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Zoltowska KM, Das U, Lismont S, Enzlein T, Maesako M, Houser MCQ, Franco ML, Özcan B, Gomes Moreira D, Karachentsev D, Becker A, Hopf C, Vilar M, Berezovska O, Mobley W, Chávez-Gutiérrez L. Alzheimer's disease linked Aβ42 exerts product feedback inhibition on γ-secretase impairing downstream cell signaling. eLife 2024; 12:RP90690. [PMID: 39027984 PMCID: PMC11259434 DOI: 10.7554/elife.90690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024] Open
Abstract
Amyloid β (Aβ) peptides accumulating in the brain are proposed to trigger Alzheimer's disease (AD). However, molecular cascades underlying their toxicity are poorly defined. Here, we explored a novel hypothesis for Aβ42 toxicity that arises from its proven affinity for γ-secretases. We hypothesized that the reported increases in Aβ42, particularly in the endolysosomal compartment, promote the establishment of a product feedback inhibitory mechanism on γ-secretases, and thereby impair downstream signaling events. We conducted kinetic analyses of γ-secretase activity in cell-free systems in the presence of Aβ, as well as cell-based and ex vivo assays in neuronal cell lines, neurons, and brain synaptosomes to assess the impact of Aβ on γ-secretases. We show that human Aβ42 peptides, but neither murine Aβ42 nor human Aβ17-42 (p3), inhibit γ-secretases and trigger accumulation of unprocessed substrates in neurons, including C-terminal fragments (CTFs) of APP, p75, and pan-cadherin. Moreover, Aβ42 treatment dysregulated cellular homeostasis, as shown by the induction of p75-dependent neuronal death in two distinct cellular systems. Our findings raise the possibility that pathological elevations in Aβ42 contribute to cellular toxicity via the γ-secretase inhibition, and provide a novel conceptual framework to address Aβ toxicity in the context of γ-secretase-dependent homeostatic signaling.
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Affiliation(s)
| | - Utpal Das
- Department of Neurosciences, University of California San DiegoLa JollaUnited States
| | - Sam Lismont
- VIB-KU Leuven Center for Brain & Disease ResearchLeuvenBelgium
| | - Thomas Enzlein
- VIB-KU Leuven Center for Brain & Disease ResearchLeuvenBelgium
- Center for Mass Spectrometry and Optical Spectroscopy (CeMOS), Mannheim University of Applied SciencesMannheimGermany
| | - Masato Maesako
- Department of Neurology, Massachusetts General Hospital/Harvard Medical SchoolCharlestownUnited States
| | - Mei CQ Houser
- Department of Neurology, Massachusetts General Hospital/Harvard Medical SchoolCharlestownUnited States
| | - Maria Luisa Franco
- Molecular Basis of Neurodegeneration Unit, Instituto de Biomedicina de ValenciaValenciaSpain
| | - Burcu Özcan
- VIB-KU Leuven Center for Brain & Disease ResearchLeuvenBelgium
| | | | - Dmitry Karachentsev
- Department of Neurosciences, University of California San DiegoLa JollaUnited States
| | - Ann Becker
- Department of Neurosciences, University of California San DiegoLa JollaUnited States
| | - Carsten Hopf
- Center for Mass Spectrometry and Optical Spectroscopy (CeMOS), Mannheim University of Applied SciencesMannheimGermany
- Medical Faculty, Heidelberg UniversityHeidelbergGermany
- Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg UniversityHeidelbergGermany
| | - Marçal Vilar
- Molecular Basis of Neurodegeneration Unit, Instituto de Biomedicina de ValenciaValenciaSpain
| | - Oksana Berezovska
- Department of Neurology, Massachusetts General Hospital/Harvard Medical SchoolCharlestownUnited States
| | - William Mobley
- Department of Neurosciences, University of California San DiegoLa JollaUnited States
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2
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Nguyen H, Glaaser IW, Slesinger PA. Direct modulation of G protein-gated inwardly rectifying potassium (GIRK) channels. Front Physiol 2024; 15:1386645. [PMID: 38903913 PMCID: PMC11187414 DOI: 10.3389/fphys.2024.1386645] [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: 02/15/2024] [Accepted: 04/08/2024] [Indexed: 06/22/2024] Open
Abstract
Ion channels play a pivotal role in regulating cellular excitability and signal transduction processes. Among the various ion channels, G-protein-coupled inwardly rectifying potassium (GIRK) channels serve as key mediators of neurotransmission and cellular responses to extracellular signals. GIRK channels are members of the larger family of inwardly-rectifying potassium (Kir) channels. Typically, GIRK channels are activated via the direct binding of G-protein βγ subunits upon the activation of G-protein-coupled receptors (GPCRs). GIRK channel activation requires the presence of the lipid signaling molecule, phosphatidylinositol 4,5-bisphosphate (PIP2). GIRK channels are also modulated by endogenous proteins and other molecules, including RGS proteins, cholesterol, and SNX27 as well as exogenous compounds, such as alcohol. In the last decade or so, several groups have developed novel drugs and small molecules, such as ML297, GAT1508 and GiGA1, that activate GIRK channels in a G-protein independent manner. Here, we aim to provide a comprehensive overview focusing on the direct modulation of GIRK channels by G-proteins, PIP2, cholesterol, and novel modulatory compounds. These studies offer valuable insights into the underlying molecular mechanisms of channel function, and have potential implications for both basic research and therapeutic development.
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Affiliation(s)
| | | | - Paul A. Slesinger
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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3
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Zoltowska KM, Das U, Lismont S, Enzlein T, Maesako M, Houser MCQ, Franco ML, Özcan B, Moreira DG, Karachentsev D, Becker A, Hopf C, Vilar M, Berezovska O, Mobley W, Chávez-Gutiérrez L. Alzheimer's disease linked Aβ42 exerts product feedback inhibition on γ-secretase impairing downstream cell signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.02.551596. [PMID: 37577527 PMCID: PMC10418207 DOI: 10.1101/2023.08.02.551596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Amyloid β (Aβ) peptides accumulating in the brain are proposed to trigger Alzheimer's disease (AD). However, molecular cascades underlying their toxicity are poorly defined. Here, we explored a novel hypothesis for Aβ42 toxicity that arises from its proven affinity for γ-secretases. We hypothesized that the reported increases in Aβ42, particularly in the endolysosomal compartment, promote the establishment of a product feedback inhibitory mechanism on γ-secretases, and thereby impair downstream signaling events. We show that human Aβ42 peptides, but neither murine Aβ42 nor human Aβ17-42 (p3), inhibit γ-secretases and trigger accumulation of unprocessed substrates in neurons, including C-terminal fragments (CTFs) of APP, p75 and pan-cadherin. Moreover, Aβ42 treatment dysregulated cellular -homeostasis, as shown by the induction of p75-dependent neuronal death in two distinct cellular systems. Our findings raise the possibility that pathological elevations in Aβ42 contribute to cellular toxicity via the γ-secretase inhibition, and provide a novel conceptual framework to address Aβ toxicity in the context of γ-secretase-dependent homeostatic signaling.
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Affiliation(s)
| | - Utpal Das
- Department of Neurosciences, University of California San Diego, La Jolla, CA, United States of America
| | - Sam Lismont
- VIB-KU Leuven Center for Brain & Disease Research, VIB, Leuven, Belgium
| | - Thomas Enzlein
- VIB-KU Leuven Center for Brain & Disease Research, VIB, Leuven, Belgium
- Center for Mass Spectrometry and Optical Spectroscopy (CeMOS), Mannheim University of Applied Sciences, Mannheim, Germany
| | - Masato Maesako
- Department of Neurology, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA, United States of America
| | - Mei CQ Houser
- Department of Neurology, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA, United States of America
| | - María Luisa Franco
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València (IBV-CSIC), València, Spain
| | - Burcu Özcan
- VIB-KU Leuven Center for Brain & Disease Research, VIB, Leuven, Belgium
| | | | - Dmitry Karachentsev
- Department of Neurosciences, University of California San Diego, La Jolla, CA, United States of America
| | - Ann Becker
- Department of Neurosciences, University of California San Diego, La Jolla, CA, United States of America
| | - Carsten Hopf
- Center for Mass Spectrometry and Optical Spectroscopy (CeMOS), Mannheim University of Applied Sciences, Mannheim, Germany
- Medical Faculty, Heidelberg University, Heidelberg, Germany
- Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Marçal Vilar
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València (IBV-CSIC), València, Spain
| | - Oksana Berezovska
- Department of Neurology, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA, United States of America
| | - William Mobley
- Department of Neurosciences, University of California San Diego, La Jolla, CA, United States of America
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4
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Ramanujan A, Li Z, Ma Y, Lin Z, Ibáñez CF. RhoGDI phosphorylation by PKC promotes its interaction with death receptor p75 NTR to gate axon growth and neuron survival. EMBO Rep 2024; 25:1490-1512. [PMID: 38253689 PMCID: PMC10933337 DOI: 10.1038/s44319-024-00064-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 12/21/2023] [Accepted: 01/05/2024] [Indexed: 01/24/2024] Open
Abstract
How receptors juggle their interactions with multiple downstream effectors remains poorly understood. Here we show that the outcome of death receptor p75NTR signaling is determined through competition of effectors for interaction with its intracellular domain, in turn dictated by the nature of the ligand. While NGF induces release of RhoGDI through recruitment of RIP2, thus decreasing RhoA activity in favor of NFkB signaling, MAG induces PKC-mediated phosphorylation of the RhoGDI N-terminus, promoting its interaction with the juxtamembrane domain of p75NTR, disengaging RIP2, and enhancing RhoA activity in detriment of NF-kB. This results in stunted neurite outgrowth and apoptosis in cerebellar granule neurons. If presented simultaneously, MAG prevails over NGF. The NMR solution structure of the complex between the RhoGDI N-terminus and p75NTR juxtamembrane domain reveals previously unknown structures of these proteins and clarifies the mechanism of p75NTR activation. These results show how ligand-directed competition between RIP2 and RhoGDI for p75NTR engagement determine axon growth and neuron survival. Similar principles are likely at work in other receptors engaging multiple effectors and signaling pathways.
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Affiliation(s)
- Ajeena Ramanujan
- Department of Physiology and Life Sciences Institute, National University of Singapore, 117456, Singapore, Singapore
| | - Zhen Li
- Tianjin Key Laboratory of Function and Application of Biological Macromolecular Structures, School of Life Sciences, Tianjin University, Tianjin, 300072, China
| | - Yanchen Ma
- Peking University School of Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, 100871, Beijing, China
- Chinese Institute for Brain Research, Life Science Park, 102206, Beijing, China
| | - Zhi Lin
- Tianjin Key Laboratory of Function and Application of Biological Macromolecular Structures, School of Life Sciences, Tianjin University, Tianjin, 300072, China
| | - Carlos F Ibáñez
- Department of Physiology and Life Sciences Institute, National University of Singapore, 117456, Singapore, Singapore.
- Peking University School of Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, 100871, Beijing, China.
- Chinese Institute for Brain Research, Life Science Park, 102206, Beijing, China.
- Department of Neuroscience, Karolinska Institute, Stockholm, 17177, Sweden.
- Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch, 7600, South Africa.
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5
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Bogacheva PO, Molchanova AI, Pravdivceva ES, Miteva AS, Balezina OP, Gaydukov AE. ProBDNF and Brain-Derived Neurotrophic Factor Prodomain Differently Modulate Acetylcholine Release in Regenerating and Mature Mouse Motor Synapses. Front Cell Neurosci 2022; 16:866802. [PMID: 35591942 PMCID: PMC9110780 DOI: 10.3389/fncel.2022.866802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/18/2022] [Indexed: 11/30/2022] Open
Abstract
The effects of brain-derived neurotrophic factor (BDNF) processing by-products (proBDNF and BDNF prodomain) on the activity of mouse neuromuscular junctions (NMJs) were studied in synapses formed during the reinnervation of extensor digitorum longus muscle (m. EDL) and mature synapses of the diaphragm. The parameters of spontaneous miniature endplate potentials (MEPPs) and evoked endplate potentials (EPPs) were analyzed in presence of each of the BDNF maturation products (both – 1 nM). In newly formed NMJs, proBDNF caused an increase in the resting membrane potential of muscle fibers and a decrease in the frequency of MEPPs, which was prevented by tertiapin-Q, a G-protein-coupled inwardly rectifying potassium channels (GIRK) blocker but not by p75 receptor signaling inhibitor TAT-Pep5. proBDNF had no effect on the parameters of EPPs. BDNF prodomain in newly formed synapses had effects different from those of proBDNF: it increased the amplitude of MEPPs, which was prevented by vesamicol, an inhibitor of vesicular acetylcholine (ACh) transporter; and reduced the quantal content of EPPs. In mature NMJs, proBDNF did not influence MEPPs parameters, but BDNF prodomain suppressed both spontaneous and evoked ACh release: decreased the frequency and amplitude of MEPPs, and the amplitude and quantal content of EPPs. This effect of the BDNF prodomain was prevented by blocking GIRK channels, by TAT-Pep5 or by Rho-associated protein kinase (ROCK) inhibitor Y-27632. At the same time, the BDNF prodomain did not show any inhibitory effects in diaphragm motor synapses of pannexin 1 knockout mice, which have impaired purinergic regulation of neuromuscular transmission. The data obtained suggest that there is a previously unknown mechanism for the acute suppression of spontaneous and evoked ACh release in mature motor synapses, which involves the activation of p75 receptors, ROCK and GIRK channels by BDNF prodomain and requires interaction with metabotropic purinoreceptors. In general, our results show that both the precursor of BDNF and the product of its maturation have predominantly inhibitory effects on spontaneous and evoked ACh release in newly formed or functionally mature neuromuscular junctions, which are mainly opposite to the effects of BDNF. The inhibitory influences of both proteins related to brain neurotrophin are mediated via GIRK channels of mouse NMJs.
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Jeremic D, Jiménez-Díaz L, Navarro-López JD. Past, present and future of therapeutic strategies against amyloid-β peptides in Alzheimer's disease: a systematic review. Ageing Res Rev 2021; 72:101496. [PMID: 34687956 DOI: 10.1016/j.arr.2021.101496] [Citation(s) in RCA: 120] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 09/30/2021] [Accepted: 10/18/2021] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in ageing, affecting around 46 million people worldwide but few treatments are currently available. The etiology of AD is still puzzling, and new drugs development and clinical trials have high failure rates. Urgent outline of an integral (multi-target) and effective treatment of AD is needed. Accumulation of amyloid-β (Aβ) peptides is considered one of the fundamental neuropathological pillars of the disease, and its dyshomeostasis has shown a crucial role in AD onset. Therefore, many amyloid-targeted therapies have been investigated. Here, we will systematically review recent (from 2014) investigational, follow-up and review studies focused on anti-amyloid strategies to summarize and analyze their current clinical potential. Combination of anti-Aβ therapies with new developing early detection biomarkers and other therapeutic agents acting on early functional AD changes will be highlighted in this review. Near-term approval seems likely for several drugs acting against Aβ, with recent FDA approval of a monoclonal anti-Aβ oligomers antibody -aducanumab- raising hopes and controversies. We conclude that, development of oligomer-epitope specific Aβ treatment and implementation of multiple improved biomarkers and risk prediction methods allowing early detection, together with therapies acting on other factors such as hyperexcitability in early AD, could be the key to slowing this global pandemic.
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Bony AR, McArthur JR, Finol-Urdaneta RK, Adams DJ. Analgesic α-conotoxins modulate native and recombinant GIRK1/2 channels via activation of GABA B receptors and reduce neuroexcitability. Br J Pharmacol 2021; 179:179-198. [PMID: 34599513 DOI: 10.1111/bph.15690] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 08/25/2021] [Accepted: 08/30/2021] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND AND PURPOSE Activation of GIRK channels via G protein-coupled GABAB receptors has been shown to attenuate nociceptive transmission. The analgesic α-conotoxin Vc1.1 activates GABAB receptors resulting in inhibition of Cav 2.2 and Cav 2.3 channels in mammalian primary afferent neurons. Here, we investigated the effects of analgesic α-conotoxins on recombinant and native GIRK-mediated K+ currents and on neuronal excitability. EXPERIMENTAL APPROACH The effects of analgesic α-conotoxins, Vc1.1, RgIA, and PeIA, were investigated on inwardly-rectifying K+ currents in HEK293T cells recombinantly co-expressing either heteromeric human GIRK1/2 or homomeric GIRK2 subunits, with GABAB receptors. The effects of α-conotoxin Vc1.1 and baclofen were studied on GIRK-mediated K+ currents and the passive and active electrical properties of adult mouse dorsal root ganglion neurons. KEY RESULTS Analgesic α-conotoxins Vc1.1, RgIA, and PeIA potentiate inwardly-rectifying K+ currents in HEK293T cells recombinantly expressing human GIRK1/2 channels and GABAB receptors. GABAB receptor-dependent GIRK channel potentiation by Vc1.1 and baclofen occurs via a pertussis toxin-sensitive G protein and is inhibited by the selective GABAB receptor antagonist CGP 55845. In adult mouse dorsal root ganglion neurons, GABAB receptor-dependent GIRK channel potentiation by Vc1.1 and baclofen hyperpolarizes the cell membrane potential and reduces excitability. CONCLUSIONS AND IMPLICATIONS This is the first report of GIRK channel potentiation via allosteric α-conotoxin Vc1.1-GABAB receptor agonism, leading to decreased neuronal excitability. Such action potentially contributes to the analgesic effects of Vc1.1 and baclofen observed in vivo.
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Affiliation(s)
- Anuja R Bony
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
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8
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Sankorrakul K, Qian L, Thangnipon W, Coulson EJ. Is there a role for the p75 neurotrophin receptor in mediating degeneration during oxidative stress and after hypoxia? J Neurochem 2021; 158:1292-1306. [PMID: 34109634 DOI: 10.1111/jnc.15451] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 06/01/2021] [Accepted: 06/04/2021] [Indexed: 12/21/2022]
Abstract
Cholinergic basal forebrain (cBF) neurons are particularly vulnerable to degeneration following trauma and in neurodegenerative conditions. One reason for this is their characteristic expression of the p75 neurotrophin receptor (p75NTR ), which is up-regulated and mediates neuronal death in a range of neurological and neurodegenerative conditions, including dementia, stroke and ischaemia. The signalling pathway by which p75NTR signals cell death is incompletely characterised, but typically involves activation by neurotrophic ligands and signalling through c-Jun kinase, resulting in caspase activation via mitochondrial apoptotic signalling pathways. Less well appreciated is the link between conditions of oxidative stress and p75NTR death signalling. Here, we review the literature describing what is currently known regarding p75NTR death signalling in environments of oxidative stress and hypoxia to highlight the overlap in signalling pathways and the implications for p75NTR signalling in cBF neurons. We propose that there is a causal relationship and define key questions to test this assertion.
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Affiliation(s)
- Kornraviya Sankorrakul
- School of Biomedical Sciences, Faculty of Medicine and Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Qld., Australia.,Research Center for Neuroscience, Institute of Molecular Biosciences, Mahidol University, Salaya, Thailand
| | - Lei Qian
- School of Biomedical Sciences, Faculty of Medicine and Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Qld., Australia
| | - Wipawan Thangnipon
- Research Center for Neuroscience, Institute of Molecular Biosciences, Mahidol University, Salaya, Thailand
| | - Elizabeth J Coulson
- School of Biomedical Sciences, Faculty of Medicine and Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Qld., Australia
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9
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Luo M, Shi X, Guo Q, Li S, Zhang Q, Sun X, Piao F. 2,5-Hexanedione induced apoptosis in rat spinal cord neurons and VSC4.1 cells via the proNGF/p75NTR and JNK pathways. Biosci Rep 2021; 41:BSR20204264. [PMID: 33792642 PMCID: PMC8035625 DOI: 10.1042/bsr20204264] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/04/2021] [Accepted: 03/31/2021] [Indexed: 01/10/2023] Open
Abstract
Increasing evidence suggests that n-hexane induces nerve injury via neuronal apoptosis induced by its active metabolite 2,5-hexanedione (HD). However, the underlying mechanism remains unknown. Studies have confirmed that pro-nerve growth factor (proNGF), a precursor of mature nerve growth factor (mNGF), might activate apoptotic signaling by binding to p75 neurotrophin receptor (p75NTR) in neurons. Therefore, we studied the mechanism of the proNGF/p75NTR pathway in HD-induced neuronal apoptosis. Sprague-Dawley (SD) rats were injected with 400 mg/kg HD once a day for 5 weeks, and VSC4.1 cells were treated with 10, 20, and 40 mM HD in vitro. Results showed that HD effectively induced neuronal apoptosis. Moreover, it up-regulated proNGF and p75NTR levels, activated c-Jun N-terminal kinase (JNK) and c-Jun, and disrupted the balance between B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax). Our findings revealed that the proNGF/p75NTR signaling pathway was involved in HD-induced neuronal apoptosis; it can serve as a theoretical basis for further exploration of the neurotoxic mechanisms of HD.
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Affiliation(s)
- Mengxin Luo
- Department of Occupational and Environmental Health, school of public health, Dalian Medical University, Dalian 116044, China
| | - Xiaoxia Shi
- Department of Occupational and Environmental Health, school of public health, Dalian Medical University, Dalian 116044, China
| | - Qi Guo
- Department of Environment Hygiene Division, Dalian Center for Disease Control and Prevention, Dalian 116021, China
| | - Shuangyue Li
- Department of Occupational and Environmental Health, school of public health, Dalian Medical University, Dalian 116044, China
| | - Qing Zhang
- Department of Integrative Laboratory, Affiliated Zhongshan Hospital of Dalian University, Dalian 116001, China
| | - Xiuyan Sun
- Department of Integrative Laboratory, Affiliated Zhongshan Hospital of Dalian University, Dalian 116001, China
| | - Fengyuan Piao
- Department of Integrative Laboratory, Affiliated Zhongshan Hospital of Dalian University, Dalian 116001, China
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10
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Franco ML, García-Carpio I, Comaposada-Baró R, Escribano-Saiz JJ, Chávez-Gutiérrez L, Vilar M. TrkA-mediated endocytosis of p75-CTF prevents cholinergic neuron death upon γ-secretase inhibition. Life Sci Alliance 2021; 4:4/4/e202000844. [PMID: 33536237 PMCID: PMC7898468 DOI: 10.26508/lsa.202000844] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 01/11/2021] [Accepted: 01/11/2021] [Indexed: 12/13/2022] Open
Abstract
The findings shed light into the adverse effects of GSIs observed in the Alzheimer’s field and explain, at least in part, the unexpected worsening in cognition observed in the semagacestat Phase 3 trial. γ-secretase inhibitors (GSI) were developed to reduce the generation of Aβ peptide to find new Alzheimer’s disease treatments. Clinical trials on Alzheimer’s disease patients, however, showed several side effects that worsened the cognitive symptoms of the treated patients. The observed side effects were partially attributed to Notch signaling. However, the effect on other γ-secretase substrates, such as the p75 neurotrophin receptor (p75NTR) has not been studied in detail. p75NTR is highly expressed in the basal forebrain cholinergic neurons (BFCNs) during all life. Here, we show that GSI treatment induces the oligomerization of p75CTF leading to the cell death of BFCNs, and that this event is dependent on TrkA activity. The oligomerization of p75CTF requires an intact cholesterol recognition sequence (CRAC) and the constitutive binding of TRAF6, which activates the JNK and p38 pathways. Remarkably, TrkA rescues from cell death by a mechanism involving the endocytosis of p75CTF. These results suggest that the inhibition of γ-secretase activity in aged patients, where the expression of TrkA in the BFCNs is already reduced, could accelerate cholinergic dysfunction and promote neurodegeneration.
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Affiliation(s)
- María Luisa Franco
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València (IBV-CSIC), València, Spain
| | - Irmina García-Carpio
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València (IBV-CSIC), València, Spain
| | - Raquel Comaposada-Baró
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València (IBV-CSIC), València, Spain
| | - Juan J Escribano-Saiz
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València (IBV-CSIC), València, Spain
| | - Lucía Chávez-Gutiérrez
- Vlaams Instituut voor Biotechnologie Katholieke Universiteit (VIB-KU) Leuven Center for Brain and Disease, Leuven, Belgium
| | - Marçal Vilar
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València (IBV-CSIC), València, Spain
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11
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Therapeutic potential of targeting G protein-gated inwardly rectifying potassium (GIRK) channels in the central nervous system. Pharmacol Ther 2021; 223:107808. [PMID: 33476640 DOI: 10.1016/j.pharmthera.2021.107808] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 01/05/2021] [Indexed: 12/15/2022]
Abstract
G protein-gated inwardly rectifying potassium channels (Kir3/GirK) are important for maintaining resting membrane potential, cell excitability and inhibitory neurotransmission. Coupled to numerous G protein-coupled receptors (GPCRs), they mediate the effects of many neurotransmitters, neuromodulators and hormones contributing to the general homeostasis and particular synaptic plasticity processes, learning, memory and pain signaling. A growing number of behavioral and genetic studies suggest a critical role for the appropriate functioning of the central nervous system, as well as their involvement in many neurologic and psychiatric conditions, such as neurodegenerative diseases, mood disorders, attention deficit hyperactivity disorder, schizophrenia, epilepsy, alcoholism and drug addiction. Hence, GirK channels emerge as a very promising tool to be targeted in the current scenario where these conditions already are or will become a global public health problem. This review examines recent findings on the physiology, function, dysfunction, and pharmacology of GirK channels in the central nervous system and highlights the relevance of GirK channels as a worthful potential target to improve therapies for related diseases.
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12
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Boskovic Z, Meier S, Wang Y, Milne M, Onraet T, Tedoldi A, Coulson E. Regulation of cholinergic basal forebrain development, connectivity, and function by neurotrophin receptors. Neuronal Signal 2019; 3:NS20180066. [PMID: 32269831 PMCID: PMC7104233 DOI: 10.1042/ns20180066] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/15/2019] [Accepted: 01/15/2019] [Indexed: 12/11/2022] Open
Abstract
Cholinergic basal forebrain (cBF) neurons are defined by their expression of the p75 neurotrophin receptor (p75NTR) and tropomyosin-related kinase (Trk) neurotrophin receptors in addition to cholinergic markers. It is known that the neurotrophins, particularly nerve growth factor (NGF), mediate cholinergic neuronal development and maintenance. However, the role of neurotrophin signalling in regulating adult cBF function is less clear, although in dementia, trophic signalling is reduced and p75NTR mediates neurodegeneration of cBF neurons. Here we review the current understanding of how cBF neurons are regulated by neurotrophins which activate p75NTR and TrkA, B or C to influence the critical role that these neurons play in normal cortical function, particularly higher order cognition. Specifically, we describe the current evidence that neurotrophins regulate the development of basal forebrain neurons and their role in maintaining and modifying mature basal forebrain synaptic and cortical microcircuit connectivity. Understanding the role neurotrophin signalling plays in regulating the precision of cholinergic connectivity will contribute to the understanding of normal cognitive processes and will likely provide additional ideas for designing improved therapies for the treatment of neurological disease in which cholinergic dysfunction has been demonstrated.
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Affiliation(s)
- Zoran Boskovic
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Sonja Meier
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Yunpeng Wang
- Faculty of Medicine, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
- College of Forensic Science, Xi’an Jiaotong University, Shaanxi, China
| | - Michael R. Milne
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia
- Faculty of Medicine, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Tessa Onraet
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Angelo Tedoldi
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Elizabeth J. Coulson
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia
- Faculty of Medicine, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
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13
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Puigdellívol M, Saavedra A, Pérez-Navarro E. Cognitive dysfunction in Huntington's disease: mechanisms and therapeutic strategies beyond BDNF. Brain Pathol 2018; 26:752-771. [PMID: 27529673 DOI: 10.1111/bpa.12432] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 07/08/2016] [Indexed: 12/15/2022] Open
Abstract
One of the main focuses in Huntington's disease (HD) research, as well as in most neurodegenerative diseases, is the development of new therapeutic strategies, as currently there is no treatment to delay or prevent the progression of the disease. Neuronal dysfunction and neuronal death in HD are caused by a combination of interrelated pathogenic processes that lead to motor, cognitive and psychiatric symptoms. Understanding how mutant huntingtin impacts on a plethora of cellular functions could help to identify new molecular targets. Although HD has been classically classified as a neurodegenerative disease affecting voluntary movement, lately cognitive dysfunction is receiving increased attention as it is very invalidating for patients. Thus, an ambitious goal in HD research is to find altered molecular mechanisms that contribute to cognitive decline. In this review, we have focused on those findings related to corticostriatal and hippocampal cognitive dysfunction in HD, as well as on the underlying molecular mechanisms, which constitute potential therapeutic targets. These include alterations in synaptic plasticity, transcriptional machinery and neurotrophic and neurotransmitter signaling.
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Affiliation(s)
- Mar Puigdellívol
- Departament de Biomedicina, Facultat de Medicina, Universitat de Barcelona, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red (CIBER) sobre Enfermedades Neurodegenerativas (CIBERNED), Spain
| | - Ana Saavedra
- Departament de Biomedicina, Facultat de Medicina, Universitat de Barcelona, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red (CIBER) sobre Enfermedades Neurodegenerativas (CIBERNED), Spain.,Institut de Neurociències, Universitat de Barcelona, Catalonia, Spain
| | - Esther Pérez-Navarro
- Departament de Biomedicina, Facultat de Medicina, Universitat de Barcelona, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red (CIBER) sobre Enfermedades Neurodegenerativas (CIBERNED), Spain.,Institut de Neurociències, Universitat de Barcelona, Catalonia, Spain
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14
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May LM, Anggono V, Gooch HM, Jang SE, Matusica D, Kerbler GM, Meunier FA, Sah P, Coulson EJ. G-Protein-Coupled Inwardly Rectifying Potassium (GIRK) Channel Activation by the p75 Neurotrophin Receptor Is Required for Amyloid β Toxicity. Front Neurosci 2017; 11:455. [PMID: 28848381 PMCID: PMC5550722 DOI: 10.3389/fnins.2017.00455] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 07/26/2017] [Indexed: 02/05/2023] Open
Abstract
Alzheimer's disease is characterized by cognitive decline, neuronal degeneration, and the accumulation of amyloid-beta (Aβ). Although, the neurotoxic Aβ peptide is widely believed to trigger neuronal dysfunction and degeneration in Alzheimer's disease, the mechanism by which this occurs is poorly defined. Here we describe a novel, Aβ-triggered apoptotic pathway in which Aβ treatment leads to the upregulation of G-protein activated inwardly rectifying potassium (GIRK/Kir3) channels, causing potassium efflux from neurons and Aβ-mediated apoptosis. Although, GIRK channel activity is required for Aβ-induced neuronal degeneration, we show that it is not sufficient, with coincident signaling by the p75 neurotrophin receptor (p75NTR) also required for potassium efflux and cell death. Our results identify a novel role for GIRK channels in mediating apoptosis, and provide a previously missing mechanistic link between the excitotoxicity of Aβ and its ability to trigger cell death pathways, such as that mediated by p75NTR. We propose that this death-signaling pathway contributes to the dysfunction of neurons in Alzheimer's disease and is responsible for their eventual degeneration.
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Affiliation(s)
- Linda M May
- Queensland Brain Institute, University of QueenslandBrisbane, QLD, Australia
| | - Victor Anggono
- Queensland Brain Institute, University of QueenslandBrisbane, QLD, Australia.,Clem Jones Centre for Ageing Dementia Research, University of QueenslandBrisbane, QLD, Australia
| | - Helen M Gooch
- Queensland Brain Institute, University of QueenslandBrisbane, QLD, Australia
| | - Se E Jang
- Queensland Brain Institute, University of QueenslandBrisbane, QLD, Australia.,Clem Jones Centre for Ageing Dementia Research, University of QueenslandBrisbane, QLD, Australia
| | - Dusan Matusica
- Queensland Brain Institute, University of QueenslandBrisbane, QLD, Australia.,Centre for Neuroscience, College of Medicine and Public Health, Flinders UniversityAdelaide, SA, Australia
| | - Georg M Kerbler
- Queensland Brain Institute, University of QueenslandBrisbane, QLD, Australia
| | - Frederic A Meunier
- Queensland Brain Institute, University of QueenslandBrisbane, QLD, Australia.,Clem Jones Centre for Ageing Dementia Research, University of QueenslandBrisbane, QLD, Australia
| | - Pankaj Sah
- Queensland Brain Institute, University of QueenslandBrisbane, QLD, Australia
| | - Elizabeth J Coulson
- Queensland Brain Institute, University of QueenslandBrisbane, QLD, Australia.,Clem Jones Centre for Ageing Dementia Research, University of QueenslandBrisbane, QLD, Australia.,School of Biomedical Sciences, University of QueenslandBrisbane, QLD, Australia
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15
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O'Hern PJ, do Carmo G Gonçalves I, Brecht J, López Soto EJ, Simon J, Chapkis N, Lipscombe D, Kye MJ, Hart AC. Decreased microRNA levels lead to deleterious increases in neuronal M2 muscarinic receptors in Spinal Muscular Atrophy models. eLife 2017; 6. [PMID: 28463115 PMCID: PMC5413352 DOI: 10.7554/elife.20752] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 04/01/2017] [Indexed: 12/17/2022] Open
Abstract
Spinal Muscular Atrophy (SMA) is caused by diminished Survival of Motor Neuron (SMN) protein, leading to neuromuscular junction (NMJ) dysfunction and spinal motor neuron (MN) loss. Here, we report that reduced SMN function impacts the action of a pertinent microRNA and its mRNA target in MNs. Loss of the C. elegans SMN ortholog, SMN-1, causes NMJ defects. We found that increased levels of the C. elegans Gemin3 ortholog, MEL-46, ameliorates these defects. Increased MEL-46 levels also restored perturbed microRNA (miR-2) function in smn-1(lf) animals. We determined that miR-2 regulates expression of the C. elegans M2 muscarinic receptor (m2R) ortholog, GAR-2. GAR-2 loss ameliorated smn-1(lf) and mel-46(lf) synaptic defects. In an SMA mouse model, m2R levels were increased and pharmacological inhibition of m2R rescued MN process defects. Collectively, these results suggest decreased SMN leads to defective microRNA function via MEL-46 misregulation, followed by increased m2R expression, and neuronal dysfunction in SMA. DOI:http://dx.doi.org/10.7554/eLife.20752.001 Spinal muscular atrophy is a genetic disease that causes muscles to gradually weaken. In people with the disease, the nerve cells that control the movement of muscles – called motor neurons – deteriorate over time, hindering the person’s mobility and shortening their life expectancy. Spinal muscular atrophy is usually caused by genetic faults affecting a protein called SMN (which is short for “Survival of motor neuron”) and recent research suggested that disrupting this protein alters the function of short pieces of genetic material called microRNAs. However, the precise role that microRNAs play in the disease and their connection to the SMN protein was not clear. MicroRNAs interfere with the production of proteins by disrupting molecules called messenger RNAs, which are temporary strings of genetic code that carry the instructions for making protein. By disrupting messenger RNAs, microRNAs can delay or halt the production of specific proteins. This is an important part of the normal behavior of a cell, but disturbing the activity of microRNAs can lead to an unwanted rise or fall in crucial proteins. O’Hern et al. made use of engineered nematode worms and mice that share genetic features with spinal muscular atrophy patients, including disruption of the gene responsible for producing the SMN protein. These animal models of the disease were used to examine the relationship between decreased SMN levels and microRNAs in motor neurons. The experiments showed that reduced SMN activity affects a specific microRNA, which in turn causes motor neurons to produce more of a protein called m2R. This protein is a receptor for a molecule, called acetylcholine, which motor neurons use to send signals to muscle cells. Increased m2R may be detrimental to motor neurons. As such, O’Hern et al. decreased m2R protein activity to determine whether this could reverse the defects in motor neurons that arise in the animal models of the disease. Indeed, blocking this receptor rescued some of the defects seen in the animal models, supporting the link to spinal muscular atrophy. Several treatments that block m2R are already available to treat other conditions. As such, the next step is to determine whether these existing treatments are able to protect mice models of spinal muscular atrophy against muscle deterioration or increase their lifespan. If successful, this could open new avenues for the development of treatments in people. DOI:http://dx.doi.org/10.7554/eLife.20752.002
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Affiliation(s)
- Patrick J O'Hern
- Department of Neuroscience, Brown University, Providence, United States
| | | | - Johanna Brecht
- Institute of Human Genetics, University of Cologne, Cologne, Germany
| | | | - Jonah Simon
- Department of Neuroscience, Brown University, Providence, United States
| | - Natalie Chapkis
- Department of Neuroscience, Brown University, Providence, United States
| | - Diane Lipscombe
- Department of Neuroscience, Brown University, Providence, United States.,Brown Institute for Brain Science, Providence, United States
| | - Min Jeong Kye
- Institute of Human Genetics, University of Cologne, Cologne, Germany
| | - Anne C Hart
- Department of Neuroscience, Brown University, Providence, United States
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16
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Lin XY, Lai BQ, Zeng X, Che MT, Ling EA, Wu W, Zeng YS. Cell Transplantation and Neuroengineering Approach for Spinal Cord Injury Treatment: A Summary of Current Laboratory Findings and Review of Literature. Cell Transplant 2016; 25:1425-38. [DOI: 10.3727/096368916x690836] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Spinal cord injury (SCI) can cause severe traumatic injury to the central nervous system (CNS). Current therapeutic effects achieved for SCI in clinical medicine show that there is still a long way to go to reach the desired goal of full or significant functional recovery. In basic medical research, however, cell transplantation, gene therapy, application of cytokines, and biomaterial scaffolds have been widely used and investigated as treatments for SCI. All of these strategies when used separately would help rebuild, to some extent, the neural circuits in the lesion area of the spinal cord. In light of this, it is generally accepted that a combined treatment may be a more effective strategy. This review focuses primarily on our recent series of work on transplantation of Schwann cells and adult stem cells, and transplantation of stem cell-derived neural network scaffolds with functional synapses. Arising from this, an artificial neural network (an exogenous neuronal relay) has been designed and fabricated by us—a biomaterial scaffold implanted with Schwann cells modified by the neurotrophin-3 (NT-3) gene and adult stem cells modified with the TrkC (receptor of NT-3) gene. More importantly, experimental evidence suggests that the novel artificial network can integrate with the host tissue and serve as an exogenous neuronal relay for signal transfer and functional improvement of SCI.
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Affiliation(s)
- Xin-Yi Lin
- Key Laboratory for Stem Cells and Tissue Engineering (Sun Yat-sen University), Ministry of Education, Guangzhou, Guangdong, China
| | - Bi-Qin Lai
- Key Laboratory for Stem Cells and Tissue Engineering (Sun Yat-sen University), Ministry of Education, Guangzhou, Guangdong, China
| | - Xiang Zeng
- Key Laboratory for Stem Cells and Tissue Engineering (Sun Yat-sen University), Ministry of Education, Guangzhou, Guangdong, China
| | - Ming-Tian Che
- Key Laboratory for Stem Cells and Tissue Engineering (Sun Yat-sen University), Ministry of Education, Guangzhou, Guangdong, China
| | - Eng-Ang Ling
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Wutian Wu
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- State Key Laboratory of Brain and Cognitive Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
- Jinan University–Hong Kong University Joint Laboratory, GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China
| | - Yuan-Shan Zeng
- Key Laboratory for Stem Cells and Tissue Engineering (Sun Yat-sen University), Ministry of Education, Guangzhou, Guangdong, China
- Department of Histology and Embryology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Institute of Spinal Cord Injury, Sun Yat-sen University, Guangzhou, China
- Co-innovation Center of Neuroregeneration, Nantong, Jiangsu, China
- Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
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17
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Zeinieh M, Salehi A, Rajkumar V, Barker PA. p75NTR-dependent Rac1 activation requires receptor cleavage and activation of an NRAGE and NEDD9 signaling cascade. J Cell Sci 2016; 128:447-59. [PMID: 25472715 DOI: 10.1242/jcs.152173] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The p75 neurotrophin receptor (p75NTR, also known as tumor necrosis factor receptor superfamily member 16) is implicated in diverse cellular events, but fundamental aspects of its signaling mechanisms remain unclear. To address this, we have established a novel bioassay to characterize signaling cascades activated by p75NTR. We show that in COS7 cells, p75NTR expression causes a large increase in cell surface area that relies on the activation of Rac1, and we demonstrate that the p75NTR-dependent COS7 phenotype is dependent on ADAM17- and c-secretase-dependent cleavage of p75NTR and generation of the p75NTR intracellular domain (p75NTRICD). We show that the p75NTR adaptor protein NRAGE (also known as MAGED1) acts downstream of the p75NTRICD in this cascade and, through a yeast two-hybrid screen, identify NEDD9, a Cas family adaptor protein, as a novel NRAGE-binding partner that mediates p75NTR-dependent Rac1 activation and cell spreading. Our results demonstrate a crucial role for p75NTR cleavage in small GTPase activation and define a novel Rac1 activation pathway involving the p75NTRICD, NRAGE andNEDD9.
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18
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Duda J, Pötschke C, Liss B. Converging roles of ion channels, calcium, metabolic stress, and activity pattern of Substantia nigra dopaminergic neurons in health and Parkinson's disease. J Neurochem 2016; 139 Suppl 1:156-178. [PMID: 26865375 PMCID: PMC5095868 DOI: 10.1111/jnc.13572] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/03/2016] [Accepted: 02/05/2016] [Indexed: 12/18/2022]
Abstract
Dopamine‐releasing neurons within the Substantia nigra (SN DA) are particularly vulnerable to degeneration compared to other dopaminergic neurons. The age‐dependent, progressive loss of these neurons is a pathological hallmark of Parkinson's disease (PD), as the resulting loss of striatal dopamine causes its major movement‐related symptoms. SN DA neurons release dopamine from their axonal terminals within the dorsal striatum, and also from their cell bodies and dendrites within the midbrain in a calcium‐ and activity‐dependent manner. Their intrinsically generated and metabolically challenging activity is created and modulated by the orchestrated function of different ion channels and dopamine D2‐autoreceptors. Here, we review increasing evidence that the mechanisms that control activity patterns and calcium homeostasis of SN DA neurons are not only crucial for their dopamine release within a physiological range but also modulate their mitochondrial and lysosomal activity, their metabolic stress levels, and their vulnerability to degeneration in PD. Indeed, impaired calcium homeostasis, lysosomal and mitochondrial dysfunction, and metabolic stress in SN DA neurons represent central converging trigger factors for idiopathic and familial PD. We summarize double‐edged roles of ion channels, activity patterns, calcium homeostasis, and related feedback/feed‐forward signaling mechanisms in SN DA neurons for maintaining and modulating their physiological function, but also for contributing to their vulnerability in PD‐paradigms. We focus on the emerging roles of maintained neuronal activity and calcium homeostasis within a physiological bandwidth, and its modulation by PD‐triggers, as well as on bidirectional functions of voltage‐gated L‐type calcium channels and metabolically gated ATP‐sensitive potassium (K‐ATP) channels, and their probable interplay in health and PD.
We propose that SN DA neurons possess several feedback and feed‐forward mechanisms to protect and adapt their activity‐pattern and calcium‐homeostasis within a physiological bandwidth, and that PD‐trigger factors can narrow this bandwidth. We summarize roles of ion channels in this view, and findings documenting that both, reduced as well as elevated activity and associated calcium‐levels can trigger SN DA degeneration.
This article is part of a special issue on Parkinson disease.
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Affiliation(s)
- Johanna Duda
- Department of Applied Physiology, Ulm University, Ulm, Germany
| | | | - Birgit Liss
- Department of Applied Physiology, Ulm University, Ulm, Germany.
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19
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Gibon J, Buckley SM, Unsain N, Kaartinen V, Séguéla P, Barker PA. proBDNF and p75NTR Control Excitability and Persistent Firing of Cortical Pyramidal Neurons. J Neurosci 2015; 35:9741-53. [PMID: 26134656 PMCID: PMC6605143 DOI: 10.1523/jneurosci.4655-14.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 05/19/2015] [Accepted: 05/29/2015] [Indexed: 02/07/2023] Open
Abstract
Persistent firing of entorhinal cortex (EC) pyramidal neurons is a key component of working and spatial memory. We report here that a pro-brain-derived neurotrophic factor (proBDNF)-dependent p75NTR signaling pathway plays a major role in excitability and persistent activity of pyramidal neurons in layer V of the EC. Using electrophysiological recordings, we show that proBDNF suppresses persistent firing in entorhinal slices from wild-type mice but not from p75NTR-null mice. Conversely, function-blocking proBDNF antibodies enhance excitability of pyramidal neurons and facilitate their persistent firing, and acute exposure to function-blocking p75NTR antibodies results in enhanced firing activity of pyramidal neurons. Genetic deletion of p75NTR specifically in neurons or during adulthood also induces enhanced excitability and persistent activity, indicating that the proBDNF-p75NTR signaling cascade functions within adult neurons to inhibit pyramidal activity. Phosphatidylinositol 4,5-bisphosphate (PIP2)-sensitive transient receptor potential canonical channels play a critical role in mediating persistent firing in the EC and we hypothesized that proBDNF-dependent p75NTR activation regulates PIP2 levels. Accordingly, proBDNF decreases cholinergic calcium responses in cortical neurons and affects carbachol-induced depletion of PIP2. Further, we show that the modulation of persistent firing by proBDNF relies on a p75NTR-Rac1-PI4K pathway. The hypothesis that proBDNF and p75NTR maintain network homeostasis in the adult CNS was tested in vivo and we report that p75NTR-null mice show improvements in working memory but also display an increased propensity for severe seizures. We propose that the proBDNF-p75NTR axis controls pyramidal neuron excitability and persistent activity to balance EC performance with the risk of runaway activity. SIGNIFICANCE STATEMENT Persistent firing of entorhinal cortex (EC) pyramidal neurons is required for working memory. We report here that pro-brain-derived neurotrophic factor (proBDNF) activates p75NTR to induce a Rac1-dependent and phosphatidylinositol 4,5-bisphosphate-dependent signaling cascade that suppresses persistent activity. Conversely, using loss-of-function approaches, we find that endogenous proBDNF or p75NTR activation strongly decreases pyramidal neuron excitability and persistent firing, suggesting that a physiological role of this proBDNF-p75NTR cascade may be to regulate working memory in vivo. Consistent with this, mice rendered null for p75NTR during adulthood show improvements in working memory but also display an increased propensity for severe seizures. We propose that by attenuating EC network performance, the proBDNF-p75NTR signaling cascade reduces the probability of epileptogenesis.
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Affiliation(s)
- Julien Gibon
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada H3A2B4, and
| | - Shannon M Buckley
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada H3A2B4, and
| | - Nicolas Unsain
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada H3A2B4, and
| | - Vesa Kaartinen
- Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, Michigan 48109
| | - Philippe Séguéla
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada H3A2B4, and
| | - Philip A Barker
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada H3A2B4, and
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20
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Mayfield J, Blednov YA, Harris RA. Behavioral and Genetic Evidence for GIRK Channels in the CNS: Role in Physiology, Pathophysiology, and Drug Addiction. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:279-313. [PMID: 26422988 DOI: 10.1016/bs.irn.2015.05.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
G protein-coupled inwardly rectifying potassium (GIRK) channels are widely expressed throughout the brain and mediate the inhibitory effects of many neurotransmitters. As a result, these channels are important for normal CNS function and have also been implicated in Down syndrome, Parkinson's disease, psychiatric disorders, epilepsy, and drug addiction. Knockout mouse models have provided extensive insight into the significance of GIRK channels under these conditions. This review examines the behavioral and genetic evidence from animal models and genetic association studies in humans linking GIRK channels with CNS disorders. We further explore the possibility that subunit-selective modulators and other advanced research tools will be instrumental in establishing the role of individual GIRK subunits in drug addiction and other relevant CNS diseases and in potentially advancing treatment options for these disorders.
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Affiliation(s)
- Jody Mayfield
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, USA.
| | - Yuri A Blednov
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, USA
| | - R Adron Harris
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, USA
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21
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Wolfart J, Laker D. Homeostasis or channelopathy? Acquired cell type-specific ion channel changes in temporal lobe epilepsy and their antiepileptic potential. Front Physiol 2015; 6:168. [PMID: 26124723 PMCID: PMC4467176 DOI: 10.3389/fphys.2015.00168] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 05/19/2015] [Indexed: 01/16/2023] Open
Abstract
Neurons continuously adapt the expression and functionality of their ion channels. For example, exposed to chronic excitotoxicity, neurons homeostatically downscale their intrinsic excitability. In contrast, the “acquired channelopathy” hypothesis suggests that proepileptic channel characteristics develop during epilepsy. We review cell type-specific channel alterations under different epileptic conditions and discuss the potential of channels that undergo homeostatic adaptations, as targets for antiepileptic drugs (AEDs). Most of the relevant studies have been performed on temporal lobe epilepsy (TLE), a widespread AED-refractory, focal epilepsy. The TLE patients, who undergo epilepsy surgery, frequently display hippocampal sclerosis (HS), which is associated with degeneration of cornu ammonis subfield 1 pyramidal cells (CA1 PCs). Although the resected human tissue offers insights, controlled data largely stem from animal models simulating different aspects of TLE and other epilepsies. Most of the cell type-specific information is available for CA1 PCs and dentate gyrus granule cells (DG GCs). Between these two cell types, a dichotomy can be observed: while DG GCs acquire properties decreasing the intrinsic excitability (in TLE models and patients with HS), CA1 PCs develop channel characteristics increasing intrinsic excitability (in TLE models without HS only). However, thorough examination of data on these and other cell types reveals the coexistence of protective and permissive intrinsic plasticity within neurons. These mechanisms appear differentially regulated, depending on the cell type and seizure condition. Interestingly, the same channel molecules that are upregulated in DG GCs during HS-related TLE, appear as promising targets for future AEDs and gene therapies. Hence, GCs provide an example of homeostatic ion channel adaptation which can serve as a primer when designing novel anti-epileptic strategies.
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Affiliation(s)
- Jakob Wolfart
- Oscar Langendorff Institute of Physiology, University of Rostock Rostock, Germany
| | - Debora Laker
- Oscar Langendorff Institute of Physiology, University of Rostock Rostock, Germany
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22
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Krishnaraj RN, Kumari SSS, Mukhopadhyay SS. Antagonistic molecular interactions of photosynthetic pigments with molecular disease targets: a new approach to treat AD and ALS. J Recept Signal Transduct Res 2015; 36:67-71. [PMID: 26053508 DOI: 10.3109/10799893.2015.1024851] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS) are progressive neurodegenerative diseases that affect the neurons in the brain and the spinal cord. Neuroinflamation and apoptosis are key players in the progressive damage of the neurons in AD and ALS. Currently, there is no drug to offer complete cure for both these diseases. Riluzole is the only available drug that can prolong the life time of the ALS patients for nearly 3 months. Molecules that offer good HIT to the molecular targets of ALS will help to treat AD and ALS patients. P53 kinase receptor (4AT3), EphA4 (3CKH) and histone deacetylase (3SFF) are the promising disease targets of AD and ALS. This paper discusses on a new approach to combat neurodegenerative diseases using photosynthetic pigments. The docking studies were performed with the Autodock Vina algorithm to predict the binding of the natural pigments such as β carotene, chlorophyll a, chlorophyll b, phycoerythrin and phycocyanin on these targets. The β carotene, phycoerythrin and phycocyanin had higher binding energies indicating the antagonistic activity to the disease targets. These pigments serve as a potential therapeutic molecule to treat neuroinflammation and apoptosis in the AD and ALS patients.
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Affiliation(s)
- R Navanietha Krishnaraj
- a Department of Biotechnology , National Institute of Technology , Durgapur , West Bengal , India and
| | - S S Sreeja Kumari
- b CSIR - Central Electrochemical Research Institute , Karaikudi , Tamil Nadu , India
| | - Sudit Sekhar Mukhopadhyay
- a Department of Biotechnology , National Institute of Technology , Durgapur , West Bengal , India and
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Yee AG, Lee SM, Hunter MR, Glass M, Freestone PS, Lipski J. Effects of the Parkinsonian toxin MPP+ on electrophysiological properties of nigral dopaminergic neurons. Neurotoxicology 2014; 45:1-11. [DOI: 10.1016/j.neuro.2014.08.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 08/22/2014] [Accepted: 08/25/2014] [Indexed: 10/24/2022]
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Tian J, Tep C, Benedick A, Saidi N, Ryu JC, Kim ML, Sadasivan S, Oberdick J, Smeyne R, Zhu MX, Yoon SO. p75 regulates Purkinje cell firing by modulating SK channel activity through Rac1. J Biol Chem 2014; 289:31458-72. [PMID: 25253694 PMCID: PMC4223344 DOI: 10.1074/jbc.m114.589937] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 09/11/2014] [Indexed: 12/22/2022] Open
Abstract
p75 is expressed among Purkinje cells in the adult cerebellum, but its function has remained obscure. Here we report that p75 is involved in maintaining the frequency and regularity of spontaneous firing of Purkinje cells. The overall spontaneous firing activity of Purkinje cells was increased in p75(-/-) mice during the phasic firing period due to a longer firing period and accompanying reduction in silence period than in the wild type. We attribute these effects to a reduction in small conductance Ca(2+)-activated potassium (SK) channel activity in Purkinje cells from p75(-/-) mice compared with the wild type littermates. The mechanism by which p75 regulates SK channel activity appears to involve its ability to activate Rac1. In organotypic cultures of cerebellar slices, brain-derived neurotrophic factor increased RacGTP levels by activating p75 but not TrkB. These results correlate with a reduction in RacGTP levels in synaptosome fractions from the p75(-/-) cerebellum, but not in that from the cortex of the same animals, compared with wild type littermates. More importantly, we demonstrate that Rac1 modulates SK channel activity and firing patterns of Purkinje cells. Along with the finding that spine density was reduced in p75(-/-) cerebellum, these data suggest that p75 plays a role in maintaining normalcy of Purkinje cell firing in the cerebellum in part by activating Rac1 in synaptic compartments and modulating SK channels.
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Affiliation(s)
- JinBin Tian
- the Department of Neuroscience, Ohio State University, Columbus, Ohio 43210, the Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Chhavy Tep
- From the Department of Molecular and Cellular Biochemistry, the Biochemistry Program, and
| | - Alex Benedick
- From the Department of Molecular and Cellular Biochemistry
| | - Nabila Saidi
- From the Department of Molecular and Cellular Biochemistry
| | - Jae Cheon Ryu
- From the Department of Molecular and Cellular Biochemistry
| | - Mi Lyang Kim
- From the Department of Molecular and Cellular Biochemistry
| | - Shankar Sadasivan
- the Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, and
| | | | - Richard Smeyne
- the Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, and
| | - Michael X Zhu
- the Department of Neuroscience, Ohio State University, Columbus, Ohio 43210, the Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Sung Ok Yoon
- From the Department of Molecular and Cellular Biochemistry,
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25
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Larios JA, Jausoro I, Benitez ML, Bronfman FC, Marzolo MP. Neurotrophins regulate ApoER2 proteolysis through activation of the Trk signaling pathway. BMC Neurosci 2014; 15:108. [PMID: 25233900 PMCID: PMC4177048 DOI: 10.1186/1471-2202-15-108] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Accepted: 09/15/2014] [Indexed: 12/27/2022] Open
Abstract
Background ApoER2 and the neurotrophin receptors Trk and p75NTR are expressed in the CNS and regulate key functional aspects of neurons, including development, survival, and neuronal function. It is known that both ApoER2 and p75NTR are processed by metalloproteinases, followed by regulated intramembrane proteolysis. TrkA activation by nerve growth factor (NGF) increases the proteolytic processing of p75NTR mediated by ADAM17. Reelin induces the sheeding of ApoER2 ectodomain depending on metalloproteinase activity. However, it is not known if there is a common regulation mechanism for processing these receptors. Results We found that TrkA activation by NGF in PC12 cells induced ApoER2 processing, which was dependent on TrkA activation and metalloproteinases. NGF-induced ApoER2 proteolysis was independent of mitogen activated protein kinase activity and of phosphatidylinositol-3 kinase activity. In contrast, the basal proteolysis of ApoER2 increased when both kinases were pharmacologically inhibited. The ApoER2 ligand reelin regulated the proteolytic processing of its own receptor but not of p75NTR. Finally, in primary cortical neurons, which express both ApoER2 and TrkB, we found that the proteolysis of ApoER2 was also regulated by brain-derived growth factor (BDNF). Conclusions Our results highlight a novel relationship between neurotrophins and the reelin-ApoER2 system, suggesting that these two pathways might be linked to regulate brain development, neuronal survival, and some pathological conditions.
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Affiliation(s)
| | | | | | | | - Maria-Paz Marzolo
- Departamento de Biología Celular y Molecular, Laboratorio de Tráfico Intracelular y Señalización, Facultad de Ciencias Biológicas, Pontificia Universidad Católica, Alameda 340, Santiago 8320000, Chile.
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Green REA, Colella B, Maller JJ, Bayley M, Glazer J, Mikulis DJ. Scale and pattern of atrophy in the chronic stages of moderate-severe TBI. Front Hum Neurosci 2014; 8:67. [PMID: 24744712 PMCID: PMC3978360 DOI: 10.3389/fnhum.2014.00067] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Accepted: 01/27/2014] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Moderate-severe traumatic brain injury (TBI) is increasingly being understood as a progressive disorder, with growing evidence of reduced brain volume and white matter (WM) integrity as well as lesion expansion in the chronic phases of injury. The scale of these losses has yet to be investigated, and pattern of change across structures has received limited attention. OBJECTIVES (1) To measure the percentage of patients in our TBI sample showing atrophy from 5 to 20 months post-injury in the whole brain and in structures with known vulnerability to acute TBI, and (2) To examine relative vulnerability and patterns of volume loss across structures. METHODS Fifty-six TBI patients [complicated mild to severe, with mean Glasgow Coma Scale (GCS) in severe range] underwent MRI at, on average, 5 and 20 months post-injury; 12 healthy controls underwent MRI twice, with a mean gap between scans of 25.4 months. Mean monthly percent volume change was computed for whole brain (ventricle-to-brain ratio; VBR), corpus callosum (CC), and right and left hippocampi (HPC). RESULTS (1) Using a threshold of 2 z-scores below controls, 96% of patients showed atrophy across time points in at least one region; 75% showed atrophy in at least 3 of the 4 regions measured. (2) There were no significant differences in the proportion of patients who showed atrophy across structures. For those showing decline in VBR, there was a significant association with both the CC and the right HPC (P < 0.05 for both comparisons). There were also significant associations between those showing decline in (i) right and left HPC (P < 0.05); (ii) all combinations of genu, body and splenium of the CC (P < 0.05), and (iii) head and tail of the right HPC (P < 0.05 all sub-structure comparisons). CONCLUSIONS Atrophy in chronic TBI is robust, and the CC, right HPC and left HPC appear equally vulnerable. Significant associations between the right and left HPC, and within substructures of the CC and right HPC, raise the possibility of common mechanisms for these regions, including transneuronal degeneration. Given the 96% incidence rate of atrophy, a genetic explanation is unlikely to explain all findings. Multiple and possibly synergistic mechanisms may explain findings. Atrophy has been associated with poorer functional outcomes, but recent findings suggest there is potential to offset this. A better, understanding of the underlying mechanisms could permit targeted therapy enabling better long-term outcomes.
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Affiliation(s)
- Robin E. A. Green
- Cognitive Neurorehabilitation Sciences Laboratory, Research Department, Toronto Rehabilitation InstituteToronto, ON, Canada
- Department of Psychiatry, Faculty of Medicine, University of TorontoToronto, ON, Canada
| | - Brenda Colella
- Cognitive Neurorehabilitation Sciences Laboratory, Research Department, Toronto Rehabilitation InstituteToronto, ON, Canada
| | - Jerome J. Maller
- Brain Stimulation and Neuroimaging Laboratory, Monash Alfred Psychiatry Research Centre, Alfred HospitalMelbourne, VIC, Australia
| | - Mark Bayley
- Cognitive Neurorehabilitation Sciences Laboratory, Research Department, Toronto Rehabilitation InstituteToronto, ON, Canada
| | - Joanna Glazer
- Cognitive Neurorehabilitation Sciences Laboratory, Research Department, Toronto Rehabilitation InstituteToronto, ON, Canada
| | - David J. Mikulis
- fMRI Laboratory, Division of Applied and Interventional Research, Toronto Western Research InstituteToronto, ON, Canada
- Department of Medical Imaging, Faculty of Medicine, University of TorontoToronto, ON, Canada
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Kraemer BR, Yoon SO, Carter BD. The biological functions and signaling mechanisms of the p75 neurotrophin receptor. Handb Exp Pharmacol 2014; 220:121-164. [PMID: 24668472 DOI: 10.1007/978-3-642-45106-5_6] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The p75 neurotrophin receptor (p75(NTR)) regulates a wide range of cellular functions, including programmed cell death, axonal growth and degeneration, cell proliferation, myelination, and synaptic plasticity. The multiplicity of cellular functions governed by the receptor arises from the variety of ligands and co-receptors which associate with p75(NTR) and regulate its signaling. P75(NTR) promotes survival through interactions with Trk receptors, inhibits axonal regeneration via partnerships with Nogo receptor (Nogo-R) and Lingo-1, and promotes apoptosis through association with Sortilin. Signals downstream of these interactions are further modulated through regulated intramembrane proteolysis (RIP) of p75(NTR) and by interactions with numerous cytosolic partners. In this chapter, we discuss the intricate signaling mechanisms of p75(NTR), emphasizing how these signals are differentially regulated to mediate these diverse cellular functions.
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Affiliation(s)
- B R Kraemer
- Department of Biochemistry, Vanderbilt University School of Medicine, 625 Light Hall, Nashville, TN, 37232, USA
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Xia Y, Chen BY, Sun XL, Duan L, Gao GD, Wang JJ, Yung KKL, Chen LW. Presence of proNGF-sortilin signaling complex in nigral dopamine neurons and its variation in relation to aging, lactacystin and 6-OHDA insults. Int J Mol Sci 2013; 14:14085-104. [PMID: 23880857 PMCID: PMC3742233 DOI: 10.3390/ijms140714085] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 06/20/2013] [Accepted: 06/25/2013] [Indexed: 12/15/2022] Open
Abstract
Growing evidence has shown that proNGF-p75NTR-sortilin signaling might be a crucial factor in neurodegeneration, but it remains unclear if it may function in nigral neurons under aging and disease. The purpose of this study is to examine and quantify proNGF and sortilin expression in the substantia nigra and dynamic changes of aging in lactacystin and 6-hydroxydopamine (6-OHDA) rat models of Parkinson’s disease using immunofluorescence, electronic microscopy, western blot and FLIVO staining methods. The expression of proNGF and sortilin was abundantly and selectively identified in tyrosine hydroxylase (TH)-containing dopamine neurons in the substantia nigra. These proNGF/TH, sortilin/TH-positive neurons were densely distributed in the ventral tier, while they were less distributed in the dorsal tier, where calbindin-D28K-containing neurons were numerously located. A correlated decrease of proNGF, sortilin and TH was also detected during animal aging process. While increase of proNGF, sortilin and cleaved (active) caspase-3 expression was found in the lactacystin model, dynamic proNGF and sortilin changes along with dopamine neuronal loss were demonstrated in the substantia nigra of both the lactacystin and 6-OHDA models. This study has thus revealed the presence of the proNGF-sortilin signaling complex in nigral dopamine neurons and its response to aging, lactacystin and 6-OHDA insults, suggesting that it might contribute to neuronal apoptosis or neurodegeneration during pathogenesis and disease progression of Parkinson’s disease; the underlying mechanism and key signaling pathways involved warrant further investigation.
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Affiliation(s)
- Yi Xia
- Institute of Neurosciences, Fourth Military Medical University, Xi’an 710032, China; E-Mails: (Y.X.); (X.-L.S.); (L.D.)
- Department of Neurosurgery, Tangdou Hospital, Fourth Military Medical University, Xi’an 710038, China; E-Mail:
| | - Bei-Yu Chen
- Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi’an 710032, China; E-Mail:
| | - Xiao-Long Sun
- Institute of Neurosciences, Fourth Military Medical University, Xi’an 710032, China; E-Mails: (Y.X.); (X.-L.S.); (L.D.)
| | - Li Duan
- Institute of Neurosciences, Fourth Military Medical University, Xi’an 710032, China; E-Mails: (Y.X.); (X.-L.S.); (L.D.)
| | - Guo-Dong Gao
- Department of Neurosurgery, Tangdou Hospital, Fourth Military Medical University, Xi’an 710038, China; E-Mail:
| | - Jing-Jie Wang
- Department of Gastroenterology, Tangdou Hospital, Fourth Military Medical University, Xi’an 710038, China
- Authors to whom correspondence should be addressed; E-Mails: (J.-J.W.); (L.-W.C.); Tel.: +86-29-8477-6840 (L.-W.C.); Fax: +86-29-8324-6270 (L.-W.C.)
| | - Ken Kam-Lin Yung
- Department of Biology, Baptist University of Hong Kong, Hong Kong, China; E-Mail:
| | - Liang-Wei Chen
- Institute of Neurosciences, Fourth Military Medical University, Xi’an 710032, China; E-Mails: (Y.X.); (X.-L.S.); (L.D.)
- Authors to whom correspondence should be addressed; E-Mails: (J.-J.W.); (L.-W.C.); Tel.: +86-29-8477-6840 (L.-W.C.); Fax: +86-29-8324-6270 (L.-W.C.)
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Tian J, Tep C, Zhu MX, Yoon SO. Changes in Spontaneous firing patterns of cerebellar Purkinje cells in p75 knockout mice. CEREBELLUM (LONDON, ENGLAND) 2013; 12:300-3. [PMID: 23307658 PMCID: PMC3643992 DOI: 10.1007/s12311-012-0439-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The p75 neurotrophin receptor is highly expressed in the developing nervous system and is required for neuronal survival, growth, and synaptic transmission. In young mice, p75 is present in both granular cells and Purkinje cells of the cerebellum. Although p75 has been implicated in modulation of neuronal excitability in several neuronal types, whether and how it affects the excitability of cerebellar Purkinje neurons remained unclear. Using extracellular recordings of spontaneous firing of Purkinje neurons in cerebellar slices prepared from wild type and p75 knockout mice, we measured intrinsic firing properties in the presence of fast synaptic blockers of more than 200 Purkinje cells, each for a period of 5 min, for each genotype. We detected a significant increase in the mean firing frequency in p75(-/-) neurons comparing to the wild type littermates. Upon separating tonically firing from phasically firing cells, i.e., cells with firing pauses of longer than 300 ms, we observed that the change mainly arose from phasic firing cells and can be explained by an increase in the firing/silence ratio and a decrease in the number of long pauses during the 5-min recording period. We conclude that p75 plays an important role in regulating the firing-to-silence transition during the phasic firing period of the spontaneous firing of Purkinje cells. Thus, p75 exerts a modulatory function on Purkinje cell firing patterns, through which it may act as a key player in motor coordination and other cerebellum-regulated activities since Purkinje cells represent the sole neuronal output of the cerebellar cortex.
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Affiliation(s)
- Jinbin Tian
- Department of Neuroscience, The Ohio State University, Columbus, OH 43210
- Center for Molecular Neurobiology, The Ohio State University, Columbus, OH 43210
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Chhavy Tep
- Department of Molecular & Cellular Biochemistry, The Ohio State University, Columbus, OH 43210
- Center for Molecular Neurobiology, The Ohio State University, Columbus, OH 43210
| | - Michael X. Zhu
- Department of Neuroscience, The Ohio State University, Columbus, OH 43210
- Center for Molecular Neurobiology, The Ohio State University, Columbus, OH 43210
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Sung Ok Yoon
- Department of Molecular & Cellular Biochemistry, The Ohio State University, Columbus, OH 43210
- Center for Molecular Neurobiology, The Ohio State University, Columbus, OH 43210
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Ovsepian SV, Antyborzec I, O'Leary VB, Zaborszky L, Herms J, Oliver Dolly J. Neurotrophin receptor p75 mediates the uptake of the amyloid beta (Aβ) peptide, guiding it to lysosomes for degradation in basal forebrain cholinergic neurons. Brain Struct Funct 2013; 219:1527-41. [PMID: 23716278 DOI: 10.1007/s00429-013-0583-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Accepted: 05/15/2013] [Indexed: 12/12/2022]
Abstract
A fascinating yet perhaps overlooked trait of the p75 neurotrophin receptor (p75(NTR)) is its ability to bind ligands with no obvious neurotrophic function. Using cultured basal forebrain (BF) neurons, this study demonstrates selective internalization of amyloid β (Aβ) 1-42 in conjunction with p75(NTR) (labelled with IgG192-Cy3) by cholinergic cells. Active under resting conditions, this process was enhanced by high K(+) stimulation and was insensitive to inhibitors of regulated synaptic activity-tetrodotoxin or botulinum neurotoxins (BoNT type/A and/B). Blockade of sarco-endoplasmic reticulum (SERCA) Ca(2+) ATPase with thapsigargin and CPA or chelation of Ca(2+) with EGTA-AM strongly suppressed the endocytosis of p75(NTR), implicating the role of ER released Ca(2+). The uptake of IgG192-Cy3 was also reduced by T-type Ca(2+) channel blocker mibefradil but not Cd(2+), an indiscriminate blocker of high voltage-activated Ca(2+) currents. A strong co-localization of IgG192-Cy3 with late endosome (Rab7) or lysosome (Lamp1) qualifier proteins suggest these compartments as the primary destination for internalized IgG192 and Aβ. Selective uptake and labeling of BF cholinergic cells with IgG192-Cy3 injected into the prefrontal cortex was verified also in vivo. The significance of these findings in relation to Aβ clearance in the cerebral cortex and pathophysiology of Alzheimer's disease is discussed.
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Affiliation(s)
- Saak V Ovsepian
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Republic of Ireland,
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Matusica D, Skeldal S, Sykes AM, Palstra N, Sharma A, Coulson EJ. An intracellular domain fragment of the p75 neurotrophin receptor (p75(NTR)) enhances tropomyosin receptor kinase A (TrkA) receptor function. J Biol Chem 2013; 288:11144-54. [PMID: 23471969 PMCID: PMC3630867 DOI: 10.1074/jbc.m112.436469] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 02/17/2013] [Indexed: 11/06/2022] Open
Abstract
Facilitation of nerve growth factor (NGF) signaling by the p75 neurotrophin receptor (p75(NTR)) is critical for neuronal survival and differentiation. However, the interaction between p75(NTR) and TrkA receptors required for this activity is not understood. Here, we report that a specific 29-amino acid peptide derived from the intracellular domain fragment of p75(NTR) interacts with and potentiates binding of NGF to TrkA-expressing cells, leading to increased neurite outgrowth in sympathetic neurons as a result of enhanced Erk1/2 and Akt signaling. An endogenous intracellular domain fragment of p75(NTR) (p75(ICD)) containing these 29 amino acids is produced by regulated proteolysis of the full-length receptor. We demonstrate that generation of this fragment is a requirement for p75(NTR) to facilitate TrkA signaling in neurons and propose that the juxtamembrane region of p75(ICD) acts to cause a conformational change within the extracellular domain of TrkA. This finding provides new insight into the mechanism by which p75(NTR) and TrkA interact to enhance neurotrophic signaling.
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Affiliation(s)
- Dusan Matusica
- From the Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Sune Skeldal
- From the Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Alex M. Sykes
- From the Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Nickless Palstra
- From the Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Aanchal Sharma
- From the Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Elizabeth J. Coulson
- From the Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
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Imbalance of p75(NTR)/TrkB protein expression in Huntington's disease: implication for neuroprotective therapies. Cell Death Dis 2013; 4:e595. [PMID: 23598407 PMCID: PMC3641339 DOI: 10.1038/cddis.2013.116] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Neuroprotective therapies based on brain-derived neurotrophic factor (BDNF) administration have been proposed for Huntington's disease (HD) treatment. However, our group has recently reported reduced levels of TrkB in HD mouse models and HD human brain suggesting that besides a decrease on BDNF levels a reduction of TrkB expression could also contribute to diminished neurotrophic support in HD. BDNF can also bind to p75 neurotrophin receptor (p75NTR) modulating TrkB signaling. Therefore, in this study we have analyzed the levels of p75NTR in several HD models, as well as in HD human brain. Our data demonstrates a p75NTR/TrkB imbalance in the striatum of two different HD mouse models, HdhQ111/111 homozygous knockin mice and R6/1 mice that was also manifested in the putamen of HD patients. The imbalance between TrkB and p75NTR levels in a HD cellular model did not affect BDNF-mediated TrkB activation of prosurvival pathways but induced activation of apoptotic cascades as demonstrated by increased JNK phosphorylation. Moreover, BDNF failed to protect mutant huntingtin striatal cells transfected with p75NTR against NMDA-mediated excitotoxicity, which was associated with decreased Akt phosphorylation. Interestingly, lack of Akt activation following BDNF and NMDA treatment correlated with increased PP1 levels. Accordingly, pharmacological inhibition of PP1 by okadaic acid (OA) prevented mutant huntingtin striatal cell death induced by NMDA and BDNF. Altogether, our findings demonstrate that the p75NTR/TrkB imbalance induced by mutant huntingtin in striatal cells associated with the aberrant activity of PP1 disturbs BDNF neuroprotection likely contributing to increasing striatal vulnerability in HD. On the basis of this data we hypothesize that normalization of p75NTR and/or TrkB expression or their signaling will improve BDNF neuroprotective therapies in HD.
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Li PP, Zhou JJ, Meng M, Madhavan R, Peng HB. Reciprocal regulation of axonal Filopodia and outgrowth during neuromuscular junction development. PLoS One 2012; 7:e44759. [PMID: 22957106 PMCID: PMC3434160 DOI: 10.1371/journal.pone.0044759] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 08/06/2012] [Indexed: 01/01/2023] Open
Abstract
Background The assembly of the vertebrate neuromuscular junction (NMJ) is initiated when nerve and muscle first contact each other by filopodial processes which are thought to enable close interactions between the synaptic partners and facilitate synaptogenesis. We recently reported that embryonic Xenopus spinal neurons preferentially extended filopodia towards cocultured muscle cells and that basic fibroblast growth factor (bFGF) produced by muscle activated neuronal FGF receptor 1 (FGFR1) to induce filopodia and favor synaptogenesis. Intriguingly, in an earlier study we found that neurotrophins (NTs), a different set of target-derived factors that act through Trk receptor tyrosine kinases, promoted neuronal growth but hindered presynaptic differentiation and NMJ formation. Thus, here we investigated how bFGF- and NT-signals in neurons jointly elicit presynaptic changes during the earliest stages of NMJ development. Methodology/Principal Findings Whereas forced expression of wild-type TrkB in neurons reduced filopodial extension and triggered axonal outgrowth, expression of a mutant TrkB lacking the intracellular kinase domain enhanced filopodial growth and slowed axonal advance. Neurons overexpressing wild-type FGFR1 also displayed more filopodia than control neurons, in accord with our previous findings, and, notably, this elevation in filopodial density was suppressed when neurons were chronically treated from the beginning of the culture period with BDNF, the NT that specifically activates TrkB. Conversely, inhibition by BDNF of NMJ formation in nerve-muscle cocultures was partly reversed by the overexpression of bFGF in muscle. Conclusions Our results suggest that the balance between neuronal FGFR1- and TrkB-dependent filopodial assembly and axonal outgrowth regulates the establishment of incipient NMJs.
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Affiliation(s)
- Pan P. Li
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Jie J. Zhou
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Min Meng
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Raghavan Madhavan
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - H. Benjamin Peng
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- * E-mail:
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Nykjaer A, Willnow TE. Sortilin: a receptor to regulate neuronal viability and function. Trends Neurosci 2012; 35:261-70. [DOI: 10.1016/j.tins.2012.01.003] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 01/08/2012] [Accepted: 01/10/2012] [Indexed: 11/26/2022]
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Skeldal S, Matusica D, Nykjaer A, Coulson EJ. Proteolytic processing of the p75 neurotrophin receptor: A prerequisite for signalling?: Neuronal life, growth and death signalling are crucially regulated by intra-membrane proteolysis and trafficking of p75(NTR). Bioessays 2011; 33:614-25. [PMID: 21717487 DOI: 10.1002/bies.201100036] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The common neurotrophin receptor (p75(NTR) ) regulates various functions in the developing and adult nervous system. Cell survival, cell death, axonal and growth cone retraction, and regulation of the cell cycle can be regulated by p75(NTR) -mediated signals following activation by either mature or pro-neurotrophins and in combination with various co-receptors, including Trk receptors and sortilin. Here, we review the known functions of p75(NTR) by cell type, receptor-ligand combination, and whether regulated intra-membrane proteolysis of p75(NTR) is required for signalling. We highlight that the generation of the intracellular domain fragment of p75(NTR) is associated with many of the receptor functions, regardless of its ligand and co-receptor interactions.
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Affiliation(s)
- Sune Skeldal
- The Lundbeck Foundation Research Center MIND, Department of Medical Biochemistry, Aarhus University, Aarhus, Denmark.
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Emerging roles for G protein-gated inwardly rectifying potassium (GIRK) channels in health and disease. Nat Rev Neurosci 2010; 11:301-15. [PMID: 20389305 DOI: 10.1038/nrn2834] [Citation(s) in RCA: 456] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
G protein-gated inwardly rectifying potassium (GIRK) channels hyperpolarize neurons in response to activation of many different G protein-coupled receptors and thus control the excitability of neurons through GIRK-mediated self-inhibition, slow synaptic potentials and volume transmission. GIRK channel function and trafficking are highly dependent on the channel subunit composition. Pharmacological investigations of GIRK channels and studies in animal models suggest that GIRK activity has an important role in physiological responses, including pain perception and memory modulation. Moreover, abnormal GIRK function has been implicated in altering neuronal excitability and cell death, which may be important in the pathophysiology of diseases such as epilepsy, Down's syndrome, Parkinson's disease and drug addiction. GIRK channels may therefore prove to be a valuable new therapeutic target.
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Clarke JH, Emson PC, Irvine RF. Distribution and neuronal expression of phosphatidylinositol phosphate kinase IIgamma in the mouse brain. J Comp Neurol 2010; 517:296-312. [PMID: 19757494 PMCID: PMC2814081 DOI: 10.1002/cne.22161] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The role of cellular phosphatidylinositol 5-phosphate (PtdIns5P), as a signalling molecule or as a substrate for the production of small, compartmentalized pools of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], may be dependent on cell type and subcellular localization. PtdIns5P levels are primarily regulated by the PtdIns5P 4-kinases (type II PIP kinases or PIP4Ks), and we have investigated the expression and localization in the brain of the least-studied PIP4K isoform, PIP4Kγ. In situ hybridization and immunohistochemistry, using antisense oligonucleotide probes and a PIP4Kγ-specific antibody, revealed that this isoform has a restricted CNS expression profile. The use of antibodies to different cell markers showed that this expression is limited to neurons, particularly the cerebellar Purkinje cells, pyramidal cells of the hippocampus, large neuronal cell types in the cerebral cortex including pyramidal cells, and mitral cells in the olfactory bulb and is not expressed in cerebellar, hippocampal formation, or olfactory bulb granule cells. In neurons expressing this enzyme, PIP4Kγ has a vesicular distribution and shows partial colocalization with markers of cellular compartments of the endomembrane trafficking pathway. The PIP4Kγ isoform expression is established after day 7 of postnatal development. Overall, our data suggest that PIP4Kγ may have a role in neuron function, specifically in the regulation of vesicular transport, in specific regions of the developed brain. J. Comp. Neurol. 517:296–312, 2009. © 2009 Wiley-Liss, Inc.
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Affiliation(s)
- Jonathan H Clarke
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD United Kingdom.
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Diarra A, Geetha T, Potter P, Babu JR. Signaling of the neurotrophin receptor p75 in relation to Alzheimer's disease. Biochem Biophys Res Commun 2009; 390:352-6. [PMID: 19818333 DOI: 10.1016/j.bbrc.2009.09.116] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Accepted: 09/24/2009] [Indexed: 01/29/2023]
Abstract
The cellular mechanism of neuronal apoptosis in Alzheimer's disease (AD) is poorly understood. Many hypotheses have been put fourth to explain the underlying reason for neuro-degeneration in AD. Here, it is demonstrated that all neurotrophins that activated p75, without co-activation of the relevant Trk co-receptor, mediated apoptosis in hippocampal neurons. Thus, proneurotrophins and amyloid beta peptides (Abeta) can induce p75-mediated apoptosis in hippocampal neurons since they do not bind or activate Trk receptors. Based on the combined effects of aging, proneurotrophins, neurotrophins, and Abeta, a novel model of pathogenesis in AD is proposed. This mini-review explores the ligand and cell type based signaling pathways of the neurotrophin receptor p75 relating to Alzheimer's disease.
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Affiliation(s)
- Adama Diarra
- Department of Biochemistry, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ 85308, USA
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Coulson EJ, May LM, Sykes AM, Hamlin AS. The role of the p75 neurotrophin receptor in cholinergic dysfunction in Alzheimer's disease. Neuroscientist 2009; 15:317-23. [PMID: 19458382 DOI: 10.1177/1073858408331376] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Degeneration of basal forebrain cholinergic neurons is a common feature of Alzheimer's disease and is proposed to be an early and key event in the condition's etiology. This review discusses recent findings that strongly link the p75 neurotrophin receptor (p75(NTR)) to both cholinergic neuron degeneration and the production of toxic forms of amyloid-beta (Abeta), which is found deposited as amyloid plaques in the brains of Alzheimer's disease patients. Although elucidating the underlying molecular mechanisms and the clinical significance of these findings will require further experimentation, a number of possible scenarios and future research directions are presented.
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Affiliation(s)
- E J Coulson
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia.
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Haase G, Pettmann B, Raoul C, Henderson CE. Signaling by death receptors in the nervous system. Curr Opin Neurobiol 2009; 18:284-91. [PMID: 18725296 DOI: 10.1016/j.conb.2008.07.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Accepted: 07/21/2008] [Indexed: 12/12/2022]
Abstract
Cell death plays an important role both in shaping the developing nervous system and in neurological disease and traumatic injury. In spite of their name, death receptors can trigger either cell death or survival and growth. Recent studies implicate five death receptors--Fas/CD95, TNFR1 (tumor necrosis factor receptor-1), p75NTR (p75 neurotrophin receptor), DR4, and DR5 (death receptors-4 and -5)--in different aspects of neural development or degeneration. Their roles may be neuroprotective in models of Parkinson's disease, or pro-apoptotic in ALS and stroke. Such different outcomes probably reflect the diversity of transcriptional and posttranslational signaling pathways downstream of death receptors in neurons and glia.
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Affiliation(s)
- Georg Haase
- Developmental Biology Institute of Marseille-Luminy, IBDML, CNRS UMR 6216, Marseille Cedex 09, France
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Wong AW, Willingham M, Xiao J, Kilpatrick TJ, Murray SS. Neurotrophin receptor homolog-2 regulates nerve growth factor signaling. J Neurochem 2008; 106:1964-76. [PMID: 18624909 DOI: 10.1111/j.1471-4159.2008.05539.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The neurotrophin receptor homolog (NRH2) is closely related to the p75 neurotrophin receptor (p75NTR); however, its function and role in neurotrophin signaling are unclear. NRH2 does not bind to nerve growth factor (NGF), however, is able to form a receptor complex with tropomyosin-related kinase receptor A (TrkA) and to generate high-affinity NGF binding sites. Despite this, the mechanisms underpinning the interaction between NRH2 and TrkA remain unknown. Here, we identify that the intracellular domain of NRH2 is required to form an association with TrkA. Our data suggest extensive intracellular interaction between NRH2 and TrkA, as either the juxtamembrane or death domain regions of NRH2 are sufficient for interaction with TrkA. In addition, we demonstrate that TrkA signaling is dramatically influenced by the co-expression of NRH2. Importantly, NRH2 did not influence all downstream TrkA signaling pathways, but rather exerted a specific effect, enhancing src homology 2 domain-containing transforming protein (Shc) activation. Moreover, downstream of Shc, the co-expression of NRH2 resulted in TrkA specifically modulating mitogen-activated protein kinase pathway activation, but not the phosphatidylinositol 3-kinase/Akt pathway. These results indicate that NRH2 utilizes intracellular mechanisms to not only regulate NGF binding to TrkA, but also specifically modulate TrkA receptor signaling, thus adding further layers of complexity and specificity to neurotrophin signaling.
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Affiliation(s)
- Agnes W Wong
- Neurotrophin Signaling Laboratory, The Centre for Neuroscience, The University of Melbourne, Victoria, Australia
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Abstract
Alzheimer's disease is characterized by the accumulation of neurotoxic amyloidogenic peptide Abeta, degeneration of the cholinergic innervation to the hippocampus (the septohippocampal pathway), and progressive impairment of cognitive function, particularly memory. Abeta is a ligand for the p75 neurotrophin receptor (p75(NTR)), which is best known for mediating neuronal death and has been consistently linked to the pathology of Alzheimer's disease. Here we examined whether p75(NTR) is required for Abeta-mediated effects. Treatment of wild-type but not p75(NTR)-deficient embryonic mouse hippocampal neurons with human Abeta(1-42) peptide induced significant cell death. Furthermore, injection of Abeta(1-42) into the hippocampus of adult mice resulted in significant degeneration of wild-type but not p75(NTR)-deficient cholinergic basal forebrain neurons, indicating that the latter are resistant to Abeta-induced toxicity. We also found that neuronal death correlated with Abeta(1-42) peptide-stimulated accumulation of the death-inducing p75(NTR) C-terminal fragment generated by extracellular metalloprotease cleavage of full-length p75(NTR). Although neuronal death was prevented in the presence of the metalloprotease inhibitor TAPI-2 (tumor necrosis factor-alpha protease inhibitor-2), Abeta(1-42)-induced accumulation of the C-terminal fragment resulted from inhibition of gamma-secretase activity. These results provide a novel mechanism to explain the early and characteristic loss of cholinergic neurons in the septohippocampal pathway that occurs in Alzheimer's disease.
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