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Published on: June 3, 2018
miR-15a-5p regulates myocardial fibrosis in atrial fibrillation by targeting Smad7
Dan He1,2, Zhong-Bao Ruan1,2, Gui-Xian Song1
1Department of Cardiology, Jiangsu Taizhou People's Hospital, Taizhou, China.
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.
Insights
MicroRNA-15a-5p (miR-15a-5p) is upregulated in atrial fibrillation (AF) and promotes myocardial fibrosis by inhibiting Smad7. Targeting the miR-15a-5p/Smad7 pathway may offer a novel therapeutic strategy for AF.
Area of Science:
- Cardiovascular Biology
- Molecular Medicine
- Fibrosis Research
Background:
- Myocardial fibrosis is a key pathological feature of atrial fibrillation (AF) with no effective treatments.
- MicroRNA-15a-5p (miR-15a-5p) is dysregulated in AF patients, but its role in cardiac fibrosis remains elusive.
Purpose of the Study:
- To elucidate the function of miR-15a-5p in the pathogenesis of myocardial fibrosis associated with AF.
- To investigate the regulatory relationship between miR-15a-5p and Smad7 in cardiac fibrosis.
Main Methods:
- Analysis of miR-15a-5p, Smad7, TGF-β1, and collagen I expression in AF patient tissues and LPS-stimulated H9C2 cells.
- In vitro manipulation of miR-15a-5p and Smad7 levels using mimics, inhibitors, and siRNA.
- Assessment of cell viability, proliferation, and fibrosis using CCK-8, EdU, hydroxyproline, and HE staining.
- Dual-luciferase reporter assays to confirm direct interaction between miR-15a-5p and Smad7.
Main Results:
- Upregulated miR-15a-5p, TGF-β1, and collagen I, with downregulated Smad7 observed in AF tissues and LPS-treated cells.
- miR-15a-5p directly targets and inhibits Smad7 expression.
- Inhibition of miR-15a-5p or augmentation of Smad7 attenuated LPS-induced cardiac fibrosis and cell proliferation.
Conclusions:
- The miR-15a-5p/Smad7 axis plays a critical role in regulating myocardial fibrosis in AF.
- This pathway represents a promising therapeutic target for mitigating cardiac fibrosis in atrial fibrillation.
