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Suppression of Pro-fibrotic Signaling Potentiates Factor-mediated Reprogramming of Mouse Embryonic Fibroblasts into Induced Cardiomyocytes
Published on: June 3, 2018
Cardiac Reprogramming and Gata4 Overexpression Reduce Fibrosis and Improve Diastolic Dysfunction in Heart Failure
Yu Yamada1, Taketaro Sadahiro2, Koji Nakano1
1Department of Cardiology (Y.Y., K.N., S.H., Y.A., T.A., R.F.), University of Tsukuba, Japan.
Insights
Cardiac reprogramming using Gata4 overexpression in cardiac fibroblasts (CFs) shows promise for treating heart failure with preserved ejection fraction (HFpEF). This approach reduces fibrosis and improves diastolic dysfunction, offering a potential new therapy for HFpEF.
Area of Science:
- Cardiology
- Regenerative Medicine
- Fibrosis Research
Background:
- Heart failure with preserved ejection fraction (HFpEF) is a significant health concern characterized by cardiac fibrosis and diastolic dysfunction.
- Mechanisms driving fibrosis in HFpEF are not fully understood, and effective targeted therapies are lacking.
- Cardiac reprogramming, involving overexpression of Mef2c/Gata4/Tbx5/Hand2 (MGTH), has shown potential for myocardial infarction but its efficacy in HFpEF is unknown.
Purpose of the Study:
- To investigate the efficacy of cardiac reprogramming in a mouse model of HFpEF.
- To elucidate the mechanisms underlying cardiac fibrosis in HFpEF.
- To evaluate the therapeutic potential of individual reprogramming factors, particularly Gata4, in HFpEF.
Main Methods:
- Established HFpEF model mice using a high-fat diet and nitric oxide synthase inhibition.
- Utilized transgenic mice for tamoxifen-inducible MGTH overexpression in cardiac fibroblasts (CFs) for reprogramming and lineage tracing.
- Employed bulk RNA-sequencing, single-cell RNA-sequencing, and spatial transcriptomics to analyze fibrotic mechanisms and reprogramming effects.
- Investigated the impact of single reprogramming factors and their effects on human CFs.
Main Results:
- MGTH overexpression improved diastolic dysfunction, cardiac hypertrophy, fibrosis, inflammation, and capillary loss in HFpEF mice.
- Cardiac reprogramming converted approximately 1% of CFs into induced cardiomyocytes, upregulated heart contraction genes, and suppressed fetal gene programs and profibrotic signatures.
- Single-cell and spatial transcriptomics revealed MGTH reversed profibrotic changes in distinct CF clusters responsible for interstitial and perivascular fibrosis.
- Gata4 overexpression alone reduced fibrosis and improved diastolic dysfunction by suppressing CF activation without inducing new cardiomyocytes, and also suppressed profibrotic signatures in human CFs.
Conclusions:
- Overexpression of Gata4 in cardiac fibroblasts (CFs) presents a promising therapeutic strategy for HFpEF.
- Gata4-mediated reprogramming effectively suppresses cardiac fibrosis and ameliorates diastolic dysfunction in HFpEF.
- Targeting CF activation through Gata4 offers a potential new avenue for treating HFpEF.
Background:
Heart failure with preserved ejection fraction (HFpEF) is a major health concern. Pathological stimuli and interactions between cardiac fibroblasts (CFs) and other cell types may lead to cardiac fibrosis and diastolic dysfunction, which are hallmarks of HFpEF. Interstitial and perivascular cardiac fibrosis correlates with poor prognosis in HFpEF; however, mechanisms of fibrosis remain poorly elucidated, and targeted therapies are lacking. Cardiac reprogramming is a promising therapeutic approach for myocardial infarction that facilitates cardiac regeneration and antifibrosis action through Mef2c/Gata4/Tbx5/Hand2 (MGTH) overexpression in resident CFs. However, the efficacy of this approach on HFpEF is yet to be established.
Methods:
Herein, we examined the effects of cardiac reprogramming in HFpEF using Tcf21iCre/Tomato/MGTH2A transgenic mice, which expressed both MGTH and reporter expression in CFs for cardiac reprogramming and lineage tracing upon tamoxifen administration. To establish HFpEF model mice, we used a combination of a high-fat diet and nitric oxide synthase inhibition. Bulk RNA-sequencing, single-cell RNA-sequencing, and spatial transcriptomics were conducted to determine fibrotic mechanisms and the efficacy of cardiac reprogramming in HFpEF. We generated new tamoxifen-inducible transgenic mice overexpressing each reprogramming factor in CFs to investigate the effect of single factors. Last, we analyzed the effect of reprogramming factors in human CFs.
Results:
Cardiac reprogramming with MGTH overexpression improved diastolic dysfunction, cardiac hypertrophy, fibrosis, inflammation, and capillary loss in HFpEF. Cardiac reprogramming converted approximately 1% of resident CFs into induced cardiomyocytes. Bulk RNA-seq indicated that MGTH overexpression upregulated genes related to heart contraction and suppressed the fetal gene program (Nppa and Nppb) and proinflammatory and fibrotic signatures. Single-cell RNA-sequencing and spatial transcriptomics revealed that multiple CF clusters upregulated fibrotic genes to induce diffuse interstitial fibrosis, whereas distinct CF clusters generated focal perivascular fibrosis in HFpEF. MGTH overexpression reversed these profibrotic changes. Among 4 reprogramming factors, only Gata4 overexpression in CFs reduced fibrosis and improved diastolic dysfunction in HFpEF by suppressing CF activation without generating new induced cardiomyocytes. Gata4 overexpression also suppressed profibrotic signatures in human CFs.
Conclusions:
Overexpressing Gata4 in CFs may be a promising therapeutic approach for HFpEF by suppressing fibrosis and improving diastolic dysfunction.
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