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Abstract: FR-PO296

Changes in Tubule Flow During Renal Cyst Development

Session Information

Category: Genetic Diseases of the Kidneys

  • 1101 Genetic Diseases of the Kidneys: Cystic

Authors

  • Thomas, Isis, The University of Alabama at Birmingham Department of Cell Developmental and Integrative Biology, Birmingham, Alabama, United States
  • Chweih, Hanan, The University of Alabama at Birmingham Department of Cell Developmental and Integrative Biology, Birmingham, Alabama, United States
  • Haycraft, Courtney J., The University of Alabama at Birmingham Department of Cell Developmental and Integrative Biology, Birmingham, Alabama, United States
  • Li, Zhang, The University of Alabama at Birmingham Department of Cell Developmental and Integrative Biology, Birmingham, Alabama, United States
  • Croyle, Mandy J., The University of Alabama at Birmingham Department of Cell Developmental and Integrative Biology, Birmingham, Alabama, United States
  • Simanyi, Kristin L., The University of Alabama at Birmingham Department of Cell Developmental and Integrative Biology, Birmingham, Alabama, United States
  • Yoder, Bradley K., The University of Alabama at Birmingham Department of Cell Developmental and Integrative Biology, Birmingham, Alabama, United States
Background

Polycystic kidney disease (PKD) is an inherited disorder where cysts develop in the kidney leading to renal failure. Cyst development results from mutations in ciliary localized proteins, PC1 and PC2 (encoded by the Pkd1 and Pkd2 genes, respectively), or due to loss of the cilium (e.g., in Ift88 mutants). It is currently unknown whether flow is disrupted prior to or after cyst initiation, or whether tubule flow is important in maintaining the cells’ differentiation state. While the function of the cilium in the kidney remains enigmatic, one proposed role is as a mechanosensor that detects changes in flow through the tubule lumen.

Methods

We propose that the loss of Pkd2 leads to changes in the nephron associated with abnormal injury responses, cyst formation, and alterations in tubule flow. In this study we evaluate tubule flow during cyst initiation and progression to determine when tubule flow is altered and whether changes in flow lead to an increase in cell injury in adult induced Pkd2 mutant mice.
Pkd2 mutant mice were induced by IP injection of tamoxifen at 8 weeks of age. Dextran absorption was analyzed by fluorescence activated cell sorting (FACS) and immunofluorescence (IF) with LTA (proximal tubules) and additional nephron segment markers.

Results

At 6- and 12-weeks following tamoxifen induction, dextran absorption was still detected in proximal tubules (presence of dextran+/LTA+ cells) of mutant mice. Additionally, we observed a decrease in LTA+ cells and an increase in dextran+/LTA- cells in Pkd2 mutants at 6 weeks post induction via FACS suggesting that at this stage flow is maintained. Decreased numbers of LTA+ cells in Pkd2 mutant samples suggest either a loss or dedifferentiation of proximal tubule cells prior to cyst formation. Visualization of dextran flow through the tubules in live samples confirmed that tubule flow is still present. We will utilize IF staining for proximal tubule (HNF4a), injured (SOX9), and proliferating (Ki67) cells to analyze changes throughout cyst development.

Conclusion

Overall, our data shows that flow through the tubules is not affected in early cystogenesis, but cellular alterations, such as loss of LTA staining occur early in Pkd2 mutant mice.

Funding

  • NIDDK Support