51
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Minor DL, Findeisen F. Progress in the structural understanding of voltage-gated calcium channel (CaV) function and modulation. Channels (Austin) 2011; 4:459-74. [PMID: 21139419 DOI: 10.4161/chan.4.6.12867] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Voltage-gated calcium channels (CaVs) are large, transmembrane multiprotein complexes that couple membrane depolarization to cellular calcium entry. These channels are central to cardiac action potential propagation, neurotransmitter and hormone release, muscle contraction, and calcium-dependent gene transcription. Over the past six years, the advent of high-resolution structural studies of CaV components from different isoforms and CaV modulators has begun to reveal the architecture that underlies the exceptionally rich feedback modulation that controls CaV action. These descriptions of CaV molecular anatomy have provided new, structure-based insights into the mechanisms by which particular channel elements affect voltage-dependent inactivation (VDI), calcium‑dependent inactivation (CDI), and calcium‑dependent facilitation (CDF). The initial successes have been achieved through structural studies of soluble channel domains and modulator proteins and have proven most powerful when paired with biochemical and functional studies that validate ideas inspired by the structures. Here, we review the progress in this growing area and highlight some key open challenges for future efforts.
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Affiliation(s)
- Daniel L Minor
- Cardiovascular Research Institute, University of California-San Francisco, CA, USA.
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52
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Ronkainen JJ, Hänninen SL, Korhonen T, Koivumäki JT, Skoumal R, Rautio S, Ronkainen VP, Tavi P. Ca2+-calmodulin-dependent protein kinase II represses cardiac transcription of the L-type calcium channel alpha(1C)-subunit gene (Cacna1c) by DREAM translocation. J Physiol 2011; 589:2669-86. [PMID: 21486818 DOI: 10.1113/jphysiol.2010.201400] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Recent studies have demonstrated that changes in the activity of calcium-calmodulin-dependent protein kinase II (CaMKII) induce a unique cardiomyocyte phenotype through the regulation of specific genes involved in excitation-contraction (E-C)-coupling. To explain the transcriptional effects of CaMKII we identified a novel CaMKII-dependent pathway for controlling the expression of the pore-forming α-subunit (Cav1.2) of the L-type calcium channel (LTCC) in cardiac myocytes. We show that overexpression of either cytosolic (δC) or nuclear (δB) CaMKII isoforms selectively downregulate the expression of the Cav1.2. Pharmacological inhibition of CaMKII activity induced measurable changes in LTCC current density and subsequent changes in cardiomyocyte calcium signalling in less than 24 h. The effect of CaMKII on the α1C-subunit gene (Cacna1c) promoter was abolished by deletion of the downstream regulatory element (DRE), which binds transcriptional repressor DREAM/calsenilin/KChIP3. Imaging DREAM-GFP (green fluorescent protein)-expressing cardiomyocytes showed that CaMKII potentiates the calcium-induced nuclear translocation of DREAM. Thereby CaMKII increases DREAM binding to the DRE consensus sequence of the endogenous Cacna1c gene. By mathematical modelling we demonstrate that the LTCC downregulation through the Ca2+-CaMKII-DREAM cascade constitutes a physiological feedback mechanism enabling cardiomyocytes to adjust the calcium intrusion through LTCCs to the amount of intracellular calcium detected by CaMKII.
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Affiliation(s)
- Jarkko J Ronkainen
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, Neulaniementie 2, FI-70211 Kuopio, Finland
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53
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Shibasaki M, Kurokawa K, Mizuno K, Ohkuma S. Up-regulation of Cav1.2 subunit via facilitating trafficking induced by Vps34 on morphine-induced place preference in mice. Eur J Pharmacol 2011; 651:137-45. [DOI: 10.1016/j.ejphar.2010.11.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 11/09/2010] [Accepted: 11/12/2010] [Indexed: 10/18/2022]
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54
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Li Q, Sarna SK. Chronic stress targets posttranscriptional mechanisms to rapidly upregulate α1C-subunit of Cav1.2b calcium channels in colonic smooth muscle cells. Am J Physiol Gastrointest Liver Physiol 2011; 300:G154-63. [PMID: 21051529 PMCID: PMC3025508 DOI: 10.1152/ajpgi.00393.2010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Chronic stress elevates plasma norepinephrine, which enhances expression of the α(1C)-subunit of Ca(v)1.2b channels in colonic smooth muscle cells within 1 h. Transcriptional upregulation usually does not explain such rapid protein synthesis. We investigated whether chronic stress-induced release of norepinephrine utilizes posttranscriptional mechanisms to enhance the α(1C)-subunit. We performed experiments on colonic circular smooth muscle strips and in conscious rats, using a 9-day chronic intermittent stress protocol. Incubation of rat colonic muscularis externa with norepinephrine enhanced α(1C)-protein expression within 45 min, without a concomitant increase in α(1C) mRNA, indicating posttranscriptional regulation of α(1C)-protein by norepinephrine. We found that norepinephrine activates the PI3K/Akt/GSK-3β pathway to concurrently enhance α(1C)-protein translation and block its polyubiquitination and proteasomal degradation. Incubation of colonic muscularis externa with norepinephrine or LiCl, which inhibits GSK-3β, enhanced p-GSK-3β and α(1C)-protein time dependently. Using enrichment of phosphoproteins and ubiquitinated proteins, we found that both norepinephrine and LiCl decrease α(1C) phosphorylation and polyubiquitination. Concurrently, they suppress eIF2α (Ser51) phosphorylation and 4E-BP1 expression, which stimulates gene-specific translation. The antagonism of two upstream kinases, PI3K and Akt, inhibits the induction of α(1C)-protein by norepinephrine. Cyanopindolol (β(3)-AR-antagonist) almost completely suppresses and propranolol (β(1/2)-AR antagonist) partially suppresses norepinephrine-induced α(1C)-protein expression, whereas phentolamine and prazosin (α-AR and α(1)-AR antagonist, respectively) have no significant effect. Experiments in conscious animals showed that chronic stress activates the PI3K/Akt/GSK-3β signaling. We conclude that norepinephrine released by chronic stress rapidly enhances the protein expression of α(1C)-subunit of Ca(v)1.2b channels by concurrently suppressing its degradation and enhancing translation of existing transcripts to maintain homeostasis.
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Affiliation(s)
| | - Sushil K. Sarna
- 1Department of Internal Medicine and ,2Department of Neuroscience and Cell Biology, The University of Texas Medical Branch at Galveston, Galveston, Texas
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55
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Abstract
Calcium regulates a wide spectrum of physiological processes such as heartbeat, muscle contraction, neuronal communication, hormone release, cell division, and gene transcription. Major entryways for Ca(2+) in excitable cells are high-voltage activated (HVA) Ca(2+) channels. These are plasma membrane proteins composed of several subunits, including α(1), α(2)δ, β, and γ. Although the principal α(1) subunit (Ca(v)α(1)) contains the channel pore, gating machinery and most drug binding sites, the cytosolic auxiliary β subunit (Ca(v)β) plays an essential role in regulating the surface expression and gating properties of HVA Ca(2+) channels. Ca(v)β is also crucial for the modulation of HVA Ca(2+) channels by G proteins, kinases, and the Ras-related RGK GTPases. New proteins have emerged in recent years that modulate HVA Ca(2+) channels by binding to Ca(v)β. There are also indications that Ca(v)β may carry out Ca(2+) channel-independent functions, including directly regulating gene transcription. All four subtypes of Ca(v)β, encoded by different genes, have a modular organization, consisting of three variable regions, a conserved guanylate kinase (GK) domain, and a conserved Src-homology 3 (SH3) domain, placing them into the membrane-associated guanylate kinase (MAGUK) protein family. Crystal structures of Ca(v)βs reveal how they interact with Ca(v)α(1), open new research avenues, and prompt new inquiries. In this article, we review the structure and various biological functions of Ca(v)β, with both a historical perspective as well as an emphasis on recent advances.
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Affiliation(s)
- Zafir Buraei
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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56
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Beta-adrenergic-regulated phosphorylation of the skeletal muscle Ca(V)1.1 channel in the fight-or-flight response. Proc Natl Acad Sci U S A 2010; 107:18712-7. [PMID: 20937870 DOI: 10.1073/pnas.1012384107] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ca(V)1 channels initiate excitation-contraction coupling in skeletal and cardiac muscle. During the fight-or-flight response, epinephrine released by the adrenal medulla and norepinephrine released from sympathetic nerves increase muscle contractility by activation of the β-adrenergic receptor/cAMP-dependent protein kinase pathway and up-regulation of Ca(V)1 channels in skeletal and cardiac muscle. Although the physiological mechanism of this pathway is well defined, the molecular mechanism and the sites of protein phosphorylation required for Ca(V)1 channel regulation are unknown. To identify the regulatory sites of phosphorylation under physiologically relevant conditions, Ca(V)1.1 channels were purified from skeletal muscle and sites of phosphorylation on the α1 subunit were identified by mass spectrometry. Two phosphorylation sites were identified in the proximal C-terminal domain, serine 1575 (S1575) and threonine 1579 (T1579), which are conserved in cardiac Ca(V)1.2 channels (S1700 and T1704, respectively). In vitro phosphorylation revealed that Ca(V)1.1-S1575 is a substrate for both cAMP-dependent protein kinase and calcium/calmodulin-dependent protein kinase II, whereas Ca(V)1.1-T1579 is a substrate for casein kinase 2. Treatment of rabbits with isoproterenol to activate β-adrenergic receptors increased phosphorylation of S1575 in skeletal muscle Ca(V)1.1 channels in vivo, and treatment with propranolol to inhibit β-adrenergic receptors reduced phosphorylation. As S1575 and T1579 in Ca(V)1.1 channels and their homologs in Ca(V)1.2 channels are located at a key regulatory interface between the distal and proximal C-terminal domains, it is likely that phosphorylation of these sites in skeletal and cardiac muscle is directly involved in calcium channel regulation in response to the sympathetic nervous system in the fight-or-flight response.
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57
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Sun AY, Pitt GS. Pinning down the CaMKII targets in the L-type Ca(2+) channel: an essential step in defining CaMKII regulation. Heart Rhythm 2010; 8:631-3. [PMID: 20933100 DOI: 10.1016/j.hrthm.2010.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Indexed: 02/02/2023]
Affiliation(s)
- Albert Y Sun
- Ion Channel Research Unit, Division of Cardiovascular Diseases, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
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58
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Shibasaki M, Kurokawa K, Ohkuma S. Upregulation of L-type Ca(v)1 channels in the development of psychological dependence. Synapse 2010; 64:440-4. [PMID: 20169575 DOI: 10.1002/syn.20745] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Although L-type voltage-dependent Ca2+ channels regulate activity-dependent processes including synaptic plasticity and synapse formation, there are few data on the changes of Ca(v)1 channel expression in psychological dependence. This study investigated the role of L-type Ca(v)1 channel expression in the brain of mouse that was psychologically dependent on methamphetamine (2 mg/kg, subcutaneous injection [s.c.]), cocaine (10 mg/kg, s.c.), and morphine (5 mg/kg, s.c.) with the conditioned place preference paradigm. Intracerebroventricular administration of nifedipine (3, 10, and 30 nmol/mouse) dose-dependently reduced the development of methamphetamine-, cocaine-, and morphine-induced rewarding effect. Under such conditions, protein levels of both Ca(v)1.2 and Ca(v)1.3 in the frontal cortex and the limbic forebrain were significantly increased on methamphetamine-, cocaine-, and morphine-induced psychologically dependent mice. These findings suggest that the upregulation of Ca(v)1.2 and Ca(v)1.3 participated in the development of psychological dependence.
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Affiliation(s)
- Masahiro Shibasaki
- Department of Pharmacology, Kawasaki Medical School, Kurashiki 701-0192, Japan
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59
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Facilitation of murine cardiac L-type Ca(v)1.2 channel is modulated by calmodulin kinase II-dependent phosphorylation of S1512 and S1570. Proc Natl Acad Sci U S A 2010; 107:10285-9. [PMID: 20479240 DOI: 10.1073/pnas.0914287107] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Activity-dependent means of altering calcium (Ca(2)(+)) influx are assumed to be of great physiological consequence, although definitive tests of this assumption have only begun to emerge. Facilitation and inactivation offer two opposing, activity-dependent means of altering Ca(2+) influx via cardiac Ca(v)1.2 calcium channels. Voltage- and frequency-dependent facilitation of Ca(v)1.2 has been reported to depend on Calmodulin (CaM) and/or the activity of Calmodulin kinase II (CaMKII). Several sites within the cardiac L-type calcium channel complex have been proposed as the targets of CaMKII. Here, we generated mice with knockin mutations of alpha(1)1.2 S1512 and S1570 phosphorylation sites [sine facilitation (SF) mice]. Homocygote SF mice were viable and reproduced in a Mendelian ratio. Voltage-dependent facilitation in ventricular cardiomyocytes carrying the SF mutation was decreased from 1.58- to 1.18-fold. The CaMKII inhibitor KN-93 reduced facilitation to 1.28 in control cardiomyocytes. SF mutation negatively shifted the voltage-dependent inactivation and slowed recovery from inactivation, thereby making fewer channels available for activation. Telemetric ECG recordings at different heart rates showed that QT time decreased significantly more in SF than in control mice at higher rates. Our results strongly support the notion that CaMKII-dependent phosphorylation of Cav1.2 at S1512 and S1570 mediates Ca(2+) current facilitation in the murine heart.
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60
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Ca2+-dependent facilitation of Cav1.3 Ca2+ channels by densin and Ca2+/calmodulin-dependent protein kinase II. J Neurosci 2010; 30:5125-35. [PMID: 20392935 DOI: 10.1523/jneurosci.4367-09.2010] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ca(v)1 (L-type) channels and calmodulin-dependent protein kinase II (CaMKII) are key regulators of Ca(2+) signaling in neurons. CaMKII directly potentiates the activity of Ca(v)1.2 and Ca(v)1.3 channels, but the underlying molecular mechanisms are incompletely understood. Here, we report that the CaMKII-associated protein densin is required for Ca(2+)-dependent facilitation of Ca(v)1.3 channels. While neither CaMKII nor densin independently affects Ca(v)1.3 properties in transfected HEK293T cells, the two together augment Ca(v)1.3 Ca(2+) currents during repetitive, but not sustained, depolarizing stimuli. Facilitation requires Ca(2+), CaMKII activation, and its association with densin, as well as densin binding to the Ca(v)1.3 alpha(1) subunit C-terminal domain. Ca(v)1.3 channels and densin are targeted to dendritic spines in neurons and form a complex with CaMKII in the brain. Our results demonstrate a novel mechanism for Ca(2+)-dependent facilitation that may intensify postsynaptic Ca(2+) signals during high-frequency stimulation.
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61
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CaV1.2 beta-subunit coordinates CaMKII-triggered cardiomyocyte death and afterdepolarizations. Proc Natl Acad Sci U S A 2010; 107:4996-5000. [PMID: 20194790 DOI: 10.1073/pnas.0913760107] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Excessive activation of calmodulin kinase II (CaMKII) causes arrhythmias and heart failure, but the cellular mechanisms for CaMKII-targeted proteins causing disordered cell membrane excitability and myocardial dysfunction remain uncertain. Failing human cardiomyocytes exhibit increased CaMKII and voltage-gated Ca(2+) channel (Ca(V)1.2) activity, and enhanced expression of a specific Ca(V)1.2 beta-subunit protein isoform (beta(2a)). We recently identified Ca(V)1.2 beta(2a) residues critical for CaMKII phosphorylation (Thr 498) and binding (Leu 493), suggesting the hypothesis that these amino acids are crucial for cardiomyopathic consequences of CaMKII signaling. Here we show WT beta(2a) expression causes cellular Ca(2+) overload, arrhythmia-triggering cell membrane potential oscillations called early afterdepolarizations (EADs), and premature death in paced adult rabbit ventricular myocytes. Prevention of intracellular Ca(2+) release by ryanodine or global cellular CaMKII inhibition reduced EADs and improved cell survival to control levels in WT beta(2a)-expressing ventricular myocytes. In contrast, expression of beta(2a) T498A or L493A mutants mimicked the protective effects of ryanodine or global cellular CaMKII inhibition by reducing Ca(2+) entry through Ca(V)1.2 and inhibiting EADs. Furthermore, Ca(V)1.2 currents recorded from cells overexpressing CaMKII phosphorylation- or binding-incompetent beta(2a) subunits were incapable of entering a CaMKII-dependent high-activity gating mode (mode 2), indicating that beta(2a) Thr 498 and Leu 493 are required for Ca(V)1.2 activation by CaMKII in native cells. These data show that CaMKII binding and phosphorylation sites on beta(2a) are concise but pivotal components of a molecular and biophysical and mechanism for EADs and impaired survival in adult cardiomyocytes.
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62
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Hao LY, Wang WY, Minobe E, Han DY, Xu JJ, Kameyama A, Kameyama M. The distinct roles of calmodulin and calmodulin kinase II in the reversal of run-down of L-type Ca(2+) channels in guinea-pig ventricular myocytes. J Pharmacol Sci 2010; 111:416-25. [PMID: 20019447 DOI: 10.1254/jphs.09094fp] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
In this study, we investigated the roles of calmodulin kinase II (CaMKII) and calmodulin (CaM) in the reversal of run-down of L-type Ca(2+) channels. Single Ca(2+)-channel activities in guinea-pig ventricular myocytes were recorded using the patch-clamp technique, and run-down of the channel activities was induced by inside-out patch formation in the basic internal solution. At 1 min after patch excision, 1 - 30 muM CaMKII mutant T286D (CaMKIIT286D), a constitutively active type of CaMKII, induced the Ca(2+)-channel activities to only 2% - 10% of that recorded in the cell-attached mode. However, in the presence of CaMKIIT286D, the time-dependent attenuation of CaM's effects in the reversal of run-down was abolished. A GST-fusion protein containing amino acids 1509 - 1789 of the C-terminal region of guinea-pig Cav1.2 (CT1) was prepared. In pull-down assays, CT1 treated with CaMKIIT286D showed a higher affinity for CaM compared with CT1 treated with phosphatase. We propose a model in which CaMKII-mediated phosphorylation of the channels regulates the binding of CaM to the channels in the reversal of run-down of L-type Ca(2+) channels.
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Affiliation(s)
- Li-Ying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacological Sciences, China Medical University, Shenyang 110001, China.
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63
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Lavialle-Defaix C, Moignot B, Legros C, Lapied B. How Does Calcium-Dependent Intracellular Regulation of Voltage-Dependent Sodium Current Increase the Sensitivity to the Oxadiazine Insecticide Indoxacarb Metabolite Decarbomethoxylated JW062 (DCJW) in Insect Pacemaker Neurons? J Pharmacol Exp Ther 2010; 333:264-72. [DOI: 10.1124/jpet.109.163519] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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64
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Both N- and C-lobes of calmodulin are required for Ca2+-dependent regulations of CaV1.2 Ca2+ channels. Biochem Biophys Res Commun 2010; 391:1170-6. [DOI: 10.1016/j.bbrc.2009.11.171] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 11/28/2009] [Indexed: 11/24/2022]
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65
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Dingemans MML, van den Berg M, Bergman A, Westerink RHS. Calcium-related processes involved in the inhibition of depolarization-evoked calcium increase by hydroxylated PBDEs in PC12 cells. Toxicol Sci 2009; 114:302-9. [PMID: 20044592 DOI: 10.1093/toxsci/kfp310] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In vitro studies indicated that hydroxylated polybrominated diphenyl ethers (OH-PBDEs) have an increased toxic potential compared to their parent congeners. An example is the OH-PBDE-induced increase of basal intracellular Ca(2+) concentration ([Ca(2+)](i)) by release of Ca(2+) from endoplasmic reticulum (ER) and mitochondria and/or influx of extracellular Ca(2+). ER and mitochondria regulate Ca(2+) homeostasis in close association with voltage-gated Ca(2+) channels (VGCCs). Therefore, effects of (OH-)PBDEs on the depolarization-evoked (100 mM K(+)) net increase in [Ca(2+)](i) (depolarization-evoked [Ca(2+)](i)) were measured in neuroendocrine pheochromocytoma cells using the Ca(2+)-responsive dye Fura-2. OH-PBDEs dose dependently inhibited depolarization-evoked [Ca(2+)](i). This inhibition was potentiated by a preceding increase in basal [Ca(2+)](i). Especially at higher concentrations of OH-PBDEs (5-20 microM), large increases in basal [Ca(2+)](i) strongly inhibited depolarization-evoked [Ca(2+)](i). The inhibition appeared more sensitive to increases in basal [Ca(2+)](i) by Ca(2+) release from intracellular stores (by 3-OH-BDE-47 or 6'-OH-BDE-49) compared to those by influx of extracellular Ca(2+) (by 6-OH-BDE-47 or 5-OH-BDE-47). The expected [Ca(2+)](i) difference close to the membrane suggests involvement of Ca(2+)-dependent regulatory processes close to VGCCs. When coapplied with depolarization, some OH-PBDEs induced also moderate direct inhibition of depolarization-evoked [Ca(2+)](i). Polybrominated diphenyl ethers and methoxylated BDE-47 affected neither basal nor depolarization-evoked [Ca(2+)](i), except for BDE-47, which moderately increased fluctuations in basal [Ca(2+)](i) and depolarization-evoked [Ca(2+)](i). These findings demonstrate that OH-PBDEs inhibit depolarization-evoked [Ca(2+)](i) depending on preceding basal [Ca(2+)](i). Related environmental pollutants that affect Ca(2+) homeostasis (e.g., polychlorinated biphenyls) may thus also inhibit depolarization-evoked [Ca(2+)](i), justifying further investigation of possible mixture effects of environmental pollutants on Ca(2+) homeostasis.
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Affiliation(s)
- Milou M L Dingemans
- Neurotoxicology Research Group, Toxicology Division, Institute for Risk Assessment Sciences, Utrecht University, NL-3508 TD Utrecht, The Netherlands.
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66
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Song YH, Cho H, Ryu SY, Yoon JY, Park SH, Noh CI, Lee SH, Ho WK. L-type Ca(2+) channel facilitation mediated by H(2)O(2)-induced activation of CaMKII in rat ventricular myocytes. J Mol Cell Cardiol 2009; 48:773-80. [PMID: 19883656 DOI: 10.1016/j.yjmcc.2009.10.020] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 10/17/2009] [Accepted: 10/26/2009] [Indexed: 10/20/2022]
Abstract
The Ca(2+)-dependent facilitation (CDF) of L-type Ca(2+) channels, a major mechanism for force-frequency relationship of cardiac contraction, is mediated by Ca(2+)/CaM-dependent kinase II (CaMKII). Recently, CaMKII was shown to be activated by methionine oxidation. We investigated whether oxidation-dependent CaMKII activation is involved in the regulation of L-type Ca(2+) currents (I(Ca,L)) by H(2)O(2) and whether Ca(2+) is required in this process. Using patch clamp, I(Ca)(,L) was measured in rat ventricular myocytes. H(2)O(2) induced an increase in I(Ca,L) amplitude and slowed inactivation of I(Ca)(,L). This oxidation-dependent facilitation (ODF) of I(Ca)(,L) was abolished by a CaMKII blocker KN-93, but not by its inactive analog KN-92, indicating that CaMKII is involved in ODF. ODF was not affected by replacement of external Ca(2+) with Ba(2+) or presence of EGTA in the internal solutions. However, ODF was abolished by adding BAPTA to the internal solution or by depleting sarcoplasmic reticulum (SR) Ca(2+) stores using caffeine and thapsigargin. Alkaline phosphatase, beta-iminoadenosine 5'-triphosphate (AMP-PNP), an autophosphorylation inhibitor autocamtide-2-related inhibitory peptide (AIP), or a catalytic domain blocker (CaM-KIINtide) did not affect ODF. In conclusion, oxidation-dependent facilitation of L-type Ca(2+) channels is mediated by oxidation-dependent CaMKII activation, in which local Ca(2+) increases induced by SR Ca(2+) release is required.
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Affiliation(s)
- Young-Hwan Song
- Department of Pediatrics, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea
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67
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Abiria SA, Colbran RJ. CaMKII associates with CaV1.2 L-type calcium channels via selected beta subunits to enhance regulatory phosphorylation. J Neurochem 2009; 112:150-61. [PMID: 19840220 DOI: 10.1111/j.1471-4159.2009.06436.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Calcium/calmodulin-dependent kinase II (CaMKII) facilitates L-type calcium channel (LTCC) activity physiologically, but may exacerbate LTCC-dependent pathophysiology. We previously showed that CaMKII forms stable complexes with voltage-gated calcium channel (VGCC) beta(1b) or beta(2a) subunits, but not with the beta(3) or beta(4) subunits (Grueter et al. 2008). CaMKII-dependent facilitation of Ca(V)1.2 LTCCs requires Thr498 phosphorylation in the beta(2a) subunit (Grueter et al. 2006), but the relationship of this modulation to CaMKII interactions with LTCC subunits is unknown. Here we show that CaMKII co-immunoprecipitates with forebrain LTCCs that contain Ca(V)1.2alpha(1) and beta(1) or beta(2) subunits, but is not detected in LTCC complexes containing beta(4) subunits. CaMKIIalpha can be specifically tethered to the I/II linker of Ca(V)1.2 alpha(1) subunits in vitro by the beta(1b) or beta(2a) subunits. Efficient targeting of CaMKIIalpha to the full-length Ca(V)1.2alpha(1) subunit in transfected HEK293 cells requires CaMKII binding to the beta(2a) subunit. Moreover, disruption of CaMKII binding substantially reduced phosphorylation of beta(2a) at Thr498 within the LTCC complex, without altering overall phosphorylation of Ca(V)1.2alpha(1) and beta subunits. These findings demonstrate a biochemical mechanism underlying LTCC facilitation by CaMKII.
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Affiliation(s)
- Sunday A Abiria
- Brain Institute, Vanderbilt University, Nashville, Tennessee, USA
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68
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Timmins JM, Ozcan L, Seimon TA, Li G, Malagelada C, Backs J, Backs T, Bassel-Duby R, Olson EN, Anderson ME, Tabas I. Calcium/calmodulin-dependent protein kinase II links ER stress with Fas and mitochondrial apoptosis pathways. J Clin Invest 2009; 119:2925-41. [PMID: 19741297 DOI: 10.1172/jci38857] [Citation(s) in RCA: 347] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 07/01/2009] [Indexed: 12/28/2022] Open
Abstract
ER stress-induced apoptosis is implicated in various pathological conditions, but the mechanisms linking ER stress-mediated signaling to downstream apoptotic pathways remain unclear. Using human and mouse cell culture and in vivo mouse models of ER stress-induced apoptosis, we have shown that cytosolic calcium resulting from ER stress induces expression of the Fas death receptor through a pathway involving calcium/calmodulin-dependent protein kinase IIgamma (CaMKIIgamma) and JNK. Remarkably, CaMKIIgamma was also responsible for processes involved in mitochondrial-dependent apoptosis, including release of mitochondrial cytochrome c and loss of mitochondrial membrane potential. CaMKII-dependent apoptosis was also observed in a number of cultured human and mouse cells relevant to ER stress-induced pathology, including cultured macrophages, endothelial cells, and neuronal cells subjected to proapoptotic ER stress. Moreover, WT mice subjected to systemic ER stress showed evidence of macrophage mitochondrial dysfunction and apoptosis, renal epithelial cell apoptosis, and renal dysfunction, and these effects were markedly reduced in CaMKIIgamma-deficient mice. These data support an integrated model in which CaMKII serves as a unifying link between ER stress and the Fas and mitochondrial apoptotic pathways. Our study also revealed what we believe to be a novel proapoptotic function for CaMKII, namely, promotion of mitochondrial calcium uptake. These findings raise the possibility that CaMKII inhibitors could be useful in preventing apoptosis in pathological settings involving ER stress-induced apoptosis.
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Affiliation(s)
- Jenelle M Timmins
- Department of Medicine, Columbia University, 630 West 168th Street, New York, NY 10032, USA
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69
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Benitah JP, Alvarez JL, Gómez AM. L-type Ca(2+) current in ventricular cardiomyocytes. J Mol Cell Cardiol 2009; 48:26-36. [PMID: 19660468 DOI: 10.1016/j.yjmcc.2009.07.026] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 07/09/2009] [Accepted: 07/27/2009] [Indexed: 12/24/2022]
Abstract
L-type Ca(2+) channels are mediators of Ca(2+) influx and the regulatory events accompanying it and are pivotal in the function and dysfunction of ventricular cardiac myocytes. L-type Ca(2+) channels are located in sarcolemma, including the T-tubules facing the sarcoplasmic reticulum junction, and are activated by membrane depolarization, but intracellular Ca(2+)-dependent inactivation limits Ca(2+) influx during action potential. I(CaL) is important in heart function because it triggers excitation-contraction coupling, modulates action potential shape and is involved in cardiac arrhythmia. L-type Ca(2+) channels are multi-subunit complexes that interact with several molecules involved in their regulations, notably by beta-adrenergic signaling. The present review highlights some of the recent findings on L-type Ca(2+) channel function, regulation, and alteration in acquired pathologies such as cardiac hypertrophy, heart failure and diabetic cardiomyopathy, as well as in inherited arrhythmic cardiac diseases such as Timothy and Brugada syndromes.
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70
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Wang WY, Hao LY, Minobe E, Saud ZA, Han DY, Kameyama M. CaMKII phosphorylates a threonine residue in the C-terminal tail of Cav1.2 Ca(2+) channel and modulates the interaction of the channel with calmodulin. J Physiol Sci 2009; 59:283-90. [PMID: 19340532 PMCID: PMC10717815 DOI: 10.1007/s12576-009-0033-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Accepted: 02/23/2009] [Indexed: 11/26/2022]
Abstract
We have previously found that both CaMKII-mediated phosphorylation and calmodulin (CaM) binding to the channels are required for maintaining basal activity of the Cav1.2 Ca(2+) channels. In this study, we investigated the hypothetical CaMKII phosphorylation site on Cav1.2 that contributes to the channel regulation. We found that CaMKII phosphorylates the Thr1603 residue (Thr1604 in rabbit) within the preIQ region in the C-terminal tail of the guinea-pig Cav1.2 channel. Mutation of Thr1603 to Asp (T1603D) slowed the run-down of the channel in inside-out patch mode and abolished the time-dependency of the CaM's effects to reverse run-down. We also found that CaMKII-mediated phosphorylation of the proximal C-terminal fragment (CT1) increased, while dephosphorylation of CT1 decreased its binding with CaM. These findings suggest that CaMKII regulates the CaM binding to the channel, and thereby maintains basal activity of the Cav1.2 Ca(2+) channel.
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Affiliation(s)
- Wu-Yang Wang
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544 Japan
| | - Li-Ying Hao
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544 Japan
- Department of Pharmaceutical Toxicology, School of Pharmaceutical Sciences, China Medical University, 92 Beier Road, 110001 Shenyang, China
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544 Japan
| | - Zahangir Alam Saud
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544 Japan
| | - Dong-Yun Han
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544 Japan
- Department of Pharmaceutical Toxicology, School of Pharmaceutical Sciences, China Medical University, 92 Beier Road, 110001 Shenyang, China
| | - Masaki Kameyama
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544 Japan
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71
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Tbx5-mediated expression of Ca2+/calmodulin-dependent protein kinase II is necessary for zebrafish cardiac and pectoral fin morphogenesis. Dev Biol 2009; 330:175-84. [DOI: 10.1016/j.ydbio.2009.03.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 03/24/2009] [Accepted: 03/26/2009] [Indexed: 01/30/2023]
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72
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Dai S, Hall DD, Hell JW. Supramolecular assemblies and localized regulation of voltage-gated ion channels. Physiol Rev 2009; 89:411-52. [PMID: 19342611 DOI: 10.1152/physrev.00029.2007] [Citation(s) in RCA: 264] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
This review addresses the localized regulation of voltage-gated ion channels by phosphorylation. Comprehensive data on channel regulation by associated protein kinases, phosphatases, and related regulatory proteins are mainly available for voltage-gated Ca2+ channels, which form the main focus of this review. Other voltage-gated ion channels and especially Kv7.1-3 (KCNQ1-3), the large- and small-conductance Ca2+-activated K+ channels BK and SK2, and the inward-rectifying K+ channels Kir3 have also been studied to quite some extent and will be included. Regulation of the L-type Ca2+ channel Cav1.2 by PKA has been studied most thoroughly as it underlies the cardiac fight-or-flight response. A prototypical Cav1.2 signaling complex containing the beta2 adrenergic receptor, the heterotrimeric G protein Gs, adenylyl cyclase, and PKA has been identified that supports highly localized via cAMP. The type 2 ryanodine receptor as well as AMPA- and NMDA-type glutamate receptors are in close proximity to Cav1.2 in cardiomyocytes and neurons, respectively, yet independently anchor PKA, CaMKII, and the serine/threonine phosphatases PP1, PP2A, and PP2B, as is discussed in detail. Descriptions of the structural and functional aspects of the interactions of PKA, PKC, CaMKII, Src, and various phosphatases with Cav1.2 will include comparisons with analogous interactions with other channels such as the ryanodine receptor or ionotropic glutamate receptors. Regulation of Na+ and K+ channel phosphorylation complexes will be discussed in separate papers. This review is thus intended for readers interested in ion channel regulation or in localization of kinases, phosphatases, and their upstream regulators.
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Affiliation(s)
- Shuiping Dai
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242-1109, USA
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73
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Findeisen F, Minor DL. Disruption of the IS6-AID linker affects voltage-gated calcium channel inactivation and facilitation. ACTA ACUST UNITED AC 2009; 133:327-43. [PMID: 19237593 PMCID: PMC2654080 DOI: 10.1085/jgp.200810143] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Two processes dominate voltage-gated calcium channel (CaV) inactivation: voltage-dependent inactivation (VDI) and calcium-dependent inactivation (CDI). The CaVβ/CaVα1-I-II loop and Ca2+/calmodulin (CaM)/CaVα1–C-terminal tail complexes have been shown to modulate each, respectively. Nevertheless, how each complex couples to the pore and whether each affects inactivation independently have remained unresolved. Here, we demonstrate that the IS6–α-interaction domain (AID) linker provides a rigid connection between the pore and CaVβ/I-II loop complex by showing that IS6-AID linker polyglycine mutations accelerate CaV1.2 (L-type) and CaV2.1 (P/Q-type) VDI. Remarkably, mutations that either break the rigid IS6-AID linker connection or disrupt CaVβ/I-II association sharply decelerate CDI and reduce a second Ca2+/CaM/CaVα1–C-terminal–mediated process known as calcium-dependent facilitation. Collectively, the data strongly suggest that components traditionally associated solely with VDI, CaVβ and the IS6-AID linker, are essential for calcium-dependent modulation, and that both CaVβ-dependent and CaM-dependent components couple to the pore by a common mechanism requiring CaVβ and an intact IS6-AID linker.
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Affiliation(s)
- Felix Findeisen
- Cardiovascular Research Institute, Department of Biochemistry and Biophysics, California Institute for Quantitative Biosciences, University of California, San Francisco, CA 94158, USA
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74
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Hashambhoy YL, Winslow RL, Greenstein JL. CaMKII-induced shift in modal gating explains L-type Ca(2+) current facilitation: a modeling study. Biophys J 2009; 96:1770-85. [PMID: 19254537 PMCID: PMC2717283 DOI: 10.1016/j.bpj.2008.11.055] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Accepted: 11/21/2008] [Indexed: 11/23/2022] Open
Abstract
Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) plays an important role in L-type Ca(2+) channel (LCC) facilitation: the Ca(2+)-dependent augmentation of Ca(2+) current (I(CaL)) exhibited during rapid repeated depolarization. Multiple mechanisms may underlie facilitation, including an increased rate of recovery from Ca(2+)-dependent inactivation and a shift in modal gating distribution from mode 1, the dominant mode of LCC gating, to mode 2, a mode in which openings are prolonged. We hypothesized that the primary mechanism underlying facilitation is the shift in modal gating distribution resulting from CaMKII-mediated LCC phosphorylation. We developed a stochastic model describing the dynamic interactions among CaMKII, LCCs, and phosphatases as a function of dyadic Ca(2+) and calmodulin levels, and we incorporated it into an integrative model of the canine ventricular myocyte. The model reproduces behaviors at physiologic protein levels and allows for dynamic transition between modes, depending on the LCC phosphorylation state. Simulations showed that a CaMKII-dependent shift in LCC distribution toward mode 2 accounted for the I(CaL) positive staircase. Moreover, simulations demonstrated that experimentally observed changes in LCC inactivation and recovery kinetics may arise from modal gating shifts, rather than from changes in intrinsic inactivation properties. The model therefore serves as a powerful tool for interpreting I(CaL) experiments.
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Affiliation(s)
| | | | - Joseph L. Greenstein
- Institute for Computational Medicine, Center for Cardiovascular Bioinformatics and Modeling, and the Whitaker Biomedical Engineering Institute, the Johns Hopkins University, Baltimore, Maryland
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75
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Sametsky EA, Disterhoft JF, Ohno M. Autophosphorylation of alphaCaMKII downregulates excitability of CA1 pyramidal neurons following synaptic stimulation. Neurobiol Learn Mem 2009; 92:120-3. [PMID: 19245842 DOI: 10.1016/j.nlm.2009.02.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Revised: 02/17/2009] [Accepted: 02/18/2009] [Indexed: 11/30/2022]
Abstract
It has been well documented that alpha-calcium/calmodulin-dependent protein kinase II (alphaCaMKII) is central to synaptic plasticity such as long-term potentiation, an activity-dependent strengthening of synapses that is thought to underlie certain types of learning and memory. However, the mechanisms by which alphaCaMKII may regulate neuronal excitability remain unclear. Here, we report that alphaCaMKII knock-in mice with a targeted T286A point mutation that prevents its autophosphorylation (alphaCaMKII(T286A)) showed increased excitability of CA1 pyramidal neurons compared with wild-type controls, as measured by a decrease in the slow component of post-burst afterhyperpolarization (sAHP) following high-frequency stimulation of Schaffer collateral afferent fibers. In contrast, AHP was indistinguishable between alphaCaMKII(T286A) and wild-type mice when it was evoked by somatic current injections, indicating that the hyperexcitability is observed specifically in response to synaptic stimulation in this mutant. Taken together, our results suggest that alphaCaMKII functions to downregulate CA1 neuron excitability following synaptic stimulation, presumably supporting the functionally adaptive modulation of excitability during hippocampal learning or providing a negative feedback mechanism that would prevent neurons from becoming hyperexcitable and promote network stability.
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Affiliation(s)
- Evgeny A Sametsky
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611-3008, USA
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76
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Ravindran A, Kobrinsky E, Lao QZ, Soldatov NM. Functional properties of the CaV1.2 calcium channel activated by calmodulin in the absence of alpha2delta subunits. Channels (Austin) 2009; 3:25-31. [PMID: 19106618 PMCID: PMC2772127 DOI: 10.4161/chan.3.1.7498] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Voltage-activated CaV1.2 calcium channels require association of the pore-forming alpha1C subunit with accessory CaVbeta and alpha2delta subunits. Binding of a single calmodulin (CaM) to alpha1C supports Ca2+-dependent inactivation (CDI). The human CaV1.2 channel is silent in the absence of CaVbeta and/or alpha2delta. Recently, we found that coexpression of exogenous CaM (CaMex) supports plasma membrane targeting, gating facilitation and CDI of the channel in the absence of CaVbeta. Here we discovered that CaMex and its Ca2+-insensitive mutant (CaM1234) rendered active alpha1C/CaVbeta channel in the absence of alpha2delta. Coexpression of CaMex with alpha1C and beta2d in calcium-channel-free COS-1 cells recovered gating of the channel and supported CDI. Voltage-dependence of activation was shifted by approximately +40 mV to depolarization potentials. The calcium current reached maximum at +40 mV (20 mM Ca2+) and exhibited approximately 3 times slower activation and 5 times slower inactivation kinetics compared to the wild-type channel. Furthermore, both CaMex and CaM1234 accelerated recovery from inactivation and induced facilitation of the calcium current by strong depolarization prepulse, the properties absent from the human vascular/neuronal CaV1.2 channel. The data suggest a previously unknown action of CaM that in the presence of CaVbeta; translates into activation of the alpha2delta-deficient calcium channel and alteration of its properties.
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Affiliation(s)
- Arippa Ravindran
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Evgeny Kobrinsky
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Qi Zong Lao
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Nikolai M. Soldatov
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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77
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Kim EY, Rumpf CH, Fujiwara Y, Cooley ES, Van Petegem F, Minor DL. Structures of CaV2 Ca2+/CaM-IQ domain complexes reveal binding modes that underlie calcium-dependent inactivation and facilitation. Structure 2008; 16:1455-67. [PMID: 18940602 DOI: 10.1016/j.str.2008.07.010] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 07/21/2008] [Accepted: 07/22/2008] [Indexed: 01/22/2023]
Abstract
Calcium influx drives two opposing voltage-activated calcium channel (Ca(V)) self-modulatory processes: calcium-dependent inactivation (CDI) and calcium-dependent facilitation (CDF). Specific Ca(2+)/calmodulin (Ca(2+)/CaM) lobes produce CDI and CDF through interactions with the Ca(V)alpha(1) subunit IQ domain. Curiously, Ca(2+)/CaM lobe modulation polarity appears inverted between Ca(V)1s and Ca(V)2s. Here, we present crystal structures of Ca(V)2.1, Ca(V)2.2, and Ca(V)2.3 Ca(2+)/CaM-IQ domain complexes. All display binding orientations opposite to Ca(V)1.2 with a physical reversal of the CaM lobe positions relative to the IQ alpha-helix. Titration calorimetry reveals lobe competition for a high-affinity site common to Ca(V)1 and Ca(V)2 IQ domains that is occupied by the CDI lobe in the structures. Electrophysiological experiments demonstrate that the N-terminal Ca(V)2 Ca(2+)/C-lobe anchors affect CDF. Together, the data unveil the remarkable structural plasticity at the heart of Ca(V) feedback modulation and indicate that Ca(V)1 and Ca(V)2 IQ domains bear a dedicated CDF site that exchanges Ca(2+)/CaM lobe occupants.
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Affiliation(s)
- Eun Young Kim
- Cardiovascular Research Institute, Department of Biochemistry and Biophysics, California Institute for Quantitative Biosciences, University of California, San Francisco, CA 94158-2330, USA
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78
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Wheeler DG, Barrett CF, Groth RD, Safa P, Tsien RW. CaMKII locally encodes L-type channel activity to signal to nuclear CREB in excitation-transcription coupling. J Cell Biol 2008; 183:849-63. [PMID: 19047462 PMCID: PMC2592819 DOI: 10.1083/jcb.200805048] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Accepted: 10/29/2008] [Indexed: 12/11/2022] Open
Abstract
Communication between cell surface proteins and the nucleus is integral to many cellular adaptations. In the case of ion channels in excitable cells, the dynamics of signaling to the nucleus are particularly important because the natural stimulus, surface membrane depolarization, is rapidly pulsatile. To better understand excitation-transcription coupling we characterized the dependence of cAMP response element-binding protein phosphorylation, a critical step in neuronal plasticity, on the level and duration of membrane depolarization. We find that signaling strength is steeply dependent on depolarization, with sensitivity far greater than hitherto recognized. In contrast, graded blockade of the Ca(2+) channel pore has a remarkably mild effect, although some Ca(2+) entry is absolutely required. Our data indicate that Ca(2+)/CaM-dependent protein kinase II acting near the channel couples local Ca(2+) rises to signal transduction, encoding the frequency of Ca(2+) channel openings rather than integrated Ca(2+) flux-a form of digital logic.
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Affiliation(s)
- Damian G Wheeler
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
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79
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Abstract
Calcium/calmodulin-dependent kinase II (CaMKII) is a multifunctional serine/threonine kinase widely distributed in a number of tissue types. Activation of CaMKII has been linked to important downstream physiological processes, including apoptosis, hypertrophy, and arrhythmia in the heart. Pharmacological or genetic inhibition of CaMKII has been shown to improve health outcomes in a number of animal models. In this review, we summarize the structural and functional properties of CaMKII and detail its role in cardiac arrhythmia, structural heart disease, and sudden death.
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Affiliation(s)
- Jeffrey R Erickson
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242-1109, USA
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80
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Smith JAH, Kohn TA, Chetty AK, Ojuka EO. CaMK activation during exercise is required for histone hyperacetylation and MEF2A binding at the MEF2 site on the Glut4 gene. Am J Physiol Endocrinol Metab 2008; 295:E698-704. [PMID: 18647882 DOI: 10.1152/ajpendo.00747.2007] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role of CaMK II in regulating GLUT4 expression in response to intermittent exercise was investigated. Wistar rats completed 5 x 17-min bouts of swimming after receiving 5 mg/kg KN93 (a CaMK II inhibitor), KN92 (an analog of KN93 that does not inhibit CaMK II), or an equivalent volume of vehicle. Triceps muscles that were harvested at 0, 6, or 18 h postexercise were assayed for 1) CaMK II phosphorylation by Western blot, 2) acetylation of histone H3 at the Glut4 MEF2 site by chromatin immunoprecipitation (ChIP) assay, 3) bound MEF2A at the Glut4 MEF2 cis-element by ChIP, and 4) GLUT4 expression by RT-PCR and Western blot. Compared with controls, exercise caused a twofold increase in CaMK II phosphorylation. Immunohistochemical stains indicated increased CaMK II phosphorylation in nuclear and perinuclear regions of the muscle fiber. Acetylation of histone H3 in the region surrounding the MEF2 binding site on the Glut4 gene and the amount of MEF2A that bind to the site increased approximately twofold postexercise. GLUT4 mRNA and protein increased approximately 2.2- and 1.8-fold, respectively, after exercise. The exercise-induced increases in CaMK II phosphorylation, histone H3 acetylation, MEF2A binding, and GLUT4 expression were attenuated or abolished when KN93 was administered to rats prior to exercise. KN92 did not affect the increases in pCaMK II and GLUT4. These data support the hypothesis that CaMK II activation by exercise increases GLUT4 expression via increased accessibility of MEF2A to its cis-element on the gene.
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Affiliation(s)
- James A H Smith
- Dept. of Human Biology, Univ. of Cape Town, Newlands, 7725 South Africa
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81
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Wang Y, Tandan S, Cheng J, Yang C, Nguyen L, Sugianto J, Johnstone JL, Sun Y, Hill JA. Ca2+/calmodulin-dependent protein kinase II-dependent remodeling of Ca2+ current in pressure overload heart failure. J Biol Chem 2008; 283:25524-25532. [PMID: 18622016 DOI: 10.1074/jbc.m803043200] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) activity is increased in heart failure (HF), a syndrome characterized by markedly increased risk of arrhythmia. Activation of CaMKII increases peak L-type Ca(2+) current (I(Ca)) and slows I(Ca) inactivation. Whether these events are linked mechanistically is unknown. I(Ca) was recorded in acutely dissociated subepicardial and subendocardial murine left ventricular (LV) myocytes using the whole cell patch clamp method. Pressure overload heart failure was induced by surgical constriction of the thoracic aorta. I(Ca) density was significantly larger in subepicardial myocytes than in subendocardial/myocytes. Similar patterns were observed in the cell surface expression of alpha1c, the channel pore-forming subunit. In failing LV, I(Ca) density was increased proportionately in both cell types, and the time course of I(Ca) inactivation was slowed. This typical pattern of changes suggested a role of CaMKII. Consistent with this, measurements of CaMKII activity revealed a 2-3-fold increase (p < 0.05) in failing LV. To test for a causal link, we measured frequency-dependent I(Ca) facilitation. In HF myocytes, this CaMKII-dependent process could not be induced, suggesting already maximal activation. Internal application of active CaMKII in failing myocytes did not elicit changes in I(Ca). Finally, CaMKII inhibition by internal diffusion of a specific peptide inhibitor reduced I(Ca) density and inactivation time course to similar levels in control and HF myocytes. I(Ca) density manifests a significant transmural gradient, and this gradient is preserved in heart failure. Activation of CaMKII, a known pro-arrhythmic molecule, is a major contributor to I(Ca) remodeling in load-induced heart failure.
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Affiliation(s)
- Yanggan Wang
- Department of Internal Medicine (Cardiology), Dallas, Texas 75390-8573
| | - Samvit Tandan
- Department of Internal Medicine (Cardiology), Dallas, Texas 75390-8573
| | - Jun Cheng
- Department of Internal Medicine (Cardiology), Dallas, Texas 75390-8573
| | - Chunmei Yang
- Department of Internal Medicine (Cardiology), Dallas, Texas 75390-8573
| | - Lan Nguyen
- Department of Internal Medicine (Cardiology), Dallas, Texas 75390-8573
| | - Jessica Sugianto
- Department of Internal Medicine (Cardiology), Dallas, Texas 75390-8573
| | - Janet L Johnstone
- Department of Internal Medicine (Cardiology), Dallas, Texas 75390-8573
| | - Yuyang Sun
- Department of Pediatrics, Emory University, Atlanta, Georgia 30322
| | - Joseph A Hill
- Department of Internal Medicine (Cardiology), Dallas, Texas 75390-8573; Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8573 and the.
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82
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O-Uchi J, Sasaki H, Morimoto S, Kusakari Y, Shinji H, Obata T, Hongo K, Komukai K, Kurihara S. Interaction of α
1
-Adrenoceptor Subtypes With Different G Proteins Induces Opposite Effects on Cardiac L-type Ca
2+
Channel. Circ Res 2008; 102:1378-88. [DOI: 10.1161/circresaha.107.167734] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We examined the effect of α
1
-adrenoceptor subtype-specific stimulation on L-type Ca
2+
current (
I
Ca
) and elucidated the subtype-specific intracellular mechanisms for the regulation of L-type Ca
2+
channels in isolated rat ventricular myocytes. We confirmed the protein expression of α
1A
- and α
1B
-adrenoceptor subtypes at the transverse tubules (T-tubules) and found that simultaneous stimulation of these 2 receptor subtypes by nonsubtype selective agonist, phenylephrine, showed 2 opposite effects on
I
Ca
(transient decrease followed by sustained increase). However, selective α
1A
-adrenoceptor stimulation (≥0.1 μmol/L A61603) only potentiated
I
Ca
, and selective α
1B
-adrenoceptor stimulation (10 μmol/L phenylephrine with 2 μ mol/L WB4101) only decreased
I
Ca
. The positive effect by α
1A
-adrenoceptor stimulation was blocked by the inhibition of phospholipase C (PLC), protein kinase C (PKC), or Ca
2+
/calmodulin-dependent protein kinase II (CaMKII). The negative effect by α
1B
-adrenoceptor stimulation disappeared after the treatment of pertussis toxin or by the prepulse depolarization, but was not attriburable to the inhibition of cAMP-dependent pathway. The translocation of PKCδ and ε to the T-tubules was observed only after α
1A
-adrenoceptor stimulation, but not after α
1B
-adrenoceptor stimulation. Immunoprecipitaion analysis revealed that α
1A
-adrenoceptor was associated with G
q/11
, but α
1B
-adrenoceptor interacted with one of the pertussis toxin-sensitive G proteins, G
o
. These findings demonstrated that the interactions of α
1
-adrenoceptor subtypes with different G proteins elicit the formation of separate signaling cascades, which produce the opposite effects on
I
Ca
. The coupling of α
1A
-adrenoceptor with G
q/11
-PLC-PKC-CaMKII pathway potentiates
I
Ca
. In contrast, α
1B
-adrenoceptor interacts with G
o
, of which the βγ-complex might directly inhibit the channel activity at T-tubules.
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Affiliation(s)
- Jin O-Uchi
- From the Department of Cell Physiology (J.O.-U., S.M., Y.K., S.K.), the Division of Molecular Cell Biology (H.Sasaki, T.O.), the Division of Cardiology (S.M., K.H., K.K.), and the Department of Bacteriology (H.Shinji), The Jikei University School of Medicine, Tokyo, Japan
| | - Hiroyuki Sasaki
- From the Department of Cell Physiology (J.O.-U., S.M., Y.K., S.K.), the Division of Molecular Cell Biology (H.Sasaki, T.O.), the Division of Cardiology (S.M., K.H., K.K.), and the Department of Bacteriology (H.Shinji), The Jikei University School of Medicine, Tokyo, Japan
| | - Satoshi Morimoto
- From the Department of Cell Physiology (J.O.-U., S.M., Y.K., S.K.), the Division of Molecular Cell Biology (H.Sasaki, T.O.), the Division of Cardiology (S.M., K.H., K.K.), and the Department of Bacteriology (H.Shinji), The Jikei University School of Medicine, Tokyo, Japan
| | - Yoichiro Kusakari
- From the Department of Cell Physiology (J.O.-U., S.M., Y.K., S.K.), the Division of Molecular Cell Biology (H.Sasaki, T.O.), the Division of Cardiology (S.M., K.H., K.K.), and the Department of Bacteriology (H.Shinji), The Jikei University School of Medicine, Tokyo, Japan
| | - Hitomi Shinji
- From the Department of Cell Physiology (J.O.-U., S.M., Y.K., S.K.), the Division of Molecular Cell Biology (H.Sasaki, T.O.), the Division of Cardiology (S.M., K.H., K.K.), and the Department of Bacteriology (H.Shinji), The Jikei University School of Medicine, Tokyo, Japan
| | - Toru Obata
- From the Department of Cell Physiology (J.O.-U., S.M., Y.K., S.K.), the Division of Molecular Cell Biology (H.Sasaki, T.O.), the Division of Cardiology (S.M., K.H., K.K.), and the Department of Bacteriology (H.Shinji), The Jikei University School of Medicine, Tokyo, Japan
| | - Kenichi Hongo
- From the Department of Cell Physiology (J.O.-U., S.M., Y.K., S.K.), the Division of Molecular Cell Biology (H.Sasaki, T.O.), the Division of Cardiology (S.M., K.H., K.K.), and the Department of Bacteriology (H.Shinji), The Jikei University School of Medicine, Tokyo, Japan
| | - Kimiaki Komukai
- From the Department of Cell Physiology (J.O.-U., S.M., Y.K., S.K.), the Division of Molecular Cell Biology (H.Sasaki, T.O.), the Division of Cardiology (S.M., K.H., K.K.), and the Department of Bacteriology (H.Shinji), The Jikei University School of Medicine, Tokyo, Japan
| | - Satoshi Kurihara
- From the Department of Cell Physiology (J.O.-U., S.M., Y.K., S.K.), the Division of Molecular Cell Biology (H.Sasaki, T.O.), the Division of Cardiology (S.M., K.H., K.K.), and the Department of Bacteriology (H.Shinji), The Jikei University School of Medicine, Tokyo, Japan
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84
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Chen X, Zhang X, Harris DM, Piacentino V, Berretta RM, Margulies KB, Houser SR. Reduced effects of BAY K 8644 on L-type Ca2+ current in failing human cardiac myocytes are related to abnormal adrenergic regulation. Am J Physiol Heart Circ Physiol 2008; 294:H2257-67. [PMID: 18359894 DOI: 10.1152/ajpheart.01335.2007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Abnormal L-type Ca(2+) channel (LTCC, also named Cav1.2) density and regulation are important contributors to depressed contractility in failing hearts. The LTCC agonist BAY K 8644 (BAY K) has reduced inotropic effects on failing myocardium. We hypothesized that BAY K effects on the LTCC current (I(CaL)) in failing myocytes would be reduced because of increased basal activity. Since support of the failing heart with a left ventricular assist device (LVAD) improves contractility and adrenergic responses, we further hypothesized that BAY K effects on I(CaL) would be restored in LVAD-supported failing hearts. We tested our hypotheses in human ventricular myocytes (HVMs) isolated from nonfailing (NF), failing (F), and LVAD-supported failing hearts. We found that 1) BAY K had smaller effects on I(CaL) in F HVMs compared with NF HVMs; 2) BAY K had diminished effects on I(CaL) in NF HVM pretreated with isoproterenol (Iso) or dibutyryl cyclic AMP (DBcAMP); 3) BAY K effects on I(CaL) in F HVMs pretreated with acetylcholine (ACh) were normalized; 4) Iso had no effect on NF HVMs pretreated with BAY K; 5) BAY K effects on I(CaL) in LVAD HVMs were similar to those in NF HVMs; 6) BAY K effects were reduced in LVAD HVMs pretreated with Iso or DBcAMP; 7) Iso had no effect on I(CaL) in LVAD HVMs pretreated with BAY K. Collectively, these results suggest that the decreased BAY K effects on LTCC in F HVMs are caused by increased basal channel activity, which should contribute to abnormal contractility reserve.
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Affiliation(s)
- Xiongwen Chen
- Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, 3420 North Broad Street, Philadelphia, PA 19140, USA
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85
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Grueter CE, Abiria SA, Wu Y, Anderson ME, Colbran RJ. Differential regulated interactions of calcium/calmodulin-dependent protein kinase II with isoforms of voltage-gated calcium channel beta subunits. Biochemistry 2008; 47:1760-7. [PMID: 18205403 DOI: 10.1021/bi701755q] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ca2+/calmodulin-dependent protein kinase II (CaMKII) phosphorylates the beta2a subunit of voltage-gated Ca2+ channels at Thr498 to facilitate cardiac L-type Ca2+ channels. CaMKII colocalizes with beta2a in cardiomyocytes and also binds to a domain in beta2a that contains Thr498 and exhibits an amino acid sequence similarity to the CaMKII autoinhibitory domain and to a CaMKII binding domain in the NMDA receptor NR2B subunit (Grueter, C. E. et al. (2006) Mol. Cell 23, 641). Here, we explore the selectivity of the actions of CaMKII among Ca2+ channel beta subunit isoforms. CaMKII phosphorylates the beta1b, beta2a, beta3, and beta4 isoforms with similar initial rates and final stoichiometries of 6-12 mol of phosphate per mol of protein. However, activated/autophosphorylated CaMKII binds to beta1b and beta2a with a similar apparent affinity but does not bind to beta3 or beta4. Prephosphorylation of beta1b and beta2a by CaMKII substantially reduces the binding of autophosphorylated CaMKII. Residues surrounding Thr498 in beta2a are highly conserved in beta1b but are different in beta3 and beta4. Site-directed mutagenesis of this domain in beta2a showed that Thr498 phosphorylation promotes dissociation of CaMKII-beta2a complexes in vitro and reduces interactions of CaMKII with beta2a in cells. Mutagenesis of Leu493 to Ala substantially reduces CaMKII binding in vitro and in intact cells but does not interfere with beta2a phosphorylation at Thr498. In combination, these data show that phosphorylation dynamically regulates the interactions of specific isoforms of the Ca2+ channel beta subunits with CaMKII.
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Affiliation(s)
- Chad E Grueter
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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86
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Vadysirisack DD, Chen ESW, Zhang Z, Tsai MD, Chang GD, Jhiang SM. Identification of in vivo phosphorylation sites and their functional significance in the sodium iodide symporter. J Biol Chem 2007; 282:36820-8. [PMID: 17913707 DOI: 10.1074/jbc.m706817200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Na+/I- symporter (NIS)-mediated iodide uptake activity is the basis for targeted radioiodide ablation of thyroid cancers. Although it has been shown that NIS protein is phosphorylated, neither the in vivo phosphorylation sites nor their functional significance has been reported. In this study, Ser-43, Thr-49, Ser-227, Thr-577, and Ser-581 were identified as in vivo NIS phosphorylation sites by mass spectrometry. Kinetic analysis of NIS mutants of the corresponding phosphorylated amino acid residue indicated that the velocity of iodide transport of NIS is modulated by the phosphorylation status of Ser-43 and Ser-581. We also found that the phosphorylation status of Thr-577 may be important for NIS protein stability and that the phosphorylation status of Ser-227 is functionally silent. Thr-49 appears to be critical for proper local structure/conformation of NIS because mutation of Thr-49 to alanine, aspartic acid, or serine results in reduced NIS activity without alterations in total or cell surface NIS protein levels. Taken together, we showed that NIS protein levels and functional activity could be modulated by phosphorylation through distinct mechanisms.
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Affiliation(s)
- Douangsone D Vadysirisack
- Integrated Biomedical Science Graduate Program, Department of Physiology and Cell Biology, Ohio State University, Columbus 43210, USA
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87
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Kobayashi T, Yamada Y, Fukao M, Tsutsuura M, Tohse N. Regulation of Cav1.2 current: interaction with intracellular molecules. J Pharmacol Sci 2007; 103:347-53. [PMID: 17409629 DOI: 10.1254/jphs.cr0070012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Ca(V)1.2 (alpha(1c)) is a pore-forming subunit of the voltage-dependent L-type calcium channel and is expressed in many tissues. The beta and alpha(2)/delta subunits are auxiliary subunits that affect the kinetics and the expression of Ca(V)1.2. In addition to the beta and alpha(2)/delta subunits, several molecules have been reported to be involved in the regulation of Ca(V)1.2 current. Calmodulin, CaBP1 (calcium-binding protein-1), CaMKII (calcium/calmodulin-dependent protein kinase II), AKAPs (A-kinase anchoring proteins), phosphatases, Caveolin-3, beta(2)-adrenergic receptor, PDZ domain proteins, sorcin, SNARE proteins, synaptotagmin, CSN5, RGK family, and AHNAK1 have all been reported to interact with Ca(V)1.2 and the beta subunit. This review focuses on the effect of these molecules on Ca(V)1.2 current.
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Affiliation(s)
- Takeshi Kobayashi
- Department of Cellular Physiology and Signal Transduction, Sapporo Medical University School of Medicine, Sapporo, Japan.
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88
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Pitt GS. Calmodulin and CaMKII as molecular switches for cardiac ion channels: Fig. 1. Cardiovasc Res 2007; 73:641-7. [PMID: 17137569 DOI: 10.1016/j.cardiores.2006.10.019] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 10/20/2006] [Accepted: 10/25/2006] [Indexed: 10/23/2022] Open
Abstract
Because changes in intracellular Ca(2+) concentration are the final signals of electrical activity in excitable cells, many mechanisms have evolved to regulate Ca(2+) influx. Among the most important are those pathways that directly regulate the ion channels responsible for regulating and generating the Ca(2+) influx signal. Recent work has demonstrated that the Ca(2+) binding protein calmodulin (CaM) and the Ca(2+)/CaM-sensitive kinase CaMKII are important modulators of cardiac ion channels. Thus, Ca(2+) participates in feedback modulation to control electrical activity. This review highlights various mechanisms by which CaM and CaMKII regulate cardiovascular ion channel activity and presents a novel model for CaMKII regulation of Ca(V)1.2 Ca(2+) channel function.
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Affiliation(s)
- Geoffrey S Pitt
- Department of Medicine, Division of Cardiology, College of Physicians and Surgeons of Columbia University, 630 W 168th St, PH 7W 318, New York, NY 10032, USA.
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89
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Anderson ME. Multiple downstream proarrhythmic targets for calmodulin kinase II: Moving beyond an ion channel-centric focus. Cardiovasc Res 2007; 73:657-66. [PMID: 17254559 DOI: 10.1016/j.cardiores.2006.12.009] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 12/08/2006] [Accepted: 12/11/2006] [Indexed: 11/21/2022] Open
Abstract
The multifunctional Ca(2+) calmodulin-dependent protein kinase II (CaMKII) has emerged as a pro-arrhythmic signaling molecule. CaMKII can participate in arrhythmia signaling by effects on ion channel proteins, intracellular Ca(2+) uptake and release, regulation of cell death, and by activation of hypertrophic signaling pathways. The pleuripotent nature of CaMKII is reminiscent of another serine-threonine kinase, protein kinase A (PKA), which shares many of the same protein targets and is the downstream kinase most associated with beta-adrenergic receptor stimulation. The ability of CaMKII to localize and coordinate activity of multiple protein targets linked to Ca(2+) signaling set CaMKII apart from other "traditional" arrhythmia drug targets, such as ion channel proteins. This review will discuss some of the biology of CaMKII and focus on work that has been done on molecular, cellular, and whole animal models that together build a case for CaMKII as a pro-arrhythmic signal and as a potential therapeutic target for arrhythmias and structural heart disease.
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Affiliation(s)
- Mark E Anderson
- University of Iowa, Carver College of Medicine, Department of Internal Medicine, 200 Hawkins Drive, E315-A1 GH, Iowa City, IA 52242 USA.
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90
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Calin-Jageman I, Yu K, Hall RA, Mei L, Lee A. Erbin enhances voltage-dependent facilitation of Ca(v)1.3 Ca2+ channels through relief of an autoinhibitory domain in the Ca(v)1.3 alpha1 subunit. J Neurosci 2007; 27:1374-85. [PMID: 17287512 PMCID: PMC6673595 DOI: 10.1523/jneurosci.5191-06.2007] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Revised: 12/27/2006] [Accepted: 12/29/2006] [Indexed: 11/21/2022] Open
Abstract
Ca(v)1.3 (L-type) voltage-gated Ca2+ channels have emerged as key players controlling Ca2+ signals at excitatory synapses. Compared with the more widely expressed Ca(v)1.2 L-type channel, relatively little is known about the mechanisms that regulate Ca(v)1.3 channels. Here, we describe a new role for the PSD-95 (postsynaptic density-95)/Discs large/ZO-1 (zona occludens-1) (PDZ) domain-containing protein, erbin, in directly potentiating Ca(v)1.3. Erbin specifically forms a complex with Ca(v)1.3, but not Ca(v)1.2, in transfected cells. The significance of erbin/Ca(v)1.3 interactions is supported by colocalization in somatodendritic domains of cortical neurons in culture and coimmunoprecipitation from rat brain lysates. In electrophysiological recordings, erbin augments facilitation of Ca(v)1.3 currents by a conditioning prepulse, a process known as voltage-dependent facilitation (VDF). This effect requires a direct interaction of the erbin PDZ domain with a PDZ recognition site in the C-terminal domain (CT) of the long variant of the Ca(v)1.3 alpha1 subunit (alpha1 1.3). Compared with Ca(v)1.3, the Ca(v)1.3b splice variant, which lacks a large fraction of the alpha1 1.3 CT, shows robust VDF that is not further affected by erbin. When coexpressed as an independent entity with Ca(v)1.3b or Ca(v)1.3 plus erbin, the alpha1 1.3 CT strongly suppresses VDF, signifying an autoinhibitory function of this part of the channel. These modulatory effects of erbin, but not alpha1 1.3 CT, depend on the identity of the auxiliary Ca2+ channel beta subunit. Our findings reveal a novel mechanism by which PDZ interactions and alternative splicing of alpha1 1.3 may influence activity-dependent regulation of Ca(v)1.3 channels at the synapse.
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Affiliation(s)
- Irina Calin-Jageman
- Department of Pharmacology and
- Center for Neurodegenerative Disease, Emory University, Atlanta, Georgia 30322, and
| | - Kuai Yu
- Department of Pharmacology and
- Center for Neurodegenerative Disease, Emory University, Atlanta, Georgia 30322, and
| | | | - Lin Mei
- Program of Developmental Neurobiology, Institute of Molecular Medicine and Genetics and Department of Neurology, Medical College of Georgia, Augusta, Georgia 30912
| | - Amy Lee
- Department of Pharmacology and
- Center for Neurodegenerative Disease, Emory University, Atlanta, Georgia 30322, and
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91
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Liu Y, Dore J, Chen X. Calcium influx through L-type channels generates protein kinase M to induce burst firing of dopamine cells in the rat ventral tegmental area. J Biol Chem 2007; 282:8594-603. [PMID: 17237234 DOI: 10.1074/jbc.m610230200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Enhanced activity of the dopaminergic system originating in the ventral tegmental area is implicated in addictive and psychiatric disorders. Burst firing increases dopamine levels at the synapse to signal novelty and salience. We have previously reported a calcium-dependent burst firing of dopamine cells mediated by L-type channels following cholinergic stimulation; this paper describes a cellular mechanism resulting in burst firing following L-type channel activation. Calcium influx through L-type channels following FPL 64176 or (S)-(-)-Bay K8644 induced burst firing independent of dopamine, glutamate, or calcium from the internal stores. Burst firing induced as such was completely blocked by the substrate site protein kinase C (PKC) inhibitor chelerythrine but not by the diacylglycerol site inhibitor calphostin C. Western blotting analysis showed that FPL 64176 and (S)-(-)-Bay K8644 increased the cleavage of PKC to generate protein kinase M (PKM) and the specific calpain inhibitor MDL28170 blocked this increase. Prevention of PKM production by inhibiting calpain or depleting PKC blocked burst firing induction whereas direct loading of purified PKM into cells induced burst firing. Activation of the N-methyl-D-aspartic acid type glutamate or cholinergic receptors known to induce burst firing increased PKM expression. These results indicate that calcium influx through L-type channels activates a calcium-dependent protease that cleaves PKC to generate constitutively active and labile PKM resulting in burst firing of dopamine cells, a pathway that is involved in glutamatergic or cholinergic modulation of the central dopamine system.
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Affiliation(s)
- Yudan Liu
- Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3V6, Canada
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92
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Voltage-gated calcium channels, calcium signaling, and channelopathies. CALCIUM - A MATTER OF LIFE OR DEATH 2007. [DOI: 10.1016/s0167-7306(06)41005-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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93
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Grueter CE, Colbran RJ, Anderson ME. CaMKII, an emerging molecular driver for calcium homeostasis, arrhythmias, and cardiac dysfunction. J Mol Med (Berl) 2006; 85:5-14. [PMID: 17119905 DOI: 10.1007/s00109-006-0125-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Revised: 10/04/2006] [Accepted: 10/10/2006] [Indexed: 01/11/2023]
Abstract
Maintenance of cytoplasmic calcium homeostasis is critical for all cells. An exciting field has emerged in elucidating the multiple roles that Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) plays in regulating Ca(2+) cycling in normal cardiac myocytes and in pathophysiological states. Moreover, CaMKII was recently identified as a potential drug target in cardiac disease. This work has given us a closer view of the complexity and therapeutic possibilities of CaMKII regulation of Ca(2+) signaling in cardiac myocytes.
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Affiliation(s)
- Chad E Grueter
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA
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