Neuroscience
Abstract
BACKGROUND. Axonal degeneration is believed to be an early hallmark of Alzheimer’s disease (AD). This study investigated the temporal trajectory of axonal loss and its association with cognitive and functional decline using diffusion MRI-derived Axonal Density Index (dMRI-ADI). METHODS. Longitudinal dMRI, CSF and PET data from the ADNI were analyzed, including 117 cognitively normal (CN) and 88 impaired (CI) subjects, consisting of 74 mild cognitive impairment (MCI) and 14 AD individuals. Linear mixed-effects models examined group differences as well as associations between baseline and longitudinal changes in ADI, CSF or PET biomarkers and clinical outcomes. Results derived from larger CSF (n=527) and PET (tau-PET: n=870; amyloid-PET: n=1581) data were also presented. RESULTS. Compared to CN, the CI group exhibited significantly lower baseline ADI values and steeper longitudinal decline (p<10–⁶). Lower baseline ADI predicted faster cognitive and functional decline in the CI group (MMSE: p=0.03; CDR-SB: p<10–⁴), and longitudinal decreases in ADI were associated with worsening clinical outcomes (MMSE: p=0.001; CDR-SB: p<10–¹²). Compared to CSF and PET biomarkers, ADI demonstrated superior sensitivity in tracking disease progression and matched these biomarkers in predicting future cognitive and functional decline. Furthermore, decreases in ADI were significantly associated with declines in clinical outcomes; an association observed only with amyloid-PET, but not CSF biomarkers. CONCLUSION. Axonal degeneration is an early and clinically meaningful feature of AD. ADI is a promising noninvasive biomarker for early detection, prognosis, and disease monitoring. TRIAL REGISTRATION. ClinicalTrials.gov NCT00106899. FUNDING. This work was supported by the National Institute on Aging IRP.
Authors
Zhaoyuan Gong, John P. Laporte, Alexander Y. Guo, Murat Bilgel, Jonghyun Bae, Noam Y. Fox, Angelique de Rouen, Nathan Zhang, Aaliya Taranath, Rafael de Cabo, Josephine M. Egan, Luigi Ferrucci, Mustapha Bouhrara
Abstract
Epstein-Barr virus (EBV) is of growing interest for its potential role in neurodegenerative diseases such as multiple sclerosis (MS) and its possible utility as a therapeutic target in herpesvirus-associated chronic diseases. The effects of brincidofovir (BCV) on EBV reactivation were evaluated in vitro using EBV-infected spontaneous lymphoblastoid cell lines (SLCLs) and peripheral blood mononuclear cells (PBMCs) derived from MS patients and healthy controls. In addition, a B lymphoblastoid cell line and PBMCs from common marmosets (Callithrix jacchus) naturally infected with an EBV-related gammaherpesvirus (Callitrichine herpesvirus 3, CalHV-3) were used to measure BCV efficacy in a nonhuman primate model. BCV significantly inhibited gammaherpesvirus reactivation, with decreased lytic and latent viral transcript expression. These results suggest that BCV may be a useful antiviral for inhibiting EBV activity in MS patients. Additionally, this work further validates the utility of CalHV-3 in marmosets as a translational model for the investigation of successful EBV-targeting therapeutics.
Authors
Abaigeal Donaldson, Madeleine R. Druker, Maria Chiara Monaco, Emily H. Stack, Paige Zimmerman, Amanda Lee, Izabela Bialuk, William Frazier, Irene Cortese, Heather Narver, Masatoshi Hazama, Fuminori Yoshida, Xiaofan Li, Laurie T. Krug, Stacey L. Piotrowski, Steven Jacobson
Abstract
Authors
Antonio Carlos Tallon-Cobos, Konstantinos Vazaios, Piotr Waranecki, Marliek van Hoesel, Annelisa M. Cornel, Benjamin Schwalm, Norman Mack, Ella de Boed, Jasper van der Lugt, Stefan Nierkens, Marcel Kool, Eelco W. Hoving, Dennis S. Metselaar, Esther Hulleman
Abstract
Disorders of GABRA3, the only epilepsy-associated GABA-A receptor subunit gene on the X chromosome, have eluded clinical clarity due to ambiguous inheritance patterns and variable phenotypes. The long-standing assumption that all pathogenic variants cause loss-of-function further obscured genotype-phenotype relationships and hindered progress. Here, we curated a cohort of individuals with a GABRA3 variant, integrating deep phenotyping, genotyping, family history, electrophysiology, with a targeted mouse model. Among 43 individuals with 19 GABRA3 variants, functional analyses revealed both gain- and loss-of-function effects, each linked to distinct clinical profiles. Gain-of-function variants were associated with severe, treatment-resistant epilepsy and severe-profound intellectual disability, disproportionately affecting males, who were often non-ambulant and had cortical visual impairment. Loss-of-function variants produced milder phenotypes, with epilepsy rarely observed; affected males showed behavioural issues and language delay, while females were unaffected carriers. Our gain-of-function (Gabra3Q242L/+) mouse model mirrored these sex-specific differences, showing increased seizure susceptibility, early death, and marked cortical hyperexcitability. These insights not only resolve longstanding uncertainties surrounding GABRA3 but also redefine how X-linked disorders are interpreted. They demonstrate that it is the functional impact of a variant, not its mere presence, that determines whether a condition manifests dominantly or recessively. This distinction carries important implications for genetic counselling, precision medicine, and the broader interpretation of X-linked neurodevelopmental disorders.
Authors
Katrine M. Johannesen, Khaing Phyu Aung, Vivian W.Y. Liao, Nathan L. Absalom, Han C. Chua, Xue N. Gan, Miaomiao Mao, Chaseley E. McKenzie, Hian M. Lee, Sebastian Ortiz, Rebecca C. Spillmann, Vandana Shashi, Rodney A. Radtke, Ghayda M. Mirzaa, P. Anne Weisner, Josue Flores Daboub, Caroline Hagedorn, Pinar Bayrak-Toydemir, Desiree DeMille, Jian Zhao, Nandita Bajaj, Yline Capri, Boris Keren, Miriam Schmidts, Ingrid M.B.H. van de Laar, Marjon A. van Slegtenhorst, Rafal Ploski, Marta Bogotko, Danielle K. Bourque, Ebba Alkhunaizi, Lauren Chad, Nada Quercia, Houda Elloumi, Ingrid M. Wentzensen, Michael C. Kruer, Pritha Bisarad, Carolina I. Galaz-Montoya, Violeta Rusu, Dominique Braun, Katie Angione, Jessica C. Win, Camilo Espinosa-Jovel, Pia Zacher, Konrad Platzer, Samuel F. Berkovic, Ingrid E. Scheffer, Mary Chebib, Guido Rubboli, Rikke S. Møller, Christopher A. Reid, Philip K. Ahring
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
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)