GTPBP8 mitigates nonalcoholic steatohepatitis (NASH) by depressing hepatic oxidative stress and mitochondrial dysfunction via PGC-1α signaling.

Nonalcoholic steatohepatitis (NASH) is emerging as a major cause of liver transplantation and hepatocellular carcinoma (HCC). Regrettably, its pathological mechanisms are still not fully comprehended. GTP-binding protein 8 (GTPBP8), belonging to the GTP-binding protein superfamily, assumes a crucial role in RNA metabolism, cell proliferation, differentiation, and signal transduction. Its aberrant expression is associated with oxidative stress and mitochondrial dysfunctions. Nevertheless, its specific functions and mechanisms of action, particularly in NASH, remain elusive. In our current study, we initially discovered that human hepatocytes L02 displayed evident mitochondrial respiratory anomaly, mitochondrial damage, and dysfunction upon treatment with palmitic acids and oleic acids (PO), accompanied by significantly reduced GTPBP8 expression levels through RNA-Seq, RT-qPCR, western blotting, and immunofluorescence assays. We then demonstrated that GTPBP8 overexpression mediated by adenovirus vector (Ad-GTPBP8) markedly attenuate lipid accumulation, inflammatory response, and mitochondrial impair and dysfunction in hepatocytes stimulated by PO. Conversely, adenovirus vector-mediated GTPBP8 knockdown (Ad-shGTPBP8) significantly accelerated lipid deposition, inflammation and mitochondrial damage in PO-treated hepatocytes in vitro. Furthermore, we constructed an in vivo NASH murine model by giving a 16-week high fat high cholesterol diet (HFHC) diet to hepatocyte specific GTPBP8-knockout (GTPBP8HKO) mice. We firstly found that HFHC feeding led to metabolic disorder in mice, including high body weight, blood glucose and insulin levels, and liver dysfunctions, which were accelerated in these NASH mice with GTPBP8 deficiency in hepatocytes. Consistently, GTPBP8HKO remarkably exacerbated the progression of NASH phenotypes induced by HFHC, as proved by the anabatic lipid accumulation, inflammation, fibrosis and reactive oxygen species (ROS) production in liver tissues, which could be largely attributed to the severe mitochondrial damage and dysfunction. Mechanistically, we further identified that GTPBP8 interacted with peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) in hepatocytes. Importantly, the hepaprotective effects of GTPBP8 against mitochondrial dysfunction, oxidative stress and inflammation was largely dependent on PGC-1α expression. Collectively, GTPBP8 may exert a protective role in the progression of NASH, and targeting the GTPBP8/PGC-1α axis may represent a potential strategy for NASH treatment by improving mitochondrial functions.

Meng D ，Chang M ，Dai X ，Kuang Q ，Wang G ... -  《-》

Vine tea (Ampelopsis grossedentata) ameliorates chronic alcohol-induced hepatic steatosis, oxidative stress, and inflammation via YTHDF2/PGC-1α/SIRT3 axis.

For over a millennium, the leaves of Ampelopsis grossedentata (Hand.-Mazz.) W. T. Wang, commonly known as vine tea, have been revered as a popular tea and traditional herbal remedy, possessing antioxidant, anti-inflammatory, hepatoprotective, and antiviral properties. In recent years, the incidence of alcohol-related liver injury has been on the rise, imposing a significant public health burden worldwide. Previous studies have indicated that extracts of vine tea (AGE) can ameliorate alcoholic liver disease (ALD), yet the pharmacological mechanisms underlying this effect remain poorly understood. In this study, we first employed UPLC-Q-TOF-MS to analyze the chemical constituents of AGE. Subsequently, an ALD model was established in mice fed with Lieber-DeCarli diet, and the hepatoprotective benefits of AGE were assessed by measuring biochemical indicators and hepatic pathological changes. Moreover, a suite of bioinformatics tools, including transcriptomics, weighted gene co-expression network analysis, and single-cell data mining, were utilized to reveal that the YTHDF2/PGC-1α/SIRT3 signaling axis may be the potential mechanism by which AGE exerts its anti-ALD effects. Additionally, Western blotting and immunofluorescence staining techniques were employed to further substantiate the aforementioned mechanism. Our findings demonstrate that administration of vine tea significantly alleviated chronic ethanol-induced hepatic lipid accumulation, oxidative stress, and inflammation. Notably, knockdown of YTHDF2 partially protected the liver from ethanol-induced injury. Mechanistically, bioinformatics analysis and in vitro and in vivo experiments identified YTHDF2 as a key pharmacological target of AGE in treating ALD, acting through the downstream PGC-1α/SIRT3 pathway. In summary, in this study, we provide the first evidence that AGE mitigates ethanol-induced liver injury by inhibiting YTHDF2 and enhancing the expression of PGC-1α and SIRT3. Vine tea, as a tea food with unique medicinal value, shows significant potential and value in the treatment of ALD.

Luo Q ，Qiu J ，Chen M ，Yang N ，Li X ，Huang S ，Ma Q ，Li Z ，Lou D ，Du Y ，Chen L ，Shen Q ，Chen F ，Li C ，Qiu P ... -  《-》

Cinnabarinic acid protects against metabolic dysfunction-associated steatohepatitis by activating aryl hydrocarbon receptor-dependent AMPK signaling.

Patil NY ，Rus I ，Ampadu F ，Abu Shukair HM ，Bonvicino S ，Brush RS ，Eaton E ，Agbaga MP ，Oh TG ，Friedman JE ，Joshi AD ... -  《-》

Hinokitiol ameliorates MASH in mice by therapeutic targeting of hepatic Nrf2 and inhibiting hepatocyte ferroptosis.

Metabolic dysfunction-associated steatohepatitis (MASH), an advanced stage of metabolic dysfunction-associated steatotic liver disease (MASLD), still lacks approved effective clinical drugs. Ferroptosis, a form of regulated cell death driven by excessive iron accumulation and uncontrollable lipid peroxidation, has been proven to be a trigger of inflammation and initiation of steatohepatitis. The pathogenic interplay is modulated by oxidative stress, while the Nrf2-mediated antioxidant response plays a regulatory role in ferroptosis. Phytochemical hinokitiol (Hino) has demonstrated positive efficacy in hepatocellular carcinoma (HCC) in the reported work, but it remains unknown whether its therapeutic effect attributes to delaying the progress of steatohepatitis to HCC. This work aimed to systemically investigate the significance of ferroptosis in the pathogenesis of MASH and to demonstrate that Hino, a bioactive monoterpene compound, attenuates the primary pathological characteristics of MASH via promotion of Nrf2/GPX4 signaling. In this work, a MASH model was established using the high-fat/high-cholesterol (HFHC) diet-fed in vivo and palmitic acid/oleic acid (PO)-stimulated hepatocytes in vitro. Biochemical indexes, pathological analysis, western blot, PCR assay, energy metabolic phenotype, molecular docking, and confirmatory assays were performed comprehensively to reveal the key link between the Nrf2/GPX4 axis and the treatment of MASH. Under MASH conditions with increased oxidative stress, we show that Nrf2 was remarkable downregulated in HFHC diet-fed mice and PO-managed hepatocytes. Mechanistically, hepatic upregulation of Nrf2 through phytochemical Hino supplementation inhibited ferroptosis, enhanced lipid metabolism, and thereby alleviated hepatic steatosis, inflammation, and fibrosis. Conversely, silencing Nrf2 in hepatocytes further promoted the accumulation of key markers of ferroptosis and aggravated MASH phenotypes. Increased ferroptosis promoted steatosis which further drove inflammation and hepatic fibrosis. Our results suggested the significance of Nrf2 in ameliorating MASH, which was regulated through Hino. Thus, targeted inhibition of ferroptosis through Hino administration is a feasible and effective approach for treating MASH.

Yin X ，Liu Z ，Li C ，Wang J ... -  《-》

Inhibition of ZFP281/ZNF281-RIPK1/RIPK3/MLKL signaling in hepatocytes by pterostilbene relieves hepatic lipometabolic disorder and inflammation in non-alcoholic steatohepatitis.

Non-alcoholic steatohepatitis (NASH) is the most common cause of chronic liver diseases with its pathophysiological mechanism poorly understood. In this work, serological, histological, molecular biological, biochemical, and immunological methods were applied to explore the pathological significance and action of zinc finger protein 281 (ZFP281 in mouse, ZNF281 in human) and targeted strategies. We reported that ZFP281/ZNF281 abundance in hepatocytes was positively correlated with the progression of NASH. Hepatocyte-specific knockdown of Zfp281 prevented mice from NASH diet-induced liver injury, steatosis, inflammation, and fibrosis. Consistently, the metabolic syndromes in NASH mice, characterized by obesity, hyperglycemia, insulin resistance, and hyperlipidemia, were also relieved by hepatocyte-specific Zfp281 deficiency. Mechanistically, incremental ZNF281 led to the upregulation of proinflammatory signaling, receptor-interacting protein kinase 1 (RIPK1)/RIPK3/mixed lineage kinase domain like pseudokinase (MLKL) axis in hepatocytes bearing free fatty acid stress. Activated MLKL translocated to the mitochondrial membrane, disrupting mitochondrial fatty acid β-oxidation and facilitating lipid accumulation in hepatocytes exposed to free fatty acid stimulation; also, MLKL in activated form orientated to the plasma membrane, triggering the lytic death mode in hepatocytes and launching hepatocellular proinflammatory responses. Moreover, we screened a ZFP281 inhibitor, pterostilbene, and demonstrated that pterostilbene, by inhibiting ZFP281 elevation in NASH livers, reduced hepatocyte injury, steatosis, inflammatory responses and fibrogenesis. In conclusion, this work proposes that induction of ZFP281/ZNF281-RIPK1/RIPK3/MLKL signaling disrupts fatty acid metabolism, promoting lipid accumulation, and triggers proinflammatory cell death, accelerating hepatic necroinflammation. Our work identifies ZFP281/ZNF281 as a promising target as well as pterostilbene as a potential strategy for NASH managing.

Lu C ，Zhang Y ，Miao J ，Wei W ，Wang Y ，Han Y ，Li Y ，Tong Y ，Wang T ，Bao X ... -  《-》