Promotion of ß-catenin/Foxo1 signaling ameliorates renal interstitial fibrosis.

ABSTRACT

Transforming growth factor ß (TGF-ß) is the key cytokine involved in causing fibrosis through cross-talk with major profibrotic pathways. However, inhibition of TGF-ß to prevent fibrosis would also abrogate its anti-inflammatory and wound-healing effects. ß-catenin is a common co-factor in most TGF-ß signaling pathways. ß-catenin binds to T-cell factor (TCF) to activate profibrotic genes and binds to Forkhead box O (Foxo) to promote cell survival under oxidative stress. Using a proximity ligation assay in human kidney biopsies, we found that ß-catenin/Foxo interactions were higher in kidney with little fibrosis, whereas ß-catenin/TCF interactions were upregulated in the kidney of patients with fibrosis. We hypothesised that ß-catenin/Foxo is protective against kidney fibrosis. We found that Foxo1 protected against rhTGF-ß1-induced profibrotic protein expression using a CRISPR/cas9 knockout of Foxo1 or TCF1 in murine kidney tubular epithelial C1.1 cells. Co-administration of TGF-ß with a small molecule inhibitor of ß-catenin/TCF (ICG-001), protected against kidney fibrosis in unilateral ureteral obstruction. Collectively, our human, animal and in vitro findings suggest ß-catenin/Foxo as a therapeutic target in kidney fibrosis.