1
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How to select the appropriate method(s) of cytotoxicity analysis of mammalian cells at biointerfaces: A tutorial. Biointerphases 2020; 15:031201. [DOI: 10.1116/6.0000136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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2
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Amgalan D, Garner TP, Pekson R, Jia XF, Yanamandala M, Paulino V, Liang FG, Corbalan JJ, Lee J, Chen Y, Karagiannis GS, Sanchez LR, Liang H, Narayanagari SR, Mitchell K, Lopez A, Margulets V, Scarlata M, Santulli G, Asnani A, Peterson RT, Hazan RB, Condeelis JS, Oktay MH, Steidl U, Kirshenbaum LA, Gavathiotis E, Kitsis RN. A small-molecule allosteric inhibitor of BAX protects against doxorubicin-induced cardiomyopathy. NATURE CANCER 2020; 1:315-328. [PMID: 32776015 PMCID: PMC7413180 DOI: 10.1038/s43018-020-0039-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 01/29/2020] [Indexed: 12/27/2022]
Abstract
Doxorubicin remains an essential component of many cancer regimens, but its use is limited by lethal cardiomyopathy, which has been difficult to target, owing to pleiotropic mechanisms leading to apoptotic and necrotic cardiac cell death. Here we show that BAX is rate-limiting in doxorubicin-induced cardiomyopathy and identify a small-molecule BAX inhibitor that blocks both apoptosis and necrosis to prevent this syndrome. By allosterically inhibiting BAX conformational activation, this compound blocks BAX translocation to mitochondria, thereby abrogating both forms of cell death. When co-administered with doxorubicin, this BAX inhibitor prevents cardiomyopathy in zebrafish and mice. Notably, cardioprotection does not compromise the efficacy of doxorubicin in reducing leukemia or breast cancer burden in vivo, primarily due to increased priming of mitochondrial death mechanisms and higher BAX levels in cancer cells. This study identifies BAX as an actionable target for doxorubicin-induced cardiomyopathy and provides a prototype small-molecule therapeutic.
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Affiliation(s)
- Dulguun Amgalan
- Department of Medicine, Albert Einstein College of Medicine, Bronx NY, USA
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Thomas P Garner
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Ryan Pekson
- Department of Medicine, Albert Einstein College of Medicine, Bronx NY, USA
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Xiaotong F Jia
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Mounica Yanamandala
- Department of Medicine, Albert Einstein College of Medicine, Bronx NY, USA
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
- Division of Cardiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Victor Paulino
- Department of Medicine, Albert Einstein College of Medicine, Bronx NY, USA
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Felix G Liang
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
| | - J Jose Corbalan
- Department of Medicine, Albert Einstein College of Medicine, Bronx NY, USA
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Jaehoon Lee
- Department of Medicine, Albert Einstein College of Medicine, Bronx NY, USA
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Yun Chen
- Department of Medicine, Albert Einstein College of Medicine, Bronx NY, USA
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
| | - George S Karagiannis
- Department of Anatomy & Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY, USA
- Integrated Imaging Program, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Luis Rivera Sanchez
- Department of Anatomy & Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Surgery, Montefiore Medical Center, Bronx, NY, USA
| | - Huizhi Liang
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Swathi-Rao Narayanagari
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Kelly Mitchell
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Andrea Lopez
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Victoria Margulets
- Departments of Physiology and Pathophysiology and Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Manitoba, Canada
| | - Marco Scarlata
- Department of Medicine, Albert Einstein College of Medicine, Bronx NY, USA
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Gaetano Santulli
- Department of Medicine, Albert Einstein College of Medicine, Bronx NY, USA
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Aarti Asnani
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- CardioVascular Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Randall T Peterson
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- College of Pharmacy, University of Utah, Salt Lake City, UT, USA
| | - Rachel B Hazan
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA
- Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - John S Condeelis
- Department of Anatomy & Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY, USA
- Integrated Imaging Program, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Surgery, Montefiore Medical Center, Bronx, NY, USA
- Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Maja H Oktay
- Department of Anatomy & Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY, USA
- Integrated Imaging Program, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA
- Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Ulrich Steidl
- Department of Medicine, Albert Einstein College of Medicine, Bronx NY, USA
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Lorrie A Kirshenbaum
- Departments of Physiology and Pathophysiology and Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Manitoba, Canada
| | - Evripidis Gavathiotis
- Department of Medicine, Albert Einstein College of Medicine, Bronx NY, USA.
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA.
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA.
- Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA.
| | - Richard N Kitsis
- Department of Medicine, Albert Einstein College of Medicine, Bronx NY, USA.
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, USA.
- Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, Bronx, NY, USA.
- Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY, USA.
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3
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Yeang C, Hasanally D, Que X, Hung MY, Stamenkovic A, Chan D, Chaudhary R, Margulets V, Edel AL, Hoshijima M, Gu Y, Bradford W, Dalton N, Miu P, Cheung DY, Jassal DS, Pierce GN, Peterson KL, Kirshenbaum LA, Witztum JL, Tsimikas S, Ravandi A. Reduction of myocardial ischaemia-reperfusion injury by inactivating oxidized phospholipids. Cardiovasc Res 2019; 115:179-189. [PMID: 29850765 PMCID: PMC6302283 DOI: 10.1093/cvr/cvy136] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 04/18/2018] [Accepted: 05/22/2018] [Indexed: 02/06/2023] Open
Abstract
Aims Myocardial ischaemia followed by reperfusion (IR) causes an oxidative burst resulting in cellular dysfunction. Little is known about the impact of oxidative stress on cardiomyocyte lipids and their role in cardiac cell death. Our goal was to identify oxidized phosphatidylcholine-containing phospholipids (OxPL) generated during IR, and to determine their impact on cell viability and myocardial infarct size. Methods and results OxPL were quantitated in isolated rat cardiomyocytes using mass spectrophotometry following 24 h of IR. Cardiomyocyte cell death was quantitated following exogenously added OxPL and in the absence or presence of E06, a 'natural' murine monoclonal antibody that binds to the PC headgroup of OxPL. The impact of OxPL on mitochondria in cardiomyocytes was also determined using cell fractionation and Bnip expression. Transgenic Ldlr-/- mice, overexpressing a single-chain variable fragment of E06 (Ldlr-/--E06-scFv-Tg) were used to assess the effect of inactivating endogenously generated OxPL in vivo on myocardial infarct size. Following IR in vitro, isolated rat cardiomyocytes showed a significant increase in the specific OxPLs PONPC, POVPC, PAzPC, and PGPC (P < 0.05 to P < 0.001 for all). Exogenously added OxPLs resulted in significant death of rat cardiomyocytes, an effect inhibited by E06 (percent cell death with added POVPC was 22.6 ± 4.14% and with PONPC was 25.3 ± 3.4% compared to 8.0 ± 1.6% and 6.4 ± 1.0%, respectively, with the addition of E06, P < 0.05 for both). IR increased mitochondrial content of OxPL in rat cardiomyocytes and also increased expression of Bcl-2 death protein 3 (Bnip3), which was inhibited in presence of E06. Notably cardiomyocytes with Bnip3 knock-down were protected against cytotoxic effects of OxPL. In mice exposed to myocardial IR in vivo, compared to Ldlr-/- mice, Ldlr-/--E06-scFv-Tg mice had significantly smaller myocardial infarct size normalized to area at risk (72.4 ± 21.9% vs. 47.7 ± 17.6%, P = 0.023). Conclusions OxPL are generated within cardiomyocytes during IR and have detrimental effects on cardiomyocyte viability. Inactivation of OxPL in vivo results in a reduction of infarct size.
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MESH Headings
- Animals
- Cell Death
- Cells, Cultured
- Disease Models, Animal
- Male
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mice, Inbred C57BL
- Mice, Knockout
- Mitochondria, Heart/metabolism
- Mitochondria, Heart/pathology
- Mitochondrial Proteins/genetics
- Mitochondrial Proteins/metabolism
- Myocardial Infarction/genetics
- Myocardial Infarction/metabolism
- Myocardial Infarction/pathology
- Myocardial Infarction/prevention & control
- Myocardial Reperfusion Injury/genetics
- Myocardial Reperfusion Injury/metabolism
- Myocardial Reperfusion Injury/pathology
- Myocardial Reperfusion Injury/prevention & control
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Oxidation-Reduction
- Oxidative Stress/drug effects
- Phospholipids/metabolism
- Rats, Sprague-Dawley
- Receptors, LDL/genetics
- Receptors, LDL/metabolism
- Signal Transduction
- Single-Chain Antibodies/genetics
- Single-Chain Antibodies/metabolism
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Affiliation(s)
- Calvin Yeang
- Division of Cardiovascular Diseases, Sulpizio Cardiovascular Center, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Devin Hasanally
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Xuchu Que
- Division of Endocrinology and Metabolism, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Ming-Yow Hung
- Division of Cardiology, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan
- Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei City, Taiwan
| | - Aleksandra Stamenkovic
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
| | - David Chan
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Rakesh Chaudhary
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Victoria Margulets
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Andrea L Edel
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Masahiko Hoshijima
- Division of Cardiovascular Diseases, Sulpizio Cardiovascular Center, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Yusu Gu
- Division of Cardiovascular Diseases, Sulpizio Cardiovascular Center, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - William Bradford
- Division of Cardiovascular Diseases, Sulpizio Cardiovascular Center, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Nancy Dalton
- Division of Cardiovascular Diseases, Sulpizio Cardiovascular Center, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Phuong Miu
- Division of Cardiovascular Diseases, Sulpizio Cardiovascular Center, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - David Yc Cheung
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Davinder S Jassal
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Grant N Pierce
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Kirk L Peterson
- Division of Cardiovascular Diseases, Sulpizio Cardiovascular Center, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Lorrie A Kirshenbaum
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Joseph L Witztum
- Division of Endocrinology and Metabolism, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Sotirios Tsimikas
- Division of Cardiovascular Diseases, Sulpizio Cardiovascular Center, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Amir Ravandi
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
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Abstract
After decades of believing the heart loses the ability to regenerate soon after birth, numerous studies are now reporting that the adult heart may indeed be capable of regeneration, although the magnitude of new cardiac myocyte formation varies greatly. While this debate has energized the field of cardiac regeneration and led to a dramatic increase in our understanding of cardiac growth and repair, it has left much confusion in the field as to the prospects of regenerating the heart. Studies applying modern techniques of genetic lineage tracing and carbon-14 dating have begun to establish limits on the amount of endogenous regeneration after cardiac injury, but the underlying cellular mechanisms of this regeneration remained unclear. These same studies have also revealed an astonishing capacity for cardiac repair early in life that is largely lost with adult differentiation and maturation. Regardless, this renewed focus on cardiac regeneration as a therapeutic goal holds great promise as a novel strategy to address the leading cause of death in the developed world.
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Affiliation(s)
- Yiqiang Zhang
- Center for Cardiovascular Biology, Institute for Stem Cell Research and Division of Cardiology, Departments of Medicine and Pathology, University of Washington, Seattle, Washington
| | - John Mignone
- Center for Cardiovascular Biology, Institute for Stem Cell Research and Division of Cardiology, Departments of Medicine and Pathology, University of Washington, Seattle, Washington
| | - W Robb MacLellan
- Center for Cardiovascular Biology, Institute for Stem Cell Research and Division of Cardiology, Departments of Medicine and Pathology, University of Washington, Seattle, Washington
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5
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Johnston JC, Haile A, Wang D, Ronnett G, Jones LC. Dexamethasone treatment alters function of adipocytes from a mesenchymal stromal cell line. Biochem Biophys Res Commun 2014; 451:473-9. [DOI: 10.1016/j.bbrc.2014.07.063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 07/14/2014] [Indexed: 11/17/2022]
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6
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Wang X, Bathina M, Lynch J, Koss B, Calabrese C, Frase S, Schuetz JD, Rehg JE, Opferman JT. Deletion of MCL-1 causes lethal cardiac failure and mitochondrial dysfunction. Genes Dev 2013; 27:1351-64. [PMID: 23788622 DOI: 10.1101/gad.215855.113] [Citation(s) in RCA: 160] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
MCL-1 is an essential BCL-2 family member that promotes the survival of multiple cellular lineages, but its role in cardiac muscle has remained unclear. Here, we report that cardiac-specific ablation of Mcl-1 results in a rapidly fatal, dilated cardiomyopathy manifested by a loss of cardiac contractility, abnormal mitochondria ultrastructure, and defective mitochondrial respiration. Strikingly, genetic ablation of both proapoptotic effectors (Bax and Bak) could largely rescue the lethality and impaired cardiac function induced by Mcl-1 deletion. However, while the overt consequences of Mcl-1 loss were obviated by combining with the loss of Bax and Bak, mitochondria from the Mcl-1-, Bax-, and Bak-deficient hearts still revealed mitochondrial ultrastructural abnormalities and displayed deficient mitochondrial respiration. Together, these data indicate that merely blocking cell death is insufficient to completely overcome the need for MCL-1 function in cardiomyocytes and suggest that in cardiac muscle, MCL-1 also facilitates normal mitochondrial function. These findings are important, as specific MCL-1-inhibiting therapeutics are being proposed to treat cancer cells and may result in unexpected cardiac toxicity.
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Affiliation(s)
- Xi Wang
- Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, TN 38163, USA
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7
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Mughal W, Dhingra R, Kirshenbaum LA. Striking a balance: autophagy, apoptosis, and necrosis in a normal and failing heart. Curr Hypertens Rep 2013; 14:540-7. [PMID: 23001875 DOI: 10.1007/s11906-012-0304-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Despite the progress that has been made over the past two decades in cardiovascular research, heart failure remains a major cause of morbidity and mortality worldwide. Insight into the cellular and molecular mechanisms that underlie the heart failure in individuals with ischemic heart disease have identified defects in cellular processes that govern autophagy, apoptosis and necrosis as a prevailing underlying cause. Indeed, programmed cell death of cardiac cells by apoptosis or necrosis is believed to involve the intrinsic mitochondrial pathway and/or extrinsic death receptor pathway by certain Bcl-2 family members as well as components of the TNFα signaling pathway. In this review, we discuss recent advances in the molecular signaling factors that govern cardiac cell fate under normal and disease conditions.
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Affiliation(s)
- Wajihah Mughal
- The Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Department of Physiology, University of Manitoba, Winnipeg, Canada
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8
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Gang H, Shaw J, Dhingra R, Davie JR, Kirshenbaum LA. Epigenetic regulation of canonical TNFα pathway by HDAC1 determines survival of cardiac myocytes. Am J Physiol Heart Circ Physiol 2013; 304:H1662-9. [PMID: 23585133 DOI: 10.1152/ajpheart.00093.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gene transcription is regulated by post-translation modifications. Histone deacetylases (HDACs) remove acetyl groups from histone and non-histone factors inhibiting transcription. Proinflammatory cytokines such as TNFα activate the canonical nuclear factor-κB (NF-κB) pathway. Earlier we established a cytoprotective role for NF-κB in the heart. Though a causal relationship for HDAC1 and NF-κB has been established, the impact of HDAC1 on TNFα signaling is unknown. Herein, we demonstrate that HDAC1 provides a molecular switch for determining cell survival in the TNFα pathway. In contrast to vehicle-treated control cells, TNFα-treated cells displayed a marked increase in NF-κB gene transcription. Notably, cells treated with TNFα were indistinguishable from vehicle controls cells with respect to viability. Interestingly, HDAC activity was reduced in cells treated with TNFα. Conversely, in the presence of HDAC1, NF-κB gene transcription by TNFα was repressed, resulting in mitochondrial perturbations and widespread cell death. Heterologous fusion proteins comprised of yeast Gal4 DNA binding domain fused in frame to the NF-κB p65 transactivation domain were preferentially repressed by HDAC1. Moreover, transcription mediated by Gal4VP16 protein from herpes virus was unaffected by HDAC1 in cardiac myocytes. Mutations that abrogate known catalytic activities of HDAC1, small interference RNA, or pharmacological inhibition of HDAC1 restored NF-κB signaling and suppressed cell death induced by TNFα. These data provide the first evidence for an obligate link between HDAC1 and canonical TNFα pathway for cell survival of cardiac myocytes.
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Affiliation(s)
- Hongying Gang
- The Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
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9
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Inhibition of human Nav1.5 sodium channels by strychnine and its analogs. Biochem Pharmacol 2011; 82:350-7. [DOI: 10.1016/j.bcp.2011.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 04/15/2011] [Accepted: 05/09/2011] [Indexed: 11/19/2022]
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10
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Laguens RP, Crottogini AJ. Cardiac regeneration: the gene therapy approach. Expert Opin Biol Ther 2009; 9:411-25. [DOI: 10.1517/14712590902806364] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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11
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Antagonism of E2F-1 regulated Bnip3 transcription by NF-kappaB is essential for basal cell survival. Proc Natl Acad Sci U S A 2008; 105:20734-9. [PMID: 19088195 DOI: 10.1073/pnas.0807735105] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The transcription factor E2F-1 drives proliferation and death, but the mechanisms that differentially regulate these divergent actions are poorly understood. The hypoxia-inducible death factor Bnip3 is an E2F-1 target gene and integral component of the intrinsic mitochondrial death pathway. The mechanisms that govern Bnip3 gene activity remain cryptic. Herein we show that the transcription factor NF-kappaB provides a molecular switch that determines whether E2F-1 signals proliferation or death under physiological conditions. We show under basal nonapoptotic conditions that NF-kappaB constitutively occupies and transcriptionally silences Bnip3 gene transcription by competing with E2F-1 for Bnip3 promoter binding. Conversely, in the absence of NF-kappaB, or during hypoxia when NF-kappaB abundance is reduced, basal Bnip3 gene transcription is activated by the unrestricted binding of E2F-1 to the Bnip3 promoter. Genetic knock-down of E2F-1 or retinoblastoma gene product over-expression in cardiac and human pancreatic cancer cells deficient for NF-kappaB signaling abrogated basal and hypoxia-inducible Bnip3 transcription. The survival kinase PI3K/Akt inhibited Bnip3 expression levels in cells in a manner dependent upon NF-kappaB activation. Hence, by way of example, we show that the transcriptional inhibition of E2F-1-dependent Bnip3 expression by NF-kappaB highlights a survival pathway that overrides the E2F-1 tumor suppressor program. Our data may explain more fundamentally how cells, by selectively inhibiting E2F-1-dependent death gene transcription, avert apoptosis down-stream of the retinoblastoma/E2F-1 cell cycle pathway.
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12
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Ebelt H, Zhang Y, Köhler K, Xu J, Gajawada P, Boettger T, Hollemann T, Müller-Werdan U, Werdan K, Braun T. Directed expression of dominant-negative p73 enables proliferation of cardiomyocytes in mice. J Mol Cell Cardiol 2008; 45:411-9. [DOI: 10.1016/j.yjmcc.2008.06.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 06/12/2008] [Accepted: 06/13/2008] [Indexed: 11/26/2022]
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13
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Weidman D, Shaw J, Bednarczyk J, Regula KM, Yurkova N, Zhang T, Aguilar F, Kirshenbaum LA. Dissecting apoptosis and intrinsic death pathways in the heart. Methods Enzymol 2008; 446:277-85. [PMID: 18603128 DOI: 10.1016/s0076-6879(08)01616-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023]
Abstract
The limited regenerative capacity of postnatal ventricular myocytes coupled with their meager ability for genetic manipulation has presented a major technical obstacle for deciphering apoptosis initiation and execution signals in the heart. In this report, we describe the technical approaches used to study the intrinsic death pathways in postnatal ventricular myocytes during acute hypoxic injury. Discussed are methods for hypoxia, recombinant adenovirus-mediated gene transfer, cellular viability assays using the vital dyes calcein acetomethoxyester and ethidium homodimer-1, analysis of nuclear morphology by use of Hoechst dye 33258, and assessment of the state of the mitochondrial permeability transition pore. Our work has established that hypoxia triggers perturbations to mitochondria consistent with loss of mitochondrial membrane potential, permeability transition pore opening, and apoptotic cell death by the intrinsic pathway.
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Affiliation(s)
- Danielle Weidman
- Department of Physiology, Faculty of Medicine University of Manitoba, Winnipeg, Manitoba R2H2A6
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14
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Ebelt H, Zhang Y, Kampke A, Xu J, Schlitt A, Buerke M, Müller-Werdan U, Werdan K, Braun T. E2F2 expression induces proliferation of terminally differentiated cardiomyocytes in vivo. Cardiovasc Res 2008; 80:219-26. [PMID: 18628254 DOI: 10.1093/cvr/cvn194] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS In previous experiments we have demonstrated that expression of the transcription factors E2F2 and E2F4 is sufficient to induce proliferation of isolated primary cardiomyocytes from newborn rats and mice. We now wanted to analyse whether E2F2 or E2F4 are also able to promote cell cycle progression of adult cardiomyocytes in vivo, which unlike cardiomyocytes from newborn rodents lack the ability to undergo cell proliferation. METHODS AND RESULTS E2F2 or E2F4 was expressed in hearts of mice at different developmental stages using adenoviral vectors. Effects regarding proliferation, hypertrophy, and apoptosis were analysed on histological sections, and quantitative assessment of cell cycle regulatory genes was performed by real-time PCR (polymerase chain reaction) and western blot. We found that both E2F2 and E2F4 can stimulate hypertrophic cell growth of cardiomyocytes. However, only directed expression of E2F2 but not of E2F4 was sufficient to induce proliferation of cardiomyocytes. Expression of E2F2 in vivo did not increase the percentage of apoptotic cardiomyocytes but down-regulated the expression of the pro-apoptotic genes caspase-6 and apaf-1. Further analysis of the cell cycle regulatory machinery revealed that expression of E2F2 caused a strong induction of cyclin A and E while the expression of cyclin-dependent kinase inhibitors (CKIs) such as p21 was not affected. CONCLUSION We conclude that a limited induction of cardiomyocyte cell proliferation can be achieved by E2F2-mediated stimulation of cyclin A and E expression without a reduction of CKIs.
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Affiliation(s)
- Henning Ebelt
- Department of Medicine III, University of Halle-Wittenberg, Ernst-Grube-Strasse 40, 06097 Halle, Germany.
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15
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Angelis E, Garcia A, Chan SS, Schenke-Layland K, Ren S, Goodfellow SJ, Jordan MC, Roos KP, White RJ, MacLellan WR. A cyclin D2-Rb pathway regulates cardiac myocyte size and RNA polymerase III after biomechanical stress in adult myocardium. Circ Res 2008; 102:1222-9. [PMID: 18420946 DOI: 10.1161/circresaha.107.163550] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Normally, cell cycle progression is tightly coupled to the accumulation of cell mass; however, the mechanisms whereby proliferation and cell growth are linked are poorly understood. We have identified cyclin (Cyc)D2, a G(1) cyclin implicated in mediating S phase entry, as a potential regulator of hypertrophic growth in adult post mitotic myocardium. To examine the role of CycD2 and its downstream targets, we subjected CycD2-null mice to mechanical stress. Hypertrophic growth in response to transverse aortic constriction was attenuated in CycD2-null compared with wild-type mice. Blocking the increase in CycD2 in response to hypertrophic agonists prevented phosphorylation of CycD2-target Rb (retinoblastoma gene product) in vitro, and mice deficient for Rb had potentiated hypertrophic growth. Hypertrophic growth requires new protein synthesis and transcription of tRNA genes by RNA polymerase (pol) III, which increases with hypertrophic signals. This load-induced increase in RNA pol III activity is augmented in Rb-deficient hearts. Rb binds and represses Brf-1 and TATA box binding protein (TBP), subunits of RNA pol III-specific transcription factor B, in adult myocardium under basal conditions. However, this association is disrupted in response to transverse aortic constriction. RNA pol III activity is unchanged in CycD2(-/-) myocardium after transverse aortic constriction, and there is no dissociation of TBP from Rb. These investigations identify an essential role for the CycD2-Rb pathway as a governor of cardiac myocyte enlargement in response to biomechanical stress and, more fundamentally, as a regulator of the load-induced activation of RNA pol III.
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Affiliation(s)
- Ekaterini Angelis
- The Cardiovascular Research Laboratory, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095-1760, USA
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16
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Cardiomyocyte death and renewal in the normal and diseased heart. Cardiovasc Pathol 2008; 17:349-74. [PMID: 18402842 DOI: 10.1016/j.carpath.2008.02.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Revised: 11/30/2007] [Accepted: 02/04/2008] [Indexed: 02/07/2023] Open
Abstract
During post-natal maturation of the mammalian heart, proliferation of cardiomyocytes essentially ceases as cardiomyocytes withdraw from the cell cycle and develop blocks at the G0/G1 and G2/M transition phases of the cell cycle. As a result, the response of the myocardium to acute stress is limited to various forms of cardiomyocyte injury, which can be modified by preconditioning and reperfusion, whereas the response to chronic stress is dominated by cardiomyocyte hypertrophy and myocardial remodeling. Acute myocardial ischemia leads to injury and death of cardiomyocytes and nonmyocytic stromal cells by oncosis and apoptosis, and possibly by a hybrid form of cell death involving both pathways in the same ischemic cardiomyocytes. There is increasing evidence for a slow, ongoing turnover of cardiomyocytes in the normal heart involving death of cardiomyocytes and generation of new cardiomyocytes. This process appears to be accelerated and quantitatively increased as part of myocardial remodeling. Cardiomyocyte loss involves apoptosis, autophagy, and oncosis, which can occur simultaneously and involve different individual cardiomyocytes in the same heart undergoing remodeling. Mitotic figures in myocytic cells probably represent maturing progeny of stem cells in most cases. Mitosis of mature cardiomyocytes that have reentered the cell cycle appears to be a rare event. Thus, cardiomyocyte renewal likely is mediated primarily by endogenous cardiac stem cells and possibly by blood-born stem cells, but this biological phenomenon is limited in capacity. As a consequence, persistent stress leads to ongoing remodeling in which cardiomyocyte death exceeds cardiomyocyte renewal, resulting in progressive heart failure. Intense investigation currently is focused on cell-based therapies aimed at retarding cardiomyocyte death and promoting myocardial repair and possibly regeneration. Alteration of pathological remodeling holds promise for prevention and treatment of heart failure, which is currently a major cause of morbidity and mortality and a major public health problem. However, a deeper understanding of the fundamental biological processes is needed in order to make lasting advances in clinical therapeutics in the field.
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17
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Yurkova N, Shaw J, Blackie K, Weidman D, Jayas R, Flynn B, Kirshenbaum LA. The Cell Cycle Factor E2F-1 Activates Bnip3 and the Intrinsic Death Pathway in Ventricular Myocytes. Circ Res 2008; 102:472-9. [DOI: 10.1161/circresaha.107.164731] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The cell cycle factor E2F-1 is known to regulate a variety of cellular processes including apoptosis. Previously we showed that disruption of Rb–E2F-1 complexes provoked apoptosis of postmitotic adult and neonatal ventricular myocytes; however, the underlying mechanism was undetermined. In this report, we show that E2F-1 provokes cell death of ventricular myocytes through a mechanism that directly impinges on the intrinsic death pathway. Furthermore, we show mechanistically that the hypoxia-inducible death factor Bnip3 is a direct transcriptional target of E2F-1 that is necessary and sufficient for E2F-1–induced cell death. Expression of E2F-1 resulted in a 4.9-fold increase (
P
<0.001) in nucleosomal DNA fragmentation and cell death by Hoechst 33258 dye and vital staining. E2F-1 provoked mitochondrial perturbations that were consistent with permeability transition pore opening. As determined by quantitative real-time PCR analysis, a 6.2-fold increase (
P
<0.001) in endogenous Bnip3 gene transcription was observed in cells expressing wild-type E2F-1 but not in cells expressing a mutation of E2F-1 defective for DNA binding. Rb, the principle regulator of cellular E2F-1 activity, was proteolytically cleaved and inactivated in ventricular myocytes during hypoxia. Consistent with the proteolytic cleavage of Rb, chromatin immunoprecipitation analysis revealed increased binding of E2F-1 to the Bnip3 promoter during hypoxia, a finding concordant with the induction of Bnip3 gene transcription. The Bnip3 homolog Nix/Bnip3L was unaffected in ventricular myocytes by either E2F-1 or hypoxia. Genetic knockdown of E2F-1 or expression of a caspase-resistant form of Rb suppressed basal and hypoxia-inducible Bnip3 gene transcription. Loss-of-function mutations of Bnip3 defective for mitochondrial membrane insertion or small interference RNA directed against Bnip3 suppressed cell death signals elicited by E2F-1. To our knowledge, the data provide the first direct evidence that activation of the intrinsic mitochondrial death pathway by E2F-1 is mutually dependent on and obligatorily linked to the transcriptional activation of Bnip3.
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Affiliation(s)
- Natalia Yurkova
- From the Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Departments of Physiology (N.Y., K.B., D.W., R.J., B.F., L.A.K.), Pharmacology & Therapeutics (J.S., L.A.K.), Faculty of Medicine, University of Manitoba, Winnipeg, Canada
| | - James Shaw
- From the Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Departments of Physiology (N.Y., K.B., D.W., R.J., B.F., L.A.K.), Pharmacology & Therapeutics (J.S., L.A.K.), Faculty of Medicine, University of Manitoba, Winnipeg, Canada
| | - Karen Blackie
- From the Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Departments of Physiology (N.Y., K.B., D.W., R.J., B.F., L.A.K.), Pharmacology & Therapeutics (J.S., L.A.K.), Faculty of Medicine, University of Manitoba, Winnipeg, Canada
| | - Danielle Weidman
- From the Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Departments of Physiology (N.Y., K.B., D.W., R.J., B.F., L.A.K.), Pharmacology & Therapeutics (J.S., L.A.K.), Faculty of Medicine, University of Manitoba, Winnipeg, Canada
| | - Ravi Jayas
- From the Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Departments of Physiology (N.Y., K.B., D.W., R.J., B.F., L.A.K.), Pharmacology & Therapeutics (J.S., L.A.K.), Faculty of Medicine, University of Manitoba, Winnipeg, Canada
| | - Bryan Flynn
- From the Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Departments of Physiology (N.Y., K.B., D.W., R.J., B.F., L.A.K.), Pharmacology & Therapeutics (J.S., L.A.K.), Faculty of Medicine, University of Manitoba, Winnipeg, Canada
| | - Lorrie A. Kirshenbaum
- From the Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Departments of Physiology (N.Y., K.B., D.W., R.J., B.F., L.A.K.), Pharmacology & Therapeutics (J.S., L.A.K.), Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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18
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Morimoto T, Fujita M, Kawamura T, Sunagawa Y, Takaya T, Wada H, Shimatsu A, Kita T, Hasegawa K. Myocardial Regulation of p300 and p53 by Doxorubicin Involves Ubiquitin Pathways. Circ J 2008; 72:1506-11. [DOI: 10.1253/circj.cj-07-1076] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tatsuya Morimoto
- Division of Translational Research, Kyoto Medical Center, National Hospital Organization
| | - Masatoshi Fujita
- Department of Human Health Sciences, Graduate School of Medicine, Kyoto University
| | - Teruhisa Kawamura
- Division of Translational Research, Kyoto Medical Center, National Hospital Organization
| | - Yoichi Sunagawa
- Division of Translational Research, Kyoto Medical Center, National Hospital Organization
| | - Tomohide Takaya
- Division of Translational Research, Kyoto Medical Center, National Hospital Organization
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University
| | - Hiromichi Wada
- Division of Translational Research, Kyoto Medical Center, National Hospital Organization
| | - Akira Shimatsu
- Clinical Research Institute, Kyoto Medical Center, National Hospital Organization
| | - Toru Kita
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University
| | - Koji Hasegawa
- Division of Translational Research, Kyoto Medical Center, National Hospital Organization
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19
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Ahuja P, Sdek P, Maclellan WR. Cardiac myocyte cell cycle control in development, disease, and regeneration. Physiol Rev 2007; 87:521-44. [PMID: 17429040 PMCID: PMC2708177 DOI: 10.1152/physrev.00032.2006] [Citation(s) in RCA: 415] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cardiac myocytes rapidly proliferate during fetal life but exit the cell cycle soon after birth in mammals. Although the extent to which adult cardiac myocytes are capable of cell cycle reentry is controversial and species-specific differences may exist, it appears that for the vast majority of adult cardiac myocytes the predominant form of growth postnatally is an increase in cell size (hypertrophy) not number. Unfortunately, this limits the ability of the heart to restore function after any significant injury. Interest in novel regenerative therapies has led to the accumulation of much information on the mechanisms that regulate the rapid proliferation of cardiac myocytes in utero, their cell cycle exit in the perinatal period, and the permanent arrest (terminal differentiation) in adult myocytes. The recent identification of cardiac progenitor cells capable of giving rise to cardiac myocyte-like cells has challenged the dogma that the heart is a terminally differentiated organ and opened new prospects for cardiac regeneration. In this review, we summarize the current understanding of cardiomyocyte cell cycle control in normal development and disease. In addition, we also discuss the potential usefulness of cardiomyocyte self-renewal as well as feasibility of therapeutic manipulation of the cardiac myocyte cell cycle for cardiac regeneration.
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Affiliation(s)
| | | | - W. Robb Maclellan
- Corresponding author: W. Robb MacLellan, Cardiovascular Research Laboratories, David Geffen school of Medicine at UCLA, 675 C.E. Young Dr., MRL 3-645, Los Angeles, California, 90095-1760; Phone: (310) 825-2556; Fax: (310) 206-5777; e-mail:
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20
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Bicknell KA, Coxon CH, Brooks G. Can the cardiomyocyte cell cycle be reprogrammed? J Mol Cell Cardiol 2007; 42:706-21. [PMID: 17362983 DOI: 10.1016/j.yjmcc.2007.01.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Revised: 01/02/2007] [Accepted: 01/16/2007] [Indexed: 10/23/2022]
Abstract
Cardiac repair following myocardial injury is restricted due to the limited proliferative potential of adult cardiomyocytes. The ability of mammalian cardiomyocytes to proliferate is lost shortly after birth as cardiomyocytes withdraw from the cell cycle and differentiate. We do not fully understand the molecular and cellular mechanisms that regulate this cell cycle withdrawal, although if we could it might lead to the discovery of novel therapeutic targets for improving cardiac repair following myocardial injury. For the last decade, researchers have investigated cardiomyocyte cell cycle control, commonly using transgenic mouse models or recombinant adenoviruses to manipulate cell cycle regulators in vivo or in vitro. This review discusses cardiomyocyte cell cycle regulation and summarises recent data from studies manipulating the expressions and activities of cell cycle regulators in cardiomyocytes. The validity of therapeutic strategies that aim to reinstate the proliferative potential of cardiomyocytes to improve myocardial repair following injury will be discussed.
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Affiliation(s)
- Katrina A Bicknell
- School of Pharmacy, University of Reading, PO Box 226 Whiteknights, Reading Berkshire RG6 6AP, UK.
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21
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Cardiac Development: Toward a Molecular Basis for Congenital Heart Disease. CARDIOVASCULAR MEDICINE 2007. [DOI: 10.1007/978-1-84628-715-2_52] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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22
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Umezawa A, Toyoda M. Two MSCs: Marrow stromal cells and mesenchymal stem cells. Inflamm Regen 2007. [DOI: 10.2492/inflammregen.27.28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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23
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Shaw J, Zhang T, Rzeszutek M, Yurkova N, Baetz D, Davie JR, Kirshenbaum LA. Transcriptional Silencing of the Death Gene BNIP3 by Cooperative Action of NF-κB and Histone Deacetylase 1 in Ventricular Myocytes. Circ Res 2006; 99:1347-54. [PMID: 17082476 DOI: 10.1161/01.res.0000251744.06138.50] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Earlier we identified a survival role for NF-κB in ventricular myocytes, however, the underlying mechanism was undefined. In this report we provide new mechanistic evidence that the hypoxia-inducible death factor BNIP3 is transcriptionally silenced by NF-κB through a mechanism that involves the cooperative actions of HDAC1. Activation of the NF-κB signaling pathway in ventricular myocytes suppressed basal and hypoxia-inducible BNIP3 gene activity. Basal Bnip3 gene expression was increased in cells derived from p65
−/−
deficient mice. The histone deacetylase (HDAC) inhibitor Trichostatin A (TSA 10 nM) suppressed the inhibitory actions of NF-κB on Bnip3 gene transcription. Basal and hypoxia- induced Bnip3 transcription was repressed by wild type but not a catalytically inactive mutant of HDAC1. Immunoprecipitation assays verified interaction of HDAC1 with wild type p65 NF-κB and mutations of p65 defective for transactivation in ventricular myocytes. Deletion analysis revealed canonical NF-κB elements within the Bnip3 promoter to be important for repression of Bnip3 gene expression by HDAC1. Further, the ability of HDAC1 to repress Bnip3 gene transcription was lost in cells derived from p65
−/−
deficient mice but was restored by repletion of p65 NF-κB into p65
−/−
cells. Mutations of p65 NF-κB defective for DNA binding but not for transactivation abrogated the inhibitory actions of HDAC1 on the Bnip3 gene transcription. Together, our findings provide new mechanistic insight into the cytoprotective actions conferred by NF-κB that extend to the active transcriptional repression of the death factor Bnip3 through a mechanism that is mutually dependent on HDAC-1.
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Affiliation(s)
- James Shaw
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre Rm. 3016, 351 Taché Avenue, Winnipeg, Manitoba, Canada, R2H 2A6.
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24
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Ledda-Columbano GM, Molotzu F, Pibiri M, Cossu C, Perra A, Columbano A. Thyroid hormone induces cyclin D1 nuclear translocation and DNA synthesis in adult rat cardiomyocytes. FASEB J 2006; 20:87-94. [PMID: 16394271 DOI: 10.1096/fj.05-4202com] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Although mammalian cardiomyocytes lose their proliferative capacity after birth, there is evidence that postmitotic cardiomyocytes can proliferate provided that cyclin D1 accumulates in the nucleus. Here we show by Northern blot, Western analysis, and immunohistochemistry that 3,5,3'-triiodothyronine (T3) treatment of adult rats caused an increase of cyclin D1 mRNA and protein levels. The increased cyclin D1 protein content was associated with its translocation into the nucleus of cardiomyocytes. These changes were accompanied by the re-entry of cardiomyocytes into the cell cycle, as demonstrated by increased levels of cyclin A, PCNA, and incorporation of bromodeoxyuridine into DNA (labeling index was 30.2% in T3-treated rats vs. 2.2% in controls). Entry into the S phase was associated with an increased mitotic activity as demonstrated by positivity of cardiomyocyte nuclei to antibodies anti-phosphohistone-3, a specific marker of the mitotic phase (mitotic index was 3.01/1000 cardiomyocte nuclei in hyperthyroid rats vs. 0.04 in controls). No biochemical or histological signs of tissue damage were observed in the heart of T3-treated rats. These results demonstrated that T3 treatment is associated with a re-entry of cardiomyocytes into the cell cycle and so may be important for the development of future therapeutic strategies aimed at inducing proliferation of cardiomyocytes.
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25
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Zou MX, Roy AA, Zhao Q, Kirshenbaum LA, Karmazyn M, Chidiac P. RGS2 is upregulated by and attenuates the hypertrophic effect of alpha1-adrenergic activation in cultured ventricular myocytes. Cell Signal 2006; 18:1655-63. [PMID: 16517124 DOI: 10.1016/j.cellsig.2006.01.012] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2005] [Accepted: 01/11/2006] [Indexed: 11/24/2022]
Abstract
Regulator of G protein signaling (RGS) proteins counter the effects of G protein-coupled receptors (GPCRs) by limiting the abilities of G proteins to propagate signals, although little is known concerning their role in cardiac pathophysiology. We investigated the potential role of RGS proteins on alpha1-adrenergic receptor signals associated with hypertrophy in primary cultures of neonatal rat cardiomyocytes. Levels of mRNA encoding RGS proteins 1-5 were examined, and the alpha1-adrenergic agonist phenylephrine (PE) significantly increased RGS2 gene expression but had little or no effect on the others. The greatest changes in RGS2 mRNA occurred within the first hour of agonist addition. We next investigated the effects of RGS2 overexpression produced by infecting cells with an adenovirus encoding RGS2-cDNA on cardiomyocyte responses to PE. As expected, PE increased cardiomyocyte size and also significantly upregulated alpha-skeletal actin and ANP expression, the markers of hypertrophy, as well as the Na-H exchanger 1 isoform. These effects were blocked in cells infected with the adenovirus expressing RGS2. We also examined hypertrophy-associated MAP kinase pathways, and RGS2 overexpression completely prevented the activation of ERK by PE. In contrast, the activation of both JNK and p38 unexpectedly were increased by RGS2, although the ability of PE to further activate the p38 pathway was reduced. These results indicate that RGS2 is an important negative-regulatory factor in cardiac hypertrophy produced by alpha1-adrenergic receptor stimulation through complex mechanisms involving the modulation of mitogen-activated protein kinase signaling pathways.
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Affiliation(s)
- Min-Xu Zou
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada N6A 5C1
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26
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Baetz D, Regula KM, Ens K, Shaw J, Kothari S, Yurkova N, Kirshenbaum LA. Nuclear factor-kappaB-mediated cell survival involves transcriptional silencing of the mitochondrial death gene BNIP3 in ventricular myocytes. Circulation 2006; 112:3777-85. [PMID: 16344406 DOI: 10.1161/circulationaha.105.573899] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND A survival role for the transcription factor nuclear factor-kappaB (NF-kappaB) in ventricular myocytes has been reported; however, the underlying mechanism is undefined. In this report we provide new mechanistic evidence that survival signals conferred by NF-kappaB impinge on the hypoxia-inducible death factor BNIP3. METHODS AND RESULTS Activation of the NF-kappaB signaling pathway by IKKbeta in ventricular myocytes suppressed mitochondrial permeability transition pore (PTP) opening and cell death provoked by BNIP3. Expression of IKKbeta or p65 NF-kappaB suppressed basal and hypoxia-inducible BNIP3 gene activity. Deletion analysis of the BNIP3 promoter revealed the NF-kappaB elements to be crucial for inhibiting basal and inducible BNIP3 gene activity. Cells derived from p65(-/-)-deficient mice or ventricular myocytes rendered defective for NF-kappaB signaling with a nonphosphorylative IkappaB exhibited increased basal BNIP3 gene expression, mitochondrial PTP, and cell death. Genetic or functional ablation of the BNIP3 gene in NF-kappaB-defective myocytes rescued them from mitochondrial defects and cell death. CONCLUSIONS The data provide new compelling evidence that NF-kappaB suppresses mitochondrial defects and cell death of ventricular myocytes through a mechanism that transcriptionally silences the death gene BNIP3. Collectively, our data provide new mechanistic insight into the mode by which NF-kappaB suppresses cell death and identify BNIP3 as a key transcriptional target for NF-kappaB-regulated expression in ventricular myocytes.
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Affiliation(s)
- Delphine Baetz
- Department of Physiology, Institute of Cardiovascular Sciences, St Boniface General Hospital Research Centre, Winnipeg, Manitoba, Canada
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27
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Williams SD, Zhu H, Zhang L, Bernstein HS. Adenoviral delivery of human CDC5 promotes G2/M progression and cell division in neonatal ventricular cardiomyocytes. Gene Ther 2006; 13:837-43. [PMID: 16482203 DOI: 10.1038/sj.gt.3302737] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Heart failure results from the cumulative death of cardiomyocytes, and the inability of remaining cells to regenerate. Efforts toward transcriptional reprogramming of cardiomyocytes by overexpressing E1A or E2F1 have been limited by the inability of cardiomyocytes to enter and complete mitosis. Human CDC5 (hCDC5), a component of the pre-mRNA splicing complex, has been shown to regulate G2/M transit in asynchronously dividing cells. We now show that co-infection of recombinant adenoviruses expressing E1A/E1B and hCDC5 promotes cell cycle re-entry and G2/M progression in post-mitotic cardiomyocytes. Co-expression of E1A/E1B and hCDC5 induced nuclear localization of cyclin-dependent kinase 1 and cyclin B1, and was sufficient to promote mitotic entry as determined by an increase in mitotic index only in co-infected cells. E1A/E1B and hCDC5 promoted cell division, as evidenced by an increase in the number of cardiomyocytes following co-infection. Thus, overexpression of E1A/E1B and hCDC5 resulted in cell cycle re-entry, DNA synthesis, cell division, and an increase in cardiomyocyte number, suggesting the formation of new cardiomyocytes. These studies suggest that G1/S-phase transcriptional regulators, in combination with pre-mRNA splicing factors, such as CDC5, that regulate rate-limiting G2/M target genes may prove useful in developing therapies to stimulate myocardial regeneration.
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Affiliation(s)
- S D Williams
- Cardiovascular Research Institute, University of California, San Francisco, CA 92121, USA
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28
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Ito H. [Cell cycle and heart failure]. Nihon Yakurigaku Zasshi 2005; 126:381-4. [PMID: 16462088 DOI: 10.1254/fpj.126.381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
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29
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Nicassio F, Bianchi F, Capra M, Vecchi M, Confalonieri S, Bianchi M, Pajalunga D, Crescenzi M, Bonapace IM, Di Fiore PP. A cancer-specific transcriptional signature in human neoplasia. J Clin Invest 2005; 115:3015-25. [PMID: 16224537 PMCID: PMC1253624 DOI: 10.1172/jci24862] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2005] [Accepted: 07/26/2005] [Indexed: 02/06/2023] Open
Abstract
The molecular anatomy of cancer cells is being explored through unbiased approaches aimed at the identification of cancer-specific transcriptional signatures. An alternative biased approach is exploitation of molecular tools capable of inducing cellular transformation. Transcriptional signatures thus identified can be readily validated in real cancers and more easily reverse-engineered into signaling pathways, given preexisting molecular knowledge. We exploited the ability of the adenovirus early region 1 A protein (E1A) oncogene to force the reentry into the cell cycle of terminally differentiated cells in order to identify and characterize genes whose expression is upregulated in this process. A subset of these genes was activated through a retinoblastoma protein/E2 viral promoter required factor-independent (pRb/E2F-independent) mechanism and was overexpressed in a fraction of human cancers. Furthermore, this overexpression correlated with tumor progression in colon cancer, and 2 of these genes predicted unfavorable prognosis in breast cancer. A proof of principle biological validation was performed on one of the genes of the signature, skeletal muscle cell reentry-induced (SKIN) gene, a previously undescribed gene. SKIN was found overexpressed in some primary tumors and tumor cell lines and was amplified in a fraction of colon adenocarcinomas. Furthermore, knockdown of SKIN caused selective growth suppression in overexpressing tumor cell lines but not in tumor lines expressing physiological levels of the transcript. Thus, SKIN is a candidate oncogene in human cancer.
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Affiliation(s)
- Francesco Nicassio
- IFOM, Istituto Fondazione Italiana per la Ricerca sul Cancro di Oncologia Molecolare, Milan, Italy
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Ha KC, Chae HJ, Piao CS, Kim SH, Kim HR, Chae SW. Dendroaspis natriuretic peptide induces the apoptosis of cardiac muscle cells. Immunopharmacol Immunotoxicol 2005; 27:33-51. [PMID: 15803858 DOI: 10.1081/iph-51292] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Early heart failure is characterized by elevated plasma Dendroaspis natriuretic peptide-like immunoreactivity (DNP-LI). However, the direct effects of DNP on heart or the heart-associated cell system are not well known. Therefore, we investigated whether DNP induces the apoptosis of H9c2 cardiac muscle cells. H9c2 cardiac muscle cells and rat neonatal cardiomyocytes were treated with various concentrations of DNP. Cell viability and nuclear morphology change were determined by trypan blue staining and Hoechst 33258 staining, respectively. Caspase-3-like activity was measured using specific fluorogenic substrates. Pro-and antiapoptotic proteins were assayed by Western blotting. DNP induced the apoptosis of H9c2 cardiac muscle cells in a dose-dependent manner. Maximum effects occurred at 100 nM concentration of DNP, with a 7-8-fold increase in apoptotic cells, to reach a maximum apoptotic index of 17%. We also identified that H9c2 cardiac muscle cells expressed Natriuretic peptide reactor -A and -B, which respond to DNP to generate cGMP. The treatment with DNP also markedly reduced levels of Bcl-2, inhibitor of apoptosis protein-1, and inhibitor of apoptosis protein-2 and increased the level of Bax and cytochrome c release into cytoplasm and subsequent caspase-3 activation, which co-occurred with increased apoptosis. DNP-induced apoptosis was mediated by cyclic GMP, and this effect was mimicked by dibutylyl-cGMP (30 microM), a membrane permeable analog of cGMP. Furthermore, DNP-induced apoptosis was observed in rat neonatal cardiomyocytes. These results suggest that DNP induces the apoptosis of H9c2 cardiac muscle cells and of cardiomyocytes via cGMP and demonstrate that the operative mechanism includes the regulation of Bcl-2 family proteins.
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Affiliation(s)
- Ki-Chan Ha
- Department of Pharmacology, Institute of Cardiovascular Research, Chonbuk National University Medical School, Chonju, Chonbuk, South Korea
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31
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McMullen NM, Gaspard GJ, Pasumarthi KBS. Reactivation of cardiomyocyte cell cycle: A potential approach for myocardial regeneration. ACTA ACUST UNITED AC 2005. [DOI: 10.1002/sita.200400050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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32
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Poizat C, Puri PL, Bai Y, Kedes L. Phosphorylation-dependent degradation of p300 by doxorubicin-activated p38 mitogen-activated protein kinase in cardiac cells. Mol Cell Biol 2005; 25:2673-87. [PMID: 15767673 PMCID: PMC1061628 DOI: 10.1128/mcb.25.7.2673-2687.2005] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
p300 and CBP are general transcriptional coactivators implicated in different cellular processes, including regulation of the cell cycle, differentiation, tumorigenesis, and apoptosis. Posttranslational modifications such as phosphorylation are predicted to select a specific function of p300/CBP in these processes; however, the identification of the kinases that regulate p300/CBP activity in response to individual stimuli and the physiological significance of p300 phosphorylation have not been elucidated. Here we demonstrate that the cardiotoxic anticancer agent doxorubicin (adriamycin) induces the phosphorylation of p300 in primary neonatal cardiomyocytes. Hyperphosphorylation precedes the degradation of p300 and parallels apoptosis in response to doxorubicin. Doxorubicin-activated p38 kinases alpha and beta associate with p300 and are implicated in the phosphorylation-mediated degradation of p300, as pharmacological blockade of p38 prevents p300 degradation. p38 phosphorylates p300 in vitro at both the N and C termini of the protein, and enforced activation of p38 by the constitutively active form of its upstream kinase (MKK6EE) triggers p300 degradation. These data support the conclusion that p38 mitogen-activated protein kinase regulates p300 protein stability and function in cardiomyocytes undergoing apoptosis in response to doxorubicin.
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Affiliation(s)
- Coralie Poizat
- Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, 2250 Alcazar St., CSC 245, Los Angeles, CA 90033, USA.
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33
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MacLellan WR, Garcia A, Oh H, Frenkel P, Jordan MC, Roos KP, Schneider MD. Overlapping roles of pocket proteins in the myocardium are unmasked by germ line deletion of p130 plus heart-specific deletion of Rb. Mol Cell Biol 2005; 25:2486-97. [PMID: 15743840 PMCID: PMC1061608 DOI: 10.1128/mcb.25.6.2486-2497.2005] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Revised: 12/10/2004] [Accepted: 12/15/2004] [Indexed: 11/20/2022] Open
Abstract
The pocket protein family of tumor suppressors, and Rb specifically, have been implicated as controlling terminal differentiation in many tissues, including the heart. To establish the biological functions of Rb in the heart and overcome the early lethality caused by germ line deletion of Rb, we used a Cre/loxP system to create conditional, heart-specific Rb-deficient mice. Mice that are deficient in Rb exclusively in cardiac myocytes (CRbL/L) are born with the expected Mendelian distribution, and the adult mice displayed no change in heart size, myocyte cell cycle distribution, myocyte apoptosis, or mechanical function. Since both Rb and p130 are expressed in the adult myocardium, we created double-knockout mice (CRbL/L p130-/-) to determine it these proteins have a shared role in regulating cardiac myocyte cell cycle progression. Adult CRbL/L p130-/- mice demonstrated a threefold increase in the heart weight-to-body weight ratio and showed increased numbers of bromodeoxyuridine- and phosphorylated histone H3-positive nuclei, consistent with persistent myocyte cycling. Likewise, the combined deletion of Rb plus p130 up-regulated myocardial expression of Myc, E2F-1, and G1 cyclin-dependent kinase activities, synergistically. Thus, Rb and p130 have overlapping functional roles in vivo to suppress cell cycle activators, including Myc, and maintain quiescence in postnatal cardiac muscle.
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Affiliation(s)
- W R MacLellan
- Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 675 C. E. Young Dr., MRL 3-645, Los Angeles, CA 90095-1760, USA.
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Regula KM, Baetz D, Kirshenbaum LA. Nuclear Factor-κB Represses Hypoxia-Induced Mitochondrial Defects and Cell Death of Ventricular Myocytes. Circulation 2004; 110:3795-802. [PMID: 15596562 DOI: 10.1161/01.cir.0000150537.59754.55] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Background—
Oxygen deprivation for prolonged periods of time provokes cardiac cell death and ventricular dysfunction. Preventing inappropriate cardiac cell death in patients with ischemic heart disease would be of significant therapeutic value as a means to improve ventricular performance. In the present study, we wished to ascertain whether activation of the cellular factor nuclear factor (NF)-κB suppresses mitochondrial defects and cell death of ventricular myocytes during hypoxic injury.
Methods and Results—
In contrast to normoxic control cells, ventricular myocytes subjected to hypoxia displayed a 9.1-fold increase (
P
<0.05) in cell death, as determined by Hoechst 33258 nuclear staining and vital dyes. Mitochondrial defects consistent with permeability transition pore opening, loss of mitochondrial membrane potential (ΔΨm), and Smac release were observed in cells subjected to hypoxia. An increase in postmitochondrial caspase 9 and caspase 3 activity was observed in hypoxic myocytes. Adenovirus-mediated delivery of wild-type IKKβ (IKKβwt) resulted in a significant increase in NF-κB-dependent DNA binding and gene transcription in ventricular myocytes. Interestingly, subcellular fractionation of myocytes revealed that the p65 subunit of NF-κB was localized to mitochondria. Hypoxia-induced mitochondrial defects and cell death were suppressed in cells expressing IKKβwt but not in cells expressing the kinase-defective IKKβ mutant.
Conclusions—
To the best of our knowledge, the data provide the first direct evidence that activation of the NF-κB signaling pathways is sufficient to suppress cell death of ventricular myocytes during hypoxia. Moreover, our data further suggest that NF-κB averts cell death through a mechanism that prevents perturbations to the mitochondrion during hypoxic injury.
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Affiliation(s)
- Kelly M Regula
- Institute of Cardiovascular Sciences, St Boniface General Hospital Research Centre, Department of Physiology, Faculty of Medicine University of Manitoba, Winnipeg, Manitoba, Canada
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35
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Dilley RJ. A novel inhibitory role for CREG-mediated signalling in cardiac hypertrophy? J Hypertens 2004; 22:1469-71. [PMID: 15257166 DOI: 10.1097/01.hjh.0000133741.00738.a2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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36
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Dätwyler DA, Magyar JP, Weikert C, Wightman L, Wagner E, Eppenberger HM. Reactivation of the mitosis-promoting factor in postmitotic cardiomyocytes. Cells Tissues Organs 2004; 175:61-71. [PMID: 14605485 DOI: 10.1159/000073750] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2003] [Indexed: 11/19/2022] Open
Abstract
Cardiomyocytes cease to divide shortly after birth and an irreversible cell cycle arrest is evident accompanied by the downregulation of cyclin-dependent kinase activities. To get a better understanding of the cardiac cell cycle and its regulation, the effect of functional recovery of the mitosis-promoting factor (MPF) consisting of cyclin B1 and the cyclin-dependent kinase Cdc2 was assessed in primary cultures of postmitotic ventricular adult rat cardiomyocytes (ARC). Gene transfer into ARC was achieved using the adenovirus-enhanced transferrinfection system that was characterized by the absence of cytotoxic events. Simultaneous ectopic expression of wild-type versions of cyclin B1 and Cdc2 was sufficient to induce MPF activity. Reestablished MPF resulted in a mitotic phenotype, marked by an abnormal condensation of the nuclei, histone H3 phosphorylation and variable degree of decay of the contractile apparatus. Although a complete cell division was not observed, the results provided conclusive evidence that cell cycle-related events in postmitotic cardiomyocytes could be triggered by genetic intervention downstream of the G1/S checkpoint. This will be of importance to design novel strategies to overcome the proliferation arrest in adult cardiomyocytes.
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Affiliation(s)
- Daniel A Dätwyler
- Institute of Cell Biology, Swiss Federal Institute of Technology, Zürich, Switzerland
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37
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38
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Hirai M, Ono K, Morimoto T, Kawamura T, Wada H, Kita T, Hasegawa K. FOG-2 competes with GATA-4 for transcriptional coactivator p300 and represses hypertrophic responses in cardiac myocytes. J Biol Chem 2004; 279:37640-50. [PMID: 15220332 DOI: 10.1074/jbc.m401737200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A multizinc finger protein, FOG-2, associates with a cardiac transcription factor, GATA-4, and represses GATA-4-dependent transcription. GATA-4 is required not only for normal heart development but is also involved in hypertrophic responses in cardiac myocytes; however, the effects of FOG-2 on these responses are unknown. The interaction of GATA-4 with a transcriptional coactivator p300 is required for its full transcriptional activity and the activation of the embryonic program during myocardial cell hypertrophy. We show here that exogenous FOG-2 represses phenylephrine-induced hypertrophic responses such as myofibrillar organization, increases in cell size, and hypertrophy-associated gene transcription. Using immunoprecipitation Western blotting, we demonstrate that FOG-2 physically interacted with p300 and reduced the binding of GATA-4 to p300. In addition, in COS7 cells, in which the function of endogenous p300 is disrupted, FOG-2 is unable to repress the GATA-4-dependent transcriptional activities; however, FOG-2 markedly repressed the p300-mediated increase in the DNA-binding and transcriptional activities of GATA-4 in these cells. Similarly, FOG-2 inhibited a phenylephrine-induced increase in the p300/GATA-4 interaction, the GATA-4/DNA-binding, and transcriptional activities of GATA-4-dependent promoters in cardiac myocytes as well. These findings demonstrate that FOG-2 represses hypertrophic responses in cardiac myocytes and that p300 is involved in these repressive effects.
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Affiliation(s)
- Maretoshi Hirai
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
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39
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Nakajima H, Nakajima HO, Tsai SC, Field LJ. Expression of Mutant p193 and p53 Permits Cardiomyocyte Cell Cycle Reentry After Myocardial Infarction in Transgenic Mice. Circ Res 2004; 94:1606-14. [PMID: 15142950 DOI: 10.1161/01.res.0000132279.99249.f4] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Previous studies have demonstrated that expression of p193 and p53 mutants with dominant-interfering activities renders embryonic stem cell-derived cardiomyocytes responsive to the growth promoting activities of the E1A viral oncoproteins. In this study, the effects of p53 and p193 antagonization on cardiomyocyte cell cycle activity in normal and infarcted hearts were examined. Transgenic mice expressing the p193 and/or the p53 dominant-interfering mutants in the heart were generated. Transgene expression had no effect on cardiomyocyte cell cycle activity in uninjured adult hearts. In contrast expression of either transgene resulted in a marked induction of cardiomyocyte cell cycle activity at the infarct border zone at 4 weeks after permanent coronary artery occlusion. Expression of the p193 dominant-interfering mutant was also associated with an induction of cardiomyocyte DNA synthesis in the interventricular septa of infarcted hearts. A concomitant and marked reduction in hypertrophic cardiomyocyte growth was observed in the septa of hearts expressing the p193 dominant-interfering transgene, suggesting that cell cycle activation might partially counteract the adverse ventricular remodeling that occurs after infarction. Collectively these data suggest that antagonization of p193 and p53 activity relaxes the otherwise stringent regulation of cardiomyocyte cell cycle reentry in the injured adult heart.
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Affiliation(s)
- Hidehiro Nakajima
- Wells Center for Pediatric Research and Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis, Ind 46202-5225, USA
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40
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Chaudhry HW, Dashoush NH, Tang H, Zhang L, Wang X, Wu EX, Wolgemuth DJ. Cyclin A2 mediates cardiomyocyte mitosis in the postmitotic myocardium. J Biol Chem 2004; 279:35858-66. [PMID: 15159393 DOI: 10.1074/jbc.m404975200] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cell cycle withdrawal limits proliferation of adult mammalian cardiomyocytes. Therefore, the concept of stimulating myocyte mitotic divisions has dramatic implications for cardiomyocyte regeneration and hence, cardiovascular disease. Previous reports describing manipulation of cell cycle proteins have not shown induction of cardiomyocyte mitosis after birth. We now report that cyclin A2, normally silenced in the postnatal heart, induces cardiac enlargement because of cardiomyocyte hyperplasia when constitutively expressed from embryonic day 8 into adulthood. Cardiomyocyte hyperplasia during adulthood was coupled with an increase in cardiomyocyte mitosis, noted in transgenic hearts at all time points examined, particularly during postnatal development. Several stages of mitosis were observed within cardiomyocytes and correlated with the nuclear localization of cyclin A2. Magnetic resonance analysis confirmed cardiac enlargement. These results reveal a previously unrecognized critical role for cyclin A2 in mediating cardiomyocyte mitosis, a role that may significantly impact upon clinical treatment of damaged myocardium.
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Affiliation(s)
- Hina W Chaudhry
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
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41
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Kawamura T, Ono K, Morimoto T, Akao M, Iwai-Kanai E, Wada H, Sowa N, Kita T, Hasegawa K. Endothelin-1-dependent nuclear factor of activated T lymphocyte signaling associates with transcriptional coactivator p300 in the activation of the B cell leukemia-2 promoter in cardiac myocytes. Circ Res 2004; 94:1492-9. [PMID: 15117818 DOI: 10.1161/01.res.0000129701.14494.52] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Endothelin-1 (ET-1) is a potent survival factor that protects cardiac myocytes from apoptosis. ET-1 induces cardiac gene transcription and protein expression of antiapoptotic B cell leukemia-2 (bcl-2) in a calcineurin-dependent manner. A cellular target of adenovirus early region 1A (E1A) oncoprotein, p300 also activates bcl-2 transcription in cardiac myocytes and is required for their survival. p300 acts as a calcineurin-regulated nuclear factors of activated T lymphocytes (NFATc), downstream targets of calcineurin. In addition, the bcl-2 promoter contains multiple NFAT consensus sequences. These findings prompted us to investigate the role of NFATc in ET-1-dependent and p300-dependent bcl-2 transcription in cardiac myocytes. In primary cardiac myocytes prepared from neonatal rats, mutation of 2 NFAT sites within the bcl-2 promoter completely abolished the ET-1- and p300-induced increases in the activity of this promoter. We show here that p300 markedly potentiates the binding of NFATc1 to the bcl-2 NFAT element by interacting with NFATc1 in an E1A-dependent manner. On the other hand, stimulation of cardiac myocytes with ET-1 causes nuclear translocation of NFATc1, which interacts with p300 and increases DNA binding. Expression of E1A did not change the cardiac nuclear localization of NFATc1 but blocked its interaction with p300, DNA binding, and bcl-2 promoter activation. These findings suggest that ET-1-dependent NFATc signaling associates with p300 in the transactivation of bcl-2 gene in cardiac myocytes.
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Affiliation(s)
- Teruhisa Kawamura
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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42
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Kawamura T, Hasegawa K, Morimoto T, Iwai-Kanai E, Miyamoto S, Kawase Y, Ono K, Wada H, Akao M, Kita T. Expression of p300 protects cardiac myocytes from apoptosis in vivo. Biochem Biophys Res Commun 2004; 315:733-8. [PMID: 14975762 DOI: 10.1016/j.bbrc.2004.01.105] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2003] [Indexed: 10/26/2022]
Abstract
Doxorubicin is an anti-tumor agent that represses cardiac-specific gene expression and induces myocardial cell apoptosis. Doxorubicin depletes cardiac p300, a transcriptional coactivator that is required for the maintenance of the differentiated phenotype of cardiac myocytes. However, the role of p300 in protection against doxorubicin-induced apoptosis is unknown. Transgenic mice overexpressing p300 in the heart and wild-type mice were subjected to doxorubicin treatment. Compared with wild-type mice, transgenic mice exhibited higher survival rate as well as more preserved left ventricular function and cardiac expression of alpha-sarcomeric actin. Doxorubicin induced myocardial cell apoptosis in wild-type mice but not in transgenic mice. Expression of p300 increased the cardiac level of bcl-2 and mdm-2, but not that of p53 or other members of the bcl-2 family. These findings demonstrate that overexpression of p300 protects cardiac myocytes from doxorubicin-induced apoptosis and reduces the extent of acute heart failure in adult mice in vivo.
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Affiliation(s)
- Teruhisa Kawamura
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, 54 Kawara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
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43
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Ji A, Dao D, Chen J, MacLellan WR. EID-2, a novel member of the EID family of p300-binding proteins inhibits transactivation by MyoD. Gene 2004; 318:35-43. [PMID: 14585496 DOI: 10.1016/j.gene.2003.06.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Skeletal muscle differentiation has been shown to be dependent on the expression of Rb and p300. We recently cloned a novel inhibitor of muscle differentiation called EID-1, which interacted with both of these factors. In a database search for related molecules, we have cloned and characterized a new EID-1 family member, EID-2. This 28-kDa protein encodes a 236-amino-acid protein with significant similarity to EID-1 in its C-terminus. EID-2 displays developmentally regulated expression with high levels in adult heart and brain. Overexpression of EID-2 inhibits muscle-specific gene expression through inhibition of MyoD-dependent transcription. This inhibitory effect on gene expression can be explained by EID-2's ability to associate with and inhibit the acetyltransferase activity of p300. These data suggest that EID-1 and -2 represent a novel family of proteins that negatively regulate differentiation through a p300-dependent mechanism.
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MESH Headings
- Acetyltransferases/metabolism
- Actins/genetics
- Actins/metabolism
- Adult
- Amino Acid Sequence
- Animals
- Base Sequence
- Carrier Proteins/chemistry
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Cell Line
- Cell Line, Tumor
- Cells, Cultured
- Cloning, Molecular
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Female
- Gene Expression
- Histone Acetyltransferases
- Humans
- Inhibitor of Differentiation Protein 2
- Intracellular Signaling Peptides and Proteins
- Molecular Sequence Data
- Molecular Weight
- Muscle, Skeletal/cytology
- Muscle, Skeletal/metabolism
- MyoD Protein/genetics
- MyoD Protein/metabolism
- Myosin Heavy Chains/genetics
- Myosin Heavy Chains/metabolism
- Nuclear Proteins/genetics
- Nuclear Proteins/metabolism
- Protein Binding
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Transcription, Genetic
- Transcriptional Activation
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Affiliation(s)
- Aimin Ji
- Cardiovascular Research Laboratories, Department of Medicine, David Geffen School of Medicine at UCLA, MRL 3-645, 675 C.E. Young Dr, Los Angeles, CA 90095-1760, USA
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44
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Abstract
Lower vertebrates such as newt and zebrafish are able to reactivate high levels of cardiomyocyte cell cycle activity in response to experimental injury resulting in apparent regeneration. In contrast, damaged myocardium is replaced by fibrotic scar tissue in higher vertebrates. This process compromises the contractile function of the surviving myocardium, ultimately leading to heart failure. Various strategies are being pursued to augment myocyte number in the diseased hearts. One approach entails the reactivation of cell cycle in surviving cardiomyocytes. Here, we provide a summary of methods to monitor cell cycle activity, and interventions demonstrating positive cell cycle effects in cardiomyocytes as well as discuss the potential utility of cell cycle regulation to augment myocyte number in diseased hearts.
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Affiliation(s)
- Joshua D Dowell
- Wells Center for Pediatric Research and Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis, IN 46202-5225, USA
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45
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Yanazume T, Morimoto T, Wada H, Kawamura T, Hasegawa K. Biological role of p300 in cardiac myocytes. Mol Cell Biochem 2003; 248:115-9. [PMID: 12870662 DOI: 10.1023/a:1024132217870] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A cellular target of adenovirus E1A oncoprotein, p300 is a transcriptional coactivator required for the maintenance of differentiated phenotypes in cardiac myocytes. The full transcriptional activities of hypertrophy-responsive transcription factors such as GATA-4 and MEF2 require interaction with p300. A p300 protein also possesses intrinsic histone acetyl transferase activity, which promotes a transcriptionally active chromatin configuration. Here, we review the biological functions of p300 in cardiac myocytes. Although p300 is biologically active in many cell types, this protein appears to play a crucial role in the differentiation, growth and apoptosis of cardiac myocytes. Understanding precise mechanisms of its biological functions will shed light on molecular pathways for heart failure.
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Affiliation(s)
- Tetsuhiko Yanazume
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Shogoin, Sakyo-ku, Kyoto, Japan
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46
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Tamamori-Adachi M, Ito H, Sumrejkanchanakij P, Adachi S, Hiroe M, Shimizu M, Kawauchi J, Sunamori M, Marumo F, Kitajima S, Ikeda MA. Critical role of cyclin D1 nuclear import in cardiomyocyte proliferation. Circ Res 2003; 92:e12-9. [PMID: 12522130 DOI: 10.1161/01.res.0000049105.15329.1c] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Mammalian cardiomyocytes irreversibly lose their capacity to proliferate soon after birth, yet the underlying mechanisms have been unclear. Cyclin D1 and its partner, cyclin-dependent kinase 4 (CDK4), are important for promoting the G1-to-S phase progression via phosphorylation of the retinoblastoma (Rb) protein. Mitogenic stimulation induces hypertrophic cell growth and upregulates expression of cyclin D1 in postmitotic cardiomyocytes. In the present study, we show that, in neonatal rat cardiomyocytes, D-type cyclins and CDK4 were predominantly cytoplasmic, whereas Rb remained in an underphosphorylated state. Ectopically expressed cyclin D1 localized in the nucleus of fetal but not neonatal cardiomyocytes. To target cyclin D1 to the nucleus efficiently, we constructed a variant of cyclin D1 (D1NLS), which directly linked to nuclear localization signals (NLSs). Coinfection of recombinant adenoviruses expressing D1NLS and CDK4 induced Rb phosphorylation and CDK2 kinase activity. Furthermore, D1NLS/CDK4 was sufficient to promote the reentry into the cell cycle, leading to cell division. The number of cardiomyocytes coinfected with these viruses increased 3-fold 5 days after infection. Finally, D1NLS/CDK4 promoted cell cycle reentry of cardiomyocytes in adult hearts injected with these viruses, evaluated by the expression of Ki-67, which is expressed in proliferating cells in all phases of the cell cycle, and BrdU incorporation. Thus, postmitotic cardiomyocytes have the potential to proliferate provided that cyclin D1/CDK4 accumulate in the nucleus, and the prevention of their nuclear import plays a critical role as a physical barrier to prevent cardiomyocyte proliferation. Our results provide new insights into the development of therapeutics strategies to induce regeneration of cardiomyocytes. The full text of this article is available at http://www.circresaha.org.
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Affiliation(s)
- Mimi Tamamori-Adachi
- Department of Biochemical Genetics, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
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47
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Engel FB, Hauck L, Boehm M, Nabel EG, Dietz R, von Harsdorf R. p21(CIP1) Controls proliferating cell nuclear antigen level in adult cardiomyocytes. Mol Cell Biol 2003; 23:555-65. [PMID: 12509454 PMCID: PMC151523 DOI: 10.1128/mcb.23.2.555-565.2003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Cell cycle withdrawal associated with terminal differentiation is responsible for the incapability of many organs to regenerate after injury. Here, we employed a cell-free system to analyze the molecular mechanisms underlying cell cycle arrest in cardiomyocytes. In this assay, incubation of S phase nuclei mixed with cytoplasmic extract of S phase cells and adult primary cardiomyocytes results in a dramatic reduction of proliferating cell nuclear antigen (PCNA) protein levels. This effect was blocked by the proteasome inhibitors MG132 and lactacystin, whereas actinomycin D and cycloheximide had no effect. Immunodepletion and addback experiments revealed that the effect of cardiomyocyte extract on PCNA protein levels is maintained by p21 but not p27. In serum-stimulated cardiomyocytes PCNA expression was reconstituted, whereas the protein level of p21 but not that of p27 was reduced. Cytoplasmic extract of serum-stimulated cardiomyocytes did not influence the PCNA protein level in S phase nuclei. Moreover, the hypertrophic effect of serum stimulation was blocked by ectopic expression of p21 and the PCNA protein level was found to be upregulated in adult cardiomyocytes derived from p21 knockout mice. Our data provide evidence that p21 regulates the PCNA protein level in adult cardiomyocytes, which has implications for cardiomyocyte growth control.
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Affiliation(s)
- Felix B Engel
- Department of Cardiology, Campus Virchow Clinic, Charité, Humboldt University, Max Delbrück Center for Molecular Medicine, Berlin, Germany
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Regula KM, Ens K, Kirshenbaum LA. IKK beta is required for Bcl-2-mediated NF-kappa B activation in ventricular myocytes. J Biol Chem 2002; 277:38676-82. [PMID: 12167626 DOI: 10.1074/jbc.m206175200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The transcription factor nuclear factor kappa B (NF-kappa B) is regulated by cytoplasmic inhibitor I kappa B alpha. An integral step in the activation of NF-kappa B involves the phosphorylation and degradation of I kappa B alpha. We have previously reported that I kappa B alpha activity is diminished in ventricular myocytes expressing Bcl-2 (de Moissac, D., Zheng, H., and Kirshenbaum, L. A. (1999) J. Biol. Chem. 274, 29505-29509). The underlying mechanism by which Bcl-2 activates NF-kappa B is undefined. In view of growing evidence that the I kappa B kinases (IKKs), notably IKK beta, are involved in signal induced phosphorylation of I kappa B alpha, we ascertained whether IKK beta is necessary and sufficient for Bcl-2 mediated NF-kappa B activation. Here we demonstrate that expression of Bcl-2 in ventricular myocytes resulted in an increase in NF-kappa B-dependent DNA binding, NF-kappa B gene transcription and reduced I kappa B alpha levels. An increase in the IKK beta kinase activity was observed in cells expressing full-length Bcl-2 but not in cells expressing the BH4 deletion mutant of Bcl-2 (Delta BH4; residues 10-30). Catalytically inactive mutants of IKK beta, but not IKK alpha, suppressed Bcl-2-mediated I kappa B alpha phosphorylation and NF-kappa B activation. Transfection of human embryonic 293 cells with a kinase-defective Raf-1 or a kinase-defective mitogen-activated protein kinase/extracellular signal-regulated kinase kinase-1 (MEKK-1) suppressed Bcl-2-mediated IKK beta activity and NF-kappa B activation. Further, Bcl-2-mediated NF-kappa B activity was impaired in nullizygous mouse embryonic fibroblasts deficient for IKK beta. In this report, we provide the first direct evidence that Bcl-2 activates NF-kappa B by a signaling mechanism that involves Raf-1/MEKK-1 mediated activation of IKK beta.
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Affiliation(s)
- Kelly M Regula
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, and the Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba R2H 2A6, Canada
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Regula KM, Ens K, Kirshenbaum LA. Inducible expression of BNIP3 provokes mitochondrial defects and hypoxia-mediated cell death of ventricular myocytes. Circ Res 2002; 91:226-31. [PMID: 12169648 DOI: 10.1161/01.res.0000029232.42227.16] [Citation(s) in RCA: 261] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In this study, we provide evidence for the operation of BNIP3 as a key regulator of mitochondrial function and cell death of ventricular myocytes during hypoxia. In contrast to normoxic cells, a 5.6-fold increase (P<0.05) in myocyte death was observed in cells subjected to hypoxia. Moreover, a significant increase in BNIP3 expression was detected in postnatal ventricular myocytes and adult rat hearts subjected to hypoxia. An increase in BNIP3 expression was detected in adult rat hearts in vivo with chronic heart failure. Subcellular fractionation experiments indicated that endogenous BNIP3 was integrated into the mitochondrial membranes during hypoxia. Adenovirus-mediated delivery of full-length BNIP3 to myocytes was toxic and provoked an 8.3-fold increase (P<0.05) in myocyte death with features typical of apoptosis. Mitochondrial defects consistent with opening of the permeability transition pore (PT pore) were observed in cells expressing BNIP3 but not in cells expressing BNIP3 missing the carboxyl-terminal transmembrane domain (BNIP3DeltaTM), necessary for mitochondrial insertion. The pan-caspase inhibitor z-VAD-fmk (25 to 100 micromol/L) suppressed BNIP3-induced cell death of ventricular myocytes in a dose-dependent manner. Bongkrekic acid (50 micromol/L), an inhibitor of the PT pore, prevented BNIP3-induced mitochondrial defects and cell death. Expression of BNIP3DeltaTM suppressed the hypoxia-induced integration of the endogenous BNIP3 protein and cell death of ventricular myocytes. To our knowledge, the data provide the first evidence for the involvement of BNIP3 as an inducible factor that provokes mitochondrial defects and cell death of ventricular myocytes during hypoxia.
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Affiliation(s)
- Kelly M Regula
- Institute of Cardiovascular Sciences, St Boniface General Hospital Research Centre, and the Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
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Barnabé N, Zastre JA, Venkataram S, Hasinoff BB. Deferiprone protects against doxorubicin-induced myocyte cytotoxicity. Free Radic Biol Med 2002; 33:266-75. [PMID: 12106822 DOI: 10.1016/s0891-5849(02)00873-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The iron chelating hydroxypyridinone deferiprone (CP20, L1) and the clinically approved cardioprotective agent dexrazoxane (ICRF-187) were examined for their ability to protect neonatal rat cardiac myocytes from doxorubicin-induced damage. Doxorubicin is thought to induce oxidative stress on the heart muscle, both through reductive activation to its semiquinone form, and by the production of hydroxyl radicals mediated by its complex with iron. The results of this study showed that both deferiprone and dexrazoxane were able to protect myocytes from doxorubicin-induced lactate dehydrogenase release. Deferiprone quickly and efficiently removed iron(III) from its complex with doxorubicin. In addition, this study also showed that deferiprone rapidly entered myocytes and displaced iron from a fluorescence-quenched trapped intracellular iron-calcein complex, suggesting that in the myocyte, deferiprone should also be able to displace iron from its complex with doxorubicin. It was shown by electron paramagnetic resonance spectroscopy that under hypoxic conditions myocytes were able to reduce doxorubicin to its semiquinone free radical. Deferiprone also greatly reduced hydroxyl radical production by the iron(III)-doxorubicin complex in the xanthine oxidase/xanthine superoxide generating system. Together these results suggest that deferiprone may protect against doxorubicin-induced damage to myocytes by displacing iron bound to doxorubicin, or chelating free or loosely bound iron, thus preventing site-specific iron-based oxygen radical damage.
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Affiliation(s)
- Norman Barnabé
- Faculty of Pharmacy, University of Manitoba, Winnipeg, MB, Canada
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