bims-auttor 2026-01-11 papers

bims-auttor

Biomed News

on Autophagy and mTOR

Issue of 2026–01–11
thirty-one papers selected by
Viktor Korolchuk, Newcastle University

Autophagy-Lysosome Pathway Dysfunction in Neurodegeneration and Cancer: Mechanisms and Therapeutic Opportunities.
Proteasome inhibition by VR23 enhances autophagic clearance of FUSP525L-mediated persistent stress granule in SH-SY5Y cells.
TBK1 orchestrates autophagy and endo-lysosomal pathways in human neurons.
A Rab1 interactome illuminates a dual role in autophagy and membrane trafficking.
Loss of TMEM55B modulates lipid metabolism through dysregulated lipophagy and mitochondrial function.
Integrated Interactome and Phosphoproteome Analysis Reveals Novel MAP4K3-Regulated Pathways and Unexpected Cellular Roles for MAP4K3.
Selective autophagy fine-tunes Stat92E activity by degrading Su(var)2-10/PIAS in Drosophila glia.
Rapid activation of p62 body-mediated autophagy in human cells under hyperosmotic stress.
The Mechanistic Target of Rapamycin (mTOR) Pathway as a Target of Anti-aging Therapies: The Role of Rapamycin and Its Analogs in the Regulation of Cellular Processes and Their Impact on Longevity.
Proteasomal Degradation of Mutant Huntingtin Exon1 Regulates Autophagy.
Structure of the lysosomal KICSTOR-GATOR1-SAMTOR nutrient-sensing supercomplex.
CASTOR1 and CASTOR2 respond to different arginine levels to regulate mTORC1 activity.
Mitophagy in the pathogenesis and management of disease.
Calcium overload induced mitochondrial and lysosomal dysfunction is regulated by Tousled-like kinase in a-synucleinopathy.
HMGA2 inhibits Pink1-mediated mitophagy and promotes vascular calcification.
Measuring lysosome damage and lysophagy in vivo.
Spatial Regulation of Lysosomal Vesicle Acidification Along the Axon via mRAVE-Dependent v-ATPase Assembly.
A TGF-β1/LEF1/β-catenin/JLP network motif regulates autophagy and tubule injury in renal fibrosis.
Superoxide signals for the mitophagy of dysfunctional mitochondria to maintain quality control.
LncRNA SNHG1 Knockdown Ameliorates HIV-1 gp120V3 Loop-Induced Microglial Neuroinflammation by Regulating the Autophagy Process.
Ubiquitination and autophagy in host-pathogen interactions: from immune surveillance to therapeutic targeting.
Plasma membrane-to-lysosome FGR signaling regulates endocytosis-associated lysosome homeostasis.
The ATG8 E3-like ligases sense lysosomal damage and initiate ESCRT-mediated membrane repair.
Targeting Fibrosis: ALA-PDT Triggers PINK1/Parkin-Dependent Mitophagy and Apoptosis in Fibroblasts.
Regulation of the Rheb GTPase via GATOR1 Complex.
The many faces of p97/Cdc48 in mitochondrial homeostasis.
Inhibition of Annexin A2 Facilitates PHB2-Mediated Mitophagy in Cardiomyocytes to Alleviate Cardiac Injury and Remodeling After Infarction.
USP25 inhibition ameliorates Parkinson's disease by restoring mitophagy.
Astrocytic TPK1 mitigates amyloid pathology via TFEB-mediated endocytosis.
Rsp5/NEDD4 and ESCRT regulate TDP-43 toxicity and turnover via an endolysosomal clearance mechanism.
Dynamins maintain nuclear envelope homeostasis and genome stability.

Int J Mol Sci. 2025 Dec 29. pii: 366. [Epub ahead of print]27(1):

Autophagy-Lysosome Pathway Dysfunction in Neurodegeneration and Cancer: Mechanisms and Therapeutic Opportunities.

Mingyang Du, Yang Yu, Jiachang Wang, Cuicui Ji.

  The autophagy-lysosome system is a master regulator of cellular homeostasis, integrating quality control, metabolism, and cell fate through the selective degradation of cytoplasmic components. Disruption of either autophagic flux or lysosomal function compromises this degradative pathway and leads to diverse pathological conditions. Emerging evidence identifies the autophagy-lysosome network as a central signaling hub that connects metabolic balance to disease progression, particularly in neurodegenerative disorders and cancer. Although cancer and neurodegenerative diseases exhibit seemingly opposite outcomes-uncontrolled proliferation versus progressive neuronal loss-both share common mechanistic foundations within the autophagy-lysosome axis. Here, we synthesize recent advances on the roles of autophagy and lysosomal mechanisms in neurodegenerative diseases and cancer, especially on how defects in lysosomal acidification, membrane integrity, and autophagosome-lysosome fusion contribute to toxic protein accumulation and organelle damage in Alzheimer's and Parkinson's diseases, while the same machinery is repurposed by tumor cells to sustain anabolic growth, stress tolerance, and therapy resistance. We also highlight emerging lysosome-centered therapeutic approaches, including small molecules that induce lysosomal membrane permeabilization, nanomedicine-based pH correction, and next-generation protein degradation technologies. Finally, we discuss the major challenges and future opportunities for translating these mechanistic insights into clinical interventions.

Keywords:  autophagy; cancer; lysosome; neurodegenerative disease

DOI:  https://doi.org/10.3390/ijms27010366
Mol Brain. 2026 Jan 08.

Proteasome inhibition by VR23 enhances autophagic clearance of FUSP525L-mediated persistent stress granule in SH-SY5Y cells.

Seong Hyun Kim, Jun Hee So, Yong Hwan Kim, Hyo-Sung Kim, Na Yeon Park, Joon Bum Kim, Doo Sin Jo, Eunbyul Yeom, Jin-A Lee, Ji-Eun Bae, Dong-Hyung Cho.

  Autophagy is a conserved catabolic pathway that preserves cellular homeostasis through lysosomal degradation. Beyond its general role in proteostasis, selective autophagy mediates the clearance of selective cellular targets such as persistent stress granules (SGs), in a process termed granulophagy. SGs are dynamic cytoplasmic assemblies that normally disassemble after stress relief; however, their aberrant persistence has arisen as a pathological feature of neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). However, the molecular regulation of granulophagy remains incompletely understood. Here, we established a tandem fluorescent SG reporter system with mCherry-pHluorin-FUSP525L, enabling live-cell visualization of granulophagic flux. Using this system, we screened a chemical library and identified VR23, a proteasome inhibitor, as a potent inducer of granulophagy. VR23 promoted SG clearance through autophagic mechanisms, as evidenced by enhanced LC3 colocalization, lysosome-dependent degradation, and Bafilomycin A1-sensitive flux. Notably, disruption of SG assembly via G3BP1 inhibition abolished VR23-induced clearance, confirming its SG selectivity. These findings suggest a link between proteasome inhibition and granulophagy, highlighting VR23 as a valuable tool compound to dissect the mechanisms of SG turnover, and provide a platform for discovering modulators of pathological SG clearance in protein aggregation.

Keywords:  FUS; Granulophagy; Selective autophagy; Stress granules; VR23

DOI:  https://doi.org/10.1186/s13041-025-01273-z
Autophagy. 2026 Jan 04. 1-3

TBK1 orchestrates autophagy and endo-lysosomal pathways in human neurons.

Daniel A Mordes, Julie Smeyers.

  Haploinsufficiency of TBK1 causes familial ALS and frontotemporal dementia (FTD), yet the mechanisms by which TBK1 loss leads to neurodegeneration remain unclear. Using deep proteomics and phospho-proteomics, we demonstrate that TBK1 regulates select macroautophagy/autophagy factors, targeting cargo receptors and autophagy initiation factors, and also sustains the phosphorylation of the late endosomal marker RAB7A in stem cells and stem cell-derived excitatory neurons. We further uncovered novel TBK1-dependent phosphorylation sites in the key autophagy protein SQSTM1/p62. Loss of TBK1 function results in a cell-autonomous neurodegenerative phenotype characterized by impaired neurite outgrowth and lysosomal dysfunction.

Keywords:  TBK1; lysosomes; neurodegeneration; proteomics; selective autophagy

DOI:  https://doi.org/10.1080/15548627.2025.2609924
J Cell Biol. 2026 Mar 02. pii: e202507084. [Epub ahead of print]225(3):

A Rab1 interactome illuminates a dual role in autophagy and membrane trafficking.

Alexander R van Vliet, Alison K Gillingham, Tomos E Morgan, Yohei Ohashi, Tom S Smith, Ferdos Abid Ali, Sean Munro.

The small GTPase Rab1 is found in all eukaryotes and acts in both ER-to-Golgi transport and autophagy. Several Rab1 effectors and regulators have been identified, but the mechanisms by which Rab1 orchestrates these distinct processes remain incompletely understood. We apply MitoID, a proximity biotinylation approach, to expand the interactome of human Rab1A and Rab1B. We identify new interactors among known membrane traffic and autophagy machinery, as well as previously uncharacterized proteins. One striking set of interactors are the cargo receptors for selective autophagy, indicating a broader role for Rab1 in autophagy than previously supposed. Two cargo receptor interactions are validated in vitro, with the Rab1-binding site in optineurin being required for mitophagy in vivo. We also find an interaction between Rab1 and the dynein adaptor FHIP2A that can only be detected in the presence of membranes. This explains the recruitment of dynein to the ER-Golgi intermediate compartment and demonstrates that conventional methods can miss a subset of effectors of small GTPases.

DOI: https://doi.org/10.1083/jcb.202507084
Cell Death Dis. 2026 Jan 09. 17(1): 26

Loss of TMEM55B modulates lipid metabolism through dysregulated lipophagy and mitochondrial function.

Yuanyuan Qin, Sheila S Teker, Nilsa La Cunza, Yao Tong, Elizabeth Theusch, Neil V Yang, Leela Venkatesan, Julia Su, Xuanwen Wang, Ronald M Krauss, Aparna Lakkaraju, Aras N Mattis, Marisa W Medina.

Lipophagy is a form of selective autophagy that targets the lipid droplets for lysosomal decay and has been implicated in the onset and progression of metabolic dysfunction-associated steatotic liver disease (MASLD). Factors that augment lipophagy have been identified as targets for MASLD therapeutic development. TMEM55B is a key regulator of lysosomal positioning, which is critical for lysosome fusion with the autophagosome, but is less well studied. Here, we demonstrate that the absence of TMEM55B in murine models accelerates MASLD onset and progression to metabolic dysfunction-associated steatohepatitis (MASH). In cellular models, TMEM55B deficiency enhances incomplete lipophagy, whereby lysosome-lipid droplet interactions are increased, but lysosomal cargo is not fully degraded and/or released, leading to the development of lipid-filled lysosomes (lipolysosomes). Loss of TMEM55B also impairs mitophagy, causing an accumulation of dysfunctional mitochondria. This imbalance leads to increased lipid accumulation and oxidative stress, worsening MASLD. These findings underscore the importance of lysosomal positioning in lipid metabolism and suggest that targeting lipophagy for MASLD therapeutic development should be carefully considered to ensure promotion of the entire lipophagic flux pathway and whether it occurs in the context of mitochondrial dysfunction.

DOI: https://doi.org/10.1038/s41419-025-08210-x
FASEB J. 2026 Jan 15. 40(1): e71415

Integrated Interactome and Phosphoproteome Analysis Reveals Novel MAP4K3-Regulated Pathways and Unexpected Cellular Roles for MAP4K3.

Mary Rose Branch, Byeonggu Cha, Luke C Bartelt, Wen-Chuan Shen, Albert R La Spada.

  MAP4K3, also known as germinal-center kinase-like kinase (GLK), is a member of the Ste20 sub-family of MAPKs. Numerous studies have shown that MAP4K3 is required for mTORC1 activation in response to amino acids, and MAP4K3 represses autophagy by initiating inhibitory suppression of transcription factor EB. Furthermore, MAP4K3 is ubiquitously expressed; thus, MAP4K3 likely plays a central role in regulating the metabolic disposition of the cell. To define the basis for MAP4K3 regulation of these cellular pathways and to identify novel cellular processes subject to MAP4K3 regulation, we performed mass spectrometry interactome analysis of MAP4K3 and unbiased phosphoproteomics to define the MAP4K3 phosphoproteome landscape. MAP4K3 interactome and phosphoproteome analysis confirmed the existence of numerous MAP4K3 interactors and substrates involved in mTORC1 regulation, while suggesting a potential role for MAP4K3 in controlling the subcellular localization of mTORC1 via phosphorylation of Mios, a component of the GATOR2 complex. In addition to linking MAP4K3 to processes occurring at the lysosome, MAP4K3 interactome and phosphoproteome data revealed an unexpected role for MAP4K3 in the nucleus, implicating MAP4K3 in DNA damage response and repair. When we examined MAP4K3 subcellular localization, we confirmed that MAP4K3 is present in the nucleus, and found that MAP4K3 interacts with the DNA damage response regulator PARP1. Our unbiased interactome and phosphoproteome analysis of MAP4K3 provides a powerful resource for further study of MAP4K3 function in the mTORC1 pathway, but also in the regulation of DNA damage response and repair pathways in the nucleus.

Keywords:  DNA repair; MAP kinase kinase kinase kinase 3 (MAP4K3); interactome; lysosome; mechanistic target of rapamycin complex 1 (mTORC1); nucleus; phosphoproteomics; proteomics

DOI:  https://doi.org/10.1096/fj.202501003R
Life Sci Alliance. 2026 Mar;pii: e202503375. [Epub ahead of print]9(3):

Selective autophagy fine-tunes Stat92E activity by degrading Su(var)2-10/PIAS in Drosophila glia.

Virág Vincze, Zsombor Esküdt, Erzsébet Fehér-Juhász, Aishwarya Sanjay Chhatre, András Jipa, Anna Rita Galambos, Dalma Feil-Börcsök, Melinda Bence, Gábor Juhász, Áron Szabó.

Glial immunity plays a pivotal role in the maintenance of nervous system homeostasis and in responses to stress conditions, including neural injuries. The transcription factor Stat92E is activated independently of the canonical JAK/STAT pathway in Drosophila glial cells after brain injury to shape glial reactivity toward degenerating axons. However, the upstream regulatory mechanisms governing Stat92E activation remain elusive. Here, we reveal that selective autophagy gates nuclear translocation of Stat92E after injury and directs the degradation of the PIAS SUMO ligase family member Stat92E repressor, Su(var)2-10, in glia. Autophagic elimination of Su(var)2-10 mediated by its colocalization and interaction with the core autophagy factor Atg8a is required for efficient Stat92E-dependent transcription after injury. In line with this, we demonstrate that autophagy is essential for the up-regulation of an innate immune pathway in glial cells after axon injury, characterized by the induction of virus-induced RNA 1 (vir-1). We propose that autophagic Su(var)2-10 breakdown controls Stat92E activation to allow glial reactivity. These findings identify a critical role of autophagy in glial immunity as part of nervous system injury responses.

DOI: https://doi.org/10.26508/lsa.202503375
Commun Biol. 2026 Jan 05. 9(1): 1

Rapid activation of p62 body-mediated autophagy in human cells under hyperosmotic stress.

Naoki Tamura, Satoshi Waguri.

The autophagy receptor p62 is degraded via autophagy under hyperosmotic stress, but whether this involves the formation of biomolecular condensates (p62 bodies) remains unclear. Using human cells, we found that p62 bodies formed within 1 minute of hyperosmotic stress, and increased with stress severity. They formed faster and under milder stress than stress granules, a classic condensate, and exhibited liquid-like properties. Unlike stress granules, p62 bodies frequently colocalized with LC3 and WIPI-2, and were degraded via autophagy. Correlative light and electron microscopy revealed that these p62 bodies were more compact than stress granules and were often associated with the autophagic isolation membrane. Autophagy receptors NBR1 and TAX1BP1, but not OPTN1 or NDP52, behaved similarly to p62, and p62 bodies preferentially contained K63-linked ubiquitin chains. p62 body formation was also observed in human epithelial organoids in association with WIPI-2. Collectively, these results indicate that p62 bodies function as a platform of degradation under hyperosmotic stress.

DOI: https://doi.org/10.1038/s42003-025-09190-6
Cureus. 2025 Dec;17(12): e98514

The Mechanistic Target of Rapamycin (mTOR) Pathway as a Target of Anti-aging Therapies: The Role of Rapamycin and Its Analogs in the Regulation of Cellular Processes and Their Impact on Longevity.

Julia Zerdka, Patryk Brasse, Mateusz Piszka, Eliza Kwapien, Maria Kubicka, Jakub Bartkowski, Jan Banach, Hubert Dacyl, Aleksandra Owczarska.

  Aging of the body is a complex, multifactorial biological process, leading to a gradual loss of homeostasis, accumulation of molecular damage, and an increase in susceptibility to civilization diseases. In the face of a global aging population, pharmacological strategies are intensively sought that could slow down or partially reverse the aging process. One of the best-understood molecular pathways for regulating lifespan is the mechanistic target of rapamycin (mTOR) pathway, which integrates metabolic, hormonal, and environmental signals. Inhibition of mTOR, through the use of rapamycin and its analogs, consistently prolongs life in numerous animal models, improving age-related physiological functions. Preclinical evidence indicates that rapamycin prolongs the life of animals, improves metabolism, heart function, cognitive abilities, and immunity. In human clinical trials, low doses of rapamycin improve the immune response, reduce markers of skin aging, and are well tolerated. Rapamycin opens a new chapter in research into pharmacological slowing of aging. Understanding its effects on mTOR and autophagy could enable the development of effective interventions to support human longevity and metabolic health in the future, making these substances a promising direction for further research.

Keywords:  anti-aging medicine; healthspan; longevity medicine; mechanistic target of rapamycin; mtor inhibitors

DOI:  https://doi.org/10.7759/cureus.98514
Cells. 2025 Dec 30. pii: 68. [Epub ahead of print]15(1):

Proteasomal Degradation of Mutant Huntingtin Exon1 Regulates Autophagy.

Austin Folger, Chuan Chen, Phasin Gonzalez, Sophia L Owutey, Yanchang Wang.

  Accumulation of misfolded proteins is implicated in neurodegenerative diseases. One of these is Huntington's disease, which is caused by an expansion of trinucleotide (CAG) repeats in exon 1 of huntingtin gene (HTT). This expansion results in the production of mutant huntingtin exon1 protein (mHttEx1) containing polyglutamine tracks that is prone to cytotoxic aggregation. These mHttEx1 aggregates range from small soluble aggregates to large insoluble inclusion bodies. The mechanisms to clear mHttEx1 aggregates include ubiquitin-dependent proteasomal degradation and autophagy. For the proteasomal degradation of mHttEx1, ubiquitinated protein is first recognized by the Cdc48 complex for extraction and unfolding. For autophagy, mHttEx1 inclusion bodies are engulfed by an autophagosome, which fuses with the vacuole/lysosome and delivers cargo for vacuolar degradation. We name this autophagy IBophagy. In this study, we further show that the ubiquitination of mHttEx1 by the E3 ligase San1, its extraction and unfolding by the Cdc48 complex, and subsequent proteasomal degradation are all essential steps for mHttEx1 IBophagy in budding yeast, revealing a new layer of autophagy regulation and mHttEx1 cytotoxicity.

Keywords:  Cdc48 complex; IBophagy; autophagy; misfolded proteins; mutant huntingtin exon1 (mHttEx1); proteasome

DOI:  https://doi.org/10.3390/cells15010068
Cell. 2026 Jan 08. pii: S0092-8674(25)01418-7. [Epub ahead of print]

Structure of the lysosomal KICSTOR-GATOR1-SAMTOR nutrient-sensing supercomplex.

Christopher J Lupton, Charles Bayly-Jones, Shuqi Dong, Terrance Lam, Wentong Luo, Gareth D Jones, Chantel Mastos, Nicholas J Frescher, San S Lim, Alastair C Keen, Luke E Formosa, Hari Venugopal, Yong-Gang Chang, Michelle L Halls, Andrew M Ellisdon.

  The guanosine triphosphate (GTP)-bound state of the heterodimeric Rag GTPases functions as a molecular switch regulating mechanistic target of rapamycin complex 1 (mTORC1) activation at the lysosome downstream of amino acid fluctuations. Under low amino acid conditions, GTPase-activating protein (GAP) activity toward Rags 1 (GATOR1) promotes RagA GTP hydrolysis, preventing mTORC1 activation. KICSTOR recruits and regulates GATOR1 at the lysosome by undefined mechanisms. Here, we resolve the KICSTOR-GATOR1 structure, revealing a striking ∼60-nm crescent-shaped assembly. GATOR1 anchors to KICSTOR via an extensive interface, and mutations that disrupt this interaction impair mTORC1 regulation. The S-adenosylmethionine sensor SAMTOR binds KICSTOR in a manner incompatible with metabolite binding, providing structural insight into methionine sensing via SAMTOR-KICSTOR association. We discover that KICSTOR and GATOR1 form a dimeric supercomplex. This assembly restricts GATOR1 to an orientation that favors the low-affinity active GAP mode of Rag GTPase engagement while sterically restricting access to the high-affinity inhibitory mode, consistent with a model of an active lysosomal GATOR1 docking complex.

Keywords:  GATOR1; KICSTOR; RAG GTPase; Rag-Ragulator; S-adenosylmethionine; SAMTOR; SZT2; cell metabolism; cryo-EM; mTORC1

DOI:  https://doi.org/10.1016/j.cell.2025.12.005
Mol Cell. 2026 Jan 07. pii: S1097-2765(25)01015-9. [Epub ahead of print]

CASTOR1 and CASTOR2 respond to different arginine levels to regulate mTORC1 activity.

Chan Liu, Yifan Zhang, Yilun Wang, Min Wu, Yunchao Li, Jiashuai Wei, Jiawen Shi, Rong Wang, Li Su, Tingting Yang, Jin Li, Junjie Xiao, Jianping Ding, Tianlong Zhang.

  Mechanistic target of rapamycin complex 1 (mTORC1) is a central regulator of cell growth, responding to amino acid availability. While mTORC1 is modulated by amino acid sensors like CASTOR1, the mechanisms driving its dynamic response to fluctuating amino acid levels remain unclear. Here, we investigate the role of CASTOR2, an understudied CASTOR1 homolog, in regulating mTORC1 activity. We show that CASTOR1 and CASTOR2 bind to arginine similarly but differ in their sensitivity: CASTOR1 responds to low arginine levels, whereas CASTOR2 responds to high arginine concentrations. Both proteins interact with the GATOR2 component Mios, inhibiting its binding to GATOR1. Arginine binding to CASTOR1/2 induces conformational changes at the aspartate kinase, chorismate mutase, and TyrA (ACT) domain (ACT2-ACT4) interface, leading to its dissociation from Mios. Functionally, we demonstrate that CASTOR proteins are highly expressed in muscle tissue and, in C2C12 cells, they regulate mTORC1 and myogenesis in response to different arginine availability. These findings highlight how CASTOR proteins function as dual arginine sensors to fine-tune mTORC1 activity.

Keywords:  CASTOR1; CASTOR2; GATOR1; GATOR2; amino acid sensor; arginine; mTORC1 signaling; myogenesis

DOI:  https://doi.org/10.1016/j.molcel.2025.12.016
Cell Res. 2026 Jan;36(1): 11-37

Mitophagy in the pathogenesis and management of disease.

Qi Wang, Yu Sun, Terytty Yang Li, Johan Auwerx.

Mitophagy, an evolutionarily conserved quality-control process, selectively removes damaged mitochondria to maintain cellular homeostasis. Recent advances in our understanding of the molecular machinery underlying mitophagy - from receptors and stress-responsive triggers to lysosomal degradation - illustrate its key role in maintaining mitochondrial integrity and adapting mitochondrial function to ever-changing physiological demands. In this review, we outline the fundamental mechanisms of mitophagy and discuss how dysregulation of this pathway disrupts mitochondrial function and metabolic balance, driving a wide range of disorders, including neurodegenerative, cardiovascular, metabolic, and immune-related diseases, as well as cancer. We explore the dual role of mitophagy as both a disease driver and a therapeutic target, highlighting the efforts and challenges of translating mechanistic insights into precision therapies. Targeting mitophagy to restore mitochondrial homeostasis may be at the center of a large range of translational opportunities for improving human health.

DOI: https://doi.org/10.1038/s41422-025-01203-7
Cell Death Dis. 2026 Jan 08. 17(1): 10

Calcium overload induced mitochondrial and lysosomal dysfunction is regulated by Tousled-like kinase in a-synucleinopathy.

Fangyan Gong, Qi Cheng.

As a pathological hallmark of Parkinson's disease (PD), a-synucleinopathy induces various cellular damages, including calcium overload, mitochondrial and autophagic dysfunction, ultimately resulting in dopaminergic neuron death. However, the hierarchy of these detrimental events remains unclear. It is well established that a-synuclein can induce calcium overload through diverse mechanisms. To assess whether calcium overload plays a crucial detrimental role, we established a calcium overload model in Drosophila and conducted genetic screening. Our findings indicate that calcium overload caused mitochondrial damage and lysosomal dysfunction, leading to cell death, and these cytotoxic processes were significantly mitigated by the loss of Tousled-like kinase (TLK). Notably, the loss of TLK also ameliorated defects induced by a-synuclein overexpression in Drosophila. This suggests that calcium overload is a critical event in a-synucleinopathy. In mammalian cells and mice, calcium overload activated TLK2 (the homologue of Drosophila TLK) by enhancing TLK2 phosphorylation, which increases TLK2 kinase activity. Increased TLK2 phosphorylation was detected in the brains of GluR1Lc and a-synuclein overexpression mice, suggesting that TLK2 is activated under these pathological conditions. Furthermore, TLK2 knockout mice exhibited rescue of multi-aspect cytotoxicity induced by calcium overload and a-synuclein overexpression. Our research demonstrates that TLK2 activation by calcium overload appears to be a pivotal step in the progression of PD. This finding provides a potential link between calcium overload, the subsequent mitochondrial and lysosomal dysfunction observed in the disease.

DOI: https://doi.org/10.1038/s41419-025-08213-8
Biochim Biophys Acta Mol Basis Dis. 2026 Jan 06. pii: S0925-4439(25)00499-5. [Epub ahead of print] 168149

HMGA2 inhibits Pink1-mediated mitophagy and promotes vascular calcification.

Shengjue Xiao, Zhengdong Chen, Yiqing Yang, Liqun Ren, Yuyu Yao, Naifeng Liu.

  Mitochondrial dysfunction is implicated in the development of vascular calcification, whereas protective mitophagy helps to hinder its progression. HMGA2 plays a pivotal role in regulating mitochondrial integrity and mitophagy. However, the precise impact of HMGA2-controlled mitophagy on vascular calcification remains unclear. In our study, we observed elevated HMGA2 expression during both Vitamin D3-induced aortic calcification in mice and β-GP-induced calcification of mouse aortic vascular smooth muscle (MOVAS). Additionally, we identified dynamic changes in mitophagy in MOVAS and demonstrated that HMGA2 knockdown promoted mitophagy, exerting a protective effect against vascular calcification in both in vivo and in vitro settings. Preconditioning with the autophagy inhibitor chloroquine diminished the protective effect of HMGA2 knockdown on aortic calcification in mice by inhibiting mitophagy. Furthermore, we observed an increase in cytoplasmic HMGA2 levels in MOVAS following vascular calcification, along with its binding to PTEN induced kinase 1 (Pink1) in the cytoplasm. This affects the distribution of Pink1, which cannot be transferred to the mitochondrial outer membrane to initiate mitophagy. Subsequently, silencing Pink1 exacerbated mitochondrial damage and apoptosis by inhibiting mitophagy, thereby promoting vascular calcification in β-GP-treated MOVAS. Our results indicated that cytosolic HMGA2 bound to Pink1, inhibiting mitophagy by impeding Pink1's relocation from the cytosol to the mitochondria, thereby reducing mitophagy activation, inducing apoptosis, ultimately accelerating the transition of MOVAS to an osteoblastic phenotype and calcium deposition. In conclusion, inducing mitophagy pharmacologically by targeting HMGA2 may represent a promising therapeutic approach for managing vascular calcification.

Keywords:  Cytoplasm; HMGA2; Mitophagy; Pink1; Vascular calcification

DOI:  https://doi.org/10.1016/j.bbadis.2025.168149
Autophagy. 2026 Jan 04. 1-18

Measuring lysosome damage and lysophagy in vivo.

Zelai Wu, Hanyu Zhan, Zhiming Huang, Changjing Wang, Boran Li, Yepeng Hu, Zhida Chen, Wei Liu, Weihua Gong, Yongjuan Sang, Qiming Sun.

  Lysosome homeostasis is vital for cellular fitness due to the essential roles of this organelle in various pathways. Given their extensive workload, lysosomes are prone to damage, which can stimulate lysosomal quality control mechanisms such as biogenesis, repair, or autophagic removal - a process termed lysophagy. Despite recent advances highlighting lysophagy as a critical mechanism for lysosome maintenance, the extent of lysosome integrity perturbation and the magnitude of lysophagy in vivo remain largely unexplored. Additionally, the pathophysiological relevance of lysophagy is poorly understood. To address these gaps, it is necessary to develop quantifiable methods for evaluating lysosome damage and lysophagy flux in vivo. To this end, we created two transgenic mouse lines expressing a tandem fluorescent LGALS3/galectin 3 probe (tfGAL3), either constitutively or conditionally under Cre recombinase control, utilizing the property of LGALS3 to recognize damaged lysosomes. This tool enables spatiotemporal visualization of lysosome damage and lysophagy activity at single-cell resolution in vivo. Systemic analysis across various organs, tissues, and primary cultures from these lysophagy reporter mice revealed significant variations in basal lysophagy, both in vivo and in vitro. Additionally, this study identified substantial changes in lysosome integrity and lysophagy flux in different tissues under stress conditions such as starvation, acute kidney injury and diabetic modeling. In conclusion, these complementary lysophagy reporter models are valuable resources for both basic and translational research.Abbreviation: AAV: adeno-associated virus; ATG7: autophagy related 7; CA-tfGAL3: cre-recombinase-activated tandem fluorescent LGALS3; DAPI: 4',6-diamidino-2-phenylindole; DM: diabetes mellitus; ESCRT: endosomal sorting complex required for transport; GFP: green fluorescent protein; HFD: high-fat diet; Igs2/H11/Hipp11: intergenic site 2; IST1: IST1 factor associated with ESCRT-III; KI: knock-in; LAMP1: lysosomal-associated membrane protein 1; LGALS3: lectin, galactoside-binding, soluble, 3; LLOMe: L-leucyl-L-leucine methyl ester hydrobromide; MEFs: mouse embryonic fibroblasts; NaOx: sodium oxalate; PDCD6IP: programmed cell death 6 interacting protein; PTECs: proximal tubular epithelial cells; RFP: red fluorescent protein; STZ: streptozotocin; TAM: tamoxifen; tfGAL3: tandem fluorescent LGALS3; TMEM192: transmembrane protein 192.

Keywords:  In vivo; lysophagy; lysosome; lysosome damage; ratiometric probe

DOI:  https://doi.org/10.1080/15548627.2025.2608974
bioRxiv. 2025 Dec 23. pii: 2025.12.22.696043. [Epub ahead of print]

Spatial Regulation of Lysosomal Vesicle Acidification Along the Axon via mRAVE-Dependent v-ATPase Assembly.

Surbhi Verma, Nireekshit Addanki Tirumala, Xiaolin Zhu, Raffaella De Pace, Juan S Bonifacino.

Lysosomal acidification is essential for neuronal homeostasis, supporting degradative clearance and metabolic signaling in all neuronal domains. Yet, how lysosomal acidification is spatially regulated within neurons remains unclear. Here, we show that assembly of the membrane-embedded V 0 and cytosolic V 1 domains of the vacuolar H⁺-ATPase (v-ATPase) - the proton pump that drives lysosomal acidification - governs spatial and functional lysosome diversity. In non-neuronal cells, V 1 -V 0 association is higher in perinuclear lysosomes, correlating with increased acidity of this population. In neurons, axonal V 0 -positive vesicles move bidirectionally, whereas V 1 -V 0 -positive vesicles move almost exclusively in the retrograde direction, consistent with the higher acidity of retrograde lysosomal vesicles. Depletion of DMXL2, a subunit of the mRAVE complex that promotes V 1 -V 0 assembly, reduces V 1 association, acidification, transport, and proteolytic activity of retrograde lysosomal vesicles in the axon. Together, these findings reveal a spatially regulated mechanism for the acidification of axonal lysosomal vesicles and identify mRAVE-dependent v-ATPase assembly as a key determinant of this process. Subjects: Organelles, Trafficking, Disease.

DOI: https://doi.org/10.64898/2025.12.22.696043
JCI Insight. 2026 Jan 08. pii: e196835. [Epub ahead of print]

A TGF-β1/LEF1/β-catenin/JLP network motif regulates autophagy and tubule injury in renal fibrosis.

Chen Li, Meng Zhang, Maoqing Tian, Zeyu Tang, Yuying Hu, Yuyu Long, Xiaofei Wang, Liwen Qiao, Jiefei Zeng, Yujuan Wang, Xinghua Chen, Cheng Chen, Xiaoyan Li, Lu Zhang, Huiming Wang.

  Sustained injury to renal tubular epithelial cells (TECs), driven by excessive autophagy, is a critical mechanism underlying kidney fibrosis. Our previous work identified JLP-a TEC-expressed scaffolding protein-as an endogenous anti-fibrotic factor that counteracts TGF-β1-induced autophagy and fibrogenesis. However, the mechanism underlying JLP downregulation in renal fibrosis remains unclear. Here, we delineated a TGF-β1/LEF1/β-catenin/JLP axis that governed TEC autophagy through a dichotomous regulatory circuit. Under physiological conditions, low levels of β-catenin and LEF1 with minimal nuclear localization permit normal JLP expression, which in turn maintains autophagy in check. In contrast, during renal injury, TGF-β1 promoted the expression and nuclear translocation of β-catenin and LEF1, which together suppressed JLP transcription. This loss of JLP-mediated inhibition led to unchecked autophagy and exacerbated fibrotic damage. Analyses of kidney tissues from patients with CKD, murine fibrotic kidneys, and cultured HK-2 cells confirmed consistent JLP downregulation accompanied by upregulation and nuclear accumulation of LEF1 and β-catenin. Therapeutic intervention using the β-catenin/LEF1 inhibitor iCRT3 or LEF1-targeted silencing in murine fibrosis models restored JLP expression, attenuated TEC autophagy, and ameliorated renal fibrosis. These findings revealed an autoregulatory circuit controlling TEC autophagy and fibrogenesis, and supported LEF1 and β-catenin as potential therapeutic targets in CKD.

Keywords:  Autophagy; Cell biology; Chronic kidney disease; Fibrosis; Nephrology

DOI:  https://doi.org/10.1172/jci.insight.196835
Redox Biol. 2025 Dec 24. pii: S2213-2317(25)00492-6. [Epub ahead of print]89 103979

Superoxide signals for the mitophagy of dysfunctional mitochondria to maintain quality control.

William M Curtis, Patrick C Bradshaw.

  The mechanism of selecting dysfunctional mitochondria for mitophagy is only partially understood. Evidence suggests the mechanism involves reactions of superoxide (O2-•), hydrogen peroxide (H2O2), nitric oxide (NO•), peroxynitrite (ONOO-), carbonate radicals (•CO3-), nitrogen dioxide radicals (•NO2), hydroxyl radicals (•OH), oxygen (•O2• or O2), and carbon dioxide (CO2). However, the larger picture of how these reactions are organized to induce mitophagy is unclear. Extensive evidence suggests that increased mitochondrial matrix O2-• is associated with the mitophagy of dysfunctional organelles. In most cells, mitochondrial O2-• is mainly produced by the reaction of O2 with free radical intermediate forms of coenzyme Q (CoQ) and flavins, which are generated in substantial amounts in the inner membrane and matrix space of dysfunctional mitochondria. Mitochondrial O2-• plays two key roles in orchestrating mitophagy. First, it is dismutated by mitochondrial matrix superoxide dismutase 2 (SOD2) to H2O2. This diffusible messenger directs the nuclear and cytoplasmic compartments to prepare for mitophagy, including the generation of cytoplasmic NADPH and glutathione and the increased synthesis of membrane-diffusible NO•. Second, mitochondrial matrix space O2-• readily reacts with NO• to form ONOO-, which initiates a cascade of free radical reactions culminating in mitochondrial membrane depolarization and PINK1 and Parkin-driven mitophagy. Compelling observations that support the proposed mechanism are given. This mechanism could be targeted for the treatment of diseases characterized by dysfunctional mitophagy, such as Parkinson's disease. Because of the central role of mitochondrial O2-• as a sentinel for selective mitophagy, we have named this hypothesis the superoxide sentinel hypothesis of mitochondrial quality control.

Keywords:  DJ-1; Mitophagy; NADPH; Nitric oxide synthase; Parkinson's disease; Superoxide sentinel hypothesis

DOI:  https://doi.org/10.1016/j.redox.2025.103979
Inflammation. 2026 Jan 05.

LncRNA SNHG1 Knockdown Ameliorates HIV-1 gp120V3 Loop-Induced Microglial Neuroinflammation by Regulating the Autophagy Process.

Xueqin Yan, Qin Zuo, Xinyi Li, Yuanyuan Liu, Linlin Wang, Limeng Gan, Hanyang He, Saixian Wen, Haijie Tang, Huili Wang, Rui Pan, Yongmei Fu, Jun Dong.

  HIV-1-associated neurocognitive disorders (HAND) are characterized by chronic CNS inflammation. Previous studies have shown that HIV-1 gp120 causes learning and memory deficits in mice and neuroinflammation in neurons and microglia through impaired autophagy. However, the regulation of autophagy in this context is unclear. We found that lncRNA SNHG1 is upregulated in HIV-1 gp120-induced microglial inflammation. Reducing SNHG1 levels alleviates this inflammation by increasing early autophagy protein ULK1, decreasing late autophagy protein p62, and enhancing the LC3B II/I ratio. Autophagy inhibitors 3-MA and CQ can reverse or enhance the effects of SNHG1 knockdown on microglial inflammation. The study suggests that knocking down lncRNA SNHG1 may enhance early autophagy initiation and late degradation, reducing neuroinflammation. The Wnt pathway inhibitor FH535 further improved this effect by increasing ULK1 protein and the LC3B II/I ratio. In contrast, the Sirt1 inhibitor EX527 activated the Wnt pathway, decreased the LC3B II/I ratio, and worsened neuroinflammation. Thus, lncRNA SNHG1 knockdown might regulate autophagy via the Sirt1-Wnt pathway to alleviate HIV-1 gp120-induced neuroinflammation, offering a new approach for HAND prevention and treatment.

Keywords:  HIV-1 associated neurocognitive disorder; HIV-1 gp120; LncRNA SNHG1; Microglial neuroinflammation; Sirt1-Wnt pathway; The process of autophagy

DOI:  https://doi.org/10.1007/s10753-025-02414-1
Nat Rev Immunol. 2026 Jan 05.

Ubiquitination and autophagy in host-pathogen interactions: from immune surveillance to therapeutic targeting.

João Mello-Vieira, Ivan Dikic.

Ubiquitination, the covalent attachment of ubiquitin to proteins and other cellular substrates, is a dynamic post-translational modification that enables cells to rapidly respond to internal and external threats. Beyond its canonical role in targeting proteins for proteasomal degradation, ubiquitination orchestrates the assembly of signalling complexes that regulate innate and adaptive immune responses, modulates inflammatory pathways and directs selective autophagy to eliminate intracellular pathogens through lysosomal degradation. To persist and replicate within the host, viruses, bacteria and parasites have evolved diverse mechanisms to evade, manipulate or exploit the host's ubiquitin and autophagy machinery. Some pathogens subvert these systems to dampen immune surveillance, whereas others co-opt them to facilitate replication or dissemination. In this Review, we examine how ubiquitin and autophagy shape host-pathogen interactions, uncover common and pathogen-specific strategies of immune evasion, and discuss emerging therapeutic approaches that aim to leverage these interconnected pathways to enhance antimicrobial immunity.

DOI: https://doi.org/10.1038/s41577-025-01239-1
J Cell Biol. 2026 Mar 02. pii: e202506139. [Epub ahead of print]225(3):

Plasma membrane-to-lysosome FGR signaling regulates endocytosis-associated lysosome homeostasis.

Qiuyuan Yin, Jifan Qian, Xiao Ding, Xiaoxia Ren, Shalan Li, Zonghao Zhang, Meijiao Li, Long Xiao, Zhiguo Zhang, Fan Lai, Xuna Wu, Xiaojiang Hao, Chonglin Yang.

Transcriptional control of lysosome biogenesis is an important mechanism underlying cellular adaptation to stress. It is largely unclear how cell surface changes or signals induce alteration in lysosome numbers. By developing a Caenorhabditis elegans-based heterologous TFE3 activation system, we here identify the non-receptor tyrosine kinases SRC-1/-2 (C. elegans) and FGR (mammals) as critical regulators of lysosome biogenesis. In C. elegans, inactivation of src-1/-2 leads to nuclear enrichment of ectopically expressed TFE3 and increased intensity of lysosomal markers. In mammalian cells, FGR inhibition or deficiency similarly results in TFEB/TFE3-dependent lysosomal increase. FGR acts through AKT2 by promoting the activation of the latter. FGR associates with the plasma membrane but is internalized onto endosomes and reaches lysosomes along the endosome-lysosome pathway following endocytosis. Lysosomal FGR promotes AKT2 recruitment to lysosomes, where it phosphorylates TFEB/TFE3 to prevent their activation. Together, these findings reveal a plasma membrane-to-lysosome signaling axis that is required for endocytosis-associated lysosome homeostasis.

DOI: https://doi.org/10.1083/jcb.202506139
EMBO J. 2026 Jan 03.

The ATG8 E3-like ligases sense lysosomal damage and initiate ESCRT-mediated membrane repair.

Dale P Corkery, Deerada Wijayatunga, Benedita K L Feron, Laura K Herzog, Anastasia Knyazeva, Yao-Wen Wu.

  After damage from pathogenic, chemical or physical stress, endolysosomal membranes are repaired and resealed by the endosomal sorting complex required for transport (ESCRT) machinery, but how this membrane damage is sensed and translated into ESCRT recruitment is poorly understood. Here, we identify the two ATG8 E3-like ligases, ATG16L1 and TECPR1, as ion-dependent catalysts for ESCRT recruitment to damaged lysosomal membranes. Leakage from perforated lysosomes induces the proton sensitive V-ATPase-dependent recruitment of ATG16L1-ATG5-ATG12 complexes, or the calcium-sensitive sphingomyelin-dependent recruitment of TECPR1-ATG5-ATG12 complexes. In both cases, the E3-like complex-dependent ATG5-ATG12 conjugate is required for ESCRT recruitment to the damaged membrane, and stabilization of the ESCRT machinery. Collectively, this study establishes the ATG8 E3-like ligases as membrane damage sensors for ESCRT-mediated membrane repair.

Keywords:  ATG8 E3-like Ligases; CASM; ESCRT; Lysosomal Membrane Integrity; Membrane Damage Sensor

DOI:  https://doi.org/10.1038/s44318-025-00672-1
FASEB J. 2026 Jan 15. 40(1): e71367

Targeting Fibrosis: ALA-PDT Triggers PINK1/Parkin-Dependent Mitophagy and Apoptosis in Fibroblasts.

Jie Ren, Jingtao Zhang, Min Jiang, Qinyi Chen, Xiaoyao Fan, Ye Liu, Ying Ma.

  Fibroblasts are key contributors to fibrosis due to their hyperproliferative and apoptosis-resistant phenotype. This study explores how 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) induces apoptosis in fibroblasts by modulating mitochondrial quality control. ALA-PDT significantly reduces cell viability and proliferation, increases LDH release, and triggers apoptotic signaling. Mechanistically, ALA-PDT promotes excessive accumulation of mitochondrial and cytosolic reactive oxygen species (ROS), leading to mitochondrial dysfunction and energy stress. These alterations activate the AMPK/mTOR signaling cascade, which in turn upregulates PINK1/Parkin-mediated mitophagy. Suppression of mitophagy through siRNA targeting PINK1 or Parkin, or with pharmacological autophagy inhibitors, markedly attenuates ALA-PDT-induced apoptosis, confirming the pivotal role of mitophagy in this process. Transmission electron microscopy shows abundant autophagosome formation, while Western blotting validates the amount of mitophagy-related and apoptotic proteins. These findings establish a mechanistic link between ALA-PDT-induced oxidative stress and mitophagy-dependent apoptosis, identifying a novel anti-fibrotic pathway involving ROS-AMPK/mTOR-PINK1/Parkin signaling. The results offer a compelling molecular basis for using ALA-PDT as a targeted therapeutic strategy against fibrotic diseases by promoting the selective elimination of activated fibroblasts.

Keywords:  ALA‐PDT; AMPK/mTOR signaling; PINK1/Parkin pathway; fibroblast apoptosis; fibrosis therapy; mitophagy

DOI:  https://doi.org/10.1096/fj.202502230RR
bioRxiv. 2025 Dec 23. pii: 2025.12.20.695697. [Epub ahead of print]

Regulation of the Rheb GTPase via GATOR1 Complex.

Aditi Prabhakar, William B Mair.

mTORC1 coordinates cellular growth and metabolism by integrating inputs from both amino acids and growth factors, and its activation requires two upstream branches involving the Rag GTPases and the Rheb GTPase. These branches are regulated by distinct GAP complexes: GATOR1 (Depdc5-Nprl2-Nprl3) inhibits RagA/B, and TSC (TSC1-TSC2-TBC1D7) inhibits Rheb. Despite the prevailing view that these pathways converge only at mTORC1 itself, several observations suggest upstream crosstalk. This gap is especially striking in organisms like C. elegans and S. cerevisiae that lack the TSC complex yet maintain fully responsive mTORC1 signaling. How these inputs are dynamically coordinated under complex physiological conditions and in organisms lacking the key components remain unknown. We performed unbiased quantitative proteomics in C. elegans and identified the GATOR1 complex as a previously unrecognized RHEB-1 ( C. elegans ortholog of Rheb) interactor. Through biochemical validation in human cells, we show that nucleotide-free Rheb associates with the Nprl2-Nprl3 subunits of GATOR1, whereas GTP-bound or membrane-detached Rheb mutants fail to bind. Nutrient stress, but not direct pharmacologic inhibition of mTORC1, robustly induced this interaction. In TSC2-null cells, where Rheb is constitutively GTP-loaded, Rheb-Nprl2/3 binding was strongly diminished and was restored by expressing the nucleotide-free Rheb S20N mutant, demonstrating that Rheb's nucleotide state governs this interaction. Pulldown assays confirmed that the Nprl2/3 heterodimer is sufficient for binding nucleotide-free Rheb. Structural modeling using AlphaFold3 consistently positioned Rheb at a conserved site on Nprl3 distinct from the RagA/B GAP-active surface of Nprl2, supporting a non-catalytic mode of association. Together, these findings identify a conserved, nutrient-regulated physical interaction between Rheb and the Nprl2/3 subunits of GATOR1, revealing a previously unrecognized point of convergence between the growth factor and amino acid branches of the mTORC1 pathway. This model provides a direct molecular link between the Rag and Rheb branches, furthering our understanding of how nutrient stress fine-tunes mTORC1 signaling.

DOI: https://doi.org/10.64898/2025.12.20.695697
Essays Biochem. 2025 Dec 22. pii: EBC20253045. [Epub ahead of print]69(5):

The many faces of p97/Cdc48 in mitochondrial homeostasis.

Jonathan Ram, Michael H Glickman.

  Through its various roles in protein quality control, membrane dynamics, and cellular survival pathways, the AAA+ ATPase p97/valosin-containing protein emerges as a significant regulator of mitochondrial homeosta sis. This review comprehensively examines the multifaceted functions of p97 in mitochondrial biology, spanning from mitochondria-associated degradation to newly discovered functions in organellar cross-talk and disease pathogenesis. Underlying its cellular importance, p97 mutations are found in amyotrophic lateral sclerosis and frontotemporal dementia. To elucidate its mechanistic contribution to these processes, we provide a detailed table (Table 1) listing all known mitochondrial Cdc48/p97 substrates and associ ated proteins, categorized by their respective pathways. Recruitment to most of these substrates occurs by specialized adaptors, including Doa1/phospholipase A-2-activating protein, UBXD8, and UBXN1. p97 orchestrates the extraction and proteasomal degradation of outer mitochondrial membrane proteins, which are essential for maintaining mitochondrial integrity. For example, by controlling the turnover of fusion factors MFN1/2 and fission machinery, p97 regulates mitochondrial dynamics. p97 also governs apoptotic signaling through the regulated degradation of anti-apoptotic factors, such as myeloid cell leukemia-1 and VDAC, thereby modulating mitochondrial permeability. In mitophagy, p97 enables the clearance of damaged organelles by extracting ubiquitinated substrates and recruiting autophagy machinery. Beyond proteolysis, p97 facilitates recycling of endoplasmic reticulum-mitochondria contact sites through regulation of UBXD8-dependent lipid metabolism. Recent discoveries have revealed p97's involvement in pathogen host interactions and circular RNA-mediated regulation, thereby expanding our understanding of its cellular functions. The emerging picture positions p97 as an integrative hub co-ordinating mitochondrial protein homeostasis, organellar dynamics, and cell fate decisions, with therapeutic potential for metabolic and neurodegenerative disorders.

Keywords:  Cdc48; ERAD; MAD; P97; VCP; mitochondria; mitostasis; proteasome; ubiquitin

DOI:  https://doi.org/10.1042/EBC20253045
Circulation. 2026 Jan 06.

Inhibition of Annexin A2 Facilitates PHB2-Mediated Mitophagy in Cardiomyocytes to Alleviate Cardiac Injury and Remodeling After Infarction.

Ke-Qiong Deng, Zhendong Xu, Qiong-Xin Wang, Huan-Huan Cai, Di Fan, Qingqing Wu, Xiao-Jing Zhang, Peng Zhang, Zhi-Gang She, Xingguo Liu, Xianqing Li, Zhibing Lu.

   BACKGROUND: Mitophagy is critically involved in cardiac injury and repair after myocardial infarction (MI), whereas the annexin A family plays an important role in mitophagy. However, the intrinsic molecular underpinnings that orchestrate the homeostasis of mitophagy in the infarcted heart remain to be fully characterized. Here, we aimed to evaluate the role of ANXA2 (annexin A2) in cardiac mitophagy in response to MI.
METHODS: Transcriptome analyses were conducted to identify differentially expressed genes and enriched pathways. Mitophagy, mitochondrial function, and cardiac injury and remodeling were analyzed in MI mice and neonatal rat ventricular myocytes with cardiomyocyte-specific ANXA2 knockdown or overexpression, as well as in models with ANXA2 knockdown combined with PHB2 (prohibitin 2) silencing. Immunoprecipitation, mass spectrometry, and glutathione S-transferase pull-down assays were used to identify the interacting proteins of ANXA2.
RESULTS: We showed that ANXA2 was highly expressed in murine and human ischemic failing hearts, whereas increased circulating ANXA2 positively correlated with cardiac injury in patients with acute MI. Moreover, cardiomyocyte-specific ANXA2 depletion averted cardiac mitophagy inactivation, oxidative stress, cell death, and inflammatory cell infiltration, leading to significant improvements in infarct size, heart function, and cardiac remodeling after MI. Conversely, ANXA2 overexpression in cardiomyocytes suppressed mitophagy to exacerbate cardiac injury and deteriorate heart failure after MI. Moreover, ANXA2 silencing and overexpression, respectively, in neonatal rat ventricular myocytes under hypoxia in vitro recapitulated the in vivo findings on mitochondrial function and cell death. Mechanistically, we found that ANXA2 directly interacted with the mitophagy receptor PHB2 to competitively block the binding of LC3B with PHB2 and promote PHB2 proteasomal degradation through K48-linked polyubiquitination mediated by the E3 ligase TRIM29, resulting in mitophagy inhibition under hypoxia. Consequently, PHB2 knockdown abrogated the protective effects of ANXA2 deficiency on mitochondrial function, oxidative stress, and cell viability in stressed myocytes in vitro, as well as on heart function and remodeling under MI in vivo.
CONCLUSIONS: These findings highlight the significance of ANXA2 inhibition as a molecular brake on mitophagy inactivation in cardiomyocytes under MI and uncover an ANXA2-mediated posttranslational mechanism essential for maintaining mitochondrial homeostasis and alleviating heart failure after MI.

Keywords:  cardiomyocyte; mitochondrial function; mitophagy; myocardial infarction; proteasomal degradation

DOI:  https://doi.org/10.1161/CIRCULATIONAHA.125.077780
Proc Natl Acad Sci U S A. 2026 Jan 13. 123(2): e2516471123

USP25 inhibition ameliorates Parkinson's disease by restoring mitophagy.

Yanqi Xu, Keshuo Jin, Jiaqing Chen, Zhongding Li, Zhenhu Zhu, Xian Su, Jiangyun Shen, Bincheng Zhou, Zijun Cao, Liyan Lou, Deyu Deng, Jianzhao Zhang, Baohua Liu, Yangping Shentu, Xu Wang.

  Parkinson's disease (PD) is a progressive neurodegenerative disease that casts a significant shadow over global health and the identification of therapeutic targets for PD will empower more effective clinical treatment. The gene encoding the deubiquitinating enzyme USP25 has been identified as a susceptible locus for PD, but the role of USP25 in PD remains unknown. In this study, we found that USP25 exacerbated dopaminergic neuronal loss and motor deficits in murine models of PD by sabotaging the mitophagy machinery. USP25 physically interacted with the autophagy receptor optineurin and disrupted its linkage with K63-specific polyubiquitin chains, leading to impaired mitophagy and the accumulation of damaged mitochondria. Genetic ablation or pharmacological inhibition of USP25 significantly restored mitophagy and thereby impeded the neurodegenerative progression in PD model mice. Collectively, our results unravel a pivotal role of USP25 in PD and identify USP25 as a pharmacological target for the development of PD drugs.

Keywords:  Parkinson’s disease; USP25; mitophagy; optineurin; ubiquitination

DOI:  https://doi.org/10.1073/pnas.2516471123
Exp Neurol. 2026 Jan 06. pii: S0014-4886(26)00003-8. [Epub ahead of print] 115640

Astrocytic TPK1 mitigates amyloid pathology via TFEB-mediated endocytosis.

Shu-Zhen Zhang, Yuan Ma, Yu Ding, Yan-Qing Yin, Bing-Wei Wang, Gang Hu, Jia-Wei Zhou.

  Alzheimer's disease (AD), the leading cause of dementia, is characterized by amyloid-beta (Aβ) plaques, neurofibrillary tangles, and progressive neurodegeneration. Deregulation of glial cell activity plays an important role in the amyloid pathology. However, it is still unclear how changes in astrocytes contribute to Aβ deposition and clearance in AD. Here, we showed that deficiency of astrocytic thiamine pyrophosphokinase 1 (Tpk1), exacerbated Aβ burden leading to exacerbated spatial memory deficits in a mouse model of AD. While selective overexpression of Tpk1 in astrocytes ameliorated cognitive decline and significantly reduced hippocampal and cortical Aβ plaque burden. Enhanced Tpk1 expression augmented astrocyte endocytic capacity. Mechanistically, Tpk1-promoted endocytic activity depended on the activation of transcription factor EB (TFEB)-mediated pathways. Collectively, our findings demonstrate that astrocytic TPK1 mitigates cognitive impairment in 5xFAD mice by upregulating TFEB expression, thereby enhancing astrocyte-mediated engulfment and degradation of neurotoxic aggregates, including Aβ. This study suggests that astrocytic TPK1/TFEB pathway is a promising target for developing disease-modifying AD therapies.

Keywords:  Alzheimer's disease; Amyloid-β; Astrocyte; TFEB; TPK1

DOI:  https://doi.org/10.1016/j.expneurol.2026.115640
J Cell Biol. 2026 Feb 02. pii: e202212064. [Epub ahead of print]225(2):

Rsp5/NEDD4 and ESCRT regulate TDP-43 toxicity and turnover via an endolysosomal clearance mechanism.

Aaron Byrd, Lucas J Marmorale, Sophia Marcinowski, Megan M Dykstra, Vanessa Addison, Sami J Barmada, J Ross Buchan.

A pathological hallmark in >97% of amyotrophic lateral sclerosis (ALS) cases is the cytoplasmic mislocalization and aggregation of TDP-43, a nuclear RNA-binding protein, in motor neurons. Driving clearance of cytoplasmic TDP-43 reduces toxicity in ALS models, though how TDP-43 clearance is regulated remains controversial. We conducted an unbiased yeast screen using high-throughput dot blotting to identify genes that affect TDP-43 levels. We identified ESCRT complex genes, which induce membrane invagination (particularly at multivesicular bodies; MVBs) and genes linked to K63 ubiquitination (particularly cofactors of the E3 ubiquitin ligase Rsp5; NEDD4 in humans), as drivers of TDP-43 endolysosomal clearance. TDP-43 colocalized and bound Rsp5/NEDD4 and ESCRT proteins, and perturbations to either increased TDP-43 aggregation, stability, and toxicity. NEDD4 also ubiquitinates TDP-43. Lastly, TDP-43 accumulation induces giant MVB-like vesicles, within which TDP-43 accumulates in a NEDD4-dependent manner. Our studies shed light on endolysosomal-mediated cytoplasmic protein clearance, a poorly understood proteostasis mechanism, which may help identify novel ALS therapeutic strategies.

DOI: https://doi.org/10.1083/jcb.202212064
Nat Commun. 2026 Jan 08.

Dynamins maintain nuclear envelope homeostasis and genome stability.

Célia Aveleira, Thibaud Martial, Loïc Carrique, Rita Gaspar, Ana Caulino-Rocha, Izaak Myatt, Franz Wendler, Pauline Lascaux, Misha Le Claire, James Bancroft, Carl Smythe, Kristijan Ramadan, Nuno Raimundo, Ira Milosevic.

The nuclear envelope is a protective barrier for the genome and a mechanotransduction interface between cytoplasm and nucleus, whose malfunction disrupts nucleocytoplasmic transport, compromises DNA repair, accelerates telomere shortening, and promotes genomic instability. Mechanisms governing nuclear envelope remodeling and maintenance in interphase and post-mitotic cells remain poorly understood. Here, we report a role for dynamins, a family of essential brain-enriched membrane- and microtubule-binding GTPases, in preserving nuclear envelope and genomic homeostasis. Cells lacking dynamins exhibit nuclear envelope dysmorphisms, including buds with long narrow necks where damaged DNA frequently accumulates. These cells also show impaired autophagic clearance, reduced levels of key DNA repair proteins, and aberrant microtubules. Nocodazole treatment restores nuclear morphology and reduces DNA damage. Collectively, the data reveal that dynamins promote nuclear envelope homeostasis and removal of damaged DNA via their GTPase activity and interaction with microtubules, providing insights into mechanisms that uphold genome stability and counteract aging-related pathologies.

DOI: https://doi.org/10.1038/s41467-025-68130-4