Abstract: TH-OR014

A Snapshot of RNA Expression in a Single Segment of the Kidney Reveals Stimulus Specific Responses

Session Information

Category: Acute Kidney Injury

  • 001 AKI: Basic

Authors

  • Xu, Katherine, None, East Elmhurst, New York, United States
  • Stauber, Jacob, Columbia University, New York, New York, United States
  • Barasch, Jonathan M., Columbia Presbyterian, New York, New York, United States
Background

The identification of acute kidney disease at the time of patient encounter remains a central problem in clinical medicine. A single analyte, the serum creatinine (sCr) is currently in use as a surrogate for tubular, vascular, or interstitial cellular damage. Nonetheless the sCr test is not specific to kidney injury, but rather might reflect physiological responses to a the primary disease in a distant organ. In addition, while cellular events occur over minutes or hours, sCr requires 24 hours or more to reach a worrisome clinical threshold or demonstrate further deterioration of tissue function and architecture.

Methods

To examine the cell and stimulus specific responses, we have adapted the method of Gay et al, (2013) to allow cell specific labelling of RNA at the time of our choosing after injury. The technique involves cre driven, cell specific expression of a uracil phosphoribosyltransferase (Uprt) and the subsequent purification of 4-thio-uracil labelled nascent RNAs. We used this technique with Atp6b1v1-Cre and Hoxb7-Cre to perform transcriptional profiling of the new newly synthesized RNA in the cell types in mouse models of iAKI (intrinsic-AKI) and vAKI volume (volume depleted-AKI).

Results

We found hundreds of genes responding in each cell specific and stimulus specific RNA pool. There was almost no overlap between vAKI and iAKI, although they both raise sCr, and limited overlap between Atp6b1v1-Cre and Hoxb7-Cre RNA pools. To validate this technique, we show that collecting duct marker genes are enriched and genes from the other segments of the kidney are deenriched in the tagged RNA. In addition, we validated the technique by independently using a GFP-Hoxb7 mouse and FAC-sorting out the collecting duct cells for gene expression.

Conclusion

Hence, a snapshot of newly synthesized RNA reveals the complexity subsumed by diagnostic classifications dependent on sCr. We suggest that the Uprt technique will allow characterization of each cell type in the nephron at multiple time points after the onset of injury. These data will replace our current diagnostic strategies with Precision Medicine approach to AKI.

Funding

  • NIDDK Support