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

Inhibiting autophagy enhances idarubicin chemosensitivity and induces immune escape in FAT1-low-expressing AML cells

OBJECTIVE

Both Autophagy and FAT atypical cadherin 1 (FAT1) regulates the chemosensitivity and immune escape of tumour cells. Our previous paper showed that FAT1 decreased acute myeloid leukemia (AML) autophagy by inhibiting the TGFβ-Smad2/3 pathway. This study builds upon our previous paper and aims to explore whether FAT1-inhibited autophagy is involved in regulating chemosensitivity and immune escape in AML.

METHODS

We validated the inhibitory effect of FAT1 on AML autophagy through western blot, qPCR, and luciferase reporter assays. In addition, we explored the effect of FAT1-inhibited autophagy on idarubicin (IDA) sensitivity and AML immune escape through caspase-3 activity analysis, trypan blue exclusion assays, and flow cytometry.

RESULTS

We demonstrated for the first time that the autophagy inhibitor chloroquine (CQ) enhances the cytotoxic effect of IDA on FAT1-low-expressing (FAT1-L) AML cells. We also found that CQ weakened CD8+ T cell infiltration in FAT1-L AML cells. Further research revealed that CQ upregulated PD-L1 protein levels by decreasing its autophagic degradation and that the PD-L1 inhibitor atezolizumab reversed the decrease in CD8+ T cell infiltration caused by CQ in FAT1-L AML cells. In addition, we found that FAT1 decreased autophagy related 10 (ATG10) transcription, leading to decreased AML autophagy.

CONCLUSIONS

These results revealed that in FAT1-L AML cells, inhibiting autophagy by CQ enhances the cytotoxic effect of IDA, but leads to immune escape, resulting in AML recurrence. Our study supports the use of a combination of autophagy and PD-L1 inhibitors with IDA to increase the cytotoxic effect of IDA while inhibiting AML recurrence.

Rosmarinic acid-mediated downregulation of RIG-I and p62 in microglia confers resistance to Japanese encephalitis virus-induced inflammation

BACKGROUND

Japanese encephalitis virus (JEV) is a mosquito-borne zoonotic pathogen that causes encephalitis in humans and reproductive failure in pigs. The transmission of JEV between humans and animals poses a significant public health threat and results in substantial economic losses. Excessive inflammation in the central nervous system of JEV-infected patients is a major cause of mortality and disability. Rosmarinic acid (RA), a polyhydroxyphenolic compound isolated from medicinal herbs, has been preliminarily shown to possess anti-inflammatory properties and significantly inhibit JEV-induced neuroinflammation in mice.

RESULTS

This study investigated the antiviral capacity and potential mechanisms of RA in JEV-infected cells. The results demonstrated that RA could inhibit JEV replication in vitro. Furthermore, the expression levels of inflammatory cytokines (including IL-6, IL-1β, CCL-2, and TNF-α), membrane receptors (including RIG-I, TLR3, TLR4, TLR7, and TLR8), NF-κB complex and p62/SQSTM1 were assessed using qPCR, ELISA, and Western blot, respectively. The findings indicated that RA significantly suppressed the expression of IL-6, IL-1α, TNF-α, and CCL-2 in JEV-infected BV-2 cells in a dose-dependent manner. Additionally, RA treatment downregulated the expression levels of RIG-I and p62, while p62 silencing inhibited the upregulation of inflammatory cytokines in JEV-infected BV-2 cells.

CONCLUSION

Our present study highlights the important role of RA-mediated reduction of RIG-I and p62 in microglia, conferring resistance to Japanese encephalitis virus-induced inflammation.

Melatonin Attenuates Ferritinophagy/Ferroptosis by Acting on Autophagy in the Liver of an Autistic Mouse Model BTBR T+Itpr3tf/J

Autism spectrum disorders (ASDs) are a pool of neurodevelopment disorders in which social impairment is the main symptom. Presently, there are no definitive medications to cure the symptoms but the therapeutic strategies that are taken ameliorate them. The purpose of this study was to investigate the effects of melatonin (MLT) in treating ASDs using an autistic mouse model BTBR T+Itpr3tf/J (BTBR). We evaluated the hepatic cytoarchitecture and some markers of autophagy, ferritinophagy/ferroptosis, in BTBR mice treated and not-treated with MLT. The hepatic morphology and the autophagy and ferritinophagy/ferroptosis pathways were analyzed by histological, immunohistochemical, and Western blotting techniques. We studied p62 and microtubule-associated protein 1 light chain 3 B (LC3B) for evaluating the autophagy; nuclear receptor co-activator 4 (NCOA4) and long-chain-coenzyme synthase (ACSL4) for monitoring ferritinophagy/ferroptosis. The liver of BTBR mice revealed that the hepatocytes showed many cytoplasmic inclusions recognized as Mallory-Denk bodies (MDBs); the expression and levels of p62 and LC3B were downregulated, whereas ACSL4 and NCOA4 were upregulated, as compared to control animals. MLT administration to BTBR mice ameliorated liver damage and reduced the impairment of autophagy and ferritinophagy/ferroptosis. In conclusion, we observed that MLT alleviates liver damage in BTBR mice by improving the degradation of intracellular MDBs, promoting autophagy, and suppressing ferritinophagy/ferroptosis.

VPS4A is the selective receptor for lipophagy in mice and humans

Lipophagy is a ubiquitous mechanism for degradation of lipid droplets (LDs) in lysosomes. Autophagy receptors selectively target organelles for lysosomal degradation. The selective receptor for lipophagy remains elusive. Using mouse liver phosphoproteomics and human liver transcriptomics, we identify vacuolar-protein-sorting-associated protein 4A (VPS4A), a member of a large family AAA+ ATPases, as a selective receptor for lipophagy. We show that phosphorylation of VPS4A on Ser95,97 and its localization to LDs in response to fasting drives lipophagy. Imaging/three-dimensional (3D) reconstruction and biochemical analyses reveal the concomitant degradation of VPS4A and LDs in lysosomes in an autophagy-gene-7-sensitive manner. Either silencing VPS4A or targeting VPS4AS95,S97 phosphorylation or VPS4A binding to LDs or LC3 blocks lipophagy without affecting other forms of selective autophagy. Finally, VPS4A levels and markers of lipophagy are markedly reduced in human steatotic livers-revealing a fundamental role of VPS4A as the lipophagy receptor in mice and humans.

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.

Selenium restored mitophagic flux to alleviate cadmium-induced hepatotoxicity by inhibiting excessive GPER1-mediated mitophagy activation

Cadmium (Cd) is a common environmental pollutant, while selenium (Se) can ameliorate heavy metal toxicity. Consequently, this study aimed to investigate the protective effects of Se against Cd-induced hepatocyte injury and its underlying mechanisms. To achieve this, we utilized the Dongdagou-Xinglong cohort, BRL3A cell models, and a rat model exposed to Cd and/or Se. The results showed that Se counteracted liver function injury and the decrease in GPER1 levels caused by environmental Cd exposure, and various methods confirmed that Se could protect against Cd-induced hepatotoxicity both in vivo and in vitro. Mechanistically, Cd caused excessive mitophagy activation, evidenced by the colocalization of LC3B, PINK1, Parkin, P62, and TOMM20. Transfection of BRL3A cells with mt-keima adenovirus indicated that Cd inhibited autophagosome-lysosome fusion, thereby impeding mitophagic flux. Importantly, G1, a specific agonist of GPER1, mitigated Cd-induced mitophagy overactivation and hepatocyte toxicity, whereas G15 exacerbates these effects. Notably, Se supplementation attenuated Cd-induced GPER1 protein reduction and excessive mitophagy activation while facilitating autophagosome-lysosome fusion, thereby restoring mitophagic flux. In conclusion, this study proposed a novel mechanism whereby Se alleviated GPER1-mediated mitophagy and promoted autophagosome-lysosome fusion, thus restoring Cd-induced mitophagic flux damage, and preventing hepatocyte injury.

The role of LncRNA-mediated autophagy in cancer progression

Long non-coding RNAs (lncRNAs) are a sort of transcripts that are more than 200 nucleotides in length. In recent years, many studies have revealed the modulatory role of lncRNAs in cancer. Typically, lncRNAs are linked to a variety of essential events, such as apoptosis, cellular proliferation, and the invasion of malignant cells. Simultaneously, autophagy, an essential intracellular degradation mechanism in eukaryotic cells, is activated to respond to multiple stressful circumstances, for example, nutrient scarcity, accumulation of abnormal proteins, and organelle damage. Autophagy plays both suppressive and promoting roles in cancer. Increasingly, studies have unveiled how dysregulated lncRNAs expression can disrupt autophagic balance, thereby contributing to cancer progression. Consequently, exploring the interplay between lncRNAs and autophagy holds promising implications for clinical research. In this manuscript, we methodically compiled the advances in the molecular mechanisms of lncRNAs and autophagy and briefly summarized the implications of the lncRNA-mediated autophagy axis.

Ferritinophagy Mediated by Oxidative Stress-Driven Mitochondrial Damage Is Involved in the Polystyrene Nanoparticles-Induced Ferroptosis of Lung Injury

Nanoplastics are a common type of contaminant in the air. However, no investigations have focused on the toxic mechanism of lung injury induced by nanoplastic exposure. In the present study, polystyrene nanoplastics (PS-NPs) caused ferroptosis in lung epithelial cells, which could be alleviated by ferrostatin-1, deferoxamine, and N-acetylcysteine. Further investigation found that PS-NPs disturbed mitochondrial structure and function and triggered autophagy. Mechanistically, oxidative stress-derived mitochondrial damage contributed to ferroptosis, and autophagy-dependent ferritinophagy was a pivotal intermediate link, resulting in ferritin degradation and iron ion release. Furthermore, inhibition of ferroptosis using ferrostatin-1 alleviated pulmonary and systemic toxicity to reverse the mouse lung injury induced by PS-NPs inhalation. Most importantly, the lung-on-a-chip was further used to clarify the role of ferroptosis in the PS-NPs-induced lung injury by visualizing the ferroptosis, oxidative stress, and alveolar-capillary barrier dysfunction at the organ level. In summary, our study indicated that ferroptosis was an important mechanism for nanoplastics-induced lung injury through different lung cells, mouse inhalation models, and three-dimensional-based lung-on-a-chip, providing an insightful reference for pulmonary toxicity assessment of nanoplastics.