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Trębińska-Stryjewska A, Wakula M, Chmielarczyk M, Grzybowska EA. HAX1: A versatile, intrinsically disordered regulatory protein. Biochim Biophys Acta Mol Cell Res 2023; 1870:119538. [PMID: 37454914 DOI: 10.1016/j.bbamcr.2023.119538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/20/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023]
Abstract
HAX1 is a relatively small, ubiquitously expressed, predominantly mitochondrial, intrinsically disordered protein. It has been implicated in the regulation of apoptosis, cell migration, calcium cycling, proteostasis, angiogenesis, autophagy and translation. A wide spectrum of functions, numerous interactions and still elusive molecular mechanisms of action make HAX1 an intriguing subject of research. Moreover, HAX1 is involved in the pathogenesis of diseases; its deficiency leads to neutropenia and its overexpression is associated with cancer. In this review we aim to describe the characteristics of HAX1 gene and protein, and comprehensively discuss its multiple functions, highlighting the emerging role of HAX1 in protection from stress and apoptosis through maintaining cellular proteostasis and homeostasis.
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Affiliation(s)
| | - Maciej Wakula
- Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland
| | | | - Ewa A Grzybowska
- Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland.
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2
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Romero-Tejeda M, Fonoudi H, Weddle CJ, DeKeyser JM, Lenny B, Fetterman KA, Magdy T, Sapkota Y, Epting CL, Burridge PW. A novel transcription factor combination for direct reprogramming to a spontaneously contracting human cardiomyocyte-like state. J Mol Cell Cardiol 2023; 182:30-43. [PMID: 37421991 PMCID: PMC10495191 DOI: 10.1016/j.yjmcc.2023.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 06/06/2023] [Accepted: 06/27/2023] [Indexed: 07/10/2023]
Abstract
The reprogramming of somatic cells to a spontaneously contracting cardiomyocyte-like state using defined transcription factors has proven successful in mouse fibroblasts. However, this process has been less successful in human cells, thus limiting the potential clinical applicability of this technology in regenerative medicine. We hypothesized that this issue is due to a lack of cross-species concordance between the required transcription factor combinations for mouse and human cells. To address this issue, we identified novel transcription factor candidates to induce cell conversion between human fibroblasts and cardiomyocytes, using the network-based algorithm Mogrify. We developed an automated, high-throughput method for screening transcription factor, small molecule, and growth factor combinations, utilizing acoustic liquid handling and high-content kinetic imaging cytometry. Using this high-throughput platform, we screened the effect of 4960 unique transcription factor combinations on direct conversion of 24 patient-specific primary human cardiac fibroblast samples to cardiomyocytes. Our screen revealed the combination of MYOCD, SMAD6, and TBX20 (MST) as the most successful direct reprogramming combination, which consistently produced up to 40% TNNT2+ cells in just 25 days. Addition of FGF2 and XAV939 to the MST cocktail resulted in reprogrammed cells with spontaneous contraction and cardiomyocyte-like calcium transients. Gene expression profiling of the reprogrammed cells also revealed the expression of cardiomyocyte associated genes. Together, these findings indicate that cardiac direct reprogramming in human cells can be achieved at similar levels to those attained in mouse fibroblasts. This progress represents a step forward towards the clinical application of the cardiac direct reprogramming approach.
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Affiliation(s)
- Marisol Romero-Tejeda
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Pharmacogenomics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Hananeh Fonoudi
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Pharmacogenomics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Carly J Weddle
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Pharmacogenomics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Jean-Marc DeKeyser
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Pharmacogenomics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Brian Lenny
- Department of Epidemiology and Cancer Control, St. Jude Children's Hospital, Memphis, TN, USA
| | - K Ashley Fetterman
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Pharmacogenomics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Tarek Magdy
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Pharmacogenomics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Yadav Sapkota
- Department of Epidemiology and Cancer Control, St. Jude Children's Hospital, Memphis, TN, USA
| | - Conrad L Epting
- Departments of Pediatrics and Pathology, Northwestern University and Ann & Robert H.Lurie Children's Hospital of Chicago, Chicago, IL 60611, USA
| | - Paul W Burridge
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Pharmacogenomics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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Chen BB, Li SL, Pogge von Strandmann PAE, Zhong J, Ma TT, Sun J, He WY, Liu CQ. Calcium isotopic geochemistry of geothermal systems in the tectonically active southeastern Tibetan Plateau. Sci Total Environ 2023; 867:161534. [PMID: 36638984 DOI: 10.1016/j.scitotenv.2023.161534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 12/30/2022] [Accepted: 01/07/2023] [Indexed: 06/17/2023]
Abstract
The global Calcium (Ca) cycle is closely coupled to the carbon cycle, and Ca isotopes have potential in tracing it. Even though groundwater is one of the main reservoirs of Ca at the Earth's surface, few data are available for groundwater, and the behavior of Ca and its isotopes in geothermal systems remains unknown. Here we analysed the stable Ca and radiogenic Sr isotope compositions of thermal waters distributed along the Jinsha and Yalong river valleys in the southeastern Tibetan Plateau. The Ca isotopic composition of the thermal water ranges from 0.45 to 2.16 ‰ (δ44/40Ca values relative to SRM 915a). The thermal waters collected from carbonate aquifers have higher δ44/40Ca values than bedrocks, which was attributed to secondary carbonate precipitation accompanied by CO2 degassing. In contrast, δ44/40Ca values in thermal waters collected from clastic and igneous rocks are similar to bedrock. Despite some thermal waters undergoing secondary silicates formation and CaNa ion exchange, such processes maybe not play a significant role in governing the Ca isotopic composition of these thermal waters. This suggests that Ca isotopes can be used to trace secondary carbonate precipitation driven by CO2 degassing (e.g. travertine) in geothermal systems located in tectonically active areas.
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Affiliation(s)
- Bei-Bei Chen
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China; State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing.
| | - Si-Liang Li
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China; State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China.
| | - Philip A E Pogge von Strandmann
- London Geochemistry and Isotope Centre (LOGIC), Institute of Earth and Planetary Sciences, University College London and Birkbeck, University of London, Gower Street, London WC1E 6BT, UK; Institute of Geosciences, Johannes Gutenberg University, 55122 Mainz, Germany
| | - Jun Zhong
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Ting-Ting Ma
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Jian Sun
- Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources, MNR Key Laboratory of Isotope Geology, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
| | - Wen-Yan He
- State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing
| | - Cong-Qiang Liu
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
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Subramanian H, Nikolaev VO. A-Kinase Anchoring Proteins in Cardiac Myocytes and Their Roles in Regulating Calcium Cycling. Cells 2023; 12:cells12030436. [PMID: 36766777 PMCID: PMC9913689 DOI: 10.3390/cells12030436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/22/2023] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
The rate of calcium cycling and calcium transient amplitude are critical determinants for the efficient contraction and relaxation of the heart. Calcium-handling proteins in the cardiac myocyte are altered in heart failure, and restoring the proper function of those proteins is an effective potential therapeutic strategy. The calcium-handling proteins or their regulators are phosphorylated by a cAMP-dependent kinase (PKA), and thereby their activity is regulated. A-Kinase Anchoring Proteins (AKAPs) play a seminal role in orchestrating PKA and cAMP regulators in calcium handling and contractile machinery. This cAMP/PKA orchestration is crucial for the increased force and rate of contraction and relaxation of the heart in response to fight-or-flight. Knockout models and the few available preclinical models proved that the efficient targeting of AKAPs offers potential therapies tailor-made for improving defective calcium cycling. In this review, we highlight important studies that identified AKAPs and their regulatory roles in cardiac myocyte calcium cycling in health and disease.
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Affiliation(s)
- Hariharan Subramanian
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck
- Correspondence: (H.S.); (V.O.N.); Tel.: +49(0)40-7410-57383 (V.O.N.)
| | - Viacheslav O. Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck
- Correspondence: (H.S.); (V.O.N.); Tel.: +49(0)40-7410-57383 (V.O.N.)
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5
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Lin YS, Chen DL, Shaw HM, Wang GJ, Chao PM. Consuming oxidative frying oil impairs cardiac energy production and calcium recycling, causing cardiac hypertrophy, fibrosis and diastolic dysfunction in male Sprague Dawley rats. J Nutr Biochem 2021; 98:108816. [PMID: 34246734 DOI: 10.1016/j.jnutbio.2021.108816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 05/09/2021] [Accepted: 06/23/2021] [Indexed: 12/31/2022]
Abstract
With regards to cardiovascular health, frequent consumption of fried foods is discouraged, despite a lack of clear evidence of a direct link between eating oxidative frying oil (OFO) and cardiovascular diseases. In this study, male Sprague Dawley rats were exposed to diets containing fresh or fried soybean oil (groups C and O, respectively) from in utero to 28 weeks of age. A subset of rats in group O was supplemented with vitamin E (500 mg/kg of DL-α-tocopherol acetate; group OE) from 8 week of age onward to mitigate oxidative stress associated with OFO ingestion. Echocardiography, cardiac histology and indices associated with ATP production and calcium cycling in cardiac tissues were measured. Compared to group C, there was cardiac hypertrophy, fibrosis and diastolic dysfunction, in groups O and OE, with no differences between the latter two groups. Although cardiac mRNA levels of genes associated with mitochondrial biogenesis and function were increased, there were lower ATP concentrations and higher transcripts of uncoupling proteins in groups O and OE than in group C. In addition, decreases in phosphorylation of phospholamban and Ca2+/calmodulin-dependent protein kinase II activity, plus increased protein phosphatase 2A activity in groups O and OE, implied calcium cycling required for cardiac function was disrupted by OFO consumption. We concluded that long-term OFO exposure resulted in cardiac hypertrophy, fibrosis and diastolic dysfunction that was not mitigated by vitamin E supplementation. Underlying mechanisms were partly attributed to inefficient energy production via uncoupled phosphorylation and disrupted calcium cycling.
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Affiliation(s)
- Yu-Shun Lin
- Department of Nutrition, China Medical University, Taichung, Taiwan.
| | - Da-Long Chen
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan; Department of Cardiology, China Medical University Hospital, Taichung, Taiwan
| | - Huey-Mei Shaw
- Department of Health and Nutrition, Chia-Nan University of Pharmacy and Science, Tainan, Taiwan
| | - Guei-Jane Wang
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan; Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan; Department of Medical Research, China Medical University Hospital, Taichung, Taiwan.
| | - Pei-Min Chao
- Department of Nutrition, China Medical University, Taichung, Taiwan.
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Bode D, Semmler L, Wakula P, Hegemann N, Primessnig U, Beindorff N, Powell D, Dahmen R, Ruetten H, Oeing C, Alogna A, Messroghli D, Pieske BM, Heinzel FR, Hohendanner F. Dual SGLT-1 and SGLT-2 inhibition improves left atrial dysfunction in HFpEF. Cardiovasc Diabetol 2021; 20:7. [PMID: 33413413 PMCID: PMC7792219 DOI: 10.1186/s12933-020-01208-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 12/27/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Sodium-glucose linked transporter type 2 (SGLT-2) inhibition has been shown to reduce cardiovascular mortality in heart failure independently of glycemic control and prevents the onset of atrial arrhythmias, a common co-morbidity in heart failure with preserved ejection fraction (HFpEF). The mechanism behind these effects is not fully understood, and it remains unclear if they could be further enhanced by additional SGLT-1 inhibition. We investigated the effects of chronic treatment with the dual SGLT-1&2 inhibitor sotagliflozin on left atrial (LA) remodeling and cellular arrhythmogenesis (i.e. atrial cardiomyopathy) in a metabolic syndrome-related rat model of HFpEF. METHODS 17 week-old ZSF-1 obese rats, a metabolic syndrome-related model of HFpEF, and wild type rats (Wistar Kyoto), were fed 30 mg/kg/d sotagliflozin for 6 weeks. At 23 weeks, LA were imaged in-vivo by echocardiography. In-vitro, Ca2+ transients (CaT; electrically stimulated, caffeine-induced) and spontaneous Ca2+ release were recorded by ratiometric microscopy using Ca2+-sensitive fluorescent dyes (Fura-2) during various experimental protocols. Mitochondrial structure (dye: Mitotracker), Ca2+ buffer capacity (dye: Rhod-2), mitochondrial depolarization (dye: TMRE) and production of reactive oxygen species (dye: H2DCF) were visualized by confocal microscopy. Statistical analysis was performed with 2-way analysis of variance followed by post-hoc Bonferroni and student's t-test, as applicable. RESULTS Sotagliflozin ameliorated LA enlargement in HFpEF in-vivo. In-vitro, LA cardiomyocytes in HFpEF showed an increased incidence and amplitude of arrhythmic spontaneous Ca2+ release events (SCaEs). Sotagliflozin significantly reduced the magnitude of SCaEs, while their frequency was unaffected. Sotagliflozin lowered diastolic [Ca2+] of CaT at baseline and in response to glucose influx, possibly related to a ~ 50% increase of sodium sodium-calcium exchanger (NCX) forward-mode activity. Sotagliflozin prevented mitochondrial swelling and enhanced mitochondrial Ca2+ buffer capacity in HFpEF. Sotagliflozin improved mitochondrial fission and reactive oxygen species (ROS) production during glucose starvation and averted Ca2+ accumulation upon glycolytic inhibition. CONCLUSION The SGLT-1&2 inhibitor sotagliflozin ameliorated LA remodeling in metabolic HFpEF. It also improved distinct features of Ca2+-mediated cellular arrhythmogenesis in-vitro (i.e. magnitude of SCaEs, mitochondrial Ca2+ buffer capacity, diastolic Ca2+ accumulation, NCX activity). The safety and efficacy of combined SGLT-1&2 inhibition for the treatment and/or prevention of atrial cardiomyopathy associated arrhythmias should be further evaluated in clinical trials.
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MESH Headings
- Animals
- Arrhythmias, Cardiac/etiology
- Arrhythmias, Cardiac/metabolism
- Arrhythmias, Cardiac/physiopathology
- Arrhythmias, Cardiac/prevention & control
- Atrial Function, Left/drug effects
- Atrial Remodeling/drug effects
- Calcium Signaling/drug effects
- Disease Models, Animal
- Glycosides/pharmacology
- Heart Atria/drug effects
- Heart Atria/metabolism
- Heart Atria/physiopathology
- Heart Failure/drug therapy
- Heart Failure/etiology
- Heart Failure/metabolism
- Heart Failure/physiopathology
- Metabolic Syndrome/complications
- Mitochondria, Heart/drug effects
- Mitochondria, Heart/metabolism
- Mitochondria, Heart/pathology
- Mitochondrial Dynamics/drug effects
- Mitochondrial Swelling/drug effects
- Rats, Inbred WKY
- Rats, Zucker
- Reactive Oxygen Species/metabolism
- Sodium-Calcium Exchanger/metabolism
- Sodium-Glucose Transporter 1/antagonists & inhibitors
- Sodium-Glucose Transporter 1/metabolism
- Sodium-Glucose Transporter 2/metabolism
- Sodium-Glucose Transporter 2 Inhibitors/pharmacology
- Rats
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Affiliation(s)
- David Bode
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Lukas Semmler
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Paulina Wakula
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Niklas Hegemann
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Uwe Primessnig
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Nicola Beindorff
- Berlin Experimental Radionuclide Imaging Center (BERIC), Charité-Universitaetsmedizin Berlin, Berlin, Germany
| | - David Powell
- Lexicon Pharmaceuticals, Metabolism Research, Houston, TX, USA
| | - Raphael Dahmen
- Sanofi-Aventis Deutschland GmbH, Research & Development, 65926, Frankfurt am Main, Germany
| | - Hartmut Ruetten
- Sanofi-Aventis Deutschland GmbH, Research & Development, 65926, Frankfurt am Main, Germany
| | - Christian Oeing
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Alessio Alogna
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Daniel Messroghli
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Department of Internal Medicine and Cardiology, German Heart Center Berlin, 13353, Berlin, Germany
| | - Burkert M Pieske
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Department of Internal Medicine and Cardiology, German Heart Center Berlin, 13353, Berlin, Germany
| | - Frank R Heinzel
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Felix Hohendanner
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany.
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany.
- Berlin Institute of Health (BIH), Berlin, Germany.
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7
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Ciezarek A, Gardner L, Savolainen V, Block B. Skeletal muscle and cardiac transcriptomics of a regionally endothermic fish, the Pacific bluefin tuna, Thunnus orientalis. BMC Genomics 2020; 21:642. [PMID: 32942994 PMCID: PMC7499911 DOI: 10.1186/s12864-020-07058-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 09/08/2020] [Indexed: 11/29/2022] Open
Abstract
Background The Pacific bluefin tuna (Thunnus orientalis) is a regionally endothermic fish that maintains temperatures in their swimming musculature, eyes, brain and viscera above that of the ambient water. Within their skeletal muscle, a thermal gradient exists, with deep muscles, close to the backbone, operating at elevated temperatures compared to superficial muscles near the skin. Their heart, by contrast, operates at ambient temperature, which in bluefin tunas can range widely. Cardiac function in tunas reduces in cold waters, yet the heart must continue to supply blood for metabolically demanding endothermic tissues. Physiological studies indicate Pacific bluefin tuna have an elevated cardiac capacity and increased cold-tolerance compared to warm-water tuna species, primarily enabled by increased capacity for sarcoplasmic reticulum calcium cycling within the cardiac muscles. Results Here, we compare tissue-specific gene-expression profiles of different cardiac and skeletal muscle tissues in Pacific bluefin tuna. There was little difference in the overall expression of calcium-cycling and cardiac contraction pathways between atrium and ventricle. However, expression of a key sarcoplasmic reticulum calcium-cycling gene, SERCA2b, which plays a key role maintaining intracellular calcium stores, was higher in atrium than ventricle. Expression of genes involved in aerobic metabolism and cardiac contraction were higher in the ventricle than atrium. The two morphologically distinct tissues that derive the ventricle, spongy and compact myocardium, had near-identical levels of gene expression. More genes had higher expression in the cool, superficial muscle than in the warm, deep muscle in both the aerobic red muscle (slow-twitch) and anaerobic white muscle (fast-twitch), suggesting thermal compensation. Conclusions We find evidence of widespread transcriptomic differences between the Pacific tuna ventricle and atrium, with potentially higher rates of calcium cycling in the atrium associated with the higher expression of SERCA2b compared to the ventricle. We find no evidence that genes associated with thermogenesis are upregulated in the deep, warm muscle compared to superficial, cool muscle. Heat generation may be enabled by by the high aerobic capacity of bluefin tuna red muscle.
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Affiliation(s)
- Adam Ciezarek
- Department of Life Sciences, Silwood Park Campus, Imperial College London, Ascot, UK. .,Earlham Institute, Norwich Research Park, Norwich, UK.
| | - Luke Gardner
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA
| | - Vincent Savolainen
- Department of Life Sciences, Silwood Park Campus, Imperial College London, Ascot, UK
| | - Barbara Block
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA
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8
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Khadjeh S, Hindmarsh V, Weber F, Cyganek L, Vidal RO, Torkieh S, Streckfuss-Bömeke K, Lbik D, Tiburcy M, Mohamed BA, Bonn S, Toischer K, Hasenfuss G. CRISPLD1: a novel conserved target in the transition to human heart failure. Basic Res Cardiol 2020; 115:27. [PMID: 32146539 DOI: 10.1007/s00395-020-0784-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 02/20/2020] [Indexed: 12/12/2022]
Abstract
Heart failure is a major health problem worldwide with a significant morbidity and mortality rate. Although studied extensively in animal models, data from patients at the compensated disease stage are lacking. We sampled myocardium biopsies from aortic stenosis patients with compensated hypertrophy and moderate heart failure and used transcriptomics to study the transition to failure. Sequencing and comparative analysis of analogous samples of mice with transverse aortic constriction identified 25 candidate genes with similar regulation in response to pressure overload, reflecting highly conserved molecular processes. The gene cysteine-rich secretory protein LCCL domain containing 1 (CRISPLD1) is upregulated in the transition to failure in human and mouse and its function is unknown. Homology to ion channel regulatory toxins suggests a role in Ca2+ cycling. CRISPR/Cas9-mediated loss-of-function leads to dysregulated Ca2+ handling in human-induced pluripotent stem cell-derived cardiomyocytes. The downregulation of prohypertrophic, proapoptotic and Ca2+-signaling pathways upon CRISPLD1-KO and its upregulation in the transition to failure implicates a contribution to adverse remodeling. These findings provide new pathophysiological data on Ca2+ regulation in the transition to failure and novel candidate genes with promising potential for therapeutic interventions.
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9
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Ebner J, Cagalinec M, Kubista H, Todt H, Szabo PL, Kiss A, Podesser BK, Cserne Szappanos H, Hool LC, Hilber K, Koenig X. Neuronal nitric oxide synthase regulation of calcium cycling in ventricular cardiomyocytes is independent of Ca v1.2 channel modulation under basal conditions. Pflugers Arch 2020; 472:61-74. [PMID: 31822999 PMCID: PMC6960210 DOI: 10.1007/s00424-019-02335-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 11/19/2019] [Accepted: 11/21/2019] [Indexed: 11/25/2022]
Abstract
Neuronal nitric oxide synthase (nNOS) is considered a regulator of Cav1.2 L-type Ca2+ channels and downstream Ca2+ cycling in the heart. The commonest view is that nitric oxide (NO), generated by nNOS activity in cardiomyocytes, reduces the currents through Cav1.2 channels. This gives rise to a diminished Ca2+ release from the sarcoplasmic reticulum, and finally reduced contractility. Here, we report that nNOS inhibitor substances significantly increase intracellular Ca2+ transients in ventricular cardiomyocytes derived from adult mouse and rat hearts. This is consistent with an inhibitory effect of nNOS/NO activity on Ca2+ cycling and contractility. Whole cell currents through L-type Ca2+ channels in rodent myocytes, on the other hand, were not substantially affected by the application of various NOS inhibitors, or application of a NO donor substance. Moreover, the presence of NO donors had no effect on the single-channel open probability of purified human Cav1.2 channel protein reconstituted in artificial liposomes. These results indicate that nNOS/NO activity does not directly modify Cav1.2 channel function. We conclude that-against the currently prevailing view-basal Cav1.2 channel activity in ventricular cardiomyocytes is not substantially regulated by nNOS activity and NO. Hence, nNOS/NO inhibition of Ca2+ cycling and contractility occurs independently of direct regulation of Cav1.2 channels by NO.
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Affiliation(s)
- Janine Ebner
- Department of Neurophysiology and-Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstraße 17, 1090, Vienna, Austria
| | - Michal Cagalinec
- Department of Cellular Cardiology, Institute of Experimental Endocrinology, Biomedical Research Center, University Science Park for Biomedicine, Slovak Academy of Sciences, Bratislava, Slovakia
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Helmut Kubista
- Department of Neurophysiology and-Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstraße 17, 1090, Vienna, Austria
| | - Hannes Todt
- Department of Neurophysiology and-Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstraße 17, 1090, Vienna, Austria
| | - Petra L Szabo
- Ludwig Boltzmann Cluster for Cardiovascular Research at the Center for Biomedical Research, Medical University of Vienna, Vienna, Austria
| | - Attila Kiss
- Ludwig Boltzmann Cluster for Cardiovascular Research at the Center for Biomedical Research, Medical University of Vienna, Vienna, Austria
| | - Bruno K Podesser
- Ludwig Boltzmann Cluster for Cardiovascular Research at the Center for Biomedical Research, Medical University of Vienna, Vienna, Austria
| | | | - Livia C Hool
- School of Human Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, 2010, Australia
| | - Karlheinz Hilber
- Department of Neurophysiology and-Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstraße 17, 1090, Vienna, Austria.
| | - Xaver Koenig
- Department of Neurophysiology and-Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstraße 17, 1090, Vienna, Austria
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10
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Jaimes R, McCullough D, Siegel B, Swift L, Hiebert J, Mclnerney D, Posnack NG. Lights, camera, path splitter: a new approach for truly simultaneous dual optical mapping of the heart with a single camera. BMC Biomed Eng 2019; 1. [PMID: 31768502 PMCID: PMC6876868 DOI: 10.1186/s42490-019-0024-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Background Optical mapping of transmembrane voltage and intracellular calcium is a powerful tool for investigating cardiac physiology and pathophysiology. However, simultaneous dual mapping of two fluorescent probes remains technically challenging. We introduce a novel, easy-to-use approach that requires a path splitter, single camera and excitation light to simultaneously acquire voltage and calcium signals from whole heart preparations, which can be applied to other physiological models – including neurons and isolated cardiomyocytes. Results Complementary probes were selected that could be excited with a single wavelength light source. Langendorff-perfused hearts (rat, swine) were stained and imaged using a sCMOS camera outfitted with an optical path splitter to simultaneously acquire two emission fields at high spatial and temporal resolution. Voltage (RH237) and calcium (Rhod2) signals were acquired concurrently on a single sensor, resulting in two 384 × 256 images at 814 frames per second. At this frame rate, the signal-to-noise ratio was 47 (RH237) and 85 (Rhod2). Imaging experiments were performed on small rodent hearts, as well as larger pig hearts with sufficient optical signals. In separate experiments, each dye was used independently to assess crosstalk and demonstrate signal specificity. Additionally, the effect of ryanodine on myocardial calcium transients was validated – with no measurable effect on the amplitude of optical action potentials. To demonstrate spatial resolution, ventricular tachycardia was induced –resulting in the novel finding that spatially discordant calcium alternans can be present in different regions of the heart, even when electrical alternans remain concordant. The described system excels in providing a wide field of view and high spatiotemporal resolution for a variety of cardiac preparations. Conclusions We report the first multiparametric mapping system that simultaneously acquires calcium and voltage signals from cardiac preparations, using a path splitter, single camera and excitation light. This approach eliminates the need for multiple cameras, excitation light patterning or frame interleaving. These features can aid in the adoption of dual mapping technology by the broader cardiovascular research community, and decrease the barrier of entry into panoramic heart imaging, as it reduces the number of required cameras. Electronic supplementary material The online version of this article (10.1186/s42490-019-0024-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rafael Jaimes
- Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA.,Children's National Heart Institute: Children's National Health System, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Damon McCullough
- Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Bryan Siegel
- Children's National Heart Institute: Children's National Health System, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Luther Swift
- Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA.,Children's National Heart Institute: Children's National Health System, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - James Hiebert
- Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Daniel Mclnerney
- Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Nikki Gillum Posnack
- Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA.,Children's National Heart Institute: Children's National Health System, 111 Michigan Avenue NW, Washington, DC 20010, USA.,Department of Pediatrics, Department of Pharmacology & Physiology, School of Medicine and Health Sciences: George Washington University, 2300 I Street NW, Washington, DC 20037, USA
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11
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Fukaya H, Plummer BN, Piktel JS, Wan X, Rosenbaum DS, Laurita KR, Wilson LD. Arrhythmogenic cardiac alternans in heart failure is suppressed by late sodium current blockade by ranolazine. Heart Rhythm 2019; 16:281-289. [PMID: 30193854 DOI: 10.1016/j.hrthm.2018.08.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Indexed: 12/19/2022]
Abstract
BACKGROUND Cardiac alternans is promoted by heart failure (HF)-induced calcium (Ca2+) cycling abnormalities. Late sodium current (INa,L) is enhanced in HF and promotes Ca2+ overload; however, mechanisms underlying an antiarrhythmic effect of INa,L blockade in HF remain unclear. OBJECTIVE The purpose of this study was to determine whether ranolazine suppresses cardiac alternans in HF by normalizing Ca2+ cycling. METHODS Transmural dual optical mapping of Ca2+ transients and action potentials was performed in wedge preparations from 8 HF and 8 control (normal) dogs. Susceptibility to action potential duration alternans (APD-ALT) and Ca2+ transient alternans (Ca-ALT) was compared at baseline and with ranolazine (5-10 μM). RESULTS HF increased APD- and Ca-ALT compared to normal (both P <.05), and ranolazine suppressed APD- and Ca-ALT in both groups (P <.05). The incidence of spatially discordant alternans (DIS-ALT) was increased by HF (8/8) compared to normal (4/8; P <.05), and ranolazine decreased DIS-ALT in HF (4/8; P <.05).Not only did ranolazine mitigate HF-induced Ca2+ overload, it also attenuated APD-ALT to Ca-ALT gain (amount of APD-ALT produced by Ca-ALT). In HF, APD-ALT to Ca-ALT gain was significantly increased (0.55 ± 0.02) compared to normal (0.44 ± 0.02; P <.05) and was normalized by ranolazine (0.36 ± 0.05; P <.05), representing a complementary mechanism by which INa,L blockade suppressed cardiac alternans. CONCLUSION Ranolazine attenuated arrhythmogenic cardiac alternans in HF, both by suppressing Ca-ALT and decreasing the coupling gain of APD-ALT to Ca-ALT. Blockade of INa,L may reverse impaired Ca2+ cycling to mitigate cardiac alternans, representing a mechanism underlying the antiarrhythmic benefit of INa,L blockade in HF.
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Affiliation(s)
- Hidehira Fukaya
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio; Department of Cardiovascular Medicine, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Bradley N Plummer
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio
| | - Joseph S Piktel
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio; Department of Emergency Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio
| | - Xiaoping Wan
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio
| | - David S Rosenbaum
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio
| | - Kenneth R Laurita
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio
| | - Lance D Wilson
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio; Department of Emergency Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio.
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12
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Ford KL, Moorhouse EL, Bortolozzi M, Richards MA, Swietach P, Vaughan-Jones RD. Regional acidosis locally inhibits but remotely stimulates Ca2+ waves in ventricular myocytes. Cardiovasc Res 2018; 113:984-995. [PMID: 28339694 PMCID: PMC5852542 DOI: 10.1093/cvr/cvx033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 02/17/2017] [Indexed: 11/30/2022] Open
Abstract
Aims Spontaneous Ca2+ waves in cardiomyocytes are potentially arrhythmogenic. A
powerful controller of Ca2+ waves is the cytoplasmic H+
concentration ([H+]i), which fluctuates spatially and temporally
in conditions such as myocardial ischaemia/reperfusion. H+-control of
Ca2+ waves is poorly understood. We have therefore investigated how
[H+]i co-ordinates their initiation and frequency. Methods and results Spontaneous Ca2+ waves were imaged (fluo-3) in rat isolated ventricular
myocytes, subjected to modest Ca2+-overload. Whole-cell intracellular
acidosis (induced by acetate-superfusion) stimulated wave frequency. Pharmacologically
blocking sarcolemmal Na+/H+ exchange (NHE1) prevented this
stimulation, unveiling inhibition by H+. Acidosis also increased
Ca2+ wave velocity. Restricting acidosis to one end of a myocyte, using a
microfluidic device, inhibited Ca2+ waves in the acidic zone (consistent with
ryanodine receptor inhibition), but stimulated wave emergence elsewhere in the cell.
This remote stimulation was absent when NHE1 was selectively inhibited in the acidic
zone. Remote stimulation depended on a locally evoked, NHE1-driven rise of
[Na+]i that spread rapidly downstream. Conclusion Acidosis influences Ca2+ waves via inhibitory Hi+ and stimulatory Nai+ signals (the latter facilitating intracellular
Ca2+-loading through modulation of sarcolemmal
Na+/Ca2+ exchange activity). During spatial
[H+]i-heterogeneity, Hi+-inhibition dominates in acidic regions, while rapid
Nai+ diffusion stimulates waves in downstream, non-acidic
regions. Local acidosis thus simultaneously inhibits and stimulates arrhythmogenic
Ca2+-signalling in the same myocyte. If the principle of remote
H+-stimulation of Ca2+ waves also applies in multicellular
myocardium, it raises the possibility of electrical disturbances being driven remotely
by adjacent ischaemic areas, which are known to be intensely acidic.
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Affiliation(s)
- Kerrie L Ford
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK
| | - Emma L Moorhouse
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK
| | - Mario Bortolozzi
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK.,Department of Physics and Astronomy "G. Galilei", University of Padua, 35121 Padua, Italy
| | - Mark A Richards
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK
| | - Pawel Swietach
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK
| | - Richard D Vaughan-Jones
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK
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13
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Song Z, Liu MB, Qu Z. Transverse tubular network structures in the genesis of intracellular calcium alternans and triggered activity in cardiac cells. J Mol Cell Cardiol 2017; 114:288-299. [PMID: 29217432 DOI: 10.1016/j.yjmcc.2017.12.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/31/2017] [Accepted: 12/04/2017] [Indexed: 12/20/2022]
Abstract
RATIONALE The major role of a transverse-tubular (TT) network in a cardiac cell is to facilitate effective excitation-contraction coupling and signaling. The TT network structures are heterogeneous within a single cell, and vary between different types of cells and species. They are also remodeled in cardiac diseases. However, how different TT network structures predispose cardiac cells to arrhythmogenesis remains to be revealed. OBJECTIVE To systematically investigate the roles of TT network structure and the underlying mechanisms in the genesis of intracellular calcium (Ca2+) alternans and triggered activity (TA). METHODS AND RESULTS Based on recent experimental observations, different TT network structures, including uniformly and non-uniformly random TT distributions, were modeled in a cardiac cell model consisting of a three-dimensional network of Ca2+ release units (CRUs). Our simulations showed that both Ca2+ alternans and Ca2+ wave-mediated TA were promoted when the fraction of orphaned CRUs was in an intermediate range, but suppressed in cells exhibiting either well-organized TT networks or low TT densities. Ca2+ alternans and TA could be promoted by low TT densities when the cells were small or the CRU coupling was strong. Both alternans and TA occurred more easily in uniformly random TT networks than in non-uniformly random TT networks. Subcellular spatially discordant Ca2+ alternans was promoted by non-uniformly random TT networks but suppressed by increasing CRU coupling strength. These mechanistic insights provide a holistic understanding of the effects of TT network structure on the susceptibility to arrhythmogenesis. CONCLUSIONS The TT network plays important roles in promoting Ca2+ alternans and TA, and different TT network structures may predispose cardiac cells differently to arrhythmogenesis.
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Affiliation(s)
- Zhen Song
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
| | - Michael B Liu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA; Department of Biomathematics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
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14
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Abstract
Obesity and diabetes has become a major epidemic across the globe. Controlling obesity has been a challenge since this would require either increased physical activity or reduced caloric intake; both are difficult to enforce. There has been renewed interest in exploiting pathways such as uncoupling protein 1 (UCP1)-mediated uncoupling in brown adipose tissue (BAT) and white adipose tissue to increase energy expenditure to control weight gain. However, relying on UCP1-based thermogenesis alone may not be sufficient to control obesity in humans. On the other hand, skeletal muscle is the largest organ and a major contributor to basal metabolic rate and increasing energy expenditure in muscle through nonshivering thermogenic mechanisms, which can substantially affect whole body metabolism and weight gain. In this review we will describe the role of Sarcolipin-mediated uncoupling of Sarcoplasmic Reticulum Calcium ATPase (SERCA) as a potential mechanism for increased energy expenditure both during cold and diet-induced thermogenesis.
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Affiliation(s)
- Muthu Periasamy
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, FL, USA.
| | - Jose Luis Herrera
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, FL, USA
| | - Felipe C G Reis
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, FL, USA
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15
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Seebacher F, Borg J, Schlotfeldt K, Yan Z. Energetic cost determines voluntary movement speed only in familiar environments. ACTA ACUST UNITED AC 2017; 219:1625-31. [PMID: 27252454 DOI: 10.1242/jeb.136689] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 03/10/2016] [Indexed: 11/20/2022]
Abstract
Locomotor performance is closely related to fitness. However, in many ecological contexts, animals do not move at their maximal locomotor capacity, but adopt a voluntary speed that is lower than maximal. It is important to understand the mechanisms that underlie voluntary speed, because these determine movement patterns of animals across natural environments. We show that voluntary speed is a stable trait in zebrafish (Danio rerio), but there were pronounced differences between individuals in maximal sustained speed, voluntary speed and metabolic cost of locomotion. We accept the hypothesis that voluntary speed scales positively with maximal sustained swimming performance (Ucrit), but only in unfamiliar environments (1st minute in an open-field arena versus 10th minute) at high temperature (30°C). There was no significant effect of metabolic scope on Ucrit Contrary to expectation, we rejected the hypothesis that voluntary speed decreases with increasing metabolic cost of movement, except in familiar spatial (after 10 min of exploration) and thermal (24°C but not 18 or 30°C) environments. The implications of these data are that the energetic costs of exploration and dispersal in novel environments are higher than those for movement within familiar home ranges.
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Affiliation(s)
- Frank Seebacher
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, NSW 2006, Australia
| | - Jason Borg
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, NSW 2006, Australia
| | - Kathryn Schlotfeldt
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, NSW 2006, Australia
| | - Zhongning Yan
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, NSW 2006, Australia
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16
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Ghanizadeh Kazerouni E, Franklin CE, Seebacher F. UV-B exposure reduces locomotor performance by impairing muscle function but not mitochondrial ATP production. ACTA ACUST UNITED AC 2015; 219:96-102. [PMID: 26567351 DOI: 10.1242/jeb.131615] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 11/01/2015] [Indexed: 11/20/2022]
Abstract
Ultraviolet B radiation (UV-B) can reduce swimming performance by increasing reactive oxygen species (ROS) formation. High concentrations of ROS can damage mitochondria, resulting in reduced ATP production. ROS can also damage muscle proteins, thereby leading to impaired muscle contractile function. We have shown previously that UV-B exposure reduces locomotor performance in mosquitofish (Gambusia holbrooki) without affecting metabolic scope. Our aim was therefore to test whether UV-B influences swimming performance of mosquitofish by ROS-induced damage to muscle proteins without affecting mitochondrial function. In a fully factorial design, we exposed mosquitofish to UV-B and no-UV-B controls in combination with exposure to N-acetylcysteine (NAC) plus no-NAC controls. We used NAC, a precursor of glutathione, as an antioxidant to test whether any effects of UV-B on swimming performance were at least partly due to UV-B-induced ROS. UV-B significantly reduced critical sustained swimming performance and tail beat frequencies, and it increased ROS-induced damage (protein carbonyl concentrations and lipid peroxidation) in muscle. However, UV-B did not affect the activity of sarco-endoplasmic reticulum ATPase (SERCA), an enzyme associated with muscle calcium cycling and muscle relaxation. UV-B did not affect ADP phosphorylation (state 3) rates of mitochondrial respiration, and it did not alter the amount of ATP produced per atom of oxygen consumed (P:O ratio). However, UV-B reduced the mitochondrial respiratory control ratio. Under UV-B exposure, fish treated with NAC showed greater swimming performance and tail beat frequencies, higher glutathione concentrations, and lower protein carbonyl concentrations and lipid peroxidation than untreated fish. Tail beat amplitude was not affected by any treatment. Our results showed, firstly, that the effects of UV-B on locomotor performance were mediated by ROS and, secondly, that reduced swimming performance was not caused by impaired mitochondrial ATP production. Instead, reduced tail beat frequencies indicate that muscle of UV-B exposed fish were slower, which was likely to have been caused by slower contraction rates, because SERCA activities remained unaffected.
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Affiliation(s)
| | - Craig E Franklin
- School of Biological Sciences, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Frank Seebacher
- School of Biological Sciences A08, University of Sydney, New South Wales 2006, Australia
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17
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Fischer TH, Herting J, Eiringhaus J, Pabel S, Hartmann NH, Ellenberger D, Friedrich M, Renner A, Gummert J, Maier LS, Zabel M, Hasenfuss G, Sossalla S. Sex-dependent alterations of Ca2+ cycling in human cardiac hypertrophy and heart failure. Europace 2015; 18:1440-8. [PMID: 26493982 DOI: 10.1093/europace/euv313] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 08/19/2015] [Indexed: 11/12/2022] Open
Abstract
AIMS Clinical studies have shown differences in the propensity for malignant ventricular arrhythmias between women and men suffering from cardiomyopathies and heart failure (HF). This is clinically relevant as it impacts therapies like prophylactic implantable cardioverter-defibrillator implantation but the pathomechanisms are unknown. As an increased sarcoplasmic reticulum (SR) Ca(2+) leak is arrhythmogenic, it could represent a cellular basis for this paradox. METHODS/RESULTS We evaluated the SR Ca(2+) leak with respect to sex differences in (i) afterload-induced cardiac hypertrophy (Hy) with preserved left ventricular (LV) function and (ii) end-stage HF. Cardiac function did not differ between sexes in both cardiac pathologies. Human cardiomyocytes isolated from female patients with Hy showed a significantly lower Ca(2+) spark frequency (CaSpF, confocal microscopy, Fluo3-AM) compared with men (P < 0.05). As Ca(2+) spark width and duration were similar in women and men, this difference in CaSpF did not yet translate into a significant difference of the calculated SR Ca(2+) leak between both sexes at this stage of disease (P = 0.14). Epifluorescence measurements (Fura2-AM) revealed comparable Ca(2+) cycling properties (diastolic Ca(2+) levels, amplitude of systolic Ca(2+) transients, SR Ca(2+) load) in patients of both sexes suffering from Hy. Additionally, the increased diastolic CaSpF in male patients with Hy did not yet translate into an elevated ratio of cells showing arrhythmic events (Ca(2+) waves, spontaneous Ca(2+) transients) (P = 0.77). In the transition to HF, both sexes showed an increase of the CaSpF (P < 0.05) and the sex dependence was even more pronounced. Female patients had a 69 ± 10% lower SR Ca(2+) leak (P < 0.05), which now even translated into a lower ratio of arrhythmic cells in female HF patients compared with men (P < 0.001). CONCLUSION These data show that the SR Ca(2+) leak is lower in women than in men with comparable cardiac impairment. Since the SR Ca(2+) leak triggers delayed afterdepolarizations, our findings may explain why women are less prone to ventricular arrhythmias and confirm the rationale of therapeutic measures reducing the SR Ca(2+) leak.
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Affiliation(s)
- Thomas H Fischer
- Klinik für Kardiologie und Pneumologie/Herzzentrum, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Jonas Herting
- Klinik für Kardiologie und Pneumologie/Herzzentrum, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Jörg Eiringhaus
- Klinik für Kardiologie und Pneumologie/Herzzentrum, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Steffen Pabel
- Klinik für Kardiologie und Pneumologie/Herzzentrum, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Nico H Hartmann
- Klinik für Kardiologie und Pneumologie/Herzzentrum, Georg-August-Universität Göttingen, Göttingen, Germany
| | - David Ellenberger
- Institut für Medizinische Statistik, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Martin Friedrich
- Abt. Thorax-, Herz- und Gefäßchirurgie, Herzzentrum, Georg-August-Universität Göttingen, Göttingen, Germany
| | - André Renner
- Abt. Thorax-, Herz-, Gefäßchirurgie, Herz- und Diabeteszentrum Nordrheinwestfalen, Bad Oeynhausen, Germany
| | - Jan Gummert
- Abt. Thorax-, Herz-, Gefäßchirurgie, Herz- und Diabeteszentrum Nordrheinwestfalen, Bad Oeynhausen, Germany
| | - Lars S Maier
- Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany
| | - Markus Zabel
- Klinik für Kardiologie und Pneumologie/Herzzentrum, Georg-August-Universität Göttingen, Göttingen, Germany Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK), Standort Göttingen, Germany
| | - Gerd Hasenfuss
- Klinik für Kardiologie und Pneumologie/Herzzentrum, Georg-August-Universität Göttingen, Göttingen, Germany Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK), Standort Göttingen, Germany
| | - Samuel Sossalla
- Klinik für Kardiologie und Pneumologie/Herzzentrum, Georg-August-Universität Göttingen, Göttingen, Germany Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK), Standort Göttingen, Germany
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18
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Haghighi K, Pritchard TJ, Liu GS, Singh VP, Bidwell P, Lam CK, Vafiadaki E, Das P, Ma J, Kunduri S, Sanoudou D, Florea S, Vanderbilt E, Wang HS, Rubinstein J, Hajjar RJ, Kranias EG. Human G109E-inhibitor-1 impairs cardiac function and promotes arrhythmias. J Mol Cell Cardiol 2015; 89:349-59. [PMID: 26455482 DOI: 10.1016/j.yjmcc.2015.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 09/18/2015] [Accepted: 10/04/2015] [Indexed: 01/09/2023]
Abstract
A hallmark of human and experimental heart failure is deficient sarcoplasmic reticulum (SR) Ca-uptake reflecting impaired contractile function. This is at least partially attributed to dephosphorylation of phospholamban by increased protein phosphatase 1 (PP1) activity. Indeed inhibition of PP1 by transgenic overexpression or gene-transfer of constitutively active inhibitor-1 improved Ca-cycling, preserved function and decreased fibrosis in small and large animal models of heart failure, suggesting that inhibitor-1 may represent a potential therapeutic target. We recently identified a novel human polymorphism (G109E) in the inhibitor-1 gene with a frequency of 7% in either normal or heart failure patients. Transgenic mice, harboring cardiac-specific expression of G109E inhibitor-1, exhibited decreases in contractility, Ca-kinetics and SR Ca-load. These depressive effects were relieved by isoproterenol stimulation. Furthermore, stress conditions (2Hz +/- Iso) induced increases in Ca-sparks, Ca-waves (60% of G109E versus 20% in wild types) and after-contractions (76% of G109E versus 23% of wild types) in mutant cardiomyocytes. Similar findings were obtained by acute expression of the G109E variant in adult cardiomyocytes in the absence or presence of endogenous inhibitor-1. The underlying mechanisms included reduced binding of mutant inhibitor-1 to PP1, increased PP1 activity, and dephosphorylation of phospholamban at Ser16 and Thr17. However, phosphorylation of the ryanodine receptor at Ser2808 was not altered while phosphorylation at Ser2814 was increased, consistent with increased activation of Ca/calmodulin-dependent protein kinase II (CaMKII), promoting aberrant SR Ca-release. Parallel in vivo studies revealed that mutant mice developed ventricular ectopy and complex ventricular arrhythmias (including bigeminy, trigeminy and ventricular tachycardia), when challenged with isoproterenol. Inhibition of CaMKII activity by KN-93 prevented the increased propensity to arrhythmias. These findings suggest that the human G109E inhibitor-1 variant impairs SR Ca-cycling and promotes arrhythmogenesis under stress conditions, which may present an additional insult in the compromised function of heart failure carriers.
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19
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Cai WF, Liu GS, Lam CK, Florea S, Qian J, Zhao W, Pritchard T, Haghighi K, Lebeche D, Lu LJ, Deng J, Fan GC, Hajjar RJ, Kranias EG. Up-regulation of micro-RNA765 in human failing hearts is associated with post-transcriptional regulation of protein phosphatase inhibitor-1 and depressed contractility. Eur J Heart Fail 2015; 17:782-93. [PMID: 26177627 DOI: 10.1002/ejhf.323] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 03/18/2015] [Accepted: 04/17/2015] [Indexed: 11/09/2022] Open
Abstract
AIMS Impaired sarcoplasmic reticulum (SR) Ca(2+) cycling and depressed contractility, a hallmark of human and experimental heart failure, has been partially attributed to increased protein phosphatase 1 (PP-1) activity, associated with down-regulation of its endogenous inhibitor-1. The levels and activity of inhibitor-1 are reduced in failing hearts, contributing to dephosphorylation and inactivation of key calcium cycling proteins. Therefore, we investigated the mechanisms that mediate decreases in inhibitor-1 by post-transcriptional modification. METHODS AND RESULTS Bioinformatics revealed that 17 human microRNAs may serve as modulators of inhibitor-1. However, real-time PCR analysis identified only one of these microRNAs, miR-765, as being increased in human failing hearts concomitant with decreased inhibitor-1 levels. Expression of miR-765 in HEK293 cells or mouse ventricular myocytes confirmed suppression of inhibitor-1 levels through binding of this miR-765 to the 3'-untranslated region of inhibitor-1 mRNA. To determine the functional significance of miR-765 in Ca(2+) cycling, pri-miR-765 as well as a non-translated nucleotide sequence (miR-Ctrl) were expressed in adult mouse ventricular myocytes. The inhibitor-1 expression levels were decreased, accompanied by enhanced PP-1 activity in the miR-765 cardiomyocytes, and these reflected depressed contractile mechanics and Ca(2+) transients, compared with the miR-Ctrl group. The depressive effects were associated with decreases in the phosphorylation of phospholamban and SR Ca(2+) load. These miR-765 negative inotropic effects were abrogated in inhibitor-1-deficient cardiomyocytes, suggesting its apparent specificity for inhibitor-1. CONCLUSIONS miR-765 levels are increased in human failing hearts. Such increases may contribute to depressed cardiac function through reduced inhibitor-1 expression and enhanced PP-1 activity, associated with reduced SR Ca(2+) load.
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Affiliation(s)
- Wen-Feng Cai
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Guan-Sheng Liu
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Chi Keung Lam
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Stela Florea
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Jiang Qian
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Wen Zhao
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Tracy Pritchard
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Kobra Haghighi
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Djamel Lebeche
- Cardiovascular Research Center, Mount Sinai School of Medicine, New York, NY, USA
| | - Long Jason Lu
- Division of Biomedical Informatics, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH, USA
| | - Jingyuan Deng
- Division of Biomedical Informatics, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH, USA
| | - Guo-Chang Fan
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Roger J Hajjar
- Cardiovascular Research Center, Mount Sinai School of Medicine, New York, NY, USA
| | - Evangelia G Kranias
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.,Molecular Biology Division, Center for Basic Research, Foundation for Biomedical Research of the Academy of Athens, Athens, Greece
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Liu GS, Morales A, Vafiadaki E, Lam CK, Cai WF, Haghighi K, Adly G, Hershberger RE, Kranias EG. A novel human R25C-phospholamban mutation is associated with super-inhibition of calcium cycling and ventricular arrhythmia. Cardiovasc Res 2015; 107:164-74. [PMID: 25852082 DOI: 10.1093/cvr/cvv127] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 03/20/2015] [Indexed: 12/26/2022] Open
Abstract
AIMS Depressed sarcoplasmic reticulum (SR) Ca(2+) cycling, a universal characteristic of human and experimental heart failure, may be associated with genetic alterations in key Ca(2+)-handling proteins. In this study, we identified a novel PLN mutation (R25C) in dilated cardiomyopathy (DCM) and investigated its functional significance in cardiomyocyte Ca(2+)-handling and contractility. METHODS AND RESULTS Exome sequencing identified a C73T substitution in the coding region of PLN in a family with DCM. The four heterozygous family members had implantable cardiac defibrillators, and three developed prominent ventricular arrhythmias. Overexpression of R25C-PLN in adult rat cardiomyocytes significantly suppressed the Ca(2+) affinity of SR Ca(2+)-ATPase (SERCA2a), resulting in decreased SR Ca(2+) content, Ca(2+) transients, and impaired contractile function, compared with WT-PLN. These inhibitory effects were associated with enhanced interaction of R25C-PLN with SERCA2, which was prevented by PKA phosphorylation. Accordingly, isoproterenol stimulation relieved the depressive effects of R25C-PLN in cardiomyocytes. However, R25C-PLN also elicited increases in the frequency of Ca(2+) sparks and waves as well as stress-induced aftercontractions. This was accompanied by increased Ca(2+)/calmodulin-dependent protein kinase II activity and hyper-phosphorylation of RyR2 at serine 2814. CONCLUSION The findings demonstrate that human R25C-PLN is associated with super-inhibition of SERCA2a and Ca(2+) transport as well as increased SR Ca(2+) leak, promoting arrhythmogenesis under stress conditions. This is the first mechanistic evidence that increased PLN inhibition may impact both SR Ca(2+) uptake and Ca(2+) release activities and suggests that the human R25C-PLN may be a prognostic factor for increased ventricular arrhythmia risk in DCM carriers.
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Affiliation(s)
- Guan-Sheng Liu
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, PO Box 670575, 231 Albert Sabin Way, Cincinnati, OH, USA
| | - Ana Morales
- Division of Human Genetics, Ohio State University College of Medicine, Columbus, OH, USA Dorothy M. Davis Heart and Lung Research Institute, Ohio State University College of Medicine, Columbus, OH 45267-0575, USA
| | - Elizabeth Vafiadaki
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Greece
| | - Chi Keung Lam
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, PO Box 670575, 231 Albert Sabin Way, Cincinnati, OH, USA
| | - Wen-Feng Cai
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Kobra Haghighi
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, PO Box 670575, 231 Albert Sabin Way, Cincinnati, OH, USA
| | - George Adly
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, PO Box 670575, 231 Albert Sabin Way, Cincinnati, OH, USA
| | - Ray E Hershberger
- Division of Human Genetics, Ohio State University College of Medicine, Columbus, OH, USA Dorothy M. Davis Heart and Lung Research Institute, Ohio State University College of Medicine, Columbus, OH 45267-0575, USA Division of Cardiovascular Medicine, Department of Internal Medicine, Ohio State University College of Medicine, Columbus, OH, USA
| | - Evangelia G Kranias
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, PO Box 670575, 231 Albert Sabin Way, Cincinnati, OH, USA Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Greece
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Sirenko S, Maltsev VA, Maltseva LA, Yang D, Lukyanenko Y, Vinogradova TM, Jones LR, Lakatta EG. Sarcoplasmic reticulum Ca2+ cycling protein phosphorylation in a physiologic Ca2+ milieu unleashes a high-power, rhythmic Ca2+ clock in ventricular myocytes: relevance to arrhythmias and bio-pacemaker design. J Mol Cell Cardiol 2013; 66:106-15. [PMID: 24274954 DOI: 10.1016/j.yjmcc.2013.11.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 11/07/2013] [Accepted: 11/14/2013] [Indexed: 10/26/2022]
Abstract
Basal phosphorylation of sarcoplasmic reticulum (SR) Ca(2+) proteins is high in sinoatrial nodal cells (SANC), which generate partially synchronized, spontaneous, rhythmic, diastolic local Ca(2+) releases (LCRs), but low in ventricular myocytes (VM), which exhibit rare diastolic, stochastic SR-generated Ca(2+) sparks. We tested the hypothesis that in a physiologic Ca(2+) milieu, and independent of increased Ca(2+) influx, an increase in basal phosphorylation of SR Ca(2+) cycling proteins will convert stochastic Ca(2+) sparks into periodic, high-power Ca(2+) signals of the type that drives SANC normal automaticity. We measured phosphorylation of SR-associated proteins, phospholamban (PLB) and ryanodine receptors (RyR), and spontaneous local Ca(2+) release characteristics (LCR) in permeabilized single, rabbit VM in physiologic [Ca(2+)], prior to and during inhibition of protein phosphatase (PP) and phosphodiesterase (PDE), or addition of exogenous cAMP, or in the presence of an antibody (2D12), that specifically inhibits binding of the PLB to SERCA-2. In the absence of the aforementioned perturbations, VM could only generate stochastic local Ca(2+) releases of low power and low amplitude, as assessed by confocal Ca(2+) imaging and spectral analysis. When the kinetics of Ca(2+) pumping into the SR were increased by an increase in PLB phosphorylation (via PDE and PP inhibition or addition of cAMP) or by 2D12, self-organized, "clock-like" local Ca(2+) releases, partially synchronized in space and time (Ca(2+) wavelets), emerged, and the ensemble of these rhythmic local Ca(2+) wavelets generated a periodic high-amplitude Ca(2+) signal. Thus, a Ca(2+) clock is not specific to pacemaker cells, but can also be unleashed in VM when SR Ca(2+) cycling increases and spontaneous local Ca(2+) release becomes partially synchronized. This unleashed Ca(2+) clock that emerges in a physiological Ca(2+) milieu in VM has two faces, however: it can provoke ventricular arrhythmias; or if harnessed, can be an important feature of novel bio-pacemaker designs.
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Affiliation(s)
- Syevda Sirenko
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Victor A Maltsev
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Larissa A Maltseva
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Dongmei Yang
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Yevgeniya Lukyanenko
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Tatiana M Vinogradova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Larry R Jones
- Department of Medicine, Krannert Institute of Cardiology, Indianapolis, IN, USA
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
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