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Kidney Week

Abstract: PO0594

Pyruvate Kinase M2 in Renal Tubular Cells Is a Key Regulator of Kidney Repair After Ischemic Injury

Session Information

  • CKD Mechanisms - 1
    October 22, 2020 | Location: On-Demand
    Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

  • 2103 CKD (Non-Dialysis): Mechanisms

Authors

  • Wei, Qingqing, Augusta University, Augusta, Georgia, United States
  • Dong, Zheng, Augusta University, Augusta, Georgia, United States
Background

Tissue injury and repair is associated with changes of metabolism. In kidneys, metabolic changes including mitochondrial dysfunction and induction of glycolysis have been reported in renal fibrosis and chronic kidney disease. It remains unclear whether and how the metabolic changes contribute to kidney injury and repair. We have examined the effects of glycolysis inhibitors and the ablation of pyruvate kinase M2 (PKM2, an enzyme in glycolysis) in kidney tubules. Glycolysis inhibitors (including PKM2 inhibitor shikonin) suppressed renal fibrosis in the mouse model of unilateral ureter obstruction (UUO). Interestingly, in vitro the inhibitors suppressed fibrotic gene expression (e.g. fibronectin and a-SMA) in fibroblasts, but not in cultured renal tubular cells.

Methods

To further understand the role of glycolysis in renal tubular cells in vivo, we established a mouse model in which PKM2 ablation in renal tubule cells can be induced by doxycycline. To this end, PKM2-floxed mice were bred with Pax8-rtTA/LC1 CRE recombinase mice to create an inducible renal tubule-specific PKM2 knockout (iRT-PKM2-KO) mouse model. Exposure to doxycycline for 5-7 days induced PKM2 ablation in all renal tubules in iRT-PKM2-KO mice, but not in wild-type littermates. These mice were subjected to 30 minutes of unilateral renal ischemia-reperfusion one day after initial doxycycline treatment, and kidneys were collected at 2 weeks later for histology, immunoblot analysis, and fibrosis staining.

Results

Wild-type mice showed increased expression of collagen I, collagen IV, vimentin and a-SMA in kidney tissues. The increase of collagen I was significantly attenuated in iRT-PKM2-KO mice, while collagen IV and vimentin induction was marginally inhibited and no inhibition for fibronectin and a-SMA in these mice. Wild-type and iRT-PKM2-KO kidney tissues had similar levels of Sirius red staining of collagen fibrils. We further examined Lotus Tetragonolobus lectin (LTL) staining of proximal tubules, which detected obviously more intact proximal tubules in iRT-PKM2-KO mice than in wild-type littermates.

Conclusion

Together, these results indicate a pathogenic role of glycolysis in maladaptive kidney repair. Importantly, PKM2 and associated metabolism contribute to the degeneration of renal tubules after acute kidney injury.

Funding

  • NIDDK Support