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Simon CM, Delestree N, Montes J, Gerstner F, Carranza E, Sowoidnich L, Buettner JM, Pagiazitis JG, Prat-Ortega G, Ensel S, Donadio S, Garcia JL, Kratimenos P, Chung WK, Sumner CJ, Weimer LH, Pirondini E, Capogrosso M, Pellizzoni L, De Vivo DC, Mentis GZ. Dysfunction of proprioceptive sensory synapses is a pathogenic event and therapeutic target in mice and humans with spinal muscular atrophy. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.06.03.24308132. [PMID: 38883729 PMCID: PMC11177917 DOI: 10.1101/2024.06.03.24308132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Spinal muscular atrophy (SMA) is a neurodegenerative disease characterized by a varying degree of severity that correlates with the reduction of SMN protein levels. Motor neuron degeneration and skeletal muscle atrophy are hallmarks of SMA, but it is unknown whether other mechanisms contribute to the spectrum of clinical phenotypes. Here, through a combination of physiological and morphological studies in mouse models and SMA patients, we identify dysfunction and loss of proprioceptive sensory synapses as key signatures of SMA pathology. We demonstrate that SMA patients exhibit impaired proprioception, and their proprioceptive sensory synapses are dysfunctional as measured by the neurophysiological test of the Hoffmann reflex (H-reflex). We further show that loss of excitatory afferent synapses and altered potassium channel expression in SMA motor neurons are conserved pathogenic events found in both severely affected patients and mouse models. Lastly, we report that improved motor function and fatigability in ambulatory SMA patients and mouse models treated with SMN-inducing drugs correlate with increased function of sensory-motor circuits that can be accurately captured by the H-reflex assay. Thus, sensory synaptic dysfunction is a clinically relevant event in SMA, and the H-reflex is a suitable assay to monitor disease progression and treatment efficacy of motor circuit pathology.
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Affiliation(s)
- CM Simon
- Center for Motor Neuron Biology and Disease, Columbia University, NY, USA
- Dept. of Neurology, Columbia University, NY, USA
- Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - N Delestree
- Center for Motor Neuron Biology and Disease, Columbia University, NY, USA
- Dept. of Neurology, Columbia University, NY, USA
| | - J Montes
- Center for Motor Neuron Biology and Disease, Columbia University, NY, USA
- Dept. of Rehabilitation and Regenerative Medicine, Columbia University, NY, USA
| | - F Gerstner
- Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - E Carranza
- Depts. Physical Medicine & Rehabilitation & Bioengineering, University of Pittsburgh, PA, USA
- Rehab and Neural Engineering Labs, University of Pittsburgh, PA, USA
| | - L Sowoidnich
- Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - JM Buettner
- Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - JG Pagiazitis
- Center for Motor Neuron Biology and Disease, Columbia University, NY, USA
- Dept. of Neurology, Columbia University, NY, USA
| | - G Prat-Ortega
- Rehab and Neural Engineering Labs, University of Pittsburgh, PA, USA
- Depts. of Neurological Surgery & Bioengineering, University of Pittsburgh, PA, USA
| | - S Ensel
- Rehab and Neural Engineering Labs, University of Pittsburgh, PA, USA
- Depts. of Neurological Surgery & Bioengineering, University of Pittsburgh, PA, USA
| | - S Donadio
- Rehab and Neural Engineering Labs, University of Pittsburgh, PA, USA
- Depts. of Neurological Surgery & Bioengineering, University of Pittsburgh, PA, USA
| | - JL Garcia
- Dept. of Neurology, Columbia University, NY, USA
| | - P Kratimenos
- Center for Neuroscience Research, Children’s National Res. Institute, Washington, DC, USA
- Dept. of Pediatrics, G Washington Univ. Sch. of Medicine, Washington, DC, USA
| | - WK Chung
- Dept. of Pediatrics, Boston Children’s Hospital and Harvard Medical School, Boston, MA USA
| | - CJ Sumner
- Depts. of Neurology, Neuroscience and Genetic Medicine, Johns Hopkins University School of Medicine, MD, USA
| | - LH Weimer
- Dept. of Neurology, Columbia University, NY, USA
| | - E Pirondini
- Depts. Physical Medicine & Rehabilitation & Bioengineering, University of Pittsburgh, PA, USA
- Rehab and Neural Engineering Labs, University of Pittsburgh, PA, USA
| | - M Capogrosso
- Rehab and Neural Engineering Labs, University of Pittsburgh, PA, USA
- Depts. of Neurological Surgery & Bioengineering, University of Pittsburgh, PA, USA
| | - L Pellizzoni
- Center for Motor Neuron Biology and Disease, Columbia University, NY, USA
- Dept. of Neurology, Columbia University, NY, USA
- Dept. of Pathology and Cell Biology, Columbia University, NY, USA
| | - DC De Vivo
- Center for Motor Neuron Biology and Disease, Columbia University, NY, USA
- Dept. of Neurology, Columbia University, NY, USA
| | - GZ Mentis
- Center for Motor Neuron Biology and Disease, Columbia University, NY, USA
- Dept. of Neurology, Columbia University, NY, USA
- Dept. of Pathology and Cell Biology, Columbia University, NY, USA
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Nascimento F, Özyurt MG, Halablab K, Bhumbra GS, Caron G, Bączyk M, Zytnicki D, Manuel M, Roselli F, Brownstone R, Beato M. Spinal microcircuits go through multiphasic homeostatic compensations in a mouse model of motoneuron degeneration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.10.588918. [PMID: 38645210 PMCID: PMC11030447 DOI: 10.1101/2024.04.10.588918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
In neurological conditions affecting the brain, early-stage neural circuit adaption is key for long-term preservation of normal behaviour. We tested if motoneurons and respective microcircuits also adapt in the initial stages of disease progression in a mouse model of progressive motoneuron degeneration. Using a combination of in vitro and in vivo electrophysiology and super-resolution microscopy, we found that, preceding muscle denervation and motoneuron death, recurrent inhibition mediated by Renshaw cells is reduced in half due to impaired quantal size associated with decreased glycine receptor density. Additionally, higher probability of release from proprioceptive Ia terminals leads to increased monosynaptic excitation to motoneurons. Surprisingly, the initial impairment in recurrent inhibition is not a widespread feature of inhibitory spinal circuits, such as group I inhibitory afferents, and is compensated at later stages of disease progression. We reveal that in disease conditions, spinal microcircuits undergo specific multiphasic homeostatic compensations to preserve force output.
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Affiliation(s)
- Filipe Nascimento
- Department of Neuroscience Physiology and Pharmacology (NPP), Gower Street, University College London, WC1E 6BT, UK
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - M. Görkem Özyurt
- Department of Neuroscience Physiology and Pharmacology (NPP), Gower Street, University College London, WC1E 6BT, UK
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Kareen Halablab
- Department of Neurology, Ulm University, Ulm, Germany
- German Centre for Neurodegenerative Diseases-Ulm (DZNE-Ulm), Ulm, Germany
| | - Gardave Singh Bhumbra
- Department of Neuroscience Physiology and Pharmacology (NPP), Gower Street, University College London, WC1E 6BT, UK
| | - Guillaume Caron
- Saints-Pères Paris Institute for the Neurosciences (SPPIN), Université Paris Cité, Centre National de la Recherche Scientifique (CNRS), Paris, France
| | - Marcin Bączyk
- Department of Neurobiology, Poznań University of Physical Education, Poznań, Poland
| | - Daniel Zytnicki
- Saints-Pères Paris Institute for the Neurosciences (SPPIN), Université Paris Cité, Centre National de la Recherche Scientifique (CNRS), Paris, France
| | - Marin Manuel
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, USA
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
| | - Francesco Roselli
- Department of Neurology, Ulm University, Ulm, Germany
- German Centre for Neurodegenerative Diseases-Ulm (DZNE-Ulm), Ulm, Germany
| | - Rob Brownstone
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Marco Beato
- Department of Neuroscience Physiology and Pharmacology (NPP), Gower Street, University College London, WC1E 6BT, UK
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Harris-Warrick RM, Pecchi E, Drouillas B, Brocard F, Bos R. Effect of size on expression of bistability in mouse spinal motoneurons. J Neurophysiol 2024; 131:577-588. [PMID: 38380829 DOI: 10.1152/jn.00320.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 02/05/2024] [Accepted: 02/20/2024] [Indexed: 02/22/2024] Open
Abstract
Bistability in spinal motoneurons supports tonic spike activity in the absence of excitatory drive. Earlier work in adult preparations suggested that smaller motoneurons innervating slow antigravity muscle fibers are more likely to generate bistability for postural maintenance. However, whether large motoneurons innervating fast-fatigable muscle fibers display bistability is still controversial. To address this, we examined the relationship between soma size and bistability in lumbar (L4-L5) ventrolateral α-motoneurons of choline acetyltransferase (ChAT)-green fluorescent protein (GFP) and Hb9-GFP mice during the first 4 wk of life. We found that as neuron size increases, the prevalence of bistability rises. Smaller α-motoneurons lack bistability, whereas larger fast α-motoneurons [matrix metalloproteinase-9 (MMP-9)+/Hb9+] with a soma area ≥ 400 µm2 exhibit significantly higher bistability. Ionic currents associated with bistability, including the persistent Nav1.6 current, the thermosensitive Trpm5 Ca2+-activated Na+ current, and the slowly inactivating Kv1.2 current, also scale with cell size. Serotonin evokes full bistability in large motoneurons with partial bistable properties but not in small motoneurons. Our study provides important insights into the neural mechanisms underlying bistability and how motoneuron size correlates with bistability in mice.NEW & NOTEWORTHY Bistability is not a common feature of all mouse spinal motoneurons. It is absent in small, slow motoneurons but present in most large, fast motoneurons. This difference results from differential expression of ionic currents that enable bistability, which are highly expressed in large motoneurons but small or absent in small motoneurons. These results support a possible role for fast motoneurons in maintenance of tonic posture in addition to their known roles in fast movements.
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Affiliation(s)
- Ronald M Harris-Warrick
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, United States
| | - Emilie Pecchi
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
| | - Benoît Drouillas
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
| | - Frédéric Brocard
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
| | - Rémi Bos
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
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Özyurt MG, Nascimento F, Brownstone RM, Beato M. On the origin of F-wave: involvement of central synaptic mechanisms. Brain 2024; 147:406-413. [PMID: 37796028 PMCID: PMC10834253 DOI: 10.1093/brain/awad342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 09/21/2023] [Accepted: 09/27/2023] [Indexed: 10/06/2023] Open
Abstract
Neurophysiological methods are used widely to gain information about motor neuron excitability and axon conduction in neurodegenerative diseases. The F-wave is a common biomarker used to test motor neuron properties in the diagnosis of neurological diseases. Although the origin of the F-wave is a subject of debate, the most widely accepted mechanism posits that the F-wave is generated by the backfiring of motor neurons stimulated antidromically from the periphery. In this study, we developed an ex vivo mouse sciatic nerve-attached spinal cord preparation with sensory axons severed. In this preparation, stimulation of the whole sciatic nerve or its tibial branch evoked responses with the electrophysiological signatures of F-waves. Manipulations of synaptic transmission by either removal of extracellular calcium or block of post-synaptic glutamate receptors abolished these responses. These results suggest that F-waves are mediated by spinal microcircuits activated by recurrent motor axon collaterals via glutamatergic synapses.
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Affiliation(s)
- M Görkem Özyurt
- Department of Neuroscience Physiology and Pharmacology (NPP), University College London, London WC1E 6BT, UK
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Filipe Nascimento
- Department of Neuroscience Physiology and Pharmacology (NPP), University College London, London WC1E 6BT, UK
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Robert M Brownstone
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Marco Beato
- Department of Neuroscience Physiology and Pharmacology (NPP), University College London, London WC1E 6BT, UK
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Pocratsky AM, Nascimento F, Özyurt MG, White IJ, Sullivan R, O’Callaghan BJ, Smith CC, Surana S, Beato M, Brownstone RM. Pathophysiology of Dyt1- Tor1a dystonia in mice is mediated by spinal neural circuit dysfunction. Sci Transl Med 2023; 15:eadg3904. [PMID: 37134150 PMCID: PMC7614689 DOI: 10.1126/scitranslmed.adg3904] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 04/14/2023] [Indexed: 05/05/2023]
Abstract
Dystonia, a neurological disorder defined by abnormal postures and disorganized movements, is considered to be a neural circuit disorder with dysfunction arising within and between multiple brain regions. Given that spinal neural circuits constitute the final pathway for motor control, we sought to determine their contribution to this movement disorder. Focusing on the most common inherited form of dystonia in humans, DYT1-TOR1A, we generated a conditional knockout of the torsin family 1 member A (Tor1a) gene in the mouse spinal cord and dorsal root ganglia (DRG). We found that these mice recapitulated the phenotype of the human condition, developing early-onset generalized torsional dystonia. Motor signs emerged early in the mouse hindlimbs before spreading caudo-rostrally to affect the pelvis, trunk, and forelimbs throughout postnatal maturation. Physiologically, these mice bore the hallmark features of dystonia, including spontaneous contractions at rest and excessive and disorganized contractions, including cocontractions of antagonist muscle groups, during voluntary movements. Spontaneous activity, disorganized motor output, and impaired monosynaptic reflexes, all signs of human dystonia, were recorded from isolated mouse spinal cords from these conditional knockout mice. All components of the monosynaptic reflex arc were affected, including motor neurons. Given that confining the Tor1a conditional knockout to DRG did not lead to early-onset dystonia, we conclude that the pathophysiological substrate of this mouse model of dystonia lies in spinal neural circuits. Together, these data provide new insights into our current understanding of dystonia pathophysiology.
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Affiliation(s)
- Amanda M. Pocratsky
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
| | - Filipe Nascimento
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
| | - M. Görkem Özyurt
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
| | - Ian J. White
- Laboratory for Molecular Cell Biology, University College London; London, WC1E 6BT, UK
| | - Roisin Sullivan
- Department of Molecular Neuroscience, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
| | - Benjamin J. O’Callaghan
- Department of Molecular Neuroscience, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
| | - Calvin C. Smith
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
| | - Sunaina Surana
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
- UK Dementia Research Institute, University College London; London, WC1E 6BT, UK
| | - Marco Beato
- Department of Neuroscience, Physiology, and Pharmacology, University College London; London, WC1E 6BT, UK
| | - Robert M. Brownstone
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
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