Abstract: SA-PO207

KAT5-Mediated DNA Damage Repair Is Essential for the Maintenance of Podocytes

Session Information

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

Category: Glomerular

  • 1003 Glomerular: Cell Biology

Authors

  • Hishikawa, Akihito, Keio University School of Medicine, Tokyo, Japan
  • Hayashi, Kaori, Keio University School of Medicine, Tokyo, Japan
  • Monkawa, Toshiaki, Keio University School of Medicine, Tokyo, Japan
  • Itoh, Hiroshi, Keio University School of Medicine, Tokyo, Japan
Background

We have recently reported the gene-selective epigenetic control in podocytes via KLF4 (Hayashi et al, JCI 2014. KI 2015). However, the precise formation process of epigenetic changes involved in diseases states remains unclear. Here we focused on KAT5, a histone acetyltransferase which has been reported as a KLF4 interacting protein and an important factor in repairing DNA, to investigate the possible role of DNA damage repair process in formation of epigenetic changes.

Methods

Expression of KAT5 was examined in streptozotocin (STZ)-induced diabetic mice model and the effect of KAT5 gene transfer was evaluated. To analyze the physiological role of KAT5, we generated podocyte-specific KAT5 knockout (KO) mice, and investigated the epigenetic changes and DNA damage status. We performed in vitro studies using cultured human podocytes to examine the mechanism of KAT5-associated epigenetic changes.

Results

KAT5 expression was significantly decreased in isolated podocytes in STZ mice and a marker of DNA double strand breaks γH2AX was increased in glomeruli of STZ mice. Restoration of KAT5 expression in STZ mice using a hydrodynamic-based gene transfer method ameliorated albuminuria, γH2AX and nephrin expression. KAT5 KO mice developed massive proteinuria (6 week-old, WT 33±16 mg/gCr, KO 3326±1023 mg/gCr, p<0.05) with segmental glomerurosclerosis and diffuse effacement of podocyte foot process. In KO mice, nephrin expression in isolated podocytes was decreased, and WT1-positive podocyte number was reduced with an increase in TUNEL positive cells. Epigenetic changes and an increase in γH2AX expression were observed in glomeruli of KO mice. In cultured human podocytes, high-glucose treatment (30mM) induced KAT5 reduction and overexpression of KAT5 increased nephrin expression. It was revealed that overexpression of KAT5 induced a decreased methylation and a decreased binding of DNMT1 in the nephrin promoter region by methylation-specific PCR method and ChIP analysis.

Conclusion

DNA damage repair through KAT5 is essential for the maintenance of podocytes and has relation to the changes in podocyte epigenome. Increased KAT5 in podocytes ameliorates diabetic nephropathy with promoted DNA damage repair and elevated nephrin expression.

Funding

  • Government Support - Non-U.S.