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Front. Cardiovasc. Med. | doi: 10.3389/fcvm.2019.00170

Differences in miR29 and Pro-fibrotic Gene Expression in Mouse and Human Hypertrophic Cardiomyopathy

 Yamin Liu1, 2, Junaid Afzal1, 2, Styliani Vakrou2,  Gabriela V. Greenland1, 2,  C. C. Talbot3, 4, Virginia B. Hebl5, Yufan Guan2,  Rehan Karmali1,  Jil C. Tardiff6,  Leslie A. Leinwand7, Jeffrey E. Olgin1,  Samarjit Das8,  Ryuya Fukunaga9* and  M. R. Abraham1, 2*
  • 1Hypertrophic Cardiomyopathy Center of Excellence, Division of Cardiology, University of California, San Francisco, United States
  • 2Hypertrophic Cardiomyopathy Center of Excellence, Johns Hopkins University, United States
  • 3The Johns Hopkins Hospital, Johns Hopkins Medicine, United States
  • 4Institute for Basic Biomedical Sciences, School of Medicine, Johns Hopkins University, United States
  • 5Intermountain Heart Institute, Intermountain Medical Center, United States
  • 6Sarver Heart Center, University of Arizona Health Sciences, United States
  • 7Biofrontiers Institute, Molecular, Cellular and Developmental Biology, University of Colorado Boulder, United States
  • 8Anesthesiology and Critical Care Medicine, Johns Hopkins University, United States
  • 9Department of Biological Chemistry, The Johns Hopkins Hospital, Johns Hopkins Medicine, United States

Background: Hypertrophic cardiomyopathy (HCM) is characterized by myocyte hypertrophy and fibrosis. Studies in 2 mouse models (R92W-TnT/R403Q-MyHC) at early HCM stage revealed upregulation of endothelin (ET1) signaling in both mutants, but TGFβ signaling only in TnT mutants. Dysregulation of miR29 expression has been implicated in cardiac fibrosis. But it is unknown whether expression of miR29a/b/c and profibrotic genes is commonly regulated in mouse and human HCM.
Methods: In order to understand mechanisms underlying fibrosis in HCM, and examine similarities/differences in expression of miR29a/b/c and several profibrotic genes in mouse and human HCM, we performed parallel studies in rat cardiac myocyte/fibroblast cultures, examined gene expression in 2 mouse models of (non-obstructive) HCM (R92W-TnT, R403Q-MyHC)/controls at early (5wks) and established (24wks) disease stage, and analyzed publicly available mRNA/miRNA expression data from obstructive-HCM patients undergoing septal myectomy/controls (unused donor hearts).
Myocyte cultures: ET1 increased superoxide/H2O2, stimulated TGFβ expression/secretion and suppressed miR29a expression in myocytes. The effect of ET1 on miR29 and TGFβ expression/secretion was antagonized by N-acetyl-cysteine, a reactive oxygen species scavenger.
Fibroblast cultures: ET1 had no effect on pro-fibrotic gene expression in fibroblasts. TGFβ1/TGFβ2 suppressed miR29a and increased collagen expression, which was abolished by miR29a overexpression.
Mouse and human HCM: Expression of miR29a/b/c was lower, and TGFB1/collagen gene expression was higher in TnT mutant-LV at 5&24 weeks; no difference was observed in expression of these genes in MyHC mutant-LV and in human myectomy tissue. TGFB2 expression was higher in LV of both mutant mice and human myectomy tissue. ACE2, a negative regulator of the renin-angiotensin-aldosterone system, was the most upregulated transcript in human myectomy tissue. Pathway analysis predicted upregulation of the anti-hypertrophic/anti-fibrotic liver X receptor/retinoid X receptor (LXR/RXR) pathway only in human myectomy tissue.
Conclusions: Our in vitro studies suggest that activation of ET1 signaling in cardiac myocytes increases reactive oxygen species and stimulates TGFβ secretion, which downregulates miR29a and increases collagen in fibroblasts, thus contributing to fibrosis. Our gene expression studies in mouse and human HCM reveal allele-specific differences in miR29 family/profibrotic gene expression in mouse HCM, and activation of anti-hypertrophic/anti-fibrotic genes and pathways in human HCM.

Keywords: hypertrophic cardiomyopathy, miR29, TGF-beta, collagen, mouse, humans, hypertrophic cardiomyopathy, miR29, TGF-beta, collagen, mouse, humans, hypertrophic cardiomyopathy, miR29, TGF-beta, Mouse, Humans

Received: 06 Jun 2019; Accepted: 08 Nov 2019.

Copyright: © 2019 Liu, Afzal, Vakrou, Greenland, Talbot, Hebl, Guan, Karmali, Tardiff, Leinwand, Olgin, Das, Fukunaga and Abraham. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Dr. Ryuya Fukunaga, The Johns Hopkins Hospital, Johns Hopkins Medicine, Department of Biological Chemistry, Baltimore, Maryland, United States,
Dr. M. R. Abraham, University of California, San Francisco, Hypertrophic Cardiomyopathy Center of Excellence, Division of Cardiology, San Francisco, United States,