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Bell MK, Rangamani P. Crosstalk between biochemical signalling network architecture and trafficking governs AMPAR dynamics in synaptic plasticity. J Physiol 2023. [PMID: 36620889 DOI: 10.1113/jp284029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 01/03/2023] [Indexed: 01/10/2023] Open
Abstract
Synaptic plasticity involves modification of both biochemical and structural components of neurons. Many studies have revealed that the change in the number density of the glutamatergic receptor AMPAR at the synapse is proportional to synaptic weight update; an increase in AMPAR corresponds to strengthening of synapses while a decrease in AMPAR density weakens synaptic connections. The dynamics of AMPAR are thought to be regulated by upstream signalling, primarily the calcium-CaMKII pathway, trafficking to and from the synapse, and influx from extrasynaptic sources. Previous work in the field of deterministic modelling of CaMKII dynamics has assumed bistable kinetics, while experiments and rule-based modelling have revealed that CaMKII dynamics can be either monostable or ultrasensitive. This raises the following question: how does the choice of model assumptions involving CaMKII dynamics influence AMPAR dynamics at the synapse? To answer this question, we have developed a set of models using compartmental ordinary differential equations to systematically investigate contributions of different signalling and trafficking variations, along with their coupled effects, on AMPAR dynamics at the synaptic site. We find that the properties of the model including network architecture describing different stability features of CaMKII and parameters that capture the endocytosis and exocytosis of AMPAR significantly affect the integration of fast upstream species by slower downstream species. Furthermore, we predict that the model outcome, as determined by bound AMPAR at the synaptic site, depends on (1) the choice of signalling model (bistable CaMKII or monostable CaMKII dynamics), (2) trafficking versus influx contributions and (3) frequency of stimulus. KEY POINTS: The density of AMPA receptors (AMPARs) at the postsynaptic density of the synapse provides a readout of synaptic plasticity, which involves crosstalk between complex biochemical signalling networks including CaMKII dynamics and trafficking pathways including exocytosis and endocytosis. Here we build a model that integrates CaMKII dynamics and AMPAR trafficking to explore this crosstalk. We compare different models of CaMKII that result in monostable or bistable kinetics and their impact on AMPAR dynamics. Our results show that AMPAR density depends on the coupling between aspects of biochemical signalling and trafficking. Specifically, assumptions regarding CaMKII dynamics and its stability features can alter AMPAR density at the synapse. Our model also predicts that the kinetics of trafficking versus influx of AMPAR from the extrasynaptic space can further impact AMPAR density. Thus, the contributions of both signalling and trafficking should be considered in computational models.
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Affiliation(s)
- Miriam K Bell
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, USA
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, USA
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2
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Staples MC, Herman MA, Lockner JW, Avchalumov Y, Kharidia KM, Janda KD, Roberto M, Mandyam CD. Isoxazole-9 reduces enhanced fear responses and retrieval in ethanol-dependent male rats. J Neurosci Res 2021; 99:3047-3065. [PMID: 34496069 PMCID: PMC10112848 DOI: 10.1002/jnr.24932] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 06/30/2021] [Accepted: 07/12/2021] [Indexed: 12/13/2022]
Abstract
Plasticity in the dentate gyrus (DG) is strongly influenced by ethanol, and ethanol experience alters long-term memory consolidation dependent on the DG. However, it is unclear if DG plasticity plays a role in dysregulation of long-term memory consolidation during abstinence from chronic ethanol experience. Outbred male Wistar rats experienced 7 weeks of chronic intermittent ethanol vapor exposure (CIE). Seventy-two hours after CIE cessation, CIE and age-matched ethanol-naïve Air controls experienced auditory trace fear conditioning (TFC). Rats were tested for cue-mediated retrieval in the fear context either twenty-four hours (24 hr), ten days (10 days), or twenty-one days (21 days) later. CIE rats showed enhanced freezing behavior during TFC acquisition compared to Air rats. Air rats showed significant fear retrieval, and this behavior did not differ at the three time points. In CIE rats, fear retrieval increased over time during abstinence, indicating an incubation in fear responses. Enhanced retrieval at 21 days was associated with reduced structural and functional plasticity of ventral granule cell neurons (GCNs) and reduced expression of synaptic proteins important for neuronal plasticity. Systemic treatment with the drug Isoxazole-9 (Isx-9; small molecule that stimulates DG plasticity) during the last week and a half of CIE blocked altered acquisition and retrieval of fear memories in CIE rats during abstinence. Concurrently, Isx-9 modulated the structural and functional plasticity of ventral GCNs and the expression of synaptic proteins in the ventral DG. These findings identify that abstinence-induced disruption of fear memory consolidation occurs via altered plasticity within the ventral DG, and that Isx-9 prevented these effects.
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Affiliation(s)
| | - Melissa A. Herman
- Department of Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Jonathan W. Lockner
- Departments of Chemistry and Immunology, Scripps Research, La Jolla, CA, USA
| | | | | | - Kim D. Janda
- Departments of Chemistry and Immunology, Scripps Research, La Jolla, CA, USA
| | - Marisa Roberto
- Departments of Molecular Medicine and Neuroscience, Scripps Research, La Jolla, CA, USA
| | - Chitra D. Mandyam
- VA San Diego Healthcare System, San Diego, CA, USA
- Department of Anesthesiology, University of California San Diego, San Diego, CA, USA
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Sarazin MXB, Victor J, Medernach D, Naudé J, Delord B. Online Learning and Memory of Neural Trajectory Replays for Prefrontal Persistent and Dynamic Representations in the Irregular Asynchronous State. Front Neural Circuits 2021; 15:648538. [PMID: 34305535 PMCID: PMC8298038 DOI: 10.3389/fncir.2021.648538] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 05/31/2021] [Indexed: 11/13/2022] Open
Abstract
In the prefrontal cortex (PFC), higher-order cognitive functions and adaptive flexible behaviors rely on continuous dynamical sequences of spiking activity that constitute neural trajectories in the state space of activity. Neural trajectories subserve diverse representations, from explicit mappings in physical spaces to generalized mappings in the task space, and up to complex abstract transformations such as working memory, decision-making and behavioral planning. Computational models have separately assessed learning and replay of neural trajectories, often using unrealistic learning rules or decoupling simulations for learning from replay. Hence, the question remains open of how neural trajectories are learned, memorized and replayed online, with permanently acting biological plasticity rules. The asynchronous irregular regime characterizing cortical dynamics in awake conditions exerts a major source of disorder that may jeopardize plasticity and replay of locally ordered activity. Here, we show that a recurrent model of local PFC circuitry endowed with realistic synaptic spike timing-dependent plasticity and scaling processes can learn, memorize and replay large-size neural trajectories online under asynchronous irregular dynamics, at regular or fast (sped-up) timescale. Presented trajectories are quickly learned (within seconds) as synaptic engrams in the network, and the model is able to chunk overlapping trajectories presented separately. These trajectory engrams last long-term (dozen hours) and trajectory replays can be triggered over an hour. In turn, we show the conditions under which trajectory engrams and replays preserve asynchronous irregular dynamics in the network. Functionally, spiking activity during trajectory replays at regular timescale accounts for both dynamical coding with temporal tuning in individual neurons, persistent activity at the population level, and large levels of variability consistent with observed cognitive-related PFC dynamics. Together, these results offer a consistent theoretical framework accounting for how neural trajectories can be learned, memorized and replayed in PFC networks circuits to subserve flexible dynamic representations and adaptive behaviors.
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Affiliation(s)
- Matthieu X B Sarazin
- Institut des Systèmes Intelligents et de Robotique, CNRS, Inserm, Sorbonne Université, Paris, France
| | - Julie Victor
- CEA Paris-Saclay, CNRS, NeuroSpin, Saclay, France
| | - David Medernach
- Institut des Systèmes Intelligents et de Robotique, CNRS, Inserm, Sorbonne Université, Paris, France
| | - Jérémie Naudé
- Neuroscience Paris Seine - Institut de biologie Paris Seine, CNRS, Inserm, Sorbonne Université, Paris, France
| | - Bruno Delord
- Institut des Systèmes Intelligents et de Robotique, CNRS, Inserm, Sorbonne Université, Paris, France
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The role of CaMKII autophosphorylation for NMDA receptor-dependent synaptic potentiation. Neuropharmacology 2021; 193:108616. [PMID: 34051268 DOI: 10.1016/j.neuropharm.2021.108616] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 05/01/2021] [Accepted: 05/13/2021] [Indexed: 11/24/2022]
Abstract
Potentiation of glutamatergic synaptic transmission is thought to underlie memory. The induction of this synaptic potentiation relies on activation of NMDA receptors which allows for calcium influx into the post-synapse. A key mechanistic question for the understanding of synaptic potentiation is what signaling is activated by the calcium influx. Here, I review evidences that at mature synapses the elevated calcium levels activate primarily calcium/calmodulin-dependent kinase II (CaMKII) and cause its autophophorylation. CaMKII autophosphorylation leads to calcium-independent activity of the kinase, so that kinase signaling can outlast NMDA receptor-dependent calcium influx. Prolonged CaMKII signaling induces downstream signaling for AMPA receptor trafficking into the post-synaptic density and causes structural enlargement of the synapse. Interestingly, however, CaMKII autophosphorylation does not have such an essential role in NMDA receptor-dependent synaptic potentiation in early postnatal development and in adult dentate gyrus, where neurogenesis occurs. Additionally, in old age memory-relevant NMDA receptor-dependent synaptic plasticity appears to be due to generation of multi-innervated dendritic spines, which does not require CaMKII autophosphorylation. In conclusion, CaMKII autophosphorylation has a conditional role in the induction of NMDA receptor-dependent synaptic potentiation.
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Saneyoshi T. Reciprocal activation within a kinase effector complex: A mechanism for the persistence of molecular memory. Brain Res Bull 2021; 170:58-64. [PMID: 33556559 DOI: 10.1016/j.brainresbull.2021.01.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/10/2021] [Accepted: 01/25/2021] [Indexed: 01/01/2023]
Abstract
Synaptic connections in neuronal circuits change in response to neuronal activity patterns. This can induce a persistent change in the efficacy of synaptic transmission, a phenomenon known as synaptic plasticity. One form of plasticity, long-term potentiation (LTP) has been extensively studied as the cellular basis of memory. In LTP, the potentiated synaptic transmission persists along with structural changes in the synapses. Many studies have sought to identify the "memory molecule" or the "molecular engram". Ca2+/calmodulin-dependent protein kinase II (CaMKII) is probably the most well-studied candidate for the memory molecule. However, consensus has not yet been reached on a very basic aspect: how CaMKII is regulated during LTP. Here, I propose a new model of CaMKII regulation: reciprocal activation within a kinase effector complex (RAKEC) that is made between CaMKII and its effector protein, which is mediated by a persistent interaction between CaMKII and a pseudosubstrate sequence on T-lymphoma invasion and metastasis protein 1 (Tiam1), resulting in reciprocal activation of these two molecules. Through the RAKEC mechanism, CaMKII can maintain memory as biochemical activity in a synapse-specific manner. In this review, the detailed mechanism of the RAKEC and its expansion for the maintenance of LTP is described.
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Affiliation(s)
- Takeo Saneyoshi
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
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Smolen P, Baxter DA, Byrne JH. Comparing Theories for the Maintenance of Late LTP and Long-Term Memory: Computational Analysis of the Roles of Kinase Feedback Pathways and Synaptic Reactivation. Front Comput Neurosci 2020; 14:569349. [PMID: 33390922 PMCID: PMC7772319 DOI: 10.3389/fncom.2020.569349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 11/16/2020] [Indexed: 11/26/2022] Open
Abstract
A fundamental neuroscience question is how memories are maintained from days to a lifetime, given turnover of proteins that underlie expression of long-term synaptic potentiation (LTP) or “tag” synapses as eligible for LTP. A likely solution relies on synaptic positive feedback loops, prominently including persistent activation of Ca2+/calmodulin kinase II (CaMKII) and self-activated synthesis of protein kinase M ζ (PKMζ). Data also suggest positive feedback based on recurrent synaptic reactivation within neuron assemblies, or engrams, is necessary to maintain memories. The relative importance of these mechanisms is controversial. To explore the likelihood that each mechanism is necessary or sufficient to maintain memory, we simulated maintenance of LTP with a simplified model incorporating persistent kinase activation, synaptic tagging, and preferential reactivation of strong synapses, and analyzed implications of recent data. We simulated three model variants, each maintaining LTP with one feedback loop: autonomous, self-activated PKMζ synthesis (model variant I); self-activated CamKII (model variant II); and recurrent reactivation of strengthened synapses (model variant III). Variant I predicts that, for successful maintenance of LTP, either 1) PKMζ contributes to synaptic tagging, or 2) a low constitutive tag level persists during maintenance independent of PKMζ, or 3) maintenance of LTP is independent of tagging. Variant II maintains LTP and suggests persistent CaMKII activation could maintain PKMζ activity, a feedforward interaction not previously considered. However, we note data challenging the CaMKII feedback loop. In Variant III synaptic reactivation drives, and thus predicts, recurrent or persistent activation of CamKII and other necessary kinases, plausibly contributing to persistent elevation of PKMζ levels. Reactivation is thus predicted to sustain recurrent rounds of synaptic tagging and incorporation of plasticity-related proteins. We also suggest (model variant IV) that synaptic reactivation and autonomous kinase activation could synergistically maintain LTP. We propose experiments that could discriminate these maintenance mechanisms.
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Affiliation(s)
- Paul Smolen
- Department of Neurobiology and Anatomy, W.M. Keck Center for the Neurobiology of Learning and Memory, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Douglas A Baxter
- Department of Neurobiology and Anatomy, W.M. Keck Center for the Neurobiology of Learning and Memory, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, TX, United States.,Engineering and Medicine, Texas A&M Health Science Center, Houston, TX, United States
| | - John H Byrne
- Department of Neurobiology and Anatomy, W.M. Keck Center for the Neurobiology of Learning and Memory, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, TX, United States
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Kim CH, Kim S, Kim SH, Roh J, Jin H, Song B. Role of densin-180 in mouse ventral hippocampal neurons in 24-hr retention of contextual fear conditioning. Brain Behav 2020; 10:e01891. [PMID: 33064361 PMCID: PMC7749528 DOI: 10.1002/brb3.1891] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 09/01/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022] Open
Abstract
INTRODUCTION Densin-180 interacts with postsynaptic molecules including calcium/calmodulin-dependent protein kinase IIα (CaMKIIα) but its function in learning and memory process has been unclear. METHODS To investigate a role of hippocampal densin-180 in contextual fear conditioning (CFC) learning and memory processes, knockdown (KD) of densin-180 in hippocampal subareas was applied. RESULTS First, ventral hippocampal (vHC) densin-180 KD impaired single-trial CFC (stCFC) memory one day later. stCFC caused freezing behaviors to reach the peak about one hour later in both control and KD mice, but then freezing was disappeared at 2 hr postshock in KD mice. Second, stCFC caused an immediate and transient reduction of vHC densin-180 in control mice, which was not observed in KD mice. Third, stCFC caused phosphorylated-T286 (p-T286) CaMKIIα to change similarly to densin-180, but p-T305 CaMKIIα was increased 1 hr later in control mice. In KD mice, these effects were gone. Moreover, both basal levels of p-T286 and p-T305 CaMKIIα were reduced without change in total CaMKIIα in KD mice. Fourth, we found double-trial CFC (dtCFC) memory acquisition and retrieval kinetics were different from those of stCFC in vHC KD mice. In addition, densin-180 in dorsal hippocampal area appeared to play its unique role during the very early retrieval period of both CFC memories. CONCLUSION This study shows that vHC densin-180 is necessary for stCFC memory formation and retrieval and suggests that both densin-180 and p-T305 CaMKIIα at 1 ~ 2 hr postshock are important for stCFC memory formation. We conclude that roles of hippocampal neuronal densin-180 in CFC are temporally dynamic and differential depending on the pattern of conditioning stimuli and its location along the dorsoventral axis of hippocampal formation.
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Affiliation(s)
- Chong-Hyun Kim
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Seoyul Kim
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Su-Hyun Kim
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Jongtae Roh
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Harin Jin
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Bokyung Song
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
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8
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Mitchell R, Mikolajczak M, Kersten C, Fleetwood-Walker S. ErbB1-dependent signalling and vesicular trafficking in primary afferent nociceptors associated with hypersensitivity in neuropathic pain. Neurobiol Dis 2020; 142:104961. [DOI: 10.1016/j.nbd.2020.104961] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/26/2020] [Accepted: 06/08/2020] [Indexed: 02/06/2023] Open
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Ordyan M, Bartol T, Kennedy M, Rangamani P, Sejnowski T. Interactions between calmodulin and neurogranin govern the dynamics of CaMKII as a leaky integrator. PLoS Comput Biol 2020; 16:e1008015. [PMID: 32678848 PMCID: PMC7390456 DOI: 10.1371/journal.pcbi.1008015] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 07/29/2020] [Accepted: 06/04/2020] [Indexed: 01/10/2023] Open
Abstract
Calmodulin-dependent kinase II (CaMKII) has long been known to play an important role in learning and memory as well as long term potentiation (LTP). More recently it has been suggested that it might be involved in the time averaging of synaptic signals, which can then lead to the high precision of information stored at a single synapse. However, the role of the scaffolding molecule, neurogranin (Ng), in governing the dynamics of CaMKII is not yet fully understood. In this work, we adopt a rule-based modeling approach through the Monte Carlo method to study the effect of Ca2+ signals on the dynamics of CaMKII phosphorylation in the postsynaptic density (PSD). Calcium surges are observed in synaptic spines during an EPSP and back-propagating action potential due to the opening of NMDA receptors and voltage dependent calcium channels. Using agent-based models, we computationally investigate the dynamics of phosphorylation of CaMKII monomers and dodecameric holoenzymes. The scaffolding molecule, Ng, when present in significant concentration, limits the availability of free calmodulin (CaM), the protein which activates CaMKII in the presence of calcium. We show that Ng plays an important modulatory role in CaMKII phosphorylation following a surge of high calcium concentration. We find a non-intuitive dependence of this effect on CaM concentration that results from the different affinities of CaM for CaMKII depending on the number of calcium ions bound to the former. It has been shown previously that in the absence of phosphatase, CaMKII monomers integrate over Ca2+ signals of certain frequencies through autophosphorylation (Pepke et al, Plos Comp. Bio., 2010). We also study the effect of multiple calcium spikes on CaMKII holoenzyme autophosphorylation, and show that in the presence of phosphatase, CaMKII behaves as a leaky integrator of calcium signals, a result that has been recently observed in vivo. Our models predict that the parameters of this leaky integrator are finely tuned through the interactions of Ng, CaM, CaMKII, and PP1, providing a mechanism to precisely control the sensitivity of synapses to calcium signals. Author Summary not valid for PLOS ONE submissions.
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Affiliation(s)
- Mariam Ordyan
- Institute for Neural Computation, University of California San Diego, La Jolla, California, United States of America
- Computational Neurobiology Laboratory, Salk Institute for Biological Sciences, La Jolla, California, United States of America
| | - Tom Bartol
- Computational Neurobiology Laboratory, Salk Institute for Biological Sciences, La Jolla, California, United States of America
| | - Mary Kennedy
- The Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, United States of America
- * E-mail: (PR), (TS)
| | - Terrence Sejnowski
- Institute for Neural Computation, University of California San Diego, La Jolla, California, United States of America
- Computational Neurobiology Laboratory, Salk Institute for Biological Sciences, La Jolla, California, United States of America
- * E-mail: (PR), (TS)
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Somkuwar SS, Mandyam CD. Individual Differences in Ethanol Drinking and Seeking Behaviors in Rats Exposed to Chronic Intermittent Ethanol Vapor Exposure is Associated with Altered CaMKII Autophosphorylation in the Nucleus Accumbens Shell. Brain Sci 2019; 9:brainsci9120367. [PMID: 31835746 PMCID: PMC6955871 DOI: 10.3390/brainsci9120367] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 11/16/2022] Open
Abstract
Chronic intermittent ethanol vapor exposure (CIE) in rodents produces reliable and high blood ethanol concentration and behavioral symptoms associated with moderate to severe alcohol use disorder (AUD)—for example, escalation of operant ethanol self-administration, a feature suggestive of transition from recreational to addictive use, is a widely replicated behavior in rats that experience CIE. Herein, we present evidence from a subset of rats that do not demonstrate escalation of ethanol self-administration following seven weeks of CIE. These low responders (LR) maintain low ethanol self-administration during CIE, demonstrate lower relapse to drinking during abstinence and reduced reinstatement of ethanol seeking triggered by ethanol cues when compared with high responders (HR). We examined the blood ethanol levels in LR and HR rats during CIE and show higher levels in LR compared with HR. We also examined peak corticosterone levels during CIE and show that LR rats have higher levels compared with HR rats. Lastly, we evaluated the levels of Ca2+/calmodulin-dependent protein kinase II (CaMKII) in the nucleus accumbens shell and reveal that the activity of CaMKII, which is autophosphorylated at site Tyr-286, is significantly reduced in HR rats compared with LR rats. These findings demonstrate that dysregulation of the hypothalamic–pituitary–adrenal axis activity and plasticity-related proteins regulating molecular memory in the nucleus accumbens shell are associated with higher ethanol-drinking and -seeking in HR rats. Future mechanistic studies should evaluate CaMKII autophosphorylation-dependent remodeling of glutamatergic synapses in the ventral striatum as a plausible mechanism for the CIE-induced enhanced ethanol drinking and seeking behaviors.
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Affiliation(s)
| | - Chitra D Mandyam
- VA San Diego Healthcare System, San Diego, CA 92161, USA
- Department of Anesthesiology, University of California San Diego, San Diego, CA 92161, USA
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11
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Jura B. A Mechanism of Synaptic Clock Underlying Subjective Time Perception. Front Neurosci 2019; 13:716. [PMID: 31354421 PMCID: PMC6633209 DOI: 10.3389/fnins.2019.00716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 06/25/2019] [Indexed: 11/13/2022] Open
Abstract
Temporal resolution of visual information processing is thought to be an important factor in predator-prey interactions, shaped in the course of evolution by animals' particular ecology. Here I show that light can be considered to have a dual role of a source of information, which guides motor actions, and an environmental feedback for those actions. I consequently show how temporal perception might depend on feedback-based behavioral adaptations realized in the nervous system through activity-dependent synaptic plasticity. I propose an underlying mechanism of synaptic clock, with every synapse having its characteristic time unit, determined by the persistence of memory traces of synaptic inputs, which is used by the synapse to tell time, and postulate the existence of a specific brain-wide distribution of synaptic clocks with different time units. The present theory offers a simple, testable link between the fields of neurobiology of memory, time perception and ecology, which may account for numerous experimental findings, including the interspecies variation in the temporal resolution and the properties of subjective time perception in humans, specifically the variable speed of perceived time passage, depending on emotional or attentional states or tasks performed.
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Affiliation(s)
- Bartosz Jura
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
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12
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Smolen P, Baxter DA, Byrne JH. How can memories last for days, years, or a lifetime? Proposed mechanisms for maintaining synaptic potentiation and memory. ACTA ACUST UNITED AC 2019; 26:133-150. [PMID: 30992383 PMCID: PMC6478248 DOI: 10.1101/lm.049395.119] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 03/12/2019] [Indexed: 01/24/2023]
Abstract
With memory encoding reliant on persistent changes in the properties of synapses, a key question is how can memories be maintained from days to months or a lifetime given molecular turnover? It is likely that positive feedback loops are necessary to persistently maintain the strength of synapses that participate in encoding. Such feedback may occur within signal-transduction cascades and/or the regulation of translation, and it may occur within specific subcellular compartments or within neuronal networks. Not surprisingly, numerous positive feedback loops have been proposed. Some posited loops operate at the level of biochemical signal-transduction cascades, such as persistent activation of Ca2+/calmodulin kinase II (CaMKII) or protein kinase Mζ. Another level consists of feedback loops involving transcriptional, epigenetic and translational pathways, and autocrine actions of growth factors such as BDNF. Finally, at the neuronal network level, recurrent reactivation of cell assemblies encoding memories is likely to be essential for late maintenance of memory. These levels are not isolated, but linked by shared components of feedback loops. Here, we review characteristics of some commonly discussed feedback loops proposed to underlie the maintenance of memory and long-term synaptic plasticity, assess evidence for and against their necessity, and suggest experiments that could further delineate the dynamics of these feedback loops. We also discuss crosstalk between proposed loops, and ways in which such interaction can facilitate the rapidity and robustness of memory formation and storage.
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Affiliation(s)
- Paul Smolen
- Department of Neurobiology and Anatomy, W. M. Keck Center for the Neurobiology of Learning and Memory, McGovern Medical School of the University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Douglas A Baxter
- Department of Neurobiology and Anatomy, W. M. Keck Center for the Neurobiology of Learning and Memory, McGovern Medical School of the University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - John H Byrne
- Department of Neurobiology and Anatomy, W. M. Keck Center for the Neurobiology of Learning and Memory, McGovern Medical School of the University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
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13
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Bear MF, Cooke SF, Giese KP, Kaang BK, Kennedy MB, Kim JI, Morris RGM, Park P. In memoriam: John Lisman - commentaries on CaMKII as a memory molecule. Mol Brain 2018; 11:76. [PMID: 30593282 PMCID: PMC6309094 DOI: 10.1186/s13041-018-0419-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 10/24/2018] [Indexed: 11/10/2022] Open
Abstract
Shortly before he died in October 2017, John Lisman submitted an invited review to Molecular Brain on 'Criteria for identifying the molecular basis of the engram (CaMKII, PKMζ)'. John had no opportunity to read the referees' comments, and as a mark of the regard in which he was held by the neuroscience community the Editors decided to publish his review as submitted. This obituary takes the form of a series of commentaries on Lisman's review. At the same time we are publishing as a separate article a longer response by Todd Sacktor and André Fenton entitled 'What does LTP tell us about the roles of CaMKII and PKMζ in memory?' which presents the case for a rival memory molecule, PKMζ.
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Affiliation(s)
- Mark F. Bear
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Sam F. Cooke
- King’s College London, Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, De Crespigny Park, London, SE5 8AF UK
| | - Karl Peter Giese
- King’s College London, Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, De Crespigny Park, London, SE5 8AF UK
| | - Bong-Kiun Kaang
- Department of Biological Sciences, Seoul National University, Gwanak-gu, Seoul, Republic of Korea
| | - Mary B. Kennedy
- The Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125 USA
| | - Ji-il Kim
- Department of Biological Sciences, Seoul National University, Gwanak-gu, Seoul, Republic of Korea
| | - Richard G. M. Morris
- Laboratory for Cognitive Neuroscience, Centre for Discovery Brain Sciences, Edinburgh Neuroscience, Edinburgh, EH8 9JZ UK
| | - Pojeong Park
- Department of Biological Sciences, Seoul National University, Gwanak-gu, Seoul, Republic of Korea
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What does LTP tell us about the roles of CaMKII and PKMζ in memory? Mol Brain 2018; 11:77. [PMID: 30593289 PMCID: PMC6309091 DOI: 10.1186/s13041-018-0420-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 10/24/2018] [Indexed: 11/18/2022] Open
Abstract
In “Criteria for identifying the molecular basis of the engram (CaMKII, PKMζ),” Lisman proposes that elucidating the mechanism of LTP maintenance is key to understanding memory storage. He suggests three criteria for a maintenance mechanism to evaluate data on CaMKII and PKMζ as memory storage molecules: necessity, occlusion, and erasure. Here we show that when the criteria are tested, the results reveal important differences between the molecules. Inhibiting PKMζ reverses established, protein synthesis-dependent late-LTP, without affecting early-LTP or baseline synaptic transmission. In contrast, blocking CaMKII has two effects: 1) inhibiting CaMKII activity blocks LTP induction but not maintenance, and 2) disrupting CaMKII interactions with NMDARs in the postsynaptic density (PSD) depresses both early-LTP and basal synaptic transmission equivalently. To identify a maintenance mechanism, we propose a fourth criterion — persistence. PKMζ increases for hours during LTP maintenance in hippocampal slices, and for over a month in specific brain regions during long-term memory storage in conditioned animals. In contrast, increased CaMKII activity lasts only minutes following LTP induction, and CaMKII translocation to the PSD in late-LTP or memory has not been reported. Lastly, do the PKMζ and CaMKII models integrate the many other signaling molecules important for LTP? Activity-dependent PKMζ synthesis is regulated by many of the signaling molecules that induce LTP, including CaMKII, providing a plausible mechanism for new gene expression in the persistent phosphorylation by PKMζ maintaining late-LTP and memory. In contrast, CaMKII autophosphorylation and translocation do not appear to require new protein synthesis. Therefore, the cumulative evidence supports a core role for PKMζ in late-LTP and long-term memory maintenance, and separate roles for CaMKII in LTP induction and for the maintenance of postsynaptic structure and synaptic transmission in a mechanism distinct from late-LTP.
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15
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Vigil FA, Giese KP. Calcium/calmodulin-dependent kinase II and memory destabilization: a new role in memory maintenance. J Neurochem 2018; 147:12-23. [PMID: 29704430 PMCID: PMC6221169 DOI: 10.1111/jnc.14454] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/28/2018] [Accepted: 04/17/2018] [Indexed: 02/03/2023]
Abstract
In this review, we discuss the poorly explored role of calcium/calmodulin-dependent protein kinase II (CaMKII) in memory maintenance, and its influence on memory destabilization. After a brief review on CaMKII and memory destabilization, we present critical pieces of evidence suggesting that CaMKII activity increases retrieval-induced memory destabilization. We then proceed to propose two potential molecular pathways to explain the association between CaMKII activation and increased memory destabilization. This review will pinpoint gaps in our knowledge and discuss some 'controversial' observations, establishing the basis for new experiments on the role of CaMKII in memory reconsolidation. The role of CaMKII in memory destabilization is of great clinical relevance. Still, because of the lack of scientific literature on the subject, more basic science research is necessary to pursue this pathway as a clinical tool.
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Affiliation(s)
- Fabio Antonio Vigil
- Department of Cell and Integrative PhysiologyThe University of Texas Health San Antonio8403, Floyd Curl DriveSan AntonioTX 78229USA
| | - Karl Peter Giese
- Department of Basic and Clinical NeuroscienceKing's College London125 Coldharbour LaneLondonSE5 9NUUK
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16
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Nakahata Y, Yasuda R. Plasticity of Spine Structure: Local Signaling, Translation and Cytoskeletal Reorganization. Front Synaptic Neurosci 2018; 10:29. [PMID: 30210329 PMCID: PMC6123351 DOI: 10.3389/fnsyn.2018.00029] [Citation(s) in RCA: 133] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/07/2018] [Indexed: 12/31/2022] Open
Abstract
Dendritic spines are small protrusive structures on dendritic surfaces, and function as postsynaptic compartments for excitatory synapses. Plasticity of spine structure is associated with many forms of long-term neuronal plasticity, learning and memory. Inside these small dendritic compartments, biochemical states and protein-protein interactions are dynamically modulated by synaptic activity, leading to the regulation of protein synthesis and reorganization of cytoskeletal architecture. This in turn causes plasticity of structure and function of the spine. Technical advances in monitoring molecular behaviors in single dendritic spines have revealed that each signaling pathway is differently regulated across multiple spatiotemporal domains. The spatial pattern of signaling activity expands from a single spine to the nearby dendritic area, dendritic branch and the nucleus, regulating different cellular events at each spatial scale. Temporally, biochemical events are typically triggered by short Ca2+ pulses (~10–100 ms). However, these signals can then trigger activation of downstream protein cascades that can last from milliseconds to hours. Recent imaging studies provide many insights into the biochemical processes governing signaling events of molecular assemblies at different spatial localizations. Here, we highlight recent findings of signaling dynamics during synaptic plasticity and discuss their roles in long-term structural plasticity of dendritic spines.
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Affiliation(s)
- Yoshihisa Nakahata
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience (MPFI), Jupiter, FL, United States
| | - Ryohei Yasuda
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience (MPFI), Jupiter, FL, United States
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17
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Galinato MH, Takashima Y, Fannon MJ, Quach LW, Morales Silva RJ, Mysore KK, Terranova MJ, Dutta RR, Ostrom RW, Somkuwar SS, Mandyam CD. Neurogenesis during Abstinence Is Necessary for Context-Driven Methamphetamine-Related Memory. J Neurosci 2018; 38:2029-2042. [PMID: 29363584 PMCID: PMC5824740 DOI: 10.1523/jneurosci.2011-17.2018] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 12/05/2017] [Accepted: 01/09/2018] [Indexed: 12/22/2022] Open
Abstract
Abstinence from methamphetamine addiction enhances proliferation and differentiation of neural progenitors and increases adult neurogenesis in the dentate gyrus (DG). We hypothesized that neurogenesis during abstinence contributes to context-driven drug-seeking behaviors. To test this hypothesis, the pharmacogenetic rat model (GFAP-TK rats) was used to conditionally and specifically ablate neurogenesis in the DG. Male GFAP-TK rats were trained to self-administer methamphetamine or sucrose and were administered the antiviral drug valganciclovir (Valcyte) to produce apoptosis of actively dividing GFAP type 1 stem-like cells to inhibit neurogenesis during abstinence. Hippocampus tissue was stained for Ki-67, NeuroD, and DCX to measure levels of neural progenitors and immature neurons, and was stained for synaptoporin to determine alterations in mossy fiber tracts. DG-enriched tissue punches were probed for CaMKII to measure alterations in plasticity-related proteins. Whole-cell patch-clamp recordings were performed in acute brain slices from methamphetamine naive (controls) and methamphetamine experienced animals (+/-Valcyte). Spontaneous EPSCs and intrinsic excitability were recorded from granule cell neurons (GCNs). Reinstatement of methamphetamine seeking enhanced autophosphorylation of CaMKII, reduced mossy fiber density, and induced hyperexcitability of GCNs. Inhibition of neurogenesis during abstinence prevented context-driven methamphetamine seeking, and these effects correlated with reduced autophosphorylation of CaMKII, increased mossy fiber density, and reduced the excitability of GCNs. Context-driven sucrose seeking was unaffected. Together, the loss-of-neurogenesis data demonstrate that neurogenesis during abstinence assists with methamphetamine context-driven memory in rats, and that neurogenesis during abstinence is essential for the expression of synaptic proteins and plasticity promoting context-driven drug memory.SIGNIFICANCE STATEMENT Our work uncovers a mechanistic relationship between neurogenesis in the dentate gyrus and drug seeking. We report that the suppression of excessive neurogenesis during abstinence from methamphetamine addiction by a confirmed phamacogenetic approach blocked context-driven methamphetamine reinstatement and prevented maladaptive changes in expression and activation of synaptic proteins and basal synaptic function associated with learning and memory in the dentate gyrus. Our study is the first to demonstrate an interesting and dysfunctional role of adult hippocampal neurogenesis during abstinence to drug-seeking behavior in animals self-administering escalating amounts of methamphetamine. Together, these results support a direct role for the importance of adult neurogenesis during abstinence in compulsive-like drug reinstatement.
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Affiliation(s)
- Melissa H Galinato
- Departments of Neuroscience
- Veterans Medical Research Foundation, VA San Diego Healthcare System, San Diego, California 92161, and
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California 92037
| | - Yoshio Takashima
- Anesthesiology, University of California San Diego, San Diego, California 92093
- Veterans Medical Research Foundation, VA San Diego Healthcare System, San Diego, California 92161, and
| | - McKenzie J Fannon
- Veterans Medical Research Foundation, VA San Diego Healthcare System, San Diego, California 92161, and
| | - Leon W Quach
- Veterans Medical Research Foundation, VA San Diego Healthcare System, San Diego, California 92161, and
| | | | - Karthik K Mysore
- Veterans Medical Research Foundation, VA San Diego Healthcare System, San Diego, California 92161, and
| | - Michael J Terranova
- Veterans Medical Research Foundation, VA San Diego Healthcare System, San Diego, California 92161, and
| | - Rahul R Dutta
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California 92037
| | - Ryan W Ostrom
- Veterans Medical Research Foundation, VA San Diego Healthcare System, San Diego, California 92161, and
| | - Sucharita S Somkuwar
- Veterans Medical Research Foundation, VA San Diego Healthcare System, San Diego, California 92161, and
| | - Chitra D Mandyam
- Departments of Neuroscience,
- Anesthesiology, University of California San Diego, San Diego, California 92093
- Veterans Medical Research Foundation, VA San Diego Healthcare System, San Diego, California 92161, and
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California 92037
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18
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Juárez-Muñoz Y, Ramos-Languren LE, Escobar ML. CaMKII Requirement for in Vivo Insular Cortex LTP Maintenance and CTA Memory Persistence. Front Pharmacol 2017; 8:822. [PMID: 29184500 PMCID: PMC5694558 DOI: 10.3389/fphar.2017.00822] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/30/2017] [Indexed: 12/12/2022] Open
Abstract
Calcium-calmodulin/dependent protein kinase II (CaMKII) plays an essential role in LTP induction, but since it has the capacity to remain persistently activated even after the decay of external stimuli it has been proposed that it can also be necessary for LTP maintenance and therefore for memory persistence. It has been shown that basolateral amygdaloid nucleus (Bla) stimulation induces long-term potentiation (LTP) in the insular cortex (IC), a neocortical region implicated in the acquisition and retention of conditioned taste aversion (CTA). Our previous studies have demonstrated that induction of LTP in the Bla-IC pathway before CTA training increased the retention of this task. Although it is known that IC-LTP induction and CTA consolidation share similar molecular mechanisms, little is known about the molecular actors that underlie their maintenance. The purpose of the present study was to evaluate the role of CaMKII in the maintenance of in vivo Bla-IC LTP as well as in the persistence of CTA long-term memory (LTM). Our results show that acute microinfusion of myr-CaMKIINtide, a selective inhibitor of CaMKII, in the IC of adult rats during the late-phase of in vivo Bla-IC LTP blocked its maintenance. Moreover, the intracortical inhibition of CaMKII 24 h after CTA acquisition impairs CTA-LTM persistence. Together these results indicate that CaMKII is a central key component for the maintenance of neocortical synaptic plasticity as well as for persistence of CTA-LTM.
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Affiliation(s)
- Yectivani Juárez-Muñoz
- División de Investigación y Estudios de Posgrado, Facultad de Psicología, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Laura E Ramos-Languren
- División de Investigación y Estudios de Posgrado, Facultad de Psicología, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Martha L Escobar
- División de Investigación y Estudios de Posgrado, Facultad de Psicología, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
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19
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Rossetti T, Banerjee S, Kim C, Leubner M, Lamar C, Gupta P, Lee B, Neve R, Lisman J. Memory Erasure Experiments Indicate a Critical Role of CaMKII in Memory Storage. Neuron 2017; 96:207-216.e2. [PMID: 28957669 DOI: 10.1016/j.neuron.2017.09.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 07/24/2017] [Accepted: 09/11/2017] [Indexed: 12/29/2022]
Abstract
The abundant synaptic protein CaMKII is necessary for long-term potentiation (LTP) and memory. However, whether CaMKII is required only during initial processes or whether it also mediates memory storage remains unclear. The most direct test of a storage role is the erasure test. In this test, a putative memory molecule is inhibited after learning. The key prediction is that this should produce persistent memory erasure even after the inhibitory agent is removed. We conducted this test using transient viral (HSV) expression of dominant-negative CaMKII-alpha (K42M) in the hippocampus. This produced persistent erasure of conditioned place avoidance. As an additional test, we found that expression of activated CaMKII (T286D/T305A/T306A) impaired place avoidance, a result not expected if a process other than CaMKII stores memory. Our behavioral results, taken together with prior experiments on LTP, strongly support a critical role of CaMKII in LTP maintenance and memory storage.
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Affiliation(s)
- Tom Rossetti
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA
| | - Somdeb Banerjee
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA
| | - Chris Kim
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA
| | - Megan Leubner
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA
| | - Casey Lamar
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA
| | - Pooja Gupta
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA
| | - Bomsol Lee
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA
| | - Rachael Neve
- Gene Delivery Technology Core, Department of Neurology, MGH, 65 Landsdowne Street, Cambridge, MA 02139, USA
| | - John Lisman
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA.
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20
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Kula J, Gugula A, Blasiak A, Bobula B, Danielewicz J, Kania A, Tylko G, Hess G. Diverse action of repeated corticosterone treatment on synaptic transmission, neuronal plasticity, and morphology in superficial and deep layers of the rat motor cortex. Pflugers Arch 2017; 469:1519-1532. [PMID: 28748319 PMCID: PMC5629232 DOI: 10.1007/s00424-017-2036-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 07/12/2017] [Accepted: 07/13/2017] [Indexed: 12/02/2022]
Abstract
One of the adverse effects of prolonged stress in rats is impaired performance of skilled reaching and walking tasks. The mechanisms that lead to these abnormalities are incompletely understood. Therefore, we compared the effects of twice daily repeated corticosterone injections for 7 days on miniature excitatory postsynaptic currents (mEPSCs), as well as on synaptic plasticity and morphology of layers II/III and V pyramidal neurons of the primary motor cortex (M1) of male Wistar rats. Corticosterone treatment resulted in increased frequency, but not amplitude, of mEPSCs in layer II/III neurons accompanied by increased complexity of the apical part of their dendritic tree, with no changes in the density of dendritic spines. The frequency and amplitude of mEPSCs as well as the parameters characterizing the complexity of the dendritic tree were not changed in layer V cells; however, their dendritic spine density was increased. While corticosterone treatment resulted in an increase in the amplitude of field potentials evoked in intralaminar connections within layer II/III, it did not influence field responses in layer V intralaminar connections, as well as the extent of chemically induced layer V long-term potentiation (chemLTP) by the application of tetraethylammonium (TEA, 25 mM). However, chemLTP induction in layer II/III was impaired in slices prepared from corticosterone-treated animals. These data indicate that repeated 7-day administration of exogenous corticosterone induces structural and functional plasticity in the M1, which occurs mainly in layer II/III pyramidal neurons. These findings shed light on potential sites of action and mechanisms underlying stress-induced impairment of motor functions.
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Affiliation(s)
- Joanna Kula
- Institute of Zoology and Biomedical Research, Jagiellonian University, 30-387 Krakow, Gronostajowa 9, Poland
| | - Anna Gugula
- Institute of Zoology and Biomedical Research, Jagiellonian University, 30-387 Krakow, Gronostajowa 9, Poland
| | - Anna Blasiak
- Institute of Zoology and Biomedical Research, Jagiellonian University, 30-387 Krakow, Gronostajowa 9, Poland
| | - Bartosz Bobula
- Institute of Zoology and Biomedical Research, Jagiellonian University, 30-387 Krakow, Gronostajowa 9, Poland.,Institute of Pharmacology, Polish Academy of Sciences, 31-343 Krakow, Smetna 12, Poland
| | - Joanna Danielewicz
- Institute of Zoology and Biomedical Research, Jagiellonian University, 30-387 Krakow, Gronostajowa 9, Poland
| | - Alan Kania
- Institute of Zoology and Biomedical Research, Jagiellonian University, 30-387 Krakow, Gronostajowa 9, Poland
| | - Grzegorz Tylko
- Institute of Zoology and Biomedical Research, Jagiellonian University, 30-387 Krakow, Gronostajowa 9, Poland
| | - Grzegorz Hess
- Institute of Zoology and Biomedical Research, Jagiellonian University, 30-387 Krakow, Gronostajowa 9, Poland. .,Institute of Pharmacology, Polish Academy of Sciences, 31-343 Krakow, Smetna 12, Poland.
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21
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CaMKII Autophosphorylation Is Necessary for Optimal Integration of Ca 2+ Signals during LTP Induction, but Not Maintenance. Neuron 2017; 94:800-808.e4. [PMID: 28521133 DOI: 10.1016/j.neuron.2017.04.041] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 02/17/2017] [Accepted: 04/27/2017] [Indexed: 01/26/2023]
Abstract
CaMKII plays a critical role in decoding calcium (Ca2+) signals to initiate long-lasting synaptic plasticity. However, the properties of CaMKII that mediate Ca2+ signals in spines remain elusive. Here, we measured CaMKII activity in spines using fast-framing two-photon fluorescence lifetime imaging. Following each pulse during repetitive Ca2+ elevations, CaMKII activity increased in a stepwise manner. Thr286 phosphorylation slows the decay of CaMKII and thus lowers the frequency required to induce spine plasticity by several fold. In the absence of Thr286 phosphorylation, increasing the stimulation frequency results in high peak mutant CaMKIIT286A activity that is sufficient for inducing plasticity. Our findings demonstrate that Thr286 phosphorylation plays an important role in induction of LTP by integrating Ca2+ signals, and it greatly promotes, but is dispensable for, the activation of CaMKII and LTP.
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22
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Murakoshi H, Shin ME, Parra-Bueno P, Szatmari EM, Shibata ACE, Yasuda R. Kinetics of Endogenous CaMKII Required for Synaptic Plasticity Revealed by Optogenetic Kinase Inhibitor. Neuron 2017; 94:37-47.e5. [PMID: 28318784 DOI: 10.1016/j.neuron.2017.02.036] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 11/25/2016] [Accepted: 02/17/2017] [Indexed: 01/12/2023]
Abstract
Elucidating temporal windows of signaling activity required for synaptic and behavioral plasticity is crucial for understanding molecular mechanisms underlying these phenomena. Here, we developed photoactivatable autocamtide inhibitory peptide 2 (paAIP2), a genetically encoded, light-inducible inhibitor of CaMKII activity. The photoactivation of paAIP2 in neurons for 1-2 min during the induction of LTP and structural LTP (sLTP) of dendritic spines inhibited these forms of plasticity in hippocampal slices of rodents. However, photoactivation ∼1 min after the induction did not affect them, suggesting that the initial 1 min of CaMKII activation is sufficient for inducing LTP and sLTP. Furthermore, the photoactivation of paAIP2 expressed in amygdalar neurons of mice during an inhibitory avoidance task revealed that CaMKII activity during, but not after, training is required for the memory formation. Thus, we demonstrated that paAIP2 is useful to elucidate the temporal window of CaMKII activation required for synaptic plasticity and learning.
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Affiliation(s)
- Hideji Murakoshi
- Supportive Center for Brain Research, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan; Department of Physiological Sciences, Graduate University for Advanced Studies, Okazaki, Aichi 444-8585, Japan; Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan; Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
| | - Myung Eun Shin
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - Paula Parra-Bueno
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | | | - Akihiro C E Shibata
- Supportive Center for Brain Research, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan
| | - Ryohei Yasuda
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA; Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA.
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23
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Shetty MS, Sajikumar S. Differential involvement of Ca 2+/calmodulin-dependent protein kinases and mitogen-activated protein kinases in the dopamine D1/D5 receptor-mediated potentiation in hippocampal CA1 pyramidal neurons. Neurobiol Learn Mem 2016; 138:111-120. [PMID: 27470093 DOI: 10.1016/j.nlm.2016.07.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 07/21/2016] [Accepted: 07/23/2016] [Indexed: 10/21/2022]
Abstract
Dopaminergic neurotransmission modulates and influences hippocampal CA1 synaptic plasticity, learning and long-term memory mechanisms. Investigating the mechanisms involved in the slow-onset potentiation induced by the dopamine D1/D5 receptor agonists in hippocampal CA1 region, we have reported recently that it could play a role in regulating synaptic cooperation and competition. We have also shown that a sustained activation of MEK/MAP kinase pathway was involved in the maintenance of this long-lasting potentiation (Shivarama Shetty, Gopinadhan, & Sajikumar, 2016). However, the molecular aspects of the induction of dopaminergic slow-onset potentiation are not known. Here, we investigated the involvement of MEK/MAPK pathway and Ca2+-calmodulin-dependent protein kinases (CaMKII and CaMKIV) in the induction and maintenance phases of the D1/D5 receptor-mediated slow-onset potentiation. We report differential involvement of these kinases in a dose-dependent manner wherein at weaker levels of dopaminergic activation, both CaMKII and MEK1/2 activation is necessary for the establishment of potentiation and with sufficiently stronger dopaminergic activation, the role of CaMKII becomes dispensable whereas MEK activation remains crucial for the long-lasting potentiation. The results are interesting in view of the involvement of the hippocampal dopaminergic system in a variety of cognitive abilities including memory formation and also in neurological diseases such as Alzheimer's disease and Parkinson's disease.
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Affiliation(s)
- Mahesh Shivarama Shetty
- Department of Physiology, Block MD9, 2 Medical Drive, Yong Loo Lin School of Medicine, National University of Singapore, 117597, Singapore; Neurobiology/Aging Program, 28 Medical Drive, Life Sciences Institute, National University of Singapore, Singapore
| | - Sreedharan Sajikumar
- Department of Physiology, Block MD9, 2 Medical Drive, Yong Loo Lin School of Medicine, National University of Singapore, 117597, Singapore; Neurobiology/Aging Program, 28 Medical Drive, Life Sciences Institute, National University of Singapore, Singapore.
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24
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Ghosh A, Giese KP. Calcium/calmodulin-dependent kinase II and Alzheimer's disease. Mol Brain 2015; 8:78. [PMID: 26603284 PMCID: PMC4657223 DOI: 10.1186/s13041-015-0166-2] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 11/13/2015] [Indexed: 11/10/2022] Open
Abstract
CaMKII is a remarkably complex protein kinase, known to have a fundamental role in synaptic plasticity and memory formation. Further, CaMKII has also been suggested to be a tau kinase. CaMKII dysregulation may therefore be a modulator of toxicity in Alzheimer's disease, a dementia characterised by aberrant calcium signalling, synapse and neuronal loss, and impaired memory. Here, we first examine the evidence for CaMKII dysregulation in Alzheimer's patients and draw parallels to findings in disease models which recapitulate key aspects of the disease. We then put forward the hypothesis that these changes critically contribute to neurodegeneration and memory impairment in Alzheimer's disease.
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Affiliation(s)
- Anshua Ghosh
- Maurice Wohl Clinical Neuroscience Institute, King's College London, 5 Cutcombe Road, London, SE5 9RT, UK.
| | - Karl Peter Giese
- Maurice Wohl Clinical Neuroscience Institute, King's College London, 5 Cutcombe Road, London, SE5 9RT, UK.
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25
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Michalski PJ. First demonstration of bistability in CaMKII, a memory-related kinase. Biophys J 2014; 106:1233-5. [PMID: 24655498 DOI: 10.1016/j.bpj.2014.01.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 01/29/2014] [Indexed: 11/28/2022] Open
Affiliation(s)
- Paul J Michalski
- Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, Connecticut.
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Villers A, Giese KP, Ris L. Long-term potentiation can be induced in the CA1 region of hippocampus in the absence of αCaMKII T286-autophosphorylation. ACTA ACUST UNITED AC 2014; 21:616-26. [PMID: 25322797 PMCID: PMC4201817 DOI: 10.1101/lm.035972.114] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
α-calcium/calmodulin-dependent protein kinase (αCaMKII) T286-autophosphorylation provides a short-term molecular memory that was thought to be required for LTP and for learning and memory. However, it has been shown that learning can occur in αCaMKII-T286A mutant mice after a massed training protocol. This raises the question of whether there might be a form of LTP in these mice that can occur without T286 autophosphorylation. In this study, we confirmed that in CA1 pyramidal cells, LTP induced in acute hippocampal slices, after a recovery period in an interface chamber, is strictly dependent on postsynaptic αCaMKII autophosphorylation. However, we demonstrated that αCaMKII-autophosphorylation-independent plasticity can occur in the hippocampus but at the expense of synaptic specificity. This nonspecific LTP was observed in mutant and wild-type mice after a recovery period in a submersion chamber and was independent of NMDA receptors. Moreover, when slices prepared from mutant mice were preincubated during 2 h with rapamycin, high-frequency trains induced a synapse-specific LTP which was added to the nonspecific LTP. This specific LTP was related to an increase in the duration and the amplitude of NMDA receptor-mediated response induced by rapamycin.
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Affiliation(s)
- Agnès Villers
- Department of Neuroscience, Research Institute for Biosciences, University of Mons, B-7000 Mons, Belgium
| | - Karl Peter Giese
- MRC Centre for Neurodegeneration, Institute of Psychiatry, King's College London, SE5 9NU, London, United Kingdom
| | - Laurence Ris
- Department of Neuroscience, Research Institute for Biosciences, University of Mons, B-7000 Mons, Belgium
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Stein IS, Donaldson MS, Hell JW. CaMKII binding to GluN2B is important for massed spatial learning in the Morris water maze. F1000Res 2014; 3:193. [PMID: 25187880 PMCID: PMC4149248 DOI: 10.12688/f1000research.4660.1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/08/2014] [Indexed: 12/17/2022] Open
Abstract
Learning and memory as well as long-term potentiation (LTP) depend on Ca
2+ influx through the NMDA-type glutamate receptor (NMDAR) and the resulting activation of the Ca
2+ and calmodulin-dependent protein kinase (CaMKII). Ca
2+ influx via the NMDAR triggers CaMKII binding to the NMDAR for enhanced CaMKII accumulation at post-synaptic sites that experience heightened activity as occurring during LTP. Previously, we generated knock-in (KI) mice in which we replaced two residues in the NMDAR GluN2B subunit to impair CaMKII binding to GluN2B. Various forms of LTP at the Schaffer collateral synapses in CA1 are reduced by 50%. Nevertheless, working memory in the win-shift 8 arm maze and learning of the Morris water maze (MWM) task was normal in the KI mice although recall of the task was impaired in these mice during the period of early memory consolidation. We now show that massed training in the MWM task within a single day resulted in impaired learning. However, learning and recall of the Barnes maze task and contextual fear conditioning over one or multiple days were surprisingly unaffected. The differences observed in the MWM compared to the Barnes maze and contextual fear conditioning suggest a differential involvement of CaMKII and the specific interaction with GluN2B, probably depending on varying degrees of stress, cognitive demand or even potentially different plasticity mechanisms associated with the diverse tasks.
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Affiliation(s)
- Ivar S Stein
- Department of Pharmacology, School of Medicine, University of California, Davis, 95616-8636, USA
| | - Michaela S Donaldson
- Department of Pharmacology, School of Medicine, University of California, Davis, 95616-8636, USA
| | - Johannes W Hell
- Department of Pharmacology, School of Medicine, University of California, Davis, 95616-8636, USA
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Barcomb K, Buard I, Coultrap SJ, Kulbe JR, O'Leary H, Benke TA, Bayer KU. Autonomous CaMKII requires further stimulation by Ca2+/calmodulin for enhancing synaptic strength. FASEB J 2014; 28:3810-9. [PMID: 24843070 DOI: 10.1096/fj.14-250407] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A hallmark feature of Ca(2+)/calmodulin (CaM)-dependent protein kinase II (CaMKII) is generation of autonomous (Ca(2+)-independent) activity by T286 autophosphorylation. Biochemical studies have shown that "autonomous" CaMKII is ∼5-fold further stimulated by Ca(2+)/CaM, but demonstration of a physiological function for such regulation within cells has remained elusive. In this study, CaMKII-induced enhancement of synaptic strength in rat hippocampal neurons required both autonomous activity and further stimulation. Synaptic strength was decreased by CaMKIIα knockdown and rescued by reexpression, but not by mutants impaired for autonomy (T286A) or binding to NMDA-type glutamate receptor subunit 2B (GluN2B; formerly NR2B; I205K). Full rescue was seen with constitutively autonomous mutants (T286D), but only if they could be further stimulated (additional T305/306A mutation), and not with two other mutations that additionally impair Ca(2+)/CaM binding. Compared to rescue with wild-type CaMKII, the CaM-binding-impaired mutants even had reduced synaptic strength. One of these mutants (T305/306D) mimicked an inhibitory autophosphorylation of CaMKII, whereas the other one (Δstim) abolished CaM binding without introducing charged residues. Inhibitory T305/306 autophosphorylation also reduced GluN2B binding, but this effect was independent of reduced Ca(2+)/CaM binding and was not mimicked by T305/306D mutation. Thus, even autonomous CaMKII activity must be further stimulated by Ca(2+)/CaM for enhancement of synaptic strength.
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Affiliation(s)
| | | | | | | | - Heather O'Leary
- Department of Pharmacology and Department of Pediatrics, Section of Neurology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Timothy A Benke
- Department of Pharmacology and Department of Pediatrics, Section of Neurology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
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29
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Michalski PJ. The delicate bistability of CaMKII. Biophys J 2014; 105:794-806. [PMID: 23931327 DOI: 10.1016/j.bpj.2013.06.038] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 06/13/2013] [Accepted: 06/25/2013] [Indexed: 01/08/2023] Open
Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) is a synaptic, autophosphorylating kinase that is essential for learning and memory. Previous models have suggested that CaMKII functions as a bistable switch that could be the molecular correlate of long-term memory, but experiments have failed to validate these predictions. These models involved significant approximations to overcome the combinatorial complexity inherent in a multisubunit, multistate system. Here, we develop a stochastic particle-based model of CaMKII activation and dynamics that overcomes combinatorial complexity without significant approximations. We report four major findings. First, the CaMKII model system is never bistable at resting calcium concentrations, which suggests that CaMKII activity does not function as the biochemical switch underlying long-term memory. Second, the steady-state activation curves are either laserlike or steplike. Both are characterized by a well-defined threshold for activation, which suggests that thresholding is a robust feature of this system. Third, transiently activated CaMKII can maintain its activity over the time course of many experiments, and such slow deactivation may account for the few reports of bistability in the literature. And fourth, under in vivo conditions, increases in phosphatase activity can increase CaMKII activity. This is a surprising and counterintuitive effect, as dephosphorylation is generally associated with CaMKII deactivation.
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Affiliation(s)
- P J Michalski
- Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, Connecticut, USA.
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30
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Nonaka M, Fujii H, Kim R, Kawashima T, Okuno H, Bito H. Untangling the two-way signalling route from synapses to the nucleus, and from the nucleus back to the synapses. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130150. [PMID: 24298152 DOI: 10.1098/rstb.2013.0150] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
During learning and memory, it has been suggested that the coordinated electrical activity of hippocampal neurons translates information about the external environment into internal neuronal representations, which then are stored initially within the hippocampus and subsequently into other areas of the brain. A widely held hypothesis posits that synaptic plasticity is a key feature that critically modulates the triggering and the maintenance of such representations, some of which are thought to persist over time as traces or tags. However, the molecular and cell biological basis for these traces and tags has remained elusive. Here, we review recent findings that help clarify some of the molecular and cellular mechanisms critical for these events, by untangling a two-way signalling crosstalk route between the synapses and the neuronal soma. In particular, a detailed interrogation of the soma-to-synapse delivery of immediate early gene product Arc/Arg3.1, whose induction is triggered by heightened synaptic activity in many brain areas, teases apart an unsuspected 'inverse' synaptic tagging mechanism that likely contributes to maintaining the contrast of synaptic weight between strengthened and weak synapses within an active ensemble.
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Affiliation(s)
- Mio Nonaka
- Department of Neurochemistry, Graduate School of Medicine, University of Tokyo, , Bunkyo-ku, Tokyo 113-0033, Japan
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31
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Fujii H, Inoue M, Okuno H, Sano Y, Takemoto-Kimura S, Kitamura K, Kano M, Bito H. Nonlinear decoding and asymmetric representation of neuronal input information by CaMKIIα and calcineurin. Cell Rep 2013; 3:978-87. [PMID: 23602566 DOI: 10.1016/j.celrep.2013.03.033] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 03/18/2013] [Accepted: 03/20/2013] [Indexed: 10/26/2022] Open
Abstract
How information encoded in glutamate release rates at individual synapses is converted into biochemical activation patterns of postsynaptic enzymes remains unexplored. To address this, we developed a dual fluorescence resonance energy transfer (FRET) imaging platform and recorded CaMKIIα and calcineurin activities in hippocampal neurons while varying glutamate uncaging frequencies. With little spine morphological change, 5 Hz spine glutamate uncaging strongly stimulated calcineurin, but not CaMKIIα. In contrast, 20 Hz spine glutamate uncaging, which induced spine growth, activated both CaMKIIα and calcineurin with distinct spatiotemporal kinetics. Higher temporal resolution recording in the soma revealed that CaMKIIα activity summed supralinearly and sensed both higher frequency and input number, thus acting as an input frequency/number decoder. In contrast, calcineurin activity summated sublinearly with increasing input number and showed little frequency dependence, thus functioning as an input number counter. These results provide evidence that CaMKIIα and calcineurin are fine-tuned to unique bandwidths and compute input variables in an asymmetric manner.
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Affiliation(s)
- Hajime Fujii
- Department of Neurochemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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33
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Bradykinin-induced chemotaxis of human gliomas requires the activation of KCa3.1 and ClC-3. J Neurosci 2013; 33:1427-40. [PMID: 23345219 DOI: 10.1523/jneurosci.3980-12.2013] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Previous reports demonstrate that cell migration in the nervous system is associated with stereotypic changes in intracellular calcium concentration ([Ca(2+)](i)), yet the target of these changes are essentially unknown. We examined chemotactic migration/invasion of human gliomas to study how [Ca(2+)](i) regulates cellular movement and to identify downstream targets. Gliomas are primary brain cancers that spread exclusively within the brain, frequently migrating along blood vessels to which they are chemotactically attracted by bradykinin. Using simultaneous fura-2 Ca(2+) imaging and amphotericin B perforated patch-clamp electrophysiology, we find that bradykinin raises [Ca(2+)](i) and induces a biphasic voltage response. This voltage response is mediated by the coordinated activation of Ca(2+)-dependent, TRAM-34-sensitive K(Ca)3.1 channels, and Ca(2+)-dependent, 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS)-sensitive and gluconate-sensitive Cl(-) channels. A significant portion of these Cl(-) currents can be attributed to Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) activation of ClC-3, a voltage-gated Cl(-) channel/transporter, because pharmacological inhibition of CaMKII or shRNA-mediated knockdown of ClC-3 inhibited Ca(2+)-activated Cl(-) currents. Western blots show that K(Ca)3.1 and ClC-3 are expressed in tissue samples obtained from patients diagnosed with grade IV gliomas. Both K(Ca)3.1 and ClC-3 colocalize to the invading processes of glioma cells. Importantly, inhibition of either channel abrogates bradykinin-induced chemotaxis and reduces tumor expansion in mouse brain slices in situ. These channels should be further explored as future targets for anti-invasive drugs. Furthermore, these data elucidate a novel mechanism placing cation and anion channels downstream of ligand-mediated [Ca(2+)](i) increases, which likely play similar roles in other migratory cells in the nervous system.
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34
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On the mechanism of synaptic depression induced by CaMKIIN, an endogenous inhibitor of CaMKII. PLoS One 2012; 7:e49293. [PMID: 23145145 PMCID: PMC3493544 DOI: 10.1371/journal.pone.0049293] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Accepted: 10/08/2012] [Indexed: 12/16/2022] Open
Abstract
Activity-dependent synaptic plasticity underlies, at least in part, learning and memory processes. NMDA receptor (NMDAR)-dependent long-term potentiation (LTP) is a major synaptic plasticity model. During LTP induction, Ca2+/calmodulin-dependent protein kinase II (CaMKII) is activated, autophosphorylated and persistently translocated to the postsynaptic density, where it binds to the NMDAR. If any of these steps is inhibited, LTP is disrupted. The endogenous CaMKII inhibitor proteins CaMKIINα,β are rapidly upregulated in specific brain regions after learning. We recently showed that transient application of peptides derived from CaMKIINα (CN peptides) persistently depresses synaptic strength and reverses LTP saturation, as it allows further LTP induction in previously saturated pathways. The treatment disrupts basal CaMKII-NMDAR interaction and decreases bound CaMKII fraction in spines. To unravel CaMKIIN function and to further understand CaMKII role in synaptic strength maintenance, here we more deeply investigated the mechanism of synaptic depression induced by CN peptides (CN-depression) in rat hippocampal slices. We showed that CN-depression does not require glutamatergic synaptic activity or Ca2+ signaling, thus discarding unspecific triggering of activity-dependent long-term depression (LTD) in slices. Moreover, occlusion experiments revealed that CN-depression and NMDAR-LTD have different expression mechanisms. We showed that CN-depression does not involve complex metabolic pathways including protein synthesis or proteasome-mediated degradation. Remarkably, CN-depression cannot be resolved in neonate rats, for which CaMKII is mostly cytosolic and virtually absent at the postsynaptic densities. Overall, our results support a direct effect of CN peptides on synaptic CaMKII-NMDAR binding and suggest that CaMKIINα,β could be critical plasticity-related proteins that may operate as cell-wide homeostatic regulators preventing saturation of LTP mechanisms or may selectively erase LTP-induced traces in specific groups of synapses.
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35
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Yasuda R. Studying signal transduction in single dendritic spines. Cold Spring Harb Perspect Biol 2012; 4:cshperspect.a005611. [PMID: 22843821 DOI: 10.1101/cshperspect.a005611] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Many forms of synaptic plasticity are triggered by biochemical signaling that occurs in small postsynaptic compartments called dendritic spines, each of which typically houses the postsynaptic terminal associated with a single glutamatergic synapse. Recent advances in optical techniques allow investigators to monitor biochemical signaling in single dendritic spines and thus reveal the signaling mechanisms that link synaptic activity and the induction of synaptic plasticity. This is mostly in the study of Ca2+-dependent forms of synaptic plasticity for which many of the steps between Ca2+ influx and changes to the synapse are now known. This article introduces the new techniques used to investigate signaling in single dendritic spines and the neurobiological insights that they have produced.
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Affiliation(s)
- Ryohei Yasuda
- Neurobiology Department, Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710, USA.
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36
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Coultrap SJ, Bayer KU. CaMKII regulation in information processing and storage. Trends Neurosci 2012; 35:607-18. [PMID: 22717267 DOI: 10.1016/j.tins.2012.05.003] [Citation(s) in RCA: 246] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 05/07/2012] [Accepted: 05/11/2012] [Indexed: 11/29/2022]
Abstract
The Ca(2+)/Calmodulin(CaM)-dependent protein kinase II (CaMKII) is activated by Ca(2+)/CaM, but becomes partially autonomous (Ca(2+)-independent) upon autophosphorylation at T286. This hallmark feature of CaMKII regulation provides a form of molecular memory and is indeed important in long-term potentiation (LTP) of excitatory synapse strength and memory formation. However, emerging evidence supports a direct role in information processing, while storage of synaptic information may instead be mediated by regulated interaction of CaMKII with the NMDA receptor (NMDAR) complex. These and other CaMKII regulation mechanisms are discussed here in the context of the kinase structure and their impact on postsynaptic functions. Recent findings also implicate CaMKII in long-term depression (LTD), as well as functional roles at inhibitory synapses, lending renewed emphasis on better understanding the spatiotemporal control of CaMKII regulation.
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Affiliation(s)
- Steven J Coultrap
- Department of Pharmacology, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
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37
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The role of metaplasticity mechanisms in regulating memory destabilization and reconsolidation. Neurosci Biobehav Rev 2012; 36:1667-707. [PMID: 22484475 DOI: 10.1016/j.neubiorev.2012.03.008] [Citation(s) in RCA: 144] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 03/09/2012] [Accepted: 03/21/2012] [Indexed: 12/13/2022]
Abstract
Memory allows organisms to predict future events based on prior experiences. This requires encoded information to persist once important predictors are extracted, while also being modifiable in response to changes within the environment. Memory reconsolidation may allow stored information to be modified in response to related experience. However, there are many boundary conditions beyond which reconsolidation may not occur. One interpretation of these findings is that the event triggering memory retrieval must contain new information about a familiar stimulus in order to induce reconsolidation. Presently, the mechanisms that affect the likelihood of reconsolidation occurring under these conditions are not well understood. Here we speculate on a number of systems that may play a role in protecting memory from being destabilized during retrieval. We conclude that few memories may enter a state in which they cannot be modified. Rather, metaplasticity mechanisms may serve to alter the specific reactivation cues necessary to destabilize a memory. This might imply that destabilization mechanisms can differ depending on learning conditions.
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38
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Christian DT, Alexander NJ, Diaz MR, Robinson S, McCool BA. Chronic intermittent ethanol and withdrawal differentially modulate basolateral amygdala AMPA-type glutamate receptor function and trafficking. Neuropharmacology 2012; 62:2430-9. [PMID: 22387532 DOI: 10.1016/j.neuropharm.2012.02.017] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 02/15/2012] [Accepted: 02/16/2012] [Indexed: 12/19/2022]
Abstract
The amygdala plays a critical role in the generation and expression of anxiety-like behaviors including those expressed following withdrawal (WD) from chronic intermittent ethanol (CIE) exposure. In particular, the BLA glutamatergic system controls the expression of both innate and pathological anxiety. Recent data suggests that CIE and WD may functionally alter this system in a manner that closely parallels memory-related phenomena like long-term potentiation (LTP). We therefore specifically dissected CIE/WD-induced changes in glutamatergic signaling using electrophysiological and biochemical approaches with a particular focus on the plasticity-related components of this neurotransmitter system. Our results indicate that cortical glutamatergic inputs arriving at BLA principal via the external capsule undergo predominantly post-synaptic alterations in AMPA receptor function following CIE and WD. Biochemical analysis revealed treatment-dependent changes in AMPA receptor surface expression and subunit phosphorylation that are complemented by changes in total protein levels and/or phosphorylation status of several key, plasticity-associated protein kinases such as calcium/calmodulin-dependent protein kinase II (CaMKII) and protein kinase C (PKC). Together, these data show that CIE- and WD-induced changes in BLA glutamatergic function both functionally and biochemically mimic plasticity-related states. These mechanisms likely contribute to long-term increases in anxiety-like behavior following chronic ethanol exposure.
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Affiliation(s)
- Daniel T Christian
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
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39
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Lisman J, Yasuda R, Raghavachari S. Mechanisms of CaMKII action in long-term potentiation. Nat Rev Neurosci 2012; 13:169-82. [PMID: 22334212 DOI: 10.1038/nrn3192] [Citation(s) in RCA: 797] [Impact Index Per Article: 66.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Long-term potentiation (LTP) of synaptic strength occurs during learning and can last for long periods, making it a probable mechanism for memory storage. LTP induction results in calcium entry, which activates calcium/calmodulin-dependent protein kinase II (CaMKII). CaMKII subsequently translocates to the synapse, where it binds to NMDA-type glutamate receptors and produces potentiation by phosphorylating principal and auxiliary subunits of AMPA-type glutamate receptors. These processes are all localized to stimulated spines and account for the synapse-specificity of LTP. In the later stages of LTP, CaMKII has a structural role in enlarging and strengthening the synapse.
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Affiliation(s)
- John Lisman
- Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA.
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40
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Abstract
Synaptic plasticity, or changes in synaptic strength, is thought to underlie learning and memory. Imaging studies, mainly in brain slices, have revealed that long-term synaptic plasticity of excitatory synapses in hippocampal neurons is coupled with structural plasticity of dendritic spines, which is thought to be essential for inducing and regulating functional plasticity. Using pharmacological and genetic manipulation, the signalling network underlying structural plasticity has been extensively studied. Furthermore, the recent advent of fluorescence resonance energy transfer (FRET) imaging techniques has provided a readout of the dynamics of signal transduction in dendritic spines undergoing structural plasticity. These studies reveal the signalling pathways relaying Ca2+ to the functional and structural plasticity of dendritic spines.
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Affiliation(s)
- Michael Patterson
- Department of Neurobiology, Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
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41
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Klug J, Deutch A, Colbran R, Winder D. Synaptic Triad in the Neostriatum. DOPAMINE – GLUTAMATE INTERACTIONS IN THE BASAL GANGLIA 2011. [DOI: 10.1201/b11284-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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42
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Abstract
During long-term potentiation (LTP), synapses undergo stable changes in synaptic strength. The molecular memory processes that maintain strength have not been identified. One hypothesis is that the complex formed by the Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and the NMDA-type glutamate receptor (NMDAR) is a molecular memory at the synapse. To establish a molecule as a molecular memory, it must be shown that interfering with the molecule produces a persistent reversal of LTP. We used the CN class of peptides that inhibit CaMKII binding to the NR2B subunit in vitro to test this prediction in rat hippocampal slices. We found that CN peptides can reverse saturated LTP, allowing additional LTP to be induced. The peptide also produced a persistent reduction in basal transmission. We then tested whether CN compounds actually affect CaMKII binding in living cells. Application of CN peptide to slice cultures reduced the amount of CaMKII concentrated in spines, consistent with delocalization of the kinase from a binding partner in the spine. To more specifically assay the binding of CaMKII to the NMDAR, we used coimmunoprecipitation methods. We found that CN peptide decreased synaptic strength only at concentrations necessary to disrupt the CaMKII/NMDAR complex, but not at lower concentrations sufficient to inhibit CaMKII activity. Importantly, both the reduction of the complex and the reduction of synaptic strength persisted after removal of the inhibitor. These results support the hypothesis that the CaMKII/NMDAR complex has switch-like properties that are important in the maintenance of synaptic strength.
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43
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Easton AC, Lucchesi W, Schumann G, Giese KP, Müller CP, Fernandes C. αCaMKII autophosphorylation controls exploratory activity to threatening novel stimuli. Neuropharmacology 2011; 61:1424-31. [PMID: 21903107 DOI: 10.1016/j.neuropharm.2011.08.036] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Revised: 08/17/2011] [Accepted: 08/20/2011] [Indexed: 02/07/2023]
Abstract
Autophosphorylation of αCaMKII is regarded as a 'molecular memory' for Ca(2+) transients and a crucial mechanism in aversely, but less so in appetitively, motivated learning and memory. While there is a growing body of research implicating αCaMKII in general in behavioral responses to threat or fearful stimuli, little is known about the contribution of the autophosphorylation. The present study asked how αCaMKII autophosphorylation controls anxiety-like behavioral responses toward novel, potentially threatening stimuli. We tested homozygous and heterozygous T286A αCaMKII autophosphorylation deficient mice and wild types in a systematic series of behavioral tests. Homozygous mutants were more active in the open field test and showed reduced anxiety-related behavior in the light/dark test, but these findings were confounded by a hyperlocomotor phenotype. The analysis of elevated plus maze showed significantly reduced anxiety-related behavior in the αCaMKII autophosphorylation-deficient mice which appeared to mediate a hyperlocomotor response. An analysis of home cage behavior, where neither novel nor threatening stimuli were present, showed no differences in locomotor activity between genotypes. Increased locomotion was not observed in the novel object exploration test in the αCaMKII autophosphorylation-deficient mice, implying that hyperactivity does not occur in response to discrete novel stimuli. The present data suggest that the behavior of αCaMKII autophosphorylation-deficient mice cannot simply be described as a low anxiety phenotype. Instead it is suggested that αCaMKII autophosphorylation influences locomotor reactivity to novel environments that are potentially, but not necessarily threatening.
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Affiliation(s)
- Alanna C Easton
- MRC Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College London, De Crespigny Park, London SE5 8AF, UK
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44
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Quantitative estimates of the cytoplasmic, PSD, and NMDAR-bound pools of CaMKII in dendritic spines. Brain Res 2011; 1419:46-52. [PMID: 21925648 DOI: 10.1016/j.brainres.2011.08.051] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 08/17/2011] [Accepted: 08/19/2011] [Indexed: 02/02/2023]
Abstract
CaMKII plays a critical role in long-term potentiation (LTP). The kinase is a major component of the postsynaptic density (PSD); however, it is also contained in the spine cytoplasm. CaMKII can now be monitored optically in living neurons, and it is therefore important to understand the contribution of the PSD and cytoplasmic pools to optical signals. Here, we estimate the size of these pools under basal conditions. From EM immunolabeling data, we calculate that the PSD/cytoplasmic ratio is ~5%. A second independent estimate is derived from measurements indicating that the average mushroom spine PSD contains 90 to 240 holoenzymes. A cytoplasmic concentration of 16 μM (~2590 holoenzymes) in the spine can be estimated from the total measured CaMKII content of hippocampal tissue, the relative volume of different compartments, and the spine-dendrite ratio of CaMKII (2:1). These numbers yield a second estimate (6%) of the PSD/spine ratio in good agreement with the first. The CaMKII bound to the NMDAR is important because preventing the formation of this complex blocks LTP induction. We estimate that the percentage of spine CaMKII held active by binding to the NMDAR is ~0.2%. Implications of the high spine concentration of CaMKII (> 100 μM alpha subunits) and the small fraction within the PSD are discussed. Of particular note, the finding that the CaMKII signal in spines shows only transient activation (open state) after LTP induction is subject to the qualification that it does not reflect the small but important pool bound to the NMDAR.
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Molnár E. Long-term potentiation in cultured hippocampal neurons. Semin Cell Dev Biol 2011; 22:506-13. [PMID: 21807105 DOI: 10.1016/j.semcdb.2011.07.017] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 06/23/2011] [Accepted: 07/01/2011] [Indexed: 10/18/2022]
Abstract
Studies performed on low-density primary neuronal cultures have enabled dissection of molecular and cellular changes during N-methyl-D-aspartate (NMDA) receptor-dependent long-term potentiation (LTP). Various electrophysiological and chemical induction protocols were developed for the persistent enhancement of excitatory synaptic transmission in hippocampal neuronal cultures. The characterisation of these plasticity models confirmed that they share many key properties with the LTP of CA1 neurons, extensively studied in hippocampal slices using electrophysiological techniques. For example, LTP in dissociated hippocampal neuronal cultures is also dependent on Ca(2+) influx through post-synaptic NMDA receptors, subsequent activation and autophosphorylation of the Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and an increase in alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor insertion at the post-synaptic membrane. The availability of models of LTP in cultured hippocampal neurons significantly facilitated the monitoring of changes in endogenous postsynaptic receptor proteins and the investigation of the associated signalling mechanisms that underlie LTP. A central feature of LTP of excitatory synapses is the recruitment of AMPA receptors at the postsynaptic site. Results from the use of cell culture-based models started to establish the mechanism by which synaptic input controls a neuron's ability to modify its synapses in LTP. This review focuses on key features of various LTP induction protocols in dissociated hippocampal neuronal cultures and the applications of these plasticity models for the investigation of activity-induced changes in native AMPA receptors.
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Affiliation(s)
- Elek Molnár
- MRC Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol, UK.
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Lucchesi W, Mizuno K, Giese KP. Novel insights into CaMKII function and regulation during memory formation. Brain Res Bull 2011; 85:2-8. [DOI: 10.1016/j.brainresbull.2010.10.009] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 10/15/2010] [Accepted: 10/29/2010] [Indexed: 01/17/2023]
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Appleby VJ, Corrêa SAL, Duckworth JK, Nash JE, Noël J, Fitzjohn SM, Collingridge GL, Molnár E. LTP in hippocampal neurons is associated with a CaMKII-mediated increase in GluA1 surface expression. J Neurochem 2011; 116:530-43. [PMID: 21143596 DOI: 10.1111/j.1471-4159.2010.07133.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The use of hippocampal dissociated neuronal cultures has enabled the study of molecular changes in endogenous native proteins associated with long-term potentiation. Using immunofluorescence labelling of the active (Thr286-phosphorylated) alpha-Ca(2+) /calmodulin-dependent protein kinase II (CaMKII) we found that CaMKII activity was increased by transient (3 × 1 s) depolarisation in 18- to 21-day-old cultures but not in 9- to 11-day-old cultures. The increase in Thr286 phosphorylation of CaMKII required the activation of NMDA receptors and was greatly attenuated by the CaMKII inhibitor KN-62. We compared the effects of transient depolarisation on the surface expression of GluA1 and GluA2 subunits of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor and found a preferential recruitment of the GluA1 subunit. CaMKII inhibition prevented this NMDA receptor-dependent delivery of GluA1 to the cell surface. CaMKII activation is therefore an important factor in the activity-dependent recruitment of native GluA1 subunit-containing alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors to the cell surface of hippocampal neurons.
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Affiliation(s)
- Vanessa J Appleby
- MRC Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, Bristol, UK
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Bliss TVP, Cooke SF. Long-term potentiation and long-term depression: a clinical perspective. Clinics (Sao Paulo) 2011; 66 Suppl 1:3-17. [PMID: 21779718 PMCID: PMC3118435 DOI: 10.1590/s1807-59322011001300002] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 04/01/2011] [Indexed: 12/24/2022] Open
Abstract
Long-term potentiation and long-term depression are enduring changes in synaptic strength, induced by specific patterns of synaptic activity, that have received much attention as cellular models of information storage in the central nervous system. Work in a number of brain regions, from the spinal cord to the cerebral cortex, and in many animal species, ranging from invertebrates to humans, has demonstrated a reliable capacity for chemical synapses to undergo lasting changes in efficacy in response to a variety of induction protocols. In addition to their physiological relevance, long-term potentiation and depression may have important clinical applications. A growing insight into the molecular mechanisms underlying these processes, and technological advances in non-invasive manipulation of brain activity, now puts us at the threshold of harnessing long-term potentiation and depression and other forms of synaptic, cellular and circuit plasticity to manipulate synaptic strength in the human nervous system. Drugs may be used to erase or treat pathological synaptic states and non-invasive stimulation devices may be used to artificially induce synaptic plasticity to ameliorate conditions arising from disrupted synaptic drive. These approaches hold promise for the treatment of a variety of neurological conditions, including neuropathic pain, epilepsy, depression, amblyopia, tinnitus and stroke.
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Graupner M, Brunel N. Mechanisms of induction and maintenance of spike-timing dependent plasticity in biophysical synapse models. Front Comput Neurosci 2010; 4. [PMID: 20948584 PMCID: PMC2953414 DOI: 10.3389/fncom.2010.00136] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 08/25/2010] [Indexed: 01/02/2023] Open
Abstract
We review biophysical models of synaptic plasticity, with a focus on spike-timing dependent plasticity (STDP). The common property of the discussed models is that synaptic changes depend on the dynamics of the intracellular calcium concentration, which itself depends on pre- and postsynaptic activity. We start by discussing simple models in which plasticity changes are based directly on calcium amplitude and dynamics. We then consider models in which dynamic intracellular signaling cascades form the link between the calcium dynamics and the plasticity changes. Both mechanisms of induction of STDP (through the ability of pre/postsynaptic spikes to evoke changes in the state of the synapse) and of maintenance of the evoked changes (through bistability) are discussed.
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Affiliation(s)
- Michael Graupner
- Center for Neural Science, New York University New York City, NY, USA
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Nakano T, Doi T, Yoshimoto J, Doya K. A kinetic model of dopamine- and calcium-dependent striatal synaptic plasticity. PLoS Comput Biol 2010; 6:e1000670. [PMID: 20169176 PMCID: PMC2820521 DOI: 10.1371/journal.pcbi.1000670] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Accepted: 01/07/2010] [Indexed: 11/28/2022] Open
Abstract
Corticostriatal synapse plasticity of medium spiny neurons is regulated by glutamate input from the cortex and dopamine input from the substantia nigra. While cortical stimulation alone results in long-term depression (LTD), the combination with dopamine switches LTD to long-term potentiation (LTP), which is known as dopamine-dependent plasticity. LTP is also induced by cortical stimulation in magnesium-free solution, which leads to massive calcium influx through NMDA-type receptors and is regarded as calcium-dependent plasticity. Signaling cascades in the corticostriatal spines are currently under investigation. However, because of the existence of multiple excitatory and inhibitory pathways with loops, the mechanisms regulating the two types of plasticity remain poorly understood. A signaling pathway model of spines that express D1-type dopamine receptors was constructed to analyze the dynamic mechanisms of dopamine- and calcium-dependent plasticity. The model incorporated all major signaling molecules, including dopamine- and cyclic AMP-regulated phosphoprotein with a molecular weight of 32 kDa (DARPP32), as well as AMPA receptor trafficking in the post-synaptic membrane. Simulations with dopamine and calcium inputs reproduced dopamine- and calcium-dependent plasticity. Further in silico experiments revealed that the positive feedback loop consisted of protein kinase A (PKA), protein phosphatase 2A (PP2A), and the phosphorylation site at threonine 75 of DARPP-32 (Thr75) served as the major switch for inducing LTD and LTP. Calcium input modulated this loop through the PP2B (phosphatase 2B)-CK1 (casein kinase 1)-Cdk5 (cyclin-dependent kinase 5)-Thr75 pathway and PP2A, whereas calcium and dopamine input activated the loop via PKA activation by cyclic AMP (cAMP). The positive feedback loop displayed robust bi-stable responses following changes in the reaction parameters. Increased basal dopamine levels disrupted this dopamine-dependent plasticity. The present model elucidated the mechanisms involved in bidirectional regulation of corticostriatal synapses and will allow for further exploration into causes and therapies for dysfunctions such as drug addiction. Recent brain imaging and neurophysiological studies suggest that the striatum, the start of the basal ganglia circuit, plays a major role in value-based decision making and behavioral disorders such as drug addiction. The plasticity of synaptic input from the cerebral cortex to output neurons of the striatum, which are medium spiny neurons, depends on interactions between glutamate input from the cortex and dopaminergic input from the midbrain. It also links sensory and cognitive states in the cortex with reward-oriented action outputs. The mechanisms involved in molecular cascades that transmit glutamate and dopamine inputs to changes in postsynaptic glutamate receptors are very complex and it is difficult to intuitively understand the mechanism. Therefore, a biochemical network model was constructed, and computer simulations were performed. The model reproduced dopamine-dependent and calcium-dependent forms of long-term depression (LTD) and potentiation (LTP) of corticostriatal synapses. Further in silico experiments revealed that a positive feedback loop formed by proteins, the protein specifically expressed in the striatum, served as the major switch for inducing LTD and LTP. This model could allow us to understand dynamic constraints in reward-dependent learning, as well as causes and therapies of dopamine-related disorders such as drug addiction.
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Affiliation(s)
- Takashi Nakano
- Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Japan
- Okinawa Institute of Science and Technology, Uruma, Japan
| | | | - Junichiro Yoshimoto
- Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Japan
- Okinawa Institute of Science and Technology, Uruma, Japan
| | - Kenji Doya
- Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Japan
- Okinawa Institute of Science and Technology, Uruma, Japan
- * E-mail:
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