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Kunisawa K, Hatanaka N, Shimizu T, Kobayashi K, Osanai Y, Mouri A, Shi Q, Bhat MA, Nambu A, Ikenaka K. Focal loss of the paranodal domain protein Neurofascin155 in the internal capsule impairs cortically induced muscle activity in vivo. Mol Brain 2020; 13:159. [PMID: 33228720 PMCID: PMC7685608 DOI: 10.1186/s13041-020-00698-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 11/13/2020] [Indexed: 11/12/2022] Open
Abstract
Paranodal axoglial junctions are essential for rapid nerve conduction and the organization of axonal domains in myelinated axons. Neurofascin155 (Nfasc155) is a glial cell adhesion molecule that is also required for the assembly of these domains. Previous studies have demonstrated that general ablation of Nfasc155 disorganizes these domains, reduces conduction velocity, and disrupts motor behaviors. Multiple sclerosis (MS), a typical disorder of demyelination in the central nervous system, is reported to have autoantibody to Nfasc. However, the impact of focal loss of Nfasc155, which may occur in MS patients, remains unclear. Here, we examined whether restricted focal loss of Nfasc155 affects the electrophysiological properties of the motor system in vivo. Adeno-associated virus type5 (AAV5) harboring EGFP-2A-Cre was injected into the glial-enriched internal capsule of floxed-Neurofascin (NfascFlox/Flox) mice to focally disrupt paranodal junctions in the cortico-fugal fibers from the motor cortex to the spinal cord. Electromyograms (EMGs) of the triceps brachii muscles in response to electrical stimulation of the motor cortex were successively examined in these awake mice. EMG analysis showed significant delay in the onset and peak latencies after AAV injection compared to control (Nfasc+/+) mice. Moreover, EMG half-widths were increased, and EMG amplitudes were gradually decreased by 13 weeks. Similar EMG changes have been reported in MS patients. These findings provide physiological evidence that motor outputs are obstructed by focal ablation of paranodal junctions in myelinated axons. Our findings may open a new path toward development of a novel biomarker for an early phase of human MS, as Nfasc155 detects microstructural changes in the paranodal junction.
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Affiliation(s)
- Kazuo Kunisawa
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, 444-8787, Japan
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
- Department of Regulatory Science for Evaluation and Development of Pharmaceuticals and Devices, Fujita Health University Graduate School of Health Sciences, Toyoake, 470-1192, Japan
| | - Nobuhiko Hatanaka
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan.
- Division of System Neurophysiology, National Institute for Physiological Sciences, 38 Nishigonaka, Myodaiji, Okazaki, 444-8585, Japan.
| | - Takeshi Shimizu
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, 444-8787, Japan
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
- Department of Neurophysiology and Brain Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan
| | - Kenta Kobayashi
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
- Section of Viral Vector Development, National Institute for Physiological Sciences, Okazaki, 444-8585, Japan
| | - Yasuyuki Osanai
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, 444-8787, Japan
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
| | - Akihiro Mouri
- Department of Regulatory Science for Evaluation and Development of Pharmaceuticals and Devices, Fujita Health University Graduate School of Health Sciences, Toyoake, 470-1192, Japan
| | - Qian Shi
- Department of Cellular and Integrative Physiology, School of Medicine, University of Texas Health Science Center, San Antonio, 78229-3900, USA
| | - Manzoor A Bhat
- Department of Cellular and Integrative Physiology, School of Medicine, University of Texas Health Science Center, San Antonio, 78229-3900, USA
| | - Atsushi Nambu
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
- Division of System Neurophysiology, National Institute for Physiological Sciences, 38 Nishigonaka, Myodaiji, Okazaki, 444-8585, Japan
| | - Kazuhiro Ikenaka
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, 444-8787, Japan
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
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Maldonado O, Jenkins A, Belalcazar HM, Hernandez-Cuervo H, Hyman KM, Ladaga G, Padilla L, de Erausquin GA. Age-dependent neuroprotective effect of an SK3 channel agonist on excitotoxity to dopaminergic neurons in organotypic culture. PLoS One 2020; 15:e0223633. [PMID: 32701951 PMCID: PMC7377472 DOI: 10.1371/journal.pone.0223633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 07/06/2020] [Indexed: 11/19/2022] Open
Abstract
Background Small conductance, calcium-activated (SK3) potassium channels control the intrinsic excitability of dopaminergic neurons (DN) in the midbrain and modulate their susceptibility to toxic insults during development. Methods We evaluated the age-dependency of the neuroprotective effect of an SK3 agonist, 1-Ethyl-1,3-dihydro-2H-benzimidazol-2-one (1-EBIO), on Amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) excitotoxicity to DN in ventral mesencephalon (VM) organotypic cultures. Results Most tyrosine hydroxylase (TH)+ neurons were also SK3+; SK3+/TH- cells (DN+) were common at each developmental stage but more prominently at day in vitro (DIV) 8. Young DN+ neurons were small bipolar and fusiform, whereas mature ones were large and multipolar. Exposure of organotypic cultures to AMPA (100 μm, 16 h) had no effect on the survival of DN+ at DIV 8, but caused significant toxicity at DIV 15 (n = 15, p = 0.005) and DIV 22 (n = 15, p<0.001). These results indicate that susceptibility of DN to AMPA excitotoxicity is developmental stage-dependent in embryonic VM organotypic cultures. Immature DN+ (small, bipolar) were increased after AMPA (100 μm, 16 h) at DIV 8, at the expense of the number of differentiated (large, multipolar) DN+ (p = 0.039). This effect was larger at DIV 15 (p<<<0.0001) and at DIV 22 (p<<<0.0001). At DIV 8, 30 μM 1-EBIO resulted in a large increase in DN+. At DIV 15, AMPA toxicity was prevented by exposure to 30 μM, but not 100 μM 1-EBIO. At DIV 22, excitotoxicity was unaffected by 30 μM 1-EBIO, and partially reduced by 100 μM 1-EBIO. Conclusion The effects of the SK3 channel agonist 1-EBIO on the survival of SK3-expressing dopaminergic neurons were concentration-dependent and influenced by neuronal developmental stage.
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Affiliation(s)
- Oscar Maldonado
- Laboratory of Brain Development, and Repair, Biggs Institute for Alzheimer and Neurodegenerative Diseases, University of Texas Health San Antonio, San Antonio, Texas, United States of America
| | - Alexandra Jenkins
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Helen M. Belalcazar
- Department of Genetics, Albert Einstein College of Medicine, New York City, New York, United States of America
| | - Helena Hernandez-Cuervo
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Katelynn M. Hyman
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Giannina Ladaga
- Laboratory of Brain Development, and Repair, Biggs Institute for Alzheimer and Neurodegenerative Diseases, University of Texas Health San Antonio, San Antonio, Texas, United States of America
| | - Lucia Padilla
- Laboratory of Brain Development, and Repair, Biggs Institute for Alzheimer and Neurodegenerative Diseases, University of Texas Health San Antonio, San Antonio, Texas, United States of America
| | - Gabriel A. de Erausquin
- Laboratory of Brain Development, and Repair, Biggs Institute for Alzheimer and Neurodegenerative Diseases, University of Texas Health San Antonio, San Antonio, Texas, United States of America
- * E-mail:
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