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Lemon R. The Corticospinal System and Amyotrophic Lateral Sclerosis: IFCN handbook chapter. Clin Neurophysiol 2024; 160:56-67. [PMID: 38401191 DOI: 10.1016/j.clinph.2024.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 12/23/2023] [Accepted: 02/03/2024] [Indexed: 02/26/2024]
Abstract
Corticospinal neurons located in motor areas of the cerebral neocortex project corticospinal axons which synapse with the spinal network; a parallel corticobulbar system projects to the cranial motor network and to brainstem motor pathways. The primate corticospinal system has a widespread cortical origin and an extensive range of different fibre diameters, including thick, fast-conducting axons. Direct cortico-motoneuronal (CM) projections from the motor cortex to arm and hand alpha motoneurons are a recent evolutionary feature, that is well developed in dexterous primates and particularly in humans. Many of these projections originate from the caudal subdivision of area 4 ('new' M1: primary motor cortex). They arise from corticospinal neurons of varied soma size, including those with fast- and relatively slow-conducting axons. This CM system has been shown to be involved in the control of skilled movements, carried out with fractionation of the distal extremities and at low force levels. During movement, corticospinal neurons are activated quite differently from 'lower' motoneurons, and there is no simple or fixed functional relationship between a so-called 'upper' motoneuron and its target lower motoneuron. There are key differences in the organisation and function of the corticospinal and CM system in primates versus non-primates, such as rodents. These differences need to be recognized when making the choice of animal model for understanding disorders such as amyotrophic lateral sclerosis (ALS). In this neurodegenerative brain disease there is a selective loss of fast-conducting corticospinal axons, and their synaptic connections, and this is reflected in responses to non-invasive cortical stimuli and measures of cortico-muscular coherence. The loss of CM connections influencing distal limb muscles results in a differential loss of muscle strength or 'split-hand' phenotype. Importantly, there is also a unique impairment in the coordination of skilled hand tasks that require fractionation of digit movement. Scores on validated tests of skilled hand function could be used to assess disease progression.
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Affiliation(s)
- Roger Lemon
- Department of Clinical and Movement Sciences, Queen Square Institute of Neurology, UCL, London WC1N 3BG, UK.
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2
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Nolan M, Scott C, Hof PR, Ansorge O. Betz cells of the primary motor cortex. J Comp Neurol 2024; 532:e25567. [PMID: 38289193 PMCID: PMC10952528 DOI: 10.1002/cne.25567] [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: 08/09/2023] [Revised: 11/11/2023] [Accepted: 11/17/2023] [Indexed: 02/01/2024]
Abstract
Betz cells, named in honor of Volodymyr Betz (1834-1894), who described them as "giant pyramids" in the primary motor cortex of primates and other mammalian species, are layer V extratelencephalic projection (ETP) neurons that directly innervate α-motoneurons of the brainstem and spinal cord. Despite their large volume and circumferential dendritic architecture, to date, no single molecular criterion has been established that unequivocally distinguishes adult Betz cells from other layer V ETP neurons. In primates, transcriptional signatures suggest the presence of at least two ETP neuron clusters that contain mature Betz cells; these are characterized by an abundance of axon guidance and oxidative phosphorylation transcripts. How neurodevelopmental programs drive the distinct positional and morphological features of Betz cells in humans remains unknown. Betz cells display a distinct biphasic firing pattern involving early cessation of firing followed by delayed sustained acceleration in spike frequency and magnitude. Few cell type-specific transcripts and electrophysiological characteristics are conserved between rodent layer V ETP neurons of the motor cortex and primate Betz cells. This has implications for the modeling of disorders that affect the motor cortex in humans, such as amyotrophic lateral sclerosis (ALS). Perhaps vulnerability to ALS is linked to the evolution of neural networks for fine motor control reflected in the distinct morphomolecular architecture of the human motor cortex, including Betz cells. Here, we discuss histological, molecular, and functional data concerning the position of Betz cells in the emerging taxonomy of neurons across diverse species and their role in neurological disorders.
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Affiliation(s)
- Matthew Nolan
- Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
- Department of NeurologyMassachusetts General HospitalBostonMassachusettsUSA
| | - Connor Scott
- Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
| | - Patrick. R. Hof
- Nash Family Department of Neuroscience and Friedman Brain InstituteIcahn School of Medicine at Mount SinaiNew YorkNew YorkUSA
| | - Olaf Ansorge
- Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
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3
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Braaß H, Feldheim J, Chu Y, Tinnermann A, Finsterbusch J, Büchel C, Schulz R, Gerloff C. Association between activity in the ventral premotor cortex and spinal cord activation during force generation-A combined cortico-spinal fMRI study. Hum Brain Mapp 2023; 44:6471-6483. [PMID: 37873743 PMCID: PMC10681651 DOI: 10.1002/hbm.26523] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 10/04/2023] [Accepted: 10/08/2023] [Indexed: 10/25/2023] Open
Abstract
Force generation is a crucial element of dexterity and a highly relevant skill of the human motor system. How cerebral and spinal components interact and how spinal activation is associated with the activity in the cerebral primary motor and premotor areas is poorly understood. Here, we conducted combined cortico-spinal functional magnetic resonance imaging during a simple visually guided isometric force generation task in 20 healthy young subjects. Activation was localized in the right cervical spinal cord and left primary motor and premotor areas. The main finding is that spinal activation was negatively correlated with ventral premotor cortex activation. Spinal activation was furthermore significantly correlated with primary motor cortex activation, while increasing target forces led to an increase in the amount of activation. These data indicate that human premotor areas such as the ventral premotor cortex might be functionally connected to the lower cervical spinal cord contributing to distal upper limb functions, a finding that extends our understanding of human motor function beyond the animal literature.
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Affiliation(s)
- Hanna Braaß
- Department of NeurologyUniversity Medical Center Hamburg‐EppendorfHamburgGermany
| | - Jan Feldheim
- Department of NeurologyUniversity Medical Center Hamburg‐EppendorfHamburgGermany
| | - Ying Chu
- Institute of Systems NeuroscienceUniversity Medical Center Hamburg‐EppendorfHamburgGermany
| | - Alexandra Tinnermann
- Institute of Systems NeuroscienceUniversity Medical Center Hamburg‐EppendorfHamburgGermany
| | - Jürgen Finsterbusch
- Institute of Systems NeuroscienceUniversity Medical Center Hamburg‐EppendorfHamburgGermany
| | - Christian Büchel
- Institute of Systems NeuroscienceUniversity Medical Center Hamburg‐EppendorfHamburgGermany
| | - Robert Schulz
- Department of NeurologyUniversity Medical Center Hamburg‐EppendorfHamburgGermany
| | - Christian Gerloff
- Department of NeurologyUniversity Medical Center Hamburg‐EppendorfHamburgGermany
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4
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Genç B, Nho B, Seung H, Helmold B, Park H, Gözütok Ö, Kim S, Park J, Ye S, Lee H, Lee N, Yu SS, Kim S, Lee J, Özdinler H. Novel rAAV vector mediated intrathecal HGF delivery has an impact on neuroimmune modulation in the ALS motor cortex with TDP-43 pathology. Gene Ther 2023; 30:560-574. [PMID: 36823441 DOI: 10.1038/s41434-023-00383-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 12/21/2022] [Accepted: 01/23/2023] [Indexed: 02/25/2023]
Abstract
Recombinant adeno-associated virus (rAAV)-based gene therapies offer an immense opportunity for rare diseases, such as amyotrophic lateral sclerosis (ALS), which is defined by the loss of the upper and the lower motor neurons. Here, we describe generation, characterization, and utilization of a novel vector system, which enables expression of the active form of hepatocyte growth factor (HGF) under EF-1α promoter with bovine growth hormone (bGH) poly(A) sequence and is effective with intrathecal injections. HGF's role in promoting motor neuron survival had been vastly reported. Therefore, we investigated whether intrathecal delivery of HGF would have an impact on one of the most common pathologies of ALS: the TDP-43 pathology. Increased astrogliosis, microgliosis and progressive upper motor neuron loss are important consequences of ALS in the motor cortex with TDP-43 pathology. We find that cortex can be modulated via intrathecal injection, and that expression of HGF reduces astrogliosis, microgliosis in the motor cortex, and help restore ongoing UMN degeneration. Our findings not only introduce a novel viral vector for the treatment of ALS, but also demonstrate modulation of motor cortex by intrathecal viral delivery, and that HGF treatment is effective in reducing astrogliosis and microgliosis in the motor cortex of ALS with TDP-43 pathology.
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Affiliation(s)
- Barış Genç
- Department of Neurology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave, Chicago, IL, 60611, USA
| | - Boram Nho
- School of Biological Sciences, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea
- Helixmith Co., Ltd., R&D Center, 21, Magokjungang 8-ro 7-gil, Gangseo-gu, Seoul, 07794, Republic of Korea
| | - Hana Seung
- Helixmith Co., Ltd., R&D Center, 21, Magokjungang 8-ro 7-gil, Gangseo-gu, Seoul, 07794, Republic of Korea
| | - Benjamin Helmold
- Department of Neurology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave, Chicago, IL, 60611, USA
| | - Huiwon Park
- Helixmith Co., Ltd., R&D Center, 21, Magokjungang 8-ro 7-gil, Gangseo-gu, Seoul, 07794, Republic of Korea
| | - Öge Gözütok
- Department of Neurology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave, Chicago, IL, 60611, USA
| | - Seunghyun Kim
- Helixmith Co., Ltd., R&D Center, 21, Magokjungang 8-ro 7-gil, Gangseo-gu, Seoul, 07794, Republic of Korea
| | - Jinil Park
- Helixmith Co., Ltd., R&D Center, 21, Magokjungang 8-ro 7-gil, Gangseo-gu, Seoul, 07794, Republic of Korea
| | - Sanghyun Ye
- Helixmith Co., Ltd., R&D Center, 21, Magokjungang 8-ro 7-gil, Gangseo-gu, Seoul, 07794, Republic of Korea
| | - Haneul Lee
- Helixmith Co., Ltd., R&D Center, 21, Magokjungang 8-ro 7-gil, Gangseo-gu, Seoul, 07794, Republic of Korea
| | - Nayeon Lee
- School of Biological Sciences, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea
| | - Seung-Shin Yu
- Helixmith Co., Ltd., R&D Center, 21, Magokjungang 8-ro 7-gil, Gangseo-gu, Seoul, 07794, Republic of Korea
| | - Sunyoung Kim
- School of Biological Sciences, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea
- Helixmith Co., Ltd., R&D Center, 21, Magokjungang 8-ro 7-gil, Gangseo-gu, Seoul, 07794, Republic of Korea
| | - Junghun Lee
- School of Biological Sciences, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.
- Helixmith Co., Ltd., R&D Center, 21, Magokjungang 8-ro 7-gil, Gangseo-gu, Seoul, 07794, Republic of Korea.
| | - Hande Özdinler
- Department of Neurology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave, Chicago, IL, 60611, USA.
- Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Center for Developmental Therapeutics, Northwestern University, Evanston, IL, 60208, USA.
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Reale LA, Dyer MS, Perry SE, Young KM, Dickson TC, Woodhouse A, Blizzard CA. Pathologically mislocalised TDP-43 in upper motor neurons causes a die-forward spread of ALS-like pathogenic changes throughout the mouse corticomotor system. Prog Neurobiol 2023; 226:102449. [PMID: 37011806 DOI: 10.1016/j.pneurobio.2023.102449] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 02/02/2023] [Accepted: 03/24/2023] [Indexed: 04/03/2023]
Abstract
Alterations in upper motor neuron excitability are one of the earliest phenomena clinically detected in ALS, and in 97% of cases, the RNA/DNA binding protein, TDP-43, is mislocalised in upper and lower motor neurons. While these are two major pathological hallmarks in disease, our understanding of where disease pathology begins, and how it spreads through the corticomotor system, is incomplete. This project used a model where mislocalised TDP-43 was expressed in the motor cortex, to determine if localised cortical pathology could result in widespread corticomotor system degeneration. Mislocalised TDP-43 caused layer V excitatory neurons in the motor cortex to become hyperexcitable after 20 days of expression. Following cortical hyperexcitability, a spread of pathogenic changes through the corticomotor system was observed. By 30 days expression, there was a significant decrease in lower motor neuron number in the lumbar spinal cord. However, cell loss occurred selectively, with a significant loss in lumbar regions 1-3, and not lumbar regions 4-6. This regional vulnerability was associated with alterations in pre-synaptic excitatory and inhibitory proteins. Excitatory inputs (VGluT2) were increased in all lumbar regions, while inhibitory inputs (GAD65/67) were increased in lumbar regions 4-6 only. This data indicates that mislocalised TDP-43 in upper motor neurons can cause lower motor neuron degeneration. Furthermore, cortical pathology increased excitatory inputs to the spinal cord, to which local circuitry compensated with an upregulation of inhibition. These findings reveal how TDP-43 mediated pathology may spread through corticofugal tracts in ALS and identify a potential pathway for therapeutic intervention.
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Gautam M, Genç B, Helmold B, Ahrens A, Kuka J, Makrecka-Kuka M, Günay A, Koçak N, Aguilar-Wickings IR, Keefe D, Zheng G, Swaminathan S, Redmon M, Zariwala HA, Özdinler PH. SBT-272 improves TDP-43 pathology in ALS upper motor neurons by modulating mitochondrial integrity, motility, and function. Neurobiol Dis 2023; 178:106022. [PMID: 36716828 DOI: 10.1016/j.nbd.2023.106022] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 01/09/2023] [Accepted: 01/25/2023] [Indexed: 01/28/2023] Open
Abstract
Mitochondrial defects are one of the common underlying causes of neuronal vulnerability in neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), and TDP-43 pathology is the most commonly observed proteinopathy. Disrupted inner mitochondrial membrane (IMM) reported in the upper motor neurons (UMNs) of ALS patients with TDP-43 pathology is recapitulated in the UMNs of well-characterized hTDP-43 mouse model of ALS. The construct validity, such as shared and common cellular pathology in mice and human, offers a unique opportunity to test treatment strategies that may translate to patients. SBT-272 is a well-tolerated brain-penetrant small molecule that stabilizes cardiolipin, a phospholipid found in IMM, thereby restoring mitochondrial structure and respiratory function. We investigated whether SBT-272 can improve IMM structure and health in UMNs diseased with TDP-43 pathology in our well-characterized UMN reporter line for ALS. We found that SBT-272 significantly improved mitochondrial structural integrity and restored mitochondrial motility and function. This led to improved health of diseased UMNs in vitro. In comparison to edaravone and AMX0035, SBT-272 appeared more effective in restoring health of diseased UMNs. Chronic treatment of SBT-272 for sixty days starting at an early symptomatic stage of the disease in vivo led to a significant reduction in astrogliosis, microgliosis, and TDP-43 pathology in the ALS motor cortex. Our results underscore the therapeutic potential of SBT-272, especially within the context of TDP-43 pathology and mitochondrial dysfunction.
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Affiliation(s)
- Mukesh Gautam
- Department of Neurology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - Barış Genç
- Department of Neurology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - Benjamin Helmold
- Department of Neurology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - Angela Ahrens
- Department of Neurology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - Janis Kuka
- Latvian Institute of Organic Synthesis (LIOS), Aizkraukles Street 21, LV-2006 Riga, Latvia
| | - Marina Makrecka-Kuka
- Latvian Institute of Organic Synthesis (LIOS), Aizkraukles Street 21, LV-2006 Riga, Latvia
| | - Aksu Günay
- Department of Neurology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - Nuran Koçak
- Department of Neurology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - Izaak R Aguilar-Wickings
- Department of Neurology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - Dennis Keefe
- Stealth BioTherapeutics, 140 Kendrick St Building C, Needham, MA 02494, USA
| | - Guozhu Zheng
- Stealth BioTherapeutics, 140 Kendrick St Building C, Needham, MA 02494, USA
| | - Suchitra Swaminathan
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, 420 E Superior St, Chicago, IL 60611, USA.; Robert H. Lurie Comprehensive Cancer Research Center, Feinberg School of Medicine, Northwestern University, 675 N St Clair Fl 21 Ste 100, Chicago, IL 60611, USA
| | - Martin Redmon
- Stealth BioTherapeutics, 140 Kendrick St Building C, Needham, MA 02494, USA
| | - Hatim A Zariwala
- Stealth BioTherapeutics, 140 Kendrick St Building C, Needham, MA 02494, USA
| | - P Hande Özdinler
- Department of Neurology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA; Robert H. Lurie Comprehensive Cancer Research Center, Feinberg School of Medicine, Northwestern University, 675 N St Clair Fl 21 Ste 100, Chicago, IL 60611, USA; Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Center for Developmental Therapeutics, Northwestern University, 2205 Tech Dr, Evanston, IL 60208, USA..
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7
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Rockland KS. A brief sketch across multiscale and comparative neuroanatomical features. Front Neuroanat 2023; 17:1108363. [PMID: 36861111 PMCID: PMC9968756 DOI: 10.3389/fnana.2023.1108363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Accepted: 01/10/2023] [Indexed: 02/16/2023] Open
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Shirota Y, Otsuka J, Toda T, Hamada M. Neurophysiological differentiation of upper motor neuron damage in neurodegenerative disorders. Clin Neurophysiol Pract 2022; 7:273-278. [PMID: 36263296 PMCID: PMC9574772 DOI: 10.1016/j.cnp.2022.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/31/2022] [Accepted: 09/11/2022] [Indexed: 12/04/2022] Open
Abstract
ALS and MSA presented with similar profiles of upper motor neuron signs. Central motor conduction time was more abnormal in ALS than in MSA. Different structures may be involved in ALS and MSA along the corticospinal tract.
Objective Using transcranial magnetic stimulation (TMS) to delineate upper motor neuron (UMN) signs of two neurodegenerative disorders: amyotrophic lateral sclerosis (ALS) and multiple system atrophy (MSA). Methods Medical records including clinical signs for UMN damage and TMS results were reviewed retrospectively. The UMN signs were classified into none, mild, and severe based on neurological examination of various reflexes. Then TMS-elicited motor evoked potentials (MEPs) were recorded from a hand and a leg muscle to calculate the central motor conduction time (CMCT), which represents fast, mono-synaptic conduction along the corticospinal tract. Relations between the UMN signs and CMCT were analysed for the two diseases. Results Prevalence and severity of the UMN signs for ALS and MSA were comparable for both upper and lower limbs. However, abnormality in CMCT was found more frequently in ALS: CMCT abnormalities were found in upper limbs for 44% in ALS patients but only for 7% in MSA patients; CMCT abnormalities in lower limbs were 55% in ALS and 20% in MSA. Some ALS patients showed abnormal CMCT in limbs without UMN signs, which was not true for most MSA patients. Conclusions The abnormalities of CMCT were different in ALS and MSA, even for those who clinically had similar UMN signs. Sometimes, CMCT can reveal UMN damage in the absence of clinical UMN signs. Differences presumably derive from selective degeneration of different fibres in the motor descending pathways. Longitudinal studies must be conducted to accumulate neuroimaging and pathological findings. Significance CMCT can be useful to differentiate ALS and MSA.
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Genç B, Jara JH, Sanchez SS, Lagrimas AKB, Gözütok Ö, Koçak N, Zhu Y, Hande Özdinler P. Upper motor neurons are a target for gene therapy and UCHL1 is necessary and sufficient to improve cellular integrity of diseased upper motor neurons. Gene Ther 2022; 29:178-192. [PMID: 34853443 PMCID: PMC9018479 DOI: 10.1038/s41434-021-00303-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 12/15/2022]
Abstract
There are no effective cures for upper motor neuron (UMN) diseases, such as amyotrophic lateral sclerosis (ALS), primary lateral sclerosis, and hereditary spastic paraplegia. Here, we show UMN loss occurs independent of spinal motor neuron degeneration and that UMNs are indeed effective cellular targets for gene therapy, which offers a potential solution especially for UMN disease patients. UCHL1 (ubiquitin C-terminal hydrolase-L1) is a deubiquitinating enzyme crucial for maintaining free ubiquitin levels. Corticospinal motor neurons (CSMN, a.k.a UMNs in mice) show early, selective, and profound degeneration in Uchl1nm3419 (UCHL1-/-) mice, which lack all UCHL1 function. When UCHL1 activity is ablated only from spinal motor neurons, CSMN remained intact. However, restoring UCHL1 specifically in CSMN of UCHL1-/- mice via directed gene delivery was sufficient to improve CSMN integrity to the healthy control levels. In addition, when UCHL1 gene was delivered selectively to CSMN that are diseased due to misfolded SOD1 toxicity and TDP-43 pathology via AAV-mediated retrograde transduction, the disease causing misfolded SOD1 and mutant human TDP-43 were reduced in hSOD1G93A and prpTDP-43A315T models, respectively. Diseased CSMN retained their neuronal integrity and cytoarchitectural stability in two different mouse models that represent two distinct causes of neurodegeneration in ALS.
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Affiliation(s)
- Barış Genç
- Davee Department of Neurology and Clinical Neurological Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Javier H Jara
- Davee Department of Neurology and Clinical Neurological Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Santana S Sanchez
- Davee Department of Neurology and Clinical Neurological Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Amiko K B Lagrimas
- Davee Department of Neurology and Clinical Neurological Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Öge Gözütok
- Davee Department of Neurology and Clinical Neurological Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Nuran Koçak
- Davee Department of Neurology and Clinical Neurological Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Yongling Zhu
- Departments of Ophthalmology and Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - P Hande Özdinler
- Davee Department of Neurology and Clinical Neurological Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL, 60611, USA.
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Eisen A, Bede P. The strength of corticomotoneuronal drive underlies ALS split phenotypes and reflects early upper motor neuron dysfunction. Brain Behav 2021; 11:e2403. [PMID: 34710283 PMCID: PMC8671797 DOI: 10.1002/brb3.2403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 09/02/2021] [Accepted: 10/05/2021] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Split phenotypes, (split hand, elbow, leg, and foot), are probably unique to ALS, and are characterized by having a shared peripheral input of both affected and unaffected muscles. This implies an anatomical origin rostral to the spinal cord, primarily within the cerebral cortex. Therefore, split phenotypes are a potential marker of ALS upper motor neuron pathology. However, to date, reports documenting upper motor neuron dysfunction in split phenotypes have been limited to using transcranial magnetic stimulation and cortical threshold tracking techniques. Here, we consider several other potential methodologies that could confirm a primary upper motor neuron pathology in split phenotypes. METHODS We review the potential of: 1. measuring the compound excitatory post-synaptic potential recorded from a single activated motor unit, 2. cortical-muscular coherence, and 3. new advanced modalities of neuroimaging (high-resolution imaging protocols, ultra-high field MRI platforms [7T], and novel Non-Gaussian diffusion models). CONCLUSIONS We propose that muscles involved in split phenotypes are those functionally involved in the human motor repertoire used particularly in complex activities. Their anterior horn cells receive the strongest corticomotoneuronal input. This is also true of the weakest muscles that are the earliest to be affected in ALS. Descriptions of split hand in non-ALS cases and proposals that peripheral nerve or muscle dysfunction may be causative are contentious. Only a few carefully controlled cases of each form of split phenotype, using upper motor neuron directed methodologies, are necessary to prove our postulate.
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Affiliation(s)
- Andrew Eisen
- Division of Neurology, Department of Medicine, University of British Columbia, British Columbia, Canada
| | - Peter Bede
- Computational Neuroimaging Group, Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland.,Pitié-Salpêtrière University Hospital, Sorbonne University, Paris, France
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11
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Fishman PS, Fischell JM. Focused Ultrasound Mediated Opening of the Blood-Brain Barrier for Neurodegenerative Diseases. Front Neurol 2021; 12:749047. [PMID: 34803886 PMCID: PMC8599441 DOI: 10.3389/fneur.2021.749047] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/27/2021] [Indexed: 01/31/2023] Open
Abstract
The blood brain barrier (BBB) is an obstacle for the delivery of potential molecular therapies for neurodegenerative diseases such as Parkinson's disease (PD), Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS). Although there has been a proliferation of potential disease modifying therapies for these progressive conditions, strategies to deliver these large agents remain limited. High intensity MRI guided focused ultrasound has already been FDA approved to lesion brain targets to treat movement disorders, while lower intensity pulsed ultrasound coupled with microbubbles commonly used as contrast agents can create transient safe opening of the BBB. Pre-clinical studies have successfully delivered growth factors, antibodies, genes, viral vectors, and nanoparticles in rodent models of AD and PD. Recent small clinical trials support the safety and feasibility of this strategy in these vulnerable patients. Further study is needed to establish safety as MRI guided BBB opening is used to enhance the delivery of newly developed molecular therapies.
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12
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Eisen A, Lemon R. The motor deficit of ALS reflects failure to generate muscle synergies for complex motor tasks, not just muscle strength. Neurosci Lett 2021; 762:136171. [PMID: 34391870 DOI: 10.1016/j.neulet.2021.136171] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/09/2021] [Accepted: 08/10/2021] [Indexed: 11/17/2022]
Abstract
Customarily the motor deficits that develop in ALS are considered in terms of muscle weakness. Functional rating scales used to assess ALS in terms of functional decline do not measure the deficits when performing complex motor tasks, that make up the human skilled motor repertoire, best exemplified by tasks requiring skilled hand and finger movement. This repertoire depends primarily upon the strength of direct corticomotoneuronal (CM) connectivity from primary motor cortex to the motor units subserving skilled movements. Our review prompts the question: if accumulating evidence suggests involvement of the CM system in the early stages of ALS, what kinds of motor deficit might be expected to result, and is current methodology able to identify such deficits? We point out that the CM system is organized not in "commands" to individual muscles, but rather encodes the building blocks of complex and intricate movements, which depend upon synergy between not only the prime mover muscles, but other muscles that stabilize the limb during skilled movement. Our knowledge of the functional organization of the CM system has come both from invasive studies in non-human primates and from advanced imaging and neurophysiological techniques in humans, some of which are now being applied in ALS. CM pathology in ALS has consequences not only for muscle strength, but importantly in the failure to generate complex motor tasks, often involving elaborate muscle synergies. Our aim is to encourage innovative methodology specifically directed to assessing complex motor tasks, failure of which is likely a very early clinical deficit in ALS.
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Affiliation(s)
- Andrew Eisen
- Division of Neurology, Department of Medicine, University of British Columbia, Vancouver, Canada.
| | - Roger Lemon
- Department of Clinical and Motor Neurosciences, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK.
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