Cited by 179Cardiac Fibrosis and RemodelingCongenital heart defects researchProtein Degradation and Inhibitors

Dynamic Chromatin Targeting of BRD4 Stimulates Cardiac Fibroblast Activation

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Stratton, Matthew S., Bagchi, Rushita A., Felisbino, Marina B., Hirsch, Rachel A., Smith, Harrison E., Riching, Andrew S., Enyart, Blake Y., Koch, Keith A. +10 more·2019·Circulation Research

Published version of a preprint

Abstract

Rationale: Small molecule inhibitors of the acetyl-histone binding protein BRD4 have been shown to block cardiac fibrosis in preclinical models of heart failure (HF). However, since the inhibitors target BRD4 ubiquitously, it is unclear whether this chromatin reader protein functions in cell type-specific manner to control pathological myocardial fibrosis. Furthermore, the molecular mechanisms by which BRD4 stimulates the transcriptional program for cardiac fibrosis remain unknown. Objective: We sought to test the hypothesis that BRD4 functions in a cell-autonomous and signal-responsive manner to control activation of cardiac fibroblasts, which are the major extracellular matrix-producing cells of the heart. Methods and Results: RNA-sequencing, mass spectrometry, and cell-based assays employing primary adult rat ventricular fibroblasts demonstrated that BRD4 functions as an effector of TGF-β (transforming growth factor-β) signaling to stimulate conversion of quiescent cardiac fibroblasts into Periostin ( Postn )-positive cells that express high levels of extracellular matrix. These findings were confirmed in vivo through whole-transcriptome analysis of cardiac fibroblasts from mice subjected to transverse aortic constriction and treated with the small molecule BRD4 inhibitor, JQ1. Chromatin immunoprecipitation-sequencing revealed that BRD4 undergoes stimulus-dependent, genome-wide redistribution in cardiac fibroblasts, becoming enriched on a subset of enhancers and super-enhancers, and leading to RNA polymerase II activation and expression of downstream target genes. Employing the Sertad4 (SERTA domain-containing protein 4) locus as a prototype, we demonstrate that dynamic chromatin targeting of BRD4 is controlled, in part, by p38 MAPK (mitogen-activated protein kinase) and provide evidence of a critical function for Sertad4 in TGF-β-mediated cardiac fibroblast activation. Conclusions: These findings define BRD4 as a central regulator of the pro-fibrotic cardiac fibroblast phenotype, establish a p38-dependent signaling circuit for epigenetic reprogramming in heart failure, and uncover a novel role for Sertad4 . The work provides a mechanistic foundation for the development of BRD4 inhibitors as targeted anti-fibrotic therapies for the heart.

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Crossref · 10.1161/circresaha.119.315125

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  • Cultured human primary cardiac and dermal fibroblasts and immortalized cardiac fibroblasts were relatively poor models of human cardiac fibroblast diversity under resting or stimulated conditions.

    “By contrast, cultured human primary cardiac and dermal fibroblasts and immortalized cardiac fibroblasts were relatively poor models of human cardiac fibroblast diversity under resting or stimulated (TGFβ (refs. 19,39,40), IL-1β (ref. 41)) conditions.”

    From Targeting immune–fibroblast cell communication in heart failure (2024) · cites this paper as [40]

    The Results section, “BRD4 inhibition blocks TGF-β-mediated cardiac fibroblast activation” (page unavailable), documents TGF-β stimulation of cultured primary adult rat ventricular fibroblasts. The cited paper therefore supports the stimulation condition, but not its application to cultured human fibroblasts. The assessment that the cultures were poor models of human cardiac fibroblast diversity is the citing authors’ own conclusion, not a finding established by this source. (LLM, conf=0.82)

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  • Primary human cardiac fibroblasts, primary human dermal fibroblasts, and immortalized human cardiac fibroblasts were relatively poor models of human cardiac fibroblast diversity under resting or stimulated (TGFβ, IL-1β) conditions.

    “In contrast, primary human cardiac fibroblasts, primary human dermal fibroblasts, and immortalized human cardiac fibroblasts were relatively poor models of human cardiac fibroblast diversity under resting or stimulated (TGFβ 20,33,34 , IL-1 β 35 ) conditions.”

    From Targeting the Immune-Fibrosis Axis in Myocardial Infarction and Heart Failure (2022) · cites this paper as [34]

    The Results section (‘BRD4 inhibition blocks TGF-β-mediated cardiac fibroblast activation’; page unavailable) confirms that the paper used TGF-β to stimulate cardiac fibroblasts. Those experiments used primary adult rat ventricular fibroblasts, however; the paper does not establish that the listed human cell types are poor models of human cardiac fibroblast diversity. (LLM, conf=0.84)

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  • BRD4 has specific importance in aspects of heart failure pathogenesis.

    “We previously showed the specific importance of BRD4 in aspects of heart failure pathogenesis4,25.”

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Authors
Stratton, M. S., Bagchi, R. A., Felisbino, M. B., Hirsch, R. A., Smith, H. E., Riching, A. S., Enyart, B. Y., Koch, K. A., Cavasin, M. A., Alexanian, M., Song, K., Qi, J., Lemieux, M. E., Srivastava, D., Lam, M. P. Y., Haldar, S. M., Lin, C. Y., & McKinsey, T. A.
Affiliations
  • University of Colorado Anschutz (US)
  • Baylor College of Medicine (US)
  • From the Department of Medicine, Division of Cardiology (M.S.S., R.A.B., M.B.F., A.S.R., B.Y.E., K.A.K., M.A.C., K.S., M.P.Y.L., T.A.M.), University of Colorado Anschutz Medical Campus, Aurora
  • Gladstone Institutes (US)
  • Dana-Farber Cancer Institute (US)
  • Bioinfo, Plantagenet, ON, Canada (M.E.L.)
  • Amgen (United States) (US)
Corresponding author
  • Stratton, Matthew S.
  • Bagchi, Rushita A.
Venue
Circulation Research
Published
2019-09-13
Volume
125
Issue
7
Pages
662-677
ISSN
  • 0009-7330 (ISSN-L)
  • 1524-4571
OpenAlex
W2967233606
Cited by
179
References
57
Citations by year
2026: 25 · 2025: 30 · 2024: 24 · 2023: 26 · 2022: 26 · 2021: 26 · 2020: 21
FWCI
13.18
Type
journal article
Language
en
Open access
Locations
  • Circulation Research (publishedVersion)
  • bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
  • eScholarship (California Digital Library) (submittedVersion)
Funders
  • National Science Foundation
  • American Heart Association (19POST34380603, 16SFRN31400013)
  • Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (216927)
  • National Institutes of Health (16SFRN31400013)
  • Canadian Institutes of Health Research (FRN216927)
  • National Institute on Aging (K01AG056848)
  • National Heart, Lung, and Blood Institute (K99HL127302, R00HL127302, F32HL126354, R01HL147558, R01HL116848, T32HL007822, R01HL127240, R01HL141278)
  • National Institute of General Medical Sciences (T32GM007635)
  • National Institute of Diabetes and Digestive and Kidney Diseases (R01DK119594)
Topics
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Cardiac Fibrosis and Remodeling
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Congenital heart defects research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Degradation and Inhibitors
Keywords
BRD4, cardiac fibroblast activation, myocardial fibrosis, heart failure, TGF-beta signaling, p38 MAPK, chromatin reader proteins, epigenetic reprogramming, JQ1, antifibrotic therapy, extracellular matrix, transverse aortic constriction
MeSH terms
Bromodomain Containing Proteins, Animals, Azepines, Cells, Cultured, Chromatin, Enhancer Elements, Genetic, Extracellular Matrix, Female, Fibrosis, Heart Failure, Heart Ventricles, Male, Mice, Inbred C57BL, Nuclear Proteins, Protein Binding, RNA Polymerase II, Transcription Factors, Triazoles, Cell Adhesion Molecules, Transforming Growth Factor beta, Rats, Sprague-Dawley, Epigenesis, Genetic, Intracellular Signaling Peptides and Proteins, p38 Mitogen-Activated Protein Kinases, Mice, Rats, Myofibroblasts, Transcriptome

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