RNA helicase DEAD-box protein 5 alleviates nonalcoholic steatohepatitis progression via tethering TSC complex and suppressing mTORC1 signaling.

BACKGROUND AND AIMS: Nonalcoholic fatty liver disease and its progressive form, nonalcoholic steatohepatitis (NASH), are rapidly becoming the top causes of hepatocellular carcinoma (HCC). Currently, there are no approved therapies for the treatment of NASH. DEAD-box protein 5 (DDX5) plays important roles in different cellular processes. However, the precise role of DDX5 in NASH remains unclear. APPROACH AND RESULTS: DDX5 expression was downregulated in patients with NASH, mouse models with diet-induced NASH (high-fat diet [HFD], methionine- and choline-deficient diet, and choline-deficient HFD), mouse models with NASH-HCC (diethylnitrosamine with HFD), and palmitic acid-stimulated hepatocytes. Adeno-associated virus-mediated DDX5 overexpression ameliorates hepatic steatosis and inflammation, whereas its deletion worsens such pathology. The untargeted metabolomics analysis was carried out to investigate the mechanism of DDX5 in NASH and NASH-HCC, which suggested the regulatory effect of DDX5 on lipid metabolism. DDX5 inhibits mechanistic target of rapamycin complex 1 (mTORC1) activation by recruiting the tuberous sclerosis complex (TSC)1/2 complex to mTORC1, thus improving lipid metabolism and attenuating the NACHT-, leucine-rich-repeat (LRR)-, and pyrin domain (PYD)-containing protein 3  inflammasome activation. We further identified that the phytochemical compound hyperforcinol K directly interacted with DDX5 and prevented its ubiquitinated degradation mediated by ubiquitin ligase (E3) tripartite motif protein 5, thereby significantly reducing lipid accumulation and inflammation in a NASH mouse model. CONCLUSIONS: These findings provide mechanistic insight into the role of DDX5 in mTORC1 regulation and NASH progression, as well as suggest a number of targets and a promising lead compound for therapeutic interventions against NASH.

TKF, a mexicanolide-type limonoid derivative, suppressed hepatic stellate cells activation and liver fibrosis through inhibition of the YAP/Notch3 pathway.

BACKGROUND: Liver fibrosis is a common scarring response and may ultimately lead to liver cancer, unfortunately, there is currently no effective antifibrotic drug approved for human use. Limonoids exhibit a broad spectrum of biological activities; however, the potential role of limonoids against fibrosis is largely unknown. PURPOSE: This study investigates the antifibrotic activities and potential mechanisms of TKF (3-tigloyl-khasenegasin F), a natural mexicanolide-type limonoid derivative. STUDY DESIGN/METHODS: Two well-established mouse models (CCl4 challenge and bile duct ligation) were used to assess anti-fibrotic effects of TKF in vivo. Human hepatic stellate cell (HSC) line LX-2 and mouse primary hepatic stellate cells (pHSCs) also served as in vitro liver fibrosis models. RESULT: TKF administration significantly attenuated hepatic histopathological injury and collagen accumulation and suppressed fibrogenesis-associated gene expression including Col1a1, Acta2, and Timp1. In LX-2 cells and mouse pHSCs, TKF dose-dependently suppressed HSC activation and the expression levels of fibrogenic markers. Mechanistic studies showed that TKF inhibited Notch3-Hes1 and YAP signalings in vivo and in vitro. Furthermore, YAP inhibition or knockdown downregulated the Notch3 expression; however, Notch3 inhibition or knockdown did not affect the level of YAP in activated HSC. We revealed that TKF inhibited Notch3-Hes1 activation and downregulated hepatic fibrogenic gene expression via inhibiting YAP. CONCLUSION: The therapeutic benefit of TKF against liver fibrosis results from inhibition of YAP and Notch3-Hes1 pathways, indicating that TKF may be a novel therapeutic candidate for liver fibrosis.

Physalin B attenuates liver fibrosis via suppressing LAP2α-HDAC1-mediated deacetylation of the transcription factor GLI1 and hepatic stellate cell activation.

BACKGROUND AND PURPOSE: Liver fibrosis is one of the leading causes of morbidity and mortality worldwide but lacks any acceptable therapy. The transcription factor glioma-associated oncogene homologue 1 (GLI1) is a potentially important therapeutic target in liver fibrosis. This study investigates the anti-fibrotic activities and potential mechanisms of the phytochemical, physalin B. EXPERIMENTAL APPROACH: Two mouse models (CCl4 challenge and bile duct ligation) were used to assess antifibrotic effects of physalin B in vivo. Mouse primary hepatic stellate cells (pHSCs) and human HSC line LX-2 also served as in vitro liver fibrosis models. Liver fibrogenic genes, GLI1 and GLI1 downstream genes were examined using Western blot and quantitative real-time PCR (qRT-PCR). GLI1 acetylation and LAP2α-HDAC1 interaction were analysed by co-immunoprecipitation. KEY RESULTS: In vivo, physalin B administration attenuated hepatic histopathological injury and collagen accumulation and decreased expression of fibrogenic genes. Physalin B dose-dependently suppressed fibrotic marker expression in LX-2 cells and mouse pHSCs. Mechanistic studies showed that physalin B inhibited GLI activity by non-canonical Hedgehog signalling. Physalin B blocked formation of lamina-associated polypeptide 2α (LAP2α)/histone deacetylase 1 (HDAC1) complexes, thus inhibiting HDAC1-mediated GLI1 deacetylation. Physalin B up-regulated acetylation of GLI1, down-regulated expression of GLI1 and subsequently inhibited HSC activation. CONCLUSION AND IMPLICATIONS: Physalin B exerted potent antifibrotic effects in vitro and in vivo by disrupting LAP2α/HDAC1 complexes, increasing GLI1 acetylation and inactivating GLI1. This indicates that the phytochemical physalin B may be a potential therapeutic candidate for the treatment of liver fibrosis.

Limb expression 1-like (LIX1L) protein promotes cholestatic liver injury by regulating bile acid metabolism.

BACKGROUND & AIMS: Cholestatic liver diseases comprise a variety of disorders of bile formation and/or flow which generally result in progressive hepatobiliary injury. Regulation of bile acid (BA) synthesis and homeostasis is a promising strategy for the treatment of cholestatic liver disease. Limb expression 1-like protein (LIX1L) plays an important role in post-transcriptional gene regulation, yet its role in cholestatic liver injury remains unclear. METHODS: LIX1L expression was studied in patients with primary sclerosing cholangitis (PSC) or primary biliary cholangitis (PBC), and 3 murine models of cholestasis (bile duct ligation [BDL], Mdr2 knockout [Mdr2-/-], and cholic acid [CA] feeding). Lix1l knockout mice were employed to investigate the function of LIX1L in cholestatic liver diseases. Chromatin immunoprecipitation assays were performed to determine whether Egr-1 bound to the Lix1l promoter. MiRNA expression profiling was analyzed by microarray. An adeno-associated virus (AAV)-mediated hepatic delivery system was used to identify the function of miR-191-3p in vivo. RESULTS: LIX1L expression was increased in the livers of patients with PSC and PBC, and in the 3 murine models, as well as in BA-stimulated primary mouse hepatocytes. BA-induced Lix1l upregulation was dependent on Egr-1, which served as a transcriptional activator. LIX1L deficiency attenuated cholestatic liver injury in BDL and Mdr2-/- mice. MiR-191-3p was the most reduced miRNA in livers of WT-BDL mice, while it was restored in Lix1l-/--BDL mice. MiR-191-3p targets and downregulates Lrh-1, thereby inhibiting Cyp7a1 and Cyp8b1 expression. AAV-mediated hepatic delivery of miR-191-3p significantly attenuated cholestatic liver injury in Mdr2-/- mice. CONCLUSIONS: LIX1L deficiency alleviates cholestatic liver injury by inhibiting BA synthesis. LIX1L functions as a nexus linking BA/Egr-1 and miR-191-3p/LRH-1 signaling. LIX1L and miR-191-3p may be promising targets for the treatment of BA-associated hepatobiliary diseases. LAY SUMMARY: Bile acid homeostasis can be impaired in cholestatic liver diseases. Our study identified a novel mechanism of positive feedback regulation in cholestasis. LIX1L and miR-191-3p represent potential therapeutic targets for cholestatic liver diseases.

Physalin B ameliorates nonalcoholic steatohepatitis by stimulating autophagy and NRF2 activation mediated improvement in oxidative stress.

Non-alcoholic steatohepatitis (NASH) is the progressive stage of non-alcoholic fatty liver disease that may ultimately lead to cirrhosis and liver cancer, and there are few therapeutic options for its treatment. Physalin B (PB), a withanolide isolated from Physalis species (Solanaceae), exhibits a broad spectrum of biological activities, however, the potential role of PB in NASH has not been evaluated. The present study investigated the protective effects of PB against NASH and further elucidated the mechanisms of PB in hepatic autophagy and oxidative stress in vitro and in vivo. We conducted a series of experiments using methionine-choline deficient (MCD) diet induced NASH mice and cultured L02 cells. Serum markers of liver injury, morphology, and the histology of liver tissues were investigated. Western blot assays and quantitative real-time PCR were used to investigate the hepatoprotective effect of PB. PB significantly ameliorated hepatic injury, including hepatic index, transaminase activities, histology, and inflammation in MCD-induced mice. Moreover, PB markedly increased the expression of P62 and the ratio of LC3Ⅱ/Ⅰ in vitro and in vivo. Furthermore, PB promoted the interaction between endogenous KEAP1 and P62, reduced the interaction between KEAP1 and NRF2, activated the nuclear translocation of NRF2 and NRF2 target gene expression, and ultimately attenuated oxidative stress. In addition, knockdown of P62 blocked PB-mediated activation of NRF2 in L02 cells. These results clearly indicated that PB ameliorated NASH by stimulating autophagy and P62-KEAP1-NRF2 antioxidative signaling, suggesting that PB is expected to become a novel therapeutic drug for NASH.

Pathogenesis of NASH and Promising Natural Products.

Nonalcoholic steatohepatitis (NASH) is a common clinical condition that can lead to advanced liver diseases. The mechanism of the diaease progression, which is lacking effective therapy, remains obsure. Therefore, there is a need to understand the pathogenic mechanisms responsible for disease development and progression in order to develop innovative therapies. To accomplish this goal, experimental animal models that recapitulate the human disease are necessary. Currently, an increasing number of studies have focused on natural constituents from medicinal plants which have been emerged as a new hope for NASH. This review summarized the pathogenesis of NASH, animal models commonly used, and the promising targets for therapeutics. We also reviewed the natural constituents as potential NASH therapeutic agents.

MicroRNA and long noncoding RNA involvement in gout and prospects for treatment.

MicroRNAs (miRNAs) and long noncoding RNAs (lncRNAs) are both types of noncoding RNA. They have been demonstrated to be involved in the regulation of various human inflammatory diseases and can be used as biomarkers for disease diagnosis and prognosis, and even be developed into new drugs. Gout is an arthritic disease caused by the deposition of monosodium urate crystal (MSU) in the joints, which can lead to acute inflammation and damage adjacent tissue. Recent studies have shown that miRNAs and lncRNAs mediate the progress of gout. Based on the pathogenesis of gout, including hyperuricemia, MSU deposition, acute gouty arthritis and gouty bone erosion, this paper reviewed the role of miRNAs and lncRNAs in the processes and the possible therapeutic targets of miRNAs and lncRNAs in gout.