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Bondarenko V, Chen Q, Tillman TS, Xu Y, Tang P. Unconventional PDZ Recognition Revealed in α7 nAChR-PICK1 Complexes. ACS Chem Neurosci 2024; 15:2070-2079. [PMID: 38691676 PMCID: PMC11099923 DOI: 10.1021/acschemneuro.4c00138] [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: 03/05/2024] [Revised: 04/16/2024] [Accepted: 04/19/2024] [Indexed: 05/03/2024] Open
Abstract
PDZ domains are modular domains that conventionally bind to C terminal or internal motifs of target proteins to control cellular functions through the regulation of protein complex assemblies. Almost all reported structures of PDZ-target protein complexes rely on fragments or peptides as target proteins. No intact target protein complexed with PDZ was structurally characterized. In this study, we used NMR spectroscopy and other biochemistry and biophysics tools to uncover insights into structural coupling between the PDZ domain of protein interacting with C-kinase 1 (PICK1) and α7 nicotinic acetylcholine receptors (α7 nAChR). Notably, the intracellular domains of both α7 nAChR and PICK1 PDZ exhibit a high degree of plasticity in their coupling. Specifically, the MA helix of α7 nAChR interacts with residues lining the canonical binding site of the PICK1 PDZ, while flexible loops also engage in protein-protein interactions. Both hydrophobic and electrostatic interactions mediate the coupling. Overall, the resulting structure of the α7 nAChR-PICK1 complex reveals an unconventional PDZ binding mode, significantly expanding the repertoire of functionally important PDZ interactions.
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Affiliation(s)
- Vasyl Bondarenko
- Depatment
of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Qiang Chen
- Depatment
of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Tommy S. Tillman
- Depatment
of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Yan Xu
- Depatment
of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department
of Structural Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department
of Pharmacology and Chemical Biology, University
of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department
of Physics and Astronomy, University of
Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Pei Tang
- Depatment
of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department
of Pharmacology and Chemical Biology, University
of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department
of Computational and Systems Biology, University
of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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2
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The neuroprotective effects of activated α7 nicotinic acetylcholine receptor against mutant copper-zinc superoxide dismutase 1-mediated toxicity. Sci Rep 2020; 10:22157. [PMID: 33335227 PMCID: PMC7746719 DOI: 10.1038/s41598-020-79189-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 12/02/2020] [Indexed: 11/08/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the selective and progressive loss of motor neurons. Although many drugs have entered clinical trials, few have shown effectiveness in the treatment of ALS. Other studies have shown that the stimulation of α7 nicotinic acetylcholine receptor (nAChR) can have neuroprotective effects in some models of neurodegenerative disease, as well as prevent glutamate-induced motor neuronal death. However, the effect of α7 nAChR agonists on ALS-associated mutant copper-zinc superoxide dismutase 1 (SOD1) aggregates in motor neurons remains unclear. In the present study, we examined whether α7 nAChR activation had a neuroprotective effect against SOD1G85R-induced toxicity in a cellular model for ALS. We found that α7 nAChR activation by PNU282987, a selective agonist of α7 nAChR, exhibited significant neuroprotective effects against SOD1G85R-induced toxicity via the reduction of intracellular protein aggregates. This reduction also correlated with the activation of autophagy through the AMP-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR) signaling pathway. Furthermore, the activation of α7 nAChRs was found to increase the biogenesis of lysosomes by inducing translocation of the transcription factor EB (TFEB) into the nucleus. These results support the therapeutic potential of α7 nAChR activation in diseases that are characterized by SOD1G85R aggregates, such as ALS.
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3
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Status of antiviral therapeutics against rabies virus and related emerging lyssaviruses. Curr Opin Virol 2019; 35:1-13. [PMID: 30753961 DOI: 10.1016/j.coviro.2018.12.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 12/19/2022]
Abstract
Rabies virus (RABV) constitutes a major social and economic burden associated with 60 000 deaths annually worldwide. Although pre-exposure and post-exposure treatment options are available, they are efficacious only when initiated before the onset of clinical symptoms. Aggravating the problem, the current RABV vaccine does not cross-protect against the emerging zoonotic phylogroup II lyssaviruses. A requirement for an uninterrupted cold chain and high cost of the immunoglobulin component of rabies prophylaxis generate an unmet need for the development of RABV-specific antivirals. We discuss desirable anti-RABV drug profiles, past efforts to address the problem and inhibitor candidates identified, and examine how the rapidly expanding structural insight into RABV protein organization has illuminated novel druggable target candidates and paved the way to structure-aided drug optimization. Special emphasis is given to the viral RNA-dependent RNA polymerase complex as a promising target for direct-acting broad-spectrum RABV inhibitors.
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4
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Kaur J, Rauti R, Nistri A. Nicotine‐mediated neuroprotection of rat spinal networks against excitotoxicity. Eur J Neurosci 2018; 47:1353-1374. [DOI: 10.1111/ejn.13950] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 03/19/2018] [Accepted: 04/10/2018] [Indexed: 12/16/2022]
Affiliation(s)
- Jaspreet Kaur
- Department of NeuroscienceInternational School for Advanced Studies (SISSA) Trieste Italy
- Jaspreet Kaur, Institute of Neurosciences of Timone (IMAPATH Team) ‐ CERIMEDUMR 7289Aix‐Marseille University 27, boulevard Jean Moulin Marseille Cedex 05 13385 France
| | - Rossana Rauti
- Department of NeuroscienceInternational School for Advanced Studies (SISSA) Trieste Italy
| | - Andrea Nistri
- Department of NeuroscienceInternational School for Advanced Studies (SISSA) Trieste Italy
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5
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Dart AE, Worth DC, Muir G, Chandra A, Morris JD, McKee C, Verrill C, Bryant RJ, Gordon-Weeks PR. The drebrin/EB3 pathway drives invasive activity in prostate cancer. Oncogene 2017; 36:4111-4123. [PMID: 28319065 PMCID: PMC5537610 DOI: 10.1038/onc.2017.45] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 01/13/2017] [Accepted: 02/02/2017] [Indexed: 02/06/2023]
Abstract
Prostate cancer is the most common cancer in men and the metastatic form of the disease is incurable. We show here that the drebrin/EB3 pathway, which co-ordinates dynamic microtubule/actin filament interactions underlying cell shape changes in response to guidance cues, plays a role in prostate cancer cell invasion. Drebrin expression is restricted to basal epithelial cells in benign human prostate but is upregulated in luminal epithelial cells in foci of prostatic malignancy. Drebrin is also upregulated in human prostate cancer cell lines and co-localizes with actin filaments and dynamic microtubules in filopodia of pseudopods of invading cells under a chemotactic gradient of the chemokine CXCL12. Disruption of the drebrin/EB3 pathway using BTP2, a small molecule inhibitor of drebrin binding to actin filaments, reduced the invasion of prostate cancer cell lines in 3D in vitro assays. Furthermore, gain- or loss-of-function of drebrin or EB3 by over-expression or siRNA-mediated knockdown increases or decreases invasion of prostate cancer cell lines in 3D in vitro assays, respectively. Finally, expression of a dominant-negative construct that competes with EB3 binding to drebrin, also inhibited invasion of prostate cancer cell lines in 3D in vitro assays. Our findings show that co-ordination of dynamic microtubules and actin filaments by the drebrin/EB3 pathway drives prostate cancer cell invasion and is therefore implicated in disease progression.
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Affiliation(s)
- A E Dart
- The MRC Centre for Developmental Neurobiology, King's College London, New Hunts House, Guy's Campus, London, UK
| | - D C Worth
- The MRC Centre for Developmental Neurobiology, King's College London, New Hunts House, Guy's Campus, London, UK
| | - G Muir
- Urology, King's College Hospital, London, UK
| | - A Chandra
- Cellular Pathology, 2nd floor North Wing, St. Thomas' Hospital, London, UK
| | - J D Morris
- Division of Cancer Studies, New Hunt's House, Guy's Campus, King's College London, London, UK
| | - C McKee
- Oxford Institute for Radiation Oncology, Churchill Hospital, University of Oxford, Oxford, UK
| | - C Verrill
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
| | - R J Bryant
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
| | - P R Gordon-Weeks
- The MRC Centre for Developmental Neurobiology, King's College London, New Hunts House, Guy's Campus, London, UK
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6
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Gonzalez-Islas C, Garcia-Bereguiain MA, O'Flaherty B, Wenner P. Tonic nicotinic transmission enhances spinal GABAergic presynaptic release and the frequency of spontaneous network activity. Dev Neurobiol 2015; 76:298-312. [PMID: 26061781 DOI: 10.1002/dneu.22315] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 05/26/2015] [Accepted: 06/05/2015] [Indexed: 01/16/2023]
Abstract
Synaptically driven spontaneous network activity (SNA) is observed in virtually all developing networks. Recurrently connected spinal circuits express SNA, which drives fetal movements during a period of development when GABA is depolarizing and excitatory. Blockade of nicotinic acetylcholine receptor (nAChR) activation impairs the expression of SNA and the development of the motor system. It is mechanistically unclear how nicotinic transmission influences SNA, and in this study we tested several mechanisms that could underlie the regulation of SNA by nAChRs. We find evidence that is consistent with our previous work suggesting that cholinergically driven Renshaw cells can initiate episodes of SNA. While Renshaw cells receive strong nicotinic synaptic input, we see very little evidence suggesting other spinal interneurons or motoneurons receive nicotinic input. Rather, we found that nAChR activation tonically enhanced evoked and spontaneous presynaptic release of GABA in the embryonic spinal cord. Enhanced spontaneous and/or evoked release could contribute to increased SNA frequency. Finally, our study suggests that blockade of nAChRs can reduce the frequency of SNA by reducing probability of GABAergic release. This result suggests that the baseline frequency of SNA is maintained through elevated GABA release driven by tonically active nAChRs. Nicotinic receptors regulate GABAergic transmission and SNA, which are critically important for the proper development of the embryonic network. Therefore, our results provide a better mechanistic framework for understanding the motor consequences of fetal nicotine exposure.
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Affiliation(s)
- Carlos Gonzalez-Islas
- Department of Physiology, Emory University, School of Medicine, Whitehead Bldg, Room 601, Atlanta, Georgia, 30322
| | | | - Brendan O'Flaherty
- Department of Physiology, Emory University, School of Medicine, Whitehead Bldg, Room 601, Atlanta, Georgia, 30322
| | - Peter Wenner
- Department of Physiology, Emory University, School of Medicine, Whitehead Bldg, Room 601, Atlanta, Georgia, 30322
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7
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Cholinergic systems mediate action from movement to higher consciousness. Behav Brain Res 2011; 221:488-98. [DOI: 10.1016/j.bbr.2009.12.046] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 12/26/2009] [Indexed: 02/06/2023]
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8
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Gao B, Hierl M, Clarkin K, Juan T, Nguyen H, van der Valk M, Deng H, Guo W, Lehto SG, Matson D, McDermott JS, Knop J, Gaida K, Cao L, Waldon D, Albrecht BK, Boezio AA, Copeland KW, Harmange JC, Springer SK, Malmberg AB, McDonough SI. Pharmacological effects of nonselective and subtype-selective nicotinic acetylcholine receptor agonists in animal models of persistent pain. Pain 2010; 149:33-49. [DOI: 10.1016/j.pain.2010.01.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 12/16/2009] [Accepted: 01/11/2010] [Indexed: 12/20/2022]
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9
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Hotta K, Bazartseren B, Kaku Y, Noguchi A, Okutani A, Inoue S, Yamada A. Effect of cellular cholesterol depletion on rabies virus infection. Virus Res 2009; 139:85-90. [DOI: 10.1016/j.virusres.2008.10.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 10/18/2008] [Accepted: 10/18/2008] [Indexed: 12/11/2022]
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10
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Millar NS, Harkness PC. Assembly and trafficking of nicotinic acetylcholine receptors (Review). Mol Membr Biol 2008; 25:279-92. [PMID: 18446614 DOI: 10.1080/09687680802035675] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are members of an extensive super-family of neurotransmitter-gated ion channels. In humans, nAChRs are expressed within the nervous system and at the neuromuscular junction and are important targets for pharmaceutical drug discovery. They are also the site of action for neuroactive pesticides in insects and other invertebrates. Nicotinic receptors are complex pentameric transmembrane proteins which are assembled from a large family of subunits; seventeen nAChR subunits (alpha1-alpha10, beta1-beta4, gamma, delta and epsilon) have been identified in vertebrate species. This review will discuss nAChR subunit diversity and factors influencing receptor assembly and trafficking.
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Affiliation(s)
- Neil S Millar
- Department of Pharmacology, University College London, London, UK.
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11
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Hancock ML, Canetta SE, Role LW, Talmage DA. Presynaptic type III neuregulin1-ErbB signaling targets {alpha}7 nicotinic acetylcholine receptors to axons. ACTA ACUST UNITED AC 2008; 181:511-21. [PMID: 18458158 PMCID: PMC2364689 DOI: 10.1083/jcb.200710037] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Type III Neuregulin1 (Nrg1) isoforms are membrane-tethered proteins capable of participating in bidirectional juxtacrine signaling. Neuronal nicotinic acetylcholine receptors (nAChRs), which can modulate the release of a rich array of neurotransmitters, are differentially targeted to presynaptic sites. We demonstrate that Type III Nrg1 back signaling regulates the surface expression of α7 nAChRs along axons of sensory neurons. Stimulation of Type III Nrg1 back signaling induces an increase in axonal surface α7 nAChRs, which results from a redistribution of preexisting intracellular pools of α7 rather than from increased protein synthesis. We also demonstrate that Type III Nrg1 back signaling activates a phosphatidylinositol 3-kinase signaling pathway and that activation of this pathway is required for the insertion of preexisting α7 nAChRs into the axonal plasma membrane. These findings, in conjunction with prior results establishing that Type III Nrg1 back signaling controls gene transcription, demonstrate that Type III Nrg1 back signaling can regulate both short-and long-term changes in neuronal function.
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Affiliation(s)
- Melissa L Hancock
- Integrated Program in Cellular, Molecular and Biophysical Studies, Columbia University, New York, NY 10032, USA
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12
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Baenziger JE, Ryan SE, Goodreid MM, Vuong NQ, Sturgeon RM, daCosta CJB. Lipid Composition Alters Drug Action at the Nicotinic Acetylcholine Receptor. Mol Pharmacol 2007; 73:880-90. [DOI: 10.1124/mol.107.039008] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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13
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Baer K, Bürli T, Huh KH, Wiesner A, Erb-Vögtli S, Göckeritz-Dujmovic D, Moransard M, Nishimune A, Rees MI, Henley JM, Fritschy JM, Fuhrer C. PICK1 interacts with alpha7 neuronal nicotinic acetylcholine receptors and controls their clustering. Mol Cell Neurosci 2007; 35:339-55. [PMID: 17467288 PMCID: PMC3310904 DOI: 10.1016/j.mcn.2007.03.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2006] [Revised: 03/13/2007] [Accepted: 03/19/2007] [Indexed: 01/28/2023] Open
Abstract
Central to synaptic function are protein scaffolds associated with neurotransmitter receptors. Alpha7 neuronal nicotinic acetylcholine receptors (nAChRs) modulate network activity, neuronal survival and cognitive processes in the CNS, but protein scaffolds that interact with these receptors are unknown. Here we show that the PDZ-domain containing protein PICK1 binds to alpha7 nAChRs and plays a role in their clustering. PICK1 interacted with the alpha7 cytoplasmic loop in yeast in a PDZ-dependent way, and the interaction was confirmed in recombinant pull-down experiments and by co-precipitation of native proteins. Some alpha7 and PICK1 clusters were adjacent at the surface of SH-SY5Y cells and GABAergic interneurons in hippocampal cultures. Expression of PICK1 caused decreased alpha7 clustering on the surface of the interneurons in a PDZ-dependent way. These data show that PICK1 negatively regulates surface clustering of alpha7 nAChRs on hippocampal interneurons, which may be important in inhibitory functions of alpha7 in the hippocampus.
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Affiliation(s)
- Kristin Baer
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
- School of Medicine, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK
| | - Thomas Bürli
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Kyung-Hye Huh
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Andreas Wiesner
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Susanne Erb-Vögtli
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Dubravka Göckeritz-Dujmovic
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Martijn Moransard
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Atsushi Nishimune
- Medical Research Council Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, Bristol BS8 1TD, UK
| | - Mark I. Rees
- School of Medicine, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK
| | - Jeremy M. Henley
- Medical Research Council Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, Bristol BS8 1TD, UK
| | - Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Christian Fuhrer
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
- Corresponding author. Fax: +41 1 635 33 03.
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14
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Dmitrieva NA, Strang CE, Keyser KT. Expression of alpha 7 nicotinic acetylcholine receptors by bipolar, amacrine, and ganglion cells of the rabbit retina. J Histochem Cytochem 2006; 55:461-76. [PMID: 17189521 DOI: 10.1369/jhc.6a7116.2006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cholinergic agents affect the light responses of many ganglion cells (GCs) in the mammalian retina by activating nicotinic acetylcholine receptors (nAChRs). Whereas retinal neurons that express beta2 subunit-containing nAChRs have been characterized in the rabbit retina, expression patterns of other nAChR subtypes remain unclear. Therefore, we evaluated the expression of alpha7 nAChRs in retinal neurons by means of single-, double-, and triple-label immunohistochemistry. Our data demonstrate that, in the rabbit retina, several types of bipolar cells, amacrine cells, and cells in the GC layer express alpha7 nAChRs. At least three different populations of cone bipolar cells exhibited alpha7 labeling, whereas glycine-immunoreactive amacrine cells comprised the majority of alpha7-positive amacrine cells. Some GABAergic amacrine cells also displayed alpha7 immunoreactivity; alpha7 labeling was never detected in rod bipolar cells or rod amacrine cells (AII amacrine cells). Our data suggest that activation of alpha7 nAChRs by acetylcholine (ACh) or choline may affect glutamate release from several types of cone bipolar cells, modulating GC responses. ACh-induced excitation of inhibitory amacrine cells might cause either inhibition or disinhibition of other amacrine and GC circuits. Finally, ACh may act on alpha7 nAChRs expressed by GCs themselves.
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Affiliation(s)
- Nina A Dmitrieva
- Vision Science Research Center, The University of Alabama at Birmingham, WORB, 626 Birmingham, AL 35294-4390, USA
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15
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Morley BJ. Nicotinic cholinergic intercellular communication: implications for the developing auditory system. Hear Res 2005; 206:74-88. [PMID: 16081000 DOI: 10.1016/j.heares.2005.02.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2004] [Accepted: 02/24/2005] [Indexed: 02/02/2023]
Abstract
In this paper, research on the temporal and spatial distribution of cholinergic-related molecules in the lower auditory brainstem, with an emphasis on nicotinic acetylcholine receptors (nAChRs), is reviewed. The possible functions of acetylcholine (ACh) in driving selective auditory neurons before the onset of hearing, inducing glutamate receptor gene expression, synaptogenesis, differentiation, and cell survival are discussed. Experiments conducted in other neuronal and non-neuronal systems are drawn on extensively to discuss putative functions of ACh and nAChRs. Data from other systems may provide insight into the functions of ACh and nAChRs in auditory processing. The mismatch of presynaptic and postsynaptic markers and novel endogenous agonists of nAChRs are discussed in the context of non-classical interneuronal communication. The molecular mechanism that may underlie the many functions of ACh and its agonists is the regulation of intracellular calcium through nAChRs. The possible reorganization that may take place in the auditory system by the exposure to nicotine during critical developmental periods is also briefly considered.
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Affiliation(s)
- Barbara J Morley
- Boys Town National Research Hospital, Neurochemistry Laboratory, 555 North 30th Street, Omaha, NE 68131, USA.
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16
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Turner TJ. Nicotine enhancement of dopamine release by a calcium-dependent increase in the size of the readily releasable pool of synaptic vesicles. J Neurosci 2005; 24:11328-36. [PMID: 15601939 PMCID: PMC6730353 DOI: 10.1523/jneurosci.1559-04.2004] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A major factor underlying compulsive tobacco use is nicotine-induced modulation of dopamine release in the mesolimbic reward pathway (Wise and Rompre, 1989). An established biochemical mechanism for nicotine-enhanced dopamine release is by activating presynaptic nicotinic acetylcholine receptors (nAChRs) (Wonnacott, 1997). Prolonged application of 10(-7) to 10(-5) m nicotine to striatal synaptosomes promoted a sustained efflux of [3H]dopamine. This nicotine effect was mediated by non-alpha7 nAChRs, because it was blocked by 5 mum mecamylamine but was resistant to 100 nm alpha-bungarotoxin (alphaBgTx). Dopamine release was diminished by omitting Na+ or by applying peptide calcium channel blockers, indicating that nAChRs trigger release by depolarizing the nerve terminals. However, because alpha7 receptors rapidly desensitize in the continuous presence of agonists, a repetitive stimulation protocol was used to evaluate the possible significance of desensitization. This protocol produced a transient increase in [3H]dopamine released by depolarization and a significant increase in the response to hypertonic solutions that measure the size of the readily releasable pool (RRP) of synaptic vesicles. The nicotine-induced increase in the size of the readily releasable pool was blocked by alphaBgTx and by the calmodulin antagonist calmidazolium, suggesting that Ca2+ entry through alpha7 nAChRs specifically enhances synaptic vesicle mobilization at dopamine terminals. Thus, nicotine enhances dopamine release by two complementary actions mediated by discrete nAChR subtypes and suggest that the alpha7 nAChR-mediated pathway is tightly and specifically coupled to refilling of the RRP of vesicles in dopamine terminals.
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Affiliation(s)
- Timothy J Turner
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
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17
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Severance EG, Cuevas J. Distribution and synaptic localization of nicotinic acetylcholine receptors containing a novel α7 subunit isoform in embryonic rat cortical neurons. Neurosci Lett 2004; 372:104-9. [PMID: 15531097 DOI: 10.1016/j.neulet.2004.09.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2004] [Revised: 08/27/2004] [Accepted: 09/09/2004] [Indexed: 10/26/2022]
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) containing the alpha7 subunit isoform, alpha7-2 (alpha7-2-nAChRs), have previously been found to form functional homopentameric channels that desensitize slowly and bind alpha-bungarotoxin (alphaBgt) in a rapidly reversible manner. This isoform incorporates a novel cassette exon in the extracellular, ligand binding domain of the native receptor. Although this alpha7 subunit isoform has been detected in peripheral ganglia as well as in the central nervous system, little is known about the cellular function of alpha7-2-nAChRs. Co-localization immunocytochemical studies were conducted in an embryonic rat cultured cortical neuron model using a polyclonal antibody (Ab 87) raised against the amino acid sequence of the cassette exon, in combination with (1) an antibody that recognizes all known alpha7-nAChRs, (2) alphaBgt, and (3) antibodies directed against multiple cellular markers. The pattern of alpha7-2-nAChR expression was consistent with alpha7 staining in general, based on co-distribution of mAb319 and alphaBgt signals. However, alpha7-2-nAChRs clearly represent a distinct subset of alpha7 receptors. The alpha7-2-nAChR subtype was found throughout the cell-soma surface and was localized to a subpopulation of dendrites. Punctate staining characteristic of synaptic alpha7-2 targeting was observed at post-synaptic densities and intermittently at pre-synaptic locations. The alpha7-2 subunit was expressed on both GABAergic and non-GABAergic neurons. These studies reveal that receptors containing the alpha7-2 subunit constitute a subpopulation of alpha7-nAChRs and likely participate in cell-to-cell signaling in developing synapses of central neurons.
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Affiliation(s)
- Emily G Severance
- Department of Pharmacology and Therapeutics, University of South Florida College of Medicine, MDC 9, 12901 Bruce B. Downs Blvd. Tampa, FL 33612-4799, USA
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