Insulin-like growth factor 2 mRNA-binding protein 3 promotes kidney injury by regulating β-catenin signaling
Dongyan Song, … , Haiyan Fu, Youhua Liu
Dongyan Song, … , Haiyan Fu, Youhua Liu
Published December 15, 2022
Citation Information: JCI Insight. 2023;8(2):e162060. https://doi.org/10.1172/jci.insight.162060.
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Research Article Nephrology

Insulin-like growth factor 2 mRNA-binding protein 3 promotes kidney injury by regulating β-catenin signaling

Abstract

Wnt/β-catenin is a developmental signaling pathway that plays a crucial role in driving kidney fibrosis after injury. Activation of β-catenin is presumed to be regulated through the posttranslational protein modification. Little is known about whether β-catenin is also subjected to regulation at the posttranscriptional mRNA level. Here, we report that insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) plays a pivotal role in regulating β-catenin. IGF2BP3 was upregulated in renal tubular epithelium of various animal models and patients with chronic kidney disease. IGF2BP3 not only was a direct downstream target of Wnt/β-catenin but also was obligatory for transducing Wnt signal. In vitro, overexpression of IGF2BP3 in kidney tubular cells induced fibrotic responses, whereas knockdown of endogenous IGF2BP3 prevented the expression of injury and fibrosis markers in tubular cells after Wnt3a stimulation. In vivo, exogenous IGF2BP3 promoted β-catenin activation and aggravated kidney fibrosis, while knockdown of IGF2BP3 ameliorated renal fibrotic lesions after obstructive injury. RNA immunoprecipitation and mRNA stability assays revealed that IGF2BP3 directly bound to β-catenin mRNA and stabilized it against degradation. Furthermore, knockdown of IGF2BP3 in tubular cells accelerated β-catenin mRNA degradation in vitro. These studies demonstrate that IGF2BP3 promotes β-catenin signaling and drives kidney fibrosis, which may be mediated through stabilizing β-catenin mRNA. Our findings uncover a previously underappreciated dimension of the complex regulation of Wnt/β-catenin signaling and suggest a potential target for therapeutic intervention of fibrotic kidney diseases.

Authors

Dongyan Song, Jingyue Shang, Yinyi Long, Menghua Zhong, Li Li, Jiongcheng Chen, Yadie Xiang, Huishi Tan, Haili Zhu, Xue Hong, Fan Fan Hou, Haiyan Fu, Youhua Liu

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Figure 5

IGF2BP3 is required for mediating Wnt/β-catenin signaling in vitro.

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IGF2BP3 is required for mediating Wnt/β-catenin signaling in vitro. (A–J...
(A–J) Knockdown of IGF2BP3 inhibited Wnt/β-catenin signaling. HKC-8 cells were incubated with Wnt3a (100 ng/mL) in the presence of control siRNA or IGF2BP3-specific siRNA for 2 days, as indicated. Representative Western blot (A) and quantitative data for IGF2BP3 (B), β-catenin (C), active β-catenin (D), Snail1 (E), fibronectin (F), α-SMA (G), KIM-1 (H), p53 (I), and p16INK4A (J) are presented. *P < 0.05, **P < 0.01 versus controls; †P < 0.05, ††P < 0.01 versus the Wnt3a plus control siRNA group (n = 3, ANOVA with Student-Newman-Keuls test). (K) Immunofluorescence staining shows fibronectin expression after various treatments. HKC-8 cells were incubated with Wnt3a (100 ng/mL) in the presence of control siRNA or BP3 siRNA for 2 days as indicated. Arrows indicate positive staining. Scale bar, 50 μm. (L–R) Representative Western blots (L) and quantitative data show the expression of IGF2BP3 (M), active β-catenin (N), MMP-7 (O), fibronectin (P), p-H3 (Q), and p16INK4A (R). HKC-8 cells were pretreated with ICG-001 (10 μM) for 1 hour, then incubated with Wnt3a (100 ng/mL) for 2 days. *P < 0.05 versus controls; †P < 0.05, ††P < 0.01 versus the Wnt3a group (n = 3, ANOVA with Student-Newman-Keuls test). (S) Schematic presentation of reciprocal feed-forward activation loop between IGF2BP3 and β-catenin.