Introduction: Although renal fibrosis is observed in chronic kidney disease, there is still no effective treatment for it. Our previous study has shown that protein arginine methyltransferase 5 (PRMT5) is essential for transforming growth factor-β (TGF-β)-induced transcription of fibrotic genes in cardiac fibroblasts. In this study, we aimed to investigate the function of PRMT5 in renal fibrosis.
Methods: NRK-49f kidney fibroblast cells were stimulated with TGF-β for 48 hours. PRMT5 expression levels were examined by qPCR and Western blotting (WB). Next, NRK-49f cells were transfected with siRNA of PRMT5 followed by TGF-β stimulation and mRNA levels of myofibroblast marker α-smooth muscle actin (α-SMA) and fibrotic genes (Col3a1, CTGF) were investigated by qPCR. Finally, NRK-49f cells were treated with EPZ015666, a selective inhibitor of PRMT5 for 2 hours and then stimulated with TGF-β. The expression levels of α-SMA were examined by qPCR and WB.
Results: qPCR and WB revealed that the expression levels of PRMT5 were upregulated by TGF-β stimulation. The expressions of α-SMA and the fibrosis-related genes were upregulated by TGF-β stimulation, whereas knockdown of PRMT5 suppressed the upregulation of these genes. TGF-β-induced increase in α-SMA was suppressed by treatment with EPZ015666.
Conclusion: Knockdown and pharmacological inhibition of PRMT5 suppressed TGF-β-induced myofibroblast differentiation in kidney fibroblasts. These results suggest that PRMT5 is an essential molecule for TGF-β-induced fibrotic response in kidney fibroblasts.