatory cytokines were detected using enzyme-linked immunosorbent assay (ELISA). In this study, we demonstrated that MIR155HG expression was significantly increased in sepsis blood samples, RAW 264.7, and HL-1 cells treated with LPS. Silencing of MIR155HG promoted cell viability and obstructed cell apoptosis and inflammation of RAW 264.7 and HL-1 cells treated with LPS. MiR-194-5p depletion abrogated cell viability promotion and suppressive effect on cell apoptosis and inflammation caused by MIR155HG knockdown. In addition, MIR155HG upregulated MEF2A through interaction with miR-194-5p. Finally, rescue assays indicated that MEF2A overexpression abolished the inhibitory effect on sepsis progression induced by MIR155HG deletion. In conclusion, MIR155HG promotes sepsis progression in an in vitro sepsis model by modulating the miR-194-5p/MEF2A axis. This discovery provides a promising biomarker for sepsis therapy.

The long and the small collide: LncRNAs and small heterodimer partner (SHP) in liver disease

Long non-coding RNAs (lncRNAs) are a large and diverse class of RNA molecules that are transcribed but not translated into proteins, with a length of more than 200 nucleotides. LncRNAs are involved in gene expression and regulation. The abnormal expression of lncRNAs is associated with disease pathogenesis. Small heterodimer partner (SHP, NR0B2) is a unique orphan nuclear receptor that plays a pivotal role in many biological processes by acting as a transcriptional repressor. In this review, we present the critical roles of SHP and summarize recent findings demonstrating the regulation between lncRNAs and SHP in liver disease.

MicroRNAs in the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), or, more accurately, metabolic associated fatty liver disease, accounts for a large proportion of chronic liver disorders worldwide and is closely associated with other conditions such as cardiovascular disease, obesity, and type 2 diabetes mellitus. NAFLD ranges from simple steatosis to nonalcoholic steatohepatitis (NASH) and can progress to cirrhosis and, eventually, also hepatocellular carcinoma. The morbidity and mortality associated with NAFLD are increasing rapidly year on year. Consequently, there is an urgent need to understand the etiology and pathogenesis of NAFLD and identify effective therapeutic targets. MicroRNAs (miRNAs), important epigenetic factors, have recently been proposed to participate in NAFLD pathogenesis. Here, we review the roles of miRNAs in lipid metabolism, inflammation, apoptosis, fibrosis, hepatic stellate cell activation, insulin resistance, and oxidative stress, key factors that contribute to the occurrence and progression of NAFLD. Additionally, we summarize the role of miRNA-enriched extracellular vesicles in NAFLD. These miRNAs may comprise suitable therapeutic targets for the treatment of this condition.

The role of long noncoding RNAs in livestock adipose tissue deposition - A review

With the development of sequencing technology, numerous, long noncoding RNAs (lncRNAs) have been discovered and annotated. Increasing evidence has shown that lncRNAs play an essential role in regulating many biological and pathological processes, especially in cancer. However, there have been few studies on the roles of lncRNAs in livestock production. In animal products, meat quality and lean percentage are vital economic traits closely related to adipose tissue deposition. However, adipose tissue accumulation is also a pivotal contributor to obesity, diabetes, atherosclerosis, and many other diseases, as demonstrated by human studies. In livestock production, the mechanism by which lncRNAs regulate adipose tissue deposition is still unclear. In addition, the phenomenon that different animal species have different adipose tissue accumulation abilities is not well understood. In this review, we summarize the characteristics of lncRNAs and their four functional archetypes and review the current knowledge about lncRNA functions in adipose tissue deposition in livestock species. This review could provide theoretical significance to explore the functional mechanisms of lncRNAs in adipose tissue accumulation in animals.

Elevation of plasma tRNA fragments as a promising biomarker for liver fibrosis in nonalcoholic fatty liver disease

Fibrotic tissue remodelling in nonalcoholic fatty liver disease (NAFLD) will probably emerge as the leading cause of end-stage liver disease in the coming decades, but the ability to diagnose liver fibrosis in NAFLD patients noninvasively is limited. The abnormal expression of tRNA-derived small RNA (tsRNA) in plasma provides a novel idea for noninvasive diagnosis of various diseases, however, the relationship between tsRNAs and NAFLD is still unknown. Here, we took advantage of small RNA-Seq technology to profile tsRNAs in NAFLD patients and found the ubiquitous presence of hepatic tsRNAs secreted into circulating blood. Verification in a cohort of 114 patients with NAFLD and 42 patients without NAFLD revealed that three tsRNAs (tRF-Val-CAC-005, tiRNA-His-GTG-001, and tRF-Ala-CGC-006) were significantly elevated in the plasma of NAFLD patients, and the expression level are associated with NAFLD activity score (calculated from 0 to 8) and fibrosis stage (scored from 0 to 4). In mouse models, we further found that increased plasma levels of these three tsRNAs were positively correlated with the degree of liver fibrosis. Our study potentially identifies a new class of NAFLD biomarkers and reveal the possible existence of tsRNAs in the blood that can be used to predict fibrogenesis risk in patients diagnosed with NAFLD.

LncRNA-Gm9795 promotes inflammation in non-alcoholic steatohepatitis via NF-[Formula: see text]B/JNK pathway by endoplasmic reticulum stress

BACKGROUND

Non-alcoholic steatohepatitis (NASH) is a key stage in leading development of non-alcoholic simple fatty liver (NAFL) into cirrhosis and even liver cancer. This study aimed at exploring the lncRNAs expression profile in NASH and the biological function of a novel LncRNA-gm9795.

METHODS

Microarray analysis was performed to compare the expression profiles of lncRNAs in the liver of NASH, NAFLD and normal mice (5 mice for each group). Methionine-choline-deficient Medium (MCD) with Lipopolysaccharide (LPS) or palmitic acid (PA)were used to built NASH cell models. The role and mechanism of LncRNA-gm9795 in NASH were explored by knocking down or over-expressing its expression.

RESULTS

A total of 381 lncRNAs were found to be not only highly expressed in NAFLD, but also is going to go even higher in NASH. A novel LncRNA-gm9795 was significantly highly expressed in liver tissues of NASH animal models and NASH cell models. By staining with Nile red, we found that gm9795 did not affect the fat accumulation of NASH. However, gm9795 in NASH cell models significantly promoted the expression of TNF [Formula: see text], IL-6, IL-1[Formula: see text], the important inflammatory mediators in NASH. At the same time, we found that gm9795 upregulated the key molecules in endoplasmic reticulum stress (ERS), while NF-[Formula: see text]B/JNK pathways were also activated. When ERS activator Thapsigargin (TG) was introduced in cells with Ggm9757 si-RNA, NF-[Formula: see text]B and JNK pathways were activated. Conversely, ERS inhibitor Tauroursodeoxycholic acid (TUDCA) inhibited NF-kB and JNK pathways in cells with gm9795 overexpression plasmid.

CONCLUSION

LncRNA-gm9795 promotes inflammatory response in NASH through NF-kB and JNK pathways by ERS, which might provide theoretical basis for revealing the pathogenesis of NASH and discovering new therapeutic targets.

Silencing of MEG3 attenuated the role of lipopolysaccharides by modulating the miR-93-5p/PTEN pathway in Leydig cells

BACKGROUND

Leydig cells reflect the activation of inflammation, decrease of androgen production, inhibition of cell growth and promotion of cell apoptosis under orchitis. Maternally expressed gene 3 (MEG3) exerts a crucial role in various human diseases, but under orchitis, the role and underlying molecular mechanism of MEG3 in Leydig cells remain unclear.

METHODS

Lipofectamine 2000 was used for the cell transfections. qPCR and western blots assay were applied to assess the gene expression. ELISA assay was used to measure the TNFα, IL6 and testosterone secretion. CCK8 and EdU assay was employ to test the cell viability and proliferation respectively. Luciferase reporter and RIP assay were introduced to detect the binding of miR-93-5p with MEG3 and PTEN.

RESULTS

Lipopolysaccharides (LPS) induced TNFα and IL6 secretion, lowered testosterone production, inhibited cell viability and proliferation, and induced cell apoptosis in Leydig cells. MEG3 was upregulated in Leydig cells treated with LPS and that knockdown of MEG3 inhibited the role of LPS in Leydig cells. MEG3 absorbed miR-93-5p and that suppression of miR-93-5p restored the role of silenced MEG3 in Leydig cells under LPS treatment. miR-93-5p inhibited PTEN expression and that over-expressed PTEN alleviated the effect of miR-93-5p in Leydig cells treated with LPS. LPS activated the MEG3/miR-93-5p/PTEN signalling pathway in Leydig cells.

CONCLUSIONS

This study revealed that MEG3 serves as a molecular sponge to absorb miR-93-5p, thus leading to elevation of PTEN expression in Leydig cells under LPS treatment, offering a theoretical basis on which to establish potential new treatment strategies for orchitis.

A comprehensive review of long non-coding RNAs in the pathogenesis and development of non-alcoholic fatty liver disease

One of the most prevalent diseases worldwide without a fully-known mechanism is non-alcoholic fatty liver disease (NAFLD). Recently, long non-coding RNAs (lncRNAs) have emerged as significant regulatory molecules. These RNAs have been claimed by bioinformatic research that is involved in biologic processes, including cell cycle, transcription factor regulation, fatty acids metabolism, and-so-forth. There is a body of evidence that lncRNAs have a pivotal role in triglyceride, cholesterol, and lipoprotein metabolism. Moreover, lncRNAs by up- or down-regulation of the downstream molecules in fatty acid metabolism may determine the fatty acid deposition in the liver. Therefore, lncRNAs have attracted considerable interest in NAFLD pathology and research. In this review, we provide all of the lncRNAs and their possible mechanisms which have been introduced up to now. It is hoped that this study would provide deep insight into the role of lncRNAs in NAFLD to recognize the better molecular targets for therapy.

The gene expression of long non-coding RNAs (lncRNAs): MEG3 and H19 in adipose tissues from obese women and its association with insulin resistance and obesity indices

Background

There is evidence regarding the role of two lncRNAs: MEG3 and H19 the pathomechanism of obesity and related disorders. Here, we aimed to evaluate the expression of MEG3 and H19 in visceral adipose tissues (VAT) and subcutaneous adipose tissues (SAT) of obese women (n = 18), as compared to normal‐weight women (n = 17). Moreover, we sought to identify the association of expression of MEG3 and H19 in SAT and VAT with obesity parameters, insulin resistance, and the mRNA expression of possible target genes involved in adipogenesis and lipogenesis including peroxisome proliferator‐activated receptor gamma (PPARγ), fatty acid synthase (FAS), and acetyl‐CoA carboxylase (ACC).

Methods

Real‐time PCR was performed to investigate the mRNA expression of the above‐mentioned genes in VAT and SAT from all participants.

Results

The results showed lower mRNA levels of H19 in SAT of obese women, compared to normal‐weight women, while MEG3 expression was significantly higher in the SAT of the obese group rather than controls. Correlation analysis indicated that the transcript level of H19 had an inverse correlation with obesity indices and HOMA‐IR values. However, MEG3 expression displayed a positive correlation with all the indicated parameters in all participants. Interestingly, a positive correlation was found between transcript level of MEG3 in SAT with FAS and PPARγ. However, there was an inverse correlation between SAT expression of H19 and FAS.

Conclusions

It appears that lncRNAs, MEG3 and H19, are involved in obesity‐related conditions. However, more clinical studies are still required to clarify the relationships between lncRNAs with obesity and related abnormalities.

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.

Upregulated lncRNA HCG18 in Patients with Non-Alcoholic Fatty Liver Disease and Its Regulatory Effect on Insulin Resistance

PURPOSE

Non-alcoholic fatty liver disease (NAFLD) is a disease associated with genetic-environmental-metabolic stress, which severely damages the liver function of patients. This study aimed to explore the significance and probable functions of HCG18 in NAFLD.

PATIENTS AND METHODS

The expression of HCG18 and miR-197-3p was tested by qRT-PCR. The clinical signification of HCG18 was provided by the ROC curve and Pearson correlation. The corresponding mechanism was punctuated by the luciferase reporter assay and HFD-managed mice.

RESULTS

HCG18 expression was higher in the patients with NAFLD than in controls and in individuals with HOMA-IR score ≥2.5 than those with HOMA-IR score <2.5. HCG18 expression in NAFLD patients was related to BMI, HOMA-IR, ALT, FBG, TC, and TG. HCG18 showed satisfactory predictive accuracy in differentiating NAFLD patients and patients with HOMA-IR ≥2.5. Besides, HCG18 had protective impacts on blood glucose and fat deposition but not on body weight. MiR-197-3p is a direct gene of HCG18, and a reverse correlation was found between miR-197-3p and HCG18. Furthermore, miR-197-3p regulated the influence of HCG18 on insulin resistance and lipid accumulation.

CONCLUSION

Increased levels of HCG18 might be an alternate indicator for NAFLD patients. The HCG18-miR-197-3p axis exerted effects on the progression of fat sedimentation and glucose disorder in NAFLD.

BTEB2-Activated lncRNA TSPEAR-AS2 Drives GC Progression through Suppressing GJA1 Expression and Upregulating CLDN4 Expression

Long non-coding RNAs (lncRNAs) are characterized as key layers of the genome in various cancers. TSPEAR-AS2 was highlighted to be a candidate lncRNA potentially involved in gastric cancer (GC) progression. However, the clinical significance and mechanism of TSPEAR-AS2 in GC required clarification. The clinical significance of TSPEAR-AS2 was elucidated through Kaplan-Meier Plotter. The mechanism of TSPEAR-AS2 in GC was clarified in vitro and in vivo using luciferase reporter, chromatin immunoprecipitation, RNA immunoprecipitation assays, and animal models. TSPEAR-AS2 elevation was closely correlated with overall survival of GC patients. A basic transcription element-binding protein 2 (BTEB2)-activated TSPEAR-AS2 model was first explored in this study. TSPEAR-AS2 silencing substantially reduced tumorigenic capacities of GC cells, while TSPEAR-AS2 elevation had the opposite effect. Mechanistically, TSPEAR-AS2 bound with both polycomb repressive complex 2 (PRC2) and argonaute 2 (Ago2). TSPEAR-AS2 knockdown significantly decreased H3K27me3 levels at promoter regions of gap junction protein alpha 1 (GJA1). Ago2 was recruited by TSPEAR-AS2, which was defined to sponge miR-1207-5p, contributing to the repression of claudin 4 (CLDN4) translation. The axis of EZH2/GJA1 and miR-1207-5p/CLDN4 mediated by BTEB2-activated-TSPEAR-AS2 plays an important role in GC progression, suggesting a new therapeutic direction in GC treatment.

Long noncoding RNA MEG3 blocks telomerase activity in human liver cancer stem cells epigenetically

BACKGROUND

MEG3 downregulated the expression in several tumors and inhibits human tumorigenesis. But so far, the mechanism of MEG3 in tumorigenesis is still unclear.

METHODS

In gene infection, cellular and molecular technologies and tumorigenesis test in vitro and in vivo were performed, respectively.

RESULTS

Our results indicate that MEG3 enhances the P53 expression by triggering the loading of P300 and RNA polymerase II onto its promoter regions dependent on HP1α. Moreover, MEG3 increases the methylation modification of histone H3 at the 27th lysine via P53. Furthermore, MEG3 inhibits the expression of TERT by increasing the H3K27me3 in TERT promoter regions, thereby inhibiting the activity of telomerase by reducing the binding of TERT to TERC. Furthermore, MEG3 also increases the expression of TERRA; therefore, the interaction between TERC and TERT was competitively attenuated by increasing the interaction between TERRA and TERT, which inhibits the activity of telomerase in hLCSCs. Strikingly, MEG3 reduces the length of telomere by blocking the formation of complex maintaining telomere length (POT1-Exo1-TRF2-SNM1B) and decreasing the binding of the complex to telomere by increasing the interplay between P53 and HULC. Ultimately, MEG3 inhibits the growth of hLCSCs by reducing the activity of telomerase and attenuating telomeric repeat binding factor 2(TRF2).

CONCLUSIONS

Our results demonstrates MEG3 inhibits the occurrence of human liver cancer by blocking telomere, and these findings provide an important insight into the prevention and treatment of human liver cancer.

LncRNA NEAT1: Shedding light on mechanisms and opportunities in liver diseases

With advances in genome and transcriptome research technology, the function and mechanism of lncRNAs in physiological and pathological states have been gradually revealed. Nuclear Enriched Abundant Transcript 1 (NEAT1, a long non-coding RNA), a vital component of paraspeckles, plays an indispensable role in the formation and integrity of paraspeckles. Throughout the research history, NEAT1 is mostly aberrantly upregulated in various cancers, and high expression of NEAT1 often contributes to poor prognosis of patients. Notably, the role and mechanism of NEAT1 in liver diseases have been increasingly reported. NEAT1 accelerates the progression of non-alcoholic fatty liver disease (NAFLD), liver fibrosis and hepatocellular carcinoma, while exerting a protective role in the pathogenesis of acute-on-chronic liver failure by inhibiting the inflammatory response. In this review, we will elaborate on relevant studies on the different casting of NEAT1 in liver diseases, especially focusing on its regulatory mechanisms and new opportunities for alcoholic liver disease.

Evolutionary conservation of long non-coding RNAs in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of conditions ranging from hepatic steatosis to steatohepatitis (NASH) to fibrosis in the absence of alcohol consumption. Its pathogenesis involves both genetic and environmental factors with a multitude of underlying molecular mechanisms and mediators at each stage. Recent transcriptomic-based studies have led to the identification and association of long non-coding RNAs (lncRNAs) with disease pathology in NAFLD patients and in vivo rodent models. However, the knowledge of function of most of the lncRNAs in NAFLD pathology remains obscure. In the current review, we give a comprehensive catalogue of well reported lncRNAs in NAFLD and classify them using sequence and synteny-based evolutionary conservation across rodents, nonhuman primate and human species. The conserved lncRNAs across all the three species may be dissected in larger clinical studies of NAFLD and can be explored as biomarkers and therapeutic targets. In addition, we also review and analyse single nucleotide polymorphisms (SNPs) in these lncRNAs. It adds another facet to the regulatory role of NAFLD-associated lncRNAs and underscores the significance of a novel genetic landscape of non-coding genome in determining the genetic susceptibility of NAFLD.

Long Non-Coding RNAs in Liver Cancer and Nonalcoholic Steatohepatitis

This review aims to highlight the recent findings of long non-coding RNAs (lncRNAs) in liver disease. In particular, we focus on the functions of lncRNAs in hepatocellular carcinoma (HCC) and non-alcoholic steatohepatitis (NASH). We summarize the current research trend in lncRNAs and their potential as biomarkers and therapeutic targets for the treatment of HCC and NASH.

Long-Noncoding RNA FGD5-AS1 Enhances the Viability, Migration, and Invasion of Glioblastoma Cells by Regulating the miR-103a-3p/TPD52 Axis

Purpose

This study was designed to explore the functional role of FYVE, RhoGEF, and PH domain containing 5 antisense RNA 1 (FGD5-AS1) and the underlying regulatory mechanism in the progression of glioblastoma (GBM).

Materials and Methods

FGD5-AS1 expression was analyzed in The Cancer Genome Atlas (TCGA), and then detected in GBM tissues and cells by quantitative reverse-transcription polymerase chain reaction. Viability, migration, and invasion of GBM cells were assessed using the MTT, wound healing, and transwell assays, respectively. StarBase/TargetScan analysis and dual-luciferase reporter gene (DLR) assay were performed to investigate the relationship between FGD5-AS1/tumor protein D52 (TPD52) and miR-103a-3p. A xenograft tumor model was established to evaluate the role of FGD5-AS1 in GBM tumorigenesis in vivo.

Results

FGD5-AS1 was overexpressed in GBM tissues and cells, and silencing of FGD5-AS1 expression resulted in the inhibition of the viability, migration, and invasion of GBM cells. miR-130-3p was a target of FGD5-AS1, and its expression was negatively regulated by FGD5-AS1. Silencing miR-103a-3p expression resulted in the abrogation of the inhibitory effects of si-FGD5-AS1 on the viability, migration, and invasion of GBM cells. TPD52 was a target of miR-103a-3p and suppressed the antitumor effects of FGD5-AS1 silencing on GBM cells. In addition, FGD5-AS1 silencing inhibited the growth of xenograft tumors in vivo by modulating the miR-103a-3p/TPD52 axis.

Conclusion

Silencing of FGD5-AS1 inhibited the viability, migration, and invasion of GBM cells by regulating the miR-103a-3p/TPD52 axis.

The lncRNA Gm15622 stimulates SREBP-1c expression and hepatic lipid accumulation by sponging the miR-742-3p in mice

Excessive lipid deposition is a hallmark of NAFLD. Although much has been learned about the enzymes and metabolites involved in NAFLD, few studies have focused on the role of long noncoding RNAs (lncRNAs) in hepatic lipid accumulation. Here, using in vitro and in vivo models of NAFLD, we found that the lncRNA Gm15622 is highly expressed in the liver of obese mice fed a HFD and in murine liver (AML-12) cells treated with free fatty acids. Investigating the molecular mechanism in the liver-enriched expression of Gm15622 and its effects on lipid accumulation in hepatocytes and on NAFLD pathogenesis, we found that Gm15622 acts as a sponge for the microRNA miR-742-3p. This sponging activity increased the expression of the transcriptional regulator SREBP-1c and promoted lipid accumulation in the liver of the HFD mice and AML-12 cells. Moreover, further results indicated that metformin suppresses Gm15622 and alleviates NAFLD-associated lipid deposition in mice. In conclusion, we have identified an lncRNA Gm15622/miR-742-3p/SREBP-1c regulatory circuit associated with NAFLD in mice, a finding that significantly advances our insight into how lipid metabolism and accumulation are altered in this metabolic disorder. Our results also suggest that Gm15622 may be a potential therapeutic target for managing NAFLD.

Low-density lipoprotein receptor-related protein 6-mediated signaling pathways and associated cardiovascular diseases: diagnostic and therapeutic opportunities

Low-density lipoprotein receptor-related protein 6 (LRP6) is a member of the low-density lipoprotein receptors (LDLRs) family and accumulating evidence points to the critical role of LRP6 in cardiovascular health and homeostasis. In addition to presenting the well-appreciated roles in canonical signaling regulating blood pressure, blood glucose, lipid metabolism, atherosclerosis, cardiac valve disease, cardiac development, Alzheimer's disease and tumorigenesis, LRP6 also inhibits non-canonical Wnt signals that promote arterial smooth muscle cell proliferation and vascular calcification. Noticeably, the role of LRP6 is displayed in cardiometabolic disease, an increasingly important clinical burden with aging and obesity. The prospect for cardiovascular diseases treatment via targeting LRP6-mediated signaling pathways may improve central blood pressure and lipid metabolism, and reduce neointima formation and myocardial ischemia-reperfusion injury. Thus, a deep and comprehensive understanding of LRP6 structure, function and signaling pathways will contribute to clinical diagnosis, therapy and new drug development for LRP6-related cardiovascular diseases.