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Sumino A, Sumikama T, Shibata M, Irie K. Voltage sensors of a Na + channel dissociate from the pore domain and form inter-channel dimers in the resting state. Nat Commun 2023; 14:7835. [PMID: 38114487 PMCID: PMC10730821 DOI: 10.1038/s41467-023-43347-3] [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: 04/27/2023] [Accepted: 11/07/2023] [Indexed: 12/21/2023] Open
Abstract
Understanding voltage-gated sodium (Nav) channels is significant since they generate action potential. Nav channels consist of a pore domain (PD) and a voltage sensor domain (VSD). All resolved Nav structures in different gating states have VSDs that tightly interact with PDs; however, it is unclear whether VSDs attach to PDs during gating under physiological conditions. Here, we reconstituted three different voltage-dependent NavAb, which is cloned from Arcobacter butzleri, into a lipid membrane and observed their structural dynamics by high-speed atomic force microscopy on a sub-second timescale in the steady state. Surprisingly, VSDs dissociated from PDs in the mutant in the resting state and further dimerized to form cross-links between channels. This dimerization would occur at a realistic channel density, offering a potential explanation for the facilitation of positive cooperativity of channel activity in the rising phase of the action potential.
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Affiliation(s)
- Ayumi Sumino
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kanazawa, 920-1192, Japan.
- Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, 920-1192, Japan.
| | - Takashi Sumikama
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kanazawa, 920-1192, Japan.
| | - Mikihiro Shibata
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kanazawa, 920-1192, Japan
- Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, 920-1192, Japan
| | - Katsumasa Irie
- Department of Biophysical chemistry School of Pharmaceutical Science, Wakayama Medical University, Wakayama, 640-8156, Japan.
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2
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Ghovanloo MR, Ruben PC. Cannabidiol and Sodium Channel Pharmacology: General Overview, Mechanism, and Clinical Implications. Neuroscientist 2021; 28:318-334. [PMID: 34027742 PMCID: PMC9344566 DOI: 10.1177/10738584211017009] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium (Nav) channels initiate action potentials in excitable tissues. Altering these channels' function can lead to many pathophysiological conditions. Nav channels are composed of several functional and structural domains that could be targeted pharmacologically as potential therapeutic means against various neurological conditions. Mutations in Nav channels have been suggested to underlie various clinical syndromes in different tissues and in association with conditions ranging from epileptic to muscular problems. Treating those mutations that increase the excitability of Nav channels requires inhibitors that could effectively reduce channel firing. The main non-psychotropic constituent of the cannabis plant, cannabidiol (CBD), has recently gained interest as a viable compound to treat some of the conditions that are associated with Nav malfunctions. In this review, we discuss an overview of Nav channels followed by an in-depth description of the interactions of CBD and Nav channels. We conclude with some clinical implications of CBD use against Nav hyperexcitability based on a series of preclinical studies published to date, with a focus on Nav/CBD interactions.
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Affiliation(s)
- Mohammad-Reza Ghovanloo
- Department of Biomedical Physiology & Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada.,Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.,Center for Neuroscience & Regeneration Research, Yale University, West Haven, CT, USA
| | - Peter C Ruben
- Department of Biomedical Physiology & Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
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3
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Edvinsson L, Haanes KA. Identifying New Antimigraine Targets: Lessons from Molecular Biology. Trends Pharmacol Sci 2021; 42:217-225. [PMID: 33495027 DOI: 10.1016/j.tips.2021.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 12/22/2020] [Accepted: 01/04/2021] [Indexed: 02/07/2023]
Abstract
Primary headaches are one of the most common conditions; migraine being most prevalent. Recent work on the pathophysiology of migraine suggests a mismatch in the communication or tuning of the trigeminovascular system, leading to sensitization and the release of calcitonin gene-related peptide (CGRP). In the current Opinion, we use the up-to-date molecular understanding of mechanisms behind migraine pain, to provide novel aspects on how to modify the system and for the development of future treatments; acute as well as prophylactic. We explore the distribution and the expression of neuropeptides themselves, as well as certain ion channels, and most importantly how they may act in concert as modulators of excitability of both the trigeminal C neurons and the Aδ neurons.
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Affiliation(s)
- Lars Edvinsson
- Department of Clinical Experimental Research, Copenhagen University Hospital, Rigshospitalet-Glostrup, Denmark; Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Lund, Sweden.
| | - Kristian Agmund Haanes
- Department of Clinical Experimental Research, Copenhagen University Hospital, Rigshospitalet-Glostrup, Denmark
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4
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Kalafatakis I, Savvaki M, Velona T, Karagogeos D. Implication of Contactins in Demyelinating Pathologies. Life (Basel) 2021; 11:life11010051. [PMID: 33451101 PMCID: PMC7828632 DOI: 10.3390/life11010051] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/09/2021] [Accepted: 01/11/2021] [Indexed: 12/19/2022] Open
Abstract
Demyelinating pathologies comprise of a variety of conditions where either central or peripheral myelin is attacked, resulting in white matter lesions and neurodegeneration. Myelinated axons are organized into molecularly distinct domains, and this segregation is crucial for their proper function. These defined domains are differentially affected at the different stages of demyelination as well as at the lesion and perilesion sites. Among the main players in myelinated axon organization are proteins of the contactin (CNTN) group of the immunoglobulin superfamily (IgSF) of cell adhesion molecules, namely Contactin-1 and Contactin-2 (CNTN1, CNTN2). The two contactins perform their functions through intermolecular interactions, which are crucial for myelinated axon integrity and functionality. In this review, we focus on the implication of these two molecules as well as their interactors in demyelinating pathologies in humans. At first, we describe the organization and function of myelinated axons in the central (CNS) and the peripheral (PNS) nervous system, further analyzing the role of CNTN1 and CNTN2 as well as their interactors in myelination. In the last section, studies showing the correlation of the two contactins with demyelinating pathologies are reviewed, highlighting the importance of these recognition molecules in shaping the function of the nervous system in multiple ways.
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5
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Afzali M, Pieciak T, Newman S, Garyfallidis E, Özarslan E, Cheng H, Jones DK. The sensitivity of diffusion MRI to microstructural properties and experimental factors. J Neurosci Methods 2021; 347:108951. [PMID: 33017644 PMCID: PMC7762827 DOI: 10.1016/j.jneumeth.2020.108951] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 08/27/2020] [Accepted: 09/15/2020] [Indexed: 12/13/2022]
Abstract
Diffusion MRI is a non-invasive technique to study brain microstructure. Differences in the microstructural properties of tissue, including size and anisotropy, can be represented in the signal if the appropriate method of acquisition is used. However, to depict the underlying properties, special care must be taken when designing the acquisition protocol as any changes in the procedure might impact on quantitative measurements. This work reviews state-of-the-art methods for studying brain microstructure using diffusion MRI and their sensitivity to microstructural differences and various experimental factors. Microstructural properties of the tissue at a micrometer scale can be linked to the diffusion signal at a millimeter-scale using modeling. In this paper, we first give an introduction to diffusion MRI and different encoding schemes. Then, signal representation-based methods and multi-compartment models are explained briefly. The sensitivity of the diffusion MRI signal to the microstructural components and the effects of curvedness of axonal trajectories on the diffusion signal are reviewed. Factors that impact on the quality (accuracy and precision) of derived metrics are then reviewed, including the impact of random noise, and variations in the acquisition parameters (i.e., number of sampled signals, b-value and number of acquisition shells). Finally, yet importantly, typical approaches to deal with experimental factors are depicted, including unbiased measures and harmonization. We conclude the review with some future directions and recommendations on this topic.
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Affiliation(s)
- Maryam Afzali
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, United Kingdom.
| | - Tomasz Pieciak
- AGH University of Science and Technology, Kraków, Poland; LPI, ETSI Telecomunicación, Universidad de Valladolid, Valladolid, Spain.
| | - Sharlene Newman
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA; Program of Neuroscience, Indiana University, Bloomington, IN 47405, USA.
| | - Eleftherios Garyfallidis
- Program of Neuroscience, Indiana University, Bloomington, IN 47405, USA; Department of Intelligent Systems Engineering, Indiana University, Bloomington, IN 47408, USA.
| | - Evren Özarslan
- Department of Biomedical Engineering, Linköping University, Linköping, Sweden; Center for Medical Image Science and Visualization, Linköping University, Linköping, Sweden.
| | - Hu Cheng
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA; Program of Neuroscience, Indiana University, Bloomington, IN 47405, USA.
| | - Derek K Jones
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, United Kingdom.
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6
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Patel A, Rumsey JW, Lorance C, Long CJ, Lee B, Tetard L, Lambert S, Hickman JJ. Myelination and Node of Ranvier Formation in a Human Motoneuron-Schwann Cell Serum-Free Coculture. ACS Chem Neurosci 2020; 11:2615-2623. [PMID: 32786317 DOI: 10.1021/acschemneuro.0c00287] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Myelination and node of Ranvier formation play an important role in the rapid conduction of nerve impulses, referred to as saltatory conduction, along axons in the peripheral nervous system. We report a human-human myelination model using human primary Schwann cells (SCs) and human-induced pluripotent stem-cell-derived motoneurons utilizing a serum-free medium supplemented with ascorbate to induce myelination, where 41.6% of SCs expressed the master transcription factor for myelination, early growth response protein 2. After 30 days in coculture, myelin segments were visualized using immunocytochemistry for myelin basic protein surrounding neurofilament-stained motor neuron axons, which was confirmed via 3D confocal Raman microscopy, a viable alternative for transmission electron microscopy analysis. The myelination efficiency was 65%, and clusters of voltage-gated sodium channels and the paranodal protein contactin-associated protein 1 indicated node of Ranvier formation. This model has applications to study remyelination and demyelinating diseases, including Charcot-Marie Tooth disorder, Guillian-Barre syndrome, and anti-myelin-associated glycoprotein peripheral neuropathy.
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Affiliation(s)
- Aakash Patel
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, Florida 32826, United States
| | - John W. Rumsey
- Hesperos Inc., 12501 Research Parkway, Suite 100, Orlando, Florida 32826, United States
| | - Case Lorance
- Hesperos Inc., 12501 Research Parkway, Suite 100, Orlando, Florida 32826, United States
| | - Christopher J. Long
- Hesperos Inc., 12501 Research Parkway, Suite 100, Orlando, Florida 32826, United States
| | - Briana Lee
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, Florida 32826, United States
| | - Laurene Tetard
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, Florida 32826, United States
| | - Stephen Lambert
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, Florida 32826, United States
| | - James J. Hickman
- NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, Florida 32826, United States
- Hesperos Inc., 12501 Research Parkway, Suite 100, Orlando, Florida 32826, United States
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Anderson CJ, Anderson DN, Pulst SM, Butson CR, Dorval AD. Neural selectivity, efficiency, and dose equivalence in deep brain stimulation through pulse width tuning and segmented electrodes. Brain Stimul 2020; 13:1040-1050. [PMID: 32278715 DOI: 10.1016/j.brs.2020.03.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 03/26/2020] [Accepted: 03/27/2020] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Achieving deep brain stimulation (DBS) dose equivalence is challenging, especially with pulse width tuning and directional contacts. Further, the precise effects of pulse width tuning are unknown, and recent reports of the effects of pulse width tuning on neural selectivity are at odds with classic biophysical studies. METHODS We created multicompartment neuron models for two axon diameters and used finite element modeling to determine extracellular influence from standard and segmented electrodes. We analyzed axon activation profiles and calculated volumes of tissue activated. RESULTS We find that long pulse widths focus the stimulation effect on small, nearby fibers, suppressing distant white matter tract activation (responsible for some DBS side effects) and improving battery utilization when equivalent activation is maintained for small axons. Directional leads enable similar benefits to a greater degree. Reexamining previous reports of short pulse stimulation reducing side effects, we explore a possible alternate explanation: non-dose equivalent stimulation may have resulted in reduced spread of neural activation. Finally, using internal capsule avoidance as an example in the context of subthalamic stimulation, we present a patient-specific model to show how long pulse widths could help increase the biophysical therapeutic window. DISCUSSION We find agreement with classic studies and predict that long pulse widths may focus the stimulation effect on small, nearby fibers and improve power consumption. While future pre-clinical and clinical work is necessary regarding pulse width tuning, it is clear that future studies must ensure dose equivalence, noting that energy- and charge-equivalent amplitudes do not result in equivalent spread of neural activation when changing pulse width.
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Affiliation(s)
- Collin J Anderson
- University of Utah Department of Neurology, Salt Lake City, UT, USA.
| | - Daria Nesterovich Anderson
- University of Utah Department of Biomedical Engineering, Salt Lake City, UT, USA; University of Utah Department of Neurosurgery, Salt Lake City, UT, USA; University of Utah Scientific Computing and Imaging Institute, Salt Lake City, UT, USA
| | - Stefan M Pulst
- University of Utah Department of Neurology, Salt Lake City, UT, USA
| | - Christopher R Butson
- University of Utah Department of Neurology, Salt Lake City, UT, USA; University of Utah Department of Biomedical Engineering, Salt Lake City, UT, USA; University of Utah Department of Neurosurgery, Salt Lake City, UT, USA; University of Utah Scientific Computing and Imaging Institute, Salt Lake City, UT, USA; University of Utah Department of Psychiatry, Salt Lake City, UT, USA
| | - Alan D Dorval
- University of Utah Department of Biomedical Engineering, Salt Lake City, UT, USA
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8
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Song GJ, Gupta DP, Rahman MH, Park HT, Al Ghouleh I, Bisello A, Lee MG, Park JY, Park HH, Jun JH, Chung KW, Choi BO, Suk K. Loss-of-function of EBP50 is a new cause of hereditary peripheral neuropathy: EBP50 functions in peripheral nerve system. Glia 2020; 68:1794-1809. [PMID: 32077526 DOI: 10.1002/glia.23805] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 02/04/2020] [Accepted: 02/07/2020] [Indexed: 12/12/2022]
Abstract
Finding causative genetic mutations is important in the diagnosis and treatment of hereditary peripheral neuropathies. This study was conducted to find new genes involved in the pathophysiology of hereditary peripheral neuropathy. We identified a new mutation in the EBP50 gene, which is co-segregated with neuropathic phenotypes, including motor and sensory deficit in a family with Charcot-Marie-Tooth disease. EBP50 is known to be important for the formation of microvilli in epithelial cells, and the discovery of this gene mutation allowed us to study the function of EBP50 in the nervous system. EBP50 was strongly expressed in the nodal and paranodal regions of sciatic nerve fibers, where Schwann cell microvilli contact the axolemma, and at the growth tips of primary Schwann cells. In addition, EBP50 expression was decreased in mouse models of peripheral neuropathy. Knockout mice were used to study EBP50 function in the peripheral nervous system. Interestingly motor function deficit and abnormal histology of nerve fibers were observed in EBP50+/- heterozygous mice at 12 months of age, but not 3 months. in vitro studies using Schwann cells showed that NRG1-induced AKT activation and migration were significantly reduced in cells overexpressing the I325V mutant of EBP50 or cells with knocked-down EBP50 expression. In conclusion, we show for the first time that loss of function due to EBP50 gene deficiency or mutation can cause peripheral neuropathy.
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Affiliation(s)
- Gyun Jee Song
- Department of Medical Science, Institute for Bio-Medical Convergence, Catholic Kwandong University, International St. Mary's Hospital, Incheon, Republic of Korea
| | - Deepak Prasad Gupta
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 Plus KNU Biomedical Convergence Program, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Md Habibur Rahman
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 Plus KNU Biomedical Convergence Program, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Hwan Tae Park
- Department of Molecular Neuroscience, College of Medicine, Dong-A University, Busan, Republic of Korea
| | - Imad Al Ghouleh
- Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Alessandro Bisello
- Department of Pharmacology and Chemical Biology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Maan-Gee Lee
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 Plus KNU Biomedical Convergence Program, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Jae-Yong Park
- School of Biosystems and Biomedical Sciences, College of Health Sciences, Korea University, Seoul, Republic of Korea
| | - Hyun Ho Park
- College of Pharmacy, Chung-Ang University, Seoul, Republic of Korea
| | - Jin Hyun Jun
- Department of Senior Healthcare, BK21 Plus Program, Graduate School of Eulji University, Department of Biomedical Laboratory Science, College of Health Science, Eulji University, Seongnam, Republic of Korea
| | - Ki Wha Chung
- Department of Biological Sciences, Kongju National University, Gongju, Republic of Korea
| | - Byung-Ok Choi
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Kyoungho Suk
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 Plus KNU Biomedical Convergence Program, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
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9
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Edvinsson JCA, Warfvinge K, Krause DN, Blixt FW, Sheykhzade M, Edvinsson L, Haanes KA. C-fibers may modulate adjacent Aδ-fibers through axon-axon CGRP signaling at nodes of Ranvier in the trigeminal system. J Headache Pain 2019; 20:105. [PMID: 31718551 PMCID: PMC6852900 DOI: 10.1186/s10194-019-1055-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Accepted: 10/29/2019] [Indexed: 02/01/2023] Open
Abstract
Background Monoclonal antibodies (mAbs) towards CGRP or the CGRP receptor show good prophylactic antimigraine efficacy. However, their site of action is still elusive. Due to lack of passage of mAbs across the blood-brain barrier the trigeminal system has been suggested a possible site of action because it lacks blood-brain barrier and hence is available to circulating molecules. The trigeminal ganglion (TG) harbors two types of neurons; half of which store CGRP and the rest that express CGRP receptor elements (CLR/RAMP1). Methods With specific immunohistochemistry methods, we demonstrated the localization of CGRP, CLR, RAMP1, and their locations related to expression of the paranodal marker contactin-associated protein 1 (CASPR). Furthermore, we studied functional CGRP release separately from the neuron soma and the part with only nerve fibers of the trigeminal ganglion, using an enzyme-linked immunosorbent assay. Results Antibodies towards CGRP and CLR/RAMP1 bind to two different populations of neurons in the TG and are found in the C- and the myelinated Aδ-fibers, respectively, within the dura mater and in trigeminal ganglion (TG). CASPR staining revealed paranodal areas of the different myelinated fibers inhabiting the TG and dura mater. Double immunostaining with CASPR and RAMP1 or the functional CGRP receptor antibody (AA58) revealed co-localization of the two peptides in the paranodal region which suggests the presence of the CGRP-receptor. Double immunostaining with CGRP and CASPR revealed that thin C-fibers have CGRP-positive boutons which often localize in close proximity to the nodal areas of the CGRP-receptor positive Aδ-fibers. These boutons are pearl-like synaptic structures, and we show CGRP release from fibers dissociated from their neuronal bodies. In addition, we found that adjacent to the CGRP receptor localization in the node of Ranvier there was PKA immunoreactivity (kinase stimulated by cAMP), providing structural possibility to modify conduction activity within the Aδ-fibers. Conclusion We observed a close relationship between the CGRP containing C-fibers and the Aδ-fibers containing the CGRP-receptor elements, suggesting a point of axon-axon interaction for the released CGRP and a site of action for gepants and the novel mAbs to alleviate migraine.
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Affiliation(s)
- Jacob C A Edvinsson
- Department of Clinical Experimental Research, Copenhagen University Hospital, Rigshospitalet-Glostrup, Copenhagen, Denmark.,Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences,
- University of Copenhagen, Copenhagen, Denmark
| | - Karin Warfvinge
- Department of Clinical Experimental Research, Copenhagen University Hospital, Rigshospitalet-Glostrup, Copenhagen, Denmark.,Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Lund, Sweden
| | - Diana N Krause
- Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Lund, Sweden.,Department of Pharmacology, School of Medicine, University of California at Irvine, Irvine, CA, USA
| | - Frank W Blixt
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Majid Sheykhzade
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences,
- University of Copenhagen, Copenhagen, Denmark
| | - Lars Edvinsson
- Department of Clinical Experimental Research, Copenhagen University Hospital, Rigshospitalet-Glostrup, Copenhagen, Denmark. .,Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Lund, Sweden.
| | - Kristian A Haanes
- Department of Clinical Experimental Research, Copenhagen University Hospital, Rigshospitalet-Glostrup, Copenhagen, Denmark
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Swiatczak B, Feldkaemper M, Schraermeyer U, Schaeffel F. Demyelination and shrinkage of axons in the retinal nerve fiber layer in chickens developing deprivation myopia. Exp Eye Res 2019; 188:107783. [PMID: 31473258 DOI: 10.1016/j.exer.2019.107783] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/16/2019] [Accepted: 08/29/2019] [Indexed: 12/30/2022]
Abstract
Placing diffusers in front of the eyes induces deprivation myopia in a variety of animal models. As a result of the low pass filtering of the retinal images, less spatial information is available to the retina which should reduce neural activity. Since it has been found that myelination of axons in the central nervous system is modulated by neuronal activity, we have studied whether ganglion cell axons may shrink in response to the restricted visual input. Young chickens were treated for 5 h or 7 days with frosted diffusers to induce deprivation myopia. Nerve fiber layer thickness was measured in vivo, using B-scan OCT. Refractive states were tracked by IR photoretinoscopy, and UV fundus reflectivity by a custom-built device which flashed an LED centered in the camera aperture and recorded pupil brightness after refractive errors were corrected by trial lenses. Moreover, structure and histology of the retinal nerve fibers layer (RNFL) were analyzed ex vivo using transmission electron microscopy and immunohistochemistry. Since chicks have both non-myelinated and myelinated fibers in their RNFL, the thickness of myelin sheaths (G ratio) was measured, as well as the percentage of myelinated axons and the diameters of unmyelinated axons. Short-term deprivation caused an increase in UV fundus reflectivity already after 5 h (measured as pixel grey levels in the pupil: 28 ± 5 vs. 36 ± 10, p < 0.05) and thinning of the myelin sheaths (higher G ratio), compared to untreated control eyes (0.74 ± 0.01 vs. 0.79 ± 0.03, p < 0.05). Neither axon diameters (0.81 ± 0.05 μm vs. 0.82 ± 0.15 μm) nor thickness of the RNFL had changed after only 5 h (42.9 ± 1.3 μm vs. 42.3 ± 2.5 μm). However, after 7 days of diffuser wear, axons had become thinner (0.56 ± 0.14 μm vs. 0.78 ± 0.09 μm vs, p < 0.05), which could explain the thinning of the RNFL (36.3 ± 2.7 μm vs. 42.1 ± 2.4 μm, p < 0.01). Furthermore, myopic eyes had 38% less myelinated axons than untreated eyes as determined by immunohistochemical labelling against myelin basic protein (immunopositive areas in the central retina 1406 ± 341 μm2 vs. 2185 ± 290 μm2 in controls, p < 0.001). Myelin sheaths in the remaining axons remained unchanged (G ratio 0.76 ± 0.02 vs. 0.76 ± 0.03). Our study shows that deprivation myopia is associated with a significant loss of myelinated axons and shrinkage of the axon diameters of certain fibers in the RNFL. Early changes were already detected after 5 h and were accompanied by an increased fundus reflectivity in UV light. These parameters could therefore serve as the biomarkers for myopia development, at least in the chicken.
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Affiliation(s)
- Barbara Swiatczak
- Section of Neurobiology of the Eye, Ophthalmic Research Institute, University of Tuebingen, Elfriede Aulhorn Str. 7, 72076, Tuebingen, Germany
| | - Marita Feldkaemper
- Section of Neurobiology of the Eye, Ophthalmic Research Institute, University of Tuebingen, Elfriede Aulhorn Str. 7, 72076, Tuebingen, Germany
| | - Ulrich Schraermeyer
- Experimental Vitreoretinal Surgery, Ophthalmic Research Institute, University of Tuebingen, Schleichstr. 12/1, 72076, Tuebingen, Germany
| | - Frank Schaeffel
- Section of Neurobiology of the Eye, Ophthalmic Research Institute, University of Tuebingen, Elfriede Aulhorn Str. 7, 72076, Tuebingen, Germany.
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11
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Ginsburger K, Matuschke F, Poupon F, Mangin JF, Axer M, Poupon C. MEDUSA: A GPU-based tool to create realistic phantoms of the brain microstructure using tiny spheres. Neuroimage 2019; 193:10-24. [DOI: 10.1016/j.neuroimage.2019.02.055] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 02/18/2019] [Accepted: 02/21/2019] [Indexed: 12/16/2022] Open
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12
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Henrich-Noack P, Nikitovic D, Neagu M, Docea AO, Engin AB, Gelperina S, Shtilman M, Mitsias P, Tzanakakis G, Gozes I, Tsatsakis A. The blood–brain barrier and beyond: Nano-based neuropharmacology and the role of extracellular matrix. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2019; 17:359-379. [DOI: 10.1016/j.nano.2019.01.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 01/11/2019] [Accepted: 01/28/2019] [Indexed: 12/13/2022]
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13
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Alexander DC, Dyrby TB, Nilsson M, Zhang H. Imaging brain microstructure with diffusion MRI: practicality and applications. NMR IN BIOMEDICINE 2019; 32:e3841. [PMID: 29193413 DOI: 10.1002/nbm.3841] [Citation(s) in RCA: 205] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 07/09/2017] [Accepted: 09/11/2017] [Indexed: 05/22/2023]
Abstract
This article gives an overview of microstructure imaging of the brain with diffusion MRI and reviews the state of the art. The microstructure-imaging paradigm aims to estimate and map microscopic properties of tissue using a model that links these properties to the voxel scale MR signal. Imaging techniques of this type are just starting to make the transition from the technical research domain to wide application in biomedical studies. We focus here on the practicalities of both implementing such techniques and using them in applications. Specifically, the article summarizes the relevant aspects of brain microanatomy and the range of diffusion-weighted MR measurements that provide sensitivity to them. It then reviews the evolution of mathematical and computational models that relate the diffusion MR signal to brain tissue microstructure, as well as the expanding areas of application. Next we focus on practicalities of designing a working microstructure imaging technique: model selection, experiment design, parameter estimation, validation, and the pipeline of development of this class of technique. The article concludes with some future perspectives on opportunities in this topic and expectations on how the field will evolve in the short-to-medium term.
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Affiliation(s)
- Daniel C Alexander
- Centre for Medical Image Computing (CMIC), Department of Computer Science, UCL (University College London), Gower Street, London, UK
| | - Tim B Dyrby
- Danish Research Centre for Magnetic Resonance, Center for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Markus Nilsson
- Clinical Sciences Lund, Department of Radiology, Lund University, Lund, Sweden
| | - Hui Zhang
- Centre for Medical Image Computing (CMIC), Department of Computer Science, UCL (University College London), Gower Street, London, UK
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McGonigal R, Barrie JA, Yao D, McLaughlin M, Cunningham ME, Rowan EG, Willison HJ. Glial Sulfatides and Neuronal Complex Gangliosides Are Functionally Interdependent in Maintaining Myelinating Axon Integrity. J Neurosci 2019; 39:63-77. [PMID: 30446529 PMCID: PMC6325269 DOI: 10.1523/jneurosci.2095-18.2018] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/12/2018] [Accepted: 11/01/2018] [Indexed: 11/21/2022] Open
Abstract
Sulfatides and gangliosides are raft-associated glycolipids essential for maintaining myelinated nerve integrity. Mice deficient in sulfatide (cerebroside sulfotransferase knock-out, CST-/-) or complex gangliosides (β-1,4-N-acetylegalactosaminyltransferase1 knock-out, GalNAc-T-/-) display prominent disorganization of proteins at the node of Ranvier (NoR) in early life and age-dependent neurodegeneration. Loss of neuronal rather than glial complex gangliosides underpins the GalNAc-T-/- phenotype, as shown by neuron- or glial-specific rescue, whereas sulfatide is principally expressed and functional in glial membranes. The similarities in NoR phenotype of CST-/-, GalNAc-T-/-, and axo-glial protein-deficient mice suggests that these glycolipids stabilize membrane proteins including neurofascin155 (NF155) and myelin-associated glycoprotein (MAG) at axo-glial junctions. To assess the functional interactions between sulfatide and gangliosides, CST-/- and GalNAc-T-/- genotypes were interbred. CST-/-× GalNAc-T-/- mice develop normally to postnatal day 10 (P10), but all die between P20 and P25, coinciding with peak myelination. Ultrastructural, immunohistological, and biochemical analysis of either sex revealed widespread axonal degeneration and disruption to the axo-glial junction at the NoR. In addition to sulfatide-dependent loss of NF155, CST-/- × GalNAc-T-/- mice exhibited a major reduction in MAG protein levels in CNS myelin compared with WT and single-lipid-deficient mice. The CST-/- × GalNAc-T-/- phenotype was fully restored to that of CST-/- mice by neuron-specific expression of complex gangliosides, but not by their glial-specific expression nor by the global expression of a-series gangliosides. These data indicate that sulfatide and complex b-series gangliosides on the glial and neuronal membranes, respectively, act in concert to promote NF155 and MAG in maintaining the stable axo-glial interactions essential for normal nerve function.SIGNIFICANCE STATEMENT Sulfatides and complex gangliosides are membrane glycolipids with important roles in maintaining nervous system integrity. Node of Ranvier maintenance in particular requires stable compartmentalization of multiple membrane proteins. The axo-glial adhesion molecules neurofascin155 (NF155) and myelin-associated glycoprotein (MAG) require membrane microdomains containing either sulfatides or complex gangliosides to localize and function effectively. The cooperative roles of these microdomains and associated proteins are unknown. Here, we show vital interdependent roles for sulfatides and complex gangliosides because double (but not single) deficiency causes a rapidly lethal phenotype at an early age. These findings suggest that sulfatides and complex gangliosides on opposing axo-glial membranes are responsible for essential tethering of the axo-glial junction proteins NF155 and MAG, which interact to maintain the nodal complex.
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Affiliation(s)
- Rhona McGonigal
- University of Glasgow, Institute of Infection, Immunity and Inflammation Glasgow G12 8TA, United Kingdom
| | - Jennifer A Barrie
- University of Glasgow, Institute of Infection, Immunity and Inflammation Glasgow G12 8TA, United Kingdom
| | - Denggao Yao
- University of Glasgow, Institute of Infection, Immunity and Inflammation Glasgow G12 8TA, United Kingdom
| | - Mark McLaughlin
- University of Glasgow, School of Veterinary Biosciences, Glasgow G61 1QH, United Kingdom, and
| | - Madeleine E Cunningham
- University of Glasgow, Institute of Infection, Immunity and Inflammation Glasgow G12 8TA, United Kingdom
| | - Edward G Rowan
- University of Strathclyde, Strathclyde Institute of Pharmacy and Biochemical Sciences, Glasgow G4 0RE, United Kingdom
| | - Hugh J Willison
- University of Glasgow, Institute of Infection, Immunity and Inflammation Glasgow G12 8TA, United Kingdom,
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15
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Experimental and Computational Studies on the Basic Transmission Properties of Electromagnetic Waves in Softmaterial Waveguides. Sci Rep 2018; 8:13824. [PMID: 30218066 PMCID: PMC6138705 DOI: 10.1038/s41598-018-32345-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 08/31/2018] [Indexed: 01/18/2023] Open
Abstract
Conventional waveguides are usually made of metallic materials, and they are effective pathways for the transmission of electromagnetic waves. A “Softmaterial waveguide”, by contrast, is supposed to be made of dielectric material and ionic fluids. In this work, by means of both experiment and computational simulation we examined one kind of softmaterial waveguide, which has the configuration of ionic fluids filled in and out of a dielectric tube. We investigated configurations with varied parameters, i.e., tube thickness from 0.2 mm to 5.0 mm, tube length of 2.0–12.0 cm, ionic concentration covering 4 orders of magnitude from 0.0002–2.0 mol/L, frequency of 10 Hz to 100 MHz for sine wave excitations, pulse duration of 5 ns to 100 ms for excitation pulses. We also mimicked the myelin sheath structure in myelinated axons in simulation. Both experimental and simulation results consistently showed a clear confinement effect for the energy flux of transmitting electromagnetic waves inside the dielectric tube, strongly supporting the model of softmaterail waveguide. The results revealed that the softmaterial waveguide had a low-pass nature, where the intensity of transmitted signals saturated at a duration of 10–100 μs for pulses, or cut off at frequency of 10–100 kHz for sine waves. And, the transmission efficiency increased with the thickness of the dielectric layer, as well as ion concentration of the solution. The results may help for a better understanding various electrical communication behaviors observed in biosystems, where a natural lipid membrane with bilateral fluids was suggested as the efficient pathway for pulsed neural impulses in a way similar to soliton-like electromagnetic pulses transmitting in a softmaterial waveguide.
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Spearman BS, Desai VH, Mobini S, McDermott MD, Graham JB, Otto KJ, Judy JW, Schmidt CE. Tissue-Engineered Peripheral Nerve Interfaces. ADVANCED FUNCTIONAL MATERIALS 2018; 28:1701713. [PMID: 37829558 PMCID: PMC10569514 DOI: 10.1002/adfm.201701713] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
Research on neural interfaces has historically concentrated on development of systems for the brain; however, there is increasing interest in peripheral nerve interfaces (PNIs) that could provide benefit when peripheral nerve function is compromised, such as for amputees. Efforts focus on designing scalable and high-performance sensory and motor peripheral nervous system interfaces. Current PNIs face several design challenges such as undersampling of signals from the thousands of axons, nerve-fiber selectivity, and device-tissue integration. To improve PNIs, several researchers have turned to tissue engineering. Peripheral nerve tissue engineering has focused on designing regeneration scaffolds that mimic normal nerve extracellular matrix composition, provide advanced microarchitecture to stimulate cell migration, and have mechanical properties like the native nerve. By combining PNIs with tissue engineering, the goal is to promote natural axon regeneration into the devices to facilitate close contact with electrodes; in contrast, traditional PNIs rely on insertion or placement of electrodes into or around existing nerves, or do not utilize materials to actively facilitate axon regeneration. This review presents the state-of-the-art of PNIs and nerve tissue engineering, highlights recent approaches to combine neural-interface technology and tissue engineering, and addresses the remaining challenges with foreign-body response.
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Affiliation(s)
- Benjamin S Spearman
- Crayton Pruitt Family Department of Biomedical Engineering, The University of Florida, 1275 Center Dr., BMS Building JG-56, 116131, Gainesville, FL 32611-6131
| | - Vidhi H Desai
- Department of Electrical and Computer Engineering, The University of Florida, 216 Larsen Hall, 116200, Gainesville, FL 32611-6200
- Nanoscience Institute for Medical and Engineering Technology, The University of Florida, 1041 Center Drive, 116621, Gainesville, FL 32611-6621
| | - Sahba Mobini
- Crayton Pruitt Family Department of Biomedical Engineering, The University of Florida, 1275 Center Dr., BMS Building JG-56, 116131, Gainesville, FL 32611-6131
| | - Matthew D McDermott
- Crayton Pruitt Family Department of Biomedical Engineering, The University of Florida, 1275 Center Dr., BMS Building JG-56, 116131, Gainesville, FL 32611-6131
- Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Dr., West Lafayette, IN 47907-2032
| | - James B Graham
- Crayton Pruitt Family Department of Biomedical Engineering, The University of Florida, 1275 Center Dr., BMS Building JG-56, 116131, Gainesville, FL 32611-6131
| | - Kevin J Otto
- Crayton Pruitt Family Department of Biomedical Engineering, The University of Florida, 1275 Center Dr., BMS Building JG-56, 116131, Gainesville, FL 32611-6131
- Nanoscience Institute for Medical and Engineering Technology, The University of Florida, 1041 Center Drive, 116621, Gainesville, FL 32611-6621
- Department of Neuroscience, The University of Florida, 1149 Newell Dr., Room L1-100, 100244, Gainesville, FL 32610-0244
- Department of Neurology, The University of Florida, 2000 SW Archer Rd., Third Floor, 100383, Gainesville, FL 32610
| | - Jack W Judy
- Crayton Pruitt Family Department of Biomedical Engineering, The University of Florida, 1275 Center Dr., BMS Building JG-56, 116131, Gainesville, FL 32611-6131
- Department of Electrical and Computer Engineering, The University of Florida, 216 Larsen Hall, 116200, Gainesville, FL 32611-6200
- Nanoscience Institute for Medical and Engineering Technology, The University of Florida, 1041 Center Drive, 116621, Gainesville, FL 32611-6621
| | - Christine E Schmidt
- Crayton Pruitt Family Department of Biomedical Engineering, The University of Florida, 1275 Center Dr., BMS Building JG-56, 116131, Gainesville, FL 32611-6131
- Nanoscience Institute for Medical and Engineering Technology, The University of Florida, 1041 Center Drive, 116621, Gainesville, FL 32611-6621
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17
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Liang W, Zhang W, Zhao S, Liang H, Zhang J, Wang L. Alterations of Caspr2 and Nav1.6 on myelinated axon damage in a rat model of chronic cerebral hypoperfusion. Exp Ther Med 2017; 13:2468-2472. [PMID: 28565865 PMCID: PMC5443296 DOI: 10.3892/etm.2017.4228] [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: 06/13/2016] [Accepted: 01/11/2017] [Indexed: 11/19/2022] Open
Abstract
Myelinated axons require the correct localization of key proteins that are essential for nerve conduction and cognitive function. Little is known regarding the altered expression of contactin-associated protein 2 (Caspr2) at the juxtaparanodal regions and Nav1.6 at the node of Ranvier in response to chronic cerebral hypoperfusion (CCH). The aim of the present study was to examine the alterations in the key protein of myelinated axons and the potential mechanisms that may follow CCH. We established a rat model of CCH by controllable partial narrowing of bilateral common carotid arteries. Then, we detected cerebral blood flow (CBF) after surgery. We also evaluated motor-evoked potentials (MEPs), assessed the Morris water maze test, analyzed Caspr2 expression through immunohistochemistry and Nav1.6 protein expression through western blot analysis at 2, 4 and 12 weeks. The results revealed that the mean CBF value was significantly decreased to 33.90±5.48%. The MEP latencies and the escaping latencies were significantly prolonged. There was also an elongation of the first time passing of the hidden platform with a reduction of crossing platform times in spatial probing. Furthermore, the Caspr2 immunoreactivity demonstrated that the Caspr2 level was significantly downregulated with abnormal locations in the corpus callosum. The western blot analysis of Nav1.6 protein revealed that the level was reduced significantly over time. The results demonstrate that CCH leads to central conductive function loss, cognitive function damage and alterations in the key protein of myelinated axons, which may provide a molecular basis and key link for white matter damage.
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Affiliation(s)
- Weihua Liang
- No. 263 Clinic of PLA Army General Hospital, Beijing 101149, P.R. China.,Department of Neurology, Xinqiao Hospital, The Third Military Medical University, Chongqing 400038, P.R. China
| | - Weiwei Zhang
- PLA Army General Hospital, Beijing 100700, P.R. China
| | - Shifu Zhao
- Department of Neurology, Xinqiao Hospital, The Third Military Medical University, Chongqing 400038, P.R. China
| | - Hua Liang
- The 66083rd of PLA, Beijing 102488, P.R. China
| | - Jinli Zhang
- No. 263 Clinic of PLA Army General Hospital, Beijing 101149, P.R. China
| | - Luyan Wang
- No. 263 Clinic of PLA Army General Hospital, Beijing 101149, P.R. China
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18
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Amyloid precursor protein modulates Nav1.6 sodium channel currents through a Go-coupled JNK pathway. Sci Rep 2016; 6:39320. [PMID: 28008944 PMCID: PMC5180232 DOI: 10.1038/srep39320] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 11/17/2016] [Indexed: 02/08/2023] Open
Abstract
Amyloid precursor protein (APP), commonly associated with Alzheimer’s disease, also marks axonal degeneration. In the recent studies, we demonstrated that APP aggregated at nodes of Ranvier (NORs) in myelinated central nervous system (CNS) axons and interacted with Nav1.6. However, the physiological function of APP remains unknown. In this study, we described reduced sodium current densities in APP knockout hippocampal neurons. Coexpression of APP or its intracellular domains containing a VTPEER motif with Nav1.6 sodium channels in Xenopus oocytes resulted in an increase in peak sodium currents, which was enhanced by constitutively active Go mutant and blocked by a dominant negative mutant. JNK and CDK5 inhibitor attenuated increases in Nav1.6 sodium currents induced by overexpression of APP. Nav1.6 sodium currents were increased by APPT668E (mutant Thr to Glu) and decreased by T668A (mutant Thr to ALa) mutant, respectively. The cell surface expression of Nav1.6 sodium channels in the white matter of spinal cord and the spinal conduction velocity is decreased in APP, p35 and JNK3 knockout mice. Therefore, APP modulates Nav1.6 sodium channels through a Go-coupled JNK pathway, which is dependent on phosphorylation of APP at Thr668.
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19
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Leo-Macias A, Agullo-Pascual E, Sanchez-Alonso JL, Keegan S, Lin X, Arcos T, Feng-Xia-Liang, Korchev YE, Gorelik J, Fenyö D, Rothenberg E, Rothenberg E, Delmar M. Nanoscale visualization of functional adhesion/excitability nodes at the intercalated disc. Nat Commun 2016; 7:10342. [PMID: 26787348 PMCID: PMC4735805 DOI: 10.1038/ncomms10342] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 12/01/2015] [Indexed: 02/06/2023] Open
Abstract
Intercellular adhesion and electrical excitability are considered separate cellular properties. Studies of myelinated fibres, however, show that voltage-gated sodium channels (VGSCs) aggregate with cell adhesion molecules at discrete subcellular locations, such as the nodes of Ranvier. Demonstration of similar macromolecular organization in cardiac muscle is missing. Here we combine nanoscale-imaging (single-molecule localization microscopy; electron microscopy; and ‘angle view' scanning patch clamp) with mathematical simulations to demonstrate distinct hubs at the cardiac intercalated disc, populated by clusters of the adhesion molecule N-cadherin and the VGSC NaV1.5. We show that the N-cadherin-NaV1.5 association is not random, that NaV1.5 molecules in these clusters are major contributors to cardiac sodium current, and that loss of NaV1.5 expression reduces intercellular adhesion strength. We speculate that adhesion/excitability nodes are key sites for crosstalk of the contractile and electrical molecular apparatus and may represent the structural substrate of cardiomyopathies in patients with mutations in molecules of the VGSC complex. In myelinated fibres conduction and adhesion proteins aggregate at discrete foci, but it is unclear if this organization is present in other excitable cells. Using nanoscale visualization and in silico techniques, the authors show that adhesion/excitability nodes exist at the intercalated discs of adult cardiac muscle.
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Affiliation(s)
- Alejandra Leo-Macias
- The Leon H Charney Division of Cardiology, New York University School of Medicine (NYU-SoM), 522 First Avenue, Smilow 805, New York, New York 10016, USA
| | - Esperanza Agullo-Pascual
- The Leon H Charney Division of Cardiology, New York University School of Medicine (NYU-SoM), 522 First Avenue, Smilow 805, New York, New York 10016, USA
| | - Jose L Sanchez-Alonso
- Imperial College, National Heart and Lung Institute, Department of Cardiac Medicine, Imperial Center for Translational and Experimental Medicine, Hammersmith Campus, Du Cane Road, London W12 0NN, UK
| | - Sarah Keegan
- Center for Health Informatics and Bioinformatics, NYU-SoM, Translational Research Building, 227 East 30th Street, New York, New York 10016, USA
| | - Xianming Lin
- The Leon H Charney Division of Cardiology, New York University School of Medicine (NYU-SoM), 522 First Avenue, Smilow 805, New York, New York 10016, USA
| | - Tatiana Arcos
- The Leon H Charney Division of Cardiology, New York University School of Medicine (NYU-SoM), 522 First Avenue, Smilow 805, New York, New York 10016, USA
| | - Feng-Xia-Liang
- Microscopy Core, NYU-SoM, 522 First Avenue, Skirball Institute, 2nd Floor, New York, New York 10016, USA
| | - Yuri E Korchev
- Division of Medicine, Imperial College, Hammersmith Campus, Du Cane Road, London, London W12 0NN, UK
| | - Julia Gorelik
- Imperial College, National Heart and Lung Institute, Department of Cardiac Medicine, Imperial Center for Translational and Experimental Medicine, Hammersmith Campus, Du Cane Road, London W12 0NN, UK
| | - David Fenyö
- Center for Health Informatics and Bioinformatics, NYU-SoM, Translational Research Building, 227 East 30th Street, New York, New York 10016, USA
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, NYU-SoM, 522 First Avenue, MSB 3rd Floor, New York, New York 10016, USA
| | | | - Mario Delmar
- The Leon H Charney Division of Cardiology, New York University School of Medicine (NYU-SoM), 522 First Avenue, Smilow 805, New York, New York 10016, USA
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20
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Srinivasan A, Tipton J, Tahilramani M, Kharbouch A, Gaupp E, Song C, Venkataraman P, Falcone J, Lacour SP, Stanley GB, English AW, Bellamkonda RV. A regenerative microchannel device for recording multiple single-unit action potentials in awake, ambulatory animals. Eur J Neurosci 2015; 43:474-85. [PMID: 26370722 DOI: 10.1111/ejn.13080] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 08/07/2015] [Accepted: 09/08/2015] [Indexed: 12/28/2022]
Abstract
Despite significant advances in robotics, commercially advanced prosthetics provide only a small fraction of the functionality of the amputated limb that they are meant to replace. Peripheral nerve interfacing could provide a rich controlling link between the body and these advanced prosthetics in order to increase their overall utility. Here, we report on the development of a fully integrated regenerative microchannel interface with 30 microelectrodes and signal extraction capabilities enabling evaluation in an awake and ambulatory rat animal model. In vitro functional testing validated the capability of the microelectrodes to record neural signals similar in size and nature to those that occur in vivo. In vitro dorsal root ganglia cultures revealed striking cytocompatibility of the microchannel interface. Finally, in vivo, the microchannel interface was successfully used to record a multitude of single-unit action potentials through 63% of the integrated microelectrodes at the early time point of 3 weeks. This marks a significant advance in microchannel interfacing, demonstrating the capability of microchannels to be used for peripheral nerve interfacing.
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Affiliation(s)
- Akhil Srinivasan
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, 313 Ferst Drive, Atlanta, GA, 30332, USA
| | - John Tipton
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, 313 Ferst Drive, Atlanta, GA, 30332, USA
| | - Mayank Tahilramani
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, 313 Ferst Drive, Atlanta, GA, 30332, USA
| | - Adel Kharbouch
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, 313 Ferst Drive, Atlanta, GA, 30332, USA
| | - Eric Gaupp
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, 313 Ferst Drive, Atlanta, GA, 30332, USA
| | - Chao Song
- School of Electrical and Computer Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA, USA
| | - Poornima Venkataraman
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, 313 Ferst Drive, Atlanta, GA, 30332, USA
| | - Jessica Falcone
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, 313 Ferst Drive, Atlanta, GA, 30332, USA
| | - Stéphanie P Lacour
- Centre for Neuroprosthetics, School of Engineering, Institute of Microengineering and Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne, Switzerland
| | - Garrett B Stanley
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, 313 Ferst Drive, Atlanta, GA, 30332, USA
| | - Arthur W English
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - Ravi V Bellamkonda
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, 313 Ferst Drive, Atlanta, GA, 30332, USA
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21
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New insights into the roles of the contactin cell adhesion molecules in neural development. ADVANCES IN NEUROBIOLOGY 2014; 8:165-94. [PMID: 25300137 DOI: 10.1007/978-1-4614-8090-7_8] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In vertebrates, the contactin (CNTN) family of neural cell recognition molecules includes six related cell adhesion molecules that play non-overlapping roles in the formation and maintenance of the nervous system. CNTN1 and CNTN2 are the prototypical members of the family and have been involved, through cis- and trans-interactions with distinct cell adhesion molecules, in neural cell migration, axon guidance, and the organization of myelin subdomains. In contrast, the roles of CNTN3-6 are less well characterized although the generation of null mice and the recent identification of a common extracellular binding partner have considerably advanced our grasp of their physiological roles in particular as they relate to the wiring of sensory tissues. In this review, we aim to present a summary of our current understanding of CNTN functions and give an overview of the challenges that lie ahead in understanding the roles these proteins play in nervous system development and maintenance.
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22
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Zhang Y, Bekku Y, Dzhashiashvili Y, Armenti S, Meng X, Sasaki Y, Milbrandt J, Salzer JL. Assembly and maintenance of nodes of ranvier rely on distinct sources of proteins and targeting mechanisms. Neuron 2012; 73:92-107. [PMID: 22243749 DOI: 10.1016/j.neuron.2011.10.016] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2011] [Indexed: 01/29/2023]
Abstract
VIDEO ABSTRACT We have investigated the source(s) and targeting of components to PNS nodes of Ranvier. We show adhesion molecules are freely diffusible within the axon membrane and accumulate at forming nodes from local sources, whereas ion channels and cytoskeletal components are largely immobile and require transport to the node. We further characterize targeting of NF186, an adhesion molecule that pioneers node formation. NF186 redistributes to nascent nodes from a mobile, surface pool. Its initial accumulation and clearance from the internode require extracellular interactions, whereas targeting to mature nodes, i.e., those flanked by paranodal junctions, requires intracellular interactions. After incorporation into the node, NF186 is immobile, stable, and promotes node integrity. Thus, nodes assemble from two sources: adhesion molecules, which initiate assembly, accumulate by diffusion trapping via interactions with Schwann cells, whereas ion channels and cytoskeletal components accumulate via subsequent transport. In mature nodes, components turnover slowly and are replenished via transport.
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Affiliation(s)
- Yanqing Zhang
- Smilow Neuroscience Program, New York University Langone Medical Center, New York, NY 10016, USA
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Nualart-Marti A, Solsona C, Fields RD. Gap junction communication in myelinating glia. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:69-78. [PMID: 22326946 DOI: 10.1016/j.bbamem.2012.01.024] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 01/17/2012] [Accepted: 01/26/2012] [Indexed: 10/14/2022]
Abstract
Gap junction communication is crucial for myelination and axonal survival in both the peripheral nervous system (PNS) and central nervous system (CNS). This review examines the different types of gap junctions in myelinating glia of the PNS and CNS (Schwann cells and oligodendrocytes respectively), including their functions and involvement in neurological disorders. Gap junctions mediate intercellular communication among Schwann cells in the PNS, and among oligodendrocytes and between oligodendrocytes and astrocytes in the CNS. Reflexive gap junctions mediating transfer between different regions of the same cell promote communication between cellular compartments of myelinating glia that are separated by layers of compact myelin. Gap junctions in myelinating glia regulate physiological processes such as cell growth, proliferation, calcium signaling, and participate in extracellular signaling via release of neurotransmitters from hemijunctions. In the CNS, gap junctions form a glial network between oligodendrocytes and astrocytes. This transcellular communication is hypothesized to maintain homeostasis by facilitating restoration of membrane potential after axonal activity via electrical coupling and the re-distribution of potassium ions released from axons. The generation of transgenic mice for different subsets of connexins has revealed the contribution of different connexins in gap junction formation and illuminated new subcellular mechanisms underlying demyelination and cognitive defects. Alterations in metabolic coupling have been reported in animal models of X-linked Charcot-Marie-Tooth disease (CMTX) and Pelizaeus-Merzbarcher-like disease (PMLD), which are caused by mutations in the genes encoding for connexin 32 and connexin 47 respectively. Future research identifying the expression and regulation of gap junctions in myelinating glia is likely to provide a better understanding of myelinating glia in nervous system function, plasticity, and disease. This article is part of a Special Issue entitled: The Communicating junctions, roles and dysfunctions.
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Affiliation(s)
- Anna Nualart-Marti
- Department of Pathology and Experimental Therapeutics, University of Barcelona, Barcelona, Spain.
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Abstract
Regional nerve blocks are commonly used to provide analgesia for dental and oral surgical procedures. The purpose of this study was to demarcate the areas of the mandible that would be desensitized by application of the mental nerve block. Seven healthy mixed-breed dogs were anesthetized for an annual dental examination and professional teeth cleaning procedure. Bupivacaine HCl (0.4 ml/m2) was administered at one middle mental foramen based on previously described techniques for the mental nerve block. A noxious stimulus was applied at 23 predetermined ipsilateral mandibular locations using pressure from a mosquito hemostat on the mucocutaneous junction (MCJ) and a dental curette on the vestibular mucogingival line (MGL) at the incisor, canine, and premolar teeth; and, the mesial and distal aspects of the first molar tooth. A thermal stimulus using a refrigerant spray on a cotton ball was applied to the ipsilateral canine, third premolar, and fourth premolar teeth; and, the mesial and distal aspects of the first molar tooth. Demonstration of nociception or anesthesia was noted and the responses tabulated. The area of desensitized tissues was smaller than expected and highly variable within the study group. In conclusion, the unilateral mental nerve block does not reliably provide generalized desensitization to tissues of the incisive and rostral regions of the mandible. Although the mental nerve block is recommended, other modes of analgesia should be emphasized for surgical and dental procedures involving these areas.
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Affiliation(s)
- William Krug
- From the Dentistry and Oral Surgery Service, North Carolina State University, 4700 Hillsborough Street, Raleigh, NC 27606
| | - Jeannie Losey
- From the Dentistry and Oral Surgery Service, North Carolina State University, 4700 Hillsborough Street, Raleigh, NC 27606
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25
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Israeli E, Agmon-Levin N, Blank M, Chapman J, Shoenfeld Y. Guillain–Barré Syndrome—A Classical Autoimmune Disease Triggered by Infection or Vaccination. Clin Rev Allergy Immunol 2010; 42:121-30. [DOI: 10.1007/s12016-010-8213-3] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Dewitt DD, Kaszuba SN, Thompson DM, Stegemann JP. Collagen I-matrigel scaffolds for enhanced Schwann cell survival and control of three-dimensional cell morphology. Tissue Eng Part A 2009; 15:2785-93. [PMID: 19231925 DOI: 10.1089/ten.tea.2008.0406] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We report on the ability to control three-dimensional Schwann cell (SC) morphology using collagen I-Matrigel composite scaffolds for neural engineering applications. SCs are supportive of nerve regeneration after injury, and it has recently been reported that SCs embedded in collagen I, a material frequently used in guidance channel studies, do not readily extend processes, instead adopting a spherical morphology indicative of little interaction with the matrix. We have modified collagen I matrices by adding Matrigel to make them more supportive of SCs and characterized these matrices and SC morphology in vitro. Incorporation of 10%, 20%, 35%, and 50% Matrigel by volume resulted in 2.4, 3.5, 3.7, and 4.2 times longer average SC process length after 14 days in culture than with collagen I-only controls. Additionally, only 35% and 50% Matrigel constructs were able to maintain SC number over 14 days, whereas an 88% decrease in cells from initial seeding density was observed in collagen-only constructs over the same time period. Mechanical testing revealed that the addition of 50% Matrigel increased matrix stiffness from 6.4 kPa in collagen I-only constructs to 9.8 kPa. Furthermore, second harmonic generation imaging showed that the addition of Matrigel resulted in non-uniform distribution of collagen I, and scanning electron microscope imaging illustrated distinct differences in the fibrillar structure of the different constructs. Collectively, this work lays a foundation for developing scaffolding materials that are concurrently supportive of neurons and SCs for future neural engineering applications.
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Affiliation(s)
- Daniel D Dewitt
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA
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Salzer JL, Brophy PJ, Peles E. Molecular domains of myelinated axons in the peripheral nervous system. Glia 2009; 56:1532-1540. [PMID: 18803321 DOI: 10.1002/glia.20750] [Citation(s) in RCA: 159] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Myelinated axons are organized into a series of specialized domains with distinct molecular compositions and functions. These domains, which include the node of Ranvier, the flanking paranodal junctions, the juxtaparanodes, and the internode, form as the result of interactions with myelinating Schwann cells. This domain organization is essential for action potential propagation by saltatory conduction and for the overall function and integrity of the axon.
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Affiliation(s)
- James L Salzer
- Department of Cell Biology and Neurology, and the Smilow Neuroscience Program, NYU School of Medicine, New York, New York 10016, USA.
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Smit JE, Hanekom T, Hanekom JJ. Modelled temperature-dependent excitability behaviour of a single ranvier node for a human peripheral sensory nerve fibre. BIOLOGICAL CYBERNETICS 2009; 100:49-58. [PMID: 19066936 DOI: 10.1007/s00422-008-0280-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Accepted: 11/14/2008] [Indexed: 05/27/2023]
Abstract
The objective of this study was to determine whether the Hodgkin-Huxley model for unmyelinated nerve fibres could be modified to predict excitability behaviour at Ranvier nodes. Only the model parameters were modified to those of human, with the equations left unaltered. A model of a single Ranvier node has been developed as part of a larger model to describe excitation behaviour in a generalised human peripheral sensory nerve fibre. Parameter values describing the ionic and leakage conductances, corresponding equilibrium potentials, resting membrane potential and membrane capacitance of the original Hodgkin-Huxley model were modified to reflect the corresponding parameter values for human. Parameter temperature dependence was included. The fast activating potassium current kinetics were slowed down to represent those of a slow activating and deactivating potassium current, which do not inactivate. All calculations were performed in MATLAB. Action potential shape and amplitude were satisfactorily predicted at 20, 25 and 37 degrees C, and were not influenced by activation or deactivation of the slow potassium current. The calculated chronaxie time constant was 65.5 micros at 37 degrees C. However, chronaxie times were overestimated at temperatures lower than body temperature.
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Affiliation(s)
- Jacoba E Smit
- Department of Electrical, Electronic and Computer Engineering, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
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29
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Hoshikawa S, Ogata T, Fujiwara S, Nakamura K, Tanaka S. A novel function of RING finger protein 10 in transcriptional regulation of the myelin-associated glycoprotein gene and myelin formation in Schwann cells. PLoS One 2008; 3:e3464. [PMID: 18941509 PMCID: PMC2565066 DOI: 10.1371/journal.pone.0003464] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Accepted: 09/22/2008] [Indexed: 11/23/2022] Open
Abstract
Myelin-associated glycoprotein (MAG) has been detected in Schwann cells prior to the onset of myelination, suggesting its functions in the initiation of myelination. However, transcriptional regulatory mechanisms of MAG remain to be elucidated. Here, we analyzed the promoter of the MAG gene by using luciferase reporter systems in the primary rat Schwann cells. We identified a novel cis-acting element located 160 bp upstream from the MAG transcription initiation site. Using the identified cis-element as a bait, we performed yeast one-hybrid screening and isolated a cDNA encoding a RNF10 as a putative trans-acting protein. When overexpressed in Schwann cells, RNF10 enhanced the activity of the MAG promoter. When RNF10 expression in Schwann cells was knocked down by siRNA, endogenous MAG mRNA and protein expression decreased. Furthermore, we evaluated myelin synthesis using Schwann cell-DRG neuron cocultures. When Schwann cells were infected with retrovirus expressing RNF10 siRNA, myelin formation was inhibited. These data suggest that RNF10 regulates MAG expression and is required for myelin formation.
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Affiliation(s)
- Shinya Hoshikawa
- Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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30
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Savvaki M, Panagiotaropoulos T, Stamatakis A, Sargiannidou I, Karatzioula P, Watanabe K, Stylianopoulou F, Karagogeos D, Kleopa KA. Impairment of learning and memory in TAG-1 deficient mice associated with shorter CNS internodes and disrupted juxtaparanodes. Mol Cell Neurosci 2008; 39:478-90. [PMID: 18760366 DOI: 10.1016/j.mcn.2008.07.025] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2008] [Revised: 07/29/2008] [Accepted: 07/31/2008] [Indexed: 10/21/2022] Open
Abstract
The cell adhesion molecule TAG-1 is expressed by neurons and glial cells and plays a role in axon outgrowth, migration and fasciculation during development. TAG-1 is also required for the clustering of Kv1.1/1.2 potassium channels and Caspr2 at the juxtaparanodes of myelinated fibers. Behavioral examination of TAG-1 deficient mice (Tag-1(-/-)) showed cognitive impairments in the Morris water maze and novel object recognition tests, reduced spontaneous motor activity, abnormal gait coordination and increased response latency to noxious stimulation. Investigation at the molecular level revealed impaired juxtaparanodal clustering of Caspr2 and Kv1.1/1.2 in the hippocampus, entorhinal cortex, cerebellum and olfactory bulb, with diffusion into the internode. Caspr2 and Kv1.1 levels were reduced in the cerebellum and olfactory bulb. Moreover, Tag-1(-/-) mice had shorter internodes in the cerebral and cerebellar white matter. The detected molecular alterations may account for the behavioural deficits and hyperexcitability in these animals.
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Affiliation(s)
- Maria Savvaki
- Department of Basic Science, University of Crete Medical School, and Institute of Molecular Biology and Biotechnology, Heraklion, Greece
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Tanaka Y, Imai H, Konno K, Miyagishima T, Kubota C, Puentes S, Aoki T, Hata H, Takata K, Yoshimoto Y, Saito N. Experimental model of lacunar infarction in the gyrencephalic brain of the miniature pig: neurological assessment and histological, immunohistochemical, and physiological evaluation of dynamic corticospinal tract deformation. Stroke 2007; 39:205-12. [PMID: 18048856 DOI: 10.1161/strokeaha.107.489906] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND AND PURPOSE Lacunar infarction accounts for 25% of ischemic strokes, but the pathological characteristics have not been investigated systematically. A new experimental model of lacunar infarction in the miniature pig was developed to investigate the pathophysiological changes in the corticospinal tract from the acute to chronic phases. METHODS Thirty-five miniature pigs underwent transcranial surgery for permanent anterior choroidal artery occlusion. Animals recovered for 24 hours (n=7), 2 (n=5), 3 (n=2), 4 (n=2), 6 (n=1), 7 (n=7), 8 (n=2), and 9 days (n=1), 2 weeks (n=2), 4 weeks (n=3), and more than 4 weeks (n=3). Neurology, electrophysiology, histology, and MRI were performed. Seven additional miniature pigs underwent transient anterior choroidal artery occlusion to study muscle motor-evoked potentials and evaluate corticospinal tract function during transient anterior choroidal artery occlusion. RESULTS The protocol had a 91.4% success rate in induction of internal capsule infarction 286+/-153 mm(3) (mean+/-SD). Motor-evoked potentials revealed the presence of penumbral tissue in the internal capsule after 6 to 15 minutes anterior choroidal artery occlusion. Total neurological deficit scores of 15.0 (95% CI, 13.5 to 16.4) and 3.4 (0.3 to 6.4) were recorded for permanent anterior choroidal artery occlusion and sham groups, respectively (P<0.001, maximum score 25) with motor deficit scores of 3.4 (95% CI, 2.9 to 4.0) and 0.0 (CI, 0.0 to 0.0), respectively (P<0.001, maximum score 9). Histology revealed that the internal capsule lesion expands gradually from acute to chronic phases. CONCLUSIONS This new model of lacunar infarction induces a reproducible infarct in subcortical white matter with a measurable functional deficit and evidence of penumbral tissue acutely.
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Affiliation(s)
- Yukitaka Tanaka
- Department of Neurosurgery, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
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MIRSKY RHONA, PARMANTIER ERIC, MCMAHON ANDREWP, JESSEN KRISTJANR. Schwann Cell-Derived Desert Hedgehog Signals Nerve Sheath Formation. Ann N Y Acad Sci 2006; 883:196-202. [DOI: 10.1111/j.1749-6632.1999.tb08582.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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33
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Dalskov SM, Immerdal L, Niels-Christiansen LL, Hansen GH, Schousboe A, Danielsen EM. Lipid raft localization of GABAA receptor and Na+, K+-ATPase in discrete microdomain clusters in rat cerebellar granule cells. Neurochem Int 2005; 46:489-99. [PMID: 15769551 DOI: 10.1016/j.neuint.2004.11.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Revised: 11/29/2004] [Accepted: 11/30/2004] [Indexed: 12/20/2022]
Abstract
The microdomain localization of the GABA(A) receptor in rat cerebellar granule cells was studied by subcellular fractionation and fluorescence- and immunogold electron microscopy. The receptor resided in lipid rafts, prepared at 37 degrees C by extraction with the nonionic detergent Brij 98, but the raft fraction, defined by the marker ganglioside GM(1) in the floating fractions following density gradient centrifugation, was heterogeneous in density and protein composition. Thus, another major raft-associated membrane protein, the Na(+), K(+)-ATPase, was found in discrete rafts of lower density, reflecting clustering of the two proteins in separate membrane microdomains. Both proteins were observed in patchy "hot spots" at the cell surface as well as in isolated lipid rafts. Their insolubility in Brij 98 was only marginally affected by methyl-beta-cyclodextrin. In contrast, both the GABA(A) receptor and Na(+), K(+)-ATPase were largely soluble in ice cold Triton X-100. This indicates that Brij 98 extraction defines an unusual type of cholesterol-independent lipid rafts that harbour membrane proteins also associated with underlying scaffolding/cytoskeletal proteins such as gephyrin (GABA(A) receptor) and ankyrin G (Na(+), K(+)-ATPase). By providing an ordered membrane microenvironment, lipid rafts may contribute to the clustering of the GABA(A) receptor and the Na(+), K(+)-ATPase at distinct functional locations on the cell surface.
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Affiliation(s)
- Stine-Mathilde Dalskov
- Department of Medical Biochemistry and Genetics, The Panum Institute, University of Copenhagen, 3 Blegdamsvej, DK-2200 Copenhagen N, Denmark
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Casula MA, Facer P, Powell AJ, Kinghorn IJ, Plumpton C, Tate SN, Bountra C, Birch R, Anand P. Expression of the sodium channel beta3 subunit in injured human sensory neurons. Neuroreport 2004; 15:1629-32. [PMID: 15232296 DOI: 10.1097/01.wnr.0000134927.02776.ae] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Voltage-gated sodium channel alpha-subunits play a key role in pain pathophysiology, and are modulated by beta-subunits. We previously reported that beta1- and beta2-subunits were decreased in human sensory neurons after spinal root avulsion injury. We have now detected, by immunohistochemistry, beta3-subunits in 82% of small/medium and 67% of large diameter sensory neurons in intact human dorsal root ganglia: 54% of beta3 small/medium neurons were NGF receptor trkA negative. Unlike beta1- and beta2, beta3-immunoreactivity did not decrease after avulsion injury, and the beta3:neurofilament ratio was significantly increased in proximal injured human nerves. beta3-subunit expression may thus be regulated differently from beta1, beta2 and Nav1.8. Targeting beta3 interactions with key alpha-subunits, particularly Nav1.3 and Nav1.8, may provide novel selective analgesics.
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Affiliation(s)
- Maria A Casula
- Peripheral Neuropathy Unit, Imperial College London, Area A, Ground Floor, Hammersmith Hospital, Du Cane Rd, London W12 0NN, UK
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35
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Genova JL, Fehon RG. Neuroglian, Gliotactin, and the Na+/K+ ATPase are essential for septate junction function in Drosophila. J Cell Biol 2003; 161:979-89. [PMID: 12782686 PMCID: PMC2172966 DOI: 10.1083/jcb.200212054] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
One essential function of epithelia is to form a barrier between the apical and basolateral surfaces of the epithelium. In vertebrate epithelia, the tight junction is the primary barrier to paracellular flow across epithelia, whereas in invertebrate epithelia, the septate junction (SJ) provides this function. In this study, we identify new proteins that are required for a functional paracellular barrier in Drosophila. In addition to the previously known components Coracle (COR) and Neurexin (NRX), we show that four other proteins, Gliotactin, Neuroglian (NRG), and both the alpha and beta subunits of the Na+/K+ ATPase, are required for formation of the paracellular barrier. In contrast to previous reports, we demonstrate that the Na pump is not localized basolaterally in epithelial cells, but instead is concentrated at the SJ. Data from immunoprecipitation and somatic mosaic studies suggest that COR, NRX, NRG, and the Na+/K+ ATPase form an interdependent complex. Furthermore, the observation that NRG, a Drosophila homologue of vertebrate neurofascin, is an SJ component is consistent with the notion that the invertebrate SJ is homologous to the vertebrate paranodal SJ. These findings have implications not only for invertebrate epithelia and barrier functions, but also for understanding of neuron-glial interactions in the mammalian nervous system.
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Affiliation(s)
- Jennifer L Genova
- Department of Biology, Developmental, Cell, and Molecular Biology Group, Duke University, Durham, NC 27708, USA
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Murai KK, Nguyen LN, Irie F, Yamaguchi Y, Pasquale EB. Control of hippocampal dendritic spine morphology through ephrin-A3/EphA4 signaling. Nat Neurosci 2003; 6:153-60. [PMID: 12496762 DOI: 10.1038/nn994] [Citation(s) in RCA: 389] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2002] [Accepted: 11/22/2002] [Indexed: 11/10/2022]
Abstract
Communication between glial cells and neurons is emerging as a critical parameter of synaptic function. However, the molecular mechanisms underlying the ability of glial cells to modify synaptic structure and physiology are poorly understood. Here we describe a repulsive interaction that regulates postsynaptic morphology through the EphA4 receptor tyrosine kinase and its ligand ephrin-A3. EphA4 is enriched on dendritic spines of pyramidal neurons in the adult mouse hippocampus, and ephrin-A3 is localized on astrocytic processes that envelop spines. Activation of EphA4 by ephrin-A3 was found to induce spine retraction, whereas inhibiting ephrin/EphA4 interactions distorted spine shape and organization in hippocampal slices. Furthermore, spine irregularities in pyramidal neurons from EphA4 knockout mice and in slices transfected with kinase-inactive EphA4 indicated that ephrin/EphA4 signaling is critical for spine morphology. Thus, our data support a model in which transient interactions between the ephrin-A3 ligand and the EphA4 receptor regulate the structure of excitatory synaptic connections through neuroglial cross-talk.
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Affiliation(s)
- Keith K Murai
- The Burnham Institute, Neurobiology Program, 10901 North Torrey Pines Road, La Jolla, California 92037, USA
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Ishibashi T, Ikenaka K, Shimizu T, Kagawa T, Baba H. Initiation of sodium channel clustering at the node of Ranvier in the mouse optic nerve. Neurochem Res 2003; 28:117-25. [PMID: 12587670 DOI: 10.1023/a:1021608514646] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Ion fluxes in mammalian myelinated axons are restricted to the nodes of Ranvier, where, in particular, voltage-gated Na+ channels are clustered at a high density. The node of Ranvier is separated from the internode by two distinct domains of the axolemma, the paranode and the juxtaparanode. Each axonal domain is characterized by the presence of a specific protein complex. Although oligodendrocytes and/or myelin membranes are believed to play some instructive roles in the organization of axonal domains, the mechanisms leading to their localized distribution are not well understood. In this paper we focused on the involvement of myelin sheaths in this domain organization and examined the distribution of axonal components in the optic nerves of wild type, hypomyelinatingjimpy mice and demyelinating PLP transgenic mice. The results showed that the clustering of Na+ channels does not require junction-like structures to be formed between the glial processes and axons, but requires mature oligodendrocytes to be present in close vicinity.
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Affiliation(s)
- Tomoko Ishibashi
- Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan
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The neuronal adhesion protein TAG-1 is expressed by Schwann cells and oligodendrocytes and is localized to the juxtaparanodal region of myelinated fibers. J Neurosci 2002. [PMID: 11943804 DOI: 10.1523/jneurosci.22-08-03016.2002] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The neural cell adhesion molecule TAG-1, which is a glycosylphosphatidylinositol-linked member of the Ig superfamily, is expressed by various neuronal populations in the developing CNS and PNS. We demonstrate here that Schwann cells and oligodendrocytes also express TAG-1. In the PNS, TAG-1 is detected in ensheathing Schwann cells early postnatally and is maintained throughout adulthood. In mature myelinated fibers of the CNS and PNS, TAG-1 is localized to the juxtaparanodal region. The CNS of the UDP-galactose ceramide galactosyl transferase(-/-) (CGT(-/-)) mouse mutants, which do not synthesize the abundant galactolipids of myelin, display severely disrupted axoglial interactions at the paranodal region. In contrast, axoglial interactions in the PNS of these mutants are less affected. Interestingly, TAG-1 localization is completely undetected in myelinated fibers of the CNS. In the PNS of these mutants, TAG-1 abnormally localizes in the paranodal region. These data raise the intriguing possibility that TAG-1 localization in the juxtaparanodal area mediates, or at least requires, the axoglial contact normally displayed in this region. The abnormal localization of TAG-1 in the CGT mutants might contribute to the disrupted axoglial interactions observed in these animals.
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Feng ZP, Grigoriev N, Munno D, Lukowiak K, MacVicar BA, Goldberg JI, Syed NI. Development of Ca2+ hotspots between Lymnaea neurons during synaptogenesis. J Physiol 2002; 539:53-65. [PMID: 11850501 PMCID: PMC2290139 DOI: 10.1113/jphysiol.2001.013125] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Calcium (Ca2+) channel clustering at specific presynaptic sites is a hallmark of mature synapses. However, the spatial distribution patterns of Ca2+ channels at newly formed synapses have not yet been demonstrated. Similarly, it is unclear whether Ca2+ 'hotspots' often observed at the presynaptic sites are indeed target cell contact specific and represent a specialized mechanism by which Ca2+ channels are targeted to select synaptic sites. Utilizing both soma-soma paired (synapsed) and single neurons from the mollusk Lymnaea, we have tested the hypothesis that differential gradients of voltage-dependent Ca2+ signals develop in presynaptic neuron at its contact point with the postsynaptic neuron; and that these Ca2+ hotspots are target cell contact specific. Fura-2 imaging, or two-photon laser scanning microscopy of Calcium Green, was coupled with electrophysiological techniques to demonstrate that voltage-induced Ca2+ gradients (hotspots) develop in the presynaptic cell at its contact point with the postsynaptic neuron, but not in unpaired single cells. The incidence of Ca2+ hotspots coincided with the appearance of synaptic transmission between the paired cells, and these gradients were target cell contact specific. In contrast, the voltage-induced Ca2+ signal in unpaired neurons was uniformly distributed throughout the somata; a similar pattern of Ca2+ gradient was observed in the presynaptic neuron when it was soma-soma paired with a non-synaptic partner cell. Moreover, voltage clamp recording techniques, in conjunction with a fast, optical differential perfusion system, were used to demonstrate that the total whole-cell Ca2+ (or Ba2+) current density in single and paired cells was not significantly different. However, the amplitude of Ba2+ current was significantly higher in the presynaptic cell at its contact side with the postsynaptic neurons, compared with non-contacted regions. In summary, this study demonstrates that voltage-induced Ca2+ hotspots develop in the presynaptic cell, concomitant with the appearance of synaptic transmission between the soma-soma paired cells. The appearance of Ca2+ gradients in presynaptic neurons is target cell contact specific and is probably due to a spatial redistribution of existing channels during synaptogenesis.
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Affiliation(s)
- Zhong-Ping Feng
- Respiratory and Neuroscience Research Groups, Faculty of Medicine, University of Calgary, 3330-Hospital Drive, NW, Calgary, Alberta, Canada T2N 4N1
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Mathis C, Denisenko-Nehrbass N, Girault JA, Borrelli E. Essential role of oligodendrocytes in the formation and maintenance of central nervous system nodal regions. Development 2001; 128:4881-90. [PMID: 11731467 DOI: 10.1242/dev.128.23.4881] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The membrane of myelinated axons is divided into functionally distinct domains characterized by the enrichment of specific proteins. The mechanisms responsible for this organization have not been fully identified. To further address the role of oligodendrocytes in the functional segmentation of the axolemma in vivo, the distribution of nodal (Na+ channels, ankyrin G), paranodal (paranodin/contactin-associated-protein) and juxtaparanodal (Kv1.1 K+ channels) axonal markers, was studied in the brain of MBP-TK and jimpy mice. In MBP-TK transgenic mice, oligodendrocyte ablation was selectively induced by FIAU treatment before and during the onset of myelination. In jimpy mice, oligodendrocytes degenerate spontaneously within the first postnatal weeks after the onset of myelination. Interestingly, in MBP-TK mice treated for 1-20 days with FIAU, despite the ablation of more than 95% of oligodendrocytes, the protein levels of all tested nodal markers was unaltered. Nevertheless, these proteins failed to cluster in the nodal regions. By contrast, in jimpy mice, despite a diffused localization of paranodin, the formation of nodal clusters of Na+ channels and ankyrin G was observed. Furthermore, K+ channels clusters were transiently visible, but were in direct contact with nodal markers. These results demonstrate that the organization of functional domains in myelinated axons is oligodendrocyte dependent. They also show that the presence of these cells is a requirement for the maintenance of nodal and paranodal regions.
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Affiliation(s)
- C Mathis
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, INSERM/CNRS/ULP, BP 163, 67404 Illkirch Cedex, C.U. de Strasbourg, France
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Ratcliffe CF, Westenbroek RE, Curtis R, Catterall WA. Sodium channel beta1 and beta3 subunits associate with neurofascin through their extracellular immunoglobulin-like domain. J Cell Biol 2001; 154:427-34. [PMID: 11470829 PMCID: PMC2150779 DOI: 10.1083/jcb.200102086] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Sequence homology predicts that the extracellular domain of the sodium channel beta1 subunit forms an immunoglobulin (Ig) fold and functions as a cell adhesion molecule. We show here that beta1 subunits associate with neurofascin, a neuronal cell adhesion molecule that plays a key role in the assembly of nodes of Ranvier. The first Ig-like domain and second fibronectin type III-like domain of neurofascin mediate the interaction with the extracellular Ig-like domain of beta1, confirming the proposed function of this domain as a cell adhesion molecule. beta1 subunits localize to nodes of Ranvier with neurofascin in sciatic nerve axons, and beta1 and neurofascin are associated as early as postnatal day 5, during the period that nodes of Ranvier are forming. This association of beta1 subunit extracellular domains with neurofascin in developing axons may facilitate recruitment and concentration of sodium channel complexes at nodes of Ranvier.
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Affiliation(s)
- C F Ratcliffe
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
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42
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Berghs S, Ferracci F, Maksimova E, Gleason S, Leszczynski N, Butler M, De Camilli P, Solimena M. Autoimmunity to beta IV spectrin in paraneoplastic lower motor neuron syndrome. Proc Natl Acad Sci U S A 2001; 98:6945-50. [PMID: 11391009 PMCID: PMC34458 DOI: 10.1073/pnas.121170798] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Paraneoplastic neurological disorders may result from autoimmunity directed against antigens shared by the affected neurons and the associated cancer cells. We have recently reported the case of a woman with breast cancer and paraneoplastic lower motor neuron syndrome whose serum contained autoantibodies directed against axon initial segments and nodes of Ranvier of myelinated axons, including the axons of motoneurons. Here, we show that major targets of the autoantibodies of this patient are betaIVSigma1 spectrin and betaIV spectrin 140, two isoforms of the novel betaIV spectrin gene, as well as a neuronal surface epitope yet to be identified. Partial improvement of the neurological symptoms following cancer removal was associated with a drastic reduction in the titer of the autoantibodies against betaIV spectrin and nodal antigens in general, consistent with the autoimmune pathogenesis of the paraneoplastic lower motor neuron syndrome. The identification of betaIV spectrin isoforms and surface nodal antigens as novel autoimmune targets in lower motor neuron syndrome provide new insights into the pathogenesis of this severe neurological disease.
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Affiliation(s)
- S Berghs
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, CT 06510, USA
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43
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Boyle ME, Berglund EO, Murai KK, Weber L, Peles E, Ranscht B. Contactin orchestrates assembly of the septate-like junctions at the paranode in myelinated peripheral nerve. Neuron 2001; 30:385-97. [PMID: 11395001 DOI: 10.1016/s0896-6273(01)00296-3] [Citation(s) in RCA: 384] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Rapid nerve impulse conduction depends on specialized membrane domains in myelinated nerve, the node of Ranvier, the paranode, and the myelinated internodal region. We report that GPI-linked contactin enables the formation of the paranodal septate-like axo-glial junctions in myelinated peripheral nerve. Contactin clusters at the paranodal axolemma during Schwann cell myelination. Ablation of contactin in mutant mice disrupts junctional attachment at the paranode and reduces nerve conduction velocity 3-fold. The mutation impedes intracellular transport and surface expression of Caspr and leaves NF155 on apposing paranodal myelin disengaged. The contactin mutation does not affect sodium channel clustering at the nodes of Ranvier but alters the location of the Shaker-type Kv1.1 and Kv1.2 potassium channels. Thus, contactin is a crucial part in the machinery that controls junctional attachment at the paranode and ultimately the physiology of myelinated nerve.
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MESH Headings
- Aging
- Animals
- Axons/physiology
- Cell Adhesion Molecules, Neuronal/deficiency
- Cell Adhesion Molecules, Neuronal/genetics
- Cell Adhesion Molecules, Neuronal/physiology
- Contactins
- Crosses, Genetic
- Gene Expression Regulation, Developmental
- Kv1.1 Potassium Channel
- Kv1.2 Potassium Channel
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microscopy, Electron
- Models, Neurological
- Nerve Fibers, Myelinated/physiology
- Nerve Fibers, Myelinated/ultrastructure
- Neuroglia/physiology
- Potassium Channels/physiology
- Potassium Channels, Voltage-Gated
- Ranvier's Nodes/physiology
- Ranvier's Nodes/ultrastructure
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Schwann Cells/physiology
- Sciatic Nerve/physiology
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Affiliation(s)
- M E Boyle
- Neurobiology Program, The Burnham Institute, La Jolla, CA 92037, USA
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44
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Abstract
On axonal surfaces that flank the node of Ranvier and in overlying glial paranodal loops, proteins are arranged within circumscribed microdomains that defy explanation by conventional biosynthetic mechanisms. We postulate that the constraint of proteins to these loci is accomplished in part by discriminative membrane-embedded molecular sieves and diffusion barriers, which serve to organize and redistribute proteins after delivery by vesicular transport to neural cell plasma membranes. One sieve likely comprises a moveable, macromolecular scaffold of axonal and glial cell-derived transmembrane adhesion molecules and their associated cytoplasmic binding partners, located at the ends of each elongating myelin internode; this sieve contributes to restricting the sodium channel complexes to the node. We also anticipate the existence of a passive paranodal diffusion barrier at the myelin/noncompact membrane border, which prohibits protein diffusion out of contiguous paranodal membranes.
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Affiliation(s)
- L Pedraza
- The Corinne Goldsmith Dickinson Center for Multiple Sclerosis, Department of Neurology, The Mount Sinai School of Medicine, 1425 Madison Avenue, New York, NY 10029, USA
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45
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Ogawa T, Hagihara K, Suzuki M, Yamaguchi Y. Brevican in the developing hippocampal fimbria: differential expression in myelinating oligodendrocytes and adult astrocytes suggests a dual role for brevican in central nervous system fiber tract development. J Comp Neurol 2001; 432:285-95. [PMID: 11246208 DOI: 10.1002/cne.1103] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Brevican is one of the most abundant extracellular matrix proteoglycans in the mammalian brain. We have previously shown that brevican produced by gray matter astrocytes constitutes a major component of perineuronal extracellular matrix in the adult brain. In this paper, we investigate the expression of brevican in the postnatal hippocampal fimbria to explore the role of the proteoglycan in central nervous system fiber tract development. We demonstrate that brevican is expressed by both oligodendrocytes and white matter astrocytes in the fimbria, but the expression of brevican in these two glial cell types is differently regulated during development. At P14, brevican immunoreactivity was observed throughout the fimbria, with particularly strong immunoreactivity in the developing interfascicular glial rows. In situ hybridization showed that oligodendrocytes in the glial rows strongly express brevican during the second and third postnatal weeks. Expression in oligodendrocytes was then down-regulated after P21. In the adult fimbria, no brevican expression was observed in oligodendrocytes. The time window of brevican expression coincides with the phase in which immature oligodendrocytes actively extend membrane processes and enwrap axon fibers. In contrast, the expression in astrocytes started around P21 as oligodendrocytes began to down-regulate the expression. In the adult fimbria, brevican expression was restricted to astrocytes. In situ hybridization with isoform-specific probes and RNase protection assays showed that the authentic, secreted form of brevican, not the glycosylphosphatidylinositol-anchored variant, is the predominant species expressed in the developing fimbria. Our results suggest that brevican plays a dual role in developing and adult fiber tracts.
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Affiliation(s)
- T Ogawa
- The Burnham Institute, La Jolla, California 92037, USA
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46
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Baumann N, Pham-Dinh D. Biology of oligodendrocyte and myelin in the mammalian central nervous system. Physiol Rev 2001; 81:871-927. [PMID: 11274346 DOI: 10.1152/physrev.2001.81.2.871] [Citation(s) in RCA: 1203] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Oligodendrocytes, the myelin-forming cells of the central nervous system (CNS), and astrocytes constitute macroglia. This review deals with the recent progress related to the origin and differentiation of the oligodendrocytes, their relationships to other neural cells, and functional neuroglial interactions under physiological conditions and in demyelinating diseases. One of the problems in studies of the CNS is to find components, i.e., markers, for the identification of the different cells, in intact tissues or cultures. In recent years, specific biochemical, immunological, and molecular markers have been identified. Many components specific to differentiating oligodendrocytes and to myelin are now available to aid their study. Transgenic mice and spontaneous mutants have led to a better understanding of the targets of specific dys- or demyelinating diseases. The best examples are the studies concerning the effects of the mutations affecting the most abundant protein in the central nervous myelin, the proteolipid protein, which lead to dysmyelinating diseases in animals and human (jimpy mutation and Pelizaeus-Merzbacher disease or spastic paraplegia, respectively). Oligodendrocytes, as astrocytes, are able to respond to changes in the cellular and extracellular environment, possibly in relation to a glial network. There is also a remarkable plasticity of the oligodendrocyte lineage, even in the adult with a certain potentiality for myelin repair after experimental demyelination or human diseases.
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Affiliation(s)
- N Baumann
- Institut National de la Santé et de la Recherche Médicale U. 495, Biology of Neuron-Glia Interactions, Salpêtrière Hospital, Paris, France.
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47
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Abstract
Myelinating Schwann cells control the number of neurofilaments and elevate the phosphorylation state of neurofilaments in the axon, eventually leading to the typical large axon caliber. Conversely, absence of myelin leads to lower amounts of neurofilaments, reduced phosphorylation levels, and smaller axon diameters. In addition, myelinating Schwann cells mediate the spacing of Na(+) channel clusters during development of the node of Ranvier. When axons are associated with mutant Schwann cells in inherited neuropathies, their calibers are reduced and their neurofilaments are less phosphorylated and more closely spaced. Also, axonal transport is reduced and axons degenerate at the distal ends of long nerves. Myelin-associated glycoprotein may mediate some aspects of Schwann cell-axon communication, but much remains to be learned about the molecular bases of Schwann cell-axon communication.
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Affiliation(s)
- R Martini
- Department of Neurology, Section of Developmental Neurobiology, University of Würzburg, Josef-Schneider-Strasse 11, D-97080 Würzburg, Germany.
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Contactin-associated protein (Caspr) and contactin form a complex that is targeted to the paranodal junctions during myelination. J Neurosci 2001. [PMID: 11069942 DOI: 10.1523/jneurosci.20-22-08354.2000] [Citation(s) in RCA: 173] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Specialized paranodal junctions form between the axon and the closely apposed paranodal loops of myelinating glia. They are interposed between sodium channels at the nodes of Ranvier and potassium channels in the juxtaparanodal regions; their precise function and molecular composition have been elusive. We previously reported that Caspr (contactin-associated protein) is a major axonal constituent of these junctions (Einheber et al., 1997). We now report that contactin colocalizes and forms a cis complex with Caspr in the paranodes and juxtamesaxon. These proteins coextract and coprecipitate from neurons, myelinating cultures, and myelin preparations enriched in junctional markers; they fractionate on sucrose gradients as a high-molecular-weight complex, suggesting that other proteins may also be associated with this complex. Neurons express two contactin isoforms that differ in their extent of glycosylation: a lower-molecular-weight phosphatidylinositol phospholipase C (PI-PLC)-resistant form is associated specifically with Caspr in the paranodes, whereas a higher-molecular-weight form of contactin, not associated with Caspr, is present in central nodes of Ranvier. These results suggest that the targeting of contactin to different axonal domains may be determined, in part, via its association with Caspr. Treatment of myelinating cocultures of Schwann cells and neurons with RPTPbeta-Fc, a soluble construct containing the carbonic anhydrase domain of the receptor protein tyrosine phosphatase beta (RPTPbeta), a potential glial receptor for contactin, blocks the localization of the Caspr/contactin complex to the paranodes. These results strongly suggest that a preformed complex of Caspr and contactin is targeted to the paranodal junctions via extracellular interactions with myelinating glia.
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Melendez-Vasquez CV, Rios JC, Zanazzi G, Lambert S, Bretscher A, Salzer JL. Nodes of Ranvier form in association with ezrin-radixin-moesin (ERM)-positive Schwann cell processes. Proc Natl Acad Sci U S A 2001; 98:1235-40. [PMID: 11158623 PMCID: PMC14738 DOI: 10.1073/pnas.98.3.1235] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the adult peripheral nerve, microvillous processes of myelinating Schwann cells project to the nodes of Ranvier; their composition and physiologic function have not been established. As the ezrin-radixin-moesin (ERM) proteins are expressed in the microvilli of many epithelial cells, we have examined the expression and distribution of these proteins in Schwann cells and neurons in vitro and in vivo. Cultured Schwann cells express high levels of all three proteins and the ezrin-binding protein 50, whereas neurons express much lower, although detectable, levels of radixin and moesin. Ezrin is specific for Schwann cells. All three ERM proteins are expressed predominantly at the membrane of cultured Schwann cells, notably in their microvilli. In vivo, the ERM proteins are concentrated strikingly in the nodal processes of myelinating Schwann cells. Because these processes are devoid of myelin proteins, they represent a unique compartment of the myelinating Schwann cell. During development, the ERM proteins become concentrated at the ends of Schwann cells before myelin basic protein expression, demonstrating that Schwann cells are polarized longitudinally at the onset of myelination. ERM-positive Schwann cell processes overlie and are associated closely with nascent nodes of Ranvier, identified by clusters of ankyrin G. Ankyrin accumulation at the node precedes that of Caspr at the paranodes and therefore does not depend on the presence of mature paranodal junctions. These results demonstrate that nodes of Ranvier in the peripheral nervous system form in contact with specialized processes of myelinating Schwann cells that are highly enriched in ERM proteins.
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Affiliation(s)
- C V Melendez-Vasquez
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
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50
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Ohara R, Yamakawa H, Nakayama M, Ohara O. Type II brain 4.1 (4.1B/KIAA0987), a member of the protein 4.1 family, is localized to neuronal paranodes. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2000; 85:41-52. [PMID: 11146105 DOI: 10.1016/s0169-328x(00)00233-3] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Histochemical analyses of type II brain 4.1/4.1B/KIAA0987, a member of the protein 4.1 family, were carried out in rat brain. In situ hybridization (ISH) showed that type II brain 4.1 mRNA is expressed in a variety of neuronal cells. In particular, type II brain 4.1 mRNA was actively transcribed in the cells of the mesencephalon and the brainstem, which have large myelinated nerve fibers. Expression of type II brain 4.1 mRNA was not observed at least in glial cells distributed in nerve fiber tracts. In immunohistochemical studies using anti-type II brain 4.1-specific antibody, the major immunosignals appeared as brilliant pairs of dots along nerve fibers. Such immunosignals were detected throughout the brain, but were highly concentrated in nerve fiber tracts. These data suggested that type II brain 4.1 is predominantly localized to neuronal paranodes. Detailed analysis concentrating on the nodal region indicated that type II brain 4.1 is present at the paranodal membrane but not in the axoplasm. Weaker type II brain 4.1-specific immunosignals were observed along the internodal membrane of myelinated axons and in the cytoplasm of some neuronal cells. Finally, comparative immunohistochemical studies using antibodies against the other three protein 4.1 family members, type I brain 4.1/4.1N/KIAA0338, erythroid type 4.1 (4.1R) and 4.1G, demonstrated that each of these proteins is distributed in a unique pattern in the cerebellum. Our results are the first to show that type II brain 4.1 is the only member of the protein 4.1 family localized to neuronal paranodes.
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Affiliation(s)
- R Ohara
- Department of Human Gene Research, Kazusa DNA Research Institute, Yana 1532-3, Kisarazu 292-0812, Japan.
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