The emerging mechanisms and functions of microautophagy

Mitophagy in acute central nervous system injuries: regulatory mechanisms and therapeutic potentials

Acute central nervous system injuries, including ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, traumatic brain injury, and spinal cord injury, are a major global health challenge. Identifying optimal therapies and improving the long-term neurological functions of patients with acute central nervous system injuries are urgent priorities. Mitochondria are susceptible to damage after acute central nervous system injury, and this leads to the release of toxic levels of reactive oxygen species, which induce cell death. Mitophagy, a selective form of autophagy, is crucial in eliminating redundant or damaged mitochondria during these events. Recent evidence has highlighted the significant role of mitophagy in acute central nervous system injuries. In this review, we provide a comprehensive overview of the process, classification, and related mechanisms of mitophagy. We also highlight the recent developments in research into the role of mitophagy in various acute central nervous system injuries and drug therapies that regulate mitophagy. In the final section of this review, we emphasize the potential for treating these disorders by focusing on mitophagy and suggest future research paths in this area.

Autophagy-targeting modulation to promote peripheral nerve regeneration

Nerve regeneration following traumatic peripheral nerve injuries and neuropathies is a complex process modulated by diverse factors and intricate molecular mechanisms. Past studies have focused on factors that stimulate axonal outgrowth and myelin regeneration. However, recent studies have highlighted the pivotal role of autophagy in peripheral nerve regeneration, particularly in the context of traumatic injuries. Consequently, autophagy-targeting modulation has emerged as a promising therapeutic approach to enhancing peripheral nerve regeneration. Our current understanding suggests that activating autophagy facilitates the rapid clearance of damaged axons and myelin sheaths, thereby enhancing neuronal survival and mitigating injury-induced oxidative stress and inflammation. These actions collectively contribute to creating a favorable microenvironment for structural and functional nerve regeneration. A range of autophagy-inducing drugs and interventions have demonstrated beneficial effects in alleviating peripheral neuropathy and promoting nerve regeneration in preclinical models of traumatic peripheral nerve injuries. This review delves into the regulation of autophagy in cell types involved in peripheral nerve regeneration, summarizing the potential drugs and interventions that can be harnessed to promote this process. We hope that our review will offer novel insights and perspectives on the exploitation of autophagy pathways in the treatment of peripheral nerve injuries and neuropathies.

Comparative Analysis of Human Brain RNA-seq Reveals the Combined Effects of Ferroptosis and Autophagy on Alzheimer's Disease in Multiple Brain Regions

Ferroptosis and autophagy are closely associated with Alzheimer's disease (AD). Elevated ferric ion levels can induce oxidative stress and chronic inflammatory responses, resulting in brain tissue damage and further neurological cell damage. Autophagy in Alzheimer's has a dual role. On one hand, it protects neurons by removing β-amyloid and cellular damage products caused by oxidative stress and inflammation. On the other hand, abnormal autophagy is linked to neuronal apoptosis and neurodegeneration. However, the intricate interplay between ferroptosis and autophagy in AD remains insufficiently explored. This study focuses on the roles of ferroptosis and autophagy in AD and their interconnection through bioinformatics analysis, shedding light on the disease. Ferroptosis and autophagy significantly correlate with the development and course of AD. Using PPI network analysis and unsupervised consistency clustering analysis, we uncovered a complex network of interactions between ferroptosis and autophagy during disease progression, demonstrating a significant congruence in their modification patterns. Functional analyses further demonstrated that ferroptosis and autophagy together affect the immunological status and synaptic regulation in hippocampal regions in patients with AD, which significantly impacts the start and progression of the disease.

Baicalein tethers CD274/PD-L1 for autophagic degradation to boost antitumor immunity

Immune checkpoint inhibitors, especially those targeting CD274/PD-L1yield powerful clinical therapeutic efficacy. Thoughmuch progress has been made in the development of antibody-basedCD274 drugs, chemical compounds applied for CD274degradation remain largely unavailable. Herein,baicalein, a monomer of traditional Chinese medicine, isscreened and validated to target CD274 and induces itsmacroautophagic/autophagic degradation. Moreover, we demonstrate thatCD274 directly interacts with MAP1LC3B (microtubule associatedprotein 1 light chain 3 beta). Intriguingly, baicalein potentiatesCD274-LC3 interaction to facilitate autophagic-lysosomal degradationof CD274. Importantly, targeted CD274. degradation via baicaleininhibits tumor development by boosting T-cell-mediated antitumorimmunity. Thus, we elucidate a critical role of autophagy-lysosomalpathway in mediating CD274 degradation, and conceptually demonstratethat the design of a molecular "glue" that tethers the CD274-LC3interaction is an appealing strategy to develop CD274 inhibitors incancer therapy.Abbreviations: ATTECs: autophagy-tethering compounds; AUTACs: AUtophagy-TArgeting Chimeras; AUTOTACs: AUTOphagy-TArgeting Chimeras; AMPK: adenosine 5'-monophosphate (AMP)-activated protein kinase; BiFC: bimolecular fluorescence complementation; BafA1: bafilomycin A1; CD274/PD-L1/B7-H1: CD274 molecule; CQ: chloroquine; CGAS: cyclic GMP-AMP synthase; DAPI: 4'6-diamino-2-phenylindole; FITC: fluorescein isothiocyanate isomer; GFP: green fluorescent protein; GZMB: granzyme B; IHC: immunohistochemistry; ICB: immune checkpoint blockade; KO: knockout; KD: equilibrium dissociation constant; LYTAC: LYsosome-TArgeting Chimera; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MST: microscale thermophoresis; NFAT: nuclear factor of activated T cells; NFKB/NF-kB: nuclear factor kappa B; NSCLC: non-small-cell lung cancer; PDCD1: programmed cell death 1; PROTACs: PROteolysis TArgeting Chimeras; PRF1: perforin 1; PE: phosphatidylethanolamine; PHA: phytohemagglutinin; PMA: phorbol 12-myristate 13-acetate; STAT: signal transducer and activator of transcription; SPR: surface plasmon resonance; TILs: tumor-infiltrating lymphocyte; TME: tumor microenvironment.

LncRNA HITT inhibits autophagy by attenuating ATG12-ATG5-ATG16L1 complex formation

Dysregulated autophagy has been implicated in the pathogenesis of numerous diseases, including cancer. Despite extensive research on the underlying mechanisms of autophagy, the involvement of long non-coding RNAs (lncRNAs) remains poorly understood. Here, we demonstrate that a previously identified lncRNA, HITT (HIF-1α inhibitor at the translation level), is closely associated with biological processes such as autophagy through unbiased bioinformatic analysis. Subsequent studies demonstrate that HITT is increased by several autophagic stimuli, including PI-103, a potent inhibitor of PI3K and mTOR. This is caused by a reduction in the binding between HITT and AGO2, resulting in a reduction in the activity of miR-205 towards HITT degradation. Increased HITT then binds to a key autophagy protein, Autophagy-related 5 (ATG5), and inhibits autophagosome formation by preventing the formation of the ATG12-ATG5-ATG16L1 complex. This results in HITT sensitizing PI-103-mediated cell death both in vitro and in vivo in nude mice by attenuating protective autophagy. The data presented herein demonstrate that HITT is a newly identified RNA regulator of autophagy and that it can be used to sensitize the colon cancer response to cell death by blocking the protective autophagy.

Multi-omics analysis of two rat models reveals potential role of vesicle transport and autophagy in right ventricular remodeling

Right ventricular failure as a severe consequence of pulmonary arterial hypertension (PAH) is an independent risk factor for poor prognosis, although the pathogenesis of right ventricular remodeling (RVR) remains unclear. Exploring the shared molecular pathways and key molecules in the right ventricle in monocrotaline (MCT) and pulmonary artery banding (PAB) rat models may reveal critical RVR mechanisms. Untargeted proteome and metabolome analysis were performed on the right ventricular myocardium of two RVR models (MCT-induced PAH rats and PAB-operated rats) to identify the altered proteins and metabolites, followed by validation using parallel reaction monitoring analysis and quantitative real-time polymerase chain reaction (qPCR). The multi-omics profiles of MCT and PAB rat models were compared to explore the key dysregulated molecules and pathways in RVR. Our proteomics study identified 25 shared RVR-altered differentially expressed proteins. Multiple common biological pathways were identified between PAB and MCT rat models, encompassing myocardial remodeling and energy metabolism alternation, etc. Various molecules and pathways related to vesicle transport and autophagy were identified, including nidogen-1, the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) signaling pathway, and the microautophagy pathway (all previously unreported in RVR). Glycerophospholipid metabolism was the sole statistically significant common metabolic pathway enriched by metabolomics. Underreported biological processes, including vesicle transport and autophagy, may contribute to the pathophysiology of PAH-induced RVR.

Autophagy dysfunction links palmitic acid with macrophage inflammatory responses in large yellow croaker (Larimichthys crocea)

Autophagy is a cellular degradation process reliant on lysosome, crucial for preserving intracellular homeostasis. The key saturated fatty acid palmitic acid (PA) has been demonstrated to exert regulatory effects on autophagic activity in mammals. However, the precise impact of PA on autophagy and its role in fish remains incompletely understood. Thus, this study aimed to investigate the regulation of PA on autophagy and explore the role of autophagy in inflammatory responses triggered by PA in the head kidney macrophages of large yellow croaker. This study indicates that PA exposure can inhibit macrophage autophagy by reducing the expression of genes related to autophagy (e.g., beclin1, ulk1, and lc3), activating the negative regulator mTORC1 signaling pathway (p70S6K and S6), and hindering autophagic flux. This effect was observed to be amplified with increasing exposure time and concentration of PA. Similarly to the in vitro results, the palm oil (PO) diet significantly reduced autophagic activity in the head kidney of the croaker in vivo. Subsequent studies demonstrated that restoring autophagy led to a notable reduction in the expression of PA and PO-induced pro-inflammatory genes (il-1β, il-6, tnf-α, and cox-2), the activation of the MAPK signaling pathway (p38 and JNK), and the NLRP3 inflammasome levels, both in vitro and in vivo. In contrast, further inhibition of autophagy produced the opposite effect in vitro. In conclusion, this study demonstrates that PA exerts a dynamic inhibitory effect on autophagy in the head kidney macrophage, which in turn promotes PA-induced inflammatory responses. These findings provide valuable insights into how PA influences autophagy and inflammatory responses in fish immune cells, contributing to the theoretical framework for improving the use of vegetable oils in aquaculture.

β-hydroxybutyrate facilitates mitochondrial-derived vesicle biogenesis and improves mitochondrial functions

Mitochondrial dynamics and metabolites reciprocally influence each other. Mitochondrial-derived vesicles (MDVs) transport damaged mitochondrial components to lysosomes or the extracellular space. While many metabolites are known to modulate mitochondrial dynamics, it is largely unclear whether they are involved in MDV generation. Here, we discovered that the major component of ketone body, β-hydroxybutyrate (BHB), improved mitochondrial functions by facilitating the biogenesis of MDVs. Mechanistically, BHB drove specific lysine β-hydroxybutyrylation (Kbhb) of sorting nexin-9 (SNX9), a key regulator of MDV biogenesis. Kbhb increased SNX9 interaction with inner mitochondrial membrane (IMM)/matrix proteins and promoted the formation of IMM/matrix MDVs. SNX9 Kbhb was not only critical for maintaining mitochondrial homeostasis in cells but also protected mice from alcohol-induced liver injury. Altogether, our research uncovers the fact that metabolites influence the formation of MDVs by directly engaging in post-translational modifications of key protein machineries and establishes a framework for understanding how metabolites regulate mitochondrial functions.

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.

Covalent inhibitors possessing autophagy-modulating capabilities: charting novel avenues in drug design and discovery

Autophagy is a crucial cellular process in degrading damaged organelles and maintaining cellular homeostasis. By forming irreversible bonds with specific proteins, covalent inhibitors present a distinct advantage in regulating autophagy and its related pathways. These inhibitors can provide sustained modulation of autophagy at lower doses, improving therapeutic efficacy while minimizing adverse effects. We discuss their mechanisms, including how they affect autophagy-related enzymes and pathways, and their potential applications in the treatment of cancers and other autophagy-related disorders. Studying autophagy-related pathway targets will provide new insights for the development of covalent inhibitors and enhance therapeutic strategies for complex conditions.

The inducible role of autophagy in cell death: emerging evidence and future perspectives

BACKGROUND

Autophagy is a lysosome-dependent degradation pathway for recycling intracellular materials and removing damaged organelles, and it is usually considered a prosurvival process in response to stress stimuli. However, increasing evidence suggests that autophagy can also drive cell death in a context-dependent manner. The bulk degradation of cell contents and the accumulation of autophagosomes are recognized as the mechanisms of cell death induced by autophagy alone. However, autophagy can also drive other forms of regulated cell death (RCD) whose mechanisms are not related to excessive autophagic vacuolization. Notably, few reviews address studies on the transformation from autophagy to RCD, and the underlying molecular mechanisms are still vague.

AIM OF REVIEW

This review aims to summarize the existing studies on autophagy-mediated RCD, to elucidate the mechanism by which autophagy initiates RCD, and to comprehensively understand the role of autophagy in determining cell fate.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review highlights the prodeath effect of autophagy, which is distinct from the generally perceived cytoprotective role, and its mechanisms are mainly associated with the selective degradation of proteins or organelles essential for cell survival and the direct involvement of the autophagy machinery in cell death. Additionally, this review highlights the need for better manipulation of autophagy activation or inhibition in different pathological contexts, depending on clinical purpose.

Distribution and dynamics of hyphal organelles

Filamentous fungi have been very useful organisms for the investigation of organelles in eukaryotic cells. The structure and function of fungal organelles is generally very similar to that observed in animal cells. However, the nature of a "cell" in many filamentous fungi is unusual, because in many of these organisms the filaments are structured as a large syncytium. In the Ascomycota hyphae are typically a very long tube divided into different compartments by an incomplete cell wall called the septum. The pore in the middle of the septum is large enough to allow virtually all organelles to move from one hyphal compartment to another. In this review, I will look at the dynamics of this movement of organelles and describe what we know about how the structure and distribution of organelles varies from one hyphal compartment to another.

Tools to Dissect Lipid Droplet Regulation, Players, and Mechanisms

Spurred by the authors' own recent discovery of reactive metabolite-regulated nexuses involving lipid droplets (LDs), this perspective discusses the latest knowledge and multifaceted approaches toward deconstructing the function of these dynamic organelles, LD-associated localized signaling networks, and protein players. Despite accumulating knowledge surrounding protein families and pathways of conserved importance for LD homeostasis surveillance and maintenance across taxa, much remains to be understood at the molecular level. In particular, metabolic stress-triggered contextual changes in LD-proteins' localized functions, crosstalk with other organelles, and feedback signaling loops and how these are specifically rewired in disease states remain to be illuminated with spatiotemporal precision. We hope this perspective promotes an increased interest in these essential organelles and innovations of new tools and strategies to better understand context-specific LD regulation critical for organismal health.

Mitochondrial quality control in cardiomyocytes: safeguarding the heart against disease and ageing

Mitochondria are multifunctional organelles that are important for many different cellular processes, including energy production and biosynthesis of fatty acids, haem and iron-sulfur clusters. Mitochondrial dysfunction leads to a disruption in these processes, the generation of excessive reactive oxygen species, and the activation of inflammatory and cell death pathways. The consequences of mitochondrial dysfunction are particularly harmful in energy-demanding organs such as the heart. Loss of terminally differentiated cardiomyocytes leads to cardiac remodelling and a reduced ability to sustain contraction. Therefore, cardiomyocytes rely on multilayered mitochondrial quality control mechanisms to maintain a healthy population of mitochondria. Mitochondrial chaperones protect against protein misfolding and aggregation, and resident proteases eliminate damaged proteins through proteolysis. Irreparably damaged mitochondria can also be degraded through mitochondrial autophagy (mitophagy) or ejected from cells inside vesicles. The accumulation of dysfunctional mitochondria in cardiomyocytes is a hallmark of ageing and cardiovascular disease. This accumulation is driven by impaired mitochondrial quality control mechanisms and contributes to the development of heart failure. Therefore, there is a strong interest in developing therapies that directly target mitochondrial quality control in cardiomyocytes. In this Review, we discuss the current knowledge of the mechanisms involved in regulating mitochondrial quality in cardiomyocytes, how these pathways are altered with age and in disease, and the therapeutic potential of targeting mitochondrial quality control pathways in cardiovascular disease.

Deciphering significances of autophagy in the development and metabolism of adipose tissue

The mechanisms of adipose tissue activation and inactivation have been a hot topic of research in the last decade, from which countermeasures have been attempted to be found against obesity as well as other lipid metabolism-related diseases, such as type 2 diabetes mellitus and non-alcoholic fatty liver disease. Autophagy has been shown to be closely related to the regulation of adipocyte activity, which is involved in the whole process including white adipocyte differentiation/maturation and brown or beige adipocyte generation/activation. Dysregulation of autophagy in adipose tissue has been demonstrated to be associated with obesity. On this basis, we summarize the pathways and mechanisms of autophagy involved in the regulation of lipid metabolism and present a review of its pathophysiological roles in lipid metabolism-related diseases, in the hope of providing ideas for the treatment of these diseases.

Autophagy-Mediated Targeted Protein Degradation

Autophagy is an evolutionarily conserved turnover process in eukaryotes, mediating the delivery of various cellular components to lysosomes for degradation and facilitating the recycling of the breakdown products to maintain homeostasis. By harnessing this powerful autophagy-lysosomal degradation system, strategies for targeted protein degradation (TPD) have been emerging to remove specific disease-related proteins (both intracellular and cell-surface proteins) for complete elimination of their functions, bringing new insights to drug discovery. Herein, we give a brief introduction on how autophagy works followed by a focus on available small-molecule and macromolecule-based strategies for TPD mediated by autophagy.

Activating autophagy to eliminate toxic protein aggregates with small molecules in neurodegenerative diseases

Neurodegenerative diseases (NDs), such as Alzheimer disease, Parkinson disease, Huntington disease, amyotrophic lateral sclerosis, and frontotemporal dementia, are well known to pose formidable challenges for their treatment due to their intricate pathogenesis and substantial variability among patients, including differences in environmental exposures and genetic predispositions. One of the defining characteristics of NDs is widely reported to be the buildup of misfolded proteins. For example, Alzheimer disease is marked by amyloid beta and hyperphosphorylated Tau aggregates, whereas Parkinson disease exhibits α-synuclein aggregates. Amyotrophic lateral sclerosis and frontotemporal dementia exhibit TAR DNA-binding protein 43, superoxide dismutase 1, and fused-in sarcoma protein aggregates, and Huntington disease involves mutant huntingtin and polyglutamine aggregates. These misfolded proteins are the key biomarkers of NDs and also serve as potential therapeutic targets, as they can be addressed through autophagy, a process that removes excess cellular inclusions to maintain homeostasis. Various forms of autophagy, including macroautophagy, chaperone-mediated autophagy, and microautophagy, hold a promise in eliminating toxic proteins implicated in NDs. In this review, we focus on elucidating the regulatory connections between autophagy and toxic proteins in NDs, summarizing the cause of the aggregates, exploring their impact on autophagy mechanisms, and discussing how autophagy can regulate toxic protein aggregation. Moreover, we underscore the activation of autophagy as a potential therapeutic strategy across different NDs and small molecules capable of activating autophagy pathways, such as rapamycin targeting the mTOR pathway to clear α-synuclein and Sertraline targeting the AMPK/mTOR/RPS6KB1 pathway to clear Tau, to further illustrate their potential in NDs' therapeutic intervention. Together, these findings would provide new insights into current research trends and propose small-molecule drugs targeting autophagy as promising potential strategies for the future ND therapies. SIGNIFICANCE STATEMENT: This review provides an in-depth overview of the potential of activating autophagy to eliminate toxic protein aggregates in the treatment of neurodegenerative diseases. It also elucidates the fascinating interrelationships between toxic proteins and the process of autophagy of "chasing and escaping" phenomenon. Moreover, the review further discusses the progress utilizing small molecules to activate autophagy to improve the efficacy of therapies for neurodegenerative diseases by removing toxic protein aggregates.

Ultrastructural evidence for the activation of autophagy and analysis of the protective role of autophagy in goat spermatozoa under liquid storage

Liquid storage of semen is a widely used technology for promoting genetic improvement in goat breeding. The short shelf life of spermatozoa greatly limits the application of liquid storage, which urgently needs to explore the underlying regulatory factors. Autophagy as a cellular catabolic process plays critical roles in eliminating damaged material, that thus protects the function and fertilizing ability of spermatozoa. Nevertheless, the regulatory mechanisms of autophagy in goat spermatozoa under liquid storage remain unclear. In this study, the typical morphologic abnormalities and ultrastructural changes in goat spermatozoa, such as plasma membrane swollen and shrunken, acrosome exfoliation, and axoneme exposure, were observed after liquid storage at 4°C. Moreover, assessment of the formation of autophagy in liquid-stored goat spermatozoa was performed by a morphological "gold standard" of electron microscopy. Notably, a large number of vesicles with double-membrane structure indicating autophagosome were found to surround the aberrant spermatozoa, suggesting the activation of autophagy. Several proteins, such as LC3, ATG5, and p62, exhibited differential expression after liquid storage, which further validated the occurrence of autophagy in liquid-stored goat spermatozoa. Furthermore, chloroquine treatment was used to inhibit the autophagy of spermatozoa, which caused a significantly decrease in the quality of liquid-stored spermatozoa, including motility, viability, plasma membrane integrity, and acrosome integrity. Significant increase in ROS and MDA levels of spermatozoa and significant decrease in Ca2+ influx and protein tyrosine phosphorylation of spermatozoa were also detected after chloroquine-induced autophagy inhibition. The ultrastructural observation of double-membrane autophagosome provides strong evidences for the activation of autophagy in goat spermatozoa under liquid storage. The inhibition of autophagy mediated by chloroquine indicated that autophagy plays vital roles in the survival of spermatozoa. These results facilitate understanding the activation of autophagy in spermatozoa and provide valuable references for uncovering the underlying regulatory mechanisms of liquid storage of goat spermatozoa.

Redox regulation: mechanisms, biology and therapeutic targets in diseases

Redox signaling acts as a critical mediator in the dynamic interactions between organisms and their external environment, profoundly influencing both the onset and progression of various diseases. Under physiological conditions, oxidative free radicals generated by the mitochondrial oxidative respiratory chain, endoplasmic reticulum, and NADPH oxidases can be effectively neutralized by NRF2-mediated antioxidant responses. These responses elevate the synthesis of superoxide dismutase (SOD), catalase, as well as key molecules like nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione (GSH), thereby maintaining cellular redox homeostasis. Disruption of this finely tuned equilibrium is closely linked to the pathogenesis of a wide range of diseases. Recent advances have broadened our understanding of the molecular mechanisms underpinning this dysregulation, highlighting the pivotal roles of genomic instability, epigenetic modifications, protein degradation, and metabolic reprogramming. These findings provide a foundation for exploring redox regulation as a mechanistic basis for improving therapeutic strategies. While antioxidant-based therapies have shown early promise in conditions where oxidative stress plays a primary pathological role, their efficacy in diseases characterized by complex, multifactorial etiologies remains controversial. A deeper, context-specific understanding of redox signaling, particularly the roles of redox-sensitive proteins, is critical for designing targeted therapies aimed at re-establishing redox balance. Emerging small molecule inhibitors that target specific cysteine residues in redox-sensitive proteins have demonstrated promising preclinical outcomes, setting the stage for forthcoming clinical trials. In this review, we summarize our current understanding of the intricate relationship between oxidative stress and disease pathogenesis and also discuss how these insights can be leveraged to optimize therapeutic strategies in clinical practice.

Murine Leukemia Virus GlycoGag Antagonizes SERINC5 via ER-phagy Receptor RETREG1

Serine incorporator 5 (SERINC5) is a host restriction factor that targets certain enveloped viruses, including human immunodeficiency virus type 1 (HIV-1) and murine leukemia virus (MLV). It integrates into the viral envelope from the cell surface, inhibiting viral entry. SERINC5 is transported to the cell surface via polyubiquitination, while a single K130R mutation retains it in the cytoplasm. Both HIV-1 Nef and MLV glycoGag proteins antagonize SERINC5 by reducing its expression in producer cells. Here, we report that MLV glycoGag employs selective autophagy to downregulate SERINC5, demonstrating a more potent mechanism for decreasing its cell surface expression. Although glycoGag is a type II integral membrane protein, it primarily localizes to the cytoplasm and undergoes rapid proteasomal degradation. Employing the K130R mutant, we show that Nef, primarily associated with the plasma membrane, downregulates SERINC5 only after it has trafficked to the cell surface, whereas glycoGag can reduce its expression before reaching the plasma membrane while still in the cytoplasm. Nonetheless, an interaction with SERINC5 stabilizes and recruits glycoGag to the plasma membrane, enabling it to downregulate SERINC5 from the cell surface. Through affinity-purified mass spectrometry analysis combined with CRISPR/Cas9 knockouts, we find that glycoGag's activity depends on reticulophagy regulator 1 (RETREG1), an ER-phagy receptor. Further knockout experiments of critical autophagy genes demonstrate that glycoGag downregulates cytoplasmic SERINC5 via micro-ER-phagy. These findings provide crucial new insights into the ongoing arms race between retroviruses and SERINC5 during infection.

TAX1BP1-dependent autophagic degradation of STING1 impairs anti-tumor immunity

The activation of STING1 can lead to the production and secretion of cytokines, initiating antitumor immunity. Here, we screened an ion channel ligand library and identified tetrandrine, a bis-benzylisoquinoline alkaloid, as an immunological adjuvant that enhances antitumor immunity by preventing the autophagic degradation of the STING1 protein. This tetrandrine effect is independent of its known function as a calcium or potassium channel blocker. Instead, tetrandrine inhibits lysosomal function, impairing cathepsin maturation, and autophagic degradation. Proteomic analysis of lysosomes identified TAX1BP1 as a novel autophagic receptor for the proteolysis of STING1. TAX1BP1 recognizes STING1 through the physical interaction of its coiled-coil domain with the cyclic dinucleotide binding domain of STING1. Systematic mutation of lysine (K) residues revealed that K63-ubiquitination of STING1 at the K224 site ignites TAX1BP1-dependent STING1 degradation. Combined treatment with tetrandrine and STING1 agonists promotes antitumor immunity by converting "cold" pancreatic cancers into "hot" tumors. This process is associated with enhanced cytokine release and increased infiltration of cytotoxic T-cells into the tumor microenvironment. The antitumor immunity mediated by tetrandrine and STING1 agonists is limited by neutralizing antibodies to the type I interferon receptor or CD8+ T cells. Thus, these findings establish a potential immunotherapeutic strategy against pancreatic cancer by preventing the autophagic degradation of STING1.

Oxymatrine alleviates ALD-induced cardiac hypertrophy by regulating autophagy via activation Nrf2/SIRT3 signaling pathway

BACKGROUND

Cardiac hypertrophy is a prevalent early pathological manifestation in various cardiovascular diseases, lacking effective interventions to impede its progression. Although oxymatrine (OMT) has shown potential benefits for cardiac function, its therapeutic efficacy and mechanism in cardiac hypertrophy remain incompletely understood. Notably, mitochondrial damage and dysregulated autophagy are pivotal pathogenic mechanisms in cardiac hypertrophy.

PURPOSE

We investigate the pharmacological characteristics and mechanism of OMT in mitochondrial function and autophagy in cardiac hypertrophy.

STUDY DESIGN AND METHODS

A murine model of cardiac hypertrophy was induced by aldosterone in combination with high-salt drinking water, while primary cardiomyocyte hypertrophy was induced by aldosterone in vitro. Cardiac hypertrophy was assessed using echocardiography and histopathological staining. Autophagosomes and mitochondrial morphology were visualized by transmission electron microscopy. Levels of reactive oxygen species (ROS), malondialdehyde (MDA), and adenosine triphosphate (ATP) were quantified using commercial kits. The binding affinity of OMT with Nrf2 was assessed through molecular docking. Furthermore, adenovirus, agonists, and inhibitors were employed to modulate Nrf2, followed by quantitative real-time polymerase chain reaction (qRT-PCR), immunoblotting, co-immunoprecipitation, chromatin immunoprecipitation, immunohistochemistry, and cellular thermal shift assay.

RESULTS

OMT effectively attenuated aldosterone-induced cardiac hypertrophy both in vivo and in vitro. OMT promoted the activation of Nrf2, leading to elevated SIRT3 expression and enhanced autophagolysosome fusion, thereby modulating mitophagy and improving mitochondrial function. Moreover, the cardioprotective effects of OMT were abolished upon silencing or inhibition of Nrf2. OMT binds to Nrf2, facilitating its dissociation and nuclear translocation.

CONCLUSION

OMT activates Nrf2, consequently enhancing SIRT3 transcription, restoring autophagic flux, and preserving mitochondrial integrity, thereby mitigating aldosterone-induced cardiac hypertrophy. In summary, our study is the first to discover and confirm that OMT can stabilize Nrf2, promoting its activation and subsequently up-regulating SIRT3, which in turn facilitates mitochondrial autophagy. Additionally, PARKIN appears to play a key role in SIRT3-mediated regulation of mitophagy, warranting further investigation.

Secernin-2 Stabilizes Histone Methyltransferase KMT2C to Suppress Progression and Confer Therapeutic Sensitivity to PARP Inhibition in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a difficulty and bottleneck in the clinical treatment of breast cancer due to a lack of effective therapeutic targets. Herein, we first report that secernin 2 (SCRN2), an uncharacterized gene in human cancer, acts as a novel tumor suppressor in TNBC to inhibit cancer progression and enhance therapeutic sensitivity to poly(ADP-ribose) polymerase (PARP) inhibition both in vitro and in vivo. SCRN2 is downregulated in TNBC through chaperone-mediated autophagic degradation, and its downregulation is associated with poor patient prognosis. Moreover, SCRN2 impedes the proteasomal degradation of histone-lysine N-methyltransferase 2C (KMT2C) by recruiting Bcl2-associated athanogene 2 to block the interaction of KMT2C with E3 ubiquitin-protein ligase CHIP. Consistently, SCRN2 transcriptionally activates Bcl2-modifying factor by amplifying histone H3 monomethylation at lysine 4 at its enhancer, thereby inducing intrinsic apoptosis. Notably, KMT2C knockdown restores the impaired TNBC progression caused by SCRN2 overexpression both in vitro and in vivo. Furthermore, SCRN2 decreases the expression of key DNA repair-related genes and induces endogenous DNA damage, thus conferring therapeutic sensitivity of TNBC cells to PARP inhibition.   Collectively, these findings identify SCRN2 as a novel suppressor of TNBC, reveal its mechanism of action, and highlight its potential role in TNBC therapy.

Cargo hitchhiking autophagy - a hybrid autophagy pathway utilized in yeast

Macroautophagy is a catabolic process that maintains cellular homeostasis by recycling intracellular material through the use of double-membrane vesicles called autophagosomes. In turn, autophagosomes fuse with vacuoles (in yeast and plants) or lysosomes (in metazoans), where resident hydrolases degrade the cargo. Given the conservation of autophagy, Saccharomyces cerevisiae is a valuable model organism for deciphering molecular details that define macroautophagy pathways. In yeast, macroautophagic pathways fall into two subclasses: selective and nonselective (bulk) autophagy. Bulk autophagy is predominantly upregulated following TORC1 inhibition, triggered by nutrient stress, and degrades superfluous random cytosolic proteins and organelles. In contrast, selective autophagy pathways maintain cellular homeostasis when TORC1 is active by degrading damaged organelles and dysfunctional proteins. Here, selective autophagy receptors mediate cargo delivery to the vacuole. Now, two groups have discovered a new hybrid autophagy mechanism, coined cargo hitchhiking autophagy (CHA), that uses autophagic receptor proteins to deliver selected cargo to phagophores built in response to nutrient stress for the random destruction of cytosolic contents. In CHA, various autophagic receptors link their cargos to lipidated Atg8, located on growing phagophores. In addition, the sorting nexin heterodimer Snx4-Atg20 assists in the degradation of cargo during CHA, possibly by aiding the delivery of cytoplasmic cargos to phagophores and/or by delaying the closure of expanding phagophores. This review will outline this new mechanism, also known as Snx4-assisted autophagy, that degrades an assortment of cargos in yeast, including transcription factors, glycogen, and a subset of ribosomal proteins.

Tau degradation in Alzheimer's disease: Mechanisms and therapeutic opportunities

In Alzheimer's disease (AD), tau undergoes abnormal post-translational modifications and aggregations. Impaired intracellular degradation pathways further exacerbate the accumulation of pathological tau. A new strategy - targeted protein degradation - recently emerged as a modality in drug discovery where bifunctional molecules bring the target protein close to the degradation machinery to promote clearance. Since 2016, this strategy has been applied to tau pathologies and attracted broad interest in academia and the pharmaceutical industry. However, a systematic review of recent studies on tau degradation mechanisms is lacking. Here we review tau degradation mechanisms (the ubiquitin-proteasome system and the autophagy-lysosome pathway), their dysfunction in AD, and tau-targeted degraders, such as proteolysis-targeting chimeras and autophagy-targeting chimeras. We emphasize the need for a continuous exploration of tau degradation mechanisms and provide a future perspective for developing tau-targeted degraders, encouraging researchers to work on new treatment options for AD patients. HIGHLIGHTS: Post-translational modifications, aggregation, and mutations affect tau degradation. A vicious circle exists between impaired degradation pathways and tau pathologies. Ubiquitin plays an important role in complex degradation pathways. Tau-targeted degraders provide promising strategies for novel AD treatment.

Selective clearance of aberrant membrane proteins by TORC1-mediated micro-ER-phagy

Aberrant accumulation and clearance of membrane proteins is associated with disease. Membrane proteins are inserted first to the endoplasmic reticulum (ER). During normal growth, two quality control (QC) processes, ER-associated degradation and macro-ER-phagy, deliver misfolded and excess membrane proteins for degradation in the proteasome and lysosome, respectively. We show that in yeast during normal growth, ER-QC is constitutive, since none of the stress-induced signaling pathways-nutritional, proteotoxic, or heat-are involved. In mutant cells defective in ER-QC, misfolded or excess proteins accumulate and nutritional stress, but not proteotoxic or heat stress, can stimulate their clearance. Early during nutritional stress, clearance occurs in the lysosome through a selective micro-ER-phagy pathway dependent on the ubiquitin ligase Rsp5, its Ssh4 adaptor, and ESCRT. In contrast, only a fraction of normal membrane proteins is degraded much later via macro-autophagy. Because the pathways explored here are conserved, nutritional stress emerges as a possible way for clearing disease-associated membrane proteins.

Visualizing bulk autophagy in vivo by tagging endogenous LC3B

Macroautophagy/autophagy plays a crucial role in maintaining cellular and organismal health, making the measurement of autophagy flux in vivo essential for its study. Current tools often depend on the overexpression of autophagy probes. In this study, we developed a knock-in mouse model, termed tfLC3-KI, by inserting a tandem fluorescent tag coding sequence into the native Map1lc3b gene locus. We found that tfLC3-KI mice exhibit optimal expression of mRFP-eGFP-LC3B, allowing for convenient measurement of autophagic structures and flux at single-cell resolution, both in vivo and in primary cell cultures. Additionally, we compared autophagy in neurons and glial cells across various brain regions between tfLC3-KI mice and CAG-tfLC3 mice, the latter overexpressing the probe under the strong CMV promoter. Finally, we used tfLC3-KI mice to map the spatial and temporal dynamics of basal autophagy activity in the reproductive system. Our findings highlight the value of the tfLC3-KI mouse model for investigating autophagy flux in vivo and demonstrate the feasibility of tagging endogenous proteins to visualize autophagic structures and flux in both bulk and selective autophagy research in vivo.Abbreviation: BafA1: bafilomycin A1; CQ: chloroquine; EBSS: Earle's balanced salt solution; Es: elongating spermatids; HPF: hippocampalformation; HY: hypothalamus; LCs: leydig cells; OLF: olfactory areas; PepA: pepstatin A; Rs: round spermatids; SCs: sertoli cells; Spc: spermatocytes; Spg: spermatogonia; tfLC3: tandem fluorescently tagged mRFP-eGFP-LC3; TH: thalamus.

Autophagy in Tissue Repair and Regeneration

Autophagy is a cellular recycling system that, through the sequestration and degradation of intracellular components regulates multiple cellular functions to maintain cellular homeostasis and survival. Dysregulation of autophagy is closely associated with the development of physiological alterations and human diseases, including the loss of regenerative capacity. Tissue regeneration is a highly complex process that relies on the coordinated interplay of several cellular processes, such as injury sensing, defense responses, cell proliferation, differentiation, migration, and cellular senescence. These processes act synergistically to repair or replace damaged tissues and restore their morphology and function. In this review, we examine the evidence supporting the involvement of the autophagy pathway in the different cellular mechanisms comprising the processes of regeneration and repair across different regenerative contexts. Additionally, we explore how modulating autophagy can enhance or accelerate regeneration and repair, highlighting autophagy as a promising therapeutic target in regenerative medicine for the development of autophagy-based treatments for human diseases.

Limiting cap-dependent translation increases 20S proteasomal degradation and protects the proteomic integrity in autophagy-deficient skeletal muscle

Postmitotic skeletal muscle critically depends on tightly regulated protein degradation to maintain proteomic stability. Impaired macroautophagy/autophagy-lysosomal or ubiquitin-proteasomal protein degradation causes the accumulation of damaged proteins, ultimately accelerating muscle dysfunction with age. While in vitro studies have demonstrated the complementary nature of these systems, their interplay at the organism levels remains poorly understood. Here, our study reveals novel insights into this complex relationship in autophagy-deficient skeletal muscle. We demonstrated that despite a compensatory increase in proteasome level in response to autophagy impairment, 26S proteasome activity was not proportionally enhanced in autophagy-deficient skeletal muscle. This functional deficit was partly attributed to reduced ATP levels to fuel the 26S proteasome. Remarkably, we found that activation of EIF4EBP1, a crucial inhibitor of cap-dependent translation, restored and even augmented proteasomal function through dual mechanisms. First, genetically activating EIF4EBP1 enhanced both ATP-dependent 26S proteasome and ATP-independent 20S proteasome activities, thereby expanding overall protein degradation capacity. Second, EIF4EBP1 activation caused muscle fiber transformation and increased mitochondrial biogenesis, thus replenishing ATP levels for 26S proteasome activation. Notably, the improved performance of the 20S proteasome in EIF4EBP1-activated skeletal muscle was attributed to an increased abundance of the immunoproteasome, a subtype specially adapted to function under oxidative stress conditions. This dual action of EIF4EBP1 activation preserved proteomic integrity in autophagy-deficient skeletal muscle. Our findings uncover a novel role of EIF4EBP1 in improving protein quality control, presenting a promising therapeutic strategy for autophagy-related muscular disorders and potentially other conditions characterized by proteostatic imbalance.Abbreviations: 3-MA: 3-methyladenine; ACAC/ACC: acetyl-Coenzyme A carboxylase; AMPK: AMP-activated protein kinase; ATG5: autophagy related 5; ATG7: autophagy related 7; ATP: adenosine triphosphate; ATP5F1A/ATP5A: ATP synthase F1 subunit alpha; CKM-Cre: creatine kinase, muscle-Cre; CMA: chaperone-mediated autophagy; CTSB: cathepsin B; CTSK: cathepsin K; CTSL: cathepsin L; CUL3: cullin 3; EDL: extensor digitorum longus; EIF4E: eukaryotic translation initiation factor 4E; EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; EIF4F: eukaryotic translation initiation factor 4F complex; FBXO32/ATROGIN1/MAFbx: F-box protein 32; GFP: green fluorescent protein; IFNG/IFN-γ: interferon gamma; KEAP1: kelch-like ECH-associated protein 1; LAMP1: lysosomal-associated membrane protein 1; LAMP2: lysosomal-associated membrane protein 2; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MEF: mouse embryonic fibroblast; Myl1/Mlc1f-Cre: myosin, light polypeptide 1 (promoter driving Cre recombinase); mRFP: monomeric red fluorescent protein; MTOR: mechanistic target of rapamycin kinase; MTORC1: MTOR complex 1; NFE2L1/NRF1: nuclear factor, erythroid derived 2, like 1; NFE2L2/NRF2: nuclear factor, erythroid derived 2, like 2; NFKB1/NFκB1: nuclear factor of kappa light polypeptide gene enhancer in B cells 1, p105; OXPHOS: oxidative phosphorylation; PPARGC1A/PGC1α: peroxisome proliferator activated receptor, gamma, coactivator 1 alpha; PSMB5: proteasome (prosome, macropain) subunit, beta type 5; PSMB6: proteasome (prosome, macropain) subunit, beta type 6; PSMB7: proteasome (prosome, macropain) subunit, beta type 7; PSMB8: proteasome (prosome, macropain) subunit, beta type 8 (large multifunctional peptidase 7); PSMB9: proteasome (prosome, macropain) subunit, beta type 9 (large multifunctional peptidase 2); PSMB10: proteasome (prosome, macropain) subunit, beta type 10; PSME1: proteasome (prosome, macropain) activator subunit 1 (PA28 alpha); PSME2: proteasome (prosome, macropain) activator subunit 2 (PA28 beta); RBX1: ring-box 1; SQSTM1/p62: sequestosome 1; SREBF1/SREBP1: sterol regulatory element binding transcription factor 1; STAT3: signal transducer and activator of transcription 3; TRIM63/MURF1: tripartite motif-containing 63; ULK1: unc-51 like kinase 1; UPS: ubiquitin-proteasome system.

Upregulation of Autophagy During the Differentiation of Primary Human Term Cytotrophoblast Cells into Syncytial Cells: Ultrastructural Analysis

The villous trophoblast cells are of fundamental importance because they fulfill a variety of functions that are vital for the growth of the fetus and the maintenance of pregnancy. A simple in vitro villous trophoblast cell model that grows on standard tissue culture plates has been utilized for various functional studies on villous trophoblast cells. Despite the potential value of incorporating electron microscopy analysis in reports on functional analysis of primary human trophoblast cells, electron microscopy analysis is exclusively ancillary to functional analysis in previous publications. In the context of autophagy research of villous trophoblast cells using primary trophoblast cells, a detailed ultrastructural analysis of autophagy flux using electron microscopy is imperative; however, it has not been conducted to date. In this study, we isolated term villous trophoblast cells (i.e., cytotrophoblast cells, CTB cells) using the most up-to-date isolation method for isolating pure CTB cells from human term placenta and investigated the ultrastructural dynamic process of autophagy of cultured CTB cells by means of transmission electron microscopy. The initial 6 h culture resulted in CTB cell aggregation; however, the majority of CTB cells did not differentiate into syncytial cells. In contrast, after 72 h, CTB cells exhibited a promotion of differentiation into syncytial cells. The electron microscopy analysis revealed the upregulation of autophagy and visualized unique autophagic profiles during differentiation into syncytial cells, which exhibited perinuclear accumulation of extremely large autophagosomes/autolysosomes. This study provides novel insights into the reproductive biology of primary trophoblast cells, thereby demonstrating the substantial value of primary trophoblast cells as research resources.

Insights into the different mechanisms of Autophagy and Apoptosis mediated by Morbilliviruses

Viruses are obligate intracellular parasites that have co-evolved with the host. During the course of evolution, viruses have acquired abilities to abrogate the host's immune responses by modulating the host proteins which play a pivotal role in various biological processes. One such process is the programmed cell death in virus-infected cells, which can occur via autophagy or apoptosis. Morbilliviruses are known to modulate both autophagy and apoptosis. Upon infecting a cell, the morbilliviruses can utilize autophagosomes as their nest and delay the host defense apoptotic response, and/or can promote apoptosis to escalate the virus dissemination. Moreover, there is an active interplay between these two pathways which eventually decides the fate of a virus-infected cell. Recent advances in our understanding of these processes provide a potential rationale to further explore morbilliviruses for therapeutic purposes.

In Situ Transformable Nanoparticle Effectively Suppresses Bladder Cancer by Damaging Mitochondria and Blocking Mitochondrial Autophagy Flux

Tumor therapeutic strategies based on mitochondrial damage have become an emerging trend. However, the low drug delivery efficiency caused by lysosomal sequestration and the activation of protective mitochondrial autophagy severely restricts the therapeutic efficacy. Herein, an in situ transformable nanoparticle named KCKT is developed to promote lysosomal escape and directly damage mitochondria while blocking mitochondrial autophagy. KCKT exhibits acid responsiveness for precise self-assembly into nanofibers within the lysosomes of cancer cells. The massive accumulation of nanofibers and excessive production of reactive oxygen species (ROS) under sonodynamic therapy synergistically induce lysosomal damage. This facilitates the escape of nanofibers from lysosomal sequestration, thereby enhancing drug delivery. Subsequently, the escaped nanofibers specifically aggregate around the mitochondria for long-term retention and generate ROS under ultrasound irradiation to induce mitochondrial damage. Notably, due to lysosomal dysfunction, damaged mitochondria cannot be cleared by autophagy, further aggravating oxidative damage. These results reveal that KCKT effectively improves drug delivery and mitochondria-targeted therapy efficiency by blocking protective autophagy. These findings hold significant potential for advancing the field of mitochondria-targeted therapy.

Regulation of autophagy and cellular signaling through non-histone protein methylation

Autophagy is a highly conserved catabolic pathway that is precisely regulated and plays a significant role in maintaining cellular metabolic balance and intracellular homeostasis. Abnormal autophagy is directly linked to the development of various diseases, particularly immune disorders, neurodegenerative conditions, and tumors. The precise regulation of proteins is crucial for proper cellular function, and post-translational modifications (PTMs) are key epigenetic mechanisms in the regulation of numerous biological processes. Multiple proteins undergo PTMs that influence autophagy regulation. Methylation modifications on non-histone lysine and arginine residues have been identified as common PTMs critical to various life processes. This paper focused on the regulatory effects of non-histone methylation modifications on autophagy, summarizing related research on signaling pathways involved in autophagy-related non-histone methylation, and discussing current challenges and clinical significance. Our review concludes that non-histone methylation plays a pivotal role in the regulation of autophagy and its associated signaling pathways. Targeting non-histone methylation offers a promising strategy for therapeutic interventions in diseases related to autophagy dysfunction, such as cancer and neurodegenerative disorders. These findings provide a theoretical basis for the development of non-histone-methylation-targeted drugs for clinical use.

Regulated cell death in acute myocardial infarction: Molecular mechanisms and therapeutic implications

Acute myocardial infarction (AMI), primarily caused by coronary atherosclerosis, initiates a series of events that culminate in the obstruction of coronary arteries, resulting in severe myocardial ischemia and hypoxia. The subsequent myocardial ischemia/reperfusion (I/R) injury further aggravates cardiac damage, leading to a decline in heart function and the risk of life-threatening complications. The complex interplay of multiple regulated cell death (RCD) pathways plays a pivotal role in the pathogenesis of AMI. Each RCD pathway is orchestrated by a symphony of molecular regulatory mechanisms, highlighting the dynamic changes and critical roles of key effector molecules. Strategic disruption or inhibition of these molecular targets offers a tantalizing prospect for mitigating or even averting the onset of RCD, thereby limiting the extensive loss of cardiomyocytes and the progression of detrimental myocardial fibrosis. This review systematically summarizes the mechanisms underlying various forms of RCD, provides an in-depth exploration of the pathogenesis of AMI through the lens of RCD, and highlights a range of promising therapeutic targets that hold the potential to revolutionize the management of AMI.

The 2-aminoadipic acid (2-AAA) regulates grass carp ULK2 to inhibit GCRV replication

Grass carp is an important commercial fish in China that is plagued by various diseases, especially the hemorrhagic disease induced by grass carp reovirus (GCRV). Autophagy, a highly conserved biological process among eukaryotes, is pivotal in maintaining cellular homeostasis and managing various stressors, including viral infections. Uncoordinated (Unc) 51-like kinase 2 (ULK2) is considered an initiator of the autophagic process. In this study, we successfully cloned and isolated the ULK2 gene from grass carp. We observed that its expression levels were markedly altered following exposure to GCRV or pathogen-associated molecular patterns (PAMPs). Overexpression of CiULK2 in grass carp ovary cells (GCO) promoted GCRV replication. Conversely, CiULK2 knockdown resulted in inhibited viral loads compared to the control group. Moreover, we also reveal that 2-aminoadipic acid (2-AAA), a representative autophagy related metabolite, can inhibit autophagy and viral replication. Notably, these roles of CiULK2 in autophagy and GCRV replication were reversed upon treatment with the 2-AAA. Collectively, our findings demonstrate the 2-AAA regulates CiULK2 to inhibit GCRV replication.

The protective role of baicalin regulation of autophagy in cancers

Autophagy is a conservative process of self degradation, in which abnormal organelles, proteins and other macromolecules are encapsulated and transferred to lysosomes for subsequent degradation. It maintains the intracellular balance, and responds to cellular conditions such as hunger or stress. To date, there are mainly three types of autophagy: macroautophagy, microautophagy and chaperone-mediated autophagy. Autophagy plays a key role in regulating multiple physiological and pathological processes, such as cell metabolism, development, energy homeostasis, cell death and hunger adaptation, and so on. Increasing evidence indicates that autophagy dysfunction participates in many kinds of cancers, such as liver cancer, pancreatic cancer, prostate cancer, and so on. However, the relevant mechanisms are not yet fully understood. Baicalin is a natural flavonoid compound extracted from the traditional Chinese medicine Scutellaria baicalensis. The research has shown that after oral or intravenous administration of baicalin, it is delivered to various organs through the systemic circulation, with the highest volume in the kidneys and lungs. More and more evidence suggests that baicalin has antioxidant, anticancer, anti-inflammatory, anti-apoptotic, immunomodulatory and antiviral effects. Therefore, baicalin plays an important role in various diseases, such as cancers, lung diseases, liver diseases, cardiovascular diseases, ans so on. However, the relevant mechanisms have not yet been fully clear. Recently, increasing evidence indicates that baicalin participates in different cancer by regulating autophagy. Herein, we reviewed the current knowledge about the role and mechanism of baicalin regulation of autophagy in multiple types of cancers to lay the theoretical foundation for future related researches.

ESCRT elicits vacuolar fission in the absence of Vps4 in budding yeast

In budding yeast, endosomal sorting complex required for transport (ESCRT) mediates microautophagy by vacuolar membrane invagination into the vacuolar lumen, followed by Vps4-assisted membrane constriction and abscission. Here, we show that ESCRT elicits vacuolar fission in the absence of Vps4 after nutrient starvation, although vacuolar fusion is facilitated in wild-type cells in these conditions. ESCRT mediated vacuolar membrane invagination in vps4Δ cells, thereby causing vacuolar fission. It is known that vacuolar fission requires phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2) and β-propellers that bind polyphosphoinositides (PROPPINs), PI(3,5)P2-binding proteins. However, PROPPIN, but not PI(3,5)P2, was dispensable for the ESCRT-mediated vacuolar fragmentation. Finally, we showed evidence that microlipophagy triggers vacuolar fission. Thus, disruption of the coordinated sequence of ESCRT-Vps4 operations in microautophagy leads to vacuolar fragmentation. This study provides insight into the ESCRT-Vps4 axis-dependent cellular disfunctions and related diseases.

Periodontopathogen-Related Cell Autophagy-A Double-Edged Sword

The periodontium is a highly organized ecosystem, and the imbalance between oral microorganisms and host defense leads to periodontal diseases. The periodontal pathogens, mainly Gram-negative anaerobic bacteria, colonize the periodontal niches or enter the blood circulation, resulting in periodontal tissue destruction and distal organ damage. This phenomenon links periodontitis with various systemic conditions, including cardiovascular diseases, malignant tumors, steatohepatitis, and Alzheimer's disease. Autophagy is an evolutionarily conserved cellular self-degradation process essential for eliminating internalized pathogens. Nowadays, increasing studies have been carried out in cells derived from periodontal tissues, immune system, and distant organs to investigate the relationship between periodontal pathogen infection and autophagy-related activities. On one hand, as a vital part of innate and adaptive immunity, autophagy actively participates in host resistance to periodontal bacterial infection. On the other, certain periodontal pathogens exploit autophagic vesicles or pathways to evade immune surveillance, therefore achieving survival within host cells. This review provides an overview of the autophagy process and focuses on periodontopathogen-related autophagy and their involvements in cells of different tissue origins, so as to comprehensively understand the role of autophagy in the occurrence and development of periodontal diseases and various periodontitis-associated systemic illnesses.

Recycle, repair, recover: the role of autophagy in modulating skeletal muscle repair and post-exercise recovery

Skeletal muscle is a highly plastic tissue that can adapt relatively rapidly to a range of stimuli. In response to novel mechanical loading, e.g. unaccustomed resistance exercise, myofibers are disrupted and undergo a period of ultrastructural remodeling to regain full physiological function, normally within 7 days. The mechanisms that underpin this remodeling are believed to be a combination of cellular processes including ubiquitin-proteasome/calpain-mediated degradation, immune cell infiltration, and satellite cell proliferation/differentiation. A relatively understudied system that has the potential to be a significant contributing mechanism to repair and recovery is the autophagolysosomal system, an intracellular process that degrades damaged and redundant cellular components to provide constituent metabolites for the resynthesis of new organelles and cellular structures. This review summarizes our current understanding of the autophagolysosomal system in the context of skeletal muscle repair and recovery. In addition, we also provide hypothetical models of how this system may interact with other processes involved in skeletal muscle remodeling and provide avenues for future research to improve our understanding of autophagy in human skeletal muscle.

Canonical and noncanonical autophagy: involvement in Parkinson's disease

Autophagy is the major degradation process in cells and is involved in a variety of physiological and pathological functions. While macroautophagy, which employs a series of molecular cascades to form ATG8-coated double membrane autophagosomes for degradation, remains the well-known type of canonical autophagy, microautophagy and chaperon-mediated autophagy have also been characterized. On the other hand, recent studies have focused on the functions of autophagy proteins beyond intracellular degradation, including noncanonical autophagy, also known as the conjugation of ATG8 to single membranes (CASM), and autophagy-related extracellular secretion. In particular, CASM is unique in that it does not require autophagy upstream mechanisms, while the ATG8 conjugation system is involved in a manner different from canonical autophagy. There have been many reports on the involvement of these autophagy-related mechanisms in neurodegenerative diseases, with Parkinson's disease (PD) receiving particular attention because of the important roles of several causative and risk genes, including LRRK2. In this review, we will summarize and discuss the contributions of canonical and noncanonical autophagy to cellular functions, with a special focus on the pathogenesis of PD.

Mammalian nucleophagy: process and function

The nucleus is a highly specialized organelle that houses the cell's genetic material and regulates key cellular activities, including growth, metabolism, protein synthesis, and cell division. Its structure and function are tightly regulated by multiple mechanisms to ensure cellular integrity and genomic stability. Increasing evidence suggests that nucleophagy, a selective form of autophagy that targets nuclear components, plays a critical role in preserving nuclear integrity by clearing dysfunctional nuclear materials such as nuclear proteins (lamins, SIRT1, and histones), DNA-protein crosslinks, micronuclei, and chromatin fragments. Impaired nucleophagy has been implicated in aging and various pathological conditions, including cancer, neurodegeneration, autoimmune disorders, and neurological injury. In this review, we focus on nucleophagy in mammalian cells, discussing its mechanisms, regulation, and cargo selection, as well as evaluating its therapeutic potential in promoting human health and mitigating disease.Abbreviations: 5-FU: 5-fluorouracil; AMPK, AMP-activated protein kinase; ATG, autophagy related; CMA, chaperone-mediated autophagy; DRPLA: dentatorubral-pallidoluysian atrophy; ER, endoplasmic reticulum; ESCRT: endosomal sorting complex required for transport; HOPS, homotypic fusion and vacuole protein sorting; LIR: LC3-interacting region; MEFs: mouse embryonic fibroblasts; mRNA: messenger RNA; MTORC1: mechanistic target of rapamycin kinase complex 1; PCa: prostate cancer; PE: phosphatidylethanolamine; PI3K, phosphoinositide 3-kinase; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; rRNA: ribosomal RNA; SCI: spinal cord injury; SCLC: small cell lung cancer; SNARE: soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SupraT: supraphysiological levels of testosterone; TOP1cc: TOP1 cleavage complexes.

Microautophagy in cereal grains: protein storage or degradation?

Recent research indicates an involvement of microautophagy in the uptake of seed storage proteins (SSPs) into the plant-specific protein storage vacuole (PSV), particularly in cereal grains. However, because microautophagy plays a vital role in cellular homeostasis by degrading and recycling cellular components, we question whether it is a suitable term for a process involved in long-term storage. Additionally, because fission-type microautophagy shares mechanistic similarities with the intraluminal vesicle (ILV) formation of multivesicular bodies (MVBs), we draw parallels between microautophagy and membrane remodeling facilitated by the endosomal sorting complex required for transport (ESCRT). Finally, we propose that the complex structure of cereal endosperm is an optimal tissue to study microautophagy in a plant- and tissue-specific context to decipher its molecular regulation in anabolism and catabolism.

Two birds with one stone: natural polyphenols boosted periodontitis treatment of chlorhexidine via reducing toxicity and regulating microenvironments

Chlorhexidine (CHX) is considered the gold standard for controlling periodontal plaque and has been extensively used as a topical agent in treating periodontitis. Nevertheless, the practical clinical application of CHX is still constrained by the inherent limitations of its properties, including toxicity, inadequate biofilm scavenging capacity, and single biological effect. In this study, polyphenolic epigallocatechin gallate (EGCG) has been employed to integrate with CHX to form an EGCG-CHX nanoplatform via a facile one-pot method. Due to the dynamic bonding between EGCG and CHX, the EGCG-CHX nanoparticles (NPs) show reduced toxicity and excellent response release behavior. Moreover, a series of in vitro and in vivo studies demonstrated that the EGCG-CHX NPs significantly enhanced the antibiofilm, antioxidative, anti-inflammatory, and autophagic flux activation effects of CHX, ultimately achieving an improved therapeutic effect on periodontitis. This study successfully developed a strategy boosting the efficiency of CHX for periodontitis treatment.

Autophagy and Mitophagy in Diabetic Kidney Disease-A Literature Review

Autophagy and mitophagy are critical cellular processes that maintain homeostasis by removing damaged organelles and promoting cellular survival under stress conditions. In the context of diabetic kidney disease, these mechanisms play essential roles in mitigating cellular damage. This review provides an in-depth analysis of the recent literature on the relationship between autophagy, mitophagy, and diabetic kidney disease, highlighting the current state of knowledge, existing research gaps, and potential areas for future investigations. Diabetic nephropathy (DN) is traditionally defined as a specific form of kidney disease caused by long-standing diabetes, characterized by the classic histological lesions in the kidney, including mesangial expansion, glomerular basement membrane thickening, nodular glomerulosclerosis (Kimmelstiel-Wilson nodules), and podocyte injury. Clinical markers for DN are albuminuria and the gradual decline in glomerular filtration rate (GFR). Diabetic kidney disease (DKD) is a broader and more inclusive term, for all forms of chronic kidney disease (CKD) in individuals with diabetes, regardless of the underlying pathology. This includes patients who may have diabetes-associated kidney damage without the typical histological findings of diabetic nephropathy. It also accounts for patients with other coexisting kidney diseases (e.g., hypertensive nephrosclerosis, ischemic nephropathy, tubulointerstitial nephropathies), even in the absence of albuminuria, such as a reduction in GFR.

Autophagy, aging, and age-related neurodegeneration

Autophagy is a conserved mechanism that degrades damaged or superfluous cellular contents and enables nutrient recycling under starvation conditions. Many neurodegeneration-associated proteins are autophagy substrates, and autophagy upregulation ameliorates disease in many animal models of neurodegeneration by enhancing the clearance of toxic proteins, proinflammatory molecules, and dysfunctional organelles. Autophagy inhibition also induces neuronal and glial senescence, a phenomenon that occurs with increasing age in non-diseased brains as well as in response to neurodegeneration-associated stresses. However, aging and many neurodegeneration-associated proteins and mutations impair autophagy. This creates a potentially detrimental feedback loop whereby the accumulation of these disease-associated proteins impairs their autophagic clearance, facilitating their further accumulation and aggregation. Thus, understanding how autophagy interacts with aging, senescence, and neurodegenerative diseases in a temporal, cellular, and genetic context is important for the future clinical application of autophagy-modulating therapies in aging and neurodegeneration.

How close is autophagy-targeting therapy for Alzheimer's disease to clinical use? A summary of autophagy modulators in clinical studies

Alzheimer's disease (AD) is a neurodegenerative disorder clinically characterized by progressive decline of memory and cognitive functions, and it is the leading cause of dementia accounting for 60%-80% of dementia patients. A pathological hallmark of AD is the accumulation of aberrant protein/peptide aggregates such as extracellular amyloid plaques containing amyloid-beta peptides and intracellular neurofibrillary tangles composed of hyperphosphorylated tau. These aggregates result from the failure of the proteostasis network, which encompasses protein synthesis, folding, and degradation processes. Autophagy is an intracellular self-digesting system responsible for the degradation of protein aggregates and damaged organelles. Impaired autophagy is observed in most neurodegenerative disorders, indicating the link between autophagy dysfunction and these diseases. A massive accumulation of autophagic vacuoles in neurons in Alzheimer's brains evidences autophagy impairment in AD. Modulating autophagy has been proposed as a therapeutic strategy for AD because of its potential to clear aggregated proteins. However, autophagy modulation therapy for AD is not yet clinically available. This mini-review aims to summarize clinical studies testing potential autophagy modulators for AD and to evaluate their proximity to clinical use. We accessed clinicaltrials.gov provided by the United States National Institutes of Health to identify completed and ongoing clinical trials. Additionally, we discuss the limitations and challenges of these therapies.

Differences in gene expression between high and low tolerance rainbow trout (Oncorhynchus mykiss) to acute thermal stress

Understanding the mechanisms that underlie the adaptive response of ectotherms to rising temperatures is key to mitigate the effects of climate change. We assessed the molecular and physiological processes that differentiate between rainbow trout (Oncorhynchus mykiss) with high and low tolerance to acute thermal stress. To achieve our goal, we used a critical thermal maximum trial in two strains of rainbow trout to elicit loss of equilibrium responses to identify high and low tolerance fish. We then compared the hepatic transcriptome profiles of high and low tolerance fish relative to untreated controls common to both strains to uncover patterns of differential gene expression and to gain a broad perspective on the interacting gene pathways and functional processes involved. We observed some of the classic responses to increased temperature (e.g., induction of heat shock proteins) but these responses were not the defining factors that differentiated high and low tolerance fish. Instead, high tolerance fish appeared to suppress growth-related functions, enhance certain autophagy components, better regulate neurodegenerative processes, and enhance stress-related protein synthesis, specifically spliceosomal complex activities, mRNA regulation, and protein processing through post-translational processes, relative to low tolerance fish. In contrast, low tolerance fish had higher transcript diversity and demonstrated elevated developmental, cytoskeletal, and morphogenic, as well as lipid and carbohydrate metabolic processes, relative to high tolerance fish. Our results suggest that high tolerance fish engaged in processes that supported the prevention of further damage by enhancing repair pathways, whereas low tolerance fish were more focused on replacing damaged cells and their structures.

Cardioprotective effects of the electrolyte solution sterofundin and the possible underlying mechanisms

Background

Sterofundin (SF) is one of the most widely used electrolyte solutions in almost all areas of medicine, with particular importance in intensive care. It provides powerful correction of acid-base imbalances, ion fluctuations, and impaired energy metabolism, which are the three most important characteristics after myocardial infarction (MI). However, whether and how SF protects the heart from post-MI damage are largely unknown.

Methods and Results

Pretreating mice with SF before MI surgery reduced the number of reactive oxygen species (ROS)-positive and TUNEL-positive cells. As a result, the infarcted area cardiac fibrosis in the MI mice was reduced and cardiac performance in the MI mice improved. Moreover, RNA-seq analysis demonstrated that SF caused the gene expression profile of MI mice to shift toward that of sham mice, with a significant decrease in apoptosis-, ROS-, and inflammation-associated gene enrichment. RNA-seq analysis also demonstrated that SF induced the upregulation of autophagy-associated gene enrichment. Western blotting confirmed the RNA-seq analysis results, showing that SF induced the upregulation of an autophagic flux. When the autophagic flux was blocked with the autophagy inhibitor 3-methyladenine, the protective effect of SF was reduced.

Conclusion

SF protects the heart from post-MI damage, and one of the underlying mechanisms could be its autophagy modifications. This study is the first to reveal a previously unrecognized role of electrolyte solutions in post-MI intensive care.

Regulation of the NLRP3 inflammasome by autophagy and mitophagy

The NLRP3 inflammasome is a multiprotein complex that upon activation by the innate immune system drives a broad inflammatory response. The primary initial mediators of this response are pro-IL-1β and pro-IL-18, both of which are in an inactive form. Formation and activation of the NLRP3 inflammasome activates caspase-1, which cleaves pro-IL-1β and pro-IL-18 and triggers the formation of gasdermin D pores. Gasdermin D pores allow for the secretion of active IL-1β and IL-18 initiating the organism-wide inflammatory response. The NLRP3 inflammasome response can be beneficial to the host; however, if the NLRP3 inflammasome is inappropriately activated it can lead to significant pathology. While the primary components of the NLRP3 inflammasome are known, the precise details of assembly and activation are less well defined and conflicting. Here, we discuss several of the proposed pathways of activation of the NLRP3 inflammasome. We examine the role of subcellular localization and the reciprocal regulation of the NLRP3 inflammasome by autophagy. We focus on the roles of mitochondria and mitophagy in activating and regulating the NLRP3 inflammasome. Finally, we detail the impact of pathologic NLRP3 responses in the development and manifestations of pulmonary disease.

Role of Autophagy in Myocardial Remodeling After Myocardial Infarction

ABSTRACT

Autophagy is the process of reusing the body's senescent and damaged cell components, which can be regarded as the cellular circulatory system. There are 3 distinct forms of autophagy: macroautophagy, microautophagy, and chaperone-mediated autophagy. In the heart, autophagy is regulated mainly through mitophagy because of the metabolic changes of cardiomyocytes caused by ischemia and hypoxia. Myocardial remodeling is characterized by gradual heart enlargement, cardiac dysfunction, and extraordinary molecular changes. Cardiac remodeling after myocardial infarction is almost inevitable, which is the leading cause of heart failure. Autophagy has a protective effect on myocardial remodeling improvement. Autophagy can minimize cardiac remodeling by preventing misfolded protein accumulation and oxidative stress. This review summarizes the nestest molecular mechanisms of autophagy and myocardial remodeling, the protective effects, and the new target of autophagy medicine in cardiac remodeling. The future development and challenges of autophagy in heart disease are also summarized.