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Ion channels as part of macromolecular multiprotein complexes : Clinical significance. Herzschrittmacherther Elektrophysiol 2017; 29:30-35. [PMID: 29214349 PMCID: PMC5846830 DOI: 10.1007/s00399-017-0542-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 10/11/2017] [Indexed: 11/17/2022]
Abstract
Ion channels and Ca2+-handling proteins involved in the regulation of cardiac electrophysiology and contractility are organized in macromolecular multiprotein complexes. Recent molecular and cellular studies have significantly enhanced our understanding of the composition of these macromolecular complexes and have helped to elucidate their role in the dynamic regulation of ion channel function. Moreover, it has become clear that alterations in the composition of ion channel macromolecular complexes, for example, due to genetic mutations or acquired alterations in the expression of individual components, may lead to ion channel dysfunction and arrhythmogenesis. Here, we review novel insights into the composition of the major ion channel macromolecular complexes and discuss the potential clinical significance of alterations in these dynamic multiprotein structures.
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Fuller MD, Fu Y, Scheuer T, Catterall WA. Differential regulation of CaV1.2 channels by cAMP-dependent protein kinase bound to A-kinase anchoring proteins 15 and 79/150. ACTA ACUST UNITED AC 2014; 143:315-24. [PMID: 24567507 PMCID: PMC3933935 DOI: 10.1085/jgp.201311075] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AKAP79/150 and AKAP15 exert functionally antagonistic effects on CaV1.2 channels. The CaV1.1 and CaV1.2 voltage-gated calcium channels initiate excitation-contraction coupling in skeletal and cardiac myocytes, excitation-transcription coupling in neurons, and many other cellular processes. Up-regulation of their activity by the β-adrenergic–PKA signaling pathway increases these physiological responses. PKA up-regulation of CaV1.2 activity can be reconstituted in a transfected cell system expressing CaV1.2Δ1800 truncated at the in vivo proteolytic processing site, the distal C-terminal domain (DCT; CaV1.2[1801–2122]), the auxiliary α2δ and β subunits of CaV1.2 channels, and A-kinase anchoring protein-15 (AKAP15), which binds to a site in the DCT. AKAP79/150 binds to the same site in the DCT as AKAP15. Here we report that AKAP79 is ineffective in supporting up-regulation of CaV1.2 channel activity by PKA, even though it binds to the same site in the DCT and inhibits the up-regulation of CaV1.2 channel activity supported by AKAP15. Mutation of the calcineurin-binding site in AKAP79 (AKAP79ΔPIX) allows it to support PKA-dependent up-regulation of CaV1.2 channel activity, suggesting that calcineurin bound to AKAP79 rapidly dephosphorylates CaV1.2 channels, thereby preventing their regulation by PKA. Both AKAP15 and AKAP79ΔPIX exert their regulatory effects on CaV1.2 channels in transfected cells by interaction with the modified leucine zipper motif in the DCT. Our results introduce an unexpected mode of differential regulation by AKAPs, in which binding of different AKAPs at a single site can competitively confer differential regulatory effects on the target protein by their association with different signaling proteins.
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Affiliation(s)
- Matthew D Fuller
- Department of Pharmacology, University of Washington, Seattle, WA 98195
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A promoter in the coding region of the calcium channel gene CACNA1C generates the transcription factor CCAT. PLoS One 2013; 8:e60526. [PMID: 23613729 PMCID: PMC3628902 DOI: 10.1371/journal.pone.0060526] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 02/27/2013] [Indexed: 11/26/2022] Open
Abstract
The C-terminus of the voltage-gated calcium channel Cav1.2 encodes a transcription factor, the calcium channel associated transcriptional regulator (CCAT), that regulates neurite extension and inhibits Cav1.2 expression. The mechanisms by which CCAT is generated in neurons and myocytes are poorly understood. Here we show that CCAT is produced by activation of a cryptic promoter in exon 46 of CACNA1C, the gene that encodes CaV1.2. Expression of CCAT is independent of Cav1.2 expression in neuroblastoma cells, in mice, and in human neurons derived from induced pluripotent stem cells (iPSCs), providing strong evidence that CCAT is not generated by cleavage of CaV1.2. Analysis of the transcriptional start sites in CACNA1C and immune-blotting for channel proteins indicate that multiple proteins are generated from the 3′ end of the CACNA1C gene. This study provides new insights into the regulation of CACNA1C, and provides an example of how exonic promoters contribute to the complexity of mammalian genomes.
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Zheng MQ, Li X, Tang K, Sharma NM, Wyatt TA, Patel KP, Gao L, Bidasee KR, Rozanski GJ. Pyruvate restores β-adrenergic sensitivity of L-type Ca(2+) channels in failing rat heart: role of protein phosphatase. Am J Physiol Heart Circ Physiol 2013; 304:H1352-60. [PMID: 23504177 DOI: 10.1152/ajpheart.00873.2012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Oxidative stress plays a major role in the pathogenesis of heart failure, where the contractile response to β-adrenergic stimulation is profoundly depressed. This condition involves L-type Ca(2+) channels, but the mechanisms underlying their impaired adrenergic regulation are unclear. Thus the present study explored the basis for impaired adrenergic control of Ca(2+) channels in a rat infarction model of heart failure. Patch-clamp recordings of L-type Ca(2+) current (I(Ca,L)) from ventricular myocytes isolated from infarcted hearts showed a blunted response to intracellular cAMP that was reversed by treatment with exogenous pyruvate. Biochemical studies showed that basal and cAMP-stimulated protein kinase A activities were similar in infarcted and sham-operated hearts, whereas molecular analysis also found that binding of protein kinase A to the α(1C) subunit of voltage-gated Ca(2+) channel isoform 1.2 was not different between groups. By contrast, protein phosphatase 2A (PP2A) activity and binding to α(1C) were significantly less in infarcted hearts. The PP2A inhibitor okadaic acid markedly increased I(Ca,L) in sham-operated myocytes, but this response was significantly less in myocytes from infarcted hearts. However, pyruvate normalized I(Ca,L) stimulation by okadaic acid, and this effect was blocked by inhibitors of thioredoxin reductase, implicating a functional role for the redox-active thioredoxin system. Our data suggest that blunted β-adrenergic stimulation of I(CaL) in failing hearts results from hyperphosphorylation of Ca(2+) channels secondary to oxidation-induced impairment of PP2A function. We propose that the redox state of Ca(2+) channels or PP2A is controlled by the thioredoxin system which plays a key role in Ca(2+) channel remodeling of the failing heart.
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Affiliation(s)
- Ming-Qi Zheng
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
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Sun Z, Hamilton KL, Reardon KF. Phosphoproteomics and molecular cardiology: Techniques, applications and challenges. J Mol Cell Cardiol 2012; 53:354-68. [DOI: 10.1016/j.yjmcc.2012.06.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 05/26/2012] [Accepted: 06/03/2012] [Indexed: 12/16/2022]
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Renigunta A, Mutig K, Rottermann K, Schlichthörl G, Preisig-Müller R, Daut J, Waldegger S, Renigunta V. The glycolytic enzymes glyceraldehyde 3-phosphate dehydrogenase and enolase interact with the renal epithelial K+ channel ROMK2 and regulate its function. Cell Physiol Biochem 2011; 28:663-72. [PMID: 22178878 DOI: 10.1159/000335761] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2011] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND/AIMS ROMK channels mediate potassium secretion and regulate NaCl reabsorption in the kidney. The aim was to study the functional implications of the interaction between ROMK2 (Kir1.1b) and two glycolytic enzymes, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and enolase-α, which were identified as potential regulatory subunits of the channel complex. METHODS We performed a membrane yeast-two-hybrid screen of a human kidney cDNA library with ROMK2 as a bait. Interaction of ROMK2 with GAPDH and enolase was verified using GST pull-down, co-immunoprecipitation, immunohistochemistry and co-expression in Xenopus oocytes. RESULTS Confocal imaging showed co-localisation of enolase and GAPDH with ROMK2 in the apical membrane of the renal epithelial cells of the thick ascending limb. Over-expression of GAPDH or enolase-α in Xenopus oocytes markedly reduced the amplitude of ROMK2 currents but did not affect the surface expression of the channels. Co-expression of the glycolytically inactive GAPDH mutant C149G did not have any effect on ROMK2 current amplitude. CONCLUSION Our results suggest that the glycolytic enzymes GAPDH and enolase are part of the ROMK2 channel supramolecular complex and may serve to couple salt reabsorption in the thick ascending limb of the loop of Henle to the metabolic status of the renal epithelial cells.
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Affiliation(s)
- Aparna Renigunta
- Department of Paediatric Nephrology, Children's Hospital, University of Marburg, Baldingerstrasse, Marburg, Germany
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Fu Y, Westenbroek RE, Yu FH, Clark JP, Marshall MR, Scheuer T, Catterall WA. Deletion of the distal C terminus of CaV1.2 channels leads to loss of beta-adrenergic regulation and heart failure in vivo. J Biol Chem 2011; 286:12617-26. [PMID: 21216955 DOI: 10.1074/jbc.m110.175307] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
L-type calcium currents conducted by CaV1.2 channels initiate excitation-contraction coupling in cardiac and vascular smooth muscle. In the heart, the distal portion of the C terminus (DCT) is proteolytically processed in vivo and serves as a noncovalently associated autoinhibitor of CaV1.2 channel activity. This autoinhibitory complex, with A-kinase anchoring protein-15 (AKAP15) bound to the DCT, is hypothesized to serve as the substrate for β-adrenergic regulation in the fight-or-flight response. Mice expressing CaV1.2 channels with the distal C terminus deleted (DCT-/-) develop cardiac hypertrophy and die prematurely after E15. Cardiac hypertrophy and survival rate were improved by drug treatments that reduce peripheral vascular resistance and hypertension, consistent with the hypothesis that CaV1.2 hyperactivity in vascular smooth muscle causes hypertension, hypertrophy, and premature death. However, in contrast to expectation, L-type Ca2+ currents in cardiac myocytes from DCT-/- mice were dramatically reduced due to decreased cell-surface expression of CaV1.2 protein, and the voltage dependence of activation and the kinetics of inactivation were altered. CaV1.2 channels in DCT-/- myocytes fail to respond to activation of adenylyl cyclase by forskolin, and the localized expression of AKAP15 is reduced. Therefore, we conclude that the DCT of CaV1.2 channels is required in vivo for normal vascular regulation, cell-surface expression of CaV1.2 channels in cardiac myocytes, and β-adrenergic stimulation of L-type Ca2+ currents in the heart.
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Affiliation(s)
- Ying Fu
- Department of Pharmacology, University of Washington, Seattle, Washington 98195-7280, USA
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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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Blayney LM, Lai FA. Ryanodine receptor-mediated arrhythmias and sudden cardiac death. Pharmacol Ther 2009; 123:151-77. [PMID: 19345240 PMCID: PMC2704947 DOI: 10.1016/j.pharmthera.2009.03.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Accepted: 03/03/2009] [Indexed: 12/25/2022]
Abstract
The cardiac ryanodine receptor-Ca2+ release channel (RyR2) is an essential sarcoplasmic reticulum (SR) transmembrane protein that plays a central role in excitation–contraction coupling (ECC) in cardiomyocytes. Aberrant spontaneous, diastolic Ca2+ leak from the SR due to dysfunctional RyR2 contributes to the formation of delayed after-depolarisations, which are thought to underlie the fatal arrhythmia that occurs in both heart failure (HF) and in catecholaminergic polymorphic ventricular tachycardia (CPVT). CPVT is an inherited disorder associated with mutations in either the RyR2 or a SR luminal protein, calsequestrin. RyR2 shows normal function at rest in CPVT but the RyR2 dysfunction is unmasked by physical exercise or emotional stress, suggesting abnormal RyR2 activation as an underlying mechanism. Several potential mechanisms have been advanced to explain the dysfunctional RyR2 observed in HF and CPVT, including enhanced RyR2 phosphorylation status, altered RyR2 regulation at luminal/cytoplasmic sites and perturbed RyR2 intra/inter-molecular interactions. This review considers RyR2 dysfunction in the context of the structural and functional modulation of the channel, and potential therapeutic strategies to stabilise RyR2 function in cardiac pathology.
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Affiliation(s)
- Lynda M Blayney
- Wales Heart Research Institute, Cardiff University School of Medicine, Cardiff CF144XN, UK.
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Abstract
Multimerin 1 is a massive, soluble, disulfide-linked homopolymeric protein that is expressed in megakaryocytes, platelets and endothelial cells. Normally, multimerin 1 undergoes efficient sorting to secretion granules, and it is not detectable in plasma. Recently, multimerin 1 was designated as a member of the EMILIN protein family, a group of structurally similar, disulfide-linked multimeric proteins. Multimerin 1 has the structural features of an adhesive protein and it supports the adhesion of many different cell types in vitro, including activated platelets, neutrophils, and endothelial cells. Multimerin 1 also has the ability to self associate and form large, branching matrix fibers. In platelet alpha-granules, multimerin 1 functions as the binding protein for coagulation factor V, a key regulator of coagulation. This review summarizes the current knowledge on multimerin 1 including its orthologous genes, restricted pattern of expression, structure, biosynthesis and functions.
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Affiliation(s)
- Samira B Jeimy
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
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Traaseth NJ, Verardi R, Veglia G. Asymmetric methyl group labeling as a probe of membrane protein homo-oligomers by NMR spectroscopy. J Am Chem Soc 2008; 130:2400-1. [PMID: 18247624 DOI: 10.1021/ja711499r] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nathaniel J Traaseth
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Few WP, Scheuer T, Catterall WA. Dopamine modulation of neuronal Na(+) channels requires binding of A kinase-anchoring protein 15 and PKA by a modified leucine zipper motif. Proc Natl Acad Sci U S A 2007; 104:5187-92. [PMID: 17360357 PMCID: PMC1829284 DOI: 10.1073/pnas.0611619104] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In hippocampal pyramidal cells, dopamine acts at D1 receptors to reduce peak Na(+) currents by activation of phosphorylation by PKA anchored via an A kinase-anchoring protein (AKAP15). However, the mechanism by which AKAP15 anchors PKA to neuronal Na(+) channels is not known. By using a strategy of coimmunoprecipitation from transfected tsA-201 cells, we have found that AKAP15 directly interacts with Na(v)1.2a channels via the intracellular loop between domains I and II. This loop contains key functional phosphorylation sites. Mutagenesis indicated that this interaction occurs through a modified leucine zipper motif near the N terminus of the loop. Whole-cell patch clamp recordings of acutely dissociated hippocampal pyramidal cells revealed that the D1 dopamine receptor agonist SKF 81297 reduces peak Na(+) current amplitude by 20.5%, as reported previously. Disruption of the leucine zipper interaction between Na(v)1.2a and AKAP15 through the inclusion of a small competing peptide in the patch pipette inhibited the SKF 81297-induced reduction in peak Na(+) current, whereas a control peptide with mutations in amino acids important for the leucine zipper interaction did not. Our results define the molecular mechanism by which G protein-coupled signaling pathways can rapidly and efficiently modulate neuronal excitability through local protein phosphorylation of Na(+) channels by specifically anchored PKA.
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Affiliation(s)
- W. Preston Few
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280
| | - Todd Scheuer
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280
| | - William A. Catterall
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280
- *To whom correspondence should be addressed. E-mail:
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Abstract
Adaptor or scaffolding proteins are at the basis of multiprotein complexes that spatially and temporally co-ordinate the propagation and integration of a broad range of cellular events. One class of scaffolding proteins are AKAPs (A-kinase-anchoring proteins). They sequester PKA (protein kinase A) and other signalling molecules including phosphodiesterases, other protein kinases and protein phosphatases to specific subcellular compartments. AKAP-dependent protein-protein interactions play a role in many physiologically relevant processes. For example, AKAP-PKA interactions are essential for the vasopressin-mediated water re-absorption in renal collecting duct principal cells or beta-adrenoceptor-induced increases in cardiac myocyte contractility. Here, we discuss recently developed peptide disruptors of AKAP-PKA interactions. Such peptides are valuable tools to study the relevance of PKA anchoring in cellular processes.
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Affiliation(s)
- C Hundsrucker
- Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Strasse 10, D-13125 Berlin, Germany
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Hundsrucker C, Krause G, Beyermann M, Prinz A, Zimmermann B, Diekmann O, Lorenz D, Stefan E, Nedvetsky P, Dathe M, Christian F, Mcsorley T, Krause E, Mcconnachie G, Herberg F, Scott J, Rosenthal W, Klussmann E. High-affinity AKAP7delta-protein kinase A interaction yields novel protein kinase A-anchoring disruptor peptides. Biochem J 2006; 396:297-306. [PMID: 16483255 PMCID: PMC1462715 DOI: 10.1042/bj20051970] [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] [Indexed: 11/17/2022]
Abstract
PKA (protein kinase A) is tethered to subcellular compartments by direct interaction of its regulatory subunits (RI or RII) with AKAPs (A kinase-anchoring proteins). AKAPs preferentially bind RII subunits via their RII-binding domains. RII-binding domains form structurally conserved amphipathic helices with unrelated sequences. Their binding affinities for RII subunits differ greatly within the AKAP family. Amongst the AKAPs that bind RIIalpha subunits with high affinity is AKAP7delta [AKAP18delta; K(d) (equilibrium dissociation constant) value of 31 nM]. An N-terminally truncated AKAP7delta mutant binds RIIalpha subunits with higher affinity than the full-length protein presumably due to loss of an inhibitory region [Henn, Edemir, Stefan, Wiesner, Lorenz, Theilig, Schmidtt, Vossebein, Tamma, Beyermann et al. (2004) J. Biol. Chem. 279, 26654-26665]. In the present study, we demonstrate that peptides (25 amino acid residues) derived from the RII-binding domain of AKAP7delta bind RIIalpha subunits with higher affinity (K(d)=0.4+/-0.3 nM) than either full-length or N-terminally truncated AKAP7delta, or peptides derived from other RII binding domains. The AKAP7delta-derived peptides and stearate-coupled membrane-permeable mutants effectively disrupt AKAP-RII subunit interactions in vitro and in cell-based assays. Thus they are valuable novel tools for studying anchored PKA signalling. Molecular modelling indicated that the high affinity binding of the amphipathic helix, which forms the RII-binding domain of AKAP7delta, with RII subunits involves both the hydrophobic and the hydrophilic faces of the helix. Alanine scanning (25 amino acid peptides, SPOT technology, combined with RII overlay assays) of the RII binding domain revealed that hydrophobic amino acid residues form the backbone of the interaction and that hydrogen bond- and salt-bridge-forming amino acid residues increase the affinity of the interaction.
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Affiliation(s)
- Christian Hundsrucker
- *Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Gerd Krause
- *Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Michael Beyermann
- *Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Anke Prinz
- †Institut für Biochemie, Universität Kassel, Heinrich-Plett-Str. 40, 34109 Kassel, Germany
| | | | - Oliver Diekmann
- ‡Biaffin GmbH & Co. KG, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Dorothea Lorenz
- *Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Eduard Stefan
- *Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Pavel Nedvetsky
- *Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Margitta Dathe
- *Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Frank Christian
- *Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Theresa Mcsorley
- *Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Eberhard Krause
- *Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - George Mcconnachie
- §Howard Hughes Medical Institute, Vollum Institute, Oregon Health and Science University, Portland, OR 97239, U.S.A
| | - Friedrich W. Herberg
- †Institut für Biochemie, Universität Kassel, Heinrich-Plett-Str. 40, 34109 Kassel, Germany
| | - John D. Scott
- §Howard Hughes Medical Institute, Vollum Institute, Oregon Health and Science University, Portland, OR 97239, U.S.A
| | - Walter Rosenthal
- *Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
- ¶Institut für Pharmakologie, Charité – Universitätsmedizin Berlin, Campus Benjamin Franklin, Freie Universität Berlin, Thielallee 67–73, 14195 Berlin, Germany
| | - Enno Klussmann
- *Leibniz-Institut für Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
- ¶Institut für Pharmakologie, Charité – Universitätsmedizin Berlin, Campus Benjamin Franklin, Freie Universität Berlin, Thielallee 67–73, 14195 Berlin, Germany
- To whom correspondence should be addressed (email )
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Compartmentalized cAMP signalling regulates vasopressin-mediated water reabsorption by controlling aquaporin-2. Biochem Soc Trans 2005; 33:1316-8. [PMID: 16246107 DOI: 10.1042/bst0331316] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The cAMP/PKA (protein kinase A) signalling pathway is activated by a plethora of stimuli. To facilitate the specificity of a cellular response, signal transduction complexes are formed and segregated to discrete sites (compartmentalization). cAMP/PKA signalling compartments are maintained by AKAPs (A-kinase anchoring proteins) which bind PKA and other signalling proteins, and by PDEs (phosphodiesterases). The latter hydrolyse cAMP and thus limit its diffusion and terminate PKA activity. An example of a cAMP-dependent process requiring compartmentalization of cAMP/PKA signals is arginine-vasopressin-regulated water reabsorption in renal principal cells. A detailed understanding of the protein interactions within a signal transduction complex offers the possibility to design agents influencing PKA binding to a specific AKAP, the targeting of an AKAP or the interactions of AKAPs with other signalling molecules. The ability to specifically modulate selected branches of a signal transduction pathway would greatly advance basic research, and may lead to new drugs suitable for the treatment of diseases caused by dysregulation of anchored PKA signalling (e.g. renal and cardiovascular diseases).
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Jo S, Lee KH, Song S, Jung YK, Park CS. Identification and functional characterization of cereblon as a binding protein for large-conductance calcium-activated potassium channel in rat brain. J Neurochem 2005; 94:1212-24. [PMID: 16045448 DOI: 10.1111/j.1471-4159.2005.03344.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Large-conductance Ca2+-activated K+ (BK(Ca)) channels are activated by membrane depolarization and modulated by intracellular Ca2+. Here, we report the direct interaction of cereblon (CRBN) with the cytosolic carboxy-terminus of the BK(Ca) channel alpha subunit (Slo). Rat CRBN contained the N-terminal domain of the Lon protease, a 'regulators of G protein-signaling' (RGS)-like domain, a leucine zipper (LZ) motif, and four putative protein kinase C (PKC) phosphorylation sites. RNA messages of rat cereblon (rCRBN) were widely distributed in different tissues with especially high-levels of expression in the brain. Direct association of rCRBN with the BK(Ca) channel was confirmed by immunoprecipitation in brain lysate, and the two proteins were co-localized in cultured rat hippocampal neurons. Ionic currents evoked by the rSlo channel were dramatically suppressed upon coexpression of rCRBN. rCRBN decreased the formation of the tetrameric rSlo complex thus reducing the surface expression of functional channels. Therefore, we suggest that CRBN may play an important role in assembly and surface expression of functional BK(Ca) channels by direct interaction with the cytosolic C-terminus of its alpha-subunit.
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Affiliation(s)
- Sooyeon Jo
- Department of Life Science, Gwangju Institute Science and Technology (GIST), Gwangju, Republic of Korea
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