Macrophage Migration Inhibitory Factor Promotes the Proliferation and Activation of Atrial Fibroblasts through the Src Kinase Signaling Pathway
WANG Hongli1, LI Zhiqiang2, LIU Fen1, FANG Binbin1, FAN Ping3*
This study aimed to investigate the role of MIF (macrophage migration inhibitory factor) in regulating the proliferation and activation of atrial fibroblasts through Src kinase. An atrial fibrillation-susceptible mouse model was first established using Ang II (angiotensin II). Western blot was performed to detect MIF expres sion and Src phosphorylation levels, and Sirius red staining was used to evaluate the effect of MIF knockout on atrial f ibrosis. Subsequently, primary cells were isolated from the atrial tissue of adult mice and characterized by immuno f luorescence. Cells were treated with recombinant MIF (rMIF, 20 ng/mL) and the Src kinase inhibitor PP1 for 24 and 48 h. Cell proliferation and activation were assessed using CCK-8 and EdU assays, while the expression of fibrosis related proteins was detected via immunofluorescence and Western blot. The results showed that MIF expression and Src phosphorylation were significantly elevated in atrial fibrillation mice. MIF knockout reduced Src phosphorylation and attenuated fibrosis. In vitro experiments showed that the isolated cells exhibited a characteristic profile of high vi mentin expression and low α-SMA (α-smooth muscle actin) expression, and were identified as atrial fibroblasts. rMIF significantly promoted the proliferation and activation of atrial fibroblasts, whereas PP1 effectively inhibited these effects. Furthermore, MIF activated Src kinase, upregulating the expression of fibrosis-related proteins including CO L3A1, COL1A1, MMP-2, and TGF-β1, and induced Smad2/3 phosphorylation. These effects were attenuated by PP1 treatment. In conclusion, MIF plays a key role in atrial fibroblast activation through the Src-Smad2/3 signaling axis.
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