Kidney Week

Abstract: FR-PO0172

Proximal Tubule-Specific Knockout of Ferroportin in Diabetic db/db Mice: A Novel Model for Renal Iron Dysregulation in Diabetic Kidney Disease

Session Information

• Diabetic Kidney Disease: Metabolic, Mitochondrial, and Inflammatory Mechanisms
  October 23, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Cardiovascular-Kidney-Metabolic Health

• 601 Cardiovascular-Kidney-Metabolic Health: Basic

Authors

• Thompson, Austin Dennis, University of Michigan Michigan Medicine, Ann Arbor, Michigan, United States

Austin Dennis Thompson, PhD

• Soofi, Abdul A., University of Michigan Michigan Medicine, Ann Arbor, Michigan, United States

Abdul A. Soofi, PhD

• Qamhieh, Ibrahim, University of Michigan Michigan Medicine, Ann Arbor, Michigan, United States

Ibrahim Qamhieh

• Pennathur, Subramaniam, University of Michigan Michigan Medicine, Ann Arbor, Michigan, United States

Subramaniam Pennathur, MD

Background

Diabetic Kidney Disease (DKD) affects 1/3 of patients with diabetes and is the leading cause of end-stage renal disease, accounting for up to 50% of incident renal replacement therapy cases. While persistent disruption of iron homeostasis is a well-established modulator of maladaptive tubular repair & tissue injury in DKD progression, local proximal tubule (PT) iron dysregulation in the context of DKD outcomes remains understudied. We thus generated a novel PT-specific knockout of Ferroportin (FPN), the only known mammalian iron exporter, on the well described diabetic (typeII) db/db mice background.

Methods

db/db FPN conditional knockout mice (db/db, SLC40A1^fl/fl, Phosphoenolpyruvate Carboxykinase-Cre, mT/mG reporter; DFPN-ptKO) were generated with PT-specific Cre recombination validated by eGFP reporter immunofluorescence (IF) & PCR. Renal FPN distribution was examined by IF, and tubular injury was assessed by KIM1. Body weight, blood glucose, and proteinuria were evaluated over 16wks to assess diabetic phenotype retention in DFPN-ptKO mice. PT iron was assessed histologically via Prussian Blue staining. Pan14-3-3 was evaluated in urine as a DKD progression marker. Ferroptosis markers including GPX4, ACSL4, 4HNE, and TfR1 R3-dimers were evaluated.

Results

PT-specific Cre recombination & db/db leptin receptor mutation (T/T) in DFPN-ptKO mice were confirmed by eGFP reporter expression in PTs, tomato-red expression in non-PT cells, and PCR, respectively. FPN deletion in PTs was validated by IF. By 8w DFPN-ptKO mice exhibited a canonical db/db phenotype evident by a ≥1.5-fold increase in body weight, >250mg/dl blood glucose, and proteinuria, compared to db/+ controls. At 16w, DFPN-ptKO mice had marked iron accumulation in PTs, confirmed by histological Prussian Blue Stain, compared to db/+ & db/db controls; they exhibited increased KIM1 & ferroptotic signatures (i.e., decreased GPX4, elevated ACSL4, 4HNE, & TfR1 R3-dimers). Urinary analyses of DFPN-ptKO mice (8w-16w) confirmed marked proteinurea & Pan14-3-3 vessicle excretion, compared to db/+ controls.

Conclusion

Here, we characterize the generation of a novel diabetic (typeII) db/db conditional knockout mouse with proximal tubule-specific deletion of Ferroportin to aid future studies in mechanistically deciphering how local proximal tubule iron dysregulation affects DKD progression and outcomes.

Funding

• NIDDK Support