Kinase II (kinase + ii)

Distribution by Scientific Domains

Kinds of Kinase II

  • ca2+/calmodulin-dependent protein kinase ii
  • calcium protein kinase ii
  • calmodulin-dependent protein kinase ii
  • protein kinase ii

  • Selected Abstracts

    Modulation of the Phosphorylation and Activity of Calcium/Calmodulin-Dependent Protein Kinase II by Zinc

    Imre Lengyel
    Calcium/calmodulin-dependent protein kinase II (CaMPK-II) is a key regulatory enzyme in living cells. Modulation of its activity, therefore, could have a major impact on many cellular processes. We found that Zn2+ has multiple functional effects on CaMPK-II. Zn2+ generated a Ca2+/CaM-independent activity that correlated with the autophosphorylation of Thr286, inhibited Ca2+/CaM binding that correlated with the autophosphorylation of Thr306, and inhibited CaMPK-II activity at high concentrations that correlated with the autophosphorylation of Ser279. The relative level of autophosphorylation of these three sites was dependent on the concentration of zinc used. The autophosphorylation of at least these three sites, together with Zn2+ binding, generated an increased mobility form of CaMPK-II on sodium dodecyl sulfate gels. Overall, autophosphorylation induced by Zn2+ converts CaMPK-II into a different form than the binding of Ca2+/CaM. In certain nerve terminals, where Zn2+ has been shown to play a neuromodulatory role and is present in high concentrations, Zn2+ may turn CaMPK-II into a form that would be unable to respond to calcium signals. [source]

    Wnt Pathway Regulation in Chronic Renal Allograft Damage

    C. Von Toerne
    The Wnt signaling pathway, linked to development, has been proposed to be recapitulated during the progressive damage associated with chronic organ failure. Chronic allograft damage following kidney transplantation is characterized by progressive fibrosis and a smoldering inflammatory infiltrate. A modified, Fischer 344 (RT1lvl) to Lewis (RT1l) rat renal allograft model that reiterates many of the major pathophysiologic processes seen in patients with chronic allograft failure was used to study the progressive disease phenotype and specific gene product expression by immunohistochemistry and transcriptomic profiling. Central components of the Tgfb, canonical Wnt and Wnt-Ca2+ signaling pathways were significantly altered with the development of chronic damage. In the canonical Wnt pathway, Wnt3, Lef1 and Tcf1 showed differential regulation. Target genes Fn1, Cd44, Mmp7 and Nos2 were upregulated and associated with the progression of renal damage. Changes in the Wnt-Ca2+ pathway were evidenced by increased expression of Wnt6, Wnt7a, protein kinase C, Cam Kinase II and Nfat transcription factors and the target gene vimentin. No evidence for alterations in the Wnt planar cell polarity (PCP) pathway was detected. Overall results suggest cross talk between the Wnt and Tgfb signaling pathways during allograft inflammatory damage and present potential targets for therapeutic intervention. [source]

    Calmodulin kinase II initiates arrhythmogenicity during metabolic acidification in murine hearts

    ACTA PHYSIOLOGICA, Issue 1 2009
    T. H. Pedersen
    Abstract Aim:, The multifunctional signal molecule calmodulin kinase II (CaMKII) has been associated with cardiac arrhythmogenesis under conditions where its activity is chronically elevated. Recent studies report that its activity is also acutely elevated during acidosis. We test a hypothesis implicating CaMKII in the arrhythmogenesis accompanying metabolic acidification. Methods:, We obtained monophasic action potential recordings from Langendorff-perfused whole heart preparations and single cell action potentials (AP) using whole-cell patch-clamped ventricular myocytes. Spontaneous sarcoplasmic reticular (SR) Ca2+release events during metabolic acidification were investigated using confocal microscope imaging of Fluo-4-loaded ventricular myocytes. Results:, In Langendorff-perfused murine hearts, introduction of lactic acid into the Krebs-Henseleit perfusate resulted in abnormal electrical activity and ventricular tachycardia. The CaMKII inhibitor, KN-93 (2 ,m), reversibly suppressed this spontaneous arrhythmogenesis during intrinsic rhythm and regular 8 Hz pacing. However, it failed to suppress arrhythmia evoked by programmed electrical stimulation. These findings paralleled a CaMKII-independent reduction in the transmural repolarization gradients during acidosis, which previously has been associated with the re-entrant substrate under other conditions. Similar acidification produced spontaneous AP firing and membrane potential oscillations in patch-clamped isolated ventricular myocytes when pipette solutions permitted cytosolic Ca2+ to increase following acidification. However, these were abolished by both KN-93 and use of pipette solutions that held cytosolic Ca2+ constant during acidosis. Acidosis also induced spontaneous Ca2+ waves in isolated intact Fluo-4-loaded myocytes studied using confocal microscopy that were abolished by KN-93. Conclusion:, These findings together implicate CaMKII-dependent SR Ca2+ waves in spontaneous arrhythmic events during metabolic acidification. [source]

    Regulation of neuronal excitability in Drosophila by constitutively active CaMKII

    Demian Park
    Abstract The ability of calcium/calmodulin-dependent protein kinase II (CaMKII) to become calcium independent after autophosphorylation makes this enzyme a temporal marker of neuronal activity. Here we show that the calcium-independent form of CaMKII has unique effects on larval viability, locomotion, and neuronal excitability in Drosophila. Expression of constitutively active T287D, but not calcium-dependent T287A, mutant CaMKII in Drosophila neurons resulted in decreased viability, behavioral defects, and failure of action potential propagation. The actions of T287D may be mediated, at least in part, by increased potassium conductances. Expression of T287D CaMKII also stimulated an increase in the number of boutons at the larval neuromuscular junction, but did not affect the mechanics of release. This study defines a role for autophosphorylation of CaMKII in the regulation of multiple neuronal functions including the intrinsic properties of neurons. 2002 Wiley Periodicals, Inc. J Neurobiol 52: 24,42, 2002 [source]

    Impairment of CaMKII activation and attenuation of neuropathic pain in mice lacking NR2B phosphorylated at Tyr1472

    Shinji Matsumura
    Abstract Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a key mediator of long-term potentiation (LTP), which can be triggered by N -methyl- d -aspartate (NMDA) receptor-mediated Ca2+ influx. We previously demonstrated that Fyn kinase-mediated phosphorylation of NR2B subunits of NMDA receptors at Tyr1472 in the dorsal horn was involved in a neuropathic pain state even 1 week after nerve injury. Here we show that Y1472F-KI mice with a knock-in mutation of the Tyr1472 site to phenylalanine did not exhibit neuropathic pain induced by L5 spinal nerve transection, whereas they did retain normal nociceptive responses and induction of inflammatory pain. Phosphorylation of NR2B at Tyr1472 was only impaired in the spinal cord of Y1472F-KI mice among the major phosphorylation sites. There was no difference in the Ca2+ response to glutamate and sensitivity to NMDA receptor antagonists between naive wild-type and Y1472F-KI mice, and the Ca2+ response to glutamate was attenuated in the Y1472F-KI mice after nerve injury. Autophosphorylation of CaMKII at Thr286 was markedly impaired in Y1472F-KI mice after nerve injury, but there was no difference in phosphorylation of CaMKII at Thr305 or protein kinase C, at Thr674, and activation of neuronal nitric oxide synthase and microglia in the superficial layer of spinal cord between wild-type and Y1472F-KI mice after the operation. These results demonstrate that the attenuation of neuropathic pain is caused by the impaired NMDA receptor-mediated CaMKII signaling in Y1472F-KI mice, and suggest that autophosphorylation of CaMKII at Thr286 plays a central part not only in LTP, but also in persistent neuropathic pain. [source]

    Transient viral-mediated overexpression of ,-calcium/calmodulin-dependent protein kinase II in the nucleus accumbens shell leads to long-lasting functional upregulation of ,-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors: dopamine type-1 receptor and protein kinase A dependence

    B. F. Singer
    Abstract Calcium/calmodulin-dependent protein kinase II (CaMKII) activity is necessary for the long-lasting expression of locomotor sensitization and enhanced drug-taking observed in rats previously exposed to psychostimulants. Exposure to these drugs also transiently increases ,CaMKII levels in the nucleus accumbens (NAcc), an effect that, when mimicked by transient viral-mediated overexpression of ,CaMKII in NAcc shell neurons, leads to long-lasting enhancement in locomotor responding to amphetamine and NAcc ,-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA). The present experiments characterized the dopamine (DA) dependence of the functional AMPA receptor upregulation observed long after transient overexpression of ,CaMKII. Rats infected with herpes simplex virus-,CaMKII in the NAcc shell showed a transient increase in ,CaMKII levels that peaked at 4 days post-infection and returned to baseline 8 days later. When challenged with AMPA (0.8 nmol/side) in the NAcc shell at 20 days post-infection, these rats showed enhanced locomotion compared with controls. This sensitized locomotor response was blocked when AMPA was coinfused with either the DA type-1 receptor antagonist SCH23390 (0.8 nmol/side) or the protein kinase A inhibitor Rp-cAMPS (80 nmol/side). Neither SCH23390 nor Rp-cAMPS produced locomotor effects when infused by itself into the NAcc shell. Furthermore, these antagonists did not block the acute non-sensitized locomotor response to AMPA observed in control rats. These findings show that transient viral-mediated overexpression of ,CaMKII in neurons of the NAcc shell leads to long-lasting functional upregulation of AMPA receptors that is DA type-1 receptor and protein kinase A dependent. Thus, transient increases in levels of ,CaMKII in the NAcc shell produce long-lasting changes in the way that DA and glutamate interact in this site to generate locomotor behavior. [source]

    Calcium,calmodulin-dependent protein kinase II phosphorylation modulates PSD-95 binding to NMDA receptors

    Fabrizio Gardoni
    Abstract At the postsynaptic membrane of excitatory synapses, NMDA-type receptors are bound to scaffolding and signalling proteins that regulate the strength of synaptic transmission. The cytosolic tails of the NR2A and NR2B subunits of NMDA receptor bind to calcium,calmodulin-dependent protein kinase II (CaMKII) and to members of the MAGUK family such as PSD-95. In particular, although NR2A and NR2B subunits are highly homologous, the sites of their interaction with CaMKII as well as the regulation of this binding differ. We identified PSD-95 phosphorylation as a molecular mechanism responsible for the dynamic regulation of the interaction of both PSD-95 and CaMKII with the NR2A subunit. CaMKII-dependent phosphorylation of PSD-95 occurs both in vitro, in GST-PSD-95 fusion proteins phosphorylated by purified active CaMKII, and in vivo, in transfected COS-7 as well as in cultured hippocampal neurons. We identified Ser73 as major phosphorylation site within the PDZ1 domain of PSD-95, as confirmed by point mutagenesis experiments and by using a phospho-specific antibody. PSD-95 Ser73 phosphorylation causes NR2A dissociation from PSD-95, while it does not interfere with NR2B binding to PSD-95. These results identify CaMKII-dependent phosphorylation of the PDZ1 domain of PSD-95 as a mechanism regulating the signalling transduction pathway downstream NMDA receptor. [source]

    Interaction of LDL receptor-related protein 4 (LRP4) with postsynaptic scaffold proteins via its C-terminal PDZ domain-binding motif, and its regulation by Ca2+/calmodulin-dependent protein kinase II

    Qing-Bao Tian
    No abstract is available for this article. [source]

    Somatodendritic autoreceptor regulation of serotonergic neurons: dependence on l -tryptophan and tryptophan hydroxylase-activating kinases

    Rong-Jian Liu
    Abstract The somatodendritic 5-HT1A autoreceptor has been considered a major determinant of the output of the serotonin (5-HT) neuronal system. However, recent studies in brain slices from the dorsal raphe nucleus have questioned the relevance of 5-HT autoinhibition under physiological conditions. In the present study, we found that the difficulty in demonstrating 5-HT tonic autoinhibition in slice results from in vitro conditions that are unfavorable for sustaining 5-HT synthesis. Robust, tonic 5-HT1A autoinhibition can be restored by reinstating in vivo 5-HT synthesizing conditions with the initial 5-HT precursor l -tryptophan and the tryptophan hydroxylase co-factor tetrahydrobiopterin (BH4). The presence of tonic autoinhibition under these conditions was revealed by the disinhibitory effect of a low concentration of the 5-HT1A antagonist WAY 100635. Neurons showing an autoinhibitory response to l -tryptophan were confirmed immunohistochemically to be serotonergic. Once conditions for tonic autoinhibition had been established in raphe slice, we were able to show that 5-HT autoinhibition is critically regulated by the tryptophan hydroxylase-activating kinases calcium/calmodulin protein kinase II (CaMKII) and protein kinase A (PKA). In addition, at physiological concentrations of l -tryptophan, there was an augmentation of 5-HT1A receptor-mediated autoinhibition when the firing of 5-HT cells activated with increasing concentrations of the ,1 adrenoceptor agonist phenylephrine. Increased calcium influx at higher firing rates, by activating tryptophan hydroxylase via CaMKII and PKA, can work together with tryptophan to enhance negative feedback control of the output of the serotonergic system. [source]

    A role for synGAP in regulating neuronal apoptosis

    Irene Knuesel
    Abstract The brain-specific Ras/Rap GTPase-activating protein synGAP is a major component of the postsynaptic density at glutamatergic synapses. It is a target for phosphorylation by Ca2+/calmodulin-dependent protein kinase II, which up-regulates its GTPase-activating activity. Thus, SynGAP may play an important role in coupling N -methyl- d -aspartate-type glutamate receptor activation to signaling pathways downstream of Ras or Rap. Homozygous deletion of synGAP is lethal within the first few days after birth. Therefore, to study the functions of synGAP, we used the cre/loxP recombination system to produce conditional mice mutants in which gradual loss of synGAP begins at ,,1 week, and usually becomes maximal by 3 weeks, after birth. The resulting phenotypes fall into two groups. In a small group, the level of synGAP protein is reduced to 20,25% of wild type, and they die at 2,3 weeks of age. In a larger group, the levels remain higher than ,,40% of wild type, and they survive and remain healthy. In all mutants, however, an abnormally high number of neurons in the hippocampus and cortex undergo apoptosis, as detected by caspase-3 activation. The effect is cell autonomous, occurring only in neuronal types in which the synGAP gene is eliminated. The level of caspase-3 activation in neurons correlates inversely with the level of synGAP protein measured at 2 and 8 weeks after birth, indicating that neuronal apoptosis is enhanced by reduction of synGAP. These data show that synGAP plays a role in regulation of the onset of apoptotic neuronal death. [source]

    Bidirectional synaptic plasticity as a consequence of interdependent Ca2+ -controlled phosphorylation and dephosphorylation pathways

    Pablo D'Alcantara
    Abstract Postsynaptic Ca2+ signals of different amplitudes and durations are able to induce either long-lasting potentiation (LPT) or depression (LTD). The bidirectional character of synaptic plasticity may result at least in part from an increased or decreased responsiveness of the glutamatergic ,-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPA-R) due to the modification of conductance and/or channel number, and controlled by the balance between the activities of phosphorylation and dephosphorylation pathways. AMPA-R depression can be induced by a long-lived Ca2+ signal of moderate amplitude favouring the activation of the dephosphorylation pathway, whereas a shorter but higher Ca2+ signal would induce AMPA-R potentiation resulting from the preferential activation of the phosphorylation pathway. Within the framework of a model involving calcium/calmodulin-dependent protein kinase II (CaMKII), calcineurin (PP2B) and type 1 protein phosphatase (PP1), we aimed at delineating the conditions allowing a biphasic U-shaped relationship between AMPA-R and Ca2+ signal amplitude, and thus bidirectional plasticity. Our theoretical analysis shows that such a property may be observed if the phosphorylation pathway: (i) displays higher cooperativity in its Ca2+ -dependence than the dephosphorylation pathway; (ii) displays a basal Ca2+ -independent activity; or (iii) is directly inhibited by the dephosphorylation pathway. Because the experimentally observed inactivation of CaMKII by PP1 accounts for this latter characteristic, we aimed at verifying whether a realistic model using reported parameters values can simulate the induction of either LTP or LTD, depending on the time and amplitude characteristics of the Ca2+ signal. Our simulations demonstrate that the experimentally observed bidirectional nature of Ca2+ -dependent synaptic plasticity could be the consequence of the PP1-mediated inactivation of CaMKII. [source]

    Differential effects of acute and chronic exercise on plasticity-related genes in the rat hippocampus revealed by microarray

    Raffaella Molteni
    Abstract Studies were performed to determine the effects of acute and chronic voluntary periods of exercise on the expression of hippocampal genes. RNAs from rodents exposed to a running wheel for 3, 7 and 28 days were examined using a microarray with 1176 cDNAs expressed primarily in the brain. The expression of selected genes was quantified by Taqman RT-PCR or RNase protection assay. The largest up-regulation was observed in genes involved with synaptic trafficking (synapsin I, synaptotagmin and syntaxin); signal transduction pathways (Ca2+/calmodulin-dependent protein kinase II, CaM-KII; mitogen-activated/extracellular signal-regulated protein kinase, MAP-K/ERK I and II; protein kinase C, PKC-,) or transcription regulators (cyclic AMP response element binding protein, CREB). Genes associated with the glutamatergic system were up-regulated (N -methyl- d -aspartate receptor, NMDAR-2A and NMDAR-2B and excitatory amino acid carrier 1, EAAC1), while genes related to the gamma-aminobutyric acid (GABA) system were down-regulated (GABAA receptor, glutamate decarboxylase GAD65). Brain-derived neurotrophic factor (BDNF) was the only trophic factor whose gene was consistently up-regulated at all timepoints. These results, together with the fact that most of the genes up-regulated have a recognized interaction with BDNF, suggest a central role for BDNF on the effects of exercise on brain plasticity. The temporal profile of gene expression seems to delineate a mechanism by which specific molecular pathways are activated after exercise performance. For example, the CaM-K signal system seems to be active during acute and chronic periods of exercise, while the MAP-K/ERK system seems more important during long-term exercise. [source]

    N-methyl- d -aspartate enhancement of the glycine response in the rat sacral dorsal commissural neurons

    Abstract The effect of N-methyl- d -aspartate (NMDA) on the glycine (Gly) response was examined in neurons acutely dissociated from the rat sacral dorsal commissural nucleus (SDCN) using the nystatin-perforated patch-recording configuration under voltage-clamp conditions. The application of 100 ,m NMDA to SDCN neurons reversibly potentiated Gly-activated Cl, currents (IGly) without affecting the Gly binding affinity and the reversal potential of IGly. A selective NMDA receptor antagonist, APV (100 ,m), blocked the NMDA-induced potentiation of IGly, whereas 50 ,m CNQX, a non-NMDA receptor antagonist, did not. The potentiation effect was reduced when NMDA was applied in a Ca2+ -free extracellular solution or in the presence of BAPTA AM, and was independent of the activation of voltage-dependent Ca2+ channels. Pretreatment with KN-62, a selective Ca2+,calmodulin-dependent protein kinase II (CaMKII) inhibitor, abolished the NMDA action. Inhibition of calcineurin (CaN) further enhanced the NMDA-induced potentiation of IGly. In addition, the GABAA receptor-mediated currents were suppressed by NMDA receptor activation in the SDCN neurons. The present results show that Ca2+ entry through NMDA receptors modulates the Gly receptor function via coactivation of CaMKII and CaN in the rat SDCN neurons. This interaction may represent one of the important regulatory mechanisms of spinal nociception. The results also suggest that GABAA and Gly receptors may be subject to different intracellular modulatory pathways. [source]

    Stimulation of fibroblast proliferation by neokyotorphin requires Ca2+ influx and activation of PKA, CaMK II and MAPK/ERK

    FEBS JOURNAL, Issue 2 2007
    Olga V. Sazonova
    Neokyotorphin [TSKYR, hemoglobin ,-chain fragment (137,141)] has previously been shown to enhance fibroblast proliferation, its effect depending on cell density and serum level. Here we show the dependence of the effect of neokyotorphin on cell type and its correlation with the effect of protein kinase A (PKA) activator 8-Br-cAMP, but not the PKC activator 4,-phorbol 12-myristate, 13-acetate (PMA). In L929 fibroblasts, the proliferative effect of neokyotorphin was suppressed by the Ca2+L -type channel inhibitors verapamil or nifedipine, the intracellular Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane- N,N,N,,N, - tetraacetic acid acetoxymethyl ester, kinase inhibitors H-89 (PKA), KN-62 (Ca2+/calmodulin-dependent kinase II) and PD98059 (mitogen-activated protein kinase). The proliferative effect of 8-Br-cAMP was also suppressed by KN-62 and PD98059. PKC suppression (downregulation with PMA or inhibition with bisindolylmaleimide XI) did not affect neokyotorphin action. The results obtained point to a cAMP-like action for neokyotorphin. [source]

    Proteasome-driven turnover of tryptophan hydroxylase is triggered by phosphorylation in RBL2H3 cells, a serotonin producing mast cell line

    FEBS JOURNAL, Issue 19 2002
    Yoshiko Iida
    We previously demonstrated in mast cell lines RBL2H3 and FMA3 that tryptophan hydroxylase (TPH) undergoes very fast turnover driven by 26S-proteasomes [Kojima, M., Oguro, K., Sawabe, K., Iida, Y., Ikeda, R., Yamashita, A., Nakanishi, N. & Hasegawa, H. (2000) J. Biochem (Tokyo) 2000, 127, 121,127]. In the present study, we have examined an involvement of TPH phosphorylation in the rapid turnover, using non-neural TPH. The proteasome-driven degradation of TPH in living cells was accelerated by okadaic acid, a protein phosphatase inhibitor. Incorporation of 32P into a 53-kDa protein, which was judged to be TPH based on autoradiography and Western blot analysis using anti-TPH serum and purified TPH as the size marker, was observed in FMA3 cells only in the presence of both okadaic acid and MG132, inhibitors of protein phosphatase and proteasome, respectively. In a cell-free proteasome system constituted mainly of RBL2H3 cell extracts, degradation of exogenous TPH isolated from mastocytoma P-815 cells was inhibited by protein kinase inhibitors KN-62 and K252a but not by H89. Consistent with the inhibitor specificity, the same TPH was phosphorylated by exogenous Ca2+/calmodulin-dependent protein kinase II in the presence of Ca2+ and calmodulin but not by protein kinase A (catalytic subunit). TPH protein thus phosphorylated by Ca2+/calmodulin-dependent protein kinase II was digested more rapidly in the cell-free proteasome system than was the nonphosphorylated enzyme. These results indicated that the phosphorylation of TPH was a prerequisite for proteasome-driven TPH degradation. [source]

    Differential regulation of CaMKII inhibitor , protein expression after exposure to a novel context and during contextual fear memory formation

    K. Radwa
    Understanding of the molecular basis of long-term fear memory (fear LTM) formation provides targets in the treatment of emotional disorders. Ca2+/calmodulin-dependent protein kinase II (CaMKII) is one of the key synaptic molecules involved in fear LTM formation. There are two endogenous inhibitor proteins of CaMKII, CaMKII N, and N,, which can regulate CaMKII activity in vitro. However, the physiological role of these endogenous inhibitors is not known. Here, we have investigated whether CaMKII N, protein expression is regulated after contextual fear conditioning or exposure to a novel context. Using a novel CaMKII N, -specific antibody, CaMKII N, expression was analysed in the nave mouse brain as well as in the amygdala and hippocampus after conditioning and context exposure. We show that in nave mouse forebrain CaMKII N, protein is expressed at its highest levels in olfactory bulb, prefrontal and piriform cortices, amygdala and thalamus. The protein is expressed both in dendrites and cell bodies. CaMKII N, expression is rapidly and transiently up-regulated in the hippocampus after context exposure. In the amygdala, its expression is regulated only by contextual fear conditioning and not by exposure to a novel context. In conclusion, we show that CaMKII N, expression is differentially regulated by novelty and contextual fear conditioning, providing further insight into molecular basis of fear LTM. [source]

    Handling and environmental enrichment do not rescue learning and memory impairments in ,CamKIIT286A mutant mice

    A. C. Need
    Environmental enrichment and postnatal handling have been shown to improve learning and memory in the Morris water maze, and to rescue impairments caused by genetic modification, age or genetic background. Mice with a targeted point mutation that prevents autophosphorylation at threonine-286 of the ,-isoform of the Ca2+/calmodulin-dependent kinase II have impaired hippocampus-dependent and -independent strategy learning and memory in the water maze. We have investigated whether these impairments can be rescued with a combination of postnatal handling and environmental enrichment in a hybrid genetic background. Severe impairments were seen in acquisition and probe trials in both enriched and nonenriched mutants, indicating that enrichment did not rescue the learning and memory impairments. However, enrichment did rescue a specific performance deficit; enhanced floating behaviour, in the mutants. In summary, we have shown the lack of autophosphorylation of the ,-isoform of the Ca2+/calmodulin-dependent kinase II prevents enrichment-induced rescues of strategy learning and memory impairments. Furthermore, we have established that there are enrichment mechanisms that are independent of this autophosphorylation. [source]

    Mechanisms underlying the inability to induce area CA1 LTP in the mouse after traumatic brain injury

    HIPPOCAMPUS, Issue 6 2006
    E. Schwarzbach
    Abstract Traumatic brain injury (TBI) is a significant health issue that often causes enduring cognitive deficits, in particular memory dysfunction. The hippocampus, a structure crucial in learning and memory, is frequently damaged during TBI. Since long-term potentiation (LTP) is the leading cellular model underlying learning and memory, this study was undertaken to examine how injury affects area CA1 LTP in mice using lateral fluid percussion injury (FPI). Brain slices derived from FPI animals demonstrated an inability to induce LTP in area CA1 7 days postinjury. However, area CA1 long-term depression could be induced in neurons 7 days postinjury, demonstrating that some forms of synaptic plasticity can still be elicited. Using a multidisciplined approach, potential mechanisms underlying the inability to induce and maintain area CA1 LTP were investigated. This study demonstrates that injury leads to significantly smaller N -methyl- D -aspartate potentials and glutamate-induced excitatory currents, increased dendritic spine size, and decreased expression of ,-calcium calmodulin kinase II. These findings may underlie the injury-induced lack of LTP and thus, contribute to cognitive impairments often associated with TBI. Furthermore, these results provide attractive sites for potential therapeutic intervention directed toward alleviating the devastating consequences of human TBI. 2006 Wiley-Liss, Inc. [source]

    Consolidation of CS and US representations in associative fear conditioning

    HIPPOCAMPUS, Issue 5 2004
    Paul W. Frankland
    Abstract Much attention has been paid to the associative processes that are necessary to fuse together representations of the various components of an episodic memory. In the present study, we focus on the processes involved in the formation of lasting representations of the individual components that make up a fear-conditioning episode. In one-trial contextual fear conditioning experiments, weak conditioning to context occurs if the shock is delivered immediately following placement of the animal in a novel conditioning apparatus, a phenomenon known as the immediate shock deficit. We show that the immediate shock deficit in mice may be alleviated by pre-exposure to either the context or shock. In using this approach to temporally dissect a contextual fear-conditioning task into its constituent representational and associative processes, we are able to examine directly the processes that are important for formation of lasting representations of the context conditioned stimulus (CS) or unconditioned stimulus (US). Our data indicate that the formation of a lasting representation of the context or shock engages protein synthesis-dependent processes. Furthermore, genetic disruption of cAMP-responsive element binding protein (CREB), a transcription factor that regulates the synthesis of new proteins required for long-term memory, disrupts the formation of lasting context memories. We go on to show that the stress hormone epinephrine modulates the consolidation of a context memory, and reverses consolidation deficits in the CREB-deficient mice. Finally we show that disrupting either NMDA or calcium/calmodulin-dependent kinase II (CaMKII) function impairs consolidation of context memories. Together, these data suggest that this approach is particularly suited for the characterization of molecular and cellular processes underlying the formation of stimulus representations. 2004 Wiley-Liss, Inc. [source]

    Phosphorylation of Microtubule-associated Protein SB401 from Solanum berthaultii Regulates Its Effect on Microtubules

    Bao-Quan Liu
    Abstract We reported previously that the protein SB401 from Solanum berthaultii binds to and bundles both microtubules and F-actin. In the current study, we investigated the regulation of SB401 activity by its phosphorylation. Our experimental results showed that the phosphorylation of SB401 by casein kinase II (CKII) downregulates the activities of SB401, namely the bundling of microtubules and enhancement of the polymerization of tubulin. However, phosphorylation of SB401 had no observable effect on its bundling of F-actin. Further investigation using extract of potato pollen indicated that a CKII-like kinase may exist in potato pollen. Antibodies against CKII alpha recognized specifically a major band from the pollen extract and the pollen extract was able to phosphorylate the SB401 protein in vitro. The CKII-like kinase showed a similar ability to downregulate the bundling of microtubules. Our experiments demonstrated that phosphorylation plays an important role in the regulation of SB401 activity. We propose that this phosphorylation may regulate the effects of SB401 on microtubules and the actin cytoskeleton. [source]

    CaM kinase II and protein kinase C activations mediate enhancement of long-term potentiation by nefiracetam in the rat hippocampal CA1 region

    Shigeki Moriguchi
    Abstract Nefiracetam is a pyrrolidine-related nootropic drug exhibiting various pharmacological actions such as cognitive-enhancing effect. We previously showed that nefiracetam potentiates NMDA-induced currents in cultured rat cortical neurons. To address questions whether nefiracetam affects NMDA receptor-dependent synaptic plasticity in the hippocampus, we assessed effects of nefiracetam on NMDA receptor-dependent long-term potentiation (LTP) by electrophysiology and LTP-induced phosphorylation of synaptic proteins by immunoblotting analysis. Nefiracetam treatment at 1,1000 nM increased the slope of fEPSPs in a dose-dependent manner. The enhancement was associated with increased phosphorylation of ,-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor through activation of calcium/calmodulin-dependent protein kinase II (CaMKII) without affecting synapsin I phosphorylation. In addition, nefiracetam treatment increased PKC, activity in a bell-shaped dose,response curve which peaked at 10 nM, thereby increasing phosphorylation of myristoylated alanine-rich protein kinase C substrate and NMDA receptor. Nefiracetam treatment did not affect protein kinase A activity. Consistent with the bell-shaped PKC, activation, nefiracetam treatment enhanced LTP in the rat hippocampal CA1 region with the same bell-shaped dose,response curve. Furthermore, nefiracetam-induced LTP enhancement was closely associated with CaMKII and PKC, activation with concomitant increases in phosphorylation of their endogenous substrates except for synapsin I. These results suggest that nefiracetam potentiates AMPA receptor-mediated fEPSPs through CaMKII activation and enhances NMDA receptor-dependent LTP through potentiation of the post-synaptic CaMKII and protein kinase C activities. Together with potentiation of nicotinic acetylcholine receptor function, nefiracetam-enhanced AMPA and NMDA receptor functions likely contribute to improvement of cognitive function. [source]

    Phosphorylation and activation of tryptophan hydroxylase 2: identification of serine-19 as the substrate site for calcium, calmodulin-dependent protein kinase II

    Donald M. Kuhn
    Abstract Tryptophan hydroxylase (TPH) is the initial and rate-limiting enzyme in the biosynthesis of serotonin. TPH was once thought to be a single-gene product but it is now known to exist in two isoforms. TPH1 is found in the periphery and pineal gland whereas TPH2 is expressed specifically in the CNS. Both TPH isoforms are known to be regulated by protein kinase-dependent phosphorylation and the sites of modification of TPH1 by protein kinase A have been identified. While TPH2 is activated by calcium, calmodulin-dependent protein kinase II (CaMKII), the sites at which this isoform is modified are not known. Treatment of wild-type TPH2 with CaMKII followed by mass spectrometry analysis revealed that the enzyme was activated and phosphorylated at a single site, serine-19. Mutagenesis of serine-19 to alanine did not alter the catalytic function of TPH2 but this mutant enzyme was neither activated nor phosphorylated by CaMKII. A phosphopeptide bracketing phosphoserine-19 in TPH2 was used as an antigen to generate polyclonal antibodies against phosphoserine-19. The antibodies are highly specific for phosphoserine-19 in TPH2. The antibodies do not react with wild-type TPH2 or TPH1 and they do not recognize phophoserine-58 or phosphoserine-260 in TPH1. These results establish that activation of TPH2 by CaMKII is mediated by phosphorylation of serine-19 within the regulatory domain of the enzyme. Production of a specific antibody against the CaMKII phosphorylation site in TPH2 represents a valuable tool to advance the study of the mechanisms regulating the function of this important enzyme. [source]

    Activation of phospholipase C pathways by a synthetic chondroitin sulfate-E tetrasaccharide promotes neurite outgrowth of dopaminergic neurons

    Naoki Sotogaku
    Abstract In dopaminergic neurons, chondroitin sulfate (CS) proteoglycans play important roles in neuronal development and regeneration. However, due to the complexity and heterogeneity of CS, the precise structure of CS with biological activity and the molecular mechanisms underlying its influence on dopaminergic neurons are poorly understood. In this study, we investigated the ability of synthetic CS oligosaccharides and natural polysaccharides to promote the neurite outgrowth of mesencephalic dopaminergic neurons and the signaling pathways activated by CS. CS-E polysaccharide, but not CS-A, -C or -D polysaccharide, facilitated the neurite outgrowth of dopaminergic neurons at CS concentrations within the physiological range. The stimulatory effect of CS-E polysaccharide on neurite outgrowth was completely abolished by its digestion into disaccharide units with chondroitinase ABC. Similarly to CS-E polysaccharide, a synthetic tetrasaccharide displaying only the CS-E sulfation motif stimulated the neurite outgrowth of dopaminergic neurons, whereas a CS-E disaccharide or unsulfated tetrasaccharide had no effect. Analysis of the molecular mechanisms revealed that the action of the CS-E tetrasaccharide was mediated through midkine-pleiotrophin/protein tyrosine phosphatase , and brain-derived neurotrophic factor/tyrosine kinase B receptor pathways, followed by activation of the two intracellular phospholipase C (PLC) signaling cascades: PLC/protein kinase C and PLC/inositol 1,4,5-triphosphate/inositol 1,4,5-triphosphate receptor signaling leading to intracellular Ca2+ concentration-dependent activation of Ca2+/calmodulin-dependent kinase II and calcineurin. These results indicate that a specific sulfation motif, in particular the CS-E tetrasaccharide unit, represents a key structural determinant for activation of midkine, pleiotrophin and brain-derived neurotrophic factor-mediated signaling, and is required for the neuritogenic activity of CS in dopaminergic neurons. [source]

    Dopamine D1 and D3 receptors oppositely regulate NMDA- and cocaine-induced MAPK signaling via NMDA receptor phosphorylation

    Hongyuan Jiao
    Abstract Development of drug addiction involves complex molecular changes in the CNS. The mitogen-activated protein kinase (MAPK) signaling pathway plays a key role in mediating neuronal activation induced by dopamine, glutamate, and drugs of abuse. We previously showed that dopamine D1 and D3 receptors play different roles in regulating cocaine-induced MAPK activation. Although there are functional and physical interactions between dopamine and glutamate receptors, little is known regarding the involvement of D1 and D3 receptors in modulating glutamate-induced MAPK activation and underlying mechanisms. In this study, we show that D1 and D3 receptors play opposite roles in regulating N -methyl- d -aspartate (NMDA) -induced activation of extracellular signal-regulated kinase (ERK) in the caudate putamen (CPu). D3 receptors also inhibit NMDA-induced activation of the c-Jun N-terminal kinase and p38 kinase in the CPu. NMDA-induced activation of the NMDA-receptor R1 subunit (NR1), Ca2+/calmodulin-dependent protein kinase II and the cAMP-response element binding protein (CREB), and cocaine-induced CREB activation in the CPu are also oppositely regulated by dopamine D1 and D3 receptors. Finally, the blockade of NMDA-receptor reduces cocaine-induced ERK activation, and inhibits phosphorylation of NR1, Ca2+/calmodulin-dependent protein kinase II, and CREB, while inhibiting ERK activation attenuates cocaine-induced CREB phosphorylation in the CPu. These results suggest that dopamine D1 and D3 receptors oppositely regulate NMDA- and cocaine-induced MAPK signaling via phosphorylation of NR1. [source]

    Regulation of mitogen-activated protein kinases by glutamate receptors

    John Q. Wang
    Abstract Glutamate receptors regulate gene expression in neurons by activating intracellular signaling cascades that phosphorylate transcription factors within the nucleus. The mitogen-activated protein kinase (MAPK) cascade is one of the best characterized cascades in this regulatory process. The Ca2+ -permeable ionotropic glutamate receptor, mainly the NMDA receptor subtype, activates MAPKs through a biochemical route involving the Ca2+ -sensitive Ras-guanine nucleotide releasing factor, Ca2+/calmodulin-dependent protein kinase II, and phosphoinositide 3-kinase. The metabotropic glutamate receptor (mGluR), however, activates MAPKs primarily through a Ca2+ -insensitve pathway involving the transactivation of receptor tyrosine kinases. The adaptor protein Homer also plays a role in this process. As an information superhighway between surface glutamate receptors and transcription factors in the nucleus, active MAPKs phosphorylate specific transcription factors (Elk-1 and CREB), and thereby regulate distinct programs of gene expression. The regulated gene expression contributes to the development of multiple forms of synaptic plasticity related to long-lasting changes in memory function and addictive properties of drugs of abuse. This review, by focusing on new data from recent years, discusses the signaling mechanisms by which different types of glutamate receptors activate MAPKs, features of each MAPK cascade in regulating gene expression, and the importance of glutamate/MAPK-dependent synaptic plasticity in memory and addiction. [source]

    Impaired long-term depression in P2X3 deficient mice is not associated with a spatial learning deficit

    Yue Wang
    Abstract The hippocampus is a brain region critical for learning and memory processes believed to result from long-lasting changes in the function and structure of synapses. Recent findings suggest that ATP functions as a neurotransmitter or neuromodulator in the mammalian brain, where it activates several different types of ionotropic and G protein-coupled ATP receptors that transduce calcium signals. However, the roles of specific ATP receptors in synaptic plasticity have not been established. Here we show that mice lacking the P2X3 ATP receptor (P2X3KO mice) exhibit abnormalities in hippocampal synaptic plasticity that can be restored by pharmacological modification of calcium-sensitive kinase and phosphatase activities. Calcium imaging studies revealed an attenuated calcium response to ATP in hippocampal neurons from P2X3KO mice. Basal synaptic transmission, paired-pulse facilitation and long-term potentiation are normal at synapses in hippocampal slices from P2X3KO. However, long-term depression is severely impaired at CA1, CA3 and dentate gyrus synapses. Long-term depression can be partially rescued in slices treated with a protein phosphatase 1,2 A activator or by postsynaptic inhibition of calcium/calmodulin-dependent protein kinase II. Despite the deficit in hippocampal long-term depression, P2X3KO mice performed normally in water maze tests of spatial learning, suggesting that long-term depression is not critical for this type of hippocampus-dependent learning and memory. [source]

    Identification of the isoforms of Ca2+/calmodulin-dependent protein kinase II and expression of brain-derived neurotrophic factor mRNAs in the substantia nigra

    Akifumi Kamata
    Abstract Ca2+/calmodulin-dependent protein kinase (CaMK)II is highly expressed in the CNS and mediates activity-dependent neuronal plasticity. Four CaMKII isoforms, ,, ,, , and ,, have a large number of splicing variants. Here we identified isoforms of CaMKII in the rat substantia nigra (SN). Northern blot and RT,PCR analyses revealed that the , and , isoform mRNAs with several splicing variants were predominantly expressed in SN. Immunoblot analysis indicated that the major isoforms were ,A, ,C, ,1 and ,3. An immunohistochemical study also confirmed the preferential localization of , and , isoforms in SN dopaminergic neurons. In dopaminergic neurons, immunoreactivity against anti-CaMKII,1,4 antibody was detected in both nucleus and cytoplasm, in contrast to the predominant expression of , isoforms in the cytoplasm. Furthermore, we showed expression of brain-derived neurotrophic factor (BDNF) mRNAs with exons II and IV in SN. Taken together with our previous observations, the results suggest that the CaMKII,3 isoform is involved in the expression of BDNF in the SN. [source]

    Modulation of the Phosphorylation and Activity of Calcium/Calmodulin-Dependent Protein Kinase II by Zinc

    Imre Lengyel
    Calcium/calmodulin-dependent protein kinase II (CaMPK-II) is a key regulatory enzyme in living cells. Modulation of its activity, therefore, could have a major impact on many cellular processes. We found that Zn2+ has multiple functional effects on CaMPK-II. Zn2+ generated a Ca2+/CaM-independent activity that correlated with the autophosphorylation of Thr286, inhibited Ca2+/CaM binding that correlated with the autophosphorylation of Thr306, and inhibited CaMPK-II activity at high concentrations that correlated with the autophosphorylation of Ser279. The relative level of autophosphorylation of these three sites was dependent on the concentration of zinc used. The autophosphorylation of at least these three sites, together with Zn2+ binding, generated an increased mobility form of CaMPK-II on sodium dodecyl sulfate gels. Overall, autophosphorylation induced by Zn2+ converts CaMPK-II into a different form than the binding of Ca2+/CaM. In certain nerve terminals, where Zn2+ has been shown to play a neuromodulatory role and is present in high concentrations, Zn2+ may turn CaMPK-II into a form that would be unable to respond to calcium signals. [source]

    Role of Ca2+/calmodulin-dependent protein kinase II in dendritic spine remodeling during epileptiform activity in vitro

    Xiang-ming Zha
    Abstract Epileptiform activity (EA) in vivo and in vitro induces a loss of dendritic spines and synapses. Because CaMKII has been implicated in synaptogenesis and synaptic plasticity, we investigated the role of CaMKII in the effects of EA on spines, using rat hippocampal slice cultures. To visualize dendrites and postsynaptic densities (PSDs) in pyramidal neurons in the slices, we used biolistic transfection to express either free GFP or a PSD95-YFP construct that specifically labels PSDs. This allowed us to distinguish two classes of dendritic protrusions: spines that contain PSDs, and filopodia that lack PSDs and that are, on average, longer than spines. By these criteria, 48 hr of EA caused a decrease specifically in the number of spines. Immunoblots showed that EA increased CaMKII activity in the slices. Inhibition of CaMKII by expression of AIP, a specific peptide inhibitor of CaMKII, reduced spine number under basal conditions and failed to prevent EA-induced spine loss. However, under EA conditions, AIP increased the number of filopodia and the number of PSDs on the dendritic shaft. These data show at least two roles for CaMKII activity in maintenance and remodeling of dendritic spines under basal or EA conditions. First, CaMKII activity promotes the maintenance of spines and spine PSDs. Second, CaMKII activity suppresses EA-induced formation of filopodia and suppresses an increase in shaft PSDs, apparently by promoting translocation of PSDs from dendritic shafts to spines and/or selectively stabilizing spine rather than shaft PSDs. 2009 Wiley-Liss, Inc. [source]

    The MAPK pathway is required for depolarization-induced "promiscuous" immediate-early gene expression but not for depolarization-restricted immediate-early gene expression in neurons

    Hidevaldo B. Machado
    Abstract Depolarization, growth factors, neurotrophins, and other stimuli induce expression of immediate early genes (IEGs) in neurons. We identified a subset of IEGs, IPD-IEGs, which are induced preferentially by depolarization, but not by neurotrophins or growth factors, in PC12 cells. The "promiscuous" IEGs Egr1 and c-fos, induced by growth factors and neurotrophins, in addition to depolarization, require activation of the MAP kinase signaling pathway for induction in response to KCl depolarization in PC12 cells; MEK1/2 inhibitors block KCl-induced Egr1 and c-fos expression. In contrast, MEK1/2 inhibition has no effect on KCl-induced expression of the known IPD-IEGs in PC12 cells. Additional "candidate" IDP-IEGs were identified by a microarray comparison of genes induced by KCl in the presence vs. the absence of an MEK1/2 inhibitor in PC12 cells. Northern blot analyses demonstrated that representative newly identified candidate IPD-IEGs, as with the known IPD-IEGs, are also induced by a MAP kinase- independent pathway in response to depolarization, both in PC12 cells and in rat primary cortical neurons. Nerve growth factor and epidermal growth factor are unable to induce the expression of the Crem/Icer, Nur77, Nor1, Rgs2, Dusp1 (Mkp1), and Dscr1 genes in PC12 cells, validating their identification as IPD-IEGs. Inhibiting calcium/calmodulin-dependent kinase II (CaMKII), calcineurin, or protein kinase A (PKA) activity prevents KCl-induced IPD-IEG mRNA accumulation, suggesting that the IPD-IEG genes are induced by depolarization in neurons via a combination of calcineurin/PKA- and CaMKII-dependent pathways. 2007 Wiley-Liss, Inc. [source]