1
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Yao J, Chen SRW. RyR2-dependent modulation of neuronal hyperactivity: A potential therapeutic target for treating Alzheimer's disease. J Physiol 2024; 602:1509-1518. [PMID: 36866974 DOI: 10.1113/jp283824] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 02/27/2023] [Indexed: 03/04/2023] Open
Abstract
Increasing evidence suggests that simply reducing β-amyloid (Aβ) plaques may not significantly affect the progression of Alzheimer's disease (AD). There is also increasing evidence indicating that AD progression is driven by a vicious cycle of soluble Aβ-induced neuronal hyperactivity. In support of this, it has recently been shown that genetically and pharmacologically limiting ryanodine receptor 2 (RyR2) open time prevents neuronal hyperactivity, memory impairment, dendritic spine loss and neuronal cell death in AD mouse models. By contrast, increased RyR2 open probability (Po) exacerbates the onset of familial AD-associated neuronal dysfunction and induces AD-like defects in the absence of AD-causing gene mutations. Thus, RyR2-dependent modulation of neuronal hyperactivity represents a promising new target for combating AD.
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Affiliation(s)
- Jinjing Yao
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - S R Wayne Chen
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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2
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Kim HJ, Ko EA, Kwon OB, Jung SC. Prenatal treatment with corticosterone via maternal injection induces learning and memory impairments via delaying postsynaptic development in hippocampal CA1 neurons of rats. J Neurosci Res 2024; 102:e25323. [PMID: 38553948 DOI: 10.1002/jnr.25323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 02/16/2024] [Accepted: 03/10/2024] [Indexed: 04/02/2024]
Abstract
Previously, we reported that prenatal exposure to high corticosterone induced attention-deficit hyperactivity disorder (ADHD)-like behaviors with cognitive deficits after weaning. In the present study, cellular mechanisms underlying cortisol-induced cognitive dysfunction were investigated using rat pups (Corti.Pups) born from rat mothers that were repetitively injected with corticosterone during pregnancy. In results, Corti.Pups exhibited the failure of behavioral memory formation in the Morris water maze (MWM) test and the incomplete long-term potentiation (LTP) of hippocampal CA1 neurons. Additionally, glutamatergic excitatory postsynaptic currents (EPSCs) were remarkably suppressed in Corti.Pups compared to normal rat pups. Incomplete LTP and weaker EPSCs in Corti.Pups were attributed to the delayed postsynaptic development of CA1 neurons, showing a higher expression of NR2B subunits and lower expression of PSD-95 and BDNF. These results indicated that the prenatal treatment with corticosterone to elevate cortisol level might potently downregulate the BDNF-mediated signaling critical for the synaptic development of hippocampal CA1 neurons during brain development, and subsequently, induce learning and memory impairment. Our findings suggest a possibility that the prenatal dysregulation of cortisol triggers the epigenetic pathogenesis of neurodevelopmental psychiatric disorders, such as ADHD and autism.
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Affiliation(s)
- Hye-Ji Kim
- Department of Physiology, College of Medicine, Jeju National University, Jeju, Republic of Korea
| | - Eun-A Ko
- Department of Physiology, College of Medicine, Jeju National University, Jeju, Republic of Korea
| | - Oh-Bin Kwon
- New Drug Development Center, Kmedihub, Daegu, Republic of Korea
| | - Sung-Cherl Jung
- Department of Physiology, College of Medicine, Jeju National University, Jeju, Republic of Korea
- Institute of Medical Science, Jeju National University, Jeju, Republic of Korea
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3
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Hiess F, Yao J, Song Z, Sun B, Zhang Z, Huang J, Chen L, Institoris A, Estillore JP, Wang R, Ter Keurs HEDJ, Stys PK, Gordon GR, Zamponi GW, Ganguly A, Chen SRW. Subcellular localization of hippocampal ryanodine receptor 2 and its role in neuronal excitability and memory. Commun Biol 2022; 5:183. [PMID: 35233070 PMCID: PMC8888588 DOI: 10.1038/s42003-022-03124-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 02/01/2022] [Indexed: 11/09/2022] Open
Abstract
Ryanodine receptor 2 (RyR2) is abundantly expressed in the heart and brain. Mutations in RyR2 are associated with both cardiac arrhythmias and intellectual disability. While the mechanisms of RyR2-linked arrhythmias are well characterized, little is known about the mechanism underlying RyR2-associated intellectual disability. Here, we employed a mouse model expressing a green fluorescent protein (GFP)-tagged RyR2 and a specific GFP probe to determine the subcellular localization of RyR2 in hippocampus. GFP-RyR2 was predominantly detected in the soma and dendrites, but not the dendritic spines of CA1 pyramidal neurons or dentate gyrus granular neurons. GFP-RyR2 was also detected within the mossy fibers in the stratum lucidum of CA3, but not in the presynaptic terminals of CA1 neurons. An arrhythmogenic RyR2-R4496C+/− mutation downregulated the A-type K+ current and increased membrane excitability, but had little effect on the afterhyperpolarization current or presynaptic facilitation of CA1 neurons. The RyR2-R4496C+/− mutation also impaired hippocampal long-term potentiation, learning, and memory. These data reveal the precise subcellular distribution of hippocampal RyR2 and its important role in neuronal excitability, learning, and memory. A mouse model containing a GFP-tagged ryanodine receptor 2 (RyR2) has shed light on the precise subcellular localization of hippocampal RyR2 and mechanisms underlying neuronal excitability, learning, and memory.
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Affiliation(s)
- Florian Hiess
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Jinjing Yao
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Zhenpeng Song
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Bo Sun
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Zizhen Zhang
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Junting Huang
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Lina Chen
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Adam Institoris
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - John Paul Estillore
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Ruiwu Wang
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Henk E D J Ter Keurs
- Libin Cardiovascular Institute, Department of Cardiovascular Science, Department of Medicine, University of Calgary, Calgary, AB, Canada
| | - Peter K Stys
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada.,Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada
| | - Grant R Gordon
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Gerald W Zamponi
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Anutosh Ganguly
- Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Calgary, AB, Canada
| | - S R Wayne Chen
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, T2N 4N1, Canada. .,Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada.
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4
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Vallejos MJ, Eadaim A, Hahm ET, Tsunoda S. Age-related changes in Kv4/Shal and Kv1/Shaker expression in Drosophila and a role for reactive oxygen species. PLoS One 2021; 16:e0261087. [PMID: 34932577 PMCID: PMC8691634 DOI: 10.1371/journal.pone.0261087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 11/23/2021] [Indexed: 11/19/2022] Open
Abstract
Age-related changes in ion channel expression are likely to affect neuronal signaling. Here, we examine how age affects Kv4/Shal and Kv1/Shaker K+ channel protein levels in Drosophila. We show that Kv4/Shal protein levels decline sharply from 3 days to 10 days, then more gradually from 10 to 40 days after eclosion. In contrast, Kv1/Shaker protein exhibits a transient increase at 10 days that then stabilizes and eventually declines at 40 days. We present data that begin to show a relationship between reactive oxygen species (ROS), Kv4/Shal, and locomotor performance. We show that Kv4/Shal levels are negatively affected by ROS, and that over-expression of Catalase or RNAi knock-down of the ROS-generating enzyme, Nicotinamide Adenine Dinucleotide Phosphate (NADPH) Oxidase (NOX), can attenuate the loss of Kv4/Shal protein. Finally, we compare levels of Kv4.2 and Kv4.3 in the hippocampus, olfactory bulb, cerebellum, and motor cortex of mice aged 6 weeks and 1 year. While there was no global decline in Kv4.2/4.3 that parallels what we report in Drosophila, we did find that Kv4.2/4.3 are differentially affected in various brain regions; this survey of changes may help inform mammalian studies that examine neuronal function with age.
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Affiliation(s)
- Maximiliano J. Vallejos
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Abdunaser Eadaim
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Eu-Teum Hahm
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Susan Tsunoda
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail:
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5
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Eadaim A, Hahm ET, Justice ED, Tsunoda S. Cholinergic Synaptic Homeostasis Is Tuned by an NFAT-Mediated α7 nAChR-K v4/Shal Coupled Regulatory System. Cell Rep 2021; 32:108119. [PMID: 32905767 PMCID: PMC7521586 DOI: 10.1016/j.celrep.2020.108119] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 06/23/2020] [Accepted: 08/17/2020] [Indexed: 11/26/2022] Open
Abstract
Homeostatic synaptic plasticity (HSP) involves compensatory mechanisms employed by neurons and circuits to preserve signaling when confronted with global changes in activity that may occur during physiological and pathological conditions. Cholinergic neurons, which are especially affected in some pathologies, have recently been shown to exhibit HSP mediated by nicotinic acetylcholine receptors (nAChRs). In Drosophila central neurons, pharmacological blockade of activity induces a homeostatic response mediated by the Drosophila α7 (Dα7) nAChR, which is tuned by a subsequent increase in expression of the voltage-dependent Kv4/Shal channel. Here, we show that an in vivo reduction of cholinergic signaling induces HSP mediated by Dα7 nAChRs, and this upregulation of Dα7 itself is sufficient to trigger transcriptional activation, mediated by nuclear factor of activated T cells (NFAT), of the Kv4/Shal gene, revealing a receptor-ion channel system coupled for homeostatic tuning in cholinergic neurons. Eadaim et al. show that in vivo reduction of cholinergic signaling in Drosophila neurons induces synaptic homeostasis mediated by Dα7 nAChRs. This upregulation of Dα7 induces Kv4/Shal gene expression mediated by nuclear factor of activated T cells (NFAT), revealing a receptor-ion channel system coupled for homeostatic tuning in cholinergic neurons.
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Affiliation(s)
- Abdunaser Eadaim
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Eu-Teum Hahm
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Elizabeth D Justice
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Susan Tsunoda
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
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6
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Yao J, Sun B, Institoris A, Zhan X, Guo W, Song Z, Liu Y, Hiess F, Boyce AKJ, Ni M, Wang R, Ter Keurs H, Back TG, Fill M, Thompson RJ, Turner RW, Gordon GR, Chen SRW. Limiting RyR2 Open Time Prevents Alzheimer's Disease-Related Neuronal Hyperactivity and Memory Loss but Not β-Amyloid Accumulation. Cell Rep 2021; 32:108169. [PMID: 32966798 PMCID: PMC7532726 DOI: 10.1016/j.celrep.2020.108169] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 07/23/2020] [Accepted: 08/27/2020] [Indexed: 12/31/2022] Open
Abstract
Neuronal hyperactivity is an early primary dysfunction in Alzheimer’s disease (AD) in humans and animal models, but effective neuronal hyperactivity-directed anti-AD therapeutic agents are lacking. Here we define a previously unknown mode of ryanodine receptor 2 (RyR2) control of neuronal hyperactivity and AD progression. We show that a single RyR2 point mutation, E4872Q, which reduces RyR2 open time, prevents hyperexcitability, hyperactivity, memory impairment, neuronal cell death, and dendritic spine loss in a severe early-onset AD mouse model (5xFAD). The RyR2-E4872Q mutation upregulates hippocampal CA1-pyramidal cell A-type K+ current, a well-known neuronal excitability control that is downregulated in AD. Pharmacologically limiting RyR2 open time with the R-carvedilol enantiomer (but not racemic carvedilol) prevents and rescues neuronal hyperactivity, memory impairment, and neuron loss even in late stages of AD. These AD-related deficits are prevented even with continued β-amyloid accumulation. Thus, limiting RyR2 open time may be a hyperactivity-directed, non-β-amyloid-targeted anti-AD strategy. Yao et al. show that genetically or pharmacologically limiting the open duration of ryanodine receptor 2 upregulates the A-type potassium current and prevents neuronal hyperexcitability and hyperactivity, memory impairment, neuronal cell death, and dendritic spine loss in a severe early-onset Alzheimer’s disease mouse model, even with continued accumulation of β-amyloid.
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Affiliation(s)
- Jinjing Yao
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Bo Sun
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; Medical School, Kunming University of Science and Technology, Kunming 650504, China
| | - Adam Institoris
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Xiaoqin Zhan
- Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Wenting Guo
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Zhenpeng Song
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Yajing Liu
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Florian Hiess
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Andrew K J Boyce
- Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Mingke Ni
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Ruiwu Wang
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Henk Ter Keurs
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Thomas G Back
- Department of Chemistry, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Michael Fill
- Department of Physiology & Biophysics, Rush University Medical Center, Chicago, IL 60612, USA
| | - Roger J Thompson
- Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Ray W Turner
- Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Grant R Gordon
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - S R Wayne Chen
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; Department of Physiology & Biophysics, Rush University Medical Center, Chicago, IL 60612, USA.
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7
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Hu JH, Malloy C, Hoffman DA. P38 Regulates Kainic Acid-Induced Seizure and Neuronal Firing via Kv4.2 Phosphorylation. Int J Mol Sci 2020; 21:ijms21165921. [PMID: 32824677 PMCID: PMC7460594 DOI: 10.3390/ijms21165921] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/06/2020] [Accepted: 08/14/2020] [Indexed: 01/23/2023] Open
Abstract
The subthreshold, transient A-type K+ current is a vital regulator of the excitability of neurons throughout the brain. In mammalian hippocampal pyramidal neurons, this current is carried primarily by ion channels comprising Kv4.2 α-subunits. These channels occupy the somatodendritic domains of these principle excitatory neurons and thus regulate membrane voltage relevant to the input-output efficacy of these cells. Owing to their robust control of membrane excitability and ubiquitous expression in the hippocampus, their dysfunction can alter network stability in a manner that manifests in recurrent seizures. Indeed, growing evidence implicates these channels in intractable epilepsies of the temporal lobe, which underscores the importance of determining the molecular mechanisms underlying their regulation and contribution to pathologies. Here, we describe the role of p38 kinase phosphorylation of a C-terminal motif in Kv4.2 in modulating hippocampal neuronal excitability and behavioral seizure strength. Using a combination of biochemical, single-cell electrophysiology, and in vivo seizure techniques, we show that kainic acid-induced seizure induces p38-mediated phosphorylation of Thr607 in Kv4.2 in a time-dependent manner. The pharmacological and genetic disruption of this process reduces neuronal excitability and dampens seizure intensity, illuminating a cellular cascade that may be targeted for therapeutic intervention to mitigate seizure intensity and progression.
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8
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Chittajallu R, Auville K, Mahadevan V, Lai M, Hunt S, Calvigioni D, Pelkey KA, Zaghloul KA, McBain CJ. Activity-dependent tuning of intrinsic excitability in mouse and human neurogliaform cells. eLife 2020; 9:57571. [PMID: 32496194 PMCID: PMC7299336 DOI: 10.7554/elife.57571] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 06/02/2020] [Indexed: 12/15/2022] Open
Abstract
The ability to modulate the efficacy of synaptic communication between neurons constitutes an essential property critical for normal brain function. Animal models have proved invaluable in revealing a wealth of diverse cellular mechanisms underlying varied plasticity modes. However, to what extent these processes are mirrored in humans is largely uncharted thus questioning their relevance in human circuit function. In this study, we focus on neurogliaform cells, that possess specialized physiological features enabling them to impart a widespread inhibitory influence on neural activity. We demonstrate that this prominent neuronal subtype, embedded in both mouse and human neural circuits, undergo remarkably similar activity-dependent modulation manifesting as epochs of enhanced intrinsic excitability. In principle, these evolutionary conserved plasticity routes likely tune the extent of neurogliaform cell mediated inhibition thus constituting canonical circuit mechanisms underlying human cognitive processing and behavior.
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Affiliation(s)
- Ramesh Chittajallu
- Laboratory of Cellular and Synaptic Physiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Kurt Auville
- Laboratory of Cellular and Synaptic Physiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Vivek Mahadevan
- Laboratory of Cellular and Synaptic Physiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Mandy Lai
- Laboratory of Cellular and Synaptic Physiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Steven Hunt
- Laboratory of Cellular and Synaptic Physiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Daniela Calvigioni
- Laboratory of Cellular and Synaptic Physiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Kenneth A Pelkey
- Laboratory of Cellular and Synaptic Physiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Kareem A Zaghloul
- Surgical Neurology Branch, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Chris J McBain
- Laboratory of Cellular and Synaptic Physiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
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Yang X, Bao Y, Xu J, Gong R, Zhang N, Cai L, Xia M, Wang J, Lu W. Long-Lasting Somatic Modifications of Convergent Dendritic Inputs in Hippocampal Neurons. Cereb Cortex 2020; 30:1436-1446. [PMID: 31504279 DOI: 10.1093/cercor/bhz177] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Integrated neural inputs from different dendrites converge at the soma for action potential generation. However, it is unclear how the convergent dendritic inputs interact at the soma and whether they can be further modified there. We report here an entirely new plasticity rule in hippocampal neurons in which repetitive pairing of subthreshold excitatory inputs from proximal apical and basal dendrites at a precise interval induces persistent bidirectional modifications of the two dendritic inputs. Strikingly, the modification of the dendritic inputs specially occurs at soma in the absence of somatic action potential and requires activation of somatic N-methyl-D-aspartate receptors (NMDARs). Once induced, the somatic modification can also be observed in other unpaired dendritic inputs upon their arrival at the soma. We further reveal that the soma can employ an active mechanism to potentiate the dendritic inputs by promoting sustained activation of somatic NMDARs and subsequent down-regulating of the fast inactivating A-type potassium current (IA) at the soma. Thus, the input-timing-dependent somatic plasticity we uncovered here is in sharp contrast to conventional forms of synaptic plasticity that occur at the dendrites and is important to somatic action potential generation.
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Affiliation(s)
- Xin Yang
- State Key Laboratory of Bioelectronics, Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu Province 210096, China
| | - Yifei Bao
- State Key Laboratory of Bioelectronics, Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu Province 210096, China
| | - Jindong Xu
- Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province 226001, People's Republic of China
| | - Ru Gong
- State Key Laboratory of Bioelectronics, Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu Province 210096, China
| | - Nan Zhang
- Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province 226001, People's Republic of China
| | - Lei Cai
- Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province 226001, People's Republic of China
| | - Mingmei Xia
- State Key Laboratory of Bioelectronics, Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu Province 210096, China
| | - Jingjing Wang
- Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province 226001, People's Republic of China.,Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200011, China
| | - Wei Lu
- State Key Laboratory of Bioelectronics, Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu Province 210096, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province 226001, People's Republic of China.,Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029, China
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10
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Siddiqui S, Khan F, Jamali KS, Musharraf SG. Madecassic Acid Reduces Fast Transient Potassium Channels and Promotes Neurite Elongation in Hippocampal CA1 Neurons. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2019; 19:12-26. [PMID: 31713492 DOI: 10.2174/1871527318666191111105508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 10/21/2019] [Accepted: 10/22/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND OBJECTIVE Madecassic Acid (MA) is well known to induce neurite elongation. However, its correlation with the expression of fast transient potassium (AKv) channels during neuronal development has not been well studied. Therefore, the present study was designed to investigate the effects of MA on the modulation of AKv channels during neurite outgrowth. METHODS Neurite outgrowth was measured with morphometry software, and Kv4 currents were recorded by using the patch clamp technique. RESULTS The ability of MA to promote neurite outgrowth is dose-dependent and was blocked by using the mitogen/extracellular signal-regulated kinase (MEK) inhibitor U0126. MA reduced the peak current density and surface expression of the AKv channel Kv4.2 with or without the presence of NaN3. The surface expression of Kv4.2 channels was also reduced after MA treatment of growing neurons. Ethylene glycol tetraacetic acid (EGTA) and an N-methyl-D-aspartate (NMDA) receptor blocker, MK801 along with MA prevented the effect of MA on neurite length, indicating that calcium entry through NMDA receptors is necessary for MA-induced neurite outgrowth. CONCLUSION The data demonstrated that MA increased neurite outgrowth by internalizing AKv channels in neurons. Any alterations in the precise density of ion channels can lead to deleterious consequences on health because it changes the electrical and mechanical function of a neuron or a cell. Modulating ion channel's density is exciting research in order to develop novel drugs for the therapeutic treatment of various diseases of CNS.
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Affiliation(s)
- Sonia Siddiqui
- Department of Biochemistry, Dow University of Health Sciences (DUHS), Karachi, Pakistan.,Department of Neuroscience, Dr. Panjwani Center for Molecular Medicine and Drug Research (PCMD), International Center for Chemical and Biological Sciences (ICCBS), University of Karachi 75270, Pakistan
| | - Faisal Khan
- Department of Neuroscience, Dr. Panjwani Center for Molecular Medicine and Drug Research (PCMD), International Center for Chemical and Biological Sciences (ICCBS), University of Karachi 75270, Pakistan
| | - Khawar Saeed Jamali
- Department of Surgery, Dow University of Health Sciences (DUHS), Karachi, Pakistan
| | - Syed Ghulam Musharraf
- HEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi 75270, Pakistan
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11
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Reuveni I, Barkai E. Tune it in: mechanisms and computational significance of neuron-autonomous plasticity. J Neurophysiol 2018; 120:1781-1795. [DOI: 10.1152/jn.00102.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The activity of a neural network is a result of synaptic signals that convey the communication between neurons and neuron-based intrinsic currents that determine the neuron’s input-output transfer function. Ample studies have demonstrated that cell-based excitability, and in particular intrinsic excitability, is modulated by learning and that these modifications play a key role in learning-related behavioral changes. The field of cell-based plasticity is largely growing, and it entails numerous experimental findings that demonstrate a large diversity of currents that are affected by learning. The diverse effect of learning on the neuron’s excitability emphasizes the need for a framework under which cell-based plasticity can be categorized to enable the assessment of the computational roles of the intrinsic modifications. We divide the domain of cell-based plasticity into three main categories, where the first category entails the currents that mediate the passive properties and single-spike generation, the second category entails the currents that mediate spike frequency adaptation, and the third category entails a novel learning-induced mechanism where all excitatory and inhibitory synapses double their strength. Curiously, this elementary division enables a natural categorization of the computational roles of these learning-induced plasticities. The computational roles are diverse and include modification of the neuronal mode of action, such as bursting, prolonged, and fast responsive; attention-like effect where the signal detection is improved; transfer of the network into an active state; biasing the competition for memory allocation; and transforming an environmental cue into a dominant cue and enabling a quicker formation of new memories.
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Affiliation(s)
- Iris Reuveni
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Edi Barkai
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
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12
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Shim HG, Lee YS, Kim SJ. The Emerging Concept of Intrinsic Plasticity: Activity-dependent Modulation of Intrinsic Excitability in Cerebellar Purkinje Cells and Motor Learning. Exp Neurobiol 2018; 27:139-154. [PMID: 30022866 PMCID: PMC6050419 DOI: 10.5607/en.2018.27.3.139] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 06/28/2018] [Accepted: 06/28/2018] [Indexed: 12/15/2022] Open
Abstract
What is memory? How does the brain process the sensory information and modify an organism's behavior? Many neuroscientists have focused on the activity- and experience-dependent modifications of synaptic functions in order to solve these fundamental questions in neuroscience. Recently, the plasticity of intrinsic excitability (called intrinsic plasticity) has emerged as an important element for information processing and storage in the brain. As the cerebellar Purkinje cells are the sole output neurons in the cerebellar cortex and the information is conveyed from a neuron to its relay neurons by forms of action potential firing, the modulation of the intrinsic firing activity may play a critical role in the cerebellar learning. Many voltage-gated and/or Ca2+-activated ion channels are involved in shaping the spiking output as well as integrating synaptic inputs to finely tune the cerebellar output. Recent studies suggested that the modulation of the intrinsic excitability and its plasticity in the cerebellar Purkinje cells might function as an integrator for information processing and memory formation. Moreover, the intrinsic plasticity might also determine the strength of connectivity to the sub-cortical areas such as deep cerebellar nuclei and vestibular nuclei to trigger the consolidation of the cerebellar-dependent memory by transferring the information.
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Affiliation(s)
- Hyun Geun Shim
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea
- Department of Biomedical Science, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Yong-Seok Lee
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea
- Department of Biomedical Science, Seoul National University College of Medicine, Seoul 03080, Korea
- Neuroscience Research Institute, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Sang Jeong Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea
- Department of Biomedical Science, Seoul National University College of Medicine, Seoul 03080, Korea
- Neuroscience Research Institute, Seoul National University College of Medicine, Seoul 03080, Korea
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13
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Wild AR, Dell'Acqua ML. Potential for therapeutic targeting of AKAP signaling complexes in nervous system disorders. Pharmacol Ther 2017; 185:99-121. [PMID: 29262295 DOI: 10.1016/j.pharmthera.2017.12.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A common feature of neurological and neuropsychiatric disorders is a breakdown in the integrity of intracellular signal transduction pathways. Dysregulation of ion channels and receptors in the cell membrane and the enzymatic mediators that link them to intracellular effectors can lead to synaptic dysfunction and neuronal death. However, therapeutic targeting of these ubiquitous signaling elements can lead to off-target side effects due to their widespread expression in multiple systems of the body. A-kinase anchoring proteins (AKAPs) are multivalent scaffolding proteins that compartmentalize a diverse range of receptor and effector proteins to streamline signaling within nanodomain signalosomes. A number of essential neurological processes are known to critically depend on AKAP-directed signaling and an understanding of the role AKAPs play in nervous system disorders has emerged in recent years. Selective targeting of AKAP protein-protein interactions may be a means to uncouple pathologically active signaling pathways in neurological disorders with a greater degree of specificity. In this review we will discuss the role of AKAPs in both regulating normal nervous system function and dysfunction associated with disease, and the potential for therapeutic targeting of AKAP signaling complexes.
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Affiliation(s)
- Angela R Wild
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Mark L Dell'Acqua
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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14
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McKiernan EC, Marrone DF. CA1 pyramidal cells have diverse biophysical properties, affected by development, experience, and aging. PeerJ 2017; 5:e3836. [PMID: 28948109 PMCID: PMC5609525 DOI: 10.7717/peerj.3836] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 08/31/2017] [Indexed: 12/04/2022] Open
Abstract
Neuron types (e.g., pyramidal cells) within one area of the brain are often considered homogeneous, despite variability in their biophysical properties. Here we review literature demonstrating variability in the electrical activity of CA1 hippocampal pyramidal cells (PCs), including responses to somatic current injection, synaptic stimulation, and spontaneous network-related activity. In addition, we describe how responses of CA1 PCs vary with development, experience, and aging, and some of the underlying ionic currents responsible. Finally, we suggest directions that may be the most impactful in expanding this knowledge, including the use of text and data mining to systematically study cellular heterogeneity in more depth; dynamical systems theory to understand and potentially classify neuron firing patterns; and mathematical modeling to study the interaction between cellular properties and network output. Our goals are to provide a synthesis of the literature for experimentalists studying CA1 PCs, to give theorists an idea of the rich diversity of behaviors models may need to reproduce to accurately represent these cells, and to provide suggestions for future research.
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Affiliation(s)
- Erin C McKiernan
- Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Diano F Marrone
- Department of Psychology, Wilfrid Laurier University, Waterloo, Ontario, Canada.,McKnight Brain Institute, University of Arizona, Tucson, AZ, United States of America
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15
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Alcohol Regulates BK Surface Expression via Wnt/β-Catenin Signaling. J Neurosci 2017; 36:10625-10639. [PMID: 27733613 DOI: 10.1523/jneurosci.0491-16.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 07/27/2016] [Indexed: 12/26/2022] Open
Abstract
It has been suggested that drug tolerance represents a form of learning and memory, but this has not been experimentally established at the molecular level. We show that a component of alcohol molecular tolerance (channel internalization) from rat hippocampal neurons requires protein synthesis, in common with other forms of learning and memory. We identify β-catenin as a primary necessary protein. Alcohol increases β-catenin, and blocking accumulation of β-catenin blocks alcohol-induced internalization in these neurons. In transfected HEK293 cells, suppression of Wnt/β-catenin signaling blocks ethanol-induced internalization. Conversely, activation of Wnt/β-catenin reduces BK current density. A point mutation in a putative glycogen synthase kinase phosophorylation site within the S10 region of BK blocks internalization, suggesting that Wnt/β-catenin directly regulates alcohol-induced BK internalization via glycogen synthase kinase phosphorylation. These findings establish de novo protein synthesis and Wnt/β-catenin signaling as critical in mediating a persistent form of BK molecular alcohol tolerance establishing a commonality with other forms of long-term plasticity. SIGNIFICANCE STATEMENT Alcohol tolerance is a key step toward escalating alcohol consumption and subsequent dependence. Our research aims to make significant contributions toward novel, therapeutic approaches to prevent and treat alcohol misuse by understanding the molecular mechanisms of alcohol tolerance. In our current study, we identify the role of a key regulatory pathway in alcohol-induced persistent molecular changes within the hippocampus. The canonical Wnt/β-catenin pathway regulates BK channel surface expression in a protein synthesis-dependent manner reminiscent of other forms of long-term hippocampal neuronal adaptations. This unique insight opens the possibility of using clinically tested drugs, targeting the Wnt/β-catenin pathway, for the novel use of preventing and treating alcohol dependency.
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16
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Yang YS, Jeon SC, Kang MS, Kim SH, Eun SY, Jin SH, Jung SC. Activation of ryanodine receptors is required for PKA-mediated downregulation of A-type K+channels in rat hippocampal neurons. J Neurosci Res 2017; 95:2469-2482. [DOI: 10.1002/jnr.24076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 04/07/2017] [Accepted: 04/10/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Yoon-Sil Yang
- Department of Physiology, School of Medicine
- Department of Structure and Function of Neural Network; Korea Brain Research Institute; 41068, Daegu Republic of Korea
| | | | | | | | - Su-Yong Eun
- Department of Physiology, School of Medicine
| | - Soo-Hee Jin
- Department of Preventive Medicine; School of Medicine, Kyungpook National University; 41566
| | - Sung-Cherl Jung
- Department of Physiology, School of Medicine
- Institute of Medical Science, Jeju National University, 63243; Jeju
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17
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Role of low-voltage-activated calcium current and extracellular calcium in controlling the firing pattern of developing CA1 pyramidal neurons. Neuroscience 2017; 344:89-101. [DOI: 10.1016/j.neuroscience.2016.12.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Revised: 12/07/2016] [Accepted: 12/16/2016] [Indexed: 11/19/2022]
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18
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Knight JC, Tully PJ, Kaplan BA, Lansner A, Furber SB. Large-Scale Simulations of Plastic Neural Networks on Neuromorphic Hardware. Front Neuroanat 2016; 10:37. [PMID: 27092061 PMCID: PMC4823276 DOI: 10.3389/fnana.2016.00037] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/18/2016] [Indexed: 11/17/2022] Open
Abstract
SpiNNaker is a digital, neuromorphic architecture designed for simulating large-scale spiking neural networks at speeds close to biological real-time. Rather than using bespoke analog or digital hardware, the basic computational unit of a SpiNNaker system is a general-purpose ARM processor, allowing it to be programmed to simulate a wide variety of neuron and synapse models. This flexibility is particularly valuable in the study of biological plasticity phenomena. A recently proposed learning rule based on the Bayesian Confidence Propagation Neural Network (BCPNN) paradigm offers a generic framework for modeling the interaction of different plasticity mechanisms using spiking neurons. However, it can be computationally expensive to simulate large networks with BCPNN learning since it requires multiple state variables for each synapse, each of which needs to be updated every simulation time-step. We discuss the trade-offs in efficiency and accuracy involved in developing an event-based BCPNN implementation for SpiNNaker based on an analytical solution to the BCPNN equations, and detail the steps taken to fit this within the limited computational and memory resources of the SpiNNaker architecture. We demonstrate this learning rule by learning temporal sequences of neural activity within a recurrent attractor network which we simulate at scales of up to 2.0 × 104 neurons and 5.1 × 107 plastic synapses: the largest plastic neural network ever to be simulated on neuromorphic hardware. We also run a comparable simulation on a Cray XC-30 supercomputer system and find that, if it is to match the run-time of our SpiNNaker simulation, the super computer system uses approximately 45× more power. This suggests that cheaper, more power efficient neuromorphic systems are becoming useful discovery tools in the study of plasticity in large-scale brain models.
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Affiliation(s)
- James C Knight
- Advanced Processor Technologies Group, School of Computer Science, University of Manchester Manchester, UK
| | - Philip J Tully
- Department of Computational Biology, Royal Institute of TechnologyStockholm, Sweden; Stockholm Brain Institute, Karolinska InstituteStockholm, Sweden; Institute for Adaptive and Neural Computation, School of Informatics, University of EdinburghEdinburgh, UK
| | - Bernhard A Kaplan
- Department of Visualization and Data Analysis, Zuse Institute Berlin Berlin, Germany
| | - Anders Lansner
- Department of Computational Biology, Royal Institute of TechnologyStockholm, Sweden; Stockholm Brain Institute, Karolinska InstituteStockholm, Sweden; Department of Numerical analysis and Computer Science, Stockholm UniversityStockholm, Sweden
| | - Steve B Furber
- Advanced Processor Technologies Group, School of Computer Science, University of Manchester Manchester, UK
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19
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Szücs A, Huerta R. Differential effects of static and dynamic inputs on neuronal excitability. J Neurophysiol 2015; 113:232-43. [PMID: 25274346 DOI: 10.1152/jn.00226.2014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The intrinsic excitability of neurons is known to be dynamically regulated by activity-dependent plasticity and homeostatic mechanisms. Such processes are commonly analyzed in the context of input-output functions that describe how neurons fire in response to constant levels of current. However, it is not well understood how changes of excitability as observed under static inputs translate to the function of the same neurons in their natural synaptic environment. Here we performed a computational study and hybrid experiments on rat bed nucleus of stria terminalis neurons to compare the two scenarios. The inward rectifying Kir current (IKir) and the hyperpolarization-activated cation current (Ih) were found to be considerably more effective in regulating the firing under synaptic inputs than under static stimuli. This prediction was experimentally confirmed by dynamic-clamp insertion of a synthetic inwardly rectifying Kir current into the biological neurons. At the same time, ionic currents that activate with depolarization were more effective regulating the firing under static inputs. When two intrinsic currents are concurrently altered such as those under homeostatic regulation, the effects in firing responses under static vs. dynamic inputs can be even more contrasting. Our results show that plastic or homeostatic changes of intrinsic membrane currents can shape the current step responses of neurons and their firing under synaptic inputs in a differential manner.
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Affiliation(s)
- Attila Szücs
- BioCircuits Institute, University of California, San Diego, La Jolla, California; and Balaton Limnological Institute, Center of Ecology of the Hungarian Academy of Sciences, Tihany, Hungary
| | - Ramon Huerta
- BioCircuits Institute, University of California, San Diego, La Jolla, California; and
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20
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Tully PJ, Hennig MH, Lansner A. Synaptic and nonsynaptic plasticity approximating probabilistic inference. Front Synaptic Neurosci 2014; 6:8. [PMID: 24782758 PMCID: PMC3986567 DOI: 10.3389/fnsyn.2014.00008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 03/20/2014] [Indexed: 12/28/2022] Open
Abstract
Learning and memory operations in neural circuits are believed to involve molecular cascades of synaptic and nonsynaptic changes that lead to a diverse repertoire of dynamical phenomena at higher levels of processing. Hebbian and homeostatic plasticity, neuromodulation, and intrinsic excitability all conspire to form and maintain memories. But it is still unclear how these seemingly redundant mechanisms could jointly orchestrate learning in a more unified system. To this end, a Hebbian learning rule for spiking neurons inspired by Bayesian statistics is proposed. In this model, synaptic weights and intrinsic currents are adapted on-line upon arrival of single spikes, which initiate a cascade of temporally interacting memory traces that locally estimate probabilities associated with relative neuronal activation levels. Trace dynamics enable synaptic learning to readily demonstrate a spike-timing dependence, stably return to a set-point over long time scales, and remain competitive despite this stability. Beyond unsupervised learning, linking the traces with an external plasticity-modulating signal enables spike-based reinforcement learning. At the postsynaptic neuron, the traces are represented by an activity-dependent ion channel that is shown to regulate the input received by a postsynaptic cell and generate intrinsic graded persistent firing levels. We show how spike-based Hebbian-Bayesian learning can be performed in a simulated inference task using integrate-and-fire (IAF) neurons that are Poisson-firing and background-driven, similar to the preferred regime of cortical neurons. Our results support the view that neurons can represent information in the form of probability distributions, and that probabilistic inference could be a functional by-product of coupled synaptic and nonsynaptic mechanisms operating over several timescales. The model provides a biophysical realization of Bayesian computation by reconciling several observed neural phenomena whose functional effects are only partially understood in concert.
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Affiliation(s)
- Philip J Tully
- Department of Computational Biology, Royal Institute of Technology (KTH) Stockholm, Sweden ; Stockholm Brain Institute, Karolinska Institute Stockholm, Sweden ; School of Informatics, Institute for Adaptive and Neural Computation, University of Edinburgh Edinburgh, UK
| | - Matthias H Hennig
- School of Informatics, Institute for Adaptive and Neural Computation, University of Edinburgh Edinburgh, UK
| | - Anders Lansner
- Department of Computational Biology, Royal Institute of Technology (KTH) Stockholm, Sweden ; Stockholm Brain Institute, Karolinska Institute Stockholm, Sweden ; Department of Numerical Analysis and Computer Science, Stockholm University Stockholm, Sweden
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21
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Kang MS, Yang YS, Kim SH, Park JM, Eun SY, Jung SC. The Downregulation of Somatic A-Type K(+) Channels Requires the Activation of Synaptic NMDA Receptors in Young Hippocampal Neurons of Rats. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2014; 18:135-41. [PMID: 24757375 PMCID: PMC3994300 DOI: 10.4196/kjpp.2014.18.2.135] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 02/24/2014] [Accepted: 02/26/2014] [Indexed: 11/24/2022]
Abstract
The downregulation of A-type K+ channels (IA channels) accompanying enhanced somatic excitability can mediate epileptogenic conditions in mammalian central nervous system. As IA channels are dominantly targeted by dendritic and postsynaptic processings during synaptic plasticity, it is presumable that they may act as cellular linkers between synaptic responses and somatic processings under various excitable conditions. In the present study, we electrophysiologically tested if the downregulation of somatic IA channels was sensitive to synaptic activities in young hippocampal neurons. In primarily cultured hippocampal neurons (DIV 6~9), the peak of IA recorded by a whole-cell patch was significantly reduced by high KCl or exogenous glutamate treatment to enhance synaptic activities. However, the pretreatment of MK801 to block synaptic NMDA receptors abolished the glutamate-induced reduction of the IA peak, indicating the necessity of synaptic activation for the reduction of somatic IA. This was again confirmed by glycine treatment, showing a significant reduction of the somatic IA peak. Additionally, the gating property of IA channels was also sensitive to the activation of synaptic NMDA receptors, showing the hyperpolarizing shift in inactivation kinetics. These results suggest that synaptic LTP possibly potentiates somatic excitability via downregulating IA channels in expression and gating kinetics. The consequential changes of somatic excitability following the activity-dependent modulation of synaptic responses may be a series of processings for neuronal functions to determine outputs in memory mechanisms or pathogenic conditions.
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Affiliation(s)
- Moon-Seok Kang
- Department of Physiology, School of Medicine, Jeju National University, Jeju 690-756, Korea
| | - Yoon-Sil Yang
- Department of Physiology, School of Medicine, Jeju National University, Jeju 690-756, Korea
| | - Seon-Hee Kim
- Department of Physiology, School of Medicine, Jeju National University, Jeju 690-756, Korea
| | - Joo-Min Park
- Department of Physiology, School of Medicine, Jeju National University, Jeju 690-756, Korea
| | - Su-Yong Eun
- Department of Physiology, School of Medicine, Jeju National University, Jeju 690-756, Korea
| | - Sung-Cherl Jung
- Department of Physiology, School of Medicine, Jeju National University, Jeju 690-756, Korea. ; Institute of Medical Science, Jeju National University, Jeju 690-756, Korea
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22
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Distinct and simultaneously active plasticity mechanisms in mouse hippocampus during different phases of Morris water maze training. Brain Struct Funct 2014; 220:1273-90. [PMID: 24562414 DOI: 10.1007/s00429-014-0722-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Accepted: 01/28/2014] [Indexed: 01/30/2023]
Abstract
Although the Morris water maze (MWM) is the most frequently used protocol to examine hippocampus-dependent learning in mice, not much is known about the spatio-temporal dynamics of underlying plasticity processes. Here, we studied molecular and cellular hippocampal plasticity mechanisms during early and late phases of spatial learning in the MWM. Quantitative in situ hybridization for the immediate early genes zif268 and Homer1a (H1a) revealed phase-dependent differences in their expression between areas CA1 and CA3. During the initial learning phase, CA1 expression levels of the molecular plasticity marker H1a, but not of the activity reporter gene zif268, were related to task proficiency; whereas no learning-specific changes could be detected in CA3. Simultaneously, the ratio of surface-expressed NMDAR subunits NR2A and NR2B was downregulated as measured by acute slice biotinylation assay, while the total number of surface NMDARs was unaltered. When intrinsic 'somatic' and synaptic plasticity in the CA1-region of hippocampal slices were examined, we found that early learning promotes intrinsic neuronal plasticity as manifested by a reduction of spike frequency adaptation and postburst afterhyperpolarization. At the synaptic level, however, maintenance of long-term potentiation (LTP) in all learning groups was impaired which is most likely due to 'intrinsic' learning-induced LTP which occluded any further electrically induced LTP. Late learning, in contrast, was characterized by re-normalized H1a, NR2A and NR2B expression and neuronal firing, yet a further strengthening of learning-induced LTP. Together, our data support a precisely timed cascade of complex molecular and subcellular transformations occurring from early to late MWM learning.
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23
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Yang YS, Kim KD, Eun SY, Jung SC. Roles of somatic A-type K(+) channels in the synaptic plasticity of hippocampal neurons. Neurosci Bull 2014; 30:505-14. [PMID: 24526657 DOI: 10.1007/s12264-013-1399-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 07/19/2013] [Indexed: 01/11/2023] Open
Abstract
In the mammalian brain, information encoding and storage have been explained by revealing the cellular and molecular mechanisms of synaptic plasticity at various levels in the central nervous system, including the hippocampus and the cerebral cortices. The modulatory mechanisms of synaptic excitability that are correlated with neuronal tasks are fundamental factors for synaptic plasticity, and they are dependent on intracellular Ca(2+)-mediated signaling. In the present review, the A-type K(+) (IA) channel, one of the voltage-dependent cation channels, is considered as a key player in the modulation of Ca(2+) influx through synaptic NMDA receptors and their correlated signaling pathways. The cellular functions of IA channels indicate that they possibly play as integral parts of synaptic and somatic complexes, completing the initiation and stabilization of memory.
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Affiliation(s)
- Yoon-Sil Yang
- Department of Physiology, School of Medicine, Jeju National University, Jeju, 690756, Republic of Korea
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24
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Wójtowicz T, Mozrzymas JW. Matrix metalloprotease activity shapes the magnitude of EPSPs and spike plasticity within the hippocampal CA3 network. Hippocampus 2013; 24:135-53. [DOI: 10.1002/hipo.22205] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/09/2013] [Indexed: 02/06/2023]
Affiliation(s)
- Tomasz Wójtowicz
- Laboratory of Neuroscience, Department of Biophysics; Wroclaw Medical University; Chalubinskiego 3 50368 Wroclaw Poland
| | - Jerzy W. Mozrzymas
- Laboratory of Neuroscience, Department of Biophysics; Wroclaw Medical University; Chalubinskiego 3 50368 Wroclaw Poland
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25
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Lansner A, Marklund P, Sikström S, Nilsson LG. Reactivation in working memory: an attractor network model of free recall. PLoS One 2013; 8:e73776. [PMID: 24023690 PMCID: PMC3758294 DOI: 10.1371/journal.pone.0073776] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 07/23/2013] [Indexed: 11/18/2022] Open
Abstract
The dynamic nature of human working memory, the general-purpose system for processing continuous input, while keeping no longer externally available information active in the background, is well captured in immediate free recall of supraspan word-lists. Free recall tasks produce several benchmark memory phenomena, like the U-shaped serial position curve, reflecting enhanced memory for early and late list items. To account for empirical data, including primacy and recency as well as contiguity effects, we propose here a neurobiologically based neural network model that unifies short- and long-term forms of memory and challenges both the standard view of working memory as persistent activity and dual-store accounts of free recall. Rapidly expressed and volatile synaptic plasticity, modulated intrinsic excitability, and spike-frequency adaptation are suggested as key cellular mechanisms underlying working memory encoding, reactivation and recall. Recent findings on the synaptic and molecular mechanisms behind early LTP and on spiking activity during delayed-match-to-sample tasks support this view.
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Affiliation(s)
- Anders Lansner
- Department of Numerical Analysis and Computer Science, Stockholm University, Stockholm, Sweden
- School of Computer Science and Communication, Department of Computational Biology, KTH (Royal Institute of Technology), Stockholm, Sweden
- Stockholm Brain Institute, Stockholm, Sweden
| | - Petter Marklund
- Stockholm Brain Institute, Stockholm, Sweden
- Department of Psychology, Stockholm University, Stockholm, Sweden
| | - Sverker Sikström
- Stockholm Brain Institute, Stockholm, Sweden
- Department of Psychology, Lund University, Lund, Sweden
| | - Lars-Göran Nilsson
- Stockholm Brain Institute, Stockholm, Sweden
- Department of Psychology, Stockholm University, Stockholm, Sweden
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26
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Gomes GM, Dalmolin GD, Cordeiro MDN, Gomez MV, Ferreira J, Rubin MA. The selective A-type K+ current blocker Tx3-1 isolated from the Phoneutria nigriventer venom enhances memory of naïve and Aβ(25-35)-treated mice. Toxicon 2013; 76:23-7. [PMID: 23994427 DOI: 10.1016/j.toxicon.2013.08.059] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 08/07/2013] [Accepted: 08/13/2013] [Indexed: 11/15/2022]
Abstract
Potassium channels regulate many neuronal functions, including neuronal excitability and synaptic plasticity, contributing, by these means, to mnemonic processes. In particular, A-type K(+) currents (IA) play a key role in hippocampal synaptic plasticity. Therefore, we evaluated the effect of the peptidic toxin Tx3-1, a selective blocker of IA currents, extracted from the venom of the spider Phoneutria nigriventer, on memory of mice. Administration of Tx3-1 (i.c.v., 300 pmol/site) enhanced both short- and long-term memory consolidation of mice tested in the novel object recognition task. In comparison, 4-aminopyridine (4-AP; i.c.v., 30-300 pmol/site), a non-selective K(+) channel blocker did not alter long-term memory and caused toxic side effects such as circling, freezing and tonic-clonic seizures. Moreover, Tx3-1 (i.c.v., 10-100 pmol/site) restored memory of Aβ25-35-injected mice, and exhibited a higher potency to improve memory of Aβ25-35-injected mice when compared to control group. These results show the effect of the selective blocker of IA currents Tx3-1 in both short- and long-term memory retention and in memory impairment caused by Aβ25-35, reinforcing the role of IA in physiological and pathological memory processes.
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Affiliation(s)
- Guilherme M Gomes
- Graduation Program in Biological Sciences, Toxicological Biochemistry, Building 18, Room 2203, Center of Exact and Natural Sciences, Federal University of Santa Maria, Santa Maria, RS 97105-900, Brazil
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Li Q, Fleming RL, Acheson SK, Madison RD, Moore SD, Risher ML, Wilson WA, Swartzwelder HS. Long-term modulation of A-type K(+) conductances in hippocampal CA1 interneurons in rats after chronic intermittent ethanol exposure during adolescence or adulthood. Alcohol Clin Exp Res 2013; 37:2074-85. [PMID: 23889304 DOI: 10.1111/acer.12204] [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] [Received: 03/25/2013] [Accepted: 04/29/2013] [Indexed: 12/14/2022]
Abstract
BACKGROUND Chronic alcohol use, especially exposure to alcohol during adolescence or young adulthood, is closely associated with cognitive deficits that may persist into adulthood. Therefore, it is essential to identify possible neuronal mechanisms underlying the observed deficits in learning and memory. Hippocampal interneurons play a pivotal role in regulating hippocampus-dependent learning and memory by exerting strong inhibition on excitatory pyramidal cells. The function of these interneurons is regulated not only by synaptic inputs from other types of neurons but is also precisely governed by their own intrinsic membrane ionic conductances. The voltage-gated A-type potassium current (IA ) regulates the intrinsic membrane properties of neurons, and disruption of IA is responsible for many neuropathological processes including learning and memory deficits. Thus, it represents a previously unexplored cellular mechanism whereby chronic ethanol (EtOH) may alter hippocampal memory-related functioning. METHODS Using whole-cell electrophysiological recording methods, we investigated the enduring effects of chronic intermittent ethanol (CIE) exposure during adolescence or adulthood on IA in rat CA1 interneurons. RESULTS We found that the mean peak amplitude of IA was significantly reduced after CIE in either adolescence or adulthood, but IA density was attenuated after CIE in adolescence but not after CIE in adulthood. In addition, the voltage-dependent steady-state activation and inactivation of IA were altered in interneurons after CIE. CONCLUSIONS These findings suggest that CIE can cause long-term changes in IA channels in interneurons and thus may alter their inhibitory influences on memory-related local hippocampal circuits, which could be, in turn, responsible for learning and memory impairments observed after chronic EtOH exposure.
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Affiliation(s)
- Qiang Li
- Durham VA Medical Center , Duke University Medical Center, Durham, North Carolina; Department of Psychiatry , Duke University Medical Center, Durham, North Carolina; Department of Neurosugery , Duke University Medical Center, Durham, North Carolina
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Ih channels prevent overexcitability of early developmental CA1 neurons showing high input resistance in rats. Brain Res Bull 2013; 91:14-20. [DOI: 10.1016/j.brainresbull.2012.11.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 11/23/2012] [Accepted: 11/24/2012] [Indexed: 11/21/2022]
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Jung SC, Eun SY. Sustained K(+) Outward Currents are Sensitive to Intracellular Heteropodatoxin2 in CA1 Neurons of Organotypic Cultured Hippocampi of Rats. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2012; 16:343-8. [PMID: 23118559 PMCID: PMC3484520 DOI: 10.4196/kjpp.2012.16.5.343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 10/05/2012] [Accepted: 10/10/2012] [Indexed: 11/15/2022]
Abstract
Blocking or regulating K+ channels is important for investigating neuronal functions in mammalian brains, because voltage-dependent K+ channels (Kv channels) play roles to regulate membrane excitabilities for synaptic and somatic processings in neurons. Although a number of toxins and chemicals are useful to change gating properties of Kv channels, specific effects of each toxin on a particular Kv subunit have not been sufficiently demonstrated in neurons yet. In this study, we tested electrophysiologically if heteropodatoxin2 (HpTX2), known as one of Kv4-specific toxins, might be effective on various K+ outward currents in CA1 neurons of organotypic hippocampal slices of rats. Using a nucleated-patch technique and a pre-pulse protocol in voltage-clamp mode, total K+ outward currents recorded in the soma of CA1 neurons were separated into two components, transient and sustained currents. The extracellular application of HpTX2 weakly but significantly reduced transient currents. However, when HpTX2 was added to internal solution, the significant reduction of amplitudes were observed in sustained currents but not in transient currents. This indicates the non-specificity of HpTX2 effects on Kv4 family. Compared with the effect of cytosolic 4-AP to block transient currents, it is possible that cytosolic HpTX2 is pharmacologically specific to sustained currents in CA1 neurons. These results suggest that distinctive actions of HpTX2 inside and outside of neurons are very efficient to selectively reduce specific K+ outward currents.
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Affiliation(s)
- Sung-Cherl Jung
- Department of Physiology, School of Medicine, Jeju National University, Jeju 690-756, Korea
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Kiselycznyk C, Hoffman DA, Holmes A. Effects of genetic deletion of the Kv4.2 voltage-gated potassium channel on murine anxiety-, fear- and stress-related behaviors. BIOLOGY OF MOOD & ANXIETY DISORDERS 2012; 2:5. [PMID: 22738428 PMCID: PMC3384232 DOI: 10.1186/2045-5380-2-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Accepted: 03/02/2012] [Indexed: 01/06/2023]
Abstract
Background Potassium channels have been proposed to play a role in mechanisms of neural plasticity, and the Kv4.2 subunit has been implicated in the regulation of action-potential back-propagation to the dendrites. Alterations in mechanisms of plasticity have been further proposed to underlie various psychiatric disorders, but the role of Kv4.2 in anxiety or depression is not well understood. Methods In this paper, we analyzed the phenotype Kv4.2 knockout mice based on their neurological function, on a battery of behaviors including those related to anxiety and depression, and on plasticity-related learning tasks. Results We found a novelty-induced hyperactive phenotype in knockout mice, and these mice also displayed increased reactivity to novel stimulus such as an auditory tone. No clear anxiety- or depression-related phenotype was observed, nor any alterations in learning/plasticity-based paradigms. Conclusions We did not find clear evidence for an involvement of Kv4.2 in neuropsychiatric or plasticity-related phenotypes, but there was support for a role in Kv4.2 in dampening excitatory responses to novel stimuli.
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Affiliation(s)
- Carly Kiselycznyk
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA.
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Naudé J, Paz JT, Berry H, Delord B. A theory of rate coding control by intrinsic plasticity effects. PLoS Comput Biol 2012; 8:e1002349. [PMID: 22275858 PMCID: PMC3261921 DOI: 10.1371/journal.pcbi.1002349] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 11/27/2011] [Indexed: 11/18/2022] Open
Abstract
Intrinsic plasticity (IP) is a ubiquitous activity-dependent process regulating neuronal excitability and a cellular correlate of behavioral learning and neuronal homeostasis. Because IP is induced rapidly and maintained long-term, it likely represents a major determinant of adaptive collective neuronal dynamics. However, assessing the exact impact of IP has remained elusive. Indeed, it is extremely difficult disentangling the complex non-linear interaction between IP effects, by which conductance changes alter neuronal activity, and IP rules, whereby activity modifies conductance via signaling pathways. Moreover, the two major IP effects on firing rate, threshold and gain modulation, remain unknown in their very mechanisms. Here, using extensive simulations and sensitivity analysis of Hodgkin-Huxley models, we show that threshold and gain modulation are accounted for by maximal conductance plasticity of conductance that situate in two separate domains of the parameter space corresponding to sub- and supra-threshold conductance (i.e. activating below or above the spike onset threshold potential). Analyzing equivalent integrate-and-fire models, we provide formal expressions of sensitivities relating to conductance parameters, unraveling unprecedented mechanisms governing IP effects. Our results generalize to the IP of other conductance parameters and allow strong inference for calcium-gated conductance, yielding a general picture that accounts for a large repertoire of experimental observations. The expressions we provide can be combined with IP rules in rate or spiking models, offering a general framework to systematically assess the computational consequences of IP of pharmacologically identified conductance with both fine grain description and mathematical tractability. We provide an example of such IP loop model addressing the important issue of the homeostatic regulation of spontaneous discharge. Because we do not formulate any assumptions on modification rules, the present theory is also relevant to other neural processes involving excitability changes, such as neuromodulation, development, aging and neural disorders. Over the past decades, experimental and theoretical studies of the cellular basis of learning and memory have mainly focused on synaptic plasticity, the experience-dependent modification of synapses. However, behavioral learning has also been correlated with experience-dependent changes of non-synaptic voltage-dependent ion channels. This intrinsic plasticity changes the neuron's propensity to fire action potentials in response to synaptic inputs. Thus a fundamental problem is to relate changes of the neuron input-output function with voltage-gated conductance modifications. Using a sensitivity analysis in biophysically realistic models, we depict a generic dichotomy between two classes of voltage-dependent ion channels. These two classes modify the threshold and the slope of the neuron input-output relation, allowing neurons to regulate the range of inputs they respond to and the gain of that response, respectively. We further provide analytical descriptions that enlighten the dynamical mechanisms underlying these effects and propose a concise and realistic framework for assessing the computational impact of intrinsic plasticity in neuron network models. Our results account for a large repertoire of empirical observations and may enlighten functional changes that characterize development, aging and several neural diseases, which also involve changes in voltage-dependent ion channels.
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Affiliation(s)
- J. Naudé
- Institut des Systèmes Intelligents et de Robotique, CNRS – UMR 7222, Université Pierre et Marie Curie (UPMC), Paris, France
| | - J. T. Paz
- Department of Neurology & Neurological Sciences, Stanford University Medical Center, Stanford, California, United States of America
| | - H. Berry
- Project-Team BEAGLE, INRIA Rhone-Alpes, LIRIS UMR5205, Université de Lyon, Lyon, France
| | - B. Delord
- Institut des Systèmes Intelligents et de Robotique, CNRS – UMR 7222, Université Pierre et Marie Curie (UPMC), Paris, France
- * E-mail:
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Neuronal activity causes rapid changes of lateral amygdala neuronal membrane properties and reduction of synaptic integration and synaptic plasticity in vivo. J Neurosci 2011; 31:6108-20. [PMID: 21508236 DOI: 10.1523/jneurosci.0690-11.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neuronal membrane properties dictate neuronal responsiveness. Plasticity of membrane properties alters neuronal function and can arise in response to robust neuronal activity. Despite the potential for great impact, there is little evidence for a rapid effect of activity-dependent changes of membrane properties on many neuronal functions in vivo in mammalian brain. In this study it was tested whether periods of neuronal firing lead to a rapid change of membrane properties in neurons of a rat brain region important for some forms of learning, the lateral nucleus of the amygdala, using in vivo intracellular recordings. Our results demonstrate that rapid plasticity of membrane properties occurs in vivo, in response to action potential firing. This plasticity of membrane properties leads to changes of synaptic integration and subsequent synaptic plasticity. These changes require Ca(2+) and hyperpolarization-activated ion channels, but are NMDA independent. Furthermore, the parameters and time course of these changes would not have been predicted from most in vitro studies. The plasticity of membrane properties demonstrated here may represent a basic form of in vivo short-term plasticity that modifies neuronal function.
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Jensen CS, Rasmussen HB, Misonou H. Neuronal trafficking of voltage-gated potassium channels. Mol Cell Neurosci 2011; 48:288-97. [PMID: 21627990 DOI: 10.1016/j.mcn.2011.05.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2011] [Revised: 05/01/2011] [Accepted: 05/16/2011] [Indexed: 11/28/2022] Open
Abstract
The computational ability of CNS neurons depends critically on the specific localization of ion channels in the somatodendritic and axonal membranes. Neuronal dendrites receive synaptic inputs at numerous spines and integrate them in time and space. The integration of synaptic potentials is regulated by voltage-gated potassium (Kv) channels, such as Kv4.2, which are specifically localized in the dendritic membrane. The synaptic potentials eventually depolarize the membrane of the axon initial segment, thereby activating voltage-gated sodium channels to generate action potentials. Specific Kv channels localized in the axon initial segment, such as Kv1 and Kv7 channels, determine the shape and the rate of action potentials. Kv1 and Kv7 channels present at or near nodes of Ranvier and in presynaptic terminals also influence the propagation of action potentials and neurotransmitter release. The physiological significance of proper Kv channel localization is emphasized by the fact that defects in the trafficking of Kv channels are observed in several neurological disorders including epilepsy. In this review, we will summarize the current understanding of the mechanisms of Kv channel trafficking and discuss how they contribute to the establishment and maintenance of the specific localization of Kv channels in neurons.
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Affiliation(s)
- Camilla S Jensen
- Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark
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Sabeti J. Ethanol exposure in early adolescence inhibits intrinsic neuronal plasticity via sigma-1 receptor activation in hippocampal CA1 neurons. Alcohol Clin Exp Res 2011; 35:885-904. [PMID: 21314692 PMCID: PMC3083503 DOI: 10.1111/j.1530-0277.2010.01419.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND We demonstrated previously that rats exposed to chronic intermittent ethanol (CIE) vapors in early adolescence show increased magnitudes of long-term potentiation (LTP) of excitatory transmission when recorded at dendritic synapses in hippocampus. Large amplitude LTP following CIE exposure is mediated by sigma-1 receptors; however, not yet addressed is the role of sigma-1 receptors in modulating the intrinsic properties of neurons to alter their action potential firing during LTP. METHODS Activity-induced plasticity of spike firing was investigated using rat hippocampal slice recordings to measure changes in both field excitatory postsynaptic potentials (fEPSPs) and population spikes (pop. spikes) concomitantly at dendritic inputs and soma of CA1 pyramidal neurons, respectively. RESULTS We observed unique modifications in plasticity of action potential firing in hippocampal slices from CIE exposed adolescent rats, where the induction of large amplitude LTP by 100 Hz stimulations was accompanied by reduced CA1 neuronal excitability--reflected as decreased pop. spike efficacy and impaired activity-induced fEPSP-to-spike (E-S) potentiation. In contrast, LTP induction in ethanol-naïve control slices resulted in increased spike efficacy and robust E-S potentiation. E-S potentiation impairments emerged at 24 hours after CIE treatment cessation, but not before the alcohol withdrawal period, and were restored with bath-application of the sigma-1 receptor selective antagonist BD1047, but not the NMDA receptor antagonist d-AP5. Further evidence revealed a significantly shortened somatic fEPSP time course in adolescent CIE-withdrawn hippocampal slices during LTP; however, paired-pulse data show no apparent correspondence between E-S dissociation and altered recurrent feedback inhibition. CONCLUSIONS Results here suggest that acute withdrawal from adolescent CIE exposure triggers sigma-1 receptors that act to depress the efficacy of excitatory inputs in triggering action potentials during LTP. Such withdrawal-induced depression of E-S plasticity in hippocampus probably entails sigma-1 receptor modulation of 1 or several voltage-gated ion channels controlling the neuronal input-output dynamics.
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Affiliation(s)
- Jilla Sabeti
- Department of Molecular and Integrative Neurosciences, The Scripps Research Institute, La Jolla, California, USA.
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35
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Nestor MW, Hoffman DA. Differential cycling rates of Kv4.2 channels in proximal and distal dendrites of hippocampal CA1 pyramidal neurons. Hippocampus 2011; 22:969-80. [PMID: 21472817 DOI: 10.1002/hipo.20899] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2010] [Indexed: 11/06/2022]
Abstract
The heterogeneous expression of voltage-gated channels in dendrites suggests that neurons perform local microdomain computations at different regions. It has been shown that A-type K(+) channels have a nonuniform distribution along the primary apical dendrite in CA1 pyramidal neurons, increasing with distance from the soma. Kv4.2 channels, which are responsible for the somatodendritic A-type K(+) current in CA1 pyramidal neurons, shape local synaptic input, and regulate the back-propagation of APs into dendrites. Experiments were performed to test the hypothesis that Kv4.2 channels are differentially trafficked at different regions along the apical dendrite during basal activity and upon stimulation in CA1 neurons. Proximal (50-150 μm from the soma, primary and oblique) and distal (>200 μm) apical dendrites were selected. The fluorescence recovery after photobleaching (FRAP) technique was used to measure basal cycling rates of EGFP-tagged Kv4.2 (Kv4.2g). We found that the cycling rate of Kv4.2 channels was one order of magnitude slower at both primary and oblique dendrites between 50 and 150 μm from the soma. Kv4.2 channel cycling increased significantly at 200 to 250 μm from the soma. Expression of a Kv4.2 mutant lacking a phosphorylation site for protein kinase-A (Kv4.2gS552A) abolished this distance-dependent change in channel cycling; demonstrating that phosphorylation by PKA underlies the increased mobility in distal dendrites. Neuronal stimulation by α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) treatment increased cycling of Kv4.2 channels significantly at distal sites only. This activity-dependent increase in Kv4.2 cycling at distal dendrites was blocked by expression of Kv4.2gS552A. These results indicate that distance-dependent Kv4.2 mobility is regulated by activity-dependent phosphorylation of Kv4.2 by PKA.
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Affiliation(s)
- Michael W Nestor
- Molecular Neurophysiology and Biophysics Unit, Laboratory of Cellular and Synaptic Neurophysiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892-3715, USA.
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AKAP79/150 impacts intrinsic excitability of hippocampal neurons through phospho-regulation of A-type K+ channel trafficking. J Neurosci 2011; 31:1323-32. [PMID: 21273417 DOI: 10.1523/jneurosci.5383-10.2011] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Kv4.2, as the primary α-subunit of rapidly inactivating, A-type voltage-gated K(+) (Kv) channels expressed in hippocampal CA1 pyramidal dendrites, plays a critical role in regulating their excitability. Activity-dependent trafficking of Kv4.2 relies on C-terminal protein kinase A (PKA) phosphorylation. A-kinase-anchoring proteins (AKAPs) target PKA to glutamate receptor and ion channel complexes to allow for discrete, local signaling. As part of a previous study, we showed that AKAP79/150 interacts with Kv4.2 complexes and that the two proteins colocalize in hippocampal neurons. However, the nature and functional consequence of their interaction has not been previously explored. Here, we report that the C-terminal domain of Kv4.2 interacts with an internal region of AKAP79/150 that overlaps with its MAGUK (membrane-associated guanylate kinase)-binding domain. We show that AKAP79/150-anchored PKA activity controls Kv4.2 surface expression in heterologous cells and hippocampal neurons. Consistent with these findings, disrupting PKA anchoring led to a decrease in neuronal excitability, while preventing dephosphorylation by the phosphatase calcineurin resulted in increased excitability. These results demonstrate that AKAP79/150 provides a platform for dynamic PKA regulation of Kv4.2 expression, fundamentally impacting CA1 excitability.
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van Welie I, du Lac S. Bidirectional control of BK channel open probability by CAMKII and PKC in medial vestibular nucleus neurons. J Neurophysiol 2011; 105:1651-9. [PMID: 21307321 DOI: 10.1152/jn.00058.2011] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Large conductance K(+) (BK) channels are a key determinant of neuronal excitability. Medial vestibular nucleus (MVN) neurons regulate eye movements to ensure image stabilization during head movement, and changes in their intrinsic excitability may play a critical role in plasticity of the vestibulo-ocular reflex. Plasticity of intrinsic excitability in MVN neurons is mediated by kinases, and BK channels influence excitability, but whether endogenous BK channels are directly modulated by kinases is unknown. Double somatic patch-clamp recordings from MVN neurons revealed large conductance potassium channel openings during spontaneous action potential firing. These channels displayed Ca(2+) and voltage dependence in excised patches, identifying them as BK channels. Recording isolated single channel currents at physiological temperature revealed a novel kinase-mediated bidirectional control in the range of voltages over which BK channels are activated. Application of activated Ca(2+)/calmodulin-dependent kinase II (CAMKII) increased BK channel open probability by shifting the voltage activation range towards more hyperpolarized potentials. An opposite shift in BK channel open probability was revealed by inhibition of phosphatases and was occluded by blockade of protein kinase C (PKC), suggesting that active PKC associated with BK channel complexes in patches was responsible for this effect. Accordingly, direct activation of endogenous PKC by PMA induced a decrease in BK open probability. BK channel activity affects excitability in MVN neurons and bidirectional control of BK channels by CAMKII, and PKC suggests that cellular signaling cascades engaged during plasticity may dynamically control excitability by regulating BK channel open probability.
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Affiliation(s)
- Ingrid van Welie
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, San Diego, CA 92037, USA
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Jung SC, Eun SY, Kim J, Hoffman DA. Kv4.2 block of long-term potentiation is partially dependent on synaptic NMDA receptor remodeling. Brain Res Bull 2011; 84:17-21. [PMID: 20920553 PMCID: PMC3496256 DOI: 10.1016/j.brainresbull.2010.09.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 08/24/2010] [Accepted: 09/25/2010] [Indexed: 11/22/2022]
Abstract
Proper expression of synaptic NMDA receptors (NMDARs) is necessary to regulate synaptic Ca²(+) influx and the induction the long-term potentiation (LTP) in the mammalian hippocampus. Previously we reported that expressing the A-type K(+) channel subunit Kv4.2 in CA1 neurons of organotypic slice cultures reduced synaptic NR2B-containing NMDAR expression and completely blocked LTP induced by a pairing protocol. As pretreatment with an NMDAR antagonist (APV) overnight blocked the reduction of NR2B-containing receptors in neurons expressing EGFP-labeled Kv4.2 (Kv4.2g), we hypothesized that LTP would be rescued in Kv4.2g neurons by overnight treatment with APV. We report here that the overnight APV pretreatment in Kv4.2g-expressing neurons only partially restored potentiation. This partial potentiation was completely blocked by inhibition of the CAMKII kinase. These results indicate that A-type K(+) channels must regulate synaptic integration and plasticity through another mechanism in addition to their regulation of synaptic NR2 subunit composition. We suggest that dendritic excitability, which is regulated by Kv4.2 expression, also contributes to synaptic plasticity.
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Affiliation(s)
- Sung-Cherl Jung
- Department of Physiology, Jeju National University, Republic of Korea.
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Visual deprivation suppresses L5 pyramidal neuron excitability by preventing the induction of intrinsic plasticity. Neuron 2011; 68:750-62. [PMID: 21092863 DOI: 10.1016/j.neuron.2010.09.033] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/09/2010] [Indexed: 11/23/2022]
Abstract
In visual cortex monocular deprivation (MD) during a critical period (CP) reduces the ability of the deprived eye to activate cortex, but the underlying cellular plasticity mechanisms are incompletely understood. Here we show that MD reduces the intrinsic excitability of layer 5 (L5) pyramidal neurons and enhances long-term potentiation of intrinsic excitability (LTP-IE). Further, MD and LTP-IE induce reciprocal changes in K(v)2.1 current, and LTP-IE reverses the effects of MD on intrinsic excitability. Taken together these data suggest that MD reduces intrinsic excitability by preventing sensory-drive induced LTP-IE. The effects of MD on excitability were correlated with the classical visual system CP, and (like the functional effects of MD) could be rapidly reversed when vision was restored. These data establish LTP-IE as a candidate mechanism mediating loss of visual responsiveness within L5, and suggest that intrinsic plasticity plays an important role in experience-dependent refinement of visual cortical circuits.
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Martin S, Lino-de-Oliveira C, Joca SRL, Weffort de Oliveira R, Echeverry MB, Da Silva CA, Pardo L, Stühmer W, Bel ED. Eag 1, Eag 2 and Kcnn3 gene brain expression of isolated reared rats. GENES BRAIN AND BEHAVIOR 2010; 9:918-24. [DOI: 10.1111/j.1601-183x.2010.00632.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Shah MM, Hammond RS, Hoffman DA. Dendritic ion channel trafficking and plasticity. Trends Neurosci 2010; 33:307-16. [PMID: 20363038 PMCID: PMC2902701 DOI: 10.1016/j.tins.2010.03.002] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 02/22/2010] [Accepted: 03/04/2010] [Indexed: 11/29/2022]
Abstract
Dendritic ion channels are essential for the regulation of intrinsic excitability as well as modulating the shape and integration of synaptic signals. Changes in dendritic channel function have been associated with many forms of synaptic plasticity. Recent evidence suggests that dendritic ion channel modulation and trafficking could contribute to plasticity-induced alterations in neuronal function. In this review we discuss our current knowledge of dendritic ion channel modulation and trafficking and their relationship to cellular and synaptic plasticity. We also consider the implications for neuronal function. We argue that to gain an insight into neuronal information processing it is essential to understand the regulation of dendritic ion channel expression and properties.
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Affiliation(s)
- Mala M Shah
- Department of Pharmacology, The School of Pharmacy, University of London, London, WC1N 1AX, UK.
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Lin L, Sun W, Wikenheiser AM, Kung F, Hoffman DA. KChIP4a regulates Kv4.2 channel trafficking through PKA phosphorylation. Mol Cell Neurosci 2010; 43:315-25. [PMID: 20045463 DOI: 10.1016/j.mcn.2009.12.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 12/18/2009] [Accepted: 12/22/2009] [Indexed: 10/20/2022] Open
Abstract
Voltage-gated potassium (Kv) channels play important roles in regulating the excitability of myocytes and neurons. Kv4.2 is the primary alpha-subunit of the channel that produces the A-type K(+) current in CA1 pyramidal neurons of the hippocampus, which is critically involved in the regulation of dendritic excitability and plasticity. K(+) channel-interacting proteins, KChIPs (KChIP1-4), associate with the N-terminal of Kv4.2 and modulate the channel's biophysical properties, turnover rate and surface expression. In the present study, we investigated the role of Kv4.2 C-terminal PKA phosphorylation site S552 in the KChIP4a-mediated effects on Kv4.2 channel trafficking. We found that while interaction between Kv4.2 and KChIP4a does not require PKA phosphorylation of Kv4.2(S552), phosphorylation of this site is necessary for both enhanced stabilization and membrane expression of Kv4.2 channel complexes produced by KChIP4a. Enhanced surface expression and protein stability conferred by co-expression of Kv4.2 with other KChIP isoforms did not require PKA phosphorylation of Kv4.2 S552. Finally, we identify A-kinase anchoring proteins (AKAPs) as Kv4.2 binding partners, allowing for discrete local PKA signaling. These data demonstrate that PKA phosphorylation of Kv4.2 plays an important role in the trafficking of Kv4.2 through its specific interaction with KChIP4a.
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Affiliation(s)
- Lin Lin
- Molecular Neurophysiology and Biophysics Unit, Laboratory of Cellular and Synaptic Neurophysiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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