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Abstract: SA-PO085

Tnik, a Novel Pro-Repair Kinase That Promotes Renal Cell Differentiation After Injury

Session Information

  • AKI: Mechanisms - III
    November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Bradford, Shayna T. J., Washington University in St Louis School of Medicine, St Louis, Missouri, United States
  • Kirita, Yuhei, Washington University in St Louis School of Medicine, St Louis, Missouri, United States
  • Wu, Haojia, Washington University in St Louis School of Medicine, St Louis, Missouri, United States
  • Muto, Yoshiharu, Washington University in St Louis School of Medicine, St Louis, Missouri, United States
  • Humphreys, Benjamin D., Washington University in St Louis School of Medicine, St Louis, Missouri, United States

Group or Team Name

  • Humphreys Lab
Background

Following acute kidney injury (AKI), epithelial cells lining proximal tubules of the nephron repopulate injured tubules to support repair. However, a portion of cells fail to undergo repair and are characterized by increased expression of proinflammatory/profibrotic molecules as well as decreased expression of markers of terminal differentiation. The molecular pathways driving the generation of failed-repair proximal tubule cells are undefined. However, we hypothesize that these cells cause local tissue inflammation and fibrosis, promoting the AKI to chronic kidney disease transition.

Methods

Using snRNA-seq, we identified a Traf2 and Nck Interacting Kinase, Tnik, to be exclusively expressed in failed-repair proximal tubule cells post AKI (2 and 6 weeks) in mice. Like failed-repair proximal tubule cells, primary human renal proximal tubule epithelial cells (hRPTECs) adopt an injury phenotype when cultured on plastic and can be used to model failed-repair proximal tubule cells. Therefore, we subjected primary-hRPTECs to 72 hours of Tnik silencing using pooled siRNA against human Tnik. We confirmed Tnik suppression by immunoblotting and proceeded with RNA-seq analysis to assess the transcriptome of Tnik depleted primary-hRPTECs (n = 6).

Results

508 genes were upregulated, and 685 genes were downregulated in response to Tnik depletion (log2 fold change > 1). Pathway analysis revealed upregulation of Type I Interferon signaling, while organic acid transport pathways were downregulated. By qPCR and immunoblotting, we validated increased levels of inflammatory and injury genes (CCL2, AXIN2), along with decreased levels of organic acid transport and differentiation genes (SLC3A1, HFN4a) found in our RNA-seq dataset.

Conclusion

Since Tnik depletion increases inflammatory signals and decreases renal cell differentiation markers, we conclude that Tnik is a novel proximal tubule pro-repair kinase that functions to reduce inflammation and shift cells toward differentiation and repair following injury. Data from these studies may serve as the basis for novel therapeutics that enhance proximal tubule Tnik activity, thereby improving AKI outcomes.

Funding

  • NIDDK Support