Hepatic miR-192-3p reactivation alleviates steatosis by targeting glucocorticoid receptor

The role of ncRNAs-mediated pyroptosis in diabetes and its vascular complications

Over the past decade, the prevalence of diabetes has increased significantly worldwide, leading to an increase in vascular complications of diabetes (VCD), such as diabetic cardiomyopathy (DCM), diabetic nephropathy (DN), and diabetic retinopathy (DR). Noncoding RNAs (ncRNAs), such as microRNAs (miRNAs), long Noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), play a key role in cellular processes, including the pathophysiology of diabetes and VCD via pyroptosis. ncRNAs (e.g., miR-17, lnc-MEG3, and lnc-KCNQ1OT1) can regulate pyroptosis in pancreatic β cells. Some ncRNAs are involved in VCD progression. For example, miR-21, lnc-KCNQ1OT1, lnc-GAS5, and lnc-MALAT1 were reported in DN and DCM, and lnc-MIAT was identified in DCM and DR. Herein, this review aimed to summarize recent research findings related to ncRNAs-mediated pyroptosis at the onset and progression of diabetes and VCD.

Metabolic memory: mechanisms and diseases

Metabolic diseases and their complications impose health and economic burdens worldwide. Evidence from past experimental studies and clinical trials suggests our body may have the ability to remember the past metabolic environment, such as hyperglycemia or hyperlipidemia, thus leading to chronic inflammatory disorders and other diseases even after the elimination of these metabolic environments. The long-term effects of that aberrant metabolism on the body have been summarized as metabolic memory and are found to assume a crucial role in states of health and disease. Multiple molecular mechanisms collectively participate in metabolic memory management, resulting in different cellular alterations as well as tissue and organ dysfunctions, culminating in disease progression and even affecting offspring. The elucidation and expansion of the concept of metabolic memory provides more comprehensive insight into pathogenic mechanisms underlying metabolic diseases and complications and promises to be a new target in disease detection and management. Here, we retrace the history of relevant research on metabolic memory and summarize its salient characteristics. We provide a detailed discussion of the mechanisms by which metabolic memory may be involved in disease development at molecular, cellular, and organ levels, with emphasis on the impact of epigenetic modulations. Finally, we present some of the pivotal findings arguing in favor of targeting metabolic memory to develop therapeutic strategies for metabolic diseases and provide the latest reflections on the consequences of metabolic memory as well as their implications for human health and diseases.

Therapeutic Effects of microRNAs on Nonalcoholic Fatty Liver Disease (NAFLD) and Nonalcoholic Steatohepatitis (NASH): A Systematic Review and Meta-Analysis

Nonalcoholic fatty liver disease (NAFLD) has emerged as a global health problem that affects people even at young ages due to unhealthy lifestyles. Without intervention, NAFLD will develop into nonalcoholic steatohepatitis (NASH) and eventually liver cirrhosis and hepatocellular carcinoma. Although lifestyle interventions are therapeutic, effective implementation remains challenging. In the efforts to establish effective treatment for NAFLD/NASH, microRNA (miRNA)-based therapies began to evolve in the last decade. Therefore, this systematic review aims to summarize current knowledge on the promising miRNA-based approaches in NAFLD/NASH therapies. A current systematic evaluation and a meta-analysis were conducted according to the PRISMA statement. In addition, a comprehensive exploration of PubMed, Cochrane, and Scopus databases was conducted to perform article searches. A total of 56 different miRNAs were reported as potential therapeutic agents in these studies. miRNA-34a antagonist/inhibitor was found to be the most studied variant (n = 7), and it significantly improved the hepatic total cholesterol, total triglyceride, Aspartate Aminotransferase (AST), and Alanine Transaminase (ALT) levels based on a meta-analysis. The biological processes mediated by these miRNAs involved hepatic fat accumulation, inflammation, and fibrosis. miRNAs have shown enormous therapeutic potential in the management of NAFLD/NASH, wherein miRNA-34a antagonist has been found to be an exceptional potential agent for the treatment of NAFLD/NASH.

Positive selection of somatically mutated clones identifies adaptive pathways in metabolic liver disease

Somatic mutations in nonmalignant tissues accumulate with age and injury, but whether these mutations are adaptive on the cellular or organismal levels is unclear. To interrogate genes in human metabolic disease, we performed lineage tracing in mice harboring somatic mosaicism subjected to nonalcoholic steatohepatitis (NASH). Proof-of-concept studies with mosaic loss of Mboat7, a membrane lipid acyltransferase, showed that increased steatosis accelerated clonal disappearance. Next, we induced pooled mosaicism in 63 known NASH genes, allowing us to trace mutant clones side by side. This in vivo tracing platform, which we coined MOSAICS, selected for mutations that ameliorate lipotoxicity, including mutant genes identified in human NASH. To prioritize new genes, additional screening of 472 candidates identified 23 somatic perturbations that promoted clonal expansion. In validation studies, liver-wide deletion of Tbx3, Bcl6, or Smyd2 resulted in protection against hepatic steatosis. Selection for clonal fitness in mouse and human livers identifies pathways that regulate metabolic disease.

Positive selection of somatically mutated clones identifies adaptive pathways in metabolic liver disease

Somatic mutations in non-malignant tissues accumulate with age and insult, but whether these mutations are adaptive on the cellular or organismal levels is unclear. To interrogate mutations found in human metabolic disease, we performed lineage tracing in mice harboring somatic mosaicism subjected to non-alcoholic steatohepatitis (NASH). Proof-of-concept studies with mosaic loss of Mboat7 , a membrane lipid acyltransferase, showed that increased steatosis accelerated clonal disappearance. Next, we induced pooled mosaicism in 63 known NASH genes, allowing us to trace mutant clones side-by-side. This in vivo tracing platform, which we coined MOSAICS, selected for mutations that ameliorate lipotoxicity, including mutant genes identified in human NASH. To prioritize new genes, additional screening of 472 candidates identified 23 somatic perturbations that promoted clonal expansion. In validation studies, liver-wide deletion of Bcl6, Tbx3, or Smyd2 resulted in protection against NASH. Selection for clonal fitness in mouse and human livers identifies pathways that regulate metabolic disease.

Highlights

Mosaic Mboat7 mutations that increase lipotoxicity lead to clonal disappearance in NASH. In vivo screening can identify genes that alter hepatocyte fitness in NASH. Mosaic Gpam mutations are positively selected due to reduced lipogenesis. In vivo screening of transcription factors and epifactors identified new therapeutic targets in NASH.

Liver Damage and microRNAs: An Update

One of the major organs in the body with multiple functions is the liver. It plays a central role in the transformation of macronutrients and clearance of chemicals and drugs. The serum biomarkers often used to indicate liver damage are not specifically for drug-induced liver injury (DILI) or liver injury caused by other xenobiotics, nor for viral infection. In this case, microRNAs (miRNAs) could play an exciting role as biomarkers of specific liver damage. In this review, we aimed to update the current literature on liver damage induced by drugs, as acute conditions and viral infections mediated by the hepatitis B virus (HBV) linked these two conditions to advanced research, with a focus on microRNAs as early biomarkers for liver damage. The undoubtable evidence that circulating miR-122 could be used as a human biomarker of DILI came from several studies in which a strong increase of it was linked with the status of liver function. In infancy, there is the possibility of an early miRNA detection for hepatitis B virus infection, but there are a lack of solid models for studying the HVB molecular mechanism of infection in detail, even if miRNAs do hold unrealized potential as biomarkers for early detection of hepatitis B virus infection mediated by HBV.

Profile analysis and functional modeling identify circular RNAs in nonalcoholic fatty liver disease as regulators of hepatic lipid metabolism

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease, associated with an outcome of hepatic fibrosis/cirrhosis and hepatocellular carcinoma. However, limited exploration of the underlying mechanisms hinders its prevention and treatment. To investigate the mechanisms of epigenetic regulation in NAFLD, the expression profile of circular RNA (circRNA) of rodents in which NAFLD was induced by a high-fat, high-cholesterol (HFHC) diet was studied. Modeling of the circRNA-microRNA (miRNA) -mRNA regulatory network revealed the functional characteristics of NAFLD-specific circRNAs. The targets and effects in the liver of such NAFLD-specific circRNAs were further assessed. Our results uncovered that the downregulation of 28 annotated circRNAs characterizes HFHC diet-induced NAFLD. Among the downregulated circRNAs, long intergenic non-protein coding RNA, P53 induced transcript (LNCPINT) -derived circRNAs (circ_0001452, circ_0001453, and circ_0001454) targeted both miR-466i-3p and miR-669c-3p. Their deficiency in NAFLD abrogated the circRNA-based inhibitory effect on both miRNAs, which further inactivated the AMPK signaling pathway via AMPK-α1 suppression. Inhibition of the AMPK signaling pathway promotes hepatic steatosis, depending on the transcriptional and translational upregulation of lipogenic genes, such as those encoding sterol regulatory element-binding protein 1 (SREBP1) and fatty acid synthase (FASN) in hepatocytes. The levels of LNCPINT-derived circRNAs displayed a negative association with hepatic triglyceride (TG) concentration. These findings suggest that loss of LNCPINT-derived circRNAs may underlie NAFLD via miR-466i-3p- and miR-669c-3p-dependent inactivation of the AMPK signaling pathway.

Role of non-coding RNAs on liver metabolism and NAFLD pathogenesis

Obesity and type 2 diabetes are major contributors to the growing prevalence of non-alcoholic fatty liver disease (NAFLD), a chronic liver condition characterized by accumulation of fat in individuals without a significant amount of alcohol intake. The NAFLD spectrum ranges from simple steatosis (early stages, known as NAFL), to non-alcoholic steatohepatitis (NASH), which can progress to fibrosis and cirrhosis or hepatocellular carcinoma. Obesity, type 2 diabetes, and NAFLD are strongly associated with insulin resistance. In the liver, insulin resistance increases hepatic glucose output, lipogenesis, and VLDL secretion, leading to a combination of hyperglycemia and hypertriglyceridemia. Aberrant gene expression is a hallmark of insulin resistance. Non-coding RNAs (ncRNAs) have emerged as prominent regulators of gene expression that operate at the transcriptional, post-transcriptional, and post-translational levels. In the last couple of decades a wealth of studies have provided evidence that most processes of liver metabolism are orchestrated by ncRNAs. This review focuses on the role of microRNAs, long non-coding RNAs and circular RNAs as coordinators of hepatic function, as well as the current understanding on how their dysregulation contributes to abnormal metabolism and pathophysiology in animal models of insulin resistance and NAFLD. Moreover, ncRNAs are emerging as useful biomarkers that may be able to discriminate between the different stages of NAFLD. The potential of ncRNAs as therapeutic drugs for NAFLD treatment and as biomarkers is discussed.

Human hepatocyte-enriched miRNA-192-3p promotes HBV replication through inhibiting Akt/mTOR signalling by targeting ZNF143 in hepatic cell lines

Previous studies have revealed multiple tissue- or cell-specific or enriched miRNA profiles. However, miRNA profiles enriched in hepatic cell types and their effect on HBV replication have not been well elucidated. In this study, primary human hepatocytes (PHHs), Kupffer cells (KCs), liver sinusoidal endothelial cells (LSECs), and hepatic stellate cells (HSCs) were prepared from liver specimens of non-HBV-infected patients. Four hepatic cell type-enriched miRNA profiles were identified from purified liver cells miRNA microarray assay. The results revealed that 12 miRNAs, including miR-122-5p and miR-192-3p were PHH-enriched; 9 miRNAs, including miR-142-5p and miR-155-5p were KC-enriched; 6 miRNAs, including miR-126-3p and miR-222-3p were LSEC-enriched; and 14 miRNAs, including miR-214-3p and miR-199a-3p were HSC-enriched. By testing the effect of 11 PHH-enriched miRNAs on HBV production, we observed that miR-192-3p had the greatest pro-virus effect in hepatic cell lines. Moreover, we further found that miR-192-3p promoted HBV replication and gene expression through inhibiting Akt/mTOR signalling by direct targeting of ZNF143 in HepG2.2.15 cells. Additionally, the serum and hepatic miR-192-3p expression levels were significantly higher in chronic hepatitis B patients than in healthy controls and serum miR-192-3p positively correlated with the serum levels of HBV DNA and HBsAg. Collectively, we identified miRNA profiles enriched in four hepatic cell types and revealed that PHH-enriched miR-192-3p promoted HBV replication through inhibiting Akt/mTOR signalling by direct targeting of ZNF143 in hepatic cell lines. Our study provides a specific perspective for the role of hepatic cell type-enriched miRNA in interaction with viral replication and various liver pathogenesis.

The Role and Mechanism of Oxidative Stress and Nuclear Receptors in the Development of NAFLD

The overproduction of reactive oxygen species (ROS) and consequent oxidative stress contribute to the pathogenesis of acute and chronic liver diseases. It is now acknowledged that nonalcoholic fatty liver disease (NAFLD) is characterized as a redox-centered disease due to the role of ROS in hepatic metabolism. However, the underlying mechanisms accounting for these alternations are not completely understood. Several nuclear receptors (NRs) are dysregulated in NAFLD, and have a direct influence on the expression of a set of genes relating to the progress of hepatic lipid homeostasis and ROS generation. Meanwhile, the NRs act as redox sensors in response to metabolic stress. Therefore, targeting NRs may represent a promising strategy for improving oxidation damage and treating NAFLD. This review summarizes the link between impaired lipid metabolism and oxidative stress and highlights some NRs involved in regulating oxidant/antioxidant turnover in the context of NAFLD, shedding light on potential therapies based on NR-mediated modulation of ROS generation and lipid accumulation.

Functional and Clinical Significance of Dysregulated microRNAs in Liver Cancer

Simple Summary

Liver cancer has a high mortality rate. Here, we retrospectively discuss the current progress and dilemmas in the clinical research and treatment of liver cancer. We primarily focus on microRNAs because of their extremely high value in applications and research. We discuss whether microRNAs can be used for the development of better biomarkers and/or therapeutic drugs, and address the difficulties, requirements for improved diagnostic technologies, and side effects related to microRNA-based drugs.

Abstract

Liver cancer is the leading cause of cancer-related mortality in the world. This mainly reflects the lack of early diagnosis tools and effective treatment methods. MicroRNAs (miRNAs) are a class of non-transcribed RNAs, some of which play important regulatory roles in liver cancer. Here, we discuss microRNAs with key impacts on liver cancer, such as miR-122, miR-21, miR-214, and miR-199. These microRNAs participate in various physiological regulatory pathways of liver cancer cells, and their modulation can have non-negligible effects in the treatment of liver cancer. We discuss whether these microRNAs can be used for better clinical diagnosis and/or drug development. With the advent of novel technologies, fast, inexpensive, and non-invasive RNA-based biomarker research has become a new mainstream approach. However, the clinical application of microRNA-based markers has been limited by the high sequence similarity among them and the potential for off-target problems. Therefore, researchers particularly value microRNAs that are specific to or have special functions in liver cancer. These include miR-122, which is specifically expressed in the liver, and miR-34, which is necessary for the replication of the hepatitis C virus in liver cancer. Clinical treatment drugs have been developed based on miR-34 and miR-122 (MRX34 and Miravirsen, respectively), but their side effects have not yet been overcome. Future research is needed to address these weaknesses and establish a feasible microRNA-based treatment strategy for liver cancer.

Glucocorticoid Receptor Signaling in Diabetes

Stress and depression increase the risk of Type 2 Diabetes (T2D) development. Evidence demonstrates that the Glucocorticoid (GC) negative feedback is impaired (GC resistance) in T2D patients resulting in Hypothalamic-Pituitary-Adrenal (HPA) axis hyperactivity and hypercortisolism. High GCs, in turn, activate multiple aspects of glucose homeostasis in peripheral tissues leading to hyperglycemia. Elucidation of the underlying molecular mechanisms revealed that Glucocorticoid Receptor (GR) mediates the GC-induced dysregulation of glucose production, uptake and insulin signaling in GC-sensitive peripheral tissues, such as liver, skeletal muscle, adipose tissue, and pancreas. In contrast to increased GR peripheral sensitivity, an impaired GR signaling in Peripheral Blood Mononuclear Cells (PBMCs) of T2D patients, associated with hyperglycemia, hyperlipidemia, and increased inflammation, has been shown. Given that GR changes in immune cells parallel those in brain, the above data implicate that a reduced brain GR function may be the biological link among stress, HPA hyperactivity, hypercortisolism and hyperglycemia. GR polymorphisms have also been associated with metabolic disturbances in T2D while dysregulation of micro-RNAs—known to target GR mRNA—has been described. Collectively, GR has a crucial role in T2D, acting in a cell-type and context-specific manner, leading to either GC sensitivity or GC resistance. Selective modulation of GR signaling in T2D therapy warrants further investigation.

Triclosan down-regulates fatty acid synthase through microRNAs in HepG2 cells

Triclosan is a promising candidate of fatty acid synthase (FASN) inhibitor by blocking FASN activity, but its effect on FASN expression and the underling epigenetic mechanism remain elusive. In this study, the effect of triclosan on FASN mRNA and protein expressions in human HepG2 cells and the regulatory role of microRNAs (miRNAs) in the downregulation of FASN induced by triclosan were explored through experiments and bioinformatics analysis. The results showed that triclosan not only directly inhibited FASN activity, but also significantly decreased FASN mRNA and protein levels in human liver HepG2 cells. Nine miRNAs targeting FASN mRNA degradation were identified by miRNA prediction tools, and the expression levels of these nine miRNAs were then detected by real-time quantitative PCR. Triclosan significantly increased the expressions of the six miRNAs, namely miR-15a, miR-107, miR-195, miR-424, miR-497 and miR-503, leading to the downregulation of FASN. Further investigation revealed that the six triclosan-upregulated miRNAs played an important regulatory role in lipid metabolism and cell cycle by gene ontology annotations and pathway analysis. Consistent with the results of bioinformatics analyses, triclosan significantly reduced the intracellular lipid content by triglyceride assay, oil red O, BODIPY 493/503 and Nile Red staining, thereby inhibiting the growth of HepG2 cells through apoptosis. Taken together, our study reveals that triclosan downregulates FASN expression through a variety of miRNAs, providing new insight for triclosan as a FASN inhibitor candidate to regulate lipid metabolism in human hepatoma cells.