Abstract: TH-PO335

Inhibition of the Transcriptional Activator Etv4 in Proximal Tubule Cells Protects Kidneys from Tubular Injury

Session Information

Category: Acute Kidney Injury

  • 002 AKI: Repair and Regeneration

Authors

  • Fleig, Susanne V., Hannover Medical School, Hannover, Germany
  • Machado, Flavia G., Washington University in St Louis, School of Medicine, St Louis, Missouri, United States
  • Chang Panesso, Monica, Washington University in St. Louis, St Louis, Missouri, United States
  • Wu, Chia-Chun, Chi Mei Medical Center, Tainan, Taiwan
  • Uchimura, Kohei, Washington University in St. Louis, St Louis, Missouri, United States
  • Kramann, Rafael, RWTH Aachen University, Lemiers, Netherlands
  • Yanagita, Motoko, Kyoto University Graduate School of Medicine, Kyoto, Japan
  • Humphreys, Benjamin D., Washington University School of Medicine, Clayton, Missouri, United States
Background

The transcription factor Etv4 regulates developmental programs in several organs including kidney, but roles for Etv4 in kidney injury are poorly defined. Here we have investigated the expression, function and regulation of Etv4 during dedifferentiation and repair after AKI.

Methods

We generated a novel mouse model with inducible expression of a dominant-negative Etv4 (DN-Etv4) in proximal tubule cells. NDRG1CreERT2; R26-DN-Etv4 bigenic mice were subject to moderate and severe bilateral IRI and tissue histology, gene expression and kidney function was monitored. Primary human proximal tubule cultures (RPTEC) and iPS-derived kidney organoids were used to assess regulation of Etv4 expression.

Results

At 24h after IR injury, mice with proximal specific DN-Etv4 expression had a significantly lower increase in creatinine and BUN than controls; a functional difference is not seen at 3 and 5 days past injury. DN-Etv4 expressing mice have a much lower tubular injury score at 24h than controls. Caspase 3 staining shows a significantly lower amount of apoptotic cells at 24h. The metabolic intermediate α-ketoglutarate (aKG) is upregulated in ischemia due to lack of decarboxylation via PHD2 (Olenchock BA et al, Cell 2016). aKG inversely controls etv4 expression in cancer, and high etv4 was linked to hypoxia-induced apoptosis (Keenan M. et al, PLoS Genetics 2015); we observed strong downregulation of Etv4 expression in human RPTECs after exposure to aKG. Finally, gentamicin treatment of human iPS-derived kidney organoids potently induced Etv4 mRNA.

Conclusion

The transcriptional activator etv4 is induced in dedifferentiatied proximal tubule after AKI. Our results suggest that it normally acts to induce apoptosis in the hypoxic postischemic tubule, as blocking its function improved cell survival, tubular injury scores and BUN after IRI. This pathway is conserved in humans, since gentamicin induced Etv4 mRNA in human iPS-derived kidney organoids. Finally, aKG downregulated Etv4 expression in vitro, suggesting a novel therapeutic strategy.

Funding

  • NIDDK Support