bims-axbals 2025-11-23 papers

bims-axbals

Biomed News

on Axonal biology and ALS

Issue of 2025–11–23
25 papers selected by
TJ Krzystek

LINE1 RNA dysregulation impairs chromatin accessibility in C9ORF72- and TDP-43-linked ALS/FTD.
LXR agonist rescues synaptic dysfunction and degeneration in SPG3A patient-specific iPSC-derived neurons.
Non-canonical roles of lysosomes in neurons.
Integrative multiomic analysis links TDP-43-driven splicing defects to cascading proteomic disruption of ALS/FTD pathways.
Kenny mediates the recruitment of the phagophore for ubiquitin-dependent mitophagy in Drosophila neurons.
Synaptopathy in the TDP-43ΔNLS Mouse Model of Sporadic Amyotrophic Lateral Sclerosis.
Thalamus-cortex interactions drive cell type-specific cortical development in human pluripotent stem cell-derived assembloids.
Investigation of mitochondrial phenotypes in motor neurons derived by direct conversion of fibroblasts from familial ALS subjects.
Failure of lysosomal acidification and endomembrane network in neurodegeneration.
Neuromuscular dysfunction in patient-derived FUSR244RR-ALS iPSC model via axonal downregulation of neuromuscular junction proteins.
Loss of C9orf72 impacts the peripheral neuromuscular system via immune dysregulation and accelerates the progression of amyotrophic lateral sclerosis in SOD-1 mutant mice.
From molecular convergence to clinical divergence: Comparative pathogenic mechanisms and therapeutic trajectories in C9orf72-ALS/FTD and myotonic dystrophy.
Sequelae and reversal of age-dependent alterations in mitochondrial dynamics via autophagy enhancement in reprogrammed human neurons.
Skin TDP-43 pathology as a candidate biomarker for predicting amyotrophic lateral sclerosis decades prior to motor symptom onset.
Uncovering the molecular details of the 14-3-3 recruitment by mutant Sod1 species.
The lysosome and proteostatic stress at the intersection of pediatric neurological disorders and adult neurodegenerative diseases.
Multiplex neurodegeneration proteotoxicity platform reveals DNAJB6 promotes non-toxic FUS condensate gelation and inhibits neurotoxicity.
Genetic and Molecular Pathomechanisms of Amyotrophic Lateral Sclerosis and Therapeutic Perspectives – Current State of Knowledge
Co-localization of tau and TDP-43 after extracellular vesicle delivery to cells.
The sigma-1 receptor as a neurohomeostatic decision hub for GABARAP-mediated receptor trafficking and macroautophagy.
Brain Iron as a Surrogate Biomarker of Pathological TDP-43 Identifies Brain Region-Specific Signatures in Ageing, Alzheimer's Disease and Amyotrophic Lateral Sclerosis.
A fast TMT-based proteomic workflow reveals neural enrichment in neurospheres of hiPSC-derived neural stem cells.
Identifying a novel Mecp2-mediated epigenetic mechanism controlling Lonp1 in the hippocampus and its disruption by aging.
Sigma-2 Receptor Antagonism Enhances the Neuroprotective Effects of Pridopidine, a Sigma-1 Receptor Agonist, in Huntington's Disease.
Retrograde mitochondrial transport regulates mitochondrial biogenesis in zebrafish neurons.

bioRxiv. 2025 Oct 02. pii: 2025.09.30.679260. [Epub ahead of print]

LINE1 RNA dysregulation impairs chromatin accessibility in C9ORF72- and TDP-43-linked ALS/FTD.

Yini Li, Xiaoyang Dou, Yu Xiao, Zhe Zhang, Yingzhi Ye, Noelle Wright, Koping Chang, Chang Liu, Juan C Troncoso, Chuan He, Shuying Sun.

The long interspersed element-1 (LINE1) retrotransposon RNAs are abnormally elevated in various neurodegenerative disorders, but their pathogenic roles remain unclear. Here we investigated the mechanism of LINE1 RNA accumulation and its function in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) associated with C9ORF72 repeat expansion and TDP-43 loss-of-function, the leading causes of familial and sporadic forms of these neurodegenerative diseases. We show that LINE1 RNA is dysregulated due to an impaired nuclear exosome targeting (NEXT) degradation pathway. Its elevation epigenetically increases chromatin accessibility, enhancing global transcription via a retrotransposon-independent mechanism. Reducing LINE1 RNA mitigates chromosomal abnormalities and improves the survival of disease-relevant neurons. These findings uncover an essential noncoding RNA function and regulatory mechanism of LINE1 in neurons, providing insights into disease pathogenesis and highlighting potential therapeutic targets for neurodegenerative diseases.

DOI: https://doi.org/10.1101/2025.09.30.679260
Acta Neuropathol Commun. 2025 Nov 17. 13(1): 236

LXR agonist rescues synaptic dysfunction and degeneration in SPG3A patient-specific iPSC-derived neurons.

Gitika Thakur, Rutuja Dhanukate, Yongchao Mou, Priya Kunhiraman, Archana Khadilkar, Siddharth Srivastava, Julian E Alecu, Darius Ebrahimi-Fakhari, Zhenyu Chen, Craig Blackstone, Xue-Jun Li.

  Hereditary spastic paraplegias (HSPs) comprise a large, heterogeneous group of inherited disorders characterized by length-dependent axonal degeneration of corticospinal motor neurons, leading to lower extremity spasticity and gait impairment. Currently, there are no effective treatments for HSPs targeting axonal dysfunction. Our previous study showed that lipid defects in glial cells result in degeneration of iPSC-derived cortical projection neurons (PNs) in SPG3A, the most common early-onset form of HSP caused by autosomal dominant mutations in the ATL1 gene encoding atlastin-1. However, how cortical PNs degenerate and whether therapeutic compounds targeting lipid defects can effectively mitigate degeneration in human ATL1 neurons remain unclear. Here, by comparing SPG3A patient iPSC-derived neurons with control cells using RNA-sequencing, we identified synaptic dysfunction as a top-altered pathway in addition to lipid-related pathways. To examine the novel role of synaptic dysfunction in SPG3A, we generated patient-specific iPSCs from two SPG3A patients with distinct missense mutations and differentiated them into cortical PNs. We observed significant reductions of synaptic genes and proteins in cortical PNs from both SPG3A-P342S and SPG3A-M408T patient iPSCs, emphasizing synaptic dysfunction in SPG3A neurons. Calcium imaging revealed a significant reduction of activity in SPG3A cortical neurons compared to control neurons, further supporting functional deficits in SPG3A neurons. To further examine the role of these processes in HSP pathogenesis, we treated cells with LXR623, an orally bioavailable liver-X-receptor (LXR) agonist that can modulate lipid metabolism and transfer. LXR623 significantly mitigated the reduction in synaptic proteins and calcium activity and rescued axonal degeneration and apoptosis in SPG3A cortical PNs. Furthermore, analyses of lipid and synaptic genes and proteins revealed that LXR623 treatment effectively restored mRNA expression patterns for these pathways in SPG3A neurons. Taken together, our data demonstrate the role of synaptic dysfunction in degeneration of SPG3A neurons and highlight the therapeutic potential of an LXR agonist in mitigating human cortical neuron degeneration in HSP.

Keywords:  Axon degeneration; Hereditary spastic paraplegias; Lipid homeostasis; Synaptic dysfunction; iPSC

DOI:  https://doi.org/10.1186/s40478-025-02134-5
Trends Neurosci. 2025 Nov 18. pii: S0166-2236(25)00222-X. [Epub ahead of print]

Non-canonical roles of lysosomes in neurons.

Jonathan I Spencer, Yulia Sudarikova, Michael J Devine.

  Neurons are highly polarised and compartmentalised cells with organelles that are specialised to support their spatial and functional demands. This includes lysosomes, which are single-membrane-bound organelles enveloping acidic contents enriched with hydrolytic enzymes. While classically thought to be localised at the soma where they degrade waste, lysosomes have a range of dynamic nondegradative functions throughout neurons. Here, we review lysosomal dynamics and non-canonical functions in neurons, including axonal mRNA transport, mammalian target of rapamycin (mTOR) and Ca2+ signalling, neuronal remodelling, and interorganellar contact sites. We synthesise work across a range of model systems and species, providing insights from neurological diseases, where previous lysosomal research has focussed on proteostatic failure. This perspective highlights the need to better define lysosomal heterogeneity, compartmentalisation and specialisation in neurons.

Keywords:  autophagy; neurodegeneration; neuronal plasticity; synapse; trafficking

DOI:  https://doi.org/10.1016/j.tins.2025.10.009
bioRxiv. 2025 Nov 01. pii: 2025.09.29.679403. [Epub ahead of print]

Integrative multiomic analysis links TDP-43-driven splicing defects to cascading proteomic disruption of ALS/FTD pathways.

Velina Kozareva, Zhengde Liu, Keyana Blake, Yue A Qi, Sasha Rollinson, Sahba Seddighi, Mohammad Alsaidi, Stanislav Tsitkov, Mercedes Prudencio, Leonard Petrucelli, Dennis W Dickson, Anna-Leigh Brown, Pietro Fratta, Hong Joo Kim, J Paul Taylor, Michael E Ward, Ernest Fraenkel, Sarah E Kargbo-Hill.

Loss of nuclear TDP-43 is a hallmark of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Although TDP-43 is known to regulate RNA processing, including repression of cryptic exons, we currently lack a systems-level understanding of the consequences of TDP-43 loss. To address this, we generated multiomic datasets, including RNA-seq and proteomics, from human iPSC-derived neurons depleted of TDP-43. We found that differentially spliced genes, many expressing cryptic exons, had the greatest protein reductions. Surprisingly, nearly half of differentially expressed proteins were neither mis-spliced, nor differentially expressed genes; most of these also had no reported mis-splicing in seven additional post-mortem and iPSC-derived neuron datasets. Integrative network analysis identified a high-confidence disease-specific subnetwork of over 700 interacting proteins, enriched for mRNA processing, synaptic function, and autophagy. Comparison with post-mortem ALS and FTD samples revealed convergent protein and pathway disruptions. We experimentally validated network-predicted effects of cryptic splicing in ATG4B, STMN2, and DAPK1. Our analyses reveal new TDP-43-dependent molecular cascades and nominate central genes as potential ALS/FTD therapeutic targets.

DOI: https://doi.org/10.1101/2025.09.29.679403
Mol Biol Cell. 2025 Nov 19. mbcE25050235

Kenny mediates the recruitment of the phagophore for ubiquitin-dependent mitophagy in Drosophila neurons.

Hubert Osei Acheampong, Emily Rozich, Zachary Haupt, Charlee Tokarz, Mousumee Khan, Zahraa A Ghosn, Ryan Insolera.

The maintenance of healthy mitochondria is essential to neuronal homeostasis. Mitophagy is a critical mechanism that degrades damaged mitochondria, and disruption of this process is associated with neurodegenerative disease. Previous work has shown that mammalian optineurin (OPTN), a gene mutated in familial forms of amyotrophic lateral sclerosis (ALS) and glaucoma, is an adaptor to recruit autophagy machinery to mitochondria for ubiquitin-dependent mitophagy in cultured cells. However, OPTN's role in neuronal mitophagy in vivo remains largely unknown. Here, we demonstrate the Drosophila autophagy adaptor gene Kenny, a homolog of OPTN, mediates the recruitment of the phagophore to mitochondria undergoing ubiquitin-dependent mitophagy. We find that Kenny colocalizes with ubiquitinated mitochondria targeted for autophagic degradation in larval motoneurons, and is concentrated on the mitochondrial surface in areas opposed to the phagophore. Removal of Kenny in conditions of induced mitophagy eliminates the recruitment of the phagophore to ubiquitinated mitochondria and decreases mitophagic flux. In basal conditions, loss of Kenny causes accumulation of ubiquitinated mitochondria in neurons, indicative of stalled mitophagy. These phenotypes were reproduced in Kenny mutants ablating the LC3-interacting region domain. Overall, this work establishes Kenny as a functional homolog of OPTN in flies, and a mediator of neuronal mitophagy in vivo.

DOI: https://doi.org/10.1091/mbc.E25-05-0235
Eur J Neurosci. 2025 Nov;62(10): e70320

Synaptopathy in the TDP-43ΔNLS Mouse Model of Sporadic Amyotrophic Lateral Sclerosis.

Ani Ayvazian-Hancock, Emma Butler, Claire F Meehan, Gareth B Miles, Matthew J Broadhead.

Sporadic cases of amyotrophic lateral sclerosis (sALS) represent the most common form of motor neuron disease. sALS is characterised by pathological cytoplasmic inclusions of TDP-43, so-called reactive astrocyte pathology and motor neuron degeneration. Alterations in certain subpopulations of synapses between neurons are thought to be a key driver of the pathological mechanisms of ALS. However, we do not have a clear understanding of which types of synapses are impacted in ALS. Identifying vulnerable synapses affected in sALS models may provide insights into the key sites of disease pathogenesis. In this study we have performed quantitative high-resolution microscopy to survey different synapse subtypes, including excitatory (glutamatergic), inhibitory (glycinergic) and modulatory (cholinergic C-Boutons) synapses, in the spinal cord of a mouse model of sALS showing inducible TDP-43 pathology (TDP43ΔNLS) restricted to neurons. We have identified changes in cholinergic synapses and a subpopulation of excitatory synapses. Mice display robust neuronal TDP-43 pathology and evidence of TDP-43 changes at cholinergic C-boutons. We also observe no evidence of astrocytic pathology nor changes in the fraction of synapses that are contacted by astrocytes. Overall, our findings highlight the selective vulnerability of distinct synapse populations in ALS.

DOI: https://doi.org/10.1111/ejn.70320
Proc Natl Acad Sci U S A. 2025 Nov 25. 122(47): e2506573122

Thalamus-cortex interactions drive cell type-specific cortical development in human pluripotent stem cell-derived assembloids.

Masatoshi Nishimura, Shota Adachi, Tomoki Kodera, Akinori Y Sato, Ryosuke F Takeuchi, Fumitaka Osakada.

  The thalamus is pivotal for the development and function of neural circuits in the cerebral cortex. However, how thalamus-cortex interactions influence human cortical development remains unknown primarily because of the inaccessibility of the human embryonic brain. Here, we demonstrate thalamus-dependent gene expression, circuit organization, and neural activity during corticogenesis using human thalamocortical assembloids (hThCAs). Human cortical (hCOs) and thalamic organoids derived from induced pluripotent stem cells exhibited region-specific gene expression and spontaneous neuronal activity. Upon the fusion of these organoids, hThCAs reconstructed reciprocal thalamus-cortex axonal projections and synaptic connections. Transcriptomic analysis revealed thalamus-dependent acceleration of cortical maturation, with upregulation of programs linked to axon development, subplate/cortical plate identity, and activity-regulated genes. Histological analysis showed expanded progenitor pools and increased deep-layer neurons within hThCAs. Wide-field Ca2+ imaging demonstrated that wave-like activity originated in the thalamic region and propagated to the cortical region. Furthermore, two-photon Ca2+ imaging of cortical neurons revealed that synchronous activity emerged exclusively in pyramidal tract neurons and corticothalamic neurons, whereas intratelencephalic neurons remain asynchronous, highlighting cell type-specific circuit integration within hThCAs. These synchronized events were absent in isolated hCOs or in cortico-cortical assembloids, underscoring the specificity of thalamic input. Our findings suggest that diffusible thalamic cues broadly enhance progenitor expansion, while long-range thalamic input organizes cell type-specific synchronous activity. This study demonstrates the thalamus-dependent acquisition of mature cortical phenotypes in a cell type-specific manner in hThCAs, establishing developmental mechanisms linking regional interactions and cell type-specific circuit specification.

Keywords:  cell type; human brain; neural assembloid; neural circuit; synchronization

DOI:  https://doi.org/10.1073/pnas.2506573122
Cell Death Dis. 2025 Nov 21.

Investigation of mitochondrial phenotypes in motor neurons derived by direct conversion of fibroblasts from familial ALS subjects.

Evan Woo, Faiza Tasnim, Hibiki Kawamata, Giovanni Manfredi, Csaba Konrad.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of motor neurons, leading to fatal muscle paralysis. Familial forms of ALS (fALS) account for approximately 10% of cases. Alterations of mitochondrial functions have been proposed to contribute to disease pathogenesis. Here, we employed a direct conversion (DC) technique to generate induced motor neurons (iMN) from skin fibroblasts to investigate mitochondrial phenotypes in a patient-derived disease relevant cell culture system. We converted 7 control fibroblast lines and 17 lines harboring the following fALS mutations, SOD1A4V, TDP-43N352S, FUSR521G, CHCHD10R15L, and C9orf72 repeat expansion. We developed new machine learning approaches to identify iMN, analyze their mitochondrial function, and follow their fate longitudinally. Mitochondrial and energetic abnormalities were observed, but not all fALS iMN lines exhibited the same alterations. SOD1A4V, C9orf72, and TDP-43N352S iMN had increased mitochondrial membrane potential, while in CHCHD10R15L cells membrane potential was decreased. TDP-43N352S iMN displayed changes in mitochondrial morphology and increased motility. SOD1A4V, TDP-43N352S, and CHCHD10R15L iMN had increased oxygen consumption rates and altered extracellular acidification rates. FUSR521G mutants had decreased ATP/ADP ratio, suggesting impaired energy metabolism. SOD1A4V, C9orf72, and TDP-43N352S had increased, while FUSR521G had decreased mitochondrial reactive oxygen species production. We tested the viability of iMN and found decreases in survival in SOD1A4V, C9orf72, and FUSR521G, which were corrected by small molecules that target mitochondrial stress and worsened by bioenergetic stressors. Together, our findings reinforce the role of mitochondrial dysfunction in ALS and indicate that fibroblast-derived iMN may be useful to study fALS metabolic alterations. Strengths of the DC iMN approach include low cost, speed of transformation, and the preservation of epigenetic modifications. However, further refinement of the fibroblasts DC iMN technique is still needed to improve transformation efficiency, reproducibility, the relatively short lifespan of iMN, and the senescence of the parental fibroblasts.

DOI: https://doi.org/10.1038/s41419-025-08126-6
Exp Mol Med. 2025 Nov 18.

Failure of lysosomal acidification and endomembrane network in neurodegeneration.

Seo-Hyun Kim, Young-Sin Cho, Yong-Keun Jung.

Lysosomes have emerged as central hubs in the regulation of the endomembrane system, extending beyond degradation to coordinate organelle communication. Central to this regulatory role is vacuolar-type H+-ATPase (V-ATPase), a proton pump that acidifies the lysosomal lumen to enable hydrolase activity and support proteostasis. In addition to its lysosomal functions, V-ATPase influences the physiology of other organelles, including the endoplasmic reticulum (ER), Golgi apparatus and mitochondria, through both direct and indirect mechanisms involving acidification-dependent processes, such as protein folding, vesicular trafficking and stress responses. V-ATPase dysfunction compromises interorganelle communication through multiple mechanisms, including impaired calcium and lipid exchange at contact sites, disrupted organelle positioning and defective autophagic and stress signaling. In neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases, V-ATPase impairment contributes to lysosomal storage pathology, ER stress, Golgi fragmentation and mitochondrial dysfunction. ER-endolysosome tethering proteins and mitochondria-lysosome contacts are particularly sensitive to pH and trafficking defects. These disruptions result in a cascade of organelle dysfunction and contribute to disease progression. Here, in this Review, we highlight how V-ATPase governs both local lysosomal function and broader organelle network integrity, positioning it as a critical regulator of endomembrane homeostasis and a potential therapeutic target in neurodegenerative conditions.

DOI: https://doi.org/10.1038/s12276-025-01579-x
NAR Mol Med. 2025 Apr;2(2): ugaf005

Neuromuscular dysfunction in patient-derived FUSR244RR-ALS iPSC model via axonal downregulation of neuromuscular junction proteins.

Nicolai von Kügelgen, Katarzyna Ludwik, Samantha Mendonsa, Christine Römer, Erik Becher, Laura Breimann, Mara Strauch, Tommaso Mari, Sandrine Mongellaz, Binyamin Zuckerman, Fatima Efendic, Nina Grexa, Anna Oliveras-Martinez, Andrew Woehler, Matthias Selbach, Vincenzo La Bella, Igor Ulitsky, Marina Chekulaeva.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative condition characterized by the progressive degeneration of motor neurons (MNs), ultimately resulting in death due to respiratory failure. A common feature among ALS cases is the early loss of axons, pointing to defects in axonal transport and translation as initial disease indicators. ALS is associated with mutations in RNA-binding proteins, such as FUS (Fused in Sarcoma). Here, we established a FUSR244RR-ALS hiPSC-derived model that recapitulates the MN survival and muscle contractility defects characteristic of ALS patients. Analysis of the protein and mRNA expression profiles in axonal and somatodendritic compartments of ALS-afflicted and isogenic control MNs revealed a selective downregulation of proteins essential for the neuromuscular junction function in FUS-ALS axons. Furthermore, analysis of FUS CLIP and RIP data showed that FUS binds mRNAs encoding these proteins. This work shed light on the pathogenic mechanisms of ALS and emphasized the importance of axonal gene expression analysis in elucidating the mechanisms of neurodegenerative disorders.

DOI: https://doi.org/10.1093/narmme/ugaf005
J Neuroinflammation. 2025 Nov 15. 22(1): 272

Loss of C9orf72 impacts the peripheral neuromuscular system via immune dysregulation and accelerates the progression of amyotrophic lateral sclerosis in SOD-1 mutant mice.

Francesca Sironi, Massimo Tortarolo, Sabrina Mazzucchi, Laura Camporeale, Mattia Freschi, Eliana Arcadipane, Giulia De Giovanetti, Mami Kurosaki, Mineko Terao, Paola Parlanti, Paola Podini, Francesco Gentile, Valentina Bonetto, Valentina Cappello, Nilo Riva, Angelo Quattrini, Caterina Bendotti.

   BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder where neuromuscular health is central to disease progression. The degeneration of motor neurons (MNs) leads to muscle weakness and paralysis, underscoring the critical importance of neuromuscular junctions (NMJs) and axonal integrity. Among the genetic contributors to ALS, mutations in the C9orf72 gene are the most common, accounting for both ALS and frontotemporal dementia (FTD). While the role of C9orf72 has been studied across various cells and compartments, its function in the peripheral nervous system (PNS), a compartment crucial for maintaining neuromuscular connectivity in ALS,remains largely unexplored.
MAIN BODY: Our study investigates the role of C9orf72 loss-of-function in ALS, focusing on its neuromuscular effects. C9orf72 expression is localized in MNs, microglia, oligodendrocytes, and Schwann cells (SCs) in the sciatic nerve (SN), but not in astrocytes. The absence of C9orf72 in mice is associated with hypomyelination and axonal sorting defect in the SN, but not with MNs loss in lumbar spinal cord. Additionally, we identified immune dysregulation, with elevated CD8+ T cells transcript and increased major histocompatibility complex I (MHCI) expression in SCs, in association with enhanced NMJ denervation in C9orf72-deficient ALS mice, suggesting a potential contribution of immune dysregulation to disease progression. These changes contributed to NMJ denervation characterized by increase in the expression of acetylcholine receptor gamma (AChRγ). The combination of C9orf72-deficiency with the ALS-linked SOD1G93A mutation resulted in a more severe phenotype and accelerated disease progression, despite no additional spinal MN loss.
CONCLUSION: Our findings underscore the critical role of C9orf72 in maintaining neuromuscular health through its influence on myelination, immune response regulation, and NMJ integrity. Loss of C9orf72 function exacerbates ALS progression by promoting SC dysfunction and immune dysregulation. This highlights the significance of preserving normal C9orf72 function in ALS therapies through antisense oligonucleotides strategies. Furthermore, targeting immune responses and myelination pathways may offer novel avenues for ALS treatment strategies.

Keywords:  Amyotrophic lateral sclerosis; C9orf72; Immune system; Peripheral nervous system; SOD1G93A mice

DOI:  https://doi.org/10.1186/s12974-025-03597-y
Neurobiol Dis. 2025 Nov 17. pii: S0969-9961(25)00409-7. [Epub ahead of print]217 107192

From molecular convergence to clinical divergence: Comparative pathogenic mechanisms and therapeutic trajectories in C9orf72-ALS/FTD and myotonic dystrophy.

Claudia Alberti, Valeria Parente, Stefania Corti, Valeria Ada Sansone.

  Short tandem repeat expansions in C9orf72, DMPK, and CNBP genes cause amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD) and myotonic dystrophy types 1 and 2 (DM1/DM2), respectively. Despite distinct clinical phenotypes, these disorders share convergent molecular mechanisms with tissue-specific vulnerability, offering a framework to inform precision therapeutic strategies. Shared pathogenic features include nuclear RNA foci sequestering RNA-binding proteins that disrupt splicing, and repeat-associated non-AUG translation generating toxic dipeptide repeat proteins. In C9orf72, GGGGCC repeats form RNA-driven condensates, including protein-free condensates, via G-quadruplex formation. Evidence also implicates autophagy-lysosome and mitochondrial dysfunction, suggesting a potential "two-hit" loss/gain-of-function model. Clinically, C9orf72 expansions primarily affect motor neurons and frontotemporal circuits, with ALS progression typically occurring over 2-5 years. Conversely, myotonic dystrophy manifests as a muscle-predominant multisystem disorder progressing over decades. Genomic instability contributes to disease variability, with anticipation and parent-of-origin effects strongest in DM1, not confirmed in DM2 and controversial in C9orf72. Sequence interruptions modulate repeat stability and phenotype, influencing diagnostic interpretation. Therapeutic development has yielded contrasting outcomes. Antisense oligonucleotides targeting C9orf72 achieved target engagement and reduced dipeptide repeat proteins but failed clinically, potentially due to sense-strand selectivity and persistence of TDP-43 pathology. In contrast, RNA-targeting conjugates for DM1 (delpacibart etedesiran and DYNE-101) received FDA Breakthrough Therapy designation. Therapeutic success depends on tissue accessibility and addressing both shared and circuit-specific pathogenic cascades. While nuclear RNA targets appear druggable in myotonic dystrophy, the bidirectional transcription and compartmentalized pathology of C9orf72 ALS/FTD may require multi-targeted approaches for precision medicine.

Keywords:  Amyotrophic lateral sclerosis; Antisense oligonucleotide; C9orf72; CNBP; DMPK; Frontotemporal dementia; Genome editing; Myotonic dystrophy type 1; Myotonic dystrophy type 2; RNA toxicity; Toxic gain-of-function

DOI:  https://doi.org/10.1016/j.nbd.2025.107192
bioRxiv. 2025 Oct 02. pii: 2025.10.02.680077. [Epub ahead of print]

Sequelae and reversal of age-dependent alterations in mitochondrial dynamics via autophagy enhancement in reprogrammed human neurons.

Eva Klinman, Ji-Sun Kwon, Roland E Dolle, Stephen C Pak, Gary A Silverman, David H Perlmutter, Andrew S Yoo.

How aging of human neurons affects dynamics of essential organelle such as mitochondria and autophagosomes remains largely unknown. MicroRNA-induced directly reprogrammed neurons (miNs) derived from adult fibroblasts retain age-associated signatures of the donor, enabling the study of age-dependent features in human neurons, including longitudinal isogenic samples. Transcriptomic analysis revealed that neurons derived from elderly individuals are characterized by gene expression changes associated with the regulation of autophagosomes, lysosomes, and mitochondria, compared to young counterparts. To clarify these changes at the cellular level, we performed live-cell imaging of cellular organelles in miNs from donors of different ages. Older donor miNs exhibit decreased mitochondrial membrane potential, which surprisingly co-occurs with a significant increase in mitochondrial fission and fusion events. We posit that the increased fission and fusion of mitochondria may reflect age-dependent compensation for impaired mitochondrial turnover, perhaps due to changes in autophagy. We subsequently identified a significant decrease in autophagosome acidification in neurons derived from individuals >65 years compared to younger donors, and a corresponding age-dependent reduction in neuritic lysosomes resulting in fewer lysosomes available to acidify autophagosomes. This age-dependent deficit in autolysosome flux was rescued by chemically promoting autophagosome generation, which also reversed the age-dependent increase in mitochondrial fission and fusion and improved mitochondrial health. Together, this work reveals a mechanism by which aging reduces autophagic flux secondary to a loss of neuritic lysosomes, resulting in in mitochondria-intrinsic mechanisms to avoid loss of energy production.

DOI: https://doi.org/10.1101/2025.10.02.680077
bioRxiv. 2025 Oct 03. pii: 2025.04.10.648122. [Epub ahead of print]

Skin TDP-43 pathology as a candidate biomarker for predicting amyotrophic lateral sclerosis decades prior to motor symptom onset.

Fergal M Waldron, Tatiana Langerová, Aydan Rahmanova, Fiona L Read, Holly Spence, Kristine Roberts, Angus D Macleod, Samuel B Pattle, Katie Hanna, Jenna M Gregory.

The recognition that disease-associated proteinopathies can manifest in peripheral organs outside the central nervous system preceding the onset of neurological symptoms, has transformed our understanding of Parkinson's disease, in wide terms of pathogenesis, detection and diagnosis. For amyotrophic lateral sclerosis, non-motor symptoms, and non-central nervous system pathologies are gaining increased recognition but remain incompletely understood. Here, using a TDP-43 RNA aptamer and a Stathmin-2 cryptic exon transcript BaseScope TM ISH probe, we identify widespread peripheral organ TDP-43 pathology prior to motor symptom onset in a discovery cohort of ante-mortem tissues from people who went on to develop ALS. Peripheral organs exhibiting both TDP-43 toxic gain- and loss-of function include muscle, lymph node, gallbladder, colon and with notably high incidence, skin. Given the accessibility of skin as a readily biopsiable tissue, representing a promising substrate for the detection of disease-associated proteinopathies and the development of minimally invasive biomarkers, we established an extended cohort of ante-mortem skin samples for TDP-43 pathology validation and further investigation. In skin biopsies taken during life from 17 individuals who went on to develop ALS we identify TDP-43 pathology from all 17 individuals in a wide distribution of anatomical sites, up to 26.5 years before ALS diagnosis - a presymptomatic period comparable to that observed for skin α-synucleinopathy in Parkinson's disease. TDP-43 pathology was most abundant in skin biopsies from the back and shoulder, with sweat and sebaceous glands showing the highest involvement. TDP-43 pathology was also associated with structural changes. As skin α-synucleinopathy has been established as a biomarker for both the detection of Parkinson's disease and the differentiation of Parkinson's disease from multiple system atrophy, we propose that skin TDP-43 likewise holds diagnostic and discrimination potential for diseases characterised by TDP-43 proteinopathy.
Short Abstract: Peripheral manifestations of neurodegenerative disease can precede neurological symptoms and serve as biomarkers, as shown by α-synuclein in the skin of individuals who later develop Parkinson's disease. In amyotrophic lateral sclerosis (ALS), however, the distribution and diagnostic potential of peripheral TDP-43 pathology remain unclear. Using a TDP-43 RNA aptamer and a cryptic STMN2 BaseScope™ probe, we examined ante-mortem tissues from individuals who later developed ALS. In a discovery cohort, we detected widespread pre-symptomatic TDP-43 pathology across multiple organs, with skin emerging as the most consistent site. We then validated these findings in a validation cohort comprising 17 individuals, all of whom exhibited TDP-43 pathology enriched in sweat glands and structural changes detectable up to 26.5 years before ALS diagnosis. These findings establish skin as a robust and accessible site of pre-symptomatic TDP-43 pathology, supporting its potential as a minimally invasive biomarker for early diagnosis and disease stratification in ALS.
Summary: Much like skin α-synucleinopathy has transformed biomarker development in Parkinson's disease, this study identifies skin TDP-43 pathology as a promising early marker of ALS. The results open avenues for earlier diagnosis and stratification in a disease where intervention is most needed before symptoms appear.
Highlights: Presymptomatic TDP-43 pathology occurs across a range on non-CNS peripheral organ systems including skin, gastrointestinal tract and lymph nodes prior to motor symptom onset in people who went on to develop ALS.In skin, presymptomatic TDP-43 pathology is associated with structural changes and can be detected up to 26.5 years prior to motor symptoms in ALS.As for Parkinson's disease, shoulder and back represents optimal skin sampling sites for pre-symptomatic pathology in ALS.Sweat and sebaceous glands present with high levels of TDP-43 pathology, offering a promising biomarker target for early pathology detection.
One Sentence Summary: Using distinct biomarker discovery and validation ante-mortem tissue cohorts, we provide evidence of pre-symptomatic TDP-43 pathology across diverse non-CNS peripheral tissues, including skin decades before ALS symptom onset, highlighting skin TDP-43 pathology as a potential early biomarker for ALS and related TDP-43 proteinopathies.

DOI: https://doi.org/10.1101/2025.04.10.648122
Sci Rep. 2025 Nov 20. 15(1): 41091

Uncovering the molecular details of the 14-3-3 recruitment by mutant Sod1 species.

Lorenzo Di Rienzo, Ilaria Genovese, Gaia Galluzzi, Giancarlo Ruocco, Ersilia Fornetti.

Mutations in superoxide dismutase 1 (SOD1) are a major cause of familial Amyotrophic Lateral Sclerosis (ALS), promoting disease progression through metal depletion, aggregation, and abnormal protein interactions. Among proteins interacting with pathological SOD1 aggregates, 14-3-3 proteins are involved in key cellular pathways often disrupted in ALS, such as cell survival, axonal growth, and DNA repair. Their sequestration by mutant SOD1 may impair their neuroprotective functions, exacerbating disease pathology. Despite this, 14-3-3 proteins remain understudied in ALS research, presenting an opportunity for novel insights. This study employs molecular dynamics simulations to investigate structural changes in two ALS-linked SOD1 mutations, A4V and L144F, compared to wild-type SOD1. A4V is associated with a severe disease form, while L144F leads to a slower progression, allowing an analysis of different ALS severities. Using Zernike polynomials and hydropathy assessments, we identified key structural alterations that promote aggregation and aberrant interactions. Large-scale docking simulations further suggest a stable complex between mutant SOD1 and 14-3-3 proteins, confirmed through molecular dynamics analyses. By elucidating structural features driving SOD1 aggregation and pathological interactions, our findings support targeting protein-protein interactions as a potential therapeutic strategy in ALS, offering an alternative to direct aggregate inhibition.

DOI: https://doi.org/10.1038/s41598-025-25013-4
Prog Neurobiol. 2025 Nov 16. pii: S0301-0082(25)00145-5. [Epub ahead of print]255 102854

The lysosome and proteostatic stress at the intersection of pediatric neurological disorders and adult neurodegenerative diseases.

Courtney Lane-Donovan, Mercedes Paredes, Aimee W Kao.

  In the last two decades, many gene mutations have been identified that when homozygous, lead to childhood neurological disorders, but when heterozygous, result in adult-onset neurodegenerative disease. A shared feature linking these genes? They encode proteins residing in or impacting the function of the lysosome, a key organelle in macromolecular degradation and recycling whose loss leads to the inability to manage proteostatic stress. Here, we propose that lysosomes connect a subset of genetic neurological and neurodegenerative disorders as they occur in two distinct life epochs-development and aging-that endure high levels of proteostatic and other physiological stresses. In this Perspective, we highlight the differing mechanisms of three genes that exemplify this link: glucocerebrosidase A (GBA: Gaucher's disease and Parkinson's disease), progranulin (GRN: neuronal ceroid lipofuscinosis and frontotemporal dementia), and tuberous sclerosis complex 1 (TSC1: tuberous sclerosis complex and frontotemporal dementia). We discuss why neurons seem particularly vulnerable to lysosomal dysfunction and ways in which lysosomes potentially contribute to selective neuronal vulnerability. Finally, as disrupted lysosomal catabolism of macromolecules connects these diseases of the nervous system, we propose that they be jointly conceptualized as "Lysosomal Clearance Disorders."

Keywords:  Alzheimer’s disease; Dementia; Epilepsy; Gaucher’s disease; Lysosomal storage disease; Neurodegeneration; Parkinson’s disease; Proteostasis; Seizure; Selective neuronal vulnerability

DOI:  https://doi.org/10.1016/j.pneurobio.2025.102854
Nat Commun. 2025 Nov 21. 16(1): 10285

Multiplex neurodegeneration proteotoxicity platform reveals DNAJB6 promotes non-toxic FUS condensate gelation and inhibits neurotoxicity.

Samuel J Resnick, Seema Qamar, Pushya Krishna, Vladislav Korobeynikov, Hannes Ausserwoger, Alyssa Miller, Pietro Esposito, Juan A Varela, Jenny Sheng, Lei Haley Huang, Jonathon Nixon-Abell, Schuyler Melore, Chyi Wei Chung, Nino F Läubli, Sofia Kapsiani, Xuecong Li, Jingshu Wang, Nancy Zhang, Mahabub Maraj Alam, Alondra S Burguete, Theresa C Swayne, Yanyan Chen, Ya-Cheng Liao, Neil A Shneider, Michele Vendruscolo, Tuomas P J Knowles, Clemens F Kaminski, Francesco Simone Ruggeri, Gabriele S Kaminski Schierle, Peter St George-Hyslop, Alejandro Chavez.

Neurodegenerative disorders (NDDs) are a family of diseases that remain poorly treated despite their growing global health burden. To gain insight into the mechanisms and modulators of neurodegeneration, we developed a yeast-based multiplex genetic screening platform. Using this platform, 32 NDD-associated proteins are probed against a library of 132 molecular chaperones from both yeast and humans, and an unbiased set of ~900 human proteins. We identify both broadly active and specific modifiers of our various cellular models. To illustrate the translatability of this platform, we extensively characterize a potent hit from our screens, the human chaperone DNAJB6. We show that DNAJB6 modifies the toxicity and solubility of multiple amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD)-linked RNA-binding proteins (RBPs). Biophysical examination of DNAJB6 demonstrated that it co-phase separates with, and alters the behavior of FUS containing condensates by locking them into a loose gel-like state which prevents their fibrilization. Domain mapping and a deep mutational scan of DNAJB6 revealed key residues required for its activity and identified variants with enhanced activity. Finally, we show that overexpression of DNAJB6 prevents motor neuron loss and the associated microglia activation in a mouse model of FUS-ALS.

DOI: https://doi.org/10.1038/s41467-025-65178-0
Postepy Biochem. 2025 10 01. 71(3): 252-259

Genetic and Molecular Pathomechanisms of Amyotrophic Lateral Sclerosis and Therapeutic Perspectives – Current State of Knowledge

Krzysztof Kalkowski.

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease leading to progressive degeneration of motor neurons, muscle weakness and respiratory failure. Despite intensive research, the pathomechanisms of ALS have not been fully elucidated. This article presents the current state of knowledge on the genetic and molecular mechanisms of this disease, with a focus on mutations in the SOD1, C9ORF72, TARDBP, FUS, TBK1 genes, as well as recent discoveries in this area. Key pathogenetic processes are discussed, including disruption of RNA homeostasis, oxidative stress, mitochondrial dysfunction and protein aggregation. In addition, current therapeutic strategies are reviewed, including both registered drugs, such as riluzole and edaravone, and modern approaches, such as gene therapy, antisense oligonucleotides, immunotherapy and gene editing technologies, including CRISPR/Cas9. Special attention was given to clinical trials and their potential impact on future treatment options for ALS.

DOI: https://doi.org/10.18388/pb.2021_599
FEBS J. 2025 Nov 17.

Co-localization of tau and TDP-43 after extracellular vesicle delivery to cells.

Farhang Aliakbari, Kathryn Volkening, Zahra Nayeri, Aysegul Yucel Polat, Neil Donison, Jacqueline Palik, Michael J Strong.

  Perturbations in the metabolism of microtubule-associated protein tau (tau) underlie the pathology of a broad array of dementias, including chronic traumatic encephalopathy, amyotrophic lateral sclerosis (ALS) with cognitive impairment (ALSci) and approximately half of the dementias associated with frontotemporal lobar degeneration. We recently observed significantly increased hippocampal tau pathology in rats injected with pseudophosphorylated human tau (2N4R tauT175D) co-expressing an ALS-associated TAR DNA-binding protein 43 (TDP-43) mutant (TDP-43M337V) when compared to wild-type rats. To understand this mechanism, we examined whether the extracellular vesicles (EVs) derived from wild-type TDP-43 (wtTDP-43) or tau-expressing cells could transfer expression of these proteins to recipient cells, and whether co-localization of these proteins occurs. mCherry-wtTDP-43 or EGFP-tau constructs were expressed in HEK293 or SH-SY5Y cells. The secretome and EV fractions contained wtTDP-43 or 2N4R tau protein and RNA, and could transfer proteins into nontransfected cells. Co-localization was also detected in the cytosol of recipient cells. In silico modeling of tau and TDP-43 interactions suggests hydrogen bonding underlies this interaction. These studies further our understanding of the interaction between tau and TDP-43 by demonstrating their ability to co-aggregate and in providing a mechanism by which cell-cell transfer of either protein via extracellular vesicles can lead to these synergistic interactions.

Keywords:  amyotrophic lateral sclerosis; extracellular vesicles; frontotemporal lobar degeneration; neurodegeneration; tauopathy

DOI:  https://doi.org/10.1111/febs.70336
Front Mol Biosci. 2025 ;12 1673249

The sigma-1 receptor as a neurohomeostatic decision hub for GABARAP-mediated receptor trafficking and macroautophagy.

Marius Wilhelm Baeken, Fazilet Bekbulat, Hagen Körschgen, Albrecht Martin Clement, Christian Behl.

  Gamma-aminobutyric acid receptor-associated protein (GABARAP) is a multifunctional member of the autophagy-related (ATG8) protein family, playing key roles in two distinct cellular pathways: macroautophagy and plasma membrane protein trafficking. In the context of autophagy, GABARAP modulates cargo recognition and supports the maturation and fusion of autophagosomes with lysosomes, a critical step in intracellular clearance and proteostasis. Separately, GABARAP also regulates vesicular receptor protein transport from the Golgi apparatus to the plasma membrane, contributing to proper surface localization and receptor recycling. Both tasks are especially vital for neurons, where protein turnover and receptor localization are tightly linked to synaptic plasticity and neuroprotection. We recently identified a direct interaction between GABARAP and the sigma-1 receptor (σ1R), an ER-resident receptor involved in diverse cellular stress responses, mitochondrial function, and protein homeostasis. Our findings suggest that σ1R acts as an upstream regulatory hub, influencing GABARAP's functional commitment to either membrane trafficking or autophagy. Specifically, we hypothesize that ligand-dependent σ1R activation promotes GABARAP's involvement in macroautophagy at the expense of its role in membrane transport. This regulatory switch may underline part of the neuroprotective effects observed with σ1R agonists in neurodegenerative disease models, where enhanced autophagy is often beneficial. Overall, we discuss the emerging molecular crosstalk between σ1R and GABARAP, its potential impact on neuronal homeostasis, and how σ1R's pharmacological modulation might be leveraged to bias GABARAP function toward autophagy in diseases such as amyotrophic lateral sclerosis, Huntington's, Parkinson's, and Alzheimer's disease.

Keywords:  GABARAP; GABAa receptor; LIR; autophagy; sigma-1 receptor

DOI:  https://doi.org/10.3389/fmolb.2025.1673249
bioRxiv. 2025 Oct 03. pii: 2025.10.02.680028. [Epub ahead of print]

Brain Iron as a Surrogate Biomarker of Pathological TDP-43 Identifies Brain Region-Specific Signatures in Ageing, Alzheimer's Disease and Amyotrophic Lateral Sclerosis.

Fergal M Waldron, Holly Spence, Orjona Stella Taso, Fiona L Read, Irika R Sinha, Katherine E Irwin, Philip C Wong, Jonathan P Ling, Jenna M Gregory.

Background: TDP-43 pathology is a defining feature of several neurodegenerative diseases, but its prevalence and regional distribution in ageing and disease are not well characterised. We investigated the burden of brain TDP-43 pathology across ageing, Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS), and examined ferritin as a region-specific correlate of TDP-43 pathology.
Methods: Pathological TDP-43 was detected using an HDGFL2 cryptic exon in situ hybridisation probe and a TDP-43 RNA aptamer, providing greater sensitivity and specificity than antibody-based approaches. Amygdala, hippocampus, and frontal cortex tissue was analysed from non-neurological controls (ages 40-80), AD cases, and ALS cases. Ferritin (as a proxy for iron accumulation) was quantified in parallel to assess its association with TDP-43 pathology.
Findings: TDP-43 pathology was detectable from the fourth decade of life, with a 4.5-fold increase in hippocampal involvement after age 60 years. In AD, pathology was present in 90% of cases and distinguished from ageing by selective amygdala involvement. In ALS, TDP-43 pathology was nearly ubiquitous across all regions studied. Regional ferritin strongly predicted TDP-43 burden: amygdala ferritin explained 87% of TDP-43 variance in ALS and 66% in AD, while hippocampal ferritin differentiated AD from controls. Across AD, ferritin explained between 43-81% of regional TDP-43 variance.
Interpretation: TDP-43 brain pathology emerges in midlife with increased involvement after age 60 years, exhibits disease-specific regional signatures in AD and ALS, and is closely linked to ferritin accumulation. As TDP-43 confers a worse prognosis in AD, the capacity of ferritin, detectable with iron-sensitive MRI, to serve as a proxy for regional TDP-43 burden highlights its promise as a biomarker for disease stratification and prognosis.
Short Abstract: Here we show that pathological TDP-43 emerges during normal ageing from the fourth decade of life, with a 4.5-fold increase in hippocampal involvement after 60 years. In Alzheimer's disease (AD), TDP-43 pathology was present in 90% of cases and distinguished from ageing by disproportionate amygdala involvement, while in amyotrophic lateral sclerosis (ALS) it was nearly ubiquitous across hippocampus, amygdala, and frontal cortex. Using sensitive detection tools, we demonstrate that region-specific ferritin strongly predicts TDP-43 burden: amygdala ferritin explained 87% of variance in ALS and 66% in AD, while hippocampal ferritin differentiated AD from controls. Across AD, ferritin levels in all three regions explained 43-81% of TDP-43 variance. As TDP-43 pathology confers a worse prognosis in AD, the ability of ferritin, quantifiable with iron-sensitive MRI, to serve as a proxy for regional TDP-43 burden highlights its potential as a biomarker for disease stratification and prognostic assessment.
Highlights: TDP-43 brain pathology occurs in normal ageing from early in the fourth decade, characterised by a 4.5-fold increase in hippocampus pathology from the sixth decade.TDP-43 brain pathology is detectable in 90% of AD cases, with a disease-signature of increased amygdala pathology relative to age-matched controls.In ALS, TDP-43 is nearly ubiquitous in amygdala, hippocampus and frontal cortex.Hippocampus high brain ferritin distinguishes AD from and age-matched controlsBrain ferritin is a brain region-specific marker of TDP-43 pathology in ageing and disease, with amygdala ferritin explaining 87% of the variance in amygdala TDP-43 pathology in ALS, and 66% of amygdala TDP-43 pathology in ADIn AD, ferritin levels for all three brain regions explain between 43-81% of variance in their TDP-43 pathology levels.

DOI: https://doi.org/10.1101/2025.10.02.680028
J Proteomics. 2025 Nov 16. pii: S1874-3919(25)00195-2. [Epub ahead of print] 105568

A fast TMT-based proteomic workflow reveals neural enrichment in neurospheres of hiPSC-derived neural stem cells.

Pedro de Lima Muniz, Michele Rodrigues Martins, Livia Goto-Silva, Leticia Rocha Quintino Souza, Wassali Valadares, Fábio César Sousa Nogueira, Stevens Rehen, Guillaume Nugue, Magno Junqueira.

  Three-dimensional (3D) neural spheroids, or neurospheres, generated from human induced pluripotent stem cell (hiPSC)-derived neural stem cells (NSCs) more accurately recapitulate the microenvironmental cues of neural tissue compared to traditional two-dimensional (2D) monolayers. However, comparative omics-based characterizations of these models remain limited. Here, we present a streamlined and scalable TMT-based quantitative proteomics workflow to contrast the proteomic landscapes of hiPSC-derived NSCs cultured in 2D monolayers versus 3D neurospheres. A total of 1576 proteins were identified in an unfractionated LC-MS/MS of 68 min, with 542 showing significant differential abundance between groups. Neurospheres exhibited enrichment in neural-related pathways, such as synaptic signaling, neurotrophin signaling, cytoskeletal organization and vesicle trafficking, while monolayers enriched for multipotency features, such as general metabolic activity. Cell-type enrichment analyses confirmed increased neuronal identity in neurospheres, including elevated levels of markers associated with neuronal maturation. Our results demonstrate that 3D culture of NSCs induces a proteomic shift toward a more mature neural phenotype, which was validated by immunofluorescence microscopy. This rapid, multiplexed proteomic approach enables high-content molecular profiling suitable for drug screening and personalized medicine applications. SIGNIFICANCE: The present work contributes to the molecular and biological understanding of iPSC-derived neurospheres by exploring the proteome of this model. Neurospheres are a culture model of great potential and applicability in neurobiology research and personalized medicine, which still lacks a robust omic characterization. By studying neurospheres, we also work with a 3D culture model generated in vitro, avoiding the use of primary neural cells culture and animal models. Our fast method is relevant to single-cell proteomics, personalized medicine and screening assays.

Keywords:  3D models; Comparative proteomics; Fast and scalable; Neural stem cells; Neurospheres; TMT

DOI:  https://doi.org/10.1016/j.jprot.2025.105568
Sci Rep. 2025 Nov 19. 15(1): 40887

Identifying a novel Mecp2-mediated epigenetic mechanism controlling Lonp1 in the hippocampus and its disruption by aging.

Jesús Llanquinao-Sandoval, Karina A Cicali, Claudia Jara, Carlos Vigil-Vásquez, Marcela K Sjöberg-Herrera, Micaela Ricca, Sebastian Valenzuela, Alejandra Loyola, Marcello Pinti, Andreas Schüller, Bredford Kerr, Cheril Tapia-Rojas.

  Aging is characterized by a progressive decline in cellular function, including the hippocampus, a brain region crucial for learning and memory. Mitochondrial dysfunction is a hallmark of aging, critical for hippocampal deterioration. The mitochondrial protease Lonp1 is a key regulator of mitochondrial proteostasis, and its diminished expression or activity has been implicated in age-related dysfunction in non-neuronal cells. However, despite its essential role in maintaining mitochondrial function, the transcriptional regulation of Lonp1 remains poorly understood. Evidence suggests that Lonp1 is subject to epigenetic control via changes in DNA methylation patterns. Mepc2, a DNA-methylation reader, acts as a transcriptional regulator highly expressed in neurons, either activating or repressing gene expression. Yet, its role in the mitochondria of aged hippocampus and its potential role as Lonp1 regulator haven't been explored. Here, we investigated Lonp1 expression and its epigenetic regulation by Mecp2 in the hippocampus of aged SAMP8 mice. We identified CpG islands in the Lonp1 promoter, near the transcription start site, where DNA methylation levels increase in aged hippocampal tissue. Chromatin immunoprecipitation revealed that Mecp2 directly binds to the Lonp1 promoter, with a significant reduction in binding observed in aged mice, correlating with increased Lonp1 mRNA levels. These findings show, for the first time, that Mecp2 is a transcriptional repressor of Lonp1 in the hippocampus. Additionally, unlike humans expressing three isoforms of Lonp1, mice exhibit only the full-length mitochondrial isoform. Interestingly, despite increased Lonp1 mRNA levels in aged mice, their protein levels were significantly decreased in the aged hippocampus. This unexpected result is, at least in part, explained by the enhanced Lonp1 protein degradation by the lysosome. Together, our findings reveal a novel mechanism that drives Lonp1 expression, linking Mecp2-mediated epigenetic regulation to age-related mitochondrial dysfunction. This study reveals Mecp2 and Lonp1 as potential therapeutic targets for mitochondrial proteostasis in aging.

Keywords:  Aging; Epigenetics; Hippocampus; Lonp1; Mecp2

DOI:  https://doi.org/10.1038/s41598-025-24766-2
Mol Neurobiol. 2025 Nov 21. 63(1): 121

Sigma-2 Receptor Antagonism Enhances the Neuroprotective Effects of Pridopidine, a Sigma-1 Receptor Agonist, in Huntington's Disease.

Jing Jin, Randal Hand, May Meltzer, Carmen Abate, Michal Geva, Michael R Hayden, Christopher A Ross.

  Pridopidine is a selective sigma-1 receptor (S1R) agonist in clinical development for Huntington's Disease (HD) and Amyotrophic Lateral Sclerosis (ALS). Activation of the S1R by pridopidine is neuroprotective in multiple preclinical models of neurodegenerative disease. The sigma-2 receptor (S2R) is evolutionarily and structurally unique from the S1R. Nevertheless, the S1R and S2R share an overlapping yet distinct ligand binding profile. Inhibition of the S2R is neuroprotective and S2R antagonists are in clinical development for Alzheimer's Disease (AD), ⍺-synucleinopathies, and dry age-related macular degeneration. In this study, we hypothesized that simultaneous activation of the S1R by pridopidine and inhibition of the S2R by the selective S2R antagonist FA10 might provide enhanced protection against mutant huntingtin (mHTT) expression in an in vitro model of neurodegeneration. Consistent with previous studies, pridopidine reduced neuronal cell death in a mouse primary neuron mHTT model. Similarly, we found that inhibition of the S2R by FA10 was also sufficient to protect against mHTT induced neurodegeneration in this model. The combination treatment of pridopidine and FA10 achieved greater efficacy than either compound alone, even at lower concentrations. The combination of these compounds may allow for lower efficacious doses leading to improved safety profiles and reduced off-target effects. This novel combinatorial approach, in which the S1R is activated while simultaneously inhibiting the S2R may prove to be a highly effective therapeutic strategy for HD and other neurodegenerative diseases.

Keywords:  Huntington's disease; Pridopidine; Sigma-1 receptor; Sigma-2 receptor

DOI:  https://doi.org/10.1007/s12035-025-05393-4
bioRxiv. 2025 Oct 01. pii: 2025.09.29.679307. [Epub ahead of print]

Retrograde mitochondrial transport regulates mitochondrial biogenesis in zebrafish neurons.

Angelica E Lang, Chris Stein, Catherine M Drerup.

To maintain a healthy mitochondrial population in a long-lived cell like a neuron, mitochondria must be continuously replenished through the process of mitochondrial biogenesis. Because the majority of mitochondrial proteins are nuclear encoded, mitochondrial biogenesis requires nuclear sensing of mitochondrial population health and function. This can be a challenge in a large, compartmentalized cell like a neuron in which a large portion of the mitochondrial population is in neuronal compartments far from the nucleus. Using in vivo assessments of mitochondrial biogenesis in zebrafish neurons, we determined that mitochondrial transport between distal axonal compartments and the cell body is required for sustained mitochondrial biogenesis. Estrogen-related receptor transcriptional activation links transport with mitochondrial gene expression. Together, our data support a role for retrograde feedback between axonal mitochondria and the nucleus for regulation of mitochondrial biogenesis in neurons.

DOI: https://doi.org/10.1101/2025.09.29.679307