101
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Quintana E, Torres Y, Alvarez C, Rojas A, Forero ME, Camacho M. Changes in macrophage membrane properties during early Leishmania amazonensis infection differ from those observed during established infection and are partially explained by phagocytosis. Exp Parasitol 2010; 124:258-64. [PMID: 19854174 DOI: 10.1016/j.exppara.2009.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 10/14/2009] [Accepted: 10/19/2009] [Indexed: 12/01/2022]
Affiliation(s)
- Eduardo Quintana
- Laboratorio de Biofísica, Centro Internacional de Física, Bogotá, Colombia
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102
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Solé L, Roura-Ferrer M, Pérez-Verdaguer M, Oliveras A, Calvo M, Fernández-Fernández JM, Felipe A. KCNE4 suppresses Kv1.3 currents by modulating trafficking, surface expression and channel gating. J Cell Sci 2009; 122:3738-48. [PMID: 19773357 DOI: 10.1242/jcs.056689] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Voltage-dependent potassium channels (Kv) play a crucial role in the activation and proliferation of leukocytes. Kv channels are either homo- or hetero-oligomers. This composition modulates their surface expression and serves as a mechanism for regulating channel activity. Kv channel interaction with accessory subunits provides mechanisms for channels to respond to stimuli beyond changes in membrane potential. Here, we demonstrate that KCNE4 (potassium voltage-gated channel subfamily E member 4), but not KCNE2, functions as an inhibitory Kv1.3 partner in leukocytes. Kv1.3 trafficking, targeting and activity are altered by the presence of KCNE4. KCNE4 decreases current density, slows activation, accelerates inactivation, increases cumulative inactivation, retains Kv1.3 in the ER and impairs channel targeting to lipid raft microdomains. KCNE4 associates with Kv1.3 in the ER and decreases the number of Kv1.3 channels at the cell surface, which diminishes cell excitability. Kv1.3 and KCNE4 are differentially regulated upon activation or immunosuppression in macrophages. Thus, lipopolysaccharide-induced activation increases Kv1.3 and KCNE4 mRNA, whereas dexamethasone triggers a decrease in Kv1.3 with no changes in KCNE4. The channelosome composition determines the activity and affects surface expression and membrane localization. Therefore, KCNE4 association might play a crucial role in controlling immunological responses. Our results indicate that KCNE ancillary subunits could be new targets for immunomodulation.
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Affiliation(s)
- Laura Solé
- Departament de Bioquímica i Biologia Molecular, Molecular Physiology Laboratory, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 645, 08028 Barcelona, Spain
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103
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Zsiros E, Kis-Toth K, Hajdu P, Gaspar R, Bielanska J, Felipe A, Rajnavolgyi E, Panyi G. Developmental switch of the expression of ion channels in human dendritic cells. THE JOURNAL OF IMMUNOLOGY 2009; 183:4483-92. [PMID: 19748986 DOI: 10.4049/jimmunol.0803003] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Modulation of the expression and activity of plasma membrane ion channels is one of the mechanisms by which immune cells can regulate their intracellular Ca(2+) signaling pathways required for proliferation and/or differentiation. Voltage-gated K+ channels, inwardly rectifying K+ channels, and Ca(2+)-activated K+ channels have been described to play a major role in controlling the membrane potential in lymphocytes and professional APCs, such as monocytes, macrophages, and dendritic cells (DCs). Our study aimed at the characterization and identification of ion channels expressed in the course of human DC differentiation from monocytes. We report in this study for the first time that immature monocyte-derived DCs express voltage-gated Na+ channels in their plasma membrane. The analysis of the biophysical and pharmacological properties of the current and PCR-based cloning revealed the presence of Nav1.7 channels in immature DCs. Transition from the immature to a mature differentiation state, however, was accompanied by the down-regulation of Nav1.7 expression concomitant with the up-regulation of voltage-gated Kv1.3 K+ channel expression. The presence of Kv1.3 channels seems to be common for immune cells; hence, selective Kv1.3 blockers may emerge as candidates for inhibiting various functions of mature DCs that involve their migratory, cytokine-secreting, and T cell-activating potential.
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Affiliation(s)
- Emese Zsiros
- Department of Biophysics and Cell Biology, University of Debrecen, Debrecen 4012, Hungary
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104
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Sun J, Mei Y, Guo X, Yin X, Zhao X, Wang Z, Yang L. Voltage-dependent K+-channel responses during activation and damage in alveolar macrophages induced by quartz particles. ACTA ACUST UNITED AC 2009; 29:404-8. [DOI: 10.1007/s11596-009-0402-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Indexed: 10/19/2022]
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105
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Keblesh JP, Dou H, Gendelman HE, Xiong H. 4-Aminopyridine improves spatial memory in a murine model of HIV-1 encephalitis. J Neuroimmune Pharmacol 2009; 4:317-27. [PMID: 19462247 DOI: 10.1007/s11481-009-9161-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Accepted: 05/08/2009] [Indexed: 11/24/2022]
Abstract
HIV-1-associated neurocognitive disorders (HAND) remains a significant source of morbidity in the era of wide spread use of highly active antiretroviral therapy. Disease is precipitated by low levels of viral growth and glial immune activation within the central nervous system. Blood borne macrophage and microglia affect a proinflammatory response and release viral proteins that affects neuronal viability and leads to death of nerve cells. Increasing evidence supports the notion that HAND is functional channelopathy, but proof of this concept remains incomplete. Based on their role in learning and memory processes, we now posit that voltage-gated potassium (K(v)) channels could be a functional substrate for disease. This was tested in the severe combined immunodeficient (SCID) mouse model of HIV-1 encephalitis (HIVE) by examining whether the K(v) channel blocker, 4-aminopyridine (4-AP), could affect behavioral, electrophysiological, and morphological measures of learning and memory. HIVE SCID mice showed impaired spatial memory in radial arm water maze tests. Electrophysiology studies revealed a reduction of long-term potentiation (LTP) in the CA1 region of the hippocampus. Importantly, systemic administration of 4-AP blocked HIV-1-associated reduction of LTP and improved animal performance in the radial arm water maze. These results support the importance of K(v) channel dysfunction in disease but, more importantly, provide a potential target for adjunctive therapies for HAND.
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Affiliation(s)
- James P Keblesh
- Neurophysiology Laboratory, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
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106
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Domínguez DM, Marín M, Camacho M. Macrophage ion currents are fit by a fractional model and therefore are a time series with memory. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 38:457-64. [PMID: 19132362 DOI: 10.1007/s00249-008-0395-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Revised: 11/12/2008] [Accepted: 12/08/2008] [Indexed: 11/26/2022]
Abstract
We studied macroscopic ion currents from macrophages and compared their patterns of behavior using classical and fractal analysis. Peak and steady state currents were measured respectively at the beginning and end of a voltage-clamp pulse. Hurst coefficients H and fractional dimensions were calculated for the current fluctuations (I(H)) during the intervening interval; these fluctuations are usually assumed to be white noise. We show that I(H) is different from 0.5 and that the increments are stationary, indicating that the dynamic model has memory and that the intervening current fluctuations cannot be considered as white noise. I(H) is less than 0.5, implying an antipersistent pattern. In addition, we show that the relation between inactivation and I(H) versus voltage V fit an equation I(H)(V) = f(V, alpha, m, d), where alpha is associated with fractional calculus and m and d are free parameters. Fitting by a fractional model confirms that the phenomenon has memory.
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Affiliation(s)
- Darío Manuel Domínguez
- Facultad de Ciencias, Universidad Militar Nueva Granada, Carrera 11 No. 101-80, Bogotá, Colombia
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107
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Shi CY, Wang R, Liu CX, Jiang H, Ma ZY, Li L, Zhang W. Simvastatin inhibits acidic extracellular pH-activated, outward rectifying chloride currents in RAW264.7 monocytic-macrophage and human peripheral monocytes. Int Immunopharmacol 2008; 9:247-52. [PMID: 19084616 DOI: 10.1016/j.intimp.2008.11.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 11/17/2008] [Accepted: 11/20/2008] [Indexed: 11/29/2022]
Abstract
Extracellular acidic pH activated chloride channels (I(Cl,acid)) have been characterized in HEK 293 cells and mammalian cardiac myocytes. This study was designed to evaluate the expression of I(Cl,acid) in RAW264.7 monocytic-macrophage and human peripheral monocytes and to investigate the effect of simvastatin on I(Cl,acid). In two kinds of cells, the activation and deactivation of the current rapidly and repeatedly followed the change of the extracellular solution to pH=4.3. Compared with the outward current (pA/pF) activated at pH 4.3, the currents inhibited by simvastatin at concentrations of 0.1 microM were all decreased a little, however the currents at concentrations of 1 microM and 10 microM simvastatin were decreased significantly. The IC(50) for simvastatin inhibiting I(Cl,acid) of RAW264.7 was 13.77 microM. In summary, we report for the first time that simvastatin inhibits the I(Cl,acid) of RAW264.7 monocytic-macrophage and human peripheral monocytes in a concentration-dependent manner.
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Affiliation(s)
- Cheng-Yao Shi
- Department of Pharmacy, QiLu Hospital, Shandong University, Jinan 250012, China
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108
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Bardou O, Trinh NTN, Brochiero E. Molecular diversity and function of K+ channels in airway and alveolar epithelial cells. Am J Physiol Lung Cell Mol Physiol 2008; 296:L145-55. [PMID: 19060226 DOI: 10.1152/ajplung.90525.2008] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Multiple K(+) channels are expressed in the respiratory epithelium lining airways and alveoli. Of the three main classes [1) voltage-dependent or Ca(2+)-activated, 6-transmembrane domains (TMD), 2) 2-pores 4-TMD, and 3) inward-rectified 2-TMD K(+) channels], almost 40 different transcripts have already been detected in the lung. The physiological and functional significance of this high molecular diversity of lung epithelial K(+) channels is intriguing. As detailed in the present review, K(+) channels are located at both the apical and basolateral membranes in the respiratory epithelium, where they mediate K(+) currents of diverse electrophysiological and regulatory properties. The main recognized function of K(+) channels is to control membrane potential and to maintain the driving force for transepithelial ion and liquid transport. In this manner, KvLQT1, KCa and K(ATP) channels, for example, contribute to the control of airway and alveolar surface liquid composition and volume. Thus, K(+) channel activation has been identified as a potential therapeutic strategy for the resolution of pathologies characterized by ion transport dysfunction. K(+) channels are also involved in other key functions in lung physiology, such as oxygen-sensing, inflammatory responses and respiratory epithelia repair after injury. The purpose of this review is to summarize and discuss what is presently known about the molecular identity of lung K(+) channels with emphasis on their role in lung epithelial physiology.
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Affiliation(s)
- Olivier Bardou
- Centre de recherche du CHUM, Hôtel-Dieu, 3840, Saint-Urbain, Montréal, Québec H2W 1T8, Canada
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109
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Monocyte chemotactic protein-1 regulates voltage-gated K+ channels and macrophage transmigration. J Neuroimmune Pharmacol 2008; 4:47-59. [PMID: 19034671 DOI: 10.1007/s11481-008-9135-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Accepted: 10/31/2008] [Indexed: 10/21/2022]
Abstract
Progressive human immunodeficiency virus (HIV)-1 infection and virus-induced neuroinflammatory responses effectuate monocyte-macrophage transmigration across the blood-brain barrier (BBB). A key factor in mediating these events is monocyte chemotactic protein-1 (MCP-1). Upregulated glial-derived MCP-1 in HIV-1-infected brain tissues generates a gradient for monocyte recruitment into the nervous system. We posit that the inter-relationships between MCP-1, voltage-gated ion channels, cell shape and volume, and cell mobility underlie monocyte transmigration across the BBB. In this regard, MCP-1 serves both as a chemoattractant and an inducer of monocyte-macrophage ion flux affecting cell shape and mobility. To address this hypothesis, MCP-1-treated bone marrow-derived macrophages (BMM) were analyzed for gene and protein expression, electrophysiology, and capacity to migrate across a laboratory constructed BBB. MCP-1 enhanced K+ channel gene (KCNA3) and channel protein expression. Electrophysiological studies revealed that MCP-1 increased outward K+ currents in a dose-dependent manner. In vitro studies demonstrated that MCP-1 increased BMM migration across an artificial BBB, and the MCP-1-induced BMM migration was blocked by tetraethylammonium, a voltage-gated K+ channel blocker. Together these data demonstrated that MCP-1 affects macrophage migratory movement through regulation of voltage-gated K+ channels and, as such, provides a novel therapeutic strategy for neuroAIDS.
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110
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Matzner N, Zemtsova IM, Xuan NT, Duszenko M, Shumilina E, Lang F. Ion Channels Modulating Mouse Dendritic Cell Functions. THE JOURNAL OF IMMUNOLOGY 2008; 181:6803-9. [DOI: 10.4049/jimmunol.181.10.6803] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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111
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Martínez-Mármol R, Villalonga N, Solé L, Vicente R, Tamkun MM, Soler C, Felipe A. Multiple Kv1.5 targeting to membrane surface microdomains. J Cell Physiol 2008; 217:667-73. [PMID: 18668522 DOI: 10.1002/jcp.21538] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Surface expression of voltage-dependent K(+) channels (Kv) has a pivotal role in leukocyte physiology. Although little is known about the physiological role of lipid rafts, these microdomains concentrate signaling molecules and their ion channel substrates. Kv1.3 associates with Kv1.5 to form functional channels in macrophages. Different isoform stoichiometries lead to distinct heteromeric channels which may be further modulated by targeting the complex to different membrane surface microdomains. Kv1.3 targets to lipid rafts, whereas Kv1.5 localization is under debate. With this in mind, we wanted to study whether heterotetrameric Kv1.5-containing channels target to lipid rafts. While in transfected HEK-293 cells, homo- and heterotetrameric channels targeted to rafts, Kv1.5 did not target to rafts in macrophages. Therefore, Kv1.3/Kv1.5 hybrid channels are mostly concentrated in non-raft microdomains. However, LPS-induced activation, which increases the Kv1.3/Kv1.5 ratio and caveolin, targeted Kv1.5 back to lipid rafts. Moreover, Kv1.5 did not localize to low-buoyancy fractions in L6E9 skeletal myoblasts, which also coexpress both channels, heart membranes or cardiomyocyes. Coexpression of a Cav3(DGV)-mutant confined Kv1.5 to Cav3(DGV)-vesicles of HEK cells. Contrarily, coexpression of Kvbeta2.1 impaired the Kv1.5 targeting to raft microdomains in HEK cells. Our results indicate that Kv1.5 partnership interactions are underlying mechanisms governing channel targeting to lipid rafts.
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Affiliation(s)
- Ramón Martínez-Mármol
- Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina, Universitat de Barcelona, Barcelona, Spain
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112
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Wei JF, Wei L, Zhou X, Lu ZY, Francis K, Hu XY, Liu Y, Xiong WC, Zhang X, Banik NL, Zheng SS, Yu SP. Formation of Kv2.1-FAK complex as a mechanism of FAK activation, cell polarization and enhanced motility. J Cell Physiol 2008; 217:544-57. [PMID: 18615577 DOI: 10.1002/jcp.21530] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Focal adhesion kinase (FAK) plays key roles in cell adhesion and migration. We now report that the delayed rectifier Kv2.1 potassium channel, through its LD-like motif in N-terminus, may interact with FAK and enhance phosphorylation of FAK(397) and FAK(576/577). Overlapping distribution of Kv2.1 and FAK was observed on soma and proximal dendrites of cortical neurons. FAK expression promotes a polarized membrane distribution of the Kv2.1 channel. In Kv2.1-transfected CHO cells, formation of the Kv2.1-FAK complex was stimulated by fibronectin/integrin and inhibited by the K(+) channel blocker tetraethylammonium (TEA). FAK phosphorylation was minimized by shRNA knockdown of the Kv2.1 channel, point mutations of the N-terminus, and TEA, respectively. Cell migration morphology was altered by Kv2.1 knockdown or TEA, hindering cell migration activity. In wound healing tests in vitro and a traumatic injury animal model, Kv2.1 expression and co-localization of Kv2.1 and FAK significantly enhanced directional cell migration and wound closure. It is suggested that the Kv2.1 channel may function as a promoting signal for FAK activation and cell motility.
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Affiliation(s)
- Jian-Feng Wei
- Key Laboratory of Combined Multi-organ Transplantation of Ministry of Health China, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
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113
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Camacho M, Forero ME, Fajardo C, Niño A, Morales P, Campos H. Leishmania amazonensis infection may affect the ability of the host macrophage to be activated by altering their outward potassium currents. Exp Parasitol 2008; 120:50-6. [PMID: 18571651 DOI: 10.1016/j.exppara.2008.04.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 04/22/2008] [Accepted: 04/28/2008] [Indexed: 02/04/2023]
Abstract
Understanding the impact of intracellular pathogens on the behaviour of their host cells is key to designing new interventions. We are interested in how Leishmania alters the electrical functioning of the plasma membrane of the macrophage it infects. The specific question addressed here is whether Leishmania amazonensis infection alters the macrophage's outward currents and what the consequences of such changes might be. Using the whole cell configuration of the patch clamp technique, we show that outward peak current density remains constant over the period studied but that time to peak and sensitivity to inhibitors vary during infection. Infected cells take 40% longer to activate and are more sensitive to the potassium channel inhibitor tetraethyl ammonium, compared to control cells, indicating increased potassium outward current activity. Activation of macrophages is associated with increases of nitric oxide production and membrane area, depolarization of the macrophage membrane, down regulation of inward potassium and up regulation of outward currents. After Leishmania infection, macrophage activation is characterised by a reduction of nitric oxide production and of outward current density. We therefore suggest that this reflects a weaker activation.
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Affiliation(s)
- Marcela Camacho
- Departamento de Biología, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia.
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114
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Villalonga N, Martínez-Mármol R, Roura-Ferrer M, David M, Valenzuela C, Soler C, Felipe A. Cell cycle-dependent expression of Kv1.5 is involved in myoblast proliferation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:728-36. [DOI: 10.1016/j.bbamcr.2008.01.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 11/26/2007] [Accepted: 01/02/2008] [Indexed: 12/01/2022]
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115
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Wulff H, Zhorov BS. K+ channel modulators for the treatment of neurological disorders and autoimmune diseases. Chem Rev 2008; 108:1744-73. [PMID: 18476673 PMCID: PMC2714671 DOI: 10.1021/cr078234p] [Citation(s) in RCA: 168] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Heike Wulff
- Department of Pharmacology, University of California, Davis, California 95616, USA.
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116
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Roura-Ferrer M, Solé L, Martínez-Mármol R, Villalonga N, Felipe A. Skeletal muscle Kv7 (KCNQ) channels in myoblast differentiation and proliferation. Biochem Biophys Res Commun 2008; 369:1094-7. [PMID: 18331828 DOI: 10.1016/j.bbrc.2008.02.152] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Accepted: 02/29/2008] [Indexed: 10/22/2022]
Abstract
Voltage-dependent K(+) channels (Kv) are involved in myocyte proliferation and differentiation by triggering changes in membrane potential and regulating cell volume. Since Kv7 channels may participate in these events, the purpose of this study was to investigate whether skeletal muscle Kv7.1 and Kv7.5 were involved during proliferation and myogenesis. Here we report that, while myotube formation did not regulate Kv7 channels, Kv7.5 was up-regulated during cell cycle progression. Although, Kv7.1 mRNA also increased during the G(1)-phase, pharmacological evidence mainly involves Kv7.5 in myoblast growth. Our results indicate that the cell cycle-dependent expression of Kv7.5 is involved in skeletal muscle cell proliferation.
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Affiliation(s)
- Meritxell Roura-Ferrer
- Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina, Universitat de Barcelona, Avda. Diagonal 645, E-08028 Barcelona, Spain
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117
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Vicente R, Villalonga N, Calvo M, Escalada A, Solsona C, Soler C, Tamkun MM, Felipe A. Kv1.5 association modifies Kv1.3 traffic and membrane localization. J Biol Chem 2008; 283:8756-64. [PMID: 18218624 DOI: 10.1074/jbc.m708223200] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Kv1.3 activity is determined by raft association. In addition to Kv1.3, leukocytes also express Kv1.5, and both channels control physiological responses. Because the oligomeric composition may modify the channel targeting to the membrane, we investigated heterotetrameric Kv1.3/Kv1.5 channel traffic and targeting in HEK cells. Kv1.3 and Kv1.5 generate multiple heterotetramers with differential surface expression according to the subunit composition. FRET analysis and pharmacology confirm the presence of functional hybrid channels. Raft association was evaluated by cholesterol depletion, caveolae colocalization, and lateral diffusion at the cell surface. Immunoprecipitation showed that both Kv1.3 and heteromeric channels associate with caveolar raft domains. However, homomeric Kv1.3 channels showed higher association with caveolin traffic. Moreover, FRAP analysis revealed higher mobility for hybrid Kv1.3/Kv1.5 than Kv1.3 homotetramers, suggesting that heteromers target to distinct surface microdomains. Studies with lipopolysaccharide-activated macrophages further supported that different physiological mechanisms govern Kv1.3 and Kv1.5 targeting to rafts. Our results implicate the traffic and localization of Kv1.3/Kv1.5 heteromers in the complex regulation of immune system cells.
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Affiliation(s)
- Rubén Vicente
- Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina, Universitat de Barcelona, Barcelona, Spain
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118
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Irvine E, Keblesh J, Liu J, Xiong H. Voltage-gated potassium channel modulation of neurotoxic activity in human immunodeficiency virus type-1(HIV-1)-infected macrophages. J Neuroimmune Pharmacol 2007; 2:265-9. [PMID: 18040860 DOI: 10.1007/s11481-007-9072-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Accepted: 03/15/2007] [Indexed: 11/30/2022]
Abstract
Macrophages play an important role in brain immune and inflammatory responses. They are also critical cells in mediating the pathology of neurodegenerative disorders such as HIV-associated dementia. This is largely through their capacity to secrete a variety of bioactive molecules such as cytokines, leading to neuronal dysfunction and/or death. Accumulating evidence indicates that voltage-gated potassium (Kv) channels play a pivotal role in the modulation of macrophage proliferation, activation, and secretion. Blockade of Kv channels by specific antagonists decreases macrophage cytokine production and ameliorates macrophage-associated neuronal injury. These results suggest that Kv channels might become a potential target for the development of new therapeutic strategies for chronic inflammatory diseases.
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Affiliation(s)
- Elizabeth Irvine
- Neurophysiology Laboratory, the Center for Neurovirology and Neurodegenerative Disorders, and Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
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119
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Thomas MP, Chartrand K, Reynolds A, Vitvitsky V, Banerjee R, Gendelman HE. Ion channel blockade attenuates aggregated alpha synuclein induction of microglial reactive oxygen species: relevance for the pathogenesis of Parkinson's disease. J Neurochem 2007; 100:503-19. [PMID: 17241161 DOI: 10.1111/j.1471-4159.2006.04315.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Brain mononuclear phagocyte (perivascular macrophage and microglia, MG) inflammatory neurotoxins play a principal role in the pathogenesis of Parkinson's disease; chief among these are reactive oxygen species (ROS). We posit that aggregated, misfolded and oxidized alpha-synuclein (a major constituent of Lewy bodies), released or secreted from dying dopaminergic neurons, induces microglial ROS production that is regulated by ion channels and as such affects disease progression. To address this hypothesis, we performed patch clamp recordings of outward ionic currents in murine microglia and characterized their links to ROS production during alpha-synuclein stimulation. Aggregated nitrated alpha-synuclein induced ROS production in a dose-dependent manner that was inhibited by voltage-gated potassium current blockade, and to a more limited degree, by chloride current blockade. Interestingly, ROS produced in MG primed with tumor necrosis factor alpha and activated with phorbol myristate acetate was attenuated by voltage-gated potassium current blockade and more completely by chloride current blockade. In contrast, amyloid beta or cell membrane extract failed to induce microglial ROS production. Similar results were obtained using bone marrow-derived macrophages. The association of ROS production with specific plasma membrane ion currents provides a link between regulation of microglial ion transport and oxygen free radical production. Understanding these linkages may lead to novel therapeutics for Parkinson's disease where modulation of redox-related stress may slow disease progression.
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Affiliation(s)
- Mark P Thomas
- Laboratory of Neuroregeneration, Center for Neurovirology and Neurodegenerative Disorders, University of Nebraska Medical Center, Omaha, Nebraska 68198-5880, USA.
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120
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Azam P, Sankaranarayanan A, Homerick D, Griffey S, Wulff H. Targeting effector memory T cells with the small molecule Kv1.3 blocker PAP-1 suppresses allergic contact dermatitis. J Invest Dermatol 2007; 127:1419-29. [PMID: 17273162 PMCID: PMC1929164 DOI: 10.1038/sj.jid.5700717] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The voltage-gated potassium channel Kv1.3 has been recently identified as a molecular target that allows for selective pharmacological suppression of effector memory T (T(EM)) cells without affecting the function of naïve and central memory T cells. We here investigated whether PAP-1, a small molecule Kv1.3 blocker (EC50=2 nM), could suppress allergic contact dermatitis (ACD). In a rat model of ACD, we first confirmed that the infiltrating cells in the elicitation phase are indeed CD8+ CD45RC- memory T cells with high Kv1.3 expression. In accordance with its selective effect on T(EM) cells, PAP-1 did not impair sensitization, but potently suppressed oxazolone-induced inflammation by inhibiting the infiltration of CD8+ T cells and reducing the production of the inflammatory cytokines IFN-gamma, IL-2, and IL-17 when administered intraperitoneally or orally during the elicitation phase. PAP-1 was equally effective when applied topically, demonstrating that it effectively penetrates skin. We further show that PAP-1 is not a sensitizer or an irritant and exhibits no toxicity in a 28-day toxicity study. Based on these results we propose that PAP-1 could potentially be developed into a drug for the topical treatment of inflammatory skin diseases such as psoriasis.
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Affiliation(s)
- Philippe Azam
- Department of Medical Pharmacology and Toxicology, University of California, Davis, California, USA
| | | | - Daniel Homerick
- Department of Medical Pharmacology and Toxicology, University of California, Davis, California, USA
| | - Stephen Griffey
- Comparative Pathology Laboratory University of California, Davis, California, USA
| | - Heike Wulff
- Department of Medical Pharmacology and Toxicology, University of California, Davis, California, USA
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121
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Villalonga N, Escalada A, Vicente R, Sánchez-Tilló E, Celada A, Solsona C, Felipe A. Kv1.3/Kv1.5 heteromeric channels compromise pharmacological responses in macrophages. Biochem Biophys Res Commun 2007; 352:913-8. [PMID: 17157812 DOI: 10.1016/j.bbrc.2006.11.120] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Accepted: 11/21/2006] [Indexed: 12/31/2022]
Abstract
Voltage-dependent K(+) (Kv) channels are involved in the immune response. Kv1.3 is highly expressed in activated macrophages and T-effector memory cells of autoimmune disease patients. Macrophages are actively involved in T-cell activation by cytokine production and antigen presentation. However, unlike T-cells, macrophages express Kv1.5, which is resistant to Kv1.3-drugs. We demonstrate that mononuclear phagocytes express different Kv1.3/Kv1.5 ratios, leading to biophysically and pharmacologically distinct channels. Therefore, Kv1.3-based treatments to alter physiological responses, such as proliferation and activation, are impaired by Kv1.5 expression. The presence of Kv1.5 in the macrophagic lineage should be taken into account when designing Kv1.3-based therapies.
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Affiliation(s)
- Núria Villalonga
- Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Avda. Diagonal 645, E-08028 Barcelona, Spain
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122
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Vicente R, Escalada A, Villalonga N, Texidó L, Roura-Ferrer M, Martín-Satué M, López-Iglesias C, Soler C, Solsona C, Tamkun MM, Felipe A. Association of Kv1.5 and Kv1.3 contributes to the major voltage-dependent K+ channel in macrophages. J Biol Chem 2006; 281:37675-85. [PMID: 17038323 DOI: 10.1074/jbc.m605617200] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Voltage-dependent K(+) (Kv) currents in macrophages are mainly mediated by Kv1.3, but biophysical properties indicate that the channel composition could be different from that of T-lymphocytes. K(+) currents in mouse bone marrow-derived and Raw-264.7 macrophages are sensitive to Kv1.3 blockers, but unlike T-cells, macrophages express Kv1.5. Because Shaker subunits (Kv1) may form heterotetrameric complexes, we investigated whether Kv1.5 has a function in Kv currents in macrophages. Kv1.3 and Kv1.5 co-localize at the membrane, and half-activation voltages and pharmacology indicate that K(+) currents may be accounted for by various Kv complexes in macrophages. Co-expression of Kv1.3 and Kv1.5 in human embryonic kidney 293 cells showed that the presence of Kv1.5 leads to a positive shift in K(+) current half-activation voltages and that, like Kv1.3, Kv1.3/Kv1.5 heteromers are sensitive to r-margatoxin. In addition, both proteins co-immunoprecipitate and co-localize. Fluorescence resonance energy transfer studies further demonstrated that Kv1.5 and Kv1.3 form heterotetramers. Electrophysiological and pharmacological studies of different ratios of Kv1.3 and Kv1.5 co-expressed in Xenopus oocytes suggest that various hybrids might be responsible for K(+) currents in macrophages. Tumor necrosis factor-alpha-induced activation of macrophages increased Kv1.3 with no changes in Kv.1.5, which is consistent with a hyperpolarized shift in half-activation voltage and a lower IC(50) for margatoxin. Taken together, our results demonstrate that Kv1.5 co-associates with Kv1.3, generating functional heterotetramers in macrophages. Changes in the oligomeric composition of functional Kv channels would give rise to different biophysical and pharmacological properties, which could determine specific cellular responses.
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Affiliation(s)
- Rubén Vicente
- Molecular Physiology Laboratory, Departament de Bioquiámica i Biologia Molecular, Departament de Fisiologia, and Unitat de Reconeixement Molecular in situ, Serveis Cientificotècnics Universitat de Barcelona, E-08028 Barcelona, Spain
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123
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Potassium channels: new targets in cancer therapy. ACTA ACUST UNITED AC 2006; 30:375-85. [PMID: 16971052 DOI: 10.1016/j.cdp.2006.06.002] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2006] [Indexed: 01/01/2023]
Abstract
BACKGROUND Potassium channels (KCh) are the most diverse and ubiquitous class of ion channels. KCh control membrane potential and contribute to nerve and cardiac action potentials and neurotransmitter release. KCh are also involved in insulin release, differentiation, activation, proliferation, apoptosis, and several other physiological functions. The aim of this review is to provide an updated overview of the KCh role during the cell growth. Their potential use as pharmacological targets in cancer therapies is also discussed. METHODS We searched PubMed (up to 2005) and identified relevant articles. Reprints were mainly obtained by on line subscription. Additional sources were identified through cross-referencing and obtained from Library services. RESULTS KCh are responsible for some neurological and cardiovascular diseases and for a new medical discipline, channelopathies. Their role in congenital deafness, multiple sclerosis, episodic ataxia, LQT syndrome and diabetes has been proven. Furthermore, a large body of information suggests that KCh play a role in the cell cycle progression, and it is now accepted that cells require KCh to proliferate. Thus, KCh expression has been studied in a number of tumours and cancer cells. CONCLUSIONS Cancer is far from being considered a channelopathy. However, it seems appropriate to take into account the involvement of KCh in cancer progression and pathology when developing new strategies for cancer therapy.
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124
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Abstract
One of the functional roles of the corneal epithelial layer is to protect the cornea, lens and other underlying ocular structures from damages caused by environmental insults. It is important for corneal epithelial cells to maintain this function by undergoing continuous renewal through a dynamic process of wound healing. Previous studies in corneal epithelial cells have provided substantial evidence showing that environmental insults, such as ultraviolet (UV) irradiation and other biohazards, can induce stress-related cellular responses resulting in apoptosis and thus interrupt the dynamic process of wound healing. We found that UV irradiation-induced apoptotic effects in corneal epithelial cells are started by the hyperactivation of K+ channels in the cell membrane resulting in a fast loss of intracellular K+ ions. Recent studies provide further evidence indicating that these complex responses in corneal epithelial cells are resulted from the activation of stress-related signaling pathways mediated by K+ channel activity. The effect of UV irradiation on corneal epithelial cell fate shares common signaling mechanisms involving the activation of intracellular responses that are often activated by the stimulation of various cytokines. One piece of evidence for making this distinction is that at early times UV irradiation activates a Kv3.4 channel in corneal epithelial cells to elicit activation of c-Jun N-terminal kinase cascades and p53 activation leading to cell cycle arrest and apoptosis. The hypothetic model is that UV-induced potassium channel hyperactivity as an early event initiates fast cell shrinkages due to the loss of intracellular potassium, resulting in the activation of scaffolding protein kinases and cytoskeleton reorganizations. This review article presents important control mechanisms that determine Kv channel activity-mediated cellular responses in corneal epithelial cells, involving activation of stress-induced signaling pathways, arrests of cell cycle progression and/or induction of apoptosis.
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Affiliation(s)
- Luo Lu
- Department of Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California Los Angeles, Harbor-UCLA Medical Center, CA 90502, USA.
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125
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Yeramian A, Martin L, Arpa L, Bertran J, Soler C, McLeod C, Modolell M, Palacín M, Lloberas J, Celada A. Macrophages require distinct arginine catabolism and transport systems for proliferation and for activation. Eur J Immunol 2006; 36:1516-26. [PMID: 16703566 DOI: 10.1002/eji.200535694] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In murine macrophages, as a result of arginine catabolism during activation, citruline is produced under the effect of IFN-gamma and LPS, and ornithine and polyamines by IL-4 and IL-10. For proliferation, arginine is required from the extracellular medium and is used for protein synthesis. During activation, most arginine (>95% in 6 h) was metabolized, while under proliferation only half was incorporated into proteins. Under basal conditions, this amino acid was preferentially transported by y(+)L activity. During activation, arginine transport increased drastically (4-5-fold) through y(+) cationic amino acid transporter (CAT) activity. By contrast, M-CSF induced only a modest increase in uptake (0.5-fold). The increase in arginine transport during activation, but not proliferation, was mediated by the SLC7A2/Cat2 gene. SLC7A1/Cat1 is constitutively expressed, and is not modified by proliferating or activating agents. M-CSF-dependent proliferation was not affected in the macrophages of SLC7A2 knockout mice; however, these cells showed a drastic reduction in the production of citruline or ornithine and polyamines during activation. The data show that a large increase in a specific transport system (CAT2) is necessary for activation-induced arginine metabolism, while arginine is in excess for the requirements of proliferation and a modest increase in transport occurs.
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Affiliation(s)
- Andrée Yeramian
- Macrophage Biology Group, Institute of Research in Biomedicine, Barcelona Science Park, Spain
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126
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Mullen KM, Rozycka M, Rus H, Hu L, Cudrici C, Zafranskaia E, Pennington MW, Johns DC, Judge SIV, Calabresi PA. Potassium channels Kv1.3 and Kv1.5 are expressed on blood-derived dendritic cells in the central nervous system. Ann Neurol 2006; 60:118-27. [PMID: 16729292 DOI: 10.1002/ana.20884] [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: 12/25/2022]
Abstract
OBJECTIVE Potassium (K(+)) channels on immune cells have gained attention recently as promising targets of therapy for immune-mediated neurological diseases such as multiple sclerosis (MS). We examined K(+) channels on dendritic cells (DCs), which infiltrate the brain in MS and may impact disease course. METHODS We identified K(+) channels on blood-derived DCs by whole-cell patch-clamp analysis, confirmed by immunofluorescent staining. We also stained K(+) channels in brain sections from MS patients and control subjects. To test functionality, we blocked K(v)1.3 and K(v)1.5 in stimulated DCs with pharmacological blockers or with an inducible dominant-negative K(v)1.x adenovirus construct and analyzed changes in costimulatory molecule upregulation. RESULTS Electrophysiological analysis of DCs showed an inward-rectifying K(+) current early after stimulation, replaced by a mix of voltage-gated K(v)1.3- and K(v)1.5-like channels at later stages of maturation. K(v)1.3 and K(v)1.5 were also highly expressed on DCs infiltrating MS brain tissue. Of note, we found that CD83, CD80, CD86, CD40, and interleukin-12 upregulation were significantly impaired on K(v)1.3 and K(v)1.5 blockade. INTERPRETATION These data support a functional role of K(v)1.5 and K(v)1.3 on activated human DCs and further define the mechanisms by which K(+) channel blockade may act to suppress immune-mediated neurological diseases.
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Affiliation(s)
- Katherine M Mullen
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21287, USA
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127
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Park SA, Lee YC, Ma TZ, Park JA, Han MK, Lee HH, Kim HG, Kwak YG. hKv1.5 channels play a pivotal role in the functions of human alveolar macrophages. Biochem Biophys Res Commun 2006; 346:567-71. [PMID: 16765315 DOI: 10.1016/j.bbrc.2006.05.149] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Accepted: 05/24/2006] [Indexed: 11/25/2022]
Abstract
We examined the pharmacological properties, the molecular identity, and the functional roles of hKv1.5 channel in human alveolar macrophage. Some of outward K(+) current was inhibited by 4-aminopyridine and antisense oligodeoxynucleotides against hKv1.5 mRNA. Consistently, the protein and mRNA expressions of hKv1.5 channel were detected. Furthermore, the phagocytosis and migration of human alveolar macrophages were significantly suppressed when the protein expression of hKv1.5 channel was lowered by the antisense hKv1.5 oligodeoxynucleotides. These results suggest that hKv1.5 channel is expressed in human alveolar macrophages and it plays a role in phagocytosis and migration of the human alveolar macrophage.
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Affiliation(s)
- Seon-Ah Park
- Department of Pharmacology, Chonbuk National University Medical School, Jeonju, Jeonbuk, Republic of Korea
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128
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Abstract
Multiple sclerosis is a chronic inflammatory autoimmune disease of the central nervous system characterized by demyelination and axonal damage that result in disabling neurological deficits. Here the authors explain the rationale for the use of inhibitors of the Kv1.3 K+ channel in immune cells as a therapy for multiple sclerosis and other autoimmune disorders.
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Affiliation(s)
- Christine Beeton
- Department of Physiology and Biophysics, Medical School, University of California, Irvine, 92697, USA
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129
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Arias C, Guizy M, Luque-Ortega JR, Guerrero E, de la Torre BG, Andreu D, Rivas L, Valenzuela C. The induction of NOS2 expression by the hybrid cecropin A-melittin antibiotic peptide CA(1-8)M(1-18) in the monocytic line RAW 264.7 is triggered by a temporary and reversible plasma membrane permeation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1763:110-9. [PMID: 16377003 DOI: 10.1016/j.bbamcr.2005.11.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Revised: 10/25/2005] [Accepted: 11/07/2005] [Indexed: 10/25/2022]
Abstract
There is an increasing awareness of immune cell modulation by antimicrobial peptides. While this process often requires specific receptors for the peptides involved, several reports point out to a receptor-independent process. The cecropin A-melittin hybrid peptide CA(1-8)M(1-18) (KWKLFKKIGIGAVLKVLTTGLPALIS-amide) modifies gene expression in the macrophage line RAW 264.7 in the absence of any previous macrophage priming, suggesting a membrane permeation process. To further analyze the initial steps of this mechanism, we have studied the interaction of the peptide with these cells. Below 2 microM, CA(1-8)M(1-18) causes a concentration-dependent membrane depolarization partially reversible with time. At 2 microM, the accumulation of the SYTOX green vital dye is one half of that achieved with 0.05% Triton X-100. The binding level, as assessed by fluorescein-labeled CA(1-8)M(1-18), varies from 7.7+/-1.2 to 37.4+/-3.9 x 10(6) molecules/cell over a 0.5-4.0 microM concentration range. Electrophysiological experiments with 0.5 microM CA(1-8)M(1-18), a concentration that triggers maximal NOS2 expression and minimal toxicity, show a reversible current induction in the RAW 264.7 plasma membrane that is maintained as far as peptide is present. This activation of the macrophage involves the production of nitric oxide, a metabolite lethal for many pathogens that results from unspecific membrane permeation by antimicrobial peptides, and represents a new mode of action that may open new therapeutic possibilities for these compounds against intracellular pathogens.
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Affiliation(s)
- Cristina Arias
- Institute of Pharmacology and Toxicology, CSIC/UCM, School of Medicine, Universidad Complutense, 28040 Madrid, Spain
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130
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Wang L, Reinach P, Lu L. TNF-alpha promotes cell survival through stimulation of K+ channel and NFkappaB activity in corneal epithelial cells. Exp Cell Res 2005; 311:39-48. [PMID: 16216243 PMCID: PMC1920499 DOI: 10.1016/j.yexcr.2005.08.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Revised: 08/18/2005] [Accepted: 08/18/2005] [Indexed: 01/08/2023]
Abstract
Tumor necrosis factor (TNF-alpha) in various cell types induces either cell death or mitogenesis through different signaling pathways. In the present study, we determined in human corneal epithelial cells how TNF-alpha also promotes cell survival. Human corneal epithelial (HCE) cells were cultured in DMEM/F-12 medium containing 10% FBS. TNF-alpha stimulation induced activation of a voltage-gated K+ channel detected by measuring single channel activity using patch clamp techniques. The effect of TNF-alpha on downstream events included NFkappaB nuclear translocation and increases in DNA binding activities, but did not elicit ERK, JNK, or p38 limb signaling activation. TNF-alpha induced increases in p21 expression resulting in partial cell cycle attenuation in the G1 phase. Cell cycle progression was also mapped by flow cytometer analysis. Blockade of TNF-alpha-induced K+ channel activity effectively prevented NFkappaB nuclear translocation and binding to DNA, diminishing the cell-survival protective effect of TNF-alpha. In conclusion, TNF-alpha promotes survival of HCE cells through sequential stimulation of K+ channel and NFkappaB activities. This response to TNF-alpha is dependent on stimulating K+ channel activity because following suppression of K+ channel activity TNF-alpha failed to activate NFkappaB nuclear translocation and binding to nuclear DNA.
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Affiliation(s)
- Ling Wang
- Division of Molecular Medicine, Harbor-UCLA Medical Center, David Geffen School of Medicine, University of California Los Angeles, 1124 W. Carson Street, C-2, Torrance, CA 90502, USA
| | - Peter Reinach
- Department of Biological Sciences, SUNY College of Optometry, New York, NY 10010, USA
| | - Luo Lu
- Division of Molecular Medicine, Harbor-UCLA Medical Center, David Geffen School of Medicine, University of California Los Angeles, 1124 W. Carson Street, C-2, Torrance, CA 90502, USA
- * Corresponding author. Fax: +1 310 222 3781. E-mail address: (L. Lu)
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131
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Rus H, Pardo CA, Hu L, Darrah E, Cudrici C, Niculescu T, Niculescu F, Mullen KM, Allie R, Guo L, Wulff H, Beeton C, Judge SIV, Kerr DA, Knaus HG, Chandy KG, Calabresi PA. The voltage-gated potassium channel Kv1.3 is highly expressed on inflammatory infiltrates in multiple sclerosis brain. Proc Natl Acad Sci U S A 2005; 102:11094-9. [PMID: 16043714 PMCID: PMC1182417 DOI: 10.1073/pnas.0501770102] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Multiple Sclerosis (MS) is characterized by central nervous system perivenular and parenchymal mononuclear cell infiltrates consisting of activated T cells and macrophages. We recently demonstrated that elevated expression of the voltage-gated potassium channel, Kv1.3, is a functional marker of activated effector memory T (T(EM)) cells in experimental allergic encephalomyelitis and in myelin-specific T cells derived from the peripheral blood of patients with MS. Herein, we show that Kv1.3 is highly expressed in postmortem MS brain inflammatory infiltrates. The expression pattern revealed not only Kv1.3(+) T cells in the perivenular infiltrate but also high expression in the parenchyma of demyelinated MS lesions and both normal appearing gray and white matter. These cells were uniformly chemokine receptor 7 negative (CCR7(-)), consistent with an effector memory phenotype. Using double-labeling immunohistochemistry and confocal microscopy, we demonstrated colocalization of Kv1.3 with CD3, CD4, CD8, and some CD68 cells. The expression patterns mirrored in vitro experiments showing polarization of Kv1.3 to the immunological synapse. Kv1.3 was expressed in low to moderate levels on CCR7(+) central memory T cells from cerebrospinal fluid, but, when these cells were stimulated in vitro, they rapidly became Kv1.3(high)/CCR7(-) T(EM), suggesting that a subset of cerebrospinal fluid cells existed in a primed state ready to become T(EM). These studies provide further rationale for the use of specific Kv1.3 antagonists in MS.
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Affiliation(s)
- Horea Rus
- Department of Neurology, The Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287, USA
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Vicente R, Escalada A, Soler C, Grande M, Celada A, Tamkun MM, Solsona C, Felipe A. Pattern of Kv beta subunit expression in macrophages depends upon proliferation and the mode of activation. THE JOURNAL OF IMMUNOLOGY 2005; 174:4736-44. [PMID: 15814698 DOI: 10.4049/jimmunol.174.8.4736] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Voltage-dependent potassium channels (Kv) in leukocytes are involved in the immune response. In bone marrow-derived macrophages (BMDM), proliferation and activation induce delayed rectifier K+ currents, generated by Kv1.3, via transcriptional, translational, and posttranslational controls. Furthermore, modulatory Kv beta subunits coassociate with Kv alpha subunits, increasing channel diversity and function. In this study we have identified Kv beta subunits in mouse BMDM, studied their regulation during proliferation and activation, and analyzed K+ current parameters influenced by these proteins. BMDM express all isoforms of Kv beta1 (Kv beta1.1, Kv beta1.2, and Kv beta1.3) and Kv beta2 (Kv beta2.1), but not Kv beta4, the alternatively spliced murine Kv beta3 variant. M-CSF-dependent proliferation induced all Kv beta isoforms. However, LPS- and TNF-alpha-induced activation differentially regulated these subunits. Although LPS increased Kv beta1.3, reduced Kv beta1.2, and maintained Kv beta1.1 mRNA levels constant, TNF-alpha up-regulated Kv beta1.1, down-regulated Kv beta1.2, and left Kv beta1.3 expression unchanged. Moreover, in contrast to TNF-alpha, M-CSF- and LPS- up-regulated Kv beta2.1. K+ currents from M-CSF- and LPS-stimulated BMDM exhibited faster inactivation, whereas TNF-alpha increased tau values. Although in M-CSF-stimulated cells the half-inactivation voltage shifted to more positive potentials, the incubation with LPS and TNF-alpha resulted in a hyperpolarizing displacement similar to that in resting BMDM. Furthermore, activation time constants of K+ currents and the kinetics of the tail currents were different depending upon the mode of activation. Our results indicate that differential Kv beta expression modifies the electrical properties of Kv in BMDM, dependent upon proliferation and the mode of activation. This could determine physiologically appropriate surface channel complexes, allowing for greater flexibility in the precise regulation of the immune response.
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Affiliation(s)
- Rubén Vicente
- Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain
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133
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Tsevi I, Vicente R, Grande M, López-Iglesias C, Figueras A, Capellà G, Condom E, Felipe A. KCNQ1/KCNE1 channels during germ-cell differentiation in the rat: expression associated with testis pathologies. J Cell Physiol 2005; 202:400-10. [PMID: 15389592 DOI: 10.1002/jcp.20132] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
KCNQ1/KCNE1 channels are responsible for the Jervell-Lange-Nielsen cardiac syndrome, which is also characterized by congenital deafness. KCNQ1/KCNE1 is crucial for K+ transport in the inner ear. We show that KCNQ1 and KCNE1 are associated in testis and that their expression is closely regulated during development. Both genes were expressed in undifferentiated germ cells in 21-day-old rats and mostly confined to basal immature germ cells in adulthood. Leydig and Sertoli cells were negative. KCNQ1 and KCNE1 were also studied in various germ-cell pathologies. First, in spontaneous unilateral rat testis atrophy, hematoxylin-eosin analysis revealed massive germ-cell aplasia with only Sertoli cells and groups of interstitial Leydig cells. In these samples, KCNQ1 and KCNE1 were not expressed. In human seminoma samples characterized by a proliferation of undifferentiated germ cells, KCNQ1/KCNE1 protein levels were higher than in healthy samples. Our results demonstrate that the expression of KCNQ1 and KCNE1 is associated with early stages of spermatogenesis and with the presence of undifferentiated healthy or neoplastic germ cells. The presence of a K+ rich-fluid in the seminiferous tubule suggests that KCNQ1/KCNE1 is involved in K+ transport, probably during germ-cell development.
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Affiliation(s)
- Irini Tsevi
- Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain
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134
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Argilés JM, Busquets S, Felipe A, López-Soriano FJ. Molecular mechanisms involved in muscle wasting in cancer and ageing: cachexia versus sarcopenia. Int J Biochem Cell Biol 2004; 37:1084-104. [PMID: 15743680 DOI: 10.1016/j.biocel.2004.10.003] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2004] [Revised: 10/05/2004] [Accepted: 10/08/2004] [Indexed: 11/21/2022]
Abstract
The aim of the present review is to summarize and evaluate the different mechanisms and catabolic mediators involved in cancer cachexia and ageing sarcopenia since they may represent targets for future promising clinical investigations. Cancer cachexia is a syndrome characterized by a marked weight loss, anorexia, asthenia and anemia. In fact, many patients who die with advanced cancer suffer from cachexia. The degree of cachexia is inversely correlated with the survival time of the patient and it always implies a poor prognosis. Unfortunately, at the clinical level, cachexia is not treated until the patient suffers from a considerable weight loss and wasting. At this point, the cachectic syndrome is almost irreversible. The cachectic state is often associated with the presence and growth of the tumour and leads to a malnutrition status due to the induction of anorexia. In recent years, age-related diseases and disabilities have become of major health interest and importance. This holds particularly for muscle wasting, also known as sarcopenia, that decreases the quality of life of the geriatric population, increasing morbidity and decreasing life expectancy. The cachectic factors (associated with both depletion of fat stores and muscular tissue) can be divided into two categories: of tumour origin and humoural factors. In conclusion, more research should be devoted to the understanding of muscle wasting mediators, both in cancer and ageing, in particular the identification of common mediators may prove as a good therapeutic strategies for both prevention and treatment of wasting both in disease and during healthy ageing.
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Affiliation(s)
- Josep M Argilés
- Cancer Research Group, Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Diagonal 645, Barcelona 08028, Spain.
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Vicente R, Coma M, Busquets S, Moore-Carrasco R, López-Soriano FJ, Argilés JM, Felipe A. The systemic inflammatory response is involved in the regulation of K+channel expression in brain via TNF-α-dependent and -independent pathways. FEBS Lett 2004; 572:189-94. [PMID: 15304346 DOI: 10.1016/j.febslet.2004.07.030] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2004] [Revised: 07/16/2004] [Accepted: 07/16/2004] [Indexed: 11/28/2022]
Abstract
TNF-alpha, generated during the systemic inflammatory response, triggers a wide range of biological activities that mediate the neurologic manifestations associated with cancer and infection. Since this cytokine regulates ion channels in vitro (especially Kv1.3 and Kir2.1), we aimed to study Kv1.3 and Kir2.1 expression in brain in response to in vivo systemic inflammation. Cancer-induced cachexia and LPS administration increased plasma TNF-alpha. Kv1.3 and Kir2.1 expression was impaired in brain during cancer cachexia. However, LPS treatment induced Kv1.3 and downregulated Kir2.1 expression, and TNF-alpha administration mimicked these results. Experiments using TNF-alpha double receptor knockout mice demonstrated that the systemic inflammatory response mediates K(+) channel regulation in brain via TNF-alpha-dependent and -independent redundant pathways. In summary, distinct neurological alterations associated with systemic inflammation may result from the interaction of various cytokine pathways tuning ion channel expression in response to neurophysiological and neuroimmunological processes.
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MESH Headings
- Animals
- Antigens, CD/genetics
- Antigens, CD/physiology
- Brain/physiology
- Brain/physiopathology
- Cachexia/genetics
- Cachexia/physiopathology
- Female
- Inflammation/genetics
- Inflammation/physiopathology
- Kv1.3 Potassium Channel
- Liver Neoplasms, Experimental
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Potassium Channels/physiology
- Potassium Channels, Inwardly Rectifying/physiology
- Potassium Channels, Voltage-Gated
- Rats
- Rats, Wistar
- Receptors, Tumor Necrosis Factor/deficiency
- Receptors, Tumor Necrosis Factor/genetics
- Receptors, Tumor Necrosis Factor/physiology
- Receptors, Tumor Necrosis Factor, Type I
- Receptors, Tumor Necrosis Factor, Type II
- Tumor Necrosis Factor-alpha/physiology
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Affiliation(s)
- Rubén Vicente
- Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Avda. Diagonal 645, E-08028 Barcelona, Spain
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