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Silnitsky S, Rubin SJS, Zerihun M, Qvit N. An Update on Protein Kinases as Therapeutic Targets-Part I: Protein Kinase C Activation and Its Role in Cancer and Cardiovascular Diseases. Int J Mol Sci 2023; 24:17600. [PMID: 38139428 PMCID: PMC10743896 DOI: 10.3390/ijms242417600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/10/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
Protein kinases are one of the most significant drug targets in the human proteome, historically harnessed for the treatment of cancer, cardiovascular disease, and a growing number of other conditions, including autoimmune and inflammatory processes. Since the approval of the first kinase inhibitors in the late 1990s and early 2000s, the field has grown exponentially, comprising 98 approved therapeutics to date, 37 of which were approved between 2016 and 2021. While many of these small-molecule protein kinase inhibitors that interact orthosterically with the protein kinase ATP binding pocket have been massively successful for oncological indications, their poor selectively for protein kinase isozymes have limited them due to toxicities in their application to other disease spaces. Thus, recent attention has turned to the use of alternative allosteric binding mechanisms and improved drug platforms such as modified peptides to design protein kinase modulators with enhanced selectivity and other pharmacological properties. Herein we review the role of different protein kinase C (PKC) isoforms in cancer and cardiovascular disease, with particular attention to PKC-family inhibitors. We discuss translational examples and carefully consider the advantages and limitations of each compound (Part I). We also discuss the recent advances in the field of protein kinase modulators, leverage molecular docking to model inhibitor-kinase interactions, and propose mechanisms of action that will aid in the design of next-generation protein kinase modulators (Part II).
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Affiliation(s)
- Shmuel Silnitsky
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Henrietta Szold St. 8, Safed 1311502, Israel; (S.S.); (M.Z.)
| | - Samuel J. S. Rubin
- Department of Medicine, School of Medicine, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA;
| | - Mulate Zerihun
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Henrietta Szold St. 8, Safed 1311502, Israel; (S.S.); (M.Z.)
| | - Nir Qvit
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Henrietta Szold St. 8, Safed 1311502, Israel; (S.S.); (M.Z.)
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Jimenez-Blasco D, Santofimia-Castaño P, Gonzalez A, Almeida A, Bolaños JP. Astrocyte NMDA receptors' activity sustains neuronal survival through a Cdk5-Nrf2 pathway. Cell Death Differ 2015; 22:1877-89. [PMID: 25909891 DOI: 10.1038/cdd.2015.49] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 03/07/2015] [Accepted: 03/23/2015] [Indexed: 12/16/2022] Open
Abstract
Neurotransmission unavoidably increases mitochondrial reactive oxygen species. However, the intrinsic antioxidant defense of neurons is weak and hence the mechanism whereby these cells are physiologically protected against oxidative damage is unknown. Here we found that the antioxidant defense of neurons is repressed owing to the continuous protein destabilization of the master antioxidant transcriptional activator, nuclear factor-erythroid 2-related factor-2 (Nrf2). By contrast, Nrf2 is highly stable in neighbor astrocytes explaining their robust antioxidant defense and resistance against oxidative stress. We also show that subtle and persistent stimulation of N-methyl-d-aspartate receptors (NMDAR) in astrocytes, through a mechanism not requiring extracellular Ca²⁺ influx, upregulates a signal transduction pathway involving phospholipase C-mediated endoplasmic reticulum release of Ca²⁺ and protein kinase Cδ activation. Active protein kinase Cδ promotes, by phosphorylation, the stabilization of p35, a cyclin-dependent kinase-5 (Cdk5) cofactor. Active p35/Cdk5 complex in the cytosol phosphorylates Nrf2 at Thr(395), Ser(433) and Thr(439) that is sufficient to promote Nrf2 translocation to the nucleus and induce the expression of antioxidant genes. Furthermore, this Cdk5-Nrf2 transduction pathway boosts glutathione metabolism in astrocytes efficiently protecting closely spaced neurons against oxidative damage. Thus, intercellular communication through NMDAR couples neurotransmission with neuronal survival.
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Affiliation(s)
- D Jimenez-Blasco
- Institute of Functional Biology and Genomics (IBFG), University of Salamanca-CSIC, 37007 Salamanca, Spain.,Institute of Biomedical Research of Salamanca (IBSAL), University Hospital of Salamanca, 37007 Salamanca, Spain
| | - P Santofimia-Castaño
- Department of Physiology, Faculty of Veterinary, University of Extremadura, 10003 Caceres, Spain
| | - A Gonzalez
- Department of Physiology, Faculty of Veterinary, University of Extremadura, 10003 Caceres, Spain
| | - A Almeida
- Institute of Functional Biology and Genomics (IBFG), University of Salamanca-CSIC, 37007 Salamanca, Spain.,Institute of Biomedical Research of Salamanca (IBSAL), University Hospital of Salamanca, 37007 Salamanca, Spain
| | - J P Bolaños
- Institute of Functional Biology and Genomics (IBFG), University of Salamanca-CSIC, 37007 Salamanca, Spain.,Institute of Biomedical Research of Salamanca (IBSAL), University Hospital of Salamanca, 37007 Salamanca, Spain
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Does modulation of spinal N-methyl-D-aspartic acid receptor by pre-activation accelerate the development of morphine tolerance? Med Hypotheses 2014; 84:91-3. [PMID: 25550113 DOI: 10.1016/j.mehy.2014.12.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 11/25/2014] [Accepted: 12/14/2014] [Indexed: 01/05/2023]
Abstract
Repeated morphine administration usually leads to a number of neuroadaptive processes, including tolerance and sensitization. However, research has shown that the induction and maintenance of central sensitization is dependent on N-methyl-d-aspartic acid receptor (NMDAR) activation. Chronic morphine exposure has been shown to result in spinal sensitization and activation of spinal NMDARs. Chronic morphine treatment and the activation of spinal NMDARs may be synergistic and form a closed loop that may worsen the development of morphine analgesic tolerance and spinal sensitization. Inhibition of NMDARs with an antagonist could effectively alleviate the development of morphine analgesic tolerance. So, what is the effect of modulating spinal NMDAR activation with exogenous agonists or neuropathic input on the development of morphine-induced analgesic tolerance? Our hypothesis is that chronic morphine treatment may worsen the already activation of spinal NMDARs and spinal sensitization after agonist application or neuropathic input to shorten the process of morphine-induced analgesic tolerance.
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Zhang HM, Su Q. PKC in developmental hypothyroid rat brain. Neurol Sci 2014; 35:1161-6. [PMID: 24682728 DOI: 10.1007/s10072-014-1716-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 03/10/2014] [Indexed: 12/13/2022]
Abstract
Thyroid hormone (TH) is essential for the proper development of mammalian central nervous system. TH deficiency during the critical period of brain development results in permanent cognitive and neurological impairments. Members of the protein kinase C (PKC) family play a key role in the regulation of cellular functions in the nervous system. Alteration of PKC can be involved in the pathogenesis of neuronal disorders. This review details recent progress made in determining the roles played by PKC isoforms in developing hypothyroid rat brain. Evidence indicates that hippocampus down-regulation of PKCβ and PKCγ may be related to impaired learning and memory observed in perinatal hypothyroid rats. Enhanced PKCα activity in neonatal hypothyroid brain may bring about oxidative stress and cause brain damage. The activated pro-apoptotic PKCs including PKCδ can cause extensive apoptosis in the hypothyroid rat brain.
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Affiliation(s)
- Hong-Mei Zhang
- Department of Endocrinology, Xin Hua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200092, People's Republic of China
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Zhang HM, Lin N, Dong Y, Su Q, Luo M. Protein kinase Cα is involved in impaired perinatal hypothyroid rat brain development. J Neurosci Res 2012; 91:211-9. [PMID: 23152155 DOI: 10.1002/jnr.23125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 06/28/2012] [Accepted: 07/13/2012] [Indexed: 11/07/2022]
Abstract
Protein kinase Cα (PKCα) has been implicated in the regulation of a variety of cellular functions, such as proliferation, differentiation, and apoptosis, in response to a diverse range of stimuli. Activated PKCα mediates oxidative stress, apoptosis, and inflammatory reaction. Thyroid hormone (TH) is essential for the proper development of the mammalian central nervous system. TH deficiency during critical periods of brain development results in permanent cognitive and neurological impairments. In the present study, we attempted to explore whether PKCα is involved in impaired brain function in developing hypothyroid rat brain. Severe perinatal hypothyroidism was obtained by administration of 30 mg/day propylthiouracil to dams. Brain PKC activity in hypothyroid pups was increased significantly in cytosol and membrane fractions. The change of membrane PKC activity was more marked than that of cytosol, and hypothyroidism led to a higher ratio of membrane PKC activity to that in cytosol, which means abnormal activation of PKC in developing hypothyroid rat brain. Thyroxine replacement partially corrected these changes. After being treated with bisindolmaleimide XI, a mainly selective inhibitor for PKCα, the hypothyroid pups showed improved place navigation test results, and further Western blot analysis showed that PKCα expression in cytosol fractions was increased in hypothyroid rat brain with or without bisindolmaleimide XI treatment, but, after treatment with bisindolmaleimide XI, PKCα content in membrane fractions decreased almost to normal. Therefore, we conclude that PKCα appears to be involved in the impaired brain development observed in perinatal hypothyroid rat brain.
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Affiliation(s)
- Hong-Mei Zhang
- Department of Endocrinology, Xin Hua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China
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Control of intracellular calcium signaling as a neuroprotective strategy. Molecules 2010; 15:1168-95. [PMID: 20335972 PMCID: PMC2847496 DOI: 10.3390/molecules15031168] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Revised: 02/05/2010] [Accepted: 03/02/2010] [Indexed: 12/13/2022] Open
Abstract
Both acute and chronic degenerative diseases of the nervous system reduce the viability and function of neurons through changes in intracellular calcium signaling. In particular, pathological increases in the intracellular calcium concentration promote such pathogenesis. Disease involvement of numerous regulators of intracellular calcium signaling located on the plasma membrane and intracellular organelles has been documented. Diverse groups of chemical compounds targeting ion channels, G-protein coupled receptors, pumps and enzymes have been identified as potential neuroprotectants. The present review summarizes the discovery, mechanisms and biological activity of neuroprotective molecules targeting proteins that control intracellular calcium signaling to preserve or restore structure and function of the nervous system. Disease relevance, clinical applications and new technologies for the identification of such molecules are being discussed.
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Sun MK, Alkon DL. Protein kinase C activators as synaptogenic and memory therapeutics. Arch Pharm (Weinheim) 2010; 342:689-98. [PMID: 19899099 DOI: 10.1002/ardp.200900050] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The last decade has witnessed a rapid progress in understanding of the molecular cascades that may underlie memory and memory disorders. Among the critical players, activity of protein kinase C (PKC) isoforms is essential for many types of learning and memory and their dysfunction, and is critical in memory disorders. PKC inhibition and functional deficits lead to an impairment of various types of learning and memory, consistent with the observations that neurotoxic amyloid inhibits PKC activity and that transgenic animal models with PKCbeta deficit exhibit impaired capacity in cognition. In addition, PKC isozymes play a regulatory role in amyloid production and accumulation. Restoration of the impaired PKC signal pathway pharmacologically results in an enhanced memory capacity and synaptic remodeling / repair and synaptogenesis, and, therefore, represents a potentially important strategy for the treatment of memory disorders, including Alzheimer's dementia. The PKC activators, especially those that are isozyme-specific, are a new class of drug candidates that may be developed as future memory therapeutics.
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Affiliation(s)
- Miao-Kun Sun
- Blanchette Rockefeller Neurosciences Institute, Rockville, MD 20850, USA.
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Butcher AJ, Torrecilla I, Young KW, Kong KC, Mistry SC, Bottrill AR, Tobin AB. N-methyl-D-aspartate receptors mediate the phosphorylation and desensitization of muscarinic receptors in cerebellar granule neurons. J Biol Chem 2009; 284:17147-17156. [PMID: 19332541 PMCID: PMC2719353 DOI: 10.1074/jbc.m901031200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Changes in synaptic strength mediated by ionotropic glutamate N-methyl-d-asparate (NMDA) receptors is generally considered to be the molecular mechanism underlying memory and learning. NMDA receptors themselves are subject to regulation through signaling pathways that are activated by G-protein-coupled receptors (GPCRs). In this study we investigate the ability of NMDA receptors to regulate the signaling of GPCRs by focusing on the Gq/11-coupled M3-muscarinic receptor expressed endogenously in mouse cerebellar granule neurons. We show that NMDA receptor activation results in the phosphorylation and desensitization of M3-muscarinic receptors through a mechanism dependent on NMDA-mediated calcium influx and the activity of calcium-calmodulin-dependent protein kinase II. Our study reveals a complex pattern of regulation where GPCRs (M3-muscarinic) and NMDA receptors can feedback on each other in a process that is likely to influence the threshold value of signaling networks involved in synaptic plasticity.
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Affiliation(s)
- Adrian J Butcher
- From the Department of Cell Physiology and Pharmacology, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Ignacio Torrecilla
- From the Department of Cell Physiology and Pharmacology, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Kenneth W Young
- Medical Research Council Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Kok Choi Kong
- From the Department of Cell Physiology and Pharmacology, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Sharad C Mistry
- Protein and Nucleic Acid Chemistry Laboratory, University of Leicester, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Andrew R Bottrill
- Protein and Nucleic Acid Chemistry Laboratory, University of Leicester, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Andrew B Tobin
- From the Department of Cell Physiology and Pharmacology, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, United Kingdom.
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Ring A, Tanso R. Measurements with fluorescent probes in primary neural cultures; improved multiwell techniques. J Pharmacol Toxicol Methods 2007; 56:300-7. [PMID: 17587604 DOI: 10.1016/j.vascn.2007.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Accepted: 05/18/2007] [Indexed: 11/22/2022]
Abstract
INTRODUCTION Fluorescence imaging techniques are valuable tools for the pharmacological characterization of CNS drugs. Dissected cerebellar granule neurons (CGN) are an important model system in the study of mechanisms of excitotoxicity, glutamate receptors and transporters. Widely applied techniques use fluorescent probes loaded in neural cells cultured on glass supports. CGN, however, require at least 7 days for differentiation and over time cells tend to cluster and loose adherence to the glass substrate. This problem is accentuated in small wells (e.g. 96-well plates). METHODS CGN were grown on large coverslips (60 x 24 mm) and measurements made with a designed mountable multiwell in 48 regions on 4 coverslips at a time. The UV ratiometric probe fura-2 was used to measure glutamatergic calcium ([Ca(2+)](i)) responses induced by NMDA. The IC(50) of NMDA receptor antagonists was determined from inhibition curves with 6 doses and 8 parallels per experiment. RESULTS The method was validated by comparing with published data for the dose response to NMDA and glycine and IC(50) values for ion-channel block by Mg(2+) and MK-801. DISCUSSION Resolution is enhanced with the new technique since it allows measurement of multiple doses on cells from the same batch. It has advantages to cuvette techniques because cells have intact dendritic tree and synaptic function and it is a convenient method to obtain reliable dose-response curves for NMDA channel modulators on differentiated neural cells.
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Affiliation(s)
- Avi Ring
- Department of Protection, Norwegian Defence Research Establishment, Kjeller, Norway.
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Willets JM, Nelson CP, Nahorski SR, Challiss RAJ. The regulation of M1 muscarinic acetylcholine receptor desensitization by synaptic activity in cultured hippocampal neurons. J Neurochem 2007; 103:2268-80. [PMID: 17908240 PMCID: PMC2658029 DOI: 10.1111/j.1471-4159.2007.04931.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
To better understand metabotropic/ionotropic integration in neurons we have examined the regulation of M1 muscarinic acetylcholine (mACh) receptor signalling in mature (> 14 days in vitro), synaptically-active hippocampal neurons in culture. Using a protocol where neurons are exposed to an EC(50) concentration of the muscarinic agonist methacholine (MCh) prior to (R1), and following (R2) a desensitizing pulse of a high concentration of this agonist, we have found that the reduction in M(1) mACh receptor responsiveness is decreased in quiescent (+tetrodotoxin) neurons and increased when synaptic activity is enhanced by blocking GABA(A) receptors with picrotoxin. The picrotoxin-mediated effect on M1 mACh receptor responsiveness was completely prevented by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor blockade. Inhibition of endogenous G protein-coupled receptor kinase 2 by transfection with the non-G(q/11)alpha-binding, catalytically-inactive (D110A,K220R)G protein-coupled receptor kinase 2 mutant, decreased the extent of M1 mACh receptor desensitization under all conditions. Pharmacological inhibition of protein kinase C (PKC) activity, or chronic phorbol ester-induced PKC down-regulation had no effect on agonist-mediated receptor desensitization in quiescent or spontaneously synaptically active neurons, but significantly decreased the extent of receptor desensitization in picrotoxin-treated neurons. MCh stimulated the translocation of diacylglycerol- sensitive eGFP-PKCepsilon, but not Ca2+/diacylglycerol-sensitive eGFP-PKCbetaII in both the absence, and presence of tetrodotoxin. Under these conditions, MCh-stimulated eGFP-myristoylated, alanine-rich C kinase substrate translocation was dependent on PKC activity, but not Ca2+/calmodulin. In contrast, picrotoxin-driven translocation of myristoylated, alanine-rich C kinase substrate was accompanied by translocation of PKCbetaII, but not PKCepsilon, and was dependent on PKC and Ca2+/calmodulin. Taken together these data suggest that the level of synaptic activity may determine the different kinases recruited to regulate M1 mACh receptor desensitization in neurons.
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Affiliation(s)
- Jonathon M Willets
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, UK
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Billups D, Billups B, Challiss RAJ, Nahorski SR. Modulation of Gq-protein-coupled inositol trisphosphate and Ca2+ signaling by the membrane potential. J Neurosci 2006; 26:9983-95. [PMID: 17005862 PMCID: PMC2266565 DOI: 10.1523/jneurosci.2773-06.2006] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Gq-protein-coupled receptors (GqPCRs) are widely distributed in the CNS and play fundamental roles in a variety of neuronal processes. Their activation results in phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis and Ca2+ release from intracellular stores via the phospholipase C (PLC)-inositol 1,4,5-trisphosphate (IP3) signaling pathway. Because early GqPCR signaling events occur at the plasma membrane of neurons, they might be influenced by changes in membrane potential. In this study, we use combined patch-clamp and imaging methods to investigate whether membrane potential changes can modulate GqPCR signaling in neurons. Our results demonstrate that GqPCR signaling in the human neuronal cell line SH-SY5Y and in rat cerebellar granule neurons is directly sensitive to changes in membrane potential, even in the absence of extracellular Ca2+. Depolarization has a bidirectional effect on GqPCR signaling, potentiating thapsigargin-sensitive Ca2+ responses to muscarinic receptor activation but attenuating those mediated by bradykinin receptors. The depolarization-evoked potentiation of the muscarinic signaling is graded, bipolar, non-inactivating, and with no apparent upper limit, ruling out traditional voltage-gated ion channels as the primary voltage sensors. Flash photolysis of caged IP3/GPIP2 (glycerophosphoryl-myo-inositol 4,5-bisphosphate) places the voltage sensor before the level of the Ca2+ store, and measurements using the fluorescent bioprobe eGFP-PH(PLCdelta) (enhanced green fluorescent protein-pleckstrin homology domain-PLCdelta) directly demonstrate that voltage affects muscarinic signaling at the level of the IP3 production pathway. The sensitivity of GqPCR IP3 signaling in neurons to voltage itself may represent a fundamental mechanism by which ionotropic signals can shape metabotropic receptor activity in neurons and influence processes such as synaptic plasticity in which the detection of coincident signals is crucial.
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Affiliation(s)
- Daniela Billups
- Department of Cell Physiology and Pharmacology, Medical Sciences Building, University of Leicester, Leicester LE1 9HN, United Kingdom.
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Hisatsune C, Kuroda Y, Akagi T, Torashima T, Hirai H, Hashikawa T, Inoue T, Mikoshiba K. Inositol 1,4,5-trisphosphate receptor type 1 in granule cells, not in Purkinje cells, regulates the dendritic morphology of Purkinje cells through brain-derived neurotrophic factor production. J Neurosci 2006; 26:10916-24. [PMID: 17050730 PMCID: PMC6674761 DOI: 10.1523/jneurosci.3269-06.2006] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Here, we show that cultured Purkinje cells from inositol 1,4,5-trisphosphate receptor type 1 knock-out (IP3R1KO) mice exhibited abnormal dendritic morphology. Interestingly, despite the huge amount of IP3R1 expression in Purkinje cells, IP3R1 in granule cells, not in the Purkinje cells, was responsible for the shape of Purkinje cell dendrites. We also found that BDNF application rescued the dendritic abnormality of IP3R1KO Purkinje cells, and that the increase in BDNF expression in response to activation of AMPA receptor (AMPAR) and metabotropic glutamate receptor (mGluR) was impaired in IP3R1KO cerebellar granule cells. In addition, we observed abnormalities in the dendritic morphology of Purkinje cells and in the ultrastructure of parallel fiber-Purkinje cell (PF-PC) synapses in IP3R1KO mice in vivo. We concluded that activation of AMPAR and mGluR increases BDNF expression through IP3R1-mediated signaling in cerebellar granule cells, which contributes to the dendritic outgrowth of Purkinje cells intercellularly, possibly by modifying PF-PC synaptic efficacy.
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Affiliation(s)
- Chihiro Hisatsune
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako City, Saitama 351-0198, Japan.
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Origlia N, Kuczewski N, Aztiria E, Gautam D, Wess J, Domenici L. Muscarinic acetylcholine receptor knockout mice show distinct synaptic plasticity impairments in the visual cortex. J Physiol 2006; 577:829-40. [PMID: 17023506 PMCID: PMC1890385 DOI: 10.1113/jphysiol.2006.117119] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In the present report, we focused our attention on the role played by the muscarinic acetylcholine receptors (mAChRs) in different forms of long-term synaptic plasticity. Specifically, we investigated long-term potentiation (LTP) and long-term depression (LTD) expression elicited by theta-burst stimulation (TBS) and low-frequency stimulation (LFS), respectively, in visual cortical slices obtained from different mAChR knockout (KO) mice. A normal LTP was evoked in M(1)/M(3) double KO mice, while LTP was impaired in the M(2)/M(4) double KO animals. On the other hand, LFS induced LTD in M(2)/M(4) double KO mice, but failed to do so in M(1)/M(3) KO mice. Interestingly, LFS produced LTP instead of LTD in M(1)/M(3) KO mice. Analysis of mAChR single KO mice revealed that LTP was affected only by the simultaneous absence of both M(2) and M(4) receptors. A LFS-dependent shift from LTD to LTP was also observed in slices from M(1) KO mice, while LTD was simply abolished in slices from M(3) KO mice. Using pharmacological tools, we showed that LTP in control mice was blocked by pertussis toxin, an inhibitor of G(i/o) proteins, but not by raising intracellular cAMP levels. In addition, the inhibition of phospholipase C by U73122 induced the same shift from LTD to LTP after LFS observed in M(1) single KO and M(1)/M(3) double KO mice. Our results indicate that different mAChR subtypes regulate different forms of long-term synaptic plasticity in the mouse visual cortex, activating specific G proteins and downstream intracellular mechanisms.
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Young KW, Billups D, Nelson CP, Johnston N, Willets JM, Schell MJ, Challiss RAJ, Nahorski SR. Muscarinic acetylcholine receptor activation enhances hippocampal neuron excitability and potentiates synaptically evoked Ca(2+) signals via phosphatidylinositol 4,5-bisphosphate depletion. Mol Cell Neurosci 2005; 30:48-57. [PMID: 15996483 DOI: 10.1016/j.mcn.2005.05.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Revised: 05/18/2005] [Accepted: 05/24/2005] [Indexed: 11/20/2022] Open
Abstract
Using single cell Ca(2+) imaging and whole cell current clamp recordings, this study aimed to identify the signal transduction mechanisms involved in mACh receptor-mediated, enhanced synaptic signaling in primary cultures of hippocampal neurons. Activation of M(1) mACh receptors produced a 2.48 +/- 0.26-fold enhancement of Ca(2+) transients arising from spontaneous synaptic activity in hippocampal neurons. Combined imaging of spontaneous Ca(2+) signals with inositol 1,4,5-trisphosphate (IP(3)) production in single neurons demonstrated that the methacholine (MCh)-mediated enhancement required activated G(q/11)alpha subunits and phospholipase C activity but did not require measurable increases in IP(3). Electrophysiological studies demonstrated that MCh treatment depolarized neurons from -64 +/- 3 to -45 +/- 3 mV and increased action potential generation. Depletion of plasma membrane phosphatidylinositol 4,5-bisphosphate (PIP(2)) enhanced neuronal excitability and prolonged the action of MCh. These studies suggest that, in addition to producing the second messengers IP(3) and diacylglycerol, mACh receptor activation may directly utilize PIP(2) hydrolysis to regulate neuronal excitability.
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Affiliation(s)
- Kenneth W Young
- Department of Cell Physiology and Pharmacology, Medical Sciences Building, University of Leicester, University Road, Leicester, LE1 9HN, UK.
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Jiang SX, Lertvorachon J, Hou ST, Konishi Y, Webster J, Mealing G, Brunette E, Tauskela J, Preston E. Chlortetracycline and Demeclocycline Inhibit Calpains and Protect Mouse Neurons against Glutamate Toxicity and Cerebral Ischemia. J Biol Chem 2005; 280:33811-8. [PMID: 16091365 DOI: 10.1074/jbc.m503113200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Minocycline is a potent neuroprotective tetracycline in animal models of cerebral ischemia. We examined the protective properties of chlortetracycline (CTC) and demeclocycline (DMC) and showed that these two tetracyclines were also potent neuroprotective against glutamate-induced neuronal death in vitro and cerebral ischemia in vivo. However, CTC and DMC appeared to confer neuroprotection through a unique mechanism compared with minocycline. Rather than inhibiting microglial activation and caspase, CTC and DMC suppressed calpain activities. In addition, CTC and DMC only weakly antagonized N-methyl-D-aspartate (NMDA) receptor activities causing 16 and 14%, respectively, inhibition of NMDA-induced whole cell currents and partially blocked NMDA-induced Ca2+ influx, commonly regarded as the major trigger of neuronal death. In vitro and in vivo experiments demonstrated that the two compounds selectively inhibited the activities of calpain I and II activated following glutamate treatment and cerebral ischemia. In contrast, minocycline did not significantly inhibit calpain activity. Taken together, these results suggested that CTC and DMC provide neuroprotection through suppression of a rise in intracellular Ca2+ and inhibition of calpains.
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Affiliation(s)
- Susan X Jiang
- Neurophysiology Group, National Research Council Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario K1A 0R6, Canada
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16
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Sun MK, Alkon DL. Protein kinase C substrate activators: potential as novel antidepressants. Drug Dev Res 2005. [DOI: 10.1002/ddr.20019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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17
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Bartlett PJ, Young KW, Nahorski SR, Challiss RAJ. Single Cell Analysis and Temporal Profiling of Agonist-mediated Inositol 1,4,5-Trisphosphate, Ca2+, Diacylglycerol, and Protein Kinase C Signaling using Fluorescent Biosensors. J Biol Chem 2005; 280:21837-46. [PMID: 15788407 DOI: 10.1074/jbc.m411843200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The magnitude and temporal nature of intracellular signaling cascades can now be visualized directly in single cells by the use of protein domains tagged with enhanced green fluorescent protein (eGFP). In this study, signaling downstream of G protein-coupled receptor-mediated phospholipase C (PLC) activation has been investigated in a cell line coexpressing recombinant M(3) muscarinic acetylcholine and alpha(1B) -adrenergic receptors. Confocal measurements of changes in inositol 1,4,5-trisphosphate (Ins(1,4,5)P(3)), using the pleckstrin homology domain of PLCdelta1 tagged to eGFP (eGFP-PH(PLCdelta)), and 1,2-diacylglycerol (DAG), using the C1 domain of protein kinase Cgamma (PKCgamma) (eGFP-C1(2)-PKCgamma), demonstrated clear translocation responses to methacholine and noradrenaline. Single cell EC(50) values calculated for each agonist indicated that responses to downstream signaling targets (Ca(2+) mobilization and PKC activation) were approximately 10-fold lower compared with respective Ins(1,4,5)P(3) and DAG EC(50) values. Examining the temporal profile of second messenger responses to sub-EC(50) concentrations of noradrenaline revealed oscillatory Ins(1,4,5)P(3), DAG, and Ca(2+) responses. Oscillatory recruitments of conventional (PKCbetaII) and novel (PKCepsilon) PKC isoenzymes were also observed which were synchronous with the Ca(2+) response measured simultaneously in the same cell. However, oscillatory PKC activity (as determined by translocation of eGFP-tagged myristoylated alanine-rich C kinase substrate protein) required oscillatory DAG production. We suggest a model that uses regenerative Ca(2+) release via Ins(1,4,5)P(3) receptors to initiate oscillatory second messenger production through a positive feedback effect on PLC. By acting on various components of the PLC signaling pathway the frequency-encoded Ca(2+) response is able to maintain signal specificity at a level downstream of PKC activation.
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Affiliation(s)
- Paula J Bartlett
- Department of Cell Physiology and Pharmacology, University of Leicester, Maurice Shock Medical Sciences Building, University Road, Leicester LE1 9HN, United Kingdom.
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18
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Downes CP, Gray A, Lucocq JM. Probing phosphoinositide functions in signaling and membrane trafficking. Trends Cell Biol 2005; 15:259-68. [PMID: 15866030 DOI: 10.1016/j.tcb.2005.03.008] [Citation(s) in RCA: 180] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The inositol phospholipids (PIs) comprise a family of eight species with different combinations of phosphate groups arranged around the inositol ring. PIs are among the most versatile signaling molecules known, with key roles in receptor-mediated signal transduction, actin remodeling and membrane trafficking. Recent studies have identified effector proteins and specific lipid-binding domains through which PIs signal. These lipid-binding domains can be used as probes to further our understanding of the spatial and temporal control of individual PI species. New layers of complexity revealed by the use of such probes include the occurrence of PIs at intracellular locations, the identification of phosphatidylinositol signaling hotspots and the presence of non-membrane pools of PIs in cell nuclei.
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Affiliation(s)
- C Peter Downes
- Division of Cell Signalling, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, UK.
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