bims-axbals 2026-03-01 papers

bims-axbals

Biomed News

on Axonal biology and ALS

Issue of 2026–03–01
34 papers selected by
TJ Krzystek

Autophagy induction mitigates FUS aggregate formation and early synaptic dysfunction at the NMJ in the FUS-ALS model.
TDP-43 pathology is linked to motor neuron loss but is independent of stress granules in vivo.
Tubulin acetylation governs organelle remodeling and lysosomal reformation during neuronal differentiation.
Neuronal Cell-Cycle Re-entry Defines Divergent Outcomes Through Replication-Dependent DNA Damage in ALS.
Neuronal TDP-43 regulates myelin formation via neurexin 1 mRNA stabilization.
Generation and characterization of human iPSC-derived NPC1 I1061T/I10161T i 3 Neurons as a model for NPC1 disease.
Antisense Dipeptide Repeat Proteins Drive Widescale Purine Metabolism Aberration in C9orf72 Amyotrophic Lateral Sclerosis via ADA.
Discovery of TDP-43 aggregation inhibitors via a hybrid machine learning framework.
Repeat expansions in C9orf72 rewire the 3D chromatin landscape in ALS.
Intrathecal (G 4 C 2 ) 149 delivery in C9orf72-deficient mice yields mild motor dysfunction and ALS/FTD pathological hallmarks.
Modeling spastic paraplegia 4 with corticospinal motor neuron-enriched cortical organoids reveals genotype-phenotype and HDAC6-targetable pathology.
Wild-type C9orf72 expression is a genetic modifier of C9-ALS survival.
Next questions of autophagy in neurodegenerative diseases: From mechanisms to therapeutics.
The endoplasmic reticulum in mitochondrial protein targeting: A neuronal perspective on organelle crosstalk.
A Robust Methodological Framework for Generating Whole-Brain and Cortical Organoids From Diverse Healthy- and Patient-Derived Induced Pluripotent Stem Cell Lines.
Temporal proteomic and phosphoproteomic dynamics during neuronal differentiation in the reference iPSC line KOLF2.1J.
Encephalopathy-linked UFM1 variants impede neuronal protein translation, development, and function.
Isolation and Quantification of Axonal mRNAs Using Porous Membrane Inserts and RTddPCR.
Reversing Mitochondrial Dysfunction in Optineurin E50K Glaucoma: A Metabolic Approach to Neuroprotection.
TRIM32-UBQLN2-p62 axis promotes TDP-43 inclusion formation and amyloid aggregation through shuttle condensates.
Autophagosome turnover requires Arp2/3 complex-mediated maintenance of lysosomal integrity.
Advances and Challenges in the Use of Spinal Cord Organoids in ALS.
Cdc5-mediated Ulp2 phosphorylation controls the timing of polySUMOylation during the cell cycle.
The DNA/RNA autophagy protein SIDT2 as a novel neuropathological hallmark in Huntington disease.
Stemness factor Mex3a times translation and protein trafficking to ensure robust differentiation of olfactory sensory neurons.
Ubiquitin ligase Nedd4 regulates the abundance and toxicity of mutant huntingtin.
Organelle communication networks rewire to support lipid metabolism during neuronal differentiation.
The Calcium Connection: Explaining Motor Neuron Vulnerability in ALS.
C9orf72-ALS mutation drives basal mitophagy impairments in iNeurons.
Role of nuclear import proteins in maintaining proteostasis and disease pathogenesis.
Clinical-Grade Human Induced Pluripotent Stem Cell-Derived Neural Precursor Cells Restore Motor Function and Preserve Striatal Integrity in a Quinolinic Acid-Lesioned Rat Model of Huntington's Disease.
Membrane Dysfunction as a Central Mechanism in LRRK2-Associated Parkinson's Disease: Comparative Analysis of G2019S and I1371V Variants.
CPEB3 selectively inhibits α-synuclein aggregation without modulating TDP-43 pathology.
Loss of calcium-binding protein Cbp53E leads to delayed repolarization of photoreceptor cells in Drosophila.

bioRxiv. 2026 Feb 20. pii: 2026.02.19.706635. [Epub ahead of print]

Autophagy induction mitigates FUS aggregate formation and early synaptic dysfunction at the NMJ in the FUS-ALS model.

Tulika Malik, Sam Jones, Olivia Ma, Sahana Mohan, R Michael Burger, Daniel T Babcock.

Mutations in Fused in Sarcoma (FUS), a RNA binding protein, cause Amyotrophic Lateral Sclerosis (ALS). ALS is an aggressive neurodegenerative disease resulting in motor neuron degeneration. Defects in synaptic integrity precede neuronal loss in ALS, but the mechanisms responsible for these early synaptic defects are unclear. To investigate early synaptic defects associated with ALS, we expressed an ALS-linked variant of human FUS in adult motor neurons and assessed synaptic pathology at the neuromuscular junction (NMJ). Here we highlight the accumulation of FUS-positive aggregates at synaptic terminals and subsequent reduction in microtubule stability. We show that inducing autophagy via expression of Rab1 or Fragile-X Mental Retardation Protein 1 (FMR1), or treatment with Rapamycin reduces aggregate formation and restores synaptic structure and function. These findings reveal the utility of inducing autophagy to address early synaptic dysfunction in an ALS model and demonstrate a potential therapeutic target to preventing later stages of disease progression.

DOI: https://doi.org/10.64898/2026.02.19.706635
bioRxiv. 2026 Feb 13. pii: 2026.02.11.705439. [Epub ahead of print]

TDP-43 pathology is linked to motor neuron loss but is independent of stress granules in vivo.

Alicia Dubinski, Ala Ferdi, Mariam Choughari, Holly Spence, Arpita Adhikary, Carolane Fauchon, Melissa Touati, Myriam Gagné, Martha Liu, Sarah Peyrard, Jenna Gregory, Christine Vande Velde.

Nuclear depletion and cytoplasmic aggregation of TDP-43 are pathological hallmarks of several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), Alzheimer's disease, and the recently defined limbic-predominant age-related TDP-43 encephalopathy (LATE). Chronic activation of the integrated stress response (ISR) and persistence of stress granules, phase-separated assemblies proposed to function as a protective mechanism, have been hypothesized to initiate the formation of pathological TDP-43 inclusions observed in post-mortem neurons. However, recent clinical trials targeting the ISR and stress granule dissolution failed to demonstrate clinical benefit despite robust target engagement, calling this model into question. Here, we employ a recurrent hyperthermia paradigm to directly examine the relationship between stress granules and TDP-43 pathology in vivo . We find that RNA-binding proteins classically associated with stress granules persist as phase-separated cytoplasmic structures in spinal motor neurons of both non-transgenic and mutant TDP-43 mice. Importantly, these structures are reversible and spatially distinct from TDP-43 puncta. Moreover, in a mutant TDP-43 mouse model with an impaired acute stress granule response, stress exposure induces TDP-43 nuclear export and cytoplasmic accumulation. Recurrent stress in these mice leads to a selective loss of spinal α-motor neurons. Together, our findings demonstrate that TDP-43 nuclear clearance and cytoplasmic demixing occur independently of stress granules in vivo , challenging prevailing models of TDP-43 pathogenesis and highlighting important implications for therapeutic strategies targeting the ISR.

DOI: https://doi.org/10.64898/2026.02.11.705439
bioRxiv. 2026 Feb 14. pii: 2026.02.13.705749. [Epub ahead of print]

Tubulin acetylation governs organelle remodeling and lysosomal reformation during neuronal differentiation.

Chih-Hsuan Hsu, Alexander Josiah Kinrade, Maria Clara Zanellati, Sarah Cohen.

A functional nervous system depends on neuronal morphology established during differentiation. The microtubule (MT) cytoskeleton supports neuronal differentiation by organizing organelle positioning and facilitating transport. The dynamics and properties of MTs are regulated by a variety of post-translational modifications (PTMs), with many organelle interactions occurring preferentially on modified MTs. Here we find that tubulin acetylation is enriched at specific subcellular locations during differentiation of human induced neurons. We apply a quantitative multispectral imaging pipeline to simultaneously analyze eight membrane-bound organelles and define how tubulin acetylation reshapes organelle architecture and interaction networks during neuronal differentiation. We find that loss of tubulin acetylation broadly alters organelle morphology, spatial distribution, and inter-organelle interactions, with lysosome-organelle interactions most affected. Loss of acetylated MTs leads to enlarged, highly acidified lysosomes, impaired lysosomal fission, and accumulation of autolysosomes, consistent with defective lysosomal reformation. Super-resolution microscopy further reveals that lysosome-endoplasmic reticulum (ER) contacts preferentially associate with acetylated MTs. Together, our data support a model in which tubulin acetylation coordinates lysosome-ER interactions to facilitate lysosome remodeling and turnover. This work establishes tubulin acetylation as a key cytoskeletal regulator that links organelle interactions to organelle homeostasis important for neuronal differentiation.

DOI: https://doi.org/10.64898/2026.02.13.705749
bioRxiv. 2026 Feb 16. pii: 2026.02.13.705790. [Epub ahead of print]

Neuronal Cell-Cycle Re-entry Defines Divergent Outcomes Through Replication-Dependent DNA Damage in ALS.

Jonathan Plessis-Belair, Roger B Sher.

Cell-cycle dysregulation has emerged as a shared mechanism of neuronal loss across neurodegenerative diseases (NDDs), including amyotrophic lateral sclerosis (ALS), Alzheimer's disease, and Parkinson's disease. In post-mitotic neurons, aberrant reactivation of cell-cycle signaling precedes degeneration, yet the upstream triggers and functional consequences of this process remain poorly defined. Nucleocytoplasmic transport (NCT) dysfunction, a hallmark of ALS and related disorders, disrupts the spatial distribution of key regulatory proteins and may contribute to maladaptive cell-cycle activation. Our recent evidence suggests that impaired nuclear import may initiate, rather than merely accompany, neuronal cell-cycle re-entry. Here, we show that cell-cycle activation in motor neurons distinguishes molecular subtypes and outcomes in ALS. We analyzed the AnswerALS transcriptomic cohort and identified a patient cluster characterized by robust upregulation of cyclins B and D. Clusters with lower levels of cell-cycle gene expression exhibited accelerated ALSFRS-R decline, whereas the highest cyclin-expressing cluster demonstrated comparatively improved functional trajectories over time. To test whether NCT disruption can mechanistically drive aberrant cell-cycle activation, we pharmacologically inhibited importin-β in human iPSC-derived spinal motor neurons. NCT disruption induced widespread proteomic mislocalization, including TDP-43 pathology, and triggered a transient wave of cell-cycle activity preceding neuronal death. Mechanistically, we identified DNA-replication initiation as a pathological event driving degeneration and demonstrated that selective inhibition of G1/S-associated CDK4/6 activity confers neuroprotection. Together, these findings link impaired nuclear import to maladaptive cell-cycle reactivation in neurons and highlight stage-specific engagement of the cell-cycle machinery as a determinant of neuronal vulnerability in ALS.

DOI: https://doi.org/10.64898/2026.02.13.705790
Proc Natl Acad Sci U S A. 2026 Mar 03. 123(9): e2513642123

Neuronal TDP-43 regulates myelin formation via neurexin 1 mRNA stabilization.

Jiayi Li, Yohei Iguchi, Kenji Yoshida, Daisuke Kato, Kunihiko Araki, Kenta Kobayashi, Satoshi Yokoi, Rei Yoshimoto, Madoka Iida, Yoshinobu Amakusa, Yu Kawakami, Takashi Yoshimura, Ryo Chikuchi, Koyo Tsujikawa, Yuichi Riku, Yasushi Iwasaki, Yohei Okada, Nobuhiko Ohno, Hiroaki Wake, Masahisa Katsuno.

  Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) develop as spatial pathologies in which neurons and glial cells are interconnected. TAR DNA-binding protein 43 (TDP-43) is a major pathological protein that is inextricably associated with ALS and FTLD. In this study, we investigated the roles of neuronal TDP-43 in neuron-oligodendrocyte interactions using neuron-specific TDP-43 knockout (TDP-43cKO) mice. TDP-43 depletion in neurons induced hypomyelination, which was confirmed by immunohistochemistry and ultrastructural analysis. In addition, conduction disturbance was revealed by electrophysiological analysis. The hypomyelination of TDP-43cKO mouse was restored by cytoplasmic TDP-43 supplementation in neurons. Neuron-specific transcriptome analysis revealed that neurexin 1 (NRXN1) is the regulatory target of TDP-43, which promotes myelin formation. The hypomyelination of TDP-43cKO mice was also restored by NRXN1b supplementation in neurons. We further confirmed that TDP-43 stabilizes Nrxn1 mRNA by binding to the Nrxn1 3'untranslated region (3'UTR). Although TDP-43cKO exhibited impaired recognition memory, the supplementation of NRXN1 in the hippocampus recovered the memory disturbances. In conclusion, this study demonstrates the neuron-oligodendrocyte interaction mediated by neuronal TDP-43 via NRXN1 mRNA stabilization. These findings shed light on neuron-oligodendrocyte interaction in the disease mechanisms of ALS/FTLD.

Keywords:  TAR DNA-binding protein 43; amyotrophic lateral sclerosis; frontotemporal lobar degeneration; neurexin 1; neurodegeneration

DOI:  https://doi.org/10.1073/pnas.2513642123
bioRxiv. 2026 Feb 13. pii: 2026.02.11.705111. [Epub ahead of print]

Generation and characterization of human iPSC-derived NPC1 I1061T/I10161T i 3 Neurons as a model for NPC1 disease.

Shikha Salhotra, Niamh X Cawley, Christian White, Insung Kang, Anika Prabhu, Cristin D Davidson, Christopher A Wassif, Forbes D Porter.

Niemann-Pick disease, type C is an autosomal recessive, fatal, neurodegenerative disorder caused by pathological variants in NPC1 or NPC2 . Dysfunction of either NPC1 or NPC2 results in impaired intracellular cholesterol transport and subsequent storage of unesterified cholesterol in endolysosomal compartments. Earlier cell-based studies utilized patient fibroblasts to study this disease; however, neuronal cells allow for investigation of the neurodegenerative aspect of NPC1. Expression of neurogenin in induced pluripotent stem cells leads to the generation of i 3 Neurons (integrated, isogenic, and inducible), allowing for rapid, synchronized growth of homogenous neurons. In this study, we report the development and characterization of a human iPSC-derived NPC1 I1061T/I1061T i 3 Neuronal model system. NPC1 I1061T is a missense variant resulting in a misfolded protein targeted for proteasomal degradation in the ER. NPC1 I1061T/I1061T i 3 Neurons phenocopied the cellular pathological features of NPC1 disease including endolysosomal cholesterol accumulation, lysosomal morphological changes, and response to the proteostasis modulator, mo56HC. The NPC1 phenotype was alleviated by 2-hydroxypropyl-β-cyclodextrin treatment, a drug demonstrating efficacy both in vitro and in vivo . This NPC1 I1061T/I1061T i 3 Neuronal cell line can facilitate future high-throughput drug and genomic screens, particularly those aimed at identifying proteostasis regulators that improve the expression/stability of the mutant NPC1 protein.

DOI: https://doi.org/10.64898/2026.02.11.705111
Int J Mol Sci. 2026 Feb 18. pii: 1953. [Epub ahead of print]27(4):

Antisense Dipeptide Repeat Proteins Drive Widescale Purine Metabolism Aberration in C9orf72 Amyotrophic Lateral Sclerosis via ADA.

Benjamin Hall, Lydia Castelli, Adrian Higginbottom, Jingxuan He, Ling-Nan Zou, Heather Walker, Miriam Yagüe-Capilla, Kari E Wong, David J Burrows, Jonathan George, Keaton Hamer, Jenny M Tanner, Ergita Kyrgiou-Balli, Rees Ross, Herbie Garland, Erin Tonkiss, Rachel George, Christopher P Webster, Emma F Smith, Hannah O Timmons, Jess Allsop, Nikolas Stefanidis, Billie D Ward, Ya-Hui Lin, J Robin Highley, Mimoun Azzouz, Ryan J H West, Sean G Rudd, Kurt J De Vos, Pamela J Shaw, Guillaume M Hautbergue, Scott P Allen.

  Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterised by the death of motor neurons leading to paralysis and death, generally 3-5 years post-symptom onset. The most frequent genetic cause of ALS is a hexanucleotide repeat expansion (HRE) in the chromosome 9 open reading frame 72 (C9orf72) gene, that has three major hypothesised pathological mechanisms including the production of dipeptide repeat proteins (DPRs). Our laboratory has previously identified purine metabolism dysfunction in induced neural progenitor cell-derived astrocytes (iAstrocytes) from C9orf72 ALS (C9-ALS) cases (C9-iAstrocytes), driven by loss of the enzyme adenosine deaminase (ADA). Here, we have demonstrated that loss of ADA along with changes to ecto-5'-nucleotidase and hypoxanthine-guanine phosphoribosyl transferase led to disruption in purine metabolite levels including purine dNTP output. These changes were recapitulated in patient CSF, whilst loss of ADA was recapitulated in patient white matter. Immunofluorescence also demonstrated purinosome formation dysfunction in C9-iAstrocytes. These changes are likely driven by DPRs as ADA loss was recapitulated in in vitro and in vivo DPR models. Finally, ADA levels could be recovered by reducing DPR levels either by inhibiting serine/arginine-rich splicing factor 1 or overexpressing RuvB-like 2. Our data demonstrate that DPR production negatively affects purine function in C9-ALS suggesting a potentially pivotal role for purine metabolism dysfunction in C9-ALS pathology.

Keywords:  ADA; ALS; C9orf72; DPR; MND; astrocyte; metabolomics; purine metabolism; purinosome

DOI:  https://doi.org/10.3390/ijms27041953
bioRxiv. 2026 Feb 13. pii: 2026.02.12.705375. [Epub ahead of print]

Discovery of TDP-43 aggregation inhibitors via a hybrid machine learning framework.

Sofia Kapsiani, Sulay Vora, Ana Fernandez-Villegas, Clemens F Kaminski, Nino F Läubli, Gabriele S Kaminski Schierle.

TAR DNA-binding protein 43 (TDP-43) aggregation is a hallmark of several neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal dementia. Recent therapeutic efforts have highlighted the potential of small molecules capable of inhibiting TDP-43 aggregation; however, no effective treatments currently exist. Here, we developed a hybrid machine learning approach combining graph neural network (GNN) embeddings with traditional chemical descriptors and biological target annotations. Using XGBoost as the final classifier enabled model interpretability through SHAP analysis, allowing the identification of key chemical features and target annotations associated with TDP-43 anti-aggregation activity. Complementary Monte Carlo Tree Search analysis highlighted specific chemical substructures linked to predicted activity. By screening an external library of 3,853 small molecules, the model identified two compounds not previously evaluated against TDP-43 aggregation, namely berberrubine and PE859. Molecular docking analysis revealed that both compounds interact favourably with the TDP-43 RNA recognition motif (RRM) domain through distinct binding modes. Experimental validation showed that both compounds significantly reduced TDP-43 aggregation in HEK cells. Further testing in Caenorhabditis elegans expressing human TDP-43 demonstrated that PE859 significantly rescued locomotor defects, while berberrubine showed partial improvement. This work establishes a hybrid machine learning approach for accelerating small molecule drug discovery, yielding two promising therapeutic candidates for TDP-43 proteinopathies.

DOI: https://doi.org/10.64898/2026.02.12.705375
bioRxiv. 2026 Feb 11. pii: 2026.02.09.704902. [Epub ahead of print]

Repeat expansions in C9orf72 rewire the 3D chromatin landscape in ALS.

Tatiana Ulloa Avila, Jingying Wang, Lydia Adams, Ellen Hu, Alvaro A Beltran, Alexey Kozlenkov, Shreyan Urhekar, Ariana B Marquez Gonzalez, Hun-Goo Lee, J Mauro Calabrese, Stella Dracheva, Adriana S Beltran, Won Mah, Hyejung Won.

Amyotrophic lateral sclerosis (ALS) is frequently driven by GGGGCC short tandem repeat (STR) expansions in C9orf72 , yet the mechanisms by which these expansions lead to neurodegeneration remain incompletely understood. Here, we propose a novel mechanism involving higher-order chromatin architecture where C9orf72 -STR expansions induce widespread, neuron-specific gains in chromatin loops that are closely linked to transcriptomic dysregulation in ALS. These ectopic loops colocalize with the genomic binding sites of C9orf72 -STR RNAs and the architectural protein CTCF, supporting a model in which RNA-DNA interactions promote aberrant loop formation. Together, our findings demonstrate how C9orf72 -STR expansions remodel the neuronal genome and disrupt gene expression, uncovering an RNA-driven mechanism of chromatin reorganization in C9-ALS that connects altered nuclear topology to gene dysregulation in neurodegeneration.

DOI: https://doi.org/10.64898/2026.02.09.704902
bioRxiv. 2026 Feb 11. pii: 2026.02.09.704060. [Epub ahead of print]

Intrathecal (G 4 C 2 ) 149 delivery in C9orf72-deficient mice yields mild motor dysfunction and ALS/FTD pathological hallmarks.

Katelyn A Russell, Amelia A Shahrabi, Suleyman C Akerman, Matthew D Byrne, Jeffrey D Rothstein, Davide Trotti, Brigid K Jensen, Aaron R Haeusler.

A repeat expansion in C9orf72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), yet existing mouse models incompletely engage spinal regions implicated in disease. Here, an adeno-associated virus encoding (G 4 C 2 ) 149 repeats was delivered via neonatal intrathecal injection, achieving widespread CNS expression with robust spinal cord targeting. This approach was applied to mice with graded loss of endogenous C9orf72 to interrogate both gain- and loss-of-function mechanisms. Longitudinal motor, behavioral, and pathological analyses revealed that repeat expression primarily drives mild, progressive muscle weakness, whereas coordination deficits were largely genotype dependent. Subtle gait abnormalities and hyperactivity were also observed. Within spinal motor regions, repeat-expressing mice exhibited dipeptide repeat protein accumulation, reduced NeuN-positive area, glial activation, and sparse phosphorylated TDP-43 pathology. Cross-domain correlations further linked repeat expression, spinal pathology, and motor dysfunction. Collectively, these findings establish that CNS-wide repeat expression combined with reduced C9orf72 produces a coherent, mild ALS/FTD model.

DOI: https://doi.org/10.64898/2026.02.09.704060
Cell Rep. 2026 Feb 24. pii: S2211-1247(26)00114-2. [Epub ahead of print]45(3): 117036

Modeling spastic paraplegia 4 with corticospinal motor neuron-enriched cortical organoids reveals genotype-phenotype and HDAC6-targetable pathology.

Neha Mohan, Skandha Ramakrishnan, Xiaohuan Sun, Ying Sun, Theresa Connors, Victor Chai, Emanuela Piermarini, Peter W Baas, James Cai, Mei Liu, Liang Qiang.

  Spastic paraplegia 4 (SPG4), the most common form of hereditary spastic paraplegia, causes progressive gait deficiency due to corticospinal tract degeneration. SPG4 results from mutations in the SPAST gene, which encodes spastin, a microtubule-severing AAA-ATPase. To dissect genotype-phenotype relationships, we generated isogenic human induced pluripotent stem cell lines carrying either an SPAST missense (SPASTWT/C448Y) or truncation (SPASTWT/S245X) mutation and differentiated them into corticospinal motor neuron-enriched cortical organoids. These models revealed mutation-specific patterns of aberrant neuronal activity, microtubule hypoacetylation, and axonal degeneration. We identified mutant M1-spastin-induced hyperactivation of histone deacetylase 6 (HDAC6), a major tubulin deacetylase, as the key pathogenic culprit. Pharmacological inhibition of HDAC6 with tubastatin A restored microtubule acetylation and rescued axonal degeneration in organoids, with corresponding improvements in corticospinal tract integrity and gait defects in SPG4 transgenic mice. Our study uncovers HDAC6 hyperactivation as a targetable mechanism for SPG4 and verifies human organoids as a platform for therapeutic discovery.

Keywords:  CP: neuroscience; CP: stem cell research; SPAST; cortical organoids; corticospinal motor neurons; histone deacetylase 6; human induced pluripotent stem cells; microtubule acetylation; spastic paraplegia 4; spastin; tubastatin A

DOI:  https://doi.org/10.1016/j.celrep.2026.117036
medRxiv. 2026 Feb 09. pii: 2026.02.06.26345684. [Epub ahead of print]

Wild-type C9orf72 expression is a genetic modifier of C9-ALS survival.

Answer ALS Consortium

1 Amyotrophic lateral sclerosis (ALS) is highly heritable, yet the vast majority of cases lack an identifiable genetic cause and clinical progression remains largely unpredictable. To connect noncoding and rare genetic variation to disease phenotypes in a relevant cell type, we generated a multi-omic quantitative trait locus (QTL) atlas from 594 induced-pluripotent-stem-cell-derived human motor neuron lines (522 ALS patients, 72 controls). By mapping cis-QTLs for chromatin accessibility, splicing and gene expression from whole-genome sequencing, we identify common and rare variants on the wild-type C9orf72 allele that form regulatory haplotypes. These haplotypes influence C9orf72 expression levels in motor neurons and stratify C9-ALS patients into four subgroups; using clinical disease duration data and longitudinal ALSFRS-R scores, we show that these subgroups exhibit different survival trajectories, indicating that wild-type C9orf72 expression acts as a genetic modifier of disease duration. Beyond the C9orf72 locus, we detect ultra-rare intronic variants that create cryptic exons and structural and nonsense variants in established ALS genes, providing likely genetic explanations for disease in additional patients who previously lacked a molecular diagnosis. Our results show that QTL mapping in patient-derived motor neurons can reveal regulatory modifiers of progression and hidden pathogenic events in ALS, providing a framework for genetically informed risk attribution and patient stratification in complex neurological diseases.

DOI: https://doi.org/10.64898/2026.02.06.26345684
Innovation (Camb). 2026 Jan 05. 7(1): 100989

Next questions of autophagy in neurodegenerative diseases: From mechanisms to therapeutics.

Rongcan Luo.

Autophagy, a key cellular degradation pathway, is central to the pathogenesis of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Despite progress in understanding its role, critical questions remain. This perspective highlights pressing issues, including cell-type-specific autophagy regulation, interactions with other cellular pathways, and challenges in translating autophagy-modulating therapies to clinical practice. Addressing these questions will advance our understanding of neurodegenerative diseases and pave the way for novel therapeutics.

DOI: https://doi.org/10.1016/j.xinn.2025.100989
Protein Sci. 2026 Mar;35(3): e70506

The endoplasmic reticulum in mitochondrial protein targeting: A neuronal perspective on organelle crosstalk.

J Tabitha Hees, Angelika B Harbauer.

  Neurons depend on tightly regulated spatial proteostasis to maintain function across their extended morphology. The endoplasmic reticulum (ER), traditionally known for its function in protein synthesis, folding, and trafficking, has long been recognized as a central platform for directing proteins to organelles of the secretory and endocytic pathways. In contrast, its involvement in the targeting of mitochondrial proteins, which are not directly connected to classical trafficking routes, remains less well understood and has only recently gained attention. Growing evidence implicates the ER in post-translational delivery of mitochondrial precursors through mechanisms that integrate local translation, chaperone activity, and dynamic organelle contact sites. ER-mitochondria contacts form dynamic platforms for precursor translation, stabilization and transfer, as exemplified by pathways such as ER-SURF. Endolysosomes add an additional layer of regulation by influencing both ER function and mitochondrial proteostasis. However, how these processes are mechanistically coordinated, particularly in neurons with their complex architecture, remains incompletely understood. In this review, we synthesize the current understanding on ER-mediated mitochondrial protein targeting, highlight the role of membrane contact sites between ER, mitochondria and endolysosomes, and discuss how chaperone networks and signaling pathways shape mitochondrial precursor handling. We further explore how disruption of these systems might contribute to neurodegeneration, positioning organelle crosstalk as a critical determinant of mitochondrial proteostasis and neuronal health.

Keywords:  ER‐SURF; endoplasmic reticulum; mitochondrial protein targeting; neurodegeneration; organelle crosstalk

DOI:  https://doi.org/10.1002/pro.70506
Biol Cell. 2026 Feb;118(2): e70051

A Robust Methodological Framework for Generating Whole-Brain and Cortical Organoids From Diverse Healthy- and Patient-Derived Induced Pluripotent Stem Cell Lines.

Tara Fournier, Eugenia Pugliese, Benjamin Montagne, Chiara Cimmaruta, Miria Ricchetti.

   BACKGROUND: Patient-derived neural organoids (NOs) have emerged as powerful tools for modeling human neurodevelopmental disorders, especially when animal models are unavailable or fail to recapitulate human-specific cortical development. However, significant variability in differentiation potential, even among healthy donor lines, and especially in fragile patient-derived induced pluripotent stem cells (iPSCs), poses major methodological challenges. Protocols that succeed in one line may fail in others, leading to poor organoid formation, reduced growth, impaired neuroepithelial patterning, or complete failure to generate neural tissues.
METHODS: By systematically comparing multiple published protocols, we identified key sources of variability and ultimately developed optimized protocols for generating both whole-brain (WB) and cortical organoids (CO) from human iPSCs (hiPSCs), including lines from progeroid Cockayne syndrome patients.
RESULTS: Through iterative refinement of critical parameters, including cell seeding density, Matrigel incorporation, and timing and type of pathway inhibition, we achieved consistent organoid growth and structural organization across all tested lines. The resulting pipeline is adaptable and can be further tailored for newly derived or particularly challenging hiPSC lines.
CONCLUSION: Collectively, this methodological framework enables robust and reproducible generation of NOs from genetically diverse hiPSC sources, providing a reliable platform for studying human neurodevelopment and disease mechanisms in progeroid and other patient-specific contexts.

Keywords:  TRIPLE‐I; cortical organoids; hiPSCs; patterning protocols; progeroid disease; whole‐brain organoids

DOI:  https://doi.org/10.1111/boc.70051
Sci Signal. 2026 Feb 24. 19(926): eadx8680

Temporal proteomic and phosphoproteomic dynamics during neuronal differentiation in the reference iPSC line KOLF2.1J.

Ying Hao, Ziyi Li, Erika Lara, Daniel M Ramos, Marianita Santiana, Benjamin Jin, Jacob Epstein, Isabelle Kowal, Jasmin Camacho, Nicole Carmiol, Jae-Hyeon Park, Aleksandra Beylina, Linda G Yang, Jessica T Root, Dylan C Sacks, Paige Jarreau, Cory A Weller, Sydney Klaisner, Laurel A Screven, Caroline B Pantazis, Mike A Nalls, Priyanka Narayan, Luigi Ferrucci, Andrew B Singleton, Michael E Ward, Mark R Cookson, Yue Andy Qi.

Induced pluripotent stem cell (iPSC)-derived neurons are a powerful tool with which to investigate both neuronal development and neurodegenerative diseases. Here, we applied quantitative proteomic and phosphoproteomic analyses to profile the neuronal differentiation of the KOLF2.1J iPSC line, the first reference line of the iPSC Neurodegenerative Disease Initiative (iNDI) project. We developed an automated workflow enabling high-coverage enrichment of proteins and phosphorylated peptides, which revealed molecular signatures during the differentiation of iPSC-derived neurons. Proteomic data highlighted distinct changes in mitochondrial pathways throughout the course of differentiation, whereas phosphoproteomic data revealed specific regulatory dynamics in GTPase-mediated signaling pathways and microtubule proteins. Additionally, phosphosite dynamics were not correlated to changes in protein abundance, particularly in processes related to axon functions and RNA transport. We measured the dynamic changes in kinases that are critical for neuronal development and maturation and developed an interactive web app to visualize the temporal landscape dynamics of protein and phosphosite abundance. By establishing baselines of proteomic and phosphoproteomic profiles for neuronal differentiation, this dataset is a valuable resource for future research into neuronal development and neurodegenerative diseases using this reference iPSC line.

DOI: https://doi.org/10.1126/scisignal.adx8680
EMBO Mol Med. 2026 Feb 23.

Encephalopathy-linked UFM1 variants impede neuronal protein translation, development, and function.

Catarina Perdigão, Josefa Torres, Helge M Magnussen, Janina Koch, Elena Rudashevskaya, Frederieke Moschref, Maksims Fiosins, Fritz Benseler, Sally Wenger, Tanja Nilsson, Sabine Beuermann, Stefan Bonn, Silvio O Rizzoli, Yogesh Kulathu, Olaf Jahn, Benjamin H Cooper, Mateusz C Ambrozkiewicz, JeongSeop Rhee, Nils Brose, Marilyn Tirard.

  Genetic variants that hinder post-translational protein modifications by UFM1, UFMylation, cause encephalopathies. UFMylation regulates endoplasmic reticulum (ER) homeostasis, but how UFMylation deficiencies cause selective neurological defects is unknown. Using murine UFM1-deficient neurons, we investigated two types of UFMylation pathologies, UFM1 loss and expression of a pathogenic UFM1-R81C variant. We found that UFM1-deficiency confounds neuron development and synapse function. Mechanistically, UFM1 loss is associated with induction of ER stress, activation of the unfolded protein response (UPR) pathway, and reduced protein translation. These defects are rescued by wild-type UFM1, but only partially by UFM1-R81C. UFM1-deficient and UFM1-R81C-expressing neurons display distinct responses to ER stress, indicating that UFM1-R81C is not merely a loss-of-function variant. Exploring therapeutic options, we show that Trazodone, an inhibitor of the UPR, restores protein translation solely in UFM1-R81C-expressing neurons, and increases synapse numbers in both UFM1-KO and UFM1-R81C-expressing neurons. Our study unveils a pivotal role for UFMylation in neuronal development, provides a molecular understanding of the signaling mechanisms altered in UFM1-associated encephalopathies, and offers important insights into potential treatments for these disorders.

Keywords:  Encephalopathies; Neuron; Synapse; UFM1; Unfolded Protein Response

DOI:  https://doi.org/10.1038/s44321-026-00389-6
J Vis Exp. 2026 Feb 06.

Isolation and Quantification of Axonal mRNAs Using Porous Membrane Inserts and RTddPCR.

Shruti Ghumra, Manasi Agrawal, Meghal Desai, Lahiri Kuchibatla, Pabitra K Sahoo.

The spatial dynamics of mRNA localization and translation within neurons are essential for various mechanisms of neuronal function, including neuronal connectivity, synaptic plasticity, and response to injury. Due to the extreme polarity of neurons, many of these functions rely on the ability of axons to locally translate specific transcripts. However, quantifying these subcellular RNA populations remains technically challenging. Here, we describe a reproducible approach for obtaining separate somatic and axonally enriched compartments from cultured rodent neurons and for quantifying compartment-specific mRNA expression. Primary rodent embryonic or adult neurons were cultured on inserts with a porous membrane of size 1-3 µm. These membranes are only permissive to axons, allowing physical separation of the somatic and axonal compartments. RNA was then isolated from the whole neuron and axon-enriched fractions separately, which were further used for reverse transcriptase droplet digital PCR (RTddPCR) with gene-specific primers. This system offers an absolute quantitative comparison between subcellular compartments, enabling high-sensitivity detection of localized transcripts. This approach measures steady-state RNA abundance and facilitates examination of axonal RNA changes over time in response to neurotrophic factors, stress, or injury models. The combination of physical compartmentalization and RTddPCR analysis reduces cross-contamination and gives exact copy numbers of rare transcripts, offering high sensitivity, reproducibility, and detection of low-copy-number mRNAs that control axon growth and regeneration. This method also works with downstream tests, such as measuring protein synthesis, studying RNA stability, and doing perturbation experiments using siRNA or drugs that block certain proteins. Importantly, this technique can be adapted for different neuronal subtypes, developmental stages, or injury models. In general, this approach is a flexible, sensitive, and reproducible way to study the molecular basis of axonal mRNA localization and how it affects neuronal function and disease mechanisms.

DOI: https://doi.org/10.3791/69601
Res Sq. 2026 Feb 19. pii: rs.3.rs-8380062. [Epub ahead of print]

Reversing Mitochondrial Dysfunction in Optineurin E50K Glaucoma: A Metabolic Approach to Neuroprotection.

Bledi Petriti, Shobana Subramanian, Pete Williams, Kai-Yin Chau, Pawel Licznerski, Gerassimos Lascaratos, Soledad Aguilar-Munoa, Deborah Kamal, Haesoo Bae, Kambiz Alavian, David Garway-Heath, Elizabeth Jonas.

Mutations in optineurin (OPTN) are linked to neurodegenerative diseases such as normal tension glaucoma (NTG) and amyotrophic lateral sclerosis. The E50K-OPTN mutation is the most common genetic cause of NTG, where it disrupts mitophagy and leads to the accumulation of dysfunctional mitochondria. To understand how cellular metabolism is altered in these persistent mitochondria, and whether any pathological state can be reversed, we investigated NTG-patient-derived fibroblasts carrying the E50K-OPTN mutation. We identified a form of mitochondrial leak metabolism driven by elevated levels of the ATP synthase c-subunit leak channel (ACLC). These cells exhibit reversed F1FO ATP synthase activity, increased mitochondrial proton leak, and fragmented mitochondria, resulting in inefficient oxidative phosphorylation and a shift toward aerobic glycolysis and high protein synthesis rate. The ratio of ATP synthase c-subunit to β-subunit was markedly elevated, suggesting open ACLC pores. Treatment with dexpramipexole normalized ATP synthase function and cellular metabolism, promoted ATP synthesis rather than hydrolysis and reduced protein synthesis rates. Dexpramipexole reduced p62 levels in E50K fibroblasts, consistent with a reduced mitophagic burden from decreased accumulation of damaged mitochondrial cargo. These findings identify ACLC-mediated leak as a central driver of metabolic dysfunction in E50K-OPTN glaucoma and suggest ACLC closure as a viable therapeutic strategy.

DOI: https://doi.org/10.21203/rs.3.rs-8380062/v1
bioRxiv. 2026 Feb 13. pii: 2026.02.11.705390. [Epub ahead of print]

TRIM32-UBQLN2-p62 axis promotes TDP-43 inclusion formation and amyloid aggregation through shuttle condensates.

Ziyan He, Jiechao Zhou, Rongzhen Zhang, Fei Meng, David W Nauen, Juan C Troncoso, Paul F Worley, Wenchi Zhang.

Aberrant protein aggregation is a hallmark of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD), which share overlapping genetic and pathological features. Similar aggregates are increasingly recognized in Alzheimer's disease (AD) and limbic-predominant age-related TDP-43 encephalopathy (LATE). However, it remains unclear whether a shared molecular pathway drives this pathological aggregation. Here, we report that the E3 ubiquitin ligase TRIM32, together with the shuttle factor UBQLN2 and the autophagy adaptor p62/SQSTM1, form condensates that depend on E3 ligase activity and a network of intermolecular interactions. These condensates act as scaffolds that capture UBQLN2 client proteins, including TDP-43 and ANXA11, and modulate their mobility. A unique hydrophobic loop within TRIM32's substrate-binding domain mimics low-complexity motifs in ANXA11 and TDP-43, enabling selective retention via competitive binding mediated by UBQLN2 STI1 domain. Moreover, TRIM32 condensates promote amyloid aggregation of TDP-43, an effect that is exacerbated by pathogenic UBQLN2 mutation. In brains from individuals with diverse neurodegenerative diseases, TRIM32 co-localizes with pathological phospho-TDP-43 (pTDP-43) inclusions, supporting a model in which TRIM32-driven condensates function as selective proteostasis sorting compartments that broadly contribute to TDP-43 proteinopathy.

DOI: https://doi.org/10.64898/2026.02.11.705390
Mol Biol Cell. 2026 Feb 25. mbcE24030109

Autophagosome turnover requires Arp2/3 complex-mediated maintenance of lysosomal integrity.

Corey J Theodore, Lianna H Wagner, Kenneth G Campellone.

Autophagy is an intracellular degradation process that maintains homeostasis, responds to stress, and plays key roles in preventing aging and disease. Autophagosome biogenesis, vesicle rocketing, and autolysosome tubulation are controlled by multiple actin cytoskeletal factors, but the impact of actin assembly on completion of the autophagic degradation pathway is not well understood. Here we studied autophagosomes and lysosomes in mouse fibroblasts harboring an inducible knockout (iKO) of the Arp2/3 complex, an essential actin nucleator. Arp2/3 complex ablation resulted in increased basal levels of autophagy receptors and lipidated membrane proteins from the LC3 and GABARAP families. Such phenotypes were accompanied by the steady-state presence of abnormally high numbers of autolysosomes and an inability of the Arp2/3 complex-deficient cells to complete autolysosome turnover due to lysosomal damage. When normal cells were treated with a lysosomal membrane-disrupting agent, the Arp2/3-activating protein WHAMM was recruited to lysosomes, and Arp2/3 complex activity was required for restoring intact lysosomal structure. Deletion of WHAMM in mouse or human fibroblasts decreased Arp2/3 localization to lysosomes and increased lysosomal damage. These results reveal the importance of the Arp2/3 complex and WHAMM for autophagic degradation and uncover a new role for the actin nucleation machinery in maintaining lysosomal integrity.

DOI: https://doi.org/10.1091/mbc.E24-03-0109
J Integr Neurosci. 2026 Feb 26. 25(2): 44709

Advances and Challenges in the Use of Spinal Cord Organoids in ALS.

Yongxiang Zhang, Binghong Chen, Yuanxiang Lin, Dezhi Kang, Tong Zhao.

  Amyotrophic lateral sclerosis (ALS) is a complex neurodegenerative disease. No effective treatments have yet been found for ALS, primarily because the molecular mechanisms that underlie its pathogenesis are unknown. Although animal models are suitable for ALS research, species differences between these models and human spinal cord organs make it difficult to accurately predict the progression of disease in humans. Therefore, the development of more suitable models is urgently needed. Human stem cells have unlimited development potential and can be used to make three-dimensional organoid structures that mimic the architecture and function of actual organs. Organoid models can be used to overcome some of the species differences and accelerate experimental research, leading to the development of practical applications for the treatment of ALS. This article discusses the pathological mechanisms and cell types involved in ALS, as well as the genes associated with this disease. We also discuss the possible applications of spinal cord organoids (SCOs) in ALS research, such as the modeling of disease characteristics, study of pathological mechanisms, and drug screening. Finally, the prospects for SCOs in ALS treatment are highlighted, while acknowledging the need for further development of relevant technologies.

Keywords:  amyotrophic lateral sclerosis; application; organoids; prospect; review; spinal cord

DOI:  https://doi.org/10.31083/JIN44709
J Cell Biol. 2026 Apr 06. pii: e202501146. [Epub ahead of print]225(4):

Cdc5-mediated Ulp2 phosphorylation controls the timing of polySUMOylation during the cell cycle.

Emily Gutierrez-Morton, Raed Rizkallah, Tomiwa Lawal, Marie-Helene Kabbaj, Sophia L Owutey, Robert J Tomko, Yanchang Wang.

SUMOylation is a posttranslational modification, and polySUMOylation can further trigger protein ubiquitination and relocalization to facilitate cell cycle progression. Previous studies show cell cycle-dependent polySUMOylation in budding yeast, and depletion of SUMO protease Ulp2 causes premature polySUMOylation. Furthermore, Ulp2 undergoes phosphorylation in a manner dependent on mitotic kinase Cdc5. In this study, we report that Cdc5 is necessary for protein polySUMOylation and artificially tethering Cdc5 to Ulp2 is sufficient to trigger polySUMOylation. We further identified serine 734 as the primary phosphorylation site on Ulp2, which is regulated by Cdc5 kinase and Rts1-associated PP2A phosphatase. Notably, phosphodeficient ulp2S734A mutant suppressed the polySUMOylation induced by CDC5 overexpression or RTS1 deletion. Finally, we found that Ulp2 phosphorylation at serine 734 compromised its binding to SUMO chains. Collectively, these results demonstrate that Cdc5-dependent phosphorylation of SUMO protease Ulp2 reduces its SUMO chain affinity and induces protein polySUMOylation, but PP2ARts1 counteracts this to prevent premature polySUMOylation.

DOI: https://doi.org/10.1083/jcb.202501146
Brain Pathol. 2026 Feb 24. e70088

The DNA/RNA autophagy protein SIDT2 as a novel neuropathological hallmark in Huntington disease.

Sanaz Gabery, Sofia Bergh, Chrisovalantou Huridou, Rachel Y Cheong, Barbara Baldo, Paul Günther Scheunemann, Marie-Louisa Schoebel, Linda Holmquist Mengelbier, Elisabet Englund, Catriona McLean, Carsten Saft, Deniz Kirik, Maria Björkqvist, Glenda Halliday, Elisabeth Petrasch-Parwez, Huu Phuc Nguyen, Jonasz Jeremiasz Weber, Åsa Petersén.

  The pathogenic mechanisms leading to neurodegeneration in Huntington disease (HD) are not fully understood but involve accumulation of toxic mRNA and protein products in the brain. Recent studies described an unconventional autophagic pathway involving DNA and RNA degradation through DNautophagy and RNautophagy that is regulated by the lysosomal protein SID1 transmembrane family member 2 (SIDT2). Interestingly, SIDT2 has been shown to bind to the expanded CAG repeat in the mutant huntingtin (mHTT) transcript and lower mHTT in vitro. The aim of the present study was to determine whether SIDT2 levels are altered in HD and whether manipulation of SIDT2-mediated RNautophagy can alter HD pathology. We demonstrate a significant reduction of SIDT2 protein levels in the striatum and in the lateral hypothalamic area in postmortem HD brains compared to control cases without effects on SIDT2 mRNA levels. In frontal cortical postmortem HD tissue, we show a CAG-repeat-length-dependent increase in the frequency of SIDT2-immunoreactive intranuclear inclusions. In postmortem tissue of an HD case with Vonsattel grade 0, we demonstrate SIDT2- and mHTT-immunoreactive inclusions not only in the frontal cortex, but also in the striatum and the lateral hypothalamic area. In the R6/2 mouse model of HD, we show that SIDT2 inclusions form at later stages than mHTT inclusions. Overexpression of SIDT2 using adeno-associated viral vectors injected into the hypothalamus of R6/2 mice led to a reduction of mHTT inclusions in the lateral hypothalamic area. Similarly, in a neuronal cell model, overexpression of SIDT2 reduced soluble and insoluble mHTT exon 1 protein levels. Taken together, our results reveal novel pathology in clinical HD cases and in experimental models, characterized by the accumulation of SIDT2-immunoreactive inclusions, while demonstrating the efficacy of overexpressing SIDT2 for lowering detrimental mHTT species. Targeting SIDT2-mediated RNautophagy may offer a potential strategy to ameliorate the molecular pathology in HD.

Keywords:  SIDT2; aggregation; huntingtin; huntingtin lowering; inclusions; neuropathology

DOI:  https://doi.org/10.1111/bpa.70088
bioRxiv. 2026 Feb 09. pii: 2025.12.26.696633. [Epub ahead of print]

Stemness factor Mex3a times translation and protein trafficking to ensure robust differentiation of olfactory sensory neurons.

Martín Escamilla Del Arenal, Lauren C Tang, Albana Kodra, Hani Shayya, Aileen Ugurbil, Olga Stathi, Keskin Abdurrahman, Adan Horta, Joan Pulupa, Junqiang Ye, Marko Jovanovic, Stavros Lomvardas, Rachel Duffié.

During the switch from progenitor to differentiated cell, cellular physiology must change to accommodate increased translation and trafficking of membrane-bound proteins. We identify RNA-binding and E3 ubiquitin ligase Mex3a as a key driver of proper neuronal differentiation by regulating mRNA translation and trafficking of cell surface proteins in the context of Unfolded Protein Response (UPR) signaling. Loss of Mex3a in immature olfactory sensory neurons (OSNs) leads to defects in cilia structure, cell surface protein expression, and planar cell polarity in mature OSNs. Proteomics reveal a Mex3a-dependent decrease in proteins related to vesicle transport, lipid metabolism, and ribosome biogenesis. We identify RNA and ubiquitin targets of Mex3a and provide evidence that Mex3a may confer K27 ubiquitin linkage on substrates. Finally, modulating cellular levels of Mex3a changes the recruitment of translation factors Serbp1 and p-eEF2 to ribosomes with possible effects on translation. Our data reveal how a stemness factor regulates development post-transcriptionally and post-translationally to ensure robust differentiation.
Highlights: Loss of stemness factor Mex3a in immature olfactory neurons leads to defects in mature olfactory neurons.Translation/Trafficking of cell surface proteins, cilia structure, and planar cell polarity are compromised in the absence of Mex3a.Mex3a may confer K27 ubiquitination on stress granule protein Serbp1 and ribosome protein Rps7.Mex3a levels are associated with Serbp1 and p-eEF2 recruitment to ribosomes.

DOI: https://doi.org/10.64898/2025.12.26.696633
JCI Insight. 2026 Feb 23. pii: e181013. [Epub ahead of print]11(4):

Ubiquitin ligase Nedd4 regulates the abundance and toxicity of mutant huntingtin.

Hyunkyung Jeong, Yiyang Qin, Fangke Xu, Katarina Trajkovic, Myung Jong Kim, Nicolas Marotta, Kana Hamada, Ravi Allada, Su Yang, Dimitri Krainc.

  Huntington's disease (HD) is a neurodegenerative disorder caused by the expansion of CAG repeats in the gene encoding huntingtin. Since accumulation of mutant huntingtin (mHtt) leads to dysfunction of numerous cellular pathways and toxicity, reducing levels of the mutant protein represents a key therapeutic objective in HD. We found that ubiquitination of mHtt by E3 ubiquitin ligase Nedd4 promotes clearance of the mutant protein. Knockdown of Nedd4 increased toxicity of mHtt in mouse primary neurons and in a fly model of HD, suggesting the protective role of Nedd4. Importantly, levels of Nedd4 were decreased in mHtt-expressing neurons through impaired mTORC1 activity, suggesting a feedback loop of mHtt accumulation and Nedd4 reduction that leads to accumulation and, ultimately, toxicity of mHtt. These findings suggest that restoring Nedd4 activity may offer a novel therapeutic opportunity for HD.

Keywords:  Cell biology; Neurodegeneration; Neuroscience

DOI:  https://doi.org/10.1172/jci.insight.181013
bioRxiv. 2026 Feb 11. pii: 2026.02.10.704675. [Epub ahead of print]

Organelle communication networks rewire to support lipid metabolism during neuronal differentiation.

Maria Clara Zanellati, Zachary Coman, Disha Bhowmik, Chih-Hsuan Hsu, Richa Basundra, Shannon N Rhoads, Ngudiankama R Mfulama, Brandie M Ehrmann, Mohanish Deshmukh, Sarah Cohen.

Cell fate transitions require coordinated remodeling of intracellular organelles, but how the organelle interactome rewires during neurogenesis remains unclear. Here we combine multispectral imaging with quantitative organelle signature analysis to simultaneously map eight organelles at single-cell resolution as human induced pluripotent stem cells (iPSCs) differentiate into forebrain-like neurons. We find compartment and time-specific rescaling of organelles and a progressive increase in higher-order membrane contacts, with mitochondria emerging as an early interaction hub. Later, endoplasmic reticulum (ER)-organelle contacts dominate with ER-peroxisome contacts promoting plasmalogen biosynthesis, membrane homeostasis and synapse formation. Disrupting this contact impairs plasmalogen production, synaptic organization, and neuronal activity, identifying the ER-peroxisome axis as a key regulator of neuronal maturation.

DOI: https://doi.org/10.64898/2026.02.10.704675
Cells. 2026 Feb 09. pii: 322. [Epub ahead of print]15(4):

The Calcium Connection: Explaining Motor Neuron Vulnerability in ALS.

Tristan Dellazizzo Toth, Silvano Bond, Smita Saxena.

  ALS is a severe neuromuscular disease classically characterized by the progressive loss of motor neurons, leading to incremental muscle weakness and eventually death. Current treatment options for ALS have proven to have limited effect, merely delaying the progression of symptoms and prolonging patient survival. This motor neuron subtype-related differential vulnerability has been linked to neuron excitability, metabolism, and protein aggregation. Calcium dysregulation, which serves as an important second messenger in neural signaling pathways, has been implicated in each of these mechanisms and represents a potential target for therapeutic intervention. Armed with cutting-edge tools for visualizing and recording calcium transients in vivo, ALS researchers have delved deeper into the role of calcium dysregulation in disease in recent years. Vulnerable motor neuron populations display an excess of calcium-permeable ion channels together with reduced expression of calcium-binding proteins, generating a cellular environment primed for excitotoxic stress. Loss of inhibitory synaptic input further heightens susceptibility to calcium overload. Paradoxically, some evidence suggests that elevated neuronal activity can exert neuroprotective effects, highlighting the complexity of activity-dependent calcium signaling in ALS. Additionally, ALS-related toxic protein accumulation disrupts calcium homeostasis, contributing to endoplasmic reticulum stress and mitochondrial dysfunction. Emerging data indicate that calcium dysregulation impairs neuron-glia communication, amplifying neuroinflammation and accelerating disease progression. This review aims to synthesize current evidence on how calcium imbalance contributes to motor neuron vulnerability and degeneration in ALS. By exploring the cellular, synaptic, and network-level mechanisms of calcium dysregulation in ALS, the review examines its interplay with mitochondrial and ER stress and explores its impact on neuron-glia interactions with the aim of synthesizing key mechanistic insights into the disease pathogenesis and therapeutic targets.

Keywords:  ALS; calcium; motor neuron; neurodegeneration; selective vulnerability

DOI:  https://doi.org/10.3390/cells15040322
Front Cell Neurosci. 2026 ;20 1731669

C9orf72-ALS mutation drives basal mitophagy impairments in iNeurons.

James A K Lee, Chloe Moutin, Sarah Granger, Katie Roome, Allan Shaw, Scott P Allen, Laura Ferraiuolo, Pamela J Shaw, Heather Mortiboys.

   Introduction: ALS is a neurodegenerative disorder characterized by progressive upper and lower motor neuron loss. A GGGGCC hexanucleotide repeat expansion (HRE) in the C9orf72 gene is the most common mutation found in populations of European descent. Mitochondrial dysfunction has been observed in C9orf72-ALS patients and models of the disease, however, reports on mitochondrial clearance via mitophagy in C9orf72-ALS are limited.
Results: iNeurons from C9orf72-ALS patients displayed reduced mitochondrial membrane potential and reduced basal mitophagy, due to reductions in autophagosome production and reduced ULK1 recruitment to mitochondria. No consistent changes to PINK1/Parkin or BNIP3 mitophagy pathways were observed.
Conclusion: Our data show that certain aspects of mitochondrial function is impaired in C9orf72-ALS patient iNeurons. An in-depth characterization of mitophagy suggests that a deficit in autophagosome production is responsible and provides further evidence that toxic gain-of-function mechanisms in C9orf72-ALS are responsible for autophagy deficits.

Keywords:  ALS (Amyotrophic lateral sclerosis); ULK1; autophagy; mitochondria; mitophagy

DOI:  https://doi.org/10.3389/fncel.2026.1731669
Biochem Pharmacol. 2026 Feb 20. pii: S0006-2952(26)00162-0. [Epub ahead of print]248 117831

Role of nuclear import proteins in maintaining proteostasis and disease pathogenesis.

Xiuling Zhao, Liping Pu, Xuhui Zeng, Junyu Nie.

  Nuclear import receptors (NIRs), particularly the importin α/β heterodimer system, function as essential gatekeepers of nucleocytoplasmic trafficking by decoding diverse nuclear localization signals (NLSs) to orchestrate cellular proteostasis. This review delineates the structural basis of NLS recognition and the coordinated mechanisms that facilitate the nuclear import of critical cargoes, including transcription factors, RNA-binding proteins, and DNA repair factors. Beyond their canonical transport role, we emphasize the emerging functions of NIRs as molecular chaperones that suppress aberrant phase separation and their co-translational regulatory roles in ensuring proper protein biogenesis and folding. The collapse of these regulatory functions underpins the pathogenesis of major human diseases. We examine in detail the pathological consequences of nuclear import dysfunction, highlighting its central role in specific neurodegenerative disorders such as Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD), oncogenic transformation, and viral pathogenesis. The discussion provides a critical appraisal of emerging therapeutic strategies that target the nuclear import machinery, including small-molecule inhibitors (e.g., importazole, ivermectin), peptide competitors, and advanced delivery platforms. We conclude by providing the associated challenges such as achieving tissue specificity, avoiding off-target effects and the significant opportunities that lie in pharmacologically modulating this fundamental pathway to restore proteostasis and develop disease modifying therapies.

Keywords:  Importin α/β; NLS; Nuclear import; Pathogenesis; Proteostasis

DOI:  https://doi.org/10.1016/j.bcp.2026.117831
Cell Prolif. 2026 Feb 26. e70189

Clinical-Grade Human Induced Pluripotent Stem Cell-Derived Neural Precursor Cells Restore Motor Function and Preserve Striatal Integrity in a Quinolinic Acid-Lesioned Rat Model of Huntington's Disease.

Hyeonjoong Jeon, Il-Shin Lee, Sanghun Lee, Hyo Chang Park, Beomsoo Kim, Hyun Sook Kim, Jihwan Song.

  Huntington's disease (HD) is an inherited neurodegenerative disease characterised by progressive degeneration of GABAergic medium spiny neurons (MSNs) in the striatum. Neural precursor cells (NPCs) derived from human induced pluripotent stem cells (iPSCs) have been considered as a promising and scalable source for neuronal replacement and circuit restoration. In this study, we investigated the therapeutic effects of a clinical-grade, human leukocyte antigen (HLA)-homozygous iPSC line (YZWJ-s513) differentiated into NPCs (s513-NPCs) in a quinolinic acid (QA)-lesioned rat model of HD. Following intrastriatal transplantation, s513-NPCs not only survived for 12 weeks but also differentiated into neurons, astrocytes, and oligodendrocytes, while generating new DARPP32+ GABAergic MSNs. Specifically, graft-derived neurons projected to the host globus pallidus, indicating structural integration into the striato-pallidal pathways. Additionally, NPC-transplanted rats exhibited significant motor recovery across multiple tasks for up to 12 weeks, accompanied by reduced striatal atrophy and ventricular enlargement. Histological findings also revealed attenuated astrogliosis and microgliosis, along with a shift toward an anti-inflammatory milieu. Collectively, these results demonstrate that transplantation of clinical-grade, HLA-homozygous iPSC-derived NPCs can provide both neuronal replacement and modulation of the diseased microenvironment, supporting their potential as a regenerative therapy for HD. Key quality attributes and release criteria supporting the clinical-grade characterisation of the cell product used in vivo are summarised in Table S1.

Keywords:  HLA‐homozygous; Huntington's disease; induced pluripotent stem cells; medium spiny neurons; neural precursor cells; neuroinflammation; quinolinic acid (QA)

DOI:  https://doi.org/10.1111/cpr.70189
Cells. 2026 Feb 13. pii: 342. [Epub ahead of print]15(4):

Membrane Dysfunction as a Central Mechanism in LRRK2-Associated Parkinson's Disease: Comparative Analysis of G2019S and I1371V Variants.

Khushboo Singh, Roon Banerjee, Chandrakanta Potdar, Anisha Shaw, Rakshith Rakshith, Nitish Kamble, Vikram Holla, Ravi Yadav, Pramod Kumar Pal, Indrani Datta.

  Mutations in leucine-rich repeat kinase 2 (LRRK2) are among the most common genetic causes of Parkinson's disease (PD), yet substantial heterogeneity exists among pathogenic variants. How mutations in distinct functional domains of LRRK2 differentially perturb cellular homeostasis remains incompletely understood. Here, we compared two pathogenic LRRK2 mutations-G2019S in the kinase domain and I1371V in the GTPase domain-across multiple cellular models, including SH-SY5Y and U87 cells, and healthy human iPSC-derived floor plate cells. We demonstrate that the I1371V mutation induces markedly more severe cellular dysfunction than G2019S. I1371V-expressing cells exhibited elevated LRRK2 autophosphorylation at S1292 and robust hyperphosphorylation of Rab8A and Rab10, indicating enhanced downstream signaling. These alterations impaired sterol trafficking, leading to selective depletion of membrane cholesterol without changes in total cellular cholesterol. Consequently, I1371V cells displayed increased membrane fluidity, disrupted microdomain organization, altered membrane topology, reduced caveolin-1 expression, and impaired dopamine transporter surface expression and dopamine uptake. Lipidomic profiling further revealed a broad disruption of lipid homeostasis, including reductions in cholesteryl esters, sterols, sphingolipids, and glycerophospholipids, whereas G2019S cells showed comparatively modest changes. Pharmacological intervention revealed mutation-specific responses, with the non-selective LRRK2 modulator GW5074 outperforming the kinase-selective inhibitor MLi-2 in restoring Rab8A phosphorylation, membrane integrity, and dopaminergic function. Collectively, these findings identify membrane lipid dysregulation as a central cell biological mechanism in LRRK2-associated PD and underscore the importance of variant-specific therapeutic strategies.

Keywords:  GTPase domain mutation; LRRK2; Parkinson’s disease; Rab8A/Rab10 phosphorylation; cholesterol trafficking; dopamine transporter dysfunction; membrane lipid homeostasis; variant-specific therapeutics

DOI:  https://doi.org/10.3390/cells15040342
FEBS Lett. 2026 Feb 24.

CPEB3 selectively inhibits α-synuclein aggregation without modulating TDP-43 pathology.

Ann Teres Babu, Mufeeda Farhana A, Harsha Varthini Periasamy, Vinesh Vijayan.

  Abnormal accumulation of misfolded proteins is a hallmark of neurodegenerative diseases. Amyloid aggregation of α-synuclein (α-Syn) and TAR DNA-binding protein 43 (TDP-43) contributes to Parkinson's disease and frontotemporal dementia, respectively. The heterotypic aggregates are increasingly recognized as highly cytotoxic. Given the frequent co-occurrence of α-Syn, TDP-43, and tau pathologies, we examined whether the first prion-like domain (PRD1) of CPEB3 modulates α-Syn and TDP-43 aggregation. Nuclear magnetic resonance (NMR) relaxation experiments revealed a direct interaction between PRD1 and the amyloid core of α-Syn, suppressing its aggregation, while phase separation assays showed delayed liquid-liquid phase separation (LLPS) -mediated α-Syn aggregation. In contrast, no interaction was detected with the C-terminal domain of TDP-43 (TDP-43CTD), indicating selective inhibition of α-Syn aggregation by PRD1.

Keywords:  NMR spectroscopy; Parkinson's disease; TDP‐43; aggregation inhibitor; phase separation; protein–protein interaction; α‐synuclein

DOI:  https://doi.org/10.1002/1873-3468.70308
bioRxiv. 2026 Feb 18. pii: 2026.02.13.705836. [Epub ahead of print]

Loss of calcium-binding protein Cbp53E leads to delayed repolarization of photoreceptor cells in Drosophila.

Natalie Cmejla, Celia Brekken, Justin Chilson, Regan Alexander, Natalie Cleary, Kathryn Davis, Shane Gonnelly, Eric Hawks, Glenn Jordan, Austin Link, Cynthia Ndahr, Gavin Olson, Estevan Quintana, Brandon Schultz, Katherine Scott, Sebastian Spencer, Margaret Talafuse, Jordn Wolsky, Hailey Zwirner, Rodrigo da Costa Aparecido, David S Ronderos.

Calcium functions as an important second messenger in a wide variety of intracellular processes. In photoreceptor cells, calcium is involved in activation, deactivation, and adaptation in response to light stimuli. Calcium-binding protein 53E (Cbp53E, also known as calbindin-32 or cbn), a protein with 6 EF-Hand domains thought to act as a calcium buffer, was previously identified to have elevated expression levels in the eye of drosophila. While a recent study showed that transgenic flies lacking Cbp53E have aberrant axonal arborization at the neuromuscular junction, nothing is known about the role of Cbp53E in the visual system. We performed electroretinogram (ERG) recordings on Cbp53E mutant flies to test whether eye function was affected. Here, we report that Cbp53E null mutants exhibit a prolonged repolarization (or slow termination) phenotype which can be rescued by expressing Cbp53E in photoreceptor cells. The human homologs Calbindin 2, Calbindin 1, and S100G also rescue the drosophila ERG phenotype. This supports a role for Cbp53E in regulating intracellular calcium levels of photoreceptor cells and contributing to normal sensory neuron response dynamics in vivo in drosophila and suggests a similar function in human photoreceptor cells as well.

DOI: https://doi.org/10.64898/2026.02.13.705836