bims-axbals 2025-04-13 papers

bims-axbals

Biomed News

on Axonal biology and ALS

Issue of 2025–04–13
twenty-six papers selected by
TJ Krzystek

Pathogenic TDP-43 in amyotrophic lateral sclerosis.
Differential neuronal vulnerability to C9orf72 repeat expansion driven by Xbp1-induced endoplasmic reticulum-associated degradation.
Targeting senescence in Amyotrophic Lateral Sclerosis: senolytic treatment improves neuromuscular function and preserves cortical excitability in a TDP-43Q331K mouse model.
High-throughput screen of 100 000 small molecules in C9ORF72 ALS neurons identifies spliceosome modulators that mobilize G4C2 repeat RNA into nuclear export and repeat associated non-canonical translation.
The bridge-like lipid transport protein VPS13C/PARK23 mediates ER-lysosome contacts following lysosome damage.
Mutant huntingtin induces neuronal apoptosis via derepressing the non-canonical poly(A) polymerase PAPD5.
The Role of Autophagy in Excitotoxicity, Synaptic Mitochondrial Stress and Neurodegeneration.
Mitochondrial and energy metabolism dysfunctions are hallmarks of TDP-43G376D fibroblasts from members of an Amyotrophic Lateral Sclerosis family.
Glia get RIPped in ALS.
Rate of change in upper and lower motor neuron burden is associated with survival in amyotrophic lateral sclerosis.
Activating autophagy to eliminate toxic protein aggregates with small molecules in neurodegenerative diseases.
Improving mitochondria-associated endoplasmic reticulum membranes integrity as converging therapeutic strategy for rare neurodegenerative diseases and cancer.
Mutated sigma-1R disrupts cell homeostasis in dHMN patient cells.
R-loops in neurodegeneration.
An in vitro platform for characterizing axonal electrophysiology of individual human iPSC-derived nociceptors.
Autophagy: a double-edged sword in ischemia-reperfusion injury.
Interactions among Merlin, Arkadia, and SKOR2 mediate NF2-associated human Schwann cell proliferation.
Genome editing in spinocerebellar ataxia type 3 cells improves Golgi apparatus structure.
α-Synuclein interacts directly with AP2 and regulates its binding to synaptic membranes.
In vitro model of ischemic stroke neurons from Macaca fascicularis.
Rab GTPases as "eat me" signals for selective autophagy.
Quiescent cell re-entry is limited by macroautophagy-induced lysosomal damage.
The autophagy protein ATG-9 regulates lysosome function and integrity.
Poster Session: Abnormal GSK3β activity affects Drosophila vision.
STING mediates lysosomal quality control and recovery through its proton channel function and TFEB activation in lysosomal storage disorders.
Neurofilament light chain induces neuroinflammation.

Drug Discov Today. 2025 Apr 04. pii: S1359-6446(25)00064-9. [Epub ahead of print] 104351

Pathogenic TDP-43 in amyotrophic lateral sclerosis.

Zhao Zhong Chong, Nizar Souayah.

  The aberrant expression of the trans-active response DNA-binding protein of 43 kDa (TDP-43) has been closely associated with amyotrophic lateral sclerosis (ALS). Cytoplasmic inclusions containing TDP-43 can be found in the brain and spinal cord in up to 97% of ALS cases. Mutations in the TARDBP gene promote the nuclear export of TDP-43, increase cytoplasmic aggregation, and predispose TDP-43 to post-translational modifications. Cleavage of TDP-43 and the resulting C- and N-terminal fragments also contribute to the development of ALS. Cellularly, the resulting impairment of autophagy and mitochondria aggravates cellular damage and neurodegeneration. Given the contribution of pathogenic TDP-43 to the development of ALS, elucidating the mechanisms related to TDP-43 will facilitate finding therapeutic targets for the disease.

Keywords:  TARDBP gene; TDP-43; amyotrophic lateral sclerosis; autophagy; neurodegeneration

DOI:  https://doi.org/10.1016/j.drudis.2025.104351
Cell Rep. 2025 Mar 23. pii: S2211-1247(25)00230-X. [Epub ahead of print] 115459

Differential neuronal vulnerability to C9orf72 repeat expansion driven by Xbp1-induced endoplasmic reticulum-associated degradation.

Dunxin Shen, Alec Vincent, Evan Udine, Yazead Buhidma, Sharifah Anoar, Elli Tsintzas, Marie Maeland, Dongwei Xu, Mireia Carcolé, David Osumi-Sutherland, Benjamin Aleyakpo, Alexander Hull, Guillermo Martínez Corrales, Nathan Woodling, Rosa Rademakers, Adrian M Isaacs, Carlo Frigerio, Marka van Blitterswijk, Tammaryn Lashley, Teresa Niccoli.

  Neurodegenerative diseases are characterized by the localized loss of neurons. Why cell death is triggered only in specific neuronal populations and whether it is the response to toxic insults or the initial cellular state that determines their vulnerability is unknown. To understand individual cell responses to disease, we profiled their transcriptional signatures throughout disease development in a Drosophila model of C9orf72 (G4C2) repeat expansion (C9), the most common genetic cause of frontotemporal dementia and amyotrophic lateral sclerosis. We identified neuronal populations specifically vulnerable or resistant to C9 expression and found an upregulation of protein homeostasis pathways in resistant neurons at baseline. Overexpression of Xbp1s, a key regulator of the unfolded protein response and a central node in the resistance network, rescues C9 toxicity. This study shows that neuronal vulnerability depends on the intrinsic transcriptional state of neurons and that leveraging resistant neurons' properties can boost resistance in vulnerable neurons.

Keywords:  ALS; C9; C9orf72; CP: Molecular biology; CP: Neuroscience; Drosophila; ERAD; FTD; Xbp1; neuronal vulnerability; protein homeostasis; unfolded protein response

DOI:  https://doi.org/10.1016/j.celrep.2025.115459
Res Sq. 2025 Mar 26. pii: rs.3.rs-6081213. [Epub ahead of print]

Targeting senescence in Amyotrophic Lateral Sclerosis: senolytic treatment improves neuromuscular function and preserves cortical excitability in a TDP-43Q331K mouse model.

Jose A Viteri, Nathan R Kerr, Charles D Brennan, Grace R Kick, Meifang Wang, Arsh Ketabforoush, Harper K Snyder, Peter J Moore, Fereshteh B Darvishi, Anna Roshani Dashtmian, Sindhuja N Ayyagari, Kelly Rich, Yi Zhu, W David Arnold.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder marked by progressive motor neuron degeneration in the primary motor cortex (PMC) and spinal cord. Aging is a key factor in ALS onset and progression, with evidence suggesting that biological aging-a process involving cellular decline- far outpaces chronological aging in ALS. This promotes senescent cell accumulation-marked by irreversible cell-cycle arrest, impaired apoptosis, and chronic inflammation-disrupting tissue homeostasis and impairing neuronal support functions. Thus, targeting senescence presents a novel therapeutic strategy for ALS. Here, we investigated the senolytic combination Dasatinib and Quercetin (D&Q) in TDP-43 Q331K ALS mice. D&Q improved neuromuscular function and reduced plasma neurofilament light chain, a biomarker of axonal damage. The most pronounced improvement was the improved cortical excitability, accompanied by reductions in senescence and TDP-43 in the PMC. These findings highlight the potential of senolytics to mitigate ALS-related dysfunction, supporting their viability as a therapeutic strategy. *Jose A. Viteriab, Nathan R. Kerrab, and Charles D. Brennana are co-first authors.

DOI: https://doi.org/10.21203/rs.3.rs-6081213/v1
Nucleic Acids Res. 2025 Apr 10. pii: gkaf253. [Epub ahead of print]53(7):

High-throughput screen of 100 000 small molecules in C9ORF72 ALS neurons identifies spliceosome modulators that mobilize G4C2 repeat RNA into nuclear export and repeat associated non-canonical translation.

Maartje J Luteijn, Varun Bhaskar, Dominic Trojer, Melanie Schürz, Hicham Mahboubi, Cornelia Handl, Nicolas Pizzato, Martin Pfeifer, Ruxandra Dafinca, Hans Voshol, Elisa Giorgetti, Carole Manneville, Isabelle P M Garnier, Matthias Müller, Fanning Zeng, Kathrin Buntin, Roger Markwalder, Harald Schröder, Jan Weiler, Dora Khar, Tim Schuhmann, Paul J Groot-Kormelink, Caroline Gubser Keller, Pierre Farmer, Angela MacKay, Martin Beibel, Guglielmo Roma, Giovanni D'Ario, Claudia Merkl, Michael Schebesta, Marc Hild, Fiona Elwood, Björn F Vahsen, Nina Ripin, Antoine Clery, Frederic Allain, Mark Labow, Daniela Gabriel, Jeffrey A Chao, Kevin Talbot, Mark Nash, Jürg Hunziker, Nicole C Meisner-Kober.

An intronic G4C2 repeat expansion in the C9ORF72 gene is the major known cause for Amyotrophic Lateral Sclerosis (ALS), with current evidence for both, loss of function and pathological gain of function disease mechanisms. We screened 96 200 small molecules in C9ORF72 patient iPS neurons for modulation of nuclear G4C2 RNA foci and identified 82 validated hits, including the Brd4 inhibitor JQ1 as well as novel analogs of Spliceostatin-A, a known modulator of SF3B1, the branch point binding protein of the U2-snRNP. Spliceosome modulation by these SF3B1 targeted compounds recruits SRSF1 to nuclear G4C2 RNA, mobilizing it from RNA foci into nucleocytoplasmic export. This leads to increased repeat-associated non-canonical (RAN) translation and ultimately, enhanced cell toxicity. Our data (i) provide a new pharmacological entry point with novel as well as known, publicly available tool compounds for dissection of C9ORF72 pathobiology in C9ORF72 ALS models, (ii) allowing to differentially modulate RNA foci versus RAN translation, and (iii) suggest that therapeutic RNA foci elimination strategies warrant caution due to a potential storage function, counteracting translation into toxic dipeptide repeat polyproteins. Instead, our data support modulation of nuclear export via SRSF1 or SR protein kinases as possible targets for future pharmacological drug discovery.

DOI: https://doi.org/10.1093/nar/gkaf253
Nat Cell Biol. 2025 Apr 10.

The bridge-like lipid transport protein VPS13C/PARK23 mediates ER-lysosome contacts following lysosome damage.

Xinbo Wang, Peng Xu, Amanda Bentley-DeSousa, William Hancock-Cerutti, Shujun Cai, Benjamin T Johnson, Francesca Tonelli, Lin Shao, Gabriel Talaia, Dario R Alessi, Shawn M Ferguson, Pietro De Camilli.

Based on genetic studies, lysosome dysfunction is thought to play a pathogenetic role in Parkinson's disease. Here we show that VPS13C, a bridge-like lipid-transport protein and a Parkinson's disease gene, is a sensor of lysosome stress or damage. Following lysosome membrane perturbation, VPS13C rapidly relocates from the cytosol to the surface of lysosomes where it tethers their membranes to the ER. This recruitment depends on Rab7 and requires a signal at the damaged lysosome surface that releases an inhibited state of VPS13C, which hinders access of its VAB domain to lysosome-bound Rab7. Although another Parkinson's disease protein, LRRK2, is also recruited to stressed or damaged lysosomes, its recruitment occurs at much later stages and by different mechanisms. Given the role of VPS13 proteins in bulk lipid transport, these findings suggest that lipid delivery to lysosomes by VPS13C is part of an early protective response to lysosome damage.

DOI: https://doi.org/10.1038/s41556-025-01653-6
Nat Commun. 2025 Apr 09. 16(1): 3307

Mutant huntingtin induces neuronal apoptosis via derepressing the non-canonical poly(A) polymerase PAPD5.

Zhefan Stephen Chen, Shaohong Isaac Peng, Lok I Leong, Terence Gall-Duncan, Nathan Siu Jun Wong, Tsz Ho Li, Xiao Lin, Yuming Wei, Alex Chun Koon, Junzhe Huang, Jacquelyne Ka-Li Sun, Clinton Turner, Lynette Tippett, Maurice A Curtis, Richard L M Faull, Kin Ming Kwan, Hei-Man Chow, Ho Ko, Ting-Fung Chan, Kevin Talbot, Christopher E Pearson, Ho Yin Edwin Chan.

MicroRNAs (miRNAs) are small non-coding RNAs that play crucial roles in post-transcriptional gene regulation. Poly(A) RNA polymerase D5 (PAPD5) catalyzes the addition of adenosine to the 3' end of miRNAs. In this study, we demonstrate that the Yin Yang 1 protein, a transcriptional repressor of PAPD5, is recruited to both RNA foci and protein aggregates, resulting in an upregulation of PAPD5 expression in Huntington's disease (HD). Additionally, we identify a subset of PAPD5-regulated miRNAs with increased adenylation and reduced expression in our disease model. We focus on miR-7-5p and find that its reduction causes the activation of the TAB2-mediated TAK1-MKK4-JNK pro-apoptotic pathway. This pathway is also activated in induced pluripotent stem cell-derived striatal neurons and post-mortem striatal tissues isolated from HD patients. In addition, we discover that a small molecule PAPD5 inhibitor, BCH001, can mitigate cell death and neurodegeneration in our disease models. This study highlights the importance of PAPD5-mediated miRNA dysfunction in HD pathogenesis and suggests a potential therapeutic direction for the disease.

DOI: https://doi.org/10.1038/s41467-025-58618-4
Autophagy Rep. 2025 ;pii: 2464376. [Epub ahead of print]4(1):

The Role of Autophagy in Excitotoxicity, Synaptic Mitochondrial Stress and Neurodegeneration.

Charleen T Chu.

  Brain and nervous system functions depend upon maintaining the integrity of synaptic structures over the lifetime. Autophagy, a key homeostatic quality control system, plays a central role not only in neuronal development and survival/cell death, but also in regulating synaptic activity and plasticity. Glutamate is the major excitatory neurotransmitter that activates downstream targets, with a key role in learning and memory. However, an excess of glutamatergic stimulation is pathological in stroke, epilepsy and neurodegeneration, triggering excitotoxic cell death or a sublethal process of excitatory mitochondrial calcium toxicity (EMT) that triggers dendritic retraction. Markers of autophagy and mitophagy are often elevated following excitatory neuronal injuries, with the potential to influence cell death or neurodegenerative outcomes of these injuries. Interestingly, leucine-rich repeat kinase 2 (LRRK2) and PTEN-induced kinase 1 (PINK1), two kinases linked to autophagy, mitophagy and Parkinson disease, play important roles in regulating mitochondrial calcium handling, synaptic density and function, and maturation of dendritic spines. Mutations in LRRK2, PINK1, or proteins linked to Alzheimer's disease perturb mitochondrial calcium handling to sensitize neurons to excitatory injury. While autophagy and mitophagy can play both protective and harmful roles, studies in various excitotoxicity and stroke models often implicate autophagy in a pathogenic role. Understanding the role of autophagic degradation in regulating synaptic loss and cell death following excitatory neuronal injuries has important therapeutic implications for both acute and chronic neurological disorders.

Keywords:  Alzheimer disease; Epilepsy; Glutamate toxicity; Leucine-rich repeat kinase 2; Mitochondrial Na+/Ca2+ exchanger; Mitochondrial calcium uniporter; PTEN-induced kinase 1; Parkinson disease; hypoxia-ischemia; post-synaptic calcium

DOI:  https://doi.org/10.1080/27694127.2025.2464376
Cell Death Dis. 2025 Apr 10. 16(1): 272

Mitochondrial and energy metabolism dysfunctions are hallmarks of TDP-43G376D fibroblasts from members of an Amyotrophic Lateral Sclerosis family.

Elisa Perciballi, Federica Bovio, Sara Ferro, Matilde Forcella, Jessica Rosati, Rose Mary Carletti, Angela D'Anzi, Maurizio Gelati, Vincenzo La Bella, Metello Innocenti, Rossella Spataro, Martina Pecoraro, Ivan Lombardi, Edvige Vulcano, Giorgia Ruotolo, Sara Mercurio, Mario Sabatelli, Serena Lattante, Tarja Malm, Sohvi Ohtonen, Angelo Luigi Vescovi, Paola Fusi, Daniela Ferrari.

Amyotrophic Lateral Sclerosis (ALS) is an incurable neurodegenerative disease, causing degeneration of motor neurons, paralysis, and death. About 5-10% of cases are associated with gene mutations inherited from a family member (fALS). Among them, mutations in the transactive-response (TAR)-DNA-binding protein (TARDBP), which encodes for the TAR DNA binding protein 43 (TDP-43) are responsible for 4-5% of fALS but the molecular mechanisms that initiate and sustain the neurodegenerative process are largely unknown. Metabolic impairments might be involved in the pathogenesis of ALS and are currently under investigation. In order to correlate biochemical and metabolic alterations with disease progression, here, we established the metabolic fingerprint of dermal fibroblasts derived from symptomatic and asymptomatic members of a family with fALS cases carrying to the p.G376D mutation in TDP-43. We found that increased proliferation, unbalanced oxidative homeostasis and higher ATP production rate coupled with enhanced metabolic activity are underlying traits of this family. Fibroblasts from carrier individuals deploy several mechanisms to increase mitochondrial respiration to meet increasing energy demands. This is accompanied by an upregulation of glycolysis corresponding to a metabolic reprograming towards a glycolytic phenotype for ATP production during ALS progression, particularly in late disease stages. In summary, we uncover alterations in energy metabolism in TDP43G376D patient-derived primary fibroblasts that may be used as risk biomarkers and/or to monitor ALS progression.

DOI: https://doi.org/10.1038/s41419-025-07584-2
Immunity. 2025 Apr 08. pii: S1074-7613(25)00132-3. [Epub ahead of print]58(4): 778-780

Glia get RIPped in ALS.

Alexis M Johnson, John R Lukens.

While neuroinflammatory responses driven by microglia and astrocytes have been extensively linked to neurodegenerative disease progression in amyotrophic lateral sclerosis (ALS), the specific pathways that coordinate glial cell-dependent neuroinflammation in ALS remain poorly defined. In this issue of Immunity, Zelic et al.1 identified RIPK1 as a pivotal regulator of glial cell-driven neuroinflammation in multiple ALS models.

DOI: https://doi.org/10.1016/j.immuni.2025.03.013
J Neurol. 2025 Apr 04. 272(4): 315

Rate of change in upper and lower motor neuron burden is associated with survival in amyotrophic lateral sclerosis.

A Maranzano, F Gentile, M Passaretti, A Doretti, E Colombo, A K Wall, M Treddenti, V Patisso, A De Lorenzo, C Gendarini, A Cocuzza, A D Maio, S Pierro, B Poletti, C M Cinnante, C Morelli, S Messina, J B Pereira, O Hardiman, V Silani, F Verde, N Ticozzi.

   BACKGROUND: We hypothesize that the rate of change in upper (ΔUMN) and lower (ΔLMN) motor neuron signs from symptom onset to first clinical assessment represent best predictors of survival and disease progression in amyotrophic lateral sclerosis (ALS) compared to singular quantification of UMN and LMN involvement.
METHODS: A retrospective inpatient cohort of 1000 ALS patients was evaluated. The burden of UMN and LMN signs was assessed using the Penn Upper Motor Neuron Score and Lower Motor Neuron Score, respectively. For 421 patients, we compute the ENCALS survival model. Univariate and regularized Cox regressions were conducted to estimate the effect of the aforementioned variables on survival. The ROC curve analysis was then employed to a training sub-cohort to identify a ΔLMN cut-off value discriminating ALS patients with prolonged vs short survival. This cut-off value was then cross validated on a test sub-cohort. A multinomial regression model was used to compare different ΔUMN and ΔLMN scores among ENCALS groups.
RESULTS: ΔUMN and ΔLMN showed a negative association with survival (ΔUMN: HR = 1.30; ΔLMN: HR = 4.22). A cut-off value of 0.22 for ΔLMN was identified to predict patients with estimated short vs prolonged survival. ENCALS groups characterized by shorter survival presented significantly higher ΔUMN and ΔLMN scores compared to those with longer survival. No significant association of PUMNS or LMNS gross scores with the above-mentioned variables was observed.
CONCLUSION: By reflecting the progressing degeneration of the two distinct motor neuron subpopulations, ΔUMN and ΔLMN might represent reliable and easily measurable clinical indexes to estimate survival in ALS.

Keywords:  Amyotrophic lateral sclerosis; Motor indexes; Prognosis; Survival

DOI:  https://doi.org/10.1007/s00415-025-13052-w
Pharmacol Rev. 2025 Mar 14. pii: S0031-6997(25)07461-7. [Epub ahead of print]77(3): 100053

Activating autophagy to eliminate toxic protein aggregates with small molecules in neurodegenerative diseases.

Yuqi Fu, Jin Zhang, Rui Qin, Yueting Ren, Tingting Zhou, Bo Han, Bo Liu.

Neurodegenerative diseases (NDs), such as Alzheimer disease, Parkinson disease, Huntington disease, amyotrophic lateral sclerosis, and frontotemporal dementia, are well known to pose formidable challenges for their treatment due to their intricate pathogenesis and substantial variability among patients, including differences in environmental exposures and genetic predispositions. One of the defining characteristics of NDs is widely reported to be the buildup of misfolded proteins. For example, Alzheimer disease is marked by amyloid beta and hyperphosphorylated Tau aggregates, whereas Parkinson disease exhibits α-synuclein aggregates. Amyotrophic lateral sclerosis and frontotemporal dementia exhibit TAR DNA-binding protein 43, superoxide dismutase 1, and fused-in sarcoma protein aggregates, and Huntington disease involves mutant huntingtin and polyglutamine aggregates. These misfolded proteins are the key biomarkers of NDs and also serve as potential therapeutic targets, as they can be addressed through autophagy, a process that removes excess cellular inclusions to maintain homeostasis. Various forms of autophagy, including macroautophagy, chaperone-mediated autophagy, and microautophagy, hold a promise in eliminating toxic proteins implicated in NDs. In this review, we focus on elucidating the regulatory connections between autophagy and toxic proteins in NDs, summarizing the cause of the aggregates, exploring their impact on autophagy mechanisms, and discussing how autophagy can regulate toxic protein aggregation. Moreover, we underscore the activation of autophagy as a potential therapeutic strategy across different NDs and small molecules capable of activating autophagy pathways, such as rapamycin targeting the mTOR pathway to clear α-synuclein and Sertraline targeting the AMPK/mTOR/RPS6KB1 pathway to clear Tau, to further illustrate their potential in NDs' therapeutic intervention. Together, these findings would provide new insights into current research trends and propose small-molecule drugs targeting autophagy as promising potential strategies for the future ND therapies. SIGNIFICANCE STATEMENT: This review provides an in-depth overview of the potential of activating autophagy to eliminate toxic protein aggregates in the treatment of neurodegenerative diseases. It also elucidates the fascinating interrelationships between toxic proteins and the process of autophagy of "chasing and escaping" phenomenon. Moreover, the review further discusses the progress utilizing small molecules to activate autophagy to improve the efficacy of therapies for neurodegenerative diseases by removing toxic protein aggregates.

DOI: https://doi.org/10.1016/j.pharmr.2025.100053
Biochim Biophys Acta Mol Cell Res. 2025 Apr 09. pii: S0167-4889(25)00059-X. [Epub ahead of print] 119954

Improving mitochondria-associated endoplasmic reticulum membranes integrity as converging therapeutic strategy for rare neurodegenerative diseases and cancer.

Michal Cagalinec, Mohd Adnan, Silvia Borecka, Geert Bultynck, Vinay Choubey, Shira Yanovsky-Dagan, Shlomit Ezer, Daniela Gasperikova, Tamar Harel, Dana Jurkovicova, Allen Kaasik, Jean-Charles Liévens, Tangui Maurice, Marco Peviani, Elodie Marie Richard, Jan Skoda, Martina Skopkova, Pauline Tarot, Robbe Van Gorp, Liga Zvejniece, Benjamin Delprat.

  Membrane contact sites harbor a distinct set of proteins with varying biological functions, thereby emerging as hubs for localized signaling nanodomains underlying adequate cell function. Here, we will focus on mitochondria-associated endoplasmic reticulum membranes (MAMs), which serve as hotspots for Ca2+ signaling, redox regulation, lipid exchange, mitochondrial quality and unfolded protein response pathway. A network of MAM-resident proteins contributes to the structural integrity and adequate function of MAMs. Beyond endoplasmic reticulum (ER)-mitochondrial tethering proteins, MAMs contain several multi-protein complexes that mediate the transfer of or are influenced by Ca2+, reactive oxygen species and lipids. Particularly, IP3 receptors, intracellular Ca2+-release channels, and Sigma-1 receptors (S1Rs), ligand-operated chaperones, serve as important platforms that recruit different accessory proteins and intersect with these local signaling processes. Furthermore, many of these proteins are directly implicated in pathophysiological conditions, where their dysregulation or mutation is not only causing diseases such as cancer and neurodegeneration, but also rare genetic diseases, for example familial Parkinson's disease (PINK1, Parkin, DJ-1), familial Amyotrophic lateral sclerosis (TDP43), Wolfram syndrome1/2 (WFS1 and CISD2), Harel-Yoon syndrome (ATAD3A). In this review, we will discuss the current state-of-the-art regarding the molecular components, protein platforms and signaling networks underlying MAM integrity and function in cell function and how their dysregulation impacts MAMs, thereby driving pathogenesis and/or impacting disease burden. We will highlight how these insights can generate novel, potentially therapeutically relevant, strategies to tackle disease outcomes by improving the integrity of MAMs and the signaling processes occurring at these membrane contact sites.

Keywords:  ATAD3A related disorders; Amyotrophic lateral sclerosis; Calcium signaling; Endoplasmic reticulum stress; Familial Parkinson's disease; Harel-Yoon syndrome; Metabolomics; Mitochondria quality control; Mitochondria-associated endoplasmic reticulum membranes; Rare neurodegenerative diseases; Wolfram syndrome; cancer

DOI:  https://doi.org/10.1016/j.bbamcr.2025.119954
Cell Mol Life Sci. 2025 Apr 09. 82(1): 151

Mutated sigma-1R disrupts cell homeostasis in dHMN patient cells.

Sofia Zanin, Francesco Ciscato, Antonio Petrucci, Annalisa Botta, Federico Chiossi, Giovanni Vazza, Rosario Rizzuto, Giorgia Pallafacchina.

  Hereditary-Motor-Neuropathies (dHMNs) are clinically and genetically heterogeneous neurological disorders characterized by degeneration of peripheral motoneurons. We previously identified two sigma-1 receptor (Sigma-1R) variants (p.E138Q; p.E150K) in dHMN Italian patients that behave as "loss-of-function" mutations in neuroblastoma cell lines. Here, we characterize the functional effects of Sigma-1R mutation in primary fibroblasts from homozygous patients bearing the E150K mutation, and matched controls, by performing biochemical, gene expression, immunofluorescence and Ca2+ imaging analysis. Our results show that Sigma-1R expression and distribution is significantly altered in patient fibroblasts. Moreover, patient cells present a general derangement of cell homeostasis as revealed by impairment of global Ca2+ dynamics, disorganization of the ER-mitochondria tethers, enhancement of the autophago-lysosomal pathway and blunting of mitochondrial aerobic metabolism compared to controls. These findings highlight the crucial role of Sigma-1R in the maintenance of cell and protein homeostasis, inter-organelle communication and intracellular Ca2+ signalling, supporting the notion that Sigma-1R is protective for motor neuron activity and its down-regulation and/or loss-of-function, as in the case of the E150K mutation, might play the key role in the neuronal degeneration in dHMN patients.

Keywords:  Ca2+ signalling; Cellular proteostasis; ER-mitochondria contacts; Hereditary neuropathies; Sigma-1R

DOI:  https://doi.org/10.1007/s00018-025-05676-y
Curr Opin Genet Dev. 2025 Apr 08. pii: S0959-437X(25)00037-1. [Epub ahead of print]92 102345

R-loops in neurodegeneration.

Chiara Beghѐ, Helena Harpham, Yasmine Barberic, Natalia Gromak.

Neurodegenerative diseases are associated with the progressive loss of neurons. R-loops are non-canonical nucleic acid structures formed during transcription and composed of an RNA/DNA hybrid and a displaced single-stranded DNA. Whilst R-loops are important regulators of cellular processes, they are also associated with the pathologies of multiple disorders, including repeat expansion, motor neuron, inflammatory and ageing diseases. In this review, we discuss how R-loops contribute to pathological mechanisms that underpin neurodegeneration. We highlight the role of R-loops in several hallmarks of neurodegenerative disorders, including RNA and DNA defects, DNA damage, protein aggregation, inflammation, mitochondrial dysfunction, and neuronal cell death. We also discuss the potential role of R-loops as therapeutic targets for neurodegenerative disorders.

DOI: https://doi.org/10.1016/j.gde.2025.102345
Biosens Bioelectron. 2025 Apr 02. pii: S0956-5663(25)00292-1. [Epub ahead of print]281 117418

An in vitro platform for characterizing axonal electrophysiology of individual human iPSC-derived nociceptors.

Blandine F Clément, Lorenzo Petrella, Lea Wallimann, Jens Duru, Christina M Tringides, János Vörös, Tobias Ruff.

  Neuropathic pain is characterized by aberrant activity of specific nociceptor populations, as demonstrated through functional assessments such as microneurography. Current treatments against severe forms of neuropathic pain demonstrate insufficient efficacy or lead to unwanted side effects as they fail to specifically target the affected nociceptors. Tools that can recapitulate aspects of microneurography in vitro would enable a more targeted compound screening. Therefore, we developed an in vitro platform combining a CMOS-based high-density microelectrode array with a polydimethylsiloxane (PDMS) guiding microstructure that captures the electrophysiological responses of individual axons. Human induced pluripotent stem cell-derived (hiPSC) sensory neurons were cultured in a way that allowed axons to be distributed through parallel 4 ×10μm microchannels exiting the seeding well before converging to a bigger axon-collecting channel. This configuration allowed the measurement of stimulation-induced responses of individual axons. Sensory neurons were found to exhibit a great diversity of electrophysiological response profiles that can be classified into different functional archetypes. Moreover, we show that some responses are affected by applying the TRPV1 agonist capsaicin. Overall, results using our platform demonstrate that we were able to distinguish individual axon responses, making the platform a promising tool for testing therapeutic candidates targeting particular sensory neuron subtypes.

Keywords:  Activity-dependent slowing; Axonal conduction; CMOS-based microelectrode array; Human iPSC-derived sensory neurons; In vitro model; Nociception; PDMS microstructures

DOI:  https://doi.org/10.1016/j.bios.2025.117418
Cell Mol Biol Lett. 2025 Apr 07. 30(1): 42

Autophagy: a double-edged sword in ischemia-reperfusion injury.

Lingxuan Tang, Wangzheqi Zhang, Yan Liao, Weijie Wang, Xiaoming Deng, Changli Wang, Wenwen Shi.

  Ischemia-reperfusion (I/R) injury describes the pathological process wherein tissue damage, initially caused by insufficient blood supply (ischemia), is exacerbated upon the restoration of blood flow (reperfusion). This phenomenon can lead to irreversible tissue damage and is commonly observed in contexts such as cardiac surgery and stroke, where blood supply is temporarily obstructed. During ischemic conditions, the anaerobic metabolism of tissues and organs results in compromised enzyme activity. Subsequent reperfusion exacerbates mitochondrial dysfunction, leading to increased oxidative stress and the accumulation of reactive oxygen species (ROS). This cascade ultimately triggers cell death through mechanisms such as autophagy and mitophagy. Autophagy constitutes a crucial catabolic mechanism within eukaryotic cells, facilitating the degradation and recycling of damaged, aged, or superfluous organelles and proteins via the lysosomal pathway. This process is essential for maintaining cellular homeostasis and adapting to diverse stress conditions. As a cellular self-degradation and clearance mechanism, autophagy exhibits a dualistic function: it can confer protection during the initial phases of cellular injury, yet potentially exacerbate damage in the later stages. This paper aims to elucidate the fundamental mechanisms of autophagy in I/R injury, highlighting its dual role in regulation and its effects on both organ-specific and systemic responses. By comprehending the dual mechanisms of autophagy and their implications for organ function, this study seeks to explore the potential for therapeutic interventions through the modulation of autophagy within clinical settings.

Keywords:  Apoptosis; Autophagy; I/R injury; Mitophagy; Necroptosis

DOI:  https://doi.org/10.1186/s11658-025-00713-x
Stem Cell Res Ther. 2025 Apr 05. 16(1): 163

Interactions among Merlin, Arkadia, and SKOR2 mediate NF2-associated human Schwann cell proliferation.

Pei-Ciao Tang, Seyoung Um, Anderson B Mayfield, Olena R Bracho, Christian Del Castillo, Christine T Dinh, Derek M Dykxhoorn, Xue Zhong Liu.

   BACKGROUND: NF2-related Schwannomatosis (previously referred to as Neurofibromatosis Type 2, or NF2) is a genetic-associated disease resulting from mutations in the gene, NF2. NF2 encodes the Merlin protein, which acts as a tumor suppressor. Bilateral vestibular schwannoma (VS) is a hallmark of NF2. Although the exactly molecular mechanism mediating NF2-driven schwannomatosis is not fully understood, it is known that defective Merlin protein functionality leads to abnormal cell proliferation.
METHODS: Herein, we utilized a human induced pluripotent stem cell (hiPSC)-based Schwann cell (SC) model to investigate the role of Merlin in human SCs. SCs were derived from hiPSCs carrying a NF2 mutation (c.191 T > C; p. L64P), its isogenic wild-type control cell line, and a NF2 patient-derived hiPSC line. Phenotypes were determined via immunocytochemistry and various bioassays. Different proteins interacting with Merlin in wild-type and NF2 mutation SCs were identified using co-immunoprecipitation followed by mass spectrometry.
RESULTS: SC derived from NF2L64P hiPSCs showed significantly higher proliferation and abnormal morphology compared to NF2WT SCs. Phenotypes that could be restored by wildtype NF2 overexpression. Interactome profiling of Merlin (NF2) in SCs derived from NF2WT- and NF2L64P- hiPCSs identified differential protein binding levels. Among identified proteins, we validated the interaction among Merlin, an E3 ubiquitin ligase (Arkadia), and a SKI family co-repressor (SKOR2). This complex plays a significant role for this interaction in SC proliferation. Our findings were further validated by SCs derived from the patient-derived hiPSCs carrying a deletion in the chromosome 22 which spans the NF2 gene.
CONCLUSIONS: Our results presented a hiPSC-derived SC system for SC-related disease modeling and established a new model in which Merlin interacts with Arkadia and SKOR2. This interaction is required for the proper cell proliferation in human SCs.

Keywords:  Human induced pluripotent stem cells; Merlin; NF2; Proteomic analysis; Schwann cells; Schwannoma

DOI:  https://doi.org/10.1186/s13287-025-04281-x
Sci Rep. 2025 Apr 09. 15(1): 12106

Genome editing in spinocerebellar ataxia type 3 cells improves Golgi apparatus structure.

Yanlin Wang, Yunan Cheng, Huifang Sun, Zhuoya Wang, Na Chen, Changhe Shi, Han Liu, Jing Yang, Yuming Xu.

  Spinocerebellar ataxia type 3 (SCA3) is an autosomal dominant neurodegenerative disease caused by repeat expansion of the CAG trinucleotide within exon 10 of the ATXN3 gene. This mutation results in the production of an abnormal ataxin-3 protein containing an extended polyglutamine tract, referred to as mutant ataxin-3. In this study, we investigated the therapeutic potential of CRISPR/Cas9-mediated genome editing for SCA3. First, we designed a specific single-guide RNA targeting the ATXN3 gene and constructed the corresponding targeting vector. Induced pluripotent stem cells (iPSCs) derived from a SCA3 patient were then electroporated with the CRISPR/Cas9 components. Positive clones were screened and validated by PCR and Sanger sequencing to obtain genome-editing iPSCs (GE-iPSCs). Subsequently, the pluripotency of GE-iPSCs was confirmed, and the effects of genome editing on mutant ataxin-3 protein expression and Golgi apparatus morphology were assessed using Western blotting and immunofluorescence analyses. Our results demonstrated that targeted insertion of polyadenylation signals (PAS) upstream of the abnormal CAG repeats effectively suppressed the production of mutant ataxin-3. This intervention also reduced the formation of neuronal nuclear inclusions in differentiated neurons, restored the structural integrity of the Golgi apparatus (which exhibited a loose and enlarged morphology in SCA3 cells), and increased the expression levels of Golgi structural proteins (GM130 and GORASP2). In conclusion, our findings indicate that the targeted insertion of PAS upstream of the abnormal CAG repeats in the ATXN3 gene represents a promising therapeutic strategy for SCA3 through genome editing.

Keywords:  CRISPR/Cas9; Genome editing; Golgi apparatus; Spinocerebellar ataxia type 3

DOI:  https://doi.org/10.1038/s41598-025-93369-8
J Biol Chem. 2025 Apr 09. pii: S0021-9258(25)00351-5. [Epub ahead of print] 108502

α-Synuclein interacts directly with AP2 and regulates its binding to synaptic membranes.

Karina J Vargas, Jaqulin N Wallace, Ian Mooney, David J Owen, Jennifer R Morgan.

  α-Synuclein mutation and aggregation are associated with several neurodegenerative disorders, including Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. It is expressed in the presynaptic compartment where it regulates clathrin mediated synaptic vesicle endocytosis. We have shown that α-synuclein regulates clathrin lattice size and curvature in vitro. However, the molecular mechanism by which this occurs remains unknown. Here, we show a strong colocalization between the heterotetrametric clathrin adaptor protein-2 (AP2) and α-synuclein at presynapses. Moreover, we report a direct biochemical interaction between the AP2 core domain and the C-terminal domain of α-synuclein. We further show that α-synuclein binds to isolated synaptic membranes in an ATP-dependent manner, similar to AP2 and the monomeric adaptor protein, 180 KDa (AP180), suggesting that α-synuclein, AP2 and AP180 share a common synaptic membrane binding pathway. In contrast, other endocytic proteins, such as clathrin heavy chain and the large GTPase dynamin-1 bind to synaptic membranes independently of ATP. After immunodepleting α-synuclein, we observed a specific reduction in AP2 binding to synaptic membranes, indicating that α-synuclein interaction with AP2 is necessary to maintain normal levels of AP2 on synaptic membranes. These findings demonstrate that α-synuclein plays a critical role in stabilizing AP2 on synaptic membranes, an event which is required for initiation of clathrin-mediated synaptic vesicle endocytosis.

Keywords:  AP2; endocytosis; synapse; synaptic vesicle recycling; α-synuclein

DOI:  https://doi.org/10.1016/j.jbc.2025.108502
Open Vet J. 2025 Feb;15(2): 804-812

In vitro model of ischemic stroke neurons from Macaca fascicularis.

Ratih Rinendyaputri, Sela Septima Mariya, Dany Frans, Ariyani Noviantari, Dwi Budiono, Lisa Andriani Lienggonegoro, Hasta Handayani Idrus, Wireni Ayuningtyas, Rachmawati Noverina, Fathul Huda, Ahmad Faried.

   Background: Primary cells have the same heterogeneity and differentiation capacity that has potential as an in vitro ischemic stroke models. It is hoped that primary cells from non-human primates that have genetic similarities to humans can provide molecular information and become more accurate data for use in drug screening, especially stroke therapy. B27 is a supplement commonly used in neuronal cell cultures, but there are concerns that its effects will interfere with the neuroprotective processes of the drug candidates being tested.
Aim: This research will prove the demonstration of neurons as an ischemic stroke model and the effects of B27 in Macaca fascicularis (Mf) neurons as a model for ischemic stroke under oxygen glucose deprivation (OGD).
Methods: Neurons were obtained from a collection of biological materials collected during previous research. Neuronal validation was performed using immunocytochemistry with the marker β-tubulin. Expression of the apoptotic response was performed by real time- polymerase chain reaction/(RT-PCR) using Bax, BCL-2, caspase-9, and p53 gene markers. Characterization of neurons in terms of positive tβubulin markers and induction of OGD in neurons can be performed for 6 h to model ischemic stroke.
Results: This study showed that cultured neurons under OGD conditions can experience apoptosis, namely by increasing pro-apoptosis and decreasing anti-apoptosis. However, B27 supplementation increased the expression of anti-apoptotic Bcl-2 genes and decreased proapoptotic genes such as Bax, caspase 9, and p53.
Conclusion: Neuron culture from Mf can be used as an in vitro model of ischemic stroke, and B27 supplementation in neurons exerts neuroprotective effects on the induction of OGD.

Keywords:  Ischemic stroke; Macaca fascicularis; Neuron; OGD; Oxygen glucose deprivation

DOI:  https://doi.org/10.5455/OVJ.2025.v15.i2.29
J Cell Biol. 2025 May 05. pii: e202502030. [Epub ahead of print]224(5):

Rab GTPases as "eat me" signals for selective autophagy.

Yan G Zhao.

Selective autophagy targets specific cellular cargo for degradation. In this issue, Zhao et al. (https://doi.org/10.1083/jcb.202410150) uncovered that Rab GTPases serve as pivotal "autophagy cues" for recruitment of cargo receptors to facilitate mitophagy, lipophagy, and xenophagy, contributing to the precise spatiotemporal regulation of selective autophagy.

DOI: https://doi.org/10.1083/jcb.202502030
Cell. 2025 Apr 04. pii: S0092-8674(25)00282-X. [Epub ahead of print]

Quiescent cell re-entry is limited by macroautophagy-induced lysosomal damage.

Andrew Murley, Ann Catherine Popovici, Xiwen Sophie Hu, Anina Lund, Kevin Wickham, Jenni Durieux, Larry Joe, Etai Koronyo, Hanlin Zhang, Naomi R Genuth, Andrew Dillin.

  To maintain tissue homeostasis, many cells reside in a quiescent state until prompted to divide. The reactivation of quiescent cells is perturbed with aging and may underlie declining tissue homeostasis and resiliency. The unfolded protein response regulators IRE-1 and XBP-1 are required for the reactivation of quiescent cells in developmentally L1-arrested C. elegans. Utilizing a forward genetic screen in C. elegans, we discovered that macroautophagy targets protein aggregates to lysosomes in quiescent cells, leading to lysosome damage. Genetic inhibition of macroautophagy and stimulation of lysosomes via the overexpression of HLH-30 (TFEB/TFE3) synergistically reduces lysosome damage. Damaged lysosomes require IRE-1/XBP-1 for their repair following prolonged L1 arrest. Protein aggregates are also targeted to lysosomes by macroautophagy in quiescent cultured mammalian cells and are associated with lysosome damage. Thus, lysosome damage is a hallmark of quiescent cells, and limiting lysosome damage by restraining macroautophagy can stimulate their reactivation.

Keywords:  aging; endoplasmic reticulum; lysosome; mTOR; macroautophagy; protein aggregates; quiescence

DOI:  https://doi.org/10.1016/j.cell.2025.03.009
J Cell Biol. 2025 Jun 02. pii: e202411092. [Epub ahead of print]224(6):

The autophagy protein ATG-9 regulates lysosome function and integrity.

Kangfu Peng, Guoxiu Zhao, Hongyu Zhao, Nobuo N Noda, Hong Zhang.

The transmembrane autophagy protein ATG9 has multiple functions essential for autophagosome formation. Here, we uncovered a novel function of ATG-9 in regulating lysosome biogenesis and integrity in Caenorhabditis elegans. Through a genetic screen, we identified that mutations attenuating the lipid scrambling activity of ATG-9 suppress the autophagy defect in epg-5 mutants, in which non-degradative autolysosomes accumulate. The scramblase-attenuated ATG-9 mutants promote lysosome biogenesis and delivery of lysosome-localized hydrolases and also facilitate the maintenance of lysosome integrity. Through manipulation of phospholipid levels, we found that a reduction in phosphatidylethanolamine (PE) also suppresses the autophagy defects and lysosome damage associated with impaired lysosomal degradation. Our results reveal that modulation of phospholipid composition and distribution, e.g., by attenuating the scramblase activity of ATG-9 or reducing the PE level, regulates lysosome function and integrity.

DOI: https://doi.org/10.1083/jcb.202411092
J Vis. 2025 Apr 01. 25(5): 28

Poster Session: Abnormal GSK3β activity affects Drosophila vision.

Oscar Solis, Alex Wade, Ines Hahn.

The enzyme, glycogen synthase kinase 3β (GSK3β), plays a key role in the development and maintenance of axons in neurons. Recent work has revealed microtubule (MT) unbundling in the axons of neurons with overactive or inactive GSK3β and it is hypothesised that this phenotype is tightly related to impaired axonal transport and synaptic defects. To test whether abnormal GSK3β activity affects neuronal function, the Drosophila visual system was probed using the steady-state visually evoked potential (SSVEP) technique. This involved recording electrophysiological responses from the fly eye presented with stimuli consisting of flickering light. Analyses revealed abnormal visual responses in flies expressing overactive or inactive GSK3β compared to control flies. To test whether this was due to MT unbundling, flies were fed with the MT-stabilising drug, Epothilone B (EpoB). The drug did not rescue the visual defects but instead led to adverse effects. Taken together, these results suggest that GSK3β dysregulation leads to neuronal dysfunction in the fly visual system, but MT unbundling may not be the sole mechanism underlying these visual defects.

DOI: https://doi.org/10.1167/jov.25.5.28
Mol Cell. 2025 Mar 27. pii: S1097-2765(25)00201-1. [Epub ahead of print]

STING mediates lysosomal quality control and recovery through its proton channel function and TFEB activation in lysosomal storage disorders.

Zhen Tang, Cong Xing, Antonina Araszkiewicz, Kun Yang, Wanwan Huai, Devon Jeltema, Nicole Dobbs, Yihe Zhang, Lu O Sun, Nan Yan.

  Lysosomes are essential organelles for cellular homeostasis. Defective lysosomes are associated with diseases like lysosomal storage disorders (LSDs). How lysosomal defects are detected and lysosomal function restored remain incompletely understood. Here, we show that STING mediates a neuroinflammatory gene signature in three distinct LSD mouse models, Galctwi/twi, Ppt1-/-, and Cln7-/-. Transcriptomic analysis of Galctwi/twi mouse brain tissue revealed that STING also mediates the expression of lysosomal genes that are regulated by transcriptional factor EB (TFEB). Immunohistochemical and single-nucleus RNA-sequencing (snRNA-seq) analysis show that STING regulates lysosomal gene expression in microglia. Mechanistically, we show that STING activation leads to TFEB dephosphorylation, nuclear translocation, and expression of lysosomal genes. This process requires STING's proton channel function, the V-ATPase-ATG5-ATG8 cascade, and is independent of immune signaling. Furthermore, we show that the STING-TFEB axis facilitates lysosomal repair. Together, our data identify STING-TFEB as a lysosomal quality control mechanism that responds to lysosomal dysfunction.

Keywords:  Krabbe disease; Niemann-Pick disease; STING; TFEB; innate immunity; lysosomal storage disorder; lysosome repair; neuroinflammation; non-canonical autophagy

DOI:  https://doi.org/10.1016/j.molcel.2025.03.008
Nat Rev Neurol. 2025 Apr 10.

Neurofilament light chain induces neuroinflammation.

Lisa Kiani.

DOI: https://doi.org/10.1038/s41582-025-01085-8