Abstract: TH-PO320

Tubule Interconnection after Zebrafish Kidney Injury

Session Information

Category: Acute Kidney Injury

  • 002 AKI: Repair and Regeneration

Authors

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

Cell-based therapies for kidney regeneration propose the use of renal epithelial or progenitor cells to generate new nephrons and replace damaged nephrons in injured kidneys. For cell-based approaches to fulfill their promise, newly made nephrons must establish tubule lumen interconnections with the collecting system.

Methods

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" to 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.

Results

Tg(TCFLef-miniP:dGFP) Wnt reporter expression revealed 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 formation. Cells under the dome exhibiting low levels of canonical Wnt signaling and low proliferation appear to invade the tubular epithelium, while cells corresponding to the dome flatten into a segment of the forming new nephron and continue to maintain high levels of canonical Wnt signaling activity and proliferation until lumen formation. Tg(lhx1a:GFP) reporter expression is maintained at high levels in the entire distal end of the new nephron, allowing visualization of the invasion process. 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. Newly generated kidney cell-type specific transgenics will allow spatially and temporally controlled modulation of Wnt signaling to identify the cells responsible for generating and interpreting tubule interconnection signals.

Conclusion

Canonical Wnt signaling is required for tubule interconnection during adult zebrafish kidney regeneration.

Funding

  • NIDDK Support