Abstract: TH-PO0555
Multiple Wnt Signaling Pathways Direct Epithelial Tubule Interconnection in Regenerating Zebrafish Kidneys
Session Information
- Development, Stem Cells, and Regenerative Medicine
November 06, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Development, Stem Cells, and Regenerative Medicine
- 600 Development, Stem Cells, and Regenerative Medicine
Authors
- Drummond, Iain A., Mount Desert Island Biological Laboratory, Bar Harbor, Maine, United States
- Kamei, Caramai Nanae, Mount Desert Island Biological Laboratory, Bar Harbor, Maine, United States
- Sampson, William, Mount Desert Island Biological Laboratory, Bar Harbor, Maine, United States
- Hughes, Samuel M., Mount Desert Island Biological Laboratory, Bar Harbor, Maine, United States
- Schenk, Heiko Joachim, Mount Desert Island Biological Laboratory, Bar Harbor, Maine, United States
- McCracken, Kyle, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
- Marciano, Denise K., The University of Texas Southwestern Medical Center, Dallas, Texas, United States
- Oxburgh, Leif, Rogosin Institute, New York, New York, United States
Background
Epithelial tubule fusion is fundamental for kidney morphogenesis. Differentiating nephron tubules interconnect with collecting system epithelia to generate a lumenal pathway for fluid excretion. In the adult zebrafish kidney, nephrogenesis and nephron fusion occurs as a regenerative response to injury and provides a model to explore cell signaling pathways required for tubule interconnection.
Methods
Adult fish experiments were performed with age-matched siblings between 6-18 months of age. Acute kidney injury was induced by intraperitoneal injection of gentamicin. Drug treatments were performed with drugs in system water starting at 7 days post injury (dpi) until harvesting kidneys at 8dpi. Gene and protein expression were visualized by in situ hybridization or immunofluorescence and imaged by confocal microscopy. Image quantification was performed using BitPlane Imaris or ImageJ software.
Results
Canonical Wnt signaling induces a mesenchymal, invasive cell phenotype that is required, along with Src kinase and rac1, to generate new nephron invasive basal cell protrusions. Mutation in wnt4 or treatment with the canonical Wnt inhibitor IWR1 blocked formation of basal protrusions in forming nephrons. Mutation in the Wnt receptor frizzled9b revealed a fusion-associated non-canonical Wnt pathway that limits canonical Wnt signaling and drives Rho kinase-dependent cell shape changes and orientation of invasive basal protrusions. Wnt and frizzled9b mutants fail to interconnect new nephrons with target distal tubules.
Conclusion
A complex interplay of canonical and non-canonical Wnt signaling systems mediate the formation of patent, orthogonal tubule interconnections and ensure fluid flow in newly engrafted kidney nephrons. Canonical and non-canonical Wnt signaling pathways operate simultaneously in the same cells to orient and drive invasive cell behavior and permit cell shape changes that facilitate tubule interconnection. Our findings may have practical implications for utilizing stem cell-derived kidney organoid nephrons in tissue replacement and kidney augmentation therapies by providing new knowledge of cellular signaling systems that promote tubule interconnection and function of engrafted nephrons.
Funding
- NIDDK Support