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Abstract: FR-OR051

Genetic Inactivation of Histone H3 K79 Methyltransferase Dot1l in Aqp2+ Progenitor Cells Causes CKD by Upregulating Endothelin-1 in Mice and Humans

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

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

Histone H3 K79 methyltransferase Dot1l represses aldosterone target genes including endothelin-1 (ET1). Aqp2+ progenitor cells give rise to all known cell types in the connecting tubule and collecting duct. Here we investigate whether genetic inactivation of Dot1l in Aqp2+ progenitor cells causes chronic kidney disease (CKD) by upregulating ET1.

Methods

Dot1lf/f Aqp2Cre (Dot1lAC) and Dot1lf/f ET1f/f Aqp2Cre (DEAC) mice were generated to disrupt Dot1l with or without intact ET1 in the Aqp2+ progenitor cells, respectively. Aqp2Cre mice were used as WT control. Mice were analyzed at the ages of 12 and 24 months. Alternatively, two-month-old mice were subject to UUO and analyzed 14 days later. Various molecular, cellular and pathological methods were employed to assess the renal function and pathology. Cells with loss of dimethyl K79 (H3m2K79-) were identified and isolated from archived kidney biopsies from patients with diabetic nephropathy (n=50) by laser capture to identify hDOT1L mutations via sequencing.

Results

At both ages, WT mice were apparently normal. Dot1lAC developed slight and severe symptoms mimicking human chronic kidney disease (CKD). The CKD symptoms include extreme polyuria, proteinuria, natriuresis, a variety of tubular abnormalities, interstitial fibrosis, and mononuclear cell infiltrate. These changes were coupled with upregulated ET1 and fibrotic markers (FSP1, Collagen IV, Vimentin, and a-SMA). However, all of these phenotypic features were ameliorated by inactivation of ET1 in DEAC mice. Consistently, Dot1lAC vs. WT developed more prominent UUO-induced kidney fibrosis, which was partially rescued in DEAC mice. Some CNT/CD cells in DN were H3m2K79-. Analysis of the microdissected H3m2K79- cells revealed two single-base deletions and an E129K mutation that is predicted to abolish the methyltransferase activity.

Conclusion

Dot1l is a new potential renoprotective factor by repressing ET1 in both mice and humans. Inactivation of Dot1l in Aqp2+ progenitor cells is sufficient to trigger CKD development.

Funding

  • NIDDK Support