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Aitken‐Buck HM, Khaing EP, Lamberts RR, Jones PP. Study of amphipathic metabolites in cardiac pathophysiology: Insights gained from long-chain acylcarnitines and calcium handling. J Cell Mol Med 2023; 27:3641-3645. [PMID: 37688368 PMCID: PMC10660640 DOI: 10.1111/jcmm.17949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 08/16/2023] [Accepted: 08/30/2023] [Indexed: 09/10/2023] Open
Affiliation(s)
- Hamish M. Aitken‐Buck
- Department of Physiology, HeartOtago, School of Biomedical SciencesUniversity of OtagoDunedinNew Zealand
| | - Ei Phyo Khaing
- Department of Physiology, HeartOtago, School of Biomedical SciencesUniversity of OtagoDunedinNew Zealand
| | - Regis R. Lamberts
- Department of Physiology, HeartOtago, School of Biomedical SciencesUniversity of OtagoDunedinNew Zealand
| | - Peter P. Jones
- Department of Physiology, HeartOtago, School of Biomedical SciencesUniversity of OtagoDunedinNew Zealand
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Okolo CA, Khaing EP, Mereacre V, Wallace RS, Munro ML, Erickson JR, Jones PP. Direct regulation of the cardiac ryanodine receptor (RyR2) by O-GlcNAcylation. Cardiovasc Diabetol 2023; 22:276. [PMID: 37833717 PMCID: PMC10576323 DOI: 10.1186/s12933-023-02010-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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: 05/21/2023] [Accepted: 09/27/2023] [Indexed: 10/15/2023] Open
Abstract
BACKGROUND O-GlcNAcylation is the enzymatic addition of a sugar, O-linked β-N-Acetylglucosamine, to the serine and threonine residues of proteins, and is abundant in diabetic conditions. We have previously shown that O-GlcNAcylation can trigger arrhythmias by indirectly increasing pathological Ca2+ leak through the cardiac ryanodine receptor (RyR2) via Ca2+/calmodulin-dependent kinase II (CaMKII). However, RyR2 is well known to be directly regulated by other forms of serine and threonine modification, therefore, this study aimed to determine whether RyR2 is directly modified by O-GlcNAcylation and if this also alters the function of RyR2 and Ca2+ leak. METHODS O-GlcNAcylation of RyR2 in diabetic human and animal hearts was determined using western blotting. O-GlcNAcylation of RyR2 was pharmacologically controlled and the propensity for Ca2+ leak was determined using single cell imaging. The site of O-GlcNAcylation within RyR2 was determined using site-directed mutagenesis of RyR2. RESULTS We found that RyR2 is modified by O-GlcNAcylation in human, animal and HEK293 cell models. Under hyperglycaemic conditions O-GlcNAcylation was associated with an increase in Ca2+ leak through RyR2 which persisted after CaMKII inhibition. Conversion of serine-2808 to alanine prevented an O-GlcNAcylation induced increase in Ca2+ leak. CONCLUSIONS These data suggest that the function of RyR2 can be directly regulated by O-GlcNAcylation and requires the presence of serine-2808.
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Affiliation(s)
- Chidinma A Okolo
- Department of Physiology, School of Biomedical Sciences, Division of Health Sciences, and HeartOtago, University of Otago, Dunedin, Otago, New Zealand
- Beamline B24, Life Sciences Division, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, England, United Kingdom
| | - Ei-Phyo Khaing
- Department of Physiology, School of Biomedical Sciences, Division of Health Sciences, and HeartOtago, University of Otago, Dunedin, Otago, New Zealand
| | - Valeria Mereacre
- Department of Physiology, School of Biomedical Sciences, Division of Health Sciences, and HeartOtago, University of Otago, Dunedin, Otago, New Zealand
| | - Rachel S Wallace
- Department of Physiology, School of Biomedical Sciences, Division of Health Sciences, and HeartOtago, University of Otago, Dunedin, Otago, New Zealand
| | - Michelle L Munro
- Department of Physiology, School of Biomedical Sciences, Division of Health Sciences, and HeartOtago, University of Otago, Dunedin, Otago, New Zealand
| | - Jeffrey R Erickson
- Department of Physiology, School of Biomedical Sciences, Division of Health Sciences, and HeartOtago, University of Otago, Dunedin, Otago, New Zealand
| | - Peter P Jones
- Department of Physiology, School of Biomedical Sciences, Division of Health Sciences, and HeartOtago, University of Otago, Dunedin, Otago, New Zealand.
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Perdreau-Dahl H, Lipsett DB, Frisk M, Kermani F, Carlson CR, Brech A, Shen X, Bergan-Dahl A, Hou Y, Tuomainen T, Tavi P, Jones PP, Lunde M, Wasserstrom JA, Laporte J, Ullrich ND, Christensen G, Morth JP, Louch WE. BIN1, Myotubularin, and Dynamin-2 Coordinate T-Tubule Growth in Cardiomyocytes. Circ Res 2023; 132:e188-e205. [PMID: 37139790 DOI: 10.1161/circresaha.122.321732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
BACKGROUND Transverse tubules (t-tubules) form gradually in the developing heart, critically enabling maturation of cardiomyocyte Ca2+ homeostasis. The membrane bending and scaffolding protein BIN1 (amphiphysin-2) has been implicated in this process. However, it is unclear which of the various reported BIN1 isoforms are involved, and whether BIN1 function is regulated by its putative binding partners MTM1 (myotubularin), a phosphoinositide 3'-phosphatase, and DNM2 (dynamin-2), a GTPase believed to mediate membrane fission. METHODS We investigated the roles of BIN1, MTM1, and DNM2 in t-tubule formation in developing mouse cardiomyocytes, and in gene-modified HL-1 and human-induced pluripotent stem cell-derived cardiomyocytes. T-tubules and proteins of interest were imaged by confocal and Airyscan microscopy, and expression patterns were examined by RT-qPCR and Western blotting. Ca2+ release was recorded using Fluo-4. RESULTS We observed that in the postnatal mouse heart, BIN1 localizes along Z-lines from early developmental stages, consistent with roles in initial budding and scaffolding of t-tubules. T-tubule proliferation and organization were linked to a progressive and parallel increase in 4 detected BIN1 isoforms. All isoforms were observed to induce tubulation in cardiomyocytes but produced t-tubules with differing geometries. BIN1-induced tubulations contained the L-type Ca2+ channel, were colocalized with caveolin-3 and the ryanodine receptor, and effectively triggered Ca2+ release. BIN1 upregulation during development was paralleled by increasing expression of MTM1. Despite no direct binding between MTM1 and murine cardiac BIN1 isoforms, which lack exon 11, high MTM1 levels were necessary for BIN1-induced tubulation, indicating a central role of phosphoinositide homeostasis. In contrast, the developing heart exhibited declining levels of DNM2. Indeed, we observed that high levels of DNM2 are inhibitory for t-tubule formation, although this protein colocalizes with BIN1 along Z-lines, and binds all 4 isoforms. CONCLUSIONS These findings indicate that BIN1, MTM1, and DNM2 have balanced and collaborative roles in controlling t-tubule growth in cardiomyocytes.
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Affiliation(s)
- Harmonie Perdreau-Dahl
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital and University of Oslo, Norway (H.P.-D., D.B.L., M.F., C.R.C., X.S., A.B.-D., Y.H., M.L., G.C., J.P.M., W.E.L.)
- KG Jebsen Center for Cardiac Research, University of Oslo, Norway (H.P.-D., D.B.L., M.F., X.S., A.B.-D., Y.H., M.L., G.C., W.E.L.)
- Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership University of Oslo, Norway (H.P.-D., J.P.M.)
- Institut MitoVasc, CNRS UMR 6015, INSERM U1083, Université d'Angers, France (H.P.-D.)
| | - David B Lipsett
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital and University of Oslo, Norway (H.P.-D., D.B.L., M.F., C.R.C., X.S., A.B.-D., Y.H., M.L., G.C., J.P.M., W.E.L.)
- KG Jebsen Center for Cardiac Research, University of Oslo, Norway (H.P.-D., D.B.L., M.F., X.S., A.B.-D., Y.H., M.L., G.C., W.E.L.)
| | - Michael Frisk
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital and University of Oslo, Norway (H.P.-D., D.B.L., M.F., C.R.C., X.S., A.B.-D., Y.H., M.L., G.C., J.P.M., W.E.L.)
- KG Jebsen Center for Cardiac Research, University of Oslo, Norway (H.P.-D., D.B.L., M.F., X.S., A.B.-D., Y.H., M.L., G.C., W.E.L.)
| | - Fatemeh Kermani
- Division of Cardiovascular Physiology, Institute of Physiology and Pathophysiology, Heidelberg University, Germany (F.K., N.D.U.)
| | - Cathrine R Carlson
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital and University of Oslo, Norway (H.P.-D., D.B.L., M.F., C.R.C., X.S., A.B.-D., Y.H., M.L., G.C., J.P.M., W.E.L.)
| | - Andreas Brech
- Department of Molecular Cell Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, Norway (A.B.)
| | - Xin Shen
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital and University of Oslo, Norway (H.P.-D., D.B.L., M.F., C.R.C., X.S., A.B.-D., Y.H., M.L., G.C., J.P.M., W.E.L.)
- KG Jebsen Center for Cardiac Research, University of Oslo, Norway (H.P.-D., D.B.L., M.F., X.S., A.B.-D., Y.H., M.L., G.C., W.E.L.)
| | - Anna Bergan-Dahl
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital and University of Oslo, Norway (H.P.-D., D.B.L., M.F., C.R.C., X.S., A.B.-D., Y.H., M.L., G.C., J.P.M., W.E.L.)
- KG Jebsen Center for Cardiac Research, University of Oslo, Norway (H.P.-D., D.B.L., M.F., X.S., A.B.-D., Y.H., M.L., G.C., W.E.L.)
| | - Yufeng Hou
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital and University of Oslo, Norway (H.P.-D., D.B.L., M.F., C.R.C., X.S., A.B.-D., Y.H., M.L., G.C., J.P.M., W.E.L.)
- KG Jebsen Center for Cardiac Research, University of Oslo, Norway (H.P.-D., D.B.L., M.F., X.S., A.B.-D., Y.H., M.L., G.C., W.E.L.)
| | - Tomi Tuomainen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland (T.T., P.T.)
| | - Pasi Tavi
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland (T.T., P.T.)
| | - Peter P Jones
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand (P.P.J.)
| | - Marianne Lunde
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital and University of Oslo, Norway (H.P.-D., D.B.L., M.F., C.R.C., X.S., A.B.-D., Y.H., M.L., G.C., J.P.M., W.E.L.)
- KG Jebsen Center for Cardiac Research, University of Oslo, Norway (H.P.-D., D.B.L., M.F., X.S., A.B.-D., Y.H., M.L., G.C., W.E.L.)
| | | | - Jocelyn Laporte
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U1258, CNRS UMR7104, Strasbourg University, Illkirch, France (J.L.)
| | - Nina D Ullrich
- Division of Cardiovascular Physiology, Institute of Physiology and Pathophysiology, Heidelberg University, Germany (F.K., N.D.U.)
- German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Germany (N.D.U.)
| | - Geir Christensen
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital and University of Oslo, Norway (H.P.-D., D.B.L., M.F., C.R.C., X.S., A.B.-D., Y.H., M.L., G.C., J.P.M., W.E.L.)
- KG Jebsen Center for Cardiac Research, University of Oslo, Norway (H.P.-D., D.B.L., M.F., X.S., A.B.-D., Y.H., M.L., G.C., W.E.L.)
| | - J Preben Morth
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital and University of Oslo, Norway (H.P.-D., D.B.L., M.F., C.R.C., X.S., A.B.-D., Y.H., M.L., G.C., J.P.M., W.E.L.)
- Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership University of Oslo, Norway (H.P.-D., J.P.M.)
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark (J.P.M.)
| | - William E Louch
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital and University of Oslo, Norway (H.P.-D., D.B.L., M.F., C.R.C., X.S., A.B.-D., Y.H., M.L., G.C., J.P.M., W.E.L.)
- KG Jebsen Center for Cardiac Research, University of Oslo, Norway (H.P.-D., D.B.L., M.F., X.S., A.B.-D., Y.H., M.L., G.C., W.E.L.)
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Ohline SM, Liu X, Ibrahim MF, Mockett BM, Empson RM, Abraham WC, Iremonger KJ, Jones PP. Altered membrane properties but unchanged intrinsic excitability and spontaneous postsynaptic currents in an aged APPswe/PS1dE9 model of Alzheimer’s disease. Front Cell Neurosci 2022; 16:958876. [PMID: 36090787 PMCID: PMC9459330 DOI: 10.3389/fncel.2022.958876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 08/09/2022] [Indexed: 11/13/2022] Open
Abstract
Neuronal hyperexcitability in Alzheimer’s disease (AD) models is thought to either contribute to the formation of amyloid beta plaques or result from their formation. Neuronal hyperexcitability has been shown in the cerebral cortex of the widely used young APPswe/PS1dE9 mice, which have accelerated plaque formation. However, it is currently unclear if hyperexcitability also occurs in CA1 hippocampal neurons of aged animals in this model. In the present work, we have compared intrinsic excitability and spontaneous synaptic inputs from CA1 pyramidal cells of 8-month-old APPswe/PS1dE9 and wildtype control mice. We find no change in intrinsic excitability or spontaneous postsynaptic currents (PSCs) between groups. We did, however, find a reduced input resistance and an increase in hyperpolarization-activated sag current. These results are consistent with findings from other aged AD model mice, including the widely used 5xFAD and 3xTg. Together these results suggest that neuronal hyperexcitability is not a consistent feature of all AD mouse models, particularly at advanced ages.
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Affiliation(s)
- Shane M. Ohline
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- HeartOtago, University of Otago, Dunedin, New Zealand
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- *Correspondence: Shane M. Ohline,
| | - Xinhuai Liu
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Mohamed F. Ibrahim
- Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, United Kingdom
| | - Bruce M. Mockett
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Department of Psychology, University of Otago, Dunedin, New Zealand
| | - Ruth M. Empson
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Wickliffe C. Abraham
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Department of Psychology, University of Otago, Dunedin, New Zealand
| | - Karl J. Iremonger
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Peter P. Jones
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- HeartOtago, University of Otago, Dunedin, New Zealand
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Peter P. Jones,
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Satthenapalli R, Lee S, Bellae Papannarao J, Hore TA, Chakraborty A, Jones PP, Lamberts RR, Katare R. Stage-specific regulation of signalling pathways to differentiate pluripotent stem cells to cardiomyocytes with ventricular lineage. Stem Cell Res Ther 2022; 13:185. [PMID: 35524336 PMCID: PMC9077927 DOI: 10.1186/s13287-022-02845-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 04/11/2022] [Indexed: 11/18/2022] Open
Abstract
Background Pluripotent stem cells (PSCs) can be an ideal source of differentiation of cardiomyocytes in vitro and during transplantation to induce cardiac regeneration. However, differentiation of PSCs into a heterogeneous population is associated with an increased incidence of arrhythmia following transplantation. We aimed to design a protocol to drive PSCs to a ventricular lineage by regulating Wnt and retinoic acid (RA) signalling pathways. Methods Mouse embryonic stem cells were cultured either in monolayers or three-dimensional hanging drop method to form embryonic bodies (EBs) and exposed to different treatments acting on Wnt and retinoic acid signalling. Samples were collected at different time points to analyse cardiomyocyte-specific markers by RT-PCR, flow cytometry and immunofluorescence. Results Treatment of monolayer and EBs with Wnt and RA signalling pathways and ascorbic acid, as a cardiac programming enhancer, resulted in the formation of an immature non-contractile cardiac population that expressed many of the putative markers of cardiac differentiation. The population exhibited upregulation of ventricular specific markers while suppressing the expression of pro-atrial and pro-sinoatrial markers. Differentiation of EBs resulted in early foetal like non-contractile ventricular cardiomyocytes with an inherent propensity to contract when stimulated. Conclusion Our results provide the first evidence of in vitro differentiation that mimics the embryonic morphogenesis towards ventricular specific cardiomyocytes through regulation of Wnt and RA signalling pathways. Supplementary Information The online version contains supplementary material available at 10.1186/s13287-022-02845-9.
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Affiliation(s)
- Ramakanth Satthenapalli
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, 270, Great King Street, Dunedin, 9010, New Zealand
| | - Scott Lee
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, 270, Great King Street, Dunedin, 9010, New Zealand
| | - Jayanthi Bellae Papannarao
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, 270, Great King Street, Dunedin, 9010, New Zealand
| | - Timothy A Hore
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, 9010, New Zealand
| | - Akash Chakraborty
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, 270, Great King Street, Dunedin, 9010, New Zealand.,Oklahoma Medical Research Foundation, Oklahoma City, USA
| | - Peter P Jones
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, 270, Great King Street, Dunedin, 9010, New Zealand
| | - Regis R Lamberts
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, 270, Great King Street, Dunedin, 9010, New Zealand
| | - Rajesh Katare
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, 270, Great King Street, Dunedin, 9010, New Zealand.
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Ng YH, Okolo CA, Erickson JR, Baldi JC, Jones PP. Protein O-GlcNAcylation in the heart. Acta Physiol (Oxf) 2021; 233:e13696. [PMID: 34057811 DOI: 10.1111/apha.13696] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/25/2021] [Accepted: 05/27/2021] [Indexed: 12/30/2022]
Abstract
O-GlcNAcylation is a ubiquitous post-translational modification that is extremely labile and plays a significant role in physiology, including the heart. Sustained activation of cardiac O-GlcNAcylation is frequently associated with alterations in cellular metabolism, leading to detrimental effects on cardiovascular function. This is particularly true during conditions such as diabetes, hypertension, cardiac remodelling, heart failure and arrhythmogenesis. Paradoxically, transient elevation of cardiac protein O-GlcNAcylation can also exert beneficial effects in the heart. There is compelling evidence to suggest that a complex interaction between O-GlcNAcylation and phosphorylation also exists in the heart. Beyond direct functional consequences on cardiomyocytes, O-GlcNAcylation also acts indirectly by altering the function of transcription factors that affect downstream signalling. This review focuses on the potential cardioprotective role of protein O-GlcNAcylation during ischaemia-reperfusion injury, the deleterious consequences of chronically elevated O-GlcNAc levels, the interplay between O-GlcNAcylation and phosphorylation in the cardiomyocytes and the effects of O-GlcNAcylation on other major non-myocyte cell types in the heart.
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Affiliation(s)
- Yann Huey Ng
- Department of Medicine and HeartOtago University of Otago Dunedin New Zealand
| | - Chidinma A. Okolo
- Department of Physiology and HeartOtago University of Otago Dunedin New Zealand
- Life Sciences Division Diamond Light Source LtdHarwell Science and Innovation Campus Didcot UK
| | - Jeffrey R. Erickson
- Department of Physiology and HeartOtago University of Otago Dunedin New Zealand
| | - James C. Baldi
- Department of Medicine and HeartOtago University of Otago Dunedin New Zealand
| | - Peter P. Jones
- Department of Physiology and HeartOtago University of Otago Dunedin New Zealand
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7
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Frisk M, Le C, Shen X, Røe ÅT, Hou Y, Manfra O, Silva GJJ, van Hout I, Norden ES, Aronsen JM, Laasmaa M, Espe EKS, Zouein FA, Lambert RR, Dahl CP, Sjaastad I, Lunde IG, Coffey S, Cataliotti A, Gullestad L, Tønnessen T, Jones PP, Altara R, Louch WE. Etiology-Dependent Impairment of Diastolic Cardiomyocyte Calcium Homeostasis in Heart Failure With Preserved Ejection Fraction. J Am Coll Cardiol 2021; 77:405-419. [PMID: 33509397 PMCID: PMC7840890 DOI: 10.1016/j.jacc.2020.11.044] [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] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/26/2020] [Accepted: 11/16/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Whereas heart failure with reduced ejection fraction (HFrEF) is associated with ventricular dilation and markedly reduced systolic function, heart failure with preserved ejection fraction (HFpEF) patients exhibit concentric hypertrophy and diastolic dysfunction. Impaired cardiomyocyte Ca2+ homeostasis in HFrEF has been linked to disruption of membrane invaginations called t-tubules, but it is unknown if such changes occur in HFpEF. OBJECTIVES This study examined whether distinct cardiomyocyte phenotypes underlie the heart failure entities of HFrEF and HFpEF. METHODS T-tubule structure was investigated in left ventricular biopsies obtained from HFrEF and HFpEF patients, whereas cardiomyocyte Ca2+ homeostasis was studied in rat models of these conditions. RESULTS HFpEF patients exhibited increased t-tubule density in comparison with control subjects. Super-resolution imaging revealed that higher t-tubule density resulted from both tubule dilation and proliferation. In contrast, t-tubule density was reduced in patients with HFrEF. Augmented collagen deposition within t-tubules was observed in HFrEF but not HFpEF hearts. A causative link between mechanical stress and t-tubule disruption was supported by markedly elevated ventricular wall stress in HFrEF patients. In HFrEF rats, t-tubule loss was linked to impaired systolic Ca2+ homeostasis, although diastolic Ca2+ removal was also reduced. In contrast, Ca2+ transient magnitude and release kinetics were largely maintained in HFpEF rats. However, diastolic Ca2+ impairments, including reduced sarco/endoplasmic reticulum Ca2+-ATPase activity, were specifically observed in diabetic HFpEF but not in ischemic or hypertensive models. CONCLUSIONS Although t-tubule disruption and impaired cardiomyocyte Ca2+ release are hallmarks of HFrEF, such changes are not prominent in HFpEF. Impaired diastolic Ca2+ homeostasis occurs in both conditions, but in HFpEF, this mechanism for diastolic dysfunction is etiology-dependent.
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Affiliation(s)
- Michael Frisk
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway. https://twitter.com/IEMRLouch
| | - Christopher Le
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Xin Shen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Åsmund T Røe
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Yufeng Hou
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Ornella Manfra
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Gustavo J J Silva
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Isabelle van Hout
- Department of Physiology, HeartOtago, University of Otago, Otago, New Zealand
| | - Einar S Norden
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway; Bjørknes College, Oslo, Norway
| | - J Magnus Aronsen
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Martin Laasmaa
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Emil K S Espe
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Fouad A Zouein
- Department of Pharmacology and Toxicology, American University of Beirut Medical Center, Faculty of Medicine, Riad El-Solh, Beirut, Lebanon
| | - Regis R Lambert
- Department of Physiology, HeartOtago, University of Otago, Otago, New Zealand
| | - Christen P Dahl
- Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway; Research Institute for Internal Medicine, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway; Department of Cardiology, Oslo University Hospital, Ullevål, Oslo, Norway
| | - Ida G Lunde
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Sean Coffey
- Department of Medicine and HeartOtago, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Alessandro Cataliotti
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Lars Gullestad
- Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway; Research Institute for Internal Medicine, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Theis Tønnessen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway; Department of Cardiothoracic Surgery, Oslo University Hospital Ullevål, Oslo, Norway
| | - Peter P Jones
- Department of Physiology, HeartOtago, University of Otago, Otago, New Zealand
| | - Raffaele Altara
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway. https://twitter.com/IEMRLouch
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
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8
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Aitken-Buck HM, Krause J, van Hout I, Davis PJ, Bunton RW, Parry DJ, Williams MJA, Coffey S, Zeller T, Jones PP, Lamberts RR. Long-chain acylcarnitine 18:1 acutely increases human atrial myocardial contractility and arrhythmia susceptibility. Am J Physiol Heart Circ Physiol 2021; 321:H162-H174. [PMID: 34085842 DOI: 10.1152/ajpheart.00184.2021] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Long-chain acylcarnitines (LCACs) are known to directly alter cardiac contractility and electrophysiology. However, the acute effect of LCACs on human cardiac function is unknown. We aimed to determine the effect of LCAC 18:1, which has been associated with cardiovascular disease, on the contractility and arrhythmia susceptibility of human atrial myocardium. Additionally, we aimed to assess how LCAC 18:1 alters Ca2+ influx and spontaneous Ca2+ release in vitro. Human right atrial trabeculae (n = 32) stimulated at 1 Hz were treated with LCAC 18:1 at a range of concentrations (1-25 µM) for a 45-min period. Exposure to the LCAC induced a dose-dependent positive inotropic effect on myocardial contractility (maximal 1.5-fold increase vs. control). At the 25 µM dose (n = 8), this was paralleled by an enhanced propensity for spontaneous contractions (50% increase). Furthermore, all LCAC 18:1 effects on myocardial function were reversed following LCAC 18:1 washout. In fluo-4-AM-loaded HEK293 cells, LCAC 18:1 dose dependently increased cytosolic Ca2+ influx relative to vehicle controls and the short-chain acylcarnitine C3. In HEK293 cells expressing ryanodine receptor (RyR2), this increased Ca2+ influx was linked to an increased propensity for RyR2-mediated spontaneous Ca2+ release events. Our study is the first to show that LCAC 18:1 directly and acutely alters human myocardial function and in vitro Ca2+ handling. The metabolite promotes proarrhythmic muscle contractions and increases contractility. The exploratory findings in vitro suggest that LCAC 18:1 increases proarrhythmic RyR2-mediated spontaneous Ca2+ release propensity. The direct effects of metabolites on human myocardial function are essential to understand cardiometabolic dysfunction.NEW & NOTEWORTHY For the first time, the fatty acid metabolite, long-chain acylcarnitine 18:1, is shown to acutely increase the arrhythmia susceptibility and contractility of human atrial myocardium. In vitro, this was linked to an influx of Ca2+ and an enhanced propensity for spontaneous RyR2-mediated Ca2+ release.
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Affiliation(s)
- Hamish M Aitken-Buck
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Julia Krause
- University Heart and Vascular Centre, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Isabelle van Hout
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Philip J Davis
- Department of Cardiothoracic Surgery, Otago Medical School-Dunedin Campus, Dunedin Hospital, Dunedin, New Zealand
| | - Richard W Bunton
- Department of Cardiothoracic Surgery, Otago Medical School-Dunedin Campus, Dunedin Hospital, Dunedin, New Zealand
| | - Dominic J Parry
- Department of Cardiothoracic Surgery, Otago Medical School-Dunedin Campus, Dunedin Hospital, Dunedin, New Zealand
| | - Michael J A Williams
- Department of Medicine, Heart Otago, Otago Medical School-Dunedin Campus, University of Otago, Dunedin, New Zealand
| | - Sean Coffey
- Department of Medicine, Heart Otago, Otago Medical School-Dunedin Campus, University of Otago, Dunedin, New Zealand
| | - Tanja Zeller
- University Heart and Vascular Centre, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Peter P Jones
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Regis R Lamberts
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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9
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Munro ML, van Hout I, Aitken-Buck HM, Sugunesegran R, Bhagwat K, Davis PJ, Lamberts RR, Coffey S, Soeller C, Jones PP. Human Atrial Fibrillation Is Not Associated With Remodeling of Ryanodine Receptor Clusters. Front Cell Dev Biol 2021; 9:633704. [PMID: 33718369 PMCID: PMC7947344 DOI: 10.3389/fcell.2021.633704] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 11/26/2020] [Accepted: 02/08/2021] [Indexed: 12/02/2022] Open
Abstract
The release of Ca2+ by ryanodine receptor (RyR2) channels is critical for cardiac function. However, abnormal RyR2 activity has been linked to the development of arrhythmias, including increased spontaneous Ca2+ release in human atrial fibrillation (AF). Clustering properties of RyR2 have been suggested to alter the activity of the channel, with remodeling of RyR2 clusters identified in pre-clinical models of AF and heart failure. Whether such remodeling occurs in human cardiac disease remains unclear. This study aimed to investigate the nanoscale organization of RyR2 clusters in AF patients – the first known study to examine this potential remodeling in diseased human cardiomyocytes. Right atrial appendage from cardiac surgery patients with paroxysmal or persistent AF, or without AF (non-AF) were examined using super-resolution (dSTORM) imaging. Significant atrial dilation and cardiomyocyte hypertrophy was observed in persistent AF patients compared to non-AF, with these two parameters significantly correlated. Interestingly, the clustering properties of RyR2 were remarkably unaltered in the AF patients. No significant differences were identified in cluster size (mean ∼18 RyR2 channels), density or channel packing within clusters between patient groups. The spatial organization of clusters throughout the cardiomyocyte was also unchanged across the groups. RyR2 clustering properties did not significantly correlate with patient characteristics. In this first study to examine nanoscale RyR2 organization in human cardiac disease, these findings indicate that RyR2 cluster remodeling is not an underlying mechanism contributing to altered channel function and subsequent arrhythmogenesis in human AF.
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Affiliation(s)
- Michelle L Munro
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Isabelle van Hout
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Hamish M Aitken-Buck
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | | | - Krishna Bhagwat
- Department of Cardiothoracic Surgery, Dunedin Hospital, Dunedin, New Zealand
| | - Philip J Davis
- Department of Cardiothoracic Surgery, Dunedin Hospital, Dunedin, New Zealand
| | - Regis R Lamberts
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Sean Coffey
- Department of Medicine and HeartOtago, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Christian Soeller
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | - Peter P Jones
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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10
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Aitken-Buck HM, Krause J, Zeller T, Jones PP, Lamberts RR. Long-Chain Acylcarnitines and Cardiac Excitation-Contraction Coupling: Links to Arrhythmias. Front Physiol 2020; 11:577856. [PMID: 33041874 PMCID: PMC7518131 DOI: 10.3389/fphys.2020.577856] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [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: 07/01/2020] [Accepted: 08/25/2020] [Indexed: 12/31/2022] Open
Abstract
A growing number of metabolomic studies have associated high circulating levels of the amphiphilic fatty acid metabolites, long-chain acylcarnitines (LCACs), with cardiovascular disease (CVD) risk. These studies show that plasma LCAC levels can be correlated with the stage and severity of CVD and with indices of cardiac hypertrophy and ventricular function. Complementing these recent clinical associations is an extensive body of basic research that stems mostly from the twentieth century. These works, performed in cardiomyocyte and multicellular preparations from animal and cell models, highlight stereotypical derangements in cardiac electrophysiology induced by exogenous LCAC treatment that promote arrhythmic muscle behavior. In many cases, this is coupled with acute inotropic modulation; however, whether LCACs increase or decrease contractility is inconclusive. Linked to the electromechanical alterations induced by LCAC exposure is an array of effects on cardiac excitation-contraction coupling mechanisms that overload the cardiomyocyte cytosol with Na+ and Ca2+ ions. The aim of this review is to revisit this age-old literature and collate it with recent findings to provide a pathophysiological context for the growing body of metabolomic association studies that link circulating LCACs with CVD.
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Affiliation(s)
- Hamish M Aitken-Buck
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Julia Krause
- University Heart and Vascular Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Hamburg, Hamburg, Germany
| | - Tanja Zeller
- University Heart and Vascular Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Hamburg, Hamburg, Germany
| | - Peter P Jones
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Regis R Lamberts
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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11
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Aitken-Buck HM, Babakr AA, Fomison-Nurse IC, van Hout I, Davis PJ, Bunton RW, Williams MJA, Coffey S, Jones PP, Lamberts RR. Inotropic and lusitropic, but not arrhythmogenic, effects of adipocytokine resistin on human atrial myocardium. Am J Physiol Endocrinol Metab 2020; 319:E540-E547. [PMID: 32715745 DOI: 10.1152/ajpendo.00202.2020] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The adipocytokine resistin is released from epicardial adipose tissue (EAT). Plasma resistin and EAT deposition are independently associated with atrial fibrillation. The EAT secretome enhances arrhythmia susceptibility and inotropy of human myocardium. Therefore, we aimed to determine the effect of resistin on the function of human myocardium and how resistin contributes to the proarrhythmic effect of EAT. EAT biopsies were obtained from 25 cardiac surgery patients. Resistin levels were measured by ELISA in 24-h EAT culture media (n = 8). The secretome resistin concentrations increased over the culture period to a maximal level of 5.9 ± 1.2 ng/mL. Coculture with β-adrenergic agonists isoproterenol (n = 4) and BRL37344 (n = 13) had no effect on EAT resistin release. Addition of resistin (7, 12, 20 ng/mL) did not significantly increase the spontaneous contraction propensity of human atrial trabeculae (n = 10) when given alone or in combination with isoproterenol. Resistin dose-dependently increased trabecula-developed force (maximal 2.9-fold increase, P < 0.0001), as well as the maximal rates of contraction (2.6-fold increase, P = 0.002) and relaxation (1.8-fold increase, P = 0.007). Additionally, the postrest potentiation capacity of human trabeculae was reduced at all resistin doses, suggesting that the inotropic effect induced by resistin might be due to altered sarcoplasmic reticulum Ca2+ handling. EAT resistin release is not modulated by common arrhythmia triggers. Furthermore, exogenous resistin does not promote arrhythmic behavior in human atrial trabeculae. Resistin does, however, induce an acute dose-dependent positive inotropic and lusitropic effect.
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Affiliation(s)
- Hamish M Aitken-Buck
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Aram A Babakr
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Ingrid C Fomison-Nurse
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Isabelle van Hout
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Philip J Davis
- Department of Cardiothoracic Surgery, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Richard W Bunton
- Department of Cardiothoracic Surgery, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Michael J A Williams
- Department of Medicine and HeartOtago, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Sean Coffey
- Department of Medicine and HeartOtago, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Peter P Jones
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Regis R Lamberts
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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12
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Moharram MA, Aitken-Buck HM, Reijers R, Hout IV, Williams MJ, Jones PP, Whalley GA, Lamberts RR, Coffey S. Correlation between epicardial adipose tissue and body mass index in New Zealand ethnic populations. N Z Med J 2020; 133:22-32. [PMID: 32525859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
AIM We aimed to investigate the correlation between epicardial adipose tissue (EAT) and body mass index (BMI) in different ethnic groups in New Zealand. METHODS The study included 205 individuals undergoing open heart surgery. Māori and Pacific groups were combined to increase statistical power. EAT was measured using 2D echocardiography. RESULTS There were 164 New Zealand Europeans (NZE) and 41 Māori/Pacific participants. The mean (SD) age of the study group was 67.9 (10.1) years, 69.1 (9.5) for NZE and 63.5 (11.4) for Māori/Pacific. BMI was 29.6 (5.5) kg/m2 for NZE and 31.8 (6.2) for Māori/Pacific. EAT thickness was 6.2 (2.2) mm and 6.0 (1.8) mm for NZE and Māori/Pacific, respectively. Using univariate linear regression, BMI showed moderate correlation with EAT in NZE (R2=0.26, p<0.001); however, there was no significant correlation between BMI and EAT in Māori/Pacific patients (R2=0.05, p=0.17). Using multivariate analysis, BMI remained a significant predictor of EAT thickness in NZE (R2 =0.27, p<0.001). CONCLUSIONS BMI was associated with EAT thickness in NZE patients, but not in Māori/Pacific patients. The same level of BMI can carry different connotations of risk in different ethnic groups, with BMI likely being an inconsistent measure of obesity in in Māori/Pacific patients.
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Affiliation(s)
- Mohammed A Moharram
- Department of Medicine, HeartOtago, Dunedin School of Medicine, University of Otago, Dunedin
| | - Hamish M Aitken-Buck
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin
| | - Robin Reijers
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin
| | - Isabelle van Hout
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin
| | - Michael Ja Williams
- Department of Medicine, HeartOtago, Dunedin School of Medicine, University of Otago, Dunedin
| | - Peter P Jones
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin
| | - Gillian A Whalley
- Department of Medicine, HeartOtago, Dunedin School of Medicine, University of Otago, Dunedin
| | - Regis R Lamberts
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin
| | - Sean Coffey
- Department of Medicine, HeartOtago, Dunedin School of Medicine, University of Otago, Dunedin
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13
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McNeill SM, Giles NM, Preston D, Jones PP, Crowley JD, Giles GI. Quadruply Stranded Metallo-Supramolecular Helicate [Pd 2(hextrz) 4] 4+ Acts as a Molecular Mimic of Cytolytic Peptides. Chem Res Toxicol 2020; 33:1822-1834. [PMID: 32347099 DOI: 10.1021/acs.chemrestox.0c00061] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
[Pd2(hextrz)4]4+ is a quadruply stranded helicate, a novel bioinorganic complex designed to mimic the structure and function of proteins due to its high stability and supramolecular size. We have previously reported that [Pd2(hextrz)4]4+ exhibited cytotoxicity toward a range of cell lines, with IC50 values ranging from 3 to 10 μM. Here we demonstrate that [Pd2(hextrz)4]4+ kills cells by forming pores within the cell membrane, a mechanism of cell death analogous to the naturally occurring cytolytic peptides. [Pd2(hextrz)4]4+ induced cell death is characterized by an initial influx of Ca2+, followed by nuclear condensation and mitochondrial swelling. This is accompanied by progressive cell membrane damage that results in the formation of large blebs at the cell surface. This allows the efflux of molecules from the cell leading to loss of cell viability. These data suggest that it may be possible to design metallo-supramolecular complexes to mimic the cytotoxic action of pore forming proteins and peptides and so provide a new class of drug to treat cancer, autoimmune disorders, and microbial infection.
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Affiliation(s)
- Samantha M McNeill
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Niroshini M Giles
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Dan Preston
- Department of Chemistry, University of Otago, Dunedin, New Zealand
| | - Peter P Jones
- Department of Physiology and HeartOtago, University of Otago, Dunedin, New Zealand
| | - James D Crowley
- Department of Chemistry, University of Otago, Dunedin, New Zealand
| | - Gregory I Giles
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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14
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Loehfelm A, Elder MK, Boucsein A, Jones PP, Williams JM, Tups A. Docosahexaenoic acid prevents palmitate-induced insulin-dependent impairments of neuronal health. FASEB J 2020; 34:4635-4652. [PMID: 32030816 DOI: 10.1096/fj.201902517r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [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: 10/01/2019] [Revised: 12/19/2019] [Accepted: 01/20/2020] [Indexed: 02/06/2023]
Abstract
The importance of fatty acids (FAs) for healthy brain development and function has become more evident in the past decades. However, most studies focus on the hypothalamus as an important FA-sensing brain region involved in energy homeostasis. Less work has been done to evaluate the effects of FAs on brain regions such as the hippocampus or cortex, two important centres of learning, memory formation, and cognition. Furthermore, the mechanisms of how FAs modulate the neuronal development and function are incompletely understood. Therefore, this study examined the effects of the saturated FA palmitic acid (PA) and the polyunsaturated FA docosahexaenoic acid (DHA) on primary hippocampal and cortical cultures isolated from P0/P1 Sprague Dawley rat pups. Exposure to PA, but not DHA, resulted in severe morphological changes in primary neurons such as cell body swelling, axonal and dendritic blebbing, and a reduction in synaptic innervation, compromising healthy cell function and excitability. Pharmacological assessment revealed that the PA-mediated alterations were caused by overactivation of neuronal insulin signaling, demonstrated by insulin stimulation and phosphoinositide 3-kinase inhibition. Remarkably, co-exposure to DHA prevented all PA-induced morphological changes. This work provides new insights into how FAs can affect the cytoskeletal rearrangements and neuronal function via modulation of insulin signaling.
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Affiliation(s)
- Aline Loehfelm
- Department of Physiology, School of Medical Sciences, Centre for Neuroendocrinology and Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Megan K Elder
- Department of Anatomy, School of Medical Sciences, Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Alisa Boucsein
- Department of Physiology, School of Medical Sciences, Centre for Neuroendocrinology and Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Peter P Jones
- Department of Physiology and HeartOtago, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Joanna M Williams
- Department of Anatomy, School of Medical Sciences, Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Alexander Tups
- Department of Physiology, School of Medical Sciences, Centre for Neuroendocrinology and Brain Health Research Centre, University of Otago, Dunedin, New Zealand
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15
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Babakr AA, Fomison-Nurse IC, van Hout I, Aitken-Buck HM, Sugunesegran R, Davis PJ, Bunton RW, Williams MJA, Coffey S, Stiles MK, Jones PP, Lamberts RR. Acute interaction between human epicardial adipose tissue and human atrial myocardium induces arrhythmic susceptibility. Am J Physiol Endocrinol Metab 2020; 318:E164-E172. [PMID: 31821041 DOI: 10.1152/ajpendo.00374.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Epicardial adipose tissue (EAT) deposition has a strong clinical association with atrial arrhythmias; however, whether a direct functional interaction exists between EAT and the myocardium to induce atrial arrhythmias is unknown. Therefore, we aimed to determine whether human EAT can be an acute trigger for arrhythmias in human atrial myocardium. Human trabeculae were obtained from right atrial appendages of patients who have had cardiac surgery (n = 89). The propensity of spontaneous contractions (SCs) in the trabeculae (proxy for arrhythmias) was determined under physiological conditions and during known triggers of SCs (high Ca2+, β-adrenergic stimulation). To determine whether EAT could trigger SCs, trabeculae were exposed to superfusate of fresh human EAT, and medium of 24 h-cultured human EAT treated with β1/2 (isoproterenol) or β3 (BRL37344) adrenergic agonists. Without exposure to EAT, high Ca2+ and β1/2-adrenergic stimulation acutely triggered SCs in, respectively, 47% and 55% of the trabeculae that previously were not spontaneously active. Acute β3-adrenergic stimulation did not trigger SCs. Exposure of trabeculae to either superfusate of fresh human EAT or untreated medium of 24 h-cultured human EAT did not induce SCs; however, specific β3-adrenergic stimulation of EAT did trigger SCs in the trabeculae, either when applied to fresh (31%) or cultured (50%) EAT. Additionally, fresh EAT increased trabecular contraction and relaxation, whereas media of cultured EAT only increased function when treated with the β3-adrenergic agonist. An acute functional interaction between human EAT and human atrial myocardium exists that increases the propensity for atrial arrhythmias, which depends on β3-adrenergic rather than β1/2-adrenergic stimulation of EAT.
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Affiliation(s)
- Aram A Babakr
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Ingrid C Fomison-Nurse
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Isabelle van Hout
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Hamish M Aitken-Buck
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Ramanen Sugunesegran
- Department of Cardiothoracic Surgery, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Philip J Davis
- Department of Cardiothoracic Surgery, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Richard W Bunton
- Department of Cardiothoracic Surgery, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Michael J A Williams
- Department of Medicine, HeartOtago, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Sean Coffey
- Department of Medicine, HeartOtago, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Martin K Stiles
- Department of Cardiology, Waikato District Health Board, Hamilton, New Zealand
- Waikato Clinical School, University of Auckland, Hamilton, New Zealand
| | - Peter P Jones
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Regis R Lamberts
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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16
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Hou Y, Laasmaa M, Li J, Manfra O, Shen X, Jones PP, Soeller C, Louch WE. Correlating Calcium Sparks and Ryanodine Receptor Localization in Live Cardiomyocytes. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.3088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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17
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Munro ML, Jones PP. Too much of a good thing? Establishing a role of excessive RyR2 dephosphorylation in heart disease. J Physiol 2020; 598:1115-1116. [PMID: 31994730 DOI: 10.1113/jp279569] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 01/27/2020] [Indexed: 01/06/2023] Open
Affiliation(s)
- Michelle L Munro
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Peter P Jones
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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18
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Aitken-Buck HM, Moharram M, Babakr AA, Reijers R, Van Hout I, Fomison-Nurse IC, Sugunesegran R, Bhagwat K, Davis PJ, Bunton RW, Williams MJA, Stiles MK, Jones PP, Coffey S, Lamberts RR. Relationship between epicardial adipose tissue thickness and epicardial adipocyte size with increasing body mass index. Adipocyte 2019; 8:412-420. [PMID: 31829077 PMCID: PMC6948959 DOI: 10.1080/21623945.2019.1701387] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [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] [Indexed: 01/01/2023] Open
Abstract
Macroscopic deposition of epicardial adipose tissue (EAT) has been strongly associated with numerous indices of obesity and cardiovascular disease risk. In contrast, the morphology of EAT adipocytes has rarely been investigated. We aimed to determine whether obesity-driven adipocyte hypertrophy, which is characteristic of other visceral fat depots, is found within EAT adipocytes. EAT samples were collected from cardiac surgery patients (n = 49), stained with haematoxylin & eosin, and analysed for mean adipocyte size and non-adipocyte area. EAT thickness was measured using echocardiography. A significant positive relationship was found between EAT thickness and body mass index (BMI). When stratified into standardized BMI categories, EAT thickness was 58.7% greater (p = 0.003) in patients from the obese (7.3 ± 1.8 mm) compared to normal (4.6 ± 0.9 mm) category. BMI as a continuous variable significantly correlated with EAT thickness (r = 0.56, p < 0.0001). Conversely, no correlation was observed between adipocyte size and either BMI or EAT thickness. No difference in the non-adipocyte area was found between BMI groups. Our results suggest that the increased macroscopic EAT deposition associated with obesity is not caused by adipocyte hypertrophy. Rather, alternative remodelling via adipocyte proliferation might be responsible for the observed EAT expansion.
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Affiliation(s)
- Hamish M. Aitken-Buck
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Mohammed Moharram
- Department of Medicine, HeartOtago, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Aram A Babakr
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Robin Reijers
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Isabelle Van Hout
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Ingrid C. Fomison-Nurse
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Ramanen Sugunesegran
- Department of Cardiothoracic Surgery, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Krishna Bhagwat
- Department of Cardiothoracic Surgery, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Phillip J Davis
- Department of Cardiothoracic Surgery, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Richard W. Bunton
- Department of Cardiothoracic Surgery, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Michael J. A. Williams
- Department of Medicine, HeartOtago, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Martin K. Stiles
- Department of Cardiology, Waikato District Health Board, Hamilton, New Zealand
- Waikato Clinical School, University of Auckland, Hamilton, New Zealand
| | - Peter P. Jones
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Sean Coffey
- Department of Medicine, HeartOtago, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Regis R. Lamberts
- Department of Physiology, HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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19
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Aitken-Buck HM, Babakr AA, Coffey S, Jones PP, Tse RD, Lamberts RR. Epicardial adipocyte size does not correlate with body mass index. Cardiovasc Pathol 2019; 43:107144. [DOI: 10.1016/j.carpath.2019.07.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/18/2019] [Accepted: 07/29/2019] [Indexed: 12/31/2022] Open
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20
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Chakraborty AD, Gonano LA, Munro ML, Smith LJ, Thekkedam C, Staudacher V, Gamble AB, Macquaide N, Dulhunty AF, Jones PP. Activation of RyR2 by class I kinase inhibitors. Br J Pharmacol 2019; 176:773-786. [PMID: 30588601 DOI: 10.1111/bph.14562] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 11/26/2018] [Accepted: 12/09/2018] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Kinase inhibitors are a common treatment for cancer. Class I kinase inhibitors that target the ATP-binding pocket are particularly prevalent. Many of these compounds are cardiotoxic and can cause arrhythmias. Spontaneous release of Ca2+ via cardiac ryanodine receptors (RyR2), through a process termed store overload-induced Ca2+ release (SOICR), is a common mechanism underlying arrhythmia. We explored whether class I kinase inhibitors could modify the activity of RyR2 and trigger SOICR to determine if this contributes to the cardiotoxic nature of these compounds. EXPERIMENTAL APPROACH The impact of class I and II kinase inhibitors on SOICR was studied in HEK293 cells and ventricular myocytes using single-cell Ca2+ imaging. A specific effect on RyR2 was confirmed using single channel recordings. Ventricular myocytes were also used to determine if drug-induced changes in SOICR could be reversed using anti-SOICR agents. KEY RESULTS Class I kinase inhibitors increased the propensity of SOICR. Single channel recording showed that this was due to a specific effect on RyR2. Class II kinase inhibitors decreased the activity of RyR2 at the single channel level but had little effect on SOICR. The promotion of SOICR mediated by class I kinase inhibitors could be reversed using the anti-SOICR agent VK-II-86. CONCLUSIONS AND IMPLICATIONS Part of the cardiotoxicity of class I kinase inhibitors can be assigned to their effect on RyR2 and increase in SOICR. Compounds with anti-SOICR activity may represent an improved treatment option for patients.
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Affiliation(s)
- A D Chakraborty
- Department of Physiology, School of Biomedical Sciences, and HeartOtago, University of Otago, Dunedin, New Zealand
| | - L A Gonano
- Department of Physiology, School of Biomedical Sciences, and HeartOtago, University of Otago, Dunedin, New Zealand.,Centro de Investigaciones Cardiovasculares, CONICET La Plata, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - M L Munro
- Department of Physiology, School of Biomedical Sciences, and HeartOtago, University of Otago, Dunedin, New Zealand
| | - L J Smith
- Department of Physiology, School of Biomedical Sciences, and HeartOtago, University of Otago, Dunedin, New Zealand
| | - C Thekkedam
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - V Staudacher
- School of Pharmacy, University of Otago, Dunedin, New Zealand
| | - A B Gamble
- School of Pharmacy, University of Otago, Dunedin, New Zealand
| | - N Macquaide
- Institute of Cardiovascular and Medical Sciences and School of Life Sciences, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, UK
| | - A F Dulhunty
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - P P Jones
- Department of Physiology, School of Biomedical Sciences, and HeartOtago, University of Otago, Dunedin, New Zealand
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21
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Abstract
Contraction of cardiomyocytes is dependent on sub-cellular structures called dyads, where invaginations of the surface membrane (t-tubules) form functional junctions with the sarcoplasmic reticulum (SR). Within each dyad, Ca2+ entry through t-tubular L-type Ca2+ channels (LTCCs) elicits Ca2+ release from closely apposed Ryanodine Receptors (RyRs) in the SR membrane. The efficiency of this process is dependent on the density and macroscale arrangement of dyads, but also on the nanoscale organization of LTCCs and RyRs within them. We presently review accumulating data demonstrating the remarkable plasticity of these structures. Dyads are known to form gradually during development, with progressive assembly of both t-tubules and junctional SR terminals, and precise trafficking of LTCCs and RyRs. While dyads can exhibit compensatory remodeling when required, dyadic degradation is believed to promote impaired contractility and arrythmogenesis in cardiac disease. Recent data indicate that this plasticity of dyadic structure/function is dependent on the regulatory proteins junctophilin-2, amphiphysin-2 (BIN1), and caveolin-3, which critically arrange dyadic membranes while stabilizing the position and activity of LTCCs and RyRs. Indeed, emerging evidence indicates that clustering of both channels enables "coupled gating", implying that nanoscale localization and function are intimately linked, and may allow fine-tuning of LTCC-RyR crosstalk. We anticipate that improved understanding of dyadic plasticity will provide greater insight into the processes of cardiac compensation and decompensation, and new opportunities to target the basic mechanisms underlying heart disease.
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Affiliation(s)
- Peter P. Jones
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- HeartOtago, University of Otago, Dunedin, New Zealand
| | - Niall MacQuaide
- Institute of Cardiovascular Sciences, University of Glasgow, Glasgow, United Kingdom
- Clyde Biosciences, Glasgow, United Kingdom
| | - William E. Louch
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway
- KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
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22
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Gardner RJM, Crozier IG, Binfield AL, Love DR, Lehnert K, Gibson K, Lintott CJ, Snell RG, Jacobsen JC, Jones PP, Waddell-Smith KE, Kennedy MA, Skinner JR. Penetrance and expressivity of the R858H CACNA1C variant in a five-generation pedigree segregating an arrhythmogenic channelopathy. Mol Genet Genomic Med 2018; 7:e00476. [PMID: 30345660 PMCID: PMC6382452 DOI: 10.1002/mgg3.476] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [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: 05/21/2018] [Revised: 08/22/2018] [Accepted: 08/23/2018] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Isolated cardiac arrhythmia due to a variant in CACNA1C is of recent knowledge. Most reports have been of singleton cases or of quite small families, and estimates of penetrance and expressivity have been difficult to obtain. We here describe a large pedigree, from which such estimates have been calculated. METHODS We studied a five-generation family, in which a CACNA1C variant c.2573G>A p.Arg858His co-segregates with syncope and cardiac arrest, documenting electrocardiographic data and cardiac symptomatology. The reported patients/families from the literature with CACNA1C gene variants were reviewed, and genotype-phenotype correlations are drawn. RESULTS The range of phenotype in the studied family is wide, from no apparent effect, through an asymptomatic QT interval prolongation on electrocardiography, to episodes of presyncope and syncope, ventricular fibrillation, and sudden death. QT prolongation showed inconsistent correlation with functional cardiology. Based upon analysis of 28 heterozygous family members, estimates of penetrance and expressivity are derived. CONCLUSIONS These estimates of penetrance and expressivity, for this specific variant, may be useful in clinical practice. Review of the literature indicates that individual CACNA1C variants have their own particular genotype-phenotype correlations. We suggest that, at least in respect of the particular variant reported here, "arrhythmogenic channelopathy" may be a more fitting nomenclature than long QT syndrome.
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Affiliation(s)
- R J McKinlay Gardner
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Genetic Health Service New Zealand (South Island Hub), Christchurch Hospital, Christchurch, New Zealand.,Clinical Genetics Group, Department of Women's and Children's Health, University of Otago, Dunedin, New Zealand
| | - Ian G Crozier
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Cardiology, Christchurch Hospital, Christchurch, New Zealand
| | - Alex L Binfield
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Paediatrics, Christchurch Hospital, Christchurch, New Zealand.,Department of Paediatrics, University of Otago, Christchurch, New Zealand
| | - Donald R Love
- Cardiac Inherited Disease Group, Auckland, New Zealand.,LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Klaus Lehnert
- Cardiac Inherited Disease Group, Auckland, New Zealand.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Kate Gibson
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Genetic Health Service New Zealand (South Island Hub), Christchurch Hospital, Christchurch, New Zealand
| | - Caroline J Lintott
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Genetic Health Service New Zealand (South Island Hub), Christchurch Hospital, Christchurch, New Zealand
| | - Russell G Snell
- Cardiac Inherited Disease Group, Auckland, New Zealand.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Jessie C Jacobsen
- Cardiac Inherited Disease Group, Auckland, New Zealand.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Peter P Jones
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Physiology and HeartOtago, University of Otago, Dunedin, New Zealand
| | - Kathryn E Waddell-Smith
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Cardiology, Auckland City Hospital, Auckland, New Zealand
| | - Martin A Kennedy
- Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - Jonathan R Skinner
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Cardiology, Auckland City Hospital, Auckland, New Zealand
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23
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Daniels LJ, Wallace RS, Nicholson OM, Wilson GA, McDonald FJ, Jones PP, Baldi JC, Lamberts RR, Erickson JR. Inhibition of calcium/calmodulin-dependent kinase II restores contraction and relaxation in isolated cardiac muscle from type 2 diabetic rats. Cardiovasc Diabetol 2018; 17:89. [PMID: 29903013 PMCID: PMC6001139 DOI: 10.1186/s12933-018-0732-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [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: 03/14/2018] [Accepted: 06/06/2018] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Calcium/calmodulin-dependent kinase II-delta (CaMKIIδ) activity is enhanced during hyperglycemia and has been shown to alter intracellular calcium handling in cardiomyocytes, ultimately leading to reduced cardiac performance. However, the effects of CaMKIIδ on cardiac contractility during type 2 diabetes are undefined. METHODS We examined the expression and activation of CaMKIIδ in right atrial appendages from non-diabetic and type 2 diabetic patients (n = 7 patients per group) with preserved ejection fraction, and also in right ventricular tissue from Zucker Diabetic Fatty rats (ZDF) (n = 5-10 animals per group) during early diabetic cardiac dysfunction, using immunoblot. We also measured whole heart function of ZDF and control rats using echocardiography. Then we measured contraction and relaxation parameters of isolated trabeculae from ZDF to control rats in the presence and absence of CaMKII inhibitors. RESULTS CaMKIIδ phosphorylation (at Thr287) was increased in both the diabetic human and animal tissue, indicating increased CaMKIIδ activation in the type 2 diabetic heart. Basal cardiac contractility and relaxation were impaired in the cardiac muscles from the diabetic rats, and CaMKII inhibition with KN93 partially restored contractility and relaxation. Autocamtide-2-related-inhibitor peptide (AIP), another CaMKII inhibitor that acts via a different mechanism than KN93, fully restored cardiac contractility and relaxation. CONCLUSIONS Our results indicate that CaMKIIδ plays a key role in modulating performance of the diabetic heart, and moreover, suggest a potential therapeutic role for CaMKII inhibitors in improving myocardial function during type 2 diabetes.
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Affiliation(s)
- Lorna J Daniels
- Otago School of Medical Sciences, Department of Physiology and HeartOtago, University of Otago, 270 Great King Street, Dunedin, 9016, New Zealand
| | - Rachel S Wallace
- Otago School of Medical Sciences, Department of Physiology and HeartOtago, University of Otago, 270 Great King Street, Dunedin, 9016, New Zealand
| | - Olivia M Nicholson
- Otago School of Medical Sciences, Department of Physiology and HeartOtago, University of Otago, 270 Great King Street, Dunedin, 9016, New Zealand
| | - Genevieve A Wilson
- Otago School of Medical Sciences, Department of Medicine and HeartOtago, University of Otago, Dunedin, New Zealand
| | - Fiona J McDonald
- Otago School of Medical Sciences, Department of Physiology and HeartOtago, University of Otago, 270 Great King Street, Dunedin, 9016, New Zealand
| | - Peter P Jones
- Otago School of Medical Sciences, Department of Physiology and HeartOtago, University of Otago, 270 Great King Street, Dunedin, 9016, New Zealand
| | - J Chris Baldi
- Otago School of Medical Sciences, Department of Medicine and HeartOtago, University of Otago, Dunedin, New Zealand
| | - Regis R Lamberts
- Otago School of Medical Sciences, Department of Physiology and HeartOtago, University of Otago, 270 Great King Street, Dunedin, 9016, New Zealand
| | - Jeffrey R Erickson
- Otago School of Medical Sciences, Department of Physiology and HeartOtago, University of Otago, 270 Great King Street, Dunedin, 9016, New Zealand.
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24
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Babakr AA, Fomison-Nurse IC, Jones PP, Lamberts RR. 41Does human epicardial adipose tissue enhance atrial fibrillation induced by beta adrenergic stimulation in human cardiac muscles? Cardiovasc Res 2018. [DOI: 10.1093/cvr/cvy060.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- A A Babakr
- University of Otago, Department of Physiology, Dunedin, New Zealand
| | | | - P P Jones
- University of Otago, Department of Physiology, Dunedin, New Zealand
| | - R R Lamberts
- University of Otago, Department of Physiology, Dunedin, New Zealand
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25
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Lamberts RR, Babakr AA, Fomison-Nurse IC, Jones PP. P131Effect of human epicardial adipose tissue on calcium-overload-induced atrial fibrillation in human cardiac muscles. Cardiovasc Res 2018. [DOI: 10.1093/cvr/cvy060.093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- R R Lamberts
- Department of Physiology, School of Biomedical Sciences, HeartOtago, University of Otago, Dunedin, New Zealand
| | - A A Babakr
- Department of Physiology, School of Biomedical Sciences, HeartOtago, University of Otago, Dunedin, New Zealand
| | - I C Fomison-Nurse
- Department of Physiology, School of Biomedical Sciences, HeartOtago, University of Otago, Dunedin, New Zealand
| | - P P Jones
- Department of Physiology, School of Biomedical Sciences, HeartOtago, University of Otago, Dunedin, New Zealand
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26
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Jones PP, Guo W, Chen SRW. Control of cardiac ryanodine receptor by sarcoplasmic reticulum luminal Ca 2. J Gen Physiol 2017; 149:867-875. [PMID: 28798281 PMCID: PMC5583710 DOI: 10.1085/jgp.201711805] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 06/25/2017] [Accepted: 07/18/2017] [Indexed: 12/22/2022] Open
Abstract
Jones et al. propose that SR luminal Ca2+ regulates RyR2 activity via a luminal Ca2+ sensor distinct from the cytosolic Ca2+ sensor.
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Affiliation(s)
- Peter P Jones
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, Otago, New Zealand .,HeartOtago, University of Otago, Dunedin, Otago, New Zealand
| | - Wenting Guo
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - S R Wayne Chen
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
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27
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Gonano LA, Jones PP. FK506-binding proteins 12 and 12.6 (FKBPs) as regulators of cardiac Ryanodine Receptors: Insights from new functional and structural knowledge. Channels (Austin) 2017. [PMID: 28636428 DOI: 10.1080/19336950.2017.1344799] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Ryanodine Receptors (RyRs) are intracellular Ca2+ channels that mediate Ca2+ flux from the sarco(endo)plasmic reticulum in many cell types. The interaction of RyRs with FK506-binding proteins (FKBPs) has been proposed as an important regulatory mechanism, where the loss of this interaction leads to channel dysfunction. In the heart, phosphorylation of RyR has been suggested to disrupt the RyR-FKBP interaction promoting altered Ca2+ signaling, heart failure and arrhythmias. However, the functional result of FKBP interaction with RyR and how this interaction is regulated remains highly controversial. Recently, high resolution structures of RyR have provided novel aspects to the ongoing debate. This review will discuss the most recent functional data in light of these new structures.
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Affiliation(s)
- Luis A Gonano
- a Department of Physiology , School of Biomedical Sciences and HeartOtago, University of Otago , Dunedin, Otago , New Zealand
| | - Peter P Jones
- a Department of Physiology , School of Biomedical Sciences and HeartOtago, University of Otago , Dunedin, Otago , New Zealand
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28
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Xiao Z, Guo W, Sun B, Hunt DJ, Wei J, Liu Y, Wang Y, Wang R, Jones PP, Back TG, Chen SRW. Enhanced Cytosolic Ca2+ Activation Underlies a Common Defect of Central Domain Cardiac Ryanodine Receptor Mutations Linked to Arrhythmias. J Biol Chem 2016; 291:24528-24537. [PMID: 27733687 DOI: 10.1074/jbc.m116.756528] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [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: 08/31/2016] [Revised: 10/02/2016] [Indexed: 01/21/2023] Open
Abstract
Recent three-dimensional structural studies reveal that the central domain of ryanodine receptor (RyR) serves as a transducer that converts long-range conformational changes into the gating of the channel pore. Interestingly, the central domain encompasses one of the mutation hotspots (corresponding to amino acid residues 3778-4201) that contains a number of cardiac RyR (RyR2) mutations associated with catecholaminergic polymorphic ventricular tachycardia (CPVT) and atrial fibrillation (AF). However, the functional consequences of these central domain RyR2 mutations are not well understood. To gain insights into the impact of the mutation and the role of the central domain in channel function, we generated and characterized eight disease-associated RyR2 mutations in the central domain. We found that all eight central domain RyR2 mutations enhanced the Ca2+-dependent activation of [3H]ryanodine binding, increased cytosolic Ca2+-induced fractional Ca2+ release, and reduced the activation and termination thresholds for spontaneous Ca2+ release in HEK293 cells. We also showed that racemic carvedilol and the non-beta-blocking carvedilol enantiomer, (R)-carvedilol, suppressed spontaneous Ca2+ oscillations in HEK293 cells expressing the central domain RyR2 mutations associated with CPVT and AF. These data indicate that the central domain is an important determinant of cytosolic Ca2+ activation of RyR2. These results also suggest that altered cytosolic Ca2+ activation of RyR2 represents a common defect of RyR2 mutations associated with CPVT and AF, which could potentially be suppressed by carvedilol or (R)-carvedilol.
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Affiliation(s)
- Zhichao Xiao
- From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Wenting Guo
- From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Bo Sun
- From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Donald J Hunt
- From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Jinhong Wei
- From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Yingjie Liu
- From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Yundi Wang
- From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Ruiwu Wang
- From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Peter P Jones
- the Department of Physiology, Otago School of Medical Sciences and HeartOtago, University of Otago, Dunedin 9054, New Zealand, and
| | - Thomas G Back
- the Department of Chemistry, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - S R Wayne Chen
- From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada,.
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29
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Diong C, Jones PP, Tsuchimochi H, Gray EA, Hughes G, Inagaki T, Bussey CT, Fujii Y, Umetani K, Shirai M, Schwenke DO. Sympathetic hyper-excitation in obesity and pulmonary hypertension: physiological relevance to the 'obesity paradox'. Int J Obes (Lond) 2016; 40:938-46. [PMID: 27001546 DOI: 10.1038/ijo.2016.33] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 01/10/2016] [Accepted: 01/28/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND Within the lung, sympathetic nerve activity (SNA) has an important role in facilitating pulmonary vasodilation. As SNA is elevated in obesity, we aimed to assess the impact of sympathetic hyper-excitation on pulmonary vascular homeostasis in obesity, and its potential role in ameliorating the severity of pulmonary hypertension (PH); the well-documented 'obesity paradox' phenomenon. METHODS Zucker obese and lean rats were exposed to normoxia or chronic hypoxia (CH-10% O2) for 2 weeks. Subsequently, pulmonary SNA (pSNA) was recorded (electrophysiology), or the pulmonary microcirculation was visualized using Synchrotron microangiography. Acute hypoxic pulmonary vasoconstriction (HPV) was assessed before and after blockade of β1-adrenergic receptors (ARs) (atenolol, 3 mg kg(-1)) and β1+β2-adrenergic (propranolol, 2 mg kg(-1)). RESULTS pSNA of normoxic obese rats was higher than lean counterparts (2.4 and 0.5 μV s, respectively). SNA was enhanced following the development of PH in lean rats, but more so in obese rats (1.7 and 6.8 μV s, respectively). The magnitude of HPV was similar for all groups (for example, ~20% constriction of the 200-300 μm vessels). Although β-blockade did not modify HPV in lean rats, it significantly augmented the HPV in normoxic obese rats (β1 and β2 blockade), and more so in obese rats with PH (β2-blockade alone). Western blots showed, while the expression of pulmonary β1-ARs was similar for all rats, the expression of β2-ARs was downregulated in obesity and PH. CONCLUSIONS This study suggests that sympathetic hyper-excitation in obesity may have an important role in constraining the severity of PH and, thus, contribute in part to the 'obesity paradox' in PH.
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Affiliation(s)
- C Diong
- Department of Physiology-HeartOtago, University of Otago, Dunedin, New Zealand
| | - P P Jones
- Department of Physiology-HeartOtago, University of Otago, Dunedin, New Zealand
| | - H Tsuchimochi
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan
| | - E A Gray
- Department of Physiology-HeartOtago, University of Otago, Dunedin, New Zealand
| | - G Hughes
- Department of Physiology-HeartOtago, University of Otago, Dunedin, New Zealand
| | - T Inagaki
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan
| | - C T Bussey
- Department of Physiology-HeartOtago, University of Otago, Dunedin, New Zealand
| | - Y Fujii
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan
| | - K Umetani
- Japan Synchrotron Radiation Research Institute, Hyogo, Japan
| | - M Shirai
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan
| | - D O Schwenke
- Department of Physiology-HeartOtago, University of Otago, Dunedin, New Zealand
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Thaung HPA, Baldi JC, Wang HY, Hughes G, Cook RF, Bussey CT, Sheard PW, Bahn A, Jones PP, Schwenke DO, Lamberts RR. Increased Efferent Cardiac Sympathetic Nerve Activity and Defective Intrinsic Heart Rate Regulation in Type 2 Diabetes. Diabetes 2015; 64:2944-56. [PMID: 25784543 DOI: 10.2337/db14-0955] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 03/09/2015] [Indexed: 11/13/2022]
Abstract
Elevated sympathetic nerve activity (SNA) coupled with dysregulated β-adrenoceptor (β-AR) signaling is postulated as a major driving force for cardiac dysfunction in patients with type 2 diabetes; however, cardiac SNA has never been assessed directly in diabetes. Our aim was to measure the sympathetic input to and the β-AR responsiveness of the heart in the type 2 diabetic heart. In vivo recording of SNA of the left efferent cardiac sympathetic branch of the stellate ganglion in Zucker diabetic fatty rats revealed an elevated resting cardiac SNA and doubled firing rate compared with nondiabetic rats. Ex vivo, in isolated denervated hearts, the intrinsic heart rate was markedly reduced. Contractile and relaxation responses to β-AR stimulation with dobutamine were compromised in externally paced diabetic hearts, but not in diabetic hearts allowed to regulate their own heart rate. Protein levels of left ventricular β1-AR and Gs (guanine nucleotide binding protein stimulatory) were reduced, whereas left ventricular and right atrial β2-AR and Gi (guanine nucleotide binding protein inhibitory regulatory) levels were increased. The elevated resting cardiac SNA in type 2 diabetes, combined with the reduced cardiac β-AR responsiveness, suggests that the maintenance of normal cardiovascular function requires elevated cardiac sympathetic input to compensate for changes in the intrinsic properties of the diabetic heart.
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Affiliation(s)
- H P Aye Thaung
- HeartOtago, Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - J Chris Baldi
- Department of Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Heng-Yu Wang
- HeartOtago, Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Gillian Hughes
- HeartOtago, Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Rosalind F Cook
- HeartOtago, Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Carol T Bussey
- HeartOtago, Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Phil W Sheard
- HeartOtago, Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Andrew Bahn
- HeartOtago, Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Peter P Jones
- HeartOtago, Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Daryl O Schwenke
- HeartOtago, Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Regis R Lamberts
- HeartOtago, Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
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Thaung HPA, Yao Y, Bussey CT, Hughes G, Jones PP, Bahn A, Sammut IA, Lamberts RR. Chronic bilateral renal denervation reduces cardiac hypertrophic remodelling but not β-adrenergic responsiveness in hypertensive type 1 diabetic rats. Exp Physiol 2015; 100:628-39. [DOI: 10.1113/ep085021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 04/13/2015] [Indexed: 11/08/2022]
Affiliation(s)
- H. P. Aye Thaung
- Department of Physiology - HeartOtago, Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
| | - Yimin Yao
- Department of Pharmacology and Toxicology, Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
| | - Carol T. Bussey
- Department of Physiology - HeartOtago, Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
| | - Gillian Hughes
- Department of Physiology - HeartOtago, Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
| | - Peter P. Jones
- Department of Physiology - HeartOtago, Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
| | - Andrew Bahn
- Department of Physiology - HeartOtago, Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
| | - Ivan A. Sammut
- Department of Pharmacology and Toxicology, Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
| | - Regis R. Lamberts
- Department of Physiology - HeartOtago, Otago School of Medical Sciences; University of Otago; Dunedin New Zealand
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Bussey CT, Hughes G, Saxena P, Galvin IF, Bunton RW, Noye MK, Coffey S, Williams MJA, Baldi JC, Jones PP, Lamberts RR. Chamber-specific changes in calcium-handling proteins in the type 2 diabetic human heart with preserved ejection fraction. Int J Cardiol 2015; 193:53-5. [PMID: 26005176 DOI: 10.1016/j.ijcard.2015.05.053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 05/09/2015] [Indexed: 10/23/2022]
Affiliation(s)
- Carol T Bussey
- Department of Physiology - HeartOtago, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Gillian Hughes
- Department of Physiology - HeartOtago, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Pankaj Saxena
- Department of Cardiothoracic Surgery, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Ivor F Galvin
- Department of Cardiothoracic Surgery, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Richard W Bunton
- Department of Cardiothoracic Surgery, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Marilyn K Noye
- Department of Medicine - HeartOtago, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Sean Coffey
- Department of Medicine - HeartOtago, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand; NIHR Oxford Biomedical Research Centre, John Radcliffe Hospital, Oxford, United Kingdom
| | - Michael J A Williams
- Department of Medicine - HeartOtago, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - J Chris Baldi
- Department of Medicine - HeartOtago, Dunedin School of Medicine, Dunedin Hospital, Dunedin, New Zealand
| | - Peter P Jones
- Department of Physiology - HeartOtago, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.
| | - Regis R Lamberts
- Department of Physiology - HeartOtago, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.
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Liu Y, Sun B, Xiao Z, Wang R, Guo W, Zhang JZ, Mi T, Wang Y, Jones PP, Van Petegem F, Chen SRW. Roles of the NH2-terminal domains of cardiac ryanodine receptor in Ca2+ release activation and termination. J Biol Chem 2015; 290:7736-46. [PMID: 25627681 DOI: 10.1074/jbc.m114.618827] [Citation(s) in RCA: 16] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The NH2-terminal region (residues 1-543) of the cardiac ryanodine receptor (RyR2) harbors a large number of mutations associated with cardiac arrhythmias and cardiomyopathies. Functional studies have revealed that the NH2-terminal region is involved in the activation and termination of Ca(2+) release. The three-dimensional structure of the NH2-terminal region has recently been solved. It is composed of three domains (A, B, and C). However, the roles of these individual domains in Ca(2+) release activation and termination are largely unknown. To understand the functional significance of each of these NH2-terminal domains, we systematically deleted these domains and assessed their impact on caffeine- or Ca(2+)-induced Ca(2+) release and store overload-induced Ca(2+) release (SOICR) in HEK293 cells. We found that all deletion mutants were capable of forming caffeine- and ryanodine-sensitive functional channels, indicating that the NH2-terminal region is not essential for channel gating. Ca(2+) release measurements revealed that deleting domain A markedly reduced the threshold for SOICR termination but had no effect on caffeine or Ca(2+) activation or the threshold for SOICR activation, whereas deleting domain B substantially enhanced caffeine and Ca(2+) activation and lowered the threshold for SOICR activation and termination. Conversely, deleting domain C suppressed caffeine activation, abolished Ca(2+) activation and SOICR, and diminished protein expression. These results suggest that domain A is involved in channel termination, domain B is involved in channel suppression, and domain C is critical for channel activation and expression. Our data shed new insights into the structure-function relationship of the NH2-terminal domains of RyR2 and the action of NH2-terminal disease mutations.
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Affiliation(s)
- Yingjie Liu
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Bo Sun
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Zhichao Xiao
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Ruiwu Wang
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Wenting Guo
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Joe Z Zhang
- Department of Physiology and HeartOtago, University of Otago, Dunedin 9054, New Zealand, and
| | - Tao Mi
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Yundi Wang
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Peter P Jones
- Department of Physiology and HeartOtago, University of Otago, Dunedin 9054, New Zealand, and
| | - Filip Van Petegem
- Cardiovascular Research Group, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - S R Wayne Chen
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada,
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Zhang JZ, Waddell HMM, Jones PP. Regulation of RYR2 by sarcoplasmic reticulum Ca(2+). Clin Exp Pharmacol Physiol 2015; 42:720-6. [PMID: 25603835 DOI: 10.1111/1440-1681.12364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [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: 07/06/2014] [Revised: 09/17/2014] [Accepted: 10/09/2014] [Indexed: 11/28/2022]
Abstract
Ca(2+) is arguably the most important ion involved in the contraction of the heart. The cardiac ryanodine receptor (RyR2), the major Ca(2+) release channel located in the sarcoplasmic reticulum (SR) membrane, is responsible for releasing the bulk of Ca(2+) required for contraction. Moreover, RyR2 is also crucial for maintaining SR Ca(2+) homeostasis by releasing Ca(2+) from the SR when it becomes overloaded with Ca(2+) . During normal contraction, RyR2 is activated by cytosolic Ca(2+) , whereas during store overload conditions, the opening of RyR2 is governed by SR Ca(2+) . Although the process of the cytosolic control of RyR2 is well established, the molecular mechanism by which SR luminal Ca(2+) regulates RyR2 has only recently been elucidated and remains controversial. In addition to the activation of RyR2, SR luminal Ca(2+) also determines when the RyR2 channel closes. RyR2-mediated Ca(2+) release from the SR does not continue until the SR is completely depleted. Rather, it ceases when SR luminal Ca(2+) falls below a certain level. Given the importance of SR Ca(2+) , it is not surprising that the SR luminal Ca(2+) level is tightly controlled by SR Ca(2+) -buffering proteins. Consequently, the opening and closing of RyR2 is heavily influenced by the presence of such proteins, particularly those associated with RyR2, such as calsequestrin and the histidine-rich Ca(2+) -binding protein. These proteins appear to indirectly alter RyR2 activity by modifying the microdomain SR Ca(2+) level surrounding RyR2.
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Affiliation(s)
- Joe Z Zhang
- Department of Physiology and HeartOtago, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Helen M M Waddell
- Department of Physiology and HeartOtago, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Peter P Jones
- Department of Physiology and HeartOtago, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
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Zhang JZ, McLay JC, Jones PP. The arrhythmogenic human HRC point mutation S96A leads to spontaneous Ca2+ release due to an impaired ability to buffer store Ca2+. J Mol Cell Cardiol 2014; 74:22-31. [DOI: 10.1016/j.yjmcc.2014.04.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 04/14/2014] [Accepted: 04/28/2014] [Indexed: 11/26/2022]
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Lamberts RR, Lingam SJ, Wang HY, Bollen IAE, Hughes G, Galvin IF, Bunton RW, Bahn A, Katare R, Baldi JC, Williams MJA, Saxena P, Coffey S, Jones PP. Impaired relaxation despite upregulated calcium-handling protein atrial myocardium from type 2 diabetic patients with preserved ejection fraction. Cardiovasc Diabetol 2014; 13:72. [PMID: 24708792 PMCID: PMC3997226 DOI: 10.1186/1475-2840-13-72] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 03/26/2014] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Diastolic dysfunction is a key factor in the development and pathology of cardiac dysfunction in diabetes, however the exact underlying mechanism remains unknown, especially in humans. We aimed to measure contraction, relaxation, expression of calcium-handling proteins and fibrosis in myocardium of diabetic patients with preserved systolic function. METHODS Right atrial appendages from patients with type 2 diabetes mellitus (DM, n = 20) and non-diabetic patients (non-DM, n = 36), all with preserved ejection fraction and undergoing coronary artery bypass grafting (CABG), were collected. From appendages, small cardiac muscles, trabeculae, were isolated to measure basal and β-adrenergic stimulated myocardial function. Expression levels of calcium-handling proteins, sarcoplasmic reticulum Ca2+ ATPase (SERCA2a) and phospholamban (PLB), and of β1-adrenoreceptors were determined in tissue samples by Western blot. Collagen deposition was determined by picro-sirius red staining. RESULTS In trabeculae from diabetic samples, contractile function was preserved, but relaxation was prolonged (Tau: 74 ± 13 ms vs. 93 ± 16 ms, non-DM vs. DM, p = 0.03). The expression of SERCA2a was increased in diabetic myocardial tissue (0.75 ± 0.09 vs. 1.23 ± 0.15, non-DM vs. DM, p = 0.007), whereas its endogenous inhibitor PLB was reduced (2.21 ± 0.45 vs. 0.42 ± 0.11, non-DM vs. DM, p = 0.01). Collagen deposition was increased in diabetic samples. Moreover, trabeculae from diabetic patients were unresponsive to β-adrenergic stimulation, despite no change in β1-adrenoreceptor expression levels. CONCLUSIONS Human type 2 diabetic atrial myocardium showed increased fibrosis without systolic dysfunction but with impaired relaxation, especially during β-adrenergic challenge. Interestingly, changes in calcium-handling protein expression suggests accelerated active calcium re-uptake, thus improved relaxation, indicating a compensatory calcium-handling mechanism in diabetes in an attempt to maintain diastolic function at rest despite impaired relaxation in the diabetic fibrotic atrial myocardium. Our study addresses important aspects of the underlying mechanisms of diabetes-associated diastolic dysfunction, which is crucial to developing new therapeutic treatments.
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Affiliation(s)
- Regis R Lamberts
- Department of Physiology - HeartOtago, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.
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Bai Y, Jones PP, Guo J, Zhong X, Clark RB, Zhou Q, Wang R, Vallmitjana A, Benitez R, Hove-Madsen L, Semeniuk L, Guo A, Song LS, Duff HJ, Chen SRW. Phospholamban knockout breaks arrhythmogenic Ca²⁺ waves and suppresses catecholaminergic polymorphic ventricular tachycardia in mice. Circ Res 2013; 113:517-26. [PMID: 23856523 DOI: 10.1161/circresaha.113.301678] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
RATIONALE Phospholamban (PLN) is an inhibitor of cardiac sarco(endo)plasmic reticulum Ca²⁺ ATPase. PLN knockout (PLN-KO) enhances sarcoplasmic reticulum Ca²⁺ load and Ca²⁺ leak. Conversely, PLN-KO accelerates Ca²⁺ sequestration and aborts arrhythmogenic spontaneous Ca²⁺ waves (SCWs). An important question is whether these seemingly paradoxical effects of PLN-KO exacerbate or protect against Ca²⁺-triggered arrhythmias. OBJECTIVE We investigate the impact of PLN-KO on SCWs, triggered activities, and stress-induced ventricular tachyarrhythmias (VTs) in a mouse model of cardiac ryanodine-receptor (RyR2)-linked catecholaminergic polymorphic VT. METHODS AND RESULTS We generated a PLN-deficient, RyR2-mutant mouse model (PLN-/-/RyR2-R4496C+/-) by crossbreeding PLN-KO mice with catecholaminergic polymorphic VT-associated RyR2-R4496C mutant mice. Ca²⁺ imaging and patch-clamp recording revealed cell-wide propagating SCWs and triggered activities in RyR2-R4496C+/- ventricular myocytes during sarcoplasmic reticulum Ca²⁺ overload. PLN-KO fragmented these cell-wide SCWs into mini-waves and Ca²⁺ sparks and suppressed the triggered activities evoked by sarcoplasmic reticulum Ca²⁺ overload. Importantly, these effects of PLN-KO were reverted by partially inhibiting sarco(endo)plasmic reticulum Ca²⁺ ATPase with 2,5-di-tert-butylhydroquinone. However, Bay K, caffeine, or Li⁺ failed to convert mini-waves to cell-wide SCWs in PLN-/-/RyR2-R4496C+/- ventricular myocytes. Furthermore, ECG analysis showed that PLN-KO mice are not susceptible to stress-induced VTs. On the contrary, PLN-KO protected RyR2-R4496C mutant mice from stress-induced VTs. CONCLUSIONS Our results demonstrate that despite severe sarcoplasmic reticulum Ca²⁺ leak, PLN-KO suppresses triggered activities and stress-induced VTs in a mouse model of catecholaminergic polymorphic VT. These data suggest that breaking up cell-wide propagating SCWs by enhancing Ca²⁺ sequestration represents an effective approach for suppressing Ca²⁺-triggered arrhythmias.
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Affiliation(s)
- Yunlong Bai
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
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Jones PP, Ball RC, Connaughton C. Nonlinear least-squares method for the inverse droplet coagulation problem. Phys Rev E Stat Nonlin Soft Matter Phys 2013; 88:012138. [PMID: 23944445 DOI: 10.1103/physreve.88.012138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Indexed: 06/02/2023]
Abstract
If the rates, K(x,y), at which particles of size x coalesce with particles of size y is known, then the mean-field evolution of the particle size distribution of an ensemble of irreversibly coalescing particles is described by the Smoluchowski equation. We study the corresponding inverse problem which aims to determine the coalescence rates K(x,y) from measurements of the particle size distribution. We assume that K(x,y) is a homogeneous function of its arguments, a case which occurs commonly in practice. The problem of determining K(x,y), a function to two variables, then reduces to the simpler problem of determining a function of a single variable plus two exponents, μ and ν, which characterize the scaling properties of K(x,y). The price of this simplification is that the resulting least-squares problem is nonlinear in the exponents μ and ν. We demonstrate the effectiveness of the method on a selection of coalescence problems arising in polymer physics, cloud science, and astrophysics. The applications include examples in which the particle size distribution is stationary owing to the presence of sources and sinks of particles and examples in which the particle size distribution is undergoing self-similar relaxation in time.
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Affiliation(s)
- Peter P Jones
- Centre for Complexity Science, University of Warwick, Coventry CV4 7AL, United Kindgom
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Ball RC, Connaughton C, Jones PP, Rajesh R, Zaboronski O. Collective oscillations in irreversible coagulation driven by monomer inputs and large-cluster outputs. Phys Rev Lett 2012; 109:168304. [PMID: 23215141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Received: 05/20/2012] [Indexed: 06/01/2023]
Abstract
We describe collective oscillatory behavior in the kinetics of irreversible coagulation with a constant input of monomers and removal of large clusters. For a broad class of collision rates, this system reaches a nonequilibrium stationary state at large times and the cluster size distribution tends to a universal form characterized by a constant flux of mass through the space of cluster sizes. Universality, in this context, means that the stationary state becomes independent of the cutoff as the cutoff grows. This universality is lost, however, if the aggregation rate between large and small clusters increases sufficiently steeply as a function of cluster sizes. We identify a transition to a regime in which the stationary state vanishes as the cutoff grows. This nonuniversal stationary state becomes unstable as the cutoff is increased. It undergoes a Hopf bifurcation after which the stationary state is replaced by persistent and periodic collective oscillations. These oscillations, which bear some similarities to relaxation oscillations in excitable media, carry pulses of mass through the space of cluster sizes such that the average mass flux through any cluster size remains constant. Universality is partially restored in the sense that the scaling of the period and amplitude of oscillation is inherited from the dynamical scaling exponents of the universal regime.
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Affiliation(s)
- Robin C Ball
- Centre for Complexity Science, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
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Benitez R, Vallmitjana A, Hove-Madsen L, Jones PP. Detection and Classification of Spontaneous Calcium Release Events in Cardiac Myocytes. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.1702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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Zhou Q, Xiao J, Jiang D, Wang R, Vembaiyan K, Wang A, Smith CD, Xie C, Chen W, Zhang J, Tian X, Jones PP, Zhong X, Guo A, Chen H, Zhang L, Zhu W, Yang D, Li X, Chen J, Gillis AM, Duff HJ, Cheng H, Feldman AM, Song LS, Fill M, Back TG, Chen SRW. Carvedilol and its new analogs suppress arrhythmogenic store overload-induced Ca2+ release. Nat Med 2011; 17:1003-9. [PMID: 21743453 DOI: 10.1038/nm.2406] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 05/23/2011] [Indexed: 12/31/2022]
Abstract
Carvedilol is one of the most effective beta blockers for preventing ventricular tachyarrhythmias in heart failure, but the mechanisms underlying its favorable antiarrhythmic benefits remain unclear. Spontaneous Ca(2+) waves, also called store overload-induced Ca(2+) release (SOICR), evoke ventricular tachyarrhythmias in individuals with heart failure. Here we show that carvedilol is the only beta blocker tested that effectively suppresses SOICR by directly reducing the open duration of the cardiac ryanodine receptor (RyR2). This unique anti-SOICR activity of carvedilol, combined with its beta-blocking activity, probably contributes to its favorable antiarrhythmic effect. To enable optimal titration of carvedilol's actions as a beta blocker and as a suppressor of SOICR separately, we developed a new SOICR-inhibiting, minimally beta-blocking carvedilol analog, VK-II-86. VK-II-86 prevented stress-induced ventricular tachyarrhythmias in RyR2-mutant mice and did so more effectively when combined with either of the selective beta blockers metoprolol or bisoprolol. Combining SOICR inhibition with optimal beta blockade has the potential to provide antiarrhythmic therapy that can be tailored to individual patients.
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Affiliation(s)
- Qiang Zhou
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
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Mufti RE, Brett SE, Tran CH, El‐Rahman RA, Anfinogenova Y, El‐Yazbi A, Cole WC, Jones PP, Chen WSW, Welsh DG. Intravascular Pressure Augments Cerebral Arterial Constriction by Inducing Voltage‐Insensitive Ca2+ Waves. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.1024.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Rania E. Mufti
- Physiology and PharmacologyUniversity of CalgaryCalgaryABCanada
| | | | - Cam Ha Tran
- Physiology and PharmacologyUniversity of CalgaryCalgaryABCanada
| | | | | | - Ahmed El‐Yazbi
- Physiology and PharmacologyUniversity of CalgaryCalgaryABCanada
| | - William C. Cole
- Physiology and PharmacologyUniversity of CalgaryCalgaryABCanada
| | - Peter P. Jones
- Physiology and PharmacologyUniversity of CalgaryCalgaryABCanada
| | - Wayne SW Chen
- Physiology and PharmacologyUniversity of CalgaryCalgaryABCanada
| | - Donald G. Welsh
- Physiology and PharmacologyUniversity of CalgaryCalgaryABCanada
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Wang R, Zhong X, Meng X, Koop A, Tian X, Jones PP, Fruen BR, Wagenknecht T, Liu Z, Chen SRW. Localization of the dantrolene-binding sequence near the FK506-binding protein-binding site in the three-dimensional structure of the ryanodine receptor. J Biol Chem 2011; 286:12202-12. [PMID: 21262961 DOI: 10.1074/jbc.m110.194316] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dantrolene is believed to stabilize interdomain interactions between the NH2-terminal and central regions of ryanodine receptors by binding to the NH2-terminal residues 590-609 in skeletal ryanodine receptor (RyR1) and residues 601-620 in cardiac ryanodine receptor (RyR2). To gain further insight into the structural basis of dantrolene action, we have attempted to localize the dantrolene-binding sequence in RyR1/RyR2 by using GFP as a structural marker and three-dimensional cryo-EM. We inserted GFP into RyR2 after residues Arg-626 and Tyr-846 to generate GFP-RyR2 fusion proteins, RyR2Arg-626-GFP and RyR2Tyr-846-GFP. Insertion of GFP after residue Arg-626 abolished the binding of a bulky GST- or cyan fluorescent protein-tagged FKBP12.6 but not the binding of a smaller, nontagged FKBP12.6, suggesting that residue Arg-626 and the dantrolene-binding sequence are located near the FKBP12.6-binding site. Using cryo-EM, we have mapped the three-dimensional location of Tyr-846-GFP to domain 9, which is also adjacent to the FKBP12.6-binding site. To further map the three-dimensional location of the dantrolene-binding sequence, we generated 10 FRET pairs based on four known three-dimensional locations (FKBP12.6, Ser-437-GFP, Tyr-846-GFP, and Ser-2367-GFP). Based on the FRET efficiencies of these FRET pairs and the corresponding distance relationships, we mapped the three-dimensional location of Arg-626-GFP or -cyan fluorescent protein, hence the dantrolene-binding sequence, to domain 9 near the FKBP12.6-binding site but distant to the central region around residue Ser-2367. An allosteric mechanism by which dantrolene stabilizes interdomain interactions between the NH2-terminal and central regions is proposed.
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Affiliation(s)
- Ruiwu Wang
- Libin Cardiovascular Institute of Alberta, Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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Mufti RE, Brett SE, Tran CHT, Abd El-Rahman R, Anfinogenova Y, El-Yazbi A, Cole WC, Jones PP, Chen SRW, Welsh DG. Intravascular pressure augments cerebral arterial constriction by inducing voltage-insensitive Ca2+ waves. J Physiol 2010; 588:3983-4005. [PMID: 20736418 DOI: 10.1113/jphysiol.2010.193300] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
This study examined whether elevated intravascular pressure stimulates asynchronous Ca(2+) waves in cerebral arterial smooth muscle cells and if their generation contributes to myogenic tone development. The endothelium was removed from rat cerebral arteries, which were then mounted in an arteriograph, pressurized (20-100 mmHg) and examined under a variety of experimental conditions. Diameter and membrane potential (V(M)) were monitored using conventional techniques; Ca(2+) wave generation and myosin light chain (MLC(20))/MYPT1 (myosin phosphatase targeting subunit) phosphorylation were assessed by confocal microscopy and Western blot analysis, respectively. Elevating intravascular pressure increased the proportion of smooth muscle cells firing asynchronous Ca(2+) waves as well as event frequency. Ca(2+) wave augmentation occurred primarily at lower intravascular pressures (<60 mmHg) and ryanodine, a plant alkaloid that depletes the sarcoplasmic reticulum (SR) of Ca(2+), eliminated these events. Ca(2+) wave generation was voltage insensitive as Ca(2+) channel blockade and perturbations in extracellular [K(+)] had little effect on measured parameters. Ryanodine-induced inhibition of Ca(2+) waves attenuated myogenic tone and MLC(20) phosphorylation without altering arterial V(M). Thapsigargin, an SR Ca(2+)-ATPase inhibitor also attenuated Ca(2+) waves, pressure-induced constriction and MLC(20) phosphorylation. The SR-driven component of the myogenic response was proportionally greater at lower intravascular pressures and subsequent MYPT1 phosphorylation measures revealed that SR Ca(2+) waves facilitated pressure-induced MLC(20) phosphorylation through mechanisms that include myosin light chain phosphatase inhibition. Cumulatively, our findings show that mechanical stimuli augment Ca(2+) wave generation in arterial smooth muscle and that these transient events facilitate tone development particularly at lower intravascular pressures by providing a proportion of the Ca(2+) required to directly control MLC(20) phosphorylation.
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Affiliation(s)
- Rania E Mufti
- Hotchkiss Brain Institute, Libin Cardiovascular Institute, Department of Physiology & Pharmacology, University of Calgary, Alberta, Canada
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Jiang D, Jones PP, Davis DR, Gow R, Green MS, Birnie DH, Chen SRW, Gollob MH. Characterization of a novel mutation in the cardiac ryanodine receptor that results in catecholaminergic polymorphic ventricular tachycardia. Channels (Austin) 2010; 4:302-10. [PMID: 20676041 DOI: 10.4161/chan.4.4.12666] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an arrhythmogenic disease that manifests as syncope or sudden death during high adrenergic tone in the absence of structural heart defects. It is primarily caused by mutations in the cardiac ryanodine receptor (RyR2). The mechanism by which these mutations cause arrhythmia remains controversial, with discrepant findings related to the role of the RyR2 binding protein FKBP12.6. The purpose of this study was to characterize a novel RyR2 mutation identified in a kindred with clinically diagnosed CPVT. Single-strand conformational polymorphism analysis and direct DNA sequencing were used to screen the RyR2 gene for mutations. Site-directed mutagenesis was employed to introduce the mutation into the mouse RyR2 cDNA. The impact of the mutation on the interaction between RyR2 and a 12.6 kDa FK506 binding protein (FKBP12.6) was determined by immunoprecipitation and immunoblotting and its effect on RyR2 function was characterized by single cell Ca(2+) imaging and [(3)H]ryanodine binding. A novel CPVT mutation, E189D, was identified. The E189D mutation does not alter the affinity of the channel for FKBP12.6, but it increases the propensity for store-overload-induced Ca(2+) release (SOICR). Furthermore, the E189D mutation enhances the basal channel activity of RyR2 and its sensitivity to activation by caffeine. The E189D RyR2 mutation is causative for CPVT and functionally increases the propensity for SOICR without altering the affinity for FKBP12.6. These observations strengthen the notion that enhanced SOICR, but not altered FKBP12.6 binding, is a common mechanism by which RyR2 mutations cause arrhythmias.
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Affiliation(s)
- Dawei Jiang
- Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
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46
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Affiliation(s)
- Peter P Jones
- Department of Physiology and Biophysics, University of Calgary, Calgary, AB, CA
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47
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Jiang D, Chen W, Xiao J, Wang R, Kong H, Jones PP, Zhang L, Fruen B, Chen SRW. Reduced threshold for luminal Ca2+ activation of RyR1 underlies a causal mechanism of porcine malignant hyperthermia. J Biol Chem 2008; 283:20813-20. [PMID: 18505726 DOI: 10.1074/jbc.m801944200] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Naturally occurring mutations in the skeletal muscle Ca(2+) release channel/ryanodine receptor RyR1 are linked to malignant hyperthermia (MH), a life-threatening complication of general anesthesia. Although it has long been recognized that MH results from uncontrolled or spontaneous Ca(2+) release from the sarcoplasmic reticulum, how MH RyR1 mutations render the sarcoplasmic reticulum susceptible to volatile anesthetic-induced spontaneous Ca(2+) release is unclear. Here we investigated the impact of the porcine MH mutation, R615C, the human equivalent of which also causes MH, on the intrinsic properties of the RyR1 channel and the propensity for spontaneous Ca(2+) release during store Ca(2+) overload, a process we refer to as store overload-induced Ca(2+) release (SOICR). Single channel analyses revealed that the R615C mutation markedly enhanced the luminal Ca(2+) activation of RyR1. Moreover, HEK293 cells expressing the R615C mutant displayed a reduced threshold for SOICR compared with cells expressing wild type RyR1. Furthermore, the MH-triggering agent, halothane, potentiated the response of RyR1 to luminal Ca(2+) and SOICR. Conversely, dantrolene, an effective treatment for MH, suppressed SOICR in HEK293 cells expressing the R615C mutant, but not in cells expressing an RyR2 mutant. These data suggest that the R615C mutation confers MH susceptibility by reducing the threshold for luminal Ca(2+) activation and SOICR, whereas volatile anesthetics trigger MH by further reducing the threshold, and dantrolene suppresses MH by increasing the SOICR threshold. Together, our data support a view in which altered luminal Ca(2+) regulation of RyR1 represents a primary causal mechanism of MH.
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Affiliation(s)
- Dawei Jiang
- Libin Cardiovascular Institutes of Alberta, Department of Physiology, University of Calgary, Calgary, Alberta, Canada
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Xiao J, Tian X, Jones PP, Bolstad J, Kong H, Wang R, Zhang L, Duff HJ, Gillis AM, Fleischer S, Kotlikoff M, Copello JA, Chen SRW. Removal of FKBP12.6 does not alter the conductance and activation of the cardiac ryanodine receptor or the susceptibility to stress-induced ventricular arrhythmias. J Biol Chem 2007; 282:34828-38. [PMID: 17921453 DOI: 10.1074/jbc.m707423200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 12.6-kDa FK506-binding protein (FKBP12.6) is considered to be a key regulator of the cardiac ryanodine receptor (RyR2), but its precise role in RyR2 function is complex and controversial. In the present study we investigated the impact of FKBP12.6 removal on the properties of the RyR2 channel and the propensity for spontaneous Ca(2+) release and the occurrence of ventricular arrhythmias. Single channel recordings in lipid bilayers showed that FK506 treatment of recombinant RyR2 co-expressed with or without FKBP12.6 or native canine RyR2 did not induce long-lived subconductance states. [(3)H]Ryanodine binding studies revealed that coexpression with or without FKBP12.6 or treatment with or without FK506 did not alter the sensitivity of RyR2 to activation by Ca(2+) or caffeine. Furthermore, single cell Ca(2+) imaging analyses demonstrated that HEK293 cells co-expressing RyR2 and FKBP12.6 or expressing RyR2 alone displayed the same propensity for spontaneous Ca(2+) release or store overload-induced Ca(2+) release (SOICR). FK506 increased the amplitude and decreased the frequency of SOICR in HEK293 cells expressing RyR2 with or without FKBP12.6, indicating that the action of FK506 on SOICR is independent of FKBP12.6. As with recombinant RyR2, the conductance and ligand-gating properties of single RyR2 channels from FKBP12.6-null mice were indistinguishable from those of single wild type channels. Moreover, FKBP12.6-null mice did not exhibit enhanced susceptibility to stress-induced ventricular arrhythmias, in contrast to previous reports. Collectively, our results demonstrate that the loss of FKBP12.6 has no significant effect on the conduction and activation of RyR2 or the propensity for spontaneous Ca(2+) release and stress-induced ventricular arrhythmias.
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Affiliation(s)
- Jianmin Xiao
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Biophysics, University of Calgary, Calgary, AB, T2N 4N1, Canada
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Xiao B, Tian X, Xie W, Jones PP, Cai S, Wang X, Jiang D, Kong H, Zhang L, Chen K, Walsh MP, Cheng H, Chen SRW. Functional consequence of protein kinase A-dependent phosphorylation of the cardiac ryanodine receptor: sensitization of store overload-induced Ca2+ release. J Biol Chem 2007; 282:30256-64. [PMID: 17693412 DOI: 10.1074/jbc.m703510200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The phosphorylation of the cardiac Ca(2+)-release channel (ryanodine receptor, RyR2) by protein kinase A (PKA) has been extensively characterized, but its functional consequence remains poorly defined and controversial. We have previously shown that RyR2 is phosphorylated by PKA at two major sites, serine 2,030 and serine 2,808, of which Ser-2,030 is the major PKA site responding to beta-adrenergic stimulation. Here we investigated the effect of the phosphorylation of RyR2 by PKA on the properties of single channels and on spontaneous Ca(2+) release during sarcoplasmic reticulum Ca(2+) overload, a process we have referred to as store overload-induced Ca(2+) release (SOICR). We found that PKA activated single RyR2 channels in the presence, but not in the absence, of luminal Ca(2+). On the other hand, PKA had no marked effect on the sensitivity of the RyR2 channel to activation by cytosolic Ca(2+). Importantly, the S2030A mutation, but not mutations of Ser-2,808, diminished the effect of PKA on RyR2. Furthermore, a phosphomimetic mutation, S2030D, potentiated the response of RyR2 to luminal Ca(2+) and enhanced the propensity for SOICR in HEK293 cells. In intact rat ventricular myocytes, the activation of PKA by isoproterenol reduced the amplitude and increased the frequency of SOICR. Confocal line-scanning fluorescence microscopy further revealed that the activation of PKA by isoproterenol increased the rate of Ca(2+) release and the propagation velocity of spontaneous Ca(2+) waves, despite reduced wave amplitude and resting cytosolic Ca(2+). Collectively, our data indicate that PKA-dependent phosphorylation enhances the response of RyR2 to luminal Ca(2+) and reduces the threshold for SOICR and that this effect of PKA is largely mediated by phosphorylation at Ser-2,030.
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Affiliation(s)
- Bailong Xiao
- Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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50
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Jones PP, Bazzazi H, Kargacin GJ, Colyer J. Inhibition of cAMP-dependent protein kinase under conditions occurring in the cardiac dyad during a Ca2+ transient. Biophys J 2006; 91:433-43. [PMID: 16632511 PMCID: PMC1483070 DOI: 10.1529/biophysj.106.083931] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The space between the t-tubule invagination and the sarcoplasmic reticulum (SR) membrane, the dyad, in ventricular myocytes has been predicted to experience very high [Ca2+] for short periods of time during a Ca2+ transient. The dyadic space accommodates many protein kinases responsible for the regulation of Ca2+ handling proteins of the cell. We show in vitro that cAMP-dependent protein kinase (PKA) is inhibited by high [Ca2+] through a shift in the ratio of CaATP/MgATP toward CaATP. We further generate a three-dimensional mathematical model of Ca2+ and ATP diffusion within dyad. We use this model to predict the extent to which PKA would be inhibited by an increased CaATP/MgATP ratio during a Ca2+ transient in the dyad in vivo. Our results suggest that under normal physiological conditions a myocyte paced at 1 Hz would experience up to 55% inhibition of PKA within the cardiac dyad, with inhibition averaging 5% throughout the transient, an effect which becomes more pronounced as the myocyte contractile frequency increases (at 7 Hz, PKA inhibition averages 28% across the dyad throughout the duration of a Ca2+ transient).
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Affiliation(s)
- Peter P Jones
- Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
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