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Amos C, Kiessling V, Kreutzberger AJB, Schenk NA, Mohan R, Nyenhuis S, Doyle CA, Wang HY, Levental K, Levental I, Anantharam A, Tamm LK. Membrane lipids couple synaptotagmin to SNARE-mediated granule fusion in insulin-secreting cells. Mol Biol Cell 2024; 35:ar12. [PMID: 38117594 PMCID: PMC10916878 DOI: 10.1091/mbc.e23-06-0225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 12/04/2023] [Accepted: 12/14/2023] [Indexed: 12/22/2023] Open
Abstract
Insulin secretion depends on the Ca2+-regulated fusion of granules with the plasma membrane. A recent model of Ca2+-triggered exocytosis in secretory cells proposes that lipids in the plasma membrane couple the calcium sensor Syt1 to the membrane fusion machinery (Kiessling et al., 2018). Specifically, Ca2+-mediated binding of Syt1's C2 domains to the cell membrane shifts the membrane-anchored SNARE syntaxin-1a to a more fusogenic conformation, straightening its juxtamembrane linker. To test this model in live cells and extend it to insulin secretion, we enriched INS1 cells with a panel of lipids with different acyl chain compositions. Fluorescence lifetime measurements demonstrate that cells with more disordered membranes show an increase in fusion efficiency, and vice versa. Experiments with granules purified from INS1 cells and recombinant SNARE proteins reconstituted in supported membranes confirmed that lipid acyl chain composition determines SNARE conformation and that lipid disordering correlates with increased fusion. Addition of Syt1's C2AB domains significantly decreased lipid order in target membranes and increased SNARE-mediated fusion probability. Strikingly, Syt's action on both fusion and lipid order could be partially bypassed by artificially increasing unsaturated phosphatidylserines in the target membrane. Thus, plasma membrane lipids actively participate in coupling Ca2+/synaptotagmin-sensing to the SNARE fusion machinery in cells.
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Affiliation(s)
- Chase Amos
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Alex J. B. Kreutzberger
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Noah A. Schenk
- Department of Neurosciences, University of Toledo, Toledo, OH 43614
| | - Ramkumar Mohan
- Department of Neurosciences, University of Toledo, Toledo, OH 43614
| | - Sarah Nyenhuis
- Department of Chemistry, University of Virginia, Charlottesville, VA, 22904
| | - Catherine A. Doyle
- Department of Pharmacology, University of Virginia Health System, Charlottesville, VA 22908
| | - Hong-Yin Wang
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Kandice Levental
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Ilya Levental
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Arun Anantharam
- Department of Neurosciences, University of Toledo, Toledo, OH 43614
| | - Lukas K. Tamm
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
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Shin SM, Lauzadis J, Itson-Zoske B, Cai Y, Fan F, Natarajan GK, Kwok WM, Puopolo M, Hogan QH, Yu H. Targeting intrinsically disordered regions facilitates discovery of calcium channels 3.2 inhibitory peptides for adeno-associated virus-mediated peripheral analgesia. Pain 2022; 163:2466-2484. [PMID: 35420557 PMCID: PMC9562599 DOI: 10.1097/j.pain.0000000000002650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 03/19/2022] [Accepted: 03/23/2022] [Indexed: 11/27/2022]
Abstract
ABSTRACT Ample data support a prominent role of peripheral T-type calcium channels 3.2 (Ca V 3.2) in generating pain states. Development of primary sensory neuron-specific inhibitors of Ca V 3.2 channels is an opportunity for achieving effective analgesic therapeutics, but success has been elusive. Small peptides, especially those derived from natural proteins as inhibitory peptide aptamers (iPAs), can produce highly effective and selective blockade of specific nociceptive molecular pathways to reduce pain with minimal off-target effects. In this study, we report the engineering of the potent and selective iPAs of Ca V 3.2 from the intrinsically disordered regions (IDRs) of Ca V 3.2 intracellular segments. Using established prediction algorithms, we localized the IDRs in Ca V 3.2 protein and identified several Ca V 3.2iPA candidates that significantly reduced Ca V 3.2 current in HEK293 cells stably expressing human wide-type Ca V 3.2. Two prototype Ca V 3.2iPAs (iPA1 and iPA2) derived from the IDRs of Ca V 3.2 intracellular loops 2 and 3, respectively, were expressed selectively in the primary sensory neurons of dorsal root ganglia in vivo using recombinant adeno-associated virus (AAV), which produced sustained inhibition of calcium current conducted by Ca V 3.2/T-type channels and significantly attenuated both evoked and spontaneous pain behavior in rats with neuropathic pain after tibial nerve injury. Recordings from dissociated sensory neurons showed that AAV-mediated Ca V 3.2iPA expression suppressed neuronal excitability, suggesting that Ca V 3.2iPA treatment attenuated pain by reversal of injury-induced neuronal hypersensitivity. Collectively, our results indicate that Ca V 3.2iPAs are promising analgesic leads that, combined with AAV-mediated delivery in anatomically targeted sensory ganglia, have the potential to be a selective peripheral Ca V 3.2-targeting strategy for clinical treatment of pain.
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Affiliation(s)
- Seung Min Shin
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Justas Lauzadis
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY, United States
| | - Brandon Itson-Zoske
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Yongsong Cai
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States
- Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, People's Republic of China
| | - Fan Fan
- Department of Pharmacology and Toxicology, The University of Mississippi Medical Center, Jackson, MS, United States
| | - Gayathri K. Natarajan
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Wai-Meng Kwok
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Michelino Puopolo
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY, United States
| | - Quinn H. Hogan
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Hongwei Yu
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States
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Cherkashin AP, Rogachevskaja OA, Kabanova NV, Kotova PD, Bystrova MF, Kolesnikov SS. Taste Cells of the Type III Employ CASR to Maintain Steady Serotonin Exocytosis at Variable Ca 2+ in the Extracellular Medium. Cells 2022; 11:cells11081369. [PMID: 35456048 PMCID: PMC9030112 DOI: 10.3390/cells11081369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 04/07/2022] [Accepted: 04/11/2022] [Indexed: 12/17/2022] Open
Abstract
Type III taste cells are the only taste bud cells which express voltage-gated (VG) Ca2+ channels and employ Ca2+-dependent exocytosis to release neurotransmitters, particularly serotonin. The taste bud is a tightly packed cell population, wherein extracellular Ca2+ is expected to fluctuate markedly due to the electrical activity of taste cells. It is currently unclear whether the Ca2+ entry-driven synapse in type III cells could be reliable enough at unsteady extracellular Ca2. Here we assayed depolarization-induced Ca2+ signals and associated serotonin release in isolated type III cells at varied extracellular Ca2+. It turned out that the same depolarizing stimulus elicited invariant Ca2+ signals in type III cells irrespective of bath Ca2+ varied within 0.5–5 mM. The serotonin release from type III cells was assayed with the biosensor approach by using HEK-293 cells co-expressing the recombinant 5-HT4 receptor and genetically encoded cAMP sensor Pink Flamindo. Consistently with the weak Ca2+ dependence of intracellular Ca2+ transients produced by VG Ca2+ entry, depolarization-triggered serotonin secretion varied negligibly with bath Ca2+. The evidence implicated the extracellular Ca2+-sensing receptor in mediating the negative feedback mechanism that regulates VG Ca2+ entry and levels off serotonin release in type III cells at deviating Ca2+ in the extracellular medium.
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Bowman CE, Selen Alpergin ES, Ellis JM, Wolfgang MJ. Loss of ACOT7 potentiates seizures and metabolic dysfunction. Am J Physiol Endocrinol Metab 2019; 317:E941-E951. [PMID: 31039008 PMCID: PMC6879868 DOI: 10.1152/ajpendo.00537.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 04/24/2019] [Accepted: 04/24/2019] [Indexed: 01/02/2023]
Abstract
Neurons uniquely antagonize fatty acid utilization by hydrolyzing the activated form of fatty acids, long chain acyl-CoAs, via the enzyme acyl-CoA thioesterase 7, Acot7. The loss of Acot7 results in increased fatty acid utilization in neurons and exaggerated stimulus-evoked behavior such as an increased startle response. To understand the contribution of Acot7 to seizure susceptibility, we generated Acot7 knockout (KO) mice and assayed their response to kainate-induced seizures. Acot7 KO mice exhibited potentiated behavioral and molecular indices of seizure severity following kainic acid administration, suggesting that fatty acid metabolism in neurons can be a critical regulator of neuronal activity. These data are consistent with the presentation of seizures in a human with genomic deletion of ACOT7 demonstrating the conservation of function across species. To further understand the metabolic complications arising from a deletion in Acot7, we subjected Acot7 KO mice to a high-fat diet. While the loss of Acot7 did not result in metabolic complications following a normal chow diet, a high-fat diet induced greater body weight gain, adiposity, and glucose intolerance in Acot7 KO mice. These data demonstrate that Acot7, a fatty acid metabolic enzyme highly enriched in neurons, regulates both brain-specific metabolic processes related to seizure susceptibility and the whole body response to dietary lipid.
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Affiliation(s)
- Caitlyn E Bowman
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ebru S Selen Alpergin
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jessica M Ellis
- Department of Physiology, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina
| | - Michael J Wolfgang
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland
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5
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Bondarenko O, Corzo G, Santana FL, Río‐Portilla F, Darszon A, López‐González I. Nonenzymatically oxidized arachidonic acid regulates T‐type Ca
2+
currents in mouse spermatogenic cells. FEBS Lett 2019; 593:1735-1750. [DOI: 10.1002/1873-3468.13448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 05/14/2019] [Accepted: 05/16/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Olga Bondarenko
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología Universidad Nacional Autónoma de México México México
| | - Gerardo Corzo
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología Universidad Nacional Autónoma de México México México
| | - Félix L. Santana
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología Universidad Nacional Autónoma de México México México
| | - Federico Río‐Portilla
- Departamento de Biomacromoléculas. Instituto de Química Universidad Nacional Autónoma de México México México
| | - Alberto Darszon
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología Universidad Nacional Autónoma de México México México
| | - Ignacio López‐González
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología Universidad Nacional Autónoma de México México México
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Westman J, Grinstein S, Maxson ME. Revisiting the role of calcium in phagosome formation and maturation. J Leukoc Biol 2019; 106:837-851. [DOI: 10.1002/jlb.mr1118-444r] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 04/24/2019] [Accepted: 04/25/2019] [Indexed: 12/19/2022] Open
Affiliation(s)
- Johannes Westman
- Program in Cell BiologyHospital for Sick Children Toronto Ontario Canada
| | - Sergio Grinstein
- Program in Cell BiologyHospital for Sick Children Toronto Ontario Canada
- Department of BiochemistryUniversity of Toronto Toronto Ontario Canada
- Keenan Research Centre of the Li Ka Shing Knowledge InstituteSt. Michael's Hospital Toronto Ontario Canada
| | - Michelle E. Maxson
- Program in Cell BiologyHospital for Sick Children Toronto Ontario Canada
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Liu L, Bonventre JV, Rittenhouse AR. cPLA2α-/- sympathetic neurons exhibit increased membrane excitability and loss of N-Type Ca2+ current inhibition by M1 muscarinic receptor signaling. PLoS One 2018; 13:e0201322. [PMID: 30557348 PMCID: PMC6296557 DOI: 10.1371/journal.pone.0201322] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 07/11/2018] [Indexed: 11/18/2022] Open
Abstract
Group IVa cytosolic phospholipase A2 (cPLA2α) mediates GPCR-stimulated arachidonic acid (AA) release from phosphatidylinositol 4,5-bisphosphate (PIP2) located in plasma membranes. We previously found in superior cervical ganglion (SCG) neurons that PLA2 activity is required for voltage-independent N-type Ca2+ (N-) current inhibition by M1 muscarinic receptors (M1Rs). These findings are at odds with an alternative model, previously observed for M-current inhibition, where PIP2 dissociation from channels and subsequent metabolism by phospholipase C suffices for current inhibition. To resolve cPLA2α’s importance, we have investigated its role in mediating voltage-independent N-current inhibition (~40%) that follows application of the muscarinic agonist oxotremorine-M (Oxo-M). Preincubation with different cPLA2α antagonists or dialyzing cPLA2α antibodies into cells minimized N-current inhibition by Oxo-M, whereas antibodies to Ca2+-independent PLA2 had no effect. Taking a genetic approach, we found that SCG neurons from cPLA2α-/- mice exhibited little N-current inhibition by Oxo-M, confirming a role for cPLA2α. In contrast, cPLA2α antibodies or the absence of cPLA2α had no effect on voltage-dependent N-current inhibition by M2/M4Rs or on M-current inhibition by M1Rs. These findings document divergent M1R signaling mediating M-current and voltage-independent N-current inhibition. Moreover, these differences suggest that cPLA2α acts locally to metabolize PIP2 intimately associated with N- but not M-channels. To determine cPLA2α’s functional importance more globally, we examined action potential firing of cPLA2α+/+ and cPLA2α-/- SCG neurons, and found decreased latency to first firing and interspike interval resulting in a doubling of firing frequency in cPLA2α-/- neurons. These unanticipated findings identify cPLA2α as a tonic regulator of neuronal membrane excitability.
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Affiliation(s)
- Liwang Liu
- Program in Neuroscience, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Department of Physiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Joseph V. Bonventre
- Harvard Institute of Medicine, Harvard Medical School & Brigham and Women's Hospital, Boston, Massachusetts, United States of America
| | - Ann R. Rittenhouse
- Program in Neuroscience, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Department of Physiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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8
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Liu Y, Iwano T, Ma F, Wang P, Wang Y, Zheng M, Liu G, Ono K. Short- and long-term roles of phosphatidylinositol 4,5-bisphosphate PIP 2 on Cav3.1- and Cav3.2-T-type calcium channel current. ACTA ACUST UNITED AC 2018; 26:31-38. [PMID: 30528337 DOI: 10.1016/j.pathophys.2018.12.001] [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: 08/01/2018] [Revised: 11/30/2018] [Accepted: 12/01/2018] [Indexed: 11/24/2022]
Abstract
T-type calcium (Ca2+) channels play important physiological functions in excitable cells including cardiomyocyte. Phosphatidylinositol-4,5-bisphosphate (PIP2) has recently been reported to modulate various ion channels' function. However the actions of PIP2 on the T-type Ca2+ channel remain unclear. To elucidate possible effects of PIP2 on the T-type Ca2+ channel, we applied patch clamp method to investigate recombinant CaV3.1- and CaV3.2-T-type Ca2+ channels expressed in mammalian cell lines with PIP2 in acute- and long-term potentiation. Short- and long-term potentiation of PIP2 shifted the activation and the steady-state inactivation curve toward the hyperpolarization direction of CaV3.1-ICa.T without affecting the maximum inward current density. Short- and long-term potentiation of PIP2 also shifted the activation curve toward the hyperpolarization direction of CaV3.2-ICa.T without affecting the maximum inward current density. Conversely, long-term but not short-term potentiation of PIP2 shifted the steady-state inactivation curve toward the hyperpolarization direction of CaV3.2-ICa.T. Long-term but not short-term potentiation of PIP2 blunted the voltage-dependency of current decay CaV3.1-ICa.T. PIP2 modulates CaV3.1- and CaV3.2-ICa.T not by their current density but by their channel gating properties possibly through its membrane-delimited actions.
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Affiliation(s)
- Yangong Liu
- Department of Cardiology, The First Hospital of Hebei Medical University, 89 Donggang Road, Shijiazhuang, Hebei Province, 050031, People's Republic of China; Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Tomohiro Iwano
- Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Fangfang Ma
- Department of Cardiology, The First Hospital of Hebei Medical University, 89 Donggang Road, Shijiazhuang, Hebei Province, 050031, People's Republic of China; Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Pu Wang
- Department of Cardiology, The First Hospital of Hebei Medical University, 89 Donggang Road, Shijiazhuang, Hebei Province, 050031, People's Republic of China; Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Yan Wang
- Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Mingqi Zheng
- Department of Cardiology, The First Hospital of Hebei Medical University, 89 Donggang Road, Shijiazhuang, Hebei Province, 050031, People's Republic of China
| | - Gang Liu
- Department of Cardiology, The First Hospital of Hebei Medical University, 89 Donggang Road, Shijiazhuang, Hebei Province, 050031, People's Republic of China
| | - Katsushige Ono
- Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan.
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A Closely Associated Phospholipase C Regulates Cation Channel Function through Phosphoinositide Hydrolysis. J Neurosci 2018; 38:7622-7634. [PMID: 30037836 DOI: 10.1523/jneurosci.0586-18.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/28/2018] [Accepted: 07/17/2018] [Indexed: 11/21/2022] Open
Abstract
In the hemaphroditic sea snail, Aplysia californica, reproduction is initiated when the bag cell neurons secrete egg-laying hormone during a protracted afterdischarge. A source of depolarization for the afterdischarge is a voltage-gated, nonselective cation channel, similar to transient receptor potential (TRP) channels. Once the afterdischarge is triggered, phospholipase C (PLC) is activated to hydrolyze phosphatidylinositol-4,5-bisphosphate (PIP2) into diacylglycerol (DAG) and inositol trisphosphate (IP3). We previously reported that a DAG analog, 1-oleoyl-2-acetyl-sn-glycerol (OAG), activates a prominent, inward whole-cell cationic current that is enhanced by IP3 To examine the underlying mechanism, we investigated the effect of exogenous OAG and IP3, as well as PLC activation, on cation channel activity and voltage dependence in excised, inside-out patches from cultured bag cell neurons. OAG transiently elevated channel open probability (PO) when applied to excised patches; however, coapplication of IP3 prolonged the OAG-induced response. In patches exposed to OAG and IP3, channel voltage dependence was left-shifted; this was also observed with OAG, but not to the same extent. Introducing the PLC activator, m-3M3FBS, to patches increased channel PO, suggesting PLC may be physically linked to the channels. Accordingly, blocking PLC with U-73122 ablated the m-3M3FBS-induced elevation in PO Treatment with m-3M3FBS left-shifted cation channel voltage dependence to a greater extent than exogenous OAG and IP3 Finally, OAG and IP3 potentiated the stimulatory effect of PKC, which is also associated with the channel. Thus, the PLC-PKC signaling system is physically localized such that PIP2 breakdown products liberated during the afterdischarge modulate the cation channel and temporally influence neuronal activity.SIGNIFICANCE STATEMENT Using excised patches from Aplysia bag cell neurons, we present the first evidence of a nonselective cation channel physically associating with phospholipase C (PLC) at the single-channel level. PLC-mediated breakdown of phospholipids generates diacylglycerol and inositol trisphosphate, which activate the cation channel. This is mimicked by exogenous lipids; furthermore, these second messengers left-shift channel voltage dependence and enhance the response of the channel to protein kinase C. PLC-mediated lipid signaling controls single-channel currents to ensure depolarization is maintained for an extended period of firing, termed the afterdischarge, when the bag cell neurons secrete egg-laying hormone to trigger reproduction.
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10
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Brown DA. Regulation of neural ion channels by muscarinic receptors. Neuropharmacology 2017; 136:383-400. [PMID: 29154951 DOI: 10.1016/j.neuropharm.2017.11.024] [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: 11/08/2016] [Revised: 10/26/2017] [Accepted: 11/13/2017] [Indexed: 12/20/2022]
Abstract
The excitable behaviour of neurons is determined by the activity of their endogenous membrane ion channels. Since muscarinic receptors are not themselves ion channels, the acute effects of muscarinic receptor stimulation on neuronal function are governed by the effects of the receptors on these endogenous neuronal ion channels. This review considers some principles and factors determining the interaction between subtypes and classes of muscarinic receptors with neuronal ion channels, and summarizes the effects of muscarinic receptor stimulation on a number of different channels, the mechanisms of receptor - channel transduction and their direct consequences for neuronal activity. Ion channels considered include potassium channels (voltage-gated, inward rectifier and calcium activated), voltage-gated calcium channels, cation channels and chloride channels. This article is part of the Special Issue entitled 'Neuropharmacology on Muscarinic Receptors'.
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Affiliation(s)
- David A Brown
- Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
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11
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Park CG, Park Y, Suh BC. The HOOK region of voltage-gated Ca2+ channel β subunits senses and transmits PIP2 signals to the gate. J Gen Physiol 2017; 149:261-276. [PMID: 28087621 PMCID: PMC5299622 DOI: 10.1085/jgp.201611677] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 12/12/2016] [Accepted: 12/22/2016] [Indexed: 12/12/2022] Open
Abstract
The β subunit of voltage-gated Ca2+ (CaV) channels plays an important role in regulating gating of the α1 pore-forming subunit and its regulation by phosphatidylinositol 4,5-bisphosphate (PIP2). Subcellular localization of the CaV β subunit is critical for this effect; N-terminal-dependent membrane targeting of the β subunit slows inactivation and decreases PIP2 sensitivity. Here, we provide evidence that the HOOK region of the β subunit plays an important role in the regulation of CaV biophysics. Based on amino acid composition, we broadly divide the HOOK region into three domains: S (polyserine), A (polyacidic), and B (polybasic). We show that a β subunit containing only its A domain in the HOOK region increases inactivation kinetics and channel inhibition by PIP2 depletion, whereas a β subunit with only a B domain decreases these responses. When both the A and B domains are deleted, or when the entire HOOK region is deleted, the responses are elevated. Using a peptide-to-liposome binding assay and confocal microscopy, we find that the B domain of the HOOK region directly interacts with anionic phospholipids via polybasic and two hydrophobic Phe residues. The β2c-short subunit, which lacks an A domain and contains fewer basic amino acids and no Phe residues in the B domain, neither associates with phospholipids nor affects channel gating dynamically. Together, our data suggest that the flexible HOOK region of the β subunit acts as an important regulator of CaV channel gating via dynamic electrostatic and hydrophobic interaction with the plasma membrane.
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Affiliation(s)
- Cheon-Gyu Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Korea
| | - Yongsoo Park
- Izmir International Biomedicine and Genome Institute (iBG-izmir), Dokuz Eylul University, 35340 Balcova, Izmir, Turkey
| | - Byung-Chang Suh
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Korea
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12
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Zuccolo E, Dragoni S, Poletto V, Catarsi P, Guido D, Rappa A, Reforgiato M, Lodola F, Lim D, Rosti V, Guerra G, Moccia F. Arachidonic acid-evoked Ca 2+ signals promote nitric oxide release and proliferation in human endothelial colony forming cells. Vascul Pharmacol 2016; 87:159-171. [PMID: 27634591 DOI: 10.1016/j.vph.2016.09.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 06/10/2016] [Accepted: 09/10/2016] [Indexed: 02/04/2023]
Abstract
Arachidonic acid (AA) stimulates endothelial cell (EC) proliferation through an increase in intracellular Ca2+ concentration ([Ca2+]i), that, in turn, promotes nitric oxide (NO) release. AA-evoked Ca2+ signals are mainly mediated by Transient Receptor Potential Vanilloid 4 (TRPV4) channels. Circulating endothelial colony forming cells (ECFCs) represent the only established precursors of ECs. In the present study, we, therefore, sought to elucidate whether AA promotes human ECFC (hECFC) proliferation through an increase in [Ca2+]i and the following activation of the endothelial NO synthase (eNOS). AA induced a dose-dependent [Ca2+]i raise that was mimicked by its non-metabolizable analogue eicosatetraynoic acid. AA-evoked Ca2+ signals required both intracellular Ca2+ release and external Ca2+ inflow. AA-induced Ca2+ release was mediated by inositol-1,4,5-trisphosphate receptors from the endoplasmic reticulum and by two pore channel 1 from the acidic stores of the endolysosomal system. AA-evoked Ca2+ entry was, in turn, mediated by TRPV4, while it did not involve store-operated Ca2+ entry. Moreover, AA caused an increase in NO levels which was blocked by preventing the concomitant increase in [Ca2+]i and by inhibiting eNOS activity with NG-nitro-l-arginine methyl ester (l-NAME). Finally, AA per se did not stimulate hECFC growth, but potentiated growth factors-induced hECFC proliferation in a Ca2+- and NO-dependent manner. Therefore, AA-evoked Ca2+ signals emerge as an additional target to prevent cancer vascularisation, which may be sustained by ECFC recruitment.
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Affiliation(s)
- Estella Zuccolo
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Silvia Dragoni
- Department of Cell Biology, Institute of Ophthalmology, University College London, 11-43 Bath Street, EC1V 9EL London, United Kingdom
| | - Valentina Poletto
- Center for the Study of Myelofibrosis, Biotechnology Research Laboratory, Fondazione IRCCS Policlinico San Matteo, 27100 Pavia, Italy
| | - Paolo Catarsi
- Center for the Study of Myelofibrosis, Biotechnology Research Laboratory, Fondazione IRCCS Policlinico San Matteo, 27100 Pavia, Italy
| | - Daniele Guido
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Alessandra Rappa
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Marta Reforgiato
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Francesco Lodola
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Dmitry Lim
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale "Amedeo Avogadro", 28100 Novara, Italy
| | - Vittorio Rosti
- Center for the Study of Myelofibrosis, Biotechnology Research Laboratory, Fondazione IRCCS Policlinico San Matteo, 27100 Pavia, Italy
| | - Germano Guerra
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, 86100 Campobasso, Italy
| | - Francesco Moccia
- Department of Cell Biology, Institute of Ophthalmology, University College London, 11-43 Bath Street, EC1V 9EL London, United Kingdom.
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13
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Kim DI, Kweon HJ, Park Y, Jang DJ, Suh BC. Ca2+ controls gating of voltage-gated calcium channels by releasing the β2e subunit from the plasma membrane. Sci Signal 2016; 9:ra67. [PMID: 27382026 DOI: 10.1126/scisignal.aad7247] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Voltage-gated calcium (Cav) channels, which are regulated by membrane potential, cytosolic Ca(2+), phosphorylation, and membrane phospholipids, govern Ca(2+) entry into excitable cells. Cav channels contain a pore-forming α1 subunit, an auxiliary α2δ subunit, and a regulatory β subunit, each encoded by several genes in mammals. In addition to a domain that interacts with the α1 subunit, β2e and β2a also interact with the cytoplasmic face of the plasma membrane through an electrostatic interaction for β2e and posttranslational acylation for β2a. We found that an increase in cytosolic Ca(2+) promoted the release of β2e from the membrane without requiring substantial depletion of the anionic phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) from the plasma membrane. Experiments with liposomes indicated that Ca(2+) disrupted the interaction of the β2e amino-terminal peptide with membranes containing PIP2 Ca(2+) binding to calmodulin (CaM) leads to CaM-mediated inactivation of Cav currents. Although Cav2.2 coexpressed with β2a required Ca(2+)-dependent activation of CaM for Ca(2+)-mediated reduction in channel activity, Cav2.2 coexpressed with β2e exhibited Ca(2+)-dependent inactivation of the channel even in the presence of Ca(2+)-insensitive CaM. Inducible depletion of PIP2 reduced Cav2.2 currents, and in cells coexpressing β2e, but not a form that lacks the polybasic region, increased intracellular Ca(2+) further reduced Cav2.2 currents. Many hormone- or neurotransmitter-activated receptors stimulate PIP2 hydrolysis and increase cytosolic Ca(2+); thus, our findings suggest that β2e may integrate such receptor-mediated signals to limit Cav activity.
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Affiliation(s)
- Dong-Il Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Hae-Jin Kweon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Yongsoo Park
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Deok-Jin Jang
- Department of Ecological Science, College of Ecology and Environment, Kyungpook National University, Kyungbuk 742-711, Korea
| | - Byung-Chang Suh
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea.
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14
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Molecular Basis of the Membrane Interaction of the β2e Subunit of Voltage-Gated Ca(2+) Channels. Biophys J 2016; 109:922-35. [PMID: 26331250 DOI: 10.1016/j.bpj.2015.07.040] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 07/27/2015] [Accepted: 07/28/2015] [Indexed: 12/30/2022] Open
Abstract
The auxiliary β subunit plays an important role in the regulation of voltage-gated calcium (CaV) channels. Recently, it was revealed that β2e associates with the plasma membrane through an electrostatic interaction between N-terminal basic residues and anionic phospholipids. However, a molecular-level understanding of β-subunit membrane recruitment in structural detail has remained elusive. In this study, using a combination of site-directed mutagenesis, liposome-binding assays, and multiscale molecular-dynamics (MD) simulation, we developed a physical model of how the β2e subunit is recruited electrostatically to the plasma membrane. In a fluorescence resonance energy transfer assay with liposomes, binding of the N-terminal peptide (23 residues) to liposome was significantly increased in the presence of phosphatidylserine (PS) and phosphatidylinositol 4,5-bisphosphate (PIP2). A mutagenesis analysis suggested that two basic residues proximal to Met-1, Lys-2 (K2) and Trp-5 (W5), are more important for membrane binding of the β2e subunit than distal residues from the N-terminus. Our MD simulations revealed that a stretched binding mode of the N-terminus to PS is required for stable membrane attachment through polar and nonpolar interactions. This mode obtained from MD simulations is consistent with experimental results showing that K2A, W5A, and K2A/W5A mutants failed to be targeted to the plasma membrane. We also investigated the effects of a mutated β2e subunit on inactivation kinetics and regulation of CaV channels by PIP2. In experiments with voltage-sensing phosphatase (VSP), a double mutation in the N-terminus of β2e (K2A/W5A) increased the PIP2 sensitivity of CaV2.2 and CaV1.3 channels by ∼3-fold compared with wild-type β2e subunit. Together, our results suggest that membrane targeting of the β2e subunit is initiated from the nonspecific electrostatic insertion of N-terminal K2 and W5 residues into the membrane. The PS-β2e interaction observed here provides a molecular insight into general principles for protein binding to the plasma membrane, as well as the regulatory roles of phospholipids in transporters and ion channels.
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15
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Kawanabe A, Okamura Y. Effects of unsaturated fatty acids on the kinetics of voltage-gated proton channels heterologously expressed in cultured cells. J Physiol 2016; 594:595-610. [PMID: 26563684 DOI: 10.1113/jp271274] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 10/28/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Arachidonic acid (AA) greatly enhances the activity of the voltage-gated proton (Hv) channel, although its mechanism of action and physiological function remain unclear. In the present study, we analysed the effects of AA on proton currents through Hv channels heterologously expressed in HEK293T cells. The dramatic increase in proton current amplitude elicited by AA was accompanied by accelerated activation kinetics and a leftward shift in the voltage-dependence of activation. Mutagenesis studies suggest the two aforementioned effects of AA reflect two distinct structural mechanisms. Application of phospholipase A2 , which liberates AA from phospholipids in the membrane, also enhances Hv channel activity, supporting the idea that AA modulates Hv channel activity within physiological contexts. Unsaturated fatty acids are key components of the biological membranes of all cells, and precursors of mediators for cell signalling. Arachidonic acid (AA) is an unsaturated fatty acid known to modulate the activities of various ion channels, including the voltage-gated proton (Hv) channel, which supports the rapid production of reactive oxygen species (ROS) in phagocytes through regulation of pH and membrane potential. However, the molecular mechanisms and physiological functions of the effects of AA on Hv channels remain unclear. In the present study, we report an electrophysiological analysis of the effects of AA on the mouse Hv channel (mHv1) heterologously expressed in HEK293T cells. Application of AA to excised inside-out patch membranes rapidly induced a robust increase in the amplitude of the proton current through mHv1. The current increase was accompanied by accelerated activation kinetics and a small leftward shift of the current-voltage relationship. In monomeric channels lacking the coiled-coil region of the channel protein, the shift in the current-voltage relationship was diminished but activation and deactivation remained accelerated. Studies with several AA derivatives showed that double bonds and hydrophilic head groups are essential for the effect of AA, although charge was not important. The application of phospholipase A2 (PLA2), which generates AA from cell membrane phospholipids, stimulated mHv1 activity to a similar extent as direct application of ∼ 20 μM AA, suggesting that endogenous AA may regulate Hv channel activity.
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Affiliation(s)
- Akira Kawanabe
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.,Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Yasushi Okamura
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.,Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan.,Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
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16
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Systems biology of ion channels and transporters in tumor angiogenesis: An omics view. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:2647-56. [DOI: 10.1016/j.bbamem.2014.10.031] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 10/09/2014] [Accepted: 10/20/2014] [Indexed: 01/19/2023]
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17
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Optimization of neuronal cultures from rat superior cervical ganglia for dual patch recording. Sci Rep 2015; 5:14455. [PMID: 26399440 PMCID: PMC4585864 DOI: 10.1038/srep14455] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 08/12/2015] [Indexed: 12/29/2022] Open
Abstract
Superior cervical ganglion neurons (SCGN) are often used to investigate neurotransmitter release mechanisms. In this study, we optimized the dissociation and culture conditions of rat SCGN cultures for dual patch clamp recordings. Two weeks in vitro are sufficient to achieve a significant CNTF-induced cholinergic switch and to develop mature and healthy neuronal profiles suited for detailed patch clamp analysis. One single pup provides sufficient material to prepare what was formerly obtained from 12 to 15 animals. The suitability of these cultures to study neurotransmitter release mechanisms was validated by presynaptically perturbing the interaction of the v-SNARE VAMP2 with the vesicular V-ATPase V0c subunit.
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18
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Zhu L, McDavid S, Currie KPM. "Slow" Voltage-Dependent Inactivation of CaV2.2 Calcium Channels Is Modulated by the PKC Activator Phorbol 12-Myristate 13-Acetate (PMA). PLoS One 2015. [PMID: 26222492 PMCID: PMC4519294 DOI: 10.1371/journal.pone.0134117] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
CaV2.2 (N-type) voltage-gated calcium channels (Ca2+ channels) play key roles in neurons and neuroendocrine cells including the control of cellular excitability, neurotransmitter / hormone secretion, and gene expression. Calcium entry is precisely controlled by channel gating properties including multiple forms of inactivation. “Fast” voltage-dependent inactivation is relatively well-characterized and occurs over the tens-to- hundreds of milliseconds timeframe. Superimposed on this is the molecularly distinct, but poorly understood process of “slow” voltage-dependent inactivation, which develops / recovers over seconds-to-minutes. Protein kinases can modulate “slow” inactivation of sodium channels, but little is known about if/how second messengers control “slow” inactivation of Ca2+ channels. We investigated this using recombinant CaV2.2 channels expressed in HEK293 cells and native CaV2 channels endogenously expressed in adrenal chromaffin cells. The PKC activator phorbol 12-myristate 13-acetate (PMA) dramatically prolonged recovery from “slow” inactivation, but an inactive control (4α-PMA) had no effect. This effect of PMA was prevented by calphostin C, which targets the C1-domain on PKC, but only partially reduced by inhibitors that target the catalytic domain of PKC. The subtype of the channel β-subunit altered the kinetics of inactivation but not the magnitude of slowing produced by PMA. Intracellular GDP-β-S reduced the effect of PMA suggesting a role for G proteins in modulating “slow” inactivation. We postulate that the kinetics of recovery from “slow” inactivation could provide a molecular memory of recent cellular activity and help control CaV2 channel availability, electrical excitability, and neurotransmission in the seconds-to-minutes timeframe.
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Affiliation(s)
- Lei Zhu
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Sarah McDavid
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Kevin P. M. Currie
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
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19
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Calloway N, Gouzer G, Xue M, Ryan TA. The active-zone protein Munc13 controls the use-dependence of presynaptic voltage-gated calcium channels. eLife 2015. [PMID: 26196145 PMCID: PMC4525472 DOI: 10.7554/elife.07728] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Presynaptic calcium channel function is critical for converting electrical information into chemical communication but the molecules in the active zone that sculpt this function are poorly understood. We show that Munc13, an active-zone protein essential for exocytosis, also controls presynaptic voltage-gated calcium channel (VGCC) function dictating their behavior during various forms of activity. We demonstrate that in vitro Munc13 interacts with voltage-VGCCs via a pair of basic residues in Munc13's C2B domain. We show that elimination of this interaction by either removal of Munc13 or replacement of Munc13 with a Munc13 C2B mutant alters synaptic VGCC's response to and recovery from high-frequency action potential bursts and alters calcium influx from single action potential stimuli. These studies illustrate a novel form of synaptic modulation and show that Munc13 is poised to profoundly impact information transfer at nerve terminals by controlling both vesicle priming and the trigger for exocytosis.
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Affiliation(s)
- Nathaniel Calloway
- Department of Biochemistry, Weill Cornell Medical College, New York, United States
| | - Géraldine Gouzer
- Department of Biochemistry, Weill Cornell Medical College, New York, United States
| | - Mingyu Xue
- Department of Biochemistry, Weill Cornell Medical College, New York, United States
| | - Timothy A Ryan
- Department of Biochemistry, Weill Cornell Medical College, New York, United States
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20
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Roberts-Crowley ML, Rittenhouse AR. Characterization of ST14A Cells for Studying Modulation of Voltage-Gated Calcium Channels. PLoS One 2015; 10:e0132469. [PMID: 26147123 PMCID: PMC4492559 DOI: 10.1371/journal.pone.0132469] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/15/2015] [Indexed: 11/19/2022] Open
Abstract
In medium spiny neurons (MSNs) of the striatum, dopamine D2 receptors (D2Rs) specifically inhibit the Cav1.3 subtype of L-type Ca2+ channels (LTCs). MSNs are heterogeneous in their expression of dopamine receptors making the study of D2R pathways difficult in primary neurons. Here, we employed the ST14A cell line, derived from embryonic striatum and characterized to have properties of MSNs, to study Cav1.3 current and its modulation by neurotransmitters. Round, undifferentiated ST14A cells exhibited little to no endogenous Ca2+ current while differentiated ST14A cells expressed endogenous Ca2+ current. Transfection with LTC subunits produced functional Cav1.3 current from round cells, providing a homogeneous model system compared to native MSNs for studying D2R pathways. However, neither endogenous nor recombinant Cav1.3 current was modulated by the D2R agonist quinpirole. We confirmed D2R expression in ST14A cells and also detected D1Rs, D4Rs, D5Rs, Gq, calcineurin and phospholipase A2 using RT-PCR and/or Western blot analysis. Phospholipase C β-1 (PLCβ-1) expression was not detected by Western blot analysis which may account for the lack of LTC modulation by D2Rs. These findings raise caution about the assumption that the presence of G-protein coupled receptors in cell lines indicates the presence of complete signaling cascades. However, exogenous arachidonic acid inhibited recombinant Cav1.3 current indicating that channels expressed in ST14A cells are capable of modulation since they respond to a known signaling molecule downstream of D2Rs. Thus, ST14A cells provide a MSN-like cell line for studying channel modulation and signaling pathways that do not involve activation of PLCβ-1.
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Affiliation(s)
- Mandy L. Roberts-Crowley
- Department of Physiology, Program in Neuroscience, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Ann R. Rittenhouse
- Department of Physiology, Program in Neuroscience, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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21
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Kaur G, Pinggera A, Ortner NJ, Lieb A, Sinnegger-Brauns MJ, Yarov-Yarovoy V, Obermair GJ, Flucher BE, Striessnig J. A Polybasic Plasma Membrane Binding Motif in the I-II Linker Stabilizes Voltage-gated CaV1.2 Calcium Channel Function. J Biol Chem 2015; 290:21086-21100. [PMID: 26100638 PMCID: PMC4543666 DOI: 10.1074/jbc.m115.645671] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Indexed: 12/27/2022] Open
Abstract
L-type voltage-gated Ca(2+) channels (LTCCs) regulate many physiological functions like muscle contraction, hormone secretion, gene expression, and neuronal excitability. Their activity is strictly controlled by various molecular mechanisms. The pore-forming α1-subunit comprises four repeated domains (I-IV), each connected via an intracellular linker. Here we identified a polybasic plasma membrane binding motif, consisting of four arginines, within the I-II linker of all LTCCs. The primary structure of this motif is similar to polybasic clusters known to interact with polyphosphoinositides identified in other ion channels. We used de novo molecular modeling to predict the conformation of this polybasic motif, immunofluorescence microscopy and live cell imaging to investigate the interaction with the plasma membrane, and electrophysiology to study its role for Cav1.2 channel function. According to our models, this polybasic motif of the I-II linker forms a straight α-helix, with the positive charges facing the lipid phosphates of the inner leaflet of the plasma membrane. Membrane binding of the I-II linker could be reversed after phospholipase C activation, causing polyphosphoinositide breakdown, and was accelerated by elevated intracellular Ca(2+) levels. This indicates the involvement of negatively charged phospholipids in the plasma membrane targeting of the linker. Neutralization of four arginine residues eliminated plasma membrane binding. Patch clamp recordings revealed facilitated opening of Cav1.2 channels containing these mutations, weaker inhibition by phospholipase C activation, and reduced expression of channels (as quantified by ON-gating charge) at the plasma membrane. Our data provide new evidence for a membrane binding motif within the I-II linker of LTCC α1-subunits essential for stabilizing normal Ca(2+) channel function.
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Affiliation(s)
- Gurjot Kaur
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Alexandra Pinggera
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Nadine J Ortner
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Andreas Lieb
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Martina J Sinnegger-Brauns
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, UC Davis School of Medicine, Davis, California 95616
| | - Gerald J Obermair
- Division of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Bernhard E Flucher
- Division of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Jörg Striessnig
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria.
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22
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Kim DI, Park Y, Jang DJ, Suh BC. Dynamic phospholipid interaction of β2e subunit regulates the gating of voltage-gated Ca2+ channels. ACTA ACUST UNITED AC 2015; 145:529-41. [PMID: 25964431 PMCID: PMC4442786 DOI: 10.1085/jgp.201411349] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 04/10/2015] [Indexed: 12/18/2022]
Abstract
Membrane targeting of the β2e subunit is dynamically regulated by M1 muscarinic receptor signaling to promote fast inactivation of CaV2.2. High voltage-activated Ca2+ (CaV) channels are protein complexes containing pore-forming α1 and auxiliary β and α2δ subunits. The subcellular localization and membrane interactions of the β subunits play a crucial role in regulating CaV channel inactivation and its lipid sensitivity. Here, we investigated the effects of membrane phosphoinositide (PI) turnover on CaV2.2 channel function. The β2 isoform β2e associates with the membrane through electrostatic and hydrophobic interactions. Using chimeric β subunits and liposome-binding assays, we determined that interaction between the N-terminal 23 amino acids of β2e and anionic phospholipids was sufficient for β2e membrane targeting. Binding of the β2e subunit N terminus to liposomes was significantly increased by inclusion of 1% phosphatidylinositol 4,5-bisphosphate (PIP2) in the liposomes, suggesting that, in addition to phosphatidylserine, PIs are responsible for β2e targeting to the plasma membrane. Membrane binding of the β2e subunit slowed CaV2.2 current inactivation. When membrane phosphatidylinositol 4-phosphate and PIP2 were depleted by rapamycin-induced translocation of pseudojanin to the membrane, however, channel opening was decreased and fast inactivation of CaV2.2(β2e) currents was enhanced. Activation of the M1 muscarinic receptor elicited transient and reversible translocation of β2e subunits from membrane to cytosol, but not that of β2a or β3, resulting in fast inactivation of CaV2.2 channels with β2e. These results suggest that membrane targeting of the β2e subunit, which is mediated by nonspecific electrostatic insertion, is dynamically regulated by receptor stimulation, and that the reversible association of β2e with membrane PIs results in functional changes in CaV channel gating. The phospholipid–protein interaction observed here provides structural insight into mechanisms of membrane–protein association and the role of phospholipids in ion channel regulation.
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Affiliation(s)
- Dong-Il Kim
- Department of Brain Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873, Korea
| | - Yongsoo Park
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Deok-Jin Jang
- Department of Ecological Science, College of Ecology and Environment, Kyungpook National University, Kyungbuk 742-711, Korea
| | - Byung-Chang Suh
- Department of Brain Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873, Korea
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23
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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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24
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Hermann PM, Watson SN, Wildering WC. Phospholipase A2 - nexus of aging, oxidative stress, neuronal excitability, and functional decline of the aging nervous system? Insights from a snail model system of neuronal aging and age-associated memory impairment. Front Genet 2014; 5:419. [PMID: 25538730 PMCID: PMC4255604 DOI: 10.3389/fgene.2014.00419] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 11/13/2014] [Indexed: 02/02/2023] Open
Abstract
The aging brain undergoes a range of changes varying from subtle structural and physiological changes causing only minor functional decline under healthy normal aging conditions, to severe cognitive or neurological impairment associated with extensive loss of neurons and circuits due to age-associated neurodegenerative disease conditions. Understanding how biological aging processes affect the brain and how they contribute to the onset and progress of age-associated neurodegenerative diseases is a core research goal in contemporary neuroscience. This review focuses on the idea that changes in intrinsic neuronal electrical excitability associated with (per)oxidation of membrane lipids and activation of phospholipase A2 (PLA2) enzymes are an important mechanism of learning and memory failure under normal aging conditions. Specifically, in the context of this special issue on the biology of cognitive aging we portray the opportunities offered by the identifiable neurons and behaviorally characterized neural circuits of the freshwater snail Lymnaea stagnalis in neuronal aging research and recapitulate recent insights indicating a key role of lipid peroxidation-induced PLA2 as instruments of aging, oxidative stress and inflammation in age-associated neuronal and memory impairment in this model system. The findings are discussed in view of accumulating evidence suggesting involvement of analogous mechanisms in the etiology of age-associated dysfunction and disease of the human and mammalian brain.
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Affiliation(s)
- Petra M Hermann
- Department of Biological Sciences, University of Calgary Calgary, AB, Canada ; Department of Physiology and Pharmacology, University of Calgary Calgary, AB, Canada
| | - Shawn N Watson
- Department of Biological Sciences, University of Calgary Calgary, AB, Canada
| | - Willem C Wildering
- Department of Biological Sciences, University of Calgary Calgary, AB, Canada ; Department of Physiology and Pharmacology, University of Calgary Calgary, AB, Canada ; Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
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Morales-Lázaro SL, Rosenbaum T. A painful link between the TRPV1 channel and lysophosphatidic acid. Life Sci 2014; 125:15-24. [PMID: 25445434 DOI: 10.1016/j.lfs.2014.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/30/2014] [Accepted: 10/04/2014] [Indexed: 10/24/2022]
Abstract
The Transient Receptor Potential Vanilloid 1 (TRPV1) ion channel is expressed mainly by sensory neurons that detect noxious stimuli from the environment such as high temperatures and pungent compounds (such as allicin and capsaicin) and has been extensively linked to painful and inflammatory processes. This extraordinary protein also responds to endogenous stimuli among which we find molecules of a lipidic nature. We recently described that lysophosphatidic acid (LPA), a bioactive lysophospholipid linked to the generation and maintenance of pain, can directly activate TRPV1 and produce pain by binding to the channels' C-terminal region, specifically to residue K710. In an effort to further understand how activation of TRPV1 is achieved by this negatively-charged lipid, we used several synthetic and naturally-occurring lipids to determine the structural requirements that need to be met by these charged lipids in order to produce the activation of TRPV1. In this review, we detail the findings obtained by other research groups and our own on the field of TRPV1-regulation by negatively-charged lipids and discuss the possible therapeutic relevance of these findings on the basis of the role of TRPV1 in pathophysiological processes.
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Affiliation(s)
- Sara L Morales-Lázaro
- Departamento de Neurodesarrollo y Fisiología, División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México
| | - Tamara Rosenbaum
- Departamento de Neurodesarrollo y Fisiología, División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México.
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26
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Exogenous α-synuclein decreases raft partitioning of Cav2.2 channels inducing dopamine release. J Neurosci 2014; 34:10603-15. [PMID: 25100594 DOI: 10.1523/jneurosci.0608-14.2014] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
α-Synuclein is thought to regulate neurotransmitter release through multiple interactions with presynaptic proteins, cytoskeletal elements, ion channels, and synaptic vesicles membrane. α-Synuclein is abundant in the presynaptic compartment, and its release from neurons and glia has been described as responsible for spreading of α-synuclein-derived pathology. α-Synuclein-dependent dysregulation of neurotransmitter release might occur via its action on surface-exposed calcium channels. Here, we provide electrophysiological and biochemical evidence to show that α-synuclein, applied to rat neurons in culture or striatal slices, selectively activates Cav2.2 channels, and said activation correlates with increased neurotransmitter release. Furthermore, in vivo perfusion of α-synuclein into the striatum also leads to acute dopamine release. We further demonstrate that α-synuclein reduces the amount of plasma membrane cholesterol and alters the partitioning of Cav2.2 channels, which move from raft to cholesterol-poor areas of the plasma membrane. We provide evidence for a novel mechanism through which α-synuclein acts from the extracellular milieu to modulate neurotransmitter release and propose a unifying hypothesis for the mechanism of α-synuclein action on multiple targets: the reorganization of plasma membrane microdomains.
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Logothetis DE, Petrou VI, Zhang M, Mahajan R, Meng XY, Adney SK, Cui M, Baki L. Phosphoinositide control of membrane protein function: a frontier led by studies on ion channels. Annu Rev Physiol 2014; 77:81-104. [PMID: 25293526 DOI: 10.1146/annurev-physiol-021113-170358] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Anionic phospholipids are critical constituents of the inner leaflet of the plasma membrane, ensuring appropriate membrane topology of transmembrane proteins. Additionally, in eukaryotes, the negatively charged phosphoinositides serve as key signals not only through their hydrolysis products but also through direct control of transmembrane protein function. Direct phosphoinositide control of the activity of ion channels and transporters has been the most convincing case of the critical importance of phospholipid-protein interactions in the functional control of membrane proteins. Furthermore, second messengers, such as [Ca(2+)]i, or posttranslational modifications, such as phosphorylation, can directly or allosterically fine-tune phospholipid-protein interactions and modulate activity. Recent advances in structure determination of membrane proteins have allowed investigators to obtain complexes of ion channels with phosphoinositides and to use computational and experimental approaches to probe the dynamic mechanisms by which lipid-protein interactions control active and inactive protein states.
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Affiliation(s)
- Diomedes E Logothetis
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298-0551;
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28
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Collins MD, Gordon SE. Short-chain phosphoinositide partitioning into plasma membrane models. Biophys J 2014; 105:2485-94. [PMID: 24314079 DOI: 10.1016/j.bpj.2013.09.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 08/20/2013] [Accepted: 09/23/2013] [Indexed: 10/26/2022] Open
Abstract
Phosphoinositides are vital for many cellular signaling processes, and therefore a number of approaches to manipulating phosphoinositide levels in cells or excised patches of cell membranes have been developed. Among the most common is the use of "short-chain" phosphoinositides, usually dioctanoyl phosphoinositol phosphates. We use isothermal titration calorimetry to determine partitioning of the most abundant phosphoinositol phosphates, PI(4)P and PI(4,5)P2 into models of the intracellular and extracellular facing leaflets of neuronal plasma membranes. We show that phosphoinositide mole fractions in the lipid membrane reach physiological levels at equilibrium with reasonable solution concentrations. Finally we explore the consequences of our results for cellular electrophysiology. In particular, we find that TRPV1 is more selective for PI(4,5)P2 than PI(4)P and activated by extremely low membrane mole fractions of PIPs. We conclude by discussing how the logic of our work extends to other experiments with short-chain phosphoinositides. For delayed rectifier K(+) channels, consideration of the membrane mole fraction of PI(4,5)P2 lipids with different acyl chain lengths suggests a different mechanism for PI(4,5)P2 regulation than previously proposed. Inward rectifier K(+) channels apparent lack of selectivity for certain short-chain PIPs may require reinterpretation in view of the PIPs different membrane partitioning.
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Affiliation(s)
- Marcus D Collins
- University of Washington School of Medicine, Department of Physiology and Biophysics, Seattle, WA
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29
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Payandeh J, Minor DL. Bacterial voltage-gated sodium channels (BacNa(V)s) from the soil, sea, and salt lakes enlighten molecular mechanisms of electrical signaling and pharmacology in the brain and heart. J Mol Biol 2014; 427:3-30. [PMID: 25158094 DOI: 10.1016/j.jmb.2014.08.010] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 08/11/2014] [Accepted: 08/18/2014] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium channels (Na(V)s) provide the initial electrical signal that drives action potential generation in many excitable cells of the brain, heart, and nervous system. For more than 60years, functional studies of Na(V)s have occupied a central place in physiological and biophysical investigation of the molecular basis of excitability. Recently, structural studies of members of a large family of bacterial voltage-gated sodium channels (BacNa(V)s) prevalent in soil, marine, and salt lake environments that bear many of the core features of eukaryotic Na(V)s have reframed ideas for voltage-gated channel function, ion selectivity, and pharmacology. Here, we analyze the recent advances, unanswered questions, and potential of BacNa(V)s as templates for drug development efforts.
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Affiliation(s)
- Jian Payandeh
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA 94080, USA.
| | - Daniel L Minor
- Cardiovascular Research Institute, Departments of Biochemistry and Biophysics and Cellular and Molecular Pharmacology, California Institute for Quantitative Biomedical Research, University of California, San Francisco, CA 93858-2330, USA; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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30
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Zhang M, Meng XY, Cui M, Pascal JM, Logothetis DE, Zhang JF. Selective phosphorylation modulates the PIP2 sensitivity of the CaM-SK channel complex. Nat Chem Biol 2014; 10:753-9. [PMID: 25108821 DOI: 10.1038/nchembio.1592] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 06/19/2014] [Indexed: 11/09/2022]
Abstract
Phosphatidylinositol bisphosphate (PIP2) regulates the activities of many membrane proteins, including ion channels, through direct interactions. However, the affinity of PIP2 is so high for some channel proteins that its physiological role as a modulator has been questioned. Here we show that PIP2 is a key cofactor for activation of small conductance Ca2+-activated potassium channels (SKs) by Ca(2+)-bound calmodulin (CaM). Removal of the endogenous PIP2 inhibits SKs. The PIP2-binding site resides at the interface of CaM and the SK C terminus. We further demonstrate that the affinity of PIP2 for its target proteins can be regulated by cellular signaling. Phosphorylation of CaM T79, located adjacent to the PIP2-binding site, by casein kinase 2 reduces the affinity of PIP2 for the CaM-SK channel complex by altering the dynamic interactions among amino acid residues surrounding the PIP2-binding site. This effect of CaM phosphorylation promotes greater channel inhibition by G protein-mediated hydrolysis of PIP2.
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Affiliation(s)
- Miao Zhang
- 1] Department of Molecular Physiology and Biophysics, Thomas Jefferson University, Philadelphia, Pennsylvania, USA. [2] Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Xuan-Yu Meng
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Meng Cui
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - John M Pascal
- Department of Biochemistry &Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Diomedes E Logothetis
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Ji-Fang Zhang
- 1] Department of Molecular Physiology and Biophysics, Thomas Jefferson University, Philadelphia, Pennsylvania, USA. [2] Farber Institute for Neurosciences, Thomas Jefferson University, Philadelphia, Pennsylvania, USA. [3] Graduate Program in Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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31
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Yu Y, Boyer NP, Zhang C. Three structurally similar odorants trigger distinct signaling pathways in a mouse olfactory neuron. Neuroscience 2014; 275:194-210. [PMID: 24929067 DOI: 10.1016/j.neuroscience.2014.05.063] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 04/08/2014] [Accepted: 05/22/2014] [Indexed: 12/20/2022]
Abstract
In the mammalian olfactory system, one olfactory sensory neuron (OSN) expresses a single olfactory receptor gene. By calcium imaging of individual OSNs in intact mouse olfactory turbinates, we observed that a subset of OSNs (Ho-OSNs) located in the most ventral olfactory receptor zone can mediate distinct signaling pathways when activated by structurally similar ligands. Calcium imaging showed that Ho-OSNs were highly sensitive to 2-heptanone, heptaldehyde and cis-4-heptenal. 2-heptanone-evoked intracellular calcium elevation was mediated by cAMP signaling while heptaldehyde triggered the diacylglycerol pathway. An increase of intracellular calcium evoked by cis-4-heptenal was due to a combination of activation mediated by the adenylate cyclase pathway and suppression generated by phospholipase C signaling. Pharmacological studies demonstrated that novel mechanisms were involved in the phospholipase C-mediated intracellular calcium changes. Binary-mixture studies and cross-adaptation data indicate that three odorants acted on the same olfactory receptor. The feature that an olfactory receptor mediates multiple signaling pathways was specific for Ho-OSNs and not established in another population of OSNs characterized. Our study suggests that distinct signaling pathways triggered by ligand-induced conformational changes of an olfactory receptor constitute a complex information process mechanism in olfactory transduction. This study has important implications beyond olfaction in that it provides insights of plasticity and complexity of G-protein-coupled receptor activation and signal transduction.
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Affiliation(s)
- Y Yu
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, 3101 S. Dearborn Street, Chicago, IL 60616, USA
| | - N P Boyer
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC 29425, USA; Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, USA
| | - C Zhang
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, 3101 S. Dearborn Street, Chicago, IL 60616, USA.
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32
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Poveda J, Giudici A, Renart M, Molina M, Montoya E, Fernández-Carvajal A, Fernández-Ballester G, Encinar J, González-Ros J. Lipid modulation of ion channels through specific binding sites. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:1560-7. [DOI: 10.1016/j.bbamem.2013.10.023] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 10/24/2013] [Accepted: 10/30/2013] [Indexed: 01/08/2023]
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Chemin J, Cazade M, Lory P. Modulation of T-type calcium channels by bioactive lipids. Pflugers Arch 2014; 466:689-700. [PMID: 24531745 DOI: 10.1007/s00424-014-1467-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 01/24/2014] [Accepted: 01/29/2014] [Indexed: 01/10/2023]
Abstract
T-type calcium channels (T-channels/CaV3) have unique biophysical properties allowing a calcium influx at resting membrane potential of most cells. T-channels are ubiquitously expressed in many tissues and contribute to low-threshold spikes and burst firing in central neurons as well as to pacemaker activities in cardiac cells. They also emerged as potential targets to treat cancer and hypertension. Regulation of these channels appears complex, and several studies have indicated that CaV3.1, CaV3.2, and CaV3.3 currents are directly inhibited by multiple endogenous lipids independently of membrane receptors or intracellular pathways. These bioactive lipids include arachidonic acid and ω3 poly-unsaturated fatty acids; the endocannabinoid anandamide and other N-acylethanolamides; the lipoamino-acids and lipo-neurotransmitters; the P450 epoxygenase metabolite 5,6-epoxyeicosatrienoic acid; as well as similar molecules with 18-22 carbons in the alkyl chain. In this review, we summarize evidence for direct effects of these signaling molecules, the molecular mechanisms underlying the current inhibition, and the involved chemical features. The impact of this modulation in physiology and pathophysiology is discussed with a special emphasis on pain aspects and vasodilation. Overall, these data clearly indicate that T-current inhibition is an important mechanism by which bioactive lipids mediate their physiological functions.
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Affiliation(s)
- Jean Chemin
- Institut de Génomique Fonctionnelle, Universités Montpellier 1 & 2, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5203, 141, rue de la Cardonille, 34094, Montpellier cedex 05, France,
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Carta M, Lanore F, Rebola N, Szabo Z, Da Silva SV, Lourenço J, Verraes A, Nadler A, Schultz C, Blanchet C, Mulle C. Membrane lipids tune synaptic transmission by direct modulation of presynaptic potassium channels. Neuron 2014; 81:787-99. [PMID: 24486086 DOI: 10.1016/j.neuron.2013.12.028] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2013] [Indexed: 12/20/2022]
Abstract
Voltage-gated potassium (Kv) channels are involved in action potential (AP) repolarization in excitable cells. Exogenous application of membrane-derived lipids, such as arachidonic acid (AA), regulates the gating of Kv channels. Whether membrane-derived lipids released under physiological conditions have an impact on neuronal coding through this mechanism is unknown. We show that AA released in an activity-dependent manner from postsynaptic hippocampal CA3 pyramidal cells acts as retrograde messenger, inducing a robust facilitation of mossy fiber (Mf) synaptic transmission over several minutes. AA acts by broadening presynaptic APs through the direct modulation of Kv channels. This form of short-term plasticity can be triggered when postsynaptic cell fires with physiologically relevant patterns and sets the threshold for the induction of the presynaptic form of long-term potentiation (LTP) at hippocampal Mf synapses. Hence, direct modulation of presynaptic Kv channels by activity-dependent release of lipids serves as a physiological mechanism for tuning synaptic transmission.
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Affiliation(s)
- Mario Carta
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Frederic Lanore
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Nelson Rebola
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Zsolt Szabo
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Silvia Viana Da Silva
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Joana Lourenço
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Agathe Verraes
- Institut Jacques Monod, UMR 7592, CNRS and INSERM ERL U950, University Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - André Nadler
- EMBL Heidelberg, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Carsten Schultz
- EMBL Heidelberg, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Christophe Blanchet
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Christophe Mulle
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France.
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Striessnig J, Pinggera A, Kaur G, Bock G, Tuluc P. L-type Ca 2+ channels in heart and brain. ACTA ACUST UNITED AC 2014; 3:15-38. [PMID: 24683526 PMCID: PMC3968275 DOI: 10.1002/wmts.102] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
L-type calcium channels (Cav1) represent one of the three major classes (Cav1–3) of voltage-gated calcium channels. They were identified as the target of clinically used calcium channel blockers (CCBs; so-called calcium antagonists) and were the first class accessible to biochemical characterization. Four of the 10 known α1 subunits (Cav1.1–Cav1.4) form the pore of L-type calcium channels (LTCCs) and contain the high-affinity drug-binding sites for dihydropyridines and other chemical classes of organic CCBs. In essentially all electrically excitable cells one or more of these LTCC isoforms is expressed, and therefore it is not surprising that many body functions including muscle, brain, endocrine, and sensory function depend on proper LTCC activity. Gene knockouts and inherited human diseases have allowed detailed insight into the physiological and pathophysiological role of these channels. Genome-wide association studies and analysis of human genomes are currently providing even more hints that even small changes of channel expression or activity may be associated with disease, such as psychiatric disease or cardiac arrhythmias. Therefore, it is important to understand the structure–function relationship of LTCC isoforms, their differential contribution to physiological function, as well as their fine-tuning by modulatory cellular processes.
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Affiliation(s)
- Jörg Striessnig
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Alexandra Pinggera
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Gurjot Kaur
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Gabriella Bock
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Petronel Tuluc
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
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Zhong D, Blount P. Phosphatidylinositol is crucial for the mechanosensitivity of Mycobacterium tuberculosis MscL. Biochemistry 2013; 52:5415-20. [PMID: 23875651 DOI: 10.1021/bi400790j] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The bacterial mechanosensitive channel of large conductance (MscL) directly senses and responds to membrane tension. It serves as an "emergency release valve" upon acute decreases in the osmotic environment, thus preventing cell lysis. It is one of the best studied mechanosensitive channels and serves as a paradigm of how a channel senses and responds to its membrane environment. The MscL protein is highly conserved, found throughout the bacterial kingdom, and has been shown to encode a functional mechanosensitive channel in all species where it has been studied. However, channels from different species have shown some functional variance; an extreme example is the Mycobacterium tuberculosis MscL, which when heterologously expressed in Escherichia coli requires significantly more membrane tension for gating than the endogenous E. coli MscL. We previously speculated that the membrane environment or factors not found in E. coli promoted the proper gating of the M. tuberculosis MscL channel in its native environment. Here, by reconstituting the M. tuberculosis and E. coli MscL channels in various lipids, we demonstrate that inclusion of phosphatidylinositol, a lipid found in M. tuberculosis but not E. coli, is sufficient for gating of the M. tuberculosis MscL channel within a physiological range of membrane tension.
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Affiliation(s)
- Dalian Zhong
- Department of Physiology, UT Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-9040, USA
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37
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Semenov I, Xiao S, Pakhomov AG. Primary pathways of intracellular Ca(2+) mobilization by nanosecond pulsed electric field. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:981-9. [PMID: 23220180 DOI: 10.1016/j.bbamem.2012.11.032] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 11/21/2012] [Accepted: 11/27/2012] [Indexed: 02/03/2023]
Abstract
Permeabilization of cell membranous structures by nanosecond pulsed electric field (nsPEF) triggers transient rise of cytosolic Ca(2+) concentration ([Ca(2+)](i)), which determines multifarious downstream effects. By using fast ratiometric Ca(2+) imaging with Fura-2, we quantified the external Ca(2+) uptake, compared it with Ca(2+) release from the endoplasmic reticulum (ER), and analyzed the interplay of these processes. We utilized CHO cells which lack voltage-gated Ca(2+) channels, so that the nsPEF-induced [Ca(2+)](i) changes could be attributed primarily to electroporation. We found that a single 60-ns pulse caused fast [Ca(2+)](i) increase by Ca(2+) influx from the outside and Ca(2+) efflux from the ER, with the E-field thresholds of about 9 and 19kV/cm, respectively. Above these thresholds, the amplitude of [Ca(2+)](i) response increased linearly by 8-10nM per 1kV/cm until a critical level between 200 and 300nM of [Ca(2+)](i) was reached. If the critical level was reached, the nsPEF-induced Ca(2+) signal was amplified up to 3000nM by engaging the physiological mechanism of Ca(2+)-induced Ca(2+)-release (CICR). The amplification was prevented by depleting Ca(2+) from the ER store with 100nM thapsigargin, as well as by blocking the ER inositol-1,4,5-trisphosphate receptors (IP(3)R) with 50μM of 2-aminoethoxydiphenyl borate (2-APB). Mobilization of [Ca(2+)](i) by nsPEF mimicked native Ca(2+) signaling, but without preceding activation of plasma membrane receptors or channels. NsPEF stimulation may serve as a unique method to mobilize [Ca(2+)](i) and activate downstream cascades while bypassing the plasma membrane receptors.
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Affiliation(s)
- Iurii Semenov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA.
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38
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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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Ireland MF, Funk GD, Bellingham MC. Muscarinic acetylcholine receptors enhance neonatal mouse hypoglossal motoneuron excitability in vitro. J Appl Physiol (1985) 2012; 113:1024-39. [DOI: 10.1152/japplphysiol.00699.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In brain stem slices from neonatal ( postnatal days 0–4) CD-1 mice, muscarinic ACh receptors (MAChRs) increased rhythmic inspiratory-related and tonic hypoglossal nerve discharge and depolarized single hypoglossal motoneurons (HMs) via an inward current without changing input resistance. These responses were blocked by the MAChR antagonist 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP; 100 nM). MAChRs shifted voltage-dependent activation of the hyperpolarization-activated cation current to more positive levels. MAChRs increased the HM repetitive firing rate and decreased rheobase, with both effects being blocked by 4-DAMP. Muscarinic agonists reduced the afterhyperpolarization of single action potentials (APs), suggesting that small-conductance Ca2+-dependent K+ current inhibition increased the HM firing rate. Muscarinic agonists also reduced the AP amplitude and slowed its time course, suggesting that MAChRs inhibited voltage-gated Na+ channels. To compare muscarinic excitation of single HMs to muscarinic excitatory effects on motor output in thicker brain stem slices requiring higher extracellular K+ for rhythmic activity, we tested the effects of muscarinic agonists on single HM excitability in high-K+ artificial cerebrospinal fluid (aCSF). In high-K+ aCSF, muscarinic agonists still depolarized HMs and altered AP size and shape, as in standard aCSF, but did not increase the steady-state firing rate, decrease afterhyperpolarization, or alter threshold potential. These results indicate that the basic cellular response of HMs to muscarinic receptors is excitatory, via a number of distinct mechanisms, and that this excitatory response will be largely preserved in rhythmically active brain stem slices.
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Affiliation(s)
- Matthew F. Ireland
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia; and
| | - Gregory D. Funk
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Mark C. Bellingham
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia; and
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Rodríguez-Menchaca AA, Adney SK, Zhou L, Logothetis DE. Dual Regulation of Voltage-Sensitive Ion Channels by PIP(2). Front Pharmacol 2012; 3:170. [PMID: 23055973 PMCID: PMC3456799 DOI: 10.3389/fphar.2012.00170] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2012] [Accepted: 09/04/2012] [Indexed: 11/13/2022] Open
Abstract
Over the past 16 years, there has been an impressive number of ion channels shown to be sensitive to the major phosphoinositide in the plasma membrane, phosphatidylinositol 4,5-bisphosphate (PIP(2)). Among them are voltage-gated channels, which are crucial for both neuronal and cardiac excitability. Voltage-gated calcium (Cav) channels were shown to be regulated bidirectionally by PIP(2). On one hand, PIP(2) stabilized their activity by reducing current rundown but on the other hand it produced a voltage-dependent inhibition by shifting the activation curve to more positive voltages. For voltage-gated potassium (Kv) channels PIP(2) was first shown to prevent N-type inactivation regardless of whether the fast inactivation gate was part of the pore-forming α subunit or of an accessory β subunit. Careful examination of the effects of PIP(2) on the activation mechanism of Kv1.2 has shown a similar bidirectional regulation as in the Cav channels. The two effects could be distinguished kinetically, in terms of their sensitivities to PIP(2) and by distinct molecular determinants. The rightward shift of the Kv1.2 voltage dependence implicated basic residues in the S4-S5 linker and was consistent with stabilization of the inactive state of the voltage sensor. A third type of a voltage-gated ion channel modulated by PIP(2) is the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel. PIP(2) has been shown to enhance the opening of HCN channels by shifting their voltage-dependent activation toward depolarized potentials. The sea urchin HCN channel, SpIH, showed again a PIP(2)-mediated bidirectional effect but in reverse order than the depolarization-activated Cav and Kv channels: a voltage-dependent potentiation, like the mammalian HCN channels, but also an inhibition of the cGMP-induced current activation. Just like the Kv1.2 channels, distinct molecular determinants underlied the PIP(2) dual effects on SpIH, with the proximal C-terminus implicated in the inhibitory effect. The dual regulation of these very different ion channels, all of which are voltage-dependent, points to conserved mechanisms of regulation of these channels by PIP(2).
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Affiliation(s)
- Aldo A Rodríguez-Menchaca
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University Richmond, VA, USA
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Buraei Z, Yang J. Structure and function of the β subunit of voltage-gated Ca²⁺ channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1530-40. [PMID: 22981275 DOI: 10.1016/j.bbamem.2012.08.028] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 08/22/2012] [Accepted: 08/25/2012] [Indexed: 12/31/2022]
Abstract
The voltage-gated Ca²⁺ channel β subunit (Ca(v)β) is a cytosolic auxiliary subunit that plays an essential role in regulating the surface expression and gating properties of high-voltage activated (HVA) Ca²⁺ channels. It is also crucial for the modulation of HVA Ca²⁺ channels by G proteins, kinases, Ras-related RGK GTPases, and other proteins. There are indications that Ca(v)β may carry out Ca²⁺ channel-independent functions. Ca(v)β knockouts are either non-viable or result in a severe pathophysiology, and mutations in Ca(v)β have been implicated in disease. In this article, we review the structure and various biological functions of Ca(v)β, as well as recent advances. This article is part of a Special Issue entitled: Calcium channels.
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Affiliation(s)
- Zafir Buraei
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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42
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Koch M, Kreutz S, Böttger C, Grabiec U, Ghadban C, Korf HW, Dehghani F. The cannabinoid WIN 55,212-2-mediated protection of dentate gyrus granule cells is driven by CB1 receptors and modulated by TRPA1 and Cav 2.2 channels. Hippocampus 2012; 21:554-64. [PMID: 20135626 DOI: 10.1002/hipo.20772] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cannabinoids regulate numerous physiological and pathological events like inflammation or neurodegeneration via CB(1) and CB(2) receptors. The mechanisms behind cannabinoid effects show a high variability and may also involve transient receptor potential channels (TRP) and N-type voltage-gated Ca(2+) channels (Ca(v) 2.2). In the present study we investigated the neuroprotective effects of the synthetic cannabinoid WIN 55,212-2 (WIN) on dentate gyrus (DG) granule cells and elucidated the involvement of TRP and Ca(v) 2.2 that are shown to participate in inflammatory processes. Organotypic hippocampal slice cultures were excitotoxically lesioned using NMDA and subsequently incubated with different WIN concentrations (0.001-10 μM). WIN showed neuroprotective properties in an inverse concentration-dependent manner, most effectively at 0.01 μM. The CB(1) receptor antagonist AM251 blocked neuroprotection mediated by WIN whereas the CB(2) receptor antagonist AM630 showed no effects. Application of the TRPA1 blocker HC-030031 enhanced the neuroprotective efficacy of high (10 μM) WIN concentrations and the number of degenerating neurons became equal to that seen after application of the most effective WIN dose (0.01 μM). In contrast, the application of TRPA1 agonist icilin or allyl isothiocyanate (AITC) led to a stronger neurodegeneration. The use of TRPV1 blocker 6-iodo-nordihydrocapsaicin did not affect WIN-mediated neuroprotection. The selective Ca(v) 2.2 blocker ω-conotoxin (GVIA) completely blocked neuroprotection shown by 10 μM WIN. GVIA and HC-030031 exerted no effects at WIN concentrations lower than 10 μM. Our data show that WIN protects dentate gyrus granule cells in a concentration dependent manner by acting upon CB(1) receptors. At high (10 μM) concentrations WIN additionally activates TRPA1 and Ca(v) 2.2 within the hippocampal formation that both interfere with CB(1) receptor-mediated neuroprotection. This leads to the conclusion that physiological and pharmacological effects of cannabinoids strongly depend on their concentration and the neuroprotective efficacy of cannabinoids may be determined by interaction of activated CB(1) receptor, TRPA1, and Ca(v) 2.2.
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Affiliation(s)
- Marco Koch
- Institut für Anatomie II, Goethe Universität Frankfurt am Main, Germany
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Membrane-localized β-subunits alter the PIP2 regulation of high-voltage activated Ca2+ channels. Proc Natl Acad Sci U S A 2012; 109:3161-6. [PMID: 22308488 DOI: 10.1073/pnas.1121434109] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The β-subunits of voltage-gated Ca(2+) (Ca(V)) channels regulate the functional expression and several biophysical properties of high-voltage-activated Ca(V) channels. We find that Ca(V) β-subunits also determine channel regulation by the membrane phospholipid phosphatidylinositol 4,5-bisphosphate (PIP(2)). When Ca(V)1.3, -2.1, or -2.2 channels are cotransfected with the β3-subunit, a cytosolic protein, they can be inhibited by activating a voltage-sensitive lipid phosphatase to deplete PIP(2). When these channels are coexpressed with a β2a-subunit, a palmitoylated peripheral membrane protein, the inhibition is much smaller. PIP(2) sensitivity could be increased by disabling the two palmitoylation sites in the β2a-subunit. To further test effects of membrane targeting of Ca(V) β-subunits on PIP(2) regulation, the N terminus of Lyn was ligated onto the cytosolic β3-subunit to confer lipidation. This chimera, like the Ca(V) β2a-subunit, displayed plasma membrane localization, slowed the inactivation of Ca(V)2.2 channels, and increased the current density. In addition, the Lyn-β3 subunit significantly decreased Ca(V) channel inhibition by PIP(2) depletion. Evidently lipidation and membrane anchoring of Ca(V) β-subunits compete with the PIP(2) regulation of high-voltage-activated Ca(V) channels. Compared with expression with Ca(V) β3-subunits alone, inhibition of Ca(V)2.2 channels by PIP(2) depletion could be significantly attenuated when β2a was coexpressed with β3. Our data suggest that the Ca(V) currents in neurons would be regulated by membrane PIP(2) to a degree that depends on their endogenous β-subunit combinations.
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Nesin V, Pakhomov AG. Inhibition of voltage-gated Na(+) current by nanosecond pulsed electric field (nsPEF) is not mediated by Na(+) influx or Ca(2+) signaling. Bioelectromagnetics 2012; 33:443-51. [PMID: 22234846 DOI: 10.1002/bem.21703] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Accepted: 12/12/2011] [Indexed: 11/10/2022]
Abstract
In earlier studies, we found that permeabilization of mammalian cells with nsPEF was accompanied by prolonged inhibition of voltage-gated (VG) currents through the plasma membrane. This study explored if the inhibition of VG Na(+) current (I(Na)) resulted from (i) reduction of the transmembrane Na(+) gradient due to its influx via nsPEF-opened pores, and/or (ii) downregulation of the VG channels by a Ca(2+)-dependent mechanism. We found that a single 300 ns electric pulse at 1.6-5.3 kV/cm triggered sustained Na(+) influx in exposed NG108 cells and in primary chromaffin cells, as detected by increased fluorescence of a Sodium Green Dye. In the whole-cell patch clamp configuration, this influx was efficiently buffered by the pipette solution so that the increase in the intracellular concentration of Na(+) ([Na](i)) did not exceed 2-3 mM. [Na](i) increased uniformly over the cell volume and showed no additional peaks immediately below the plasma membrane. Concurrently, nsPEF reduced VG I(Na) by 30-60% (at 4 and 5.3 kV/cm). In control experiments, even a greater increase of the pipette [Na(+)] (by 5 mM) did not attenuate VG I(Na), thereby indicating that the nsPEF-induced Na(+) influx was not the cause of VG I(Na) inhibition. Similarly, adding 20 mM of a fast Ca(2+) chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) into the pipette solution did not prevent or attenuate the inhibition of the VG I(Na) by nsPEF. These findings point to possible Ca(2+)-independent downregulation of the VG Na(+) channels (e.g., caused by alteration of the lipid bilayer) or the direct effect of nsPEF on the channel.
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Affiliation(s)
- Vasyl Nesin
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA
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45
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Abstract
Phosphoinositides, especially phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] are required for the activity of many different ion channels. This chapter will highlight various aspects of this paradigm, by discussing current knowledge on four different ion channel families: inwardly rectifying K(+) (Kir) channels, KCNQ voltage gated K(+) channels, voltage gated Ca(2+) (VGCC) channels and Transient Receptor Potential (TRP) channels. Our main focus is to discuss functional aspects of this regulation, i.e. how changes in the concentration of PtdIns(4,5)P(2) in the plasma membrane upon phospholipase C activation may modulate the activity of ion channels, and what are the major determinants of this regulation. We also discuss how channels act as coincidence detectors sensing phosphoinositide levels and other signalling molecules. We also briefly discuss the available methods to study phosphoinositide regulation of ion channels, and structural aspects of interaction of ion channel proteins with these phospholipids. Finally, in several cases the effect of PtdIns(4,5)P(2) is more complex than a simple dependence of ion channel activity on the lipid, and we will discuss some these complexities.
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Affiliation(s)
- Nikita Gamper
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT, Leeds, UK,
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Abstract
Voltage-gated M-type (KCNQ) K+ channels play critical roles in regulation of neuronal excitability. Previous work showed A-kinase-anchoring protein (AKAP)79/150-mediated protein kinase C (PKC) phosphorylation of M channels to be involved in M current (I(M)) suppression by muscarinic M1, but not bradykinin B2, receptors. In this study, we first explored whether purinergic and angiotensin suppression of I(M) in superior cervical ganglion (SCG) sympathetic neurons involves AKAP79/150. Transfection into rat SCG neurons of ΔA-AKAP79, which lacks the A domain necessary for PKC binding, or the absence of AKAP150 in AKAP150(-/-) mice, did not affect I(M) suppression by purinergic agonist or by bradykinin, but reduced I(M) suppression by muscarinic agonist and angiotensin II. Transfection of AKAP79, but not ΔA-AKAP79 or AKAP15, rescued suppression of I(M) by muscarinic receptors in AKAP150(-/-) neurons. We also tested association of AKAP79 with M(1), B(2), P2Y(6), and AT(1) receptors, and KCNQ2 and KCNQ3 channels, via Förster resonance energy transfer (FRET) on Chinese hamster ovary cells under total internal refection fluorescence microscopy, which revealed substantial FRET between AKAP79 and M1 or AT1 receptors, and with the channels, but only weak FRET with P2Y(6) or B2 receptors. The involvement of AKAP79/150 in G(q/11)-coupled muscarinic regulation of N- and L-type Ca2+) channels and by cAMP/protein kinase A was also studied. We found AKAP79/150 to not play a role in the former, but to be necessary for forskolin-induced upregulation of L-current. Thus, AKAP79/150 action correlates with the PIP(2) (phosphatidylinositol 4,5-bisphosphate)-depletion mode of I(M) suppression, but does not generalize to G(q/11)-mediated inhibition of N- or L-type Ca2+ channels.
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47
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Kukkonen JP. A ménage à trois made in heaven: G-protein-coupled receptors, lipids and TRP channels. Cell Calcium 2011; 50:9-26. [DOI: 10.1016/j.ceca.2011.04.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 04/21/2011] [Accepted: 04/22/2011] [Indexed: 12/15/2022]
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48
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Mackrill JJ. Oxysterols and calcium signal transduction. Chem Phys Lipids 2011; 164:488-95. [PMID: 21513705 DOI: 10.1016/j.chemphyslip.2011.04.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 04/04/2011] [Accepted: 04/06/2011] [Indexed: 12/31/2022]
Abstract
Ionised calcium (Ca(2+)) is a key second messenger, regulating almost every cellular process from cell death to muscle contraction. Cytosolic levels of this ion can be increased via gating of channel proteins located in the plasma membrane, endoplasmic reticulum and other membrane-delimited organelles. Ca(2+) can be removed from cells by extrusion across the plasma membrane, uptake into organelles and buffering by anionic components. Ca(2+) channels and extrusion mechanisms work in concert to generate diverse spatiotemporal patterns of this second messenger, the distinct profiles of which determine different cellular outcomes. Increases in cytoplasmic Ca(2+) concentration are one of the most rapid cellular responses upon exposure to certain oxysterol congeners or to oxidised low-density lipoprotein, occurring within seconds of addition and preceding increases in levels of reactive oxygen species, or changes in gene expression. Furthermore, exposure of cells to oxysterols for periods of hours to days modulates Ca(2+) signal transduction, with these longer-term alterations in cellular Ca(2+) homeostasis potentially underlying pathological events within atherosclerotic lesions, such as hyporeactivity to vasoconstrictors observed in vascular smooth muscle, or ER stress-induced cell death in macrophages. Despite their candidate roles in physiology and disease, little is known about the molecular mechanisms that couple changes in oxysterol concentrations to alterations in Ca(2+) signalling. This review examines the ways in which oxysterols could influence Ca(2+) signal transduction and the potential roles of this in health and disease.
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Affiliation(s)
- John J Mackrill
- Department of Physiology, University College Cork, Cork, Ireland.
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49
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Silswal N, Parelkar NK, Wacker MJ, Brotto M, Andresen J. Phosphatidylinositol 3,5-bisphosphate increases intracellular free Ca2+ in arterial smooth muscle cells and elicits vasocontraction. Am J Physiol Heart Circ Physiol 2011; 300:H2016-26. [PMID: 21421826 DOI: 10.1152/ajpheart.01011.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Phosphoinositide (3,5)-bisphosphate [PI(3,5)P(2)] is a newly identified phosphoinositide that modulates intracellular Ca(2+) by activating ryanodine receptors (RyRs). Since the contractile state of arterial smooth muscle depends on the concentration of intracellular Ca(2+), we hypothesized that by mobilizing sarcoplasmic reticulum (SR) Ca(2+) stores PI(3,5)P(2) would increase intracellular Ca(2+) in arterial smooth muscle cells and cause vasocontraction. Using immunohistochemistry, we found that PI(3,5)P(2) was present in the mouse aorta and that exogenously applied PI(3,5)P(2) readily entered aortic smooth muscle cells. In isolated aortic smooth muscle cells, exogenous PI(3,5)P(2) elevated intracellular Ca(2+), and it also contracted aortic rings. Both the rise in intracellular Ca(2+) and the contraction caused by PI(3,5)P(2) were prevented by antagonizing RyRs, while the majority of the PI(3,5)P(2) response was intact after blockade of inositol (1,4,5)-trisphosphate receptors. Depletion of SR Ca(2+) stores with thapsigargin or caffeine and/or ryanodine blunted the Ca(2+) response and greatly attenuated the contraction elicited by PI(3,5)P(2). The removal of extracellular Ca(2+) or addition of verapamil to inhibit voltage-dependent Ca(2+) channels reduced but did not eliminate the Ca(2+) or contractile responses to PI(3,5)P(2). We also found that PI(3,5)P(2) depolarized aortic smooth muscle cells and that LaCl(3) inhibited those aspects of the PI(3,5)P(2) response attributable to extracellular Ca(2+). Thus, full and sustained aortic contractions to PI(3,5)P(2) required the release of SR Ca(2+), probably via the activation of RyR, and also extracellular Ca(2+) entry via voltage-dependent Ca(2+) channels.
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Affiliation(s)
- Neerupma Silswal
- Basic Medical Science Dept., Muscle Biology Research Group, School of Medicine, Univ. of Missouri, Kansas City, MO 64108, USA
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50
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Zaika O, Zhang J, Shapiro MS. Combined phosphoinositide and Ca2+ signals mediating receptor specificity toward neuronal Ca2+ channels. J Biol Chem 2011; 286:830-41. [PMID: 21051544 PMCID: PMC3013042 DOI: 10.1074/jbc.m110.166033] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 10/08/2010] [Indexed: 01/17/2023] Open
Abstract
Phosphatidylinositol 4,5-bisphosphate (PIP(2)) regulates Ca(2+) (I(Ca)) and M-type K(+) currents in superior cervical ganglion sympathetic neurons. In those cells, M(1) muscarinic and AT(1) angiotensin types do not elicit Ca(2+)(i) signals and suppress both currents via depletion of PIP(2), whereas the B(2) bradykinin and P2Y purinergic types elicit robust IP(3)-mediated [Ca(2+)](i) rises and neither deplete PIP(2) nor inhibit I(Ca). We have suggested that this specificity arises from differential Ca(2+)(i) signals underlying receptor-specific stimulation of PIP(2) synthesis by phosphatidylinositol (PI) 4-kinase. Here, we investigate which PI 4-kinase isoform underlies this signal, whether stimulation of PI 4-phosphate 5-kinase is also required, and the origin of receptor-specific Ca(2+)(i) signals. Recordings of I(Ca) were used as a PIP(2) "biosensor." In control, stimulation of M(1), but not B(2) or P2Y, receptors robustly suppressed I(Ca). However, when PI 4-kinase IIIβ, diacylglycerol kinase, Rho, or Rho-kinase was blocked, agonists of all three receptors robustly suppressed I(Ca). Overexpression of exogenous M(1) receptors yielded large [Ca(2+)](i) rises by muscarinic agonist, and transfection of wild-type IRBIT decreased Ca(2+)(i) signals, whereas dominant negative IRBIT-S68A had little effect on B(2) or P2Y responses but greatly increased muscarinic responses. We conclude that overlaid on microdomain organization is IRBIT, setting a "threshold" for [IP(3)], assisting in fidelity of receptor specificity.
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Affiliation(s)
- Oleg Zaika
- From the Department of Physiology, University of Texas Health Science Center, San Antonio, Texas 78229
| | - Jie Zhang
- From the Department of Physiology, University of Texas Health Science Center, San Antonio, Texas 78229
| | - Mark S. Shapiro
- From the Department of Physiology, University of Texas Health Science Center, San Antonio, Texas 78229
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