Abstract: SA-PO537

DNMT1-Dependent Cytosine Methylation Is Essential for the Control of Progenitor Cell Differentiation in Early Nephron Development

Session Information

  • Developmental Biology
    November 04, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Developmental Biology and Inherited Kidney Diseases

  • 401 Developmental Biology

Authors

  • Li, Szu-Yuan, University of Pennsylvania, Philadelphia, United States
  • Park, Jihwan, University of Pennsylvania, Philadelphia, Pennsylvania, United States
  • Shrestha, Rojesh, University of Pennsylvania, Philadelphia, Pennsylvania, United States
  • Susztak, Katalin, University of Pennsylvania, Philadelphia, Pennsylvania, United States
Background

The basic functional units of the mammalian kidney, nephrons, are generated repetitively during kidney organogenesis. Six2 positive cells represent a multipotent nephron progenitor population within cap mesenchyme and give rise to all epithelial cells in the kidney. Cytosine methylation changes play a key role in gene expression regulation; however, the role of cytosine methylation changes in kidney development has not been studied. Cytosine methylations are established by DNA methyltransferases (Dnmt) and are further modified by Tet eleven hydroxylase (TETs). Dnmts function as methylation writers and maintainers, and Tets act as methylation erasers.

Methods

To examine the role of cytosine methylation in renal epithelial cells, we crossed mice with DNMT1, 3a, 3b, Tet1 or Tet2 conditional allele (flox) with Six2cre mice. To understand the role of cytosine methylation in differentiated epithelial cells, we crossed Dnmt1,3a,3b and Tet1,2 mice with podocin Cre mice. Genome wide transcript level and cytosine methylation changes were analyzed by RNA sequencing and reduced representation bisulfate sequencing (RRBS).

Results

DNMT1, 3a, 3b and Tet1 are highly expressed in embryonic kidneys, and their expression levels decrease remarkably after kidney organogenesis is completed. Mice with podocyte-specific ablation of Dnmt1, 3a, 3b, Tet1 or Tet2 did not show functional or structural changes. We have induced glomerular disease in these animals by Adriamycin injection and found no differences in injury response when compared to controls, indicating the dispensable role for these enzymes. On the contrary, Six2 cre DNMT1 f/f mice died on day1 after birth; their kidneys were small and their bladders void of urine. Histological analysis revealed that although the progenitor cell population was maintained in absence of DNMT1, nephron maturation stopped in early stages (renal vesicle/ C-shape body). Expression of the cap mesenchymal genes including Gdnf were increased while nephron maturation genes including Fgf8 and Lhx1 were decreased.

Conclusion

DNMTs and TETs expression are dynamic during kidney development. Dnmt1 dependent DNA methylation is essential to complete nephron maturation.

Funding

  • NIDDK Support