Impaired TFEB-Mediated Lysosome Biogenesis and Autophagy Promote Chronic Ethanol-Induced Liver Injury and Steatosis in Mice

TFEB activator tanshinone IIA and derivatives derived from Salvia miltiorrhiza Bge. Attenuate hepatic steatosis and insulin resistance

ETHNOPHARMACOLOGICAL RELEVANCE

Salvia miltiorrhiza Bge. (SMB) is an herbal medicine extensively used for improving metabolic disorders, including Nonalcoholic fatty liver disease (NAFLD). However, the potential material basis and working mechanism still remained to be elucidated.

AIM OF THE STUDY

To find potential ingredients for therapy of NAFLD by high content screening and further verify the efficacy on restoring hepatic steatosis and insulin resistance, and clarify the potential working mechanism.

MATERIALS AND METHODS

The mouse transcription factor EB (Tfeb) in preadipocytes was knocked out by CRISPR-Cas9 gene editing. High content screening of TFEB nuclear translocation was performed to identify TFEB activators. The effect of candidate compounds on reducing lipid accumulation was evaluated using Caenorhabditis elegans (C. elegans). Then the role of Salvia miltiorrhiza extract (SMB) containing Tanshinone IIA and the derivatives were further investigated on high-fat diet (HFD) fed mice. RNA-seq was performed to explore potential molecular mechanism of SMB. Finally, the gut microbiota diversity was evaluated using 16S rRNA sequencing to investigate the protective role of SMB on regulating gut microbiota homeostasis.

RESULTS

Knockout of Tfeb led to excessive lipid accumulation in adipocytes while expression of TFEB homolog HLH-30 in C. elegans (MAH240) attenuated lipid deposition. Screening of TFEB activators identified multiple candidates from Salvia miltiorrhiza, all of them markedly induced lysosome biogenesis in HepG2 cells. One of the candidate compounds Tanshinone IIA significantly decreased lipid droplet deposition in HFD fed C. elegans. Administration of SMB on C57BL/6J mice via gastric irrigation at the dose of 15 g/kg/d markedly alleviated hepatic steatosis, restored serum lipid profile, and glucose tolerance. RNA-seq showed that gene expression profile was altered and the genes related to lipid metabolism were restored. The disordered microbiome was remodeled by SMB, Firmicutes and Actinobacteriotawere notably reduced, Bacteroidota and Verrucomicrobiota were significantly increased.

CONCLUSION

Taken together, the observations presented here help address the question concerning what were the main active ingredients in SMB for alleviating NAFLD, and established that targeting TFEB was key molecular basis for the efficacy of SMB.

Alcohol promotes hepatocyte injury via ER stress sensor XBP1s mediated regulation of autophagy and lysosomal activity

OBJECTIVE

Endoplasmic reticulum stress (ERS) plays an important role in the development of Alcoholic liver injury (ALI), but the exact mechanism needs further exploration. This study aims to investigate the role of ERS-XBP1s in ALI, and providing new target for the treatment of liver injury.

METHOD

The ALI model was constructed using the NIAAA method and was validated by several methods. ERS was detected using western-blot, RT-PCR and immunohistochemistry. Apoptosis was measured by TUNEL staining, Hoechst staining, western-blot and Annexin V-FITC. Lysosomal function and autophagy were measured by Lyso-Tracker Green probe, western-blot and immunofluorescence, respectively.

RESULTS

The ALI model was successfully constructed as demonstrated by increased liver steatosis, inflammation and oxidative stress, and higher levels of serum ALT, AST and TG. Alcohol significantly increased the expression of ERS-related molecules, such as PERK, IRE1α, GRP78 and XBP1s, and promoted the nuclear translocation of XBP1s. Moreover, alcohol significantly increased apoptosis and inhibition of XBP1s could reverse this effect in vivo and in vitro. Interestingly, we found that alcohol significantly elevated hepatocyte LC3-II/I levels and concomitantly accumulation of P62, and this phenomenon was reversed by inhibiting XBP1s both in vivo and in vitro. Mechanistically, we found that alcohol activation of ER stress sensor XBP1s which promoted liver injury via inhibiting lysosomal function and autophagy activity in hepatocytes, whereas inhibition of XBP1s reduces hepatocyte apoptosis by restoring lysosomal activity and activating of autophagy.

CONCLUSION

Alcohol promotes hepatocytes injury via ER stress sensor XBP1s mediated inhibition of autophagy. Therefore, inhibition of XBP1 may protect the liver from alcohol-induced damage.

SMURF1 mediates damaged lysosomal homeostasis by ubiquitinating PPP3CB to promote the activation of TFEB

The calcium-activated phosphatase PPP3/calcineurin dephosphorylates TFEB (transcription factor EB) to trigger its nuclear translocation and the activation of macroautophagic/autophagic targets. However, the detailed molecular mechanism regulating TFEB activation remains poorly understood. Here, we highlighted the importance of SMURF1 (SMAD specific E3 ubiquitin protein ligase 1) in the activation of TFEB for lysosomal homeostasis. SMURF1 deficiency prevents the calcium-triggered ubiquitination of the catalytic subunit of PPP3/calcineurin in a manner consistent with defective autophagic degradation of damaged lysosomes. Mechanically, PPP3CB/CNA2 plays a bridging role in the recruitment of SMURF1 by LGALS3 (galectin 3) upon lysosome damage. Importantly, PPP3CB increases the dissociation of the N-terminal tail (NT) and C-terminal carbohydrate-recognition domain (CRD) of LGALS3, which may promote the formation of open conformers in a PPP3CB dephosphorylation activity-dependent manner. In addition, PPP3CB is ubiquitinated at lysine 146 by the recruited SMURF1 in response to intracellular calcium stimulation. The K63-linked ubiquitination of PPP3CB enhances the recruitment of TFEB. Moreover, TFEB directly interacts with both PPP3CB and the regulatory subunit PPP3R1 which facilitate the conformational correction of TFEB for its activation for the transcription of TFEB-targeted genes. Altogether, our results highlighted a critical mechanism for the regulation of PPP3/calcineurin activity via its ubiquitin ligase SMURF1 in response to lysosomal membrane damage, which may account for a potential target for the treatment of stress-related diseases.

Dioscin improves fatty liver hemorrhagic syndrome by promoting ERα-AMPK mediated mitophagy in laying hens

BACKGROUND

Mitochondria play a crucial role in upholding metabolic homeostasis. Mitochondrial damage closely associated with the pathogenesis of fatty liver hemorrhagic syndrome (FLHS), while mitophagy being among the most effective methods for eliminating the damaged mitochondria. Dioscin, a natural extract, can activate autophagy; however, its effects on FLHS regarding mitophagy regulation remain unelucidated.

PURPOSE

We explored the impact of dioscin on FLHS induced by a high-energy and low-protein (HELP) diet in laying hens, mainly focused the protective effects of dioscin on mitochondrial injury.

METHOD

To investigate the impact of dioscin on fatty liver syndrome in laying hens, we first induced the condition by feeding them a high-energy and low-protein diet. Then, we assessed lipid metabolism-related markers using oil red staining and a commercial detection kit. In addition, the role of dioscin on fatty liver syndrome in laying hens was confirmed by assessing the activation of hepatocyte fat deposition and hepatocyte apoptosis; and the mechanism of dioscin in FLHS was investigated through LMH cell experiment in vitro. Furthermore, CETSA and molecular docking were conducted for additional confirmation.

RESULT

The results showed that dioscin alleviated mitochondrial damage, relieved the excessive deposition of hepatic lipid droplets and oxidative stress induced by HELP diet in laying hens. Furthermore, dioscin regulated the mitophagy by activating the estrogen receptor α (ERα)/adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling pathway, thus mitigating mitochondria injury and apoptosis in hepatocytes. In addition, we found that dioscin promoted the translocation of nuclear transcription factor into nucleus by activating ERα-AMPK signaling, facilitating autophagic flux in the liver of laying hens and LMH cells. Furthermore, cells pretreated with the lysosomal acidification inhibitor bafilomycin A1 blocked the inhibitory effect of dioscin on the apoptosis induced by palmitic acid (PA)-stimulation in LMH cells, suggesting that dioscin reduces PA-induced apoptosis by activating mitophagy. Moreover, dioscin-induced lysosomal acidification and mitochondrial biogenesis were reversed in PA-induced LMH cells pretreated with ERα-specific inhibitor methylpiperidino pyrazole.

CONCLUSION

This study firstly demonstrated that dioscin alleviates fatty liver syndrome induced by HELP diet in laying hens. The findings from this study illustrated that dioscin plays a significant role in reducing mitochondrial damage and apoptosis, and these beneficial effects mainly achieve through promotion of ERα-AMPK signaling, which mediates autophagy within the liver of laying hens fed a HELP-diets. These findings provide a theoretical basis for considering dioscin as a possible treatment option for mitigating FLHS in egg-laying hens.

Lysosomal TFEB-TRPML1 Axis in Astrocytes Modulates Depressive-like Behaviors

Lysosomes are important cellular structures for human health as centers for recycling, signaling, metabolism and stress adaptation. However, the potential role of lysosomes in stress-related emotions has long been overlooked. Here, it is found that lysosomal morphology in astrocytes is altered in the medial prefrontal cortex (mPFC) of susceptible mice after chronic social defeat stress. A screen of lysosome-related genes revealed that the expression of the mucolipin 1 gene (Mcoln1; protein: mucolipin TRP channel 1) is decreased in susceptible mice and depressed patients. Astrocyte-specific knockout of mucolipin TRP channel 1 (TRPML1) induced depressive-like behaviors by inhibiting lysosomal exocytosis-mediated adenosine 5'-triphosphate (ATP) release. Furthermore, this stress response of astrocytic lysosomes is mediated by the transcription factor EB (TFEB), and overexpression of TRPML1 rescued depressive-like behaviors induced by astrocyte-specific knockout of TFEB. Collectively, these findings reveal a lysosomal stress-sensing signaling pathway contributing to the development of depression and identify the lysosome as a potential target organelle for antidepressants.

HIF-2α drives hepatic Kupffer cell death and proinflammatory recruited macrophage activation in nonalcoholic steatohepatitis

Proinflammatory hepatic macrophage activation plays a key role in the development of nonalcoholic steatohepatitis (NASH). This involves increased embryonic hepatic Kupffer cell (KC) death, facilitating the replacement of KCs with bone marrow-derived recruited hepatic macrophages (RHMs) that highly express proinflammatory genes. Moreover, phago/efferocytic activity of KCs is diminished in NASH, enhancing liver inflammation. However, the molecular mechanisms underlying these changes in KCs are not known. Here, we show that hypoxia-inducible factor 2α (HIF-2α) mediates NASH-associated decreased KC growth and efferocytosis by enhancing lysosomal stress. At the molecular level, HIF-2α stimulated mammalian target of rapamycin (mTOR)- and extracellular signal-regulated kinase-dependent inhibitory transcription factor EB (TFEB) phosphorylation, leading to decreased lysosomal and phagocytic gene expression. With increased metabolic stress and phago/efferocytic burden in NASH, these changes were sufficient to increase lysosomal stress, causing decreased efferocytosis and lysosomal cell death. Of interest, HIF-2α-dependent TFEB regulation only occurred in KCs but not RHMs. Instead, in RHMs, HIF-2α promoted mitochondrial reactive oxygen species production and proinflammatory activation by increasing ANT2 expression and mitochondrial permeability transition. Consequently, myeloid lineage-specific or KC-specific HIF-2α depletion or the inhibition of mTOR-dependent TFEB inhibition using antisense oligonucleotide treatment protected against the development of NASH in mice. Moreover, treatment with an HIF-2α-specific inhibitor reduced inflammatory and fibrogenic gene expression in human liver spheroids cultured under a NASH-like condition. Together, our results suggest that macrophage subtype-specific effects of HIF-2α collectively contribute to the proinflammatory activation of liver macrophages, leading to the development of NASH.

Tetrahydrocurcumin ameliorates hepatic steatosis by restoring hepatocytes lipophagy through mTORC1-TFEB pathway in nonalcoholic steatohepatitis

PURPOSE

To investigate the therapeutic effect and underlying mechanism of tetrahydrocurcumin (THC) on nonalcoholic steatohepatitis (NASH) induced by high-fat diet (HFD).

METHODS

NASH rat model was established through long-term feeding HFD, and the steatosis cell model was stimulated via palmitate acid (PA). The therapeutic effect of THC was evaluated in terms of liver function, lipid metabolism, liver pathophysiology, inflammation and oxidative stress in vivo, and lipid accumulation in vitro. The alteration in lipophagy was identified by using western blot and immunofluorescence. mTORC1-TFEB signaling pathway was measured by qRT-PCR, western blot and protein-ligand docking. In addition, chloroquine and MHY1485 were further introduced to validate the effect of THC on lipophagy and mTORC1-TFEB signaling pathway, respectively.

RESULTS

THC effectively improved hepatic steatosis, inflammation and oxidative stress in NASH rats, and reduced lipid accumulation in steatosis L02 cells and Hep G2 cells. THC promoted lipophagy with increasing LC3B-II as well as decreasing P62 expression via lysosomal biogenesis upregulation, which was greatly weakened after chloroquine intervention. mTORC1-TFEB is a critical pathway for regulating lysosome in autophagy, THC treatment induced TFEB nucleus translocation via inhibiting mTORC1 to upregulate lysosomal biogenesis. However, these effects were partly eliminated by mTORC1 activator MHY1485.

CONCLUSION

THC restored lipophagy to reduce lipid accumulation by regulating mTORC1-TFEB pathway in NASH rats and steatosis hepatocytes. These findings suggested that THC represents a therapeutic candidate for NASH treatment.

Targeting Autophagy for Acetaminophen-Induced Liver Injury: An Update

Acetaminophen (APAP) overdose can induce hepatocyte necrosis and acute liver failure in experimental rodents and humans. APAP is mainly metabolized via hepatic cytochrome P450 enzymes to generate the highly reactive metabolite N-acetyl-p-benzoquinone imine (NAPQI), which forms acetaminophen protein adducts (APAP-adducts) and damages mitochondria, triggering necrosis. APAP-adducts and damaged mitochondria can be selectively removed by autophagy. Increasing evidence implies that the activation of autophagy may be beneficial for APAP-induced liver injury (AILI). In this minireview, we briefly summarize recent progress on autophagy, in particular, the pharmacological targeting of SQSTM1/p62 and TFEB in AILI.

Cyanidin-3-O-glucoside alleviates ethanol-induced liver injury by promoting mitophagy in a Gao-binge mouse model of alcohol-associated liver disease

BACKGROUND

Alcohol-associated liver disease (ALD) is a leading cause of liver disease-related deaths worldwide. Unfortunately, approved medications for the treatment of this condition are quite limited. One promising candidate is the anthocyanin, Cyanidin-3-O-glucoside (C3G), which has been reported to protect mice against hepatic lipid accumulation, as well as fibrosis in different animal models. However, the specific effects and mechanisms of C3G on ALD remain to be investigated.

EXPERIMENTAL APPROACH

In this report, a Gao-binge mouse model of ALD was used to investigate the effects of C3G on ethanol-induced liver injury. The mechanisms of these C3G effects were assessed using AML12 hepatocytes.

RESULTS

C3G administration ameliorated ethanol-induced liver injury by suppressing hepatic oxidative stress, as well as through reducing hepatic lipid accumulation and inflammation. Mechanistically, C3G activated the AMPK pathway and enhanced mitophagy to eliminate damaged mitochondria, thus reducing mitochondria-derived reactive oxidative species in ethanol-challenged hepatocytes.

CONCLUSIONS

The results of this study indicate that mitophagy plays a potentially important role underlying the hepatoprotective action of C3G, as demonstrated in a Gao-binge mouse model of ALD. Accordingly, C3G may serve as a promising, new therapeutic drug candidate for use in ALD.

Effects of elafibranor on liver fibrosis and gut barrier function in a mouse model of alcohol-associated liver disease

BACKGROUND

Alcohol-associated liver disease (ALD) is a leading cause of liver-related morbidity and mortality, but there are no therapeutic targets and modalities to prevent ALD-related liver fibrosis. Peroxisome proliferator activated receptor (PPAR) α and δ play a key role in lipid metabolism and intestinal barrier homeostasis, which are major contributors to the pathological progression of ALD. Meanwhile, elafibranor (EFN), which is a dual PPARα and PPARδ agonist, has reached a phase III clinical trial for the treatment of metabolic dysfunction-associated steatotic liver disease and primary biliary cholangitis. However, the benefits of EFN for ALD treatment is unknown.

AIM

To evaluate the inhibitory effects of EFN on liver fibrosis and gut-intestinal barrier dysfunction in an ALD mouse model.

METHODS

ALD-related liver fibrosis was induced in female C57BL/6J mice by feeding a 2.5% ethanol (EtOH)-containing Lieber-DeCarli liquid diet and intraperitoneally injecting carbon tetrachloride thrice weekly (1 mL/kg) for 8 weeks. EFN (3 and 10 mg/kg/day) was orally administered during the experimental period. Histological and molecular analyses were performed to assess the effect of EFN on steatohepatitis, fibrosis, and intestinal barrier integrity. The EFN effects on HepG2 lipotoxicity and Caco-2 barrier function were evaluated by cell-based assays.

RESULTS

The hepatic steatosis, apoptosis, and fibrosis in the ALD mice model were significantly attenuated by EFN treatment. EFN promoted lipolysis and β-oxidation and enhanced autophagic and antioxidant capacities in EtOH-stimulated HepG2 cells, primarily through PPARα activation. Moreover, EFN inhibited the Kupffer cell-mediated inflammatory response, with blunted hepatic exposure to lipopolysaccharide (LPS) and toll like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) signaling. EFN improved intestinal hyperpermeability by restoring tight junction proteins and autophagy and by inhibiting apoptosis and proinflammatory responses. The protective effect on intestinal barrier function in the EtOH-stimulated Caco-2 cells was predominantly mediated by PPARδ activation.

CONCLUSION

EFN reduced ALD-related fibrosis by inhibiting lipid accumulation and apoptosis, enhancing hepatocyte autophagic and antioxidant capacities, and suppressing LPS/TLR4/NF-κB-mediated inflammatory responses by restoring intestinal barrier function.

Programmed cell death, from liver Ischemia-Reperfusion injury perspective: An overview

Liver ischemia-reperfusion injury (LIRI) commonly occurs in liver resection, liver transplantation, shock, and other hemorrhagic conditions, resulting in profound local and systemic effects via associated inflammatory responses and hepatic cell death. Hepatocyte death is a significant component of LIRI and its mechanism was previously thought to be limited to apoptosis and necrosis. With the discovery of novel types of programmed cell death (PCD), necroptosis, ferroptosis, pyroptosis, autophagy, NETosis, and parthanatos have been shown to be involved in LIRI. Understanding the mechanisms underlying cell death following LIRI is indispensable to mitigating the widespread effects of LIRI. Here, we review the roles of different PCD and discuss potential therapy in LIRI.

New advances in drug development for metabolic dysfunction-associated diseases and alcohol-associated liver disease

Metabolic disorders are currently threatening public health worldwide. Discovering new targets and developing promising drugs will reduce the global metabolic-related disease burden. Metabolic disorders primarily consist of lipid and glucose metabolic disorders. Specifically, metabolic dysfunction-associated steatosis liver disease (MASLD) and alcohol-associated liver disease (ALD) are two representative lipid metabolism disorders, while diabetes mellitus is a typical glucose metabolism disorder. In this review, we aimed to summarize the new drug candidates with promising efficacy identified in clinical trials for these diseases. These drug candidates may provide alternatives for patients with metabolic disorders and advance the progress of drug discovery for the large disease burden.

The role of gut microbiota, exosomes, and their interaction in the pathogenesis of ALD

BACKGROUND

The liver disorders caused by alcohol abuse are termed alcoholic-related liver disease (ALD), including alcoholic steatosis, alcoholic steatohepatitis alcoholic hepatitis, and alcoholic cirrhosis, posing a significant threat to human health. Currently, ALD pathogenesis has not been completely clarified, which is likely to be related to the direct damage caused by alcohol and its metabolic products, oxidative stress, gut dysbiosis, and exosomes.

AIMS

The existing studies suggest that both the gut microbiota and exosomes contribute to the development of ALD. Moreover, there exists an interaction between the gut microbiota and exosomes. We discuss whether this interaction plays a role in the pathogenesis of ALD and whether it can be a potential therapeutic target for ALD treatment.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Chronic alcohol intake alters the diversity and composition of gut microbiota, which greatly contributes to ALD's progression. Some approaches targeting the gut microbiota, including probiotics, fecal microbiota transplantation, and phage therapy, have been confirmed to effectively ameliorate ALD in many animal experiments and/or several clinical trials. In ALD, the levels of exosomes and the expression profile of microRNA have also changed, which affects the pathogenesis of ALD. Moreover, there is an interplay between exosomes and the gut microbiota, which also putatively acts as a pathogenic factor of ALD.

Sumoylation of methionine adenosyltransferase alpha 1 promotes mitochondrial dysfunction in alcohol-associated liver disease

BACKGROUND AND AIMS

Methionine adenosyltransferase alpha1 (MATα1) is responsible for the biosynthesis of S-adenosylmethionine in normal liver. Alcohol consumption enhances MATα1 interaction with peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1), which blocks MATα1 mitochondrial targeting, resulting in lower mitochondrial MATα1 content and mitochondrial dysfunction in alcohol-associated liver disease (ALD) in part through upregulation of cytochrome P450 2E1. Conversely, alcohol intake enhances SUMOylation, which enhances cytochrome P450 2E1 expression. MATα1 has potential SUMOylation sites, but whether MATα1 is regulated by SUMOylation in ALD is unknown. Here, we investigated if MATα1 is regulated by SUMOylation and, if so, how it impacts mitochondrial function in ALD.

APPROACH AND RESULTS

Proteomics profiling revealed hyper-SUMOylation of MATα1, and prediction software identified lysine 48 (K48) as the potential SUMOylation site in mice (K47 in humans). Experiments with primary hepatocytes, mouse, and human livers revealed that SUMOylation of MAT1α by SUMO2 depleted mitochondrial MATα1. Furthermore, mutation of MATα1 K48 prevented ethanol-induced mitochondrial membrane depolarization, MATα1 depletion, and triglyceride accumulation. Additionally, CRISPR/CRISPR associated protein 9 gene editing of MATα1 at K48 hindered ethanol-induced MATα1-PIN1 interaction, degradation, and phosphorylation of MATα1 in vitro. In vivo, CRISPR/CRISPR associated protein 9 MATα1 K48 gene-edited mice were protected from ethanol-induced fat accumulation, liver injury, MATα1-PIN1 interaction, mitochondrial MATα1 depletion, mitochondrial dysfunction, and low S-adenosylmethionine levels.

CONCLUSIONS

Taken together, our findings demonstrate an essential role for SUMOylation of MATα1 K48 for interaction with PIN1 in ALD. Preventing MATα1 K48 SUMOylation may represent a potential treatment strategy for ALD.

Macrophage ATG16L1 expression suppresses metabolic dysfunction-associated steatohepatitis progression by promoting lipophagy

BACKGROUND/AIMS

Metabolic dysfunction-associated steatohepatitis (MASH) is an unmet clinical challenge due to the rapid increased occurrence but lacking approved drugs. Autophagy-related protein 16-like 1 (ATG16L1) plays an important role in the process of autophagy, which is indispensable for proper biogenesis of the autophagosome, but its role in modulating macrophage-related inflammation and metabolism during MASH has not been documented. Here, we aimed to elucidate the role of ATG16L1 in the progression of MASH.

METHODS

Expression analysis was performed with liver samples from human and mice. MASH models were induced in myeloid-specific Atg16l1-deficient and myeloid-specific Atg16l1-overexpressed mice by high-fat and high-cholesterol diet or methionine- and choline-deficient diet to explore the function and mechanism of macrophage ATG16L1 in MASH.

RESULTS

Macrophage-specific Atg16l1 knockout exacerbated MASH and inhibited energy expenditure, whereas macrophage-specific Atg16l1 transgenic overexpression attenuated MASH and promotes energy expenditure. Mechanistically, Atg16l1 knockout inhibited macrophage lipophagy, thereby suppressing macrophage β-oxidation and decreasing the production of 4-hydroxynonenal, which further inhibited stimulator of interferon genes(STING) carbonylation. STING palmitoylation was enhanced, STING trafficking from the endoplasmic reticulum to the Golgi was promoted, and downstream STING signaling was activated, promoting proinflammatory and profibrotic cytokines secretion, resulting in hepatic steatosis and hepatic stellate cells activation. Moreover, Atg16l1-deficiency enhanced macrophage phagosome ability but inhibited lysosome formation, engulfing mtDNA released by pyroptotic hepatocytes. Increased mtDNA promoted cGAS/STING signaling activation. Moreover, pharmacological promotion of ATG16L1 substantially blocked MASH progression.

CONCLUSION

ATG16L1 suppresses MASH progression by maintaining macrophage lipophagy, restraining liver inflammation, and may be a promising therapeutic target for MASH management.

Alcohol-induced Golgiphagy is triggered by the downregulation of Golgi GTPase RAB3D

The development of alcohol-associated liver disease (ALD) is associated with disorganized Golgi apparatus and accelerated phagophore formation. While Golgi membranes may contribute to phagophores, association between Golgi alterations and macroautophagy/autophagy remains unclear. GOLGA4/p230 (golgin A4), a dimeric Golgi matrix protein, participates in phagophore formation, but the underlying mechanism is elusive. Our prior research identified ethanol (EtOH)-induced Golgi scattering, disrupting intra-Golgi trafficking and depleting RAB3D GTPase from the trans-Golgi. Employing various techniques, we analyzed diverse cellular and animal models representing chronic and chronic/binge alcohol consumption. In trans-Golgi of non-treated hepatocytes, we found a triple complex formed between RAB3D, GOLGA4, and MYH10/NMIIB (myosin, heavy polypeptide 10, non-muscle). However, EtOH-induced RAB3D downregulation led to MYH10 segregation from the Golgi, accompanied by Golgi fragmentation and tethering of the MYH10 isoform, MYH9/NMIIA, to dispersed Golgi membranes. EtOH-activated autophagic flux is evident through increased WIPI2 recruitment to the Golgi, phagophore formation, enhanced LC3B lipidation, and reduced SQSTM1/p62. Although GOLGA4 dimerization and intra-Golgi localization are unaffected, loss of RAB3D leads to an extension of the cytoplasmic N terminal domain of GOLGA4, forming GOLGA4-positive phagophores. Autophagy inhibition by hydroxychloroquine (HCQ) prevents alcohol-mediated Golgi disorganization, restores distribution of ASGR (asialoglycoprotein receptor), and mitigates COL (collagen) deposition and steatosis. In contrast to short-term exposure to HCQ, extended co-treatment with both EtOH and HCQ results in the depletion of LC3B protein via proteasomal degradation. Thus, (a) RAB3D deficiency and GOLGA4 conformational changes are pivotal in MYH9-driven, EtOH-mediated Golgiphagy, and (b) HCQ treatment holds promise as a therapeutic approach for alcohol-induced liver injury.Abbreviation: ACTB: actin, beta; ALD: alcohol-associated liver disease; ASGR: asialoglycoprotein receptor; AV: autophagic vacuoles; EM: electron microscopy; ER: endoplasmic reticulum; EtOH: ethanol; HCQ: hydroxychloroquine; IP: immunoprecipitation; KD: knockdown; KO: knockout; MYH10/NMIIB: myosin, heavy polypeptide 10, non-muscle; MYH9/NMIIA: myosin, heavy polypeptide 9, non-muscle; PLA: proximity ligation assay; ORO: Oil Red O staining; PM: plasma membrane; TGN: trans-Golgi network; SIM: structured illumination super-resolution microscopy.

Morroniside delays the progression of non-alcoholic steatohepatitis by promoting AMPK-mediated lipophagy

BACKGROUND

Non-alcoholic steatohepatitis (NASH), the inflammatory subtype in the progression of non-alcoholic fatty liver disease, is becoming a serious burden threatening human health, but no approved medication is available to date. Mononoside is a natural active substance derived from Cornus officinalis and has been confirmed to have great potential in regulating lipid metabolism in our previous studies. However, its effect and mechanism to inhibit the progression of NASH remains unclear.

PURPOSE

Our work aimed to explore the action of mononoside in delaying the progression of NASH and its regulatory mechanisms from the perspective of regulating lipophagy.

METHODS AND RESULTS

Male C57BL/6 mice were fed with a high-fat and high-fructose diet for 16 weeks to establish a NASH mouse model. After 8 weeks of high-fat and high-fructose feeding, these mice were administrated with different doses of morroniside. H&E staining, ORO staining, Masson staining, RNA-seq, immunoblotting, and immunofluorescence were performed to determine the effects and molecular mechanisms of morroniside in delaying the progression of NASH. In this study, we found that morroniside is effective in attenuating hepatic lipid metabolism disorders and inflammatory response activation, thereby limiting the progression from simple fatty liver to NASH in high-fat and high-fructose diet-fed mice. Mechanistically, we identified AMPK signaling as the key molecular pathway for the positive efficacy of morroniside by transcriptome sequencing. Our results revealed that morroniside maintained hepatic lipid metabolism homeostasis and inhibited NLRP3 inflammasome activation by promoting AMPKα phosphorylation-mediated lipophagy and fatty acid oxidation. Consistent results were observed in palmitic acid-treated cell models. Of particular note, silencing AMPKα both in vivo and in vitro reversed morroniside-induced lipophagy flux enhancement and NLRP3 inflammasome inhibition, emphasizing the critical role of AMPKα activation in the effect of morroniside in inhibiting NASH progression.

CONCLUSION

In summary, the present study provides strong evidence for the first time that morroniside inhibits NASH progression by promoting AMPK-dependent lipophagy and inhibiting NLRP3 inflammasome activation, suggesting that morroniside is expected to be a potential molecular entity for the development of therapeutic drugs for NASH.

IL-37d suppresses Rheb-mTORC1 axis independently of TCS2 to alleviate alcoholic liver disease

Tuberous sclerosis complex 2 (TSC2) crucially suppresses Rheb activity to prevent mTORC1 activation. However, mutations in TSC genes lead to mTORC1 overactivation, thereby causing various developmental disorders and cancer. Therefore, the discovery of novel Rheb inhibitors is vital to prevent mTOR overactivation. Here, we reveals that the anti-inflammatory cytokine IL-37d can bind to lysosomal Rheb and suppress its activity independent of TSC2, thereby preventing mTORC1 activation. The binding of IL-37d to Rheb switch-II subregion destabilizes the Rheb-mTOR and mTOR-S6K interactions, further halting mTORC1 signaling. Unlike TSC2, IL-37d is reduced under ethanol stimulation, which results in mitigating the suppression of lysosomal Rheb-mTORC1 activity. Consequently, the recombinant human IL-37d protein (rh-IL-37d) with a TAT peptide greatly improves alcohol-induced liver disorders by hindering Rheb-mTORC1 axis overactivation in a TSC2- independent manner. Together, IL-37d emerges as a novel Rheb suppressor independent of TSC2 to terminate mTORC1 activation and improve abnormal lipid metabolism in the liver.

Copper Chelation Therapy Attenuates Periodontitis Inflammation through the Cuproptosis/Autophagy/Lysosome Axis

Periodontitis development arises from the intricate interplay between bacterial biofilms and the host's immune response, where macrophages serve pivotal roles in defense and tissue homeostasis. Here, we uncover the mitigative effect of copper chelator Tetrathiomolybdate (TTM) on periodontitis through inhibiting cuproptosis, a newly identified form of cell death which is dependent on copper. Our study reveals concurrent cuproptosis and a macrophage marker within murine models. In response to lipopolysaccharide (LPS) stimulation, macrophages exhibit elevated cuproptosis-associated markers, which are mitigated by the administration of TTM. TTM treatment enhances autophagosome expression and mitophagy-related gene expression, countering the LPS-induced inhibition of autophagy flux. TTM also attenuates the LPS-induced fusion of autophagosomes and lysosomes, the degradation of lysosomal acidic environments, lysosomal membrane permeability increase, and cathepsin B secretion. In mice with periodontitis, TTM reduces cuproptosis, enhances autophagy flux, and decreases Ctsb levels. Our findings underscore the crucial role of copper-chelating agent TTM in regulating the cuproptosis/mitophagy/lysosome pathway during periodontitis inflammation, suggesting TTM as a promising approach to alleviate macrophage dysfunction. Modulating cuproptosis through TTM treatment holds potential for periodontitis intervention.

SS-31 inhibits the inflammatory response by increasing ATG5 and promoting autophagy in lipopolysaccharide-stimulated HepG2 cells

SS-31 is a mitochondria-targeting short peptide. Recent studies have indicated its hepatoprotective effects. In our study, we investigated the impact of SS-31 on LPS-induced autophagy in HepG2 cells. The results obtained from a dual-fluorescence autophagy detection system revealed that SS-31 promotes the formation of autolysosomes and autophagosomes, thereby facilitating autophagic flux to a certain degree. Additionally, both ELISA and qPCR analyses provided further evidence that SS-31 safeguards HepG2 cells against inflammatory responses triggered by LPS through ATG5-dependent autophagy. In summary, our study demonstrates that SS-31 inhibits LPS-stimulated inflammation in HepG2 cells by upregulating ATG5-dependent autophagy.

Evaluation of hepatic AMPK, mTORC1, and autophagy-lysosomal pathway in cows with mild or moderate fatty liver

The aim of the present study was to investigate the activity of AMPK and mTORC1 as well as TFEB transcriptional activity and autophagy-lysosomal function in the liver of dairy cows with mild fatty liver (FL) and cows with moderate FL. Liver and blood samples were collected from healthy dairy cows (n = 10; hepatic triglyceride content <1% wet weight) and cows with mild FL (n = 10; 1% ≤ hepatic triglyceride content < 5% wet weight) or moderate FL (n = 10; 5% ≤ hepatic triglyceride content < 10% wet weight) that had a similar number of lactations (median = 3, range = 2-4) and days in milk (median = 6 d, range = 3-9). Blood parameters were determined using a Hitachi 3130 autoanalyzer with commercially available kits. Protein and mRNA abundances were determined using western blotting and quantitative real-time PCR, respectively. Activities of calcineurin and β-N-acetylglucosaminidase were measured with commercial assay kits. Data were analyzed using one-way ANOVA with subsequent Bonferroni correction. Blood concentrations of glucose were lower in moderate FL cows (3.03 ± 0.21 mM) than in healthy (3.71 ± 0.14 mM) and mild FL cows (3.76 ± 0.14 mM). Blood concentrations of β-hydroxybutyrate (BHB, 1.37 ± 0.15 mM in mild FL, 1.88 ± 0.17 mM in moderate FL) and free fatty acids (FFA, 0.69 ± 0.05 mM in mild FL, 0.96 ± 0.09 mM in moderate FL) were greater in FL cows than in healthy cows (BHB, 0.76 ± 0.12 mM; FFA, 0.42 ± 0.04 mM). Compared with healthy cows, phosphorylation of AMPK was greater and phosphorylation of its downstream target acetyl-CoA carboxylase 1 was lower in cows with mild and moderate FL. Phosphorylation of mTOR was lower in cows with mild FL compared with healthy cows. In cows with moderate FL, phosphorylation of mTOR and its downstream effectors was greater than in healthy cows and cows with mild FL. The mRNA abundance of TFEB was downregulated in cows with moderate FL compared with healthy cows and mild FL cows. In mild FL cows, the mRNA and protein abundances of TFEB were greater than in healthy cows. Compared with healthy cows, the mRNA abundances of autophagy markers sequestosome-1 and microtubule-associated protein 1 light chain 3-II, and the protein and mRNA abundances of lysosome-associated membrane protein 1 and cathepsin D were increased in mild FL cows but decreased in moderate FL cows. Compared with healthy cows, the mRNA abundance of mucolipin 1 and activities of β-N-acetylglucosaminidase and calcineurin were higher in cows with mild FL but lower in cows with moderate FL. These data demonstrate that hepatic AMPK signaling pathway, TFEB transcriptional activity, and autophagy-lysosomal function are increased in dairy cows with mild FL; the hepatic mTORC1 signaling pathway is inhibited in mild FL cows but activated in moderate FL cows; and activities of AMPK and TFEB as well as autophagy-lysosomal function are impaired in moderate FL cows.

The interplay between autophagy and ferroptosis presents a novel conceptual therapeutic framework for neuroendocrine prostate cancer

In American men, the incidence of prostate cancer (PC) is the highest among all types of cancer, making it the second leading cause of mortality associated with cancer. For advanced or metastatic PC, antiandrogen therapies are standard treatment options. The administration of these treatments unfortunately carries the potential risk of inducing neuroendocrine prostate cancer (NEPC). Neuroendocrine differentiation (NED) serves as a crucial indicator of prostate cancer development, encompassing various factors such as phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR), Yes-associated protein 1 (YAP1), AMP-activated protein kinase (AMPK), miRNA. The processes of autophagy and ferroptosis (an iron-dependent form of programmed cell death) play pivotal roles in the regulation of various types of cancers. Clinical trials and preclinical investigations have been conducted on many signaling pathways during the development of NEPC, with the deepening of research, autophagy and ferroptosis appear to be the potential target for regulating NEPC. Due to the dual nature of autophagy and ferroptosis in cancer, gaining a deeper understanding of the developmental programs associated with achieving autophagy and ferroptosis may enhance risk stratification and treatment efficacy for patients with NEPC.

Tangshen formula protects against podocyte apoptosis via enhancing the TFEB-mediated autophagy-lysosome pathway in diabetic nephropathy

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease and currently there are no specific and effective drugs for its treatment. Podocyte injury is a detrimental feature and the major cause of albuminuria in DN. We previously reported Tangshen Formula (TSF), a Chinese herbal medicine, has shown therapeutic effects on DN. However, the underlying mechanisms remain obscure.

AIM OF THE STUDY

This study aimed to explore the protective effect of TSF on podocyte apoptosis in DN and elucidate the potential mechanism.

MATERIALS AND METHODS

The effects of TSF were assessed in a murine model using male KKAy diabetic mice, as well as in advanced glycation end products-stimulated primary mice podocytes. Transcription factor EB (TFEB) knockdown primary podocytes were employed for mechanistic studies. In vivo and in vitro studies were performed and results assessed using transmission electron microscopy, immunofluorescence staining, and western blotting.

RESULTS

TSF treatment alleviated podocyte apoptosis and structural impairment, decreased albuminuria, and mitigated renal dysfunction in KKAy mice. Notably, TSF extracted twice showed a more significant reduction in proteinuria than TSF extracted three times. Accumulation of autophagic biomarkers p62 and LC3, and aberrant autophagic flux in podocytes of DN mice were significantly altered by TSF therapy. Consistent with the in vivo results, TSF prevented the apoptosis of primary podocytes exposed to AGEs and activated autophagy. However, the anti-apoptosis capacity of TSF was countered by the autophagy-lysosome inhibitor chloroquine. We found that TSF increased the nuclear translocation of TFEB in diabetic podocytes, and thus upregulated transcription of its several autophagic target genes. Pharmacological activation of TFEB by TSF accelerated the conversion of autophagosome to autolysosome and lysosomal biogenesis, further augmented autophagic flux. Conversely, TFEB knockdown negated the favorable effects of TSF on autophagy in AGEs-stimulated primary podocytes.

CONCLUSIONS

These findings indicate TSF appears to attenuate podocyte apoptosis and promote autophagy in DN via the TFEB-mediated autophagy-lysosome system. Thus, TSF may be a therapeutic candidate for DN.

Membrane-bound O-acyltransferase 7 (MBOAT7) shapes lysosomal lipid homeostasis and function to control alcohol-associated liver injury

Recent genome-wide association studies (GWAS) have identified a link between single-nucleotide polymorphisms (SNPs) near the MBOAT7 gene and advanced liver diseases. Specifically, the common MBOAT7 variant (rs641738) associated with reduced MBOAT7 expression is implicated in non-alcoholic fatty liver disease (NAFLD), alcohol-associated liver disease (ALD), and liver fibrosis. However, the precise mechanism underlying MBOAT7-driven liver disease progression remains elusive. Previously, we identified MBOAT7-driven acylation of lysophosphatidylinositol lipids as key mechanism suppressing the progression of NAFLD (Gwag et al., 2019). Here, we show that MBOAT7 loss of function promotes ALD via reorganization of lysosomal lipid homeostasis. Circulating levels of MBOAT7 metabolic products are significantly reduced in heavy drinkers compared to healthy controls. Hepatocyte- (Mboat7-HSKO), but not myeloid-specific (Mboat7-MSKO), deletion of Mboat7 exacerbates ethanol-induced liver injury. Lipidomic profiling reveals a reorganization of the hepatic lipidome in Mboat7-HSKO mice, characterized by increased endosomal/lysosomal lipids. Ethanol-exposed Mboat7-HSKO mice exhibit dysregulated autophagic flux and lysosomal biogenesis, associated with impaired transcription factor EB-mediated lysosomal biogenesis and autophagosome accumulation. This study provides mechanistic insights into how MBOAT7 influences ALD progression through dysregulation of lysosomal biogenesis and autophagic flux, highlighting hepatocyte-specific MBOAT7 loss as a key driver of ethanol-induced liver injury.

A snake cathelicidin enhances transcription factor EB-mediated autophagy and alleviates ROS-induced pyroptosis after ischaemia-reperfusion injury of island skin flaps

BACKGROUND AND PURPOSE

Ischaemia-reperfusion (I/R) injury is a major contributor to skin flap necrosis, which presents a challenge in achieving satisfactory therapeutic outcomes. Previous studies showed that cathelicidin-BF (BF-30) protects tissues from I/R injury. In this investigation, BF-30 was synthesized and its role and mechanism in promoting survival of I/R-injured skin flaps explored.

EXPERIMENTAL APPROACH

Survival rate analysis and laser Doppler blood flow analysis were used to evaluate I/R-injured flap viability. Western blotting, immunofluorescence, TdT-mediated dUTP nick end labelling (TUNEL) and dihydroethidium were utilized to examine the levels of apoptosis, pyroptosis, oxidative stress, transcription factor EB (TFEB)-mediated autophagy and molecules related to the adenosine 5'-monophosphate-activated protein kinase (AMPK)-transient receptor potential mucolipin 1 (TRPML1)-calcineurin signalling pathway.

KEY RESULTS

The outcomes revealed that BF-30 enhanced I/R-injured island skin flap viability. Autophagy, oxidative stress, pyroptosis and apoptosis were related to the BF-30 capability to enhance I/R-injured flap survival. Improved autophagy flux and tolerance to oxidative stress promoted the inhibition of apoptosis and pyroptosis in vascular endothelial cells. Activation of TFEB increased autophagy and inhibited endothelial cell oxidative stress in I/R-injured flaps. A reduction in TFEB level led to a loss of the protective effect of BF-30, by reducing autophagy flux and increasing the accumulation of reactive oxygen species (ROS) in endothelial cells. Additionally, BF-30 modulated TFEB activity via the AMPK-TRPML1-calcineurin signalling pathway.

CONCLUSION AND IMPLICATIONS

BF-30 promotes I/R-injured skin flap survival by TFEB-mediated up-regulation of autophagy and inhibition of oxidative stress, which may have possible clinical applications.

Beneficial Effect of Rapamycin on Liver Fibrosis in a Mouse Model (C57bl/6 Mouse)

BACKGROUND

Liver fibrosis is a chronic inflammatory disease that progresses and has a high mortality rate. This study was performed to investigate the protective effect of rapamycin on experimentally induced chronic liver injury in mice models using both biochemical parameters of liver function enzymes.

METHODS

Twenty-four mice were divided randomly into 4 equal groups: [1] the normal group, n = 6; [2] the liver fibrosis (LF) group, n = 6; [3] the LF with the treatment of rapamycin group, n = 6; [4] the LF with the treatment of silimaryn, n = 6.

RESULTS

In the group receiving oral administration of rapamycin, aspartate aminotransferase, alanine aminotransferase, urea, and creatinine were found to significantly decrease compared to the liver fibrosis group. Rapamycin, in the orally administered group, demonstrated a statistically significant decrease in the expression of interleukin (IL) 10, IL-1B, inducible nitric oxide synthase, and tumor necrosis factor alpha compared to the liver fibrosis group.

CONCLUSIONS

In this study, we explored the potential therapeutic effects of rapamycin on liver fibrosis in an animal model.

Toosendanin induces hepatotoxicity by restraining autophagy and lysosomal function through inhibiting STAT3/CTSC axis

Toosendanin (TSN) is the main active component in the traditional herb Melia toosendan Siebold & Zucc, which exhibits promising potential for development due to its diverse pharmacological properties. However, the hepatotoxicity associated with TSN needs further investigation. Previous research has implicated autophagy dysregulation in TSN-induced hepatotoxicity, yet the underlying mechanisms remain elusive. In this study, the mechanisms of signal transducer and activator of transcription 3 (STAT3) in TSN-induced autophagy inhibition and liver injury were explored using Stat3 knockout C57BL/6 mice and HepG2 cells. TSN decreased cell viability, increased lactate dehydrogenase (LDH) production in vitro, and elevated serum aspartate transaminase (AST) and alanine aminotransferase (ALT) levels as well as liver lesions in vivo, suggesting TSN had significant hepatotoxicity. TSN inhibited Janus kinase 2 (JAK2)/STAT3 pathway and the expression of cathepsin C (CTSC). Inhibition of STAT3 exacerbated TSN-induced autophagy inhibition and hepatic injury, whereas activation of STAT3 attenuated these effects of TSN. Mechanistically, STAT3 transcriptionally regulated the level of CTSC gene, which in turn affected autophagy and the process of liver injury. TSN-administered Stat3 knockout mice showed more severe hepatotoxicity, CTSC downregulation, and autophagy blockade than wildtype mice. In summary, TSN caused hepatotoxicity by inhibiting STAT3/CTSC axis-dependent autophagy and lysosomal function.

Recent advances in host-focused molecular tools for investigating host-gut microbiome interactions

Microbial communities in the human gut play a significant role in regulating host gene expression, influencing a variety of biological processes. To understand the molecular mechanisms underlying host-microbe interactions, tools that can dissect signaling networks are required. In this review, we discuss recent advances in molecular tools used to study this interplay, with a focus on those that explore how the microbiome regulates host gene expression. These tools include CRISPR-based whole-body genetic tools for deciphering host-specific genes involved in the interaction process, Cre-loxP based tissue/cell-specific gene editing approaches, and in vitro models of host-derived organoids. Overall, the application of these molecular tools is revolutionizing our understanding of how host-microbiome interactions contribute to health and disease, paving the way for improved therapies and interventions that target microbial influences on the host.

Late-Life Alcohol Exposure Does Not Exacerbate Age-Dependent Reductions in Mouse Spatial Memory and Brain TFEB Activity

Alcohol consumption is believed to affect Alzheimer's disease (AD) risk, but the contributing mechanisms are not well understood. A potential mediator of the proposed alcohol-AD connection is autophagy, a degradation pathway that maintains organelle and protein homeostasis. Autophagy is in turn regulated through the activity of Transcription factor EB (TFEB), which promotes lysosome and autophagy-related gene expression. To explore the effect of alcohol on brain TFEB and autophagy, we exposed young (3-month old) and aged (23-month old) mice to two alcohol-feeding paradigms and assessed biochemical, transcriptome, histology, and behavioral endpoints. In young mice, alcohol decreased hippocampal nuclear TFEB staining but increased SQSTM1/p62, LC3-II, ubiquitinated proteins, and phosphorylated Tau. Hippocampal TFEB activity was lower in aged mice than it was in young mice, and Gao-binge alcohol feeding did not worsen the age-related reduction in TFEB activity. To better assess the impact of chronic alcohol exposure, we fed young and aged mice alcohol for four weeks before completing Morris Water and Barnes Maze spatial memory testing. The aged mice showed worse spatial memory on both tests. While alcohol feeding slightly impaired spatial memory in the young mice, it had little effect or even slightly improved spatial memory in the aged mice. These findings suggest that aging is a far more important driver of spatial memory impairment and reduced autophagy flux than alcohol consumption.

Ezrin inhibition alleviates oxidative stress and pyroptosis via regulating TRPML1-calcineurin axis mediated enhancement of autophagy in spinal cord injury

Spinal cord injury (SCI) presents profound ramifications for patients, leading to diminished motor and sensory capabilities distal to the lesion site. Once SCI occurs, it not only causes great physical and psychological problems for patients but also imposes a heavy economic burden. Ezrin is involved in various cellular processes, including signal transduction, cell death, inflammation, chemotherapy resistance and the stress response. However, whether Ezrin regulates functional repair after SCI and its underlying mechanism has not been elucidated. Here, our results showed that there is a marked augmentation of Ezrin levels within neurons and Ezrin inhibition markedly diminished glial scarring and bolstered functional recuperation after SCI. RNA sequencing indicated the potential involvement of pyroptosis, oxidative stress and autophagy in the enhancement of functional recovery upon reduced Ezrin expression. Moreover, the inhibition of Ezrin expression curtailed pyroptosis and oxidative stress by amplifying autophagy. Our studies further demonstrated that Ezrin inhibition promoted autophagy by increasing TFEB activity via the Akt-TRPML1-calcineurin pathway. Finally, we concluded that inhibiting Ezrin expression alleviates pyroptosis and oxidative stress by enhancing TFEB-driven autophagy, thereby promoting functional recovery after SCI, which may be a promising therapeutic target for SCI treatment.

From the regulatory mechanism of TFEB to its therapeutic implications

Transcription factor EB (TFEB), known as a major transcriptional regulator of the autophagy-lysosomal pathway, regulates target gene expression by binding to coordinated lysosomal expression and regulation (CLEAR) elements. TFEB are regulated by multiple links, such as transcriptional regulation, post-transcriptional regulation, translational-level regulation, post-translational modification (PTM), and nuclear competitive regulation. Targeted regulation of TFEB has been victoriously used as a treatment strategy in several disease models such as ischemic injury, lysosomal storage disorders (LSDs), cancer, metabolic disorders, neurodegenerative diseases, and inflammation. In this review, we aimed to elucidate the regulatory mechanism of TFEB and its applications in several disease models by targeting the regulation of TFEB as a treatment strategy.

Ethanol changes Nestin-promoter induced neural stem cells to disturb newborn dendritic spine remodeling in the hippocampus of mice

Adolescent binge drinking leads to long-lasting disorders of the adult central nervous system, particularly aberrant hippocampal neurogenesis. In this study, we applied in vivo fluorescent tracing using NestinCreERT2::Rosa26-tdTomato mice and analyzed the endogenous neurogenesis lineage progression of neural stem cells (NSCs) and dendritic spine formation of newborn neurons in the subgranular zone of the dentate gyrus. We found abnormal orientation of tamoxifen-induced tdTomato+ (tdTom+) NSCs in adult mice 2 months after treatment with EtOH (5.0 g/kg, i.p.) for 7 consecutive days. EtOH markedly inhibited tdTom+ NSCs activation and hippocampal neurogenesis in mouse dentate gyrus from adolescence to adulthood. EtOH (100 mM) also significantly inhibited the proliferation to 39.2% and differentiation of primary NSCs in vitro. Adult mice exposed to EtOH also exhibited marked inhibitions in dendritic spine growth and newborn neuron maturation in the dentate gyrus, which was partially reversed by voluntary running or inhibition of the mammalian target of rapamycin-enhancer of zeste homolog 2 pathway. In vivo tracing revealed that EtOH induced abnormal orientation of tdTom+ NSCs and spatial misposition defects of newborn neurons, thus causing the disturbance of hippocampal neurogenesis and dendritic spine remodeling in mice.

Mechanisms and therapeutic implications of selective autophagy in nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide, whereas there is no approved drug therapy due to its complexity. Studies are emerging to discuss the role of selective autophagy in the pathogenesis of NAFLD, because the specificity among the features of selective autophagy makes it a crucial process in mitigating hepatocyte damage caused by aberrant accumulation of dysfunctional organelles, for which no other pathway can compensate.

AIM OF REVIEW

This review aims to summarize the types, functions, and dynamics of selective autophagy that are of particular importance in the initiation and progression of NAFLD. And on this basis, the review outlines the therapeutic strategies against NAFLD, in particular the medications and potential natural products that can modulate selective autophagy in the pathogenesis of this disease.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The critical roles of lipophagy and mitophagy in the pathogenesis of NAFLD are well established, while reticulophagy and pexophagy are still being identified in this disease due to the insufficient understanding of their molecular details. As gradual blockage of autophagic flux reveals the complexity of NAFLD, studies unraveling the underlying mechanisms have made it possible to successfully treat NAFLD with multiple pharmacological compounds that target associated pathways. Overall, it is convinced that the continued research into selective autophagy occurring in NAFLD will further enhance the understanding of the pathogenesis and uncover novel therapeutic targets.

Naringin Protects against Non-Alcoholic Fatty Liver Disease by Promoting Autophagic Flux and Lipophagy

The autophagic degradation of lipid droplets, termed lipophagy, is the main mechanism contributing to lipid consumption in hepatocytes. Identifying effective and safe natural compounds that target lipophagy to eliminate excess lipids may be a potential therapeutic strategy for non-alcoholic fatty liver disease (NAFLD). Here the effects of naringin on NAFLD and the underlying mechanisms involved are investigated. Naringin treatment effectively relieves HFD-induced hepatic steatosis in mice and inhibits PA-induced lipid accumulation in hepatocytes. Increased p62 and LC3-II levels are observed with excess lipid support autophagosome accumulation and impaired autophagic flux. Treatment with naringin restores TFEB-mediated lysosomal biogenesis, thereby promoting the fusion of autophagosomes and lysosomes, restoring impaired autophagic flux and further inducing lipophagy. However, the knockdown of TFEB in hepatocytes or the hepatocyte-specific knockout of TFEB in mice abrogates naringin-induced lipophagy, eliminating its therapeutic effect on hepatic steatosis. These results demonstrate that TFEB-mediated lysosomal biogenesis and subsequent lipophagy play essential roles in the ability of naringin to mitigate hepatic steatosis and suggest that naringin is a promising drug for treating NAFLD.

Research progress on rodent models and its mechanisms of liver injury

The liver is the most important organ for biological transformation in the body and is crucial for maintaining the body's vital activities. Liver injury is a serious pathological condition that is commonly found in many liver diseases. It has a high incidence rate, is difficult to cure, and is prone to recurrence. Liver injury can cause serious harm to the body, ranging from mild to severe fatty liver disease. If the condition continues to worsen, it can lead to liver fibrosis and cirrhosis, ultimately resulting in liver failure or liver cancer, which can seriously endanger human life and health. Therefore, establishing an rodent model that mimics the pathogenesis and severity of clinical liver injury is of great significance for better understanding the pathogenesis of liver injury patients and developing more effective clinical treatment methods. The author of this article summarizes common chemical liver injury models, immune liver injury models, alcoholic liver injury models, drug-induced liver injury models, and systematically elaborates on the modeling methods, mechanisms of action, pathways of action, and advantages or disadvantages of each type of model. The aim of this study is to establish reliable rodent models for researchers to use in exploring anti-liver injury and hepatoprotective drugs. By creating more accurate theoretical frameworks, we hope to provide new insights into the treatment of clinical liver injury diseases.

Membrane Bound O-Acyltransferase 7 (MBOAT7) Shapes Lysosomal Lipid Homeostasis and Function to Control Alcohol-Associated Liver Injury

Several recent genome-wide association studies (GWAS) have identified single nucleotide polymorphism (SNPs) near the gene encoding membrane-bound O -acyltransferase 7 ( MBOAT7 ) that is associated with advanced liver diseases. In fact, a common MBOAT7 variant (rs641738), which is associated with reduced MBOAT7 expression, confers increased susceptibility to non-alcoholic fatty liver disease (NAFLD), alcohol-associated liver disease (ALD), and liver fibrosis in those chronically infected with hepatitis viruses B and C. The MBOAT7 gene encodes a lysophosphatidylinositol (LPI) acyltransferase enzyme that produces the most abundant form of phosphatidylinositol 38:4 (PI 18:0/20:4). Although these recent genetic studies clearly implicate MBOAT7 function in liver disease progression, the mechanism(s) by which MBOAT7-driven LPI acylation regulates liver disease is currently unknown. Previously we showed that antisense oligonucleotide (ASO)-mediated knockdown of Mboat7 promoted non-alcoholic fatty liver disease (NAFLD) in mice (Helsley et al., 2019). Here, we provide mechanistic insights into how MBOAT7 loss of function promotes alcohol-associated liver disease (ALD). In agreement with GWAS studies, we find that circulating levels of metabolic product of MBOAT7 (PI 38:4) are significantly reduced in heavy drinkers compared to age-matched healthy controls. Hepatocyte specific genetic deletion ( Mboat7 HSKO ), but not myeloid-specific deletion ( Mboat7 MSKO ), of Mboat7 in mice results in enhanced ethanol-induced hepatic steatosis and high concentrations of plasma alanine aminotransferase (ALT). Given MBOAT7 is a lipid metabolic enzyme, we performed comprehensive lipidomic profiling of the liver and identified a striking reorganization of the hepatic lipidome upon ethanol feeding in Mboat7 HSKO mice. Specifically, we observed large increases in the levels of endosomal/lysosomal lipids including bis(monoacylglycero)phosphates (BMP) and phosphatidylglycerols (PGs) in ethanol-exposed Mboat7 HSKO mice. In parallel, ethanol-fed Mboat7 HSKO mice exhibited marked dysregulation of autophagic flux and lysosomal biogenesis when exposed to ethanol. This was associated with impaired transcription factor EB (TFEB)-mediated lysosomal biogenesis and accumulation of autophagosomes. Collectively, this works provides new molecular insights into how genetic variation in MBOAT7 impacts ALD progression in humans and mice. This work is the first to causally link MBOAT7 loss of function in hepatocytes, but not myeloid cells, to ethanol-induced liver injury via dysregulation of lysosomal biogenesis and autophagic flux.

High-throughput screening of novel TFEB agonists in protecting against acetaminophen-induced liver injury in mice

Macroautophagy (referred to as autophagy hereafter) is a major intracellular lysosomal degradation pathway that is responsible for the degradation of misfolded/damaged proteins and organelles. Previous studies showed that autophagy protects against acetaminophen (APAP)-induced injury (AILI) via selective removal of damaged mitochondria and APAP protein adducts. The lysosome is a critical organelle sitting at the end stage of autophagy for autophagic degradation via fusion with autophagosomes. In the present study, we showed that transcription factor EB (TFEB), a master transcription factor for lysosomal biogenesis, was impaired by APAP resulting in decreased lysosomal biogenesis in mouse livers. Genetic loss-of and gain-of function of hepatic TFEB exacerbated or protected against AILI, respectively. Mechanistically, overexpression of TFEB increased clearance of APAP protein adducts and mitochondria biogenesis as well as SQSTM1/p62-dependent non-canonical nuclear factor erythroid 2-related factor 2 (NRF2) activation to protect against AILI. We also performed an unbiased cell-based imaging high-throughput chemical screening on TFEB and identified a group of TFEB agonists. Among these agonists, salinomycin, an anticoccidial and antibacterial agent, activated TFEB and protected against AILI in mice. In conclusion, genetic and pharmacological activating TFEB may be a promising approach for protecting against AILI.

Nuciferine protects bovine hepatocytes against free fatty acid-induced oxidative damage by activating the transcription factor EB/peroxisome proliferator-activated receptor γ coactivator 1 alpha pathway

Excessive free fatty acid (FFA) oxidation and related metabolism are the major cause of oxidative stress and liver injury in dairy cows during the early postpartum period. In nonruminants, activation of transcription factor EB (TFEB) can improve cell damage and reduce the overproduction of mitochondrial reactive oxygen species. As a downstream target of TFEB, peroxisome proliferator-activated receptor γ coactivator 1 α (PGC-1α, gene name PPARGC1A) is a critical regulator of oxidative metabolism. Nuciferine (Nuc), a major bioactive compound isolated from the lotus leaf, has been reported to possess hepatoprotective activity. Therefore, the objective of this study was to investigate whether Nuc could protect bovine hepatocytes from FFA-induced lipotoxicity and the underlying mechanisms. A mixture of FFA was diluted in RPMI-1640 basic medium containing 2% low fatty acid bovine serum albumin to treat hepatocytes. Bovine hepatocytes were isolated from newborn calves and treated with various concentrations of FFA mixture (0, 0.3, 0.6, or 1.2 mM) or Nuc (0, 25, 50, or 100 μM), as well as co-treated with 1.2 mM FFA and different concentrations of Nuc. For the experiments of gene silencing, bovine hepatocytes were transfected with small interfering RNA targeted against TFEB or PPARGC1A for 36 h followed by treatment with 1.2 mM FFA for 12 h in presence or absence of 100 μΜ Nuc. The results revealed that FFA treatment decreased protein abundance of nuclear TFEB, cytosolic TFEB, total (t)-TFEB, lysosome-associated membrane protein 1 (LAMP1) and PGC-1α and mRNA abundance of LAMP1, but increased phosphorylated (p)-TFEB. In addition, FFA treatment increased the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2) and decreased the activities of catalase (CAT) and glutathione peroxidase (GSH-Px) in bovine hepatocytes. Moreover, FFA administration enhanced the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactose dehydrogenase (LDH) in the medium of FFA-treated hepatocytes, but reduced the content of urea. In FFA-treated bovine hepatocytes, Nuc administration increased TFEB nuclear localization and the protein abundance of t-TFEB, LAMP1, and PGC-1α and mRNA abundance of LAMP1, decreased the contents of MDA and H2O2 and the protein abundance of p-TFEB, and enhanced the activities of CAT and GSH-Px in a dose-dependent manner. Consistently, Nuc administration reduced the activities of ALT, AST, and LDH and increased the content of urea in the medium of FFA-treated hepatocytes. Importantly, knockdown of TFEB reduced the protein abundance of p-TFEB, t-TFEB, LAMP1, and PGC-1α and mRNA abundance of LAMP1, and impeded the beneficial effects of Nuc on FFA-induced oxidative damage in bovine hepatocytes. In addition, PPARGC1A silencing did not alter Nuc-induced nuclear translocation of TFEB, increase of the protein abundance of t-TFEB, LAMP1, and PGC-1α and mRNA abundance of LAMP1, or decrease of the protein abundance of p-TFEB, whereas it partially reduced the beneficial effects of Nuc on FFA-caused oxidative injury. Taken together, Nuc exerts protective effects against FFA-induced oxidative damage in bovine hepatocytes through activation of the TFEB/PGC-1α signaling pathway.

Novel insights into the regulatory role of N6-methyladenosine methylation modified autophagy in sepsis

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. It is characterized by high morbidity and mortality and one of the major diseases that seriously hang over global human health. Autophagy is a crucial regulator in the complicated pathophysiological processes of sepsis. The activation of autophagy is known to be of great significance for protecting sepsis induced organ dysfunction. Recent research has demonstrated that N6-methyladenosine (m6A) methylation is a well-known post-transcriptional RNA modification that controls epigenetic and gene expression as well as a number of biological processes in sepsis. In addition, m6A affects the stability, export, splicing and translation of transcripts involved in the autophagic process. Although it has been suggested that m6A methylation regulates the biological metabolic processes of autophagy and is more frequently seen in the progression of sepsis pathogenesis, the underlying molecular mechanisms of m6A-modified autophagy in sepsis have not been thoroughly elucidated. The present article fills this gap by providing an epigenetic review of the processes of m6A-modified autophagy in sepsis and its potential role in the development of novel therapeutics.

The intersection between alcohol-related liver disease and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) and alcohol-related liver disease (ALD) are the leading causes of chronic liver disease worldwide. NAFLD and ALD share pathophysiological, histological and genetic features and both alcohol and metabolic dysfunction coexist as aetiological factors in many patients with hepatic steatosis. A diagnosis of NAFLD requires the exclusion of significant alcohol consumption and other causes of liver disease. However, data suggest that significant alcohol consumption is often under-reported in patients classified as having NAFLD and that alcohol and metabolic factors interact to exacerbate the progression of liver disease. In this Review, we analyse existing data on the interaction between alcohol consumption and metabolic syndrome as well as the overlapping features and differences in the pathogenesis of ALD and NAFLD. We also discuss the clinical implications of the coexistence of alcohol consumption, of any degree, in patients with evidence of metabolic derangement as well as the use of alcohol biomarkers to detect alcohol intake. Finally, we summarize the evolving nomenclature of fatty liver disease and describe a recent proposal to classify patients at the intersection of NAFLD and ALD. We propose that, regardless of the presumed aetiology, patients with fatty liver disease should be evaluated for both metabolic syndrome and alcohol consumption to enable better prognostication and a personalized medicine approach.

The mechanistic interplay between Nrf-2, NF-κB/MAPK, caspase-dependent apoptosis, and autophagy in the hepatoprotective effects of Sophorolipids produced by microbial conversion of banana peels using Saccharomyces cerevisiae against doxorubicin-induced hepatotoxicity in rats

BACKGROUND

Doxorubicin (DOX) is a well-known chemotherapeutic agent which causes serious adverse effects due to multiple organ damage, including cardiotoxicity, nephrotoxicity, neurotoxicity, and hepatotoxicity. The mechanism of DOX-induced organ toxicity might be attributed to oxidative stress (OS) and, consequently, activation of inflammatory signaling pathways, apoptosis, and blockage of autophagy. Sophorolipids (SLs) as a glycolipid type of biosurfactants, are natural products that have unique properties and a wide range of applications attributed to their antioxidant and anti-inflammatory properties.

AIMS

Production of low-cost SLs from Saccharomyces cerevisiae grown on banana peels and investigating their possible protective effects against DOX-induced hepatotoxicity.

MAIN METHODS

The yeast was locally isolated and molecularly identified, then the yielded SLs were characterized by FTIR, 1H NMR and LC-MS/MS spectra. Posteriorly, thirty-two male Wistar rats were randomly divided into four groups; control (oral saline), SLs (200 mg/kg, p.o), DOX (10 mg/kg; i.p.), and SL + DOX (200 mg/kg p.o.,10 mg/kg; i.p., respectively). Liver function tests (LFTs), oxidative stress, inflammatory, apoptosis as well as autophagy markers were investigated.

KEY FINDINGS

SLs were produced with a yield of 49.04% and treatment with SLs improved LFTs, enhanced Nrf2 and suppressed NF-κB, IL-6, IL-1β, p38, caspase 3 and Bax/Bcl2 ratio in addition to promotion of autophagy when compared to DOX group.

SIGNIFICANCE

Our results revealed a novel promising protective effect of SLs against DOX-induced hepatotoxicity in rats.

FBXL5 promotes lipid accumulation in alcoholic fatty liver disease by promoting the ubiquitination and degradation of TFEB

BACKGROUND

Alcoholic fatty liver disease (AFLD) is characterized by abnormal lipid droplet accumulation in liver. Epigenetic regulation plays an important role in the pathogenesis of AFLD. Comprehensive bioinformatics analysis revealed that an E3 ubiquitin ligase, F-box and leucine-rich repeats protein 5 (FBXL5), was significantly upregulated in AFLD mice.

METHODS

The mouse model of AFLD was established by feeding Lieber-DeCarli liquid diet containing ethanol. An in vitro model of AFLD was established by treating HepG2 cells with ethanol (EtOH). The FBXL5 expression was assessed by quantitative real-time PCR (qRT-PCR) and western blotting assays. The levels of triglyceride (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lipid accumulation were analyzed by enzyme-linked immunosorbent assay (ELISA) and Nile red staining.

RESULTS

The FBXL5 expression was markedly up-regulated in in vivo and in vitro models of AFLD compared with controls. Functionally, FBXL5 knockdown alleviated lipid accumulation in EtOH-treated HepG2 cells. Mechanistically, FBXL5 directly interacted with transcription factor EB (TFEB) and accelerated its ubiquitination-mediated degradation. TFEB knockdown reversed the effect of FBXL5 inhibition on decreasing EtOH-induced lipid accumulation.

CONCLUSION

Our data suggest that FBXL5 promotes lipid accumulation in AFLD by promoting the ubiquitination and degradation of TFEB.

Endoplasmic reticulum stress in the pathogenesis of alcoholic liver disease

The endoplasmic reticulum (ER) plays a pivotal role in protein synthesis, folding, and modification. Under stress conditions such as oxidative stress and inflammation, the ER can become overwhelmed, leading to an accumulation of misfolded proteins and ensuing ER stress. This triggers the unfolded protein response (UPR) designed to restore ER homeostasis. Alcoholic liver disease (ALD), a spectrum disorder resulting from chronic alcohol consumption, encompasses conditions from fatty liver and alcoholic hepatitis to cirrhosis. Metabolites of alcohol can incite oxidative stress and inflammation in hepatic cells, instigating ER stress. Prolonged alcohol exposure further disrupts protein homeostasis, exacerbating ER stress which can lead to irreversible hepatocellular damage and ALD progression. Elucidating the contribution of ER stress to ALD pathogenesis may pave the way for innovative therapeutic interventions. This review delves into ER stress, its basic signaling pathways, and its role in the alcoholic liver injury.

Serum protein biomarkers for HCC risk prediction in HIV/HBV co-infected people: a clinical proteomic study using mass spectrometry

Background

HBV coinfection is frequent in people living with HIV (PLWH) and is the leading cause of hepatocellular carcinoma (HCC). While risk prediction methods for HCC in patients with HBV monoinfection have been proposed, suitable biomarkers for early diagnosis of HCC in PLWH remain uncommon.

Methods

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to examine serum protein alterations in HCC and non-HCC patients with HIV and HBV co-infection. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Disease Ontology (DO) enrichment analysis were performed on the differentially expressed proteins (DEPs). The risk prediction model was created using five-cross-validation and LASSO regression to filter core DEPs.

Results

A total of 124 DEPs were discovered, with 95 proteins up-regulated and 29 proteins down-regulated. Extracellular matrix organization and membrane component were the DEPs that were most abundant in the categories of biological processes (BP) and cellular components (CC). Proteoglycans in cancer were one of the top three DEPs primarily enriched in the KEGG pathway, and 60.0% of DEPs were linked to various neoplasms in terms of DO enrichment. Eleven proteins, including GAPR1, PLTP, CLASP2, IGHV1-69D, IGLV5-45, A2M, VNN1, KLK11, ANPEP, DPP4 and HYI, were chosen as the core DEPs, and a nomogram was created to predict HCC risk.

Conclusion

In HIV/HBV patients with HCC, several differential proteins can be detected in plasma by mass spectrometry, which can be used as screening markers for early diagnosis and risk prediction of HCC. Monitoring protease expression differences can help in the diagnosis and prognosis of HCC.

Mechanisms of Lipid Droplet Accumulation in Steatotic Liver Diseases

The steatotic diseases of metabolic dysfunction-associated steatotic liver disease (MASLD), alcohol-associated liver disease (ALD), and chronic hepatitis C (HCV) account for the majority of liver disease prevalence, morbidity, and mortality worldwide. While these diseases have distinct pathogenic and clinical features, dysregulated lipid droplet (LD) organelle biology represents a convergence of pathogenesis in all three. With increasing understanding of hepatocyte LD biology, we now understand the roles of LD proteins involved in these diseases but also how genetics modulate LD biology to either exacerbate or protect against the phenotypes associated with steatotic liver diseases. Here, we review the history of the LD organelle and its biogenesis and catabolism. We also review how this organelle is critical not only for the steatotic phenotype of liver diseases but also for their advanced phenotypes. Finally, we summarize the latest attempts and challenges of leveraging LD biology for therapeutic gain in steatotic diseases. In conclusion, the study of dysregulated LD biology may lead to novel therapeutics for the prevention of disease progression in the highly prevalent steatotic liver diseases of MASLD, ALD, and HCV.

Design, synthesis, and biological evaluation of carbonyl-hydrazine-1-carboxamide derivatives as anti-hepatic fibrosis agents targeting Nur77

Hepatic fibrosis remains a great challenge clinically. The orphan nuclear receptor Nur77 is recently suggested as the critical regulator of transforming growth factor-β (TGF-β) signaling, which plays a central role in multi-organic fibrosis. Herein, we optimized our previously reported Nur77-targeted compound 9 h for attempting to develop effective and safe anti-hepatic fibrosis agents. The critical pharmacophore scaffold of pyridine-carbonyl-hydrazine-1-carboxamide was retained, while the naphthalene ring was replaced with an aromatic ring containing pyridyl or indole groups. Four series of derivatives were thus generated, among which the compound 16f had excellent binding activity toward Nur77-LBD (KD = 470 nM) with the best inhibitory activity against the TGF- β 1 activation of hepatic stellate cells (HSCs) and low cytotoxicity to normal mice liver AML-12 cells (IC50 > 80 μM). In mice, 16f displayed potent activity against CCl4-induced liver fibrosis with improved liver function. Mechanistically, 16f-mediated inactivation of HSC and suppression of liver fibrosis were associated with its enhancement of autophagic flux in a Nur77-dependent manner. Together, 16f was identified as a potential anti-liver fibrosis agent. Our study suggests that Nur77 may serve as a critical anti-hepatic fibrosis target.

Liraglutide ameliorates hepatic steatosis via retinoic acid receptor-related orphan receptor α-mediated autophagy pathway

Liraglutide, an analog of human glucagon-like peptide-1 (GLP-1), has been found to improve hepatic steatosis in clinical practice. However, the underlying mechanism remains to be fully defined. Increasing evidence suggests that retinoic acid receptor-related orphan receptor α (RORα) is involved in hepatic lipid accumulation. In the current study, we investigated whether the ameliorating impact of liraglutide on lipid-induced hepatic steatosis is dependent on RORα activity and examined the underlying mechanisms. Cre-loxP-mediated, liver-specific Rorα knockout (Rora LKO) mice, and littermate controls with a Roraloxp/loxp genotype were established. The effects of liraglutide on lipid accumulation were evaluated in mice challenged with a high-fat diet (HFD) for 12 weeks. Moreover, mouse AML12 hepatocytes expressing small interfering RNA (siRNA) of Rora were exposed to palmitic acid to explore the pharmacological mechanism of liraglutide. The results showed that liraglutide treatment significantly alleviated HFD-induced liver steatosis, marked by reduced liver weight and triglyceride accumulation, improved glucose tolerance and serum levels of lipid profiles and aminotransferase. Consistently, liraglutide also ameliorated lipid deposits in a steatotic hepatocyte model in vitro. In addition, liraglutide treatment reversed the HFD-induced downregulation of Rora expression and autophagic activity in mouse liver tissues. However, the beneficial effect of liraglutide on hepatic steatosis was not observed in Rora LKO mice. Mechanistically, the ablation of Rorα in hepatocytes diminished liraglutide-induced autophagosome formation and the fusion of autophagosomes and lysosomes, resulting in weakened autophagic flux activation. Thus, our findings suggest that RORα is essential for the beneficial impact of liraglutide on lipid deposition in hepatocytes and regulates autophagic activity in the underlying mechanism.

SQSTM1/p62 and Hepatic Mallory-Denk Body Formation in Alcohol-Associated Liver Disease

Sequestosome 1 (SQSTM1/p62; hereafter p62) is an autophagy receptor protein for selective autophagy primarily due to its direct interaction with the microtubule light chain 3 protein that specifically localizes on autophagosome membranes. As a result, impaired autophagy leads to the accumulation of p62. p62 is also a common component of many human liver disease-related cellular inclusion bodies, such as Mallory-Denk bodies, intracytoplasmic hyaline bodies, α1-antitrypsin aggregates, as well as p62 bodies and condensates. p62 also acts as an intracellular signaling hub, and it involves multiple signaling pathways, including nuclear factor erythroid 2-related factor 2, NF-κB, and the mechanistic target of rapamycin, which are critical for oxidative stress, inflammation, cell survival, metabolism, and liver tumorigenesis. This review discusses the recent insights of p62 in protein quality control, including the role of p62 in the formation and degradation of p62 stress granules and protein aggregates as well as regulation of multiple signaling pathways in the pathogenesis of alcohol-associated liver disease.

Ajugol's upregulation of TFEB-mediated autophagy alleviates endoplasmic reticulum stress in chondrocytes and retards osteoarthritis progression in a mouse model

BACKGROUND

Osteoarthritis (OA), a degenerative disease with a high global prevalence, is characterized by the degradation of the extracellular matrix (ECM) and the apoptosis of chondrocytes. Ajugol, a extract derived from the herb Rehmannia glutinosa, has not yet been investigated for its potential in modulating the development of OA.

METHODS

We employed techniques such as western blotting, immunofluorescence, immunohistochemistry, X-ray imaging, HE staining, and SO staining to provide biological evidence supporting the role of Ajugol as a potential therapeutic agent for modulating OA. Furthermore, in an in vivo experiment, intra-peritoneal injection of 50 mg/kg Ajugol effectively mitigated the progression of OA following destabilization of the medial meniscus (DMM) surgery.

RESULTS

Our findings revealed that treatment with 50 μM Ajugol activated TFEB-mediated autophagy, alleviating ER stress-induced chondrocyte apoptosis and ECM degradation caused by TBHP. Furthermore, in an in vivo experiment, intra-peritoneal injection of 50 mg/kg Ajugol effectively mitigated the progression of OA following destabilization of the medial meniscus (DMM) surgery.

CONCLUSION

These results provide compelling biological evidence supporting the role of Ajugol as a potential therapeutic agent for modulating OA by activating autophagy and attenuating ER stress-induced cell death and ECM degradation. The promising in vivo results further suggest the potential of Ajugol as a treatment strategy for OA progression.

Dissecting the multifaced function of transcription factor EB (TFEB) in human diseases: From molecular mechanism to pharmacological modulation

The transcription factor EB (TFEB) is a transcription factor of the MiT/TFE family that translocations from the cytoplasm to the nucleus in response to various stimuli, including lysosomal stress and nutrient starvation. By activating genes involved in lysosomal function, autophagy, and lipid metabolism, TFEB plays a crucial role in maintaining cellular homeostasis. Dysregulation of TFEB has been implicated in various diseases, including cancer, neurodegenerative diseases, metabolic diseases, cardiovascular diseases, infectious diseases, and inflammatory diseases. Therefore, modulating TFEB activity with agonists or inhibitors may have therapeutic potential. In this review, we reviewed the recently discovered regulatory mechanisms of TFEB and their impact on human diseases. Additionally, we also summarize the existing TFEB inhibitors and agonists (targeted and non-targeted) and discuss unresolved issues and future research directions in the field. In summary, this review sheds light on the crucial role of TFEB, which may pave the way for its translation from basic research to practical applications, bringing us closer to realizing the full potential of TFEB in various fields.