Neuroscience
Abstract
Cyclin-dependent kinase like 5 (CDKL5) is a serine-threonine kinase enriched in the mammalian brain whose loss of function causes a severe developmental and epileptic encephalopathy named CDKL5 Deficiency Disorder. We previously showed that CDKL5 phosphorylates the microtubule-associated protein MAP1S, but how this regulates microtubule-dependent functions is not well understood. To address this question, we generated MAP1S phosphomutant mice in which the CDKL5 phosphorylation sites S786 and S812 were mutated to alanine (MAP1S S786/812A; MAP1S SA). Using a microtubule cosedimentation assay, we found that dynein binding to microtubules was reduced in MAP1S SA and CDKL5 knockout (KO) brain lysates, and time-lapse imaging showed impaired dynein motility in dendrites from both genotypes. MAP1S SA mice also exhibited reduced AMPA receptor transport, dendritic spine density, and excitatory synapses, accompanied by anxiety-like behavior and motor, social, and memory deficits relevant to CDD. Mechanistically, MAP1S SA and CDKL5 KO neurons showed increased microtubule stability and reduced tubulin tyrosination, consistent with excessive MAP1S-mediated stabilization. Restoring tubulin tyrosination by expressing tubulin-tyrosine ligase rescued dynein transport defects. Together, these findings identify MAP1S phosphorylation as a critical regulator of microtubule dynamics and dynein-dependent transport.
Authors
André T. Lopes, Ondine Janiv, Suzanne Claxton, Sila K. Ultanir
Abstract
STXBP1 variants are a frequent cause of early-onset developmental and epileptic encephalopathies and related neurodevelopmental disorders, but the clinical interpretation of these variants remains a major challenge. Most reported STXBP1 missense variants are classified as variants of uncertain significance (VUS), complicating diagnosis, counseling, and patient eligibility for precision therapies. Here, we developed EpiPred, a gene-specific machine learning classifier that predicts the pathogenicity of STXBP1 missense variants and tests these predictions using empirical evidence from well-established cellular assays. Trained on a curated set of pathogenic and benign variants, EpiPred outperformed global prediction tools in accuracy, sensitivity, and specificity. We validated the model’s predictions using variant effect assays that measure protein abundance, solubility, stability, and interaction with the SNARE complex partner syntaxin 1. These biochemical readouts aligned closely with model outputs and enabled reclassification of several possibly misdiagnosed variants, which warrant further validation and clinical reevaluation. We deployed EpiPred in an interactive web application that allows clinicians, researchers, and patients to explore predictions for all possible STXBP1 missense variants. By identifying likely pathogenic STXBP1 variants, including those that may respond to emerging therapies such as protein stabilizers. By coupling gene-calibrated machine learning with orthogonal variant-effect assays and public deployment, EpiPred provides a transferable framework for VUS resolution, trial enrichment, and precision diagnosis across clinically actionable Mendelian disease genes.
Authors
Jeffrey D. Calhoun, Chengbing Wang, Carina G. Biar, Jonathan R. Gunti, John S. Lee, Aaron M. Geller, Jung H. Hong, Santiago Schnell, Louis T. Dang, Yu Wang, Jack M. Parent, Lori L. Isom, Michael D. Uhler, Heather C. Mefford, M. Elizabeth Ross, Vanessa Aguiar-Pulido, Gemma L. Carvill
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive motor neuron loss, skeletal muscle atrophy, paralysis, and eventually death. Mitochondrial dysfunction plays a pivotal role in ALS pathogenesis, although the precise pathogenic mechanisms remain elusive, and effective therapeutic strategies are extremely limited. In this study, we developed a small-molecule inhibitor, UA-30, which directly targets RalA, and explored its potential for the treatment of ALS. We found that when administered via oral gavage for 6 weeks following the onset of motor deficit, UA-30 extended lifespan and improved motor function of SOD1G93A mice, a model of ALS. UA-30 ameliorated motor neuron loss, neuroinflammation, fibrosis, and mitochondrial dysfunction, as evidenced by energy recovery, decreased oxidative stress, and enhanced mitophagy. Mechanistically, UA-30 inhibited RalA activity and thereby modulated ERK/FOXO3a signaling, which inhibited FOXO3a degradation via the ubiquitin-proteasome pathway; enhanced FOXO3a stability; and upregulated the expression of mitophagy-related genes in this ALS mouse model. The beneficial effects of UA-30 in ALS were abolished by overexpression of the constitutively active form of RalA (RalAG23V) or Mdivi-1 treatment. These findings support RalA inhibition as a therapeutic strategy for enhancing mitophagy and mitigating ALS-like pathology and support UA-30 as an orally active candidate for further preclinical development.
Authors
Bingge Zhang, Ye He, Ting Su, Xiaomei Li, Xiufen Zhang, Ruijuan Liu, Xiao Han, Ruiming Zhang, Chao Yang, Xinlei Liu, Qinghua Hou, Zaijun Zhang, Yongmei Xie, Gongping Liu, Xifei Yang
Abstract
GLP-1 receptor agonists (GLP1RAs) effectively reduce feeding to treat obesity, although nausea and other aversive side effects of these drugs can limit their use. Brainstem circuits that promote satiation and mediate the physiological control of body weight can be distinguished from those that cause aversion. It remains unclear whether brainstem Glp1r neurons contribute to the normal regulation of energy balance and whether GLP1RAs control appetite via circuits distinct from those that mediate aversive responses, however. Here, we silenced Glp1r neurons in the nucleus of the solitary tract or area postrema (NTSGlp1r or APGlp1r neurons, respectively) or restored their GLP1R signaling on an otherwise GLP1R-deficient background to determine physiological and pharmacological roles for each neuron population. Although NTSGlp1r neurons contributed to the normal restraint of food intake and body weight, they failed to mediate GLP1RA-dependent weight loss. In contrast, while we detected no role for APGlp1r neurons in physiological feeding, they mediated both the weight-lowering and aversive effects of GLP1RAs. Therefore, while non-aversive NTSGlp1r neurons control physiologic satiation they do not contribute to weight loss during GLP1RA treatment. Rather, APGlp1r neurons mediate both the weight-lowering and aversive effects of GLP1RAs, preventing the separation of their nauseating and weight-loss effects at a circuit level.
Authors
Warren T. Yacawych, Yi Wang, Guoxiang Zhou, Shad Hassan, Cagri Bodur, Elisabeth Walters, John G. Santinga, Frederike Sass, Martin deVaux, Stace Kernodle, Iris Wu, Jenny M. Brown, Dylan M. Belmont-Rausch, Alan C. Rupp, Abigail J. Tomlinson, Zitian Lin, Emma VanTongeren, Anna Secher, Kirsten Raun, Tune H. Pers, Randy J. Seeley, Martin G. Myers Jr., Weiwei Qiu
Abstract
Microglia play essential yet poorly understood roles in brain development, including axon guidance, regulation of neurogenesis, and pruning of neuronal projections. Congenital hydrocephalus (CH), characterized by enlarged cerebrospinal fluid (CSF)-filled ventricles, is a leading cause of pediatric brain surgery, but its molecular mechanisms remain unclear. We have identified what we believe to be novel, recurrent, damaging missense variants in the SH3-binding domain of the adaptor protein Growth Factor Receptor-Bound Protein 2 (GRB2) in unrelated patients with CH. GRB2 is significantly co-expressed with one of its known upstream receptor tyrosine kinase partners, CSF1R, in the developing human brain, particularly in a microglial subtype associated with regulation of neural stem cells. Immunoprecipitation validated GRB2-CSF1R binding in mouse microglial cells and human monocyte cell line. Cx3cr1-Grb2fl/fl mice engineered with conditional deletion of Grb2 in microglia exhibit congenital absence of microglia and early postnatal severe communicating (non-obstructive) hydrocephalus, mimicking GRB2-mutant patients. The severe ventriculomegaly of Cx3cr1-Grb2fl/fl mice is associated with both depletion of cerebral cortical neurons and impairment of glia-lymphatic-mediated CSF flow. Together, these findings implicate a role of GRB2 in microglia that could be essential for brain development and CSF homeostasis.
Authors
Phan Q. Duy, Benjamin C. Reeves, Huanxing Sun, Xueyan Peng, Pazhanichamy Kalailingam, Garrett Allington, Evan Dennis, Le Thi Hao, Lei Wang, David Rufino-Ramos, Shujuan Zhao, Qiang Li, Neel H. Mehta, William C. Davalan, Mason Blacker, Anthony J. Piscopo, Shozeb Haider, Baojian Fan, Kedous Y. Mekbib, Shuai Shao, Carol Nelson-Williams, TuKiet T. Lam, Benjamin P. Kleinstiver, Patricia L. Musolino, Seth L. Alper, Sheng Chih Jin, Erica L. Herzog, Kristopher T. Kahle
Abstract
Pain is a common and disabling feature of myotonic disorders, yet its biological basis remains poorly understood and no targeted analgesic therapies currently exist. Here, we demonstrate that skeletal muscle hyperexcitability is sufficient to initiate a persistent pain state independent of inflammation, nerve injury, or overt tissue damage. Using complementary pharmacological and genetic models of myotonia resulting from loss of the voltage-gated skeletal muscle chloride channel ClC-1 function, we show that transient and chronic myotonia produce robust mechanical, thermal, and cold hypersensitivity, as well as spontaneous pain-like behavior. Notably, pain-like behaviors induced by transient myotonia persist long after overt motor symptoms have resolved, suggesting that a transient episode of muscle hyperexcitability is sufficient to trigger prolonged alterations in nociceptive processing. Physiological recordings revealed altered excitability of dorsal root ganglion and superficial dorsal horn neurons and enhanced sensory-evoked activity in the parabrachial nucleus, indicating altered nociceptive processing across multiple levels of the pain neuraxis. Transient myotonia increased total sodium current density in sensory neurons, with a shift toward a greater tetrodotoxin-resistant current fraction. Pharmacological inhibition with the NaV1.8-directed analgesic Suzetrigine markedly attenuated pain-like behaviors in both models of myotonia. Together, these findings establish a link between myotonia and persistent alterations in nociceptive processing and identify NaV1.8-directed analgesia as a promising therapeutic strategy for myotonia-associated pain.
Authors
Tyler S. Nelson, Aida Calderon-Rivera, Heather N. Allen, Alaina L Waters, Emanuel Loeza-Alcocer, Jorge B. Pineda-Farias, Narges Pachenari, Santiago Loya-Lopez, Kimberly Gomez, Erick J. Rodriguez-Palma, Paz Duran, Michael S. Gold, Rajesh Khanna
Abstract
Authors
Helena Reyes-Gopar, Matthew L. Bendall, Rodrigo R.R. Duarte, Timothy R. Powell, Douglas F. Nixon
Abstract
The neutrophil-to-lymphocyte ratio (NLR) is associated with unfavorable prognosis and hemorrhagic transformation (HT) in patients with ischemic stroke, yet the underlying mechanisms remain unclear. Using patient samples and a murine stroke model, we identified CD8⁺ regulatory T cells (CD8 Tregs) key regulators of neutrophil homeostasis after ischemic stroke, thereby limiting endothelial disruption and HT. Loss of CD8 Tregs expanded circulating neutrophils by extending their lifespan rather than altering proliferation, bone marrow release, or direct cytotoxicity. Mechanistically, CD8 Tregs shortened neutrophil lifespan by modulating HIF-1α–dependent glycolytic activity and relieving PD-L1–mediated suppression of bone marrow clearance. Finally, co-culture experiments with human CD8 Tregs and neutrophils revealed similar neutrophil-regulatory effects, accompanied by improved endothelial barrier integrity. These findings reveal a previously unrecognized CD8 Treg–neutrophil axis and suggest potential therapeutic strategies for preventing HT after stroke.
Authors
Jianan Lu, Qia Zhang, Jiarui Chen, Huaming Li, An Ping, Ziyang Jin, Xiaotao Zhang, Yichen Gu, Xuejiao Dai, Zihong Chen, Yajun Qian, Guoqiang Zhang, Jun Yu, Jianmin Zhang, Ligen Shi
Abstract
Mutations in the survival of motor neuron 1 (SMN1) can reduce functional SMN protein levels, which causes Spinal Muscular Atrophy (SMA), a disease affecting the nervous system and peripheral tissues, including the immune system. Yet, SMN expression across immune cell subsets and the impact of SMN-modulating therapies on the immune system remains underexplored. We found that in neonatal mouse spleen, SMN expression was highest in B cells, which were massively reduced in SMA mice. In human PBMCs from adults, DCs and monocytes expressed the highest SMN levels, whereas SMA patients showed reduced DC and increased B cell frequencies. Patients receiving systemic versus CNS-restricted therapy showed similar differences in immune cell composition and SMN levels. Similarly, an exploratory cohort including untreated patients did not indicate a substantial treatment-specific effect relative to controls. To assess the impact of differentiation on SMN, PMA-treated THP-1 cells were analyzed, revealing enhanced aberrant SMN splicing and increased SMN-positive Cajal bodies. In conclusion, SMN levels vary across immune cell types, and reduced SMN levels are associated with altered immune cell composition. Immune alterations and decreased SMN levels were observed in both treated and untreated SMA patients and may contribute to dysfunctions of the immune system in SMA.
Authors
Ines Tapken, Katharina Rahmel-Stein, Christine Ehlers, Federica Cieri, Nora T. Detering, Tobias Schüning, Bogdan Bjelica, Charlotte Mindermann, Svenja Neuhoff, Linda-Isabell Schmitt, Markus Leo, Tim Hagenacker, Sabine Illsinger, Elia Di Schiavi, Theresa Graalmann, Susanne Petri, Ulrich Kalinke, Peter Claus
Abstract
Authors
Seyi E. Elasoru, Christian Miccile, Jingwu Pan, Zhaoyang Zhang, Kalyanam Shivkumar, Herbert Herzog, Robert D. Harvey, Zhilin Qu, Olujimi A. Ajijola
Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)