bims-axbals 2025-08-31 papers

bims-axbals

Biomed News

on Axonal biology and ALS

Issue of 2025–08–31
23 papers selected by
TJ Krzystek

Blueprint of Collapse: Precision Biomarkers, Molecular Cascades, and the Engineered Decline of Fast-Progressing ALS.
TARDBP (TDP-43) Knock-in Zebrafish Display a Late-Onset Motor Phenotype and Loss of Large Spinal Cord Motor Neurons.
Disrupted Myelination in FAHN: Insights from a Patient-Specific hiPSC Neuron-Oligodendrocyte Model.
CHIP protects lysosomes from CLN4 mutant-induced membrane damage.
An unrecognized mechanism of self-protection in degenerating neurons mediated by astrocytic YAP through Wnts/β-catenin/EAAT2 signaling in C9orf72-poly-GA mice.
An Elongator mouse model of ALS spotlights TDP-43 in the motor neuron nucleolus.
Soma-localized Rab39 inhibits synaptic autophagy by controlling trafficking of Atg9 vesicles.
Astrocyte-neuron combined targeting for CYP46A1 gene therapy in Huntington's disease.
Lysosomal polyamine storage upon ATP13A2 loss impairs β-glucocerebrosidase via altered lysosomal pH and electrostatic hydrolase-lipid interactions.
Astrocytes expressing mutant hnRNPA1 induce non-cell-autonomous motor neuron death.
Activation of polo-like kinase 1 correlates with selective motor neuron vulnerability in familial ALS.
ALS/FTD-linked TBK1 deficiency in microglia induces an aged-like microglial signature and drives social recognition deficits in mice.
Rho kinase isoforms in neurodegeneration: from cellular functions to therapeutic targets.
Mission cholesterol: Uncovering its hidden role in ALS neurodegeneration.
Dimer-Specific FokT-seq Reveals DNA-Binding Dimerization and Novel Genomic Targets of TDP-43.
During Aspergillus nidulans nitrogen-limited biofilm formation, mitophagy is independent of mitochondrial fission.
Cathepsins in Neurological Diseases.
DHX8 regulates degradation of RNA by RNautophagy.
Two specific interactions of GATE16 with TRPML3 and RAB33B regulate autophagy.
CDKL5 regulates the initiation of retrograde axonal transport through CLIP170-dynactin complex formation.
Molecular impact of antisense oligonucleotide therapy in C9orf72-associated ALS.
Elevated levels of Letm1 drives mitochondrial dysfunction and cardiomyocyte stress-mediated apoptosis in cultured cardiomyocytes.
Neurobiology of mitochondrial dynamics in sleep.

Int J Mol Sci. 2025 Aug 21. pii: 8072. [Epub ahead of print]26(16):

Blueprint of Collapse: Precision Biomarkers, Molecular Cascades, and the Engineered Decline of Fast-Progressing ALS.

Matei Șerban, Corneliu Toader, Răzvan-Adrian Covache-Busuioc.

  Amyotrophic lateral sclerosis (ALS) is still a heterogeneous neurodegenerative disorder that can be identified clinically and biologically, without a strong set of biomarkers that can adequately measure its fast rate of progression and molecular heterogeneity. In this review, we intend to consolidate the most relevant and timely advances in ALS biomarker discovery, in order to begin to bring molecular, imaging, genetic, and digital areas together for potential integration into a precision medicine approach to ALS. Our goal is to begin to display how several biomarkers in development (e.g., neurofilament light chain (NfL), phosphorylated neurofilament heavy chain (pNfH), TDP-43 aggregates, mitochondrial stress markers, inflammatory markers, etc.) are changing our understanding of ALS and ALS dynamics. We will attempt to provide a framework for thinking about biomarkers in a systematic way where our candidates are not signals alone but part of a tethered pathophysiological cascade. We are particularly interested in the fast progressor phenotype, a devastating and under-characterized subset of ALS due to a rapid axonal degeneration, early respiratory failure, and very short life span. We will try to highlight the salient molecular features of this ALS subtype, including SOD1 A5V toxicity, C9orf72 repeats, FUS variants, mitochondrial collapse, and impaired autophagy mechanisms, and relate these features to measurable blood and CSF (biomarkers) and imaging platforms. We will elaborate on several interesting tools, for example, single-cell transcriptomics, CSF exosomal cargo analysis, MRI techniques, and wearable sensor outputs that are developing into high-resolution windows of disease progression and onset. Instead of providing a static catalog, we plan on providing a conceptual roadmap to integrate biomarker panels that will allow for earlier diagnosis, real-time disease monitoring, and adaptive therapeutic trial design. We hope this synthesis will make a meaningful contribution to the shift from observational neurology to proactive biologically informed clinical care in ALS. Although there are still considerable obstacles to overcome, the intersection of a precise molecular or genetic association approach, digital phenotyping, and systems-level understandings may ultimately redefine how we monitor, care for, and treat this challenging neurodegenerative disease.

Keywords:  ALS fast progressors; C9orf72 repeat expansion; SOD1 A4V variant; TDP-43 aggregation; autophagy failure; digital phenotyping; mitochondrial dysfunction; neurofilament light chain; precision neurology; protein misfolding

DOI:  https://doi.org/10.3390/ijms26168072
Ann Neurol. 2025 Aug 27.

TARDBP (TDP-43) Knock-in Zebrafish Display a Late-Onset Motor Phenotype and Loss of Large Spinal Cord Motor Neurons.

Ziyaan A Harji, Christian J Rampal, Esteban C Rodríguez, Virginie Petel Légaré, Alexandra Lissouba, Sabrina Semmler, Meijiang Liao, Jay P Ross, Guy A Rouleau, Christine Vande Velde, Gary A B Armstrong.

OBJECTIVE: Mutations in TARDBP (encoding TDP-43) are associated with the neurodegenerative disease amyotrophic lateral sclerosis (ALS) and include familial missense mutations where there are a lack of models and mechanisms examining how they are pathogenic.
METHODS: In this study, we developed 2 tardbp (Tdp-43) knock-in (KI) zebrafish mutant models encoding the analogous A382T and G348C variants and investigated their degenerative phenotypes.
RESULTS: We show that both models display reduced survival as well as an age-dependent motor phenotype that manifests at 1.5 years. Both variants in either the heterozygous or homozygous state did not impact protein expression levels of Tdp-43 in the central nervous system. However, homozygous G347C zebrafish displayed reduced expression levels of the tardbp transcript. We observed muscle cell atrophy starting at 1 year of age and loss of large spinal cord motor neurons in both KI models in older fish (2.35-3 years of age). We did not observe Tdp-43 aggregates. However, we did observe increased cytoplasmic Tdp-43 localization in spinal cord motor neurons in A379T zebrafish. At 1 year of age, whole spinal cord RNA-sequencing revealed an upregulation of neuroinflammatory transcripts in both models, as well as the selective downregulation of transcripts involved with synaptic function in G347C zebrafish, including syn2a, syn2b, syt2a, and stxbp1a.
INTERPRETATION: These novel models of common TDP-43 disease variants provide a unique opportunity to further our understanding of neurodegeneration in vivo and demonstrate that mutations in the same protein and domain can manifest with different phenotypes. ANN NEUROL 2025.

DOI: https://doi.org/10.1002/ana.78012
Cells. 2025 Aug 15. pii: 1261. [Epub ahead of print]14(16):

Disrupted Myelination in FAHN: Insights from a Patient-Specific hiPSC Neuron-Oligodendrocyte Model.

Fatima Efendic, Andreas Hermann, Moritz J Frech.

  Fatty-acid-hydroxylase-associated neurodegeneration (FAHN) is a rare neurodegenerative disorder caused by loss-of-function mutations in the FA2H gene, leading to impaired enzymatic activity and resulting in myelin sheath instability, demyelination, and axonal degeneration. In this study, we established a human in vitro model using neurons and oligodendrocytes derived from induced pluripotent stem cells (hiPSCs) of a FAHN patient. This coculture system enabled the investigation of myelination processes and myelin integrity in a disease-relevant context. Analyses using immunofluorescence and Western blot revealed impaired expression and localisation of key myelin proteins in oligodendrocytes and cocultures. FA2H-deficient cells showed reduced myelination, shortened internodes, and disrupted formation of the nodes of Ranvier. Additionally, we identified autophagy defects-a hallmark of many neurodegenerative diseases-including reduced p62 expression, elevated LC3B levels, and impaired fusion of autophagosomes with lysosomes. This study presents a robust hiPSC-based model to study FAHN, offering new insights into the molecular pathology of the disease. Our findings suggest that FA2H mutations compromise both the structural integrity of myelin and the efficiency of the autophagic machinery, highlighting potential targets for future therapeutic interventions.

Keywords:  FA2H; FAHN; autophagy; demyelination; induced pluripotent stem cells; myelin proteins; neurons; oligodendrocytes

DOI:  https://doi.org/10.3390/cells14161261
Nat Cell Biol. 2025 Aug 25.

CHIP protects lysosomes from CLN4 mutant-induced membrane damage.

Juhyung Lee, Natalie Chin, Jizhong Zou, Wan Nur Atiqah Binti Mazli, Michal Jarnik, Layla Saidi, Yue Xu, Eutteum Jeong, Jessica Suh, John Replogle, Michael E Ward, Juan S Bonifacino, Wei Zheng, Ling Hao, Yihong Ye.

Understanding how cells mitigate lysosomal damage is critical for unravelling pathogenic mechanisms of lysosome-related diseases. Here we generate and characterize induced pluripotent stem cell (iPSC)-derived neurons (i3Neuron) bearing ceroid lipofuscinosis neuronal 4 (CLN4)-linked DNAJC5 mutations, which revealed extensive lysosomal abnormality in mutant neurons. In vitro membrane-damaging experiments establish lysosomal damages caused by lysosome-associated CLN4 mutant aggregates, as a critical pathogenic linchpin in CLN4-associated neurodegeneration. Intriguingly, in non-neuronal cells, a ubiquitin-dependent microautophagy mechanism downregulates CLN4 aggregates to counteract CLN4-associated lysotoxicity. Genome-wide CRISPR screens identify the ubiquitin ligase carboxyl terminus of Hsc70-interacting protein (CHIP) as a central microautophagy regulator that confers ubiquitin-dependent lysosome protection. Importantly, CHIP's lysosome protection function is transferrable: ectopic CHIP improves lysosomal function in CLN4 i3Neurons and effectively alleviates lipofuscin accumulation and cell death in a Drosophila CLN4 disease model. Our study establishes CHIP-mediated microautophagy as a key organelle guardian that preserves lysosome integrity, offering new insights into therapeutic development for lysosome-related neurodegenerative diseases.

DOI: https://doi.org/10.1038/s41556-025-01738-2
Theranostics. 2025 ;15(16): 8176-8201

An unrecognized mechanism of self-protection in degenerating neurons mediated by astrocytic YAP through Wnts/β-catenin/EAAT2 signaling in C9orf72-poly-GA mice.

Dongmei Li, Yan Wei, Rui Yang, Xuan Luo, Yanzhu Liu, Weiqiao Zhao, Hui Yang, Yumin Wu, Ying Wang, Zhihui Huang.

  Rationale: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the progressive loss of motor neurons in the central nervous system (CNS). Non-neuronal cells, particularly astrocytes, have been recognized as pivotal contributors to ALS onset and progression. However, the underlying mechanisms of interactions between astrocytes and motor neurons during ALS remain unclear. Recent studies have identified the neuronal Hippo kinase mammalian sterile 20-like kinase 1 (MST1) as a key regulator of neurodegeneration in ALS. Yes-associated protein (YAP), a major downstream effector of the Hippo pathway, is predominantly expressed in astrocytes. However, the role of astrocytic YAP in ALS and its underlying mechanisms remain unexplored. Methods: To evaluate the function of YAP in ALS, we established a C9orf72-poly-GA mouse model (ALS mice) via intracerebroventricular injection of AAV viruses. Furthermore, mice with conditional knockout (CKO) of YAP in astrocytes (YAPGFAP-CKO mice) were generated and then YAPGFAP-CKO ALS mice and their littermate controls (YAPf/f ALS mice) were used as experimental subjects. Behavioral tests, immunostaining, Nissl staining, quantitative real-time PCR (qPCR), and Western blotting were used to assess the effects of astrocytic YAP deletion in ALS progression. In addition, we investigated the role and mechanism of astrocytic YAP in the pathogenesis of ALS by integrating RNA sequencing (RNA-seq) from primary cultured astrocytes with single-nucleus transcriptomic (snRNA-seq) from C9orf72-ALS/FTD patients. Then, in vitro experiments including primary cultured astrocytes and neurons were used to further elucidate the potential molecular mechanism of astrocytic YAP in ALS. Finally, we evaluated the therapeutic effects of the excitatory amino acid transporter-2 (EAAT2) activator LDN-212320 and the Hippo kinase MST1/2 inhibitor XMU-MP-1 as candidate treatments for ALS. Results: We found that YAP was upregulated and activated specifically in astrocytes, but not in neurons or microglia, within the motor cortex of ALS mice. Conditional knockout of YAP in astrocytes exacerbated motor deficits, neuronal loss, pathological translocation of TDP-43, inflammatory infiltration, and reduced astrocytic proliferation in ALS mice. Mechanistically, Wnts secreted by degenerating neurons and astrocytes activated YAP/β-catenin signaling and further promoted the expression of EAAT2 in astrocytes, which prevented neuronal glutamate excitotoxicity, neuronal loss, and motor dysfunction in ALS mice. Interestingly, treatment with LDN-212320 promoted EAAT2 expression and partially restored motor deficits and neuronal loss in YAPGFAP-CKO ALS mice. Finally, activation of YAP by XMU-MP-1 upregulated β-catenin and EAAT2 expression, and partially alleviated motor deficits and neurodegeneration in ALS mice. Conclusions: These results identify an unrecognized mechanism of self-protection in degenerating neurons mediated by astrocytic YAP through Wnts/β-catenin/EAAT2 signaling to prevent glutamate excitotoxicity of neurons in ALS mice, and provide a novel drug target for ALS.

Keywords:  ALS; EAAT2; YAP; motor dysfunction; neurodegeneration

DOI:  https://doi.org/10.7150/thno.113599
Commun Biol. 2025 Aug 21. 8(1): 1259

An Elongator mouse model of ALS spotlights TDP-43 in the motor neuron nucleolus.

Magge Snow, BreAnna Cameron, Renzie Pond, Rachel Trudell, Sara Snyder, Lauryn Torres-Hernandez, Devyn Deschamps, Danara Tulimaiau, Kiana Hawkinson, Morgan Russell, Danielle Horan, Joseph Walters, James H Fox, Britni Arlian, Alain Chariot, Laurent Nguyen, Lynn George.

Dysfunction of Elongator is associated with amyotrophic lateral sclerosis (ALS). Here, we describe mouse models in which either Elongator subunit 1(Elp1) or subunit 3 (Elp3) is selectively ablated in alpha motor neurons of the spinal cord. These mice exhibit a progressive loss of motor strength and motor neuron degeneration. To interrogate the molecular mechanisms that contribute to motor neuron cell death in these mice, we examine multiple disease pathways, including the expression of TDP-43 whose cytoplasmic aggregation is associated with the human disease. Although TDP-43 is a well-characterized nuclear protein functioning in RNA metabolism and gene transcription, here we document TDP-43's robust presence in the nucleolus of wild-type motor neurons and its clearance from both the nucleus and the nucleolus of motor neurons in Elp conditional knockout mice. Thus, this study directly links dysfunction of Elongator with nucleolar disruption and TDP-43 clearing, two hallmark cellular pathologies of ALS.

DOI: https://doi.org/10.1038/s42003-025-08701-9
EMBO J. 2025 Aug 21.

Soma-localized Rab39 inhibits synaptic autophagy by controlling trafficking of Atg9 vesicles.

Ayse Kilic, Gokhan Ozturan, Dirk Vandekerkhove, Sabine Kuenen, Jef Swerts, Esther Muñoz Pedrazo, Carles Calatayud Aristoy, Abril Escamilla Ayala, Nikky Corthout, Pablo Hernández Varas, Stéphane Plaisance, Valerie Uytterhoeven, Eliana Nachman, Patrik Verstreken.

  Presynaptic terminals can be located far from the neuronal cell body and are thought to independently regulate protein and organelle turnover. Autophagy is a critical process for maintaining proteostasis, and its synaptic dysregulation is associated with neurodegenerative diseases. In this work, we report a soma-centered mechanism that regulates autophagy-controlled protein turnover at distant presynaptic terminals in Drosophila. We show that a central component of this system is Rab39, whose human homolog RAB39B is mutated in Parkinson's disease. Although Rab39 is localized in the soma, its loss of function or a human pathogenic mutation causes increased autophagy at presynaptic terminals, resulting in faster synaptic protein turnover and dopaminergic synapse degeneration. Using a large-scale unbiased genetic modifier screen, we identified genes encoding cytoskeletal and axonal organizing proteins, including Shortstop (Shot), as suppressors of synaptic autophagy. We demonstrate that active Rab39 selectively controls Shot- and Unc104/KIF1A-mediated delivery of autophagy-related Atg9-positive vesicles to synapses. Our findings suggest that Rab39-mediated trafficking in the soma orchestrates a cross-compartmental mechanism that regulates the levels of autophagy at synapses.

Keywords:   Drosophila ; Genetic Suppressor Screen; Parkinson’s Disease; Rab39; Synaptic Autophagy

DOI:  https://doi.org/10.1038/s44318-025-00536-8
Acta Neuropathol Commun. 2025 Aug 26. 13(1): 184

Astrocyte-neuron combined targeting for CYP46A1 gene therapy in Huntington's disease.

Louis-Habib Parsai, Farah Chali, Enejda Subashi, Caroline Zeitouny, Emilie Rey, A Berniard, William Bitton, Laureline Urli, Lisa Rousselot, Nadège Sarrazin, Véronique Blouin, Wilfried F A Den Dunnen, Kristin Michaelsen-Preusse, Martin Korte, Sandro Alves, Nathalie Cartier.

  Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by an abnormal expansion of cytosine-adenine-guanosine (CAG) trinucleotidein the huntingtin gene. Mutant huntingtin (mHTT) expression in neurons and glial cells affects neuron and astrocyte functions and leads to the loss of medium spiny neurons of the striatum. Brain cholesterol pathway is severely affected by HTT mutation in neurons and astrocytes, contributing to HD pathogenesis. Decreased cholesterol production and transport by astrocytes impair synapse maturation and neurotransmission. Brain cholesterol metabolism is maintained by cholesterol hydroxylation into 24-hydroxycholesterol by the neuronal enzyme cholesterol 24-hydroxylase (CYP46A1). CYP46A1 is decreased in affected brain regions in HD patients and mice. AAV-CYP46A1 striatal delivery was shown to restore cholesterol metabolism with neuroprotective effects in two mouse models of HD, characterized by mHTT aggregates' reduction, improved transcriptomic profile, and Brain-Derived Neurotrophic Factor (BDNF) signaling, and preservation of striatal neurons. From a therapeutic perspective, we intended to clarify the detailed mechanisms and the specific role of neurons and astrocytes in the therapeutic effects of AAV-CYP46A1 delivery. We first evaluated CYP46A1 expression in astrocytes in HD post-mortem putamen at a late stage of disease progression. To determine the specific contribution of CYP46A1 expression in astrocytes compared to neurons on the HD phenotype, we assessed the effects of AAV-CYP46A1 striatal injection under the control of astrocytic (GFA2) or neuronal (hSYN) promoters in R6/2 mice. Overall, equivalent transgenic CYP46A1 protein levels, both astrocytic and neuronal targeting, mitigate medium ppiny neuron (MSN) atrophy and improve spine density in R6/2 mice. Reduction of mHTT aggregates in neurons is similar when CYP46A1 is overexpressed in neurons or in astrocytes. However, astrocyte targeting reduces mHTT aggregates in neurons and astrocytes, while restricted neuronal targeting reduces mHTT aggregates in neurons only. Altogether, astrocytic targeting of CYP46A1 expression in CYP46A1-tested animals combines cell-autonomous and non-cell-autonomous mechanisms of action, with improved phenotypic correction compared to neuronal-restricted targeting. Allowing expression in both cell types with higher expression levels of CYP46A1 showed overall better efficacy. We demonstrate that astrocyte-neuron combined targeting with AAV-CAG-CYP46A1 delivery increases therapeutic efficacy. This study brings new evidence that CAG-mediated CYP46A1 striatal overexpression significantly modifies the transcriptome in R6/2 mice for pathways involved in synaptogenesis and inflammation, suggesting targeting both astrocytes and neurons provides benefits for HD phenotypic correction.

Keywords:  Astrocytes; Cholesterol; Inflammation; Neurons; Synapses

DOI:  https://doi.org/10.1186/s40478-025-02054-4
Cell Rep. 2025 Aug 22. pii: S2211-1247(25)00950-7. [Epub ahead of print]44(9): 116179

Lysosomal polyamine storage upon ATP13A2 loss impairs β-glucocerebrosidase via altered lysosomal pH and electrostatic hydrolase-lipid interactions.

Madhuja Samaddar, Gabriel A Fitzgerald, Ann Hong Nguyen, Sonnet S Davis, Shourya Jain, Jian Guo, Nicholas E Propson, Bettina van Lengerich, Yajuan Shi, Srijana Balasundar, Lionel Rougé, Jamal Alkabsh, Anil Rana, Julie Yi, Marcus Y Chin, Isabel A Becerra, Annie Arguello, Brian M Fox, Todd Logan, Jung H Suh, Anastasia G Henry, Gilbert Di Paolo.

  ATP13A2 is an endolysosomal polyamine transporter mutated in several neurodegenerative conditions involving lysosomal defects, including Parkinson's disease (PD). While polyamines are polybasic and polycationic molecules that play pleiotropic cellular roles, their specific impact on lysosomal health is unknown. Here, we demonstrate lysosomal polyamine accumulation in ATP13A2 knockout (KO) cell lines and human induced pluripotent stem cell (iPSC)-derived neurons. Primary polyamine storage caused secondary storage of lysosomal anionic phospholipid bis(monoacylglycero)phosphate (BMP) and an age-dependent increase in the β-glucocerebrosidase (GCase) substrate glucosylsphingosine in Atp13a2 KO brains. Polyamine accumulation inhibited lysosomal GCase activity in cells, and this was reversed by lysosome reacidification or BMP supplementation. A liposome-based GCase assay utilizing physiological substrates demonstrated dose-dependent inhibition of BMP-stimulated GCase activity by polyamines, in part via a pH-independent, electrostatics-based mechanism. Therefore, excess polyamine compromises lysosomes by disrupting pH and electrostatic interactions between GCase and BMP that enable efficient substrate hydrolysis, potentially clarifying pathogenic mechanisms and suggesting convergence on PD-relevant pathways.

Keywords:  CP: Neuroscience; Kufor-Rakeb syndrome; P-type ATPase; Parkinson’s disease; glucocerebrosidase; glycosphingolipid; lysosomal storage disorder; neuronal ceroid lipofuscinosis; polyamine; spermine

DOI:  https://doi.org/10.1016/j.celrep.2025.116179
Brain Res Bull. 2025 Aug 24. pii: S0361-9230(25)00334-X. [Epub ahead of print]230 111522

Astrocytes expressing mutant hnRNPA1 induce non-cell-autonomous motor neuron death.

Qinxue Wu, Xionghao Liu, Tingting Zhang, Shiquan Cui, Bo Huang, Cao Huang, Qilin Cao, Xu-Gang Xia, Hongxia Zhou.

  Pathogenic mutation of heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) is causative to amyotrophic lateral sclerosis (ALS). Neuron death resulting from pathogenic hnRNPA1 may not require its presence across all pertinent cells types, including neurons, glia, and muscles. Rather, the exclusive presence of pathogenic hnRNPA1 in a specific cell type, such as astrocytes, may suffice to substantially alter cellular functions. Consequently, this alteration initiates abnormal interaction within intricate neuron-glia networks, culminating in non-cell-autonomous motor neuron death. To investigate the pivotal role of non-cell-autonomous neuron death in hnRNPA1-associated ALS, we developed transgenic rats overexpressing mutant hnRNPA1 in specifically astrocytes. The confined overexpression of pathogenic hnRNPA1 in astrocytes instigated a sequence of events resulting in motor neuron death and subsequent muscle atrophy. These findings underscore the critical, non-cell-autonomous contribution of astrocytes to hnRNPA1-induced neurodegeneration in ALS, and point toward astrocytic pathways as potential therapeutic targets.

Keywords:  ALS; Astrocytes; HnRNPA1; Non-cell autonomous neuron death; Transgenic rats

DOI:  https://doi.org/10.1016/j.brainresbull.2025.111522
Cell Rep. 2025 Aug 25. pii: S2211-1247(25)00884-8. [Epub ahead of print]44(9): 116113

Activation of polo-like kinase 1 correlates with selective motor neuron vulnerability in familial ALS.

Barbara Szewczyk, Vitaly Zimyanin, Julia Japtok, Aaron Held, Arun Pal, Dajana Großmann, Hannes Glaß, Alexandra V Jürs, Banaja P Dash, Maciek Bak, Marcel Naumann, Christiane Hartmann, Olena Kuksenko, René Günther, Tzu-Ting Kao, Katrin Sameith, Andreas Dahl, Jared Sterneckert, Eleonora Aronica, Neil A Shneider, Andreas Büttner, Alberto Catanese, Hemali Phatnani, Markus Kipp, Brian J Wainger, Anand Goswami, Andreas Hermann.

  Mutations in the Fused in Sarcoma (FUS) gene cause familial amyotrophic lateral sclerosis (ALS), characterized by selective degeneration of spinal motor neurons (sMNs) with relative sparing of cortical neurons (CNs). The mechanisms underlying this cell-type vulnerability remain unclear. Here, we compare CNs and sMNs derived from FUS-ALS models to assess differential responses to FUS mutations. We find that CNs are less affected than sMNs in DNA damage repair, axonal organelle trafficking, and stress granule dynamics. RNA sequencing (RNA-seq) reveals distinct transcriptomic signatures, with sMNs uniquely activating DNA damage responses involving cell cycle regulators, particularly polo-like kinase 1 (PLK1). PLK1 is highly expressed in sMNs but not CNs, correlating with greater nuclear FUS loss and splicing defects in sMNs. Cross-comparison with other familial ALS RNA-seq datasets highlights PLK1 upregulation as a shared molecular feature. These findings identify intrinsic differences between CNs and sMNs in FUS-ALS and suggest PLK1 as a potential driver of sMN vulnerability.

Keywords:  CP: Molecular biology; CP: Neuroscience; DNA damage response; FUS loss of function; FUS-ALS; PLK1; neurodegeneration; polo-like kinase 1; selective vulnerability; transcriptomics

DOI:  https://doi.org/10.1016/j.celrep.2025.116113
Nat Commun. 2025 Aug 26. 16(1): 7951

ALS/FTD-linked TBK1 deficiency in microglia induces an aged-like microglial signature and drives social recognition deficits in mice.

Isadora Lenoel, Matthieu Ribon, Félicie Lorenc, Aurélien Diebold, Clementine E Philibert, David Robaldo, Manel Badsi, Julianne Perronnet, Julie Lameth, Felix Berriat, Hidemi Misawa, Marie Coutelier, Raphaelle Cassel, Nadège Sarrazin, Coline Jost-Mousseau, Delphine Bohl, Stéphanie Millecamps, Michel Mallat, David Brenner, Jochen H Weishaupt, Séverine Boillée, Christian S Lobsiger.

TANK-Binding Kinase 1 (TBK1) is involved in autophagy and immune signaling. Dominant loss-of-function mutations in TBK1 have been linked to Amyotrophic Lateral Sclerosis (ALS), Fronto-temporal dementia (FTD), and ALS/FTD. However, pathogenic mechanisms remain unclear, particularly the cell-type specific disease contributions of TBK1 mutations. Here, we show that deleting Tbk1 from mouse motor neurons does not induce transcriptional stress, despite lifelong signs of autophagy deregulations. Conversely, Tbk1 deletion in microglia alters their homeostasis and reactive responses. In both spinal cord and brain, Tbk1 deletion leads to a pro-inflammatory, primed microglial signature with features of ageing and neurodegeneration. While it does not induce or modify ALS-like motor neuron damage, microglial Tbk1 deletion is sufficient to cause early FTD-like social recognition deficits. This phenotype is linked to focal microglial activation and T cell infiltration in the substantia nigra pars reticulata and pallidum. Our results reveal that part of TBK1-linked FTD disease originates from microglial dysfunction.

DOI: https://doi.org/10.1038/s41467-025-63211-w
Mol Biol Rep. 2025 Aug 26. 52(1): 846

Rho kinase isoforms in neurodegeneration: from cellular functions to therapeutic targets.

Chesta Shandilya, Shalini Mani.

  Mitochondria serve as an important cellular organelle for maintaining neurotransmission and synaptic plasticity in neuronal cells by playing a key role in ATP generation, maintaining calcium homeostasis, and regulating the levels of reactive oxygen species (ROS), etc. The regulation of the dynamic nature of mitochondria, including their fission, fusion, and removal of damaged mitochondria by mitophagy, is also very important for neuronal health. Abnormalities in mitochondrial processes, including but not limited to fission, fusion, and mitophagy, are known to be associated with numerous neurodegenerative diseases (NDDs), such as Parkinson's disease (PD), Alzheimer's disease (AD), Amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). In the recent past, the Rho kinase (ROCK) isoforms, particularly ROCK1 and ROCK2, have gained a lot of attention in NDDs, mainly for their role in regulating the dynamics of the mitochondria, mitophagy, and other cell signalling pathways. By adding phosphate groups to Drp1, ROCK1 is crucial in supporting excessive mitochondrial fission, causing the death of neuronal cells. On the other hand, ROCK2 inhibits Parkin-dependent mitophagy by inhibiting the PTEN protein, the activator of Parkin-dependent mitophagy. This impaired mitochondrial quality control via reduced mitophagic flux leads to oxidative stress and neuronal degeneration, the central pathological feature of NDDs. The inhibition of ROCK isoforms has shown great promise in neuroprotective effects, controlling the dynamics of mitochondria in neuronal cells, lowering inflammation, and improving motor and cognitive functions in preclinical models of different NDDs, indicating ROCK isoforms as an attractive therapeutic target in different NDDs. This review aims to highlight the therapeutic significance of targeting ROCK isoforms in different NDDs.

Keywords:  Mitochondrial dynamics; Mitophagy; Neurodegenerative diseases; Neuroprotective; ROCK isoforms

DOI:  https://doi.org/10.1007/s11033-025-10947-9
Biochim Biophys Acta Mol Basis Dis. 2025 Aug 19. pii: S0925-4439(25)00369-2. [Epub ahead of print]1871(8): 168021

Mission cholesterol: Uncovering its hidden role in ALS neurodegeneration.

Anna Fernàndez-Bernal, Natàlia Mota, Reinald Pamplona, Estela Area-Gómez, Manuel Portero-Otin.

  Cholesterol is a central determinant of membrane architecture, signaling, and cellular homeostasis in the central nervous system (CNS). While historically viewed as a structural component, emerging evidence highlights its dynamic regulatory role in neuronal function, particularly through its compartmentalized synthesis, trafficking, and turnover. This review examines the complex landscape of cholesterol metabolism in the CNS, emphasizing the cooperative roles of astrocytes and neurons, the partitioning of biosynthetic pathways, and the barriers that distinguish brain cholesterol pools from peripheral sources. We focus on mitochondria-associated endoplasmic reticulum membranes (MAMs) as key regulatory platforms for cholesterol sensing, esterification, and signaling, underscoring their emerging role in neurodegenerative diseases. Disruptions in MAM integrity, lipid raft composition, and transcriptional regulation of cholesterol-handling genes have been linked to pathologies such as amyotrophic lateral sclerosis (ALS), particularly through the actions of TDP-43. By consolidating recent findings from lipidomics, cell biology, and disease models, we propose that cholesterol dyshomeostasis constitutes a shared mechanistic axis across diverse neurodegenerative conditions. Understanding this axis offers novel insights into the metabolic vulnerability of neurons and highlights cholesterol metabolism as a promising target for therapeutic intervention.

Keywords:  Amyotrophic Lateral Sclerosis; Astrocyte; Blood-brain-barrier; Endoplasmic reticulum; Neuron

DOI:  https://doi.org/10.1016/j.bbadis.2025.168021
Adv Sci (Weinh). 2025 Aug 23. e08902

Dimer-Specific FokT-seq Reveals DNA-Binding Dimerization and Novel Genomic Targets of TDP-43.

Mingming Yang, Qi Wang, Ruolan Yan, Xiaochuan Wang, Jianlan Gu.

  In postmortem brain tissues of patients with sporadic amyotrophic lateral sclerosis (ALS), the dimerization ability of TAR DNA-binding protein 43 (TDP-43) is impaired, accompanied by an accumulation of insoluble TDP-43. Thus, the loss of TDP-43 dimerization may play a critical driving role in ALS pathogenesis, although its underlying mechanism remains unclear. In this study, the FokT (FokI-TDP-43) system is developed, which fuses TDP-43 protein with FokI nuclease. By restoring TDP-43 dimerization, this system reactivates FokI nuclease activity, enabling the cleavage of DNA targets bound by TDP-43. Additionally, the FokT-seq (FokT combined with genome-wide unbiased identification of DNA double-strand breaks enabled by sequencing, Guide-seq) method is established, allowing genome-wide detection of DNA sites bound by dimerized TDP-43. These findings reveal the essential role of TDP-43 dimerization in DNA binding, identify a series of related targets. Furthermore, this study offers a powerful tool for investigating dimerized transcription factors.

Keywords:  DNA binding; FokT‐seq; TDP‐43; dimerization

DOI:  https://doi.org/10.1002/advs.202508902
Autophagy Rep. 2025 ;4(1): 2547194

During Aspergillus nidulans nitrogen-limited biofilm formation, mitophagy is independent of mitochondrial fission.

Hari Krishnan Balasubramanian, Stephen A Osmani.

  During chronic infections, biofilms are resistant to both antimicrobial agents as well as the host immune system, often giving rise to recalcitrant persister cells with reduced mitochondrial function rendering biofilm infections difficult to cure. How mitochondrial dynamics and fate are regulated during fungal biofilm formation is poorly understood. In this study, we used live cell microscopy to track mitochondrial morphology during Aspergillus nidulans in vitro biofilm formation. We show that mitochondria undergo fragmentation during early biofilm development, and that externally induced oxidative stress similarly induces mitochondrial fragmentation, indicating a role for redox regulation in this process. Deletion of core components of the mitochondrial fission machinery resulted in a swollen mitochondrial phenotype. Mitochondria in the fission-mutant strains are known not to complete fragmentation in response to externally induced oxidative stress, and we show that this results in a "beads on a string" phenotype. We further show that mitochondria remain unfragmented during biofilm formation in the fission-mutant strains, although other biofilm cellular modifications, like disassembly of microtubules, are unaffected. We report that mitophagy is triggered during biofilm development in nitrogen-limiting conditions independently of mitochondrial fission. This indicates mitochondrial fission is dispensable for mitophagy during biofilm development with limiting nitrogen. We further note that general autophagy, but notably not mitophagy, is triggered during biofilm development in carbon-limiting conditions, demonstrating differential regulation of mitochondrial fate in response to specific nutritional limitations during fungal biofilm formation.

Keywords:  Aspergillus nidulans; autophagy; biofilm formation; carbon; mitochondrial fission; mitophagy; nitrogen; redox regulation

DOI:  https://doi.org/10.1080/27694127.2025.2547194
Int J Mol Sci. 2025 Aug 15. pii: 7886. [Epub ahead of print]26(16):

Cathepsins in Neurological Diseases.

Dominik Lewandowski, Mateusz Konieczny, Agata Różycka, Krzysztof Chrzanowski, Wojciech Owecki, Jan Kalinowski, Mikołaj Stepura, Paweł Jagodziński, Jolanta Dorszewska.

  Cathepsins, a family of lysosomal proteases, play critical roles in maintaining cellular homeostasis through protein degradation and modulation of immune responses. In the central nervous system (CNS), their functions extend beyond classical proteolysis, influencing neuroinflammation, synaptic remodeling, and neurodegeneration. Emerging evidence underscores the crucial role of microglial cathepsins in the pathophysiology of several neurological disorders. This review synthesizes current knowledge on the involvement of cathepsins in a spectrum of CNS diseases, including Parkinson's disease, Alzheimer's disease, multiple sclerosis, amyotrophic lateral sclerosis, epilepsy, Huntington's disease, and ischemic stroke. We highlight how specific cathepsins contribute to disease progression by modulating key pathological processes such as α-synuclein and amyloid-β clearance, tau degradation, lysosomal dysfunction, neuroinflammation, and demyelination. Notably, several cathepsins demonstrate both neuroprotective and pathogenic roles depending on disease context and expression levels. Additionally, the balance between cathepsins and their endogenous inhibitors, such as cystatins, emerges as a critical factor in CNS pathology. While cathepsins represent promising biomarkers and therapeutic targets, significant gaps remain in our understanding of their mechanistic roles across diseases. Future studies focusing on their regulation, substrate specificity, and interplay with genetic and epigenetic factors may yield novel strategies for early diagnosis and disease-modifying treatments in neurology.

Keywords:  autophagy; cathepsins; neurodegenerative diseases; neuroinflammation; proteolysis

DOI:  https://doi.org/10.3390/ijms26167886
Nucleic Acids Res. 2025 Aug 11. pii: gkaf801. [Epub ahead of print]53(15):

DHX8 regulates degradation of RNA by RNautophagy.

Ryohei Sakai, Eigo Takeda, Chihana Kabuta, Viorica Raluca Contu, Yuuki Fujiwara, Nobuhiro Fujikake, Tadafumi Hashimoto, Yoshinori Ohsumi, Tomohiro Kabuta.

RNautophagy is an intracellular degradation pathway in which RNA is directly taken up by lysosomes. The cytoplasmic regions of the lysosomal membrane proteins, LAMP2C and SIDT2, can interact with consecutive guanine sequences in RNA, mediating the uptake of RNA during RNautophagy. RNautophagy has also been implicated in the clearance of expanded CAG-repeat mRNA and RNA foci associated with polyQ disease. However, the mechanisms of RNA uptake during RNautophagy remain unclear. Here, we screened for proteins that bind consecutive guanine sequences and identified RNA helicase DHX8 as a binding partner. DHX8 interacts with SIDT2 and is partially localized to the cytoplasmic side of the lysosomal membrane. We found that DHX8 regulates intracellular RNA degradation via SIDT2-dependent RNautophagy but not via macroautophagy. RNA binding, but not ATPase activity, of DHX8 is likely to be important for regulating RNA degradation. DHX8 also contributes to the clearance of pathogenic CAG repeat mRNA and RNA foci, and the levels of both soluble protein and insoluble high-molecular-weight aggregates of expanded polyQ tracts. Our findings provide insights into the mechanisms underlying the regulation of intracellular RNA degradation, autophagic pathways, and possibly the pathogenesis of repeat RNA-related disorders.

DOI: https://doi.org/10.1093/nar/gkaf801
Sci Rep. 2025 Aug 25. 15(1): 31244

Two specific interactions of GATE16 with TRPML3 and RAB33B regulate autophagy.

Jiwoo Park, Areum Choi, Jin Kwon, Suzi Choi, Yun Min Park, Hyun Jin Kim.

  ATG8s are essential for autophagy as they recruit various machinery to autophagic structures. We previously reported that the intracellular Ca2+ channel TRPML3 specifically interacts with the mammalian ATG8 homolog GATE16, but not LC3B to increase autophagy. However, the underlying mechanism and the role of this specific interaction remain unclear. Here, we report that single amino acid motifs in GATE16 and TRPML3 determine the specificity of this interaction and its function in autophagy. We also discovered that RAB33B, a Golgi-resident small GTPase, functionally interacts with TRPML3 in autophagy and contains an LC3-interacting region (LIR) motif. Surprisingly, RAB33B specifically interacted with GATE16, but not with other ATG8s through an LIR motif, and disrupting this LIR motif inhibited autophagy. Upon induction of autophagy, RAB33B was recruited from the Golgi to the phagophore in an LIR-dependent manner, enhancing the interaction between RAB33B and TRPML3 while promoting autophagy. These results suggest that specific interactions involving GATE16 play a crucial role in autophagy by recruiting TRPML3 and RAB33B, forming protein complexes at the phagophore to promote autophagosome formation.

Keywords:  ATG8; Autophagy; GATE16; RAB33B; TRPML3

DOI:  https://doi.org/10.1038/s41598-025-16951-0
FEBS J. 2025 Aug 23.

CDKL5 regulates the initiation of retrograde axonal transport through CLIP170-dynactin complex formation.

Serena Baldin, Clara Carmone, Giorgia Valetti, Roberta De Rosa, Isabella Barbiero.

  Cyclin-dependent kinase-like 5 (CDKL5) is a serine-threonine kinase implicated in regulating microtubule (MT) dynamics. Mutations in CDKL5 are associated with a rare neurodevelopmental disease called CDKL5 deficiency disorder (CDD), which is characterized by early-onset seizures and intellectual disabilities. Microtubule (MT)-related functions of CDKL5 are in part correlated with its interaction with MT-associated proteins, such as CAP-Gly domain-containing linker protein 1 [CLIP1; also known as cytoplasmic linker protein 170 alpha-2 (CLIP170)]. CLIP170 is a MT plus-end tracking protein that, once activated, can bind MTs and other proteins, favoring MT dynamics. Importantly, we have previously shown that CLIP170 is inactive in the absence of CDKL5, thus hindering MT functions. One of the best-characterized interactors of CLIP170 is dynactin, a multisubunit complex that binds the motor protein dynein. In particular, in neurons, active CLIP170 localizes to MTs in the axonal periphery, where it serves as a docking site for the interaction with dynactin, which in turn recruits dynein and various cargos, favoring the initiation of retrograde transport toward the neuronal soma. Here, we demonstrated that CLIP170-dynactin complex formation is impaired in the absence of CDKL5, thus leading to defective retrograde cargo trafficking. Overall, our findings expand the knowledge on the molecular mechanisms underlying neuronal transport and provide novel information regarding the etiopathogenesis of CDD.

Keywords:  CDKL5; microtubules; neurodevelopmental disorder; neurons; transport

DOI:  https://doi.org/10.1111/febs.70230
Cell. 2025 Aug 26. pii: S0092-8674(25)00908-0. [Epub ahead of print]

Molecular impact of antisense oligonucleotide therapy in C9orf72-associated ALS.

Zachary T McEachin, Mingee Chung, Sabrina A Stratton, Changhee Han, Woo Jae Kim, Udit Sheth, Eleanor V Thomas, Ethan Issenberg, Tanvi Kamra, Paola Merino, Yona Levites, Nisha Raj, Eric B Dammer, Duc M Duong, Lingyan Ping, Anantharaman Shantaraman, Adam N Trautwig, Joshna Gadhavi, Ezana Assefa, Marla Gearing, Kaylor M Kelly, Shanu F Roemer, Michael DeTure, Seneshaw Asress, Thomas Kukar, Christina Fournier, Dennis W Dickson, Leonard Petrucelli, Todd E Golde, Björn Oskarsson, Tania F Gendron, Nicholas T Seyfried, Jonathan D Glass.

  C9orf72-associated amyotrophic lateral sclerosis (c9ALS) is caused by an intronic G4C2 repeat expansion that leads to toxic RNA transcripts and dipeptide repeat proteins (DPRs). A clinical trial using the antisense oligonucleotide (ASO) BIIB078 to target these transcripts was discontinued after failing to provide clinical benefit. Here, we determine the extent of target engagement in the central nervous system (CNS) and elucidate pharmacodynamic cerebrospinal fluid (CSF) biomarkers following treatment. CSF from BIIB078-treated cases showed reduced DPRs and sustained increases in inflammatory biomarkers, including C-C motif chemokine ligand 26 (CCL26). BIIB078 was widely distributed in postmortem CNS tissue; however, DPRs and phosphorylated TDP-43 remained abundant. Proteomic signatures in c9ALS spinal cord were not altered with treatment, although a distinct increase in RNase T2 abundance that correlated with BIIB078 concentration was observed. Thus, despite widespread distribution, BIIB078 did not significantly impact key CNS pathologies, emphasizing the need to identify pharmacodynamic biomarkers that reflect disease-relevant neuropathological changes in response to ASO therapies.

Keywords:  BIIB078; C9orf72; NULISA; TDP-43; amyotrophic lateral sclerosis; antisense oligonucleotides; dipeptide repeat proteins; proteomics

DOI:  https://doi.org/10.1016/j.cell.2025.07.045
Cell Commun Signal. 2025 Aug 23. 23(1): 378

Elevated levels of Letm1 drives mitochondrial dysfunction and cardiomyocyte stress-mediated apoptosis in cultured cardiomyocytes.

Anushka Deshpande, Leo Weirauch, Tapan Kumar Baral, Marco Steier, Ankush Borlepawar, Manju Kumari, Lucia S Kilian, Karsten Richter, Elke Hammer, Derk Frank, Constanze Schmidt, Norbert Frey, Ashraf Y Rangrez.

   BACKGROUND: Cardiac ischemia, a predominant cause of heart failure, is marked by profound mitochondrial dysfunction, dysregulated ion homeostasis, and maladaptive cellular remodeling, all of which compromise cardiac performance. The mitochondrial inner membrane protein Leucine zipper-EF-hand containing Transmembrane Protein 1 (Letm1), implicated in Wolf-Hirschhorn Syndrome, is essential for mitochondrial function. Although genetic alterations in Letm1 are linked to cardiomyopathies, its specific contributions to cardiac pathophysiology, particularly in the context of ischemic heart disease, remain poorly defined. This study aims to elucidate the role of Letm1 in ischemic cardiac pathology and its mechanistic impact on cardiomyocyte function.
METHODS: Letm1 expression was assessed in human and murine models of heart failure due to ischemic cardiomyopathy (ICM) and cardiac hypertrophy. Letm1 was overexpressed in neonatal rat ventricular cardiomyocytes, adult mouse cardiomyocytes, and human induced pluripotent stem cell (iPSC)-derived cardiomyocytes to study mitochondrial function (Seahorse assays), structural and molecular remodeling (fluorescence microscopy, transmission electron microscopy (TEM), qPCR, immunoblotting), transcriptomic/proteomic profiles, calcium handling and electrophysiology (patch-clamp), autophagic flux (Bafilomycin A1, LC3-RFP-GFP), and cell survival.
RESULTS: Letm1 was markedly upregulated in ICM in both human and murine hearts, but unchanged in hypertrophic heart failure. Overexpression of Letm1 in cardiomyocytes resulted in profound mitochondrial dysfunction, including downregulation of oxidative phosphorylation (OXPHOS) genes, impaired membrane potential, reduced ATP output, increased proton leak, and elevated ROS levels. A metabolic shift toward glycolysis was observed, accompanied by reduced fatty acid oxidation. Electron microscopy revealed mitochondrial fragmentation, mitophagic vesicles, and sarcomeric disarray. Transcriptomic and proteomic analyses highlighted dysregulation of genes linked to mitochondrial organization, ion transport, and autophagy. Electrophysiologically, Letm1 reduced L-type Ca2+ current density and significantly shortened action potential duration, leading to impaired contractility. Letm1 overexpression activated upstream autophagy regulators (AMPK, ULK1) and enhanced LC3-II and p62 accumulation, but autophagic flux was impaired, as confirmed by LC3-RFP-GFP reporter and exacerbated by Bafilomycin A1 treatment. This dysregulated autophagy was coupled with mitochondrial stress, increased apoptosis (cleaved caspases), and reduced cardiomyocyte viability.
CONCLUSION: This study indicates that Letm1 upregulation drives mitochondrial dysfunction, electrophysiology alterations, and activation of autophagy and apoptosis, culminating in cardiomyocyte injury in ischemic cardiomyopathy. By disrupting OXPHOS, calcium handling, and cell survival pathways, Letm1 contributes to ischemic remodeling and cardiac dysfunction. Targeting Letm1 presents a promising therapeutic strategy to alleviate ischemic damage and preserve cardiac function.

Keywords:  Arrhythmias; Cardiomyocytes; Hypertrophy; Letm1; Mitochondrial metabolism

DOI:  https://doi.org/10.1186/s12964-025-02378-7
J Physiol. 2025 Aug 22.

Neurobiology of mitochondrial dynamics in sleep.

Raffaele Sarnataro.

  The cycling of sleep and wakefulness reshapes neuronal activity, gene expression, and cellular metabolism of the brain. Such reshuffling of brain metabolism implicates key mediation by mitochondria. Mitochondrial dynamics enable organelles to adapt their morphofunction to changing metabolic demands, and experimental evidence increasingly links these processes to sleep-wake regulation. Across species, sleep loss perturbs mitochondrial gene expression, increases oxidative stress, and disrupts organelle structure, particularly in energy-demanding brain regions. In Drosophila, sleep-control neurons projecting to the dorsal fan-shaped body (dFBNs) exhibit a homeostatic feedback mechanism coupling mitochondrial activity to behavioural state. As sleep pressure elevates, dopaminergic inhibition reduces dFBN excitability and ATP consumption, triggering mitochondrial fission and accumulation of reactive oxygen species (ROS) that biochemically prime the neurons for subsequent sleep induction. Upon relief of inhibition during recovery sleep, dFBNs elevate their activity, consume ATP, and undergo mitochondrial fusion to restore energy balance. Artificial modulation of mitochondrial morphology and ATP production in these neurons bidirectionally alters sleep. dFBNs' elevated OxPhos expression and mitochondrial turnover render them sensitive to metabolic shifts and capable of encoding internal states. While dFBNs remain the only known neurons where mitochondrial dynamics are coupled to sleep behaviour, other populations, like mammalian cortical neurons or fly Kenyon cells, also display mitochondrial changes after sleep loss. Sleep, like other state-dependent behaviours including hunger and memory, imposes shifting energetic demands on specific neuronal populations. Mitochondrial dynamics may thus provide a conserved, cell-autonomous mechanism for tuning neural excitability and sleep pressure, enabling brain-wide coordination of metabolic and behavioural homeostasis.

Keywords:  ATP; energy; homeostasis; metabolism; mitochondria; neurobiology; neuron; sleep

DOI:  https://doi.org/10.1113/JP288054