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Scepanovic G, Fernandez-Gonzalez R. Should I shrink or should I grow: cell size changes in tissue morphogenesis. Genome 2024; 67:125-138. [PMID: 38198661 DOI: 10.1139/gen-2023-0091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
Cells change shape, move, divide, and die to sculpt tissues. Common to all these cell behaviours are cell size changes, which have recently emerged as key contributors to tissue morphogenesis. Cells can change their mass-the number of macromolecules they contain-or their volume-the space they encompass. Changes in cell mass and volume occur through different molecular mechanisms and at different timescales, slow for changes in mass and rapid for changes in volume. Therefore, changes in cell mass and cell volume, which are often linked, contribute to the development and shaping of tissues in different ways. Here, we review the molecular mechanisms by which cells can control and alter their size, and we discuss how changes in cell mass and volume contribute to tissue morphogenesis. The role that cell size control plays in developing embryos is only starting to be elucidated. Research on the signals that control cell size will illuminate our understanding of the cellular and molecular mechanisms that drive tissue morphogenesis.
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Affiliation(s)
- Gordana Scepanovic
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
- Ted Rogers Centre for Heart Research, University of Toronto, Toronto, ON M5G 1M1, Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Rodrigo Fernandez-Gonzalez
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
- Ted Rogers Centre for Heart Research, University of Toronto, Toronto, ON M5G 1M1, Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada
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2
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Apoptosis or Antiapoptosis? Interrupted Regulated Cell Death of Host Cells by Ascovirus Infection In Vitro. mBio 2023; 14:e0311922. [PMID: 36744941 PMCID: PMC9973268 DOI: 10.1128/mbio.03119-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Ascoviruses are insect-specific viruses thought to utilize the cellular apoptotic processes of host larvae to produce numerous virion-containing vesicles. In this study, we first determined the biochemical characteristics of ascovirus-infected, in vitro-cultured insect cells and the possible antiapoptotic capacity of ascovirus-infected insect cells. The results indicated that the ascovirus infection in the first 24 h was different from the infection from 48 h to the later infection stages. In the early infection stage, the Spodoptera exigua host cells had high membrane permeability and cleaved gasdermin D (GSDMD) but uncleaved Casp-6 (SeCasp-6). In contrast, the later infection stage had no such increased membrane permeability and had cleaved SeCasp-6. Four different chemicals were used to induce apoptosis at different stages of ascovirus infection: hydrogen peroxide (H2O2) and actinomycin D (ActD) had similar effects on the ascovirus-infected cells, whereas cMYC inhibitors and tumor necrosis factor alpha (TNF-α) plus SM-164 apoptosis inducers (T/S) had similar effects on infected cells. The former two inducers inhibited viral DNA replication in most situations, while the latter two inducers inhibited viral DNA replication in the early stage of infection but promoted viral DNA replication in the later infection stage. Furthermore, immunoblotting assays verified that T/S treatment could increase the expression levels of viral major capsid protein (MCP) and the host inhibitor of apoptosis protein (SeIAP). Coimmunoprecipitation assays revealed interaction between SeIAP and SeCasps, but this interaction was disturbed in ascovirus-infected cells. This study details the in vitro infection process of ascovirus, indicating the utilization of pyroptosis for antiapoptosis cytopathology. IMPORTANCE Clarifying the relationship between different types of viral infections and host regulation of cell death (RCD) can provide insights into the interaction between viruses and host cells. Ascoviruses are insect-specific viruses with apoptosis-utilizing-like infection cytopathology. However, RCD does not only include apoptosis, and while in our previous transmission electron microscopic observations, ascovirus-infected cells did not show typical apoptotic characteristics (unpublished data), in this study, they did show increased membrane permeability. These results indicate that the cytopathology of ascovirus infection is a complex process in which the virus manipulates host RCD. The RCD of insect cells is quite different from that of mammals, and studies on the former are many fewer than those on the latter, especially in the case of RCD in lepidopteran insects. Our results will lay a foundation for understanding the RCD of lepidopteran insects and its function in the process of insect virus infection.
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Checchetto V, Leanza L, De Stefani D, Rizzuto R, Gulbins E, Szabo I. Mitochondrial K + channels and their implications for disease mechanisms. Pharmacol Ther 2021; 227:107874. [PMID: 33930454 DOI: 10.1016/j.pharmthera.2021.107874] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 04/12/2021] [Indexed: 02/06/2023]
Abstract
The field of mitochondrial ion channels underwent a rapid development during the last decade, thanks to the molecular identification of some of the nuclear-encoded organelle channels and to advances in strategies allowing specific pharmacological targeting of these proteins. Thereby, genetic tools and specific drugs aided definition of the relevance of several mitochondrial channels both in physiological as well as pathological conditions. Unfortunately, in the case of mitochondrial K+ channels, efforts of genetic manipulation provided only limited results, due to their dual localization to mitochondria and to plasma membrane in most cases. Although the impact of mitochondrial K+ channels on human diseases is still far from being genuinely understood, pre-clinical data strongly argue for their substantial role in the context of several pathologies, including cardiovascular and neurodegenerative diseases as well as cancer. Importantly, these channels are druggable targets, and their in-depth investigation could thus pave the way to the development of innovative small molecules with huge therapeutic potential. In the present review we summarize the available experimental evidence that mechanistically link mitochondrial potassium channels to the above pathologies and underline the possibility of exploiting them for therapy.
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Affiliation(s)
| | - Luigi Leanza
- Department of Biology, University of Padova, Italy
| | | | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, Italy
| | - Erich Gulbins
- Department of Molecular Biology, University of Duisburg-Essen, Germany
| | - Ildiko Szabo
- Department of Biology, University of Padova, Italy; CNR Institute of Neurosciences, Italy.
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4
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Bachmann M, Li W, Edwards MJ, Ahmad SA, Patel S, Szabo I, Gulbins E. Voltage-Gated Potassium Channels as Regulators of Cell Death. Front Cell Dev Biol 2020; 8:611853. [PMID: 33381507 PMCID: PMC7767978 DOI: 10.3389/fcell.2020.611853] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/23/2020] [Indexed: 12/11/2022] Open
Abstract
Ion channels allow the flux of specific ions across biological membranes, thereby determining ion homeostasis within the cells. Voltage-gated potassium-selective ion channels crucially contribute to the setting of the plasma membrane potential, to volume regulation and to the physiologically relevant modulation of intracellular potassium concentration. In turn, these factors affect cell cycle progression, proliferation and apoptosis. The present review summarizes our current knowledge about the involvement of various voltage-gated channels of the Kv family in the above processes and discusses the possibility of their pharmacological targeting in the context of cancer with special emphasis on Kv1.1, Kv1.3, Kv1.5, Kv2.1, Kv10.1, and Kv11.1.
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Affiliation(s)
- Magdalena Bachmann
- Department of Biology, University of Padova, Padua, Italy.,Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Weiwei Li
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Michael J Edwards
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Syed A Ahmad
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Sameer Patel
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Ildiko Szabo
- Department of Biology, University of Padova, Padua, Italy.,Consiglio Nazionale delle Ricerche Institute of Neuroscience, Padua, Italy
| | - Erich Gulbins
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States.,Department of Molecular Biology, University of Duisburg-Essen, Essen, Germany
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5
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Yu H, Li ZQ, Ou-Yang YY, Huang GH. Identification of four caspase genes from Spodoptera exigua (Lepidoptera: Noctuidae) and their regulations toward different apoptotic stimulations. INSECT SCIENCE 2020; 27:1158-1172. [PMID: 31793737 DOI: 10.1111/1744-7917.12741] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 11/09/2019] [Accepted: 11/20/2019] [Indexed: 06/10/2023]
Abstract
Apoptosis plays critical roles in multiple biological processes in multicellular organisms. Caspases are known as important participators and regulators of apoptosis. Here, four novel caspase genes of Spodoptera exigua were cloned and characterized, which were designated as SeCasp-1, SeCasp-6, SeCasp-7 and SeCasp-8. Analysis of the putative encoded protein sequences of these SeCasps indicated that SeCasp-1 and SeCasp-7 were possible homologs of executor caspases; SeCasp-8 was a possible homolog of initiator caspases; and SeCasp-6 was a unique caspase of S. exigua that shares low similarity with all the identified insect caspases. Based on baculovirus expression system analyses, SeCasp-1 exhibited similar caspase activity to human caspase-1, -3, -4, -6, -8 and -9; SeCasp-6 presented similar caspase activity to human caspase-2, -3, -4, -6, -8 and -9; SeCasp-7 exhibited similar caspase activity to human caspase-2, -3 and -6; and SeCasp-8 presented similar caspase activity only to human caspase-8. Induction with different chemicals revealed that SeCasp-1 showed extreme upregulation after 24 h in the treated fat body cell line (IOZCAS-Spex-II) of S. exigua. Developmental expression analysis revealed that SeCasp-1 was highly transcribed in the larval stages, while SeCasp-6, SeCasp-7, SeCasp-8 were down-regulated. The in vivo detection of the relative expression levels of SeCasps in S. eixgua larvae inoculated with different pathogens suggested that SeCasp-1 was sensitive to Bacillus thuringiensis infection and that SeCasp-6 was sensitive to baculovirus infection. SeCasp-7 and SeCasp-8 showed slight changes under either in vitro chemical apoptosis induction or in vivo pathogen infection.
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Affiliation(s)
- Huan Yu
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, China
- College of Plant Protection, Hunan Agricultural University, Changsha, China
| | - Zi-Qi Li
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, China
- College of Plant Protection, Hunan Agricultural University, Changsha, China
| | - Yi-Yi Ou-Yang
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, China
- College of Plant Protection, Hunan Agricultural University, Changsha, China
| | - Guo-Hua Huang
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, China
- College of Plant Protection, Hunan Agricultural University, Changsha, China
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6
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Ozyigit II. Gene transfer to plants by electroporation: methods and applications. Mol Biol Rep 2020; 47:3195-3210. [PMID: 32242300 DOI: 10.1007/s11033-020-05343-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 02/22/2020] [Indexed: 01/09/2023]
Abstract
Developing gene transfer technologies enables the genetic manipulation of the living organisms more efficiently. The methods used for gene transfer fall into two main categories; natural and artificial transformation. The natural methods include the conjugation, transposition, bacterial transformation as well as phage and retroviral transductions, contain the physical methods whereas the artificial methods can physically alter and transfer genes from one to another organisms' cell using, for instance, biolistic transformation, micro- and macroinjection, and protoplast fusion etc. The artificial gene transformation can also be conducted through chemical methods which include calcium phosphate-mediated, polyethylene glycol-mediated, DEAE-Dextran, and liposome-mediated transfers. Electrical methods are also artificial ways to transfer genes that can be done by electroporation and electrofusion. Comparatively, among all the above-mentioned methods, electroporation is being widely used owing to its high efficiency and broader applicability. Electroporation is an electrical transformation method by which transient electropores are produced in the cell membranes. Based on the applications, process can be either reversible where electropores in membrane are resealable and cells preserve the vitality or irreversible where membrane is not able to reseal, and cell eventually dies. This problem can be minimized by developing numerical models to iteratively optimize the field homogeneity considering the cell size, shape, number, and electrode positions supplemented by real-time measurements. In modern biotechnology, numerical methods have been used in electrotransformation, electroporation-based inactivation, electroextraction, and electroporative biomass drying. Moreover, current applications of electroporation also point to some other uncovered potentials for various exploitations in future.
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Affiliation(s)
- Ibrahim Ilker Ozyigit
- Department of Biology, Faculty of Science and Arts, Marmara University, Goztepe, 34722, Istanbul, Turkey. .,Department of Biology, Faculty of Science, Kyrgyz-Turkish Manas University, 720038, Bishkek, Kyrgyzstan.
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7
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Simonis A, Schubert-Unkmeir A. The role of acid sphingomyelinase and modulation of sphingolipid metabolism in bacterial infection. Biol Chem 2019; 399:1135-1146. [PMID: 29924727 DOI: 10.1515/hsz-2018-0200] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 06/14/2018] [Indexed: 01/01/2023]
Abstract
Acid sphingomyelinase (ASM) is a key enzyme in sphingolipid metabolism that converts sphingomyelin to ceramide, thereby modulating membrane structures and signal transduction. Bacterial pathogens can manipulate ASM activity and function, and use host sphingolipids during multiple steps of their infection process. An increase in ceramides upon infection results in the formation of ceramide-enriched membrane platforms that serve to cluster receptor molecules and organize intracellular signaling molecules, thus facilitating bacterial uptake. In this review, we focus on how extracellular bacterial pathogens target ASM and modulate membrane properties and signaling pathways to gain entry into eukaryotic cells or induce cell death. We describe how intracellular pathogens interfere with the intralysosomal functions of ASM to favor replication and survival. In addition, bacteria utilize their own sphingomyelinases as virulence factors to modulate sphingolipid metabolism. The potential of ASM as a target for treating bacterial infections is also discussed.
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Affiliation(s)
- Alexander Simonis
- Division of Hematology, University Hospital Zurich, Rämistrasse 100, 8091 Zürich, Switzerland
| | - Alexandra Schubert-Unkmeir
- Institute of Hygiene and Microbiology, University of Würzburg, Josef-Schneider-Straße 2, D-97080 Würzburg, Germany
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8
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Implication of Voltage-Gated Potassium Channels in Neoplastic Cell Proliferation. Cancers (Basel) 2019; 11:cancers11030287. [PMID: 30823672 PMCID: PMC6468671 DOI: 10.3390/cancers11030287] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 02/21/2019] [Accepted: 02/24/2019] [Indexed: 12/12/2022] Open
Abstract
Voltage-gated potassium channels (Kv) are the largest group of ion channels. Kv are involved in controlling the resting potential and action potential duration in the heart and brain. Additionally, these proteins participate in cell cycle progression as well as in several other important features in mammalian cell physiology, such as activation, differentiation, apoptosis, and cell volume control. Therefore, Kv remarkably participate in the cell function by balancing responses. The implication of Kv in physiological and pathophysiological cell growth is the subject of study, as Kv are proposed as therapeutic targets for tumor regression. Though it is widely accepted that Kv channels control proliferation by allowing cell cycle progression, their role is controversial. Kv expression is altered in many cancers, and their participation, as well as their use as tumor markers, is worthy of effort. There is an ever-growing list of Kv that remodel during tumorigenesis. This review focuses on the actual knowledge of Kv channel expression and their relationship with neoplastic proliferation. In this work, we provide an update of what is currently known about these proteins, thereby paving the way for a more precise understanding of the participation of Kv during cancer development.
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9
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Javadov S, Chapa-Dubocq X, Makarov V. Different approaches to modeling analysis of mitochondrial swelling. Mitochondrion 2017; 38:58-70. [PMID: 28802667 DOI: 10.1016/j.mito.2017.08.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/21/2017] [Accepted: 08/08/2017] [Indexed: 12/11/2022]
Abstract
Mitochondria are critical players involved in both cell life and death through multiple pathways. Structural integrity, metabolism and function of mitochondria are regulated by matrix volume due to physiological changes of ion homeostasis in cellular cytoplasm and mitochondria. Ca2+ and K+ presumably play a critical role in physiological and pathological swelling of mitochondria when increased uptake (influx)/decreased release (efflux) of these ions enhances osmotic pressure accompanied by high water accumulation in the matrix. Changes in the matrix volume in the physiological range have a stimulatory effect on electron transfer chain and oxidative phosphorylation to satisfy metabolic requirements of the cell. However, excessive matrix swelling associated with the sustained opening of mitochondrial permeability transition pores (PTP) and other PTP-independent mechanisms compromises mitochondrial function and integrity leading to cell death. The mechanisms of transition from reversible (physiological) to irreversible (pathological) swelling of mitochondria remain unknown. Mitochondrial swelling is involved in the pathogenesis of many human diseases such as neurodegenerative and cardiovascular diseases. Therefore, modeling analysis of the swelling process is important for understanding the mechanisms of cell dysfunction. This review attempts to describe the role of mitochondrial swelling in cell life and death and the main mechanisms involved in the maintenance of ion homeostasis and swelling. The review also summarizes and discusses different kinetic models and approaches that can be useful for the development of new models for better simulation and prediction of in vivo mitochondrial swelling.
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Affiliation(s)
- Sabzali Javadov
- Department of Physiology, School of Medicine, University of Puerto Rico, San Juan, PR, USA.
| | - Xavier Chapa-Dubocq
- Department of Physiology, School of Medicine, University of Puerto Rico, San Juan, PR, USA
| | - Vladimir Makarov
- Department of Physics, Rio Piedras Campus, University of Puerto Rico, San Juan, PR, USA
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10
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Liu H, Liu J, Xu E, Tu G, Guo M, Liang S, Xiong H. Human immunodeficiency virus protein Tat induces oligodendrocyte injury by enhancing outward K + current conducted by K V1.3. Neurobiol Dis 2016; 97:1-10. [PMID: 27816768 DOI: 10.1016/j.nbd.2016.10.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/21/2016] [Accepted: 10/30/2016] [Indexed: 12/28/2022] Open
Abstract
Brain white matter damage is frequently detected in patients infected with human immunodeficiency virus type 1 (HIV-1). White matter is composed of neuronal axons sheathed by oligodendrocytes (Ols), the myelin-forming cells in central nervous system. Ols are susceptible to HIV-1 viral trans-activator of transcription (Tat) and injury of Ols results in myelin sheath damage. It has been demonstrated that activation of voltage-gated K+ (KV) channels induces cell apoptosis and Ols predominantly express K+ channel KV1.3. It is our hypothesis that Tat injures Ols via activation of KV1.3. To test this hypothesis, we studied the involvement of KV1.3 in Tat-induced Ol/myelin injury both in vitro and ex vivo. Application of Tat to primary rat Ol cultures enhanced whole-cell KV1.3 current recorded under voltage clamp configuration and confirmed by specific KV1.3 antagonists Margatoxin (MgTx) and 5-(4-phenoxybutoxy) psoralen (PAP). The Tat enhancement of KV1.3 current was associated with Tat-induced Ol apoptosis, which was blocked by MgTx and PAP or by siRNA knockdown of KV1.3 gene. The Tat-induced Ol injury was validated in cultured rat brain slices, particularly in corpus callosum and striatum, that incubation of the slices with Tat resulted in myelin damage and reduction of myelin basic protein which were also blocked by aforementioned KV1.3 antagonists. Further studies revealed that Tat interacts with KV1.3 as determined by protein pull-down of recombinant GST-Tat with KV1.3 expressed in rat brains and HEK293 cells. Such protein-protein interaction may alter channel protein phosphorylation, resultant channel activity and consequent Ol/myelin injury. Taken together, these results demonstrate an involvement of KV1.3 in Tat- induced Ol/myelin injury, a potential mechanism for the pathogenesis of HIV-1-associated white matter damage.
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Affiliation(s)
- Han Liu
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | - Jianuo Liu
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | - Enquan Xu
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | - Guihua Tu
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | - Minglei Guo
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | - Shangdong Liang
- Department of Physiology, College of Basic Medical Sciences, Nanchang University, Nanchang, Jiangxi, People's Republic of China
| | - Huangui Xiong
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA.
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Functional Interactions between BK Caα-Subunit and Annexin A5: Implications in Apoptosis. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:1607092. [PMID: 27738490 PMCID: PMC5055951 DOI: 10.1155/2016/1607092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 07/04/2016] [Accepted: 07/10/2016] [Indexed: 12/26/2022]
Abstract
Proteomic studies have suggested a biochemical interaction between α subunit of the large conductance, voltage- and Ca2+-activated potassium channel (BKCaα), and annexin A5 (ANXA5), which we verify here by coimmunoprecipitation and double labelling immunocytochemistry. The observation that annexin is flipped to the outer membrane leaflet of the plasma membrane during apoptosis, together with the knowledge that the intracellular C-terminal of BKCaα contains both Ca2+-binding and a putative annexin-binding motif, prompted us to investigate the functional consequences of this protein partnership to cell death. Membrane biotinylation demonstrated that ANXA5 was flipped to the outer membrane leaflet of HEK 293 cells early in serum deprivation-evoked apoptosis. As expected, serum deprivation caused caspase-3/7 activation and this was accentuated in BKCaα expressing HEK 293 cells. The functional consequences of ANXA5 partnership with BKCaα were striking, with ANXA5 knockdown causing an increase and ANXA5 overexpression causing a decrease, in single BKCa channel Ca2+-sensitivity, measured in inside-out membrane patches by patch-clamp. Taken together, these data suggest a novel model of the early stages of apoptosis where membrane flippage results in removal of the inhibitory effect of ANXA5 on K+ channel activity with the consequent amplification of Ca2+ influx and augmented activation of caspases.
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Pérez-Verdaguer M, Capera J, Serrano-Novillo C, Estadella I, Sastre D, Felipe A. The voltage-gated potassium channel Kv1.3 is a promising multitherapeutic target against human pathologies. Expert Opin Ther Targets 2015; 20:577-91. [DOI: 10.1517/14728222.2016.1112792] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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13
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Wang F, Liu X, Liu C, Liu Z, Sun L. Effects of antibiotic antitumor drugs on nucleotide levels in cultured tumor cells: an exploratory method to distinguish the mechanisms of antitumor drug action based on targeted metabolomics. Acta Pharm Sin B 2015; 5:223-30. [PMID: 26579450 PMCID: PMC4629260 DOI: 10.1016/j.apsb.2015.03.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 12/19/2014] [Accepted: 03/14/2015] [Indexed: 12/29/2022] Open
Abstract
Nucleotide pools in mammalian cells change due to the influence of antitumor drugs, which may help in evaluating the drug effect and understanding the mechanism of drug action. In this study, an ion-pair RP-HPLC method was used for a simple, sensitive and simultaneous determination of the levels of 12 nucleotides in mammalian cells treated with antibiotic antitumor drugs (daunorubicin, epirubicin and dactinomycin D). Through the use of this targeted metabolomics approach to find potential biomarkers, UTP and ATP were verified to be the most appropriate biomarkers. Moreover, a holistic statistical approach was put forward to develop a model which could distinguish 4 categories of drugs with different mechanisms of action. This model can be further validated by evaluating drugs with different mechanisms of action. This targeted metabolomics study may provide a novel approach to predict the mechanism of action of antitumor drugs.
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Key Words
- ADP, adenosine diphosphate
- AMP, adenosine monophosphate
- ANOVA, analysis of variance
- ATP, adenosine triphosphate
- AUC, area under the curve
- Antibiotic anticancer drugs
- CDP, cytidine diphosphate
- CTP, cytidine triphosphate
- DMEM, Dulbecco׳s modified eagle׳s cell culture media
- DMSO, dimethyl sulfoxide
- DNA, deoxyribonucleic acid
- EC, energy charge
- EDTA, ethylene diamine tetra-acetic acid
- FCS, fetal calf serum
- GDP, guanosine diphosphate
- GMP, guanosine monophosphate
- GTP, guanosine triphosphate
- HEPES, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- Ion-pair HPLC
- MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide
- Mechanisms of antitumor drug action
- Nucleotides
- PBS, phosphate buffered saline
- PCA, principal component analysis
- Potential biomarkers
- Principal component analysis
- RNA, ribonucleic acid
- ROC, receiver operating characteristic
- RPMI-1640, Roswell Park Memorial Institute-1640
- TBAHS, tetrabutylammonium hydrogen sulfate
- TCA, trichloroacetic acid
- Targeted metabolomics analysis
- Tumor cells
- UDP, uridine diphosphate
- UTP, uridine triphosphate
- dATP, deoxyadenosine triphosphate
- dCDP, deoxycytidine diphosphate
- dCTP, deoxycytidine triphosphate
- dGMP, deoxyribonucleic monophosphate
- dGTP, deoxyguanosine triphosphate
- dUDP, deoxyuridine diphpsphate
- dUTP, deoxyuridine triphosphate
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Affiliation(s)
- Fang Wang
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Xi Liu
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Cuichai Liu
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Zheng Liu
- School of Life Science and Bio-pharmaceutics Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Lixin Sun
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China
- Corresponding author. Tel.: +86 24 23986365; fax: +86 24 23986259.
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Placing ion channels into a signaling network of T cells: from maturing thymocytes to healthy T lymphocytes or leukemic T lymphoblasts. BIOMED RESEARCH INTERNATIONAL 2015; 2015:750203. [PMID: 25866806 PMCID: PMC4383400 DOI: 10.1155/2015/750203] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 09/19/2014] [Indexed: 12/20/2022]
Abstract
T leukemogenesis is a multistep process, where the genetic errors during T cell maturation cause the healthy progenitor to convert into the leukemic precursor that lost its ability to differentiate but possesses high potential for proliferation, self-renewal, and migration. A new misdirecting "leukemogenic" signaling network appears, composed by three types of participants which are encoded by (1) genes implicated in determined stages of T cell development but deregulated by translocations or mutations, (2) genes which normally do not participate in T cell development but are upregulated, and (3) nondifferentially expressed genes which become highly interconnected with genes expressed differentially. It appears that each of three groups may contain genes coding ion channels. In T cells, ion channels are implicated in regulation of cell cycle progression, differentiation, activation, migration, and cell death. In the present review we are going to reveal a relationship between different genetic defects, which drive the T cell neoplasias, with calcium signaling and ion channels. We suggest that changes in regulation of various ion channels in different types of the T leukemias may provide the intracellular ion microenvironment favorable to maintain self-renewal capacity, arrest differentiation, induce proliferation, and enhance motility.
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Live fluorescence and transmission-through-dye microscopic study of actinomycin D-induced apoptosis and apoptotic volume decrease. Apoptosis 2014; 18:521-32. [PMID: 23325449 DOI: 10.1007/s10495-013-0804-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The effect of actinomycin D on HeLa cells was studied by live fluorescence and transmission-through-dye microscopy-a recently developed technique that permits volume measurements in live cells. In particular, it is well suited for the observation and quantification of the apoptotic volume decrease (AVD), which is widely viewed as an essential feature of apoptosis. The main results from our study are as follows. (1) Apoptosis caused in HeLa cells by actinomycin D proceeds in two morphologically distinct stages: the early stage is characterized by extensive blebbing, and the late stage by a more compact shape. The loss of mitochondrial membrane potential occurs at about the same time as blebbing, and chromatin condensation follows 30-90 min later. Caspase-3 and 7 become activated during the late stage. (2) Because blebbing occurs before activation of caspase-3, it has to be initiated by a different mechanism. Although blebbing is one of the earliest observable changes, it can be selectively inhibited without affecting other apoptotic reactions. (3) The majority of cells experience a temporary volume increase after the appearance of blebs. Eventually, AVD takes over and the cells shrink by approximately 40 % of their initial volume; the volume loss becomes noticeable at the end of the blebbing phase and continues through the late stage. Sometimes, at the end of long incubations, shrinkage gives way to swelling, possibly indicating secondary necrosis. (4) Both early and late apoptosis are accompanied by intracellular accumulation of Na(+), while low-sodium medium prevents apoptosis. Except for a partial protective effect of quinine, all of the tested blockers of Na(+), K(+) and Cl(-) channels failed to prevent apoptosis or AVD.
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Abstract
Potassium channels are transmembrane proteins that selectively facilitate the flow of potassium ions down an electrochemical gradient. These molecules have been studied in great detail in the context of cell excitability, but their roles in less cell type-specific functions, such as cell proliferation, angiogenesis or cell migration, have only recently been assessed. Moreover, the importance of these channels for tumour biology has become evident. This, coupled with the fact that they are accessible proteins and that their pharmacology is well characterized, has increased the interest in investigating potassium channels as therapeutic targets in cancer patients.
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Affiliation(s)
- Luis A Pardo
- Oncophysiology Group, Max-Planck-Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
| | - Walter Stühmer
- Department of Molecular Biology of Neuronal Signals, Max-Planck-Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
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Makino A, Firth AL, Yuan JXJ. Endothelial and smooth muscle cell ion channels in pulmonary vasoconstriction and vascular remodeling. Compr Physiol 2013; 1:1555-602. [PMID: 23733654 DOI: 10.1002/cphy.c100023] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The pulmonary circulation is a low resistance and low pressure system. Sustained pulmonary vasoconstriction and excessive vascular remodeling often occur under pathophysiological conditions such as in patients with pulmonary hypertension. Pulmonary vasoconstriction is a consequence of smooth muscle contraction. Many factors released from the endothelium contribute to regulating pulmonary vascular tone, while the extracellular matrix in the adventitia is the major determinant of vascular wall compliance. Pulmonary vascular remodeling is characterized by adventitial and medial hypertrophy due to fibroblast and smooth muscle cell proliferation, neointimal proliferation, intimal, and plexiform lesions that obliterate the lumen, muscularization of precapillary arterioles, and in situ thrombosis. A rise in cytosolic free Ca(2+) concentration ([Ca(2+)]cyt) in pulmonary artery smooth muscle cells (PASMC) is a major trigger for pulmonary vasoconstriction, while increased release of mitogenic factors, upregulation (or downregulation) of ion channels and transporters, and abnormalities in intracellular signaling cascades are key to the remodeling of the pulmonary vasculature. Changes in the expression, function, and regulation of ion channels in PASMC and pulmonary arterial endothelial cells play an important role in the regulation of vascular tone and development of vascular remodeling. This article will focus on describing the ion channels and transporters that are involved in the regulation of pulmonary vascular function and structure and illustrating the potential pathogenic role of ion channels and transporters in the development of pulmonary vascular disease.
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Affiliation(s)
- Ayako Makino
- Department of Medicine, The University of Illinois at Chicago, Chicago, Illinois, USA
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Comes N, Bielanska J, Vallejo-Gracia A, Serrano-Albarrás A, Marruecos L, Gómez D, Soler C, Condom E, Ramón Y Cajal S, Hernández-Losa J, Ferreres JC, Felipe A. The voltage-dependent K(+) channels Kv1.3 and Kv1.5 in human cancer. Front Physiol 2013; 4:283. [PMID: 24133455 PMCID: PMC3794381 DOI: 10.3389/fphys.2013.00283] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 09/18/2013] [Indexed: 11/20/2022] Open
Abstract
Voltage-dependent K+ channels (Kv) are involved in a number of physiological processes, including immunomodulation, cell volume regulation, apoptosis as well as differentiation. Some Kv channels participate in the proliferation and migration of normal and tumor cells, contributing to metastasis. Altered expression of Kv1.3 and Kv1.5 channels has been found in several types of tumors and cancer cells. In general, while the expression of Kv1.3 apparently exhibits no clear pattern, Kv1.5 is induced in many of the analyzed metastatic tissues. Interestingly, evidence indicates that Kv1.5 channel shows inversed correlation with malignancy in some gliomas and non-Hodgkin's lymphomas. However, Kv1.3 and Kv1.5 are similarly remodeled in some cancers. For instance, expression of Kv1.3 and Kv1.5 correlates with a certain grade of tumorigenicity in muscle sarcomas. Differential remodeling of Kv1.3 and Kv1.5 expression in human cancers may indicate their role in tumor growth and their importance as potential tumor markers. However, despite of this increasing body of information, which considers Kv1.3 and Kv1.5 as emerging tumoral markers, further research must be performed to reach any conclusion. In this review, we summarize what it has been lately documented about Kv1.3 and Kv1.5 channels in human cancer.
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Affiliation(s)
- Núria Comes
- Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina, Universitat de Barcelona Barcelona, Spain
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Wang T, Lee MH, Choi E, Pardo-Villamizar CA, Lee SB, Yang IH, Calabresi PA, Nath A. Granzyme B-induced neurotoxicity is mediated via activation of PAR-1 receptor and Kv1.3 channel. PLoS One 2012; 7:e43950. [PMID: 22952817 PMCID: PMC3430617 DOI: 10.1371/journal.pone.0043950] [Citation(s) in RCA: 37] [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: 05/02/2012] [Accepted: 07/27/2012] [Indexed: 11/19/2022] Open
Abstract
Increasing evidence supports a critical role of T cells in neurodegeneration associated with acute and subacute brain inflammatory disorders. Granzyme B (GrB), released by activated T cells, is a cytotoxic proteinase which may induce perforin-independent neurotoxicity. Here, we studied the mechanism of perforin-independent GrB toxicity by treating primary cultured human neuronal cells with recombinant GrB. GrBactivated the protease-activated receptor (PAR)-1 receptor on the neuronal cell surface leading to decreased intracellular cyclic AMP levels. This was followed by increased expression and translocation of the voltage gated potassium channel, Kv1.3 to the neuronal cell membrane. Similar expression of Kv1.3 was also seen in neurons of the cerebral cortex adjacent to active inflammatory lesions in patients with multiple sclerosis. Kv1.3 expression was followed by activation of Notch-1 resulting in neurotoxicity. Blocking PAR-1, Kv1.3 or Notch-1 activation using specific pharmacological inhibitors or siRNAs prevented GrB-induced neurotoxicity. Furthermore, clofazimine protected against GrB-induced neurotoxicity in rat hippocampus, in vivo. These observations indicate that GrB released from T cells induced neurotoxicity by interacting with the membrane bound Gi-coupled PAR-1 receptor and subsequently activated Kv1.3 and Notch-1. These pathways provide novel targets to treat T cell-mediated neuroinflammatory disorders. Kv1.3 is of particular interest since it is expressed on the cell surface, only under pathological circumstances, and early in the cascade of events making it an attractive therapeutic target.
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Affiliation(s)
- Tongguang Wang
- Section of Infections of the Nervous System, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Myoung-Hwa Lee
- Section of Infections of the Nervous System, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Elliot Choi
- Section of Infections of the Nervous System, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | | | - Sung Bin Lee
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - In Hong Yang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
- Singapore Institute for Nanotechnology, National University of Singapore, Singapore, Singapore
| | - Peter A. Calabresi
- Department of Neurology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Avindra Nath
- Department of Neurology, Johns Hopkins University, Baltimore, Maryland, United States of America
- Section of Infections of the Nervous System, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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Nazari M, Emamzadeh R, Hosseinkhani S, Cevenini L, Michelini E, Roda A. Renilla luciferase-labeled Annexin V: a new probe for detection of apoptotic cells. Analyst 2012; 137:5062-70. [DOI: 10.1039/c2an35741k] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Gopalani NK, Meena RN, Prasad DN, Ilavazhagan G, Sharma M. Cooperativity between inhibition of cytosolic K+ efflux and AMPK activation during suppression of hypoxia-induced cellular apoptosis. Int J Biochem Cell Biol 2011; 44:211-23. [PMID: 22064248 DOI: 10.1016/j.biocel.2011.10.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 10/13/2011] [Accepted: 10/25/2011] [Indexed: 02/05/2023]
Abstract
Cellular potassium homeostasis has recently emerged as a critical regulator of apoptosis in response to variety of stimuli. However, functional hierarchy of this phenomenon in the apoptotic cascade and therefore, its significance as a pathway for intervention is not fully established. Chronic hypoxia, a known threat to cell survival, also modulates cellular potassium homeostasis. In this study, we tested if hypoxia-induced apoptosis in lymphocytes can be prevented by modulating cellular K+ homeostasis. We observed that chronic hypoxia accelerated the rate of apoptosis in resting murine splenocytes concomitant with cytosolic K+ efflux. We tested several modalities including elevated extracellular potassium besides various K+ channel inhibitors to curtail hypoxia-induced K+ efflux and interestingly, established that the supplementation of KCl in extracellular medium was most effective in preventing hypoxia-induced apoptosis in these cells. Subsequent mechanistic dissection of pathways underlying this phenomenon revealed that besides effectively inhibiting hypoxia-induced efflux of K+ ion and its downstream cell-physiological consequences; elevated extracellular KCl modulated steady state levels of cellular ATP and culminated in stabilization of AMPKα with pro-survival consequences. Also, interestingly, global gene expression profiling revealed that KCl supplementation down regulated a distinct p53-regulated cellular sub-network of genes involved in regulation of DNA replication. Additionally, we present experimental evidence for the functional role of AMPK and p53 activation during suppression of hypoxia-induced apoptosis. In conclusion, our study highlights a novel bimodal effect wherein cooperativity between restoration of K+ homeostasis and a sustainable 'metabolic quiescence' induced by AMPK activation appeared indispensible for curtailing hypoxia-induced apoptosis.
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Affiliation(s)
- Nomesh K Gopalani
- Peptide and Proteomics Division, Defence Institute of Physiology and Allied Sciences (DIPAS), DRDO, Delhi, India
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Role of Kv1.3 mitochondrial potassium channel in apoptotic signalling in lymphocytes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1251-9. [DOI: 10.1016/j.bbabio.2010.01.018] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 01/14/2010] [Accepted: 01/14/2010] [Indexed: 11/24/2022]
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Abstract
There is a great need for pharmacological approaches to enhance neural progenitor cell (NPC) function particularly in neuroinflammatory diseases with failed neuroregeneration. In diseases such as multiple sclerosis and stroke, T-cell infiltration occurs in periventricular zones where NPCs are located and is associated with irreversible neuronal loss. We studied the effect of T-cell activation on NPC functions. NPC proliferation and neuronal differentiation were impaired by granzyme B (GrB) released by the T-cells. GrB mediated its effects by the activation of a Gi-protein-coupled receptor leading to decreased intracellular levels of cAMP and subsequent expression of the voltage-dependent potassium channel, Kv1.3. Importantly, blocking channel activity with margatoxin or blocking its expression reversed the inhibitory effects of GrB on NPCs. We have thus identified a novel pathway in neurogenesis. The increased expression of Kv1.3 in pathological conditions makes it a novel target for promoting neurorestoration.
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Contribution of voltage-gated potassium channels to the regulation of apoptosis. FEBS Lett 2010; 584:2049-56. [DOI: 10.1016/j.febslet.2010.01.038] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2009] [Revised: 01/18/2010] [Accepted: 01/19/2010] [Indexed: 01/25/2023]
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Hu D, Liu J, Keblesh J, Xiong H. Involvement of the 4-aminopyridine-sensitive transient A-type K+ current in macrophage-induced neuronal injury. Eur J Neurosci 2010; 31:214-22. [PMID: 20074219 DOI: 10.1111/j.1460-9568.2009.07063.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Through their capacity to secrete, upon activation, a variety of bioactive molecules, brain macrophages (and resident microglia) play an important role in brain immune and inflammatory responses. To test our hypothesis that activated macrophages induce neuronal injury by enhancing neuronal outward K(+) current, we studied the effects of lipopolysaccharide (LPS)-stimulated human monocyte-derived macrophage (MDM) on neuronal transient A-type K(+) current (I(A)) and resultant neuronal injury in primary rat hippocampal neuronal cultures. Bath application of LPS-stimulated MDM-conditioned media (MCM+) enhanced neuronal I(A) in a concentration-dependent manner. Non-stimulated MCM (MCM-) failed to alter I(A). The enhancement of neuronal I(A) was recapitulated in neurons co-cultured with macrophages. The link of MCM(+)-induced enhancement of I(A) to MCM(+)-associated neuronal injury, as detected by propidium iodide and 4'',6-diamidino-2-phenylindol staining (DAPI) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, was demonstrated by experimental results showing that addition of I(A) blocker 4-aminopyridine to the cultures protected hippocampal neurons from MCM(+)-induced neuronal injury. Further investigation revealed that glutamate was involved in MCM(+)-induced enhancement of neuronal I(A). These results suggest that during brain inflammation macrophages (and microglia) might mediate neuronal injury via enhancement of neuronal I(A), and that neuronal K(v) channel might be a potential target for the development of therapeutic strategies for some neurodegenerative disorders by which immune and inflammatory responses are believed to be involved in the pathogenesis.
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Affiliation(s)
- Dehui Hu
- Center for Neurovirology and Neurodegenerative Disorders, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
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Rajesh RV, Kim SK, Park MR, Park MA, Jang EJ, Hong SG, Chang JS, Yoon DH, Kim TH, Lee HJ. Differential Proteome Expression of In vitro Proliferating Bovine Satellite Cells from Longissimus Dorsi, Deep Pectoral and Semitendinosus Muscle Depots in Response to Hormone Deprivation and Addition. JOURNAL OF ANIMAL SCIENCE AND TECHNOLOGY 2009. [DOI: 10.5187/jast.2009.51.6.459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Valencia-Cruz G, Shabala L, Delgado-Enciso I, Shabala S, Bonales-Alatorre E, Pottosin II, Dobrovinskaya OR. K(bg) and Kv1.3 channels mediate potassium efflux in the early phase of apoptosis in Jurkat T lymphocytes. Am J Physiol Cell Physiol 2009; 297:C1544-53. [PMID: 19794143 DOI: 10.1152/ajpcell.00064.2009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Microelectrode ion flux estimation (MIFE) and patch-clamp techniques were combined for noninvasive K(+) flux measurements and recording of activities of the dominant K(+) channels in the early phases of apoptosis in Jurkat cells. Staurosporine (STS, 1 microM) evoked rapid (peaking around 15 min) transient K(+) efflux, which then gradually decreased. This transient K(+) efflux occurred concurrently with the transient increase of the K(+) background (K(bg)) TWIK-related spinal cord K(+) channel-like current density, followed by a drastic decrease and concomitant membrane depolarization. The Kv1.3 current density remained almost constant. Kv1.3 activation was not altered by STS, whereas the inactivation was shifted to more positive potentials. Contribution of K(bg) and Kv1.3 channels to the transient and posttransient STS-induced K(+) efflux components, respectively, was confirmed by the effects of bupivacaine, predominantly blocking K(bg) current, and the Kv1.3-specific blocker margatoxin. Channel-mediated K(+) efflux provoked a substantial cellular shrinkage and affected the activation of caspases.
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Koeberle PD, Wang Y, Schlichter LC. Kv1.1 and Kv1.3 channels contribute to the degeneration of retinal ganglion cells after optic nerve transection in vivo. Cell Death Differ 2009; 4:337-46. [DOI: 10.1038/cdd.2009.113] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Zoratti M, De Marchi U, Gulbins E, Szabò I. Novel channels of the inner mitochondrial membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1787:351-63. [PMID: 19111672 DOI: 10.1016/j.bbabio.2008.11.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 11/24/2008] [Accepted: 11/26/2008] [Indexed: 12/15/2022]
Abstract
Along with a large number of carriers, exchangers and "pumps", the inner mitochondrial membrane contains ion-conducting channels which endow it with controlled permeability to small ions. Some have been shown to be the mitochondrial counterpart of channels present also in other cellular membranes. The manuscript summarizes the current state of knowledge on the major inner mitochondrial membrane channels, properties, identity and proposed functions. Considerable attention is currently being devoted to two K(+)-selective channels, mtK(ATP) and mtBK(Ca). Their activation in "preconditioning" is considered by many to underlie the protection of myocytes and other cells against subsequent ischemic damage. We have recently shown that in apoptotic lymphocytes inner membrane mtK(V)1.3 interacts with the pro-apoptotic protein Bax after the latter has inserted into the outer mitochondrial membrane. Whether the just-discovered mtIK(Ca) has similar cellular role(s) remains to be seen. The Ca(2+) "uniporter" has been characterized electrophysiologically, but still awaits a molecular identity. Chloride-selective channels are represented by the 107 pS channel, the first mitochondrial channel to be observed by patch-clamp, and by a approximately 400 pS pore we have recently been able to fully characterize in the inner membrane of mitochondria isolated from a colon tumour cell line. This we propose to represent a component of the Permeability Transition Pore. The available data exclude the previous tentative identification with porin, and indicate that it coincides instead with the still molecularly unidentified "maxi" chloride channel.
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Mitochondrial potassium channel Kv1.3 mediates Bax-induced apoptosis in lymphocytes. Proc Natl Acad Sci U S A 2008; 105:14861-6. [PMID: 18818304 DOI: 10.1073/pnas.0804236105] [Citation(s) in RCA: 165] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The potassium channel Kv1.3 has recently been located to the inner mitochondrial membrane of lymphocytes. Here, we show that mouse and human cells either genetically deficient in Kv1.3 or transfected with siRNA to suppress Kv1.3-expression resisted apoptosis induced by several stimuli, including Bax over-expression [corrected]. Retransfection of either Kv1.3 or a mitochondrial-targeted Kv1.3 restored cell death . Bax interacted with and functionally inhibited mitochondrial Kv1.3. Incubation of isolated Kv1.3-positive mitochondria with recombinant Bax, t-Bid, or toxins that bind to and inhibit Kv1.3 successively triggered hyperpolarization, formation of reactive oxygen species, release of cytochrome c, and marked depolarization. Kv1.3-deficient mitochondria were resistant to Bax, t-Bid, and the toxins. Mutation of Bax at K128, which corresponds to a conserved lysine in Kv1.3-inhibiting toxins, abrogated its effects on both Kv1.3 and mitochondria. These findings suggest that Bax mediates cytochrome c release and mitochondrial depolarization in lymphocytes, at least in part, via its interaction with mitochondrial Kv1.3.
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Potassium channels in the regulation of pulmonary artery smooth muscle cell proliferation and apoptosis: pharmacotherapeutic implications. Br J Pharmacol 2007; 153 Suppl 1:S99-S111. [PMID: 18084317 DOI: 10.1038/sj.bjp.0707635] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Maintaining the proper balance between cell apoptosis and proliferation is required for normal tissue homeostasis; when this balance is disrupted, disease such as pulmonary arterial hypertension (PAH) can result. Activity of K(+) channels plays a major role in regulating the pulmonary artery smooth muscle cell (PASMC) population in the pulmonary vasculature, as they are involved in cell apoptosis, survival and proliferation. PASMCs from PAH patients demonstrate many cellular abnormalities linked to K(+) channels, including decreased K(+) current, downregulated expression of various K(+) channels, and inhibited apoptosis. K(+) is the major intracellular cation, and the K(+) current is a major determinant of cell volume. Apoptotic volume decrease (AVD), an early hallmark and prerequisite of programmed cell death, is characterized by K(+) and Cl(-) efflux. In addition to its role in AVD, cytosolic K(+) can be inhibitory toward endogenous caspases and nucleases and can suppress mitochondrial cytochrome c release. In PASMC, K(+) channel activation accelerates AVD and enhances apoptosis, while K(+) channel inhibition decelerates AVD and inhibits apoptosis. Finally, inhibition of K(+) channels, by increasing cytosolic [Ca(2+)] as a result of membrane depolarization-mediated opening of voltage-dependent Ca(2+) channels, leads to PASMC contraction and proliferation. The goals of this review are twofold: (1) to elucidate the role of K(+) ions and K(+) channels in the proliferation and apoptosis of PASMC, with an emphasis on abnormal cell growth in human and animal models of PAH, and (2) to elaborate upon the targeting of K(+) flux pathways for pharmacological treatment of pulmonary vascular disease.
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L'Hoste S, Poet M, Duranton C, Belfodil R, Barriere HÉ, Rubera I, Tauc M, Poujeol C, Barhanin J, Poujeol P. Role of TASK2 in the Control of Apoptotic Volume Decrease in Proximal Kidney Cells. J Biol Chem 2007; 282:36692-703. [DOI: 10.1074/jbc.m703933200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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Peters J, Chin CK. Potassium loss is involved in tobacco cell death induced by palmitoleic acid and ceramide. Arch Biochem Biophys 2007; 465:180-6. [PMID: 17662229 DOI: 10.1016/j.abb.2007.05.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 05/28/2007] [Accepted: 05/30/2007] [Indexed: 12/18/2022]
Abstract
Tobacco cell death induced by palmitoleic acid (16:1), ceramide, and KCN was found to possess features associated with program cell death (PCD), including cell volume decrease, loss of membrane integrity, DNA damage, nuclear and plastid disorganization, and chromatin condensation. Cell volume decrease was found to be caused by loss of intracellular K(+). Ba(2+) was able to prevent the K(+) loss and it also protected the cells from death induced by 16:1 and ceramide but not KCN. The results suggest that K(+) loss is a critical step in plant PCD. The inability of Ba(2+) to prevent cell death was most likely due to its other effects of KCN, i.e., inhibition of cytochrome oxidase in the respiratory chain and generation of reactive oxygen species.
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Affiliation(s)
- Jeanne Peters
- Department of Plant Biology and Pathology, School of Environmental and Biological, Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
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Bortner CD, Cidlowski JA. Cell shrinkage and monovalent cation fluxes: role in apoptosis. Arch Biochem Biophys 2007; 462:176-88. [PMID: 17321483 PMCID: PMC1941616 DOI: 10.1016/j.abb.2007.01.020] [Citation(s) in RCA: 189] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Revised: 01/18/2007] [Accepted: 01/23/2007] [Indexed: 12/25/2022]
Abstract
The loss of cell volume or cell shrinkage has been a morphological hallmark of the programmed cell death process known as apoptosis. This isotonic loss of cell volume has recently been term apoptotic volume decrease or AVD to distinguish it from inherent volume regulatory responses that occurs in cells under anisotonic conditions. Recent studies examining the intracellular signaling pathways that result in this unique cellular characteristic have determined that a fundamental movement of ions, particularly monovalent ions, underlie the AVD process and plays an important role on controlling the cell death process. An efflux of intracellular potassium was shown to be a critical aspect of the AVD process, as preventing this ion loss could protect cells from apoptosis. However, potassium plays a complex role as a loss of intracellular potassium has also been shown to be beneficial to the health of the cell. Additionally, the mechanisms that a cell employs to achieve this loss of intracellular potassium vary depending on the cell type and stimulus used to induce apoptosis, suggesting multiple ways exist to accomplish the same goal of AVD. Additionally, sodium and chloride have been shown to play a vital role during cell death in both the signaling and control of AVD in various apoptotic model systems. This review examines the relationship between this morphological change and intracellular monovalent ions during apoptosis.
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Affiliation(s)
- Carl D Bortner
- The Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Department of Health and Human Services, National Institutes of Health, Research Triangle Park, NC 27709, USA.
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Wink M. Molecular modes of action of cytotoxic alkaloids: from DNA intercalation, spindle poisoning, topoisomerase inhibition to apoptosis and multiple drug resistance. THE ALKALOIDS. CHEMISTRY AND BIOLOGY 2007; 64:1-47. [PMID: 18085328 DOI: 10.1016/s1099-4831(07)64001-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Michael Wink
- Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg, 69120 Heidelberg, Germany.
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36
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Ljubkovic M, Marinovic J, Fuchs A, Bosnjak ZJ, Bienengraeber M. Targeted expression of Kir6.2 in mitochondria confers protection against hypoxic stress. J Physiol 2006; 577:17-29. [PMID: 16959852 PMCID: PMC2000685 DOI: 10.1113/jphysiol.2006.118299] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Selective K(+) transport in the inner mitochondrial membrane has been attributed to at least three different channel types: ATP-sensitive, Ca(2+)-regulated and voltage-dependent K(+) channels. Studies utilizing their selective modulators have suggested that an increased activity of these channels plays an important role in the cellular protection from metabolic stress. However, direct evidence for this effect is largely absent, and recent findings on the lack of specificity for several channel openers and blockers have questioned the actual contribution of the mitochondrial K(+) channels in the preservation of cellular viability. In order to directly investigate the role of enhanced mitochondrial K(+) uptake in cellular protection, we selectively expressed the inward rectifying K(+) channel Kir6.2 in the mitochondria of HEK293 and HL-1 cells. Targeted Kir6.2 expression was achieved by cloning the Kir6.2 gene in pCMV/mito/GFP vector and the proper trafficking to mitochondria was confirmed by colocalization studies and Western blot. An increased K(+) influx to mitochondria overexpressing Kir6.2, as evidenced by using the K(+)-sensitive PBFI AM fluorescent dye, substantially improved the cellular viability after hypoxic stress, which was assessed by lactate dehydrogenase (LDH) release. In parallel, monitoring of mitochondrial Ca(2+) during stress, via the specific indicator rhod-2, revealed a significant attenuation of Ca(2+) accumulation in mitochondria overexpressing K(+) channels. This effect was abolished in mitochondria expressing an inactive mutant of Kir6.2. Mitochondria expressing Kir6.2 K(+) channel also exhibited a significant degree of depolarization that became even more pronounced during the stress. In conclusion, this study provides the first non-pharmacological evidence that an increased K(+) influx to mitochondria protects against hypoxic stress by preventing detrimental effects of Ca(2+) overload.
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Affiliation(s)
- Marko Ljubkovic
- Department of Anesthesiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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37
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Abdalah R, Wei L, Francis K, Yu SP. Valinomycin-induced apoptosis in Chinese hamster ovary cells. Neurosci Lett 2006; 405:68-73. [PMID: 16857314 DOI: 10.1016/j.neulet.2006.06.055] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Revised: 06/16/2006] [Accepted: 06/16/2006] [Indexed: 02/02/2023]
Abstract
Accumulating evidence endorses that excessive K(+) efflux is an ionic mechanism underlying apoptosis both in neuronal and non-neuronal cells. K(+) channels play important roles in mediating the pro-apoptotic K(+) efflux. Chinese hamster ovary (CHO) cells have been widely used for gene transfection experiments. These cells lack detectable endogenous voltage-gated K(+) channels. We were interested in knowing whether the absence of endogenous K(+) channels would render wild-type CHO cells more resistant to apoptotic death. We also wished to determine if direct stimulation of K(+) efflux would trigger apoptosis in these cells. Exposing CHO cells to hypoxia (1% O(2)) or to a typical apoptotic insult of serum deprivation for up to 24h did not affect cell survival. On the other hand, the K(+) ionophore valinomycin caused substantial cell death within 12h of its application. Valinomycin-treated CHO cells underwent several apoptotic events, including phosphatidylserine (PS) membrane translocation, caspase-3 activation, and mitochondrial membrane depolarization during the first few hours of exposure. Reducing K(+) efflux by elevating extracellular K(+) concentrations noticeably attenuated valinomycin-induced cell death. This study reinforces a K(+) efflux-mediated apoptotic mechanism in CHO cells and may help to explain the unique feature of their higher tolerance to apoptosis.
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Affiliation(s)
- Rany Abdalah
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC 29425, United States
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38
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Abstract
A proper rate of programmed cell death or apoptosis is required to maintain normal tissue homeostasis. In disease states such as cancer and some forms of hypertension, apoptosis is blocked, resulting in hyperplasia. In neurodegenerative diseases, uncontrolled apoptosis leads to loss of brain tissue. The flow of ions in and out of the cell and its intracellular organelles is becoming increasingly linked to the generation of many of these diseased states. This review focuses on the transport of K(+) across the cell membrane and that of the mitochondria via integral K(+)-permeable channels. We describe the different types of K(+) channels that have been identified, and investigate the roles they play in controlling the different phases of apoptosis: early cell shrinkage, cytochrome c release, caspase activation, and DNA fragmentation. Attention is also given to K(+) channels on the inner mitochondrial membrane, whose activity may underlie anti- or pro-apoptotic mechanisms in neurons and cardiomyocytes.
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Affiliation(s)
- E D Burg
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, MC 0725, La Jolla, 92093-0725, USA
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39
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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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40
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Abstract
Continuous generation of ATP by mitochondrial oxidative phosphorylation is essential to maintain function in mechanically active cells such as cardiomyocytes. Emerging evidence indicates that mitochondrial ion channels activated by reactive oxygen species can induce a mitochondrial "critical" state, which can scale to cause electrical and contractile dysfunction of the cardiac cell and, ultimately, the whole heart. Here we focus on how mitochondrial ion channels participate in life-and-death decisions of the cell and discuss the challenges ahead for translating recent findings into novel therapeutic applications.
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Affiliation(s)
- Brian O'Rourke
- Institute of Molecular Cardiobiology, Division of Cardiology, The Johns Hopkins University, Baltimore, Maryland, USA.
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41
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Bollinger CR, Teichgräber V, Gulbins E. Ceramide-enriched membrane domains. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1746:284-94. [PMID: 16226325 DOI: 10.1016/j.bbamcr.2005.09.001] [Citation(s) in RCA: 256] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Revised: 09/05/2005] [Accepted: 09/06/2005] [Indexed: 01/05/2023]
Abstract
Cellular activation involves the re-organization of receptor molecules and the intracellular signalosom in the cell membrane. Recent studies indicate that specialized domains of the cell membrane, termed rafts, are central for the spatial organization of receptors and signaling molecules. Rafts are converted into larger membrane platforms by activity of the acid sphingomyelinase, which hydrolyses raft-sphingomyelin to ceramide. Ceramide molecules spontaneously associate to form ceramide-enriched microdomains, which fuse to large ceramide-enriched membrane platforms. The acid sphingomyelinase is activated by multiple stimuli including CD95, CD40, DR5/TRAIL, CD20, FcgammaRII, CD5, LFA-1, CD28, TNF, the Interleukin-1 receptor, the PAF-receptor, CD14, infection with P. aeruginosa, S. aureus, N. gonorrhoeae, Sindbis-Virus, Rhinovirus, treatment with gamma-irradiation, UV-light, doxorubicin, cisplatin, disruption of integrin-signaling and under some conditions of developmental death. Ceramide-enriched membrane platforms serve the clustering of receptors, the recruitment of intracellular signaling molecules and the exclusion of inhibitory signaling factors and, thus, facilitate signal transduction initiated by the specific stimulus.
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Affiliation(s)
- Claudia R Bollinger
- Department of Molecular Biology, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
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42
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Szabò I, Bock J, Jekle A, Soddemann M, Adams C, Lang F, Zoratti M, Gulbins E. A novel potassium channel in lymphocyte mitochondria. J Biol Chem 2005; 280:12790-8. [PMID: 15632141 DOI: 10.1074/jbc.m413548200] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The margatoxin-sensitive Kv1.3 is the major potassium channel in the plasma membrane of T lymphocytes. Electron microscopy, patch clamp, and immunological studies identified the potassium channel Kv1.3, thought to be localized exclusively in the cell membrane, in the inner mitochondrial membrane of T lymphocytes. Patch clamp of mitoplasts and mitochondrial membrane potential measurements disclose the functional expression of a mitochondrial margatoxin-sensitive potassium channel. To identify unambiguously the mitochondrial localization of Kv1.3, we employed a genetic model and stably transfected CTLL-2 cells, which are genetically deficient for this channel, with Kv1.3. Mitochondria isolated from Kv1.3-reconstituted CTLL-2 expressed the channel protein and displayed an activity, which was identical to that observed in Jurkat mitochondria, whereas mitochondria of mock-transfected cells lacked a channel with the characteristics of Kv1.3. Our data provide the first molecular identification of a mitochondrial potassium conductance.
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Affiliation(s)
- Ildikò Szabò
- Department of Biology, University of Padova, 35121 Padova, Italy.
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43
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Tipparaju SM, Saxena N, Liu SQ, Kumar R, Bhatnagar A. Differential regulation of voltage-gated K+ channels by oxidized and reduced pyridine nucleotide coenzymes. Am J Physiol Cell Physiol 2004; 288:C366-76. [PMID: 15469953 DOI: 10.1152/ajpcell.00354.2004] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The activity of the voltage-sensitive K+ (Kv) channels varies as a function of the intracellular redox state and metabolism, and several Kv channels act as oxygen sensors. However, the mechanisms underlying the metabolic and redox regulation of these channels remain unclear. In this study we investigated the regulation of Kv channels by pyridine nucleotides. Heterologous expression of Kvalpha1.5 in COS-7 cells led to the appearance of noninactivating currents. Inclusion of 0.1-1 mM NAD+ or 0.03-0.5 mM NADP+ in the internal solution of the patch pipette did not affect Kv currents. However, 0.5 and 1 mM NAD+ and 0.1 and 0.5 mM NADP+ prevented inactivation of Kv currents in cells transfected with Kvalpha1.5 and Kvbeta1.3 and shifted the voltage dependence of activation to depolarized potentials. The Kvbeta-dependent inactivation of Kvalpha currents was also decreased by internal pipette perfusion of the cell with 1 mM NAD+. The Kvalpha1.5-Kvbeta1.3 currents were unaffected by the internal application of 0.1 mM NADPH or 0.1 or 1 mM NADH. Excised inside-out patches from cells expressing Kvalpha1.5-Kvbeta1.3 showed transient single-channel activity. The mean open time and the open probability of these currents were increased by the inclusion of 1 mM NAD+ in the perfusate. These results suggest that NAD(P)+ prevents Kvbeta-mediated inactivation of Kv currents and provide a novel mechanism by which pyridine nucleotides could regulate specific K+ currents as a function of the cellular redox state [NAD(P)H-to-NAD(P)+ ratio].
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Affiliation(s)
- Srinivas M Tipparaju
- Division of Cardiology, Department of Medicine, University of Louisville, Louisville, Kentucky 40202, USA
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44
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Enomoto R, Komai T, Yoshida Y, Sugahara C, Kawaguchi E, Okazaki K, Kinoshita H, Komatsu H, Konishi Y, Lee E. Terfenadine induces thymocyte apoptosis via mitochondrial pathway. Eur J Pharmacol 2004; 496:11-21. [PMID: 15288570 DOI: 10.1016/j.ejphar.2004.05.048] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Accepted: 05/06/2004] [Indexed: 10/26/2022]
Abstract
The treatment of rat thymocytes with 10 microM terfenadine resulted in a significant increase in DNA fragmentation. The DNA fragmentation induced by terfenadine was dependent on its concentration and incubation time. In terfenadine-treated cells, the translocation of phosphatidylserine from the inside of plasma membrane to the outside, an early event of the apoptotic process, and chromatin condensation, the morphological characterization of apoptotic cell death, were observed. Terfenadine stimulated caspase-8, -9 and -3-like activities in an incubation time-dependent manner in thymocytes. The active forms of caspase-3 and -9 were detected in the extract from terfenadine-treated cells by immunoblotting analysis using specific antibodies to caspases, but active caspase-8 was not found in this fraction. Decrease in mitochondrial membrane potential and the release of cytochrome c from mitochondria to cytosol were observed in terfenadine-treated thymocytes. These results suggest that terfenadine induces apoptosis in rat thymocytes via mitochondrial pathway.
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Affiliation(s)
- Riyo Enomoto
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Japan
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45
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Brevnova EE, Platoshyn O, Zhang S, Yuan JXJ. Overexpression of human KCNA5 increases IK V and enhances apoptosis. Am J Physiol Cell Physiol 2004; 287:C715-22. [PMID: 15140747 DOI: 10.1152/ajpcell.00050.2004] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Apoptotic cell shrinkage, an early hallmark of apoptosis, is regulated by K+ efflux and K+ channel activity. Inhibited apoptosis and downregulated K+ channels in pulmonary artery smooth muscle cells (PASMC) have been implicated in development of pulmonary vascular medial hypertrophy and pulmonary hypertension. The objective of this study was to test the hypothesis that overexpression of KCNA5, which encodes a delayed-rectifier voltage-gated K+ (Kv) channel, increases K+ currents and enhances apoptosis. Transient transfection of KCNA5 caused 25- to 34-fold increase in KCNA5 channel protein level and 24- to 29-fold increase in Kv channel current (I(K(V))) at +60 mV in COS-7 and rat PASMC, respectively. In KCNA5-transfected COS-7 cells, staurosporine (ST)-mediated increases in caspase-3 activity and the percentage of cells undergoing apoptosis were both enhanced, whereas basal apoptosis (without ST stimulation) was unchanged compared with cells transfected with an empty vector. In rat PASMC, however, transfection of KCNA5 alone caused marked increase in basal apoptosis, in addition to enhancing ST-mediated apoptosis. Furthermore, ST-induced apoptotic cell shrinkage was significantly accelerated in COS-7 cells and rat PASMC transfected with KCNA5, and blockade of KCNA5 channels with 4-aminopyridine (4-AP) reduced K+ currents through KCNA5 channels and inhibited ST-induced apoptosis in KCNA5-transfected COS-7 cells. Overexpression of the human KCNA5 gene increases K+ currents (i.e., K+ efflux or loss), accelerates apoptotic volume decrease (AVD), increases caspase-3 activity, and induces apoptosis. Induction of apoptosis in PASMC by KCNA5 gene transfer may serve as an important strategy for preventing the progression of pulmonary vascular wall thickening and for treating patients with idiopathic pulmonary arterial hypertension (IPAH).
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MESH Headings
- 4-Aminopyridine/pharmacology
- Animals
- Apoptosis/drug effects
- Apoptosis/physiology
- Blotting, Western
- COS Cells
- Caspase 3
- Caspases/drug effects
- Caspases/metabolism
- Cells, Cultured
- Chlorocebus aethiops
- Electrophysiology
- Enzyme Activation/drug effects
- Enzyme Activation/physiology
- Enzyme Inhibitors/pharmacology
- Humans
- Hypertension, Pulmonary/physiopathology
- Image Processing, Computer-Assisted
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/physiology
- Patch-Clamp Techniques
- Potassium Channel Blockers/pharmacology
- Potassium Channels, Voltage-Gated/drug effects
- Potassium Channels, Voltage-Gated/physiology
- Rats
- Staurosporine/pharmacology
- Transfection
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Affiliation(s)
- Elena E Brevnova
- Division of Pulmonary and Critical Care Medicine, Dept. of Medicine, Medical Teaching Facility, University of California-San Diego, #0725, 9500 Gilman Drive, La Jolla, CA 92093-0725, USA
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46
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Okada Y, Maeno E, Shimizu T, Manabe K, Mori SI, Nabekura T. Dual roles of plasmalemmal chloride channels in induction of cell death. Pflugers Arch 2004; 448:287-95. [PMID: 15103464 DOI: 10.1007/s00424-004-1276-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Accepted: 03/04/2004] [Indexed: 10/26/2022]
Abstract
Even under anisotonic conditions, most cells can regulate their volume by mechanisms called regulatory volume decrease (RVD) and increase (RVI) after osmotic swelling or shrinkage, respectively. In contrast, the initial processes of necrosis and apoptosis are associated with persistent swelling and shrinkage. Necrotic volume increase (NVI) is initiated by uptake of osmolytes, such as Na+, Cl- and lactate, under conditions of injury, hypoxia, ischaemia, acidosis or lactacidosis. Persistence of NVI is caused by dysfunction of RVD due to impairment of volume-sensitive Cl- channels under conditions of ATP deficiency or lactacidosis. Both lactacidosis-induced RVD dysfunction and necrotic cell death are prevented by pretreatment of cells with the vacuolating cytotoxin-A (VacA) toxin protein purified from Helicobacter pylori, which forms a lactacidosis-resistant anion channel. Apoptotic volume decrease (AVD) is triggered by activation of K+ and Cl- conductances following stimulation with a mitochondrion-mediated or death receptor-mediated apoptosis inducer. Apoptotic cell death can be prevented by blocking the Cl- channels but not the K+-Cl- cotransporters. Thus, the volume regulatory anion channel plays, unless impaired, a cell-rescuing role in the necrotic process by ensuring RVD after swelling induced by necrotic insults, whereas normotonic activation of the anion channel plays a cell-killing role in the apoptotic process by triggering AVD following stimulation with apoptosis inducers.
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Affiliation(s)
- Yasunobu Okada
- Department of Cell Physiology, National Institute for Physiological Sciences, 444-8585 Okazaki, Japan.
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47
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Szabò I, Adams C, Gulbins E. Ion channels and membrane rafts in apoptosis. Pflugers Arch 2004; 448:304-12. [PMID: 15071744 DOI: 10.1007/s00424-004-1259-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2004] [Accepted: 02/19/2004] [Indexed: 10/26/2022]
Abstract
Ion channels have been demonstrated to be a central element in the induction and the execution of apoptosis. In particular, mitochondrial ion channels, including not only the permeability transition pore but also a mitochondrial, ATP-sensitive (mKATP) channel as well as a mitochondrial calcium-activated potassium channel are involved critically in apoptotic changes in mitochondria. Ion channels in the cell membrane that are altered by induction of apoptosis include potassium, chloride and calcium channels. The Kv1.3 potassium channel belongs to the best-characterized ion channels involved in apoptosis and a genetic model of cells deficient for Kv1.3 has indicated a critical role for Kv1.3, at least in some forms of apoptosis. The mechanisms regulating ion channels during apoptosis are, however, still poorly defined. Recent studies have suggested a function for distinct membrane domains, termed rafts, in the cell membrane for the regulation of ion channels during apoptosis. Small sphingolipid- and cholesterol-enriched membrane domains are modified by many apoptotic stimuli to form large ceramide-enriched membrane platforms. These platforms serve to cluster receptor molecules, to re-organize intracellular signalling molecules including ion channels, to bring ion channels into close contact with their regulators and/or to separate proteins from a specific ion channel. Finally, the lipid composition of the cell membrane might be involved directly in ion channel regulation.
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Affiliation(s)
- I Szabò
- Department of Biology, University of Padua, Via Colombo 6, 35121 Padua, Italy
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48
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Remillard CV, Yuan JXJ. Activation of K+ channels: an essential pathway in programmed cell death. Am J Physiol Lung Cell Mol Physiol 2004; 286:L49-67. [PMID: 14656699 DOI: 10.1152/ajplung.00041.2003] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cell apoptosis and proliferation are two counterparts in sharing the responsibility for maintaining normal tissue homeostasis. In recent years, the process of the programmed cell death has gained much interest because of its influence on malignant cell growth and other pathological states. Apoptosis is characterized by a distinct series of morphological and biochemical changes that result in cell shrinkage, DNA breakdown, and, ultimately, phagocytic death. Diverse external and internal stimuli trigger apoptosis, and enhanced K+ efflux has been shown to be an essential mediator of not only early apoptotic cell shrinkage, but also of downstream caspase activation and DNA fragmentation. The goal of this review is to discuss the role(s) played by K+ transport or flux across the plasma membrane in the regulation of the apoptotic volume decrease and apoptosis. Attention has also been paid to the role of inner mitochondrial membrane ion transport in the regulation of mitochondrial permeability and apoptosis. We provide specific examples of how deregulation of the apoptotic process contributes to pulmonary arterial medial hypertrophy, a major pathological feature in patients with pulmonary arterial hypertension. Finally, we discuss the targeting of K+ channels as a potential therapeutic tool in modulating apoptosis to maintain the balance between cell proliferation and cell death that is essential to the normal development and function of an organism.
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Affiliation(s)
- Carmelle V Remillard
- Division of Pulmonary and Critical Care Medicine, Dep[artment of Medicine, School of Medicine, University of California, San Diego, 92103-8382, USA
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49
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Vicente R, Escalada A, Coma M, Fuster G, Sánchez-Tilló E, López-Iglesias C, Soler C, Solsona C, Celada A, Felipe A. Differential voltage-dependent K+ channel responses during proliferation and activation in macrophages. J Biol Chem 2003; 278:46307-20. [PMID: 12923194 DOI: 10.1074/jbc.m304388200] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Voltage-dependent K+ channels (VDPC) are expressed in most mammalian cells and involved in the proliferation and activation of lymphocytes. However, the role of VDPC in macrophage responses is not well established. This study was undertaken to characterize VDPC in macrophages and determine their physiological role during proliferation and activation. Macrophages proliferate until an endotoxic shock halts cell growth and they become activated. By inducing a schedule that is similar to the physiological pattern, we have identified the VDPC in non-transformed bone marrow-derived macrophages and studied their regulation. Patch clamp studies demonstrated that cells expressed outward delayed and inwardly rectifying K+ currents. Pharmacological data, mRNA, and protein analysis suggest that these currents were mainly mediated by Kv1.3 and Kir2.1 channels. Macrophage colony-stimulating factor-dependent proliferation induced both channels. Lipopolysaccharide (LPS)-induced activation differentially regulated VDPC expression. While Kv1.3 was further induced, Kir2.1 was down-regulated. TNF-alpha mimicked LPS effects, and studies with TNF-alpha receptor I/II double knockout mice demonstrated that LPS regulation mediates such expression by TNF-alpha-dependent and -independent mechanisms. This modulation was dependent on mRNA and protein synthesis. In addition, bone marrow-derived macrophages expressed Kv1.5 mRNA with no apparent regulation. VDPC activities seem to play a critical role during proliferation and activation because not only cell growth, but also inducible nitric-oxide synthase expression were inhibited by blocking their activities. Taken together, our results demonstrate that the differential regulation of VDPC is crucial in intracellular signals determining the specific macrophage response.
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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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50
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Storey NM, Gómez-Angelats M, Bortner CD, Armstrong DL, Cidlowski JA. Stimulation of Kv1.3 potassium channels by death receptors during apoptosis in Jurkat T lymphocytes. J Biol Chem 2003; 278:33319-26. [PMID: 12807917 DOI: 10.1074/jbc.m300443200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The loss of intracellular potassium is a pivotal step in the induction of apoptosis but the mechanisms underlying this response are poorly understood. Here we report caspase-dependent stimulation of potassium channels by the Fas receptor in a human Jurkat T cell line. Receptor activation with Fas ligand for 30 min increased the amplitude of voltage-activated potassium currents 2-fold on average. This produces a sustained outward current, approximately 10 pA, at physiological membrane potentials during Fas ligand-induced apoptosis. Both basal and Fas ligand-induced currents were blocked completely by toxins that selectively inhibit Kv1.3 potassium channels. Kv1.3 stimulation required the expression of Fas-associated death domain protein and activation of caspase 8, but did not require activation of caspase 3 or protein synthesis. Furthermore, Kv1.3 stimulation by Fas ligand was prevented by chronic stimulation of protein kinase C with 20 nm phorbol 12-myristate 13-acetate during Fas ligand treatment, which also blocks apoptosis. Thus, Fas ligand increases Kv1.3 channel activity through the same canonical apoptotic signaling cascade that is required for potassium efflux, cell shrinkage, and apoptosis.
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Affiliation(s)
- Nina M Storey
- Membrane Signaling Group, Laboratory of Signal Transduction, Department of Health and Human Services, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA
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