Abstract
Overactivation of cardiac fibroblasts (CFs) is one of the main causes of myocardial fibrosis (MF), and inhibition of CF activation is a crucial strategy for MF therapy. A previous study by our group demonstrated that leonurine (LE) effectively inhibits collagen synthesis and myofibroblast generation originated from CFs, and eventually mitigates the progression of MF (where miR-29a-3p is likely to be a vital mediator). However, the underlying mechanisms involved in this process remain unknown. Thus, the present study aimed to investigate the precise role of miR-29a-3p in LE-treated CFs, and to elucidate the pharmacological effects of LE on MF. Neonatal rat CFs were isolated and stimulated by angiotensin II (Ang II) to mimic the pathological process of MF in vitro. The results show that LE distinctly inhibits collagen synthesis, as well as the proliferation, differentiation and migration of CFs, all of which could be induced by Ang II. In addition, LE promotes apoptosis in CFs under Ang II stimulation. During this process, the down-regulated expressions of miR-29a-3p and p53 are partly restored by LE. Either knockdown of miR-29a-3p or inhibition of p53 by PFT-α (a p53 inhibitor) blocks the antifibrotic effect of LE. Notably, PFT-α suppresses miR-29a-3p levels in CFs under both normal and Ang II-treated conditions. Furthermore, ChIP analysis confirmed that p53 is bound to the promoter region of miR-29a-3p, and directly regulates its expression. Overall, our study demonstrates that LE upregulates p53 and miR-29a-3p expression, and subsequently inhibits CF overactivation, suggesting that the p53/miR-29a-3p axis may play a crucial role in mediating the antifibrotic effect of LE against MF.