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Lakin R, Liu X, Chen W, Debi R, Yakobov S, Polidovitch N, Backx P. TARGETING TUMOR NECROSIS FACTOR (TNF) IN ATRIAL STRETCH-DEPENDENT ADVERSE ATRIAL REMODELING AND VALVULAR ATRIAL FIBRILLATION IN A MOUSE MODEL OF AORTIC REGURGITATION. Can J Cardiol 2022. [DOI: 10.1016/j.cjca.2022.08.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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2
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Teng A, Gu L, Di Paola M, Lakin R, Williams Z, Au A, CHEN WENLIANG, Callaghan NI, Hakem Zadeh F, ZHOU YUQING, Fatah M, Chatterjee D, Jourdan J, Jack L, Simmons CA, Kislinger T, Yip C, Backx P, Gourdie RG, Hamilton RM, Gramolini A. Abstract P2018: Tmem65 Is Critical For The Structure And Function Of The Intercalated Discs In Mouse Hearts. Circ Res 2022. [DOI: 10.1161/res.131.suppl_1.p2018] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The intercalated disc (ICD) is unique membrane structure that is indispensable to normal heart function, yet its structural organization is not completely understood. Previously, we showed that the ICD-bound transmembrane protein 65 (Tmem65) was required for connexin 43 (Cx43) localization and function in cultured mouse neonatal cardiomyocytes. Here, we investigated the role of Tmem65 in ICD organization
in vivo
. A mouse model was established by injecting CD1 mouse pups (3-7 days after birth) with recombinant adeno-associated virus 9 (rAAV9) harboring Tmem65 shRNA which resulted in a 90% reduction of Tmem65 expression in mouse ventricles compared to mice injected with scrambled shRNA. Tmem65 knockdown (KD) resulted in increased mortality which was accompanied by eccentric hypertrophic cardiomyopathy within 3 weeks of injection, progressing to dilated cardiomyopathy with severe cardiac fibrosis by 7 weeks post-injection. Tmem65 KD hearts displayed depressed hemodynamics, measured echocardiographically, accompanied by electrocardiogram changes (prolonged PR intervals and QRS duration) consistent with impaired conduction, which was confirmed with optical mapping of isolated hearts. Immunoprecipitation and super-resolution microscopy demonstrated a physical interaction between Tmem65 and sodium channel β subunit (β1) in mouse hearts and this interaction appeared to be required for both the establishment of perinexal nanodomain structure and the localization of both voltage-gated sodium channel 1.5 (NaV1.5) and Cx43 to ICDs. Despite the loss of NaV1.5 at the ICDs, whole-cell patch clamp electrophysiology did not reveal reductions in Na
+
currents but did show reduced Ca
2+
and K
+
currents in Tmem65 KD cardiomyocytes in comparison to control cells. We conclude that disrupting Tmem65 function results in impaired ICD structure, abnormal cardiac electrophysiology, and ultimately cardiomyopathy.
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Affiliation(s)
| | | | | | | | | | - Aaron Au
- Univ of Toronto, Toronto, Canada
| | | | | | | | | | | | | | | | - Liu Jack
- Univ of Toronto, Toronto, Canada
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3
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Lakin R, Debi R, Polidovitch N, Chen W, Yakobov S, Backx P. ATRIAL STRETCH-DEPENDENT TUMOR NECROSIS FACTOR-MEDIATED ADVERSE ATRIAL REMODELING AND ATRIAL ARRHYTHMIA INDUCIBILITY IN A MOUSE MODEL OF AORTIC REGURGITATION. Can J Cardiol 2021. [DOI: 10.1016/j.cjca.2021.07.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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4
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Lakin R, Polidovitch N, Chen W, Yakobov S, Backx P. Atrial Stretch‐Dependent Tumor Necrosis Factor (TNF)‐Mediated Adverse Atrial Remodeling and Atrial Arrhythmia Inducibility in a Mouse Model of Aortic Regurgitation. FASEB J 2021. [DOI: 10.1096/fasebj.2021.35.s1.03805] [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]
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5
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Siraj MA, Mundil D, Beca S, Momen A, Shikatani EA, Afroze T, Sun X, Liu Y, Ghaffari S, Lee W, Wheeler MB, Keller G, Backx P, Husain M. Cardioprotective GLP-1 metabolite prevents ischemic cardiac injury by inhibiting mitochondrial trifunctional protein-α. J Clin Invest 2020; 130:1392-1404. [PMID: 31985487 DOI: 10.1172/jci99934] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 11/13/2019] [Indexed: 01/02/2023] Open
Abstract
Mechanisms mediating the cardioprotective actions of glucagon-like peptide 1 (GLP-1) were unknown. Here, we show in both ex vivo and in vivo models of ischemic injury that treatment with GLP-1(28-36), a neutral endopeptidase-generated (NEP-generated) metabolite of GLP-1, was as cardioprotective as GLP-1 and was abolished by scrambling its amino acid sequence. GLP-1(28-36) enters human coronary artery endothelial cells (caECs) through macropinocytosis and acts directly on mouse and human coronary artery smooth muscle cells (caSMCs) and caECs, resulting in soluble adenylyl cyclase Adcy10-dependent (sAC-dependent) increases in cAMP, activation of protein kinase A, and cytoprotection from oxidative injury. GLP-1(28-36) modulates sAC by increasing intracellular ATP levels, with accompanying cAMP accumulation lost in sAC-/- cells. We identify mitochondrial trifunctional protein-α (MTPα) as a binding partner of GLP-1(28-36) and demonstrate that the ability of GLP-1(28-36) to shift substrate utilization from oxygen-consuming fatty acid metabolism toward oxygen-sparing glycolysis and glucose oxidation and to increase cAMP levels is dependent on MTPα. NEP inhibition with sacubitril blunted the ability of GLP-1 to increase cAMP levels in coronary vascular cells in vitro. GLP-1(28-36) is a small peptide that targets novel molecular (MTPα and sAC) and cellular (caSMC and caEC) mechanisms in myocardial ischemic injury.
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Affiliation(s)
- M Ahsan Siraj
- Ted Rogers Centre for Heart Research, University of Toronto, Toronto, Ontario, Canada.,Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Dhanwantee Mundil
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Sanja Beca
- Heart and Stroke Richard Lewar Center of Excellence in Cardiovascular Research, and
| | - Abdul Momen
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Eric A Shikatani
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada.,Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Talat Afroze
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Xuetao Sun
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Ying Liu
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Siavash Ghaffari
- Keenan Research Centre for Biomedical Research, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Warren Lee
- Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.,Keenan Research Centre for Biomedical Research, St. Michael's Hospital, Toronto, Ontario, Canada.,Department of Biochemistry.,Department of Medicine, and
| | - Michael B Wheeler
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Gordon Keller
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.,McEwen Centre for Regenerative Medicine, and
| | - Peter Backx
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Mansoor Husain
- Ted Rogers Centre for Heart Research, University of Toronto, Toronto, Ontario, Canada.,Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Heart and Stroke Richard Lewar Center of Excellence in Cardiovascular Research, and.,Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.,Department of Medicine, and.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.,McEwen Centre for Regenerative Medicine, and.,Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada
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6
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Wauchop M, Gagliardi M, Rafatian N, Massé S, Lai P, Tung KC, Protze S, Wang E, Radisic M, Keller G, Nanthakumar K, Backx P. Pathophysiology of R222Q mutant SCN5a channels. J Mol Cell Cardiol 2018. [DOI: 10.1016/j.yjmcc.2018.07.027] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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7
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Lakin R, Polidovitch N, Yang S, Guzman C, Gao X, Backx P. Atrial arrhythmias and adverse atrial remodeling induced by exercise requires soluble tumor necrosis factor alpha (TNFα) derived from atrial myocardium. J Mol Cell Cardiol 2018. [DOI: 10.1016/j.yjmcc.2018.07.028] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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8
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Barichello S, Roberts JD, Backx P, Boyle PM, Laksman Z. Personalizing therapy for atrial fibrillation: the role of stem cell and in silico disease models. Cardiovasc Res 2018; 114:931-943. [DOI: 10.1093/cvr/cvy090] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Accepted: 04/06/2018] [Indexed: 11/12/2022] Open
Affiliation(s)
- Scott Barichello
- University of British Columbia, 2329 West Mall, Vancouver, BC V6T 1Z4, Canada
| | - Jason D Roberts
- Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, Western University, London, ON, Canada
| | | | - Patrick M Boyle
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University
| | - Zachary Laksman
- Division of Cardiology, University of British Columbia, 211-1033 Davie Street Vancouver, BC V6E 1M7, Canada
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Ronaldson K, Feric N, Zhao Y, Zhang B, Conant G, Panhke A, Aschar-Sobbi R, Vunjak-Novakovic G, Backx P, Radisic M. TARA Biosystems' Biowire TM II: Engineering Mature Human Cardiac Tissues Enables More Predictive Drug Screening. J Pharmacol Toxicol Methods 2017. [DOI: 10.1016/j.vascn.2017.09.240] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Xie L, Liang T, Kang Y, Lin X, Sobbi R, Xie H, Chao C, Backx P, Feng ZP, Shyng SL, Gaisano HY. Phosphatidylinositol 4,5-biphosphate (PIP2) modulates syntaxin-1A binding to sulfonylurea receptor 2A to regulate cardiac ATP-sensitive potassium (KATP) channels. J Mol Cell Cardiol 2014; 75:100-10. [DOI: 10.1016/j.yjmcc.2014.07.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 07/15/2014] [Accepted: 07/18/2014] [Indexed: 11/15/2022]
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11
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Sivagangabalan G, Nazzari H, Bignolais O, Maguy A, Naud P, Farid T, Massé S, Gaborit N, Varro A, Nair K, Backx P, Vigmond E, Nattel S, Demolombe S, Nanthakumar K. Regional ion channel gene expression heterogeneity and ventricular fibrillation dynamics in human hearts. PLoS One 2014; 9:e82179. [PMID: 24427266 PMCID: PMC3888386 DOI: 10.1371/journal.pone.0082179] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 10/22/2013] [Indexed: 01/25/2023] Open
Abstract
RATIONALE Structural differences between ventricular regions may not be the sole determinant of local ventricular fibrillation (VF) dynamics and molecular remodeling may play a role. OBJECTIVES To define regional ion channel expression in myopathic hearts compared to normal hearts, and correlate expression to regional VF dynamics. METHODS AND RESULTS High throughput real-time RT-PCR was used to quantify the expression patterns of 84 ion-channel, calcium cycling, connexin and related gene transcripts from sites in the LV, septum, and RV in 8 patients undergoing transplantation. An additional eight non-diseased donor human hearts served as controls. To relate local ion channel expression change to VF dynamics localized VF mapping was performed on the explanted myopathic hearts right adjacent to sampled regions. Compared to non-diseased ventricles, significant differences (p<0.05) were identified in the expression of 23 genes in the myopathic LV and 32 genes in the myopathic RV. Within the myopathic hearts significant regional (LV vs septum vs RV) expression differences were observed for 13 subunits: Nav1.1, Cx43, Ca3.1, Cavα2δ2, Cavβ2, HCN2, Na/K ATPase-1, CASQ1, CASQ2, RYR2, Kir2.3, Kir3.4, SUR2 (p<0.05). In a subset of genes we demonstrated differences in protein expression between control and myopathic hearts, which were concordant with the mRNA expression profiles for these genes. Variability in the expression of Cx43, hERG, Na(+)/K(+) ATPase ß1 and Kir2.1 correlated to variability in local VF dynamics (p<0.001). To better understand the contribution of multiple ion channel changes on VF frequency, simulations of a human myocyte model were conducted. These simulations demonstrated the complex nature by which VF dynamics are regulated when multi-channel changes are occurring simultaneously, compared to known linear relationships. CONCLUSIONS Ion channel expression profile in myopathic human hearts is significantly altered compared to normal hearts. Multi-channel ion changes influence VF dynamic in a complex manner not predicted by known single channel linear relationships.
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Affiliation(s)
| | | | - Olivier Bignolais
- INSERM, UMR915, l'institut du thorax, Nantes, France
- CNRS, ERL3147, Nantes, France
- Université de Nantes, Nantes, France
| | - Ange Maguy
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, Pessac, France
- Lab IMB, University Bordeaux 1, Talence, France
| | - Patrice Naud
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, Pessac, France
- Lab IMB, University Bordeaux 1, Talence, France
| | | | | | - Nathalie Gaborit
- INSERM, UMR915, l'institut du thorax, Nantes, France
- CNRS, ERL3147, Nantes, France
- Université de Nantes, Nantes, France
| | - Andras Varro
- University of Szeged and Division of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | | | | | - Edward Vigmond
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, Pessac, France
- Lab IMB, University Bordeaux 1, Talence, France
| | - Stanley Nattel
- Montreal Heart Institute (MHI) and Université de Montréal Faculty of Medicine, Montreal, Canada
| | - Sophie Demolombe
- INSERM, UMR915, l'institut du thorax, Nantes, France
- CNRS, ERL3147, Nantes, France
- Université de Nantes, Nantes, France
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Zamiri N, Massé S, Ramadeen A, Kusha M, Hu X, Azam MA, Liu J, Lai PFH, Vigmond EJ, Boyle PM, Behradfar E, Al-Hesayen A, Waxman MB, Backx P, Dorian P, Nanthakumar K. Dantrolene improves survival after ventricular fibrillation by mitigating impaired calcium handling in animal models. Circulation 2014; 129:875-85. [PMID: 24403563 DOI: 10.1161/circulationaha.113.005443] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [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: 11/16/2022]
Abstract
BACKGROUND Resistant ventricular fibrillation, refibrillation. and diminished myocardial contractility are important factors leading to poor survival after cardiac arrest. We hypothesized that dantrolene improves survival after ventricular fibrillation (VF) by rectifying the calcium dysregulation caused by VF. METHODS AND RESULTS VF was induced in 26 Yorkshire pigs for 4 minutes. Cardiopulmonary resuscitation was then commenced for 3 minutes, and dantrolene or isotonic saline was infused at the onset of cardiopulmonary resuscitation. Animals were defibrillated and observed for 30 minutes. To study the effect of VF on calcium handling and its modulation by dantrolene, hearts from 14 New Zealand rabbits were Langendorff-perfused. The inducibility of VF after dantrolene administration was documented. Optical mapping was performed to evaluate diastolic spontaneous calcium elevations as a measure of cytosolic calcium leak. The sustained return of spontaneous circulation (systolic blood pressure ≥60 mm Hg) was achieved in 85% of the dantrolene group in comparison with 39% of controls (P=0.02). return of spontaneous circulation was achieved earlier in dantrolene-treated pigs after successful defibrillation (21 ± 6 s versus 181 ± 57 s in controls, P=0.005). The median number of refibrillation episodes was lower in the dantrolene group (0 versus 1, P=0.04). In isolated rabbit hearts, the successful induction of VF was achieved in 83% of attempts in controls versus 41% in dantrolene-treated hearts (P=0.007). VF caused diastolic calcium leaks in the form of spontaneous calcium elevations. Administration of 20 μmol/L dantrolene significantly decreased spontaneous calcium elevation amplitude versus controls. (0.024 ± 0.013 versus 0.12 ± 0.02 arbitrary unit [200-ms cycle length], P=0.001). CONCLUSIONS Dantrolene infusion during cardiopulmonary resuscitation facilitates successful defibrillation, improves hemodynamics postdefibrillation, decreases refibrillation, and thus improves survival after cardiac arrest. The effects are mediated through normalizing VF-induced dysfunctional calcium cycling.
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Affiliation(s)
- Nima Zamiri
- From The Hull Family Cardiac Fibrillation Management Laboratory, University Health Network, University of Toronto, Toronto, ON, Canada (A.M., N.Z., S.M., M.K., M.A.A, P.F.H.L., M.B.W., K.N.); Keenan Research Centre, Li Ka Shing Knowledge Institute, St Michael's Hospital, Toronto, ON, Canada (A.R., X.H., A.A.-H., P.D.); Institute of Medical Science, University of Toronto, Toronto, ON, Canada (N.Z.); Department of Physiology, University of Toronto, Toronto, ON, Canada (J.L., P.B.); Institute LIRYC, Université Bordeaux 1, Bordeaux, France (E.J.V.); Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD (P.M.B.); and Department of Electrical Engineering, University of Calgary, Calgary, AB, Canada (E.B.)
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13
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Ang R, Birnbaumer L, Gourine AV, Tinker A, Hamilton RM, Strandberg L, Cui X, Rath A, Liu J, Sirigam V, Ackerley C, Jaeggi E, Backx P, Silverman ED, Debney MT, Ng FS, Lyon AR, Peters NS, Opel A, Nobles M, Tinker A, Winter J, Chin SH, Brack KE, Ng GA, Finlay MC, Xu L, Nobles M, Lane J, Lowe M, Ben-Simon R, Bhar-Amato J, Hussain Q, Sebastian S, Taggart P, Tinker A, Lambiase PD, Almeida TP, Salinet J, Chu GS, Schlindwein FS, Ng GA, Williams SE, Linton NWF, Harrison J, Wright M, Plank G, O'Neill MD, Niederer S, Raine DT, Langley P, Shepherd E, Lord S, Murray S, Bourke JP, Chen Z, Hanson B, Sohal M, Child N, Sammut E, Jackson T, Shetty A, Bostock J, Gill J, Carr-White G, Rinaldi CA, Taggart P, Williams SE, Linton NW, Harrison J, Wright M, Rhode K, O'Neill MD, Barrows S, Jones K, Porter N. POSTER SESSION 2, HRC 2013. Europace 2013. [DOI: 10.1093/europace/eut320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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14
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Li G, de Couto G, Chen Y, Sun M, Shi Y, Heng Y, Dawood F, Liu Y, Zong Y, Khaper N, Backx P, McCulloch C, Liu P. The Critical Role of Autophagy in Iron-Overload Cardiomyopathy: A Model of Diastolic Heart Failure Due to Oxidative Stress. Can J Cardiol 2013. [DOI: 10.1016/j.cjca.2013.07.159] [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: 10/26/2022] Open
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15
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Kelsey L, Flenniken AM, Qu D, Funnell APW, Pearson R, Zhou YQ, Voronina I, Berberovic Z, Wood G, Newbigging S, Weiss ES, Wong M, Quach I, Yeh SYS, Deshwar AR, Scott IC, McKerlie C, Henkelman M, Backx P, Simpson J, Osborne L, Rossant J, Crossley M, Bruneau B, Adamson SL. ENU-induced mutation in the DNA-binding domain of KLF3 reveals important roles for KLF3 in cardiovascular development and function in mice. PLoS Genet 2013; 9:e1003612. [PMID: 23874215 PMCID: PMC3708807 DOI: 10.1371/journal.pgen.1003612] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 05/22/2013] [Indexed: 12/23/2022] Open
Abstract
KLF3 is a Krüppel family zinc finger transcription factor with widespread tissue expression and no previously known role in heart development. In a screen for dominant mutations affecting cardiovascular function in N-ethyl-N-nitrosourea (ENU) mutagenized mice, we identified a missense mutation in the Klf3 gene that caused aortic valvular stenosis and partially penetrant perinatal lethality in heterozygotes. All homozygotes died as embryos. In the first of three zinc fingers, a point mutation changed a highly conserved histidine at amino acid 275 to arginine (Klf3H275R). This change impaired binding of the mutant protein to KLF3's canonical DNA binding sequence. Heterozygous Klf3H275R mutants that died as neonates had marked biventricular cardiac hypertrophy with diminished cardiac chambers. Adult survivors exhibited hypotension, cardiac hypertrophy with enlarged cardiac chambers, and aortic valvular stenosis. A dominant negative effect on protein function was inferred by the similarity in phenotype between heterozygous Klf3H275R mutants and homozygous Klf3 null mice. However, the existence of divergent traits suggested the involvement of additional interactions. We conclude that KLF3 plays diverse and important roles in cardiovascular development and function in mice, and that amino acid 275 is critical for normal KLF3 protein function. Future exploration of the KLF3 pathway provides a new avenue for investigating causative factors contributing to cardiovascular disorders in humans. Cardiac defects are among the most common malformations in humans. Most causative genetic mutations remain unknown. To discover new causative genes important in cardiovascular development and function, we examined 1770 mice with randomly mutated genes and found a mutant with aortic valvular stenosis, and increased risk of fetal and neonatal death. Using linkage analysis and sequencing, we identified a protein-altering point mutation in the gene regulatory protein KLF3. Mice that survived into adulthood with one mutant copy of the Klf3 gene had low arterial blood pressure, enlarged hearts, and increased mortality due to heart failure. When both copies of the Klf3 gene was mutant, then embryos had heart defects, and all died before birth. KLF3 had no previously known role in heart development so to confirm these findings, we (1) knocked down klf3 expression in zebrafish embryos and (2) examined mice with a mutation that effectively eliminated the KLF3 protein. In both cases, cardiovascular dysfunction was observed. In conclusion, we have discovered that KLF3 plays diverse and important roles in cardiovascular development and function in mice. Future exploration of the KLF3 pathway provides a new avenue for investigating causative factors contributing to cardiovascular disorders in humans.
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Affiliation(s)
- Lois Kelsey
- Samuel Lunenfeld Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
- Centre for Modeling Human Disease, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
| | - Ann M. Flenniken
- Samuel Lunenfeld Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
- Centre for Modeling Human Disease, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
| | - Dawei Qu
- Samuel Lunenfeld Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
- Centre for Modeling Human Disease, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
| | - Alister P. W. Funnell
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Richard Pearson
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Yu-Qing Zhou
- Mouse Imaging Centre, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
- The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Irina Voronina
- Samuel Lunenfeld Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
- Centre for Modeling Human Disease, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
| | - Zorana Berberovic
- Samuel Lunenfeld Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
- Centre for Modeling Human Disease, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
| | - Geoffrey Wood
- Centre for Modeling Human Disease, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
- The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Susan Newbigging
- Centre for Modeling Human Disease, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
- The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Edward S. Weiss
- Centre for Modeling Human Disease, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
| | - Michael Wong
- Mouse Imaging Centre, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
- The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Ivan Quach
- Samuel Lunenfeld Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
| | - S. Y. Sandy Yeh
- Samuel Lunenfeld Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Ashish R. Deshwar
- The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Ian C. Scott
- The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- Heart and Stroke Richard Lewar Centre of Excellence, Toronto, Ontario, Canada
| | - Colin McKerlie
- Centre for Modeling Human Disease, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
- The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Mark Henkelman
- Mouse Imaging Centre, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
- The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Peter Backx
- Heart and Stroke Richard Lewar Centre of Excellence, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Jeremy Simpson
- Heart and Stroke Richard Lewar Centre of Excellence, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Lucy Osborne
- Centre for Modeling Human Disease, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Janet Rossant
- Centre for Modeling Human Disease, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
- The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Merlin Crossley
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Benoit Bruneau
- Gladstone Institute of Cardiovascular Disease, Department of Pediatrics, and Cardiovascular Research Institute, University of California, San Francisco, California, United States of America
| | - S. Lee Adamson
- Samuel Lunenfeld Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
- Centre for Modeling Human Disease, Toronto Centre for Phenogenomics, Toronto, Ontario, Canada
- Heart and Stroke Richard Lewar Centre of Excellence, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Obstetrics and Gynaecology, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Abbasi C, Wang D, El-Rass S, Li J, Backx P, Cox B, Wen X, Gramolini A. 375 ERp44 Expression During Zebrafish and Mouse Embryogenesis and Heart Development. Can J Cardiol 2012. [DOI: 10.1016/j.cjca.2012.07.353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Papp S, Dziak E, Kabir G, Backx P, Clement S, Opas M. Evidence for calreticulin attenuation of cardiac hypertrophy induced by pressure overload and soluble agonists. Am J Pathol 2010; 176:1113-21. [PMID: 20110410 DOI: 10.2353/ajpath.2010.090392] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
While calreticulin has been shown to be critical for cardiac development, its role in cardiac pathology is unclear. Previous studies have shown the detrimental effects on the heart of sustained germline calreticulin overexpression, yet without calreticulin, the heart does not develop normally. Thus, carefully balanced calreticulin levels are required for the heart to develop and to function properly into adulthood. But what happens to calreticulin levels, and how is this regulated, during cardiac hypertrophy, during which the fetal gene program is reactivated, at least partially? Our working hypothesis was that c-Src, a kinase whose activity we previously found to be correlated with calreticulin expression, was involved with calreticulin in regulating the response to hypertrophic signals. Thus, we subjected adult mice to transverse aortic constriction to induce left ventricular hypertrophy. We found that aortic constriction caused calreticulin levels to increase, whereas those of c-Src fell with longer constriction time. We also examined the ability of embryonic stem cell-derived cardiomyocytes to respond to soluble hypertrophic agonists. Endothelin-1 treatment caused a significantly greater cell area increase of calreticulin-null cardiomyocytes, which had higher c-Src activity, compared with wild-type cells. c-Src inhibition abolished this difference. Greater c-Src activity may explain the efficacy with which calreticulin-null cells are able to induce the hypertrophic program, while cells containing calreticulin may be able to attenuate the hypertrophic response as a result of decreased c-Src activity. Thus, calreticulin may have a protective effect on the heart in the face of cardiac hypertrophy.
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Affiliation(s)
- Sylvia Papp
- Department of Laboratory Medicine and Pathobiology, University of Toronto, 1 King's College Circle, Medical Sciences Building, Room 6326, Toronto, Ontario, M5S 1A8 Canada
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Cifelli C, Zhang H, Rose RA, Backx P, Heximer S. RGS4 attenuates parasympathetic signaling in the sinoatrial node: implications for heart rate regulation. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1044.11] [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)
| | | | | | - Peter Backx
- PhysiologyUniversity of TorontoTorontoCanada
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Zhu Y, Gramolini A, Takeuchi J, Zhou Y, Kranias L, Olson E, Henkelman R, Backx P, MacLennan D, Bruneau B. O127 Increased Serca2a activity can rescue ventricular diastolic dysfunction which is caused by deletion of Tbx5. Int J Cardiol 2008. [DOI: 10.1016/s0167-5273(08)70210-9] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Affiliation(s)
- K.-H. Kim
- Univ of Toronto, Toronto, ON, Canada
| | - P. Backx
- Univ of Toronto, Toronto, ON, Canada
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Ricci R, Eriksson U, Oudit GY, Eferl R, Akhmedov A, Sumara I, Sumara G, Kassiri Z, David JP, Bakiri L, Sasse B, Idarraga MH, Rath M, Kurz D, Theussl HC, Perriard JC, Backx P, Penninger JM, Wagner EF. Distinct functions of junD in cardiac hypertrophy and heart failure. Genes Dev 2005; 19:208-13. [PMID: 15655111 PMCID: PMC545879 DOI: 10.1101/gad.327005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cardiac hypertrophic stimuli induce both adaptive and maladaptive growth response pathways in heart. Here we show that mice lacking junD develop less adaptive hypertrophy in heart after mechanical pressure overload, while cardiomyocyte-specific expression of junD in mice results in spontaneous ventricular dilation and decreased contractility. In contrast, fra-1 conditional knock-out mice have a normal hypertrophic response, whereas hearts from fra-1 transgenic mice decompensate prematurely. Moreover, fra-1 transgenic mice simultaneously lacking junD reveal a spontaneous dilated cardiomyopathy associated with increased cardiomyocyte apoptosis and a primary mitochondrial defect. These data suggest that junD promotes both adaptive-protective and maladaptive hypertrophy in heart, depending on its expression levels.
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Affiliation(s)
- Romeo Ricci
- Institute of Molecular Pathology, A-1030 Vienna, Austria
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Tata N, Martino T, Ralph M, Arab S, Belsham D, Cukerman E, Tsui P, Straume M, Dawood F, Liu P, Backx P, Husain M, Sole M. Day/Night molecular rhythms in normal and diseased murine aorta. J Card Fail 2004. [DOI: 10.1016/j.cardfail.2004.06.070] [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: 10/26/2022]
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Backx P, Goldman S. Water/water-d2 solubility isotope effects. An estimate of the extent of nonclassical rotational behavior of water, when dissolved in benzene or carbon tetrachloride. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j150620a026] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Backx P, Goldman S. Hydrophobic clustering and a test of the excluded-volume theory of conformational stability in solution. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100347a089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Yazdanpanah M, Oudit G, Lee A, Dawood F, Wen WH, Backx P, Liu P. Cytotoxic aldehydes aggravate ventricular dysfunction in an injured heart: evidence from an iron overload model of heart failure. J Am Coll Cardiol 2002. [DOI: 10.1016/s0735-1097(02)80775-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Edwards L, Nashmi R, Jones O, Backx P, Ackerley C, Becker L, Fehlings MG. Upregulation of Kv 1.4 protein and gene expression after chronic spinal cord injury. J Comp Neurol 2002; 443:154-67. [PMID: 11793353 DOI: 10.1002/cne.10115] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [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: 11/05/2022]
Abstract
After spinal cord injury (SCI), white matter tracts are characterized by demyelination and increased sensitivity to the K(+) channel blocker 4-aminopyridine (4-AP). These effects appear to contribute to neurological impairment after SCI, although the molecular changes in K(+) channel subunit expression remain poorly understood. We examined changes in gene expression of the 4-AP-sensitive voltage-gated K(+) channel Kv 1.4 after chronic SCI in the rat. Quantitative immunoblotting showed that Kv 1.4 protein was significantly increased at 6 weeks, but not at 1 week, after SCI in spinal cord white matter. Kv 1.4 was localized to astrocytes, oligodendrocytes, and oligodendrocyte progenitor cells but not to axons in both the normal and the injured spinal cord white matter. Because glial cells proliferate after SCI, we used immunogold electron microscopy to quantify Kv 1.4 protein in individual glial cells and found a sixfold increase of Kv 1.4 in cells of the oligodendrocyte lineage after chronic injury. Finally, quantitative in situ hybridization showed that Kv 1.4 mRNA was significantly upregulated in spinal cord white matter, but not gray matter, after SCI. In summary, we show that Kv 1.4 is expressed in glial cells and not in axons in the rat spinal cord white matter and that its expression is markedly increased in cells of the oligodendrocyte lineage after chronic SCI. Given that K(+) channels play a role in glial cell proliferation, cells exhibiting changes in Kv 1.4 expression may represent proliferating oligodendroglia in the chronically injured spinal cord.
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Affiliation(s)
- Lori Edwards
- Division of Neurosurgery, The Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada M5T 2S8
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Puley G, Dawood F, Wen WH, Hou D, Backx P, Sole MJ, Aitken K, Liu P. The effect of a novel cardioprotector AAA-135 on the morphology and function in a viral model of cardiomyopathy. J Card Fail 1998. [DOI: 10.1016/s1071-9164(98)90173-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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