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Intracellular Angiotensin‐II Interacts With Nuclear Angiotensin Receptors in Cardiac Fibroblasts and Regulates RNA Synthesis, Cell Proliferation, and Collagen Secretion
BACKGROUND: Cardiac fibroblasts play important functional and pathophysiological roles. Intracellular (“intracrine”) angiotensin‐II (Ang‐II) signaling regulates intercellular communication, excitability, and gene expression in cardiomyocytes; however, the existence and role of intracrine Ang‐II sign...
Autores principales: | , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
John Wiley and Sons Inc.
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5533010/ https://www.ncbi.nlm.nih.gov/pubmed/28381466 http://dx.doi.org/10.1161/JAHA.116.004965 |
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author | Tadevosyan, Artavazd Xiao, Jiening Surinkaew, Sirirat Naud, Patrice Merlen, Clémence Harada, Masahide Qi, Xiaoyan Chatenet, David Fournier, Alain Allen, Bruce G. Nattel, Stanley |
author_facet | Tadevosyan, Artavazd Xiao, Jiening Surinkaew, Sirirat Naud, Patrice Merlen, Clémence Harada, Masahide Qi, Xiaoyan Chatenet, David Fournier, Alain Allen, Bruce G. Nattel, Stanley |
author_sort | Tadevosyan, Artavazd |
collection | PubMed |
description | BACKGROUND: Cardiac fibroblasts play important functional and pathophysiological roles. Intracellular (“intracrine”) angiotensin‐II (Ang‐II) signaling regulates intercellular communication, excitability, and gene expression in cardiomyocytes; however, the existence and role of intracrine Ang‐II signaling in cardiac fibroblasts is unstudied. Here, we evaluated the localization of Ang‐II receptors on atrial fibroblast nuclei and associated intracrine effects of potential functional significance. METHODS AND RESULTS: Immunoblots of subcellular protein‐fractions from isolated canine atrial fibroblasts indicated the presence of nuclear Ang‐II type 1 receptors (AT1Rs) and Ang‐II type 2 receptors (AT2Rs). Fluorescein isothiocyanate–Ang‐II binding displaceable by AT1R‐ and AT2R‐blockers was present on isolated fibroblast nuclei. G‐protein subunits, including Gαq/11, Gαi/3, and Gβ, were observed in purified fibroblast nuclear fractions by immunoblotting and intact‐fibroblast nuclei by confocal immunocytofluorescence microscopy. Nuclear AT1Rs and AT2Rs regulated de novo RNA synthesis ([α(32)P]UTP incorporation) via IP3R‐ and NO‐dependent pathways, respectively. In intact cultured fibroblasts, intracellular Ang‐II release by photolysis of a membrane‐permeable caged Ang‐II analog led to IP3R‐dependent nucleoplasmic Ca(2+)‐liberation, with IP3R3 being the predominant nuclear isoform. Intracellular Ang‐II regulated fibroblast proliferation ([(3)H]thymidine incorporation), collagen‐1A1 mRNA‐expression, and collagen secretion. Intracellular Ang‐II and nuclear AT1R protein levels were significantly increased in a heart failure model in which atrial fibrosis underlies atrial fibrillation. CONCLUSIONS: Fibroblast nuclei possess AT1R and AT2R binding sites that are coupled to intranuclear Ca(2+)‐mobilization and NO liberation, respectively. Intracellular Ang‐II signaling regulates fibroblast proliferation, collagen gene expression, and collagen secretion. Heart failure upregulates Ang‐II intracrine signaling‐components in atrial fibroblasts. These results show for the first time that nuclear angiotensin‐II receptor activation and intracrine Ang‐II signaling control fibroblast function and may have pathophysiological significance. |
format | Online Article Text |
id | pubmed-5533010 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | John Wiley and Sons Inc. |
record_format | MEDLINE/PubMed |
spelling | pubmed-55330102017-08-14 Intracellular Angiotensin‐II Interacts With Nuclear Angiotensin Receptors in Cardiac Fibroblasts and Regulates RNA Synthesis, Cell Proliferation, and Collagen Secretion Tadevosyan, Artavazd Xiao, Jiening Surinkaew, Sirirat Naud, Patrice Merlen, Clémence Harada, Masahide Qi, Xiaoyan Chatenet, David Fournier, Alain Allen, Bruce G. Nattel, Stanley J Am Heart Assoc Original Research BACKGROUND: Cardiac fibroblasts play important functional and pathophysiological roles. Intracellular (“intracrine”) angiotensin‐II (Ang‐II) signaling regulates intercellular communication, excitability, and gene expression in cardiomyocytes; however, the existence and role of intracrine Ang‐II signaling in cardiac fibroblasts is unstudied. Here, we evaluated the localization of Ang‐II receptors on atrial fibroblast nuclei and associated intracrine effects of potential functional significance. METHODS AND RESULTS: Immunoblots of subcellular protein‐fractions from isolated canine atrial fibroblasts indicated the presence of nuclear Ang‐II type 1 receptors (AT1Rs) and Ang‐II type 2 receptors (AT2Rs). Fluorescein isothiocyanate–Ang‐II binding displaceable by AT1R‐ and AT2R‐blockers was present on isolated fibroblast nuclei. G‐protein subunits, including Gαq/11, Gαi/3, and Gβ, were observed in purified fibroblast nuclear fractions by immunoblotting and intact‐fibroblast nuclei by confocal immunocytofluorescence microscopy. Nuclear AT1Rs and AT2Rs regulated de novo RNA synthesis ([α(32)P]UTP incorporation) via IP3R‐ and NO‐dependent pathways, respectively. In intact cultured fibroblasts, intracellular Ang‐II release by photolysis of a membrane‐permeable caged Ang‐II analog led to IP3R‐dependent nucleoplasmic Ca(2+)‐liberation, with IP3R3 being the predominant nuclear isoform. Intracellular Ang‐II regulated fibroblast proliferation ([(3)H]thymidine incorporation), collagen‐1A1 mRNA‐expression, and collagen secretion. Intracellular Ang‐II and nuclear AT1R protein levels were significantly increased in a heart failure model in which atrial fibrosis underlies atrial fibrillation. CONCLUSIONS: Fibroblast nuclei possess AT1R and AT2R binding sites that are coupled to intranuclear Ca(2+)‐mobilization and NO liberation, respectively. Intracellular Ang‐II signaling regulates fibroblast proliferation, collagen gene expression, and collagen secretion. Heart failure upregulates Ang‐II intracrine signaling‐components in atrial fibroblasts. These results show for the first time that nuclear angiotensin‐II receptor activation and intracrine Ang‐II signaling control fibroblast function and may have pathophysiological significance. John Wiley and Sons Inc. 2017-04-05 /pmc/articles/PMC5533010/ /pubmed/28381466 http://dx.doi.org/10.1161/JAHA.116.004965 Text en © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs (http://creativecommons.org/licenses/by-nc-nd/4.0/) License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made. |
spellingShingle | Original Research Tadevosyan, Artavazd Xiao, Jiening Surinkaew, Sirirat Naud, Patrice Merlen, Clémence Harada, Masahide Qi, Xiaoyan Chatenet, David Fournier, Alain Allen, Bruce G. Nattel, Stanley Intracellular Angiotensin‐II Interacts With Nuclear Angiotensin Receptors in Cardiac Fibroblasts and Regulates RNA Synthesis, Cell Proliferation, and Collagen Secretion |
title | Intracellular Angiotensin‐II Interacts With Nuclear Angiotensin Receptors in Cardiac Fibroblasts and Regulates RNA Synthesis, Cell Proliferation, and Collagen Secretion |
title_full | Intracellular Angiotensin‐II Interacts With Nuclear Angiotensin Receptors in Cardiac Fibroblasts and Regulates RNA Synthesis, Cell Proliferation, and Collagen Secretion |
title_fullStr | Intracellular Angiotensin‐II Interacts With Nuclear Angiotensin Receptors in Cardiac Fibroblasts and Regulates RNA Synthesis, Cell Proliferation, and Collagen Secretion |
title_full_unstemmed | Intracellular Angiotensin‐II Interacts With Nuclear Angiotensin Receptors in Cardiac Fibroblasts and Regulates RNA Synthesis, Cell Proliferation, and Collagen Secretion |
title_short | Intracellular Angiotensin‐II Interacts With Nuclear Angiotensin Receptors in Cardiac Fibroblasts and Regulates RNA Synthesis, Cell Proliferation, and Collagen Secretion |
title_sort | intracellular angiotensin‐ii interacts with nuclear angiotensin receptors in cardiac fibroblasts and regulates rna synthesis, cell proliferation, and collagen secretion |
topic | Original Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5533010/ https://www.ncbi.nlm.nih.gov/pubmed/28381466 http://dx.doi.org/10.1161/JAHA.116.004965 |
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