miR-15a-5p regulates myocardial fibrosis in atrial fibrillation by targeting Smad7

Dan He; Zhong-Bao Ruan; Gui-Xian Song; Ge-Cai Chen; Fei Wang; Mei-Xiang Wang; Mao-Kun Yuan; Li Zhu

doi:10.7717/peerj.12686

miR-15a-5p regulates myocardial fibrosis in atrial fibrillation by targeting Smad7

PeerJ. 2021 Dec 20:9:e12686. doi: 10.7717/peerj.12686. eCollection 2021.

Authors

Dan He^{1

2}, Zhong-Bao Ruan^{1

2}, Gui-Xian Song¹, Ge-Cai Chen¹, Fei Wang¹, Mei-Xiang Wang¹, Mao-Kun Yuan³, Li Zhu¹

Affiliations

¹ Department of Cardiology, Jiangsu Taizhou People's Hospital, Taizhou, China.
² Dalian Medical University Graduate School of Medicine, dalian, China.
³ Department of Cardiothoracic Surgery, Jiangsu Taizhou People's Hospital, Taizhou, China.

Abstract

Background: At present, there is no effective treatment for myocardial fibrosis in atrial fibrillation (AF). It is reported that miR-15a-5p is abnormally expressed in AF patients but its specific role remains unclear. This study aims to investigate the effect of miR-15a-5p in myocardial fibrosis.

Methods: Left atrial appendage (LAA) tissues were collected from AF and non-AF patients. In lipopolysaccharide (LPS) stimulated H9C2 cells, miR-15a-5p mimic, inhibitor, pcDNA3.1-Smad7 and small interfering RNA-Smad7 (siRNA-Smad7) were respectively transfected to up-regulate or down-regulate the intracellular expression levels of miR-15a-5p and Smad7. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot (WB) were used to determine the expression levels of miR-15a-5p, Smad7, transforming growth factor β1 (TGF-β1) and collagen I. Cell counting kit-8 (CCK-8) and ethylene deoxyuridine (EdU) were used to determine cell viability and proliferation capacity, respectively. Dual-luciferase was used to detect whether miR-15a-5p interacted with Smad7, hydroxyproline (HYP) and Hematoxylin-Eosin (HE) staining were used to detect tissue fibrosis.

Results: The expression levels of miR-15a-5p, TGF-β1 and collagen I were up-regulated, while Smad7 was down-regulated in AF tissues and LPS-stimulated cells. MiR-15a-5p mimic can inhibit the expression of Smad7, and the dual-luciferase experiment confirmed their interaction. MiR-15a-5p inhibitor or pcDNA3.1-Smad7 can inhibit LPS-induced fibrosis and cell proliferation, while siRNA-Smad7 can reverse the changes caused by miR-15a-5p inhibitor.

Conclusion: We combined clinical studies with LPS-stimulated H9C2 cell model to validate the role of miR-15a-5p in the regulation of Smad7 and fibrosis. Taken together, the miR-15a-5p/Smad7 pathway might be a potential target for AF therapy.

Keywords: Atrial fibrillation; MiR-15a-5p; Myocardial fibrosis; Smad7; TGF-β1.

Grants and funding

The study was supported by Jiangsu Provincial Medical Innovation Team (Grant No. CXTDB2017015), Jiangsu Commission of Health, China (Grant No. H201665) and the Six Talent Foundation of Jiangsu Province, China (Grant No. WSN-20). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.