Bcl2 is a critical regulator of bile acid homeostasis by dictating Shp and lncRNA H19 function

HSDL2 links nutritional cues to bile acid and cholesterol homeostasis

In response to energy and nutrient shortage, the liver triggers several catabolic processes to promote survival. Despite recent progress, the precise molecular mechanisms regulating the hepatic adaptation to fasting remain incompletely characterized. Here, we report the identification of hydroxysteroid dehydrogenase-like 2 (HSDL2) as a mitochondrial protein highly induced by fasting. We show that the activation of PGC1α-PPARα and the inhibition of the PI3K-mTORC1 axis stimulate HSDL2 expression in hepatocytes. We found that HSDL2 depletion decreases cholesterol conversion to bile acids (BAs) and impairs FXR activity. HSDL2 knockdown also reduces mitochondrial respiration, fatty acid oxidation, and TCA cycle activity. Bioinformatics analyses revealed that hepatic Hsdl2 expression positively associates with the postprandial excursion of various BA species in mice. We show that liver-specific HSDL2 depletion affects BA metabolism and decreases circulating cholesterol levels upon refeeding. Overall, our report identifies HSDL2 as a fasting-induced mitochondrial protein that links nutritional signals to BAs and cholesterol homeostasis.

Hepatocyte miR-21-5p-deficiency alleviates APAP-induced liver injury by inducing PPARγ and autophagy

Acetaminophen (APAP)-induced liver injury is one of the most frequent causes of acute liver failure worldwide. Significant increases in the levels of miRNA-21 in both liver tissues and plasma have been observed in APAP-overdosed animals and humans. However, the mechanistic effect of miRNA-21 on acute liver injury remains unknown. In this study, we generated a new hepatocyte-specific miRNA-21 knockout (miR-21-HKO) mouse line. miR-21-HKO and the background-matched sibling wild-type (WT) mice were treated with a toxic dose of APAP. Compared with WT mice, miR-21 HKO mice showed an increased survival, a reduction of necrotic hepatocytes, and an increased expression of light chain 3 beta, which suggested an autophagy activation. The expression of PPARγ was highly induced in the livers of miR-21-HKO mice after a 2-h APAP treatment, which preceded the activation of LC3B at the 12 h APAP treatment. miR-21 negatively regulated PPARγ protein expression by targeting its 3'-UTR. When PPARγ function was blocked by a potent antagonist GW9662 in miR-21-HKO mice, the autophage activation was significantly diminished, suggesting an indispensable role of PPARγ signaling pathway in miR-21-mediated hepatotoxicity. Taken together, hepatocyte-specific depletion of miRNA-21 alleviated APAP-induced hepatotoxicity by activating PPARγ and autophagy, demonstrating a crucial new regulatory role of miR-21 in APAP-mediated liver injury.

Epigenetic regulation of inflammation: The metabolomics connection

Epigenetic factors are considered the regulator of complex machinery behind inflammatory disorders and significantly contributed to the expression of inflammation-associated genes. Epigenetic modifications modulate variation in the expression pattern of target genes without affecting the DNA sequence. The current knowledge of epigenetic research focused on their role in the pathogenesis of various inflammatory diseases that causes morbidity and mortality worldwide. Inflammatory diseases are categorized as acute and chronic based on the disease severity and are regulated by the expression pattern of various genes. Hence, understanding the role of epigenetic modifications during inflammation progression will contribute to the disease outcomes and therapeutic approaches. This review also focuses on the metabolomics approach associated with the study of inflammatory disorders. Inflammatory responses and metabolic regulation are highly integrated and various advanced techniques are adopted to study the metabolic signature molecules. Here we discuss several metabolomics approaches used to link inflammatory disorders and epigenetic changes. We proposed that deciphering the mechanism behind the inflammation-metabolism loop may have immense importance in biomarkers research and may act as a principal component in drug discovery as well as therapeutic applications.

Role of sodium taurocholate cotransporting polypeptide (NTCP) in HBV-induced hepatitis: Opportunities for developing novel therapeutics

Hepatitis B is an infectious disease caused by the HBV virus. It presents a significant challenge for treatment due to its chronic nature and the potential for developing severe complications, including hepatocirrhosis and hepatocellular carcinoma. These complications not only cause physical and psychological distress to patients but also impose substantial economic and social burdens on both individuals and society as a whole. The internalization of HBV relies on endocytosis and necessitates the involvement of various proteins, including heparin sulfate proteoglycans, epidermal growth factor receptors, and NTCP. Among these proteins, NTCP is pivotal in HBV internalization and is primarily located in the liver's basement membrane. As a transporter of bile acids, NTCP also serves as a receptor facilitating HBV entry into cells. Numerous molecules have been identified to thwart HBV infection by stifling NTCP activity, although only a handful exhibit low IC50 values. In this systematic review, our primary focus dwells on the structure and regulation of NTCP, as well as the mechanism involved in HBV internalization. We underscore recent drug breakthroughs that specifically target NTCP to combat HBV infection. By shedding light on these advances, this review contributes novel insights into developing effective anti-HBV medications.

HMGB2 is a potential diagnostic marker and therapeutic target for liver fibrosis and cirrhosis

BACKGROUND

High mobility group proteins 1 and 2 (HMGB1 and HMGB2) are 80% conserved in amino acid sequence. The function of HMGB1 in inflammation and fibrosis has been extensively characterized. However, an unaddressed central question is the role of HMGB2 on liver fibrosis. In this study, we provided convincing evidence that the HMGB2 expression was significantly upregulated in human liver fibrosis and cirrhosis, as well as in several mouse liver fibrosis models.

METHODS

The carbon tetrachloride (CCl4) induced liver fibrosis mouse model was used. AAV8-Hmgb2 was utilized to overexpress Hmgb2 in the liver, while Hmgb2-/- mice were used for loss of function experiments. The HMGB2 inhibitor inflachromene and liposome-shHMGB2 (lipo-shHMGB2) were employed for therapeutic intervention.

RESULTS

The serum HMGB2 levels were also markedly elevated in patients with liver fibrosis and cirrhosis. Deletion of Hmgb2 in Hmgb2-/- mice or inhibition of HMGB2 in mice using a small molecule ICM slowed the progression of CCl4-induced liver fibrosis despite constant HMGB1 expression. In contrast, AAV8-mediated overexpression of Hmgb2 enchanced CCl4-incuded liver fibrosis. Primary hepatic stellate cells (HSCs) isolated from Hmgb2-/- mice showed significantly impaired transdifferentiation and diminished activation of α-SMA, despite a modest induction of HMGB1 protein. RNA-seq analysis revealed the induction of top 45 CCl4-activated genes in multiple signaling pathways including integrin signaling and inflammation. The activation of these genes by CCl4 were abolished in Hmgb2-/- mice or in ICM-treated mice. These included C-X3-C motif chemokine receptor 1 (Cx3cr1) associated with inflammation, cyclin B (Ccnb) associated with cell cycle, DNA topoisomerase 2-alpha (Top2a) associated with intracellular component, and fibrillin (Fbn) and fibromodulin (Fmod) associated with extracellular matrix.

CONCLUSION

We conclude that HMGB2 is indispensable for stellate cell activation. Therefore, HMGB2 may serve as a potential therapeutic target to prevent HSC activation during chronic liver injury. The blood HMGB2 level may also serve as a potential diagnostic marker to detect early stage of liver fibrosis and cirrhosis in humans.

Long noncoding RNAs: biogenesis, regulation, function, and their emerging significance in toxicology

The repertoire of regulatory noncoding RNAs (ncRNAs) has been enriched by the inclusion of long noncoding RNA (lncRNA) that are longer than 200 nt. Some of the currently known lncRNAs, were reported in the 1990s before the term lncRNA was introduced. These lncRNAs have diverse regulatory functions including regulation of transcription via interactions with proteins and RNAs, chromatin remodeling, translation, posttranslational protein modification, protein trafficking and cell signaling. Predictably, the dysregulation of lncRNA expression due to exposure to toxicants may precipitate adverse health consequences. Dysregulation of lncRNAs has also been implicated in various adverse human health outcomes. There is an increasing agreement that lncRNA expression profiling data needs to be closely examined to determine whether their altered expression can be used as biomarkers of toxicity as well as adverse human health outcomes. This review summarizes the biogenesis, regulation, function of lncRNA and their emerging significance in toxicology and disease conditions. Because our understanding of the lncRNA-toxicity relationship is still evolving, this review discusses this developing field using some examples.

M1 macrophage-derived exosomes promote autoimmune liver injury by transferring long noncoding RNA H19 to hepatocytes

Exosomes mediate intercellular communication by transmitting active molecules. The function of long noncoding RNA (lncRNA) H19 in autoimmune liver injury is unclear. Concanavalin A (ConA)-induced liver injury is well-characterized immune-mediated hepatitis. Here, we showed that lncRNA H19 expression was increased in the liver after ConA treatment, accompanied by increased exosome secretion. Moreover, injection of AAV-H19 aggravated ConA-induced hepatitis, with an increase in hepatocyte apoptosis. However, GW4869, an exosome inhibitor, alleviated ConA-induced liver injury and inhibited the upregulation of lncRNA H19. Intriguingly, lncRNA H19 expression in the liver was significantly downregulated, after macrophage depletion. Importantly, the lncRNA H19 was primarily expressed in type I macrophage (M1) and encapsulated in M1-derived exosomes. Furthermore, H19 was transported from M1 to hepatocytes via exosomes, and exosomal H19 dramatically induced hepatocytes apoptosis both in vitro and vivo. Mechanistically, H19 upregulated the transcription of hypoxia-inducible factor-1 alpha (HIF-1α), which accumulated in the cytoplasm and mediated hepatocyte apoptosis by upregulating p53. M1-derived exosomal lncRNA H19 plays a pivotal role in ConA-induced hepatitis through the HIF-1α-p53 signaling pathway. These findings identify M1 macrophage-derived exosomal H19 as a novel target for the treatment of autoimmune liver diseases.

Peroxisome Proliferator-Activated Receptor-γ as a Target and Regulator of Epigenetic Mechanisms in Nonalcoholic Fatty Liver Disease

Peroxisome proliferator-activated receptor-γ (PPARγ) belongs to the superfamily of nuclear receptors that control the transcription of multiple genes. Although it is found in many cells and tissues, PPARγ is mostly expressed in the liver and adipose tissue. Preclinical and clinical studies show that PPARγ targets several genes implicated in various forms of chronic liver disease, including nonalcoholic fatty liver disease (NAFLD). Clinical trials are currently underway to investigate the beneficial effects of PPARγ agonists on NAFLD/nonalcoholic steatohepatitis. Understanding PPARγ regulators may therefore aid in unraveling the mechanisms governing the development and progression of NAFLD. Recent advances in high-throughput biology and genome sequencing have greatly facilitated the identification of epigenetic modifiers, including DNA methylation, histone modifiers, and non-coding RNAs as key factors that regulate PPARγ in NAFLD. In contrast, little is still known about the particular molecular mechanisms underlying the intricate relationships between these events. The paper that follows outlines our current understanding of the crosstalk between PPARγ and epigenetic regulators in NAFLD. Advances in this field are likely to aid in the development of early noninvasive diagnostics and future NAFLD treatment strategies based on PPARγ epigenetic circuit modification.

High expression of centromere protein N as novel biomarkers for gastric adenocarcinoma

BACKGROUND

The role and mechanism of centromeric protein N (CENP-N), which has been associated with the development of various cancer types, are yet unclear in stomach adenocarcinoma (STAD).

METHODS

Data from the Cancer Genome Atlas and Genotype-Tissue Expression were used to determine whether CENP-N expression was altered in STAD tumors compared to normal tissues. Xiantao was used to perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG) enrichment analysis on CENP-N. The relationship between CENP-N expression and immune cell infiltration was assessed using TCGA database. The expression of CENP-N in STAD and surrounding tissues was confirmed using immunohistochemical staining and the correlation between CENP-N expression and clinicopathological characteristics was examined. The effects of CENP-N knockdown by siRNA on proliferation were measured by CCK-8 and EdU assays in AGS cells. Following siRNA transfection, flow cytometry was performed to evaluate cell cycle and apoptotic alterations in AGS cells. The effect of CENP-N knockdown on the expression level of related proteins was detected by Westren blot.

RESULTS

CENP-N was highly expressed in STAD tissues, which was confirmed by our immunohistochemistry results. The degree of invasion, TNM stage, and lymph node metastases were all strongly associated with CENP-N expression. CENP-N was essential for the cell cycle, DNA replication, chromosomal segregation, and nuclear division; there was a positive correlation between CENP-N expression and infiltrating Th2 and NK CD56dim cells and a negative correlation between CENP-N expression and mast, pDC, NK, and B cell infiltration. When CENP-N expression in AGS cells was knocked down, cell proliferation dramatically reduced (p < .05) and the percentage of cells in the S and G2-M phases decreased significantly (p < .05). Silencing CENP-N significantly promoted the apoptosis of AGS cells (p < .05). Mechanistic investigations showed that silencing CENP-N expression may inhibit STAD proliferation through the Cyclin E1 and promote STAD apoptosis through the Bcl-2/Bax.

CONCLUSION

According to our data, CENP-N acts as an oncogene in STAD and may be a viable therapeutic target.

An effective method for preventing cholestatic liver injury of Aucklandiae Radix and Vladimiriae Radix: Inflammation suppression and regulate the expression of bile acid receptors

ETHNOPHARMACOLOGICAL RELEVANCE

Aucklandiae Radix (AR) and Vladimiriae Radix (VR) were used to treat gastrointestinal, liver and gallbladder diseases at practice. In most conditions, VR was used to be a substitute of AR or a local habit may attribute to the same main active ingredients Costunolide and Dehydrocostus lactone, which presented many similar pharmacological activities. However, other different lactone compounds in AR and VR also play a role in disease treatment, so the difference in therapeutic effects of AR and VR in related diseases needs to be further studied.

AIMS OF THE STUDY

Revealing the differences between the chemical compounds of the total lactone extracts of AR and VR (TLE of AR and VR) and the differences in the protective effects of cholestatic liver injury to ensure rational use of AR and VR.

STUDY DESIGN AND METHODS

The macroporous adsorption resin was used to purify and enrich the lactone compounds to obtain the total lactone extracts of AR and VR. HPLC-PDA was used to obtain the data to establish chemical fingerprint and chemometric analysis to compare similarities and differences between TLE of AR and VR. The pharmacodynamic experiment revealed how TLE of AR and VR to show protect effects on cholestatic liver injury.

RESULTS

Similarity analysis results showed TLE of AR and VR had a high similarity (>0.9). Nevertheless, difference analysis results showed 4 compounds, Costunolide, Dehydrocostus lactone, 3β-acetoxy-11β-guaia-4 (15), 10 (14)-diene-12,6α-olide and vladinol F may contribute to the differences between them. The pharmacodynamics experiments results showed the TLE of AR and VR affected the different liver cholate-associated transporters mRNA expression (TLE of AR up-regulated CYP7A1, TLE of VR down-regulated FXR and BSEP), the TLE of AR and VR had an effect to regulate biochemical indicators (AST, ALT, ALP, TBA) of liver function, and TLE of VR was better than TLE of AR in reducing the expression of inflammatory factors (IL-6 and IL-1β).

CONCLUSION

The liver protection of AR and VR have been confirmed, but the differences of material basis and mechanism of drug efficacy needed further study to guarantee formulation research and provide theoretical references for clinical rational applications of AR and VR.

Bile acids and their receptors: modulators and therapeutic targets in liver inflammation

Bile acids participate in the intestinal emulsion, digestion, and absorption of lipids and fat-soluble vitamins. When present in high concentrations, as in cholestatic liver diseases, bile acids can damage cells and cause inflammation. After the discovery of bile acids receptors about two decades ago, bile acids are considered signaling molecules. Besides regulating bile acid, xenobiotic, and nutrient metabolism, bile acids and their receptors have shown immunomodulatory properties and have been proposed as therapeutic targets for inflammatory diseases of the liver. This review focuses on bile acid-related signaling pathways that affect inflammation in the liver and provides an overview of the preclinical and clinical applications of modulators of these pathways for the treatment of cholestatic and autoimmune liver diseases.

The Role of Epigenetics in Primary Biliary Cholangitis

Primary Biliary Cholangitis (PBC) is a rare autoimmune disease of the liver, affecting mostly females. There is evidence that epigenetic changes have a pathogenic role in PBC. Epigenetic modifications are related to methylation of CpG DNA islands, post-translational modifications of histone proteins, and non-coding RNAs. In PBC, there are data showing a dysregulation of all these levels, especially in immune cells. In addition, epigenetics seems to be involved in complex phenomena such as X monosomy or abnormalities in the process of X chromosome inactivation, which have been reported in PBC and appear to influence its sex imbalance and pathogenesis. We review here historical data on epigenetic modifications in PBC, present new data, and discuss possible links among X-chromosome abnormalities at a genetic and epigenetic level, PBC pathogenesis, and PBC sex imbalance.

Recent Advances of LncRNA H19 in Diabetes LncRNA H19 in Diabetes

Diabetes mellitus (DM) causes damage to major organs, including the heart, liver, brain, kidneys, eyes, and blood vessels, threatening the health of the individuals. Emerging evidence has demonstrated that lncRNAs has important functions in the pathogenesis of human diseases, such as cancers, neurodegenerative diseases, cardiac fibroblast phenotypes, hypertension, heart failure, atherosclerosis and diabetes. Recently, H19, a lncRNA, has been reported to shown to participate in the regulatory process of muscle differentiation, glucose metabolism, and tumor metastasis, as well as endometrial development. However, the roles of H19 in DM were still not completely understood. This review was conducted to summarize the functions of H19 in diabetes and discuss the challenges and possible strategies of H19 in DM.

MiR-200c-3p targets SESN1 and represses the IL-6/AKT loop to prevent cholangiocyte activation and cholestatic liver fibrosis

Cholestasis causes ductular reaction in the liver where the reactive cholangiocytes not only proliferate but also gain a neuroendocrine-like phenotype, leading to inflammatory cell infiltration and extracellular matrix deposition and contributing to the development and progression of cholestatic liver fibrosis. This study aims to elucidate the role of miR-200c in cholestasis-induced biliary liver fibrosis and cholangiocyte activation. We found that miR-200c was extremely abundant in cholangiocytes but was reduced by cholestasis in a bile duct ligation (BDL) mouse model; miR-200c was also decreased by bile acids in vitro. Phenotypically, loss of miR-200c exacerbated cholestatic liver injury, including periductular fibrosis, intrahepatic inflammation, and biliary hyperplasia in both the BDL model and the 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) model. We identified sestrin 1 (SESN1) as a target of miR-200c. Sesn1^-/--BDL mice showed mitigation of cholestatic liver injury. On a molecular level, the pro-proliferative IL-6/AKT feedback loop was activated in Mir200c^-/- livers but was inhibited in Sesn1^-/- livers upon cholestasis in mice. Furthermore, rescuing expression of miR-200c by the adeno-associated virus serotype 8 ameliorated BDL-induced liver injury in Mir200c^-/- mice. Taken together, this study demonstrates that miR-200c restrains the proliferative and neuroendocrine-like activation of cholangiocytes by targeting SESN1 and inhibiting the IL-6/AKT feedback loop to protect against cholestatic liver fibrosis. Our findings provide mechanistic insights regarding biliary liver fibrosis, which may help to reveal novel therapeutic targets for the treatment of cholestatic liver injury and liver fibrosis.

The Roles and Mechanisms of lncRNAs in Liver Fibrosis

Long non-coding RNAs (lncRNAs) can potentially regulate all aspects of cellular activity including differentiation and development, metabolism, proliferation, apoptosis, and activation, and benefited from advances in transcriptomic and genomic research techniques and database management technologies, its functions and mechanisms in physiological and pathological states have been widely reported. Liver fibrosis is typically characterized by a reversible wound healing response, often accompanied by an excessive accumulation of extracellular matrix. In recent years, a range of lncRNAs have been investigated and found to be involved in several cellular-level regulatory processes as competing endogenous RNAs (ceRNAs) that play an important role in the development of liver fibrosis. A variety of lncRNAs have also been shown to contribute to the altered cell cycle, proliferation profile associated with the accelerated development of liver fibrosis. This review aims to discuss the functions and mechanisms of lncRNAs in the development and regression of liver fibrosis, to explore the major lncRNAs involved in the signaling pathways regulating liver fibrosis, to elucidate the mechanisms mediated by lncRNA dysregulation and to provide new diagnostic and therapeutic strategies for liver fibrosis.

Effect of lncRNA H19 on nerve degeneration and regeneration after sciatic nerve injury in rats

Hundreds of millions of people worldwide suffer from peripheral nerve damage resulting from car accidents, falls, industrial accidents, residential accidents, and wars. The purpose of our study was to further investigate the effects of Wallerian degeneration (WD) after rat sciatic nerve injury and to screen for critical long noncoding RNAs (lncRNAs) in WD. We found H19 to be essential for nerve degeneration and regeneration and to be highly expressed in the sciatic nerves of rats with WD. lncRNA H19 potentially impaired the recovery of sciatic nerve function in rats. H19 was mainly localized in the cytoplasm of Schwann cells (SCs) and promoted their migration. H19 promoted the apoptosis of dorsal root ganglion (DRG) neurons and slowed the growth of DRG axons. The lncRNA H19 may play a role in WD through the Wnt/β-catenin signaling pathway and is coexpressed with a variety of crucial mRNAs during WD. These data provide further insight into the molecular mechanisms of WD.

Long Noncoding RNAs and Human Liver Disease

Long noncoding RNAs (lncRNAs) are pervasively transcribed in the genome, exhibit a diverse range of biological functions, and exert effects through a variety of mechanisms. The sheer number of lncRNAs in the human genome has raised important questions about their potential biological significance and roles in human health and disease. Technological and computational advances have enabled functional annotation of a large number of lncRNAs. Though the number of publications related to lncRNAs has escalated in recent years, relatively few have focused on those involved in hepatic physiology and pathology. We provide an overview of evolving lncRNA classification systems and characteristics and highlight important advances in our understanding of the contribution of lncRNAs to liver disease, with a focus on nonalcoholic steatohepatitis, hepatocellular carcinoma, and cholestatic liver disease. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 17 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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.

Epigenetic Regulation of Hepatic Stellate Cell Activation and Macrophage in Chronic Liver Inflammation

Chronic liver inflammation is a complex pathological process under different stress conditions, and the roles of stellate cells and macrophages in chronic liver inflammation have been widely reported. Moderate liver inflammation can protect the liver from damage and facilitate the recovery of liver injury. However, an inflammatory response that is too intense can result in massive death of hepatocytes, which leads to irreversible damage to the liver parenchyma. Epigenetic regulation plays a key part in liver inflammation. This study reviews the regulation of epigenetics on stellate cells and macrophages to explore the new mechanisms of epigenetics on liver inflammation and provide new ideas for the treatment of liver disease.

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 RNAs-a new dimension in the molecular architecture of the bile acid/FXR pathway

Bile acids, regarded as the body's detergent for digesting lipids, also function as critical signaling molecules that regulate cholesterol and triglyceride levels in the body. Bile acids are the natural ligands of the nuclear receptor, FXR, which controls an intricate network of cellular pathways to maintain metabolic homeostasis. In recent years, growing evidence supports that many cellular actions of the bile acid/FXR pathway are mediated by long non-coding RNAs (lncRNAs), and lncRNAs are in turn powerful regulators of bile acid levels and FXR activities. In this review, we highlight the substantial progress made in the understanding of the functional and mechanistic role of lncRNAs in bile acid metabolism and how lncRNAs connect bile acid activity to additional metabolic processes. We also discuss the potential of lncRNA studies in elucidating novel molecular mechanisms of the bile acid/FXR pathway and the promise of lncRNAs as potential diagnostic markers and therapeutic targets for diseases associated with altered bile acid metabolism.

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.

Lnc-NEAT1 induces cell apoptosis and inflammation but inhibits proliferation in a cellular model of hepatic ischemia/reperfusion injury

OBJECTIVE

We aimed to investigate the effect of long non-coding RNA nuclear-enriched abundant transcript 1 (lnc-NEAT1) on regulating hepatocyte proliferation, apoptosis, and inflammation during hepatic ischemia/reperfusion (I/R) injury.

METHODS

Human liver cells (HL-7702) were cultured under glucose-free and oxygen-free conditions to construct the I/R injury model. Expression of lnc-NEAT1 was detected in this model and in normal cells. Plasmids of control overexpression [NC(+)], lnc-NEAT1 overexpression [NEAT1(+)], control short hairpin (sh)RNA [NC(-)], and lnc-NEAT1 shRNA [NEAT1(-)] were transfected into HL-7702 cells and subsequently subjected to I/R treatment. Cell proliferation, apoptosis, apoptosis-related proteins, and inflammatory cytokines were assessed.

RESULTS

Lnc-NEAT1 expression was elevated in the I/R group compared with the normal group. Cell proliferation was decreased in the NEAT1(+) group compared with the NC(+) group but increased in NEAT1(-) compared with NC(-). The apoptosis rate increased in the NEAT1(+) group compared with the NC(+) group but decreased in NEAT1(-) compared with NC(-). Western blot assay (detection of apoptosis-related proteins) showed similar results. Expression of interleukin-1β, interleukin-6, and tumor necrosis factor-α increased in the NEAT1(+) group compared with NC(+) but decreased in NEAT1(-) compared with NC(-).

CONCLUSION

Lnc-NEAT1 is overexpressed, induces cell apoptosis and inflammation, and inhibits proliferation during hepatic I/R injury.

Bile acids and their receptors in metabolic disorders

Bile acids are a large family of atypical steroids which exert their functions by binding to a family of ubiquitous cell membrane and nuclear receptors. There are two main bile acid activated receptors, FXR and GPBAR1, that are exclusively activated by bile acids, while other receptors CAR, LXRs, PXR, RORγT, S1PR2and VDR are activated by bile acids in addition to other more selective endogenous ligands. In the intestine, activation of FXR and GPBAR1 promotes the release of FGF15/19 and GLP1 which integrate their signaling with direct effects exerted by theother receptors in target tissues. This network is tuned in a time ordered manner by circadian rhythm and is critical for the regulation of metabolic process including autophagy, fast-to-feed transition, lipid and glucose metabolism, energy balance and immune responses. In the last decade FXR ligands have entered clinical trials but development of systemic FXR agonists has been proven challenging because their side effects including increased levels of cholesterol and Low Density Lipoproteins cholesterol (LDL-c) and reduced High-Density Lipoprotein cholesterol (HDL-c). In addition, pruritus has emerged as a common, dose related, side effect of FXR ligands. Intestinal-restricted FXR and GPBAR1 agonists and dual FXR/GPBAR1 agonists have been developed. Here we review the last decade in bile acids physiology and pharmacology.

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.

Renal AAV2-Mediated Overexpression of Long Non-Coding RNA H19 Attenuates Ischemic Acute Kidney Injury Through Sponging of microRNA-30a-5p

BACKGROUND

Renal ischemia-reperfusion (I/R) injury is a major cause of AKI. Noncoding RNAs are intricately involved in the pathophysiology of this form of AKI. Transcription of hypoxia-induced, long noncoding RNA H19, which shows high embryonic expression and is silenced in adults, is upregulated in renal I/R injury.

METHODS

Lentivirus-mediated overexpression, as well as antisense oligonucleotide-based silencing, modulated H19 in vitro. In vivo analyses used constitutive H19 knockout mice. In addition, renal vein injection of adeno-associated virus 2 (AAV2) carrying H19 caused overexpression in the kidney. Expression of H19 in kidney transplant patients with I/R injury was investigated.

RESULTS

H19 is upregulated in kidney biopsies of patients with AKI, in murine ischemic kidney tissue, and in cultured and ex vivo sorted hypoxic endothelial cells (ECs) and tubular epithelial cells (TECs). Transcription factors hypoxia-inducible factor 1-α, LHX8, and SPI1 activate H19 in ECs and TECs. H19 overexpression promotes angiogenesis in vitro and in vivo. In vivo, transient AAV2-mediated H19 overexpression significantly improved kidney function, reduced apoptosis, and reduced inflammation, as well as preserving capillary density and tubular epithelial integrity. Sponging of miR-30a-5p mediated the effects, which, in turn, led to target regulation of Dll4, ATG5, and Snai1.

CONCLUSIONS

H19 overexpression confers protection against renal injury by stimulating proangiogenic signaling. H19 overexpression may be a promising future therapeutic option in the treatment of patients with ischemic AKI.

Phosphorylation regulates cullin-based ubiquitination in tumorigenesis

Cullin-RING ligases (CRLs) recognize and interact with substrates for ubiquitination and degradation, and can be targeted for disease treatment when the abnormal expression of substrates involves pathologic processes. Phosphorylation, either of substrates or receptors of CRLs, can alter their interaction. Phosphorylation-dependent ubiquitination and proteasome degradation influence various cellular processes and can contribute to the occurrence of various diseases, most often tumorigenesis. These processes have the potential to be used for tumor intervention through the regulation of the activities of related kinases, along with the regulation of the stability of specific oncoproteins and tumor suppressors. This review describes the mechanisms and biological functions of crosstalk between phosphorylation and ubiquitination, and most importantly its influence on tumorigenesis, to provide new directions and strategies for tumor therapy.

Non-coding RNA crosstalk with nuclear receptors in liver disease

The dysregulation of nuclear receptors (NRs) underlies the pathogenesis of a variety of liver disorders. Non-coding RNAs (ncRNAs) are defined as RNA molecules transcribed from DNA but not translated into proteins. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are two types of ncRNAs that have been extensively studied for regulating gene expression during diverse cellular processes. NRs as therapeutic targets in liver disease have been exemplified by the successful application of their pharmacological ligands in clinics. MiRNA-based reagents or drugs are emerging as flagship products in clinical trials. Advancing our understanding of the crosstalk between NRs and ncRNAs is critical to the development of diagnostic and therapeutic strategies. This review summarizes recent findings on the reciprocal regulation between NRs and ncRNAs (mainly on miRNAs and lncRNAs) and their implication in liver pathophysiology, which might be informative to the translational medicine of targeting NRs and ncRNAs in liver disease.

The pro-oncogenic effect of the lncRNA H19 in the development of chronic inflammation-mediated hepatocellular carcinoma

The oncofetal long noncoding RNA (lncRNA) H19 is postnatally repressed in most tissues, and re-expressed in many cancers, including hepatocellular carcinoma (HCC). The role of H19 in carcinogenesis is a subject of controversy. We aimed to examine the role of H19 in chronic inflammation-mediated hepatocarcinogenesis using the Mdr2/Abcb4 knockout (Mdr2-KO) mouse, a well-established HCC model. For this goal, we have generated Mdr2-KO/H19-KO double knockout (dKO) mice and followed spontaneous tumor development in the dKO and control Mdr2-KO mice. Cellular localization of H19 and effects of H19 loss in the liver were determined in young and old Mdr2-KO mice. Tumor incidence and tumor load were both significantly decreased in the liver of dKO versus Mdr2-KO females. The expression levels of H19 and Igf2 were variable in nontumor liver tissues of Mdr2-KO females and were significantly downregulated in most matched tumors. In nontumor liver tissue of aged Mdr2-KO females, H19 was expressed mainly in hepatocytes, and hepatocyte proliferation was increased compared to dKO females. At an early age, dKO females displayed lower levels of liver injury and B-cell infiltration, with higher percentage of binuclear hepatocytes. In human samples, H19 expression was higher in females, positively correlated with cirrhosis (in nontumor liver samples) and negatively correlated with CTNNB1 (beta-catenin) mutations and patients' survival (in tumors). Our data demonstrate that the lncRNA H19 is pro-oncogenic during the development of chronic inflammation-mediated HCC in the Mdr2-KO mouse model, mainly by increasing liver injury and decreasing hepatocyte polyploidy in young mice.

The role of long noncoding RNA in lipid, cholesterol, and glucose metabolism and treatment of obesity syndrome

Obesity syndromes, characterized by abnormal lipid, cholesterol, and glucose metabolism, are detrimental to human health and cause many diseases, including obesity and type II diabetes. Increasing evidence has shown that long noncoding RNA (lncRNA), transcripts longer than 200 nucleotides that are not translated into proteins, play an important role in regulating abnormal metabolism in obesity syndromes. For the first time, we systematically summarize how lncRNA is involved in complex obesity metabolic syndromes, including the regulation of lipid, cholesterol, and glucose metabolism. Moreover, we discuss lncRNA involvement in food intake that mediates obesity syndromes. Furthermore, this review might shed new light on a lncRNA-based strategy for the prevention and treatment of obesity syndromes. Recent investigations support that lncRNA is a novel molecular target of obesity syndromes and should be emphasized. Namely, lncRNA plays a crucial role in the development of obesity syndrome process. Various lncRNAs are involved in the process of lipid, cholesterol, and glucose metabolism by regulating gene transcription, signaling pathway, and epigenetic modification of metabolism-related genes, proteins, and enzymes. Food intake could also induce abnormal expression of lncRNA associated with obesity syndrome, especially high-fat diet. Notably, some nanomolecules and natural extracts may target lncRNAs, associated with obesity syndrome, as a potential treatment for obesity syndromes.

Noncoding RNAs as Promising Diagnostic Biomarkers and Therapeutic Targets in Intestinal Fibrosis of Crohn's Disease: The Path From Bench to Bedside

Fibrosis is a major pathway to organ injury and failure, accounting for more than one-third of deaths worldwide. Intestinal fibrosis causes irreversible and serious clinical complications, such as strictures and obstruction, secondary to a complex pathogenesis. Under the stimulation of profibrotic soluble factors, excessive activation of mesenchymal cells causes extracellular matrix deposition via canonical transforming growth factor-β/Smads signaling or other pathways (eg, epithelial-to-mesenchymal transition and endothelial-to-mesenchymal transition) in intestinal fibrogenesis. In recent studies, the importance of noncoding RNAs (ncRNAs) stands out in fibrotic diseases in that ncRNAs exhibit a remarkable variety of biological functions in modulating the aforementioned fibrogenic responses. In this review, we summarize the role of ncRNAs, including the emerging long ncRNAs and circular RNAs, in intestinal fibrogenesis. Notably, the translational potential of ncRNAs as diagnostic biomarkers and therapeutic targets in the management of intestinal fibrosis is discussed based on clinical trials from fibrotic diseases in other organs. The main points of this review include the following: • Characteristics of ncRNAs and mechanisms of intestinal fibrogenesis • Wide participation of ncRNAs (especially the emerging long ncRNAs and circular RNAs) in intestinal fibrosis, including transforming growth factor-β signaling, epithelial-to-mesenchymal transition/endothelial-to-mesenchymal transition, and extracellular matrix remodeling • Translational potential of ncRNAs in the diagnosis and treatment of intestinal fibrosis based on clinical trials from fibrotic diseases in other organs.

All-Trans Retinoic Acid Rescues the Tumor Suppressive Role of RAR-β by Inhibiting LncHOXA10 Expression in Gastric Tumorigenesis

Numerous long noncoding RNAs (LncRNAs) were having recently been shown to be involved in cancer development, including gastric cancer (GC). However, the precise mechanism and treatments to target these molecules have rarely been studied. Thus, we aimed to investigate the function of LncHOXA10 in gastric tumorigenesis and targeted therapy. First, we measured the differences in LncHOXA10 and retinoic acid receptor β (RAR-β) levels in gastric cancer tissues and cell lines compared with those in noncancerous tissues and cell lines. We observed that LncHOXA10 was significantly upregulated in gastric cancer tissues and cell lines, whereas RAR-β showed the opposite trend. Subsequently, loss and gain of LncHOXA10 cell lines were constructed to determine whether LncHOXA10 plays a role in gastric tumorigenesis. The results showed that LncHOXA10 promoted the proliferation, migration, and invasion of cells, whereas apoptosis was markedly inhibited. Subsequently, mechanistic investigations revealed that LncHOXA10 can repress RAR-β expression and that all-trans retinoic acid (ATRA) can rescue the expression of RAR-β. Finally, we showed that ATRA can reverse the pro-cancerous function of LncHOXA10. We showed that LncHOXA10 may be a prognostic and therapeutic factor of gastric cancer by negatively regulating RAR-β. Furthermore, ATRA can inhibit the role of LncHOXA10 in gastric tumorigenesis.

Role of B Cell Lymphoma 2 in the Regulation of Liver Fibrosis in miR-122 Knockout Mice

MicroRNA-122 (miR-122) has been identified as a marker of various liver injuries, including hepatitis- virus-infection-, alcoholic-, and non-alcoholic steatohepatitis (NASH)-induced liver fibrosis. Here, we report that the extracellular miR-122 from hepatic cells can be delivered to hepatic stellate cells (HSCs) to modulate their proliferation and gene expression. Our published Argonaute crosslinking immunoprecipitation (Ago-CLIP) data identified several pro-fibrotic genes, including Ctgf, as miR-122 targets in mice livers. However, treating Ctgf as a therapeutic target failed to rescue the fibrosis developed in the miR-122 knockout livers. Alternatively, we compared the published datasets of human cirrhotic livers and miR-122 KO livers, which revealed upregulation of BCL2, suggesting its potential role in regulating fibrosis. Notably, ectopic miR-122 expression inhibited BCL2 expression in human HSC (LX-2) cells). Publicly available ChIP-seq data in human hepatocellular cancer (HepG2) cells and mice livers suggested miR-122 could regulate BCL2 expression indirectly through c-MYC, which was confirmed by siRNA-mediated depletion of c-MYC in Hepatocellular Carcinoma (HCC) cell lines. Importantly, Venetoclax, a potent BCL2 inhibitor approved for the treatment of leukemia, showed promising anti-fibrotic effects in miR-122 knockout mice. Collectively, our data demonstrate that miR-122 suppresses liver fibrosis and implicates anti-fibrotic potential of Venetoclax.

Role of ncRNAs in modulation of liver fibrosis by extracellular vesicles

Extracellular vesicles (EVs) are small membrane vesicles carrying bioactive lipids, proteins and nucleic acids of the cell of origin. In particular, EVs carry non-coding RNAs (ncRNAs) and the vesicle membrane may protect them from degradation. Once released within the extracellular space, EVs can transfer their cargo, including ncRNAs, to neighboring or distant cells, thus inducing phenotypical and functional changes that may be relevant in several physio-pathological conditions. This review provides an overview of the role of EV-carried ncRNAs in the modulation of liver fibrosis. In particular, we focused on EV-associated microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) involved into the development of liver fibrosis and on the potential use of EV-associated ncRNAs as diagnostic and prognostic biomarkers of liver fibrosis.

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.

Long non-coding RNA H19, a novel therapeutic target for pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with high mortality, which threats peoples’ health. Unfortunately, the pathogenesis of PDAC remains unclear. Recent studies have indicated that long non-coding RNAs (lncRNAs) can regulate the development and progression of malignant tumors through varying mechanisms. LncRNA H19 has a unique expression profile and can act as a sponger of specific miRNAs to regulate the pathogenic process of many diseases, including PDAC and several other types of cancers. Here, we review the research approaches to understanding the regulatory role of H19 and potential mechanisms in the progression of PDAC and other types of cancers and diseases. These studies suggest that H19 may be a novel therapeutic target for PDAC and our findings may open new revenues for scientific researches and development of valuable therapies for these diseases in the future.

Concise Review: Functional Roles and Therapeutic Potentials of Long Non-coding RNAs in Cholangiopathies

Long non-coding RNAs (lncRNAs) are RNAs with lengths exceeding 200 nucleotides that are not translated into proteins. It is well-known that small non-coding RNAs, such as microRNAs (miRNAs), regulate gene expression and play an important role in cholangiopathies. Recent studies have demonstrated that lncRNAs may also play a key role in the pathophysiology of cholangiopathies. Patients with cholangiopathies often develop cholangiocarcinoma (CCA), which is cholangiocyte-derived cancer, in the later stage. Cholangiocytes are a primary target of therapies for cholangiopathies and CCA development. Previous studies have demonstrated that expression levels of lncRNAs are altered in the liver of cholangiopathies or CCA tissues. Some lncRNAs regulate gene expression by inhibiting functions of miRNAs leading to diseased liver conditions or CCA progression, suggesting that lncRNAs could be a novel therapeutic target for those disorders. This review summarizes current understandings of functional roles of lncRNAs in cholangiopathies and seek their potentials for novel therapies.

Do genetic polymorphisms of B-cell CLL/lymphoma 2 confer susceptibility to anti-tuberculous therapy-associated drug-induced liver injury?

OBJECTIVES

The aim of this study was to identify the relationship between B-cell CLL/lymphoma 2 (BCL2) polymorphisms and susceptibility to anti-tuberculous therapy-associated drug-induced liver injury (ATT-DILI).

METHODS

A total of 746 tuberculosis (TB) patients were enrolled in this study. Twenty-one selected single nucleotide polymorphisms in BCL2 were analyzed by custom-by-design 2×48-Plex SNPscan kit. The allele and genotype frequencies between patients with and without ATT-DILI were compared using three different genetic models.

RESULTS

A total of 727/746 participants were successfully genotyped, and 112 of them were diagnosed with ATT-DILI. The A allele of rs8085707, G allele of rs76986960, and A allele of rs949037 conferred an increased risk of ATT-DILI, with estimated odd ratios (ORs) of 2.181 (95% confidence interval (CI) 1.345-3.536, p=0.001), 1.983 (95% CI 1.060-3.709, p=0.029), and 1.390 (95% CI 1.032-1.873, p=0.03), respectively. Bonferroni correction indicated that the A allele of rs8085707 was a risk factor for ATT-DILI (Bonferroni correction: p=0.026). The additive model suggested that patients with the AA genotype of rs8085707 had a significantly higher risk of ATT-DILI compared with those with the GG genotype (Bonferroni correction: p=0.036). The influence of BCL2 polymorphisms on clinical characteristics (clinical symptoms, disease subtypes, and laboratory indicators) was also identified.

CONCLUSIONS

This study is novel in suggesting an association between BCL2 polymorphisms and the risk of ATT-DILI.

The long non-coding RNA H19: an active player with multiple facets to sustain the hallmarks of cancer

Cancer cells exhibit hallmarks in terms of proliferation, resistance to cell death, angiogenesis, invasion, metastasis, and genomic instability. Despite the progress in cancer research and the comprehension of tumorigenesis mechanisms, cancer remains a major issue in public health. A better understanding of the molecular factors associated with the appearance or progression of cancer may allow the development of therapeutic alternatives. Increasing data highlight the role of long non-coding RNAs in many diseases, including cancer. The long non-coding RNA H19 was the first discovered riboregulator, and it has been shown to be involved at multiple steps of tumorigenesis. Indeed, this lncRNA exert its action at various molecular scales. Understanding the role of H19 in cancer progression may allow to set up therapeutic strategies to prevent tumor expansion and metastatic dissemination. In this review, we will summarize the overexpression of the long non-coding RNA H19 in several types of cancer and the multiple implications of the long non-coding RNA H19 in the different hallmarks that define human cancer.

TGF-β in Hepatic Stellate Cell Activation and Liver Fibrogenesis-Updated 2019

Liver fibrosis is an advanced liver disease condition, which could progress to cirrhosis and hepatocellular carcinoma. To date, there is no direct approved antifibrotic therapy, and current treatment is mainly the removal of the causative factor. Transforming growth factor (TGF)-β is a master profibrogenic cytokine and a promising target to treat fibrosis. However, TGF-β has broad biological functions and its inhibition induces non-desirable side effects, which override therapeutic benefits. Therefore, understanding the pleiotropic effects of TGF-β and its upstream and downstream regulatory mechanisms will help to design better TGF-β based therapeutics. Here, we summarize recent discoveries and milestones on the TGF-β signaling pathway related to liver fibrosis and hepatic stellate cell (HSC) activation, emphasizing research of the last five years. This comprises impact of TGF-β on liver fibrogenesis related biological processes, such as senescence, metabolism, reactive oxygen species generation, epigenetics, circadian rhythm, epithelial mesenchymal transition, and endothelial-mesenchymal transition. We also describe the influence of the microenvironment on the response of HSC to TGF-β. Finally, we discuss new approaches to target the TGF-β pathway, name current clinical trials, and explain promises and drawbacks that deserve to be adequately addressed.

Long Noncoding RNA H19 Contributes to Cholangiocyte Proliferation and Cholestatic Liver Fibrosis in Biliary Atresia

Biliary atresia (BA) is a neonatal liver disease featuring cholestasis and severe liver fibrosis (LF). Despite advances in the development of surgical treatment, lacking an early diagnostic marker and intervention of LF invariably leads to death from end-stage liver disease in the early years of life. We previously reported that knockout of sphingosine 1-phosphate receptor 2 (S1PR2) protected mice from bile duct ligation (BDL)-induced cholangiocyte proliferation and LF. Our recent studies further showed that both hepatic and serum exosomal long noncoding RNA H19 (lncRNAH19) levels are correlated with cholestatic injury in multidrug resistance 2 knockout (Mdr2^-/- ) mice. However, the role of lncRNAH19 in BA progression remains unclear. Here, we show that both hepatic and serum exosomal H19 levels are positively correlated with severity of fibrotic liver injuries in BA patients. H19 deficiency protects mice from BDL-induced cholangiocyte proliferation and LF by inhibiting bile-acid-induced expression and activation of S1PR2 and sphingosine kinase 2 (SphK2). Furthermore, H19 acts as a molecular sponge for members of the microRNA let-7 family, which results in up-regulation of high-mobility group AT-hook 2 (HMGA2), a known target of let-7 and enhancement of biliary proliferation. Conclusion: These results indicate that H19 plays a critical role in cholangiocyte proliferation and cholestatic liver injury in BA by regulating the S1PR2/SphK2 and let-7/HMGA2 axis. Serum exosomal H19 may represent a noninvasive diagnostic biomarker and potential therapeutic target for BA.

The hepatokine Tsukushi is released in response to NAFLD and impacts cholesterol homeostasis

Nonalcoholic fatty liver disease (NAFLD) prevails in obesity and is linked to several health complications including dyslipidemia and atherosclerosis. How exactly NAFLD induces atherogenic dyslipidemia to promote cardiovascular diseases is still elusive. Here, we identify Tsukushi (TSK) as a hepatokine induced in response to NAFLD. We show that both endoplasmic reticulum stress and inflammation promote the expression and release of TSK in mice. In humans, hepatic TSK expression is also associated with steatosis, and its circulating levels are markedly increased in patients suffering from acetaminophen-induced acute liver failure (ALF), a condition linked to severe hepatic inflammation. In these patients, elevated blood TSK levels were associated with decreased transplant-free survival at hospital discharge, suggesting that TSK could have a prognostic significance. Gain- and loss-of-function studies in mice revealed that TSK impacts systemic cholesterol homeostasis. TSK reduces circulating HDL cholesterol, lowers cholesterol efflux capacity, and decreases cholesterol-to-bile acid conversion in the liver. Our data identify the hepatokine TSK as a blood biomarker of liver stress that could link NAFLD to the development of atherogenic dyslipidemia and atherosclerosis.

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.

IGFBPrP1 accelerates autophagy and activation of hepatic stellate cells via mutual regulation between H19 and PI3K/AKT/mTOR pathway

BACKGROUND

Our previous study found that insulin-like growth factor binding protein-associated protein (IGFBPrP1) drives hepatic stellate cells (HSCs) activation, and IGFBPrP1 and transforming growth factor β1 (TGFβ1) likely interact with each other to promote HSCs activation. TGFβ1 reportedly promotes autophagy and contributes to HSCs activation; however, the mechanism between IGFBPrP1 and autophagy in liver fibrogenesis is yet unknown. Moreover, long noncoding RNA (lncRNA) H19 participates in autophagy regulation and plays a crucial function in liver fibrosis.

AIMS

To define the relationship between IGFBPrP1 and autophagy and the role of H19 in IGFBPrP1-induced hepatic fibrosis.

METHODS

IGFBPrP1 and autophagy were detected in bile duct ligation (BDL)-induced hepatic fibrosis. Adenovirus-mediated IGFBPrP1 was transfected into mouse liver and JS-1 cells with or without LY294002 or rapamycin to examine the effects of IGFBPrP1 on HSCs activation and autophagy as well as the PI3K/AKT/mTOR pathway. lncRNA H19 in liver fibrosis tissues and JS-1 cells induced by IGFBPrP1 were detected, then autophagy and HSCs activation level were detected in JS-1 cells by IGFBPrP1 with H19 overexpression or knowdown.

RESULTS

IGFBPrP1 expression and autophagy level were concomitantly increased in liver tissue with BDL-induced hepatic fibrosis. Furthermore, we found that IGFBPrP1 stimulated autophagy and HSCs activation in vivo and in vitro, and PI3K/AKT/mTOR signaling pathway was involved in the regulation of autophagy by IGFBPrP1. In addition, H19 promoted autophagy by interacting with the PI3K/AKT/mTOR pathway in IGFBPrP1-induced HSCs activation.

CONCLUSIONS

IGFBPrP1 promoted autophagy and contributed to HSCs activation via mutual regulation between H19 and the PI3K/AKT/mTOR pathway.

Long non-coding RNA H19, a negative regulator of microRNA-148b-3p, participates in hypoxia stress in human hepatic sinusoidal endothelial cells via NOX4 and eNOS/NO signaling

This study aimed at the participation of lncRNA H19, endothelial NADPH oxidases (NOX4) and miR-148b-3p in hypoxia stress in human hepatic sinusoidal endothelial cells (HHSEC), and clarifying the relationship among them. The expression of lnc H19, NOX4 and miR-148b-3p in cirrhotic patients and hypoxic HHSEC were measured by RT-PCR. The nitric oxide and hydrogen peroxide content in HHSEC were determined using ultraviolet chromatometry. The protein levels of NOX4, endothelial NOS (eNOS) and phosphorylated eNOS (p-eNOS) were measured via western blotting. The interaction between NOX4 promoter and lnc H19/miR-148b-3p was measured by dual-luciferase reporter gene detection system. The present results indicated that the expressions of NOX4 mRNA and lnc H19 were increased but miR-148b-3p was decreased in both cirrhotic patients and hypoxic HHSEC. Further, hypoxia induced the up-regulation of hydrogen peroxide and the down-regulation of eNOS/NO signaling in HHSEC. And these symptoms were ameliorated by lnc H19 shRNA and miR-148b-3p mimics. But the beneficial effects of lnc H19 shRNA and miR-148b-3p mimics were further abolished by miR-148b-3p inhibitor and NOX4 over-expression, respectively. In addition, NOX4 was a direct, negatively regulated target of miR-148b-3p, and miR-148b-3p was negatively regulated by lnc H19. Collectively, lnc H19 is a negatively regulator of microRNA-148b-3p, and participate in hypoxia stress in HHSEC via positively regulating NOX4 and negatively regulating eNOS/NO signaling.

Serum Metabolomic Profiling Identifies Key Metabolic Signatures Associated With Pathogenesis of Alcoholic Liver Disease in Humans

Alcoholic liver disease (ALD) develops in a subset of heavy drinkers (HDs). The goals of our study were to (1) characterize the global serum metabolomic changes in well‐characterized cohorts of controls (Cs), HDs, and those with alcoholic cirrhosis (AC); (2) identify metabolomic signatures as potential diagnostic markers, and (3) determine the trajectory of serum metabolites in response to alcohol abstinence. Serum metabolic profiling was performed in 22 Cs, 147 HDs, and 33 patients with AC using ultraperformance liquid chromatography–tandem mass spectrometry. Hepatic gene expression was conducted in Cs (n = 16) and those with AC (n = 32). We found progressive changes in the quantities of metabolites from heavy drinking to AC. Taurine‐conjugated bile acids (taurocholic acid [TCA], 127‐fold; taurochenodeoxycholic acid [TCDCA], 131‐fold; and tauroursodeoxycholic acid, 56‐fold) showed more striking elevations than glycine‐conjugated forms (glycocholic acid [GCA], 22‐fold; glycochenodeoxycholic acid [GCDCA], 22‐fold; and glycoursodeoxycholic acid [GUDCA], 11‐fold). This was associated with increased liver cytochrome P450, family 7, subfamily B, member 1 and taurine content (more substrates); the latter was due to dysregulation of homocysteine metabolism. Increased levels of GCDCA, TCDCA, GCA, and TCA positively correlated with disease progression from Child‐Pugh A to C and Model for End‐Stage Liver Disease scores, whereas GCDCA, GCA, and GUDCA were better predictors of alcohol abstinence. The levels of glucagon‐like peptide 1 (GLP‐1) and fibroblast growth factor (FGF) 21 but not FGF19 were increased in HDs, and all three were further increased in those with AC. Conclusion: Serum taurine/glycine‐conjugated bile acids could serve as noninvasive markers to predict the severity of AC, whereas GLP‐1 and FGF21 may indicate a progression from heavy drinking to AC.

H19 potentiates let-7 family expression through reducing PTBP1 binding to their precursors in cholestasis

Cholestasis induces the hepatic long non-coding RNA H19, which promotes the progression of cholestatic liver fibrosis. However, microRNAs that are dysregulated by H19 during cholestasis remain elusive. Using miRNA-sequencing analysis followed by qPCR validation, we identified marked upregulation of eight members of the let-7 family in cholestatic livers by bile duct ligation (BDL) and H19 overexpression. In particular, the expression of let-7a-1/7d/7f-1 was highly induced in H19-BDL livers but decreased in H19KO-BDL livers. Interestingly, H19 decreased the nuclear let-7 precursors as well as the primary transcripts of let-7a-1/7d/7f-1 levels in BDL mouse livers. Bioinformatics, RNA pull-down, and RNA immunoprecipitation (RIP) assays revealed that the crucial RNA-binding protein polypyrimidine tract-binding protein 1 (PTBP1), an H19 interaction partner, interacted with the precursors of let-7a-1 and let-7d and suppressed their maturation. Both PTBP1 and let-7 expression was differentially regulated by different bile acid species in hepatocyte and cholangiocyte cells. Further, H19 negatively regulated PTBP1's mRNA and protein levels but did not affect its subcellular distribution in BDL mouse livers. Moreover, we found that H19 restrained but PTBP1 facilitated the bioavailability of let-7 miRNAs to their targets. Taken together, this study revealed for the first time that H19 promoted let-7 expression by decreasing PTBP1's expression level and its binding to the let-7 precursors in cholestasis.