Cardiac fibrosis after myocardial infarction (MI) is mainly associated with cardiac fibroblasts and its differentiation is the key pathological process. However, the cellular mechanism of fibroblast-to-myofibroblast conversion has not been clarified and a deeper mechanistic understanding is needed. We found that miR-574-5p was up-regulated in TGF-beta-induced myofibroblast differentiation. Silencing transiently miR-574-5p in HCFs, we found that suppression of miR-574-5p decreased myofibroblasts differentiation as validated by expression levels of fibrosis related genes, EDU imaging assay, wound healing assay and transwell assays. Conversely, overexpression of miR-574-5p displayed opposite results. ARID3A was verified as a direct target gene of miR-574-5p and decreased level of ARID3A forced fibroblast-to-myofibroblast differentiation of TGF-beta-induced HCFs. Our data suggests that miR-574-5p plays a pivotal role in human cardiac fibroblasts (HCFs) myofibroblast differentiation and demonstrates that miR-574-5p and arid3a may be a novel therapeutic target for cardiac fibrosis. (C) 2019 Elsevier Inc. All rights reserved.