Kidney Week

Abstract: TH-OR29

A Novel Model of Hyperuricemia via Inducible Uricase Knock-Out

Session Information

• Fluid, Electrolyte, and Acid-Base Disorders: Basic and Clinical Research
  November 04, 2021 | Location: Simulive, Virtual Only
  Abstract Time: 04:30 PM - 06:00 PM

Category: Fluid, Electrolyte, and Acid-Base Disorders

• 901 Fluid, Electrolyte, and Acid-Base Disorders: Basic

Authors

• Halperin Kuhns, Victoria L., University of Maryland School of Medicine, Baltimore, Maryland, United States

Victoria L. Halperin Kuhns, PhD

• Lane-Harris, Allison C., University of Maryland School of Medicine, Baltimore, Maryland, United States

Allison C. Lane-Harris,

• Woodward, Owen M., University of Maryland School of Medicine, Baltimore, Maryland, United States

Owen M. Woodward,

Background

Hyperuricemia contributes to the development of kidney stones, chronic kidney disease, cardiovascular disease, metabolic syndrome, and gout. Classically, hyperuricemia was viewed as caused by an overproduction of urate (UA), underexcretion, or a combination of the two. Creating genetic animal models for overproduction type hyperuricemia is complicated because, unlike humans, mice express the enzyme uricase (Uox), which metabolizes UA. Previous models using germline Uox knock out resulted in significant juvenile mortality related to crystal induced nephropathy making longitudinal and transcriptional investigations difficult. Here we describe a novel inducible model of Uox inactivation (UOX-iKO) that surmounts previous challenges to begin to elucidate renal consequences of overproduction type hyperuricemia.

Methods

CRISPR-Cas9 was used to insert LoxP sites into the Uox gene of C57BL6J mice, then crossed with mice harboring a tamoxifen inducible Cre (Gt(ROSA)26Sor^{tm1(cre/ERT2)Tyj)}). Male (M) and female (F) mice were induced at 9 weeks with tamoxifen or vehicle control and sacrificed after 2 weeks or followed longitudinally. RNA-Seq was performed on kidneys of 2 week induced and control mice, followed by DESeq2 and pathway analysis.

Results

Induced animals of both sexes showed significant increases in serum UA and urinary UA excretion 2 weeks after induction, increases that persisted for 10 weeks with no increase in mortality. RNA-Seq analysis revealed both sexes showed differential expression of inflammatory and other immune associated genes including renal injury markers Lcn2 and Stc1, indicating subtle acute renal injury, even without changes in BUN. M mice demonstrated significant decreases in expression of UA transporter genes Slc17a1 and Slc17a3, while F mice showed a significant increase in UA associated transcription factor Hnf4a. M but not F mice also had differential expression of genes involved in metabolic processes, while F but not M mice showed differential expression in signal transduction pathways including phospholipase C and toll-like receptor signaling.

Conclusion

The UOX-iKO mice cannot metabolize UA, and thus are an excellent model for overproduction of UA. These mice provide significant insights into the acute transcriptional changes occurring after UA increases, mechanisms of renal UA homeostasis in vivo, and new insights into hyperuricemia treatment.

Funding

• NIDDK Support