bims-axbals 2025-03-02 papers

bims-axbals

Biomed News

on Axonal biology and ALS

Issue of 2025–03–02
38 papers selected by
TJ Krzystek, ALS Therapy Development Institute

Edaravone mitigates TDP-43 mislocalization in human amyotrophic lateral sclerosis neurons with potential implication of the SIRT1-XBP1 pathway.
Epigenetic regulation of TDP-43: potential implications for amyotrophic lateral sclerosis.
Amyotrophic lateral sclerosis caused by hexanucleotide repeat expansions in C9orf72: from genetics to therapeutics.
pTDP-43 levels correlate with cell type-specific molecular alterations in the prefrontal cortex of C9orf72 ALS/FTD patients.
Neuronal TDP-43 aggregation drives changes in microglial morphology prior to immunophenotype in amyotrophic lateral sclerosis.
TDP-43 pathology is sufficient to drive axon initial segment plasticity and hyperexcitability of spinal motoneurones in vivo in the TDP43-ΔNLS model of Amyotrophic Lateral Sclerosis.
G-Quadruplex Structures Formed by Human Telomere and C9orf72 GGGGCC Repeats.
Neuronal polyunsaturated fatty acids are protective in ALS/FTD.
Improving ALS detection and cognitive impairment stratification with attention-enhanced deep learning models.
TDP-43 Aggregate Seeding Impairs Autoregulation and Causes TDP-43 Dysfunction.
Spatiotemporal proteomics reveals the biosynthetic lysosomal membrane protein interactome in neurons.
Fructose-2,6-bisphosphate restores TDP-43 pathology-driven genome repair deficiency in motor neuron diseases.
Metabolic rate and insulin-independent glucose uptake increase in a TDP-43Q331K mouse model of amyotrophic lateral sclerosis.
Tsc1 deletion in Purkinje neurons disrupts the axon initial segment, impairing excitability and cerebellar function.
TDP-43 as a potential retinal biomarker for neurodegenerative diseases.
Modeling ALS with Patient-Derived iPSCs: Recent Advances and Future Potentials.
An immunomodulatory encapsulation system to deliver human iPSC-derived dopaminergic neuron progenitors for Parkinson's disease treatment.
TANGO2 is an acyl-CoA binding protein.
TC10 on endosomes regulates the local balance between microtubule stability and dynamics through the PAK2-JNK pathway and promotes axon outgrowth.
Hippocampal mitophagy alterations in MAPT-associated frontotemporal dementia with parkinsonism.
Optineurin overexpression ameliorates neurodegeneration through regulating neuroinflammation and mitochondrial quality in a murine model of amyotrophic lateral sclerosis.
Peripherin, A New Promising Biomarker in Neurological Disorders.
Advancements in genetic research and RNA therapy strategies for amyotrophic lateral sclerosis (ALS): current progress and future prospects.
Disruption of G3BP1 granules promotes mammalian CNS and PNS axon regeneration.
Mitochondrial dynamics and quality control regulate proteostasis in neuronal ischemia-reperfusion.
The tau isoform 1N4R confers vulnerability of MAPT knockout human iPSC-derived neurons to amyloid beta and phosphorylated tau-induced neuronal dysfunction.
Overcoming Neuroanatomical Mapping and Computational Barriers in Human Brain Synaptic Architecture.
Autophagy in Tissue Repair and Regeneration.
Human iPSC-Derived Muscle Cells as a New Model for Investigation of EDMD1 Pathogenesis.
Alterations of PINK1-PRKN signaling in mice during normal aging.
Human striatal progenitor cells that contain inducible safeguards and overexpress BDNF rescue Huntington's disease phenotypes.
Structural Analysis of Cerebral Organoids Using Confocal Microscopy and Transmission/Scanning Electron Microscopy.
Lysosome-Mitochondrial Crosstalk in Cellular Stress and Disease.
Axonal Mechanotransduction Drives Cytoskeletal Responses to Physiological Mechanical Forces.
The spectrum of lysosomal stress and damage responses: from mechanosensing to inflammation.
Optic nerve injury impairs intrinsic mechanisms underlying electrical activity in a resilient retinal ganglion cell.
Reversing lysosomal dysfunction to treat PAH.
Neuronal autophagy in the control of synapse function.

Free Radic Biol Med. 2025 Feb 25. pii: S0891-5849(25)00012-7. [Epub ahead of print]230 283-293

Edaravone mitigates TDP-43 mislocalization in human amyotrophic lateral sclerosis neurons with potential implication of the SIRT1-XBP1 pathway.

Satsuki Mikuriya, Tomo Takegawa-Araki, Makoto Tamura.

  Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive motor neuron loss along with pathological mislocalization of TAR DNA-binding protein 43 (TDP-43), a protein implicated in RNA metabolism. Although edaravone, a free-radical scavenger, has been approved for ALS treatment, its precise mechanism of action is not fully understood, particularly in relation to TDP-43 pathology. Here, we investigated the effects of edaravone on induced pluripotent stem cell (iPSC)-derived motor neurons in a patient with ALS harboring a TDP-43 mutation. Our results demonstrated that edaravone significantly attenuated neurodegeneration, as evidenced by neurite preservation, neuronal cell death reduction, and correction of aberrant cytoplasmic localization of TDP-43. These neuroprotective effects were not observed with vitamin C, indicating a unique mechanism of action for edaravone, distinct from its antioxidative properties. RNA sequencing revealed that edaravone rapidly modulated gene expression, including protein quality control pathway, such as the ubiquitin-proteasome system. Further analysis identified X-box binding protein (XBP1), a key regulator of the endoplasmic reticulum stress response, as a critical factor in the therapeutic effects of edaravone. This study suggests that edaravone may offer a multifaceted therapeutic approach for ALS by targeting oxidative stress and TDP-43 mislocalization through distinct molecular pathways.

Keywords:  Amyotrophic lateral sclerosis; Antioxidants; Edaravone; TDP-43

DOI:  https://doi.org/10.1016/j.freeradbiomed.2025.01.012
Front Mol Med. 2025 ;5 1530719

Epigenetic regulation of TDP-43: potential implications for amyotrophic lateral sclerosis.

D Y Mengistu, M Terribili, C Pellacani, L Ciapponi, M Marzullo.

  Amyotrophic lateral sclerosis (ALS) is a multifactorial neurodegenerative disease characterized by the progressive degeneration of motor neurons. One of the key pathogenic factors implicated in ALS is TDP-43 (TAR DNA-binding protein 43), an RNA-binding protein encoded by the TARDBP gene. Under normal physiological conditions, TDP-43 predominantly resides in the nucleus, where it plays a critical role in regulating gene expression, alternative splicing, RNA transport, and stability. In ALS, TDP-43 undergoes pathological mislocalization from the nucleus to the cytoplasm, disrupting its normal function and contributing to disease progression. The nuclear loss of TDP-43 leads to widespread dysregulation of RNA metabolism. Moreover, mislocalized TDP-43 aggregates in the cytoplasm, acquires toxic properties that sequester essential RNA molecules and proteins. Importantly, deviations in TDP-43 levels, whether excessive or reduced, can lead to cellular dysfunction, and contribute to disease progression, highlighting the delicate balance required for neuronal health. Emerging evidence suggests that epigenetic mechanisms may play a crucial role in regulating TARDBP expression and, consequently, TDP-43 cellular levels. Epigenetic modifications such as DNA methylation, histone modifications, and non-coding RNAs are increasingly recognized as modulators of gene expression and cellular function in neurodegenerative diseases, including ALS. Dysregulation of these processes could contribute to aberrant TARDBP expression, amplifying TDP-43-associated pathologies. This review explores and summarizes the recent findings on how specific epigenetic modifications influence TDP-43 expression and discusses their possible implications for disease progression.

Keywords:  ALS (amyotrophic lateral sclerosis); DNA methylation; TDP-43; epigenetic regulation; histone modifications; microRNA

DOI:  https://doi.org/10.3389/fmmed.2025.1530719
Lancet Neurol. 2025 Mar;pii: S1474-4422(25)00026-2. [Epub ahead of print]24(3): 261-274

Amyotrophic lateral sclerosis caused by hexanucleotide repeat expansions in C9orf72: from genetics to therapeutics.

Sarah Mizielinska, Guillaume M Hautbergue, Tania F Gendron, Marka van Blitterswijk, Orla Hardiman, John Ravits, Adrian M Isaacs, Rosa Rademakers.

GGGGCC repeat expansions in C9orf72 are a common genetic cause of amyotrophic lateral sclerosis in people of European ancestry; however, substantial variability in the penetrance of the mutation, age at disease onset, and clinical presentation can complicate diagnosis and prognosis. The repeat expansion is bidirectionally transcribed in the sense and antisense directions into repetitive RNAs and translated into dipeptide repeat proteins, and both accumulate in the cortex, cerebellum, and the spinal cord. Furthermore, neuropathological aggregates of phosphorylated TDP-43 are observed in motor cortex and other cortical regions, and in the spinal cord of patients at autopsy. C9orf72 repeat expansions can also cause frontotemporal dementia. The GGGGCC repeat induces a complex interplay of loss-of-function and gain-of-function pathological mechanisms. Clinical trials using antisense oligonucleotides to target the GGGGCC repeat RNA have not been successful, potentially because they only target a single gain-of-function mechanism. Novel therapeutic approaches targeting the DNA repeat expansion, multiple repeat-derived RNA species, or downstream targets of TDP-43 dysfunction are, however, on the horizon, together with the development of diagnostic and prognostic biomarkers.

DOI: https://doi.org/10.1016/S1474-4422(25)00026-2
Proc Natl Acad Sci U S A. 2025 Mar 04. 122(9): e2419818122

pTDP-43 levels correlate with cell type-specific molecular alterations in the prefrontal cortex of C9orf72 ALS/FTD patients.

Hsiao-Lin V Wang, Jian-Feng Xiang, Chenyang Yuan, Austin M Veire, Tania F Gendron, Melissa E Murray, Malú G Tansey, Jian Hu, Marla Gearing, Jonathan D Glass, Peng Jin, Victor G Corces, Zachary T McEachin.

  Repeat expansions in the C9orf72 gene are the most common genetic cause of amyotrophic lateral sclerosis and familial frontotemporal dementia (ALS/FTD). To identify molecular defects that take place in the dorsolateral frontal cortex of patients with C9orf72 ALS/FTD, we compared healthy controls with C9orf72 ALS/FTD donor samples staged based on the levels of cortical phosphorylated TAR DNA binding protein (pTDP-43), a neuropathological hallmark of disease progression. We identified distinct molecular changes in different cell types that take place during FTD development. Loss of neurosurveillance microglia and activation of the complement cascade take place early, when pTDP-43 aggregates are absent or very low, and become more pronounced in late stages, suggesting an initial involvement of microglia in disease progression. Reduction of layer 2-3 cortical projection neurons with high expression of CUX2/LAMP5 also occurs early, and the reduction becomes more pronounced as pTDP-43 accumulates. Several unique features were observed only in samples with high levels of pTDP-43, including global alteration of chromatin accessibility in oligodendrocytes, microglia, and astrocytes; higher ratios of premature oligodendrocytes; increased levels of the noncoding RNA NEAT1 in astrocytes and neurons, and higher amount of phosphorylated ribosomal protein S6. Our findings reveal progressive functional changes in major cell types found in the prefrontal cortex of C9orf72 ALS/FTD patients that shed light on the mechanisms underlying the pathology of this disease.

Keywords:  amyotrophic lateral sclerosis; chromatin; epigenetics; frontotemporal dementia; neurodegeneration

DOI:  https://doi.org/10.1073/pnas.2419818122
Acta Neuropathol Commun. 2025 Feb 21. 13(1): 39

Neuronal TDP-43 aggregation drives changes in microglial morphology prior to immunophenotype in amyotrophic lateral sclerosis.

Molly E V Swanson, Miran Mrkela, Clinton Turner, Maurice A Curtis, Richard L M Faull, Adam K Walker, Emma L Scotter.

  Microglia are the innate immune cells of the brain with the capacity to react to damage or disease. Microglial reactions can be characterised in post-mortem tissues by assessing their pattern of protein expression, or immunophenotypes, and cell morphologies. We recently demonstrated that microglia have a phagocytic immunophenotype in early-stage ALS but transition to a dysfunctional immunophenotype by end stage, and that these states are driven by TAR DNA-binding protein 43 (TDP-43) aggregation in the human brain. However, it remains unclear how microglial morphologies are changed in ALS. Here we examine the relationship between microglial immunophenotypes and morphologies, and TDP-43 pathology in motor cortex tissue from people with ALS and from a TDP-43-driven ALS mouse model. Post-mortem human brain tissue from 10 control and 10 ALS cases was analysed alongside brain tissue from the bigenic NEFH-tTA/tetO-hTDP-43∆NLS (rNLS) mouse model of ALS at distinct disease stages. Sections were immunohistochemically labelled for microglial markers (HLA-DR, CD68, and Iba1) and phosphorylated TDP-43 (pTDP-43). Single-cell microglial HLA-DR, CD68, and Iba1 average intensities, and morphological features (cell body area, process number, total outgrowth, and branch number) were measured using custom image analysis pipelines. In human ALS motor cortex, we identified a significant change in microglial morphologies from ramified to hypertrophic, which was associated with increased Iba1 and CD68 levels. In the rNLS mouse motor cortex, the microglial morphologies changed from ramified to hypertrophic and increased Iba1 levels occurred in parallel with pTDP-43 aggregation, prior to increases in CD68 levels. Overall, the evidence presented in this study demonstrates that microglia change their morphologies prior to immunophenotype changes. These morphological changes may prime microglia near neurons with pTDP-43 aggregation for phagocytosis, in turn triggering immunophenotype changes; first, to a phagocytic state then to a dysfunctional one.

Keywords:  Amyotrophic lateral sclerosis; CD68; Dystrophic; Hypertrophic; Iba1; Microglia; Ramified; TDP-43

DOI:  https://doi.org/10.1186/s40478-025-01941-0
Acta Neuropathol Commun. 2025 Feb 24. 13(1): 42

TDP-43 pathology is sufficient to drive axon initial segment plasticity and hyperexcitability of spinal motoneurones in vivo in the TDP43-ΔNLS model of Amyotrophic Lateral Sclerosis.

Svetlana Djukic, Zhenxiang Zhao, Lasse Mathias Holmsted Jørgensen, Anna Normann Bak, Dennis Bo Jensen, Claire Francesca Meehan.

  A hyperexcitability of the motor system is consistently observed in Amyotrophic Lateral Sclerosis (ALS) and has been implicated in the disease pathogenesis. What drives this hyperexcitability in the vast majority of patients is unknown. This is important to know as existing treatments simply reduce all neuronal excitability and fail to distinguish between pathological changes and important homeostatic changes. Understanding what drives the initial pathological changes could therefore provide better treatments. One challenge is that patients represent a heterogeneous population and the vast majority of cases are sporadic. One pathological feature that almost all (~97%) cases (familial and sporadic) have in common are cytoplasmic aggregates of the protein TDP-43 which is normally located in the nucleus. In our experiments we investigated whether this pathology was sufficient to increase neuronal excitability and the mechanisms by which this occurs. We used the TDP-43(ΔNLS) mouse model which successfully recapitulates this pathology in a controllable way. We used in vivo intracellular recordings in this model to demonstrate that TDP-43 pathology is sufficient to drive a severe hyper-excitability of spinal motoneurones. Reductions in soma size and a lengthening and constriction of axon initial segments were observed, which would contribute to enhanced excitability. Resuppression of the transgene resulted in a return to normal excitability parameters by 6-8 weeks. We therefore conclude that TDP-43 pathology itself is sufficient to drive a severe but reversible hyperexcitability of spinal motoneurones.

Keywords:  Amyotrophic Lateral Sclerosis; Excitability; Motoneurone; TDP-43

DOI:  https://doi.org/10.1186/s40478-025-01934-z
Int J Mol Sci. 2025 Feb 13. pii: 1591. [Epub ahead of print]26(4):

G-Quadruplex Structures Formed by Human Telomere and C9orf72 GGGGCC Repeats.

Bing Yan, Monica Ching Suen, Naining Xu, Chao Lu, Changdong Liu, Guang Zhu.

  G-quadruplexes (G4s) are unique nucleic acid structures composed of guanine-rich (G-rich) sequences that can form diverse topologies based on the arrangement of their four strands. G4s have attracted attention for their potential roles in various biological processes and human diseases. In this review, we focus on the G4 structures formed by human telomeric sequences, (GGGTTA)n, and the hexanucleotide repeat expansion, (GGGGCC)n, in the first intron region of the chromosome 9 open reading frame 72 (C9orf72) gene, highlighting their structural diversity and biological significance. Human telomeric G4s play crucial roles in telomere retention and gene regulation. In particular, we provide an in-depth summary of known telomeric G4s and focus on our recently discovered chair-type conformation, which exhibits distinct folding patterns. The chair-type G4s represent a novel folding pattern with unique characteristics, expanding our knowledge of telomeric G4 structural diversity and potential biological functions. Specifically, we emphasize the G4s formed by the (GGGGCC)n sequence of the C9orf72 gene, which represents the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The thorough structural analysis in this review advances our comprehension of the disease mechanism and provides valuable insights into developing targeted therapeutic strategies in ALS/FTD.

Keywords:  ALS/FTD; C9orf72; G-quadruplex; neurodegenerative disease; telomere

DOI:  https://doi.org/10.3390/ijms26041591
Nat Neurosci. 2025 Feb 25.

Neuronal polyunsaturated fatty acids are protective in ALS/FTD.

Ashling Giblin, Alexander J Cammack, Niek Blomberg, Sharifah Anoar, Alla Mikheenko, Mireia Carcolé, Magda L Atilano, Alex Hull, Dunxin Shen, Xiaoya Wei, Rachel Coneys, Lele Zhou, Yassene Mohammed, Damien Olivier-Jimenez, Lian Y Wang, Kerri J Kinghorn, Teresa Niccoli, Alyssa N Coyne, Rik van der Kant, Tammaryn Lashley, Martin Giera, Linda Partridge, Adrian M Isaacs.

Here we report a conserved transcriptomic signature of reduced fatty acid and lipid metabolism gene expression in a Drosophila model of C9orf72 repeat expansion, the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD), and in human postmortem ALS spinal cord. We performed lipidomics on C9 ALS/FTD Drosophila, induced pluripotent stem (iPS) cell neurons and postmortem FTD brain tissue. This revealed a common and specific reduction in phospholipid species containing polyunsaturated fatty acids (PUFAs). Feeding C9 ALS/FTD flies PUFAs yielded a modest increase in survival. However, increasing PUFA levels specifically in neurons of C9 ALS/FTD flies, by overexpressing fatty acid desaturase enzymes, led to a substantial extension of lifespan. Neuronal overexpression of fatty acid desaturases also suppressed stressor-induced neuronal death in iPS cell neurons of patients with both C9 and TDP-43 ALS/FTD. These data implicate neuronal fatty acid saturation in the pathogenesis of ALS/FTD and suggest that interventions to increase neuronal PUFA levels may be beneficial.

DOI: https://doi.org/10.1038/s41593-025-01889-3
Sci Rep. 2025 Feb 27. 15(1): 7045

Improving ALS detection and cognitive impairment stratification with attention-enhanced deep learning models.

Yuqing Xia, Jenna M Gregory, Fergal M Waldron, Holly Spence, Marta Vallejo.

  Amyotrophic lateral sclerosis (ALS) is a fatal neurological disease marked by motor deterioration and cognitive decline. Early diagnosis is challenging due to the complexity of sporadic ALS and the lack of a defined risk population. In this study, we developed Miniset-DenseSENet, a convolutional neural network combining DenseNet121 with a Squeeze-and-Excitation attention mechanism, using 190 autopsy brain images from the Gregory Laboratory at the University of Aberdeen. The model distinguishes controls, ALS patients with no cognitive impairment, and ALS patients with cognitive impairment (ALS-frontotemporal dementia) with 97.37% accuracy, addressing a significant challenge in overlapping neurodegenerative disorders involving TDP-43 proteinopathy. Miniset-DenseSENet outperformed other transfer learning models, achieving a sensitivity of 1 and specificity of 0.95. These findings suggest that integrating transfer learning and attention mechanisms into neuroimaging can enhance diagnostic accuracy, enabling earlier ALS detection and improving patient stratification. This model has the potential to guide clinical decisions and support personalied therapeutic strategies.

Keywords:  Amyotrophic lateral sclerosis; Attention mechanisms; Cognitive impairment; TDP-43 protein; Transfer learning

DOI:  https://doi.org/10.1038/s41598-025-90881-9
bioRxiv. 2025 Feb 12. pii: 2025.02.11.637743. [Epub ahead of print]

TDP-43 Aggregate Seeding Impairs Autoregulation and Causes TDP-43 Dysfunction.

Lohany Dias Mamede, Miwei Hu, Amanda R Titus, Jaime Vaquer-Alicea, Rachel L French, Marc I Diamond, Timothy M Miller, Yuna M Ayala.

The aggregation, cellular mislocalization and dysfunction of TDP-43 are hallmarks of multiple neurodegenerative disorders. We find that inducing TDP-43 aggregation through prion-like seeding gradually diminishes normal TDP-43 nuclear localization and function. Aggregate-affected cells show signature features of TDP-43 loss of function, such as DNA damage and dysregulated TDP-43-target expression. We also observe strong activation of TDP-43-controlled cryptic exons in cells, including human neurons treated with proteopathic seeds. Furthermore, aggregate seeding impairs TDP-43 autoregulation, an essential mechanism controlling TDP-43 homeostasis. Interestingly, proteins that normally interact with TDP-43 are not recruited to aggregates, while other factors linked to TDP-43 pathology, including Ataxin 2, specifically colocalize to inclusions and modify seeding-induced aggregation. Our findings indicate that TDP-43 aggregation, mislocalization and loss of function are strongly linked and suggest that disruption of TDP-43 autoregulation establishes a toxic feed-forward mechanism that amplifies aggregation and may be central in mediating this pathological connection.

DOI: https://doi.org/10.1101/2025.02.11.637743
Nat Commun. 2024 Dec 30. 15(1): 10829

Spatiotemporal proteomics reveals the biosynthetic lysosomal membrane protein interactome in neurons.

Chun Hei Li, Noortje Kersten, Nazmiye Özkan, Dan T M Nguyen, Max Koppers, Harm Post, Maarten Altelaar, Ginny G Farias.

Lysosomes are membrane-bound organelles critical for maintaining cellular homeostasis. Delivery of biosynthetic lysosomal proteins to lysosomes is crucial to orchestrate proper lysosomal function. However, it remains unknown how the delivery of biosynthetic lysosomal proteins to lysosomes is ensured in neurons, which are highly polarized cells. Here, we developed Protein Origin, Trafficking And Targeting to Organelle Mapping (POTATOMap), by combining trafficking synchronization and proximity-labelling based proteomics, to unravel the trafficking routes and interactome of the biosynthetic lysosomal membrane protein LAMP1 at specified time points. This approach, combined with advanced microscopy, enables us to identify the neuronal domain-specific trafficking machineries of biosynthetic LAMP1. We reveal a role in replenishing axonal lysosomes, in delivery of newly synthesized axonal synaptic proteins, and interactions with RNA granules to facilitate hitchhiking in the axon. POTATOMap offers a robust approach to map out dynamic biosynthetic protein trafficking and interactome from their origin to destination.

DOI: https://doi.org/10.1038/s41467-024-55052-w
bioRxiv. 2025 Feb 11. pii: 2024.11.13.623464. [Epub ahead of print]

Fructose-2,6-bisphosphate restores TDP-43 pathology-driven genome repair deficiency in motor neuron diseases.

Anirban Chakraborty, Joy Mitra, Vikas H Maloji Rao, Manohar Kodavati, Santi M Mandal, Satkarjeet K Gill, Sravan Gopalkrishnashetty Sreenivasmurthy, Velmarini Vasquez, Mikita Mankevich, Balaji Krishnan, Gourisankar Ghosh, Muralidhar L Hegde, Tapas Hazra.

TAR DNA-binding protein 43 (TDP-43) proteinopathy plays a critical role in neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal dementia (FTD). In our recent discovery, we identified that TDP-43 plays an essential role in DNA double-strand break (DSB) repair via the non-homologous end joining (NHEJ) pathway. Here, we found persistent DNA damage in the brains of ALS/FTD patients, primarily in the transcribed regions of the genome. We further investigated the underlying mechanism and found that polynucleotide kinase 3'-phosphatase (PNKP) activity was severely impaired in the nuclear extracts of both patient brains and TDP-43-depleted cells. PNKP is a key player in DSB repair within the transcribed genome, where its 3'-P termini processing activity is crucial for preventing persistent DNA damage and neuronal death. The inactivation of PNKP in ALS/FTD was due to reduced levels of its interacting partner, phosphofructo-2-kinase fructose 2,6 bisphosphatase (PFKFB3), and its biosynthetic product, fructose-2,6-bisphosphate (F2,6BP), an allosteric modulator of glycolysis. Recent work from our group has shown that F2,6BP acts as a positive modulator of PNKP activity in vivo . Notably, exogenous supplementation with F2,6BP restored PNKP activity in nuclear extracts from ALS/FTD brain samples and patient-derived induced pluripotent stem (iPS) cells harboring pathological mutations. Furthermore, we demonstrate that supplementation of F2,6BP restores genome integrity and partially rescues motor phenotype in a Drosophila model of ALS. Our findings underscore the possibility of exploring the therapeutic potential of F2,6BP or its analogs in TDP-43 pathology-associated motor neuron diseases.

DOI: https://doi.org/10.1101/2024.11.13.623464
Heliyon. 2025 Feb 15. 11(3): e42482

Metabolic rate and insulin-independent glucose uptake increase in a TDP-43Q331K mouse model of amyotrophic lateral sclerosis.

Tanya S McDonald, Cedric S Cui, Titaya Lerskiatiphanich, Jianina Marallag, John D Lee.

  Impaired glucose regulation is increasingly recognised in amyotrophic lateral sclerosis (ALS), yet the precise mechanisms remain unclear. Here, we investigated energy balance and glucose control in TAR DNA-binding protein 43 (TDP-43)Q331K mice, a model of ALS, at both the early and late symptomatic stages of disease. Mutant TDP-43Q331K mice and non-transgenic controls underwent indirect calorimetry, as well as intraperitoneal glucose, insulin, and glucagon tolerance testing. We also examined plasma hormone levels and quantified α- and β-cell areas in pancreatic islets. Throughout disease progression, TDP-43Q331K mice exhibited elevated metabolic rates, with a transient increase in food intake at the early stages. At the later stages of disease, heightened glucose uptake was observed despite unchanged insulin secretion or tolerance, indicating mechanisms independent of insulin. Notably, TDP-43Q331K mice maintained fasting blood glucose levels even when circulating glucagon levels were reduced, suggesting that alternative pathways contribute to preserving euglycemia. These findings reveal a distinct metabolic profile in TDP-43Q331K mice, underscoring the complexity of glucose dyshomeostasis in ALS.

Keywords:  Amyotrophic lateral sclerosis; Glucagon; Glucose tolerance; Insulin; Metabolic rate

DOI:  https://doi.org/10.1016/j.heliyon.2025.e42482
Neurobiol Dis. 2025 Feb 25. pii: S0969-9961(25)00072-5. [Epub ahead of print] 106856

Tsc1 deletion in Purkinje neurons disrupts the axon initial segment, impairing excitability and cerebellar function.

Samuel P Brown, Achintya K Jena, Joanna J Osko, Joseph L Ransdell.

  Loss-of-function mutations in tuberous sclerosis 1 (TSC1) are prevalent monogenic causes of autism spectrum disorder (ASD). Selective deletion of Tsc1 from mouse cerebellar Purkinje neurons has been shown to cause several ASD-linked behavioral impairments, which are linked to reduced Purkinje neuron repetitive firing rates. We used electrophysiology methods to investigate why Purkinje neuron-specific Tsc1 deletion (Tsc1mut/mut) impairs Purkinje neuron firing. These studies revealed a depolarized shift in action potential threshold voltage, an effect that we link to reduced expression of the fast-transient voltage-gated sodium (Nav) current in Tsc1mut/mut Purkinje neurons. The reduced Nav currents in these cells was associated with diminished secondary immunofluorescence from anti-pan Nav channel labeling at Purkinje neuron axon initial segments (AIS). Anti-ankyrinG immunofluorescence was also found to be significantly reduced at the AIS of Tsc1mut/mut Purkinje neurons, suggesting Tsc1 is necessary for the organization and functioning of the Purkinje neuron AIS. An analysis of the 1st and 2nd derivative of the action potential voltage-waveform supported this hypothesis, revealing spike initiation and propagation from the AIS of Tsc1mut/mut Purkinje neurons is impaired compared to age-matched control Purkinje neurons. Heterozygous Tsc1 deletion resulted in no significant changes in the firing properties of adult Purkinje neurons, and slight reductions in anti-pan Nav and anti-ankyrinG labeling at the Purkinje neuron AIS, revealing deficits in Purkinje neuron firing due to Tsc1 haploinsufficiency are delayed compared to age-matched Tsc1mut/mut Purkinje neurons. Together, these data reveal that the loss of Tsc1 impairs Purkinje neuron firing and membrane excitability through the dysregulation of proteins essential for AIS organization and function.

Keywords:  Purkinje neuron; Sodium channel; Tuberous sclerosis; ankyrinG; tsc1

DOI:  https://doi.org/10.1016/j.nbd.2025.106856
Front Neurosci. 2025 ;19 1533045

TDP-43 as a potential retinal biomarker for neurodegenerative diseases.

Margit Glashutter, Printha Wijesinghe, Joanne A Matsubara.

  TDP-43 proteinopathies are a spectrum of neurodegenerative diseases (NDDs) characterized by the pathological cytoplasmic aggregation of the TDP-43 protein. These include amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD), Alzheimer's disease (AD), chronic traumatic encephalopathy (CTE), and others. TDP-43 in the eye shows promise as a biomarker for these NDDs. Several studies have identified cytoplasmic TDP-43 inclusions in retinal layers of donors with ALS, FTLD, AD, CTE, and other conditions using immunohistochemistry. Our findings suggest that pathological aggregates of TDP-43 in the human retina are most prevalent in FTLD-TDP, ALS, and CTE, suggesting these diseases may provide the most reliable context for studying the potential of TDP-43 as a retinal biomarker. Animal model studies have been pivotal in exploring TDP-43's roles in the retina, including its nuclear and cytoplasmic localization, RNA binding properties, and interactions with other proteins. Despite these advances, more research is needed to develop therapeutic strategies. A major limitation of human autopsy studies is the lack of corresponding brain pathology assessments to confirm TDP-43 proteinopathy diagnosis and staging. Other limitations include small sample sizes, lack of antemortem eye pathology and clinical histories, and limited comparisons across multiple NDDs. Future directions for the TDP-43 as a retinal biomarker for NDDs include retinal tracers, hyperspectral imaging, oculomics, and machine learning development.

Keywords:  TDP-43 proteinopathy; biomarker; brain; eye; neurodegenerative disease; retina

DOI:  https://doi.org/10.3389/fnins.2025.1533045
Brain Sci. 2025 Jan 30. pii: 134. [Epub ahead of print]15(2):

Modeling ALS with Patient-Derived iPSCs: Recent Advances and Future Potentials.

Ladan Dawoody Nejad, Erik P Pioro.

  Amyotrophic lateral sclerosis (ALS) is a terminal complex neurodegenerative disease, with 10-15% of cases being familial and the majority being sporadic with no known cause. There are no animal models for the 85-90% of sporadic ALS cases. More creative, sophisticated models of ALS disease are required to unravel the mysteries of this complicated disease. While ALS patients urgently require new medications and treatments, suitable preclinical in vitro models for drug screening are lacking. Therefore, human-derived induced pluripotent stem cell (hiPSC) technology offers the opportunity to model diverse and unreachable cell types in a culture dish. In this review, we focus on recent hiPSC-derived ALS neuronal and non-neuronal models to examine the research progress of current ALS 2D monocultures, co-cultures, and more complex 3D-model organoids. Despite the challenges inherent to hiPSC-based models, their application to preclinical drug studies is enormous.

Keywords:  amyotrophic lateral sclerosis; astrocyte; co-culture; induced pluripotent stem cells; microglia; motor neuron; organoid; preclinical trials

DOI:  https://doi.org/10.3390/brainsci15020134
Biomater Sci. 2025 Feb 27.

An immunomodulatory encapsulation system to deliver human iPSC-derived dopaminergic neuron progenitors for Parkinson's disease treatment.

Emily A Atkinson, Holly N Gregory, Lara N Carter, Rachael E Evans, Victoria H Roberton, Rachael Dickman, James B Phillips.

Parkinson's disease is a neurodegenerative condition associated with the progressive loss of dopaminergic neurons. This leads to neurological impairments with heightening severity and is globally increasing in prevalence due to population ageing. Cell transplantation has demonstrated significant promise in altering the disease course in the clinic, and stem cell-derived grafts are being investigated. Current clinical protocols involve systemic immunosuppression to prevent graft rejection, which could potentially be avoided by encapsulating the therapeutic cells in a locally immunosuppressive biomaterial matrix before delivery. Here we report the progression of an immunomodulatory encapsulation system employing ultrapure alginate hydrogel beads alongside tacrolimus-loaded microparticles in the encapsulation of dopaminergic neuron progenitors derived from human induced pluripotent stem cells (hiPSCs). The hiPSC-derived progenitors were characterised and displayed robust viability after encapsulation within alginate beads, producing dopamine as they matured in vitro. The encapsulation system effectively reduced T cell activation (3-fold) and protected progenitors from cytotoxicity in vitro. The alginate bead diameter was optimised using microfluidics to yield spherical and monodisperse hydrogels with a median size of 215.6 ± 0.5 μm, suitable for delivery to the brain through a surgical cannula. This technology has the potential to advance cell transplantation by locally protecting grafts from the host immune system.

DOI: https://doi.org/10.1039/d4bm01566e
J Cell Biol. 2025 May 05. pii: e202410001. [Epub ahead of print]224(5):

TANGO2 is an acyl-CoA binding protein.

Agustin Leonardo Lujan, Ombretta Foresti, Jose Wojnacki, Gonzalo Bigliani, Nathalie Brouwers, Maria Jesus Pena, Stefania Androulaki, Tomomi Hashidate-Yoshida, Maria Kalyukina, Sergey S Novoselov, Hideo Shindou, Vivek Malhotra.

Loss of TANGO2 in humans precipitates metabolic crises during periods of heightened energy demand, such as fasting, infections, or high fever. TANGO2 has been implicated in various functions, including lipid metabolism and heme transport, and its cellular localization remains uncertain. In our study, we demonstrate that TANGO2 localizes to the mitochondrial lumen via a structural region containing LIL residues. Mutations in these LIL residues cause TANGO2 to relocate to the periphery of lipid droplets. We further show that purified TANGO2 binds acyl-coenzyme A, and mutations in the highly conserved NRDE sequence of TANGO2 inhibit this binding. Collectively, our findings suggest that TANGO2 serves as an acyl-coenzyme A binding protein. These insights may provide new avenues for addressing the severe cardiomyopathies and rhabdomyolysis associated with defective TANGO2 in humans.

DOI: https://doi.org/10.1083/jcb.202410001
J Cell Sci. 2025 Feb 15. pii: JCS263636. [Epub ahead of print]138(4):

TC10 on endosomes regulates the local balance between microtubule stability and dynamics through the PAK2-JNK pathway and promotes axon outgrowth.

Shingo Koinuma, Misa Miyaji, Suzuka Akiyama, Yasuyuki Ito, Hiroshi Takemura, Naoyuki Wada, Michihiro Igarashi, Takeshi Nakamura.

  The neuronal cytoskeleton comprises microtubules, actin filaments and neurofilaments, and plays a crucial role in axon outgrowth and transport. Microtubules and actin filaments have attracted considerable attention in axon regeneration studies. We have previously shown that TC10 (also known as RhoQ), a Rho family GTPase that promotes axon outgrowth through membrane addition, is required for efficient axon regeneration. This study demonstrates that TC10 on recycling endosomes, but not on the plasma membrane, balances microtubule stability and dynamics in the axons, thereby counteracting axon retraction. TC10 ablation reduced the phosphorylation of SCG10 (also known as STMN2) and MAP1B, which are neuronal microtubule-binding proteins and JNK substrates. Consistent with this, JNK phosphorylation was decreased in TC10-knockout neurons compared to in wild-type neurons. Furthermore, TC10 deletion significantly reduced PAK2 autophosphorylation. PAK2 was found on Rab11-positive endosomes in cell bodies and axons, and its localization to endosomes was reduced by TC10 loss. PAK inhibition reduced tubulin acetylation and JNK phosphorylation in axons. Furthermore, MKK4 and MKK7 (also known as MAP2K4 and MAP2K7, respectively) were found to mediate signaling from TC10-activated PAK to JNK on JIP1-positive endosomes. Overall, TC10 transmits a microtubule-regulatory signal from PAK2 to SCG10 and MAP1B via JNK on axonal endosomes.

Keywords:  Axon outgrowth; Endosome; JNK; Microtubule; PAK; Rho GTPase

DOI:  https://doi.org/10.1242/jcs.263636
Acta Neuropathol Commun. 2025 Feb 24. 13(1): 41

Hippocampal mitophagy alterations in MAPT-associated frontotemporal dementia with parkinsonism.

Tyrique Richardson, Xu Hou, Fabienne C Fiesel, Zbigniew K Wszolek, Dennis W Dickson, Wolfdieter Springer.

  The enzyme pair PINK1 and PRKN together orchestrates a cytoprotective mitophagy pathway that selectively tags damaged mitochondria with phospho-serine 65 ubiquitin (pS65-Ub) and directs them for autophagic-lysosomal degradation (mitophagy). We previously demonstrated a significant accumulation of pS65-Ub signals in autopsy brains of sporadic Lewy body disease and Alzheimer's disease cases, which strongly correlated with early tau pathology. In this study, we extended our analysis to a series of pathologically confirmed cases of frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17) harboring different pathogenic mutations in MAPT, the gene encoding tau. We assessed the morphology, levels, and distribution of the mitophagy tag pS65-Ub in several affected brain regions and hippocampal subregions of these cases. While tau pathological burden was similarly increased across all FTDP-17 cases, pS65-Ub immunopositive signals were strongly accumulated in P301L cases and only weakly present in N279K cases. In the hippocampus of both mutation groups, the density of pS65-Ub positive cells was overall the greatest in the dentate gyrus followed by the subiculum, CA1, and CA2/3, with the CA4 showing only minimal presence. Notably, positive cells in the subiculum carried greater numbers and particularly vacuolar pS65-Ub structures, while cells in the dentate gyrus mostly contained fewer and rather granular pS65-Ub inclusions. Single cell analyses revealed differential co-localization of pS65-Ub with mitochondria, autophagosomes, and lysosomes in these two regions. Together, our study demonstrates distinct mitophagy alteration in different FTDP-17 MAPT cases and hint at selective organelle failure in the hippocampal subregions that was associated with the P301L mutation.

Keywords:   MAPT P301L; Frontotemporal dementia with parkinsonism; Hippocampus; Mitochondria; Mitophagy; PINK1; PRKN; Parkin; Phosphorylated ubiquitin; Tau

DOI:  https://doi.org/10.1186/s40478-025-01955-8
Front Aging Neurosci. 2025 ;17 1522073

Optineurin overexpression ameliorates neurodegeneration through regulating neuroinflammation and mitochondrial quality in a murine model of amyotrophic lateral sclerosis.

Shumin Zhao, Ranran Chen, Yi An, Yali Zhang, Cheng Ma, Ying Gao, Yanchao Lu, Fei Yang, Xue Bai, Jingjing Zhang.

   Introduction: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the loss of motor neurons (MNs). Genetic mutations in Optineurin (OPTN) and Superoxide Dismutase 1 (SOD1) have been identified as causal factors for ALS. OPTN immunopositive inclusions have been confirmed in the cases of ALS with SOD1 mutations. However, the role of the OPTN gene in ALS caused by SOD1 mutations is ambiguous.
Methods: The murine Optn lentivirus and empty vector lentivirus were injected into SOD1 G93A mice after discovering variations in Optn expression over time. The phenotype onset date, life span, locomotor activity, and pathological changes in the spinal cord were determined and recorded subsequently. In addition, the influences on cellular apoptosis, mitochondrial dynamics, mitophagy, and neuroinflammation were further investigated.
Results: Optn expression was increased in the spinal cord of SOD1 G93A mice at the pre-symptomatic phase, but decreased after disease onset. Optn overexpression led to a 9.7% delay in the onset of disease and improved motor performance in SOD1 G93A mice. Optn overexpression also ameliorated the MNs loss by 46.8%. Moreover, all these ameliorating effects induced by Optn overexpression might be due to the inhibition of cellular apoptosis, improvement of mitochondrial quality, regulation of mitochondrial dynamics, promotion of mitophagy, and anti-inflammatory properties.
Conclusion: Our data demonstrate that Optn overexpression protects MNs, inhibites cellular apoptosis, improves mitochondrial quality and regulates neuroinflamation in SOD1 G93A mice at the pre-symptomatic stage.

Keywords:  amyotrophic lateral sclerosis; apoptosis; mitochondrial quality; neuroinflammation; optineurin

DOI:  https://doi.org/10.3389/fnagi.2025.1522073
Eur J Neurosci. 2025 Feb;61(4): e70030

Peripherin, A New Promising Biomarker in Neurological Disorders.

Carlo Manco, Delia Righi, Guido Primiano, Angela Romano, Marco Luigetti, Luca Leonardi, Nicola De Stefano, Domenico Plantone.

  Peripherin is a class III intermediate filament protein that has recently gained attention as a potential biomarker for axonal damage in the peripheral nervous system. This review examines peripherin gene expression, protein structure, and its functions in both healthy and diseased states. Peripherin is predominantly expressed in the peripheral nervous system, especially in motor and sensory neurons, and plays a critical role in neurite growth, stability, and axonal transport during myelination. Its expression is regulated by various cytokines and undergoes several post-transcriptional modifications. Peripherin interacts with multiple proteins, including neurofilaments and kinases, influencing cytoskeletal dynamics and neuronal functions. The review also explores peripherin involvement in several neurological disorders, such as Amyotrophic Lateral Sclerosis, where its abnormal expression and aggregation contribute to disease pathology. Additionally, peripherin has been linked to polyneuropathies, traumatic axonal injury, and diabetic neuropathy, suggesting its broader relevance as a biomarker in these conditions. The potential of peripherin as a biomarker is further supported by recent studies using ultrasensitive detection methods, which have identified elevated peripherin levels in the serum of patients with neurological diseases. Despite the promising findings, the application of peripherin as a biomarker in clinical settings remains limited, primarily due to challenges in its detection and the need for further validation in diverse patient populations. Future research directions include the development of more sensitive assays and the exploration of peripherin's role in non-neuronal tissues, which may expand its diagnostic and therapeutic potential.

Keywords:  Peripherin; amyotrophic lateral sclerosis; biomarker; neurofilaments; polyneuropathy

DOI:  https://doi.org/10.1111/ejn.70030
J Neurol. 2025 Feb 26. 272(3): 233

Advancements in genetic research and RNA therapy strategies for amyotrophic lateral sclerosis (ALS): current progress and future prospects.

Paola Ruffo, Bryan J Traynor, Francesca Luisa Conforti.

  This review explores the intricate landscape of neurodegenerative disease research, focusing on Amyotrophic Lateral Sclerosis (ALS) and the intersection of genetics and RNA biology to investigate the causative pathogenetic basis of this fatal disease. ALS is a severe neurodegenerative disease characterized by the progressive loss of motor neurons, leading to muscle weakness and paralysis. Despite significant research advances, the exact cause of ALS remains largely unknown. Thanks to the application of next-generation sequencing (NGS) approaches, it was possible to highlight the fundamental role of rare variants with large effect sizes and involvement of portions of non-coding RNA, providing valuable information on risk prediction, diagnosis, and treatment of age-related diseases, such as ALS. Genetic research has provided valuable insights into the pathophysiology of ALS, leading to the development of targeted therapies such as antisense oligonucleotides (ASOs). Regulatory agencies in several countries are evaluating the commercialization of Qalsody (Tofersen) for SOD1-associated ALS, highlighting the potential of gene-targeted therapies. Furthermore, the emerging significance of microRNAs (miRNAs) and long RNAs are of great interest. MiRNAs have emerged as promising biomarkers for diagnosing ALS and monitoring disease progression. Understanding the role of lncRNAs in the pathogenesis of ALS opens new avenues for therapeutic intervention. However, challenges remain in delivering RNA-based therapeutics to the central nervous system. Advances in genetic screening and personalized medicine hold promise for improving the management of ALS. Ongoing clinical trials use genomic approaches for patient stratification and drug targeting. Further research into the role of non-coding RNAs in the pathogenesis of ALS and their potential as therapeutic targets is crucial to the development of effective treatments for this devastating disease.

Keywords:  Amyotrophic lateral sclerosis; Gene-targeted therapies; Next-generation sequencing; Non-coding RNA

DOI:  https://doi.org/10.1007/s00415-025-12975-8
Proc Natl Acad Sci U S A. 2025 Mar 04. 122(9): e2411811122

Disruption of G3BP1 granules promotes mammalian CNS and PNS axon regeneration.

Pabitra K Sahoo, Manasi Agrawal, Nicholas Hanovice, Patricia J Ward, Meghal Desai, Terika P Smith, HaoMin SiMa, Jennifer N Dulin, Lauren S Vaughn, Mark H Tuszynski, Kristy Welshhans, Larry I Benowitz, Arthur W English, John D Houle, Jeffery L Twiss.

  Depletion or inhibition of core stress granule proteins, G3BP1 in mammals and TIAR-2 in Caenorhabditis elegans, increases the growth of spontaneously regenerating axons. Inhibition of G3BP1 by expression of its acidic or "B-domain" accelerates axon regeneration after nerve injury, bringing a potential therapeutic strategy for peripheral nerve repair. Here, we asked whether G3BP1 inhibition is a viable strategy to promote regeneration in injured mammalian central nervous system (CNS) where axons do not regenerate spontaneously. G3BP1 B-domain expression was found to promote axon regeneration in the transected spinal cord provided with a permissive peripheral nerve graft (PNG) as well as in crushed optic nerve. Moreover, a cell-permeable peptide (CPP) to a subregion of B-domain (rodent G3BP1 amino acids 190 to 208) accelerated axon regeneration after peripheral nerve injury and promoted regrowth of reticulospinal axons into the distal transected spinal cord through a bridging PNG. G3BP1 CPP promoted axon growth from rodent and human neurons cultured on permissive substrates, and this function required alternating Glu/Asp-Pro repeats that impart a unique predicted tertiary structure. The G3BP1 CPP disassembles axonal G3BP1, G3BP2, and FMRP, but not FXR1, granules and selectively increases axonal protein synthesis in cortical neurons. These studies identify G3BP1 granules as a key regulator of axon growth in CNS neurons and demonstrate that disassembly of these granules promotes retinal axon regeneration in injured optic nerve and reticulospinal axon elongation into permissive environments after CNS injury. This work highlights G3BP1 granule disassembly as a potential therapeutic strategy for enhancing axon growth and neural repair.

Keywords:  CNS injury; G3BP1; axon regeneration; local protein synthesis; stress granules

DOI:  https://doi.org/10.1073/pnas.2411811122
Autophagy. 2025 Feb 27.

Mitochondrial dynamics and quality control regulate proteostasis in neuronal ischemia-reperfusion.

Garrett M Fogo, Sarita Raghunayakula, Katlynn J Emaus, Francisco J Torres Torres, Gary Shangguan, Joseph M Wider, Maik Hüttemann, Thomas H Sanderson.

  Mitochondrial damage and dysfunction are hallmarks of neuronal injury during cerebral ischemia-reperfusion (I/R). Critical mitochondrial functions including energy production and cell signaling are perturbed during I/R, often exacerbating damage and contributing to secondary injury. The integrity of the mitochondrial proteome is essential for efficient function. Mitochondrial proteostasis is mediated by the cooperative forces of mitophagy and intramitochondrial proteolysis. The aim of this study was to elucidate the patterns of mitochondrial protein dynamics and their key regulators during an in vitro model of neuronal I/R injury. Utilizing the MitoTimer reporter, we quantified mitochondrial protein oxidation and turnover during I/R injury, highlighting a key point at 2 h reoxygenation for aged/oxidized protein turnover. This turnover was found to be mediated by both LONP1-dependent proteolysis and PRKN/parkin-dependent mitophagy. Additionally, the proteostatic response of neuronal mitochondria is influenced by both mitochondrial fusion and fission machinery. Our findings highlight the involvement of both mitophagy and intramitochondrial proteolysis in the response to I/R injury.

Keywords:  Fission; LONP1; PRKN; fusion; mitophagy; neuron

DOI:  https://doi.org/10.1080/15548627.2025.2472586
Alzheimers Dement. 2025 Feb 28. e14403

The tau isoform 1N4R confers vulnerability of MAPT knockout human iPSC-derived neurons to amyloid beta and phosphorylated tau-induced neuronal dysfunction.

Sarah Buchholz, Mohamed Aghyad Al Kabbani, Michael Bell-Simons, Lena Kluge, Cagla Cagmak, Jennifer Klimek, Natja Haag, Lukas C Iohan, Audrey Coulon, Marcos R Costa, Devrim Kilinc, Hans Zempel.

   INTRODUCTION: Human tau protein, composed of six brain-specific isoforms, is a major driver of Alzheimer's disease (AD). The role of its isoforms however remains unclear and human AD models are scarce.
METHODS: We generated human MAPT- (tau-) knockout (KO) induced pluripotent stem cells (iPSC) using CRISPR/Cas9, differentiated these into glutamatergic neurons, and assessed isoform-specific functions of tau in these neurons. We used omic- approaches, live-cell imaging, subcompartmental analysis, and lentivirus-based reintroduction of specific tau isoforms to investigate isoform-mediated neuronal dysfunction in an AD model.
RESULTS: Tau KO human iPSC-derived neurons showed decreased neurite outgrowth and axon initial segment length and, notably, resisted amyloid beta oligomer (AβO)-induced neuronal activity reduction. Introducing the 1N4R-tau isoform, but not other isoforms, confers AβO vulnerability and increases KxGS phosphorylation of tau, without altering neuronal activity or microtubule modifications.
DISCUSSION: While tau KO impacts neuronal development and activity, tau-KO also confers resistance against AβO insult. 1N4R-tau likely mediates AβO-induced and phosphorylated tau toxicity, representing a novel prime therapeutic target for AD.
HIGHLIGHTS: Tau knockout alters neurite growth and axon initial segment formation in human neurons. Tau isoforms show differential axonal localization in human neurons. Tau depletion protects against amyloid beta oligomer (AβO)-mediated neurotoxicity. 1N4R tau mediates AβO-induced toxicity in human neurons.

Keywords:  Alzheimer's disease; amyloid beta; axon initial segment; human induced pluripotent stem cells; induced neurons; isoforms; knockout; neuronal activity; tau; tauopathy

DOI:  https://doi.org/10.1002/alz.14403
Neuroinformatics. 2025 Feb 25. 23(2): 22

Overcoming Neuroanatomical Mapping and Computational Barriers in Human Brain Synaptic Architecture.

Rahul Kumar, Ethan Waisberg, Joshua Ong, Phani Paladugu, Dylan Amiri, Ram Jagadeesan.

  In this Matters Arising, we critically examine the data processing and computational challenges highlighted under the high-resolution, three-dimensional reconstruction of human cortical tissue by Shapson-Coe et al. While the study represents a technical milestone in connectomics, involving a 1.4-petabyte dataset derived from mapping a cubic millimeter of temporal cortex, the findings also reveal the substantial obstacles inherent in scaling such approaches to the entire human brain. Beyond the application of artificial intelligence (AI) for segmentation and synapse detection, the study underscores the immense complexity of data acquisition, cleaning, alignment, and visualization at this scale. This article contextualizes these challenges by comparing the computational and infrastructural requirements of the Shapson-Coe work to other large-scale neuroscience initiatives, such as the fruit fly brain atlas, and explores emerging technologies like quantum computing and neuromorphic hardware as potential solutions. Additionally, we discuss the ethical and logistical implications of managing zettabyte-scale datasets and emphasize the necessity of international collaboration to achieve the ambitious goal of mapping the human connectome. By critically addressing these challenges and potential solutions, this article aims to guide future advancements in the field of connectomics and their transformative applications in neuroscience, artificial intelligence, and medicine.

Keywords:  Artificial intelligence; Brain networks; Machine learning; Neuroimaging; Neuroscience

DOI:  https://doi.org/10.1007/s12021-025-09715-8
Cells. 2025 Feb 14. pii: 282. [Epub ahead of print]14(4):

Autophagy in Tissue Repair and Regeneration.

Daniel Moreno-Blas, Teresa Adell, Cristina González-Estévez.

  Autophagy is a cellular recycling system that, through the sequestration and degradation of intracellular components regulates multiple cellular functions to maintain cellular homeostasis and survival. Dysregulation of autophagy is closely associated with the development of physiological alterations and human diseases, including the loss of regenerative capacity. Tissue regeneration is a highly complex process that relies on the coordinated interplay of several cellular processes, such as injury sensing, defense responses, cell proliferation, differentiation, migration, and cellular senescence. These processes act synergistically to repair or replace damaged tissues and restore their morphology and function. In this review, we examine the evidence supporting the involvement of the autophagy pathway in the different cellular mechanisms comprising the processes of regeneration and repair across different regenerative contexts. Additionally, we explore how modulating autophagy can enhance or accelerate regeneration and repair, highlighting autophagy as a promising therapeutic target in regenerative medicine for the development of autophagy-based treatments for human diseases.

Keywords:  autophagy; injury; planarian; regeneration; senescence; stem cell; tissue repair

DOI:  https://doi.org/10.3390/cells14040282
Int J Mol Sci. 2025 Feb 12. pii: 1539. [Epub ahead of print]26(4):

Human iPSC-Derived Muscle Cells as a New Model for Investigation of EDMD1 Pathogenesis.

Marta Lisowska, Marta Rowińska, Aleksandra Suszyńska, Claudia Bearzi, Izabela Łaczmańska, Julia Hanusek, Amanda Kunik, Volha Dzianisava, Ryszard Rzepecki, Magdalena Machowska, Katarzyna Piekarowicz.

  Emery-Dreifuss muscular dystrophy type 1 (EDMD1) is a rare genetic disease caused by mutations in the EMD gene, which encodes the nuclear envelope protein emerin. Despite understanding the genetic basis of the disease, the molecular mechanism underlying muscle and cardiac pathogenesis remains elusive. Progress is restricted by the limited availability of patient-derived samples; therefore, there is an urgent need for human-specific cellular models. In this study, we present the generation and characterization of induced pluripotent stem cell (iPSC) lines derived from EDMD1 patients carrying EMD mutations that lead to truncated or absent emerin, together with iPSCs from healthy donor. The patient-specific iPSCs exhibit stable karyotypes, maintain appropriate morphology, express pluripotency markers, and demonstrate the ability to differentiate into three germ layers. To model EDMD1, these iPSCs were differentiated into myogenic progenitors, myoblasts, and multinucleated myotubes, which represent all stages of myogenesis. Each developmental stage was validated by the presence of stage-specific markers, ensuring the accuracy of the model. We present the first iPSC-based in vitro platform that captures the complexity of EDMD1 pathogenesis during myogenesis. This model can significantly contribute to understanding disease mechanisms and develop the targeted therapeutic strategies for EDMD1.

Keywords:  EMD mutation; Emery–Dreifuss muscular dystrophy; disease modeling; emerin; muscle differentiation in vitro; skeletal muscles; stem cells

DOI:  https://doi.org/10.3390/ijms26041539
Autophagy Rep. 2024 ;pii: 2434379. [Epub ahead of print]3(1):

Alterations of PINK1-PRKN signaling in mice during normal aging.

Zahra Baninameh, Jens O Watzlawik, Xu Hou, Tyrique Richardson, Nicholas W Kurchaba, Tingxiang Yan, Damian N Di Florio, DeLisa Fairweather, Lu Kang, Justin H Nguyen, Takahisa Kanekiyo, Dennis W Dickson, Sachiko Noda, Shigeto Sato, Nobutaka Hattori, Matthew S Goldberg, Ian G Ganley, Kelly L Stauch, Fabienne C Fiesel, Wolfdieter Springer.

  The ubiquitin kinase-ligase pair PINK1-PRKN identifies and selectively marks damaged mitochondria for elimination via the autophagy-lysosome system (mitophagy). While this cytoprotective pathway has been extensively studied in vitro upon acute and complete depolarization of mitochondria, the significance of PINK1-PRKN mitophagy in vivo is less well established. Here we used a novel approach to study PINK1-PRKN signaling in different energetically demanding tissues of mice during normal aging. We demonstrate a generally increased expression of both genes and enhanced enzymatic activity with aging across tissue types. Collectively our data suggest a distinct regulation of PINK1-PRKN signaling under basal conditions with the most pronounced activation and flux of the pathway in mouse heart compared to brain or skeletal muscle. Our biochemical analyses complement existing mitophagy reporter readouts and provide an important baseline assessment in vivo, setting the stage for further investigations of the PINK1-PRKN pathway during stress and in relevant disease conditions.

Keywords:  PINK1; PRKN; aging; brain; heart; mice; mitochondria; mitophagy; phosphorylated ubiquitin; skeletal muscle

DOI:  https://doi.org/10.1080/27694127.2024.2434379
Mol Ther Methods Clin Dev. 2025 Mar 13. 33(1): 101415

Human striatal progenitor cells that contain inducible safeguards and overexpress BDNF rescue Huntington's disease phenotypes.

Danielle A Simmons, Sridhar Selvaraj, Tingshuo Chen, Gloria Cao, Talita Souto Camelo, Tyne L M McHugh, Selena Gonzalez, Renata M Martin, Juste Simanauskaite, Nobuko Uchida, Matthew H Porteus, Frank M Longo.

  Huntington's disease (HD) is an autosomal-dominant neurodegenerative disorder characterized by striatal atrophy. Reduced trophic support due to decreased striatal levels of neurotrophins (NTs), mainly brain-derived neurotrophic factor (BDNF), contributes importantly to HD pathogenesis; restoring NTs has significant therapeutic potential. Human pluripotent stem cells (hPSCs) offer a scalable platform for NT delivery but have potential safety risks including teratoma formation. We engineered hPSCs to constitutively produce BDNF and contain inducible safeguards to eliminate these cells if safety concerns arise. This study examined the efficacy of intrastriatally transplanted striatal progenitor cells (STRpcs) derived from these hPSCs against HD phenotypes in R6/2 mice. Engrafted STRpcs overexpressing BDNF alleviated motor and cognitive deficits and reduced mutant huntingtin aggregates. Activating the inducible safety switch with rapamycin safely eliminated the engrafted cells. These results demonstrate that BDNF delivery via a novel hPSC-based platform incorporating safety switches could be a safe and effective HD therapeutic.

Keywords:  Huntington’s disease; brain-derived neurotrophic factor; human pluripotent stem cells; neurotrophin; striatal progenitors

DOI:  https://doi.org/10.1016/j.omtm.2025.101415
Microsc Microanal. 2025 Feb 17. pii: ozae119. [Epub ahead of print]31(1):

Structural Analysis of Cerebral Organoids Using Confocal Microscopy and Transmission/Scanning Electron Microscopy.

Seulgi Noh, Yurim Park, Beomsue Kim, Ji Young Mun.

  Cerebral organoid cultures from human-induced pluripotent stem cells are widely used to study complex human brain development; however, there is still limited ultrastructural information regarding the development. In this study, we examined the structural details of cerebral organoids using various microscopy techniques. Two protocols were chosen as representative methods for the development of brain organoids: the classic whole-cerebral organoid (Whole-CO) culture technique, and the air-liquid interface-cerebral organoid (ALI-CO) culture technique. Immunostained confocal laser scanning microscopy (CLSM) revealed the formation of the CTIP2- and TBR1-positive cortical deep layer on days 90 and 150, depending on the developmental progress of both methods. Furthermore, the presence of astrocytes and oligodendrocytes was verified through immunostained CLSM utilizing two-dimensional and three-dimensional reconstruction images after a 150-day period. Transmission electron microscopy analysis revealed nanometer-resolution details of the cellular organelles and neuron-specific structures including synapses and myelin. Large-area scanning electron microscopy confirmed the well-developed neuronal connectivity from each culture method on day 150. Using those microscopy techniques, we clearly showed significant details within two representative culture protocols, the Whole-CO and ALI-CO culture methods. These multi-level images provide ultrastructural insight into the features of cerebral organoids depending on the developmental stage.

Keywords:  air–liquid interface; cerebral organoid; large-area scanning electron microscopy; transmission electron microscopy; ultrastructure

DOI:  https://doi.org/10.1093/mam/ozae119
Antioxidants (Basel). 2025 Jan 22. pii: 125. [Epub ahead of print]14(2):

Lysosome-Mitochondrial Crosstalk in Cellular Stress and Disease.

Szilvia Kiraly, Jack Stanley, Emily R Eden.

  The perception of lysosomes and mitochondria as entirely separate and independent entities that degrade material and produce ATP, respectively, has been challenged in recent years as not only more complex roles for both organelles, but also an unanticipated level of interdependence are being uncovered. Coupled lysosome and mitochondrial function and dysfunction involve complex crosstalk between the two organelles which goes beyond mitochondrial quality control and lysosome-mediated clearance of damaged mitochondria through mitophagy. Our understanding of crosstalk between these two essential metabolic organelles has been transformed by major advances in the field of membrane contact sites biology. We now know that membrane contact sites between lysosomes and mitochondria play central roles in inter-organelle communication. This importance of mitochondria-lysosome contacts (MLCs) in cellular homeostasis, evinced by the growing number of diseases that have been associated with their dysregulation, is starting to be appreciated. How MLCs are regulated and how their coordination with other pathways of lysosome-mitochondria crosstalk is achieved are the subjects of ongoing scrutiny, but this review explores the current understanding of the complex crosstalk governing the function of the two organelles and its impact on cellular stress and disease.

Keywords:  crosstalk; lysosomes; membrane contact sites; mitochondria

DOI:  https://doi.org/10.3390/antiox14020125
bioRxiv. 2025 Feb 12. pii: 2025.02.11.637689. [Epub ahead of print]

Axonal Mechanotransduction Drives Cytoskeletal Responses to Physiological Mechanical Forces.

Grace L Swaim, Oliver V Glomb, Yi Xie, Chloe Emerson, Zhuoyuan Li, Daniel Beaudet, Adam G Hendricks, Shaul Yogev.

Axons experience strong mechanical forces due to animal movement. While these forces serve as sensory cues in mechanosensory neurons, their impact on other neuron types remains poorly defined. Here, we uncover signaling that controls an axonal cytoskeletal response to external physiological forces and plays a key role in axonal integrity. Live imaging of microtubules at single-polymer resolution in a C. elegans motor neuron reveals local oscillatory movements that fine-tune polymer positioning. Combining cell-specific chemogenetic silencing with targeted degradation alleles to distinguish neuron-intrinsic from extrinsic regulators of these movements, we find that they are driven by muscle contractions and require the mechanosensitive protein Talin, the small GTPase RhoA, and actomyosin activity in the axon. Genetic perturbation of the axon's ability to buffer tension by disrupting the spectrin-based membrane-associated skeleton leads to RhoA hyperactivation, actomyosin relocalization to foci at microtubule ends, and converts local oscillations into processive bidirectional movements. This results in large gaps between microtubules, disrupting coverage of the axon and leading to its breakage and degeneration. Notably, hyperpolarizing muscle or degrading components of the mechanotransduction signaling pathway in the axon rescues cytoskeletal defects in spectrin-deficient axons. These results identify mechanisms of an axonal cytoskeletal response to physiological forces and highlight the importance of force-buffering and mechanotransduction signaling for axonal integrity.

DOI: https://doi.org/10.1101/2025.02.11.637689
EMBO Rep. 2025 Feb 27.

The spectrum of lysosomal stress and damage responses: from mechanosensing to inflammation.

Ori Scott, Ekambir Saran, Spencer A Freeman.

  Cells and tissues turn over their aged and damaged components in order to adapt to a changing environment and maintain homeostasis. These functions rely on lysosomes, dynamic and heterogeneous organelles that play essential roles in nutrient redistribution, metabolism, signaling, gene regulation, plasma membrane repair, and immunity. Because of metabolic fluctuations and pathogenic threats, lysosomes must adapt in the short and long term to maintain functionality. In response to such challenges, lysosomes deploy a variety of mechanisms that prevent the breaching of their membrane and escape of their contents, including pathogen-associated molecules and hydrolases. While transient permeabilization of the lysosomal membrane can have acute beneficial effects, supporting inflammation and antigen cross-presentation, sustained or repeated lysosomal perforations have adverse metabolic and transcriptional consequences and can lead to cell death. This review outlines factors contributing to lysosomal stress and damage perception, as well as remedial processes aimed at addressing lysosomal disruptions. We conclude that lysosomal stress plays widespread roles in human physiology and pathology, the understanding and manipulation of which can open the door to novel therapeutic strategies.

Keywords:  Autophagy; Glycocalyx; Host–pathogen; Phagosolysosome; Pore-forming Toxins

DOI:  https://doi.org/10.1038/s44319-025-00405-9
J Physiol. 2025 Feb 22.

Optic nerve injury impairs intrinsic mechanisms underlying electrical activity in a resilient retinal ganglion cell.

Thomas E Zapadka, Nicholas M Tran, Jonathan B Demb.

  Retinal ganglion cells (RGCs) are the sole output neurons of the retina and convey visual information to the brain via their axons in the optic nerve. Following injury to the optic nerve, RGC axons degenerate and many cells die. For example, a model of axon injury, the optic nerve crush (ONC), kills ∼80% of RGCs after 2 weeks. Surviving cells are biased towards 'resilient' types, including several with sustained firing to light stimulation. RGC survival may depend on activity, and there is limited understanding of how or why activity changes following optic nerve injury. Here we quantified the electrophysiological properties of a highly resilient RGC type, the sustained ON-Alpha (AlphaONS) RGC, 7 days after ONC with extracellular and whole-cell patch clamp recording. Both light- and current-driven firing were reduced after ONC, but synaptic inputs were largely intact. Resting membrane potential and input resistance were relatively unchanged, while voltage-gated currents were impaired, including a reduction in voltage-gated sodium channel current and channel density in the axon initial segment. Hyperpolarization or chelation of intracellular calcium partially rescued firing rates. Extracellular recordings at 3 days following ONC showed normal light-evoked firing from AlphaONS RGCs and other Alpha RGCs, including susceptible types. These data suggest that an injured resilient RGC reduces its activity by 1 week after injury as a consequence of reduced voltage-gated current and downregulation of intrinsic excitability via a Ca2+-dependent mechanism. Reduced excitability may be due to degradation of the axon but could also be energetically beneficial, preserving energy for survival and regeneration. KEY POINTS: Retinal ganglion cell (RGC) types show diverse rates of survival after axon injury. A resilient RGC type (sustained ON-Alpha RGC) maintains its synaptic inputs 1 week after injury. The resilient RGC type shows diminished firing and reduced expression of axon initial segment genes 1 week after injury Activity deficits reflect dysfunction of intrinsic properties (Na+ channels, intracellular Ca2+), not changes to synaptic input. Both resilient and susceptible Alpha RGC types show intact firing at 3 days after injury, suggesting that activity at this time point does not predict resilience.

Keywords:  action potential; neurodegeneration; optic nerve crush; retinal ganglion cell; sodium channel; synapse

DOI:  https://doi.org/10.1113/JP286414
Nat Rev Drug Discov. 2025 Feb 24.

Reversing lysosomal dysfunction to treat PAH.

Sarah Crunkhorn.

DOI: https://doi.org/10.1038/d41573-025-00035-9
Neuron. 2025 Feb 15. pii: S0896-6273(25)00045-5. [Epub ahead of print]

Neuronal autophagy in the control of synapse function.

Anna Karpova, P Robin Hiesinger, Marijn Kuijpers, Anne Albrecht, Janine Kirstein, Maria Andres-Alonso, Alexander Biermeier, Britta J Eickholt, Marina Mikhaylova, Marta Maglione, Carolina Montenegro-Venegas, Stephan J Sigrist, Eckart D Gundelfinger, Volker Haucke, Michael R Kreutz.

  Neurons are long-lived postmitotic cells that capitalize on autophagy to remove toxic or defective proteins and organelles to maintain neurotransmission and the integrity of their functional proteome. Mutations in autophagy genes cause congenital diseases, sharing prominent brain dysfunctions including epilepsy, intellectual disability, and neurodegeneration. Ablation of core autophagy genes in neurons or glia disrupts normal behavior, leading to motor deficits, memory impairment, altered sociability, and epilepsy, which are associated with defects in synapse maturation, plasticity, and neurotransmitter release. In spite of the importance of autophagy for brain physiology, the substrates of neuronal autophagy and the mechanisms by which defects in autophagy affect synaptic function in health and disease remain controversial. Here, we summarize the current state of knowledge on neuronal autophagy, address the existing controversies and inconsistencies in the field, and provide a roadmap for future research on the role of autophagy in the control of synaptic function.

Keywords:  autophagy; memory; neurological diseases; neurotransmission; synapse; synaptic plasticity

DOI:  https://doi.org/10.1016/j.neuron.2025.01.019