Background: microRNAs (miRs) have been reported to regulate cell biological functions. To explore the underlying mechanism of miR-21 involvement in patients with atrial fibrosis and atrial fibrillation (AF).
Methods: In total, 49 patients (24 AF, sinus rhythm 25) aged 33-68 years old, including heart valve replacement surgery and cardiac catheterisation. The pathological changes and collagen depositions was analysed by Masson's Trichrome Staining. miR-21, TGF-β1, Smad2, p-Smad2, WWP-1, collagen I and collagen III expression were analysed by Western blotting, qRT-PCR, miR one step qRT-PCR, respectively. Treatment human cardiac fibroblasts with TGF-β1, qRT-PCR and Western blotting to find changes in miR-21, Smad2 and WWP-1 levels. Transfected human cardiac fibroblasts with miR-21 mimic and miR-21 inhibitor. Finally, cell proliferation ability was assessed by the MTT assay and flow cytometry.
Results: Compared to sinus rhythm (SR) group, the collagen volume fraction was significantly increased in AF patients. The levels of the TGF-β1, collagen I and collagen III were significantly elevated in AF group. In AF patients, the expression of miR-21 was increased, while the expression of WWP-1 was decreased. Transfected cardiac fibroblasts with miR-21 mimic increased miR-21 expression and decreased WWP-1 expression, whereas miR-21 inhibitor causes the opposite effects. Additionally, we demonstrated that knockdown miR-21 targeted up-regulation of WWP-1 may suppress cardiac fibroblasts proliferation.
Conclusion: These indicated that miR-21 inhibits cardiac fibroblasts proliferation by inactivating the TGF-β1/Smad2 signaling pathway via up-regulation of WWP-1.
Keywords: Atrial fibrosis; Cardiac fibroblast; MicroRNA-21; Smad 2; TGF-β1; WW domain-containing protein 1.
Copyright © 2017 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.