Targeting H19, an Imprinted Long Non-Coding RNA, in Hepatic Functions and Liver Diseases

Long non-coding RNAs in biomarking COVID-19: a machine learning-based approach

BACKGROUND

The coronavirus pandemic that started in 2019 has caused the highest mortality and morbidity rates worldwide. Data on the role of long non-coding RNAs (lncRNAs) in coronavirus disease 2019 (COVID-19) is scarce. We aimed to elucidate the relationship of three important lncRNAs in the inflammatory states, H19, taurine upregulated gene 1 (TUG1), and colorectal neoplasia differentially expressed (CRNDE) with key factors in inflammation and fibrosis induction including signal transducer and activator of transcription3 (STAT3), alpha smooth muscle actin (α-SMA), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) in COVID-19 patients with moderate to severe symptoms.

METHODS

Peripheral blood mononuclear cells from 28 COVID-19 patients and 17 healthy controls were collected. The real-time quantitative polymerase chain reaction (RT-qPCR) was performed to evaluate the expression of RNAs and lncRNAs. Western blotting analysis was also performed to determine the expression levels of STAT3 and α-SMA proteins. Machine learning and receiver operating characteristic (ROC) curve analysis were carried out to evaluate the distinguishing ability of lncRNAs.

RESULTS

The expression levels of H19, TUG1, and CRNDE were significantly overexpressed in COVID-19 patients compared to healthy controls. Moreover, STAT3 and α-SMA expression levels were remarkedly increased at both transcript and protein levels in patients with COVID-19 compared to healthy subjects and were correlated with Three lncRNAs. Likewise, IL-6 and TNF-α were considerably upregulated in COVID-19 patients. Machine learning and ROC curve analysis showed that CRNDE-H19 panel has the proper ability to distinguish COVID-19 patients from healthy individuals (area under the curve (AUC) = 0.86).

CONCLUSION

The overexpression of three lncRNAs in COVID-19 patients observed in this study may align with significant manifestations of COVID-19. Furthermore, their co-expression with STAT3 and α-SMA, two critical factors implicated in inflammation and fibrosis induction, underscores their potential involvement in exacerbating cardiovascular, pulmonary and common symptoms and complications associated with COVID-19. The combination of CRNDE and H19 lncRNAs seems to be an impressive host-based biomarker panel for screening and diagnosis of COVID-19 patients from healthy controls. Research into lncRNAs can provide a robust platform to find new viral infection-related mediators and propose novel therapeutic strategies for viral infections and immune disorders.

Long non-coding RNAs and pancreatic cancer: A multifaceted view

Pancreatic cancer (PC) is a highly malignant disease with a 5-year survival rate of only 10%. Families with PC are at greater risk, as are type 2 diabetes, pancreatitis, and other factors. Insufficient early detection methods make this cancer have a poor prognosis. Additionally, the molecular mechanisms underlying PC development remain unclear. Increasing evidence suggests that long non-coding RNAs (lncRNAs) contribute to PC pathology,which may control gene expression by recruiting histone modification complexes to chromatin and interacting with proteins and RNAs. In recent studies, abnormal regulation of lncRNAs has been implicated in PC proliferation, metastasis, invasion, angiogenesis, apoptosis, and chemotherapy resistance suggesting potential clinical implications. The paper reviews the progress of lncRNA research in PC about diabetes mellitus, pancreatitis, cancer metastasis, tumor microenvironment regulation, and chemoresistance. Furthermore, lncRNAs may serve as potential therapeutic targets and biomarkers for PC diagnosis and prognosis. This will help improve PC patients' survival rate from a lncRNA perspective.

Epigenetic Mechanisms Contribute to Intraindividual Variations of Drug Metabolism Mediated by Cytochrome P450 Enzymes

Significant interindividual and intraindividual variations on cytochrome P450 (CYP)-mediated drug metabolism exist in the general population globally. Genetic polymorphisms are one of the major contribution factors for interindividual variations, but epigenetic mechanisms mainly contribute to intraindividual variations, including DNA methylation, histone modifications, microRNAs, and long non-coding RNAs. The current review provides analysis of advanced knowledge in the last decade on contributions of epigenetic mechanisms to intraindividual variations on CYP-mediated drug metabolism in several situations, including (1) ontogeny, the developmental changes of CYP expression in individuals from neonates to adults; (2) increased activities of CYP enzymes induced by drug treatment; (3) increased activities of CYP enzymes in adult ages induced by drug treatment at neonate ages; and (4) decreased activities of CYP enzymes in individuals with drug-induced liver injury (DILI). Furthermore, current challenges, knowledge gaps, and future perspective of the epigenetic mechanisms in development of CYP pharmacoepigenetics are discussed. In conclusion, epigenetic mechanisms have been proven to contribute to intraindividual variations of drug metabolism mediated by CYP enzymes in age development, drug induction, and DILI conditions. The knowledge has helped understanding how intraindividual variation are generated. Future studies are needed to develop CYP-based pharmacoepigenetics to guide clinical applications for precision medicine with improved therapeutic efficacy and reduced risk of adverse drug reactions and toxicity. SIGNIFICANCE STATEMENT: Understanding epigenetic mechanisms in contribution to intraindividual variations of CYP-mediated drug metabolism may help to develop CYP-based pharmacoepigenetics for precision medicine to improve therapeutic efficacy and reduce adverse drug reactions and toxicity for drugs metabolized by CYP enzymes.

Recent advances in the role of exosomes in liver fibrosis

BACKGROUND AND AIM

We aim to summarize the current status of research on the role of exosomes in liver fibrosis.

METHODS

A review of the relevant literature was performed and the key findings were presented.

RESULTS

Most studies focused on the role of exosomes derived from mesenchymal stem cells, other types of stem cells, and liver resident cells including hepatocytes, cholangiocytes, and hepatic stellate cells in liver fibrosis. Exosomes have been reported to play an essential role in the inactivation or activation of hepatic stellate cells through the delivery of non-coding RNAs and proteins. In recent years, this exosome cargo has become a research hotspot.

CONCLUSIONS

Recent studies have indicated the potential therapeutic benefit of exosomes in liver fibrosis.

Evaluation of H19, Mest, Meg3, and Peg3 genes affecting growth and metabolism in umbilical cord blood cells of infants born to mothers with gestational diabetes and healthy mothers in Rafsanjan City, Iran

Hyperglycemia during the first trimester leads to an increased risk of innate malformations as well as death at times close to delivery dates. The methylated genes include those from paternal H19 and PEG3 and those from maternal MEST and MEG3 that are necessary for the growth and regulation of the human fetus and its placenta. The aim of this study was to evaluate and compare the expression of these genes in the cord blood of healthy infants born to mothers with gestational diabetes mellitus (GDM) and healthy mothers.This case-control study was conducted on the cord blood of 40 infants born to mothers with GDM and 35 infants born to healthy mothers. Mothers were identified by measuring oral glucose tolerance in the 24th-26th week of pregnancy. Cord blood was obtained post-delivery, and cord blood mononuclear cells were immediately extracted, using Ficoll solution. Then, RNA extraction and cDNA synthesis were performed, and gene expression of MEG3, PEG3, H19, and MEST was assessed through quantitative real-time PCR.Findings show that the expression levels of MEG3, PEG3, H19, and MEST genes were significantly decreased in mononuclear cord blood cells of infants born to mothers with GDM when compared to those of the healthy control group.These findings reveal that the reduction of imprinted genes in mothers with GDM is most likely due to changes in their methylation by an epigenetic process. Considering the importance of GDM due to its high prevalence and its side effects both for mother and fetus, recognizing their exact mechanisms is of high importance. This has to be studied more widely.

Effect of metformin on the long non-coding RNA expression levels in type 2 diabetes: an in vitro and clinical trial study

BACKGROUND

It has been suggested that the anti-hyperglycemic effect of metformin could be associated with its impact on long non-coding RNA (lncRNA) expression levels. Accordingly, in the current study, we evaluated the effect of metformin on the expression of H19, MEG3, MALAT1, and GAS5 in in vitro and in vivo situations.

METHODS

The effect of hyperglycemia and metformin treatment on the lncRNAs expression level was evaluated in HepG2 cells. A total of 179 age- and sex-matched subjects, including 88 newly diagnosed patients with type 2 diabetes (T2D) and 91 healthy volunteers, were included in the case-control phase of the study. Moreover, 40 newly diagnosed patients participated in the study's open-labeled non-controlled clinical trial phase. The expression levels of lncRNA in HepG2 cells and whole blood samples were determined using QRT-PCR.

RESULTS

In vitro results showed that hyperglycemia induced H19 and MALAT1 and decreased GAS5 expression levels. Moreover, metformin decreased H19 and increased GAS5 expression in high glucose-treated cells. Case-control study findings revealed that the circulating levels of H19, MALAT1, and MEG3 were significantly elevated in T2D patients compared to the control subjects. Finally, results showed that the level of circulating H19 levels decreased while GAS5 increased in T2D patients after taking metformin for 2 months.

CONCLUSION

The results of the current study provided evidence that metformin could exert its effect in the treatment of T2D by altering the expression levels of H19 and GAS5.

The imprinted gene Zac1 regulates steatosis in developmental cadmium-induced nonalcoholic fatty liver disease

Cadmium (Cd) exposure in adulthood is associated with nonalcoholic fatty liver disease (NAFLD), characterized by steatosis, inflammation, and fibrosis. The prevalence of NAFLD in children is increasing, suggesting a role for the developmental environment in programming susceptibility. However, the role of developmental Cd exposure in programming NAFLD and the underlying mechanisms remain unclear. We have proposed that imprinted genes are strong candidates for connecting the early life environment and later life disease. In support of this, we previously identified roles for the Imprinted Gene Network (IGN) and its regulator Zac1 in programming NAFLD in response to maternal metabolic dysfunction. Here, we test the hypothesis that developmental Cd exposure is sufficient to program NAFLD, and further, that this process is mediated by Zac1 and the IGN. Using mice, we show that developmental cadmium chloride (CdCl2) exposure leads to histological, biochemical, and molecular signatures of steatosis and fibrosis in juveniles. Transcriptomic analyses comparing livers of CdCl2-exposed and control mice show upregulation of Zac1 and the IGN coincident with disease presentation. Increased hepatic Zac1 expression is independent of promoter methylation and imprinting statuses. Finally, we show that over-expression of Zac1 in cultured hepatocytes is sufficient to induce lipid accumulation in a Pparγ-dependent manner and demonstrate direct binding of Zac1 to the Pparγ promoter. Our findings demonstrate that developmental Cd exposure is sufficient to program NAFLD in later life, and with our previous work, establish Zac1 and the IGN as key regulators of prosteatotic and profibrotic pathways, two of the major pathological hallmarks of NAFLD.

Long Noncoding RNAs in the Pathogenesis of Insulin Resistance

Insulin resistance (IR), designated as the blunted response of insulin target tissues to physiological level of insulin, plays crucial roles in the development and progression of diabetes, nonalcoholic fatty liver disease (NAFLD) and other diseases. So far, the distinct mechanism(s) of IR still needs further exploration. Long non-coding RNA (lncRNA) is a class of non-protein coding RNA molecules with a length greater than 200 nucleotides. LncRNAs are widely involved in many biological processes including cell differentiation, proliferation, apoptosis and metabolism. More recently, there has been increasing evidence that lncRNAs participated in the pathogenesis of IR, and the dysregulated lncRNA profile played important roles in the pathogenesis of metabolic diseases including obesity, diabetes and NAFLD. For example, the lncRNAs MEG3, H19, MALAT1, GAS5, lncSHGL and several other lncRNAs have been shown to regulate insulin signaling and glucose/lipid metabolism in various tissues. In this review, we briefly introduced the general features of lncRNA and the methods for lncRNA research, and then summarized and discussed the recent advances on the roles and mechanisms of lncRNAs in IR, particularly focused on liver, skeletal muscle and adipose tissues.

Intrachromosomal Looping and Histone K27 Methylation Coordinately Regulates the lncRNA H19-Fetal Mitogen IGF2 Imprinting Cluster in the Decidual Microenvironment of Early Pregnancy

Recurrent spontaneous abortion (RSA) is a highly heterogeneous complication of pregnancy with the underlying mechanisms remaining uncharacterized. Dysregulated decidualization is a critical contributor to the phenotypic alterations related to pregnancy complications. To understand the molecular factors underlying RSA, we explored the role of longnoncoding RNAs (lncRNAs) in the decidual microenvironment where the crosstalk at the fetal–maternal interface occurs. By exploring RNA-seq data from RSA patients, we identified H19, a noncoding RNA that exhibits maternal monoallelic expression, as one of the most upregulated lncRNAs associated with RSA. The paternally expressed fetal mitogen IGF2, which is reciprocally coregulated with H19 within the same imprinting cluster, was also upregulated. Notably, both genes underwent loss of imprinting, as H19 and IGF2 were actively transcribed from both parental alleles in some decidual tissues. This loss of imprinting in decidual tissues was associated with the loss of the H3K27m3 repressive histone marker in the IGF2 promoter, CpG hypomethylation at the central CTCF binding site in the imprinting control center (ICR), and the loss of CTCF-mediated intrachromosomal looping. These data suggest that dysregulation of the H19/IGF2 imprinting pathway may be an important epigenetic factor in the decidual microenvironment related to poor decidualization.

The multifaceted actions of the lncRNA H19 in cardiovascular biology and diseases

Cardiovascular diseases are the leading cause of death and debility worldwide. Various molecular mechanisms have been studied to better understand the development and progression of cardiovascular pathologies with hope to eradicate these diseases. With the advancement of the sequencing technology, it is revealed that the majority of our genome is non-coding. A growing body of literature demonstrates the critical role of long non-coding RNAs (lncRNAs) as epigenetic regulators of gene expression. LncRNAs can regulate cellular biological processes through various distinct molecular mechanisms. The abundance of lncRNAs in the cardiovascular system indicates their significance in cardiovascular physiology and pathology. LncRNA H19, in particular, is a highly evolutionarily conserved lncRNA that is enriched in cardiac and vascular tissue, underlining its importance in maintaining homeostasis of the cardiovascular system. In this review, we discuss the versatile function of H19 in various types of cardiovascular diseases. We highlight the current literature on H19 in the cardiovascular system and demonstrate how dysregulation of H19 induces the development of cardiovascular pathophysiology.

Long non-coding RNA H19 as a biomarker for hepatocellular carcinoma

BACKGROUND AND AIMS

Liver cancer stem cells (CSCs) could be involved in the carcinogenesis, recurrence, metastasis and chemoresistance of hepatocellular carcinoma (HCC). The aim of this study was to explore the role of lncRNA-H19 as a biomarker for liver cancer.

METHODS

LncRNA-H19 expression levels and the functional assays were conducted in EpCAM⁺ CD133⁺ CSCs and C57BL/6J mice fed with a high-fat high-cholesterol carbohydrate (HFHCC) or standard diet for 52 weeks. Liver tissue and plasma samples from patients with cirrhosis, with or without HCC, were used for the analyses of gene expression and circulating lncRNA-H19 levels in an estimation and validation cohort.

RESULTS

EpCAM⁺ CD133⁺ cells showed a stem cell-like phenotype, self-renewal capacity, upregulation of pluripotent gene expression and overexpressed lncRNA-H19 (p < .001). Suppression of lncRNA-H19 by antisense oligonucleotide treatment significantly reduced the self-renewal capacity (p < .001). EpCAM, CD133 and lncRNA-h19 expression increased accordingly with disease progression in HFHCC-fed mice (p < .05) and also in liver tissue from HCC patients (p = .0082). Circulating lncRNA-H19 levels were significantly increased in HCC patients in both cohorts (p = .013; p < .0001). In addition, lncRNA-H19 levels increased accordingly with BCLC staging (p < .0001) and decreased after a partial and complete therapeutic response (p < .05). In addition, patients with cirrhosis who developed HCC during follow-up showed higher lncRNA-H19 levels (p = .0025).

CONCLUSION

LncRNA-H19 expression was increased in CSCs, in liver tissue and plasma of patients with HCC and decreased after partial/complete therapeutic response. Those patients who developed HCC during the follow-up showed higher levels of lncRNA-H19. LncRNA-H19 could constitute a new biomarker of HCC.

Differential gene expression profile of multinodular goiter

Introduction

The goiter, a neglected heterogeneous molecular disease, remains a major indication for thyroidectomies in its endemic regions.

Objectives

This study analyzed differential gene expression in surgical specimens diagnosed with multi nodular and compared the data to that of thyroid tissue without multinodular goiter from patients undergoing thyroidectomy in Manaus-AM, Brazil using RNA-seq technology.

Methodology

The transcriptome information of the surgical specimen fragments with and without multinodular goiter was accessed by Illumina HiSeq 2000 New Generation Sequencing (NGS) using the RNA-seq NEBNext^® Ultra^™ RNA Library Prep Kit for Illumina^®—#E7530L protocol and differential gene expression analysis.

Results

Differences were found between the gene expression profiles of the diseased tissues and those of the healthy control tissues; at least 70 genes were differentially expressed. The HOTS gene was expressed only in multinodular goiter tissues (p < 0.05).

Conclusion

These results demonstrate that the gene expression profile of multinodular goiter is pro-tumoral and that HOTS can play a central role in multinodular goiter development.

Altered gene expression of VEGF, IGFs and H19 lncRNA and epigenetic profile of H19-DMR region in endometrial tissues of women with endometriosis

Background

Endometriosis, as chronic estrogen-dependent disease, is defined by the presence of endometrial-like tissue outside the uterus. Proliferation of endometrial tissue and neoangiogenesis are critical factors in development of endometriosis. Hence, vascular endothelial growth factor (VEGF) as well as insulin‐like growth factor 1 and 2 (IGF1, 2) may be involved as inducers of cellular proliferation or neoangiogenesis. Imprinted long noncoding RNA H19 (lncRNA H19) has been suggested to be involved in pathogenesis of endometriosis via regulation of cellular proliferation and differentiation. Epigenetic aberrations appear to play an important role in its pathogenesis. The present study was designed to elucidate VEGF, IGF1, IGF2 and H19 lncRNA genes expression and epigenetic alterations of differentially methylated region (DMR) of H19 (H19-DMR) regulatory region in endometrial tissues of patients with endometriosis, in comparison with control women.

Methods

In this case–control study, 24 women with and without endometriosis were studied for the relative expression of VEGF, IGF1, IGF2 and H19 lncRNA genes using real-time polymerase chain reaction (PCR) technique. Occupancy of the MeCP2 on DMR region of H19 gene was assessed using chromatin immunoprecipitation (ChIP), followed by real-time PCR.

Results

Genes expression profile of H19, IGF1 and IGF2 was decreased in eutopic and ectopic endometrial tissues of endometriosis group, compared to the control tissues. Decreased expression of H19 in ectopic samples was significant in comparison with the controls (P < 0.05). Gene expression of VEGF was increased in eutopic tissues of endometriosis group, compared to control group. Whereas its expression level was lower in ectopic lesions versus eutopic and control endometrial samples. ChIP analysis revealed significant and nearly significant hypomethylation of H19-DMR region II in eutopic and ectopic samples, compared to the control group respectively. This epigenetic change was aligned with expression of IGF2. While methylation of H19-DMR region I was not significantly different between the eutopic, ectopic and control endometrial samples.

Conclusion

These data showed that VEGF, IGF1, IGF2 and H19 lncRNA genes expression and epigenetic alterations of H19 lncRNA have dynamic role in the pathogenesis of endometriosis, specifically in the way that hypomethylation of H19-DMR region II can be involved in IGF2 dysregulation in endometriosis.

Long Noncoding RNA H19: A Novel Therapeutic Target Emerging in Oncology Via Regulating Oncogenic Signaling Pathways

Long noncoding RNA H19 (H19) is an imprinting gene with only maternal expression that is involved in regulating different processes in various types of cells. Previous studies have shown that abnormal H19 expression is involved in many pathological processes, such as cancer, mainly through sponging miRNAs, interacting with proteins, or regulating epigenetic modifications. Accumulating evidence has shown that several oncogenic signaling pathways lead to carcinogenesis. Recently, the regulatory relationship between H19 and oncogenic signaling pathways in various types of cancer has been of great interest to many researchers. In this review, we discussed the key roles of H19 in cancer development and progression via its regulatory function in several oncogenic signaling pathways, such as PI3K/Akt, canonical Wnt/β-catenin, canonical NF-κB, MAPK, JAK/STAT and apoptosis. These oncogenic signaling pathways regulated by H19 are involved in cell proliferation, proliferation, migration and invasion, angiogenesis, and apoptosis of various cancer cells. This review suggests that H19 may be a novel therapeutic target for cancers treatment by regulating oncogenic signaling pathways.

Expression changes of serum LINC00941 and LINC00514 in HBV infection-related liver diseases and their potential application values

BACKGROUND

Long non-coding RNAs (LncRNAs) are considered as potential diagnostic markers for a variety of tumors. Here, we aimed to explore the changes of LINC00941 and LINC00514 expression in hepatitis B virus (HBV) infection-related liver disease and evaluate their application value in disease diagnosis.

METHODS

Serum levels of LINC00941 and LINC00514 were detected by qRT-PCR. Potential diagnostic values were evaluated by receiver operating characteristic curve (ROC) analysis.

RESULTS

Serum LINC00941 and LINC00514 levels were elevated in patients with chronic hepatitis B (CHB), liver cirrhosis (LC), and hepatocellular carcinoma (HCC) compared with controls. When distinguishing HCC from controls, serum LINC00941 and LINC00514 had diagnostic parameters of an AUC of 0.919 and 0.808, sensitivity of 85% and 90%, and specificity of 86.67% and 56.67%, which were higher than parameters for alpha fetal protein (AFP) (all p < 0.0001). When distinguishing HCC from LC, CHB, or LC from controls, the combined detection of LINC00941 or LINC00514 can significantly improve the accuracy of AFP test alone (all p < 0.05).

CONCLUSIONS

LINC00941 and LINC00514 were increased in the serum of HBV infection-associated liver diseases and might be independent markers for the detection of liver diseases.

The Gut-Liver Axis in Chronic Liver Disease: A Macrophage Perspective

Chronic liver disease (CLD) is a growing health concern which accounts for two million deaths per year. Obesity, alcohol overconsumption, and progressive cholestasis are commonly characterized by persistent low-grade inflammation and advancing fibrosis, which form the basis for development of end-stage liver disease complications, including hepatocellular carcinoma. CLD pathophysiology extends to the intestinal tract and is characterized by intestinal dysbiosis, bile acid dysregulation, and gut barrier disruption. In addition, macrophages are key players in CLD progression and intestinal barrier breakdown. Emerging studies are unveiling macrophage heterogeneity and driving factors of their plasticity in health and disease. To date, in-depth investigation of how gut-liver axis disruption impacts the hepatic and intestinal macrophage pool in CLD pathogenesis is scarce. In this review, we give an overview of the role of intestinal and hepatic macrophages in homeostasis and gut-liver axis disruption in progressive stages of CLD.

LINC00265 maintains hepatocyte proliferation during liver regeneration by targeting miRNA-28-5p

Long noncoding RNAs have been implicated in many biological processes, but their roles in liver regeneration still need to be illustrated. Therefore, we aimed to investigate the role of LINC00265 as a pivotal regulator of hepatocyte proliferation during liver regeneration. It was found that LINC00265 is significantly upregulated in rat liver tissues at various time points after 2/3 liver resection. LINC00265 knockdown inhibited hepatocyte proliferation, induced cell apoptosis and led to G2/M phase cell cycle arrestment. In rats subjected to surgery, LINC00265 knockdown decreased liver/body weight ratio, attenuated improvement from liver damage and reduced Ki67 and PCNA expression. Luciferase reporter assays confirmed that miR-28-5p was a direct target of LINC00265, and inhibition of miR-28-5p abolished the effect of LINC00265 knockdown. In summary, LINC00265 might maintain hepatocyte proliferation by targeting miR-28-5p during liver regeneration and should be considered as a promising therapeutic option for hepatocyte regeneration after liver resection.

A Novel Sox9/lncRNA H19 Axis Contributes to Hepatocyte Death and Liver Fibrosis

Sox9 has been previously characterized as a transcription factor responsible for the extracellular matrix production during liver fibrosis. However, the deregulation and functional role of hepatocyte Sox9 in the progression of liver fibrosis remains elusive. Here, we found a significant increase of Sox9 in the hepatocytes isolated from CCl4-induced fibrotic liver and showed that antisense oligoribonucleotides depletion of Sox9 was sufficient to attenuate CCl4-induced liver fibrosis. Notably, the increase of Sox9 in hepatocyte was associated with the upregulation of long noncoding RNA H19 in both in vitro and in vivo systems. Mechanistic studies revealed that Sox9 induced H19 by binding to a conserved promoter region of H19. In vitro, hepatocyte injury triggered the increase of Sox9/H19 axis, whereas silence of H19 greatly alleviated the H2O2-induced hepatocyte apoptosis, suggesting that H19 functions as a downstream effector of Sox9 signaling and is involved in hepatocyte apoptosis. In animal experiments, inhibition of H19 alleviated the activation of hepatic stellate cells and reduced the extent of liver fibrosis, whereas ectopic expression of H19 abolished the inhibitory effects of Sox9 depletion on liver fibrosis, suggesting that the profibrotic effect of hepatocyte Sox9 depends on H19. Finally, we investigated the clinical relevance of Sox9/H19 axis to liver fibrosis and identified the increase of Sox9/H19 axis in liver cirrhosis patients. In conclusion, our findings link Sox9/H19 axis to the intrinsic mechanisms of hepatocyte apoptosis and may represent a hitherto unknown paradigm in hepatocyte injury associated with the progression of liver fibrosis.

Paternal obesity impairs hepatic gluconeogenesis of offspring by altering Igf2/H19 DNA methylation

Over the past four decades, the global prevalence of obesity has increased rapidly in all age ranges. Emerging evidence suggests that paternal lifestyle and environmental exposure have a crucial role in the health of offspring. Therefore, the current study investigated the impact of paternal obesity on the metabolic profile of offspring in a male mouse model of obesity. Female offspring of obese fathers fed a high-fat diet (HFD) (60% kcal fat) showed hyperglycemia because of enhanced gluconeogenesis and elevated expression of phosphoenolpyruvate carboxykinase (PEPCK), which is a key enzyme involved in the regulation of gluconeogenesis. Methylation of the Igf2/H19 imprinting control region (ICR) was dysregulated in the liver of offspring, and the sperm, of HFD fathers, suggesting that epigenetic changes in germ cells contribute to this father-offspring transmission. In addition, we explored whether H19 might regulate hepatic gluconeogenesis. Our results showed that overexpression of H19 in Hepa1-6 cells enhanced the expression of PEPCK and gluconeogenesis by promoting nuclear retention of forkhead box O1 (FOXO1), which is involved in the transcriptional regulation of Pepck. Thus, the current study suggests that paternal exposure to HFD impairs the gluconeogenesis of offspring via altered Igf2/H19 DNA methylation.

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.

Long noncoding RNA H19 - a new player in the pathogenesis of liver diseases

The liver is a vital organ that controls glucose and lipid metabolism, hormone regulation, and bile secretion. Liver injury can occur from various insults such as viruses, metabolic diseases, and alcohol, which lead to acute and chronic liver diseases. Recent studies have demonstrated the implications of long noncoding RNAs (lncRNAs) in the pathogenesis of liver diseases. These newly discovered lncRNAs have various functions attributing to many cellular biological processes via distinct and diverse mechanisms. LncRNA H19, one of the first lncRNAs being identified, is highly expressed in fetal liver but not in adult normal liver. Its expression, however, is increased in liver diseases with various etiologies. In this review, we focused on the roles of H19 in the pathogenesis of liver diseases. This comprehensive review is aimed to provide useful perspectives and translational applications of H19 as a potential therapeutic target of liver diseases.

Ovulation Induction Changes Epigenetic Marks of Imprinting Genes in Mice Fetus Organs

Objective

Genomic imprinting is an epigenetic phenomenon that plays a critical role in normal development of embryo. Using exogenous hormones during assisted reproductive technology (ART) can change an organism hormonal profile and subsequently affect epigenetic events. Ovarian stimulation changes gene expression and epigenetic pattern of imprinted genes in the organs of mouse fetus.

Materials and Methods

For this experimental study, expression of three imprinted genes H19, Igf2 (Insulin-like growth factor 2) and Cdkn1c (Cyclin-dependent kinase inhibitor 1C), which have important roles in development of placenta and embryo, and the epigenetic profile of their regulatory region in some tissues of 19-days-old female fetuses, from female mice subjected to ovarian stimulation, were evaluated by quantitative reverse-transcription PCR (qRT-PCR) and Chromatin immunoprecipitation (ChIP) methods.

Results

H19 gene was significantly lower in heart (P<0.05), liver (P<0.05), lung (P<0.01), placenta (P<0.01) and ovary (P<0.01). It was significantly higher in kidney of ovarian stimulation group compared to control fetuses (P<0.05). Igf2 expression was significantly higher in brain (P<0.05) and kidney (P<0.05), while it was significantly lower in lung of experimental group fetuses in comparison with control fetuses (P<0.05). Cdkn1c expression was significantly higher in lung (P<0.05). It was significantly decreased in placenta of experimental group fetuses rather than the control fetuses (P<0.05). Histone modification data and DNA methylation data were in accordance to the gene expression profiles.

Conclusion

Results showed altered gene expressions in line with changes in epigenetic pattern of their promoters in the ovarian stimulation group, compared to normal cycle.

Role of long non‑coding RNAs and related epigenetic mechanisms in liver fibrosis (Review)

Liver fibrosis is one of the major liver pathologies affecting patients worldwide. It results from an improper tissue repair process following liver injury or inflammation. If left untreated, it ultimately leads to liver cirrhosis and liver failure. Long non‑coding RNAs (lncRNAs) have been implicated in a wide variety of diseases. They can regulate gene expression and modulate signaling. Some of the lncRNAs promote, while others inhibit liver fibrosis. Similarly, other epigenetic processes, such as methylation and acetylation regulate gene transcription and can modulate gene expression. Notably, there are several regulatory associations of lncRNAs with other epigenetic processes. A major mechanism of action of long non‑coding RNAs is to competitively bind to their target microRNAs (miRNAs or miRs), which in turn affects miRNA availability and bioactivity. In the present review, the role of lncRNAs and related epigenetic processes contributing to liver fibrosis is discussed. Finally, various potential therapeutic approaches targeting lncRNAs and related epigenetic processes, which are being considered as possible future treatment targets for liver fibrosis are identified.

Regulation of Fetal Genes by Transitions among RNA-Binding Proteins during Liver Development

Transcripts of alpha-fetoprotein (Afp), H19, and insulin-like growth factor 2 (Igf2) genes are highly expressed in mouse fetal liver, but decrease drastically during maturation. While transcriptional regulation of these genes has been well studied, the post-transcriptional regulation of their developmental decrease is poorly understood. Here, we show that shortening of poly(A) tails and subsequent RNA decay are largely responsible for the postnatal decrease of Afp, H19, and Igf2 transcripts in mouse liver. IGF2 mRNA binding protein 1 (IMP1), which regulates stability and translation efficiency of target mRNAs, binds to these fetal liver transcripts. When IMP1 is exogenously expressed in mouse adult liver, fetal liver transcripts show higher expression and possess longer poly(A) tails, suggesting that IMP1 stabilizes them. IMP1 declines concomitantly with fetal liver transcripts as liver matures. Instead, RNA-binding proteins (RBPs) that promote RNA decay, such as cold shock domain containing protein E1 (CSDE1), K-homology domain splicing regulatory protein (KSRP), and CUG-BP1 and ETR3-like factors 1 (CELF1), bind to 3' regions of fetal liver transcripts. These data suggest that transitions among RBPs associated with fetal liver transcripts shift regulation from stabilization to decay, leading to a postnatal decrease in those fetal transcripts.

The Good, the Bad, the Question-H19 in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), the most common primary liver cancer, is challenging to treat due to its typical late diagnosis, mostly at an advanced stage. Therefore, there is a particular need for research in diagnostic and prognostic biomarkers and therapeutic targets for HCC. The use of long noncoding (lnc) RNAs can widen the list of novel molecular targets improving cancer therapy. In hepatocarcinogenesis, the role of the lncRNA H19, which has been known for more than 30 years now, is still controversially discussed. H19 was described to work either as a tumor suppressor in vitro and in vivo, or to have oncogenic features. This review attempts to survey the conflicting study results and tries to elucidate the potential reasons for the contrary findings, i.e., different methods, models, or readout parameters. This review encompasses in vitro and in vivo models as well as studies on human patient samples. Although the function of H19 in HCC remains elusive, a short outlook summarizes some ideas of using the H19 locus as a novel target for liver cancer therapy.

Widespread Dysregulation of Long Noncoding Genes Associated With Fatty Acid Metabolism, Cell Division, and Immune Response Gene Networks in Xenobiotic-exposed Rat Liver

Xenobiotic exposure dysregulates hundreds of protein-coding genes in mammalian liver, impacting many physiological processes and inducing diverse toxicological responses. Little is known about xenobiotic effects on long noncoding RNAs (lncRNAs), many of which have important regulatory functions. Here, we present a computational framework to discover liver-expressed, xenobiotic-responsive lncRNAs (xeno-lncs) with strong functional, gene regulatory potential and elucidate the impact of xenobiotic exposure on their gene regulatory networks. We assembled the long noncoding transcriptome of xenobiotic-exposed rat liver using RNA-seq datasets from male rats treated with 27 individual chemicals, representing 7 mechanisms of action (MOAs). Ortholog analysis was combined with coexpression data and causal inference methods to infer lncRNA function and deduce gene regulatory networks, including causal effects of lncRNAs on protein-coding gene expression and biological pathways. We discovered > 1400 liver-expressed xeno-lncs, many with human and/or mouse orthologs. Xenobiotics representing different MOAs often regulated common xeno-lnc targets: 123 xeno-lncs were dysregulated by ≥ 10 chemicals, and 5 xeno-lncs responded to ≥ 20 of the 27 chemicals investigated; 81 other xeno-lncs served as MOA-selective markers of xenobiotic exposure. Xeno-lnc-protein-coding gene coexpression regulatory network analysis identified xeno-lncs closely associated with exposure-induced perturbations of hepatic fatty acid metabolism, cell division, or immune response pathways, and with apoptosis or cirrhosis. We also identified hub and bottleneck lncRNAs, which are expected to be key regulators of gene expression. This work elucidates extensive networks of xeno-lnc-protein-coding gene interactions and provides a framework for understanding the widespread transcriptome-altering actions of foreign chemicals in a key-responsive mammalian tissue.

Cholangiocyte-Derived Exosomal lncRNA H19 Promotes Macrophage Activation and Hepatic Inflammation under Cholestatic Conditions

Activation of hepatic macrophages represents the critical driving force to promote cholestatic liver injury. Exosomes, as important small extracellular vesicles released by almost all types of cells, contribute to intercellular communication. We previously reported that cholangiocyte-derived exosomal long noncoding RNA (lncRNA) H19 plays a vital role in disrupting bile acid homeostasis in hepatocytes and promoting the activation of hepatic stellate cells (HSCs). Exosomal H19 derived from cholangiocytes was rapidly taken up by Kupffer cells. However, the mechanistic links between exosomal lncRNA H19 and macrophage-driven inflammation in cholestasis remain unclear. Here, we reported that the hepatic H19 level was closely correlated with macrophage activation and hepatic fibrosis in both Mdr2^-/- and bile duct ligation (BDL) cholestatic mouse models, as well as in human primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC) patients. Exosomal H19 significantly induced the expression and secretion of chemokine (C–C motif) ligand 2 (CCL-2) and interleukin 6 (IL-6) in Kupffer cells. H19-enriched exosomes enhanced the activation M1 polarization of Kupffer cells and promoted the recruitment and differentiation of bone marrow-derived macrophages, which were inhibited by a CCL-2 pharmacological inhibitor. In conclusion, Cholangiocyte-derived exosomal H19 played a critical role in macrophage activation, differentiation, and chemotaxis through CCL-2/CCR-2 signaling pathways, which represent a therapeutic target for cholestatic liver diseases.

Timp3 deficiency affects the progression of DEN-related hepatocellular carcinoma during diet-induced obesity in mice

AIM

Obesity and low-grade inflammation are associated with an increased risk of hepatocellular carcinoma (HCC), a leading cause of cancer-related death worldwide. The tissue inhibitor of metalloproteinase (TIMP) 3, an endogenous inhibitor of protease activity that represents a key mediator of inflammation, is reduced in inflammatory metabolic disorders and cancer. In contrast, Timp3-deficient mice (Timp3^-/-) are highly resistant to developing HCC in response to a diethylnitrosamine (DEN); therefore, we aimed to elucidate the biological role of genetic loss of Timp3 in obesity-related hepatocarcinogenesis.

METHODS

Fourteen-day-old male wild-type (wt) and Timp3^-/- mice were injected with 25 mg/kg DEN or an equal volume of saline. After 4 weeks, mice were randomized into two dietary groups and fed either normal or high-fat diet and allowed to grow until 32 weeks of age. Liver histological features were analyzed, and differentially expressed genes in the liver were quantified.

RESULTS

In Timp3^-/- mice fed with the obesogenic diet, despite the increase in liver steatosis and inflammation, both the number of tumors and the total tumor size are significantly reduced 30 weeks post-DEN injection, compared to control mice. Moreover, Timp3 deletion in hepatocarcinogenesis during obesity is associated with a reduction in FoxM1 transcriptional activity through H19/miR-675/p53 pathway.

CONCLUSIONS

This study suggests that Timp3 ablation leads to cell cycle perturbation, at least in part by repressing FoxM1 transcriptional activity through H19/miR-675/p53 pathway.

The role of long non-coding RNA H19 in breast cancer

Breast cancer is the most common malignant tumor in women in the majority of countries, such as China, Britain and Australia, and its morbidity and mortality rates remain very high. Long non-coding RNAs (lncRNAs) are non-coding RNAs (ncRNAs) >200 nucleotides in length that lack open reading frames. LncRNA H19 is a transcription product of the H19 gene, and the aberrant expression of H19 can be demonstrated in various types of tumor cell. The purpose of the present review was to elaborate the role of H19 in breast cancer. H19 can regulate gene expression in breast cancer at multiple levels, including epigenetic, transcriptional and posttranscriptional. The abnormal expression of H19 is closely associated with the tumorigenesis and progression of breast cancer via different underlying molecular mechanisms, such as encoding microRNA-675, competing endogenous RNA regulation and interacting with MYC. A large number of clinical studies have suggested that H19 can serve as a potential biomarker for the diagnosis of breast cancer. High expression levels of H19 increases the drug resistance of breast cancer cells and is associated with poor prognosis within patients with breast cancer. Therefore, serum H19 levels may have momentous significance in the clinical setting.

Cholangiocyte-Derived Exosomal Long Noncoding RNA H19 Promotes Hepatic Stellate Cell Activation and Cholestatic Liver Fibrosis

Activation of hepatic stellate cells (HSCs) represents the primary driving force to promote the progression of chronic cholestatic liver diseases. We previously reported that cholangiocyte-derived exosomal long noncoding RNA-H19 (lncRNA-H19) plays a critical role in promoting cholestatic liver injury. However, it remains unclear whether cholangiocyte-derived lncRNA-H19 regulates HSC activation, which is the major focus of this study. Both bile duct ligation (BDL) and Mdr2 knockout (Mdr2^-/- ) mouse models were used. Wild-type and H19^{maternalΔExon1/+} (H19KO) mice were subjected to BDL. Mdr2^-/- H19^{maternalΔExon1/+} (DKO) mice were generated. Exosomes isolated from cultured mouse and human cholangiocytes or mouse serum were used for in vivo transplantation and in vitro studies. Fluorescence-labeled exosomes and flow cytometry were used to monitor exosome uptake by hepatic cells. Collagen gel contraction and bromodeoxyuridine assays were used to determine the effect of exosomal-H19 on HSC activation and proliferation. Mouse and human primary sclerosing cholangitis (PSC)/primary biliary cholangitis (PBC) liver samples were analyzed by real-time PCR, western blot analysis, histology, and immunohistochemistry. The results demonstrated that hepatic H19 level was closely correlated with the severity of liver fibrosis in both mouse models and human patients with PSC and PBC. H19 deficiency significantly protected mice from liver fibrosis in BDL and Mdr2^-/- mice. Transplanted cholangiocyte-derived H19-enriched exosomes were rapidly and preferentially taken up by HSCs and HSC-derived fibroblasts, and promoted liver fibrosis in BDL-H19KO mice and DKO mice. H19-enriched exosomes enhanced transdifferentiation of cultured mouse primary HSCs and promoted proliferation and matrix formation in HSC-derived fibroblasts. Conclusion: Cholangiocyte-derived exosomal H19 plays a critical role in the progression of cholestatic liver fibrosis by promoting HSC differentiation and activation and represents a potential diagnostic biomarker and therapeutic target for cholangiopathies.

Long Noncoding RNA GAS5 Acts As A Tumor Suppressor In Laryngeal Squamous Cell Carcinoma Via miR-21

Purpose

Long noncoding RNAs (lncRNAs) have been identified as an important class of noncoding RNAs that are deeply involved in multiple biological processes in tumorigenesis. This study is to investigate the critical roles and biological function of lncRNA growth arrest-specific 5 (GAS5) in tumorigenesis of laryngeal squamous cell carcinoma (LSCC).

Patients and methods

A total of 59 samples of LSCC and paired adjacent tissue, as well as corresponding clinicopathological information were collected. GAS5 expression in both LSCC tissues and human SUN1076 and SNU899 cell lines were analyzed by Real-time quantitative RT-PCR method. Ectopic expression of GAS5 by vector transfection in LSCC cell lines and followed by in vitro experiments was to investigate the critical roles and function of GAS5 in LSCC. Cell Counting Kit 8 (CCK8) assay and PE/7AAD Annexin V Apoptosis analysis was to evaluate cell proliferation ability and cell apoptosis. Co-transfection of GAS5 and miR-21 was to explore the interaction between GAS5 and miR-21 in LSCC. BAX and CDK6 protein level were analyzed by western blot method.

Results

This study demonstrated that GAS5 was significantly downregulated in LSCC tissue and human LSCC cell lines. GAS5 levels were correlated with the clinicopathological features of LSCC patients. In addition, the ectopic expression of GAS5 significantly inhibited cell proliferation and promoted apoptosis. Co-expression analyses indicated that GAS5 is negatively correlated with miR-21 in LSCC tissues. Overexpression of miR-21 eliminated GAS5-mediated cell apoptosis and proliferation suppression. Furthermore, GAS5, which upregulated BAX mRNA expression and downregulated CDK6 mRNA expression, was reversed by ectopic expression of miR-21.

Conclusion

GAS5 suppresses LSCC progression through the negative regulation of miR-21 and its targets involved in cell proliferation and apoptosis, indicating that GAS5 may serve as a biomarker and potential target for LSCC therapy.

lncRNA-D16366 Is a Potential Biomarker for Diagnosis and Prognosis of Hepatocellular Carcinoma

Background

Long non-coding RNAs (lncRTNAs) are a new focus in cancer research. Although lncRNAs have no protein coding capacity, they are important in epigenetics as well as in regulating gene expression, playing an important role in various cancers. In the current study, we investigated the roles of lncRNA-D16366 in hepatocellular carcinoma (HCC) and expected to find a new biomarker for early detection and prognosis of the disease.

Material/Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of lncRNA-D16366 in tissue and serum samples. The relationship between lncRNA-D16366 expression and clinicopathologic characteristics of patients with HCC was analyzed to estimate whether it was involved in malignancy development. Then, potential diagnostic and prognostic values were evaluated via receiver operating characteristic (ROC) curve, Kaplan-Meier and Cox regression analysis, respectively.

Results

lncRNA-D16366 was proved to be decreased in the tissues and serum among patients with HCC compared with the corresponding controls. Its expression was influenced by tumor size, HbsAg, portal vein tumor thrombus, Child-Pugh score, therapies, and neoplasm metastasis. It had high diagnostic value, with an AUC of 0.752, accompanied by a sensitivity of 65.5% and a specificity of 84.6%. In addition, it was related to the prognosis of HCC.

Conclusions

lncRNA-D16366 was decreased in HCC, and might be an independent diagnostic and prognostic indicator in the disease.

LncRNA-H19 promotes hepatic lipogenesis by directly regulating miR-130a/PPARγ axis in non-alcoholic fatty liver disease

Background: As one of the most common liver disorders worldwide, non-alcoholic fatty liver disease (NAFLD) begins with the abnormal accumulation of triglyceride (TG) in the liver. Long non-coding RNA-H19 was reported to modulate hepatic metabolic homeostasis in NAFLD. However, its molecular mechanism of NAFLD was not fully clear.

Methods:In vitro and in vivo models of NAFLD were established by free fatty acid (FFA) treatment of hepatocytes and high-fat feeding mice, respectively. Hematoxylin and Eosin (H&E) and Oil-Red O staining detected liver tissue morphology and lipid accumulation. Immunohistochemistry (IHC) staining examined peroxisome proliferator-activated receptor γ (PPARγ) level in liver tissues. ELISA assay assessed TG secretion. Luciferase assay and RNA pull down were used to validate regulatory mechanism among H19, miR-130a and PPARγ. The gene expression in hepatocytes and liver tissues was detected by quantitative real-time PCR (qRT-PCR) and Western blotting.

Results: H19 and PPARγ were up-regulated, while miR-130a was down-regulated in NAFLD mouse and cellular model. H&E and Oil-Red O staining indicated an increased lipid accumulation. Knockdown of H19 inhibited steatosis and TG secretion in FFA-induced hepatocytes. H19 could bind to miR-130a, and miR-130a could directly inhibit PPARγ expression. Meanwhile, miR-130a inhibited lipid accumulation by down-regulating NAFLD-related genes PPARγ, SREBP1, SCD1, ACC1 and FASN. Overexpression of miR-130a and PPARγ antagonist GW9662 inhibited lipogenesis and TG secretion, and PPARγ agonist GW1929 reversed this change induced by miR-130a up-regulation.

Conclusion: Knockdown of H19 alleviated hepatic lipogenesis via directly regulating miR-130a/PPARγ axis, which is a novel mechanistic role of H19 in the regulation of NAFLD.

Role of long non-coding RNAs in metabolic control

Long non-coding RNAs (lncRNAs) have emerged as pivotal regulators of gene expression by influencing various biological processes including proliferation, apoptosis, differentiation, and senescence. Accumulating evidence implicates lncRNAs in the maintenance of metabolic homeostasis; dysregulation of certain lncRNAs promotes the progression of metabolic disorders such as diabetes, obesity, and cardiovascular diseases. In this review, we discuss our understanding of lncRNAs implicated in metabolic control, focusing on in particular diseases arising from chronic inflammation, insulin resistance, and lipid homeostasis. We have analyzed lncRNAs and their molecular targets involved in the pathogenesis of chronic liver disease, diabetes, and obesity, and have discussed the rising interest in lncRNAs as diagnostic and therapeutic targets improving metabolic homeostasis. This article is part of a Special Issue entitled: ncRNA in control of gene expression edited by Kotb Abdelmohsen.

LncRNA-H19 activates CDC42/PAK1 pathway to promote cell proliferation, migration and invasion by targeting miR-15b in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the main causes of cancer-related death. This study aims to explore the role and underlying mechanism of H19 in HCC.

METHODS

qRT-PCR detected miR-15b-5p and H19 expression, as well as the mRNA level of EMT-associated genes. Western blotting detected protein level of EMT-associated genes. Immunohistochemistry (IHC) examined CDC42 in HCC tissues. Dual luciferase reporter assay verified the regulatory mechanism among H19, miR-15b and CDC42. Colony formation, wound healing assay, transwell, flow cytometry measured proliferation, migration, invasion and apoptosis, respectively.

RESULTS

H19 and CDC42 were up-regulated while miR-15b was down-regulated in HCC cells and tissues. miR-15b interacted with H19 and CDC42 3'-UTR. H19 knockdown inhibited proliferation, migration and invasion, and increased apoptosis, which was rescued by miR-15b inhibitor. H19 knockdown suppressed CDC42/PAK1 pathway and EMT progress.

CONCLUSION

H19 knockdown inhibited proliferation, migration and invasion, and promoted apoptosis of HCC cells via targeting miR-15b/CDC42/PAK1 axis.

Long non-coding RNA H19 inhibition promotes hyperglycemia in mice by upregulating hepatic FoxO1 levels and promoting gluconeogenesis

In a previous report from our laboratory, it was reported that hepatic levels of the long non-coding RNA (lncRNA), H19 are decreased in diabetic mice which elevates hepatic gluconeogenesis and glucose output. But, the mechanisms of H19 inhibition in elevating gluconeogenic genes' transcription and promoting hepatic glucose output were not known. In this study, we aimed to decipher this regulatory role of H19 on glucose metabolism and on FoxO1, an important transcriptional regulator of gluconeogenesis. While H19 inhibition in HepG2 cells increased the levels of FoxO1, its overexpression led to significant inhibition in FoxO1 levels, thereby identifying H19 as an important regulator of FoxO1. Our data also demonstrates that in the absence of H19, there is increased occupancy of p53 on the FoxO1 promoter that possibly is responsible for increased FoxO1 transcription. In vivo silencing of H19 in normal mice caused hyperglycemia, hyperinsulinemia and impaired glucose, insulin, and pyruvate tolerance. Serum triglyceride and cholesterol levels, however, did not show any change. H19 inhibition significantly elevated the hepatic levels of FoxO1 and all the gluconeogenic genes. While fasting increased gluconeogenic genes' transcription, the levels of H19 were decreased and these patterns reversed upon refeeding the mice. Thus, gluconeogenic genes and H19 levels show inverse patterns of expression, and these results indicate towards an important regulatory role of the lncRNA, H19. It acts as an upstream regulator of gluconeogenesis by regulating the transcription of FoxO1, an important transcription factor of gluconeogenic genes, and hence, regulates hepatic glucose metabolism. KEY MESSAGES: H19 regulates FoxO1 transcript and protein levels. H19 inhibition increases p53 occupancy on the FoxO1 promoter that promotes FoxO1 transcription. H19 inhibition in vivo induces hyperglycemia and impairs glucose, insulin, and pyruvate tolerance. In vivo H19 inhibition increases the hepatic transcript levels of gluconeogenic genes and FoxO1. Transcript levels of H19 and gluconeogenic genes are inversely regulated during fed and fasted states.

Prospects of Noncoding RNAs in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a global health problem and one of the most common malignant tumors. Recent studies have shown that noncoding RNAs (ncRNAs) contribute to the pathogenesis of hepatocellular carcinoma (HCC). These RNAs may be involved in a variety of pathological processes such as cell proliferation, apoptosis, angiogenesis, invasion, and metastasis. In addition, abnormal expression of ncRNAs in HCC may provide potential prognostic or diagnostic biomarkers. This review provides an overview of the role and potential applications of ncRNAs, miRNAs, lncRNAs, circRNAs, and snoRNAs in liver cancer.

Elevated hepatic expression of H19 long noncoding RNA contributes to diabetic hyperglycemia

Excessive hepatic glucose production (HGP) contributes significantly to the hyperglycemia of type 2 diabetes; however, the molecular mechanism underlying this dysregulation remains poorly understood. Here, we show that fasting temporally increases the expression of H19 long noncoding RNA (lncRNA) in nondiabetic mouse liver, whereas its level is chronically elevated in diet-induced diabetic mice, consistent with the previously reported chronic hepatic H19 increase in diabetic patients. Importantly, liver-specific H19 overexpression promotes HGP, hyperglycemia, and insulin resistance, while H19 depletion enhances insulin-dependent suppression of HGP. Using genome-wide methylation and transcriptome analyses, we demonstrate that H19 knockdown in hepatic cells alters promoter methylation and expression of Hnf4a, a master gluconeogenic transcription factor, and that this regulation is recapitulated in vivo. Our findings offer a mechanistic explanation of lncRNA H19's role in the pathogenesis of diabetic hyperglycemia and suggest that targeting hepatic H19 may hold the potential of new treatment for this disease.

Lnc-ing non-coding RNAs with metabolism and diabetes: roles of lncRNAs

Type 2 diabetes is a complex metabolic disorder characterized by insulin resistance and pancreatic β-cell dysfunction. Deregulated glucose and lipid metabolism are the primary underlying manifestations associated with this disease and its complications. Long non-coding RNAs (lncRNAs) are a novel class of functional RNAs that regulate a variety of biological processes by a diverse interplay of mechanisms including recruitment of epigenetic modifiers, transcriptional and post-transcriptional regulation, control of mRNA decay, and sequestration of transcription factors. Although the underlying causes that define the diabetic phenotype are extremely intricate, most of the studies in the last decades were mostly centered on protein-coding genes. However, current opinion in the recent past has authenticated the contributions of diverse lncRNAs as critical regulatory players during the manifestation of diabetes. The current review will highlight the importance of lncRNAs in regulating cellular processes that govern metabolic homeostasis in key metabolic tissues. A more in-depth understanding of lncRNAs may enable their exploitation as biomarkers or for therapeutic applications during diabetes and its associated complications.

The role of H19, a long non-coding RNA, in mouse liver postnatal maturation

H19 RNA is highly expressed at early postnatal ages and precipitously decreases at a specific time corresponding with increases in expression of genes important for mature liver function, such as drug metabolizing enzymes. H19’s role in the regulation of liver maturation is currently unknown. Using an H19 knockout mouse model to determine the role of H19 in liver development, we quantified gene expression for insulin growth factor signaling, Wnt signaling, key cytochrome P450 (P450) enzymes known to change as the liver develops, and fetal and adult plasma protein produced in liver. In mice lacking H19 expression, liver weights were significantly increased immediately after birth and significant increases were found in the number of actively proliferating cells. Increases in cell proliferation may be due to increases in β-catenin protein affecting Wnt signaling, increases in insulin-like growth factor 2 (IGF2) expression, and/or increases in insulin-like growth factor 1 receptor (IGF1R) expression at the protein level. Loss of targeted inhibition of IGF1R by microRNA 675 (miR-675) may be the cause of IGF1R increases, as miR-675 expression is also abrogated with loss of H19 expression in our model. P450 expression patterns were largely unchanged. No change in the production of plasma proteins was found, indicating H19 may not be important for liver maturation despite its role in controlling cell proliferation during liver growth. H19 may be important for normal liver development, and understanding how the liver matures will assist in predicting drug efficacy and toxicity in pediatric populations.