miR­152 regulates TGF­ß1­induced epithelial­mesenchymal transition by targeting HPIP in tubular epithelial cells.

Renal fibrosis is a common pathological feature of chronic kidney diseases, and their development and progression are influenced by epigenetic modifications including aberrant microRNA (miRNA or miR) expression. miRNAs have been demonstrated to modulate the aggressiveness of various cancers and have emerged as possible therapeutic agents for the management of renal fibrosis. Transforming growth factor ß1 (TGF­ß1)­induced epithelial­mesenchymal transition (EMT) of tubular epithelial cells serves a role in the initiation and progression of renal fibrosis. Furthermore, recent results indicated that the progression of EMT is reversible. The present study aimed to clarify the role of miR­152 in EMT of the tubular epithelial cell line HK­2, stimulated by TGF­ß1, using in vitro transfection with a miR­152 mimic and to further investigate the underlying mechanism of miR­152 activity. In the present study, miR­152 expression was significantly reduced in TGF­ß1­treated HK­2 cells, accompanied by an increased expression of hematopoietic pre­B­cell leukemia transcription factor (PBX)­interacting protein (HPIP). Additionally, miR­152 overexpression inhibited TGF­ß1­induced EMT and suppressed HPIP expression by directly targeting the 3' untranslated region of HPIP in HK­2 cells. Furthermore, upregulation of HPIP reversed miR­152­mediated inhibitory effects on the EMT. Collectively, the results suggest that downregulation of miR­152 initiates the dedifferentiation of renal tubules and progression of renal fibrosis, which may provide important targets for prevention strategies of renal fibrosis.

[MiR-155 Inhibits the Expression of MMPs in HK2 Cells by Targeting KLF4].

OBJECTIVES: To determine whether miR -155 inhibits the expression of matrix metalloproteinase 2 (MMP-2) and matrix metalloproteinase 9 (MMP-9) in HK2 cells by targeting Kruppel-like factor 4 (KLF4). METHODS: MiR -155-mimic, miR -155-NC empty plasmid, and culture medium were transfected into renal tubular epithelial cells, respectively. Six hours later, the expression of miR -155 was detected by real time-PCR; the expressions of MMP-2, MMP-9 and KLF4 were detected by Western blot; and the activity of MMP-2 and MMP-9 in the cells was detected by gelatin zymography. Because KLF4 was predicted as the target gene of miR -155 by bioinformatics. The miR-155 overexpressed HK2 cells were transfected with KLF4 overexpression plasmid or empty plasmid. Six hours later, the expressions of MMP-2, MMP-9 and KLF4, and the activity of MMP-2 and MMP-9 were measured again. Finally, cells containing luciferase plasmids with KLF4-3!d-UTR wild type (WT) or mutant (MUT) sequence were constructed and transfected with miR -155-mimic or empty plasmid. Luciferase assay was used to confirm whether KLF4 -3!d-UTR was the binding site in targeting miR -155#. RESULTS: Compared with the cells transfected with empty plasmid, the expression of miR -155 was up-regulated and the expressions of MMP-2, MMP-9 and KLF4 were down-regulated in the cells transfected with miR -155-mimic. Compared with the cells transfected with miR -155 mimic or miR -155 mimic+empty plasmid, the expressions of MMP-2, MMP-9 and KLF4 were up-regulated in the KLF4+miR -155 transfected cells. Luciferase assays confirmed that miR -155 binds to KLF4 , and KLF4 -3!d-UTR is the target gene of miR -155. CONCLUSION: MiR-155 inhibits the expressions of MMP-2 and MMP-9 in HK2 cells by targeting KLF4 -3!d-UTR.