bims-axbals 2026-05-10 papers

bims-axbals

Biomed News

on Axonal biology and ALS

Issue of 2026–05–10
24 papers selected by
TJ Krzystek

Mitochondrial mechanics nucleates axonal jamming and swelling.
RYR:ATP6V0A1 complexes couple ER-lysosome contact sites to dynamic autophagy control.
Predictive Cellular Signatures from Live Human Motor Neurons Distinguish TDP-43 ALS and Enable ALS Subtype Stratification.
When tau stalls the lysosome: decoupling trafficking and degradation in autophagy.
Molecular Modulation of the Crosstalk Between TDP-43 and SOD1.
Targeting the integrated stress response or Ataxin-2 alleviates neurodegeneration in PolyGR models of C9orf72 associated frontotemporal dementia and amyotrophic lateral sclerosis.
Mitochondrial mechanics nucleates axonal jamming and swelling.
Proteasomal-dependent CHK1 degradation leads to DNA damage accumulation in ALS cellular model systems.
Human adherent cortical organoids in a multi-well format.
Huntington's Disease Human Lateral Ganglionic Eminence Precursors Differentiate into Functionally Mature Medium Spiny Neurons Exhibiting Pathology.
Multimodal strategies for diagnosis, stratification, and therapeutic monitoring in ALS.
LRRK2 regulates ArfGAP1 membrane localization, activity and neuronal integrity via phosphorylation within its lipid-sensing ALPS2 motif.
Using iPSC models to examine neuron-glia interactions in neurodegenerative diseases.
Rapid, Growth Factor-Reduced Induction of Functional Neurons from hiPSCs.
Pridopidine Protects ALS Patient-Derived Neural Progenitor Cells via Sigma-1 Receptor Activation.
TMEM106B C-terminal fragments drive nucleocytoplasmic transport failure and TDP-43 mislocalization in the aging human brain.
ALS-FTD-linked CCNFS621G drives increased hippocampal astrocyte ramification and mitochondrial dysfunction and impairs motor neuron excitability.
Short RNA chaperones promote aggregation-resistant TDP-43 conformers to mitigate neurodegeneration.
The emerging role and therapeutic targeting of autophagy-lysosome pathway in the pathogenesis of Parkinson's disease.
Autophagy is required for dopaminergic axon development and confers their responsiveness to guidance cues.
A human iPSC-derived sensory neuron platform for high-throughput discovery of neuroprotectants against chemotherapy-induced peripheral neuropathy.
Super-resolution Spinning-Disk Confocal Microscopy Using Optical Photon Reassignment (SoRa).
Tracking Synaptic Vesicles in Live Neurons Using Single-Molecule Super-resolution Microscopy.
Unperturbed dye-based imaging of spontaneous synchronized calcium activity in iPSC-derived neuronal cultures.

bioRxiv. 2026 Apr 25. pii: 2026.04.23.720276. [Epub ahead of print]

Mitochondrial mechanics nucleates axonal jamming and swelling.

Patrick S Noerr, Ahmed A Abushawish, Gulcin Pekkurnaz, Padmini Rangamani.

Neuronal function requires precise spatial organization of mitochondria to meet localized energetic demand. However, the physical constraints governing mitochondrial transport in axons remain poorly defined. Bidirectional motor-driven trafficking inherently introduces the potential for collisions, but the implications of these interactions for transport failure and structural damage are not understood. Here, we develop an agent-based model that couples mitochondrial motility, morphology, and lifecycle dynamics to a deformable axonal boundary. We show that mitochondrial traffic jams emerge from a force balance between active propulsion and steric interactions, and that their severity is governed by organelle shape and mechanical properties. Elongated, mechanically rigid mitochondria remain aligned and are transported rapidly, whereas flexible, low-aspect-ratio mitochondria are prone to jamming and accumulation. Incorporating fission and fusion dynamics reveals that fission amplifies transport disruption by generating collision-prone populations, while fusion restores transport by producing anisotropic structures that navigate crowded environments more efficiently. Importantly, we find that sustained jamming generates mechanical stress on the axonal membrane, leading to deformation and swelling. Together, these results establish a physical framework linking mitochondrial dynamics to axonal integrity and provide testable predictions for how dysregulated fission-fusion balance can drive transport failure and structural pathology in neurons.
Significance: 2Axonal deformation is implicated in myriad neurodegenerative conditions. Mitochondrial transport disruption is inextricably linked to axonal deformation and disease progression. Mechanistic understanding of the interplay between mitochondrial transport and axon stability remains opaque. Here, we developed an agent-based model of mitochondrial transport through axons. We found that mitochondria, driven to-ward presynapses for energy supply and toward the soma for repositioning or recycling, can collide, jam, and accumulate within axonal segments. The severity of jamming is sensitive to mitochondrial density as well as mechanical and morphological properties. Further, we found a balance between lifecycle dynamics including fission and fusion is paramount to maintaining homeostatic transport. Lastly, we predict that accumulated mitochondria can deform the axonal membrane, thereby elucidating a direct mechanical link between mitochondrial transport disruption and axonal deformation.

DOI: https://doi.org/10.64898/2026.04.23.720276
Autophagy. 2026 May 05.

RYR:ATP6V0A1 complexes couple ER-lysosome contact sites to dynamic autophagy control.

Jens Loncke, Manon Callens, Geert Bultynck, Tim Vervliet.

  Ryanodine receptors (RYRs) are ER-resident Ca2 + -release channels enriched in excitable cells, including neurons. RYR hyperactivity is implicated in early pathogenesis of disorders such as Alzheimer's disease (AD), which is associated with impaired autophagy. We recently uncovered a mechanism linking RYR activity to lysosome availability for autophagy. RYRs localize to ER - lysosome contact sites via direct binding to ATP6V0A1, a V-ATPase subunit that also suppresses RYR-mediated Ca2 + release. In human iPSC-derived cortical neurons, spontaneous RYR activity promotes lysosomal secretion, depleting the intracellular lysosomal pool and inhibiting autophagic flux. RYR inhibition promotes ER - lysosome contacts, limits lysosomal secretion, and restores lysosome availability for autophagosome fusion and cargo degradation (including APP). Conversely, disrupting the RYR:ATP6V0A1 interaction using a RYR-derived protein fragment serving as a "decoy" for ATP6V0A1 evokes RYR hyperactivity and stimulates lysosomal secretion. In this Punctum, we discuss how this RYR2:ATP6V0A1 "contact-site hub" may be perturbed in disease and highlight open questions on how lysosomes decode RYR-derived Ca2 + signals.

Keywords:  Calcium signaling; V-type ATPase; endoplasmic reticulum; lysosome; membrane contact site; ryanodine receptor

DOI:  https://doi.org/10.1080/15548627.2026.2669981
bioRxiv. 2026 Apr 24. pii: 2026.04.22.719920. [Epub ahead of print]

Predictive Cellular Signatures from Live Human Motor Neurons Distinguish TDP-43 ALS and Enable ALS Subtype Stratification.

Julia Kaye, Naufa Amirani, Úna Chan, Noura Al Bistami, Zohreh Faghihmonzavi, Monika Ahirwar, Reuben Thomas, Wesley Robinson, Edward Vertudes, Krishna Raja, Mariya Barch, Drew Linsley, Ana Jovicic, Steven Finkbeiner.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the progressive, rapid deterioration of motor neurons (MNs). Rare mutations in a handful of genes are sufficient to cause ALS; however, 90% of ALS cases are not linked to these genes and their underlying cause remains unknown. Abnormal subcellular distribution, structure or aggregation of the TDP-43 protein are nearly universal hallmarks of the disease, suggesting a shared molecular mechanism across both genetic and sporadic ALS (sALS). However, the heterogeneity of the ALS clinical syndrome suggests that the underlying mechanisms culminating in ALS and TDP-43 pathology may partly differ among individuals and may need to be understood to develop successful therapies that target subgroups of patients. Here, we harnessed the power of machine learning (ML) to begin to decode, in a systematic and unbiased fashion, the cellular signatures of ALS. We used high-content imaging of live, human iPSC-derived motor neurons (iMNs) from ALS patients or gene-edited and gene-corrected TDP-43 mutant lines to train shallow connected ML algorithms (SMLs) and deep convolutional neural networks (DNNs). Our models identified and distinguished mutant and control iMNs with moderately high accuracy. We then used explainability methods to uncover the discriminating cellular signals and found that the strongest ones mapped to the nuclear area, suggesting underlying alterations within the nucleus. We validated this finding by revealing that TDP-43 mutant iMNs display alterations in nucleocytoplasmic shuttling and cellular integrity. Further, a time-interaction ML model uncovered dynamic morphological transitions preceding degeneration, offering a window into early pathogenic events as well as neurodevelopmental changes. Extending our ML pipeline to iMNs with mutations in the ALS gene C9orf72 or derived from sALS revealed both overlapping and distinguishable signatures, suggesting shared yet distinct mechanistic pathways. Together, these findings establish ML-driven phenotypic profiling as a powerful approach to stratify people with ALS, help disentangle the molecular heterogeneity of ALS and produce a more holistic phenotypic definition in cell-based models, and ultimately find causes and treatments. This strategy offers a scalable and innovative paradigm for uncovering early disease mechanisms not only in ALS but potentially across a spectrum of neurodegenerative and sporadic disorders.

DOI: https://doi.org/10.64898/2026.04.22.719920
Autophagy. 2026 May 06. 1-3

When tau stalls the lysosome: decoupling trafficking and degradation in autophagy.

Celeste M Karch, Farzaneh S Mirfakhar.

  Tauopathies are characterized by the accumulation of misfolded tau and lysosomal dysfunction, yet whether defects in the autophagy-lysosome pathway are causal or secondary remains unclear. Recent work using human iPSC-derived neurons harboring the MAPT p.R406W mutation demonstrates that pathogenic tau is sufficient to disrupt lysosomal function upstream of tau accumulation. Tau species are differentially processed within lysosomes, with phosphorylated tau retained at the lysosomal membrane, consistent with a barrier to efficient cargo processing. Importantly, pharmacologic activation of autophagy restores degradative capacity and reduces tau burden without rescuing lysosomal motility, suggesting that trafficking and degradation represent separable axes of lysosomal biology. These findings position tau as an active disruptor of proteostasis and define a degradative bottleneck that shares features with lysosomal storage disorders. Together, this work reframes autophagy dysfunction in tauopathy as a modular defect with distinct therapeutic entry points.

Keywords:  Induced pluripotent stem cells; MAPT; lysosomal trafficking; neurons; tauopathy

DOI:  https://doi.org/10.1080/15548627.2026.2669685
Int J Mol Sci. 2026 Apr 10. pii: 3409. [Epub ahead of print]27(8):

Molecular Modulation of the Crosstalk Between TDP-43 and SOD1.

Gabriela D Ribeiro, Daniela D Queiroz, José R Monteiro-Neto, Ellen Gerhardt, Gabriel F de Souza, Paola C S C Albino, Luan H Paranhos, Tiago F Outeiro, Elis C A Eleutherio.

  Glycation of superoxide dismutase 1 (SOD1) has been shown to modulate the cytosolic levels of phosphorylated TAR DNA-binding protein 43 (TDP-43), a hallmark of amyotrophic lateral sclerosis (ALS) pathology. In this study, we investigated the interaction between TDP-43 and SOD1 and assessed how methylglyoxal (MGO)-induced glycation and the ALS-associated G93A SOD1 mutation affect this interplay in H4 cells. MGO exposure reduced SOD1 activity and TDP-43 phosphorylation in cells expressing WT SOD1, but not in those expressing G93A SOD1. Both WT and mutant SOD1 interacted with TDP-43 in the nucleus and cytosol; however, cytosolic interactions were more prevalent in G93A-expressing cells. Although MGO did not significantly alter the overall interaction between TDP-43 and WT SOD1, it induced cytosolic inclusion formation at 0.4 mM, a concentration associated with reduced cell viability. These inclusions did not colocalize with stress granules, indicating alternative aggregation pathways. Treatment with cyclosporin A, which inhibits the phosphatase calcineurin, decreased both TDP-43-WT SOD1 inclusions and cytosolic interactions between TDP-43 and G93A SOD1. Together, these findings suggest that SOD1 damage, induced by glycation or ALS-linked mutation, may affect TDP-43 phosphorylation status and promote its cytosolic mislocalization and aggregation, providing new insights into ALS-associated proteinopathy.

Keywords:  SOD1; TDP-43; amyotrophic lateral sclerosis; glycation; proteinopathy

DOI:  https://doi.org/10.3390/ijms27083409
Acta Neuropathol Commun. 2026 May 05.

Targeting the integrated stress response or Ataxin-2 alleviates neurodegeneration in PolyGR models of C9orf72 associated frontotemporal dementia and amyotrophic lateral sclerosis.

Nikki S Harper, Joanne L Sharpe, Jasmine Speranza, Ravinder Gulia, Jeffrey X Chen, Scott P Allen, Manpreet S Atwal, Stuart Pickering-Brown, Matthew R Livesey, Craig L Bennett, Andreas Prokop, Albert R La Spada, Ryan J H West.

  Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are fatal, early-onset neurodegenerative diseases. The most common genetic cause of FTD and ALS is a G4C2 hexanucleotide repeat expansion in the C9orf72 gene. This mutation leads to the production of toxic dipeptide repeat proteins (DPRs), via repeat-associated non-AUG (RAN) translation. These DPRs disrupt stress granule (SG) dynamics, with SG regulators such as Ataxin-2 (ATXN2) implicated in disease risk. The integrated stress response (ISR), a key driver of SG formation via eIF2α phosphorylation, has been linked to C9orf72 expansions, but the role of individual DPRs in ISR activation remains unclear. Here, using Drosophila models expressing physiologically relevant repeat length DPRs, we identify poly(GR) as a novel activator of the ISR, inducing early and sustained eIF2α phosphorylation and SG accumulation prior to motor decline. Genetic inhibition of the ISR or knockdown of ATX2, the Drosophila orthologue of ATXN2, rescues motor deficits in these models. ATXN2 knockdown also reduces poly(GR) toxicity in mouse primary neurons. These findings position poly(GR) as a key driver of ISR activation and highlight ATXN2 and the ISR as promising therapeutic targets in C9orf72-associated FTD/ALS.

Keywords:   Drosophila ; Amyotrophic lateral sclerosis; Ataxin-2; C9orf72; Frontotemporal dementia; Integrated stress response; Motor neurone disease; Stress granules

DOI:  https://doi.org/10.1186/s40478-026-02301-2
ArXiv. 2026 Apr 23. pii: arXiv:2604.22024v1. [Epub ahead of print]

Mitochondrial mechanics nucleates axonal jamming and swelling.

Patrick S Noerr, Ahmed A Abushawish, Gulcin Pekkurnaz, Padmini Rangamani.

Neuronal function requires precise spatial organization of mitochondria to meet localized energetic demand. However, the physical constraints governing mitochondrial transport in axons remain poorly defined. Bidirectional motor-driven trafficking inherently introduces the potential for collisions, but the implications of these interactions for transport failure and structural damage are not understood. Here, we develop an agent-based model that couples mitochondrial motility, morphology, and lifecycle dynamics to a deformable axonal boundary. We show that mitochondrial traffic jams emerge from a force balance between active propulsion and steric interactions, and that their severity is governed by organelle shape and mechanical properties. Elongated, mechanically rigid mitochondria remain aligned and are transported rapidly, whereas flexible, low-aspect-ratio mitochondria are prone to jamming and accumulation. Incorporating fission and fusion dynamics reveals that fission amplifies transport disruption by generating collision-prone populations, while fusion restores transport by producing anisotropic structures that navigate crowded environments more efficiently. Importantly, we find that sustained jamming generates mechanical stress on the axonal membrane, leading to deformation and swelling. Together, these results establish a physical framework linking mitochondrial dynamics to axonal integrity and provide testable predictions for how dysregulated fission-fusion balance can drive transport failure and structural pathology in neurons.
Cell Death Dis. 2026 May 06.

Proteasomal-dependent CHK1 degradation leads to DNA damage accumulation in ALS cellular model systems.

Stefania Modafferi, Valentina Silenzi, Anna Garbelli, Gloria Lazoi, Eveljn Scarian, Sara D'Uva, Tiziana Santini, Adelaide Riccardi, Mauro Cozzolino, Orietta Pansarasa, Nadia D'Ambrosi, Simone Sabbioneda, Mariangela Morlando, Sofia Francia.

Amyotrophic lateral sclerosis (ALS) is characterised by the aggregation of TDP-43 and mutant FUS in the cytoplasm of affected motor neurons. Accumulation of DNA damage is emerging as a novel correlative trait of ALS. We recently showed that formation of TDP-43 and FUS cytoplasmic inclusions (CIs) lead to DNA damage accumulation through dysregulation of the DNA damage response (DDR). However, the multiple molecular mechanisms contributing to DNA damage accumulation in affected motor neurons in ALS have not been fully elucidated. In recent years, chemical inhibition of the serine/threonine kinase CHK1 was shown to lead to accumulation of DNA breaks as well as increased apoptosis, in differentiated cortical neurons. Notably, CHK1 has been involved in DNA double-strand break repair in non-dividing cells, by acting through the histone chaperone ASF1A. In this article, we show that cells bearing FUS and TDP-43 CIs show downregulation of the protein levels of CHK1 and ASF1A. We observe CHK1 protein downregulation in neuronal cell lines, as well as in patient-derived motor neurons progenitors and in the spinal cord of a FUS-ALS mouse model. Restoration of the nuclear levels of CHK1 and ASF1A via transient overexpression, is sufficient to reduce DNA damage signal accumulation and rescues DDR defects. Importantly, we show that the ubiquitin-proteasome pathway is responsible for CHK1 degradation in cells bearing FUS CI, since its inhibition restores CHK1 and ASF1A protein levels. Our study demonstrates that proteasomal-dependent CHK1 and ASF1A downregulation contributes to accumulation of DNA damage in cells affected by ALS-linked protein aggregates.

DOI: https://doi.org/10.1038/s41419-026-08603-6
Elife. 2026 May 05. pii: RP98340. [Epub ahead of print]13

Human adherent cortical organoids in a multi-well format.

Mark van der Kroeg, Sakshi Bansal, Maurits A Unkel, Hilde Smeenk, Steven A Kushner, Femke M S de Vrij.

  In the growing diversity of human induced pluripotent stem cell (iPSC)-derived models of brain development, we present here a novel method that exhibits 3D cortical layer formation in a reproducible topography of minimal dimensions. The resulting adherent cortical organoids (ACOs) develop by self-organization after seeding frontal cortex-patterned iPSC-derived neural progenitor cells in 384-well plates during 8 weeks of differentiation. The organoids have stereotypical dimensions of 3 × 3 × 0.2 mm, contain multiple subtypes of neurons, astrocytes, and oligodendrocyte lineage cells, and are amenable to extended culture for at least 10 months. Longitudinal imaging revealed morphologically mature dendritic spines, axonal myelination, and robust neuronal activity. Moreover, ACOs compare favorably to existing free-floating brain organoid models on the basis of robust reproducibility in obtaining topographically standardized radial cortical structures and circumventing internal necrosis. Adherent human cortical organoids hold considerable potential for high-throughput drug discovery applications, neurotoxicological screening, and mechanistic pathophysiological studies of brain disorders.

Keywords:  brain organoids; disease modeling; human; neural differentiation; neuroscience; regenerative medicine; stem cells

DOI:  https://doi.org/10.7554/eLife.98340
Stem Cells. 2026 May 06. pii: sxag025. [Epub ahead of print]

Huntington's Disease Human Lateral Ganglionic Eminence Precursors Differentiate into Functionally Mature Medium Spiny Neurons Exhibiting Pathology.

Amy McCaughey-Chapman, Bronwen Connor.

  Huntington's disease (HD) is an autosomal dominant neurodegenerative disease characterised by the loss of GABAergic medium spiny neurons (MSNs). Cellular models of HD are mainly derived from human embryonic stem cells or induced pluripotent stem cells. These models are limited by their DNA embryonic age, low neuronal yields and limited disease pathology. We propose direct reprogramming, which maintains the aging signature of the cells, to human induced lateral ganglionic eminence precursors (hiLGEP) results in the generation of high yields of functionally mature MSNs exhibiting pathological hallmarks of HD. hiLGEPs were derived from normal and HD fibroblasts by direct reprogramming and differentiated to MSNs. hiLGEP and MSN fate acquisition was compared between normal and HD through gene and protein expression. Known pathological hallmarks of HD were investigated within the hiLGEP-derived MSNs. The formation of functional synapses was investigated using live cell calcium imaging. We demonstrate that HD fibroblasts can be reprogrammed to hiLGEPs expressing key linage markers and displaying disease-related changes in expression of FOXP1 and FOXP2. HD hiLGEPs can be differentiated to high yields of MSNs co-expressing DARPP32, GABA, or GAD65/67, and SYN1 and PSD-95. HD MSNs show a reduced expression of BDNF, HAP1, TRKB, Rhes and PGC1α, exhibit MW8+ mHTT aggregates and display smaller cell somas, reduced total neurite length and reduced branched neurites when compared to normal MSNs. An administration of 100 µM dopamine was necessary to generate a calcium response in HD MSNs. This study establishes a directly reprogrammed hiLGEP-derived MSN model of HD which recapitulates pathological signatures.

Keywords:  BDNF; Direct cell reprogramming; Huntington’s disease; human induced lateral ganglionic eminence precursor cells; medium spiny striatal neurons

DOI:  https://doi.org/10.1093/stmcls/sxag025
Neurosci Biobehav Rev. 2026 May 06. pii: S0149-7634(26)00184-3. [Epub ahead of print] 106727

Multimodal strategies for diagnosis, stratification, and therapeutic monitoring in ALS.

Rafael López-Blanch, María Oriol-Caballo, José M Estrela, Elena Obrador.

  Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder of motor neurons (MN) that is currently diagnosed through a prolonged process of exclusion, often delaying intervention. This review provides an overview of fluid, imaging, electrophysiological, and genetic biomarkers, explicitly linking each modality to early detection, patient stratification, disease monitoring, therapeutic development, and clinical trial design. Fluid biomarkers (i.e., neurofilament light chain, phosphorylated neurofilament heavy chain, inflammatory cytokines, microRNAs, and proteins in blood or cerebrospinal fluid) reflect neuronal injury and/or disease activity, enabling early identification of pres-ymptomatic individuals and longitudinal tracking of neurodegeneration. Imaging biomarkers, such as structural and diffusion MRI of the motor cortex, corticospinal tracts, and spinal cord, as well as PET imaging neuroinflammation or metabolism, provide objective measures of MN degeneration and extra-motor involvement. Electrophysiological biomarkers, including high-density electromyography, motor unit number, transcranial magnetic stimulation, and electrical impedance myography, quantitatively assess upper and lower MN loss and functional reserve. Genetic biomarkers, encompassing variants in genes such as C9orf72, SOD1, FUS, and TARDBP, enable presymptomatic screening and molecular stratification. In this context, transposable elements have emerged as an additional layer linking genomic variation and RNA dysregulation. We highlight the importance of multimodal and stage-specific biomarker integration to improve diagnostic accuracy and illuminate distinct disease phases. This approach supports stratification by progression rate or molecular subtype, enrichment of clinical trial cohorts, and the development of surrogate endpoints. We conclude by discussing current challenges, including disease heterogeneity and assay standardization, and outline future directions toward biomarker-driven precision medicine in ALS.

Keywords:  Amyotrophic lateral sclerosis; biomarkers; motor neuron; neurodegeneration; precision medicine

DOI:  https://doi.org/10.1016/j.neubiorev.2026.106727
Front Mol Neurosci. 2026 ;19 1786336

LRRK2 regulates ArfGAP1 membrane localization, activity and neuronal integrity via phosphorylation within its lipid-sensing ALPS2 motif.

Md Shariful Islam, Valentin Cóppola-Segovia, Alessandra Musso, Darren J Moore.

   Introduction: Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene cause late-onset, autosomal dominant Parkinson's disease (PD). LRRK2 encodes a multi-domain protein containing a Roc GTPase domain and a serine/threonine-directed protein kinase domain, with PD-linked mutations known to enhance LRRK2 kinase activity and neuronal toxicity. Our previous studies identified the Golgi protein, ADP-Ribosylation Factor GTPase-Activating Protein 1 (ArfGAP1), as a novel modifier of LRRK2-induced cellular toxicity, where it can serve as a GAP-like protein and a robust kinase substrate of LRRK2.
Methods: Here, we further explore the phosphorylation of ArfGAP1 by LRRK2 and its functional consequences.
Results: LRRK2 mediates the robust phosphorylation of ArfGAP1 in vitro within its lipid-sensing ALPS2 motif at residues Ser284, Thr291, and Thr292. We mutated these three candidate phosphorylation sites, either alone or combined, to create hydrophobic phospho-null or charged phospho-mimicking versions of ArfGAP1. We find that modulating ArfGAP1 phosphorylation at these sites impairs its normal capacity to induce Golgi fragmentation upon overexpression in neural cells. Blocking phosphorylation impairs ArfGAP1-induced neurite outgrowth inhibition in primary neurons and protects against the pathogenic effects of PD-linked G2019S LRRK2. ArfGAP1 interactome analysis in neural cells identifies 114 putative interacting proteins with a proportion of these localized to mitochondria, including the outer membrane proteins Voltage-Dependent Anion Channel (VDAC) 1-3. An ArfGAP1 triple phospho-mimic mutant displays an increased interaction with mitochondrial VDACs owing to the redistribution of ArfGAP1 from the cis-Golgi to the cytoplasm. Mimicking ArfGAP1 phosphorylation also blocks the formation of Golgi-derived vesicles following mild ER stress.
Discussion: Our data provides evidence for a complex functional interaction between LRRK2 and ArfGAP1 that serves to regulate ArfGAP1 subcellular localization, protein interactions, activity and neuronal integrity via LRRK2-mediated phosphorylation of its membrane-binding ALPS2 motif. Our findings support additional validation of ArfGAP1 as a putative therapeutic target for modulating LRRK2-linked PD.

Keywords:  ArfGAP1; Golgi; LRRK2; mitochondria; phosphorylation

DOI:  https://doi.org/10.3389/fnmol.2026.1786336
Biosci Rep. 2026 May 20. pii: BSR20250131. [Epub ahead of print]46(5):

Using iPSC models to examine neuron-glia interactions in neurodegenerative diseases.

Dianne M Lopez, Lois K Keavey, Kathryn R Bowles.

  Neurodegenerative diseases remain without effective or accessible treatments and interventions, despite their increasing global burden. Clinically, these disorders are characterised by progressive cognitive decline, behavioural changes, and loss of motor function, all of which are associated with neuronal and synaptic loss or dysfunction. Although traditionally viewed as neuron-centric, it is becoming increasingly clear that glial cells play critical roles in maintaining and regulating neuronal and synaptic health. Mounting evidence implicates glial dysregulation in both the onset and progression of neurodegenerative diseases through mechanisms such as aberrant synaptic engulfment and protein clearance, impaired homeostatic support, metabolic dysfunction, chronic inflammation, transmission of pathogenic proteins, and cellular senescence. Elucidating how disruptions in neuron-glia interactions contribute to neuronal dysfunction is therefore essential for developing effective therapies. Induced pluripotent stem cell (iPSC)-based models provide a powerful platform to investigate these interactions in human-relevant systems. Here, we will discuss recent insights into the mechanisms contributing to neurodegenerative disease that have been gained specifically from modelling neuron-glia interactions in human iPSCs.

Keywords:  astrocytes; induced pluripotent stem cells; microglia; neurodegeneration; neurons

DOI:  https://doi.org/10.1042/BSR20250131
Cells Tissues Organs. 2026 May 04. 1-18

Rapid, Growth Factor-Reduced Induction of Functional Neurons from hiPSCs.

Natalie A Parker, Oluwadamilola E Kolawole, Zhixin Liao, Farsin S Syed, Kara E Moquin, Nisha R Iyer.

INTRODUCTION: Human induced pluripotent stem cells (hiPSCs) can be rapidly converted into neurons via Neurogenin-2 (NGN2) overexpression, but many protocols require costly reagents during the initial induction phase that may limit adoption by labs without routine neuronal differentiation experience. We developed a simplified, low-cost protocol using a tetracycline-inducible (TET-on) NGN2 system in minimal media to generate cortical neurons in as few as 6 days.
METHODS: KOLF2.1J hiPSCs were stably transfected with a TET-on NGN2 cassette using the nonviral PiggyBac system and induced with doxycycline in Essential 6 media with or without the Notch inhibitor DAPT. Neurogenesis was evaluated with immunocytochemistry (ICC) and RT-qPCR, and cultures matured in defined conditions were characterized by multielectrode array (MEA) recordings to assess functional maturation.
RESULTS: DAPT markedly improved hiPSC-to-neuron conversion efficiency, and yielded glutamatergic neurons expressing cortical markers. MEA recordings showed spontaneous activity by day 14 and synchronous network firing by day 35. Secondary PB transfection enabled Td-Tomato labelling of KOLF2.1J:pB-TO-NGN2 hiPSCs, allowing 24-hour live imaging of neurite outgrowth.
CONCLUSION: This streamlined, growth-factor-free workflow provides an accessible route for generating functional neurons from patient-derived hiPSCs, including in labs with limited hiPSC or neuronal culture experience.

DOI: https://doi.org/10.1159/000552324
Int J Mol Sci. 2026 Apr 14. pii: 3489. [Epub ahead of print]27(8):

Pridopidine Protects ALS Patient-Derived Neural Progenitor Cells via Sigma-1 Receptor Activation.

May Meltzer, Maya Shefler Zamir, Noam Tzuri, Andrew M Tan, Michal Geva, Michael R Hayden, Rachel G Lichtenstein.

  The sigma-1 receptor (S1R) is an endoplasmic reticulum (ER)-resident protein enriched at the mitochondria-associated ER membranes (MAMs) that supports ER homeostasis, preserves mitochondrial function, and enhances cell survival under stress. Disruptions of MAM integrity and prolonged ER stress are well-recognized pathological features of amyotrophic lateral sclerosis (ALS), contributing to motor neuron dysfunction and degeneration. In this study, we evaluated the protective effects of pridopidine, a highly selective and potent S1R agonist currently in clinical development for Huntington's disease (HD) and ALS, using neural progenitor cells (NPCs) derived from induced pluripotent stem cells (iPSCs) from a patient with sporadic ALS. Exposure of ALS NPCs to the ER stressor tunicamycin increased the ER stress markers binding immunoglobulin protein (BiP) and C/EBP homologous protein (CHOP), disrupted mitochondrial membrane potential, upregulated expression of the mitochondrial apoptotic marker, BAX, increased caspase-3 activation, and reduced cell viability. Pridopidine significantly attenuated tunicamycin-induced BiP and CHOP expression in a biphasic, dose-dependent manner (with maximal efficacy at 1 µM), consistent with the typical pharmacology of S1R agonists. Pridopidine restored mitochondrial membrane potential, reduced mitochondrial apoptotic signaling, shown by decreased BAX expression and caspase-3 activation, and improved survival of ALS-NPCs under ER stress. Co-treatment with the selective S1R antagonist, NE-100, attenuated these effects, supporting an S1R-mediated mechanism of action for pridopidine. Together, these results demonstrate that S1R activation by pridopidine mitigates ER-stress-induced mitochondrial dysfunction and cell loss in ALS-NPCs, resulting in enhanced survival of NPCs supporting the therapeutic potential of pridopidine in ALS.

Keywords:  Sigma-1 receptor; amyotrophic lateral sclerosis; endoplasmic reticulum stress; iPSC-derived neural progenitor cells; mitochondria-associated membranes; mitochondrial membrane potential; pridopidine

DOI:  https://doi.org/10.3390/ijms27083489
bioRxiv. 2026 Apr 27. pii: 2026.04.23.719939. [Epub ahead of print]

TMEM106B C-terminal fragments drive nucleocytoplasmic transport failure and TDP-43 mislocalization in the aging human brain.

Kedamawit Tilahun, Janani Parameswaran, Myles Dudley, Daniel Pun, Fuying Ma, Jessee Zhang, Tatiana Bold, Jie Jiang.

TMEM106B is a lysosomal membrane protein and major genetic modifier of multiple neurodegenerative diseases, including frontotemporal lobar degeneration, Alzheimer's disease, and amyotrophic lateral sclerosis. Proteolytically generated C-terminal fragments of TMEM106B assemble into amyloid fibrils that accumulate in the brains of individuals with neurodegenerative disease and in cognitively normal aged adults, yet how these fibrils produce neuronal dysfunction has remained unclear. Here, we show that cytosolic and lysosome-directed TMEM106B C-terminal fragments (CTF and gCTF) form detergent-insoluble amyloid aggregates, drive redistribution of endogenous TDP-43 from the nucleus to the cytoplasm, and accelerate neuronal death. Unbiased proximity proteomics identified the inner nuclear membrane LAP1-TorsinA axis as a fragment-specific interactome, and co-immunoprecipitation confirmed a direct physical interaction between gCTF and LAP1 that was not observed with full-length TMEM106B. Fragment expression disrupted Lamin B1 organization, mislocalized the nuclear import machinery KPNB1 and RanGAP1, and impaired importin-dependent nuclear transport in primary cortical neurons. Critically, neurons harboring endogenous TMEM106B fibrillar pathology in aged human frontal cortex exhibited the same phenotypes, namely disrupted Lamin B1 and LAP1 localization and cytoplasmic redistribution of TDP-43, whereas fibril-negative neurons from the same cases and younger control tissue retained intact nuclear envelope organization. These findings define TMEM106B proteinopathy as an upstream driver of nuclear envelope disruption and nucleocytoplasmic transport failure, linking a widespread feature of brain aging to a central mechanism of neurodegeneration.

DOI: https://doi.org/10.64898/2026.04.23.719939
J Neuroinflammation. 2026 May 02.

ALS-FTD-linked CCNFS621G drives increased hippocampal astrocyte ramification and mitochondrial dysfunction and impairs motor neuron excitability.

Liam Robinson, Dzung Do-Ha, Flora Cheng, Claire H Stevens, Rossana Rosa Porto, Madilyn Coles, Jamesha Subachandran, Predrag Kalajdzic, Joanna Lui, Rachelle Balez, Sonia Sanz Muñoz, Mauricio Castro Cabral-da-Silva, Tracey Berg, Marco Morsch, Leszek Lisowski, Rachel H Tan, Gaétan Burgio, Tim Karl, Albert Lee, Roger S Chung, Ian Blair, Lezanne Ooi.

  Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative diseases with overlapping pathology. Mutations in CCNF, encoding the E3 ubiquitin ligase, Cyclin F, can cause ALS, FTD, or both, even within the same family. Most prior studies of CCNFS621G have relied on overexpression systems, potentially confounding outcomes through disruption of endogenous Cyclin F. Here, we generated the first knock-in mouse model of endogenous CcnfS621G using CRISPR/Cas9. Heterozygous and homozygous CcnfS621G mice showed no motor decline or neuronal loss after 18 months, however immunohistochemistry revealed increased hippocampal astrocyte ramification, with sex-, age, and subfield-dependent effects. These data indicate that endogenous CcnfS621G may prime early astrocyte alterations in the absence of overt neurodegeneration. Similar astrocyte morphological changes were observed in canonically affected regions of sporadic ALS and FTD-ALS patients post mortem, as well as in CCNFS621G iPSC-derived astrocytes following inflammatory stimulation. Proteomics on Ccnf mice identified early dysregulation of pathways related to translation, mitochondrial function, cytoskeletal remodelling, synaptic transmission and neuroinflammation. Correspondingly, CCNFS621G iPSC-derived astrocytes displayed impaired mitochondrial membrane potential and altered network morphology under both basal and inflammatory stimuli. As altered neuronal excitability is a hallmark of ALS, we examined astrocyte-driven changes to neuronal excitability. CCNFS621G iPSC-derived motor neurons cultured alone were hyperexcitable, firing more action potentials than isogenic controls. Remarkably, co-culture with CCNFS621G astrocytes, but not isogenic control astrocytes, abolished repetitive firing, increased the proportion of neurons unable to generate action potentials, and reduced voltage-gated sodium currents in CCNFS621G and isogenic control neurons. Together, these findings identify astrocyte alterations as an early feature of CCNFS621G-mediated disease, in the absence of neuronal loss. Moreover, the combination of astrocytic mitochondrial dysfunction and the ability of CCNFS621G astrocytes to suppress repetitive neuronal firing suggests a critical astrocyte-driven non-cell autonomous mechanism that may contribute to an oligogenic role for CCNF in ALS/FTD pathogenesis.

Keywords:   CCNF S621G ; ALS-FTD; Astrocyte dysfunction; CRISPR/Cas9 mouse model; Human post-mortem tissue; Mitochondrial dysfunction; Neurodegeneration; Neuronal excitability; iPSCs

DOI:  https://doi.org/10.1186/s12974-026-03827-x
Science. 2026 May 07. 392(6798): eadv3301

Short RNA chaperones promote aggregation-resistant TDP-43 conformers to mitigate neurodegeneration.

Katie E Copley, Jocelyn C Mauna, Helen L Danielson, Qizan Chen, Busra Ozguney, Marilyn Ngo, Longxin Xie, Ashleigh Smirnov, Matt Davis, Leland Mayne, Miriam Linsenmeier, Jack D Rubien, Cristian A Bergmann, Bede Portz, Bo Lim Lee, Hana M Odeh, Longsheng Lai, Yi-Wei Chang, Martina Hallegger, Jernej Ule, Piera Pasinelli, Yan Poon, Jeetain Mittal, Nicolas L Fawzi, Ben E Black, Christopher J Donnelly, Brigid K Jensen, James Shorter.

Aberrant aggregation of the prion-like RNA binding protein TDP-43 drives several fatal neurodegenerative proteinopathies, including amyotrophic lateral sclerosis (ALS). In this work, we define how short, specific RNAs solubilize TDP-43. These short RNAs engage and stabilize the TDP-43 RNA recognition motifs, which allosterically destabilizes a conserved helical region in the prion-like domain, thereby promoting aggregation-resistant conformers. Sequence-space mining identified short RNA chaperones with enhanced activity against TDP-43 and disease-linked variants. Enhanced short RNA chaperones mitigated aberrant TDP-43 phenotypes in optogenetic models and in ALS patient-derived and control motor neurons. In mice with cytoplasmic TDP-43 aggregation and motor neuron loss, an enhanced short RNA chaperone reduced pathological aggregation, restored TDP-43 function, and conferred neuroprotection. These results define a mechanistic and therapeutic framework for RNA-based strategies to counter TDP-43 proteinopathies.

DOI: https://doi.org/10.1126/science.adv3301
Transl Neurodegener. 2026 May 07. pii: 21. [Epub ahead of print]15(1):

The emerging role and therapeutic targeting of autophagy-lysosome pathway in the pathogenesis of Parkinson's disease.

Takahiro Shimizu, Sanem Isik, Nitika Kamath, Zhenyu Yue.

  Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by dopaminergic neuron loss and the accumulation of misfolded α-synuclein, yet the underlying mechanisms remain incompletely understood. Over the past two decades, genetic discoveries have highlighted the convergence of multiple familial PD genes on the autophagy-lysosome pathway (ALP), a key cellular system responsible for the degradation and recycling of intracellular components. Recent studies have further revealed that components of the ALP not only mediate the clearance of α-synuclein aggregates but also, under certain pathological conditions, contribute to their propagation via lysosomal exocytosis or secretory autophagy. The precise functions of autophagy are highly context-dependent, with neuronal and glial cells exhibiting distinct ALP dynamics that shift with development, stress, and aging. In this review, we summarize current knowledge on the physiological regulation of autophagy in the brain and critically examine its involvement in PD pathogenesis, incorporating mechanistic insights from familial models and emerging evidence from sporadic PD. We also explore translational implications, focusing on efforts to identify ALP-related biomarkers in cerebrospinal fluid and urine, and on the therapeutic potential of modulating ALP activity. Although the causality between ALP dysfunction and PD remains elusive, mounting evidence supports its contribution to disease progression, particularly through impaired lysosomal homeostasis and disrupted intracellular trafficking. Future research should aim to define cell type-specific ALP alterations, clarify the bidirectional interactions between α-synuclein and autophagic machinery, and develop in vivo tools to monitor autophagy activity and secretory signatures. A deeper understanding of these processes will be crucial for refining PD models, discovering robust fluid biomarkers, and designing targeted therapies capable of modifying disease trajectory.

Keywords:  Autophagy-lysosome pathway; Lysosomal homeostasis; Parkinson’s disease; Secretory autophagy; α-Synuclein

DOI:  https://doi.org/10.1186/s40035-026-00555-3
J Neurosci. 2026 May 07. pii: e1224252026. [Epub ahead of print]

Autophagy is required for dopaminergic axon development and confers their responsiveness to guidance cues.

Marcos Schaan Profes, Charles Gora, Flavie Lavoie-Cardinal, Armen Saghatelyan, Martin Lévesque.

Midbrain dopamine (mDA) neurons play a wide range of brain functions, but the molecular mechanisms driving the formation of mDA circuits remain largely unknown. Here, we show that autophagy, the main cellular recycling pathway, is present in the growth cones of developing mDA neurons, and its level changes dynamically in response to guidance cues. To characterize the role of autophagy in mDA axon growth and guidance, we knocked out essential autophagy genes (Atg12, Atg5) specifically in mDA neurons in mice of either sex. Autophagy-deficient mDA axons exhibit axonal swellings and reduced branching both in vitro and in vivo. Strikingly, deletion of autophagy-related genes completely blunted the response of mDA neurons to both chemorepulsive and chemoattractive guidance cues. Our data demonstrate that autophagy plays a central role in regulating mDA neuron development by orchestrating axonal growth and guidance.Significance Statement Midbrain dopaminergic neurons form circuits essential for movement, motivation, and cognition, yet the intracellular mechanisms controlling their axon growth and guidance remain poorly understood. Here we show that autophagy, a major cellular recycling pathway, operates locally in dopaminergic growth cones and is dynamically regulated by guidance cues. Using neuron-specific deletion of core autophagy genes, we demonstrate that autophagy is required for proper axonal morphology, branching, and responsiveness to both chemoattractive and chemorepulsive signals. These findings identify autophagy as a key regulator of dopaminergic circuit formation and reveal a previously unrecognized mechanism linking intracellular degradation pathways to axon guidance during brain development.

DOI: https://doi.org/10.1523/JNEUROSCI.1224-25.2026
Cell Rep Med. 2026 May 06. pii: S2666-3791(26)00204-1. [Epub ahead of print] 102787

A human iPSC-derived sensory neuron platform for high-throughput discovery of neuroprotectants against chemotherapy-induced peripheral neuropathy.

Veselina Petrova, Caitlin E Mills, Clemens Hug, Aysel Cetinkaya-Fisgin, Jennifer Splaine, Sepideh Fouladzadeh, Sara Hakim, Rasheen Powell, Shannon Zhen, Mirra Chung, Gary A Bradshaw, Tao Deng, Ilyas Singec, Qing Wang, Riki Kawaguchi, Harathi Jonnagaddala, Lee B Barrett, Jennifer A Smith, Marian Kalocsay, Benjamin M Gyori, Ahmet Hoke, Peter K Sorger, Clifford J Woolf.

  Chemotherapy-induced peripheral neuropathy (CIPN) is a major dose-limiting side effect of cancer treatment, yet the lack of predictive human models continues to hinder therapeutic progress. Here, we establish a scalable and reproducible model of paclitaxel-induced axon degeneration and neurotoxicity in human iPSC-derived sensory neurons, suitable for high-throughput identification of neuroprotective compounds. Using this platform, we screen a library of 192 kinase inhibitors and identify 19 hits that commonly inhibit three STE20 kinases-MAP4K4, MINK1, and TNIK. Genetic knockdown studies reveal that multi-kinase inhibition of these kinases is required for neuroprotection against paclitaxel. Consistently, selective pharmacological inhibition of the identified STE20 kinases rescues paclitaxel-induced axon degeneration in iPSC-derived sensory neurons and primary human dorsal root ganglia (DRG) and preserves intraepidermal nerve fiber density in a mouse model of CIPN. Together, these findings establish a translational human sensory neuron platform that enables target validation and drug discovery for CIPN.

Keywords:  STE20 kinases; axon degeneration; chemotherapy-induced peripheral neuropathy; high-throughput screening; iPSC-derived sensory neurons; neuroprotective small molecules

DOI:  https://doi.org/10.1016/j.xcrm.2026.102787
Methods Mol Biol. 2026 ;3034 29-43

Super-resolution Spinning-Disk Confocal Microscopy Using Optical Photon Reassignment (SoRa).

Sevannah A Steeves, Saber H Saber, Mo Chen, Frédéric A Meunier.

  Super-resolution spinning-disk confocal microscopy with optical photon reassignment (SoRa) is an advanced imaging technique that extends fluorescence microscopy resolution beyond the diffraction limit without the need for specialized sample preparation or intensive computational processing. By enhancing both lateral and axial resolution while preserving the rapid imaging speed of conventional spinning-disk systems, SoRa is particularly well suited for live-cell imaging and high-throughput studies. In contrast to other super-resolution approaches, SoRa enables fast, 3D imaging with low phototoxicity, making it ideal for capturing dynamic cellular events in real time. This chapter highlights the use of SoRa for two key applications: (1) high-throughput screening, specifically for assessing drug effects on neuronal processes such as dendritic outgrowth, and (2) high-resolution 3D imaging of live-cells including imaging mitochondrial trafficking in neurons. SoRa's versatility, speed, and compatibility with standard dyes make it a powerful tool for a wide range of biological and drug discovery research.

Keywords:  Confocal microscopy; Live imaging; Mitochondrial trafficking; Neurons; Super-resolution

DOI:  https://doi.org/10.1007/978-1-0716-5268-8_3
Methods Mol Biol. 2026 ;3034 189-209

Tracking Synaptic Vesicles in Live Neurons Using Single-Molecule Super-resolution Microscopy.

Shanley F Longfield, Frédéric A Meunier.

  Neurotransmitter release relies on the regulated fusion of synaptic vesicles (SVs) that are densely packed within the presynaptic bouton of neurons. The mechanisms by which SVs are clustered at the presynapse while dynamically organizing themselves into different SV pools with distinct fusion probabilities remain unknown. The study of SVs has historically been limited to ultrastructural studies of the presynapse. Examining the nanoscale dynamic organization of SVs in live neurons requires the use of innovative optical labelling approaches, super-resolution microscopy techniques, and appropriate stimulation paradigms that can mimic neuronal physiology. In this chapter, we discuss these aspects by highlighting the use of single-particle tracking photoactivated localization microscopy (sptPALM) to resolve the mobility and clustering of the total pool of SVs, Universal Point Accumulation Imaging in Nanoscale Topography (uPAINT) to study the mobility of SV proteins transiting on the plasma membrane, Dual-pulse subdiffractional Tracking of Internalized Molecules (DsdTIM) to simultaneously track the reserve and recycling pool of SVs and electrical field stimulation for depolarizing primary neurons.

Keywords:  Electric field stimulation; Endocytosis; Exocytosis; Fluorescence microscopy; Nanobodies; Presynapse; Single particle tracking; Synaptic vesicles; TIRF microscopy

DOI:  https://doi.org/10.1007/978-1-0716-5268-8_9
iScience. 2026 May 15. 29(5): 115689

Unperturbed dye-based imaging of spontaneous synchronized calcium activity in iPSC-derived neuronal cultures.

Nina Dirkx, Bob Asselbergh, Peter Verstraelen, Jonas Van Lent, Els De Vriendt, Vincent Timmerman, Winnok H De Vos, Sarah Weckhuysen.

  Synchronous calcium (Ca2+) bursting is a hallmark of neuronal network maturation. While microelectrode array (MEA) recordings are routinely used to generate population-averaged measurements on this functional network activity, live cell Ca2+-imaging offers single-cell resolved, contextual data. Unfortunately, most electrophysiologically active cells are hypersensitive to medium exchange, which is standard practice in most sensor dye-based Ca2+-imaging protocols. Here, we found that the use of conditioned imaging medium preserves spontaneous network activity of iPSC-derived glutamatergic and motor neuron cultures. The effect was consistent across different cell lines and seeding densities and allowed for the faithful detection of disease-specific phenotypes, as shown using a KCNQ2-related epilepsy model. Our findings thus provide a simple, robust strategy to measure spontaneous network activity in Ca2+-imaging experiments, broadening the utility of this technique for functional phenotyping, disease modeling, and drug screening with cellular resolution.

Keywords:  imaging methods in chemistry; neuroscience

DOI:  https://doi.org/10.1016/j.isci.2026.115689