bims-auttor 2026-02-22 papers

bims-auttor

Biomed News

on Autophagy and mTOR

Issue of 2026–02–22
25 papers selected by
Viktor Korolchuk, Newcastle University

Core principles of autophagy initiation mechanisms.
Decoding the brain's ATG8 paralog code: LC3-GABARAP specialization at synapses and the astrocyte-neuron interface.
Hyperactivation of mTORC1 signaling mediates folliculin deficiency-induced pulmonary cyst formation in Birt-Hogg-Dubé syndrome.
Extracellular matrix sensing regulates intratumoral heterogeneity of autophagic flux.
The dual role of autophagy in cartilage degradation: from mechanisms to targeted therapeutics.
The autophagy-senescence axis as a threshold model of aging and therapeutic targeting.
Golgi Membrane-Associated Degradation (GOMED), a New Intracellular Proteolysis Mechanism.
Curcumin Rescues Oxidative Stress-Induced Impairment of PINK1/Parkin Pathway-Mediated Mitophagy in APOE4-Expressing Astrocytes.
A New biosensor illuminates the driving force behind mitochondrial outer membrane rupture.
Alphaherpesvirus UL48 homologs degrade STING1 by selective autophagy.
Mechanistic insights into non-coding RNAs regulate autophagy in chondrocytes and their contribution to osteoarthritis.
A switchable role of neuronal BNIP3L/NIX in mitochondrial fate: fission or finish.
Lysosome pH Dynamics in Physiology and Disease: Molecular Mechanisms and Therapeutic Insights.
Phosphatidylinositol transfer protein α binds microcolins in its open conformation.
CREG1 Attenuates Osteoarthritis Progression by Suppressing Chondrocyte Pyroptosis Through the PINK1/Parkin-Mediated Mitophagy Pathway.
Hyperglutaminolysis drives senescence and aging through arginine-mTORC1 axis activation.
Ouabain Suppresses CD63 Loading into Extracellular Vesicles via Na+/K+-ATPase-Dependent Localization to Autophagosomes.
Phase separation of OPTN initiates mitophagy to orchestrate craniofacial bone mineralization.
Clec16a maintains definitive hematopoietic stem and progenitor cells via mitophagy.
A universal phase-plane model for in vivo protein aggregation.
A guide to selecting high-performing antibodies for Optineurin (UniProt ID: Q96CV9) for use in western blot, immunoprecipitation, and immunofluorescence.
Molecular mechanisms underlying the lifespan and healthspan benefits of dietary restriction across species.
Ferritinophagy and organ injury.
Lipidation as a post-translational code for protein liquid-liquid phase separation.
Neuroprotective effects of idebenone in a zebrafish model of Parkinson's disease via regulating autophagy, mitigating apoptosis and oxidative stress.

Nat Struct Mol Biol. 2026 Feb 20.

Core principles of autophagy initiation mechanisms.

Tetsuya Kotani, Hitoshi Nakatogawa.

Autophagy is a conserved intracellular degradation system essential for maintaining cellular homeostasis and adapting to a variety of environmental or metabolic cues. Different types of autophagy are induced in response to various physiological signals through distinct mechanisms. In this Review, we highlight recent advances in understanding the molecular mechanisms that induce autophagic degradation of cytoplasmic material in bulk upon nutrient or energy deprivation, and those that trigger the selective autophagic removal of specific cellular components for their quality or quantity control. We discuss mechanistic principles shared across different types of autophagy, such as phase-separation-mediated assembly and activation of related factors, and the coordination between cargo recognition and membrane biogenesis, delineating how diverse mechanisms converge on core principles to ensure context-specific control of autophagy initiation.

DOI: https://doi.org/10.1038/s41594-026-01752-4
Front Cell Dev Biol. 2026 ;14 1762891

Decoding the brain's ATG8 paralog code: LC3-GABARAP specialization at synapses and the astrocyte-neuron interface.

Haneul Choi, Seung-Min Lee, Jin-A Lee.

  Macroautophagy is essential for the long-term health of neurons and astrocytes in the central nervous system (CNS). The six mammalian ATG8 paralogs (LC3A/B/C and GABARAP/GABARAPL1/L2) exhibit an emerging "ATG8 code"-a division of labor among these proteins that assigns specialized roles in the autophagy pathway to each paralog, enabling fine-tuned proteostasis at synapses and the astrocyte-neuron interface. This review synthesizes how LC3 versus GABARAP mediate distinct steps of autophagy (LC3 primarily governs cargo recruitment and phagophore expansion, whereas GABARAP drives autophagosome maturation, transport, and lysosomal fusion) and how these molecular distinctions translate into functional differences in neurons versus astrocytes. Neurons coordinate autophagy across long axons and synapses: presynaptic autophagy clears aging synaptic vesicles and organelles, while postsynaptic autophagy modulates receptor turnover and synaptic plasticity. Astrocytes, by contrast, leverage autophagy for metabolic support and clearance of extracellular debris (e.g., amyloid-β plaques), interfacing with neuronal autophagy via transcellular mechanisms. Dysregulation of these processes underlies diverse CNS disorders: impaired autophagic flux and aggregate clearance contribute to neurodegenerative diseases (Alzheimer's and Parkinson's), whereas selective autophagy deficits at synapses disrupt circuit homeostasis (implicated in epilepsy and autism). Finally, we highlight emerging methodologies-from multi-omics and live imaging to optogenetics and targeted therapeutics-that are illuminating this specialized autophagy network and opening novel avenues for intervention.

Keywords:  GABARAP family protein; LC3 family protein; autophagy; brain; neurological disorders; synapse

DOI:  https://doi.org/10.3389/fcell.2026.1762891
J Clin Invest. 2026 Feb 16. pii: e194300. [Epub ahead of print]136(4):

Hyperactivation of mTORC1 signaling mediates folliculin deficiency-induced pulmonary cyst formation in Birt-Hogg-Dubé syndrome.

Ke Cao, Hui Chen, Ling Chu, Hong-Jun Wang, Jianhua Zhang, Yongfeng Luo, Joanne Chiu, Damir Khabibullin, Nicola Alesi, Matthew E Thornton, Brendan H Grubbs, Ali Ataya, Nishant Gupta, Francis X McCormack, Kathryn A Wikenheiser-Brokamp, Elizabeth P Henske, Wei Shi.

  Germline loss-of-function folliculin (FLCN) gene mutations cause Birt-Hogg-Dubé (BHD) syndrome, in which pulmonary cysts are present in up to 90% of the patients. The pathogenic mechanisms underlying lung cyst development in BHD are almost entirely unknown because of the limited availability of BHD patient lung samples and the lack of authentic BHD lung disease models. We generated lung mesenchyme-specific and lung epithelium-specific Flcn-knockout mice using a Cre/loxP approach. We found that deletion of Flcn in lung mesenchymal cells, but not in lung epithelial cells, resulted in alveolar enlargement starting from early postnatal life, with evidence of cyst formation in adult mice, resembling the pulmonary disease in human BHD. These changes were associated with increased mechanistic target of rapamycin complex 1 (mTORC1) activity in the lungs of both patients with BHD and Flcn-knockout mice. Attenuation of mTORC1 activity by knocking out Raptor gene (Rptor) or pharmacologic inhibition using rapamycin substantially rescued the pulmonary pathology caused by Flcn deletion in mice. Taken together, these human and mouse data support a model in which mTORC1 hyperactivation drives pulmonary cystic pathology in BHD.

Keywords:  Cell biology; Development; Mouse models; Pulmonology; Tumor suppressors

DOI:  https://doi.org/10.1172/JCI194300
Cell. 2026 Feb 16. pii: S0092-8674(25)01502-8. [Epub ahead of print]

Extracellular matrix sensing regulates intratumoral heterogeneity of autophagic flux.

Mohamad Assi, Ruohong Wang, Emily A Kawaler, Albert S W Sohn, M Zahidunnabi Dewan, Despoina Kalfakakou, Joel Encarnacion-Rosado, Kevin S Kapner, Koelina Ganguly, Joao A Paulo, Diane M Simeone, Andrew J Aguirre, Robert S Banh, Alec C Kimmelman.

  Autophagy, a programmed self-eating process, underlies the progression of multifactorial diseases like pancreatic ductal adenocarcinoma (PDA). Except for nutrient availability, the contribution of microenvironmental factors to autophagy regulation is not well understood. Through integrating functional genomics and tumor-like 3D cultures, we show that human PDA cells regulate their autophagy levels by sensing the extracellular matrix (ECM) via the integrinα3-Hippo-YAP1 axis. The spatial proximity of PDA cells to the ECM shapes their intracellular autophagy levels, leading to heterogeneous biological responses. Specifically, PDA cells with low autophagy levels are proliferative, whereas those with high autophagy levels display better tolerance to chemotherapies. Targeting the ECM-mediated autophagy regulation reduces autophagic heterogeneity, alters PDA growth, and shapes antitumor responses to FDA-approved therapies. In summary, we have characterized a non-metabolic regulation of autophagy through ECM sensing, opening the possibility to investigate and target ECM-specific outputs in diseases.

Keywords:  autophagy; cancer; extracellular matrix sensing; fibrosis; lysosome

DOI:  https://doi.org/10.1016/j.cell.2025.12.053
Front Cell Dev Biol. 2026 ;14 1737547

The dual role of autophagy in cartilage degradation: from mechanisms to targeted therapeutics.

Jiahua Mei, Shenghao Zhang, Xinrong Cui, Ruiping Yang, Jin Ke, Lili Cui, Lin Tan, Shan Zhu, Yunshu Ma.

  Autophagy is a highly conserved cellular degradation and recycling process that plays a pivotal role in maintaining cartilage homeostasis. Normal autophagy is essential for the survival of chondrocytes and the preservation of the extracellular matrix (ECM); however, a decline in autophagic function may lead to the accumulation of damaged organelles and macromolecules, thereby reducing chondrocyte vitality and promoting apoptosis, which in turn contributes to the development of osteoarthritis (OA). This review summarizes the biological processes of autophagy, the interaction between autophagy and cartilage degeneration, as well as the interplay between autophagy and cellular senescence, apoptosis, inflammation, and oxidative stress. Furthermore, we explore key autophagic targets for the regulation of OA and discuss autophagy-targeting therapies, including mTOR inhibitors, AMPK activators, and natural products that target autophagy, along with emerging strategies aimed at modulating autophagy. Finally, the article highlights the challenges in the development of autophagy-targeting drugs for OA treatment and presents important scientific issues that warrant further investigation to guide future research.

Keywords:  autophagy; cartilage degeneration; cellular apoptosis; chondrocytes; osteoarthritis

DOI:  https://doi.org/10.3389/fcell.2026.1737547
Redox Biol. 2026 Feb 10. pii: S2213-2317(26)00077-7. [Epub ahead of print]91 104079

The autophagy-senescence axis as a threshold model of aging and therapeutic targeting.

Md Entaz Bahar, Jin Seok Hwang, Trang Huyen Lai, Kazi-Marjahan Akter, Rizi Firman Maulidi, Deok Ryong Kim.

  Autophagy and cellular senescence are fundamental stress-response programs that critically shape aging and disease progression, yet their functional relationship has remained paradoxical. Autophagy is traditionally viewed as a cytoprotective process that preserves cellular homeostasis and delays senescence. In contrast, emerging evidence demonstrates that autophagy is also indispensable for the survival and pathological activity of established senescent cells. In this review, we propose a "threshold model" to reconcile these opposing roles and to provide a unified framework linking signal transduction, organelle quality control, and therapeutic intervention. According to this model, autophagy exerts stage-dependent functions governed by stress intensity and disease progression. Below a critical damage threshold, robust autophagic flux suppresses senescence initiation by maintaining mitochondrial integrity, limiting oxidative stress, and preserving proteostasis. Once this threshold is exceeded, autophagy is functionally reprogrammed to sustain the metabolic and biosynthetic demands of senescent cells, including production of the senescence-associated secretory phenotype (SASP). We highlight key signaling nodes that regulate this transition, including mTORC1, AMPK, p53, and p62, as well as spatial and organelle-specific mechanisms such as the TOR-autophagy spatial coupling compartment (TASCC), mitophagy failure, lipophagy blockade, and aberrant nucleophagy. These processes converge on innate immune pathways, notably cGAS-STING and NF-κB signaling, to drive chronic inflammation and tissue dysfunction. Importantly, we extend this mechanistic framework to clinical translation, synthesizing evidence from ongoing trials in cancer, neurodegeneration, metabolic liver disease, and fibrosis. We argue that effective targeting of the autophagy-senescence axis requires precision gerontology, integrating dynamic biomarkers to guide stage-specific interventions-autophagy activation for prevention and autophagy inhibition or senolysis for established disease. This threshold-based perspective provides a rational foundation for next-generation therapeutic strategies targeting aging and age-related disorders.

Keywords:  Autophagy; Cellular stress; Senescence; Targeted senotherapy; Threshold-model

DOI:  https://doi.org/10.1016/j.redox.2026.104079
Subcell Biochem. 2026 ;111 331-350

Golgi Membrane-Associated Degradation (GOMED), a New Intracellular Proteolysis Mechanism.

Shigeomi Shimizu, Shinya Honda, Satoru Torii, Satoko Arakawa, Masatsune Tsujioka, Hirofumi Yamaguchi, Hajime Tajima Sakurai.

  The Golgi apparatus is a crucial organelle that is involved in various cellular processes, including cellular secretion, and is primarily responsible for the modification, sorting, and transport of proteins and lipids. However, recently, we discovered a novel Golgi function, namely, Golgi membrane-associated degradation (GOMED). GOMED is a cellular function in which the trans-Golgi membrane undergoes deformation and becomes spherical, breaking down proteins and lipids that have been internalized. This process is conserved from yeast to mammalian cells. GOMED primarily plays a role in the quality control of hormones, cytokines, and cell membrane receptors that pass through the Golgi apparatus, and is crucial for maintaining the normal function of pancreatic β cell, neurons, and intestinal epithelial cells. Therefore, abnormalities in GOMED can lead to neurodegenerative diseases and inflammatory bowel diseases.

Keywords:  Autophagy; GOMED; Golgi apparatus; ULK1; Wipi3

DOI:  https://doi.org/10.1007/978-3-032-16833-7_14
Mol Neurobiol. 2026 Feb 18. 63(1): 454

Curcumin Rescues Oxidative Stress-Induced Impairment of PINK1/Parkin Pathway-Mediated Mitophagy in APOE4-Expressing Astrocytes.

Jia-Xin Yu, Wen-Xuan Zhang, Pu-Yu Li, Yi-Liang Yang, Han-Chang Huang.

  Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized primarily by deterioration in memory, cognition, and learning ability. Its etiology is complex and influenced by multiple factors, including genetics and environment. With advancing research into mitochondrial function and mechanisms, impaired mitophagy has been proposed as a significant mechanism contributing to AD. The ApoE ε4 allele, a high-risk genetic factor for AD, may play a key role in disease pathogenesis by inducing mitophagy dysfunction and apoptosis. From the perspective of APOE gene polymorphisms, this study investigates abnormal changes in mitochondrial function and autophagy in humanized APOE4 mice primary astrocytes under oxidative stress, as well as the regulatory effect of curcumin (Cur) on mitophagy and oxidative stress-induced apoptosis, thereby exploring its potential to ameliorate AD through targeting mitophagy. Mitochondrial function analysis revealed that APOE4 expression reduced the antioxidant capacity and respiratory function of primary astrocytes, leading to mitochondrial membrane damage, intracellular reactive oxygen species (ROS) accumulation, and decreased ATP production. Curcumin effectively protected mitochondrial integrity, reduced the number of damaged mitochondria, improved overall mitochondrial function, and helped maintain mitochondrial homeostasis involving in PINK1/Parkin pathway. Regarding autophagy and apoptosis, curcumin was shown to restore autophagic flux, mitigate autophagy disruption caused by oxidative stress, and reverse early-stage apoptosis.

Keywords:  APOE4; Astrocytes; Curcumin; Mitochondrial function; Mitophagy; Oxidative stress

DOI:  https://doi.org/10.1007/s12035-026-05744-9
Autophagy Rep. 2026 ;5(1): 2627062

A New biosensor illuminates the driving force behind mitochondrial outer membrane rupture.

Wei-Hua Chu, Wei-Chung Chiang.

  In PINK1 (PTEN induced kinase 1)/PRKN (Parkin)-mediated mitophagy, the rupture of the outer mitochondrial membrane (OMM) emerges as a crucial event required for efficient mitochondrial clearance. Mechanistically, OMM rupture exposes inner mitochondrial membrane (IMM) mitophagy receptors, facilitating subsequent autophagic removal. Despite the important role of OMM rupture in mitophagy, the underlying mechanism remains elusive and technically difficult to monitor. In a recent study, we developed a novel fluorescent biosensor to directly visualize OMM rupture. This technique enables temporal and spatial characterization of OMM rupture and provides a powerful platform to dissect the underlying mechanism. Using this tool, we revealed that VCP (valosin containing protein) and its recruitment factors are required for OMM rupture, suggesting that VCP-dependent remodeling of the OMM proteome primes the rupture of OMM during mitophagy. Abbreviations: ARIH1, Ariadne RBR E3 ubiquitin protein Ligase 1; AMFR, autocrine motility factor receptor; ANKRD13A, ankyrin repeat domain-containing protein 13 A; FUNDC1, FUN14 domain containing 1; OA, oligomycin and antimycin; CID, chemical-induced dimerization; IMM, nner mitochondrial membrane; LC3, microtubule-associated protein 1 light chain 3; MUL1, mitochondrial E3 ubiquitin protein ligase 1; NIX, BCL2 interacting protein 3 like; OMM, outer mitochondrial membrane; UBXN1, ubiquitin regulatory X domain-containing protein 1; UBXN6, ubiquitin regulatory X domain-containing protein 6; VCP, valosin-containing protein; WIPI2, WD repeat domain phosphoinositide interacting protein 2.

Keywords:  Biosensor; Mitochondrial outer membrane rupture; Mitochondrial quality control; PINK1/Parkin-mediated mitophagy; VCP

DOI:  https://doi.org/10.1080/27694127.2026.2627062
Autophagy. 2026 Feb 16. 1-16

Alphaherpesvirus UL48 homologs degrade STING1 by selective autophagy.

Zhengjie Kong, Xueke Sun, Xueying Zhai, Shuai Fan, Ruijing Liu, Wenjing Hu, Kaifeng Guan, Yifeng Zhang, Wenrui He, Yuhang Zhang, Bo Wan, Ning Li, Zhengjie Kong, Gaiping Zhang.

  Alpha-herpesviruses have evolved strategies to break through immune defenses and cause severe host damage. Here, we demonstrate that the tegument protein UL48 in pseudorabies virus (PRV) inhibits type I interferon signaling by triggering STING1 degradation via a selective macroautophagy/autophagy pathway. Mechanistically, UL48 recruits the E3 ligase TRIM21 (tripartite motif containing 21), which catalyzes the ubiquitination of STING1 to form a K33/K63 linkage and is captured by the cargo receptor CALCOCO2/NDP52 for lysosomal degradation. In addition, multiple α-herpesvirus tegument protein UL48 homologs also target STING1 for degradation. Importantly, this phenotype was also observed in other herpesviruses driven by PRV UL48 homologs (herpes simplex virus-1 [HSV-1] and cercopithecine alphaherpesvirus 2 [CHV-2]). In addition, UL48-deficient PRV and HSV-1 mutant viruses attenuated pathogenicity in mice. In conclusion, this study describes a novel mechanism by which α-herpesviruses utilize UL48 proteins to promote viral escape from the host immune response.Abbreviations: 3-MA: 3-methyladenine; B-DNA: poly (dA:dT); BNIP3L/Nix: BCL2 interacting protein 3 like; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; cGAMP: cyclic GMP-AMPP; CGAS: cyclic GMP-AMP synthase; CHX: cyclohexane; CHV-2: cercopithecine herpesvirus 2; CQ: chloroquine; DAPI: 4',6-diamidino-2-phenylindole; DMSO: dimethyl sulfoxide; ER: endoplasmic reticulum; GFP: green fluorescent protein; H&E: hematoxylin and eosin; HSV-1: herpes simplex virus 1; IRF3: interferon regulatory factor 3; LIR: LC3-interacting region; MAP1LC3A/LC3: microtubule associated protein 1 light chain 3 alpha; MG132: cbz-leu-leu-leucinal; NBR1: NBR1 autophagy cargo receptor; OPTN: optineurin; PRV: pseudorabies virus; sgRNA: single guide RNA; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; STING1/STING: stimulator of interferon response cGAMP interactor 1; TBK1: TANK binding kinase 1; TOLLIP: toll interacting protein.

Keywords:  CALCOCO2; CGAS-STING1; immune evasion; pseudorabies virus; selective autophagy; tegument protein UL48

DOI:  https://doi.org/10.1080/15548627.2026.2614901
Front Med (Lausanne). 2025 ;12 1735826

Mechanistic insights into non-coding RNAs regulate autophagy in chondrocytes and their contribution to osteoarthritis.

Bo Wang, Zhihong Wang.

  Osteoarthritis (OA), a chronic degenerative joint disease, arises from a confluence of factors including aging, mechanical injury, and obesity. Autophagy, a fundamental cellular process involving the degradation and recycling of cellular components, plays a critical role in chondrocyte homeostasis and survival under stress. Non-coding RNAs (ncRNAs), a diverse class of RNA molecules with no protein-coding potential, exert significant influence on gene expression through post-transcriptional and epigenetic mechanisms. Growing evidence suggests a crucial interplay between ncRNAs, autophagy, and OA pathogenesis. This review summarizes the multifaceted role of autophagy in OA chondrocytes and delves into the regulatory mechanisms of ncRNAs on OA-associated autophagy, aiming to elucidate the intricate pathological network underlying OA development and identify novel therapeutic targets.

Keywords:  autophagy; non-coding RNAs; osteoarthritis; pathological network; therapeutic targets

DOI:  https://doi.org/10.3389/fmed.2025.1735826
Autophagy. 2026 Feb 19. 1-2

A switchable role of neuronal BNIP3L/NIX in mitochondrial fate: fission or finish.

Xinlei Mo, Xingxian Zhang, Xiangnan Zhang.

  BNIP3L/NIX is a mitophagy receptor highly expressed in the brain. Unlike most mitophagy receptors that are recruited to mitochondria only upon stress, BNIP3L constitutively localizes to the mitochondrial outer membrane, suggesting functions beyond stress-induced mitophagy. Here, we identify a non-mitophagic role of BNIP3L in neuronal physiology. Conditional deletion of Bnip3l in glutamatergic neurons of the basolateral amygdala selectively impairs contextual fear memory in mice, a phenotype rescued by both wild-type BNIP3L and a mitophagy-deficient BNIP3L mutant lacking the LC3-interacting region motif. Mechanistically, BNIP3L competitively binds AMP-activated protein kinase (AMPK), thereby relieving AMPK-dependent inhibitory phosphorylation of DNM1L/DRP1 (dynamin 1 like) at Ser637. This interaction promotes rapid mitochondrial fission, supporting synaptic energy availability during memory encoding. Together, these findings reveal a switchable function of BNIP3L in neurons, acting either to acutely regulate mitochondrial dynamics to meet energetic demand or to engage mitophagy when mitochondrial function becomes compromised.

Keywords:  BNIP3L/NIX; Basolateral amygdala; fear memory; mitochondrial dynamics; mitophagy

DOI:  https://doi.org/10.1080/15548627.2026.2634183
Acta Physiol (Oxf). 2026 Mar;242(3): e70160

Lysosome pH Dynamics in Physiology and Disease: Molecular Mechanisms and Therapeutic Insights.

Sonia Infante-Tadeo, Diane L Barber.

   BACKGROUND: An acidic lysosomal lumen (pH ~4.5) is essential for the degradative and signaling functions of this organelle, which serves as a central hub for cellular homeostasis. Lysosome pH (pHlys), however, is not static but dynamically regulated by the coordinated action of the V-ATPase, counterion fluxes, membrane composition, and nutrient-sensitive signaling networks.
PURPOSE: This review integrates recent advances in the molecular mechanisms regulating pHlys with emerging insights on how dysregulated pHlys contributes to pathologies in neurodegenerative disorders, lysosomal storage diseases, and cancers with changes in lumenal proteolytic activity and macromolecular degradation.
MAIN FINDINGS: We discuss how pHlys acts as both a sensor and effector in lysosome biology, shaping transcriptional responses, membrane trafficking, and stress adaptation. We also review tools to measure pHlys, ranging from fluorescent dyes to genetically encoded biosensors and nanomaterial-based probes, and evaluate their use in disease-modeling applications.
CONCLUSIONS: By highlighting pHlys as a nodal point in cellular functions, this review underscores the relevance of pHlys as a diagnostic marker and therapeutic target. Restoring pHlys in diseases offers translational potential to re-establish proteostasis and limit associated pathologies.

Keywords:  cancer; lysosomal signaling; lysosome pH; neurodegeneration; pHlys regulation

DOI:  https://doi.org/10.1111/apha.70160
Acta Crystallogr D Struct Biol. 2026 Mar 01.

Phosphatidylinositol transfer protein α binds microcolins in its open conformation.

Andrea Eisenreichova, Martin Klima, Tamas Balla, Evzen Boura.

  Phosphatidylinositol transfer proteins (PITPs) are essential lipid-binding proteins that regulate phosphoinositide signaling, membrane trafficking and autophagy through the transport of phosphatidylinositol and other phospholipids between intracellular membranes. Microcolin compounds have been identified as selective inhibitors of class I PITPs, revealing important roles of PITPs in Hippo signaling and autophagy. Here, we report the crystal structure of human PITPα in complex with microcolin H at 2.0 Å resolution. The structure enables a detailed description of the interaction between microcolin H and the lipid-binding cavity. Besides the expected covalent bond to the Cys94 residue, the structure also reveals an extensive network of hydrogen bonds, water bridges and hydrophobic interactions. Importantly, PITPα remains in the open conformation upon binding to microcolin H. Quantitative cavity analysis confirms that the microcolin-bound structure adopts a volume comparable to that of the unliganded PITPα and is markedly larger than that of the lipid-bound state. These findings demonstrate that microcolins selectively trap PITPα in an open conformation and provide a structural basis for their inhibitory mechanism. Furthermore, our results show that ligand binding can profoundly change protein conformation, which underscores the limitation of docking experiments.

Keywords:  PITPs; crystal structure; inhibitors; lipid transport

DOI:  https://doi.org/10.1107/S2059798326000872
Biotechnol J. 2026 Feb;21(2): e70196

CREG1 Attenuates Osteoarthritis Progression by Suppressing Chondrocyte Pyroptosis Through the PINK1/Parkin-Mediated Mitophagy Pathway.

Xianming Fei, Shuanggong Liu, Guangxu Song, Shuhang Dong, Ziyi Song, Wei Xu.

   BACKGROUND: Osteoarthritis (OA) is a progressive degenerative disorder driven by complex pathogenic mechanisms. Increasing evidence indicates that NLRP3 inflammasome-mediated chondrocyte pyroptosis contributes critically to OA progression. Cellular repressor of E1A-stimulated gene 1 (CREG1), a secreted glycoprotein involved in cellular homeostasis and lysosomal function, has not been well characterized in OA. This study aimed to investigate the role of CREG1 in OA and its underlying molecular mechanisms.
METHODS: Human knee OA cartilage samples were analyzed to evaluate the association between CREG1 expression and chondrocyte pyroptosis. An LPS/ATP-induced in vitro pyroptosis model was used to assess the effects of CREG1 on chondrocyte apoptosis, extracellular matrix (ECM) degradation, NLRP3 inflammasome activation, and PINK1/Parkin-dependent mitophagy. Cyclosporin A (CsA) was applied to inhibit mitophagy.
RESULTS: CREG1 expression was significantly reduced in OA cartilage and negatively correlated with chondrocyte pyroptosis. CREG1 silencing aggravated apoptosis and ECM degradation, promoted NLRP3 inflammasome activation, impaired mitophagy, and disrupted mitochondrial function. Conversely, CREG1 overexpression restored PINK1/Parkin-mediated mitophagy, improved mitochondrial homeostasis, and suppressed NLRP3 inflammasome activation. These effects were abolished by CsA treatment.
CONCLUSIONS: CREG1 protects against OA progression by suppressing NLRP3 inflammasome-driven chondrocyte pyroptosis through activation of PINK1/Parkin-dependent mitophagy, highlighting CREG1 as a potential therapeutic target.

Keywords:  CREG1; NLRP3 inflammasome; mitophagy; osteoarthritis; pyroptosis

DOI:  https://doi.org/10.1002/biot.70196
Signal Transduct Target Ther. 2026 Feb 19. 11(1): 64

Hyperglutaminolysis drives senescence and aging through arginine-mTORC1 axis activation.

Honghan Chen, Ning Huang, Weitong Xu, Yu Yang, Fangfang Wang, Hui Gong, Jiao Zhou, Haoran Tai, Tingting Zhao, Jian Zhang, Ying Li, Ge Liang, Minghai Tang, Jie Li, Ming Yang, Jin Liu, Xiaoli Huang, Hengyi Xiao.

The catabolism of glutamine is essential for living organisms, so that its first step, driven by glutaminase 1 (GLS1), generally referred to as glutaminolysis, plays important roles in physiological metabolism. However, the status and impact of glutaminolysis in pathological contexts such as aging and age-related diseases remain elusive. In this study, through metabolomics analysis and different aging models, we verified the hyperactivation status of glutaminolysis in senescent cells and aged Drosophila and mice, which we term "hyperglutaminolysis". We further confirmed the aging-promoting role of this hyperglutaminolysis by addition and removal intervention experiments. Intriguingly, a novel signaling axis connecting to senescence-associated persistent mTORC1 activation was found. This pathway begins with glutaminase-catalyzed production of ammonium and glutamate, which drives arginine biosynthesis and is subsequently sensed by CASTOR1, leading to persistent mTORC1 activation. The regulatory roles of two key enzymes within this cascade, GLS1 and argininosuccinate lyase (ASL), were specifically investigated and verified by cellular and in vivo experiments, including those using stress-promoted and naturally aged animals, combined with GLS1 and ASL knockdown, and multiple rounds of metabolite analysis. In conclusion, our work positions dysregulated glutaminolysis as a key driver of aging and delineates a previously unrecognized molecular cascade that directly links glutaminolysis, arginine biosynthesis, and mTORC1 activation. These findings significantly expand our understanding of the relationship between glutamine catabolism and aging and are valuable for identifying novel intervention targets aimed at mitigating aging-related processes.

DOI: https://doi.org/10.1038/s41392-026-02576-w
Biol Pharm Bull. 2026 ;49(2): 291-300

Ouabain Suppresses CD63 Loading into Extracellular Vesicles via Na+/K+-ATPase-Dependent Localization to Autophagosomes.

Haruki Adachi, Takeshi Yoshida, Reina E Itoh, Chitose Oneyama.

  Extracellular vesicles (EVs), including exosomes, mediate intercellular communication by transferring lipids, proteins, and nucleic acids. However, the mechanisms determining selective cargo loading into EVs remain poorly understood. Here, we identify the cardiac glycoside ouabain as a selective inhibitor of CD63 loading into EVs. Using a luciferase-based high-throughput assay with CD9- and CD63-tagged reporter cells, ouabain was found to specifically suppress CD63 loading into EVs without affecting CD9 loading into EVs. Ouabain, Na+/K+-ATPase inhibitor, did not suppress EV secretion but markedly decreased CD63 incorporation. Other cardiac glycoside with strong Na+/K+-ATPase inhibitory activity, such as bufalin, exhibited similar effects, whereas weak inhibitors did not. Ouabain induced the internalization of Na+/K+-ATPase (ATP1A1) with CD63, resulting in the disappearance of CD63 from the plasma membrane. Furthermore, ouabain activated autophagy and promoted the colocalization of CD63 with autophagosomes, thereby selectively inhibiting the loading of CD63 into EVs. These effects required both Na+/K+-ATPase-dependent endocytosis and autophagy, as rapamycin-induced autophagy alone did not remove surface CD63. Our findings reveal a previously unrecognized mechanism in which cardiac glycoside regulates EV cargo composition by coupling Na+/K+-ATPase-mediated endocytosis with autophagy. Given that endogenous and therapeutic cardiac glycosides are implicated in cardiovascular and cancer biology, this mechanism may broadly influence EV-mediated intercellular communication and represent a potential target for modulating EV functions.

Keywords:  CD63; Na+/K+-ATPase; autophagy; cardiac glycoside; extracellular vesicle

DOI:  https://doi.org/10.1248/bpb.b25-00715
Autophagy. 2026 Feb 15. 1-23

Phase separation of OPTN initiates mitophagy to orchestrate craniofacial bone mineralization.

Haojie Liu, Zhenyi Lu, Xinyu Zhang, Yan Wang, Xiao Ge, Simai Chen, Yumeng Shi, Jingjing Yan, Rongyao Xu, Junqing Ma, Shuyu Guo.

  Recently, mitophagy-mediated bone mineralization of mesenchymal stem cells has emerged as another bone formation pattern, but whether mitophagy-mediated bone mineralization shapes craniofacial development remains unknown. Here, we demonstrate that loss of OPTN, a keystone macroautophagy/autophagy receptor, impairs mitophagy and acidic calcium phosphate (ACP) transport in orofacial bone mesenchymal stem cells (OMSCs), leading to craniofacial bone mineralization defects. We substantiate that OPTN undergoes LLPS both in vitro and in vivo, driven by S173 phosphorylation within its intrinsically disordered N-terminal domain (NTD), facilitating the association of OPTN complexes with phagophore membranes. Additionally, the ubiquitin-binding domain (UBD) in OPTN's C-terminal domain (CTD) also promotes LLPS to recruit ubiquitin-modified mitochondria. Physiochemically, mutations at the conserved sites in human OPTN (S173A and D474N) disrupt the OPTN LLPS, as validated in mouse and zebrafish, thereby inhibiting mitophagy and impairing bone mineralization. Together, our findings reveal a new mechanism through which OPTN LLPS couples mitophagy-mediated mineralization to craniofacial bone development, highlighting its potential as a therapeutic target for treating orofacial malformations via modulation of mitophagy.Abbreviations: 1, 6HD: 1, 6-hexanediol; ACP: acidic calcium phosphate; ALP: alkaline phosphatase; ARS: Alizarin Red staining; BFR/BS: bone formation rate per bone surface; Baf-A1: bafilomycin A1; CCCP: carbonyl cyanide 3-chlorophenylhydrazone; CTD: C-terminal domain; dpf: days post-fertilization; EDS: energy dispersive spectroscopy; FL: full length; FRAP: fluorescence recovery after photobleaching; hpf: 24h post-fertilization; IDR: intrinsically disordered region; IHC: immunohistochemistry; LLPS: liquid-liquid phase separation; LC-MS/MS: liquid chromatography-tandem mass spectrometry; MAR: mineral apposition rate; MS/BS: mineralizing surface per bone surface; NTD: N-terminal domain; ODM: osteogenic differentiation medium; OMSCs: orofacial bone mesenchymal stem cells; OPTN: optineurin; P1: postnatal day 1; P21: postnatal day 21; PDB: Paget disease of bone; PTMs: post-translational modifications; qRT-PCR: quantitative real-time PCR; S173: serine 173; STK4: serine/threonine kinase 4; SEM: scanning electron microscopy; TMD: tissue mineral density; TEM: transmission electron microscopy; UBD: ubiquitin-binding domain; Ub: ubiquitin.

Keywords:  Bone mineralization; OPTN; craniofacial development; mitophagy; phase separation

DOI:  https://doi.org/10.1080/15548627.2026.2624745
Cell Rep. 2026 Feb 18. pii: S2211-1247(26)00056-2. [Epub ahead of print]45(3): 116978

Clec16a maintains definitive hematopoietic stem and progenitor cells via mitophagy.

Shuyang Cai, Qian Zhang, Qian Luo, Honghu Li, Yuchen Tao, Cong Feng, Ruxiu Tie, Xiangjun Zeng, Shuo Chen, Zijun Song, Anli Wang, Qi Hu, Jizhang Bao, Yang Su, Yirong Chen, Hao Xu, Kexin Hu, Ning Ding, Runfeng Ni, Rui Jin, Fan Wu, Xiaojing Li, Xinyi Yang, Yang Xu, He Huang, Jiahui Lu.

  Hematopoietic stem and progenitor cells (HSPCs) arise from hemogenic endothelium via the endothelial-to-hematopoietic transition (EHT), a process requiring precise mitochondrial quality control. Here, we identify Clec16a, an E3 ubiquitin ligase, as a conserved regulator of embryonic HSPC emergence. In zebrafish and HEK293T models, Clec16a is enriched in hemogenic endothelium, and its loss disrupts arterial identity, impairs EHT, and reduces lymphoid, erythroid, and myeloid lineages. Transcriptomic and proteomic analyses show that Clec16a deficiency compromises mitophagy by promoting aberrant K48-linked ubiquitination and proteasomal degradation of ATG5, leading to mitochondrial dysfunction and elevated reactive oxygen species. These findings establish Clec16a as an essential regulator linking ubiquitin signaling, mitophagy, and hematopoietic fate specification. Our study defines a mitophagy-dependent checkpoint that safeguards mitochondrial homeostasis during developmental hematopoiesis and provides insight into the metabolic control of hematopoietic disorders.

Keywords:  Atg5; CP: metabolism; CP: stem cell research; Clec16a; USP8; hematopoietic stem and progenitor cell; mitophagy; non-degradative ubiquitination; zebrafish

DOI:  https://doi.org/10.1016/j.celrep.2026.116978
J Chem Phys. 2026 Feb 21. pii: 075101. [Epub ahead of print]164(7):

A universal phase-plane model for in vivo protein aggregation.

Matthew W Cotton, Alain Goriely, David Klenerman, Georg Meisl.

Neurodegenerative diseases are driven by the accumulation of protein aggregates in the brain of affected individuals. The aggregation behavior in vitro is well understood and driven by the equilibration of a super-saturated protein solution to its aggregated equilibrium state. However, the situation is altered fundamentally in living systems, where active processes consume energy to remove aggregates. It remains unclear how and why cells transition from a state with predominantly monomeric protein, which is stable over decades, to one dominated by aggregates. Here, we develop a simple but universal theoretical framework to describe cellular systems that include both aggregate formation and removal. Using a two-dimensional phase-plane representation, we show that the interplay of aggregate formation and removal generates cell-level bistability, with a bifurcation structure that explains both the emergence of disease and the effects of therapeutic interventions. We explore a wide range of aggregate formation and removal mechanisms and show that phenomena such as seeding arise robustly when a minimal set of requirements on the mechanism are satisfied. By connecting in vitro aggregation mechanisms to changes in cell state, our framework provides a general conceptual link between molecular-level therapeutic interventions and their impact on disease progression.

DOI: https://doi.org/10.1063/5.0312752
F1000Res. 2025 ;14 1137

A guide to selecting high-performing antibodies for Optineurin (UniProt ID: Q96CV9) for use in western blot, immunoprecipitation, and immunofluorescence.

Vera Ruíz Moleón, Riham Ayoubi, Charles Alende, Maryam Fothouhi, Joel Ryan, Sara González Bolívar, Donovan Worrall, Thomas M Durcan, Claire M Brown, Vincent Francis, Peter S McPherson, Carl Laflamme.

  Optineurin (OPTN) is a multifunctional cytoplasmic adaptor protein implicated in maintaining neuronal homeostasis through its roles in selective autophagy, vesicle trafficking, and regulation of inflammatory signaling. Mutations in the OPTN gene are causally linked to several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and primary open-angle glaucoma. Here we have eight optineurin commercial antibodies for western blot, immunoprecipitation, and immunofluorescence using a standardized experimental protocol based on comparing read-outs in knockout cell lines and isogenic parental controls. These studies are part of a larger, collaborative initiative seeking to address antibody reproducibility issues by characterizing commercially available antibodies for human proteins and publishing the results openly as a resource for the scientific community. While the use of antibodies and protocols vary between laboratories, we encourage readers to use this report as a guide to select the most appropriate antibodies for their specific needs.

Keywords:  OPTN; Q96CV9; antibody characterization; antibody validation; immunofluorescence; immunoprecipitation; optineurin; western blot

DOI:  https://doi.org/10.12688/f1000research.169966.1
Front Genet. 2026 ;17 1771707

Molecular mechanisms underlying the lifespan and healthspan benefits of dietary restriction across species.

Jialin Fan, Yunpeng Xu.

  Dietary restriction (DR), defined as reduced caloric intake or selective limitation of specific nutrients without malnutrition, is one of the most robust interventions known to extend lifespan and healthspan across species. Studies from yeast to mammals demonstrate that DR elicits conserved genetic, transcriptional, and epigenetic programs that promote cellular maintenance and stress resistance. At the molecular level, DR engages evolutionarily conserved nutrient-sensing pathways, including insulin/IGF-1 signaling (IIS), the mechanistic target of rapamycin (mTOR), AMP-activated protein kinase (AMPK), and NAD+-dependent sirtuins, which converge on key transcription factors (TFs) and transcriptional coactivators (TCs) to coordinate metabolic and longevity-associated gene expression. Downstream, these pathways enhance autophagy and proteostasis, remodel mitochondrial function and redox balance, reshape immune and inflammatory networks, and induce epigenetic and transcriptional reprogramming. Recent work further highlights amino acid-specific sensing mechanisms, endocrine mediators such as fibroblast growth factor 21 (FGF21), the gut microbiome, circadian regulators, and nuclear pore-associated transcriptional plasticity as integral components of DR responses. Importantly, the physiological outcomes of DR are context dependent and influenced by genetic background, sex, age at intervention, and the type and duration of restriction. In this review, we summarize current knowledge on the genetic and molecular architecture underlying DR-induced longevity and health benefits across species, discuss implications for aging-related diseases, and outline future directions toward precision nutrition and safe translational strategies.

Keywords:  aging; diet restriction; healthspan; lifespan; longevity; mTOR

DOI:  https://doi.org/10.3389/fgene.2026.1771707
Autophagy. 2026 Feb 15.

Ferritinophagy and organ injury.

Ningning Shao, Hongzhi Yu, Xue Li, Minghui Han, Cheng Chen, Jialin Zhu, Yuanyuan Tang, Jinrui Dong, Huaiyong Chen.

  Ferritinophagy is a selective form of macroautophagy/autophagy that mediates the degradation of ferritin complexes, releasing stored iron, and maintaining intracellular iron homeostasis. Proper regulation of ferritinophagy is essential for cellular adaptation to metabolic stress, whereas dysregulation disrupts iron balance and contributes to pathological processes. Excessive ferritinophagy leads to iron overload and reactive oxygen species accumulation, driving oxidative stress, ferroptosis, and inflammation, which are key contributors to cellular injury and progressive organ dysfunction. Despite advances in our understanding of autophagy and ferroptosis, the specific role of ferritinophagy in organ-specific injury remains unclear. In this review, we provide a comprehensive overview of the molecular mechanisms of ferritinophagy and critically examine its emerging roles in the pathogenesis of injuries to the heart, liver, lungs, and kidneys. We further highlight the therapeutic potential of targeting ferritinophagy and propose future research directions aimed at harnessing this pathway for the treatment of organ injuries.

Keywords:  Cell death; inflammation; iron; lipid peroxidation; oxidative stress; therapeutic targets

DOI:  https://doi.org/10.1080/15548627.2026.2633246
J Lipid Res. 2026 Feb 13. pii: S0022-2275(26)00027-1. [Epub ahead of print] 101001

Lipidation as a post-translational code for protein liquid-liquid phase separation.

Soodabeh Abbasi Sani, Agnieszka Chytła, Martin Sztacho.

  Liquid-liquid phase separation has emerged as a central organizing mechanism that drives the formation of biomolecular condensates and enables cells to spatially and temporally coordinate metabolism, signaling, and gene expression. While the influence of post-translational modifications such as phosphorylation and ubiquitination on condensate behavior is well established, the contribution of lipidation, the covalent attachment of lipid moieties to proteins, to these processes has received far less attention. Lipidation dictates protein hydrophobicity, membrane affinity, and subcellular distribution, yet how these parameters influence LLPS and thereby modulate condensate dynamics remains unclear. We propose that lipidation operates as a molecular code that integrates membrane association with phase separation, thereby tuning the assembly, composition, and thus functional output of condensates. Extending this concept beyond classical membrane systems, we further suggest that nuclear phosphoinositides, particularly phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) may act as an unconventional lipid modifier that structures membrane-less nuclear compartments through a process termed PIPoylation. Drawing on recent findings, we outline how canonical covalent lipidations, including palmitoylation, myristoylation, prenylation, and phospholipidation, govern membrane nanodomain organization, autophagy, and nuclear condensate architecture. We discuss how covalent lipidation influences condensate wetting, membrane curvature, and lipid-protein demixing, and how PI(4,5)P2 metabolism links chromatin remodeling with transcriptional control via LLPS. Together, these mechanisms underscore lipidation as a crucial regulator of condensate-membrane communication across cellular compartments.

Keywords:  biomolecular condensates; cell signaling; lipid rafts; membrane organization; phosphoinositides; phospholipids; post-translational modifications; transcription

DOI:  https://doi.org/10.1016/j.jlr.2026.101001
Neuroscience. 2026 Feb 13. pii: S0306-4522(26)00111-9. [Epub ahead of print]599 52-64

Neuroprotective effects of idebenone in a zebrafish model of Parkinson's disease via regulating autophagy, mitigating apoptosis and oxidative stress.

Yanqing Zhang, Tianhao Liu, Xinjia Li, Siyu Liu, Xiaoran Zhu, Yanhong Ren, Rundong Han, Chen Sun, Kechun Liu, Meng Jin, Xiuna Ji, Xiuhua Li.

  Idebenone (IDE), an analog of ubiquinone, has demonstrated therapeutic potential across various neurodegenerative disorders. Clinically, IDE has been shown to exert neuroprotective effects in Parkinson's disease (PD), being capable of alleviating motor symptoms as well as reducing depressive and anxious moods. However, the mechanism of action of IDE in PD has not been fully elucidated. Thus, the present study aims to investigate the potential effects of IDE on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD models in zebrafish, as well as the underlying mechanisms involved. The results demonstrated that IDE alleviated MPTP-induced locomotor dysfunction, preserved dopaminergic (DA) neuronal integrity, and mitigated cerebrovascular degeneration. Biochemical and molecular analyses revealed that IDE significantly reduced intracellular reactive oxygen species (ROS) accumulation and neuronal apoptosis, increased the activity of antioxidant enzymes (SOD, GSH-Px), and decreased malondialdehyde (MDA) levels. Real-time quantitative PCR (RT-qPCR) showed that IDE upregulated the expression of antioxidant stress-related genes (nrf2, ho-1), and anti-apoptotic genes (pi3k, akt1, akt2), while modulated the expression of autophagy-related markers (prkn, pink1, park7, atg5, atg7, p62). Western blot (WB) assays confirmed that IDE enhanced autophagic flux by upregulating Beclin1 expression and the LC3-II/LC3-I ratio, and downregulating P62 expression. Importantly, intervention with the autophagy inhibitor chloroquine (CQ) reversed IDE-mediated improvement of motor deficits, indicating that autophagy activation is a key mechanism. Collectively, IDE exerts neuroprotection in MPTP-induced PD zebrafish by activating autophagy, alongside anti-oxidative and anti-apoptotic actions, providing experimental evidence for its therapeutic potential in PD.

Keywords:  Apoptosis; Autophagy; Idebenone; Oxidative stress; Parkinson’s disease; Zebrafish

DOI:  https://doi.org/10.1016/j.neuroscience.2026.02.016