The Autophagy-Lysosomal Pathway in Neurodegeneration: A TFEB Perspective

Triple-Target Inhibition of Cholinesterase, Amyloid Aggregation, and GSK3β to Ameliorate Cognitive Deficits and Neuropathology in the Triple-Transgenic Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) poses one of the most urgent medical challenges in the 21st century as it affects millions of people. Unfortunately, the etiopathogenesis of AD is not yet fully understood and the current pharmacotherapy options are somewhat limited. Here, we report a novel inhibitor, Compound 44, for targeting cholinesterases, amyloid-β (Aβ) aggregation, and glycogen synthase kinase 3β (GSK-3β) simultaneously with the aim of achieving symptomatic relief and disease modification in AD therapy. We found that Compound 44 had good inhibitory effects on all intended targets with IC50s of submicromolar or better, significant neuroprotective effects in cell models, and beneficial improvement of cognitive deficits in the triple transgenic AD (3 × Tg AD) mouse model. Moreover, we showed that Compound 44 acts as an autophagy regulator by inducing nuclear translocation of transcription factor EB through GSK-3β inhibition, enhancing the biogenesis of lysosomes and elevating autophagic flux, thus ameliorating the amyloid burden and tauopathy, as well as mitigating the disease phenotype. Our results suggest that triple-target inhibition via Compound 44 could be a promising strategy that may lead to the development of effective therapeutic approaches for AD.

Therapeutic Effects of Hemerocallis citrina Baroni Extract on Animal Models of Neurodegenerative Diseases Through Serotonin and HLH-30/TFEB-Dependent Mechanisms

Hemerocallis citrina is an herbaceous perennial plant used in Asian cuisine and Traditional Chinese Medicine. Here, we tested the therapeutic potential of extracts (HCE30%, HCE50%, and HCN) in vivo, using models of two human genetic neurodegenerative diseases-Machado-Joseph Disease/Spinocerebellar Ataxia type 3 (MJD/SCA3) and Frontotemporal Dementia with Parkinsonism associated to chromosome 17 (FTDP-17). Chronic treatment with HCE30% extract ameliorated the motor deficits typically observed in these models. Interestingly, we found that the effect on the motor phenotype of the MJD/SCA3 model was dependent on serotonergic signaling and on the action of the HLH-30/TFEB transcription factor, known to regulate the cellular response to amino acid starvation, the autophagy and mitophagy pathways, lysosome localization and biogenesis, exocytosis, and mitochondrial biogenesis. Altogether, our findings reinforce the idea that phytochemicals act through the modulation of serotonergic neurotransmission and introduce a novel layer to the HLH-30/TFEB regulatory network. Thus, it also strengthens the use of these pathways as therapeutic targets for protein-related neurodegenerative disorders and confirms the utility of medicinal plants as a source of innovation in the quest for new therapeutic agents.

Lysosomes: guardians and healers within cells- multifaceted perspective and outlook from injury repair to disease treatment

Lysosomes, as crucial organelles within cells, carry out diverse biological functions such as waste degradation, regulation of the cellular environment, and precise control of cell signaling. This paper reviews the core functions and structural characteristics of lysosomes, and delves into the current research status of lysosomes damage repair mechanisms. Subsequently, we explore in depth the close association between lysosomes and various diseases, including but not limited to age-related chronic diseases, neuro-degenerative diseases, tumors, inflammation, and immune imbalance. Additionally, we also provide a detailed discussion of the application of lysosome-targeted substances in the field of regenerative medicine, especially the enormous potential demonstrated in key areas such as stem cell regulation and therapy, and myocardial cell repair. Though the integration of multidisciplinary research efforts, we believe that lysosomes damage repair mechanisms will demonstrate even greater application value in disease treatment and regenerative medicine.

Small-molecule activation of TFEB alleviates Niemann-Pick disease type C via promoting lysosomal exocytosis and biogenesis

Niemann-Pick disease type C (NPC) is a devastating lysosomal storage disease characterized by abnormal cholesterol accumulation in lysosomes. Currently, there is no treatment for NPC. Transcription factor EB (TFEB), a member of the microphthalmia transcription factors (MiTF), has emerged as a master regulator of lysosomal function and promoted the clearance of substrates stored in cells. However, it is not known whether TFEB plays a role in cholesterol clearance in NPC disease. Here, we show that transgenic overexpression of TFEB, but not TFE3 (another member of MiTF family) facilitates cholesterol clearance in various NPC1 cell models. Pharmacological activation of TFEB by sulforaphane (SFN), a previously identified natural small-molecule TFEB agonist by us, can dramatically ameliorate cholesterol accumulation in human and mouse NPC1 cell models. In NPC1 cells, SFN induces TFEB nuclear translocation via a ROS-Ca2+-calcineurin-dependent but MTOR-independent pathway and upregulates the expression of TFEB-downstream genes, promoting lysosomal exocytosis and biogenesis. While genetic inhibition of TFEB abolishes the cholesterol clearance and exocytosis effect by SFN. In the NPC1 mouse model, SFN dephosphorylates/activates TFEB in the brain and exhibits potent efficacy of rescuing the loss of Purkinje cells and body weight. Hence, pharmacological upregulating lysosome machinery via targeting TFEB represents a promising approach to treat NPC and related lysosomal storage diseases, and provides the possibility of TFEB agonists, that is, SFN as potential NPC therapeutic candidates.

TFEB-dependent autophagy-lysosomal pathway is required for NRF2-driven antioxidative action in obstructive sleep apnea-induced neuronal injury

Nearly one billion individuals worldwide suffer from obstructive sleep apnea (OSA) and are potentially impacted by related neurodegeneration. TFEB is considered a master regulator of autophagy and lysosomal biogenesis, but little is known about its role in neuronal oxidative stress and resultant injury induced by OSA. This study aimed to investigate these issues. Here, we demonstrated that neuronal TFEB induction is repressed in OSA mouse models. Activation of a TFEB-dependent autophagy-lysosomal pathway (ALP) reduces hippocampal neuronal cell death and mitigates OSA-related cognitive impairment. Neuronal NRF2 induction was also found to be defective in OSA mouse models. A series of staining assays for HO1, SOD3, ROS, GSH, 8-OHdG, MDA and PI revealed that enhancement of NRF2 expression restores neuronal redox balance and protects hippocampal neurons. We then identified a novel interplay between TFEB-dependent ALP and NRF2-mediated relief of oxidative stress. Inhibition of NRF2 hinders TFEB expression and lysosomal biogenesis. Conversely, knockdown of TFEB or blocking autophagy dampens the antioxidative effect of NRF2. Our findings highlight the unexpected and crucial role of TFEB-dependent ALP as a downstream event of NRF2 in NRF2-promoted redox balance. This study provides novel insights into the mechanism behind NRF2-driven antioxidative action and the regulation of TFEB-dependent ALP.

Actions of dexmedetomidine in regulating NLRP3 in postoperative cognitive dysfunction in aged mice via the autophagy-lysosome pathway

BACKGROUND AND PURPOSE

Autophagy-lysosomal pathway dysfunction leads to postoperative cognitive dysfunction (POCD). Dexmedetomidine (Dex) improves POCD, and we probed the effects of Dex on autophagy-lysosomal pathway dysfunction in a POCD model.

EXPERIMENTAL APPROACH

A POCD mouse model was established and intraperitoneally injected with Dex. Cognitive function was evaluated by Morris water maze/open field test/novel object recognition assay. Levels of neurotransmitters/inflammatory cytokines in hippocampus, and NLRP3/ASC/Cleaved Caspase-1 proteins were determined by ELISA/Western blot. NLRP3 inflammasome-mediated microglial activation/astrocyte A1 differentiation in the hippocampal CA1 region were assessed by immunofluorescence assay. BV-2 cells were treated with lipopolysaccharide (LPS) and Dex and/or the NLRP3 inflammasome activator Nigericin, and transfected with si-TFEB for co-culture with primary reactive astrocytes (RAs) to verify the function of Dex in vitro.

KEY RESULTS

Dex alleviated cognitive dysfunction in POCD mice and repressed NLRP3 inflammasome-mediated microglial activation and astrocyte A1 differentiation. NLRP3 inflammasome activation partially reversed the protective effect of Dex on the POCD condition. In vitro experiments verified the inhibitory properties of Dex on microglial activation and astrocyte A1 differentiation. Dex induces TFEB nuclear translocation, microglial autophagy and lysosomal biogenesis. By activating the autophagy-lysosome pathway, Dex regulated NLRP3 inflammasome-mediated microglial activation, inhibited astrocyte A1 differentiation and alleviated POCD in vivo.

CONCLUSION AND IMPLICATIONS

Dex regulates NLRP3 inflammasome-mediated hippocampal microglial activation by promoting TFEB nuclear translocation and activating the autophagy-lysosome pathway and inhibits astrocyte A1 differentiation, thereby alleviating POCD.

Heavy metal-induced disruption of the autophagy-lysosomal pathway: implications for aging and neurodegenerative disorders

Heavy metals such as lead, mercury, cadmium, magnesium, manganese, arsenic, copper pose considerable threats to neuronal health and are increasingly recognized as factors contributing to aging-related neurodegeneration. Exposure to these environmental toxins disrupts cellular homeostasis, resulting in oxidative stress and compromising critical cellular processes, particularly the autophagy-lysosomal pathway. This pathway is vital for preserving cellular integrity by breaking down damaged proteins and organelles; however, toxicity from heavy metals can hinder this function, leading to the buildup of harmful substances, inflammation, and increased neuronal injury. As individuals age, the consequences of neurodegeneration become more significant, raising the likelihood of developing disorders like Alzheimer's and Parkinson's disease. This review explores the intricate relationship between heavy metal exposure, dysfunction of the autophagy-lysosomal pathway, and aging-related neurodegeneration, emphasizing the urgent need for a comprehensive understanding of these mechanisms. The insights gained from this analysis are crucial for creating targeted therapeutic approaches aimed at alleviating the harmful effects of heavy metals on neuronal health and improving cellular resilience in aging populations.

Nobiletin-mediated autophagy mitigates nanoplastic-induced toxicity in human intestinal Caco-2 cells

The presence of nanoplastics (NPs), which cause oxidative stress and damage to the cell structure due to the breakdown of microplastics (MPs), poses considerable ecological and health challenges. This study investigated the protective role of nobiletin (NOB), a flavonoid derived from citrus peel, in modulating autophagy and mitigating NP-induced toxicity in human intestinal Caco-2 cells. The Caco-2 cells were treated with NPs and varying concentrations of NOB to evaluate cell viability, apoptosis, and autophagic activity. We observed that exposure to NPs resulted in a concentration-dependent decrease in cell viability and an increase in the expression of apoptosis markers. Exposure to NPs reduced Caco-2 cell viability and disrupted autophagic processes by decreasing LC3B and increasing p62 levels, indicating impaired autophagy. NOB treatment reversed these effects by enhancing autophagic activity by upregulating LC3B and downregulating p62. Furthermore, NOB improved lysosomal integrity and decreased apoptotic markers such as Bax and cleaved caspase-3 while increasing Bcl-2 expression. NOB also facilitated the nuclear translocation of transcription factor EB through activating AMP-activated protein kinase (AMPK) and inhibiting mechanistic target of rapamycin (mTOR), promoting cellular detoxification and homeostasis. NOB has the potential as a therapeutic agent that leverages the autophagic pathway to mitigate the adverse effects of NPs, suggesting a novel approach for managing NPs toxicity in human intestinal Caco-2 cells.

Lysosomal Dysfunction in Amyotrophic Lateral Sclerosis: A Familial Case Linked to the p.G376D TARDBP Mutation

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease affecting motor neurons. Consequent to the loss of these cells, neuromuscular functions decline, causing progressive weakness, muscle wasting, and paralysis, leading to death in 2 to 5 years. More than 90% of ALS cases are sporadic, while the remaining 10% of cases are familial, due to mutations in 40 different genes. One of the most common genes to be mutated in ALS is TARDBP (transactive response DNA binding protein 43), which encodes TDP-43 (TAR DNA-binding protein 43). A mutation in exon 6 of TARDBP causes the aminoacidic substitution G376D in the C-terminal region of TDP-43, leading to its cytoplasmic mislocalization and aggregation. In fibroblasts derived from patients carrying this mutation, we found a strong increase in lysosome number, with overexpression and higher nuclear translocation of the transcription factor TFEB. In contrast, lysosomal functionality was deeply compromised. Interestingly, lysosomal activity was unaffected at an early stage of the disease, worsening in more advanced stages. Moreover, we observed the same pathological phenotype in iPSC (induced pluripotent stem cells)-derived patient motor neurons carrying the G376D mutation. Therefore, this mutation compromises the functionality of lysosomes, possibly contributing to neurodegeneration.

HSP90 N-terminal inhibition promotes mitochondria-derived vesicles related metastasis by reducing TFEB transcription via decreased HSP90AA1-HCFC1 interaction in liver cancer

Cancer cells compensate with increasing mitochondria-derived vesicles (MDVs) to maintain mitochondrial homeostasis, when canonical MAP1LC3B/LC3B (microtubule associated protein 1 light chain 3 beta)-mediated mitophagy is lacking. MDVs promote the transport of mitochondrial components into extracellular vesicles (EVs) and induce tumor metastasis. Although HSP90 (heat shock protein 90) chaperones hundreds of client proteins and its inhibitors suppress tumors, HSP90 inhibitors-related chemotherapy is associated with unexpected metastasis. Herein, we find that HSP90 inhibitor causes mitochondrial damage but stimulates the low LC3-induced MDVs and the release of MDVs-derived EVs. However, why LC3 decreases and what is the transcriptional regulatory mechanism of MDVs formation under HSP90 inhibition remain unknown. Because TFEB (transcription factor EB) is the most important mitophagy transcription factor, and the HSP90 client HCFC1 (host cell factor C1) regulates TFEB transcription, there should be a hidden connection between TFEB, HCFC1 and HSP90 in MDVs formation. Our results support the idea that HSP90 N-terminal inhibition reduces TFEB transcription via decreased HSP90AA1-HCFC1 interaction, which prevents HCFC1 from binding to the TFEB proximal promoter region. Decreased TFEB transcription and consequently reduced LC3, ultimately promoted MDVs formation. Blocking MDVs formation with the microtubule inhibitor nocodazole (NOC) activates the HCFC1-TFEB-LC3 axis, weakens HSP90 inhibitors-induced MDVs and the release of MDVs-derived EVs, inhibits the growth of tumor cell spheres and primary liver tumors, and reduces the extravasation of cancer cells to secondary metastatic sites. Taken together, these data suggest that combination therapy should be used to reduce the metastatic risk of low TFEB-triggered-MDVs formation caused by HSP90 inhibitors.Abbreviation: ACIs: ATP-competitive inhibitors; BaFA1: bafilomycin A1; CCCP: carbonyl cyanide 3-chlorophenylhydrazone; ChIP: chromatin immunoprecipitation; CHX: cycloheximide; CTD: C-terminal domain; EVs: extracellular vesicles; HCFC1: host cell factor C1; HSP90: heat shock protein 90; ILVs: intralumenal vesicles; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MD: middle domain; MDVs: mitochondria-derived vesicles; MQC: mitochondrial quality control; ΔΨm: mitochondrial membrane potential; MVBs: multivesicular bodies; NB: novobiocin; TEM: transmission electron microscopy; TFEB: transcription factor EB; TFs: transcription factors. NOC: nocodazole; NTD: N-terminal nucleotide binding domain; OCR: oxygen consumption rate; RFP: red fluorescent protein; ROS: reactive oxygen species; STA9090: Ganetespib; VPS35: VPS35 retromer complex component.

Neurexin1 level in Huntington's Disease and decreased Neurexin1 in disease progression

Huntington's disease (HD) is a neurodegenerative disorder characterized by the presence of abnormally expanded polyglutamine tracts in huntingtin protein (HTT). Mutant HTT disrupts synaptic transmission and plasticity, particularly in the striatum and cortex, leading to early dysfunctions, such as altered neurotransmitter release, impaired synaptic vesicle recycling, and disrupted postsynaptic receptor function. Synaptic loss precedes neuronal degeneration and contributes to disease progression. Neurexin1 (NRXN1), a synaptic cell adhesion molecule primarily located in the presynaptic membrane, plays a crucial role in maintaining synaptic integrity. The present study investigated the role of NRXN1 in HD. This study researched whether the changed level has been related to expanded polyQ stretch and disease progression. Here, we report a reduction in NRXN1 levels in post-symptomatic HD mice and in neuronal cells expressing abnormally expanded polyQ tracts. Mutant HTT was found to decrease NRXN1 levels while increasing LAMP2A levels, which promotes lysosomal degradation of NRXN1. In HD cells expressing Q111, downregulated LAMP2A restored NRXN1 levels and maintained cell proliferation compared with cells expressing Q7. These findings suggest that NRXN1 is regulated by LAMP2A-mediated way and that decreased NRXN1 levels are associated with symptomatic progression and neuronal cell loss in HD.

The role of GSK3β signaling mediated lysosomal biosynthesis dysregulation in fluoride-induced neurological impairment

Neurological dysfunction induced by fluoride is still one of major concern worldwide, yet the underlying mechanisms remain elusive. To explore whether fluoride disrupts lysosomal biosynthesis via the GSK3β signaling, leading to neurological damage, both in vivo rat models and in vitro PC12 cell models were conducted. Subsequent findings revealed reduced spatial learning and memory abilities, decreased hippocampal neurons, and disrupted neuronal arrangement in NaF-treated rats. In vitro, PC12 cells exhibited decreased cell viability and increased apoptosis rates after NaF treatment for 24 h. Moreover, immunofluorescence assays demonstrated that there is a reduction in the number of mature lysosomes and an increase in immature lysosomes in NaF-treated PC12 cells, evident by decreased co-localization of LAMP1 with Arl8b, and increased co-localization of LAMP1 with Rab7. Furthermore, both in vivo and in vitro, the protein expression of cleaved caspase-3 was upregulated, whereas the protein expressions of TFEB and CTSB were downregulated. The GSK3β signaling activation was detected, and this was confirmed by silencing GSK3β with siRNA in vitro. Collectively, these results indicate that NaF can impair lysosomal biosynthesis via GSK3β signaling, promoting neuronal apoptosis, and consequently impairing neurological function in rats.

Melanin deposition and key molecular features in Xenopus tropicalis oocytes

BACKGROUND

Melanin pigmentation in oocytes is a critical feature for both the esthetic and developmental aspects of oocytes, influencing their polarity and overall development. Despite substantial knowledge of melanogenesis in melanocytes and retinal pigment epithelium cells, the molecular mechanisms underlying oocyte melanogenesis remain largely unknown.

RESULTS

Here, we compare the oocytes of wild-type, tyr-/- and mitf-/- Xenopus tropicalis and found that mitf-/- oocytes exhibit normal melanin deposition at the animal pole, whereas tyr-/- oocytes show no melanin deposition at this site. Transmission electron microscopy confirmed that melanogenesis in mitf-/- oocytes proceeds normally, similar to wild-type oocytes. Transcriptomic analysis revealed that mitf-/- oocytes still express melanogenesis-related genes, enabling them to complete melanogenesis. Additionally, in Xenopus tropicalis oocytes, the expression of the MiT subfamily factor tfe3 is relatively high, while tfeb, mitf, and tfec levels are extremely low. The expression pattern of tfe3 is similar to that of tyr and other melanogenesis-related genes. Thus, melanogenesis in Xenopus tropicalis oocytes is independent of Mitf and may be regulated by other MiT subfamily factors such as Tfe3, which control the expression of genes like tyr, dct, and tyrp1. Furthermore, transcriptomic data revealed that changes in the expression of genes related to mitochondrial cloud formation represent the most significant molecular changes during oocyte development.

CONCLUSIONS

Overall, these findings suggest that further elucidation of Tyr-dependent and Mitf-independent mechanisms of melanin deposition at the animal pole will enhance our understanding of melanogenesis and Oogenesis.

RONIN/HCF1-TFEB Axis Protects Against D-Galactose-Induced Cochlear Hair Cell Senescence Through Autophagy Activation

Age-related hearing loss is characterized by senescent inner ear hair cells (HCs) and reduced autophagy. Despite the improved understanding of these processes, detailed molecular mechanisms underlying cochlear HC senescence remain unclear. Transcription Factor EB (TFEB), a key regulator of genes associated with autophagy and lysosomes, crucially affects aging-related illnesses. However, intricate regulatory networks that influence TFEB activity remain to be thoroughly elucidated. The findings revealed that RONIN (THAP11), through its interaction with host cell factor C1 (HCF1/HCFC1), modulated the transcriptional activity of Tfeb, thus contributing to the mitigation (D-galatactose [D-gal]) senescent HC loss. Specifically, RONIN overexpression improved autophagy levels and lysosomal activity and attenuated changes associated with the senescence of HCs triggered by D-gal. These findings highlight the possibility of using RONIN as a viable therapeutic target to ameliorate presbycusis by enhancing the TFEB function.

Changes in the pH value of the human brain in Alzheimer's disease pathology correlated with CD68-positive microglia: a community-based autopsy study in Beijing, China

The microenvironment of the central nervous system is highly complex and plays a crucial role in maintaining the function of neurons, which influences Alzheimer's disease (AD) progression. The pH value of the brain is a critical aspect of the brain microenvironment in regulating various physiological processes. However, the specific mechanisms and role of this mechanism are not yet fully understood. To better understand the relationship between brain pH and AD, we analyzed the brain pH of the frontal lobe and AD pathology scores in postmortem brain samples from 368 donors from the National Human Brain Bank for Development and Function, 96 of whom were diagnosed with AD pathology. Analysis revealed a significant decrease in brain pH in AD patients, which was strongly correlated with β-amyloid plaques and phosphorylated tau proteins. Here, we elucidated the differential protein expression level of CD68-positive microglia between control and AD groups (t = 3.198, df = 20, P = 0.0045), and its protein expression level was correlated negatively with the brain pH value (F = 26.93, p = 0.0006). Our findings revealed that increased activation of CD68-positive microglia and disrupted lysosomal homeostasis in the pathological brain tissue of individuals with AD may lead to a decrease in brain pH.

Phase-separated Condensates in Autophagosome Formation and Autophagy Regulation

Biomacromolecules partition into numerous types of biological condensates or membrane-less organelles via liquid-liquid phase separation (LLPS). Newly formed liquid-like condensates may further undergo phase transition to convert into other material states, such as gel or solid states. Different biological condensates possess distinct material properties to fulfil their physiological functions in diverse cellular pathways and processes. Phase separation and condensates are extensively involved in the autophagy pathway. The autophagosome formation sites in both yeast and multicellular organisms are assembled as phase-separated condensates. TORC1, one of the core regulators of the autophagy-lysosome pathway, is subject to nonconventional regulation by multiple biological condensates. TFEB, the master transcription factor of the autophagy-lysosome pathway, phase separates to assemble liquid-like condensates involved in transcription of autophagic and lysosomal genes. The behaviors and transcriptional activity of TFEB condensates are governed by their material properties, thus suggesting novel autophagy intervention strategies. The phase separation process and the resulting condensates are emerging therapeutic targets for autophagy-related diseases.

Manganese exposure induces parkinsonism-like symptoms by Serpina3n-TFEB-v/p-ATPase signaling mediated lysosomal dysfunction

Manganese (Mn) is a neurotoxin that has been etiologically linked to the development of neurodegenerative diseases in the case of overexposure. It is widely accepted that overexposure to Mn leads to manganism, which has clinical symptoms similar to Parkinson's disease (PD), and is referred to as parkinsonism. Astrocytes have been reported to scavenge and degrade extracellular α-synuclein (α-Syn) in the brain. However, the mechanisms of Mn-induced neurotoxicity associated with PD remain unclear. Serpina3n is highly expressed in astrocytes and has been implicated in several neuropathologies. The role Serpina3n plays in Mn neurotoxicity and PD pathogenesis is still unknown. Here, we used wild-type and Serpina3n knockout (KO) C57BL/6 J mice with i.p. injection of 32.5 mg/kg MnCl2 once a day for 6 weeks to elucidate the role of Serpina3n in Mn-caused neurotoxicity regarding parkinsonism pathogenesis. We performed behavioral tests (open field, suspension and pole-climbing tests) to observe Mn-induced motor changes, immunohistochemistry to detect Mn-induced midbrain changes, and Western blot to detect Mn-induced changes of protein expression. It was found that Serpina3n KO markedly alleviated Mn neurotoxicity in mice by attenuating midbrain dopaminergic neuron damage and ameliorating motor deficits. Furthermore, using immunofluorescence colocalization analysis, Western blot and quantitative real-time PCR on Mn-treated C8-D1A cells, we found that Serpina3n KO significantly improved astrocytic α-Syn clearance by suppressing Mn-induced lysosomal dysfunction. Reduced transcription factor EB (TFEB)-v/p-ATPase signaling is responsible for the impairment of the lysosomal acidic environment. These novel findings highlight Serpina3n as a detrimental factor in Mn neurotoxicity associated with parkinsonism, capture the novel role of Serpina3n in regulating lysosomal function, and provide a potential target for antagonizing Mn neurotoxicity and curing parkinsonism in humans.

Regulatory Mechanisms and Therapeutic Implications of Lysosomal Dysfunction in Alzheimer's Disease

Alzheimer's disease (AD) is characterized by the accumulation of amyloid-beta (Aβ) plaques, neurofibrillary tangles (NFTs) formed from hyperphosphorylated Tau, and widespread neuronal loss. The autophagy-lysosomal pathway plays a crucial role in maintaining cellular homeostasis by degrading and recycling of damaged organelles and aggregate amyloid proteins implicated in AD. Lysosomes are key effectors of autophagic process, responsible for the breakdown of a variety of damaged organelles and aggregate or dysfunctional proteins. This review examines the role of lysosomal dysfunction in AD pathophysiology, focusing on genetic factors, acidification abnormalities, and other contributing factors. We also explore the involvement of lysosomal dysfunction of microglia in AD pathology, and cover the role of lysosomal stress response (LSR) in cellular response to neuronal injury associated with AD. Furthermore, we discuss potential therapeutic strategies targeting lysosomal proteolysis pathway and addressing lysosomal dysfunction for AD treatment, including the pharmacologically activating lysosomal activity, regulating TFEB, and considering other emerging approaches.

Protective Role of Electroacupuncture Against Cognitive Impairment in Neurological Diseases

Many neurological diseases can lead to cognitive impairment in patients, which includes dementia and mild cognitive impairment and thus create a heavy burden both to their families and public health. Due to the limited effectiveness of medications in treating cognitive impairment, it is imperative to develop alternative treatments. Electroacupuncture (EA), a required method for Traditional Chinese Medicine, has the potential treatment of cognitive impairment. However, the molecular mechanisms involved have not been fully elucidated. Considering the current research status, preclinical literature published within the ten years until October 2022 was systematically searched through PubMed, Web of Science, MEDLINE, Ovid, and Embase. By reading the titles and abstracts, a total of 56 studies were initially included. It is concluded that EA can effectively ameliorate cognitive impairment in preclinical research of neurological diseases and induce potentially beneficial changes in molecular pathways, including Alzheimer's disease, vascular cognitive impairment, chronic pain, and Parkinson's disease. Moreover, EA exerts beneficial effects through the same or diverse mechanisms for different disease types, including but not limited to neuroinflammation, neuronal apoptosis, neurogenesis, synaptic plasticity, and autophagy. However, these findings raise further questions that need to be elucidated. Overall, EA therapy for cognitive impairment is an area with great promise, even though more research regarding its detailed mechanisms is warranted.

Itaconic acid ameliorates necrotizing enterocolitis through the TFEB-mediated autophagy-lysosomal pathway

Excessive autophagy has been implicated in the pathogenesis of necrotizing enterocolitis (NEC), yet the molecular underpinnings of the autophagy-lysosomal pathway (ALP) in NEC are not well characterized. This study aimed to elucidate alterations within the ALP in NEC by employing RNA sequencing on intestinal tissues obtained from affected infants. Concurrently, we established animal and cellular models of NEC to assess the therapeutic efficacy of itaconic acid (ITA). Our results indicate that the ALP is significantly disrupted in NEC. Notably, ITA was found to modulate the ALP, enhancing autophagic flux and lysosomal function, which consequently alleviated NEC symptoms. Further analysis revealed that ITA's beneficial effects are mediated through the promotion of TFEB nuclear translocation, thereby augmenting the ALP. These findings suggest that targeting the ALP with ITA to modulate TFEB activity may represent a viable therapeutic approach for NEC.

20-Deoxyingenol Activates Mitophagy Through TFEB and Promotes Functional Recovery After Spinal Cord Injury

Spinal cord injury (SCI) can lead to permanent paralysis and various motor, sensory and autonomic nervous system dysfunction. The complex pathophysiological processes limit the effectiveness of many clinical treatments. Mitochondria has been reported to play a key role in the pathogenesis of SCI; while mitophagy is a protective mechanism against mitochondrial dysfunction. However, there is recently little drugs that may targeted activate mitophagy to treat SCI. In this study, we evaluated the role of 20-Deoxyingenol (20-DOI) in SCI and explored its potential mechanisms. We used a SCI rat model and evaluated the functional outcomes after the injury. Western blotting and immunofluorescence techniques were used to analyze the levels of mitophagy, apoptosis, and TFEB-related signaling pathways. Our research results show that 20-DOI significantly improves the apoptosis of neural cells after TBHP stimulation and functional recovery after spinal cord injury. In addition, mitophagy, TFEB levels, and apoptosis are related to the mechanism of 20-DOI treatment for spinal cord injury. Specifically, our research results indicate that 20-DOI restored the autophagic flux after injury, thereby inducing mitophagy, eliminating the accumulation of Cyto C, and inhibiting apoptosis. Further mechanism research suggests that 20-DOI may regulate mitophagy by promoting TFEB nuclear translocation. These results indicate that 20-DOI can significantly promote recovery after spinal cord injury, which may be a promising treatment method for spinal cord injury.

TMEM106B knockdown exhibits a neuroprotective effect in Parkinson's disease models via regulating autophagy-lysosome pathway

BACKGROUND

TMEM106B, a lysosomal transmembrane protein, has been reported to be associated with Parkinson's disease (PD). However, the precise physiopathologic mechanism of TMEM106B in PD remains unclear.

OBJECTIVE

This study aimed to explore the influence of TMEM106B on the autophagy-lysosome pathway (ALP) in PD.

METHODS

55 patients with PD and 40 healthy controls were enrolled. RT-qPCR and ELISA were employed to assess the levels of TMEM106B. In vitro and in vivo models of PD, Lentivirus-shTMEM106B and AAV-shTMEM106B were used to knockdown the expression of TMEM106B. Behavioral experiments, western blot, immunofluorescence, and immunohistochemistry were used to detect the effect of TMEM106B on the ALP process.

RESULTS

We found that the levels of TMEM106B were increased in the PD patients and PD models. TMEM106B knockdown markedly improved the motor deficits and tyrosine hydroxylase (TH) expression of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned mice. TMEM106B knockdown promoted α-syn clearance by regulating the ALP process in MPP+-induced SH-SY5Y cells and MPTP-treated mice. Further studies revealed that TMEM106B knockdown might activate ALP through activating AMPK-mTOR-TFEB axis. Furthermore, TMEM106B may play a vital role in the ALP by mediating the expression of TDP43.

CONCLUSIONS

Taken together, our study suggests that TMEM106B knockdown mediates the ALP pathway, leading to a decrease in α-syn, providing a new direction and perspective for the regulation of autophagy in PD.

Ubiquitin regulatory X (UBX) domain-containing protein 6 is essential for autophagy induction and inflammation control in macrophages

Ubiquitin regulatory X (UBX) domain-containing protein 6 (UBXN6) is an essential cofactor for the activity of the valosin-containing protein p97, an adenosine triphosphatase associated with diverse cellular activities. Nonetheless, its role in cells of the innate immune system remains largely unexplored. In this study, we report that UBXN6 is upregulated in humans with sepsis and may serve as a pivotal regulator of inflammatory responses via the activation of autophagy. Notably, the upregulation of UBXN6 in sepsis patients was negatively correlated with inflammatory gene profiles but positively correlated with the expression of Forkhead box O3, an autophagy-driving transcription factor. Compared with those of control mice, the macrophages of mice subjected to myeloid cell-specific UBXN6 depletion exhibited exacerbated inflammation, increased mitochondrial oxidative stress, and greater impairment of autophagy and endoplasmic reticulum-associated degradation pathways. UBXN6-deficient macrophages also exhibited immunometabolic remodeling, characterized by a shift to aerobic glycolysis and elevated levels of branched-chain amino acids. These metabolic shifts amplify mammalian target of rapamycin pathway signaling, in turn reducing the nuclear translocation of the transcription factor EB and impairing lysosomal biogenesis. Together, these data reveal that UBXN6 serves as an activator of autophagy and regulates inflammation to maintain immune system suppression during human sepsis.

EGCG suppressed activation of hepatic stellate cells by regulating the PLCE1/IP3/Ca2+ pathway

(-)-Epigallocatechin-3-O-gallate (EGCG), one of the green tea catechins, exhibits significant antioxidant properties that play an essential role in various diseases. However, the functional role and underlying mechanism of EGCG in stimulating of hepatic stellate cells (HSCs) remain unexplored in transcriptomics sequencing studies. The present study suggests that oral administration of EGCG at a dosage of 200 mg/kg/day for a duration of four weeks exhibits significant therapeutic potential in a murine model of liver fibrosis induced by CCl4. The activation of HSCs in vitro was dose-dependently inhibited by EGCG. The sequencing analysis data reveled that EGCG exerted a regulatory effect on the calcium signal in mouse HSCs, resulting in a decrease in calcium ion concentration. Further analysis revealed that EGCG inhibited the expression of phospholipase C epsilon-1 (PLCE1) and inositol 1, 4, 5-trisphosphate (IP3) in activated mouse HSCs. Additionally, EGCG contributes to the reduction the concentration of calcium ions by regulating PLCE1. After the knockdown of PLCE1, free calcium ion concentrations decreased, resulting in the inhibition of both cell proliferation and migration. Interestingly, the expression of PLCE1 and cytosolic calcium levels were regulated by reactive oxygen species(ROS). Furthermore, our findings suggest that ROS might inhibit the expression of PLCE1 by inhibiting TFEB, a transcription activator involved in the nuclear translocation process. Our study provided novel evidence regarding the regulatory effects of EGCG on activated HSCs (aHSCs) in mice by the calcium signaling pathway, emphasizing the crucial role of PLCE1 within the calcium signaling network of HSCs. The proposition was also made that PLCE1 holds promise as a novel therapeutic target for murine liver fibrosis.

TFEB signaling promotes autophagic degradation of NLRP3 to attenuate neuroinflammation in diabetic encephalopathy

Diabetic encephalopathy (DE), a neurological complication of diabetes mellitus, has an unclear etiology. Shreds of evidence show that the nucleotide-binding oligomerization domain-like receptor family protein 3 (NLRP3) inflammasome-induced neuroinflammation and transcription factor EB (TFEB)-mediated autophagy impairment may take part in DE development. The cross talk between these two pathways and their contribution to DE remains to be explored. A mouse model of type 2 diabetes mellitus (T2DM) exhibiting cognitive dysfunction was created, along with high-glucose (HG) cultured BV2 cells. Following, 3-methyladenine (3-MA) and rapamycin were used to modulate autophagy. To evaluate the potential therapeutic benefits of TFEB in DE, we overexpressed and knocked down TFEB in both mice and cells. Autophagy impairment and NLRP3 inflammasome activation were noticed in T2DM mice and HG-cultured BV2 cells. The inflammatory response caused by NLRP3 inflammasome activation was decreased by rapamycin-induced autophagy enhancement, while 3-MA treatment further deteriorated it. Nuclear translocation and expression of TFEB were hampered in HG-cultured BV2 cells and T2DM mice. Exogenous TFEB overexpression boosted NLRP3 degradation via autophagy, which in turn alleviated microglial activation as well as ameliorated cognitive deficits and neuronal damage. In addition, TFEB knockdown exacerbated neuroinflammation by decreasing autophagy-mediated NLRP3 degradation. Our findings have unraveled the pathogenesis of a previously underappreciated disease, implying that the activation of NLRP3 inflammasome and impairment of autophagy in microglia are significant etiological factors in the DE. The TFEB-mediated autophagy pathway can reduce neuroinflammation by enhancing NLRP3 degradation. This could potentially serve as a viable and innovative treatment approach for DE.NEW & NOTEWORTHY This article delves into the intricate connections between inflammation, autophagy, diabetes, and neurodegeneration, with a particular focus on a disease that is not yet fully understood-diabetic encephalopathy (DE). TFEB emerges as a pivotal regulator in balancing autophagy and inflammation in DE. Our findings highlight the crucial function of the TFEB-mediated autophagy pathway in mitigating inflammatory damage in DE, suggesting a new treatment strategy.

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

Alcohol consumption is believed to affect Alzheimer's disease (AD) risk, but the contributing mechanisms are not well understood. A potential mediator of the proposed alcohol-AD connection is autophagy, a degradation pathway that maintains organelle and protein homeostasis. Autophagy is regulated through the activity of Transcription factor EB (TFEB), which promotes lysosome and autophagy-related gene expression. The purpose of this study is to explore whether chronic alcohol consumption worsens the age-related decline in TFEB-mediated lysosomal biogenesis in the brain and exacerbates cognitive decline associated with aging. To explore the effect of alcohol on brain TFEB and autophagy, we exposed young (3-month-old) and aged (23-month-old) mice to two alcohol-feeding paradigms and assessed biochemical, transcriptome, histology, and behavioral endpoints. In young mice, alcohol decreased hippocampal nuclear TFEB staining but increased SQSTM1/p62, LC3-II, ubiquitinated proteins, and phosphorylated Tau. Hippocampal TFEB activity was lower in aged mice than it was in young mice, and Gao-binge alcohol feeding did not worsen the age-related reduction in TFEB activity. Morris Water and Barnes Maze spatial memory tasks were used to characterize the effects of aging and chronic alcohol exposure (mice fed alcohol for 4 weeks). The aged mice showed worse spatial memory acquisition in both tests. Alcohol feeding slightly impaired spatial memory in the young mice, but had little effect or even slightly improved spatial memory acquisition in the aged mice. In conclusion, aging produces greater reductions in brain autophagy flux and impairment of spatial memory than alcohol consumption.

A crosstalk between autophagy and apoptosis in intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a severe condition that devastatingly harms human health and poses a financial burden on families and society. Bcl-2 Associated X-protein (Bax) and B-cell lymphoma 2 (Bcl-2) are two classic apoptotic markers post-ICH. Beclin 1 offers a competitive architecture with that of Bax, both playing a vital role in autophagy. However, the interaction between Beclin 1 and Bcl-2/Bax has not been conjunctively analyzed. This review aims to examine the crosstalk between autophagy and apoptosis in ICH by focusing on the interaction and balance of Beclin 1, Bax, and Bcl-2. We also explored the therapeutic potential of Western conventional medicine and traditional Chinese medicine (TCM) in ICH via controlling the crosstalk between autophagy and apoptosis.

The emerging role of exercise in Alzheimer's disease: Focus on mitochondrial function

Alzheimer's disease (AD) is an age-related neurodegenerative disease characterized by memory impairment and cognitive dysfunction, which eventually leads to the disability and mortality of older adults. Although the precise mechanisms by which age promotes the development of AD remains poorly understood, mitochondrial dysfunction plays a central role in the development of AD. Currently, there is no effective treatment for this debilitating disease. It is well accepted that exercise exerts neuroprotective effects by ameliorating mitochondrial dysfunction in the neurons of AD, which involves multiple mechanisms, including mitochondrial dynamics, biogenesis, mitophagy, transport, and signal transduction. In addition, exercise promotes mitochondria communication with other organelles in AD neurons, which should receive more attentions in the future.

Potential application of natural compounds in ischaemic stroke: Focusing on the mechanisms underlying "lysosomocentric" dysfunction of the autophagy-lysosomal pathway

Ischaemic stroke (IS) is the second leading cause of death and a major cause of disability worldwide. Currently, the clinical management of IS still depends on restoring blood flow via pharmacological thrombolysis or mechanical thrombectomy, with accompanying disadvantages of narrow therapeutic time window and risk of haemorrhagic transformation. Thus, novel pathophysiological mechanisms and targeted therapeutic candidates are urgently needed. The autophagy-lysosomal pathway (ALP), as a dynamic cellular lysosome-based degradative process, has been comprehensively studied in recent decades, including its upstream regulatory mechanisms and its role in mediating neuronal fate after IS. Importantly, increasing evidence has shown that IS can lead to lysosomal dysfunction, such as lysosomal membrane permeabilization, impaired lysosomal acidity, lysosomal storage disorder, and dysfunctional lysosomal ion homeostasis, which are involved in the IS-mediated defects in ALP function. There is tightly regulated crosstalk between transcription factor EB (TFEB), mammalian target of rapamycin (mTOR) and lysosomal function, but their relationship remains to be systematically summarized. Notably, a growing body of evidence emphasizes the benefits of naturally derived compounds in the treatment of IS via modulation of ALP function. However, little is known about the roles of natural compounds as modulators of lysosomes in the treatment of IS. Therefore, in this context, we provide an overview of the current understanding of the mechanisms underlying IS-mediated ALP dysfunction, from a lysosomal perspective. We also provide an update on the effect of natural compounds on IS, according to their chemical structural types, in different experimental stroke models, cerebral regions and cell types, with a primary focus on lysosomes and autophagy initiation. This review aims to highlight the therapeutic potential of natural compounds that target lysosomal and ALP function for IS treatment.

TFEB/LAMP2 contributes to PM0.2-induced autophagy-lysosome dysfunction and alpha-synuclein dysregulation in astrocytes

Atmospheric particulate matter (PM) exacerbates the risk factor for Alzheimer's and Parkinson's diseases (PD) by promoting the alpha-synuclein (α-syn) pathology in the brain. However, the molecular mechanisms of astrocytes involvement in α-syn pathology underlying the process remain unclear. This study investigated PM with particle size <200 nm (PM0.2) exposure-induced α-syn pathology in ICR mice and primary astrocytes, then assessed the effects of mammalian target of rapamycin inhibitor (PP242) in vitro studies. We observed the α-syn pathology in the brains of exposed mice. Meanwhile, PM0.2-exposed mice also exhibited the activation of glial cell and the inhibition of autophagy. In vitro study, PM0.2 (3, 10 and 30 µg/mL) induced inflammatory response and the disorders of α-syn degradation in primary astrocytes, and lysosomal-associated membrane protein 2 (LAMP2)-mediated autophagy underlies α-syn pathology. The abnormal function of autophagy-lysosome was specifically manifested as the expression of microtubule-associated protein light chain 3 (LC3II), cathepsin B (CTSB) and lysosomal abundance increased first and then decreased, which might both be a compensatory mechanism to toxic α-syn accumulation induced by PM0.2. Moreover, with the transcription factor EB (TFEB) subcellular localization and the increase in LC3II, LAMP2, CTSB, and cathepsin D proteins were identified, leading to the restoration of the degradation of α-syn after the intervention of PP242. Our results identified that PM0.2 exposure could promote the α-syn pathological dysregulation in astrocytes, providing mechanistic insights into how PM0.2 increases the risk of developing PD and highlighting TFEB/LAMP2 as a promising therapeutic target for antagonizing PM0.2 toxicity.

Neuronal BAG3 attenuates tau hyperphosphorylation, synaptic dysfunction, and cognitive deficits induced by traumatic brain injury via the regulation of autophagy-lysosome pathway

Growing evidence supports that early- or middle-life traumatic brain injury (TBI) is a risk factor for developing Alzheimer's disease (AD) and AD-related dementia (ADRD). Nevertheless, the molecular mechanisms underlying TBI-induced AD-like pathology and cognitive deficits remain unclear. In this study, we found that a single TBI (induced by controlled cortical impact) reduced the expression of BCL2-associated athanogene 3 (BAG3) in neurons and oligodendrocytes, which is associated with decreased proteins related to the autophagy-lysosome pathway (ALP) and increased hyperphosphorylated tau (ptau) accumulation in excitatory neurons and oligodendrocytes, gliosis, synaptic dysfunction, and cognitive deficits in wild-type (WT) and human tau knock-in (hTKI) mice. These pathological changes were also found in human cases with a TBI history and exaggerated in human AD cases with TBI. The knockdown of BAG3 significantly inhibited autophagic flux, while overexpression of BAG3 significantly increased it in vitro. Specific overexpression of neuronal BAG3 in the hippocampus attenuated AD-like pathology and cognitive deficits induced by TBI in hTKI mice, which is associated with increased ALP-related proteins. Our data suggest that targeting neuronal BAG3 may be a therapeutic strategy for preventing or reducing AD-like pathology and cognitive deficits induced by TBI.

Alpha-synuclein, autophagy-lysosomal pathway, and Lewy bodies: Mutations, propagation, aggregation, and the formation of inclusions

Research into the pathophysiology of Parkinson's disease (PD) is a fast-paced pursuit, with new findings about PD and other synucleinopathies being made each year. The involvement of various lysosomal proteins, such as TFEB, TMEM175, GBA, and LAMP1/2, marks the rising awareness about the importance of lysosomes in PD and other neurodegenerative disorders. This, along with recent developments regarding the involvement of microglia and the immune system in neurodegenerative diseases, has brought about a new era in neurodegeneration: the role of proinflammatory cytokines on the nervous system, and their downstream effects on mitochondria, lysosomal degradation, and autophagy. More effort is needed to understand the interplay between neuroimmunology and disease mechanisms, as many of the mechanisms remain enigmatic. α-synuclein, a key protein in PD and the main component of Lewy bodies, sits at the nexus between lysosomal degradation, autophagy, cellular stress, neuroimmunology, PD pathophysiology, and disease progression. This review revisits some fundamental knowledge about PD while capturing some of the latest trends in PD research, specifically as it relates to α-synuclein.

Autophagy-lysosomal-associated neuronal death in neurodegenerative disease

Autophagy, the major lysosomal pathway for degrading damaged or obsolete constituents, protects neurons by eliminating toxic organelles and peptides, restoring nutrient and energy homeostasis, and inhibiting apoptosis. These functions are especially vital in neurons, which are postmitotic and must survive for many decades while confronting mounting challenges of cell aging. Autophagy failure, especially related to the declining lysosomal ("phagy") functions, heightens the neuron's vulnerability to genetic and environmental factors underlying Alzheimer's disease (AD) and other late-age onset neurodegenerative diseases. Components of the global autophagy-lysosomal pathway and the closely integrated endolysosomal system are increasingly implicated as primary targets of these disorders. In AD, an imbalance between heightened autophagy induction and diminished lysosomal function in highly vulnerable pyramidal neuron populations yields an intracellular lysosomal build-up of undegraded substrates, including APP-βCTF, an inhibitor of lysosomal acidification, and membrane-damaging Aβ peptide. In the most compromised of these neurons, β-amyloid accumulates intraneuronally in plaque-like aggregates that become extracellular senile plaques when these neurons die, reflecting an "inside-out" origin of amyloid plaques seen in human AD brain and in mouse models of AD pathology. In this review, the author describes the importance of lysosomal-dependent neuronal cell death in AD associated with uniquely extreme autophagy pathology (PANTHOS) which is described as triggered by lysosomal membrane permeability during the earliest "intraneuronal" stage of AD. Effectors of other cell death cascades, notably calcium-activated calpains and protein kinases, contribute to lysosomal injury that induces leakage of cathepsins and activation of additional death cascades. Subsequent events in AD, such as microglial invasion and neuroinflammation, induce further cytotoxicity. In major neurodegenerative disease models, neuronal death and ensuing neuropathologies are substantially remediable by reversing underlying primary lysosomal deficits, thus implicating lysosomal failure and autophagy dysfunction as primary triggers of lysosomal-dependent cell death and AD pathogenesis and as promising therapeutic targets.

Long Noncoding RNA NR_030777 Alleviates Cobalt Nanoparticles-Induced Neurodegenerative Damage by Promoting Autophagosome-Lysosome Fusion

Potential exposure to cobalt nanoparticles (CoNPs) occurs in various fields, including hard alloy industrial production, the increasing use of new energy lithium-ion batteries, and millions of patients with metal-on-metal joint prostheses. Evidence from human, animal, and in vitro experiments suggests a close relationship between CoNPs and neurotoxicity. However, a systematic assessment of central nervous system (CNS) impairment due to CoNPs exposure and the underlying molecular mechanisms is lacking. In this study, we found that CoNPs induced neurodegenerative damage both in vivo and in vitro, including cognitive impairment, β-amyloid deposition and Tau hyperphosphorylation. CoNPs promoted the formation of autophagosomes and impeding autophagosomal-lysosomal fusion in vivo and in vitro, leading to toxic protein accumulation. Moreover, CoNPs exposure reduced the level of transcription factor EB (TFEB) and the abundance of lysosome, causing a blockage in autophagosomal-lysosomal fusion. Interestingly, overexpression of long noncoding RNA NR_030777 mitigated CoNPs-induced neurodegenerative damage in both in vivo and in vitro models. Fluorescence in situ hybridization assay revealed that NR_030777 directly binds and stabilizes TFEB mRNA, alleviating the blockage of autophagosomal-lysosomal fusion and ultimately restoring neurodegeneration induced by CoNPs in vivo and in vitro. In summary, our study demonstrates that autophagic dysfunction is the main toxic mechanism of neurodegeneration upon CoNPs exposure and NR_030777 plays a crucial role in CoNPs-induced autophagic dysfunction. Additionally, the proposed adverse outcome pathway contributes to a better understanding of CNS toxicity assessment of CoNPs.

Tailoring the pKa of Fluorescence Lifetime Imaging Probes to Visualize Aggrephagy and Resolve Its Microenvironmental Viscosity

Aggrephagy describes lysosomal transport and degradation of protein aggregates via cellular macroautophagy, a key mechanism to prevent neurodegenerative diseases. Here, we develop a dual-probe method to visualize the aggrephagy process and resolve its viscosity heterogeneity using fluorescence lifetime imaging (FLIM). The dual-probe system consists of (1) a near-infrared lysosomal targeting FLIM probe (Lyso-P1) that is derived from a rhodamine scaffold with a tailored pKa value to accommodate an acidic lysosomal environment and (2) a green BODIPY-based FLIM probe (Agg-P2) that reports on degradation of cellular aggregates via HaloTag. Both probes exhibit acid-resistant, viscosity-dependent fluorescence intensity and lifetime (τ) responses, which are ready for intensity- and FLIM-based imaging. Photochemical, theoretical, and biochemical characterizations reveal the probes' mechanism-of-actions. In cells, we exploit Lyso-P1 and Agg-P2 to simultaneously quantify both lysosomal and protein aggegates' viscosity changes upon the aggrephagy process via FLIM. We reveal orthogonal changes in microenvironmental viscosities and morphological heterogeneity upon various cellular stresses. Overall, we provide an imaging toolset to quantitatively study aggrephay, which may benefit screening of aggrephay modulators for disease intervention.

Exploring the triad: VPS35, neurogenesis, and neurodegenerative diseases

Vacuolar protein sorting 35 (VPS35), a critical component of the retromer complex, plays a pivotal role in the pathogenesis of neurodegenerative diseases (NDs). It is involved in protein transmembrane sorting, facilitating the transport from endosomes to the trans-Golgi network (TGN) and plasma membrane. Recent investigations have compellingly associated mutations in the VPS35 gene with neurodegenerative disorders such as Parkinson's and Alzheimer's disease. These genetic alterations are implicated in protein misfolding, disrupted autophagic processes, mitochondrial dysregulation, and synaptic impairment. Furthermore, VPS35 exerts a notable impact on neurogenesis by influencing neuronal functionality, protein conveyance, and synaptic performance. Dysregulation or mutation of VPS35 may escalate the progression of neurodegenerative conditions, underscoring its pivotal role in safeguarding neuronal integrity. This review comprehensively discusses the role of VPS35 and its functional impairments in NDs. Furthermore, we provide an overview of the impact of VPS35 on neurogenesis and further explore the intricate relationship between neurogenesis and NDs. These research advancements offer novel perspectives and valuable insights for identifying potential therapeutic targets in the treatment of NDs.

HLH-30/TFEB modulates autophagy to improve proteostasis in Aβ transgenic Caenorhabditis elegans

Alzheimer's disease (AD) is a complex neurodegenerative disease that affects elderly individuals, characterized by senile plaques formed by extracellular amyloid beta (Aβ). Autophagy dysfunction is a manifestation of protein homeostasis imbalance in patients with AD, but its relationship with Aβ remains unclear. Here, we showed that in Aβ transgenic Caenorhabditis elegans, Aβ activated the TOR pathway and reduced the nuclear entry of HLH-30, leading to autophagy dysfunction characterized by autophagosome accumulation. Then, utilizing RNA-seq, we investigated the regulatory mechanisms by which HLH-30 modulates autophagy in C. elegans. We found that HLH-30 elevated the transcript levels of v-ATPase and cathepsin, thus enhancing lysosomal activity. This led to an increase in autophagic flux, facilitating more pronounced degradation of Aβ. Moreover, HLH-30 reduced the level of ROS induction by Aβ and enhanced the antioxidant stress capacity of the worms through the gsto-1 gene. Additionally, we identified two HLH-30/TFEB activators, saikosaponin B2 and hypericin, that improved autophagic flux, thereby enhancing protein homeostasis in C. elegans. Overall, our findings suggested that HLH-30/TFEB plays a key role in modulating autophagy and can be considered a promising drug target for AD treatments.

Premature senescence is regulated by crosstalk among TFEB, the autophagy lysosomal pathway and ROS derived from damaged mitochondria in NaAsO2-exposed auditory cells

Age-related hearing loss (ARHL) is one of the most prevalent types of sensory decline in a superaging society. Although various studies have focused on the effect of oxidative stress on the inner ear as an inducer of ARHL, there are no effective preventive approaches for ARHL. Recent studies have suggested that oxidative stress-induced DNA damage responses (oxidative DDRs) drive cochlear cell senescence and contribute to accelerated ARHL, and autophagy could function as a defense mechanism against cellular senescence in auditory cells. However, the underlying mechanism remains unclear. Sodium arsenite (NaAsO2) is a unique oxidative stress inducer associated with reactive oxygen species (ROS) that causes high-tone hearing loss similar to ARHL. Transcription factor EB (TFEB) functions as a master regulator of the autophagy‒lysosome pathway (ALP), which is a potential target during aging and the pathogenesis of various age-related diseases. Here, we focused on the function of TFEB and the impact of intracellular ROS as a potential target for ARHL treatment in a NaAsO2-induced auditory premature senescence model. Our results suggested that short exposure to NaAsO2 leads to DNA damage, lysosomal damage and mitochondrial damage in auditory cells, triggering temporary signals for TFEB transport into the nucleus and, as a result, causing insufficient autophagic flux and declines in lysosomal function and biogenesis and mitochondrial quality. Then, intracellular ROS derived from damaged mitochondria play a role as a second messenger to induce premature senescence in auditory cells. These findings suggest that TFEB activation via transport into the nucleus contributes to anti-senescence activity in auditory cells and represents a new therapeutic target for ARHL. We have revealed the potential function of TFEB as a master regulator of the induction of oxidative stress-induced premature senescence and the senescence-associated secretion phenotype (SASP) in auditory cells, which regulates ALP and controls mitochondrial quality through ROS production.

Yin-Yang: two sides of extracellular vesicles in inflammatory diseases

The concept of Yin-Yang, originating in ancient Chinese philosophy, symbolizes two opposing but complementary forces or principles found in all aspects of life. This concept can be quite fitting in the context of extracellular vehicles (EVs) and inflammatory diseases. Over the past decades, numerous studies have revealed that EVs can exhibit dual sides, acting as both pro- and anti-inflammatory agents, akin to the concept of Yin-Yang theory (i.e., two sides of a coin). This has enabled EVs to serve as potential indicators of pathogenesis or be manipulated for therapeutic purposes by influencing immune and inflammatory pathways. This review delves into the recent advances in understanding the Yin-Yang sides of EVs and their regulation in specific inflammatory diseases. We shed light on the current prospects of engineering EVs for treating inflammatory conditions. The Yin-Yang principle of EVs bestows upon them great potential as, therapeutic, and preventive agents for inflammatory diseases.

Iron Dyshomeostasis in Neurodegeneration with Brain Iron Accumulation (NBIA): Is It the Cause or the Effect?

Iron is an essential metal ion implicated in several cellular processes. However, the reactive nature of iron renders this metal ion potentially dangerous for cells, and its levels need to be tightly controlled. Alterations in the intracellular concentration of iron are associated with different neuropathological conditions, including neurodegeneration with brain iron accumulation (NBIA). As the name suggests, NBIA encompasses a class of rare and still poorly investigated neurodegenerative disorders characterized by an abnormal accumulation of iron in the brain. NBIA is mostly a genetic pathology, and to date, 10 genes have been linked to familial forms of NBIA. In the present review, after the description of the principal mechanisms implicated in iron homeostasis, we summarize the research data concerning the pathological mechanisms underlying the genetic forms of NBIA and discuss the potential involvement of iron in such processes. The picture that emerges is that, while iron overload can contribute to the pathogenesis of NBIA, it does not seem to be the causal factor in most forms of the pathology. The onset of these pathologies is rather caused by a combination of processes involving the interplay between lipid metabolism, mitochondrial functions, and autophagic activity, eventually leading to iron dyshomeostasis.

PDCD4 triggers α-synuclein accumulation and motor deficits via co-suppressing TFE3 and TFEB translation in a model of Parkinson's disease

TFE3 and TFEB, as the master regulators of lysosome biogenesis and autophagy, are well characterized to enhance the synaptic protein α-synuclein degradation in protecting against Parkinson's disease (PD) and their levels are significantly decreased in the brain of PD patients. However, how TFE3 and TFEB are regulated during PD pathogenesis remains largely vague. Herein, we identified that programmed cell death 4 (PDCD4) promoted pathologic α-synuclein accumulation to facilitate PD development via suppressing both TFE3 and TFEB translation. Conversely, PDCD4 deficiency significantly augmented global and nuclear TFE3 and TFEB distributions to alleviate neurodegeneration in a mouse model of PD with overexpressing α-synuclein in the striatum. Mechanistically, like TFEB as we reported before, PDCD4 also suppressed TFE3 translation, rather than influencing its transcription and protein stability, to restrain its nuclear translocation and lysosomal functions, eventually leading to α-synuclein aggregation. We proved that the two MA3 domains of PDCD4 mediated the translational suppression of TFE3 through binding to its 5'-UTR of mRNA in an eIF-4A dependent manner. Based on this, we developed a blood-brain barrier penetrating RVG polypeptide modified small RNA drug against pdcd4 to efficiently prevent α-synuclein neurodegeneration in improving PD symptoms by intraperitoneal injections. Together, we suggest PDCD4 as a PD-risk protein to facilitate α-synuclein neurodegeneration via suppressing TFE3 and TFEB translation and further provide a potential small RNA drug against pdcd4 to treat PD by intraperitoneal injections.

Design and validation of a reporter mouse to study the dynamic regulation of TFEB and TFE3 activity through in vivo imaging techniques

TFEB and TFE3 belong to the MiT/TFE family of transcription factors that bind identical DNA responsive elements in the regulatory regions of target genes. They are involved in regulating lysosomal biogenesis, function, exocytosis, autophagy, and lipid catabolism. Precise control of TFEB and TFE3 activity is crucial for processes such as senescence, stress response, energy metabolism, and cellular catabolism. Dysregulation of these factors is implicated in various diseases, thus researchers have explored pharmacological approaches to modulate MiT/TFE activity, considering these transcription factors as potential therapeutic targets. However, the physiological complexity of their functions and the lack of suitable in vivo tools have limited the development of selective MiT/TFE modulating agents. Here, we have created a reporter-based biosensor, named CLEARoptimized, facilitating the pharmacological profiling of TFEB- and TFE3-mediated transcription. This innovative tool enables the measurement of TFEB and TFE3 activity in living cells and mice through imaging and biochemical techniques. CLEARoptimized consists of a promoter with six coordinated lysosomal expression and regulation motifs identified through an in-depth bioinformatic analysis of the promoters of 128 TFEB-target genes. The biosensor drives the expression of luciferase and tdTomato reporter genes, allowing the quantification of TFEB and TFE3 activity in cells and in animals through optical imaging and biochemical assays. The biosensor's validity was confirmed by modulating MiT/TFE activity in both cell culture and reporter mice using physiological and pharmacological stimuli. Overall, this study introduces an innovative tool for studying autophagy and lysosomal pathway modulation at various biological levels, from individual cells to the entire organism.Abbreviations: CLEAR: coordinated lysosomal expression and regulation; MAR: matrix attachment regions; MiT: microphthalmia-associated transcription factor; ROI: region of interest; TBS: tris-buffered saline; TF: transcription factor; TFE3: transcription factor binding to IGHM enhancer 3; TFEB: transcription factor EB; TH: tyrosine hydroxylase; TK: thymidine kinase; TSS: transcription start site.

Endosome-microautophagy targeting chimera (eMIATAC) for targeted proteins degradation and enhance CAR-T cell anti-tumor therapy

Rationale: Since oncogene expression products often exhibit upregulation or abnormally activated activity, developing a technique to regulate abnormal protein levels represent a viable approach for treating tumors and protein abnormality-related diseases. Methods: We first screened out eMIATAC components with high targeted degradation efficiency and explored the mechanism by which eMIATAC induced target protein degradation, and verified the degradation efficiency of the target protein by protein imprinting and flow cytometry. Next, we recombined eMIATAC with some controllable elements to verify the regulatable degradation performance of the target protein. Subsequently, we constructed eMIATAC that can express targeted degradation of AKT1 and verified its effect on GBM cell development in vitro and in vivo. Finally, we concatenated eMIATAC with CAR sequences to construct CAR-T cells with low BATF protein levels and verified the changes in their anti-tumor efficacy. Results: we developed a system based on the endosome-microautophagy-lysosome pathway for degrading endogenous proteins: endosome-MicroAutophagy TArgeting Chimera (eMIATAC), dependent on Vps4A instead of lysosomal-associated membrane protein 2A (LAMP2A) to bind to the chaperone Hsc70 and the protein of interest (POI). The complex was then transported to the lysosome by late endosomes, where degradation occurred similarly to microautophagy. The eMIATACs demonstrated accuracy, efficiency, reversibility, and controllability in degrading the target protein EGFP. Moreover, eMIATAC exhibited excellent performance in knocking down POI when targeting endogenous proteins in vivo and in vitro. Conclusions: The eMIATACs could not only directly knock down abnormal proteins for glioma treatment but also enhance the therapeutic effect of CAR-T cell therapy for tumors by knocking down T cell exhaustion-related proteins. The newly developed eMIATAC system holds promise as a novel tool for protein knockdown strategies. By enabling direct control over endogenous protein levels, eMIATAC has the potential to revolutionize treatment for cancer and genetic diseases.

Uric Acid Mitigates Cognitive Deficits via TFEB-Mediated Microglial Autophagy in Mice Models of Alzheimer's Disease

Clinical trials have demonstrated the potential neuroprotective effects of uric acid (UA) in Alzheimer's disease (AD). However, the specific mechanism underlying the neuroprotective effect of UA remains unclear. In the present study, we investigated the neuroprotective effect and underlying mechanism of UA in AD mouse models. Various behavioral tests including an elevated plus maze, Barnes maze, and Morris water maze were conducted to evaluate the impact of UA on cognitive function in β-amyloid (Aβ) microinjection and APP23/PS45 double transgenic mice models of AD. Immunohistochemical staining was employed to visualize pathological changes in the brains of AD model mice. Western blotting and immunofluorescence techniques were used to assess levels of autophagy-related proteins and transcription factor EB (TFEB)-related signaling pathways. BV2 cells were used to investigate the association between UA and microglial autophagy. We reported that UA treatment significantly alleviated memory decline in Aβ-induced AD model mice and APP23/PS45 double transgenic AD model mice. Furthermore, UA activated microglia and upregulated the autophagy-related proteins such as LC3II/I ratio, Beclin-1, and LAMP1 in the hippocampus of AD model mice. Similarly, UA protected BV2 cells from Aβ toxicity by upregulating the expressions of Beclin-1, LAMP1, and the LC3II/I ratio, whereas genetic inhibition of TFEB completely abolished these protective effects. Our results indicate that UA may serve as a novel activator of TFEB to induce microglia autophagy and facilitate Aβ degradation, thereby improving cognitive function in AD model mice. Therefore, these findings suggest that UA may be a novel therapeutic agent for AD treatment.

Mitochondria-lysosome-extracellular vesicles axis and nanotheranostics in neurodegenerative diseases

The intricate functional interactions between mitochondria and lysosomes play a pivotal role in maintaining cellular homeostasis and proper cellular functions. This dynamic interplay involves the exchange of molecules and signaling, impacting cellular metabolism, mitophagy, organellar dynamics, and cellular responses to stress. Dysregulation of these processes has been implicated in various neurodegenerative diseases. Additionally, mitochondrial-lysosomal crosstalk regulates the exosome release in neurons and glial cells. Under stress conditions, neurons and glial cells exhibit mitochondrial dysfunction and a fragmented network, which further leads to lysosomal dysfunction, thereby inhibiting autophagic flux and enhancing exosome release. This comprehensive review synthesizes current knowledge on mitochondrial regulation of cell death, organelle dynamics, and vesicle trafficking, emphasizing their significant contributions to neurodegenerative diseases. Furthermore, we explore the emerging field of nanomedicine in the management of neurodegenerative diseases. The review provides readers with an insightful overview of nano strategies that are currently advancing the mitochondrial-lysosome-extracellular vesicle axis as a therapeutic approach for mitigating neurodegenerative diseases.

Cathelicidin LL-37 promotes wound healing in diabetic mice by regulating TFEB-dependent autophagy

Diabetic patients often experience impaired wound healing. Human cathelicidin LL-37 possesses various biological functions, such as anti-microbial, anti-inflammatory, and pro-wound healing activities. Autophagy has important effects on skin wound healing. However, little is known about whether LL-37 accelerates diabetic wound healing by regulating autophagy. In the study, we aimed to investigate the role of autophagy in LL-37-induced wound healing and uncover the underlying mechanisms involved. A full-thickness wound closure model was established in diabetic mice to evaluate the effects of LL-37 and an autophagy inhibitor (3-MA) on wound healing. The roles of LL-37 and 3-MA in regulating keratinocyte migration were assessed using transwell migration and wound healing assays. The activation of transcription factor EB (TFEB) was measured using western blotting and immunofluorescence (IF) assays of its nuclear translocation. The results showed that LL-37 treatment improved wound healing in diabetic mice, whereas these effects were reversed by 3-MA. In vitro, 3-MA decreased the effects of LL-37 on promoting HaCat keratinocyte migration in the presence of high glucose (HG). Mechanistically, LL-37 promoted TFEB activation and resulted in subsequent activation of autophagy, as evidenced by increased nuclear translocation of TFEB and increased expression of ATG5, ATG7, and beclin 1 (BECN1), whereas these changes were blocked by TFEB knockdown. As expected, TFEB knockdown damaged the effects of LL-37 on promoting keratinocyte migration. Collectively, these results suggest that LL-37 accelerates wound healing in diabetic mice by activating TFEB-dependent autophagy, providing new insights into the mechanism by which LL-37 promotes diabetic wound healing.

Simultaneously Monitoring Multiple Autophagic Processes and Assessing Autophagic Flux in Single Cells by In Situ Fluorescence Cross-Correlation Spectroscopy

Autophagy is a widely conserved and multistep cellular catabolic process and maintains cellular homeostasis and normal cellular functions via the degradation of some harmful intracellular components. It was reported that high basal autophagic activity may be closely related to tumorigenesis. So far, the fluorescence imaging technique has been widely used to study autophagic processes, but this method is only suitable for distinguishing autophagosomes and autolysosomes. Simultaneously monitoring multiple autophagic processes remains a significant challenge due to the lack of an efficient detection method. Here, we demonstrated a new method for simultaneously monitoring multiple autophagic processes and assessing autophagic flux in single cells based on in situ fluorescence cross-correlation spectroscopy (FCCS). In this study, microtubule-associated protein 1A/1B-light chain 3B (LC3B) was fused with two tandem fluorescent proteins [mCherry red fluorescent protein (mCherry) and enhanced green fluorescent protein (EGFP)] to achieve the simultaneous labeling and distinguishing of multiple autophagic structures based on the differences in characteristic diffusion time (τD). Furthermore, we proposed a new parameter "delivery efficiency of autophagosome (DEAP)" to assess autophagic flux based on the cross correlation (CC) value. Our results demonstrate that FCCS can efficiently distinguish three autophagic structures, assess the induced autophagic flux, and discriminate different autophagy regulators. Compared with the commonly used fluorescence imaging technique, the resolution of FCCS remains unaffected by Brownian motion and fluorescent monomers in the cytoplasm and is well suitable to distinguishing differently colored autophagic structures and monitoring autophagy.

Subchondral osteoclasts and osteoarthritis: new insights and potential therapeutic avenues

Osteoarthritis (OA) is the most common joint disease, and good therapeutic results are often difficult to obtain due to its complex pathogenesis and diverse causative factors. After decades of research and exploration of OA, it has been progressively found that subchondral bone is essential for its pathogenesis, and pathological changes in subchondral bone can be observed even before cartilage lesions develop. Osteoclasts, the main cells regulating bone resorption, play a crucial role in the pathogenesis of subchondral bone. Subchondral osteoclasts regulate the homeostasis of subchondral bone through the secretion of degradative enzymes, immunomodulation, and cell signaling pathways. In OA, osteoclasts are overactivated by autophagy, ncRNAs, and Rankl/Rank/OPG signaling pathways. Excessive bone resorption disrupts the balance of bone remodeling, leading to increased subchondral bone loss, decreased bone mineral density and consequent structural damage to articular cartilage and joint pain. With increased understanding of bone biology and targeted therapies, researchers have found that the activity and function of subchondral osteoclasts are affected by multiple pathways. In this review, we summarize the roles and mechanisms of subchondral osteoclasts in OA, enumerate the latest advances in subchondral osteoclast-targeted therapy for OA, and look forward to the future trends of subchondral osteoclast-targeted therapies in clinical applications to fill the gaps in the current knowledge of OA treatment and to develop new therapeutic strategies.

Transcription Factor EB Overexpression through Glial Fibrillary Acidic Protein Promoter Disrupts Neuronal Lamination by Dysregulating Neurogenesis during Embryonic Development

INTRODUCTION

Transcription factor EB (TFEB), a key regulator of autophagy and lysosomal biogenesis, has diverse roles in various physiological processes. Enhancing lysosomal function by TFEB activation has recently been implicated in restoring neural stem cell (NSC) function. Overexpression of TFEB can inhibit the cell cycle of newborn cortical NSCs. It has also been found that TFEB regulates the pluripotency transcriptional network in mouse embryonic stem cells independent of autophagy and lysosomal biogenesis. This study aims to explore the effects of TFEB activation on neurogenesis in vivo through transgenic mice.

METHODS

We developed a glial fibrillary acidic protein (GFAP)-driven TFEB overexpression mouse model (TFEB GoE) by crossing the floxed TFEB overexpression mice and hGFAP-Cre mice. We performed immunohistochemical and fluorescence staining on brain tissue from newborn mice to assess neurogenesis changes, employing markers such as GFAP, Nestin, Ki67, doublecortin (DCX), Tbr1, and NeuN to trace different stages of neural development and cell proliferation.

RESULTS

TFEB GoE mice exhibited premature mortality, dying 10-20 days after birth. Immunohistochemical analysis revealed significant abnormalities, including disrupted hippocampal structure and cortical layering. Compared to control mice, TFEB GoE mice showed a marked increase in radial glial cells (RGCs) in the hippocampus and cortex, with Ki67 staining indicating these cells were predominantly in a quiescent state. This suggests that TFEB overexpression suppresses RGC proliferation. Additionally, abnormal distributions of migrating neurons and mature neurons were observed, highlighted by DCX, Tbr1, and NeuN staining, indicating a disruption in normal neurogenesis.

CONCLUSION

This study, using transgenic animals in vivo, revealed that GFAP-driven TFEB overexpression leads to abnormal neural layering in the hippocampus and cortex by dysregulating neurogenesis. Our study is the first to discover the detrimental impact of TFEB overexpression on neurogenesis during embryonic development, which has important reference significance for future TFEB overexpression interventions in NSCs for treatment.

INTRODUCTION

Transcription factor EB (TFEB), a key regulator of autophagy and lysosomal biogenesis, has diverse roles in various physiological processes. Enhancing lysosomal function by TFEB activation has recently been implicated in restoring neural stem cell (NSC) function. Overexpression of TFEB can inhibit the cell cycle of newborn cortical NSCs. It has also been found that TFEB regulates the pluripotency transcriptional network in mouse embryonic stem cells independent of autophagy and lysosomal biogenesis. This study aims to explore the effects of TFEB activation on neurogenesis in vivo through transgenic mice.

METHODS

We developed a glial fibrillary acidic protein (GFAP)-driven TFEB overexpression mouse model (TFEB GoE) by crossing the floxed TFEB overexpression mice and hGFAP-Cre mice. We performed immunohistochemical and fluorescence staining on brain tissue from newborn mice to assess neurogenesis changes, employing markers such as GFAP, Nestin, Ki67, doublecortin (DCX), Tbr1, and NeuN to trace different stages of neural development and cell proliferation.

RESULTS

TFEB GoE mice exhibited premature mortality, dying 10-20 days after birth. Immunohistochemical analysis revealed significant abnormalities, including disrupted hippocampal structure and cortical layering. Compared to control mice, TFEB GoE mice showed a marked increase in radial glial cells (RGCs) in the hippocampus and cortex, with Ki67 staining indicating these cells were predominantly in a quiescent state. This suggests that TFEB overexpression suppresses RGC proliferation. Additionally, abnormal distributions of migrating neurons and mature neurons were observed, highlighted by DCX, Tbr1, and NeuN staining, indicating a disruption in normal neurogenesis.

CONCLUSION

This study, using transgenic animals in vivo, revealed that GFAP-driven TFEB overexpression leads to abnormal neural layering in the hippocampus and cortex by dysregulating neurogenesis. Our study is the first to discover the detrimental impact of TFEB overexpression on neurogenesis during embryonic development, which has important reference significance for future TFEB overexpression interventions in NSCs for treatment.

Altered lipid homeostasis is associated with cerebellar neurodegeneration in SNX14 deficiency

Dysregulated lipid homeostasis is emerging as a potential cause of neurodegenerative disorders. However, evidence of errors in lipid homeostasis as a pathogenic mechanism of neurodegeneration remains limited. Here, we show that cerebellar neurodegeneration caused by Sorting Nexin 14 (SNX14) deficiency is associated with lipid homeostasis defects. Recent studies indicate that SNX14 is an interorganelle lipid transfer protein that regulates lipid transport, lipid droplet (LD) biogenesis, and fatty acid desaturation, suggesting that human SNX14 deficiency belongs to an expanding class of cerebellar neurodegenerative disorders caused by altered cellular lipid homeostasis. To test this hypothesis, we generated a mouse model that recapitulates human SNX14 deficiency at a genetic and phenotypic level. We demonstrate that cerebellar Purkinje cells (PCs) are selectively vulnerable to SNX14 deficiency while forebrain regions preserve their neuronal content. Ultrastructure and lipidomic studies reveal widespread lipid storage and metabolism defects in SNX14-deficient mice. However, predegenerating SNX14-deficient cerebella show a unique accumulation of acylcarnitines and depletion of triglycerides. Furthermore, defects in LD content and telolysosome enlargement in predegenerating PCs suggest lipotoxicity as a pathogenic mechanism of SNX14 deficiency. Our work shows a selective cerebellar vulnerability to altered lipid homeostasis and provides a mouse model for future therapeutic studies.