bims-axbals 2025-06-08 papers

bims-axbals

Biomed News

on Axonal biology and ALS

Issue of 2025–06–08
thirty-two papers selected by
TJ Krzystek

β-propeller protein-associated neurodegeneration protein WDR45 regulates stress granule disassembly via phase separation with Caprin-1.
IsomiR Utility in ALS Prognostication.
RNA-binding proteins in ALS and FTD: from pathogenic mechanisms to therapeutic insights.
Navigating the neuronal recycling bin: Another look at huntingtin in coordinating autophagy.
TDP-43 dysregulation of polyadenylation site selection is a defining feature of RNA misprocessing in amyotrophic lateral sclerosis and frontotemporal dementia.
Analysis of the splicing landscape of the frontal cortex in FTLD-TDP reveals subtype specific patterns and cryptic splicing.
Automated high-throughput patch clamp electrophysiology of hiPSC-derived neuronal models.
Vimentin network dysregulation mediates neurite deficits in SNCA duplication Parkinson's patient-derived midbrain neurons.
Astrocyte induction of disease-associated microglia is suppressed by acute exposure to fAD neurons in human iPSC triple cultures.
SARM1 activation induces reversible mitochondrial dysfunction and can be prevented in human neurons by antisense oligonucleotides.
[Study on mechanism of naringin in alleviating cerebral ischemia/reperfusion injury based on DRP1/LRRK2/MCU axis].
Synaptotoxic effects of extracellular tau are mediated by its microtubule-binding region.
CacyBP/SIP Protein Regulates the Length and Branching of Neuronal Processes During Cortical Development.
ATG9A and ARFIP2 cooperate to control PI4P levels for lysosomal repair.
Generation of iPSC lines with tagged α-synuclein for visualization of endogenous protein in human cellular models of neurodegenerative disorders.
Synchrotron radiation FTIR microspectroscopy enables measuring dynamic cell identity patterning during human 3D differentiation.
Regulation of Axonal Microtubule Polarity Orientation in Different Kinds of Neurons.
Clearance of protein aggregates during cell division.
Stem cell therapy for Parkinson's disease: A new hope for neural regeneration.
har-1/CHCHD10 mutations induce neurodegeneration and mitochondrial fragmentation in Caenorhabditis elegans.
Comprehensive characterization and validation of the Prp-hPFN1G118V mouse model: Guidelines for preclinical therapeutic testing for ALS.
Myristoylation of TMEM106B by NMT1/2 regulates TMEM106B trafficking and turnover.
Progression of differentiation of iPSCs into specific subtypes of neurons.
Differentiation of SH-SY5Y Cells into Cortical Neuron-like Cells for Tauopathy Modeling and Seeding Assays.
Processivity and BDNF-dependent modulation of signalling endosome axonal transport are impaired in mice with advanced age.
Wet scissors: How biomolecular condensates cut cellular membranes.
Inflammation-induced lysosomal dysfunction in human iPSC-derived microglia is exacerbated by APOE 4/4 genotype.
Dissociation of the mTOR protein interaction network following neuronal activation is altered by Shank3 mutation.
Down-regulation of neuroprotective protein kinase D in Huntington´s disease.
HOPS-dependent vesicle tethering lock inhibits endolysosomal fusions and autophagosome secretion upon the loss of Syntaxin17.
RAS/ERK signaling and PLK1: Coordinating developmental regulation and disease mechanisms.
Characterization of extracellular vesicles and miRNA released by cerebral organoids.

Nat Commun. 2025 Jun 05. 16(1): 5227

β-propeller protein-associated neurodegeneration protein WDR45 regulates stress granule disassembly via phase separation with Caprin-1.

Yin Li, Jie Fang, Yuqi Ding, Xilong Zhang, Ying Liu, Wanting Qiu, He Xu, Yunzhe Kang, Jiayu Chen, Yanyan Gao, Yan G Zhao, Peiguo Yang, Bo Wang, Wenmin Tian, Yang Chen, Wenjian Bi, Peipei Zhang.

β-propeller protein-associated neurodegeneration (BPAN) is a rare X-linked neurodegenerative disorder caused by mutations in the WDR45 gene, yet its molecular mechanisms remain poorly understood. Here, we identify a role for WDR45 in stress granule (SG) disassembly, mediated through its phase separation with Caprin-1. We demonstrate that WDR45 forms gel-like condensates via its WD5 domain, which competitively displaces G3BP1 from Caprin-1 to promote SG disassembly. BPAN-associated WDR45 mutations impair condensate formation and Caprin-1 interaction, leading to delayed SG disassembly, which correlates with earlier disease onset. WDR45 depletion also exacerbates amyotrophic lateral sclerosis-associated pathological SGs, highlighting its broader relevance to neurodegenerative diseases. Using iPSC-derived midbrain neurons from a BPAN patient, we demonstrate delayed SG recovery, directly linking WDR45 dysfunction to neurodegeneration. These findings establish WDR45 as a critical regulator of SG dynamics, uncover a potential molecular basis of BPAN pathogenesis, and identify therapeutic targets for neurodegenerative diseases associated with SG dysregulation.

DOI: https://doi.org/10.1038/s41467-025-60583-x
medRxiv. 2025 May 14. pii: 2025.05.12.25325848. [Epub ahead of print]

IsomiR Utility in ALS Prognostication.

Y Cohen, I Sinai, I Magen, M Y Danino, J Wuu, A Malaspina, M Benatar, E Hornstein.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive motor neuron loss. IsomiRs are microRNA isoforms that arise from alternative processing or editing events during miRNA biogenesis. While isomiRs may carry distinct biological and clinical relevance, their potential as cell-free biomarkers in neurodegeneration remains largely unexplored. Intriguingly, loss of TAR DNA-binding protein 43 (TDP-43) nuclear function is a hallmark of disease and is known to impair isomiR expression. Here, we investigated the prognostic utility of plasma isomiRs in ALS, using next-generation sequencing. We profiled cell-free isomiRs in 154 ALS patients from a British cohort and identified higher levels of one isomiR, let-7g-5p.t, to be associated with longer survival. This finding was independently validated in an international ALS cohort of 200 patients and was in two orthogonal approaches. let-7g-5p.t prognostic utility was comparable to that of neurofilament light chain (NfL) or miR-181. These results establish isomiRs as a novel class of blood-based biomarkers in ALS with potential to refine prognostication in clinical trials for neurodegenerative diseases.

DOI: https://doi.org/10.1101/2025.05.12.25325848
Mol Neurodegener. 2025 Jun 04. 20(1): 64

RNA-binding proteins in ALS and FTD: from pathogenic mechanisms to therapeutic insights.

Jens Rummens, Sandrine Da Cruz.

  Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are devastating neurodegenerative disorders with overlapping clinical, genetic and pathological features. A large body of evidence highlights the critical role of RNA-binding proteins (RBPs) - in particular TAR DNA-binding protein 43 (TDP-43) and Fused in sarcoma (FUS) - in the pathogenesis of these diseases. These RBPs normally regulate various key aspects of RNA metabolism in the nervous system (by assembling into transient biomolecular condensates), but undergo cytoplasmic mislocalization and pathological aggregation in ALS and FTD. Furthermore, emerging evidence suggests that RBP-containing aggregates may propagate through the nervous system in a prion-like manner, driving the progression of these neurodegenerative diseases. In this review, we summarize the genetic and neuropathological findings that establish RBP dysfunction as a central theme in ALS and FTD, and discuss the role of disease-associated RBPs in health and disease. Furthermore, we review emerging evidence regarding the prion-like properties of RBP pathology, and explore the downstream mechanisms that drive neurodegeneration. By unraveling the complex role of RBPs in ALS and FTD, we ultimately aim to provide insights into potential avenues for therapeutic intervention in these incurable disorders.

Keywords:  Amyotrophic lateral sclerosis (ALS); FTLD; FUS; Frontotemporal dementia (FTD); Liquid–liquid phase separation (LLPS); Prion-like seeding; Protein aggregation; RNA-binding proteins (RBP); TDP-43

DOI:  https://doi.org/10.1186/s13024-025-00851-y
Autophagy Rep. 2025 ;4(1): 2472450

Navigating the neuronal recycling bin: Another look at huntingtin in coordinating autophagy.

Thomas J Krzystek, Shermali Gunawardena.

  Neurons, as post-mitotic and long-lived cells, rely heavily on autophagy to maintain cellular homoeostasis and ensure proper function. Huntingtin (HTT), a protein central to Huntington's disease (HD), has emerged as a putative multifunctional regulator within the neuronal autophagy-lysosome pathway. This review explores normal HTT's multifaceted role in neuronal autophagy, from its potential involvement in autophagy induction, its capacity to influence cargo recognition and autophagosome formation, and its contribution to autophagosome-lysosome fusion and transport. We also discuss the unique challenges that neurons face in maintaining proteostasis through autophagy, emphasising the need for specialised mechanisms like axonal transport of autophagosomes and distinct regulatory pathways. Furthermore, we highlight the spatial and temporal regulation of neuronal autophagy, particularly in the context of ageing and neuronal maturation, underscoring the importance of understanding HTT's role in different neuronal states. By elucidating the intricate relationship between HTT and neuronal autophagy, this review aims to shed light on specific mechanisms of action in autophagy that can be disrupted in neurodegenerative diseases including HD.

Keywords:  Neurons; autophagy; huntingtin; huntington’s disease

DOI:  https://doi.org/10.1080/27694127.2025.2472450
J Clin Invest. 2025 Jun 02. pii: e182088. [Epub ahead of print]135(11):

TDP-43 dysregulation of polyadenylation site selection is a defining feature of RNA misprocessing in amyotrophic lateral sclerosis and frontotemporal dementia.

Frederick J Arnold, Ya Cui, Sebastian Michels, Michael R Colwin, Cameron M Stockford, Wenbin Ye, Vidhya Maheswari Jawahar, Karen Jansen-West, Julien Philippe, Ravinder Gulia, Yunzi Gou, Oliver H Tam, Sneha Menon, Wendy G Situ, Saira L Cazarez, Aryan Zandi, Kean Ck Ehsani, Sierra Howard, Dennis W Dickson, Molly Gale Hammell, Mercedes Prudencio, Leonard Petrucelli, Wei Li, Albert R La Spada.

  Nuclear clearance and cytoplasmic aggregation of TAR DNA-binding protein 43 (TDP-43) are observed in many neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Although TDP-43 dysregulation of splicing has emerged as a key event in these diseases, TDP-43 can also regulate polyadenylation; yet this has not been adequately studied. Here, we applied the dynamic analysis of polyadenylation from an RNA-Seq (DaPars) tool to ALS/FTD transcriptome datasets and report extensive alternative polyadenylation (APA) upon TDP-43 alteration in ALS/FTD cell models and postmortem ALS/FTD neuronal nuclei. Importantly, many identified APA genes highlight pathways implicated in ALS/FTD pathogenesis. To determine the functional relevance of APA elicited by TDP-43 nuclear depletion, we examined microtubule affinity regulating kinase 3 (MARK3). Nuclear loss of TDP-43 yielded increased expression of MARK3 transcripts with longer 3' UTRs, corresponding with a change in the subcellular distribution of MARK3 and increased neuronal tau S262 phosphorylation. Our findings define changes in polyadenylation site selection as a previously understudied feature of TDP-43-driven disease pathology in ALS/FTD and highlight a potentially important mechanistic link between TDP-43 dysfunction and tau regulation.

Keywords:  Genetics; Neurodegeneration; Neuroscience; RNA processing

DOI:  https://doi.org/10.1172/JCI182088
Acta Neuropathol. 2025 Jun 06. 149(1): 59

Analysis of the splicing landscape of the frontal cortex in FTLD-TDP reveals subtype specific patterns and cryptic splicing.

Júlia Faura, Bavo Heeman, Cyril Pottier, Matthew C Baker, Mariely DeJesus-Hernandez, Fahri Küçükali, Laura Heiß, Sarah Wynants, Marleen Van den Broeck, Peter De Rijk, Tim De Pooter, Geert Joris, NiCole A Finch, Yan Asmann, Mojca Strazisar, Melissa E Murray, Leonard Petrucelli, Björn Oskarsson, Kristel Sleegers, Keith A Josephs, Aivi T Nguyen, R Ross Reichard, Ronald C Petersen, Bradley F Boeve, Neill R Graff-Radford, Dennis W Dickson, Marka van Blitterswijk, Rosa Rademakers.

  Dysregulation of TDP-43 as seen in TDP-43 proteinopathies leads to specific RNA splicing dysfunction. While discovery studies have explored novel TDP-43-driven splicing events in induced pluripotent stem cell (iPSC)-derived neurons and TDP-43 negative neuronal nuclei, transcriptome-wide investigations in frontotemporal lobar degeneration with TDP-43 aggregates (FTLD-TDP) brains remain unexplored. Such studies hold promise for identifying widespread novel and relevant splicing alterations in FTLD-TDP patient brains. We conducted the largest differential splicing analysis (DSA) using bulk short-read RNAseq data from frontal cortex (FCX) tissue of 127 FTLD-TDP (A, B, C, GRN and C9orf72 carriers) and 22 control subjects (Mayo Clinic Brain Bank), using Leafcutter. In addition, long-read bulk cDNA sequencing data were generated from FCX of 9 FTLD-TDP and 7 controls and human TARDBP wildtype and knock-down iPSC-derived neurons. Publicly available RNAseq data (MayoRNAseq, MSBB and ROSMAP studies) from Alzheimer's disease patients (AD) was also analyzed. Our DSA revealed extensive splicing alterations in FTLD-TDP patients with 1881 differentially spliced events, in 892 unique genes. When evaluating differences between FTLD-TDP subtypes, we found that C9orf72 repeat expansion carriers carried the most splicing alterations after accounting for differences in cell-type proportions. Focusing on cryptic splicing events, we identified STMN2 and ARHGAP32 as genes with the most abundant and differentially expressed cryptic exons between FTLD-TDP patients and controls in the brain, and we uncovered a set of 17 cryptic events consistently observed across studies, highlighting their potential relevance as biomarkers for TDP-43 proteinopathies. We also identified 16 cryptic events shared between FTLD-TDP and AD brains, suggesting potential common splicing dysregulation pathways in neurodegenerative diseases. Overall, this study provides a comprehensive map of splicing alterations in FTLD-TDP brains, revealing subtype-specific differences and identifying promising candidates for biomarker development and potential common pathogenic mechanisms between FTLD-TDP and AD.

Keywords:  Frontotemporal dementia; Splicing; TDP-43; Transcriptomics

DOI:  https://doi.org/10.1007/s00401-025-02901-7
bioRxiv. 2025 May 15. pii: 2025.05.12.653142. [Epub ahead of print]

Automated high-throughput patch clamp electrophysiology of hiPSC-derived neuronal models.

Federica Farinelli, Isaac Ostlund, Srinidhi Rao Sripathy, Debamitra Das, Gina Shim, Sangho Myung, Richard E Straub, Brady J Maher.

The advent of human induced pluripotent stem cells (hiPSCs) and their differentiation into neurons and brain organoids has revolutionized our ability to model brain disorders in a human context. However, current technologies to assay the electrophysiological properties of human neurons in these models remain limited by throughput, as single-cell manual patch clamp is laborious and resource intensive. Here, we provide methods to perform high-throughput automated patch-clamp (APC) on hiPSC-derived neurons. We describe how to dissociate and perform voltage-clamp recordings on human neurons from three well-established protocols - 2D directed differentiation of cortical neurons, NGN2-induced neurons, and 3D cortical organoids - using the Nanion Syncropatch 384, a commercially available high-throughput APC system. Using this approach, we investigated the biophysical properties of voltage-gated sodium channels (VGSCs) and provide direct comparisons between manual and APC recordings across all three hiPSC-derived model systems. We demonstrate the capability of this automated system for pharmacological analysis of native human VGSC isoforms, which will enable compound screening approaches. Lastly, we provide methods to sort specific cellular populations within these hiPSC models using fluorescence-activated cell sorting (FACS) followed by APC. These methods and results provide a transformative and novel high-throughput technique for quantifying passive and active membrane properties in cell-type specific and/or genetically modified hiPSC-derived neurons.

DOI: https://doi.org/10.1101/2025.05.12.653142
Sci Adv. 2025 Jun 06. 11(23): eadq2742

Vimentin network dysregulation mediates neurite deficits in SNCA duplication Parkinson's patient-derived midbrain neurons.

Yanni Schneider, Aron Koller, Alina Schweigert, Marie Andert, Laura Hoffmann, Sydney O'Brien, Lukas Seebauer, Sonja Plötz, Pavel Kielkowski, Jürgen Winkler, Johannes C M Schlachetzki, Wei Xiang.

Duplication of the SNCA gene (SNCADupl), linked to elevated levels of α-synuclein (aSyn), is a genetic cause of Parkinson's disease (PD). Our prior work with human-induced pluripotent stem cell (hiPSC)-derived midbrain neurons generated from patients with PD SNCADupl identified neuritic deficits, accompanied by decreased levels of cytoskeletal element β-tubulin-III (bTubIII). To explore mechanisms underlying these effects in SNCADupl neurons, we used CRISPR-Cas9 to generate isogenic control hiPSCs. Isogenic correction of SNCA dosage restored SNCADupl-induced neurite defects and bTubIII levels. Multi-omics analyses revealed SNCADupl-induced alterations in neuronal differentiation, with a notable down-regulation of PAX6. Moreover, SNCADupl induced an up-regulation of vimentin. Further characterization revealed heightened vimentin truncation associated with altered distribution and organization. Similar changes in vimentin levels and truncation were observed in postmortem putamen tissue from patients with sporadic PD. Notably, targeting vimentin with okadaic acid and withaferin A restored bTubIII- and neurite-associated defects, suggesting its potential to prevent aSyn-mediated neuritic degeneration.

DOI: https://doi.org/10.1126/sciadv.adq2742
Cell Rep. 2025 Jun 03. pii: S2211-1247(25)00548-0. [Epub ahead of print]44(6): 115777

Astrocyte induction of disease-associated microglia is suppressed by acute exposure to fAD neurons in human iPSC triple cultures.

Alexandra M Lish, Nancy Ashour, Richard V Pearse, Paige C Galle, Gwendolyn A Orme, Sarah E Heuer, Courtney R Benoit, Kellianne D Alexander, Elyssa F L Grogan, Gizem Terzioglu, Allegra Scarpa, Andrew M Stern, Nicholas Seyfried, Vilas Menon, Tracy L Young-Pearse.

  Advancements in human induced pluripotent stem cell (hiPSC) technology have enabled co-culture models for disease modeling in physiologically relevant systems. However, co-culturing protocols face challenges in usability and consistency. Here, we introduce a robust, reproducible hiPSC-derived co-culture system integrating astrocytes, neurons, and microglia. This model leverages cryopreserved cells, enabling co-cultures within 20 days post-thaw. Comparing monocultures and tricultures, we demonstrate how cell-cell interactions shape transcriptional and functional states across all three cell types. Neurons in triculture exhibit increased spine density and activity, while astrocytes and microglia show altered responses to proinflammatory stimulation. Surprisingly, the presence of astrocytes induces upregulation of disease-associated microglia (DAM) genes, including TREM2, SPP1, APOE, and GPNMB in microglia. Additionally, while familial Alzheimer's disease neurons induce a prototypical inflammatory response in microglia, the DAM signature is significantly dampened. Collectively, this study establishes a versatile human triculture model as a valuable resource for dissecting neuron-glia interactions and their role in neurodegenerative disease.

Keywords:  APOE; Alzheimer’s disease; CP: Neuroscience; CP: Stem cell research; TREM2; astrocytes; disease-associated microglia; fAD; iPSCs; microglial states; triculture

DOI:  https://doi.org/10.1016/j.celrep.2025.115777
Neurobiol Dis. 2025 Jun 03. pii: S0969-9961(25)00202-5. [Epub ahead of print] 106986

SARM1 activation induces reversible mitochondrial dysfunction and can be prevented in human neurons by antisense oligonucleotides.

Andrea Loreto, Kaitlyn M L Cramb, Lucy A McDermott, Christina Antoniou, Ilenia Cirilli, Maria Claudia Caiazza, Elisa Merlini, Peter Arthur-Farraj, W Daniel du Preez, Elliot D Mock, Hien T Zhao, David L Bennett, Giuseppe Orsomando, Michael P Coleman, Richard Wade-Martins.

  SARM1 is a key regulator of a conserved program of axon degeneration increasingly linked to human neurodegenerative diseases. Pathological SARM1 activation causes rapid NAD consumption, disrupting cellular homeostasis and leading to axon degeneration. In this study, we develop antisense oligonucleotides (ASOs) targeting human SARM1, demonstrating robust neuroprotection against morphological, metabolic, and mitochondrial impairment in human iPSC-derived dopamine neurons induced by the lethal neurotoxin vacor, a potent SARM1 activator. Furthermore, our findings reveal that axon fragmentation can be prevented, and mitochondrial dysfunction reversed using the NAD precursor nicotinamide, a form of vitamin B3, even after SARM1 activation has occurred, when neurons are already unhealthy. This research identifies ASOs as a promising therapeutic strategy to block SARM1, and provides an extensive characterisation and further mechanistic insights that demonstrate the reversibility of SARM1 toxicity in human neurons. It also identifies the SARM1 activator vacor as a specific and reversible neuroablative agent in human neurons.

Keywords:  ASO; Axon degeneration; Mitochondrial dysfunction; Neuroablative; Nicotinamide; SARM1; Vacor

DOI:  https://doi.org/10.1016/j.nbd.2025.106986
Zhongguo Zhong Yao Za Zhi. 2025 May;50(9): 2484-2494

[Study on mechanism of naringin in alleviating cerebral ischemia/reperfusion injury based on DRP1/LRRK2/MCU axis].

Kai-Mei Tan, Hong-Yu Zeng, Feng Qiu, Yun Xiang, Zi-Yang Zhou, Da-Hua Wu, Chang Lei, Hong-Qing Zhao, Yu-Hong Wang, Xiu-Li Zhang.

  This study aims to investigate the molecular mechanism by which naringin alleviates cerebral ischemia/reperfusion(CI/R) injury through DRP1/LRRK2/MCU signaling axis. A total of 60 SD rats were randomly divided into the sham group, the model group, the sodium Danshensu group, and low-, medium-, and high-dose(50, 100, and 200 mg·kg~(-1)) naringin groups, with 10 rats in each group. Except for the sham group, a transient middle cerebral artery occlusion/reperfusion(tMCAO/R) model was established in SD rats using the suture method. Longa 5-point scale was used to assess neurological deficits. 2,3,5-Triphenyl tetrazolium chloride(TTC) staining was used to detect the volume percentage of cerebral infarction in rats. Hematoxylin-eosin(HE) staining and Nissl staining were employed to assess neuronal structural alterations and the number of Nissl bodies in cortex, respectively. Western blot was used to determine the protein expression levels of B-cell lymphoma-2 gene(Bcl-2), Bcl-2-associated X protein(Bax), cleaved cysteine-aspartate protease-3(cleaved caspase-3), mitochondrial calcium uniporter(MCU), microtubule-associated protein 1 light chain 3(LC3), and P62. Mitochondrial structure and autophagy in cortical neurons were observed by transmission electron microscopy. Immunofluorescence assay was used to quantify the fluorescence intensities of MCU and mitochondrial calcium ion, as well as the co-localization of dynamin-related protein 1(DRP1) with leucine-rich repeat kinase 2(LRRK2) and translocase of outer mitochondrial membrane 20(TOMM20) with LC3 in cortical mitochondria. The results showed that compared with the model group, naringin significantly decreased the volume percentage of cerebral infarction and neurological deficit score in tMCAO/R rats, alleviated the structural damage and Nissl body loss of cortical neurons in tMCAO/R rats, inhibited autophagosomes in cortical neurons, and increased the average diameter of cortical mitochondria. The Western blot results showed that compared to the sham group, the model group exhibited increased levels of cleaved caspase-3, Bax, MCU, and the LC3Ⅱ/LC3Ⅰ ratio in the cortex and reduced protein levels of Bcl-2 and P62. However, naringin down-regulated the protein expression of cleaved caspase-3, Bax, MCU and the ratio of LC3Ⅱ/LC3Ⅰ ratio and up-regulated the expression of Bcl-2 and P62 proteins in cortical area. In addition, immunofluorescence analysis showed that compared with the model group, naringin and positive drug treatments significantly decreased the fluorescence intensities of MCU and mitochondrial calcium ion. Meanwhile, the co-localization of DRP1 with LRRK2 and TOMM20 with LC3 in cortical mitochondria was also decreased significantly after the intervention. These findings suggest that naringin can alleviate cortical neuronal damage in tMCAO/R rats by inhibiting DRP1/LRRK2/MCU-mediated mitochondrial fragmentation and the resultant excessive mitophagy.

Keywords:  DRP1/LRRK2/MCU signaling axis; cerebral ischemia/reperfusion; cortex; mitochondrial fragmentation; mitophagy; naringin

DOI:  https://doi.org/10.19540/j.cnki.cjcmm.20250213.701
Acta Neuropathol. 2025 Jun 02. 149(1): 56

Synaptotoxic effects of extracellular tau are mediated by its microtubule-binding region.

Tomas Ondrejcak, Neng-Wei Hu, Emily Coode, Tom Campbell, Grant T Corbett, Ivan Doykov, Kevin Mills, Dominic M Walsh, Frederick J Livesey, Michael J Rowan, Igor Klyubin.

  Immunotherapies targeting extracellular tau share the premise that interrupting cell-to-cell spread of tau pathology in Alzheimer's disease (AD) will slow dementia pathogenesis. Whether these interventions affect the actions of synaptotoxic, extracellular tau species that may contribute to cognitive impairment is relatively unknown. Here, we assayed synaptic plasticity disruption in anaesthetised live rats caused by intracerebral injection of synaptotoxic tau present either in (a) secretomes of induced pluripotent stem cell-derived neurons (iNs) from people with Trisomy 21, the most common genetic cause of AD, or (b) aqueous extracts of human AD brain. Extracellular tau in iN secretomes was found to include fragments that contain the extended microtubule-binding regions of tau, MTBR/R' and adjacent C-terminal sequences. Immunodepletion or co-injection with antibodies targeting epitopes within these fragments prevented the acute disruption of synaptic plasticity by these patient-derived synaptotoxic tau preparations. Moreover, a recombinant human tau fragment encompassing the core MTBR/R'-region present in tau fibrils, tau297-391, potently mimicked the deleterious action of patient-derived tau. MTBR/R'-directed antibodies also rapidly reversed a very persistent synaptotoxic effect of soluble brain tau. Our findings reveal a hitherto relatively unexplored potential benefit of targeting extracellular MTBR/R' tau on correcting synaptic dysfunction.

Keywords:  Hippocampus; In vivo; Long-term potentiation; Mass spectrometry; Tauopathies

DOI:  https://doi.org/10.1007/s00401-025-02897-0
J Neurochem. 2025 Jun;169(6): e70115

CacyBP/SIP Protein Regulates the Length and Branching of Neuronal Processes During Cortical Development.

Katarzyna Bartkowska, Krzysztof Turlejski, Anna Filipek, Ruzanna Djavadian.

  In mammals, CacyBP/SIP (calcyclin-binding protein/Siah-1-interacting protein) is widely expressed in different types of cells, including brain cells. CacyBP/SIP is involved in various cellular processes, among them proliferation, suggesting its role in tumorigenesis. In this work, we aimed to examine the role of CacyBP/SIP in cortical brain cells during developmental neurogenesis of the cerebral cortex in the opossum, Monodelphis domestica. Our results revealed that CacyBP/SIP is expressed in neurons and oligodendrocytes but not in astrocytes within the mature six-layered opossum brain. In the developing cortex of opossums at postnatal day (P) 15, we observed higher levels of CacyBP/SIP in the cortical plate, where newly generated neurons settle, compared to the subventricular neurogenic zone, where stem/progenitor cells reside. Next, we carried out experiments on primary cell cultures derived from the cerebral cortex or the anterior commissure of the opossum at two different developmental stages. We found that inhibition of CacyBP/SIP expression did not have any impact on proliferation and differentiation of cortical neurons. However, knockdown of CacyBP/SIP resulted in excessive branching of the dendritic tree and axon arbors of cortical neurons cultured from opossums at P15, which is a developmental stage corresponding to the formation of upper cortical layers. At this stage, cortical neuron axons reach the anterior commissure, that is the main fiber tract connecting the two cerebral hemispheres in marsupials, where they become myelinated by oligodendrocytes. We examined cells cultured from the anterior commissure at P35-38 during gliogenesis and observed that CacyBP/SIP did not affect the process of oligodendrogenesis or astrogenesis. Based on our results, we suggest that CacyBP/SIP is critical for arresting the branching and lengthening of dendrites and axons during formation of the cerebral cortex.

Keywords:  CacyBP/SIP; axon; cortex; dendrites; marsupial; neuron; opossum

DOI:  https://doi.org/10.1111/jnc.70115
Dev Cell. 2025 May 27. pii: S1534-5807(25)00318-1. [Epub ahead of print]

ATG9A and ARFIP2 cooperate to control PI4P levels for lysosomal repair.

Stefano De Tito, Eugenia Almacellas, Daniel Dai Yu, Emily Millard, Wenxin Zhang, Cecilia de Heus, Christophe Queval, Javier H Hervás, Enrica Pellegrino, Ioanna Panagi, Ditte Fogde, Teresa L M Thurston, Judith Klumperman, Maximiliano Gutierrez, Sharon A Tooze.

  Lysosome damage activates multiple pathways to prevent lysosome-dependent cell death, including a repair mechanism involving endoplasmic reticulum (ER)-lysosome membrane contact sites, phosphatidylinositol 4-kinase-2a (PI4K2A), phosphatidylinositol-4 phosphate (PI4P), and oxysterol-binding protein-like proteins (OSBPLs) lipid transfer proteins. PI4K2A localizes to the trans-Golgi network and endosomes, yet how it is delivered to damaged lysosomes remains unknown. During acute sterile damage and damage caused by intracellular bacteria, we show that ATG9A-containing vesicles perform a critical role in delivering PI4K2A to damaged lysosomes. ADP ribosylation factor interacting protein 2 (ARFIP2), a component of ATG9A vesicles, binds and sequesters PI4P on lysosomes, balancing OSBPL-dependent lipid transfer and promoting the retrieval of ATG9A vesicles through the recruitment of the adaptor protein complex-3 (AP-3). Our results identify a role for mobilized ATG9A vesicles and ARFIP2 in lysosome homeostasis after damage and bacterial infection.

Keywords:  AP-3; ARFIP2; ATG9A; PI4K2A; PI4P; autophagy; lysosomal damage; lysosome; membrane trafficking

DOI:  https://doi.org/10.1016/j.devcel.2025.05.007
eNeuro. 2025 Jun 02. pii: ENEURO.0093-25.2025. [Epub ahead of print]

Generation of iPSC lines with tagged α-synuclein for visualization of endogenous protein in human cellular models of neurodegenerative disorders.

Oskar G Zetterdahl, James A Crowe, Samira Reyhani, Miriam A Güra, Ot Labastida-Botey, Aline Girard, D Sean Froese, Henrik Ahlenius, Isaac Canals.

α-Synuclein is a synaptic protein that accumulates primarily in synucleinopathies and secondarily in certain lysosomal storage disorders. However, its physiological roles in health and disease are not fully understood. In part, this has been hampered by the inability to visualize α-synuclein and its cellular localization, due to the lack of specific antibodies and faithful reporters. Here, we used CRISPR/Cas9-based genome editing to generate human induced pluripotent stem cell (iPSC) lines in which the α-synuclein (SNCA) gene has been tagged with the short HA peptide either at the N-terminus or C-terminus, or with the fluorescent protein mCherry at the C-terminus of the protein. These diverse strategies revealed the C-terminus HA-tag as the best option. C-terminus HA-tagged α-synuclein had unchanged protein expression and did not generate degradation by-products. Importantly, we show that following differentiation to neurons the C-terminus HA-tagged iPSC line had unaffected electrophysiological properties and could be used to visualize accumulation of α-synuclein upon inhibition of lysosomal function and under physiological protein levels. It is our expectation that this line and tagging approach will be very useful in further studies examining α-synuclein aggregation and its role in cellular dysfunction and neurodegeneration.Significance Statement We present an optimal genome editing strategy for incorporating the short peptide HA at the C-terminus of α-synuclein in human induced pluripotent stem cells. We also show that this newly generated C-terminus tagged line can be differentiated towards functional neurons to facilitate visualization of the protein and its accumulation upon inhibition of lysosomal function, which will be useful for studying aggregation in models of neurodegenerative diseases.

DOI: https://doi.org/10.1523/ENEURO.0093-25.2025
Front Cell Dev Biol. 2025 ;13 1569187

Synchrotron radiation FTIR microspectroscopy enables measuring dynamic cell identity patterning during human 3D differentiation.

Tanja Dučić, Francisco Rodriguez-Yañez, Elena Gonzalez-Muñoz.

  Human cell fate specification, particularly in neural development, is difficult to study due to limited access to embryonic tissues and differences from animal models. Human induced pluripotent stem cells (hiPSCs) and 3D organoid models enable the study of early human neural development, surpassing limitations of 2D cultures by incorporating crucial cell-cell and cell-matrix interactions. In this study, we used synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy to examine biomolecular profiles of 3D-differentiated organoids, specifically embryoid bodies (EBs) and neural spheroids (NS), derived from hiPSCs. SR-FTIR allowed us to analyze these organoids' cellular identity at a biomolecular level, offering a holistic view that complements specific cell markers. Our findings reveal distinct biomolecular identities in 3D organoids, with differences in DNA structure, lipid saturation, phospholipid composition, and protein conformations. This approach highlights that cellular identity is shaped by more than gene expression alone; it involves unique biomolecular compositions that can be detected even in complex, multicellular environments. By demonstrating the role of molecular configuration in cell differentiation, our findings suggest that differentiation processes extend beyond genetics, involving interdependent biochemical signals. This study demonstrates the unique efficacy SR-FTIR in analyzing human-specific 3D models for investigating complex multicellular differentiation mechanisms, offering new avenues for understanding the biochemical basis of human development and disease.

Keywords:  3D embryoid bodies; IPSC; SR-FTIR; biomolecular conformation; cell identity; human morphogenesis; neural spheroids

DOI:  https://doi.org/10.3389/fcell.2025.1569187
FASEB J. 2025 Jun 15. 39(11): e70683

Regulation of Axonal Microtubule Polarity Orientation in Different Kinds of Neurons.

Ankita Patil, Shrobona Guha, Ilgin Isiltan, Hemalatha Muralidharan, Kirankumar Madugula, Peter W Baas.

  Microtubules (MTs) in the axon are nearly all oriented with plus-end-out, and this pattern of organization is important for regulating the morphology and cytoplasmic composition of the axon, and for defining the cargoes transported in the anterograde and retrograde directions in the axon. Over the past several years, studies on vertebrate neurons (and also insect neurons) have been conducted by many investigators to understand the mechanisms that establish this pattern and maintain it over the life of the neuron and in the face of potential corruption. Studies on cultured rat sympathetic neurons from superior cervical ganglia (and also insect neurons) have implicated sliding of MTs by cytoplasmic dynein as crucial not only for establishing the plus-end-out orientation of axonal MTs but also for clearing mal-oriented MTs from the axon. Studies on cultured rat hippocampal neurons have implicated TRIM46 and augmin, proteins that regulate the crosslinking and nucleation of MTs, respectively. Here we show that the axons of hippocampal neurons also require dynein-based mechanisms for regulating their MT polarity pattern; however, the axons of sympathetic neurons do not require either TRIM46 or augmin. We also show that, in hippocampal neurons but not sympathetic neurons, the axon's MT polarity pattern is corrupted when a portion of the available Kinesin-1 is pharmacologically shifted from organelle transport to MT sliding. Collectively these results indicate that the mechanisms that regulate the MT polarity pattern of the axon are not entirely the same for different kinds of neurons, even in the same animal.

Keywords:  axon; dynein; kinesin‐1; microtubule; microtubule polarity orientation; neuron

DOI:  https://doi.org/10.1096/fj.202500675RR
Elife. 2025 Jun 06. pii: RP96675. [Epub ahead of print]13

Clearance of protein aggregates during cell division.

Shoukang Du, Yuhan Wang, Bowen Chen, Shuangshuang Xie, Kuan Yoow Chan, David C Hay, Ting Gang Chew.

  Protein aggregates are spatially organized and regulated in cells to prevent the deleterious effects of proteostatic stress. Misfolding of proteins in the endoplasmic reticulum (ER) results in aggregate formation, but how the aggregates are processed, especially during cell division is not well understood. Here, we induced proteostatic stress and protein aggregation using a proteostasis reporter, which is prone to misfolding and aggregation in the ER. Unexpectedly, we detected solid-like protein aggregates deposited mainly in the nucleus and surrounded by the ER membrane. The membrane-bound aggregates were then cleared as cells progressed through mitosis and cytokinesis. Aggregate clearance depended on Hsp70 family chaperones in the ER, particularly BiP, and proteasomal activity. The clearance culminated at mitotic exit and required cyclin-dependent kinase 1 (Cdk1) inactivation but was independent of the anaphase-promoting complex (APC/C). The ER reorganization that is active during mitosis and cytokinesis was required for the aggregate clearance. Thus, dividing cells reorganize the ER networks to allow BiP to clear the protein aggregates to maintain proteostasis in the newly divided cells.

Keywords:  ER reorganization; aggregates; cell biology; chaperone; human; mitosis; proteostasis

DOI:  https://doi.org/10.7554/eLife.96675
World J Biol Chem. 2025 Jun 05. 16(2): 106850

Stem cell therapy for Parkinson's disease: A new hope for neural regeneration.

Yasmin Garkani Mokhtari, Irene Varnava, Kosmas Kyrgiannis, Vasiliki Ampatsidou, Dimitrios Giakoumettis.

  Parkinson's disease (PD) is a progressive neurodegenerative disorder marked by the loss of dopaminergic neurons in the substantia nigra that leads to reduced dopamine levels and impaired motor function. Current treatments only provide temporary symptom relief without addressing the underlying neuronal loss. A promising new approach for treating PD is stem cell therapy, particularly induced pluripotent stem cells and human pluripotent stem cells. They have the ability to differentiate into various neural cells, offering potential for neuronal replacement and restoration of brain function. Induced pluripotent stem cells are derived from reprogramming adult cells and present advantages such as genetic compatibility and reduced immune rejection, overcoming ethical concerns associated with embryonic stem cells. Preclinical studies show promising results, demonstrating that stem cells can differentiate into dopaminergic neurons and improve motor function in animal models. These advancements pave the way for clinical trials and potential long-term solutions for patients with PD. This review highlighted the significance of stem cell therapy in neuroregeneration and addressed preclinical successes, challenges in long-term safety, and ethical considerations, with the hope of revolutionizing PD treatment and improving patient outcomes.

Keywords:  Adult stem cells; Human pluripotent stem cells; Induced pluripotent stem cells; Parkinson’s disease; Stem cells

DOI:  https://doi.org/10.4331/wjbc.v16.i2.106850
MicroPubl Biol. 2025 ;2025

har-1/CHCHD10 mutations induce neurodegeneration and mitochondrial fragmentation in Caenorhabditis elegans.

Audrey Labarre, Ericka Guitard, Gilles Tossing, J Alex Parker.

CHCHD10 encodes a mitochondrial protein that plays a role in cristae morphology and oxidative phosphorylation, with mutations associated with neurodegenerative diseases, including the spectrum of amyotrophic lateral sclerosis and frontotemporal dementia (ALS-FTD). The Caenorhabditis elegans ortholog of CHCHD10 is har-1 , which can be used to model CHCHD10-related neurodegenerative diseases. We focused on two har-1 mutant strains: one featuring a 260 bp deletion ( gk3124 ) and the other with a G73E point mutation ( ad2155 ). Both har-1 mutants displayed progressive paralysis, degeneration of GABAergic motor neurons, and mitochondrial fragmentation. These strains may be valuable tools for investigating pathogenic mechanisms and therapeutic strategies for neurodegenerative diseases.

DOI: https://doi.org/10.17912/micropub.biology.001597
Neurobiol Dis. 2025 Jun 03. pii: S0969-9961(25)00191-3. [Epub ahead of print] 106975

Comprehensive characterization and validation of the Prp-hPFN1G118V mouse model: Guidelines for preclinical therapeutic testing for ALS.

Kaly A Mueller, Emma G Suneby, Matthew H Ferola, Andy J Moreno, Joshua D Kidd, Kenneth Thompson, Fernando G Vieira, Gregorio Valdez, Theo Hatzipetros.

  The hPFN1G118V mouse model, overexpressing mutant human profilin1 linked to a rare form of ALS, was comprehensively characterized to assess its suitability for preclinical drug testing. Using a large cohort of nearly 250 transgenic and wild-type mice in a longitudinal study, we combined behavioral, electrophysiological, and neuropathological assessments to define the chronology of pathological events and assess inherent subject variability. The early stage of the disease in this model was characterized by elevated plasma neurofilament light chain levels, an effect that persisted and progressed throughout the course of the disease, followed by spinal cord neuroinflammation, suggesting that axonal pathology is the initiating event. The middle stage of the disease involved progressive neuromuscular decline, including reductions in compound muscle action potential (CMAP) and grip strength, accompanied by neuromuscular junction degeneration. The end-stage of the disease was characterized by the onset of visible changes such as weight loss, gait abnormalities and hindlimb paresis that quickly progressed to paralysis. At end-stage we also observed spinal motor neuron loss and TDP-43 pathology. The average humane endpoint was 213 days for females and 237 days for males. Our findings demonstrate that hPFN1G118V mice recapitulate key ALS features with moderate disease progression and a reproducible disease course, making them a valuable model for therapeutic testing. Recommendations are provided to optimize study design for preclinical testing, emphasizing survival duration as the primary endpoint, with CMAP and plasma NFL as key secondary readouts.

Keywords:  Amyotrophic lateral sclerosis; CMAP; Motor neurons; Neurodegeneration; Neurofilament light chain; Neuroinflammation; Profilin1

DOI:  https://doi.org/10.1016/j.nbd.2025.106975
J Biol Chem. 2025 May 30. pii: S0021-9258(25)02172-6. [Epub ahead of print] 110322

Myristoylation of TMEM106B by NMT1/2 regulates TMEM106B trafficking and turnover.

Alexander Lacrampe, Dan Hou, Isis G Perez, Belvin Gong, Natalia Franco-Hernandez, Angie Yee, Wenzhe Chen, Maxime Ah Young-Chapon, Hening Lin, Fenghua Hu.

  TMEM106B, a type II transmembrane protein localized on the lysosomal membrane, has been identified as a central player in neurodegeneration and brain aging during the past decade. TMEM106B variants that increase TMEM106B expression levels are linked to several neurodegenerative diseases, including frontotemporal lobar degeneration (FTLD). Additionally, the C-terminal lumenal fragment of TMEM106B was recently shown to form amyloid fibrils during aging and neurodegeneration. However, the mechanisms regulating TMEM106B levels are not well understood. Here we show that TMEM106B is myristoylated by NMT1/2 enzymes at its glycine 2 α-amino group and its lysine 3 ε-amino group. Myristoylation decreases TMEM106B levels by promoting its lysosomal degradation. Furthermore, we demonstrate that TMEM106B C-terminal fragments (CTFs) can be detected under physiological conditions and the levels of CTFs are regulated by myristoylation and lysosomal activities. In addition, we show that non-myristoylated TMEM106B accumulates on the cell surface, indicating that myristoylation affects TMEM106B trafficking within the cell. Taken together, these findings suggest that TMEM106B myristoylation is an important mechanism regulating its function, trafficking, and turnover.

Keywords:  Lysosome; Myristoylation; NMT1/2; TMEM106B

DOI:  https://doi.org/10.1016/j.jbc.2025.110322
Differentiation. 2025 May 22. pii: S0301-4681(25)00036-2. [Epub ahead of print]143 100869

Progression of differentiation of iPSCs into specific subtypes of neurons.

Jingwen Wang, Ruijie Ji, Lei Zhang, Xiang Cheng, Xinhua Zhang.

  Induced pluripotent stem cells (iPSCs), generated through somatic cell reprogramming, exhibit self-renewal capacity and multilineage differentiation potential. In recent years, iPSC-derived neurons have emerged as a significant platform for researching mechanisms and developing therapies for neurological diseases. This paper reviews the targeted differentiation strategies of iPSCs into dopaminergic neurons, motor neurons, cholinergic neurons and medium spinal neurons, providing detailed insights into the differentiation processes. Additionally, this paper discusses the challenges associated with the future application of iPSCs-derived neurons in the treatment of nervous system diseases are also discussed in this paper, aiming to provide references for the application of iPSCs in cellular therapies for neurodegenerative disorders.

Keywords:  Cytokines; Differentiation method; Induced pluripotent stem cells; Neurodegenerative diseases; Neuron

DOI:  https://doi.org/10.1016/j.diff.2025.100869
Mol Neurobiol. 2025 Jun 04.

Differentiation of SH-SY5Y Cells into Cortical Neuron-like Cells for Tauopathy Modeling and Seeding Assays.

Alexander Devyatov, Ihor Kozlov, Viswanath Das.

  SH-SY5Y cells are widely used as an in vitro neuronal model, yet reliable differentiation protocols tailored for tauopathy research remain limited. Effective differentiation is essential for studying tau aggregation, propagation, and neurodegenerative mechanisms. Here, we present an optimized two-step differentiation protocol for TauP301L-expressing SH-SY5Y cells that enhances neuronal maturation and tauopathy modeling, providing a physiologically relevant system for investigating tau seeding. SH-SY5Y cells expressing TauP301L-EGFP under an inducible system were differentiated using a two-step protocol consisting of retinoic acid (RA) for 72 h, followed by brain-derived neurotrophic factor (BDNF) and RA for 72 h. Differentiated neurons were then exposed to exogenous P301L tau peptide fibrils to assess their susceptibility to tau seeding and aggregation. Differentiation resulted in increased neurite outgrowth, cholinergic marker expression (ChAT upregulation, TH downregulation), and upregulation of the mature 2N4R tau isoform. Western blot analysis showed increased T22 and pSer262 tau immunoreactivity in seeded cells, consistent with tau conformational changes and pathological phosphorylation. These findings may reflect early stages of tau misfolding but do not confirm oligomer formation. Seeding also induced neurite remodeling, varicosity formation, and reduced neurite diameter-features consistent with tau-mediated pathology involving cytoskeletal changes, organelle accumulation, or axonal transport defects. This optimized differentiation protocol provides an experimentally tractable tauopathy model for investigating tau propagation and neuronal dysfunctions in a controlled human cell context. Compared to existing SH-SY5Y differentiation methods, our system provides faster neuronal maturation, controlled TauP301L induction, and enhanced tau isoform expression, making it a valuable platform for studying early tau misfolding events and therapeutic interventions in tauopathies.

Keywords:  Alzheimer’s disease; Choline Acetyltransferase; Neurodegenerative disease; SH-SY5Y; Tau; Tyrosine Hydroxylase; Vesicular glutamate transporter 1

DOI:  https://doi.org/10.1007/s12035-025-05100-3
Neurobiol Aging. 2025 May 26. pii: S0197-4580(25)00088-0. [Epub ahead of print]153 1-9

Processivity and BDNF-dependent modulation of signalling endosome axonal transport are impaired in mice with advanced age.

David Villarroel-Campos, Elena R Rhymes, Andrew P Tosolini, Bilal Malik, Alessio Vagnoni, Giampietro Schiavo, James N Sleigh.

  A healthy nervous system is reliant upon an efficient transport network to deliver essential cargoes throughout the extensive and polarised architecture of neurons. The trafficking of cargoes, such as organelles and proteins, is particularly challenging within the long projections of neurons, which, in the case of axons, can be more than four orders of magnitude longer than cell bodies. It is therefore unsurprising that disruptions in axonal transport have been reported across neurological diseases. A decline in this essential process has also been identified in many aging models, perhaps compounding age-related neurodegeneration. Via intravital imaging, we recently determined that, despite a reduction in overall motility, the run speed and displacement of anterograde mitochondrial transport were unexpectedly enhanced in 19-22 month-old mouse peripheral nerves. Here, to determine how aging impacts a different axonal cargo, we evaluated in vivo trafficking of signalling endosomes in motor axons of mouse sciatic nerves from 3 to 22 months. Contrasting with mitochondria, we did not detect alterations in signalling endosome speed, but found a consistent rise in pausing that manifested after 18 months. We then treated muscles with brain-derived neurotrophic factor (BDNF), which regulates axonal transport of signalling endosomes in motor neurons; however, we observed no change in the processivity defect at 22 months, consistent with downregulation of the BDNF receptor TrkB at the neuromuscular junction. Together, these findings indicate that aging negatively impacts signalling endosome trafficking in motor axons, likely through dampened BDNF signalling at the motor neuron-muscle interface.

Keywords:  Aged; Aging; Intravital imaging; Motor neuron; Neurotrophins; Sciatic nerve; Signalling endosomes; Tropomyosin receptor kinase B (TrkB)

DOI:  https://doi.org/10.1016/j.neurobiolaging.2025.05.002
Curr Opin Plant Biol. 2025 Jun 03. pii: S1369-5266(25)00054-8. [Epub ahead of print]86 102740

Wet scissors: How biomolecular condensates cut cellular membranes.

Xiaofeng Fang, Alexander I May, Katharina Sporbeck, Lukas Hauer, Roland L Knorr.

Membrane shape is a fundamental determinant of cellular organisation. Reshaping of membranes is crucial for dynamic processes including organelle and cell division, endocytosis and membrane trafficking. Membrane fission (or scission) is a discontinuous, topological shape change that is central in many such processes. Specialised remodelling proteins, such as dynamins and ESCRT proteins, are capable of forming oligomeric spirals that drive membrane fission in cells. In this review, we summarise evidence demonstrating that capillary forces generated by liquid-like biomolecular condensates can facilitate cellular membrane reshaping and drive fission events. We draw on our recent findings that condensates are implicated in multivesicular body formation to describe the molecular and physical principles that allow biomolecular condensates to cut membranes. We further discuss possible interactions between novel condensate-mediated fission processes and established reshaping processes. We propose that condensates make an important contribution to membrane remodelling events involved in the biogenesis of diverse cellular structures. The characterisation of condensate-mediated membrane reshaping promises to transform our understanding of intracellular organisation and dynamics.

DOI: https://doi.org/10.1016/j.pbi.2025.102740
J Neuroinflammation. 2025 Jun 02. 22(1): 147

Inflammation-induced lysosomal dysfunction in human iPSC-derived microglia is exacerbated by APOE 4/4 genotype.

Marianna Hellén, Isabelle Weert, Stephan A Müller, Noora Räsänen, Pinja Kettunen, Šárka Lehtonen, Michael Peitz, Klaus Fließbach, Mari Takalo, Marja Koskuvi, Stefan F Lichtenthaler, Ville Leinonen, Alfredo Ramirez, Olli Kärkkäinen, Mikko Hiltunen, Jari Koistinaho, Taisia Rõlova.

   BACKGROUND: The ε4 isoform of apolipoprotein E (ApoE) is the most significant genetic risk factor for Alzheimer's disease. Glial cells are the main source of ApoE in the brain, and in microglia, the ε4 isoform of ApoE has been shown to impair mitochondrial metabolism and the uptake of lipids and Aβ42. However, whether the ε4 isoform alters autophagy or lysosomal activity in microglia in basal and inflammatory conditions is unknown.
METHODS: Altogether, microglia-like cells (iMGs) from eight APOE3/3 and six APOE4/4 human induced pluripotent stem cell (iPSC) lines were used in this study. The responses of iMGs to Aβ42, LPS and IFNγ were studied by metabolomics, proteomics, and functional assays.
RESULTS: Here, we demonstrate that iMGs with the APOE4/4 genotype exhibit reduced basal pinocytosis levels compared to APOE3/3 iMGs. Inflammatory stimulation with a combination of LPS and IFNγ or Aβ42 induced PI3K/AKT/mTORC signaling pathway, increased pinocytosis, and blocked autophagic flux, leading to the accumulation of sequestosome 1 (p62) in both APOE4/4 and APOE3/3 iMGs. Exposure to Aβ42 furthermore caused lysosomal membrane permeabilization, which was significantly stronger in APOE4/4 iMGs and positively correlated with the secretion of the proinflammatory chemokine IL-8. Metabolomics analysis indicated a dysregulation in amino acid metabolism, primarily L-glutamine, in APOE4/4 iMGs.
CONCLUSIONS: Overall, our results suggest that inflammation-induced metabolic reprogramming places lysosomes under substantial stress. Lysosomal stress is more detrimental in APOE4/4 microglia, which exhibit endo-lysosomal defects.

Keywords:  Alzheimer’s disease; Apolipoprotein E; Lysosomal dysfunction; Microglia; iPSC

DOI:  https://doi.org/10.1186/s12974-025-03470-y
bioRxiv. 2025 May 23. pii: 2025.05.20.655155. [Epub ahead of print]

Dissociation of the mTOR protein interaction network following neuronal activation is altered by Shank3 mutation.

Devin T Wehle, Emily A Brown, Vera Stamenkovic, Felicia Harsh, Stephen E P Smith.

The mechanistic target of Rapamycin (mTOR) kinase pathway plays critical roles in neuronal function and synaptic plasticity, and its dysfunction is implicated in numerous neurological and psychiatric disorders. Traditional linear models depict mTOR signaling as a sequential phosphorylation cascade, but accumulating evidence supports a model that includes signaling through dynamic protein-protein interaction networks. To examine how neuronal mTOR signaling discriminates between distinct stimuli, we quantified phosphorylation events and protein co-association networks in primary mouse cortical neurons. Unexpectedly, neuronal mTOR activation by IGF or glutamate triggered dissociation-rather than the anticipated assembly-of protein complexes involving mTOR complex1 (TORC1), mTOR complex 2 (TORC2), and translational machinery, distinguishing neurons from proliferative cells. Applying in vitro homeostatic scaling paradigms revealed distinct combinatorial encoding of synaptic scaling direction: both up- and down-scaling induced dissociation of translational complexes, but downscaling uniquely included dissociation of upstream pathway regulators. Cortical neurons from Shank3B knockout mice, modeling autism-associated Phelan-McDermid Syndrome, displayed baseline hyperactivation of the mTOR network, which reduced the dynamic range of network responses to homeostatic scaling and pharmacological inhibition. These findings reveal that neuronal mTOR signaling employs stimulus-specific combinations of dissociative protein interaction modules to encode opposing forms of synaptic plasticity.

DOI: https://doi.org/10.1101/2025.05.20.655155
Cell Death Dis. 2025 Jun 03. 16(1): 418

Down-regulation of neuroprotective protein kinase D in Huntington´s disease.

Álvaro Sebastián-Serrano, Ana Simón-García, María Santos-Galindo, Marina Prudencio Sánchez-Carralero, Alberto H-Alcántara, Cristina Clemente, Julia Pose-Utrilla, Miguel R Campanero, Eva Porlan, José J Lucas, Teresa Iglesias.

Huntington's disease (HD) is a progressive, autosomal dominant neurodegenerative disorder characterized by the selective dysfunction and loss of neurons in the striatum and cerebral cortex. Experimental evidence suggests that GABAergic medium-sized spiny neurons (MSNs) in the striatum are particularly vulnerable to glutamate-induced toxicity (excitotoxicity) and its analogues. However, the molecular mechanisms underlying MSN-specific death in HD remain poorly understood. The serine/threonine protein kinase D1 (PKD1) confers neuroprotection in various neuropathological conditions, including ischemic stroke. While excitotoxicity inactivates PKD1 in cortical glutamatergic neurons without altering its levels, active PKD1 potentiates the survival of excitatory neurons in highly excitotoxic environments. Here, we investigated whether PKD1 activity dysregulation contributes to MSN death in HD and its association with neurodegeneration. We found an unexpected reduction in PKD1 protein levels in striatal neurons from HD patients. Similarly, the R6/1 mouse model of HD exhibited progressive PKD1 protein loss, commencing at early disease stages, accompanied by decreased Prkd1 transcript levels. PKD1 downregulation also occurred in the cerebral cortex of R6/1 mice, but only at late stages. Functionally, pharmacological PKD inhibition in primary striatal neurons exacerbated excitotoxic damage and apoptosis induced by glutamate N-methyl D-aspartate (NMDA) receptors, whereas expression of constitutively active PKD1 (PKD1-Ca) conferred neuroprotection. Furthermore, PKD1-Ca protected against polyQ-induced apoptosis in a cellular model of HD. In a translational approach, intrastriatal lentiviral delivery of PKD1-Ca in symptomatic R6/1 mice prevented the loss of DARPP-32, a molecular marker of MSNs. Collectively, our findings strongly suggest that PKD1 loss-of-function contributes to HD pathogenesis and the selective vulnerability of MSNs. These findings position PKD1 as a promising therapeutic target for mitigating MSN death in HD.

DOI: https://doi.org/10.1038/s41419-025-07688-9
Sci Adv. 2025 Jun 06. 11(23): eadu9605

HOPS-dependent vesicle tethering lock inhibits endolysosomal fusions and autophagosome secretion upon the loss of Syntaxin17.

Dávid Hargitai, Anikó Nagy, Iván Bodor, Győző Szenci, Hajnalka Laczkó-Dobos, Arindam Bhattacharjee, Natali Neuhauser, Szabolcs Takáts, Gábor Juhász, Péter Lőrincz.

The autophagosomal SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein) Syntaxin17 (Syx17) plays a pivotal role in autophagosome-lysosome fusion, yet the broader impact of its loss remains elusive. Our investigation of Syx17 function in Drosophila nephrocytes and salivary gland cells revealed unexpected effects. We find that Syx17 loss induces the formation of autophagosome-lysosome clusters in a HOPS (homotypic fusion and vacuole protein sorting)-dependent manner, entrapping this tether, autophagosomes, and lysosomes. While locked in clusters, these organelles cannot participate in other vesicle fusions, impeding endosomal progression and autophagosome secretion. Therefore, the absence of Syx17 not only inhibits autophagosome-lysosome fusion but also prevents HOPS release from autophagosome-lysosome tethering sites causing a "tethering lock." Preventing autophagosome formation or removing the HOPS adaptor Plekhm1 (pleckstrin homology domain-containing family M member 1) leads to release of HOPS and lysosomes from these clusters, thus rescuing secondary effects of Syx17 loss. Our findings show that a tethering lock can disrupt multiple vesicle trafficking routes.

DOI: https://doi.org/10.1126/sciadv.adu9605
Curr Opin Cell Biol. 2025 Jun 03. pii: S0955-0674(25)00082-1. [Epub ahead of print]95 102544

RAS/ERK signaling and PLK1: Coordinating developmental regulation and disease mechanisms.

Han Bit Baek, Swathi Arur.

The RAS/ERK signaling pathway is a critical regulator of cellular processes such as proliferation, differentiation, and survival, core mechanisms that drive development. Dysregulation of RAS/ERK signaling is implicated in developmental disorders, including RASopathies, as well as in various cancers. Polo-like kinase 1 (PLK1) is a crucial orchestrator of both meiotic and mitotic cell cycle and plays an equally important role in development. Notably, abnormal ERK signaling can produce phenotypes that closely resemble those caused by PLK1 deficiency, suggesting a functional intersection between these pathways. In this review, we explore the emerging links between RAS/ERK and PLK1 signaling during development and highlight the broad range of biological processes potentially governed by their interaction.

DOI: https://doi.org/10.1016/j.ceb.2025.102544
Curr Res Toxicol. 2025 ;8 100229

Characterization of extracellular vesicles and miRNA released by cerebral organoids.

Brian B Silver, Rick Fannin, Kevin Gerrish, Erik J Tokar.

  Environmental toxicants can contribute to the development of several neurodegenerative diseases. However, the mechanisms behind this pathology are still incompletely understood. Prompt diagnosis of impending neurodegeneration is crucial for early interventions to prevent cognitive decline. Towards this end, accurate biomarkers for early neurodegenerative processes and exposure risk are needed. Extracellular vesicles (EVs) are lipid particles released by cells which contain many bioactive molecules including miRNAs. EVs may serve both as a route of propagating neurotoxic phenotypes and as a source of biomarkers for neurological disease. However, the exact mechanisms though which EVs could spread the deleterious effects of toxicants and the full spectrum of their usage as biomarkers remain unclear. Organoid models have several advantages, including potential for use in high-throughput toxicant testing and applications in personalized medicine and disease models. However, few studies have examined EV release in brain organoids to determine if the EVs could contain useful biomarkers. We employed several technologies to characterize EVs released by human cerebral organoids and their associated miRNAs. We identified that cerebral organoids consistently release EV-associated miRNA in quantities sufficient for robust analysis with NanoString. Further, pathway analyses revealed that terms related to neurodegenerative disease and nervous system signaling are associated with the recovered miRNAs. Together, these data suggest that cerebral organoids have utility as a tool for the discovery of EV-associated miRNAs involved in neurodegenerative disease and neurotoxicity.

Keywords:  Cerebral organoids; Extracellular vesicles; Neurodegenerative disease; Neurotoxicity; New approach methodologies; microRNA

DOI:  https://doi.org/10.1016/j.crtox.2025.100229