1
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Scherer SS, Svaren J. Peripheral Nervous System (PNS) Myelin Diseases. Cold Spring Harb Perspect Biol 2024; 16:a041376. [PMID: 38253417 PMCID: PMC11065170 DOI: 10.1101/cshperspect.a041376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
This is a review of inherited and acquired causes of human demyelinating neuropathies and a subset of disorders that affect axon-Schwann cell interactions. Nearly all inherited demyelinating neuropathies are caused by mutations in genes that are expressed by myelinating Schwann cells, affecting diverse functions in a cell-autonomous manner. The most common acquired demyelinating neuropathies are Guillain-Barré syndrome and chronic, inflammatory demyelinating polyneuropathy, both of which are immune-mediated. An additional group of inherited and acquired disorders affect axon-Schwann cell interactions in the nodal region. Overall, these disorders affect the formation of myelin and its maintenance, with superimposed axonal loss that is clinically important.
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Affiliation(s)
- Steven S Scherer
- Department of Neurology, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - John Svaren
- Department of Comparative Biosciences, Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
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2
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Sert O, Ding X, Zhang C, Mi R, Hoke A, Rasband MN. Postsynaptic β1 spectrin maintains Na + channels at the neuromuscular junction. J Physiol 2024; 602:1127-1145. [PMID: 38441922 PMCID: PMC10942750 DOI: 10.1113/jp285894] [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: 11/01/2023] [Accepted: 02/13/2024] [Indexed: 03/16/2024] Open
Abstract
Spectrins function together with actin as obligatory subunits of the submembranous cytoskeleton. Spectrins maintain cell shape, resist mechanical forces, and stabilize ion channel and transporter protein complexes through binding to scaffolding proteins. Recently, pathogenic variants of SPTBN4 (β4 spectrin) were reported to cause both neuropathy and myopathy. Although the role of β4 spectrin in neurons is mostly understood, its function in skeletal muscle, another excitable tissue subject to large forces, is unknown. Here, using a muscle specific β4 spectrin conditional knockout mouse, we show that β4 spectrin does not contribute to muscle function. In addition, we show β4 spectrin is not present in muscle, indicating the previously reported myopathy associated with pathogenic SPTBN4 variants is neurogenic in origin. More broadly, we show that α2, β1 and β2 spectrins are found in skeletal muscle, with α2 and β1 spectrins being enriched at the postsynaptic neuromuscular junction (NMJ). Surprisingly, using muscle specific conditional knockout mice, we show that loss of α2 and β2 spectrins had no effect on muscle health, function or the enrichment of β1 spectrin at the NMJ. Muscle specific deletion of β1 spectrin also had no effect on muscle health, but, with increasing age, resulted in the loss of clustered NMJ Na+ channels. Together, our results suggest that muscle β1 spectrin functions independently of an associated α spectrin to maintain Na+ channel clustering at the postsynaptic NMJ. Furthermore, despite repeated exposure to strong forces and in contrast to neurons, muscles do not require spectrin cytoskeletons to maintain cell shape or integrity. KEY POINTS: The myopathy found in pathogenic human SPTBN4 variants (where SPTBN4 is the gene encoding β4 spectrin) is neurogenic in origin. β1 spectrin plays essential roles in maintaining the density of neuromuscular junction Nav1.4 Na+ channels. By contrast to the canonical view of spectrin organization and function, we show that β1 spectrin can function independently of an associated α spectrin. Despite the large mechanical forces experienced by muscle, we show that spectrins are not required for muscle cell integrity. This is in stark contrast to red blood cells and the axons of neurons.
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Affiliation(s)
- Ozlem Sert
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA 77030
| | - Xiaoyun Ding
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA 77030
| | - Chuansheng Zhang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA 77030
| | - Ruifa Mi
- Departments of Neurology and Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD 21205
| | - Ahmet Hoke
- Departments of Neurology and Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD 21205
| | - Matthew N. Rasband
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA 77030
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3
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Glomb O, Swaim G, Munoz LLancao P, Lovejoy C, Sutradhar S, Park J, Wu Y, Cason SE, Holzbaur ELF, Hammarlund M, Howard J, Ferguson SM, Gramlich MW, Yogev S. A kinesin-1 adaptor complex controls bimodal slow axonal transport of spectrin in Caenorhabditis elegans. Dev Cell 2023; 58:1847-1863.e12. [PMID: 37751746 PMCID: PMC10574138 DOI: 10.1016/j.devcel.2023.08.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 08/18/2023] [Accepted: 08/30/2023] [Indexed: 09/28/2023]
Abstract
An actin-spectrin lattice, the membrane periodic skeleton (MPS), protects axons from breakage. MPS integrity relies on spectrin delivery via slow axonal transport, a process that remains poorly understood. We designed a probe to visualize endogenous spectrin dynamics at single-axon resolution in vivo. Surprisingly, spectrin transport is bimodal, comprising fast runs and movements that are 100-fold slower than previously reported. Modeling and genetic analysis suggest that the two rates are independent, yet both require kinesin-1 and the coiled-coil proteins UNC-76/FEZ1 and UNC-69/SCOC, which we identify as spectrin-kinesin adaptors. Knockdown of either protein led to disrupted spectrin motility and reduced distal MPS, and UNC-76 overexpression instructed excessive transport of spectrin. Artificially linking spectrin to kinesin-1 drove robust motility but inefficient MPS assembly, whereas impairing MPS assembly led to excessive spectrin transport, suggesting a balance between transport and assembly. These results provide insight into slow axonal transport and MPS integrity.
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Affiliation(s)
- Oliver Glomb
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA
| | - Grace Swaim
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA; Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Pablo Munoz LLancao
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Christopher Lovejoy
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Sabyasachi Sutradhar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06510, USA
| | - Junhyun Park
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA
| | - Youjun Wu
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Sydney E Cason
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA; Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erika L F Holzbaur
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA; Pennsylvania Muscle Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Marc Hammarlund
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA; Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Jonathon Howard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06510, USA; Quantitative Biology Institute, Yale University, New Haven, CT 06510, USA
| | - Shawn M Ferguson
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA
| | | | - Shaul Yogev
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA.
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4
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Maor G, Dubreuil RR, Feany MB. α-synuclein promotes neuronal dysfunction and death by disrupting the binding of ankyrin to ß-spectrin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.02.543481. [PMID: 37333277 PMCID: PMC10274672 DOI: 10.1101/2023.06.02.543481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
α-synuclein plays a key role in the pathogenesis of Parkinson's disease and related disorders, but critical interacting partners and molecular mechanisms mediating neurotoxicity are incompletely understood. We show that α-synuclein binds directly to ß-spectrin. Using males and females in a Drosophila model of α-synuclein-related disorders we demonstrate that ß-spectrin is critical for α-synuclein neurotoxicity. Further, the ankyrin binding domain of ß-spectrin is required for α-synuclein binding and neurotoxicity. A key plasma membrane target of ankyrin, Na+/K+ ATPase, is mislocalized when human α-synuclein is expressed in Drosophila. Accordingly, membrane potential is depolarized in α-synuclein transgenic fly brains. We examine the same pathway in human neurons and find that Parkinson's disease patient-derived neurons with a triplication of the α-synuclein locus show disruption of the spectrin cytoskeleton, mislocalization of ankyrin and Na+/K+ ATPase, and membrane potential depolarization. Our findings define a specific molecular mechanism by which elevated levels of α-synuclein in Parkinson's disease and related α-synucleinopathies leads to neuronal dysfunction and death.
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Affiliation(s)
- Gali Maor
- Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Ronald R. Dubreuil
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Mel B. Feany
- Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD, 20815
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5
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Dolma S, Joshi A. The Node of Ranvier as an Interface for Axo-Glial Interactions: Perturbation of Axo-Glial Interactions in Various Neurological Disorders. J Neuroimmune Pharmacol 2023; 18:215-234. [PMID: 37285016 DOI: 10.1007/s11481-023-10072-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 05/19/2023] [Indexed: 06/08/2023]
Abstract
The action potential conduction along the axon is highly dependent on the healthy interactions between the axon and myelin-producing glial cells. Myelin, which facilitates action potential, is the protective insulation around the axon formed by Schwann cells and oligodendrocytes in the peripheral (PNS) and central nervous system (CNS), respectively. Myelin is a continuous structure with intermittent gaps called nodes of Ranvier, which are the sites enriched with ion channels, transmembrane, scaffolding, and cytoskeletal proteins. Decades-long extensive research has identified a comprehensive proteome with strictly regularized localization at the node of Ranvier. Concurrently, axon-glia interactions at the node of Ranvier have gathered significant attention as the pathophysiological targets for various neurodegenerative disorders. Numerous studies have shown the alterations in the axon-glia interactions culminating in neurological diseases. In this review, we have provided an update on the molecular composition of the node of Ranvier. Further, we have discussed in detail the consequences of disruption of axon-glia interactions during the pathogenesis of various CNS and PNS disorders.
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Affiliation(s)
- Sonam Dolma
- Department of Pharmacy, Birla Institute of Technology and Sciences- Pilani, Hyderabad campus, Telangana state, India
| | - Abhijeet Joshi
- Department of Pharmacy, Birla Institute of Technology and Sciences- Pilani, Hyderabad campus, Telangana state, India.
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6
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Appeltshauser L, Linke J, Heil HS, Karus C, Schenk J, Hemmen K, Sommer C, Doppler K, Heinze KG. Super-resolution imaging pinpoints the periodic ultrastructure at the human node of Ranvier and its disruption in patients with polyneuropathy. Neurobiol Dis 2023; 182:106139. [PMID: 37146836 DOI: 10.1016/j.nbd.2023.106139] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/13/2023] [Accepted: 04/25/2023] [Indexed: 05/07/2023] Open
Abstract
The node of Ranvier is the key element in saltatory conduction along myelinated axons, but its specific protein organization remains elusive in the human species. To shed light on nanoscale anatomy of the human node of Ranvier in health and disease, we assessed human nerve biopsies of patients with polyneuropathy by super-resolution fluorescence microscopy. We applied direct stochastic optical reconstruction microscopy (dSTORM) and supported our data by high-content confocal imaging combined with deep learning-based analysis. As a result, we revealed a ~ 190 nm periodic protein arrangement of cytoskeletal proteins and axoglial cell adhesion molecules in human peripheral nerves. In patients with polyneuropathy, periodic distances increased at the paranodal region of the node of Ranvier, both at the axonal cytoskeleton and at the axoglial junction. In-depth image analysis revealed a partial loss of proteins of the axoglial complex (Caspr-1, neurofascin-155) in combination with detachment from the cytoskeletal anchor protein ß2-spectrin. High content analysis showed that such paranodal disorganization occurred especially in acute and severe axonal neuropathy with ongoing Wallerian degeneration and related cytoskeletal damage. We provide nanoscale and protein-specific evidence for the prominent, but vulnerable role of the node of Ranvier for axonal integrity. Furthermore, we show that super-resolution imaging can identify, quantify and map elongated periodic protein distances and protein interaction in histopathological tissue samples. We thus introduce a promising tool for further translational applications of super resolution microscopy.
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Affiliation(s)
| | - Janis Linke
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany; Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Hannah S Heil
- Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany; Optical Cell Biology, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Christine Karus
- Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Joachim Schenk
- Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Katherina Hemmen
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Claudia Sommer
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Kathrin Doppler
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany.
| | - Katrin G Heinze
- Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany.
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7
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Lorenzo DN, Edwards RJ, Slavutsky AL. Spectrins: molecular organizers and targets of neurological disorders. Nat Rev Neurosci 2023; 24:195-212. [PMID: 36697767 PMCID: PMC10598481 DOI: 10.1038/s41583-022-00674-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/22/2022] [Indexed: 01/26/2023]
Abstract
Spectrins are cytoskeletal proteins that are expressed ubiquitously in the mammalian nervous system. Pathogenic variants in SPTAN1, SPTBN1, SPTBN2 and SPTBN4, four of the six genes encoding neuronal spectrins, cause neurological disorders. Despite their structural similarity and shared role as molecular organizers at the cell membrane, spectrins vary in expression, subcellular localization and specialization in neurons, and this variation partly underlies non-overlapping disease presentations across spectrinopathies. Here, we summarize recent progress in discerning the local and long-range organization and diverse functions of neuronal spectrins. We provide an overview of functional studies using mouse models, which, together with growing human genetic and clinical data, are helping to illuminate the aetiology of neurological spectrinopathies. These approaches are all critical on the path to plausible therapeutic solutions.
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Affiliation(s)
- Damaris N Lorenzo
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Reginald J Edwards
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Anastasia L Slavutsky
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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8
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Maor G, Dubreuil RR, Feany MB. α-Synuclein Promotes Neuronal Dysfunction and Death by Disrupting the Binding of Ankyrin to β-Spectrin. J Neurosci 2023; 43:1614-1626. [PMID: 36653193 PMCID: PMC10008058 DOI: 10.1523/jneurosci.1922-22.2022] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/30/2022] [Accepted: 12/08/2022] [Indexed: 01/20/2023] Open
Abstract
α-Synuclein plays a key role in the pathogenesis of Parkinson's disease and related disorders, but critical interacting partners and molecular mechanisms mediating neurotoxicity are incompletely understood. We show that α-synuclein binds directly to β-spectrin. Using males and females in a Drosophila model of α-synuclein-related disorders, we demonstrate that β-spectrin is critical for α-synuclein neurotoxicity. Further, the ankyrin binding domain of β-spectrin is required for α-synuclein binding and neurotoxicity. A key plasma membrane target of ankyrin, Na+/K+ ATPase, is mislocalized when human α-synuclein is expressed in Drosophila Accordingly, membrane potential is depolarized in α-synuclein transgenic fly brains. We examine the same pathway in human neurons and find that Parkinson's disease patient-derived neurons with a triplication of the α-synuclein locus show disruption of the spectrin cytoskeleton, mislocalization of ankyrin and Na+/K+ ATPase, and membrane potential depolarization. Our findings define a specific molecular mechanism by which elevated levels of α-synuclein in Parkinson's disease and related α-synucleinopathies lead to neuronal dysfunction and death.SIGNIFICANCE STATEMENT The small synaptic vesicle associate protein α-synuclein plays a critical role in the pathogenesis of Parkinson's disease and related disorders, but the disease-relevant binding partners of α-synuclein and proximate pathways critical for neurotoxicity require further definition. We show that α-synuclein binds directly to β-spectrin, a key cytoskeletal protein required for localization of plasma membrane proteins and maintenance of neuronal viability. Binding of α-synuclein to β-spectrin alters the organization of the spectrin-ankyrin complex, which is critical for localization and function of integral membrane proteins, including Na+/K+ ATPase. These finding outline a previously undescribed mechanism of α-synuclein neurotoxicity and thus suggest potential new therapeutic approaches in Parkinson's disease and related disorders.
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Affiliation(s)
- Gali Maor
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Ronald R Dubreuil
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Mel B Feany
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115
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9
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Alterations in Cerebellar Microtubule Cytoskeletal Network in a ValproicAcid-Induced Rat Model of Autism Spectrum Disorders. Biomedicines 2022; 10:biomedicines10123031. [PMID: 36551785 PMCID: PMC9776106 DOI: 10.3390/biomedicines10123031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/15/2022] [Accepted: 11/22/2022] [Indexed: 11/26/2022] Open
Abstract
Autism spectrum disorders (ASD) are neurodevelopmental diseases characterised by deficits in social communication, restricted interests, and repetitive behaviours. The growing body of evidence points to a role for cerebellar changes in ASD pathology. Some of the findings suggest that not only motor problems but also social deficits, repetitive behaviours, and mental inflexibility associated with ASD are connected with damage to the cerebellum. However, the understanding of this brain structure's functions in ASD pathology needs future investigations. Therefore, in this study, we generated a rodent model of ASD through a single prenatal administration of valproic acid (VPA) into pregnant rats, followed by cerebellar morphological studies of the offspring, focusing on the alterations of key cytoskeletal elements. The expression (Western blot) of α/β-tubulin and the major neuronal MT-associated proteins (MAP) such as MAP-Tau and MAP1B, MAP2, MAP6 (STOP) along with actin-crosslinking αII-spectrin and neurofilament light polypeptide (NF-L) was investigated. We found that maternal exposure to VPA induces a significant decrease in the protein levels of α/β-tubulin, MAP-Tau, MAP1B, MAP2, and αII-spectrin. Moreover, excessive MAP-Tau phosphorylation at (Ser396) along with key Tau-kinases activation was indicated. Immunohistochemical staining showed chromatolysis in the cerebellum of autistic-like rats and loss of Purkinje cells shedding light on one of the possible molecular mechanisms underpinning neuroplasticity alterations in the ASD brain.
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10
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MacKnight NJ, Dimos BA, Beavers KM, Muller EM, Brandt ME, Mydlarz LD. Disease resistance in coral is mediated by distinct adaptive and plastic gene expression profiles. SCIENCE ADVANCES 2022; 8:eabo6153. [PMID: 36179017 PMCID: PMC9524840 DOI: 10.1126/sciadv.abo6153] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Infectious diseases are an increasing threat to coral reefs, resulting in altered community structure and hindering the functional contributions of disease-susceptible species. We exposed seven reef-building coral species from the Caribbean to white plague disease and determined processes involved in (i) lesion progression, (ii) within-species gene expression plasticity, and (iii) expression-level adaptation among species that lead to differences in disease risk. Gene expression networks enriched in immune genes and cytoskeletal arrangement processes were correlated to lesion progression rates. Whether or not a coral developed a lesion was mediated by plasticity in genes involved in extracellular matrix maintenance, autophagy, and apoptosis, while resistant coral species had constitutively higher expression of intracellular protein trafficking. This study offers insight into the process involved in lesion progression and within- and between-species dynamics that lead to differences in disease risk that is evident on current Caribbean reefs.
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Affiliation(s)
- Nicholas J. MacKnight
- University of Texas at Arlington, 337 Life Science Building, Arlington, TX 76019, USA
| | - Bradford A. Dimos
- University of Texas at Arlington, 337 Life Science Building, Arlington, TX 76019, USA
| | - Kelsey M. Beavers
- University of Texas at Arlington, 337 Life Science Building, Arlington, TX 76019, USA
| | - Erinn M. Muller
- Mote Marine Laboratory, 1600 Ken Thompson Pkwy, Sarasota, FL 34236, USA
| | - Marilyn E. Brandt
- University of the Virgin Islands, 2 John Brewers Bay, St. Thomas, VI 00802, USA
| | - Laura D. Mydlarz
- University of Texas at Arlington, 337 Life Science Building, Arlington, TX 76019, USA
- Corresponding author.
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11
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Leterrier C, Pullarkat PA. Mechanical role of the submembrane spectrin scaffold in red blood cells and neurons. J Cell Sci 2022; 135:276327. [PMID: 35972759 DOI: 10.1242/jcs.259356] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Spectrins are large, evolutionarily well-conserved proteins that form highly organized scaffolds on the inner surface of eukaryotic cells. Their organization in different cell types or cellular compartments helps cells withstand mechanical challenges with unique strategies depending on the cell type. This Review discusses our understanding of the mechanical properties of spectrins, their very distinct organization in red blood cells and neurons as two examples, and the contribution of the scaffolds they form to the mechanical properties of these cells.
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Affiliation(s)
- Christophe Leterrier
- Aix Marseille Université, CNRS, INP UMR 7051, NeuroCyto, Marseille 13005, France
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12
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Elbaz B, Yang L, Vardy M, Isaac S, Rader BL, Kawaguchi R, Traka M, Woolf CJ, Renthal W, Popko B. Sensory neurons display cell-type-specific vulnerability to loss of neuron-glia interactions. Cell Rep 2022; 40:111130. [PMID: 35858549 PMCID: PMC9354470 DOI: 10.1016/j.celrep.2022.111130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/22/2021] [Accepted: 07/01/2022] [Indexed: 11/11/2022] Open
Abstract
Peripheral nervous system (PNS) injuries initiate transcriptional changes in glial cells and sensory neurons that promote axonal regeneration. While the factors that initiate the transcriptional changes in glial cells are well characterized, the full range of stimuli that initiate the response of sensory neurons remain elusive. Here, using a genetic model of glial cell ablation, we find that glial cell loss results in transient PNS demyelination without overt axonal loss. By profiling sensory ganglia at single-cell resolution, we show that glial cell loss induces a transcriptional injury response preferentially in proprioceptive and Aβ RA-LTMR neurons. The transcriptional response of sensory neurons to mechanical injury has been assumed to be a cell-autonomous response. By identifying a similar response in non-injured, demyelinated neurons, our study suggests that this represents a non-cell-autonomous transcriptional response of sensory neurons to glial cell loss and demyelination.
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Affiliation(s)
- Benayahu Elbaz
- Department of Neurology, Northwestern Feinberg School of Medicine, Chicago, IL, USA.
| | - Lite Yang
- Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, 60 Fenwood Road, Boston, MA 02115, USA
| | - Maia Vardy
- Department of Neurology, Northwestern Feinberg School of Medicine, Chicago, IL, USA
| | - Sara Isaac
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Braesen L Rader
- Department of Neurology, Northwestern Feinberg School of Medicine, Chicago, IL, USA
| | - Riki Kawaguchi
- Program in Neurogenetics, Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Maria Traka
- Department of Anatomy, College of Graduate Studies, Midwestern University, Downers Grove, IL, USA
| | - Clifford J Woolf
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA; F.M. Kirby Neurobiology Center, Boston Children's Hospital, 3 Blackfan Circle, Boston, MA 02115, USA
| | - William Renthal
- Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, 60 Fenwood Road, Boston, MA 02115, USA
| | - Brian Popko
- Department of Neurology, Northwestern Feinberg School of Medicine, Chicago, IL, USA.
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13
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Zhou R, Han B, Nowak R, Lu Y, Heller E, Xia C, Chishti AH, Fowler VM, Zhuang X. Proteomic and functional analyses of the periodic membrane skeleton in neurons. Nat Commun 2022; 13:3196. [PMID: 35680881 PMCID: PMC9184744 DOI: 10.1038/s41467-022-30720-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 05/09/2022] [Indexed: 12/29/2022] Open
Abstract
Actin, spectrin, and associated molecules form a membrane-associated periodic skeleton (MPS) in neurons. The molecular composition and functions of the MPS remain incompletely understood. Here, using co-immunoprecipitation and mass spectrometry, we identified hundreds of potential candidate MPS-interacting proteins that span diverse functional categories. We examined representative proteins in several of these categories using super-resolution imaging, including previously unknown MPS structural components, as well as motor proteins, cell adhesion molecules, ion channels, and signaling proteins, and observed periodic distributions characteristic of the MPS along the neurites for ~20 proteins. Genetic perturbations of the MPS and its interacting proteins further suggested functional roles of the MPS in axon-axon and axon-dendrite interactions and in axon diameter regulation, and implicated the involvement of MPS interactions with cell adhesion molecules and non-muscle myosin in these roles. These results provide insights into the interactome of the MPS and suggest previously unknown functions of the MPS in neurons.
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Affiliation(s)
- Ruobo Zhou
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA.
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA.
| | - Boran Han
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Roberta Nowak
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92307, USA
| | - Yunzhe Lu
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Evan Heller
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Chenglong Xia
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Athar H Chishti
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Velia M Fowler
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92307, USA
- Department of Biological Sciences, The University of Delaware, Newark, DE, 19716, USA
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA.
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14
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Eichel K, Shen K. The function of the axon initial segment in neuronal polarity. Dev Biol 2022; 489:47-54. [DOI: 10.1016/j.ydbio.2022.05.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 05/09/2022] [Accepted: 05/23/2022] [Indexed: 11/25/2022]
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15
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Luongo-Zink C, Ammons C, Al-Ramadhani R, Logan R, Ono K, Bhalla S, Kheder A, Marcus D, Drane D, Bearden D. Longitudinal neurodevelopmental profile of a pediatric patient with de novo SPTAN1, epilepsy, and left hippocampal sclerosis. Epilepsy Behav Rep 2022; 19:100550. [PMID: 35620303 PMCID: PMC9126767 DOI: 10.1016/j.ebr.2022.100550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 04/23/2022] [Accepted: 05/05/2022] [Indexed: 11/29/2022] Open
Abstract
We present the first longitudinal study of neuropsychological functioning in a pediatric patient with SPTAN1. To our knowledge we report the first case of SPTAN1 heterozygosity in a patient with MTLE due to HS. This case is the first to show that lisdexamfetamine dimesylate improved attention, behavior, and school performance in a patient with heterozygous SPTAN1 variant.
Pathogenic variants in SPTAN1 result in abnormal neurodevelopment but limited information is available on the spectrum of neurodevelopmental profiles associated with variations in this gene. We present novel data collected at two time points over a three-year period in a nine-year-old patient with heterozygous de novo SPTAN1 variant, drug-resistant epilepsy, and left hippocampal sclerosis. Across evaluations, our patient’s performance was highly variable, ranging from below age expectation to within age-expected range. The patient exhibited relative cognitive strengths at both time points on verbal-expressive tasks. Weaknesses were seen in her attention, executive function, psychomotor processing speed, fine motor, visual-motor integration, and social skills. Memory findings were consistent those associated with left hippocampal sclerosis. Evaluations resulted in diagnoses including attention deficit hyperactivity disorder and autism spectrum disorder.
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Affiliation(s)
- C. Luongo-Zink
- William James College, Newton, MA, USA
- Children’s Healthcare of Atlanta, Atlanta, GA, USA
| | - C. Ammons
- Children’s Healthcare of Atlanta, Atlanta, GA, USA
| | - R. Al-Ramadhani
- Children’s Healthcare of Atlanta, Atlanta, GA, USA
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
| | - R. Logan
- Children’s Healthcare of Atlanta, Atlanta, GA, USA
| | - K.E. Ono
- Children’s Healthcare of Atlanta, Atlanta, GA, USA
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
| | - S. Bhalla
- Children’s Healthcare of Atlanta, Atlanta, GA, USA
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
| | - A. Kheder
- Children’s Healthcare of Atlanta, Atlanta, GA, USA
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
| | - D.J. Marcus
- Children’s Healthcare of Atlanta, Atlanta, GA, USA
| | - D.L. Drane
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
- Department of Neurology, University of Washington School of Medicine, Seattle, WA, USA
| | - D.J. Bearden
- Children’s Healthcare of Atlanta, Atlanta, GA, USA
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
- Corresponding author at: Center for Advanced Pediatrics, Children’s Healthcare of Atlanta, 1400 Tullie Rd. NE, Ste. 430, Atlanta, GA 30329, USA.
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16
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Panganiban CH, Barth JL, Tan J, Noble KV, McClaskey CM, Howard BA, Jafri SH, Dias JW, Harris KC, Lang H. Two distinct types of nodes of Ranvier support auditory nerve function in the mouse cochlea. Glia 2021; 70:768-791. [DOI: 10.1002/glia.24138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 11/12/2021] [Accepted: 12/17/2021] [Indexed: 11/09/2022]
Affiliation(s)
- Clarisse H. Panganiban
- Department of Pathology and Laboratory Medicine Medical University of South Carolina Charleston South Carolina USA
- Wolfson Centre for Age‐Related Diseases King's College London London UK
| | - Jeremy L. Barth
- Department of Regenerative Medicine and Cell Biology Medical University of South Carolina Charleston South Carolina USA
| | - Junying Tan
- Department of Pathology and Laboratory Medicine Medical University of South Carolina Charleston South Carolina USA
| | - Kenyaria V. Noble
- Department of Pathology and Laboratory Medicine Medical University of South Carolina Charleston South Carolina USA
| | - Carolyn M. McClaskey
- Department of Otolaryngology & Head and Neck Surgery Medical University of South Carolina Charleston South Carolina USA
| | - Blake A. Howard
- Department of Pathology and Laboratory Medicine Medical University of South Carolina Charleston South Carolina USA
| | - Shabih H. Jafri
- Department of Pathology and Laboratory Medicine Medical University of South Carolina Charleston South Carolina USA
| | - James W. Dias
- Department of Otolaryngology & Head and Neck Surgery Medical University of South Carolina Charleston South Carolina USA
| | - Kelly C. Harris
- Department of Otolaryngology & Head and Neck Surgery Medical University of South Carolina Charleston South Carolina USA
| | - Hainan Lang
- Department of Pathology and Laboratory Medicine Medical University of South Carolina Charleston South Carolina USA
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17
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Abstract
Fluorescence imaging techniques play a pivotal role in our understanding of the nervous system. The emergence of various super-resolution microscopy methods and specialized fluorescent probes enables direct insight into neuronal structure and protein arrangements in cellular subcompartments with so far unmatched resolution. Super-resolving visualization techniques in neurons unveil a novel understanding of cytoskeletal composition, distribution, motility, and signaling of membrane proteins, subsynaptic structure and function, and neuron-glia interaction. Well-defined molecular targets in autoimmune and neurodegenerative disease models provide excellent starting points for in-depth investigation of disease pathophysiology using novel and innovative imaging methodology. Application of super-resolution microscopy in human brain samples and for testing clinical biomarkers is still in its infancy but opens new opportunities for translational research in neurology and neuroscience. In this review, we describe how super-resolving microscopy has improved our understanding of neuronal and brain function and dysfunction in the last two decades.
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Affiliation(s)
- Christian Werner
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Christian Geis
- Section Translational Neuroimmunology, Department of Neurology, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
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18
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SPTAN1 variants likely cause autosomal recessive complicated hereditary spastic paraplegia. J Hum Genet 2021; 67:165-168. [PMID: 34526651 DOI: 10.1038/s10038-021-00975-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/24/2021] [Accepted: 08/24/2021] [Indexed: 11/09/2022]
Abstract
Heterozygous mutations in SPTAN1 are associated with a broad phenotypical spectrum ranging from axonal neuropathy phenotypes to neurodevelopmental phenotypes with or without epilepsy. Recently, biallelic mutations in SPTAN1 were reported as a potential cause of autosomal recessive pure hereditary spastic paraplegia (HSP). However, no further HSP cases with biallelic SPTAN1 mutations have been reported. Herein, we report the clinical and genetic findings of a patient with complicated HSP likely caused by a novel homozygous SPTAN1 mutation. A patient with complicated HSP from a consanguineous family was recruited. The proband underwent detailed neurological examinations. Homozygosity mapping was performed in the proband and her healthy sister. Whole exome sequencing was performed in the proband. Our patient had early onset motor symptoms with upper motor neuron paralysis and intellectual disability, which is compatible with complicated HSP. Genetic analysis identified a rare homozygous missense mutation in SPTAN1 (c.4162A>G, p.I1388V), which was predicted to be deleterious by in silico tools. Her healthy parents and sister all carried the heterozygous mutation. Our results provided further support for the association of biallelic SPTAN1 variants with HSP and suggested that screening for the SPTAN1 gene should be considered not only in patients with pure HSP but also in patients with complicated HSP.
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19
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Fujitani M, Otani Y, Miyajima H. Pathophysiological Roles of Abnormal Axon Initial Segments in Neurodevelopmental Disorders. Cells 2021; 10:2110. [PMID: 34440880 PMCID: PMC8392614 DOI: 10.3390/cells10082110] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/13/2021] [Accepted: 08/15/2021] [Indexed: 11/17/2022] Open
Abstract
The 20-60 μm axon initial segment (AIS) is proximally located at the interface between the axon and cell body. AIS has characteristic molecular and structural properties regulated by the crucial protein, ankyrin-G. The AIS contains a high density of Na+ channels relative to the cell body, which allows low thresholds for the initiation of action potential (AP). Molecular and physiological studies have shown that the AIS is also a key domain for the control of neuronal excitability by homeostatic mechanisms. The AIS has high plasticity in normal developmental processes and pathological activities, such as injury, neurodegeneration, and neurodevelopmental disorders (NDDs). In the first half of this review, we provide an overview of the molecular, structural, and ion-channel characteristics of AIS, AIS regulation through axo-axonic synapses, and axo-glial interactions. In the second half, to understand the relationship between NDDs and AIS, we discuss the activity-dependent plasticity of AIS, the human mutation of AIS regulatory genes, and the pathophysiological role of an abnormal AIS in NDD model animals and patients. We propose that the AIS may provide a potentially valuable structural biomarker in response to abnormal network activity in vivo as well as a new treatment concept at the neural circuit level.
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Affiliation(s)
- Masashi Fujitani
- Department of Anatomy and Neuroscience, Faculty of Medicine, Shimane University, 89-1 Enya-cho, Izumo-shi 693-8501, Shimane, Japan; (Y.O.); (H.M.)
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20
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Quistgaard EM, Nissen JD, Hansen S, Nissen P. Mind the Gap: Molecular Architecture of the Axon Initial Segment - From Fold Prediction to a Mechanistic Model of Function? J Mol Biol 2021; 433:167176. [PMID: 34303720 DOI: 10.1016/j.jmb.2021.167176] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/14/2021] [Accepted: 07/14/2021] [Indexed: 11/28/2022]
Abstract
The axon initial segment (AIS) is a distinct neuronal domain, which is responsible for initiating action potentials, and therefore of key importance to neuronal signaling. To determine how it functions, it is necessary to establish which proteins reside there, how they are organized, and what the dynamic features are. Great strides have been made in recent years, and it is now clear that several AIS cytoskeletal and membrane proteins interact to form a higher-order periodic structure. Here we briefly describe AIS function, protein composition and molecular architecture, and discuss perspectives for future structural characterization, and if structure predictions will be able to model complex higher-order assemblies.
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Affiliation(s)
- Esben M Quistgaard
- DANDRITE - Nordic EMBL Partnership for Molecular Medicine, Aarhus University, Dept. Molecular Biology and Genetics, DK - 8000 Aarhus C, Denmark
| | - Josephine Dannersø Nissen
- DANDRITE - Nordic EMBL Partnership for Molecular Medicine, Aarhus University, Dept. Molecular Biology and Genetics, DK - 8000 Aarhus C, Denmark
| | - Sean Hansen
- DANDRITE - Nordic EMBL Partnership for Molecular Medicine, Aarhus University, Dept. Molecular Biology and Genetics, DK - 8000 Aarhus C, Denmark
| | - Poul Nissen
- DANDRITE - Nordic EMBL Partnership for Molecular Medicine, Aarhus University, Dept. Molecular Biology and Genetics, DK - 8000 Aarhus C, Denmark.
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21
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Stevens SR, Longley CM, Ogawa Y, Teliska LH, Arumanayagam AS, Nair S, Oses-Prieto JA, Burlingame AL, Cykowski MD, Xue M, Rasband MN. Ankyrin-R regulates fast-spiking interneuron excitability through perineuronal nets and Kv3.1b K + channels. eLife 2021; 10:66491. [PMID: 34180393 PMCID: PMC8257253 DOI: 10.7554/elife.66491] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 06/25/2021] [Indexed: 12/26/2022] Open
Abstract
Neuronal ankyrins cluster and link membrane proteins to the actin and spectrin-based cytoskeleton. Among the three vertebrate ankyrins, little is known about neuronal Ankyrin-R (AnkR). We report AnkR is highly enriched in Pv+ fast-spiking interneurons in mouse and human. We identify AnkR-associated protein complexes including cytoskeletal proteins, cell adhesion molecules (CAMs), and perineuronal nets (PNNs). We show that loss of AnkR from forebrain interneurons reduces and disrupts PNNs, decreases anxiety-like behaviors, and changes the intrinsic excitability and firing properties of Pv+ fast-spiking interneurons. These changes are accompanied by a dramatic reduction in Kv3.1b K+ channels. We identify a novel AnkR-binding motif in Kv3.1b, and show that AnkR is both necessary and sufficient for Kv3.1b membrane localization in interneurons and at nodes of Ranvier. Thus, AnkR regulates Pv+ fast-spiking interneuron function by organizing ion channels, CAMs, and PNNs, and linking these to the underlying β1 spectrin-based cytoskeleton.
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Affiliation(s)
- Sharon R Stevens
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Colleen M Longley
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, United States
| | - Yuki Ogawa
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Lindsay H Teliska
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | | | - Supna Nair
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, United States
| | - Juan A Oses-Prieto
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, United States
| | - Alma L Burlingame
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, United States
| | - Matthew D Cykowski
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, United States
| | - Mingshan Xue
- Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, United States.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Matthew N Rasband
- Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States
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22
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The Axonal Glycolytic Pathway Contributes to Sensory Axon Extension and Growth Cone Dynamics. J Neurosci 2021; 41:6637-6651. [PMID: 34252036 DOI: 10.1523/jneurosci.0321-21.2021] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/19/2021] [Accepted: 06/12/2021] [Indexed: 01/18/2023] Open
Abstract
Understanding the bioenergetics of axon extension and maintenance has wide ranging implications for neurodevelopment and disease states. Glycolysis is a pathway consisting of 10 enzymes and separated into preparatory and payoff phases, the latter producing ATP. Using embryonic chicken sensory neurons, we report that glycolytic enzymes are found through the axon and the growth cone. Pharmacological inhibition of glycolysis in the presence of NGF impairs axon extension and growth cone dynamics within minutes without affecting axon maintenance. Experiments using microfluidic chambers show that the effect of inhibiting glycolysis on axon extension is local along distal axons and can be reversed by promoting mitochondrial respiration. Knockdown of GAPDH simplifies growth cone morphology and is rescued by shRNA-resistant GAPDH expression. Rescue of GAPDH using KillerRed fused to GAPDH followed by localized chromophore-assisted light inactivation of KillerRed-GAPDH in distal axons halts growth cone dynamics. Considering filament polymerization requires ATP, inhibition of glycolysis results in a paradoxical increase in axonal actin filament levels. The effect on actin filaments is because of enzymes before GAPDH, the first enzyme in the payoff phase. In the absence of NGF, inhibition of glycolysis along distal axons results in axon degeneration independent of cell death. These data indicate that the glycolytic pathway is operative in distal axons and contributes to the rate of axon extension and growth cone dynamics in the presence of NGF and that, in the absence of NGF, the axonal glycolytic pathway is required for axon maintenance.SIGNIFICANCE STATEMENT Elucidation of the sources of ATP required for axon extension and maintenance has implications for understanding the mechanism of neuronal development and diseases of the nervous system. While recent work has emphasized the importance of mitochondrial oxidative phosphorylation, the role of the glycolytic pathway in axon morphogenesis and maintenance remains minimally understood. The data reveal that the glycolytic pathway is required for normal sensory axon extension in the presence of NGF, while in the absence of NGF the glycolytic pathway is required for axon maintenance. The results have implications for the understanding of the bioenergetics of axon morphogenesis and plasticity and indicate that NGF has protective effects on sensory axon maintenance in hypoglycemic states.
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23
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Deep transcriptome sequencing of subgenual anterior cingulate cortex reveals cross-diagnostic and diagnosis-specific RNA expression changes in major psychiatric disorders. Neuropsychopharmacology 2021; 46:1364-1372. [PMID: 33558674 PMCID: PMC8134494 DOI: 10.1038/s41386-020-00949-5] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 12/16/2020] [Accepted: 12/17/2020] [Indexed: 01/29/2023]
Abstract
Despite strong evidence of heritability and growing discovery of genetic markers for major mental illness, little is known about how gene expression in the brain differs across psychiatric diagnoses, or how known genetic risk factors shape these differences. Here we investigate expressed genes and gene transcripts in postmortem subgenual anterior cingulate cortex (sgACC), a key component of limbic circuits linked to mental illness. RNA obtained postmortem from 200 donors diagnosed with bipolar disorder, schizophrenia, major depression, or no psychiatric disorder was deeply sequenced to quantify expression of over 85,000 gene transcripts, many of which were rare. Case-control comparisons detected modest expression differences that were correlated across disorders. Case-case comparisons revealed greater expression differences, with some transcripts showing opposing patterns of expression between diagnostic groups, relative to controls. The ~250 rare transcripts that were differentially-expressed in one or more disorder groups were enriched for genes involved in synapse formation, cell junctions, and heterotrimeric G-protein complexes. Common genetic variants were associated with transcript expression (eQTL) or relative abundance of alternatively spliced transcripts (sQTL). Common genetic variants previously associated with disease risk were especially enriched for sQTLs, which together accounted for disproportionate fractions of diagnosis-specific heritability. Genetic risk factors that shape the brain transcriptome may contribute to diagnostic differences between broad classes of mental illness.
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24
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25
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Van de Vondel L, Baets J, Beijer D. Reply: De novo SPTAN1 mutation in axonal sensorimotor neuropathy and developmental disorder. Brain 2021; 143:e105. [PMID: 33207363 DOI: 10.1093/brain/awaa345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Liedewei Van de Vondel
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium
| | - Jonathan Baets
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium.,Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Belgium
| | - Danique Beijer
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium
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26
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Putting the axonal periodic scaffold in order. Curr Opin Neurobiol 2021; 69:33-40. [PMID: 33450534 DOI: 10.1016/j.conb.2020.12.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 01/01/2023]
Abstract
Neurons rely on a unique organization of their cytoskeleton to build, maintain and transform their extraordinarily intricate shapes. After decades of research on the neuronal cytoskeleton, it is exciting that novel assemblies are still discovered thanks to progress in cellular imaging methods. Indeed, super-resolution microscopy has revealed that axons are lined with a periodic scaffold of actin rings, spaced every 190nm by spectrins. Determining the architecture, composition, dynamics, and functions of this membrane-associated periodic scaffold is a current conceptual and technical challenge, as well as a very active area of research. This short review aims at summarizing the latest research on the axonal periodic scaffold, highlighting recent progress and open questions.
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27
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Morrow JS, Stankewich MC. The Spread of Spectrin in Ataxia and Neurodegenerative Disease. JOURNAL OF EXPERIMENTAL NEUROLOGY 2021; 2:131-139. [PMID: 34528024 PMCID: PMC8439443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Experimental and hereditary defects in the ubiquitous scaffolding proteins of the spectrin gene family cause an array of neuropathologies. Most recognized are ataxias caused by missense, deletions, or truncations in the SPTBN2 gene that encodes beta III spectrin. Such mutations disrupt the organization of post-synaptic receptors, their active transport through the secretory pathway, and the organization and dynamics of the actin-based neuronal skeleton. Similar mutations in SPTAN1 that encodes alpha II spectrin cause severe and usually lethal neurodevelopmental defects including one form of early infantile epileptic encephalopathy type 5 (West syndrome). Defects in these and other spectrins are implicated in degenerative and psychiatric conditions. In recent published work, we describe in mice a novel variant of alpha II spectrin that results in a progressive ataxia with widespread neurodegenerative change. The action of this variant is distinct, in that rather than disrupting a constitutive ligand-binding function of spectrin, the mutation alters its response to calcium and calmodulin-regulated signaling pathways including its response to calpain activation. As such, it represents a novel spectrinopathy that targets a key regulatory pathway where calcium and tyrosine kinase signals converge. Here we briefly discuss the various roles of spectrin in neuronal processes and calcium activated regulatory inputs that control its participation in neuronal growth, organization, and remodeling. We hypothesize that damage to the neuronal spectrin scaffold may be a common final pathway in many neurodegenerative disorders. Targeting the pathways that regulate spectrin function may thus offer novel avenues for therapeutic intervention.
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Affiliation(s)
- Jon S. Morrow
- Department of Pathology, Yale School of Medicine, New Haven, CT 06520, USA,Molecular & Cellular Developmental Biology, Yale University, New Haven, CT 06520, USA,Correspondence should be addressed to Jon S. Morrow; , Michael Stankewich;
| | - Michael C. Stankewich
- Department of Pathology, Yale School of Medicine, New Haven, CT 06520, USA,Correspondence should be addressed to Jon S. Morrow; , Michael Stankewich;
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28
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Abstract
The nodes of Ranvier have clustered Na+ and K+ channels necessary for rapid and efficient axonal action potential conduction. However, detailed mechanisms of channel clustering have only recently been identified: they include two independent axon-glia interactions that converge on distinct axonal cytoskeletons. Here, we discuss how glial cell adhesion molecules and the extracellular matrix molecules that bind them assemble combinations of ankyrins, spectrins and other cytoskeletal scaffolding proteins, which cluster ion channels. We present a detailed molecular model, incorporating these overlapping mechanisms, to explain how the nodes of Ranvier are assembled in both the peripheral and central nervous systems.
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29
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Ylikallio E, Ritari N, Sainio M, Toppila J, Kivirikko S, Tyynismaa H, Auranen M, Isohanni P. De novo SPTAN1 mutation in axonal sensorimotor neuropathy and developmental disorder. Brain 2020; 143:e104. [DOI: 10.1093/brain/awaa344] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Emil Ylikallio
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Niina Ritari
- Neuropsychology, New Children’s Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Markus Sainio
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Jussi Toppila
- Department of Clinical Neurophysiology, Medical Imaging Center, Helsinki University Central Hospital, Helsinki Finland
| | - Sirpa Kivirikko
- Department of Clinical Genetics, University of Helsinki, Helsinki University Hospital, Helsinki, Finland
- Department of Medical and Clinical Genetics, University of Helsinki, Finland
| | - Henna Tyynismaa
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Medical and Clinical Genetics, University of Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Mari Auranen
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Pirjo Isohanni
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Neurology, New Children’s Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
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30
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Wang C, Yang Y, Fu R, Zhu Y, Zhang H. Periodic subcellular structures undergo long-range synchronized reorganization during C. elegans epidermal development. J Cell Sci 2020; 133:jcs246793. [PMID: 33033182 PMCID: PMC10682509 DOI: 10.1242/jcs.246793] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 10/01/2020] [Indexed: 01/22/2023] Open
Abstract
Periodic pattern formation on the cellular and tissue scale is an important process and has been extensively studied. However, periodic pattern formation at the subcellular level still remains poorly understood. The C. elegans epidermis displays a highly ordered parallel stripe pattern as part of its subcellular structure, making it an ideal model to study the formation and reorganization of periodic patterns within cells. Here, we show that the initial formation of periodic striped patterns in the C. elegans epidermis is dependent on actin and spectrin, and requires the apical membrane attachment structures for maintenance. The periodic subcellular structures do not accommodate cell growth by continuously making new stripes. Instead, they increase the number of stripes by going through one round of uniform duplication, which is independent of the increasing epidermal length or the developmental cycles. This long-range synchronized reorganization of subcellular structures is achieved by physical links established by extracellular collagens together with extension forces generated from epidermal cell growth. Our studies uncover a novel strategy employed by evenly spaced and interlinked subcellular structures to maintain their integrity and equidistribution during cell growth and tissue development.
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Affiliation(s)
- Chunxia Wang
- Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou 215123, China
| | - Yuyan Yang
- Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou 215123, China
| | - Rong Fu
- Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou 215123, China
| | - Yi Zhu
- Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou 215123, China
| | - Huimin Zhang
- Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou 215123, China
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31
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Association of microtubules and axonal RNA transferred from myelinating Schwann cells in rat sciatic nerve. PLoS One 2020; 15:e0233651. [PMID: 32469980 PMCID: PMC7259579 DOI: 10.1371/journal.pone.0233651] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 05/09/2020] [Indexed: 01/19/2023] Open
Abstract
Transference of RNAs and ribosomes from Schwann cell-to-axon was demonstrated in normal and regenerating peripheral nerves. Previously, we have shown that RNAs transfer is dependent on F-actin cytoskeleton and Myosin Va. Here, we explored the contribution of microtubules to newly synthesized RNAs transport from Schwann cell nuclei up to nodal microvilli in sciatic nerves. Results using immunohistochemistry and quantitative confocal FRET analysis indicate that Schwann cell-derived RNAs co-localize with microtubules in Schwann cell cytoplasm. Additionally, transport of Schwann cell-derived RNAs is nocodazole and colchicine sensitive demonstrating its dependence on microtubule network integrity. Moreover, mRNAs codifying neuron-specific proteins are among Schwann cell newly synthesized RNAs population, and some of them are associated with KIF1B and KIF5B microtubules-based motors.
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32
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Liu CH, Seo R, Ho TSY, Stankewich M, Mohler PJ, Hund TJ, Noebels JL, Rasband MN. β spectrin-dependent and domain specific mechanisms for Na + channel clustering. eLife 2020; 9:e56629. [PMID: 32425157 PMCID: PMC7237202 DOI: 10.7554/elife.56629] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 05/07/2020] [Indexed: 12/23/2022] Open
Abstract
Previously, we showed that a hierarchy of spectrin cytoskeletal proteins maintains nodal Na+ channels (Liu et al., 2020). Here, using mice lacking β1, β4, or β1/β4 spectrins, we show this hierarchy does not function at axon initial segments (AIS). Although β1 spectrin, together with AnkyrinR (AnkR), compensates for loss of nodal β4 spectrin, it cannot compensate at AIS. We show AnkR lacks the domain necessary for AIS localization. Whereas loss of β4 spectrin causes motor impairment and disrupts AIS, loss of β1 spectrin has no discernable effect on central nervous system structure or function. However, mice lacking both neuronal β1 and β4 spectrin show exacerbated nervous system dysfunction compared to mice lacking β1 or β4 spectrin alone, including profound disruption of AIS Na+ channel clustering, progressive loss of nodal Na+ channels, and seizures. These results further define the important role of AIS and nodal spectrins for nervous system function.
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Affiliation(s)
- Cheng-Hsin Liu
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Program in Developmental Biology, Baylor College of MedicineHoustonUnited States
| | - Ryan Seo
- Department of Neurology, Baylor College of MedicineHoustonUnited States
| | - Tammy Szu-Yu Ho
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
| | | | - Peter J Mohler
- Department of Physiology and Cell Biology, The Ohio State UniversityColumbusUnited States
| | - Thomas J Hund
- Department of Biomedical Engineering, The Ohio State UniversityColumbusUnited States
| | - Jeffrey L Noebels
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Department of Neurology, Baylor College of MedicineHoustonUnited States
| | - Matthew N Rasband
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Program in Developmental Biology, Baylor College of MedicineHoustonUnited States
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33
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Beijer D, Deconinck T, De Bleecker JL, Dotti MT, Malandrini A, Urtizberea JA, Zulaica M, López de Munain A, Asselbergh B, De Jonghe P, Baets J. Nonsense mutations in alpha-II spectrin in three families with juvenile onset hereditary motor neuropathy. Brain 2020; 142:2605-2616. [PMID: 31332438 DOI: 10.1093/brain/awz216] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 04/25/2019] [Accepted: 05/28/2019] [Indexed: 01/09/2023] Open
Abstract
Distal hereditary motor neuropathies are a rare subgroup of inherited peripheral neuropathies hallmarked by a length-dependent axonal degeneration of lower motor neurons without significant involvement of sensory neurons. We identified patients with heterozygous nonsense mutations in the αII-spectrin gene, SPTAN1, in three separate dominant hereditary motor neuropathy families via next-generation sequencing. Variable penetrance was noted for these mutations in two of three families, and phenotype severity differs greatly between patients. The mutant mRNA containing nonsense mutations is broken down by nonsense-mediated decay and leads to reduced protein levels in patient cells. Previously, dominant-negative αII-spectrin gene mutations were described as causal in a spectrum of epilepsy phenotypes.
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Affiliation(s)
- Danique Beijer
- Neurogenetics Group, Center for Molecular Neurology, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium
| | - Tine Deconinck
- Neurogenetics Group, Center for Molecular Neurology, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium
| | | | - Maria Teresa Dotti
- Department of Medicine, Surgery and Neuroscience, University of Siena, Italy
| | | | | | - Miren Zulaica
- Neuroscience Area, Institute Biodonostia, Hospital Universitario Donostia, San Sebastian, Spain.,Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Institute Carlos III, Madrid, Spain
| | - Adolfo López de Munain
- Neuroscience Area, Institute Biodonostia, Hospital Universitario Donostia, San Sebastian, Spain.,Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Institute Carlos III, Madrid, Spain
| | - Bob Asselbergh
- VIB-UAntwerp Center for Molecular Neurology, University of Antwerp, Antwerp, Belgium
| | - Peter De Jonghe
- Neurogenetics Group, Center for Molecular Neurology, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium.,Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Belgium
| | - Jonathan Baets
- Neurogenetics Group, Center for Molecular Neurology, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium.,Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Belgium
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34
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Lorenzo DN. Cargo hold and delivery: Ankyrins, spectrins, and their functional patterning of neurons. Cytoskeleton (Hoboken) 2020; 77:129-148. [PMID: 32034889 DOI: 10.1002/cm.21602] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 01/12/2023]
Abstract
The highly polarized, typically very long, and nonmitotic nature of neurons present them with unique challenges in the maintenance of their homeostasis. This architectural complexity serves a rich and tightly controlled set of functions that enables their fast communication with neighboring cells and endows them with exquisite plasticity. The submembrane neuronal cytoskeleton occupies a pivotal position in orchestrating the structural patterning that determines local and long-range subcellular specialization, membrane dynamics, and a wide range of signaling events. At its center is the partnership between ankyrins and spectrins, which self-assemble with both remarkable long-range regularity and micro- and nanoscale specificity to precisely position and stabilize cell adhesion molecules, membrane transporters, ion channels, and other cytoskeletal proteins. To accomplish these generally conserved, but often functionally divergent and spatially diverse, roles these partners use a combinatorial program of a couple of dozens interacting family members, whose code is not fully unraveled. In a departure from their scaffolding roles, ankyrins and spectrins also enable the delivery of material to the plasma membrane by facilitating intracellular transport. Thus, it is unsurprising that deficits in ankyrins and spectrins underlie several neurodevelopmental, neurodegenerative, and psychiatric disorders. Here, I summarize key aspects of the biology of spectrins and ankyrins in the mammalian neuron and provide a snapshot of the latest advances in decoding their roles in the nervous system.
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Affiliation(s)
- Damaris N Lorenzo
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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35
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Liu CH, Stevens SR, Teliska LH, Stankewich M, Mohler PJ, Hund TJ, Rasband MN. Nodal β spectrins are required to maintain Na + channel clustering and axon integrity. eLife 2020; 9:52378. [PMID: 32052742 PMCID: PMC7018506 DOI: 10.7554/elife.52378] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 01/17/2020] [Indexed: 12/14/2022] Open
Abstract
Clustered ion channels at nodes of Ranvier are critical for fast action potential propagation in myelinated axons. Axon-glia interactions converge on ankyrin and spectrin cytoskeletal proteins to cluster nodal Na+ channels during development. However, how nodal ion channel clusters are maintained is poorly understood. Here, we generated mice lacking nodal spectrins in peripheral sensory neurons to uncouple their nodal functions from their axon initial segment functions. We demonstrate a hierarchy of nodal spectrins, where β4 spectrin is the primary spectrin and β1 spectrin can substitute; each is sufficient for proper node organization. Remarkably, mice lacking nodal β spectrins have normal nodal Na+ channel clustering during development, but progressively lose Na+ channels with increasing age. Loss of nodal spectrins is accompanied by an axon injury response and axon deformation. Thus, nodal spectrins are required to maintain nodal Na+ channel clusters and the structural integrity of axons.
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Affiliation(s)
- Cheng-Hsin Liu
- Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | - Sharon R Stevens
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Lindsay H Teliska
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | | | - Peter J Mohler
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, United States
| | - Thomas J Hund
- Biomedical Engineering, The Ohio State University, Columbus, United States
| | - Matthew N Rasband
- Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States
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36
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Niu F, Qian K, Qi H, Zhao Y, Jiang Y, Jia W, Sun M. CPCGI Reduces Gray and White Matter Injury by Upregulating Nrf2 Signaling and Suppressing Calpain Overactivation in a Rat Model of Controlled Cortical Impact. Neuropsychiatr Dis Treat 2020; 16:1929-1941. [PMID: 32904488 PMCID: PMC7455756 DOI: 10.2147/ndt.s266136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 07/28/2020] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Compound porcine cerebroside and ganglioside injection (CPCGI), which involves injection of a neurotrophic drug, has been widely used to treat certain brain disorders in the clinic; however, the detailed mechanism is unknown. This study investigated whether CPCGI protects the brain from trauma by stimulating antioxidative nuclear factor erythroid-2-related factor 2 (Nrf2) signaling and suppressing calpain overactivation in a rat model of controlled cortical impact (CCI). MATERIALS AND METHODS The rat model of CCI was used. Neurological deficits, contusion, and white matter damage were evaluated 3 days after CCI. Calpain activation, Nrf2 signaling and oxidative stress were determined 24 h after CCI. RESULTS CPCGI dose-dependently reduced neurological deficits, attenuated axonal and myelin sheath injury, and decreased contusion volume 3 days post-CCI. Moreover, CPCGI reduced calpain activity, and enhanced the cytosolic levels of calpastatin, αII-spectrin, microtubule-associated protein 2 (MAP2), neurofilament heavy chain (NF-H) and myelin basic protein (MBP) in traumatic tissues 24 h post-CCI. Furthermore, CPCGI reduced the levels of nuclear Kelch-like ECH-associated protein 1 (Keap1) and thioredoxin interacting protein (TXNIP); increased the levels of cytosolic Nrf2 and thioredoxin 1 (Trx 1) and nuclear Nrf2; increased the cytosolic and nuclear Nrf2/Keap1 and Trx 1/TXNIP ratios; enhanced the levels of heme oxygenase 1 (HO-1), glutathione (GSH), superoxide dismutase activity, and total antioxidative capacity; and reduced the levels of malondialdehyde in TBI tissues. CONCLUSION These data confirm the neuroprotective effect of CPCGI against gray and white matter damage due to CCI and suggest that activating Nrf2 signaling and alleviating oxidative stress-mediated calpain activation could be one mechanism by which CPCGI protects against brain trauma.
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Affiliation(s)
- Fei Niu
- Department of Neurotrauma, Beijing Key Laboratory of Central Nervous System Injury, Beijing Neurosurgical Institute, Capital Medical University, Beijing 100070, People's Republic of China
| | - Ke Qian
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, People's Republic of China
| | - Hongyan Qi
- Department of Acupuncture, Lianyungang TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Lianyungang City 222000, Jiangsu Province, People's Republic of China
| | - Yumei Zhao
- Department of Neuropharmacology, Beijing Key Laboratory of Central Nervous System Injury, Beijing Neurosurgical Institute, Capital Medical University, Beijing 100070, People's Republic of China
| | - Yingying Jiang
- Department of Neuropharmacology, Beijing Key Laboratory of Central Nervous System Injury, Beijing Neurosurgical Institute, Capital Medical University, Beijing 100070, People's Republic of China
| | - Wang Jia
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, People's Republic of China
| | - Ming Sun
- Department of Neuropharmacology, Beijing Key Laboratory of Central Nervous System Injury, Beijing Neurosurgical Institute, Capital Medical University, Beijing 100070, People's Republic of China
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37
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Leveille E, Estiar MA, Krohn L, Spiegelman D, Dionne-Laporte A, Dupré N, Trempe JF, Rouleau GA, Gan-Or Z. SPTAN1 variants as a potential cause for autosomal recessive hereditary spastic paraplegia. J Hum Genet 2019; 64:1145-1151. [DOI: 10.1038/s10038-019-0669-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/12/2019] [Accepted: 08/30/2019] [Indexed: 02/07/2023]
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38
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Lorenzo DN, Badea A, Zhou R, Mohler PJ, Zhuang X, Bennett V. βII-spectrin promotes mouse brain connectivity through stabilizing axonal plasma membranes and enabling axonal organelle transport. Proc Natl Acad Sci U S A 2019; 116:15686-15695. [PMID: 31209033 PMCID: PMC6681763 DOI: 10.1073/pnas.1820649116] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
βII-spectrin is the generally expressed member of the β-spectrin family of elongated polypeptides that form micrometer-scale networks associated with plasma membranes. We addressed in vivo functions of βII-spectrin in neurons by knockout of βII-spectrin in mouse neural progenitors. βII-spectrin deficiency caused severe defects in long-range axonal connectivity and axonal degeneration. βII-spectrin-null neurons exhibited reduced axon growth, loss of actin-spectrin-based periodic membrane skeleton, and impaired bidirectional axonal transport of synaptic cargo. We found that βII-spectrin associates with KIF3A, KIF5B, KIF1A, and dynactin, implicating spectrin in the coupling of motors and synaptic cargo. βII-spectrin required phosphoinositide lipid binding to promote axonal transport and restore axon growth. Knockout of ankyrin-B (AnkB), a βII-spectrin partner, primarily impaired retrograde organelle transport, while double knockout of βII-spectrin and AnkB nearly eliminated transport. Thus, βII-spectrin promotes both axon growth and axon stability through establishing the actin-spectrin-based membrane-associated periodic skeleton as well as enabling axonal transport of synaptic cargo.
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Affiliation(s)
- Damaris N Lorenzo
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599;
| | | | - Ruobo Zhou
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
- Department of Physics, Harvard University, Cambridge, MA 02138
| | - Peter J Mohler
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH 43210
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
- Department of Physics, Harvard University, Cambridge, MA 02138
| | - Vann Bennett
- Department of Biochemistry, Duke University, Durham, NC 27710
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39
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40
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Machnicka B, Grochowalska R, Bogusławska DM, Sikorski AF. The role of spectrin in cell adhesion and cell-cell contact. Exp Biol Med (Maywood) 2019; 244:1303-1312. [PMID: 31226892 DOI: 10.1177/1535370219859003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Spectrins are proteins that are responsible for many aspects of cell function and adaptation to changing environments. Primarily the spectrin-based membrane skeleton maintains cell membrane integrity and its mechanical properties, together with the cytoskeletal network a support cell shape. The occurrence of a variety of spectrin isoforms in diverse cellular environments indicates that it is a multifunctional protein involved in numerous physiological pathways. Participation of spectrin in cell–cell and cell–extracellular matrix adhesion and formation of dynamic plasma membrane protrusions and associated signaling events is a subject of interest for researchers in the fields of cell biology and molecular medicine. In this mini-review, we focus on data concerning the role of spectrins in cell surface activities such as adhesion, cell–cell contact, and invadosome formation. We discuss data on different adhesion proteins that directly or indirectly interact with spectrin repeats. New findings support the involvement of spectrin in cell adhesion and spreading, formation of lamellipodia, and also the participation in morphogenetic processes, such as eye development, oogenesis, and angiogenesis. Here, we review the role of spectrin in cell adhesion and cell–cell contact.Impact statementThis article reviews properties of spectrins as a group of proteins involved in cell surface activities such as, adhesion and cell–cell contact, and their contribution to morphogenesis. We show a new area of research and discuss the involvement of spectrin in regulation of cell–cell contact leading to immunological synapse formation and in shaping synapse architecture during myoblast fusion. Data indicate involvement of spectrins in adhesion and cell–cell or cell–extracellular matrix interactions and therefore in signaling pathways. There is evidence of spectrin’s contribution to the processes of morphogenesis which are connected to its interactions with adhesion molecules, membrane proteins (and perhaps lipids), and actin. Our aim was to highlight the essential role of spectrin in cell–cell contact and cell adhesion.
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Affiliation(s)
- Beata Machnicka
- Department of Biochemistry and Bioinformatics, Faculty of Biological Sciences, University of Zielona Góra, Zielona Góra 65-516, Poland
| | - Renata Grochowalska
- Department of Biochemistry and Bioinformatics, Faculty of Biological Sciences, University of Zielona Góra, Zielona Góra 65-516, Poland
| | - Dżamila M Bogusławska
- Department of Biochemistry and Bioinformatics, Faculty of Biological Sciences, University of Zielona Góra, Zielona Góra 65-516, Poland
| | - Aleksander F Sikorski
- Department of Cytobiochemistry, Faculty of Biotechnology, University of Wrocław, Wrocław 50-383, Poland
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41
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Lubbers ER, Murphy NP, Musa H, Huang CYM, Gupta R, Price MV, Han M, Daoud G, Gratz D, El Refaey M, Xu X, Hoeflinger NK, Friel EL, Lancione P, Wallace MJ, Cavus O, Simmons SL, Williams JL, Skaf M, Koenig SN, Janssen PML, Rasband MN, Hund TJ, Mohler PJ. Defining new mechanistic roles for αII spectrin in cardiac function. J Biol Chem 2019; 294:9576-9591. [PMID: 31064843 PMCID: PMC6579463 DOI: 10.1074/jbc.ra119.007714] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/22/2019] [Indexed: 01/04/2023] Open
Abstract
Spectrins are cytoskeletal proteins essential for membrane biogenesis and regulation and serve critical roles in protein targeting and cellular signaling. αII spectrin (SPTAN1) is one of two α spectrin genes and αII spectrin dysfunction is linked to alterations in axon initial segment formation, cortical lamination, and neuronal excitability. Furthermore, human αII spectrin loss-of-function variants cause neurological disease. As global αII spectrin knockout mice are embryonic lethal, the in vivo roles of αII spectrin in adult heart are unknown and untested. Here, based on pronounced alterations in αII spectrin regulation in human heart failure we tested the in vivo roles of αII spectrin in the vertebrate heart. We created a mouse model of cardiomyocyte-selective αII spectrin-deficiency (cKO) and used this model to define the roles of αII spectrin in cardiac function. αII spectrin cKO mice displayed significant structural, cellular, and electrical phenotypes that resulted in accelerated structural remodeling, fibrosis, arrhythmia, and mortality in response to stress. At the molecular level, we demonstrate that αII spectrin plays a nodal role for global cardiac spectrin regulation, as αII spectrin cKO hearts exhibited remodeling of αI spectrin and altered β-spectrin expression and localization. At the cellular level, αII spectrin deficiency resulted in altered expression, targeting, and regulation of cardiac ion channels NaV1.5 and KV4.3. In summary, our findings define critical and unexpected roles for the multifunctional αII spectrin protein in the heart. Furthermore, our work provides a new in vivo animal model to study the roles of αII spectrin in the cardiomyocyte.
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Affiliation(s)
- Ellen R Lubbers
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
- Medical Scientist Training Program
- the Departments of Physiology and Cell Biology and
| | - Nathaniel P Murphy
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
- Medical Scientist Training Program
- the Departments of Physiology and Cell Biology and
| | - Hassan Musa
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Claire Yu-Mei Huang
- the Department of Neuroscience and Integrative Molecular and Biomedical Sciences Graduate Program, Baylor College of Medicine, Houston, Texas 77030, and
| | - Rohan Gupta
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Morgan V Price
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Mei Han
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Georges Daoud
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Daniel Gratz
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
- the Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio 432310
| | - Mona El Refaey
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Xianyao Xu
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Nicole K Hoeflinger
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Emma L Friel
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Peter Lancione
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Michael J Wallace
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Omer Cavus
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Samantha L Simmons
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Jordan L Williams
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Michel Skaf
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Sara N Koenig
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
| | - Paul M L Janssen
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
- the Departments of Physiology and Cell Biology and
- Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University College of Medicine and Wexner Medical Center, Columbus, Ohio 432310
| | - Matthew N Rasband
- the Department of Neuroscience and Integrative Molecular and Biomedical Sciences Graduate Program, Baylor College of Medicine, Houston, Texas 77030, and
| | - Thomas J Hund
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia
- the Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio 432310
- Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University College of Medicine and Wexner Medical Center, Columbus, Ohio 432310
| | - Peter J Mohler
- From the Dorothy M. Davis Heart and Lung Research Institute and Frick Center for Heart Failure and Arrhythmia,
- the Departments of Physiology and Cell Biology and
- Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University College of Medicine and Wexner Medical Center, Columbus, Ohio 432310
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42
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Liu CH, Rasband MN. Axonal Spectrins: Nanoscale Organization, Functional Domains and Spectrinopathies. Front Cell Neurosci 2019; 13:234. [PMID: 31191255 PMCID: PMC6546920 DOI: 10.3389/fncel.2019.00234] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 05/09/2019] [Indexed: 11/13/2022] Open
Abstract
Spectrin cytoskeletons are found in all metazoan cells, and their physical interactions between actin and ankyrins establish a meshwork that provides cellular structural integrity. With advanced super-resolution microscopy, the intricate spatial organization and associated functional properties of these cytoskeletons can now be analyzed with unprecedented clarity. Long neuronal processes like peripheral sensory and motor axons may be subject to intense mechanical forces including bending, stretching, and torsion. The spectrin-based cytoskeleton is essential to protect axons against these mechanical stresses. Additionally, spectrins are critical for the assembly and maintenance of axonal excitable domains including the axon initial segment and the nodes of Ranvier (NoR). These sites facilitate rapid and efficient action potential initiation and propagation in the nervous system. Recent studies revealed that pathogenic spectrin variants and diseases that protealyze and breakdown spectrins are associated with congenital neurological disorders and nervous system injury. Here, we review recent studies of spectrins in the nervous system and focus on their functions in axonal health and disease.
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Affiliation(s)
- Cheng-Hsin Liu
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, United States
| | - Matthew Neil Rasband
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
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Wang G, Simon DJ, Wu Z, Belsky DM, Heller E, O'Rourke MK, Hertz NT, Molina H, Zhong G, Tessier-Lavigne M, Zhuang X. Structural plasticity of actin-spectrin membrane skeleton and functional role of actin and spectrin in axon degeneration. eLife 2019; 8:e38730. [PMID: 31042147 PMCID: PMC6494423 DOI: 10.7554/elife.38730] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 03/30/2019] [Indexed: 01/08/2023] Open
Abstract
Axon degeneration sculpts neuronal connectivity patterns during development and is an early hallmark of several adult-onset neurodegenerative disorders. Substantial progress has been made in identifying effector mechanisms driving axon fragmentation, but less is known about the upstream signaling pathways that initiate this process. Here, we investigate the behavior of the actin-spectrin-based Membrane-associated Periodic Skeleton (MPS), and effects of actin and spectrin manipulations in sensory axon degeneration. We show that trophic deprivation (TD) of mouse sensory neurons causes a rapid disassembly of the axonal MPS, which occurs prior to protein loss and independently of caspase activation. Actin destabilization initiates TD-related retrograde signaling needed for degeneration; actin stabilization prevents MPS disassembly and retrograde signaling during TD. Depletion of βII-spectrin, a key component of the MPS, suppresses retrograde signaling and protects axons against degeneration. These data demonstrate structural plasticity of the MPS and suggest its potential role in early steps of axon degeneration.
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Affiliation(s)
- Guiping Wang
- Department of Chemistry and Chemical BiologyHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
- Department of PhysicsHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
| | - David J Simon
- Laboratory of Brain Development and RepairThe Rockefeller UniversityNew YorkUnited States
- Department of BiologyStanford UniversityStanfordUnited States
| | - Zhuhao Wu
- Laboratory of Brain Development and RepairThe Rockefeller UniversityNew YorkUnited States
| | - Deanna M Belsky
- Department of BiologyStanford UniversityStanfordUnited States
| | - Evan Heller
- Department of Chemistry and Chemical BiologyHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
- Department of PhysicsHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
| | | | - Nicholas T Hertz
- Laboratory of Brain Development and RepairThe Rockefeller UniversityNew YorkUnited States
- Department of BiologyStanford UniversityStanfordUnited States
| | - Henrik Molina
- Proteomics Resource CenterThe Rockefeller UniversityNew YorkUnited States
| | - Guisheng Zhong
- Department of Chemistry and Chemical BiologyHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
- Department of PhysicsHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
| | - Marc Tessier-Lavigne
- Laboratory of Brain Development and RepairThe Rockefeller UniversityNew YorkUnited States
- Department of BiologyStanford UniversityStanfordUnited States
| | - Xiaowei Zhuang
- Department of Chemistry and Chemical BiologyHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
- Department of PhysicsHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
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Nodal Dynamics after In Vivo Rescue of βIV Spectrin Expression. J Neurosci 2019; 39:15-17. [PMID: 30602540 DOI: 10.1523/jneurosci.2149-18.2018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 10/23/2018] [Accepted: 10/27/2018] [Indexed: 11/21/2022] Open
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Yermakov LM, Hong LA, Drouet DE, Griggs RB, Susuki K. Functional Domains in Myelinated Axons. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1190:65-83. [PMID: 31760639 DOI: 10.1007/978-981-32-9636-7_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Propagation of action potentials along axons is optimized through interactions between neurons and myelinating glial cells. Myelination drives division of the axons into distinct molecular domains including nodes of Ranvier. The high density of voltage-gated sodium channels at nodes generates action potentials allowing for rapid and efficient saltatory nerve conduction. At paranodes flanking both sides of the nodes, myelinating glial cells interact with axons, forming junctions that are essential for node formation and maintenance. Recent studies indicate that the disruption of these specialized axonal domains is involved in the pathophysiology of various neurological diseases. Loss of paranodal axoglial junctions due to genetic mutations or autoimmune attack against the paranodal proteins leads to nerve conduction failure and neurological symptoms. Breakdown of nodal and paranodal proteins by calpains, the calcium-dependent cysteine proteases, may be a common mechanism involved in various nervous system diseases and injuries. This chapter reviews recent progress in neurobiology and pathophysiology of specialized axonal domains along myelinated nerve fibers.
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Affiliation(s)
- Leonid M Yermakov
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA
| | - Lulu A Hong
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA
| | - Domenica E Drouet
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA
| | - Ryan B Griggs
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA
| | - Keiichiro Susuki
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA.
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Sigal YM, Zhou R, Zhuang X. Visualizing and discovering cellular structures with super-resolution microscopy. Science 2018; 361:880-887. [PMID: 30166485 DOI: 10.1126/science.aau1044] [Citation(s) in RCA: 340] [Impact Index Per Article: 56.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Super-resolution microscopy has overcome a long-held resolution barrier-the diffraction limit-in light microscopy and enabled visualization of previously invisible molecular details in biological systems. Since their conception, super-resolution imaging methods have continually evolved and can now be used to image cellular structures in three dimensions, multiple colors, and living systems with nanometer-scale resolution. These methods have been applied to answer questions involving the organization, interaction, stoichiometry, and dynamics of individual molecular building blocks and their integration into functional machineries in cells and tissues. In this Review, we provide an overview of super-resolution methods, their state-of-the-art capabilities, and their constantly expanding applications to biology, with a focus on the latter. We will also describe the current technical challenges and future advances anticipated in super-resolution imaging.
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Affiliation(s)
- Yaron M Sigal
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Ruobo Zhou
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Department of Physics, Harvard University, Cambridge, MA 02138, USA.
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Experimental Traumatic Brain Injury Identifies Distinct Early and Late Phase Axonal Conduction Deficits of White Matter Pathophysiology, and Reveals Intervening Recovery. J Neurosci 2018; 38:8723-8736. [PMID: 30143572 PMCID: PMC6181309 DOI: 10.1523/jneurosci.0819-18.2018] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/15/2018] [Accepted: 07/10/2018] [Indexed: 01/26/2023] Open
Abstract
Traumatic brain injury (TBI) patients often exhibit slowed information processing speed that can underlie diverse symptoms. Processing speed depends on neural circuit function at synapses, in the soma, and along axons. Long axons in white matter (WM) tracts are particularly vulnerable to TBI. We hypothesized that disrupted axon–myelin interactions that slow or block action potential conduction in WM tracts may contribute to slowed processing speed after TBI. Concussive TBI in male/female mice was used to produce traumatic axonal injury in the corpus callosum (CC), similar to WM pathology in human TBI cases. Compound action potential velocity was slowed along myelinated axons at 3 d after TBI with partial recovery by 2 weeks, suggesting early demyelination followed by remyelination. Ultrastructurally, dispersed demyelinated axons and disorganized myelin attachment to axons at paranodes were apparent within CC regions exhibiting traumatic axonal injury. Action potential conduction is exquisitely sensitive to paranode abnormalities. Molecular identification of paranodes and nodes of Ranvier detected asymmetrical paranode pairs and abnormal heminodes after TBI. Fluorescent labeling of oligodendrocyte progenitors in NG2CreER;mTmG mice showed increased synthesis of new membranes extended along axons to paranodes, indicating remyelination after TBI. At later times after TBI, an overall loss of conducting axons was observed at 6 weeks followed by CC atrophy at 8 weeks. These studies identify a progression of both myelinated axon conduction deficits and axon–myelin pathology in the CC, implicating WM injury in impaired information processing at early and late phases after TBI. Furthermore, the intervening recovery reveals a potential therapeutic window. SIGNIFICANCE STATEMENT Traumatic brain injury (TBI) is a major global health concern. Across the spectrum of TBI severities, impaired information processing can contribute to diverse functional deficits that underlie persistent symptoms. We used experimental TBI to exploit technical advantages in mice while modeling traumatic axonal injury in white matter tracts, which is a key pathological feature of human TBI. A combination of approaches revealed slowed and failed signal conduction along with damage to the structure and molecular composition of myelinated axons in the white matter after TBI. An early regenerative response was not sustained yet reveals a potential time window for intervention. These insights into white matter abnormalities underlying axon conduction deficits can inform strategies to improve treatment options for TBI patients.
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Glial βII Spectrin Contributes to Paranode Formation and Maintenance. J Neurosci 2018; 38:6063-6075. [PMID: 29853631 DOI: 10.1523/jneurosci.3647-17.2018] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 04/24/2018] [Accepted: 05/14/2018] [Indexed: 12/18/2022] Open
Abstract
Action potential conduction along myelinated axons depends on high densities of voltage-gated Na+ channels at the nodes of Ranvier. Flanking each node, paranodal junctions (paranodes) are formed between axons and Schwann cells in the peripheral nervous system (PNS) or oligodendrocytes in the CNS. Paranodal junctions contribute to both node assembly and maintenance. Despite their importance, the molecular mechanisms responsible for paranode assembly and maintenance remain poorly understood. βII spectrin is expressed in diverse cells and is an essential part of the submembranous cytoskeleton. Here, we show that Schwann cell βII spectrin is highly enriched at paranodes. To elucidate the roles of glial βII spectrin, we generated mutant mice lacking βII spectrin in myelinating glial cells by crossing mice with a floxed allele of Sptbn1 with Cnp-Cre mice, and analyzed both male and female mice. Juvenile (4 weeks) and middle-aged (60 weeks) mutant mice showed reduced grip strength and sciatic nerve conduction slowing, whereas no phenotype was observed between 8 and 24 weeks of age. Consistent with these findings, immunofluorescence microscopy revealed disorganized paranodes in the PNS and CNS of both postnatal day 13 and middle-aged mutant mice, but not in young adult mutant mice. Electron microscopy confirmed partial loss of transverse bands at the paranodal axoglial junction in the middle-aged mutant mice in both the PNS and CNS. These findings demonstrate that a spectrin-based cytoskeleton in myelinating glia contributes to formation and maintenance of paranodal junctions.SIGNIFICANCE STATEMENT Myelinating glia form paranodal axoglial junctions that flank both sides of the nodes of Ranvier. These junctions contribute to node formation and maintenance and are essential for proper nervous system function. We found that a submembranous spectrin cytoskeleton is highly enriched at paranodes in Schwann cells. Ablation of βII spectrin in myelinating glial cells disrupted the paranodal cell adhesion complex in both peripheral and CNSs, resulting in muscle weakness and sciatic nerve conduction slowing in juvenile and middle-aged mice. Our data show that a spectrin-based submembranous cytoskeleton in myelinating glia plays important roles in paranode formation and maintenance.
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Papandréou MJ, Leterrier C. The functional architecture of axonal actin. Mol Cell Neurosci 2018; 91:151-159. [PMID: 29758267 DOI: 10.1016/j.mcn.2018.05.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 05/10/2018] [Accepted: 05/11/2018] [Indexed: 11/17/2022] Open
Abstract
The cytoskeleton builds and supports the complex architecture of neurons. It orchestrates the specification, growth, and compartmentation of the axon: axon initial segment, axonal shaft, presynapses. The cytoskeleton must then maintain this intricate architecture for the whole life of its host, but also drive its adaptation to new network demands and changing physiological conditions. Microtubules are readily visible inside axon shafts by electron microscopy, whereas axonal actin study has long been focused on dynamic structures of the axon such as growth cones. Super-resolution microscopy and live-cell imaging have recently revealed new actin-based structures in mature axons: rings, hotspots and trails. This has caused renewed interest for axonal actin, with efforts underway to understand the precise organization and cellular functions of these assemblies. Actin is also present in presynapses, where its arrangement is still poorly defined, and its functions vigorously debated. Here we review the organization of axonal actin, focusing on recent advances and current questions in this rejuvenated field.
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Huang CYM, Rasband MN. Axon initial segments: structure, function, and disease. Ann N Y Acad Sci 2018; 1420:46-61. [PMID: 29749636 DOI: 10.1111/nyas.13718] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 03/13/2018] [Accepted: 03/17/2018] [Indexed: 11/28/2022]
Abstract
The axon initial segment (AIS) is located at the proximal axon and is the site of action potential initiation. This reflects the high density of ion channels found at the AIS. Adaptive changes to the location and length of the AIS can fine-tune the excitability of neurons and modulate plasticity in response to activity. The AIS plays an important role in maintaining neuronal polarity by regulating the trafficking and distribution of proteins that function in somatodendritic or axonal compartments of the neuron. In this review, we provide an overview of the AIS cytoarchitecture, mechanism of assembly, and recent studies revealing mechanisms of differential transport at the AIS that maintain axon and dendrite identities. We further discuss how genetic mutations in AIS components (i.e., ankyrins, ion channels, and spectrins) and injuries may cause neurological disorders.
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Affiliation(s)
| | - Matthew N Rasband
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
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