Abstract: FR-PO254

A New Inducible Aqp2ECE System Reveals the Self-Renewal and Multipotentiality of Aqp2+ Progenitor Cells in Adult Mouse Kidneys

Session Information

  • Stem Cells
    November 03, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Developmental Biology and Inherited Kidney Diseases

  • 402 Stem Cells

Authors

  • Chen, Lihe, NIH, Bethesda, Maryland, United States
  • Zhang, Ye, Albany Medical College, Albany, New York, United States
  • Gao, Chao, Albany Medical College, Albany, New York, United States
  • Zhang, Long, Albany Medical College, Albany, New York, United States
  • Chen, Enuo, Albany Medical College, Albany, New York, United States
  • Zhang, Wenzheng, Albany Medical College, Albany, New York, United States
Background

Stem cells are defined by unlimited self-renewal capacity and pluripotentiality. Progenitor cells have pluripotentiality, but no or limited self-renewal potential. Using Aqp2Cre driver, we previously showed that embryonic Aqp2+ progenitor cells generate all known cell types in the connecting tubule/collecting duct. However, the constitutive Aqp2Cre driver cannot be used to assess adult Aqp2+ progenitor cells.

Methods

Here, we report a new inducible Aqp2ECE knock-in mouse model, which allows us to demonstrate the self-renewal and multipotentiality of Aqp2+ progenitor cells in adult kidneys. Aqp2ECE was created by inserting a cassette expressing a specific Cre fusion at the ATG of the endogenous Aqp2 locus and used to generate Aqp2ECE Rainbow mice.

Results

Without Tamoxifen induction, no fluorescence proteins were detectable at P1, P23, and P42. In kidneys induced with Tamoxifen (4 mg/20g BW) at P42 and examined at P63, seldom and isolated individual cells expressing one of 4 fluorescence proteins (XFP+, where X=G, R, C, or Y) were observed. Double and triple immunofluorescence (IF) staining revealed that all RFP+ and GFP+ cells were also Aqp2+, with none of them having detectable expression of V-ATPase B1B2. In mice induced with Tamoxifen at P23 and P69, treated with dietary LiCl (40 mmol lithium/kg food) at P95 for 18 days, and examined at P113, there were clones of 2-5 cells expressing the same fluorescence protein without interruption by any single cell of another color. While the majority of the GFP+ and RFP+ cells remained Aqp2+, some of them lost Aqp2 expression and gained expression of V-ATPase B1B2, AE1 or Pendrin, indicating conversion of “principal” cells to intercalated cells. Some GFP+ and RFP+ cells displayed an intermediate state and characterized by being positive for both a principal (Aqp2+) and an intercalated cell marker (V-ATPase B1B2, AE1, or Pendrin).

Conclusion

We conclude that 1) Aqp2ECE has 0% leakiness (100% dependence of Cre recombinase activity on Tamoxifen), noticeable inducibility, and 100% fidelity in recapitulating the endogenous Aqp2 expression; 2) Rare Aqp2+ progenitor cells exist in adult mouse kidney, possess self-renewal and multipotentiality, and function in kidney maintenance and lithium-induced remodeling. Long-term chasing is underway to confirm and extend these findings.

Funding

  • NIDDK Support