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Holzner C, Böttinger K, Blöchl C, Huber CG, Dahms SO, Dall E, Brandstetter H. Legumain Functions as a Transient TrkB Sheddase. Int J Mol Sci 2023; 24:ijms24065394. [PMID: 36982466 PMCID: PMC10049731 DOI: 10.3390/ijms24065394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 03/07/2023] [Accepted: 03/09/2023] [Indexed: 03/14/2023] Open
Abstract
While primarily found in endo-lysosomal compartments, the cysteine protease legumain can also translocate to the cell surface if stabilized by the interaction with the RGD-dependent integrin receptor αVβ3. Previously, it has been shown that legumain expression is inversely related to BDNF-TrkB activity. Here we show that legumain can conversely act on TrkB-BDNF by processing the C-terminal linker region of the TrkB ectodomain in vitro. Importantly, when in complex with BDNF, TrkB was not cleaved by legumain. Legumain-processed TrkB was still able to bind BDNF, suggesting a potential scavenger function of soluble TrkB towards BDNF. The work thus presents another mechanistic link explaining the reciprocal TrkB signaling and δ-secretase activity of legumain, with relevance for neurodegeneration.
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2
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Sulimai N, Lominadze D. Fibrinogen and Neuroinflammation During Traumatic Brain Injury. Mol Neurobiol 2020; 57:4692-4703. [PMID: 32776201 DOI: 10.1007/s12035-020-02012-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 07/08/2020] [Indexed: 12/14/2022]
Abstract
Many neurodegenerative diseases such as Alzheimer's disease (AD), multiple sclerosis, and traumatic brain injury (TBI) are associated with systemic inflammation. Inflammation itself results in increased blood content of fibrinogen (Fg), called hyperfibrinogenemia (HFg). Fg is not only considered an acute phase protein and a marker of inflammation, but has been shown that it can cause inflammatory responses. Fibrin deposits have been associated with memory reduction in neuroinflammatory diseases such as AD and TBI. Reduction in short-term memory has been seen during the most common form of TBI, mild-to-moderate TBI. Fibrin deposits have been found in brains of patients with mild-to-moderate TBI. The vast majority of the literature emphasizes the role of fibrin-activated microglia as the mediator in the neuroinflammation pathway. However, the recent discovery that astrocytes, which constitute approximately 30% of the cells in the mammalian central nervous system, manifest different reactive states warrants further investigations in the causative role of HFg in astrocyte-mediated neuroinflammation. Our previous study showed that Fg deposited in the vasculo-astrocyte interface-activated astrocytes. However, little is known of how Fg directly affects astrocytes and neurons. In this review, we summarize studies that show the effect of Fg on different types of cells in the vasculo-neuronal unit. We will also discuss the possible mechanism of HFg-induced neuroinflammation during TBI.
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Affiliation(s)
- Nurul Sulimai
- Departments of Surgery, University of South Florida Morsani College of Medicine, MDC-4024, 12901 Bruce B. Downs Blvd, Tampa, FL, 33612, USA
| | - David Lominadze
- Departments of Surgery, University of South Florida Morsani College of Medicine, MDC-4024, 12901 Bruce B. Downs Blvd, Tampa, FL, 33612, USA.
- Molecular Pharmacology and Physiology, University of South Florida Morsani College of Medicine, Tampa, FL, 33612, USA.
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3
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Polymeric nanoparticles decorated with BDNF-derived peptide for neuron-targeted delivery of PTEN inhibitor. Eur J Pharm Sci 2018; 124:37-45. [DOI: 10.1016/j.ejps.2018.08.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 08/05/2018] [Accepted: 08/16/2018] [Indexed: 01/15/2023]
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4
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Osborne A, Khatib TZ, Songra L, Barber AC, Hall K, Kong GYX, Widdowson PS, Martin KR. Neuroprotection of retinal ganglion cells by a novel gene therapy construct that achieves sustained enhancement of brain-derived neurotrophic factor/tropomyosin-related kinase receptor-B signaling. Cell Death Dis 2018; 9:1007. [PMID: 30258047 PMCID: PMC6158290 DOI: 10.1038/s41419-018-1041-8] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 09/04/2018] [Accepted: 09/07/2018] [Indexed: 01/17/2023]
Abstract
Previous studies have demonstrated that intravitreal delivery of brain-derived neurotrophic factor (BDNF) by injection of recombinant protein or by gene therapy can alleviate retinal ganglion cell (RGC) loss after optic nerve injury. BDNF gene therapy can improve RGC survival in experimental models of glaucoma, the leading cause of irreversible blindness worldwide. However, the therapeutic efficacy of BDNF supplementation alone is time limited at least in part due to BDNF receptor downregulation. Tropomyosin-related receptor kinase-B (TrkB) downregulation has been reported in many neurological diseases including glaucoma, potentially limiting the effect of sustained or repeated BDNF delivery. Here, we characterize a novel adeno-associated virus (AAV) gene therapy (AAV2 TrkB-2A-mBDNF) that not only increases BDNF production but also improves long-term neuroprotective signaling by increasing expression of the BDNF receptor (TrkB) within the inner retina. This approach leads to significant and sustained elevation of survival signaling pathways ERK and AKT within RGCs over 6 months and avoids the receptor downregulation which we observe with treatment with AAV2 BDNF alone. We validate the neuroprotective efficacy of AAV2 TrkB-2A-mBDNF in a mouse model of optic nerve injury, where it outperforms conventional AAV2 BDNF or AAV2 TrkB therapy, before showing powerful proof of concept neuroprotection of RGCs and axons in a rat model of chronic intraocular pressure (IOP) elevation. We also show that there are no adverse effects of the vector on retinal structure or function as assessed by histology and electroretinography in young or aged animals. Further studies are underway to explore the potential of this vector as a candidate for progression into clinical studies to protect RGCs in patients with glaucoma and progressive visual loss despite conventional IOP-lowering treatment.
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Affiliation(s)
- Andrew Osborne
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,Quethera Ltd, Babraham Research Campus, Cambridge, UK
| | - Tasneem Z Khatib
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,Eye Department, Addenbrooke's Hospital, Cambridge, UK
| | - Lalana Songra
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Amanda C Barber
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Katie Hall
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - George Y X Kong
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Australia.,University of Melbourne, Melbourne, Australia
| | | | - Keith R Martin
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK. .,Quethera Ltd, Babraham Research Campus, Cambridge, UK. .,Eye Department, Addenbrooke's Hospital, Cambridge, UK. .,Cambridge NIHR Biomedical Research Centre, Cambridge, UK. .,Wellcome Trust-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK.
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5
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Butkovich LM, Houser MC, Tansey MG. α-Synuclein and Noradrenergic Modulation of Immune Cells in Parkinson's Disease Pathogenesis. Front Neurosci 2018; 12:626. [PMID: 30258347 PMCID: PMC6143806 DOI: 10.3389/fnins.2018.00626] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 08/21/2018] [Indexed: 12/29/2022] Open
Abstract
α-synuclein (α-syn) pathology and loss of noradrenergic neurons in the locus coeruleus (LC) are among the most ubiquitous features of Parkinson's disease (PD). While noradrenergic dysfunction is associated with non-motor symptoms of PD, preclinical research suggests that the loss of LC norepinephrine (NE), and subsequently its immune modulatory and neuroprotective actions, may exacerbate or even accelerate disease progression. In this review, we discuss the mechanisms by which α-syn pathology and loss of central NE may directly impact brain health by interrupting neurotrophic factor signaling, exacerbating neuroinflammation, and altering regulation of innate and adaptive immune cells.
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Affiliation(s)
| | | | - Malú G. Tansey
- Tansey Laboratory, Department of Physiology, School of Medicine, Emory University, Atlanta, GA, United States
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6
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Stagni F, Giacomini A, Guidi S, Emili M, Uguagliati B, Salvalai ME, Bortolotto V, Grilli M, Rimondini R, Bartesaghi R. A flavonoid agonist of the TrkB receptor for BDNF improves hippocampal neurogenesis and hippocampus-dependent memory in the Ts65Dn mouse model of DS. Exp Neurol 2017; 298:79-96. [DOI: 10.1016/j.expneurol.2017.08.018] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 08/24/2017] [Accepted: 08/31/2017] [Indexed: 12/31/2022]
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7
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Cho T, Ryu JK, Taghibiglou C, Ge Y, Chan AW, Liu L, Lu J, McLarnon JG, Wang YT. Long-term potentiation promotes proliferation/survival and neuronal differentiation of neural stem/progenitor cells. PLoS One 2013; 8:e76860. [PMID: 24146937 PMCID: PMC3798289 DOI: 10.1371/journal.pone.0076860] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 08/28/2013] [Indexed: 11/19/2022] Open
Abstract
Neural stem cell (NSC) replacement therapy is considered a promising cell replacement therapy for various neurodegenerative diseases. However, the low rate of NSC survival and neurogenesis currently limits its clinical potential. Here, we examined if hippocampal long-term potentiation (LTP), one of the most well characterized forms of synaptic plasticity, promotes neurogenesis by facilitating proliferation/survival and neuronal differentiation of NSCs. We found that the induction of hippocampal LTP significantly facilitates proliferation/survival and neuronal differentiation of both endogenous neural progenitor cells (NPCs) and exogenously transplanted NSCs in the hippocampus in rats. These effects were eliminated by preventing LTP induction by pharmacological blockade of the N-methyl-D-aspartate glutamate receptor (NMDAR) via systemic application of the receptor antagonist, 3-[(R)-2-carboxypiperazin-4-yl]-propyl-1-phosphonic acid (CPP). Moreover, using a NPC-neuron co-culture system, we were able to demonstrate that the LTP-promoted NPC neurogenesis is at least in part mediated by a LTP-increased neuronal release of brain-derived neurotrophic factor (BDNF) and its consequent activation of tropomysosin receptor kinase B (TrkB) receptors on NSCs. Our results indicate that LTP promotes the neurogenesis of both endogenous and exogenously transplanted NSCs in the brain. The study suggests that pre-conditioning of the host brain receiving area with a LTP-inducing deep brain stimulation protocol prior to NSC transplantation may increase the likelihood of success of using NSC transplantation as an effective cell therapy for various neurodegenerative diseases.
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Affiliation(s)
- Taesup Cho
- Brain Research Centre and Department of Medicine, University of British Columbia, Vancouver, Canada
| | - Jae K. Ryu
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Changiz Taghibiglou
- Brain Research Centre and Department of Medicine, University of British Columbia, Vancouver, Canada
| | - Yuan Ge
- Brain Research Centre and Department of Medicine, University of British Columbia, Vancouver, Canada
| | - Allen W. Chan
- Brain Research Centre and Department of Medicine, University of British Columbia, Vancouver, Canada
| | - Lidong Liu
- Brain Research Centre and Department of Medicine, University of British Columbia, Vancouver, Canada
| | - Jie Lu
- Brain Research Centre and Department of Medicine, University of British Columbia, Vancouver, Canada
| | - James G. McLarnon
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Yu Tian Wang
- Brain Research Centre and Department of Medicine, University of British Columbia, Vancouver, Canada
- Translational Medicine Research Center, China Medical University Hospital and Graduate Institute of Immunology, China Medical University, Taichung, Taiwan, Republic of China
- * E-mail:
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Verma A, Sharma DK, Sarma R, Chetia H, Saikia J. Comparative insights using the molecular homology model of BDNF (Brain derived neurotrophic factor) of Varanus komodoensis and the known NGF (Nerve growth factor) structure of Naja atra. Bioinformation 2013; 9:755-8. [PMID: 24023416 PMCID: PMC3766306 DOI: 10.6026/97320630009755] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 08/08/2013] [Indexed: 11/23/2022] Open
Abstract
BDNF (Brain derived neurotrophic factor) is a secretion protein and a member of the neurotrophin family of growth factors. Structural and functional characterization of BDNF Varanus komodoensis is of interest while its structure remains unknown. Thus, a homology molecular model of BDNF was constructed for gleaning possible structural insights. The model was compared with the structure of the homologous NGF (Nerve growth factor, another member of neuro-trophin family) from Naja atra. Comparative structural analysis of the models showed structural similarities with their predicted cavities for the interpretation of potential functional analogy.
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Affiliation(s)
- Ankit Verma
- Bioinformatics Infrastructure Facility, Gauhati University, Guwahati - 781014, Assam, India
| | - Dhirendra Kumar Sharma
- Bioinformatics Infrastructure Facility, Gauhati University, Guwahati - 781014, Assam, India
| | - Rituparna Sarma
- Bioinformatics Infrastructure Facility, Gauhati University, Guwahati - 781014, Assam, India
| | - Hasnahana Chetia
- Bioinformatics Infrastructure Facility, Gauhati University, Guwahati - 781014, Assam, India
| | - Juri Saikia
- Bioinformatics Infrastructure Facility, Gauhati University, Guwahati - 781014, Assam, India
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9
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Obianyo O, Ye K. Novel small molecule activators of the Trk family of receptor tyrosine kinases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1834:2213-8. [PMID: 22982231 DOI: 10.1016/j.bbapap.2012.08.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 08/29/2012] [Indexed: 12/18/2022]
Abstract
The Tropomyosin-related kinase (Trk) receptors are a subset of the receptor tyrosine kinase family with an important functionality in the regulation of neurotrophic signaling in the peripheral and central nervous system. As the receptors are able to mediate neuronal survival by associating with their respective neurotrophin ligands, many studies have focused on the therapeutic potential of generating small-molecule mimetic compounds that elicit agonistic effects similar to those of the natural protein ligands. To this end, various structure-based studies have led to the generation of bivalent peptide-based agonists and antibodies that selectively initiate Trk receptor signaling; however, these compounds do not possess the ideal characteristics of a potential drug. Additionally, the reliance of structure-based data to generate the compound libraries, limits the potential identification of novel chemical structures with desirable activity. Therefore, subsequent investigations utilized a cell-based apoptotic screen to facilitate the analysis of large, diverse chemical libraries of small molecules and quickly identify compounds with Trk-dependent anti-apoptotic activity. Herein, we describe the Trk agonists that have been identified by this screening methodology and summarize their in vitro and in vivo neurotrophic activity as well as their efficacy in various neurological disease models, implicating their future utility as therapeutic compounds. This article is part of a Special Issue entitled: Emerging recognition and activation mechanisms of receptor tyrosine kinases.
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Affiliation(s)
- Obiamaka Obianyo
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
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10
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Fabrication of growth factor- and extracellular matrix-loaded, gelatin-based scaffolds and their biocompatibility with Schwann cells and dorsal root ganglia. Biomaterials 2012; 33:8529-39. [PMID: 22906605 DOI: 10.1016/j.biomaterials.2012.07.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 07/15/2012] [Indexed: 12/11/2022]
Abstract
One of the most exciting new avenues of research to repair the injured spinal cord is to combine cells for implantation with scaffolds that protect the cells and release growth factors to improve their survival and promote host axonal regeneration. To realize this goal, we fabricated biodegradable, photocurable gelatin tubes and membranes for exploratory in vitro studies. Detailed methods are described for their fabrication with a high gelatin concentration. Gelatin membranes fabricated in the same way as tubes and photo-co-immobilized with rhBDNF or rhNT-3, with or without Schwann cells (SCs), showed an initial burst of neurotrophin release within 24 h, with release diminishing progressively for 21 days thereafter. SCs attained their typical bipolar conformation on membranes without neurotrophins but adhesion, alignment and proliferation were improved with neurotrophins, particularly rhBDNF. When dorsal root ganglion explants were cultured on membranes containing laminin and fibronectin plus both neurotrophins, neurite outgrowth was lengthier compared to combining one neurotrophin with laminin and fibronectin. Thus, these gelatin membranes allow SC survival and effectively release growth factors and harbor extracellular matrix components to improve cell survival and neurite growth. These scaffolds, based on the combination of cross-linked gelatin technology and incorporation of neurotrophins and extracellular matrix components, are promising candidates for spinal cord repair.
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11
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Huang TL, Hung YY, Lee CT, Chen RF. Serum protein levels of brain-derived neurotrophic factor and tropomyosin-related kinase B in bipolar disorder: effects of mood stabilizers. Neuropsychobiology 2012; 65:65-9. [PMID: 22222435 DOI: 10.1159/000328991] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 04/27/2011] [Indexed: 11/19/2022]
Abstract
AIM In this study, we investigated serum protein levels of brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase B (TrkB) in patients with bipolar disorder. METHODS Over a 2-year period, 26 patients with bipolar I disorder (manic episode) and 56 healthy controls were recruited. The Young Mania Rating Scale scores of patients with bipolar mania were >26. Serum BDNF and TrkB protein levels were measured with ELISA kits. RESULTS Using ANCOVA with age adjustment, we found that there were no significant differences in serum BDNF protein levels between patients with bipolar mania and healthy controls (p = 0.582). In contrast, the serum TrkB protein level was significantly higher in bipolar mania patients than in healthy controls (p = 0.001), especially in women (p = 0.001). Of 26 patients with bipolar mania, 21 underwent a second measurement of serum BDNF and TrkB protein levels after a 4-week treatment with mood stabilizers. There were no significant changes in serum BDNF or TrkB protein levels. CONCLUSION These findings suggest that serum TrkB protein levels may play an important role in the psychopathology of bipolar mania. However, a larger sample size is needed to confirm these results.
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Affiliation(s)
- Tiao-Lai Huang
- Department of Psychiatry, Chang Gung Memorial Hospital - Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Taiwan, ROC
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12
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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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Fobian K, Owczarek S, Budtz C, Bock E, Berezin V, Pedersen MV. Peptides derived from the solvent-exposed loops 3 and 4 of BDNF bind TrkB and p75(NTR) receptors and stimulate neurite outgrowth and survival. J Neurosci Res 2010; 88:1170-81. [PMID: 19908279 DOI: 10.1002/jnr.22285] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) is critically involved in modeling the developing nervous system and is an important regulator of a variety of crucial functions in the mature CNS. BDNF exerts its action through interactions with two transmembrane receptors, either separately or in concert. BDNF has been implicated in several neurological disorders, and irregularities in BDNF function may have severe consequences. Administration of BDNF as a drug has thus far yielded few practicable results, and the potential side effects when using a multifunctional protein are substantial. In an effort to produce more specific compounds without side effects, small peptides mimicking protein function have been developed. The present study characterized two mimetic peptides, Betrofin 3 and Betrofin 4, derived from the BDNF sequence. Both Betrofins bound the cognate BDNF receptors, TrkB and p75(NTR), and induced neurite outgrowth and enhanced neuronal survival, probably by inducing signaling through tha Akt and MAPK pathways. Distinct, charged residues within the Betrofin sequences were identified as important for generating the neuritogenic response, which was also inhibited when BDNF was added together with either Betrofin, indicating partial agonistic effects of the peptides. Thus, two peptides derived from BDNF induced neurite outgrowth and enhanced neuronal survival, probably through binding to BDNF receptors.
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Affiliation(s)
- Kristina Fobian
- Protein Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Denmark
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A selective TrkB agonist with potent neurotrophic activities by 7,8-dihydroxyflavone. Proc Natl Acad Sci U S A 2010; 107:2687-92. [PMID: 20133810 DOI: 10.1073/pnas.0913572107] [Citation(s) in RCA: 508] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF), a cognate ligand for the tyrosine kinase receptor B (TrkB) receptor, mediates neuronal survival, differentiation, synaptic plasticity, and neurogenesis. However, BDNF has a poor pharmacokinetic profile that limits its therapeutic potential. Here we report the identification of 7,8-dihydroxyflavone as a bioactive high-affinity TrkB agonist that provokes receptor dimerization and autophosphorylation and activation of downstream signaling. 7,8-Dihydroxyflavone protected wild-type, but not TrkB-deficient, neurons from apoptosis. Administration of 7,8-dihydroxyflavone to mice activated TrkB in the brain, inhibited kainic acid-induced toxicity, decreased infarct volumes in stroke in a TrkB-dependent manner, and was neuroprotective in an animal model of Parkinson disease. Thus, 7,8-dihydroxyflavone imitates BDNF and acts as a robust TrkB agonist, providing a powerful therapeutic tool for the treatment of various neurological diseases.
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15
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Gray J, Yeo G, Hung C, Keogh J, Clayton P, Banerjee K, McAulay A, O'Rahilly S, Farooqi IS. Functional characterization of human NTRK2 mutations identified in patients with severe early-onset obesity. Int J Obes (Lond) 2006; 31:359-64. [PMID: 16702999 DOI: 10.1038/sj.ijo.0803390] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE The neurotrophin receptor TrkB has been implicated in the regulation of energy homeostasis in rodents. We have previously identified four rare missense mutations in the gene encoding TrkB, NTRK2, in 198 severely obese children with developmental delay. We have now undertaken a more detailed analysis of the in vitro functional consequences of the mutations identified: I98V, P660L, T821A and Y722C. DESIGN Wild-type and mutant TrkB receptor constructs were stably transfected into PC12 cells and the signaling responses to the endogenous ligand, brain-derived neurotrophic factor (BDNF), were examined by Western blotting of cell lysates. In the case of Y722C, PC12 cells stably expressing this mutant were studied for their ability to respond to BDNF by promoting neurite outgrowth and cell survival. RESULTS Further functional characterization of the previously reported Y722C TrkB mutation reveals impaired activation of mitogen-activated protein kinase, phospholipase C-gamma and Akt, as well as reduced BDNF-induced neurite outgrowth and cell survival in stably transfected PC12 cell lines. However, the signaling properties of I98V, P660L and T821A were all indistinguishable from wild type. CONCLUSION We provide further evidence for the impairment in signaling by Y722C and show that as well as a loss of signaling, this mutation affects the ability of TrkB to promote neurite outgrowth in response to BDNF. Thus, impaired hypothalamic neurogenesis may contribute to the severe hyperphagia and obesity seen in the individual harboring the Y722C variant. The other three rare TrkB variants do not show reduced autophosphorylation or impaired downstream signaling in vitro and, as yet, it is unclear whether these variants contribute to obesity in these patients.
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Affiliation(s)
- J Gray
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
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16
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Miller R, King MA, Heaton MB, Walker DW. The effects of chronic ethanol consumption on neurotrophins and their receptors in the rat hippocampus and basal forebrain. Brain Res 2002; 950:137-47. [PMID: 12231238 DOI: 10.1016/s0006-8993(02)03014-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Damage to the basal forebrain frequently results in deficits in learning and memory. Mnenonic dysfunction also occurs following prolonged ethanol consumption in humans and in animal models of chronic ethanol intake, accompanied by specific abnormalities in synaptic transmission between the basal forebrain and hippocampus. The integrity of at least some of the reciprocal neuronal connections between these brain regions is influenced by target-derived neurotrophic factors. We used a semiquantitative reverse transcription polymerase chain reaction technique to measure the messenger RNA for neurotrophins BDNF and NGF, and for their receptors trkB, trkA, and the low affinity receptor, p75(NTR) in the hippocampus and basal forebrain of rats after 28 weeks of alcohol consumption without malnutrition. This chronic ethanol treatment (CET) resulted in a marked and selective reduction in basal forebrain trkA mRNA. Western blotting revealed a similar reduction of basal forebrain trkA protein. CET effects on basal forebrain trkA may reflect impaired NGF signaling that could compromise septohippocampal synaptic connections, cholinergic differentiation, and emergent functional abilities dependent on these properties.
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MESH Headings
- Alcohol Drinking/metabolism
- Animals
- Brain-Derived Neurotrophic Factor/biosynthesis
- Brain-Derived Neurotrophic Factor/genetics
- Brain-Derived Neurotrophic Factor/metabolism
- Ethanol/administration & dosage
- Hippocampus/drug effects
- Hippocampus/metabolism
- Male
- Prosencephalon/drug effects
- Prosencephalon/metabolism
- RNA, Messenger/biosynthesis
- Rats
- Rats, Long-Evans
- Receptor, Nerve Growth Factor
- Receptor, trkA/biosynthesis
- Receptor, trkA/genetics
- Receptor, trkA/metabolism
- Receptor, trkB/biosynthesis
- Receptor, trkB/genetics
- Receptor, trkB/metabolism
- Receptors, Nerve Growth Factor/biosynthesis
- Receptors, Nerve Growth Factor/genetics
- Receptors, Nerve Growth Factor/metabolism
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Affiliation(s)
- R Miller
- Department of Neuroscience and McKnight Brain Institute, Box 100244 JHMHC, University of Florida College of Medicine, Gainesville, FL 32610-0244, USA.
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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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Murer MG, Yan Q, Raisman-Vozari R. Brain-derived neurotrophic factor in the control human brain, and in Alzheimer's disease and Parkinson's disease. Prog Neurobiol 2001; 63:71-124. [PMID: 11040419 DOI: 10.1016/s0301-0082(00)00014-9] [Citation(s) in RCA: 624] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is a small dimeric protein, structurally related to nerve growth factor, which is abundantly and widely expressed in the adult mammalian brain. BDNF has been found to promote survival of all major neuronal types affected in Alzheimer's disease and Parkinson's disease, like hippocampal and neocortical neurons, cholinergic septal and basal forebrain neurons, and nigral dopaminergic neurons. In this article, we summarize recent work on the molecular and cellular biology of BDNF, including current ideas about its intracellular trafficking, regulated synthesis and release, and actions at the synaptic level, which have considerably expanded our conception of BDNF actions in the central nervous system. But our primary aim is to review the literature regarding BDNF distribution in the human brain, and the modifications of BDNF expression which occur in the brain of individuals with Alzheimer's disease and Parkinson's disease. Our knowledge concerning BDNF actions on the neuronal populations affected in these pathological states is also reviewed, with an aim at understanding its pathogenic and pathophysiological relevance.
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Affiliation(s)
- M G Murer
- Departamento de Fisiologia, Facultad de Medicina, Universidad de Buenos Aires, Paraguay.
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Maliartchouk S, Debeir T, Beglova N, Cuello AC, Gehring K, Saragovi HU. Genuine monovalent ligands of TrkA nerve growth factor receptors reveal a novel pharmacological mechanism of action. J Biol Chem 2000; 275:9946-56. [PMID: 10744669 DOI: 10.1074/jbc.275.14.9946] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Developing small molecule agonistic ligands for tyrosine kinase receptors has been difficult, and it is generally thought that such ligands require bivalency. Moreover, multisubunit receptors are difficult to target, because each subunit contributes to ligand affinity, and each subunit may have distinct and sometimes opposing functions. Here, the nerve growth factor receptor subunits p75 and the tyrosine kinase TrkA were studied using artificial ligands that bind specifically to their extracellular domain. Bivalent TrkA ligands afford robust signals. However, genuine monomeric and monovalent TrkA ligands afford partial agonism, activate the tyrosine kinase activity, cause receptor internalization, and induce survival and differentiation in cell lines and primary neurons. Monomeric and monovalent TrkA ligands can synergize with ligands that bind the p75 subunit. However, the p75 ligands used in this study must be bivalent, and monovalent p75 ligands have no effect. These findings will be useful in designing and developing screens of small molecules selective for tyrosine kinase receptors and indicate that strategies for designing agonists of multisubunit receptors require consideration of the role of each subunit. Last, the strategy of using anti-receptor mAbs and small molecule hormone mimics as receptor ligands could be applied to the study of many other heteromeric cell surface receptors.
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Affiliation(s)
- S Maliartchouk
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
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O'Connell L, Hongo JA, Presta LG, Tsoulfas P. TrkA amino acids controlling specificity for nerve growth factor. J Biol Chem 2000; 275:7870-7. [PMID: 10713102 DOI: 10.1074/jbc.275.11.7870] [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: 11/06/2022] Open
Abstract
Neurotrophins are important for the development and maintenance of the vertebrate nervous system, mediating their signal into the cell by specific interaction with tyrosine kinase receptors of the Trk family. The extracellular portion of the Trk receptors has been previously proposed to consist of a cysteine-rich motif, a leucine-rich motif, a second cysteine-rich motif followed by two immunoglobulin-like domains. Earlier studies have shown that a major neurotrophin-binding site in the Trk receptors resides in the second immunoglobulin-like domain. Although the individual amino acids in TrkA involved in binding to nerve growth factor (NGF) and those in TrkC involved in binding to neurotrophin-3 have been mapped in this domain, the Trk amino acids that provide specificity remained unclear. In this study, a minimum set of residues in the human TrkC second immunoglobulin-like domain, which does not bind nerve growth factor (NGF), were substituted with those from human TrkA. The resulting Trk variant recruited binding of NGF equivalent to TrkA, maintained neurotrophin-3 binding equivalent to TrkC, and also bound brain-derived neurotrophin, although with lower affinity compared with TrkB. This implies that the amino acids in the second immunoglobulin-like domain that determine Trk specificity are distinct for each Trk.
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Affiliation(s)
- L O'Connell
- Departments of Immunology, Genentech Inc., South San Francisco, California 94080, USA
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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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Barth HG, Boyes BE, Jackson C. Size Exclusion Chromatography and Related Separation Techniques. Anal Chem 1998. [DOI: 10.1021/a1980015t] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Howard G. Barth
- Central Research and Development, DuPont Company, Experimental Station, P.O. Box 80228, Wilmington, Delaware 19880-0228, Little Falls Analytical DivisionNewport, Hewlett-Packard Company, 538 First State Boulevard, Newport, Delaware 19804, and Marshall Laboratory, DuPont Automative Products, 3401 Grays Ferry Avenue, Philadelphia, Pennsylvania 19146
| | - Barry E. Boyes
- Central Research and Development, DuPont Company, Experimental Station, P.O. Box 80228, Wilmington, Delaware 19880-0228, Little Falls Analytical DivisionNewport, Hewlett-Packard Company, 538 First State Boulevard, Newport, Delaware 19804, and Marshall Laboratory, DuPont Automative Products, 3401 Grays Ferry Avenue, Philadelphia, Pennsylvania 19146
| | - Christian Jackson
- Central Research and Development, DuPont Company, Experimental Station, P.O. Box 80228, Wilmington, Delaware 19880-0228, Little Falls Analytical DivisionNewport, Hewlett-Packard Company, 538 First State Boulevard, Newport, Delaware 19804, and Marshall Laboratory, DuPont Automative Products, 3401 Grays Ferry Avenue, Philadelphia, Pennsylvania 19146
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