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Maliszewska-Olejniczak K, Pytlak K, Dabrowska A, Zochowska M, Hoser J, Lukasiak A, Zajac M, Kulawiak B, Bednarczyk P. Deficiency of the BK Ca potassium channel displayed significant implications for the physiology of the human bronchial epithelium. Mitochondrion 2024; 76:101880. [PMID: 38604459 DOI: 10.1016/j.mito.2024.101880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/14/2024] [Accepted: 04/07/2024] [Indexed: 04/13/2024]
Abstract
Plasma membrane large-conductance calcium-activated potassium (BKCa) channels are important players in various physiological processes, including those mediated by epithelia. Like other cell types, human bronchial epithelial (HBE) cells also express BKCa in the inner mitochondrial membrane (mitoBKCa). The genetic relationships between these mitochondrial and plasma membrane channels and the precise role of mitoBKCa in epithelium physiology are still unclear. Here, we tested the hypothesis that the mitoBKCa channel is encoded by the same gene as the plasma membrane BKCa channel in HBE cells. We also examined the impact of channel loss on the basic function of HBE cells, which is to create a tight barrier. For this purpose, we used CRISPR/Cas9 technology in 16HBE14o- cells to disrupt the KCNMA1 gene, which encodes the α-subunit responsible for forming the pore of the plasma membrane BKCa channel. Electrophysiological experiments demonstrated that the disruption of the KCNMA1 gene resulted in the loss of BKCa-type channels in the plasma membrane and mitochondria. We have also shown that HBE ΔαBKCa cells exhibited a significant decrease in transepithelial electrical resistance which indicates a loss of tightness of the barrier created by these cells. We have also observed a decrease in mitochondrial respiration, which indicates a significant impairment of these organelles. In conclusion, our findings indicate that a single gene encodes both populations of the channel in HBE cells. Furthermore, this channel is critical for maintaining the proper function of epithelial cells as a cellular barrier.
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Affiliation(s)
- Kamila Maliszewska-Olejniczak
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland
| | - Karolina Pytlak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Adrianna Dabrowska
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland
| | - Monika Zochowska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Jakub Hoser
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland
| | - Agnieszka Lukasiak
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland
| | - Miroslaw Zajac
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland.
| | - Piotr Bednarczyk
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland.
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2
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Głuchowska A, Kalenik B, Kulawiak B, Wrzosek A, Szewczyk A, Bednarczyk P, Mosieniak G. Lack of activity of the mitochondrial large-conductance calcium-regulated potassium channels in senescent vascular smooth muscle cells. Mech Ageing Dev 2023; 215:111871. [PMID: 37689317 DOI: 10.1016/j.mad.2023.111871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 09/01/2023] [Accepted: 09/06/2023] [Indexed: 09/11/2023]
Abstract
A limited number of studies have shown functional changes in mitochondrial ion channels in aging and senescent cells. We have identified, for the first time, mitochondrial large-conductance calcium-regulated potassium channels in human smooth muscle mitochondria. This channel, with a conductance of 273 pS, was regulated by calcium ions and membrane potential. Additionally, it was activated by the potassium channel opener NS11021 and blocked by paxilline. Importantly, we have shown that senescence of these cells induced by hydrogen peroxide treatment leads to the disappearance of potassium channel protein levels and channel activity measured by the single channel patch-clamp technique. Our data suggest that disturbances in the expression of mitochondrial large conductance calcium-regulated potassium channels may be hallmarks of cellular senescence and contribute to the misregulation of mitochondrial function in senescent cells.
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Affiliation(s)
- Agata Głuchowska
- Laboratory of Molecular Bases of Aging, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland
| | - Barbara Kalenik
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland
| | - Antoni Wrzosek
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland
| | - Piotr Bednarczyk
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland.
| | - Grażyna Mosieniak
- Laboratory of Molecular Bases of Aging, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland.
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3
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Kulawiak B, Żochowska M, Bednarczyk P, Galuba A, Stroud DA, Szewczyk A. Loss of the large conductance calcium-activated potassium channel causes an increase in mitochondrial reactive oxygen species in glioblastoma cells. Pflugers Arch 2023; 475:1045-1060. [PMID: 37401985 PMCID: PMC10409681 DOI: 10.1007/s00424-023-02833-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/12/2023] [Accepted: 06/20/2023] [Indexed: 07/05/2023]
Abstract
Mitochondrial potassium (mitoK) channels play an important role in cellular physiology. These channels are expressed in healthy tissues and cancer cells. Activation of mitoK channels can protect neurons and cardiac tissue against injury induced by ischemia-reperfusion. In cancer cells, inhibition of mitoK channels leads to an increase in mitochondrial reactive oxygen species, which leads to cell death. In glioma cell activity of the mitochondrial, large conductance calcium-activated potassium (mitoBKCa) channel is regulated by the mitochondrial respiratory chain. In our project, we used CRISPR/Cas9 technology in human glioblastoma U-87 MG cells to generate knockout cell lines lacking the α-subunit of the BKCa channel encoded by the KCNMA1 gene, which also encodes cardiac mitoBKCa. Mitochondrial patch-clamp experiments showed the absence of an active mitoBKCa channel in knockout cells. Additionally, the absence of this channel resulted in increased levels of mitochondrial reactive oxygen species. However, analysis of the mitochondrial respiration rate did not show significant changes in oxygen consumption in the cell lines lacking BKCa channels compared to the wild-type U-87 MG cell line. These observations were reflected in the expression levels of selected mitochondrial genes, organization of the respiratory chain, and mitochondrial morphology, which did not show significant differences between the analyzed cell lines. In conclusion, we show that in U-87 MG cells, the pore-forming subunit of the mitoBKCa channel is encoded by the KCNMA1 gene. Additionally, the presence of this channel is important for the regulation of reactive oxygen species levels in mitochondria.
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Affiliation(s)
- Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St, 02-093, Warsaw, Poland.
| | - Monika Żochowska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St, 02-093, Warsaw, Poland
| | - Piotr Bednarczyk
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences-SGGW, Warsaw, Poland
| | - Andrzej Galuba
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St, 02-093, Warsaw, Poland
| | - David A Stroud
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, Australia
- Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC, Australia
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St, 02-093, Warsaw, Poland
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Krajewska M, Szewczyk A, Kulawiak B, Koprowski P. Pharmacological Characterization of a Recombinant Mitochondrial ROMK2 Potassium Channel Expressed in Bacteria and Reconstituted in Planar Lipid Bilayers. Membranes (Basel) 2023; 13:360. [PMID: 36984747 PMCID: PMC10052516 DOI: 10.3390/membranes13030360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/10/2023] [Accepted: 03/16/2023] [Indexed: 06/18/2023]
Abstract
In the inner mitochondrial membrane, several potassium channels that play a role in cell life and death have been identified. One of these channels is the ATP-regulated potassium channel (mitoKATP). The ROMK2 potassium channel is a potential molecular component of the mitoKATP channel. The current study aimed to investigate the pharmacological modulation of the activity of the ROMK2 potassium channel expressed in Escherichia coli bacteria. ROMK2 was solubilized in polymer nanodiscs and incorporated in planar lipid bilayers. The impact of known mitoKATP channel modulators on the activity of the ROMK2 was characterized. We found that the ROMK2 channel was activated by the mitoKATP channel opener diazoxide and blocked by mitoKATP inhibitors such as ATP/Mg2+, 5-hydroxydecanoic acid, and antidiabetic sulfonylurea glibenclamide. These results indicate that the ROMK2 potassium protein may be a pore-forming subunit of mitoKATP and that the impact of channel modulators is not related to the presence of accessory proteins.
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Affiliation(s)
- Milena Krajewska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, 02-093 Warsaw, Poland
- Interdisciplinary Laboratory of Molecular Biology and Biophysics, Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, 02-093 Warsaw, Poland
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, 02-093 Warsaw, Poland
| | - Piotr Koprowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, 02-093 Warsaw, Poland
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5
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Schulte U, den Brave F, Haupt A, Gupta A, Song J, Müller CS, Engelke J, Mishra S, Mårtensson C, Ellenrieder L, Priesnitz C, Straub SP, Doan KN, Kulawiak B, Bildl W, Rampelt H, Wiedemann N, Pfanner N, Fakler B, Becker T. Mitochondrial complexome reveals quality-control pathways of protein import. Nature 2023; 614:153-159. [PMID: 36697829 PMCID: PMC9892010 DOI: 10.1038/s41586-022-05641-w] [Citation(s) in RCA: 34] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 12/09/2022] [Indexed: 01/26/2023]
Abstract
Mitochondria have crucial roles in cellular energetics, metabolism, signalling and quality control1-4. They contain around 1,000 different proteins that often assemble into complexes and supercomplexes such as respiratory complexes and preprotein translocases1,3-7. The composition of the mitochondrial proteome has been characterized1,3,5,6; however, the organization of mitochondrial proteins into stable and dynamic assemblies is poorly understood for major parts of the proteome1,4,7. Here we report quantitative mapping of mitochondrial protein assemblies using high-resolution complexome profiling of more than 90% of the yeast mitochondrial proteome, termed MitCOM. An analysis of the MitCOM dataset resolves >5,200 protein peaks with an average of six peaks per protein and demonstrates a notable complexity of mitochondrial protein assemblies with distinct appearance for respiration, metabolism, biogenesis, dynamics, regulation and redox processes. We detect interactors of the mitochondrial receptor for cytosolic ribosomes, of prohibitin scaffolds and of respiratory complexes. The identification of quality-control factors operating at the mitochondrial protein entry gate reveals pathways for preprotein ubiquitylation, deubiquitylation and degradation. Interactions between the peptidyl-tRNA hydrolase Pth2 and the entry gate led to the elucidation of a constitutive pathway for the removal of preproteins. The MitCOM dataset-which is accessible through an interactive profile viewer-is a comprehensive resource for the identification, organization and interaction of mitochondrial machineries and pathways.
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Affiliation(s)
- Uwe Schulte
- grid.5963.9Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany ,grid.5963.9CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Fabian den Brave
- grid.10388.320000 0001 2240 3300Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Alexander Haupt
- grid.5963.9Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Arushi Gupta
- grid.10388.320000 0001 2240 3300Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany ,grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jiyao Song
- grid.10388.320000 0001 2240 3300Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany ,grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Catrin S. Müller
- grid.5963.9Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jeannine Engelke
- grid.10388.320000 0001 2240 3300Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Swadha Mishra
- grid.10388.320000 0001 2240 3300Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Christoph Mårtensson
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany ,Present Address: MTIP, Basel, Switzerland
| | - Lars Ellenrieder
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany ,grid.419481.10000 0001 1515 9979Present Address: Novartis, Basel, Switzerland
| | - Chantal Priesnitz
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sebastian P. Straub
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany ,grid.5963.9Faculty of Biology, University of Freiburg, Freiburg, Germany ,grid.482402.8Present Address: Sanofi-Aventis (Suisse), Vernier, Switzerland
| | - Kim Nguyen Doan
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Bogusz Kulawiak
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany ,grid.413454.30000 0001 1958 0162Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Wolfgang Bildl
- grid.5963.9Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Heike Rampelt
- grid.5963.9CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany ,grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Nils Wiedemann
- grid.5963.9CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany ,grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany ,grid.5963.9BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Nikolaus Pfanner
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany. .,Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany. .,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany.
| | - Bernd Fakler
- Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany. .,CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany. .,Center for Basics in NeuroModulation, Freiburg, Germany.
| | - Thomas Becker
- grid.10388.320000 0001 2240 3300Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
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Abstract
In this paper, the current challenges of mitochondrial potassium channels research were critically reviewed. Even though recent progress in understanding K+ traffic in mitochondria has been substantial, some basic issues of this process remain unresolved. Here, we focused on the critical discussion of the molecular identity of various mitochondrial potassium channels. This point helps to clarify why there are different potassium channels in specific mitochondria. We also described interactions of mitochondrial potassium channel subunits with other mitochondrial proteins. Posttranslational modifications of mitochondrial potassium channels and their import are essential but unexplored research areas. Additionally, problems with the pharmacological targeting of mitochondrial potassium channel were illustrated. Finally, the limitation of the techniques used to measure mitochondrial potassium channels was explained. We believe that recognizing these problems may be interesting for readers but will also help to progress the field of mitochondrial potassium channels.
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Affiliation(s)
- Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
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7
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Wrzosek A, Gałecka S, Żochowska M, Olszewska A, Kulawiak B. Alternative Targets for Modulators of Mitochondrial Potassium Channels. Molecules 2022; 27:299. [PMID: 35011530 PMCID: PMC8746388 DOI: 10.3390/molecules27010299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 12/17/2022] Open
Abstract
Mitochondrial potassium channels control potassium influx into the mitochondrial matrix and thus regulate mitochondrial membrane potential, volume, respiration, and synthesis of reactive oxygen species (ROS). It has been found that pharmacological activation of mitochondrial potassium channels during ischemia/reperfusion (I/R) injury activates cytoprotective mechanisms resulting in increased cell survival. In cancer cells, the inhibition of these channels leads to increased cell death. Therefore, mitochondrial potassium channels are intriguing targets for the development of new pharmacological strategies. In most cases, however, the substances that modulate the mitochondrial potassium channels have a few alternative targets in the cell. This may result in unexpected or unwanted effects induced by these compounds. In our review, we briefly present the various classes of mitochondrial potassium (mitoK) channels and describe the chemical compounds that modulate their activity. We also describe examples of the multidirectional activity of the activators and inhibitors of mitochondrial potassium channels.
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Affiliation(s)
- Antoni Wrzosek
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.W.); (S.G.); (M.Ż.)
| | - Shur Gałecka
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.W.); (S.G.); (M.Ż.)
| | - Monika Żochowska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.W.); (S.G.); (M.Ż.)
| | - Anna Olszewska
- Department of Histology, Medical University of Gdansk, 1a Debinki, 80-211 Gdansk, Poland;
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.W.); (S.G.); (M.Ż.)
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8
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Kulawiak B, Bednarczyk P, Szewczyk A. Multidimensional Regulation of Cardiac Mitochondrial Potassium Channels. Cells 2021; 10:1554. [PMID: 34205420 PMCID: PMC8235349 DOI: 10.3390/cells10061554] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/11/2021] [Accepted: 06/15/2021] [Indexed: 02/07/2023] Open
Abstract
Mitochondria play a fundamental role in the energetics of cardiac cells. Moreover, mitochondria are involved in cardiac ischemia/reperfusion injury by opening the mitochondrial permeability transition pore which is the major cause of cell death. The preservation of mitochondrial function is an essential component of the cardioprotective mechanism. The involvement of mitochondrial K+ transport in this complex phenomenon seems to be well established. Several mitochondrial K+ channels in the inner mitochondrial membrane, such as ATP-sensitive, voltage-regulated, calcium-activated and Na+-activated channels, have been discovered. This obliges us to ask the following question: why is the simple potassium ion influx process carried out by several different mitochondrial potassium channels? In this review, we summarize the current knowledge of both the properties of mitochondrial potassium channels in cardiac mitochondria and the current understanding of their multidimensional functional role. We also critically summarize the pharmacological modulation of these proteins within the context of cardiac ischemia/reperfusion injury and cardioprotection.
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Affiliation(s)
- Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland;
| | - Piotr Bednarczyk
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland;
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland;
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9
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Sek A, Kampa RP, Kulawiak B, Szewczyk A, Bednarczyk P. Identification of the Large-Conductance Ca 2+-Regulated Potassium Channel in Mitochondria of Human Bronchial Epithelial Cells. Molecules 2021; 26:molecules26113233. [PMID: 34072205 PMCID: PMC8199365 DOI: 10.3390/molecules26113233] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/19/2021] [Accepted: 05/24/2021] [Indexed: 12/18/2022] Open
Abstract
Mitochondria play a key role in energy metabolism within the cell. Potassium channels such as ATP-sensitive, voltage-gated or large-conductance Ca2+-regulated channels have been described in the inner mitochondrial membrane. Several hypotheses have been proposed to describe the important roles of mitochondrial potassium channels in cell survival and death pathways. In the current study, we identified two populations of mitochondrial large-conductance Ca2+-regulated potassium (mitoBKCa) channels in human bronchial epithelial (HBE) cells. The biophysical properties of the channels were characterized using the patch-clamp technique. We observed the activity of the channel with a mean conductance close to 285 pS in symmetric 150/150 mM KCl solution. Channel activity was increased upon application of the potassium channel opener NS11021 in the micromolar concentration range. The channel activity was completely inhibited by 1 µM paxilline and 300 nM iberiotoxin, selective inhibitors of the BKCa channels. Based on calcium and iberiotoxin modulation, we suggest that the C-terminus of the protein is localized to the mitochondrial matrix. Additionally, using RT-PCR, we confirmed the presence of α pore-forming (Slo1) and auxiliary β3-β4 subunits of BKCa channel in HBE cells. Western blot analysis of cellular fractions confirmed the mitochondrial localization of α pore-forming and predominately β3 subunits. Additionally, the regulation of oxygen consumption and membrane potential of human bronchial epithelial mitochondria in the presence of the potassium channel opener NS11021 and inhibitor paxilline were also studied. In summary, for the first time, the electrophysiological and functional properties of the mitoBKCa channel in a bronchial epithelial cell line were described.
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Affiliation(s)
- Aleksandra Sek
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.S.); (R.P.K.); (B.K.); (A.S.)
- Faculty of Chemistry, University of Warsaw, 02-093 Warsaw, Poland
| | - Rafal P. Kampa
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.S.); (R.P.K.); (B.K.); (A.S.)
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences—SGGW, 02-776 Warsaw, Poland
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.S.); (R.P.K.); (B.K.); (A.S.)
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.S.); (R.P.K.); (B.K.); (A.S.)
| | - Piotr Bednarczyk
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences—SGGW, 02-776 Warsaw, Poland
- Correspondence: ; Tel.: +48-22-593-8620
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10
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Gałecka S, Kulawiak B, Bednarczyk P, Singh H, Szewczyk A. Single channel properties of mitochondrial large conductance potassium channel formed by BK-VEDEC splice variant. Sci Rep 2021; 11:10925. [PMID: 34035423 PMCID: PMC8149700 DOI: 10.1038/s41598-021-90465-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 05/10/2021] [Indexed: 01/15/2023] Open
Abstract
The activation of mitochondrial large conductance calcium-activated potassium (mitoBKCa) channels increases cell survival during ischemia/reperfusion injury of cardiac cells. The basic biophysical and pharmacological properties of mitoBKCa correspond to the properties of the BKCa channels from the plasma membrane. It has been suggested that the VEDEC splice variant of the KCNMA1 gene product encoding plasma membrane BKCa is targeted toward mitochondria. However there has been no direct evidence that this protein forms a functional channel in mitochondria. In our study, we used HEK293T cells to express the VEDEC splice variant and observed channel activity in mitochondria using the mitoplast patch-clamp technique. For the first time, we found that transient expression with the VEDEC isoform resulted in channel activity with the conductance of 290 ± 3 pS. The channel was voltage-dependent and activated by calcium ions. Moreover, the activity of the channel was stimulated by the potassium channel opener NS11021 and inhibited by hemin and paxilline, which are known BKCa channel blockers. Immunofluorescence experiments confirmed the partial colocalization of the channel within the mitochondria. From these results, we conclude that the VEDEC isoform of the BKCa channel forms a functional channel in the inner mitochondrial membrane. Additionally, our data show that HEK293T cells are a promising experimental model for expression and electrophysiological studies of mitochondrial potassium channels.
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Affiliation(s)
- Shur Gałecka
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., 02-093, Warsaw, Poland
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., 02-093, Warsaw, Poland.
| | - Piotr Bednarczyk
- Department of Physics and Biophysics, Institute of Biology, Warsaw, University of Life Sciences-SGGW, Nowoursynowska 166, 02-787, Warsaw, Poland
| | - Harpreet Singh
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, 43210, USA
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., 02-093, Warsaw, Poland
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Rotko D, Kudin AP, Zsurka G, Kulawiak B, Szewczyk A, Kunz WS. Molecular and Functional Effects of Loss of Cytochrome c Oxidase Subunit 8A. Biochemistry (Mosc) 2021; 86:33-43. [PMID: 33705280 DOI: 10.1134/s0006297921010041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In this work we studied molecular and functional effects of the loss of the smallest nuclear encoded subunit of cytochrome c oxidase COX8A in fibroblasts from a patient with a homozygous splice site mutation and in CRISPR/Cas9 genome-edited HEK293T cells. In both cellular model systems, between 20 to 30% of the residual enzymatic activity of cytochrome c oxidase (COX) was detectable. In immunoblots of BN-PAGE separated mitochondria from both cellular models almost no monomers and dimers of the fully assembled COX could be visualized. Interestingly, supercomplexes of COX formed with complex III and also with complexes I and III retained considerable immunoreactivity, while nearly no immunoreactivity attributable to subassemblies was found. That indicates that COX lacking subunit 8A is stabilized in supercomplexes, while monomers and dimers are rapidly degraded. With transcriptome analysis by 3'-RNA sequencing we failed to detect in our cellular models of COX8A deficiency transcriptional changes of genes involved in the mitochondrial unfolded protein response (mtUPR) and the integrated stress response (ISR). Thus, our data strongly suggest that the smallest subunit of cytochrome c oxidase COX8A is required for maintenance of the structural stability of COX monomers and dimers.
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Affiliation(s)
- Daria Rotko
- Institute of Experimental Epileptology and Cognition Research, Life & Brain Center, University of Bonn, Venusberg-Campus 1, Bonn, 53127, Germany. .,Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, 02-093, Poland
| | - Alexei P Kudin
- Institute of Experimental Epileptology and Cognition Research, Life & Brain Center, University of Bonn, Venusberg-Campus 1, Bonn, 53127, Germany.
| | - Gábor Zsurka
- Institute of Experimental Epileptology and Cognition Research, Life & Brain Center, University of Bonn, Venusberg-Campus 1, Bonn, 53127, Germany. .,Department of Epileptology, University Bonn Medical Center, Venusberg-Campus 1, Bonn, 53127, Germany
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, 02-093, Poland.
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, 02-093, Poland.
| | - Wolfram S Kunz
- Institute of Experimental Epileptology and Cognition Research, Life & Brain Center, University of Bonn, Venusberg-Campus 1, Bonn, 53127, Germany. .,Department of Epileptology, University Bonn Medical Center, Venusberg-Campus 1, Bonn, 53127, Germany
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12
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Rotko D, Bednarczyk P, Koprowski P, Kunz WS, Szewczyk A, Kulawiak B. Heme is required for carbon monoxide activation of mitochondrial BK Ca channel. Eur J Pharmacol 2020; 881:173191. [PMID: 32422186 DOI: 10.1016/j.ejphar.2020.173191] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 05/07/2020] [Accepted: 05/11/2020] [Indexed: 11/24/2022]
Abstract
Carbon monoxide (CO) is an endogenously synthesized gaseous mediator and is involved in the regulation of numerous physiological processes. Mitochondria, in which hemoproteins are abundant, are among the targets for CO action. Large-conductance calcium-activated (mitoBKCa) channels in the inner mitochondrial membrane share multiple biophysical similarities with the BKCa channels of the plasma membrane and could be a potential target for CO. To test this hypothesis, the activity of the mitoBKCa channels in human astrocytoma U-87 MG cell mitochondria was assessed with the patch-clamp technique. The effects of CO-releasing molecules (CORMs), such as CORM-2, CORM-401, and CORM-A1, were compared to the application of a CO-saturated solution to the mitoBKCa channels in membrane patches. The applied CORMs showed pleiotropic effects including channel inhibition, while the CO-containing solution did not significantly modulate channel activity. Interestingly, CO applied to the mitoBKCa channels, which were inhibited by exogenously added heme, stimulated the channel. To summarize, our findings indicate a requirement of heme binding to the mitoBKCa channel for channel modulation by CO and suggest that CORMs might have complex unspecific effects on mitoBKCa channels.
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Affiliation(s)
- Daria Rotko
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pastuera 3, 02-093, Warsaw, Poland
| | - Piotr Bednarczyk
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Piotr Koprowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pastuera 3, 02-093, Warsaw, Poland
| | - Wolfram S Kunz
- Division of Neurochemistry, Department of Experimental Epileptology and Cognition Research University of Bonn, Sigmund-Freud Strasse 25, 53105, Bonn, Germany
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pastuera 3, 02-093, Warsaw, Poland
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pastuera 3, 02-093, Warsaw, Poland.
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Szewczyk A, Walewska A, Rotko D, Kulawiak B, Koprowski P. Mitochondrial Potassium Channels: Regulation by Gaseous Transmitter. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.1455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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14
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Kulawiak B, Karolina Kucman S, Jędraszko J, Bednarczyk P, Szewczyk AM. Single Channel Recordings of mitoBKCa Channel Formed by BK-Dec Splice Variant. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.1454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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15
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Szewczyk A, Bednarczyk P, Jędraszko J, Kampa RP, Koprowski P, Krajewska M, Kucman S, Kulawiak B, Laskowski M, Rotko D, Sęk A, Walewska A, Żochowska M, Wrzosek A. Mitochondrial potassium channels - an overview. Postepy Biochem 2018; 64:196-212. [PMID: 30656905 DOI: 10.18388/pb.2018_132] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 08/16/2018] [Indexed: 06/09/2023]
Abstract
Mitochondria play a fundamental role in ATP synthesis within the majority of mammalian cells. Potassium channels present in the inner mitochondrial membrane are fine regulators of mitochondrial function, based on inner membrane K+ permeability. These channels are regulated by a plethora of factors and conditions in a way similar to plasma membrane potassium channels. Regulators of mitochondrial potassium channels include the membrane potential, calcium ions, free fatty acids and ATP levels within the cells. Recently, it was shown that these channels are regulated by the respiratory chain, stretching of the membrane and phosphorylation. The essential interest that has driven studies of mitochondrial potassium channels for nearly 25 years is their role in cytoprotection and in cell death. Mitochondrial potassium channels have been described in neurons, astrocytoma, cardiac and skeletal muscles, fibroblasts, keratinocytes and endothelial cells. In this overview, we summarize the current knowledge of mitochondrial potassium channels. This summary will be done with a special focus on studies performed over the last 20 years in the Laboratory of Intracellular Ion Channels at the Nencki Institute. These include studies on the electrophysiological and pharmacological properties of mitochondrial potassium channels and on their regulation by endogenous intracellular substances. Additionally, the regulation of mitochondrial potassium channels by the respiratory chain and by stretching of the inner mitochondrial membrane will be reviewed. Properties of mitochondrial potassium channels in various organisms will also be summarized.
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Affiliation(s)
- Adam Szewczyk
- Instytut Biologii Doświadczalnej PAN im. M. Nenckiego w Warszawie
| | - Piotr Bednarczyk
- Katedra Fizyki, Szkoła Główna Gospodarstwa Wiejskiego w Warszawie, ul. Nowoursynowska 159, 02-776 Warszawa
| | | | | | - Piotr Koprowski
- Instytut Biologii Doświadczalnej PAN im. M. Nenckiego w Warszawie
| | - Milena Krajewska
- Instytut Biologii Doświadczalnej PAN im. M. Nenckiego w Warszawie
| | - Shur Kucman
- Instytut Biologii Doświadczalnej PAN im. M. Nenckiego w Warszawie
| | - Bogusz Kulawiak
- Instytut Biologii Doświadczalnej PAN im. M. Nenckiego w Warszawie
| | - Michał Laskowski
- Instytut Biologii Doświadczalnej PAN im. M. Nenckiego w Warszawie
| | - Daria Rotko
- Instytut Biologii Doświadczalnej PAN im. M. Nenckiego w Warszawie
| | - Aleksandra Sęk
- Instytut Biologii Doświadczalnej PAN im. M. Nenckiego w Warszawie
| | | | - Monika Żochowska
- Instytut Biologii Doświadczalnej PAN im. M. Nenckiego w Warszawie
| | - Antoni Wrzosek
- Instytut Biologii Doświadczalnej PAN im. M. Nenckiego w Warszawie
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Walewska A, Kulawiak B, Szewczyk A, Koprowski P. Mechanosensitivity of mitochondrial large-conductance calcium-activated potassium channels. Biochim Biophys Acta Bioenerg 2018; 1859:797-805. [PMID: 29775559 DOI: 10.1016/j.bbabio.2018.05.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 04/29/2018] [Accepted: 05/10/2018] [Indexed: 12/01/2022]
Abstract
Potassium channels have been discovered in the inner mitochondrial membrane of various cells. These channels can regulate the mitochondrial membrane potential, the matrix volume, respiration and reactive species generation. Therefore, it is believed that their activation is cytoprotective in various tissues. In our study, the single-channel activity of a large-conductance calcium-activated potassium channel (mitoBKCa) was measured by the patch-clamp technique on mitoplasts derived from mitochondria isolated from human glioma U-87 MG cells. Here, we show for the first time that mechanical stimulation of mitoBKCa channels results in an increased probability of channel opening. However, the mechanosensitivity of mitoBKCa channels was variable with some channels exhibiting no mechanosensitivity. We detected the expression of mechanosensitive BKCa-STREX exon in U-87 MG cells and hypotesize, based on previous studies demonstrating the presence of multiple BKCa splice variants that variable mechanosensitivity of mitoBKCa could be the result of the presence of diverse BKCa isoforms in mitochondria of U-87 MG cells. Our findings indicate the possible involvement of the mitoBKCa channel in mitochondria activities in which changes in membrane tension and shape play a crucial role, such as fusion/fission and cristae remodeling.
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Affiliation(s)
- Agnieszka Walewska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Piotr Koprowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland.
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17
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Bednarczyk P, Kicinska A, Laskowski M, Kulawiak B, Kampa R, Walewska A, Krajewska M, Jarmuszkiewicz W, Szewczyk A. Evidence for a mitochondrial ATP-regulated potassium channel in human dermal fibroblasts. Biochim Biophys Acta Bioenerg 2018; 1859:309-318. [PMID: 29458000 DOI: 10.1016/j.bbabio.2018.02.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 01/04/2018] [Accepted: 02/14/2018] [Indexed: 02/07/2023]
Abstract
Mitochondrial ATP-regulated potassium channels are present in the inner membrane of the mitochondria of various cells. In the present study, we show for the first time mitochondrial ATP-regulated potassium channels in human dermal fibroblast cells. Using the patch-clamp technique on the inner mitochondrial membrane of fibroblasts, we detected a potassium channel with a mean conductance equal to 100 pS in symmetric 150 mM KCl. The activity of this channel was inhibited by a complex of ATP/Mg2+ and activated by potassium channel openers such as diazoxide or BMS 191095. Channel activity was inhibited by antidiabetic sulfonylurea glibenclamide and 5-hydroxydecanoic acid. The influence of substances modulating ATP-regulated potassium channel activity on oxygen consumption and membrane potential of isolated fibroblast mitochondria was also studied. Additionally, the potassium channel opener diazoxide lowered the amount of superoxide formed in isolated fibroblast mitochondria. Using reverse transcriptase-PCR, we found an mRNA transcript for the KCNJ1(ROMK) channel. The presence of ROMK protein was observed in the inner mitochondrial membrane fraction. Moreover, colocalization of the ROMK protein and a mitochondrial marker in the mitochondria of fibroblast cells was shown by immunofluorescence. In summary, the ATP-regulated mitochondrial potassium channel in a dermal fibroblast cell line have been identified.
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Affiliation(s)
- Piotr Bednarczyk
- Department of Biophysics, Warsaw University of Life Sciences (SGGW), Warsaw, Poland.
| | - Anna Kicinska
- Department of Bioenergetics, Adam Mickiewicz University, Poznan, Poland
| | - Michal Laskowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Rafal Kampa
- Department of Biophysics, Warsaw University of Life Sciences (SGGW), Warsaw, Poland; Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Agnieszka Walewska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Milena Krajewska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Warsaw, Poland
| | | | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Warsaw, Poland
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18
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Szewczyk A, Kicinska A, Augustynek B, Kulawiak B, Jarmuszkiewicz W, Bednarczyk P. Identification of Large-Conductance Calcium-Regulated K Channel in Human Dermal Mitochndria. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.2197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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19
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Koprowski P, Kielbasa A, Kulawiak B, Szewczyk A. Mechanosensitivity of Mitochondrial Potassium Channels. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.2196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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20
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Laskowski M, Augustynek B, Kulawiak B, Koprowski P, Bednarczyk P, Jarmuszkiewicz W, Szewczyk A. What do we not know about mitochondrial potassium channels? Biochim Biophys Acta 2016; 1857:1247-1257. [PMID: 26951942 DOI: 10.1016/j.bbabio.2016.03.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 03/02/2016] [Accepted: 03/03/2016] [Indexed: 01/14/2023]
Abstract
In this review, we summarize our knowledge about mitochondrial potassium channels, with a special focus on unanswered questions in this field. The following potassium channels have been well described in the inner mitochondrial membrane: ATP-regulated potassium channel, Ca(2+)-activated potassium channel, the voltage-gated Kv1.3 potassium channel, and the two-pore domain TASK-3 potassium channel. The primary functional roles of these channels include regulation of mitochondrial respiration and the alteration of membrane potential. Additionally, they modulate the mitochondrial matrix volume and the synthesis of reactive oxygen species by mitochondria. Mitochondrial potassium channels are believed to contribute to cytoprotection and cell death. In this paper, we discuss fundamental issues concerning mitochondrial potassium channels: their molecular identity, channel pharmacology and functional properties. Attention will be given to the current problems present in our understanding of the nature of mitochondrial potassium channels. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.
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Affiliation(s)
- Michał Laskowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Bartłomiej Augustynek
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Piotr Koprowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Piotr Bednarczyk
- Department of Biophysics, Warsaw University of Life Sciences - SGGW, 159 Nowoursynowska St., 02-776 Warsaw, Poland
| | - Wieslawa Jarmuszkiewicz
- Laboratory of Bioenergetics, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland.
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21
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Laskowski M, Kulawiak B. [Topology of the mitochondrial potassium ion channels]. Postepy Biochem 2016; 62:199-205. [PMID: 28132472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 05/30/2016] [Indexed: 06/06/2023]
Abstract
In the inner mitochondrial membrane several potassium channels have been identified whose activation lead to cytoprotection during ischemic event. It was found that activation of mitochondrial large conductance calcium activated potassium channel (mitoBKCa) and ATP regulated potassium channel (mitoKATP) preserves brain and heart muscle cells against ischemia/reperfusion induced damage. However the detailed cytoprotection mechanism remains unclear. Similarly, the molecular structures and protein interactions of the mitochondrial potassium channels are still unknown. In this article, we summarize the current knowledge of the mitoKATP and mitoBKCa channels topology. Different aspects of this topic are discussed like import and assembly of the channel subunits and biophysical properties of mitochondrial compartments. Additionally, the consequences of different topology models on the cytoprotective function of the mitochondrial potassium channels were analyzed.
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Affiliation(s)
- Michał Laskowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., 02-093 Warsaw, Poland
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22
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Böttinger L, Guiard B, Oeljeklaus S, Kulawiak B, Zufall N, Wiedemann N, Warscheid B, van der Laan M, Becker T. A complex of Cox4 and mitochondrial Hsp70 plays an important role in the assembly of the cytochrome c oxidase. Mol Biol Cell 2013; 24:2609-19. [PMID: 23864706 PMCID: PMC3756914 DOI: 10.1091/mbc.e13-02-0106] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The biogenesis of Cox4 is unknown. Cox4, mtHsp70, and Mge1 form a complex that promotes the assembly of cytochrome c oxidase. In the absence of the mature cytochrome c oxidase, Cox4 arrests at the chaperone complex. This complex delivers Cox4 into the assembly line of complex IV when needed. The formation of the mature cytochrome c oxidase (complex IV) involves the association of nuclear- and mitochondria-encoded subunits. The assembly of nuclear-encoded subunits like cytochrome c oxidase subunit 4 (Cox4) into the mature complex is poorly understood. Cox4 is crucial for the stability of complex IV. To find specific biogenesis factors, we analyze interaction partners of Cox4 by affinity purification and mass spectroscopy. Surprisingly, we identify a complex of Cox4, the mitochondrial Hsp70 (mtHsp70), and its nucleotide-exchange factor mitochondrial GrpE (Mge1). We generate a yeast mutant of mtHsp70 specifically impaired in the formation of this novel mtHsp70-Mge1-Cox4 complex. Strikingly, the assembly of Cox4 is strongly decreased in these mutant mitochondria. Because Cox4 is a key factor for the biogenesis of complex IV, we conclude that the mtHsp70-Mge1-Cox4 complex plays an important role in the formation of cytochrome c oxidase. Cox4 arrests at this chaperone complex in the absence of mature complex IV. Thus the mtHsp70-Cox4 complex likely serves as a novel delivery system to channel Cox4 into the assembly line when needed.
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Affiliation(s)
- Lena Böttinger
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany
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23
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Kulawiak B, Höpker J, Gebert M, Guiard B, Wiedemann N, Gebert N. The mitochondrial protein import machinery has multiple connections to the respiratory chain. Biochim Biophys Acta 2012; 1827:612-26. [PMID: 23274250 DOI: 10.1016/j.bbabio.2012.12.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 12/12/2012] [Accepted: 12/17/2012] [Indexed: 01/09/2023]
Abstract
The mitochondrial inner membrane harbors the complexes of the respiratory chain and protein translocases required for the import of mitochondrial precursor proteins. These complexes are functionally interdependent, as the import of respiratory chain precursor proteins across and into the inner membrane requires the membrane potential. Vice versa the membrane potential is generated by the proton pumping complexes of the respiratory chain. Besides this basic codependency four different systems for protein import, processing and assembly show further connections to the respiratory chain. The mitochondrial intermembrane space import and assembly machinery oxidizes cysteine residues within the imported precursor proteins and is able to donate the liberated electrons to the respiratory chain. The presequence translocase of the inner membrane physically interacts with the respiratory chain. The mitochondrial processing peptidase is homologous to respiratory chain subunits and the carrier translocase of the inner membrane even shares a subunit with the respiratory chain. In this review we will summarize the import of mitochondrial precursor proteins and highlight these special links between the mitochondrial protein import machinery and the respiratory chain. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.
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Affiliation(s)
- Bogusz Kulawiak
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, Freiburg, Germany
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Gebert N, Gebert M, Oeljeklaus S, von der Malsburg K, Stroud D, Kulawiak B, Wirth C, Zahedi R, Dolezal P, Wiese S, Simon O, Schulze-Specking A, Truscott K, Sickmann A, Rehling P, Guiard B, Hunte C, Warscheid B, van der Laan M, Pfanner N, Wiedemann N. Dual Function of Sdh3 in the Respiratory Chain and TIM22 Protein Translocase of the Mitochondrial Inner Membrane. Mol Cell 2011; 44:811-8. [DOI: 10.1016/j.molcel.2011.09.025] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 08/18/2011] [Accepted: 09/20/2011] [Indexed: 10/14/2022]
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25
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Malinska D, Kulawiak B, Wrzosek A, Kunz WS, Szewczyk A. The cytoprotective action of the potassium channel opener BMS-191095 in C2C12 myoblasts is related to the modulation of calcium homeostasis. Cell Physiol Biochem 2010; 26:235-46. [PMID: 20798507 DOI: 10.1159/000320523] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2010] [Indexed: 11/19/2022] Open
Abstract
UNLABELLED BMS-191095 is an opener of the mitochondrial ATP-regulated potassium channel, which has been shown to provide cytoprotection in models of ischemia-reperfusion induced injury in various tissues. This study aimed at checking the protective action of BMS-191095 under the conditions of oxidative stress or disruption of intracellular calcium homeostasis. METHODS The cytoprotective potential of BMS-191095 was tested in C2C12 myoblasts injured by treatment with H(2)O(2) or calcium ionophore A23187. The influence of the opener on intracellular calcium levels, calpain activity and respiration rates were determined. RESULTS BMS-191095 protected myoblasts from calcium ionophore A23187-induced injury, but not from H H(2)O(2)-induced injury. A23187-mediated cell damage was also prevented by calpain inhibitor PD 150606. A23187 administration led to a transient increase in cytosolic calcium levels, concomitant activation of calpains and a decrease in state 3 respiration rates, indicating mitochondrial dysfunction. Co-administration of BMS-191095 diminished calpain activation in A23187-treated cells but did not prevent mitochondrial damage. In the presence of BMS-191095, restoration of cytosolic calcium concentrations to basal levels after A23187 treatment was considerably faster which may underly the reduced activation of calpains. CONCLUSION The BMS-191095-mediated cytoprotection observed in C2C12 myoblasts results probably from modulation of intracellular calcium transients leading to prevention of calpain activation.
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Affiliation(s)
- Dominika Malinska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Warsaw, Poland
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Malinska D, Kulawiak B, Kudin AP, Kovacs R, Huchzermeyer C, Kann O, Szewczyk A, Kunz WS. Complex III-dependent superoxide production of brain mitochondria contributes to seizure-related ROS formation. Biochimica et Biophysica Acta (BBA) - Bioenergetics 2010; 1797:1163-70. [DOI: 10.1016/j.bbabio.2010.03.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 02/19/2010] [Accepted: 03/01/2010] [Indexed: 01/16/2023]
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Debska-Vielhaber G, Godlewski MM, Kicinska A, Skalska J, Kulawiak B, Piwonska M, Zablocki K, Kunz WS, Szewczyk A, Motyl T. Large-conductance K+ channel openers induce death of human glioma cells. J Physiol Pharmacol 2009; 60:27-36. [PMID: 20065494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Accepted: 11/06/2009] [Indexed: 05/28/2023]
Abstract
Large-conductance Ca(2+)-activated K(+) channels (BKCa channels) are highly expressed in human glioma cells. It has been reported that BK(Ca) channels are present in the inner mitochondrial membrane of the human glioma cell line LN229. In the present study we investigated whether BK(Ca)-channel openers, such as CGS7181 (ethyl 2-hydroxy-1-[[(4-methylphenyl)amino]oxo]-6-trifluoromethyl-1H-indole-3-carboxylate) and CGS7184 (ethyl 1-[[(4-chlorophenyl)amino]oxo]-2-hydroxy-6-trifluoromethyl-1H-indole-3-carboxylate), affect the functioning of LN229 glioma cell mitochondria in situ. In the micromolar concentration range CGS7181 and CGS7184 induced glioma cell death. Morphological and cytometric analyses confirmed that both substances trigger the glioma cell death. This effect was not inhibited by the pan-caspase inhibitor z-VAD-fmk. Lack of DNA laddering, PARP cleavage, and caspase 3 activation suggested that glioma cell death was not of the apoptotic type. We examined the effect of CGS7184 on mitochondrial membrane potential and mitochondrial respiration. Potassium channel opener CGS7184 increased cell respiration and induced mitochondrial membrane depolarization. The latter was dependent on the presence of Ca(2+) in the external medium. It was shown that CGS7184 induced an increase of cytosolic Ca(2+) concentration due to endoplasmic reticulum store depletion. In conclusion, our results show that CGS7181 and CGS7184 induce glioma cell death by increasing the cytosolic calcium concentration followed by activation of calpains.
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Affiliation(s)
- G Debska-Vielhaber
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Warsaw, Poland
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Choma K, Bednarczyk P, Koszela-Piotrowska I, Kulawiak B, Kudin A, Kunz WS, Dołowy K, Szewczyk A. Single channel studies of the ATP-regulated potassium channel in brain mitochondria. J Bioenerg Biomembr 2009; 41:323-34. [PMID: 19821034 DOI: 10.1007/s10863-009-9233-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 07/21/2009] [Indexed: 01/17/2023]
Abstract
Mitochondrial potassium channels in the brain have been suggested to have an important role in neuroprotection. The single channel activity of mitochondrial potassium channels was measured after reconstitution of the purified inner membrane from rat brain mitochondria into a planar lipid bilayer. In addition to a large conductance potassium channel that was described previously, we identified a potassium channel that has a mean conductance of 219 +/- 15 pS. The activity of this channel was inhibited by ATP/Mg(2+) and activated by the potassium channel opener BMS191095. Channel activity was not influenced either by 5-hydroxydecanoic acid, an inhibitor of mitochondrial ATP-regulated potassium channels, or by the plasma membrane ATP-regulated potassium channel blocker HMR1098. Likewise, this mitochondrial potassium channel was unaffected by the large conductance potassium channel inhibitor iberiotoxin or by the voltage-dependent potassium channel inhibitor margatoxin. The amplitude of the conductance was lowered by magnesium ions, but the opening ability was unaffected. Immunological studies identified the Kir6.1 channel subunit in the inner membrane from rat brain mitochondria. Taken together, our results demonstrate for the first time the single channel activity and properties of an ATP-regulated potassium channel from rat brain mitochondria.
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Affiliation(s)
- Katarzyna Choma
- Department of Biophysics, Warsaw University of Life Sciences SGGW, 159 Nowoursynowska St., 02-776, Warsaw, Poland
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Skalska J, Bednarczyk P, Piwońska M, Kulawiak B, Wilczynski G, Dołowy K, Kudin AP, Kunz WS, Szewczyk A. Calcium ions regulate K⁺ uptake into brain mitochondria: the evidence for a novel potassium channel. Int J Mol Sci 2009; 10:1104-20. [PMID: 19399240 PMCID: PMC2672021 DOI: 10.3390/ijms10031104] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Revised: 03/06/2009] [Accepted: 03/10/2009] [Indexed: 11/28/2022] Open
Abstract
The mitochondrial response to changes of cytosolic calcium concentration has a strong impact on neuronal cell metabolism and viability. We observed that Ca(2+) additions to isolated rat brain mitochondria induced in potassium ion containing media a mitochondrial membrane potential depolarization and an accompanying increase of mitochondrial respiration. These Ca(2+) effects can be blocked by iberiotoxin and charybdotoxin, well known inhibitors of large conductance potassium channel (BK(Ca) channel). Furthermore, NS1619 - a BK(Ca) channel opener - induced potassium ion-specific effects on brain mitochondria similar to those induced by Ca(2+). These findings suggest the presence of a calcium-activated, large conductance potassium channel (sensitive to charybdotoxin and NS1619), which was confirmed by reconstitution of the mitochondrial inner membrane into planar lipid bilayers. The conductance of the reconstituted channel was 265 pS under gradient (50/450 mM KCl) conditions. Its reversal potential was equal to 50 mV, which proved that the examined channel was cation-selective. We also observed immunoreactivity of anti-beta(4) subunit (of the BK(Ca) channel) antibodies with ~26 kDa proteins of rat brain mitochondria. Immunohistochemical analysis confirmed the predominant occurrence of beta(4) subunit in neuronal mitochondria. We hypothesize that the mitochondrial BK(Ca) channel represents a calcium sensor, which can contribute to neuronal signal transduction and survival.
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Affiliation(s)
- Jolanta Skalska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur st., 02–093 Warsaw, Poland; E-Mails:
(J.S.);
(P.B.);
(M.P.);
(B.K.);
(A.S.)
| | - Piotr Bednarczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur st., 02–093 Warsaw, Poland; E-Mails:
(J.S.);
(P.B.);
(M.P.);
(B.K.);
(A.S.)
- Department of Biophysics, Agricultural University SGGW, 159 Nowoursynowska St., 02–776 Warsaw, Poland; E-Mail:
| | - Marta Piwońska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur st., 02–093 Warsaw, Poland; E-Mails:
(J.S.);
(P.B.);
(M.P.);
(B.K.);
(A.S.)
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur st., 02–093 Warsaw, Poland; E-Mails:
(J.S.);
(P.B.);
(M.P.);
(B.K.);
(A.S.)
| | - Grzegorz Wilczynski
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, 3 Pasteur st., 02–093 Warsaw, Poland; E-Mail:
| | - Krzysztof Dołowy
- Department of Biophysics, Agricultural University SGGW, 159 Nowoursynowska St., 02–776 Warsaw, Poland; E-Mail:
| | - Alexei P. Kudin
- Division of Neurochemistry, Department of Epileptology and Life&Brain Center, University Bonn Medical Center, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany; E-Mail:
| | - Wolfram S. Kunz
- Division of Neurochemistry, Department of Epileptology and Life&Brain Center, University Bonn Medical Center, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany; E-Mail:
- Author to whom correspondence should be addressed; E-Mail:
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur st., 02–093 Warsaw, Poland; E-Mails:
(J.S.);
(P.B.);
(M.P.);
(B.K.);
(A.S.)
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Kulawiak B, Kudin AP, Szewczyk A, Kunz WS. BK channel openers inhibit ROS production of isolated rat brain mitochondria. Exp Neurol 2008; 212:543-7. [PMID: 18572168 DOI: 10.1016/j.expneurol.2008.05.004] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Revised: 04/23/2008] [Accepted: 05/10/2008] [Indexed: 11/26/2022]
Abstract
To delineate the potential mechanism of neuroprotective effects of potassium channel openers we have investigated, how Ca(2+)-activated large conductance potassium channel (BK(Ca) channel) openers influence the production of reactive oxygen species (ROS) by rat brain mitochondria, since mitochondrial generation of ROS is known to have a crucial influence on neuronal survival. We studied the effects of BK(Ca) channel openers CGS 7184 and NS 1619 on hydrogen peroxide production rate of isolated rat brain mitochondria. In K(+)-containing media 3 microM of both channel openers reduced the hydrogen peroxide production rates by approximately 20%. This effect was not observed in Na(+)-containing media. This potassium-dependent partial inhibition of hydrogen peroxide production was found to be sensitive to the selective blockers of BK(Ca) channel iberiotoxin and charybdotoxin applied in nanomolar concentrations. Taken together, our data are compatible with the viewpoint that the opening of a Ca(2+)-activated large conductance potassium channel being localised in the inner membrane of brain mitochondria inhibits ROS production by respiratory chain complex I. This finding is suggested to explain the beneficial effects of BK potassium channel openers on neuronal survival.
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Affiliation(s)
- Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland
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Szewczyk A, Skalska J, Głab M, Kulawiak B, Malińska D, Koszela-Piotrowska I, Kunz WS. Mitochondrial potassium channels: from pharmacology to function. Biochim Biophys Acta 2006; 1757:715-20. [PMID: 16787636 DOI: 10.1016/j.bbabio.2006.05.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Revised: 04/19/2006] [Accepted: 05/02/2006] [Indexed: 11/20/2022]
Abstract
Mitochondrial potassium channels, such as ATP-regulated or large conductance Ca2+ -activated and voltage gated channels were implicated in cytoprotective phenomenon in different tissues. Basic effects of these channels activity include changes in mitochondrial matrix volume, mitochondrial respiration and membrane potential, and generation of reactive oxygen species. In this paper, we describe the pharmacological properties of mitochondrial potassium channels and their modulation by channel inhibitors and potassium channel openers. We also discuss potential side effects of these substances.
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Affiliation(s)
- Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur st., 02-093 Warsaw, Poland.
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Skalska J, Debska-Vielhaber G, Głab M, Kulawiak B, Malińska D, Koszela-Piotrowska I, Bednarczyk P, Dołowy K, Szewczyk A. [Mitochondrial ion channels]. Postepy Biochem 2006; 52:137-44. [PMID: 17078503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Ion channels are proteins, which facilitate the ions flow throught biological membranes. In recent years the structure as well as the function of the plasma membrane ion channels have been well investigated. The knowledge of intracellular ion channels however is still poor. Up till now, the calcium channel described in endoplasmatic reticulum and mitochondrial porine are the examples of intracellular ion channels, which have been well characterized. The mitochondrial potassium channels: regulated by ATP (mitoK(ATP)) and of big conductance activated by Ca2+ (mitoBK(Ca)), which were described in inner mitochondrial membrane, play a key role in the protection of heart muscle against ischemia. In this review the last date concerning the mitochondrial ion channels as well as they function in cell metabolism have been presented.
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Affiliation(s)
- Jolanta Skalska
- Pracownia Wewnatrzkomórkowych Kanałów Jonowych, Instytut Biologii Doświadczalnej PAN im. Marcelego Nenckiego, Warszawa
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Kulawiak B, Bednarczyk P. Reconstitution of brain mitochondria inner membrane into planar lipid bilayer. Acta Neurobiol Exp (Wars) 2005; 65:271-6. [PMID: 16130801 DOI: 10.55782/ane-2005-1562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Ion channels are present in the inner mitochondrial membrane. They play an important role in cellular processes. Potassium and chloride channels are involved in regulation of mitochondrial volume, membrane potential and acidification. The mitochondrial potassium channels have been suggested as triggers and end effectors in cytoprotection. In our study we measured single channel activities after reconstitution of submitochondrial particles from rat brain mitochondria into planar lipid membranes. After incorporation, two different potassium selective currents were recorded with single channel conductance from 260 to 320 pS and from 70 to 90 pS in gradient (cis/trans) 50/450 and 50/150 mM KCl solutions, respectively. We also observed activity of the chloride ion channel. The measured single channel conductance was from 80 to 90 pS in gradient (cis/trans) 50/450 mM KCl solution. Our results suggest that various ion channels are present in the inner mitochondrial membrane of brain mitochondria.
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Affiliation(s)
- Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
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