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Perez-Miller S, Gomez K, Khanna R. Peptide and Peptidomimetic Inhibitors Targeting the Interaction of Collapsin Response Mediator Protein 2 with the N-Type Calcium Channel for Pain Relief. ACS Pharmacol Transl Sci 2024; 7:1916-1936. [PMID: 39022365 PMCID: PMC11249630 DOI: 10.1021/acsptsci.4c00181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/13/2024] [Accepted: 05/23/2024] [Indexed: 07/20/2024]
Abstract
Ion channels serve pleiotropic functions. Often found in complexes, their activities and functions are sculpted by auxiliary proteins. We discovered that collapsin response mediator protein 2 (CRMP2) is a binding partner and regulator of the N-type voltage-gated calcium channel (CaV2.2), a genetically validated contributor to chronic pain. Herein, we trace the discovery of a new peptidomimetic modulator of this interaction, starting from the identification and development of CBD3, a CRMP2-derived CaV binding domain peptide. CBD3 uncouples CRMP2-CaV2.2 binding to decrease CaV2.2 surface localization and calcium currents. These changes occur at presynaptic sites of nociceptive neurons and indeed, CBD3 ameliorates chronic pain in preclinical models. In pursuit of a CBD3 peptidomimetic, we exploited a unique approach to identify a dipeptide with low conformational flexibility and high solvent accessibility that anchors binding to CaV2.2. From a pharmacophore screen, we obtained CBD3063, a small-molecule that recapitulated CBD3's activity, reversing nociceptive behaviors in rodents of both sexes without sensory, affective, or cognitive effects. By disrupting the CRMP2-CaV2.2 interaction, CBD3063 exerts these effects indirectly through modulating CaV2.2 trafficking, supporting CRMP2 as an auxiliary subunit of CaV2.2. The parent peptide CBD3 was also found by us and others to have neuroprotective properties at postsynaptic sites, through N-methyl-d-aspartate receptor and plasmalemmal Na+/Ca2+ exchanger 3, potentially acting as an auxiliary subunit for these pathways as well. Our new compound is poised to address several open questions regarding CRMP2's role in regulating the CaV2.2 pathways to treat pain with the potential added benefit of neuroprotection.
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Affiliation(s)
- Samantha Perez-Miller
- Department
of Pharmacology & Therapeutics, College of Medicine, University of Florida, 1200 Newell Drive, ARB R5-234, Gainesville, Florida 32610-0267, United States
| | - Kimberly Gomez
- Department
of Pharmacology & Therapeutics, College of Medicine, University of Florida, 1200 Newell Drive, ARB R5-234, Gainesville, Florida 32610-0267, United States
| | - Rajesh Khanna
- Department
of Pharmacology & Therapeutics, College of Medicine, University of Florida, 1200 Newell Drive, ARB R5-234, Gainesville, Florida 32610-0267, United States
- Pain
and Addiction Therapeutics (PATH) Collaboratory, College of Medicine, University of Florida, Gainesville, Florida 32610, United States
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2
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Coutens B, Ingram SL. Key differences in regulation of opioid receptors localized to presynaptic terminals compared to somas: Relevance for novel therapeutics. Neuropharmacology 2023; 226:109408. [PMID: 36584882 PMCID: PMC9898207 DOI: 10.1016/j.neuropharm.2022.109408] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 12/05/2022] [Accepted: 12/27/2022] [Indexed: 12/29/2022]
Abstract
Opioid receptors are G protein-coupled receptors (GPCRs) that regulate activity within peripheral, subcortical and cortical circuits involved in pain, reward, and aversion processing. Opioid receptors are expressed in both presynaptic terminals where they inhibit neurotransmitter release and postsynaptic locations where they act to hyperpolarize neurons and reduce activity. Agonist activation of postsynaptic receptors at the plasma membrane signal via ion channels or cytoplasmic second messengers. Agonist binding initiates regulatory processes that include phosphorylation by G protein receptor kinases (GRKs) and recruitment of beta-arrestins that desensitize and internalize the receptors. Opioid receptors also couple to effectors from endosomes activating intracellular enzymes and kinases. In contrast to postsynaptic opioid receptors, receptors localized to presynaptic terminals are resistant to desensitization such that there is no loss of signaling in the continuous presence of opioids over the same time scale. Thus, the balance of opioid signaling in circuits expressing pre- and postsynaptic opioid receptors is shifted toward inhibition of presynaptic neurotransmitter release during continuous opioid exposure. The functional implication of this shift is not often acknowledged in behavioral studies. This review covers what is currently understood about regulation of opioid/nociceptin receptors, with an emphasis on opioid receptor signaling in pain and reward circuits. Importantly, the review covers regulation of presynaptic receptors and the critical gaps in understanding this area, as well as the opportunities to further understand opioid signaling in brain circuits. This article is part of the Special Issue on "Opioid-induced changes in addiction and pain circuits".
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Affiliation(s)
- Basile Coutens
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Susan L Ingram
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA.
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3
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Hartung JE, Moy JK, Loeza-Alcocer E, Nagarajan V, Jostock R, Christoph T, Schroeder W, Gold MS. Voltage-gated calcium currents in human dorsal root ganglion neurons. Pain 2022; 163:e774-e785. [PMID: 34510139 PMCID: PMC8882208 DOI: 10.1097/j.pain.0000000000002465] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 08/10/2021] [Indexed: 11/25/2022]
Abstract
ABSTRACT Voltage-gated calcium channels in sensory neurons underlie processes ranging from neurotransmitter release to gene expression and remain a therapeutic target for the treatment of pain. Yet virtually all we know about voltage-gated calcium channels has been obtained through the study of rodent sensory neurons and heterologously expressed channels. To address this, high voltage-activated (HVA) Ca2+ currents in dissociated human and rat dorsal root ganglion neurons were characterized with whole-cell patch clamp techniques. The HVA currents from both species shared basic biophysical and pharmacological properties. However, HVA currents in human neurons differed from those in the rat in at least 3 potentially important ways: (1) Ca2+ current density was significantly smaller, (2) the proportion of nifedipine-sensitive currents was far greater, and (3) a subpopulation of human neurons displayed relatively large constitutive current inhibition. These results highlight the need to for the study of native proteins in their native environment before initiating costly clinical trials.
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Affiliation(s)
- Jane E Hartung
- University of Pittsburgh School of Medicine, Department of Neurobiology, PA, USA
| | - Jamie K Moy
- University of Pittsburgh School of Medicine, Department of Neurobiology, PA, USA
| | | | - Vidhya Nagarajan
- University of Pittsburgh School of Medicine, Department of Neurobiology, PA, USA
| | | | | | | | - Michael S Gold
- University of Pittsburgh School of Medicine, Department of Neurobiology, PA, USA
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4
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Sun L, Tong CK, Morgenstern TJ, Zhou H, Yang G, Colecraft HM. Targeted ubiquitination of sensory neuron calcium channels reduces the development of neuropathic pain. Proc Natl Acad Sci U S A 2022; 119:e2118129119. [PMID: 35561213 PMCID: PMC9171802 DOI: 10.1073/pnas.2118129119] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 04/01/2022] [Indexed: 11/18/2022] Open
Abstract
Neuropathic pain caused by lesions to somatosensory neurons due to injury or disease is a widespread public health problem that is inadequately managed by small-molecule therapeutics due to incomplete pain relief and devastating side effects. Genetically encoded molecules capable of interrupting nociception have the potential to confer long-lasting analgesia with minimal off-target effects. Here, we utilize a targeted ubiquitination approach to achieve a unique posttranslational functional knockdown of high-voltage-activated calcium channels (HVACCs) that are obligatory for neurotransmission in dorsal root ganglion (DRG) neurons. CaV-aβlator comprises a nanobody targeted to CaV channel cytosolic auxiliary β subunits fused to the catalytic HECT domain of the Nedd4-2 E3 ubiquitin ligase. Subcutaneous injection of adeno-associated virus serotype 9 encoding CaV-aβlator in the hind paw of mice resulted in the expression of the protein in a subset of DRG neurons that displayed a concomitant ablation of CaV currents and also led to an increase in the frequency of spontaneous inhibitory postsynaptic currents in the dorsal horn of the spinal cord. Mice subjected to spare nerve injury displayed a characteristic long-lasting mechanical, thermal, and cold hyperalgesia underlain by a dramatic increase in coordinated phasic firing of DRG neurons as reported by in vivo Ca2+ spike recordings. CaV-aβlator significantly dampened the integrated Ca2+ spike activity and the hyperalgesia in response to nerve injury. The results advance the principle of targeting HVACCs as a gene therapy for neuropathic pain and demonstrate the therapeutic potential of posttranslational functional knockdown of ion channels achieved by exploiting the ubiquitin-proteasome system.
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Affiliation(s)
- Linlin Sun
- Department of Anesthesiology, Columbia University Medical Center, New York, NY 10032
| | - Chi-Kun Tong
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, NY 10032
| | - Travis J. Morgenstern
- Department of Molecular Pharmacology and Therapeutics, Columbia University Medical Center, New York, NY 10032
| | - Hang Zhou
- Department of Anesthesiology, Columbia University Medical Center, New York, NY 10032
| | - Guang Yang
- Department of Anesthesiology, Columbia University Medical Center, New York, NY 10032
| | - Henry M. Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, NY 10032
- Department of Molecular Pharmacology and Therapeutics, Columbia University Medical Center, New York, NY 10032
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5
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Colecraft HM, Trimmer JS. Controlling ion channel function with renewable recombinant antibodies. J Physiol 2022; 600:2023-2036. [PMID: 35238051 PMCID: PMC9058206 DOI: 10.1113/jp282403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 02/11/2022] [Indexed: 11/08/2022] Open
Abstract
Selective ion channel modulators play a critical role in physiology in defining the contribution of specific ion channels to physiological function and as proof of concept for novel therapeutic strategies. Antibodies are valuable research tools that have broad uses including defining the expression and localization of ion channels in native tissue, and capturing ion channel proteins for subsequent analyses. In this review, we detail how renewable and recombinant antibodies can be used to control ion channel function. We describe the different forms of renewable and recombinant antibodies that have been used and the mechanisms by which they modulate ion channel function. We highlight the use of recombinant antibodies that are expressed intracellularly (intrabodies) as genetically-encoded tools to control ion channel function. We also offer perspectives of avenues of future research that may be opened by the application of emerging technologies for engineering recombinant antibodies for enhanced utility in ion channel research. Overall, this review provides insights that may help stimulate and guide interested researchers to develop and incorporate renewable and recombinant antibodies as valuable tools to control ion channel function. Abstract figure legend Two different approaches for controlling ion channel function using renewable recombinant antibodies. On the left, an externally applied intact IgG antibody (purple) binds to an extracellular domain of an ion channel (light blue) to control ion channel function. On the right, a genetically-encoded intrabody, in this example a camelid nanobody (green) fused to an effector molecule (red) binds to an intracellular auxiliary subunit of an ion channel (dark blue) to control ion channel function. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Henry M Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, 10032, USA
| | - James S Trimmer
- Department of Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA, 95616, USA
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Bunda A, Andrade A. BaseScope™ Approach to Visualize Alternative Splice Variants in Tissue. Methods Mol Biol 2022; 2537:185-196. [PMID: 35895265 DOI: 10.1007/978-1-0716-2521-7_11] [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: 10/16/2022]
Abstract
Defining the cell-specific alternative splicing landscape in complex tissues is an important goal to gain functional insights. Deep-sequencing techniques coupled to genetic strategies for cell identification has provided important cues on cell-specific exon usage in complex tissues like the nervous system. BaseScope™ has emerged as a powerful and highly sensitive alternative to in situ hybridization to determine exon composition in tissue with spatial and morphological context. In this protocol, we will review how BaseScope was utilized to detect the e37a-Cacna1b splice variant of the presynaptic calcium channel CaV2.2 or N-type. This splice variant arises from a pair of mutually exclusive exons (e37a and e37b). E37a-Cacna1b is heavily underrepresented relative to e37b-Cacna1b and both exons share 60% of their sequence. By using BaseScope™, we were able to discover that e37a-Cacna1b is expressed in excitatory pyramidal neurons of hippocampus and cortex, as well as motor neurons of the ventral horn of the spinal cord.
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Affiliation(s)
- Alexandra Bunda
- Department of Biological Sciences, College of Life Sciences and Agriculture, University of New Hampshire, Durham, NH, USA
| | - Arturo Andrade
- Department of Biological Sciences, College of Life Sciences and Agriculture, University of New Hampshire, Durham, NH, USA.
- Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI, USA.
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7
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Patel AA, Sakurai A, Himmel NJ, Cox DN. Modality specific roles for metabotropic GABAergic signaling and calcium induced calcium release mechanisms in regulating cold nociception. Front Mol Neurosci 2022; 15:942548. [PMID: 36157080 PMCID: PMC9502035 DOI: 10.3389/fnmol.2022.942548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 08/23/2022] [Indexed: 11/13/2022] Open
Abstract
Calcium (Ca2+) plays a pivotal role in modulating neuronal-mediated responses to modality-specific sensory stimuli. Recent studies in Drosophila reveal class III (CIII) multidendritic (md) sensory neurons function as multimodal sensors regulating distinct behavioral responses to innocuous mechanical and nociceptive thermal stimuli. Functional analyses revealed CIII-mediated multimodal behavioral output is dependent upon activation levels with stimulus-evoked Ca2+ displaying relatively low vs. high intracellular levels in response to gentle touch vs. noxious cold, respectively. However, the mechanistic bases underlying modality-specific differential Ca2+ responses in CIII neurons remain incompletely understood. We hypothesized that noxious cold-evoked high intracellular Ca2+ responses in CIII neurons may rely upon Ca2+ induced Ca2+ release (CICR) mechanisms involving transient receptor potential (TRP) channels and/or metabotropic G protein coupled receptor (GPCR) activation to promote cold nociceptive behaviors. Mutant and/or CIII-specific knockdown of GPCR and CICR signaling molecules [GABA B -R2, Gαq, phospholipase C, ryanodine receptor (RyR) and Inositol trisphosphate receptor (IP3R)] led to impaired cold-evoked nociceptive behavior. GPCR mediated signaling, through GABA B -R2 and IP3R, is not required in CIII neurons for innocuous touch evoked behaviors. However, CICR via RyR is required for innocuous touch-evoked behaviors. Disruptions in GABA B -R2, IP3R, and RyR in CIII neurons leads to significantly lower levels of cold-evoked Ca2+ responses indicating GPCR and CICR signaling mechanisms function in regulating Ca2+ release. CIII neurons exhibit bipartite cold-evoked firing patterns, where CIII neurons burst during rapid temperature change and tonically fire during steady state cold temperatures. GABA B -R2 knockdown in CIII neurons resulted in disorganized firing patterns during cold exposure. We further demonstrate that application of GABA or the GABA B specific agonist baclofen potentiates cold-evoked CIII neuron activity. Upon ryanodine application, CIII neurons exhibit increased bursting activity and with CIII-specific RyR knockdown, there is an increase in cold-evoked tonic firing and decrease in bursting. Lastly, our previous studies implicated the TRPP channel Pkd2 in cold nociception, and here, we show that Pkd2 and IP3R genetically interact to specifically regulate cold-evoked behavior, but not innocuous mechanosensation. Collectively, these analyses support novel, modality-specific roles for metabotropic GABAergic signaling and CICR mechanisms in regulating intracellular Ca2+ levels and cold-evoked behavioral output from multimodal CIII neurons.
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Affiliation(s)
- Atit A Patel
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Akira Sakurai
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Nathaniel J Himmel
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Daniel N Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
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8
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Heck J, Palmeira Do Amaral AC, Weißbach S, El Khallouqi A, Bikbaev A, Heine M. More than a pore: How voltage-gated calcium channels act on different levels of neuronal communication regulation. Channels (Austin) 2021; 15:322-338. [PMID: 34107849 PMCID: PMC8205089 DOI: 10.1080/19336950.2021.1900024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/04/2021] [Accepted: 03/04/2021] [Indexed: 02/06/2023] Open
Abstract
Voltage-gated calcium channels (VGCCs) represent key regulators of the calcium influx through the plasma membrane of excitable cells, like neurons. Activated by the depolarization of the membrane, the opening of VGCCs induces very transient and local changes in the intracellular calcium concentration, known as calcium nanodomains, that in turn trigger calcium-dependent signaling cascades and the release of chemical neurotransmitters. Based on their central importance as concierges of excitation-secretion coupling and therefore neuronal communication, VGCCs have been studied in multiple aspects of neuronal function and malfunction. However, studies on molecular interaction partners and recent progress in omics technologies have extended the actual concept of these molecules. With this review, we want to illustrate some new perspectives of VGCCs reaching beyond their function as calcium-permeable pores in the plasma membrane. Therefore, we will discuss the relevance of VGCCs as voltage sensors in functional complexes with ryanodine receptors, channel-independent actions of auxiliary VGCC subunits, and provide an insight into how VGCCs even directly participate in gene regulation. Furthermore, we will illustrate how structural changes in the intracellular C-terminus of VGCCs generated by alternative splicing events might not only affect the biophysical channel characteristics but rather determine their molecular environment and downstream signaling pathways.
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Affiliation(s)
- Jennifer Heck
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Ana Carolina Palmeira Do Amaral
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Stephan Weißbach
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
- Computational Genomics and Bioinformatics, Johannes Gutenberg-University Mainz, University Medical Center Mainz, Institute for Human Genetics, Mainz, Germany
| | - Abderazzaq El Khallouqi
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Arthur Bikbaev
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
| | - Martin Heine
- Functional Neurobiology, Johannes Gutenberg-University Mainz, Institute for Developmental Biology and Neurobiology, Mainz, Germany
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Lipscombe D, Lopez-Soto EJ. Epigenetic control of ion channel expression and cell-specific splicing in nociceptors: Chronic pain mechanisms and potential therapeutic targets. Channels (Austin) 2021; 15:156-164. [PMID: 33323031 PMCID: PMC7808434 DOI: 10.1080/19336950.2020.1860383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 12/03/2020] [Indexed: 12/17/2022] Open
Abstract
Ion channels underlie all forms for electrical signaling including the transmission of information about harmful events. Voltage-gated calcium ion channels have dual function, they support electrical signaling as well as intracellular calcium signaling through excitation-dependent calcium entry across the plasma membrane. Mechanisms that regulate ion channel forms and actions are essential for myriad cell functions and these are targeted by drugs and therapeutics. When disrupted, the cellular mechanisms that control ion channel activity can contribute to disease pathophysiology. For example, alternative pre-mRNA splicing is a major step in defining the precise composition of the transcriptome across different cell types from early cellular differentiation to programmed apoptosis. An estimated 30% of disease-causing mutations are associated with altered alternative splicing, and mis-splicing is a feature of numerous highly prevalent diseases including neurodegenerative, cancer, and chronic pain. Here we discuss the important role of epigenetic regulation of gene expression and cell-specific alternative splicing of calcium ion channels in nociceptors, with emphasis on how these processes are disrupted in chronic pain, the potential therapeutic benefit of correcting or compensating for aberrant ion channel splicing in chronic pain.
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Affiliation(s)
- Diane Lipscombe
- The Robert J and Nancy D Carney Institute for Brain Science & Department of Neuroscience, Brown University, Providence, RI, USA
| | - E. Javier Lopez-Soto
- The Robert J and Nancy D Carney Institute for Brain Science & Department of Neuroscience, Brown University, Providence, RI, USA
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10
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Weiss N, Zamponi GW. Opioid Receptor Regulation of Neuronal Voltage-Gated Calcium Channels. Cell Mol Neurobiol 2021; 41:839-847. [PMID: 32514826 DOI: 10.1007/s10571-020-00894-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 05/29/2020] [Indexed: 12/28/2022]
Abstract
Neuronal voltage-gated calcium channels play a pivotal role in the conversion of electrical signals into calcium entry into nerve endings that is required for the release of neurotransmitters. They are under the control of a number of cellular signaling pathways that serve to fine tune synaptic activities, including G-protein coupled receptors (GPCRs) and the opioid system. Besides modulating channel activity via activation of second messengers, GPCRs also physically associate with calcium channels to regulate their function and expression at the plasma membrane. In this mini review, we discuss the mechanisms by which calcium channels are regulated by classical opioid and nociceptin receptors. We highlight the importance of this regulation in the control of neuronal functions and their implication in the development of disease conditions. Finally, we present recent literature concerning the use of novel μ-opioid receptor/nociceptin receptor modulators and discuss their use as potential drug candidates for the treatment of pain.
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Affiliation(s)
- Norbert Weiss
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
- Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada.
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11
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Chen W, McRoberts JA, Ennes HS, Marvizon JC. cAMP signaling through protein kinase A and Epac2 induces substance P release in the rat spinal cord. Neuropharmacology 2021; 189:108533. [PMID: 33744339 DOI: 10.1016/j.neuropharm.2021.108533] [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: 08/12/2020] [Revised: 03/01/2021] [Accepted: 03/11/2021] [Indexed: 11/18/2022]
Abstract
Using neurokinin 1 receptor (NK1R) internalization to measure of substance P release in rat spinal cord slices, we found that it was induced by the adenylyl cyclase (AC) activator forskolin, by the protein kinase A (PKA) activators 6-Bnz-cAMP and 8-Br-cAMP, and by the activator of exchange protein activated by cAMP (Epac) 8-pCPT-2-O-Me-cAMP (CPTOMe-cAMP). Conversely, AC and PKA inhibitors decreased substance P release induced by electrical stimulation of the dorsal root. Therefore, the cAMP signaling pathway mediates substance P release in the dorsal horn. The effects of forskolin and 6-Bnz-cAMP were not additive with NMDA-induced substance P release and were decreased by the NMDA receptor blocker MK-801. In cultured dorsal horn neurons, forskolin increased NMDA-induced Ca2+ entry and the phosphorylation of the NR1 and NR2B subunits of the NMDA receptor. Therefore, cAMP-induced substance P release is mediated by the activating phosphorylation by PKA of NMDA receptors. Voltage-gated Ca2+ channels, but not by TRPV1 or TRPA1, also contributed to cAMP-induced substance P release. Activation of PKA was required for the effects of forskolin and the three cAMP analogs. Epac2 contributed to the effects of forskolin and CPTOMe-cAMP, signaling through a Raf - mitogen-activated protein kinase pathway to activate Ca2+ channels. Epac1 inhibitors induced NK1R internalization independently of substance P release. In rats with latent sensitization to pain, the effect of 6-Bnz-cAMP was unchanged, whereas the effect of forskolin was decreased due to the loss of the stimulatory effect of Epac2. Hence, substance P release induced by cAMP decreases during pain hypersensitivity.
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Affiliation(s)
- Wenling Chen
- Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA, 90095, USA; Veteran Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, 90073, USA
| | - James A McRoberts
- Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Helena S Ennes
- Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Juan Carlos Marvizon
- Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA, 90095, USA; Veteran Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, 90073, USA.
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12
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Yang WJ, Yan AZ, Xu YJ, Guo XY, Fu XG, Li D, Liao J, Zhang D, Lan FH. Further identification of a 140bp sequence from amid intron 9 of human FMR1 gene as a new exon. BMC Genet 2020; 21:63. [PMID: 32552710 PMCID: PMC7301526 DOI: 10.1186/s12863-020-00870-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 06/09/2020] [Indexed: 11/24/2022] Open
Abstract
Background The disease gene of fragile X syndrome, FMR1 gene, encodes fragile X mental retardation protein (FMRP). The alternative splicing (AS) of FMR1 can affect the structure and function of FMRP. However, the biological functions of alternatively spliced isoforms remain elusive. In a previous study, we identified a new 140bp exon from the intron 9 of human FMR1 gene. In this study, we further examined the biological functions of this new exon and its underlying signaling pathways. Results qRT-PCR results showed that this novel exon is commonly expressed in the peripheral blood of normal individuals. Comparative genomics showed that sequences paralogous to the 140 bp sequence only exist in the genomes of primates. To explore the biological functions of the new transcript, we constructed recombinant eukaryotic expression vectors and lentiviral overexpression vectors. Results showed that the spliced transcript encoded a truncated protein which was expressed mainly in the cell nucleus. Additionally, several genes, including the BEX1 gene involved in mGluR-LTP or mGluR-LTD signaling pathways were significantly influenced when the truncated FMRP was overexpressed. Conclusions our work identified a new exon from amid intron 9 of human FMR1 gene with wide expression in normal healthy individuals, which emphasizes the notion that the AS of FMR1 gene is complex and may in a large part account for the multiple functions of FMRP.
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Affiliation(s)
- Wen-Jing Yang
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Xiamen University School of Medicine, 156 Xi'erhuanbei Road, Fuzhou City, Fujian Province, 350025, People's Republic of China.,Present addresses: Department of Laboratory Medicine, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Ai-Zhen Yan
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Xiamen University School of Medicine, 156 Xi'erhuanbei Road, Fuzhou City, Fujian Province, 350025, People's Republic of China
| | - Yong-Jun Xu
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Xiamen University School of Medicine, 156 Xi'erhuanbei Road, Fuzhou City, Fujian Province, 350025, People's Republic of China
| | - Xiao-Yan Guo
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Xiamen University School of Medicine, 156 Xi'erhuanbei Road, Fuzhou City, Fujian Province, 350025, People's Republic of China.,Present addresses: Department of Laboratory Medicine, Fuzhou No. 2 Hospital Affiliated Xiamen University, Fuzhou, Fujian, 350007, People's Republic of China
| | - Xian-Guo Fu
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Xiamen University School of Medicine, 156 Xi'erhuanbei Road, Fuzhou City, Fujian Province, 350025, People's Republic of China.,Present addresses: Department of Laboratory Medicine, Ningde Municipal Hospital, Fujian Medical University, Ningde City, 352100, Fujian Province, China
| | - Dan Li
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Xiamen University School of Medicine, 156 Xi'erhuanbei Road, Fuzhou City, Fujian Province, 350025, People's Republic of China
| | - Juan Liao
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Xiamen University School of Medicine, 156 Xi'erhuanbei Road, Fuzhou City, Fujian Province, 350025, People's Republic of China.,Present addresses: Department of Laboratory Medicine, Fujian University of Traditional Chinese Medicine Affiliated People's Hospital, Fuzhou, 350001, Fujian, China
| | - Duo Zhang
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Xiamen University School of Medicine, 156 Xi'erhuanbei Road, Fuzhou City, Fujian Province, 350025, People's Republic of China
| | - Feng-Hua Lan
- Department of Clinical Genetics and Experimental Medicine, 900th Hospital of the Joint Logistics Force, Xiamen University School of Medicine, 156 Xi'erhuanbei Road, Fuzhou City, Fujian Province, 350025, People's Republic of China.
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13
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Selected Ionotropic Receptors and Voltage-Gated Ion Channels: More Functional Competence for Human Induced Pluripotent Stem Cell (iPSC)-Derived Nociceptors. Brain Sci 2020; 10:brainsci10060344. [PMID: 32503260 PMCID: PMC7348931 DOI: 10.3390/brainsci10060344] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 05/28/2020] [Accepted: 05/30/2020] [Indexed: 01/09/2023] Open
Abstract
Preclinical research using different rodent model systems has largely contributed to the scientific progress in the pain field, however, it suffers from interspecies differences, limited access to human models, and ethical concerns. Human induced pluripotent stem cells (iPSCs) offer major advantages over animal models, i.e., they retain the genome of the donor (patient), and thus allow donor-specific and cell-type specific research. Consequently, human iPSC-derived nociceptors (iDNs) offer intriguingly new possibilities for patient-specific, animal-free research. In the present study, we characterized iDNs based on the expression of well described nociceptive markers and ion channels, and we conducted a side-by-side comparison of iDNs with mouse sensory neurons. Specifically, immunofluorescence (IF) analyses with selected markers including early somatosensory transcription factors (BRN3A/ISL1/RUNX1), the low-affinity nerve growth factor receptor (p75), hyperpolarization-activated cyclic nucleotide-gated channels (HCN), as well as high voltage-gated calcium channels (VGCC) of the CaV2 type, calcium permeable TRPV1 channels, and ionotropic GABAA receptors, were used to address the characteristics of the iDN phenotype. We further combined IF analyses with microfluorimetric Ca2+ measurements to address the functionality of these ion channels in iDNs. Thus, we provide a detailed morphological and functional characterization of iDNs, thereby, underpinning their enormous potential as an animal-free alternative for human specific research in the pain field for unveiling pathophysiological mechanisms and for unbiased, disease-specific personalized drug development.
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Thalhammer A, Jaudon F, Cingolani LA. Emerging Roles of Activity-Dependent Alternative Splicing in Homeostatic Plasticity. Front Cell Neurosci 2020; 14:104. [PMID: 32477067 PMCID: PMC7235277 DOI: 10.3389/fncel.2020.00104] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 04/06/2020] [Indexed: 12/25/2022] Open
Abstract
Homeostatic plasticity refers to the ability of neuronal networks to stabilize their activity in the face of external perturbations. Most forms of homeostatic plasticity ultimately depend on changes in the expression or activity of ion channels and synaptic proteins, which may occur at the gene, transcript, or protein level. The most extensively investigated homeostatic mechanisms entail adaptations in protein function or localization following activity-dependent posttranslational modifications. Numerous studies have also highlighted how homeostatic plasticity can be achieved by adjusting local protein translation at synapses or transcription of specific genes in the nucleus. In comparison, little attention has been devoted to whether and how alternative splicing (AS) of pre-mRNAs underlies some forms of homeostatic plasticity. AS not only expands proteome diversity but also contributes to the spatiotemporal dynamics of mRNA transcripts. Prominent in the brain where it can be regulated by neuronal activity, it is a flexible process, tightly controlled by a multitude of factors. Given its extensive use and versatility in optimizing the function of ion channels and synaptic proteins, we argue that AS is ideally suited to achieve homeostatic control of neuronal output. We support this thesis by reviewing emerging evidence linking AS to various forms of homeostatic plasticity: homeostatic intrinsic plasticity, synaptic scaling, and presynaptic homeostatic plasticity. Further, we highlight the relevance of this connection for brain pathologies.
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Affiliation(s)
- Agnes Thalhammer
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Fanny Jaudon
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Lorenzo A Cingolani
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), Genoa, Italy.,Department of Life Sciences, University of Trieste, Trieste, Italy
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15
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Torz LJ, Osborne-Lawrence S, Rodriguez J, He Z, Cornejo MP, Mustafá ER, Jin C, Petersen N, Hedegaard MA, Nybo M, Damonte VM, Metzger NP, Mani BK, Williams KW, Raingo J, Perello M, Holst B, Zigman JM. Metabolic insights from a GHSR-A203E mutant mouse model. Mol Metab 2020; 39:101004. [PMID: 32339772 PMCID: PMC7242877 DOI: 10.1016/j.molmet.2020.101004] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 04/13/2020] [Accepted: 04/16/2020] [Indexed: 02/02/2023] Open
Abstract
Objective Binding of ghrelin to its receptor, growth hormone secretagogue receptor (GHSR), stimulates GH release, induces eating, and increases blood glucose. These processes may also be influenced by constitutive (ghrelin-independent) GHSR activity, as suggested by findings in short people with naturally occurring GHSR-A204E mutations and reduced food intake and blood glucose in rodents administered GHSR inverse agonists, both of which impair constitutive GHSR activity. In this study, we aimed to more fully determine the physiologic relevance of constitutive GHSR activity. Methods We generated mice with a GHSR mutation that replaces alanine at position 203 with glutamate (GHSR-A203E), which corresponds to the previously described human GHSR-A204E mutation, and used them to conduct ex vivo neuronal electrophysiology and in vivo metabolic assessments. We also measured signaling within COS-7 and HEK293T cells transfected with wild-type GHSR (GHSR-WT) or GHSR-A203E constructs. Results In COS-7 cells, GHSR-A203E resulted in lower baseline IP3 accumulation than GHSR-WT; ghrelin-induced IP3 accumulation was observed in both constructs. In HEK293T cells co-transfected with voltage-gated CaV2.2 calcium channel complex, GHSR-A203E had no effect on basal CaV2.2 current density while GHSR-WT did; both GHSR-A203E and GHSR-WT inhibited CaV2.2 current in the presence of ghrelin. In cultured hypothalamic neurons from GHSR-A203E and GHSR-deficient mice, native calcium currents were greater than those in neurons from wild-type mice; ghrelin inhibited calcium currents in cultured hypothalamic neurons from both GHSR-A203E and wild-type mice. In brain slices, resting membrane potentials of arcuate NPY neurons from GHSR-A203E mice were hyperpolarized compared to those from wild-type mice; the same percentage of arcuate NPY neurons from GHSR-A203E and wild-type mice depolarized upon ghrelin exposure. The GHSR-A203E mutation did not significantly affect body weight, body length, or femur length in the first ∼6 months of life, yet these parameters were lower in GHSR-A203E mice after 1 year of age. During a 7-d 60% caloric restriction regimen, GHSR-A203E mice lacked the usual marked rise in plasma GH and demonstrated an exaggerated drop in blood glucose. Administered ghrelin also exhibited reduced orexigenic and GH secretagogue efficacies in GHSR-A203E mice. Conclusions Our data suggest that the A203E mutation ablates constitutive GHSR activity and that constitutive GHSR activity contributes to the native depolarizing conductance of GHSR-expressing arcuate NPY neurons. Although the A203E mutation does not block ghrelin-evoked signaling as assessed using in vitro and ex vivo models, GHSR-A203E mice lack the usual acute food intake response to administered ghrelin in vivo. The GHSR-A203E mutation also blunts GH release, and in aged mice leads to reduced body length and femur length, which are consistent with the short stature of human carriers of the GHSR-A204E mutation. We generated mice with a GHSR mutation replacing Ala at position 203 with Glu. The A203E mutation ablates constitutive GHSR activity & hyperpolarizes NPY neurons. GHSR-A203E mice lack the usual orexigenic response to administered ghrelin. The GHSR-A203E mutation blunts GH release and causes reduced body length. This finding is consistent with short stature in human carriers of the GHSR-A204E mutation.
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Affiliation(s)
- Lola J Torz
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Sherri Osborne-Lawrence
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Juan Rodriguez
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Zhenyan He
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | | | - Emilio Román Mustafá
- Laboratory of Electrophysiology of the Multidisciplinary Institute of Cell Biology [Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA)], La Plata, Buenos Aires, Argentina
| | - Chunyu Jin
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Natalia Petersen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten A Hedegaard
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Maja Nybo
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Valentina Martínez Damonte
- Laboratory of Electrophysiology of the Multidisciplinary Institute of Cell Biology [Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA)], La Plata, Buenos Aires, Argentina
| | - Nathan P Metzger
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Bharath K Mani
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Kevin W Williams
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Jesica Raingo
- Laboratory of Electrophysiology of the Multidisciplinary Institute of Cell Biology [Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA)], La Plata, Buenos Aires, Argentina
| | - Mario Perello
- Laboratory of Neurophysiology, La Plata, Buenos Aires, Argentina
| | - Birgitte Holst
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark.
| | - Jeffrey M Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA.
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16
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López Soto EJ, Lipscombe D. Cell-specific exon methylation and CTCF binding in neurons regulate calcium ion channel splicing and function. eLife 2020; 9:54879. [PMID: 32213287 PMCID: PMC7124252 DOI: 10.7554/elife.54879] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 03/26/2020] [Indexed: 12/14/2022] Open
Abstract
Cell-specific alternative splicing modulates myriad cell functions and is disrupted in disease. The mechanisms governing alternative splicing are known for relatively few genes and typically focus on RNA splicing factors. In sensory neurons, cell-specific alternative splicing of the presynaptic CaV channel Cacna1b gene modulates opioid sensitivity. How this splicing is regulated is unknown. We find that cell and exon-specific DNA hypomethylation permits CTCF binding, the master regulator of mammalian chromatin structure, which, in turn, controls splicing in a DRG-derived cell line. In vivo, hypomethylation of an alternative exon specifically in nociceptors, likely permits CTCF binding and expression of CaV2.2 channel isoforms with increased opioid sensitivity in mice. Following nerve injury, exon methylation is increased, and splicing is disrupted. Our studies define the molecular mechanisms of cell-specific alternative splicing of a functionally validated exon in normal and disease states – and reveal a potential target for the treatment of chronic pain.
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Affiliation(s)
- Eduardo Javier López Soto
- The Robert J and Nancy D Carney Institute for Brain Science & Department of Neuroscience, Brown University, Providence, United States
| | - Diane Lipscombe
- The Robert J and Nancy D Carney Institute for Brain Science & Department of Neuroscience, Brown University, Providence, United States
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17
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Cordisco Gonzalez S, Mustafá ER, Rodriguez SS, Perello M, Raingo J. Dopamine Receptor Type 2 and Ghrelin Receptor Coexpression Alters Ca V2.2 Modulation by G Protein Signaling Cascades. ACS Chem Neurosci 2020; 11:3-13. [PMID: 31808667 DOI: 10.1021/acschemneuro.9b00426] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Voltage-gated calcium channels type 2.2 (CaV2.2) are activated by action potentials at presynaptic terminals, and their calcium current induces neurotransmitter release. In this context, regulating CaV2.2 is critical, and one of the most important mechanisms for doing so is through its G protein-coupled receptor (GPCR) activity. Two such GPCRs are the ghrelin (GHSR) and the dopamine type 2 (D2R) receptors. We previously demonstrated that constitutive GHSR activity reduces CaV2.2 forward trafficking and that ghrelin-induced GHSR activity inhibits CaV2.2 currents. On the other hand, dopamine-induced D2R activity also inhibits CaV2.2 currents. It has been recently shown that D2R and GHSR form heteromers in hypothalamic neurons. This interaction profoundly changes the signaling cascades activated by dopamine and is necessary for dopamine-dependent anorexia. Here we explored how D2R-GHSR coexpression in HEK293T cells modulates the effect that each GPCR has on CaV2.2. We found that D2R-GHSR coexpression reduces the inhibition of CaV2.2 currents by agonist-induced D2R activation and added a new source of basal CaV2.2 current inhibition to the one produced by GHSR solely expression. We investigated the signaling cascades implicated and found that constitutive GHSR activity, Gq protein, and Gβγ subunit play a critical role in these altered effects. Moreover, we found that the effect of D2R agonist on native calcium currents in hypothalamic neurons is reduced when both D2R and GHSR are overexpressed. In summary, our results allow us to propose a novel mechanism for controlling CaV2.2 currents involving the coexpression of two physiologically relevant GPCRs.
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18
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Gandini MA, Souza IA, Raval D, Xu J, Pan YX, Zamponi GW. Differential regulation of Cav2.2 channel exon 37 variants by alternatively spliced μ-opioid receptors. Mol Brain 2019; 12:98. [PMID: 31775826 PMCID: PMC6880636 DOI: 10.1186/s13041-019-0524-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 11/14/2019] [Indexed: 12/15/2022] Open
Abstract
We have examined the regulation of mutually exclusive Cav2.2 exon 37a and b variants by the mouse μ-opioid receptor (mMOR) C-terminal splice variants 1, 1C and 1O in tsA-201 cells. Electrophysiological analyses revealed that both channel isoforms exhibit DAMGO-induced voltage-dependent (Gβγ-mediated) inhibition and its recovery by voltage pre-pulses, as well as a voltage-independent component. However, the two channel isoforms differ in their relative extent of voltage-dependent and independent inhibition, with Cav2.2-37b showing significantly more voltage-dependent inhibition upon activation of the three mMOR receptors studied. In addition, coexpression of either mMOR1 or mMOR1C results in an agonist-independent reduction in the peak current density of Cav2.2-37a channels, whereas the peak current density of Cav2.2-37b does not appear to be affected. Interestingly, this decrease is not due to an effect on channel expression at the plasma membrane, as demonstrated by biotinylation experiments. We further examined the mechanism underlying the agonist-independent modulation of Cav2.2-37a by mMOR1C. Incubation of cells with pertussis toxin did not affect the mMOR1C mediated inhibition of Cav2.2-37a currents, indicating a lack of involvement of Gi/o signaling. However, when a Src tyrosine kinase inhibitor was applied, the effect of mMOR1C was lost. Moreover, when we recorded currents using a Cav2.2-37a mutant in which tyrosine 1747 was replaced with phenylalanine (Y1747F), the agonist independent effects of mMOR1C were abolished. Altogether our findings show that Cav2.2-37a and Cav2.2-37b isoforms are subject to differential regulation by C-terminal splice variants of mMORs, and that constitutive mMOR1C activity and downstream tyrosine kinase activity exert a selective inhibition of the Cav2.2-37a splice variant, an N-type channel isoform that is highly enriched in nociceptors. Our study provides new insights into the roles of the MOR full-length C-terminal variants in modulating Cav2.2 channel isoform activities.
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Affiliation(s)
- Maria A Gandini
- Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Ivana A Souza
- Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Dvij Raval
- Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Jin Xu
- Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Ying-Xian Pan
- Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
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Bunda A, LaCarubba B, Bertolino M, Akiki M, Bath K, Lopez-Soto J, Lipscombe D, Andrade A. Cacna1b alternative splicing impacts excitatory neurotransmission and is linked to behavioral responses to aversive stimuli. Mol Brain 2019; 12:81. [PMID: 31630675 PMCID: PMC6802325 DOI: 10.1186/s13041-019-0500-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 09/11/2019] [Indexed: 12/26/2022] Open
Abstract
Presynaptic CaV2.2 channels control calcium entry that triggers neurotransmitter release at both central and peripheral synapses. The Cacna1b gene encodes the α1-pore forming subunit of CaV2.2 channels. Distinct subsets of splice variants of CaV2.2 derived from cell-specific alternative splicing of the Cacna1b pre-mRNA are expressed in specific subpopulations of neurons. Four cell-specific sites of alternative splicing in Cacna1b that alter CaV2.2 channel function have been described in detail: three cassette exons (e18a, e24a, and e31a) and a pair of mutually exclusive exons (e37a/e37b). Cacna1b mRNAs containing e37a are highly enriched in a subpopulation of nociceptors where they influence nociception and morphine analgesia. E37a-Cacna1b mRNAs are also expressed in brain, but their cell-specific expression in this part of the nervous system, their functional consequences in central synapses and their role on complex behavior have not been studied. In this report, we show that e37a-Cacna1b mRNAs are expressed in excitatory projection neurons where CaV2.2 channels are known to influence transmitter release at excitatory inputs from entorhinal cortex (EC) to dentate gyrus (DG). By comparing behaviors of WT mice to those that only express e37b-CaV2.2 channels, we found evidence that e37a-CaV2.2 enhances behavioral responses to aversive stimuli. Our results suggest that alternative splicing of Cacna1b e37a influences excitatory transmitter release and couples to complex behaviors.
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Affiliation(s)
- Alexandra Bunda
- Department of Biological Sciences, College of Life Sciences and Agriculture, University of New Hampshire, 46 College Road, Durham, NH 03824 USA
| | - Brianna LaCarubba
- Department of Biological Sciences, College of Life Sciences and Agriculture, University of New Hampshire, 46 College Road, Durham, NH 03824 USA
| | - Melanie Bertolino
- Department of Biological Sciences, College of Life Sciences and Agriculture, University of New Hampshire, 46 College Road, Durham, NH 03824 USA
| | - Marie Akiki
- Department of Biological Sciences, College of Life Sciences and Agriculture, University of New Hampshire, 46 College Road, Durham, NH 03824 USA
| | - Kevin Bath
- Department of Cognitive, Linguistic and Psychological Sciences, Brown University, 190 Thayer Street, Providence, RI 02912 USA
| | - Javier Lopez-Soto
- Robert J and Nancy D Carney Institute for Brain Science & Department of Neuroscience, Brown University, 185 Meeting Street, Providence, RI 02912 USA
| | - Diane Lipscombe
- Robert J and Nancy D Carney Institute for Brain Science & Department of Neuroscience, Brown University, 185 Meeting Street, Providence, RI 02912 USA
| | - Arturo Andrade
- Department of Biological Sciences, College of Life Sciences and Agriculture, University of New Hampshire, 46 College Road, Durham, NH 03824 USA
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20
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Lopez Soto EJ, Gandal MJ, Gonatopoulos-Pournatzis T, Heller EA, Luo D, Zheng S. Mechanisms of Neuronal Alternative Splicing and Strategies for Therapeutic Interventions. J Neurosci 2019; 39:8193-8199. [PMID: 31619487 PMCID: PMC6794923 DOI: 10.1523/jneurosci.1149-19.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 08/09/2019] [Accepted: 08/10/2019] [Indexed: 01/15/2023] Open
Abstract
Many cellular and physiological processes are coordinated by regulatory networks that produce a remarkable complexity of transcript isoforms. In the mammalian nervous system, alternative pre-mRNA splicing generates functionally distinct isoforms that play key roles in normal physiology, supporting development, plasticity, complex behaviors, and cognition. Neuronal splicing programs controlled by RNA-binding proteins, are influenced by chromatin modifications and can exhibit neuronal subtype specificity. As highlighted in recent publications, aberrant alternative splicing is a major contributor to disease phenotypes. Therefore, understanding the underlying mechanisms of alternative splicing regulation and identifying functional splicing isoforms with critical phenotypic roles are expected to provide a comprehensive resource for therapeutic development, as illuminated by recent successful interventions of spinal muscular atrophy. Here, we discuss the latest progress in the study of the emerging complexity of alternative splicing mechanisms in neurons, and how these findings inform new therapies to correct and control splicing defects.
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Affiliation(s)
| | - Michael J Gandal
- Department of Psychiatry, Semel Institute, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095
| | | | - Elizabeth A Heller
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania 19104-5158
| | - Diou Luo
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, and
| | - Sika Zheng
- Division of Biomedical Sciences, University of California at Riverside, Riverside, California 92521
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21
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Joksimovic SL, Donald RR, Park JY, Todorovic SM. Inhibition of multiple voltage-gated calcium channels may contribute to spinally mediated analgesia by epipregnanolone in a rat model of surgical paw incision. Channels (Austin) 2019; 13:48-61. [PMID: 30672394 PMCID: PMC6380214 DOI: 10.1080/19336950.2018.1564420] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Voltage-activated calcium channels play an important role in excitability of sensory nociceptive neurons in acute and chronic pain models. We have previously shown that low-voltage-activated calcium channels, or T-type channels (T-channels), increase excitability of sensory neurons after surgical incision in rats. We have also found that endogenous 5β-reduced neuroactive steroid epipregnanolone [(3β,5β)-3-hydroxypregnan-20-one] blocked isolated T-currents in dorsal root ganglion (DRG) cells in vitro, and reduced nociceptive behavior in vivo, after local intraplantar application into the foot pads of heathy rats and mice. Here, we investigated if epipregnanolone exerts an antinociceptive effect after intrathecal (i.t.) application in healthy rats, as well as an antihyperalgesic effect in a postsurgical pain model. We also studied if this endogenous neurosteroid blocks currents originating from high voltage-activated (HVA) calcium channels in rat sensory neurons. In in vivo studies, we found that epipregnanolone alleviated thermal and mechanical nociception in healthy rats after i.t. administration without affecting their sensory-motor abilities. Furthermore, epipregnanolone effectively reduced mechanical hyperalgesia after i.t application in rats after surgery. In subsequent in vitro studies, we found that epipregnanolone blocked isolated HVA currents in nociceptive sensory neurons with an IC50 of 3.3 μM in a G-protein-dependent fashion. We conclude that neurosteroids that have combined inhibitory effects on T-type and HVA calcium currents may be suitable for development of novel pain therapies during the perioperative period.
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Affiliation(s)
- Sonja Lj Joksimovic
- a Department of Anesthesiology , University of Colorado Denver , Aurora , CO , USA
| | - Rebecca R Donald
- b Department of Anesthesiology , Duke University Medical School , Durham , NC , USA
| | - Ji-Yong Park
- c Department of Anesthesiology and Pain Medicine, College of Medicine , Korea University , Seoul , Republic of Korea
| | - Slobodan M Todorovic
- a Department of Anesthesiology , University of Colorado Denver , Aurora , CO , USA.,d Neuroscience Graduate Program , University of Colorado Denver , Aurora , CO , USA
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Mustafá ER, Cordisco Gonzalez S, Raingo J. Ghrelin Selectively Inhibits CaV3.3 Subtype of Low-Voltage-Gated Calcium Channels. Mol Neurobiol 2019; 57:722-735. [DOI: 10.1007/s12035-019-01738-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 08/16/2019] [Indexed: 01/01/2023]
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23
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Bunda A, LaCarubba B, Akiki M, Andrade A. Tissue- and cell-specific expression of a splice variant in the II-III cytoplasmic loop of Cacna1b. FEBS Open Bio 2019; 9:1603-1616. [PMID: 31314171 PMCID: PMC6722902 DOI: 10.1002/2211-5463.12701] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 06/19/2019] [Accepted: 07/15/2019] [Indexed: 11/25/2022] Open
Abstract
Presynaptic CaV2.2 (N‐type) channels are fundamental for transmitter release across the nervous system. The gene encoding CaV2.2 channels, Cacna1b, contains alternatively spliced exons that result in functionally distinct splice variants (e18a, e24a, e31a, and 37a/37b). Alternative splicing of the cassette exon 18a generates two mRNA transcripts (+e18a‐Cacna1b and ∆e18a‐Cacna1b). In this study, using novel mouse genetic models and in situ hybridization (BaseScope™), we confirmed that +e18a‐Cacna1b splice variants are expressed in monoaminergic regions of the midbrain. We expanded these studies and identified +e18a‐Cacna1b mRNA in deep cerebellar cells and spinal cord motor neurons. Furthermore, we determined that +e18a‐Cacna1b is enriched in cholecystokinin‐expressing interneurons. Our results provide key information to understand cell‐specific functions of CaV2.2 channels.
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Affiliation(s)
- Alexandra Bunda
- Department of Biological SciencesUniversity of New HampshireDurhamNHUSA
| | - Brianna LaCarubba
- Department of Biological SciencesUniversity of New HampshireDurhamNHUSA
| | - Marie Akiki
- Department of Biological SciencesUniversity of New HampshireDurhamNHUSA
| | - Arturo Andrade
- Department of Biological SciencesUniversity of New HampshireDurhamNHUSA
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Nanou E, Catterall WA. Calcium Channels, Synaptic Plasticity, and Neuropsychiatric Disease. Neuron 2019; 98:466-481. [PMID: 29723500 DOI: 10.1016/j.neuron.2018.03.017] [Citation(s) in RCA: 265] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 03/06/2018] [Accepted: 03/09/2018] [Indexed: 12/14/2022]
Abstract
Voltage-gated calcium channels couple depolarization of the cell-surface membrane to entry of calcium, which triggers secretion, contraction, neurotransmission, gene expression, and other physiological responses. They are encoded by ten genes, which generate three voltage-gated calcium channel subfamilies: CaV1; CaV2; and CaV3. At synapses, CaV2 channels form large signaling complexes in the presynaptic nerve terminal, which are responsible for the calcium entry that triggers neurotransmitter release and short-term presynaptic plasticity. CaV1 channels form signaling complexes in postsynaptic dendrites and dendritic spines, where their calcium entry induces long-term potentiation. These calcium channels are the targets of mutations and polymorphisms that alter their function and/or regulation and cause neuropsychiatric diseases, including migraine headache, cerebellar ataxia, autism, schizophrenia, bipolar disorder, and depression. This article reviews the molecular properties of calcium channels, considers their multiple roles in synaptic plasticity, and discusses their potential involvement in this wide range of neuropsychiatric diseases.
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Affiliation(s)
- Evanthia Nanou
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280, USA
| | - William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280, USA.
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Abstract
Whilst the nociceptin/orphanin FQ (N/OFQ) receptor (NOP) has similar intracellular coupling mechanisms to opioid receptors, it has distinct modulatory effects on physiological functions such as pain. These actions range from agonistic to antagonistic interactions with classical opioids within the spinal cord and brain, respectively. Understanding the electrophysiological actions of N/OFQ has been crucial in ascertaining the mechanisms by which these agonistic and antagonistic interactions occur. These similarities and differences between N/OFQ and opioids are due to the relative location of NOP versus opioid receptors on specific neuronal elements within these CNS regions. These mechanisms result in varied cellular actions including postsynaptic modulation of ion channels and presynaptic regulation of neurotransmitter release.
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26
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Williams B, Haeseleer F, Lee A. Splicing of an automodulatory domain in Ca v1.4 Ca 2+ channels confers distinct regulation by calmodulin. J Gen Physiol 2018; 150:1676-1687. [PMID: 30355583 PMCID: PMC6279360 DOI: 10.1085/jgp.201812140] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 10/03/2018] [Indexed: 12/17/2022] Open
Abstract
Cav1.4 Ca2+ channels provide maintained Ca2+ entry to support sustained neurotransmitter release, but a retinal splice variant exhibits calmodulin-dependent inactivation. Williams et al. show that the N lobe of calmodulin is involved in this process as well as Ca2+-dependent enhancement of channel activation. Ca2+ influx through Cav1.4 L-type Ca2+ channels supports the sustained release of glutamate from photoreceptor synaptic terminals in darkness, a process that is critical for vision. Consistent with this role, Cav1.4 exhibits weak Ca2+-dependent inactivation (CDI)—a negative feedback regulation mediated by Ca2+-bound calmodulin (CaM). CaM binds to a conserved IQ domain in the proximal C-terminal domain of Cav channels, but in Cav1.4, a C-terminal modulatory domain (CTM) disrupts interactions with CaM. Exon 47 encodes a portion of the CTM and is deleted in a Cav1.4 splice variant (Cav1.4Δex47) that is highly expressed in the human retina. Cav1.4Δex47 exhibits CDI and enhanced voltage-dependent activation, similar to that caused by a mutation that is associated with congenital stationary night blindness type 2, in which the CTM is deleted (K1591X). The presence of CDI and very negative activation thresholds in a naturally occurring variant of Cav1.4 are perplexing considering that these properties are expected to be maladaptive for visual signaling and result in night blindness in the case of K1591X. Here we show that Cav1.4Δex47 and K1591X exhibit fundamental differences in their regulation by CaM. In Cav1.4Δex47, CDI requires both the N-terminal (N lobe) and C-terminal (C lobe) lobes of CaM to bind Ca2+, whereas CDI in K1591X is driven mainly by Ca2+ binding to the C lobe. Moreover, the CaM N lobe causes a Ca2+-dependent enhancement of activation of Cav1.4Δex47 but not K1591X. We conclude that the residual CTM in Cav1.4Δex47 enables a form of CaM N lobe regulation of activation and CDI that is absent in K1591X. Interaction with the N lobe of CaM, which is more sensitive to global elevations in cytosolic Ca2+ than the C lobe, may allow Cav1.4Δex47 to be modulated by a wider range of synaptic Ca2+ concentrations than K1591X; this may distinguish the normal physiological function of Cav1.4Δex47 from the pathological consequences of K1591X.
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Affiliation(s)
- Brittany Williams
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA.,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA.,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA
| | - Françoise Haeseleer
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA .,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA.,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA.,Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA.,Department of Neurology, University of Iowa, Iowa City, IA
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27
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Martínez Damonte V, Rodríguez SS, Raingo J. Growth hormone secretagogue receptor constitutive activity impairs voltage-gated calcium channel-dependent inhibitory neurotransmission in hippocampal neurons. J Physiol 2018; 596:5415-5428. [PMID: 30199095 DOI: 10.1113/jp276256] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 09/06/2018] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Presynaptic CaV 2 voltage-gated calcium channels link action potentials arriving at the presynaptic terminal to neurotransmitter release. Hence, their regulation is essential to fine tune brain circuitry. CaV 2 channels are highly sensitive to G protein-coupled receptor (GPCR) modulation. Our previous data indicated that growth hormone secretagogue receptor (GHSR) constitutive activity impairs CaV 2 channels by decreasing their surface density. We present compelling support for the impact of CaV 2.2 channel inhibition by agonist-independent GHSR activity exclusively on GABA release in hippocampal cultures. We found that this selectivity arises from a high reliance of GABA release on CaV 2.2 rather than on CaV 2.1 channels. Our data provide new information on the effects of the ghrelin-GHSR system on synaptic transmission, suggesting a putative physiological role of the constitutive signalling of a GPCR that is expressed at high levels in brain areas with restricted access to its natural agonist. ABSTRACT Growth hormone secretagogue receptor (GHSR) displays high constitutive activity, independent of its endogenous ligand, ghrelin. Unlike ghrelin-induced GHSR activity, the physiological role of GHSR constitutive activity and the mechanisms that underlie GHSR neuronal modulation remain elusive. We previously demonstrated that GHSR constitutive activity modulates presynaptic CaV 2 voltage-gated calcium channels. Here we postulate that GHSR constitutive activity-mediated modulation of CaV 2 channels could be relevant in the hippocampus since this brain area has high GHSR expression but restricted access to ghrelin. We performed whole-cell patch-clamp in hippocampal primary cultures from E16- to E18-day-old C57BL6 wild-type and GHSR-deficient mice after manipulating GHSR expression with lentiviral transduction. We found that GHSR constitutive activity impairs CaV 2.1 and CaV 2.2 native calcium currents and that CaV 2.2 basal impairment leads to a decrease in GABA but not glutamate release. We postulated that this selective effect is related to a higher CaV 2.2 over CaV 2.1 contribution to GABA release (∼40% for CaV 2.2 in wild-type vs. ∼20% in wild-type GHSR-overexpressing cultures). This effect of GHSR constitutive activity is conserved in hippocampal brain slices, where GHSR constitutive activity reduces local GABAergic transmission of the granule cell layer (intra-granule cell inhibitory postsynaptic current (IPSC) size ∼-67 pA in wild-type vs. ∼-100 pA in GHSR-deficient mice), whereas the glutamatergic output from the dentate gyrus to CA3 remains unchanged. In summary, we found that GHSR constitutive activity impairs IPSCs both in hippocampal primary cultures and in brain slices through a CaV 2-dependent mechanism without affecting glutamatergic transmission.
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Affiliation(s)
- Valentina Martínez Damonte
- Multidisciplinary Institute of Cell Biology (IMBICE), National Council of Science and Technology (CONICET), Buenos Aires Comision of Science (CIC) and La Plata University (UNLP), La Plata, Argentina
| | - Silvia Susana Rodríguez
- Multidisciplinary Institute of Cell Biology (IMBICE), National Council of Science and Technology (CONICET), Buenos Aires Comision of Science (CIC) and La Plata University (UNLP), La Plata, Argentina
| | - Jesica Raingo
- Multidisciplinary Institute of Cell Biology (IMBICE), National Council of Science and Technology (CONICET), Buenos Aires Comision of Science (CIC) and La Plata University (UNLP), La Plata, Argentina
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Matrine inhibits itching by lowering the activity of calcium channel. Sci Rep 2018; 8:11328. [PMID: 30054511 PMCID: PMC6063846 DOI: 10.1038/s41598-018-28661-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 06/22/2018] [Indexed: 01/26/2023] Open
Abstract
Sophorae Flavescentis Radix (SFR) is a medicinal herb with many functions that are involved in anti-inflammation, antinociception, and anticancer. SFR is also used to treat a variety of itching diseases. Matrine (MT) is one of the main constituents in SFR and also has the effect of relieving itching, but the antipruritic mechanism is still unclear. Here, we investigated the effect of MT on anti-pruritus. In acute and chronic itch models, MT significantly inhibited the scratching behavior not only in acute itching induced by histamine (His), chloroquine (CQ) and compound 48/80 with a dose-depended manner, but also in the chronic pruritus models of atopic dermatitis (AD) and acetone-ether-water (AEW) in mice. Furthermore, MT could be detected in the blood after intraperitoneal injection (i.p.) and subcutaneous injection (s.c.). Finally, electrophysiological and calcium imaging results showed that MT inhibited the excitatory synaptic transmission from dorsal root ganglion (DRG) to the dorsal horn of the spinal cord by suppressing the presynaptic N-type calcium channel. Taken together, we believe that MT is a novel drug candidate in treating pruritus diseases, especially for histamine-independent and chronic pruritus, which might be attributed to inhibition of the presynaptic N-type calcium channel.
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Dunn TW, Fan X, Ase AR, Séguéla P, Sossin WS. The Ca V2α1 EF-hand F helix tyrosine, a highly conserved locus for GPCR inhibition of Ca V2 channels. Sci Rep 2018; 8:3263. [PMID: 29459734 PMCID: PMC5818475 DOI: 10.1038/s41598-018-21586-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 02/07/2018] [Indexed: 12/16/2022] Open
Abstract
The sensory neuron of Aplysia californica participates in several forms of presynaptic plasticity including homosynaptic depression, heterosynaptic depression, facilitation and the reversal of depression. The calcium channel triggering neurotransmitter release at most synapses is CaV2, consisting of the pore forming α1 subunit (CaV2α1), and auxiliary CaVβ, and CaVα2δ subunits. To determine the role of the CaV2 channel in presynaptic plasticity in Aplysia, we cloned Aplysia CaV2α1, CaVβ, and CaVα2δ and over-expressed the proteins in Aplysia sensory neurons (SN). We show expression of exogenous CaV2α1 in the neurites of cultured Aplysia SN. One proposed mechanism for heterosynaptic depression in Aplysia is through inhibition of CaV2. Here, we demonstrate that heterosynaptic depression of the CaV2 calcium current is inhibited when a channel with a Y-F mutation at the conserved Src phosphorylation site is expressed, showing the strong conservation of this mechanism over evolution. We also show that the Y-F mutation reduces heterosynaptic inhibition of neurotransmitter release, highlighting the physiological importance of this mechanism for the regulation of synaptic efficacy. These results also demonstrate our ability to replace endogenous CaV2 channels with recombinant channels allowing future examination of the structure function relationship of CaV2 in the regulation of transmitter release in this system.
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Affiliation(s)
- Tyler W Dunn
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, H3A 2B4, Canada
| | - Xiaotang Fan
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, H3A 2B4, Canada
| | - Ariel R Ase
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec, H3A 2B4, Canada
| | - Philippe Séguéla
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec, H3A 2B4, Canada
| | - Wayne S Sossin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, H3A 2B4, Canada.
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Jin Y, Dong H, Shi Y, Bian L. Mutually exclusive alternative splicing of pre-mRNAs. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 9:e1468. [PMID: 29423937 DOI: 10.1002/wrna.1468] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Revised: 12/20/2017] [Accepted: 12/20/2017] [Indexed: 12/14/2022]
Abstract
Pre-mRNA alternative splicing is an important mechanism used to expand protein diversity in higher eukaryotes, and mutually exclusive splicing is a specific type of alternative splicing in which only one of the exons in a cluster is included in functional transcripts. The most extraordinary example of this is the Drosophila melanogaster Down's syndrome cell adhesion molecule gene (Dscam), which potentially encodes 38,016 different isoforms through mutually exclusive splicing. Mutually exclusive splicing is a unique and challenging model that can be used to elucidate the evolution, regulatory mechanism, and function of alternative splicing. The use of new approaches has not only greatly expanded the mutually exclusive exome, but has also enabled the systematic analyses of single-cell alternative splicing during development. Furthermore, the identification of long-range RNA secondary structures provides a mechanistic framework for the regulation of mutually exclusive splicing (i.e., Dscam splicing). This article reviews recent insights into the identification, underlying mechanism, and roles of mutually exclusive splicing. This article is categorized under: RNA Processing > Splicing Regulation/Alternative Splicing RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems.
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Affiliation(s)
- Yongfeng Jin
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Haiyang Dong
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Yang Shi
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Lina Bian
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, China
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G-Protein Coupled Receptors Targeted by Analgesic Venom Peptides. Toxins (Basel) 2017; 9:toxins9110372. [PMID: 29144441 PMCID: PMC5705987 DOI: 10.3390/toxins9110372] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 11/13/2017] [Accepted: 11/13/2017] [Indexed: 12/14/2022] Open
Abstract
Chronic pain is a complex and debilitating condition associated with a large personal and socioeconomic burden. Current pharmacological approaches to treating chronic pain such as opioids, antidepressants and anticonvulsants exhibit limited efficacy in many patients and are associated with dose-limiting side effects that hinder their clinical use. Therefore, improved strategies for the pharmacological treatment of pathological pain are urgently needed. G-protein coupled receptors (GPCRs) are ubiquitously expressed on the surface of cells and act to transduce extracellular signals and regulate physiological processes. In the context of pain, numerous and diverse families of GPCRs expressed in pain pathways regulate most aspects of physiological and pathological pain and are thus implicated as potential targets for therapy of chronic pain. In the search for novel compounds that produce analgesia via GPCR modulation, animal venoms offer an enormous and virtually untapped source of potent and selective peptide molecules. While many venom peptides target voltage-gated and ligand-gated ion channels to inhibit neuronal excitability and blunt synaptic transmission of pain signals, only a small proportion are known to interact with GPCRs. Of these, only a few have shown analgesic potential in vivo. Here we review the current state of knowledge regarding venom peptides that target GPCRs to produce analgesia, and their development as therapeutic compounds.
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Src Kinase Inhibition Attenuates Morphine Tolerance without Affecting Reinforcement or Psychomotor Stimulation. Anesthesiology 2017; 127:878-889. [PMID: 28820778 DOI: 10.1097/aln.0000000000001834] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Prolonged opioid administration leads to tolerance characterized by reduced analgesic potency. Pain management is additionally compromised by the hedonic effects of opioids, the cause of their misuse. The multifunctional protein β-arrestin2 regulates the hedonic effects of morphine and participates in tolerance. These actions might reflect µ opioid receptor up-regulation through reduced endocytosis. β-Arrestin2 also recruits kinases to µ receptors. We explored the role of Src kinase in morphine analgesic tolerance, locomotor stimulation, and reinforcement in C57BL/6 mice. METHODS Analgesic (tail withdrawal latency; percentage of maximum possible effect, n = 8 to 16), locomotor (distance traveled, n = 7 to 8), and reinforcing (conditioned place preference, n = 7 to 8) effects of morphine were compared in wild-type, µ, µ, and β-arrestin2 mice. The influence of c-Src inhibitors dasatinib (n = 8) and PP2 (n = 12) was examined. RESULTS Analgesia in morphine-treated wild-type mice exhibited tolerance, declining by day 10 to a median of 62% maximum possible effect (interquartile range, 29 to 92%). Tolerance was absent from mice receiving dasatinib. Tolerance was enhanced in µ mice (34% maximum possible effect; interquartile range, 5 to 52% on day 5); dasatinib attenuated tolerance (100% maximum possible effect; interquartile range, 68 to 100%), as did PP2 (91% maximum possible effect; interquartile range, 78 to 100%). By contrast, c-Src inhibition affected neither morphine-evoked locomotor stimulation nor reinforcement. Remarkably, dasatinib not only attenuated tolerance but also reversed established tolerance in µ mice. CONCLUSIONS The ability of c-Src inhibitors to inhibit tolerance, thereby restoring analgesia, without altering the hedonic effect of morphine, makes c-Src inhibitors promising candidates as adjuncts to opioid analgesics.
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Chen W, Ennes HS, McRoberts JA, Marvizón JC. Mechanisms of μ-opioid receptor inhibition of NMDA receptor-induced substance P release in the rat spinal cord. Neuropharmacology 2017; 128:255-268. [PMID: 29042318 DOI: 10.1016/j.neuropharm.2017.10.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 09/21/2017] [Accepted: 10/11/2017] [Indexed: 01/17/2023]
Abstract
The interaction between NMDA receptors and μ-opioid receptors in primary afferent terminals was studied by using NMDA to induce substance P release, measured as neurokinin 1 receptor internalization. In rat spinal cord slices, the μ-opioid receptor agonists morphine, DAMGO and endomorphin-2 inhibited NMDA-induced substance P release, whereas the antagonist CTAP right-shifted the concentration response of DAMGO. In vivo, substance P release induced by intrathecal NMDA after priming with BDNF was inhibited by DAMGO. ω-Conotoxins MVIIC and GVIA inhibited about half of the NMDA-induced substance P release, showing that it was partially mediated by the opening of voltage-gated calcium (Cav) channels. In contrast, DAMGO or ω-conotoxins did not inhibit capsaicin-induced substance P release. In cultured DRG neurons, DAMGO but not ω-conotoxin inhibited NMDA-induced increases in intracellular calcium, indicating that μ-opioid receptors can inhibit NMDA receptor function by mechanisms other than inactivation of Cav channels. Moreover, DAMGO decreased the ω-conotoxin-insensitive component of the substance P release. Potent inhibition by ifenprodil showed that these NMDA receptors have the NR2B subunit. Activators of adenylyl cyclase and protein kinase A (PKA) induced substance P release and this was decreased by the NMDA receptor blocker MK-801 and by DAMGO. Conversely, inhibitors of adenylyl cyclase and PKA, but not of protein kinase C, decreased NMDA-induced substance P release. Hence, these NMDA receptors are positively modulated by the adenylyl cyclase-PKA pathway, which is inhibited by μ-opioid receptors. In conclusion, μ-opioid receptors inhibit NMDA receptor-induced substance P release through Cav channel inactivation and adenylyl cyclase inhibition.
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Affiliation(s)
- Wenling Chen
- Veteran Affairs Greater Los Angeles Healthcare System, 11310 Wilshire Blvd., Building 115, Los Angeles, CA 90073, USA; Vatche and Tamar Manoukian Division of Digestive Diseases, 900 Veterans Ave., Warren Hall Building, Department of Medicine, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA 90095, USA.
| | - Helena S Ennes
- Vatche and Tamar Manoukian Division of Digestive Diseases, 900 Veterans Ave., Warren Hall Building, Department of Medicine, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA 90095, USA.
| | - James A McRoberts
- Vatche and Tamar Manoukian Division of Digestive Diseases, 900 Veterans Ave., Warren Hall Building, Department of Medicine, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA 90095, USA.
| | - Juan Carlos Marvizón
- Veteran Affairs Greater Los Angeles Healthcare System, 11310 Wilshire Blvd., Building 115, Los Angeles, CA 90073, USA; Vatche and Tamar Manoukian Division of Digestive Diseases, 900 Veterans Ave., Warren Hall Building, Department of Medicine, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA 90095, USA.
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Mustafá ER, López Soto EJ, Martínez Damonte V, Rodríguez SS, Lipscombe D, Raingo J. Constitutive activity of the Ghrelin receptor reduces surface expression of voltage-gated Ca 2+ channels in a Ca Vβ-dependent manner. J Cell Sci 2017; 130:3907-3917. [PMID: 29038230 DOI: 10.1242/jcs.207886] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 10/04/2017] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated Ca2+ (CaV) channels couple membrane depolarization to Ca2+ influx, triggering a range of Ca2+-dependent cellular processes. CaV channels are, therefore, crucial in shaping neuronal activity and function, depending on their individual temporal and spatial properties. Furthermore, many neurotransmitters and drugs that act through G protein coupled receptors (GPCRs), modulate neuronal activity by altering the expression, trafficking, or function of CaV channels. GPCR-dependent mechanisms that downregulate CaV channel expression levels are observed in many neurons but are, by comparison, less studied. Here we show that the growth hormone secretagogue receptor type 1a (GHSR), a GPCR, can inhibit the forwarding trafficking of several CaV subtypes, even in the absence of agonist. This constitutive form of GPCR inhibition of CaV channels depends on the presence of a CaVβ subunit. CaVβ subunits displace CaVα1 subunits from the endoplasmic reticulum. The actions of GHSR on CaV channels trafficking suggest a role for this signaling pathway in brain areas that control food intake, reward, and learning and memory.
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Affiliation(s)
- Emilio R Mustafá
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE), Universidad Nacional de La Plata - Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comisión de Investigaciones de la Provincia de buenos Aires (CIC) Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
| | - Eduardo J López Soto
- Department of Neuroscience, Brown University; Sidney E. Frank Hall for Life Sciences, 185 Meeting Street, Providence, Rhode Island 02912, USA
| | - Valentina Martínez Damonte
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE), Universidad Nacional de La Plata - Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comisión de Investigaciones de la Provincia de buenos Aires (CIC) Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
| | - Silvia S Rodríguez
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE), Universidad Nacional de La Plata - Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comisión de Investigaciones de la Provincia de buenos Aires (CIC) Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
| | - Diane Lipscombe
- Department of Neuroscience, Brown University; Sidney E. Frank Hall for Life Sciences, 185 Meeting Street, Providence, Rhode Island 02912, USA
| | - Jesica Raingo
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE), Universidad Nacional de La Plata - Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comisión de Investigaciones de la Provincia de buenos Aires (CIC) Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
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Allen SE, Toro CP, Andrade A, López-Soto EJ, Denome S, Lipscombe D. Cell-Specific RNA Binding Protein Rbfox2 Regulates Ca V2.2 mRNA Exon Composition and Ca V2.2 Current Size. eNeuro 2017; 4:ENEURO.0332-16.2017. [PMID: 29067356 PMCID: PMC5633781 DOI: 10.1523/eneuro.0332-16.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 09/14/2017] [Accepted: 09/21/2017] [Indexed: 01/25/2023] Open
Abstract
The majority of multiexon mammalian genes contain alternatively spliced exons that have unique expression patterns in different cell populations and that have important cell functions. The expression profiles of alternative exons are controlled by cell-specific splicing factors that can promote exon inclusion or exon skipping but with few exceptions we do not know which specific splicing factors control the expression of alternatively spliced exons of known biological function. Many ion channel genes undergo extensive alternative splicing including Cacna1b that encodes the voltage-gated CaV2.2 α1 subunit. Alternatively spliced exon 18a in Cacna1b RNA encodes 21 amino acids in the II-III loop of CaV2.2, and its expression differs across the nervous system and over development. Genome-wide, protein-RNA binding analyses coupled to high-throughput RNA sequencing show that RNA binding Fox (Rbfox) proteins associate with CaV2.2 (Cacna1b) pre-mRNAs. Here, we link Rbfox2 to suppression of e18a. We show increased e18a inclusion in CaV2.2 mRNAs: (1) after siRNA knockdown of Rbfox2 in a neuronal cell line and (2) in RNA from sympathetic neurons of adult compared to early postnatal mice. By immunoprecipitation of Rbfox2-RNA complexes followed by qPCR, we demonstrate reduced Rbfox2 binding upstream of e18a in RNA from sympathetic neurons of adult compared to early postnatal mice. CaV2.2 currents in cell lines and in sympathetic neurons expressing only e18a-CaV2.2 are larger compared to currents from those expressing only Δ18a-CaV2.2. We conclude that Rbfox2 represses e18a inclusion during pre-mRNA splicing of CaV2.2, limiting the size of CaV2.2 currents early in development in certain neuronal populations.
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MESH Headings
- Action Potentials/genetics
- Animals
- Animals, Newborn
- Calcium Channels, N-Type/genetics
- Calcium Channels, N-Type/metabolism
- Cells, Cultured
- Exons/genetics
- Female
- Gene Expression Regulation, Developmental/genetics
- Humans
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Models, Molecular
- Neurons/physiology
- RNA Splicing Factors/genetics
- RNA Splicing Factors/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Rats
- Superior Cervical Ganglion/cytology
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Affiliation(s)
- Summer E. Allen
- Department of Neuroscience, and the Brown Institute for Brain Science, Brown University, Providence, RI 02912
| | - Cecilia P. Toro
- Department of Biology, Linfield College, McMinnville, OR 97128
| | - Arturo Andrade
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824
| | - Eduardo J. López-Soto
- Department of Neuroscience, and the Brown Institute for Brain Science, Brown University, Providence, RI 02912
| | - Sylvia Denome
- Department of Neuroscience, and the Brown Institute for Brain Science, Brown University, Providence, RI 02912
| | - Diane Lipscombe
- Department of Neuroscience, and the Brown Institute for Brain Science, Brown University, Providence, RI 02912
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36
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Morphine activation of mu opioid receptors causes disinhibition of neurons in the ventral tegmental area mediated by β-arrestin2 and c-Src. Sci Rep 2017; 7:9969. [PMID: 28855588 PMCID: PMC5577270 DOI: 10.1038/s41598-017-10360-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 08/09/2017] [Indexed: 12/31/2022] Open
Abstract
The tyrosine kinase, c-Src, participates in mu opioid receptor (MOP) mediated inhibition in sensory neurons in which β-arrestin2 (β-arr2) is implicated in its recruitment. Mice lacking β-arr2 exhibit increased sensitivity to morphine reinforcement; however, whether β-arr2 and/or c-Src participate in the actions of opioids in neurons within the reward pathway is unknown. It is also unclear whether morphine acts exclusively through MOPs, or involves delta opioid receptors (DOPs). We examined the involvement of MOPs, DOPs, β-arr2 and c-Src in the inhibition by morphine of GABAergic inhibitory postsynaptic currents (IPSCs) recorded from neurons in the mouse ventral tegmental area. Morphine inhibited spontaneous IPSC frequency, mainly through MOPs, with only a negligible effect remaining in MOP−/− neurons. However, a reduction in the inhibition by morphine for DOP−/− c.f. WT neurons and a DPDPE-induced decrease of IPSC frequency revealed a role for DOPs. The application of the c-Src inhibitor, PP2, to WT neurons also reduced inhibition by morphine, while the inactive PP3, and the MEK inhibitor, SL327, had no effect. Inhibition of IPSC frequency by morphine was also reduced in β-arr2−/− neurons in which PP2 caused no further reduction. These data suggest that inhibition of IPSCs by morphine involves a β-arr2/c-Src mediated mechanism.
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37
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Partridge LMM, Carter DA. Novel Rbfox2 isoforms associated with alternative exon usage in rat cortex and suprachiasmatic nucleus. Sci Rep 2017; 7:9929. [PMID: 28855650 PMCID: PMC5577181 DOI: 10.1038/s41598-017-10535-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 08/09/2017] [Indexed: 12/20/2022] Open
Abstract
Transcriptome diversity in adult neurons is partly mediated by RNA binding proteins (RBPs), including the RBFOX factors. RBFOX3/NeuN, a neuronal maturity marker, is strangely depleted in suprachiasmatic nucleus (SCN) neurons, and may be compensated by a change in Rbfox2 expression. In this study, we found no superficial changes in Rbfox2 expression in the SCN, but mRNA population analysis revealed a distinct SCN transcript profile that includes multiple novel Rbfox2 isoforms. Of eleven isoforms in SCN and cerebral cortex that exhibit exon variation across two protein domains, we found a 3-fold higher abundance of a novel (‘−12–40’) C-terminal domain (CTD)-variant in the SCN. This isoform embraces an alternative reading frame that imparts a 50% change in CTD protein sequence, and functional impairment of exon 7 exclusion activity in a RBFOX2-target, the L-type calcium channel gene, Cacna1c. We have also demonstrated functional correlates in SCN gene transcripts; inclusion of Cacna1c exon 7, and also exclusion of both NMDA receptor gene Grin1 exon 4, and Enah exon 12, all consistent with a change in SCN RBFOX activity. The demonstrated regional diversity of Rbfox2 in adult brain highlights the functional adaptability of this RBP, enabling neuronal specialization, and potentially responding to disease-related neuronal dysfunction.
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Affiliation(s)
| | - D A Carter
- School of Biosciences, Cardiff University, Cardiff, UK.
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38
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Castro J, Harrington AM, Garcia-Caraballo S, Maddern J, Grundy L, Zhang J, Page G, Miller PE, Craik DJ, Adams DJ, Brierley SM. α-Conotoxin Vc1.1 inhibits human dorsal root ganglion neuroexcitability and mouse colonic nociception via GABA B receptors. Gut 2017; 66:1083-1094. [PMID: 26887818 PMCID: PMC5532460 DOI: 10.1136/gutjnl-2015-310971] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 12/22/2015] [Accepted: 01/14/2016] [Indexed: 01/29/2023]
Abstract
OBJECTIVE α-Conotoxin Vc1.1 is a small disulfide-bonded peptide from the venom of the marine cone snail Conus victoriae. Vc1.1 has antinociceptive actions in animal models of neuropathic pain, but its applicability to inhibiting human dorsal root ganglion (DRG) neuroexcitability and reducing chronic visceral pain (CVP) is unknown. DESIGN We determined the inhibitory actions of Vc1.1 on human DRG neurons and on mouse colonic sensory afferents in healthy and chronic visceral hypersensitivity (CVH) states. In mice, visceral nociception was assessed by neuronal activation within the spinal cord in response to noxious colorectal distension (CRD). Quantitative-reverse-transcription-PCR, single-cell-reverse-transcription-PCR and immunohistochemistry determined γ-aminobutyric acid receptor B (GABABR) and voltage-gated calcium channel (CaV2.2, CaV2.3) expression in human and mouse DRG neurons. RESULTS Vc1.1 reduced the excitability of human DRG neurons, whereas a synthetic Vc1.1 analogue that is inactive at GABABR did not. Human DRG neurons expressed GABABR and its downstream effector channels CaV2.2 and CaV2.3. Mouse colonic DRG neurons exhibited high GABABR, CaV2.2 and CaV2.3 expression, with upregulation of the CaV2.2 exon-37a variant during CVH. Vc1.1 inhibited mouse colonic afferents ex vivo and nociceptive signalling of noxious CRD into the spinal cord in vivo, with greatest efficacy observed during CVH. A selective GABABR antagonist prevented Vc1.1-induced inhibition, whereas blocking both CaV2.2 and CaV2.3 caused inhibition comparable with Vc1.1 alone. CONCLUSIONS Vc1.1-mediated activation of GABABR is a novel mechanism for reducing the excitability of human DRG neurons. Vc1.1-induced activation of GABABR on the peripheral endings of colonic afferents reduces nociceptive signalling. The enhanced antinociceptive actions of Vc1.1 during CVH suggest it is a novel candidate for the treatment for CVP.
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Affiliation(s)
- Joel Castro
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Andrea M Harrington
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Sonia Garcia-Caraballo
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Jessica Maddern
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Luke Grundy
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | | | - Guy Page
- Anabios, San Diego, California, USA
| | | | - David J Craik
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia
| | - David J Adams
- Illawarra Health & Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Stuart M Brierley
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
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39
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Sadeghi M, McArthur JR, Finol-Urdaneta RK, Adams DJ. Analgesic conopeptides targeting G protein-coupled receptors reduce excitability of sensory neurons. Neuropharmacology 2017; 127:116-123. [PMID: 28533165 DOI: 10.1016/j.neuropharm.2017.05.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 05/16/2017] [Accepted: 05/18/2017] [Indexed: 01/28/2023]
Abstract
Conotoxins (conopeptides) are a diverse group of peptides isolated from the venom of marine cone snails. Conus peptides modulate pain by interacting with voltage-gated ion channels and G protein-coupled receptors (GPCRs). Opiate drugs targeting GPCRs have long been used, nonetheless, many undesirable side effects associated with opiates have been observed including addiction. Consequently, alternative avenues to pain management are a largely unmet need. It has been shown that various voltage-gated calcium channels (VGCCs) respond to GPCR modulation. Thus, regulation of VGCCs by GPCRs has become a valuable alternative in the management of pain. In this review, we focus on analgesic conotoxins that exert their effects via GPCR-mediated inhibition of ion channels involved in nociception and pain transmission. Specifically, α-conotoxin Vc1.1 activation of GABAB receptors and inhibition of voltage-gated calcium channels as a novel mechanism for reducing the excitability of dorsal root ganglion neurons is described. Vc1.1 and other α-conotoxins have been shown to be analgesic in different animal models of chronic pain. This review will outline the functional effects of conopeptide modulation of GPCRs and how their signalling is translated to downstream components of the pain pathways. Where available we present the proposed signalling mechanisms that couples metabotropic receptor activation to their downstream effectors to produce analgesia. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Mahsa Sadeghi
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, 2522, Australia
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, 2522, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, 2522, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, 2522, Australia.
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40
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Targeting human Mas-related G protein-coupled receptor X1 to inhibit persistent pain. Proc Natl Acad Sci U S A 2017; 114:E1996-E2005. [PMID: 28223516 DOI: 10.1073/pnas.1615255114] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Human Mas-related G protein-coupled receptor X1 (MRGPRX1) is a promising target for pain inhibition, mainly because of its restricted expression in nociceptors within the peripheral nervous system. However, constrained by species differences across Mrgprs, drug candidates that activate MRGPRX1 do not activate rodent receptors, leaving no responsive animal model to test the effect on pain in vivo. Here, we generated a transgenic mouse line in which we replaced mouse Mrgprs with human MrgprX1 This humanized mouse allowed us to characterize an agonist [bovine adrenal medulla 8-22 (BAM8-22)] and a positive allosteric modulator (PAM), ML382, of MRGPRX1. Cellular studies suggested that ML382 enhances the ability of BAM8-22 to inhibit high-voltage-activated Ca2+ channels and attenuate spinal nociceptive transmission. Importantly, both BAM8-22 and ML382 effectively attenuated evoked, persistent, and spontaneous pain without causing obvious side effects. Notably, ML382 by itself attenuated both evoked pain hypersensitivity and spontaneous pain in MrgprX1 mice after nerve injury without acquiring coadministration of an exogenous agonist. Our findings suggest that humanized MrgprX1 mice provide a promising preclinical model and that activating MRGPRX1 is an effective way to treat persistent pain.
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41
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Agosti F, Cordisco Gonzalez S, Martinez Damonte V, Tolosa MJ, Di Siervi N, Schioth HB, Davio C, Perello M, Raingo J. Melanocortin 4 receptor constitutive activity inhibits L-type voltage-gated calcium channels in neurons. Neuroscience 2017; 346:102-112. [PMID: 28093215 DOI: 10.1016/j.neuroscience.2017.01.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 12/16/2016] [Accepted: 01/05/2017] [Indexed: 11/19/2022]
Abstract
The melanocortin 4 receptor (MC4R) is a G protein-coupled receptor (GPCR) that is expressed in several brain nuclei playing a crucial role in the regulation of energy balance controlling the homeostasis of the organism. It displays both agonist-evoked and constitutive activity, and moreover, it can couple to different G proteins. Most of the research on MC4R has been focused on agonist-induced activity, while the molecular and cellular basis of MC4R constitutive activity remains scarcely studied. We have previously shown that neuronal N-type voltage-gated calcium channels (CaV2.2) are inhibited by MC4R agonist-dependent activation, while the CaV subtypes that carry L- and P/Q-type current are not. Here, we tested the hypothesis that MC4R constitutive activity can affect CaV, with focus on the channel subtypes that can control transcriptional activity coupled to depolarization (L-type, CaV1.2/1.3) and neurotransmitter release (N- and P/Q-type, CaV2.2 and CaV2.1). We found that MC4R constitutive activity inhibits specifically CaV1.2/1.3 and CaV2.1 subtypes of CaV. We also explored the signaling pathways mediating this inhibition, and thus propose that agonist-dependent and basal MC4R activation modes signal differentially through Gs and Gi/o pathways to impact on different CaV subtypes. In addition, we found that chronic incubation with MC4R endogenous inverse agonist, agouti and agouti-related peptide (AgRP), occludes CaV inhibition in a cell line and in amygdaloid complex cultured neurons as well. Thus, we define new mechanisms of control of the main mediators of depolarization-induced calcium entry into neurons by a GPCR that displays constitutive activity.
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Affiliation(s)
- F Agosti
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - S Cordisco Gonzalez
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - V Martinez Damonte
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - M J Tolosa
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - N Di Siervi
- Instituto de Investigaciones Farmacológicas, ININFA, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, Buenos Aires, Argentina
| | - H B Schioth
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Uppsala, Sweden
| | - C Davio
- Instituto de Investigaciones Farmacológicas, ININFA, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, Buenos Aires, Argentina
| | - M Perello
- Neurophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - J Raingo
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
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42
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François A, Scherrer G. Delta Opioid Receptor Expression and Function in Primary Afferent Somatosensory Neurons. Handb Exp Pharmacol 2017; 247:87-114. [PMID: 28993838 DOI: 10.1007/164_2017_58] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The functional diversity of primary afferent neurons of the dorsal root ganglia (DRG) generates a variety of qualitatively and quantitatively distinct somatosensory experiences, from shooting pain to pleasant touch. In recent years, the identification of dozens of genetic markers specifically expressed by subpopulations of DRG neurons has dramatically improved our understanding of this diversity and provided the tools to manipulate their activity and uncover their molecular identity and function. Opioid receptors have long been known to be expressed by discrete populations of DRG neurons, in which they regulate cell excitability and neurotransmitter release. We review recent insights into the identity of the DRG neurons that express the delta opioid receptor (DOR) and the ion channel mechanisms that DOR engages in these cells to regulate sensory input. We highlight recent findings derived from DORGFP reporter mice and from in situ hybridization and RNA sequencing studies in wild-type mice that revealed DOR presence in cutaneous mechanosensory afferents eliciting touch and implicated in tactile allodynia. Mechanistically, we describe how DOR modulates opening of voltage-gated calcium channels (VGCCs) to control glutamatergic neurotransmission between somatosensory neurons and postsynaptic neurons in the spinal cord dorsal horn. We additionally discuss other potential signaling mechanisms, including those involving potassium channels, which DOR may engage to fine tune somatosensation. We conclude by discussing how this knowledge may explain the analgesic properties of DOR agonists against mechanical pain and uncovers an unanticipated specialized function for DOR in cutaneous mechanosensation.
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Affiliation(s)
- Amaury François
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford Neurosciences Institute, Stanford University School of Medicine, Palo Alto, CA, USA.,Department of Molecular and Cellular Physiology, Stanford Neurosciences Institute, Stanford University School of Medicine, Palo Alto, CA, USA.,Department of Neurosurgery, Stanford Neurosciences Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Grégory Scherrer
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford Neurosciences Institute, Stanford University School of Medicine, Palo Alto, CA, USA. .,Department of Molecular and Cellular Physiology, Stanford Neurosciences Institute, Stanford University School of Medicine, Palo Alto, CA, USA. .,Department of Neurosurgery, Stanford Neurosciences Institute, Stanford University School of Medicine, Palo Alto, CA, USA.
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43
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Andrade A, Hope J, Allen A, Yorgan V, Lipscombe D, Pan JQ. A rare schizophrenia risk variant of CACNA1I disrupts Ca V3.3 channel activity. Sci Rep 2016; 6:34233. [PMID: 27756899 PMCID: PMC5069464 DOI: 10.1038/srep34233] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 09/07/2016] [Indexed: 02/04/2023] Open
Abstract
CACNA1I is a candidate schizophrenia risk gene. It encodes the pore-forming human CaV3.3 α1 subunit, a subtype of voltage-gated calcium channel that contributes to T-type currents. Recently, two de novo missense variations, T797M and R1346H, of hCaV3.3 were identified in individuals with schizophrenia. Here we show that R1346H, but not T797M, is associated with lower hCaV3.3 protein levels, reduced glycosylation, and lower membrane surface levels of hCaV3.3 when expressed in human cell lines compared to wild-type. Consistent with our biochemical analyses, whole-cell hCaV3.3 currents in cells expressing the R1346H variant were ~50% of those in cells expressing WT hCaV3.3, and neither R1346H nor T797M altered channel biophysical properties. Employing the NEURON simulation environment, we found that reducing hCaV3.3 current densities by 22% or more eliminates rebound bursting in model thalamic reticular nucleus (TRN) neurons. Our analyses suggest that a single copy of Chr22: 39665939G > A CACNA1I has the capacity to disrupt CaV3.3 channel-dependent functions, including rebound bursting in TRN neurons, with potential implications for schizophrenia pathophysiology.
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Affiliation(s)
- A Andrade
- Department of Biological Sciences, College of Life Sciences and Agriculture, University of New Hampshire, Durham, NH 03824, USA.,Brown Institute for Brain Science, Providence, RI 02912, USA
| | - J Hope
- Stanley Center of Psychiatric Research, Broad Institute of Harvard and MIT, 75 Ames Street, Cambridge, MA 02142, USA
| | - A Allen
- Stanley Center of Psychiatric Research, Broad Institute of Harvard and MIT, 75 Ames Street, Cambridge, MA 02142, USA
| | - V Yorgan
- Brown Institute for Brain Science, Providence, RI 02912, USA
| | - D Lipscombe
- Brown Institute for Brain Science, Providence, RI 02912, USA
| | - J Q Pan
- Stanley Center of Psychiatric Research, Broad Institute of Harvard and MIT, 75 Ames Street, Cambridge, MA 02142, USA
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44
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Lipscombe D, Andrade A. Calcium Channel CaVα₁ Splice Isoforms - Tissue Specificity and Drug Action. Curr Mol Pharmacol 2016; 8:22-31. [PMID: 25966698 DOI: 10.2174/1874467208666150507103215] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Revised: 01/20/2015] [Accepted: 04/20/2015] [Indexed: 12/11/2022]
Abstract
Voltage-gated calcium ion channels are essential for numerous biological functions of excitable cells and there is wide spread appreciation of their importance as drug targets in the treatment of many disorders including those of cardiovascular and nervous systems. Each Cacna1 gene has the potential to generate a number of structurally, functionally, and in some cases pharmacologically unique CaVα1 subunits through alternative pre-mRNA splicing and the use of alternate promoters. Analyses of rapidly emerging deep sequencing data for a range of human tissue transcriptomes contain information to quantify tissue-specific and alternative exon usage patterns for Cacna1 genes. Cellspecific actions of nuclear DNA and RNA binding proteins control the use of alternate promoters and the selection of alternate exons during pre-mRNA splicing, and they determine the spectrum of protein isoforms expressed within different types of cells. Amino acid compositions within discrete protein domains can differ substantially among CaV isoforms expressed in different tissues, and such differences may be greater than those that exist across CaV channel homologs of closely related species. Here we highlight examples of CaV isoforms that have unique expression patterns and that exhibit different pharmacological sensitivities. Knowledge of expression patterns of CaV isoforms in different human tissues, cell populations, ages, and disease states should inform strategies aimed at developing the next generation of CaV channel inhibitors and agonists with improved tissue-specificity.
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Affiliation(s)
- Diane Lipscombe
- Department of Neuroscience, Brown University. Providence, RI, USA.
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45
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Alternative Splicing in Ca(V)2.2 Regulates Neuronal Trafficking via Adaptor Protein Complex-1 Adaptor Protein Motifs. J Neurosci 2016; 35:14636-52. [PMID: 26511252 DOI: 10.1523/jneurosci.3034-15.2015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
N-type voltage-gated calcium (Ca(V)2.2) channels are expressed in neurons and targeted to the plasma membrane of presynaptic terminals, facilitating neurotransmitter release. Here, we find that the adaptor protein complex-1 (AP-1) mediates trafficking of Ca(V)2.2 from the trans-Golgi network to the cell surface. Examination of splice variants of Ca(V)2.2, containing either exon 37a (selectively expressed in nociceptors) or 37b in the proximal C terminus, reveal that canonical AP-1 binding motifs, YxxΦ and [DE]xxxL[LI], present only in exon 37a, enhance intracellular trafficking of exon 37a-containing Ca(V)2.2 to the axons and plasma membrane of rat DRG neurons. Finally, we identify differential effects of dopamine-2 receptor (D2R) and its agonist-induced activation on trafficking of Ca(V)2.2 isoforms. D2R slowed the endocytosis of Ca(V)2.2 containing exon 37b, but not exon 37a, and activation by the agonist quinpirole reversed the effect of the D2R. Our work thus reveals key mechanisms involved in the trafficking of N-type calcium channels.
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46
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Injury-specific functional alteration of N-type voltage-gated calcium channels in synaptic transmission of primary afferent C-fibers in the rat spinal superficial dorsal horn. Eur J Pharmacol 2016; 772:11-21. [DOI: 10.1016/j.ejphar.2015.12.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 12/15/2015] [Accepted: 12/16/2015] [Indexed: 11/17/2022]
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Delaney AJ, Crane JW. Presynaptic GABAB receptors reduce transmission at parabrachial synapses in the lateral central amygdala by inhibiting N-type calcium channels. Sci Rep 2016; 6:19255. [PMID: 26755335 PMCID: PMC4709695 DOI: 10.1038/srep19255] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 12/07/2015] [Indexed: 11/20/2022] Open
Abstract
The nocioceptive information carried by neurons of the pontine parabrachial nucleus to neurons of the lateral division of the central amydala (CeA-L) is thought to contribute to the affective components of pain and is required for the formation of conditioned-fear memories. Importantly, excitatory transmission between parabrachial axon terminals and CeA-L neurons can be inhibited by a number of presynaptic receptors linked to Gi/o-type G-proteins, including α2-adrenoceptors and GABAB receptors. While the intracellular signalling pathway responsible for α2-adrenoceptor inhibition of synaptic transmission at this synapse is known, the mechanism by which GABAB receptors inhibits transmission has not been determined. The present study demonstrates that activation of presynaptic GABAB receptors reduces excitatory transmission between parabrachial axon terminals and CeA-L neurons by inhibiting N-type calcium channels. While the involvement of Gβγ subunits in mediating the inhibitory effects of GABAB receptors on N-type calcium channels is unclear, this inhibition does not involve Gβγ-independent activation of pp60C-src tyrosine kinase. The results of this study further enhance our understanding of the modulation of the excitatory input from parabrachial axon terminals to CeA-L neurons and indicate that presynaptic GABAB receptors at this synapse could be valuable therapeutic targets for the treatment of fear- and pain-related disorders.
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Affiliation(s)
- A J Delaney
- School of Biomedical Sciences, Charles Sturt University, NSW, Australia
| | - J W Crane
- School of Biomedical Sciences, Charles Sturt University, NSW, Australia
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Berecki G, Motin L, Adams DJ. Voltage-Gated R-Type Calcium Channel Inhibition via Human μ-, δ-, and κ-opioid Receptors Is Voltage-Independently Mediated by Gβγ Protein Subunits. Mol Pharmacol 2015; 89:187-96. [PMID: 26490245 DOI: 10.1124/mol.115.101154] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/19/2015] [Indexed: 01/07/2023] Open
Abstract
Elucidating the mechanisms that modulate calcium channels via opioid receptor activation is fundamental to our understanding of both pain perception and how opioids modulate pain. Neuronal voltage-gated N-type calcium channels (Cav2.2) are inhibited by activation of G protein-coupled opioid receptors (ORs). However, inhibition of R-type (Cav2.3) channels by μ- or κ-ORs is poorly defined and has not been reported for δ-ORs. To investigate such interactions, we coexpressed human μ-, δ-, or κ-ORs with human Cav2.3 or Cav2.2 in human embryonic kidney 293 cells and measured depolarization-activated Ba(2+) currents (IBa). Selective agonists of μ-, δ-, and κ-ORs inhibited IBa through Cav2.3 channels by 35%. Cav2.2 channels were inhibited to a similar extent by κ-ORs, but more potently (60%) via μ- and δ-ORs. Antagonists of δ- and κ-ORs potentiated IBa amplitude mediated by Cav2.3 and Cav2.2 channels. Consistent with G protein βγ (Gβγ) interaction, modulation of Cav2.2 was primarily voltage-dependent and transiently relieved by depolarizing prepulses. In contrast, Cav2.3 modulation was voltage-independent and unaffected by depolarizing prepulses. However, Cav2.3 inhibition was sensitive to pertussis toxin and to intracellular application of guanosine 5'-[β-thio]diphosphate trilithium salt and guanosine 5'-[γ-thio]triphosphate tetralithium salt. Coexpression of Gβγ-specific scavengers-namely, the carboxyl terminus of the G protein-coupled receptor kinase 2 or membrane-targeted myristoylated-phosducin-attenuated or abolished Cav2.3 modulation. Our study reveals the diversity of OR-mediated signaling at Cav2 channels and identifies neuronal Cav2.3 channels as potential targets for opioid analgesics. Their novel modulation is dependent on pre-existing OR activity and mediated by membrane-delimited Gβγ subunits in a voltage-independent manner.
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Affiliation(s)
- Géza Berecki
- Health Innovations Research Institute, RMIT University, Melbourne, Victoria, Australia
| | - Leonid Motin
- Health Innovations Research Institute, RMIT University, Melbourne, Victoria, Australia
| | - David J Adams
- Health Innovations Research Institute, RMIT University, Melbourne, Victoria, Australia
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Zamponi GW, Striessnig J, Koschak A, Dolphin AC. The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential. Pharmacol Rev 2015; 67:821-70. [PMID: 26362469 PMCID: PMC4630564 DOI: 10.1124/pr.114.009654] [Citation(s) in RCA: 704] [Impact Index Per Article: 78.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Voltage-gated calcium channels are required for many key functions in the body. In this review, the different subtypes of voltage-gated calcium channels are described and their physiologic roles and pharmacology are outlined. We describe the current uses of drugs interacting with the different calcium channel subtypes and subunits, as well as specific areas in which there is strong potential for future drug development. Current therapeutic agents include drugs targeting L-type Ca(V)1.2 calcium channels, particularly 1,4-dihydropyridines, which are widely used in the treatment of hypertension. T-type (Ca(V)3) channels are a target of ethosuximide, widely used in absence epilepsy. The auxiliary subunit α2δ-1 is the therapeutic target of the gabapentinoid drugs, which are of value in certain epilepsies and chronic neuropathic pain. The limited use of intrathecal ziconotide, a peptide blocker of N-type (Ca(V)2.2) calcium channels, as a treatment of intractable pain, gives an indication that these channels represent excellent drug targets for various pain conditions. We describe how selectivity for different subtypes of calcium channels (e.g., Ca(V)1.2 and Ca(V)1.3 L-type channels) may be achieved in the future by exploiting differences between channel isoforms in terms of sequence and biophysical properties, variation in splicing in different target tissues, and differences in the properties of the target tissues themselves in terms of membrane potential or firing frequency. Thus, use-dependent blockers of the different isoforms could selectively block calcium channels in particular pathologies, such as nociceptive neurons in pain states or in epileptic brain circuits. Of important future potential are selective Ca(V)1.3 blockers for neuropsychiatric diseases, neuroprotection in Parkinson's disease, and resistant hypertension. In addition, selective or nonselective T-type channel blockers are considered potential therapeutic targets in epilepsy, pain, obesity, sleep, and anxiety. Use-dependent N-type calcium channel blockers are likely to be of therapeutic use in chronic pain conditions. Thus, more selective calcium channel blockers hold promise for therapeutic intervention.
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Affiliation(s)
- Gerald W Zamponi
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Joerg Striessnig
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Alexandra Koschak
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Annette C Dolphin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
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Wang X, Xu X, Lu X, Zhang Y, Pan W. Transcriptome Bioinformatical Analysis of Vertebrate Stages of Schistosoma japonicum Reveals Alternative Splicing Events. PLoS One 2015; 10:e0138470. [PMID: 26407301 PMCID: PMC4583307 DOI: 10.1371/journal.pone.0138470] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/31/2015] [Indexed: 01/22/2023] Open
Abstract
Alternative splicing is a molecular process that contributes greatly to the diversification of proteome and to gene functions. Understanding the mechanisms of stage-specific alternative splicing can provide a better understanding of the development of eukaryotes and the functions of different genes. Schistosoma japonicum is an infectious blood-dwelling trematode with a complex lifecycle that causes the tropical disease schistosomiasis. In this study, we analyzed the transcriptome of Schistosoma japonicum to discover alternative splicing events in this parasite, by applying RNA-seq to cDNA library of adults and schistosomula. Results were validated by RT-PCR and sequencing. We found 11,623 alternative splicing events among 7,099 protein encoding genes and average proportion of alternative splicing events per gene was 42.14%. We showed that exon skip is the most common type of alternative splicing events as found in high eukaryotes, whereas intron retention is the least common alternative splicing type. According to intron boundary analysis, the parasite possesses same intron boundaries as other organisms, namely the classic "GT-AG" rule. And in alternative spliced introns or exons, this rule is less strict. And we have attempted to detect alternative splicing events in genes encoding proteins with signal peptides and transmembrane helices, suggesting that alternative splicing could change subcellular locations of specific gene products. Our results indicate that alternative splicing is prevalent in this parasitic worm, and that the worm is close to its hosts. The revealed secretome involved in alternative splicing implies new perspective into understanding interaction between the parasite and its host.
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Affiliation(s)
- Xinye Wang
- Institute for Infectious Diseases and Vaccine Development, Tongji University School of Medicine, Shanghai, China
| | - Xindong Xu
- Institute for Infectious Diseases and Vaccine Development, Tongji University School of Medicine, Shanghai, China
| | - Xingyu Lu
- School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Yuanbin Zhang
- Institute for Infectious Diseases and Vaccine Development, Tongji University School of Medicine, Shanghai, China
| | - Weiqing Pan
- Institute for Infectious Diseases and Vaccine Development, Tongji University School of Medicine, Shanghai, China
- Department of Tropical Infectious Diseases, Second Military Medical University, Shanghai, China
- * E-mail:
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