bims-axbals Biomed News
on Axonal biology and ALS
Issue of 2025–04–27
35 papers selected by
TJ Krzystek
  1. Loss of intracellular ATP affects axoplasmic viscosity and pathological protein aggregation in mammalian neurons.
  2. Opposing roles for GSK3β and ERK1-dependent phosphorylation of huntingtin during neuronal dysfunction and cell death in Huntington's disease.
  3. Mitophagy in Neurons: Mechanisms Regulating Mitochondrial Turnover and Neuronal Homeostasis.
  4. Intersecting impact of CAG repeat and huntingtin knockout in stem cell-derived cortical neurons.
  5. Loss of neuronal Imp contributes to seizure behavior through Syndecan function.
  6. Lysosomal TPC2 channels disrupt Ca2+ entry and dopaminergic function in models of LRRK2-Parkinson's disease.
  7. Spinal Cord Organoids from Human Amniotic Fluid iPSC Recapitulate the Diversity of Cell Phenotypes During Fetal Neural Tube Morphogenesis.
  8. OPA1 mutations in dominant optic atrophy: domain-specific defects in mitochondrial fusion and apoptotic regulation.
  9. Generation of human induced pluripotent stem cell-derived cortical neurons expressing the six tau isoforms.
  10. iPSC-derived and Patient-Derived Organoids: Applications and challenges in scalability and reproducibility as pre-clinical models.
  11. Semi-automated Analysis of Beading in Degenerating Axons.
  12. Molecular Biomarkers of Neurodegeneration in Amyotrophic Lateral Sclerosis.
  13. Polarized subcellular activation of Rho proteins by specific ROPGEFs drives pollen germination in Arabidopsis thaliana.
  14. Rab32 regulates Golgi structure and cell migration through Protein Kinase A-mediated phosphorylation of Optineurin.
  15. Pathogenetic Involvement of Autophagy and Mitophagy in Primary Progressive Multiple Sclerosis.
  16. Kinetin mediated mutant huntingtin phosphorylation restores multiple dysregulated pathways in a cell line model of Huntington's disease.
  17. Tau aggregation induces cell death in iPSC-derived neurons.
  18. TMBIM-2 links neuronal mitochondrial stress to systemic adaptation via calcium signaling.
  19. Mitochondrial calpain-1 truncates ATP synthase beta subunit.
  20. Mitochondrial fission surveillance is coupled to Caenorhabditis elegans DNA and chromosome segregation integrity.
  21. Autophagosomes anchor an AKAP11-dependent regulatory checkpoint that shapes neuronal PKA signaling.
  22. Cell biology: Mitochondrial protease degrades unoccupied translocases upon import stress.
  23. Organoids in disease modeling and regenerative medicine.
  24. Theory of axo-axonic inhibition.
  25. A Novel Mutation in CNTNAP1 Gene Causes Disorganization of Axonal Domains, Hypomyelination and Severe Neurological Deficits.
  26. Induced Pluripotent Stem Cells-Based Regenerative Therapies in Treating Human Aging-Related Functional Decline and Diseases.
  27. The four most common genetic subtypes of amyotrophic lateral sclerosis: state of the art and future directions.
  28. Generation of human induced pluripotent stem cell lines derived from a patient carrying an intragenic deletion in the NFIA gene.
  29. Resolving Conformational Plasticity in Mammalian Cells with High-Resolution Fluorescence Tools.
  30. Activity-dependent refinement of axonal projections forms one-to-one connection pattern in the developing chick ciliary ganglion.
  31. Challenges and advances for huntingtin detection in cerebrospinal fluid: in support of relative quantification.
  32. Increased TMEM106B levels lead to lysosomal dysfunction which affects synaptic signaling and neuronal health.
  33. Neuronal autophagy controls excitability via ryanodine receptor-mediated regulation of calcium-activated potassium channel function.
  34. Neural Responses to Hypoxic Injury in a Vascularized Cerebral Organoid Model.
  35. UCHL1-Mediated Spastin Degradation Regulates Microtubule Severing and Hippocampal Neurite Outgrowth.
  1. Sci Adv. 2025 Apr 25. 11(17): eadq6077
    Loss of intracellular ATP affects axoplasmic viscosity and pathological protein aggregation in mammalian neurons.
    Laurent Guillaud, Anna Garanzini, Sarah Zakhia, Sandra De la Fuente, Dimitar Dimitrov, Susan Boerner, Marco Terenzio.
      Neurodegenerative diseases display synaptic deficits, mitochondrial defects, and protein aggregation. We show that intracellular adenosine triphosphate (ATP) regulates axoplasmic viscosity and protein aggregation in mammalian neurons. Decreased intracellular ATP upon mitochondrial inhibition leads to axoterminal cytosol, synaptic vesicles, and active zone component condensation, modulating the functional organization of mouse glutamatergic synapses. Proteins involved in the pathogenesis of Parkinson's disease (PD), Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS) condensed and underwent ATP-dependent liquid phase separation in vitro. Human inducible pluripotent stem cell-derived neurons from patients with PD and ALS displayed reduced axoplasmic fluidity and decreased intracellular ATP. Last, nicotinamide mononucleotide treatment successfully rescued intracellular ATP levels and axoplasmic viscosity in neurons from patients with PD and ALS and reduced TAR DNA-binding protein 43 (TDP-43) aggregation in human motor neurons derived from a patient with ALS. Thus, our data suggest that the hydrotropic activity of ATP contributes to the regulation of neuronal homeostasis under both physiological and pathological conditions.
    DOI:  https://doi.org/10.1126/sciadv.adq6077
  2. Cell Death Dis. 2025 Apr 22. 16(1): 328
    Opposing roles for GSK3β and ERK1-dependent phosphorylation of huntingtin during neuronal dysfunction and cell death in Huntington's disease.
    Thomas J Krzystek, Rasika Rathnayake, Jia Zeng, Jing Huang, Gary Iacobucci, Michael C Yu, Shermali Gunawardena.
      Huntington's disease (HD) is a devastating neurodegenerative disorder that manifests from an N-terminal polyQ-expansion (>35) in the Huntingtin (HTT) gene leading to axonal degeneration and significant neuronal death. Despite evidence for a scaffolding role for HTT in membrane-related processes such as endocytosis, vesicle transport, and vesicle fusion, it remains unclear how polyQ-expansion alters membrane binding during these processes. Using quantitative Mass Spectrometry-based proteomics on HTT-containing light vesicle membranes isolated from healthy and HD iPSC-derived neurons, we found significant changes in the proteome and kinome of signal transduction, neuronal translation, trafficking, and axon guidance-related processes. Through a combination of in vitro kinase assays, Drosophila genetics, and pharmacological inhibitors, we identified that GSK3β and ERK1 phosphorylate HTT and that these events play distinct and opposing roles during HD with inhibition of GSK3β decreasing polyQ-mediated axonal transport defects and neuronal cell death, while inhibition of ERK enhancing these phenotypes. Together, this work proposes two novel pathways in which GSK3β phosphorylation events exacerbate and ERK phosphorylation events mitigate HD-dependent neuronal dysfunction highlighting a highly druggable pathway for targeted therapeutics using already available small molecules.
    DOI:  https://doi.org/10.1038/s41419-025-07524-0
  3. J Mol Biol. 2025 Apr 21. pii: S0022-2836(25)00227-X. [Epub ahead of print] 169161
    Mitophagy in Neurons: Mechanisms Regulating Mitochondrial Turnover and Neuronal Homeostasis.
    Bishal Basak, Erika L F Holzbaur.
      Mitochondrial quality control is instrumental in regulating neuronal health and survival. The receptor-mediated clearance of damaged mitochondria by autophagy, known as mitophagy, plays a key role in controlling mitochondrial homeostasis. Mutations in genes that regulate mitophagy are causative for familial forms of neurological disorders including Parkinson's disease (PD) and Amyotrophic lateral sclerosis(ALS). PINK1/Parkin-dependent mitophagy is the best studied mitophagy pathway, while more recent work has brought to light additional mitochondrial quality control mechanisms that operate either in parallel to or independent of PINK1/Parkin mitophagy. Here, we discuss our current understanding of mitophagy mechanisms operating in neurons to govern mitochondrial homeostasis. We also summarize progress in our understanding of the links between mitophagic dysfunction and neurodegeneration and highlight the potential for therapeutic interventions to maintain mitochondrial health and neuronal function.
    Keywords:  PINK1; Parkin; autophagosomes; lysosomes; mitochondria; mitophagy; neurodegeneration
    DOI:  https://doi.org/10.1016/j.jmb.2025.169161
  4. Neurobiol Dis. 2025 Apr 19. pii: S0969-9961(25)00130-5. [Epub ahead of print] 106914
    Intersecting impact of CAG repeat and huntingtin knockout in stem cell-derived cortical neurons.
    Jennifer T Stocksdale, Matthew J Leventhal, Stephanie Lam, Yu-Xin Xu, Yang Oliver Wang, Keona Q Wang, Reuben Tomas, Zohreh Faghihmonzavi, Yogi Raghav, Charlene Smith, Jie Wu, Ricardo Miramontes, Kanchan Sarda, Heather Johnson, Min-Gyoung Shin, Terry Huang, Mikelle Foster, Mariya Barch, Naufa Armani, Chris Paiz, Lindsay Easter, Erse Duderstadt, Vineet Vaibhav, Niveda Sundararaman, Dan P Felsenfeld, Thomas F Vogt, Jennifer Van Eyk, Steve Finkbeiner, Julia A Kaye, Ernest Fraenkel, Leslie M Thompson.
      Huntington's Disease (HD) is caused by a CAG repeat expansion in the gene encoding Huntingtin (HTT). While normal HTT function appears impacted by the mutation, the specific pathways unique to CAG repeat expansion versus loss of normal function are unclear. To understand the impact of the CAG repeat expansion, we evaluated biological signatures of HTT knockout (HTT KO) versus those that occur from the CAG repeat expansion by applying multi-omics, live cell imaging, survival analysis and a novel feature- based pipeline to study cortical neurons (eCNs) derived from an isogenic human embryonic stem cell series (RUES2). HTT KO and the CAG repeat expansion influence developmental trajectories of eCNs, with opposing effects on the growth. Network analyses of differentially expressed genes and proteins associated with enriched epigenetic motifs identified subnetworks common to CAG repeat expansion and HTT KO that include neuronal differentiation, cell cycle regulation, and mechanisms related to transcriptional repression and may represent gain-of-function mechanisms that cannot be explained by HTT loss of function alone. A combination of dominant and loss-of-function mechanisms are likely involved in the aberrant neurodevelopmental and neurodegenerative features of HD that can help inform therapeutic strategies.
    Keywords:  Embryonic stem cells; Features; Huntington's disease; Machine learning; Multi-omics; Network analysis; RUES2; Robotic microscopy
    DOI:  https://doi.org/10.1016/j.nbd.2025.106914
  5. eNeuro. 2025 Apr 24. pii: ENEURO.0545-24.2025. [Epub ahead of print]
    Loss of neuronal Imp contributes to seizure behavior through Syndecan function.
    Paula R Roy, Nichole Link.
      Seizures affect a large proportion of the global population and occur due to abnormal neuronal activity in the brain. Unfortunately, widespread genetic and phenotypic heterogeneity contribute to insufficient treatment options. It is critical to identify the genetic underpinnings of how seizures occur to better understand seizure disorders and improve therapeutic development. We used the Drosophila melanogaster model to identify that IGF-II mRNA Binding Protein (Imp) is linked to the onset of this phenotype. Specific reduction of Imp in neurons causes seizures after mechanical stimulation. Importantly, gross motor behavior is unaffected, showing Imp loss does not affect general neuronal activity. Developmental loss of Imp is sufficient to cause seizures in adults, thus Imp-modulated neuron development affects mature neuronal function. Since Imp is an RNA-binding protein, we sought to identify the mRNA target that Imp regulates in neurons to ensure proper neuronal activity after mechanical stress. We find that Imp protein binds Syndecan (Sdc) mRNA, and reduction of Sdc also causes mechanically-induced seizures. Expression of Sdc in Imp deficient neurons rescues seizure defects, showing that Sdc is sufficient to restore normal behavior after mechanical stress. We suggest that Imp protein binds Sdc mRNA in neurons, and this functional interaction is important for normal neuronal biology and animal behavior in a mechanically-induced seizure model. Since Imp and Sdc are conserved, our work highlights a neuronal specific pathway that might contribute to seizure disorder when mutated in humans.Signficance statement Imp is a widely studied RNA-binding protein in neural stem cell function, but surprisingly little is known about how it functions in post-mitotic neurons in any model system. Here, we show that loss of neuronal Imp impairs mature neuronal function. Moreover, since RNA-binding proteins potentially regulate many targets, we provide a specific mechanism that illuminates how Imp could maintain normal neuronal function though downstream target Syndecan Syndecan functions in cell adhesion, growth factor receptor activation, and intercellular signaling. Loss of Imp, and as a result, Syndecan, could cause defects in neuron migration, growth, or synapse morphology which could significantly impact neuronal function. On a broader level, our work highlights an important pathway to investigate in human brain development and disease.
    DOI:  https://doi.org/10.1523/ENEURO.0545-24.2025
  6. J Cell Biol. 2025 Jun 02. pii: e202412055. [Epub ahead of print]224(6):
    Lysosomal TPC2 channels disrupt Ca2+ entry and dopaminergic function in models of LRRK2-Parkinson's disease.
    Martina Gregori, Gustavo J S Pereira, Robert Allen, Nicholas West, Kai-Yin Chau, Xinjiang Cai, Matthew P Bostock, Stephen R Bolsover, Marco Keller, Chiao-Yin Lee, Si Hang Lei, Kirsten Harvey, Franz Bracher, Christian Grimm, Gaiti Hasan, Matthew E Gegg, Anthony H V Schapira, Sean T Sweeney, Sandip Patel.
      Parkinson's disease results from degeneration of dopaminergic neurons in the midbrain, but the underlying mechanisms are unclear. Here, we identify novel crosstalk between depolarization-induced entry of Ca2+ and lysosomal cation release in maintaining dopaminergic neuronal function. The common disease-causing G2019S mutation in LRRK2 selectively exaggerated Ca2+ entry in vitro. Chemical and molecular strategies inhibiting the lysosomal ion channel TPC2 reversed this. Using Drosophila, which lack TPCs, we show that the expression of human TPC2 phenocopied LRRK2 G2019S in perturbing dopaminergic-dependent vision and movement in vivo. Mechanistically, dysfunction required an intact pore, correct subcellular targeting and Rab interactivity of TPC2. Reducing Ca2+ permeability with a novel biased TPC2 agonist corrected deviant Ca2+ entry and behavioral defects. Thus, both inhibition and select activation of TPC2 are beneficial. Functional coupling between lysosomal cation release and Ca2+ influx emerges as a potential druggable node in Parkinson's disease.
    DOI:  https://doi.org/10.1083/jcb.202412055
  7. Mol Neurobiol. 2025 Apr 20.
    Spinal Cord Organoids from Human Amniotic Fluid iPSC Recapitulate the Diversity of Cell Phenotypes During Fetal Neural Tube Morphogenesis.
    Juan C Biancotti, Hannah E Moore, Anne M Sescleifer, Shelby R Sferra, Annalise B Penikis, Jena L Miller, Shaun M Kunisaki.
      Myelomeningocele (MMC) is a severe form of spina bifida associated with substantial neurologic morbidity. In vitro modeling systems of human spinal cord development may help to elucidate the underlying pathophysiology of the MMC spinal cord. To that end, we developed spinal cord organoids (SCO), defined as self-organized, three-dimensional clusters of spinal tissue, that were derived from human amniotic fluid-induced pluripotent stem cells. Here, we used a variety of analyses, including immunofluorescent and single-cell transcriptomic approaches, to characterize SCOs from healthy and MMC fetuses. Organoids contained a diverse range of neural and mesodermal phenotypes when cultured for up to 130 days in vitro. Multielectrode arrays revealed functional activity with evidence of emerging neuronal networks. Fetal spina bifida environment modeling was successfully established by culturing SCOs in second- and third-trimester amniotic fluid for 3 weeks. Taken together, we show that functional SCOs can recapitulate the cellular identity of the fetal spinal cord and represent a novel research platform to study the interplay between cellular, biochemical, and mechanical cues during human MMC neural tube morphogenesis.
    Keywords:  Amniotic fluid; Fetus; Induced pluripotent stem cells; Myelomeningocele; Organoids; Spinal cord
    DOI:  https://doi.org/10.1007/s12035-025-04944-z
  8. J Transl Med. 2025 Apr 24. 23(1): 471
    OPA1 mutations in dominant optic atrophy: domain-specific defects in mitochondrial fusion and apoptotic regulation.
    Kexuan Zhang, Wenqing Zhang, Lin Zhang, Xiaorong Hou, Runyi Tian, Zhengmao Hu, Lili Yin, Zhonghua Hu.
       BACKGROUND: Autosomal dominant optic atrophy (ADOA), a leading common inherited optic neuropathy, arises from progressive retinal ganglion cell degeneration, often linked to OPA1 mutations. OPA1, a mitochondrial GTPase, regulates mitochondrial fusion, crista structure, and apoptosis. While GTPase-related dysfunction is well-studied, the role of other OPA1 domains in ADOA pathology remains unclear.
    METHODS: To investigate ADOA-linked OPA1 mutations, we assessed mitochondrial morphology, membrane potential, cytochrome c release, and cell viability in primary cortical neurons and N2a cells expressing OPA1 wild-type or mutant constructs. RNA sequencing and structural predictions (SWISS-MODEL) provided insights into molecular pathways and structural impacts.
    RESULTS: Two ADOA-associated mutations were characterized: V465F (GTPase β-fold) and V560F (BSE α-helix). Both mutations impaired mitochondrial fusion and cell survival under apoptotic stimuli. Notably, the BSE-located V560F mutation caused greater deficits in membrane potential maintenance, earlier apoptosis, and distinct molecular pathway changes compared to V465F.
    CONCLUSIONS: This study highlights the domain-specific impacts of OPA1 mutations on mitochondrial function and ADOA pathology, revealing unique roles of the BSE domain in apoptosis regulation and mitochondrial integrity. These findings provide insights into ADOA mechanisms and potential therapeutic targets.
    Keywords:  Apoptosis; Autosomal dominant optic atrophy (ADOA); Bundle signaling element (BSE); GTPase activity; Mitochondrial dynamics; OPA1 mutations
    DOI:  https://doi.org/10.1186/s12967-025-06471-w
  9. J Alzheimers Dis. 2025 Apr 23. 13872877251334831
    Generation of human induced pluripotent stem cell-derived cortical neurons expressing the six tau isoforms.
    Houbo Jiang, Zichun Xiao, Komal Saleem, Ping Zhong, Li Li, Gaurav Chhetri, Pei Li, Zhongjiao Jiang, Zhen Yan, Jian Feng.
      BackgroundThe alternative splicing (AS) of MAPT, which encodes Tau, in the adult human brain produces six major isoforms that play critical roles in the pathogenesis of tauopathies including Alzheimer's disease. Previous efforts have failed to differentiate human induced pluripotent stem cells (hiPSCs) to cortical neurons expressing the six isoforms of Tau.ObjectiveWe aim to develop a differentiation method capable of producing the six Tau isoforms in hiPSC-derived cortical neurons.MethodsWe searched for the optimal concentration, duration and treatment window of morphogens in the differentiation of hiPSCs through embryoid bodies (EBs) to dorsal forebrain neuroepithelial cells then to cortical neurons.ResultsThe combined inhibition of WNT, SHH, and SMAD signaling in EBs generated neuroepithelial cells expressing appropriate dorsal forebrain markers, while suppressing ventral, midbrain, and hindbrain genes. Further differentiation in neurogenic and neurotrophic factors produced MAP2+ neurons at day 18. The iPSC-derived neurons expressed markers of all cortical layers and exhibited synapse formation and synaptic physiology. In addition, MAP2+ neurons and mitotic cells expressing radial glial markers formed aggregates that could be dissociated to produce mature neurons with similar properties. Most importantly, the six Tau isoforms were expressed from day 80 in a developmentally regulated manner, modeling the situation in human brains on an accelerated timeline.ConclusionsThis chemically defined differentiation method produces a key hallmark of mature human cortical neurons by expressing the six main splicing isoforms of Tau. It will greatly facilitate disease modeling and therapeutic discovery for many human brain disorders involving cortical neurons.
    Keywords:  Alzheimer's disease; MAPT; XAV939; alternative splicing; cortical neurons; cyclopamine; induced pluripotent stem cells; tau; tauopathies
    DOI:  https://doi.org/10.1177/13872877251334831
  10. Curr Res Toxicol. 2024 ;7 100197
    iPSC-derived and Patient-Derived Organoids: Applications and challenges in scalability and reproducibility as pre-clinical models.
    Elisa Heinzelmann, Francesco Piraino, Mariana Costa, Aline Roch, Maxim Norkin, Virginie Garnier, Krisztian Homicsko, Nathalie Brandenberg.
      Recent advancements in stem cell technology have led to the development of organoids - three-dimensional (3D) cell cultures that closely mimic the structural and functional characteristics of human organs. These organoids represent a significant improvement over traditional two-dimensional (2D) cell cultures by preserving native tissue architecture and cellular interactions critical for physiological relevance. This review provides a comprehensive comparison between two main types of organoids: induced Pluripotent Stem Cell (iPSC)-derived and Adult Stem Cell (ASC)-derived (also known as Patient-Derived Organoids, PDOs). iPSC-derived organoids, derived from reprogrammed cells, exhibit remarkable plasticity, and can model a wide range of tissues and developmental stages. They are particularly valuable for studying early human development, genetic disorders, and complex diseases. However, challenges such as prolonged differentiation protocols and variability in maturation levels remain significant hurdles. In contrast, ASC-derived organoids, generated directly from patient tissues, faithfully recapitulate tissue-specific characteristics and disease phenotypes. This fidelity makes them indispensable for personalized medicine applications, including drug screening, disease modeling, and understanding individualized treatment responses. The review highlights the unique advantages and limitations of each organoid type, emphasizing their roles in advancing biomedical research and drug discovery. It addresses key challenges in organoid technology, such as scalability, reproducibility, and the need for standardized culture protocols. Furthermore, it explores recent innovations in scaffold-guided organoid engineering and the integration of organoids with advanced technologies like artificial intelligence and high-throughput screening. The integration of organoids with cutting-edge technologies holds promise for enhancing their utility in modeling complex human diseases and accelerating drug discovery and development. By providing more physiologically relevant models of human organs, organoid technology is poised to revolutionize biomedical research, offering new insights into disease mechanisms and personalized therapeutic strategies.
    Keywords:  3D cell culture; Induced Pluripotent Stem Cells (iPSCs); Micro Physiological Systems (MPS); Organoids; Patient-Derived Organoids (PDOs); Pre-clinical models
    DOI:  https://doi.org/10.1016/j.crtox.2024.100197
  11. Neuroinformatics. 2025 Apr 24. 23(2): 30
    Semi-automated Analysis of Beading in Degenerating Axons.
    Pretheesh Kumar V C, Pramod Pullarkat.
      Axonal beading is a key morphological indicator of axonal degeneration, which plays a significant role in various neurodegenerative diseases and drug-induced neuropathies. Quantification of axonal susceptibility to beading using neuronal cell culture can be used as a facile assay to evaluate induced degenerative conditions, and thus aid in understanding mechanisms of beading and in drug development. Manual analysis of axonal beading for large datasets is labor-intensive and prone to subjectivity, limiting the reproducibility of results. To address these challenges, we developed a semi-automated Python-based tool to track axonal beading in time-lapse microscopy images. The software significantly reduces human effort by detecting the onset of axonal swelling. Our method is based on classical image processing techniques rather than an AI approach. This provides interpretable results while allowing the extraction of additional quantitative data, such as bead density, coarsening dynamics, and morphological changes over time. Comparison of results obtained through human analysis and the software shows strong agreement. The code can be easily extended to analyze diameter information of ridge-like structures in branched networks of rivers, road networks, blood vessels, etc.
    Keywords:  Axonal beading; Axonal degeneration; Diameter fluctuations of axons; Image processing; Morphological analysis of axons; Neurodegenerative diseases; Time-lapse microscopy
    DOI:  https://doi.org/10.1007/s12021-025-09726-5
  12. Biochemistry (Mosc). 2025 Feb;90(2): 276-288
    Molecular Biomarkers of Neurodegeneration in Amyotrophic Lateral Sclerosis.
    Denis V Shevchuk, Amir I Tukhvatulin, Alina S Dzharullaeva, Irina A Berdalina, Maria N Zakharova.
      Amyotrophic lateral sclerosis (ALS) is the most prevalent motor neuron disease. However, definitive diagnosis could be delayed by up to 12 months due to the lack of specific and sensitive biomarkers for ALS. In our study, conducted for the first time on a large cohort of ALS patients (n = 100) within the Russian population, we assessed key biomarkers of neurodegenerative pathology, including β-amyloids (Aβ40 and Aβ42) and tau proteins (Tau-total and Tau-p181), as well as other pathogenetically relevant, promising biomarkers such as FGF-21, Kallikrein-6 (KLK-6), NCAM-1, Neurogranin (NRGN), TDP-43, Apolipoprotein E4, Clusterin (Apo J), Complement Factor H, Fetuin-A, α2-Macroglobulin, Apo AI, Apo CIII, Apo E, Complement C3, GDNF, sRAGE, and S100B protein. Significant differences between the ALS patients and the control group were observed for Aβ40 (p = 0.044), Aβ42 (p < 0.001), FGF-21 (p < 0.001), Tau-total (p = 0.001), Tau-p181 (p = 0.014), Clusterin (p < 0.001), Complement C3 (p = 0.001), and S100B (p = 0.024). A significant direct correlation was found between the ALSFRS-R score and concentrations of Aβ40 and Aβ42. Changes in the complement system (Complement C3 and Complement Factor H) were identified, highlighting critical role of neuroinflammatory processes in ALS pathogenesis. Additionally, increased levels of FGF-21 were observed in the patients with the bulbar onset of ALS. Significant increase in the concentration of the chaperone protein clusterin in the patients with rapid disease progression suggests its potential as a prognostic biomarker for motor neuron disease. Furthermore, its role in maintaining proteostasis could provide novel therapeutic targets.
    Keywords:  FGF-21; amyotrophic lateral sclerosis; biomarkers; clusterin; complement factor H; complement C3; tau protein; β-amyloid
    DOI:  https://doi.org/10.1134/S0006297924604039
  13. PLoS Biol. 2025 Apr 21. 23(4): e3003139
    Polarized subcellular activation of Rho proteins by specific ROPGEFs drives pollen germination in Arabidopsis thaliana.
    Alida Melissa Bouatta, Franziska Anzenberger, Lisa Riederauer, Andrea Lepper, Philipp Denninger.
      During plant fertilization, excess male gametes compete for a limited number of female gametes. The dormant male gametophyte, encapsulated in the pollen grain, consists of two sperm cells enclosed in a vegetative cell. After reaching the stigma of a compatible flower, quick and efficient germination of the vegetative cell to a tip-growing pollen tube is crucial to ensure fertilization success. Rho of Plants (ROP) signaling and their activating ROP Guanine Nucleotide Exchange Factors (ROPGEFs) are essential for initiating polar growth processes in multiple cell types. However, which ROPGEFs activate pollen germination is unknown. We investigated the role of ROPGEFs in initiating pollen germination and the required cell polarity establishment. Of the five pollen-expressed ROPGEFs, we found that GEF8, GEF9, and GEF12 are required for pollen germination and male fertilization success, as gef8;gef9;gef12 triple mutants showed almost complete loss of pollen germination in vitro and had a reduced allele transmission rate. Live-cell imaging and spatiotemporal analysis of subcellular protein distribution showed that GEF8, GEF9, and GEF11, but not GEF12, displayed transient polar protein accumulations at the future site of pollen germination minutes before pollen germination, demonstrating specific roles for GEF8 and GEF9 during the initiation of pollen germination. Furthermore, this novel GEF accumulation appears in a biphasic temporal manner and can shift its location laterally. We showed that the C-terminal domain of GEF8 and GEF9 confers their protein accumulation and demonstrated that GEFs locally activate ROPs and alter Ca2+ levels, which is required for pollen tube germination. We demonstrated that not all GEFs act redundantly during pollen germination, and we described for the first time a polar domain with spatiotemporal flexibility, which is crucial for the de novo establishment of a polar growth domain within a cell and, thus, for pollen function and fertilization success.
    DOI:  https://doi.org/10.1371/journal.pbio.3003139
  14. Proc Natl Acad Sci U S A. 2025 Apr 29. 122(17): e2502971122
    Rab32 regulates Golgi structure and cell migration through Protein Kinase A-mediated phosphorylation of Optineurin.
    Katherine M Johnson, Maxwell G Marley, Kristina Drizyte-Miller, Jing Chen, Hong Cao, Nourhan Mostafa, Micah B Schott, Mark A McNiven, Gina L Razidlo.
      Rab32 is a small GTPase and molecular switch implicated in vesicular trafficking. Rab32 is also an A-Kinase Anchoring Protein (AKAP), which anchors cAMP-dependent Protein Kinase (PKA) to specific subcellular locations and specifies PKA phosphorylation of nearby substrates. Surprisingly, we found that a form of Rab32 deficient in PKA binding (Rab32 L188P) relocalized away from the Golgi apparatus and induced a marked disruption in Golgi organization, assembly, and dynamics. Although Rab32 L188P did not cause a global defect in PKA activity, our data indicate that Rab32 facilitates the phosphorylation of a specific PKA substrate. We uncovered a direct interaction between Rab32 and the adaptor protein optineurin (OPTN), which regulates Golgi dynamics. Further, our data indicate that optineurin is phosphorylated by PKA at Ser342 in a Rab32-dependent manner. Critically, blocking phosphorylation at OPTN Ser342 leads to Golgi fragmentation, and a phospho-mimetic version of OPTN rescues Golgi defects induced by Rab32 L188P. Finally, Rab32 AKAP function and OPTN phosphorylation are required for Golgi repositioning during cell migration, contributing to tumor cell invasion. Together, these data reveal a role for Rab32 in regulating Golgi dynamics through PKA-mediated phosphorylation of OPTN.
    Keywords:  Golgi; Optineurin; Protein Kinase A; Rab32; migration
    DOI:  https://doi.org/10.1073/pnas.2502971122
  15. J Cell Mol Med. 2025 Apr;29(8): e70455
    Pathogenetic Involvement of Autophagy and Mitophagy in Primary Progressive Multiple Sclerosis.
    Simone Patergnani, Michele Laudisi, Massimo Bonora, Giulio Righes, Sofia Straudi, Mariusz R Wieckowski, Ilaria Casetta, Luana Semenzato, Konstantinos Koutsikos, Veronica Zanato, Carlotta Giorgi, Paolo Pinton.
      Primary progressive multiple sclerosis (PPMS) affects a subset of MS patients and is characterised by continuous progression from the onset. The molecular mechanisms underlying PPMS are poorly understood, and therapeutic options are limited, with no specific markers for early detection and monitoring. This study investigated the roles of autophagy and mitophagy in PPMS. We found that autophagy markers (ATG5 and ATG7) and mitophagy markers (Parkin and Optineurin) were significantly reduced in the serum of PPMS patients compared to control and relapsing-remitting MS (RRMS) individuals. This reduction was associated with an increase in markers indicative of neurodegeneration and mitochondrial dysfunction. Additionally, a positive correlation between autophagy and mitophagy proteins in the PPMS group suggests that these mechanisms are reciprocally associated and modulated in PPMS. Our investigation reveals that autophagy and mitophagy are actively involved in PPMS and exhibit distinct patterns across MS subtypes. Measurements of circulating components related to autophagy and mitophagy could serve as potential biomarkers for early PPMS detection.
    Keywords:  ATG5; ATG7; GFAP; Optineurin; Parkin; biomarker; lactate; serum
    DOI:  https://doi.org/10.1111/jcmm.70455
  16. Hum Mol Genet. 2025 Apr 23. pii: ddaf052. [Epub ahead of print]
    Kinetin mediated mutant huntingtin phosphorylation restores multiple dysregulated pathways in a cell line model of Huntington's disease.
    Rajubhai Dabhi, Ragi Mehta, Dhruvi Kakadiya, Ravi Vijayvargia.
      Huntington's disease (HD) is a fatal neurodegenerative disease caused by CAG trinucleotide repeat expansion in the huntingtin gene (Htt) resulting in an expanded polyglutamine (polyQ) tract in the huntingtin (HTT) protein. The expanded polyQ alters structure of HTT making it susceptible to aggregation. The expression of mutant HTT (mHTT) causes dysregulation of several key cellular pathways in neuronal cells resulting in neurodegeneration. Recent studies have demonstrated phosphorylation of the N-terminal domain of the huntingtin (N-HTT) protein as an important regulator of its localization, structure, aggregation, clearance and toxicity. Most studies have focused on the effect of phosphorylation of Ser13 and Ser16 in N-HTT on protein aggregation and reported a drastic reduction in aggregation. However, the downstream impact of this phosphorylation status on key cellular pathways is largely unexplored. Utilizing an inducible cell line model for expression of Exon 1 fragment of mHTT bearing 150 polyglutamine repeats (HD150Q), we demonstrate that kinetin induced phosphorylation at Ser13 and Ser16 of N-HTT resulted in prevention of aggregation as well as resolution of preformed aggregates. Furthermore, kinetin treatment led to rescue of ATP levels and transcription of key genes as well as significant reduction in mitochondrial ROS levels restoring mitochondrial function. Notably, ER stress markers were significantly reduced at transcriptional, translational and post-translational levels. Restoration of mitochondrial function and mitigation of ER stress lead to significant improvement in cell survival. These findings further strengthen the view that HTT N-terminal phosphorylation is a promising therapeutic target for HD.
    Keywords:  Huntingtin phosphorylation; Huntington’s disease; Kinetin; Mutant huntingtin
    DOI:  https://doi.org/10.1093/hmg/ddaf052
  17. Aging Brain. 2025 ;7 100136
    Tau aggregation induces cell death in iPSC-derived neurons.
    Hirokazu Tanabe, Sumihiro Maeda, Etsuko Sano, Norio Sakai, Setsu Endoh-Yamagami, Hideyuki Okano.
      Abnormal accumulation of tau proteins in the brain is a hallmark of neurodegenerative diseases such as Alzheimer's disease and is closely linked with neuronal cell death. Tau accumulation is a prominent therapeutic target for Alzheimer's disease, since tau accumulation correlates well with the disease progression, and tau-targeting drugs hold potentials to halt the disease progression. Given the differential response of human and mouse neuronal cells, there is a critical need for a human cellular platform to quickly screen for tau-related neurodegenerative disease therapeutics. However, inducing rapid, tau-dependent neuronal cell death in human models remains challenging. In this study, we established a human cellular model capable of inducing tau aggregation-dependent neuronal cell death within two weeks via tau overexpression. Additionally, we demonstrated the neuroprotective efficacy of known tau-targeting compounds within this system. These findings suggest that our cellular model recapitulates the molecular pathogenesis of tau-induced neurodegeneration and could serve as a valuable platform for drug screening in tauopathies.
    Keywords:  Aggregation; Neuronal cell death; Overexpression; Tau; iPSC
    DOI:  https://doi.org/10.1016/j.nbas.2025.100136
  18. J Cell Biol. 2025 May 05. pii: e202503004. [Epub ahead of print]224(5):
    TMBIM-2 links neuronal mitochondrial stress to systemic adaptation via calcium signaling.
    Yu Sun, Terytty Yang Li.
      Mitochondrial function is critical for neuronal activity and systemic metabolic adaptation. In this issue, Li et al. (https://doi.org/10.1083/jcb.202408050) identify TMBIM-2 as a key regulator of calcium dynamics, coordinating the neuronal-to-intestinal mitochondrial unfolded protein response (UPRmt), pathogen-induced aversive learning, and aging.
    DOI:  https://doi.org/10.1083/jcb.202503004
  19. Biochem Biophys Res Commun. 2025 Apr 16. pii: S0006-291X(25)00543-1. [Epub ahead of print]765 151829
    Mitochondrial calpain-1 truncates ATP synthase beta subunit.
    Yusaku Chukai, Nanami Furukawa, On Kosegawa, Lanlan Bai, Eriko Sugano, Tomokazu Fukuda, Hiroshi Tomita, Taku Ozaki.
      Calpains cleave proteins in a calcium concentration-dependent manner, modulating their intracellular functions. Calpain-1, a member of the calpain family, is localized in the cytosol and mitochondria. Mitochondrial calpain-1 induces mitochondrial dysfunction and apoptosis by cleaving its substrate. Thus, identifying the substrate of calpain-1 is essential to understand its function. However, little is known about the substrates of mitochondrial calpain-1. To address this issue, we screened mitochondrial proteins using bioinformatics approaches and two-dimensional gel electrophoresis. We identified ATP5B as a potential substrate of mitochondrial calpain-1. Calpeptin, a pan-calpain inhibitor, and Tat-μCL, a mitochondrial calpain-1 specific inhibitor, prevented the truncation of ATP5B during in vitro Ca2+ incubation. Using recombinant human calpain-1 and ATP5B proteins, we demonstrated that calpain-1 directly cleaved ATP5B, generating a fragment of ATP5B. Based on the predicted cleavage sites in ATP5B, this cleavage may disrupt its interaction with ATP5A1, leading to mitochondrial dysfunction in ATP production. This study identified ATP5B as a novel substrate of mitochondrial calpain-1. The results provide new insights into mitochondrial dysfunction.
    Keywords:  ATP5B; Calpain-1; Mitochondria
    DOI:  https://doi.org/10.1016/j.bbrc.2025.151829
  20. PLoS Genet. 2025 Apr 25. 21(4): e1011678
    Mitochondrial fission surveillance is coupled to Caenorhabditis elegans DNA and chromosome segregation integrity.
    Xiaomeng Yang, Ruichen Wei, Fanfan Meng, Dianchen Liu, Xuan Gong, Gary Ruvkun, Wei Wei.
      Mitochondrial fission and fusion are tightly regulated to specify mitochondrial abundance, localization, and arrangement during cell division as well as in the diverse differentiated cell types and physiological states. However, the regulatory pathways for such mitochondrial dynamics are less explored than the mitochondrial fission and fusion components. Here we report a large-scale screen for genes that regulate mitochondrial fission. Mitochondrial fission defects cause a characteristic uneven fluorescent pattern in embryos carrying mitochondrial stress reporter genes. Using this uneven activation, we performed RNAi screens that identified 3 kinase genes from a ~ 500-kinase library and another 11 genes from 3,300 random genes that function in mitochondrial fission. Many of these identified genes play roles in chromosome segregation. We found that chromosome missegregation and genome instability lead to dysregulation of mitochondrial fission, possibly independent of DRP-1. ATL-1, the C. elegans ATR orthologue, plays a potentially protective role in alleviating the mitochondrial fission defect caused by chromosome missegregation. This establishes a screening paradigm for identifying mitochondrial fission regulators, which reveals the potential role of ATR in surveilling mitochondrial fission to mitigate dysregulation caused by improper chromosome segregation.
    DOI:  https://doi.org/10.1371/journal.pgen.1011678
  21. EMBO J. 2025 Apr 22.
    Autophagosomes anchor an AKAP11-dependent regulatory checkpoint that shapes neuronal PKA signaling.
    Ashley Segura-Roman, Y Rose Citron, Myungsun Shin, Nicole Sindoni, Alex Maya-Romero, Simon Rapp, Claire Goul, Joseph D Mancias, Roberto Zoncu.
      Protein Kinase A (PKA) is regulated spatially and temporally via scaffolding of its catalytic (Cα) and regulatory (RI/RII) subunits by the A-kinase-anchoring proteins (AKAP). By binding to an AKAP11 scaffold, PKA engages in poorly understood interactions with autophagy, a key degradation pathway for neuronal cell homeostasis. Mutations in AKAP11 promote schizophrenia and bipolar disorders (SZ-BP) through unknown mechanisms. Here, through proteomic-based analyses of immunopurified lysosomes, we identify the Cα-RIα-AKAP11 holocomplex as a prominent autophagy-associated protein-kinase complex. AKAP11 scaffolds Cα-RIα interaction with the autophagic machinery via its LC3-interacting region (LIR), enabling both PKA regulation by upstream signals, and its autophagy-dependent degradation. We identify Ser83 on the RIα linker-hinge region as an AKAP11-dependent phospho-residue that modulates RIα-Cα binding to the autophagosome and cAMP-induced PKA activation. Decoupling AKAP11-PKA from autophagy alters downstream phosphorylation events, supporting an autophagy-dependent checkpoint for PKA signaling. Ablating AKAP11 in induced pluripotent stem cell-derived neurons reveals dysregulation of multiple pathways for neuronal homeostasis. Thus, the autophagosome is a platform that modulates PKA signaling, providing a possible mechanistic link to SZ/BP pathophysiology.
    Keywords:  AKAP11; Autophagy; Phosphoproteomics; Protein kinase A; Signaling
    DOI:  https://doi.org/10.1038/s44318-025-00436-x
  22. Curr Biol. 2025 Apr 21. pii: S0960-9822(25)00296-9. [Epub ahead of print]35(8): R287-R290
    Cell biology: Mitochondrial protease degrades unoccupied translocases upon import stress.
    Mohamed A Eldeeb, Michael Shahid, Edward A Fon.
      Dysregulation of mitochondrial protein import induces significant cellular stress. Yet, our understanding of the dialogue between mitochondrial import, the stress it can trigger, and counteracting mechanisms remains incomplete. A recent study unveils how the mitochondrial protease YME1L1 degrades unoccupied mitochondrial translocases during mitochondrial import stress.
    DOI:  https://doi.org/10.1016/j.cub.2025.03.011
  23. Cell Mol Life Sci. 2025 Apr 21. 82(1): 169
    Organoids in disease modeling and regenerative medicine.
    Ryuji Morizane, Mart M Lamers.
      Organoid technology has the potential to revolutionize biomedical research by providing more physiologically relevant models for studying human development, disease mechanisms, and therapeutic development. Derived from stem cells, organoids self-organize into three-dimensional tissues that replicate the structures and functions of their in vivo counterparts. Their ability to mimic organ-specific microstructures offers new tools for investigating organogenesis, modeling genetic disorders, and screening potential therapeutics using human cells. Additionally, organoids hold promise for regenerative medicine as potential transplantable tissues for repairing or replacing damaged organs. However, challenges such as batch variability, standardization, vascularization, long-term viability, and lack of immune cells remain, hindering their clinical translation and use in disease studies. Recent efforts have focused on improving reproducibility, incorporating bioengineering techniques for enhanced maturation, and optimizing differentiation methods. This collection highlights recent advances in the respiratory, renal, and retinal organoid systems. From refining cryopreservation methods to using organoid models for virus neutralization and inflammatory studies, these contributions emphasize the potential of organoids in translational research and regenerative medicine.
    DOI:  https://doi.org/10.1007/s00018-025-05692-y
  24. PLoS Comput Biol. 2025 Apr 21. 21(4): e1013047
    Theory of axo-axonic inhibition.
    Romain Brette.
      The axon initial segment of principal cells of the cortex and hippocampus is contacted by GABAergic interneurons called chandelier cells. The anatomy, as well as alterations in neurological diseases such as epilepsy, suggest that chandelier cells exert an important inhibitory control on action potential initiation. However, their functional role remains unclear, including whether their effect is indeed inhibitory or excitatory. One reason is that there is a relative gap in electrophysiological theory about the electrical effect of axo-axonic synapses. This contribution uses resistive coupling theory, a simplification of cable theory based on the observation that the small initial segment is resistively coupled to the large cell body acting as a current sink, to fill this gap. The main theoretical finding is that a synaptic input at the proximal axon shifts the action potential threshold by an amount equal to the product of synaptic conductance, driving force at threshold, and axial axonal resistance between the soma and either the synapse or of the middle of the initial segment, whichever is closer. The theory produces quantitative estimates useful to interpret experimental observations, and supports the idea that axo-axonic cells can potentially exert powerful inhibitory control on action potential initiation.
    DOI:  https://doi.org/10.1371/journal.pcbi.1013047
  25. J Neurosci Res. 2025 Apr;103(4): e70040
    A Novel Mutation in CNTNAP1 Gene Causes Disorganization of Axonal Domains, Hypomyelination and Severe Neurological Deficits.
    Lacey B Sell, Carson Zabel, Sabine Weller Grønborg, Qian Shi, Manzoor A Bhat.
      CNTNAP1 encodes the contactin-associated protein 1 (Cntnap1) which localizes to the paranodal region in all myelinated axons and is essential for axonal domain organization and the propagation of action potentials. To date, close to 45 reported human CNTNAP1 variants have been identified that are associated with dysregulation and disorganization of the axonal domains, resulting in various forms of congenital hypomyelinating neuropathies in children. Currently, no treatments are available for neuropathies caused by CNTNAP1 variants, highlighting the importance of fully characterizing these mutations and their impact on Cntnap1 functions. To understand the importance of a novel human CNTNAP1 likely pathogenic variant that changes glycine at position 349 to valine in a child who also carries a CNTNAP1 truncation and displayed severe neurological deficits, we used CRISPR/Cas9 methodology and introduced a single nucleotide substitution in the mouse Cntnap1 gene, resulting in glycine at 350 to valine (Cntnap1G350V). Trans-allelic combination of Cntnap1G350V with a Cntnap1 null allele (Cntnap1G350V/-) mimics human pathologies, recapitulating hypomyelination neuropathies associated with CNTNAP1 mutations as well as loss of paranodal junctions and disorganization of axonal domains in myelinated axons. Expression of the wild type Cntnap1 transgene in Cntnap1G350V/- mice rescued the mutant phenotypes and restored all neurological deficits. Our studies demonstrate that GGT (glycine) to GTT (valine) change in human CNTNAP1 creates a recessive loss of function allele and lays the foundation for potential gene therapy studies aimed at treating CNTNAP1-associated hypomyelinating neuropathies in children.
    Keywords:  congenital hypomyelinating neuropathy type 3; human CNTNAP1 variant; hypomyelination; neurological diseases
    DOI:  https://doi.org/10.1002/jnr.70040
  26. Cells. 2025 Apr 21. pii: 619. [Epub ahead of print]14(8):
    Induced Pluripotent Stem Cells-Based Regenerative Therapies in Treating Human Aging-Related Functional Decline and Diseases.
    Peijie Yu, Bin Liu, Cheng Dong, Yun Chang.
      A significant increase in life expectancy worldwide has resulted in a growing aging population, accompanied by a rise in aging-related diseases that pose substantial societal, economic, and medical challenges. This trend has prompted extensive efforts within many scientific and medical communities to develop and enhance therapies aimed at delaying aging processes, mitigating aging-related functional decline, and addressing aging-associated diseases to extend health span. Research in aging biology has focused on unraveling various biochemical and genetic pathways contributing to aging-related changes, including genomic instability, telomere shortening, and cellular senescence. The advent of induced pluripotent stem cells (iPSCs), derived through reprogramming human somatic cells, has revolutionized disease modeling and understanding in humans by addressing the limitations of conventional animal models and primary human cells. iPSCs offer significant advantages over other pluripotent stem cells, such as embryonic stem cells, as they can be obtained without the need for embryo destruction and are not restricted by the availability of healthy donors or patients. These attributes position iPSC technology as a promising avenue for modeling and deciphering mechanisms that underlie aging and associated diseases, as well as for studying drug effects. Moreover, iPSCs exhibit remarkable versatility in differentiating into diverse cell types, making them a promising tool for personalized regenerative therapies aimed at replacing aged or damaged cells with healthy, functional equivalents. This review explores the breadth of research in iPSC-based regenerative therapies and their potential applications in addressing a spectrum of aging-related conditions.
    Keywords:  aging-related diseases; cellular reprogramming; induced pluripotent stem cells; personalized therapies; regenerative medicine
    DOI:  https://doi.org/10.3390/cells14080619
  27. Lancet Neurol. 2025 May;pii: S1474-4422(25)00117-6. [Epub ahead of print]24(5): 380-381
    The four most common genetic subtypes of amyotrophic lateral sclerosis: state of the art and future directions.
    Pamela Shaw Dame.
      
    DOI:  https://doi.org/10.1016/S1474-4422(25)00117-6
  28. Hum Cell. 2025 Apr 23. 38(3): 95
    Generation of human induced pluripotent stem cell lines derived from a patient carrying an intragenic deletion in the NFIA gene.
    Ning Zhou, Shengnan Zhang, Chunli Wang, Bixia Zheng, Aihua Zhang, Wei Zhou.
      Brain malformations with or without urinary tract defects (BRMUTD) are caused by heterozygous variants in the NFIA gene. BRMUTD is a neurodevelopmental disorder characterized by hypoplasia or absence of the corpus callosum, hydrocephalus or ventriculomegaly, and developmental delay, which may or may not be accompanied by urinary tract defects. Here, we report the successful generation of induced pluripotent stem cells (hiPSCs) from a 3-year-old male BRMUTD patient using Sendai virus-based non-integrating reprogramming technology. This patient-derived cell line harbors an intragenic deletion within the NFIA gene (NC_000001.10: g.61650967_61842967del [GRCh37]), which is associated with a significant reduction in NFIA expression. This cell line maintains a normal karyotype, expresses pluripotency markers, and can differentiate into three germ layers. The established hiPSCs line will provide an in vitro model for studying pathological mechanisms and potential therapies of NFIA-related neurodevelopmental disorder.
    Keywords:   NFIA variant; BRMUTD; Brain malformations with or without urinary tract defects; Neurodevelopmental disorder; hiPSCs
    DOI:  https://doi.org/10.1007/s13577-025-01222-x
  29. Annu Rev Phys Chem. 2025 Apr;76(1): 103-128
    Resolving Conformational Plasticity in Mammalian Cells with High-Resolution Fluorescence Tools.
    Hao Ruan, Edward A Lemke.
      Investigating protein dynamic structural changes is fundamental for understanding protein function, drug discovery, and disease mechanisms. Traditional studies of protein dynamics often rely on investigations of purified systems, which fail to capture the complexity of the cellular environment. The intracellular milieu imposes distinct physicochemical constraints that affect macromolecular interactions and dynamics in ways not easily replicated in isolated experimental setups. We discuss the use of fluorescence resonance energy transfer, fluorescence anisotropy, and minimal photon flux imaging technologies to address these challenges and directly investigate protein conformational dynamics in mammalian cells. Key findings from the application of these techniques demonstrate their potential to reveal intricate details of protein conformational plasticity. By overcoming the limitations of traditional in vitro methods, these approaches offer a more accurate and comprehensive understanding of protein function and behavior within the complex environment of mammalian cells.
    Keywords:  MINFLUX; anisotropy; fluorescence lifetime; genetic code expansion; in situ conformational plasticity; single-molecule FRET
    DOI:  https://doi.org/10.1146/annurev-physchem-082423-030632
  30. Front Cell Neurosci. 2025 ;19 1560402
    Activity-dependent refinement of axonal projections forms one-to-one connection pattern in the developing chick ciliary ganglion.
    Ryo Egawa, Hiromu Yawo, Hiroshi Kuba.
      Although it is well established that initially overproduced synaptic connections are extensively remodeled through activity-dependent competition for postsynaptic innervation, the mechanisms determining the final number of postsynaptic targets per axon remain unclear. Here, we investigated the morphology of individual axonal projections during development and the influence of neural activity in the chick ciliary ganglion (CG), a traditional model system for synapse maturation. By single-axon tracing combining Brainbow labeling and tissue clearing, we revealed that by embryonic day 14 (E14), hundreds of preganglionic axons each establish a one-to-one synaptic connection with single CG neurons via a calyx-type presynaptic terminal enveloping the soma of its postsynaptic target. This homogeneous connection pattern emerged through presynaptic terminal maturation from bouton-like to calyx-like morphology and concurrent axonal branch pruning starting around E10. The calyx maturation was retarded by the presynaptic expression of genetically encoded tools for silencing neuronal activity, enhanced tetanus neurotoxin light chain (eTeNT) or Kir2.1, demonstrating the activity-dependence of this morphological refinement. These findings suggest that some presynaptic mechanisms as well as synaptic competition would operate to restrict the number of postsynaptic targets innervated by each axon in the CG. Together with the easy accessibility to single-axon tracing, our results highlight the potential of the chick CG as a model for investigating the presynaptic factors underlying circuit remodeling.
    Keywords:  Brainbow labeling; axon pruning; calyx synapse; in ovo electroporation; single-axon tracing; synaptic competition; tissue clearing
    DOI:  https://doi.org/10.3389/fncel.2025.1560402
  31. Biomark Res. 2025 Apr 21. 13(1): 63
    Challenges and advances for huntingtin detection in cerebrospinal fluid: in support of relative quantification.
    Rachel J Harding, Yuanyun Xie, Nicholas S Caron, Hailey Findlay-Black, Caroline Lyu, Nalini Potluri, Renu Chandrasekaran, Michael R Hayden, Blair R Leavitt, Douglas R Langbehn, Amber L Southwell.
      Huntington disease (HD) is a progressive and devastating neurodegenerative disease caused by expansion of a glutamine-coding CAG tract in the huntingtin (HTT) gene above a critical threshold of ~ 35 repeats resulting in expression of mutant HTT (mHTT). A promising treatment approach being tested in clinical trials is HTT lowering, which aims to reduce levels of the mHTT protein. Target engagement of these therapies in the brain are inferred using antibody-based assays that measure mHTT levels in the cerebrospinal fluid (CSF). These levels are typically reported as the absolute concentration of mHTT concentration, derived from a standard curve generated using a single protein standard. However, patient biofluids are a complex milieu containing different mHTT protein species, suggesting that absolute quantitation is challenging. As a result, a single recombinant protein standard may not be sufficient to interpret assay signal as molar mHTT concentration. In this study, we used immunoprecipitation and flow cytometry (IP-FCM) to investigate different factors that influence mHTT detection assay signal. Our results show that HTT protein fragmentation, protein-protein interactions, affinity tag positioning, oligomerization and polyglutamine tract length affect assay signal intensity. These findings indicate that absolute HTT quantitation in heterogeneous biological samples is not possible with current technologies using a single standard protein. We also explore the binding specificity of the MW1 anti-polyglutamine antibody, commonly used in these assays as a mHTT-selective reagent and demonstrate that mHTT binding is preferred but not specific. Furthermore, we find that MW1 depletion of mHTT for quantitation of wildtype HTT is not only incomplete, leaving residual mHTT, but also non-specific, resulting in pull down of some wildtype HTT protein. Based on these observations, we recommend that mHTT detection assays report only relative mHTT quantitation using normalized arbitrary units of assay signal intensity, rather than molar concentrations, in the assessment of central nervous system HTT lowering in ongoing clinical and preclinical studies. Further, we recommend that MW1-depletion not be used as a method for quantifying wildtype HTT protein and that detergent be consistently added to samples during testing.
    Keywords:  Biomarkers; Huntingtin Detection; Huntingtin Lowering Therapies; Huntington’s Disease
    DOI:  https://doi.org/10.1186/s40364-025-00772-4
  32. Mol Neurodegener. 2025 Apr 23. 20(1): 45
    Increased TMEM106B levels lead to lysosomal dysfunction which affects synaptic signaling and neuronal health.
    Jolien Perneel, Miranda Lastra Osua, Sara Alidadiani, Nele Peeters, Linus De Witte, Bavo Heeman, Simona Manzella, Riet De Rycke, Mieu Brooks, Ralph B Perkerson, Elke Calus, Wouter De Coster, Manuela Neumann, Ian R A Mackenzie, Debby Van Dam, Bob Asselbergh, Tommas Ellender, Xiaolai Zhou, Rosa Rademakers.
       BACKGROUND: Genetic variation in Transmembrane protein 106B (TMEM106B) is known to influence the risk and presentation in several neurodegenerative diseases and modifies healthy aging. While evidence from human studies suggests that the risk allele is associated with higher levels of TMEM106B, the contribution of elevated levels of TMEM106B to neurodegeneration and aging has not been assessed and it remains unclear how TMEM106B modulates disease risk.
    METHODS: To study the effect of increased TMEM106B levels, we generated Cre-inducible transgenic mice expressing human wild-type TMEM106B. We evaluated lysosomal and neuronal health using in vitro and in vivo assays including transmission electron microscopy, immunostainings, behavioral testing, electrophysiology, and bulk RNA sequencing.
    RESULTS: We created the first transgenic mouse model that successfully overexpresses TMEM106B, with a 4- to 8-fold increase in TMEM106B protein levels in heterozygous (hTMEM106B(+)) and homozygous (hTMEM106B(++)) animals, respectively. We showed that the increase in TMEM106B protein levels induced lysosomal dysfunction and age-related downregulation of genes associated with neuronal plasticity, learning, and memory. Increased TMEM106B levels led to altered synaptic signaling in 12-month-old animals which further exhibited an anxiety-like phenotype. Finally, we observed mild neuronal loss in the hippocampus of 21-month-old animals.
    CONCLUSION: Characterization of the first transgenic mouse model that overexpresses TMEM106B suggests that higher levels of TMEM106B negatively impacts brain health by modifying brain aging and impairing the resilience of the brain to the pathomechanisms of neurodegenerative disorders. This novel model will be a valuable tool to study the involvement and contribution of increased TMEM106B levels to aging and will be essential to study the many age-related diseases in which TMEM106B was genetically shown to be a disease- and risk-modifier.
    Keywords:  Lysosomal dysfunction; Mouse model; Neuronal activity; Synaptic signaling; TMEM106B
    DOI:  https://doi.org/10.1186/s13024-025-00831-2
  33. Proc Natl Acad Sci U S A. 2025 Apr 29. 122(17): e2413651122
    Neuronal autophagy controls excitability via ryanodine receptor-mediated regulation of calcium-activated potassium channel function.
    Gaga Kochlamazashvili, Aarti Swaminathan, Alexander Stumpf, Amit Kumar, York Posor, Dietmar Schmitz, Volker Haucke, Marijn Kuijpers.
      Glutamate-mediated neuronal hyperexcitation plays a causative role in eliciting seizures and promoting epileptogenesis. Recent data suggest that altered autophagy can contribute to the occurrence of epilepsy. We examined the role of autophagy in neuronal physiology by generating knockout mice conditionally lacking the essential autophagy protein ATG5 in glutamatergic neurons. We demonstrate that conditional genetic blockade of neuronal autophagy results in action potential narrowing, axonal hyperexcitability, and an increase in kainate-induced epileptiform bursts ex vivo, indicative of a lower threshold for the induction of epileptic seizures. Neuronal hyperexcitability in hippocampal slices from conditional ATG5 knockout mice is due to elevated activity of the large conductance calcium-activated potassium channel BKCa downstream of calcium influx via the endoplasmic reticulum (ER)-localized calcium channel ryanodine receptor (RYR). Consistently, pharmacological blockade of RYR or BKCa function rescued hyperexcitability and reduced the frequency of kainate-induced epileptiform bursts in ATG5 cKO brain slices. Our findings reveal a physiological role for neuronal autophagy in the regulation of neuronal excitability via the control of RYR-mediated calcium release, and thereby, calcium-activated potassium channel function in the mammalian brain.
    Keywords:  action potential; autophagy; neuronal excitability; potassium channel; ryanodine receptor
    DOI:  https://doi.org/10.1073/pnas.2413651122
  34. Neurosci Bull. 2025 Apr 22.
    Neural Responses to Hypoxic Injury in a Vascularized Cerebral Organoid Model.
    Yang Li, Xin-Yao Sun, Peng-Ming Zeng, Zhen-Ge Luo.
      Hypoxic injury (HI) in the prenatal period often causes neonatal neurological disabilities. Due to the difficulty in obtaining clinical samples, the molecular and cellular mechanisms remain unclear. Here we use vascularized cerebral organoids to investigate the hypoxic injury phenotype and explore the intercellular interactions between vascular and neural tissues under hypoxic conditions. Our results indicate that fused vascularized cerebral organoids exhibit broader hypoxic responses and larger decreases in panels of neural development-related genes when exposed to low oxygen levels compared to single cerebral organoids. Interestingly, vessels also exhibit neural protective effects on T-box brain protein 2+ intermediate progenitors (IPs), which are markedly lost in HI cerebral organoids. Furthermore, we identify the role of bone morphogenic protein signaling in protecting IPs. Thus, this study has established an in vitro organoid system that can be used to study the contribution of vessels to brain injury under hypoxic conditions and provides a strategy for the identification of intervention targets.
    Keywords:  BMP signaling; Cerebral organoid; Hypoxia; Hypoxic-injury encephalopathy; Vascularized cerebral organoid
    DOI:  https://doi.org/10.1007/s12264-025-01396-2
  35. J Mol Neurosci. 2025 Apr 24. 75(2): 54
    UCHL1-Mediated Spastin Degradation Regulates Microtubule Severing and Hippocampal Neurite Outgrowth.
    Ao Ma, Zhi Liang, Hongde Zhang, Zhichao Meng, Jiehao Zhu, Shu Chen, Qisheng Lin, Tao Jiang, Minghui Tan.
      As a key component of the cytoskeleton, microtubule dynamic provides structural support for neurite outgrowth. Spastin, a microtubule severing enzyme associated with hereditary spastic paraplegia (HSP), is crucial for the growth and branching of neuronal processes. Thus, the activity and function of spastin need to be strictly regulated. However, the mechanism by which spastin protein levels are regulated is still poorly understood. In the current study, we showed that UCHL1 interacted with spastin via mass spectrometry, GST-pulldown and immunoprecipitation assays. Overexpression of UCHL1 decreased the protein level of spastin, while the genetic knockdown of UCHL1 increased that of spastin. CHX chase assay showed that UCHL1 regulated the protein degradation of spastin. Application of proteasome inhibitor MG-132 suppressed UCHL1-mediated spastin degradation. Furthermore, overexpression or knockout of UCHL1 can inhibit or restore spastin-mediated microtubule severing, thereby regulating neuronal length and branch formation. These findings reveal the important regulatory mechanism of UCHL1 on spastin-mediated neurite outgrowth.
    Keywords:  Microtubule severing; Neurite outgrowth; Protein degradation; Spastin; UCHL1
    DOI:  https://doi.org/10.1007/s12031-025-02348-1
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