Effect of TFAP4 overexpression on CF function
Cardiac fibrosis, is a common pathophysiologic process in nearly all heart diseases, leading to cardiac dysfunction and heart failure subsequently. The transition of cardiac fibroblasts (CFs) to a myofibroblast state underlies the cardiac fibrotic response, and this process is accompanied by changes in the cardiac mechanical environment. Mechanical forces play a central role in the initiation and propagation of fibrosis, resulting in further ECM deposition, crosslinking and reorganization, leading to adverse ventricular remodeling. However, the key factors regulating mechanotransduction during cardiac fibrosis remain unknown. Here we discovered that transcription factor activating enhancer-binding protein 4 (Tfap4) regulates CF migration and proliferation. Further investigation revealed that Tfap4 correlates with heart disease and is significantly upregulated in the fibrotic hearts. We demonstrated that Tfap4 overexpression stimulated CF activation, whereas Tfap4 knockdown resulted in the opposite effect. In addition, we also knocked down Tfap4 in primary human CF (HCFs) with consistent results. Silence of Tfap4 by lentivirus carrying Tfap4 shRNA markedly enhanced functional improvement and scar size reduction in myocardial infarction (MI) mice. Mechanistically, we found that Tfap4 exerts pro-fibrotic function by regulating mechanical stress. Unexpectedly, we found that Tfap4 is a regulator of mechanosensors, Itga11 and Piezo2, thereby involved in mechanotransduction that acts as a bistable switch for the CF phenotypic transition associated with cardiac fibrosis. Taken together, our study revealed that Tfap4 plays an important role in cardiac fibrosis. Overall design: To elucidate the underlying mechanisms by which Tfap4 promotes cardiac fibroblast activation, we performed bulk RNA-sequencing analyses of the CFs treated with Tfap4 overexpression after 3 days infection. Compared with Control, Tfap4 overexpression-treated cells showed 534 commonly upregulated genes and 476 commonly downregulated genes (FC>1.5, pvalue<0.05)