Macroautophagy in CNS health and disease

Pyroptosis, ferroptosis, and autophagy in spinal cord injury: regulatory mechanisms and therapeutic targets

Regulated cell death is a form of cell death that is actively controlled by biomolecules. Several studies have shown that regulated cell death plays a key role after spinal cord injury. Pyroptosis and ferroptosis are newly discovered types of regulated cell deaths that have been shown to exacerbate inflammation and lead to cell death in damaged spinal cords. Autophagy, a complex form of cell death that is interconnected with various regulated cell death mechanisms, has garnered significant attention in the study of spinal cord injury. This injury triggers not only cell death but also cellular survival responses. Multiple signaling pathways play pivotal roles in influencing the processes of both deterioration and repair in spinal cord injury by regulating pyroptosis, ferroptosis, and autophagy. Therefore, this review aims to comprehensively examine the mechanisms underlying regulated cell deaths, the signaling pathways that modulate these mechanisms, and the potential therapeutic targets for spinal cord injury. Our analysis suggests that targeting the common regulatory signaling pathways of different regulated cell deaths could be a promising strategy to promote cell survival and enhance the repair of spinal cord injury. Moreover, a holistic approach that incorporates multiple regulated cell deaths and their regulatory pathways presents a promising multi-target therapeutic strategy for the management of spinal cord injury.

Enhanced autophagic clearance of amyloid-β via histone deacetylase 6-mediated V-ATPase assembly and lysosomal acidification protects against Alzheimer's disease in vitro and in vivo

JOURNAL/nrgr/04.03/01300535-202509000-00025/figure1/v/2024-11-05T132919Z/r/image-tiff Recent studies have suggested that abnormal acidification of lysosomes induces autophagic accumulation of amyloid-β in neurons, which is a key step in senile plaque formation. Therefore, restoring normal lysosomal function and rebalancing lysosomal acidification in neurons in the brain may be a new treatment strategy for Alzheimer's disease. Microtubule acetylation/deacetylation plays a central role in lysosomal acidification. Here, we show that inhibiting the classic microtubule deacetylase histone deacetylase 6 with an histone deacetylase 6 shRNA or thehistone deacetylase 6 inhibitor valproic acid promoted lysosomal reacidification by modulating V-ATPase assembly in Alzheimer's disease. Furthermore, we found that treatment with valproic acid markedly enhanced autophagy, promoted clearance of amyloid-β aggregates, and ameliorated cognitive deficits in a mouse model of Alzheimer's disease. Our findings demonstrate a previously unknown neuroprotective mechanism in Alzheimer's disease, in which histone deacetylase 6 inhibition by valproic acid increases V-ATPase assembly and lysosomal acidification.

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.

Apigenin enhances Nrf2-induced chaperone-mediated autophagy and mitigates α-synuclein pathology: Implications for Parkinson's disease therapy

BACKGROUND

The aggregation of α-synuclein (SNCA) in dopaminergic neurons of the substantia nigra is a key factor in the pathogenesis of Parkinson's disease (PD). Despite years of drug discovery efforts targeting SNCA aggregation, no disease-modifying drugs have been approved to date. The failure of numerous clinical trials can be attributed, at least in part, to the difficulty in identifying potent compounds during preclinical investigations.

OBJECTIVE

Establish a screening approach based on molecular docking and autophagic flux detection to identify natural compounds from new perspectives of SNCA clearance and to explore its mechanism.

METHODS

Molecular docking technique combined with autophagic flux detection was performed for preliminary screening of flavonoids in PubChem and CHEBI databases. Western blotting was utilized to detect the levels of SNCA, chaperone-mediated autophagy (CMA)-associated proteins, apoptosis-related proteins, and neuroinflammatory biomarkers, alongside the assessment of phosphorylation status of proteins implicated in signaling cascades. JC-1 staining was used to measure the mitochondrial transmembrane potential (MMP). RNA-sequencing and Kyoto encyclopedia of genes and genomes/gene ontology (KEGG/GO) analysis were optimized to detect gene expression. PD mouse motor function was assessed using rotarod, pole, open field, footprint, and gait analyses. Immunofluorescence staining was employed to detect the expression of Nuclear factor erythroid 2-related factor 2 (Nrf2), dopaminergic neuronal deficits, microglia activation, and production of inflammatory factors. LysoTracker Red staining and pSIN-PAmCherry-KFERQ-NE plasmid were used to evaluate the lysosomal activity. pHrodo™ Green E.coli BioParticles™ were employed to measure phagocytosis activity.

RESULTS

By molecular docking and autophagic flux detection, we evaluated the efficacy of flavone derivatives and identified apigenin (AP) as a candidate that activates CMA to promote SNCA clearance and thereby inhibits SNCA-induced neurotoxicity. AP inhibited apoptosis by promoting SNCA degradation through Nrf2-mediated CMA activation. Moreover, AP could also inhibit apoptosis via the Nrf2/extracellular regulated protein kinases (ERK) feedback loop that operates independently of CMA activation. Additionally, AP enhanced the phagocytosis capabilities of BV2 cells and inhibited SNCA-induced neuroinflammation, both in vitro and in vivo.

CONCLUSIONS

AP activates CMA to promote the clearance of SNCA, thereby inhibiting SNCA-induced neurotoxicity. Nrf2 and its role in AP-mediated neuroprotection may provide new insights that target degradation pathways to counteract SNCA pathology in PD.

Autophagy Dysfunction and Neurodegeneration: Where Does It Go Wrong?

An infamous hallmark of neurodegenerative diseases is the accumulation of misfolded or unfolded proteins forming inclusions in the brain. The accumulation of these abnormal structures is a mysterious one, given that cells devote significant resources to integrate complementary pathways to ensure proteome integrity and proper protein folding. Aberrantly folded protein species are rapidly targeted for disposal by the ubiquitin-proteasome system (UPS), and even if this should fail, and the species accumulates, the cell can also rely on the lysosome-mediated degradation pathways of autophagy. Despite the many safeguards in place, failure to maintain protein homeostasis commonly occurs during, or preceding, the onset of disease. Over the last decade and a half, studies suggest that the failure of autophagy may explain the disruption in protein homeostasis observed in disease. In this review, we will examine how the highly complex cells of the brain can become vulnerable to failure of aggregate clearance at specific points during the processive pathway of autophagy, contributing to aggregate accumulation in brains with neurodegenerative disease.

Uncovering the Unique Roles of Cathepsins B and L in Purkinje Cells Using Nervous System-Specific CTSB and CTSL Double-Deficient Mice

Defects in the autophagy-lysosomal degradation pathway contribute to neurodegenerative diseases. Cathepsins B (CtsB) and L (CtsL) are major lysosomal cysteine proteases. Mice deficient in both CtsB and CtsL exhibit abnormalities not only in neural tissue but in other organs, such as heart and liver, with most dying at approximately 16 days of age. To investigate the roles of CtsB and CtsL in the nervous system, nervous system-specific CTSB and CTSL double-knockout mice (CtsB/L-NES) were generated. These mice displayed tail elevation, motor dysfunction, and hyperactivity. In adulthood, they developed cerebellar atrophy, with Purkinje cells in the cerebellar cortex showing selective loss of phospholipase C β4-positive and Zebrin II-negative Purkinje cells in a striped pattern. Ubiquitin-positive structures accumulated in the perikarya and axons of Purkinje cells, reflecting impaired autophagy-lysosomal degradation. Activation of astrocytes and microglia was observed in Purkinje cell loss regions. Electron microscopy revealed granular osmiophilic deposit-like structures in perikarya, autophagosome-like accumulations in axons, and a reduction in synaptic vesicles at active regions of swollen axon terminals in Purkinje cells. Additionally, neuronal loss was observed specifically in the ventral posterior lateral and ventral posterior medial nuclei of the thalamus. These findings demonstrate CtsB and CtsL are essential for survival of Purkinje cells in the cerebellum and neurons in the ventral posterior lateral and ventral posterior medial nuclei of the thalamus.

Stress dynamically modulates neuronal autophagy to gate depression onset

Chronic stress remodels brain homeostasis, in which persistent change leads to depressive disorders1. As a key modulator of brain homeostasis2, it remains elusive whether and how brain autophagy is engaged in stress dynamics. Here we discover that acute stress activates, whereas chronic stress suppresses, autophagy mainly in the lateral habenula (LHb). Systemic administration of distinct antidepressant drugs similarly restores autophagy function in the LHb, suggesting LHb autophagy as a common antidepressant target. Genetic ablation of LHb neuronal autophagy promotes stress susceptibility, whereas enhancing LHb autophagy exerts rapid antidepressant-like effects. LHb autophagy controls neuronal excitability, synaptic transmission and plasticity by means of on-demand degradation of glutamate receptors. Collectively, this study shows a causal role of LHb autophagy in maintaining emotional homeostasis against stress. Disrupted LHb autophagy is implicated in the maladaptation to chronic stress, and its reversal by autophagy enhancers provides a new antidepressant strategy.

Buyang Huanwu decoction facilitates the repair of red nucleus neurons subsequent to spinal cord injury in rats via autophagy

BACKGROUND

To explore the effects of Buyang Huanwu Decoction (BYHWD) on neurons in the red nucleus of rats with spinal cord injury (SCI) based on autophagy.

METHODS

120 Sprague-Dawley (SD) rats were randomly divided into 6 groups: Control Group, SCI Group, Bafilomycin A1 Group, Rapamycin Group, BYHWD low-dose group (BL Group, 6.25 g/kg), BYHWD high-dose group (BH Group, 25.00 g/kg), with 20 animals in each group. A rat rubrospinal tract (RST) transection model was established and treated for 28 days. The recovery of motor function of rats was observed through inclined plate test and spontaneous upright exploratory behavior test. Nissl's staining was used to observe the cell morphology of injured red nucleus neurons. Reverse Transcription PCR (RT-PCR) and immunofluorescence were used to detect the expression of ATG5 and Beclin1 mRNA. The Western blot method was used to observe the expression levels of Synaptophysin (SYP), Synaptosomal-associated Protein of 25 kDa (SNAP-25), Postsynaptic density protein 95 (PSD-95), ATG5, and Beclin1 proteins in red nucleus tissue.

RESULTS

Compared with the SCI group, both BL and BH groups significantly improved the forelimb motor function and improved the status of red nucleus neurons in SCI rats. BYHWD increased SYP, SNAP-25, PSD-95, and decreased the red core Beclin1 and ATG5.

CONCLUSIONS

BYHWD enhances synaptic regeneration and limb activity in red nucleus neurons of SCI rats by inhibiting autophagy.

Circular RNA Vav3 mediated ALV-J inhibition of autophagy by modulating the gga-miR-375/CIP2A axis and activating AKT

Avian leukosis virus subgroup J (ALV-J) is an immunosuppressive neoplastic virus, the growth retardation and growth performance of chickens after infection. Circular RNAs (circRNAs) play a crucial role in various types of cancer. In a previous study, we showed that circ-Vav3 was significantly elevated in the tumor livers of avian leukosis-infected chickens. Autophagy is an essential cellular process, and circRNAs have been confirmed to be key players in autophagy regulation. In this study, we demonstrated that overexpression of circ-Vav3 inhibited autophagy. Specifically, circ-Vav3 functions as a sponge for gga-miR-375, resulting in increased expression of CIP2A, which is a target gene of gga-miR-375. CIP2A, in turn, hinders the fusion of autophagosomes with lysosomes, leading to incomplete autophagic flux, consequently, the inhibition of autophagy. Further study confirmed that overexpression of gga-miR-375 inhibits CIP2A expression and promotes autophagy by downregulating p-AKT. Additionally, we treated cells with rapamycin to induce autophagy and then cotransfected them with circ-Vav3 and gga-miR-375. The results demonstrated that cotransfection of circ-Vav3 and gga-miR-375 inhibited cellular autophagy. Moreover, cells cotransfected with circ-Vav3 and gga-miR-375 exhibited further autophagy inhibition after ALV-J infection, suggesting that circ-Vav3 is involved in inhibiting autophagy caused by ALV-J infection through the regulation of gga-miR-375/CIP2A/AKT. In conclusion, our results demonstrated that circ-Vav3 inhibited autophagy through the gga-miR-375/CIP2A/AKT pathway and mediated the suppression of ALV-J-induced autophagy.

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.

WTAP suppresses STAT3 via m6A methylation to regulate autophagy and inflammation in central nervous system injury

Central nervous system (CNS) repair after injury is a challenging process limited by inflammation and neuronal apoptosis. This study identifies Wilms' tumor 1-associating protein (WTAP) as a pivotal regulator of neuronal protection and repair through m6A methylation of STAT3 mRNA. By employing spinal cord injury (SCI) as a representative model of CNS injury, transcriptomic analyses reveal WTAP as a key mediator of pathways related to neuronal autophagy and inflammation regulation. WTAP enhances neuronal autophagy by suppressing STAT3 expression and activity, which inhibits the NLRP3 inflammatory pathway. Functional studies demonstrate that WTAP knockdown exacerbates neuronal apoptosis, whereas overexpression improves cell viability, autophagy, and motor recovery. In vivo, WTAP promotes SCI repair via m6A-mediated suppression of STAT3 and regulation of the NLRP3 signaling pathway, highlighting its therapeutic potential for CNS injury repair.

Lipid metabolism, remodelling and intercellular transfer in the CNS

Lipid metabolism encompasses the catabolism and anabolism of lipids, and is fundamental for the maintenance of cellular homeostasis, particularly within the lipid-rich CNS. Increasing evidence further underscores the importance of lipid remodelling and transfer within and between glial cells and neurons as key orchestrators of CNS lipid homeostasis. In this Review, we summarize and discuss the complex landscape of processes involved in lipid metabolism, remodelling and intercellular transfer in the CNS. Highlighted are key pathways, including those mediating lipid (and lipid droplet) biogenesis and breakdown, lipid oxidation and phospholipid metabolism, as well as cell-cell lipid transfer mediated via lipoproteins, extracellular vesicles and tunnelling nanotubes. We further explore how the dysregulation of these pathways contributes to the onset and progression of neurodegenerative diseases, and examine the homeostatic and pathogenic impacts of environment, diet and lifestyle on CNS lipid metabolism.

Hallmarks of aging in age-related macular degeneration and age-related neurological disorders: novel insights into common mechanisms and clinical relevance

Age-related macular degeneration (AMD) and age-related neurological diseases (ANDs), such as Alzheimer's and Parkinson's Diseases, are increasingly prevalent conditions that significantly contribute to global morbidity, disability, and mortality. The retina, as an accessible part of the central nervous system (CNS), provides a unique window to study brain aging and neurodegeneration. By examining the associations between AMD and ANDs, this review aims to highlight novel insights into fundamental mechanisms of aging and their role in neurodegenerative disease progression. This review integrates knowledge from the emerging field of aging research, which identifies common denominators of biological aging, specifically loss of proteostasis, impaired macroautophagy, mitochondrial dysfunction, and inflammation. Finally, we emphasize the clinical relevance of these pathways and the potential for cross-disease therapies that target common aging hallmarks. Identifying these shared pathways could open avenues to develop therapeutic strategies targeting mechanisms common to multiple degenerative diseases, potentially attenuating disease progression and promoting the healthspan.

Neurofilament accumulation disrupts autophagy in giant axonal neuropathy

Neurofilament accumulation is associated with many neurodegenerative diseases, but it is the primary pathology in giant axonal neuropathy (GAN). This childhood-onset autosomal recessive disease is caused by loss-of-function mutations in gigaxonin, the E3 adaptor protein that enables neurofilament degradation. Using a combination of genetic and RNA interference approaches, we found that dorsal root ganglia from mice lacking gigaxonin have impaired autophagy and lysosomal degradation through 2 mechanisms. First, neurofilament accumulations interfere with the distribution of autophagic organelles, impairing their maturation and fusion with lysosomes. Second, the accumulations attract the chaperone 14-3-3, which is responsible for the proper localization of the key autophagy regulator transcription factor EB (TFEB). We propose that this dual disruption of autophagy contributes to the pathogenesis of other neurodegenerative diseases involving neurofilament accumulations.

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.

Molecular mechanism on autophagy associated cardiovascular dysfunction in Drosophila melanogaster

As a highly conserved cellular process, autophagy has been the focus of extensive research due to its critical role in maintaining cellular homeostasis and its implications in cardiovascular pathogenesis. The decline in muscular function, along with the neuronal system, and increased sensitivity to stress have been recognized in multiple animal models. Autophagic defects in cardiovascular architecture and cellular dysfunction have been linked to both physiological and pathological conditions of the heart in mammals and Drosophila. In this review, we systematically analyze the autophagy-associated pathways in the hearts of fruit flies and aim to provide a comprehensive understanding for developing potential treatments for patients and effective strategies for agricultural applications. This analysis elucidates the molecular mechanisms of autophagy in cardiovascular function under both physiological and pathological conditions in Drosophila, offering significant insights into the development of cardiovascular diseases. The loss of key autophagy-associated proteins, including the transmembrane protein Atg9 and its partners Atg2 or Atg18, along with DmSestrin, leads to cardiac hypertrophy and structural abnormalities in Drosophila, resembling the age-dependent deterioration of cardiac function. Members of the autophagy-related (Atg) gene family, cellular or nuclear skeletal lamins, and the mechanistic or mammalian target of rapamycin (mTOR) signaling pathways are critically influential in heart function in Drosophila, with autophagy activation shown to suppress cardiac laminopathy. The mTORC1/C2 complexes, along with axis of Atg2-AMPK/Sirt1/PGC-1α pathway, are essential in the hearts of both mammals and fruit flies, governing cardiac development, growth, maturation, and the maintenance of cardiac homeostasis. The beneficial effects of several interventions that enhance cardiac function, including exercise and cold stress, can influence autophagy-dependent TOR activity of the serine/threonine protein kinase signaling in both mammals and Drosophila. Exercise has been shown to increase autophagy when it is deficient and to inhibit it when it is excessive, highlighting the dual role of autophagy in cardiac health. This review evaluates the functional significance of autophagy in the heart, particularly in the context of Drosophila, in relation to mTORC-associated autophagy and the axis of Atg2-AMPK/Sirt1/PGC-1α pathways. It systematically contrasts the molecular mechanisms underlying autophagy-related cardiovascular physiological and pathological conditions in both fruit flies and mammals. The evolutionary conservation of autophagy underscores the value of Drosophila as a model for understanding broader mechanisms of autophagy across species. This study not only deepens our understanding of autophagy's role in cardiovascular function but also provides a theoretical foundation for the potential application of autophagy in agricultural pest control.

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.

NEAT1-mediated regulation of proteostasis and mRNA localization impacts autophagy dysregulation in Rett syndrome

Rett syndrome (RTT) is a severe neurodevelopmental disorder primarily caused by loss-of-function mutations in the MECP2 gene, resulting in diverse cellular dysfunctions. Here, we investigated the role of the long noncoding RNA (lncRNA) NEAT1 in the context of MeCP2 deficiency using human neural cells and RTT patient samples. Through single-cell RNA sequencing and molecular analyses, we found that NEAT1 is markedly downregulated in MECP2 knockout (KO) cells at various stages of neural differentiation. NEAT1 downregulation correlated with aberrant activation of the mTOR pathway, abnormal protein metabolism, and dysregulated autophagy, contributing to the accumulation of protein aggregates and impaired mitochondrial function. Reactivation of NEAT1 in MECP2-KO cells rescued these phenotypes, indicating its critical role downstream of MECP2. Furthermore, direct RNA-RNA interaction was revealed as the key process for NEAT1 influence on autophagy genes, leading to altered subcellular localization of specific autophagy-related messenger RNAs and impaired biogenesis of autophagic complexes. Importantly, NEAT1 restoration rescued the morphological defects observed in MECP2-KO neurons, highlighting its crucial role in neuronal maturation. Overall, our findings elucidate lncRNA NEAT1 as a key mediator of MeCP2 function, regulating essential pathways involved in protein metabolism, autophagy, and neuronal morphology.

Hallmarks of aging: A user's guide for comparative biologists

Since the first description of a set of characteristics of aging as so-called hallmarks or pillars in 2013/2014, these characteristics have served as guideposts for the research in aging biology. They have been examined in a range of contexts, across tissues, in response to disease conditions or environmental factors, and served as a benchmark for various anti-aging interventions. While the hallmarks of aging were intended to capture generalizable characteristics of aging, they are derived mostly from studies of rodents and humans. Comparative studies of aging including species from across the animal tree of life have great promise to reveal new insights into the mechanistic foundations of aging, as there is a great diversity in lifespan and age-associated physiological changes. However, it is unclear how well the defined hallmarks of aging apply across diverse species. Here, we review each of the twelve hallmarks of aging defined by Lopez-Otin in 2023 with respect to the availability of data from diverse species. We evaluate the current methods used to assess these hallmarks for their potential to be adapted for comparative studies. Not unexpectedly, we find that the data supporting the described hallmarks of aging are restricted mostly to humans and a few model systems and that no data are available for many animal clades. Similarly, not all hallmarks can be easily assessed in diverse species. However, for at least half of the hallmarks, there are methods available today that can be employed to fill this gap in knowledge, suggesting that these studies can be prioritized while methods are developed for comparative study of the remaining hallmarks.

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.

Intermittent Fasting Improves Sevoflurane-Induced Cognitive Dysfunction in Rats Through SIRT1-Mediated Autophagy

Perioperative neurocognitive disorders (PND) is a common complication affecting the central nervous system, commonly induced by anesthesia and surgical procedures. PND has garnered considerable attention in recent years, not only due to its high morbidity but also its negative impact on patient prognosis, such as increased rates of dementia and mortality. Sevoflurane, a common volatile anesthetic in clinical practice, is increasingly linked to being a potential risk factor for PND with prolonged inhalation, yet effective prevention and treatment methods remain elusive. Autophagy, a crucial regulatory process for maintaining organism function, has been shown to play a key role in sevoflurane-induced cognitive dysfunction. In recent years, intermittent fasting (IF), a unique dietary pattern, has gained significant recognition. IF has been shown in multiple studies to offer neuroprotective advantages in different central nervous system conditions. disorders. This study aims to explore the potential neuroprotective effects of intermittent fasting preconditioning through the autophagic pathway in sevoflurane-induced cognitive impairment in rats and its underlying mechanisms.

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.

Atg5-Mediated Lipophagy Induces Ferroptosis in Corneal Epithelial Cells in Dry Eye Disease

Purpose

Ferroptosis occurred in corneal epithelial cells has been implicated in the inflammation in dry eye disease (DED). Given the proposed link between ferroptosis and autophagy, this study aims to investigate the role of autophagy in driving ferroptosis in corneal epithelial cell and enrich the pathogenesis underlying DED.

Methods

DED models were established in C57BL/6 mice via scopolamine injection and in human corneal epithelial cell line (HCEC) using hyperosmotic medium. Lipidomic and transcriptomic analysis were conducted to assess lipid metabolism and regulatory pathways. Atg5 expression was manipulated in vivo using cholesterol-modified small interfering RNA. Lipid droplets (LDs) and lysosomes were labeled with BODIPY 493/503 and Lysotracker Red DND-99, respectively. Western blot, immunofluorescence (IF) staining, co-immunoprecipitation (CO-IP), transmission electron microscopy and microplate reader were used to explore protein expressions and interactions, cellular structures, and free fatty acid (FFA) content.

Results

Our results revealed that autophagy was activated in DED, as evidenced by lipidomic and transcriptomic analyses. Enhanced lipophagy was observed in HCECs exposed to hyperosmolarity, manifested by lysosome-LD co-localization and autophagic vacuoles containing LDs. Upregulation of Atg5 promoted lipophagy, leading to elevated cellular FFA levels, lipid peroxidation, and expression of ferroptosis markers. Interaction between Atg5 and perilipin3 was confirmed through CO-IP and IF. In the DED mouse model, Atg5 inhibition effectively ameliorated corneal damage, suppressed ferroptosis and ocular surface inflammation.

Conclusions

Our findings highlight the pivotal role of Atg5-mediated lipophagy in driving ferroptosis in corneal epithelial cells in DED, proposing Atg5 as a promising therapeutic target for mitigating ferroptosis-induced cell damage and inflammation in DED.

A new perspective on targeting pulmonary arterial hypertension: Programmed cell death pathways (Autophagy, Pyroptosis, Ferroptosis)

Pulmonary arterial hypertension (PAH) is a severe cardiovascular disease characterized by elevated pulmonary vascular resistance, progressive increases in pulmonary artery pressures, ultimately leading to right-sided heart failure, and potentially mortality. Pulmonary vascular remodeling is pivotal in PAH onset and progression. While targeted drug therapies have notably ameliorated PAH prognosis, current medications primarily focus on vascular vasodilation, with limited ability to reverse pulmonary vascular remodeling fundamentally, resulting in suboptimal patient prognoses. Cellular death in pulmonary vasculature, once thought to be confined to apoptosis and necrosis, has evolved with the identification of pyroptosis, autophagy, and ferroptosis, revealing their association with vascular injury in PAH. These novel forms of regulated cellular death impact reactive oxygen species (ROS) generation, calcium stress, and inflammatory cascades, leading to pulmonary vascular cell loss, exacerbating vascular injury, and mediating adverse remodeling, inflammation, immune anomalies, and current emerging mechanisms (such as endothelial-mesenchymal transition, abnormal energy metabolism, and epigenetic regulation) in the pathogenesis of PAH. This review comprehensively delineates the roles of autophagy, pyroptosis, and ferroptosis in PAH, elucidating recent advances in their involvement and regulation of vascular injury. It juxtaposes their distinct functions in PAH and discusses the interplay of these programmed cell deaths in pulmonary vascular injury, highlighting the benefits of combined targeted therapies in mitigating pulmonary arterial hypertension-induced vascular injury, providing novel insights into targeted treatments for pulmonary arterial hypertension.

Occupational agents-mediated asthma: From the perspective of autophagy

Occupational asthma (OA) is a common occupational pulmonary disease that is frequently underdiagnosed and underreported. The complexity of diagnosing and treating OA creates a significant social and economic burden, making it an important public health issue. In addition to avoiding allergens, patients with OA require pharmacotherapy; however, new therapeutic targets and strategies need further investigation. Autophagy may be a promising intervention target, but there is a lack of relevant studies summarizing the role of autophagy in OA. In this review consolidates the current understanding of OA, detailing principal and novel agents responsible for its onset. Additionally, we summarize the mechanisms of autophagy in HMW and LMW agents induced OA, revealing that occupational allergens can induce autophagy disorders in lung epithelial cells, smooth muscle cells, and dendritic cells, ultimately leading to OA through involving inflammatory responses, oxidative stress, and cell death. Finally, we discuss the prospects of targeting autophagy as an effective strategy for managing OA and even steroid-resistant asthma, encompassing autophagy interventions focused on organoids, organ-on-a-chip systems, nanomaterials vehicle, and nanobubbles; developing combined exposure models, and the role of non-classical autophagy in occupational asthma. In briefly, this review summarizes the role of autophagy in occupational asthma, offers a theoretical foundation for OA interventions based on autophagy, and identifies directions and challenges for future research.

Inflammation, mitochondrial and lysosomal dysfunction as key players in rheumatoid arthritis?

Rheumatoid arthritis (RA) is an inflammatory joint disease characterized by persistent synovitis and inflammation. The exact mechanism of mitochondrial function in the presence of inflammation and dysregulation of autophagic processes in the pathogenesis of RA is still unclear. The aim of our study is to determine mitochondrial function, gene and protein levels of biomolecules related to inflammation (YKL-40) and autophagy (LAMPs) and to search a connection between them in the RA context. Twenty newly diagnosed RA patients and ten healthy individuals were included in the study. Disease severity was assessed by ultrasonography. Conventional clinico-laboratory parameters, immunological markers and protein levels of LAMPs and YKL-40 were examined in plasma. Gene expression analysis for the quantitative measurement of LAMPs and YKL-40 were conducted in white blood cells (WBC). A real-time metabolic analysis was performed to assess mitochondrial function and cell metabolism in peripheral blood mononuclear cells (PBMCs). Increase in spare respiratory capacity in PBMCs of RA patients was detected. Decreased LAMPs plasma protein levels and increased protein levels of YKL-40 in RA patients compared to healthy individuals were measured. No significant differences were found in gene expressions. Correlations between mitochondrial, ultrasonographic and protein levels of the biomarkers related with inflammation and autophagy were established. New data on mitochondrial dysfunction in RA patients and links to inflammation and mitophagy are reported. The relationship between dysregulation of mitophagy and joint diseases deserves to be thoroughly investigated as it would be a promising therapeutic approach.

Lactate-mediated lactylation in human health and diseases: Progress and remaining challenges

BACKGROUND

Lactate was once considered as metabolic waste for a long time. In 2019, Professor Zhao Yingming's team from the University of Chicago found that lactate could also be used as a substrate to induce histone lactylation and regulate gene expression. Since then, researchers have discovered that lactate-mediated lactylation play important regulatory roles in various physiological and pathological processes.

AIM OF REVIEW

In this review, we aim to discuss the roles and mechanisms of lactylation in human health and diseases, as well as the effects of lactylation on proteins and metabolic modulators targeting lactylation.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this work, we emphasize the crucial regulatory roles of lactylation in the development of numerous physiological and pathological processes. Of relevance, we discuss the current issues and challenges pertaining to lactylation. This review provides directions and a theoretical basis for future research and clinical translation of lactylation.

Adult-onset deactivation of autophagy leads to loss of synapse homeostasis and cognitive impairment, with implications for alzheimer disease

A growing number of studies link dysfunction of macroautophagy/autophagy to the pathogenesis of diseases such as Alzheimer disease (AD). Given the global importance of autophagy for homeostasis, how its dysfunction can lead to specific neurological changes is puzzling. To examine this further, we compared the global deactivation of autophagy in the adult mouse using the atg7iKO with the impact of AD-associated pathogenic changes in autophagic processing of synaptic proteins. Isolated forebrain synaptosomes, rather than total homogenates, from atg7iKO mice demonstrated accumulation of synaptic proteins, suggesting that the synapse might be a vulnerable site for protein homeostasis disruption. Moreover, the deactivation of autophagy resulted in impaired cognitive performance over time, whereas gross locomotor skills remained intact. Despite deactivation of autophagy for 6.5 weeks, changes in cognition were in the absence of cell death or synapse loss. In the symptomatic APP PSEN1 double-transgenic mouse model of AD, we found that the impairment in autophagosome maturation coupled with diminished presence of discrete synaptic proteins in autophagosomes isolated from these mice, leading to the accumulation of one of these proteins in the detergent insoluble protein fraction. This protein, SLC17A7/Vglut, also accumulated in atg7iKO mouse synaptosomes. Taken together, we conclude that synaptic autophagy plays a role in maintaining protein homeostasis, and that while decreasing autophagy interrupts normal cognitive function, the preservation of locomotion suggests that not all circuits are affected similarly. Our data suggest that the disruption of autophagic activity in AD may have relevance for the cognitive impairment in this adult-onset neurodegenerative disease. Abbreviations: 2dRAWM: 2-day radial arm water maze; AD: Alzheimer disease; Aβ: amyloid-beta; AIF1/Iba1: allograft inflammatory factor 1; APP: amyloid beta precursor protein; ATG7: autophagy related 7; AV: autophagic vacuole; CCV: cargo capture value; Ctrl: control; DLG4/PSD-95: discs large MAGUK scaffold protein 4; GFAP: glial fibrillary acidic protein; GRIN2B/NMDAR2b: glutamate ionotropic receptor NMDA type subunit 2B; LTD: long-term depression; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; m/o: months-old; PNS: post-nuclear supernatant; PSEN1/PS1: presenilin 1; SHB: sucrose homogenization buffer; SLC32A1/Vgat: solute carrier family 32 member 1; SLC17A7/Vglut1: solute carrier family 17 member 7; SNAP25: synaptosome associated protein 25; SQSTM1/p62: sequestosome 1; SYN1: synapsin I; SYP: synaptophysin ; SYT1: synaptotagmin 1; Tam: tamoxifen; VAMP2: vesicle associated membrane protein 2; VCL: vinculin; wks: weeks.

Targeting selective autophagy in CNS disorders by small-molecule compounds

Autophagy functions as the primary cellular mechanism for clearing unwanted intracellular contents. Emerging evidence suggests that the selective elimination of intracellular organelles through autophagy, compared to the increased bulk autophagic flux, is crucial for the pathological progression of central nervous system (CNS) disorders. Notably, autophagic removal of mitochondria, known as mitophagy, is well-understood in an unhealthy brain. Accumulated data indicate that selective autophagy of other substrates, including protein aggregates, liposomes, and endoplasmic reticulum, plays distinctive roles in various pathological stages. Despite variations in substrates, the molecular mechanisms governing selective autophagy can be broadly categorized into two types: ubiquitin-dependent and -independent pathways, both of which can be subjected to regulation by small-molecule compounds. Notably, natural products provide the remarkable possibility for future structural optimization to regulate the highly selective autophagic clearance of diverse substrates. In this context, we emphasize the selectivity of autophagy in regulating CNS disorders and provide an overview of chemical compounds capable of modulating selective autophagy in these disorders, along with the underlying mechanisms. Further exploration of the functions of these compounds will in turn advance our understanding of autophagic contributions to brain disorders and illuminate precise therapeutic strategies for these diseases.

Heterophyllin B enhances transcription factor EB-mediated autophagy and alleviates pyroptosis and oxidative stress after spinal cord injury

Traumatic spinal cord injury (SCI) has devastating physical, psychosocial, and vocational implications for patients and caregivers. Heterophyllin B (HB) is a brain-permeable cyclopeptide from Pseudostellaria heterophylla that promotes axonal regeneration and neuroinflammation. However, the efficacy of HB in improving functional recovery following SCI and the underlying mechanisms remain unclear. This study utilized a murine model for SCI assessment to evaluate the therapeutic effects of HB. following HB intervention, functional recovery post-SCI, was assessed through the Basso Mouse Scale, gait analysis, and the detection of motor-evoked potentials (MEPs). RNA sequencing was used to study the roles of pyroptosis, oxidative stress, and autophagy in HB's impact on SCI. Techniques such as Western blot, immunofluorescence, and enzyme-linked immunosorbent assay were used to evaluate pyroptosis, oxidative stress, and autophagy markers. Associated virus vectors were used to suppress transcription factor EB (TFEB), an autophagy regulator, in a living organism. HB promoted autophagy by enhancing TFEB nuclear translocation. In contrast, it inhibited pyroptosis and oxidative stress. Based on using the adenosine monophosphate-activated protein kinase (AMPK) inhibitor Compound C, the AMPK-TRPML1-calcineurin pathway was involved in HB's regulation of TFEB. In summary, this study demonstrated that HB facilitated functional recuperation by stimulating TFEB-driven autophagy while simultaneously suppressing pyroptosis and oxidative stress after SCI, indicating its potential for clinical application.

Autophagic degradation of DHCR7 activates AKT3 and promotes sevoflurane-induced hippocampal neuroinflammation in neonatal mice

Repeated sevoflurane exposure in neonatal mice triggers neuroinflammation with detrimental effects on cognitive function. Yet, the mechanism of the sevoflurane-induced cytokine response is largely unknown. In this study, we reveal that 3-MA, an autophagy inhibitor, attenuated the sevoflurane-induced neuroinflammation and cognitive dysfunction, including the decreased freezing time and fewer platform crossings, in the neonate mice. 3-Methyladenine (3-MA) suppressed sevoflurane-induced expression of interleukin-6 and tumor necrosis factor-alpha in vitro. Moreover, sevoflurane activates IRF3, facilitating cytokine transcription in an AKT3-dependent manner. Mechanistically, sevoflurane-induced autophagic degradation of dehydrocholesterol-reductase-7 (DHCR7) resulted in accumulations of its substrate 7-dehydrocholesterol (7-DHC), mimicking the effect of sevoflurane on AKT3 activation and IRF3-driven cytokine expression. 3-MA significantly reversed sevoflurane-induced DHCR7 degradation, AKT phosphorylation, IRF3 activation, and the accumulation of 7-DHC in the hippocampal CA1 region. These findings pave the way for additional investigations aimed at developing novel strategies to mitigate postoperative cognitive impairment in pediatric patients.

Role of FMRP in AKT/mTOR pathway-mediated hippocampal autophagy in fragile X syndrome

Fragile X syndrome (FXS) is caused by epigenetic silencing of the Fmr1 gene, leading to the deletion of the coding protein FMRP. FXS induces abnormal hippocampal autophagy and mTOR overactivation. However, it remains unclear whether FMRP regulates hippocampal autophagy through the AKT/mTOR pathway, which influences the neural behavior of FXS. Our study revealed that FMRP deficiency increased the protein levels of p-ULK-1 and p62 and decreased LC3II/LC3I level in Fmr1 knockout (KO) mice. The mouse hippocampal neuronal cell line HT22 with knockdown of Fmr1 by lentivirus showed that the protein levels of p-ULK-1 and p62 were increased, whereas LC3II/LC3I was unchanged. Further observations revealed that FMRP deficiency obstructed autophagic flow in HT22 cells. Therefore, FMRP deficiency inhibited autophagy in the mouse hippocampus and HT22 cells. Moreover, FMRP deficiency increased reactive oxygen species (ROS) level, decreased the co-localization between the mitochondrial outer membrane proteins TOM20 and LC3 in HT22 cells, and caused a decrease in the mitochondrial autophagy protein PINK1 in HT22 cells and Fmr1 KO mice, indicating that FMRP deficiency caused mitochondrial autophagy disorder in HT22 cells and Fmr1 KO mice. To explore the mechanism by which FMRP deficiency inhibits autophagy, we examined the AKT/mTOR signaling pathway in the hippocampus of Fmr1 KO mice, found that FMRP deficiency caused overactivation of the AKT/mTOR pathway. Rapamycin-mediated mTOR inhibition activated and enhanced mitochondrial autophagy. Finally, we examined whether rapamycin affected the neurobehavior of Fmr1 KO mice. The Fmr1 KO mice exhibited stereotypical behavior, impaired social ability, and learning and memory impairment, while rapamycin treatment improved behavioral disorders in Fmr1 KO mice. Thus, our study revealed the molecular mechanism by which FMRP regulates autophagy function, clarifying the role of hippocampal neuron mitochondrial autophagy in the pathogenesis of FXS, and providing novel insights into potential therapeutic targets of FXS.

Importance of Autophagy Regulation in Glioblastoma with Temozolomide Resistance

Glioblastoma (GBM) is the most aggressive and common malignant and CNS tumor, accounting for 47.7% of total cases. Glioblastoma has an incidence rate of 3.21 cases per 100,000 people. The regulation of autophagy, a conserved cellular process involved in the degradation and recycling of cellular components, has been found to play an important role in GBM pathogenesis and response to therapy. Autophagy plays a dual role in promoting tumor survival and apoptosis, and here we discuss the complex interplay between autophagy and GBM. We summarize the mechanisms underlying autophagy dysregulation in GBM, including PI3K/AKT/mTOR signaling, which is most active in brain tumors, and EGFR and mutant EGFRvIII. We also review potential therapeutic strategies that target autophagy for the treatment of GBM, such as autophagy inhibitors used in combination with the standard of care, TMZ. We discuss our current understanding of how autophagy is involved in TMZ resistance and its role in glioblastoma development and survival.

Autophagy in Disease Onset and Progression

Autophagy is a biological phenomenon whereby components of cells can self-degrade using autophagosomes. During this process, cells can clear dysfunctional organelles or unwanted elements. Autophagy can recycle unnecessary biomolecules into new components or sometimes, even destroy the cells themselves. This cellular process was first observed in 1962 by Keith R. Porter et al. Since then, autophagy has been studied for over 60 years, and much has been learned on the topic. Nevertheless, the process is still not fully understood. It has been proven, for example, that autophagy can be a positive force for maintaining good health by removing older or damaged cells. By contrast, autophagy is also involved in the onset and progression of various conditions caused by pathogenic infections. These diseases generally involve several important organs in the human body, including the liver, kidney, heart, and central nervous system. The regulation of the defects of autophagy defects may potentially be used to treat some diseases. This review comprehensively discusses recent research frontiers and topics of interest regarding autophagy-related diseases.

Interactions Between Extracellular Vesicles and Autophagy in Neuroimmune Disorders

Neuroimmune disorders, such as multiple sclerosis, neuromyelitis optica spectrum disorder, myasthenia gravis, and Guillain-Barré syndrome, are characterized by the dysfunction of both the immune system and the nervous system. Increasing evidence suggests that extracellular vesicles and autophagy are closely associated with the pathogenesis of these disorders. In this review, we summarize the current understanding of the interactions between extracellular vesicles and autophagy in neuroimmune disorders and discuss their potential diagnostic and therapeutic applications. Here we highlight the need for further research to fully understand the mechanisms underlying these disorders, and to develop new diagnostic and therapeutic strategies.

Destabilization of fear memory by Rac1-driven engram-microglia communication in hippocampus

Rac1 is a key regulator of the cytoskeleton and neuronal plasticity, and is known to play a critical role in psychological and cognitive brain disorders. To elucidate the engram specific Rac1 signaling in fear memory, a doxycycline (Dox)-dependent robust activity marking (RAM) system was used to label dorsal dentate gyrus (DG) engram cells in mice during contextual fear conditioning. Rac1 mRNA and protein levels in DG engram cells were peaked at 24 h (day 1) after fear conditioning and were more abundant in the fear engram cells than in the non-engram cells. Optogenetic activation of Rac1 in a temporal manner in DG engram cells before memory retrieval decreased the freezing level in the fear context. Optogenetic activation of Rac1 increased autophagy protein 7 (ATG7) expression in the DG engram cells and activated DG microglia. Microglia-specific transcriptomics and fluorescence in situ hybridization revealed that overexpression of ATG7 in the fear engram cells upregulated the mRNA of Toll-like receptor TLR2/4 in DG microglia. Knockdown of microglial TLR2/4 rescued fear memory destabilization induced by ATG7 overexpression or Rac1 activation in DG engram cells. These results indicate that Rac1-driven communications between engram cells and microglia contributes to contextual fear memory destabilization, and is mediated by ATG7 and TLR2/4, and suggest a novel mechanistic framework for the cytoskeletal regulator in fear memory interference.

Research progresses on mitochondrial-targeted biomaterials for bone defect repair

In recent years, the regulation of the cell microenvironment has opened up new avenues for bone defect repair. Researchers have developed novel biomaterials to influence the behavior of osteoblasts and immune cells by regulating the microenvironment, aiming to achieve efficient bone repair. Mitochondria, as crucial organelles involved in energy conversion, biosynthesis and signal transduction, play a vital role in maintaining bone integrity. Dysfunction of mitochondria can have detrimental effects on the transformation of the immune microenvironment and the differentiation of stem cells, thereby hindering bone tissue regeneration. Consequently, targeted therapy strategies focusing on mitochondria have emerged. This approach offers a wide range of applications and reliable therapeutic effects, thereby providing a new treatment option for complex and refractory bone defect diseases. In recent studies, more biomaterials have been used to restore mitochondrial function and promote positive cell differentiation. The main directions are mitochondrial energy metabolism, mitochondrial biogenesis and mitochondrial quality control. In this review, we investigated the biomaterials used for mitochondria-targeted treatment of bone defect repair in recent years from the perspective of progress and strategies. We also summarized the micro-molecular mechanisms affected by them. Through discussions on energy metabolism, oxidative stress regulation and autophagy regulation, we emphasized the opportunities and challenges faced by mitochondria-targeted biomaterials, providing vital clues for developing a new generation of bone repair materials.

EHHADH deficiency regulates pexophagy and accelerates tubulointerstitial injury in diabetic kidney disease

Peroxisomal L-bifunctional enzyme (EHHADH) plays a role in the classic peroxisomal fatty acid β-oxidation pathway; however, the relationship between EHHADH expression and diabetic kidney disease has not been well understood. Here, we found that endogenous EHHADH levels were strongly correlated with the progression and severity of diabetic nephropathy in T2D patients. EHHADH knockout mice exhibited worsened renal tubular injury in diabetic mice. Furthermore, EHHADH is a modulator of pexophagy. In renal tubular epithelial cells (RTECs) in vitro, the knockdown of EHHADH induced a dramatic loss of peroxisomes. The loss of peroxisomes in EHHADH-deficient RTECs was restored by either an autophagic inhibitor 3-methyladenine or bafilomycin A1 both in vitro and in vivo. NBR1 was required for pexophagy in EHHADH-knockdown cells, where the level of reactive oxygen species (ROS) was increased, while inhibition of ROS blocked pexophagy. In summary, our findings revealed EHHADH deficiency accelerated renal injury in DKD as a modulator of pexophagy.

Nanodrugs based on co-delivery strategies to combat cisplatin resistance

Cisplatin (CDDP), as a broad-spectrum anticancer drug, is able to bind to DNA and inhibit cell division. Despite the widespread use of cisplatin since its discovery, cisplatin resistance developed during prolonged chemotherapy, similar to other small molecule chemotherapeutic agents, severely limits its clinical application. Cisplatin resistance in cancer cells is mainly caused by three reasons: DNA repair, decreased cisplatin uptake/increased efflux, and cisplatin inactivation. In earlier combination therapies, the emergence of multidrug resistance (MDR) in cancer cells prevented the achievement of the desired therapeutic effect even with the accurate combination of two chemotherapeutic drugs. Therefore, combination therapy using nanocarriers for co-delivery of drugs is considered to be ideal for alleviating cisplatin resistance and reducing cisplatin-related toxicity in cancer cells. This article provides an overview of the design of cisplatin nano-drugs used to combat cancer cell resistance, elucidates the mechanisms of action of cisplatin and the pathways through which cancer cells develop resistance, and finally discusses the design of drugs and related carriers that can synergistically reduce cancer resistance when combined with cisplatin.

Neuroprotective effects of chaperone-mediated autophagy in neurodegenerative diseases

ABSTRACT

Chaperone-mediated autophagy is one of three types of autophagy and is characterized by the selective degradation of proteins. Chaperone-mediated autophagy contributes to energy balance and helps maintain cellular homeostasis, while providing nutrients and support for cell survival. Chaperone-mediated autophagy activity can be detected in almost all cells, including neurons. Owing to the extreme sensitivity of neurons to their environmental changes, maintaining neuronal homeostasis is critical for neuronal growth and survival. Chaperone-mediated autophagy dysfunction is closely related to central nervous system diseases. It has been shown that neuronal damage and cell death are accompanied by chaperone-mediated autophagy dysfunction. Under certain conditions, regulation of chaperone-mediated autophagy activity attenuates neurotoxicity. In this paper, we review the changes in chaperone-mediated autophagy in neurodegenerative diseases, brain injury, glioma, and autoimmune diseases. We also summarize the most recent research progress on chaperone-mediated autophagy regulation and discuss the potential of chaperone-mediated autophagy as a therapeutic target for central nervous system diseases.

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

BACKGROUND AND PURPOSE

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

EXPERIMENTAL APPROACH

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

KEY RESULTS

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

CONCLUSION AND IMPLICATIONS

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

Autophagy in Neuroinflammation: A Focus on Epigenetic Regulation

Neuroinflammation, characterized by the secretion of abundant inflammatory mediators, pro-inflammatory polarization of microglia, and the recruitment of infiltrating myeloid cells to foci of inflammation, drives or exacerbates the pathological processes of central nervous system disorders, especially in neurodegenerative diseases. Autophagy plays an essential role in neuroinflammatory processes, and the underlaying physiological mechanisms are closely correlated with neuroinflammation-related signals. Inhibition of mTOR and activation of AMPK and FOXO1 enhance autophagy and thereby suppress NLRP3 inflammasome activity and apoptosis, leading to the relief of neuroinflammatory response. And autophagy mitigates neuroinflammation mainly manifested by promoting the polarization of microglia from a pro-inflammatory to an anti-inflammatory state, reducing the production of pro-inflammatory mediators, and up-regulating the levels of anti-inflammatory factors. Notably, epigenetic modifications are intimately associated with autophagy and the onset and progression of various brain diseases. Non-coding RNAs, including microRNAs, circular RNAs and long noncoding RNAs, and histone acetylation have been reported to adjust autophagy-related gene and protein expression to alleviate inflammation in neurological diseases. The present review primarily focuses on the role and mechanisms of autophagy in neuroinflammatory responses, as well as epigenetic modifications of autophagy in neuroinflammation to reveal potential therapeutic targets in central nervous system diseases.

Fisetin orchestrates neuroinflammation resolution and facilitates spinal cord injury recovery through enhanced autophagy in pro-inflammatory glial cells

BACKGROUND

Neuroinflammation, a critical component of the secondary injury cascade post-spinal cord injury, involves the activation of pro-inflammatory cells and release of inflammatory mediators. Resolution of neuroinflammation is closely linked to cellular autophagy. This study investigates the potential of Fisetin, a natural anti-inflammatory compound, to ameliorate neuroinflammation and confer spinal cord injury protection through the regulation of autophagy in pro-inflammatory cells.

METHODS

Utilizing a rat T10 spinal cord injury model with distinct treatment groups (Sham, Fisetin-treated, and Fisetin combined with autophagy inhibitor), alongside in vitro models involving lipopolysaccharide (LPS)-stimulated microglial cell activation and co-culture with neurons, we employed techniques such as transcriptomic sequencing, histological assessments (immunofluorescence staining, etc.), molecular analyses (PCR, WB, ELISA, etc.), and behavioral evaluations to discern differences in neuroinflammation, autophagy, neuronal apoptosis, and neurological function recovery.

RESULTS

Fisetin significantly augmented autophagic activity in injured spinal cord tissue, crucially contributing to neurological function recovery in spinal cord-injured rats. Fisetin's autophagy-dependent effects were associated with a reduction in neuronal apoptosis at the injury site. The treatment reduced the population of CD68+ and iNOS+ cells, coupled with decreased pro-inflammatory cytokines IL-6 and TNF-α levels, through autophagy-dependent pathways. Fisetin pre-treatment attenuated LPS-induced pro-inflammatory polarization of microglial cells, with this protective effect partially blocked by autophagy inhibition. Fisetin-induced autophagy in the injured spinal cord and pro-inflammatory microglial cells was associated with significant activation of AMPK and inhibition of mTOR.

CONCLUSION

Fisetin orchestrates enhanced autophagy in pro-inflammatory microglial cells through the AMPK-mTOR signaling pathway, thereby mitigating neuroinflammation and reducing the apoptotic effects of neuroinflammation on neurons. This mechanistic insight significantly contributes to the protection and recovery of neurological function following spinal cord injury, underscoring the vital nature of Fisetin as a potential therapeutic agent.

Role of autophagy in ischemic stroke: insights from animal models and preliminary evidence in the human disease

Stroke represents a main cause of death and permanent disability worldwide. The molecular mechanisms underlying cerebral injury in response to the ischemic insults are not completely understood. In this article, we summarize recent evidence regarding the role of autophagy in the pathogenesis of ischemic stroke by reviewing data obtained in murine models of either transient or permanent middle cerebral artery occlusion, and in the stroke-prone spontaneously hypertensive rat. Few preliminary observational studies investigating the role of autophagy in subjects at high cerebrovascular risk and in cohorts of stroke patients were also reviewed. Autophagy plays a dual role in neuronal and vascular cells by exerting both protective and detrimental effects depending on its level, duration of stress and type of cells involved. Protective autophagy exerts adaptive mechanisms which reduce neuronal loss and promote survival. On the other hand, excessive activation of autophagy leads to neuronal cell death and increases brain injury. In conclusion, the evidence reviewed suggests that a proper manipulation of autophagy may represent an interesting strategy to either prevent or reduce brain ischemic injury.

The missing hallmark of health: psychosocial adaptation

The eight biological hallmarks of health that we initially postulated (Cell. 2021 Jan 7;184(1):33-63) include features of spatial compartmentalization (integrity of barriers, containment of local perturbations), maintenance of homeostasis over time (recycling & turnover, integration of circuitries, rhythmic oscillations) and an array of adequate responses to stress (homeostatic resilience, hormetic regulation, repair & regeneration). These hallmarks affect all eight somatic strata of the human body (molecules, organelles, cells, supracellular units, organs, organ systems, systemic circuitries and meta-organism). Here we postulate that mental and socioeconomic factors must be added to this 8×8 matrix as an additional hallmark of health ("psychosocial adaptation") and as an additional stratum ("psychosocial interactions"), hence building a 9×9 matrix. Potentially, perturbation of each of the somatic hallmarks and strata affects psychosocial factors and vice versa. Finally, we discuss the (patho)physiological bases of these interactions and their implications for mental health improvement.

BOP1 contributes to the activation of autophagy in polycystic ovary syndrome via nucleolar stress response

Abnormal autophagy is one of the vital features in polycystic ovary syndrome (PCOS). However, the underlying molecular mechanisms remain unelucidated. In this study, we aimed to investigate whether Block of Proliferation 1 (BOP1) is involved in the onset of autophagy activation of granulosa cells in PCOS. Firstly, we found that BOP1 expression was significantly down-regulated in the ovaries of PCOS mice, which was associated with the development of PCOS. Next, local injection of lentiviral vectors in the ovary for the overexpression of BOP1 significantly alleviated the phenotypes of elevated androgens, disturbed estrous cycle, and abnormal follicular development in PCOS mice. Subsequently, we found that knockdown of BOP1 activated autophagy of granulosa cells in the in vitro experiments, whereas overexpression of BOP1 inhibited autophagy in both in vivo and in vitro models. Mechanistically, BOP1 knockdown triggered the nucleolus stress response, which caused RPL11 to be released from the nucleolus into the nucleoplasm and inhibited the E3 ubiquitination ligase of MDM2, thereby enhancing the stability of p53. Subsequently, P53 inhibited mTOR, thereby activating autophagy in granulosa cells. In addition, the mRNA level of BOP1 was negatively correlated with antral follicle count (AFC), body-mass index (BMI), serum androgen levels, and anti-Mullerian hormone (AMH) in patients with PCOS. In summary, our study demonstrates that BOP1 downregulation inhibits mTOR phosphorylation through activation of the p53-dependent nucleolus stress response, which subsequently contributes to aberrant autophagy in granulosa cells, revealing that BOP1 may be a key target for probing the mechanisms of PCOS.

Epigenetic regulation of autophagy in neuroinflammation and synaptic plasticity

Autophagy is a conserved cellular mechanism that enables the degradation and recycling of cellular organelles and proteins via the lysosomal pathway. In neurodevelopment and maintenance of neuronal homeostasis, autophagy is required to regulate presynaptic functions, synapse remodeling, and synaptic plasticity. Deficiency of autophagy has been shown to underlie the synaptic and behavioral deficits of many neurological diseases such as autism, psychiatric diseases, and neurodegenerative disorders. Recent evidence reveals that dysregulated autophagy plays an important role in the initiation and progression of neuroinflammation, a common pathological feature in many neurological disorders leading to defective synaptic morphology and plasticity. In this review, we will discuss the regulation of autophagy and its effects on synapses and neuroinflammation, with emphasis on how autophagy is regulated by epigenetic mechanisms under healthy and diseased conditions.

The interaction between ageing and Alzheimer's disease: insights from the hallmarks of ageing

Ageing is a crucial risk factor for Alzheimer's disease (AD) and is characterised by systemic changes in both intracellular and extracellular microenvironments that affect the entire body instead of a single organ. Understanding the specific mechanisms underlying the role of ageing in disease development can facilitate the treatment of ageing-related diseases, such as AD. Signs of brain ageing have been observed in both AD patients and animal models. Alleviating the pathological changes caused by brain ageing can dramatically ameliorate the amyloid beta- and tau-induced neuropathological and memory impairments, indicating that ageing plays a crucial role in the pathophysiological process of AD. In this review, we summarize the impact of several age-related factors on AD and propose that preventing pathological changes caused by brain ageing is a promising strategy for improving cognitive health.

Chaperone Activators

Ageing is a complex yet universal and inevitable degenerative process that results in a decline in the cellular capacity for repair and adaptation to external stresses. Therefore, maintaining the appropriate balance of the cellular proteome is crucial. In addition to the ubiquitin-proteasome and autophagy-lysosomal systems, molecular chaperones play a vital role in a sophisticated protein quality control system. Chaperones are responsible for the correct protein assembly, folding, and translocation of other proteins when cells are subjected to various stresses. The equilibrium of chaperones is pivotal for maintaining health and longevity, as a deficiency in their function and quantity can contribute to the development of various diseases and accelerate the ageing processes. Conversely, their overexpression has been associated with tumour growth and progression. In this work, we discuss recent research focused on the application of various natural and artificial substances, as well as physical and nutritional stresses, to activate molecular chaperones and prolong both life- and healthspan. Furthermore, we emphasise the significance of autophagy, apoptosis, mTOR and inflammation signalling pathways in chaperone-mediated extension of life- and healthspan.

Studying Autophagy in Microglia: Overcoming the Obstacles

In this chapter, we provide an overview of the main techniques and experimental approaches that can be used to analyze autophagy flux in microglia, the brain-resident macrophages. For this purpose, we first briefly introduce the main peculiarities of microglial biology, describe the basic mechanisms and functions of autophagy, and summarize the evidence accumulated so far on the role of autophagy in the regulation of microglial survival and functions, mainly phagocytosis and inflammation. Then, we highlight conceptual and technical aspects of autophagic recycling and microglial physiology that need to be taken into account for the accurate evaluation of autophagy flux in microglia. Finally, we describe the main assays that can be used to analyze the complete sequence of autophagosome formation and degradation or autophagy flux, mainly in cultured microglia and in vivo. The main approaches include indirect tracking of autophagosomes by autophagic enzymes such as LC3 by western blot and fluorescence-based confocal microscopy, as well as direct analysis of autophagic vesicles by electron microscopy. We also discuss the advantages and disadvantages of using these methods in specific experimental contexts and highlight the need to complement LC3 and/or electron microscopy data with analysis of other autophagic effectors and lysosomal proteins that participate in the initiation and completion of autophagy flux, respectively. In summary, we provide an experimental guide for the analysis of autophagosome turnover in microglia, emphasizing the need to combine as many markers and complementary approaches as possible to fully characterize the status of autophagy flux in microglia.