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Kidney Week

Abstract: FR-OR044

Tubule Interconnection After Zebrafish Kidney Injury

Session Information

  • Development and Stem Cells
    November 08, 2019 | Location: 152, Walter E. Washington Convention Center
    Abstract Time: 05:06 PM - 05:18 PM

Category: Development, Stem Cells, and Regenerative Medicine

  • 500 Development, Stem Cells, and Regenerative Medicine

Authors

  • Kamei, Caramai Nanae, Massachusetts General Hospital, Charlestown, Massachusetts, United States
  • Drummond, Iain A., Massachusetts General Hospital, Charlestown, Massachusetts, United States
Background

Nephrons made during kidney development and newly made during zebrafish kidney regeneration must establish tubule lumen interconnections with the collecting system. The zebrafish adult kidney regenerates after gentamicin injury from an adult progenitor cell population, forming 20-100 new nephrons that subsequently invade and "plumb into" the pre-existing collecting system and restore renal function. Using the zebrafish adult kidney as a model of synchronous nephron-collecting duct fusion, we investigated the role of growth factor signaling pathways in this process.

Methods

Tg(TCFLef-miniP:dGFP) Wnt reporter expression was used to reveal high Wnt signaling domains in new nephrons. The Wnt inhibitors IWR1 and IWP2 were applied to injured adult zebrafish to test requirements for Wnt signaling. Homozygous adult Crispr/Cas9 indel mutants in fzd9b and wnt9b were generated.

Results

We find that new nephron aggregates are patterned by canonical Wnt signaling. High canonical Wnt signaling cells formed a single cell thick dome within cell aggregates and polarized to form rosettes with an apical constriction predicting the site of future tubule lumen. Cells at the distal end of the new nephron extend invasive processes or invadopodia into the underlying tubular epithelium. Short term inhibition of Wnt signaling using the chemical inhibitors IWR1 and IWP2 inhibited invadopodia formation and blocked tubule interconnection events. Adult homozygous fzd9b mutants exhibit ectopic distal cell proliferation and a failure of convergent extension in new nephrons after injury while wnt9b mutants produce fewer new nephrogenic aggregates. A quantitative RT-PCR screen of candidate genes highly upregulated in both zebrafish nephron progenitors after injury and human cancer metastasis implicates new pathways involved in the invasion process.

Conclusion

Wnt signaling is required for tubule invasion and correlates with expression of multiple genes associated with metastatic cell invasiveness. Manipulation of Wnt signaling is an opportunity to engineer kidney tubule interconnections.

Funding

  • NIDDK Support