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Shanab AY, Mysona BA, Matragoon S, El-Remessy AB. Silencing p75(NTR) prevents proNGF-induced endothelial cell death and development of acellular capillaries in rat retina. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2015; 2:15013. [PMID: 26029724 PMCID: PMC4445004 DOI: 10.1038/mtm.2015.13] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 02/12/2015] [Accepted: 02/13/2015] [Indexed: 12/12/2022]
Abstract
Accumulation of the nerve growth factor precursor (proNGF) and its receptor p75(NTR) have been associated with several neurodegenerative diseases in both brain and retina. However, whether proNGF contributes to microvascular degeneration remain unexplored. This study seeks to investigate the mechanism by which proNGF/p75(NTR) induce endothelial cell (EC) death and development of acellular capillaries, a surrogate marker of retinal ischemia. Stable overexpression of the cleavage-resistant proNGF and molecular silencing of p75(NTR) were utilized in human retinal EC and rat retinas in vivo. Stable overexpression of proNGF decreased NGF levels and induced retinal vascular cell death evident by 1.9-fold increase in acellular capillaries and activation of JNK and cleaved-PARP that were mitigated by p75(NTR)shRNA. In vitro, overexpression of proNGF did not alter TNF-α level, reduced NGF, however induced EC apoptosis evident by activation of JNK and p38 MAPK, cleaved-PARP. Silencing p75(NTR) using siRNA restored expression of NGF and TrkA activation and prevented EC apoptosis. Treatment of EC with human-mutant proNGF induced apoptosis that coincided with marked protein interaction and nuclear translocation of p75(NTR) and the neurotrophin receptor interacting factor. These effects were abolished by a selective p75(NTR) antagonist. Therefore, targeting p75(NTR) represents a potential therapeutic strategy for diseases associated with aberrant expression of proNGF.
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Affiliation(s)
- Ahmed Y Shanab
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia , Georgia, USA ; Culver Vision Discovery Institute, Georgia Regents University , Georgia, USA ; Charlie Norwood Veterans Affairs Medical Center , Augusta, Georgia, USA
| | - Barbara A Mysona
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia , Georgia, USA ; Culver Vision Discovery Institute, Georgia Regents University , Georgia, USA ; Charlie Norwood Veterans Affairs Medical Center , Augusta, Georgia, USA
| | - Suraporn Matragoon
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia , Georgia, USA ; Culver Vision Discovery Institute, Georgia Regents University , Georgia, USA ; Charlie Norwood Veterans Affairs Medical Center , Augusta, Georgia, USA
| | - Azza B El-Remessy
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia , Georgia, USA ; Culver Vision Discovery Institute, Georgia Regents University , Georgia, USA ; Charlie Norwood Veterans Affairs Medical Center , Augusta, Georgia, USA
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Xiong J, Zhou LI, Lim Y, Yang M, Zhu YH, Li ZW, Fu DL, Zhou XF. Mature brain-derived neurotrophic factor and its receptor TrkB are upregulated in human glioma tissues. Oncol Lett 2015; 10:223-227. [PMID: 26171003 DOI: 10.3892/ol.2015.3181] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 04/17/2015] [Indexed: 12/20/2022] Open
Abstract
There are two forms of brain-derived neurotrophic factor (BDNF), precursor of BDNF (proBDNF) and mature BDNF, which each exert opposing effects through two different transmembrane receptor signaling systems, consisting of p75 neurotrophin receptor (p75NTR) and tyrosine receptor kinase B (TrkB). Previous studies have demonstrated that proBDNF promotes cell death and inhibits the growth and migration of C6 glioma cells through p75NTR in vitro, while mature BDNF has opposite effects on C6 glioma cells. It is hypothesized that mature BDNF is essential in the development of malignancy in gliomas. However, histological data obtained in previous studies were unable distinguish mature BDNF from proBDNF due to the lack of specific antibodies. The present study investigated the expression of mature BDNF using a specific sheep monoclonal anti-mature BDNF antibody in 42 human glioma tissues of different grades and 10 control tissues. The correlation between mature BDNF and TrkB was analyzed. Mature BDNF expression was significantly increased in high-grade gliomas, and was positively correlated with the malignancy of the tumor and TrkB receptor expression. The present data have demonstrated that increased levels of mature BDNF contribute markedly to the development of malignancy of human gliomas through the primary BDNF receptor TrkB.
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Affiliation(s)
- Jing Xiong
- Department of Neurology, Second Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650101, P.R. China
| | - L I Zhou
- The First People's Hospital of Yunnan, Kunming, Yunnan 650000, P.R. China
| | - Yoon Lim
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Miao Yang
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Yu-Hong Zhu
- Department of Neurology, Second Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650101, P.R. China
| | - Zhi-Wei Li
- Department of Neurology, Second Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650101, P.R. China
| | - Deng-Li Fu
- Department of Neurology, Second Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650101, P.R. China
| | - Xin-Fu Zhou
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia ; Key Laboratory of Stem Cells and Regenerative Medicine, Institute of Molecular and Clinical Medicine, Kunming Medical University, Kunming, Yunnan 650101, P.R. China
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Vicario A, Kisiswa L, Tann JY, Kelly CE, Ibáñez CF. Neuron-type-specific signaling by the p75NTR death receptor is regulated by differential proteolytic cleavage. J Cell Sci 2015; 128:1507-17. [PMID: 25720379 DOI: 10.1242/jcs.161745] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 02/16/2015] [Indexed: 11/20/2022] Open
Abstract
Signaling by the p75 neurotrophin receptor (p75(NTR), also known as NGFR) is often referred to as cell-context dependent, but neuron-type-specific signaling by p75(NTR) has not been systematically investigated. Here, we report that p75(NTR) signals very differently in hippocampal neurons (HCNs) and cerebellar granule neurons (CGNs), and we present evidence indicating that this is partly controlled by differential proteolytic cleavage. Nerve growth factor (NGF) induced caspase-3 activity and cell death in HCNs but not in CGNs, whereas it stimulated NFκB activity in CGNs but not in HCNs. HCNs and CGNs displayed different patterns of p75(NTR) proteolytic cleavage. Whereas the p75(NTR) carboxy terminal fragment (CTF) was more abundant than the intracellular domain (ICD) in HCNs, CGNs exhibited fully processed ICD with very little CTF. Pharmacological or genetic blockade of p75(NTR) cleavage by γ-secretase abolished NGF-induced upregulation of NFκB activity and enabled induction of CGN death, phenocopying the functional profile of HCNs. Thus, the activities of multifunctional receptors, such as p75(NTR), can be tuned into narrower activity profiles by cell-type-specific differences in intracellular processes, such as proteolytic cleavage, leading to very different biological outcomes.
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Affiliation(s)
- Annalisa Vicario
- Department of Neuroscience, Karolinska Institute, Stockholm S-17177, Sweden
| | - Lilian Kisiswa
- Department of Neuroscience, Karolinska Institute, Stockholm S-17177, Sweden
| | - Jason Y Tann
- Life Sciences Institute, Department of Physiology, National University of Singapore, Singapore 117456, Singapore
| | - Claire E Kelly
- Department of Neuroscience, Karolinska Institute, Stockholm S-17177, Sweden
| | - Carlos F Ibáñez
- Department of Neuroscience, Karolinska Institute, Stockholm S-17177, Sweden Life Sciences Institute, Department of Physiology, National University of Singapore, Singapore 117456, Singapore Department of Physiology, National University of Singapore, Singapore 117597, Singapore
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Gershoni-Emek N, Chein M, Gluska S, Perlson E. Amyotrophic lateral sclerosis as a spatiotemporal mislocalization disease: location, location, location. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 315:23-71. [PMID: 25708461 DOI: 10.1016/bs.ircmb.2014.11.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Spatiotemporal localization of signals is a fundamental feature impacting cell survival and proper function. The cell needs to respond in an accurate manner in both space and time to both intra- and intercellular environment cues. The regulation of this comprehensive process involves the cytoskeleton and the trafficking machinery, as well as local protein synthesis and ligand-receptor mechanisms. Alterations in such mechanisms can lead to cell dysfunction and disease. Motor neurons that can extend over tens of centimeters are a classic example for the importance of such events. Changes in spatiotemporal localization mechanisms are thought to play a role in motor neuron degeneration that occurs in amyotrophic lateral sclerosis (ALS). In this review we will discuss these mechanisms and argue that possible misregulated factors can lead to motor neuron degeneration in ALS.
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Affiliation(s)
- Noga Gershoni-Emek
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Michael Chein
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Shani Gluska
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Eran Perlson
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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Marchetti L, Luin S, Bonsignore F, de Nadai T, Beltram F, Cattaneo A. Ligand-induced dynamics of neurotrophin receptors investigated by single-molecule imaging approaches. Int J Mol Sci 2015; 16:1949-79. [PMID: 25603178 PMCID: PMC4307343 DOI: 10.3390/ijms16011949] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 01/05/2015] [Indexed: 01/14/2023] Open
Abstract
Neurotrophins are secreted proteins that regulate neuronal development and survival, as well as maintenance and plasticity of the adult nervous system. The biological activity of neurotrophins stems from their binding to two membrane receptor types, the tropomyosin receptor kinase and the p75 neurotrophin receptors (NRs). The intracellular signalling cascades thereby activated have been extensively investigated. Nevertheless, a comprehensive description of the ligand-induced nanoscale details of NRs dynamics and interactions spanning from the initial lateral movements triggered at the plasma membrane to the internalization and transport processes is still missing. Recent advances in high spatio-temporal resolution imaging techniques have yielded new insight on the dynamics of NRs upon ligand binding. Here we discuss requirements, potential and practical implementation of these novel approaches for the study of neurotrophin trafficking and signalling, in the framework of current knowledge available also for other ligand-receptor systems. We shall especially highlight the correlation between the receptor dynamics activated by different neurotrophins and the respective signalling outcome, as recently revealed by single-molecule tracking of NRs in living neuronal cells.
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Affiliation(s)
- Laura Marchetti
- National Enterprise for nanoScience and nanoTechnology (NEST) Laboratory, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12, Pisa I-56127, Italy.
| | - Stefano Luin
- National Enterprise for nanoScience and nanoTechnology (NEST) Laboratory, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12, Pisa I-56127, Italy.
| | - Fulvio Bonsignore
- National Enterprise for nanoScience and nanoTechnology (NEST) Laboratory, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12, Pisa I-56127, Italy.
| | - Teresa de Nadai
- Biology Laboratory (BioSNS), Scuola Normale Superiore and Istituto di Neuroscienze-CNR, via Moruzzi 1, Pisa I-56100, Italy.
| | - Fabio Beltram
- National Enterprise for nanoScience and nanoTechnology (NEST) Laboratory, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12, Pisa I-56127, Italy.
| | - Antonino Cattaneo
- Biology Laboratory (BioSNS), Scuola Normale Superiore and Istituto di Neuroscienze-CNR, via Moruzzi 1, Pisa I-56100, Italy.
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56
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Ahmad I, Yue WY, Fernando A, Clark JJ, Woodson EA, Hansen MR. p75NTR is highly expressed in vestibular schwannomas and promotes cell survival by activating nuclear transcription factor κB. Glia 2014; 62:1699-712. [PMID: 24976126 PMCID: PMC4150679 DOI: 10.1002/glia.22709] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 06/03/2014] [Accepted: 06/06/2014] [Indexed: 01/08/2023]
Abstract
Vestibular schwannomas (VSs) arise from Schwann cells (SCs) and result from the loss of function of merlin, the protein product of the NF2 tumor suppressor gene. In contrast to non-neoplastic SCs, VS cells survive long-term in the absence of axons. We find that p75(NTR) is overexpressed in VSs compared with normal nerves, both at the transcript and protein level, similar to the response of non-neoplastic SCs following axotomy. Despite elevated p75(NTR) expression, VS cells are resistant to apoptosis due to treatment with proNGF, a high affinity ligand for p75(NTR) . Furthermore, treatment with proNGF protects VS cells from apoptosis due to c-Jun N-terminal kinase (JNK) inhibition indicating that p75(NTR) promotes VS cell survival. Treatment of VS cells with proNGF activated NF-κB while inhibition of JNK with SP600125 or siRNA-mediated knockdown reduced NF-κB activity. Significantly, proNGF also activated NF-κB in cultures treated with JNK inhibitors. Thus, JNK activity appears to be required for basal levels of NF-κB activity but not for proNGF-induced NF-κB activity. To confirm that the increase in NF-κB activity contributes to the prosurvival effect of proNGF, we infected VS cultures with Ad.IκB.SerS32/36A virus, which inhibits NF-κB activation. Compared with control virus, Ad.IκB.SerS32/36A significantly increased apoptosis including in VS cells treated with proNGF. Thus, in contrast to non-neoplastic SCs, p75(NTR) signaling provides a prosurvival response in VS cells by activating NF-κB independent of JNK. Such differences may contribute to the ability of VS cells to survive long-term in the absence of axons.
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Affiliation(s)
- Iram Ahmad
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa 52242
| | - Wei Ying Yue
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa 52242
- Department of Otolaryngology-HNS, Mayo Clinic, Rochester, MN
| | - Augusta Fernando
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa 52242
- Department of Otolaryngology-HNS, Northwestern University, Chicago, IL
| | - J. Jason Clark
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa 52242
| | - Erika A. Woodson
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa 52242
- Department of Otolaryngology-HNS, Cleveland Clinic, Cleveland, OH
| | - Marlan R. Hansen
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa 52242
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57
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Larios JA, Jausoro I, Benitez ML, Bronfman FC, Marzolo MP. Neurotrophins regulate ApoER2 proteolysis through activation of the Trk signaling pathway. BMC Neurosci 2014; 15:108. [PMID: 25233900 PMCID: PMC4177048 DOI: 10.1186/1471-2202-15-108] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Accepted: 09/15/2014] [Indexed: 12/27/2022] Open
Abstract
Background ApoER2 and the neurotrophin receptors Trk and p75NTR are expressed in the CNS and regulate key functional aspects of neurons, including development, survival, and neuronal function. It is known that both ApoER2 and p75NTR are processed by metalloproteinases, followed by regulated intramembrane proteolysis. TrkA activation by nerve growth factor (NGF) increases the proteolytic processing of p75NTR mediated by ADAM17. Reelin induces the sheeding of ApoER2 ectodomain depending on metalloproteinase activity. However, it is not known if there is a common regulation mechanism for processing these receptors. Results We found that TrkA activation by NGF in PC12 cells induced ApoER2 processing, which was dependent on TrkA activation and metalloproteinases. NGF-induced ApoER2 proteolysis was independent of mitogen activated protein kinase activity and of phosphatidylinositol-3 kinase activity. In contrast, the basal proteolysis of ApoER2 increased when both kinases were pharmacologically inhibited. The ApoER2 ligand reelin regulated the proteolytic processing of its own receptor but not of p75NTR. Finally, in primary cortical neurons, which express both ApoER2 and TrkB, we found that the proteolysis of ApoER2 was also regulated by brain-derived growth factor (BDNF). Conclusions Our results highlight a novel relationship between neurotrophins and the reelin-ApoER2 system, suggesting that these two pathways might be linked to regulate brain development, neuronal survival, and some pathological conditions.
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Affiliation(s)
| | | | | | | | - Maria-Paz Marzolo
- Departamento de Biología Celular y Molecular, Laboratorio de Tráfico Intracelular y Señalización, Facultad de Ciencias Biológicas, Pontificia Universidad Católica, Alameda 340, Santiago 8320000, Chile.
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58
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Kraemer BR, Snow JP, Vollbrecht P, Pathak A, Valentine WM, Deutch AY, Carter BD. A role for the p75 neurotrophin receptor in axonal degeneration and apoptosis induced by oxidative stress. J Biol Chem 2014; 289:21205-16. [PMID: 24939843 PMCID: PMC4118083 DOI: 10.1074/jbc.m114.563403] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 06/10/2014] [Indexed: 12/14/2022] Open
Abstract
The p75 neurotrophin receptor (p75(NTR)) mediates the death of specific populations of neurons during the development of the nervous system or after cellular injury. The receptor has also been implicated as a contributor to neurodegeneration caused by numerous pathological conditions. Because many of these conditions are associated with increases in reactive oxygen species, we investigated whether p75(NTR) has a role in neurodegeneration in response to oxidative stress. Here we demonstrate that p75(NTR) signaling is activated by 4-hydroxynonenal (HNE), a lipid peroxidation product generated naturally during oxidative stress. Exposure of sympathetic neurons to HNE resulted in neurite degeneration and apoptosis. However, these effects were reduced markedly in neurons from p75(NTR-/-) mice. The neurodegenerative effects of HNE were not associated with production of neurotrophins and were unaffected by pretreatment with a receptor-blocking antibody, suggesting that oxidative stress activates p75(NTR) via a ligand-independent mechanism. Previous studies have established that proteolysis of p75(NTR) by the metalloprotease TNFα-converting enzyme and γ-secretase is necessary for p75(NTR)-mediated apoptotic signaling. Exposure of sympathetic neurons to HNE resulted in metalloprotease- and γ-secretase-dependent cleavage of p75(NTR). Pharmacological blockade of p75(NTR) proteolysis protected sympathetic neurons from HNE-induced neurite degeneration and apoptosis, suggesting that cleavage of p75(NTR) is necessary for oxidant-induced neurodegeneration. In vivo, p75(NTR-/-) mice exhibited resistance to axonal degeneration associated with oxidative injury following administration of the neurotoxin 6-hydroxydopamine. Together, these data suggest a novel mechanism linking oxidative stress to ligand-independent cleavage of p75(NTR), resulting in axonal fragmentation and neuronal death.
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Affiliation(s)
| | | | | | | | - William M Valentine
- Pathology, Microbiology, and Immunology, the Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN 37232
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Mysona BA, Shanab AY, Elshaer SL, El-Remessy AB. Nerve growth factor in diabetic retinopathy: beyond neurons. EXPERT REVIEW OF OPHTHALMOLOGY 2014; 9:99-107. [PMID: 25031607 PMCID: PMC4096131 DOI: 10.1586/17469899.2014.903157] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Diabetic retinopathy (DR), a major ocular complication of diabetes, is a leading cause of blindness in US working age adults with limited treatments. Neurotrophins (NTs), a family of proteins essential for growth, differentiation and survival of retinal neurons, have emerged as potential players in the pathogenesis of DR. NTs can signal through their corresponding tropomyosin kinase related receptor to mediate cell survival or through the p75 neurotrophin receptor with the co-receptor, sortilin, to mediate cell death. This review focuses on the role of NGF, the first discovered NT, in the development of DR. Impaired processing of proNGF has been found in ocular fluids from diabetic patients as well as experimental models. Evidence from literature and our studies support the notion that NTs appear to play multiple potential roles in DR, hence, understanding their contribution to DR may lead to promising therapeutic approaches for this devastating disease.
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Affiliation(s)
- Barbara A Mysona
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, USA and Culver Vision Discovery Institute, Georgia Regents University, Augusta, GA, USA and Charlie Norwood Veterans Affairs Medical Center, Augusta, GA, USA
| | - Ahmed Y Shanab
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, USA and Culver Vision Discovery Institute, Georgia Regents University, Augusta, GA, USA and Charlie Norwood Veterans Affairs Medical Center, Augusta, GA, USA
| | - Sally L Elshaer
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, USA and Culver Vision Discovery Institute, Georgia Regents University, Augusta, GA, USA and Charlie Norwood Veterans Affairs Medical Center, Augusta, GA, USA
| | - Azza B El-Remessy
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, USA and Culver Vision Discovery Institute, Georgia Regents University, Augusta, GA, USA and Charlie Norwood Veterans Affairs Medical Center, Augusta, GA, USA
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60
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Escudero CA, Lazo OM, Galleguillos C, Parraguez JI, Lopez-Verrilli MA, Cabeza C, Leon L, Saeed U, Retamal C, Gonzalez A, Marzolo MP, Carter BD, Court FA, Bronfman FC. The p75 neurotrophin receptor evades the endolysosomal route in neuronal cells, favouring multivesicular bodies specialised for exosomal release. J Cell Sci 2014; 127:1966-79. [PMID: 24569882 DOI: 10.1242/jcs.141754] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The p75 neurotrophin receptor (p75, also known as NGFR) is a multifaceted signalling receptor that regulates neuronal physiology, including neurite outgrowth, and survival and death decisions. A key cellular aspect regulating neurotrophin signalling is the intracellular trafficking of their receptors; however, the post-endocytic trafficking of p75 is poorly defined. We used sympathetic neurons and rat PC12 cells to study the mechanism of internalisation and post-endocytic trafficking of p75. We found that p75 internalisation depended on the clathrin adaptor protein AP2 and on dynamin. More surprisingly, p75 evaded the lysosomal route at the level of the early endosome, instead accumulating in two different types of endosomes, Rab11-positive endosomes and multivesicular bodies (MVBs) positive for CD63, a marker of the exosomal pathway. Consistently, depolarisation by KCl induced the liberation of previously endocytosed full-length p75 into the extracellular medium in exosomes. Thus, p75 defines a subpopulation of MVBs that does not mature to lysosomes and is available for exosomal release by neuronal cells.
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Affiliation(s)
- Claudia A Escudero
- Faculty of Biological Sciences, Physiology Department, Pontificia Universidad Católica, Santiago, CP 8331010, Chile
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61
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Forsyth PA, Krishna N, Lawn S, Valadez JG, Qu X, Fenstermacher DA, Fournier M, Potthast L, Chinnaiyan P, Gibney GT, Zeinieh M, Barker PA, Carter BD, Cooper MK, Kenchappa RS. p75 neurotrophin receptor cleavage by α- and γ-secretases is required for neurotrophin-mediated proliferation of brain tumor-initiating cells. J Biol Chem 2014; 289:8067-85. [PMID: 24519935 DOI: 10.1074/jbc.m113.513762] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Malignant gliomas are highly invasive, proliferative, and resistant to treatment. Previously, we have shown that p75 neurotrophin receptor (p75NTR) is a novel mediator of invasion of human glioma cells. However, the role of p75NTR in glioma proliferation is unknown. Here we used brain tumor-initiating cells (BTICs) and show that BTICs express neurotrophin receptors (p75NTR, TrkA, TrkB, and TrkC) and their ligands (NGF, brain-derived neurotrophic factor, and neurotrophin 3) and secrete NGF. Down-regulation of p75NTR significantly decreased proliferation of BTICs. Conversely, exogenouous NGF stimulated BTIC proliferation through α- and γ-secretase-mediated p75NTR cleavage and release of its intracellular domain (ICD). In contrast, overexpression of the p75NTR ICD induced proliferation. Interestingly, inhibition of Trk signaling blocked NGF-stimulated BTIC proliferation and p75NTR cleavage, indicating a role of Trk in p75NTR signaling. Further, blocking p75NTR cleavage attenuated Akt activation in BTICs, suggesting role of Akt in p75NTR-mediated proliferation. We also found that p75NTR, α-secretases, and the four subunits of the γ-secretase enzyme were elevated in glioblastoma multiformes patients. Importantly, the ICD of p75NTR was commonly found in malignant glioma patient specimens, suggesting that the receptor is activated and cleaved in patient tumors. These results suggest that p75NTR proteolysis is required for BTIC proliferation and is a novel potential clinical target.
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Affiliation(s)
- Peter A Forsyth
- From the Department of Neuro-Oncology, Moffitt Cancer Center and Research Institute and
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62
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Chen ZX, Wallis K, Fell SM, Sobrado VR, Hemmer MC, Ramsköld D, Hellman U, Sandberg R, Kenchappa RS, Martinson T, Johnsen JI, Kogner P, Schlisio S. RNA helicase A is a downstream mediator of KIF1Bβ tumor-suppressor function in neuroblastoma. Cancer Discov 2014; 4:434-51. [PMID: 24469107 DOI: 10.1158/2159-8290.cd-13-0362] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
UNLABELLED Inherited KIF1B loss-of-function mutations in neuroblastomas and pheochromocytomas implicate the kinesin KIF1B as a 1p36.2 tumor suppressor. However, the mechanism of tumor suppression is unknown. We found that KIF1B isoform β (KIF1Bβ) interacts with RNA helicase A (DHX9), causing nuclear accumulation of DHX9, followed by subsequent induction of the proapoptotic XIAP-associated factor 1 (XAF1) and, consequently, apoptosis. Pheochromocytoma and neuroblastoma arise from neural crest progenitors that compete for growth factors such as nerve growth factor (NGF) during development. KIF1Bβ is required for developmental apoptosis induced by competition for NGF. We show that DHX9 is induced by and required for apoptosis stimulated by NGF deprivation. Moreover, neuroblastomas with chromosomal deletion of 1p36 exhibit loss of KIF1Bβ expression and impaired DHX9 nuclear localization, implicating the loss of DHX9 nuclear activity in neuroblastoma pathogenesis. SIGNIFICANCE KIF1Bβ has neuroblastoma tumor-suppressor properties and promotes and requires nuclear-localized DHX9 for its apoptotic function by activating XAF1 expression. Loss of KIF1Bβ alters subcellular localization of DHX9 and diminishes NGF dependence of sympathetic neurons, leading to reduced culling of neural progenitors, and, therefore, might predispose to tumor formation.
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Affiliation(s)
- Zhi Xiong Chen
- 1Ludwig Institute for Cancer Research Ltd.; 2Department of Cell and Molecular Biology, Karolinska Institutet; 3Department of Women's and Children's Health, Karolinska University Hospital, Stockholm; 4Ludwig Institute for Cancer Research Ltd., Biomedical Center, Uppsala; 5Department of Clinical Genetics, Institute of Biomedicine, University of Gothenburg, Sahlgrenska University Hospital, Göteborg, Sweden; and 6Moffitt Cancer Center, Neuro-Oncology Program, Tampa, Florida
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63
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Kraemer BR, Yoon SO, Carter BD. The biological functions and signaling mechanisms of the p75 neurotrophin receptor. Handb Exp Pharmacol 2014; 220:121-164. [PMID: 24668472 DOI: 10.1007/978-3-642-45106-5_6] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The p75 neurotrophin receptor (p75(NTR)) regulates a wide range of cellular functions, including programmed cell death, axonal growth and degeneration, cell proliferation, myelination, and synaptic plasticity. The multiplicity of cellular functions governed by the receptor arises from the variety of ligands and co-receptors which associate with p75(NTR) and regulate its signaling. P75(NTR) promotes survival through interactions with Trk receptors, inhibits axonal regeneration via partnerships with Nogo receptor (Nogo-R) and Lingo-1, and promotes apoptosis through association with Sortilin. Signals downstream of these interactions are further modulated through regulated intramembrane proteolysis (RIP) of p75(NTR) and by interactions with numerous cytosolic partners. In this chapter, we discuss the intricate signaling mechanisms of p75(NTR), emphasizing how these signals are differentially regulated to mediate these diverse cellular functions.
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Affiliation(s)
- B R Kraemer
- Department of Biochemistry, Vanderbilt University School of Medicine, 625 Light Hall, Nashville, TN, 37232, USA
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64
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Verge VMK, Andreassen CS, Arnason TG, Andersen H. Mechanisms of disease: role of neurotrophins in diabetes and diabetic neuropathy. HANDBOOK OF CLINICAL NEUROLOGY 2014; 126:443-60. [PMID: 25410238 DOI: 10.1016/b978-0-444-53480-4.00032-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Neuropathy is an insidious and devastating consequence of diabetes. Early studies provided a strong rationale for deficient neurotrophin support in the pathogenesis of diabetic neuropathy in a number of critical tissues and organs. It has now been over a decade since the first failed human neurotrophin supplementation clinical trials, but mounting evidence still implicates these trophic factors in diabetic neuropathy. Since then, tremendous advances have been made in our understanding of the complexities of neurotrophin signaling and processing and how the diabetic milieu might impact this. This in turn changes both our perception of how the altered trophic environment contributes to the etiology of diabetic neuropathy and the design of future neurotrophin therapeutic interventions. This chapter summarizes some of these findings and attempts to integrate neurotrophin actions on the nervous system with an increasing appreciation of their role in the regulation of metabolic processes in diabetes that impact the diabetic neuropathic state.
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Affiliation(s)
- Valerie M K Verge
- Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, Canada; Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon City Hospital, Saskatoon, Canada.
| | - Christer S Andreassen
- Department of Otorhinolaryngology and Head and Neck Surgery, Aarhus University Hospital, Aarhus, Denmark
| | - Terra G Arnason
- Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, Canada; Department of Medicine, Division of Endocrinology and Metabolism, University of Saskatchewan, Saskatoon, Canada
| | - Henning Andersen
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
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65
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Abstract
The sortilin family of Vps10p-domain receptors includes sortilin, SorLA, and SorCS1-3. These type-I transmembrane receptors predominate in distinct neuronal tissues, but expression is also present in certain specialized non-neuronal cell populations including hepatocytes and cells of the immune system. The biology of sortilins is complex as they participate in both cell signaling and in intracellular protein sorting. Sortilins function physiologically in signaling by pro- and mature neurotrophins in neuronal viability and functionality. Recent genome-wide association studies have linked members to neurological disorders such as Alzheimer's disease and bipolar disorder and outside the nervous system to development of coronary artery disease and type-2 diabetes. Particularly well described are the receptor functions in neuronal signaling by pro- (proNT) and mature (NT) neurotrophins and in the processing/metabolism of amyloid precursor protein (APP).
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Affiliation(s)
- S Glerup
- Danish Research Institute of Translational Neuroscience DANDRITE, Nordic EMBL Partnership, and The Lundbeck Foundation Research Center MIND, Department of Biomedicine, University of Aarhus, Ole Worms Allé 3, 8000, Aarhus C, Denmark
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66
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Abstract
Like most growth factors, neurotrophins are initially synthesized as precursors that are cleaved to release C-terminal mature forms. The well-characterized mature neurotrophins bind to Trk receptors to initiate survival and differentiative responses. More recently, the precursor forms or proneurotrophins have been found to act as distinct ligands by binding to an unrelated receptor complex consisting of the p75 neurotrophin receptor (p75) and sortilin to initiate cell death. Induction of proNGF and p75 has been observed in preclinical injury models and in pathological states in the central nervous system, and strategies that block the proNGF/p75 interaction are effective in limiting neuronal apoptosis. In contrast, the mechanisms that regulate expression of other proneurotrophins, including proBDNF and proNT-3, are less well understood. Here, recent findings on the biological actions, regulation of expression, and pathophysiological effects of proneurotrophins will be reviewed.
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Affiliation(s)
- B L Hempstead
- Department of Medicine, Weill Cornell Medical College, Room C610, 1300 York Ave, New York, NY, 10065, USA,
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67
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Ceni C, Unsain N, Zeinieh MP, Barker PA. Neurotrophins in the regulation of cellular survival and death. Handb Exp Pharmacol 2014; 220:193-221. [PMID: 24668474 DOI: 10.1007/978-3-642-45106-5_8] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The neurotrophins play crucial roles regulating survival and apoptosis in the developing and injured nervous system. The four neurotrophins exert profound and crucial survival effects on developing peripheral neurons, and their expression and action is intimately tied to successful innervation of peripheral targets. In the central nervous system, they are dispensable for neuronal survival during development but support neuronal survival after lesion or other forms of injury. Neurotrophins also regulate apoptosis of both peripheral and central neurons, and we now recognize that there are regulatory advantages to having the same molecules regulate life and death decisions. This chapter examines the biological contexts in which these events take place and highlights the specific ligands, receptors, and signaling mechanisms that allow them to occur.
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Affiliation(s)
- Claire Ceni
- Centre for Neuronal Survival, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, QC, Canada, H3A 2B4
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68
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Spatiotemporal intracellular dynamics of neurotrophin and its receptors. Implications for neurotrophin signaling and neuronal function. Handb Exp Pharmacol 2014; 220:33-65. [PMID: 24668469 DOI: 10.1007/978-3-642-45106-5_3] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Neurons possess a polarized morphology specialized to contribute to neuronal networks, and this morphology imposes an important challenge for neuronal signaling and communication. The physiology of the network is regulated by neurotrophic factors that are secreted in an activity-dependent manner modulating neuronal connectivity. Neurotrophins are a well-known family of neurotrophic factors that, together with their cognate receptors, the Trks and the p75 neurotrophin receptor, regulate neuronal plasticity and survival and determine the neuronal phenotype in healthy and regenerating neurons. Is it now becoming clear that neurotrophin signaling and vesicular transport are coordinated to modify neuronal function because disturbances of vesicular transport mechanisms lead to disturbed neurotrophin signaling and to diseases of the nervous system. This chapter summarizes our current understanding of how the regulated secretion of neurotrophin, the distribution of neurotrophin receptors in different locations of neurons, and the intracellular transport of neurotrophin-induced signaling in distal processes are achieved to allow coordinated neurotrophin signaling in the cell body and axons.
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69
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Mysona BA, Al-Gayyar MMH, Matragoon S, Abdelsaid MA, El-Azab MF, Saragovi HU, El-Remessy AB. Modulation of p75(NTR) prevents diabetes- and proNGF-induced retinal inflammation and blood-retina barrier breakdown in mice and rats. Diabetologia 2013; 56:2329-39. [PMID: 23918145 PMCID: PMC3791887 DOI: 10.1007/s00125-013-2998-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 07/02/2013] [Indexed: 12/16/2022]
Abstract
AIMS/HYPOTHESIS Diabetic retinopathy is characterised by early blood-retina barrier (BRB) breakdown and neurodegeneration. Diabetes causes imbalance of nerve growth factor (NGF), leading to accumulation of the NGF precursor (proNGF), as well as the NGF receptor, p75 neurotrophin receptor (p75(NTR)), suggesting a possible pathological role of the proNGF-p75(NTR) axis in the diabetic retina. To date, the role of this axis in diabetes-induced retinal inflammation and BRB breakdown has not been explored. We hypothesised that modulating p75(NTR) would prevent diabetes- and proNGF-induced retinal inflammation and BRB breakdown. METHODS Diabetes was induced by streptozotocin in wild-type and p75(NTR) knockout (p75KO) mice. After 5 weeks, the expression of inflammatory mediators, ganglion cell loss and BRB breakdown were determined. Cleavage-resistant proNGF was overexpressed in rodent retinas with and without p75(NTR) short hairpin RNA or with pharmacological inhibitors. In vitro, the effects of proNGF were investigated in retinal Müller glial cell line (rMC-1) and primary Müller cells. RESULTS Deletion of p75(NTR) blunted the diabetes-induced decrease in retinal NGF expression and increases in proNGF, nuclear factor κB (NFκB), p-NFκB and TNF-α. Deletion of p75(NTR) also abrogated diabetes-induced glial fibrillary acidic protein expression, ganglion cell loss and vascular permeability. Inhibited expression or cleavage of p75(NTR) blunted proNGF-induced retinal inflammation and vascular permeability. In vitro, proNGF induced p75(NTR)-dependent production of inflammatory mediators in primary wild-type Müller and rMC-1 cultures, but not in p75KO Müller cells. CONCLUSIONS/INTERPRETATION The proNGF-p75(NTR) axis contributes to retinal inflammation and vascular dysfunction in the rodent diabetic retina. These findings underscore the importance of p75(NTR) as a novel regulator of inflammation and potential therapeutic target in diabetic retinopathy.
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Affiliation(s)
- Barbara A Mysona
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, 1120 15th Street HM-1200, Augusta, GA 30912, USA
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70
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Xiong J, Zhou L, Lim Y, Yang M, Zhu YH, Li ZW, Zhou FH, Xiao ZC, Zhou XF. Mature BDNF promotes the growth of glioma cells in vitro. Oncol Rep 2013; 30:2719-24. [PMID: 24064679 DOI: 10.3892/or.2013.2746] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 08/26/2013] [Indexed: 11/06/2022] Open
Abstract
High-grade glioma is incurable and is associated with a short survival time and a poor prognosis. There are two forms of brain-derived neurotrophic factor (BDNF), proBDNF and mature BDNF, which exert opposite effects. Their diverse actions are mediated through two different transmembrane receptor signalling systems: p75NTR and TrkB. The important roles of the BDNF/TrkB signalling system in tumour cell proliferation and survival have been demonstrated. However, few studies have been able to distinguish mature BDNF from proBDNF due to the limitation of specific antibodies. Using specific proBDNF antibodies, we demonstrated that the proBDNF/p75NTR pathway appears to inhibit malignant glioma cell growth and migration. In the present study using specific mature BDNF antibodies, we found that mature BDNF inhibited C6 glioma cell apoptosis and increased cell growth and migration in vitro. Our data suggest that the counterbalance between mature BDNF and proBDNF may regulate tumour growth.
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Affiliation(s)
- Jing Xiong
- Key Laboratory of Stem Cells and Regenerative Medicine, Institute of Molecular and Clinical Medicine, Kunming Medical University, Kunming, Yunnan, P.R. China
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71
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Implementing neuronal plasticity in NeuroAIDS: the experience of brain-derived neurotrophic factor and other neurotrophic factors. J Neuroimmune Pharmacol 2013; 9:80-91. [PMID: 23832285 DOI: 10.1007/s11481-013-9488-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 06/26/2013] [Indexed: 12/16/2022]
Abstract
Human immunodeficiency virus type-1 (HIV) causes mild or severe neurological problems, termed HIV-associated neurocognitive disorder (HAND), even when HIV patients receive antiretroviral therapy. Thus, novel adjunctive therapies are necessary to reduce or abolish the neurotoxic effect of HIV. However, new therapies require a better understanding of the molecular and cellular mechanisms of HIV-induced neurotoxicity. HAND subjects are characterized by being profoundly depressed, and they experience deficits in memory, learning and movements. Experimental evidence has also shown that HIV reduces neurogenesis. These deficits resemble those occurring in premature brain aging or in a brain with impaired neural repair properties. Thus, it appears that HIV diminishes neuronal survival, along with reduced neuronal connections. These two phenomena should not occur in the adult and developing brain when synaptic plasticity is promoted by neurotrophic factors, polypeptides that are present in adult synapses. This review will outline experimental evidence as well as present emerging concepts for the use of neurotrophic factors and in particular brain-derived neurotrophic factor as an adjunct therapy to prevent HIV-mediated neuronal degeneration and restore the loss of synaptic connections.
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72
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Howard L, Wyatt S, Nagappan G, Davies AM. ProNGF promotes neurite growth from a subset of NGF-dependent neurons by a p75NTR-dependent mechanism. Development 2013; 140:2108-17. [PMID: 23633509 PMCID: PMC3640218 DOI: 10.1242/dev.085266] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/21/2013] [Indexed: 01/19/2023]
Abstract
The somatosensory and sympathetic innervation of the vertebrate head is derived principally from the neurons of trigeminal and superior cervical ganglia (SCG), respectively. During development, the survival of both populations of neurons and the terminal growth and branching of their axons in the tissues they innervate is regulated by the supply of nerve growth factor (NGF) produced by these tissues. NGF is derived by proteolytic cleavage of a large precursor protein, proNGF, which is recognised to possess distinctive biological functions. Here, we show that proNGF promotes profuse neurite growth and branching from cultured postnatal mouse SCG neurons. In marked contrast, proNGF does not promote the growth of trigeminal neurites. Studies using compartment cultures demonstrated that proNGF acts locally on SCG neurites to promote growth. The neurite growth-promoting effect of proNGF is not observed in SCG neurons cultured from p75(NTR)-deficient mice, and proNGF does not phosphorylate the NGF receptor tyrosine kinase TrkA. These findings suggest that proNGF selectively promotes the growth of neurites from a subset of NGF-responsive neurons by a p75(NTR)-dependent mechanism during postnatal development when the axons of these neurons are ramifying within their targets in vivo.
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Affiliation(s)
- Laura Howard
- Molecular Biosciences Division, School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AT, Wales, UK.
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73
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Avdoshina V, Bachis A, Mocchetti I. Synaptic dysfunction in human immunodeficiency virus type-1-positive subjects: inflammation or impaired neuronal plasticity? J Intern Med 2013; 273:454-65. [PMID: 23600400 PMCID: PMC3633109 DOI: 10.1111/joim.12050] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Many people infected with the human immunodeficiency virus type-1 (HIV) exhibit mild or severe neurological problems, termed HIV-associated neurocognitive disorder (HAND), even when receiving antiretroviral therapy. Thus, novel adjunctive therapies must be developed to overcome the neurotoxic effect of HIV. New therapies require a better understanding of the molecular and cellular mechanisms of HIV-induced neurotoxicity and the risk factors that, besides inflammation and T-cell depletion and drugs of abuse, render the central nervous system (CNS) a target of HIV-induced neurotoxicity. HIV appears to impair neuronal plasticity, which refers to the innate ability of the CNS respond to injury and promote recovery of function. The availability of brain-derived neurotrophic factor (BDNF), a potent neurotrophic factor that is present in abundance in the adult brain, is essential for neuronal plasticity. BDNF acts through a receptor system composed of Trk and p75NTR. Here, we present experimental evidence that some of the clinical features of HIV-mediated neurological impairment could result from altered BDNF/TrkB/p75NTR regulation and function.
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Affiliation(s)
- V Avdoshina
- Laboratory of Preclinical Neurobiology, Department of Neuroscience, Georgetown University Medical Center, Washington, DC, USA
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74
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Matusica D, Skeldal S, Sykes AM, Palstra N, Sharma A, Coulson EJ. An intracellular domain fragment of the p75 neurotrophin receptor (p75(NTR)) enhances tropomyosin receptor kinase A (TrkA) receptor function. J Biol Chem 2013; 288:11144-54. [PMID: 23471969 PMCID: PMC3630867 DOI: 10.1074/jbc.m112.436469] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 02/17/2013] [Indexed: 11/06/2022] Open
Abstract
Facilitation of nerve growth factor (NGF) signaling by the p75 neurotrophin receptor (p75(NTR)) is critical for neuronal survival and differentiation. However, the interaction between p75(NTR) and TrkA receptors required for this activity is not understood. Here, we report that a specific 29-amino acid peptide derived from the intracellular domain fragment of p75(NTR) interacts with and potentiates binding of NGF to TrkA-expressing cells, leading to increased neurite outgrowth in sympathetic neurons as a result of enhanced Erk1/2 and Akt signaling. An endogenous intracellular domain fragment of p75(NTR) (p75(ICD)) containing these 29 amino acids is produced by regulated proteolysis of the full-length receptor. We demonstrate that generation of this fragment is a requirement for p75(NTR) to facilitate TrkA signaling in neurons and propose that the juxtamembrane region of p75(ICD) acts to cause a conformational change within the extracellular domain of TrkA. This finding provides new insight into the mechanism by which p75(NTR) and TrkA interact to enhance neurotrophic signaling.
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Affiliation(s)
- Dusan Matusica
- From the Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Sune Skeldal
- From the Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Alex M. Sykes
- From the Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Nickless Palstra
- From the Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Aanchal Sharma
- From the Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Elizabeth J. Coulson
- From the Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
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75
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Xiong J, Zhou L, Yang M, Lim Y, Zhu YH, Fu DL, Li ZW, Zhong JH, Xiao ZC, Zhou XF. ProBDNF and its receptors are upregulated in glioma and inhibit the growth of glioma cells in vitro. Neuro Oncol 2013; 15:990-1007. [PMID: 23576602 DOI: 10.1093/neuonc/not039] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND High-grade glioma is incurable, with a short survival time and poor prognosis. The increased expression of p75 neurotrophin receptor (NTR) is a characteristic of high-grade glioma, but the potential significance of increased p75NTR in this tumor is not fully understood. Since p75NTR is the receptor for the precursor of brain-derived neurotrophic factor (proBDNF), it is suggested that proBDNF may have an impact on glioma. METHODS In this study we investigated the expression of proBDNF and its receptors p75NTR and sortilin in 52 cases of human glioma and 13 cases of controls by immunochemistry, quantitative real-time PCR, and Western blot methods. Using C6 glioma cells as a model, we investigated the roles of proBDNF on C6 glioma cell differentiation, growth, apoptosis, and migration in vitro. RESULTS We found that the expression levels of proBDNF, p75NTR, and sortilin were significantly increased in high-grade glioma and were positively correlated with the malignancy of the tumor. We also observed that tumors expressed proBDNF, p75NTR, and sortilin in the same cells with different subcellular distributions, suggesting an autocrine or paracrine loop. The ratio of proBDNF to mature BDNF was decreased in high-grade glioma tissues and was negatively correlated with tumor grade. Using C6 glioma cells as a model, we found that proBDNF increased apoptosis and differentiation and decreased cell growth and migration in vitro via p75NTR. CONCLUSIONS Our data indicate that proBDNF and its receptors are upregulated in high-grade glioma and might play an inhibitory effect on glioma.
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Affiliation(s)
- Jing Xiong
- Key Laboratory of Stem Cells and Regenerative Medicine, Institute of Molecular and Clinical Medicine, Kunming Medical University, Kunming, Yunnan Province, PR China
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76
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Elshaer SL, Abdelsaid MA, Al-Azayzih A, Kumar P, Matragoon S, Nussbaum JJ, El-Remessy AB. Pronerve growth factor induces angiogenesis via activation of TrkA: possible role in proliferative diabetic retinopathy. J Diabetes Res 2013; 2013:432659. [PMID: 23998130 PMCID: PMC3753742 DOI: 10.1155/2013/432659] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 07/04/2013] [Accepted: 07/12/2013] [Indexed: 01/08/2023] Open
Abstract
Proliferative diabetic retinopathy (PDR) is the leading cause of blindness in working age Americans. We demonstrated that diabetes disturbs the homeostasis of nerve growth factor (NGF) resulting in accumulation of its precursor proNGF. Increases in proNGF were positively correlated with progression of diabetic retinopathy, having the highest level in ocular fluids from PDR patients compared to nondiabetic patients. Here, we attempted to evaluate the contribution and the possible mechanism of proNGF to PDR. The angiogenic response of aqueous humor samples from PDR patients was examined in human retinal endothelial cells in the presence or absence of anti-proNGF antibody. Additional cultures were treated with mutant-proNGF in the presence of specific pharmacological inhibitors of TrkA and p75(NTR) receptors. PDR-aqueous humor samples exerted significant angiogenic response including cell proliferation, migration, and alignment into tube-like structures. These effects were significantly reduced by anti-proNGF antibody but not by IgG. Treatment of retinal endothelial cells with mutant-proNGF activated phosphorylation of TrkA and p38MAPK; however, it did not alter p75(NTR) expression. Inhibition of TrkA but not p75(NTR) significantly reduced mutant-proNGF-induced cell proliferation, cell migration, and tube formation. Taken together, these results provide evidence that proNGF can contribute to PDR at least in part via activation of TrkA.
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Affiliation(s)
- Sally L. Elshaer
- Center for Pharmacy and Experimental Therapeutics, University of Georgia, 1120 15th Street HM-1200, Augusta, GA 30912, USA
- Culver Vision Discovery Institute, Georgia Reagents University, Augusta, GA 30912, USA
- Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
| | - Mohammed A. Abdelsaid
- Center for Pharmacy and Experimental Therapeutics, University of Georgia, 1120 15th Street HM-1200, Augusta, GA 30912, USA
- Culver Vision Discovery Institute, Georgia Reagents University, Augusta, GA 30912, USA
- Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
- Department of Physiology, Georgia Reagents University, Augusta, Georgia 30912, USA
| | - Ahmad Al-Azayzih
- Center for Pharmacy and Experimental Therapeutics, University of Georgia, 1120 15th Street HM-1200, Augusta, GA 30912, USA
- Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
| | - Parag Kumar
- Center for Pharmacy and Experimental Therapeutics, University of Georgia, 1120 15th Street HM-1200, Augusta, GA 30912, USA
- Pharmacy Department, National Institutes of Health Clinical Center, Bethesda, MD 20892, USA
| | - Suraporn Matragoon
- Center for Pharmacy and Experimental Therapeutics, University of Georgia, 1120 15th Street HM-1200, Augusta, GA 30912, USA
- Culver Vision Discovery Institute, Georgia Reagents University, Augusta, GA 30912, USA
- Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
| | - Julian J. Nussbaum
- Culver Vision Discovery Institute, Georgia Reagents University, Augusta, GA 30912, USA
| | - Azza B. El-Remessy
- Center for Pharmacy and Experimental Therapeutics, University of Georgia, 1120 15th Street HM-1200, Augusta, GA 30912, USA
- Culver Vision Discovery Institute, Georgia Reagents University, Augusta, GA 30912, USA
- Charlie Norwood VA Medical Center, Augusta, GA 30912, USA
- *Azza B. El-Remessy:
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77
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Sykes AM, Palstra N, Abankwa D, Hill JM, Skeldal S, Matusica D, Venkatraman P, Hancock JF, Coulson EJ. The effects of transmembrane sequence and dimerization on cleavage of the p75 neurotrophin receptor by γ-secretase. J Biol Chem 2012; 287:43810-24. [PMID: 23105112 DOI: 10.1074/jbc.m112.382903] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cleavage of transmembrane receptors by γ-secretase is the final step in the process of regulated intramembrane proteolysis (RIP) and has a significant impact on receptor function. Although relatively little is known about the molecular mechanism of γ-secretase enzymatic activity, it is becoming clear that substrate dimerization and/or the α-helical structure of the substrate can regulate the site and rate of γ-secretase activity. Here we show that the transmembrane domain of the pan-neurotrophin receptor p75(NTR), best known for regulating neuronal death, is sufficient for its homodimerization. Although the p75(NTR) ligands NGF and pro-NGF do not induce homerdimerization or RIP, homodimers of p75(NTR) are γ-secretase substrates. However, dimerization is not a requirement for p75(NTR) cleavage, suggesting that γ-secretase has the ability to recognize and cleave each receptor molecule independently. The transmembrane cysteine 257, which mediates covalent p75(NTR) interactions, is not crucial for homodimerization, but this residue is required for normal rates of γ-secretase cleavage. Similarly, mutation of the residues alanine 262 and glycine 266 of an AXXXG dimerization motif flanking the γ-secretase cleavage site within the p75(NTR) transmembrane domain alters the orientation of the domain and inhibits γ-secretase cleavage of p75(NTR). Nonetheless, heteromer interactions of p75(NTR) with TrkA increase full-length p75(NTR) homodimerization, which in turn potentiates the rate of γ-cleavage following TrkA activation independently of rates of α-cleavage. These results provide support for the idea that the helical structure of the p75(NTR) transmembrane domain, which may be affected by co-receptor interactions, is a key element in γ-secretase-catalyzed cleavage.
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Affiliation(s)
- Alex M Sykes
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
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78
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Skeldal S, Sykes AM, Glerup S, Matusica D, Palstra N, Autio H, Boskovic Z, Madsen P, Castrén E, Nykjaer A, Coulson EJ. Mapping of the interaction site between sortilin and the p75 neurotrophin receptor reveals a regulatory role for the sortilin intracellular domain in p75 neurotrophin receptor shedding and apoptosis. J Biol Chem 2012; 287:43798-809. [PMID: 23105113 DOI: 10.1074/jbc.m112.374710] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neurotrophins comprise a group of neuronal growth factors that are essential for the development and maintenance of the nervous system. However, the immature pro-neurotrophins promote apoptosis by engaging in a complex with sortilin and the p75 neurotrophin receptor (p75(NTR)). To identify the interaction site between sortilin and p75(NTR), we analyzed binding between chimeric receptor constructs and truncated p75(NTR) variants by co-immunoprecipitation experiments, surface plasmon resonance analysis, and FRET. We found that complex formation between sortilin and p75(NTR) relies on contact points in the extracellular domains of the receptors. We also determined that the interaction critically depends on an extracellular juxtamembrane 23-amino acid sequence of p75(NTR). Functional studies further revealed an important regulatory function of the sortilin intracellular domain in p75(NTR)-regulated intramembrane proteolysis and apoptosis. Thus, although the intracellular domain of sortilin does not contribute to p75(NTR) binding, it does regulate the rates of p75(NTR) cleavage, which is required to mediate pro-neurotrophin-stimulated cell death.
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Affiliation(s)
- Sune Skeldal
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
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79
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Abstract
Neuroligin (NLG), a postsynaptic adhesion molecule, is involved in the formation of synapses by binding to a cognate presynaptic ligand, neurexin. Here we report that neuroligin-1 (NLG1) undergoes ectodomain shedding at the juxtamembrane stalk region to generate a secreted form of NLG1 and a membrane-tethered C-terminal fragment (CTF) in adult rat brains in vivo as well as in neuronal cultures. Pharmacological and genetic studies identified ADAM10 as the major protease responsible for NLG1 shedding, the latter being augmented by synaptic NMDA receptor activation or interaction with soluble neurexin ligands. NLG1-CTF was subsequently cleaved by presenilin/γ-secretase. Secretion of soluble NLG1 was significantly upregulated under a prolonged epileptic seizure condition, and inhibition of NLG1 shedding led to an increase in numbers of dendritic spines in neuronal cultures. Collectively, neuronal activity-dependent proteolytic processing of NLG1 may negatively regulate the remodeling of spines at excitatory synapses.
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80
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Green SH, Bailey E, Wang Q, Davis RL. The Trk A, B, C's of Neurotrophins in the Cochlea. Anat Rec (Hoboken) 2012; 295:1877-95. [DOI: 10.1002/ar.22587] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 07/24/2012] [Indexed: 12/20/2022]
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81
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Bessette B, Durand K, Giraud S, Bégaud G, Mathonnet M, Lalloué F. Decrease in Fas-induced apoptosis by the γ-secretase inhibitor is dependent on p75(NTR) in a glioblastoma cell line. Exp Ther Med 2012; 3:873-877. [PMID: 22969985 DOI: 10.3892/etm.2012.480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 01/17/2012] [Indexed: 11/06/2022] Open
Abstract
p75(NTR), a member of the tumor necrosis factor superfamily, plays a key role in numerous physiological processes, including cell survival or apoptosis. Yet, the associated signaling pathways remain poorly understood. Similar to Notch, γ-secretase cleavage is implicated in the p75(NTR) signaling pathway leading to nuclear translocation of the intracellular domain and cell death. Fas receptor activation was found to promote cell death apoptosis in several cell lines. The goal of this study was to determine the respective role of p75(NTR) and Notch in the resistance to Fas-induced apoptosis in the U-87 MG glioblastoma cell line. Using the γ-secretase inhibitor, we investigated the modulation of Fas-induced apoptosis dependent on p75(NTR)-Fas receptor interaction. Whereas the U-87 MG cells expressed the Fas receptor at the cell membrane, apoptosis induced by Fas activation was decreased by the γ-secretase inhibitor. These data suggest that γ-secretase is implicated in p75(NTR) and Fas interaction leading to cell death signaling.
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Affiliation(s)
- Barbara Bessette
- University of Limoges, EA3842, 'Cellular Homeostasis and Pathology', Faculty of Medicine, 87025 Limoges Cedex
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82
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Scarpi D, Cirelli D, Matrone C, Castronovo G, Rosini P, Occhiato EG, Romano F, Bartali L, Clemente AM, Bottegoni G, Cavalli A, De Chiara G, Bonini P, Calissano P, Palamara AT, Garaci E, Torcia MG, Guarna A, Cozzolino F. Low molecular weight, non-peptidic agonists of TrkA receptor with NGF-mimetic activity. Cell Death Dis 2012; 3:e339. [PMID: 22764098 PMCID: PMC3406579 DOI: 10.1038/cddis.2012.80] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Exploitation of the biologic activity of neurotrophins is desirable for medical purposes, but their protein nature intrinsically bears adverse pharmacokinetic properties. Here, we report synthesis and biologic characterization of a novel class of low molecular weight, non-peptidic compounds with NGF (nerve growth factor)-mimetic properties. MT2, a representative compound, bound to Trk (tropomyosin kinase receptor)A chain on NGF-sensitive cells, as well as in cell-free assays, at nanomolar concentrations and induced TrkA autophosphorylation and receptor-mediated internalization. MT2 binding involved at least two amino-acid residues within TrkA molecule. Like NGF, MT2 increased phosphorylation of extracellular signal-regulated kinase1/2 and Akt proteins and production of MKP-1 phosphatase (dual specificity phosphatase 1), modulated p38 mitogen-activated protein kinase activation, sustained survival of serum-starved PC12 or RDG cells, and promoted their differentiation. However, the intensity of such responses was heterogenous, as the ability of maintaining survival was equally possessed by NGF and MT2, whereas the induction of differentiation was expressed at definitely lower levels by the mimetic. Analysis of TrkA autophosphorylation patterns induced by MT2 revealed a strong tyrosine (Tyr)490 and a limited Tyr785 and Tyr674/675 activation, findings coherent with the observed functional divarication. Consistently, in an NGF-deprived rat hippocampal neuronal model of Alzheimer Disease, MT2 could correct the biochemical abnormalities and sustain cell survival. Thus, NGF mimetics may reveal interesting investigational tools in neurobiology, as well as promising drug candidates.
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Affiliation(s)
- D Scarpi
- Department of Chemistry Ugo Schiff, University of Firenze, Firenze, Italy
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83
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Bradshaw JM, Nguyen L, Wallace W, Li C, Sauer JM, Bard F, Bova MP. Monitoring signaling by the p75(NTR) receptor utilizing a caspase-3 activation assay amenable to small-molecule screening. Assay Drug Dev Technol 2012; 10:353-64. [PMID: 22663019 DOI: 10.1089/adt.2011.398] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
p75(NTR) is a neurotrophin receptor that can mediate either survival or death of neurons depending on the cell context. Modulation of p75(NTR) is a promising strategy to promote neuronal survival for treatment of cognitive disorders such as Alzheimer's disease. Despite years of investigation into the signaling mechanisms of p75(NTR), no p75(NTR) signaling assay has yet been developed that is compatible with efficient screening of small-molecule modulators. In this work, we developed a homogeneous cell-based assay for screening p75(NTR) modulators and studying p75(NTR) function. Stimulation of p75(NTR)-transfected cells using either nerve growth factor (NGF) or Pro-NGF resulted in an enhanced caspase-3 activity as assessed by cleavage of a fluorescent caspase-3 substrate. Optimization of the assay with respect to time, cell density, NGF and Pro-NGF concentration, and other factors provided a twofold increase in the caspase-3 activity compared to background. Withdrawal of serum during the NGF or Pro-NGF treatment period was found to be essential for p75(NTR)-dependent caspase-3 activation. We validated the method by demonstrating that a signaling-incompetent p75(NTR) mutant could not substitute for wild-type p75(NTR) in mediating caspase-3 activation. A focused library screen identified new inhibitors of p75(NTR) signaling. This method will be useful for identifying small-molecule modulators of p75(NTR) as well as further characterizing downstream signaling events.
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Affiliation(s)
- J Michael Bradshaw
- Department of Biology, Elan Pharmaceuticals, South San Francisco, California, USA.
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84
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Abstract
The Alzheimer's disease (AD)-associated amyloid-β protein precursor (AβPP) is cleaved by α-, β-, and presenilin (PS)/γ-secretases through sequential regulated proteolysis. These proteolytic events control the generation of the pathogenic amyloid-β (Aβ) peptide, which excessively accumulates in the brains of individuals afflicted by AD. A growing number of additional proteins cleaved by PS/γ-secretase continue to be discovered. Similarly to AβPP, most of these proteins are type-I transmembrane proteins involved in vital signaling functions regulating cell fate, adhesion, migration, neurite outgrowth, or synaptogenesis. All the identified proteins share common structural features, which are typical for their proteolysis. The consequences of the PS/γ-secretase-mediated cleavage on the function of many of these proteins are largely unknown. Here, we review the current literature on the proteolytic processing mediated by the versatile PS/γ-secretase complex. We begin by discussing the steps of AβPP processing and PS/γ-secretase complex composition and localization, which give clues to how and where the processing of other PS/γ-secretase substrates may take place. Then we summarize the typical features of PS/γ-secretase-mediated protein processing. Finally, we recapitulate the current knowledge on the possible physiological function of PS/γ-secretase-mediated cleavage of specific substrate proteins.
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Affiliation(s)
- Annakaisa Haapasalo
- Institute of Clinical Medicine-Neurology, University of Eastern Finland, Kuopio, Finland.
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85
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Nerve growth factor-induced cell cycle reentry in newborn neurons is triggered by p38MAPK-dependent E2F4 phosphorylation. Mol Cell Biol 2012; 32:2722-37. [PMID: 22586272 DOI: 10.1128/mcb.00239-12] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cumulative evidence indicates that activation of cyclin D-dependent kinase 4/6 (cdk4/6) represents a major trigger of cell cycle reentry and apoptosis in vertebrate neurons. We show here the existence of another mechanism triggering cell cycle reentry in differentiating chick retinal neurons (DCRNs), based on phosphorylation of E2F4 by p38(MAPK). We demonstrate that the activation of p75(NTR) by nerve growth factor (NGF) induces nuclear p38(MAPK) kinase activity, which leads to Thr phosphorylation and subsequent recruitment of E2F4 to the E2F-responsive cdc2 promoter. Inhibition of p38(MAPK), but not of cdk4/6, specifically prevents NGF-dependent cell cycle reentry and apoptosis in DCRNs. Moreover, a constitutively active form of chick E2F4 (Thr261Glu/Thr263Glu) stimulates G(1)/S transition and apoptosis, even after inhibition of p38(MAPK) activity. In contrast, a dominant-negative E2F4 form (Thr261Ala/Thr263Ala) prevents NGF-induced cell cycle reactivation and cell death in DCRNs. These results indicate that NGF-induced cell cycle reentry in neurons depends on the activation of a novel, cdk4/6-independent pathway that may participate in neurodegeneration.
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86
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Sun Y, Lim Y, Li F, Liu S, Lu JJ, Haberberger R, Zhong JH, Zhou XF. ProBDNF collapses neurite outgrowth of primary neurons by activating RhoA. PLoS One 2012; 7:e35883. [PMID: 22558255 PMCID: PMC3338794 DOI: 10.1371/journal.pone.0035883] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 03/23/2012] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Neurons extend their dendrites and axons to build functional neural circuits, which are regulated by both positive and negative signals during development. Brain-derived neurotrophic factor (BDNF) is a positive regulator for neurite outgrowth and neuronal survival but the functions of its precursor (proBDNF) are less characterized. METHODOLOGY/PRINCIPAL FINDINGS Here we show that proBDNF collapses neurite outgrowth in murine dorsal root ganglion (DRG) neurons and cortical neurons by activating RhoA via the p75 neurotrophin receptor (p75NTR). We demonstrated that the receptor proteins for proBDNF, p75NTR and sortilin, were highly expressed in cultured DRG or cortical neurons. ProBDNF caused a dramatic neurite collapse in a dose-dependent manner and this effect was about 500 fold more potent than myelin-associated glycoprotein. Neutralization of endogenous proBDNF by using antibodies enhanced neurite outgrowth in vitro and in vivo, but this effect was lost in p75NTR(-/-) mice. The neurite outgrowth of cortical neurons from p75NTR deficient (p75NTR(-/-)) mice was insensitive to proBDNF. There was a time-dependent reduction of length and number of filopodia in response to proBDNF which was accompanied with a polarized RhoA activation in growth cones. Moreover, proBDNF treatment of cortical neurons resulted in a time-dependent activation of RhoA but not Cdc42 and the effect was absent in p75NTR(-/-) neurons. Rho kinase (ROCK) and the collapsin response mediator protein-2 (CRMP-2) were also involved in the proBDNF action. CONCLUSIONS proBDNF has an opposing role in neurite outgrowth to that of mature BDNF. Our observations suggest that proBDNF collapses neurites outgrowth and filopodial growth cones by activating RhoA through the p75NTR signaling pathway.
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MESH Headings
- Adaptor Proteins, Vesicular Transport/genetics
- Adaptor Proteins, Vesicular Transport/metabolism
- Animals
- Antibodies/pharmacology
- Brain-Derived Neurotrophic Factor/antagonists & inhibitors
- Brain-Derived Neurotrophic Factor/pharmacology
- Brain-Derived Neurotrophic Factor/physiology
- Cells, Cultured
- Ganglia, Spinal/cytology
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/physiology
- Gene Expression Regulation, Developmental/physiology
- Mice
- Mice, Knockout
- Nerve Fibers/drug effects
- Nerve Fibers/physiology
- Neurites/drug effects
- Neurites/physiology
- Protein Precursors/pharmacology
- Protein Precursors/physiology
- Pseudopodia/drug effects
- Pseudopodia/physiology
- Receptors, Nerve Growth Factor/deficiency
- Receptors, Nerve Growth Factor/genetics
- Signal Transduction/physiology
- Time-Lapse Imaging
- rho GTP-Binding Proteins/agonists
- rho GTP-Binding Proteins/genetics
- rho GTP-Binding Proteins/metabolism
- rhoA GTP-Binding Protein
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Affiliation(s)
- Ying Sun
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, Australia
| | - Yoon Lim
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, Australia
- Division of Health Science, Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia
| | - Fang Li
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, Australia
| | - Shen Liu
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, Australia
- Division of Health Science, Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia
| | - Jian-Jun Lu
- Division of Health Science, Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia
| | - Rainer Haberberger
- Department of Anatomy and Histology and Centre for Neuroscience, Flinders University, Adelaide, Australia
| | - Jin-Hua Zhong
- Division of Health Science, Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia
| | - Xin-Fu Zhou
- Division of Health Science, Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia
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87
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Nykjaer A, Willnow TE. Sortilin: a receptor to regulate neuronal viability and function. Trends Neurosci 2012; 35:261-70. [DOI: 10.1016/j.tins.2012.01.003] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 01/08/2012] [Accepted: 01/10/2012] [Indexed: 11/26/2022]
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88
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Ichim G, Tauszig-Delamasure S, Mehlen P. Neurotrophins and cell death. Exp Cell Res 2012; 318:1221-8. [PMID: 22465479 DOI: 10.1016/j.yexcr.2012.03.006] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 03/07/2012] [Accepted: 03/10/2012] [Indexed: 11/18/2022]
Abstract
The neurotrophins - NGF, BDNF, NT-3 - are secreted proteins that play a major role in neuron survival, differentiation and axon wiring toward target territories. They do so by interacting with their main tyrosine kinase receptors TrkA, TrkB, TrkC and p75(NTR). Even though there is a general consensus on the view that neurotrophins are survival factors, there are two fundamentally different views on how they achieve this survival activity. One prevailing view is that all neurons and more generally all normal cells are naturally committed to die unless a survival factor blocks this death. This death results from the engagement of a "default" apoptotic cell program. The minority report supports, on the opposite, that neurotrophin withdrawal is associated with an active signal of cell death induced by unbound dependence receptors. We will discuss here how neurotrophins regulate cell death and survival and how this has implications not only during nervous system development but also during cancer progression.
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Affiliation(s)
- Gabriel Ichim
- Apoptosis, Cancer and Development Laboratory, Equipe labellisée La Ligue, Centre de Recherche en Cancérologie de Lyon, INSERM U1052-CNRS UMR5286, Université de Lyon, Centre Léon Bérard, Lyon, France
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89
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He B, Bao G, Guo S, Xu G, Li Q, Wang N. Association between p75 neurotrophin receptor gene expression and cell apoptosis in tissues surrounding hematomas in rat models of intracerebral hemorrhage. Neural Regen Res 2012; 7:589-94. [PMID: 25745449 PMCID: PMC4346983 DOI: 10.3969/j.issn.1673-5374.2012.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 02/08/2012] [Indexed: 01/06/2023] Open
Abstract
Animal models of intracerebral hemorrhage were established by injection of autologous blood into the caudate nucleus in rats. Cell apoptosis was measured by flow cytometry and immunohistochemical staining of the p75 neurotrophin receptor. p75 neurotrophin receptor protein was detected by immunohistochemistry. p75 neurotrophin receptor mRNA was examined by quantitative real-time polymerase chain reactions. At 24 hours after modeling, cellular apoptosis occured around hematoma with upregulation of p75 neurotrophin receptor protein and mRNA was observed, which directly correlated to apoptosis. This observation indicated that p75 neurotrophin receptor upregulation was associated with cell apoptosis around hematomas after intracerebral hemorrhage.
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Affiliation(s)
- Baixiang He
- Department of Neurosurgery, First Affiliated Hospital of Medical School, Xi’an Jiaotong University, Xi’an 710061, Shaanxi Province, China
| | - Gang Bao
- Department of Neurosurgery, First Affiliated Hospital of Medical School, Xi’an Jiaotong University, Xi’an 710061, Shaanxi Province, China
| | - Shiwen Guo
- Department of Neurosurgery, First Affiliated Hospital of Medical School, Xi’an Jiaotong University, Xi’an 710061, Shaanxi Province, China
| | - Gaofeng Xu
- Department of Neurosurgery, First Affiliated Hospital of Medical School, Xi’an Jiaotong University, Xi’an 710061, Shaanxi Province, China
| | - Qi Li
- Department of Neurosurgery, First Affiliated Hospital of Medical School, Xi’an Jiaotong University, Xi’an 710061, Shaanxi Province, China
| | - Ning Wang
- Department of Neurosurgery, First Affiliated Hospital of Medical School, Xi’an Jiaotong University, Xi’an 710061, Shaanxi Province, China
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90
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Allen SJ, Watson JJ, Dawbarn D. The neurotrophins and their role in Alzheimer's disease. Curr Neuropharmacol 2011; 9:559-73. [PMID: 22654716 PMCID: PMC3263452 DOI: 10.2174/157015911798376190] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 08/19/2010] [Accepted: 08/19/2010] [Indexed: 12/15/2022] Open
Abstract
Besides being essential for correct development of the vertebrate nervous system the neurotrophins also play a vital role in adult neuron survival, maintenance and regeneration. In addition they are implicated in the pathogenesis of certain neurodegenerative diseases, and may even provide a therapeutic solution for some. In particular there have been a number of studies on the involvement of nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) in the development of Alzheimer's disease. This disease is of growing concern as longevity increases worldwide, with little treatment available at the moment to alleviate the condition. Memory loss is one of the earliest symptoms associated with Alzheimer's disease. The brain regions first affected by pathology include the hippocampus, and also the entorhinal cortex and basal cholinergic nuclei which project to the hippocampus; importantly, all these areas are required for memory formation. Both NGF and BDNF are affected early in the disease and this is thought to initiate a cascade of events which exacerbates pathology and leads to the symptoms of dementia. This review briefly describes the pathology, symptoms and molecular processes associated with Alzheimer's disease; it discusses the involvement of the neurotrophins, particularly NGF and BDNF, and their receptors, with changes in BDNF considered particularly in the light of its importance in synaptic plasticity. In addition, the possibilities of neurotrophin-based therapeutics are evaluated.
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Affiliation(s)
- Shelley J Allen
- Dorothy Hodgkin Building, School of Clinical Sciences, University of Bristol, Bristol BS1 3NY, UK
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91
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Le Moan N, Houslay DM, Christian F, Houslay MD, Akassoglou K. Oxygen-dependent cleavage of the p75 neurotrophin receptor triggers stabilization of HIF-1α. Mol Cell 2011; 44:476-90. [PMID: 22055192 PMCID: PMC3212815 DOI: 10.1016/j.molcel.2011.08.033] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 05/23/2011] [Accepted: 08/15/2011] [Indexed: 12/23/2022]
Abstract
Homeostatic control of oxygen availability allows cells to survive oxygen deprivation. Although the transcription factor hypoxia-inducible factor 1α (HIF-1α) is the main regulator of the hypoxic response, the upstream mechanisms required for its stabilization remain elusive. Here, we show that p75 neurotrophin receptor (p75(NTR)) undergoes hypoxia-induced γ-secretase-dependent cleavage to provide a positive feed-forward mechanism required for oxygen-dependent HIF-1α stabilization. The intracellular domain of p75(NTR) directly interacts with the evolutionarily conserved zinc finger domains of the E3 RING ubiquitin ligase Siah2 (seven in absentia homolog 2), which regulates HIF-1α degradation. p75(NTR) stabilizes Siah2 by decreasing its auto-ubiquitination. Genetic loss of p75(NTR) dramatically decreases Siah2 abundance, HIF-1α stabilization, and induction of HIF-1α target genes in hypoxia. p75(NTR-/-) mice show reduced HIF-1α stabilization, vascular endothelial growth factor (VEGF) expression, and neoangiogenesis after retinal hypoxia. Thus, hypoxia-induced intramembrane proteolysis of p75(NTR) constitutes an apical oxygen-dependent mechanism to control the magnitude of the hypoxic response.
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Affiliation(s)
- Natacha Le Moan
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Daniel M. Houslay
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Frank Christian
- Molecular Pharmacology Group, Biochemistry & Molecular Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Miles D. Houslay
- Molecular Pharmacology Group, Biochemistry & Molecular Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Katerina Akassoglou
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
- Department of Neurology, University of California, San Francisco, CA 94158, USA
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92
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Evans SF, Irmady K, Ostrow K, Kim T, Nykjaer A, Saftig P, Blobel C, Hempstead BL. Neuronal brain-derived neurotrophic factor is synthesized in excess, with levels regulated by sortilin-mediated trafficking and lysosomal degradation. J Biol Chem 2011; 286:29556-67. [PMID: 21730062 DOI: 10.1074/jbc.m111.219675] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) regulates neuronal differentiation, synaptic plasticity, and morphology, and modest changes in BDNF levels results in complex behavioral phenotypes. BDNF levels and intracellular localization in neurons are regulated by multiple mechanisms, including use of distinct promoters, mRNA and protein transport, and regulated cleavage of proBDNF to mature BDNF. Sortilin is an intracellular chaperone that binds to the prodomain of BDNF to traffic it to the regulated secretory pathway. However, sortilin binds to numerous ligands and plays a major role in mannose 6-phosphate receptor-independent transport of lysosomal hydrolases utilizing motifs in the intracellular domain that mediate trafficking from the Golgi and late endosomes. Sortilin is modified by ectodomain shedding, although the biological implications of this are not known. Here we demonstrate that ADAM10 is the preferred protease to cleave sortilin in the extracellular stalk region, to release the ligand binding sortilin ectodomain from the transmembrane and cytoplasmic domains. We identify sortilin shedding at the cell surface and in an intracellular compartment. Both sortilin and BDNF are trafficked to and degraded by the lysosome in neurons, and this is dependent upon the sortilin cytoplasmic tail. Indeed, expression of the sortilin ectodomain, which corresponds to the domain released after shedding, impairs lysosomal targeting and degradation of BDNF. These findings characterize the regulation of sortilin shedding and identify a novel mechanism by which sortilin ectodomain shedding acts as a regulatory switch for delivery of BDNF to the secretory pathway or to the lysosome, thus modulating the bioavailability of endogenous BDNF.
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Affiliation(s)
- Sarah Felice Evans
- Graduate Program in Neuroscience, Weill Medical College of Cornell University, New York, New York 10065, USA
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93
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Skeldal S, Matusica D, Nykjaer A, Coulson EJ. Proteolytic processing of the p75 neurotrophin receptor: A prerequisite for signalling?: Neuronal life, growth and death signalling are crucially regulated by intra-membrane proteolysis and trafficking of p75(NTR). Bioessays 2011; 33:614-25. [PMID: 21717487 DOI: 10.1002/bies.201100036] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The common neurotrophin receptor (p75(NTR) ) regulates various functions in the developing and adult nervous system. Cell survival, cell death, axonal and growth cone retraction, and regulation of the cell cycle can be regulated by p75(NTR) -mediated signals following activation by either mature or pro-neurotrophins and in combination with various co-receptors, including Trk receptors and sortilin. Here, we review the known functions of p75(NTR) by cell type, receptor-ligand combination, and whether regulated intra-membrane proteolysis of p75(NTR) is required for signalling. We highlight that the generation of the intracellular domain fragment of p75(NTR) is associated with many of the receptor functions, regardless of its ligand and co-receptor interactions.
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Affiliation(s)
- Sune Skeldal
- The Lundbeck Foundation Research Center MIND, Department of Medical Biochemistry, Aarhus University, Aarhus, Denmark.
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94
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Spuch C, Carro E. The p75 neurotrophin receptor localization in blood-CSF barrier: expression in choroid plexus epithelium. BMC Neurosci 2011; 12:39. [PMID: 21569322 PMCID: PMC3103472 DOI: 10.1186/1471-2202-12-39] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 05/11/2011] [Indexed: 02/11/2023] Open
Abstract
BACKGROUND The presence of neurotrophins and their receptors Trk family has been reported in the choroid plexus. High levels of Nerve Growth Factor (NGF), Neurotrophin-4 (NT-4) and TrkB receptor were detected, while nothing was know about p75 neurotrophin receptor (p75NTR) in the choroid plexus epithelial cells. In neurons, p75NTR receptor has a dual function: promoting survival together with TrkA in response to NGF, and inducing apoptotic signaling through p75NTR. We postulated that p75NTR may also affect the survival pathways in the choroid plexus and also undergoes regulated proteolysis with metalloproteases. RESULTS Here, we demonstrated the presence of p75NTR receptor in the choroid plexus epithelial cells. The p75NTR receptor would be involved in cell death mechanisms and in the damaged induced by amyloid beta (Aβ) in the choroid plexus and finally, we propose an essential role of p75NTR in the Aβ transcytosis through out choroid plexus barrier. CONCLUSIONS The presence analysis reveals the new localization of p75NTR in the choroid plexus and, the distribution mainly in the cytoplasm and cerebrospinal fluid (CSF) side of the epithelial cells. We propose that p75NTR receptor plays a role in the survival pathways and Aβ-induced cell death. These data suggest that p75NTR dysfunction play an important role in the pathogenesis of brain diseases. The importance and novelty of this expression expands a new role of p75NTR.
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Affiliation(s)
- Carlos Spuch
- Neuroscience Group, Research Institute Hospital 12 de Octubre, Madrid, Spain.
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95
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Kommaddi RP, Thomas R, Ceni C, Daigneault K, Barker PA. Trk-dependent ADAM17 activation facilitates neurotrophin survival signaling. FASEB J 2011; 25:2061-70. [PMID: 21411748 DOI: 10.1096/fj.10-173740] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Signaling by TrkA and TrkB receptor tyrosine kinase is required for peripheral neuron survival. TrkA and TrkB signaling is facilitated by the p75 neurotrophin receptor (p75NTR), a member of the tumor necrosis factor (TNF) receptor superfamily, through mechanisms that remain obscure. Here, we demonstrate that TrkA and TrkB induces MEK-dependent phosphorylation of the transmembrane cysteine protease ADAM17 (a disintegrin and metalloprotease 17) at the intracellular residue threonine 735. Phosphorylation at this site activates ADAM17 and causes cleavage of p75NTR and production of the receptors' intracellular domain (p75NTR(ICD)) in PC12 cells and in primary cerebellar granule neurons. We show that Trk-induced ADAM17 phosphorylation and generation of the p75NTR(ICD) is required for neurotrophin-induced Erk and Akt activation and for neurotrophin-dependent survival signaling. Survival of PC12 cells maintained in 10 ng/ml nerve growth factor drops by 47% in cells depleted of ADAM17; this survival deficit is resolved if the p75NTR(ICD) is overexpressed in the ADAM17 depleted cells. These studies identify a novel signaling circuit in which Trk activates ADAM17-dependent p75NTR(ICD) production to feedback to sustain Trk signaling and Trk-dependent survival.
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Affiliation(s)
- Reddy P Kommaddi
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University St., Montreal, QC, Canada, H3A 2B4
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96
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Xu ZQ, Sun Y, Li HY, Lim Y, Zhong JH, Zhou XF. Endogenous proBDNF is a negative regulator of migration of cerebellar granule cells in neonatal mice. Eur J Neurosci 2011; 33:1376-84. [DOI: 10.1111/j.1460-9568.2011.07635.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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97
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Astuti D, Ricketts CJ, Chowdhury R, McDonough MA, Gentle D, Kirby G, Schlisio S, Kenchappa RS, Carter BD, Kaelin WG, Ratcliffe PJ, Schofield CJ, Latif F, Maher ER. Mutation analysis of HIF prolyl hydroxylases (PHD/EGLN) in individuals with features of phaeochromocytoma and renal cell carcinoma susceptibility. Endocr Relat Cancer 2011; 18:73-83. [PMID: 20959442 PMCID: PMC3006001 DOI: 10.1677/erc-10-0113] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Germline mutations in the von Hippel-Lindau disease (VHL) and succinate dehydrogenase subunit B (SDHB) genes can cause inherited phaeochromocytoma and/or renal cell carcinoma (RCC). Dysregulation of the hypoxia-inducible factor (HIF) transcription factors has been linked to VHL and SDHB-related RCC; both HIF dysregulation and disordered function of a prolyl hydroxylase domain isoform 3 (PHD3/EGLN3)-related pathway of neuronal apoptosis have been linked to the development of phaeochromocytoma. The 2-oxoglutarate-dependent prolyl hydroxylase enzymes PHD1 (EGLN2), PHD2 (EGLN1) and PHD3 (EGLN3) have a key role in regulating the stability of HIF-α subunits (and hence expression of the HIF-α transcription factors). A germline PHD2 mutation has been reported in association with congenital erythrocytosis and recurrent extra-adrenal phaeochromocytoma. We undertook mutation analysis of PHD1, PHD2 and PHD3 in two cohorts of patients with features of inherited phaeochromocytoma (n=82) and inherited RCC (n=64) and no evidence of germline mutations in known susceptibility genes. No confirmed pathogenic mutations were detected suggesting that mutations in these genes are not a frequent cause of inherited phaeochromocytoma or RCC.
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Affiliation(s)
- Dewi Astuti
- Centre for Rare Diseases and Personalised MedicineUniversity of BirminghamBirmingham, B15 2TTUK
- CRUK Renal Molecular Oncology Group, Medical and Molecular GeneticsSchool of Clinical and Experimental Medicine, Institute of Biomedical Research, University of Birmingham College of Medical and Dental SciencesBirmingham, B15 2TTUK
| | - Christopher J Ricketts
- Centre for Rare Diseases and Personalised MedicineUniversity of BirminghamBirmingham, B15 2TTUK
- CRUK Renal Molecular Oncology Group, Medical and Molecular GeneticsSchool of Clinical and Experimental Medicine, Institute of Biomedical Research, University of Birmingham College of Medical and Dental SciencesBirmingham, B15 2TTUK
| | - Rasheduzzaman Chowdhury
- Chemistry Research Laboratory, Department of ChemistryUniversity of OxfordMansfield Road, Oxford, OX1 3TAUK
| | - Michael A McDonough
- Chemistry Research Laboratory, Department of ChemistryUniversity of OxfordMansfield Road, Oxford, OX1 3TAUK
| | - Dean Gentle
- Centre for Rare Diseases and Personalised MedicineUniversity of BirminghamBirmingham, B15 2TTUK
- CRUK Renal Molecular Oncology Group, Medical and Molecular GeneticsSchool of Clinical and Experimental Medicine, Institute of Biomedical Research, University of Birmingham College of Medical and Dental SciencesBirmingham, B15 2TTUK
| | - Gail Kirby
- Centre for Rare Diseases and Personalised MedicineUniversity of BirminghamBirmingham, B15 2TTUK
- CRUK Renal Molecular Oncology Group, Medical and Molecular GeneticsSchool of Clinical and Experimental Medicine, Institute of Biomedical Research, University of Birmingham College of Medical and Dental SciencesBirmingham, B15 2TTUK
| | - Susanne Schlisio
- Howard Hughes Medical InstituteDana-Farber Cancer Institute and Brigham and Women's Hospital44 Binney Street, Boston, Massachusetts, 02115USA
- Oxygen Sensing and Cancer LaboratoryLudwig Institute for Cancer Research Ltd, Karolinska InstituteNobelsvag 3, SE-171 77, StockholmSweden
| | - Rajappa S Kenchappa
- Department of Biochemistry and Center for Molecular NeuroscienceVanderbilt University Medical SchoolNashville, Tennessee, 37232USA
| | - Bruce D Carter
- Department of Biochemistry and Center for Molecular NeuroscienceVanderbilt University Medical SchoolNashville, Tennessee, 37232USA
| | - William G Kaelin
- Howard Hughes Medical InstituteDana-Farber Cancer Institute and Brigham and Women's Hospital44 Binney Street, Boston, Massachusetts, 02115USA
| | - Peter J Ratcliffe
- Henry Wellcome Building for Molecular PhysiologyUniversity of OxfordOxford, OX3 9DUUK
| | - Christopher J Schofield
- Chemistry Research Laboratory, Department of ChemistryUniversity of OxfordMansfield Road, Oxford, OX1 3TAUK
| | - Farida Latif
- Centre for Rare Diseases and Personalised MedicineUniversity of BirminghamBirmingham, B15 2TTUK
- CRUK Renal Molecular Oncology Group, Medical and Molecular GeneticsSchool of Clinical and Experimental Medicine, Institute of Biomedical Research, University of Birmingham College of Medical and Dental SciencesBirmingham, B15 2TTUK
| | - Eamonn R Maher
- Centre for Rare Diseases and Personalised MedicineUniversity of BirminghamBirmingham, B15 2TTUK
- CRUK Renal Molecular Oncology Group, Medical and Molecular GeneticsSchool of Clinical and Experimental Medicine, Institute of Biomedical Research, University of Birmingham College of Medical and Dental SciencesBirmingham, B15 2TTUK
- West Midlands Regional Genetics ServiceBirmingham Women's Hospital, EdgbastonBirmingham, B15 2TGUK
- (Correspondence should be addressed to E R Maher, Centre for Rare Diseases and Personalised Medicine, Institute of Biomedical Research, University of Birmingham School of Medicine, Birmingham B15 2TT, UK; )
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98
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Bot N, Schweizer C, Ben Halima S, Fraering PC. Processing of the synaptic cell adhesion molecule neurexin-3beta by Alzheimer disease alpha- and gamma-secretases. J Biol Chem 2010; 286:2762-73. [PMID: 21084300 DOI: 10.1074/jbc.m110.142521] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Neurexins (NRXNs) are synaptic cell adhesion molecules having essential roles in the assembly and maturation of synapses into fully functional units. Immunocytochemical and electrophysiological studies have shown that specific binding across the synaptic cleft of the ectodomains of presynaptic NRXNs and postsynaptic neuroligins have the potential to bidirectionally coordinate and trigger synapse formation. Moreover, in vivo studies as well as genome-wide association studies pointed out implication of NRXNs in the pathogenesis of cognitive disorders including autism spectrum disorders and different types of addictions including opioid and alcohol dependences, suggesting an important role in synaptic function. Despite extensive investigations, the mechanisms by which NRXNs modulate the properties of synapses remain largely unknown. We report here that α- and γ-secretases can sequentially process NRXN3β, leading to the formation of two final products, an ∼80-kDa N-terminal extracellular domain of Neurexin-3β (sNRXN3β) and an ∼12-kDa C-terminal intracellular NRXN3β domain (NRXN3β-ICD), both of them being potentially implicated in the regulation of NRXNs and neuroligins functions at the synapses or in yet unidentified signal transduction pathways. We further report that this processing is altered by several PS1 mutations in the catalytic subunit of the γ-secretase that cause early-onset familial Alzheimer disease.
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Affiliation(s)
- Nathalie Bot
- Laboratory of Molecular and Cellular Biology of Alzheimer Disease, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland
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99
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Griesmaier E, Schlager G, Wegleiter K, Hermann M, Urbanek M, Simbruner G, Keller M. Role of p75NTR in NMDAR-mediated excitotoxic brain injury in neonatal mice. Brain Res 2010; 1355:31-40. [PMID: 20692240 DOI: 10.1016/j.brainres.2010.07.095] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2010] [Revised: 07/21/2010] [Accepted: 07/27/2010] [Indexed: 11/30/2022]
Abstract
BACKGROUND Perinatal brain injury in preterm infants is a major cause of neurological handicap. The role of the neurotrophin receptor p75 (p75(NTR)) in the pathogenesis and repair of neonatal excitotoxic brain injury is unknown. Depending on a complex interplay of neurotrophin signalling, p75(NTR) can, in addition to its trophic function, also induce apoptosis. HYPOTHESIS We hypothesised that excitotoxicity increases p75(NTR) expression and p75(NTR) knockout (KO) mice have a significantly smaller lesion size upon excitotoxicity as compared to wild-type (WT) mice. METHODS We used an established animal model of neonatal excitotoxic brain injury mimicking several key aspects of human preterm brain damage. We subjected five-day-old WT and KO mice to excitotoxic injury by means of a single intracranial ibotenate injection (N-methyl-D-aspartate receptor agonist, NMDAR) into one brain hemisphere. Lesion size, number of activated caspase-3- and apoptosis-inducing factor (AIF)-positive cells were determined as outcome parameters. Gender analyses were taken into account retrospectively. RESULTS NMDAR-mediated excitotoxicity induced an upregulation of p75(NTR) expression in the peri-lesion area. Lesion size was significantly increased in female KO as compared to male KO animals. Knockout of p75(NTR) reduced the number of activated caspase-3 but not AIF-positive cells after NMDAR-mediated excitotoxic injury independently of gender. CONCLUSION Since NMDAR-mediated excitotoxic brain injury induced p75(NTR) expression and caspase-3-activated apoptosis in p75(NTR) KO animals was decreased, we conclude that activation of p75(NTR) contributes to NMDAR-mediated apoptosis in the neonatal brain. An increase in lesion size in female animals after excitotoxic brain injury suggests that in females p75(NTR) seems to play a dual role.
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MESH Headings
- Animals
- Animals, Newborn
- Apoptosis/drug effects
- Apoptosis/physiology
- Brain Injury, Chronic/chemically induced
- Brain Injury, Chronic/metabolism
- Brain Injury, Chronic/pathology
- Disease Models, Animal
- Female
- Male
- Mice
- Mice, Knockout
- Neurotoxins/toxicity
- Receptors, N-Methyl-D-Aspartate/drug effects
- Receptors, N-Methyl-D-Aspartate/metabolism
- Receptors, Nerve Growth Factor/genetics
- Receptors, Nerve Growth Factor/physiology
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Affiliation(s)
- Elke Griesmaier
- Department of Paediatrics IV, Neonatology, Neuropaediatrics and Metabolic Diseases, Innsbruck Medical University, Anichstrasse 35, 6020 Innsbruck, Austria.
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100
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Neurotrophin receptors TrkA and TrkC cause neuronal death whereas TrkB does not. Nature 2010; 467:59-63. [PMID: 20811452 DOI: 10.1038/nature09336] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 07/06/2010] [Indexed: 11/08/2022]
Abstract
Neurons of the peripheral nervous system have long been known to require survival factors to prevent their death during development. But why they selectively become dependent on secretory molecules has remained a mystery, as is the observation that in the central nervous system, most neurons do not show this dependency. Using engineered embryonic stem cells, we show here that the neurotrophin receptors TrkA and TrkC (tropomyosin receptor kinase A and C, also known as Ntrk1 and Ntrk3, respectively) instruct developing neurons to die, both in vitro and in vivo. By contrast, TrkB (also known as Ntrk2), a closely related receptor primarily expressed in the central nervous system, does not. These results indicate that TrkA and TrkC behave as dependence receptors, explaining why developing sympathetic and sensory neurons become trophic-factor-dependent for survival. We suggest that the expansion of the Trk gene family that accompanied the segregation of the peripheral from the central nervous system generated a novel mechanism of cell number control.
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