1
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Asrani P, Seebohm G, Stoll R. Potassium viroporins as model systems for understanding eukaryotic ion channel behaviour. Virus Res 2022; 320:198903. [PMID: 36037849 DOI: 10.1016/j.virusres.2022.198903] [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] [Received: 03/14/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 11/29/2022]
Abstract
Ion channels are membrane proteins essential for a plethora of cellular functions including maintaining cell shape, ion homeostasis, cardiac rhythm and action potential in neurons. The complexity and often extensive structure of eukaryotic membrane proteins makes it difficult to understand their basic biological regulation. Therefore, this article suggests, viroporins - the miniature versions of eukaryotic protein homologs from viruses - might serve as model systems to provide insights into behaviour of eukaryotic ion channels in general. The structural requirements for correct assembly of the channel along with the basic functional properties of a K+ channel exist in the minimal design of the viral K+ channels from two viruses, Chlorella virus (Kcv) and Ectocarpus siliculosus virus (Kesv). These small viral proteins readily assemble into tetramers and they sort in cells to distinct target membranes. When these viruses-encoded channels are expressed into the mammalian cells, they utilise their protein machinery and hence can serve as excellent tools to study the cells protein sorting machinery. This combination of small size and robust function makes viral K+ channels a valuable model system for detection of basic structure-function correlations. It is believed that molecular and physiochemical analyses of these viroporins may serve as basis for the development of inhibitors or modulators to ion channel activity for targeting ion channel diseases - so called channelopathies. Therefore, it may provide a potential different scope for molecular pharmacology studies aiming at novel and innovative therapeutics associated with channel related diseases. This article reviews the structural and functional properties of Kcv and Kesv upon expression in mammalian cells and Xenopus oocytes. The mechanisms behind differential protein sorting in Kcv and Kesv are also thoroughly discussed.
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Affiliation(s)
- Purva Asrani
- Biomolecular Spectroscopy and RUBiospec|NMR, Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Bochum D-44780, Germany
| | - Guiscard Seebohm
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Münster D-48149, Germany
| | - Raphael Stoll
- Biomolecular Spectroscopy and RUBiospec|NMR, Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Bochum D-44780, Germany.
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2
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Kulawiak B, Szewczyk A. Current Challenges of Mitochondrial Potassium Channel Research. Front Physiol 2022; 13:907015. [PMID: 35711307 PMCID: PMC9193220 DOI: 10.3389/fphys.2022.907015] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
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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3
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Capera J, Navarro-Pérez M, Moen AS, Szabó I, Felipe A. The Mitochondrial Routing of the Kv1.3 Channel. Front Oncol 2022; 12:865686. [PMID: 35402277 PMCID: PMC8990977 DOI: 10.3389/fonc.2022.865686] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 03/02/2022] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated potassium channels control neuronal excitability and cardiac action potentials. In addition, these proteins are involved in a myriad of cellular processes. The potassium channel Kv1.3 plays an essential role in the immune response mediated by leukocytes. Kv1.3 is functional both at the plasma membrane and the inner mitochondrial membrane. Plasma membrane Kv1.3 mediates cellular activation and proliferation, whereas mitochondrial Kv1.3 participates in cell survival and apoptosis. Therefore, this protein emerges as an important target in cancer therapies. Several forward-traffic motifs target the channel to the plasma membrane in a COPII-dependent manner. However, the mitochondrial import pathway for Kv1.3 is largely unknown. Here, we deciphered the mitochondrial routing of the mitoKv1.3 channel. Kv1.3 uses the TIM23 complex to translocate to the inner mitochondrial membrane. This mechanism is unconventional because the channel is a multimembrane spanning protein without a defined N-terminal presequence. We found that transmembrane domains cooperatively mediate Kv1.3 mitochondrial targeting and identified the cytosolic HSP70/HSP90 chaperone complex as a key regulator of the process. Our results provide insights into the mechanisms mediating the localization of Kv1.3 to mitochondrial membranes, further extending the knowledge of ion channel biogenesis and turnover in mitochondria.
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Affiliation(s)
- Jesusa Capera
- Molecular Physiology Laboratory, Dpt. de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain.,Kennedy Institute of Rheumatology, University of Oxford, Oxford, United Kingdom
| | - María Navarro-Pérez
- Molecular Physiology Laboratory, Dpt. de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Anne Stine Moen
- Molecular Physiology Laboratory, Dpt. de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Ildiko Szabó
- Department of Biology, University of Padova, Padova, Italy
| | - Antonio Felipe
- Molecular Physiology Laboratory, Dpt. de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
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4
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Engel AJ, Kithil M, Langhans M, Rauh O, Cartolano M, Van Etten JL, Moroni A, Thiel G. Codon Bias Can Determine Sorting of a Potassium Channel Protein. Cells 2021; 10:cells10051128. [PMID: 34066987 PMCID: PMC8151079 DOI: 10.3390/cells10051128] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 11/27/2022] Open
Abstract
Due to the redundancy of the genetic code most amino acids are encoded by multiple synonymous codons. It has been proposed that a biased frequency of synonymous codons can affect the function of proteins by modulating distinct steps in transcription, translation and folding. Here, we use two similar prototype K+ channels as model systems to examine whether codon choice has an impact on protein sorting. By monitoring transient expression of GFP-tagged channels in mammalian cells, we find that one of the two channels is sorted in a codon and cell cycle-dependent manner either to mitochondria or the secretory pathway. The data establish that a gene with either rare or frequent codons serves, together with a cell-state-dependent decoding mechanism, as a secondary code for sorting intracellular membrane proteins.
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Affiliation(s)
- Anja J. Engel
- Membrane Biophysics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany; (A.J.E.); (M.K.); (M.L.); (O.R.); (M.C.)
| | - Marina Kithil
- Membrane Biophysics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany; (A.J.E.); (M.K.); (M.L.); (O.R.); (M.C.)
| | - Markus Langhans
- Membrane Biophysics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany; (A.J.E.); (M.K.); (M.L.); (O.R.); (M.C.)
| | - Oliver Rauh
- Membrane Biophysics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany; (A.J.E.); (M.K.); (M.L.); (O.R.); (M.C.)
| | - Matea Cartolano
- Membrane Biophysics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany; (A.J.E.); (M.K.); (M.L.); (O.R.); (M.C.)
| | - James L. Van Etten
- Nebraska Center for Virology, Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE 68583, USA;
| | - Anna Moroni
- Department of Biosciences, University of Milan, 20133 Milan, Italy;
| | - Gerhard Thiel
- Membrane Biophysics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany; (A.J.E.); (M.K.); (M.L.); (O.R.); (M.C.)
- Correspondence: ; Tel.: +49-61511621940
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5
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Van Etten JL, Agarkova IV, Dunigan DD. Chloroviruses. Viruses 2019; 12:E20. [PMID: 31878033 PMCID: PMC7019647 DOI: 10.3390/v12010020] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/13/2019] [Accepted: 12/15/2019] [Indexed: 12/20/2022] Open
Abstract
Chloroviruses are large dsDNA, plaque-forming viruses that infect certain chlorella-like green algae; the algae are normally mutualistic endosymbionts of protists and metazoans and are often referred to as zoochlorellae. The viruses are ubiquitous in inland aqueous environments throughout the world and occasionally single types reach titers of thousands of plaque-forming units per ml of native water. The viruses are icosahedral in shape with a spike structure located at one of the vertices. They contain an internal membrane that is required for infectivity. The viral genomes are 290 to 370 kb in size, which encode up to 16 tRNAs and 330 to ~415 proteins, including many not previously seen in viruses. Examples include genes encoding DNA restriction and modification enzymes, hyaluronan and chitin biosynthetic enzymes, polyamine biosynthetic enzymes, ion channel and transport proteins, and enzymes involved in the glycan synthesis of the virus major capsid glycoproteins. The proteins encoded by many of these viruses are often the smallest or among the smallest proteins of their class. Consequently, some of the viral proteins are the subject of intensive biochemical and structural investigation.
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Affiliation(s)
- James L. Van Etten
- Department of Plant Pathology, Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE 68583-0900, USA; (I.V.A.); (D.D.D.)
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6
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Biasutto L, Mattarei A, La Spina M, Azzolini M, Parrasia S, Szabò I, Zoratti M. Strategies to target bioactive molecules to subcellular compartments. Focus on natural compounds. Eur J Med Chem 2019; 181:111557. [PMID: 31374419 DOI: 10.1016/j.ejmech.2019.07.060] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 07/04/2019] [Accepted: 07/21/2019] [Indexed: 02/06/2023]
Abstract
Many potential pharmacological targets are present in multiple subcellular compartments and have different pathophysiological roles depending on location. In these cases, selective targeting of a drug to the relevant subcellular domain(s) may help to sharpen its impact by providing topological specificity, thus limiting side effects, and to concentrate the compound where needed, thus increasing its effectiveness. We review here the state of the art in precision subcellular delivery. The major approaches confer "homing" properties to the active principle via permanent or reversible (in pro-drug fashion) modifications, or through the use of special-design nanoparticles or liposomes to ferry a drug(s) cargo to its desired destination. An assortment of peptides, substituents with delocalized positive charges, custom-blended lipid mixtures, pH- or enzyme-sensitive groups provide the main tools of the trade. Mitochondria, lysosomes and the cell membrane may be mentioned as the fronts on which the most significant advances have been made. Most of the examples presented here have to do with targeting natural compounds - in particular polyphenols, known as pleiotropic agents - to one or the other subcellular compartment.
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Affiliation(s)
- Lucia Biasutto
- CNR Neuroscience Institute, Viale G. Colombo 3, 35121, Padova, Italy; Dept. Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121, Padova, Italy.
| | - Andrea Mattarei
- Dept. Pharmaceutical and Pharmacological Sciences, University of Padova, Via Marzolo 5, 35131, Padova, Italy
| | - Martina La Spina
- Dept. Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121, Padova, Italy
| | - Michele Azzolini
- Dept. Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121, Padova, Italy
| | - Sofia Parrasia
- Dept. Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121, Padova, Italy
| | - Ildikò Szabò
- CNR Neuroscience Institute, Viale G. Colombo 3, 35121, Padova, Italy; Dept. Biology, University of Padova, Viale G. Colombo 3, 35121, Padova, Italy
| | - Mario Zoratti
- CNR Neuroscience Institute, Viale G. Colombo 3, 35121, Padova, Italy; Dept. Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121, Padova, Italy
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7
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Capera J, Serrano-Novillo C, Navarro-Pérez M, Cassinelli S, Felipe A. The Potassium Channel Odyssey: Mechanisms of Traffic and Membrane Arrangement. Int J Mol Sci 2019; 20:ijms20030734. [PMID: 30744118 PMCID: PMC6386995 DOI: 10.3390/ijms20030734] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/06/2019] [Accepted: 02/08/2019] [Indexed: 12/29/2022] Open
Abstract
Ion channels are transmembrane proteins that conduct specific ions across biological membranes. Ion channels are present at the onset of many cellular processes, and their malfunction triggers severe pathologies. Potassium channels (KChs) share a highly conserved signature that is necessary to conduct K⁺ through the pore region. To be functional, KChs require an exquisite regulation of their subcellular location and abundance. A wide repertoire of signatures facilitates the proper targeting of the channel, fine-tuning the balance that determines traffic and location. These signature motifs can be part of the secondary or tertiary structure of the protein and are spread throughout the entire sequence. Furthermore, the association of the pore-forming subunits with different ancillary proteins forms functional complexes. These partners can modulate traffic and activity by adding their own signatures as well as by exposing or masking the existing ones. Post-translational modifications (PTMs) add a further dimension to traffic regulation. Therefore, the fate of a KCh is not fully dependent on a gene sequence but on the balance of many other factors regulating traffic. In this review, we assemble recent evidence contributing to our understanding of the spatial expression of KChs in mammalian cells. We compile specific signatures, PTMs, and associations that govern the destination of a functional channel.
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Affiliation(s)
- Jesusa Capera
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - Clara Serrano-Novillo
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - María Navarro-Pérez
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - Silvia Cassinelli
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - Antonio Felipe
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
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8
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Leanza L, Checchetto V, Biasutto L, Rossa A, Costa R, Bachmann M, Zoratti M, Szabo I. Pharmacological modulation of mitochondrial ion channels. Br J Pharmacol 2019; 176:4258-4283. [PMID: 30440086 DOI: 10.1111/bph.14544] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 10/15/2018] [Accepted: 10/22/2018] [Indexed: 12/17/2022] Open
Abstract
The field of mitochondrial ion channels has undergone a rapid development during the last three decades, due to the molecular identification of some of the channels residing in the outer and inner membranes. Relevant information about the function of these channels in physiological and pathological settings was gained thanks to genetic models for a few, mitochondria-specific channels. However, many ion channels have multiple localizations within the cell, hampering a clear-cut determination of their function by pharmacological means. The present review summarizes our current knowledge about the ins and outs of mitochondrial ion channels, with special focus on the channels that have received much attention in recent years, namely, the voltage-dependent anion channels, the permeability transition pore (also called mitochondrial megachannel), the mitochondrial calcium uniporter and some of the inner membrane-located potassium channels. In addition, possible strategies to overcome the difficulties of specifically targeting mitochondrial channels versus their counterparts active in other membranes are discussed, as well as the possibilities of modulating channel function by small peptides that compete for binding with protein interacting partners. Altogether, these promising tools along with large-scale chemical screenings set up to identify new, specific channel modulators will hopefully allow us to pinpoint the actual function of most mitochondrial ion channels in the near future and to pharmacologically affect important pathologies in which they are involved, such as neurodegeneration, ischaemic damage and cancer. LINKED ARTICLES: This article is part of a themed section on Mitochondrial Pharmacology: Featured Mechanisms and Approaches for Therapy Translation. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.22/issuetoc.
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Affiliation(s)
- Luigi Leanza
- Department of Biology, University of Padova, Padova, Italy
| | | | - Lucia Biasutto
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Andrea Rossa
- Department of Chemical Sciences, University of Padova, Padova, Italy
| | - Roberto Costa
- Department of Biology, University of Padova, Padova, Italy
| | | | - Mario Zoratti
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Ildiko Szabo
- Department of Biology, University of Padova, Padova, Italy.,CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Padova, Italy
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9
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Cotranslational Intersection between the SRP and GET Targeting Pathways to the Endoplasmic Reticulum of Saccharomyces cerevisiae. Mol Cell Biol 2016; 36:2374-83. [PMID: 27354063 DOI: 10.1128/mcb.00131-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 06/17/2016] [Indexed: 01/21/2023] Open
Abstract
Targeting of transmembrane proteins to the endoplasmic reticulum (ER) proceeds via either the signal recognition particle (SRP) or the guided entry of tail-anchored proteins (GET) pathway, consisting of Get1 to -5 and Sgt2. While SRP cotranslationally targets membrane proteins containing one or multiple transmembrane domains, the GET pathway posttranslationally targets proteins containing a single C-terminal transmembrane domain termed the tail anchor. Here, we dissect the roles of the SRP and GET pathways in the sorting of homologous, two-membrane-spanning K(+) channel proteins termed Kcv, Kesv, and Kesv-VV. We show that Kcv is targeted to the ER cotranslationally via its N-terminal transmembrane domain, while Kesv-VV is targeted posttranslationally via its C-terminal transmembrane domain, which recruits Get4-5/Sgt2 and Get3. Unexpectedly, nascent Kcv recruited not only SRP but also the Get4-5 module of the GET pathway to ribosomes. Ribosome binding of Get4-5 was independent of Sgt2 and was strongly outcompeted by SRP. The combined data indicate a previously unrecognized cotranslational interplay between the SRP and GET pathways.
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10
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Checchetto V, Teardo E, Carraretto L, Leanza L, Szabo I. Physiology of intracellular potassium channels: A unifying role as mediators of counterion fluxes? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1258-1266. [PMID: 26970213 DOI: 10.1016/j.bbabio.2016.03.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Revised: 03/06/2016] [Accepted: 03/07/2016] [Indexed: 12/28/2022]
Abstract
Plasma membrane potassium channels importantly contribute to maintain ion homeostasis across the cell membrane. The view is emerging that also those residing in intracellular membranes play pivotal roles for the coordination of correct cell function. In this review we critically discuss our current understanding of the nature and physiological tasks of potassium channels in organelle membranes in both animal and plant cells, with a special emphasis on their function in the regulation of photosynthesis and mitochondrial respiration. In addition, the emerging role of potassium channels in the nuclear membranes in regulating transcription will be discussed. The possible functions of endoplasmic reticulum-, lysosome- and plant vacuolar membrane-located channels are also referred to. Altogether, experimental evidence obtained with distinct channels in different membrane systems points to a possible unifying function of most intracellular potassium channels in counterbalancing the movement of other ions including protons and calcium and modulating membrane potential, thereby fine-tuning crucial cellular processes. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-7, 2016', edited by Prof. Paolo Bernardi.
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Affiliation(s)
- Vanessa Checchetto
- Department of Biology, University of Padova, Viale G. Colombo 3, Padova 35131, Italy; Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35131 Italy
| | - Enrico Teardo
- Department of Biology, University of Padova, Viale G. Colombo 3, Padova 35131, Italy
| | - Luca Carraretto
- Department of Biology, University of Padova, Viale G. Colombo 3, Padova 35131, Italy
| | - Luigi Leanza
- Department of Biology, University of Padova, Viale G. Colombo 3, Padova 35131, Italy
| | - Ildiko Szabo
- Department of Biology, University of Padova, Viale G. Colombo 3, Padova 35131, Italy; CNR Institute of Neuroscience, University of Padova, Viale G. Colombo 3, Padova 35131, Italy.
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11
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Carraretto L, Teardo E, Checchetto V, Finazzi G, Uozumi N, Szabo I. Ion Channels in Plant Bioenergetic Organelles, Chloroplasts and Mitochondria: From Molecular Identification to Function. MOLECULAR PLANT 2016; 9:371-395. [PMID: 26751960 DOI: 10.1016/j.molp.2015.12.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 11/22/2015] [Accepted: 12/01/2015] [Indexed: 06/05/2023]
Abstract
Recent technical advances in electrophysiological measurements, organelle-targeted fluorescence imaging, and organelle proteomics have pushed the research of ion transport a step forward in the case of the plant bioenergetic organelles, chloroplasts and mitochondria, leading to the molecular identification and functional characterization of several ion transport systems in recent years. Here we focus on channels that mediate relatively high-rate ion and water flux and summarize the current knowledge in this field, focusing on targeting mechanisms, proteomics, electrophysiology, and physiological function. In addition, since chloroplasts evolved from a cyanobacterial ancestor, we give an overview of the information available about cyanobacterial ion channels and discuss the evolutionary origin of chloroplast channels. The recent molecular identification of some of these ion channels allowed their physiological functions to be studied using genetically modified Arabidopsis plants and cyanobacteria. The view is emerging that alteration of chloroplast and mitochondrial ion homeostasis leads to organelle dysfunction, which in turn significantly affects the energy metabolism of the whole organism. Clear-cut identification of genes encoding for channels in these organelles, however, remains a major challenge in this rapidly developing field. Multiple strategies including bioinformatics, cell biology, electrophysiology, use of organelle-targeted ion-sensitive probes, genetics, and identification of signals eliciting specific ion fluxes across organelle membranes should provide a better understanding of the physiological role of organellar channels and their contribution to signaling pathways in plants in the future.
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Affiliation(s)
- Luca Carraretto
- Department of Biology, University of Padova, Padova 35121, Italy
| | - Enrico Teardo
- Department of Biology, University of Padova, Padova 35121, Italy; CNR Institute of Neuroscience, University of Padova, Padova 35121, Italy
| | | | - Giovanni Finazzi
- UMR 5168 Laboratoire de Physiologie Cellulaire Végétale (LPCV) CNRS/ UJF / INRA / CEA, Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), CEA Grenoble, 38054 Grenoble, France.
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan.
| | - Ildiko Szabo
- Department of Biology, University of Padova, Padova 35121, Italy; CNR Institute of Neuroscience, University of Padova, Padova 35121, Italy.
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12
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The Roles of Mitochondrial Cation Channels Under Physiological Conditions and in Cancer. Handb Exp Pharmacol 2016; 240:47-69. [PMID: 27995386 DOI: 10.1007/164_2016_92] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Bioenergetics has become central to our understanding of pathological mechanisms as well as the development of new therapeutic strategies and as a tool for gauging disease progression in neurodegeneration, diabetes, cancer, and cardiovascular disease. The view is emerging that inner mitochondrial membrane (IMM) cation channels have a profound effect on mitochondrial function and, consequently, on the metabolic state and survival of the whole cell. Since disruption of the sustained integrity of mitochondria is strongly linked to human disease, pharmacological intervention offers a new perspective concerning neurodegenerative and cardiovascular diseases as well as cancer. This review summarizes our current knowledge regarding IMM cation channels and their roles under physiological conditions as well as in cancer, with special emphasis on potassium channels and the mammalian mitochondrial calcium uniporter.
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13
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Xu H, Martinoia E, Szabo I. Organellar channels and transporters. Cell Calcium 2015; 58:1-10. [PMID: 25795199 DOI: 10.1016/j.ceca.2015.02.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 02/20/2015] [Indexed: 12/22/2022]
Abstract
Decades of intensive research have led to the discovery of most plasma membrane ion channels and transporters and the characterization of their physiological functions. In contrast, although over 80% of transport processes occur inside the cells, the ion flux mechanisms across intracellular membranes (the endoplasmic reticulum, Golgi apparatus, endosomes, lysosomes, mitochondria, chloroplasts, and vacuoles) are difficult to investigate and remain poorly understood. Recent technical advances in super-resolution microscopy, organellar electrophysiology, organelle-targeted fluorescence imaging, and organelle proteomics have pushed a large step forward in the research of intracellular ion transport. Many new organellar channels are molecularly identified and electrophysiologically characterized. Additionally, molecular identification of many of these ion channels/transporters has made it possible to study their physiological functions by genetic and pharmacological means. For example, organellar channels have been shown to regulate important cellular processes such as programmed cell death and photosynthesis, and are involved in many different pathologies. This special issue (SI) on organellar channels and transporters aims to provide a forum to discuss the recent advances and to define the standard and open questions in this exciting and rapidly developing field. Along this line, a new Gordon Research Conference dedicated to the multidisciplinary study of intracellular membrane transport proteins will be launched this coming summer.
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Affiliation(s)
- Haoxing Xu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 3089 Natural Science Building (Kraus), 830 North University Avenue, Ann Arbor, MI 48109-1048, USA.
| | - Enrico Martinoia
- Institute of Plant Biology, University of Zürich, Zollikerstr. 107, CH-8008 Zürich, Switzerland.
| | - Ildiko Szabo
- Department of Biology, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy; CNR Neuroscience Institute, Viale G. Colombo 3, 35121 Padova, Italy.
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