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Lei M, Xu J, Gao Q, Minobe E, Kameyama M, Hao L. PKA phosphorylation of Cav1.2 channel modulates the interaction of calmodulin with the C terminal tail of the channel. J Pharmacol Sci 2018; 137:187-194. [PMID: 30042022 DOI: 10.1016/j.jphs.2018.05.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/18/2018] [Accepted: 05/28/2018] [Indexed: 11/16/2022] Open
Abstract
Activity of cardiac Cav1.2 channels is enhanced by cyclic AMP-PKA signaling. In this study, we studied the effects of PKA phosphorylation on the binding of calmodulin to the fragment peptide of the proximal C-terminal tail of α1C subunit (CT1, a.a. 1509-1789 of guinea-pig). In the pull-down assay, in vitro PKA phosphorylation significantly decreased calmodulin binding to CT1 (61%) at high [Ca2+]. The phosphoresistant (CT1SA) and phosphomimetic (CT1SD) CT1 mutants, in which three PKA sites (Ser1574, 1626, 1699) were mutated to Ala and Asp, respectively, bound with calmodulin with 99% and 65% amount, respectively, compared to that of wild-type CT1. In contrast, at low [Ca2+], calmodulin-binding to CT1SD was higher (33-35%) than that to CT1SA. The distal C-terminal region of α1C (CT3, a.a. 1942-2169) is known to interact with CT1 and inhibit channel activity. CT3 bound to CT1SD was also significantly less than that to CT1SA. In inside-out patch, PKA catalytic subunit (PKAc) facilitated Ca2+ channel activity at both high and low Ca2+ condition. Altogether, these results support the hypothesis that PKA phosphorylation may enhance channel activity and attenuate the Ca2+-dependent inactivation, at least partially, by modulating calmodulin-CT1 interaction both directly and indirectly via CT3-CT1 interaction.
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Affiliation(s)
- Ming Lei
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, 110122, China; Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan
| | - Jianjun Xu
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan.
| | - Qinghua Gao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, 110122, China; Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan
| | - Masaki Kameyama
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, 110122, China.
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Kim YS, Kim YB, Kim WB, Lee SW, Oh SB, Han HC, Lee CJ, Colwell CS, Kim YI. Histamine 1 receptor-Gβγ-cAMP/PKA-CFTR pathway mediates the histamine-induced resetting of the suprachiasmatic circadian clock. Mol Brain 2016; 9:49. [PMID: 27153809 PMCID: PMC4858891 DOI: 10.1186/s13041-016-0227-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 04/15/2016] [Indexed: 11/29/2022] Open
Abstract
Background Recent evidence indicates that histamine, acting on histamine 1 receptor (H1R), resets the circadian clock in the mouse suprachiasmatic nucleus (SCN) by increasing intracellular Ca2+ concentration ([Ca2+]i) through the activation of CaV1.3 L-type Ca2+ channels and Ca2+-induced Ca2+ release from ryanodine receptor-mediated internal stores. Results In the current study, we explored the underlying mechanisms with various techniques including Ca2+- and Cl−-imaging and extracellular single-unit recording. Our hypothesis was that histamine causes Cl− efflux through cystic fibrosis transmembrane conductance regulator (CFTR) to elicit membrane depolarization needed for the activation of CaV1.3 Ca2+ channels in SCN neurons. We found that histamine elicited Cl− efflux and increased [Ca2+]i in dissociated mouse SCN cells. Both of these events were suppressed by bumetanide [Na+-K+-2Cl− cotransporter isotype 1 (NKCC1) blocker], CFTRinh-172 (CFTR inhibitor), gallein (Gβγ protein inhibitor) and H89 [protein kinase A (PKA) inhibitor]. By itself, H1R activation with 2-pyridylethylamine increased the level of cAMP in the SCN and this regulation was prevented by gallein. Finally, histamine-evoked phase shifts of the circadian neural activity rhythm in the mouse SCN slice were blocked by bumetanide, CFTRinh-172, gallein or H89 and were not observed in NKCC1 or CFTR KO mice. Conclusions Taken together, these results indicate that histamine recruits the H1R-Gβγ-cAMP/PKA pathway in the SCN neurons to activate CaV1.3 channels through CFTR-mediated Cl− efflux and ultimately to phase-shift the circadian clock. This pathway and NKCC1 may well be potential targets for agents designed to treat problems resulting from the disturbance of the circadian system.
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Affiliation(s)
- Yoon Sik Kim
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, 126-1 Anam-dong 5-ga, Seoul, 136-705, Republic of Korea.,Department of Psychiatry & Biobehavioral Sciences, University of California-Los Angeles, 760 Westwood Plaza, Los Angeles, CA, 90024, USA
| | - Young-Beom Kim
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, 126-1 Anam-dong 5-ga, Seoul, 136-705, Republic of Korea
| | - Woong Bin Kim
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, 126-1 Anam-dong 5-ga, Seoul, 136-705, Republic of Korea
| | - Seung Won Lee
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, 126-1 Anam-dong 5-ga, Seoul, 136-705, Republic of Korea
| | - Seog Bae Oh
- Pain Cognitive Function Research Center, Dental Research Institute and Department of Neurobiology and Physiology, Seoul National University, Seoul, 110-749, Republic of Korea
| | - Hee-Chul Han
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, 126-1 Anam-dong 5-ga, Seoul, 136-705, Republic of Korea
| | - C Justin Lee
- Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology, Seoul, 136-791, Republic of Korea.
| | - Christopher S Colwell
- Department of Psychiatry & Biobehavioral Sciences, University of California-Los Angeles, 760 Westwood Plaza, Los Angeles, CA, 90024, USA
| | - Yang In Kim
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, 126-1 Anam-dong 5-ga, Seoul, 136-705, Republic of Korea.
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3
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Bista P, Cerina M, Ehling P, Leist M, Pape HC, Meuth SG, Budde T. The role of two-pore-domain background K⁺ (K₂p) channels in the thalamus. Pflugers Arch 2014; 467:895-905. [PMID: 25346156 DOI: 10.1007/s00424-014-1632-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 10/09/2014] [Accepted: 10/12/2014] [Indexed: 12/15/2022]
Abstract
The thalamocortical system is characterized by two fundamentally different activity states, namely synchronized burst firing and tonic action potential generation, which mainly occur during the behavioral states of sleep and wakefulness, respectively. The switch between the two firing modes is crucially governed by the bidirectional modulation of members of the K2P channel family, namely tandem of P domains in a weakly inward rectifying K(+) (TWIK)-related acid-sensitive K(+) (TASK) and TWIK-related K(+) (TREK) channels, in thalamocortical relay (TC) neurons. Several physicochemical stimuli including neurotransmitters, protons, di- and multivalent cations as well as clinically used drugs have been shown to modulate K2P channels in these cells. With respect to modulation of these channels by G-protein-coupled receptors, PLCβ plays a unique role with both substrate breakdown and product synthesis exerting important functions. While the degradation of PIP2 leads to the closure of TREK channels, the production of DAG induces the inhibition of TASK channels. Therefore, TASK and TREK channels were found to be central elements in the control of thalamic activity modes. Since research has yet focused on identifying the muscarinic pathway underling the modulation of TASK and TREK channels in TC neurons, future studies should address other thalamic cell types and members of the K2P channel family.
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Affiliation(s)
- Pawan Bista
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, 48149, Münster, Germany
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Regionally specific expression of high-voltage-activated calcium channels in thalamic nuclei of epileptic and non-epileptic rats. Mol Cell Neurosci 2014; 61:110-22. [PMID: 24914823 DOI: 10.1016/j.mcn.2014.06.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 05/30/2014] [Accepted: 06/05/2014] [Indexed: 11/21/2022] Open
Abstract
The polygenic origin of generalized absence epilepsy results in dysfunction of ion channels that allows the switch from physiological asynchronous to pathophysiological highly synchronous network activity. Evidence from rat and mouse models of absence epilepsy indicates that altered Ca(2+) channel activity contributes to cellular and network alterations that lead to seizure activity. Under physiological circumstances, high voltage-activated (HVA) Ca(2+) channels are important in determining the thalamic firing profile. Here, we investigated a possible contribution of HVA channels to the epileptic phenotype using a rodent genetic model of absence epilepsy. In this study, HVA Ca(2+) currents were recorded from neurons of three different thalamic nuclei that are involved in both sensory signal transmission and rhythmic-synchronized activity during epileptic spike-and-wave discharges (SWD), namely the dorsal part of the lateral geniculate nucleus (dLGN), the ventrobasal thalamic complex (VB) and the reticular thalamic nucleus (NRT) of epileptic Wistar Albino Glaxo rats from Rijswijk (WAG/Rij) and non-epileptic August Copenhagen Irish (ACI) rats. HVA Ca(2+) current densities in dLGN neurons were significantly increased in epileptic rats compared with non-epileptic controls while other thalamic regions revealed no differences between the strains. Application of specific channel blockers revealed that the increased current was carried by L-type Ca(2+) channels. Electrophysiological evidence of increased L-type current correlated with up-regulated mRNA and protein expression of a particular L-type channel, namely Cav1.3, in dLGN of epileptic rats. No significant changes were found for other HVA Ca(2+) channels. Moreover, pharmacological inactivation of L-type Ca(2+) channels results in altered firing profiles of thalamocortical relay (TC) neurons from non-epileptic rather than from epileptic rats. While HVA Ca(2+) channels influence tonic and burst firing in ACI and WAG/Rij differently, it is discussed that increased Cav1.3 expression may indirectly contribute to increased robustness of burst firing and thereby the epileptic phenotype of absence epilepsy.
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5
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The systemic administration of oleoylethanolamide exerts neuroprotection of the nigrostriatal system in experimental Parkinsonism. Int J Neuropsychopharmacol 2014; 17:455-68. [PMID: 24169105 DOI: 10.1017/s1461145713001259] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Oleoylethanolamide (OEA) is an agonist of the peroxisome proliferator-activated receptor α (PPARα) and has been described to exhibit neuroprotective properties when administered locally in animal models of several neurological disorder models, including stroke and Parkinson's disease. However, there is little information regarding the effectiveness of systemic administration of OEA on Parkinson's disease. In the present study, OEA-mediated neuroprotection has been tested on in vivo and in vitro models of 6-hydroxydopamine (6-OH-DA)-induced degeneration. The in vivo model was based on the intrastriatal infusion of the neurotoxin 6-OH-DA, which generates Parkinsonian symptoms. Rats were treated 2 h before and after the 6-OH-DA treatment with systemic OEA (0.5, 1, and 5 mg/kg). The Parkinsonian symptoms were evaluated at 1 and 4 wk after the development of lesions. The functional status of the nigrostriatal system was studied through tyrosine-hydroxylase (TH) and hemeoxygenase-1 (HO-1, oxidation marker) immunostaining as well as by monitoring the synaptophysin content. In vitro cell cultures were also treated with OEA and 6-OH-DA. As expected, our results revealed 6-OH-DA induced neurotoxicity and behavioural deficits; however, these alterations were less severe in the animals treated with the highest dose of OEA (5 mg/kg). 6-OH-DA administration significantly reduced the striatal TH-immunoreactivity (ir) density, synaptophysin expression, and the number of nigral TH-ir neurons. Moreover, 6-OH-DA enhanced striatal HO-1 content, which was blocked by OEA (5 mg/kg). In vitro, 0.5 and 1 μM of OEA exerted significant neuroprotection on cultured nigral neurons. These effects were abolished after blocking PPARα with the selective antagonist GW6471. In conclusion, systemic OEA protects the nigrostriatal circuit from 6-OH-DA-induced neurotoxicity through a PPARα-dependent mechanism.
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DiNuzzo M, Mangia S, Maraviglia B, Giove F. Regulatory mechanisms for glycogenolysis and K+ uptake in brain astrocytes. Neurochem Int 2013; 63:458-64. [PMID: 23968961 DOI: 10.1016/j.neuint.2013.08.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 08/05/2013] [Accepted: 08/07/2013] [Indexed: 11/29/2022]
Abstract
Recent advances in brain energy metabolism support the notion that glycogen in astrocytes is necessary for the clearance of neuronally-released K(+) from the extracellular space. However, how the multiple metabolic pathways involved in K(+)-induced increase in glycogen turnover are regulated is only partly understood. Here we summarize the current knowledge about the mechanisms that control glycogen metabolism during enhanced K(+) uptake. We also describe the action of the ubiquitous Na(+)/K(+) ATPase for both ion transport and intracellular signaling cascades, and emphasize its importance in understanding the complex relation between glycogenolysis and K(+) uptake.
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Affiliation(s)
- Mauro DiNuzzo
- MARBILab, Museo storico della fisica e Centro di studi e ricerche "Enrico Fermi", Rome, Italy.
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7
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Localized calcineurin confers Ca2+-dependent inactivation on neuronal L-type Ca2+ channels. J Neurosci 2013; 32:15328-37. [PMID: 23115171 DOI: 10.1523/jneurosci.2302-12.2012] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Excitation-driven entry of Ca(2+) through L-type voltage-gated Ca(2+) channels controls gene expression in neurons and a variety of fundamental activities in other kinds of excitable cells. The probability of opening of Ca(V)1.2 L-type channels is subject to pronounced enhancement by cAMP-dependent protein kinase (PKA), which is scaffolded to Ca(V)1.2 channels by A-kinase anchoring proteins (AKAPs). Ca(V)1.2 channels also undergo negative autoregulation via Ca(2+)-dependent inactivation (CDI), which strongly limits Ca(2+) entry. An abundance of evidence indicates that CDI relies upon binding of Ca(2+)/calmodulin (CaM) to an isoleucine-glutamine motif in the carboxy tail of Ca(V)1.2 L-type channels, a molecular mechanism seemingly unrelated to phosphorylation-mediated channel enhancement. But our work reveals, in cultured hippocampal neurons and a heterologous expression system, that the Ca(2+)/CaM-activated phosphatase calcineurin (CaN) is scaffolded to Ca(V)1.2 channels by the neuronal anchoring protein AKAP79/150, and that overexpression of an AKAP79/150 mutant incapable of binding CaN (ΔPIX; CaN-binding PXIXIT motif deleted) impedes CDI. Interventions that suppress CaN activity-mutation in its catalytic site, antagonism with cyclosporine A or FK506, or intracellular perfusion with a peptide mimicking the sequence of the phosphatase's autoinhibitory domain-interfere with normal CDI. In cultured hippocampal neurons from a ΔPIX knock-in mouse, CDI is absent. Results of experiments with the adenylyl cyclase stimulator forskolin and with the PKA inhibitor PKI suggest that Ca(2+)/CaM-activated CaN promotes CDI by reversing channel enhancement effectuated by kinases such as PKA. Hence, our investigation of AKAP79/150-anchored CaN reconciles the CaM-based model of CDI with an earlier, seemingly contradictory model based on dephosphorylation signaling.
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Ehling P, Cerina M, Meuth P, Kanyshkova T, Bista P, Coulon P, Meuth SG, Pape HC, Budde T. Ca(2+)-dependent large conductance K(+) currents in thalamocortical relay neurons of different rat strains. Pflugers Arch 2012. [PMID: 23207578 DOI: 10.1007/s00424-012-1188-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Mutations in genes coding for Ca(2+) channels were found in patients with childhood absence epilepsy (CAE) indicating a contribution of Ca(2+)-dependent mechanisms to the generation of spike-wave discharges (SWD) in humans. Since the involvement of Ca(2+) signals remains unclear, the aim of the present study was to elucidate the function of a Ca(2+)-dependent K(+) channel (BKCa) under physiological conditions and in the pathophysiological state of CAE. The activation of BKCa channels is dependent on both voltage and intracellular Ca(2+) concentrations. Moreover, these channels exhibit an outstandingly high level of regulatory heterogeneity that builds the basis for the influence of BKCa channels on different aspects of neuronal activity. Here, we analyse the contribution of BKCa channels to firing of thalamocortical relay neurons, and we test the hypothesis that BKCa channel activity affects the phenotype of a genetic rat model of CAE. We found that the activation of the β2-adrenergic receptor/protein kinase A pathway resulted in BKCa channel inhibition. Furthermore, BKCa channels affect the number of action potentials fired in a burst and produced spike frequency adaptation during tonic activity. The latter result was confirmed by a computer modelling approach. We demonstrate that the β2-adrenergic inhibition of BKCa channels prevents spike frequency adaptation and, thus, might significantly support the tonic firing mode of thalamocortical relay neurons. In addition, we show that BKCa channel functioning differs in epileptic WAG/Rij and thereby likely contributes to highly synchronised, epileptic network activity.
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Affiliation(s)
- Petra Ehling
- Institute of Physiology I, University of Münster, Robert-Koch-Str. 27a, Münster, Germany.
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9
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Ca²⁺-dependent regulation of Ca²⁺ currents in rat primary afferent neurons: role of CaMKII and the effect of injury. J Neurosci 2012; 32:11737-49. [PMID: 22915116 DOI: 10.1523/jneurosci.0983-12.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Currents through voltage-gated Ca²⁺ channels (I(Ca)) may be regulated by cytoplasmic Ca²⁺ levels ([Ca²⁺](c)), producing Ca²⁺-dependent inactivation (CDI) or facilitation (CDF). Since I(Ca) regulates sensory neuron excitability, altered CDI or CDF could contribute to pain generation after peripheral nerve injury. We explored this by manipulating [Ca²⁺](c) while recording I(Ca) in rat sensory neurons. In uninjured neurons, elevating [Ca²⁺](c) with a conditioning prepulse (-15 mV, 2 s) inactivated I(Ca) measured during subsequent test pulses (-15 mV, 5 ms). This inactivation was Ca²⁺-dependent (CDI), since it was decreased with elimination of Ca²⁺ influx by depolarization to above the I(Ca) reversal potential, with high intracellular Ca²⁺ buffering (EGTA 10 mm or BAPTA 20 mm), and with substitution of Ba²⁺ for extracellular Ca²⁺, revealing a residual voltage-dependent inactivation. At longer latencies after conditioning (>6 s), I(Ca) recovered beyond baseline. This facilitation also proved to be Ca²⁺-dependent (CDF) using the protocols limiting cytoplasmic Ca²⁺ elevation. Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) blockers applied by bath (KN-93, myristoyl-AIP) or expressed selectively in the sensory neurons (AIP) reduced CDF, unlike their inactive analogues. Protein kinase C inhibition (chelerythrine) had no effect. Selective blockade of N-type Ca²⁺ channels eliminated CDF, whereas L-type channel blockade had no effect. Following nerve injury, CDI was unaffected, but CDF was eliminated in axotomized neurons. Excitability of sensory neurons in intact ganglia from control animals was diminished after a similar conditioning pulse, but this regulation was eliminated by injury. These findings indicate that I(Ca) in sensory neurons is subject to both CDI and CDF, and that hyperexcitability following injury-induced loss of CDF may result from diminished CaMKII activity.
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The role of a voltage-dependent Ca2+ channel intracellular linker: a structure-function analysis. J Neurosci 2012; 32:7602-13. [PMID: 22649239 DOI: 10.1523/jneurosci.5727-11.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Voltage-dependent calcium channels (VDCCs) allow the passage of Ca(2+) ions through cellular membranes in response to membrane depolarization. The channel pore-forming subunit, α1, and a regulatory subunit (Ca(V)β) form a high affinity complex where Ca(V)β binds to a α1 interacting domain in the intracellular linker between α1 membrane domains I and II (I-II linker). We determined crystal structures of Ca(V)β2 functional core in complex with the Ca(V)1.2 and Ca(V)2.2 I-II linkers to a resolution of 1.95 and 2.0 Å, respectively. Structural differences between the highly conserved linkers, important for coupling Ca(V)β to the channel pore, guided mechanistic functional studies. Electrophysiological measurements point to the importance of differing linker structure in both Ca(V)1 and 2 subtypes with mutations affecting both voltage- and calcium-dependent inactivation and voltage dependence of activation. These linker effects persist in the absence of Ca(V)β, pointing to the intrinsic role of the linker in VDCC function and suggesting that I-II linker structure can serve as a brake during inactivation.
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Ehling P, Kanyshkova T, Baumann A, Landgraf P, Meuth SG, Pape HC, Budde T. Adenylyl cyclases: expression in the developing rat thalamus and their role in absence epilepsy. J Mol Neurosci 2012; 48:45-52. [PMID: 22531884 DOI: 10.1007/s12031-012-9767-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 03/30/2012] [Indexed: 11/27/2022]
Abstract
Adenylyl cyclases (ACs) synthesize the second messenger cyclic AMP (cAMP) which influences the function of multiple ion channels. Former studies point to a malfunction of cAMP-dependent ion channel regulation in thalamocortical relay neurons that contribute to the development of the absence epileptic phenotype of a rat genetic model (WAG/Rij). Here, we provide detailed information about the thalamic gene and protein expression of Ca(2+)/calmodulin-activated AC isoforms in rat thalamus. Data from WAG/Rij were compared to those from non-epileptic controls (August-Copenhagen Irish rats) to elucidate whether differential expression of ACs contributes to the dysregulation of thalamocortical activity. At one postnatal stage (P21), we found the gene expression of two specific Ca(2+)-activated AC isoforms (AC-1 and AC-3) to be significantly down-regulated in epileptic tissue, and we identified the isoform AC-1 to be the most prominent one in both strains. However, Western blot data and analysis of enzymatic AC activity revealed no differences between the two strains. While basal AC activity was low, cAMP production was boosted by application of a forskolin derivative up to sevenfold. Despite previous hints pointing to a major contribution of ACs, the presented data show that there is no apparent causality between AC activity and the occurrence of the epileptic phenotype.
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Affiliation(s)
- Petra Ehling
- Neurology Clinic-Inflammatory Disorders of the Nervous System and Neurooncology, and Institute of Physiology I - Neuropathophysiology, Westfälische Wilhelms-University, ICB, Mendelstr. 7, 48149, Muenster, Germany.
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12
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Rankovic V, Landgraf P, Kanyshkova T, Ehling P, Meuth SG, Kreutz MR, Budde T, Munsch T. Modulation of calcium-dependent inactivation of L-type Ca2+ channels via β-adrenergic signaling in thalamocortical relay neurons. PLoS One 2011; 6:e27474. [PMID: 22164209 PMCID: PMC3229489 DOI: 10.1371/journal.pone.0027474] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 10/17/2011] [Indexed: 01/01/2023] Open
Abstract
Neuronal high-voltage-activated (HVA) Ca(2+) channels are rapidly inactivated by a mechanism that is termed Ca(2+)-dependent inactivation (CDI). In this study we have shown that β-adrenergic receptor (βAR) stimulation inhibits CDI in rat thalamocortical (TC) relay neurons. This effect can be blocked by inhibition of cAMP-dependent protein kinase (PKA) with a cell-permeable inhibitor (myristoylated protein kinase inhibitor-(14-22)-amide) or A-kinase anchor protein (AKAP) St-Ht31 inhibitory peptide, suggesting a critical role of these molecules downstream of the receptor. Moreover, inhibition of protein phosphatases (PP) with okadaic acid revealed the involvement of phosphorylation events in modulation of CDI after βAR stimulation. Double fluorescence immunocytochemistry and pull down experiments further support the idea that modulation of CDI in TC neurons via βAR stimulation requires a protein complex consisting of Ca(V)1.2, PKA and proteins from the AKAP family. All together our data suggest that AKAPs mediate targeting of PKA to L-type Ca(2+) channels allowing their phosphorylation and thereby modulation of CDI.
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Affiliation(s)
- Vladan Rankovic
- Institute of Physiology, Otto-von-Guericke University Magdeburg, Germany.
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Hsu CL, Yang HW, Yen CT, Min MY. Comparison of synaptic transmission and plasticity between sensory and cortical synapses on relay neurons in the ventrobasal nucleus of the rat thalamus. J Physiol 2010; 588:4347-63. [PMID: 20855435 DOI: 10.1113/jphysiol.2010.192864] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Relay neurons in the ventrobasal nucleus of the thalamus transmit somatosensory information to the cerebral cortex and receive sensory and cortical (feedback) synaptic inputs via, respectively, medial lemniscal (ML) and corticothalamic (CT) fibres. Here, we report that calcium-permeable AMPA receptors are expressed at CT synapses, but not ML synapses, and that the NMDA receptor (NMDAR)-mediated/non-NMDAR-mediated synaptic current ratio is significantly larger at CT synapses than at ML synapses. Moreover, NMDAR-dependent LTP and L-type voltage-gated calcium channel-dependent LTD are readily induced at CT synapses, but not ML synapses. In particular, LTD of CT synaptic transmission is induced by spiking of postsynaptic relay neurons in continuous mode, but not burst mode, in current-clamp recordings. These results show that the strength of the cortical input to thalamic relay neurons is selectively subjected to use-dependent modification, which could be a mechanism for regulation of thalamocortical-corticothalamic interactions and the underlying sensory processing.
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Affiliation(s)
- Ching-Lung Hsu
- Institute of Zoology, National Taiwan University, No.1, Roosevelt Road, Section 4, Taipei 106, Taiwan
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Rankovic V, Ehling P, Coulon P, Landgraf P, Kreutz MR, Munsch T, Budde T. Intracellular Ca2+release-dependent inactivation of Ca2+currents in thalamocortical relay neurons. Eur J Neurosci 2010; 31:439-49. [DOI: 10.1111/j.1460-9568.2010.07081.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Coulon P, Herr D, Kanyshkova T, Meuth P, Budde T, Pape HC. Burst discharges in neurons of the thalamic reticular nucleus are shaped by calcium-induced calcium release. Cell Calcium 2009; 46:333-46. [PMID: 19913909 DOI: 10.1016/j.ceca.2009.09.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 09/01/2009] [Accepted: 09/27/2009] [Indexed: 11/18/2022]
Abstract
The nucleus reticularis thalami (NRT) is a layer of inhibitory neurons that surrounds the dorsal thalamus. It appears to be the 'pacemaker' of certain forms of slow oscillations in the thalamus and was proposed to be a key determinant of the internal attentional searchlight as well as the origin of hypersynchronous activity during absence seizures. Neurons of the NRT exhibit a transient depolarization termed low threshold spike (LTS) following sustained hyperpolarization. This is caused by the activation of low-voltage-activated Ca2+ channels (LVACC). Although the role of these channels in thalamocortical oscillations was studied in great detail, little is known about the downstream intracellular Ca2+ signalling pathways and their feedback onto the oscillations. A signalling triad consisting of the sarco(endo)plasmic reticulum calcium ATPase (SERCA), Ca2+ activated K+ channels (SK2), and LVACC is active in dendrites of NRT neurons and shapes rhythmic oscillations. The aim of our study was to find out (i) if and how Ca2+-induced Ca2+ release (CICR) via ryanodine receptors (RyR) can be evoked in NRT neurons and (ii) how the released Ca2+ affects burst activity. Combining electrophysiological, immunohistochemical, and two-photon Ca2+ imaging techniques, we show that CICR in NRT neurons takes place by a cell-type specific coupling of LVACC and RyR. CICR could be evoked by the application of caffeine, by activation of LVACC, or by repetitive LTS generation. During the latter, CICR contributed 30% to the resulting build-up of [Ca2+]i. CICR was abolished by cyclopiazonic acid, a specific blocker for SERCA, or by high concentrations of ryanodine (50 microM). Unlike other thalamic nuclei, in the NRT the activation of high-voltage-activated Ca2+ channels failed to evoke CICR. While action potentials contributed little to the build-up of [Ca2+]i upon repetitive LTS generation, the Ca2+ released via RyR significantly reduced the number of action potentials during an LTS and reduced the neurons' low threshold activity, thus potentially reducing hypersynchronicity. This effect persisted in the presence of the SK2 channel blocker apamin. We conclude that the activation of LVACC specifically causes CICR via RyR in neurons of the NRT, thereby adding a Ca2+-dependent intracellular route to the mechanisms determining rhythmic oscillatory bursting in this nucleus.
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Affiliation(s)
- Philippe Coulon
- Institut für Physiologie I, Westfälische Wilhelms-Universität Münster, Robert-Koch-Str. 27a, 48149 Münster, Germany.
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16
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Johnson MD, McIntyre CC. Quantifying the neural elements activated and inhibited by globus pallidus deep brain stimulation. J Neurophysiol 2008; 100:2549-63. [PMID: 18768645 DOI: 10.1152/jn.90372.2008] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Deep brain stimulation (DBS) of the globus pallidus pars interna (GPi) is an effective therapy option for controlling the motor symptoms of medication-refractory Parkinson's disease and dystonia. Despite the clinical successes of GPi DBS, the precise therapeutic mechanisms are unclear and questions remain on the optimal electrode placement and stimulation parameter selection strategies. In this study, we developed a three-dimensional computational model of GPi-DBS in nonhuman primates to investigate how membrane channel dynamics, synaptic inputs, and axonal collateralization contribute to the neural responses generated during stimulation. We focused our analysis on three general neural elements that surround GPi-DBS electrodes: GPi somatodendritic segments, GPi efferent axons, and globus pallidus pars externa (GPe) fibers of passage. During high-frequency electrical stimulation (136 Hz), somatic activity in the GPi showed interpulse excitatory phases at 1-3 and 4-5.5 ms. When including stimulation-induced GABA(A) and AMPA receptor dynamics into the model, the somatic firing patterns continued to be entrained to the stimulation, but the overall firing rate was reduced (78.7 to 25.0 Hz, P < 0.001). In contrast, axonal output from GPi neurons remained largely time-locked to each pulse of the stimulation train. Similar entrainment was also observed in GPe efferents, a majority of which have been shown to project through GPi en route to the subthalamic nucleus. The models suggest that pallidal DBS may have broader network effects than previously realized and the modes of therapy may depend on the relative proportion of GPi and/or GPe efferents that are directly affected by the stimulation.
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Affiliation(s)
- Matthew D Johnson
- Department of Biomedical Engineering, Cleveland Clinic Foundation, 9500 Euclid Avenue, ND20, Cleveland, OH, 44195, USA
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17
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Gillies A, Willshaw D. Neuroinformatics and modeling of the basal ganglia: bridging pharmacology and physiology. Expert Rev Med Devices 2007; 4:663-72. [PMID: 17850200 DOI: 10.1586/17434440.4.5.663] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The subthalamic nucleus (STN) is the primary target for the chronic deep brain stimulation treatment of Parkinson's disease. STN neurons exhibit a variety of characteristic properties that may play a key role in the overall population response to deep brain stimulation. Neuroinformatics techniques, in particular computational modeling, provide a method of bringing together pharmacological phenomena, such as the loss of dopamine, with electrophysiological characteristics. Developing accurate models of STN neurons plays an important part in the process of uncovering the link between the changes in STN pharmacology, physiology and synaptic input that occurs with Parkinson's disease and the effectiveness of treatments targeting the STN. We review a general procedure for developing computational models and present a model of STN neurons that reveals important membrane channel interactions. In particular, changes in these channel interactions under parkinsonian conditions may underlie changes in characteristic physiology, critical in determining the mechanisms of deep brain stimulation.
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Affiliation(s)
- Andrew Gillies
- Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, Edinburgh EH1 2QL, UK.
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18
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Broicher T, Seidenbecher T, Meuth P, Munsch T, Meuth SG, Kanyshkova T, Pape HC, Budde T. T-current related effects of antiepileptic drugs and a Ca2+ channel antagonist on thalamic relay and local circuit interneurons in a rat model of absence epilepsy. Neuropharmacology 2007; 53:431-46. [PMID: 17675191 DOI: 10.1016/j.neuropharm.2007.05.030] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 05/29/2007] [Accepted: 05/30/2007] [Indexed: 11/19/2022]
Abstract
Channel blocking, anti-oscillatory, and anti-epileptic effects of clinically used anti-absence substances (ethosuximide, valproate) and the T-type Ca2+ current (IT) blocker mibefradil were tested by analyzing membrane currents in acutely isolated local circuit interneurons and thalamocortical relay (TC) neurons, slow intrathalamic oscillations in brain slices, and spike and wave discharges (SWDs) occurring in vivo in Wistar Albino Glaxo rats from Rijswijk (WAG/Rij). Substance effects in vitro were compared between WAG/Rij and a non-epileptic control strain, the ACI rats. Ethosuximide (ETX) and valproate were found to block IT in acutely isolated thalamic neurons. Block of IT by therapeutically relevant ETX concentrations (0.25-0.75 mM) was stronger in WAG/Rij, although the maximal effect at saturating concentrations (>or=10 mM) was stronger in ACI. Ethosuximide delayed the onset of the low threshold Ca2+ spike (LTS) of neurons recorded in slice preparations. Mibefradil (>or=2 microM) completely blocked IT and the LTS, dampened evoked thalamic oscillations, and attenuated SWDs in vivo. Computational modeling demonstrated that the complete effect of ETX can be replicated by a sole reduction of IT. However, the necessary degree of IT reduction was not induced by therapeutically relevant ETX concentrations. A combined reduction of IT, the persistent sodium current, and the Ca2+ activated K+ current resulted in an LTS alteration resembling the experimental observations. In summary, these results support the hypothesis of IT reduction as part of the mechanism of action of anti-absence drugs and demonstrate the ability of a specific IT antagonist to attenuate rhythmic burst firing and SWDs.
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Affiliation(s)
- Tilman Broicher
- Institut für Physiologie I, Westfälische Wilhelms-Universität Münster, Robert-Koch-Str. 27a, D-48149 Münster, Germany
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19
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Wykes RCE, Bauer CS, Khan SU, Weiss JL, Seward EP. Differential regulation of endogenous N- and P/Q-type Ca2+ channel inactivation by Ca2+/calmodulin impacts on their ability to support exocytosis in chromaffin cells. J Neurosci 2007; 27:5236-48. [PMID: 17494710 PMCID: PMC6672387 DOI: 10.1523/jneurosci.3545-06.2007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
P/Q-type (Ca(V)2.1) and N-type (Ca(V)2.2) Ca2+ channels are critical to stimulus-secretion coupling in the nervous system; feedback regulation of these channels by Ca2+ is therefore predicted to profoundly influence neurotransmission. Here we report divergent regulation of Ca2+-dependent inactivation (CDI) of native N- and P/Q-type Ca2+ channels by calmodulin (CaM) in adult chromaffin cells. Robust CDI of N-type channels was observed in response to prolonged step depolarizations, as well as repetitive stimulation with either brief step depolarizations or action potential-like voltage stimuli. Adenoviral expression of Ca2+-insensitive calmodulin mutants eliminated CDI of N-type channels. This is the first demonstration of CaM-dependent CDI of a native N-type channel. CDI of P/Q-type channels was by comparison modest and insensitive to expression of CaM mutants. Cloning of the C terminus of the Ca(V)2.1 alpha1 subunit from chromaffin cells revealed multiple splice variants lacking structural motifs required for CaM-dependent CDI. The physiological relevance of CDI on stimulus-coupled exocytosis was revealed by combining perforated-patch voltage-clamp recordings of pharmacologically isolated Ca2+ currents with membrane capacitance measurements of exocytosis. Increasing stimulus intensity to invoke CDI resulted in a significant decrease in the exocytotic efficiency of N-type channels compared with P/Q-type channels. Our results reveal unexpected diversity in CaM regulation of native Ca(V)2 channels and suggest that the ability of individual Ca2+ channel subtypes to undergo CDI may be tailored by alternative splicing to meet the specific requirements of a particular cellular function.
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Affiliation(s)
- Robert C. E. Wykes
- Department of Biomedical Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom
| | - Claudia S. Bauer
- Department of Biomedical Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom
| | - Saeed U. Khan
- Department of Biomedical Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom
| | - Jamie L. Weiss
- Department of Biomedical Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom
| | - Elizabeth P. Seward
- Department of Biomedical Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom
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20
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Hepp R, Tricoire L, Hu E, Gervasi N, Paupardin-Tritsch D, Lambolez B, Vincent P. Phosphodiesterase type 2 and the homeostasis of cyclic GMP in living thalamic neurons. J Neurochem 2007; 102:1875-1886. [PMID: 17561940 DOI: 10.1111/j.1471-4159.2007.04657.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ubiquitous second messenger cyclic GMP (cGMP) is synthesized by soluble guanylate cyclases in response to nitric oxide (NO) and degraded by phosphodiesterases (PDE). We studied the homeostasis of cGMP in living thalamic neurons by using the genetically encoded fluorescence resonance energy transfer sensor Cygnet, expressed in brain slices through viral gene transfer. Natriuretic peptides had no effect on cGMP. Basal cGMP levels decreased upon inhibition of NO synthases or soluble guanylate cyclases and increased when PDEs were inhibited. Single cell RT-PCR analysis showed that thalamic neurons express PDE1, PDE2, PDE9, and PDE10. Basal cGMP levels were increased by the PDE2 inhibitors erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) and BAY60-7550 but were unaffected by PDE1 or PDE10 inhibitors. We conclude that PDE2 regulates the basal cGMP concentration in thalamic neurons. In addition, in the presence of 3-isobutyl-1-methylxanthine (IBMX), cGMP still decreased after application of a NO donor. Probenecid, a blocker of cGMP transporters, had no effect on this decrease, leaving PDE9 as a possible candidate for decreasing cGMP concentration. Basal cGMP level is poised at an intermediate level from which it can be up or down-regulated according to the cyclase and PDE activities.
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Affiliation(s)
- R Hepp
- Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France
| | - L Tricoire
- Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France
| | - E Hu
- Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France
| | - N Gervasi
- Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France
| | | | - B Lambolez
- Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France
| | - P Vincent
- Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France
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21
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Gervasi N, Hepp R, Tricoire L, Zhang J, Lambolez B, Paupardin-Tritsch D, Vincent P. Dynamics of protein kinase A signaling at the membrane, in the cytosol, and in the nucleus of neurons in mouse brain slices. J Neurosci 2007; 27:2744-50. [PMID: 17360896 PMCID: PMC6672563 DOI: 10.1523/jneurosci.5352-06.2007] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The cAMP-dependent protein kinase A (PKA) plays a ubiquitous role in the regulation of neuronal activity, but the dynamics of its activation have been difficult to investigate. We used the genetically encoded fluorescent probe AKAR2 to record PKA activation in the cytosol and the nucleus of neurons in mouse brain slice preparations, whereas the potassium current underlying the slow afterhyperpolarization potential (sAHP) in thalamic intralaminar neurons was used to monitor PKA activation at the membrane. Adenylyl cyclase was stimulated either directly using forskolin or via activation of 5-HT7 receptors. Both stimulations produced a maximal effect on sAHP, whereas in the cytosol, the amplitude of the 5-HT7 receptor-mediated response was half of that after direct adenylyl cyclase stimulation with forskolin. 5-HT7-mediated PKA responses were obtained in 30 s at the membrane, in 2.5 min in the cytosol, and in 13 min in the nucleus. Our results show in morphologically intact mammalian neurons the potential physiological relevance of PKA signal integration at the subcellular level: neuromodulators produce fast and powerful effects on membrane excitability, consistent with a highly efficient functional coupling between adenylyl cyclases, PKA, and target channels. Phosphorylation in the cytosol is slower and of graded amplitude, showing a differential integration of the PKA signal between the membrane and the cytosol. The nucleus integrates these cytosolic signals over periods of tens of minutes, consistent with passive diffusion of the free catalytic subunit of PKA into the nucleus, eventually resulting in a graded modulation of gene expression.
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Affiliation(s)
- Nicolas Gervasi
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7102, and
- Université Pierre et Marie Curie-Paris 6, Unité Mixte de Recherche 7102, F-75005 Paris, France, and
| | - Régine Hepp
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7102, and
- Université Pierre et Marie Curie-Paris 6, Unité Mixte de Recherche 7102, F-75005 Paris, France, and
| | - Ludovic Tricoire
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7102, and
- Université Pierre et Marie Curie-Paris 6, Unité Mixte de Recherche 7102, F-75005 Paris, France, and
| | - Jin Zhang
- Departments of Pharmacology and Molecular Sciences and
- Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Bertrand Lambolez
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7102, and
- Université Pierre et Marie Curie-Paris 6, Unité Mixte de Recherche 7102, F-75005 Paris, France, and
| | - Danièle Paupardin-Tritsch
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7102, and
- Université Pierre et Marie Curie-Paris 6, Unité Mixte de Recherche 7102, F-75005 Paris, France, and
| | - Pierre Vincent
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7102, and
- Université Pierre et Marie Curie-Paris 6, Unité Mixte de Recherche 7102, F-75005 Paris, France, and
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22
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Tippens AL, Lee A. Caldendrin, a Neuron-specific Modulator of Cav/1.2 (L-type) Ca2+ Channels. J Biol Chem 2007; 282:8464-73. [PMID: 17224447 DOI: 10.1074/jbc.m611384200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
EF-hand Ca2+-binding proteins such as calmodulin and CaBP1 have emerged as important regulatory subunits of voltage-gated Ca2+ channels. Here, we show that caldendrin, a variant of CaBP1 enriched in the brain, interacts with and distinctly modulates Cav1.2 (L-type) voltage-gated Ca2+ channels relative to other Ca2+-binding proteins. Caldendrin binds to the C-terminal IQ-domain of the pore-forming alpha1-subunit of Cav1.2 (alpha(1)1.2) and competitively displaces calmodulin and CaBP1 from this site. Compared with CaBP1, caldendrin causes a more modest suppression of Ca2+-dependent inactivation of Cav1.2 through a different subset of molecular determinants. Caldendrin does not bind to the N-terminal domain of alpha11.2, a site that is critical for functional interactions of the channel with CaBP1. Deletion of the N-terminal domain inhibits CaBP1, but spares caldendrin modulation of Cav1.2 inactivation. In contrast, mutations of the IQ-domain abolish physical and functional interactions of caldendrin and Cav1.2, but do not prevent channel modulation by CaBP1. Using antibodies specific for caldendrin and Cav1.2, we show that caldendrin coimmunoprecipitates with Cav1.2 from the brain and colocalizes with Cav1.2 in somatodendritic puncta of cortical neurons in culture. Our findings reveal functional diversity within related Ca2+-binding proteins, which may enhance the specificity of Ca2+ signaling by Cav1.2 channels in different cellular contexts.
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Affiliation(s)
- Alyssa L Tippens
- Department of Pharmacology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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23
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Anelli R, Sanelli L, Bennett DJ, Heckman CJ. Expression of L-type calcium channel alpha(1)-1.2 and alpha(1)-1.3 subunits on rat sacral motoneurons following chronic spinal cord injury. Neuroscience 2007; 145:751-63. [PMID: 17291691 DOI: 10.1016/j.neuroscience.2006.12.043] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 12/10/2006] [Accepted: 12/11/2006] [Indexed: 12/22/2022]
Abstract
In the presence of the monoamines serotonin and norepinephrine, motoneurons readily generate large persistent inward currents (PICs). The resulting plateau potentials amplify and sustain motor output. Monoaminergic input to the cord originates in the brainstem and the sharp reduction in monoamine levels that occurs following acute spinal cord injury greatly decreases motoneuron excitability. However, recent studies in the adult sacral cord of the rat have shown that motoneurons reacquire the ability to generate PICs and plateau potentials within 1-2 months following spinal transection. Ca(v)1.3 L-type calcium channels are involved in generating PICs in both healthy and injured animals. Additionally, expression of Ca(v)1.2 and Ca(v)1.3 L-type calcium channels is altered in several pathological conditions. Therefore, in this paper we analyzed the expression of L-type calcium channel alpha(1) subunits within the motoneuron pool following a complete transection of the spinal cord at the level of the sacral vertebra (S)2 segment. The analysis was done both caudally (S4 segment) and rostrally [thoracic vertebra (T)6 segment] from the injury site. The S4 segment was significantly reduced in diameter when compared with control animals, and this reduction was more evident in the white matter. Ca(v)1.2 alpha(1) subunit expression significantly increased (26%) in the motoneuron pool located caudally but not rostrally from the injury site. In contrast, the expression of Ca(v)1.3 alpha(1) subunit remained unchanged in both S4 and T6 segments. The differential expression of the two alpha(1) subunits in spinal injury suggests that Ca(v)1.2 and Ca(v)1.3 channels have different functions in neuronal adaptation following spinal cord injury.
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Affiliation(s)
- R Anelli
- Department of Physiology, Northwestern University Feinberg School of Medicine, Morton 5-666, 303 East Chicago Avenue (M211), Chicago, IL 60611, USA.
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24
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Loane DJ, Hicks GA, Perrino BA, Marrion NV. Inhibition of BKCachannel activity by association with calcineurin in rat brain. Eur J Neurosci 2006; 24:433-41. [PMID: 16903851 DOI: 10.1111/j.1460-9568.2006.04931.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Large conductance calcium-activated potassium (BK(Ca)) channels are regulated by a number of different protein kinases and phosphatases. The close association of enzymes and channel have been shown to underlie many examples of modulation. However, only the association of protein kinase A with the BK(Ca) channel has been detailed [Tian et al. (2003)J. Biol. Chem., 278, 8669-8677]. We have found using reciprocal immunoprecipitations that the BK(Ca) channel associates with the calcium/calmodulin-dependent phosphatase calcineurin, in Wistar rat brain. A HA-tagged construct of the carboxyl terminus of rSlo(27), a variant of the BK(Ca) channel that is abundant in the hippocampus [Ha et al. (2000)Eur. J. Biochem., 267, 910-9218], was found to associate only with the B subunit of calcineurin. This data suggests that the majority of the interaction of the BK(Ca) channel with calcineurin is mediated by the B subunit of the phosphatase. This was confirmed by using glutathione-S-transferase (GST) fusion proteins of the linker regions between the S7-S10 hydrophobic domains in the carboxyl terminus of rSlo(27), where only the B subunit of calcineurin interacted with regions between S7 and S9 of the channel. Addition of a constitutively active calcineurin (CaN(420)) to inside-out membrane patches excised from cultured hippocampal neurons resulted in a dramatic reduction in BK(Ca) channel open probability, with only very short-duration events being apparent. These data suggest that BK(Ca) channel activity is inhibited by calcineurin, an effect mediated by the association of the calcineurin B subunit with the carboxyl terminus of the channel.
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Affiliation(s)
- David J Loane
- Department of Pharmacology and MRC Centre for Synaptic Plasticity, School of Medical Sciences, University of Bristol, Bristol, BS8 1TD, UK
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25
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Mukhamedyarov MA, Grishin SN, Zefirov AL, Palotás A. Evidences for calcium-dependent inactivation of calcium current at the frog motor nerve terminal. Brain Res Bull 2006; 69:652-5. [PMID: 16716833 DOI: 10.1016/j.brainresbull.2006.03.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2005] [Revised: 03/04/2006] [Accepted: 03/20/2006] [Indexed: 11/25/2022]
Abstract
Assessment of calcium-dependent inactivation of calcium current in nerve terminals is not feasible due to technical reasons. Perineural measurement of calcium-flow, however, might be utilized as indirect means to evaluate synaptic currents. Using perineural recording from frog neuromuscular junction, supra-threshold stimuli applied to motor nerve in paired-pulse manner with varying inter-pulse intervals (5-50 ms) are demonstrated in this study to cause paired-pulse depression (PPD) of Ca(2+)-current. PPD of Ca(2+)-flow was reduced at lower extracellular Ca(2+) concentrations, in BAPTA-AM and EGTA-AM treated preparations and after replacing extracellular Ca(2+) with Sr(2+). Using perineural measurement of calcium current as an indirect model to investigate synaptic ionic activity, our findings demonstrate that PPD may be attributed to calcium-dependent inactivation of Ca(2+)-current, which may serve as negative feedback in response to massive Ca(2+) entry to motor nerve terminals. A putative sensor of Ca(2+)-current is also proposed in this study.
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Affiliation(s)
- Marat A Mukhamedyarov
- Department of Physiology, Kazan State Medical University, ul. Butlerov 49, R-420012 Kazan, Russia
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26
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Gillies A, Willshaw D. Membrane Channel Interactions Underlying Rat Subthalamic Projection Neuron Rhythmic and Bursting Activity. J Neurophysiol 2006; 95:2352-65. [PMID: 16148272 DOI: 10.1152/jn.00525.2005] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A computational model of the rat subthalamic nucleus projection neuron is constructed using electrophysiological and morphological data and a restricted set of channel specifications. The model cell exhibits a wide range of electrophysiological behaviors characteristic of rat subthalamic neurons. It reveals that a key set of three channels play a primary role in distinguishing behaviors: a high-voltage-activated calcium channel (Cav1.2.-1.3), a low-voltage-activated calcium channel (Cav3.-), and a small current calcium-activated potassium channel (KCa2.1–2.3). Short and long posthyperpolarization rebound responses, low-frequency rhythmic bursting (<1 Hz), higher-frequency rhythmic bursting (4–7 Hz), and slow action and depolarizing potentials are behaviors all mediated by the interaction of these channels. This interaction can generate a robust calcium-dependent extended depolarization in the dendrites (a depolarizing plateau). The diversity observed in the rat subthalamic physiology (such as short or long rebounds, or the presence of low-frequency rhythmic busting) can arise from alterations in both the density and distributions of these channel types and, consequently, their ability to generate this depolarizing plateau. A number of important predictions arise from the model. For example, blocking or disrupting the low-voltage-activated Cav3.- calcium current should mute the emergence of rebound responses and rhythmic bursting. Conversely, increasing this channel current via large hyperpolarizing potentials in combination with partial blockade of the high-voltage-activated calcium channels should lead to the more experimentally elusive in vitro high-frequency bursting.
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Affiliation(s)
- Andrew Gillies
- Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, Edinburgh, United Kingdom.
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27
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28
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Meuth SG, Kanyshkova T, Landgraf P, Pape HC, Budde T. Influence of Ca2+-binding proteins and the cytoskeleton on Ca2+-dependent inactivation of high-voltage activated Ca2+ currents in thalamocortical relay neurons. Pflugers Arch 2005; 450:111-22. [PMID: 15647929 DOI: 10.1007/s00424-004-1377-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2004] [Revised: 11/03/2004] [Accepted: 12/13/2004] [Indexed: 11/24/2022]
Abstract
Ca2+-dependent inactivation (CDI) of high-voltage activated (HVA) Ca2+ channels was investigated in acutely isolated and identified thalamocortical relay neurons of the dorsal lateral geniculate nucleus (dLGN) by combining electrophysiological and immunological techniques. The influence of Ca2+-binding proteins, calmodulin and the cytoskeleton on CDI was monitored using double-pulse protocols (a constant post-pulse applied shortly after the end of conditioning pre-pulses of increasing magnitude). Under control conditions the degree of inactivation (34+/-9%) revealed a U-shaped and a sigmoid dependency of the post-pulse current amplitude on pre-pulse voltage and charge influx, respectively. In contrast to a high concentration (5.5 mM) of EGTA (31+/-3%), a low concentration (3 microM) of parvalbumin (20+/-2%) and calbindin(D28K) (24+/-4%) significantly reduced CDI. Subtype-specific Ca2+ channel blockers indicated that L-type, but not N-type Ca2+ channels are governed by CDI and modulated by Ca2+-binding proteins. These results point to the possibility that activity-dependent changes in the intracellular Ca2+-binding capacity can influence CDI substantially. Furthermore, calmodulin antagonists (phenoxybenzamine, 22+/-2%; calmodulin binding domain, 17+/-1%) and cytoskeleton stabilizers (taxol, 23+/-5%; phalloidin, 15+/-3%) reduced CDI. Taken together, these findings indicate the concurrent occurrence of different CDI mechanisms in a specific neuronal cell type, thereby supporting an integrated model of this feedback mechanism and adding further to the elucidation of the role of HVA Ca2+ channels in thalamic physiology.
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Affiliation(s)
- Sven G Meuth
- Otto-von-Guericke Universität, Medizinische Fakultät, Institut für Physiologie, Leipziger Strasse 44, 39120, Magdeburg, Germany.
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29
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Gonda K, Yoshida A, Oami K, Takahashi M. Centrin is essential for the activity of the ciliary reversal-coupled voltage-gated Ca2+ channels. Biochem Biophys Res Commun 2004; 323:891-7. [PMID: 15381084 DOI: 10.1016/j.bbrc.2004.08.172] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Indexed: 11/26/2022]
Abstract
Voltage-gated Ca(2+) channels play a critical role in controlling Ca(2+) entry in various cells. Ciliary reversal in Paramecium depends on the Ca(2+) influx through voltage-gated Ca(2+) channels on the ciliary membrane. One of the voltage-gated Ca(2+) channel mutants in Paramecium caudatum, cnrC, neither produces Ca(2+) action potentials nor responds to any depolarizing stimuli. Here, we report that the cnrC(+) gene product is P. caudatum centrin (Pccentrin1p), a member of the Ca(2+)-binding EF-hand protein superfamily. The Pccentrin1p gene of cnrC was found to contain a single-base deletion, a mutation that caused the loss of the fourth EF-hand of Pccentrin1p. Moreover, the wild-type Ca(2+) channel function was impaired by Pccentrin1p gene silencing, leading to the loss of current-evoked Ca(2+) action potentials and stimulated ciliary reversal. These results demonstrate that Pccentrin1p is indispensable for the activity of the voltage-gated Ca(2+) channels that control ciliary reversal in Paramecium.
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Affiliation(s)
- Kohsuke Gonda
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
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30
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Zhou H, Kim SA, Kirk EA, Tippens AL, Sun H, Haeseleer F, Lee A. Ca2+-binding protein-1 facilitates and forms a postsynaptic complex with Cav1.2 (L-type) Ca2+ channels. J Neurosci 2004; 24:4698-708. [PMID: 15140941 PMCID: PMC6729388 DOI: 10.1523/jneurosci.5523-03.2004] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ca2+-binding protein-1 (CaBP1) is a Ca2+-binding protein that is closely related to calmodulin (CaM) and localized in somatodendritic regions of principal neurons throughout the brain, but how CaBP1 participates in postsynaptic Ca2+ signaling is not known. Here, we describe a novel role for CaBP1 in the regulation of Ca2+ influx through Ca(v)1.2 (L-type) Ca2+ channels. CaBP1 interacts directly with the alpha1 subunit of Ca(v)1.2 at sites that also bind CaM. CaBP1 binding to one of these sites, the IQ domain, is Ca2+ dependent and competitive with CaM binding. The physiological significance of this interaction is supported by the association of Ca(v)1.2 and CaBP1 in postsynaptic density fractions purified from rat brain. Moreover, in double-label immunofluorescence experiments, CaBP1 and Ca(v)1.2 colocalize in numerous cell bodies and dendrites of neurons, particularly in pyramidal cells in the CA3 region of the hippocampus and in the dorsal cortex. In electrophysiological recordings of cells transfected with Ca(v)1.2, CaBP1 greatly prolonged Ca2+ currents, prevented Ca2+-dependent inactivation, and caused Ca2+-dependent facilitation of currents evoked by step depolarizations and repetitive stimuli. These effects contrast with those of CaM, which promoted strong Ca2+-dependent inactivation of Ca(v)1.2 with these same voltage protocols. Our findings reveal how Ca2+-binding proteins, such as CaM and CaBP1, differentially adjust Ca2+ influx through Ca(v)1.2 channels, which may specify diverse modes of Ca2+ signaling in neurons.
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Affiliation(s)
- Hong Zhou
- Department of Pharmacology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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31
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El-Banoua F, Caraballo I, Flores JA, Galan-Rodriguez B, Fernandez-Espejo E. Effects on turning of microinjections into basal ganglia of D1 and D2 dopamine receptors agonists and the cannabinoid CB1 antagonist SR141716A in a rat Parkinson's model. Neurobiol Dis 2004; 16:377-85. [PMID: 15193294 DOI: 10.1016/j.nbd.2004.03.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2003] [Revised: 02/27/2004] [Accepted: 03/05/2004] [Indexed: 11/22/2022] Open
Abstract
Brain cannabinoid CB(1) receptors are expressed in neural areas that contribute to movement such as basal ganglia, where they co-localize with dopamine D(1) and D(2) receptors. The objective of the present study was to further study the functional role of CB(1) receptors along with D(1) and D(2) dopamine receptors of basal ganglia by local injections of SR141716A (CB(1) receptor antagonist), SKF-38393 (D(1) agonist), and quinpirole (D(2) agonist), in a rat Parkinson's model. Turning response after amphetamine was considered as the parkinsonian variable for quantifying motor effects of drugs. The findings indicated that, after intrastriatal infusions, both D(1) or D(2) dopamine receptor agonists alone reduced turning in parkinsonian rats. At the pallidal and subthalamic levels, D(1) (not D(2)) receptor stimulation also reduced rotation. Regarding SR141716A-induced effects, CB(1) antagonism reduced motor asymmetry in parkinsonian rats after injections into striatum, globus pallidus, and to a lesser extent, subthalamic nucleus. At the level of dorsal striatum, effects of SR141716A were mediated through an opposite modulation of D(1) and D(2) dopamine receptor function. At the pallidal and subthalamic nucleus levels, motor effects after SR14716A are not associated to modulation of D(1) and D(2) receptor function.
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MESH Headings
- Animals
- Disease Models, Animal
- Globus Pallidus/drug effects
- Male
- Microinjections
- Motor Activity/drug effects
- Neostriatum/drug effects
- Parkinsonian Disorders/drug therapy
- Piperidines/pharmacology
- Pyrazoles/pharmacology
- Rats
- Rats, Wistar
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/metabolism
- Receptors, Dopamine D1/agonists
- Receptors, Dopamine D1/metabolism
- Receptors, Dopamine D2/agonists
- Receptors, Dopamine D2/metabolism
- Rimonabant
- Subthalamic Nucleus/drug effects
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Affiliation(s)
- Fadwa El-Banoua
- Departamento de Fisiologia Medica y Biofisica, Universidad de Sevilla, E-41009 Seville, Spain
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32
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Pape HC, Munsch T, Budde T. Novel vistas of calcium-mediated signalling in the thalamus. Pflugers Arch 2004; 448:131-8. [PMID: 14770314 DOI: 10.1007/s00424-003-1234-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2003] [Accepted: 12/12/2003] [Indexed: 11/29/2022]
Abstract
Traditionally, the role of calcium ions (Ca(2+)) in thalamic neurons has been viewed as that of electrical charge carriers. Recent experimental findings in thalamic cells have only begun to unravel a highly complex Ca(2+) signalling network that exploits extra- and intracellular Ca(2+) sources. In thalamocortical relay neurons, interactions between T-type Ca(2+) channel activation, Ca(2+)-dependent regulation of adenylyl cyclase activity and the hyperpolarization-activated cation current ( I(h)) regulate oscillatory burst firing during periods of sleep and generalized epilepsy, while a functional triad between Ca(2+) influx through high-voltage-activated (most likely L-type) Ca(2+) channels, Ca(2+)-induced Ca(2+) release via ryanodine receptors (RyRs) and a repolarizing mechanism (possibly via K(+) channels of the BK(Ca) type) supports tonic spike firing as required during wakefulness. The mechanisms seem to be located mostly at dendritic and somatic sites, respectively. One functional compartment involving local GABAergic interneurons in certain thalamic relay nuclei is the glomerulus, in which the dendritic release of GABA is regulated by Ca(2+) influx via canonical transient receptor potential channels (TRPC), thereby presumably enabling transmitters of extrathalamic input systems that are coupled to phospholipase C (PLC)-activating receptors to control feed-forward inhibition in the thalamus. Functional interplay between T-type Ca(2+) channels in dendrites and the A-type K(+) current controls burst firing, contributing to the range of oscillatory activity observed in these interneurons. GABAergic neurons in the reticular thalamic (RT) nucleus recruit a specific set of Ca(2+)-dependent mechanisms for the generation of rhythmic burst firing, of which a particular T-type Ca(2+) channel in the dendritic membrane, the Ca(2+)-dependent activation of non-specific cation channels ( I(CAN)) and of K(+) channels (SK(Ca) type) are key players. Glial Ca(2+) signalling in the thalamus appears to be a basic mechanism of the dynamic and integrated exchange of information between glial cells and neurons. The conclusion from these observations is that a localized calcium signalling network exists in all neuronal and probably also glial cell types in the thalamus and that this network is dedicated to the precise regulation of the functional mode of the thalamus during various behavioural states.
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Affiliation(s)
- Hans-Christian Pape
- Institut für Physiologie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Leipziger Strasse 44, 39120, Magdeburg, Germany.
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33
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Abstract
The molecular mechanisms of learning and memory, and the underlying bidirectional changes in synaptic plasticity that sustain them largely implicate protein kinases and phosphatases. Specifically, Ca(2+)-dependent kinases and phosphatases actively control neuronal processing by forming a tightly regulated balance in which they oppose each other. In this balance, calcineurin (PP2B) is a critical protein phosphatase whose main function is to negatively modulate learning, memory, and plasticity. It acts by dephosphorylating numerous substrates in different neuronal compartments. This review outlines some of CN neuronal targets and their implication in synaptic functions, and describes the role of CN in the acquisition, storage, retrieval, and extinction of memory, as well as in bidirectional plasticity.
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Affiliation(s)
- Isabelle M Mansuy
- Department of Biology, Swiss Federal Institute of Technology, ETH Hönggerberg HPM D24, CH-8093, Zurich, Switzerland
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34
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Liang H, DeMaria CD, Erickson MG, Mori MX, Alseikhan BA, Yue DT. Unified mechanisms of Ca2+ regulation across the Ca2+ channel family. Neuron 2003; 39:951-60. [PMID: 12971895 DOI: 10.1016/s0896-6273(03)00560-9] [Citation(s) in RCA: 249] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
L-type (CaV1.2) and P/Q-type (CaV2.1) calcium channels possess lobe-specific CaM regulation, where Ca2+ binding to one or the other lobe of CaM triggers regulation, even with inverted polarity of modulation between channels. Other major members of the CaV1-2 channel family, R-type (CaV2.3) and N-type (CaV2.2), have appeared to lack such CaM regulation. We report here that R- and N-type channels undergo Ca(2+)-dependent inactivation, which is mediated by the CaM N-terminal lobe and present only with mild Ca2+ buffering (0.5 mM EGTA) characteristic of many neurons. These features, together with the CaM regulatory profiles of L- and P/Q-type channels, are consistent with a simplifying principle for CaM signal detection in CaV1-2 channels-independent of channel context, the N- and C-terminal lobes of CaM appear invariably specialized for decoding local versus global Ca2+ activity, respectively.
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MESH Headings
- Amino Acid Sequence
- Animals
- Calcium/metabolism
- Calcium Channels/chemistry
- Calcium Channels/genetics
- Calcium Channels/metabolism
- Calcium Channels, L-Type/chemistry
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Channels, N-Type/chemistry
- Calcium Channels, N-Type/genetics
- Calcium Channels, N-Type/metabolism
- Calcium Channels, P-Type/chemistry
- Calcium Channels, P-Type/genetics
- Calcium Channels, P-Type/metabolism
- Calcium Channels, Q-Type/chemistry
- Calcium Channels, Q-Type/genetics
- Calcium Channels, Q-Type/metabolism
- Calcium Channels, R-Type/chemistry
- Calcium Channels, R-Type/genetics
- Calcium Channels, R-Type/metabolism
- Calmodulin/metabolism
- Cattle
- Cell Line
- Dose-Response Relationship, Drug
- Humans
- Molecular Sequence Data
- Rats
- Sequence Homology, Amino Acid
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Affiliation(s)
- Haoya Liang
- Ca2+ Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205, USA
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35
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Contribution of TWIK-related acid-sensitive K+ channel 1 (TASK1) and TASK3 channels to the control of activity modes in thalamocortical neurons. J Neurosci 2003. [PMID: 12878686 DOI: 10.1523/jneurosci.23-16-06460.2003] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The thalamocortical network is characterized by rhythmic burst activity during natural sleep and tonic single-spike activity during wakefulness. The change between these two activity modes is partially governed by transmitters acting on leak K+ currents in the thalamus, although the nature of the constituting ion channels is not yet known. In the present study, the contribution of members of the two-pore domain K+ channel family to the leak current was investigated using whole-cell patch-clamp techniques and molecular biological techniques. RT-PCR and in situ hybridization revealed the expression of TWIK-related acid-sensitive K+ channel 1 (TASK 1) and TASK3 channels in the rat dLGN. Voltage-clamp recordings of thalamocortical relay neurons in slice preparations demonstrated the existence of a current component sensitive to the TASK channel blocker bupivacaine, which reversed at the presumed K+ equilibrium potential, showed outward rectification, and contributed approximately 40% to the standing outward current at depolarized values of the membrane potential (-28 mV). The pharmacological profile was indicative of TASK channels, in that the current was sensitive to changes in extracellular pH, reduced by muscarine and increased by halothane, and these effects were occluded by a near-maximal action of bupivacaine. Pharmacological manipulation of this current under current-clamp conditions resulted in a shift between burst and tonic firing modes. It is concluded that TASK1 and TASK3 channels contribute to the muscarine- and halothane-sensitive conductance in thalamocortical relay neurons, thereby contributing to the change in the activity mode of thalamocortical networks observed during the sleep-wake cycle and on application of inhalational anesthetics.
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36
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Budde T, Meuth S, Pape HC. Calcium-dependent inactivation of neuronal calcium channels. Nat Rev Neurosci 2002; 3:873-83. [PMID: 12415295 DOI: 10.1038/nrn959] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Thomas Budde
- Otto-von-Guericke-Universität, Institute of Physiology, Leipziger Strabetae 44, D-39120 Magdeburg, Germany.
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