Human Hepatoma Huh7 Cells Research Articles

Loss of ATAD3A contributes to NAFLD through the accumulation of lipids and damaged mitochondria

Mitochondrial ATPase ATAD3A is essential for cholesterol transport, mitochondrial structure, and cell survival. However, the relationship between ATAD3A and non‐alcoholic fatty liver disease (NAFLD) is largely unknown. In this study, we found that ATAD3A was upregulated in the progression of NAFLD in livers from rats with diet‐induced non‐alcoholic steatohepatitis (NASH) and in human livers with NAFLD. CRISPR‐Cas9 was used to delete ATAD3A function in Huh7 human hepatocellular carcinoma cells to assess the influence of ATAD3A deletion on liver cells with free cholesterol (FC) overload induced by treatment with cholesterol plus 58035, an inhibitor for acetyl‐CoA acetyltransferase, the enzyme converting FC to cholesterol ester. The results showed that ATAD3A KO exacerbated FC accumulation under FC overload in Huh7 cells. Triglyceride (TG) levels were also significantly increased in ATAD3A KO Huh7 cells under FC overload and control conditions via inhibited lipolysis mediated by upregulation of perilipin 2. Moreover, loss of ATAD3A downregulated mitophagy‐associated PTEN‐induced kinase 1 expression in Huh7 cells under FC overload and control conditions, suggesting that ATAD3A KO blocks mitophagy. Consistently, mitochondrial mass was increased in ATAD3A KO cells under FC overload as indicated by mitochondrial protein translocase of outer mitochondrial membrane 20 (TOM20). The results also showed that loss of ATAD3A impaired mitochondrial basal respiration and ATP production in Huh7 cells under FC overload, accompanied by downregulation of mitochondrial ATP synthase. In conclusion, loss of ATAD3A promotes the progression of NAFLD through the accumulation of FC, TG, and damaged mitochondria in hepatocytes.

Osmosensing by cytoplasmic biomolecular condensates of antiviral MxA GTPase

Cellular and tissue‐level edema is a common feature of acute viral infections, including covid‐19. However, there is little understanding of the effects of tissue edema on antiviral effector mechanisms. In as much as defects in IFN‐α function (such as due to presence of autoantibodies) are now implicated in enhanced severity of covid‐19 disease, we investigated how hypoosmolarity and cellular edema might affect the antiviral activity of IFN‐α‐induced human MxA GTPase, a major antiviral effector against several RNA and DNA viruses. We had previously discovered that cytoplasmic human MxA existed in the cytoplasm in phase‐separated membraneless biomolecular condensates with a gel‐like internal consistency. The vesicular stomatitis virus (VSV) nucleocapsid (N) protein associated with such MxA condensates in cells exhibiting an antiviral phenotype. Unexpectedly, MxA condensates displayed rapid and reversible osmosensing properties. Condensates of both IFN‐α‐induced endogenous MxA and of exogenous GFP‐MxA expressed in human A549 lung and Huh7 hepatoma cells rapidly disassembled within 1‐2 min when cells were exposed to hypotonic buffer (approx. 50 mOsm), and rapidly reassembled into new structures within 1‐2 min of shifting of cells to isotonic culture medium (approx. 330 mOsm). GFP‐MxA condensates in cells continuously exposed to culture medium in the range one‐fourth, one‐third or one‐half isotonicity first rapidly disassembled within 1‐2 min, and then, in most cells. spontaneously reassembled 7‐15 min later into new structures. The data are consistent with cytoplasmic “crowding” as the mechanism driving MxA condensate formation. In terms of antiviral function, one 5 min cycle of disassembly and reassembly of GFP‐MxA condensates at 1 or 2 hr after VSV infection did not affect MxA antiviral activity. Additionally, continuous exposure of GFP‐MxA expressing A549 lung cells to culture medium at one‐fourth or one‐third tonicity (thus triggering a cycle of disassembly and slower spontaneous reassembly in the continued presence of hypotonic culture medium) together with a VSV challenge, left antiviral activity largely unaffected. Such cultures showed an increase in number of cells with VSV N colocalized with the reassembled GFP‐MxA condensates. The data reveal a novel property of MxA biomolecular condensates ‐ rapid and reversible osmosensing. Importantly, antiviral activity was largely unaffected by tonicity‐driven disassembly/reassembly mimicking conditions of cellular and tissue‐level edema.

Abstract 125: Reversible Epigenome Editing Of PCSK9 As A Therapeutic Strategy

Among the best-established causal risk factors for cardiovascular disease is the blood concentration of low-density lipoprotein cholesterol (LDL-C). Proprotein convertase subtilisin/kexin type 9 ( PCSK9 ), an antagonist to the LDL receptor, has emerged as a promising therapeutic target for the prevention of coronary heart disease. Current PCSK9 inhibitors are administered via subcutaneous injection, and their effects are short-lived. An alternative “one-and-done” strategy using genome editing to disrupt PCSK9 at the DNA level has been demonstrated in preclinical animal models, including non-human primates. However, concerns about the permanence and irreversibility of the genomic changes have been raised and might limit the acceptance of the therapies. Recently, a set of CRISPR-based epigenome editing tools, CRISPRoff and CRISPRon, were reported to regulate gene expression via site-directed methylation and demethylation of gene promoters, respectively. We hypothesized that these epigenome editing tools could durably and reversibly induce methylation changes in the PCSK9 promoter and thereby modulate its expression. We first screened CRISPRoff guide RNAs (gRNAs) targeting the PCSK9 promoter, individually and in dual combinations, for their ability to reduce PCSK9 expression in the human HuH-7 hepatoma cell line. We then performed long-term experiments with the lead candidate gRNAs. We found that these CRISPRoff gRNAs induced profound increases in methylation at CpG dinucleotides in the PCSK9 promoter, with up to 80% decreases in PCSK9 expression. These methylation increases and gene expression decreases have endured through >56 cell divisions so far, with only mild attenuation over time. Using the same gRNAs with CRISPRon in cells previously treated with CRISPRoff, we observed moderate decreases in methylation and increases in PCSK9 expression. Having established these effects in vitro , we are similarly assessing the durability and reversibility of epigenome editing using the lead gRNAs in a PCSK9 -humanized mouse model. Overall, this work provides a proof of concept of precise gene regulation via methylation and demethylation and suggests a potential new therapeutic approach for protection against coronary heart disease.

PPARα regulates the expression of human arylacetamide deacetylase involved in drug hydrolysis and lipid metabolism

Human arylacetamide deacetylase (AADAC) hydrolyzes various drugs containing an acetyl group, such as ketoconazole and rifampicin. Knowledge about the role of human AADAC in drug metabolism is accumulating, but the regulatory mechanism of its expression has not been elucidated. In mice, it has been suggested that Aadac expression may be regulated by peroxisome proliferator-activated receptor α (Pparα). This study examined whether human AADAC is regulated by PPARα, which widely regulates the expression of lipid metabolism-related genes. In human hepatoma Huh-7 cells, AADAC mRNA and protein levels were significantly increased by treatment with fenofibric acid and WY-14643, PPARα ligands. Knockdown and overexpression of PPARα resulted in decreased and increased expression of AADAC, respectively. Luciferase assays revealed that the direct repeat 1 (DR1) at −193/−181 in the AADAC promoter region is responsible for transactivation by PPARα. Chromatin immunoprecipitation assays revealed the binding of PPARα to DR1. Thus, it was demonstrated that human AADAC is regulated by PPARα through binding to DR1. Oil red O staining showed that overexpression of AADAC in Huh-7 cells suppressed lipid accumulation after treatment with free fatty acids. The suppression was restored by treatment with diisopropyl fluorophosphate, an AADAC inhibitor. The WY-14643-mediated suppression of lipid accumulation was restored by AADAC knockdown. These results suggested that AADAC has a role in suppressing cellular lipid accumulation. In conclusion, this study demonstrated the regulation of human AADAC by PPARα and its significance in lipid accumulation.

Novel efficacious microRNA-30c analogs reduce apolipoprotein B secretion in human hepatoma and primary hepatocyte cells

High plasma lipid levels have been demonstrated to increase cardiovascular disease risk. Despite advances in treatments to decrease plasma lipids, additional therapeutics are still needed because many people are intolerant or nonresponsive to these therapies. We previously showed that increasing cellular levels of microRNA-30c (miR-30c) using viral vectors or liposomes reduces plasma lipids and atherosclerosis. In this study, we aimed to synthesize potent miR-30c analogs that can be delivered to hepatoma cells without the aid of viral vectors and lipid emulsions. We hypothesized that modification of the passenger strand of miR-30c would increase the stability of miR-30c and augment its delivery to liver cells. Here, we report the successful synthesis of a series of miR-30c analogs by using different chemically modified nucleosides. In these analogs, we left the active sense strand untouched so that its biological activity remained unaltered, and we modified the passenger strand of miR-30c to enhance the stability and uptake of miR-30c by hepatoma cells through phosphorothiorate linkages and the addition of GalNAc. We show that these analogs significantly reduced apolipoprotein B secretion in Huh-7 human hepatoma cells and human primary hepatocytes without affecting apolipoprotein A1 secretion and cellular lipid levels. Our results provide a proof of concept that the passenger strand of miR-30c can be modified to increase its stability and delivery to cells while retaining the potency of the sense strand. We anticipate these miR-30c analogs will be useful in the development of more efficacious analogs for the treatment of hyperlipidemias and cardiovascular diseases.

MiR-383 Regulates Hepatic Lipid Homeostasis and Response to Dengue Virus Infection.

Recently, microRNAs (miRNAs), as endogenous noncoding RNAs that inhibit mRNA translation, have been identified to broadly possess functional roles in regulating cellular signaling and metabolic processes due to their chemical and biological properties. In addition, they have emerged to be of critical importance in modulating host-virus interactions, especially for RNA viruses. Herein, we discovered that miR-383-5p targets certain lipid and cholesterol biosynthetic pathways and restricts Dengue virus (DENV) infection in hepatic cells. Global transcriptomics analysis of Huh7 human hepatoma cells overexpressing miR-383-5p revealed enrichment of lipid and cholesterol metabolic processes. Bioinformatics analysis of genes repressed in miR-383-5p overexpressing cells divulged the repression of a key target PLA2G4A, a pro-viral host factor essential for the production of infectious DENV particles. Our study demonstrated the effectiveness of miRNA mimics as tools to study cellular signaling pathways that contribute to viral pathogenesis. Overall, our study identifies miR-383-5p as an interesting host factor during DENV propagation and highlights a potential therapeutic role in the regulation of hepatic lipid metabolism and an antiviral response to DENV.

Development and optimization of curcumin analog nano-bilosomes using 21.31 full factorial design for anti-tumor profiles improvement in human hepatocellular carcinoma: in-vitro evaluation, in-vivo safety assay

Curcumin (CU) is a natural polyphenolic phytoingredient. CU has anti-inflammatory, anti-oxidant, and anticancer activities. The poor solubility, bioavailability, and stability of CU diminish its clinical application. Hence, structural modification of CU is highly recommended. The CU analog; 3,5-bis(4-bromobenzylidene)-1-propanoylpiperidin-4-one (PIP) exhibited high stability, safety, and more potent antiproliferative activity against hepatocellular carcinoma. In the present study, nano-bilosomes (BLs) were formulated to augment PIP delivery and enhance its solubility. A 21.31 full factorial design was adopted to prepare the synthesized PIP-loaded BLs. Optimized F4 showed a biphasic release pattern extended over 24 h, with EE%, ZP, and PS of 90.21 ± 1.0%, −27.05 ± 1.08 mV, and 111.68 ± 1.4 nm. PIP-loaded BLs were tested for safety against a non-cancerous cell line (Wi-38) and for anticancer activity against the Huh-7 human hepatocellular carcinoma cells and compared to the standard anticancer drug doxorubicin (Dox). The anticancer selectivity index of PIP-loaded BLs recorded 420.55 against Huh-7 liver cancer cells, markedly higher than a CU suspension (18.959) or the Dox (20.82). The antiproliferative activity of nano-encapsulated PIP was roughly equivalent to Dox. PIP-loaded BLs, showed enhanced drug solubility, and enhanced anticancer effect, with lower toxicity and higher selectivity against Huh-7 liver cancer cells, compared to the parent CU.

The Lipid Droplet Knowledge Portal: A resource for systematic analyses of lipid droplet biology.

Lipid droplets (LDs) are organelles of cellular lipid storage with fundamental roles in energy metabolism and cell membrane homeostasis. There has been an explosion of research into the biology of LDs, in part due to their relevance in diseases of lipid storage, such as atherosclerosis, obesity, type 2 diabetes, and hepatic steatosis. Consequently, there is an increasing need for a resource that combines datasets from systematic analyses of LD biology. Here, we integrate high-confidence, systematically generated human, mouse, and fly data from studies on LDs in the framework of an online platform named the "Lipid Droplet Knowledge Portal" (https://lipiddroplet.org/). This scalable and interactive portal includes comprehensive datasets, across a variety of cell types, for LD biology, including transcriptional profiles of induced lipid storage, organellar proteomics, genome-wide screen phenotypes, and ties to human genetics. This resource is a powerful platform that can be utilized to identify determinants of lipid storage.

Cyclin dependent kinase 9 inhibition as a potential treatment for hepatocellular carcinoma.

425 Background: Composite cyclin dependent kinase (CDK) inhibition has shown potential as a treatment for hepatocellular carcinoma (HCC) in preclinical studies. We tested whether the specific inhibition of CDK9 was effective against HCC. Methods: The effects of two specific CDK9 inhibitors, BAY1143572 and AZD4573, on cell viability and apoptosis in HCC cell lines were examined. We tested the in vivo efficacy of CDK9 inhibition in mouse xenograft models of HuH7 human HCC cells and in an orthotopic model of BNL mouse HCC cells. Overexpression and knockdown of CDK9 were performed to confirm the efficacy of CDK9 inhibition. Results: Both BAY1143572 and AZD4573 exhibited potent antiproliferative activities in HCC cell lines including HuH7, HLE, and HepG2, regardless of the levels of c-myc expression while inhibiting the downstream signals of CDK9, such as the phosphorylation of RNA polymerase II. These 2 CDK9 inhibitors induced apoptosis in HCC cells and reduced the expression of antiapoptotic proteins such as myeloid cell leukemia-1, survivin, BimEL, and the X-linked inhibitor of apoptosis protein. Reduction of CDK9 expression through siRNA knockdown also reduced the phosphorylation of RNA polymerase II and the colony formations of HuH7 and HLE cells. In the xenograft studies, mice receiving either CDK9 inhibitor exhibited a significantly lower tumor growth rate than did the mice receiving vehicles. In the orthotopic model, the HCC growth in mice receiving BAY1143572 also tended to be slower than that in the control group. Overexpression of CDK9 in HuH7 cells reduced the efficacy of both CDK9 inhibitors. Conclusions: We demonstrated the in vitro and in vivo activity of CDK9 inhibition on multiple HCC cell lines. Our data support further clinical development of CDK9 inhibitors as a treatment for HCC.

Astragaloside IV suppresses migration and invasion of TGF-β1-induced human hepatoma HuH-7 cells by regulating Nrf2/HO-1 and TGF-β1/Smad3 pathways.

Astragaloside IV (AS-IV), one of the major compounds extract from Astragalus membranaceus, has shown attractive anti-cancer effects in certain malignancies. Oxidative stress (OS) is considered as a crucial factor in promoting the progression of hepatocellular carcinoma (HCC). In response to OS, nuclear factor erythroid 2-related factor 2 (Nrf2) upregulates and induces heme oxygenase 1 (HO-1) to combat oxidative damages. The phosphorylation of the COOH-terminal of Smad3 (pSmad3C) activates p21 to resist HCC progression, while the phosphorylation of the linker region of Smad3 (pSmad3L) up-regulates c-Myc transcription to exert promoting effect towards HCC. This study aimed to explore whether AS-IV suppresses migration and invasion of human hepatoma HuH-7 cells by regulating Nrf2/HO-1 and TGF-β1/Smad3 pathways. HuH-7 cells were induced with TGF-β1 (9 or 40pM) to establish HCC model in vitro and pretreated with AS-IV at different concentration (5, 10, and 20μM) for 24h. Cell proliferation, migration, invasion, and intracellular reactive oxygen species (ROS) of HuH-7 cells were measured. The expression of Nrf2, pSmad3C, Nrf2/pNrf2, HO-1, pSmad3C/3L, c-Myc, and p21 were detected. Exposure of HuH-7 cells to TGF-β1 enhanced the cell proliferation, migration, invasion, and ROS production. Pretreatment with AS-IV (5, 10, and 20μM) significantly reduced the cell proliferation, migration, invasion, and ROS production in HuH-7 cells. Furthermore, AS-IV increased the expressions of Nrf2/pNrf2, HO-1, pSmad3C, and p21, meanwhile reduced the expressions of pSmad3L and c-Myc. In conclusion, our study suggested that AS-IV inhibit HuH-7 cells migration and invasion, which related to activate Nrf2/HO-1 pathway, up-regulation pSmad3C/p21 pathway, and down-regulation pSmad3L/c-Myc pathway. The present research supports the notion that AS-IV may be a latent agent for the treatment of HCC.

Magnoflorine promotes Huh-7 cell apoptosis and autophagy by regulating PI3K/Akt/mTOR pathway

Hepatoma is a malignant tumor with high rates of heterogeneity, metastasis, and mortality. Currently, there is no effective treatment available for hepatoma. In order to treat advanced hepatoma in a better manner, new and more effective therapeutic targets still need to be developed. Magnoflorine (MGN) is a quaternary ammonium alkaloid with a variety of therapeutic properties. MGN inhibited the proliferation of lung cancer, breast cancer, glioma, and rhabdomyosarcoma cells, induced apoptosis, and blocked cell cycle. However, its possible effects on the progression of hepatoma are still indefinite. In this study, the effects of MGN on the progression of hepatoma in vitro and the underlying mechanisms were determined. MGN suppressed the proliferation, induced the autophagy, and stimulated the apoptosis of human hepatoma Huh-7 cells. Mechanically, MGN could regulate PI3K/AKT/mTOR pathway, which therefore affects the progression of hepatoma in vitro. Taken together, MGN affected Huh-7 cell proliferation, autophagy, and apoptosis, and might act as a promising therapeutic drug for treating hepatoma.

Liver Function Derangement in Patients with Severe Fever and Thrombocytopenia Syndrome.

Background and AimsPatients with severe fever with thrombocytopenia syndrome (SFTS) commonly show liver function impairment. This study aimed to characterize the liver function indices in SFTS patients and investigate their association with mortality.MethodsClinical information and laboratory results of 459 laboratory-confirmed SFTS patients, including 78 deceased and 381 surviving patients, were retrospectively analyzed. To explore the infectivity of SFTS caused by novel Bunyavirus (SFTSV) in hepatocytes, Huh7 human hepatoma cells were infected with various concentrations of SFTSV in vitro.ResultsThe proportion of SFTS patients developing liver injury during hospitalization was 73.2% (336/459); the hepatocellular injury was the predominant type. The median time to occurrence of liver injury from disease onset was 8 d. Liver injury in the deceased group occurred earlier than that in the surviving group. Alanine aminotransferase (ALT) level between 2–5 times upper limit of normal (ULN) at 4–6 d and between 5–15 ULN at 7–12 d of disease course were independent predictors of mortality. Alkaline phosphatase (ALP) >2 ULN at 7–9 d and elevated ALP at 10–12 days after disease onset were risk factors for death. ALT and aspartate transaminase (AST) levels were correlated with lymphocyte count and platelet-to-lymphocyte ratio (PLR). Total bilirubin (TB), ALT, AST levels showed positive correlation with viral load. In the in vitro experiment, SFTSV infected and replicated inside Huh7 cells.ConclusionsLiver injury is common in SFTS patients. ALT and ALP were independent predictors of SFTS-related mortality. Frequent monitoring and evaluation of liver function indices are needed for SFTS patients.

Cyclosporine as a novel treatment for amatoxin-containing mushroom poisoning: a case series

Ingestion of amatoxin-containing mushrooms can lead to fulminant hepatotoxicity and death. Despite recent interest in therapeutic options for amatoxin-exposed patients, there is no single, recommended treatment for amatoxin poisoning. Alpha-amanitin, the principal toxin in amatoxin-containing mushrooms, requires entry into hepatocytes via organic anion transporting polypeptide (OATP) 1B3 before the cascade of cellular events occurs leading to hepatocyte necrosis, liver failure, and in severe cases liver transplantation or death. Three patients managed through a single poison centre with confirmed amatoxin-containing mushrooms ingestions were treated with intravenous cyclosporine, a known potent OATP1B3 inhibitor, along with supportive care. All patients presented with classic delayed symptoms of nausea, vomiting and diarrhea. No patient progressed to fulminant hepatic failure, although two patients developed a transient rise in liver transaminases. All recovered and were discharged from hospital. No patient had an adverse effect from cyclosporine. In addition, we performed an in-vitro study of the role of cyclosporine in cultured HEK293T cells and human hepatoma Huh7 cells. Cyclosporine effectively inhibited OATP1B3-mediated uptake of alpha-amanitin, and improved cell viability of alpha-amanitin exposed cultured Huh7 cells. We conclude that IV cyclosporine, a drug readily available in most hospitals, may be useful to reduce hepatotoxicity from amatoxin poisoning.

Synthesis of Novel MicroRNA-30c Analogs to Reduce Apolipoprotein B Secretion in Human Hepatoma Cells.

Atherosclerosis, a condition characterized by thickening of the arteries due to lipid deposition, is the major contributor to and hallmark of cardiovascular disease. Although great progress has been made in lowering the lipid plaques in patients, the conventional therapies fail to address the needs of those that are intolerant or non-responsive to the treatment. Therefore, additional novel therapeutic approaches are warranted. We have previously shown that increasing the cellular amounts of microRNA-30c (miR-30c) with the aid of viral vectors or liposomes can successfully reduce plasma cholesterol and atherosclerosis in mice. To avoid the use of viruses and liposomes, we have developed new methods to synthesize novel miR-30c analogs with increasing potency and efficacy, including 2'-O-methyl (2'OMe), 2'-fluoro (2'F), pseudouridine (ᴪ), phosphorothioate (PS), and N-acetylgalactosamine (GalNAc). The discovery of these modifications has profoundly impacted the modern RNA therapeutics, as evidenced by their increased nuclease stability and reduction in immune responses. We show that modifications on the passenger strand of miR-30c not only stabilize the duplex but also aid in a more readily uptake by the cells without the aid of viral vectors or lipid emulsions. After uptake, the analogs with PS linkages and GalNAc-modified ribonucleotides significantly reduce the secretion of apolipoprotein B (ApoB) without affecting apolipoprotein A1 (ApoA1) in human hepatoma Huh-7 cells. We envision an enormous potential for these modified miR-30c analogs in therapeutic intervention for treating cardiovascular diseases. This protocol was validated in: J Biol Chem (2021), DOI: 10.1016/j.jbc.2022.101813.

Study Liver Cytochrome P450 3A4 Inhibition and Hepatotoxicity Using DMSO-Differentiated HuH-7 Cells.

Metabolically competent, inexpensive, and robust in vitro cell models are needed for studying liver drug-metabolizing enzymes and hepatotoxicity. Human hepatoma HuH-7 cells develop into a differentiated in vitro model resembling primary human hepatocytes after a 2-week dimethyl sulfoxide (DMSO) treatment. DMSO-differentiated HuH-7 cells express elevated cytochrome P450 3A4 (CYP3A4) enzyme gene expression and activity compared to untreated HuH-7 cells. This cell model could be used to study CYP3A4 inhibition by reversible and time-dependent inhibitors, such as drugs, food ingredients, and environmental chemicals. The DMSO-differentiated HuH-7 model is also a suitable tool for investigating hepatotoxicity. This chapter describes a detailed methodology for developing DMSO-differentiated HuH-7 cells, which are subsequently used for CYP3A4 inhibition and hepatotoxicity studies.

Longer Poly(U) Stretches in the 3'UTR Are Essential for Replication of the Hepatitis C Virus Genotype 4a Clone in in vitro and in vivo.

The 3′ untranslated region (UTR) of the hepatitis C virus (HCV) genome plays a significant role in replication including the poly(U) tract (You and Rice, 2008). Here we established an HCV clone that is infectious in vitro and in vivo, from an Egyptian patient with chronic HCV infection and hepatocellular carcinoma (HCC). First, we inoculated the patient plasma into a humanized chimeric mouse and passaged. We observed HCV genotype 4a propagation in the chimeric mouse sera at 1.7 × 107 copies/mL after 6 weeks. Next, we cloned the entire HCV sequence from the HCV-infected chimeric mouse sera using RT-PCR, and 5′ and 3′ RACE methodologies. We obtained first a shorter clone (HCV-G4 KM short, GenBank: AB795432.1), which contained 9,545 nucleotides with 341 nucleotides of the 5′UTR and 177 nucleotides of the 3′UTR, and this was frequently obtained for unknown reasons. We also obtained a longer clone by dividing the HCV genome into three fragments and the poly (U) sequences. We obtained a longer 3′UTR sequence than that of the HCV-G4 KM short clone, which contained 9,617 nucleotides. This longer clone possessed a 3′-UTR of 249 nucleotides (HCV-G4 KM long, GenBank: AB795432.2), because of a 71-nucleotide longer poly (U) stretch. The HCV-G4-KM long clone, but not the HCV-G4-KM short clone, could establish infection in human hepatoma HuH-7 cells. HCV RNAs carrying a nanoluciferase (NL) reporter were also constructed and higher replication activity was observed with G4-KM long-NL in vitro. Next, both short and long RNAs were intra-hepatically injected into humanized chimeric mice. Viral propagation was only observed for the chimeric mouse injected with the HCV-G4 KM long RNA in the sera after 21 days (1.64 × 106 copies/mL) and continued until 10 weeks post inoculation (wpi; 1.45–4.74 × 107 copies/mL). Moreover, sequencing of the HCV genome in mouse sera at 6 wpi revealed the sequence of the HCV-G4-KM long clone. Thus, the in vitro and in vivo results of this study indicate that the sequence of the HCV-G4-KM long RNA is that of an infectious clone.

Xanthomicrol suppresses human hepatocellular carcinoma cells migration and invasion ability via Μu-opioid receptor.

Xanthomicrol is one of the methoxylated flavones and a promising cancer chemopreventive agent, but its anti-migration and anti-invasion ability on human hepatocellular carcinoma (HCC) remains unknown. This study aims to explore Xanthomicrol's effects on migration and invasion ability of the human HCC Huh7 cell line. Viability of Huh7 cells was measured by cell counting kit-8 (CCK8) assay. Cell apoptosis was assayed with flow cytometry analysis. The ability of migration and invasion of Huh7 cells was then detected through Transwell assays. Epithelial-mesenchymal transition (EMT)-related proteins were also detected through Western blot. Xanthomicrol inhibits the migration and invasion of Huh7 cells. The overexpression of Μu-opioid receptor (MOR) increases Huh7 cells' proliferation and enhances migration and invasion ability, while xanthomicrol treatment decreases the expression of MOR. Moreover, xanthomicrol can reverse migration, invasion and EMT-related protein expression by overexpressed MOR. These results suggest that xanthomicrol is a potential MOR antagonist, and it possesses potent anti-migration and anti-invasion ability on Huh7 cells.

Tribbles pseudokinase 3 (TRIB3) contributes to the progression of hepatocellular carcinoma by activating the mitogen-activated protein kinase pathway.

BackgroundTribble pseudokinase 3 (TRIB3) plays a key role in regulating the malignancy of many tumors. This study examined its function in cancer cells and explored the potential mechanisms of action.MethodsThe expression of TRIB3 was examined in hepatocellular carcinomas (HCCs) using The Cancer Genome Atlas (TCGA) database. A TRIB3 lentivirus with a flag label was constructed and transfected into Huh7 and Hep3B human hepatoma cell lines to generate cells that stably overexpress TRIB3. A small interfering RNA (siRNA) was designed to knockdown TRIB3 mRNA in HepG2 and Huh7. Cell viability and cell colony formation assays were conducted. Flow cytometry was performed to assess the cell cycle in cells overexpressing TRIB3. Western blotting were performed to examine the expression of (Mitogen-activated protein kinase, MAPKK) (MEK), phosphorylated-MEK (p-MEK), extracellular signal-regulated kinase (ERK), and p-MEK in cells with TRIB3 knockdown. The correlation between TRIB3 and SMARCD3 was assessed using co-immunoprecipitation assays and immunofluorescence.ResultsTRIB3 was significantly overexpressed in advanced grade HCC tissues and was closely correlated with poor prognosis. TRIB3 overexpression promoted the cell growth and cell cycle but had little effect on migration capabilities in Huh7 and Hep3B cells. Conversely, knockdown of TRIB3 had slow down the cell growth in Huh7 and HepG2 cells detected by CCK8 and colony formation assay. The expression of MEK and ERK at both the protein and mRNA levels were downregulated when TRIB3 was knocked down. The protein expression of p-ERK and p-MEK were also downregulated upon TRIB3 silencing. SMARCD3 is a transcript factor that is belongs to the SWI/SNF complex and has been shown to regulate many genes. Indeed, co-immunoprecipitation assays demonstrated that TRIB3 interacts with SMARCD3 in the nucleus, suggesting that it may regulate TRIB3 in HCCs.ConclusionsThis study demonstrated that TRIB3 promotes the malignancy of HCC cells and its expression may be a potential diagnostic biomarker for HCC progression.

Insulin-induced genes INSIG1 and INSIG2 mediate oxysterol-dependent activation of the PERK–eIF2α–ATF4 axis

Insulin-induced genes (INSIGs) encode endoplasmic reticulum–resident proteins that regulate intracellular cholesterol metabolism. Oxysterols are oxygenated derivatives of cholesterol, some of which orchestrate lipid metabolism via interaction with INSIGs. Recently, it was reported that expression of activating transcription factor-4 (ATF4) was induced by certain oxysterols; the precise of mechanism is unclear. Herein, we show that INSIGs mediate ATF4 upregulation upon interaction with oxysterol. Oxysterols that possess a high affinity for INSIG, such as 27- and 25-hydroxycholesterol (25HC), markedly induced the increase of ATF4 protein when compared with other oxysterols. In addition, ATF4 upregulation by these oxysterols was attenuated in INSIG1/2-deficient Chinese hamster ovary cells and recovered by either INSIG1 or INSIG2 rescue. Mechanistic studies revealed that the binding of 25HC to INSIG is critical for increased ATF4 protein via activation of protein kinase RNA-activated–like ER kinase and eukaryotic translation initiation factor 2α. Knockout of INSIG1 or INSIG2 in human hepatoma Huh7 cells attenuated ATF4 protein upregulation, indicating that only one of the endogenous INSIGs, unlike overexpression of intrinsic INSIG1 or INSIG2, was insufficient for ATF4 induction. Furthermore, ATF4 proactively upregulated the cell death–inducible gene expression, such as Chop, Chac1, and Trb3, thereby markedly reducing cell viability with 25HC. These findings support a model whereby that INSIGs sense an increase in oxysterol in the endoplasmic reticulum and induce an increase of ATF4 protein via the protein kinase RNA-activated–like ER kinase–eukaryotic translation initiation factor 2α pathway, thereby promoting cell death.

Receptor Activity-Modifying Protein 2 (RAMP2) alters glucagon receptor trafficking in hepatocytes with functional effects on receptor signalling

ObjectivesReceptor Activity-Modifying Protein 2 (RAMP2) is a chaperone protein which allosterically binds to and interacts with the glucagon receptor (GCGR). The aims of this study were to investigate the effects of RAMP2 on GCGR trafficking and signalling in the liver, where glucagon (GCG) is important for carbohydrate and lipid metabolism. MethodsSubcellular localisation of GCGR in the presence and absence of RAMP2 was investigated using confocal microscopy, trafficking and radioligand binding assays in human embryonic kidney (HEK293T) and human hepatoma (Huh7) cells. Mouse embryonic fibroblasts (MEFs) lacking the Wiskott-Aldrich Syndrome protein and scar homologue (WASH) complex and the trafficking inhibitor monensin were used to investigate the effect of halted recycling of internalised proteins on GCGR subcellular localisation and signalling in the absence of RAMP2. NanoBiT complementation and cyclic AMP assays were used to study the functional effect of RAMP2 on the recruitment and activation of GCGR signalling mediators. Response to hepatic RAMP2 upregulation in lean and obese adult mice using a bespoke adeno-associated viral vector was also studied. ResultsGCGR is predominantly localised at the plasma membrane in the absence of RAMP2 and exhibits remarkably slow internalisation in response to agonist stimulation. Rapid intracellular accumulation of GCG-stimulated GCGR in cells lacking the WASH complex or in the presence of monensin indicates that activated GCGR undergoes continuous cycles of internalisation and recycling, despite apparent GCGR plasma membrane localisation up to 40 min post-stimulation. Co-expression of RAMP2 induces GCGR internalisation both basally and in response to agonist stimulation. The intracellular retention of GCGR in the presence of RAMP2 confers a bias away from β-arrestin-2 recruitment coupled with increased activation of Gαs proteins at endosomes. This is associated with increased short-term efficacy for glucagon-stimulated cAMP production, although long-term signalling is dampened by increased receptor lysosomal targeting for degradation. Despite these signalling effects, only a minor disturbance of carbohydrate metabolism was observed in mice with upregulated hepatic RAMP2. ConclusionsBy retaining GCGR intracellularly, RAMP2 alters the spatiotemporal pattern of GCGR signalling. Further exploration of the effects of RAMP2 on GCGR in vivo is warranted.