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 3

IGF2BP3 is a downstream target of Wnt/β-catenin signaling.

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IGF2BP3 is a downstream target of Wnt/β-catenin signaling. (A) Bioinform...
(A) Bioinformatics analyses revealed the presence of putative TBSs in the promoter region of human, mouse, and rat IGF2BP3 gene. The sequences and positions of the putative TBSs were highlighted (red), whereas the TBS consensus sequence was given at the bottom of this panel. TBS, TCF/lymphoid enhancer factor binding site. (B–D) Wnt3a (100 ng/mL) induced active β-catenin and IGF2BP3 expression in HKC-8 cells in a time-dependent manner. Representative Western blot (B) and quantitative data (C and D). **P < 0.01 versus controls (n = 3, ANOVA with Student-Newman-Keuls test). (E–G) Wnt3a induced active β-catenin and IGF2BP3 expression in a dose-dependent fashion. Representative Western blot (E) and quantitative data (F and G). **P < 0.01 versus controls (n = 3, ANOVA with Student-Newman-Keuls test). (H) Immunofluorescence staining for IGF2BP3 expression after Wnt3a stimulation. Cells were stained for IGF2BP3 at 2 days after incubation with Wnt3a. Boxed areas were enlarged. Arrows indicate positive staining. Scale bar, 50 μm. (I) Western blots show IGF2BP3 distribution in cytosolic and nuclear fractions. α-Tubulin and TBP were probed to normalize cytosolic and nuclear fractions. (J and K) Representative Western blot (J) and quantitative data (K) show the expression of IGF2BP3 after various treatments. *P < 0.05 versus controls; †P < 0.05 versus pDel-β-cat group alone (n = 3, ANOVA with Student-Newman-Keuls test). (L–O) ICG-001 reduced renal expression of β-catenin, active β-catenin, and IGF2BP3 protein at 7 days after UUO. Representative Western blots (L) and quantitative data (M–O). **P < 0.01 versus sham; †P < 0.05, ††P < 0.01 versus the UUO injected with vehicle group (n = 5, ANOVA with Student-Newman-Keuls test). (P) Representative micrographs show IGF2BP3 protein in different groups as indicated. Arrows indicate positive staining. Scale bar, 50 μm. (Q) Quantitative determination of IGF2BP3 staining in different groups. **P < 0.01 versus sham; ††P < 0.01 versus the UUO injected with vehicle group (n = 5, ANOVA with Student-Newman-Keuls test).