A TGF-β1/LEF1/β-catenin/JLP network motif regulates autophagy and tubule injury in renal fibrosis
Chen Li, Meng Zhang, Maoqing Tian, Zeyu Tang, Yuying Hu, Yuyu Long, Xiaofei Wang, Liwen Qiao, Jiefei Zeng, Yujuan Wang, Xinghua Chen, Cheng Chen, Xiaoyan Li, Lu Zhang, Huiming Wang
Chen Li, Meng Zhang, Maoqing Tian, Zeyu Tang, Yuying Hu, Yuyu Long, Xiaofei Wang, Liwen Qiao, Jiefei Zeng, Yujuan Wang, Xinghua Chen, Cheng Chen, Xiaoyan Li, Lu Zhang, Huiming Wang
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Research Article Cell biology Nephrology

A TGF-β1/LEF1/β-catenin/JLP network motif regulates autophagy and tubule injury in renal fibrosis

Abstract

Sustained injury to renal tubular epithelial cells (TECs), driven by excessive autophagy, is a critical mechanism underlying kidney fibrosis. Our previous work identified JLP — a TEC-expressed scaffolding protein — as an endogenous antifibrotic factor that counteracts TGF-β1–induced autophagy and fibrogenesis. However, the mechanism underlying JLP downregulation in renal fibrosis remains unclear. Here, we delineated a TGF-β1/LEF1/β-catenin/JLP axis that governs TEC autophagy through a dichotomous regulatory circuit. Under physiological conditions, low levels of β-catenin and LEF1 with minimal nuclear localization permitted normal JLP expression, which in turn maintained autophagy in check. In contrast, during renal injury, TGF-β1 promoted the expression and nuclear translocation of β-catenin and LEF1, which together suppressed JLP transcription. This loss of JLP-mediated inhibition led to unchecked autophagy and exacerbated fibrotic damage. Analyses of kidney tissues from patients with CKD, murine fibrotic kidneys, and cultured HK-2 cells confirmed consistent JLP downregulation accompanied by upregulation and nuclear accumulation of LEF1 and β-catenin. Therapeutic intervention using the β-catenin/LEF1 inhibitor iCRT3 or LEF1-targeted silencing in murine fibrosis models restored JLP expression, attenuated TEC autophagy, and ameliorated renal fibrosis. These findings revealed an autoregulatory circuit controlling TEC autophagy and fibrogenesis, and supported LEF1 and β-catenin as potential therapeutic targets in CKD.

Authors

Chen Li, Meng Zhang, Maoqing Tian, Zeyu Tang, Yuying Hu, Yuyu Long, Xiaofei Wang, Liwen Qiao, Jiefei Zeng, Yujuan Wang, Xinghua Chen, Cheng Chen, Xiaoyan Li, Lu Zhang, Huiming Wang

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Figure 8

Pharmacological inhibition of LEF1 reduces TEC injury and attenuates UUO-induced renal fibrosis.

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Pharmacological inhibition of LEF1 reduces TEC injury and attenuates UUO...
(A) Schematic of experimental design. Wild-type C57BL/6 mice (8–10 weeks old, male) underwent UUO surgery and were administered daily i.p. injections of iCRT3 (10 mg/kg/d) for 2 weeks. (B) Gross appearance of kidneys from the indicated groups. Scale bars: 5 mm. (C) H&E, Masson’s trichrome, and Sirius red staining of kidney tissues from the indicated group. (D–F) Quantification of tubular damage score, and tubulointerstitial fibrosis percentage (n = 6 mice per group). Scale bars: 50 μm. (G) Western blot analysis and quantitative data of fibronectin, collagen I, LC3, Beclin-1, p62, and JLP of kidney tissues in the indicated groups (n = 6 mice per group). (H and I) Schematic illustration of the TGF-β1/LEF1/β-catenin/JLP axis in renal fibrosis. In response to TGF-β1 stimulation, the transcription factor LEF1 is specifically upregulated in tubular epithelial cells. LEF1 binds to the promoter region of the JLP gene (SPAG9), suppressing its transcription and expression. JLP, an intrinsic antifibrotic factor, as previously identified by our group, counteracts TGF-β1–induced fibrosis. The inhibition of JLP leads to the sustained activation of TGF-β1 signaling and persistent autophagy in TECs, which exacerbates cellular injury and accelerates the progression of renal fibrosis. TGF-β1 induces β-catenin translocation from the plasma membrane to the nucleus and interacts with LEF1, partially enhancing LEF1 transcriptional activity. The absence of LEF1, achieved through either TEC-specific knockout, AAV9-mediated gene therapy, or pharmacological inhibition of activity, effectively prevents the loss of JLP under fibrotic conditions. This preservation of JLP leads to suppression of sustained autophagy and attenuation of renal fibrosis. Statistical analysis was performed 1-way ANOVA with Tukey’s multiple-comparison test (D–G). Data are mean ± SD.