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Lewandowska J, Kalenik B, Wrzosek A, Szewczyk A. Redox Regulation of Mitochondrial Potassium Channels Activity. Antioxidants (Basel) 2024; 13:434. [PMID: 38671882 PMCID: PMC11047711 DOI: 10.3390/antiox13040434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 03/29/2024] [Accepted: 03/30/2024] [Indexed: 04/28/2024] Open
Abstract
Redox reactions exert a profound influence on numerous cellular functions with mitochondria playing a central role in orchestrating these processes. This pivotal involvement arises from three primary factors: (1) the synthesis of reactive oxygen species (ROS) by mitochondria, (2) the presence of a substantial array of redox enzymes such as respiratory chain, and (3) the responsiveness of mitochondria to the cellular redox state. Within the inner mitochondrial membrane, a group of potassium channels, including ATP-regulated, large conductance calcium-activated, and voltage-regulated channels, is present. These channels play a crucial role in conditions such as cytoprotection, ischemia/reperfusion injury, and inflammation. Notably, the activity of mitochondrial potassium channels is intricately governed by redox reactions. Furthermore, the regulatory influence extends to other proteins, such as kinases, which undergo redox modifications. This review aims to offer a comprehensive exploration of the modulation of mitochondrial potassium channels through diverse redox reactions with a specific focus on the involvement of ROS.
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Affiliation(s)
| | | | | | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (J.L.); (B.K.); (A.W.)
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2
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Chapa-Dubocq XR, Rodríguez-Graciani KM, Escobales N, Javadov S. Mitochondrial Volume Regulation and Swelling Mechanisms in Cardiomyocytes. Antioxidants (Basel) 2023; 12:1517. [PMID: 37627512 PMCID: PMC10451443 DOI: 10.3390/antiox12081517] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 07/24/2023] [Accepted: 07/26/2023] [Indexed: 08/27/2023] Open
Abstract
Mitochondrion, known as the "powerhouse" of the cell, regulates ion homeostasis, redox state, cell proliferation and differentiation, and lipid synthesis. The inner mitochondrial membrane (IMM) controls mitochondrial metabolism and function. It possesses high levels of proteins that account for ~70% of the membrane mass and are involved in the electron transport chain, oxidative phosphorylation, energy transfer, and ion transport, among others. The mitochondrial matrix volume plays a crucial role in IMM remodeling. Several ion transport mechanisms, particularly K+ and Ca2+, regulate matrix volume. Small increases in matrix volume through IMM alterations can activate mitochondrial respiration, whereas excessive swelling can impair the IMM topology and initiates mitochondria-mediated cell death. The opening of mitochondrial permeability transition pores, the well-characterized phenomenon with unknown molecular identity, in low- and high-conductance modes are involved in physiological and pathological increases of matrix volume. Despite extensive studies, the precise mechanisms underlying changes in matrix volume and IMM structural remodeling in response to energy and oxidative stressors remain unknown. This review summarizes and discusses previous studies on the mechanisms involved in regulating mitochondrial matrix volume, IMM remodeling, and the crosstalk between these processes.
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Affiliation(s)
| | | | | | - Sabzali Javadov
- Department of Physiology, University of Puerto Rico School of Medicine, San Juan, PR 00936-5067, USA; (X.R.C.-D.); (K.M.R.-G.); (N.E.)
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Liu T, Li T, Xu D, Wang Y, Zhou Y, Wan J, Huang CLH, Tan X. Small-conductance calcium-activated potassium channels in the heart: expression, regulation and pathological implications. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220171. [PMID: 37122223 PMCID: PMC10150224 DOI: 10.1098/rstb.2022.0171] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 12/25/2022] [Indexed: 05/02/2023] Open
Abstract
Ca2+-activated K+ channels are critical to cellular Ca2+ homeostasis and excitability; they couple intracellular Ca2+ and membrane voltage change. Of these, the small, 4-14 pS, conductance SK channels include three, KCNN1-3 encoded, SK1/KCa2.1, SK2/KCa2.2 and SK3/KCa2.3, channel subtypes with characteristic, EC50 ∼ 10 nM, 40 pM, 1 nM, apamin sensitivities. All SK channels, particularly SK2 channels, are expressed in atrial, ventricular and conducting system cardiomyocytes. Pharmacological and genetic modification results have suggested that SK channel block or knockout prolonged action potential durations (APDs) and effective refractory periods (ERPs) particularly in atrial, but also in ventricular, and sinoatrial, atrioventricular node and Purkinje myocytes, correspondingly affect arrhythmic tendency. Additionally, mitochondrial SK channels may decrease mitochondrial Ca2+ overload and reactive oxygen species generation. SK channels show low voltage but marked Ca2+ dependences (EC50 ∼ 300-500 nM) reflecting their α-subunit calmodulin (CaM) binding domains, through which they may be activated by voltage-gated or ryanodine-receptor Ca2+ channel activity. SK function also depends upon complex trafficking and expression processes and associations with other ion channels or subunits from different SK subtypes. Atrial and ventricular clinical arrhythmogenesis may follow both increased or decreased SK expression through decreased or increased APD correspondingly accelerating and stabilizing re-entrant rotors or increasing incidences of triggered activity. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.
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Affiliation(s)
- Ting Liu
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, People's Republic of China
| | - Tao Li
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, People's Republic of China
- Department of Cardiology, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, People's Republic of China
| | - Dandi Xu
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, People's Republic of China
| | - Yan Wang
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, People's Republic of China
| | - Yafei Zhou
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, People's Republic of China
| | - Juyi Wan
- Department of Cardiovascular Surgery, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, People's Republic of China
| | - Christopher L.-H. Huang
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, People's Republic of China
- Physiological Laboratory and Department of Biochemistry, University of Cambridge, Cambridge CB2 3EG, UK
| | - Xiaoqiu Tan
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, People's Republic of China
- Department of Cardiology, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, People's Republic of China
- Department of Physiology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan 646000, People's Republic of China
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4
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Li K, Jiang Y, Zeng Y, Zhou Y. Advances in Ion Channel, Non-Desmosomal Variants and Autophagic Mechanisms Implicated in Arrhythmogenic Cardiomyopathy. Curr Issues Mol Biol 2023; 45:2186-2200. [PMID: 36975511 PMCID: PMC10047275 DOI: 10.3390/cimb45030141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 02/28/2023] [Accepted: 03/01/2023] [Indexed: 03/11/2023] Open
Abstract
Arrhythmogenic cardiomyopathy (ACM) is a heterogeneous disorder characterized by the replacement of cardiac myocytes with fibro-fatty tissues, leading to abnormal excitation-contraction (EC) coupling and a range of malignant events, such as ventricular tachycardia (VT), sudden cardiac death/arrest (SCD/A) and heart failure (HF). The concept of ACM has recently been ex-tended to include right ventricular cardiomyopathy (ARVC), left ventricular cardiomyopathy (ALVC) and biventricular cardiomyopathy. ARVC is generally seen as the most common type of ACM. The pathogenesis of ACM involves mutation variants in desmosomal or non-desmosomal gene loci, as well as various external factors, such as intense exercise, stress and infections. Ion channel alterations, autophagy and non-desmosomal variants are also important components in the development of ACM. As clinical practice enters the era of precision therapy, it is important to review recent studies on these topics to better diagnose and treat the molecular phase of ACM.
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Affiliation(s)
- Kexin Li
- Department of Cardiology, Dushu Lake Hospital Affiliated to Soochow University, Suzhou 215000, China
- Institution for Hypertension of Soochow University, Suzhou 215000, China
| | - Yufeng Jiang
- Department of Cardiology, Dushu Lake Hospital Affiliated to Soochow University, Suzhou 215000, China
- Institution for Hypertension of Soochow University, Suzhou 215000, China
| | - Yiyao Zeng
- Department of Cardiology, Dushu Lake Hospital Affiliated to Soochow University, Suzhou 215000, China
- Institution for Hypertension of Soochow University, Suzhou 215000, China
| | - Yafeng Zhou
- Department of Cardiology, Dushu Lake Hospital Affiliated to Soochow University, Suzhou 215000, China
- Institution for Hypertension of Soochow University, Suzhou 215000, China
- Correspondence: ; Tel.: +86-512-65955026
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Kim J, Zimmerman MA, Shin WY, Boettcher BT, Lee JS, Park JI, Ali M, Yang M, Mishra J, Hagen CE, McGraw JE, Mathison A, Woehlck HJ, Lomberk G, Camara AKS, Urrutia RA, Stowe DF, Hong JC. Effects of Subnormothermic Regulated Hepatic Reperfusion on Mitochondrial and Transcriptomic Profiles in a Porcine Model. Ann Surg 2023; 277:e366-e375. [PMID: 34387201 PMCID: PMC8840998 DOI: 10.1097/sla.0000000000005156] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE We sought to investigate the biological effects of pre-reperfusion treatments of the liver after warm and cold ischemic injuries in a porcine donation after circulatory death model. SUMMARY OF BACKGROUND DATA Donation after circulatory death represents a severe form of liver ischemia and reperfusion injury that has a profound impact on graft function after liver transplantation. METHODS Twenty donor pig livers underwent 60 minutes of in situ warm ischemia after circulatory arrest and 120 minutes of cold static preservation prior to simulated transplantation using an ex vivo perfusion machine. Four reperfusion treatments were compared: Control-Normothermic (N), Control- Subnormothermic (S), regulated hepatic reperfusion (RHR)-N, and RHR-S (n = 5 each). The biochemical, metabolic, and transcriptomic profiles, as well as mitochondrial function were analyzed. RESULTS Compared to the other groups, RHR-S treated group showed significantly lower post-reperfusion aspartate aminotransferase levels in the reperfusion effluent and histologic findings of hepatocyte viability and lesser degree of congestion and necrosis. RHR-S resulted in a significantly higher mitochondrial respiratory control index and calcium retention capacity. Transcriptomic profile analysis showed that treatment with RHR-S activated cell survival and viability, cellular homeostasis as well as other biological functions involved in tissue repair such as cytoskeleton or cytoplasm organization, cell migration, transcription, and microtubule dynamics. Furthermore, RHR-S inhibited organismal death, morbidity and mortality, necrosis, and apoptosis. CONCLUSION Subnormothermic RHR mitigates IRI and preserves hepatic mitochondrial function after warm and cold hepatic ischemia. This organ resuscitative therapy may also trigger the activation of protective genes against IRI. Sub- normothermic RHR has potential applicability to clinical liver transplantation.
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Affiliation(s)
- Joohyun Kim
- Division of Transplant Surgery, Department of Surgery, Medical College of Wisconsin, Milwaukee WI
- Transplant Center, Froedtert & the Medical College of Wisconsin, and Children's Wisconsin, Milwaukee, WI
| | - Michael A Zimmerman
- Division of Transplant Surgery, Department of Surgery, Medical College of Wisconsin, Milwaukee WI
- Transplant Center, Froedtert & the Medical College of Wisconsin, and Children's Wisconsin, Milwaukee, WI
| | - Woo Young Shin
- Department of Surgery, inha University School of Medicine, incheon, South Korea
| | - Brent T Boettcher
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI
| | - Ju-Seog Lee
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Jong-In Park
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI
| | - Muhammed Ali
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI
| | - Meiying Yang
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI
| | - Jyotsna Mishra
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI
| | | | - Joseph E McGraw
- Department of Pharmacology, Concordia University, Mequon, WI
| | - Angela Mathison
- Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI; and
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee WI
| | - Harvey J Woehlck
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI
| | - Gwen Lomberk
- Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI; and
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee WI
| | - Amadou K S Camara
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI
| | - Raul A Urrutia
- Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI; and
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee WI
| | - David F Stowe
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI
| | - Johnny C Hong
- Division of Transplant Surgery, Department of Surgery, Medical College of Wisconsin, Milwaukee WI
- Transplant Center, Froedtert & the Medical College of Wisconsin, and Children's Wisconsin, Milwaukee, WI
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Butler AS, Hancox JC, Marrion NV. Preferential formation of human heteromeric SK2:SK3 channels limits homomeric SK channel assembly and function. J Biol Chem 2022; 299:102783. [PMID: 36502918 PMCID: PMC9841042 DOI: 10.1016/j.jbc.2022.102783] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 11/29/2022] [Accepted: 12/04/2022] [Indexed: 12/13/2022] Open
Abstract
Three isoforms of small conductance, calcium-activated potassium (SK) channel subunits have been identified (SK1-3) that exhibit a broad and overlapping tissue distribution. SK channels have been implicated in several disease states including hypertension and atrial fibrillation, but therapeutic targeting of SK channels is hampered by a lack of subtype-selective inhibitors. This is further complicated by studies showing that SK1 and SK2 preferentially form heteromeric channels during co-expression, likely limiting the function of homomeric channels in vivo. Here, we utilized a simplified expression system to investigate functional current produced when human (h) SK2 and hSK3 subunits are co-expressed. When expressed alone, hSK3 subunits were more clearly expressed on the cell surface than hSK2 subunits. hSK3 surface expression was reduced by co-transfection with hSK2. Whole-cell recording showed homomeric hSK3 currents were larger than homomeric hSK2 currents or heteromeric hSK2:hSK3 currents. The smaller amplitude of hSK2:hSK3-mediated current when compared with homomeric hSK3-mediated current suggests hSK2 subunits regulate surface expression of heteromers. Co-expression of hSK2 and hSK3 subunits produced a current that arose from a single population of heteromeric channels as exhibited by an intermediate sensitivity to the inhibitors apamin and UCL1684. Co-expression of the apamin-sensitive hSK2 subunit and a mutant, apamin-insensitive hSK3 subunit [hSK3(H485N)], produced an apamin-sensitive current. Concentration-inhibition relationships were best fit by a monophasic Hill equation, confirming preferential formation of heteromers. These data show that co-expressed hSK2 and hSK3 preferentially form heteromeric channels and suggest that the hSK2 subunit acts as a chaperone, limiting membrane expression of hSK2:hSK3 heteromeric channels.
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Affiliation(s)
- Andrew S Butler
- School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, University of Bristol, University Walk, Bristol, United Kingdom
| | - Jules C Hancox
- School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, University of Bristol, University Walk, Bristol, United Kingdom.
| | - Neil V Marrion
- School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, University of Bristol, University Walk, Bristol, United Kingdom.
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7
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Malas KM, Lambert DS, Heisner JS, Camara AKS, Stowe DF. Time and charge/pH-dependent activation of K + channel-mediated K + influx and K +/H + exchange in guinea pig heart isolated mitochondria; role in bioenergetic stability. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148908. [PMID: 35961396 DOI: 10.1016/j.bbabio.2022.148908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 07/17/2022] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
Mitochondria play an important role not only in producing energy for the cell but also for regulating mitochondrial and cell function depending on the cell's needs and environment. Uptake of cations, anions, and substrates requires a stable, polarized transmembrane charge potential (ΔΨm). Chemiosmosis requires ion exchangers to remove Na+, K+, Ca2+, PO43-, and other charged species that enter mitochondria. Knowledge of the kinetics of mitochondrial (m) cation channels and exchangers is important in understanding their roles in regulating mitochondrial chemiosmosis and bioenergetics. The influx/efflux of K+, the most abundant mitochondrial cation, alters mitochondrial volume and shape by bringing in anions and H2O by osmosis. The effects of K+ uptake through ligand-specific mK+ channels stimulated/inhibited by agonists/antagonists on mitochondrial volume (swelling/contraction) are well known. However, a more important role for K+ influx is likely its effects on H+ cycling and bioenergetics facilitated by mitochondrial (m) K+/H+ exchange (mKHE), though the kinetics and consequences of K+ efflux by KHE are not well described. We hypothesized that a major role of K+ influx/efflux is stimulation of respiration via the influx of H+ by KHE. We proposed to modulate KHE activity by energizing guinea pig heart isolated mitochondria and by altering the mK+ cycle to capture changes in mitochondrial volume, pHm, ΔΨm, and respiration that would reflect a role for H+ influx via KHE to regulate bioenergetics. To test this, mitochondria were suspended in a 150 mM K+ buffer at pH 6.9, or in a 140 mM Cs+ buffer at pH 7.6 or 6.9 with added 10 mM K+, minimal Ca2+ and free of Na+. O2 content was measured by a Clark electrode, and pHm, ΔΨm, and volume, were measured by fluorescence spectrophotometry and light-scattering. Adding pyruvic acid (PA) alone caused increases in volume and respiration and a rapid decrease in the transmembrane pH gradient (ΔpHm = pHin-pHext) at pHext 6.9> > 7.6, so that ΔΨm was charged and maintained. BKCa agonist NS1619 and antagonist paxilline modified these effects, and KHE inhibitor quinine and K+ ionophore valinomycin depolarized ΔΨm. We postulate that K+ efflux-induced H+ influx via KHE causes an inward H+ leak that stimulates respiration, but at buffer pH 6.9 also utilizes the energy of ΔpHm, the smaller component of the overall proton motive force, ΔμH+. Thus ΔpHm establishes and maintains the ΔΨm required for utilization of substrates, entry of all cations, and for oxidative phosphorylation. Thus, K+ influx/efflux appears to play a pivotal role in regulating energetics while maintaining mitochondrial ionic balance and volume homeostasis.
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Affiliation(s)
- Kareem M Malas
- Department of Anesthesiology, Research Division, Medical College of Wisconsin, Milwaukee, WI, USA
| | - David S Lambert
- Department of Anesthesiology, Research Division, Medical College of Wisconsin, Milwaukee, WI, USA
| | - James S Heisner
- Department of Anesthesiology, Research Division, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Amadou K S Camara
- Department of Anesthesiology, Research Division, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA; Cancer Center, Medical College of Wisconsin, Milwaukee, WI, USA
| | - David F Stowe
- Department of Anesthesiology, Research Division, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA; Departments of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, WI, USA; Zablocki Veterans Administration, Research Service, Milwaukee, WI, USA.
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Fuest S, Post C, Balbach ST, Jabar S, Neumann I, Schimmelpfennig S, Sargin S, Nass E, Budde T, Kailayangiri S, Altvater B, Ranft A, Hartmann W, Dirksen U, Rössig C, Schwab A, Pethő Z. Relevance of Abnormal KCNN1 Expression and Osmotic Hypersensitivity in Ewing Sarcoma. Cancers (Basel) 2022; 14:cancers14194819. [PMID: 36230742 PMCID: PMC9564116 DOI: 10.3390/cancers14194819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/27/2022] [Accepted: 09/29/2022] [Indexed: 12/02/2022] Open
Abstract
Simple Summary The main oncogene in Ewing sarcoma directly drives a high expression of a previously unknown variant KCNN1 (encoding the KCa2.1 channel) that we also verified in samples from >200 patients. Yet, we found that the channel is not functional and does not modulate Ewing sarcoma cell behavior. We could explain this lack of functional impact by the surprising absence of any KCa2.1-carried K+ current in Ewing sarcoma cells. However, we show in a proof-of-principle study that the essential lack of a K+ conductance can be exploited by applying hypoosmotic stress and effectively and selectively killing the Ewing sarcoma cells. Abstract Ewing sarcoma (EwS) is a rare and highly malignant bone tumor occurring mainly in childhood and adolescence. Physiologically, the bone is a central hub for Ca2+ homeostasis, which is severely disturbed by osteolytic processes in EwS. Therefore, we aimed to investigate how ion transport proteins involved in Ca2+ homeostasis affect EwS pathophysiology. We characterized the expression of 22 candidate genes of Ca2+-permeable or Ca2+-regulated ion channels in three EwS cell lines and found the Ca2+-activated K+ channel KCa2.1 (KCNN1) to be exceptionally highly expressed. We revealed that KCNN1 expression is directly regulated by the disease-driving oncoprotein EWSR1-FL1. Due to its consistent overexpression in EwS, KCNN1 mRNA could be a prognostic marker in EwS. In a large cohort of EwS patients, however, KCNN1 mRNA quantity does not correlate with clinical parameters. Several functional studies including patch clamp electrophysiology revealed no evidence for KCa2.1 function in EwS cells. Thus, elevated KCNN1 expression is not translated to KCa2.1 channel activity in EwS cells. However, we found that the low K+ conductance of EwS cells renders them susceptible to hypoosmotic solutions. The absence of a relevant K+ conductance in EwS thereby provides an opportunity for hypoosmotic therapy that can be exploited during tumor surgery.
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Affiliation(s)
- Sebastian Fuest
- Institute of Physiology II, University Münster, 48149 Münster, Germany
| | - Christoph Post
- Institute of Physiology II, University Münster, 48149 Münster, Germany
| | - Sebastian T. Balbach
- Department of Pediatric Hematology and Oncology, University Children’s Hospital Münster, 48149 Münster, Germany
| | - Susanne Jabar
- Pediatrics III, University Hospital Essen, 45147 Essen, Germany
| | - Ilka Neumann
- Institute of Physiology II, University Münster, 48149 Münster, Germany
| | | | - Sarah Sargin
- Institute of Physiology II, University Münster, 48149 Münster, Germany
| | - Elke Nass
- Institute of Physiology I, University Münster, 48149 Münster, Germany
| | - Thomas Budde
- Institute of Physiology I, University Münster, 48149 Münster, Germany
| | - Sareetha Kailayangiri
- Department of Pediatric Hematology and Oncology, University Children’s Hospital Münster, 48149 Münster, Germany
| | - Bianca Altvater
- Department of Pediatric Hematology and Oncology, University Children’s Hospital Münster, 48149 Münster, Germany
| | - Andreas Ranft
- Pediatrics III, University Hospital Essen, 45147 Essen, Germany
| | - Wolfgang Hartmann
- Division of Translational Pathology, Gerhard-Domagk-Institute of Pathology, University Münster, 48149 Münster, Germany
| | - Uta Dirksen
- Pediatrics III, University Hospital Essen, 45147 Essen, Germany
| | - Claudia Rössig
- Department of Pediatric Hematology and Oncology, University Children’s Hospital Münster, 48149 Münster, Germany
| | - Albrecht Schwab
- Institute of Physiology II, University Münster, 48149 Münster, Germany
| | - Zoltán Pethő
- Institute of Physiology II, University Münster, 48149 Münster, Germany
- Correspondence:
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9
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Droogers WJ, Willems J, MacGillavry HD, de Jong APH. Duplex Labeling and Manipulation of Neuronal Proteins Using Sequential CRISPR/Cas9 Gene Editing. eNeuro 2022; 9:ENEURO.0056-22.2022. [PMID: 35851300 PMCID: PMC9333357 DOI: 10.1523/eneuro.0056-22.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 04/20/2022] [Accepted: 04/28/2022] [Indexed: 11/21/2022] Open
Abstract
CRISPR/Cas9-mediated knock-in methods enable the labeling of individual endogenous proteins to faithfully determine their spatiotemporal distribution in cells. However, reliable multiplexing of knock-in events in neurons remains challenging because of cross talk between editing events. To overcome this, we developed conditional activation of knock-in expression (CAKE), allowing efficient, flexible, and accurate multiplex genome editing in rat neurons. To diminish cross talk, CAKE is based on sequential, recombinase-driven guide RNA (gRNA) expression to control the timing of genomic integration of each donor sequence. We show that CAKE is broadly applicable to co-label various endogenous proteins, including cytoskeletal proteins, synaptic scaffolds, ion channels and neurotransmitter receptor subunits. To take full advantage of CAKE, we resolved the nanoscale co-distribution of endogenous synaptic proteins using super-resolution microscopy, demonstrating that their co-organization depends on synapse size. Finally, we introduced inducible dimerization modules, providing acute control over synaptic receptor dynamics in living neurons. These experiments highlight the potential of CAKE to reveal new biological insight. Altogether, CAKE is a versatile method for multiplex protein labeling that enables the detection, localization, and manipulation of endogenous proteins in neurons.Significance StatementAccurate localization and manipulation of endogenous proteins is essential to unravel neuronal function. While labeling of individual proteins is achievable with existing gene editing techniques, methods to label multiple proteins in neurons are limiting. We introduce a new CRISPR/Cas9 strategy, CAKE, achieving faithful duplex protein labeling using sequential editing of genes. We use CAKE to visualize the co-localization of essential neuronal proteins, including cytoskeleton components, ion channels and synaptic scaffolds. Using super-resolution microscopy, we demonstrate that the co-organization of synaptic scaffolds and neurotransmitter receptors scales with synapse size. Finally, we acutely modulate the dynamics of synaptic receptors using labeling with inducible dimerization domains. Thus, CAKE mediates accurate duplex endogenous protein labeling and manipulation to address biological questions in neurons.
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Affiliation(s)
- Wouter J Droogers
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Jelmer Willems
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Harold D MacGillavry
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Arthur P H de Jong
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
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10
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Hypothermia Prevents Cardiac Dysfunction during Acute Ischemia Reperfusion by Maintaining Mitochondrial Bioenergetics and by Promoting Hexokinase II Binding to Mitochondria. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:4476448. [PMID: 35873800 PMCID: PMC9301761 DOI: 10.1155/2022/4476448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 03/04/2022] [Accepted: 06/14/2022] [Indexed: 11/18/2022]
Abstract
Background Hypothermia (H), cardioplegia (CP), and both combined (HCP) are known to be protective against myocardial ischemia reperfusion (IR) injury. Mitochondria have molecular signaling mechanisms that are associated with both cell survival and cell death. In this study, we investigated the dynamic changes in proapoptotic and prosurvival signaling pathways mediating H, CP, or HCP-induced protection of mitochondrial function after acute myocardial IR injury. Methods Rats were divided into five groups. Each group consists of 3 subgroups based on a specific reperfusion time (5, 20, or 60 min) after a 25-min global ischemia. The time control (TC) groups were not subjected to IR but were perfused with 37 °C Krebs-Ringer's (KR) buffer, containing 4.5 mM K+, in a specific perfusion protocol that corresponded with the duration of each IR protocol. The IR group (control) was perfused for 20 min with KR, followed by 25-min global ischemia, and then KR reperfusion for 5, 20, or 60 min. The treatment groups were exposed to 17 °C H, 37 °C CP (16 mM K+), or HCP (17 °C + CP) for 5 min before ischemia and for 2 min on reperfusion before switching to 37 °C KR perfusion for the remainder of each of the reperfusion times. Cardiac function and mitochondrial redox state (NADH/FAD) were monitored online in the ex vivo hearts before, during, and after ischemia. Mitochondria were isolated at the end of each specified reperfusion time, and changes in O2 consumption, membrane potential (ΔΨm), and Ca2+ retention capacity (CRC) were assessed using complex I and complex II substrates. In another set of hearts, mitochondrial and cytosolic fractions were isolated after a specified reperfusion time to conduct western blot assays to determine hexokinase II (HKII) and Bax binding/translocation to mitochondria, cytosolic pAkt levels, and cytochrome c (Cyto-c) release into the cytosol. Results H and HCP were more protective of mitochondrial integrity and, concomitantly, cardiac function than CP alone; H and HCP improved post-ischemic cardiac function by (1) maintaining mitochondrial bioenergetics, (2) maintaining HKII binding to mitochondria with an increase in pAkt levels, (3) increasing CRC, and (4) decreasing Cyto-c release during reperfusion. Bax translocation/binding to mitochondria was unaffected by any treatment, regardless of cardiac functional recovery. Conclusions Hypothermia preserved mitochondrial function and cardiac function, in part, by maintaining mitochondrial bioenergetics, by retaining HKII binding to mitochondria via upstream pAkt, and by reducing Cyto-c release independently of Bax binding to mitochondria.
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Methods of Measuring Mitochondrial Potassium Channels: A Critical Assessment. Int J Mol Sci 2022; 23:ijms23031210. [PMID: 35163132 PMCID: PMC8835872 DOI: 10.3390/ijms23031210] [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: 11/17/2021] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 12/22/2022] Open
Abstract
In this paper, the techniques used to study the function of mitochondrial potassium channels are critically reviewed. The majority of these techniques have been known for many years as a result of research on plasma membrane ion channels. Hence, in this review, we focus on the critical evaluation of techniques used in the studies of mitochondrial potassium channels, describing their advantages and limitations. Functional analysis of mitochondrial potassium channels in comparison to that of plasmalemmal channels presents additional experimental challenges. The reliability of functional studies of mitochondrial potassium channels is often affected by the need to isolate mitochondria and by functional properties of mitochondria such as respiration, metabolic activity, swelling capacity, or high electrical potential. Three types of techniques are critically evaluated: electrophysiological techniques, potassium flux measurements, and biochemical techniques related to potassium flux measurements. Finally, new possible approaches to the study of the function of mitochondrial potassium channels are presented. We hope that this review will assist researchers in selecting reliable methods for studying, e.g., the effects of drugs on mitochondrial potassium channel function. Additionally, this review should aid in the critical evaluation of the results reported in various articles on mitochondrial potassium channels.
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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] [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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Checchetto V, Leanza L, De Stefani D, Rizzuto R, Gulbins E, Szabo I. Mitochondrial K + channels and their implications for disease mechanisms. Pharmacol Ther 2021; 227:107874. [PMID: 33930454 DOI: 10.1016/j.pharmthera.2021.107874] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 04/12/2021] [Indexed: 02/06/2023]
Abstract
The field of mitochondrial ion channels underwent a rapid development during the last decade, thanks to the molecular identification of some of the nuclear-encoded organelle channels and to advances in strategies allowing specific pharmacological targeting of these proteins. Thereby, genetic tools and specific drugs aided definition of the relevance of several mitochondrial channels both in physiological as well as pathological conditions. Unfortunately, in the case of mitochondrial K+ channels, efforts of genetic manipulation provided only limited results, due to their dual localization to mitochondria and to plasma membrane in most cases. Although the impact of mitochondrial K+ channels on human diseases is still far from being genuinely understood, pre-clinical data strongly argue for their substantial role in the context of several pathologies, including cardiovascular and neurodegenerative diseases as well as cancer. Importantly, these channels are druggable targets, and their in-depth investigation could thus pave the way to the development of innovative small molecules with huge therapeutic potential. In the present review we summarize the available experimental evidence that mechanistically link mitochondrial potassium channels to the above pathologies and underline the possibility of exploiting them for therapy.
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Affiliation(s)
| | - Luigi Leanza
- Department of Biology, University of Padova, Italy
| | | | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, Italy
| | - Erich Gulbins
- Department of Molecular Biology, University of Duisburg-Essen, Germany
| | - Ildiko Szabo
- Department of Biology, University of Padova, Italy; CNR Institute of Neurosciences, Italy.
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Zhang XD, Thai PN, Lieu DK, Chiamvimonvat N. Cardiac small-conductance calcium-activated potassium channels in health and disease. Pflugers Arch 2021; 473:477-489. [PMID: 33624131 PMCID: PMC7940285 DOI: 10.1007/s00424-021-02535-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 12/22/2022]
Abstract
Small-conductance Ca2+-activated K+ (SK, KCa2) channels are encoded by KCNN genes, including KCNN1, 2, and 3. The channels play critical roles in the regulation of cardiac excitability and are gated solely by beat-to-beat changes in intracellular Ca2+. The family of SK channels consists of three members with differential sensitivity to apamin. All three isoforms are expressed in human hearts. Studies over the past two decades have provided evidence to substantiate the pivotal roles of SK channels, not only in healthy heart but also with diseases including atrial fibrillation (AF), ventricular arrhythmia, and heart failure (HF). SK channels are prominently expressed in atrial myocytes and pacemaking cells, compared to ventricular cells. However, the channels are significantly upregulated in ventricular myocytes in HF and pulmonary veins in AF models. Interests in cardiac SK channels are further fueled by recent studies suggesting the possible roles of SK channels in human AF. Therefore, SK channel may represent a novel therapeutic target for atrial arrhythmias. Furthermore, SK channel function is significantly altered by human calmodulin (CaM) mutations, linked to life-threatening arrhythmia syndromes. The current review will summarize recent progress in our understanding of cardiac SK channels and the roles of SK channels in the heart in health and disease.
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Affiliation(s)
- Xiao-Dong Zhang
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, One Shields Avenue, GBSF 6315, Davis, CA, 95616, USA.
- Department of Veterans Affairs, Northern California Health Care System, 10535 Hospital Way, Mather, CA, 95655, USA.
| | - Phung N Thai
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, One Shields Avenue, GBSF 6315, Davis, CA, 95616, USA
- Department of Veterans Affairs, Northern California Health Care System, 10535 Hospital Way, Mather, CA, 95655, USA
| | - Deborah K Lieu
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, One Shields Avenue, GBSF 6315, Davis, CA, 95616, USA
| | - Nipavan Chiamvimonvat
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, One Shields Avenue, GBSF 6315, Davis, CA, 95616, USA.
- Department of Veterans Affairs, Northern California Health Care System, 10535 Hospital Way, Mather, CA, 95655, USA.
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, 95616, USA.
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Weisbrod D. Small and Intermediate Calcium Activated Potassium Channels in the Heart: Role and Strategies in the Treatment of Cardiovascular Diseases. Front Physiol 2020; 11:590534. [PMID: 33329039 PMCID: PMC7719780 DOI: 10.3389/fphys.2020.590534] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Accepted: 10/02/2020] [Indexed: 12/11/2022] Open
Abstract
Calcium-activated potassium channels are a heterogeneous family of channels that, despite their different biophysical characteristics, structures, and pharmacological signatures, play a role of transducer between the ubiquitous intracellular calcium signaling and the electric variations of the membrane. Although this family of channels was extensively described in various excitable and non-excitable tissues, an increasing amount of evidences shows their functional role in the heart. This review aims to focus on the physiological role and the contribution of the small and intermediate calcium-activated potassium channels in cardiac pathologies.
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16
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Development of pyrene-based fluorescent ether lipid as inhibitor of SK3 ion channels. Eur J Med Chem 2020; 209:112894. [PMID: 33049604 DOI: 10.1016/j.ejmech.2020.112894] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 09/04/2020] [Accepted: 09/24/2020] [Indexed: 01/11/2023]
Abstract
We report the synthesis of three bioactive pyrene-based fluorescent analogues of Ohmline which is the most efficient and selective inhibitor of SK3 ion channel. The interaction of these Ohmline-pyrene (OP1-3) with liposomes of different composition reveals that only OP2 and OP3 are readily integrated into liposomes. Fluorescence measurements indicate that, depending on their concentration, OP2 and OP3 exist either as monomer or as a mixture of monomer and excimers within the liposome bilayer. Among the three Ohmline Pyrene compounds (OP1-3) only OP2 is able to reduce SK3 currents and is the first efficient fluorescent modulator of SK3 channel as revealed by patch clamp measurements (- 71.3 ± 13.3% at 10 μM) and by its inhibition of SK3-dependent cancer cell migration at (-32.5% ± 4.8% at 1 μM). We also report the first fluorescence study on living breast cancer cells (MDA-MB-231) showing that OP2 is rapidly integrated in bio-membranes followed by cell internalization.
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17
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Gerdes HJ, Yang M, Heisner JS, Camara AKS, Stowe DF. Modulation of peroxynitrite produced via mitochondrial nitric oxide synthesis during Ca 2+ and succinate-induced oxidative stress in cardiac isolated mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148290. [PMID: 32828729 DOI: 10.1016/j.bbabio.2020.148290] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/23/2020] [Accepted: 07/29/2020] [Indexed: 01/09/2023]
Abstract
We hypothesized that NO• is generated in isolated cardiac mitochondria as the source for ONOO- production during oxidative stress. We monitored generation of ONOO- from guinea pig isolated cardiac mitochondria subjected to excess Ca2+ uptake before adding succinate and determined if ONOO- production was dependent on a nitric oxide synthase (NOS) located in cardiac mitochondria (mtNOS). Mitochondria were suspended in experimental buffer at pH 7.15, and treated with CaCl2 and then the complex II substrate Na-succinate, followed by menadione, a quinone redox cycler, to generate O2•-. L-tyrosine was added to the mitochondrial suspension where it is oxidized by ONOO- to form dityrosine (diTyr) in proportion to the ONOO- present. We found that exposing mitochondria to excess CaCl2 before succinate resulted in an increase in diTyr and amplex red fluorescence (H2O2) signals, indicating that mitochondrial oxidant stress, induced by elevated mtCa2+ and succinate, increased mitochondrial ONOO- production via NO• and O2•-. Changes in mitochondrial ONOO- production dependent on NOS were evidenced by using NOS inhibitors L-NAME/L-NNA, TEMPOL, a superoxide dismutase (SOD) mimetic, and PTIO, a potent global NO• scavenger. L-NAME and L-NNA decreased succinate and menadione-mediated ONOO- production, PTIO decreased production of ONOO-, and TEMPOL decreased ONOO- levels by converting more O2•- to H2O2. Electron microscopy showed immuno-gold labeled iNOS and nNOS in mitochondria isolated from cardiomyocytes and heart tissue. Western blots demonstrated iNOS and nNOS bands in total heart tissue, bands for both iNOS and nNOS in β-tubulin-free non-purified (crude) mitochondrial preparations, and a prominent iNOS band, but no nNOS band, in purified (Golgi and ER-free) mitochondria. Prior treatment of guinea pigs with lipopolysacharride (LPS) enhanced expression of iNOS in liver mitochondria but not in heart mitochondria. Our results indicate that release of ONOO- into the buffer is dependent both on O2•- released from mitochondria and NO• derived from a mtCa2+-inducible nNOS isoform, possibly attached to mitochondria, and a mtNOS isoform like iNOS that is non-inducible.
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Affiliation(s)
- Harrison J Gerdes
- Anesthesiology Research Division, Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Meiying Yang
- Anesthesiology Research Division, Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - James S Heisner
- Anesthesiology Research Division, Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Amadou K S Camara
- Anesthesiology Research Division, Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, USA; Cancer Center, Medical College of Wisconsin, Milwaukee, WI, USA
| | - David F Stowe
- Anesthesiology Research Division, Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA; Cancer Center, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Biomedical Engineering, Medical College of Wisconsin and Marquette University, Milwaukee, WI, USA; Research Service, Zablocki Veterans Affairs Medical Center, Milwaukee, WI, USA.
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18
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“Funny” channels in cardiac mitochondria modulate membrane potential and oxygen consumption. Biochem Biophys Res Commun 2020; 524:1030-1036. [DOI: 10.1016/j.bbrc.2020.02.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 02/05/2020] [Indexed: 11/20/2022]
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19
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Ragab AAY, Sitorus GDS, Brundel BBJJM, de Groot NMS. The Genetic Puzzle of Familial Atrial Fibrillation. Front Cardiovasc Med 2020; 7:14. [PMID: 32118049 PMCID: PMC7033574 DOI: 10.3389/fcvm.2020.00014] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 01/28/2020] [Indexed: 12/17/2022] Open
Abstract
Atrial fibrillation (AF) is the most common clinical tachyarrhythmia. In Europe, AF is expected to reach a prevalence of 18 million by 2060. This estimate will increase hospitalization for AF to 4 million and 120 million outpatient visits. Besides being an independent risk factor for mortality, AF is also associated with an increased risk of morbidities. Although there are many well-defined risk factors for developing AF, no identifiable risk factors or cardiac pathology is seen in up to 30% of the cases. The heritability of AF has been investigated in depth since the first report of familial atrial fibrillation (FAF) in 1936. Despite the limited value of animal models, the advances in molecular genetics enabled identification of many common and rare variants related to FAF. The importance of AF heritability originates from the high prevalence of lone AF and the lack of clear understanding of the underlying pathophysiology. A better understanding of FAF will facilitate early identification of people at high risk of developing FAF and subsequent development of more effective management options. In this review, we reviewed FAF epidemiological studies, identified common and rare variants, and discussed their clinical implications and contributions to developing new personalized therapeutic strategies.
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Affiliation(s)
- Ahmed A Y Ragab
- Department of Cardiology, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Gustaf D S Sitorus
- Department of Cardiology, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Bianca B J J M Brundel
- Department of Physiology, Institute for Cardiovascular Research, VU Medical Center, Amsterdam, Netherlands
| | - Natasja M S de Groot
- Department of Cardiology, Erasmus University Medical Center, Rotterdam, Netherlands
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20
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Sakamoto K, Kurokawa J. Involvement of sex hormonal regulation of K + channels in electrophysiological and contractile functions of muscle tissues. J Pharmacol Sci 2019; 139:259-265. [PMID: 30962088 DOI: 10.1016/j.jphs.2019.02.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 02/14/2019] [Accepted: 02/28/2019] [Indexed: 11/19/2022] Open
Abstract
Sex hormones, such as testosterone, progesterone, and 17β-estradiol, control various physiological functions. This review focuses on the sex hormonal regulation of K+ channels and the effects of such regulation on electrophysiological and contractile functions of muscles. In the cardiac tissue, testosterone and progesterone shorten action potential, and estrogen lengthens QT interval, a marker of increased risk of ventricular tachyarrhythmias. We have shown that testosterone and progesterone in physiological concentration activate KCNQ1 channels via membrane-delimited sex hormone receptor/eNOS pathways to shorten the action potential duration. Mitochondrial K+ channels are also involved in the protection of cardiac muscle. Testosterone and 17β-estradiol directly activate mitochondrial inner membrane K+ channels (Ca2+ activated K+ channel (KCa channel) and ATP-sensitive K+ channel (KATP channel)) that are involved in ischemic preconditioning and cardiac protection. During pregnancy, uterine blood flow increases to support fetal growth and development. It has been reported that 17β-estradiol directly activates large-conductance Ca2+-activated K+ channel (BKCa channel) attenuating arterial contraction. Furthermore, 17β-estradiol increases expression of BKCa channel β1 subunit which enhances BKCa channel activity by DNA demethylation. These findings are useful for understanding the mechanisms of sex or generation-dependent differences in the physiological and pathological functions of muscles, and the mechanisms of drug actions.
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Affiliation(s)
- Kazuho Sakamoto
- Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
| | - Junko Kurokawa
- Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
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21
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Yang M, Xu Y, Heisner JS, Sun J, Stowe DF, Kwok WM, Camara AKS. Peroxynitrite nitrates adenine nucleotide translocase and voltage-dependent anion channel 1 and alters their interactions and association with hexokinase II in mitochondria. Mitochondrion 2018; 46:380-392. [PMID: 30391711 DOI: 10.1016/j.mito.2018.10.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 09/26/2018] [Accepted: 10/22/2018] [Indexed: 12/17/2022]
Abstract
Cardiac ischemia and reperfusion (IR) injury induces excessive emission of deleterious reactive O2 and N2 species (ROS/RNS), including the non-radical oxidant peroxynitrite (ONOO-) that can cause mitochondria dysfunction and cell death. In this study, we explored whether IR injury in isolated hearts induces tyrosine nitration of adenine nucleotide translocase (ANT) and alters its interaction with the voltage-dependent anion channel 1 (VDAC1). We found that IR injury induced tyrosine nitration of ANT and that exposure of isolated cardiac mitochondria to ONOO- induced ANT tyrosine, Y81, nitration. The exposure of isolated cardiac mitochondria to ONOO- also led ANT to form high molecular weight proteins and dissociation of ANT from VDAC1. We found that IR injury in isolated hearts, hypoxic injury in H9c2 cells, and ONOO- treatment of H9c2 cells and isolated mitochondria, each decreased mitochondrial bound-hexokinase II (HK II), which suggests that ONOO- caused HK II to dissociate from mitochondria. Moreover, we found that mitochondria exposed to ONOO- induced VDAC1 oligomerization which may decrease its binding with HK II. We have reported that ONOO- produced during cardiac IR injury induced tyrosine nitration of VDAC1, which resulted in conformational changes of the protein and increased channel conductance associated with compromised cardiac function on reperfusion. Thus, our results imply that ONOO- produced during IR injury and hypoxic stress impeded HK II association with VDAC1. ONOO- exposure nitrated mitochondrial proteins and also led to cytochrome c (cyt c) release from mitochondria. In addition, in isolated mitochondria exposed to ONOO- or obtained after IR, there was significant compromise in mitochondrial respiration and delayed repolarization of membrane potential during oxidative (ADP) phosphorylation. Taken together, ONOO- produced during cardiac IR injury can nitrate tyrosine residues of two key mitochondrial membrane proteins involved in bioenergetics and energy transfer to contribute to mitochondrial and cellular dysfunction.
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Affiliation(s)
- Meiying Yang
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Yanji Xu
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Preventive Medicine, Medical College of Yanbian University, Yanji, Jilin, China
| | - James S Heisner
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jie Sun
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA; Institute of Clinical Medicine Research, Suzhou Hospital affiliated with Nanjing Medical University, Suzhou, Jiangsu, China; Department of Gastroenterology and Hepatology, Suzhou Hospital affiliated with Nanjing Medical University, Suzhou, Jiangsu, China
| | - David F Stowe
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Biomedical Engineering, Medical College of Wisconsin and Marquette University, Milwaukee, WI, USA; Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, USA; Research Service, Zablocki VA Medical Center, Milwaukee, WI, USA
| | - Wai-Meng Kwok
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, USA; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, USA; Cancer Center, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Amadou K S Camara
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, USA; Cancer Center, Medical College of Wisconsin, Milwaukee, WI, USA.
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22
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Berry BJ, Trewin AJ, Amitrano AM, Kim M, Wojtovich AP. Use the Protonmotive Force: Mitochondrial Uncoupling and Reactive Oxygen Species. J Mol Biol 2018; 430:3873-3891. [PMID: 29626541 DOI: 10.1016/j.jmb.2018.03.025] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/21/2018] [Accepted: 03/26/2018] [Indexed: 02/06/2023]
Abstract
Mitochondrial respiration results in an electrochemical proton gradient, or protonmotive force (pmf), across the mitochondrial inner membrane. The pmf is a form of potential energy consisting of charge (∆ψm) and chemical (∆pH) components, that together drive ATP production. In a process called uncoupling, proton leak into the mitochondrial matrix independent of ATP production dissipates the pmf and energy is lost as heat. Other events can directly dissipate the pmf independent of ATP production as well, such as chemical exposure or mechanisms involving regulated mitochondrial membrane electrolyte transport. Uncoupling has defined roles in metabolic plasticity and can be linked through signal transduction to physiologic events. In the latter case, the pmf impacts mitochondrial reactive oxygen species (ROS) production. Although capable of molecular damage, ROS also have signaling properties that depend on the timing, location, and quantity of their production. In this review, we provide a general overview of mitochondrial ROS production, mechanisms of uncoupling, and how these work in tandem to affect physiology and pathologies, including obesity, cardiovascular disease, and immunity. Overall, we highlight that isolated bioenergetic models-mitochondria and cells-only partially recapitulate the complex link between the pmf and ROS signaling that occurs in vivo.
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Affiliation(s)
- Brandon J Berry
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA.
| | - Adam J Trewin
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA.
| | - Andrea M Amitrano
- Department of Pathology, University of Rochester Medical Center, Box 609, 601 Elmwood Ave., Rochester, NY 14642, USA; Department of Microbiology and Immunology, University of Rochester Medical Center, Box 609, 601 Elmwood Ave., Rochester, NY 14642, USA.
| | - Minsoo Kim
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA; Department of Pathology, University of Rochester Medical Center, Box 609, 601 Elmwood Ave., Rochester, NY 14642, USA; Department of Microbiology and Immunology, University of Rochester Medical Center, Box 609, 601 Elmwood Ave., Rochester, NY 14642, USA.
| | - Andrew P Wojtovich
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA; Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA.
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Stowe DF, Yang M, Heisner JS, Camara AK. Endogenous and Agonist-induced Opening of Mitochondrial Big Versus Small Ca2+-sensitive K+ Channels on Cardiac Cell and Mitochondrial Protection. J Cardiovasc Pharmacol 2017; 70:314-328. [PMID: 28777255 PMCID: PMC5726766 DOI: 10.1097/fjc.0000000000000524] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Both big (BKCa) and small (SKCa) conductance Ca-sensitive K channels are present in mammalian cardiac cell mitochondria (m). We used pharmacological agonists and antagonists of BKCa and SKCa channels to examine the importance of endogenous opening of these channels and the relative contribution of either or both of these channels to protect against contractile dysfunction and reduce infarct size after ischemia reperfusion (IR) injury through a mitochondrial protective mechanism. After global cardiac IR injury of ex vivo perfused Guinea pig hearts, we found the following: both agonists NS1619 (for BKCa) and DCEB (for SKCa) improved contractility; BKCa antagonist paxilline (PAX) alone or with SKCa antagonist NS8593 worsened contractility and enhanced infarct size; both antagonists PAX and NS8593 obliterated protection by their respective agonists; BKCa and SKCa antagonists did not block protection afforded by SKCa and BKCa agonists, respectively; and all protective effects by the agonists were blocked by scavenging superoxide anions (O2) with Mn(III) tetrakis (4-benzoic acid) porphyrin (TBAP). Contractile function was inversely associated with global infarct size. In in vivo rats, infusion of NS8593, PAX, or both antagonists enhanced regional infarct size while infusion of either NS1619 or DCEB reduced infarct size. In cardiac mitochondria isolated from ex vivo hearts after IR, combined SKCa and BKCa agonists improved respiratory control index and Ca retention capacity compared with IR alone, whereas the combined antagonists did not alter respiratory control index but worsened Ca retention capacity. Although the differential protective bioenergetics effects of endogenous or exogenous BKCa and SKCa channel opening remain unclear, each channel likely responds to different sensing Ca concentrations and voltage gradients over time during oxidative stress-induced injury to individually or together protect cardiac mitochondria and myocytes.
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Affiliation(s)
- David F. Stowe
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
- Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, WI, USA
- Cardiovascular Center, The Medical College of Wisconsin, Milwaukee, WI, USA
- Research Service, Zablocki VA Medical Center, Milwaukee, WI, USA
| | - Meiying Yang
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - James S. Heisner
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Amadou K.S. Camara
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
- Cardiovascular Center, The Medical College of Wisconsin, Milwaukee, WI, USA
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Javadov S, Chapa-Dubocq X, Makarov V. Different approaches to modeling analysis of mitochondrial swelling. Mitochondrion 2017; 38:58-70. [PMID: 28802667 DOI: 10.1016/j.mito.2017.08.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/21/2017] [Accepted: 08/08/2017] [Indexed: 12/11/2022]
Abstract
Mitochondria are critical players involved in both cell life and death through multiple pathways. Structural integrity, metabolism and function of mitochondria are regulated by matrix volume due to physiological changes of ion homeostasis in cellular cytoplasm and mitochondria. Ca2+ and K+ presumably play a critical role in physiological and pathological swelling of mitochondria when increased uptake (influx)/decreased release (efflux) of these ions enhances osmotic pressure accompanied by high water accumulation in the matrix. Changes in the matrix volume in the physiological range have a stimulatory effect on electron transfer chain and oxidative phosphorylation to satisfy metabolic requirements of the cell. However, excessive matrix swelling associated with the sustained opening of mitochondrial permeability transition pores (PTP) and other PTP-independent mechanisms compromises mitochondrial function and integrity leading to cell death. The mechanisms of transition from reversible (physiological) to irreversible (pathological) swelling of mitochondria remain unknown. Mitochondrial swelling is involved in the pathogenesis of many human diseases such as neurodegenerative and cardiovascular diseases. Therefore, modeling analysis of the swelling process is important for understanding the mechanisms of cell dysfunction. This review attempts to describe the role of mitochondrial swelling in cell life and death and the main mechanisms involved in the maintenance of ion homeostasis and swelling. The review also summarizes and discusses different kinetic models and approaches that can be useful for the development of new models for better simulation and prediction of in vivo mitochondrial swelling.
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Affiliation(s)
- Sabzali Javadov
- Department of Physiology, School of Medicine, University of Puerto Rico, San Juan, PR, USA.
| | - Xavier Chapa-Dubocq
- Department of Physiology, School of Medicine, University of Puerto Rico, San Juan, PR, USA
| | - Vladimir Makarov
- Department of Physics, Rio Piedras Campus, University of Puerto Rico, San Juan, PR, USA
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Krabbendam IE, Honrath B, Culmsee C, Dolga AM. Mitochondrial Ca 2+-activated K + channels and their role in cell life and death pathways. Cell Calcium 2017; 69:101-111. [PMID: 28818302 DOI: 10.1016/j.ceca.2017.07.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Revised: 07/14/2017] [Accepted: 07/14/2017] [Indexed: 12/18/2022]
Abstract
Ca2+-activated K+ channels (KCa) are expressed at the plasma membrane and in cellular organelles. Expression of all KCa channel subtypes (BK, IK and SK) has been detected at the inner mitochondrial membrane of several cell types. Primary functions of these mitochondrial KCa channels include the regulation of mitochondrial ROS production, maintenance of the mitochondrial membrane potential and preservation of mitochondrial calcium homeostasis. These channels are therefore thought to contribute to cellular protection against oxidative stress through mitochondrial mechanisms of preconditioning. In this review, we summarize the current knowledge on mitochondrial KCa channels, and their role in mitochondrial function in relation to cell death and survival pathways. More specifically, we systematically discuss studies on the role of these mitochondrial KCa channels in pharmacological preconditioning, and according protective effects on ischemic insults to the brain and the heart.
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Affiliation(s)
- Inge E Krabbendam
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands.
| | - Birgit Honrath
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands; Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany.
| | - Carsten Culmsee
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany.
| | - Amalia M Dolga
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands.
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