bims-axbals Biomed News
on Axonal biology and ALS
Issue of 2025–03–30
twenty-six papers selected by
TJ Krzystek
  1. C9ORF72 poly-PR disrupts expression of ALS/FTD-implicated STMN2 through SRSF7.
  2. Electrophysiological characterization of sourced human iPSC-derived motor neurons.
  3. Microglia in ALS: Insights into Mechanisms and Therapeutic Potential.
  4. Optineurin knock-out forms TDP-43 aggregates to regulate TDP-43 protein levels despite autophagic up-regulation and aberrant TDP-43 expression.
  5. A Twist in Yeast: New Perspectives for Studying TDP-43 Proteinopathies in S. cerevisiae.
  6. Neurodegenerative and Neurodevelopmental Roles for Bulk Lipid Transporters VPS13A and BLTP2.
  7. Proteostasis and lysosomal repair deficits in transdifferentiated neurons of Alzheimer's disease.
  8. The Balance of MFN2 and OPA1 in Mitochondrial Dynamics, Cellular Homeostasis, and Disease.
  9. Non-muscle myosin II inhibition at the site of axon injury increases axon regeneration.
  10. Patient-specific mutation of a contact site protein Tomm70 causes neurodegeneration in a zebrafish model.
  11. Cell biology: A new dynamin superfamily protein remodels mitochondrial dynamics.
  12. Fluid-based biomarkers for neurodegenerative diseases.
  13. Targeted degradation of α-Synuclein using an evolved botulinum toxin protease.
  14. Uncontrolled CAG expansion in neurons susceptible to Huntington's disease.
  15. S-palmitoylation modulates ATG2-dependent non-vesicular lipid transport during starvation-induced autophagy.
  16. Ameliorating TIMM50 Loss Slows Senescence by Improving Mitochondrial Structure and Function.
  17. R406 and its structural analogs reduce SNCA/α-synuclein levels via autophagic degradation.
  18. Transgenic iPSC Lines with Genetically Encoded MitoTimer to Study Mitochondrial Biogenesis in Dopaminergic Neurons with Tauopathy.
  19. Therapeutic Efficacy of Small Extracellular Vesicles Loaded with ROCK Inhibitor in Parkinson's Disease.
  20. Human Retinal Organoid Model of Ocular Toxoplasmosis.
  21. In situ architecture of the human prohibitin complex.
  22. Dependence of mitochondrial calcium signalling and dynamics on the disaggregase, CLPB.
  23. Monitoring Autophagy in Human Aging: Key Cell Models and Insights.
  24. Secretory autophagy in neurons: more than throwing out the trash?
  25. In Vitro Modeling of Down Syndrome Neurogenesis Using Human-Induced Pluripotent Stem Cells.
  26. The glymphatic system.
  1. Acta Neuropathol Commun. 2025 Mar 26. 13(1): 67
    C9ORF72 poly-PR disrupts expression of ALS/FTD-implicated STMN2 through SRSF7.
    Karen S Wang, Julie Smeyers, Kevin Eggan, Bogdan Budnik, Daniel A Mordes.
      A hexanucleotide repeat expansion in C9ORF72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and combined ALS/FTD. The repeat is transcribed in the sense and the antisense directions to produce several dipeptide repeat proteins (DPRs) that have toxic gain-of-function effects; however, the mechanisms by which DPRs lead to neural dysfunction remain unresolved. Here, we observed that poly-proline-arginine (poly-PR) was sufficient to inhibit axonal regeneration of human induced pluripotent stem cell (iPSC)-derived neurons. Global phospho-proteomics revealed that poly-PR selectively perturbs nuclear RNA binding proteins (RBPs). In neurons, we found that depletion of one of these RBPs, SRSF7 (serine/arginine-rich splicing factor 7), resulted in decreased abundance of STMN2 (stathmin-2), though not TDP-43. STMN2 supports axon maintenance and repair and has been recently implicated in the pathogenesis of ALS/FTD. We observed that depletion of SRSF7 impaired axonal regeneration, a phenotype that could be rescued by exogenous STMN2. We propose that antisense repeat-encoded poly-PR perturbs RBPs, particularly SRSF7, resulting in reduced STMN2 and axonal repair defects in neurons. Hence, we provide a potential link between DPRs gain-of-function effects and STMN2 loss-of-function phenotypes in neurodegeneration.
    DOI:  https://doi.org/10.1186/s40478-025-01977-2
  2. Channels (Austin). 2025 Dec;19(1): 2480713
    Electrophysiological characterization of sourced human iPSC-derived motor neurons.
    Bohumila Jurkovicova-Tarabova, Robin N Stringer, Zuzana Sevcikova Tomaskova, Norbert Weiss.
      Induced pluripotent stem cell (iPSC)-derived motor neurons provide a powerful platform for studying motor neuron diseases. These cells enable human-specific modeling of disease mechanisms and high-throughput drug screening. While commercially available iPSC-derived motor neurons offer a convenient alternative to time-intensive differentiation protocols, their electrophysiological properties and maturation require comprehensive evaluation to validate their utility for research and therapeutic applications. In this study, we characterized the electrophysiological properties of commercially available iPSC-derived motor neurons. Immunofluorescence confirmed the expression of motor neuron-specific biomarkers, indicating successful differentiation and maturation. Electrophysiological recordings revealed stable passive membrane properties, maturation-dependent improvements in action potential kinetics, and progressive increases in repetitive firing. Voltage-clamp analyses confirmed the functional expression of key ion channels, including high- and low-voltage-activated calcium channels, TTX-sensitive and TTX-insensitive sodium channels, and voltage-gated potassium channels. While the neurons exhibited hallmark features of motor neuron physiology, high input resistance, depolarized resting membrane potentials, and limited firing capacity suggest incomplete electrical maturation. Altogether, these findings underscore the potential of commercially available iPSC-derived motor neurons as a practical resource for MND research, while highlighting the need for optimized protocols to support prolonged culture and full maturation.
    Keywords:  Motor neuron; action potential; calcium current; iPSC; potassium current; sodium current
    DOI:  https://doi.org/10.1080/19336950.2025.2480713
  3. Cells. 2025 Mar 12. pii: 421. [Epub ahead of print]14(6):
    Microglia in ALS: Insights into Mechanisms and Therapeutic Potential.
    Silvano Bond, Smita Saxena, Julieth A Sierra-Delgado.
      Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by the loss of motor neurons, leading to escalating muscle weakness, atrophy, and eventually paralysis. While neurons are the most visibly affected, emerging data highlight microglia-the brain's resident immune cells-as key contributors to disease onset and progression. Rather than existing in a simple beneficial or harmful duality, microglia can adopt multiple functional states shaped by internal and external factors, including those in ALS. Collectively, these disease-specific forms are called disease-associated microglia (DAM). Research using rodent models, patient-derived cells, and human postmortem tissue shows that microglia can transition into DAM phenotypes, driving inflammation and neuronal injury. However, these cells can also fulfill protective roles under certain conditions, revealing their adaptable nature. This review explores recent discoveries regarding the multifaceted behavior of microglia in ALS, highlights important findings that link these immune cells to motor neuron deterioration, and discusses emerging therapies-some already used in clinical trials-that aim to recalibrate microglial functions and potentially slow disease progression.
    Keywords:  ALS; microglia; neuroinflammation
    DOI:  https://doi.org/10.3390/cells14060421
  4. Neurosci Res. 2025 Mar 22. pii: S0168-0102(25)00064-1. [Epub ahead of print]
    Optineurin knock-out forms TDP-43 aggregates to regulate TDP-43 protein levels despite autophagic up-regulation and aberrant TDP-43 expression.
    Yuta Maetani, Takashi Kurashige, Yui Tada, Kodai Kume, Tomoaki Watanabe, Yusuke Sotomaru, Koji Yamanaka, Hirofumi Maruyama, Hideshi Kawakami.
      Optineurin is a causative gene of amyotrophic lateral sclerosis (ALS) and has many roles in processes such as autophagy and inflammation. However, it is unclear how optineurin causes ALS. Optineurin knock-out (Optn-KO) mice, which have been generated by several researchers, exhibit motor neuron degeneration and TDP-43 aggregates, but no motor deficits. Motor dysfunction in ALS model mice is associated with TDP-43 in the spinal cord. We bred Optn-KO mice with TDP-43 overexpression transgenic mice and evaluated whether increased TDP-43 protein causes motor deficits and whether Optn-KO affects TDP-43 protein level. Optn-KO mice had spinal TDP-43 protein levels and motor function comparable to wild-type mice, and TDP-43-transgenic (TDP-43-tg) mice resulted in motor dysfunction and early death. However, double-mutant TDP-43-tg / Optn-KO mice had lower TDP-43 protein levels than TDP-43-tg mice at 18 months age, and showed inhibition of the TBK1-optinerurin autophagic pathway with aging. Furthermore, Optn-KO caused TDP-43-positive cytoplasmic aggregates. TDP-43 overexpression by itself induced spinal microgliosis, but Optn-KO suppressed that microgliosis. Finally, we showed that Optn-KO mice could not exhibit behavioral dysfunction because TDP-43 protein levels were not elevated despite autophagy inhibition. Thus, downregulation of Optn may suppress TDP-43 toxicity by regulating its abundance through aggregate formation.
    Keywords:  ALS; TDP-43; aggregate; autophagy; optineurin
    DOI:  https://doi.org/10.1016/j.neures.2025.03.005
  5. J Fungi (Basel). 2025 Feb 28. pii: 188. [Epub ahead of print]11(3):
    A Twist in Yeast: New Perspectives for Studying TDP-43 Proteinopathies in S. cerevisiae.
    Roberto Stella, Alessandro Bertoli, Raffaele Lopreiato, Caterina Peggion.
      TAR DNA-binding protein 43 kDa (TDP-43) proteinopathies are a group of neurodegenerative diseases (NDs) characterized by the abnormal accumulation of the TDP-43 protein in neurons and glial cells. These proteinopathies are associated with several NDs, including amyotrophic lateral sclerosis, frontotemporal lobar degeneration, and some forms of Alzheimer's disease. Yeast models have proven valuable in ND research due to their simplicity, genetic tractability, and the conservation of many cellular processes shared with higher eukaryotes. For several decades, Saccharomyces cerevisiae has been used as a model organism to study the behavior and toxicity of TDP-43, facilitating the identification of genes and pathways that either exacerbate or mitigate its toxic effects. This review will discuss evidence showing that yeast models of TDP-43 exhibit defects in proteostasis, mitochondrial function, autophagy, and RNA metabolism, which are key features of TDP-43-related NDs. Additionally, we will explore how modulating proteins involved in these processes reduce TDP-43 toxicity, aiding in restoring normal TDP-43 function or preventing its pathological aggregation. These findings highlight potential therapeutic targets for the treatment of TDP-43-related diseases.
    Keywords:  ALS; RNA metabolism; TDP-43; autophagy; chaperone; mitochondrial dysfunction; neurodegeneration; nucleolin; protein aggregation; yeast
    DOI:  https://doi.org/10.3390/jof11030188
  6. Mov Disord. 2025 Mar 28.
    Neurodegenerative and Neurodevelopmental Roles for Bulk Lipid Transporters VPS13A and BLTP2.
    Sarah D Neuman, Rajan S Thakur, Scott J Gratz, Kate M O'Connor-Giles, Arash Bashirullah.
       BACKGROUND: Bridge-like lipid transfer proteins (BLTPs) mediate bulk lipid transport at membrane contact sites. Mutations in BLTPs are linked to both early-onset neurodevelopmental and later-onset neurodegenerative diseases, including movement disorders. The tissue specificity and temporal requirements of BLTPs in disease pathogenesis remain poorly understood.
    OBJECTIVE: The objective of this study was to determine tissue-specific and aging-dependent roles for VPS13A and BLTP2 using Drosophila models.
    METHODS: We generated tissue-specific knockdowns of the VPS13A ortholog (Vps13) and the BLTP2 ortholog (hobbit) in neurons and muscles of Drosophila. We analyzed age-dependent locomotor behavior, neurodegeneration, and synapse development and function.
    RESULTS: Neuron-specific loss of the VPS13A ortholog caused neurodegeneration followed by aging-dependent movement deficits and reduced lifespan, whereas muscle-specific loss affected only lifespan. In contrast, neuronal loss of the BLTP2 ortholog resulted in severe early-onset locomotor defects without neurodegeneration, whereas muscle loss impaired synaptogenesis and neurotransmission at the neuromuscular junction.
    CONCLUSIONS: VPS13A maintains neuronal survival, whereas BLTP2 orchestrates synaptic development. The phenotypic specificity of BLTP function provides mechanistic insights into distinct disease trajectories for BLTP-associated disorders. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
    Keywords:  VPS13A; lipid transfer proteins; lipids; membrane contact sites; parkinsonism
    DOI:  https://doi.org/10.1002/mds.30178
  7. Nat Cell Biol. 2025 Mar 26.
    Proteostasis and lysosomal repair deficits in transdifferentiated neurons of Alzheimer's disease.
    Ching-Chieh Chou, Ryan Vest, Miguel A Prado, Joshua Wilson-Grady, Joao A Paulo, Yohei Shibuya, Patricia Moran-Losada, Ting-Ting Lee, Jian Luo, Steven P Gygi, Jeffery W Kelly, Daniel Finley, Marius Wernig, Tony Wyss-Coray, Judith Frydman.
      Ageing is the most prominent risk factor for Alzheimer's disease (AD). However, the cellular mechanisms linking neuronal proteostasis decline to the characteristic aberrant protein deposits in the brains of patients with AD remain elusive. Here we develop transdifferentiated neurons (tNeurons) from human dermal fibroblasts as a neuronal model that retains ageing hallmarks and exhibits AD-linked vulnerabilities. Remarkably, AD tNeurons accumulate proteotoxic deposits, including phospho-tau and amyloid β, resembling those in APP mouse brains and the brains of patients with AD. Quantitative tNeuron proteomics identify ageing- and AD-linked deficits in proteostasis and organelle homeostasis, most notably in endosome-lysosomal components. Lysosomal deficits in aged tNeurons, including constitutive lysosomal damage and ESCRT-mediated lysosomal repair defects, are exacerbated in AD tNeurons and linked to inflammatory cytokine secretion and cell death. Providing support for the centrality of lysosomal deficits in AD, compounds ameliorating lysosomal function reduce amyloid β deposits and cytokine secretion. Thus, the tNeuron model system reveals impaired lysosomal homeostasis as an early event of ageing and AD.
    DOI:  https://doi.org/10.1038/s41556-025-01623-y
  8. Biomolecules. 2025 Mar 18. pii: 433. [Epub ahead of print]15(3):
    The Balance of MFN2 and OPA1 in Mitochondrial Dynamics, Cellular Homeostasis, and Disease.
    Paola Zanfardino, Alessandro Amati, Mirko Perrone, Vittoria Petruzzella.
      Mitochondrial dynamics, governed by fusion and fission, are crucial for maintaining cellular homeostasis, energy production, and stress adaptation. MFN2 and OPA1, key regulators of mitochondrial fusion, play essential roles beyond their structural functions, influencing bioenergetics, intracellular signaling, and quality control mechanisms such as mitophagy. Disruptions in these processes, often caused by MFN2 or OPA1 mutations, are linked to neurodegenerative diseases like Charcot-Marie-Tooth disease type 2A (CMT2A) and autosomal dominant optic atrophy (ADOA). This review explores the molecular mechanisms underlying mitochondrial fusion, the impact of MFN2 and OPA1 dysfunction on oxidative phosphorylation and autophagy, and their role in disease progression. Additionally, we discuss the divergent cellular responses to MFN2 and OPA1 mutations, particularly in terms of proliferation, senescence, and metabolic signaling. Finally, we highlight emerging therapeutic strategies to restore mitochondrial integrity, including mTOR modulation and autophagy-targeted approaches, with potential implications for neurodegenerative disorders.
    Keywords:  autophagy; mTOR signaling; mitochondria; mitochondrial dynamics; mitophagy; neurodegenerative diseases; oxidative phosphorylation; proliferation; senescence
    DOI:  https://doi.org/10.3390/biom15030433
  9. Nat Commun. 2025 Mar 26. 16(1): 2975
    Non-muscle myosin II inhibition at the site of axon injury increases axon regeneration.
    Keunjung Heo, Tammy Szu-Yu Ho, Xiangsunze Zeng, Bruna Lenfers Turnes, Maryam Arab, Selwyn Jayakar, Kuchuan Chen, Georgios Kimourtzis, Michael C Condro, Elisa Fazzari, Xuan Song, J Tabitha Hees, Zhuqiu Xu, Xirui Chen, Lee B Barrett, Laura Perrault, Roshan Pandey, Kathleen Zhang, Aparna Bhaduri, Zhigang He, Harley I Kornblum, Jed Hubbs, Clifford J Woolf.
      Motor axon regeneration following peripheral nerve injury is critical for motor recovery but therapeutic interventions enhancing this are not available. We conduct a phenotypic screen on human motor neurons and identified blebbistatin, a non-muscle myosin II inhibitor, as the most effective neurite outgrowth promotor. Despite its efficacy in vitro, its poor bioavailability limits in vivo application. We, therefore, utilize a blebbistatin analog, NMIIi2, to explore its therapeutic potential for promoting axon regeneration. Local NMIIi2 application directly to injured axons enhances regeneration in human motor neurons. Furthermore, following a sciatic nerve crush injury in male mice, local NMIIi2 administration to the axonal injury site facilitates motor neuron regeneration, muscle reinnervation, and functional recovery. NMIIi2 also promotes axon regeneration in sensory, cortical, and retinal ganglion neurons. These findings highlight the therapeutic potential of topical NMII inhibition for treating axon damage.
    DOI:  https://doi.org/10.1038/s41467-025-58303-6
  10. Dis Model Mech. 2025 Mar 28. pii: dmm.052029. [Epub ahead of print]
    Patient-specific mutation of a contact site protein Tomm70 causes neurodegeneration in a zebrafish model.
    Vranda Garg, Ralf Heinrich, Roshan Priyarangana Perera, Till Ischebeck, Wiebke Möbius, Torben Ruhwedel, Patricia Scholz, Gabriela Salinas, Christian Dullin, Martin C Göpfert, Jacob Engelmann, Roland Dosch, Bart R H Geurten.
      Tomm70 is a receptor at the contact site between mitochondria and the endoplasmic reticulum, and has been identified as a risk gene for hereditary spastic paraplegia. Furthermore, de novo missense mutations in TOMM70 have been identified to cause neurological impairments in two unrelated patients. Here, we show that mutant zebrafish ruehreip25ca also harbor a missense mutation in tomm70, affecting the same conserved isoleucine residue as in one of the human patients. Using this model, we demonstrate how loss of Tomm70 function leads to impairment. At the molecular level, the mutation affects the interaction of Tomm70 with the endoplasmic reticulum protein Lam6, a known sterol transporter. At the neuronal level, the mutation impairs mitochondrial transport to the axons and dendrites, leading to demyelination of large calibre axons in the spinal cord. These neurodegenerative defects in zebrafish are associated with reduced endurance, swimming efficiency, and alterations in the C-start escape response, which correlate with decreased spiking in giant Mauthner neurons. Thus, in zebrafish, a mutation in the endoplasmic reticulum-mitochondria contact site protein Tomm70 recreates some of the neurodegenerative phenotypes characteristic of hereditary spastic paraplegia.
    Keywords:  Endoplasmic reticulum-mitochondria contact site (ER-MCS); Neurodegeneration; Tomm70; Zebrafish
    DOI:  https://doi.org/10.1242/dmm.052029
  11. Curr Biol. 2025 Mar 24. pii: S0960-9822(25)00132-0. [Epub ahead of print]35(6): R218-R221
    Cell biology: A new dynamin superfamily protein remodels mitochondrial dynamics.
    Hassan Hashimi.
      Dynamin superfamily proteins mediate mitochondrial fusion in fungi and animals. A new study expands the taxonomic reach of this superfamily and provides insights into the roles these proteins play by investigating MfnL, a family member involved in trypanosomal mitochondrial dynamics. Importantly, MfnL occurs widely in eukaryotes and prokaryotes.
    DOI:  https://doi.org/10.1016/j.cub.2025.01.069
  12. Ageing Res Rev. 2025 Mar 21. pii: S1568-1637(25)00085-6. [Epub ahead of print]108 102739
    Fluid-based biomarkers for neurodegenerative diseases.
    Yongliang Cao, Yifei Xu, Meiqun Cao, Nan Chen, Qingling Zeng, Mitchell K P Lai, Dahua Fan, Gautam Sethi, Yongkai Cao.
      Neurodegenerative diseases, such as Alzheimer's Disease (AD), Multiple Sclerosis (MS), Parkinson's Disease (PD), and Amyotrophic Lateral Sclerosis (ALS) are increasingly prevalent as global populations age. Fluid biomarkers, derived from cerebrospinal fluid (CSF), blood, saliva, urine, and exosomes, offer a promising solution for early diagnosis, prognosis, and disease monitoring. These biomarkers can reflect critical pathological processes like amyloid-beta (Aβ) deposition, tau protein hyperphosphorylation, α-syn misfolding, TDP-43 mislocalization and aggregation, and neuronal damage, enabling detection long before clinical symptoms emerge. Recent advances in blood-based biomarkers, particularly plasma Aβ, phosphorylated tau, and TDP-43, have shown diagnostic accuracy equivalent to CSF biomarkers, offering more accessible testing options. This review discusses the current challenges in fluid biomarker research, including variability, standardization, and sensitivity issues, and explores how combining multiple biomarkers with clinical symptoms improves diagnostic reliability. Ethical considerations, future directions involving extracellular vehicles (EVs), and the integration of artificial intelligence (AI) are also highlighted. Continued research efforts will be key to overcoming these obstacles, enabling fluid biomarkers to become crucial tools in personalized medicine for neurodegenerative diseases.
    Keywords:  Artificial; Diagnostic accuracy; Ethical considerations; Fluid biomarkers; Intelligence; Neurodegenerative diseases; Personalized medicine
    DOI:  https://doi.org/10.1016/j.arr.2025.102739
  13. Proc Natl Acad Sci U S A. 2025 Apr;122(13): e2426745122
    Targeted degradation of α-Synuclein using an evolved botulinum toxin protease.
    Philipp Sondermann, Christian S Diercks, Cynthia Rong, Peter G Schultz.
      There is considerable interest in the targeted degradation of proteins implicated in human disease. The use of sequence-specific proteases for this purpose is severely limited by the difficulty in engineering the numerous enzyme-substrate interactions required to yield highly selective proteases while maintaining catalytic activity. Herein, we report a strategy to evolve a protease for the programmed degradation of α-Synuclein, a presynaptic protein closely linked to Parkinson's disease. Our structure-guided evolution campaign uses the protease from botulinum neurotoxin and showcases the stepwise change of specificity from its native substrate SNAP25 to the selective degradation of α-Synuclein. The protease's selectivity is further demonstrated in human cells where near complete degradation of overexpressed human α-Synuclein is observed with no significant effects on cell proliferation. This stepwise strategy may serve as a general approach to evolve highly selective proteases targeting dysregulated proteins.
    Keywords:  Parkinson’s disease; botulinum neurotoxin; intrinsically disordered proteins; protease evolution; protein therapeutics
    DOI:  https://doi.org/10.1073/pnas.2426745122
  14. Lancet Neurol. 2025 Apr;pii: S1474-4422(25)00071-7. [Epub ahead of print]24(4): 282-284
    Uncontrolled CAG expansion in neurons susceptible to Huntington's disease.
    Alexandra Durr.
      
    DOI:  https://doi.org/10.1016/S1474-4422(25)00071-7
  15. EMBO J. 2025 Mar 24.
    S-palmitoylation modulates ATG2-dependent non-vesicular lipid transport during starvation-induced autophagy.
    Wenhui Zheng, Maomao Pu, Sai Zeng, Hongtao Zhang, Qian Wang, Tao Chen, Tianhua Zhou, Chunmei Chang, Dante Neculai, Wei Liu.
      Lipid transfer proteins mediate the non-vesicular transport of lipids at membrane contact sites to regulate the lipid composition of organelle membranes. Despite significant recent advances in our understanding of the structural basis for lipid transfer, its functional regulation remains unclear. In this study, we report that S-palmitoylation modulates the cellular function of ATG2, a rod-like lipid transfer protein responsible for transporting phospholipids from the endoplasmic reticulum (ER) to phagophores during autophagosome formation. During starvation-induced autophagy, ATG2A undergoes depalmitoylation as the balance between ZDHHC11-mediated palmitoylation and APT1-mediated depalmitoylation. Inhibition of ATG2A depalmitoylation leads to impaired autophagosome formation and disrupted autophagic flux. Further, in cell and in vitro analyses demonstrate that S-palmitoylation at the C-terminus of ATG2A anchors the C-terminus to the ER. Depalmitoylation detaches the C-terminus from the ER membrane, enabling it to interact with phagophores and promoting their growth. These findings elucidate a S-palmitoylation-dependent regulatory mechanism of cellular ATG2, which may represent a broad regulatory strategy for lipid transport mediated by bridge-like transporters within cells.
    Keywords:  ATG2; Autophagy; Lipid Transfer Protein; S-palmitoylation
    DOI:  https://doi.org/10.1038/s44318-025-00410-7
  16. Adv Biol (Weinh). 2025 Mar 24. e2400597
    Ameliorating TIMM50 Loss Slows Senescence by Improving Mitochondrial Structure and Function.
    Amrita Nepalia, Deepak Kumar Saini.
      Mitochondrial dysfunction is an irrefutable hallmark of cellular senescence and aging. The dysfunction is marked by increased mitochondrial volume and reduced function, typified by low Adenosine Triphosphate (ATP) production and higher Reactive Oxygen Species (ROS) generation. Over the years, this dysfunction has been linked to Electron Transport Chain (ETC) malfunction and low NAD levels, augmented by poor mitophagy. However, the genetic regulation of mitochondrial dysfunction is still not clear. Here, using several senescence models, the first report on the role of the downregulation of a mitochondrial protein, Translocase of Inner Mitochondrial Membrane 50 (TIMM50), in senescence is presented. The downregulation of TIMM50 is also sufficient for triggering senescence through impaired mitochondrial function, characterized using a variety of mitochondrial function assessment assays. Reduced levels of TIMM50 initiated all the hallmarks of senescence, and overexpression significantly slowed senescence onset in response to an external trigger. The pathway analysis revealed that TIMM50 loss is mediated by the sirtuin1-dependent downregulation of CCAAT enhancer binding protein alpha (CEBPα), a transcription activator for TIMM50 expression. To establish the translational value of the observation, screening several potential anti-aging compounds revealed TIMM50 stabilizing and senescence-delaying effects only for verapamil and mitochondrial ROS quencher, Mito (2-(2,2,6,6-Tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl)triphenylphosphonium chloride (MitoTEMPO), both known anti-aging entities. Overall, TIMM50 is identified as the key mitochondrial protein whose downregulation is a critical step in initiating cellular senescence.
    Keywords:  TIMM50; aging; cellular senescence; mitochondria; sirtuin
    DOI:  https://doi.org/10.1002/adbi.202400597
  17. Autophagy. 2025 Mar 26.
    R406 and its structural analogs reduce SNCA/α-synuclein levels via autophagic degradation.
    Chao Zhong, Xiaoge Gao, Qi Chen, Bowen Guan, Wanli Wu, Zhiqiang Ma, Mengdan Tao, Xihuan Liu, Yu Ding, Yiyan Fei, Yan Liu, Boxun Lu, Zhaoyang Li.
      The presence of neuronal Lewy bodies mainly composed of SNCA/α-synuclein aggregations is a pathological feature of Parkinson disease (PD), whereas reducing SNCA protein levels may slow the progression of this disease. We hypothesized that compounds enhancing SNCA's interaction with MAP1LC3/LC3 May increase its macroautophagic/autophagic degradation. Here, we conducted small molecule microarray (SMM)-based screening to identify such compounds and revealed that the compound R406 could decrease SNCA protein levels in an autophagy-dependent manner. We further validated the proposed mechanism, in which knockdown of essential gene ATG5 for autophagy formation and using the autophagy inhibitor chloroquine (CQ) blocked the effect of R406. Additionally, R406 also reduced the levels of phosphorylated serine 129 of SNCA (p-S129-SNCA) in SNCA preformed fibrils (PFFs)-induced cellular models and rescued neuron degeneration.
    Keywords:  Autophagic degradation; Snca/synuclein alpha; parkinson disease; small molecule compounds
    DOI:  https://doi.org/10.1080/15548627.2025.2483886
  18. Biomedicines. 2025 Feb 21. pii: 550. [Epub ahead of print]13(3):
    Transgenic iPSC Lines with Genetically Encoded MitoTimer to Study Mitochondrial Biogenesis in Dopaminergic Neurons with Tauopathy.
    Julia A Nadtochy, Sergey P Medvedev, Elena V Grigor'eva, Sophia V Pavlova, Julia M Minina, Anton V Chechushkov, Anastasia A Malakhova, Liudmila V Kovalenko, Suren M Zakian.
      Background: Tauopathy has been identified as a prevalent causative agent of neurodegenerative diseases, including frontotemporal dementia with parkinsonism-17 (FTDP-17). This rare hereditary neurodegenerative condition is characterised by the manifestation of parkinsonism and behavioural changes. The majority of cases of FTDP-17 are associated with mutations in the MAPT gene, which encodes the tau protein. MAPT mutations lead to disruption of the balance between 3R and 4R tau forms, which causes destabilisation of microtubules and impairment of cellular organelle functions, particularly mitochondrial dysfunction. The development of model systems and tools for studying the molecular, genetic, and biochemical mechanisms underlying FTDP-17 and testing therapies at the cellular level is an urgent necessity. Methods: In this study, we generated transgenic lines of induced pluripotent stem cells (iPSCs) from a patient carrying the pathogenic mutation c.2013T > G (rs63750756, p.N279K) of MAPT and a healthy donor. A doxycycline-controlled transgene of the genetically encoded biosensor MitoTimer was integrated into the AAVS1 locus of these cells. The MitoTimer biosensor allows for lifetime monitoring of the turnover of mitochondria in neuronal cells derived from directed iPSC differentiation. The fact that transcription of the transgene can be induced by doxycycline provides additional possibilities for pulse labelling of newly formed mitochondria. Results: Transgenic iPSC lines provide a unique tool to study the molecular and genetic mechanisms of FTDP-17 caused by the presence of the c.2013T > G (p.N279K) mutation, as well as to test potential drugs in vitro.
    Keywords:  CRISPR/Cas9; MAPT:c.2013T > G; MitoTimer biosensor; frontotemporal dementia with parkinsonism-17; induced pluripotent stem cells; mitochondrial dysfunction
    DOI:  https://doi.org/10.3390/biomedicines13030550
  19. Pharmaceutics. 2025 Mar 13. pii: 365. [Epub ahead of print]17(3):
    Therapeutic Efficacy of Small Extracellular Vesicles Loaded with ROCK Inhibitor in Parkinson's Disease.
    Candy Carbajal, Myosotys Rodriguez, Florida Owens, Nicole Stone, Dileepkumar Veeragoni, Rebecca Z Fan, Kim Tieu, Nazira El-Hage.
      Background/Objectives: Parkinson's disease (PD) is a rapidly growing neurological disorder in the developed world, affecting millions over the age of 60. The decline in motor functions occurs due to a progressive loss of midbrain dopaminergic neurons, resulting in lowered dopamine levels and impaired muscle function. Studies show defective mitochondrial autophagy (or "mitophagy") links to PD. Rho-associated coiled-coil containing protein kinases (ROCK) 1 and ROCK2 are serine/threonine kinases, and their inhibition can enhance neuroprotection in PD by promoting mitophagy. Methods: We examine the effects of ROCK inhibitor SR3677, delivered via macrophage-derived small extracellular vesicles (sEVs) to Parkin Q311X(A) PD mouse models. sEVs with SR3677, administered intranasally, increased mitophagy gene expression, reduced inflammatory factors, and elevated dopamine levels in brain tissues. Results: ROCK2 expression decreased, showing the drug's inhibitory effect. sEV-SR3677 treatment was more effective than treatment with the drug alone, although sham EVs showed lower effects. This suggests that EV-SR3677 not only activates mitochondrial processes but also promotes the degradation of damaged mitochondria through autophagy. Mitochondrial functional assays and oxygen consumption in ex vivo glial cultures revealed that sEV-SR3677 significantly improved mitochondrial respiration compared to that in untreated or SR3677-only treated cells. Conclusion: We demonstrated the efficacy of ROCK2 inhibition on mitochondrial function via sEV-SR3677 in the PD mouse model, necessitating further studies to explore design challenges and mechanisms of sEV-SR3677 as mitochondria-targeted therapy for PD.
    Keywords:  Parkinson’s disease; ROCK; drug delivery system; extracellular vesicles; intranasal delivery
    DOI:  https://doi.org/10.3390/pharmaceutics17030365
  20. Pathogens. 2025 Mar 14. pii: 286. [Epub ahead of print]14(3):
    Human Retinal Organoid Model of Ocular Toxoplasmosis.
    Liam M Ashander, Grace E Lidgerwood, Amanda L Lumsden, João M Furtado, Alice Pébay, Justine R Smith.
      The health burden of ocular toxoplasmosis is substantial, and there is an unmet need for safe and curative anti-microbial drugs. One major barrier to research on new therapeutics is the lack of in vitro human-based models beyond two-dimensional cultured cells and tissue explants. We aimed to address this research gap by establishing a human retinal organoid model of ocular toxoplasmosis. Retinal organoids, generated from human induced pluripotent stem cells and grown to two stages of organization, were incubated with a suspension of live or heat-killed GT-1 strain T. gondii tachyzoites, or medium without tachyzoites. Both developing (1 month post-isolation) and matured (6 months post-isolation) organoids were susceptible to infection. Spread of live parasites from the margin to the entire organoid over 1 week was indicated by immunolabelling for T. gondii surface antigen 1. This progression was accompanied by changes in the levels of selected tachyzoite transcripts-SAG1, GRA6, and ROP16-and human cytokine transcripts-CCL2, CXCL8, CXCL10, and IL6-in infected versus control conditions. Our human retinal organoid model of ocular toxoplasmosis offers the opportunity for many future lines of study, including tachyzoite interactions with retinal cell populations and leukocyte subsets, parasite stage progression, and disease processes of different T. gondii strains, as well as drug testing.
    Keywords:  ocular toxoplasmosis; retinitis; uveitis
    DOI:  https://doi.org/10.3390/pathogens14030286
  21. Nat Cell Biol. 2025 Mar 21.
    In situ architecture of the human prohibitin complex.
    Felix Lange, Michael Ratz, Jan-Niklas Dohrke, Maxence Le Vasseur, Dirk Wenzel, Peter Ilgen, Dietmar Riedel, Stefan Jakobs.
      Prohibitins are a highly conserved family of proteins that have been implicated in a variety of functions including mitochondrial stress signalling and housekeeping, cell cycle progression, apoptosis, lifespan regulation and many others. The human prohibitins prohibitin 1 and prohibitin 2 have been proposed to act as scaffolds within the mitochondrial inner membrane, but their molecular organization has remained elusive. Here we determined the molecular organization of the human prohibitin complex within the mitochondrial inner membrane using an integrative structural biology approach combining quantitative western blotting, cryo-electron tomography, subtomogram averaging and molecular modelling. The proposed bell-shaped structure consists of 11 alternating prohibitin 1 and prohibitin 2 molecules. This study reveals an average of about 43 prohibitin complexes per crista, covering 1-3% of the crista membrane area. These findings provide a structural basis for understanding the functional contributions of prohibitins to the integrity and spatial organization of the mitochondrial inner membrane.
    DOI:  https://doi.org/10.1038/s41556-025-01620-1
  22. Nat Commun. 2025 Mar 21. 16(1): 2810
    Dependence of mitochondrial calcium signalling and dynamics on the disaggregase, CLPB.
    Donato D'Angelo, Víctor H Sánchez-Vázquez, Benjamín Cartes-Saavedra, Denis Vecellio Reane, Ryan R Cupo, Hilda Delgado de la Herran, Giorgia Ghirardo, James Shorter, Ron A Wevers, Saskia B Wortmann, Fabiana Perocchi, Rosario Rizzuto, Anna Raffaello, György Hajnóczky.
      Cells utilize protein disaggregases to avoid abnormal protein aggregation that causes many diseases. Among these, caseinolytic peptidase B protein homolog (CLPB) is localized in the mitochondrial intermembrane space and linked to human disease. Upon CLPB loss, MICU1 and MICU2, regulators of the mitochondrial calcium uniporter complex (mtCU), and OPA1, a main mediator of mitochondrial fusion, become insoluble but the functional outcome remains unclear. In this work we demonstrate that CLPB is required to maintain mitochondrial calcium signalling and fusion dynamics. CLPB loss results in altered mtCU composition, interfering with mitochondrial calcium uptake independently of cytosolic calcium and mitochondrial membrane potential. Additionally, OPA1 decreases, and aggregation occurs, accompanied by mitochondrial fragmentation. Disease-associated mutations in the CLPB gene present in skin fibroblasts from patients also display mitochondrial calcium and structural changes. Thus, mtCU and fusion activity are dependent on CLPB, and their impairments might contribute to the disease caused by CLPB variants.
    DOI:  https://doi.org/10.1038/s41467-025-57641-9
  23. Front Biosci (Landmark Ed). 2025 Mar 20. 30(3): 27091
    Monitoring Autophagy in Human Aging: Key Cell Models and Insights.
    Tatiana M Moreno, Jose L Nieto-Torres, Caroline Kumsta.
      Autophagy, a key cellular degradation and recycling pathway, is critical for maintaining cellular homeostasis and responding to metabolic and environmental stress. Evidence for age-related autophagic dysfunction and its implications in chronic age-related diseases including neurodegeneration is accumulating. However, as a complex, multi-step process, autophagy can be challenging to measure, particularly in humans and human aging- and disease-relevant models. This review describes the links between macroautophagy, aging, and chronic age-related diseases. We present three novel human cell models, peripheral blood mononuclear cells (PBMCs), primary dermal fibroblasts (PDFs), and induced neurons (iNs), which serve as essential tools for studying autophagy flux and assessing its potential as a biomarker for aging. Unlike traditional models, these cell models retain age- and disease-associated molecular signatures, enhancing their relevance for human studies. The development of robust tools and methodologies for measuring autophagy flux in human cell models holds promise for advancing our understanding of autophagy's role in aging and age-related diseases, ultimately facilitating the discovery of therapies to enhance health outcomes.
    Keywords:  aging; autophagy; biomarkers; chronic age-related diseases; human cell models; induced neurons (iNs); peripheral blood mononuclear cells (PBMCs); primary dermal fibroblasts (PDFs)
    DOI:  https://doi.org/10.31083/FBL27091
  24. Neural Regen Res. 2025 Mar 25.
    Secretory autophagy in neurons: more than throwing out the trash?
    Alexander Veh, Patrick Lüningschrör.
      
    DOI:  https://doi.org/10.4103/NRR.NRR-D-24-01514
  25. J Vis Exp. 2025 Mar 07.
    In Vitro Modeling of Down Syndrome Neurogenesis Using Human-Induced Pluripotent Stem Cells.
    Vishi Sharma, Harish Chhawari, Pournima Joshi, Sunita Nehra, Nishant Singhal.
      Down syndrome (DS), caused by an extra copy of chromosome 21, is a leading cause of intellectual disability. One of the key factors contributing to this intellectual disability is impaired neurogenesis observed from fetal stages onwards. To study these neurodevelopmental abnormalities, human-induced pluripotent stem cells (hiPSCs) generated using cells obtained from DS patients provide a valuable and relevant model. Here, a comprehensive protocol is described for recapitulating DS-impaired neurogenesis observed during DS fetal stages. This protocol utilizes a pair of DS-hiPSCs having three copies of chromosome 21 and its isogenic euploid hiPSCs having two copies of chromosome 21. Importantly, the protocol described here recapitulates DS-impaired neurogenesis and found that biphasic cell cycle defect, i.e., reduced proliferation of DS neural progenitor cells (NPC) during the early phase of the neurogenic stage followed by increased proliferation of DS NPC during the late phase of the neurogenic stage is the cause of DS impaired neurogenesis. Increased proliferation of DS NPC during the late phase of the neurogenic stage leads to delayed exit from the cell cycle, causing reduced generation of post-mitotic neurons from DS NPCs. This protocol includes detailed steps for the maintenance of hiPSCs, their differentiation into neural lineages displaying biphasic cell cycle defect during the neurogenic stage, and the subsequent validation of reduced neural differentiation in DS cells. By following this methodology, researchers can create a robust experimental system that mimics the neurodevelopmental conditions of DS, enabling them to explore the specific alterations in brain development caused by trisomy 21.
    DOI:  https://doi.org/10.3791/67382
  26. Handb Clin Neurol. 2025 ;pii: B978-0-443-19104-6.00006-1. [Epub ahead of print]209 161-170
    The glymphatic system.
    Hashmat Ghanizada, Maiken Nedergaard.
      The glymphatic system, a brain-wide network-supporting cerebrospinal fluid (CSF) and interstitial fluid (ISF) exchange, is essential for removing metabolic waste from the brain. This system's proper functioning is crucial for maintaining neural health and preventing the accumulation of harmful substances that can lead to neurodegenerative diseases. This chapter explores the glymphatic system's mechanisms, its dysfunction in various neurologic disorders, and potential therapeutic strategies. Recent discoveries reveal the glymphatic system's involvement in aging, sleep, cerebral edema, and conditions, such as Alzheimer, Parkinson, Huntington diseases, amyotrophic lateral sclerosis, small vessel disease, hydrocephalus, migraine, stroke, traumatic brain injury, and psychiatric disorders, where impaired waste clearance contributes to disease pathogenesis. Moreover, therapeutic interventions targeting glymphatic dysfunction present promising avenues for mitigating the effects of neurodegenerative diseases. The chapter underscores the potential of integrating glymphatic research into broader clinical practices, offering new strategies for disease management and prevention.
    Keywords:  Acute neurologic diseases; Brain fluid; Convective; Efflux; Glymphatic-lymphatic; Influx; Neurodegenerative diseases; Pulsatility; Vasomotion
    DOI:  https://doi.org/10.1016/B978-0-443-19104-6.00006-1
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