bims-axbals 2025-06-01 papers

bims-axbals

Biomed News

on Axonal biology and ALS

Issue of 2025–06–01
thirty-six papers selected by
TJ Krzystek

Leucine-rich repeat kinase 2 biomarkers for Parkinson's disease.
LRRK2-mediated mitochondrial dysfunction in Parkinson's disease.
An adenine model of inborn metabolism errors alters TDP-43 aggregation and reduces its toxicity in yeast revealing insights into protein misfolding diseases.
Molecular Mechanisms of Protein Aggregation in ALS-FTD: Focus on TDP-43 and Cellular Protective Responses.
Viral-mediated knockdown of Atxn2 attenuates TDP-43 pathology and muscle dysfunction in the PFN1C71G ALS mouse model.
TDP-43 overexpression in the hypothalamus drives neuropathology, dysregulates metabolism and impairs behavior in mice.
Inhibition of PolyGA Dipeptide Repeat Protein Aggregation by Nucleic Acid Aptamers in C9 Amyotrophic Lateral Sclerosis-Frontotemporal Dementia Models.
Screening of candidate analgesics using a patient-derived human iPSC model of nociception identifies putative compounds for therapeutic treatment.
Current Challenges in Elucidating ALS Disease Mechanisms and Therapeutic Advances.
Intra-condensate demixing of TDP-43 inside stress granules generates pathological aggregates.
The power of connections: Recent advances in understanding the regulation of mitochondrial dynamics by membrane contact sites.
Exploring Protein Misfolding in Amyotrophic Lateral Sclerosis: Structural and Functional Insights.
Actin in mitochondrial regulation and mechanometabolic crosstalk.
c-Abl/TFEB Pathway Activation as a Common Pathogenic Mechanism in Lysosomal Storage Diseases: Therapeutic Potential of c-Abl Inhibitors.
Endoplasmic reticulum tubule junctions are sites of autophagy.
Phosphoinositides: Nanoscale Effects on Neuronal Membranes.
Recovery of Lysosomal Acidification and Autophagy Flux by Attapulgite Nanorods: Therapeutic Potential for Lysosomal Disorders.
Screening for variable drug responses using human iPSC cohorts.
An optimized method for directed differentiation of hypothalamic neural stem cells in a 3D culture system.
UPS10 inhibits the degradation of α-synuclein, a pathogenic factor associated with Parkinson's disease, by inhibiting chaperone-mediated autophagy.
Intracellular Inclusions Induced by Patient-Derived and Amplified α-Synuclein Aggregates Are Morphologically Indistinguishable.
Tunable metastability of condensates reconciles their dual roles in amyloid fibril formation.
Glutamatergic Regulation of miRNA-Containing Intraluminal Vesicle Trafficking and Extracellular Vesicle Secretion From Cortical Neurons.
Inhibition of mitochondrial protein import and proteostasis by a pro-apoptotic lipid.
Loss of UBE3A impacts both neuronal and non-neuronal cells in human cerebral organoids.
Extracellular Vesicles in the Crosstalk of Autophagy and Apoptosis: A Role for Lipid Rafts.
Restoring calcium crosstalk between ER and mitochondria promotes intestinal stem cell rejuvenation through autophagy in aged Drosophila.
A potential role for NADPH oxidase (NOX1/2) in mutant huntingtin-induced anomalous neurite outgrowth.
Mechanisms of heme transport in the mitochondria.
Macroautophagy at the service of synapses.
Three-dimensional super-resolution imaging of whole cells using a high numerical aperture oblique-plane microscope.
Dynamic regulation of vesicle pools in a detailed spatial model of the complete synaptic vesicle cycle.
Aging-induced alterations in microglial cells and their impact on neurodegenerative disorders.
Ngn2-Induced Differentiation of the NG108-15 Cell Line Enhances Motor Neuronal Differentiation and Neuromuscular Junction Formation.
Vitamin C Transport Deficiency Alters Striatal Dopamine Gene Expression and Metabolism in YAC128 Huntington Disease Mice.
Microtubule nucleation at the Golgi-related membrane organelles of mouse neurons.

Biochem J. 2025 May 28. pii: BCJ20253099. [Epub ahead of print]482(11):

Leucine-rich repeat kinase 2 biomarkers for Parkinson's disease.

Nicolas Dzamko.

  Leucine-rich repeat kinase 2 (LRRK2) has emerged as a promising therapeutic target for the treatment of neurodegenerative Parkinson's disease (PD). Data from a multitude of pre-clinical models are supportive of a potential role for LRRK2 therapies to ameliorate cellular dysfunctions found in PD, and small molecules to inhibit LRRK2 kinase activity, as well as antisense oligonucleotides to target the protein itself, are in clinical trials. Despite this, exactly how LRRK2 contributes to PD pathogenesis remains to be determined, and definitive biomarkers to track LRRK2 function are still required. Such biomarkers can be useful for monitoring the pharmacodynamic response of LRRK2 therapeutics and/or understanding the relationship between LRRK2 and the clinical progression of PD. Moreover, biomarkers that can identify increased LRRK2 levels or activity beyond just carriers of pathogenic LRRK2 mutations will be important for expanding LRRK2 therapeutics to other PD populations. This review summarizes recent findings regarding biomarkers of LRRK2.

Keywords:  LRRK2; Rab GTPase; biomarker; lysosome; mitochondria

DOI:  https://doi.org/10.1042/BCJ20253099
Biochem J. 2025 May 28. pii: BCJ20253062. [Epub ahead of print]482(11):

LRRK2-mediated mitochondrial dysfunction in Parkinson's disease.

Silas A Buck, Laurie H Sanders.

  Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor symptoms including tremor, rigidity, and bradykinesia as well as degeneration of dopamine (DA) neurons in the substantia nigra pars compacta (SNc). A minority of PD cases are familial and are caused by a single genetic mutation. One of the most common PD-causing genes is leucine-rich repeat kinase 2 (LRRK2), which causes an autosomal dominant PD that presents very similarly to sporadic PD. Pathogenic mutations in LRRK2 increase its kinase activity, indicated by both LRRK2 autophosphorylation and phosphorylation of its substrates. To date, the mechanism(s) by which elevated LRRK2 kinase activity induces DA neuron degeneration and PD has not been fully elucidated. One potential mechanism may involve the role of LRRK2 on mitochondria, as mitochondrial dysfunction has been linked to PD pathogenesis, and exciting recent evidence has connected PD pathogenic mutations in LRRK2 to multiple aspects of mitochondrial dysfunction associated with the disease. In this review, we discuss the current knowledge implicating LRRK2 in mitochondrial energetics, oxidative stress, genome integrity, fission/fusion, mitophagy, and ion/protein transport in PD, as well as examine the potential role LRRK2 may play in mediating the effects of mitochondrial therapeutics being investigated for treatment of PD.

Keywords:  LRRK2; Parkinson’s disease; mitochondria; mitochondrial DNA; mitophagy

DOI:  https://doi.org/10.1042/BCJ20253062
Microb Cell. 2025 ;12 119-130

An adenine model of inborn metabolism errors alters TDP-43 aggregation and reduces its toxicity in yeast revealing insights into protein misfolding diseases.

Sangeun Park, Sei-Kyoung Park, Peter Blair, Susan W Liebman.

  TDP-43 is linked to human diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal degeneration (FTD). Expression of TDP-43 in yeast is known to be toxic, cause cells to elongate, form liquid-like aggregates, and inhibit autophagy and TOROID formation. Here, we used the apt1∆ aah1∆ yeast model of inborn errors of metabolism, previously shown to lead to intracellular adenine accumulation and adenine amyloid-like fiber formation, to explore interactions with TDP-43. Results show that the double deletion shifts the TDP-43 aggregates from liquid-like droplets toward a more amyloid-like state. At the same time the deletions reduce TDP-43's effects on toxicity, cell morphology, autophagy, and TOROID formation without affecting the level of TDP-43. This suggests that the liquid-like droplets rather than amyloid-like TDP-43 aggregates are responsible for the deleterious effects in yeast. How the apt1∆ aah1∆ deletions alter TDP-43 aggregate formation is not clear. Possibly, it results from adenine and TDP-43 fiber interactions as seen for other heterologous fibers. This work offers new insights into the potential interactions between metabolite-based amyloids and pathological protein aggregates, with broad implications for understanding protein misfolding diseases.

Keywords:  ALS; FRAP; TDP-43; liquid-like droplets; metabolism disorders; metabolite-based amyloids; yeast

DOI:  https://doi.org/10.15698/mic2025.05.850
Cells. 2025 05 08. pii: 680. [Epub ahead of print]14(10):

Molecular Mechanisms of Protein Aggregation in ALS-FTD: Focus on TDP-43 and Cellular Protective Responses.

Enza Maria Verde, Valentina Secco, Andrea Ghezzi, Jessica Mandrioli, Serena Carra.

  Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD) are two neurodegenerative disorders that share common genes and pathomechanisms and are referred to as the ALS-FTD spectrum. A hallmark of ALS-FTD pathology is the abnormal aggregation of proteins, including Cu/Zn superoxide dismutase (SOD1), transactive response DNA-binding protein 43 (TDP-43), fused in sarcoma/translocated in liposarcoma (FUS/TLS), and dipeptide repeat proteins resulting from C9orf72 hexanucleotide expansions. Genetic mutations linked to ALS-FTD disrupt protein stability, phase separation, and interaction networks, promoting misfolding and insolubility. This review explores the molecular mechanisms underlying protein aggregation in ALS-FTD, with a particular focus on TDP-43, as it represents the main aggregated species inside pathological inclusions and can also aggregate in its wild-type form. Moreover, this review describes the protective mechanisms activated by the cells to prevent protein aggregation, including molecular chaperones and post-translational modifications (PTMs). Understanding these regulatory pathways could offer new insights into targeted interventions aimed at mitigating cell toxicity and restoring cellular function.

Keywords:  ALS-FTD; TDP-43; post-translational modifications; protein aggregation; stress granules

DOI:  https://doi.org/10.3390/cells14100680
Acta Neuropathol Commun. 2025 May 24. 13(1): 116

Viral-mediated knockdown of Atxn2 attenuates TDP-43 pathology and muscle dysfunction in the PFN1C71G ALS mouse model.

Zachary C E Hawley, Xueying Li, Dora Bodnar, Yuanzheng Gu, Yi Luo, Daniel Ferretti, Adam Sheehy, Rachelle Driscoll, Maria I Zavodszky, Shaolong Cao, Isabel Isaza, Luke Jandreski, Yuqing Liu, Thomas Carlile, Shih-Ching Lo, Anna Grimard, Shawn Bourque, Aditya Utturkar, Samantha Desmarais, H Moore Arnold, Dann Huh, Edward Guilmette, Deborah Y Kwon.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive motor neuron loss and muscle atrophy. Hyperphosphorylated aggregation of the RNA-binding protein, TDP-43, in the motor cortex and spinal cord are defining molecular features of ALS, suggesting TDP-43 dysfunction underlies disease pathogenesis. This phenomenon, however, has been difficult to recapitulate endogenously in animal models, impeding characterization of TDP-43 pathobiology in neurodegeneration. In this study, we report age-dependent accumulation of TDP-43 pathology in the spinal cord and progressive muscle-related deficits in transgenic mice expressing the ALS-associated PFN1C71G mutant protein. We show that transgenic neuronal expression of PFN1C71G induces early hyperphosphorylation of endogenous TDP-43 in the spinal cord that augments over time, preceding accumulation of insoluble non-phosphorylated TDP-43 and the manifestation of muscle denervation and motor dysfunction. Sustained knockdown of Atxn2 in the central nervous system (CNS) in pre-symptomatic PFN1C71G mice by AAV-driven expression of an artificial microRNA (AAV-amiR-Atxn2) reduces aberrant TDP-43 in the spinal cord, while delaying neurodegeneration and improving muscle and motor function. RNA-sequencing analysis of spinal cord samples from PFN1C71G mice and ALS donors show shared patterns of transcriptional perturbation, including a pro-inflammatory gene signature that is attenuated by AAV-amiR-Atxn2. Notably, impaired regulation of the PFN1C71G skeletal muscle transcriptome exceeds that of the spinal cord and is also improved by Atxn2 reduction in the CNS. Lastly, we find significant gene co-expression network homology between PFN1C71G mice and human ALS, with shared dysregulation of modules related to neuroinflammation and neuronal function and uncover novel hub genes that provide biological insight into ALS and potential drug targets that can be further investigated in this mouse model.

DOI: https://doi.org/10.1186/s40478-025-02005-z
Acta Neuropathol Commun. 2025 May 27. 13(1): 119

TDP-43 overexpression in the hypothalamus drives neuropathology, dysregulates metabolism and impairs behavior in mice.

Sofia Bergh, Nicolas Casadei, Sanaz Gabery, Oskar Simonsson, João M N Duarte, Deniz Kirik, Huu Phuc Nguyen, Åsa Petersén.

  TAR DNA-binding protein 43 (TDP-43) pathology is linked to the neurodegenerative disorders amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD) and Huntington disease (HD). Dysregulation of metabolism and emotion is shared across these disorders and may be caused by hypothalamic pathology. Inclusions with TDP-43 are present in the hypothalamus in clinical ALS, as well as selective loss of hypothalamic neurons expressing the metabolism and emotion regulating neuropeptides hypocretin (orexin), melanin-concentrating hormone (MCH) and oxytocin. We aimed to investigate whether there is a casual link between the effects of TDP-43 in the hypothalamus and the development of neuropathology, as well as changes in metabolism and behavior. We generated an adeno-associated viral (AAV) vector expressing human TDP-43 under the neuronal-specific synapsin promoter, which was injected bilaterally into the hypothalamus of wild-type FVB/N mice. TDP-43 overexpression resulted in hypothalamic pathology in a dose-dependent fashion replicating clinical pathology with hypothalamic atrophy and loss of hypocretin-, MCH- and oxytocin-expressing neurons. Nuclear and cytoplasmic inclusions of TDP-43 were found in the hypothalamus. Mice overexpressing TDP-43 in the hypothalamus developed metabolic dysregulation with hyperglycaemia independent of food intake. Additionally, mice overexpressing TDP-43 in the hypothalamus exhibited reduced motor activity and nesting ability, suggesting the development of an apathy-like phenotype. Taken together, AAV-vector mediated TDP-43 overexpression in the hypothalamus leads to neuropathology with the development of metabolic dysfunction and apathy-like behavior. These results indicate that TDP-43 can exert direct pathological effects in the hypothalamus, which may contribute to the development of the non-motor phenotype in TDP-43 proteinopathies.

Keywords:  (4 to 6): TDP-43; Amyotrophic lateral sclerosis; Frontotemporal dementia; Hypothalamus; Metabolism

DOI:  https://doi.org/10.1186/s40478-025-02018-8
Mol Neurobiol. 2025 May 24.

Inhibition of PolyGA Dipeptide Repeat Protein Aggregation by Nucleic Acid Aptamers in C9 Amyotrophic Lateral Sclerosis-Frontotemporal Dementia Models.

Swati Jain, Debanjana Das, Abhiyanta Mukherjee, Ipsita Roy.

  Hexanucleotide (GGGGCC) repeat expansion in non-coding region of C9ORF72 is the main genetic cause of amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD). Gain of toxic function, via RNA or proteins, or loss of function via haploinsufficiency, are probable mechanisms of disease progression. Expanded GGGGCC repeat codes for dipeptide repeat (DPR) proteins which form inclusions in the brain. Among all the dipeptides, aggregates formed by polyGA sequence are the most toxic. In this work, inhibition of aggregation of polyGA DPRs using aptamers has been explored as a therapeutic strategy to delay disease progression. Target-specific, high-affinity RNA aptamers were selected against monomeric (GA)30. Selected aptamers showed significant inhibition of aggregation of (GA)30 in vitro. Inhibitory RNA sequences were seen to form typical secondary structures which was missing in a non-inhibitory sequence. Some of the RNA aptamers showed increased solubilisation of DPRs formed by (GA)30 and (GA)60 in a neuronal cell model of ALS-FTD. Decreased aggregation was accompanied by lower oxidative stress and improved cell survival. Importantly, expression level of one of the markers of autophagy was significantly enhanced in the presence of aptamers, explaining lower aggregation observed in these cells. Thus, aptamers may be developed as potential therapeutic agents in C9 ALS-FTD.

Keywords:  Autophagy; C9ORF72; Dipeptide repeat proteins; Protein aggregation; RAN translation

DOI:  https://doi.org/10.1007/s12035-025-05075-1
Clin Transl Med. 2025 May;15(5): e70339

Screening of candidate analgesics using a patient-derived human iPSC model of nociception identifies putative compounds for therapeutic treatment.

Jack R Thornton, Alberto Capurro, Sally Harwood, Thomas C Henderson, Adrienne Unsworth, Franziska Görtler, Sushma Nagaraja-Grellscheid, Vsevolod Telezhkin, Majlinda Lako, Evelyne Sernagor, Lyle Armstrong.

   BACKGROUND AND PURPOSE: In this study, we applied an induced pluripotent stem cell (iPSC)-based model of inherited erythromelalgia (IEM) to screen a library of 281 small molecules, aiming to identify candidate pain-modulating compounds.
EXPERIMENTAL APPROACH: Human iPSC-derived sensory neuron-like cells, which exhibit action potentials in response to noxious stimulation, were evaluated using whole-cell patch-clamp and microelectrode array (MEA) techniques.
KEY RESULTS: Sensory neuron-like cells derived from individuals with IEM showed spontaneous electrical activity characteristic of genetic pain disorders. The drug screen identified four compounds (AZ106, AZ129, AZ037 and AZ237) that significantly decreased spontaneous firing with minimal toxicity. The calculated IC50 values indicate the potential efficacy of these compounds. Electrophysiological analysis confirmed the compounds' ability to reduce action potential generation in IEM patient-specific iPSC-derived sensory neuron-like cells.
CONCLUSIONS AND IMPLICATIONS: Our screening approach demonstrates the reproducibility and effectiveness of human neuronal disease modelling offering a promising avenue for discovering new analgesics. These findings address a critical gap in current therapeutic strategies for both general and neuropathic pain, warranting further investigation. This study highlights the innovative use of patient-derived iPSC sensory neuronal models in pain research and emphasises the potential for personalised medicine in developing targeted analgesics.
KEY POINTS: Utilisation of human iPSCs for efficient differentiation into sensory neuron-like cells offers a novel strategy for studying pain mechanisms. IEM sensory neuron-like cells exhibit key biomarkers and generate action potentials in response to noxious stimulation. IEM sensory neuron-like cells display spontaneous electrical activity, providing a relevant nociceptive model. Screening of 281 compounds identified four candidates that significantly reduced spontaneous firing with low cytotoxicity. Electrophysiological profiling of selected compounds revealed promising insights into their mechanisms of action, specifically modulating the NaV 1.7 channel for targeted analgesia.

Keywords:  analgesic candidates; drug screening; electrophysiology; induced pluripotent stem cells (iPSCs); inherited erythromelalgia (IEM); sensory neuron

DOI:  https://doi.org/10.1002/ctm2.70339
Cells. 2025 05 14. pii: 715. [Epub ahead of print]14(10):

Current Challenges in Elucidating ALS Disease Mechanisms and Therapeutic Advances.

Smita Saxena, W David Arnold.

As a researcher and a physician working together to combat amyotrophic lateral sclerosis (ALS), we are acutely aware of both the urgent need for innovation and the persistent divide between laboratory discoveries and clinical care [...].

DOI: https://doi.org/10.3390/cells14100715
Cell. 2025 May 15. pii: S0092-8674(25)00509-4. [Epub ahead of print]

Intra-condensate demixing of TDP-43 inside stress granules generates pathological aggregates.

Xiao Yan, David Kuster, Priyesh Mohanty, Jik Nijssen, Karina Pombo-García, Jorge Garcia Morato, Azamat Rizuan, Titus M Franzmann, Aleksandra Sergeeva, Anh M Ly, Feilin Liu, Patricia M Passos, Leah George, Szu-Huan Wang, Jayakrishna Shenoy, Helen L Danielson, Busra Ozguney, Alf Honigmann, Yuna M Ayala, Nicolas L Fawzi, Dennis W Dickson, Wilfried Rossoll, Jeetain Mittal, Simon Alberti, Anthony A Hyman.

  Cytosolic aggregation of the nuclear protein TAR DNA-binding protein 43 (TDP-43) is associated with many neurodegenerative diseases, but the triggers for TDP-43 aggregation are still debated. Here, we demonstrate that TDP-43 aggregation requires a double event. One is up-concentration in stress granules beyond a threshold, and the other is oxidative stress. These two events collectively induce intra-condensate demixing, giving rise to a dynamic TDP-43-enriched phase within stress granules, which subsequently transition into pathological aggregates. Intra-condensate demixing of TDP-43 is observed in iPS-motor neurons, a disease mouse model, and patient samples. Mechanistically, intra-condensate demixing is triggered by local unfolding of the RRM1 domain for intermolecular disulfide bond formation and by increased hydrophobic patch interactions in the C-terminal domain. By engineering TDP-43 variants resistant to intra-condensate demixing, we successfully eliminate pathological TDP-43 aggregates in cells. We suggest that up-concentration inside condensates followed by intra-condensate demixing could be a general pathway for protein aggregation.

Keywords:  ALS; FTD; TDP-43; biomolecular condensate; intra-condensate demixing; neurodegenerative diseases; oxidative stress; phase separation; protein aggregation; stress granules

DOI:  https://doi.org/10.1016/j.cell.2025.04.039
Curr Opin Cell Biol. 2025 May 28. pii: S0955-0674(25)00073-0. [Epub ahead of print]95 102535

The power of connections: Recent advances in understanding the regulation of mitochondrial dynamics by membrane contact sites.

Jason C Casler, Laura L Lackner.

The continuous remodeling of the mitochondrial network through fusion, fission, transport, and turnover events, collectively known as mitochondrial dynamics, is essential for the maintenance of mitochondrial metabolic and genomic health. While the primary molecular machines that mediate these processes were discovered decades ago, the regulation of mitochondrial dynamics clearly involves additional factors. A major breakthrough came from the discovery that sites of close apposition between organelles, known as membrane contact sites (MCSs), serve as critical regulators of organelle function. MCSs between mitochondria and the ER are now universally recognized as important regulatory hubs of mitochondrial dynamics. Despite this, there are still many unknowns pertaining to the mechanisms by which MCSs influence mitochondrial dynamics. In this review, we describe recent progress identifying novel protein and lipid components that regulate mitochondrial dynamics and emphasize clear gaps in our understanding of how mitochondrial dynamics are coordinated at MCSs. Finally, we conclude by discussing progress towards defining the highly biomedically relevant, but enigmatic, role of mitochondrial dynamics in the preservation of mitochondrial DNA integrity.

DOI: https://doi.org/10.1016/j.ceb.2025.102535
Biomedicines. 2025 May 09. pii: 1146. [Epub ahead of print]13(5):

Exploring Protein Misfolding in Amyotrophic Lateral Sclerosis: Structural and Functional Insights.

Ouliana Ivantsik, Themis P Exarchos, Aristidis G Vrahatis, Panagiotis Vlamos, Marios G Krokidis.

  Protein functionality depends on its proper folding, making protein misfolding crucial for the function of proteins and, by extension, cells and the whole organism. Increasing evidence supports the role of protein misfolding in the pathogenesis of neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS). ALS is a rapidly progressive disease diagnosed at a prevalence of 5 cases per 100,000, with approximately 2-3 patients per 100,000 diagnosed each year. To date, there is no cure, and the disease usually leads to death within 2 to 5 years from diagnosis. There are two types of the disorder: familial ALS (fALS), accounting for approximately 10% of cases, and sporadic (sALS), accounting for the remaining 90%. The hallmark of ALS, regardless of type, is the protein aggregates found in patients' tissues. This suggests that the disruption of proteostasis plays a critical role in the development of the disease. Herein, we stress the distinct factors that lead to protein misfolding and aggregate formation in ALS. Specifically, we highlight several triggering factors affecting protein misfolding, namely mutations, errors in the processes of protein production and trafficking, and failures of folding and chaperone machinery. Gaining a deeper understanding of protein aggregation will improve our comprehension of disease pathogenesis and potentially uncover new therapeutic approaches.

Keywords:  aggregation; amyotrophic lateral sclerosis; mutations; prion; protein misfolding; superoxide dismutase 1

DOI:  https://doi.org/10.3390/biomedicines13051146
Curr Opin Cell Biol. 2025 May 26. pii: S0955-0674(25)00077-8. [Epub ahead of print]95 102539

Actin in mitochondrial regulation and mechanometabolic crosstalk.

Peng Shi, Yuhan Zhang, Congying Wu.

Mitochondria undergo dynamic adaptations to cellular energy demands, changing morphology and function, through active interactions with other cellular organelles and the cytoskeletons. With advances in light and electron microscopy, actin probes for live-cell imaging, as well as proximity labeling, subtle and transient actin structures associated with mitochondria have been resolved and examined, which opened a new era for the understanding of architectural and mechanical regulation of organelles and metabolism. Here, we first review the recent findings that elucidate the actin-mitochondrion interactions in regulating mitochondrial dynamics (including fission, fusion and trafficking), and cristae architecture. Further, we discuss the functional consequences accompanying these morphological changes, which link cellular metabolism to the cytoskeleton and mechanotransduction through direct or indirect organelle control. Moreover, we summarize the avant-garde techniques for probing mitochondrion-associated actin, including new ways to visualize mitochondria-actin interaction in the cytosol and within the mitochondria, methods to identify the molecular components mediating actin-mitochondria crosstalk, and techniques for reconstructing the 3D ultrastructure of actin-mitochondrion interaction. Finally, we conclude pressing issues in this exciting field, calling for interdisciplinary efforts in examine actin-mitochondrion interactions at micro and macro levels. The dynamics and structural integrity of mitochondria are essential for energy metabolism and signal transduction, while their abnormalities lead to mitochondrial dysfunction and severe disease. This review aims to provide a comprehensive perspective on the emerging roles of the actin cytoskeleton in shaping mitochondrial morphology, structure, and functions, providing new angles to understand mitochondria-related diseases.

DOI: https://doi.org/10.1016/j.ceb.2025.102539
Antioxidants (Basel). 2025 May 20. pii: 611. [Epub ahead of print]14(5):

c-Abl/TFEB Pathway Activation as a Common Pathogenic Mechanism in Lysosomal Storage Diseases: Therapeutic Potential of c-Abl Inhibitors.

Miguel V Guerra, Juan Castro, Antonio Moreno, Elisa Balboa, Juan J Marugan, Alejandra R Alvarez, Silvana Zanlungo.

  Lysosomal storage diseases (LSDs) are characterized by the accumulation of undegraded substrates within lysosomes, often associated with oxidative stress and impaired lysosomal function. In this study, we investigate the role of the c-Abl/TFEB pathway in different LSDs: Gaucher, Niemann-Pick type A (NPA), and Niemann-Pick type C (NPC). Our findings identify c-Abl activation (p-c-Abl) as a common pathogenic mechanism in these disorders. We demonstrate that c-Abl phosphorylates TFEB at Tyr173, leading to its cytoplasmic retention. Using pharmacological models of Gaucher, NPA and NPC in SH-SY5Y neuronal cells and HeLa cells, we assess the effects of the c-Abl inhibitors Imatinib and Neurotinib, as well as the antioxidant α-Tocopherol (α-TOH), on TFEB nuclear translocation and p-c-Abl protein levels. Additionally, we explore the effects of c-Abl inhibitors in cholesterol accumulation in LSDs neuronal models. Our results show that treatment with c-Abl inhibitors or α-TOH promotes TFEB nuclear translocation, enhances lysosomal clearance, and reduces cholesterol accumulation in all three LSD models. These findings highlight the c-Abl/TFEB pathway as a potential therapeutic target for LSDs and potentially other neurodegenerative disorders associated with lysosomal dysfunction.

Keywords:  Gaucher; Imatinib; Neurotinib; Niemann-Pick; c-Abl; lysosomal storage diseases; transcription factor EB; α-Tocopherol

DOI:  https://doi.org/10.3390/antiox14050611
Autophagy. 2025 May 25.

Endoplasmic reticulum tubule junctions are sites of autophagy.

Susan Ferro-Novick.

  Selective endoplasmic reticulum (ER) macroautophagy/autophagy, also called reticulophagy, is a disposal pathway that degrades ER domains. A major role of reticulophagy is the removal of ER domains that contain misfolded proteins resistant to ER-associated degradation (ERAD). Our studies have shown that RTN3L, the SEC24C-SEC23 COPII coat subcomplex, and the CUL3KLHL12 E3 ligase that ubiquitinates RTN3L targets ERAD-resistant misfolded protein condensates for degradation at ER-reticulophagy sites (ERPHS), autophagic sites that form at tubule junctions. Unexpectedly, we found that the Parkinson disease protein PINK1 regulates ER tubulation. Loss of PINK1 disrupts the formation of peripheral tubule junctions, and, as a consequence, reticulophagy is blocked and misfolded proteins accumulate in the ER. Overexpression of the ER tubulating domain of DNM1L/DRP1, a multifunctional PINK1 kinase substrate that localizes to ER-mitochondria contact sites, increases junctions and restores reticulophagy. Our findings show that PINK1 shapes the ER to target misfolded proteins for RTN3L-SEC24C-mediated macroreticulophagy at defined ER sites, peripheral tubule junctions.

Keywords:  ER junctions; ER quality control; Reticulophagy

DOI:  https://doi.org/10.1080/15548627.2025.2508934
Neuroscientist. 2025 May 29. 10738584251337664

Phosphoinositides: Nanoscale Effects on Neuronal Membranes.

Kohgaku Eguchi.

  Phosphoinositides (PIs) are essential regulators of neuronal function, playing pivotal roles in processes such as synaptic transmission, membrane excitability, and long-term synaptic plasticity. The seven PI isoforms, including PI(4)P, PI(4,5)P2, and PI(3,4,5)P2, exhibit distinct subcellular distributions that are tightly regulated by specific kinases and phosphatases. These isoforms contribute to key neuronal processes by modulating protein interactions and signaling pathways. Recent advances in visualization techniques, such as biosensor-based live imaging and SDS-digested freeze-fracture replica labeling, have provided new insights into the spatial distributions and dynamic behaviors of PI isoforms in neurons, particularly at synapses.However, significant questions remain, such as how specific PI isoforms coordinate signaling events in distinct subcellular compartments and how these lipids influence critical neuronal processes like vesicular trafficking and synaptic plasticity. Addressing these challenges will require the continued development of advanced imaging technologies, which are essential for mapping nanoscale distributions of PIs and their dynamic roles in neuronal processes. Here, I will review current findings, advancements in visualization methodologies, and key research directions. This review will be helpful for understanding the roles of PIs in neuronal physiology, their broad impacts on neuronal signaling, and the technological breakthroughs needed to uncover these complex processes.

Keywords:  electron microscopy; live imaging; neuron; phosphoinositide; phospholipid; synapse

DOI:  https://doi.org/10.1177/10738584251337664
Biomolecules. 2025 May 16. pii: 728. [Epub ahead of print]15(5):

Recovery of Lysosomal Acidification and Autophagy Flux by Attapulgite Nanorods: Therapeutic Potential for Lysosomal Disorders.

Yuanjing Hao, Xinru Fan, Xiaodan Huang, Zhaoying Li, Zhiyuan Jing, Guilong Zhang, Yuxue Xu, Na Zhang, Pengfei Wei.

  Dysfunction of the lysosome and autophagy-lysosome pathway is closely associated with various diseases, such as neurodegenerative diseases, non-alcoholic fatty liver disease (NAFLD), etc. Additionally, chloroquine is a clinically widely used drug for treating malaria and autoimmune diseases, but long-term or high-dose administration may lead to significant toxic side effects. Attapulgite (ATT), a natural nanomaterial with excellent adsorption capacity and biocompatibility, herein demonstrated a novel biological function in regulating the lysosomal and autophagy-lysosome pathway. ATT could be effectively internalized into lysosome-related acidic compartments. Further study revealed that ATT could restore lysosomal pH, activate cathepsin D, alleviate autophagy blockage in chloroquine-treated cells, and reduce chloroquine-elicited cell death. In a cell model related to Huntington's disease, treatment with ATT reinforced the degradation of the mutant huntingtin proteins by increasing cathepsin D maturation and autophagy flux. ATT could also promote lipid droplet clearance in hepatocytes with palmitic acid-induced steatosis, reduce hepatic lipid accumulation, and improve fasting blood glucose in high-fat-diet-induced NAFLD mice. These findings establish ATT as a lysosomal modulator, providing a foundation for its therapeutic potential in mitigating the adverse effects associated with long-term chloroquine use, especially improving neurodegenerative and metabolic disorders.

Keywords:  attapulgite; autophagy flux; lysosomes; mutant huntingtin; neurodegenerative diseases; non-alcoholic fatty liver disease

DOI:  https://doi.org/10.3390/biom15050728
PLoS One. 2025 ;20(5): e0323953

Screening for variable drug responses using human iPSC cohorts.

Melpomeni Platani, Hao Jiang, Lindsay Davidson, Santosh Hariharan, Regis Doyonnas, Angus I Lamond, Jason R Swedlow.

We have developed a laboratory-based drug screening platform that uses a cohort of human induced pluripotent stem cell (hiPSC) lines, derived from different donors, to predict variable drug responses of potential clinical relevance. This builds on recent findings that pluripotent hiPSC lines express a broad repertoire of gene transcripts and proteins, whose expression levels reflect the genetic identity of the donor. We demonstrate that a cohort of hiPSC lines from different donors can be screened efficiently in their pluripotent state, using high-throughput Cell Painting assays. Variable phenotypic responses between hiPSC lines were detected with a wide range of clinically approved drugs, in use across multiple disease areas. Furthermore, information on mechanisms of drug-cell interactions underlying the observed variable responses was derived by using quantitative proteomic analysis to compare sets of hiPSC lines that had been stratified objectively, based upon variable response, Cell Painting data. We propose that information derived from comparative drug screening, using curated libraries of hiPSC lines from different donors, can help to improve the delivery of safe new drugs suitable for a broad range of genetic backgrounds and sexual diversity within human populations.

DOI: https://doi.org/10.1371/journal.pone.0323953
Sci Rep. 2025 May 27. 15(1): 18542

An optimized method for directed differentiation of hypothalamic neural stem cells in a 3D culture system.

Jiao Luo, Qiaoyan Tang, Tanjing Lin, Jiabang Liu, Zhiheng Wu, Xintao Zhang, Xiaohua Zhang, Junhai Jiang, Yulong Wang.

  Hypothalamic neurogenesis is a complex process that plays a crucial role in neuroendocrine homeostasis, making in vivo studies of the hypothalamus particularly challenging. In this study, we present an optimized protocol for isolating and culturing hypothalamic neural stem cells (htNSCs) from neonatal (P1) mice, followed by their directed differentiation in a three-dimensional (3D) Matrigel environment. We successfully established a primary culture system that supports the stability, growth, and distinct characteristics of htNSCs. Notably, we demonstrate that htNSCs can differentiate into GnRH-like neurons within the Matrigel-based 3D culture system. These differentiated neurons exhibit typical neuronal morphology and functional characteristics. Our findings highlight the potential of neonatal htNSCs as an invaluable model for studying hypothalamic function and neurogenesis. Furthermore, this method provides a novel platform for basic research and may serve as important implications for further studying the pathological mechanism of neuroendocrine disorders in hypothalamus.

Keywords:  GnRH neuron; Hypothalamic neural stem cells (htNSCs); Neonatal mice; Neuronal differentiation; Three-dimensional culture

DOI:  https://doi.org/10.1038/s41598-025-02847-6
J Biol Chem. 2025 May 24. pii: S0021-9258(25)02142-8. [Epub ahead of print] 110292

UPS10 inhibits the degradation of α-synuclein, a pathogenic factor associated with Parkinson's disease, by inhibiting chaperone-mediated autophagy.

Sergei Anisimov, Masahiko Takahashi, Taichi Kakihana, Yoshinori Katsuragi, Junya Sango, Takayuki Abe, Masahiro Fujii.

  Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by loss of dopaminergic neurons, particularly in the substantia nigra of the brain. α-Synuclein is a major causative factor in both familial and sporadic forms of PD, and its protein aggregates play critical roles in neuronal cell death and PD pathogenesis. This study explored the role of ubiquitin-specific protease 10 (USP10) in the regulation of α-synuclein in neuronal cells. Knockdown of USP10 (USP10-KD) in SH-SY5Y neuronal cells led to a reduction in α-synuclein levels, which was reversed by inhibiting chaperone-mediated autophagy (CMA) through LAMP2A depletion, a protein essential for CMA. A novel CMA reporter with a specific CMA degradation motif further demonstrated that USP10-KD activated CMA in neuronal cells. In addition, USP10 overexpression increased the levels of both wild-type and five PD-associated α-synuclein mutants, whereas a deubiquitinase-deficient USP10 mutant did not increase α-synuclein levels. This study provides new insights into the mechanisms that regulate α-synuclein proteostasis and highlights USP10 as a promising drug target for PD.

Keywords:  Parkinson’s disease; USP10; α-synuclein; сhaperone-mediated autophagy

DOI:  https://doi.org/10.1016/j.jbc.2025.110292
Cells. 2025 05 09. pii: 684. [Epub ahead of print]14(10):

Intracellular Inclusions Induced by Patient-Derived and Amplified α-Synuclein Aggregates Are Morphologically Indistinguishable.

Rabab Al-Lahham, Mark E Corkins, Mohd Ishtikhar, Prakruti Rabadia, Santiago Ramirez, Victor Banerjee, Mohammad Shahnawaz.

  Lewy Body Disease (LBD) and Multiple System Atrophy (MSA) are synucleinopathies with distinct prognoses and neuropathologies, however, with overlapping clinical symptoms. Different disease characteristics are proposed to be determined by distinct conformations of alpha-synuclein (α-Syn) aggregates, which can self-propagate and spread between cells via a prion-like mechanism. The goal of this study is to investigate whether α-syn aggregates amplified from brain and CSF samples of LBD and MSA patients using the Seed Amplification Assay (SAA) maintain α-Syn seeding properties similar to those of α-syn aggregates derived from patients' brains. To address this, SAA-amplified and un-amplified α-Syn aggregates from LBD and MSA patients' brains, as well as SAA-amplified α-Syn aggregates from LBD and MSA patients' CSF samples, were used to treat synuclein biosensor cells, and induced intracellular α-Syn inclusions were analyzed by confocal microscopy. Our data indicate that induced α-Syn aggregates from LBD and MSA patients' brains have similar seeding properties and morphological characteristics in the α-Syn biosensor cells as those amplified from LBD and MSA patients' brains, as well as those amplified from LBD and MSA patients' CSF samples. In this study, we demonstrated that, regardless of the source of aggregates, the seeds from LBD and MSA produce cellular accumulation of α-Syn with distinct morphologies, confirming the presence of different conformational strains of α-Syn in LBD and MSA and allowing us to differentiate synucleinopathies based on the morphology of aggregates and seeding properties.

Keywords:  Parkinson’s disease; SAA; aggregation; biosensor cells; multiple system atrophy; α-synuclein

DOI:  https://doi.org/10.3390/cells14100684
Mol Cell. 2025 May 23. pii: S1097-2765(25)00416-2. [Epub ahead of print]

Tunable metastability of condensates reconciles their dual roles in amyloid fibril formation.

Tapojyoti Das, Fatima K Zaidi, Mina Farag, Kiersten M Ruff, Tharun Selvam Mahendran, Anurag Singh, Xinrui Gui, James Messing, J Paul Taylor, Priya R Banerjee, Rohit V Pappu, Tanja Mittag.

  Stress granules form via co-condensation of RNA-binding proteins (RBPs) containing prion-like low-complexity domains (PLCDs) with RNA molecules. Homotypic interactions among PLCDs can drive amyloid fibril formation that is enhanced by amyotrophic lateral sclerosis (ALS)-associated mutations. We report that condensation- versus fibril-driving homotypic interactions are separable for A1-LCD, the PLCD of hnRNPA1. These separable interactions lead to thermodynamically metastable condensates and globally stable fibrils. Interiors of condensates suppress fibril formation, whereas interfaces have the opposite effect. ALS-associated mutations enhance the stability of fibrils and weaken condensate metastability, thus enhancing the rate of fibril formation. We designed mutations to enhance A1-LCD condensate metastability and discovered that stress granule disassembly in cells can be restored even when the designed variants carry ALS-causing mutations. Therefore, fibril formation can be suppressed by condensate interiors that function as sinks. Condensate sink potentials are influenced by their metastability, which is tunable through separable interactions even among minority components of stress granules.

Keywords:  RNP granule; amyotrophic lateral sclerosis; fibril formation; frontotemporal dementia; metastability; phase separation; prion-like domain; sink potential; stress granule; supersaturation

DOI:  https://doi.org/10.1016/j.molcel.2025.05.011
J Extracell Vesicles. 2025 Jun;14(6): e70100

Glutamatergic Regulation of miRNA-Containing Intraluminal Vesicle Trafficking and Extracellular Vesicle Secretion From Cortical Neurons.

Marcela Bertolio, Qiyi Li, Francesca E Mowry, Kathryn E Reynolds, Rashed Alananzeh, Haichao Wei, Kyoeun Keum, Rachel Jarvis, Jiaqian Wu, Yongjie Yang.

  Neuronal extracellular vesicles (microvesicles and exosomes) are emerging secreted vesicular signals that play important roles in the CNS. Currently, little is known about how glutamatergic signalling affects the subcellular localisation of exosome precursor intraluminal vesicles (ILVs), microRNA (miR) packaging into ILVs and in vivo spreading of neuronal EVs. By selectively labelling ILVs and exosomes (but not plasma membrane-derived MVs) with GFP-tagged human CD63 (hCD63-GFP) in cortical neurons, we found that glutamate stimulation significantly redistributes subcellular localisation of hCD63-GFP+ ILVs, especially decreasing its co-localisation with multi-vesicular body (MVB) marker Rab7 while substantially promoting EV secretion. Interestingly, glutamate stimulation only modestly alters EV miR profiles based on small RNA sequencing. Subsequent in vivo cortical neuronal DREADD activation leads to significantly more widespread hCD63-GFP+ area in hCD63-GFPf/+ mice, consistently supporting the stimulatory effect of glutamatergic activation on neuronal EV secretion and spreading. Moreover, in situ localisation of hCD63-GFP+ ILVs and hCD63-GFP+ secreted exosomes from specialised HB9+ and DAT+ neurons were also illustrated in the CNS. Taken together, our results demonstrated that glutamate activity stimulates neuronal exosome secretion and spreading in vitro and in vivo, but only modestly affects miR cargo packaging in neuronal exosomes.

Keywords:  CD63; extracellular vesicles; glutamate stimulation; intraluminal vesicles (ILVs); microRNA

DOI:  https://doi.org/10.1002/jev2.70100
Elife. 2025 May 30. pii: RP93621. [Epub ahead of print]13

Inhibition of mitochondrial protein import and proteostasis by a pro-apoptotic lipid.

Josep Fita-Torró, José Luis Garrido-Huarte, Lucía López-Gil, Agnès H Michel, Benoit Kornmann, Amparo Pascual-Ahuir, Markus Proft.

  Mitochondria-mediated cell death is critically regulated by bioactive lipids derived from sphingolipid metabolism. The lipid aldehyde trans-2-hexadecenal (t-2-hex) induces mitochondrial dysfunction from yeast to humans. Here, we apply unbiased transcriptomic, functional genomics, and chemoproteomic approaches in the yeast model to uncover the principal mechanisms and biological targets underlying this lipid-induced mitochondrial inhibition. We find that loss of Hfd1 fatty aldehyde dehydrogenase function efficiently sensitizes cells for t-2-hex inhibition and apoptotic cell death. Excess of t-2-hex causes a profound transcriptomic response with characteristic hallmarks of impaired mitochondrial protein import, like activation of mitochondrial and cytosolic chaperones or proteasomal function and severe repression of translation. We confirm that t-2-hex stress induces rapid accumulation of mitochondrial pre-proteins and protein aggregates and subsequent activation of Hsf1- and Rpn4-dependent gene expression. By saturated transposon mutagenesis, we find that t-2-hex tolerance requires an efficient heat shock response and specific mitochondrial and ER functions and that mutations in ribosome, protein, and amino acid biogenesis are beneficial upon t-2-hex stress. We further show that genetic and pharmacological inhibition of protein translation causes t-2-hex resistance, indicating that loss of proteostasis is the predominant consequence of the pro-apoptotic lipid. Several TOM subunits, including the central Tom40 channel, are lipidated by t-2-hex in vitro and mutation of accessory subunits Tom20 or Tom70 confers t-2-hex tolerance. Moreover, the Hfd1 gene dose determines the strength of t-2-hex mediated inhibition of mitochondrial protein import, and Hfd1 co-purifies with Tom70. Our results indicate that the transport of mitochondrial precursor proteins through the outer mitochondrial membrane is sensitively inhibited by the pro-apoptotic lipid and thus represents a hotspot for pro- and anti-apoptotic signaling.

Keywords:  S. cerevisiae; apoptosis; biochemistry; chemical biology; genetics; genomics; lipid signaling; mitochondrial protein import; proteostasis; sphingolipid metabolism; yeast

DOI:  https://doi.org/10.7554/eLife.93621
Commun Biol. 2025 May 30. 8(1): 838

Loss of UBE3A impacts both neuronal and non-neuronal cells in human cerebral organoids.

R Chris Estridge, Z Begum Yagci, Dilara Sen, Tyler J Johnson, Gautami R Kelkar, Travis S Ptacek, Jeremy M Simon, Albert J Keung.

Angelman syndrome is a neurodevelopmental disorder caused by (epi)genetic lesions of maternal UBE3A. Research has focused largely on the role of UBE3A in neurons due to its imprinting in that cell type. Yet, evidence suggests there may be broader neurodevelopmental impacts of UBE3A dysregulation. Human cerebral organoids might reveal these understudied aspects of UBE3A as they recapitulate diverse cell types of the developing human brain. In this study, scRNAseq on organoids reveals the effects of UBE3A disruption on cell type-specific compositions and transcriptomic alterations. In the absence of UBE3A, progenitor proliferation and structures are disrupted while organoid composition shifts away from proliferative cell types. We observe impacts on non-neuronal cells, including choroid plexus enrichment. Furthermore, EMX1+ cortical progenitors are negatively impacted; potentially disrupting corticogenesis and delaying excitatory neuron maturation. This work reveals impacts of UBE3A on understudied cell types and related neurodevelopmental processes and elucidates potential therapeutic targets.

DOI: https://doi.org/10.1038/s42003-025-08262-x
Cells. 2025 05 20. pii: 749. [Epub ahead of print]14(10):

Extracellular Vesicles in the Crosstalk of Autophagy and Apoptosis: A Role for Lipid Rafts.

Agostina Longo, Valeria Manganelli, Roberta Misasi, Gloria Riitano, Tuba Rana Caglar, Elena Fasciolo, Serena Recalchi, Maurizio Sorice, Tina Garofalo.

  Autophagy and apoptosis are two essential mechanisms regulating cell fate. Although distinct, their signaling pathways are closely interconnected through various crosstalk mechanisms. Lipid rafts are described to act as both physical and functional platforms during the early stages of autophagic and apoptotic processes. Only recently has a role for lipid raft-associated molecules in regulating EV biogenesis and release begun to emerge. In particular, lipids of EV membranes are essential components in conferring stability to these vesicles in different extracellular environments and/or to facilitate binding or uptake into recipient cells. In this review we highlight these aspects, focusing on the role of lipid molecules during apoptosis and secretory autophagy pathways. We describe the molecular machinery that connects autophagy and apoptosis with vesicular trafficking and lipid metabolism during the release of EVs, and how their alterations contribute to the development of various diseases, including autoimmune disorders and cancer. Overall, these findings emphasize the complexity of autophagy/apoptosis crosstalk and its key role in cellular dynamics, supporting the role of lipid rafts as new therapeutic targets.

Keywords:  apoptosis; autophagy; exosomes; extracellular vesicles; lipid rafts

DOI:  https://doi.org/10.3390/cells14100749
Nat Commun. 2025 May 27. 16(1): 4909

Restoring calcium crosstalk between ER and mitochondria promotes intestinal stem cell rejuvenation through autophagy in aged Drosophila.

Yao Zhang, Peng Ma, Saifei Wang, Shuxin Chen, Hansong Deng.

Breakdown of calcium network is closely associated with cellular aging. Previously, we found that cytosolic calcium (CytoCa2+) levels were elevated while mitochondrial calcium (MitoCa2+) levels were decreased and associated with metabolic shift in aged intestinal stem cells (ISCs) of Drosophila. How MitoCa2+ was decoupled from the intracellular calcium network and whether the reduction of MitoCa2+ drives ISC aging, however, remains unresolved. Here, we show that genetically restoring MitoCa2+ can reverse ISC functional decline and promote intestinal homeostasis by activating autophagy in aged flies. Further studies indicate that MitoCa2+ and Mitochondria-ER contacts (MERCs) form a positive feedback loop via IP3R to regulate autophagy independent of AMPK. Breakdown of this loop is responsible for MitoCa2+ reduction and ISC dysfunction in aged flies. Our results identify a regulatory module for autophagy initiation involving calcium crosstalk between the ER and mitochondria, providing a strategy to treat aging and age-related diseases.

DOI: https://doi.org/10.1038/s41467-025-60196-4
Mol Cell Neurosci. 2025 May 22. pii: S1044-7431(25)00022-3. [Epub ahead of print] 104012

A potential role for NADPH oxidase (NOX1/2) in mutant huntingtin-induced anomalous neurite outgrowth.

Luisana Duque Villegas, Alberte Vad Mathiesen, Izabela Rasmussen, Maria von Broich, Fillippa Liliendahl Qvist, Niels Skotte, Costanza Ferrari Bardile, Esben Budtz-Jørgensen, Kristine Freude, Benjamin Schmid, Mahmoud A Pouladi, Anne Nørremølle, Frederik Vilhardt.

  Neurite growth is regulated by NADPH Oxidase (NOX1 and 2) and in this study, we investigate whether neuritic abnormalities observed in stem cell models of Huntington's disease relates to altered NOX function during NGF-driven differentiation of PC12 neuronal cells. NOX1 and 2 were contained in separate vesicular compartments, and by overexpression inhibited or promoted neurite extension, respectively. Expression of mutant Htt (mHtt; exon 1 fragment) accelerated neuronal induction causing longer neurites in the first phase of differentiation, but fewer and shorter mature neurites. Htt/mHtt increased NOX2 protein levels but did not change global oxidant production; However, Htt/mHtt prominently redistributed NOX activity to neurites. Oxidant production was concentrated in intraluminal vesicles in multivesicular bodies, and mHtt specifically increased secretion of NOX1 in exosomes, which demonstrated oxidant production capacity, while rerouting NOX2 to lysosomal degradation. Knockdown of TSG101, required for intraluminal vesicle formation, increased cellular levels of NOX2/p22phox and neurite growth. Our study provides new insights on the disposition of NOX enzymes in nerve cells, indicating that deficient neurites in HD may be a correlate of altered trafficking, distribution, and activity of NOX.

Keywords:  ESCRT; Exosome; Huntington's disease; NADPH oxidase; NOX1; NOX2; Neurite outgrowth

DOI:  https://doi.org/10.1016/j.mcn.2025.104012
Biochem Soc Trans. 2025 May 29. pii: BST20253013. [Epub ahead of print]

Mechanisms of heme transport in the mitochondria.

Saieeda Fabia Ali, Adrianna E White, Amy Medlock, Oleh Khalimonchuk.

  Heme is a vital but highly reactive compound that is synthesized in mitochondria and subsequently distributed to a variety of subcellular compartments for utilization. The transport of heme is essential for normal cellular metabolism, growth, and development. Despite the vital importance of heme transport within the cell, data are lacking about how newly synthesized heme is shuttled within the mitochondrion or exported from the organelle. Here, we briefly summarize current knowledge about the process of mitochondrial heme distribution and discuss the current unresolved questions pertinent to this process.

Keywords:  heme; heme biosynthesis; hemoproteins; membrane transporters; mitochondria

DOI:  https://doi.org/10.1042/BST20253013
Curr Opin Neurobiol. 2025 May 24. pii: S0959-4388(25)00085-6. [Epub ahead of print]93 103054

Macroautophagy at the service of synapses.

Erin Wosnitzka, Lisa Gambarotto, Vassiliki Nikoletopoulou.

Post-mitotic and highly polarized neurons are dependent on the fitness of their synapses, which are often found a long distance away from the soma. How the synaptic proteome is maintained, dynamically reshaped, and continuously turned over is a topic of intense investigation. Autophagy, a highly conserved, lysosome-mediated degradation pathway has emerged as a vital component of long-term neuronal maintenance, and now more specifically of synaptic homeostasis. Here, we review the most recent findings on how autophagy undergoes both dynamic and local regulation at the synapse, and how it contributes to pre- and post-synaptic proteostasis and function. We also discuss the insights and open questions that this new evidence brings.

DOI: https://doi.org/10.1016/j.conb.2025.103054
Opt Lett. 2025 Jun 01. 50(11): 3529-3532

Three-dimensional super-resolution imaging of whole cells using a high numerical aperture oblique-plane microscope.

Zhuoli Ding, Xian'ao Zhao, Lei Wang, Shihang Luo, Tianjie Yang, Chunyan Fan, Jing Lu, Shun Xiong, Weixing Li, Tao Xu, Lusheng Gu, Wei Ji.

We present HOPE-STORM, a high-numerical-aperture oblique-plane microscope enabling whole-cell super-resolution imaging with an effective NA of 1.40. The system is compatible with DNA-PAINT, resolving nuclear pore complex (NPC) structures at 7.5 nm. We demonstrate dual-color super-resolution imaging of intact cells and, for the first time, to our knowledge, quantify the 3D organization of dynamin-related protein 1 (DRP1) complexes at mitochondrial fission sites. Our findings provide structural insights into DRP1 dynamics and mitochondrial fission mechanisms.

DOI: https://doi.org/10.1364/OL.550216
Sci Adv. 2025 May 30. 11(22): eadq6477

Dynamic regulation of vesicle pools in a detailed spatial model of the complete synaptic vesicle cycle.

Andrew R Gallimore, Iain Hepburn, Svilen V Georgiev, Silvio O Rizzoli, Erik De Schutter.

Synaptic transmission is driven by a complex cycle of vesicle docking, release, and recycling, maintained by distinct vesicle pools. However, the partitioning of vesicle pools and reserve pool recruitment remain poorly understood. We use a novel vesicle modeling technology to model the synaptic vesicle cycle in unprecedented molecular and spatial detail at a hippocampal synapse. Our model demonstrates robust recycling of synaptic vesicles that maintains consistent synaptic release, even during sustained high-frequency firing. We also show how the cytosolic proteins synapsin-1 and tomosyn-1 cooperate to regulate recruitment of reserve pool vesicles during sustained firing to maintain transmission, as well as the potential of selective vesicle active zone tethering to ensure rapid vesicle replenishment while minimizing reserve pool recruitment. We also monitored vesicle usage in isolated hippocampal neurons using pH-sensitive pHluorin, demonstrating that reserve vesicle recruitment depends on firing frequency, even at nonphysiologically high firing frequencies, as predicted by the model.

DOI: https://doi.org/10.1126/sciadv.adq6477
Mol Biol Rep. 2025 May 29. 52(1): 515

Aging-induced alterations in microglial cells and their impact on neurodegenerative disorders.

Hridaya Singh, Rahul Gupta, Madhu Gupta, Ausaf Ahmad.

  Senescence causes deterioration in the functioning and physiology of an organism. Microglia, the standing resident immune brain cells transform from neuroprotective to neurotoxic with age. Rapid process motility and cellular migration of microglia in the developing brain, and other characteristics are regarded to be crucial for immunological defense and tissue repair. As they mature, microglia not only differ in their morphology but also in their functioning. However, the exact mechanism related to the atrophies caused by aged microglia or their role in neurodegenerative diseases is still uncertain. The aim of this updated review is to provide insights of how aging microglial cells change and how this influences the development of neurodegenerative diseases. As life expectancy rises, there is an increase in the accumulation of iron, ROS/NOS, protein misfolding and insufficient clearing of debris. This is attributed to the age-dependent alterations in the genes linked to energy metabolism, mitochondrial and lysosome function, and neuroinflammation. Aging microglia often shifts towards a pro-inflammatory state with a reduction of anti-inflammatory cytokines. Aging microglia fail to clear amyloid-beta plaques, accelerates tau-pathology and enhances the chronic neuroinflammation, exacerbating the α-synuclein aggregation. These changes significantly impacted the onset of various neurogenerative disorders such as amyotrophic lateral sclerosis, Parkinson's disease, and Alzheimer's disease etc. However, it is important to note that these microglial aging effects might not be perceived as absolute, due to various limitations such as microglial heterogeneity, intercellular complexity across brain regions and variability in human aging owing to genetic and epigenetic variations. Regardless of this the future perspective of such insights are of immense relevance as novel therapeutic approaches can be formulated if the molecular and cellular mechanisms of aging microglial perturbations are understood. Future research should focus on restoring microglial homeostasis to mitigate the effects of aging on the brain and slowing the progression of neurodegenerative diseases.

Keywords:  Aging; Microglial cells; Neurodegenerative diseases; Neuroinflammation

DOI:  https://doi.org/10.1007/s11033-025-10623-y
Biomolecules. 2025 Apr 29. pii: 637. [Epub ahead of print]15(5):

Ngn2-Induced Differentiation of the NG108-15 Cell Line Enhances Motor Neuronal Differentiation and Neuromuscular Junction Formation.

Madeline Meli, Kristy Swiderski, Jinchao Gu, Ben Rollo, Ben Bartlett, Marissa K Caldow, Gordon S Lynch, Patrick Kwan, Huseyin Sumer, Brett Cromer.

  The neuronal progenitor NG108-15 neuroblastoma x glioma cell line proliferates indefinitely in vitro and is capable of directed differentiation into cholinergic neurons. The cell line is a robust model for investigating neuronal differentiation and function in vitro. The lineage-specific transcription factor-mediated differentiation of pluripotent stem cell lines (PSCs) leads to more rapid, efficient, and functional neurons. In this study, we tested the hypothesis that transcription factors could also drive the fate of an immortalised cell line. We first established a stable NG108-15 cell line, by piggyBac (pBac) transposition, that conditionally expresses neurogenin-2 (Ngn2), a common transcription factor for specifying neuronal fate. Following doxycycline-induction of Ngn2, we observed more rapid and efficient differentiation, and improved neurite outgrowth and viability compared with the WT cell line. Moreover, when co-cultured with C2C12 mouse myotubes, the modified NG108-15 cells resulted in significantly larger acetylcholine receptor (AChR) aggregates, suggesting enhanced neuromuscular junction (NMJ) formation. These findings describe a novel methodology for differentiating NG108-15 cells more efficiently, to enhance the usefulness of the cell line as a motor neuron model.

Keywords:  cell differentiation; cell line; motor neurons; muscle fibres; myogenesis; neuroblastoma; neuromuscular junction; neurons; skeletal muscle; transcription factors

DOI:  https://doi.org/10.3390/biom15050637
Genes Brain Behav. 2025 Jun;24(3): e70023

Vitamin C Transport Deficiency Alters Striatal Dopamine Gene Expression and Metabolism in YAC128 Huntington Disease Mice.

Adriana A Tienda, Fiona E Harrison, Jordyn M Wilcox.

  Neurodegeneration in Huntington disease (HD) contributes to dopaminergic system dysfunction via the loss of striatal medium spiny neurons expressing dopamine receptors. Given the key role for ascorbic acid (vitamin C) in dopamine synthesis and neurotransmission, we investigated whether mild cellular ascorbate deficiency accelerates dopaminergic dysfunction in the development of HD pathology and behavioral deficits. YAC128 mice expressing mutant human huntingtin were crossed with SVCT2+/- mice, which carry a heterozygous knockout of the sodium-dependent vitamin C transporter, to generate mice with approximately 30% decreased neuronal vitamin C as well as progressive changes in dopamine signaling. Behavioral and neurochemical outcomes were assessed at early disease stages. At 14 and 20 weeks, YAC128 and SVCT2+/- YAC128 mice showed similar deficits in grip strength, locomotor activity, and rotarod performance compared to controls, suggesting modest ascorbate deficiency did not accelerate motor phenotypes. Gene expression analysis revealed six significantly upregulated genes in the striatum of SVCT2+/- YAC128 mice, including those involved in dopamine synthesis, packaging, and transport. Notably, striatal dopamine and serotonin and their metabolites were decreased in both single mutant mouse lines (YAC128 and SVCT2+/-) but without a compounding effect of the double mutation (SVCT2+/- YAC128). These results indicate that while moderate ascorbate deficiency may not worsen early behavioral phenotypes in the YAC128 model, it does impact dopamine system regulation at the molecular level. These findings highlight the potential importance of ascorbate in modifying disease progression and suggest that humans with HD, who cannot synthesize ascorbate, may be particularly vulnerable to vitamin C deficiency effects on dopamine dynamics.

Keywords:  Huntington's disease; SVCT2; ascorbic acid; dopamine; mouse behavior

DOI:  https://doi.org/10.1111/gbb.70023
Histochem Cell Biol. 2025 May 28. 163(1): 61

Microtubule nucleation at the Golgi-related membrane organelles of mouse neurons.

Haruki Kasai, Kensuke Hayashi.

  Microtubules are often nucleated at non-centrosomal sites in some differentiated cell types. We previously reported that microtubules are nucleated at the cytoplasm in cultured mouse cortical neurons. It is unclear, however, what organelle is the site of such nucleation. In this study, we examined the possibility that recently discovered neuron-specific Golgi-like structures called Golgi satellites are the nucleation sites. Microtubule nucleation was tested by observing microtubule regrowth after nocodazole depolymerization. First, the spatial association between microtubule nucleation and membrane organelles was investigated. Organelle markers including GM130 (cis Golgi and Golgi outpost marker), Golgin97 (trans-Golgi network marker), transferrin receptor (recycling endosome marker), TOMM40 (mitochondria marker), and syntaxin 6 (early endosome and Golgi satellite marker) were examined. Microtubule regrowth was observed in cytoplasmic regions where TOMM40-positive and syntaxin 6-positive organelles were rich. Triple immunostaining showed that γ-tubulin at one end of regrown microtubules was attached to syntaxin 6-organelles but not to TOMM40-organelles, indicating that syntaxin 6-organelles are the microtubule nucleation sites. To address the possibility that the microtubule-nucleating syntaxin 6-organelles were Golgi satellites, we transfected neurons with plasmid vector caring FLAG-tagged Golt sequence, a marker for Golgi satellites, and subsequently performed microtubule regrowth experiments. We found regrown microtubules on FLAG-positive organelles in dendrites. This observation suggests that Golgi satellites are microtubule nucleation sites. Microtubules from the Golgi satellites might guide transport vesicles generated at rough endoplasmic reticulum in dendrites.

Keywords:  Dendrite; Golgi apparatus; Golgi satellite; MTOC; Microtubule nucleation

DOI:  https://doi.org/10.1007/s00418-025-02390-5