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Girych M, Kulig W, Enkavi G, Vattulainen I. How Neuromembrane Lipids Modulate Membrane Proteins: Insights from G-Protein-Coupled Receptors (GPCRs) and Receptor Tyrosine Kinases (RTKs). Cold Spring Harb Perspect Biol 2023; 15:a041419. [PMID: 37487628 PMCID: PMC10547395 DOI: 10.1101/cshperspect.a041419] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
Lipids play a diverse and critical role in cellular processes in all tissues. The unique lipid composition of nerve membranes is particularly interesting because it contains, among other things, polyunsaturated lipids, such as docosahexaenoic acid, which the body only gets through the diet. The crucial role of lipids in neurological processes, especially in receptor-mediated cell signaling, is emphasized by the fact that in many neuropathological diseases there are significant deviations in the lipid composition of nerve membranes compared to healthy individuals. The lipid composition of neuromembranes can significantly affect the function of receptors by regulating the physical properties of the membrane or by affecting specific interactions between receptors and lipids. In addition, it is worth noting that the ligand-binding pocket of many receptors is located inside the cell membrane, due to which lipids can even modulate the binding of ligands to their receptors. These mechanisms highlight the importance of lipids in the regulation of membrane receptor activation and function. In this article, we focus on two major protein families: G-protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs) and discuss how lipids affect their function in neuronal membranes, elucidating the basic mechanisms underlying neuronal function and dysfunction.
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Affiliation(s)
- Mykhailo Girych
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Waldemar Kulig
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Giray Enkavi
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
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2
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Lüningschrör P, Andreska T, Veh A, Wolf D, Giridhar NJ, Moradi M, Denzel A, Sendtner M. Calnexin controls TrkB cell surface transport and ER-phagy in mouse cerebral cortex development. Dev Cell 2023; 58:1733-1747.e6. [PMID: 37506696 DOI: 10.1016/j.devcel.2023.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 05/23/2023] [Accepted: 07/05/2023] [Indexed: 07/30/2023]
Abstract
Transactivation of Tropomyosin receptor kinase B (TrkB) by EGF leads to cell surface transport of TrkB, promoting its signaling responsiveness to brain-derived neurotrophic factor (BDNF), a critical process for proper cortical plate development. However, the mechanisms that regulate the transport of TrkB to the cell surface are not fully understood. Here, we identified Calnexin as a regulator for targeting TrkB either to the cell surface or toward autophagosomal processing. Calnexin-deficient mouse embryos show impaired cortical plate formation and elevated levels of transactivated TrkB. In Calnexin-depleted mouse neuronal precursor cells, we detected an impaired cell surface transport of TrkB in response to EGF and an impaired delivery to autophagosomes. Mechanistically, we show that Calnexin facilitates the interaction of TrkB with the ER-phagy receptor Fam134b, thereby targeting TrkB to ER-phagy. This mechanism appears as a critical process for fine-tuning the sensitivity of neurons to BDNF.
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Affiliation(s)
- Patrick Lüningschrör
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Thomas Andreska
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Alexander Veh
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Daniel Wolf
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Neha Jadhav Giridhar
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Mehri Moradi
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Angela Denzel
- Imperial Cancer Research Fund now Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany.
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3
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Underlying Mechanisms Involved in Gambling Disorder Severity: A Pathway Analysis Considering Genetic, Psychosocial, and Clinical Variables. Nutrients 2023; 15:nu15020418. [PMID: 36678289 PMCID: PMC9864492 DOI: 10.3390/nu15020418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 12/29/2022] [Accepted: 01/10/2023] [Indexed: 01/14/2023] Open
Abstract
Gambling Disorder (GD) has a complex etiology that involves biological and environmental aspects. From a genetic perspective, neurotrophic factors (NTFs) polymorphisms have been associated with the risk of developing GD. The aim of this study was to assess the underlying mechanisms implicated in GD severity by considering the direct and mediational relationship between different variables including genetic, psychological, socio-demographic, and clinical factors. To do so, we used genetic variants that were significantly associated with an increased risk for GD and evaluated its relationship with GD severity through pathway analysis. We found that the interaction between these genetic variants and other different biopsychological features predicted a higher severity of GD. On the one hand, the presence of haplotype block 2, interrelated with haplotype block 3, was linked to a more dysfunctional personality profile and a worse psychopathological state, which, in turn, had a direct link with GD severity. On the other hand, having rs3763614 predicted higher general psychopathology and therefore, higher GD severity. The current study described the presence of complex interactions between biopsychosocial variables previously associated with the etiopathogenesis and severity of GD, while also supporting the involvement of genetic variants from the NTF family.
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4
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Neuroprotective Action of Coumarin Derivatives through Activation of TRKB-CREB-BDNF Pathway and Reduction of Caspase Activity in Neuronal Cells Expressing Pro-Aggregated Tau Protein. Int J Mol Sci 2022; 23:ijms232112734. [PMID: 36361524 PMCID: PMC9654711 DOI: 10.3390/ijms232112734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/20/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022] Open
Abstract
Hyperphosphorylation and aggregation of the microtubule binding protein tau is a neuropathological hallmark of Alzheimer’s disease/tauopathies. Tau neurotoxicity provokes alterations in brain-derived neurotrophic factor (BDNF)/tropomycin receptor kinase B (TRKB)/cAMP-response-element binding protein (CREB) signaling to contribute to neurodegeneration. Compounds activating TRKB may therefore provide beneficial effects in tauopathies. LM-031, a coumarin derivative, has demonstrated the potential to improve BDNF signaling in neuronal cells expressing pro-aggregated ΔK280 tau mutant. In this study, we investigated if LM-031 analogous compounds provide neuroprotection effects through interaction with TRKB in SH-SY5Y cells expressing ΔK280 tauRD-DsRed folding reporter. All four LMDS compounds reduced tau aggregation and reactive oxygen species. Among them, LMDS-1 and -2 reduced caspase-1, caspase-6 and caspase-3 activities and promoted neurite outgrowth, and the effect was significantly reversed by knockdown of TRKB. Treatment of ERK inhibitor U0126 or PI3K inhibitor wortmannin decreased p-CREB, BDNF and BCL2 in these cells, implying that the neuroprotective effects of LMDS-1/2 are via activating TRKB downstream ERK, PI3K-AKT and CREB signaling. Furthermore, LMDS-1/2 demonstrated their ability to quench the intrinsic fluorescence of tryptophan residues within the extracellular domain of TRKB, thereby consolidating their interaction with TRKB. Our results suggest that LMDS-1/2 exert neuroprotection through activating TRKB signaling, and shed light on their potential application in therapeutics of Alzheimer’s disease/tauopathies.
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5
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Tosolini AP, Sleigh JN, Surana S, Rhymes ER, Cahalan SD, Schiavo G. BDNF-dependent modulation of axonal transport is selectively impaired in ALS. Acta Neuropathol Commun 2022; 10:121. [PMID: 35996201 PMCID: PMC9396851 DOI: 10.1186/s40478-022-01418-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 07/29/2022] [Indexed: 02/08/2023] Open
Abstract
Axonal transport ensures long-range delivery of essential cargoes between proximal and distal compartments, and is needed for neuronal development, function, and survival. Deficits in axonal transport have been detected at pre-symptomatic stages in the SOD1G93A and TDP-43M337V mouse models of amyotrophic lateral sclerosis (ALS), suggesting that impairments in this critical process are fundamental for disease pathogenesis. Strikingly, in ALS, fast motor neurons (FMNs) degenerate first whereas slow motor neurons (SMNs) are more resistant, and this is a currently unexplained phenomenon. The main aim of this investigation was to determine the effects of brain-derived neurotrophic factor (BDNF) on in vivo axonal transport in different α-motor neuron (MN) subtypes in wild-type (WT) and SOD1G93A mice. We report that despite displaying similar basal transport speeds, stimulation of wild-type MNs with BDNF enhances in vivo trafficking of signalling endosomes specifically in FMNs. This BDNF-mediated enhancement of transport was also observed in primary ventral horn neuronal cultures. However, FMNs display selective impairment of axonal transport in vivo in symptomatic SOD1G93A mice, and are refractory to BDNF stimulation, a phenotype that was also observed in primary embryonic SOD1G93A neurons. Furthermore, symptomatic SOD1G93A mice display upregulation of the classical non-pro-survival truncated TrkB and p75NTR receptors in muscles, sciatic nerves, and Schwann cells. Altogether, these data indicate that cell- and non-cell autonomous BDNF signalling is impaired in SOD1G93A MNs, thus identifying a new key deficit in ALS.
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Affiliation(s)
- Andrew P Tosolini
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK. .,UCL Queen Square Motor Neuron Disease Centre, University College London, London, WC1N 3BG, UK.
| | - James N Sleigh
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.,UCL Queen Square Motor Neuron Disease Centre, University College London, London, WC1N 3BG, UK.,UK Dementia Research Institute, University College London, London, WC1E 6BT, UK
| | - Sunaina Surana
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.,UCL Queen Square Motor Neuron Disease Centre, University College London, London, WC1N 3BG, UK.,UK Dementia Research Institute, University College London, London, WC1E 6BT, UK
| | - Elena R Rhymes
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.,UCL Queen Square Motor Neuron Disease Centre, University College London, London, WC1N 3BG, UK
| | - Stephen D Cahalan
- Comparative Neuromuscular Disease Laboratory, Department of Clinical Sciences and Services, Royal Veterinary College, University of London, London, NW1 0TU, UK
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK. .,UCL Queen Square Motor Neuron Disease Centre, University College London, London, WC1N 3BG, UK. .,UK Dementia Research Institute, University College London, London, WC1E 6BT, UK.
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6
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Zhu Z, Fang C, Xu H, Yuan L, Du Y, Ni Y, Xu Y, Shao A, Zhang A, Lou M. Anoikis resistance in diffuse glioma: The potential therapeutic targets in the future. Front Oncol 2022; 12:976557. [PMID: 36046036 PMCID: PMC9423707 DOI: 10.3389/fonc.2022.976557] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 07/25/2022] [Indexed: 11/28/2022] Open
Abstract
Glioma is the most common malignant intracranial tumor and exhibits diffuse metastasis and a high recurrence rate. The invasive property of glioma results from cell detachment. Anoikis is a special form of apoptosis that is activated upon cell detachment. Resistance to anoikis has proven to be a protumor factor. Therefore, it is suggested that anoikis resistance commonly occurs in glioma and promotes diffuse invasion. Several factors, such as integrin, E-cadherin, EGFR, IGFR, Trk, TGF-β, the Hippo pathway, NF-κB, eEF-2 kinase, MOB2, hypoxia, acidosis, ROS, Hsp and protective autophagy, have been shown to induce anoikis resistance in glioma. In our present review, we aim to summarize the underlying mechanism of resistance and the therapeutic potential of these molecules.
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Affiliation(s)
- Zhengyang Zhu
- Department of Neurosurgery, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chaoyou Fang
- Department of Neurosurgery, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Houshi Xu
- Department of Neurosurgery, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ling Yuan
- Department of Neurosurgery, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yichao Du
- Department of Neurosurgery, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yunjia Ni
- Department of Neurosurgery, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yuanzhi Xu
- Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Anwen Shao
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Department of Neurosurgery, Clinical Research Center for Neurological Diseases of Zhejiang Province, Hangzhou, China
| | - Anke Zhang
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Department of Neurosurgery, Clinical Research Center for Neurological Diseases of Zhejiang Province, Hangzhou, China
| | - Meiqing Lou
- Department of Neurosurgery, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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7
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Solé-Morata N, Baenas I, Etxandi M, Granero R, Forcales SV, Gené M, Barrot C, Gómez-Peña M, Menchón JM, Ramoz N, Gorwood P, Fernández-Aranda F, Jiménez-Murcia S. The role of neurotrophin genes involved in the vulnerability to gambling disorder. Sci Rep 2022; 12:6925. [PMID: 35484167 PMCID: PMC9051155 DOI: 10.1038/s41598-022-10391-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 04/07/2022] [Indexed: 01/16/2023] Open
Abstract
Evidence about the involvement of genetic factors in the development of gambling disorder (GD) has been assessed. Among studies assessing heritability and biological vulnerability for GD, neurotrophin (NTF) genes have emerged as promising targets, since a growing literature showed a possible link between NTF and addiction-related disorders. Thus, we aimed to explore the role of NTF genes and GD with the hypothesis that some NTF gene polymorphisms could constitute biological risk factors. The sample included 166 patients with GD and 191 healthy controls. 36 single nucleotide polymorphisms (SNPs) from NTFs (NGF, NGFR, NTRK1, BDNF, NTRK2, NTF3, NTRK3, NTF4, CNTF and CNTFR) were selected and genotyped. Linkage disequilibrium (LD) and haplotype constructions were analyzed, in relationship with the presence of GD. Finally, regulatory elements overlapping the identified SNPs variants associated with GD were searched. The between groups comparisons of allele frequencies indicated that 6 SNPs were potentially associated with GD. Single and multiple-marker analyses showed a strong association between both NTF3 and NTRK2 genes, and GD. The present study supports the involvement of the NTF family in the aetiopathogenesis of GD. An altered cross-regulation of different NTF members signalling pathways might be considered as a biological vulnerability factor for GD.
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Affiliation(s)
- Neus Solé-Morata
- Department of Psychiatry, Bellvitge University Hospital, c/Feixa Llarga S/N, Hospitalet de Llobregat, 08907, Barcelona, Spain
| | - Isabel Baenas
- Department of Psychiatry, Bellvitge University Hospital, c/Feixa Llarga S/N, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Psychoneurobiology of Eating and Addictive Behaviors Group, Neurosciences Program, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat, Spain.,Ciber Physiopathology of Obesity and Nutrition (CIBERObn), Instituto de Salud Carlos III, Barcelona, Spain
| | - Mikel Etxandi
- Department of Psychiatry, Bellvitge University Hospital, c/Feixa Llarga S/N, Hospitalet de Llobregat, 08907, Barcelona, Spain
| | - Roser Granero
- Psychoneurobiology of Eating and Addictive Behaviors Group, Neurosciences Program, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat, Spain.,Ciber Physiopathology of Obesity and Nutrition (CIBERObn), Instituto de Salud Carlos III, Barcelona, Spain.,Department of Psychobiology and Methodology, Autonomous University of Barcelona, Bellaterra, Spain
| | - Sonia V Forcales
- Serra Húnter Programme, Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, University of Barcelona, Hospitalet de Llobregat, 08907, Spain
| | - Manel Gené
- Genetic Lab, Forensic and Legal Medicine Unit, Department of Clinical Sciences, School of Medicine and Health Sciences, University of Barcelona, Barcelona, Spain
| | - Carme Barrot
- Genetic Lab, Forensic and Legal Medicine Unit, Department of Clinical Sciences, School of Medicine and Health Sciences, University of Barcelona, Barcelona, Spain
| | - Mónica Gómez-Peña
- Department of Psychiatry, Bellvitge University Hospital, c/Feixa Llarga S/N, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Psychoneurobiology of Eating and Addictive Behaviors Group, Neurosciences Program, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat, Spain
| | - José M Menchón
- Department of Psychiatry, Bellvitge University Hospital, c/Feixa Llarga S/N, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Department of Clinical Sciences, School of Medicine and Health Sciences, University of Barcelona, Hospitalet del Llobregat, Spain.,Ciber of Mental Health (CIBERSAM), Instituto de Salud Carlos III, Barcelona, Spain.,Psychiatry and Mental Health Group, Neuroscience Program, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet del Llobregat, Spain
| | - Nicolás Ramoz
- Psychiatry and Mental Health Group, Neuroscience Program, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet del Llobregat, Spain.,Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Team Vulnerability of Psychiatric and Addictive Disorders, Université de Paris, 75014, Paris, France
| | - Philip Gorwood
- Psychiatry and Mental Health Group, Neuroscience Program, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet del Llobregat, Spain.,Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Team Vulnerability of Psychiatric and Addictive Disorders, Université de Paris, 75014, Paris, France
| | - Fernando Fernández-Aranda
- Department of Psychiatry, Bellvitge University Hospital, c/Feixa Llarga S/N, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Psychoneurobiology of Eating and Addictive Behaviors Group, Neurosciences Program, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat, Spain.,Ciber Physiopathology of Obesity and Nutrition (CIBERObn), Instituto de Salud Carlos III, Barcelona, Spain.,Department of Clinical Sciences, School of Medicine and Health Sciences, University of Barcelona, Hospitalet del Llobregat, Spain
| | - Susana Jiménez-Murcia
- Department of Psychiatry, Bellvitge University Hospital, c/Feixa Llarga S/N, Hospitalet de Llobregat, 08907, Barcelona, Spain. .,Psychoneurobiology of Eating and Addictive Behaviors Group, Neurosciences Program, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat, Spain. .,Ciber Physiopathology of Obesity and Nutrition (CIBERObn), Instituto de Salud Carlos III, Barcelona, Spain. .,Department of Clinical Sciences, School of Medicine and Health Sciences, University of Barcelona, Hospitalet del Llobregat, Spain.
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8
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Role of Glycans on Key Cell Surface Receptors That Regulate Cell Proliferation and Cell Death. Cells 2021; 10:cells10051252. [PMID: 34069424 PMCID: PMC8159107 DOI: 10.3390/cells10051252] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/13/2021] [Accepted: 05/13/2021] [Indexed: 12/12/2022] Open
Abstract
Cells undergo proliferation and apoptosis, migration and differentiation via a number of cell surface receptors, most of which are heavily glycosylated. This review discusses receptor glycosylation and the known roles of glycans on the functions of receptors expressed in diverse cell types. We included growth factor receptors that have an intracellular tyrosine kinase domain, growth factor receptors that have a serine/threonine kinase domain, and cell-death-inducing receptors. N- and O-glycans have a wide range of functions including roles in receptor conformation, ligand binding, oligomerization, and activation of signaling cascades. A better understanding of these functions will enable control of cell survival and cell death in diseases such as cancer and in immune responses.
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9
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Zahavi EE, Hummel JJA, Han Y, Bar C, Stucchi R, Altelaar M, Hoogenraad CC. Combined kinesin-1 and kinesin-3 activity drives axonal trafficking of TrkB receptors in Rab6 carriers. Dev Cell 2021; 56:494-508.e7. [PMID: 33571451 PMCID: PMC7907685 DOI: 10.1016/j.devcel.2021.01.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 10/18/2020] [Accepted: 01/19/2021] [Indexed: 12/24/2022]
Abstract
Neurons depend on proper localization of neurotrophic receptors in their distal processes for their function. The Trk family of neurotrophin receptors controls neuronal survival, differentiation, and remodeling and are well known to function as retrograde signal carriers transported from the distal axon toward the cell body. However, the mechanism driving anterograde trafficking of Trk receptors into the axon is not well established. We used microfluidic compartmental devices and inducible secretion assay to systematically investigate the retrograde and anterograde trafficking routes of TrkB receptor along the axon in rat hippocampal neurons. We show that newly synthesized TrkB receptors traffic through the secretory pathway and are directly delivered into axon. We found that these TrkB carriers associate and are regulated by Rab6. Furthermore, the combined activity of kinesin-1 and kinesin-3 is needed for the formation of axon-bound TrkB secretory carriers and their effective entry and processive anterograde transport beyond the proximal axon.
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Affiliation(s)
- Eitan Erez Zahavi
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Jessica J A Hummel
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Yuhao Han
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Citlali Bar
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Riccardo Stucchi
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands; Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 Utrecht, the Netherlands
| | - Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 Utrecht, the Netherlands
| | - Casper C Hoogenraad
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands; Department of Neuroscience, Genentech, Inc., South San Francisco, CA 94080, USA.
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10
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Fleury S, Boukhatem I, Le Blanc J, Welman M, Lordkipanidzé M. Tissue-Specificity of Antibodies Raised Against TrkB and p75 NTR Receptors; Implications for Platelets as Models of Neurodegenerative Diseases. Front Immunol 2021; 12:606861. [PMID: 33643311 PMCID: PMC7905091 DOI: 10.3389/fimmu.2021.606861] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 01/04/2021] [Indexed: 11/13/2022] Open
Abstract
Platelets and neurons share many similarities including comparable secretory granule types with homologous calcium-dependent secretory mechanisms as well as internalization, sequestration and secretion of many neurotransmitters. Thus, platelets present a high potential to be used as peripheral biomarkers to reflect neuronal pathologies. The brain-derived neurotrophic factor (BDNF) acts as a neuronal growth factor involved in learning and memory through the binding of two receptors, the tropomyosin receptor kinase B (TrkB) and the 75 kDa pan-neurotrophic receptor (p75NTR). In addition to its expression in the central nervous system, BDNF is found in much greater quantities in blood circulation, where it is largely stored within platelets. Levels 100- to 1,000-fold those of neurons make platelets the most important peripheral reservoir of BDNF. This led us to hypothesize that platelets would express canonical BDNF receptors, i.e., TrkB and p75NTR, and that the receptors on platelets would bear significant resemblance to the ones found in the brain. However, herein we report discrepancies regarding detection of these receptors using antibody-based assays, with antibodies displaying important tissue-specificity. The currently available antibodies raised against TrkB and p75NTR should therefore be used with caution to study platelets as models for neurological disorders. Rigorous characterization of antibodies and bioassays appears critical to understand the interplay between platelet and neuronal biology of BDNF.
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Affiliation(s)
- Samuel Fleury
- Research Center, Montreal Heart Institute, Montreal, QC, Canada.,Faculty of Pharmacy, Université de Montréal, Montreal, QC, Canada
| | - Imane Boukhatem
- Research Center, Montreal Heart Institute, Montreal, QC, Canada.,Faculty of Pharmacy, Université de Montréal, Montreal, QC, Canada
| | - Jessica Le Blanc
- Research Center, Montreal Heart Institute, Montreal, QC, Canada.,Faculty of Pharmacy, Université de Montréal, Montreal, QC, Canada
| | - Mélanie Welman
- Research Center, Montreal Heart Institute, Montreal, QC, Canada
| | - Marie Lordkipanidzé
- Research Center, Montreal Heart Institute, Montreal, QC, Canada.,Faculty of Pharmacy, Université de Montréal, Montreal, QC, Canada
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11
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Regulation of BDNF-TrkB Signaling and Potential Therapeutic Strategies for Parkinson's Disease. J Clin Med 2020; 9:jcm9010257. [PMID: 31963575 PMCID: PMC7019526 DOI: 10.3390/jcm9010257] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 12/19/2019] [Accepted: 01/15/2020] [Indexed: 12/20/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase receptor type B (TrkB) are widely distributed in multiple regions of the human brain. Specifically, BDNF/TrkB is highly expressed and activated in the dopaminergic neurons of the substantia nigra and plays a critical role in neurophysiological processes, including neuro-protection and maturation and maintenance of neurons. The activation as well as dysfunction of the BDNF-TrkB pathway are associated with neurodegenerative diseases. The expression of BDNF/TrkB in the substantia nigra is significantly reduced in Parkinson's Disease (PD) patients. This review summarizes recent progress in the understanding of the cellular and molecular roles of BNDF/TrkB signaling and its isoform, TrkB.T1, in Parkinson's disease. We have also discussed the effects of current therapies on BDNF/TrkB signaling in Parkinson's disease patients and the mechanisms underlying the mutation-mediated acquisition of resistance to therapies for Parkinson's disease.
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Shen J, Sun D, Shao J, Chen Y, Pang K, Guo W, Lu B. Extracellular Juxtamembrane Motif Critical for TrkB Preformed Dimer and Activation. Cells 2019; 8:cells8080932. [PMID: 31430955 PMCID: PMC6721692 DOI: 10.3390/cells8080932] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 08/15/2019] [Accepted: 08/15/2019] [Indexed: 01/12/2023] Open
Abstract
Receptor tyrosine kinases are believed to be activated through ligand-induced dimerization. We now demonstrate that in cultured neurons, a substantial amount of endogenous TrkB, the receptor for brain-derived neurotrophic factor (BDNF), exists as an inactive preformed dimer, and the application of BDNF activates the pre-existing dimer. Deletion of the extracellular juxtamembrane motif (EJM) of TrkB increased the amount of preformed dimer, suggesting an inhibitory role of EJM on dimer formation. Further, binding of an agonistic antibody (MM12) specific to human TrkB-EJM activated the full-length TrkB and unexpectedly also truncated TrkB lacking ECD (TrkBdelECD365), suggesting that TrkB is activated by attenuating the inhibitory effect of EJM through MM12 binding-induced conformational changes. Finally, in cells co-expressing rat and human TrkB, MM12 could only activate TrkB human-human dimer but not TrkB human-rat TrkB dimer, indicating that MM12 binding to two TrkB monomers is required for activation. Our results support a model that TrkB preforms as an inactive dimer and BDNF induces TrkB conformation changes leading to its activation.
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Affiliation(s)
- Jianying Shen
- School of Pharmaceutical Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
- Artemisinin Research Center, Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100084, China
| | - Dang Sun
- School of Pharmaceutical Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
| | - Jingyu Shao
- School of Pharmaceutical Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
| | - Yanbo Chen
- School of Pharmaceutical Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
| | - Keliang Pang
- School of Pharmaceutical Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
| | - Wei Guo
- School of Pharmaceutical Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
- R & D Center for the Diagnosis and Treatment of Major Brain Diseases, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
| | - Bai Lu
- School of Pharmaceutical Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China.
- R & D Center for the Diagnosis and Treatment of Major Brain Diseases, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China.
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Otani K, Okada M, Yamawaki H. Diverse distribution of tyrosine receptor kinase B isoforms in rat multiple tissues. J Vet Med Sci 2017; 79:1516-1523. [PMID: 28757509 PMCID: PMC5627321 DOI: 10.1292/jvms.17-0257] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tyrosine receptor kinase B (TrkB), a receptor for brain-derived neurotrophic factor and neurotrophin-3, includes the alternatively spliced three isoforms specifically in rats. Each isoform, full length TrkB (TrkB FL), truncated TrkB type-1 (TrkB T1) and type-2 (TrkB T2), seems to mediate diverse cellular function. Some studies suggest that TrkB plays a key role in both neural and non-neural systems. In the present study, we examined mRNA and protein expression profile of three TrkB isoforms in normal adult rat multiple tissues. TrkB FL mRNA and protein were both highly expressed exclusively in brain. While TrkB T1 mRNA was highly expressed exclusively in brain, glycosylated TrkB T1 protein was expressed in brain and heart. TrkB T2 mRNA level in brain was the highest. In brain, TrkB FL mRNA expression was higher in cerebral cortex, but lower in brainstem. TrkB T1 mRNA expression was higher in hypothalamus, but lower in cerebellum. TrkB T2 mRNA expression was higher in cerebral cortex and cerebellum, but lower in brainstem. The present study for the first time clarified diverse distribution of three TrkB isoforms in rat multiple tissues and could serve as a useful resource for understanding the physiology and pathophysiology of mammals including human via comparing the expression pattern of TrkB isoforms.
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Affiliation(s)
- Kosuke Otani
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 bancho 35-1, Towada, Aomori 034-8628, Japan
| | - Muneyoshi Okada
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 bancho 35-1, Towada, Aomori 034-8628, Japan
| | - Hideyuki Yamawaki
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 bancho 35-1, Towada, Aomori 034-8628, Japan
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Normal Molecular Specification and Neurodegenerative Disease-Like Death of Spinal Neurons Lacking the SNARE-Associated Synaptic Protein Munc18-1. J Neurosci 2016; 36:561-76. [PMID: 26758845 DOI: 10.1523/jneurosci.1964-15.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED The role of synaptic activity during early formation of neural circuits is a topic of some debate; genetic ablation of neurotransmitter release by deletion of the Munc18-1 gene provides an excellent model to answer the question of whether such activity is required for early circuit formation. Previous analysis of Munc18-1(-/-) mouse mutants documented their grossly normal nervous system, but its molecular differentiation has not been assessed. Munc18-1 deletion in mice also results in widespread neurodegeneration that remains poorly characterized. In this study, we demonstrate that the early stages of spinal motor circuit formation, including motor neuron specification, axon growth and pathfinding, and mRNA expression, are unaffected in Munc18-1(-/-) mice, demonstrating that synaptic activity is dispensable for early nervous system development. Furthermore, we show that the neurodegeneration caused by Munc18-1 loss is cell autonomous, consistent with apparently normal expression of several neurotrophic factors and normal GDNF signaling. Consistent with cell-autonomous degeneration, we demonstrate defects in the trafficking of the synaptic proteins Syntaxin1a and PSD-95 and the TrkB and DCC receptors in Munc18-1(-/-) neurons; these defects do not appear to cause ER stress, suggesting other mechanisms for degeneration. Finally, we demonstrate pathological similarities to Alzheimer's disease, such as altered Tau phosphorylation, neurofibrillary tangles, and accumulation of insoluble protein plaques. Together, our results shed new light upon the neurodegeneration observed in Munc18-1(-/-) mice and argue that this phenomenon shares parallels with neurodegenerative diseases. SIGNIFICANCE STATEMENT In this work, we demonstrate the absence of a requirement for regulated neurotransmitter release in the assembly of early neuronal circuits by assaying transcriptional identity, axon growth and guidance, and mRNA expression in Munc18-1-null mice. Furthermore, we characterize the neurodegeneration observed in Munc18-1 mutants and demonstrate that this cell-autonomous process does not appear to be a result of defects in growth factor signaling or ER stress caused by protein trafficking defects. However, we find the presence of various pathological hallmarks of Alzheimer's disease that suggest parallels between the degeneration in these mutants and neurodegenerative conditions.
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15
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Exploring the Molecular Interactions of 7,8-Dihydroxyflavone and Its Derivatives with TrkB and VEGFR2 Proteins. Int J Mol Sci 2015; 16:21087-108. [PMID: 26404256 PMCID: PMC4613243 DOI: 10.3390/ijms160921087] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 08/21/2015] [Accepted: 08/26/2015] [Indexed: 11/16/2022] Open
Abstract
7,8-dihydroxyflavone (7,8-DHF) is a TrkB receptor agonist, and treatment with this flavonoid derivative brings about an enhanced TrkB phosphorylation and promotes downstream cellular signalling. Flavonoids are also known to exert an inhibitory effect on the vascular endothelial growth factor receptor (VEGFR) family of tyrosine kinase receptors. VEGFR2 is one of the important receptors involved in the regulation of vasculogenesis and angiogenesis and has also been implicated to exhibit various neuroprotective roles. Its upregulation and uncontrolled activity is associated with a range of pathological conditions such as age-related macular degeneration and various proliferative disorders. In this study, we investigated molecular interactions of 7,8-DHF and its derivatives with both the TrkB receptor as well as VEGFR2. Using a combination of molecular docking and computational mapping tools involving molecular dynamics approaches we have elucidated additional residues and binding energies involved in 7,8-DHF interactions with the TrkB Ig2 domain and VEGFR2. Our investigations have revealed for the first time that 7,8-DHF has dual biochemical action and its treatment may have divergent effects on the TrkB via its extracellular Ig2 domain and on the VEGFR2 receptor through the intracellular kinase domain. Contrary to its agonistic effects on the TrkB receptor, 7,8-DHF was found to downregulate VEGFR2 phosphorylation both in 661W photoreceptor cells and in retinal tissue.
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Liu X, Obianyo O, Chan CB, Huang J, Xue S, Yang JJ, Zeng F, Goodman M, Ye K. Biochemical and biophysical investigation of the brain-derived neurotrophic factor mimetic 7,8-dihydroxyflavone in the binding and activation of the TrkB receptor. J Biol Chem 2014; 289:27571-84. [PMID: 25143381 DOI: 10.1074/jbc.m114.562561] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
7,8-dihydroxyflavone (7,8-DHF), a newly identified small molecular TrkB receptor agonist, rapidly activates TrkB in both primary neurons and the rodent brain and mimics the physiological functions of the cognate ligand BDNF. Accumulating evidence supports that 7,8-DHF exerts neurotrophic effects in a TrkB-dependent manner. Nonetheless, the differences between 7,8-DHF and BDNF in activating TrkB remain incompletely understood. Here we show that 7,8-DHF and BDNF exhibit different TrkB activation kinetics in which TrkB maturation may be implicated. Employing two independent biophysical approaches, we confirm that 7,8-DHF interacts robustly with the TrkB extracellular domain, with a Kd of ∼10 nm. Although BDNF transiently activates TrkB, leading to receptor internalization and ubiquitination/degradation, in contrast, 7,8-DHF-triggered TrkB phosphorylation lasts for hours, and the internalized receptors are not degraded. Notably, primary neuronal maturation may be required for 7,8-DHF but not for BDNF to elicit the full spectrum of TrkB signaling cascades. Hence, 7,8-DHF interacts robustly with the TrkB receptor, and its agonistic effect may be mediated by neuronal development and maturation.
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Affiliation(s)
- Xia Liu
- From the Departments of Pathology and Laboratory Medicine and
| | | | - Chi Bun Chan
- From the Departments of Pathology and Laboratory Medicine and
| | - Junjian Huang
- From the Departments of Pathology and Laboratory Medicine and
| | - Shenghui Xue
- the Departments of Chemistry and Biology, Center for Diagnostics and Therapeutics (CDT), Georgia State University, Atlanta, Georgia 30303
| | - Jenny J Yang
- the Departments of Chemistry and Biology, Center for Diagnostics and Therapeutics (CDT), Georgia State University, Atlanta, Georgia 30303
| | - Fanxing Zeng
- Radiology and Imaging Sciences, Psychiatry, and Hematology and Oncology, Center for Systems Imaging, Wesley Woods Health Centers, Emory University School of Medicine, Atlanta, Georgia 30322 and
| | - Mark Goodman
- Radiology and Imaging Sciences, Psychiatry, and Hematology and Oncology, Center for Systems Imaging, Wesley Woods Health Centers, Emory University School of Medicine, Atlanta, Georgia 30322 and
| | - Keqiang Ye
- From the Departments of Pathology and Laboratory Medicine and
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Impairments in Brain-Derived Neurotrophic Factor-Induced Glutamate Release in Cultured Cortical Neurons Derived from Rats with Intrauterine Growth Retardation: Possible Involvement of Suppression of TrkB/Phospholipase C-γ Activation. Neurochem Res 2014; 39:785-92. [DOI: 10.1007/s11064-014-1270-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 02/10/2014] [Accepted: 02/25/2014] [Indexed: 10/25/2022]
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18
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Fenner BM. Truncated TrkB: beyond a dominant negative receptor. Cytokine Growth Factor Rev 2012; 23:15-24. [PMID: 22341689 DOI: 10.1016/j.cytogfr.2012.01.002] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 01/13/2012] [Indexed: 12/14/2022]
Abstract
BDNF activates trkB receptors to regulate neuronal survival, differentiation, and proliferation. Mutations in the BDNF gene, altered BDNF expression, and altered trkB expression are associated with degenerative and psychiatric disorders. The full-length trkB receptor (trkB.tk(+)) undergoes autophosphorylation to activate intracellular signaling pathways. The truncated trkB receptor (trkB.t1) is abundantly expressed in the brain but lacks the catalytic tyrosine kinase domain. TrkB.t1 is a dominant-negative receptor that inhibits trkB.tk(+) signaling. While this is an important function of trkB.t1, it is only one of its many functions. TrkB.t1 sequesters and translocate BDNF, induces filopodia and neurite outgrowth, stimulates intracellular signaling cascades, regulates Rho GTPase signaling, and modifies cytoskeletal structures. TrkB.t1 is an active signaling molecule with regulatory effects on neurons and astrocytes.
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Li T, Talvenheimo J, Zeni L, Rosenfeld R, Stearns G, Arakawa T. Changes in protein conformation and dynamics upon complex formation of brain-derived neurotrophic factor and its receptor: investigation by isotope-edited Fourier transform IR spectroscopy. Biopolymers 2002; 67:10-9. [PMID: 11842409 DOI: 10.1002/bip.10038] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The interactions of brain-derived neurotrophic factor (BDNF) with the extracellular domain of its receptor (trkB) are investigated by employing isotope-edited Fourier transform IR (FTIR) spectroscopy. The protein secondary structures of individual BDNF and trkB in solutions are compared with those in their complex. The temperature dependence of the secondary structures of BDNF, trkB, and their complex is also investigated. Consistent with the crystal structure, we observe by FTIR spectroscopy that BDNF in solution contains predominantly beta strands (approximately 53%) and relatively low contents of other secondary structures including beta turns (approximately 16%), disordered structures (approximately 12%), and loops (approximately 18%) and is deficient in alpha helix. We also observe that trkB in solution contains mostly beta strands (52%) and little alpha helix. Conformational changes in both BDNF and trkB are observed upon complex formation. Specifically, upon binding of BDNF, the conformational changes in trkB appear to involve mostly beta turns and disordered structures while the majority of the beta-strand conformation remains unchanged. The IR data indicate that some of the disordered structures in the loop regions are likely converted to beta strands upon complex formation. The FTIR spectral data of BDNF, trkB, and their complex indicate that more amide NH groups of trkB undergo H-D exchange within the complex than those of the ligand-free receptor and that the thermal stability of trkB is decreased slightly upon binding of BDNF. The FT-Raman spectra of BDNF, trkB, and their complex show that the six intramolecular disulfide bonds of trkB undergo significant conformational changes upon binding of BDNF as a result of changes in the tertiary structure of trkB. Taken together, the FTIR and Raman data are consistent with the loosening of the tertiary structure of trkB upon binding of BDNF, which leads to more solvent exposure of the amide NH group and decreased thermal stability of trkB. This finding reveals an intriguing structural property of the neurotrophin ligand-receptor complex that is in contrast to other ligand-receptor complexes such as a cytokine-receptor complex that usually shows protection of the amide NH group and increased thermal stability upon complex formation.
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Affiliation(s)
- Tiansheng Li
- Department of Pharmaceutics, Amgen Inc., Amgen Center, M/S 8-1-C, One Amgen Boulevard, Thousand Oaks, California 91320, USA.
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20
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Kojima S, Nakayama T, Kuwajima G, Suzuki H, Sakata T. TrkB mutant lacking the amino-terminal half of the extracellular portion acts as a functional brain-derived neurotrophic factor receptor. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1420:104-10. [PMID: 10446295 DOI: 10.1016/s0005-2736(99)00094-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
A series of mutants with deletion in the extracellular portion of TrkB were expressed transiently and stably in mammalian cells to examine the brain-derived neurotrophic factor (BDNF)-binding properties of TrkB. We found that these binding activities were retained by the TrkB deletion mutant (TrkBDelta4) lacking most of the extracellular portion, cysteine-rich cluster 1 and 2, leucine-rich motif and most of the first immunoglobulin-like domain (Ig1). Furthermore, the results of the neurotrophin selectivity, the equilibrium binding constant, auto-phosphorylation and BDNF dependent cell survival indicate that TrkBDelta4 acts as a functional BDNF receptor comparable to wild-type TrkB. Thus, our findings showed that only the carboxyl-terminal half of the extracellular portion of TrkB, which includes the Ig2 domain, is essential for the functional BDNF receptor.
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Affiliation(s)
- S Kojima
- Shionogi Institute for Medical Science, 2-5-1, Mishima, Settsu-shi, Osaka 566-0022, Japan
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21
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Subcellular localization of full-length and truncated Trk receptor isoforms in polarized neurons and epithelial cells. J Neurosci 1999. [PMID: 10407023 DOI: 10.1523/jneurosci.19-14-05823.1999] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neurotrophins affect neuronal development and plasticity via spatially localized effects, yet little is known about the subcellular distribution of the Trk neurotrophin receptors and the impact of this distribution on neurotrophin action. To address this, we examined the subcellular location of full-length TrkB and TrkC tyrosine kinase receptors and truncated TrkB isoforms after transfection of Madin-Darby canine kidney (MDCK) cells, dissociated primary hippocampal neurons, and cortical neurons within intact brain slices. Myc-, herpes virus glycoprotein (HVG)-, or FLAG-derived epitope-tagged receptor isoforms were created to allow their unambiguous identification and localization after transfection. All tagged receptors were appropriately synthesized, and full-length myc-TrkB and myc-TrkC mediated appropriate neurotrophin-signaling events. We found that full-length TrkB receptors were excluded from the apical domain of MDCK cells but that TrkC receptors were present in both apical and basolateral domains. Full-length TrkB and TrkC were found throughout transfected primary cultured hippocampal neurons and transfected neurons in neocortical brain slices and showed no evidence of vectorial sorting. Truncated forms of TrkB were also homogeneously distributed in MDCK cells, dissociated hippocampal neurons, and cortical neurons within slice preparations. Levels of full-length and truncated TrkB were examined in postsynaptic densities; both receptor isoforms were present but only moderately enriched in these structures. Together, these findings suggest that Trk receptors are uniformly distributed in both axonal and dendritic compartments and that local neurotrophin responses are controlled by other mechanisms.
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Haniu M, Montestruque S, Bures EJ, Talvenheimo J, Toso R, Lewis-Sandy S, Welcher AA, Rohde MF. Interactions between brain-derived neurotrophic factor and the TRKB receptor. Identification of two ligand binding domains in soluble TRKB by affinity separation and chemical cross-linking. J Biol Chem 1997; 272:25296-303. [PMID: 9312147 DOI: 10.1074/jbc.272.40.25296] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The extracellular domain of the human neurotrophin TRKB receptor expressed in Chinese hamster ovary cells is a highly glycosylated protein, possessing binding ability for brain-derived neurotrophic factor (BDNF). Two distinct ligand binding domains of TRKB were isolated from proteolytic digests of the receptor by affinity separation on immobilized BDNF. One of these domains consists of amino acid residues 103-181 and contains both the third leucine-rich motif and the second cysteine cluster domain. The second domain is close to the second immunoglobulin-like domain (amino acid residues 342-394). Each of these two domains can bind BDNF independently. Disulfide linkages present in the first domain are necessary for BDNF binding, probably because of preservation of the native conformation. To study the second domain in greater detail, a truncated form of TRKB containing the second immunoglobulin-like domain (residues 248-398) was expressed in Escherichia coli. This domain was cross-linked to BDNF through a 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide coupling reaction. Several synthetic peptides corresponding to amino acid residues 343-379 were able to bind immobilized BDNF. Amino acid substitution and cross-linking analysis indicated that amino acids Phe347, Asp354, and Tyr361 are intimately involved in BDNF binding. These results, obtained from a variety of experimental techniques, highlight the importance of two distinct regions of the extracellular domain of the TRKB receptor in binding BDNF.
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Affiliation(s)
- M Haniu
- Departments of Protein Structure, Protein Chemistry, and Immunology, Amgen, Inc., Thousand Oaks, California 91320, USA. mhaniu@amgen
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23
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Ninkina N, Grashchuck M, Buchman VL, Davies AM. TrkB variants with deletions in the leucine-rich motifs of the extracellular domain. J Biol Chem 1997; 272:13019-25. [PMID: 9148911 DOI: 10.1074/jbc.272.20.13019] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We have isolated two novel variants involving the extracellular domain of TrkB from developing sensory neurons. These variants are generated by alternative splicing and lack two or all three of the leucine-rich motifs. Each of these variants is expressed as isoforms that possess or lack the intracellular tyrosine kinase domain. Fibroblast cell lines stably expressing these variants do not bind any of the TrkB ligands (brain-derived neurotrophic factor, neurotrophin-3, and neurotrophin-4/5) and neither survive nor undergo morphological transformation in response to neurotrophins. These results demonstrate that the leucine-rich motifs in TrkB are essential for ligand binding and signaling and indicate that the extracellular immunoglobulin-like domains alone are insufficient to confer neurotrophin binding to TrkB.
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Affiliation(s)
- N Ninkina
- School of Biological and Medical Sciences, University of St. Andrews, St. Andrews, Fife KY16 9AJ, Scotland
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