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Abstract: PO0622

Evidence for Convergence of NF-κB and Growth Hormone (GH) Signaling on Stem Cell Activation in the Adult Zebrafish Kidney

Session Information

Category: Development, Stem Cells, and Regenerative Medicine

  • 500 Development, Stem Cells, and Regenerative Medicine

Authors

  • Schenk, Heiko Joachim, Mount Desert Island Biological Laboratory, Salsbury Cove, Maine, United States
  • Kamei, Caramai Nanae, Mount Desert Island Biological Laboratory, Salsbury Cove, Maine, United States
  • Wolf, Amber M., Mount Desert Island Biological Laboratory, Salsbury Cove, Maine, United States
  • Hughes, Samuel M., Mount Desert Island Biological Laboratory, Salsbury Cove, Maine, United States
  • Drummond, Iain A., Mount Desert Island Biological Laboratory, Salsbury Cove, Maine, United States
Background

Adult progenitor cells in the mesonephric kidneys are required both during neo-nephrogenesis replacing injured tubules but also during overall growth. Single-cell RNA transcriptomes of adult kidney progenitor cells point to at least two receptor systems that may initiate stem cell-based nephrogenesis: growth hormone (GH) and interleukin receptors. Here we present evidence for both injury (NF-κB activation) and growth-related pathways (GH) in stimulating stem cell-based nephrogenesis.

Methods

Adult zebrafish kidneys were injured by gentamicin i.p. injection. NF-κB signaling was determined four days post injury (dpi) by NF-κB:GFP detection of the NF-kB reporter line Tg(NF-κB:EGFP) and NF-kB-associated gene expression using qRTPCR. Requirement of NF-κB signaling during regeneration was evaluated by pharmacological NF-κB inhibition. GH signaling was evaluated after either GH or gentamicin injection by quantification of progenitor marker lhx1a:GFP in Tg(lhx1a:GFP) and stem cell marker expression by qRTPCR. Inhibitors of GH downstream signaling were used to determine GH signaling impact after kidney injury. Bulk RNAseq from positive selected GFP+ and mcherry+ single cells by FACS was performed from kidneys 7 dpi by gentamicin injection using Tg(lhx1a:EGFP;cdh17:mCherry) fish.

Results

Gentamicin-induced kidney injury leads to an increase in tubular NF-κB nuclear translocation at 4 dpi and is associated with an upregulation of NF-κB downstream target gene expression detected by qRTPCR. Gentamicin also causes GH receptors mRNA upregulation at 7 dpi along with the kidney progenitor markers osr1 and eya4. GH injection induced the formation of new nephrons as marked by Tg(lhx1a:GFP) expression in new nephron aggregates.

Conclusion

Multiple pathways may converge on adult kidney stem cells to activate new nephron formation. Growth and growth hormone may induce new nephron formation in response to increased body mass and need for osmoregulation. Kidney injury and nephron replacement correlate with nuclear translocation of NF-κB in injured tubules, suggesting the possibility of cytokine-mediated nephrogenesis in response to injury.

Funding

  • NIDDK Support