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In vivo functions of p75 NTR: challenges and opportunities for an emerging therapeutic target. Trends Pharmacol Sci 2021; 42:772-788. [PMID: 34334250 DOI: 10.1016/j.tips.2021.06.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 05/31/2021] [Accepted: 06/28/2021] [Indexed: 12/24/2022]
Abstract
The p75 neurotrophin receptor (p75NTR) functions at the molecular nexus of cell death, survival, and differentiation. In addition to its contribution to neurodegenerative diseases and nervous system injuries, recent studies have revealed unanticipated roles of p75NTR in liver repair, fibrinolysis, lung fibrosis, muscle regeneration, and metabolism. Linking these various p75NTR functions more precisely to specific mechanisms marks p75NTR as an emerging candidate for therapeutic intervention in a wide range of disorders. Indeed, small molecule inhibitors of p75NTR binding to neurotrophins have shown efficacy in models of Alzheimer's disease (AD) and neurodegeneration. Here, we outline recent advances in understanding p75NTR pleiotropic functions in vivo, and propose an integrated view of p75NTR and its challenges and opportunities as a pharmacological target.
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Ozalp O, Cark O, Azbazdar Y, Haykir B, Cucun G, Kucukaylak I, Alkan-Yesilyurt G, Sezgin E, Ozhan G. Nradd Acts as a Negative Feedback Regulator of Wnt/β-Catenin Signaling and Promotes Apoptosis. Biomolecules 2021; 11:100. [PMID: 33466728 PMCID: PMC7828832 DOI: 10.3390/biom11010100] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/05/2021] [Accepted: 01/11/2021] [Indexed: 12/16/2022] Open
Abstract
Wnt/β-catenin signaling controls many biological processes for the generation and sustainability of proper tissue size, organization and function during development and homeostasis. Consequently, mutations in the Wnt pathway components and modulators cause diseases, including genetic disorders and cancers. Targeted treatment of pathway-associated diseases entails detailed understanding of the regulatory mechanisms that fine-tune Wnt signaling. Here, we identify the neurotrophin receptor-associated death domain (Nradd), a homolog of p75 neurotrophin receptor (p75NTR), as a negative regulator of Wnt/β-catenin signaling in zebrafish embryos and in mammalian cells. Nradd significantly suppresses Wnt8-mediated patterning of the mesoderm and neuroectoderm during zebrafish gastrulation. Nradd is localized at the plasma membrane, physically interacts with the Wnt receptor complex and enhances apoptosis in cooperation with Wnt/β-catenin signaling. Our functional analyses indicate that the N-glycosylated N-terminus and the death domain-containing C-terminus regions are necessary for both the inhibition of Wnt signaling and apoptosis. Finally, Nradd can induce apoptosis in mammalian cells. Thus, Nradd regulates cell death as a modifier of Wnt/β-catenin signaling during development.
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Affiliation(s)
- Ozgun Ozalp
- Izmir Biomedicine and Genome Center (IBG), Dokuz Eylul University Health Campus, Inciralti-Balcova, 35340 Izmir, Turkey; (O.O.); (O.C.); (Y.A.); (B.H.); (G.C.); (I.K.); (G.A.-Y.)
- Izmir International Biomedicine and Genome Institute (IBG-Izmir), Dokuz Eylul University, Inciralti-Balcova, 35340 Izmir, Turkey
| | - Ozge Cark
- Izmir Biomedicine and Genome Center (IBG), Dokuz Eylul University Health Campus, Inciralti-Balcova, 35340 Izmir, Turkey; (O.O.); (O.C.); (Y.A.); (B.H.); (G.C.); (I.K.); (G.A.-Y.)
- Izmir International Biomedicine and Genome Institute (IBG-Izmir), Dokuz Eylul University, Inciralti-Balcova, 35340 Izmir, Turkey
| | - Yagmur Azbazdar
- Izmir Biomedicine and Genome Center (IBG), Dokuz Eylul University Health Campus, Inciralti-Balcova, 35340 Izmir, Turkey; (O.O.); (O.C.); (Y.A.); (B.H.); (G.C.); (I.K.); (G.A.-Y.)
- Izmir International Biomedicine and Genome Institute (IBG-Izmir), Dokuz Eylul University, Inciralti-Balcova, 35340 Izmir, Turkey
| | - Betul Haykir
- Izmir Biomedicine and Genome Center (IBG), Dokuz Eylul University Health Campus, Inciralti-Balcova, 35340 Izmir, Turkey; (O.O.); (O.C.); (Y.A.); (B.H.); (G.C.); (I.K.); (G.A.-Y.)
- Institute of Physiology, Switzerland and National Center of Competence in Research NCCR Kidney, University of Zurich, CH-8057 Zurich, Switzerland
| | - Gokhan Cucun
- Izmir Biomedicine and Genome Center (IBG), Dokuz Eylul University Health Campus, Inciralti-Balcova, 35340 Izmir, Turkey; (O.O.); (O.C.); (Y.A.); (B.H.); (G.C.); (I.K.); (G.A.-Y.)
- Izmir International Biomedicine and Genome Institute (IBG-Izmir), Dokuz Eylul University, Inciralti-Balcova, 35340 Izmir, Turkey
| | - Ismail Kucukaylak
- Izmir Biomedicine and Genome Center (IBG), Dokuz Eylul University Health Campus, Inciralti-Balcova, 35340 Izmir, Turkey; (O.O.); (O.C.); (Y.A.); (B.H.); (G.C.); (I.K.); (G.A.-Y.)
- Institute of Zoology-Developmental Biology, University of Cologne, 50674 Cologne, Germany
| | - Gozde Alkan-Yesilyurt
- Izmir Biomedicine and Genome Center (IBG), Dokuz Eylul University Health Campus, Inciralti-Balcova, 35340 Izmir, Turkey; (O.O.); (O.C.); (Y.A.); (B.H.); (G.C.); (I.K.); (G.A.-Y.)
| | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women’s and Children’s Health, Karolinska Institutet, 17177 Stockholm, Sweden;
- MRC Weatherall Institute of Molecular Medicine, MRC Human Immunology Unit, University of Oxford, Oxford OX39DS, UK
| | - Gunes Ozhan
- Izmir Biomedicine and Genome Center (IBG), Dokuz Eylul University Health Campus, Inciralti-Balcova, 35340 Izmir, Turkey; (O.O.); (O.C.); (Y.A.); (B.H.); (G.C.); (I.K.); (G.A.-Y.)
- Izmir International Biomedicine and Genome Institute (IBG-Izmir), Dokuz Eylul University, Inciralti-Balcova, 35340 Izmir, Turkey
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3
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Nadezhdin KD, Goncharuk SA, Arseniev AS, Mineev KS. NMR structure of a full-length single-pass membrane protein NRADD. Proteins 2019; 87:786-790. [PMID: 31033000 DOI: 10.1002/prot.25703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 04/05/2019] [Accepted: 04/23/2019] [Indexed: 01/22/2023]
Abstract
Structural study of any single-pass membrane protein is both an important and challenging task. In this report, we present the structure of a neurotrophin receptor-alike death-domain protein. The structure and dynamics of the protein was investigated by conventional nuclear magnetic resonance techniques in the solution of phospholipid bicelles. The receptor contains two folded regions-α-helical transmembrane domain and globular C-terminal death domain with more than 50% of the rest of backbone being disordered. This is the first structure of a full-length single-pass membrane receptor-alike protein solved by the single method.
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Affiliation(s)
- Kirill D Nadezhdin
- Laboratory of biomolecular NMR spectroscopy, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia.,Department of biological and medical physics, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Sergey A Goncharuk
- Laboratory of biomolecular NMR spectroscopy, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia
| | - Aleksander S Arseniev
- Laboratory of biomolecular NMR spectroscopy, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia.,Department of biological and medical physics, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Konstantin S Mineev
- Laboratory of biomolecular NMR spectroscopy, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia.,Department of biological and medical physics, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
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Yuan W, Ibáñez CF, Lin Z. Death domain of p75 neurotrophin receptor: a structural perspective on an intracellular signalling hub. Biol Rev Camb Philos Soc 2019; 94:1282-1293. [PMID: 30762293 DOI: 10.1111/brv.12502] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 01/23/2019] [Accepted: 01/24/2019] [Indexed: 12/19/2022]
Abstract
The death domain (DD) is a globular protein motif with a signature feature of an all-helical Greek-key motif. It is a primary mediator of a variety of biological activities, including apoptosis, cell survival and cytoskeletal changes, which are related to many neurodegenerative diseases, neurotrauma, and cancers. DDs exist in a wide range of signalling proteins including p75 neurotrophin receptor (p75NTR ), a member of the tumour necrosis factor receptor superfamily. The specific signalling mediated by p75NTR in a given cell depends on the type of ligand engaging the extracellular domain and the recruitment of cytosolic interactors to the intracellular domain, especially the DD, of the receptor. In solution, the p75NTR -DDs mainly form a symmetric non-covalent homodimer. In response to extracellular signals, conformational changes in the p75NTR extracellular domain (ECD) propagate to the p75NTR -DD through the disulfide-bonded transmembrane domain (TMD) and destabilize the p75NTR -DD homodimer, leading to protomer separation and exposure of binding sites on the DD surface. In this review, we focus on recent advances in the study of the structural mechanism of p75NTR -DD signalling through recruitment of diverse intracellular interactors for the regulation and control of diverse functional outputs.
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Affiliation(s)
- Wensu Yuan
- School of Life Sciences, Tianjin University, Tianjin, 300072, People's Republic of China
| | - Carlos F Ibáñez
- Department of Physiology, National University of Singapore, 117456, Singapore.,Life Sciences Institute, National University of Singapore, 117456, Singapore.,Department of Cell & Molecular Biology, Karolinska Institute, 17165, Stockholm, Sweden
| | - Zhi Lin
- School of Life Sciences, Tianjin University, Tianjin, 300072, People's Republic of China.,Department of Physiology, National University of Singapore, 117456, Singapore.,Life Sciences Institute, National University of Singapore, 117456, Singapore
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Unsain N, Dorval G, Sheen JH, Barker PA. Generation and characterization of mice bearing null alleles of nradd/Nrh2. Genesis 2016; 54:605-612. [PMID: 27775873 DOI: 10.1002/dvg.22989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 10/10/2016] [Accepted: 10/20/2016] [Indexed: 11/11/2022]
Abstract
The Neurotrophin receptor associated death domain gene (Nradd/Nrh2/Plaidd) is a type I transmembrane protein with a unique and short N-terminal extracellular domain and a transmembrane and intracellular domain that bears high similarity to the p75 neurotrophin receptor (p75NTR/Ngfr). Initial studies suggested that NRADD regulates neurotrophin signaling but very little is known about its physiological roles. We have generated and characterized NRADD conditional and germ-line null mouse lines. These mice are viable and fertile and dońt show evident abnormalities. However, NRADD deletion results in an increase in the proportion of dorsal root ganglion neurons expressing p75NTR. The NRADD conditional and complete knockout mouse lines generated are new and useful tools to study the physiological roles of NRADD. Birth Defects Research (Part A) 106:605-612, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Nicolas Unsain
- Laboratorio de Neurobiología, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Friuli 2434, Córdoba, 5016, Argentina
| | - Genevieve Dorval
- Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, QCH3A 2B4, Canada
| | - Jae Hyung Sheen
- Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, QCH3A 2B4, Canada
| | - Philip A Barker
- Vice Principal Research University of British Columbia, Okanagan Campus, 3247 University Way, Kelowna, British Columbia, V1V1V7, Canada
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Vilar M. Structural Characterization of the p75 Neurotrophin Receptor: A Stranger in the TNFR Superfamily. VITAMINS AND HORMONES 2016; 104:57-87. [PMID: 28215307 DOI: 10.1016/bs.vh.2016.10.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Although p75 neurotrophin receptor (p75NTR) was the founding member of the tumor necrosis factor (TNF) receptor superfamily (TNFRSF), it is an atypical TNFRSF protein. p75NTR like TNF-R1 and Fas-R contain an extracellular domain with four cysteine-rich domains (CRD) and a death domain (DD) in the intracellular region. While TNFRSF proteins are activated by trimeric TNFSF ligands, p75NTR forms dimers activated by dimeric neurotrophins that are structurally unrelated to TNFSF proteins. In addition, although p75NTR shares with other members the interaction with the TNF receptor-associated factors to activate the NF-κB and cell death pathways, p75NTR does not interact with the DD-containing proteins FADD, TRADD, or MyD88. By contrast, the DD of p75NTR is able to recruit several protein interactors via a full catalog of DD interactions not described before in the TNFRSF. p75-DD forms homotypic symmetrical DD-DD complexes with itself and with the related p45-DD; forms heterotypic DD-CARD interactions with the RIP2-CARD domain, and forms a new interaction between a DD and RhoGDI. All these features, in addition to its promiscuous interactions with several ligands and coreceptors, its processing by α- and γ-secretases, the dimeric nature of its transmembrane domain and its "special" juxtamembrane region, make p75NTR a truly stranger in the TNFR superfamily. In this chapter, I will summarize the known structural aspects of p75NTR and I will analyze from a structural point of view, the similitudes and differences between p75NTR and the other members of the TNFRSF.
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Affiliation(s)
- M Vilar
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of Valencia (IBV-CSIC), València, Spain.
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Vilar M, Sung TC, Chen Z, García-Carpio I, Fernandez EM, Xu J, Riek R, Lee KF. Heterodimerization of p45-p75 modulates p75 signaling: structural basis and mechanism of action. PLoS Biol 2014; 12:e1001918. [PMID: 25093680 PMCID: PMC4122344 DOI: 10.1371/journal.pbio.1001918] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 06/25/2014] [Indexed: 12/26/2022] Open
Abstract
The formation of a p45-p75 heterodimer overrides p75’s inhibition of nerve regeneration by stopping p75 homodimers from forming and creating a complex with the Nogo receptor. The p75 neurotrophin receptor, a member of the tumor necrosis factor receptor superfamily, is required as a co-receptor for the Nogo receptor (NgR) to mediate the activity of myelin-associated inhibitors such as Nogo, MAG, and OMgp. p45/NRH2/PLAIDD is a p75 homologue and contains a death domain (DD). Here we report that p45 markedly interferes with the function of p75 as a co-receptor for NgR. P45 forms heterodimers with p75 and thereby blocks RhoA activation and inhibition of neurite outgrowth induced by myelin-associated inhibitors. p45 binds p75 through both its transmembrane (TM) domain and DD. To understand the underlying mechanisms, we have determined the three-dimensional NMR solution structure of the intracellular domain of p45 and characterized its interaction with p75. We have identified the residues involved in such interaction by NMR and co-immunoprecipitation. The DD of p45 binds the DD of p75 by electrostatic interactions. In addition, previous reports suggested that Cys257 in the p75 TM domain is required for signaling. We found that the interaction of the cysteine 58 of p45 with the cysteine 257 of p75 within the TM domain is necessary for p45–p75 heterodimerization. These results suggest a mechanism involving both the TM domain and the DD of p45 to regulate p75-mediated signaling. Injuries to the brain and spinal cord often result in paralysis due to the fact that the injured nerves cannot regrow to reach their normal targets and carry out their functions. At the injury sites, there are proteins released from the damaged myelin that bind the Nogo receptor (NgR) on the nerve and inhibit its regeneration. The NgR needs to form a complex with the p75 neurotrophin receptor in order to mediate this inhibitory signal. Here we found that p45, a homologue of p75, can also bind to p75 and block its inhibitory activity when overexpressed. To perform its function, p75 needs to dimerize through both its transmembrane and intracellular domains, facilitating the recruitment of several proteins. Our structural and functional studies show that p45 binds specifically to conserved regions in the p75 transmembrane and the intracellular domain and that this blocks p75 dimerization along with its downstream signaling. Thus, this study demonstrates that altering the oligomerization of p75 is a good strategy to override p75's inhibitory effects on nerve regeneration, and it opens the door for the design of specific p75 inhibitors for therapeutic applications.
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Affiliation(s)
- Marçal Vilar
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
- Neurodegeneration Unit, Chronic Disease Program, Spanish Institute of Health Carlos III, Madrid, Spain
- * E-mail: (K.-F.L.); (R.R.); (M.V.)
| | - Tsung-Chang Sung
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
| | - Zhijiang Chen
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
| | - Irmina García-Carpio
- Neurodegeneration Unit, Chronic Disease Program, Spanish Institute of Health Carlos III, Madrid, Spain
| | - Eva M. Fernandez
- Neurodegeneration Unit, Chronic Disease Program, Spanish Institute of Health Carlos III, Madrid, Spain
| | - Jiqing Xu
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
| | - Roland Riek
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
- Laboratory for Physical Chemistry, ETH Zürich, Zürich, Switzerland
- * E-mail: (K.-F.L.); (R.R.); (M.V.)
| | - Kuo-Fen Lee
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
- * E-mail: (K.-F.L.); (R.R.); (M.V.)
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Chen RC, Chuang LY, Tseng WL, Tyan YC, Lu CY. Determination of phosphoserine/threonine by nano ultra-performance liquid chromatography-tandem mass spectrometry coupled with microscale labeling. Anal Biochem 2013; 443:187-96. [PMID: 23994561 DOI: 10.1016/j.ab.2013.08.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Revised: 08/17/2013] [Accepted: 08/21/2013] [Indexed: 11/18/2022]
Abstract
Protein phosphorylation is an important regulatory post-translational modification in many biochemical processes. The phosphopeptide analysis strategies developed in this study were all at microscale. After using a standard microwave oven to assist protein digestion, phosphoserine and phosphothreonine were tagged with chemical analogues, such as 2-mercaptoethanol and 3-mercapto-1-propanol, to enable simultaneously relative quantitation and identification. This method enabled the use of thio alcohols for direct labeling of phosphorylated sites (not labeled at the mercapto, amino, hydroxyl, or carboxyl groups) of phosphopeptides. Various digestion parameters (e.g., microwave power, reaction time, NH4HCO3 concentration) and derivatization efficiency parameters (e.g., reaction time, labeling tag concentration) were studied and optimized. In both control and experimental samples, microwave-assisted digestion coupled with relative quantitation using analogue tags enabled calculation of phosphopeptide ratios in the same sequence. A non-labeling method was also established for quantifying phosphopeptides in human plasma by using the abundant protein albumin as an internal control for normalizing relative quantities of phosphopeptides. Nano ultra-performance liquid chromatography (nanoUPLC) was combined with LTQ Orbitrap to enable simultaneous protein relative quantitation and identification. These strategies proved to be effective for quantifying phosphopeptides in biological samples.
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Affiliation(s)
- Rong-Chun Chen
- Department of Biochemistry, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
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Sung TC, Chen Z, Thuret S, Vilar M, Gage FH, Riek R, Lee KF. P45 forms a complex with FADD and promotes neuronal cell survival following spinal cord injury. PLoS One 2013; 8:e69286. [PMID: 23935974 PMCID: PMC3720591 DOI: 10.1371/journal.pone.0069286] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 06/06/2013] [Indexed: 12/02/2022] Open
Abstract
Fas-associated death domain (DD) adaptor (FADD), a member of the DD superfamily, contains both a DD and a death effector domain (DED) that are important in mediating FAS ligand-induced apoptotic signaling. P45 is a unique member of the DD superfamily in that it has a domain with sequence and structural characteristics of both DD and DED. We show that p45 forms a complex with FADD and diminishes Fas-FADD mediated death signaling. The DED of FADD is required for the complex formation with p45. Following spinal cord injury, transgenic mice over-expressing p45 exhibit increased neuronal survival, decreased retraction of corticospinal tract fibers and improved functional recovery. Understanding p45-mediated cellular and molecular mechanisms may provide insights into facilitating nerve regeneration in humans.
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Affiliation(s)
- Tsung-Chang Sung
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
| | - Zhijiang Chen
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
| | - Sandrine Thuret
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
- Centre for the Cellular Basis of Behaviour & Medical Research Council Centre for Neurodegeneration Research, Institute of Psychiatry, King’s College London, London, United Kingdom
| | - Marçal Vilar
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
- Neurodegeneration Unit, Instituto de Salud Carlos III, Madrid, Spain
| | - Fred H. Gage
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
| | - Roland Riek
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
- Laboratory for Physical Chemistry, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | - Kuo-Fen Lee
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California, United States of America
- * E-mail:
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10
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Mok SA, Lund K, Lapointe P, Campenot RB. A HaloTag® method for assessing the retrograde axonal transport of the p75 neurotrophin receptor and other proteins in compartmented cultures of rat sympathetic neurons. J Neurosci Methods 2013; 214:91-104. [PMID: 23348044 DOI: 10.1016/j.jneumeth.2013.01.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 10/19/2012] [Accepted: 01/08/2013] [Indexed: 11/30/2022]
Abstract
We have adapted HaloTag® (HT) technology for use in compartmented cultures of rat sympathetic neurons in order to provide a technique that can be broadly applied to studies of the retrograde transport of molecules that play roles in neurotrophin signaling. Transfected neurons expressing HT protein alone, HT protein fused to the p75 neurotrophin receptor (p75NTR) or HT protein fused to tubulin α-1B were maintained in compartmented cultures in which cell bodies and proximal axons of rat sympathetic neurons reside in proximal compartments and their distal axons extend into distal compartments. HT ligand containing a fluorescent tetramethylrhodamine (TMR) label was applied either in the distal compartments or the proximal compartments, and the transport of labeled proteins was assayed by gel fluorescence imaging and TMR immunoblot. HT protein expressed alone displayed little or no retrograde transport. HT protein fused to either the intracellular C-terminus or the extracellular N-terminus of p75NTR was retrogradely transported. The retrograde transport of p75NTR was augmented when the distal axons were provided with nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) or antibodies to BDNF. The anterograde transport of HT protein fused to the N-terminus of tubulin α-1B was also demonstrated. We conclude that retrograde transport of HT fusion proteins provides a powerful and novel approach in studies of axonal transport.
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Affiliation(s)
- Sue-Ann Mok
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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11
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Teng KK, Felice S, Kim T, Hempstead BL. Understanding proneurotrophin actions: Recent advances and challenges. Dev Neurobiol 2010; 70:350-9. [PMID: 20186707 DOI: 10.1002/dneu.20768] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neurotrophins are initially synthesized as larger precursors (proneurotrophins), which undergo proteolytic cleavage to yield mature forms. Although the functions of the mature neurotrophins have been well established during neural development and in the adult nervous system, roles for the proneurotrophins in developmental and injury-induced cell death, as well as in synaptic plasticity, have only recently been appreciated. Interestingly, both mature neurotrophins and proneurotrophins utilize dual-receptor complexes to mediate their actions. The mature neurotrophin coreceptors consist of the Trk receptor tyrosine kinases and p75(NTR), wherein Trk transduces survival and differentiative signaling, and p75(NTR) modulates the affinity and selectivity of Trk activation. On the other hand, proneurotrophins engage p75(NTR) and the structurally distinct coreceptor sortilin, to initiate p75(NTR)-dependent signal transduction cascade. Although the specificity of mature neurotrophins vs. proneurotrophins actions is due in part to the formation of distinct coreceptor complexes, a number of recent studies highlight how different p75(NTR)-mediated cellular actions are modulated. Here, we review emerging evidence for a novel transmembrane mechanism for ligand-specific p75(NTR) activation and several mechanisms by which p75(NTR)-dependent apoptotic and nonapoptotic responses can be selective activated.
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Affiliation(s)
- Kenneth K Teng
- Department of Medicine, Weill Cornell Medical College, New York, New York 10065, USA
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12
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Schecterson LC, Hudson MP, Ko M, Philippidou P, Akmentin W, Wiley J, Rosenblum E, Chao MV, Halegoua S, Bothwell M. Trk activation in the secretory pathway promotes Golgi fragmentation. Mol Cell Neurosci 2010; 43:403-13. [PMID: 20123019 DOI: 10.1016/j.mcn.2010.01.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 12/28/2009] [Accepted: 01/19/2010] [Indexed: 11/25/2022] Open
Abstract
Activation of nascent receptor tyrosine kinases within the secretory pathway has been reported, yet the consequences of intracellular activation are largely unexplored. We report that overexpression of the Trk neurotrophin receptors causes accumulation of autoactivated receptors in the ER-Golgi intermediate compartment. Autoactivated receptors exhibit inhibited Golgi-mediated processing and they inhibit Golgi-mediated processing of other co-expressed transmembrane proteins, apparently by inducing fragmentation of the Golgi apparatus. Signaling from G protein-coupled receptors is known to induce Trk transactivation. Transactivation of nascent TrkB in hippocampal neurons resulting from exposure to the neuropeptide PACAP caused Golgi fragmentation, whereas BDNF-dependent activation of TrkB did not. TrkB-mediated Golgi fragmentation employs a MEK-dependent signaling pathway resembling that implicated in regulation of Golgi fragmentation in mitotic cells. Neuronal Golgi fragments, in the form of dendritically localized Golgi outposts, are important determinants of dendritic growth and branching. The capacity of transactivated TrkB to enhance neuronal Golgi fragmentation may represent a novel mechanism regulating neural plasticity.
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Doncel-Pérez E, Caballero-Chacón S, Nieto-Sampedro M. Neurosphere cell differentiation to aldynoglia promoted by olfactory ensheathing cell conditioned medium. Glia 2009; 57:1393-409. [DOI: 10.1002/glia.20858] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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14
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Kim T, Hempstead BL. NRH2 is a trafficking switch to regulate sortilin localization and permit proneurotrophin-induced cell death. EMBO J 2009; 28:1612-23. [PMID: 19407813 DOI: 10.1038/emboj.2009.118] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Accepted: 03/30/2009] [Indexed: 12/25/2022] Open
Abstract
Proneurotrophins mediate neuronal apoptosis using a dual receptor complex of sortilin and p75(NTR). Although p75(NTR) is highly expressed on the plasma membrane and accessible to proneurotrophin ligands, sortilin is primarily localized to intracellular membranes, limiting the formation of a cell surface co-receptor complex. Here, we show that the mammalian p75(NTR) homologue NRH2 critically regulates the expression of sortilin on the neuronal cell surface and promotes p75(NTR) and sortilin receptor complex formation, rendering cells responsive to proneurotrophins. This is accomplished by interactions between the cytoplasmic domains of NRH2 and sortilin that impair lysosomal degradation of sortilin. In proneurotrophin-responsive neurons, acute silencing of endogenous NRH2 significantly reduces cell surface-expressed sortilin and abolishes proneurotrophin-induced neuronal death. Thus, these data suggest that NRH2 acts as a trafficking switch to impair lysosomal-dependant sortilin degradation and to redistribute sortilin to the cell surface, rendering p75(NTR)-expressing cells susceptible to proneurotrophin-induced death.
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Affiliation(s)
- Taeho Kim
- Graduate Program in Neuroscience, Weill Medical College of Cornell University, New York, NY 10065, USA
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15
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Wong AW, Willingham M, Xiao J, Kilpatrick TJ, Murray SS. Neurotrophin receptor homolog-2 regulates nerve growth factor signaling. J Neurochem 2008; 106:1964-76. [PMID: 18624909 DOI: 10.1111/j.1471-4159.2008.05539.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The neurotrophin receptor homolog (NRH2) is closely related to the p75 neurotrophin receptor (p75NTR); however, its function and role in neurotrophin signaling are unclear. NRH2 does not bind to nerve growth factor (NGF), however, is able to form a receptor complex with tropomyosin-related kinase receptor A (TrkA) and to generate high-affinity NGF binding sites. Despite this, the mechanisms underpinning the interaction between NRH2 and TrkA remain unknown. Here, we identify that the intracellular domain of NRH2 is required to form an association with TrkA. Our data suggest extensive intracellular interaction between NRH2 and TrkA, as either the juxtamembrane or death domain regions of NRH2 are sufficient for interaction with TrkA. In addition, we demonstrate that TrkA signaling is dramatically influenced by the co-expression of NRH2. Importantly, NRH2 did not influence all downstream TrkA signaling pathways, but rather exerted a specific effect, enhancing src homology 2 domain-containing transforming protein (Shc) activation. Moreover, downstream of Shc, the co-expression of NRH2 resulted in TrkA specifically modulating mitogen-activated protein kinase pathway activation, but not the phosphatidylinositol 3-kinase/Akt pathway. These results indicate that NRH2 utilizes intracellular mechanisms to not only regulate NGF binding to TrkA, but also specifically modulate TrkA receptor signaling, thus adding further layers of complexity and specificity to neurotrophin signaling.
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Affiliation(s)
- Agnes W Wong
- Neurotrophin Signaling Laboratory, The Centre for Neuroscience, The University of Melbourne, Victoria, Australia
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16
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Kenchappa RS, Zampieri N, Chao MV, Barker PA, Teng HK, Hempstead BL, Carter BD. Ligand-Dependent Cleavage of the P75 Neurotrophin Receptor Is Necessary for NRIF Nuclear Translocation and Apoptosis in Sympathetic Neurons. Neuron 2006; 50:219-32. [PMID: 16630834 DOI: 10.1016/j.neuron.2006.03.011] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Revised: 12/15/2005] [Accepted: 03/01/2006] [Indexed: 11/30/2022]
Abstract
The p75 neurotrophin receptor regulates neuronal survival, promoting it in some contexts yet activating apoptosis in others. The mechanism by which the receptor elicits these differential effects is poorly understood. Here, we demonstrate that p75 is cleaved by gamma-secretase in sympathetic neurons, specifically in response to proapoptotic ligands. This cleavage resulted in ubiquitination and subsequent nuclear translocation of NRIF, a DNA binding protein essential for p75-mediated apoptosis. Inhibition of gamma-secretase or expression of a mutant p75 resistant to this protease prevented receptor proteolysis, blocked NRIF nuclear entry, and prevented apoptosis. In contrast, overexpression of the p75 ICD resulted in NRIF nuclear accumulation and apoptosis. The receptor proteolysis and NRIF nuclear localization were also observed in vivo during naturally occurring cell death in the superior cervical ganglia. These results indicate that p75-mediated apoptosis requires gamma-secretase dependent release of its ICD, which facilitates nuclear translocation of NRIF.
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Affiliation(s)
- Rajappa S Kenchappa
- Department of Biochemistry and Center for Molecular Neuroscience, Vanderbilt University Medical School, Nashville, Tennessee 37232, USA
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17
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Abstract
Cells depend for their survival on stimulation by trophic factors and other prosurvival signals, the withdrawal of which induces apoptosis, both via the loss of antiapoptotic signaling and the activation of proapoptotic signaling via specific receptors. These receptors, dubbed dependence receptors, activate apoptotic pathways following the withdrawal of trophic factors and other supportive stimuli. Such receptors may feature in developmental cell death, carcinogenesis (including metastasis), neurodegeneration, and possibly subapoptotic events such as neurite retraction and somal atrophy. Mechanistic studies of dependence receptors suggest that these receptors form ligand-dependent complexes that include specific caspases. Complex formation in the absence of ligand leads to caspase activation by a mechanism that is typically dependent on caspase cleavage of the receptor itself, releasing proapoptotic peptides. Cellular dependence receptors, considered in the aggregate, may thus form a system of molecular integration, analogous to the electrical integration system provided by dendritic arbors in the nervous system.
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Affiliation(s)
- D E Bredesen
- The Buck Institute for Age Research, Novato, CA 94945, USA.
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18
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Kalb R. The protean actions of neurotrophins and their receptors on the life and death of neurons. Trends Neurosci 2005; 28:5-11. [PMID: 15626491 DOI: 10.1016/j.tins.2004.11.003] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
At vanishingly low concentrations, factors of the neurotrophin family (NGF, BDNF, NT3 and NT4/5) can promote neuronal survival or death. Many investigations indicate that the survival-promoting signals of neurotrophins are generated by activation of Trk tyrosine kinase receptors and that their death-promoting signals are generated by activation of p75 neurotrophin receptors (p75(NTR)). Despite this, a body of work indicates that p75(NTR) can promote cell survival and Trk receptors can adversely affect neuron health. The potential mechanisms by which these receptors could have such diverse and antipodal effects are considered here.
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Affiliation(s)
- Robert Kalb
- Joseph Stokes, Jr Research Institute, Children's Hospital of Philadelphia, and Department of Neurology, University of Pennsylvania School of Medicine, 3615 Civic Center Boulevard, Philadelphia, PA 19104, USA.
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19
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Abstract
The cytokine tumor necrosis factor was originally identified as a protein that kills tumor cells. So far, 18 distinct members of this family have been identified. All of them regulate cell survival, proliferation, differentiation, and cell death, also called apoptosis. The apoptosis induced by TNF, and other members of the family, for example, FasL, VEGI, and TRAIL is mediated through death receptors. The apoptotic signals by these cytokines are transduced by eight different death domain- (DD) containing receptors (TNFR1, also called DR1; Fas, also called DR2; DR3, DR4, DR5, DR6, NGFR, and EDAR). The intracellular portion of all these receptors contains a region approximately 80 amino acids long referred to as the "death domain." Upon activation by its ligand, the DD recruits various proteins that mediate both death and proliferation of the cells. These proteins in turn recruit other proteins via their DDs or death effector domains. The actual destruction of the cell, however, is accomplished by serial activation of a family of proteases referred to as caspases. Cell death is negatively regulated by a family of proteins that includes decoy receptors, silencer of DD, sentrin, cellular FLICE inhibitory protein, cellular inhibitors of apoptosis, and survivin. This review is an attempt to describe how these negative and positive players of cell death perform a harmonious dance with each other.
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Affiliation(s)
- Anjana Bhardwaj
- Cytokine Research Laboratory, Department of Bioimmunotherapy, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030, USA
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20
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Murray SS, Perez P, Lee R, Hempstead BL, Chao MV. A novel p75 neurotrophin receptor-related protein, NRH2, regulates nerve growth factor binding to the TrkA receptor. J Neurosci 2004; 24:2742-9. [PMID: 15028767 PMCID: PMC6729530 DOI: 10.1523/jneurosci.3960-03.2004] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Nerve growth factor (NGF) functions as a ligand for two receptors, the TrkA tyrosine kinase receptor and the p75 neurotrophin receptor (p75NTR). The Ig-like domains of Trk receptors and the cysteine-rich repeats of p75NTR are involved in binding to the neurotrophins. Recently, a closely related gene to p75NTR called neurotrophin receptor homolog-2 (NRH2) was identified; however, the function of NRH2 and its relevance to neurotrophin signaling are unclear. NRH2 contains a similar transmembrane and intracellular domain as p75NTR but lacks the characteristic cysteine-rich repeats in the extracellular domain. Here we show that NRH2 is expressed in several neuronal populations that also express p75NTR and Trk receptors. NRH2 does not bind to NGF; however, coimmunoprecipitation experiments demonstrate that NRH2 is capable of interacting with TrkA receptors. Coexpression of NRH2 with TrkA receptors resulted in the formation of high-affinity binding sites for NGF. These results indicate that a transmembrane protein related to p75NTR is capable of modulating Trk receptor binding properties.
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Affiliation(s)
- Simon S Murray
- Skirball Institute of Bimolecular Medicine, New York University School of Medicine, New York, New York 10016, USA.
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21
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Paul CE, Vereker E, Dickson KM, Barker PA. A pro-apoptotic fragment of the p75 neurotrophin receptor is expressed in p75NTRExonIV null mice. J Neurosci 2004; 24:1917-23. [PMID: 14985432 PMCID: PMC6730398 DOI: 10.1523/jneurosci.5397-03.2004] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The p75 neurotrophin receptor (p75NTR) regulates neuronal survival, apoptosis, and growth. Recent studies have reported that disruption of Exon IV produces a null mouse lacking all p75NTR gene products (p75NTRExonIV-/-), whereas mice lacking p75NTR Exon III (p75NTRExonIII-/-) maintain expression of an alternatively spliced form of p75NTR (s-p75NTR). Here, we report that p75NTRExonIV-/- mice express a p75NTR gene product that encodes a truncated protein containing the extracellular stalk region together with the entire transmembrane and intracellular domains. The gene product is initiated from a cryptic Kozak consensus/initiator ATG sequence within a region of Exon IV located 3' to the pGK-Neo insertion site. Overexpression of this fragment in heterologous cells results in activation of Jun kinase and induces Pro-caspase-3 cleavage, indicating that it activates p75NTR signaling cascades. These results indicate that aspects of the p75NTRExonIV-/- phenotype may reflect a gain-of-function mutation rather than loss of p75NTR function.
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Affiliation(s)
- Christine E Paul
- Centre for Neuronal Survival, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada H3A 2B4
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22
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Bredesen DE, Mehlen P, Rabizadeh S. Apoptosis and Dependence Receptors: A Molecular Basis for Cellular Addiction. Physiol Rev 2004; 84:411-30. [PMID: 15044679 DOI: 10.1152/physrev.00027.2003] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Bredesen, Dale E., Patrick Mehlen, and Shahrooz Rabizadeh. Apoptosis and Dependence Receptors: A Molecular Basis for Cellular Addiction. Physiol Rev 84: 411–430, 2004; 10.1152/physrev.00027.2003.—Classical signal transduction is initiated by ligand-receptor interactions. We have described an alternative form of signal transduction that is initiated by the withdrawal of ligands from specific receptors referred to as dependence receptors. This process is widespread, featuring in developmental cell death, carcinogenesis (especially metastasis), neurodegeneration, and possibly subapoptotic events such as neurite retraction and somal atrophy. Initial mechanistic studies of dependence receptors suggest that these receptors form complexes that include specific caspases. Complex formation appears to be a function of ligand-receptor interaction, and dependence receptors appear to exist in at least two conformational states. Complex formation in the absence of ligand leads to caspase activation by a mechanism that in at least some cases is dependent on caspase cleavage of the receptor itself, releasing proapoptotic peptides. Thus these receptors may serve in caspase amplification, and in so doing create cellular states of dependence on their respective ligands.
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Affiliation(s)
- Dale E Bredesen
- The Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945, USA.
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23
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Gentry JJ, Rutkoski NJ, Burke TL, Carter BD. A Functional Interaction between the p75 Neurotrophin Receptor Interacting Factors, TRAF6 and NRIF. J Biol Chem 2004; 279:16646-56. [PMID: 14960584 DOI: 10.1074/jbc.m309209200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Neurotrophin signaling through the p75 receptor regulates apoptosis within the nervous system both during development and in response to injury. Whereas a number of p75 interacting factors have been identified, how these upstream factors function in a coordinated manner to mediate receptor signaling is still unclear. Here, we report a functional interaction between TRAF6 and the neurotrophin receptor interacting factor (NRIF), two proteins known to associate with the intracellular domain of the p75 neurotrophin receptor. The association between NRIF and TRAF6 was direct and occurred with both endogenous and ectopically expressed proteins. A KRAB repressor domain of NRIF and the carboxyl-terminal, receptor-binding region of TRAF6 were required for the interaction. Co-expression of TRAF6 increased the levels of NRIF protein and induced its nuclear translocation. Reciprocally, NRIF enhanced TRAF6-mediated activation of the c-Jun NH2-terminal kinase (JNK) by 3-fold, while only modestly increasing the stimulation of NF-kappaB. The expression of both NRIF and TRAF6 was required for reconstituting p75 activation of JNK in HEK293 cells, whereas NRIF mutants lacking the TRAF6 interaction domain were unable to substitute for the full-length protein in facilitating activation of the kinase. These results suggest that NRIF and TRAF6 functionally interact to facilitate neurotrophin signaling through the p75 receptor.
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Affiliation(s)
- Jennifer J Gentry
- Department of Biochemistry and Center for Molecular Neuroscience, Vanderbilt University Medical School, Nashville, Tennessee 37232, USA
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24
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Proteolytic processing of the p75 neurotrophin receptor and two homologs generates C-terminal fragments with signaling capability. J Neurosci 2003. [PMID: 12843241 DOI: 10.1523/jneurosci.23-13-05425.2003] [Citation(s) in RCA: 192] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The 75 kDa neurotrophin receptor (p75NTR) and two neurotrophin receptor homologs (NRH1, NRH2) constitute a subfamily of the nerve growth factor/tumor necrosis factor receptor superfamily. NRH1 coexists with p75NTR in fish, amphibians, and birds but is absent in mammals, whereas NRH2 exists only in mammals. Unlike p75NTR and NRH1, NRH2 lacks a canonical extracellular ligand binding domain. The similarity of NRH2 to the product of metalloproteinase cleavage of p75NTR prompted us to examine the cleavage of p75NTR in greater detail. p75NTR, NRH1, and NRH2 undergo multiple proteolytic cleavages that ultimately release cytoplasmic fragments. For p75NTR, cleavage in the extracellular domain by a PMA-inducible membrane metalloproteinase is followed by cleavage within or near the transmembrane domain, releasing the intracellular domain into the cytoplasm. This processing resembles the alpha- and gamma-secretase-mediated processing of beta-amyloid precursor protein and the similar processing of Notch. Although neurotrophins did not regulate p75NTR processing, the alpha- and gamma-secretase-mediated cleavage of p75 is modulated by receptor tyrosine kinases (Trks) TrkA and TrkB but not TrkC. Surprisingly, although NRH1 and NRH2 also undergo proteolytic cytoplasmic release of intracellular domains, a different protease mediates the cleavage. Furthermore, whereas the p75NTR soluble intracellular domain accumulates only in the presence of proteasome inhibitors, the equivalent fragment of NRH2 is stable and localizes in the nucleus. Because soluble intracellular domains of p75NTR and NRH2 were found to activate NF-kappaB in concert with TNF receptor associated factor 6 (TRAF6), we propose that cleavage of these proteins may serve conserved cytoplasmic and nuclear signaling functions through distinct proteases.
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25
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Rabizadeh S, Bredesen DE. Ten years on: mediation of cell death by the common neurotrophin receptor p75(NTR). Cytokine Growth Factor Rev 2003; 14:225-39. [PMID: 12787561 DOI: 10.1016/s1359-6101(03)00018-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The common neurotrophin receptor p75(NTR) remains one of the most enigmatic of the tumor necrosis factor receptor (TNFR) superfamily: on the one hand, it displays a death domain and has been shown to be capable of mediating programmed cell death (PCD) upon ligand binding; on the other hand, its death domain is of type II (unlike that of Fas or TNFR I), and it has also been shown to be capable of mediating cell death in response to the withdrawal of ligand. Thus, p75(NTR) may function as a death receptor-similar to Fas or TNFR I-or a dependence receptor-similar to deleted in colorectal cancer (DCC) or uncoordinated gene-5 homologues 1-3 (UNC5H1-3). Here, we review the data relating to the mediation of PCD by p75(NTR), and suggest that one reasonable model for the apparently paradoxical effects of p75(NTR) is that this receptor functions as a "quality control" in that it is capable of mediating PCD in at least four situations: (1). withdrawal of neurotrophins; (2). exposure to mismatched neurotrophins; (3). exposure to unprocessed neurotrophins; and (4). exposure of inappropriately immature cells to neurotrophins. Results to date suggest that these functions are mediated through different underlying mechanisms, and that their respective signaling pathways are cell type and co-receptor dependent.
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Affiliation(s)
- Shahrooz Rabizadeh
- The Buck Institute for Age Research, 8001 Redwood Blvd, Novato, CA 94945-1400, USA.
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Wang X, Shao Z, Zetoune FS, Zeidler MG, Gowrishankar K, Vincenz C. NRADD, a novel membrane protein with a death domain involved in mediating apoptosis in response to ER stress. Cell Death Differ 2003; 10:580-91. [PMID: 12728256 DOI: 10.1038/sj.cdd.4401208] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
NRADD (neurotrophin receptor alike death domain protein) is a novel protein with transmembrane and cytoplasmic regions highly homologous to death receptors, particularly p75(NTR). However, the short N-terminal domain is unique. Expression of NRADD induced apoptosis in a number of cell lines. The apoptotic mechanism involved the activation of caspase-8 and execution of apoptosis without requiring mitochondrial components. The activation of this death receptor-like mechanism required the N-terminal domain, which is N-glycosylated and needed for subcellular targeting. Deletion of the N-terminal domain produced a dominant-negative form of NRADD that protected neurons and Schwann cells from a variety of endoplasmic reticulum (ER) stressors. NRADD may therefore be a necessary component for generating an ER-induced proapoptotic signal.
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Affiliation(s)
- X Wang
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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