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Suppression of Pro-fibrotic Signaling Potentiates Factor-mediated Reprogramming of Mouse Embryonic Fibroblasts into Induced Cardiomyocytes
Published on: June 3, 2018
MiR-34a induces myofibroblast differentiation from renal fibroblasts
Suguru Saito1, Shin-Ichiro Ohno2, Yuichirou Harada3
1Department of Nephrology, Tokyo Medical University, Tokyo, Japan.
Background:
Renal fibrosis is the common outcome of progressive kidney diseases. To avoid dialysis, the molecular mechanism of renal fibrosis must be explored further. MicroRNAs play key roles in renal fibrosis. MiR-34a is a transcriptional target of p53, which regulates the cell cycle and apoptosis. Previous studies demonstrated that miR-34a promotes renal fibrosis. However, the distinct roles of miR-34a in renal fibrosis have not been fully elucidated. Here, we identified the roles of miR-34a in renal fibrosis.
Method:
We first analyzed p53 and miR-34a expression in kidney tissues in s UUO (unilateral ureteral obstruction) mouse model. Then, to confirm the effects of miR-34a in vitro, we transfected a miR-34a mimic into a kidney fibroblast cell line (NRK-49F) and analyzed.
Results:
We found that the expression of p53 and miR-34a was upregulated after UUO. Furthermore, after transfection of the miR-34a mimic into kidney fibroblasts, the expression of α-SMA was upregulated dramatically. In addition, α-SMA upregulation was greater upon transfection of the miR-34a mimic than upon treatment with TGF-β1. Moreover, high expression of Acta2 was maintained despite sufficient removal of the miR-34a mimic by changing the medium 4 times during the 9-day culture. After transfection of the miR-34a mimic into kidney fibroblasts, we did not detect phospho-SMAD2/3 by immunoblotting analysis.
Conclusion:
Our study revealed that miR-34a induces myofibroblast differentiation from renal fibroblasts. Moreover, the miR-34a-induced upregulation of α-SMA was independent of the TGF-β/SMAD signaling pathway. In conclusion, our study indicated that the p53/miR-34a axis promotes the development of renal fibrosis.
Insights
MicroRNA-34a (miR-34a) drives renal fibrosis by inducing myofibroblast differentiation. This process, regulated by the p53/miR-34a axis, is independent of the TGF-β/SMAD pathway, offering new therapeutic targets.
Area of Science:
- Nephrology
- Molecular Biology
- Cell Biology
Background:
- Renal fibrosis is a common endpoint for progressive kidney diseases, necessitating further exploration of its molecular mechanisms to prevent dialysis.
- MicroRNAs, including miR-34a, are implicated in renal fibrosis, with miR-34a known to be regulated by p53 and involved in cell cycle and apoptosis.
- While previous studies suggest miR-34a promotes renal fibrosis, its precise roles require further elucidation.
Purpose of the Study:
- To investigate the specific roles of microRNA-34a (miR-34a) in the development of renal fibrosis.
- To explore the molecular mechanisms by which miR-34a influences renal fibroblast differentiation and extracellular matrix production.
Main Methods:
- Analysis of p53 and miR-34a expression in a unilateral ureteral obstruction (UUO) mouse model.
- In vitro experiments involving transfection of a miR-34a mimic into NRK-49F kidney fibroblast cells.
- Assessment of alpha-smooth muscle actin (α-SMA) and phospho-SMAD2/3 expression.
Main Results:
- p53 and miR-34a expression were upregulated in kidneys following UUO.
- Transfection with miR-34a mimic significantly upregulated α-SMA in kidney fibroblasts, exceeding the effect of TGF-β1 treatment.
- α-SMA upregulation persisted even after miR-34a mimic removal, and phospho-SMAD2/3 was not detected, indicating a TGF-β/SMAD-independent mechanism.
Conclusions:
- miR-34a induces myofibroblast differentiation from renal fibroblasts.
- The upregulation of α-SMA by miR-34a is independent of the TGF-β/SMAD signaling pathway.
- The p53/miR-34a axis plays a crucial role in promoting renal fibrosis development.
