MicroRNA-22 Is a Master Regulator of Bone Morphogenetic Protein-7/6 Homeostasis in the Kidney

Jianyin Long,Shawn S Badal,Yin Wang,Benny H.J Chang,Antony Rodriguez,Farhad R Danesh

doi:10.1074/jbc.m113.498634

Abstract

Accumulating evidence suggests that microRNAs (miRNAs) contribute to a myriad of kidney diseases. However, the regulatory role of miRNAs on the key molecules implicated in kidney fibrosis remains poorly understood. Bone morphogenetic protein-7 (BMP-7) and its related BMP-6 have recently emerged as key regulators of kidney fibrosis. Using the established unilateral ureteral obstruction (UUO) model of kidney fibrosis as our experimental model, we examined the regulatory role of miRNAs on BMP-7/6 signaling. By analyzing the potential miRNAs that target BMP-7/6 in silica, we identified miR-22 as a potent miRNA targeting BMP-7/6. We found that expression levels of BMP-7/6 were significantly elevated in the kidneys of the miR-22 null mouse. Importantly, mice with targeted deletion of miR-22 exhibited attenuated renal fibrosis in the UUO model. Consistent with these in vivo observations, primary renal fibroblast isolated from miR-22-deficient UUO mice demonstrated a significant increase in BMP-7/6 expression and their downstream targets. This phenotype could be rescued when cells were transfected with miR-22 mimics. Interestingly, we found that miR-22 and BMP-7/6 are in a regulatory feedback circuit, whereby not only miR-22 inhibits BMP-7/6, but miR-22 by itself is induced by BMP-7/6. Finally, we identified two BMP-responsive elements in the proximal region of miR-22 promoter. These findings identify miR-22 as a critical miRNA that contributes to renal fibrosis on the basis of its pivotal role on BMP signaling cascade.

Highlights

BMPs have emerged as key regulators of kidney fibrosis
We uncover a critical role of miR-22 on BMP signaling and renal fibrosis by providing strong evidence that miR-22 directly targets Bone morphogenetic protein-7 (BMP-7), BMP-6, and BMPR1B
C, HeLa cells were co-transfected with empty vector (Vector) and three independent plasmids expressing either 3.1-luc-Bmp7, -Bmp6, or -Bmpr1b wild type 3Ј-UTR (WT-UTR) or a 3.1-luc-Bmp7 mutant 3Ј UTR (BMP-7 mut) and the indicated control mimic (Ctrl mimic) or miR-22 mimic

Summary

Background

BMPs have emerged as key regulators of kidney fibrosis. Results: Deletion of miR-22 attenuated renal fibrosis via direct targeting of BMP-7/6. Mice with targeted deletion of miR-22 exhibited attenuated renal fibrosis in the UUO model Consistent with these in vivo observations, primary renal fibroblast isolated from miR-22-deficient UUO mice demonstrated a significant increase in BMP-7/6 expression and their downstream targets. We identified two BMPresponsive elements in the proximal region of miR-22 promoter These findings identify miR-22 as a critical miRNA that contributes to renal fibrosis on the basis of its pivotal role on BMP signaling cascade. Using the established unilateral ureteral obstruction (UUO) mouse model of renal fibrosis as our experimental model, we found that miR-22 deletion attenuates kidney fibrosis in vivo by targeting BMP-7/6 and BMP receptor type I receptor (BMPR1B). We identified two BREs in the miR-22 promoter region, which are responsible for the transcriptional regulation of BMP-7/6 on miR-22 expression

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION

Methods