IJMS, Vol. 23, Pages 15423: miR−122−5p Regulates Renal Fibrosis In Vivo (International Journal of Molecular Sciences)

The role of exogenous microRNAs (miRNAs) in renal fibrosis is poorly understood. Here, the effect of exogenous miRNAs on renal fibrosis was investigated using a renal fibrosis mouse model generated by unilateral ureteral obstruction (UUO). miRNA microarray analysis and quantitative reverse-transcription polymerase chain reaction showed that miR−122−5p was the most downregulated (0.28-fold) miRNA in the kidneys of UUO mice. The injection of an miR−122−5p mimic promoted renal fibrosis and upregulated COL1A2 and FN1, whereas an miR−122−5p inhibitor suppressed renal fibrosis and downregulated COL1A2 and FN1. The expression levels of fibrosis-related mRNAs, which were predicted targets of miR−122−5p, were evaluated. The expression level of TGFBR2, a pro-fibrotic mRNA, was upregulated by the miR−122−5p mimic, and the expression level of FOXO3, an anti−fibrotic mRNA, was upregulated by the miR−122−5p inhibitor. The protein expressions of TGFBR2 and FOXO3 were confirmed by immunohistochemistry. Additionally, the expression levels of LC3, downstream anti-fibrotic mRNAs of FOXO3, were upregulated by the miR−122−5p inhibitor. These results suggest that miR−122−5p has critical roles in renal fibrosis.