Neuroscience
Abstract
Demyelination associated microglia (DMAM) orchestrate the regenerative response to demyelination by clearing myelin debris and promoting oligodendrocyte maturation. Peroxisomal metabolism has emerged as a candidate regulator of DMAMs, though the cell-intrinsic contribution in microglia remains undefined. Here we elucidate the role of peroxisome integrity in DMAMs using cuprizone mediated demyelination coupled with conditional knockout of peroxisome biogenesis factor 5 (PEX5) in microglia. Absent demyelination, PEX5 conditional knockout (PEX5cKO) had minimal impact on homeostatic microglia. However, during cuprizone-induced demyelination, the emergence of DMAMs unmasked a critical requirement for peroxisome integrity. At peak demyelination, PEX5cKO DMAMs exhibited increased lipid droplet burden and reduced lipophagy suggestive of impaired lipid catabolism. Although lipid droplet burden declined during the remyelination phase, PEX5cKO DMAMs accumulated intralysosomal crystals and curvilinear profiles, which features were largely absent in controls. Aberrant lipid processing was accompanied by elevated lysosomal damage markers and downregulation of the lipid exporter gene Apoe, consistent with defective lipid clearance. Furthermore, the disruptions in PEX5cKO DMAMs were associated with defective myelin debris clearance and impaired remyelination. Together, these findings delineate a stage-specific role for peroxisomes in coordinating lipid processing pathways essential to DMAM function and necessary for enabling a pro-remyelinating environment.
Authors
Joseph A. Barnes-Vélez, Xiaohong Zhang, Yaren L. Peña Señeriz, Kiersten A. Scott, Yinglu Guan, Jian Hu
Abstract
BACKGROUND. Amyotrophic lateral sclerosis (ALS), the major adult-onset motor neuron disease, is preceded by an early period unrelated to motor symptoms, including altered sleep, with increased wakefulness and decreased deep NREM. Whether these alterations in sleep macroarchitecture are associated with, or even precede abnormalities in sleep-related EEG features remains unknown. METHODS. Here, we characterised sleep microarchitecture using polysomnography in patients with ALS (n=33) and controls (n=32), and in asymptomatic carriers of SOD1 or C9ORF72 mutations (n=57) and non-carrier controls (n=30). Patients and controls with factors that could confound sleep structure, including respiratory insufficiency, were prospectively excluded. Results were complemented in three ALS mouse models (Sod1G86R , Fus∆NLS/+ and TDP-43Q331K ). RESULTS. We observed a brain-wide reduction in the density of sleep spindles, slow oscillations and K-complexes in both early-stage ALS patients and presymptomatic gene carriers. These defects in sleep spindles and slow oscillations correlate with cognitive performance in both cohorts, particularly with scores on memory, verbal fluency and language function. Alterations in sleep microarchitecture were replicated in three mouse models and decreases in sleep spindles were rescued following intracerebroventricular supplementation of MCH or by the oral administration of a dual orexin receptor antagonist. CONCLUSION. Sleep microarchitecture is associated with cognitive deficits and is causally linked to aberrant MCH and orexin signalling in ALS. FUNDING. This work was funded by Agence Nationale de la Recherche (ANR-24-CE37-4064, ANR-10-IDEX-0002, ANR-20-SFRI-0012), Fondation Thierry Latran, Association Francaise de Recherche sur la sclérose latérale amyotrophique, Association Française contre les Myopathies (#28944), TargetALS and JPND.
Authors
Christina Lang, Simon J. Guillot, Dorothee Lule, Luisa T. Balz, Antje Knehr, Patrick Weydt, Johannes Dorst, Katharina Kandler, Hans-Peter Müller, Jan Kassubek, Laura Wassermann, Sandrine Da Cruz, Francesco Roselli, Albert C. Ludolph, Matei Bolborea, Luc Dupuis
Abstract
The increased prevalence of GluA2-lacking, Ca2+-permeable AMPA receptors (CP-AMPARs) at spinal cord sensory synapses amplifies nociceptive transmission and maintains chronic neuropathic pain. Nerve injury–induced upregulation of α2δ-1 disrupts the assembly of GluA1/GluA2 heteromers, favoring the synaptic incorporation of GluA1 homotetramers in the spinal dorsal horn. Although GluA1-GluA3 subunits are broadly expressed, whether α2δ-1 regulates GluA3-containing AMPARs remains unknown. Here, we unexpectedly found that coexpression with α2δ-1—but not α2δ-2 or α2δ-3—diminished GluA3 AMPAR currents and protein levels, an effect blocked by pregabalin, an α2δ-1 C-terminus peptide, or proteasome inhibition. Both nerve injury and α2δ-1 overexpression reduced protein levels of GluA3 and GluA2/GluA3 heteromers in the spinal cord. Furthermore, α2δ-1 coexpression or nerve injury increased GluA3 ubiquitination, with Lys-861 at the C terminus of GluA3 identified as a key ubiquitination site mediating α2δ-1–induced GluA3 degradation. Additionally, intrathecal delivery of the Gria3 gene reversed nerve injury–induced nociceptive hypersensitivity and synaptic CP-AMPARs by restoring protein levels of GluA3 and GluA2/GluA3 heteromers in the spinal cord. These findings reveal that α2δ-1 promotes GluA1 homotetramer assembly and synaptic CP-AMPAR expression by driving ubiquitin-proteasomal degradation of GluA3, providing insights into the molecular mechanisms of neuropathic pain and the therapeutic actions of gabapentinoids.
Authors
Meng-Hua Zhou, Shao-Rui Chen, Daozhong Jin, Yuying Huang, Hong Chen, Guanxing Chen, Jiusheng Yan, Hui-Lin Pan
Abstract
Sympathetic tone is a central signaling axis inhibiting osteogenesis; however, the combination of durable local and systemic sympathetic effects on bone argues that multiple mechanisms, including yet-undiscovered pathways, are involved. Here, we found that sympathetic nerves constituted a component of the skeletal stem cell (SSC) niche: mice with conditional deletion of the classical axonal repellent Slit2 in sympathetic nerves (Slit2th mice), but not in bone stem/progenitor cells or sensory nerves, showed osteopenia due to an increase in sympathetic innervation and an associated decrease in SSCs. Mice with increased skeletal sympathetic innervation displayed impaired SSC niche function in an SSC orthotopic transplantation and engraftment system. Follistatin-like 1 (FSTL1) is a SLIT2-regulated soluble factor suppressing SSC self-renewal and osteogenic capacity. Accordingly, ablation of Fstl1 in sympathetic neurons enhanced SSC-driven osteogenesis and attenuated the bone loss seen in Slit2th mice. Together, the findings indicate that SLIT2 is a regulator of a sympathetic nerve–mediated SSC niche.
Authors
Zuoxing Wu, Na Li, Zhengqiong Luo, Zihan Chen, Xuemei He, Jie Han, Xixi Lin, Fan Shi, Haitao Huang, Baohong Shi, Yu Li, Xin Wang, Lin Meng, Dachuan Zhang, Lanfen Chen, Dawang Zhou, Weinan Cheng, Matthew B. Greenblatt, Ren Xu
Abstract
Charcot-Marie-Tooth Disease is a clinically and genetically heterogeneous group of hereditary neuropathies. Despite progress in genetic sequencing, around a quarter of patients remain unsolved. Here, we identify 16 recessive variants in the RhoGTPase activating protein 19 gene (ARHGAP19) causing motor-predominant neuropathy in 25 individuals from 20 unrelated families. The ARHGAP19 protein acts as a negative regulator of the RhoA GTPase. In vitro biochemical and cellular assays revealed that patient variants impair the GTPase-activating protein (GAP) activity of ARHGAP19 and reduce ARHGAP19 protein levels. Combined in vitro and in vivo studies reveal that human ARHGAP19, and conserved ARHGAP19 orthologs in Drosophila and Zebrafish, influence motoneuron morphology and promote locomotor capacity. Transcriptomic studies further demonstrate that ARHGAP19 regulates cellular pathways associated with motor proteins and the cell cycle. Taken together, our findings establish ARHGAP19 variants as a cause of inherited neuropathy acting through a loss-of-function mechanism.
Authors
Natalia Dominik, Stephanie Efthymiou, Christopher J. Record, Xinyu Miao, Renee Q. Lin, Jevin M. Parmar, Annarita Scardamaglia, Reza Maroofian, Simon A. Lowe, Gabriel N. Aughey, Abigail D. Wilson, Riccardo Curro, Ricardo P. Schnekenberg, Shahryar Alavi, Leif Leclaire, Yi He, Kristina Zhelcheska, Yohanns Bellaiche, Isabelle Gaugué, Mariola Skorupinska, Liedewei Van de Vondel, Sahar I. Da'as, Valentina Turchetti, Serdal Güngör, Gavin V. Monahan, Ehsan Ghayoor Karimiani, Yalda Jamshidi, Phillipa J. Lamont, Camila Armirola-Ricaurte, Haluk Topaloglu, Albena Jordanova, Mashaya Zaman, Selina H. Banu, Wilson Marques, Pedro J. Tomaselli, Busra Aynekin, Ali Cansu, Huseyin Per, Ayten Güleç, Javeria Raza Alvi, Tipu Sultan, Arif Khan, Giovanni Zifarelli, Shahnaz Ibrahim, Grazia M. S. Mancini, M.M. Motazacker, Esther Brusse, Vincenzo Lupo, Teresa Sevilla, A. Nazli Başak, Seyma Tekgul, Robin J. Palvadeau, Jonathan Baets, Yesim Parman, Arman Çakar, Rita Horvath, Tobias B. Haack, Jan-Hendrik Stahl, Kathrin Grundmann-Hauser, Joohyun Park, Stephan Zuchner, Nigel G. Laing, Lindsay A. Wilson, Alexander M. Rossor, James Polke, Fernanda Barbosa Figueiredo, André Pessoa, Fernando Kok, Antônio Rodrigues Coimbra-Neto, Marcondes C. Franca Jr, Gianina Ravenscroft, Sherifa A. Hamed, Wendy K. Chung, Alan M. Pittman, Daniel P. Osborn, Michael Hanna, Andrea Cortese, Mary M. Reilly, James E.C. Jepson, Nathalie Lamarche-Vane, Henry Houlden
Abstract
Chronic pain is a complex clinical problem comprising multiple conditions that may share a common genetic profile. Genome-wide association studies (GWAS) have identified many risk loci whose cell-type context remains unclear. Here, we integrated GWAS data on chronic pain (N = 1,235,695) with single-cell RNA sequencing (scRNA-seq) data from human brain and dorsal root ganglia (hDRG), and single-cell chromatin accessibility data from human brain and mouse dorsal horn. Pain-associated variants were enriched in glutamatergic neurons; mainly in prefrontal cortex, hippocampal CA1-3, and amygdala. In hDRG, the hPEP.TRPV1/A1.2 neuronal subtype showed robust enrichment. Chromatin accessibility analyses revealed variant enrichment in excitatory and inhibitory neocortical neurons in brain and in midventral neurons and oligodendrocyte precursor cells in the mouse dorsal horn. Gene-level heritability in the brain highlighted roles for kinase activity, GABAergic synapses, axon guidance, and neuron projection development. In hDRG, implicated genes related to glutamatergic signaling and neuronal projection. In cervical DRG of patients with acute or chronic pain (N = 12), scRNA-seq data from neuronal or non-neuronal cells were enriched for chronic pain-associated genes (e.g., EFNB2, GABBR1, NCAM1, SCN11A). This cell-type-specific genetic architecture of chronic pain across central and peripheral nervous system circuits provides a foundation for targeted translational research.
Authors
Sylvanus Toikumo, Marc Parisien, Michael J. Leone, Chaitanya Srinivasan, Huasheng Yu, Asta Arendt-Tranholm, Úrzula Franco-Enzástiga, Christoph Hofstetter, Michele Curatolo, Wenqin Luo, Andreas R. Pfenning, Rebecca P. Seal, Rachel L. Kember, Theodore J. Price, Luda Diatchenko, Stephen G. Waxman, Henry R. Kranzler
Abstract
Deficits in the mitochondrial energy-generating machinery cause mitochondrial disease (MD), a group of untreatable and usually fatal disorders. Among many severe symptoms, refractory epileptic events are a common neurological presentation of MD. However, the neuronal substrates and circuits for MD-induced epilepsy remain unclear. Here, using mouse models of Leigh Syndrome, a severe form of MD associated to epilepsy, that lack mitochondrial complex I subunit NDUFS4 in a constitutive or conditional manner, we demonstrate that mitochondrial dysfunction leads to a reduction in the number of GABAergic neurons in the rostral external globus pallidus (GPe), and identify a specific affectation of pallidal Lhx6-expressing inhibitory neurons, contributing to altered GPe excitability. Our findings further reveal that viral vector-mediated Ndufs4 re-expression in the GPe effectively prevents seizures and improves the survival in the models. Additionally, we highlight the subthalamic nucleus (STN) as a critical structure in the neural circuit involved in mitochondrial epilepsy, as its inhibition effectively reduces epileptic events. Thus, we have identified a role for pallido-subthalamic projections in the development of epilepsy in the context of mitochondrial dysfunction. Our results suggest STN inhibition as a potential therapeutic intervention for refractory epilepsy in patients with MD providing promising leads in the quest to identify effective treatments.
Authors
Laura Sánchez-Benito, Melania González-Torres, Irene Fernández-González, Laura Cutando, María Royo, Joan Compte, Miquel Vila, Sandra Jurado, Elisenda Sanz, Albert Quintana
Abstract
BACKGROUND Inter- and intraindividual fluctuations in pain intensity pose a major challenge to treatment efficacy, with a majority of people perceiving their pain relief as inadequate. Recent preclinical studies have identified circadian rhythmicity as a potential contributor to these fluctuations and a therapeutic target.METHODS We therefore sought to determine the impact of circadian rhythms in people with chronic low back pain (CLBP) through a detailed characterization, including questionnaires to evaluate biopsychosocial characteristics, ecological momentary assessment (7 day e-diaries at 8:00/14:00/20:00) to observe pain fluctuations, and intraday blood transcriptomics (at 8:00/20:00) to identify genes/pathways of interest.RESULTS While most individuals displayed constant or variable/mixed pain phenotypes, a distinct subset had daily fluctuations of increasing pain scores (>30% change in intensity over 12 hours in ≥4/7 days). This population had no opioid users, better biopsychosocial profiles, and differentially expressed transcripts relative to other pain phenotypes. The circadian-governed neutrophil degranulation pathway was particularly enriched among arrhythmic individuals; the link between neutrophil degranulation and opioid use was further confirmed in a separate CLBP cohort.CONCLUSION Our findings identified pain rhythmicity and the circadian expression of neutrophil degranulation pathways as indicators of CLBP outcomes, which may help provide a personalized approach to phenotyping biopsychosocial characteristics and medication use. This highlights the need to better understand the impact of circadian rhythmicity across chronic pain conditions.FUNDING This work was funded by grants from the Canadian Institutes of Health Research (CIHR; grant PJT-190170, to NG and MGP) and the CIHR-Strategy for Patient-Oriented Research Chronic Pain Network (grant SCA-145102, to NG, QD, LD, MGP, and MC). DT was funded by a MS Canada endMS Doctoral Research Award, AMZ by an Ontario Graduate Scholarship, HGMG by a CIHR Doctoral Research Award, MGP by a Junior 2 Research Scholarship from the Fonds de recherche du Québec – Santé, and LD by a Canadian Excellence Research Chairs and Pfizer Canada Professorship in Pain Research.
Authors
Doriana Taccardi, Amanda M. Zacharias, Hailey G.M. Gowdy, Mitra Knezic, Marc Parisien, Etienne J. Bisson, Zhi Yi Fang, Sara A. Stickley, Elizabeth Brown, Daenis Camiré, Rosemary Wilson, Lesley N. Singer, Jennifer Daly-Cyr, Manon Choinière, Zihang Lu, M. Gabrielle Pagé, Luda Diatchenko, Qingling Duan, Nader Ghasemlou
Abstract
Whether amyloid-β (Aβ) peptides are synaptogenic or synaptotoxic remains a pivotal open question in Alzheimer’s disease research. Here, we chronically treated human neurons with precisely controlled concentrations of chemically defined synthetic Aβ40, Aβ42, and Aβ42arctic peptides that exhibit distinct aggregation propensities. Remarkably, chronic exposure of human neurons to free Aβ40 at higher concentrations or to free Aβ42 at lower concentrations potently promoted synapse formation. In contrast, aggregated Aβ42 or Aβ42arctic at higher concentrations were neurotoxic and synaptotoxic. The synaptotoxic effects of Aβ peptides manifested as an initial contraction of the synaptic vesicle cluster followed by synapse loss. Aβ40 and Aβ42 peptides with scrambled or inverted sequences were inactive. Thus, our experiments reveal that Aβ peptides exhibit an aggregation-dependent functional dichotomy that renders them either synaptogenic or synaptotoxic, thereby providing insight into how Aβ peptides straddle a thin line between physiological synapse organization and pathological synapse disruption. Among others, our data suggest that Alzheimer’s disease therapies might aim to shift the balance of Aβ peptides from the aggregated to the free state instead of suppressing all Aβ peptides.
Authors
Alberto Siddu, Silvia Natale, Connie H. Wong, Hamidreza Shaye, Thomas C. Südhof
Abstract
The Integrator complex plays essential roles in RNA polymerase II transcription termination and RNA processing. Here, we identify INTS6, a subunit of the Integrator complex, as a novel gene associated with neurodevelopmental disorders (NDDs). Through analysis of large NDD cohorts and international collaborations, we identified 23 families harboring monoallelic likely gene-disruptive or de novo missense variants in INTS6. Phenotypic characterization revealed shared features, including language and motor delays, autism, intellectual disability, and sleep disturbances. Using a nervous-system conditional knockout (cKO) mouse model, we show that Ints6 deficiency disrupts early neurogenesis, cortical lamination, and synaptic development. Ints6 cKO mice displayed a thickened ventricular zone/subventricular zone, thinning of the cortical plate, reduced neuronal differentiation, and increased apoptosis in cortical layer 6. Behavioral assessments of heterozygous mice revealed deficits in social novelty preference, spatial memory, and hyperactivity, mirroring phenotypes observed in individuals with INTS6 variants. Molecular analyses further revealed that INTS6 deficiency alters RNA polymerase II dynamics, disrupts transcriptional regulation, and impairs synaptic gene expression. Treatment with a CDK9 inhibitor (CDK9i) reduced RNAPII phosphorylation, thereby limiting its binding to target genes. Notably, CDK9i reversed neurosphere over-proliferation and rescued the abnormal dendritic spine phenotype caused by Ints6 deficiency. This work advances understanding of INTS-related NDD pathogenesis and highlights potential therapeutic targets for intervention.
Authors
Xiaoxia Peng, Xiangbin Jia, Hanying Wang, Jingjing Chen, Xiaolei Zhang, Senwei Tan, Xinyu Duan, Can Qiu, Mengyuan Hu, Haiyan Hou, Ilaria Parenti, Alma Kuechler, Frank J. Kaiser, Alicia Renck, Raymond Caylor, Cindy Skinner, Joseph Peeden, Benjamin Cogne, Bertrand Isidor, Sandra Mercier, Gael Nicolas, Anne-Marie Guerrot, Flavio Faletra, Luciana Musante, Lior Cohen, Gaber Bergant, Goran Čuturilo, Borut Peterlin, Andrea Seeley, Kristine Bachman, Julian A. Martinez-Agosto, Conny van Ravenswaaij-Arts, Dennis Bos, Katherine H. Kim, Tobias Bartolomaeus, Zelia Schmederer, Rami Abou Jamra, Erfan Aref-Eshghi, Wenjing Zhao, Yongyi Zou, Zhengmao Hu, Qian Pan, Faxiang Li, Guodong Chen, Jiada Li, Zhangxue Hu, Kun Xia, Jieqiong Tan, Hui Guo
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)