1
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Gupta R, Dittmeier M, Wohlleben G, Nickl V, Bischler T, Luzak V, Wegat V, Doll D, Sodmann A, Bady E, Langlhofer G, Wachter B, Havlicek S, Gupta J, Horn E, Lüningschrör P, Villmann C, Polat B, Wischhusen J, Monoranu CM, Kuper J, Blum R. Atypical cellular responses mediated by intracellular constitutive active TrkB (NTRK2) kinase domains and a solely intracellular NTRK2-fusion oncogene. Cancer Gene Ther 2024; 31:1357-1379. [PMID: 39039193 PMCID: PMC11405271 DOI: 10.1038/s41417-024-00809-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 06/25/2024] [Accepted: 07/11/2024] [Indexed: 07/24/2024]
Abstract
Trk (NTRK) receptor and NTRK gene fusions are oncogenic drivers of a wide variety of tumors. Although Trk receptors are typically activated at the cell surface, signaling of constitutive active Trk and diverse intracellular NTRK fusion oncogenes is barely investigated. Here, we show that a high intracellular abundance is sufficient for neurotrophin-independent, constitutive activation of TrkB kinase domains. In HEK293 cells, constitutive active TrkB kinase and an intracellular NTRK2-fusion oncogene (SQSTM1-NTRK2) reduced actin filopodia dynamics, phosphorylated FAK, and altered the cell morphology. Atypical cellular responses could be mimicked with the intracellular kinase domain, which did not activate the Trk-associated MAPK/ERK pathway. In glioblastoma-like U87MG cells, expression of TrkB or SQSTM1-NTRK2 reduced cell motility and caused drastic changes in the transcriptome. Clinically approved Trk inhibitors or mutating Y705 in the kinase domain, blocked the cellular effects and transcriptome changes. Atypical signaling was also seen for TrkA and TrkC. Moreover, hallmarks of atypical pTrk kinase were found in biopsies of Nestin-positive glioblastoma. Therefore, we suggest Western blot-like immunoassay screening of NTRK-related (brain) tumor biopsies to identify patients with atypical panTrk or phosphoTrk signals. Such patients could be candidates for treatment with NTRK inhibitors such as Larotrectinhib or Entrectinhib.
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Affiliation(s)
- Rohini Gupta
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Melanie Dittmeier
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Gisela Wohlleben
- Department of Radiation Oncology, University of Würzburg, Würzburg, Germany
| | - Vera Nickl
- Department of Neurosurgery, Section Experimental Neurosurgery, University Hospital Würzburg, Würzburg, Germany
| | - Thorsten Bischler
- Core Unit Systems Medicine, University of Würzburg, Würzburg, Germany
| | - Vanessa Luzak
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
- Ludwig-Maximilians-Universität München, Biomedizinisches Zentrum, Planegg, Germany
| | - Vanessa Wegat
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
- Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB, Bio- Elektro- und Chemokatalyse BioCat, Straubing, Germany
| | - Dennis Doll
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Annemarie Sodmann
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Elena Bady
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
- Institute of Pathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Georg Langlhofer
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Britta Wachter
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Steven Havlicek
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
- Neurona Therapeutics, 170 Harbor Way, South San Francisco, CA, USA
| | - Jahnve Gupta
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Evi Horn
- Department of Obstetrics and Gynecology, University Hospital Würzburg, Würzburg, Germany
| | - Patrick Lüningschrör
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Carmen Villmann
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Bülent Polat
- Department of Radiation Oncology, University of Würzburg, Würzburg, Germany
| | - Jörg Wischhusen
- Department of Obstetrics and Gynecology, University Hospital Würzburg, Würzburg, Germany
| | - Camelia M Monoranu
- Department of Neuropathology, Institute of Pathology, University of Würzburg, Würzburg, Germany
| | - Jochen Kuper
- Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Würzburg, Würzburg, Germany
| | - Robert Blum
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany.
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany.
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2
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Artim SC, Kiyatkin A, Lemmon MA. Comparison of tyrosine kinase domain properties for the neurotrophin receptors TrkA and TrkB. Biochem J 2020; 477:4053-4070. [PMID: 33043964 PMCID: PMC7606831 DOI: 10.1042/bcj20200695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/09/2020] [Accepted: 10/12/2020] [Indexed: 11/17/2022]
Abstract
The tropomyosin-related kinase (Trk) family consists of three receptor tyrosine kinases (RTKs) called TrkA, TrkB, and TrkC. These RTKs are regulated by the neurotrophins, a class of secreted growth factors responsible for the development and function of neurons. The Trks share a high degree of homology and utilize overlapping signaling pathways, yet their signaling is associated with starkly different outcomes in certain cancers. For example, in neuroblastoma, TrkA expression and signaling correlates with a favorable prognosis, whereas TrkB is associated with poor prognoses. To begin to understand how activation of the different Trks can lead to such distinct cellular outcomes, we investigated differences in kinase activity and duration of autophosphorylation for the TrkA and TrkB tyrosine kinase domains (TKDs). We find that the TrkA TKD has a catalytic efficiency that is ∼2-fold higher than that of TrkB, and becomes autophosphorylated in vitro more rapidly than the TrkB TKD. Studies with mutated TKD variants suggest that a crystallographic dimer seen in many TrkA (but not TrkB) TKD crystal structures, which involves the kinase-insert domain, may contribute to this enhanced TrkA autophosphorylation. Consistent with previous studies showing that cellular context determines whether TrkB signaling is sustained (promoting differentiation) or transient (promoting proliferation), we also find that TrkB signaling can be made more transient in PC12 cells by suppressing levels of p75NTR. Our findings shed new light on potential differences between TrkA and TrkB signaling, and suggest that subtle differences in signaling dynamics can lead to substantial shifts in the cellular outcome.
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Affiliation(s)
- Stephen C. Artim
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
- Present address: Merck Research Laboratories, Merck, South San Francisco, CA 94080, USA
| | - Anatoly Kiyatkin
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
- Department of Pharmacology and Cancer Biology Institute, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Mark A. Lemmon
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
- Department of Pharmacology and Cancer Biology Institute, Yale University School of Medicine, New Haven, CT, 06520, USA
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3
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Abstract
Autophosphorylation of kinases influences their conformational state and can also regulate enzymatic activity. Recently, this has become an area of interest for drug discovery. Using Alk2 as an example, we present two protocols - one based on phosphate-binding Alphascreen beads, the other on coupled luminescence measurements of ADP formation - that can be used to screen for inhibitors of autophosphorylation.
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Affiliation(s)
- Bianca Heedmann
- Center for Proteomic Chemistry, Novartis Institute for Biomedical Research Basel, Novartis Pharma AG, Postfach, CH-4002, Basel, Switzerland
| | - Martin Klumpp
- Center for Proteomic Chemistry, Novartis Institute for Biomedical Research Basel, Novartis Pharma AG, Postfach, CH-4002, Basel, Switzerland.
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4
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Sasi M, Vignoli B, Canossa M, Blum R. Neurobiology of local and intercellular BDNF signaling. Pflugers Arch 2017; 469:593-610. [PMID: 28280960 PMCID: PMC5438432 DOI: 10.1007/s00424-017-1964-4] [Citation(s) in RCA: 205] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Revised: 02/27/2017] [Accepted: 02/28/2017] [Indexed: 01/07/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of secreted proteins. Signaling cascades induced by BDNF and its receptor, the receptor tyrosine kinase TrkB, link neuronal growth and differentiation with synaptic plasticity. For this reason, interference with BDNF signaling has emerged as a promising strategy for potential treatments in psychiatric and neurological disorders. In many brain circuits, synaptically released BDNF is essential for structural and functional long-term potentiation, two prototypical cellular models of learning and memory formation. Recent studies have revealed an unexpected complexity in the synaptic communication of mature BDNF and its precursor proBDNF, not only between local pre- and postsynaptic neuronal targets but also with participation of glial cells. Here, we consider recent findings on local actions of the BDNF family of ligands at the synapse and discuss converging lines of evidence which emerge from per se conflicting results.
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Affiliation(s)
- Manju Sasi
- Institute of Clinical Neurobiology, University Hospital, University of Würzburg, 97078, Würzburg, Germany
| | - Beatrice Vignoli
- Centre for Integrative Biology (CIBIO), University of Trento, 38123, Povo, TN, Italy
| | - Marco Canossa
- Centre for Integrative Biology (CIBIO), University of Trento, 38123, Povo, TN, Italy.,European Brain Research Institute (EBRI) "Rita Levi-Montalcini", 00143, Rome, Italy
| | - Robert Blum
- Institute of Clinical Neurobiology, University Hospital, University of Würzburg, 97078, Würzburg, Germany.
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5
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Kleene R, Cassens C, Bähring R, Theis T, Xiao MF, Dityatev A, Schafer-Nielsen C, Döring F, Wischmeyer E, Schachner M. Functional consequences of the interactions among the neural cell adhesion molecule NCAM, the receptor tyrosine kinase TrkB, and the inwardly rectifying K+ channel KIR3.3. J Biol Chem 2010; 285:28968-79. [PMID: 20610389 DOI: 10.1074/jbc.m110.114876] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cell adhesion molecules and neurotrophin receptors are crucial for the development and the function of the nervous system. Among downstream effectors of neurotrophin receptors and recognition molecules are ion channels. Here, we provide evidence that G protein-coupled inwardly rectifying K(+) channel Kir3.3 directly binds to the neural cell adhesion molecule (NCAM) and neurotrophin receptor TrkB. We identified the binding sites for NCAM and TrkB at the C-terminal intracellular domain of Kir3.3. The interaction between NCAM, TrkB, and Kir3.3 was supported by immunocytochemical co-localization of Kir3.3, NCAM, and/or TrkB at the surface of hippocampal neurons. Co-expression of TrkB and Kir3.1/3.3 in Xenopus oocytes increased the K(+) currents evoked by Kir3.1/3.3 channels. This current enhancement was reduced by the concomitant co-expression with NCAM. Both surface fluorescence measurements of microinjected oocytes and cell surface biotinylation of transfected CHO cells indicated that the cell membrane localization of Kir3.3 is regulated by TrkB and NCAM. Furthermore, the level of Kir3.3, but not of Kir3.2, at the plasma membranes was reduced in TrkB-deficient mice, supporting the notion that TrkB regulates the cell surface expression of Kir3.3. The premature expression of developmentally late appearing Kir3.1/3.3 in hippocampal neurons led to a reduction of NCAM-induced neurite outgrowth. Our observations indicate a decisive role for the neuronal K(+) channel in regulating NCAM-dependent neurite outgrowth and attribute a physiologically meaningful role to the functional interplay of Kir3.3, NCAM, and TrkB in ontogeny.
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Affiliation(s)
- Ralf Kleene
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 85, 20246 Hamburg, Germany
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6
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Cassens C, Kleene R, Xiao MF, Friedrich C, Dityateva G, Schafer-Nielsen C, Schachner M. Binding of the receptor tyrosine kinase TrkB to the neural cell adhesion molecule (NCAM) regulates phosphorylation of NCAM and NCAM-dependent neurite outgrowth. J Biol Chem 2010; 285:28959-67. [PMID: 20605779 DOI: 10.1074/jbc.m110.114835] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Recognition molecules and neurotrophins play important roles during development and maintenance of nervous system functions. In this study, we provide evidence that the neural cell adhesion molecule (NCAM) and the neurotrophin receptor TrkB directly interact via sequences in their intracellular domains. Stimulation of TrkB by brain-derived neurotrophic factor leads to tyrosine phosphorylation of NCAM at position 734. Mutation of this tyrosine to phenylalanine completely abolishes tyrosine phosphorylation of NCAM by TrkB. Moreover, the knockdown of TrkB in hippocampal neurons leads to a reduction of NCAM-induced neurite outgrowth. Transfection of NCAM-deficient hippocampal neurons with mutated NCAM carrying an exchange of tyrosine by phenylalanine at position 734 leads to promotion of NCAM-induced neurite outgrowth in comparison with that observed after transfection with wild-type NCAM, whereas a reduction of neurite outgrowth was observed after transfection with mutated NCAM, which carries an exchange of tyrosine by glutamate that mimics the phosphorylated tyrosine. Our observations indicate a functional relationship between TrkB and NCAM.
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Affiliation(s)
- Claas Cassens
- Zentrum für Molekulare Neurobiologie, Universität Hamburg, Martinistrasse 85, 20246 Hamburg, Germany
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7
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Sheth PR, Hays JL, Elferink LA, Watowich SJ. Biochemical basis for the functional switch that regulates hepatocyte growth factor receptor tyrosine kinase activation. Biochemistry 2008; 47:4028-38. [PMID: 18324780 DOI: 10.1021/bi701892f] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Ligand-induced dimerization of receptor tyrosine kinases (RTKs) modulates a system of linked biochemical reactions, sharply switching the RTK from a quiescent state to an active state that becomes phosphorylated and triggers intracellular signaling pathways. To improve our understanding of this molecular switch, we developed a quantitative model for hepatocyte growth factor receptor (c-MET) activation using parameters derived in large part from c-MET kinetic and thermodynamic experiments. Our model accurately produces the qualitative and quantitative dynamic features of c-MET phosphorylation observed in cells following ligand binding, including a rapid transient buildup of phosphorylated c-MET at high ligand concentrations. In addition, our model predicts a slow buildup of phosphorylated c-MET under conditions of reduced phosphatase activity and no extracellular agonist. Significantly, this predicted response is observed in cells treated with phosphatase inhibitors, further validating our model. Parameter sensitivity studies clearly show that synergistic oligomerization-dependent changes in c-MET kinetic, thermodynamic, and dephosphorylation properties result in the selective activation of the dimeric receptor, confirming that this model can be used to accurately evaluate the relative importance of linked biochemical reactions important for c-MET activation. Our model suggests that the functional differences observed between c-MET monomers and dimers may have incrementally evolved to optimize cell surface signaling responses.
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Affiliation(s)
- Payal R Sheth
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555-0645, USA
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8
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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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9
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Seki M, Tanaka T, Nawa H, Usui T, Fukuchi T, Ikeda K, Abe H, Takei N. Involvement of brain-derived neurotrophic factor in early retinal neuropathy of streptozotocin-induced diabetes in rats: therapeutic potential of brain-derived neurotrophic factor for dopaminergic amacrine cells. Diabetes 2004; 53:2412-9. [PMID: 15331553 DOI: 10.2337/diabetes.53.9.2412] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Although neurotrophins have been assessed as candidate therapeutic agents for neural complications of diabetes, their involvement in diabetic retinopathy has not been fully characterized. We found that the protein and mRNA levels of brain-derived neurotrophic factor (BDNF) in streptozotocin-induced diabetic rat retinas were reduced to 49% (P < 0.005) and 74% (P < 0.05), respectively, of those of normal control animals. In addition, dopaminergic amacrine cells appeared to be degenerating in the diabetic rat retinas, as revealed by tyrosine hydroxylase (TH) immunoreactivity. Overall TH protein levels in the retina were decreased to one-half that of controls (P < 0.01), reflecting reductions in the density of dopaminergic amacrine cells and the intensity of TH immunoreactivity within them. To confirm the neuropathological implications of BDNF reduction, we administered BDNF protein into the vitreous cavities of diabetic rats. Intraocular administration of BDNF rescued dopaminergic amacrine cells from neurodegeneration and counteracted the downregulation of TH expression, demonstrating its therapeutic potential. These findings suggest that the early retinal neuropathy of diabetes involves the reduced expression of BDNF and can be ameliorated by an exogenous supply of this neurotrophin.
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Affiliation(s)
- Masaaki Seki
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University, 1-757 Asahimachi, Niigata, Niigata 951-8585, Japan
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10
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Nakamura T, Komiya M, Gotoh N, Koizumi S, Shibuya M, Mori N. Discrimination between phosphotyrosine-mediated signaling properties of conventional and neuronal Shc adapter molecules. Oncogene 2002; 21:22-31. [PMID: 11791173 DOI: 10.1038/sj.onc.1205019] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2001] [Revised: 09/24/2001] [Accepted: 10/01/2001] [Indexed: 11/08/2022]
Abstract
The phosphotyrosine (pTyr) adapter Shc/ShcA is a major connector in various tyrosine kinase signalings following a variety of stimulation such as growth factor/neurotrophin, as well as in those following calcium influx and integrin activation. As in other tissues, Shc has been implicated in neuronal signalings; however, recent evidence suggests that N-Shc/ShcC and Sck/ShcB would take over most of the roles of Shc in mature central neurons, and switching phenomena between Shc and N-Shc expression were observed in several neuronal paradigms. Little is, however, known as to the signal-output differences between Shc and N-Shc. Here we determined the efficacy of Shc and N-Shc toward Erk activation in NGF-treated PC12 cells, and found that N-Shc transduced Grb2/Sos/Ras-dependent Erk activation less efficiently than Shc. This was mainly because N-Shc has only one high-affinity Grb2-binding site, whereas Shc has two such sites. Phosphopeptide mapping revealed that N-Shc has novel tyrosine-phosphorylation sites at Y259/Y260 and Y286; in vivo-phosphorylation of these tyrosines was demonstrated by site-specific anti-pTyr antibodies. Phosphorylated Y286 bound to several proteins, of which one was Crk. The pY221/pY222 site, corresponding to one of the Grb2-binding sites of Shc, also preferentially bound to Crk. The phosphorylation-dependent interaction between N-Shc and Crk was demonstrated in vitro and in vivo. These results indicate that N-Shc has specific features of signal-output, and further suggest that the switching between Shc and N-Shc during neural development and regeneration would lead to differentiation of downstream signalings.
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Affiliation(s)
- Takeshi Nakamura
- Department of Molecular Genetics, National Institute for Longevity Sciences, Oobu, Aichi 474-8522, Japan
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11
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McKay SE, Hislop J, Scott D, Bulloch AG, Kaczmarek LK, Carew TJ, Sossin WS. Aplysia ror forms clusters on the surface of identified neuroendocrine cells. Mol Cell Neurosci 2001; 17:821-41. [PMID: 11358481 DOI: 10.1006/mcne.2001.0977] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ror receptors are a highly conserved family of receptor tyrosine kinases genetically implicated in the establishment of cellular polarity. We have cloned a ror receptor from the marine mollusk Aplysia californica. Aplysia ror (Apror) is expressed in most developing neurons and some adult neuronal populations, including the neuroendocrine bag-cell neurons. The Apror protein is present in peripheral neuronal processes and ganglionic neuropil, implicating the kinase in the regulation of growth and/or synaptic events. In cultured bag-cell neurons, the majority of the protein is stored in intracellular organelles, whereas only a small fraction is expressed on the surface. When expressed on the cell surface, the protein is clustered on neurites, suggesting that Apror is involved in the organization of functional domains within neurons. Apror immunoreactivity partially colocalizes with the P-type calcium channel BC-alpha1A at bag-cell neuron varicosities, suggesting a role for Apror in organizing neuropeptide release sites.
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MESH Headings
- Age Factors
- Amino Acid Sequence/physiology
- Animals
- Antibody Specificity
- Aplysia/chemistry
- Aplysia/cytology
- Aplysia/metabolism
- Base Sequence/physiology
- Caenorhabditis elegans Proteins
- Cell Compartmentation/physiology
- Cells, Cultured/cytology
- Cells, Cultured/metabolism
- Cloning, Molecular
- Ganglia, Invertebrate/cytology
- Ganglia, Invertebrate/growth & development
- Ganglia, Invertebrate/metabolism
- Immunohistochemistry
- Molecular Sequence Data
- Neurons/cytology
- Neurons/metabolism
- Neurosecretory Systems/cytology
- Neurosecretory Systems/growth & development
- Neurosecretory Systems/metabolism
- RNA, Messenger/metabolism
- Receptor Protein-Tyrosine Kinases/chemistry
- Receptor Protein-Tyrosine Kinases/genetics
- Receptor Protein-Tyrosine Kinases/isolation & purification
- Receptor Tyrosine Kinase-like Orphan Receptors
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/isolation & purification
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Affiliation(s)
- S E McKay
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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