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Kidney Week

Abstract: FR-PO952

New Organoid Model for ADPKD Reveals Pkd2 Loss Disrupts Apical Junctional Complex and Master Scaffold Ezrin

Session Information

Category: Genetic Diseases of the Kidney

  • 1001 Genetic Diseases of the Kidney: Cystic

Authors

  • Dixon, Eryn E., University of Maryland School of Medicine, Baltimore, Maryland, United States
  • Woodward, Owen M., University of Maryland School of Medicine, Baltimore, Maryland, United States
Background

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressive cystogenesis, resulting in end stage renal disease. This common monogenetic disorder is attributed to loss of function mutations in the genes, PKD1 and PKD2, that encode for transmembrane proteins, polycystin 1 and 2. Hallmark components of cystogenesis, including increased proliferation, changes in apicobasolateral compartmentalization, and a secretory phenotype, suggest a defect in the organization of renal epithelial cells following PKD1/2 loss.

Methods

Immunofluorescent morphometric analysis of nephrectomized kidney tissue from ADPKD patients recently revealed significant changes in the morphology of the apical compartment, demarcated by zonula occludens 1 (ZO-1), in small, emerging cysts, when compared to normal tubules. Additionally, transepithelial electrical resistance assays using inducible Pkd2 Cre (Pkd2 Pax8 rtTA TetOCre +mTmG) primary cells suggest that inactivation of Pkd2 results in a decrease in resistance, indicating disruption of junctional integrity.

Results

While many pathways have been implicated in the complex progression of cystogenesis, these results suggest disruption of the apical junctional complex (AJC), may be responsible for changes in the organization and compartmentalization of apical proteins and signaling. Using a new in vitro tubule model system designed to investigate the initiation of cyst formation directly following the loss of functional polycystin 2 (PC2), we have demonstrated that loss of PC2 results in a decrease in master scaffold of apical compartment organization, ezrin. Furthermore, an inducible Pkd2 Cre mouse model demonstrates that ezrin loss can be recapitulated in vivo following inactivation of Pkd2 with doxycycline. Human ADPKD cystic tissue exhibits a decrease in ezrin protein abundance relative to normal kidneys and aberrant localization in cyst walls.

Conclusion

Therefore, the initiation of cystogenesis in ADPKD may be dependent on PC2’s regulation of the AJC and master scaffold, ezrin, highlighting a novel function of PC2 in renal epithelial cells.

Funding

  • NIDDK Support