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Houchat JN, Cartereau A, Taillebois E, Thany SH. Calmidazolium induces a decrease in nicotine-induced currents and intracellular calcium levels after pulse application of nicotine onto insect neurosecretory cells. JOURNAL OF INSECT PHYSIOLOGY 2022; 139:104385. [PMID: 35315336 DOI: 10.1016/j.jinsphys.2022.104385] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 03/01/2022] [Accepted: 03/16/2022] [Indexed: 06/14/2023]
Abstract
Dorsal unpaired median (DUM) neurons, are a class of insect neurosecretory cells, which are involved in the control of several functions, such as excretion and reproduction, or the release of neurohormones. Previous studies demonstrated that they express different nicotinic acetylcholine receptor subtypes, in particular α-bungarotoxin-insensitive receptors, with nAChR1 and nAChR2 subtypes. Here, we demonstrated that pulse application of 1 mM nicotine (300 ms pulse duration) induced inward currents which were reduced under bath application of 15 µM calmidazolium, a calmodulin inhibitor. Bath application of 0.5 µM α-bungarotoxin had no effect on calmidazolium action, suggesting that it could have an indirect effect through α-bungarotoxin-insensitive receptors. Indeed, nicotine-evoked currents were reduced by 10 µM d-tubocurarine, and completely blocked by 5 µM mecamylamine, which affected nAChR1 and nAChR2 subtypes, respectively. Our results demonstrated that nAChR2 subtypes are involved in the indirect effect of calmidazolium. Moreover, we found that this calmidazolium effect was associated to a strong reduction in intracellular calcium levels after pulse application of 1 mM nicotine. Thus, compared to previous studies on mammalian cells, calmidazolium did not cause an increase in intracellular calcium levels in DUM neurons, suggesting that different calcium mechanisms are involved in the calmidazolium effect.
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Affiliation(s)
- Jean-Noël Houchat
- Université d'Orléans, LBLGC USC-INRAE 1328, 1 rue de Chartres, Orléans 45067, France
| | - Alison Cartereau
- Université d'Orléans, LBLGC USC-INRAE 1328, 1 rue de Chartres, Orléans 45067, France
| | - Emiliane Taillebois
- Université d'Orléans, LBLGC USC-INRAE 1328, 1 rue de Chartres, Orléans 45067, France
| | - Steeve H Thany
- Université d'Orléans, LBLGC USC-INRAE 1328, 1 rue de Chartres, Orléans 45067, France.
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2
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Takla M, Huang CLH, Jeevaratnam K. The cardiac CaMKII-Na v1.5 relationship: From physiology to pathology. J Mol Cell Cardiol 2020; 139:190-200. [PMID: 31958466 DOI: 10.1016/j.yjmcc.2019.12.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 11/20/2019] [Accepted: 12/30/2019] [Indexed: 12/19/2022]
Abstract
The SCN5A gene encodes Nav1.5, which, as the cardiac voltage-gated Na+ channel's pore-forming α subunit, is crucial for the initiation and propagation of atrial and ventricular action potentials. The arrhythmogenic propensity of inherited SCN5A mutations implicates the Na+ channel in determining cardiomyocyte excitability under normal conditions. Cytosolic kinases have long been known to alter the kinetic profile of Nav1.5 inactivation via phosphorylation of specific residues. Recent substantiation of both the role of calmodulin-dependent kinase II (CaMKII) in modulating the properties of the Nav1.5 inactivation gate and the significant rise in oxidation-dependent autonomous CaMKII activity in structural heart disease has raised the possibility of a novel pathway for acquired arrhythmias - the CaMKII-Nav1.5 relationship. The aim of this review is to: (1) outline the relationship's translation from physiological adaptation to pathological vicious circle; and (2) discuss the relative merits of each of its components as pharmacological targets.
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Affiliation(s)
- Michael Takla
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom
| | - Christopher L-H Huang
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom; Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom; Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom.
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Analysis of the CaMKIIα and β splice-variant distribution among brain regions reveals isoform-specific differences in holoenzyme formation. Sci Rep 2018; 8:5448. [PMID: 29615706 PMCID: PMC5882894 DOI: 10.1038/s41598-018-23779-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 03/20/2018] [Indexed: 12/21/2022] Open
Abstract
Four CaMKII isoforms are encoded by distinct genes, and alternative splicing within the variable linker-region generates additional diversity. The α and β isoforms are largely brain-specific, where they mediate synaptic functions underlying learning, memory and cognition. Here, we determined the α and β splice-variant distribution among different mouse brain regions. Surprisingly, the nuclear variant αB was detected in all regions, and even dominated in hypothalamus and brain stem. For CaMKIIβ, the full-length variant dominated in most regions (with higher amounts of minor variants again seen in hypothalamus and brain stem). The mammalian but not fish CaMKIIβ gene lacks exon v3N that encodes the nuclear localization signal in αB, but contains three exons not found in the CaMKIIα gene (exons v1, v4, v5). While skipping of exons v1 and/or v5 generated the minor splice-variants β’, βe and βe’, essentially all transcripts contained exon v4. However, we instead detected another minor splice-variant (now termed βH), which lacks part of the hub domain that mediates formation of CaMKII holoenzymes. Surprisingly, in an optogenetic cellular assay of protein interactions, CaMKIIβH was impaired for binding to the β hub domain, but still bound CaMKIIα. This provides the first indication for isoform-specific differences in holoenzyme formation.
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4
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Taillebois E, Heuland E, Bourdin CM, Griveau A, Quinchard S, Tricoire-Leignel H, Legros C, Thany SH. Ca²⁺/calmodulin-dependent protein kinase II in the cockroach Periplaneta americana: identification of five isoforms and their tissues distribution. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2013; 83:138-150. [PMID: 23740573 DOI: 10.1002/arch.21102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) is a key kinase that transduces Ca²⁺ signals into downstream effects acting on a range of cellular processes in nervous system and muscular tissues. In insects, different CaMKII isoforms have been reported in Drosophila melanogaster, Apis florae, Bombus terrestris, and Bombus impatiens but little is known on the organization and tissue-specific expression of these isoforms with the exception of Drosophila. The present study reports the cloning of five CaMKII splice variants issued from a single gene and their tissue-specific expression in the cockroach Periplaneta americana. Each CaMKII isoform shared 82-90% identity with Drosophila CaMKII isoforms and accordingly were named PaCaMKII-A, PaCaMKII-B,PaCaMKII-C,PaCaMKII-D, and PaCaMKII-E. PaCaMKII-A and PaCaMKII-D isoforms are ubiquitously expressed in all tissues, but some such as PaCaMKII-B andPaCaMKII-C are preferentially expressed in the nerve cord and muscle. In addition, using single-cell reverse transcriptase-polymerase chain reaction (RT-PCR), we found a tissue-specific expression of PaCaMKII-E in the dorsal unpaired median neurons. Alternative splicing of PaCaMKII transcripts is likely a common mechanism in insects to control the pattern of isoform expression in the different tissues.
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Affiliation(s)
- Emiliane Taillebois
- Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM) UPRES EA 2647/USC INRA 1330, SFR QUASAV 4207, UFR Sciences, Université d'Angers, Angers, France
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5
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Ammar D, Nazari EM, Müller YMR, Allodi S. On the brain of a crustacean: a morphological analysis of CaMKII expression and its relation to sensory and motor pathways. PLoS One 2013; 8:e64855. [PMID: 23741406 PMCID: PMC3669419 DOI: 10.1371/journal.pone.0064855] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 04/19/2013] [Indexed: 12/13/2022] Open
Abstract
Calcium/calmodulin kinase II (CaMKII) is a Ca2+-activated enzyme that is abundant in vertebrate and invertebrate brains. However, its characterization is poorly addressed in the nervous system of crustaceans, and, to our knowledge, no studies have determined the microanatomical location of CaMKII in a crustacean species. In this study, we found labeling of CaMKII in the eyestalk and brain of the prawn Macrobrachium acanthurus, by means of immunohistochemistry and Western blotting. Antibodies against neuron (ß tubulin III), glutamate receptor (GluA1), and FMRFamide were used in order to further characterize the CaMKII-labeled cells in the brain. In the eyestalk, strong labeling with CaMKII was observed in the photoreceptors. These cells, especially in the rhabdom, were also reactive to anti-ß tubulin III, whereas the pigment cells were labeled with anti-CaMKII. GluA1 co-located with CaMKII in the photoreceptors. Also, CaMKII appeared in the same sites as FMRFamide in the deutocerebrum, including the olfactory lobe, and in the tritocerebrum, specifically in the antennular neuropil, indicating that the synaptic areas in these regions may be related to sensory-motor processing. In the brain, the identification of cells and regions that express CaMKII contributes to the understanding of the processing of neural connections and the modulating role of CaMKII in decapod crustaceans.
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Affiliation(s)
- Dib Ammar
- Programa de Pós-Graduação em Biologia Celular e do Desenvolvimento, Departamento de Biologia Celular, Embriologia e Genética, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Santa Catarina, Brazil
- Programa de Pós-Graduação em Morfologia, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Evelise M. Nazari
- Programa de Pós-Graduação em Biologia Celular e do Desenvolvimento, Departamento de Biologia Celular, Embriologia e Genética, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Santa Catarina, Brazil
- Programa de Pós-Graduação em Morfologia, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Yara M. R. Müller
- Programa de Pós-Graduação em Biologia Celular e do Desenvolvimento, Departamento de Biologia Celular, Embriologia e Genética, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Santa Catarina, Brazil
| | - Silvana Allodi
- Programa de Pós-Graduação em Morfologia, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Programa de Pós-Graduação em Ciências Biológicas - Fisiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail:
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Lohr C, Bergstein S, Hirnet D. Developmental distribution of CaM kinase II in the antennal lobe of the sphinx moth Manduca sexta. Cell Tissue Res 2006; 327:189-97. [PMID: 16896952 DOI: 10.1007/s00441-006-0249-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Accepted: 05/15/2006] [Indexed: 01/09/2023]
Abstract
The antennal lobe (primary olfactory center of insects) is completely reorganized during metamorphosis. This reorganization is accompanied by changing patterns of calcium signaling in neurons and glial cells. In the present study, we investigated the developmental distribution of a major calcium-dependent protein, viz., calcium/calmodulin-dependent protein kinase II (CaM kinase II), in the antennal lobe of the sphinx moth Manduca sexta by using a monoclonal antibody. During synaptogenesis (developmental stages 6-10), we found a redistribution of CaM kinase II immunoreactivity, from a homogeneous distribution in the immature neuropil to an accumulation in the neuropil of the glomeruli. CaM kinase II immunoreactivity was less intense in olfactory receptor axons of the antennal nerve and antennal lobe glial cells. Western blot analysis revealed a growing content of CaM kinase II in antennal lobe tissue throughout metamorphosis. Injection of the CaM kinase inhibitor KN-93 into pupae resulted in a reduced number of antennal lobe glial cells migrating into the neuropil to form borders around glomeruli. The results suggest that CaM kinase II is involved in glial cell migration.
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Affiliation(s)
- Christian Lohr
- Abteilung für Allgemeine Zoologie, Fachbereich Biologie, TU Kaiserslautern, Postfach 3049, 67653 Kaiserslautern, Germany.
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Gribovskaja I, Brownlow KC, Dennis SJ, Rosko AJ, Marletta MA, Stevens-Truss R. Calcium-binding sites of calmodulin and electron transfer by inducible nitric oxide synthase. Biochemistry 2005; 44:7593-601. [PMID: 15896003 DOI: 10.1021/bi0474517] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Like that of the neuronal nitric oxide synthase (nNOS), the binding of Ca(2+)-bound calmodulin (CaM) also regulates the activity of the inducible isoform (iNOS). However, the role of each of the four Ca(2+)-binding sites of CaM in the activity of iNOS is unclear. Using a series of single-point mutants of Drosophila melanogaster CaM, the effect that mutating each of the Ca(2+)-binding sites plays in the transfer of electrons within iNOS has been examined. The same Glu (E) to Gln (Q) mutant series of CaM used previously [Stevens-Truss, R., Beckingham, K., and Marletta, M. A. (1997) Biochemistry 36, 12337-12345] to study the role of the Ca(2+)-binding sites in the activity of nNOS was used for these studies. We demonstrate here that activity of iNOS is dependent on Ca(2+) being bound to sites II (B2Q) and III (B3Q) of CaM. Nitric oxide ((*)NO) producing activity (as measured using the hemoglobin assay) of iNOS bound to the B2Q and B3Q CaMs was found to be 41 and 43% of the wild-type activity, respectively. The site I (B1Q) and site IV (B4Q) CaM mutants only minimally affected (*)NO production (95 and 90% of wild-type activity, respectively). These results suggest that NOS isoforms, although all possessing a prototypical CaM binding sequence and requiring CaM for activity, interact with CaM differently. Moreover, iNOS activation by CaM, like nNOS, is not dependent on Ca(2+) being bound to all four Ca(2+)-binding sites, but has specific and distinct requirements. This novel information, in addition to helping us understand NOS, should aid in our understanding of CaM target activation.
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Affiliation(s)
- Irena Gribovskaja
- Department of Chemistry, Kalamazoo College, Kalamazoo, Michigan 49006, USA
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8
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Tombes RM, Faison MO, Turbeville JM. Organization and evolution of multifunctional Ca2+/CaM-dependent protein kinase genes. Gene 2003; 322:17-31. [PMID: 14644494 DOI: 10.1016/j.gene.2003.08.023] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The "multi-functional" Ca(2+) and calmodulin-dependent protein kinase, type II (CaMK-II) is an evolutionarily conserved protein. It has been found as a single gene in the horseshoe crab, marine sponge, sea urchin, nematode, and fruit fly, whereas most vertebrates possess four genes (alpha, beta, gamma, and delta). Species from fruit flies to humans encode alternative splice variants which are differentially targeted to phosphorylate diverse downstream targets of Ca(2+) signaling. By comparing known CaMK-II protein and nucleotide sequences, we have now provided evidence for the evolutionary relatedness of CaMK-IIs. Parsimony analyses unambiguously indicate that the four vertebrate CaMK-II genes arose via repeated duplications. Nucleotide phylogenies show consistent but moderate support for the placement of the vertebrate delta CaMK-II as the earliest diverging vertebrate gene. delta CaMK-II is the only gene with both central and C-terminal variable domains and has three to four times more intronic sequence than the other three genes. beta and gamma CaMK-II genes show strong sequence similarity and have comparable exon and intron organization and utilization. alpha CaMK-II is absent from amphibians (Xenopus laevis) and has the most restricted tissue specificity in mammals, whereas beta, gamma, and delta CaMK-IIs are expressed in most tissues. All 38 known mammalian CaMK-II splice variants were compiled with their tissue specificity and exon usage. Some of these variants use alternative 5' and 3' donors within a single exon as well as alternative promoters. These findings serve as an important benchmark for future phylogenetic, developmental, or biochemical studies on this important, conserved, and highly regulated gene family.
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Affiliation(s)
- Robert M Tombes
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284-2012, USA.
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9
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Takamatsu Y, Kishimoto Y, Ohsako S. Immunohistochemical study of Ca2+/calmodulin-dependent protein kinase II in the Drosophila brain using a specific monoclonal antibody. Brain Res 2003; 974:99-116. [PMID: 12742628 DOI: 10.1016/s0006-8993(03)02562-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
To analyze the distribution of Drosophila calcium/calmodulin-dependent protein kinase II (dCaMKII) in the adult brain, we generated monoclonal antibodies against the bacterially expressed 490-amino acid (a.a.) form of dCaMKII. One of those, named #18 antibody, was used for this study. Western blot analysis of the adult head extracts showed that the antibody specifically detects multiple bands between 55 and 60 kDa corresponding to the molecular weights of the splicing isoforms of dCaMKII. Epitope mapping revealed that it was in the region between 199 and 283 a.a. of dCaMKII. Preferential dCaMKII immunoreactivity in the embryonic nervous system, adult thoracic ganglion and gut, and larval neuro-muscular junction (NMJ) was consistent with previous observations by in situ hybridization and immunostaining with a polyclonal antibody at the NMJ, indicating that the antibody is applicable to immunohistochemistry. Although dCaMKII immunoreactive signal was low in the retina, it was found at regular intervals in the outer margin of the compound eye. These signals were most likely to be interommatidial bristle mechanosensory neurons. dCaMKII immunoreactivity in the brain was observed in almost all regions and relatively higher staining was found in the neuropilar region than in the cortex. Higher dCaMKII immunoreactivity in the mushroom body (MB) was found in the entire gamma lobe including the heel, and dorsal tips of the alpha and alpha' lobes, while cores of alpha and beta lobes were stained light. Finding abundant dCaMKII accumulation in the gamma lobe suggested that this lobe might especially require high levels of dCaMKII expression to function properly among MB lobes.
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Affiliation(s)
- Yoshiki Takamatsu
- Department of Brain Structure, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Japan.
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Hudmon A, Schulman H. Neuronal CA2+/calmodulin-dependent protein kinase II: the role of structure and autoregulation in cellular function. Annu Rev Biochem 2002; 71:473-510. [PMID: 12045104 DOI: 10.1146/annurev.biochem.71.110601.135410] [Citation(s) in RCA: 506] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Highly enriched in brain tissue and present throughout the body, Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is central to the coordination and execution of Ca(2+) signal transduction. The substrates phosphorylated by CaMKII are implicated in homeostatic regulation of the cell, as well as in activity-dependent changes in neuronal function that appear to underlie complex cognitive and behavioral responses, including learning and memory. The architecture of CaMKII holoenzymes is unique in nature. The kinase functional domains (12 per holoenzyme) are attached by stalklike appendages to a gear-shaped core, grouped into two clusters of six. Each subunit contains a catalytic, an autoregulatory, and an association domain. Ca(2+)/calmodulin (CaM) binding disinhibits the autoregulatory domain, allowing autophosphorylation and complex changes in the enzyme's sensitivity to Ca(2+)/CaM, including the generation of Ca(2+)/CaM-independent activity, CaM trapping, and CaM capping. These processes confer a type of molecular memory to the autoregulation and activity of CaMKII. Its function is intimately shaped by its multimeric structure, autoregulation, isozymic type, and subcellular localization; these features and processes are discussed as they relate to known and potential cellular functions of this multifunctional protein kinase.
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Affiliation(s)
- Andy Hudmon
- Department of Neurobiology, Stanford University School of Medicine, 299 Campus Drive, Stanford, California 94305, USA.
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11
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Bayer K, De Koninck P, Schulman H. Alternative splicing modulates the frequency-dependent response of CaMKII to Ca(2+) oscillations. EMBO J 2002; 21:3590-7. [PMID: 12110572 PMCID: PMC126106 DOI: 10.1093/emboj/cdf360] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Ca(2+) oscillations are required in various signal trans duction pathways, and contain information both in their amplitude and frequency. Remarkably, the Ca(2+)/calmodulin(CaM)-dependent protein kinase II (CaMKII) can decode such frequencies. A Ca(2+)/CaM-stimulated autophosphorylation leads to Ca(2+)/CaM-independent (autonomous) activity of the kinase that outlasts the initial stimulation. This autonomous activity increases exponentially with the frequency of Ca(2+) oscillations. Here we show that three beta-CaMKII splice variants (beta(M), beta and beta(e)') have very similar specific activity and maximal autonomy. However, their autonomy generated by Ca(2+) oscillations differs significantly. A mechanistic basis was found in alterations of the CaM activation constant and of the initial rate of autophosphorylation. Structurally, the splice variants differ only in a variable 'linker' region between the kinase and association domains. Therefore, we propose that differences in relative positioning of kinase domains within multimeric holoenzymes are responsible for the observed effects. Notably, the beta-CaMKII splice variants are differentially expressed, even among individual hippocampal neurons. Taken together, our results suggest that alternative splicing provides cells with a mechanism to modulate their sensitivity to Ca(2+) oscillations.
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Affiliation(s)
- K.Ulrich Bayer
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305-5125, USA and
Centre de Recherche Université Laval Robert-Giffard, Beauport, Québec G1J 2G3, Canada Corresponding authors e-mail: or
| | - Paul De Koninck
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305-5125, USA and
Centre de Recherche Université Laval Robert-Giffard, Beauport, Québec G1J 2G3, Canada Corresponding authors e-mail: or
| | - Howard Schulman
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305-5125, USA and
Centre de Recherche Université Laval Robert-Giffard, Beauport, Québec G1J 2G3, Canada Corresponding authors e-mail: or
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12
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Wang Z, Wilson GF, Griffith LC. Calcium/calmodulin-dependent protein kinase II phosphorylates and regulates the Drosophila eag potassium channel. J Biol Chem 2002; 277:24022-9. [PMID: 11980904 DOI: 10.1074/jbc.m201949200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Modulation of neuronal excitability is believed to be an important mechanism of plasticity in the nervous system. Calcium/calmodulin-dependent protein kinase II (CaMKII) has been postulated to regulate the ether à go-go (eag) potassium channel in Drosophila. Inhibition of CaMKII and mutation of the eag gene both cause hyperexcitability at the larval neuromuscular junction (NMJ) and memory formation defects in the adult. In this study, we identify a single site, threonine 787, as the major CaMKII phosphorylation site in Eag. This site can be phosphorylated by CaMKII both in a heterologous cell system and in vivo at the larval NMJ. Expression of Eag in Xenopus oocytes was used to assess the function of phosphorylation. Injection of either a specific CaMKII inhibitor peptide or lavendustin C, another CaMKII inhibitor, reduced Eag current amplitude acutely. Mutation of threonine 787 to alanine also reduced amplitude. Moreover, both CaMKII inhibition and the alanine mutation accelerated inactivation. The reduction in current amplitudes and the accelerated inactivation of dephosphorylated Eag channels would result in decreased outward potassium currents and hyperexcitability at presynaptic terminals and, thus, are consistent with the NMJ phenotype observed when CaMKII is inhibited. These results show that Eag is a substrate of CaMKII and suggest that direct modulation of potassium channels may be an important function of this kinase.
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Affiliation(s)
- Zheng Wang
- Department of Biology and Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts 02454-9110, USA
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Hsu LS, Chen GD, Lee LS, Chi CW, Cheng JF, Chen JY. Human Ca2+/calmodulin-dependent protein kinase kinase beta gene encodes multiple isoforms that display distinct kinase activity. J Biol Chem 2001; 276:31113-23. [PMID: 11395482 DOI: 10.1074/jbc.m011720200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ca(+2)/calmodulin-dependent protein kinases (CaMKs) are activated upon binding of Ca(+2)/calmodulin. To gain maximal activity, CaMK I and CaMK IV can be further phosphorylated by an upstream kinase, CaMK kinase (CaMKK). We previously isolated cDNA clones encoding human CaMKK beta isoforms that are heterogeneous in their 3'-sequences (Hsu, L.-S., Tsou, A.-P., Chi, C.-W., Lee, C.-H., and Chen, J.-Y. (1998) J. Biomed. Sci. 5, 141-149). In the present study, we examined the genomic organization and transcription of the human CaMKK beta gene. The human CaMKK beta locus spans more than 40 kilobase pairs and maps to chromosome 12q24.2. It is organized into 18 exons and 17 introns that are flanked by typical splice donor and acceptor sequences. Two major species of transcripts, namely the beta1 (5.6 kilobase pairs) and beta2 (2.9 kilobase pairs), are generated through differential usage of polyadenylation sites located in the last and penultimate exons. Additional forms of CaMKK beta transcripts were also identified that resulted from alternative splicing of the internal exons 14 and/or 16. These isoforms display differential expression patterns in human tissues and tumor-derived cell lines. They also exhibit a distinct ability to undergo autophosphorylation and to phosphorylate the downstream kinases CaMK I and CaMK IV. The differential expression of CaMKK beta isoforms with distinct activity further suggests the complexity of the regulation of the CaMKK/CaMK cascade and an important role for CaMKK in the action of Ca(+2)-mediated cellular responses.
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Affiliation(s)
- L S Hsu
- Graduate Institute of Life Sciences, National Defense Medical Center, Institute of Biomedical Sciences, Academia Sinica, Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China
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14
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Abstract
Ca2+-independent forms of nitric-oxide synthase have significant activity when the endogenous calmodulin subunit is Ca2+ free. Further activation is seen when Ca2+ is added. We have examined the activation of a Ca2+-independent nitric-oxide synthase variant and its two point mutants that are more dependent on Ca2+ for activation using mutant calmodulins containing non-functional Ca2+-binding sites. These studies provide evidence that the Ca2+-independent activity of these enzymes can be exerted through specific adapted interactions between the enzyme and the Ca2+-binding site 2 of calmodulin. Further, the results suggest that EGTA-sensitive metals other than Ca2+ complexed to calmodulin may be involved in maximal activation of these nitric-oxide synthase variants.
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Affiliation(s)
- S J Lee
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9040, USA.
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GuptaRoy B, Marwaha N, Pla M, Wang Z, Nelson HB, Beckingham K, Griffith LC. Alternative splicing of Drosophila calcium/calmodulin-dependent protein kinase II regulates substrate specificity and activation. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2000; 80:26-34. [PMID: 11039726 DOI: 10.1016/s0169-328x(00)00115-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Drosophila calcium/calmodulin-dependent protein kinase II is alternatively spliced to generate multiple isoforms that vary only in a region between the calmodulin-binding domain and the association domain. This variation has been shown to modulate activation of the enzyme by calmodulin. In this study we examine the ability of seven of the Drosophila isoforms to phosphorylate purified protein substrates and to be inhibited by a substrate analog, and the response of six of the isoforms to a mutant form of calmodulin (V91G) that was isolated in a genetic screen. Significant variation in Kms for Eag, a potassium channel, and Adf-1, a transcription factor, were found. In the case of the a peptide inhibitor, AC3I, there were significant variations in Ki between isoforms. Kact for V91G calmodulin was increased for all of the isoforms. In addition, one isoform, RI, exhibited a lower Vmax when assayed with this mutant CaM. These results indicate that the variable domain of calcium/calmodulin-dependent protein kinase II is capable of altering the substrate specificity of the catalytic domain and the activation response to calmodulin.
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Affiliation(s)
- B GuptaRoy
- Department of Biology and Volen Center for Complex Systems, Brandeis University, Waltham, MA 02254, USA
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16
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Wang P, Wu YL, Zhou TH, Sun Y, Pei G. Identification of alternative splicing variants of the beta subunit of human Ca(2+)/calmodulin-dependent protein kinase II with different activities. FEBS Lett 2000; 475:107-10. [PMID: 10858498 DOI: 10.1016/s0014-5793(00)01634-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The beta subunit of human Ca(2+)/calmodulin-dependent protein kinase II (beta CaMKII) was identified by searching through an expressed sequence tag database and rapid amplification of cDNA 5'-ends and was assigned to chromosome 7. Reverse transcription-polymerase chain reaction and sequencing analysis identified at least five alternative splicing variants of beta CaMKII (beta, beta6, betae, beta'e, and beta7) in brain and two of them (beta6 and beta7) were first detected in any species. When expressed in HEK 293 cells, the Ca(2+)/calmodulin-dependent kinase activity of beta7, the shortest variant, was much lower than that of either beta (the longest one) or betae (the medium one), suggesting possible regulation of beta CaMKII activity by alternative splicing.
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Affiliation(s)
- P Wang
- Shanghai Institute of Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, PR China
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17
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Kwiatkowski AP, McGill JM. Alternative splice variant of gamma-calmodulin-dependent protein kinase II alters activation by calmodulin. Arch Biochem Biophys 2000; 378:377-83. [PMID: 10860555 DOI: 10.1006/abbi.2000.1846] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calmodulin-dependent protein kinase II (CaMKII) is a ubiquitous, multifunctional enzyme family involved in the regulation of a variety of Ca(2+)-signaling pathways. These family members are expressed from four highly homologous genes (alpha, beta, gamma, and delta) with similar catalytic properties. Additional isoforms of each gene, created by alternative splicing of variable regions I-XI, are differentially expressed in various cell types. gammaB, gammaC, gammaD, gammaE, gammaF, gammaGs, and gammaH CaMKII isoforms are expressed in the biliary epithelium; however, little is known about their roles in these cells. We began our studies into the function of these variable regions by examining the effects of variable region I on kinase activation and calmodulin binding. Activities and calmodulin binding properties of gammaB and gammaGs, which differ only by the exclusion or inclusion of this region, were compared. The K(0.5) for calmodulin was 2.5-fold lower for gammaGs than gammaB. In contrast, gammaB bound calmodulin more tightly in a calmodulin overlay assay. Mutation of variable regions I's charged residue, gammaGs-R318E, resulted in an enzyme with intermediate activation properties but a calmodulin affinity similar to gammaB. Thus, variable region I appears to modulate calmodulin sensitivity, in part, through charge-charge interactions. This altered threshold of activation may modulate cellular responses to gradients of Ca(2+)/calmodulin in the biliary tract.
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Affiliation(s)
- A P Kwiatkowski
- Division of Gastroenterology and Hepatology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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18
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Brocke L, Chiang LW, Wagner PD, Schulman H. Functional implications of the subunit composition of neuronal CaM kinase II. J Biol Chem 1999; 274:22713-22. [PMID: 10428854 DOI: 10.1074/jbc.274.32.22713] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The assembly of 6-12 subunits of Ca(2+)/calmodulin-dependent kinase II (CaM kinase II) into holoenzymes is an important structural feature of the enzyme and its postulated role as a molecular detector of Ca(2+) oscillations. Using single cell reverse transcriptase-polymerase chain reaction, we show that alpha- and beta-CaM kinase II mRNAs are simultaneously present in the majority of hippocampal neurons examined and that co-assembly of their protein products into heteromers is therefore possible. The subunit composition of CaM kinase II holoenzymes was analyzed by immunoprecipitation with subunit-specific monoclonal antibodies. Rat forebrain CaM kinase II consists of heteromers composed of alpha and beta subunits at a ratio of 2:1 and homomers composed of only alpha subunits. We examined the functional effect of the heteromeric assembly by analyzing the calmodulin dependence of autophosphorylation. Recombinant homomers of alpha- or beta-CaM kinase II, as well as of alternatively spliced beta isoforms, have distinct calmodulin dependences for autophosphorylation based on differences in their calmodulin affinities. Half-maximal autophosphorylation of alpha is achieved at 130 nM calmodulin, while that for beta occurs at 15 nM calmodulin. In CaM kinase II isolated from rat forebrain, however, the calmodulin dependence for autophosphorylation of the beta subunits is shifted toward that of alpha homomers. This suggests that Thr(287) in beta subunits is phosphorylated by alpha subunits present in the same holoenzyme. Once autophosphorylated, beta-CaM kinase II traps calmodulin by reducing the rate of calmodulin dissociation.
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Affiliation(s)
- L Brocke
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305-5125, USA
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19
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Zhou Y, Schopperle WM, Murrey H, Jaramillo A, Dagan D, Griffith LC, Levitan IB. A dynamically regulated 14-3-3, Slob, and Slowpoke potassium channel complex in Drosophila presynaptic nerve terminals. Neuron 1999; 22:809-18. [PMID: 10230800 DOI: 10.1016/s0896-6273(00)80739-4] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Slob is a novel protein that binds to the carboxy-terminal domain of the Drosophila Slowpoke (dSlo) calcium-dependent potassium (K(Ca)) channel. A yeast two-hybrid screen with Slob as bait identifies the zeta isoform of 14-3-3 as a Slob-binding protein. Coimmunoprecipitation experiments from Drosophila heads and transfected cells confirm that 14-3-3 interacts with dSlo via Slob. All three proteins are colocalized presynaptically at Drosophila neuromuscular junctions. Two serine residues in Slob are required for 14-3-3 binding, and the binding is dynamically regulated in Drosophila by calcium/calmodulin-dependent kinase II (CaMKII) phosphorylation. 14-3-3 coexpression dramatically alters dSlo channel properties when wild-type Slob is present but not when a double serine mutant Slob that is incapable of binding 14-3-3 is present. The results provide evidence for a dSlo/Slob/14-3-3 regulatory protein complex.
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Affiliation(s)
- Y Zhou
- Department of Biochemistry, Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts 02454, USA
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20
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Yamaguchi K, Yamaguchi F, Miyamoto O, Sugimoto K, Konishi R, Hatase O, Tokuda M. Calbrain, a novel two EF-hand calcium-binding protein that suppresses Ca2+/calmodulin-dependent protein kinase II activity in the brain. J Biol Chem 1999; 274:3610-6. [PMID: 9920909 DOI: 10.1074/jbc.274.6.3610] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A cDNA clone that encodes a novel Ca2+-binding protein was isolated from a human brain cDNA library. The gene for this clone, termed calbrain, encodes a 70-amino acid polypeptide with a predicted molecular mass of 8.06 kDa. The analysis of deduced amino acid sequence revealed that calbrain contains two putative EF-hand motifs that show significantly high homology to those of the calmodulin (CaM) family rather than two EF-hand protein families. By Northern hybridization analysis, an approximate 1.5-kilobase pair transcript of calbrain was detected exclusively in the brain, and in situ hybridization study revealed its abundant expression in the hippocampus, habenular area in the epithalamus, and in the cerebellum. A recombinant calbrain protein showed a Ca2+ binding capacity, suggesting the functional potency as a regulator of Ca2+-mediated cellular processes. Ca2+/calmodulin-dependent kinase II, the most abundant protein kinase in the hippocampus and strongly implicated in the basic neuronal functions, was used to evaluate the physiological roles of calbrain. Studies in vitro revealed that calbrain competitively inhibited CaM binding to Ca2+/calmodulin-dependent kinase II (Ki = 129 nM) and reduced its kinase activity and autophosphorylation.
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Affiliation(s)
- K Yamaguchi
- Departments of Physiology, Faculty of Medicine, Kagawa Medical University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan
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21
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Arredondo L, Nelson HB, Beckingham K, Stern M. Increased transmitter release and aberrant synapse morphology in a Drosophila calmodulin mutant. Genetics 1998; 150:265-74. [PMID: 9725845 PMCID: PMC1460322 DOI: 10.1093/genetics/150.1.265] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The ubiquitous calcium-binding protein calmodulin (CaM) has been implicated in the development and function of the nervous system in a variety of eukaryotic organisms. We have generated mutations in the single Drosophila Calmodulin (Cam) gene and examined the effects of these mutations on behavior, synaptic transmission at the larval neuromuscular junction, and structure of the larval motor nerve terminal. Flies hemizygous for Cam3c1, a mutation in the first Ca2+-binding site, exhibit behavioral, neurophysiological, and neuroanatomical abnormalities. In particular, adults exhibit defects in locomotion, coordination, and flight. Larvae exhibit increased neurotransmitter release from the motor nerve terminal at low [Ca2+] in the presence of the K+ channel-blocking drug quinidine. In addition, synaptic bouton structure at motor nerve terminals is altered. These effects are distinct from those produced by altering the activity of the CaM target enzymes CaM-activated kinase II (CaMKII) and CaM-activated adenylyl cyclase (CaMAC). Furthermore, previous in vitro studies of mutant Cam3c1 demonstrated that although its Ca2+ affinity is decreased, Cam3c1 protein can activate CaMKII, CaMAC, and CaM-activated phosphatase calcineurin in a manner similar to wild-type CaM. Thus, the Cam3c1 mutation might affect Ca2+ buffering or interfere with the activation or inhibition of a CaM target distinct from CaMKII or CaMAC.
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Affiliation(s)
- L Arredondo
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005-1892, USA
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22
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Griffith LC. Drosophila melanogaster as a model system for the study of the function of calcium/calmodulin-dependent protein kinase II in synaptic plasticity. INVERTEBRATE NEUROSCIENCE : IN 1997; 3:93-102. [PMID: 9783436 DOI: 10.1007/bf02480364] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Drosophila melanogaster has been used as a biological model system for almost a century. In the last several decades, Drosophila has been used as a system to probe the molecular basis of behavior and discoveries in the fly have been at the forefront of the elucidation of important basic mechanisms. This review will outline the variety of approaches that make Drosophila an excellent model system with which to study the function of the enzyme calcium/calmodulin-dependent protein kinase II (CaMKII) in synaptic plasticity. CaMKII has a well documented role in behavior and synaptic plasticity in both vertebrates and invertebrates. The behavioral and genetic richness of Drosophila allow for a multi-level approach to understanding the physiological roles of this enzyme's function.
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Affiliation(s)
- L C Griffith
- Department of Biology, Brandeis University MS008, Waltham, MA 02254-9110, USA
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