1
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Hilton BJ, Husch A, Schaffran B, Lin TC, Burnside ER, Dupraz S, Schelski M, Kim J, Müller JA, Schoch S, Imig C, Brose N, Bradke F. An active vesicle priming machinery suppresses axon regeneration upon adult CNS injury. Neuron 2022; 110:51-69.e7. [PMID: 34706221 PMCID: PMC8730507 DOI: 10.1016/j.neuron.2021.10.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/03/2021] [Accepted: 10/01/2021] [Indexed: 12/16/2022]
Abstract
Axons in the adult mammalian central nervous system fail to regenerate after spinal cord injury. Neurons lose their capacity to regenerate during development, but the intracellular processes underlying this loss are unclear. We found that critical components of the presynaptic active zone prevent axon regeneration in adult mice. Transcriptomic analysis combined with live-cell imaging revealed that adult primary sensory neurons downregulate molecular constituents of the synapse as they acquire the ability to rapidly grow their axons. Pharmacogenetic reduction of neuronal excitability stimulated axon regeneration after adult spinal cord injury. Genetic gain- and loss-of-function experiments uncovered that essential synaptic vesicle priming proteins of the presynaptic active zone, but not clostridial-toxin-sensitive VAMP-family SNARE proteins, inhibit axon regeneration. Systemic administration of Baclofen reduced voltage-dependent Ca2+ influx in primary sensory neurons and promoted their regeneration after spinal cord injury. These findings indicate that functional presynaptic active zones constitute a major barrier to axon regeneration.
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Affiliation(s)
- Brett J Hilton
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Andreas Husch
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Barbara Schaffran
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Tien-Chen Lin
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Emily R Burnside
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Sebastian Dupraz
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Max Schelski
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Jisoo Kim
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany; Department of Stem Cell and Regenerative Biology, Center for Brain Science, and Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | | | - Susanne Schoch
- Institute of Neuropathology, Medical Faculty, University of Bonn, 53105 Bonn, Germany
| | - Cordelia Imig
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Frank Bradke
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany.
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Stern S, Hilton BJ, Burnside ER, Dupraz S, Handley EE, Gonyer JM, Brakebusch C, Bradke F. RhoA drives actin compaction to restrict axon regeneration and astrocyte reactivity after CNS injury. Neuron 2021; 109:3436-3455.e9. [PMID: 34508667 DOI: 10.1016/j.neuron.2021.08.014] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 07/16/2021] [Accepted: 08/11/2021] [Indexed: 12/26/2022]
Abstract
An inhibitory extracellular milieu and neuron-intrinsic processes prevent axons from regenerating in the adult central nervous system (CNS). Here we show how the two aspects are interwoven. Genetic loss-of-function experiments determine that the small GTPase RhoA relays extracellular inhibitory signals to the cytoskeleton by adapting mechanisms set in place during neuronal polarization. In response to extracellular inhibitors, neuronal RhoA restricts axon regeneration by activating myosin II to compact actin and, thereby, restrain microtubule protrusion. However, astrocytic RhoA restricts injury-induced astrogliosis through myosin II independent of microtubules by activating Yes-activated protein (YAP) signaling. Cell-type-specific deletion in spinal-cord-injured mice shows that neuronal RhoA activation prevents axon regeneration, whereas astrocytic RhoA is beneficial for regenerating axons. These data demonstrate how extracellular inhibitors regulate axon regeneration, shed light on the capacity of reactive astrocytes to be growth inhibitory after CNS injury, and reveal cell-specific RhoA targeting as a promising therapeutic avenue.
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Affiliation(s)
- Sina Stern
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Brett J Hilton
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Emily R Burnside
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Sebastian Dupraz
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Emily E Handley
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Jessica M Gonyer
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany
| | - Cord Brakebusch
- Biotech Research and Innovation Centre, Biomedical Institute, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark
| | - Frank Bradke
- Laboratory of Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg Campus 1/99, 53127 Bonn, Germany.
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Hilton BJ, Bradke F. Growing Myelin around Regenerated Axons after CNS Injury. Neuron 2021; 108:797-798. [PMID: 33301720 DOI: 10.1016/j.neuron.2020.10.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
In this issue of Neuron, Wang et al. demonstrate that both cell-intrinsic and -extrinsic factors restrict the myelination of newly regenerated axons. Pharmalogical targeting of GPR17 signaling in oligodendrocyte precursor cells (OPCs) and microglial inhibition of oligodendrocyte maturation together promote robust myelination of regenerated axons after CNS injury.
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Affiliation(s)
- Brett J Hilton
- Laboratory of Axon Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg-Campus 1, Building 99, 53127 Bonn, Germany.
| | - Frank Bradke
- Laboratory of Axon Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Venusberg-Campus 1, Building 99, 53127 Bonn, Germany.
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Dupraz S, Hilton BJ, Husch A, Santos TE, Coles CH, Stern S, Brakebusch C, Bradke F. RhoA Controls Axon Extension Independent of Specification in the Developing Brain. Curr Biol 2019; 29:3874-3886.e9. [PMID: 31679934 DOI: 10.1016/j.cub.2019.09.040] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 08/22/2019] [Accepted: 09/16/2019] [Indexed: 12/22/2022]
Abstract
The specification of an axon and its subsequent outgrowth are key steps during neuronal polarization, a prerequisite to wire the brain. The Rho-guanosine triphosphatase (GTPase) RhoA is believed to be a central player in these processes. However, its physiological role has remained undefined. Here, genetic loss- and gain-of-function experiments combined with time-lapse microscopy, cell culture, and in vivo analysis show that RhoA is not involved in axon specification but confines the initiation of neuronal polarization and axon outgrowth during development. Biochemical analysis and super-resolution microscopy together with molecular and pharmacological manipulations reveal that RhoA restrains axon growth by activating myosin-II-mediated actin arc formation in the growth cone to prevent microtubules from protruding toward the leading edge. Through this mechanism, RhoA regulates the duration of axon growth and pause phases, thus controlling the tightly timed extension of developing axons. Thereby, this work unravels physiologically relevant players coordinating actin-microtubule interactions during axon growth.
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Affiliation(s)
- Sebastian Dupraz
- Axonal Growth and Regeneration Group, German Center for Neurodegenerative Diseases (DZNE), Venusberg-Campus 1, Building 99, 53127 Bonn, Germany
| | - Brett J Hilton
- Axonal Growth and Regeneration Group, German Center for Neurodegenerative Diseases (DZNE), Venusberg-Campus 1, Building 99, 53127 Bonn, Germany
| | - Andreas Husch
- Axonal Growth and Regeneration Group, German Center for Neurodegenerative Diseases (DZNE), Venusberg-Campus 1, Building 99, 53127 Bonn, Germany
| | - Telma E Santos
- Axonal Growth and Regeneration Group, German Center for Neurodegenerative Diseases (DZNE), Venusberg-Campus 1, Building 99, 53127 Bonn, Germany
| | - Charlotte H Coles
- Axonal Growth and Regeneration Group, German Center for Neurodegenerative Diseases (DZNE), Venusberg-Campus 1, Building 99, 53127 Bonn, Germany
| | - Sina Stern
- Axonal Growth and Regeneration Group, German Center for Neurodegenerative Diseases (DZNE), Venusberg-Campus 1, Building 99, 53127 Bonn, Germany
| | - Cord Brakebusch
- Biotech Research & Innovation Centre, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark
| | - Frank Bradke
- Axonal Growth and Regeneration Group, German Center for Neurodegenerative Diseases (DZNE), Venusberg-Campus 1, Building 99, 53127 Bonn, Germany.
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Duncan GJ, Manesh SB, Hilton BJ, Assinck P, Plemel JR, Tetzlaff W. The fate and function of oligodendrocyte progenitor cells after traumatic spinal cord injury. Glia 2019; 68:227-245. [PMID: 31433109 DOI: 10.1002/glia.23706] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 07/24/2019] [Accepted: 08/01/2019] [Indexed: 12/27/2022]
Abstract
Oligodendrocyte progenitor cells (OPCs) are the most proliferative and dispersed population of progenitor cells in the adult central nervous system, which allows these cells to rapidly respond to damage. Oligodendrocytes and myelin are lost after traumatic spinal cord injury (SCI), compromising efficient conduction and, potentially, the long-term health of axons. In response, OPCs proliferate and then differentiate into new oligodendrocytes and Schwann cells to remyelinate axons. This culminates in highly efficient remyelination following experimental SCI in which nearly all intact demyelinated axons are remyelinated in rodent models. However, myelin regeneration comprises only one role of OPCs following SCI. OPCs contribute to scar formation after SCI and restrict the regeneration of injured axons. Moreover, OPCs alter their gene expression following demyelination, express cytokines and perpetuate the immune response. Here, we review the functional contribution of myelin regeneration and other recently uncovered roles of OPCs and their progeny to repair following SCI.
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Affiliation(s)
- Greg J Duncan
- Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health and Science University, Portland, Oregon
| | - Sohrab B Manesh
- Graduate Program in Neuroscience, International Collaboration on Repair Discoveries (ICORD), University of British Columbia (UBC), Vancouver, British Columbia, Canada
| | - Brett J Hilton
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Bonn, Germany
| | - Peggy Assinck
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | - Jason R Plemel
- Department of Medicine, Division of Neurology, Neuroscience and Mental Health Institute, University of Alberta, Calgary, Alberta, Canada
| | - Wolfram Tetzlaff
- Graduate Program in Neuroscience, International Collaboration on Repair Discoveries (ICORD), University of British Columbia (UBC), Vancouver, British Columbia, Canada.,Departments of Zoology and Surgery, University of British Columbia, Vancouver, British Columbia, Canada
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Tedeschi A, Dupraz S, Curcio M, Laskowski CJ, Schaffran B, Flynn KC, Santos TE, Stern S, Hilton BJ, Larson MJE, Gurniak CB, Witke W, Bradke F. ADF/Cofilin-Mediated Actin Turnover Promotes Axon Regeneration in the Adult CNS. Neuron 2019; 103:1073-1085.e6. [PMID: 31400829 DOI: 10.1016/j.neuron.2019.07.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 06/06/2019] [Accepted: 07/08/2019] [Indexed: 11/27/2022]
Abstract
Injured axons fail to regenerate in the adult CNS, which contrasts with their vigorous growth during embryonic development. We explored the potential of re-initiating axon extension after injury by reactivating the molecular mechanisms that drive morphogenetic transformation of neurons during development. Genetic loss- and gain-of-function experiments followed by time-lapse microscopy, in vivo imaging, and whole-mount analysis show that axon regeneration is fueled by elevated actin turnover. Actin depolymerizing factor (ADF)/cofilin controls actin turnover to sustain axon regeneration after spinal cord injury through its actin-severing activity. This pinpoints ADF/cofilin as a key regulator of axon growth competence, irrespective of developmental stage. These findings reveal the central role of actin dynamics regulation in this process and elucidate a core mechanism underlying axon growth after CNS trauma. Thereby, neurons maintain the capacity to stimulate developmental programs during adult life, expanding their potential for plasticity. Thus, actin turnover is a key process for future regenerative interventions.
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Affiliation(s)
- Andrea Tedeschi
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Sebastian Dupraz
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Michele Curcio
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Claudia J Laskowski
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Barbara Schaffran
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Kevin C Flynn
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Telma E Santos
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Sina Stern
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Brett J Hilton
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Molly J E Larson
- Center for Brain and Spinal Cord Repair, Department of Neuroscience, Wexner Medical Center, The Ohio State University, 460 W. 12th Ave., Columbus, OH 43210, USA
| | - Christine B Gurniak
- Institute of Genetics, University of Bonn, Karlrobert-Kreiten-Str. 13, 53115 Bonn, Germany
| | - Walter Witke
- Institute of Genetics, University of Bonn, Karlrobert-Kreiten-Str. 13, 53115 Bonn, Germany
| | - Frank Bradke
- Axonal Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany.
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Hilton BJ, Blanquie O, Tedeschi A, Bradke F. High-resolution 3D imaging and analysis of axon regeneration in unsectioned spinal cord with or without tissue clearing. Nat Protoc 2019; 14:1235-1260. [DOI: 10.1038/s41596-019-0140-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 01/17/2019] [Indexed: 12/12/2022]
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8
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Schaffran B, Hilton BJ, Bradke F. Imaging in vivo dynamics of sensory axon responses to CNS injury. Exp Neurol 2019; 317:110-118. [PMID: 30794766 DOI: 10.1016/j.expneurol.2019.02.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/13/2019] [Accepted: 02/17/2019] [Indexed: 01/25/2023]
Abstract
Axons in the adult mammalian brain and spinal cord fail to regenerate upon lesion. In vivo imaging serves as a tool to investigate the immediate response of axons to injury and how the same injured axons behave over time. Here, we describe the dynamic changes that injured sensory axons undergo and methods of imaging them in vivo. First, we explain how sensory axons in the dorsal column of the adult mouse spinal cord respond to axotomy. Then, we highlight practical considerations for implementing two-photon based in vivo imaging of these axons. Finally, we describe future directions for this technique, including the possibility of in vivo imaging of subcellular dynamics within the axon.
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Affiliation(s)
| | - Brett J Hilton
- German Center for Neurodegenerative Diseases, Bonn, Germany
| | - Frank Bradke
- German Center for Neurodegenerative Diseases, Bonn, Germany.
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Duncan GJ, Manesh SB, Hilton BJ, Assinck P, Liu J, Moulson A, Plemel JR, Tetzlaff W. Locomotor recovery following contusive spinal cord injury does not require oligodendrocyte remyelination. Nat Commun 2018; 9:3066. [PMID: 30076300 PMCID: PMC6076268 DOI: 10.1038/s41467-018-05473-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 06/28/2018] [Indexed: 12/16/2022] Open
Abstract
Remyelination occurs after spinal cord injury (SCI) but its functional relevance is unclear. We assessed the necessity of myelin regulatory factor (Myrf) in remyelination after contusive SCI by deleting the gene from platelet-derived growth factor receptor alpha positive (PDGFRα-positive) oligodendrocyte progenitor cells (OPCs) in mice prior to SCI. While OPC proliferation and density are not altered by Myrf inducible knockout after SCI, the accumulation of new oligodendrocytes is largely prevented. This greatly inhibits myelin regeneration, resulting in a 44% reduction in myelinated axons at the lesion epicenter. However, spontaneous locomotor recovery after SCI is not altered by remyelination failure. In controls with functional MYRF, locomotor recovery precedes the onset of most oligodendrocyte myelin regeneration. Collectively, these data demonstrate that MYRF expression in PDGFRα-positive cell derived oligodendrocytes is indispensable for myelin regeneration following contusive SCI but that oligodendrocyte remyelination is not required for spontaneous recovery of stepping.
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Affiliation(s)
- Greg J Duncan
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia (UBC), 818 West 10th Avenue, V5Z 1M9, Vancouver, BC, Canada
- Department of Zoology, University of British Columbia, 4200-6270 University Blvd, Vancouver, V6T 1Z4, BC, Canada
| | - Sohrab B Manesh
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia (UBC), 818 West 10th Avenue, V5Z 1M9, Vancouver, BC, Canada
- Graduate Program in Neuroscience, University of British Columbia, 3402-2215 Wesbrook Mall, Vancouver, V6T 1Z3, BC, Canada
| | - Brett J Hilton
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia (UBC), 818 West 10th Avenue, V5Z 1M9, Vancouver, BC, Canada
- Department of Zoology, University of British Columbia, 4200-6270 University Blvd, Vancouver, V6T 1Z4, BC, Canada
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Sigmund-Freud-Straße 27, 53127, Bonn, Germany
| | - Peggy Assinck
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia (UBC), 818 West 10th Avenue, V5Z 1M9, Vancouver, BC, Canada
- Graduate Program in Neuroscience, University of British Columbia, 3402-2215 Wesbrook Mall, Vancouver, V6T 1Z3, BC, Canada
| | - Jie Liu
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia (UBC), 818 West 10th Avenue, V5Z 1M9, Vancouver, BC, Canada
| | - Aaron Moulson
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia (UBC), 818 West 10th Avenue, V5Z 1M9, Vancouver, BC, Canada
- Department of Zoology, University of British Columbia, 4200-6270 University Blvd, Vancouver, V6T 1Z4, BC, Canada
| | - Jason R Plemel
- The Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Drive NW, T2N 4N1, Calgary, AB, Canada
| | - Wolfram Tetzlaff
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia (UBC), 818 West 10th Avenue, V5Z 1M9, Vancouver, BC, Canada.
- Department of Zoology, University of British Columbia, 4200-6270 University Blvd, Vancouver, V6T 1Z4, BC, Canada.
- Department of Surgery, University of British Columbia, 2775 Laurel Street, Vancouver, V5Z 1M9, BC, Canada.
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Abstract
In the adult mammalian central nervous system (CNS), neurons typically fail to regenerate their axons after injury. During development, by contrast, neurons extend axons effectively. A variety of intracellular mechanisms mediate this difference, including changes in gene expression, the ability to form a growth cone, differences in mitochondrial function/axonal transport and the efficacy of synaptic transmission. In turn, these intracellular processes are linked to extracellular differences between the developing and adult CNS. During development, the extracellular environment directs axon growth and circuit formation. In adulthood, by contrast, extracellular factors, such as myelin and the extracellular matrix, restrict axon growth. Here, we discuss whether the reactivation of developmental processes can elicit axon regeneration in the injured CNS.
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Affiliation(s)
- Brett J Hilton
- Laboratory for Axon Growth and Regeneration, German Centre for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Frank Bradke
- Laboratory for Axon Growth and Regeneration, German Centre for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
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Hilton BJ, Moulson AJ, Tetzlaff W. Neuroprotection and secondary damage following spinal cord injury: concepts and methods. Neurosci Lett 2017; 652:3-10. [DOI: 10.1016/j.neulet.2016.12.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 11/28/2016] [Accepted: 12/02/2016] [Indexed: 01/29/2023]
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McDole Somera T, Bailey B, Barott K, Grasis J, Hatay M, Hilton BJ, Hisakawa N, Nosrat B, Nulton J, Silveira CB, Sullivan C, Brainard RE, Rohwer F. Energetic differences between bacterioplankton trophic groups and coral reef resistance. Proc Biol Sci 2016; 283:20160467. [PMID: 27097927 PMCID: PMC4855391 DOI: 10.1098/rspb.2016.0467] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 03/31/2016] [Indexed: 01/03/2023] Open
Abstract
Coral reefs are among the most productive and diverse marine ecosystems on the Earth. They are also particularly sensitive to changing energetic requirements by different trophic levels. Microbialization specifically refers to the increase in the energetic metabolic demands of microbes relative to macrobes and is significantly correlated with increasing human influence on coral reefs. In this study, metabolic theory of ecology is used to quantify the relative contributions of two broad bacterioplankton groups, autotrophs and heterotrophs, to energy flux on 27 Pacific coral reef ecosystems experiencing human impact to varying degrees. The effective activation energy required for photosynthesis is lower than the average energy of activation for the biochemical reactions of the Krebs cycle, and changes in the proportional abundance of these two groups can greatly affect rates of energy and materials cycling. We show that reef-water communities with a higher proportional abundance of microbial autotrophs expend more metabolic energy per gram of microbial biomass. Increased energy and materials flux through fast energy channels (i.e. water-column associated microbial autotrophs) may dampen the detrimental effects of increased heterotrophic loads (e.g. coral disease) on coral reef systems experiencing anthropogenic disturbance.
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Affiliation(s)
- Tracey McDole Somera
- Biology Department, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
| | - Barbara Bailey
- Department of Mathematics and Statistics, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
| | - Katie Barott
- Biology Department, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
| | - Juris Grasis
- Biology Department, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
| | - Mark Hatay
- Biology Department, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
| | - Brett J Hilton
- Biology Department, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
| | - Nao Hisakawa
- Biology Department, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
| | - Bahador Nosrat
- Biology Department, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
| | - James Nulton
- Department of Mathematics and Statistics, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
| | - Cynthia B Silveira
- Biology Department, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
| | - Chris Sullivan
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gillman Drive, La Jolla, CA 92093, USA
| | - Russell E Brainard
- NOAA Fisheries, Pacific Islands Fisheries Science Center, 1125 B Ala Moana Boulevard, Honolulu, HI 96814, USA
| | - Forest Rohwer
- Biology Department, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
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Geoffroy CG, Hilton BJ, Tetzlaff W, Zheng B. Evidence for an Age-Dependent Decline in Axon Regeneration in the Adult Mammalian Central Nervous System. Cell Rep 2016; 15:238-46. [PMID: 27050519 DOI: 10.1016/j.celrep.2016.03.028] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 01/28/2016] [Accepted: 03/07/2016] [Indexed: 10/22/2022] Open
Abstract
How aging impacts axon regeneration after CNS injury is not known. We assessed the impact of age on axon regeneration induced by Pten deletion in corticospinal and rubrospinal neurons, two neuronal populations with distinct innate regenerative abilities. As in young mice, Pten deletion in older mice remains effective in preventing axotomy-induced decline in neuron-intrinsic growth state, as assessed by mTOR activity, neuronal soma size, and axonal growth proximal to a spinal cord injury. However, axonal regeneration distal to injury is greatly diminished, accompanied by increased expression of astroglial and inflammatory markers at the injury site. Thus, the mammalian CNS undergoes an age-dependent decline in axon regeneration, as revealed when neuron-intrinsic growth state is elevated. These results have important implications for developing strategies to promote axonal repair after CNS injuries or diseases, which increasingly affect middle-aged to aging populations.
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Affiliation(s)
- Cédric G Geoffroy
- Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, CA 92093-0691, USA
| | - Brett J Hilton
- International Collaboration on Repair Discoveries, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Wolfram Tetzlaff
- International Collaboration on Repair Discoveries, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Surgery, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
| | - Binhai Zheng
- Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, CA 92093-0691, USA.
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15
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Kim BJ, Hancock BM, Bermudez A, Del Cid N, Reyes E, van Sorge NM, Lauth X, Smurthwaite CA, Hilton BJ, Stotland A, Banerjee A, Buchanan J, Wolkowicz R, Traver D, Doran KS. Bacterial induction of Snail1 contributes to blood-brain barrier disruption. J Clin Invest 2015; 125:2473-83. [PMID: 25961453 DOI: 10.1172/jci74159] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 04/06/2015] [Indexed: 12/23/2022] Open
Abstract
Bacterial meningitis is a serious infection of the CNS that results when blood-borne bacteria are able to cross the blood-brain barrier (BBB). Group B Streptococcus (GBS) is the leading cause of neonatal meningitis; however, the molecular mechanisms that regulate bacterial BBB disruption and penetration are not well understood. Here, we found that infection of human brain microvascular endothelial cells (hBMECs) with GBS and other meningeal pathogens results in the induction of host transcriptional repressor Snail1, which impedes expression of tight junction genes. Moreover, GBS infection also induced Snail1 expression in murine and zebrafish models. Tight junction components ZO-1, claudin 5, and occludin were decreased at both the transcript and protein levels in hBMECs following GBS infection, and this repression was dependent on Snail1 induction. Bacteria-independent Snail1 expression was sufficient to facilitate tight junction disruption, promoting BBB permeability to allow bacterial passage. GBS induction of Snail1 expression was dependent on the ERK1/2/MAPK signaling cascade and bacterial cell wall components. Finally, overexpression of a dominant-negative Snail1 homolog in zebrafish elevated transcription of tight junction protein-encoding genes and increased zebrafish survival in response to GBS challenge. Taken together, our data support a Snail1-dependent mechanism of BBB disruption and penetration by meningeal pathogens.
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16
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Anenberg E, Arstikaitis P, Niitsu Y, Harrison TC, Boyd JD, Hilton BJ, Tetzlaff W, Murphy TH. Ministrokes in channelrhodopsin-2 transgenic mice reveal widespread deficits in motor output despite maintenance of cortical neuronal excitability. J Neurosci 2014; 34:1094-104. [PMID: 24453302 PMCID: PMC6705317 DOI: 10.1523/jneurosci.1442-13.2014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 11/28/2013] [Accepted: 12/04/2013] [Indexed: 11/21/2022] Open
Abstract
We evaluated the effects of ministrokes targeted to individual pial arterioles on motor function in Thy-1 line 18 channelrhodopsin-2 (ChR2) transgenic mice within the first hours after ischemia. Using optogenetics, we directly assessed both the excitability and motor output of cortical neurons in a manner independent of behavioral state or training. Occlusion of individual arterioles within the motor cortex led to a ministroke that was verified using laser speckle contrast imaging. Surprisingly, ministrokes targeted to a relatively small region of the forelimb motor map, with an ischemic core of 0.07 ± 0.03 mm(2), impaired motor responses evoked from points across widespread areas of motor cortex even 1.5 mm away. Contrasting averaged ChR2-evoked electroencephalographic, spinal (ChR2 evoked potential), and electromyographic responses revealed a mismatch between measures of cortical excitability and motor output within 60 min after stroke. This mismatch suggests that apparently excitable cortical neurons (even >1 mm into peri-infarct areas, away from the infarct core) were impaired in their capacity to generate spinal potentials leading to even more severe deficits in motor output at muscles. We suggest that ischemia, targeted to a subset of motor cortex, leads to relatively small reductions in excitability within motor cortex, and cumulative depression of both descending spinal circuits and motor output in response to the activation of widespread cortical territories even outside of the area directly affected by the ischemia.
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Affiliation(s)
| | | | | | | | | | - Brett J. Hilton
- Department of Zoology, and
- International Collaboration on Repair Discoveries, University of British Columbia at Vancouver, Vancouver, British Columbia V6T 1Z3, Canada
| | - Wolfram Tetzlaff
- Department of Zoology, and
- International Collaboration on Repair Discoveries, University of British Columbia at Vancouver, Vancouver, British Columbia V6T 1Z3, Canada
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17
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Streijger F, Plunet WT, Lee JHT, Liu J, Lam CK, Park S, Hilton BJ, Fransen BL, Matheson KAJ, Assinck P, Kwon BK, Tetzlaff W. Ketogenic diet improves forelimb motor function after spinal cord injury in rodents. PLoS One 2013; 8:e78765. [PMID: 24223849 PMCID: PMC3817084 DOI: 10.1371/journal.pone.0078765] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 09/16/2013] [Indexed: 11/29/2022] Open
Abstract
High fat, low carbohydrate ketogenic diets (KD) are validated non-pharmacological treatments for some forms of drug-resistant epilepsy. Ketones reduce neuronal excitation and promote neuroprotection. Here, we investigated the efficacy of KD as a treatment for acute cervical spinal cord injury (SCI) in rats. Starting 4 hours following C5 hemi-contusion injury animals were fed either a standard carbohydrate based diet or a KD formulation with lipid to carbohydrate plus protein ratio of 3:1. The forelimb functional recovery was evaluated for 14 weeks, followed by quantitative histopathology. Post-injury 3:1 KD treatment resulted in increased usage and range of motion of the affected forepaw. Furthermore, KD improved pellet retrieval with recovery of wrist and digit movements. Importantly, after returning to a standard diet after 12 weeks of KD treatment, the improved forelimb function remained stable. Histologically, the spinal cords of KD treated animals displayed smaller lesion areas and more grey matter sparing. In addition, KD treatment increased the number of glucose transporter-1 positive blood vessels in the lesion penumbra and monocarboxylate transporter-1 (MCT1) expression. Pharmacological inhibition of MCTs with 4-CIN (α-cyano-4-hydroxycinnamate) prevented the KD-induced neuroprotection after SCI, In conclusion, post-injury KD effectively promotes functional recovery and is neuroprotective after cervical SCI. These beneficial effects require the function of monocarboxylate transporters responsible for ketone uptake and link the observed neuroprotection directly to the function of ketones, which are known to exert neuroprotection by multiple mechanisms. Our data suggest that current clinical nutritional guidelines, which include relatively high carbohydrate contents, should be revisited.
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Affiliation(s)
- Femke Streijger
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Center, Vancouver, British Columbia, Canada
| | - Ward T. Plunet
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Center, Vancouver, British Columbia, Canada
| | - Jae H. T. Lee
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Center, Vancouver, British Columbia, Canada
| | - Jie Liu
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Center, Vancouver, British Columbia, Canada
| | - Clarrie K. Lam
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Center, Vancouver, British Columbia, Canada
| | - Soeyun Park
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Center, Vancouver, British Columbia, Canada
| | - Brett J. Hilton
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Center, Vancouver, British Columbia, Canada
| | - Bas L. Fransen
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Center, Vancouver, British Columbia, Canada
| | - Keely A. J. Matheson
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Center, Vancouver, British Columbia, Canada
| | - Peggy Assinck
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Center, Vancouver, British Columbia, Canada
| | - Brian K. Kwon
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Center, Vancouver, British Columbia, Canada
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- Combined Neurosurgical and Orthopaedic Spine Program, Department of Orthopaedics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Wolfram Tetzlaff
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Center, Vancouver, British Columbia, Canada
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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Smurthwaite CA, Hilton BJ, O'Hanlon R, Stolp ZD, Hancock BM, Abbadessa D, Stotland A, Sklar LA, Wolkowicz R. Fluorescent genetic barcoding in mammalian cells for enhanced multiplexing capabilities in flow cytometry. Cytometry A 2013; 85:105-13. [DOI: 10.1002/cyto.a.22406] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 10/01/2013] [Accepted: 10/04/2013] [Indexed: 01/19/2023]
Affiliation(s)
| | - Brett J. Hilton
- Department of Biology; San Diego State University; San Diego California 92182
| | - Ryan O'Hanlon
- Department of Biology; San Diego State University; San Diego California 92182
| | - Zachary D. Stolp
- Department of Biology; San Diego State University; San Diego California 92182
| | - Bryan M. Hancock
- Department of Biology; San Diego State University; San Diego California 92182
| | - Darin Abbadessa
- Department of Biology; San Diego State University; San Diego California 92182
| | - Aleksandr Stotland
- Department of Biology; San Diego State University; San Diego California 92182
| | - Larry A. Sklar
- UNM Center for Molecular Discovery; University of New Mexico School of Medicine; Albuquerque New Mexico 87131
- Department of Pathology; University of New Mexico School of Medicine; Albuquerque New Mexico 87131
| | - Roland Wolkowicz
- Department of Biology; San Diego State University; San Diego California 92182
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19
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Stolp ZD, Stotland A, Diaz S, Hilton BJ, Burford W, Wolkowicz R. A Novel Two-Tag System for Monitoring Transport and Cleavage through the Classical Secretory Pathway - Adaptation to HIV Envelope Processing. PLoS One 2013; 8:e68835. [PMID: 23840860 PMCID: PMC3686725 DOI: 10.1371/journal.pone.0068835] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 06/03/2013] [Indexed: 11/19/2022] Open
Abstract
The classical secretory pathway is essential for the transport of a host of proteins to the cell surface and/or extracellular matrix. While the pathway is well-established, many factors still remain to be elucidated. One of the most relevant biological processes that occur during transport involves the cleavage of pro-proteins by enzymes residing in the endoplasmic reticulum/Golgi/TransGolgi Network compartment. Teasing out the requirements involved in the classical secretory pathway and cleavage during transport would shed new light into mis-regulation leading to disease. Current methodologies fail to link transport and cleavage at the single cell level. Here, we describe a cell-based assay that relies on an engineered protein scaffold that can discriminate between transport to the cell surface, in the absence or presence of cleavage. Our novel two-tag system works in a robust and quantitative manner and distinguishes between cleaved and non-cleaved events based on cell surface expression of one or two epitope tags, respectively. Here, we have used the HIV-1 envelope as a substrate, which is cleaved during transport, as proof of principle. Importantly, this assay can be easily coupled to existing siRNA-based screens to identify novel regulators and effectors involved in transport and/or cleavage of cell surface proteins. In addition, unlike other in vivo based assays, the assay described here can also be easily adapted to drug discovery purposes.
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Affiliation(s)
- Zachary D. Stolp
- Department of Biology, San Diego State University, San Diego, California, United States of America
| | - Aleksandr Stotland
- Department of Biology, San Diego State University, San Diego, California, United States of America
| | - Samantha Diaz
- Department of Biology, San Diego State University, San Diego, California, United States of America
| | - Brett J. Hilton
- Department of Biology, San Diego State University, San Diego, California, United States of America
| | - Wesley Burford
- Department of Biology, San Diego State University, San Diego, California, United States of America
| | - Roland Wolkowicz
- Department of Biology, San Diego State University, San Diego, California, United States of America
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Hilton BJ, Assinck P, Duncan GJ, Lu D, Lo S, Tetzlaff W. Dorsolateral Funiculus Lesioning of the Mouse Cervical Spinal Cord at C4 but Not at C6 Results in Sustained Forelimb Motor Deficits. J Neurotrauma 2013; 30:1070-83. [DOI: 10.1089/neu.2012.2734] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Brett J. Hilton
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Centre, Vancouver, British Columbia, Canada
| | - Peggy Assinck
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Centre, Vancouver, British Columbia, Canada
- Graduate Program in Neuroscience, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Greg J. Duncan
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Centre, Vancouver, British Columbia, Canada
| | - Daniel Lu
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Centre, Vancouver, British Columbia, Canada
| | - Stephanie Lo
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Centre, Vancouver, British Columbia, Canada
| | - Wolfram Tetzlaff
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Centre, Vancouver, British Columbia, Canada
- Graduate Program in Neuroscience, The University of British Columbia, Vancouver, British Columbia, Canada
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Abstract
Proteases are essential at different stages of the viral life cycle and for the establishment of a successful infection. Monitoring the catalytic activity of proteases in an easy and straightforward manner can thus drastically facilitate the discovery of novel antivirals, as well as help elucidate the activity and mechanism of action of the viral protease under study. In our laboratory, we have developed an assay in T-cells with a robust read-out to monitor the proteolytic activity of HIV-1 Protease (PR). The assay utilizes the prototypic transcription factor Gal4, which consists of the N-terminal DNA-binding domain and the C-terminal trans-activation domain. The assay is based upon (1) introduction of PR in between the two Gal4 domains to obtain a PR/Gal4 fusion protein and (2) utilization of the enhanced Green Fluorescent Protein as reporter of PR activity.In order to overcome the possible cellular cytotoxicity of PR, the fusion protein in our assay is under the control of a tetracycline-inducible promoter. This ensures that it will be expressed only when needed, upon the addition of tetracycline or doxycycline. When active, PR has autocatalytic activity and cleaves itself from the Gal4 domains, resulting in the inability to induce eGFP expression. However, if PR activity is blocked or it is inactive, the two domains remain intact, resulting in eGFP expression. The assay can therefore be utilized to analyze the inhibitory effects of factors, peptides or compounds, designed on a rational- or nonrational-based approach, in the natural milieu of infection, where eGFP serves as a biosensor for PR activity.
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Hilton BJ, Wolkowicz R. An assay to monitor HIV-1 protease activity for the identification of novel inhibitors in T-cells. PLoS One 2010; 5:e10940. [PMID: 20532177 PMCID: PMC2880603 DOI: 10.1371/journal.pone.0010940] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 05/11/2010] [Indexed: 11/26/2022] Open
Abstract
The emergence of resistant HIV strains, together with the severe side-effects of existing drugs and lack of development of effective anti-HIV vaccines highlight the need for novel antivirals, as well as innovative methods to facilitate their discovery. Here, we have developed an assay in T-cells to monitor the proteolytic activity of the HIV-1 protease (PR). The assay is based on the inducible expression of HIV-1 PR fused within the Gal4 DNA-binding and transactivation domains. The fusion protein binds to the Gal4 responsive element and activates the downstream reporter, enhanced green fluorescent protein (eGFP) gene only in the presence of an effective PR Inhibitor (PI). Thus, in this assay, eGFP acts as a biosensor of PR activity, making it ideal for flow cytometry based screening. Furthermore, the assay was developed using retroviral technology in T-cells, thus providing an ideal environment for the screening of potential novel PIs in a cell-type that represents the natural milieu of HIV infection. Clones with the highest sensitivity, and robust, reliable and reproducible reporter activity, were selected. The assay is easily adaptable to other PR variants, a multiplex platform, as well as to high-throughput plate reader based assays and will greatly facilitate the search for novel peptide and chemical compound based PIs in T-cells.
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Affiliation(s)
- Brett J. Hilton
- Department of Biology, San Diego State University, San Diego, California, United States of America
| | - Roland Wolkowicz
- Department of Biology, San Diego State University, San Diego, California, United States of America
- * E-mail:
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23
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Bates AE, Hilton BJ, Harley CDG. Effects of temperature, season and locality on wasting disease in the keystone predatory sea star Pisaster ochraceus. Dis Aquat Organ 2009; 86:245-251. [PMID: 20066959 DOI: 10.3354/dao02125] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This study investigates wasting disease in the northeast Pacific keystone predatory sea star Pisaster ochraceus on the outer west coast of Vancouver Island (British Columbia, Canada). To quantify the effects of temperature, season and locality on the vulnerability of P. ochraceus to wasting disease, we conducted surveys and experiments in early and late summer. To test the prediction that a small increase in temperature would result in heightened infection intensities, we housed sea stars at different temperatures in the laboratory and caged sea stars subtidally at 2 depths. Prevalence and infection intensity were always higher in warm temperature treatments and did not differ between the sexes or with increasing size. Disease effects also varied with season and locality. Specimens held in aquaria displayed significantly higher disease prevalence and infection intensity in June versus August. Furthermore, sea stars from a sheltered inlet showed markedly higher prevalence of the disease in late summer, while wave-exposed sites had consistently low disease prevalence. Seasonal changes in reproductive potential, host condition and/or physiological acclimation, as well as differences in environmental regime among localities, may impact the dynamics of wasting disease. These results demonstrate that small increases in temperature could drive mass mortalities of Pisaster due to wasting disease, with vulnerability possibly reaching a peak in spring and in populations from sheltered localities. This is the most northern report of wasting disease in the class Asteroidea on the west coast of North America.
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Affiliation(s)
- Amanda E Bates
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada.
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