1
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Chernyavskaya Y, Ebert AM, Milligan E, Garrity DM. Voltage-gated calcium channel CACNB2 (β2.1) protein is required in the heart for control of cell proliferation and heart tube integrity. Dev Dyn 2012; 241:648-62. [DOI: 10.1002/dvdy.23746] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2012] [Indexed: 01/11/2023] Open
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2
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Raybaud A, Baspinar EE, Dionne F, Dodier Y, Sauvé R, Parent L. The Role of Distal S6 Hydrophobic Residues in the Voltage-dependent Gating of CaV2.3 Channels. J Biol Chem 2007; 282:27944-52. [PMID: 17660294 DOI: 10.1074/jbc.m703895200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The hydrophobic locus VAVIM is conserved in the S6 transmembrane segment of domain IV (IVS6) in Ca(V)1 and Ca(V)2 families. Herein we show that glycine substitution of the VAVIM motif in Ca(V)2.3 produced whole cell currents with inactivation kinetics that were either slower (A1719G approximately V1720G), similar (V1718G), or faster (I1721G approximately M1722G) than the wild-type channel. The fast kinetics of I1721G were observed with a approximately +10 mV shift in its voltage dependence of activation (E(0.5,act)). In contrast, the slow kinetics of A1719G and V1720G were accompanied by a significant shift of approximately -20 mV in their E(0.5,act) indicating that the relative stability of the channel closed state was decreased in these mutants. Glycine scan performed with Val (349) in IS6, Ile(701) in IIS6, and Leu(1420) in IIIS6 at positions predicted to face Val(1720) in IVS6 also produced slow inactivating currents with hyperpolarizing shifts in the activation and inactivation potentials, again pointing out a decrease in the stability of the channel closed state. Mutations to other hydrophobic residues at these positions nearly restored the channel gating. Altogether these data indicate that residues at positions equivalent to 1720 exert a critical control upon the relative stability of the channel closed and open states and more specifically, that hydrophobic residues at these positions promote the channel closed state. We discuss a three-dimensional homology model of Ca(V)2.3 based upon Kv1.2 where hydrophobic residues at positions facing Val(1720) in IS6, IIS6, and IIIS6 play a critical role in stabilizing the closed state in Ca(V)2.3.
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Affiliation(s)
- Alexandra Raybaud
- Département de Physiologie and the Membrane Protein Research Group, Université de Montréal, Montréal, Québec H3C 3J7, Canada
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3
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Cingolani E, Ramirez Correa GA, Kizana E, Murata M, Cho HC, Marbán E. Gene Therapy to Inhibit the Calcium Channel β Subunit. Circ Res 2007; 101:166-75. [PMID: 17556655 DOI: 10.1161/circresaha.107.155721] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Calcium cycling figures prominently in excitation-contraction coupling and in various signaling cascades involved in the development of left ventricular hypertrophy. We hypothesized that genetic suppression of the L-type calcium channel accessory beta-subunit would modulate calcium current and suppress cardiac hypertrophy. A short hairpin RNA template sequence capable of mediating the knockdown of the L-type calcium channel accessory beta-subunit gene was incorporated into a lentiviral vector (PPT.CG.H1.beta(2)). Transduction of ventricular myocytes in vivo with the active short hairpin RNA partially inhibited the L-type calcium current. In neonatal rat cardiomyocytes, L-type calcium channel accessory beta-subunit gene knockdown reduced calcium transient amplitude. Similarly, [(3)H]leucine incorporation was attenuated in PPT.CG.H1.beta(2)-transduced neonatal rat cardiomyocytes compared with nonsilencing controls in a phenylephrine-induced hypertrophy model. In vivo gene transfer attenuated the hypertrophic response in an aortic-banded rat model of left ventricular hypertrophy, with reduced left ventricular wall thickness and heart weight/body weight ratios in PPT.CG.H1.beta(2)-injected rats at four weeks post transduction. Fractional shortening was preserved in rats treated with PPT.CG.H1.beta(2). These findings indicate that knockdown of L-type calcium channel accessory beta-subunit is capable of attenuating the hypertrophic response both in vitro and in vivo without compromising systolic performance. Suppression of the calcium channel beta subunit may represent a novel and useful therapeutic strategy for left ventricular hypertrophy.
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MESH Headings
- Animals
- Animals, Newborn
- Calcium Channels, L-Type/deficiency
- Calcium Channels, L-Type/metabolism
- Disease Models, Animal
- Gene Silencing
- Genetic Therapy
- Humans
- Hypertrophy, Left Ventricular/genetics
- Hypertrophy, Left Ventricular/metabolism
- Hypertrophy, Left Ventricular/pathology
- Hypertrophy, Left Ventricular/physiopathology
- Hypertrophy, Left Ventricular/therapy
- Lentivirus
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Organ Size/genetics
- Protein Subunits/deficiency
- Protein Subunits/metabolism
- Rats
- Transduction, Genetic
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Affiliation(s)
- Eugenio Cingolani
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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4
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Hullin R, Matthes J, von Vietinghoff S, Bodi I, Rubio M, D'Souza K, Friedrich Khan I, Rottländer D, Hoppe UC, Mohacsi P, Schmitteckert E, Gilsbach R, Bünemann M, Hein L, Schwartz A, Herzig S. Increased expression of the auxiliary beta(2)-subunit of ventricular L-type Ca(2)+ channels leads to single-channel activity characteristic of heart failure. PLoS One 2007; 2:e292. [PMID: 17356701 PMCID: PMC1808423 DOI: 10.1371/journal.pone.0000292] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Accepted: 02/19/2007] [Indexed: 11/25/2022] Open
Abstract
Background Increased activity of single ventricular L-type Ca2+-channels (L-VDCC) is a hallmark in human heart failure. Recent findings suggest differential modulation by several auxiliary β-subunits as a possible explanation. Methods and Results By molecular and functional analyses of human and murine ventricles, we find that enhanced L-VDCC activity is accompanied by altered expression pattern of auxiliary L-VDCC β-subunit gene products. In HEK293-cells we show differential modulation of single L-VDCC activity by coexpression of several human cardiac β-subunits: Unlike β1 or β3 isoforms, β2a and β2b induce a high-activity channel behavior typical of failing myocytes. In accordance, β2-subunit mRNA and protein are up-regulated in failing human myocardium. In a model of heart failure we find that mice overexpressing the human cardiac CaV1.2 also reveal increased single-channel activity and sarcolemmal β2 expression when entering into the maladaptive stage of heart failure. Interestingly, these animals, when still young and non-failing (“Adaptive Phase”), reveal the opposite phenotype, viz: reduced single-channel activity accompanied by lowered β2 expression. Additional evidence for the cause-effect relationship between β2-subunit expression and single L-VDCC activity is provided by newly engineered, double-transgenic mice bearing both constitutive CaV1.2 and inducible β2 cardiac overexpression. Here in non-failing hearts induction of β2-subunit overexpression mimicked the increase of single L-VDCC activity observed in murine and human chronic heart failure. Conclusions Our study presents evidence of the pathobiochemical relevance of β2-subunits for the electrophysiological phenotype of cardiac L-VDCC and thus provides an explanation for the single L-VDCC gating observed in human and murine heart failure.
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Affiliation(s)
- Roger Hullin
- Department of Cardiology, Swiss Heart Center Bern, University Hospital, Bern, Switzerland
- * To whom correspondence should be addressed. E-mail: (RH); (SH); (AS)
| | - Jan Matthes
- Department of Pharmacology, University of Cologne, Cologne, Germany
| | - Sibylle von Vietinghoff
- Department of Pharmacology, University of Wuerzburg, Wuerzburg, Germany
- Franz Volhard Clinic, Nephrology/Hypertension Section, Medical Faculty of the Charité, Berlin, Germany
| | - Ilona Bodi
- University of Cincinnati College of Medicine, Institute of Molecular Pharmacology and Biophysics, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Marta Rubio
- University of Cincinnati College of Medicine, Institute of Molecular Pharmacology and Biophysics, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Karen D'Souza
- University of Cincinnati College of Medicine, Institute of Molecular Pharmacology and Biophysics, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Ismail Friedrich Khan
- Department of Pharmacology, University of Cologne, Cologne, Germany
- Center of Molecular Medicine, University of Cologne, Cologne, Germany
| | | | - Uta C. Hoppe
- Center of Molecular Medicine, University of Cologne, Cologne, Germany
| | - Paul Mohacsi
- Department of Cardiology, Swiss Heart Center Bern, University Hospital, Bern, Switzerland
| | - Eva Schmitteckert
- Department of Pharmacology, University of Wuerzburg, Wuerzburg, Germany
| | - Ralf Gilsbach
- Department of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Moritz Bünemann
- Department of Pharmacology, University of Wuerzburg, Wuerzburg, Germany
| | - Lutz Hein
- Department of Pharmacology, University of Wuerzburg, Wuerzburg, Germany
- Department of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Arnold Schwartz
- University of Cincinnati College of Medicine, Institute of Molecular Pharmacology and Biophysics, University of Cincinnati, Cincinnati, Ohio, United States of America
- * To whom correspondence should be addressed. E-mail: (RH); (SH); (AS)
| | - Stefan Herzig
- Department of Pharmacology, University of Cologne, Cologne, Germany
- Center of Molecular Medicine, University of Cologne, Cologne, Germany
- * To whom correspondence should be addressed. E-mail: (RH); (SH); (AS)
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5
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Leach RN, Brette F, Orchard CH. Antisense oligonucleotide against the Ca channel beta subunit decreases L-type Ca current in rat ventricular myocytes. Biochem Biophys Res Commun 2006; 352:794-8. [PMID: 17141184 DOI: 10.1016/j.bbrc.2006.11.099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Accepted: 11/17/2006] [Indexed: 10/23/2022]
Abstract
The role of endogenous beta subunits of the L-type Ca channel in native cardiac ventricular myocytes is unclear. We have therefore investigated the effect of inhibiting beta subunit expression in rat myocytes, by culturing isolated myocytes for 24 h with either antisense oligonucleotide against the beta subunit or with scrambled oligonucleotide (control). Alpha1 subunit expression and distribution were then determined by immunolabeling, and L-type Ca current measured using the whole cell patch-clamp technique. Cells treated with antisense showed increased perinuclear staining for alpha1, decreased Ca current amplitude and a small rightward shift of the activation curve and the I-V relation, with no significant effect on inactivation. These data suggest that endogenous beta subunits in native cardiac myocytes help to traffic the alpha1 subunit to the cell membrane and thus play a major role in determining Ca current amplitude.
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Affiliation(s)
- Rob N Leach
- Institute of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
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6
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Lafond J, Simoneau L. Calcium Homeostasis in Human Placenta: Role of Calcium‐Handling Proteins. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 250:109-74. [PMID: 16861065 DOI: 10.1016/s0074-7696(06)50004-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The human placenta is a transitory organ, representing during pregnancy the unique connection between the mother and her fetus. The syncytiotrophoblast represents the specialized unit in the placenta that is directly involved in fetal nutrition, mainly involving essential nutrients, such as lipids, amino acids, and calcium. This ion is of particular interest since it is actively transported by the placenta throughout pregnancy and is associated with many roles during intrauterine life. At term, the human fetus has accumulated about 25-30 g of calcium. This transfer allows adequate fetal growth and development, since calcium is vital for fetal skeleton mineralization and many cellular functions, such as signal transduction, neurotransmitter release, and cellular growth. Thus, there are many proteins involved in calcium homeostasis in the human placenta.
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Affiliation(s)
- Julie Lafond
- Laboratoire de Physiologie Materno Foetale, Centre de recherche BioMed, Université du Québec à Montréal, Montréal, Canada, H3C 3P8
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7
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Leach RN, Desai JC, Orchard CH. Effect of cytoskeleton disruptors on L-type Ca channel distribution in rat ventricular myocytes. Cell Calcium 2005; 38:515-26. [PMID: 16137761 DOI: 10.1016/j.ceca.2005.07.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Revised: 06/16/2005] [Accepted: 07/19/2005] [Indexed: 11/22/2022]
Abstract
The cytoskeleton plays an important role in many aspects of cardiac cell function, including protein trafficking. However, the role of the cytoskeleton in determining Ca channel location in cardiac myocytes is unknown. In the present study we therefore investigated the effect of the cytoskeletal disruptors cytochalasin D, latrunculin, nocadazole and colchicine on the distribution of Ca channels in rat ventricular myocytes during culture for up to 96 h. During culture in the absence of these agents, cell edges became rounded, t-tubule density decreased, and the normal transverse distribution of the alpha1 (pore-forming) subunit of the L-type Ca channel became more punctate and peri-nuclear; these changes were associated with loss of synchronous Ca release in response to electrical stimulation. Disruption of tubulin using nocadazole or colchicine or sequestration of monomeric actin by latrunculin had no effect on these changes. In contrast, cytochalasin D inhibited these changes: cell shape, t-tubule density, transverse Ca channel staining and synchronous Ca release were maintained during culture. The protein synthesis inhibitor cycloheximide had similar effects to cytochalasin. These data suggest that cytochalasin stabilizes actin in adult ventricular myocytes in culture, thus stabilizing cell structure and function, and that actin is important in trafficking L-type Ca channels from the peri-nuclear region to the t-tubules, where they are normally located and provide the trigger for Ca release.
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Affiliation(s)
- R N Leach
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
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8
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Lebeche D, Dalal R, Jang M, del Monte F, Hajjar RJ. Transgenic Models of Heart Failure: Elucidation of the Molecular Mechanisms of Heart Disease. Heart Fail Clin 2005; 1:219-36. [PMID: 17386848 DOI: 10.1016/j.hfc.2005.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Djamel Lebeche
- Massachusetts General Hospital, Charlestown, MA 02129, USA.
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9
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Belkacemi L, Bédard I, Simoneau L, Lafond J. Calcium channels, transporters and exchangers in placenta: a review. Cell Calcium 2005; 37:1-8. [PMID: 15541458 DOI: 10.1016/j.ceca.2004.06.010] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Revised: 06/28/2004] [Accepted: 06/29/2004] [Indexed: 11/25/2022]
Abstract
Calcium (Ca2+) entry in cells is crucial for development and physiology of virtually all cell types. It acts as an intracellular (second) messenger to regulate a diverse array of cellular functions, from cell division and differentiation to cell death. Among candidates for Ca2+ entry in cells are-voltage-dependant Ca2+ channels (VDCCs), transient receptor potential (TRP)-related Ca2+ channels and store-operated Ca2+ (SOC) channels. Plasma membrane Ca2+-ATPases (PMCA) and Na+/Ca2+ exchanger (NCX) are mainly responsible for Ca2+ extrusion. These different Ca2+channels/transporters and exchangers exhibit specific distribution and physiological properties. During pregnancy, the syncytiotrophoblast layer of the human placenta transfers as much as 30 g of Ca2+ from the mother to the fetus, especially in late gestation where Ca2+ transport through different channels must increase in response to the demands of accelerating bone mineralization of the fetus. The identification and characterization of the different Ca2+ channels/transporters and exchangers on the brush-border membrane (BBM) facing the maternal circulation, and the basal plasma membrane (BPM) facing the fetal circulation; placental membrane of the syncytiotrophoblasts have been the focus of numerous studies. This review discusses current views in this field regarding localization and functions during transcellular Ca2+ entry and extrusion from cells particularly in the placenta.
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Affiliation(s)
- Louiza Belkacemi
- Laboratoire de Physiologie Materno-Foetale, Département des Sciences Biologiques, Université du Québec à Montréal, C.P. 8888, Succursale 'Centre-Ville'Montréal, Montréal, Québec, Canada H3C 3P8
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10
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Protas L, Barbuti A, Qu J, Rybin VO, Palmiter RD, Steinberg SF, Robinson RB. Neuropeptide Y Is an Essential In Vivo Developmental Regulator of Cardiac
I
Ca,L. Circ Res 2003; 93:972-9. [PMID: 14525809 DOI: 10.1161/01.res.0000099244.01926.56] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cell culture studies demonstrate an increase in cardiac L-type Ca
2+
current (
I
Ca,L
) density on sympathetic innervation in vitro and suggest the effect depends on neurally released neuropeptide Y (NPY). To determine if a similar mechanism contributes to the postnatal increase in
I
Ca,L
in vivo, we prepared isolated ventricular myocytes from neonatal and adult mice with targeted deletion of the NPY gene (
Npy
−/−
) and matched controls (
Npy
+/+
). Whole-cell voltage clamp demonstrates
I
Ca,L
density increases postnatally in
Npy
+/+
(by 56%), but is unchanged in
Npy
−/−
. Both
I
Ca,L
density and action potential duration are significantly greater in adult
Npy
+/+
than
Npy
−/−
myocytes, whereas
I
Ca,L
density is equivalent in neonatal
Npy
+/+
and
Npy
−/−
myocytes. These data indicate NPY does not influence
I
Ca,L
prenatally, but the postnatal increase in
I
Ca,L
density is entirely NPY-dependent. In contrast, there is a similar postnatal negative voltage shift in the
I
-V relation in
Npy
+/+
and
Npy
−/−
, indicating NPY does not influence the developmental change in
I
Ca,L
voltage-dependence. Immunoblot analyses and measurements of maximally activated
I
Ca,L
(in presence of forskolin or BayK 8644) show that the differences in current density between
Npy
+/+
and
Npy
−/−
cannot be attributed to altered Ca
2+
channel α
1C
subunit protein expression. Rather, these results suggest that the in vivo NPY-dependent postnatal increase in
I
Ca,L
density in cardiac myocytes results from regulation
I
Ca,L
properties by NPY.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Action Potentials/drug effects
- Action Potentials/genetics
- Action Potentials/physiology
- Animals
- Animals, Newborn
- Calcium Channel Agonists/pharmacology
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Cell Separation
- Colforsin/pharmacology
- Female
- Gene Expression Regulation, Developmental/physiology
- Heart Ventricles/cytology
- Heart Ventricles/growth & development
- Heart Ventricles/metabolism
- Male
- Mice
- Mice, Transgenic
- Myocardium/cytology
- Myocardium/metabolism
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Neuropeptide Y/deficiency
- Neuropeptide Y/genetics
- Neuropeptide Y/metabolism
- Patch-Clamp Techniques
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Affiliation(s)
- Lev Protas
- Department of Pharmacology, Columbia University, 630 W 168th St, New York, NY 10032, USA
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