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Chiu WH, Wattad N, Goldberg JA. Ion channel dysregulation and cellular adaptations to alpha-synuclein in stressful pacemakers of the parkinsonian brainstem. Pharmacol Ther 2024; 260:108683. [PMID: 38950869 DOI: 10.1016/j.pharmthera.2024.108683] [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: 01/23/2024] [Revised: 06/21/2024] [Accepted: 06/28/2024] [Indexed: 07/03/2024]
Abstract
Parkinson's disease (PD) is diagnosed by its cardinal motor symptoms that are associated with the loss of dopamine neurons in the substantia nigra pars compacta (SNc). However, PD patients suffer from various non-motor symptoms years before diagnosis. These prodromal symptoms are thought to be associated with the appearance of Lewy body pathologies (LBP) in brainstem regions such as the dorsal motor nucleus of the vagus (DMV), the locus coeruleus (LC) and others. The neurons in these regions that are vulnerable to LBP are all slow autonomous pacemaker neurons that exhibit elevated oxidative stress due to their perpetual influx of Ca2+ ions. Aggregation of toxic α-Synuclein (aSyn) - the main constituent of LBP - during the long prodromal period challenges these vulnerable neurons, presumably altering their biophysics and physiology. In contrast to pathophysiology of late stage parkinsonism which is well-documented, little is known about the pathophysiology of the brainstem during prodromal PD. In this review, we discuss ion channel dysregulation associated with aSyn aggregation in brainstem pacemaker neurons and their cellular responses to them. While toxic aSyn elevates oxidative stress in SNc and LC pacemaker neurons and exacerbates their phenotype, DMV neurons mount an adaptive response that mitigates the oxidative stress. Ion channel dysregulation and cellular adaptations may be the drivers of the prodromal symptoms of PD. For example, selective targeting of toxic aSyn to DMV pacemakers, elevates the surface density of K+ channels, which slows their firing rate, resulting in reduced parasympathetic tone to the gastrointestinal tract, which resembles the prodromal PD symptoms of dysphagia and constipation. The divergent responses of SNc & LC vs. DMV pacemaker neurons may explain why the latter outlive the former despite presenting LBPs earlier. Elucidation the brainstem pathophysiology of prodromal PD could pave the way for physiological biomarkers, earlier diagnosis and novel neuroprotective therapies for PD.
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Affiliation(s)
- Wei-Hua Chiu
- Department of Neurology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Nadine Wattad
- Department of Medical Neurobiology, Institute of Medical Research Israel - Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102 Jerusalem, Israel
| | - Joshua A Goldberg
- Department of Medical Neurobiology, Institute of Medical Research Israel - Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102 Jerusalem, Israel; Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.
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2
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de Souza JGV, de Souza DP, da Silva CAA, Martins Sá RW, Paton JFR, da Silva MP, Moraes DJA. Electrophysiological Properties and Morphology of Cardiac and Pulmonary Motoneurons within the Dorsal Motor Nucleus of the Vagus of Rats. Neuroscience 2024; 551:153-165. [PMID: 38821242 DOI: 10.1016/j.neuroscience.2024.05.038] [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: 02/16/2024] [Revised: 05/24/2024] [Accepted: 05/27/2024] [Indexed: 06/02/2024]
Abstract
The dorsal motor nucleus of the vagus (DMV) contains parasympathetic motoneurons that project to the heart and lungs. These motoneurons control ventricular excitability/contractility and airways secretions/blood flow, respectively. However, their electrophysiological properties, morphology and synaptic input activity remain unknown. One important ionic current described in DMV motoneurons controlling their electrophysiological behaviour is the A-type mediated by voltage-dependent K+ (Kv) channels. Thus, we compared the electrophysiological properties, synaptic activity, morphology, A-type current density, and single cell expression of Kv subunits, that contribute to macroscopic A-type currents, between DMV motoneurons projecting to either the heart or lungs of adult male rats. Using retrograde labelling, we visualized distinct DMV motoneurons projecting to the heart or lungs in acutely prepared medullary slices. Subsequently, whole cell recordings, morphological reconstruction and single motoneuron qRT-PCR studies were performed. DMV pulmonary motoneurons were more depolarized, electrically excitable, presented higher membrane resistance, broader action potentials and received greater excitatory synaptic inputs compared to cardiac DMV motoneurons. These differences were in part due to highly branched dendritic complexity and lower magnitude of A-type K+ currents. By evaluating expression of channels that mediate A-type currents from single motoneurons, we demonstrated a lower level of Kv4.2 in pulmonary versus cardiac motoneurons, whereas Kv4.3 and Kv1.4 levels were similar. Thus, with the distinct electrical, morphological, and molecular properties of DMV cardiac and pulmonary motoneurons, we surmise that these cells offer a new vista of opportunities for genetic manipulation providing improvement of parasympathetic function in cardiorespiratory diseases such heart failure and asthma.
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Affiliation(s)
- Júlia G V de Souza
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Daniel P de Souza
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Carlos A A da Silva
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Renato W Martins Sá
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Julian F R Paton
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Melina P da Silva
- Department of Biophysics, Paulista School of Medicine, Federal University of São Paulo, São Paulo, SP, Brazil.
| | - Davi J A Moraes
- Department of Physiology and Biophysics, Biomedical Science Institute, University of São Paulo, São Paulo, SP, Brazil.
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Kulkarni AS, Burns MR, Brundin P, Wesson DW. Linking α-synuclein-induced synaptopathy and neural network dysfunction in early Parkinson's disease. Brain Commun 2022; 4:fcac165. [PMID: 35822101 PMCID: PMC9272065 DOI: 10.1093/braincomms/fcac165] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 03/11/2022] [Accepted: 06/20/2022] [Indexed: 01/18/2023] Open
Abstract
The prodromal phase of Parkinson's disease is characterized by aggregation of the misfolded pathogenic protein α-synuclein in select neural centres, co-occurring with non-motor symptoms including sensory and cognitive loss, and emotional disturbances. It is unclear whether neuronal loss is significant during the prodrome. Underlying these symptoms are synaptic impairments and aberrant neural network activity. However, the relationships between synaptic defects and network-level perturbations are not established. In experimental models, pathological α-synuclein not only impacts neurotransmission at the synaptic level, but also leads to changes in brain network-level oscillatory dynamics-both of which likely contribute to non-motor deficits observed in Parkinson's disease. Here we draw upon research from both human subjects and experimental models to propose a 'synapse to network prodrome cascade' wherein before overt cell death, pathological α-synuclein induces synaptic loss and contributes to aberrant network activity, which then gives rise to prodromal symptomology. As the disease progresses, abnormal patterns of neural activity ultimately lead to neuronal loss and clinical progression of disease. Finally, we outline goals and research needed to unravel the basis of functional impairments in Parkinson's disease and other α-synucleinopathies.
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Affiliation(s)
- Aishwarya S Kulkarni
- Department of Pharmacology & Therapeutics, University of Florida, 1200 Newell Dr, Gainesville, FL 32610, USA
| | - Matthew R Burns
- Department of Neurology, University of Florida, 1200 Newell Dr, Gainesville, FL 32610, USA
- Norman Fixel Institute for Neurological Disorders, University of Florida, 1200 Newell Dr, Gainesville, FL 32610, USA
| | - Patrik Brundin
- Pharma Research and Early Development (pRED), F. Hoffman-La Roche, Little Falls, NJ, USA
| | - Daniel W Wesson
- Department of Pharmacology & Therapeutics, University of Florida, 1200 Newell Dr, Gainesville, FL 32610, USA
- Norman Fixel Institute for Neurological Disorders, University of Florida, 1200 Newell Dr, Gainesville, FL 32610, USA
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Na + leak-current channel (NALCN) at the junction of motor and neuropsychiatric symptoms in Parkinson's disease. J Neural Transm (Vienna) 2021; 128:749-762. [PMID: 33961117 DOI: 10.1007/s00702-021-02348-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 04/30/2021] [Indexed: 12/27/2022]
Abstract
Parkinson's disease (PD) is a debilitating movement disorder often accompanied by neuropsychiatric symptoms that stem from the loss of dopaminergic function in the basal ganglia and altered neurotransmission more generally. Akinesia, postural instability, tremors and frozen gait constitute the major motor disturbances, whereas neuropsychiatric symptoms include altered circadian rhythms, disordered sleep, depression, psychosis and cognitive impairment. Evidence is emerging that the motor and neuropsychiatric symptoms may share etiologic factors. Calcium/ion channels (CACNA1C, NALCN), synaptic proteins (SYNJ1) and neuronal RNA-binding proteins (RBFOX1) are among the risk genes that are common to PD and various psychiatric disorders. The Na+ leak-current channel (NALCN) is the focus of this review because it has been implicated in dystonia, regulation of movement, cognitive impairment, sleep and circadian rhythms. It regulates the resting membrane potential in neurons, mediates pace-making activity, participates in synaptic vesicle recycling and is functionally co-localized to the endoplasmic reticulum (ER)-several of the major processes adversely affected in PD. Here, we summarize the literature on mechanisms and pathways that connect the motor and neuropsychiatric symptoms of PD with a focus on recurring relationships to the NALCN. It is hoped that the various connections outlined here will stimulate further discussion, suggest additional areas for exploration and ultimately inspire novel treatment strategies.
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Chiu WH, Kovacheva L, Musgrove RE, Arien-Zakay H, Koprich JB, Brotchie JM, Yaka R, Ben-Zvi D, Hanani M, Roeper J, Goldberg JA. α-Synuclein-induced Kv4 channelopathy in mouse vagal motoneurons drives nonmotor parkinsonian symptoms. SCIENCE ADVANCES 2021; 7:eabd3994. [PMID: 33692101 PMCID: PMC7946367 DOI: 10.1126/sciadv.abd3994] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 01/25/2021] [Indexed: 05/06/2023]
Abstract
No disease-modifying therapy is currently available for Parkinson's disease (PD), the second most common neurodegenerative disease. The long nonmotor prodromal phase of PD is a window of opportunity for early detection and intervention. However, we lack the pathophysiological understanding to develop selective biomarkers and interventions. By using a mutant α-synuclein selective-overexpression mouse model of prodromal PD, we identified a cell-autonomous selective Kv4 channelopathy in dorsal motor nucleus of the vagus (DMV) neurons. This functional remodeling of intact DMV neurons leads to impaired pacemaker function in vitro and in vivo, which, in turn, reduces gastrointestinal motility, a common early symptom of prodromal PD. We identify a chain of events from α-synuclein via a biophysical dysfunction of a specific neuronal population to a clinically relevant prodromal symptom. These findings will facilitate the rational design of clinical biomarkers to identify people at risk for developing PD.
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Affiliation(s)
- Wei-Hua Chiu
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102 Jerusalem, Israel
| | - Lora Kovacheva
- Institute of Neurophysiology, Neuroscience Center, Goethe University, 60590 Frankfurt, Germany
| | - Ruth E Musgrove
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102 Jerusalem, Israel
| | - Hadar Arien-Zakay
- School of Pharmacy, Institute for Drug Research, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102 Jerusalem, Israel
| | - James B Koprich
- Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, ON M5T 2S8, Canada
- Atuka Inc., Toronto, ON M5X 1C9, Canada
| | - Jonathan M Brotchie
- Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, ON M5T 2S8, Canada
- Atuka Inc., Toronto, ON M5X 1C9, Canada
| | - Rami Yaka
- School of Pharmacy, Institute for Drug Research, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102 Jerusalem, Israel
| | - Danny Ben-Zvi
- Department of Developmental Biology and Cancer Research, Institute of Medical Research Israel-Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102 Jerusalem, Israel
| | - Menachem Hanani
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102 Jerusalem, Israel
- Laboratory of Experimental Surgery, Hadassah Medical Center, Mount Scopus, 91240 Jerusalem, Israel
| | - Jochen Roeper
- Institute of Neurophysiology, Neuroscience Center, Goethe University, 60590 Frankfurt, Germany
| | - Joshua A Goldberg
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102 Jerusalem, Israel.
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Input-output signal processing plasticity of vagal motor neurons in response to cardiac ischemic injury. iScience 2021; 24:102143. [PMID: 33665562 PMCID: PMC7898179 DOI: 10.1016/j.isci.2021.102143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 01/01/2021] [Accepted: 01/29/2021] [Indexed: 11/23/2022] Open
Abstract
Vagal stimulation is emerging as the next frontier in bioelectronic medicine to modulate peripheral organ health and treat disease. The neuronal molecular phenotypes in the dorsal motor nucleus of the vagus (DMV) remain largely unexplored, limiting the potential for harnessing the DMV plasticity for therapeutic interventions. We developed a mesoscale single-cell transcriptomics data from hundreds of DMV neurons under homeostasis and following physiological perturbations. Our results revealed that homeostatic DMV neuronal states can be organized into distinguishable input-output signal processing units. Remote ischemic preconditioning induced a distinctive shift in the neuronal states toward diminishing the role of inhibitory inputs, with concomitant changes in regulatory microRNAs miR-218a and miR-495. Chronic cardiac ischemic injury resulted in a dramatic shift in DMV neuronal states suggestive of enhanced neurosecretory function. We propose a DMV molecular network mechanism that integrates combinatorial neurotransmitter inputs from multiple brain regions and humoral signals to modulate cardiac health.
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Zampese E, Surmeier DJ. Calcium, Bioenergetics, and Parkinson's Disease. Cells 2020; 9:cells9092045. [PMID: 32911641 PMCID: PMC7564460 DOI: 10.3390/cells9092045] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/04/2020] [Accepted: 09/07/2020] [Indexed: 12/12/2022] Open
Abstract
Degeneration of substantia nigra (SN) dopaminergic (DAergic) neurons is responsible for the core motor deficits of Parkinson’s disease (PD). These neurons are autonomous pacemakers that have large cytosolic Ca2+ oscillations that have been linked to basal mitochondrial oxidant stress and turnover. This review explores the origin of Ca2+ oscillations and their role in the control of mitochondrial respiration, bioenergetics, and mitochondrial oxidant stress.
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Foo ASC, Soong TW, Yeo TT, Lim KL. Mitochondrial Dysfunction and Parkinson's Disease-Near-Infrared Photobiomodulation as a Potential Therapeutic Strategy. Front Aging Neurosci 2020; 12:89. [PMID: 32308618 PMCID: PMC7145956 DOI: 10.3389/fnagi.2020.00089] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/17/2020] [Indexed: 12/21/2022] Open
Abstract
As the main driver of energy production in eukaryotes, mitochondria are invariably implicated in disorders of cellular bioenergetics. Given that dopaminergic neurons affected in Parkinson's disease (PD) are particularly susceptible to energy fluctuations by their high basal energy demand, it is not surprising to note that mitochondrial dysfunction has emerged as a compelling candidate underlying PD. A recent approach towards forestalling dopaminergic neurodegeneration in PD involves near-infrared (NIR) photobiomodulation (PBM), which is thought to enhance mitochondrial function of stimulated cells through augmenting the activity of cytochrome C oxidase. Notwithstanding this, our understanding of the neuroprotective mechanism of PBM remains far from complete. For example, studies focusing on the effects of PBM on gene transcription are limited, and the mechanism through which PBM exerts its effects on distant sites (i.e., its "abscopal effect") remains unclear. Also, the clinical application of NIR in PD proves to be challenging. Efficacious delivery of NIR light to the substantia nigra pars compacta (SNpc), the primary site of disease pathology in PD, is fraught with technical challenges. Concerted efforts focused on understanding the biological effects of PBM and improving the efficiency of intracranial NIR delivery are therefore essential for its successful clinical translation. Nonetheless, PBM represents a potential novel therapy for PD. In this review, we provide an update on the role of mitochondrial dysfunction in PD and how PBM may help mitigate the neurodegenerative process. We also discussed clinical translation aspects of this treatment modality using intracranially implanted NIR delivery devices.
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Affiliation(s)
- Aaron Song Chuan Foo
- Department of Physiology, National University of Singapore, Singapore, Singapore
- Division of Neurosurgery, Department of Surgery, University Surgical Cluster, National University Hospital, Singapore, Singapore
| | - Tuck Wah Soong
- Department of Physiology, National University of Singapore, Singapore, Singapore
| | - Tseng Tsai Yeo
- Division of Neurosurgery, Department of Surgery, University Surgical Cluster, National University Hospital, Singapore, Singapore
| | - Kah-Leong Lim
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- Department of Research, National Neuroscience Institute, Singapore, Singapore
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Bove C, Coleman FH, Travagli RA. Characterization of the Basic Membrane Properties of Neurons of the Rat Dorsal Motor Nucleus of the Vagus in Paraquat-Induced Models of Parkinsonism. Neuroscience 2019; 418:122-132. [PMID: 31491501 PMCID: PMC6878173 DOI: 10.1016/j.neuroscience.2019.08.048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 08/28/2019] [Accepted: 08/29/2019] [Indexed: 02/07/2023]
Abstract
Most of Parkinson's disease (PD) patients experience gastrointestinal dysfunctions, including gastric hypomotility. The dorsal motor nucleus of the vagus (DMV) modulates the motility of the upper gastrointestinal (GI) tract. Paraquat (P) administration induces Parkinsonism in experimental models, and we have developed recently an environmental model of Parkinsonism in which rats are treated with subthreshold doses of P and lectins (P + L), in both models rats develop reduced gastric motility prodromal to the full extent of motor deficits. The aim of the present study was to examine whether the membrane properties of DMV neurons in these two experimental models of Parkinsonism were altered. Whole cell recordings in slices containing DMV neurons were conducted in male Sprague Dawley rats which received either injections of paraquat (10 mg/kg i.p.; 10P), or oral administration of paraquat (1 mg/kg) and lectin (0.05% w/v; P + L). Morphological reconstructions of DMV neurons were conducted at the end of the recordings. The repolarization kinetics of the afterhyperpolarization phase of the action potential was accelerated in 10P neurons vs control, while the phase plot revealed a slower depolarizing slope. At baseline, the amplitude of miniature excitatory postsynaptic currents was increased in P + L neurons. No differences in the morphology of DMV neurons were observed. These data indicate that the membrane and synaptic properties of DMV neurons are altered in rodent models of Parkinsonism, in which neurons of 10P and P + L rats demonstrate an increased excitatory transmission, perhaps in an attempt to counteract the paraquat-induced gastric hypomotility.
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Affiliation(s)
- C Bove
- Department of Neural and Behavioral Sciences, Penn State - College of Medicine, Hershey, PA, United States of America
| | - F H Coleman
- Department of Neural and Behavioral Sciences, Penn State - College of Medicine, Hershey, PA, United States of America
| | - R A Travagli
- Department of Neural and Behavioral Sciences, Penn State - College of Medicine, Hershey, PA, United States of America.
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Mutant α-Synuclein Overexpression Induces Stressless Pacemaking in Vagal Motoneurons at Risk in Parkinson's Disease. J Neurosci 2017; 37:47-57. [PMID: 28053029 DOI: 10.1523/jneurosci.1079-16.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 10/20/2016] [Accepted: 10/27/2016] [Indexed: 01/03/2023] Open
Abstract
α-Synuclein overexpression (ASOX) drives the formation of toxic aggregates in neurons vulnerable in Parkinson's disease (PD), including dopaminergic neurons of the substantia nigra (SN) and cholinergic neurons of the dorsal motor nucleus of the vagus (DMV). Just as these populations differ in when they exhibit α-synucleinopathies during PD pathogenesis, they could also differ in their physiological responses to ASOX. An ASOX-mediated hyperactivity of SN dopamine neurons, which was caused by oxidative dysfunction of Kv4.3 potassium channels, was recently identified in transgenic (A53T-SNCA) mice overexpressing mutated human α-synuclein. Noting that DMV neurons display extensive α-synucleinopathies earlier than SN dopamine neurons while exhibiting milder cell loss in PD, we aimed to define the electrophysiological properties of DMV neurons in A53T-SNCA mice. We found that DMV neurons maintain normal firing rates in response to ASOX. Moreover, Kv4.3 channels in DMV neurons exhibit no oxidative dysfunction in the A53T-SNCA mice, which could only be recapitulated in wild-type mice by glutathione dialysis. Two-photon imaging of redox-sensitive GFP corroborated the finding that mitochondrial oxidative stress was diminished in DMV neurons in the A53T-SNCA mice. This reduction in oxidative stress resulted from a transcriptional downregulation of voltage-activated (Cav) calcium channels in DMV neurons, which led to a reduction in activity-dependent calcium influx via Cav channels. Thus, ASOX induces a homeostatic remodeling with improved redox signaling in DMV neurons, which could explain the differential vulnerability of SN dopamine and DMV neurons in PD and could promote neuroprotective strategies that emulate endogenous homeostatic responses to ASOX (e.g., stressless pacemaking) in DMV neurons. SIGNIFICANCE STATEMENT Overexpression of mutant α-synuclein causes Parkinson's disease, presumably by driving neurodegeneration in vulnerable neuronal target populations. However, the extent of α-synuclein pathology (e.g., Lewy bodies) is not directly related to the degree of neurodegeneration across various vulnerable neuronal populations. Here, we show that, in contrast to dopamine neurons in the substantia nigra, vagal motoneurons do not enhance their excitability and oxidative load in response to chronic mutant α-synuclein overexpression. Rather, by downregulating their voltage-activated calcium channels, vagal motoneurons acquire a stressless form of pacemaking that diminishes mitochondrial and cytosolic oxidative stress. Emulating this endogenous adaptive response to α-synuclein overexpression could lead to novel strategies to protect dopamine neurons and perhaps delay the onset of Parkinson's disease.
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Vivas O, Moreno CM, Santana LF, Hille B. Proximal clustering between BK and Ca V1.3 channels promotes functional coupling and BK channel activation at low voltage. eLife 2017; 6. [PMID: 28665272 PMCID: PMC5503510 DOI: 10.7554/elife.28029] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 06/28/2017] [Indexed: 01/09/2023] Open
Abstract
CaV-channel dependent activation of BK channels is critical for feedback control of both calcium influx and cell excitability. Here we addressed the functional and spatial interaction between BK and CaV1.3 channels, unique CaV1 channels that activate at low voltages. We found that when BK and CaV1.3 channels were co-expressed in the same cell, BK channels started activating near −50 mV, ~30 mV more negative than for activation of co-expressed BK and high-voltage activated CaV2.2 channels. In addition, single-molecule localization microscopy revealed striking clusters of CaV1.3 channels surrounding clusters of BK channels and forming a multi-channel complex both in a heterologous system and in rat hippocampal and sympathetic neurons. We propose that this spatial arrangement allows tight tracking between local BK channel activation and the gating of CaV1.3 channels at quite negative membrane potentials, facilitating the regulation of neuronal excitability at voltages close to the threshold to fire action potentials. DOI:http://dx.doi.org/10.7554/eLife.28029.001
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Affiliation(s)
- Oscar Vivas
- Department of Physiology and Biophysics, University of Washington, Seattle, United States.,Department of Physiology and Membrane Biology, University of California, Davis, Davis, United States
| | - Claudia M Moreno
- Department of Physiology and Biophysics, University of Washington, Seattle, United States.,Department of Physiology and Membrane Biology, University of California, Davis, Davis, United States
| | - Luis F Santana
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, United States
| | - Bertil Hille
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
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