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A novel mechanism for Ca/calmodulin-dependent protein kinase II targeting to L-type Ca channels that initiates long-range signaling to the nucleus.
Wang X, Marks CR, Perfitt TL, Nakagawa T, Lee A, Jacobson DA, Colbran RJ
(2017) J Biol Chem 292: 17324-17336
MeSH Terms: Animals, Calcium Channels, Calcium-Calmodulin-Dependent Protein Kinase Type 2, Cell Nucleus, Female, Hippocampus, Learning, Memory, Neurons, Protein Domains, Rats, Rats, Sprague-Dawley, Signal Transduction
Show Abstract · Added November 13, 2017
Neuronal excitation can induce new mRNA transcription, a phenomenon called excitation-transcription (E-T) coupling. Among several pathways implicated in E-T coupling, activation of voltage-gated L-type Ca channels (LTCCs) in the plasma membrane can initiate a signaling pathway that ultimately increases nuclear CREB phosphorylation and, in most cases, expression of immediate early genes. Initiation of this long-range pathway has been shown to require recruitment of Ca-sensitive enzymes to a nanodomain in the immediate vicinity of the LTCC by an unknown mechanism. Here, we show that activated Ca/calmodulin-dependent protein kinase II (CaMKII) strongly interacts with a novel binding motif in the N-terminal domain of Ca1 LTCC α1 subunits that is not conserved in Ca2 or Ca3 voltage-gated Ca channel subunits. Mutations in the Ca1.3 α1 subunit N-terminal domain or in the CaMKII catalytic domain that largely prevent the interaction also disrupt CaMKII association with intact LTCC complexes isolated by immunoprecipitation. Furthermore, these same mutations interfere with E-T coupling in cultured hippocampal neurons. Taken together, our findings define a novel molecular interaction with the neuronal LTCC that is required for the initiation of a long-range signal to the nucleus that is critical for learning and memory.
© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.
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3 Members
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13 MeSH Terms
A critical period for the trophic actions of leptin on AgRP neurons in the arcuate nucleus of the hypothalamus.
Kamitakahara A, Bouyer K, Wang CH, Simerly R
(2018) J Comp Neurol 526: 133-145
MeSH Terms: Age Factors, Agouti-Related Protein, Analysis of Variance, Animals, Animals, Newborn, Arcuate Nucleus of Hypothalamus, Axons, ELAV-Like Protein 3, Estrogen Receptor alpha, Female, Green Fluorescent Proteins, Integrases, Leptin, Male, Mice, Mice, Inbred C57BL, Mice, Transgenic, Neurons, Neuropeptide Y, Receptors, Leptin, STAT3 Transcription Factor
Show Abstract · Added April 11, 2019
In the developing hypothalamus, the fat-derived hormone leptin stimulates the growth of axons from the arcuate nucleus of the hypothalamus (ARH) to other regions that control energy balance. These projections are significantly reduced in leptin deficient (Lep ) mice and this phenotype is largely rescued by neonatal leptin treatments. However, treatment of mature Lep mice is ineffective, suggesting that the trophic action of leptin is limited to a developmental critical period. To temporally delineate closure of this critical period for leptin-stimulated growth, we treated Lep mice with exogenous leptin during a variety of discrete time periods, and measured the density of Agouti-Related Peptide (AgRP) containing projections from the ARH to the ventral part of the dorsomedial nucleus of the hypothalamus (DMHv), and to the medial parvocellular part of the paraventricular nucleus (PVHmp). The results indicate that leptin loses its neurotrophic potential at or near postnatal day 28. The duration of leptin exposure appears to be important, with 9- or 11-day treatments found to be more effective than shorter (5-day) treatments. Furthermore, leptin treatment for 9 days or more was sufficient to restore AgRP innervation to both the PVHmp and DMHv in Lep females, but only to the DMHv in Lep males. Together, these findings reveal that the trophic actions of leptin are contingent upon timing and duration of leptin exposure, display both target and sex specificity, and that modulation of leptin-dependent circuit formation by each of these factors may carry enduring consequences for feeding behavior, metabolism, and obesity risk.
© 2017 Wiley Periodicals, Inc.
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MeSH Terms
Implications of the N-terminal heterogeneity for the neuronal K-Cl cotransporter KCC2 function.
Markkanen M, Ludwig A, Khirug S, Pryazhnikov E, Soni S, Khiroug L, Delpire E, Rivera C, Airaksinen MS, Uvarov P
(2017) Brain Res 1675: 87-101
MeSH Terms: Amino Acid Sequence, Animals, Female, HEK293 Cells, Humans, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Neurons, Protein Isoforms, Rats, Symporters
Show Abstract · Added April 3, 2018
The neuron-specific K-Cl cotransporter KCC2 maintains the low intracellular chloride concentration required for the fast hyperpolarizing responses of the inhibitory neurotransmitters γ-aminobutyric acid (GABA) and glycine. The two KCC2 isoforms, KCC2a and KCC2b differ by their N-termini as a result of alternative promoter usage. Whereas the role of KCC2b in mediating the chloride transport is unequivocal, the physiological role of KCC2a in neurons has remained obscure. We show that KCC2a isoform can decrease the intracellular chloride concentration in cultured neurons and attenuate calcium responses evoked by application of the GABA receptor agonist muscimol. While the biotinylation assay detected both KCC2 isoforms at the cell surface of cultured neurons, KCC2a was not detected at the plasma membrane in immunostainings, suggesting that the N-terminal KCC2a epitope is masked. Confirming this hypothesis, KCC2a surface expression was detected by the C-terminal KCC2 pan antibody but not by the N-terminal KCC2a antibody in KCC2b-deficient neurons. One possible cause for the epitope masking is the binding site of Ste20-related proline-alanine-rich kinase (SPAK) in the KCC2a N-terminus. SPAK, a known regulator of K-Cl cotransporters, was co-immunoprecipitated in a complex with KCC2a but not KCC2b isoform. Moreover, SPAK overexpression decreased the transport activity of KCC2a but not that of KCC2b, as revealed by rubidium flux assay in HEK293 cells. Thus, our data indicate that both KCC2 isoforms perform as chloride cotransporters in neuronal cells, while their N-terminal heterogeneity could play an important role in fine-tuning of the K-Cl transport activity.
Copyright © 2017 Elsevier B.V. All rights reserved.
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1 Members
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13 MeSH Terms
The Atypical MAP Kinase SWIP-13/ERK8 Regulates Dopamine Transporters through a Rho-Dependent Mechanism.
Bermingham DP, Hardaway JA, Refai O, Marks CR, Snider SL, Sturgeon SM, Spencer WC, Colbran RJ, Miller DM, Blakely RD
(2017) J Neurosci 37: 9288-9304
MeSH Terms: Animals, Animals, Genetically Modified, Caenorhabditis elegans, Caenorhabditis elegans Proteins, Cells, Cultured, Dopamine, Dopamine Plasma Membrane Transport Proteins, Extracellular Signal-Regulated MAP Kinases, Gene Expression Regulation, Enzymologic, Neurons, rho-Associated Kinases
Show Abstract · Added March 21, 2018
The neurotransmitter dopamine (DA) regulates multiple behaviors across phylogeny, with disrupted DA signaling in humans associated with addiction, attention-deficit/ hyperactivity disorder, schizophrenia, and Parkinson's disease. The DA transporter (DAT) imposes spatial and temporal limits on DA action, and provides for presynaptic DA recycling to replenish neurotransmitter pools. Molecular mechanisms that regulate DAT expression, trafficking, and function, particularly , remain poorly understood, though recent studies have implicated rho-linked pathways in psychostimulant action. To identify genes that dictate the ability of DAT to sustain normal levels of DA clearance, we pursued a forward genetic screen in based on the phenotype swimming-induced paralysis (Swip), a paralytic behavior observed in hermaphrodite worms with loss-of-function mutations. Here, we report the identity of , which encodes a highly conserved ortholog of the human atypical MAP kinase ERK8. We present evidence that SWIP-13 acts presynaptically to insure adequate levels of surface DAT expression and DA clearance. Moreover, we provide and evidence supporting a conserved pathway involving SWIP-13/ERK8 activation of Rho GTPases that dictates DAT surface expression and function. Signaling by the neurotransmitter dopamine (DA) is tightly regulated by the DA transporter (DAT), insuring efficient DA clearance after release. Molecular networks that regulate DAT are poorly understood, particularly Using a forward genetic screen in the nematode , we implicate the atypical mitogen activated protein kinase, SWIP-13, in DAT regulation. Moreover, we provide and evidence that SWIP-13, as well as its human counterpart ERK8, regulate DAT surface availability via the activation of Rho proteins. Our findings implicate a novel pathway that regulates DA synaptic availability and that may contribute to risk for disorders linked to perturbed DA signaling. Targeting this pathway may be of value in the development of therapeutics in such disorders.
Copyright © 2017 the authors 0270-6474/17/379288-17$15.00/0.
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2 Members
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11 MeSH Terms
Lef1-dependent hypothalamic neurogenesis inhibits anxiety.
Xie Y, Kaufmann D, Moulton MJ, Panahi S, Gaynes JA, Watters HN, Zhou D, Xue HH, Fung CM, Levine EM, Letsou A, Brennan KC, Dorsky RI
(2017) PLoS Biol 15: e2002257
MeSH Terms: Animals, Anxiety, Behavior, Animal, Biomarkers, Drosophila Proteins, Drosophila melanogaster, Female, Gene Expression Regulation, Genes, Reporter, Humans, Hypothalamus, Lymphoid Enhancer-Binding Factor 1, Male, Mice, Knockout, Mice, Transgenic, Mutation, Nerve Tissue Proteins, Neurogenesis, Neurons, Species Specificity, Transcription Factors, Zebrafish, Zebrafish Proteins
Show Abstract · Added February 14, 2018
While innate behaviors are conserved throughout the animal kingdom, it is unknown whether common signaling pathways regulate the development of neuronal populations mediating these behaviors in diverse organisms. Here, we demonstrate that the Wnt/ß-catenin effector Lef1 is required for the differentiation of anxiolytic hypothalamic neurons in zebrafish and mice, although the identity of Lef1-dependent genes and neurons differ between these 2 species. We further show that zebrafish and Drosophila have common Lef1-dependent gene expression in their respective neuroendocrine organs, consistent with a conserved pathway that has diverged in the mouse. Finally, orthologs of Lef1-dependent genes from both zebrafish and mouse show highly correlated hypothalamic expression in marmosets and humans, suggesting co-regulation of 2 parallel anxiolytic pathways in primates. These findings demonstrate that during evolution, a transcription factor can act through multiple mechanisms to generate a common behavioral output, and that Lef1 regulates circuit development that is fundamentally important for mediating anxiety in a wide variety of animal species.
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1 Members
0 Resources
23 MeSH Terms
Mechanisms Associated With Physical Activity Behavior: Insights From Rodent Experiments.
Roberts MD, Ruegsegger GN, Brown JD, Booth FW
(2017) Exerc Sport Sci Rev 45: 217-222
MeSH Terms: Animals, Behavior, Animal, Dopaminergic Neurons, Motor Activity, Nucleus Accumbens, Rats, Signal Transduction
Show Abstract · Added October 23, 2017
Dopaminergic signaling differences in the nucleus accumbens (NAcc) seemingly predispose rats to adopt different physical activity behaviors. Physical activity behavior also may be regulated through peripheral mechanisms (i.e., muscle and fat derived as well as hormonal signals). We hypothesize that physical activity behavior is regulated by the convergence of central and peripheral mechanisms onto the NAcc.
0 Communities
1 Members
0 Resources
7 MeSH Terms
KCC3 loss-of-function contributes to Andermann syndrome by inducing activity-dependent neuromuscular junction defects.
Bowerman M, Salsac C, Bernard V, Soulard C, Dionne A, Coque E, Benlefki S, Hince P, Dion PA, Butler-Browne G, Camu W, Bouchard JP, Delpire E, Rouleau GA, Raoul C, Scamps F
(2017) Neurobiol Dis 106: 35-48
MeSH Terms: Agenesis of Corpus Callosum, Animals, Carbamazepine, Cells, Cultured, Chlorides, Disease Models, Animal, Mice, Inbred C57BL, Mice, Transgenic, Motor Neurons, Neuromuscular Junction, Neurotransmitter Agents, Peripheral Nervous System Diseases, Presynaptic Terminals, Sodium-Potassium-Exchanging ATPase, Spinal Cord, Symporters, Synaptic Transmission
Show Abstract · Added April 3, 2018
Loss-of-function mutations in the potassium-chloride cotransporter KCC3 lead to Andermann syndrome, a severe sensorimotor neuropathy characterized by areflexia, amyotrophy and locomotor abnormalities. The molecular events responsible for axonal loss remain poorly understood. Here, we establish that global or neuron-specific KCC3 loss-of-function in mice leads to early neuromuscular junction (NMJ) abnormalities and muscular atrophy that are consistent with the pre-synaptic neurotransmission defects observed in patients. KCC3 depletion does not modify chloride handling, but promotes an abnormal electrical activity among primary motoneurons and mislocalization of Na/K-ATPase α1 in spinal cord motoneurons. Moreover, the activity-targeting drug carbamazepine restores Na/K-ATPase α1 localization and reduces NMJ denervation in Slc12a6 mice. We here propose that abnormal motoneuron electrical activity contributes to the peripheral neuropathy observed in Andermann syndrome.
Copyright © 2017 Elsevier Inc. All rights reserved.
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1 Members
0 Resources
17 MeSH Terms
Unexpected Efficacy of a Novel Sodium Channel Modulator in Dravet Syndrome.
Anderson LL, Hawkins NA, Thompson CH, Kearney JA, George AL
(2017) Sci Rep 7: 1682
MeSH Terms: Action Potentials, Animals, Epilepsies, Myoclonic, Ion Channel Gating, Mice, Inbred C57BL, Mice, Knockout, NAV1.1 Voltage-Gated Sodium Channel, NAV1.6 Voltage-Gated Sodium Channel, Neurons, Pyramidal Cells, Pyridines, Seizures, Survival Analysis, Triazoles
Show Abstract · Added October 2, 2018
Dravet syndrome, an epileptic encephalopathy affecting children, largely results from heterozygous loss-of-function mutations in the brain voltage-gated sodium channel gene SCN1A. Heterozygous Scn1a knockout (Scn1a ) mice recapitulate the severe epilepsy phenotype of Dravet syndrome and are an accepted animal model. Because clinical observations suggest conventional sodium channel blocking antiepileptic drugs may worsen the disease, we predicted the phenotype of Scn1a mice would be exacerbated by GS967, a potent, unconventional sodium channel blocker. Unexpectedly, GS967 significantly improved survival of Scn1a mice and suppressed spontaneous seizures. By contrast, lamotrigine exacerbated the seizure phenotype. Electrophysiological recordings of acutely dissociated neurons revealed that chronic GS967-treatment had no impact on evoked action potential firing frequency of interneurons, but did suppress aberrant spontaneous firing of pyramidal neurons and was associated with significantly lower sodium current density. Lamotrigine had no effects on neuronal excitability of either neuron subtype. Additionally, chronically GS967-treated Scn1a mice exhibited normalized pyramidal neuron sodium current density and reduced hippocampal Na1.6 protein levels, whereas lamotrigine treatment had no effect on either pyramidal neuron sodium current or hippocampal Na1.6 levels. Our findings demonstrate unexpected efficacy of a novel sodium channel blocker in Dravet syndrome and suggest a potential mechanism involving a secondary change in Na1.6.
1 Communities
0 Members
0 Resources
14 MeSH Terms
High spatial correspondence at a columnar level between activation and resting state fMRI signals and local field potentials.
Shi Z, Wu R, Yang PF, Wang F, Wu TL, Mishra A, Chen LM, Gore JC
(2017) Proc Natl Acad Sci U S A 114: 5253-5258
MeSH Terms: Animals, Brain, Brain Mapping, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Neurons, Neurovascular Coupling, Reproducibility of Results, Rest, Saimiri, Somatosensory Cortex
Show Abstract · Added May 4, 2017
Although blood oxygenation level-dependent (BOLD) fMRI has been widely used to map brain responses to external stimuli and to delineate functional circuits at rest, the extent to which BOLD signals correlate spatially with underlying neuronal activity, the spatial relationships between stimulus-evoked BOLD activations and local correlations of BOLD signals in a resting state, and whether these spatial relationships vary across functionally distinct cortical areas are not known. To address these critical questions, we directly compared the spatial extents of stimulated activations and the local profiles of intervoxel resting state correlations for both high-resolution BOLD at 9.4 T and local field potentials (LFPs), using 98-channel microelectrode arrays, in functionally distinct primary somatosensory areas 3b and 1 in nonhuman primates. Anatomic images of LFP and BOLD were coregistered within 0.10 mm accuracy. We found that the point spread functions (PSFs) of BOLD and LFP responses were comparable in the stimulus condition, and both estimates of activations were slightly more spatially constrained than local correlations at rest. The magnitudes of stimulus responses in area 3b were stronger than those in area 1 and extended in a medial to lateral direction. In addition, the reproducibility and stability of stimulus-evoked activation locations within and across both modalities were robust. Our work suggests that the intrinsic resolution of BOLD is not a limiting feature in practice and approaches the intrinsic precision achievable by multielectrode electrophysiology.
0 Communities
2 Members
0 Resources
11 MeSH Terms
Chloride Dysregulation, Seizures, and Cerebral Edema: A Relationship with Therapeutic Potential.
Glykys J, Dzhala V, Egawa K, Kahle KT, Delpire E, Staley K
(2017) Trends Neurosci 40: 276-294
MeSH Terms: Animals, Brain Edema, Brain Injuries, Traumatic, Chlorides, Extracellular Matrix, Humans, Neurons, Seizures, Symporters
Show Abstract · Added May 3, 2017
Pharmacoresistant seizures and cytotoxic cerebral edema are serious complications of ischemic and traumatic brain injury. Intraneuronal Cl concentration ([Cl]) regulation impacts on both cell volume homeostasis and Cl-permeable GABA receptor-dependent membrane excitability. Understanding the pleiotropic molecular determinants of neuronal [Cl] - cytoplasmic impermeant anions, polyanionic extracellular matrix (ECM) glycoproteins, and plasmalemmal Cl transporters - could help the identification of novel anticonvulsive and neuroprotective targets. The cation/Cl cotransporters and ECM metalloproteinases may be particularly druggable targets for intervention. We establish here a paradigm that accounts for recent data regarding the complex regulatory mechanisms of neuronal [Cl] and how these mechanisms impact on neuronal volume and excitability. We propose approaches to modulate [Cl] that are relevant for two common clinical sequela of brain injury: edema and seizures.
Copyright © 2017 Elsevier Ltd. All rights reserved.
0 Communities
1 Members
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9 MeSH Terms