Palmitoylation prevents sustained inflammation by limiting NLRP3 inflammasome activation through chaperone-mediated autophagy

Unraveling the potential of neuroinflammation and autophagy in schizophrenia

Schizophrenia (SCZ) is a complex and chronic psychiatric disorder that affects a significant proportion of the global population. Although the precise etiology of SCZ remains uncertain, recent studies have underscored the involvement of neuroinflammation and autophagy in its pathogenesis. Neuroinflammation, characterized by hyperactivated microglia and markedly elevated pro-inflammatory cytokines, has been observed in postmortem brain tissues of SCZ patients and is closely associated with disease severity. Autophagy, a cellular process responsible for eliminating damaged components and maintaining cellular homeostasis, is believed to play a pivotal role in neuronal health and the onset of SCZ. This review explores the roles and underlying mechanisms of neuroinflammation and autophagy in SCZ, with a particular focus on their intricate interplay. Additionally, we provide an overview of potential therapeutic strategies aimed at modulating neuroinflammation and autophagy, including nutritional interventions, anti-inflammatory drugs, antipsychotics, and plant-derived natural compounds. The review also addresses the dual effects of antipsychotics on autophagy. Our objective is to translate these insights into clinical practice, expanding the therapeutic options available to improve the overall health and well-being of individuals with SCZ.

Chaperone-mediated autophagy directs a dual mechanism to balance premature senescence and senolysis to prevent intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a progressive and dynamic process in which the senescence-associated secretory phenotype (SASP) of nucleus pulposus cells (NPC) plays a significant role. While impaired chaperone-mediated autophagy (CMA) has been associated with inflammation and cellular senescence, its specific involvement in the self-perpetuating feedback loop of NPC senescence remains poorly understood. Through LAMP2A knockout in NPC, we identified a significant upregulation of DYRK1A, a core mediator of premature senescence in Down syndrome. Subsequent validation established DYRK1A as the critical driver of premature senescence in CMA-deficient NPC. Combinatorial transcription factor analysis revealed that under IL1B stimulation or CMA inhibition, elevated DYRK1A promoted FOXC1 phosphorylation and nuclear translocation, initiating transcriptional activation of cell cycle arrest. Intriguingly, CMA impairment concurrently enhanced glutamine metabolic flux in senescent NPC, thereby augmenting their survival fitness. Transcriptomic profiling demonstrated that CMA reactivation in senescent NPC facilitated fate transition from senescence to apoptosis, mediated by decreased glutamine flux via GLUL degradation. Therefore, CMA exerts protective effects against IDD by maintaining equilibrium between premature senescence and senolysis. This study elucidates CMA's regulatory role in SASP-mediated senescence amplification circuits, providing novel therapeutic insights for IDD and other age-related pathologies.

The dual role of chaperone-mediated autophagy in the response and resistance to cancer immunotherapy

Cancer immunotherapy has become a revolutionary strategy in oncology, utilizing the host immune system to fight malignancies. Notwithstanding major progress, obstacles such as immune evasion by tumors and the development of resistance still remain. This manuscript examines the function of chaperone-mediated autophagy (CMA) in cancer biology, focusing on its effects on tumor immunotherapy response and resistance. CMA is a selective degradation mechanism for cytosolic proteins, which is crucial for sustaining cellular homeostasis and regulating immune responses. By degrading specific proteins, CMA can either facilitate tumor progression in stressful conditions, or promote tumor suppression by removing oncogenic factors. This double-edged sword highlights the complexity of CMA in cancer progression and its possible effect on treatment results. Here we clarify the molecular mechanisms by which CMA can regulate the immune response and its possible role as a therapeutic target for improving the effectiveness of cancer immunotherapy.

Updated insights into the molecular networks for NLRP3 inflammasome activation

Over the past decade, significant advances have been made in our understanding of how NACHT-, leucine-rich-repeat-, and pyrin domain-containing protein 3 (NLRP3) inflammasomes are activated. These findings provide detailed insights into the transcriptional and posttranslational regulatory processes, the structural-functional relationship of the activation processes, and the spatiotemporal dynamics of NLRP3 activation. Notably, the multifaceted mechanisms underlying the licensing of NLRP3 inflammasome activation constitute a focal point of intense research. Extensive research has revealed the interactions of NLRP3 and its inflammasome components with partner molecules in terms of positive and negative regulation. In this Review, we provide the current understanding of the complex molecular networks that play pivotal roles in regulating NLRP3 inflammasome priming, licensing and assembly. In addition, we highlight the intricate and interconnected mechanisms involved in the activation of the NLRP3 inflammasome and the associated regulatory pathways. Furthermore, we discuss recent advances in the development of therapeutic strategies targeting the NLRP3 inflammasome to identify potential therapeutics for NLRP3-associated inflammatory diseases. As research continues to uncover the intricacies of the molecular networks governing NLRP3 activation, novel approaches for therapeutic interventions against NLRP3-related pathologies are emerging.

Palmitoylation in cardiovascular diseases: Molecular mechanism and therapeutic potential

Cardiovascular disease is one of the leading causes of mortality worldwide, and involves complex pathophysiological mechanisms that encompass various biological processes and molecular pathways. Post-translational modifications of proteins play crucial roles in the occurrence and progression of cardiovascular diseases, among which palmitoylation is particularly important. Various proteins associated with cardiovascular diseases can be palmitoylated to enhance the hydrophobicity of their molecular subdomains. This lipidation can significantly affect some pathophysiological processes, such as metabolism, inflammation by altering protein stability, localization, and signal transduction. In this review, we narratively summarize recent advances in the palmitoylation of proteins related to cardiovascular diseases and discuss its potential as a therapeutic target.

Mechanism of S-Palmitoylation in Polystyrene Nanoplastics-Induced Macrophage Cuproptosis Contributing to Emphysema through Alveolar Epithelial Cell Pyroptosis

More than microplastics, nanoplastics may pose a greater toxic effect on humans due to their unique physicochemical properties. Currently, research on lung diseases caused by respiratory exposure to nanoplastics is scarce, with epigenetic mechanisms warranting further investigation. In the present study, we exposed rats to polystyrene nanoplastics (PS-NPs) via an oral-nasal exposure system and found that PS-NPs exposure resulted in emphysema. Mechanistically, PS-NPs entered macrophages and competitively bound to sigma nonopioid intracellular receptor 1 (SIGMAR1), leading to an increase in free zDHHC palmitoyltransferase 14 (zDHHC14). This, in turn, caused elevated palmitoylation of solute carrier family 31 member 1 (SLC31A1) in macrophages, inhibiting its ubiquitination and degradation, thereby enhancing SLC31A1 expression. The increased expression of SLC31A1 promoted cuproptosis of macrophages and elevated tumor necrosis factor-α (TNF-α) secretion, which activated the NLR family pyrin domain containing 3/matrix metallopeptidase 9 (NLRP3/MMP-9) pathway in alveolar epithelial cells (AECs). This process mediated pyroptosis and degradation of extracellular matrix (ECM), resulting in the destruction of alveolar structure and development of emphysema. The findings demonstrate a previously unknown molecular mechanism by which PS-NPs induce emphysema. The findings have implications for the prevention and treatment of respiratory system damage caused by nanoparticles.

The role of palmitoylation modifications in the regulation of bone cell function, bone homeostasis, and osteoporosis

Osteoporosis a is a metabolic bone disease caused by an imbalance in bone homeostasis, which is regulated by osteoblasts and osteoclasts. Protein palmitoylation modification is a post-translational modification that affects protein function, localization, and targeting by attaching palmitoyl groups to specific amino acid residues of proteins. Recent studies have shown that protein palmitoylation is involved in the regulation of osteoclast overproduction, osteoblast migration, osteogenic differentiation, dysfunctional autophagy, and endocrine hormone membrane receptors in osteoporosis. Exactly to what extent palmitoylation modifications can regulate osteoporosis, and whether palmitoylation inhibition can delay osteoporosis, is a key question that needs to be investigated urgently. In this review, we observed that palmitoylation modifications act mainly through two target cells - osteoblasts and osteoclasts - and that the targets of palmitoylation modifications are focused on plasma membrane proteins or cytosolic proteins of the target cells, which tend to assume the role of receiving extracellular signals. We also noted that different palmitoyl transferases acting on different substrate proteins exert conflicting regulation of osteoblast function. We concluded that the regulation of osteocyte function, bone homeostasis, and osteoporosis by palmitoylation modifications is multidimensional, diverse, and interconnected. Perfecting the palmitoylation modification network can enhance our ability to utilize post-translational modifications to resist osteoporosis and lay the foundation for targeting palmitoyl transferases to treat osteoporosis in the future.

Palmitoylated COX-2Cys555 reprogrammed mitochondrial metabolism in pyroptotic inflammatory injury in patients with post-acute COVID-19 syndrome

INTRODUCTION

The complex interplay between protein palmitoylation, mitochondrial dynamics, and inflammatory responses plays a pivotal role in respiratory diseases. One significant feature of post-acute coronavirus disease 2019 (COVID-19) syndrome (PACS) is the occurrence of a storm of inflammatory cytokines related to the NOD-like receptor protein 3 (NLRP3). However, the specific mechanisms via which palmitoylation affects mitochondrial function and its impact on the NLRP3 inflammasome under pathological respiratory conditions remain to be elucidated.

OBJECTIVE

This study aimed to investigate how protein palmitoylation influences inflammatory responses and mitochondrial dynamics in respiratory diseases, such as those induced by the SARS-CoV-2 spike S protein in PACS, thereby providing a therapeutic target for inflammatory lung injury.

METHODS

In vivo experiments were conducted using AdV5-pADM-CMV-COVID-19-S (AdV5-S) nasal drip-treated C57BL/6 mice to assess NLRP3 inflammasome activation and inflammatory response. In vitro experiments were performed using pCMV-S-transfected human lung epithelial BEAS-2B cells to analyze the effects of DHHC5-mediated palmitoylation of cyclooxygenase-2 (COX-2) at cysteine 555 (COX-2Cys555) on mitochondrial metabolism and NLRP3 inflammasome activation.

RESULTS

Palmitoylation of COX-2Cys555 enhanced its interaction with hexokinase 2 (HK2) to regulate mitochondrial metabolic reprogramming, leading to NLRP3 inflammasome activation and pyroptosis. Pharmacological and genetic suppression of palmitoylation diminished the mitochondrial localization of palmitoylated COX-2 and its interaction with HK2, thereby reducing mitochondrial metabolic reprogramming. Furthermore, genetic intervention targeting DHHC5 (shDhhc5) alleviated NLRP3 activation and pyroptosis, mitigating the chronic inflammatory damage associated with PACS.

CONCLUSION

This study highlights the regulatory role of COX-2Cys555 palmitoylation in mitochondrial metabolism and lung inflammatory injury, and suggests potential therapeutic targets to combat respiratory pathogenesis linked to palmitoylated COX-2.

Rutin ameliorates LPS-induced acute lung injury in mice by inhibiting the cGAS-STING-NLRP3 signaling pathway

Introduction

Acute lung injury (ALI) and its severe form, acute respiratory distress syndrome (ARDS), represent critical respiratory failures with high mortality rates and limited treatment options. While the flavonoid rutin exhibits documented anti-inflammatory and antioxidant properties, its therapeutic mechanisms in ALI/ARDS remain unclear. This study investigated rutin's efficacy against lipopolysaccharide (LPS)-induced ALI in mice, with a mechanistic focus on the cGAS-STING pathway and NLRP3 inflammasome activation.

Methods

Male C57BL/6 mice were divided into Vehicle control, LPS induction, LPS + rutin co-treatment, and Rutin monotherapy groups. ALI was induced by intratracheal LPS challenge, and rutin was administered via gavage. Proteomics analysis, histological evaluation, immunohistochemistry, TUNEL staining, immunofluorescence, RT-qPCR, western blot, ELISA, and oxidative stress assays were performed to assess the effects of rutin on ARDS.

Results

The proteomic profiling of lung tissues from LPS-challenged mice identified significant dysregulation of proteins integral to the cGAS-STING cascade and pyroptotic processes. Gene ontology and KEGG pathway analyses underscored the pivotal role of immune and inflammatory responses in ALI, particularly in cytosolic DNA-sensing and NOD-like receptor signaling pathways. Rutin administration significantly alleviated LPS-induced lung injury, reducing oxidative stress, apoptosis, and proinflammatory cytokine levels (IL-6, IL-1β, TNF-α). Mechanistically, rutin demonstrated dual suppression: 1) inhibiting cGAS-STING activation through decreased expression of cGAS, STING, and phosphorylation of TBK1/IRF3 (P<0.05), and 2) attenuating NLRP3-mediated pyroptosis via downregulation of NLRP3-ASC-caspase1-GSDMD signaling (P<0.05). Pharmacological STING inhibition (C-176) validated the cGAS-STING-NLRP3 regulatory hierarchy in ALI pathogenesis.

Conclusion

These findings elucidate rutin's novel therapeutic mechanism through coordinated suppression of the cGAS-STING-NLRP3 axis, positioning it as a promising candidate for ALI/ARDS intervention.

Protein lipidation in the tumor microenvironment: enzymology, signaling pathways, and therapeutics

Protein lipidation is a pivotal post-translational modification that increases protein hydrophobicity and influences their function, localization, and interaction network. Emerging evidence has shown significant roles of lipidation in the tumor microenvironment (TME). However, a comprehensive review of this topic is lacking. In this review, we present an integrated and in-depth literature review of protein lipidation in the context of the TME. Specifically, we focus on three major lipidation modifications: S-prenylation, S-palmitoylation, and N-myristoylation. We emphasize how these modifications affect oncogenic signaling pathways and the complex interplay between tumor cells and the surrounding stromal and immune cells. Furthermore, we explore the therapeutic potential of targeting lipidation mechanisms in cancer treatment and discuss prospects for developing novel anticancer strategies that disrupt lipidation-dependent signaling pathways. By bridging protein lipidation with the dynamics of the TME, our review provides novel insights into the complex relationship between them that drives tumor initiation and progression.

S-palmitoylation modulates ATG2-dependent non-vesicular lipid transport during starvation-induced autophagy

Lipid transfer proteins mediate the non-vesicular transport of lipids at membrane contact sites to regulate the lipid composition of organelle membranes. Despite significant recent advances in our understanding of the structural basis for lipid transfer, its functional regulation remains unclear. In this study, we report that S-palmitoylation modulates the cellular function of ATG2, a rod-like lipid transfer protein responsible for transporting phospholipids from the endoplasmic reticulum (ER) to phagophores during autophagosome formation. During starvation-induced autophagy, ATG2A undergoes depalmitoylation as the balance between ZDHHC11-mediated palmitoylation and APT1-mediated depalmitoylation. Inhibition of ATG2A depalmitoylation leads to impaired autophagosome formation and disrupted autophagic flux. Further, in cell and in vitro analyses demonstrate that S-palmitoylation at the C-terminus of ATG2A anchors the C-terminus to the ER. Depalmitoylation detaches the C-terminus from the ER membrane, enabling it to interact with phagophores and promoting their growth. These findings elucidate a S-palmitoylation-dependent regulatory mechanism of cellular ATG2, which may represent a broad regulatory strategy for lipid transport mediated by bridge-like transporters within cells.

Palmitoyl-transferase 3 promotes mitochondrial antiviral signaling protein degradation by modulating its ubiquitination

The innate antiviral immunity of humans serves as their first line of defence against viral and microbial illnesses. The retinoic acid-inducible gene I (RIG-I)-like receptor (RLR) signaling pathway requires the mitochondrial antiviral signaling protein (MAVS) to function properly. ZDHHCs, a family of acyltransferases, regulate diverse biological processes via interactions with numerous mammalian proteins and viral proteins. However, the role of ZDHHCs in antiviral innate immunity against RNA viruses remains largely elusive. Here, we show that ZDHHC3 downregulates the RLR signaling pathway. Ectopic ZDHHC3 expression reduces RIG-IN- and SeV-mediated IFN-β promoter activity, IRF3 nuclear transduction, and transcription of the IFN-β and ISG genes. Furthermore, ectopic expression of ZDHHC3 decreases MAVS stability by promoting proteasomal degradation, which can be reversed by MG132 but not CQ. ZDHHC3 interacts with MAVS and promotes its breakdown by increasing K48-linked ubiquitination rather than K63-linked ubiquitination. ZDHHC3 deletion resulted in increased IFN-β promoter activity and transcription of the IFN-β and ISG genes. ZDHHC3 knockdown promotes subsequent antiviral signaling and reduces viral replication, indicating the role of ZDHHC3 in antiviral innate immunity. In addition, the catalytically inactive mutant ZDHHC3 C157S efficiently reversed the IFN-β promoter activity produced by RIG-IN, which was consistent with the results of 2-BP treatment. Collectively, these data show that ZDHHC3 inhibits the RNA virus-triggered signaling cascade by targeting MAVS and provides new insights into the role of ZDHHC3 in antiviral innate immunity.

Zinc finger DHHC-type palmitoyltransferase 13-mediated S-palmitoylation of GNA13 from Sertoli cell-derived extracellular vesicles inhibits autophagy in spermatogonial stem cells

Extracellular vesicles (EVs) originating from testicular somatic cells act as pivotal intermediaries in cell signaling crosstalk between spermatogenic cells and the testicular microenvironment. The intricate balance between palmitoylation and depalmitoylation governs the positioning of protein cargos on the membrane, thereby influencing cellular activities by concentrating these proteins in EVs for delivery to recipient cells. Here, we reveal that GNA13 undergoes specific S-palmitoylation at Cys14 and Cys18 residues in Sertoli cells (SCs), a modification essential for its localization to the plasma membrane. We identify DHHC13, a member of the zinc finger DHHC-type palmitoyltransferase family that catalyzes protein S-palmitoylation, as the enzyme responsible for this critical post-translational modification. Additionally, GNA13 palmitoylation is indispensable for its selective enrichment in EVs emanating from SCs. Intriguingly, we discovered the presence of palmitoylated GNA13 in SC-derived EVs significantly downregulates autophagy levels in spermatogonial stem cells (SSCs), and the inhibition of GNA13 palmitoylation attenuates its interaction with ARHGEF12 which leads to diminished RhoA activity and consequent elevation of autophagy in SSCs. Our results illuminate the crucial role of DHHC13-mediated GNA13 S-palmitoylation in modulating autophagy levels in SSCs through SCs-derived EVs, suggesting that PM-GNA13-EV may serve as a potential candidate for further exploration in addressing fertility-related challenges during spermatogenesis.

The role of NLRP3 inflammasome in multiple sclerosis: pathogenesis and pharmacological application

Multiple sclerosis (MS) is widely acknowledged as a chronic inflammatory autoimmune disorder characterized by central nervous system (CNS) demyelination and neurodegeneration. The hyperactivation of immune and inflammatory responses is recognized as a pivotal factor contributing to the pathogenesis and progression of MS. Among various immune and inflammatory reactions, researchers have increasingly focused on the inflammasome, a complex of proteins. The initiation and activation of the inflammasome are intricately involved in the onset of MS. Notably, the NLRP3 inflammasome, the most extensively studied member of the inflammasome complex, is closely linked with MS. This review will delve into the roles of the NLRP3 inflammasome in the pathogenesis and progression of MS. Additionally, therapeutic strategies targeting the NLRP3 inflammasome for the treatment of MS, including natural compounds, autophagy regulators, and other small molecular compounds, will be detailed in this review.

Neem leaf extract alleviates LPS/D-GalN induced acute hepatitis in mice through its anti-inflammatory effects and activation of autophagy

Acute hepatitis, characterized by rapid onset and high mortality, can result from infections, toxins, and other factors. However, current treatment options have significant side effects, necessitating further research into alternative therapies. This study investigated the extraction method of neem extract and found that its ethanolic extract effectively reduced mortality and decreased ALT and AST levels in mice serum, improving liver pathology. HPLC analysis identified azadirachtin and nimbolide in the extract. It also downregulated NF-κB, NLRP3, and p62 levels, while upregulating Lc3B and Atg5 levels. Experiments in Atg5 knockout mice showed that the absence of Atg5 weakened the extract's efficacy in reducing liver damage and inflammation and affected the extent of NLRP3 protein downregulation. However, it did not affect the extract's ability to reduce NF-κB. Overall, the ethanolic extract of neem leaves primarily modulates the inflammatory response through the NF-κB signaling pathway. The extract's efficacy in reducing NLRP3 is associated with autophagy. These discoveries offer a new theoretical basis for the role of neem in treating acute hepatitis.

Signal-induced NLRP3 phase separation initiates inflammasome activation

NLRP3 inflammasome is activated by diverse stimuli including infections, intracellular and environmental irritants. How NLRP3 senses these unrelated stimuli and what activates NLRP3 remain unknown. Here we report that signal-dependent NLRP3 phase separation initiated its activation, in which the palmitoyltransferase ZDHHC7-mediated tonic NLRP3 palmitoylation and an IDR region in the FISNA domain of NLRP3 play important roles. Moreover, three conserved hydrophobic residues in the IDR critically mediate multivalent weak interactions. NLRP3-activating stimuli including K+ efflux and NLRP3-interacting molecules imiquimod, palmitate, and cardiolipin all cause NLRP3 conformational change and induce its phase separation and activation in cells and/or in vitro. Surprisingly, amphiphilic molecules like di-alcohols used to inhibit biomolecular phase separation and chemotherapeutic drugs doxorubicin and paclitaxel activate NLRP3 independently of ZDHHC7 by directly inducing NLRP3 phase separation. Mechanistically, amphiphilic molecules decrease the solubility of both palmitoylated and non-palmitoylated NLRP3 to directly induce its phase separation and activation while NLRP3 palmitoylation reduces its solubility to some extent without activation. Therefore, ZDHHC7-mediated NLRP3 palmitoylation in resting cells licenses its activation by lowering the threshold for NLRP3 phase separation in response to any of the diverse stimuli whereas NLRP3 solubility-reducing molecules like di-alcohols and chemotherapeutic drugs activate NLRP3 directly. The signal-induced NLRP3 phase separation likely provides the simplest and most direct mechanistic basis for NLRP3 activation.

Targeting chaperone-mediated autophagy in neurodegenerative diseases: mechanisms and therapeutic potential

The pathological hallmarks of various neurodegenerative diseases including Parkinson's disease and Alzheimer's disease prominently feature the accumulation of misfolded proteins and neuroinflammation. Chaperone-mediated autophagy (CMA) has emerged as a distinct autophagic process that coordinates the lysosomal degradation of specific proteins bearing the pentapeptide motif Lys-Phe-Glu-Arg-Gln (KFERQ), a recognition target for the cytosolic chaperone HSC70. Beyond its role in protein quality control, recent research underscores the intimate interplay between CMA and immune regulation in neurodegeneration. In this review, we illuminate the molecular mechanisms and regulatory pathways governing CMA. We further discuss the potential roles of CMA in maintaining neuronal proteostasis and modulating neuroinflammation mediated by glial cells. Finally, we summarize the recent advancements in CMA modulators, emphasizing the significance of activating CMA for the therapeutic intervention in neurodegenerative diseases.

ATG16L1 restrains macrophage NLRP3 activation and alveolar epithelial cell injury during septic lung injury

BACKGROUND

The lung is the organ most commonly affected by sepsis. Additionally, acute lung injury (ALI) resulting from sepsis is a major cause of death in intensive care units. Macrophages are essential for maintaining normal lung physiological functions and are implicated in various pulmonary diseases. An essential autophagy protein, autophagy-related protein 16-like 1 (ATG16L1), is crucial for the inflammatory activation of macrophages.

METHODS

ATG16L1 expression was measured in lung from mice with sepsis. ALI was induced in myeloid ATG16L1-, NLRP3- and STING-deficient mice by intraperitoneal injection of lipopolysaccharide (LPS, 10 mg/kg). Using immunofluorescence and flow cytometry to assess the inflammatory status of LPS-treated bone marrow-derived macrophages (BMDMs). A co-culture system of BMDMs and MLE-12 cells was established in vitro.

RESULTS

Myeloid ATG16L1-deficient mice exhibited exacerbated septic lung injury and a more intense inflammatory response following LPS treatment. Mechanistically, ATG16L1-deficient macrophages exhibited impaired LC3B lipidation, damaged mitochondria and reactive oxygen species (ROS) accumulation. These abnormalities led to the activation of NOD-like receptor family pyrin domain-containing protein 3 (NLRP3), subsequently enhancing proinflammatory response. Overactivated ATG16L1-deficient macrophages aggravated the damage to alveolar epithelial cells and enhanced the release of double-stranded DNA (dsDNA), thereby promoting STING activation and subsequent NLRP3 activation in macrophages, leading to positive feedback activation of macrophage NLRP3 signalling. Scavenging mitochondrial ROS or inhibiting STING activation effectively suppresses NLRP3 activation in macrophages and alleviates ALI. Furthermore, overexpression of myeloid ATG16L1 limits NLRP3 activation and reduces the severity of ALI.

CONCLUSIONS

Our findings reveal a new role for ATG16L1 in regulating macrophage NLRP3 feedback activation during sepsis, suggesting it as a potential therapeutic target for treating sepsis-induced ALI.

KEY POINTS

Myeloid-specific ATG16L1 deficiency exacerbates sepsis-induced lung injury. ATG16L1-deficient macrophages exhibit impaired LC3B lipidation and ROS accumulation, leading to NLRP3 inflammasome activation. Uncontrolled inflammatory responses in ATG16L1-deficient macrophages aggravate alveolar epithelial cell damage. Alveolar epithelial cells release dsDNA, activating the cGAS-STING-NLRP3 signaling pathway, which subsequently triggers a positive feedback activation of NLRP3. Overexpression of ATG16L1 helps mitigate lung tissue inflammation, offering a novel therapeutic direction for sepsis-induced lung injury.

Artemether relieves liver fibrosis by triggering ferroptosis in hepatic stellate cells via DHHC12-mediated S-palmitoylation of the BECN1 protein

Liver fibrosis, a pivotal stage in chronic liver disease progression, is driven by hepatic stellate cell (HSC) activation. Ferroptosis is a novel form of programmed cell death, which offers therapeutic potential for liver fibrosis. Although artemether (ART) exhibits antifibrotic properties, its mechanisms in liver fibrosis remain unclear. This study aimed to determine the therapeutic effects of ART on liver fibrosis and explore the role of S-palmitoylation in HSC ferroptosis.

METHODS

A mouse model of liver fibrosis was constructed by carbon tetrachloride (CCl4) injection. Transforming growth factor-β (TGF-β) was used for stimulating HSC activation in vitro. Histopathological and serological assays were performed to analyze the therapy effects of ART. Liquid Chromatography/Mass Spectrometry (LC/MS) and acyl-biotinyl exchange (ABE) were used to determine the role of S-palmitoylation in ART-induced HSC ferroptosis. Western blot and Co-Immunoprecipitation (Co-IP) were performed to examine the effects of autophagy in ART-induced HSC ferroptosis through regulating BECN1 S-palmitoylation.

RESULTS

ART ameliorated liver fibrosis by inducing HSC ferroptosis, and the ferroptosis inhibitor ferrostatin-1 (Fer-1) impaired the inhibitory effect of ART. Interestingly, the levels of S-palmitoylation were elevated by upregulating the palmitoyltransferase DHHC12 during ART-induced HSC ferroptosis. DHHC12 knockdown reduced S-palmitoylation levels and impaired ART-mediated HSC ferroptosis. RNA-seq analysis indicated that autophagy activation was essential for ART to induce HSC ferroptosis. 3-methyladenine (3-MA) suppressed autophagy and ART-induced HSC ferroptosis. Importantly, BECN1 S-palmitoylation by DHHC12 drove ART to activate autophagy. DHHC12 bound to the cysteine 21 residue of BECN1, thereby stabilizing the BECN1 protein and facilitating autophagy activation. Mutation of the cysteine 21 residue decreased BECN1 protein stability, autophagy activation and ferroptosis in ART-treated HSCs. In a mouse model of hepatic fibrosis, HSC-specific inhibition of BECN1 S-palmitoylation reversed ART-induced HSC ferroptosis and the improvement of fibrotic liver.

CONCLUSIONS

ART alleviates liver fibrosis by inducing HSC ferroptosis via DHHC12-mediated BECN1 protein S-palmitoylation.

Metabolic reprogramming shapes post-translational modification in macrophages

Polarized macrophages undergo metabolic reprogramming, as well as extensive epigenetic and post-translational modifications (PTMs) switch. Metabolic remodeling and dynamic changes of PTMs lead to timely macrophage response to infection or antigenic stimulation, as well as its transition from a pro-inflammatory to a reparative phenotype. The transformation of metabolites in the microenvironment also determines the PTMs of macrophages. Here we reviewed the current understanding of the altered metabolites of glucose, lipids and amino acids in macrophages shape signaling and metabolism pathway during macrophage polarization via PTMs, and how these metabolites in some macrophage-associated diseases affect disease progression by shaping macrophage PTMs.

Insights into palmitoylation-mediated regulation of inflammasomes

The mammalian inflammasome is crucial for responding to environmental/intrinsic stress, and its regulation remains a significant focus in immune-mediated inflammatory diseases and antitumor immunity. Recent studies highlight a close link between palmitoylation and inflammasome regulation. However, this type of regulation remains elusive but may harbor potential for combating inflammation-driven disorders.

Mechanistic insights into gasdermin-mediated pyroptosis

Pyroptosis, a novel mode of inflammatory cell death, is executed by membrane pore-forming gasdermin (GSDM) family members in response to extracellular or intracellular injury cues and is characterized by a ballooning cell morphology, plasma membrane rupture and the release of inflammatory mediators such as interleukin-1β (IL-1β), IL-18 and high mobility group protein B1 (HMGB1). It is a key effector mechanism for host immune defence and surveillance against invading pathogens and aberrant cancerous cells, and contributes to the onset and pathogenesis of inflammatory and autoimmune diseases. Manipulating the pore-forming activity of GSDMs and pyroptosis could lead to novel therapeutic strategies. In this Review, we discuss the current knowledge regarding how GSDM-mediated pyroptosis is initiated, executed and regulated, its roles in physiological and pathological processes, and the crosstalk between different modes of programmed cell death. We also highlight the development of drugs that target pyroptotic pathways for disease treatment.

Palmitoylation of GPX4 via the targetable ZDHHC8 determines ferroptosis sensitivity and antitumor immunity

Ferroptosis is closely linked with various pathophysiological processes, including aging, neurodegeneration, ischemia-reperfusion injury, viral infection and, notably, cancer progression; however, its post-translational regulatory mechanisms remain incompletely understood. Here we revealed a crucial role of S-palmitoylation in regulating ferroptosis through glutathione peroxidase 4 (GPX4), a pivotal enzyme that mitigates lipid peroxidation. We identified that zinc finger DHHC-domain containing protein 8 (zDHHC8), an S-acyltransferase that is highly expressed in multiple tumors, palmitoylates GPX4 at Cys75. Through small-molecule drug screening, we identified PF-670462, a zDHHC8-specific inhibitor that promotes the degradation of zDHHC8, consequently attenuating GPX4 palmitoylation and enhancing ferroptosis sensitivity. PF-670462 inhibition of zDHHC8 facilitates the CD8+ cytotoxic T cell-induced ferroptosis of tumor cells, thereby improving the efficacy of cancer immunotherapy in a B16-F10 xenograft model. Our findings reveal the prominent role of the zDHHC8-GPX4 axis in regulating ferroptosis and highlight the potential application of zDHHC8 inhibitors in anticancer therapy.

Zika virus inhibits cell death by inhibiting the expression of NLRP3 and A20

Zika virus (ZIKV) is associated with microcephaly in neonates and neurological disorders in adults. Chronic ZIKV infection has been identified in the testes, indicating that the virus can lead to prolonged illness, yet its pathogenesis remains poorly understood. Here, we found that ZIKV infection does not induce significant cell death in mouse macrophages despite the critical role that cell death plays in the antiviral immune response. Furthermore, we discovered that ZIKV infection impairs the activation of the NLPR3-dependent inflammasome and inhibits apoptosis. Consequently, we investigated the regulatory mechanism of the NLRP3 inflammasome and apoptosis in the context of ZIKV infection. Our results revealed significant reductions in the protein expression levels of NLRP3 and A20, attributable to post-transcriptional or translational effects during ZIKV infection. These findings suggest that ZIKV infection may disrupt cell death pathways, leading to its pathogenicity.IMPORTANCEZika virus (ZIKV), first isolated from a nonhuman primate in Africa in 1947, was relatively understudied until 2016. By then, ZIKV had already been reported in more than 20 countries and territories. The infection poses a significant risk, as it is associated with microcephaly in infants and neurological disorders in adults; however, the underlying mechanisms responsible for these severe outcomes remain unclear. In this study, we demonstrate that ZIKV infection significantly reduces the expression of NLRP3 and A20 proteins through post-transcriptional or translational processes, which leads to inhibited cell death. These findings are critical because cell death plays a vital role in the host's antiviral immune response. Our findings highlight how ZIKV infection compromises essential cell death pathways, raising serious concerns about its pathogenesis. A comprehensive understanding of this disruption is vital for developing targeted interventions to mitigate the virus' impact on public health.

FlaA N/C attenuates radiation-induced lung injury by promoting NAIP/NLRC4/ASC inflammasome autophagy and inhibiting pyroptosis

BACKGROUND

Radiation-induced lung injury (RILI) is the most common complication experienced by patients with thoracic tumors after radiotherapy. Among patients receiving thoracic tumor radiotherapy, 14.6-37.2% develop RILI. RILI is characterized by an acute inflammatory response; however, the exact mechanism remains unclear and an ideal drug is still lacking. In this study, we investigated the protective effects of flagellin A with linked C- and N-terminal ends (FlaA N/C) against the development of RILI.

METHODS

Mice and bronchial epithelial cells were exposed to radiation (15 Gy) after FlaA N/C treatment. Lung injury, bronchial epithelial cell injury, and RILI were assessed by histological evaluation in vivo and cell viability and cell death detection in vitro. Pyroptosis was assessed by western blotting (WB), immunofluorescence (IF), and immunohistochemistry (IHC). To explore the molecular mechanisms by which FlaA N/C inhibits RILI, conditional Beclin 1 (Beclin1+/-) and NLR family CARD domain-containing protein 4 (Nlrc4)-knockout (Nlrc4-/-) mice were generated. An autophagy inhibitor was used for in vitro cell assays, and pyroptosis indicators were detected. Data were analyzed using one-way analysis of variance.

RESULTS

FlaA N/C attenuated radiation-induced lung tissue damage, pro-inflammatory cytokine release, and pyroptosis in vivo and cell viability, cell death, and pyroptosis in vitro. Mechanistically, FlaA N/C activated the neuronal apoptosis inhibitory protein (NAIP)/NLRC4/apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) inflammasome, which was then degraded during Beclin 1-mediated autophagy. Deletion of the FlaA N/C D0 domain reversed the inhibitory effect of FlaA N/C on radiation-induced pyroptosis in vivo and in vitro. Similarly, Nlrc4-knockout in vivo or inhibition of autophagy in vitro eliminated the protective effects of FlaA N/C against radiation-induced pyroptosis.

CONCLUSIONS

These results indicate that FlaA N/C attenuates RILI by promoting NAIP/NLRC4/ASC inflammasome autophagy and inhibiting pyroptosis. This study provides a potential approach for RILI intervention.

Chaperone-Mediated Autophagy Reactivation Protects Against Severe Acute Pancreatitis-Associated Liver Injury Through Upregulating Keap1/Nrf2 Signaling Pathway and Inhibiting NLRP3 Inflammasome Activation

Acute liver injury (ALI) is a vital factor in the early progression of severe acute pancreatitis (SAP). It exacerbates systemic inflammation, impairs the liver's capacity to clear inflammatory mediators and cytokines, and contributes to systemic organ dysfunction syndrome (SODS). However, the mechanisms driving SAP-associated liver injury (SAP-ALI) are poorly understood, and effective therapeutic options remain limited. Chaperone-mediated autophagy (CMA), a selective form of autophagy, plays an essential role in reducing inflammation and oxidative stress by clearing damaged or dysfunctional proteins. This study examines the role of CMA in SAP-ALI and evaluates its therapeutic potential. In a sodium taurocholate-induced SAP-ALI rat model, CMA dysfunction was observed, characterized by reduced LAMP2A expression and the accumulation of CMA substrate proteins in pancreatic and hepatic tissues. The activator AR7 successfully restored CMA function, enhanced anti-inflammatory and antioxidant responses, and mitigated pancreatic and liver damage in SAP rat. In contrast, the CMA inhibitor PPD exacerbated liver injury, underscoring CMA's protective role in SAP-ALI. Mechanistic analyses demonstrated that CMA reactivation activated the Keap1/Nrf2 signaling pathway, leading to increased expression of antioxidant-related genes and suppression of NLRP3 inflammasome activation. Specifically, the protective effects of AR7-induced CMA activation were significantly reversed by the Nrf2 inhibitor ML385, which inhibited Nrf2 signaling and its associated protein levels. These findings show AR7-induced CMA reactivation as a promising therapeutic strategy for SAP-ALI, primarily through its enhancement of Keap1/Nrf2-regulated antioxidant pathways and inhibition of NLRP3 inflammasome activation.

Regulation of pattern recognition receptor signaling by palmitoylation

Pattern recognition receptors (PRRs), consisting of Toll-like receptors, RIG-I-like receptors, cytosolic DNA sensors, and NOD-like receptors, sense exogenous pathogenic molecules and endogenous damage signals to maintain physiological homeostasis. Upon activation, PRRs stimulate the sensitization of nuclear factor κB, mitogen-activated protein kinase, TANK-binding kinase 1-interferon (IFN) regulatory factor, and inflammasome signaling pathways to produce inflammatory factors and IFNs to activate Janus kinase/signal transducer and activator of transcription signaling pathways, resulting in anti-infection, antitumor, and other specific immune responses. Palmitoylation is a crucial type of post-translational modification that reversibly alters the localization, stability, and biological activity of target molecules. Here, we discuss the available knowledge on the biological roles and underlying mechanisms linked to protein palmitoylation in modulating PRRs and their downstream signaling pathways under physiological and pathological conditions. Moreover, recent advances in the use of palmitoylation as an attractive therapeutic target for disorders caused by the dysregulation of PRRs were summarized.

PEX11B palmitoylation couples peroxisomal dysfunction with Schwann cells fail in diabetic neuropathy

BACKGROUND

Diabetic neuropathy (DN) is a prevalent and painful complication of diabetes; however, the mechanisms underlying its pathogenesis remain unclear, and effective clinical treatments are lacking. This study aims to explore the role of peroxisomes in Schwann cells in DN.

METHODS

The abundance of peroxisomes in the sciatic nerves of mice or Schwann cells was analyzed using laser confocal super-resolution imaging and western blotting. The RFP-GFP-SKL (Ser-Lys-Leu) probe was utilized to assess pexophagy (peroxisomes autophagy) levels. To evaluate the palmitoylation of PEX11B, the acyl-resin assisted capture (acyl-RAC) assay and the Acyl-Biotin Exchange (ABE) assay were employed. Additionally, MR (Mendelian randomization) analysis was conducted to investigate the potential causal relationship between DN and MS (Multiple sclerosis).

RESULTS

There was a decrease in peroxisomal abundance in the sciatic nerves of diabetic mice, and palmitic acid (PA) induced a reduction in peroxisomal abundance by inhibiting peroxisomal biogenesis in Schwann cells. Mechanistically, PA induced the palmitoylation of PEX11B at C25 site, disrupting its self-interaction and impeding peroxisome elongation. Fenofibrate, a PPARα agonist, effectively rescued peroxisomal dysfunction caused by PA and restored the peroxisomal abundance in diabetic mice. Lastly, MR analysis indicates a notable causal influence of DN on MS, with its onset and progression intricately linked to peroxisomal dysfunction.

CONCLUSIONS

Targeting the peroxisomal biogenesis pathway may be an effective strategy for preventing and treating DN, underscoring the importance of addressing MS risk at the onset of DN.

ZDHHC18 promotes renal fibrosis development by regulating HRAS palmitoylation

Fibrosis is the final common pathway leading to end-stage chronic kidney disease (CKD). However, the function of protein palmitoylation in renal fibrosis and the underlying mechanisms remain unclear. In this study, we observed that expression of the palmitoyltransferase ZDHHC18 was significantly elevated in unilateral ureteral obstruction (UUO) and folic acid-induced (FA-induced) renal fibrosis mouse models and was significantly upregulated in fibrotic kidneys of patients with CKD. Functionally, tubule-specific deletion of ZDHHC18 attenuated tubular epithelial cells' partial epithelial-mesenchymal transition (EMT) and then reduced the production of profibrotic cytokines and alleviated tubulointerstitial fibrosis. In contrast, ZDHHC18 overexpression exacerbated progressive renal fibrosis. Mechanistically, ZDHHC18 catalyzed the palmitoylation of HRAS, which was pivotal for its translocation to the plasma membrane and subsequent activation. HRAS palmitoylation promoted downstream phosphorylation of MEK/ERK and further activated Ras-responsive element-binding protein 1 (RREB1), enhancing SMAD binding to the Snai1 cis-regulatory regions. Taken together, our findings suggest that ZDHHC18 plays a crucial role in renal fibrogenesis and represents a potential therapeutic target for combating kidney fibrosis.

ABHD8 antagonizes inflammation by facilitating chaperone-mediated autophagy-mediated degradation of NLRP3

The NLRP3 inflammasome is a multiprotein complex that plays a vital role in the innate immune system in response to microbial infections and endogenous danger signals. Aberrant activation of the NLRP3 inflammasome is implicated in a spectrum of inflammatory and autoimmune diseases, emphasizing the necessity for precise regulation of the NLRP3 inflammasome to maintain immune homeostasis. The protein level of NLRP3 is a limiting step for inflammasome activation, which must be tightly controlled to avoid detrimental consequences. Here, we demonstrate that ABHD8, a member of the α/β-hydrolase domain-containing (ABHD) family, interacts with NLRP3 and promotes its degradation through the chaperone-mediated autophagy (CMA) pathway. ABHD8 acts as a scaffold to recruit palmitoyltransferase ZDHHC12 to NLRP3 for its palmitoylation as well as subsequent CMA-mediated degradation. Notably, ABHD8 deficiency results in the stabilization of NLRP3 protein and promotes NLRP3 inflammasome activation. We further confirm that ABHD8 overexpression ameliorates LPS- or alum-triggered NLRP3 inflammasome activation in vivo. Interestingly, the nucleocapsid (N) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) impairs the ABHD8-NLRP3 association, resulting in an elevation in NLRP3 protein level and excessive inflammasome activation. These findings demonstrate that ABHD8 May represent a potential therapeutic target in conditions associated with NLRP3 inflammasome dysregulation.Abbreviations: 3-MA: 3-methyladenine; ABHD: α/β-hydrolase domain-containing; BMDMs: Bone marrow-derived macrophages; CFZ: carfilzomib; CHX: cycloheximide; CMA: chaperone-mediated autophagy; CQ: chloroquine; DAMPs: danger/damage-associated molecular patterns; HSPA8/HSC70: heat shock protein family A (Hsp70) member 8; LAMP2A: lysosomal associated membrane protein 2A; NH4Cl: ammonium chloride; NLRP3: NLR family pyrin domain containing 3; PAMPs: pathogen-associated molecular patterns; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2.

Dietary Palmitic Acid Drives a Palmitoyltransferase ZDHHC15-YAP Feedback Loop Promoting Tumor Metastasis

Elevated uptake of saturated fatty acid palmitic acid (PA) is associated with tumor metastasis; however, the precise mechanisms remain partially understood, hindering the development of therapy for PA-driven tumor metastasis. The Hippo-Yes-associated protein (Hippo/YAP) pathway is implicated in cancer progression. Here it is shown that a high-palm oil diet potentiates tumor metastasis in murine xenografts in part through YAP. It is found that the palmitoyltransferase ZDHHC15 is a YAP-regulated gene that forms a feedback loop with YAP. Notably, PA drives the ZDHHC15-YAP feedback loop, thus enforces YAP signaling, and hence promotes tumor metastasis in murine xenografts. In addition, it is shown that ZDHHC15 associates with Kidney and brain protein (KIBRA, also known as WW- and C2 domain-containing protein 1, WWC1), an upstream component of Hippo signaling, and mediates its palmitoylation. KIBRA palmitoylation leads to its degradation and regulates its subcellular localization and activity toward the Hippo/YAP pathway. Moreover, PA enhances KIBRA palmitoylation and degradation. It is further shown that combinatorial targeting of YAP and fatty acid synthesis exhibits augmented effects against metastasis formation in mice fed with a Palm diet. Collectively, these findings uncover a ZDHHC15-YAP feedback loop as a previously unrecognized mechanism underlying PA-promoted tumor metastasis and support targeting YAP and fatty acid synthesis as potential therapeutic targets in PA-driven tumor metastasis.

VANGL2 alleviates inflammatory bowel disease by recruiting the ubiquitin ligase MARCH8 to limit NLRP3 inflammasome activation through OPTN-mediated selective autophagy

Inflammatory bowel disease (IBD) is a chronic and potentially life-threatening inflammatory disease of gastroenteric tissue characterized by episodes of intestinal inflammation, but the underlying mechanisms remain elusive. Here, we explore the role and precise mechanism of Van-Gogh-like 2 (VANGL2) during the pathogenesis of IBD. VANGL2 decreases in IBD patients and dextran sulfate sodium (DSS)-induced colitis in mice. Myeloid VANGL2 deficiency exacerbates the progression of DSS-induced colitis in mice and specifically enhances the activation of NLRP3 inflammasome in macrophages. NLRP3-specific inhibitor MCC950 effectively alleviates DSS-induced colitis in VANGL2 deficient mice. Mechanistically, VANGL2 interacts with NLRP3 and promotes the autophagic degradation of NLRP3 through enhancing the K27-linked polyubiquitination at lysine 823 of NLRP3 by recruiting E3 ligase MARCH8, leading to optineurin (OPTN)-mediated selective autophagy. Notably, decreased VANGL2 in the peripheral blood mononuclear cells from IBD patients results in overt NLRP3 inflammasome activation and sustained inflammation. Taken together, this study demonstrates that VANGL2 acts as a repressor of IBD progression by inhibiting NLRP3 inflammasome activation and provides insights into the crosstalk between inflammation and autophagy in preventing IBD.

Greasing the wheels of inflammasome formation: regulation of NLRP3 function by S-linked fatty acids

NLRP3 is an inflammasome seeding pattern recognition receptor that initiates a pro-inflammatory signalling cascade in response to changes in intracellular homeostasis that are indicative of bacterial infection or tissue damage. Several types of post-translational modification (PTM) have been identified that are added to NLRP3 to regulate its activity. Recent progress has revealed that NLRP3 is subject to a further type of PTM, S-acylation (or palmitoylation), which involves the reversible addition of long-chain fatty acids to target cysteine residues by opposing sets of enzymes. This review provides an overview of recent studies that have identified S-acylation as an important modifier of NLRP3 function. The essential role of S-acylation in the recruitment of NLRP3 to intracellular membranes and the consequences of S-acylation-dependent membrane recruitment on NLRP3 localisation and activation are discussed in detail.

Sulforaphane relieved inflammation symptoms in EAP mice by blocking oxidative stress and NLRP3 inflammasome activation through the Nrf2 pathway

Chronic prostatitis and chronic pelvic pain syndrome (CP/CPPS) are diagnosed in patients with various pelvic or genitourinary symptoms irrespective of the presence of a tender prostate. The etiology of chronic nonbacterial prostatitis remains unclear. Current treatments such as alpha-blockers, neuroleptics, anti-inflammatory, medications, and physical therapy, are often unsatisfactory. New treatments, as well as an improved knowledge of the underlying CP/CPPS pathogenesis, are thus needed. Sulforaphane (SFN), an isothiocyanate found in large quantities in Brassica species, has shown therapeutic effects on inflammation and cancer, and can protect against DNA damage and modulate the cell cycle to control apoptosis, angiogenesis, and metastasis. At the molecular level, SFN modulates cell homeostasis by activating the transcription factor Nrf2. However, its effect on CP/CPPS is not clear. Here, SFN was found to alleviate inflammation by suppressing NLRP3 inflammasomes via the Nrf2/HO-1 axis, as demonstrated in both animal and cellular analyses.

Lysosome-related proteins may have changes in the urinary exosomes of patients with acute gout attack

BACKGROUND

The autophagy-lysosome is intricately linked to the development of gout. At present, the diagnosis and monitoring of gout are mainly invasive tests, which cannot predict the occurrence of gout in the acute phase, and bring new pain to patients. This study focuses on the changes of lysosome-related proteins in urinary exosomes of patients with acute gout attack to explore the potential noninvasive biomarkers clinical application value.

METHODS

Urine samples were collected from the subject and exosomes were extracted. To explore the differentially expressed proteins in urinary exosomes among acute gout patients (AD group), intermittent gout patients (ID group) and normal controls (NC group) by DIA mass spectrometry. Urinary exosomal lysosome associated proteins were analyzed and receiver operating characteristic (ROC) curves of differentially expressed proteins were drawn to evaluate their clinical value in monitoring acute gout attack.

RESULTS

A total of 1896 proteins were detected between AD group and ID group, of which 121 proteins were differentially expressed (FC > 1.5 and p < 0.05). There were three lysosomal-related proteins differentially expressed in urinary exosomes between AD group and ID group. Compared with the ID group, the expression of Cathepsin Z (CTSZ) and AP-1 complex subunit beta-1 (AP1B1) was increased, while the expression of Lysosome-associated membrane glycoprotein 2 (LAMP2) was decreased in AD group. The ROC analysis showed that CTSZ, AP1B1 and LAMP2 had a strong ability to predict acute gout attack, with AUC of 0.826, 0.847 and 0.882, respectively.

CONCLUSIONS

There are many specific protein changes in the urinary exosomes of patients with acute gout attack. The urinary exosomes of patients with acute gout attack may exhibit alterations in lysosome-related proteins, particularly CTSZ, AP1B1, and LAMP2, which may become potential biomarkers for monitoring acute gout attack.

Ferroptosis and pyroptosis are connected through autophagy: a new perspective of overcoming drug resistance

Drug resistance is a common challenge in clinical tumor treatment. A reduction in drug sensitivity of tumor cells is often accompanied by an increase in autophagy levels, leading to autophagy-related resistance. The effectiveness of combining chemotherapy drugs with autophagy inducers/inhibitors has been widely confirmed, but the mechanisms are still unclear. Ferroptosis and pyroptosis can be affected by various types of autophagy. Therefore, ferroptosis and pyroptosis have crosstalk via autophagy, potentially leading to a switch in cell death types under certain conditions. As two forms of inflammatory programmed cell death, ferroptosis and pyroptosis have different effects on inflammation, and the cGAS-STING signaling pathway is also involved. Therefore, it also plays an important role in the progression of some chronic inflammatory diseases. This review discusses the relationship between autophagy, ferroptosis and pyroptosis, and attempts to uncover the reasons behind the evasion of tumor cell death and the nature of drug resistance.

Revealing the dance of NLRP3: spatiotemporal patterns in inflammasome activation

The nucleotide-binding domain, leucine-rich repeat, and pyrin domain containing-protein 3 (NLRP3) inflammasome is a multiprotein complex that plays a critical role in the innate immune response to both infections and sterile stressors. Dysregulated NLRP3 activation has been implicated in a variety of autoimmune and inflammatory diseases, including cryopyrin-associated periodic fever syndromes, diabetes, atherosclerosis, Alzheimer's disease, inflammatory bowel disease, and cancer. Consequently, fine-tuning NLRP3 activity holds significant therapeutic potential. Studies have implicated several organelles, including mitochondria, lysosomes, the endoplasmic reticulum (ER), the Golgi apparatus, endosomes, and the centrosome, in NLRP3 localization and inflammasome assembly. However, reports of conflict and many factors regulating interactions between NLRP3 and subcellular organelles remain unknown. This review synthesizes the current understanding of NLRP3 spatiotemporal dynamics, focusing on recent literature that elucidates the roles of subcellular localization and organelle stress in NLRP3 signaling and its crosstalk with other innate immune pathways converging at these organelles.

Recent Overview of Protein Palmitoylation and Profiling Methodologies

Protein palmitoylation is a reversible posttranslational modification in which a palmitoyl group (a 16-carbon saturated fatty acid) is covalently attached to cysteine residues on proteins, typically through a thioester bond. This modification affects the protein's hydrophobicity, influencing its membrane association, localization, stability, trafficking, and overall function. Dysregulation of palmitoylation has been implicated in diseases such as cancer, neurodegenerative diseases, and cardiovascular disorders. In this review, we summarize the recent findings related to protein palmitoylation and its biological functions. More importantly, we examine proteomic studies that utilize active-based protein profiling (ABPP) to design novel probes or inhibitors aimed at enhancing the accuracy and efficiency of large-scale analyses of protein palmitoylation. These advancements will facilitate the findings of novel therapeutic targets and the designing of targeted therapies, providing increasingly critical insights into the role of this modification in health and diseases.

Selective protein degradation through chaperone‑mediated autophagy: Implications for cellular homeostasis and disease (Review)

Cells rely on autophagy for the degradation and recycling of damaged proteins and organelles. Chaperone-mediated autophagy (CMA) is a selective process targeting proteins for degradation through the coordinated function of molecular chaperones and the lysosome‑associated membrane protein‑2A receptor (LAMP2A), pivotal in various cellular processes from signal transduction to the modulation of cellular responses under stress. In the present review, the intricate regulatory mechanisms of CMA were elucidated through multiple signaling pathways such as retinoic acid receptor (RAR)α, AMP‑activated protein kinase (AMPK), p38‑TEEB‑NLRP3, calcium signaling‑NFAT and PI3K/AKT, thereby expanding the current understanding of CMA regulation. A comprehensive exploration of CMA's versatile roles in cellular physiology were further provided, including its involvement in maintaining protein homeostasis, regulating ferroptosis, modulating metabolic diversity and influencing cell cycle and proliferation. Additionally, the impact of CMA on disease progression and therapeutic outcomes were highlighted, encompassing neurodegenerative disorders, cancer and various organ‑specific diseases. Therapeutic strategies targeting CMA, such as drug development and gene therapy were also proposed, providing valuable directions for future clinical research. By integrating recent research findings, the present review aimed to enhance the current understanding of cellular homeostasis processes and emphasize the potential of targeting CMA in therapeutic strategies for diseases marked by CMA dysfunction.

From fat to fire: The lipid-inflammasome connection

Inflammasomes are multiprotein complexes that play a crucial role in regulating immune responses by governing the activation of Caspase-1, the secretion of pro-inflammatory cytokines, and the induction of inflammatory cell death, pyroptosis. The inflammasomes are pivotal in effective host defense against a range of pathogens. Yet, overt activation of inflammasome signaling can be detrimental. The most well-studied NLRP3 inflammasome has the ability to detect a variety of stimuli including pathogen-associated molecular patterns, environmental irritants, and endogenous stimuli released from dying cells. Additionally, NLRP3 acts as a key sensor of cellular homeostasis and can be activated by disturbances in diverse metabolic pathways. Consequently, NLRP3 is considered a key player linking metabolic dysregulation to numerous inflammatory disorders such as gout, diabetes, and atherosclerosis. Recently, compelling studies have highlighted a connection between lipids and the regulation of NLRP3 inflammasome. Lipids are integral to cellular processes that serve not only in maintaining the structural integrity and subcellular compartmentalization, but also in contributing to physiological equilibrium. Certain lipid species are known to define NLRP3 subcellular localization, therefore directly influencing the site of inflammasome assembly and activation. For instance, phosphatidylinositol 4-phosphate plays a crucial role in NLRP3 localization to the trans Golgi network. Moreover, new evidence has demonstrated the roles of lipid biosynthesis and trafficking in activation of the NLRP3 inflammasome. This review summarizes and discusses these emerging and varied roles of lipid metabolism in inflammasome activation. A deeper understanding of lipid-inflammasome interactions may open new avenues for therapeutic interventions to prevent or treat chronic inflammatory and autoimmune conditions.

Tracking Chaperone-Mediated Autophagy Flux with a pH-Resistant Fluorescent Reporter

Chaperone-mediated autophagy (CMA) is a selective autophagic pathway responsible for degrading cytoplasmic proteins within lysosomes. Monitoring CMA flux is essential for understanding its functions and molecular mechanisms but remains technically complex and challenging. In this study, we developed a pH-resistant probe, KFERQ-Gamillus, by screening various green fluorescent proteins. This probe is activated under conditions known to induce CMA, such as serum starvation, and relies on LAMP2A and the KFERQ motif for lysosomal localization and degradation, demonstrating its specificity for the CMA pathway. It enables the detection of CMA activity in living cells through both microscopy and image-based flow cytometry. Additionally, we created a dual-reporter system, KFERQ-Gamillus-Halo, by integrating KFERQ-Gamillus with the Halo-tag system. This probe not only distinguishes between protein synthesis and degradation but also facilitates the detection of intracellular CMA flux via immunoblotting and the rapid assessment of CMA activity using flow cytometry. Together, the KFERQ-Gamillus-Halo probe provides quantitative and time-resolved monitoring for CMA activity and flux in living cells. This tool holds promising potential for high-throughput screening and biomedical research related to CMA.

Anti-inflammatory Effects of Membrane Vesicles from Eubacterium rectale via the NLRP3 Signal Pathway

Eubacterium rectale (E. rectale) has the ability to attenuate systemic and intestinal inflammation. Its naturally secreted membrane vesicles (MVs) likely play a crucial role in this process. The objective of this study is to investigate the anti-inflammatory effects of E. rectale and its membrane vesicles (MVs). An inflammation model was established by inducing an inflammatory response in Raw 264.7 cells using lipopolysaccharide (LPS). Subsequently, the cells were pre-treated with E. rectale and its MVs, and the expression levels of IL-1β, IL-6, TNF-α, and IL-10 in the cells were then detected using RT-qPCR. ELISA was used to measure the secretion levels of IL-1β, while western blot analysis was employed to assess the expression of key proteins in the IL-1β pathway, specifically ASC, Caspase 1, and NLRP3. The results revealed that both E. rectale and its MVs significantly reduced the expression of the inflammatory cytokines IL-1β and TNF-α in Raw 264.7 cells, which were induced by LPS. Additionally, they markedly upregulated the expression of the anti-inflammatory cytokine IL-10 and suppressed IL-1β expression via the NLRP3-Caspase 1-ASC signaling pathway. These findings suggest that E. rectale, through its membrane vesicles, can attenuate LPS-induced NLRP3 inflammasome activation, thereby mitigating the inflammatory response in Raw 264.7 cells.

S-palmitoylation of MAP kinase is essential for fungal virulence

S-palmitoylation is an important reversible protein post-translational modification in organisms. However, its role in fungi is uncertain. Here, we found the treatment of the rice false fungus Ustilaginoidea virens with S-palmitoylation inhibitor 2 BP resulted in a significant decrease in fungal virulence. Comprehensive identification of S-palmitoylation sites and proteins in U. virens revealed a total of 4,089 S-palmitoylation sites identified among 2,192 proteins and that S-palmitoylated proteins were involved in diverse biological processes. Among the five palmitoyltransferases, UvPfa3 and UvPfa4 were found to regulate the pathogenicity of U. virens. We then performed quantitative proteomic analysis of ∆UvPfa3 and ∆UvPfa4 mutants. Interestingly, S-palmitoylated proteins were significantly enriched in the mitogen-activated protein kinase and autophagy pathways, and MAP kinase UvSlt2 was confirmed to be an S-palmitoylated protein which was palmitoylated by UvPfa4. Mutations of S-palmitoylation sites in UvSlt2 resulted in significantly reduced fungal virulence and decreased kinase enzymatic activity and phosphorylation levels. Simulations of molecular dynamics demonstrated mutation of S-palmitoylation sites in UvSlt2 causing decreased hydrophobic solvent-accessible surface area, thereby weakening the bonding force with its substrate UvRlm1. Taken together, S-palmitoylation promotes U. virens virulence through palmitoylation of MAP kinase UvSlt2 by palmitoyltransferase UvPfa4. This enhances the enzymatic phosphorylation activity of the kinase, thereby increasing hydrophobic solvent-accessible surface area and binding activity between the UvSlt2 enzyme and its substrate UvRlm1. Our studies provide a framework for dissecting the biological functions of S-palmitoylation and reveal an important role for S-palmitoylation in regulating the virulence of the pathogen.IMPORTANCES-palmitoylation is an important post-translational lipid modification of proteins. However, its role in fungi is uncertain. In this study, we found that S-palmitoylation promotes virulence of rice false smut fungus U. virens through palmitoylation of MAP kinase UvSlt2 by palmitoyltransferase UvPfa4. This enhances the enzymatic phosphorylation activity of the kinase, thereby increasing hydrophobic solvent-accessible surface area and binding activity between the UvSlt2 enzyme and its substrate UvRlm1. Our studies provide a framework for dissecting the biological functions of S-palmitoylation and reveal an important role for S-palmitoylation in regulating the virulence of the pathogen. This is the first functional study to reveal the role of S-palmitoylation in fungal virulence.

Improved Antitumor Efficiency of N4 -Tetradecyloxycarbonyl Gemcitabine-Loaded Liposomes for Pancreatic Cancer Chemotherapy

Background

Gemcitabine (Gem) is one of the first-line chemotherapy drugs for pancreatic cancer treatment. However, its short half-life in plasma and adverse effects limited its broader application.

Methods

A novel Gem derivative (N4 -tetradecyloxycarbonyl gemcitabine, tcGem) was synthesized and encapsulated into liposomes (LipotcGem) to overcome the above shortcomings.

Results

LipotcGem has been successfully formulated, with the average size of 115 nm, zeta potential values of -36 mV, encapsulation efficiency of up to 98%, and drug loading capacity of 8.1%. Compared to Gem, LipotcGem improved in vitro antitumor activity significantly, as evidenced by the lower IC50, the higher percentage of apoptotic cells, the stronger ability to inhibit cell migration and invasion due to the higher cellular accumulation (100 times). Additionally, the endocytosis of LipotcGem was mainly mediated by caveolae, and was then processed in the lysosome, where tcGem was released and hydrolyzed into Gem. LipotcGem inhibited tumor growth by 70% in subcutaneous xenograft model and 90% in orthotopic xenograft model, respectively. LipotcGem suppressed tumor metastasis and prolonged survival without perceptible systemic toxicity, which may be caused by the longer t1/2 in vivo (3.5 times, 5.23 vs 1.46 h) and more enrichment in tumor tissue (750 times).

Conclusion

LipotcGem significantly increased the anti-tumor efficiency and decreased the toxicity for chemotherapy of pancreatic cancer.

Chaperone-mediated autophagy as a modulator of aging and longevity

Chaperone-mediated autophagy (CMA) is the lysosomal degradation of individually selected proteins, independent of vesicle fusion. CMA is a central part of the proteostasis network in vertebrate cells. However, CMA is also a negative regulator of anabolism, and it degrades enzymes required for glycolysis, de novo lipogenesis, and translation at the cytoplasmic ribosome. Recently, CMA has gained attention as a possible modulator of rodent aging. Two mechanistic models have been proposed to explain the relationship between CMA and aging in mice. Both of these models are backed by experimental data, and they are not mutually exclusionary. Model 1, the "Longevity Model," states that lifespan-extending interventions that decrease signaling through the INS/IGF1 signaling axis also increase CMA, which degrades (and thereby reduces the abundance of) several proteins that negatively regulate vertebrate lifespan, such as MYC, NLRP3, ACLY, and ACSS2. Therefore, enhanced CMA, in early and midlife, is hypothesized to slow the aging process. Model 2, the "Aging Model," states that changes in lysosomal membrane dynamics with age lead to age-related losses in the essential CMA component LAMP2A, which in turn reduces CMA, contributes to age-related proteostasis collapse, and leads to overaccumulation of proteins that contribute to age-related diseases, such as Alzheimer's disease, Parkinson's disease, cancer, atherosclerosis, and sterile inflammation. The objective of this review paper is to comprehensively describe the data in support of both of these explanatory models, and to discuss the strengths and limitations of each.

ZDHHC7-mediated S-palmitoylation of ATG16L1 facilitates LC3 lipidation and autophagosome formation

Macroautophagy/autophagy is a fundamental cellular catabolic process that delivers cytoplasmic components into double-membrane vesicles called autophagosomes, which then fuse with lysosomes and their contents are degraded. Autophagy recycles cytoplasmic components, including misfolded proteins, dysfunctional organelles and even microbial invaders, thereby playing an essential role in development, immunity and cell death. Autophagosome formation is the main step in autophagy, which is governed by a set of ATG (autophagy related) proteins. ATG16L1 interacts with ATG12-ATG5 conjugate to form an ATG12-ATG5-ATG16L1 complex. The complex acts as a ubiquitin-like E3 ligase that catalyzes the lipidation of MAP1LC3/LC3 (microtubule associated protein 1 light chain 3), which is crucial for autophagosome formation. In the present study, we found that ATG16L1 was subject to S-palmitoylation on cysteine 153, which was catalyzed by ZDHHC7 (zinc finger DHHC-type palmitoyltransferase 7). We observed that re-expressing ATG16L1 but not the S-palmitoylation-deficient mutant ATG16L1C153S rescued a defect in the lipidation of LC3 and the formation of autophagosomes in ATG16L1-KO (knockout) HeLa cells. Furthermore, increasing ATG16L1 S-palmitoylation by ZDHHC7 expression promoted the production of LC3-II, whereas reducing ATG16L1 S-palmitoylation by ZDHHC7 deletion inhibited the LC3 lipidation process and autophagosome formation. Mechanistically, the addition of a hydrophobic 16-carbon palmitoyl group on Cys153 residue of ATG16L1 enhances the formation of ATG16L1-WIPI2B complex and ATG16L1-RAB33B complex on phagophore, thereby facilitating the LC3 lipidation process and autophagosome formation. In conclusion, S-palmitoylation of ATG16L1 is essential for the lipidation process of LC3 and the formation of autophagosomes. Our research uncovers a new regulatory mechanism of ATG16L1 function in autophagy.Abbreviation: ABE: acyl-biotin exchange; ATG: autophagy related; Baf-A1: bafilomycin A1; 2-BP: 2-bromopalmitate; CCD: coiled-coil domain; co-IP: co-immunoprecipitation; CQ: chloroquine; EBSS: Earle's balanced salt solution; HAM: hydroxylamine; KO: knockout; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NP-40: Nonidet P-40; PBS: phosphate-buffered saline; PE: phosphatidylethanolamine; PtdIns3K-C1: class III phosphatidylinositol 3-kinase complex I; PTM: post-translational modification; RAB33B: RAB33B, member RAS oncogene family; RB1CC1/FIP200: RB1 inducible coiled-coil 1; SDS: sodium dodecyl sulfate; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscope; WD: tryptophan and aspartic acid; WIPI2B: WD repeat domain, phosphoinositide interacting 2B; WT: wild-type; ZDHHC: zinc finger DHHC-type palmitoyltransferase.

Chaperone-Mediated Autophagy in Brain Injury: A Double-Edged Sword with Therapeutic Potentials

Autophagy is an intracellular recycling process that maintains cellular homeostasis by degrading excess or defective macromolecules and organelles. Chaperone-mediated autophagy (CMA) is a highly selective form of autophagy in which a substrate containing a KFERQ-like motif is recognized by a chaperone protein, delivered to the lysosomal membrane, and then translocated to the lysosome for degradation with the assistance of lysosomal membrane protein 2A. Normal CMA activity is involved in the regulation of cellular proteostasis, metabolism, differentiation, and survival. CMA dysfunction disturbs cellular homeostasis and directly participates in the pathogenesis of human diseases. Previous investigations on CMA in the central nervous system have primarily focus on neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. Recently, mounting evidence suggested that brain injuries involve a wider range of types and severities, making the involvement of CMA in the bidirectional processes of damage and repair even more crucial. In this review, we summarize the basic processes of CMA and its associated regulatory mechanisms and highlight the critical role of CMA in brain injury such as cerebral ischemia, traumatic brain injury, and other specific brain injuries. We also discuss the potential of CMA as a therapeutic target to treat brain injury and provide valuable insights into clinical strategies.

Mechanisms and cross-talk of regulated cell death and their epigenetic modifications in tumor progression

Cell death is a fundamental part of life for metazoans. To maintain the balance between cell proliferation and metabolism of human bodies, a certain number of cells need to be removed regularly. Hence, the mechanisms of cell death have been preserved during the evolution of multicellular organisms. Tumorigenesis is closely related with exceptional inhibition of cell death. Mutations or defects in cell death-related genes block the elimination of abnormal cells and enhance the resistance of malignant cells to chemotherapy. Therefore, the investigation of cell death mechanisms enables the development of drugs that directly induce tumor cell death. In the guidelines updated by the Cell Death Nomenclature Committee (NCCD) in 2018, cell death was classified into 12 types according to morphological, biochemical and functional classification, including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, PARP-1 parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence and mitotic catastrophe. The mechanistic relationships between epigenetic controls and cell death in cancer progression were previously unclear. In this review, we will summarize the mechanisms of cell death pathways and corresponding epigenetic regulations. Also, we will explore the extensive interactions between these pathways and discuss the mechanisms of cell death in epigenetics which bring benefits to tumor therapy.

Mechanistic exploration of ubiquitination-mediated pathways in cerebral ischemic injury

The ubiquitin-proteasome system (UPS) plays a pivotal role in regulating protein homeostasis and cellular processes, including protein degradation, trafficking, DNA repair, and cell signaling. During cerebral ischemia, ischemic conditions profoundly disrupt UPS activity, leading to proteasomal dysfunction and the accumulation of abnormal proteins. This imbalance contributes to neuronal injury and cell death observed in ischemic stroke. The UPS is intricately linked to various signaling pathways crucial for neuronal survival, inflammation, and cellular stress response, such as NF-κB, TRIM, TRIP, JAK-STAT, PI3K/Akt, and ERK1/2. Alterations in the ubiquitination process can significantly impact the activation and regulation of these pathways, exacerbating ischemic brain injury. Therapeutic approaches targeting the UPS in cerebral ischemia aim to rebalance protein levels, reduce proteotoxic stress, and mitigate neuronal injury. Strategies include proteasome inhibition, targeting specific ubiquitin ligases and deubiquitinating enzymes, and modulating ubiquitination-mediated regulation of key signaling pathways implicated in ischemia-induced pathophysiology. Therefore, the present review discusses the molecular mechanisms underlying UPS dysfunction in ischemic stroke is crucial for developing effective therapeutic interventions. Modulating ubiquitination-mediated pathways through therapeutic interventions targeting specific UPS components holds significant promise for mitigating ischemic brain injury and promoting neuroprotection and functional recovery in patients with cerebral ischemia.

Progress in the mechanism of functional dyspepsia: roles of mitochondrial autophagy in duodenal abnormalities

Mitochondria are the main source of energy for cellular activity. Their functional damage or deficiency leads to cellular deterioration, which in turn triggers autophagic reactions. Taking mitochondrial autophagy as a starting point, the present review explored the mechanisms of duodenal abnormalities in detail, including mucosal barrier damage, release of inflammatory factors, and disruption of intracellular signal transduction. We summarized the key roles of mitochondrial autophagy in the abnormal development of the duodenum and examined the in-depth physiological and pathological mechanisms involved, providing a comprehensive theoretical basis for understanding the pathogenesis of functional dyspepsia. At present, it has been confirmed that an increase in the eosinophil count and mast cell degranulation in the duodenum can trigger visceral hypersensitive reactions and cause gastrointestinal motility disorders. In the future, it is necessary to continue exploring the molecular mechanisms and signaling pathways of mitochondrial autophagy in duodenal abnormalities. A deeper understanding of mitochondrial autophagy provides important references for developing treatment strategies for functional dyspepsia, thereby improving clinical efficacy and patient quality of life.