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Densin-180 Controls the Trafficking and Signaling of L-Type Voltage-Gated Ca v1.2 Ca 2+ Channels at Excitatory Synapses. J Neurosci 2017; 37:4679-4691. [PMID: 28363979 DOI: 10.1523/jneurosci.2583-16.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 03/23/2017] [Accepted: 03/27/2017] [Indexed: 11/21/2022] Open
Abstract
Voltage-gated Cav1.2 and Cav1.3 (L-type) Ca2+ channels regulate neuronal excitability, synaptic plasticity, and learning and memory. Densin-180 (densin) is an excitatory synaptic protein that promotes Ca2+-dependent facilitation of voltage-gated Cav1.3 Ca2+ channels in transfected cells. Mice lacking densin (densin KO) exhibit defects in synaptic plasticity, spatial memory, and increased anxiety-related behaviors-phenotypes that more closely match those in mice lacking Cav1.2 than Cav1.3. Therefore, we investigated the functional impact of densin on Cav1.2. We report that densin is an essential regulator of Cav1.2 in neurons, but has distinct modulatory effects compared with its regulation of Cav1.3. Densin binds to the N-terminal domain of Cav1.2, but not that of Cav1.3, and increases Cav1.2 currents in transfected cells and in neurons. In transfected cells, densin accelerates the forward trafficking of Cav1.2 channels without affecting their endocytosis. Consistent with a role for densin in increasing the number of postsynaptic Cav1.2 channels, overexpression of densin increases the clustering of Cav1.2 in dendrites of hippocampal neurons in culture. Compared with wild-type mice, the cell surface levels of Cav1.2 in the brain, as well as Cav1.2 current density and signaling to the nucleus, are reduced in neurons from densin KO mice. We conclude that densin is an essential regulator of neuronal Cav1 channels and ensures efficient Cav1.2 Ca2+ signaling at excitatory synapses.SIGNIFICANCE STATEMENT The number and localization of voltage-gated Cav Ca2+ channels are crucial determinants of neuronal excitability and synaptic transmission. We report that the protein densin-180 is highly enriched at excitatory synapses in the brain and enhances the cell surface trafficking and postsynaptic localization of Cav1.2 L-type Ca2+ channels in neurons. This interaction promotes coupling of Cav1.2 channels to activity-dependent gene transcription. Our results reveal a mechanism that may contribute to the roles of Cav1.2 in regulating cognition and mood.
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52
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Nystoriak MA, Nieves-Cintrón M, Patriarchi T, Buonarati OR, Prada MP, Morotti S, Grandi E, Fernandes JDS, Forbush K, Hofmann F, Sasse KC, Scott JD, Ward SM, Hell JW, Navedo MF. Ser1928 phosphorylation by PKA stimulates the L-type Ca2+ channel CaV1.2 and vasoconstriction during acute hyperglycemia and diabetes. Sci Signal 2017; 10:10/463/eaaf9647. [PMID: 28119464 DOI: 10.1126/scisignal.aaf9647] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Hypercontractility of arterial myocytes and enhanced vascular tone during diabetes are, in part, attributed to the effects of increased glucose (hyperglycemia) on L-type CaV1.2 channels. In murine arterial myocytes, kinase-dependent mechanisms mediate the increase in CaV1.2 activity in response to increased extracellular glucose. We identified a subpopulation of the CaV1.2 channel pore-forming subunit (α1C) within nanometer proximity of protein kinase A (PKA) at the sarcolemma of murine and human arterial myocytes. This arrangement depended upon scaffolding of PKA by an A-kinase anchoring protein 150 (AKAP150) in mice. Glucose-mediated increases in CaV1.2 channel activity were associated with PKA activity, leading to α1C phosphorylation at Ser1928 Compared to arteries from low-fat diet (LFD)-fed mice and nondiabetic patients, arteries from high-fat diet (HFD)-fed mice and from diabetic patients had increased Ser1928 phosphorylation and CaV1.2 activity. Arterial myocytes and arteries from mice lacking AKAP150 or expressing mutant AKAP150 unable to bind PKA did not exhibit increased Ser1928 phosphorylation and CaV1.2 current density in response to increased glucose or to HFD. Consistent with a functional role for Ser1928 phosphorylation, arterial myocytes and arteries from knockin mice expressing a CaV1.2 with Ser1928 mutated to alanine (S1928A) lacked glucose-mediated increases in CaV1.2 activity and vasoconstriction. Furthermore, the HFD-induced increases in CaV1.2 current density and myogenic tone were prevented in S1928A knockin mice. These findings reveal an essential role for α1C phosphorylation at Ser1928 in stimulating CaV1.2 channel activity and vasoconstriction by AKAP-targeted PKA upon exposure to increased glucose and in diabetes.
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Affiliation(s)
- Matthew A Nystoriak
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | | | - Tommaso Patriarchi
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Olivia R Buonarati
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Maria Paz Prada
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Stefano Morotti
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | | | - Katherine Forbush
- Howard Hughes Medical Institute and Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Franz Hofmann
- Department of Pharmacology and Toxicology, Technical University of Munich, Munich D80802, Germany
| | | | - John D Scott
- Howard Hughes Medical Institute and Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada, Reno, NV 89557, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA.
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53
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Qian H, Patriarchi T, Price JL, Matt L, Lee B, Nieves-Cintrón M, Buonarati OR, Chowdhury D, Nanou E, Nystoriak MA, Catterall WA, Poomvanicha M, Hofmann F, Navedo MF, Hell JW. Phosphorylation of Ser1928 mediates the enhanced activity of the L-type Ca2+ channel Cav1.2 by the β2-adrenergic receptor in neurons. Sci Signal 2017; 10:10/463/eaaf9659. [PMID: 28119465 DOI: 10.1126/scisignal.aaf9659] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The L-type Ca2+ channel Cav1.2 controls multiple functions throughout the body including heart rate and neuronal excitability. It is a key mediator of fight-or-flight stress responses triggered by a signaling pathway involving β-adrenergic receptors (βARs), cyclic adenosine monophosphate (cAMP), and protein kinase A (PKA). PKA readily phosphorylates Ser1928 in Cav1.2 in vitro and in vivo, including in rodents and humans. However, S1928A knock-in (KI) mice have normal PKA-mediated L-type channel regulation in the heart, indicating that Ser1928 is not required for regulation of cardiac Cav1.2 by PKA in this tissue. We report that augmentation of L-type currents by PKA in neurons was absent in S1928A KI mice. Furthermore, S1928A KI mice failed to induce long-term potentiation in response to prolonged theta-tetanus (PTT-LTP), a form of synaptic plasticity that requires Cav1.2 and enhancement of its activity by the β2-adrenergic receptor (β2AR)-cAMP-PKA cascade. Thus, there is an unexpected dichotomy in the control of Cav1.2 by PKA in cardiomyocytes and hippocampal neurons.
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Affiliation(s)
- Hai Qian
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Tommaso Patriarchi
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
| | - Jennifer L Price
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
| | - Lucas Matt
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
| | - Boram Lee
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
| | | | - Olivia R Buonarati
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
| | | | - Evanthia Nanou
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280, USA
| | - Matthew A Nystoriak
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
| | - William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280, USA
| | - Montatip Poomvanicha
- Department of Pharmacology and Toxicology, Technical University of Munich, D-80802 Munich, Germany
| | - Franz Hofmann
- Department of Pharmacology and Toxicology, Technical University of Munich, D-80802 Munich, Germany
| | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA.
| | - Johannes W Hell
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242-1109, USA. .,Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
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54
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Piirainen H, Taura J, Kursula P, Ciruela F, Jaakola VP. Calcium modulates calmodulin/α-actinin 1 interaction with and agonist-dependent internalization of the adenosine A 2A receptor. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:674-686. [PMID: 28130124 DOI: 10.1016/j.bbamcr.2017.01.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 01/14/2017] [Accepted: 01/23/2017] [Indexed: 10/20/2022]
Abstract
Adenosine receptors are G protein-coupled receptors that sense extracellular adenosine to transmit intracellular signals. One of the four adenosine receptor subtypes, the adenosine A2A receptor (A2AR), has an exceptionally long intracellular C terminus (A2AR-ct) that mediates interactions with a large array of proteins, including calmodulin and α-actinin. Here, we aimed to ascertain the α-actinin 1/calmodulin interplay whilst binding to A2AR and the role of Ca2+ in this process. First, we studied the A2AR-α-actinin 1 interaction by means of native polyacrylamide gel electrophoresis, isothermal titration calorimetry, and surface plasmon resonance, using purified recombinant proteins. α-Actinin 1 binds the A2AR-ct through its distal calmodulin-like domain in a Ca2+-independent manner with a dissociation constant of 5-12μM, thus showing an ~100 times lower affinity compared to the A2AR-calmodulin/Ca2+ complex. Importantly, calmodulin displaced α-actinin 1 from the A2AR-ct in a Ca2+-dependent fashion, disrupting the A2AR-α-actinin 1 complex. Finally, we assessed the impact of Ca2+ on A2AR internalization in living cells, a function operated by the A2AR-α-actinin 1 complex. Interestingly, while Ca2+ influx did not affect constitutive A2AR endocytosis, it abolished agonist-dependent internalization. In addition, we demonstrated that the A2AR/α-actinin interaction plays a pivotal role in receptor internalization and function. Overall, our results suggest that the interplay of A2AR with calmodulin and α-actinin 1 is fine-tuned by Ca2+, a fact that might power agonist-mediated receptor internalization and function.
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Affiliation(s)
- Henni Piirainen
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Finland
| | - Jaume Taura
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, Spain; Institut de Neurociències, Universitat de Barcelona, Spain
| | - Petri Kursula
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Finland; Department of Biomedicine, University of Bergen, Norway
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, Spain; Institut de Neurociències, Universitat de Barcelona, Spain.
| | - Veli-Pekka Jaakola
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Finland.
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55
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Cazade M, Bidaud I, Lory P, Chemin J. Activity-dependent regulation of T-type calcium channels by submembrane calcium ions. eLife 2017; 6. [PMID: 28109159 PMCID: PMC5308894 DOI: 10.7554/elife.22331] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 01/20/2017] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated Ca2+ channels are involved in numerous physiological functions and various mechanisms finely tune their activity, including the Ca2+ ion itself. This is well exemplified by the Ca2+-dependent inactivation of L-type Ca2+ channels, whose alteration contributes to the dramatic disease Timothy Syndrome. For T-type Ca2+ channels, a long-held view is that they are not regulated by intracellular Ca2+. Here we challenge this notion by using dedicated electrophysiological protocols on both native and expressed T-type Ca2+ channels. We demonstrate that a rise in submembrane Ca2+ induces a large decrease in T-type current amplitude due to a hyperpolarizing shift in the steady-state inactivation. Activation of most representative Ca2+-permeable ionotropic receptors similarly regulate T-type current properties. Altogether, our data clearly establish that Ca2+ entry exerts a feedback control on T-type channel activity, by modulating the channel availability, a mechanism that critically links cellular properties of T-type Ca2+ channels to their physiological roles. DOI:http://dx.doi.org/10.7554/eLife.22331.001 Neurons, muscle cells and many other types of cells use electrical signals to exchange information and coordinate their behavior. Proteins known as calcium channels sit in the membrane that surrounds the cell and can generate electrical signals by allowing calcium ions to cross the membrane and enter the cell during electrical activities. Although calcium ions are needed to generate these electrical signals, and for many other processes in cells, if the levels of calcium ions inside cells become too high they can be harmful and cause disease. Cells have a “feedback” mechanism that prevents calcium ion levels from becoming too high. This mechanism relies on the calcium ions that are already in the cell being able to close the calcium channels. This feedback mechanism has been extensively studied in two types of calcium channel, but it is not known whether a third group of channels – known as Cav3 channels – are also regulated in this way. Cav3 channels are important in electrical signaling in neurons and have been linked with epilepsy, chronic pain and various other conditions in humans. Cazade et al. investigated whether calcium ions can regulate the activity of human Cav3 channels. The experiments show that these channels are indeed regulated by calcium ions, but using a distinct mechanism to other types of calcium channels. For the Cav3 channels, calcium ions alter the gating properties of the channels so that they are less easily activated . As a result, fewer Cav3 channels are “available” to provide calcium ions with a route into the cell. The next steps following on from this work will be to identify the molecular mechanisms underlying this new feedback mechanism. Another challenge will be to find out what role this calcium ion-driven feedback plays in neurological disorders that are linked with altered Cav3 channel activity. DOI:http://dx.doi.org/10.7554/eLife.22331.002
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Affiliation(s)
- Magali Cazade
- IGF, CNRS, INSERM, University of Montpellier, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics', Montpellier, France
| | - Isabelle Bidaud
- IGF, CNRS, INSERM, University of Montpellier, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics', Montpellier, France
| | - Philippe Lory
- IGF, CNRS, INSERM, University of Montpellier, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics', Montpellier, France
| | - Jean Chemin
- IGF, CNRS, INSERM, University of Montpellier, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics', Montpellier, France
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56
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Ben-Johny M, Yue DN, Yue DT. Detecting stoichiometry of macromolecular complexes in live cells using FRET. Nat Commun 2016; 7:13709. [PMID: 27922011 PMCID: PMC5150656 DOI: 10.1038/ncomms13709] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 10/25/2016] [Indexed: 11/10/2022] Open
Abstract
The stoichiometry of macromolecular interactions is fundamental to cellular signalling yet challenging to detect from living cells. Fluorescence resonance energy transfer (FRET) is a powerful phenomenon for characterizing close-range interactions whereby a donor fluorophore transfers energy to a closely juxtaposed acceptor. Recognizing that FRET measured from the acceptor's perspective reports a related but distinct quantity versus the donor, we utilize the ratiometric comparison of the two to obtain the stoichiometry of a complex. Applying this principle to the long-standing controversy of calmodulin binding to ion channels, we find a surprising Ca2+-induced switch in calmodulin stoichiometry with Ca2+ channels—one calmodulin binds at basal cytosolic Ca2+ levels while two calmodulins interact following Ca2+ elevation. This feature is curiously absent for the related Na channels, also potently regulated by calmodulin. Overall, our assay adds to a burgeoning toolkit to pursue quantitative biochemistry of dynamic signalling complexes in living cells. Measuring the in vivo stoichiometry of protein-protein interactions is challenging. Here the authors take a FRET-based approach, quantifying stoichiometry based on ratiometric comparison of donor and acceptor fluorescence, and apply their method to report on a Ca2+-induced switch in calmodulin binding to Ca2+ ion channels.
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Affiliation(s)
- Manu Ben-Johny
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - Daniel N Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
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57
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Moreno CM, Dixon RE, Tajada S, Yuan C, Opitz-Araya X, Binder MD, Santana LF. Ca(2+) entry into neurons is facilitated by cooperative gating of clustered CaV1.3 channels. eLife 2016; 5. [PMID: 27187148 PMCID: PMC4869912 DOI: 10.7554/elife.15744] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 04/09/2016] [Indexed: 11/13/2022] Open
Abstract
CaV1.3 channels regulate excitability in many neurons. As is the case for all voltage-gated channels, it is widely assumed that individual CaV1.3 channels behave independently with respect to voltage-activation, open probability, and facilitation. Here, we report the results of super-resolution imaging, optogenetic, and electrophysiological measurements that refute this long-held view. We found that the short channel isoform (CaV1.3S), but not the long (CaV1.3L), associates in functional clusters of two or more channels that open cooperatively, facilitating Ca(2+) influx. CaV1.3S channels are coupled via a C-terminus-to-C-terminus interaction that requires binding of the incoming Ca(2+) to calmodulin (CaM) and subsequent binding of CaM to the pre-IQ domain of the channels. Physically-coupled channels facilitate Ca(2+) currents as a consequence of their higher open probabilities, leading to increased firing rates in rat hippocampal neurons. We propose that cooperative gating of CaV1.3S channels represents a mechanism for the regulation of Ca(2+) signaling and electrical activity.
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Affiliation(s)
- Claudia M Moreno
- Department of Physiology and Membrane Biology, University of California, Davis, United States
| | - Rose E Dixon
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Sendoa Tajada
- Department of Physiology and Membrane Biology, University of California, Davis, United States
| | - Can Yuan
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Ximena Opitz-Araya
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Marc D Binder
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Luis F Santana
- Department of Physiology and Membrane Biology, University of California, Davis, United States
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58
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Myoscape controls cardiac calcium cycling and contractility via regulation of L-type calcium channel surface expression. Nat Commun 2016; 7:11317. [PMID: 27122098 DOI: 10.1315/11317] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 03/13/2016] [Indexed: 01/29/2023] Open
Abstract
Calcium signalling plays a critical role in the pathogenesis of heart failure. Here we describe a cardiac protein named Myoscape/FAM40B/STRIP2, which directly interacts with the L-type calcium channel. Knockdown of Myoscape in cardiomyocytes decreases calcium transients associated with smaller Ca(2+) amplitudes and a lower diastolic Ca(2+) content. Likewise, L-type calcium channel currents are significantly diminished on Myoscape ablation, and downregulation of Myoscape significantly reduces contractility of cardiomyocytes. Conversely, overexpression of Myoscape increases global Ca(2+) transients and enhances L-type Ca(2+) channel currents, and is sufficient to restore decreased currents in failing cardiomyocytes. In vivo, both Myoscape-depleted morphant zebrafish and Myoscape knockout (KO) mice display impairment of cardiac function progressing to advanced heart failure. Mechanistically, Myoscape-deficient mice show reduced L-type Ca(2+)currents, cell capacity and calcium current densities as a result of diminished LTCC surface expression. Finally, Myoscape expression is reduced in hearts from patients suffering of terminal heart failure, implying a role in human disease.
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59
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Myoscape controls cardiac calcium cycling and contractility via regulation of L-type calcium channel surface expression. Nat Commun 2016. [PMID: 27122098 PMCID: PMC5438100 DOI: 10.1038/ncomms11317] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Calcium signalling plays a critical role in the pathogenesis of heart failure. Here we describe a cardiac protein named Myoscape/FAM40B/STRIP2, which directly interacts with the L-type calcium channel. Knockdown of Myoscape in cardiomyocytes decreases calcium transients associated with smaller Ca2+ amplitudes and a lower diastolic Ca2+ content. Likewise, L-type calcium channel currents are significantly diminished on Myoscape ablation, and downregulation of Myoscape significantly reduces contractility of cardiomyocytes. Conversely, overexpression of Myoscape increases global Ca2+ transients and enhances L-type Ca2+ channel currents, and is sufficient to restore decreased currents in failing cardiomyocytes. In vivo, both Myoscape-depleted morphant zebrafish and Myoscape knockout (KO) mice display impairment of cardiac function progressing to advanced heart failure. Mechanistically, Myoscape-deficient mice show reduced L-type Ca2+currents, cell capacity and calcium current densities as a result of diminished LTCC surface expression. Finally, Myoscape expression is reduced in hearts from patients suffering of terminal heart failure, implying a role in human disease. Heart failure is a major public health issue but due to our poor disease understanding the current therapies are symptomatic. Here the authors identify Myoscape as a novel cardiac protein regulating membrane localization of the L-type calcium channel and heart's contractile force, thus promising new therapeutic avenues for heart failure.
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60
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Perez JD, Rubinstein ND, Dulac C. New Perspectives on Genomic Imprinting, an Essential and Multifaceted Mode of Epigenetic Control in the Developing and Adult Brain. Annu Rev Neurosci 2016; 39:347-84. [PMID: 27145912 DOI: 10.1146/annurev-neuro-061010-113708] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Mammalian evolution entailed multiple innovations in gene regulation, including the emergence of genomic imprinting, an epigenetic regulation leading to the preferential expression of a gene from its maternal or paternal allele. Genomic imprinting is highly prevalent in the brain, yet, until recently, its central roles in neural processes have not been fully appreciated. Here, we provide a comprehensive survey of adult and developmental brain functions influenced by imprinted genes, from neural development and wiring to synaptic function and plasticity, energy balance, social behaviors, emotions, and cognition. We further review the widespread identification of parental biases alongside monoallelic expression in brain tissues, discuss their potential roles in dosage regulation of key neural pathways, and suggest possible mechanisms underlying the dynamic regulation of imprinting in the brain. This review should help provide a better understanding of the significance of genomic imprinting in the normal and pathological brain of mammals including humans.
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Affiliation(s)
- Julio D Perez
- Department of Molecular and Cellular Biology, Harvard University, Howard Hughes Medical Institute, Cambridge, Massachusetts 02138;
| | - Nimrod D Rubinstein
- Department of Molecular and Cellular Biology, Harvard University, Howard Hughes Medical Institute, Cambridge, Massachusetts 02138;
| | - Catherine Dulac
- Department of Molecular and Cellular Biology, Harvard University, Howard Hughes Medical Institute, Cambridge, Massachusetts 02138;
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61
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Patriarchi T, Qian H, Di Biase V, Malik ZA, Chowdhury D, Price JL, Hammes EA, Buonarati OR, Westenbroek RE, Catterall WA, Hofmann F, Xiang YK, Murphy GG, Chen CY, Navedo MF, Hell JW. Phosphorylation of Cav1.2 on S1928 uncouples the L-type Ca2+ channel from the β2 adrenergic receptor. EMBO J 2016; 35:1330-45. [PMID: 27103070 DOI: 10.15252/embj.201593409] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 03/24/2016] [Indexed: 01/07/2023] Open
Abstract
Agonist-triggered downregulation of β-adrenergic receptors (ARs) constitutes vital negative feedback to prevent cellular overexcitation. Here, we report a novel downregulation of β2AR signaling highly specific for Cav1.2. We find that β2-AR binding to Cav1.2 residues 1923-1942 is required for β-adrenergic regulation of Cav1.2. Despite the prominence of PKA-mediated phosphorylation of Cav1.2 S1928 within the newly identified β2AR binding site, its physiological function has so far escaped identification. We show that phosphorylation of S1928 displaces the β2AR from Cav1.2 upon β-adrenergic stimulation rendering Cav1.2 refractory for several minutes from further β-adrenergic stimulation. This effect is lost in S1928A knock-in mice. Although AMPARs are clustered at postsynaptic sites like Cav1.2, β2AR association with and regulation of AMPARs do not show such dissociation. Accordingly, displacement of the β2AR from Cav1.2 is a uniquely specific desensitization mechanism of Cav1.2 regulation by highly localized β2AR/cAMP/PKA/S1928 signaling. The physiological implications of this mechanism are underscored by our finding that LTP induced by prolonged theta tetanus (PTT-LTP) depends on Cav1.2 and its regulation by channel-associated β2AR.
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Affiliation(s)
| | - Hai Qian
- Department of Pharmacology, University of Iowa, Iowa City, IA, USA
| | | | - Zulfiquar A Malik
- Department of Pharmacology, University of California, Davis, CA, USA Department of Pharmacology, University of Iowa, Iowa City, IA, USA
| | | | - Jennifer L Price
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Erik A Hammes
- Department of Pharmacology, University of California, Davis, CA, USA
| | | | | | | | - Franz Hofmann
- Department of Pharmacology and Toxicology, Technical University of Munich, Munich, Germany
| | - Yang K Xiang
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Geoffrey G Murphy
- Department of Molecular & Integrative Physiology, Molecular & Behavioral Neuroscience Institute University of Michigan, Ann Arbor, MI, USA
| | - Chao-Ye Chen
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, CA, USA Department of Pharmacology, University of Iowa, Iowa City, IA, USA
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62
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Turner M, Anderson DE, Rajan S, Hell JW, Ames JB. Chemical shift assignments of the C-terminal EF-hand domain of α-actinin-1. BIOMOLECULAR NMR ASSIGNMENTS 2016; 10:219-222. [PMID: 26861220 PMCID: PMC4789133 DOI: 10.1007/s12104-016-9670-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 02/05/2016] [Indexed: 06/05/2023]
Abstract
The regulation and localization of the neuronal voltage gated Ca(2+) channel CaV1.2 is important for synaptic plasticity associated with learning and memory. The cytoskeletal protein, α-actinin-1 is known to interact with CaV1.2 and stabilize its localization at the postsynaptic membrane. Here we report both backbone and sidechain NMR assignments for the C-terminal EF-hands (EF3 and EF4) of α-actinin-1 (residues 824-892, called ACTN_EF34) bound to the IQ-motif (residues 1644-1665) from CaV1.2 (BMRB accession no. 25902).
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Affiliation(s)
- Matthew Turner
- Department of Chemistry, University of California, Davis, Davis, CA, 95616, USA
| | - David E Anderson
- Department of Chemistry, University of California, Davis, Davis, CA, 95616, USA
| | - Sahana Rajan
- Department of Chemistry, University of California, Davis, Davis, CA, 95616, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, USA
| | - James B Ames
- Department of Chemistry, University of California, Davis, Davis, CA, 95616, USA.
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Alternative Splicing in Ca(V)2.2 Regulates Neuronal Trafficking via Adaptor Protein Complex-1 Adaptor Protein Motifs. J Neurosci 2016; 35:14636-52. [PMID: 26511252 DOI: 10.1523/jneurosci.3034-15.2015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
N-type voltage-gated calcium (Ca(V)2.2) channels are expressed in neurons and targeted to the plasma membrane of presynaptic terminals, facilitating neurotransmitter release. Here, we find that the adaptor protein complex-1 (AP-1) mediates trafficking of Ca(V)2.2 from the trans-Golgi network to the cell surface. Examination of splice variants of Ca(V)2.2, containing either exon 37a (selectively expressed in nociceptors) or 37b in the proximal C terminus, reveal that canonical AP-1 binding motifs, YxxΦ and [DE]xxxL[LI], present only in exon 37a, enhance intracellular trafficking of exon 37a-containing Ca(V)2.2 to the axons and plasma membrane of rat DRG neurons. Finally, we identify differential effects of dopamine-2 receptor (D2R) and its agonist-induced activation on trafficking of Ca(V)2.2 isoforms. D2R slowed the endocytosis of Ca(V)2.2 containing exon 37b, but not exon 37a, and activation by the agonist quinpirole reversed the effect of the D2R. Our work thus reveals key mechanisms involved in the trafficking of N-type calcium channels.
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64
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Identification of Novel Death-Associated Protein Kinase 2 Interaction Partners by Proteomic Screening Coupled with Bimolecular Fluorescence Complementation. Mol Cell Biol 2015; 36:132-43. [PMID: 26483415 DOI: 10.1128/mcb.00515-15] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 10/08/2015] [Indexed: 11/20/2022] Open
Abstract
Death-associated protein kinase 2 (DAPK2) is a Ca(2+)/calmodulin-dependent Ser/Thr kinase that possesses tumor-suppressive functions and regulates programmed cell death, autophagy, oxidative stress, hematopoiesis, and motility. As only few binding partners of DAPK2 have been determined, the molecular mechanisms governing these biological functions are largely unknown. We report the identification of 180 potential DAPK2 interaction partners by affinity purification-coupled mass spectrometry, 12 of which are known DAPK binding proteins. A small subset of established and potential binding proteins detected in this screen was further investigated by bimolecular fluorescence complementation (BiFC) assays, a method to visualize protein interactions in living cells. These experiments revealed that α-actinin-1 and 14-3-3-β are novel DAPK2 binding partners. The interaction of DAPK2 with α-actinin-1 was localized at the plasma membrane, resulting in massive membrane blebbing and reduced cellular motility, whereas the interaction of DAPK2 with 14-3-3-β was localized to the cytoplasm, with no impact on blebbing, motility, or viability. Our results therefore suggest that DAPK2 effector functions are influenced by the protein's subcellular localization and highlight the utility of combining mass spectrometry screening with bimolecular fluorescence complementation to identify and characterize novel protein-protein interactions.
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65
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Heyes S, Pratt WS, Rees E, Dahimene S, Ferron L, Owen MJ, Dolphin AC. Genetic disruption of voltage-gated calcium channels in psychiatric and neurological disorders. Prog Neurobiol 2015; 134:36-54. [PMID: 26386135 PMCID: PMC4658333 DOI: 10.1016/j.pneurobio.2015.09.002] [Citation(s) in RCA: 164] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 09/08/2015] [Accepted: 09/08/2015] [Indexed: 12/15/2022]
Abstract
Voltage-gated calcium channel classification—genes and proteins. Genetic analysis of neuropsychiatric syndromes. Calcium channel genes identified from GWA studies of psychiatric disorders. Rare mutations in calcium channel genes in psychiatric disorders. Pathophysiological sequelae of CACNA1C mutations and polymorphisms. Monogenic disorders resulting from harmful mutations in other voltage-gated calcium channel genes. Changes in calcium channel gene expression in disease. Involvement of voltage-gated calcium channels in early brain development.
This review summarises genetic studies in which calcium channel genes have been connected to the spectrum of neuropsychiatric syndromes, from bipolar disorder and schizophrenia to autism spectrum disorders and intellectual impairment. Among many other genes, striking numbers of the calcium channel gene superfamily have been implicated in the aetiology of these diseases by various DNA analysis techniques. We will discuss how these relate to the known monogenic disorders associated with point mutations in calcium channels. We will then examine the functional evidence for a causative link between these mutations or single nucleotide polymorphisms and the disease processes. A major challenge for the future will be to translate the expanding psychiatric genetic findings into altered physiological function, involvement in the wider pathology of the diseases, and what potential that provides for personalised and stratified treatment options for patients.
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Affiliation(s)
- Samuel Heyes
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Wendy S Pratt
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Elliott Rees
- Medical Research Council Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Shehrazade Dahimene
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Laurent Ferron
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Michael J Owen
- Medical Research Council Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK.
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66
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Hou W, Izadi M, Nemitz S, Haag N, Kessels MM, Qualmann B. The Actin Nucleator Cobl Is Controlled by Calcium and Calmodulin. PLoS Biol 2015; 13:e1002233. [PMID: 26334624 PMCID: PMC4559358 DOI: 10.1371/journal.pbio.1002233] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 07/23/2015] [Indexed: 01/10/2023] Open
Abstract
Actin nucleation triggers the formation of new actin filaments and has the power to shape cells but requires tight control in order to bring about proper morphologies. The regulation of the members of the novel class of WASP Homology 2 (WH2) domain-based actin nucleators, however, thus far has largely remained elusive. Our study reveals signal cascades and mechanisms regulating Cordon-Bleu (Cobl). Cobl plays some, albeit not fully understood, role in early arborization of neurons and nucleates actin by a mechanism that requires a combination of all three of its actin monomer–binding WH2 domains. Our experiments reveal that Cobl is regulated by Ca2+ and multiple, direct associations of the Ca2+ sensor Calmodulin (CaM). Overexpression analyses and rescue experiments of Cobl loss-of-function phenotypes with Cobl mutants in primary neurons and in tissue slices demonstrated the importance of CaM binding for Cobl’s functions. Cobl-induced dendritic branch initiation was preceded by Ca2+ signals and coincided with local F-actin and CaM accumulations. CaM inhibitor studies showed that Cobl-mediated branching is strictly dependent on CaM activity. Mechanistic studies revealed that Ca2+/CaM modulates Cobl’s actin binding properties and furthermore promotes Cobl’s previously identified interactions with the membrane-shaping F-BAR protein syndapin I, which accumulated with Cobl at nascent dendritic protrusion sites. The findings of our study demonstrate a direct regulation of an actin nucleator by Ca2+/CaM and reveal that the Ca2+/CaM-controlled molecular mechanisms we discovered are crucial for Cobl’s cellular functions. By unveiling the means of Cobl regulation and the mechanisms, by which Ca2+/CaM signals directly converge on a cellular effector promoting actin filament formation, our work furthermore sheds light on how local Ca2+ signals steer and power branch initiation during early arborization of nerve cells—a key process in neuronal network formation. The calcium sensor calmodulin directly regulates the actin filament-promoting factor Cobl to help shape the complex architecture of neurons underlying neuronal network formation. The organization and the formation of new actin filaments by polymerization of actin monomers has the power to shape cells. The rate-limiting step in actin polymerization is “nucleation”—a process during which the first actin monomers are assembled with the help of actin nucleators. This nucleation step requires tight temporal and spatial control in order to achieve proper cell morphologies. Here, we analyse signaling cascades and mechanisms regulating the actin nucleator Cobl, which is crucial for the formation of dendritic arbors of nerve cells—a key process in neuronal network formation. We show that the calcium (Ca2+)-binding signaling component calmodulin (CaM) binds to Cobl and regulates its functions. Using 3-D time-lapse analyses of developing neurons, we visualized how Cobl works. We observed local accumulation of CaM, Cobl, actin, and syndapin I—a membrane-shaping protein—at dendritic branch initiation sites. We find that Ca2+/CaM modulates Cobl’s actin-binding properties and promotes its interactions with syndapin I, which then serves as a membrane anchor for Cobl. In summary, we i) show a direct regulation of the actin nucleator Cobl by Ca2+/CaM, ii) demonstrate that the molecular mechanisms we discovered are crucial for shaping nerve cells, and iii) underscore how local Ca2+ signals steer and power branch initiation during early arborization of neurons.
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Affiliation(s)
- Wenya Hou
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University Jena, Jena, Germany
| | - Maryam Izadi
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University Jena, Jena, Germany
| | - Sabine Nemitz
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University Jena, Jena, Germany
| | - Natja Haag
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University Jena, Jena, Germany
| | - Michael M. Kessels
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University Jena, Jena, Germany
- * E-mail: (BQ); (MMK)
| | - Britta Qualmann
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University Jena, Jena, Germany
- * E-mail: (BQ); (MMK)
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67
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Kaur G, Pinggera A, Ortner NJ, Lieb A, Sinnegger-Brauns MJ, Yarov-Yarovoy V, Obermair GJ, Flucher BE, Striessnig J. A Polybasic Plasma Membrane Binding Motif in the I-II Linker Stabilizes Voltage-gated CaV1.2 Calcium Channel Function. J Biol Chem 2015; 290:21086-21100. [PMID: 26100638 PMCID: PMC4543666 DOI: 10.1074/jbc.m115.645671] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Indexed: 12/27/2022] Open
Abstract
L-type voltage-gated Ca(2+) channels (LTCCs) regulate many physiological functions like muscle contraction, hormone secretion, gene expression, and neuronal excitability. Their activity is strictly controlled by various molecular mechanisms. The pore-forming α1-subunit comprises four repeated domains (I-IV), each connected via an intracellular linker. Here we identified a polybasic plasma membrane binding motif, consisting of four arginines, within the I-II linker of all LTCCs. The primary structure of this motif is similar to polybasic clusters known to interact with polyphosphoinositides identified in other ion channels. We used de novo molecular modeling to predict the conformation of this polybasic motif, immunofluorescence microscopy and live cell imaging to investigate the interaction with the plasma membrane, and electrophysiology to study its role for Cav1.2 channel function. According to our models, this polybasic motif of the I-II linker forms a straight α-helix, with the positive charges facing the lipid phosphates of the inner leaflet of the plasma membrane. Membrane binding of the I-II linker could be reversed after phospholipase C activation, causing polyphosphoinositide breakdown, and was accelerated by elevated intracellular Ca(2+) levels. This indicates the involvement of negatively charged phospholipids in the plasma membrane targeting of the linker. Neutralization of four arginine residues eliminated plasma membrane binding. Patch clamp recordings revealed facilitated opening of Cav1.2 channels containing these mutations, weaker inhibition by phospholipase C activation, and reduced expression of channels (as quantified by ON-gating charge) at the plasma membrane. Our data provide new evidence for a membrane binding motif within the I-II linker of LTCC α1-subunits essential for stabilizing normal Ca(2+) channel function.
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Affiliation(s)
- Gurjot Kaur
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Alexandra Pinggera
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Nadine J Ortner
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Andreas Lieb
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Martina J Sinnegger-Brauns
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, UC Davis School of Medicine, Davis, California 95616
| | - Gerald J Obermair
- Division of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Bernhard E Flucher
- Division of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Jörg Striessnig
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria.
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68
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Kalinowska M, Chávez AE, Lutzu S, Castillo PE, Bukauskas FF, Francesconi A. Actinin-4 Governs Dendritic Spine Dynamics and Promotes Their Remodeling by Metabotropic Glutamate Receptors. J Biol Chem 2015; 290:15909-20. [PMID: 25944910 DOI: 10.1074/jbc.m115.640136] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Indexed: 11/06/2022] Open
Abstract
Dendritic spines are dynamic, actin-rich protrusions in neurons that undergo remodeling during neuronal development and activity-dependent plasticity within the central nervous system. Although group 1 metabotropic glutamate receptors (mGluRs) are critical for spine remodeling under physiopathological conditions, the molecular components linking receptor activity to structural plasticity remain unknown. Here we identify a Ca(2+)-sensitive actin-binding protein, α-actinin-4, as a novel group 1 mGluR-interacting partner that orchestrates spine dynamics and morphogenesis in primary neurons. Functional silencing of α-actinin-4 abolished spine elongation and turnover stimulated by group 1 mGluRs despite intact surface receptor expression and downstream ERK1/2 signaling. This function of α-actinin-4 in spine dynamics was underscored by gain-of-function phenotypes in untreated neurons. Here α-actinin-4 induced spine head enlargement, a morphological change requiring the C-terminal domain of α-actinin-4 that binds to CaMKII, an interaction we showed to be regulated by group 1 mGluR activation. Our data provide mechanistic insights into spine remodeling by metabotropic signaling and identify α-actinin-4 as a critical effector of structural plasticity within neurons.
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Affiliation(s)
- Magdalena Kalinowska
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Andrés E Chávez
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Stefano Lutzu
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Pablo E Castillo
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Feliksas F Bukauskas
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Anna Francesconi
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
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69
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Zhang X, Li F, Guo L, Hei H, Tian L, Peng W, Cai H. Forskolin Regulates L-Type Calcium Channel through Interaction between Actinin 4 and β3 Subunit in Osteoblasts. PLoS One 2015; 10:e0124274. [PMID: 25902045 PMCID: PMC4406748 DOI: 10.1371/journal.pone.0124274] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 03/11/2015] [Indexed: 12/23/2022] Open
Abstract
Voltage-dependent L-type calcium channels that permit cellular calcium influx are essential in calcium-mediated modulation of cellular signaling. Although the regulation of voltage-dependent L-type calcium channels is linked to many factors including cAMP-dependent protein kinase A (PKA) activity and actin cytoskeleton, little is known about the detailed mechanisms underlying the regulation in osteoblasts. Our present study investigated the modulation of L-type calcium channel activities through the effects of forskolin on actin reorganization and on its functional interaction with actin binding protein actinin 4. The results showed that forskolin did not significantly affect the trafficking of pore forming α1c subunit and its interaction with actin binding protein actinin 4, whereas it significantly increased the expression of β3 subunit and its interaction with actinin 4 in osteoblast cells as assessed by co-immunoprecipitation, pull-down assay, and immunostaining. Further mapping showed that the ABD and EF domains of actinin 4 were interaction sites. This interaction is independent of PKA phosphorylation. Knockdown of actinin 4 significantly decreased the activities of L-type calcium channels. Our study revealed a new aspect of the mechanisms by which the forskolin activation of adenylyl cyclase - cAMP cascade regulates the L-type calcium channel in osteoblast cells, besides the PKA mediated phosphorylation of the channel subunits. These data provide insight into the important role of interconnection among adenylyl cyclase, cAMP, PKA, the actin cytoskeleton, and the channel proteins in the regulation of voltage-dependent L-type calcium channels in osteoblast cells.
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Affiliation(s)
- Xuemei Zhang
- Department of Pharmacology, School of Pharmacy, Fudan University, 826 Zhangheng Road, Pudong New District, Shanghai, 201203, China
- * E-mail: (XZ); (WP)
| | - Fangping Li
- Department of Pharmacy, Jing’an District Center Hospital of Shanghai (Huashan Hospital, Fudan University, Jing’an Branch), 259 Xikang Road, Shanghai, 200040, China
| | - Lin Guo
- Department of Pharmacology, School of Pharmacy, Fudan University, 826 Zhangheng Road, Pudong New District, Shanghai, 201203, China
| | - Hongya Hei
- Department of Pharmacology, School of Pharmacy, Fudan University, 826 Zhangheng Road, Pudong New District, Shanghai, 201203, China
| | - Lulu Tian
- Department of Pharmacology, School of Pharmacy, Fudan University, 826 Zhangheng Road, Pudong New District, Shanghai, 201203, China
| | - Wen Peng
- Department of Nephrology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine,164 Lanxi Road, Shanghai, 200062, PR China
- * E-mail: (XZ); (WP)
| | - Hui Cai
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, 30322, United States of America
- Renal Section, Atlanta Veteran Administration Medical Center, Decatur, GA, 30033, United States of America
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70
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Sosial E, Nussinovitch I. Multiple Ca2+ channel-dependent components in growth hormone secretion from rat anterior pituitary somatotrophs. J Neuroendocrinol 2015; 27:166-76. [PMID: 25442738 DOI: 10.1111/jne.12240] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 11/25/2014] [Accepted: 11/25/2014] [Indexed: 12/22/2022]
Abstract
The involvement of L-type Ca(2+) channels in both 'basal' and 'stimulated' growth hormone (GH) secretion is well established; however, knowledge regarding the involvement of non-L-type Ca(2+) channels is lacking. We investigated whether non-L-type Ca(2+) channels regulate GH secretion from anterior pituitary (AP) cells. To this end, GH secretion was monitored from dissociated AP cells, which were incubated for 15 min with 2 mm K(+) ('basal' secretion) or 60 mm K(+) ('stimulated' secretion). The role of non-L-type Ca(2+) influx was investigated using specific channel blockers, including ω-agatoxin-IVA, ω-conotoxin GVIA or SNX-482, to block P/Q-, N- or R-type Ca(2+) channels, respectively. Our results demonstrate that P/Q-, N- and R-type Ca(2+) channels contributed 21.2 ± 1.9%, 20.2 ± 7.6% and 11.4 ± 1.8%, respectively, to 'basal' GH secretion and 18.3 ± 1.0%, 24.4 ± 5.4% and 14.2 ± 4.8%, respectively, to 'stimulated' GH secretion. After treatment with a 'cocktail' that comprised the previously described non-L-type blockers, non-L-type Ca(2+) channels contributed 50.9 ± 0.4% and 45.5 ± 2.0% to 'basal' and 'stimulated' GH secretion, respectively. Similarly, based on the effects of nifedipine (10 μM), L-type Ca(2+) channels contributed 34.2 ± 3.7% and 54.7 ± 4.1% to 'basal' and 'stimulated' GH secretion, respectively. Interestingly, the relative contributions of L-type/non-L-type Ca(2+) channels to 'stimulated' GH secretion were well correlated with the relative contributions of L-type/non-L-type Ca(2+) channels to voltage-gated Ca(2+) influx in AP cells. Finally, we demonstrated that compartmentalisation of Ca(2+) channels is important for GH secretion. Lipid raft disruption (methyl-β-cyclodextrin, 10 mm) abrogated the compartmentalisation of Ca(2+) channels and substantially reduced 'basal' and 'stimulated' GH secretion by 43.2 ± 3.4% and 58.4 ± 4.0%, respectively. In summary, we have demonstrated that multiple Ca(2+) channel-dependent pathways regulate GH secretion. The proper function of these pathways depends on their compartmentalisation within AP cell membranes.
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Affiliation(s)
- E Sosial
- Department of Medical Neurobiology, Institute for Medical Research-Israel-Canada, The Hebrew University Faculty of Medicine, Jerusalem, Israel
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71
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Mihalikova A, Baliova M, Jursky F. Calcium dependent interaction of calmodulin with the GlyT1 C-terminus. Neurochem Res 2014; 39:2225-33. [PMID: 25168305 DOI: 10.1007/s11064-014-1424-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 08/19/2014] [Accepted: 08/21/2014] [Indexed: 11/25/2022]
Abstract
The cytoplasmic regions of neurotransmitter transporters play an important role in their trafficking. This process is, to a high extent, tuned by calcium and calcium binding proteins, but the exact molecular connection are still not fully understood. In this work we found that the C-terminal region of the mouse glycine transporter GlyT1b is able to specifically interact with calmodulin in the presence of calcium. We found that several GlyT1 C-terminal mutations, including those in the ER retention signal, either eliminate or increase calmodulin interaction in vitro. In tissue-culture-expressed GlyT1 at least two of these mutations altered the sensitivity of GlyT1 surface expression and glycine uptake to calmodulin antagonists. These results suggest the possible involvement of calmodulin or calmodulin-like interactions in the regulation of GlyT1C-mediated transporter trafficking.
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Affiliation(s)
- Andrea Mihalikova
- Laboratory of Neurobiology, Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska cesta 21, 845 51, Bratislava, Slovakia
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72
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Hodges JL, Vilchez SM, Asmussen H, Whitmore LA, Horwitz AR. α-Actinin-2 mediates spine morphology and assembly of the post-synaptic density in hippocampal neurons. PLoS One 2014; 9:e101770. [PMID: 25007055 PMCID: PMC4090192 DOI: 10.1371/journal.pone.0101770] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 06/10/2014] [Indexed: 11/18/2022] Open
Abstract
Dendritic spines are micron-sized protrusions that constitute the primary post-synaptic sites of excitatory neurotransmission in the brain. Spines mature from a filopodia-like protrusion into a mushroom-shaped morphology with a post-synaptic density (PSD) at its tip. Modulation of the actin cytoskeleton drives these morphological changes as well as the spine dynamics that underlie learning and memory. Several PSD molecules respond to glutamate receptor activation and relay signals to the underlying actin cytoskeleton to regulate the structural changes in spine and PSD morphology. α-Actinin-2 is an actin filament cross-linker, which localizes to dendritic spines, enriched within the post-synaptic density, and implicated in actin organization. We show that loss of α-actinin-2 in rat hippocampal neurons creates an increased density of immature, filopodia-like protrusions that fail to mature into a mushroom-shaped spine during development. α-Actinin-2 knockdown also prevents the recruitment and stabilization of the PSD in the spine, resulting in failure of synapse formation, and an inability to structurally respond to chemical stimulation of the N-methyl-D-aspartate (NMDA)-type glutamate receptor. The Ca2+-insensitive EF-hand motif in α-actinin-2 is necessary for the molecule's function in regulating spine morphology and PSD assembly, since exchanging it for the similar but Ca2+-sensitive domain from α-actinin-4, another α-actinin isoform, inhibits its function. Furthermore, when the Ca2+-insensitive domain from α-actinin-2 is inserted into α-actinin-4 and expressed in neurons, it creates mature spines. These observations support a model whereby α-actinin-2, partially through its Ca2+-insensitive EF-hand motif, nucleates PSD formation via F-actin organization and modulates spine maturation to mediate synaptogenesis.
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Affiliation(s)
- Jennifer L. Hodges
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
- * E-mail: (ARH); (JLH)
| | - Samuel Martin Vilchez
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Hannelore Asmussen
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Leanna A. Whitmore
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Alan Rick Horwitz
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
- * E-mail: (ARH); (JLH)
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73
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The Ever Changing Moods of Calmodulin: How Structural Plasticity Entails Transductional Adaptability. J Mol Biol 2014; 426:2717-35. [DOI: 10.1016/j.jmb.2014.05.016] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 05/14/2014] [Accepted: 05/16/2014] [Indexed: 11/20/2022]
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Simms BA, Zamponi GW. Neuronal voltage-gated calcium channels: structure, function, and dysfunction. Neuron 2014; 82:24-45. [PMID: 24698266 DOI: 10.1016/j.neuron.2014.03.016] [Citation(s) in RCA: 420] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Voltage-gated calcium channels are the primary mediators of depolarization-induced calcium entry into neurons. There is great diversity of calcium channel subtypes due to multiple genes that encode calcium channel α1 subunits, coassembly with a variety of ancillary calcium channel subunits, and alternative splicing. This allows these channels to fulfill highly specialized roles in specific neuronal subtypes and at particular subcellular loci. While calcium channels are of critical importance to brain function, their inappropriate expression or dysfunction gives rise to a variety of neurological disorders, including, pain, epilepsy, migraine, and ataxia. This Review discusses salient aspects of voltage-gated calcium channel function, physiology, and pathophysiology.
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Affiliation(s)
- Brett A Simms
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada.
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75
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Abstract
α-Actinins are a major class of actin filament cross-linking proteins expressed in virtually all cells. In muscle, actinins cross-link thin filaments from adjacent sarcomeres. In non-muscle cells, different actinin isoforms play analogous roles in cross-linking actin filaments and anchoring them to structures such as cell-cell and cell-matrix junctions. Although actinins have long been known to play roles in cytokinesis, cell adhesion and cell migration, recent studies have provided further mechanistic insights into these functions. Roles for actinins in synaptic plasticity and membrane trafficking events have emerged more recently, as has a 'non-canonical' function for actinins in transcriptional regulation in the nucleus. In the present paper we review recent advances in our understanding of these diverse cell biological functions of actinins in non-muscle cells, as well as their roles in cancer and in genetic disorders affecting platelet and kidney physiology. We also make two proposals with regard to the actinin nomenclature. First, we argue that naming actinin isoforms according to their expression patterns is problematic and we suggest a more precise nomenclature system. Secondly, we suggest that the α in α-actinin is superfluous and can be omitted.
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76
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Simms BA, Souza IA, Zamponi GW. Effect of the Brugada syndrome mutation A39V on calmodulin regulation of Cav1.2 channels. Mol Brain 2014; 7:34. [PMID: 24775099 PMCID: PMC4012176 DOI: 10.1186/1756-6606-7-34] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 04/23/2014] [Indexed: 01/22/2023] Open
Abstract
Background The L-type calcium channel Cav1.2 is important for brain and heart function. The ubiquitous calcium sensing protein calmodulin (CaM) regulates calcium dependent gating of Cav1.2 channels by reducing calcium influx, a process known as calcium-dependent inactivation (CDI). Dissecting the calcium-dependence of CaM in this process has benefited greatly from the use of mutant CaM molecules which are unable to bind calcium to their low affinity (N-lobe) and high affinity (C-lobe) binding sites. Unlike CDI, it is unknown whether CaM can modulate the activation gating of Cav1.2 channels. Results We examined a Cav1.2 point mutant in the N-terminus region of the channel (A39V) that has been previously linked to Brugada syndrome. Using mutant CaM constructs in which the N- and/or C-lobe calcium binding sites were ablated, we were able to show that this Brugada syndrome mutation disrupts N-lobe CDI of the channel. In the course of these experiments, we discovered that all mutant CaM molecules were able to alter the kinetics of channel activation even in the absence of calcium for WT-Cav1.2, but not A39V-Cav1.2 channels. Moreover, CaM mutants differentially shifted the voltage-dependence of activation for WT and A39V-Cav1.2 channels to hyperpolarized potentials. Our data therefore suggest that structural changes in CaM that arise directly from site directed mutagenesis of calcium binding domains alter activation gating of Cav1.2 channels independently of their effects on calcium binding, and that the N-terminus of the channel contributes to this CaM dependent process. Conclusions Our data indicate that caution must be exercised when interpreting the effects of CaM mutants on ion channel gating.
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Affiliation(s)
| | | | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Dr, NW, Calgary T2N 4N1, Canada.
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77
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Zhang Y, Matt L, Patriarchi T, Malik ZA, Chowdhury D, Park DK, Renieri A, Ames JB, Hell JW. Capping of the N-terminus of PSD-95 by calmodulin triggers its postsynaptic release. EMBO J 2014; 33:1341-53. [PMID: 24705785 DOI: 10.1002/embj.201488126] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Postsynaptic density protein-95 (PSD-95) is a central element of the postsynaptic architecture of glutamatergic synapses. PSD-95 mediates postsynaptic localization of AMPA receptors and NMDA receptors and plays an important role in synaptic plasticity. PSD-95 is released from postsynaptic membranes in response to Ca(2+) influx via NMDA receptors. Here, we show that Ca(2+)/calmodulin (CaM) binds at the N-terminus of PSD-95. Our NMR structure reveals that both lobes of CaM collapse onto a helical structure of PSD-95 formed at its N-terminus (residues 1-16). This N-terminal capping of PSD-95 by CaM blocks palmitoylation of C3 and C5, which is required for postsynaptic PSD-95 targeting and the binding of CDKL5, a kinase important for synapse stability. CaM forms extensive hydrophobic contacts with Y12 of PSD-95. The PSD-95 mutant Y12E strongly impairs binding to CaM and Ca(2+)-induced release of PSD-95 from the postsynaptic membrane in dendritic spines. Our data indicate that CaM binding to PSD-95 serves to block palmitoylation of PSD-95, which in turn promotes Ca(2+)-induced dissociation of PSD-95 from the postsynaptic membrane.
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Affiliation(s)
- Yonghong Zhang
- Department of Chemistry, University of California, Davis, CA, USA
| | - Lucas Matt
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Tommaso Patriarchi
- Department of Pharmacology, University of California, Davis, CA, USA Department of Medical Genetics, University of Siena, Siena, Italy
| | - Zulfiqar A Malik
- Department of Pharmacology, University of California, Davis, CA, USA
| | | | - Deborah K Park
- Department of Pharmacology, University of California, Davis, CA, USA
| | | | - James B Ames
- Department of Chemistry, University of California, Davis, CA, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, CA, USA
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78
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Hell JW. CaMKII: claiming center stage in postsynaptic function and organization. Neuron 2014; 81:249-65. [PMID: 24462093 DOI: 10.1016/j.neuron.2013.12.024] [Citation(s) in RCA: 255] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/23/2013] [Indexed: 11/16/2022]
Abstract
While CaMKII has long been known to be essential for synaptic plasticity and learning, recent work points to new dimensions of CaMKII function in the nervous system, revealing that CaMKII also plays an important role in synaptic organization. Ca(2+)-triggered autophosphorylation of CaMKII not only provides molecular memory by prolonging CaMKII activity during long-term plasticity (LTP) and learning but also represents a mechanism for autoactivation of CaMKII's multifaceted protein-docking functions. New details are also emerging about the distinct roles of CaMKIIα and CaMKIIβ in synaptic homeostasis, further illustrating the multilayered and complex nature of CaMKII's involvement in synaptic regulation. Here, I review novel molecular and functional insight into how CaMKII supports synaptic function.
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Affiliation(s)
- Johannes W Hell
- Department of Pharmacology, University of California, Davis, Davis, CA 95615, USA.
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79
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Núñez-Santana FL, Oh MM, Antion MD, Lee A, Hell JW, Disterhoft JF. Surface L-type Ca2+ channel expression levels are increased in aged hippocampus. Aging Cell 2014; 13:111-20. [PMID: 24033980 PMCID: PMC3947046 DOI: 10.1111/acel.12157] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2013] [Indexed: 12/30/2022] Open
Abstract
Age-related increase in L-type Ca2+ channel (LTCC) expression in hippocampal pyramidal neurons has been hypothesized to underlie the increased Ca2+ influx and subsequent reduced intrinsic neuronal excitability of these neurons that lead to age-related cognitive deficits. Here, using specific antibodies against Cav1.2 and Cav1.3 subunits of LTCCs, we systematically re-examined the expression of these proteins in the hippocampus from young (3 to 4 month old) and aged (30 to 32 month old) F344xBN rats. Western blot analysis of the total expression levels revealed significant reductions in both Cav1.2 and Cav1.3 subunits from all three major hippocampal regions of aged rats. Despite the decreases in total expression levels, surface biotinylation experiments revealed significantly higher proportion of expression on the plasma membrane of Cav1.2 in the CA1 and CA3 regions and of Cav1.3 in the CA3 region from aged rats. Furthermore, the surface biotinylation results were supported by immunohistochemical analysis that revealed significant increases in Cav1.2 immunoreactivity in the CA1 and CA3 regions of aged hippocampal pyramidal neurons. In addition, we found a significant increase in the level of phosphorylated Cav1.2 on the plasma membrane in the dentate gyrus of aged rats. Taken together, our present findings strongly suggest that age-related cognitive deficits cannot be attributed to a global change in L-type channel expression nor to the level of phosphorylation of Cav1.2 on the plasma membrane of hippocampal neurons. Rather, increased expression and density of LTCCs on the plasma membrane may underlie the age-related increase in L-type Ca2+ channel activity in CA1 pyramidal neurons.
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Affiliation(s)
- Félix Luis Núñez-Santana
- Department of Physiology; Feinberg School of Medicine; Northwestern University; Chicago IL 60611 USA
| | - Myongsoo Matthew Oh
- Department of Physiology; Feinberg School of Medicine; Northwestern University; Chicago IL 60611 USA
| | - Marcia Diana Antion
- Department of Physiology; Feinberg School of Medicine; Northwestern University; Chicago IL 60611 USA
| | - Amy Lee
- Departments of Molecular Physiology and Biophysics, Otolaryngology-Head and Neck Surgery, and Neurology; University of Iowa; Iowa City IA 52242 USA
| | | | - John Francis Disterhoft
- Department of Physiology; Feinberg School of Medicine; Northwestern University; Chicago IL 60611 USA
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Weiss S, Oz S, Benmocha A, Dascal N. Regulation of cardiac L-type Ca²⁺ channel CaV1.2 via the β-adrenergic-cAMP-protein kinase A pathway: old dogmas, advances, and new uncertainties. Circ Res 2013; 113:617-31. [PMID: 23948586 DOI: 10.1161/circresaha.113.301781] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the heart, adrenergic stimulation activates the β-adrenergic receptors coupled to the heterotrimeric stimulatory Gs protein, followed by subsequent activation of adenylyl cyclase, elevation of cyclic AMP levels, and protein kinase A (PKA) activation. One of the main targets for PKA modulation is the cardiac L-type Ca²⁺ channel (CaV1.2) located in the plasma membrane and along the T-tubules, which mediates Ca²⁺ entry into cardiomyocytes. β-Adrenergic receptor activation increases the Ca²⁺ current via CaV1.2 channels and is responsible for the positive ionotropic effect of adrenergic stimulation. Despite decades of research, the molecular mechanism underlying this modulation has not been fully resolved. On the contrary, initial reports of identification of key components in this modulation were later refuted using advanced model systems, especially transgenic animals. Some of the cardinal debated issues include details of specific subunits and residues in CaV1.2 phosphorylated by PKA, the nature, extent, and role of post-translational processing of CaV1.2, and the role of auxiliary proteins (such as A kinase anchoring proteins) involved in PKA regulation. In addition, the previously proposed crucial role of PKA in modulation of unstimulated Ca²⁺ current in the absence of β-adrenergic receptor stimulation and in voltage-dependent facilitation of CaV1.2 remains uncertain. Full reconstitution of the β-adrenergic receptor signaling pathway in heterologous expression systems remains an unmet challenge. This review summarizes the past and new findings, the mechanisms proposed and later proven, rejected or disputed, and emphasizes the essential issues that remain unresolved.
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Affiliation(s)
- Sharon Weiss
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel-Aviv, Israel.
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Adler EM. Bacteria under pressure, calcium channel internalization, and why cockroaches avoid glucose-baited traps. J Gen Physiol 2013; 142:1-2. [PMID: 23797418 PMCID: PMC3691450 DOI: 10.1085/jgp.201311041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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