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Jeong Y, Lee SY, Choi M, Eun S. Histochemical Identification of Motor Fascicles Using Cholinesterase Staining in Rats Using a Mixed Nerve Model. Transplant Proc 2024; 56:712-714. [PMID: 38355371 DOI: 10.1016/j.transproceed.2024.01.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 01/16/2024] [Indexed: 02/16/2024]
Abstract
BACKGROUND Inappropriate matching of motor and sensory fibers after nerve repair or grafting can lead to nerve recovery failure. Identifying the motor and sensory fascicles enables surgeons to match them accurately and correctly align nerve stumps, which is crucial for neural regeneration. Very few methods have been reported to differentiate between the sensory and motor nerve fascicles, and the replicability of these techniques remains unestablished. In this study, we aimed to assess the accuracy of axonal cholinesterase (CE) histochemical staining in distinguishing motor and sensory nerve fibers. METHODS The femoral and sciatic nerves were harvested from rats. The specimens were immediately cut, frozen in isopentane, and cooled with liquid nitrogen. Nerve serial cross-sections were processed for hematoxylin and eosin staining, followed by CE histochemistry. The staining protocol solutions included acetylthiocholine iodide, phosphate buffer, cobalt sulfate hydrate, potassium phosphate monobasic, sulfuric acid, sodium bicarbonate, glutaraldehyde, and ammonium sulfide. RESULTS Cross-sections of nerves containing efferent and afferent nerve fibers in segregated fascicles showed that CE activity was confined to motor neurons. A histochemical study revealed that motor fibers with high cholinesterase activity can be differentiated from sensory fibers. The motor branches of the femoral and sciatic nerves showed specific axonal staining, whereas the sensory branch did not show any specific staining. CONCLUSION CE histochemical staining is a useful technique for distinguishing between motor and sensory nerve fibers. It can be potentially useful in improving the outcomes of nerve grafts or extremity allotransplantation surgery.
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Affiliation(s)
- Yeonjin Jeong
- Department of Plastic and Reconstructive Surgery, National Medical Center, Seoul, Korea
| | - Se Yeon Lee
- Department of Plastic and Reconstructive Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Korea
| | - Miso Choi
- Department of Plastic and Reconstructive Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Korea
| | - Seokchan Eun
- Department of Plastic and Reconstructive Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Korea.
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2
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Wu T, Zhu J, Strickland A, Ko KW, Sasaki Y, Dingwall CB, Yamada Y, Figley MD, Mao X, Neiner A, Bloom AJ, DiAntonio A, Milbrandt J. Neurotoxins subvert the allosteric activation mechanism of SARM1 to induce neuronal loss. Cell Rep 2021; 37:109872. [PMID: 34686345 PMCID: PMC8638332 DOI: 10.1016/j.celrep.2021.109872] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 07/01/2021] [Revised: 08/06/2021] [Accepted: 09/29/2021] [Indexed: 10/20/2022] Open
Abstract
SARM1 is an inducible TIR-domain NAD+ hydrolase that mediates pathological axon degeneration. SARM1 is activated by an increased ratio of NMN to NAD+, which competes for binding to an allosteric activating site. When NMN binds, the TIR domain is released from autoinhibition, activating its NAD+ hydrolase activity. The discovery of this allosteric activating site led us to hypothesize that other NAD+-related metabolites might activate SARM1. Here, we show the nicotinamide analog 3-acetylpyridine (3-AP), first identified as a neurotoxin in the 1940s, is converted to 3-APMN, which activates SARM1 and induces SARM1-dependent NAD+ depletion, axon degeneration, and neuronal death. In mice, systemic treatment with 3-AP causes rapid SARM1-dependent death, while local application to the peripheral nerve induces SARM1-dependent axon degeneration. We identify 2-aminopyridine as another SARM1-dependent neurotoxin. These findings identify SARM1 as a candidate mediator of environmental neurotoxicity and suggest that SARM1 agonists could be developed into selective agents for neurolytic therapy.
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Affiliation(s)
- Tong Wu
- Department of Genetics, Washington University Medical School, St. Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Jian Zhu
- Department of Genetics, Washington University Medical School, St. Louis, MO 63110, USA; Needleman Center for Neurometabolism and Axonal Therapeutics, Washington University School of Medicine in Saint Louis, St. Louis, MO 63114, USA
| | - Amy Strickland
- Department of Genetics, Washington University Medical School, St. Louis, MO 63110, USA
| | - Kwang Woo Ko
- Department of Developmental Biology, Washington University Medical School, St. Louis, MO 63110, USA
| | - Yo Sasaki
- Department of Genetics, Washington University Medical School, St. Louis, MO 63110, USA
| | - Caitlin B Dingwall
- Department of Genetics, Washington University Medical School, St. Louis, MO 63110, USA
| | - Yurie Yamada
- Department of Genetics, Washington University Medical School, St. Louis, MO 63110, USA
| | - Matthew D Figley
- Department of Developmental Biology, Washington University Medical School, St. Louis, MO 63110, USA
| | - Xianrong Mao
- Department of Genetics, Washington University Medical School, St. Louis, MO 63110, USA
| | - Alicia Neiner
- Department of Genetics, Washington University Medical School, St. Louis, MO 63110, USA
| | - A Joseph Bloom
- Department of Genetics, Washington University Medical School, St. Louis, MO 63110, USA; Needleman Center for Neurometabolism and Axonal Therapeutics, Washington University School of Medicine in Saint Louis, St. Louis, MO 63114, USA
| | - Aaron DiAntonio
- Department of Developmental Biology, Washington University Medical School, St. Louis, MO 63110, USA; Needleman Center for Neurometabolism and Axonal Therapeutics, Washington University School of Medicine in Saint Louis, St. Louis, MO 63114, USA.
| | - Jeffrey Milbrandt
- Department of Genetics, Washington University Medical School, St. Louis, MO 63110, USA; Needleman Center for Neurometabolism and Axonal Therapeutics, Washington University School of Medicine in Saint Louis, St. Louis, MO 63114, USA.
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3
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Vevea JD, Kusick GF, Courtney KC, Chen E, Watanabe S, Chapman ER. Synaptotagmin 7 is targeted to the axonal plasma membrane through γ-secretase processing to promote synaptic vesicle docking in mouse hippocampal neurons. eLife 2021; 10:e67261. [PMID: 34543184 PMCID: PMC8452306 DOI: 10.7554/elife.67261] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 08/27/2021] [Indexed: 12/28/2022] Open
Abstract
Synaptotagmin 7 (SYT7) has emerged as a key regulator of presynaptic function, but its localization and precise role in the synaptic vesicle cycle remain the subject of debate. Here, we used iGluSnFR to optically interrogate glutamate release, at the single-bouton level, in SYT7KO-dissociated mouse hippocampal neurons. We analyzed asynchronous release, paired-pulse facilitation, and synaptic vesicle replenishment and found that SYT7 contributes to each of these processes to different degrees. 'Zap-and-freeze' electron microscopy revealed that a loss of SYT7 diminishes docking of synaptic vesicles after a stimulus and inhibits the recovery of depleted synaptic vesicles after a stimulus train. SYT7 supports these functions from the axonal plasma membrane, where its localization and stability require both γ-secretase-mediated cleavage and palmitoylation. In summary, SYT7 is a peripheral membrane protein that controls multiple modes of synaptic vesicle (SV) exocytosis and plasticity, in part, through enhancing activity-dependent docking of SVs.
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Affiliation(s)
- Jason D Vevea
- Department of Neuroscience, University of Wisconsin-MadisonMadisonUnited States
- Howard Hughes Medical InstituteMadisonUnited States
| | - Grant F Kusick
- Department of Cell Biology, Johns Hopkins University, School of MedicineBaltimoreUnited States
- Biochemistry, Cellular and Molecular Biology Graduate Program, Johns Hopkins University, School of MedicineBaltimoreUnited States
| | - Kevin C Courtney
- Department of Neuroscience, University of Wisconsin-MadisonMadisonUnited States
- Howard Hughes Medical InstituteMadisonUnited States
| | - Erin Chen
- Department of Cell Biology, Johns Hopkins University, School of MedicineBaltimoreUnited States
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University, School of MedicineBaltimoreUnited States
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of MedicineBaltimoreUnited States
| | - Edwin R Chapman
- Department of Neuroscience, University of Wisconsin-MadisonMadisonUnited States
- Howard Hughes Medical InstituteMadisonUnited States
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Andreassi C, Luisier R, Crerar H, Darsinou M, Blokzijl-Franke S, Lenn T, Luscombe NM, Cuda G, Gaspari M, Saiardi A, Riccio A. Cytoplasmic cleavage of IMPA1 3' UTR is necessary for maintaining axon integrity. Cell Rep 2021; 34:108778. [PMID: 33626357 PMCID: PMC7918530 DOI: 10.1016/j.celrep.2021.108778] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 12/22/2020] [Accepted: 01/29/2021] [Indexed: 12/31/2022] Open
Abstract
The 3' untranslated regions (3' UTRs) of messenger RNAs (mRNAs) are non-coding sequences involved in many aspects of mRNA metabolism, including intracellular localization and translation. Incorrect processing and delivery of mRNA cause severe developmental defects and have been implicated in many neurological disorders. Here, we use deep sequencing to show that in sympathetic neuron axons, the 3' UTRs of many transcripts undergo cleavage, generating isoforms that express the coding sequence with a short 3' UTR and stable 3' UTR-derived fragments of unknown function. Cleavage of the long 3' UTR of Inositol Monophosphatase 1 (IMPA1) mediated by a protein complex containing the endonuclease argonaute 2 (Ago2) generates a translatable isoform that is necessary for maintaining the integrity of sympathetic neuron axons. Thus, our study provides a mechanism of mRNA metabolism that simultaneously regulates local protein synthesis and generates an additional class of 3' UTR-derived RNAs.
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Affiliation(s)
- Catia Andreassi
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
| | | | - Hamish Crerar
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
| | - Marousa Darsinou
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
| | - Sasja Blokzijl-Franke
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
| | - Tchern Lenn
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
| | - Nicholas M Luscombe
- Francis Crick Institute, London NW1 1AT, UK; UCL Genetics Institute, University College London, London WC1E 6BT, UK
| | - Giovanni Cuda
- Research Centre for Advanced Biochemistry and Molecular Biology, Department of Experimental and Clinical Medicine, Magna Graecia University of Catanzaro, Catanzaro 88100, Italy
| | - Marco Gaspari
- Research Centre for Advanced Biochemistry and Molecular Biology, Department of Experimental and Clinical Medicine, Magna Graecia University of Catanzaro, Catanzaro 88100, Italy
| | - Adolfo Saiardi
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
| | - Antonella Riccio
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK.
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5
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Chandrasekhar A, Komirishetty P, Areti A, Krishnan A, Zochodne DW. Dual Specificity Phosphatases Support Axon Plasticity and Viability. Mol Neurobiol 2021; 58:391-407. [PMID: 32959171 DOI: 10.1007/s12035-020-02119-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 05/03/2020] [Accepted: 09/05/2020] [Indexed: 02/07/2023]
Abstract
In peripheral neuropathies, axonal degeneration (AxD) impairs the prognosis for recovery. Here, we describe a role for dual specificity phosphatases (DUSPs; MAP kinase phosphatases, MKPs), in supporting autonomous axon plasticity and viability. Both DUSPs 1 and 4 were identified within intact or axotomized sensory neurons. Knockdown of DUSP 1 or 4 independently or combined impaired neurite outgrowth in adult dissociated sensory neurons. Furthermore, adult sensory neurons with DUSP knockdown were rendered sensitive to axonopathy in vitro following exposure to low, subtoxic TrpV1 (transient receptor potential cation channel subfamily V member 1) activation by capsaicin, an intervention normally supportive of growth. This was not prevented by concurrent DLK (dual leucine zipper kinase) knockdown. Ex vivo neurofilament dissolution was heightened by DUSP inhibition within explanted nerves. In vivo DUSP knockdown or inhibition was associated with more rapid loss of motor axon excitability. The addition of SARM1 (sterile alpha and TIR motif containing 1) siRNA abrogated DUSP1 and 4 mediated loss of excitability. DUSP knockdown accelerated neurofilament breakdown and there was earlier morphological evidence of myelinated axon degeneration distal to axotomy. Taken together, the findings identify a key role for DUSPs in supporting axon plasticity and survival.
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Affiliation(s)
- Ambika Chandrasekhar
- Neuroscience and Mental Health Institute and Division of Neurology, Department of Medicine, University of Alberta, 7-132A Clinical Sciences Building, 11350-83 Ave, Edmonton, AB, T6G 2G3, Canada
| | - Prashanth Komirishetty
- Neuroscience and Mental Health Institute and Division of Neurology, Department of Medicine, University of Alberta, 7-132A Clinical Sciences Building, 11350-83 Ave, Edmonton, AB, T6G 2G3, Canada
| | - Aparna Areti
- Neuroscience and Mental Health Institute and Division of Neurology, Department of Medicine, University of Alberta, 7-132A Clinical Sciences Building, 11350-83 Ave, Edmonton, AB, T6G 2G3, Canada
| | - Anand Krishnan
- Neuroscience and Mental Health Institute and Division of Neurology, Department of Medicine, University of Alberta, 7-132A Clinical Sciences Building, 11350-83 Ave, Edmonton, AB, T6G 2G3, Canada
- Department of Anatomy, Physiology, and Pharmacology, University of Saskatchewan, Saskatoon, Canada
| | - Douglas W Zochodne
- Neuroscience and Mental Health Institute and Division of Neurology, Department of Medicine, University of Alberta, 7-132A Clinical Sciences Building, 11350-83 Ave, Edmonton, AB, T6G 2G3, Canada.
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6
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Adnan G, Rubikaite A, Khan M, Reber M, Suetterlin P, Hindges R, Drescher U. The GTPase Arl8B Plays a Principle Role in the Positioning of Interstitial Axon Branches by Spatially Controlling Autophagosome and Lysosome Location. J Neurosci 2020; 40:8103-8118. [PMID: 32917789 PMCID: PMC7574663 DOI: 10.1523/jneurosci.1759-19.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [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: 07/23/2019] [Revised: 07/13/2020] [Accepted: 07/20/2020] [Indexed: 12/12/2022] Open
Abstract
Interstitial axon branching is an essential step during the establishment of neuronal connectivity. However, the exact mechanisms on how the number and position of branches are determined are still not fully understood. Here, we investigated the role of Arl8B, an adaptor molecule between lysosomes and kinesins. In chick retinal ganglion cells (RGCs), downregulation of Arl8B reduces axon branch density and shifts their location more proximally, while Arl8B overexpression leads to increased density and more distal positions of branches. These alterations correlate with changes in the location and density of lysosomes and autophagosomes along the axon shaft. Diminishing autophagy directly by knock-down of atg7, a key autophagy gene, reduces branch density, while induction of autophagy by rapamycin increases axon branching, indicating that autophagy plays a prominent role in axon branch formation. In vivo, local inactivation of autophagy in the retina using a mouse conditional knock-out approach disturbs retino-collicular map formation which is dependent on the formation of interstitial axon branches. These data suggest that Arl8B plays a principal role in the positioning of axon branches by spatially controlling autophagy, thus directly controlling formation of neural connectivity in the brain.SIGNIFICANCE STATEMENT The formation of interstitial axonal branches plays a prominent role in numerous places of the developing brain during neural circuit establishment. We show here that the GTPase Arl8B controls density and location of interstitial axon branches, and at the same time controls also density and location of the autophagy machinery. Upregulation or downregulation of autophagy in vitro promotes or inhibits axon branching. Local disruption of autophagy in vivo disturbs retino-collicular mapping. Our data suggest that Arl8B controls axon branching by controlling locally autophagy. This work is one of the first reports showing a role of autophagy during early neural circuit development and suggests that autophagy in general plays a much more prominent role during brain development than previously anticipated.
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Affiliation(s)
- Gee Adnan
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
| | - Aine Rubikaite
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
| | - Moqadisa Khan
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
| | - Michael Reber
- Krembil Research Institute, Toronto, Ontario M5T 0S8, Canada
| | - Philip Suetterlin
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
- Craniofacial Development and Stem Cell Biology, King's College London, Guy's Hospital, London SE1 9RT, United Kingdom
| | - Robert Hindges
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, United Kingdom
| | - Uwe Drescher
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, United Kingdom
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7
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Yi SA, Nam KH, Yun J, Gim D, Joe D, Kim YH, Kim HJ, Han JW, Lee J. Infection of Brain Organoids and 2D Cortical Neurons with SARS-CoV-2 Pseudovirus. Viruses 2020; 12:E1004. [PMID: 32911874 PMCID: PMC7551632 DOI: 10.3390/v12091004] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 09/02/2020] [Accepted: 09/07/2020] [Indexed: 12/31/2022] Open
Abstract
Since the global outbreak of SARS-CoV-2 (COVID-19), infections of diverse human organs along with multiple symptoms continue to be reported. However, the susceptibility of the brain to SARS-CoV-2, and the mechanisms underlying neurological infection are still elusive. Here, we utilized human embryonic stem cell-derived brain organoids and monolayer cortical neurons to investigate infection of brain with pseudotyped SARS-CoV-2 viral particles. Spike-containing SARS-CoV-2 pseudovirus infected neural layers within brain organoids. The expression of ACE2, a host cell receptor for SARS-CoV-2, was sustained during the development of brain organoids, especially in the somas of mature neurons, while remaining rare in neural stem cells. However, pseudotyped SARS-CoV-2 was observed in the axon of neurons, which lack ACE2. Neural infectivity of SARS-CoV-2 pseudovirus did not increase in proportion to viral load, but only 10% of neurons were infected. Our findings demonstrate that brain organoids provide a useful model for investigating SARS-CoV-2 entry into the human brain and elucidating the susceptibility of the brain to SARS-CoV-2.
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Affiliation(s)
- Sang Ah Yi
- Epigenome Dynamics Control Research Center, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea; (K.H.N.); (J.Y.); (D.G.); (D.J.); (J.-W.H.)
| | - Ki Hong Nam
- Epigenome Dynamics Control Research Center, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea; (K.H.N.); (J.Y.); (D.G.); (D.J.); (J.-W.H.)
| | - Jihye Yun
- Epigenome Dynamics Control Research Center, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea; (K.H.N.); (J.Y.); (D.G.); (D.J.); (J.-W.H.)
| | - Dongmin Gim
- Epigenome Dynamics Control Research Center, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea; (K.H.N.); (J.Y.); (D.G.); (D.J.); (J.-W.H.)
| | - Daeho Joe
- Epigenome Dynamics Control Research Center, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea; (K.H.N.); (J.Y.); (D.G.); (D.J.); (J.-W.H.)
| | - Yong Ho Kim
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Korea;
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon 16419, Korea
- Department of Nano Engineering, Sungkyunkwan University, Suwon 16419, Korea
- Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University, Suwon 16419, Korea
- Imnewrun Biosciences Inc., Suwon 16419, Korea;
| | - Han-Joo Kim
- Imnewrun Biosciences Inc., Suwon 16419, Korea;
| | - Jeung-Whan Han
- Epigenome Dynamics Control Research Center, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea; (K.H.N.); (J.Y.); (D.G.); (D.J.); (J.-W.H.)
| | - Jaecheol Lee
- Epigenome Dynamics Control Research Center, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea; (K.H.N.); (J.Y.); (D.G.); (D.J.); (J.-W.H.)
- Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University, Suwon 16419, Korea
- Imnewrun Biosciences Inc., Suwon 16419, Korea;
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8
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Chung HL, Wangler MF, Marcogliese PC, Jo J, Ravenscroft TA, Zuo Z, Duraine L, Sadeghzadeh S, Li-Kroeger D, Schmidt RE, Pestronk A, Rosenfeld JA, Burrage L, Herndon MJ, Chen S, Shillington A, Vawter-Lee M, Hopkin R, Rodriguez-Smith J, Henrickson M, Lee B, Moser AB, Jones RO, Watkins P, Yoo T, Mar S, Choi M, Bucelli RC, Yamamoto S, Lee HK, Prada CE, Chae JH, Vogel TP, Bellen HJ. Loss- or Gain-of-Function Mutations in ACOX1 Cause Axonal Loss via Different Mechanisms. Neuron 2020; 106:589-606.e6. [PMID: 32169171 PMCID: PMC7289150 DOI: 10.1016/j.neuron.2020.02.021] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [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: 08/13/2019] [Revised: 01/03/2020] [Accepted: 02/13/2020] [Indexed: 12/01/2022]
Abstract
ACOX1 (acyl-CoA oxidase 1) encodes the first and rate-limiting enzyme of the very-long-chain fatty acid (VLCFA) β-oxidation pathway in peroxisomes and leads to H2O2 production. Unexpectedly, Drosophila (d) ACOX1 is mostly expressed and required in glia, and loss of ACOX1 leads to developmental delay, pupal death, reduced lifespan, impaired synaptic transmission, and glial and axonal loss. Patients who carry a previously unidentified, de novo, dominant variant in ACOX1 (p.N237S) also exhibit glial loss. However, this mutation causes increased levels of ACOX1 protein and function resulting in elevated levels of reactive oxygen species in glia in flies and murine Schwann cells. ACOX1 (p.N237S) patients exhibit a severe loss of Schwann cells and neurons. However, treatment of flies and primary Schwann cells with an antioxidant suppressed the p.N237S-induced neurodegeneration. In summary, both loss and gain of ACOX1 lead to glial and neuronal loss, but different mechanisms are at play and require different treatments.
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Affiliation(s)
- Hyung-Lok Chung
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael F Wangler
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Paul C Marcogliese
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Juyeon Jo
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Department of Pediatrics, Section of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Thomas A Ravenscroft
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Zhongyuan Zuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Lita Duraine
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Sina Sadeghzadeh
- Department of Psychology, Harvard University, Cambridge, MA 02138, USA
| | - David Li-Kroeger
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Robert E Schmidt
- Department of Pathology and Immunology, Division of Neuropathology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Alan Pestronk
- Department of Pathology and Immunology, Division of Neuropathology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lindsay Burrage
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mitchell J Herndon
- Department of Pathology and Immunology, Division of Neuropathology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Shan Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Amelle Shillington
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Marissa Vawter-Lee
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA; Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Robert Hopkin
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Jackeline Rodriguez-Smith
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA; Division of Rheumatology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Michael Henrickson
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA; Division of Rheumatology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ann B Moser
- Division of Neurogenetics, Kennedy Krieger Institute, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Richard O Jones
- Division of Neurogenetics, Kennedy Krieger Institute, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Paul Watkins
- Division of Neurogenetics, Kennedy Krieger Institute, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Taekyeong Yoo
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Soe Mar
- Department of Neurology, St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Murim Choi
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Pediatrics, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Robert C Bucelli
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hyun Kyoung Lee
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Pediatrics, Section of Neurology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Carlos E Prada
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Jong-Hee Chae
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Tiphanie P Vogel
- Department of Pediatrics, Section of Rheumatology, Baylor College of Medicine, Center for Human Immunobiology, Texas Children's Hospital, Houston, TX 77030, USA
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA.
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9
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Mohamedi Y, Fontanil T, Cobo T, Cal S, Obaya AJ. New Insights into ADAMTS Metalloproteases in the Central Nervous System. Biomolecules 2020; 10:biom10030403. [PMID: 32150898 PMCID: PMC7175268 DOI: 10.3390/biom10030403] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 02/24/2020] [Accepted: 03/02/2020] [Indexed: 12/13/2022] Open
Abstract
Components of the extracellular matrix (ECM) are key players in regulating cellular functions throughout the whole organism. In fact, ECM components not only participate in tissue organization but also contribute to processes such as cellular maintenance, proliferation, and migration, as well as to support for various signaling pathways. In the central nervous system (CNS), proteoglycans of the lectican family, such as versican, aggrecan, brevican, and neurocan, are important constituents of the ECM. In recent years, members of this family have been found to be involved in the maintenance of CNS homeostasis and to participate directly in processes such as the organization of perineural nets, the regulation of brain plasticity, CNS development, brain injury repair, axonal guidance, and even the altering of synaptic responses. ADAMTSs are a family of “A disintegrin and metalloproteinase with thrombospondin motifs” proteins that have been found to be involved in a multitude of processes through the degradation of lecticans and other proteoglycans. Recently, alterations in ADAMTS expression and activity have been found to be involved in neuronal disorders such as stroke, neurodegeneration, schizophrenia, and even Alzheimer’s disease, which in turn may suggest their potential use as therapeutic targets. Herein, we summarize the different roles of ADAMTSs in regulating CNS events through interactions and the degradation of ECM components (more specifically, the lectican family of proteoglycans).
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Affiliation(s)
- Yamina Mohamedi
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain; (Y.M.); (T.F.); (S.C.)
- Departamento de Biología Funcional, Área de Fisiología, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain
- Instituto Universitario de Oncología, IUOPA, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain
| | - Tania Fontanil
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain; (Y.M.); (T.F.); (S.C.)
- Departamento de Biología Funcional, Área de Fisiología, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain
- Instituto Universitario de Oncología, IUOPA, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain
- Departamento de Investigación, Instituto Ordóñez, 33012 Oviedo, Asturias, Spain
| | - Teresa Cobo
- Departamento de Cirugía y Especialidades Médico-Quirúrgicas, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain;
- Instituto Asturiano de Odontología, 33006 Oviedo, Asturias, Spain
| | - Santiago Cal
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain; (Y.M.); (T.F.); (S.C.)
- Instituto Universitario de Oncología, IUOPA, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain
| | - Alvaro J. Obaya
- Departamento de Biología Funcional, Área de Fisiología, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain
- Instituto Universitario de Oncología, IUOPA, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain
- Correspondence:
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10
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zur Nedden S, Eith R, Schwarzer C, Zanetti L, Seitter H, Fresser F, Koschak A, Cameron AJ, Parker PJ, Baier G, Baier-Bitterlich G. Protein kinase N1 critically regulates cerebellar development and long-term function. J Clin Invest 2018; 128:2076-2088. [PMID: 29494346 PMCID: PMC5919825 DOI: 10.1172/jci96165] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 02/27/2018] [Indexed: 01/16/2023] Open
Abstract
Increasing evidence suggests that synapse dysfunctions are a major determinant of several neurodevelopmental and neurodegenerative diseases. Here we identify protein kinase N1 (PKN1) as a novel key player in fine-tuning the balance between axonal outgrowth and presynaptic differentiation in the parallel fiber-forming (PF-forming) cerebellar granule cells (Cgcs). Postnatal Pkn1-/- animals showed a defective PF-Purkinje cell (PF-PC) synapse formation. In vitro, Pkn1-/- Cgcs exhibited deregulated axonal outgrowth, elevated AKT phosphorylation, and higher levels of neuronal differentiation-2 (NeuroD2), a transcription factor preventing presynaptic maturation. Concomitantly, Pkn1-/- Cgcs had a reduced density of presynaptic sites. By inhibiting AKT with MK-2206 and siRNA-mediated knockdown, we found that AKT hyperactivation is responsible for the elongated axons, higher NeuroD2 levels, and reduced density of presynaptic specifications in Pkn1-/- Cgcs. In line with our in vitro data, Pkn1-/- mice showed AKT hyperactivation, elevated NeuroD2 levels, and reduced expression of PF-PC synaptic markers during stages of PF maturation in vivo. The long-term effect of Pkn1 knockout was further seen in cerebellar atrophy and mild ataxia. In summary, our results demonstrate that PKN1 functions as a developmentally active gatekeeper of AKT activity, thereby fine-tuning axonal outgrowth and presynaptic differentiation of Cgcs and subsequently the correct PF-PC synapse formation.
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Affiliation(s)
| | | | - Christoph Schwarzer
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Lucia Zanetti
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Hartwig Seitter
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Friedrich Fresser
- Department for Pharmacology and Genetics, Division of Translational Cell Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Alexandra Koschak
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Angus J.M. Cameron
- Kinase Biology Laboratory, John Vane Science Centre, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Peter J. Parker
- Francis Crick Institute, London, United Kingdom
- Division of Cancer Studies, King’s College London, London, United Kingdom
| | - Gottfried Baier
- Department for Pharmacology and Genetics, Division of Translational Cell Genetics, Medical University of Innsbruck, Innsbruck, Austria
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11
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Chami M, Halmer R, Schnoeder L, Anne Becker K, Meier C, Fassbender K, Gulbins E, Walter S. Acid sphingomyelinase deficiency enhances myelin repair after acute and chronic demyelination. PLoS One 2017; 12:e0178622. [PMID: 28582448 PMCID: PMC5459450 DOI: 10.1371/journal.pone.0178622] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [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: 02/13/2017] [Accepted: 05/16/2017] [Indexed: 11/19/2022] Open
Abstract
The cuprizone animal model, also known as the toxic demyelination model, is a well-reproducible model of demyelination- and remyelination in mice, and has been useful in studying important aspect of human demyelinating diseases, including multiple sclerosis. In this study, we investigated the role of acid sphingomyelinase in demyelination and myelin repair by inducing acute and chronic demyelination with 5- or 12-week cuprizone treatment, followed by a 2-week cuprizone withdrawal phase to allow myelin repair. Sphingolipids, in particular ceramide and the enzyme acid sphingomyelinase, which generates ceramide from sphingomyelin, seem to be involved in astrocyte activation and neuronal damage in multiple sclerosis. We used immunohistochemistry to study glial reaction and oligodendrocyte distribution in acid sphingomyelinase deficient mice and wild-type C57BL/6J littermates at various time intervals after demyelination and remyelination. Axonal injury was quantified using amyloid precursor protein and synaptophysin, and gene expression and protein levels were measured using gene analysis and Western blotting, respectively. Our results show that mice lacking acid sphingomyelinase had a significant increase in myelin recovery and a significantly higher oligodendrocyte cell count after 2 weeks remyelination compared to wild-type littermates. Detrimental astroglial distribution was also significantly reduced in acid sphingomyelinase deficient animals. We obtained similar results in experiments using amitriptyline to inhibit acid sphingomyelinase. These findings suggest that acid sphingomyelinase plays a significant role in myelin repair, and its inhibition by amitriptyline may constitute a novel therapeutic approach for multiple sclerosis patients.
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Affiliation(s)
- Marwan Chami
- Department of Neurology, Saarland University Hospital, Homburg, Germany
- * E-mail:
| | - Ramona Halmer
- Department of Neurology, Saarland University Hospital, Homburg, Germany
| | - Laura Schnoeder
- Department of Neurology, Saarland University Hospital, Homburg, Germany
| | - Katrin Anne Becker
- Department of Molecular Biology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Carola Meier
- Institute of Anatomy and Cell Biology, Saarland University, Homburg, Germany
| | - Klaus Fassbender
- Department of Neurology, Saarland University Hospital, Homburg, Germany
| | - Erich Gulbins
- Department of Molecular Biology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
- Department of Surgery, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Silke Walter
- Department of Neurology, Saarland University Hospital, Homburg, Germany
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
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12
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Pakavathkumar P, Noël A, Lecrux C, Tubeleviciute-Aydin A, Hamel E, Ahlfors JE, LeBlanc AC. Caspase vinyl sulfone small molecule inhibitors prevent axonal degeneration in human neurons and reverse cognitive impairment in Caspase-6-overexpressing mice. Mol Neurodegener 2017; 12:22. [PMID: 28241839 PMCID: PMC5329948 DOI: 10.1186/s13024-017-0166-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 02/22/2017] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The activation of the aspartate-specific cysteinyl protease, Caspase-6, is proposed as an early pathogenic event of Alzheimer disease (AD) and Huntington's disease. Caspase-6 inhibitors could be useful against these neurodegenerative diseases but most Caspase-6 inhibitors have been exclusively studied in vitro or show acute liver toxicity in humans. Here, we assessed vinyl sulfone small molecule peptide caspase inhibitors for potential use in vivo. METHODS The IC50 of NWL vinyl sulfone small molecule caspase inhibitors were determined on Caspase-1 to 10, and Caspase-6-transfected human colon carcinoma HCT116 cells. Inhibition of Caspase-6-mediated axonal degeneration was assessed in serum-deprived or amyloid precursor protein-transfected primary human CNS neurons. Cellular toxicity was measured by phase contrast microscopy, mitochondrial and lactate dehydrogenase colorimetric activity assays, or flow cytometry. Caspase inhibition was measured by fluorogenic activity assays, fluorescence microscopy, and western blot analyses. The effect of inhibitors on age-dependent cognitive deficits in Caspase-6 transgenic mice was assessed by the novel object recognition task. Liquid chromatography coupled to tandem mass spectrometry assessed the blood-brain barrier permeability of inhibitors in Caspase-6 mice. RESULTS Vinyl sulfone NWL-117 caspase inhibitor has a higher selectivity against Caspase-6, -4, -8, -9, and -10 whereas NWL-154 has higher selectivity against Caspase-6, -8, and -10. The half-maximal inhibitory concentrations (IC50) of NWL-117 and NWL-154 is 192 nM and 100 nM against Caspase-6 in vitro, and 4.82 μM and 3.63 μM in Caspase-6-transfected HCT116 cells, respectively. NWL inhibitors are not toxic to HCT116 cells or to human primary neurons. NWL-117 and NWL-154 inhibit serum deprivation-induced Caspase-6 activity and prevent amyloid precursor protein-mediated neurite degeneration in human primary CNS neurons. NWL-117 crosses the blood brain barrier and reverses age-dependent episodic memory deficits in Caspase-6 mice. CONCLUSIONS NWL peptidic vinyl methyl sulfone inhibitors are potent, non-toxic, blood-brain barrier permeable, and irreversible caspase inhibitors with neuroprotective effects in HCT116 cells, in primary human CNS neurons, and in Caspase-6 mice. These results highlight the therapeutic potential of vinyl sulfone inhibitors as caspase inhibitors against neurodegenerative diseases and sanction additional work to improve their selectivity against different caspases.
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Affiliation(s)
- Prateep Pakavathkumar
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, 3999 Ch. Cote Ste-Catherine, Montreal, QC, H3T 1E2, Canada
- Department of Neurology and Neurosurgery, McGill University, 845 Sherbrooke O, Montreal, QC, H3A 0G4, Canada
| | - Anastasia Noël
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, 3999 Ch. Cote Ste-Catherine, Montreal, QC, H3T 1E2, Canada
- Department of Neurology and Neurosurgery, McGill University, 845 Sherbrooke O, Montreal, QC, H3A 0G4, Canada
| | - Clotilde Lecrux
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, 3801 University Street, Montreal, QC, H3A 2B4, Canada
| | - Agne Tubeleviciute-Aydin
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, 3999 Ch. Cote Ste-Catherine, Montreal, QC, H3T 1E2, Canada
- Department of Neurology and Neurosurgery, McGill University, 845 Sherbrooke O, Montreal, QC, H3A 0G4, Canada
| | - Edith Hamel
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, 3801 University Street, Montreal, QC, H3A 2B4, Canada
| | - Jan-Eric Ahlfors
- New World Laboratories, 500 Boulevard Cartier Ouest, Laval, QC, H7V 5B7, Canada
| | - Andrea C LeBlanc
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, 3999 Ch. Cote Ste-Catherine, Montreal, QC, H3T 1E2, Canada.
- Department of Neurology and Neurosurgery, McGill University, 845 Sherbrooke O, Montreal, QC, H3A 0G4, Canada.
- Molecular and Regenerative Medicine Axis, Lady Davis Institute for Medical Research, Sir Mortimer B Davis Jewish General Hospital, 3755 ch. Côte Ste-Catherine, Montréal, QC, H3T 1E2, Canada.
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13
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Gervasi NM, Scott SS, Aschrafi A, Gale J, Vohra SN, MacGibeny MA, Kar AN, Gioio AE, Kaplan BB. The local expression and trafficking of tyrosine hydroxylase mRNA in the axons of sympathetic neurons. RNA 2016; 22:883-95. [PMID: 27095027 PMCID: PMC4878614 DOI: 10.1261/rna.053272.115] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 03/01/2016] [Indexed: 05/06/2023]
Abstract
Synthesis and regulation of catecholamine neurotransmitters in the central nervous system are implicated in the pathogenesis of a number of neuropsychiatric disorders. To identify factors that regulate the presynaptic synthesis of catecholamines, we tested the hypothesis that the rate-limiting enzyme of the catecholamine biosynthetic pathway, tyrosine hydroxylase (TH), is locally synthesized in axons and presynaptic nerve terminals of noradrenergic neurons. To isolate pure axonal mRNA and protein, rat superior cervical ganglion sympathetic neurons were cultured in compartmentalized Campenot chambers. qRT-PCR and RNA in situ hybridization analyses showed that TH mRNA is present in distal axons. Colocalization experiments with nerve terminal marker proteins suggested that both TH mRNA and protein localize in regions of the axon that resemble nerve terminals (i.e., synaptic boutons). Analysis of polysome-bound RNA showed that TH mRNA is present in polysomes isolated from distal axons. Metabolic labeling of axonally synthesized proteins labeled with the methionine analog, L-azidohomoalanine, showed that TH is locally synthesized in axons. Moreover, the local transfection and translation of exogenous TH mRNA into distal axons facilitated axonal dopamine synthesis. Finally, using chimeric td-Tomato-tagged constructs, we identified a sequence element within the TH 3'UTR that is required for the axonal localization of the reporter mRNA. Taken together, our results provide the first direct evidence that TH mRNA is trafficked to the axon and that the mRNA is locally translated. These findings raise the interesting possibility that the biosynthesis of the catecholamine neurotransmitters is locally regulated in the axon and/or presynaptic nerve terminal.
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Affiliation(s)
- Noreen M Gervasi
- Laboratory of Molecular Biology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Shane S Scott
- Laboratory of Molecular Biology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Armaz Aschrafi
- Laboratory of Molecular Biology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jenna Gale
- Laboratory of Molecular Biology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Sanah N Vohra
- Laboratory of Molecular Biology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Margaret A MacGibeny
- Laboratory of Molecular Biology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Amar N Kar
- Laboratory of Molecular Biology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Anthony E Gioio
- Laboratory of Molecular Biology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Barry B Kaplan
- Laboratory of Molecular Biology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
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14
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Islam MA, Sharif SR, Lee H, Moon IS. N-Acetyl-D-Glucosamine Kinase Promotes the Axonal Growth of Developing Neurons. Mol Cells 2015; 38:876-85. [PMID: 26467288 PMCID: PMC4625069 DOI: 10.14348/molcells.2015.0120] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 08/03/2015] [Accepted: 08/05/2015] [Indexed: 01/01/2023] Open
Abstract
N-acetyl-D-glucosamine kinase (NAGK) plays an enzyme activity-independent, non-canonical role in the dendritogenesis of hippocampal neurons in culture. In this study, we investigated its role in axonal development. We found NAGK was distributed throughout neurons until developmental stage 3 (axonal outgrowth), and that its axonal expression remarkably decreased during stage 4 (dendritic outgrowth) and became negligible in stage 5 (mature). Immunocytochemistry (ICC) showed colocalization of NAGK with tubulin in hippocampal neurons and with Golgi in somata, dendrites, and nascent axons. A proximity ligation assay (PLA) for NAGK and Golgi marker protein followed by ICC for tubulin or dynein light chain roadblock type 1 (DYNLRB1) in stage 3 neurons showed NAGK-Golgi complex colocalized with DYNLRB1 at the tips of microtubule (MT) fibers in axonal growth cones and in somatodendritic areas. PLAs for NAGK-dynein combined with tubulin or Golgi ICC showed similar signal patterns, indicating a three way interaction between NAGK, dynein, and Golgi in growing axons. In addition, overexpression of the NAGK gene and of kinase mutant NAGK genes increased axonal lengths, and knockdown of NAGK by small hairpin (sh) RNA reduced axonal lengths; suggesting a structural role for NAGK in axonal growth. Finally, transfection of 'DYNLRB1 (74-96)', a small peptide derived from DYNLRB1's C-terminal, which binds with NAGK, resulted in neurons with shorter axons in culture. The authors suggest a NAGK-dynein-Golgi tripartite interaction in growing axons is instrumental during early axonal development.
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Affiliation(s)
- Md. Ariful Islam
- Department of Anatomy, College of Medicine Dongguk University, Gyeongju 780-714,
Korea
| | - Syeda Ridita Sharif
- Department of Anatomy, College of Medicine Dongguk University, Gyeongju 780-714,
Korea
| | - HyunSook Lee
- Dongguk Medical Institute, College of Medicine Dongguk University, Gyeongju 780-714,
Korea
| | - Il Soo Moon
- Department of Anatomy, College of Medicine Dongguk University, Gyeongju 780-714,
Korea
- Dongguk Medical Institute, College of Medicine Dongguk University, Gyeongju 780-714,
Korea
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15
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Abstract
Neurons have developed elaborate mechanisms for sorting of proteins to their destination in dendrites and axons as well as dynamic local trafficking. Recent evidence suggests that polarized axonal sorting of β-site converting enzyme 1 (BACE1), a type I transmembrane aspartyl protease involved in Alzheimer's disease (AD) pathogenesis, entails an unusual journey. In hippocampal neurons, BACE1 internalized from dendrites is conveyed in recycling endosomes via unidirectional retrograde transport towards the soma and sorted to axons where BACE1 becomes enriched. In comparison to other transmembrane proteins that undergo transcytosis or elimination in somatodendritic compartment, vectorial transport of internalized BACE1 in dendrites is unique and intriguing. Dysfunction of protein transport contributes to pathogenesis of AD and other neurodegenerative diseases. Therefore, characterization of BACE1 transcytosis is an important addition to the multiple lines of evidence that highlight the crucial role played by endosomal trafficking pathway as well as axonal sorting mechanisms in AD pathogenesis.
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Affiliation(s)
- Virginie Buggia-Prévot
- Departments of Neurobiology, Neurology, and Pathology, The University of Chicago, Chicago, IL 60637
| | - Gopal Thinakaran
- Departments of Neurobiology, Neurology, and Pathology, The University of Chicago, Chicago, IL 60637
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16
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Janssen A, Fiebiger S, Bros H, Hertwig L, Romero-Suarez S, Hamann I, Chanvillard C, Bellmann-Strobl J, Paul F, Millward JM, Infante-Duarte C. Treatment of Chronic Experimental Autoimmune Encephalomyelitis with Epigallocatechin-3-Gallate and Glatiramer Acetate Alters Expression of Heme-Oxygenase-1. PLoS One 2015; 10:e0130251. [PMID: 26114502 PMCID: PMC4482710 DOI: 10.1371/journal.pone.0130251] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [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: 09/25/2014] [Accepted: 05/18/2015] [Indexed: 01/17/2023] Open
Abstract
We previously demonstrated that epigallocatechin-3-gallate (EGCG) synergizes with the immunomodulatory agent glatiramer acetate (GA) in eliciting anti-inflammatory and neuroprotective effects in the relapsing-remitting EAE model. Thus, we hypothesized that mice with chronic EAE may also benefit from this combination therapy. We first assessed how a treatment with a single dose of GA together with daily application of EGCG may modulate EAE. Although single therapies with a suboptimal dose of GA or EGCG led to disease amelioration and reduced CNS inflammation, the combination therapy had no effects. While EGCG appeared to preserve axons and myelin, the single GA dose did not improve axonal damage or demyelination. Interestingly, the neuroprotective effect of EGCG was abolished when GA was applied in combination. To elucidate how a single dose of GA may interfere with EGCG, we focused on the anti-inflammatory, iron chelating and anti-oxidant properties of EGCG. Surprisingly, we observed that while EGCG induced a downregulation of the gene expression of heme oxygenase-1 (HO-1) in affected CNS areas, the combined therapy of GA+EGCG seems to promote an increased HO-1 expression. These data suggest that upregulation of HO-1 may contribute to diminish the neuroprotective benefits of EGCG alone in this EAE model. Altogether, our data indicate that neuroprotection by EGCG in chronic EAE may involve regulation of oxidative processes, including downmodulation of HO-1. Further investigation of the re-dox balance in chronic neuroinflammation and in particular functional studies on HO-1 are warranted to understand its role in disease progression.
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Affiliation(s)
- Antonia Janssen
- Institute for Medical Immunology, Charité—Universitätmedizin Berlin, Berlin, Germany
- Experimental and Clinical Research Center, joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Sebastian Fiebiger
- Institute for Medical Immunology, Charité—Universitätmedizin Berlin, Berlin, Germany
- Experimental and Clinical Research Center, joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Helena Bros
- Institute for Medical Immunology, Charité—Universitätmedizin Berlin, Berlin, Germany
- Experimental and Clinical Research Center, joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
- NeuroCure Clinical Research Center, Charité—Universitätmedizin Berlin, Berlin, Germany
| | - Laura Hertwig
- Institute for Medical Immunology, Charité—Universitätmedizin Berlin, Berlin, Germany
- Experimental and Clinical Research Center, joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Silvina Romero-Suarez
- Institute for Medical Immunology, Charité—Universitätmedizin Berlin, Berlin, Germany
- Experimental and Clinical Research Center, joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Isabell Hamann
- Institute for Medical Immunology, Charité—Universitätmedizin Berlin, Berlin, Germany
- Experimental and Clinical Research Center, joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Coralie Chanvillard
- Institute for Medical Immunology, Charité—Universitätmedizin Berlin, Berlin, Germany
- Experimental and Clinical Research Center, joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Judith Bellmann-Strobl
- Experimental and Clinical Research Center, joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
- NeuroCure Clinical Research Center, Charité—Universitätmedizin Berlin, Berlin, Germany
- Department of Neurology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Friedemann Paul
- Experimental and Clinical Research Center, joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
- NeuroCure Clinical Research Center, Charité—Universitätmedizin Berlin, Berlin, Germany
- Department of Neurology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Jason M. Millward
- Institute for Medical Immunology, Charité—Universitätmedizin Berlin, Berlin, Germany
- Experimental and Clinical Research Center, joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Carmen Infante-Duarte
- Institute for Medical Immunology, Charité—Universitätmedizin Berlin, Berlin, Germany
- Experimental and Clinical Research Center, joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
- * E-mail:
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17
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Xiao WD, Yu AX, Liu DL. Fasudil hydrochloride could promote axonal growth through inhibiting the activity of ROCK. Int J Clin Exp Pathol 2014; 7:5564-5568. [PMID: 25337198 PMCID: PMC4203169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Accepted: 08/23/2014] [Indexed: 06/04/2023]
Abstract
OBJECTIVE This study aims to investigate the neuroprotective effect of Rho kinase inhibitor fasudil hydrochloride in ischemia/reperfusion injury N2a neuron. METHODS In vitro, N2a cells induced by ischemia and ischemia-reperfusion were treated with fasudil hydrochloride, cell damage was analyzed by MTT. On the other hand, the cytoskeleton of N2a cells was scanned through immunofluorescence techniques by Confocal Laser Microscopy which stained with FITC-phalloidin for F-actin visualization. RESULTS The activation of ROCK-II increased significantly in the damaged local during the following phase of ischemia/reperfusion injury. Ischemia induced a striking reorganization of actin cytoskeleton with a weakening of fluorescent intensity of the peripheral filament actin bands and formation of the long and thick stress fibers, but pretreatment of Fasudil hydrochloride could reversed the changes of ultra-structure on the cellular surface. MTT assay showed that Fasudil hydrochloride could prolong the survival time of the N2a cells after mimic ischemia-reperfusion for 24 h. CONCLUSIONS The activation of ROCK-II has an exceptional hoist after ischemia/reperfusion injury, it is likely to induce the collapse of the growth cone through MLC-P. Fasudil hydrochloride could promote axonal growth on inhibitory of ROCK activity.
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Affiliation(s)
- Wei-Dong Xiao
- Department of Orthopedics, Zhongnan Hospital of Wuhan University Wuhan 430071, Hubei, P. R. China
| | - Ai-Xi Yu
- Department of Orthopedics, Zhongnan Hospital of Wuhan University Wuhan 430071, Hubei, P. R. China
| | - Dan-Li Liu
- Department of Orthopedics, Zhongnan Hospital of Wuhan University Wuhan 430071, Hubei, P. R. China
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18
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Pfeiffer-Guglielmi B, Dombert B, Jablonka S, Hausherr V, van Thriel C, Schöbel N, Jansen RP. Axonal and dendritic localization of mRNAs for glycogen-metabolizing enzymes in cultured rodent neurons. BMC Neurosci 2014; 15:70. [PMID: 24898526 PMCID: PMC4079165 DOI: 10.1186/1471-2202-15-70] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 05/30/2014] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Localization of mRNAs encoding cytoskeletal or signaling proteins to neuronal processes is known to contribute to axon growth, synaptic differentiation and plasticity. In addition, a still increasing spectrum of mRNAs has been demonstrated to be localized under different conditions and developing stages thus reflecting a highly regulated mechanism and a role of mRNA localization in a broad range of cellular processes. RESULTS Applying fluorescence in-situ-hybridization with specific riboprobes on cultured neurons and nervous tissue sections, we investigated whether the mRNAs for two metabolic enzymes, namely glycogen synthase (GS) and glycogen phosphorylase (GP), the key enzymes of glycogen metabolism, may also be targeted to neuronal processes. If it were so, this might contribute to clarify the so far enigmatic role of neuronal glycogen. We found that the mRNAs for both enzymes are localized to axonal and dendritic processes in cultured lumbar spinal motoneurons, but not in cultured trigeminal neurons. In cultured cortical neurons which do not store glycogen but nevertheless express glycogen synthase, the GS mRNA is also subject to axonal and dendritic localization. In spinal motoneurons and trigeminal neurons in situ, however, the mRNAs could only be demonstrated in the neuronal somata but not in the nerves. CONCLUSIONS We could demonstrate that the mRNAs for major enzymes of neural energy metabolism can be localized to neuronal processes. The heterogeneous pattern of mRNA localization in different culture types and developmental stages stresses that mRNA localization is a versatile mechanism for the fine-tuning of cellular events. Our findings suggest that mRNA localization for enzymes of glycogen metabolism could allow adaptation to spatial and temporal energy demands in neuronal events like growth, repair and synaptic transmission.
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Affiliation(s)
- Brigitte Pfeiffer-Guglielmi
- Interfaculty Institute for Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, D-72076 Tübingen, Germany
| | - Benjamin Dombert
- Institute for Clinical Neurobiology, University of Würzburg, Würzburg, Germany
| | - Sibylle Jablonka
- Institute for Clinical Neurobiology, University of Würzburg, Würzburg, Germany
| | - Vanessa Hausherr
- Leibniz Research Center for Working Environment and Human Factors, Dortmund, Germany
| | - Christoph van Thriel
- Leibniz Research Center for Working Environment and Human Factors, Dortmund, Germany
| | - Nicole Schöbel
- Department of Cell Physiology, University of Bochum, Bochum, Germany
| | - Ralf-Peter Jansen
- Interfaculty Institute for Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, D-72076 Tübingen, Germany
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19
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Berta T, Park CK, Xu ZZ, Xie RG, Liu T, Lü N, Liu YC, Ji RR. Extracellular caspase-6 drives murine inflammatory pain via microglial TNF-α secretion. J Clin Invest 2014; 124:1173-86. [PMID: 24531553 DOI: 10.1172/jci72230] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 12/11/2013] [Indexed: 12/23/2022] Open
Abstract
Increasing evidence indicates that the pathogenesis of neuropathic pain is mediated through spinal cord microglia activation. The intracellular protease caspase-6 (CASP6) is known to regulate neuronal apoptosis and axonal degeneration; however, the contribution of microglia and CASP6 in modulating synaptic transmission and pain is unclear. Here, we found that CASP6 is expressed specifically in C-fiber axonal terminals in the superficial spinal cord dorsal horn. Animals exposed to intraplantar formalin or bradykinin injection exhibited CASP6 activation in the dorsal horn. Casp6-null mice had normal baseline pain, but impaired inflammatory pain responses. Furthermore, formalin-induced second-phase pain was suppressed by spinal injection of CASP6 inhibitor or CASP6-neutralizing antibody, as well as perisciatic nerve injection of CASP6 siRNA. Recombinant CASP6 (rCASP6) induced marked TNF-α release in microglial cultures, and most microglia within the spinal cord expressed Tnfa. Spinal injection of rCASP6 elicited TNF-α production and microglia-dependent pain hypersensitivity. Evaluation of excitatory postsynaptic currents (EPSCs) revealed that rCASP6 rapidly increased synaptic transmission in spinal cord slices via TNF-α release. Interestingly, the microglial inhibitor minocycline suppressed rCASP6 but not TNF-α-induced synaptic potentiation. Finally, rCASP6-activated microglial culture medium increased EPSCs in spinal cord slices via TNF-α. Together, these data suggest that CASP6 released from axonal terminals regulates microglial TNF-α secretion, synaptic plasticity, and inflammatory pain.
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20
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Harrison BJ, Flight RM, Gomes C, Venkat G, Ellis SR, Sankar U, Twiss JL, Rouchka EC, Petruska JC. IB4-binding sensory neurons in the adult rat express a novel 3' UTR-extended isoform of CaMK4 that is associated with its localization to axons. J Comp Neurol 2014; 522:308-36. [PMID: 23817991 PMCID: PMC3855891 DOI: 10.1002/cne.23398] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [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: 12/07/2012] [Revised: 06/13/2013] [Accepted: 06/19/2013] [Indexed: 01/22/2023]
Abstract
Calcium/calmodulin-dependent protein kinase 4 (gene and transcript: CaMK4; protein: CaMKIV) is the nuclear effector of the Ca(2+) /calmodulin kinase (CaMK) pathway where it coordinates transcriptional responses. However, CaMKIV is present in the cytoplasm and axons of subpopulations of neurons, including some sensory neurons of the dorsal root ganglia (DRG), suggesting an extranuclear role for this protein. We observed that CaMKIV was expressed strongly in the cytoplasm and axons of a subpopulation of small-diameter DRG neurons, most likely cutaneous nociceptors by virtue of their binding the isolectin IB4. In IB4+ spinal nerve axons, 20% of CaMKIV was colocalized with the endocytic marker Rab7 in axons that highly expressed CAM-kinase-kinase (CAMKK), an upstream activator of CaMKIV, suggesting a role for CaMKIV in signaling though signaling endosomes. Using fluorescent in situ hybridization (FISH) with riboprobes, we also observed that small-diameter neurons expressed high levels of a novel 3' untranslated region (UTR) variant of CaMK4 mRNA. Using rapid amplification of cDNA ends (RACE), reverse-transcription polymerase chain reaction (RT-PCR) with gene-specific primers, and cDNA sequencing analyses we determined that the novel transcript contains an additional 10 kb beyond the annotated gene terminus to a highly conserved alternate polyadenylation site. Quantitative PCR (qPCR) analyses of fluorescent-activated cell sorted (FACS) DRG neurons confirmed that this 3'-UTR-extended variant was preferentially expressed in IB4-binding neurons. Computational analyses of the 3'-UTR sequence predict that UTR-extension introduces consensus sites for RNA-binding proteins (RBPs) including the embryonic lethal abnormal vision (ELAV)/Hu family proteins. We consider the possible implications of axonal CaMKIV in the context of the unique properties of IB4-binding DRG neurons.
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Affiliation(s)
- Benjamin J. Harrison
- Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky, 40202, USA
- Kentucky Spinal Cord Injury Research Center (KSCIRC), University of Louisville, Louisville, Kentucky, 40292, USA
| | - Robert M. Flight
- Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky, 40202, USA
| | - Cynthia Gomes
- Department of Biochemistry and Molecular Bi ology, University of Louisville School of Medicine, Kentucky, 40202, USA
| | - Gayathri Venkat
- Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky, 40202, USA
- Kentucky Spinal Cord Injury Research Center (KSCIRC), University of Louisville, Louisville, Kentucky, 40292, USA
| | - Steven R Ellis
- Department of Biochemistry and Molecular Bi ology, University of Louisville School of Medicine, Kentucky, 40202, USA
| | - Uma Sankar
- James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky, 40292, USA
- Owensboro Cancer Research Program, University of Louisville, Owensboro, KY 42303, USA
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky, 40292, USA
| | - Jeffery L. Twiss
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, 19104, USA
| | - Eric C. Rouchka
- Department of Computer Engineering and Computer Science, University of Louisville, Louisville, Kentucky, 40292, USA
| | - Jeffrey C. Petruska
- Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky, 40202, USA
- Kentucky Spinal Cord Injury Research Center (KSCIRC), University of Louisville, Louisville, Kentucky, 40292, USA
- Department of Neurological Surgery, University of Louisville, Louisville, Kentucky, 40202, USA
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21
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Li X, Persad ARL, Monckton EA, Godbout R. Transcription factor AP-2delta regulates the expression of polysialyltransferase ST8SIA2 in chick retina. FEBS Lett 2014; 588:770-5. [PMID: 24462686 DOI: 10.1016/j.febslet.2014.01.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [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: 12/12/2013] [Revised: 01/07/2014] [Accepted: 01/10/2014] [Indexed: 11/17/2022]
Abstract
The AP-2δ transcription factor is restricted to a subset of retinal ganglion cells. Overexpression of AP-2δ in chick retina results in induction of polysialylated neural cell adhesion molecule (PSA-NCAM) accompanied by misrouting and bundling of ganglion cell axons. Two polysialyltransferases, ST8SIA2 and ST8SIA4, are responsible for polysialylation of NCAM. Here, we investigate the mechanism driving the increase in PSA-NCAM observed upon AP-2δ overexpression. We show that ST8SIA2 is induced by AP-2δ overexpression in chick retina. We use chromatin immunoprecipitation and gel shift assays to demonstrate direct interaction between AP-2δ and the ST8SIA2 promoter. We propose that up-regulation of ST8SIA2 upon AP-2δ overexpression in retina increases ectopic polysialylation of NCAM which in turn causes premature bundling of axons and alters axonal response to guidance cues.
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Affiliation(s)
- Xiaodong Li
- Department of Oncology, University of Alberta, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada
| | - Amit R L Persad
- Department of Oncology, University of Alberta, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada
| | - Elizabeth A Monckton
- Department of Oncology, University of Alberta, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada
| | - Roseline Godbout
- Department of Oncology, University of Alberta, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada.
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22
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Seira O, Del Río JA. Glycogen synthase kinase 3 beta (GSK3β) at the tip of neuronal development and regeneration. Mol Neurobiol 2013; 49:931-44. [PMID: 24158777 DOI: 10.1007/s12035-013-8571-y] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 10/10/2013] [Indexed: 12/31/2022]
Abstract
Gaining a basic understanding of the inhibitory molecules and the intracellular signaling involved in axon development and repulsion after neural lesions is of clear biomedical interest. In recent years, numerous studies have described new molecules and intracellular mechanisms that impair axonal outgrowth after injury. In this scenario, the role of glycogen synthase kinase 3 beta (GSK3β) in the axonal responses that occur after central nervous system (CNS) lesions began to be elucidated. GSK3β function in the nervous tissue is associated with neural development, neuron polarization, and, more recently, neurodegeneration. In fact, GSK3β has been considered as a putative therapeutic target for promoting functional recovery in injured or degenerative CNS. In this review, we summarize current understanding of the role of GSK3β during neuronal development and regeneration. In particular, we discuss GSK3β activity levels and their possible impact on cytoskeleton dynamics during both processes.
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Affiliation(s)
- Oscar Seira
- Molecular and Cellular Neurobiotechnology, Institute of Bioengineering of Catalonia (IBEC), University of Barcelona, Baldiri Reixac 15-21, 08028, Barcelona, Spain,
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23
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Sui T, Ge Y, Liu W, Zhao ZK, Zhang N, Cao X. An acetylcholinesterase antibody-based quartz crystal microbalance for the rapid identification of spinal ventral and dorsal roots. PLoS One 2013; 8:e69049. [PMID: 23935920 PMCID: PMC3720868 DOI: 10.1371/journal.pone.0069049] [Citation(s) in RCA: 6] [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: 03/15/2013] [Accepted: 06/03/2013] [Indexed: 11/26/2022] Open
Abstract
Differences in the levels of acetylcholinesterase (AChE) in ventral and dorsal spinal roots can be used to differentiate the spinal nerves. Although many methods are available to assay AChE, a rapid and sensitive method has not been previously developed. Here, we describe an antibody-based quartz crystal microbalance (QCM) assay and its application for the quantification of AChE in the solutions of ventral and dorsal spinal roots. The frequency variation of the QCM device corresponds to the level of AChE over a wide dynamic range (0.5-10 µg/ml), which is comparable to the response range of the ELISA method. The frequency shift caused by the ventral roots is 3-fold greater than that caused by the dorsal roots. The antibody-based QCM sensor was stable across many successive replicate samples, and the method required less than 10 min, including the AChE extraction and analysis steps. This method is a rapid and convenient means for the quantification of AChE in biological samples and may be applicable for distinguishing the ventral and dorsal roots during surgical operations.
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Affiliation(s)
- Tao Sui
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, People’s Republic of China
| | - Yingbin Ge
- Department of Physiology, Nanjing Medical University, Nanjing, People’s Republic of China
| | - Wujun Liu
- Division of Biotechnology, Dalian Institute of Chemical Physics, CAS, Dalian, People’s Republic of China
| | - Zongbao K. Zhao
- Division of Biotechnology, Dalian Institute of Chemical Physics, CAS, Dalian, People’s Republic of China
| | - Ning Zhang
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, People’s Republic of China
| | - Xiaojian Cao
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, People’s Republic of China
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24
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Xiong X, Hao Y, Sun K, Li J, Li X, Mishra B, Soppina P, Wu C, Hume RI, Collins CA. The Highwire ubiquitin ligase promotes axonal degeneration by tuning levels of Nmnat protein. PLoS Biol 2012; 10:e1001440. [PMID: 23226106 PMCID: PMC3514318 DOI: 10.1371/journal.pbio.1001440] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [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: 05/22/2012] [Accepted: 10/24/2012] [Indexed: 11/18/2022] Open
Abstract
Highwire, a conserved axonal E3 ubiquitin ligase, regulates the initiation of axonal degeneration after injury in Drosophila by regulating the levels of the NAD+ biosynthetic enzyme, Nmnat, and the Wnd kinase. Axonal degeneration is a hallmark of many neuropathies, neurodegenerative diseases, and injuries. Here, using a Drosophila injury model, we have identified a highly conserved E3 ubiquitin ligase, Highwire (Hiw), as an important regulator of axonal and synaptic degeneration. Mutations in hiw strongly inhibit Wallerian degeneration in multiple neuron types and developmental stages. This new phenotype is mediated by a new downstream target of Hiw: the NAD+ biosynthetic enzyme nicotinamide mononucleotide adenyltransferase (Nmnat), which acts in parallel to a previously known target of Hiw, the Wallenda dileucine zipper kinase (Wnd/DLK) MAPKKK. Hiw promotes a rapid disappearance of Nmnat protein in the distal stump after injury. An increased level of Nmnat protein in hiw mutants is both required and sufficient to inhibit degeneration. Ectopically expressed mouse Nmnat2 is also subject to regulation by Hiw in distal axons and synapses. These findings implicate an important role for endogenous Nmnat and its regulation, via a conserved mechanism, in the initiation of axonal degeneration. Through independent regulation of Wnd/DLK, whose function is required for proximal axons to regenerate, Hiw plays a central role in coordinating both regenerative and degenerative responses to axonal injury. Axons degenerate after injury and during neurodegenerative diseases, but we are still searching for the cellular mechanism responsible for this degeneration. Here, using a nerve crush injury assay in the fruit fly Drosophila, we have identified a role for a conserved molecule named Highwire (Hiw) in the initiation of axonal degeneration. Hiw is an E3 ubiquitin ligase thought to regulate the levels of specific downstream proteins by targeting their destruction. We show that Hiw promotes axonal degeneration by regulating two independent downstream targets: the Wallenda (Wnd) kinase, and the NAD+ biosynthetic enzyme nicotinamide mononucleotide adenyltransferase (Nmnat). Interestingly, Nmnat has previously been implicated in a protective role in neurons. Our findings indicate that Nmnat protein is down-regulated in axons by Hiw and that this regulation plays a critical role in the degeneration of axons and synapses. The other target, the Wnd kinase, was previously known for its role in promoting new axonal growth after injury. We propose that Hiw coordinates multiple responses to regenerate damaged neuronal circuits after injury: degeneration of the distal axon via Nmnat, and new growth of the proximal axon via Wnd.
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Affiliation(s)
- Xin Xiong
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Yan Hao
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Kan Sun
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jiaxing Li
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Xia Li
- Neuroscience Center for Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Bibhudatta Mishra
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Pushpanjali Soppina
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Chunlai Wu
- Neuroscience Center for Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Richard I. Hume
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Catherine A. Collins
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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25
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Hicks AN, Lorenzetti D, Gilley J, Lu B, Andersson KE, Miligan C, Overbeek PA, Oppenheim R, Bishop CE. Nicotinamide mononucleotide adenylyltransferase 2 (Nmnat2) regulates axon integrity in the mouse embryo. PLoS One 2012; 7:e47869. [PMID: 23082226 PMCID: PMC3474723 DOI: 10.1371/journal.pone.0047869] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [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: 03/27/2012] [Accepted: 09/24/2012] [Indexed: 12/04/2022] Open
Abstract
Using transposon-mediated gene-trap mutagenesis, we have generated a novel mouse mutant termed Blad (Bloated Bladder). Homozygous mutant mice die perinatally showing a greatly distended bladder, underdeveloped diaphragm and a reduction in total skeletal muscle mass. Wild type and heterozygote mice appear normal. Using PCR, we identified a transposon insertion site in the first intron of Nmnat2 (Nicotinamide mononucleotide adenyltransferase 2). Nmnat2 is expressed predominantly in the brain and nervous system and has been linked to the survival of axons. Expression of this gene is undetectable in Nmnat2blad/blad mutants. Examination of the brains of E18.5 Nmnat2blad/blad mutant embryos did not reveal any obvious morphological changes. In contrast, E18.5 Nmnat2blad/blad homozygotes showed an approximate 60% reduction of spinal motoneurons in the lumbar region and a more than 80% reduction in the sensory neurons of the dorsal root ganglion (DRG). In addition, facial motoneuron numbers were severely reduced, and there was virtually a complete absence of axons in the hind limb. Our observations suggest that during embryogenesis, Nmnat2 plays an important role in axonal growth or maintenance. It appears that in the absence of Nmnat2, major target organs and tissues (e.g., muscle) are not functionally innervated resulting in perinatal lethality. In addition, neither Nmnat1 nor 3 can compensate for the loss of Nmnat2. Whilst there have been recent suggestions that Nmnat2 may be an endogenous modulator of axon integrity, this work represents the first in vivo study demonstrating that Nmnat2 is involved in axon development or survival in a mammal.
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Affiliation(s)
- Amy N Hicks
- Wake Forest Institute for Regenerative Medicine, Wake Forest University, Winston Salem, North Carolina, USA.
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26
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Astorga G, Härtel S, Sanhueza M, Bacigalupo J. TRP, TRPL and cacophony channels mediate Ca2+ influx and exocytosis in photoreceptors axons in Drosophila. PLoS One 2012; 7:e44182. [PMID: 22952921 PMCID: PMC3432082 DOI: 10.1371/journal.pone.0044182] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [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: 04/16/2012] [Accepted: 08/02/2012] [Indexed: 01/17/2023] Open
Abstract
In Drosophila photoreceptors Ca(2+)-permeable channels TRP and TRPL are the targets of phototransduction, occurring in photosensitive microvilli and mediated by a phospholipase C (PLC) pathway. Using a novel Drosophila brain slice preparation, we studied the distribution and physiological properties of TRP and TRPL in the lamina of the visual system. Immunohistochemical images revealed considerable expression in photoreceptors axons at the lamina. Other phototransduction proteins are also present, mainly PLC and protein kinase C, while rhodopsin is absent. The voltage-dependent Ca(2+) channel cacophony is also present there. Measurements in the lamina with the Ca(2+) fluorescent protein G-CaMP ectopically expressed in photoreceptors, revealed depolarization-induced Ca(2+) increments mediated by cacophony. Additional Ca(2+) influx depends on TRP and TRPL, apparently functioning as store-operated channels. Single synaptic boutons resolved in the lamina by FM4-64 fluorescence revealed that vesicle exocytosis depends on cacophony, TRP and TRPL. In the PLC mutant norpA bouton labeling was also impaired, implicating an additional modulation by this enzyme. Internal Ca(2+) also contributes to exocytosis, since this process was reduced after Ca(2+)-store depletion. Therefore, several Ca(2+) pathways participate in photoreceptor neurotransmitter release: one is activated by depolarization and involves cacophony; this is complemented by internal Ca(2+) release and the activation of TRP and TRPL coupled to Ca(2+) depletion of internal reservoirs. PLC may regulate the last two processes. TRP and TRPL would participate in two different functions in distant cellular regions, where they are opened by different mechanisms. This work sheds new light on the mechanism of neurotransmitter release in tonic synapses of non-spiking neurons.
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Affiliation(s)
- Guadalupe Astorga
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
- Millennium Institute for Cell Dynamics and Biotechnology, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Steffen Härtel
- Laboratory for Scientific Image Analysis, (SCIAN-Lab), Biomedical Neuroscience Institute (BNI), ICBM, Program of Anatomy and Developmental Biology, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Magdalena Sanhueza
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
- Millennium Institute for Cell Dynamics and Biotechnology, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Juan Bacigalupo
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
- Millennium Institute for Cell Dynamics and Biotechnology, Faculty of Sciences, University of Chile, Santiago, Chile
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Zhu X, Libby RT, de Vries WN, Smith RS, Wright DL, Bronson RT, Seburn KL, John SWM. Mutations in a P-type ATPase gene cause axonal degeneration. PLoS Genet 2012; 8:e1002853. [PMID: 22912588 PMCID: PMC3415440 DOI: 10.1371/journal.pgen.1002853] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 06/07/2012] [Indexed: 01/13/2023] Open
Abstract
Neuronal loss and axonal degeneration are important pathological features of many neurodegenerative diseases. The molecular mechanisms underlying the majority of axonal degeneration conditions remain unknown. To better understand axonal degeneration, we studied a mouse mutant wabbler-lethal (wl). Wabbler-lethal (wl) mutant mice develop progressive ataxia with pronounced neurodegeneration in the central and peripheral nervous system. Previous studies have led to a debate as to whether myelinopathy or axonopathy is the primary cause of neurodegeneration observed in wl mice. Here we provide clear evidence that wabbler-lethal mutants develop an axonopathy, and that this axonopathy is modulated by Wlds and Bax mutations. In addition, we have identified the gene harboring the disease-causing mutations as Atp8a2. We studied three wl alleles and found that all result from mutations in the Atp8a2 gene. Our analysis shows that ATP8A2 possesses phosphatidylserine translocase activity and is involved in localization of phosphatidylserine to the inner leaflet of the plasma membrane. Atp8a2 is widely expressed in the brain, spinal cord, and retina. We assessed two of the mutant alleles of Atp8a2 and found they are both nonfunctional for the phosphatidylserine translocase activity. Thus, our data demonstrate for the first time that mutation of a mammalian phosphatidylserine translocase causes axon degeneration and neurodegenerative disease. Axonal degeneration is an important pathological feature of many neurodegenerative diseases, such as Alzheimer disease, Parkinson's disease, and amyotrophic lateral sclerosis. In most of these disease conditions, molecular mechanisms of axonal degeneration remain largely unknown. Spontaneous mouse mutants are important in human disease studies. Identification of a disease-causing gene in mice can lead to the identification of the human ortholog as the disease gene in humans. This approach has the power to identify unexpected genes and pathways involved in disease. Our study centered on wabbler lethal (wl) mutant mice, which display axonal degeneration in both the central and peripheral nervous systems. We identified the disease-causing gene in mice with different wl mutations. The mutations are in Atp8a2, a gene encoding a phosphatidylserine translocase. This protein functions to keep phosphatidylserine enriched to the inner leaflet of the plasma membrane. Our study demonstrates a new role for phospholipid asymmetry in maintaining axon health, and it also reveals a novel function for phosphatidyleserine translocase in neurodegenerative diseases.
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Affiliation(s)
- Xianjun Zhu
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
- The Howard Hughes Medical Institute, Bar Harbor, Maine, United States of America
| | - Richard T. Libby
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Wilhelmine N. de Vries
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
- The Howard Hughes Medical Institute, Bar Harbor, Maine, United States of America
| | - Richard S. Smith
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
- The Howard Hughes Medical Institute, Bar Harbor, Maine, United States of America
| | - Dana L. Wright
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | | | - Kevin L. Seburn
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Simon W. M. John
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
- The Howard Hughes Medical Institute, Bar Harbor, Maine, United States of America
- Department of Ophthalmology, Tufts University of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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Guo D, Standley C, Bellve K, Fogarty K, Bao ZZ. Protein kinase Cα and integrin-linked kinase mediate the negative axon guidance effects of Sonic hedgehog. Mol Cell Neurosci 2012; 50:82-92. [PMID: 22521536 PMCID: PMC3383945 DOI: 10.1016/j.mcn.2012.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [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: 09/10/2011] [Revised: 03/22/2012] [Accepted: 03/26/2012] [Indexed: 01/22/2023] Open
Abstract
In addition to its role as a morphogen, Sonic hedgehog (Shh) has also been shown to function as a guidance factor that directly acts on the growth cones of various types of axons. However, the noncanonical signaling pathways that mediate the guidance effects of Shh protein remain poorly understood. We demonstrate that a novel signaling pathway consisting of protein kinase Cα (PKCα) and integrin-linked kinase (ILK) mediates the negative guidance effects of high concentration of Shh on retinal ganglion cell (RGC) axons. Shh rapidly increased Ca(2+) level and activated PKCα and ILK in the growth cones of RGC axons. By in vitro kinase assay, PKCα was found to directly phosphorylate ILK on threonine-173 and -181. Inhibition of PKCα or expression of a mutant ILK with the PKCα phosphorylation sites mutated (ILK-DM), abolished the Shh-induced macropinocytosis, growth cone collapse and repulsive axon turning. In vivo, expression of a dominant negative PKCα or ILK-DM disrupted RGC axon pathfinding at the optic chiasm but not the projection toward the optic disk, supporting that this signaling pathway plays a specific role in Shh-mediated negative guidance effects.
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Affiliation(s)
- Daorong Guo
- Department of Medicine and Cell Biology, Program in Neuroscience, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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Abstract
Akt is a member of the AGC kinase family and consists of three isoforms. As one of the major regulators of the class I PI3 kinase pathway, it has a key role in the control of cell metabolism, growth, and survival. Although it has been extensively studied in the nervous system, we have only a faint knowledge of the specific role of each isoform in differentiated neurons. Here, we have used both cortical and hippocampal neuronal cultures to analyse their function. We characterized the expression and function of Akt isoforms, and some of their substrates along different stages of neuronal development using a specific shRNA approach to elucidate the involvement of each isoform in neuron viability, axon development, and cell signalling. Our results suggest that three Akt isoforms show substantial compensation in many processes. However, the disruption of Akt2 and Akt3 significantly reduced neuron viability and axon length. These changes correlated with a tendency to increase in active caspase 3 and a decrease in the phosphorylation of some elements of the mTORC1 pathway. Indeed, the decrease of Akt2 and more evident the inhibition of Akt3 reduced the expression and phosphorylation of S6. All these data indicate that Akt2 and Akt3 specifically regulate some aspects of apoptosis and cell growth in cultured neurons and may contribute to the understanding of mechanisms of neuron death and pathologies that show deregulated growth.
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Affiliation(s)
- Hector Diez
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) and Centro de Biología Molecular “Severo Ochoa", CSIC-UAM, Univ. Autonoma de Madrid, Madrid, Spain
| | - Juan Jose Garrido
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) and Centro de Biología Molecular “Severo Ochoa", CSIC-UAM, Univ. Autonoma de Madrid, Madrid, Spain
- Laboratory of Neuronal Polarity, Department of Molecular, Cellular and Developmental Neurobiology, Instituto Cajal, CSIC, Madrid, Spain
| | - Francisco Wandosell
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) and Centro de Biología Molecular “Severo Ochoa", CSIC-UAM, Univ. Autonoma de Madrid, Madrid, Spain
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Fang Y, Soares L, Teng X, Geary M, Bonini NM. A novel Drosophila model of nerve injury reveals an essential role of Nmnat in maintaining axonal integrity. Curr Biol 2012; 22:590-5. [PMID: 22425156 DOI: 10.1016/j.cub.2012.01.065] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 01/11/2012] [Accepted: 01/30/2012] [Indexed: 01/19/2023]
Abstract
Axons damaged by acute injury, toxic insults, or during neurodegenerative diseases undergo Wallerian or Wallerian-like degeneration, which is an active and orderly cellular process, but the underlying mechanisms are poorly understood. Drosophila has been proven to be a successful system for modeling human neurodegenerative diseases. In this study, we established a novel in vivo model of axon injury using the adult fly wing. The wing nerve highlighted by fluorescent protein markers can be directly visualized in living animals and be precisely severed by a simple wing cut, making it highly suitable for large-scale screening. Using this model, we confirmed an axonal protective function of Wld(S) and nicotinamide mononucleotide adenylyltransferase (Nmnat). We further revealed that knockdown of endogenous Nmnat triggered spontaneous, dying-back axon degeneration in vivo. Intriguingly, axonal mitochondria were rapidly depleted upon axotomy or downregulation of Nmnat. The injury-induced mitochondrial loss was dramatically suppressed by upregulation of Nmnat, which also protected severed axons from degeneration. However, when mitochondria were genetically eliminated from axons, upregulation of Nmnat was no longer effective to suppress axon degeneration. Together, these findings demonstrate an essential role of endogenous Nmnat in maintaining axonal integrity that may rely on and function by stabilizing mitochondria.
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Affiliation(s)
- Yanshan Fang
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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Gualdoni S, Albertinazzi C, Corbetta S, Valtorta F, de Curtis I. Normal levels of Rac1 are important for dendritic but not axonal development in hippocampal neurons. Biol Cell 2012; 99:455-64. [PMID: 17428196 DOI: 10.1042/bc20060119] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND INFORMATION Rho family GTPases are required for cytoskeletal reorganization and are considered important for the maturation of neurons. Among these proteins, Rac1 is known to play a crucial role in the regulation of actin dynamics, and a number of studies indicate the involvement of this protein in different steps of vertebrate neuronal maturation. There are two distinct Rac proteins expressed in neurons, namely the ubiquitous Rac1 and the neuron-specific Rac3. The specific functions of each of these GTPases during early neuronal development are largely unknown. RESULTS The combination of the knockout of Rac3 with Rac1 down-regulation by siRNA (small interfering RNA) has been used to show that down-regulation of Rac1 affects dendritic development in mouse hippocampal neurons, without affecting axons. F-actin levels are strongly decreased in neuronal growth cones following down-regulation of Rac1, and time-lapse analysis indicated that the reduction of Rac1 levels decreases growth-cone dynamics. CONCLUSIONS These results show that normal levels of endogenous Rac1 activity are critical for early dendritic development, whereas dendritic outgrowth is not affected in hippocampal neurons from Rac3-null mice. On the other hand, early axonal development appears normal after Rac1 down-regulation. Our findings also suggest that the initial establishment of neuronal polarity is not affected by Rac1 down-regulation.
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Affiliation(s)
- Sara Gualdoni
- Dibit, San Raffaele Scientific Institute, Milano, Italy
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Abstract
We provide information and protocols for the analysis of Rho GTPase function in axon pathfinding in Caenorhabditis elegans. The powerful molecular, genetic, imaging, and transgenic tools available in C. elegans make it an excellent system in which to study the in vivo roles of Rho GTPases. Methods for imaging of axon morphology in Rho GTPase single and double mutants are provided, as well as methods for the construction of transgenic C. elegans strains carrying exogenously introduced transgenes that drive the expression of constitutively active and dominant negative mutants.
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Affiliation(s)
- Jamie K Alan
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, USA
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Vaccari I, Dina G, Tronchère H, Kaufman E, Chicanne G, Cerri F, Wrabetz L, Payrastre B, Quattrini A, Weisman LS, Meisler MH, Bolino A. Genetic interaction between MTMR2 and FIG4 phospholipid phosphatases involved in Charcot-Marie-Tooth neuropathies. PLoS Genet 2011; 7:e1002319. [PMID: 22028665 PMCID: PMC3197679 DOI: 10.1371/journal.pgen.1002319] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [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: 04/06/2011] [Accepted: 08/09/2011] [Indexed: 01/01/2023] Open
Abstract
We previously reported that autosomal recessive demyelinating Charcot-Marie-Tooth (CMT) type 4B1 neuropathy with myelin outfoldings is caused by loss of MTMR2 (Myotubularin-related 2) in humans, and we created a faithful mouse model of the disease. MTMR2 dephosphorylates both PtdIns3P and PtdIns(3,5)P(2), thereby regulating membrane trafficking. However, the function of MTMR2 and the role of the MTMR2 phospholipid phosphatase activity in vivo in the nerve still remain to be assessed. Mutations in FIG4 are associated with CMT4J neuropathy characterized by both axonal and myelin damage in peripheral nerve. Loss of Fig4 function in the plt (pale tremor) mouse produces spongiform degeneration of the brain and peripheral neuropathy. Since FIG4 has a role in generation of PtdIns(3,5)P(2) and MTMR2 catalyzes its dephosphorylation, these two phosphatases might be expected to have opposite effects in the control of PtdIns(3,5)P(2) homeostasis and their mutations might have compensatory effects in vivo. To explore the role of the MTMR2 phospholipid phosphatase activity in vivo, we generated and characterized the Mtmr2/Fig4 double null mutant mice. Here we provide strong evidence that Mtmr2 and Fig4 functionally interact in both Schwann cells and neurons, and we reveal for the first time a role of Mtmr2 in neurons in vivo. Our results also suggest that imbalance of PtdIns(3,5)P(2) is at the basis of altered longitudinal myelin growth and of myelin outfolding formation. Reduction of Fig4 by null heterozygosity and downregulation of PIKfyve both rescue Mtmr2-null myelin outfoldings in vivo and in vitro.
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Affiliation(s)
- Ilaria Vaccari
- Human Inherited Neuropathies Unit, INSPE-Institute for Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
- Dulbecco Telethon Institute, San Raffaele Scientific Institute, Milan, Italy
| | - Giorgia Dina
- Neuropathology Unit, INSPE–Institute for Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Hélène Tronchère
- INSERM U1048 and Université Toulouse 3, I2MC, CHU Toulouse, Toulouse, France
| | - Emily Kaufman
- Biology of Myelin Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Gaëtan Chicanne
- INSERM U1048 and Université Toulouse 3, I2MC, CHU Toulouse, Toulouse, France
| | - Federica Cerri
- Neuropathology Unit, INSPE–Institute for Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Lawrence Wrabetz
- Biology of Myelin Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Bernard Payrastre
- INSERM U1048 and Université Toulouse 3, I2MC, CHU Toulouse, Toulouse, France
| | - Angelo Quattrini
- Neuropathology Unit, INSPE–Institute for Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Lois S. Weisman
- Life Science Institute, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Miriam H. Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Alessandra Bolino
- Human Inherited Neuropathies Unit, INSPE-Institute for Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
- Dulbecco Telethon Institute, San Raffaele Scientific Institute, Milan, Italy
- * E-mail:
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Lumb JH, Connell JW, Allison R, Reid E. The AAA ATPase spastin links microtubule severing to membrane modelling. Biochim Biophys Acta 2011; 1823:192-7. [PMID: 21888932 DOI: 10.1016/j.bbamcr.2011.08.010] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 08/10/2011] [Accepted: 08/17/2011] [Indexed: 11/18/2022]
Abstract
In 1999, mutations in the gene encoding the microtubule severing AAA ATPase spastin were identified as a major cause of a genetic neurodegenerative condition termed hereditary spastic paraplegia (HSP). This finding stimulated intense study of the spastin protein and over the last decade, a combination of cell biological, in vivo, in vitro and structural studies have provided important mechanistic insights into the cellular functions of the protein, as well as elucidating cell biological pathways that might be involved in axonal maintenance and degeneration. Roles for spastin have emerged in shaping the endoplasmic reticulum and the abscission stage of cytokinesis, in which spastin appears to couple membrane modelling to microtubule regulation by severing.
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Affiliation(s)
- Jennifer H Lumb
- Department of Medical Genetics and Cambridge Institute for Medical Research, University of Cambridge, UK
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35
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Huff TB, Shi Y, Sun W, Wu W, Shi R, Cheng JX. Real-time CARS imaging reveals a calpain-dependent pathway for paranodal myelin retraction during high-frequency stimulation. PLoS One 2011; 6:e17176. [PMID: 21390223 PMCID: PMC3048389 DOI: 10.1371/journal.pone.0017176] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 01/24/2011] [Indexed: 11/21/2022] Open
Abstract
High-frequency electrical stimulation is becoming a promising therapy for neurological disorders, however the response of the central nervous system to stimulation remains poorly understood. The current work investigates the response of myelin to electrical stimulation by laser-scanning coherent anti-Stokes Raman scattering (CARS) imaging of myelin in live spinal tissues in real time. Paranodal myelin retraction at the nodes of Ranvier was observed during 200 Hz electrical stimulation. Retraction was seen to begin minutes after the onset of stimulation and continue for up to 10 min after stimulation was ceased, but was found to reverse after a 2 h recovery period. The myelin retraction resulted in exposure of Kv 1.2 potassium channels visualized by immunofluorescence. Accordingly, treating the stimulated tissue with a potassium channel blocker, 4-aminopyridine, led to the appearance of a shoulder peak in the compound action potential curve. Label-free CARS imaging of myelin coupled with multiphoton fluorescence imaging of immuno-labeled proteins at the nodes of Ranvier revealed that high-frequency stimulation induced paranodal myelin retraction via pathologic calcium influx into axons, calpain activation, and cytoskeleton degradation through spectrin break-down.
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Affiliation(s)
- Terry B. Huff
- Department of Chemistry, Purdue University, West Lafayette, Indiana, United States of America
| | - Yunzhou Shi
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Wenjing Sun
- Department of Basic Medical Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Wei Wu
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Riyi Shi
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
- Department of Basic Medical Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Ji-Xin Cheng
- Department of Chemistry, Purdue University, West Lafayette, Indiana, United States of America
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
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Zhao Q, Gao J, Li W, Cai D. Neurotrophic and neurorescue effects of Echinacoside in the subacute MPTP mouse model of Parkinson's disease. Brain Res 2010; 1346:224-36. [PMID: 20478277 DOI: 10.1016/j.brainres.2010.05.018] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 05/01/2010] [Accepted: 05/04/2010] [Indexed: 12/29/2022]
Abstract
Many experiments support the notion that augmentation of neurotrophic factors' (NTFs) activity, especially glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) could prevent or halt the progress of neurodegeneration in Parkinson's disease (PD). However, application of NTFs as therapeutic agents for PD is hampered by the difficulty in delivering them to specific brain regions safely and effectively. Another potential strategy is to stimulate the endogenous expression of NTFs. In this study, we investigated the effects of Echinacoside (ECH), a monomer extracted from herbs, on rescuing dopaminergic function in 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-lesioned mice. We found that oral administration of ECH (30 mg/kg/day for 14 days) to MPTP-treated mice, commencing after impairment of the nigrstriatal system, suppressed the reduction of nigral dopaminergic neurons, striatal fibers, dopamine and dopamine transporter to 134.24%, 203.17%, 147.25% and 154.72 of MPTP-lesioned animals respectively (p<0.05). There was a relative elevation in expression of GDNF and BDNF mRNA (2.94 and 3.75-fold) and protein (184.34% and 185.93%) in ECH treated mice compared with vehicle-treated MPTP-lesioned mice (p<0.05). In addition, the apoptosis cells and Bax/Bcl-2 ratio of mRNA and protein in MPTP-lesioned mice significantly increased, and these effects could be prevented by ECH. At the 7th and 14th days of ECH treatment, the gait disorder displayed obvious improvement (p<0.05). These findings demonstrate that ECH is probably a novel, orally active, non-peptide inducer of NTFs and inhibitor of apoptosis, and they provide preclinical support for therapeutic potential of this compound in the treatment of PD.
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MESH Headings
- Animals
- Apoptosis/drug effects
- Axons/enzymology
- Blotting, Western
- Brain-Derived Neurotrophic Factor/biosynthesis
- Cell Survival/drug effects
- Chromatography, High Pressure Liquid
- Dopamine/metabolism
- Dopamine/physiology
- Gait Disorders, Neurologic/chemically induced
- Gait Disorders, Neurologic/psychology
- Glial Cell Line-Derived Neurotrophic Factor/biosynthesis
- Glycosides/therapeutic use
- Immunohistochemistry
- In Situ Nick-End Labeling
- MPTP Poisoning/drug therapy
- MPTP Poisoning/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Neostriatum/enzymology
- Nerve Growth Factors/biosynthesis
- Neurons/drug effects
- Neurons/physiology
- Parkinson Disease, Secondary/chemically induced
- Parkinson Disease, Secondary/drug therapy
- Parkinson Disease, Secondary/metabolism
- Proto-Oncogene Proteins c-bcl-2/biosynthesis
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Tyrosine 3-Monooxygenase/metabolism
- bcl-2-Associated X Protein/biosynthesis
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Affiliation(s)
- Qing Zhao
- Laboratory of Neurology, Institute of Integrative Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
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Ito Z, Sakamoto K, Imagama S, Matsuyama Y, Zhang H, Hirano K, Ando K, Yamashita T, Ishiguro N, Kadomatsu K. N-acetylglucosamine 6-O-sulfotransferase-1-deficient mice show better functional recovery after spinal cord injury. J Neurosci 2010; 30:5937-47. [PMID: 20427653 PMCID: PMC6632605 DOI: 10.1523/jneurosci.2570-09.2010] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Revised: 12/15/2009] [Accepted: 03/08/2010] [Indexed: 01/16/2023] Open
Abstract
Neurons in the adult CNS do not spontaneously regenerate after injuries. The glycosaminoglycan keratan sulfate is induced after spinal cord injury, but its biological significance is not well understood. Here we investigated the role of keratan sulfate in functional recovery after spinal cord injury, using mice deficient in N-acetylglucosamine 6-O-sulfotransferase-1 that lack 5D4-reactive keratan sulfate in the CNS. We made contusion injuries at the 10th thoracic level. Expressions of N-acetylglucosamine 6-O-sulfotransferase-1 and keratan sulfate were induced after injury in wild-type mice, but not in the deficient mice. The wild-type and deficient mice showed similar degrees of chondroitin sulfate induction and of CD11b-positive inflammatory cell recruitment. However, motor function recovery, as assessed by the footfall test, footprint test, and Basso mouse scale locomotor scoring, was significantly better in the deficient mice. Moreover, the deficient mice showed a restoration of neuromuscular system function below the lesion after electrical stimulation at the occipito-cervical area. In addition, axonal regrowth of both the corticospinal and raphespinal tracts was promoted in the deficient mice. In vitro assays using primary cerebellar granule neurons demonstrated that keratan sulfate proteoglycans were required for the proteoglycan-mediated inhibition of neurite outgrowth. These data collectively indicate that keratan sulfate expression is closely associated with functional disturbance after spinal cord injury. N-acetylglucosamine 6-O-sulfotransferase-1-deficient mice are a good model to investigate the roles of keratan sulfate in the CNS.
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Affiliation(s)
- Zenya Ito
- Departments of Biochemistry and
- Orthopedics, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | | | - Shiro Imagama
- Departments of Biochemistry and
- Orthopedics, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Yukihiro Matsuyama
- Orthopedics, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | | | - Kenichi Hirano
- Orthopedics, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Kei Ando
- Orthopedics, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan, and
| | - Naoki Ishiguro
- Orthopedics, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Kenji Kadomatsu
- Departments of Biochemistry and
- Institute for Advanced Research, Nagoya University, Nagoya 464-8601, Japan
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Pinter R, Hindges R. Perturbations of microRNA function in mouse dicer mutants produce retinal defects and lead to aberrant axon pathfinding at the optic chiasm. PLoS One 2010; 5:e10021. [PMID: 20386732 PMCID: PMC2850387 DOI: 10.1371/journal.pone.0010021] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [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: 09/04/2009] [Accepted: 03/16/2010] [Indexed: 11/19/2022] Open
Abstract
Background During development axons encounter a variety of choice points where they have to make appropriate pathfinding decisions. The optic chiasm is a major decision point for retinal ganglion cell (RGC) axons en route to their target in order to ensure the correct wiring of the visual system. MicroRNAs (miRNAs) belong to the class of small non-coding RNA molecules and have been identified as important regulators of a variety of processes during embryonic development. However, their involvement in axon guidance decisions is less clear. Methodology/Principal Findings We report here that the early loss of Dicer, an essential protein for the maturation of miRNAs, in all cells of the forming retina and optic chiasm leads to severe phenotypes of RGC axon pathfinding at the midline. Using a conditional deletion approach in mice, we find in homozygous Dicer mutants a marked increase of ipsilateral projections, RGC axons extending outside the optic chiasm, the formation of a secondary optic tract and a substantial number of RGC axons projecting aberrantly into the contralateral eye. In addition, the mutant mice display a microphthalmia phenotype. Conclusions Our work demonstrates an important role of Dicer controlling the extension of RGC axons to the brain proper. It indicates that miRNAs are essential regulatory elements for mechanisms that ensure correct axon guidance decisions at the midline and thus have a central function in the establishment of circuitry during the development of the nervous system.
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Affiliation(s)
- Rita Pinter
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Campus, London, United Kingdom
| | - Robert Hindges
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Campus, London, United Kingdom
- * E-mail:
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Chang PA, Wu YJ. Neuropathy target esterase: an essential enzyme for neural development and axonal maintenance. Int J Biochem Cell Biol 2009; 42:573-5. [PMID: 20006730 DOI: 10.1016/j.biocel.2009.12.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 12/05/2009] [Accepted: 12/07/2009] [Indexed: 11/19/2022]
Abstract
Neuropathy target esterase (NTE) is an endoplasmic reticulum-anchored protein conserved across species. The N-terminal regulatory region of NTE contains three cyclic nucleotide binding domains while the C-terminal catalytic domain has a patatin domain. The NTE gene is expressed in mouse early at embryonic day 7 and its expression is maintained throughout embryonic development. NTE protein is mainly distributed in the nervous system with a pattern that is more restricted to large neurons in older animals. NTE regulates phospholipid metabolism and is known to be a phospholipase B. Knockout of NTE is embryonic lethal in mice, indicating that NTE is essential for embryonic survival. Neuronal specific NTE knockouts survive to adulthood, but show vacuolation and neuronal loss characteristic of neurodegenerative diseases. Recently, mutations in human NTE have been shown to cause a hereditary spastic paraplegia called NTE-related motor neuron disorder, suggesting a critical role for NTE in the nervous system.
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Affiliation(s)
- Ping-An Chang
- Key Laboratory of Molecular Biology, College of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing 400065, PR China
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40
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Martinelli P, Rugarli EI. Emerging roles of mitochondrial proteases in neurodegeneration. Biochim Biophys Acta 2009; 1797:1-10. [PMID: 19664590 DOI: 10.1016/j.bbabio.2009.07.013] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Revised: 07/28/2009] [Accepted: 07/28/2009] [Indexed: 01/31/2023]
Abstract
Fine tuning of integrated mitochondrial functions is essential in neurons and rationalizes why mitochondrial dysfunction plays an important pathogenic role in neurodegeneration. Mitochondria can contribute to neuronal cell death and axonal dysfunction through a plethora of mechanisms, including low ATP levels, increased reactive oxygen species, defective calcium regulation, and impairment of dynamics and transport. Recently, mitochondrial proteases in the inner mitochondrial membrane have emerged as culprits in several human neurodegenerative diseases. Mitochondrial proteases degrade misfolded and non-assembled polypeptides, thus performing quality control surveillance in the organelle. Moreover, they regulate the activity of specific substrates by mediating essential processing steps. Mitochondrial proteases may be directly involved in neurodegenerative diseases, as recently shown for the m-AAA protease, or may regulate crucial mitochondrial molecules, such as OPA1, which in turn is implicated in human disease. The mitochondrial proteases HTRA2 and PARL increase the susceptibility of neurons to apoptotic cell death. Here we review our current knowledge on how disturbances of the mitochondrial proteolytic system affect neuronal maintenance and axonal function.
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Affiliation(s)
- Paola Martinelli
- Laboratory of Genetic and Molecular Pathology, Istituto Neurologico "C. Besta", Milan, Italy
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41
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Scales TME, Lin S, Kraus M, Goold RG, Gordon-Weeks PR. Nonprimed and DYRK1A-primed GSK3 beta-phosphorylation sites on MAP1B regulate microtubule dynamics in growing axons. J Cell Sci 2009; 122:2424-35. [PMID: 19549690 PMCID: PMC2704879 DOI: 10.1242/jcs.040162] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [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] [Accepted: 04/21/2009] [Indexed: 12/26/2022] Open
Abstract
MAP1B is a developmentally regulated microtubule-associated phosphoprotein that regulates microtubule dynamics in growing axons and growth cones. We used mass spectrometry to map 28 phosphorylation sites on MAP1B, and selected for further study a putative primed GSK3 beta site and compared it with two nonprimed GSK3 beta sites that we had previously characterised. We raised a panel of phosphospecific antibodies to these sites on MAP1B and used it to assess the distribution of phosphorylated MAP1B in the developing nervous system. This showed that the nonprimed sites are restricted to growing axons, whereas the primed sites are also expressed in the neuronal cell body. To identify kinases phosphorylating MAP1B, we added kinase inhibitors to cultured embryonic cortical neurons and monitored MAP1B phosphorylation with our panel of phosphospecific antibodies. These experiments identified dual-specificity tyrosine-phosphorylation-regulated kinase (DYRK1A) as the kinase that primes sites of GSK3 beta phosphorylation in MAP1B, and we confirmed this by knocking down DYRK1A in cultured embryonic cortical neurons by using shRNA. DYRK1A knockdown compromised neuritogenesis and was associated with alterations in microtubule stability. These experiments demonstrate that MAP1B has DYRK1A-primed and nonprimed GSK3 beta sites that are involved in the regulation of microtubule stability in growing axons.
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Affiliation(s)
- Timothy M E Scales
- The MRC Centre for Developmental Neurobiology, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
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42
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Kousaka A, Mori Y, Koyama Y, Taneda T, Miyata S, Tohyama M. The distribution and characterization of endogenous protein arginine N-methyltransferase 8 in mouse CNS. Neuroscience 2009; 163:1146-57. [PMID: 19576965 DOI: 10.1016/j.neuroscience.2009.06.061] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2009] [Revised: 06/04/2009] [Accepted: 06/27/2009] [Indexed: 11/18/2022]
Abstract
Protein arginine N-methyltransferase (PRMT) 8 was first discovered from a database search for genes harboring four conserved methyltransferase motifs, which shares more than 80% homology to PRMT1 in amino acid [Lee J, Sayegh J, Daniel J, Clarke S, Bedford MT (2005) PRMT8, a new membrane-bound tissue-specific member of the protein arginine methyltransferase family. J Biol Chem 280:32890-32896]. Interestingly, its tissue distribution is strikingly restricted to mouse CNS. To characterize the function in the CNS neurons, we raised an antiserum against PRMT8 to perform immunohistochemistry (IHC) and Western blot analysis. By IHC, the immunoreactivity of endogenous PRMT8 was broadly distributed in the CNS neurons with markedly intense signals in the cerebellum, hippocampal formation, and cortex, but was not detected in the cerebellar granular layer. In some subset of the neurons, the immunoreactivity was observed in the dendrites and axon bundles. The subcellular localization of the immunoreactivity was dominantly nuclear, arguing against the original report that exogenously expressed PRMT8 localizes to the plasma membrane via the N-terminal myristoylation. A series of the exogenously expressed proteins with different in-frame translation initiation codons was tested for comparison with the endogenous protein in molecular size. The third initiator codon produced the protein that was equivalent in size to the endogenous and showed a similar localizing pattern in PC12 cells. In conclusion, PRMT8 is a neuron-specific nuclear enzyme and the N-terminus does not contain the glycine end for myristoylation target.
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Affiliation(s)
- A Kousaka
- Department of Anatomy and Neuroscience, Graduate School of Medicine, The Osaka-Hamamatsu Joint Research Center for Child Mental Development, Osaka University, 2-2 Yamadaoka, Suita City, Osaka, Japan
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Sasaki Y, Vohra BPS, Lund FE, Milbrandt J. Nicotinamide mononucleotide adenylyl transferase-mediated axonal protection requires enzymatic activity but not increased levels of neuronal nicotinamide adenine dinucleotide. J Neurosci 2009; 29:5525-35. [PMID: 19403820 PMCID: PMC3162248 DOI: 10.1523/jneurosci.5469-08.2009] [Citation(s) in RCA: 192] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Revised: 01/07/2009] [Accepted: 01/26/2009] [Indexed: 01/15/2023] Open
Abstract
Axonal degeneration is a hallmark of many neurological disorders. Studies in animal models of neurodegenerative diseases indicate that axonal degeneration is an early event in the disease process, and delaying this process can lead to decreased progression of the disease and survival extension. Overexpression of the Wallerian degeneration slow (Wld(s)) protein can delay axonal degeneration initiated via axotomy, chemotherapeutic agents, or genetic mutations. The Wld(s) protein consists of the N-terminal portion of the ubiquitination factor Ube4b fused to the nicotinamide adenine dinucleotide (NAD(+)) biosynthetic enzyme nicotinamide mononucleotide adenylyl transferase 1 (Nmnat1). We previously showed that the Nmnat1 portion of this fusion protein was the critical moiety for Wld(s)-mediated axonal protection. Here, we describe the development of an automated quantitative assay for assessing axonal degeneration. This method successfully showed that Nmnat1 enzymatic activity is important for axonal protection as mutants with reduced enzymatic activity lacked axon protective activity. We also found that Nmnat enzymes with diverse sequences and structures from various species, including Drosophila melanogaster, Saccharomyces cerevisiae, and archaebacterium Methanocaldococcus jannaschii, which encodes a protein with no homology to eukaryotic Nmnat enzymes, all mediate robust axonal protection after axotomy. Besides the importance of Nmnat enzymatic activity, we did not observe changes in the steady-state NAD(+) level, and we found that inhibition of nicotinamide phosphoribosyltransferase (Nampt), which synthesizes substrate for Nmnat in mammalian cells, did not affect the protective activity of Nmnat1. These results provide the possibility of a role for new Nmnat enzymatic activity in axonal protection in addition to NAD(+) synthesis.
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Affiliation(s)
- Yo Sasaki
- Departments of Pathology and Immunology and
| | | | - Frances E. Lund
- Division of Allergy, Immunology, and Rheumatology, University of Rochester, Rochester, New York 14642
| | - Jeffrey Milbrandt
- Departments of Pathology and Immunology and
- Neurology and
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri 63110, and
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Yudin D, Hanz S, Yoo S, Iavnilovitch E, Willis D, Gradus T, Vuppalanchi D, Segal-Ruder Y, Ben-Yaakov K, Hieda M, Yoneda Y, Twiss JL, Fainzilber M. Localized regulation of axonal RanGTPase controls retrograde injury signaling in peripheral nerve. Neuron 2008; 59:241-52. [PMID: 18667152 DOI: 10.1016/j.neuron.2008.05.029] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Revised: 05/26/2008] [Accepted: 05/27/2008] [Indexed: 12/30/2022]
Abstract
Peripheral sensory neurons respond to axon injury by activating an importin-dependent retrograde signaling mechanism. How is this mechanism regulated? Here, we show that Ran GTPase and its associated effectors RanBP1 and RanGAP regulate the formation of importin signaling complexes in injured axons. A gradient of nuclear RanGTP versus cytoplasmic RanGDP is thought to be fundamental for the organization of eukaryotic cells. Surprisingly, we find RanGTP in sciatic nerve axoplasm, distant from neuronal cell bodies and nuclei, and in association with dynein and importin-alpha. Following injury, localized translation of RanBP1 stimulates RanGTP dissociation from importins and subsequent hydrolysis, thereby allowing binding of newly synthesized importin-beta to importin-alpha and dynein. Perturbation of RanGTP hydrolysis or RanBP1 blockade at axonal injury sites reduces the neuronal conditioning lesion response. Thus, neurons employ localized mechanisms of Ran regulation to control retrograde injury signaling in peripheral nerve.
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Affiliation(s)
- Dmitry Yudin
- Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel
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Iijima-Ando K, Hearn SA, Granger L, Shenton C, Gatt A, Chiang HC, Hakker I, Zhong Y, Iijima K. Overexpression of neprilysin reduces alzheimer amyloid-beta42 (Abeta42)-induced neuron loss and intraneuronal Abeta42 deposits but causes a reduction in cAMP-responsive element-binding protein-mediated transcription, age-dependent axon pathology, and premature death in Drosophila. J Biol Chem 2008; 283:19066-76. [PMID: 18463098 PMCID: PMC2441542 DOI: 10.1074/jbc.m710509200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2007] [Revised: 04/01/2008] [Indexed: 12/20/2022] Open
Abstract
The amyloid-beta42 (Abeta42) peptide has been suggested to play a causative role in Alzheimer disease (AD). Neprilysin (NEP) is one of the rate-limiting Abeta-degrading enzymes, and its enhancement ameliorates extracellular amyloid pathology, synaptic dysfunction, and memory defects in mouse models of Abeta amyloidosis. In addition to the extracellular Abeta, intraneuronal Abeta42 may contribute to AD pathogenesis. However, the protective effects of neuronal NEP expression on intraneuronal Abeta42 accumulation and neurodegeneration remain elusive. In contrast, sustained NEP activation may be detrimental because NEP can degrade many physiological peptides, but its consequences in the brain are not fully understood. Using transgenic Drosophila expressing human NEP and Abeta42, we demonstrated that NEP efficiently suppressed the formation of intraneuronal Abeta42 deposits and Abeta42-induced neuron loss. However, neuronal NEP overexpression reduced cAMP-responsive element-binding protein-mediated transcription, caused age-dependent axon degeneration, and shortened the life span of the flies. Interestingly, the mRNA levels of endogenous fly NEP genes and phosphoramidon-sensitive NEP activity declined during aging in fly brains, as observed in mammals. Taken together, these data suggest both the protective and detrimental effects of chronically high NEP activity in the brain. Down-regulation of NEP activity in aging brains may be an evolutionarily conserved phenomenon, which could predispose humans to developing late-onset AD.
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Affiliation(s)
- Kanae Iijima-Ando
- Laboratory of Neurogenetics and Pathobiology, Farber Institute for Neurosciences, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
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Abstract
Phosphatidylinositol 3-kinase (PI3K) activity is known to be required for the extension of embryonic sensory axons. Inhibition of PI3K has also been shown to mediate axon retraction and growth cone collapse in response to semaphorin 3A. However, the effects of inhibiting PI3K on the neuronal cytoskeleton are not well characterized. We have previously reported that semaphorin 3A-induced axon retraction involves activation of myosin II, the formation of an intra-axonal F-actin bundle cytoskeleton, and blocks the formation of F-actin patches that serve as precursors to filopodial formation in axons. We now report that inhibition of PI3K results in activation of myosin II in axons. Inhibition of myosin II activity, or its upstream regulatory kinase RhoA-kinase, blocked axon retraction induced by inhibition of PI3K. In addition, inhibition of PI3K also induced intra-axonal F-actin bundles, which likely serve as a substratum for myosin II-based force generation during axon retraction. In axons, filopodia are formed from axonal F-actin patch precursors. Analysis of axonal F-actin patch formation in eYFP-actin expressing neurons revealed that inhibition of PI3K blocked formation of axonal F-actin patches, and thus filopodial formation. These data provide insights into the regulation of the neuronal cytoskeleton by PI3K and are consistent with the notion that decreased levels of PI3K activity mediate axon retraction and growth cone collapse in response to semaphorin 3A.
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Affiliation(s)
- Irina Orlova
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA
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48
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Suto F. [Semaphorin/plexin signal regulates lamina-restricted projection of hippocampal mossy fiber]. Tanpakushitsu Kakusan Koso 2008; 53:469-474. [PMID: 21089322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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49
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Kurusu M, Zinn K. Receptor tyrosine phosphatases regulate birth order-dependent axonal fasciculation and midline repulsion during development of the Drosophila mushroom body. Mol Cell Neurosci 2008; 38:53-65. [PMID: 18356078 DOI: 10.1016/j.mcn.2008.01.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Revised: 01/18/2008] [Accepted: 01/25/2008] [Indexed: 01/05/2023] Open
Abstract
Receptor tyrosine phosphatases (RPTPs) are required for axon guidance during embryonic development in Drosophila. Here we examine the roles of four RPTPs during development of the larval mushroom body (MB). MB neurons extend axons into parallel tracts known as the peduncle and lobes. The temporal order of neuronal birth is reflected in the organization of axons within these tracts. Axons of the youngest neurons, known as core fibers, extend within a single bundle at the center, while those of older neurons fill the outer layers. RPTPs are selectively expressed on the core fibers of the MB. Ptp10D and Ptp69D regulate segregation of the young axons into a single core bundle. Ptp69D signaling is required for axonal extension beyond the peduncle. Lar and Ptp69D are necessary for the axonal branching decisions that create the lobes. Avoidance of the brain midline by extending medial lobe axons involves signaling through Lar.
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Affiliation(s)
- Mitsuhiko Kurusu
- Broad Center, Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
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50
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Ichikawa M, Yoshida J, Saito K, Sagawa H, Tokita Y, Watanabe M. Differential effects of two ROCK inhibitors, Fasudil and Y-27632, on optic nerve regeneration in adult cats. Brain Res 2008; 1201:23-33. [PMID: 18313036 DOI: 10.1016/j.brainres.2008.01.063] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 01/23/2008] [Accepted: 01/24/2008] [Indexed: 11/19/2022]
Abstract
A ROCK inhibitor Fasudil is widely administered to relieve vasospasm in patients after subarachnoid hemorrhage in Japan. We investigated the difference of Fasudil and Y-27632, a common ROCK inhibitor, on neurite regeneration in culture and axonal regeneration after injuring the optic nerve (OpN) in cats. The optimal dose of Y-27632, determined by counting the number and length of neurites in retinal explants, was found to be 100 microM: the only effect of Fasudil was to promote extension of glial processes. We next examined the effects of Fasudil (10 microM-100 microM) and Y-27632 (10 microM-300 microM) on axonal regeneration in the crushed OpN model in vivo. Immediately after crushing the left OpN, Fasudil or Y-27632 was injected into the vitreous and the crushed site. Injection of 10 microM and 100 microM Y-27632 induced extension of the optic axons beyond the crush site, with the latter dosage giving stronger regeneration. Very few axons passed beyond the crush site in the optic nerve with phosphate-buffered saline injection, and no axons elongated in the OpN with Fasudil injection.
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Affiliation(s)
- Masahiro Ichikawa
- Department of Neurosurgery, Nagoya University Graduate School of Medicine, Tsuruma-cho, Showa-ku, Nagoya, Aichi 466-8550, Japan
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