Abstract: TH-PO569

Increased Wnt/β-Catenin Signaling in Postnatal Mouse Model of ADPKD

Session Information

Category: Genetic Diseases of the Kidney

  • 801 Cystic Kidney Diseases

Authors

  • Jung, Yun Joon, Boston Children's Hospital, Boston, Massachusetts, United States
  • Kreidberg, Jordan A., Boston Children's Hospital, Boston, Massachusetts, United States
Background

The Wnt signaling pathway has an important role for nephron development and elevated expression of β-Catenin, master regulator of the Wnt pathway, is shown to correlate with cystogenesis in autosomal dominant polycystic kidney disease (ADPKD). We previously demonstrated increased expression of Wnt7a and 7b in an embryonic mouse model of ADPKD. Here we provide further evidence that β-catenin is elevated in a postnatal model of ADPKD using Hoxb7-Cre-IRES-eGFP;Pkd1flox/flox mice.

Methods

To understand the contribution of Wnt signaling in ADPKD, we measured β-Catenin expression, in vivo and in vitro, using cystic kidneys of Hoxb7-Cre-IRES-eGFP;Pkd1flox/flox mice and Hoxb7-Cre-IRES-eGFP;Pkd1flox/+ controls and then used immunofluorescence and nuclear/cytoplasmic fractionation to quantify levels of β-Catenin with Western blotting at relevant subcellular locations. The use of two small molecules targeted the interaction of β-Catenin with p300 and CBP (Creb binding protein) and allowed us to measure, in vitro, the effect on the expression of Fibronectin and alpha smooth muscle actin (αSMA).

Results

Kidneys from Hoxb7-Cre-IRES-eGFP;Pkd1flox/flox develop cysts beginning at postnatal day 3 and have overwhelming cystogenesis by postnatal day 21. Nuclear b-catenin was evident in cyst lining cells of cystic kidneys at postnatal day 7. The expression of Tcf-1, a b-catenin target gene, was elevated in postnatal kidneys as further evidence of hyperactivation of the canonical Wnt pathway. Fibronectin and αSMA expression were also increased in cystic kidneys. Inhibition of the β-catenin-CBP with ICG-001 decreased expression of fibronectin and αSMA, suggesting that they are expressed downstream of the Wnt/b-catenin pathway.

Conclusion

The canonical Wnt pathway appears to be hyperactivated in mouse models of ADPKD and may serve as a therapeutic target to decrease cyst formation.

Funding

  • NIDDK Support