Kidney Week

Abstract: FR-PO756

Loss of Dicer in the Peri-Wolffian Duct Stroma Leads to Aberrant Ureteric Budding and Increased Rates of Vesicoureteral Reflux

Session Information

• Development and Organoid Models
  November 08, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Development, Stem Cells, and Regenerative Medicine

• 500 Development, Stem Cells, and Regenerative Medicine

Authors

• Anslow, Melissa J., UPMC Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States

Melissa J. Anslow,



• Bodnar, Andrew J., University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Andrew J. Bodnar,



• Sims-Lucas, Sunder, UPMC Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States

Sunder Sims-Lucas,



• Bates, Carlton M., UPMC Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States

Carlton M. Bates,



• Ho, Jacqueline, UPMC Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States

Jacqueline Ho,

Background

Vesicoureteral reflux (VUR) is associated with urinary tract infections, hypertension, and reflux nephropathy, a leading cause of pediatric end-stage renal disease. Formation of the vesicoureteral junction is determined largely by the induction site of the ureteric bud from the Wolffian duct, which depends on signals from the surrounding stroma. VUR is heritable, but no single genetic mutation causes most known cases of VUR. miRNAs are small noncoding RNAs, processed by Dicer, that regulate gene expression post-transcriptionally. We hypothesize that miRNAs are necessary for vesicoureteral junction development and prevention of VUR.

Methods

We generated a transgenic mouse model with loss of Dicer in the peri-Wolffian duct stroma (mutant=Tbx18cre; Dicer^Fl/Fl). We performed euthanized cystograms and 3D reconstructions of the ureters and bladder on mutants and controls (control=Tbx18Cre negative littermates). We performed immunostaining and 3D reconstructions at E11.5 to assess ureteric bud induction, common nephric duct apoptosis, and metanephric mesenchyme positioning.

Results

Euthanized cystograms demonstrated higher rates of VUR in the mutant mice compared to control [44% (8/18) of mutants as opposed to 4.0% (3/77) of controls (p < 0.01)] at postnatal day 0 (P0). 3D reconstructions showed lower ureteral insertions into the bladder and shorter intravesicular tunnel lengths on the side of VUR in mutants compared to control and non-refluxing mutant ureters (p < 0.05) at P0. Calbindin immunostaining revealed that the ureteric bud induction site was cranially shifted in embryonic day 11.5 (E11.5) mutants compared to controls (p < 0.05). Cleaved caspase-3 and TUNEL staining at E11.5 showed no difference in apoptosis patterns between mutant and control.

Conclusion

These data suggest a requirement for miRNAs in peri-Wolffian duct stroma for normal ureteric bud induction, subsequent ureter insertion into the bladder, and prevention of VUR. This does not appear to be due to abnormal apoptosis. Current work is evaluating the metanephric mesenchyme position. Future work will elucidate which miRNAs and mRNAs in the peri-Wolffian duct stroma are critical for normal ureteric bud induction to prevent VUR.

Funding

• Other NIH Support