LncRNA CFAR promotes cardiac fibrosis via the miR-449a-5p/LOXL3/mTOR axis

Cardiac fibrosis is one of the crucial pathological factors in the heart, and various cardiac conditions associated with excessive fibrosis can eventually lead to heart failure. However, the exact molecular mechanism of cardiac fibrosis remains unclear. In the present study, we show that a novel lncRNA that we named cardiac fibrosis-associated regulator (CFAR) is a profibrotic factor in the heart. CFAR was upregulated in cardiac fibrosis and its knockdown attenuated the expression of fibrotic marker genes and the proliferation of cardiac fibroblasts, thereby ameliorating cardiac fibrosis. Moreover, CFAR acted as a ceRNA sponge for miR-449a-5p and derepressed the expression of LOXL3, which we experimentally established as a target gene of miR-449a-5p. In contrast to CFAR, miR-449a-5p was found to be significantly downregulated in cardiac fibrosis, and artificial knockdown of miR-449a-5p exacerbated fibrogenesis, whereas overexpression of miR-449a-5p impeded fibrogenesis. Furthermore, we found that LOXL3 mimicked the fibrotic factor TGF-β1 to promote cardiac fibrosis by activating mTOR. Collectively, our study established CFAR as a new profibrotic factor acting through a novel miR-449a-5p/LOXL3/mTOR axis in the heart and therefore might be considered as a potential molecular target for the treatment of cardiac fibrosis and associated heart diseases.