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Danelon V, Garret-Thomson SC, Almo SC, Lee FS, Hempstead BL. Immune activation of the p75 neurotrophin receptor: implications in neuroinflammation. Front Mol Neurosci 2023; 16:1305574. [PMID: 38106879 PMCID: PMC10722190 DOI: 10.3389/fnmol.2023.1305574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 11/10/2023] [Indexed: 12/19/2023] Open
Abstract
Despite structural similarity with other tumor necrosis factor receptor superfamily (TNFRSF) members, the p75 neurotrophin receptor (p75NTR, TNFR16) mediates pleiotropic biological functions not shared with other TNFRs. The high level of p75NTR expression in the nervous system instead of immune cells, its utilization of co-receptors, and its interaction with soluble dimeric, rather than soluble or cell-tethered trimeric ligands are all characteristics which distinguish it from most other TNFRs. Here, we compare these attributes to other members of the TNFR superfamily. In addition, we describe the recent evolutionary adaptation in B7-1 (CD80), an immunoglobulin (Ig) superfamily member, which allows engagement to neuronally-expressed p75NTR. B7-1-mediated binding to p75NTR occurs in humans and other primates, but not lower mammals due to specific sequence changes that evolved recently in primate B7-1. This discovery highlights an additional mechanism by which p75NTR can respond to inflammatory cues and trigger synaptic elimination in the brain through engagement of B7-1, which was considered to be immune-restricted. These observations suggest p75NTR does share commonality with other immune co-modulatory TNFR family members, by responding to immunoregulatory cues. The evolution of primate B7-1 to bind and elicit p75NTR-mediated effects on neuronal morphology and function are discussed in relationship to immune-driven modulation of synaptic actions during injury or inflammation.
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Affiliation(s)
- Victor Danelon
- Department of Medicine, Weill Cornell Graduate School of Medical Sciences, Weill Cornell Medicine, New York, NY, United States
| | | | - Steven C. Almo
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Francis S. Lee
- Department of Psychiatry, Weill Cornell Medicine, New York, NY, United States
| | - Barbara L. Hempstead
- Department of Medicine, Weill Cornell Graduate School of Medical Sciences, Weill Cornell Medicine, New York, NY, United States
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2
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Khatmi A, Eskandarian Boroujeni M, Ezi S, Hamidreza Mirbehbahani S, Aghajanpour F, Soltani R, Hossein Meftahi G, Abdollahifar MA, Hassani Moghaddam M, Toreyhi H, Khodagholi F, Aliaghaei A. Combined molecular, structural and memory data unravel the destructive effect of tramadol on hippocampus. Neurosci Lett 2021; 771:136418. [PMID: 34954113 DOI: 10.1016/j.neulet.2021.136418] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 12/20/2021] [Accepted: 12/20/2021] [Indexed: 11/28/2022]
Abstract
Tramadol is a synthetic analogue of codeine and stimulates neurodegeneration in several parts of the brain that leads to various behavioral impairments. Despite the leading role of hippocampus in learning and memory as well as decreased function of them under influence of tramadol, there are few studies analyzing the effect of tramadol administration on gene expression profiling and structural consequences in hippocampus region. Thus, we sought to determine the effect of tramadol on both PC12 cell line and hippocampal tissue, from gene expression changes to structural alterations. In this respect, we investigated genome-wide mRNA expression using high throughput RNA-seq technology and confirmatory quantitative real-time PCR, accompanied by stereological analysis of hippocampus and behavioral assessment following tramadol exposure. At the cellular level, PC12 cells were exposed to 600μM tramadol for 48 hrs, followed by the assessments of ROS amount and gene expression levels of neurotoxicity associated with neurodegenerative pathways such as apoptosis and autophagy. Moreover, the structural and functional alteration of the hippocampus under chronic exposure to tramadol was also evaluated. In this regard, rats were treated with tramadol at doses of 50 mg/kg for three consecutive weeks. In vitro data revealed that tramadol provoked ROS production and caused the increase in the expression of autophagic and apoptotic genes in PC12 cells. Furthermore, in-vivo results demonstrated that tramadol not only did induce hippocampal atrophy, but it also triggered microgliosis and microglial activation, causing upregulation of apoptotic and inflammatory markers as well as over-activation of neurodegeneration. Tramadol also interrupted spatial learning and memory function along with long-term potentiation (LTP). Taken all together, our data disclosed the neurotoxic effects of tramadol on both in vitro and in-vivo. Moreover, we proposed a potential correlation between disrupted biochemical cascades and memory deficit under tramadol administration.
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Affiliation(s)
- Aysan Khatmi
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Cell Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mahdi Eskandarian Boroujeni
- Department of Human Molecular Genetics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Samira Ezi
- Department of Anatomy, Faculty of Medicine, Gonabad University of Medical Sciences, Gonabad, Iran
| | | | - Fakhroddin Aghajanpour
- Department of Cell Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Reza Soltani
- Department of Cell Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Mohammad-Amin Abdollahifar
- Department of Cell Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Meysam Hassani Moghaddam
- Department of Anatomical Sciences, Faculty of Medicine, AJA University of Medical Sciences, Tehran, Iran
| | - Hossein Toreyhi
- Department of Cell Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fariba Khodagholi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Abbas Aliaghaei
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Cell Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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3
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Tramadol: a Potential Neurotoxic Agent Affecting Prefrontal Cortices in Adult Male Rats and PC-12 Cell Line. Neurotox Res 2020; 38:385-397. [PMID: 32378056 DOI: 10.1007/s12640-020-00214-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 04/19/2020] [Accepted: 04/22/2020] [Indexed: 12/25/2022]
Abstract
Tramadol is a synthetic analogue of codeine that is often prescribed for the treatment of mild to moderate pains. It has a number of side effects including emotional instability and anxiety. In this study, we focus on the structural and functional changes of prefrontal cortex under chronic exposure to tramadol. At the cellular level, the amounts of ROS and annexin V in PC12 cells were evidently increased upon exposure to tramadol (at a concentration of 600 μM for 48 h). To this end, the rats were daily treated with tramadol at doses of 50 mg/kg for 3 weeks. Our findings reveal that tramadol provokes atrophy and apoptosis by the induction of apoptotic markers such as Caspase 3 and 8, pro-inflammatory markers, and downregulation of GDNF. Moreover, it triggers microgliosis and astrogliosis along with neuronal death in the prefrontal cortex. Behavioral disturbance and cognitive impairment are other side effects of tramadol. Overall, our results indicate tramadol-induced neurodegeneration in the prefrontal cortex mainly through activation of neuroinflammatory response.
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4
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Grayfer L, Kerimoglu B, Yaparla A, Hodgkinson JW, Xie J, Belosevic M. Mechanisms of Fish Macrophage Antimicrobial Immunity. Front Immunol 2018; 9:1105. [PMID: 29892285 PMCID: PMC5985312 DOI: 10.3389/fimmu.2018.01105] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 05/02/2018] [Indexed: 12/13/2022] Open
Abstract
Overcrowding conditions and temperatures shifts regularly manifest in large-scale infections of farmed fish, resulting in economic losses for the global aquaculture industries. Increased understanding of the functional mechanisms of fish antimicrobial host defenses is an important step forward in prevention of pathogen-induced morbidity and mortality in aquaculture setting. Like other vertebrates, macrophage-lineage cells are integral to fish immune responses and for this reason, much of the recent fish immunology research has focused on fish macrophage biology. These studies have revealed notable similarities as well as striking differences in the molecular strategies by which fish and higher vertebrates control their respective macrophage polarization and functionality. In this review, we address the current understanding of the biological mechanisms of teleost macrophage functional heterogeneity and immunity, focusing on the key cytokine regulators that control fish macrophage development and their antimicrobial armamentarium.
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Affiliation(s)
- Leon Grayfer
- Department of Biological Sciences, George Washington University, Washington, DC, United States
| | - Baris Kerimoglu
- Department of Biological Sciences, George Washington University, Washington, DC, United States
| | - Amulya Yaparla
- Department of Biological Sciences, George Washington University, Washington, DC, United States
| | | | - Jiasong Xie
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Miodrag Belosevic
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
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5
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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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Forsgren S, Grimsholm O, Dalén T, Rantapää-Dahlqvist S. Measurements in the Blood of BDNF for RA Patients and in Response to Anti-TNF Treatment Help Us to Clarify the Magnitude of Centrally Related Pain and to Explain the Relief of This Pain upon Treatment. Int J Inflam 2011; 2011:650685. [PMID: 21755028 PMCID: PMC3132632 DOI: 10.4061/2011/650685] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2011] [Accepted: 04/19/2011] [Indexed: 12/31/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) is a neurotrophin with functions related to neuronal survival/proliferation processes and inflammation. BDNF is also an important central pain mediator. The levels of BDNF have been found to be high for RA patients with severe disease and to become lowered in response to anti-TNF treatment. New information says that the levels of BDNF in the blood parallel the BDNF concentrations in the brain and that BDNF can pass the blood-brain barrier. Furthermore, most of the circulating BDNF is produced in the brain. Habitual and regular exercise, in contrast to temporary exercise, does also lead to a lowering of BDNF blood levels. Both anti-TNF treatment and habitual and regular exercise do have pain-relieving effects. It might be that the pain-relieving effect of anti-TNF treatment is related to an affection of central neuronal regions, hereby influencing BDNF production. Measurements of BDNF in the blood help us to clarify the magnitude of centrally related pain for RA patients and help us to explain the relief of this pain in response to anti-TNF treatment.
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Affiliation(s)
- Sture Forsgren
- Anatomy Section, Department of Integrative Medical Biology, Umeå University, 901 87 Umeå, Sweden
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7
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Ponomarev SY, Audie J. Computational prediction and analysis of the DR6-NAPP interaction. Proteins 2011; 79:1376-95. [DOI: 10.1002/prot.22962] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 11/02/2010] [Accepted: 11/24/2010] [Indexed: 01/14/2023]
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p75 neurotrophin receptor mediates apoptosis in transit-amplifying cells and its overexpression restores cell death in psoriatic keratinocytes. Cell Death Differ 2010; 18:948-58. [PMID: 21151024 DOI: 10.1038/cdd.2010.162] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
p75 neurotrophin receptor (p75NTR) belongs to the TNF-receptor superfamily and signals apoptosis in many cell settings. In human epidermis, p75NTR is mostly confined to the transit-amplifying (TA) sub-population of basal keratinocytes. Brain-derived neurotrophic factor (BDNF) or neurotrophin-4 (NT-4), which signals through p75NTR, induces keratinocyte apoptosis, whereas β-amyloid, a ligand for p75NTR, triggers caspase-3 activation to a greater extent in p75NTR transfected cells. Moreover, p75NTR co-immunoprecipitates with NRAGE, induces the phosphorylation of c-Jun N-terminal kinase (JNK) and reduces nuclear factor kappa B (NF-κB) DNA-binding activity. p75NTR also mediates pro-NGF-induced keratinocyte apoptosis through its co-receptor sortilin. Furthermore, BDNF or β-amyloid cause cell death in TA, but not in keratinocyte stem cells (KSCs) or in p75NTR silenced TA cells. p75NTR is absent in lesional psoriatic skin and p75NTR levels are significantly lower in psoriatic than in normal TA keratinocytes. The rate of apoptosis in psoriatic TA cells is significantly lower than in normal TA cells. BDNF or β-amyloid fail to induce apoptosis in psoriatic TA cells, and p75NTR retroviral infection restores BDNF- or β-amyloid-induced apoptosis in psoriatic keratinocytes. These results demonstrate that p75NTR has a pro-apoptotic role in keratinocytes and is involved in the maintenance of epidermal homeostasis.
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Grayfer L, Belosevic M. Molecular characterization of tumor necrosis factor receptors 1 and 2 of the goldfish (Carassius aurutus L.). Mol Immunol 2009; 46:2190-9. [DOI: 10.1016/j.molimm.2009.04.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Accepted: 04/16/2009] [Indexed: 11/24/2022]
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10
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Abram M, Wegmann M, Fokuhl V, Sonar S, Luger EO, Kerzel S, Radbruch A, Renz H, Zemlin M. Nerve growth factor and neurotrophin-3 mediate survival of pulmonary plasma cells during the allergic airway inflammation. THE JOURNAL OF IMMUNOLOGY 2009; 182:4705-12. [PMID: 19342646 DOI: 10.4049/jimmunol.0802814] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Allergen-specific Abs play a pivotal role in the induction and maintenance of allergic airway inflammation. During secondary immune responses, plasma cell survival and Ab production is mediated by extrinsic factors provided by the local environment (survival niches). It is unknown whether neurotrophins, a characteristic marker of allergic airway inflammation, influence plasma cell survival in the lung. Using a mouse model of allergic asthma, we found that plasma cells from the lung and spleen are distinct subpopulations exhibiting differential expression patterns of neurotrophins and their receptors (Trks). In vitro, the nerve growth factor (NGF) and neurotrophin-3 (NT3) led to a dose-dependent increase in viability of isolated pulmonary plasma cells due to up-regulation of the antiapoptotic Bcl2 pathway. In parallel, the expression of transcription factors that stimulate the production of immunoglobulins (X-box binding protein 1 and NF-kappaB subunit RelA) was enhanced in plasma cells treated with NGF and NT3. These findings were supported in vivo. When the NGF pathway was blocked by intranasal application of a selective TrkA inhibitor, sensitized mice showed reduced numbers of pulmonary plasma cells and developed lower levels of allergen-specific and total serum IgE in response to OVA inhalation. This suggests that in the allergic airway inflammation, NGF/TrkA-mediated pulmonary IgE production contributes significantly to serum-IgE levels. We conclude that the neurotrophins NGF and NT3 act as survival factors for pulmonary plasma cells and thus are important regulators of the local Ab production in the allergic airway disease.
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Affiliation(s)
- Melanie Abram
- Department of Clinical Chemistry and Molecular Diagnostics, Philipps-University Marburg, Marburg, Germany
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11
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McDonald TG, Scott SA, Kane KM, Kawaja MD. Proteomic assessment of sympathetic ganglia from adult mice that possess null mutations of ExonIII or ExonIV in the p75 neurotrophin receptor gene. Brain Res 2009; 1253:1-14. [PMID: 19046947 DOI: 10.1016/j.brainres.2008.11.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 10/24/2008] [Accepted: 11/01/2008] [Indexed: 01/02/2023]
Abstract
Neurotrophins, such as nerve growth factor (NGF), are capable of binding to the transmembrane p75 neurotrophin receptor (p75NTR), which regulates a variety of cellular responses including apoptosis and axonal elongation. While the development of mutant mouse strains that lack functional p75NTR expression has provided further insight into the importance of this neurotrophin receptor, there remains a paucity of information concerning how the loss of p75NTR expression may alter neural phenotypes. To address this issue, we assessed the proteome of the cervical sympathetic ganglia from two mutant lines of mice, which were compared to the ganglionic proteome of age-matched wild type mice. The ganglionic proteome of mice possessing two mutant alleles of either exonIII or exonIV for the p75NTR gene displayed detectable alterations in levels of Lamin A, tyrosine hydroxylase, and Annexin V, as compared to ganglionic proteome of wild type mice. Decreased expression of the basic isoform of tyrosine hydroxylase may be linked to perturbed NGF signaling in the absence of p75NTR in mutant mice. Stereological measurement showed significant increases in the number of sympathetic neurons in both lines of p75NTR-deficient mice, relative to wild type mice. This enhanced survival of sympathetic neurons coincides with shifts toward the more basic isoforms of Annexin V in mutant mice. This study, in addition to providing the first comparative proteomic assessment of sympathetic ganglia, sheds new light onto the phenotypic changes that occur as a consequence of a loss of p75NTR expression in adult mice.
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Affiliation(s)
- Todd G McDonald
- Centre for Neuroscience Studies, Queen's University, Kingston, ON, Canada
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12
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Freund-Michel V, Frossard N. The nerve growth factor and its receptors in airway inflammatory diseases. Pharmacol Ther 2007; 117:52-76. [PMID: 17915332 DOI: 10.1016/j.pharmthera.2007.07.003] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 07/30/2007] [Indexed: 11/16/2022]
Abstract
The nerve growth factor (NGF) belongs to the neurotrophin family and induces its effects through activation of 2 distinct receptor types: the tropomyosin-related kinase A (TrkA) receptor, carrying an intrinsic tyrosine kinase activity in its intracellular domain, and the receptor p75 for neurotrophins (p75NTR), belonging to the death receptor family. Through activation of its TrkA receptor, NGF activates signalling pathways, including phospholipase Cgamma (PLCgamma), phosphatidyl-inositol 3-kinase (PI3K), the small G protein Ras, and mitogen-activated protein kinases (MAPK). Through its p75NTR receptor, NGF activates proapoptotic signalling pathways including the MAPK c-Jun N-terminal kinase (JNK), ceramides, and the small G protein Rac, but also activates pathways promoting cell survival through the transcription factor nuclear factor-kappaB (NF-kappaB). NGF was first described by Rita Levi-Montalcini and collaborators as an important factor involved in nerve differentiation and survival. Another role for NGF has since been established in inflammation, in particular of the airways, with increased NGF levels in chronic inflammatory diseases. In this review, we will first describe NGF structure and synthesis and NGF receptors and their signalling pathways. We will then provide information about NGF in the airways, describing its expression and regulation, as well as pointing out its potential role in inflammation, hyperresponsiveness, and remodelling process observed in airway inflammatory diseases, in particular in asthma.
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Affiliation(s)
- V Freund-Michel
- EA 3771 Inflammation and Environment in Asthma, University Louis Pasteur-Strasbourg I, Faculty of Pharmacy, Illkirch, France.
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Abstract
Neurotrophins are known to have growth, survival-promoting, and healing effects. The importance of neurotrophins in ulcerative colitis (UC) is, however, unclear. Recent studies in our group revealed that an occurrence of marked changes in neurotrophin expression patterns was related to a worsening of the disease process. There was thus an upregulation for the lamina propria cells but a downregulation in nerve structures concerning neurotrophin expressions in severe UC. The observations show that changes in the neurotrophin system are a part of the disease process in UC and are of interest as treatments interfering with neurotrophin effects in other situations have been found to have trophic and healing effects.
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Affiliation(s)
- Malin Johansson
- Department of Integrative Medical Biology, Umeå University, SE-901 87 Umeå, Sweden.
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14
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Johansson M, Norrgård O, Forsgren S. Study of expression patterns and levels of neurotrophins and neurotrophin receptors in ulcerative colitis. Inflamm Bowel Dis 2007; 13:398-409. [PMID: 17206664 DOI: 10.1002/ibd.20072] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Neurotrophins may be involved in ulcerative colitis (UC). Yet, it is unclear whether if their effects should be blocked. METHODS In this study, the neurotrophins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) and their receptors were examined by immunohistochemistry, ELISA, and RT-PCR. RESULTS BDNF immunoreaction was detected in nerve structures in particular, and NGF immunoreaction was detected in lamina propria cells. Cellular NGF immunoreaction was generally observed to be higher in the mucosa of UC patients than in the controls. In addition, UC patients demonstrated significantly higher p75 immunoreaction (P = 0.010) in lamina propria cells. The controls expressed significantly higher BDNF immunoreaction in the nerve structures than did UC patients (P = 0.000). However, the UC group showed marked interindividual variation in expression of neurotrophins and neurotrophin receptors. This included variation at the mRNA level for NGF. Differences with the controls were most pronounced in UC specimens demonstrating great infiltration of inflammatory cells and marked tissue derangement. Corticosteroid treatment seemed to affect neurotrophin production in lamina propria cells but not in nerve structures. These observations demonstrate that up-regulation and down-regulation of neurotrophins occur in different structural components in response to the disease process. Massive inflammation seemed to be correlated with decreased neurotrophin immunoreaction in nerve structures, but there was a tendency toward increased neurotrophin production in lamina propria cells. CONCLUSIONS Our study shows that UC patients are not a uniform group in their expression of neurotrophins, a fact that should be considered when discussing therapeutic interventions.
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Affiliation(s)
- Malin Johansson
- Department of Integrative Medical Biology, Section of Anatomy, Umeå University, Umeå, Sweden.
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15
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Capsoni S, Cattaneo A. On the molecular basis linking Nerve Growth Factor (NGF) to Alzheimer's disease. Cell Mol Neurobiol 2006; 26:619-33. [PMID: 16944323 DOI: 10.1007/s10571-006-9112-2] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Accepted: 09/26/2005] [Indexed: 01/27/2023]
Abstract
1. Alzheimer's disease (AD) is pathologically defined by the deposition of amyloid peptide and neurofibrillary tangles and is characterized by a progressive loss of cognition and memory function, due to marked cortical cholinergic depletion. 2. Cholinergic cortical innervation is provided by basal forebrain cholinergic neurons. The neurotrophin Nerve Growth Factor (NGF) promotes survival and differentiation of basal forebrain cholinergic neurons. 3. This assertion has been at the basis of the hypothesis developed in the last 20 years, whereby NGF deprivation would be one of the factor involved in the etiology of sporadic forms of AD. 4. In this review, we shall summarize data that lead to the production and characterization of a mouse model for AD (AD11 anti-NGF mice), based on the expression of transgenic antibodies neutralizing NGF. The AD-like phenotype of AD11 mice will be discussed on the basis of recent studies that have posed NGF and its precursor pro-NGF back to the stage of AD-like neurodegeneration, showing the involvement of the precursor pro-NGF in one of the cascades leading to AD neurodegeneration.
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Affiliation(s)
- Simona Capsoni
- Lay Line Genomics S.p.A., Via di Castel Romano 100, 00128, Rome, Italy.
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Lipnik-Stangelj M. Multiple role of histamine H1-receptor-PKC-MAPK signalling pathway in histamine-stimulated nerve growth factor synthesis and secretion. Biochem Pharmacol 2006; 72:1375-81. [PMID: 16884695 DOI: 10.1016/j.bcp.2006.06.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Revised: 06/16/2006] [Accepted: 06/21/2006] [Indexed: 11/20/2022]
Abstract
Histamine is a potent stimulator of nerve growth factor (NGF) production in the central nerve system and in the periphery as well. In this review, the biochemical mechanisms of histamine-stimulated NGF synthesis and secretion, and interactions between histamine, interleukin-1beta, and interleukin-6 are discussed. The main signalling pathway, involved in the stimulation of NGF production by histamine, includes activation of histamine H(1)-receptor, stimulation of Ca(2+)-dependent protein kinase C and mitogen-activated protein kinase. The same signalling pathway is involved in the interactions between histamine, interleukin-1beta, and interleukin-6, where NGF secretion is amplified. Whereas histamine and interleukin-1beta cause additive stimulatory effect on NGF secretion, interaction between histamine and interleukin-6 causes a long-term synergism. Thus, activation of histamine H(1)-receptor-protein kinase C-mitogen-activated protein kinase signalling pathway plays a crucial role not only in the direct stimulation of NGF secretion by histamine, but also in the indirect stimulation via different types of interactions between histamine, interleukin-1beta, and interleukin-6, which may have important therapeutic implications in modulation of NGF production.
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Affiliation(s)
- Metoda Lipnik-Stangelj
- Department of Pharmacology and Experimental Toxicology, Faculty of Medicine, Korytkova 2, SI-1000 Ljubljana, Slovenia.
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Dhanoa NK, Krol KM, Jahed A, Crutcher KA, Kawaja MD. Null mutations for exon III and exon IV of the p75 neurotrophin receptor gene enhance sympathetic sprouting in response to elevated levels of nerve growth factor in transgenic mice. Exp Neurol 2006; 198:416-26. [PMID: 16488412 DOI: 10.1016/j.expneurol.2005.12.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Revised: 11/01/2005] [Accepted: 12/10/2005] [Indexed: 11/21/2022]
Abstract
Under normal conditions, expression of the p75 neurotrophin receptor (p75NTR) by sympathetic neurons can increase the affinity of the signaling receptor, trkA, to target-derived nerve growth factor (NGF) at distal axons. We have previously reported that sprouting of sympathetic axons into NGF-rich target tissues is enhanced when p75NTR expression is perturbed, leading to the postulate that p75NTR may restrain sympathetic sprouting in response to elevated NGF levels. These observations were made using mice having a null mutation of the third p75NTR exon, a line that may express a hypomorphic form of this receptor. Since mice carrying a null mutation of the fourth p75NTR exon may not express a similar splice variant, we sought to determine whether these animals possess the same phenotype of enhanced sympathetic sprouting in response to elevated levels of NGF. Both lines of transgenic mice lacking p75NTR displayed similar degrees of sympathetic axonal sprouting into the cerebellum and trigeminal ganglia, two target tissues having elevated levels of NGF protein. Furthermore, the densities of sympathetic axons in both targets were significantly greater than those observed in age-matched NGF transgenic siblings expressing full-length p75NTR. Our new findings provide a comparative analysis of the phenotype in two independent mutations of the same neurotrophin receptor, revealing that p75NTR plays an important role in restricting sympathetic sprouting in response to higher NGF levels.
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Affiliation(s)
- Navnish K Dhanoa
- Department of Anatomy and Cell Biology, Queen's University, Kingston, ON, Canada K7L 3N6
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18
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Frossard N, Freund V, Advenier C. Nerve growth factor and its receptors in asthma and inflammation. Eur J Pharmacol 2005; 500:453-65. [PMID: 15464052 DOI: 10.1016/j.ejphar.2004.07.044] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/01/2004] [Indexed: 12/28/2022]
Abstract
Nerve growth factor (NGF) is a high molecular weight peptide that belongs to the neurotrophin family. It is synthesized by various structural and inflammatory cells and activates two types of receptors, the TrkA (tropomyosin-receptor kinase A) receptor and the p75(NTR) receptor, in the death receptor family. NGF was first studied for its essential role in neuronal growth and survival. Recent reports indicate that it may also help mediate inflammation, especially in the airways. Several studies in animals have reported that NGF may induce bronchial hyperresponsiveness, an important feature of asthma, by increasing sensory innervation. It may also induce migration and activation of inflammatory cells, which infiltrate the bronchial mucosa, and of structural cells, including epithelial, smooth muscle cells and pulmonary fibroblasts. Increased NGF expression and release is observed in asthma patients after bronchial provocation with allergen. Taken together, the data from the literature suggest that NGF may play a role in inflammation, bronchial hyperresponsiveness and airway remodelling in asthma and may help us to understand the neuro-immune cross-talk involved in chronic inflammatory airway diseases.
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Affiliation(s)
- Nelly Frossard
- EA 3771 "Inflammation and Environment in Asthma" Université Louis Pasteur-Strasbourg-I, Faculté de Pharmacie, Illkirch, France.
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19
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Abstract
INTRODUCTION The nerve growth factor (NGF) is known as a factor involved in neuronal growth and survival. From recent studies it may also be considered as a mediator of inflammation, in particular in the airways. STATE OF ART Several animal studies have shown that NGF may increase the sensory innervation, and participate in the bronchial hyperresponsiveness and inflammation observed in the airways of asthmatic patients. Different cell types are capable of secreting NGF: inflammatory cells that infiltrate the bronchial mucosa, and structural cells such as epithelial cells, smooth muscle cells and pulmonary fibroblasts. Furthermore, increased NGF levels have been detected in the bronchoalveolar lavage fluid from asthmatic patients. PERSPECTIVES AND CONCLUSION Altogether, these results suggest that NGF may play a role in inflammation, bronchial hyperresponsiveness and airway remodelling in asthma, and may lead to a better understanding of the mechanisms occurring in chronic inflammatory diseases, in particular asthma.
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Affiliation(s)
- V Freund
- EA 3771 Inflammation et environnement dans l'asthme, Université Louis Pasteur-Strasbourg-I, Faculté de Pharmacie, Illkirch, France
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20
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Langevin C, Jaaro H, Bressanelli S, Fainzilber M, Tuffereau C. Rabies virus glycoprotein (RVG) is a trimeric ligand for the N-terminal cysteine-rich domain of the mammalian p75 neurotrophin receptor. J Biol Chem 2002; 277:37655-62. [PMID: 12163480 DOI: 10.1074/jbc.m201374200] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rabies virus glycoprotein (RVG) is a trimeric and surface-exposed viral coat protein that has been shown to interact with the murine p75 neurotrophin receptor. We have investigated binding of RVG to p75 and describe several features that distinguish the p75-RVG interaction from conventional neurotrophin binding to p75. RVG binds mammalian but not avian p75 and does not bind to any of the Trk neurotrophin receptors. The mammalian p75 specificity of RVG binding may partly explain the phyletic specificity of rabies infection. Radioiodinated nerve growth factor (NGF) and RVG both bind to rat p75 but do not compete with each other's binding site. Although neurotrophins bind to the second and third cysteine-rich domains (CRD) of p75, RVG specifically interacts with high affinity (K(d) 30-35 pm) with the first CRD (CRD1). Substitution of Gln(33) in p75-CRD1 by Glu completely abolishes RVG binding. Our data therefore firmly establish RVG as a trimeric high affinity ligand for a non-neurotrophin binding site on p75. Interestingly, the CRD1 in another TNF/NGF family receptor was recently shown to be involved in the binding of the herpes virus glycoprotein gD, suggesting that the CRD1 of TNF/NGF family members may be a widely used binding domain for viral glycoproteins.
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Affiliation(s)
- Christelle Langevin
- Laboratoire de Virologie Moléculaire et Structurale, Centre National de la Recherche Scientifique-Institut National de la Recherche Agronomique, 91198 Gif-sur-Yvette, France
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21
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Jorissen RN, Treutlein HR, Epa VC, Burgess AW. Modeling the epidermal growth factor -- epidermal growth factor receptor l2 domain interaction: implications for the ligand binding process. J Biomol Struct Dyn 2002; 19:961-72. [PMID: 12023799 DOI: 10.1080/07391102.2002.10506800] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Signaling from the epidermal growth factor (EGF) receptor is triggered by the binding of ligands such as EGF or transforming growth factor alpha (TGF-alpha) and subsequent receptor dimerization. An understanding of these processes has been hindered by the lack of structural information about the ligand-bound, dimerized EGF receptor. Using an NMR-derived structure of EGF and a homology model of the major ligand binding domain of the EGF receptor and experimental data, we modeled the binding of EGF to this EGF receptor fragment. In this low resolution model of the complex, EGF sits across the second face of the EGF receptor L2 domain and EGF residues 10-16, 36-37, 40-47 bind to this face. The structural model is largely consistent with previously published NMR data describing the residues of TGF-alpha which interact strongly with the EGF receptor. Other EGF residues implicated in receptor binding are accounted by our proposal that the ligand binding is a two-step process with the EGF binding to at least one other site of the receptor. This three-dimensional model is expected to be useful in the design of ligand-based antagonists of the receptor.
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Affiliation(s)
- Robert N Jorissen
- The Ludwig Institute for Cancer Research, Post Office Box 2008, Royal Melbourne Hospital, Parkville, Victoria, 3050, Australia.
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22
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Kilár F, Visegrády B. Mapping of stereoselective recognition sites on human serum transferrin by capillary electrophoresis and molecular modelling. Electrophoresis 2002; 23:964-71. [PMID: 11920884 DOI: 10.1002/1522-2683(200203)23:6<964::aid-elps964>3.0.co;2-b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Stereoselective recognition of chiral compounds can be used for mapping of surface interaction sites on proteins. Iron-free human serum transferrin is a suitable chiral selector in capillary electrophoresis used in native form in solution. Separation of optical isomers of tryptophan-methylester, tryptophan-ethylester and tryptophan-butylester and various drugs were studied in capillary zone electrophoresis applying a distinct transferrin zone prior to sample injection. Changes in the electrophoretic patterns (i.e., in the migration properties) of the molecules reflected the possible interactions with the protein. The tryptophan derivatives and eight drugs possessed stereoselective interactions, seven drugs showed interactions without appreciable chiral separation, and the others did not present any direct complexation with the protein molecules. Molecular modelling was performed to characterize the binding areas at the iron binding site of iron-free transferrin. The docking of tryptophan derivatives on transferrin showed that the R-enantiomers possess a stronger complexation with transferrin, whereas the S-enantiomers are bound by weaker interactions, which is in excellent agreement with the capillary electrophoresis results, where the R-enantiomers were always retarded stronger by transferrin. A ranking of drugs by the lipo score parameter of the docking shows an accordance with the stereoselective interactions by the protein.
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Affiliation(s)
- Ferenc Kilár
- Central Research Laboratory, Faculty of Medicine, University of Pécs, Szigeti út. 12, H-7643 Pécs, Hungary.
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23
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von Schack D, Casademunt E, Schweigreiter R, Meyer M, Bibel M, Dechant G. Complete ablation of the neurotrophin receptor p75NTR causes defects both in the nervous and the vascular system. Nat Neurosci 2001; 4:977-8. [PMID: 11559852 DOI: 10.1038/nn730] [Citation(s) in RCA: 197] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2001] [Accepted: 08/29/2001] [Indexed: 11/08/2022]
Affiliation(s)
- D von Schack
- Department of Neurobiochemistry, Max Planck Institute of Neurobiology, Am Klopferspitz 18a, D-82152 Martinsried, Germany
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24
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Crockett DP, Harris SL, Egger MD. Neurotrophin receptor (p75) in the trigeminal thalamus of the rat: development, response to injury, transient vibrissa-related patterning, and retrograde transport. THE ANATOMICAL RECORD 2000; 259:446-60. [PMID: 10903536 DOI: 10.1002/1097-0185(20000801)259:4<446::aid-ar80>3.0.co;2-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We report on the transient, patterned expression of p75 in the ventrobasal (VB) thalamus, the major thalamic relay for somatosensation. We immunostained the brains of developing rats ranging in age from embryonic day (E) 14.5 to postnatal day (PD) 15 with an antibody against p75. To compare p75 expression with the developing synaptic organization within VB, we also immunolocalized the synaptic-vesicle-associated protein, synaptophysin (SYN), on alternate sections. p75-immunoreactivity (IR) was dense and uniform in the ventroposterior medial nucleus (VPM) in the late embryonic and early postnatal periods (E 16.5 to PD 3). In contrast, from PD 4-10, p75-IR in the VPM was patterned, reminiscent of cytochrome-oxidase-stained barreloids, a characteristic feature of the VB in rodents. By PD 14, p75-IR in the VPM was no longer detectable. The ventroposterior lateral nucleus (VPL), in contrast, exhibited no p75-IR. No p75-IR was detected in the ventroposterior lateral nucleus (VPL) at any developmental stage in which VPM could be distinguished from VPL. Light, but clearly patterned SYN-IR, first detectable on PD 2-3, increased in intensity in both VPL and VPM through PD 15. Sectioning the infraorbital nerve on PD 0 resulted in blurred patterns of p75- and SYN-IR within VPM in PD 7-9 rat pups. Removing large portions of the somatosensory cortex on PD 0 resulted in subsequent greatly reduced p75- and SYN-IR within VB. To specify the source of the p75-IR terminals, we stereotaxically injected into the VPM of PD 4-5 rats a monoclonal antibody to p75. One to 2 days later, IR of retrogradely transported p75 antibodies could be traced within axons and cell bodies of neurons associated with the trigeminothalamic pathway through the caudal diencephalon and mesencephalon; labelling was confined to the contralateral trigeminal principal sensory nucleus. The observed, transiently patterned p75-IR in VPM the early postpartum period suggests a role for p75 in synaptogenesis and pattern formation.
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Affiliation(s)
- D P Crockett
- Department of Neuroscience and Cell Biology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854-5635, USA.
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25
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Shamovsky IL, Ross GM, Riopelle RJ, Weaver DF. The interaction of neurotrophins with the p75NTR common neurotrophin receptor: a comprehensive molecular modeling study. Protein Sci 1999; 8:2223-33. [PMID: 10595525 PMCID: PMC2144181 DOI: 10.1110/ps.8.11.2223] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Neurotrophins are a family of proteins with pleiotropic effects mediated by two distinct receptor types, namely the Trk family, and the common neurotrophin receptor p75NTR. Binding of four mammalian neurotrophins, nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4/5), to p75NTR is studied by molecular modeling based on X-ray structures of the neurotrophins and the extracellular domain of p55TNFR, a homologue of p75NTR. The model of neurotrophin/receptor interactions suggests that the receptor binding domains of neurotrophins (loops I and IV) are geometrically and electrostatically complementary to a putative binding site of p75NTR, formed by the second and part of the third cysteine-rich domains. Geometric match of neurotrophin/receptor binding domains in the complexes, as characterized by shape complementarity statistic Sc, is comparable to known protein/protein complexes. All charged residues within the loops I and IV of the neurotrophins, previously determined as being critical for p75NTR binding, directly participate in receptor binding in the framework of the model. Principal residues of the binding site of p75NTR include Asp47, Lys56, Asp75, Asp76, Asp88, and Glu89. The additional involvement of Arg80 and Glu53 is specific for NGF and BDNF, respectively, and Glu73 participates in binding with NT-3 and NT-4/5. Neurotrophins are likely to induce similar, but not identical, conformational changes within the p75NTR binding site.
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Affiliation(s)
- I L Shamovsky
- Department of Medicine, Queen's University, Kingston, Ontario, Canada
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26
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Crockett DP, Wang L, Zhang RX, Egger MD. Distribution of the low-affinity neurotrophin receptor (p75) in the developing trigeminal brainstem complex in the rat. Anat Rec (Hoboken) 1999; 254:549-65. [PMID: 10203262 DOI: 10.1002/(sici)1097-0185(19990401)254:4<549::aid-ar10>3.0.co;2-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The low-affinity neurotrophin receptor (p75) binds all members of the neurotrophin family. In the rat, during the first week postpartum, dense p75-immunoreactivity (IR) is present throughout all components of the trigeminal brainstem complex (TBC), largely associated with primary sensory afferents. Within subnucleus caudalis (SpC) of the TBC, intense p75-IR is present in all laminae at birth. During the second and third postnatal weeks, p75-IR in SpC gradually fades within the deeper laminae, becoming generally restricted in the adult to laminae I and II. Similar declines in p75-IR intensity occur in the subnucleus oralis (SpO); in the SpO in the adult, p75-IR is confined to the dorsalmost portion of SpO. In subnucleus interpolaris, an emerging, vibrissa-related pattern of p75-IR is detectable on PD0 (first 24 hr postpartum), which becomes fully differentiated during PD4-PD7. However, this pattern gradually disappears during the third postnatal week. Ventrally in the nucleus principalis (PrV), a pattern of p75-IR that mirrors the topographical arrangement of the vibrissae is detectable by PD0-PD1, is fully differentiated by the end of the first postnatal week, and persists into adulthood. Perinatal unilateral sectioning of the infraorbital nerve on PD0-PD1, but not as late as PD4, disrupts p75-IR patterning in the adult PrV. Although p75 appears to be associated with primary afferent pattern formation, to determine whether it is essential, we examined mutant mice unable to form functional p75. In the TBC of these knockout mice, examined as adults, patterns of cytochrome oxidase staining (which parallel those of p75-IR) appeared to be normal. In summary, during early development, p75 is widely expressed in the TBC during periods of active synaptogenesis and pattern formation, whereas in the adult, its expression is restricted to association with populations of primary sensory afferents. However, the absence of functional p75 in genetically altered mice does not appear to prevent primary afferent pattern formation.
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Affiliation(s)
- D P Crockett
- Department of Neuroscience and Cell Biology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway 08854-5635, USA.
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27
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Abstract
A subset of cytokine mediators belonging to the tumor necrosis factor (TNF) family cause apoptosis, acting through receptors and signaling pathways that have recently come to light. Further, at least one autoimmune disease results from a defined defect of apoptosis (mutations of the Fas ligand or its receptor). It is offered that many, and perhaps most autoimmune diseases may result from primary defects of apoptosis. Such defects may cause reflexive overproduction of TNF and other pro-apoptotic cytokines. The collateral damage produced by these mediators may be of pathogenetic importance in complex autoimmune disorders such as rheumatoid arthritis and Crohn disease, wherein TNF blockade is known to have ameliorative effects.
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Affiliation(s)
- B Beutler
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas 75235-9050, USA.
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28
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29
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Krüttgen A, Heymach JV, Kahle PJ, Shooter EM. The role of the nerve growth factor carboxyl terminus in receptor binding and conformational stability. J Biol Chem 1997; 272:29222-8. [PMID: 9361001 DOI: 10.1074/jbc.272.46.29222] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The role of the nerve growth factor (NGF) carboxyl terminus in the function of NGF is not well understood. Previous work showed that deletion of residues 112-120 abolished NGF bioactivity. Several mutagenesis studies, however, have localized the binding sites of the two NGF receptors, p75 and TrkA, to other regions of the NGF molecule. To investigate the role of the NGF COOH terminus, we performed a detailed structure-function analysis of this region by deleting stepwise each of the nine COOH-terminal residues as well as constructing six point mutants. We found that point mutations within the 111-115 region, but not deletion of residues 116-120, significantly decreased NGF bioactivity, as determined by TrkA tyrosine phosphorylation and neurite outgrowth from PC12 cells. Mutation of the absolutely conserved Leu112 led to severely disrupted p75 binding on A875 cells but had only a modest effect on TrkA binding to MG87-TrkA fibroblasts. This suggests that the p75 binding surface is more extended than previously believed and includes not only charged residues within loops 1 and 5 but also spatially discontinuous, uncharged residues in a region where the NH2 and COOH termini are in close proximity. Unexpectedly, deletion of COOH-terminal residues beyond Ala116 led to significantly decreased stability. These results demonstrate that residues 111-115, but not residues 116-120, are important for both the structural stability and biological activity of NGF.
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Affiliation(s)
- A Krüttgen
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305-5401, USA
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Hileman MR, Chapman BS, Rabizadeh S, Krishnan VV, Bredesen D, Assa-Munt N, Plesniak LA. A cytoplasmic peptide of the neurotrophin receptor p75NTR: induction of apoptosis and NMR determined helical conformation. FEBS Lett 1997; 415:145-54. [PMID: 9350985 DOI: 10.1016/s0014-5793(97)01113-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The neurotrophin receptor (NTR) and tumor necrosis factor receptor family of receptors regulate apoptotic cell death during development and in adult tissues [Beutler and van Huffel, Science 264 (1994) 667-668]. We have examined a fragment of p75NTR from the carboxyl terminus of the receptor and a variant form of this peptide via NMR techniques and in vitro assays for apoptotic activity. The wild type peptide induces apoptosis and adopts a helical conformation oriented parallel to the surface of lipid micelles, whereas the variant form adopts a non-helical conformation in the presence of lipid and shows no activity. These experiments suggest a link between structure and function of the two peptides.
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Affiliation(s)
- M R Hileman
- Department of Chemistry, University of San Diego, CA 92110, USA
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31
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Abstract
Activation specific tyrosine kinase receptors by neurotrophins accounts for the longest known biological actions of the neurotrophins, in particular the promotion of neuronal survival. However, recent studies have revealed that nerve growth factor, the neurotrophin regarded as best understood, also activates a signalling pathway by binding to the neurotrophin receptor p75(NTR). This receptor belongs to the tumor necrosis factor receptor family and lacks intrinsic catalytic activity. The p75(NTR) receptor binds all neurotrophins with nanomolar affinity; however, nerve growth factor seems to be uniquely able to activate it, causing the death of trkA-negative neurons during normal development. Thus, nerve growth factor prevents programmed cell death through its receptor TrkA, but promotes it by signalling through p75(NTR).
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Affiliation(s)
- G Dechant
- Max-Planck Institute for Psychiatry, Department of Neurobiochemistry Am Klopferspitz 18A, 82152 Martinsried, Germany.
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32
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Abstract
Functional recovery from peripheral nerve injury and repair depends on a multitude of factors, both intrinsic and extrinsic to neurons. Neuronal survival after axotomy is a prerequisite for regeneration and is facilitated by an array of trophic factors from multiple sources, including neurotrophins, neuropoietic cytokines, insulin-like growth factors (IGFs), and glial-cell-line-derived neurotrophic factors (GDNFs). Axotomized neurons must switch from a transmitting mode to a growth mode and express growth-associated proteins, such as GAP-43, tubulin, and actin, as well as an array of novel neuropeptides and cytokines, all of which have the potential to promote axonal regeneration. Axonal sprouts must reach the distal nerve stump at a time when its growth support is optimal. Schwann cells in the distal stump undergo proliferation and phenotypical changes to prepare the local environment to be favorable for axonal regeneration. Schwann cells play an indispensable role in promoting regeneration by increasing their synthesis of surface cell adhesion molecules (CAMs), such as N-CAM, Ng-CAM/L1, N-cadherin, and L2/HNK-1, by elaborating basement membrane that contains many extracellular matrix proteins, such as laminin, fibronectin, and tenascin, and by producing many neurotrophic factors and their receptors. However, the growth support provided by the distal nerve stump and the capacity of the axotomized neurons to regenerate axons may not be sustained indefinitely. Axonal regenerations may be facilitated by new strategies that enhance the growth potential of neurons and optimize the growth support of the distal nerve stump in combination with prompt nerve repair.
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Affiliation(s)
- S Y Fu
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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