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Aghagolzadeh P, Plaisance I, Bernasconi R, Treibel TA, Pulido Quetglas C, Wyss T, Wigger L, Nemir M, Sarre A, Chouvardas P, Johnson R, González A, Pedrazzini T. Assessment of the Cardiac Noncoding Transcriptome by Single-Cell RNA Sequencing Identifies FIXER, a Conserved Profibrogenic Long Noncoding RNA. Circulation 2023; 148:778-797. [PMID: 37427428 DOI: 10.1161/circulationaha.122.062601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 06/02/2023] [Indexed: 07/11/2023]
Abstract
BACKGROUND Cardiac fibroblasts have crucial roles in the heart. In particular, fibroblasts differentiate into myofibroblasts in the damaged myocardium, contributing to scar formation and interstitial fibrosis. Fibrosis is associated with heart dysfunction and failure. Myofibroblasts therefore represent attractive therapeutic targets. However, the lack of myofibroblast-specific markers has precluded the development of targeted therapies. In this context, most of the noncoding genome is transcribed into long noncoding RNAs (lncRNAs). A number of lncRNAs have pivotal functions in the cardiovascular system. lncRNAs are globally more cell-specific than protein-coding genes, supporting their importance as key determinants of cell identity. METHODS In this study, we evaluated the value of the lncRNA transcriptome in very deep single-cell RNA sequencing. We profiled the lncRNA transcriptome in cardiac nonmyocyte cells after infarction and probed heterogeneity in the fibroblast and myofibroblast populations. In addition, we searched for subpopulation-specific markers that can constitute novel targets in therapy for heart disease. RESULTS We demonstrated that cardiac cell identity can be defined by the sole expression of lncRNAs in single-cell experiments. In this analysis, we identified lncRNAs enriched in relevant myofibroblast subpopulations. Selecting 1 candidate we named FIXER (fibrogenic LOX-locus enhancer RNA), we showed that its silencing limits fibrosis and improves heart function after infarction. Mechanitically, FIXER interacts with CBX4, an E3 SUMO protein ligase and transcription factor, guiding CBX4 to the promoter of the transcription factor RUNX1 to control its expression and, consequently, the expression of a fibrogenic gene program.. FIXER is conserved in humans, supporting its translational value. CONCLUSIONS Our results demonstrated that lncRNA expression is sufficient to identify the various cell types composing the mammalian heart. Focusing on cardiac fibroblasts and their derivatives, we identified lncRNAs uniquely expressed in myofibroblasts. In particular, the lncRNA FIXER represents a novel therapeutic target for cardiac fibrosis.
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Affiliation(s)
- Parisa Aghagolzadeh
- Experimental Cardiology Unit, Division of Cardiology, Department of Cardiovascular Medicine, University of Lausanne Medical School, Switzerland (P.A., I.P., R.B., M.N., T.P.)
| | - Isabelle Plaisance
- Experimental Cardiology Unit, Division of Cardiology, Department of Cardiovascular Medicine, University of Lausanne Medical School, Switzerland (P.A., I.P., R.B., M.N., T.P.)
| | - Riccardo Bernasconi
- Experimental Cardiology Unit, Division of Cardiology, Department of Cardiovascular Medicine, University of Lausanne Medical School, Switzerland (P.A., I.P., R.B., M.N., T.P.)
| | - Thomas A Treibel
- Institute of Cardiovascular Sciences, University College London, United Kingdom (T.A.T.)
| | - Carlos Pulido Quetglas
- Department for BioMedical Research, University of Bern, Switzerland (C.P.Q., P.C., R.J.)
| | - Tania Wyss
- Department of Oncology, Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland (T.W.)
- Swiss Institute of Bioinformatics, Lausanne, Switzerland (T.W., L.W.)
| | - Leonore Wigger
- Swiss Institute of Bioinformatics, Lausanne, Switzerland (T.W., L.W.)
| | - Mohamed Nemir
- Experimental Cardiology Unit, Division of Cardiology, Department of Cardiovascular Medicine, University of Lausanne Medical School, Switzerland (P.A., I.P., R.B., M.N., T.P.)
| | - Alexandre Sarre
- Cardiovascular Assessment Facility, University of Lausanne, Switzerland (A.S.)
| | - Panagiotis Chouvardas
- Department for BioMedical Research, University of Bern, Switzerland (C.P.Q., P.C., R.J.)
| | - Rory Johnson
- Department for BioMedical Research, University of Bern, Switzerland (C.P.Q., P.C., R.J.)
| | - Arantxa González
- Program of Cardiovascular Diseases, CIMA Universidad de Navarra and IdiSNA, Pamplona, Spain (A.G.)
- CIBERCV, Madrid, Spain (A.G.)
| | - Thierry Pedrazzini
- Experimental Cardiology Unit, Division of Cardiology, Department of Cardiovascular Medicine, University of Lausanne Medical School, Switzerland (P.A., I.P., R.B., M.N., T.P.)
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2
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Plaisance I, Chouvardas P, Sun Y, Nemir M, Aghagolzadeh P, Aminfar F, Shen S, Shim WJ, Rochais F, Johnson R, Palpant N, Pedrazzini T. A transposable element into the human long noncoding RNA CARMEN is a switch for cardiac precursor cell specification. Cardiovasc Res 2023; 119:1361-1376. [PMID: 36537036 PMCID: PMC10262180 DOI: 10.1093/cvr/cvac191] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 10/20/2022] [Accepted: 11/04/2022] [Indexed: 03/25/2024] Open
Abstract
AIMS The major cardiac cell types composing the adult heart arise from common multipotent precursor cells. Cardiac lineage decisions are guided by extrinsic and cell-autonomous factors, including recently discovered long noncoding RNAs (lncRNAs). The human lncRNA CARMEN, which is known to dictate specification toward the cardiomyocyte (CM) and the smooth muscle cell (SMC) fates, generates a diversity of alternatively spliced isoforms. METHODS AND RESULTS The CARMEN locus can be manipulated to direct human primary cardiac precursor cells (CPCs) into specific cardiovascular fates. Investigating CARMEN isoform usage in differentiating CPCs represents therefore a unique opportunity to uncover isoform-specific functions in lncRNAs. Here, we identify one CARMEN isoform, CARMEN-201, to be crucial for SMC commitment. CARMEN-201 activity is encoded within an alternatively spliced exon containing a MIRc short interspersed nuclear element. This element binds the transcriptional repressor REST (RE1 Silencing Transcription Factor), targets it to cardiogenic loci, including ISL1, IRX1, IRX5, and SFRP1, and thereby blocks the CM gene program. In turn, genes regulating SMC differentiation are induced. CONCLUSIONS These data show how a critical physiological switch is wired by alternative splicing and functional transposable elements in a long noncoding RNA. They further demonstrated the crucial importance of the lncRNA isoform CARMEN-201 in SMC specification during heart development.
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Affiliation(s)
- Isabelle Plaisance
- Experimental Cardiology Unit, Division of Cardiology, University of Lausanne Medical School, Lausanne, Switzerland
| | | | - Yuliangzi Sun
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Mohamed Nemir
- Experimental Cardiology Unit, Division of Cardiology, University of Lausanne Medical School, Lausanne, Switzerland
| | - Parisa Aghagolzadeh
- Experimental Cardiology Unit, Division of Cardiology, University of Lausanne Medical School, Lausanne, Switzerland
| | - Farhang Aminfar
- Experimental Cardiology Unit, Division of Cardiology, University of Lausanne Medical School, Lausanne, Switzerland
| | - Sophie Shen
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Woo Jun Shim
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Francesca Rochais
- Aix Marseille University, Marseille Medical Genetics, INSERM, U1251, Marseille, France
| | - Rory Johnson
- Department of Medical Oncology, Inselspital, University of Bern, Bern, Switzerland
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
| | - Nathan Palpant
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Thierry Pedrazzini
- Experimental Cardiology Unit, Division of Cardiology, University of Lausanne Medical School, Lausanne, Switzerland
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Nemir M, Kay M, Maison D, Berthonneche C, Sarre A, Plaisance I, Pedrazzini T. Inhibition of the NOTCH1 Pathway in the Stressed Heart Limits Fibrosis and Promotes Recruitment of Non-Myocyte Cells into the Cardiomyocyte Fate. J Cardiovasc Dev Dis 2022; 9:jcdd9040111. [PMID: 35448087 PMCID: PMC9024539 DOI: 10.3390/jcdd9040111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 04/04/2022] [Accepted: 04/06/2022] [Indexed: 12/10/2022] Open
Abstract
Cardiac pathologies lead to an acute or gradual loss of cardiomyocytes. Because of the limited regenerative capacity of the mammalian heart, cardiomyocytes are only replaced by fibrotic tissue. Excessive fibrosis contributes to the deterioration of cardiac function and the transition to heart failure, which is the leading cause of morbidity and mortality worldwide. Currently, no treatments can promote replenishment of the injured heart with newly formed cardiomyocytes. In this context, regenerative strategies explore the possibility to promote recovery through induction of cardiomyocyte production from pre-existing cardiomyocytes. On the other hand, cardiac non-myocyte cells can be directly reprogrammed into induced cardiac precursor cells and cardiomyocytes, suggesting that these cells could be exploited to produce cardiomyocytes in vivo. Here, we provide evidence that the sequential activation and inhibition of the NOTCH1 signaling pathway in the stressed heart decreases fibrosis and improves cardiac function in the stressed heart. This is accompanied by the emergence of new cardiomyocytes from non-myocyte origin. Overall, our data show how a developmental pathway such as the NOTCH pathway can be manipulated to provide therapeutic benefit in the damaged heart.
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Affiliation(s)
- Mohamed Nemir
- Experimental Cardiology Unit, Division of Cardiology, Department of Cardiovascular Medicine, University of Lausanne Medical School, 1011 Lausanne, Switzerland; (M.N.); (M.K.); (D.M.); (I.P.)
| | - Maryam Kay
- Experimental Cardiology Unit, Division of Cardiology, Department of Cardiovascular Medicine, University of Lausanne Medical School, 1011 Lausanne, Switzerland; (M.N.); (M.K.); (D.M.); (I.P.)
| | - Damien Maison
- Experimental Cardiology Unit, Division of Cardiology, Department of Cardiovascular Medicine, University of Lausanne Medical School, 1011 Lausanne, Switzerland; (M.N.); (M.K.); (D.M.); (I.P.)
| | - Corinne Berthonneche
- Cardiovascular Assessment Facility, University of Lausanne, 1011 Lausanne, Switzerland; (C.B.); (A.S.)
| | - Alexandre Sarre
- Cardiovascular Assessment Facility, University of Lausanne, 1011 Lausanne, Switzerland; (C.B.); (A.S.)
| | - Isabelle Plaisance
- Experimental Cardiology Unit, Division of Cardiology, Department of Cardiovascular Medicine, University of Lausanne Medical School, 1011 Lausanne, Switzerland; (M.N.); (M.K.); (D.M.); (I.P.)
| | - Thierry Pedrazzini
- Experimental Cardiology Unit, Division of Cardiology, Department of Cardiovascular Medicine, University of Lausanne Medical School, 1011 Lausanne, Switzerland; (M.N.); (M.K.); (D.M.); (I.P.)
- Correspondence: ; Tel.: +41-21-314-0765
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4
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Plaisance I, Nemir M, Silakhor PA, Chouvardas P, de los Reyes S, Khalil H, Johnson R, Pedrazzini T. CARMEN-201, a specific isoform of an enhancer-associated long noncoding RNA controls smooth-muscle lineage specification in human cardiac precursor. Cytotherapy 2020. [DOI: 10.1016/j.jcyt.2020.03.095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Puttini S, Plaisance I, Barile L, Cervio E, Milano G, Marcato P, Pedrazzini T, Vassalli G. ALDH1A3 Is the Key Isoform That Contributes to Aldehyde Dehydrogenase Activity and Affects in Vitro Proliferation in Cardiac Atrial Appendage Progenitor Cells. Front Cardiovasc Med 2018; 5:90. [PMID: 30087899 PMCID: PMC6066537 DOI: 10.3389/fcvm.2018.00090] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 06/25/2018] [Indexed: 12/23/2022] Open
Abstract
High aldehyde dehydrogenase (ALDHhi) activity has been reported in normal and cancer stem cells. We and others have shown previously that human ALDHhi cardiac atrial appendage cells are enriched with stem/progenitor cells. The role of ALDH in these cells is poorly understood but it may come down to the specific ALDH isoform(s) expressed. This study aimed to compare ALDHhi and ALDHlo atrial cells and to identify the isoform(s) that contribute to ALDH activity, and their functional role. Methods and Results: Cells were isolated from atrial appendage specimens from patients with ischemic and/or valvular heart disease undergoing heart surgery. ALDHhi activity assessed with the Aldefluor reagent coincided with primitive surface marker expression (CD34+). Depending on their ALDH activity, RT-PCR analysis of ALDHhi and ALDHlo cells demonstrated a differential pattern of pluripotency genes (Oct 4, Nanog) and genes for more established cardiac lineages (Nkx2.5, Tbx5, Mef2c, GATA4). ALDHhi cells, but not ALDHlo cells, formed clones and were culture-expanded. When cultured under cardiac differentiation conditions, ALDHhi cells gave rise to a higher number of cardiomyocytes compared with ALDHlo cells. Among 19 ALDH isoforms known in human, ALDH1A3 was most highly expressed in ALDHhi atrial cells. Knocking down ALDH1A3, but not ALDH1A1, ALDH1A2, ALDH2, ALDH4A1, or ALDH8A1 using siRNA decreased ALDH activity and cell proliferation in ALDHhi cells. Conversely, overexpressing ALDH1A3 with a retroviral vector increased proliferation in ALDHlo cells. Conclusions: ALDH1A3 is the key isoform responsible for ALDH activity in ALDHhi atrial appendage cells, which have a propensity to differentiate into cardiomyocytes. ALDH1A3 affects in vitro proliferation of these cells.
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Affiliation(s)
- Stefania Puttini
- Cardiovascular Department, CHUV University Hospital, Lausanne, Switzerland
| | - Isabelle Plaisance
- Cardiovascular Department, CHUV University Hospital, Lausanne, Switzerland
| | - Lucio Barile
- Cardiocentro Ticino Foundation and Swiss Institute for Regenerative Medicine, Lugano, Switzerland
| | - Elisabetta Cervio
- Cardiocentro Ticino Foundation and Swiss Institute for Regenerative Medicine, Lugano, Switzerland
| | - Giuseppina Milano
- Cardiovascular Department, CHUV University Hospital, Lausanne, Switzerland.,Cardiocentro Ticino Foundation and Swiss Institute for Regenerative Medicine, Lugano, Switzerland
| | - Paola Marcato
- Departments of Pathology, Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada
| | - Thierry Pedrazzini
- Cardiovascular Department, CHUV University Hospital, Lausanne, Switzerland
| | - Giuseppe Vassalli
- Cardiovascular Department, CHUV University Hospital, Lausanne, Switzerland.,Cardiocentro Ticino Foundation and Swiss Institute for Regenerative Medicine, Lugano, Switzerland
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6
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Micheletti R, Plaisance I, Abraham BJ, Sarre A, Ting CC, Alexanian M, Maric D, Maison D, Nemir M, Young RA, Schroen B, González A, Ounzain S, Pedrazzini T. The long noncoding RNA Wisper controls cardiac fibrosis and remodeling. Sci Transl Med 2018. [PMID: 28637928 DOI: 10.1126/scitranslmed.aai9118] [Citation(s) in RCA: 207] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Long noncoding RNAs (lncRNAs) are emerging as powerful regulators of cardiac development and disease. However, our understanding of the importance of these molecules in cardiac fibrosis is limited. Using an integrated genomic screen, we identified Wisper (Wisp2 super-enhancer-associated RNA) as a cardiac fibroblast-enriched lncRNA that regulates cardiac fibrosis after injury. Wisper expression was correlated with cardiac fibrosis both in a murine model of myocardial infarction (MI) and in heart tissue from human patients suffering from aortic stenosis. Loss-of-function approaches in vitro using modified antisense oligonucleotides (ASOs) demonstrated that Wisper is a specific regulator of cardiac fibroblast proliferation, migration, and survival. Accordingly, ASO-mediated silencing of Wisper in vivo attenuated MI-induced fibrosis and cardiac dysfunction. Functionally, Wisper regulates cardiac fibroblast gene expression programs critical for cell identity, extracellular matrix deposition, proliferation, and survival. In addition, its association with TIA1-related protein allows it to control the expression of a profibrotic form of lysyl hydroxylase 2, implicated in collagen cross-linking and stabilization of the matrix. Together, our findings identify Wisper as a cardiac fibroblast-enriched super-enhancer-associated lncRNA that represents an attractive therapeutic target to reduce the pathological development of cardiac fibrosis in response to MI and prevent adverse remodeling in the damaged heart.
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Affiliation(s)
- Rudi Micheletti
- Experimental Cardiology Unit, Department of Cardiovascular Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Isabelle Plaisance
- Experimental Cardiology Unit, Department of Cardiovascular Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Brian J Abraham
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Alexandre Sarre
- Cardiovascular Assessment Facility, University of Lausanne, Lausanne, Switzerland
| | - Ching-Chia Ting
- Experimental Cardiology Unit, Department of Cardiovascular Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Michael Alexanian
- Experimental Cardiology Unit, Department of Cardiovascular Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Daniel Maric
- Experimental Cardiology Unit, Department of Cardiovascular Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Damien Maison
- Experimental Cardiology Unit, Department of Cardiovascular Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Mohamed Nemir
- Experimental Cardiology Unit, Department of Cardiovascular Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Richard A Young
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Blanche Schroen
- Center for Heart Failure Research, Department of Cardiology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, Netherlands
| | - Arantxa González
- Centre for Applied Medical Research, University of Navarra, Pamplona, Spain.,National Institute of Health Carlos III, Madrid, Spain
| | - Samir Ounzain
- Experimental Cardiology Unit, Department of Cardiovascular Medicine, University of Lausanne Medical School, Lausanne, Switzerland.
| | - Thierry Pedrazzini
- Experimental Cardiology Unit, Department of Cardiovascular Medicine, University of Lausanne Medical School, Lausanne, Switzerland.
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Plaisance I, Perruchoud S, Fernandez-Tenorio M, Gonzales C, Ounzain S, Ruchat P, Nemir M, Niggli E, Pedrazzini T. Cardiomyocyte Lineage Specification in Adult Human Cardiac Precursor Cells Via Modulation of Enhancer-Associated Long Noncoding RNA Expression. JACC Basic Transl Sci 2016; 1:472-493. [PMID: 29707678 PMCID: PMC5916868 DOI: 10.1016/j.jacbts.2016.06.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human CPCs produce predominantly smooth muscle cells. CPCs can be redirected to the cardiomyocyte fate by transient activation followed by inhibition of NOTCH signaling. Inhibition of NOTCH signaling during differentiation represses MIR-143/145 expression and blocks smooth muscle differentiation. Expression of the microRNAs is under control of CARMEN, a long noncoding RNA associated with an enhancer located in the MIR-143/145 locus and target of NOTCH signaling. The CARMEN/MIR-145/143 locus represents a promising therapeutic target to favor production of cardiomyocytes in cell replacement therapies.
The mechanisms controlling differentiation in adult cardiac precursor cells (CPCs) are still largely unknown. In this study, CPCs isolated from the human heart were found to produce predominantly smooth muscle cells but could be redirected to the cardiomyocyte fate by transient activation followed by inhibition of NOTCH signaling. NOTCH inhibition repressed MIR-143/145 expression, and blocked smooth muscle differentiation. Expression of the microRNAs is under control of CARMEN, a long noncoding RNA associated with an enhancer located in the MIR-143/145 locus and target of NOTCH signaling. The CARMEN/MIR-145/143 axis represents, therefore, a promising target to favor production of cardiomyocytes in cell replacement therapies.
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Affiliation(s)
- Isabelle Plaisance
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Stéphanie Perruchoud
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | | | - Christine Gonzales
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Samir Ounzain
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Patrick Ruchat
- Department of Cardiovascular Surgery, University of Lausanne Medical School, Lausanne, Switzerland
| | - Mohamed Nemir
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Ernst Niggli
- Department of Physiology, University of Bern, Bern, Switzerland
| | - Thierry Pedrazzini
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
- Reprint requests and correspondence: Dr. Thierry Pedrazzini, Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, CH-1011 Lausanne, Switzerland.
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8
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Ounzain S, Micheletti R, Arnan C, Plaisance I, Cecchi D, Schroen B, Reverter F, Alexanian M, Gonzales C, Ng SY, Bussotti G, Pezzuto I, Notredame C, Heymans S, Guigó R, Johnson R, Pedrazzini T. CARMEN, a human super enhancer-associated long noncoding RNA controlling cardiac specification, differentiation and homeostasis. J Mol Cell Cardiol 2015; 89:98-112. [PMID: 26423156 DOI: 10.1016/j.yjmcc.2015.09.016] [Citation(s) in RCA: 188] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Revised: 09/24/2015] [Accepted: 09/25/2015] [Indexed: 01/14/2023]
Abstract
Long noncoding RNAs (lncRNAs) are emerging as important regulators of developmental pathways. However, their roles in human cardiac precursor cell (CPC) remain unexplored. To characterize the long noncoding transcriptome during human CPC cardiac differentiation, we profiled the lncRNA transcriptome in CPCs isolated from the human fetal heart and identified 570 lncRNAs that were modulated during cardiac differentiation. Many of these were associated with active cardiac enhancer and super enhancers (SE) with their expression being correlated with proximal cardiac genes. One of the most upregulated lncRNAs was a SE-associated lncRNA that was named CARMEN, (CAR)diac (M)esoderm (E)nhancer-associated (N)oncoding RNA. CARMEN exhibits RNA-dependent enhancing activity and is upstream of the cardiac mesoderm-specifying gene regulatory network. Interestingly, CARMEN interacts with SUZ12 and EZH2, two components of the polycomb repressive complex 2 (PRC2). We demonstrate that CARMEN knockdown inhibits cardiac specification and differentiation in cardiac precursor cells independently of MIR-143 and -145 expression, two microRNAs located proximal to the enhancer sequences. Importantly, CARMEN expression was activated during pathological remodeling in the mouse and human hearts, and was necessary for maintaining cardiac identity in differentiated cardiomyocytes. This study demonstrates therefore that CARMEN is a crucial regulator of cardiac cell differentiation and homeostasis.
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Affiliation(s)
- Samir Ounzain
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland.
| | - Rudi Micheletti
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Carme Arnan
- Bioinformatics and Genomics Group, Centre for Genomic Regulation, Barcelona, Spain
| | - Isabelle Plaisance
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Dario Cecchi
- Bioinformatics and Genomics Group, Centre for Genomic Regulation, Barcelona, Spain
| | - Blanche Schroen
- Centre for Heart Failure Research, Cardiovascular Research Institute, Maastricht University, The Netherlands
| | - Ferran Reverter
- Bioinformatics and Genomics Group, Centre for Genomic Regulation, Barcelona, Spain
| | - Michael Alexanian
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Christine Gonzales
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Shi Yan Ng
- Stem Cell and Developmental Biology Group, Genome Institute of Singapore, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
| | - Giovanni Bussotti
- Comparative Bioinformatics Group, Centre for Genomic Regulation, Barcelona, Spain
| | - Iole Pezzuto
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Cedric Notredame
- Comparative Bioinformatics Group, Centre for Genomic Regulation, Barcelona, Spain
| | - Stephane Heymans
- Centre for Heart Failure Research, Cardiovascular Research Institute, Maastricht University, The Netherlands
| | - Roderic Guigó
- Bioinformatics and Genomics Group, Centre for Genomic Regulation, Barcelona, Spain
| | - Rory Johnson
- Bioinformatics and Genomics Group, Centre for Genomic Regulation, Barcelona, Spain.
| | - Thierry Pedrazzini
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland.
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Fluri SMP, Pedrazzini T, Ruchat P, Pruvot E, Gonzales C, Plaisance I, Locca D. Fate of human crardiac precursoe cells following injection in the sheep myocardium using a NOGA cell delivery system. Cytotherapy 2014. [DOI: 10.1016/j.jcyt.2014.01.137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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10
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Nemir M, Metrich M, Plaisance I, Lepore M, Cruchet S, Berthonneche C, Sarre A, Radtke F, Pedrazzini T. The Notch pathway controls fibrotic and regenerative repair in the adult heart. Eur Heart J 2012; 35:2174-85. [PMID: 23166366 PMCID: PMC4139705 DOI: 10.1093/eurheartj/ehs269] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Aims In the adult heart, Notch signalling regulates the response to injury. Notch inhibition leads to increased cardiomyocyte apoptosis, and exacerbates the development of cardiac hypertrophy and fibrosis. The role of Notch in the mesenchymal stromal cell fraction, which contains cardiac fibroblasts and cardiac precursor cells, is, however, largely unknown. In the present study, we evaluate, therefore, whether forced activation of the Notch pathway in mesenchymal stromal cells regulates pathological cardiac remodelling. Methods and results We generated transgenic mice overexpressing the Notch ligand Jagged1 on the surface of cardiomyocytes to activate Notch signalling in adjacent myocyte and non-myocyte cells. In neonatal transgenic mice, activated Notch sustained cardiac precursor and myocyte proliferation after birth, and led to increased numbers of cardiac myocytes in adult mice. In the adult heart under pressure overload, Notch inhibited the development of cardiomyocyte hypertrophy and transforming growth factor-β/connective tissue growth factor-mediated cardiac fibrosis. Most importantly, Notch activation in the stressed adult heart reduced the proliferation of myofibroblasts and stimulated the expansion of stem cell antigen-1-positive cells, and in particular of Nkx2.5-positive cardiac precursor cells. Conclusions We conclude that Notch is pivotal in the healing process of the injured heart. Specifically, Notch regulates key cellular mechanisms in the mesenchymal stromal cell population, and thereby controls the balance between fibrotic and regenerative repair in the adult heart. Altogether, these findings indicate that Notch represents a unique therapeutic target for inducing regeneration in the adult heart via mobilization of cardiac precursor cells.
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Affiliation(s)
- Mohamed Nemir
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Rue du Bugnon 27, CH-1011 Lausanne, Switzerland
| | - Mélanie Metrich
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Rue du Bugnon 27, CH-1011 Lausanne, Switzerland
| | - Isabelle Plaisance
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Rue du Bugnon 27, CH-1011 Lausanne, Switzerland
| | - Mario Lepore
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Rue du Bugnon 27, CH-1011 Lausanne, Switzerland
| | - Steeve Cruchet
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Rue du Bugnon 27, CH-1011 Lausanne, Switzerland
| | - Corinne Berthonneche
- Cardiovascular Assessment Facility, University of Lausanne, Lausanne, Switzerland
| | - Alexandre Sarre
- Cardiovascular Assessment Facility, University of Lausanne, Lausanne, Switzerland
| | - Freddy Radtke
- Swiss Institute for Experimental Cancer Research, Swiss Federal Institute of Technology, Lausanne, Switzerland
| | - Thierry Pedrazzini
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Rue du Bugnon 27, CH-1011 Lausanne, Switzerland Cardiovascular Assessment Facility, University of Lausanne, Lausanne, Switzerland
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11
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Häuselmann SP, Rosc-Schlüter BI, Lorenz V, Plaisance I, Brink M, Pfister O, Kuster GM. β1-Integrin is up-regulated via Rac1-dependent reactive oxygen species as part of the hypertrophic cardiomyocyte response. Free Radic Biol Med 2011; 51:609-18. [PMID: 21620958 DOI: 10.1016/j.freeradbiomed.2011.05.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 05/06/2011] [Accepted: 05/09/2011] [Indexed: 11/21/2022]
Abstract
β(1)-Integrin mediates cardiomyocyte growth and survival and its proper regulation is essential for the structural and functional integrity of the heart. β(1)-Integrin expression is enhanced in hypertrophy, but the mechanism and significance of its up-regulation are unknown. Because reactive oxygen species (ROS) are important mediators of myocardial remodeling we examined their role in regulated β(1)-integrin expression. Hypertrophy was induced in neonatal cardiomyocytes by endothelin-1 (ET-1), which activated the regulatory NADPH oxidase subunit Rac1, evoked ROS, and enhanced fetal gene expression and cardiomyocyte size. ET-1 also enhanced cell adhesion and FAK phosphorylation and inhibited oxidative stress-induced cardiomyocyte apoptosis. Further, ET-1 increased β(1)-integrin mRNA and protein expression via Rac1-ROS-dependent MEK/ERK and EGF receptor-PI3K/Akt activation as shown by adenoviral dominant-negative Rac1 or overexpression of copper/zinc-superoxide dismutase. The relevance of regulated β(1)-integrin expression was examined in cardiomyocytes, in which targeting siRNA impeded the ET-1-induced β(1)-integrin up-regulation. In these cells, ET-1-induced cell adhesion, FAK phosphorylation, and hypertrophic response were significantly blunted, whereas its antiapoptotic effect was predominantly unchanged, suggesting at least partial dissociation of prohypertrophic and prosurvival signaling elicited by ET-1. In conclusion, β(1)-integrin up-regulation in response to ET-1 is mediated via Rac1-ROS-dependent activation of prohypertrophic pathways and is mandatory for ET-1-induced FAK activation, cell adhesion, and hypertrophic response.
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Affiliation(s)
- Stéphanie P Häuselmann
- Myocardial Research, Department of Biomedicine, University Hospital Basel and University of Basel, 4031 Basel, Switzerland
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12
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Shende P, Plaisance I, Morandi C, Pellieux C, Berthonneche C, Zorzato F, Krishnan J, Lerch R, Hall MN, Rüegg MA, Pedrazzini T, Brink M. Cardiac raptor ablation impairs adaptive hypertrophy, alters metabolic gene expression, and causes heart failure in mice. Circulation 2011; 123:1073-82. [PMID: 21357822 DOI: 10.1161/circulationaha.110.977066] [Citation(s) in RCA: 182] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Cardiac hypertrophy involves growth responses to a variety of stimuli triggered by increased workload. It is an independent risk factor for heart failure and sudden death. Mammalian target of rapamycin (mTOR) plays a key role in cellular growth responses by integrating growth factor and energy status signals. It is found in 2 structurally and functionally distinct multiprotein complexes called mTOR complex (mTORC) 1 and mTORC2. The role of each of these branches of mTOR signaling in the adult heart is currently unknown. METHODS AND RESULTS We generated mice with deficient myocardial mTORC1 activity by targeted ablation of raptor, which encodes an essential component of mTORC1, during adulthood. At 3 weeks after the deletion, atrial and brain natriuretic peptides and β-myosin heavy chain were strongly induced, multiple genes involved in the regulation of energy metabolism were altered, but cardiac function was normal. Function deteriorated rapidly afterward, resulting in dilated cardiomyopathy and high mortality within 6 weeks. Aortic banding-induced pathological overload resulted in severe dilated cardiomyopathy already at 1 week without a prior phase of adaptive hypertrophy. The mechanism involved a lack of adaptive cardiomyocyte growth via blunted protein synthesis capacity, as supported by reduced phosphorylation of ribosomal S6 kinase 1 and 4E-binding protein 1. In addition, reduced mitochondrial content, a shift in metabolic substrate use, and increased apoptosis and autophagy were observed. CONCLUSIONS Our results demonstrate an essential function for mTORC1 in the heart under physiological and pathological conditions and are relevant for the understanding of disease states in which the insulin/insulin-like growth factor signaling axis is affected such as diabetes mellitus and heart failure or after cancer therapy.
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Affiliation(s)
- Pankaj Shende
- Department of Biomedicine, University of Basel and University Hospital Basel, Hebelstrasse 20, CH-4031 Basel, Switzerland
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13
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Derangeon M, Bourmeyster N, Plaisance I, Pinet-Charvet C, Chen Q, Duthe F, Popoff MR, Sarrouilhe D, Hervé JC. RhoA GTPase and F-actin dynamically regulate the permeability of Cx43-made channels in rat cardiac myocytes. J Biol Chem 2008; 283:30754-65. [PMID: 18667438 DOI: 10.1074/jbc.m801556200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gap junctions are clusters of transmembrane channels allowing a passive diffusion of ions and small molecules between adjacent cells. Connexin43, the main channel-forming protein expressed in ventricular myocytes, can associate with zonula occludens-1, a scaffolding protein linked to the actin cytoskeleton and to signal transduction molecules. The possible influence of Rho GTPases, major regulators of cellular junctions and of the actin cytoskeleton, in the modulation of gap junctional intercellular communication (GJIC) was examined. The activation of RhoA by cytoxic necrotizing factor 1 markedly enhanced GJIC, whereas its specific inhibition by the Clostridium botulinum C3 exoenzyme significantly reduced it. RhoA activity affects GJIC without major cellular redistribution of junctional plaques or changes in the Cx43 phosphorylation pattern. As these GTPases frequently act via the cortical cytoskeleton, the importance of F-actin in the modulation of GJIC was investigated by means of agents interfering with actin polymerization. Cytoskeleton stabilization by phalloidin slowed down the kinetics of channel rundown in the absence of ATP, whereas its disruption by cytochalasin D rapidly and markedly reduced GJIC despite ATP presence. Cytoskeleton stabilization by phalloidin markedly reduced the consequences of RhoA activation or inactivation. This mechanism appears to be the first described capable to both up- or down-regulate GJIC through RhoA activation or, conversely, inhibition. The inhibition of Rho downstream kinase effectors had no effect on GJIC. The present results provide further insight into the gating and regulation of junctional channels and identify a new downstream target for the small G-protein RhoA.
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Affiliation(s)
- Mickaël Derangeon
- Institut de Physiologie et Biologie Cellulaires, Université de Poitiers, F-86022 Poitiers, France
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14
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Plaisance I, Morandi C, Brink M. TNF-α activates protein synthesis in neonatal rat ventricular cardiomyocytes through NF-κB and PI3-kinase. J Mol Cell Cardiol 2008. [DOI: 10.1016/j.yjmcc.2008.02.257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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15
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Plaisance I, Morandi C, Brink M. IGF-I-induced AKT activation abolishes TNF-α/p38-mediated increases in atrogin-1 gene expression in muscle. J Mol Cell Cardiol 2008. [DOI: 10.1016/j.yjmcc.2008.02.258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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16
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Plaisance I, Morandi C, Murigande C, Brink M. TNF-alpha increases protein content in C2C12 and primary myotubes by enhancing protein translation via the TNF-R1, PI3K, and MEK. Am J Physiol Endocrinol Metab 2008; 294:E241-50. [PMID: 17971516 DOI: 10.1152/ajpendo.00129.2007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent evidence supports that TNF-alpha, long considered a catabolic factor, may also have a physiological function in skeletal muscle. The catabolic view, mainly based on correlative studies in human and in vivo animal models, was challenged by experiments with myoblasts, in which TNF-alpha induced differentiation. The biological effects of TNF-alpha in differentiated muscle, however, remain poorly understood. In the present study, we tested whether TNF-alpha has growth-promoting effects in myotubes, and we characterized the mechanisms leading to these effects. Treatment of C(2)C(12) myotubes with TNF-alpha for 24 h increased protein synthesis (PS) and enhanced cellular dehydrogenase activity by 22 and 26%, respectively, without changing cell numbers. These effects were confirmed in myotubes differentiated from primary rat myoblasts. TNF-alpha activated two signaling cascades: 1) ERK1/2 and its target eIF4E and 2) Akt and its downstream effectors GSK-3, p70(S6K), and 4E-BP1. TNF-alpha-induced phosphorylation of Akt, and ERK1/2 was inhibited by an antibody against TNF-alpha receptor 1 (TNF-R1). PD-98059 pretreatment abolished TNF-alpha-induced phosphorylation of ERK1/2 and eIF4E, whereas PS was only partially inhibited. LY-294002 completely abolished TNF-alpha-induced stimulation of PS as well as phosphorylation of Akt and its downstream targets GSK-3, p70(S6K), and 4E-BP1. Rapamycin inhibited TNF-alpha-induced phosphorylation of the mTOR C1 target p70(S6K) without altering TNF-alpha-induced PS and 4E-BP1 phosphorylation. In conclusion, our results provide evidence that TNF-alpha enhances PS in myotubes and that this is based on enhanced protein translation mediated by the TNF-R1 and PI3K-Akt and MEK-ERK signaling cascades.
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Affiliation(s)
- Isabelle Plaisance
- Institute of Physiology, Department of Biomedicine, University and University Hospital of Basel, Basel, Switzerland
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17
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Hervé JC, Plaisance I, Loncarek J, Duthe F, Sarrouilhe D. Is the junctional uncoupling elicited in rat ventricular myocytes by some dephosphorylation treatments due to changes in the phosphorylation status of Cx43? Eur Biophys J 2004; 33:201-10. [PMID: 14745523 DOI: 10.1007/s00249-003-0381-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2003] [Revised: 12/04/2003] [Accepted: 12/09/2003] [Indexed: 11/24/2022]
Abstract
Gap junctions, specialized membrane structures that mediate cell-to-cell communication in almost all animal tissues, are composed of channel-forming integral membrane proteins termed connexins. Most of them, particularly connexin43 (Cx43), the most ubiquitous connexin, the major connexin present in cardiac myocytes, are phosphoproteins. Connexin phosphorylation has been thought to regulate gap junctional protein trafficking, gap junction assembly, channel gating, and turnover. Some connexins, including Cx43, show mobility shifts in gel electrophoresis when cells are exposed to phosphorylating or dephosphorylating treatments. However, after exposure of rat cardiac myocytes to different uncoupling dephosphorylating agents such as H7 or butanedione monoxime, no modification in the Cx43 phosphorylation profile was generally observed. The lack of direct correlation between the inhibition of cell-to-cell communication and changes in the phosphorylation pattern of Cx43 or, conversely, modifications of the latter without modifications of the intercellular coupling degree, suggest that the functional state of junctional channels might rather be determined by regulatory proteins associated with Cx43. The modulation of the activity of junctional channels by protein phosphorylation/dephosphorylation processes very likely requires (as for several other membrane channels) the formation of a multiprotein complex, where pore-forming subunits bind to auxiliary proteins (e.g. scaffolding proteins, enzymes, cytoskeleton elements) that play essential roles in channel localization and activity. Such regulatory proteins, behaving as targets for phosphorylation/dephosphorylation catalysers, might in particular control the open probability of junctional channels. A schematic illustration of the regulation of Cx43-made channels by protein phosphorylation involving a partner phosphoprotein is proposed.
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Affiliation(s)
- Jean-Claude Hervé
- Equipe Communications Jonctionnelles, Unité Mixte de Recherche CNRS 6558, Faculté de Sciences Fondamentales et Appliquées, Université de Poitiers, 40 avenue du R. Pineau, 86022 Poitiers, France.
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18
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Plaisance I, Duthe F, Sarrouilhe D, Hervé JC. The metabolic inhibitor antimycin A can disrupt cell-to-cell communication by an ATP- and Ca(2+)-independent mechanism. Pflugers Arch 2003; 447:181-94. [PMID: 14504927 DOI: 10.1007/s00424-003-1158-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2003] [Revised: 06/27/2003] [Accepted: 07/24/2003] [Indexed: 12/20/2022]
Abstract
In cardiac myocytes of new-born rats, the degree of intercellular communication through gap junctional channels closely depends on the metabolic state of the cells. In contrast, in stably transfected HeLa cells expressing rat cardiac connexin43 (Cx43, the main channel-forming protein present in ventricular myocytes), a major part of junctional communication persisted in ATP-depleted conditions, in the presence of a metabolic inhibitor (KCN) or of a broad spectrum inhibitor of protein kinases (H7). However, another metabolic inhibitor, antimycin A, which like cyanide inhibits electron transfer in the respiratory chain, totally interrupted cell-to-cell communication between Cx43-HeLa cells, even in whole-cell conditions, when ATP (5 mM) was present. Antimycin A caused a modest increase in cytosolic calcium concentration; however, junctional uncoupling still occurred when this rise was prevented. Conditions of ischemic insult (e.g. ischemia or chemical hypoxia) frequently cause the activation of protein kinases, particularly of Src and MAP kinases, and such activations are known to markedly disrupt gap junctional communication. Antimycin-induced junctional uncoupling occurred even in the presence of inhibitors of these kinases. Antimycin A appears able to cause junctional uncoupling either through the ATP depletion it induces as a metabolic poison or via a direct action on gap junction constituents.
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Affiliation(s)
- Isabelle Plaisance
- Communications Jonctionnelles, UMR CNRS 6558, Faculté de Sciences Fondamentales et Appliquées, Université de Poitiers, 40 avenue du R. Pineau, 86022 Poitiers, France
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Duthe F, Plaisance I, Sarrouilhe D, Hervé JC. Endogenous protein phosphatase 1 runs down gap junctional communication of rat ventricular myocytes. Am J Physiol Cell Physiol 2001; 281:C1648-56. [PMID: 11600429 DOI: 10.1152/ajpcell.2001.281.5.c1648] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gap junctional channels are essential for normal cardiac impulse propagation. In ventricular myocytes of newborn rats, channel opening requires the presence of ATP to allow protein kinase activities; otherwise, channels are rapidly deactivated by the action of endogenous protein phosphatases (PPs). The lack of influence of Mg(2+) and of selective PP2B inhibition is not in favor of the involvements of Mg(2+)-dependent PP2C and PP2B, respectively, in the loss of channel activity. Okadaic acid (1 microM) and calyculin A (100 nM), both inhibitors of PP1 and PP2A activities, significantly retarded the loss of channel activity. However, a better preservation was obtained in the presence of selective PP1 inhibitors heparin (100 microg/ml) or protein phosphatase inhibitor 2 (I2; 100 nM). Conversely, the stimulation of endogenous PP1 activity by p-nitrophenyl phosphate, in the presence of ATP, led to a progressive fading of junctional currents unless I2 was simultaneously added. Together, these results suggest that a basal phosphorylation-dephosphorylation turnover regulates gap junctional communication which is rapidly deactivated by PP1 activity when the phosphorylation pathway is hindered.
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Affiliation(s)
- F Duthe
- Physiologie Cellulaire, Unité Mixte de Recherche Centre National de Recherche Scientifique 6558, Université de Poitiers, 86022 Poitiers, France
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20
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Duthe F, Dupont E, Verrecchia F, Plaisance I, Severs NJ, Sarrouilhe D, Hervé JC. Dephosphorylation agents depress gap junctional communication between rat cardiac cells without modifying the Connexin43 phosphorylation degree. Gen Physiol Biophys 2000; 19:441-9. [PMID: 11409846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
The functional state of gap junctional channels and the phosphorylation status of Connexine43 (Cx43), the major gap junctional protein in rat heart, were evaluated in primary cultures of neonatal rat cardiomyocytes. H7, able to inhibit a range of serine/threonine protein kinases, progressively reduced gap junctional conductance to approximately 13% of its initial value within 10 min except when protein phosphatase inhibitors were also present. The dephosphorylating agent 2,3-Butanedione monoxime (BDM) produced both a quick and reversible interruption of cell-to-cell communication as well as a parallel slow inhibition of junctional currents. The introduction of a non-hydrolysable ATP analogue (ATPgammaS) in the cytosol delayed the second component, suggesting that it was the consequence of protein dephosphorylation. Western blot analysis reveals 2 forms of Cx43 with different electrophoretic mobilities which correspond to its known phosphorylated and dephosphorylated forms. After exposure of the cells to H7 (1 mmol/l, 1h) or BDM (15 mmol/l, 15 min), no modification in the level of Cx43 phosphorylation was observed. The lack of direct correlation between the inhibition of cell-to-cell communication and changes in the phosphorylation status of Cx43 suggest that the functional state of junctional channels might rather be determined by regulatory proteins associated to Cx43.
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Affiliation(s)
- F Duthe
- Physiologie Cellulaire, UMR CNRS 6558, Poitiers, France
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