Cardiac reprogramming factor Gata4 reduces postinfarct cardiac fibrosis through direct repression of the profibrotic mediator snail

Abstract

Objective The administration of a variety of reprogramming factor cocktails has now been shown to reprogram cardiac fibroblasts into induced cardiomyocyte-like cells (iCMs). Reductions in ventricular fibrosis observed after reprogramming factor administration, however, seem to far exceed the extent of iCM generation in vivo. We therefore investigated whether reprogramming factor administration might primarily play a role in activating anti-fibrotic molecular pathways. Methods Adult rat cardiac fibroblasts (RCFs) were infected with lentivirus encoding the transcription factors Gata4, Mef2c or Tbx5, all three vectors (GMT) or a GFP control vector. Gene and protein expression assays were performed to identify relevant anti-fibrotic targets of these factors. The anti-fibrotic effects of these factors were then investigated in a rat coronary ligation model. Results GMT administration to RCFs in vitro significantly downregulated expression of Snail, and the pro-fibrotic factors, CTGF, Collagen1a1, and Fibronectin. Of these factors, Gata4 was shown to be the one responsible for the downregulation of the pro-fibrotic factors, and Snail (mRNA expression fold change relative to GFP for Snail, Gata4: 0.5 ± 0.3, Mef2c: 1.3 ± 1.0, Tbx5: 0.9 ± 0.5, GMT: 0.6 ± 0.2, p<0.05). ChIP qPCR identified Gata4 binding sites in the Snail promoter. In a rat coronary ligation model, only Gata4 administration alone also improved post– infarct ventricular function and also reduced the extent of post-infarct fibrosis. Conclusions Gata4 administration reduces post–infarct ventricular fibrosis and improves ventricular function in a rat coronary ligation model, potentially as a result of Gata4 mediated downregulation of the pro-fibrotic mediator Snail.

Maternal Exposure to High-Fat Diet Induces Long-Term Derepressive Chromatin Marks in the Heart

“…Not only, EZH2 represses gene through histone modification, but also methylates non-histone protein such as Gata-binding protein 4 (GATA4) [31]. GATA4 is a key transcription factor of heart development [32] and regulator of fibrosis [33]. GATA4 methylation by polycomb repressive complex (PRC) 2 results in reduced GATA4 transcriptional potency [31], indicating a potential additional role of EZH2 decrease in the cardiac fibrosis induced by maternal high-fat diet.…”

Targeting GATA4 for cardiac repair

“…Signaling pathways and regulatory mechanisms that are active during embryogenesis and are involved in heart growth and development may be used to repair the injured adult heart . The overexpression of cardiac GATA4 protein preserves cardiac function after cardiac injury by promoting increased angiogenesis and reduced fibrosis . Moreover, genetic enhancement of GATA4 protein was able to prevent cardiomyocyte apoptosis and drug‐induced cardiotoxicity .…”

“…7 The overexpression of cardiac GATA4 protein preserves cardiac function after cardiac injury by promoting increased angiogenesis and reduced fibrosis. [41][42][43] Moreover, genetic enhancement of GATA4 protein was able to prevent cardiomyocyte apoptosis and drug-induced cardiotoxicity. 44 A study by Malek Mohammadi et al demonstrated that high abundance of cardiac GATA4 by adenoviral gene transfer at postnatal days 1-7 markedly improved cardiac regeneration after cryoinjury and rescued the loss of regenerative capacity.…”

Molecular discoveries and treatment strategies by direct reprogramming in cardiac regeneration

“…Mathison et al 94 recently reported that Gata4 has antifibrotic function through downregulation of the profibrotic transcription factor Snail. They demonstrated that Gata4 expression alone is sufficient to decrease post-infarct cardiac fibrosis in a rat ligation model.…”

“…They suggest incorporation of Gata4 into reprogramming cocktails in vivo. 94 Further characterization of the function of Gata4 is necessary to elucidate mechanisms of improved cardiac function separate from its reprogramming effects.…”