TGF-β1/LEF1/β-Catenin/JLP Network Motif Regulation of Autophagy and Tubule Injury in Renal Fibrosis

Background: Autophagy is a crucial cellular homeostasis mechanism responsible for the degradation of cytoplasmic components. Basal autophagy is essential for maintaining cellular integrity in proximal tubular cells. Nonetheless, sustained or excessive autophagy contribute to renal fibrosis by promoting tubular atrophy and interstitial inflammation. JLP (JNK-associated leucine zipper protein) serves as an intrinsic anti-fibrotic factor and has been demonstrated to counteract the pro-fibrotic effects induced by TGF-β1. LEF1, a transcription factor implicated in the Wnt and TGF-β1 signaling pathways, is involved in various pathological processes. The involvement of LEF1 in tubule cell dysfunction associated with in renal fibrosis remains to be elucidated. Methods: CHIP assays were conducted to evaluate the interaction between LEF1 and the JLP gene. LEF1 expression was assessed in human kidney biopsy samples. Two murine models of progressive chronic kidney disease (CKD), namely unilateral ureteral obstruction (UUO) and unilateral ischemia-reperfusion injury (uIRI), were employed to investigate the expression of LEF1 and JLP. A combination of genetic and pharmacological approaches, alongside cultured kidney tubular epithelial cells, was utilized to explore the underlying mechanisms. Results: LEF1 directly suppresses JLP expression by binding to its promoter region. In kidney biopsies from patients with CKD, as well as in murine models of UUO and uIRI, LEF1 expression was markedly elevated in tubular epithelial nuclei, whereas JLP expression was diminished in proximal tubular cells. Tubule-specific deletion of Lef1 or adeno-associated virus (AAV)-mediated inhibition of LEF1 restored JLP expression, suppressed autophagy, and alleviated tubulointerstitial fibrosis in fibrotic murine models. TGF-β1 induced pronounced autophagy in HK-2 cells with simultaneous knockdown of JLP and LEF1. Moreover, LEF1 activity is enhanced by β-catenin, and pharmacological inhibition of this pathway preserved JLP expression and mitigated kidney fibrosis. Conclusion: The TGF-β1/LEF1/β-catenin/JLP axis plays a regulatory role in tubular epithelial cell autophagy and renal fibrosis. Targeting LEF1 represents a promising therapeutic strategy for alleviating kidney fibrosis, highlighting novel molecular targets for clinical intervention.