bims-axbals Biomed News
on Axonal biology and ALS
Issue of 2025–12–07
eighteen papers selected by
TJ Krzystek
  1. Protective or Pathogenic? Kinase activity and the neurodevelopmental origins of G2019S LRRK2-Associated Parkinson's disease.
  2. TDP-43 promotes efficient HSV-1 replication in human DRG-derived neurons.
  3. A guide to selecting high-performing antibodies for Heterogeneous nuclear ribonucleoproteins A2/B1(hnRNP A2/B1) (UniProt ID: P22626) for use in western blot, immunoprecipitation, and immunofluorescence.
  4. C9orf72-related amyotrophic lateral sclerosis-frontotemporal dementia and links to the DNA damage response: a systematic review.
  5. LRRK2 integrates Rab and GABARAP interactions to sense and respond to distinct lysosomal stresses.
  6. Differential regulation of p62-ubiquitin conjugates in neurons versus astrocytes during cellular stress.
  7. The Vap33 signaling axis precisely coordinates the timing of motoneuron dendritogenesis in neural map development.
  8. Loss of Nuclear TDP-43 Impairs Lipid Metabolism in Microglia-Like Cells.
  9. Human TDP-43 overexpression in zebrafish motor neurons triggers MND-like phenotypes through gain-of-function mechanism.
  10. Development of a p62 biodegrader for autophagy targeted degradation.
  11. A distinct PP2A subunit regulates local protein phosphorylation at the axon initial segment.
  12. A system for high-throughput axonal imaging of induced pluripotent stem cell-derived human i3Neurons.
  13. Huntingtin protein in Health and Huntington's Disease: Molecular Mechanisms, Pathology and Therapeutic Strategies.
  14. Loss of ErbB3 redirects Integrin β1 from early endosomal recycling to secretion in extracellular vesicles.
  15. DLK orchestrates a modular transcriptional response to axon injury with separate roles for Fos and Jun.
  16. Live-cell Imaging of Lysosomal Membrane Permeabilization During Necroptosis.
  17. VAPB is a negative regulator of STING-mediated innate immune signaling.
  18. Navigating the Autophagy Maze: ATG and Their Impact on Neurodegenerative Diseases.
  1. Parkinsonism Relat Disord. 2025 Nov 25. pii: S1353-8020(25)00882-X. [Epub ahead of print] 108133
    Protective or Pathogenic? Kinase activity and the neurodevelopmental origins of G2019S LRRK2-Associated Parkinson's disease.
    Emilia M Gatto, Alberto J Espay, Melisa Espindola, Gustavo Da Prat, Marcelo A Kauffman.
      Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common monogenic cause of Parkinson's disease (PD), with the p.Gly2019Ser (G2019S) variant being particularly prevalent. The LRRK2 gene encodes a large, multi-domain protein (LRRK2) belonging to the Roco family, possessing both kinase and GTPase activities. Because normal LRRK2 function is critical for neuronal development, synaptic plasticity, vesicle trafficking, mitochondrial homeostasis, and neuroinflammatory pathways, pathogenic LRRK2 variants likely impair these functions. This is supported by rodent models and induced pluripotent stem cell (iPSC) studies suggesting that G2019S LRRK2 variants accelerate neuronal differentiation and disrupt synaptic function early in development, while kinase overactivity (phosphorylation of various substrates) is critical during normal embryonic growth. Contrary to the dominant gain-of-toxic-function hypothesis, these observations support an alternative loss-of-function framework, whereby increased kinase activity may be a compensatory cellular strategy to counteract the loss or alteration of the homeostatic and neurodevelopmental functions associated with G2019S LRRK2. If validated by further studies, including ongoing LRRK2 kinase inhibitor trials, future LRRK2-PD therapeutic strategies may shift from broad kinase inhibition toward individualized modulation of specific LRRK2-mediated impairments, such as vesicle trafficking, mitochondrial integrity, or microglial dysfunction. Such an approach would recognize LRRK2-PD not as a single entity but as a biologically heterogeneous group of PD subtypes.
    Keywords:  G2019S LRRK2; Mitochondrial dysfunction; Neurodegeneration; Neurodevelopment; Neuroinflammation; Parkinson's disease; Synaptic plasticity
    DOI:  https://doi.org/10.1016/j.parkreldis.2025.108133
  2. J Virol. 2025 Dec 04. e0091525
    TDP-43 promotes efficient HSV-1 replication in human DRG-derived neurons.
    Shirley E Braspenning, Denise Ohnezeit, Olivia A DeGulis, Angus C Wilson, Ian J Mohr.
      TAR DNA-binding protein 43 (TDP-43) is a versatile nuclear RNA-binding protein that performs important functions in RNA localization, processing, and stability. In the neurodegenerative disease amyotrophic lateral sclerosis (ALS) TDP-43 forms toxic, insoluble cytoplasmic aggregates that ultimately lead to neuronal loss. Although TDP-43 is expressed in every cell type, its function and subcellular localization are particularly important for neuronal homeostasis. However, it is unknown if TDP-43 has a role during herpesvirus infection. Herpes simplex virus type-1 (HSV-1), a ubiquitous neurotropic pathogen, is considered a contributing factor to neurodegenerative disorders. In this study, we tested the requirement for TDP-43 during HSV-1 infection in neuronal and non-neuronal cells. HSV-1 infection of epithelial cells and primary fibroblasts did not change overall TDP-43 abundance, nor did TDP-43 depletion detectably alter HSV-1 productive replication in a multicycle growth experiment. By contrast, when TDP-43 was depleted in neuronally-derived, differentiated HD10.6 cells, HSV-1 infectious virus production was significantly reduced in both single- and multicycle growth experiments. Notably, TDP-43 depletion restricts viral lytic gene expression at the immediate-early phase. Through nanopore direct RNA-sequencing, we uncovered enhanced intron retention in two essential viral genes-ICP0 and UL15-upon TDP-43 depletion. Thus, while depletion of TDP-43 does not detectably affect HSV-1 reproduction in epithelial cells and fibroblasts, TDP-43 is required for efficient replication in HD10.6 cells through modifying the abundance and splicing of viral mRNAs.IMPORTANCEHerpes simplex virus type-1 is a widespread neurotropic pathogen that can cause life-threatening infections of the brain and is increasingly linked to neurodegenerative disease. However, due to the lack of scalable in vitro human neuronal models or small animal models that recapitulate disease, little is known about virus-host interactions in neurons specifically. Using human epithelial cells, primary fibroblasts and a human neuron-derived cell line, we uncovered a cell type specific TDP-43 requirement for efficient HSV-1 virus replication. TDP-43 is a critical neuronal disease factor gene, and we showed it promotes HSV-1 gene expression and splicing of viral mRNAs in neuron-derived cells. This raises the possibility that targeting of TDP-43 could reveal a new antiviral strategy for severe HSV-1 infections. This work further provides valuable insights into the possible etiology of neurodegenerative disease and highlights the importance of studying virus-host interactions in relevant cell types.
    Keywords:  HSV-1; RNA splicing; TAR DNA-binding protein 43; direct RNA-sequencing; sensory neurons
    DOI:  https://doi.org/10.1128/jvi.00915-25
  3. F1000Res. 2025 ;14 1158
    A guide to selecting high-performing antibodies for Heterogeneous nuclear ribonucleoproteins A2/B1(hnRNP A2/B1) (UniProt ID: P22626) 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.
      Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) is a key RNA-binding protein involved in alternative splicing, mRNA transport, and local translation processes essential for neuronal development and synaptic plasticity. Here we have characterized eight hnRNP A2/B1 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:  HNRNPA2B1; Heterogeneous nuclear ribonucleoproteins A2/B1; P22626; antibody characterization; antibody validation; immunofluorescence; immunoprecipitation; western blot
    DOI:  https://doi.org/10.12688/f1000research.170886.1
  4. Front Mol Neurosci. 2025 ;18 1671906
    C9orf72-related amyotrophic lateral sclerosis-frontotemporal dementia and links to the DNA damage response: a systematic review.
    Seham Almalki, Mohamed Salama, Matthew J Taylor, Zubair Ahmed, Richard I Tuxworth.
      The G4C2 repeat expansion in C9orf72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). While healthy individuals have fewer than 30 repeats, affected patients may carry hundreds to thousands. This expansion accounts for approximately 40% of familial ALS and 25% of familial FTD cases, and between 5 and 10% cases of sporadic ALS and FTD. Three overlapping pathological mechanisms have been proposed for the C9orf72 expansion: loss of function due to protein deficiency, gain of function through RNA foci, and the production of toxic dipeptide repeat proteins (DPRs) via repeat-associated non-ATG (RAN) translation. This systematic review investigates the role of DNA damage in C9orf72-related ALS-FTD. Analysis of twelve peer-reviewed studies showed that C9orf72 repeat expansions and DPRs compromise genome stability across four experimental models: human cell lines, induced pluripotent stem cell-derived neurons, rodent neurons, and postmortem tissue. We identified four mechanisms underlying DNA damage accumulation: disruption of the ATM pathway, impairment of DNA repair efficiency, formation of R-loops, and mitochondrial dysfunction with oxidative stress. In addition, several consequences of DNA damage were identified, including misrepair-mediated repeat expansion and activation of STING pathway. These findings highlight the key role of DNA damage in C9orf72-related pathology. Consistent with this, targeting DNA damage response factors extended lifespan and improved motor function in mouse models. This review highlights the contribution of DNA damage to C9orf72 pathology and suggest new therapeutic avenues, including personalized approaches based on genetic background.
    Keywords:  ALS; ALS-FTD; C9orf72; DDR; DNA damage; DNA repair; FTD
    DOI:  https://doi.org/10.3389/fnmol.2025.1671906
  5. bioRxiv. 2025 Nov 19. pii: 2025.11.19.689251. [Epub ahead of print]
    LRRK2 integrates Rab and GABARAP interactions to sense and respond to distinct lysosomal stresses.
    Devin Clegg, Amanda Bentley-DeSousa, Agnes Roczniak-Ferguson, Shawn M Ferguson.
      Increased activity of leucine-rich repeat kinase 2 (LRRK2) is an important risk factor for Parkinson's disease. LRRK2 localizes to lysosomal membranes, and changes in lysosome physiology are emerging as key regulators of its activation, yet the mechanisms by which distinct perturbations engage this kinase remain unclear. Analysis of osmotic and membrane-integrity challenges revealed that LRRK2 integrates multiple upstream cues through parallel interactions with Rab GTPases and GABARAP. Manipulations that caused lysosome enlargement, including inhibition of PIKfyve, showed that osmotic swelling leads to the accumulation of multiple Rabs on lysosomes and Rab-dependent LRRK2 activation independently of GABARAP. In contrast, under conditions of lysosome deacidification, CASM-dependent lipidation of GABARAP creates a platform that cooperates with Rabs in LRRK2 activation. These findings demonstrate how LRRK2 interprets perturbations of lysosome function through a combination of Rab- and GABARAP-dependent mechanisms, providing a framework for understanding both normal physiological regulation and pathological dysregulation in Parkinson's disease.
    Significance Statement: This study reveals how LRRK2 integrates lysosomal stress signals through coordinated interactions with Rab GTPases and GABARAP. Osmotic swelling drives strong Rab-dependent activation, whereas deacidification requires CASM-mediated GABARAP lipidation as a scaffold for LRRK2 activation at lysosomes. These results define how LRRK2 activation at lysosomes is tuned across physiological and pathogenic contexts.
    DOI:  https://doi.org/10.1101/2025.11.19.689251
  6. bioRxiv. 2025 Nov 18. pii: 2025.11.17.688722. [Epub ahead of print]
    Differential regulation of p62-ubiquitin conjugates in neurons versus astrocytes during cellular stress.
    David K Sidibe, Erin M Smith, Maeve L Spivey, Maria C Vogel, Sandra Maday.
      Sequestosome 1/p62 (hereafter referred to as p62) is a multifunctional protein that orchestrates various cellular stress response pathways including autophagy, proteasome-mediated degradation, antioxidant defense, nutrient sensing, and inflammatory signaling. Mutations in distinct functional domains of p62 are linked with the neurodegenerative disease amyotrophic lateral sclerosis (ALS), underscoring its importance in neural cells. Neurons and astrocytes perform distinct roles in brain physiology and thus encounter a unique landscape of cellular stress. However, how p62 is regulated in these cell types in response to various stress modalities remains largely unexplored. Several functions for p62 depend on engagement with ubiquitinated substrates. Thus, we investigated how the regulation of p62-ubiquitin conjugates differs between neurons and astrocytes exposed to two stress modalities: lysosomal membrane damage and metabolic stress. Lysosomal damage triggered ubiquitin-dependent assembly of p62 puncta in both neurons and astrocytes. In contrast, nutrient deprivation elicited different responses between neurons and astrocytes. Neurons formed p62-ubiquitin structures more prominently and displayed a greater dependence on ubiquitin for p62 clustering. Together, these findings reveal cell-type-specific and stress-specific regulation of p62-ubiquitin conjugates, indicating that neurons and astrocytes can deploy distinct quality control strategies.
    DOI:  https://doi.org/10.1101/2025.11.17.688722
  7. Nat Commun. 2025 Dec 04. 16(1): 10893
    The Vap33 signaling axis precisely coordinates the timing of motoneuron dendritogenesis in neural map development.
    Daichi Kamiyama, Rie Kamiyama, Yuri Nishida, Anthony Sego, George Berner Vining, Kathy Clara Bui, Miyuki Fitch, Hy Gia Truong Do, Oshri Avraham, Takahiro Chihara.
      In Drosophila motoneurons, spatiotemporal dendritic patterns are established in the ventral nerve cord. While many guidance cues have been identified, the mechanisms of temporal regulation remain unknown. Previously, we identified the actin modulator Cdc42 GTPase as a key factor in this process. In this report, we further identify the upstream factors that activate Cdc42. Using single-cell genetics, FRET-based imaging, and biochemical techniques, we demonstrate that the guanine nucleotide exchange factor Vav is anchored to the plasma membrane via the Eph receptor tyrosine kinase, enabling Cdc42 activation. VAMP-associated protein 33 (Vap33), a potential Eph ligand supplied non-cell-autonomously, may induce Eph autophosphorylation, initiating downstream signaling. Traditionally known as an ER-resident protein, Vap33 is secreted extracellularly at the onset of Cdc42 activation, acting as a temporal cue. In humans, VAPB-the ortholog of Vap33-is similarly secreted in the spinal cord, and its dysregulation leads to amyotrophic lateral sclerosis type 8 (ALS8). Our findings may help inform future studies on how VAPB signaling contributes to motor circuit formation in both physiological and disease contexts.
    DOI:  https://doi.org/10.1038/s41467-025-65900-y
  8. Res Sq. 2025 Nov 20. pii: rs.3.rs-8036170. [Epub ahead of print]
    Loss of Nuclear TDP-43 Impairs Lipid Metabolism in Microglia-Like Cells.
    Khushbu Kabra, Dallin Dressman, Ryan Talcoff, Maedot Yidenk, Olivia M Rifai, Benjamin N Hoover, Neil A Shneider, Wassim Elyaman, Estela Area-Gomez, Elizabeth M Bradshaw.
      Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease marked by progressive motor neuron loss, with TDP-43 pathology present in over 90% of cases. While neuroinflammation is a recognized hallmark, the role of microglia in ALS pathogenesis remains incompletely understood. Here, we demonstrate that TDP-43 regulates microglial function via triglyceride metabolism. Using shRNA-mediated TARDBP knockdown in human monocyte-derived microglia-like cells (MDMi), we observed suppressed cholesterol biosynthesis, upregulated fatty acid uptake, lipid droplet accumulation, enhanced phagocytic activity, and increased IL-1β production. Inhibiting diacylglycerol acyltransferase (DGAT) enzymes reduced lipid droplet formation, phagocytosis, and IL-1β, directly linking the triglyceride pathway to microglial activation. Patient-derived MDMi from both sporadic and TARDBP -mutant ALS cases showed overlapping as well as distinct alterations, some of which were reversed by DGAT inhibition. Our findings identify dysregulated triglyceride metabolism as a novel pathway through which TDP-43 mediates microglial dysfunction, highlighting a potential therapeutic target for ALS.
    DOI:  https://doi.org/10.21203/rs.3.rs-8036170/v1
  9. Acta Neuropathol Commun. 2025 Dec 02.
    Human TDP-43 overexpression in zebrafish motor neurons triggers MND-like phenotypes through gain-of-function mechanism.
    Alison L Hogan, Madison Kane, Patrick Chiu, Grant Richter, Cindy Maurel, Sharlynn Wu, Natalie M Scherer, Emily K Don, Albert Lee, Ian P Blair, Roger S Chung, Marco Morsch.
      
    Keywords:  Alzheimer’s disease; Amyotrophic lateral sclerosis; Frontotemporal lobar dementia ; Motor neurons; Neurodegeneration; TDP-43; Zebrafish
    DOI:  https://doi.org/10.1186/s40478-025-02159-w
  10. Nat Commun. 2025 Dec 03. 16(1): 10858
    Development of a p62 biodegrader for autophagy targeted degradation.
    Zacharias Thiel, David Marcellin, Carole Manneville, Benedikt Goretzki, Luca Egger, Rob Maher, Noémie Siccardi, Laura Torres, Alexandra Probst, Catrin S Müller, Nathalie George, Markus Vogel, Sabine Sinterhauf, Alexandra Lavoisier, Ji-Young Choi, Laurianne Forcellino, Alexandro Landshammer, Patrick Hauck, Celine Be, Frédéric Villard, Sascha Gutmann, Marc Meyer, Felix Freuler, Alexandra Hinniger, César Fernández, Suzanne Chau, Maude Patoor, Gilles Sansig, Gabriel Mitchell, Beat Nyfeler.
      Autophagy-based targeted degradation offers a powerful complement to proteasomal degradation leveraging the capacity and versatility of lysosomes to degrade complex cargo. However, it remains unclear which components of the autophagy-lysosomal pathway are most effective for targeted degradation. Here, we describe two orthogonal induced-proximity strategies to identify autophagy effectors capable of degrading organelles and soluble targets. Recruitment of autophagy cargo receptors, ATG8-like proteins, or the kinases ULK1 and TBK1 is sufficient to trigger mitophagy, while only autophagy cargo receptors capable of self-oligomerization degrade soluble cytosolic proteins. We further report a single-domain antibody against p62 and its use as a heterobifunctional degrader to clear mitochondria. Fusing the p62 single-domain antibody to PINK1 enables selective targeting of damaged mitochondria. Our study highlights the importance of avidity for targeted autophagy and suggests that autophagy cargo receptors are attractive entry points for the development of heterobifunctional degraders for organelles or protein aggregates.
    DOI:  https://doi.org/10.1038/s41467-025-65868-9
  11. Nat Commun. 2025 Dec 03. 16(1): 10850
    A distinct PP2A subunit regulates local protein phosphorylation at the axon initial segment.
    Andrew P Anderson, Sanghyun Kim, Allison J Melton, Xiaoyun Ding, Wei Zhang, Alexander B Saltzman, Anna Malovannaya, Matthew N Rasband, Yudong Gao.
      Protein phosphorylation plays a crucial role in regulating the cytoskeletal and membrane proteins at the axon initial segment (AIS). However, our knowledge of AIS-specific kinases and phosphatases is very limited. Here, we report the identification of a protein phosphatase 2A (PP2A) B55 regulatory subunit enriched at the AIS in mice: Ppp2r2c. Our results demonstrate that PP2A-B55 subunits exhibit substantial heterogeneity in their subcellular localization and function. Notably, the Ppp2r2c subunit is selectively concentrated at the AIS, and this enrichment is driven by its unique structure. Utilizing a microelectrode array system (MEA), we show that Ppp2r2c modulates neuronal activity during in vitro development. With phosphoproteomics, we further reveal that the potassium channel Kv1.2 is one of the downstream targets that link Ppp2r2c activity to neuronal excitability. Together, these data provide a critical entry point for understanding the mechanisms of PP2A-mediated local phospho-regulation at the AIS.
    DOI:  https://doi.org/10.1038/s41467-025-66120-0
  12. Mol Biol Cell. 2025 Dec 03. mbcE25060300
    A system for high-throughput axonal imaging of induced pluripotent stem cell-derived human i3Neurons.
    Stella A C Whittaker, Elizabeth D McKenna, Stephanie L Sarbanes, Michael S Fernandopulle, Michael E Ward, Antonina Roll-Mecak.
      Neurons have long, thin axons and branched dendritic processes which rely on an extensive microtubule network that functions as a cellular scaffold and substrate for cargo transport. Microtubule defects are a defining pathological feature of neurological disorders. The highly arborized, long, polarized neuronal processes pose challenges for imaging-based assays. Available methods use either dispersed cultures, which are inefficient for compartment-specific analyses, or microfluidic chambers, which allow clear separation of somatodendritic and axonal compartments but are expensive and difficult to maintain. Here, we introduce an "i3Neurosphere" culture model of induced pluripotent stem cell (iPSC)-derived human cortical i3Neurons that enables high-throughput imaging of hundreds of axons without specialized equipment. We characterize neurite outgrowth, polarization, microtubule dynamics, and motility of diverse cargo, providing a reference for future work on microtubule processes in this system. The high-throughput compartment-specific imaging we present, combined with facile genetic engineering in i3Neurons provides a powerful tool to study human neurons. [Media: see text] [Media: see text] [Media: see text] [Media: see text].
    DOI:  https://doi.org/10.1091/mbc.E25-06-0300
  13. Ageing Res Rev. 2025 Dec 03. pii: S1568-1637(25)00330-7. [Epub ahead of print] 102984
    Huntingtin protein in Health and Huntington's Disease: Molecular Mechanisms, Pathology and Therapeutic Strategies.
    Rinku Shaha, Angel Godad.
      Huntington's Disease (HD) is a neurodegenerative, genetic disorder that affects the brain and is caused by the expansion of cytosine-adenine-guanine (CAG) trinucleotide in the huntingtin (HTT) gene exceeding 35 units. Further, the mutation occurs, which leads to the generation of mutant huntingtin (mHTT) protein, which is a toxic protein that damages the neurons and their functions, leading to disease progression. Phosphorylation, SUMOylation, O-GlcNAcylation, and ubiquitination are some of the post-translational modifications (PTMs) that affect the toxicity, location, and aggregation of this altered protein. The survival of neurons depends on autophagy, vesicle trafficking, transcriptional control, and mitochondrial function, all of which are disrupted by HTT. This protein tends to form aggregates, which disrupt vital neuronal functions and ultimately result in neuronal death, especially in the cortex and striatum. The three clinical manifestations of HD include mental health problems, cognitive impairment, and motor symptoms (bradykinesia, chorea). In this review, the HTT protein is examined, along with its normal functions, post-translational modifications, and role in HD pathogenesis. The therapeutic intervention under investigation includes PTM-targeted medications, which are those drugs that enhance neuroprotection and proteostasis, and gene silencing strategies such as antisense oligonucleotides and RNA interference. Disease models are being improved with several novel approaches, which include induced pluripotent stem cells (iPSCs) and CRISPR-based editing and preclinical models. By integrating these technologies, the mechanisms of the underlying disease have also been enhanced. The recent treatment approaches have also been explored by using molecular targets and diagnostic tools, including FANCD2 and FANCI-associated nuclease 1 (FAN1), which are genetic regulators of somatic CAG expansion; EPS8 dysregulation, which causes protein aggregation; and mismatch negativity (MMN), which is a brain response detected by EEG, a non-invasive biomarker for early cognitive impairment. These measures aim to slow down disease progression and improve the health and outcomes of patients.
    Keywords:  AMT-130; Autophagy; Huntington’s Disease; Oxidative phosphorylation; Polyglutamine expansion
    DOI:  https://doi.org/10.1016/j.arr.2025.102984
  14. J Cell Biol. 2026 Jan 05. pii: e202501255. [Epub ahead of print]225(1):
    Loss of ErbB3 redirects Integrin β1 from early endosomal recycling to secretion in extracellular vesicles.
    Dorival Mendes Rodrigues-Junior, Ana Rosa Sáez-Ibáñez, Takeshi Terabayashi, Nina Daubel, Taija Mäkinen, Olof Idevall-Hagren, Aristidis Moustakas, Ingvar Ferby.
      Receptor tyrosine kinases (RTKs) are important cargo in endocytic trafficking, yet their role in endosomal sorting and maturation of multivesicular bodies remains unclear. Here, we show that the ErbB3 (HER3) receptor sorts internalized Integrin β1 and the transferrin receptor, for endocytic recycling, in a manner that does not require ligand-induced ErbB3 signaling in breast epithelial cells. Loss of ErbB3 abrogates recycling of Integrin β1, likely from a Rab4-positive compartment, and redirects it toward lysosomal degradation or secretion as an extracellular vesicle (EV) cargo. ErbB3 depletion impairs the collective migration of breast epithelial cell sheets, coinciding with reduced cell-surface levels of Integrin β1 and increased release of Integrin β1-containing EVs. In contrast, EVs secreted from ErbB3-depleted cells enhance the motility of wild-type cells. Mechanistically, ErbB3 promotes assembly of the Arf6-GGA3-Rabaptin5 endosomal sorting complex to facilitate early recycling and suppress EV release. These findings provoke the notion that pseudo-RTKs play an active role in vesicular trafficking.
    DOI:  https://doi.org/10.1083/jcb.202501255
  15. PLoS Genet. 2025 Dec;21(12): e1011969
    DLK orchestrates a modular transcriptional response to axon injury with separate roles for Fos and Jun.
    Gibarni Mahata, Li Chen, Gregory O Kothe, Melissa M Rolls.
      Axon injury initiates transcriptional reprogramming that in competent cells leads to regeneration. In vertebrate neurons, DLK acts upstream of Jun, STAT and Atf3, core transcription factors that mediate regeneration. It is unclear whether these three proteins are activated independently, or whether they function in a linear cascade. To investigate relationships between these transcription factors we wished to use Drosophila as a model system as it has one ortholog of each. However, the only transcription factor linked to DLK-mediated axon regeneration (AR) in flies was Fos. Using loss of function approaches we demonstrate that Jun, STAT and Atf3 are required for Drosophila sensory axon regeneration, indicating transcriptional control of axon regeneration is broadly conserved. We next investigated temporal roles for Fos, Jun, STAT and Atf3. Only Fos is required for the early transcriptional response, which coincides with neuroprotection, and its nuclear entry and homodimerization coincide with this phase. Reduction of Jun homodimerization occurs after axon injury downstream of DLK/JNK, but independently from Fos, at a later stage associated with axon regrowth. STAT nuclear entry occurs downstream of Jun as part of this stage, is inhibited by Fos, and does not require JAK, which is dispensable for axon regeneration. Atf3 nuclear exit is in turn downstream of Fos, Jun, and STAT. Our results suggest that DLK/JNK separately activates Fos and Jun, and that Jun initiates a transcriptional cascade that includes STAT and Atf3. These two transcriptional modules control separate steps of the injury response that culminates in axon regeneration.
    DOI:  https://doi.org/10.1371/journal.pgen.1011969
  16. J Vis Exp. 2025 Nov 14.
    Live-cell Imaging of Lysosomal Membrane Permeabilization During Necroptosis.
    Katia S G Andrade, John Mably, Da-Zhi Wang, Zhigao Wang.
      Necroptosis, a form of regulated necrosis, culminates in cell membrane rupture. Our lab and others have discovered that lysosomal membrane permeabilization (LMP) is an early and crucial event in this process, preceding membrane rupture. Rapid LMP releases potent lysosomal enzymes, particularly proteases, into the cytosol, actively promoting cell death. Live-cell imaging provides an invaluable tool for detecting LMP during necroptosis in real-time. Several fluorescent dyes are highly effective: (1) pH-sensitive LysoTracker dyes track changes in lysosomal pH. A decrease in fluorescence signal indicates a loss of the lysosomal pH gradient, a primary sign of lysosomal dysfunction, which may be a precursor or direct consequence of LMP. (2) Fluorescein-labeled dextran beads are internalized and accumulate in lysosomes. Their release into the cytosol signals complete LMP and cargo leakage. Here, we observed a progressive loss of Lysotracker fluorescence, with diffusing Dextran fluorescence into the cytosol after necroptosis induction. Thus, the live-cell imaging methodology enables researchers to precisely track the timing and extent of lysosomal dysfunction, contributing to a more comprehensive understanding of necroptosis mechanisms and illuminating potential therapeutic interventions.
    DOI:  https://doi.org/10.3791/69495
  17. Sci Adv. 2025 Dec 05. 11(49): eaea3996
    VAPB is a negative regulator of STING-mediated innate immune signaling.
    Wangsheng Ji, Yin Zhang, Lianfei Zhang, Qingqing Liu, Shengbo Niu, Yuqun Feng, Feilong Chen, Xinqi Liu, Xia Li.
      Stimulator of IFN genes (STING) is an endoplasmic reticulum (ER) signaling receptor involved in the type I interferon response to pathogen- or self-derived cytosolic double-stranded DNA. Excessive activation of STING is associated with many diseases, but the regulatory mechanism of STING activation remains to be further elucidated. Here, we identify VAPB as a negative regulator of STING-mediated innate immune response. VAPB deficiency increases the expression of type I interferons under resting conditions or upon stimulation. Mechanistically, VAPB associates and translocates with STING, thereby regulating STING translocation, oligomerization, and recruitment of TBK1. In vivo, deficiency of VAPB enhances the expression of type I interferons and prevents lethality following HSV-1 infection. Furthermore, VAPB P56S, a pathogenic mutation causing amyotrophic lateral sclerosis (ALS), can promote STING-mediated innate immune response under resting conditions, which might contribute to further understanding of the relationship between cGAS-STING pathway and ALS. Our study identifies VAPB as a critical regulating factor in cGAS-STING-mediated innate immune responses.
    DOI:  https://doi.org/10.1126/sciadv.aea3996
  18. Mol Neurobiol. 2025 Dec 06. 63(1): 260
    Navigating the Autophagy Maze: ATG and Their Impact on Neurodegenerative Diseases.
    Roshanak Amirian, AmirHossein Merati, Mehregan Babamohamadi, Yasaman Mirahmadi, Mahsa Loran Esfahani, Shahla Rahmani, Zhila Izadi, Davood Rezazadeh.
      Autophagy, a tightly regulated process essential for maintaining cellular homeostasis, plays a critical role in the pathogenesis and progression of neurodegenerative diseases (NDs). These disorders-marked by diverse mechanisms and clinical heterogeneity-pose significant challenges in developing effective therapies. Central to the autophagic machinery are autophagy-related genes (ATGs), whose functions and variants are increasingly recognized as pivotal in modulating disease-specific pathways. This review explores the intricate roles of ATGs in NDs, emphasizing the need for a comprehensive understanding of molecular signaling networks, protein-protein interactions, and regulatory checkpoints that may serve as therapeutic targets. We highlight recent advancements in disease modeling, autophagy assays, and biomarker identification that facilitate the translation of ATG-related discoveries into clinical practice. Furthermore, we underscore the importance of interdisciplinary collaboration across academia, industry, clinical medicine, and regulatory bodies to harness the therapeutic potential of autophagy. This article aims to serve as a detailed roadmap for understanding the role of ATGs in NDs and to illuminate promising avenues for future research and therapeutic development.
    Keywords:  Alzheimer’s disease (AD); Amyotrophic lateral sclerosis (ALS); Autophagy; Autophagy genes (ATG); Huntington’s disease (HD); Neurodegenerative diseases (NDs); Parkinson’s disease (PD)
    DOI:  https://doi.org/10.1007/s12035-025-05332-3
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