Kidney Week

Abstract: FR-PO1197

Aqp2+ Progenitor Cells Link Distal Renal Segments to Kidney Fibrosis via a Novel Profibrotic Pathway

Session Information

• CKD: Mechanisms, AKI, and Beyond - 2
  November 07, 2025 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

• 2303 CKD (Non-Dialysis): Mechanisms

Authors

• Tsilosani, Akaki, Albany Medical College, Albany, New York, United States

Akaki Tsilosani, PhD

• Mulroy, Evelyn Ruth, Albany Medical College, Albany, New York, United States

Evelyn Ruth Mulroy

• Chen, Enuo, Albany Medical College, Albany, New York, United States

Enuo Chen

• Das, Shreya, Albany Medical College, Albany, New York, United States

Shreya Das, PhD

• Sun, Wei, Albany Medical College, Albany, New York, United States

Wei Sun, PhD

• Zhang, Wenzheng, Albany Medical College, Albany, New York, United States

Wenzheng Zhang, PhD

Background

Aqp2⁺ progenitor cells (AP) generate distal renal segments including the late distal convoluted tubule (DCT2), connecting tubule (CNT), and collecting duct (CD). Deletion of histone H3 K79 methyltransferase Dot1l in AP in Dot1l^f/f Aqp2Cre (Dot1l^AC) mice facilitates kidney fibrosis during aging by upregulating Endothelin 1 (ET1) through histone deacetylase 2 (HDAC2). Whether neutrophil gelatinase-associated lipocalin (NGAL) functions in this process is unknown. We hypothesize that NGAL is repressed by Dot1l and promotes kidney fibrosis via ET1.

Methods

IMCD3 cells and five groups of 14-month-old mice (WT, Dot1l^AC, Dot1l^f/f Edn1^f/f Aqp2Cre (DE^AC), NGAL^-/-, and Dot1l^f/f Aqp2Cre NGAL^-/- (DL^-/-)) were used. Techniques included RT-qPCR, immunofluorescence, in-situ hybridization, confocal microscopy, gene silencing, iron assays, and unilateral ureteral obstruction (UUO).

Results

In Dot1l^AC mice, NGAL mRNA was only expressed in Dot1l-deleted DCT2/CNT/CD. Silencing Dot1l in IMCD3 cells increased NGAL. DL^-/- vs. Dot1l^AC mice had less HDAC2, ET1, and kidney fibrosis. DE^AC vs. Dot1l^AC mice had comparably high NGAL, but significantly reduced ET1 and fibrosis. NGAL colocalized with its receptor 24p3R in vivo and in vitro, and knockdown of 24p3R abrogated NGAL endocytosis. Treating IMCD3 cells with NGAL increased intracellular iron, HDAC2 and ET1. Iron overloading of IMCD3 cells similarly increased HDAC2 and ET1. Point mutations in NGAL’s putative iron-binding domains abolished iron trafficking. In UUO mice, NGAL expression in DCT2/CNT/CD preceded fibrotic markers; NGAL ablation reduced post-UUO fibrosis

Conclusion

Dot1l depletion in AP-derived DCT2/CNT/CD upregulates NGAL, which promotes ET1 via HDAC2. ET1 fascilitates kidney fibrosis. NGAL may directly bind and import iron through 24p3R-mediated endocytosis to regulate HDAC2 and ET1. Our findings define a novel Dot1l–NGAL–24p3R–iron–HDAC2–ET1 pro-fibrotic pathway linking progenitor identity to fibrosis.

Funding

• Other NIH Support

Digital Object Identifier (DOI)

• doi: 10.1681/ASN.202506bec3bh