1
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Gorkhali R, Tian L, Dong B, Bagchi P, Deng X, Pawar S, Duong D, Fang N, Seyfried N, Yang J. Extracellular calcium alters calcium-sensing receptor network integrating intracellular calcium-signaling and related key pathway. Sci Rep 2021; 11:20576. [PMID: 34663830 PMCID: PMC8523568 DOI: 10.1038/s41598-021-00067-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Accepted: 09/29/2021] [Indexed: 12/21/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) are a target for over 34% of current drugs. The calcium-sensing receptor (CaSR), a family C GPCR, regulates systemic calcium (Ca2+) homeostasis that is critical for many physiological, calciotropical, and noncalciotropical outcomes in multiple organs. However, the mechanisms by which extracellular Ca2+ (Ca2+ex) and the CaSR mediate networks of intracellular Ca2+-signaling and players involved throughout the life cycle of CaSR are largely unknown. Here we report the first CaSR protein–protein interactome with 94 novel putative and 8 previously published interactors using proteomics. Ca2+ex promotes enrichment of 66% of the identified CaSR interactors, pertaining to Ca2+ dynamics, endocytosis, degradation, trafficking, and primarily to protein processing in the endoplasmic reticulum (ER). These enhanced ER-related processes are governed by Ca2+ex-activated CaSR which directly modulates ER-Ca2+ (Ca2+ER), as monitored by a novel ER targeted Ca2+-sensor. Moreover, we validated the Ca2+ex dependent colocalizations and interactions of CaSR with ER-protein processing chaperone, 78-kDa glucose regulated protein (GRP78), and with trafficking-related protein. Live cell imaging results indicated that CaSR and vesicle-associated membrane protein-associated A (VAPA) are inter-dependent during Ca2+ex induced enhancement of near-cell membrane expression. This study significantly extends the repertoire of the CaSR interactome and reveals likely novel players and pathways of CaSR participating in Ca2+ER dynamics, agonist mediated ER-protein processing and surface expression.
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Affiliation(s)
- Rakshya Gorkhali
- Department of Chemistry, Center of Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, Atlanta, GA, 30303, USA
| | - Li Tian
- Department of Chemistry, Center of Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, Atlanta, GA, 30303, USA
| | - Bin Dong
- Department of Chemistry, Center of Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, Atlanta, GA, 30303, USA
| | - Pritha Bagchi
- Emory Integrated Proteomics Core, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Xiaonan Deng
- Department of Chemistry, Center of Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, Atlanta, GA, 30303, USA
| | - Shrikant Pawar
- Department of Biology, Center of Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, Atlanta, GA, 30303, USA
| | - Duc Duong
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Ning Fang
- Department of Chemistry, Center of Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, Atlanta, GA, 30303, USA
| | - Nicholas Seyfried
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Jenny Yang
- Department of Chemistry, Center of Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, Atlanta, GA, 30303, USA.
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2
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Cho CH, Hwang EM, Park JY. Emerging Roles of TWIK-1 Heterodimerization in the Brain. Int J Mol Sci 2017; 19:E51. [PMID: 29295556 PMCID: PMC5796001 DOI: 10.3390/ijms19010051] [Citation(s) in RCA: 5] [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: 11/28/2017] [Revised: 12/20/2017] [Accepted: 12/22/2017] [Indexed: 12/29/2022] Open
Abstract
Two-pore domain K⁺ (K2P) channels play essential roles in regulating resting membrane potential and cellular excitability. Although TWIK-1 (TWIK-tandem of pore domains in a weak inward rectifying K⁺ channel) was the first identified member of the K2P channel family, it is only in recent years that the physiological roles of TWIK-1 have been studied in depth. A series of reports suggest that TWIK-1 may underlie diverse functions, such as intrinsic excitability of neurons, astrocytic passive conductance, and astrocytic glutamate release, as a homodimer or heterodimer with other K2P isotypes. Here, we summarize expression patterns and newly identified functions of TWIK-1 in the brain.
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Affiliation(s)
- Chang-Hoon Cho
- School of Biosystem and Biomedical Science, College of Health Science, Korea University, Seoul 136-703, Korea.
| | - Eun Mi Hwang
- Korea Institute of Science and Technology (KIST), Center for Functional Connectomics, Seoul 02792, Korea.
- KHU-KIST Department of Converging Science and Technology, Kyung Hee University, Seoul 02447, Korea.
| | - Jae-Yong Park
- School of Biosystem and Biomedical Science, College of Health Science, Korea University, Seoul 136-703, Korea.
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3
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Rouwette T, Avenali L, Sondermann J, Narayanan P, Gomez-Varela D, Schmidt M. Modulation of nociceptive ion channels and receptors via protein-protein interactions: implications for pain relief. Channels (Austin) 2015; 9:175-85. [PMID: 26039491 DOI: 10.1080/19336950.2015.1051270] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In the last 2 decades biomedical research has provided great insights into the molecular signatures underlying painful conditions. However, chronic pain still imposes substantial challenges to researchers, clinicians and patients alike. Under pathological conditions, pain therapeutics often lack efficacy and exhibit only minimal safety profiles, which can be largely attributed to the targeting of molecules with key physiological functions throughout the body. In light of these difficulties, the identification of molecules and associated protein complexes specifically involved in chronic pain states is of paramount importance for designing selective interventions. Ion channels and receptors represent primary targets, as they critically shape nociceptive signaling from the periphery to the brain. Moreover, their function requires tight control, which is usually implemented by protein-protein interactions (PPIs). Indeed, manipulation of such PPIs entails the modulation of ion channel activity with widespread implications for influencing nociceptive signaling in a more specific way. In this review, we highlight recent advances in modulating ion channels and receptors via their PPI networks in the pursuit of relieving chronic pain. Moreover, we critically discuss the potential of targeting PPIs for developing novel pain therapies exhibiting higher efficacy and improved safety profiles.
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Affiliation(s)
- Tom Rouwette
- a Max Planck Institute for Experimental Medicine. Somatosensory Signaling Group ; Goettingen , Germany
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4
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Proft J, Weiss N. G protein regulation of neuronal calcium channels: back to the future. Mol Pharmacol 2014; 87:890-906. [PMID: 25549669 DOI: 10.1124/mol.114.096008] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 12/30/2014] [Indexed: 11/22/2022] Open
Abstract
Neuronal voltage-gated calcium channels have evolved as one of the most important players for calcium entry into presynaptic endings responsible for the release of neurotransmitters. In turn, and to fine-tune synaptic activity and neuronal communication, numerous neurotransmitters exert a potent negative feedback over the calcium signal provided by G protein-coupled receptors. This regulation pathway of physiologic importance is also extensively exploited for therapeutic purposes, for instance in the treatment of neuropathic pain by morphine and other μ-opioid receptor agonists. However, despite more than three decades of intensive research, important questions remain unsolved regarding the molecular and cellular mechanisms of direct G protein inhibition of voltage-gated calcium channels. In this study, we revisit this particular regulation and explore new considerations.
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Affiliation(s)
- Juliane Proft
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Norbert Weiss
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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5
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A disulphide-linked heterodimer of TWIK-1 and TREK-1 mediates passive conductance in astrocytes. Nat Commun 2014; 5:3227. [DOI: 10.1038/ncomms4227] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 01/09/2014] [Indexed: 01/22/2023] Open
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6
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Woo DH, Han KS, Shim JW, Yoon BE, Kim E, Bae JY, Oh SJ, Hwang EM, Marmorstein AD, Bae YC, Park JY, Lee CJ. TREK-1 and Best1 channels mediate fast and slow glutamate release in astrocytes upon GPCR activation. Cell 2012; 151:25-40. [PMID: 23021213 DOI: 10.1016/j.cell.2012.09.005] [Citation(s) in RCA: 254] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 06/18/2012] [Accepted: 09/05/2012] [Indexed: 11/28/2022]
Abstract
Astrocytes release glutamate upon activation of various GPCRs to exert important roles in synaptic functions. However, the molecular mechanism of release has been controversial. Here, we report two kinetically distinct modes of nonvesicular, channel-mediated glutamate release. The fast mode requires activation of G(αi), dissociation of G(βγ), and subsequent opening of glutamate-permeable, two-pore domain potassium channel TREK-1 through direct interaction between G(βγ) and N terminus of TREK-1. The slow mode is Ca(2+) dependent and requires G(αq) activation and opening of glutamate-permeable, Ca(2+)-activated anion channel Best1. Ultrastructural analyses demonstrate that TREK-1 is preferentially localized at cell body and processes, whereas Best1 is mostly found in microdomains of astrocytes near synapses. Diffusion modeling predicts that the fast mode can target neuronal mGluR with peak glutamate concentration of 100 μM, whereas slow mode targets neuronal NMDA receptors at around 1 μM. Our results reveal two distinct sources of astrocytic glutamate that can differentially influence neighboring neurons.
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Affiliation(s)
- Dong Ho Woo
- Center for Neural Science, Korea Institute of Science and Technology, Seoul, Republic of Korea
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7
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Zamponi GW, Currie KPM. Regulation of Ca(V)2 calcium channels by G protein coupled receptors. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1629-43. [PMID: 23063655 DOI: 10.1016/j.bbamem.2012.10.004] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 10/02/2012] [Accepted: 10/04/2012] [Indexed: 12/29/2022]
Abstract
Voltage gated calcium channels (Ca²⁺ channels) are key mediators of depolarization induced calcium influx into excitable cells, and thereby play pivotal roles in a wide array of physiological responses. This review focuses on the inhibition of Ca(V)2 (N- and P/Q-type) Ca²⁺-channels by G protein coupled receptors (GPCRs), which exerts important autocrine/paracrine control over synaptic transmission and neuroendocrine secretion. Voltage-dependent inhibition is the most widespread mechanism, and involves direct binding of the G protein βγ dimer (Gβγ) to the α1 subunit of Ca(V)2 channels. GPCRs can also recruit several other distinct mechanisms including phosphorylation, lipid signaling pathways, and channel trafficking that result in voltage-independent inhibition. Current knowledge of Gβγ-mediated inhibition is reviewed, including the molecular interactions involved, determinants of voltage-dependence, and crosstalk with other cell signaling pathways. A summary of recent developments in understanding the voltage-independent mechanisms prominent in sympathetic and sensory neurons is also included. This article is part of a Special Issue entitled: Calcium channels.
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Affiliation(s)
- Gerald W Zamponi
- Department of Physiology & Pharmacology, Hotchkiss Brain Institute, University of Calgary, Canada
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8
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Betke KM, Wells CA, Hamm HE. GPCR mediated regulation of synaptic transmission. Prog Neurobiol 2012; 96:304-21. [PMID: 22307060 DOI: 10.1016/j.pneurobio.2012.01.009] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 01/12/2012] [Accepted: 01/20/2012] [Indexed: 02/06/2023]
Abstract
Synaptic transmission is a finely regulated mechanism of neuronal communication. The release of neurotransmitter at the synapse is not only the reflection of membrane depolarization events, but rather, is the summation of interactions between ion channels, G protein coupled receptors, second messengers, and the exocytotic machinery itself which exposes the components within a synaptic vesicle to the synaptic cleft. The focus of this review is to explore the role of G protein signaling as it relates to neurotransmission, as well as to discuss the recently determined inhibitory mechanism of Gβγ dimers acting directly on the exocytotic machinery proteins to inhibit neurotransmitter release.
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Affiliation(s)
- Katherine M Betke
- Vanderbilt University Medical Center, 442 Robinson Research Building, 23rd Ave. South @ Pierce, Nashville, TN 37232-6600, USA.
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9
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Dingus J, Hildebrandt JD. Synthesis and assembly of G protein βγ dimers: comparison of in vitro and in vivo studies. Subcell Biochem 2012; 63:155-80. [PMID: 23161138 DOI: 10.1007/978-94-007-4765-4_9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The heterotrimeric GTP-binding proteins (G proteins) are the canonical cellular machinery used with the approximately 700 G protein-coupled receptors (GPCRs) in the human genome to transduce extracellular signals across the plasma membrane. The synthesis of the constituent G protein subunits, and their assembly into Gβγ dimers and G protein heterotrimers, determines the signaling repertoire for G-protein/GPCR signaling in cells. These synthesis/assembly -processes are intimately related to two other overlapping events in the intricate pathway leading to formation of G protein signaling complexes, posttranslational modification and intracellular trafficking of G proteins. The assembly of the Gβγ dimer is a complex process involving multiple accessory proteins and organelles. The mechanisms involved are becoming increasingly appreciated, but are still incompletely understood. In vitro and in vivo (cellular) studies provide different perspectives of these processes, and a comparison of them can provide insight into both our current level of understanding and directions to be taken in future investigations.
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Affiliation(s)
- Jane Dingus
- Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Charleston, SC, 29425, USA
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10
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Abstract
Voltage-gated Ca(2+) channels translate the electrical inputs of excitable cells into biochemical outputs by controlling influx of the ubiquitous second messenger Ca(2+) . As such the channels play pivotal roles in many cellular functions including the triggering of neurotransmitter and hormone release by CaV2.1 (P/Q-type) and CaV2.2 (N-type) channels. It is well established that G protein coupled receptors (GPCRs) orchestrate precise regulation neurotransmitter and hormone release through inhibition of CaV2 channels. Although the GPCRs recruit a number of different pathways, perhaps the most prominent, and certainly most studied among these is the so-called voltage-dependent inhibition mediated by direct binding of Gβγ to the α1 subunit of CaV2 channels. This article will review the basics of Ca(2+) -channels and G protein signaling, and the functional impact of this now classical inhibitory mechanism on channel function. It will also provide an update on more recent developments in the field, both related to functional effects and crosstalk with other signaling pathways, and advances made toward understanding the molecular interactions that underlie binding of Gβγ to the channel and the voltage-dependence that is a signature characteristic of this mechanism.
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Affiliation(s)
- Kevin P M Currie
- Department of Anesthesiology, Pharmacology and Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville, TN, USA.
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11
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Oh E, Maejima T, Liu C, Deneris E, Herlitze S. Substitution of 5-HT1A receptor signaling by a light-activated G protein-coupled receptor. J Biol Chem 2010; 285:30825-36. [PMID: 20643652 DOI: 10.1074/jbc.m110.147298] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Understanding serotonergic (5-HT) signaling is critical for understanding human physiology, behavior, and neuropsychiatric disease. 5-HT mediates its actions via ionotropic and metabotropic 5-HT receptors. The 5-HT(1A) receptor is a metabotropic G protein-coupled receptor linked to the G(i/o) signaling pathway and has been specifically implicated in the pathogenesis of depression and anxiety. To understand and precisely control 5-HT(1A) signaling, we created a light-activated G protein-coupled receptor that targets into 5-HT(1A) receptor domains and substitutes for endogenous 5-HT(1A) receptors. To induce 5-HT(1A)-like targeting, vertebrate rhodopsin was tagged with the C-terminal domain (CT) of 5-HT(1A) (Rh-CT(5-HT1A)). Rh-CT(5-HT1A) activates G protein-coupled inward rectifying K(+) channels in response to light and causes membrane hyperpolarization in hippocampal neurons, similar to the agonist-induced responses of the 5-HT(1A) receptor. The intracellular distribution of Rh-CT(5-HT1A) resembles that of the 5-HT(1A) receptor; Rh-CT(5-HT1A) localizes to somatodendritic sites and is efficiently trafficked to distal dendritic processes. Additionally, neuronal expression of Rh-CT(5-HT1A), but not Rh, decreases 5-HT(1A) agonist sensitivity, suggesting that Rh-CT(5-HT1A) and 5-HT(1A) receptors compete to interact with the same trafficking machinery. Finally, Rh-CT(5-HT1A) is able to rescue 5-HT(1A) signaling of 5-HT(1A) KO mice in cultured neurons and in slices of the dorsal raphe showing that Rh-CT(5-HT1A) is able to functionally compensate for native 5-HT(1A). Thus, as an optogenetic tool, Rh-CT(5-HT1A) has the potential to directly correlate in vivo 5-HT(1A) signaling with 5-HT neuron activity and behavior in both normal animals and animal models of neuropsychiatric disease.
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Affiliation(s)
- Eugene Oh
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
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12
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Abstract
Advances in optics, genetics, and chemistry have enabled the investigation of brain function at all levels, from intracellular signals to single synapses, whole cells, circuits, and behavior. Until recent years, these research tools have been utilized in an observational capacity: imaging neural activity with fluorescent reporters, for example, or correlating aberrant neural activity with loss-of-function and gain-of-function pharmacological or genetic manipulations. However, optics, genetics, and chemistry have now combined to yield a new strategy: using light to drive and halt neuronal activity with molecular specificity and millisecond precision. Photostimulation of neurons is noninvasive, has unmatched spatial and temporal resolution, and can be targeted to specific classes of neurons. The optical methods developed to date encompass a broad array of strategies, including photorelease of caged neurotransmitters, engineered light-gated receptors and channels, and naturally light-sensitive ion channels and pumps. In this review, we describe photostimulation methods, their applications, and opportunities for further advancement.
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Affiliation(s)
- Stephanie Szobota
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
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13
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Targeting Bcl-2-IP3 receptor interaction to reverse Bcl-2's inhibition of apoptotic calcium signals. Mol Cell 2008; 31:255-65. [PMID: 18657507 DOI: 10.1016/j.molcel.2008.06.014] [Citation(s) in RCA: 198] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Revised: 02/26/2008] [Accepted: 06/01/2008] [Indexed: 12/12/2022]
Abstract
The antiapoptotic protein Bcl-2 inhibits Ca2+ release from the endoplasmic reticulum (ER). One proposed mechanism involves an interaction of Bcl-2 with the inositol 1,4,5-trisphosphate receptor (IP3R) Ca2+ channel localized with Bcl-2 on the ER. Here we document Bcl-2-IP3R interaction within cells by FRET and identify a Bcl-2 interacting region in the regulatory and coupling domain of the IP3R. A peptide based on this IP3R sequence displaced Bcl-2 from the IP3R and reversed Bcl-2-mediated inhibition of IP3R channel activity in vitro, IP3-induced ER Ca2+ release in permeabilized cells, and cell-permeable IP3 ester-induced Ca2+ elevation in intact cells. This peptide also reversed Bcl-2's inhibition of T cell receptor-induced Ca2+ elevation and apoptosis. Thus, the interaction of Bcl-2 with IP3Rs contributes to the regulation of proapoptotic Ca2+ signals by Bcl-2, suggesting the Bcl-2-IP3R interaction as a potential therapeutic target in diseases associated with Bcl-2's inhibition of cell death.
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14
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Xie M, Li X, Han J, Vogt DL, Wittemann S, Mark MD, Herlitze S. Facilitation versus depression in cultured hippocampal neurons determined by targeting of Ca2+ channel Cavbeta4 versus Cavbeta2 subunits to synaptic terminals. ACTA ACUST UNITED AC 2007; 178:489-502. [PMID: 17664337 PMCID: PMC2064847 DOI: 10.1083/jcb.200702072] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca2+ channel β subunits determine the transport and physiological properties of high voltage–activated Ca2+ channel complexes. Our analysis of the distribution of the Cavβ subunit family members in hippocampal neurons correlates their synaptic distribution with their involvement in transmitter release. We find that exogenously expressed Cavβ4b and Cavβ2a subunits distribute in clusters and localize to synapses, whereas Cavβ1b and Cavβ3 are homogenously distributed. According to their localization, Cavβ2a and Cavβ4b subunits modulate the synaptic plasticity of autaptic hippocampal neurons (i.e., Cavβ2a induces depression, whereas Cavβ4b induces paired-pulse facilitation [PPF] followed by synaptic depression during longer stimuli trains). The induction of PPF by Cavβ4b correlates with a reduction in the release probability and cooperativity of the transmitter release. These results suggest that Cavβ subunits determine the gating properties of the presynaptic Ca2+ channels within the presynaptic terminal in a subunit-specific manner and may be involved in organization of the Ca2+ channel relative to the release machinery.
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Affiliation(s)
- Mian Xie
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA
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15
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DePuy SD, Yao J, Hu C, McIntire W, Bidaud I, Lory P, Rastinejad F, Gonzalez C, Garrison JC, Barrett PQ. The molecular basis for T-type Ca2+ channel inhibition by G protein beta2gamma2 subunits. Proc Natl Acad Sci U S A 2006; 103:14590-5. [PMID: 16973746 PMCID: PMC1600004 DOI: 10.1073/pnas.0603945103] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Gbetagamma, a ubiquitous second messenger, relays external signals from G protein-coupled receptors to networks of intracellular effectors, including voltage-dependent calcium channels. Unlike high-voltage-activated Ca(2+) channels, the inhibition of low-voltage-activated Ca(2+) channels is subtype-dependent and mediated selectively by Gbeta(2)-containing dimers. Yet, the molecular basis for this exquisite selectivity remains unknown. Here, we used pure recombinant Gbetagamma subunits to establish that the Gbeta(2)gamma(2) dimer can selectively reconstitute the inhibition of alpha(1H) channels in isolated membrane patches. This inhibition is the result of a reduction in channel open probability that is not accompanied by a change in channel expression or an alteration in active-channel gating. By exchanging residues between the active Gbeta(2) subunit and the inactive Gbeta(1) subunit, we identified a cluster of amino acids that functionally distinguish Gbeta(2) from other Gbeta subunits. These amino acids on the beta-torus identify a region that is distinct from those regions that contact the Galpha subunit or other effectors.
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Affiliation(s)
| | | | | | | | - Isabelle Bidaud
- Département de Physiologie, Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5203, Institut National de la Santé et de la Recherche Médicale U661, Université Montpellier I et II, 34095 Montpellier, France
| | - Philippe Lory
- Département de Physiologie, Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5203, Institut National de la Santé et de la Recherche Médicale U661, Université Montpellier I et II, 34095 Montpellier, France
| | | | - Carlos Gonzalez
- Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908; and
| | | | - Paula Q. Barrett
- Departments of *Pharmacology and
- To whom correspondence should be addressed at:
Department of Pharmacology, University of Virginia School of Medicine, 1300 Jefferson Park Avenue, Charlottesville, VA 22908. E-mail:
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16
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Weiss N, Arnoult C, Feltz A, De Waard M. Contribution of the kinetics of G protein dissociation to the characteristic modifications of N-type calcium channel activity. Neurosci Res 2006; 56:332-43. [PMID: 16973229 DOI: 10.1016/j.neures.2006.08.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2006] [Revised: 07/26/2006] [Accepted: 08/02/2006] [Indexed: 11/23/2022]
Abstract
Direct G protein inhibition of N-type calcium channels is recognized by characteristic biophysical modifications. In this study, we quantify and simulate the importance of G protein dissociation on the phenotype of G protein-regulated whole-cell currents. Based on the observation that the voltage-dependence of the time constant of recovery from G protein inhibition is correlated with the voltage-dependence of channel opening, we depict all G protein effects by a simple kinetic scheme. All landmark modifications in calcium currents, except inhibition, can be successfully described using three simple biophysical parameters (extent of block, extent of recovery, and time constant of recovery). Modifications of these parameters by auxiliary beta subunits are at the origin of differences in N-type channel regulation by G proteins. The simulation data illustrate that channel reluctance can occur as the result of an experimental bias linked to the variable extent of G protein dissociation when peak currents are measured at various membrane potentials. To produce alterations in channel kinetics, the two most important parameters are the extents of initial block and recovery. These data emphasize the contribution of the degree and kinetics of G protein dissociation in the modification of N-type currents.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Calcium Channels, N-Type/physiology
- Dose-Response Relationship, Drug
- Dose-Response Relationship, Radiation
- Electric Stimulation/methods
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- GTP-Binding Protein beta Subunits/genetics
- GTP-Binding Protein beta Subunits/metabolism
- GTP-Binding Proteins/antagonists & inhibitors
- GTP-Binding Proteins/chemistry
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Membrane Potentials/radiation effects
- Microinjections/methods
- Models, Neurological
- Oocytes
- Patch-Clamp Techniques/methods
- Rabbits
- Rats
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Xenopus
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Affiliation(s)
- Norbert Weiss
- Inserm U607, Laboratoire Canaux Calciques, Fonctions et Pathologies, 17 Rue des Martyrs, Bâtiment C3, 38054 Grenoble Cedex 09, France
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17
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Chen R, Chang PA, Long DX, Liu CY, Yang L, Wu YJ. G protein beta2 subunit interacts directly with neuropathy target esterase and regulates its activity. Int J Biochem Cell Biol 2006; 39:124-32. [PMID: 16978909 DOI: 10.1016/j.biocel.2006.08.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 08/09/2006] [Accepted: 08/10/2006] [Indexed: 11/26/2022]
Abstract
Neuropathy target esterase (NTE) was identified as the primary target of organophosphate compounds that cause a delayed neuropathy with degeneration of nerve axons. NTE is a novel phospholipase B anchored to the cytoplasmic face of endoplasmic reticulum and essential for embryonic and nervous development. However, little is known about the regulation of NTE. A human fetal brain cDNA library was screened for proteins that interact with NTE, Gbeta2 and Gbeta2-like I subunits were found to be able to bind the C-terminal of NTE in yeast. The interaction of Gbeta2 and NTE was confirmed by in vivo co-immunoprecipitation analysis in COS7 cells. Furthermore, depletion of Gbeta2 by RNA interference down regulated the activity of NTE but not its expression level. In addition, the activity of NTE was down regulated by the G protein signal pathway influencing factor, pertussis toxin, treatment in vivo. These findings suggest that Gbeta2 may play a significant role in maintaining the activity of NTE.
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Affiliation(s)
- Rui Chen
- Laboratory of Molecular Toxicology, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, PR China
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Gros E, Deshayes S, Morris MC, Aldrian-Herrada G, Depollier J, Heitz F, Divita G. A non-covalent peptide-based strategy for protein and peptide nucleic acid transduction. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:384-93. [PMID: 16545342 DOI: 10.1016/j.bbamem.2006.02.006] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Revised: 01/20/2006] [Accepted: 02/07/2006] [Indexed: 01/20/2023]
Abstract
The development of therapeutic peptides and proteins is limited by the poor permeability and the selectivity of the cell membrane. The discovery of protein transduction domains has given a new hope for administration of large proteins and peptides in vivo. We have developed a non-covalent strategy for protein transduction based on an amphipathic peptide, Pep-1, that consists of a hydrophobic domain and a hydrophilic lysine-rich domain. Pep-1 efficiently delivers a variety of fully biologically active peptides and proteins into cells, without the need for prior chemical cross-linking or chemical modifications. The mechanism through which Pep-1 delivers active macromolecules does not involve the endosomal pathway and the dissociation of the Pep-1/macromolecule particle occurs immediately after it crosses the cell membrane. Pep-1 has been successfully applied to the screening of therapeutic peptides in vivo and presents several advantages: stability in physiological buffer, lack of toxicity and of sensitivity to serum. In conclusion, Pep-1 technology could contribute significantly to the development of fundamental and therapeutic applications and be an alternative to covalent protein transduction domain-based technologies.
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Affiliation(s)
- Edwige Gros
- Centre de Recherches de Biochimie Macromoléculaire, CRBM-CNRS, Department of Molecular Biophysics and Therapeutic, 1919 Route de Mende, 34293 Montpellier, France
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19
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Li X, Gutierrez DV, Hanson MG, Han J, Mark MD, Chiel H, Hegemann P, Landmesser LT, Herlitze S. Fast noninvasive activation and inhibition of neural and network activity by vertebrate rhodopsin and green algae channelrhodopsin. Proc Natl Acad Sci U S A 2005; 102:17816-21. [PMID: 16306259 PMCID: PMC1292990 DOI: 10.1073/pnas.0509030102] [Citation(s) in RCA: 386] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Techniques for fast noninvasive control of neuronal excitability will be of major importance for analyzing and understanding neuronal networks and animal behavior. To develop these tools we demonstrated that two light-activated signaling proteins, vertebrate rat rhodopsin 4 (RO4) and the green algae channelrhodospin 2 (ChR2), could be used to control neuronal excitability and modulate synaptic transmission. Vertebrate rhodopsin couples to the Gi/o, pertussis toxin-sensitive pathway to allow modulation of G protein-gated inward rectifying potassium channels and voltage-gated Ca2+ channels. Light-mediated activation of RO4 in cultured hippocampal neurons reduces neuronal firing within ms by hyperpolarization of the somato-dendritic membrane and when activated at presynaptic sites modulates synaptic transmission and paired-pulse facilitation. In contrast, somato-dendritic activation of ChR2 depolarizes neurons sufficiently to induce immediate action potentials, which precisely follow the ChR2 activation up to light stimulation frequencies of 20 Hz. To demonstrate that these constructs are useful for regulating network behavior in intact organisms, embryonic chick spinal cords were electroporated with either construct, allowing the frequency of episodes of spontaneous bursting activity, known to be important for motor circuit formation, to be precisely controlled. Thus light-activated vertebrate RO4 and green algae ChR2 allow the antagonistic control of neuronal function within ms to s in a precise, reversible, and noninvasive manner in cultured neurons and intact vertebrate spinal cords.
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Affiliation(s)
- Xiang Li
- Department of Neurosciences, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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De Waard M, Hering J, Weiss N, Feltz A. How do G proteins directly control neuronal Ca2+ channel function? Trends Pharmacol Sci 2005; 26:427-36. [PMID: 16009433 DOI: 10.1016/j.tips.2005.06.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Revised: 05/03/2005] [Accepted: 06/22/2005] [Indexed: 10/25/2022]
Abstract
Ca2+ entry into neuronal cells is modulated by the activation of numerous G-protein-coupled receptors (GPCRs). Much effort has been invested in studying direct G-protein-mediated inhibition of voltage-dependent CaV2 Ca2+ channels. This inhibition occurs through a series of convergent modifications in the biophysical properties of the channels. An integrated view of the structural organization of the Gbetagamma-dimer binding-site pocket within the channel is emerging. In this review, we discuss how variable geometry of the Gbetagamma binding pocket can yield distinct sets of channel inhibition. In addition, we propose specific mechanisms for the regulation of the channel by G proteins that take into account the regulatory input of each Gbetagamma binding element.
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Affiliation(s)
- Michel De Waard
- Laboratoire Canaux Calciques, Fonctions et Pathologies, Inserm U607, CEA, DRDC, 17 rue des Martyrs, 38054 Grenoble Cedex 09, France.
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