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Walters JM, Noblet HA, Chung HJ. An emerging role of STriatal-Enriched protein tyrosine Phosphatase in hyperexcitability-associated brain disorders. Neurobiol Dis 2024; 200:106641. [PMID: 39159894 DOI: 10.1016/j.nbd.2024.106641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2024] [Revised: 08/15/2024] [Accepted: 08/16/2024] [Indexed: 08/21/2024] Open
Abstract
STriatal-Enriched protein tyrosine Phosphatase (STEP) is a brain-specific tyrosine phosphatase that is associated with numerous neurological and neuropsychiatric disorders. STEP dephosphorylates and inactivates various kinases and phosphatases critical for neuronal function and health including Fyn, Pyk2, ERK1/2, p38, and PTPα. Importantly, STEP dephosphorylates NMDA and AMPA receptors, two major glutamate receptors that mediate fast excitatory synaptic transmission. This STEP-mediated dephosphorylation leads to their internalization and inhibits both Hebbian synaptic potentiation and homeostatic synaptic scaling. Hence, STEP has been widely accepted to weaken excitatory synaptic strength. However, emerging evidence implicates a novel role of STEP in neuronal hyperexcitability and seizure disorders. Genetic deletion and pharmacological blockade of STEP reduces seizure susceptibility in acute seizure mouse models and audiogenic seizures in a mouse model of Fragile X syndrome. Pharmacologic inhibition of STEP also decreases hippocampal activity and neuronal intrinsic excitability. Here, we will highlight the divergent roles of STEP in excitatory synaptic transmission and neuronal intrinsic excitability, present the potential underlying mechanisms, and discuss their impact on STEP-associated neurologic and neuropsychiatric disorders.
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Affiliation(s)
- Jennifer M Walters
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Hayden A Noblet
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Hee Jung Chung
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Institute of Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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Mahaman YAR, Huang F, Embaye KS, Wang X, Zhu F. The Implication of STEP in Synaptic Plasticity and Cognitive Impairments in Alzheimer's Disease and Other Neurological Disorders. Front Cell Dev Biol 2021; 9:680118. [PMID: 34195199 PMCID: PMC8236946 DOI: 10.3389/fcell.2021.680118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 05/06/2021] [Indexed: 12/31/2022] Open
Abstract
STriatal-Enriched protein tyrosine Phosphatase (STEP) is a tyrosine phosphatase that has been implicated in Alzheimer’s disease (AD), the most common form of dementia, and many other neurological diseases. The protein level and activity of STEP have been found to be elevated in most of these disorders, and specifically in AD as a result of dysregulation of different pathways including PP2B/DARPP32/PP1, PKA as well as impairments of both proteasomal and lysosomal systems. The upregulation in STEP leads to increased binding to, and dephosphorylation of, its substrates which are mainly found to be synaptic plasticity and thus learning and memory related proteins. These proteins include kinases like Fyn, Pyk2, ERK1/2 and both NMDA and AMPA receptor subunits GluN2B and GluA2. The dephosphorylation of these molecules results in inactivation of these kinases and internalization of NMDA and AMPA receptor complexes leading to synapse loss and cognitive impairments. In this study, we aim to review STEP regulation and its implications in AD as well as other neurological disorders and then summarize data on targeting STEP as therapeutic strategy in these diseases.
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Affiliation(s)
- Yacoubou Abdoul Razak Mahaman
- Cognitive Impairment Ward of Neurology Department, The Third Affiliated Hospital, Shenzhen University, Shenzhen, China.,Department of Pathophysiology, School of Basic Medicine, Key Laboratory of Education Ministry of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Fang Huang
- Department of Pathophysiology, School of Basic Medicine, Key Laboratory of Education Ministry of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Kidane Siele Embaye
- Department of Pathophysiology, School of Basic Medicine, Key Laboratory of Education Ministry of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaochuan Wang
- Department of Pathophysiology, School of Basic Medicine, Key Laboratory of Education Ministry of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Feiqi Zhu
- Cognitive Impairment Ward of Neurology Department, The Third Affiliated Hospital, Shenzhen University, Shenzhen, China
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Telegina DV, Kulikova EA, Kozhevnikova OS, Kulikov AV, Khomenko TM, Volcho KP, Salakhutdinov NF, Kolosova NG. Alterations of STEP46 and STEP61 Expression in the Rat Retina with Age and AMD-Like Retinopathy Development. Int J Mol Sci 2020; 21:E5182. [PMID: 32707818 PMCID: PMC7432912 DOI: 10.3390/ijms21155182] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/16/2020] [Accepted: 07/20/2020] [Indexed: 12/19/2022] Open
Abstract
Tyrosine phosphatase STEP (striatal-enriched tyrosine protein phosphatase) is a brain-specific protein phosphatase and is involved in the pathogenesis of many neurodegenerative diseases. Here, we examined the impact of STEP on the development of age-related macular degeneration (AMD)-like pathology in senescence-accelerated OXYS rats. Using OXYS and Wistar rats (control), we for the first time demonstrated age-dependent changes in Ptpn5 mRNA expression, STEP46 and STEP61 protein levels, and their phosphatase activity in the retina. The increases in STEP protein levels and the decrease of total and STEP phosphatase activities in the retina (as compared with Wistar rats) preceded the manifestation of clinical signs of AMD in OXYS rats (age 20 days). There were no differences in these retinal parameters between 13-month-old Wistar rats and OXYS rats with pronounced signs of AMD. Inhibition of STEP with TC-2153 during progressive AMD-like retinopathy (from 9 to 13 months of age) reduced the thickness of the retinal inner nuclear layer, as evidenced by a decreased amount of parvalbumin-positive amacrine neurons. Prolonged treatment with TC-2153 had no effect on Ptpn5 mRNA expression, STEP46 and STEP61 protein levels, and their phosphatase activity in the OXYS retina. Thus, TC-2153 may negatively affect the retina through mechanisms unrelated to STEP.
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Affiliation(s)
- Darya V. Telegina
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (SB RAS), Pr. Lavrentyeva 10, 630090 Novosibirsk, Russia; (E.A.K.); (O.S.K.); (A.V.K.); (N.G.K.)
| | - Elizabeth A. Kulikova
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (SB RAS), Pr. Lavrentyeva 10, 630090 Novosibirsk, Russia; (E.A.K.); (O.S.K.); (A.V.K.); (N.G.K.)
| | - Oyuna S. Kozhevnikova
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (SB RAS), Pr. Lavrentyeva 10, 630090 Novosibirsk, Russia; (E.A.K.); (O.S.K.); (A.V.K.); (N.G.K.)
| | - Alexander V. Kulikov
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (SB RAS), Pr. Lavrentyeva 10, 630090 Novosibirsk, Russia; (E.A.K.); (O.S.K.); (A.V.K.); (N.G.K.)
| | - Tatyana M. Khomenko
- N.N. Vorozhtsov Institute of Organic Chemistry, SB RAS, 9 Lavrentieva Avenue, 630090 Novosibirsk, Russia; (T.M.K.); (K.P.V.); (N.F.S.)
| | - Konstantin P. Volcho
- N.N. Vorozhtsov Institute of Organic Chemistry, SB RAS, 9 Lavrentieva Avenue, 630090 Novosibirsk, Russia; (T.M.K.); (K.P.V.); (N.F.S.)
| | - Nariman F. Salakhutdinov
- N.N. Vorozhtsov Institute of Organic Chemistry, SB RAS, 9 Lavrentieva Avenue, 630090 Novosibirsk, Russia; (T.M.K.); (K.P.V.); (N.F.S.)
| | - Nataliya G. Kolosova
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (SB RAS), Pr. Lavrentyeva 10, 630090 Novosibirsk, Russia; (E.A.K.); (O.S.K.); (A.V.K.); (N.G.K.)
- N.N. Vorozhtsov Institute of Organic Chemistry, SB RAS, 9 Lavrentieva Avenue, 630090 Novosibirsk, Russia; (T.M.K.); (K.P.V.); (N.F.S.)
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Khotskin NV, Plyusnina AV, Kulikova EA, Bazhenova EY, Fursenko DV, Sorokin IE, Kolotygin I, Mormede P, Terenina EE, Shevelev OB, Kulikov AV. On association of the lethal yellow (A) mutation in the agouti gene with the alterations in mouse brain and behavior. Behav Brain Res 2019; 359:446-456. [DOI: 10.1016/j.bbr.2018.11.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 11/08/2018] [Accepted: 11/08/2018] [Indexed: 10/27/2022]
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Lombroso PJ, Ogren M, Kurup P, Nairn AC. Molecular underpinnings of neurodegenerative disorders: striatal-enriched protein tyrosine phosphatase signaling and synaptic plasticity. F1000Res 2016; 5. [PMID: 29098072 PMCID: PMC5642311 DOI: 10.12688/f1000research.8571.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/20/2016] [Indexed: 12/22/2022] Open
Abstract
This commentary focuses on potential molecular mechanisms related to the dysfunctional synaptic plasticity that is associated with neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. Specifically, we focus on the role of striatal-enriched protein tyrosine phosphatase (STEP) in modulating synaptic function in these illnesses. STEP affects neuronal communication by opposing synaptic strengthening and does so by dephosphorylating several key substrates known to control synaptic signaling and plasticity. STEP levels are elevated in brains from patients with Alzheimer's and Parkinson's disease. Studies in model systems have found that high levels of STEP result in internalization of glutamate receptors as well as inactivation of ERK1/2, Fyn, Pyk2, and other STEP substrates necessary for the development of synaptic strengthening. We discuss the search for inhibitors of STEP activity that may offer potential treatments for neurocognitive disorders that are characterized by increased STEP activity. Future studies are needed to examine the mechanisms of differential and region-specific changes in STEP expression pattern, as such knowledge could lead to targeted therapies for disorders involving disrupted STEP activity.
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Affiliation(s)
- Paul J Lombroso
- Child Study Center, Yale University School of Medicine, New Haven, Connecticut, 06520, USA.,Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, 06520, USA.,Department of Neuroscience, Yale University School of Medicine, New Haven, Connecticut, 06520, USA
| | - Marilee Ogren
- Department of Psychology, Boston College, Chestnut Hill, MA, 02467, USA
| | - Pradeep Kurup
- Child Study Center, Yale University School of Medicine, New Haven, Connecticut, 06520, USA
| | - Angus C Nairn
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, 06520, USA
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Won S, Incontro S, Nicoll RA, Roche KW. PSD-95 stabilizes NMDA receptors by inducing the degradation of STEP61. Proc Natl Acad Sci U S A 2016; 113:E4736-44. [PMID: 27457929 PMCID: PMC4987792 DOI: 10.1073/pnas.1609702113] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Phosphorylation regulates surface and synaptic expression of NMDA receptors (NMDARs). Both the tyrosine kinase Fyn and the tyrosine phosphatase striatal-enriched protein tyrosine phosphatase (STEP) are known to target the NMDA receptor subunit GluN2B on tyrosine 1472, which is a critical residue that mediates NMDAR endocytosis. STEP reduces the surface expression of NMDARs by promoting dephosphorylation of GluN2B Y1472, whereas the synaptic scaffolding protein postsynaptic density protein 95 (PSD-95) stabilizes the surface expression of NMDARs. However, nothing is known about a potential functional interaction between STEP and PSD-95. We now report that STEP61 binds to PSD-95 but not to other PSD-95 family members. We find that PSD-95 expression destabilizes STEP61 via ubiquitination and degradation by the proteasome. Using subcellular fractionation, we detect low amounts of STEP61 in the PSD fraction. However, STEP61 expression in the PSD is increased upon knockdown of PSD-95 or in vivo as detected in PSD-95-KO mice, demonstrating that PSD-95 excludes STEP61 from the PSD. Importantly, only extrasynaptic NMDAR expression and currents were increased upon STEP knockdown, as is consistent with low STEP61 localization in the PSD. Our findings support a dual role for PSD-95 in stabilizing synaptic NMDARs by binding directly to GluN2B but also by promoting synaptic exclusion and degradation of the negative regulator STEP61.
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Affiliation(s)
- Sehoon Won
- Receptor Biology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Salvatore Incontro
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, 94158
| | - Roger A Nicoll
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, 94158; Department of Physiology, University of California, San Francisco, CA, 94158
| | - Katherine W Roche
- Receptor Biology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892;
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7
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Role of Striatal-Enriched Tyrosine Phosphatase in Neuronal Function. Neural Plast 2016; 2016:8136925. [PMID: 27190655 PMCID: PMC4844879 DOI: 10.1155/2016/8136925] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/27/2016] [Indexed: 11/18/2022] Open
Abstract
Striatal-enriched protein tyrosine phosphatase (STEP) is a CNS-enriched protein implicated in multiple neurologic and neuropsychiatric disorders. STEP regulates key signaling proteins required for synaptic strengthening as well as NMDA and AMPA receptor trafficking. Both high and low levels of STEP disrupt synaptic function and contribute to learning and behavioral deficits. High levels of STEP are present in human postmortem samples and animal models of Alzheimer's disease, Parkinson's disease, and schizophrenia and in animal models of fragile X syndrome. Low levels of STEP activity are present in additional disorders that include ischemia, Huntington's chorea, alcohol abuse, and stress disorders. Thus the current model of STEP is that optimal levels are required for optimal synaptic function. Here we focus on the role of STEP in Alzheimer's disease and the mechanisms by which STEP activity is increased in this illness. Both genetic lowering of STEP levels and pharmacological inhibition of STEP activity in mouse models of Alzheimer's disease reverse the biochemical and cognitive abnormalities that are present. These findings suggest that STEP is an important point for modulation of proteins required for synaptic plasticity.
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Saavedra A, Puigdellívol M, Tyebji S, Kurup P, Xu J, Ginés S, Alberch J, Lombroso PJ, Pérez-Navarro E. BDNF Induces Striatal-Enriched Protein Tyrosine Phosphatase 61 Degradation Through the Proteasome. Mol Neurobiol 2015. [PMID: 26223799 DOI: 10.1007/s12035-015-9335-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) promotes synaptic strengthening through the regulation of kinase and phosphatase activity. Conversely, striatal-enriched protein tyrosine phosphatase (STEP) opposes synaptic strengthening through inactivation or internalization of signaling molecules. Here, we investigated whether BDNF regulates STEP levels/activity. BDNF induced a reduction of STEP61 levels in primary cortical neurons, an effect that was prevented by inhibition of tyrosine kinases, phospholipase C gamma, or the ubiquitin-proteasome system (UPS). The levels of pGluN2B(Tyr1472) and pERK1/2(Thr202/Tyr204), two STEP substrates, increased in BDNF-treated cultures, and blockade of the UPS prevented STEP61 degradation and reduced BDNF-induced GluN2B and ERK1/2 phosphorylation. Moreover, brief or sustained cell depolarization reduced STEP61 levels in cortical neurons by different mechanisms. BDNF also promoted UPS-mediated STEP61 degradation in cultured striatal and hippocampal neurons. In contrast, nerve growth factor and neurotrophin-3 had no effect on STEP61 levels. Our results thus indicate that STEP61 degradation is an important event in BDNF-mediated effects.
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Affiliation(s)
- Ana Saavedra
- Departament de Biologia Cel · lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Mar Puigdellívol
- Departament de Biologia Cel · lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Shiraz Tyebji
- Departament de Biologia Cel · lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Pradeep Kurup
- Child Study Center, Yale University School of Medicine, 230 South Frontage Road, New Haven, CT, 06520, USA
| | - Jian Xu
- Child Study Center, Yale University School of Medicine, 230 South Frontage Road, New Haven, CT, 06520, USA
| | - Silvia Ginés
- Departament de Biologia Cel · lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Jordi Alberch
- Departament de Biologia Cel · lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Paul J Lombroso
- Child Study Center, Yale University School of Medicine, 230 South Frontage Road, New Haven, CT, 06520, USA
| | - Esther Pérez-Navarro
- Departament de Biologia Cel · lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Catalonia, Spain. .,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain. .,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
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9
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Karasawa T, Lombroso PJ. Disruption of striatal-enriched protein tyrosine phosphatase (STEP) function in neuropsychiatric disorders. Neurosci Res 2014; 89:1-9. [PMID: 25218562 DOI: 10.1016/j.neures.2014.08.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 08/12/2014] [Accepted: 08/21/2014] [Indexed: 10/24/2022]
Abstract
Striatal-enriched protein tyrosine phosphatase (STEP) is a brain-specific tyrosine phosphatase that plays a major role in the development of synaptic plasticity. Recent findings have implicated STEP in several psychiatric and neurological disorders, including Alzheimer's disease, schizophrenia, fragile X syndrome, Huntington's disease, stroke/ischemia, and stress-related psychiatric disorders. In these disorders, STEP protein expression levels and activity are dysregulated, contributing to the cognitive deficits that are present. In this review, we focus on the most recent findings on STEP, discuss how STEP expression and activity are maintained during normal cognitive function, and how disruptions in STEP activity contribute to a number of illnesses.
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Affiliation(s)
- Takatoshi Karasawa
- Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi 480-0392, Japan.
| | - Paul J Lombroso
- Departments of Neurobiology, Psychiatry and Child Study Center, Yale University School of Medicine, New Haven, CT 06520, USA
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Prokosch V, Chiwitt C, Rose K, Thanos S. Deciphering proteins and their functions in the regenerating retina. Expert Rev Proteomics 2014; 7:775-95. [DOI: 10.1586/epr.10.47] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Goebel-Goody SM, Lombroso PJ. Taking STEPs forward to understand fragile X syndrome. Results Probl Cell Differ 2012; 54:223-41. [PMID: 22009355 DOI: 10.1007/978-3-642-21649-7_12] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A priority of fragile X syndrome (FXS) research is to determine the molecular mechanisms underlying the functional, behavioral, and structural deficits in humans and in the FXS mouse model. Given that metabotropic glutamate receptor (mGluR) long-term depression (LTD) is exaggerated in FXS mice, considerable effort has focused on proteins that regulate this form of synaptic plasticity. STriatal-Enriched protein tyrosine Phosphatase (STEP) is a brain-specific phosphatase implicated as an "LTD protein" because it mediates AMPA receptor internalization during mGluR LTD. STEP also promotes NMDA receptor endocytosis and inactivates ERK1/2 and Fyn, thereby opposing synaptic strengthening. We hypothesized that dysregulation of STEP may contribute to the pathophysiology of FXS. We review how STEP's expression and activity are regulated by dendritic protein synthesis, ubiquitination, proteolysis, and phosphorylation. We also discuss implications for STEP in FXS and other disorders, including Alzheimer's disease. As highlighted here, pharmacological interventions targeting STEP may prove successful for FXS.
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Goebel-Goody SM, Baum M, Paspalas CD, Fernandez SM, Carty NC, Kurup P, Lombroso PJ. Therapeutic implications for striatal-enriched protein tyrosine phosphatase (STEP) in neuropsychiatric disorders. Pharmacol Rev 2011; 64:65-87. [PMID: 22090472 DOI: 10.1124/pr.110.003053] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Striatal-enriched protein tyrosine phosphatase (STEP) is a brain-specific phosphatase that modulates key signaling molecules involved in synaptic plasticity and neuronal function. Targets include extracellular-regulated kinase 1 and 2 (ERK1/2), stress-activated protein kinase p38 (p38), the Src family tyrosine kinase Fyn, N-methyl-D-aspartate receptors (NMDARs), and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). STEP-mediated dephosphorylation of ERK1/2, p38, and Fyn leads to inactivation of these enzymes, whereas STEP-mediated dephosphorylation of surface NMDARs and AMPARs promotes their endocytosis. Accordingly, the current model of STEP function posits that it opposes long-term potentiation and promotes long-term depression. Phosphorylation, cleavage, dimerization, ubiquitination, and local translation all converge to maintain an appropriate balance of STEP in the central nervous system. Accumulating evidence over the past decade indicates that STEP dysregulation contributes to the pathophysiology of several neuropsychiatric disorders, including Alzheimer's disease, schizophrenia, fragile X syndrome, epileptogenesis, alcohol-induced memory loss, Huntington's disease, drug abuse, stroke/ischemia, and inflammatory pain. This comprehensive review discusses STEP expression and regulation and highlights how disrupted STEP function contributes to the pathophysiology of diverse neuropsychiatric disorders.
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Affiliation(s)
- Susan M Goebel-Goody
- Child Study Center, Yale University School of Medicine, New Haven, Connecticut, USA
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Schnichels S, Heiduschka P, Julien S. RGMA and neogenin protein expression are influenced by lens injury following optic nerve crush in the rat retina. Graefes Arch Clin Exp Ophthalmol 2011; 250:39-50. [PMID: 21887516 DOI: 10.1007/s00417-011-1791-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 07/14/2011] [Accepted: 07/28/2011] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND The death and the failure of neurons to regenerate their axons after lesion of the central nervous system in mammals, as in the case of spinal cord injury and optic nerve trauma, remain a challenge. In this study, we focused on the repulsive guidance molecule A (RGMA) and its receptor neogenin. Since it was reported that RGMA+ cells accumulate in lesioned areas after spinal cord injury, brain trauma, and optic nerve crush, and curiously, anti-apoptotic effects of RGMA were also described, we investigated the role of RGMA and neogenin in the retina after optic nerve crush (ONC). METHODS We evaluated the spatial and temporal protein pattern of RGMA and neogenin in the rat retina without (non-regenerating model) or with (regenerating model) lens injury (LI). We investigated the presence of RGMA, neogenin and other proteins at up to nine time points (6 h-20 days post-surgery) by performing immunohistochemistry and Western blots. RESULTS Independent of the treatment, RGMA protein was present in the nuclear layers (NLs), plexiform layers (PLs), nerve fiber layer (NFL), and in retinal ganglion cells (RGCs) of the rat retina. RGC and nerve fibers were always RGMA+. Further RGMA+ cells in the retina were blood vessel endothelial cells, astrocytes, Müller cells, and some microglial cells. The RGMA pattern for the specific retinal cells resembled those of previously published data. The neogenin pattern was congruent to the RGMA pattern. Western blots of retinal tissue showed further RGMA+ products only in LI animals. Furthermore, a higher amount of RGMA was found in the retinae of ONC + LI rats compared to ONC rats. CONCLUSIONS Although a difference in the localization of RGMA is not obvious, the difference in the amount of RGMA is striking, the higher amount of RGMA in the retinae of ONC + LI rats compared to ONC rats indicates a role for RGMA during degeneration/regeneration processes. Our results are consistent with several reported neuroprotective effects of RGMA. Our new data showing the upregulation of RGMA after ONC in our regenerating model (plus LI) confirm these findings conducted in different settings.
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Affiliation(s)
- Sven Schnichels
- Centre for Ophthalmology, University Eye Hospital, Tübingen, Germany
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Schnichels S, Heiduschka P, Julien S. Different spatial and temporal protein expressions of repulsive guidance molecule a and neogenin in the rat optic nerve after optic nerve crush with and without lens injury. J Neurosci Res 2011; 89:490-505. [DOI: 10.1002/jnr.22584] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 11/10/2010] [Accepted: 11/22/2010] [Indexed: 12/30/2022]
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15
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Sethi J, Zhao B, Cuvillier-Hot V, Boidin-Wichlacz C, Salzet M, Macagno ER, Baker MW. The receptor protein tyrosine phosphatase HmLAR1 is up-regulated in the CNS of the adult medicinal leech following injury and is required for neuronal sprouting and regeneration. Mol Cell Neurosci 2010; 45:430-8. [PMID: 20708686 DOI: 10.1016/j.mcn.2010.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 07/16/2010] [Accepted: 08/01/2010] [Indexed: 01/19/2023] Open
Abstract
LAR-like receptor protein tyrosine phosphatases (RPTPs), which are abundantly expressed in the nervous systems of most if not all bilaterian animals thus far examined, have been implicated in regulating a variety of critical neuronal processes. These include neuronal pathfinding, adhesion and synaptogenesis during development and, in adult mammals, neuronal regeneration. Here we explored a possible role of a LAR-like RPTP (HmLAR1) in response to mechanical trauma in the adult nervous system of the medicinal leech. In situ hybridization and QPCR analyses of HmLAR1 expression in individual segmental ganglia revealed a significant up-regulation in receptor expression following CNS injury, both in situ and following a period in vitro. Furthermore, we observed up-regulation in the expression of the leech homologue of the Abelson tyrosine kinase, a putative signaling partner to LAR receptors, but not among other tyrosine kinases. The effects on neuronal regeneration were assayed by comparing growth across a nerve crush by projections of individual dorsal P neurons (P(D)) following single-cell injection of interfering RNAs against the receptor or control RNAs. Receptor RNAi led to a significant reduction in HmLAR1 expression by the injected cells and resulted in a significant decrease in sprouting and regenerative growth at the crush site relative to controls. These studies extend the role of the HmLARs from leech neuronal development to adult neuronal regeneration and provide a platform to investigate neuronal regeneration and gene regulation at the single cell level.
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Affiliation(s)
- Jasmine Sethi
- Division of Biology, University of California, San Diego, CA 92093, USA
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16
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Lorber B, Berry M, Douglas MR, Nakazawa T, Logan A. Activated retinal glia promote neurite outgrowth of retinal ganglion cells via apolipoprotein E. J Neurosci Res 2010; 87:2645-52. [PMID: 19382209 DOI: 10.1002/jnr.22095] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In the present study, we investigated the role and mechanism through which activated retinal glia stimulate retinal ganglion cell (RGC) neurite outgrowth. We have found that the level of retinal glial activation correlates directly with enhanced RGC neurite outgrowth after a preconditioning intravitreal Zymosan injection. Reduction in the number of activated glia in primary rat retinal cultures led to significantly reduced RGC neurite outgrowth. Glial-related neurite outgrowth appears to be, at least in part, mediated via apolipoprotein E (ApoE), which is expressed by activated retinal astrocytes and Müller glia. ApoE-deficient mice showed significantly reduced RGC neurite outgrowth potential after intravitreal Zymosan injection compared with age-matched wild-type animals. These observations suggest that ApoE, expressed by activated retinal glia, stimulates RGC neurite outgrowth after intravitreal Zymosan injection.
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Affiliation(s)
- Barbara Lorber
- Molecular Neuroscience Group, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK
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17
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Wang X, Chen W, Liu W, Wu J, Shao Y, Zhang X. The role of thrombospondin-1 and transforming growth factor-beta after spinal cord injury in the rat. J Clin Neurosci 2009; 16:818-21. [PMID: 19342245 DOI: 10.1016/j.jocn.2008.09.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 09/15/2008] [Accepted: 09/18/2008] [Indexed: 01/08/2023]
Abstract
Spinal cord injury (SCI) continues to result in high morbidity and mortality throughout the world. An effective neuroprotective agent is still not available to counteract secondary damage caused by traumatic injury. Thrombospondin-1 (TSP-1) and transforming growth factor-beta (TGF-beta) have a role in angiogenesis, scar deposition, inflammation and may affect astrocyte phenotype and mobility. We investigated the role of TSP-1 and TGF-beta in a model of spinal cord injury in rats. Forty female Sprague-Dawley rats were randomly divided into two equal groups: the experimental group was subject to SCI using an impactor and the sham-operated group was not subject to SCI. These animals were sacrificed at 12 h and 24 h after SCI for immunochemistry and Western blot analysis of the injured spinal segment for the expression of the TSP-1 and TGF-beta proteins. We found that TSP-1 and TGF-beta expression increased immediately after SCI in the injured segment. After 12 h, TSP-1 concentrations increased more rapidly and dramatically than TGF-beta in the injured segment of the spinal cord. Elevations in TSP-1 and TGF-beta concentrations persisted for 24 h after injury. These results show that elevated expression of TSP-1 and TGF-beta can be detected in the injured segment of the spinal cord 12 and 24 h after injury. Thus, TSP-1 and TGF-beta may have a role in SCI.
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Affiliation(s)
- Xianghua Wang
- Department of Orthopedics, The Second Affiliated Hospital School of Medicine, Zhejiang University, Hangzhou, China
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18
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Lorber B, Berry M, Logan A. Different factors promote axonal regeneration of adult rat retinal ganglion cells after lens injury and intravitreal peripheral nerve grafting. J Neurosci Res 2008; 86:894-903. [PMID: 18074384 DOI: 10.1002/jnr.21545] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We have investigated the differential mediators of the neurotrophic effects of intravitreal peripheral nerve grafting and lens injury on adult rat retinal ganglion cells (RGC). Lens injury and intravitreal peripheral nerve grafting both stimulated RGC neurite growth in vitro and axon regeneration past the optic nerve lesion site in vivo concomitant with activation of retinal glia and invasion of macrophages into the eye. These observations, together with the results of coculture studies using a macrophage-free intact peripheral nerve segment, a macrophage-free intact lens, a macrophage-rich peripheral nerve segment, or a macrophage-rich injured lens in retinal cultures suggest that the stimulation of RGC axon regeneration by lens injury and intravitreal peripheral nerve grafting share a common macrophage-derived component overlain by distinct lens-derived and peripheral nerve-derived neurotrophic factors, respectively. RGC axon regeneration following lens injury and intravitreal peripheral nerve grafting was similar in vivo, correlating with similar retinal glia activation whereas, in vitro, the level of RGC neurite outgrowth was significantly higher following intravitreal peripheral nerve grafting compared with lens injury, concomitant with the presence of increased numbers of activated retinal glia. This suggests that in vivo RGC axon regeneration induced by lens injury and peripheral nerve grafting may be limited, in part, by factors derived from activated retinal glia.
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Affiliation(s)
- Barbara Lorber
- Molecular Neuroscience Group, Division of Medical Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
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19
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Kostic A, Sap J, Sheetz MP. RPTPalpha is required for rigidity-dependent inhibition of extension and differentiation of hippocampal neurons. J Cell Sci 2007; 120:3895-904. [PMID: 17940065 DOI: 10.1242/jcs.009852] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Receptor-like protein tyrosine phosphatase alpha (RPTPalpha)-knockout mice have severe hippocampal abnormalities similar to knockouts of the Src family kinase Fyn. These enzymes are linked to the matrix-rigidity response in fibroblasts, but their function in neurons is unknown. The matrix-rigidity response of fibroblasts appears to differ from that of neuronal growth cones but it is unknown whether the rigidity detection mechanism or response pathway is altered. Here, we report that RPTPalpha is required for rigidity-dependent reinforcement of fibronectin (FN)-cytoskeleton bonds and the rigidity response in hippocampal neuron growth cones, like in fibroblasts. In control neurons, rigid FN surfaces inhibit neurite extension and neuron differentiation relative to soft surfaces. In RPTPalpha(-/-) neurons, no inhibition of extension and differentiation is found on both rigid and soft surfaces. The RPTPalpha-dependent rigidity response in neurons is FN-specific, and requires clustering of alpha(v)beta(6) integrin at the leading edge of the growth cones. Further, RPTPalpha is necessary for the rigidity-dependent concentration of Fyn and p130Cas phosphorylation at the leading edge of the growth cone, like it is in fibroblasts. Although neurons respond to rigid FN surfaces in the opposite way to fibroblasts, we suggest that the mechanism of detecting FN rigidity is similar and involves rigidity-dependent RPTPalpha recruitment of Fyn.
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Affiliation(s)
- Ana Kostic
- Department of Biological Sciences, Columbia University, 1212 Amsterdam Avenue, New York, NY 10027, USA
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20
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Yang T, Massa SM, Longo FM. LAR protein tyrosine phosphatase receptor associates with TrkB and modulates neurotrophic signaling pathways. ACTA ACUST UNITED AC 2007; 66:1420-36. [PMID: 17013927 DOI: 10.1002/neu.20291] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The identities of receptor protein tyrosine phosphatases (PTPs) that associate with Trk protein tyrosine kinase (PTK) receptors and modulate neurotrophic signaling are unknown. The leukocyte common antigen-related (LAR) receptor PTP is present in neurons expressing TrkB, and like TrkB is associated with caveolae and regulates survival and neurite outgrowth. We tested the hypothesis that LAR associates with TrkB and regulates neurotrophic signaling in embryonic hippocampal neurons. Coimmunoprecipitation and coimmunostaining demonstrated LAR interaction with TrkB that is increased by BDNF exposure. BDNF neurotrophic activity was reduced in LAR-/- and LAR siRNA-treated LAR+/+ neurons and was augmented in LAR-transfected neurons. In LAR-/- neurons, BDNF-induced activation of TrkB, Shc, AKT, ERK, and CREB was significantly decreased; while in LAR-transfected neurons, BDNF-induced CREB activation was augmented. Similarly, LAR+/+ neurons treated with LAR siRNA demonstrated decreased activation of Trk and AKT. LAR is known to activate the Src PTK by dephosphorylation of its negative regulatory domain and Src transactivates Trk. In LAR-/- neurons, or neurons treated with LAR siRNA, phosphorylation of the Src regulatory domain was increased (indicating Src inactivation), consistent with a role for Src in mediating LAR's ability to up-regulate neurotrophic signaling. Interactions between LAR, TrkB, and Src were further confirmed by the findings that Src coimmunoprecipitated with LAR, that the Src inhibitor PP2 blocked the ability of LAR to augment TrkB signaling, and that siRNA-induced depletion of Src decreased LAR interaction with TrkB. These studies demonstrate that receptor PTPs can associate with Trk complexes and promote neurotrophic signaling and point to receptor PTP-based strategies as a novel approach for modulating neurotrophin function.
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MESH Headings
- Animals
- Blotting, Western/methods
- Brain-Derived Neurotrophic Factor/metabolism
- Brain-Derived Neurotrophic Factor/pharmacology
- Cell Survival/drug effects
- Cells, Cultured
- Culture Media, Conditioned/pharmacology
- Dose-Response Relationship, Drug
- Embryo, Mammalian
- Enzyme Inhibitors/pharmacology
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/genetics
- Gene Expression Regulation/physiology
- Hippocampus/cytology
- Immunoprecipitation/methods
- Mice
- Mice, Knockout
- Mutation/physiology
- Nerve Tissue Proteins/immunology
- Nerve Tissue Proteins/physiology
- Neurons/drug effects
- Neurons/metabolism
- Phosphorylation/drug effects
- Protein Tyrosine Phosphatases/chemistry
- Protein Tyrosine Phosphatases/deficiency
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/immunology
- Protein Tyrosine Phosphatases/physiology
- Pyrimidines/pharmacology
- RNA, Small Interfering/pharmacology
- Receptor, trkB/physiology
- Receptor-Like Protein Tyrosine Phosphatases, Class 2
- Receptor-Like Protein Tyrosine Phosphatases, Class 4
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/immunology
- Receptors, Cell Surface/physiology
- Signal Transduction/physiology
- Time Factors
- Transfection/methods
- Tyrosine/metabolism
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Affiliation(s)
- Tao Yang
- Department of Neurology, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina 27599, USA
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21
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Gonzalez AM, Berry M, Greenlees L, Logan A, Baird A. Matrix-mediated gene transfer to brain cortex and dorsal root ganglion neurones by retrograde axonal transport after dorsal column lesion. J Gene Med 2006; 8:901-9. [PMID: 16718733 DOI: 10.1002/jgm.919] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND In previous studies, we showed that the immobilisation of DNAs encoding basic fibroblast growth factor, neurotrophin-3 and brain-derived neurotrophic factor in a gene-activated matrix (GAM) promotes sustained survival of axotomised retinal ganglion cells after optic nerve injury. Here, we evaluated if the immobilisation of DNAs in a GAM could be an effective approach to deliver genes to axotomised dorsal root ganglion (DRG) neurones after spinal cord injury and if the matrix component of the GAM would modulate the deposition of a dense scar at the injury site. METHODS We evaluated the expression of the thymidine kinase (TK) reporter gene in brain cortex and DRG after a bilateral T8 dorsal column (DC) lesion using PCR, RT-PCR and in situ hybridisation analyses. Collagen-based GAMs were implanted at the lesion site and the cellular response to the GAM was assessed using cell-specific markers. RESULTS At 1 week post-injury, PCR analyses confirmed that DNATK was retrogradely transported from the DC lesion where the GAM was implanted to the brain cortex and to caudal DRG neurones, and RT-PCR analyses showed expression of mRNATK. At 7 weeks post-injury, DNATK was still be detected in the GAM and DRG. In situ hybridisation localised DNATK and mRNATK within fibroblasts, glia, endothelial and inflammatory cells invading the GAM and in DRG neurones. Interestingly, the presence of a GAM also reduced secondary cavitation and scar deposition at the lesion site. CONCLUSIONS These results establish that GAMs act as bridging scaffolds in DC lesions limiting cavitation and scarring and delivering genes both locally to injury-reactive cells and distally to the cerebral cortex and to DRG neuronal somata through retrograde axonal transport.
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Affiliation(s)
- Ana Maria Gonzalez
- Molecular Neuroscience Group, Division of Medical Sciences, University of Birmingham, Birmingham B15 2TT, UK.
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22
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Logan A, Ahmed Z, Baird A, Gonzalez AM, Berry M. Neurotrophic factor synergy is required for neuronal survival and disinhibited axon regeneration after CNS injury. ACTA ACUST UNITED AC 2005; 129:490-502. [PMID: 16339795 DOI: 10.1093/brain/awh706] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The therapeutic effects of individual neurotrophic factors (NTF) have proved disappointing in clinical trials for neuronal repair and axon regeneration. Here, we demonstrate NTF synergistic neuronal responses after a combination of basic fibroblast growth factor, neurotrophin-3 and brain derived growth factor delivered to the somata of retinal ganglion cells promoted greater survival and axon growth than did the sum of the effects of each NTF alone. Triple and not single NTF treatments potentiated regulated intramembraneous proteolysis of p75(NTR), and ectodomain shedding of Nogo receptor, correlated with a 30% decrease in activation of Rho-A, a key signalling molecule in the axon growth inhibitory cascade. Thus, combinatorial NTF administration synergistically enhanced neuronal survival, disinhibited axon growth and promoted axon regeneration through the hostile CNS environment without the intervention of scar tissue at the lesion site.
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Affiliation(s)
- Ann Logan
- Molecular Neuroscience Group, Division of Medical Sciences, University of Birmingham, Birmingham, UK.
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23
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Lorber B, Hendriks WJAJ, Van der Zee CEEM, Berry M, Logan A. Effects of LAR and PTP-BL phosphatase deficiency on adult mouse retinal cells activated by lens injury. Eur J Neurosci 2005; 21:2375-83. [PMID: 15932596 DOI: 10.1111/j.1460-9568.2005.04065.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Using intact and lens-lesioned wildtype, leucocyte common antigen-related phosphatase deficient (LARDeltaP) and protein tyrosine phosphatase (PTP)-BAS-like phosphatase deficient (PTP-BLDeltaP) mice, we have evaluated the role of LAR and PTP-BL in retinal ganglion cell survival and neuritogenesis, and survival of activated retinal glia in vitro. There were no differences in in vitro retinal ganglion cell neuritogenesis and survival, as well as in activated retinal glia survival between intact wildtype and intact LARDeltaP or PTP-BLDeltaP mutant mice. In wildtype, LARDeltaP, and PTP-BLDeltaP retinal cultures, pre-conditioning by lens injury significantly increased retinal ganglion cell neuritogenesis and activated retinal glia numbers. However, in retinal cultures from lens-lesioned LARDeltaP and PTP-BLDeltaP mice, significantly smaller percentages of retinal ganglion cells grew neurites compared to lens-lesioned wildtype cultures. Significantly increased numbers of retinal ganglion cells survived in retinal cultures from lens-lesioned LARDeltaP mice compared to lens-lesioned wildtypes. PTP-BL phosphatase deficiency did not affect retinal ganglion cell survival in retinal cultures from lens-lesioned mice, though activated retinal glia numbers were significantly reduced in cultures from lens-lesioned PTP-BLDeltaP mice compared to lens-lesioned wildtypes. In summary, a functional phenotype was found in LARDeltaP and PTP-BLDeltaP mice, that was only obvious in lens lesion-stimulated retinal cultures. These observations suggest that LAR enhances retinal ganglion cell neurite initiation whilst suppressing retinal ganglion cell survival, and that PTP-BL facilitates both retinal ganglion cell neurite initiation and survival of activated retinal glia.
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Affiliation(s)
- Barbara Lorber
- Molecular Neuroscience Group, Department of Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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24
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Lorber B, Berry M, Logan A. Lens injury stimulates adult mouse retinal ganglion cell axon regeneration via both macrophage- and lens-derived factors. Eur J Neurosci 2005; 21:2029-34. [PMID: 15869497 DOI: 10.1111/j.1460-9568.2005.04034.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In the present study the effects of lens injury on retinal ganglion cell axon/neurite re-growth were investigated in adult mice. In vivo, lens injury promoted successful regeneration of retinal ganglion cell axons past the optic nerve lesion site, concomitant with the invasion of macrophages into the eye and the presence of activated retinal astrocytes/Muller cells. In vitro, retinal ganglion cells from lens-lesioned mice grew significantly longer neurites than those from intact mice, which correlated with the presence of enhanced numbers of activated retinal astrocytes/Muller cells. Co-culture of retinal ganglion cells from intact mice with macrophage-rich lesioned lens/vitreous body led to increased neurite lengths compared with co-culture with macrophage-free intact lens/vitreous body, pointing to a neurotrophic effect of macrophages. Furthermore, retinal ganglion cells from mice that had no lens injury but had received intravitreal Zymosan injections to stimulate macrophage invasion into the eye grew significantly longer neurites compared with controls, as did retinal ganglion cells from intact mice co-cultured with macrophage-rich vitreous body from Zymosan-treated mice. The intact lens, but not the intact vitreous body, exerted a neurotrophic effect on retinal ganglion cell neurite outgrowth, suggesting that lens-derived neurotrophic factor(s) conspire with those derived from macrophages in lens injury-stimulated axon regeneration. Together, these results show that lens injury promotes retinal ganglion cell axon regeneration/neurite outgrowth in adult mice, an observation with important implications for axon regeneration studies in transgenic mouse models.
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Affiliation(s)
- Barbara Lorber
- Molecular Neuroscience Group, Department of Medicine, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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