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Abstract: TH-OR016

A Functional Genomic Screen Identifies a CDKL5-SOX9 Regulatory Axis in Epithelial Cell Death and Kidney Injury

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Kim, Ji Young, The Ohio State University, Columbus, Ohio, United States
  • Bai, Yuntao, The Ohio State University, Columbus, Ohio, United States
  • Jayne, Laura A., The Ohio State University, Columbus, Ohio, United States
  • Pabla, Navjotsingh P., The Ohio State University, Columbus, Ohio, United States
Background

Numerous clinical conditions are associated with inflammatory, toxic, and hypoxic insults to tubular epithelial cells. The resulting epithelial cell dysfunction and cell-death are the hallmarks and underlying cause of acute kidney injury (AKI), a common disorder that predominantly develops in hospitalized patients. Importantly, the patients that recover from an episode of AKI are at increased risk of developing chronic kidney disease, end-stage renal disease and cardiovascular dysfunction- disorders that are associated with significant morbidity and mortality. To identify novel regulators of renal epithelial cell death and AKI, here, we have used a kinome-wide functional genomic screening to identify protein kinases that contribute to the pathogenesis of AKI.

Methods

An unbiased kinome-wide siRNA screen for regulators of renal epithelial cells was carried out in a murine epithelial cell line. Through subsequent in vivo validation experiments, we identified cyclin-dependent kinase-like 5 (CDKL5) also known as serine/threonine kinase 9 (STK9) as a key regulator of renal cell-death and injury. To directly define the role of CDKL5 in vivo, kidney tubule specific CDKL5 knockout mice were generated. In addition, a pharmacological inhibitor of CDKL5 kinase was evaluated in cisplatin nephrotoxicity and ischemia-associated AKI. Later proteomic studies were carried out to identify the transcription factor Sox9 as a bona fide Cdkl5 substrate and a key downstream target in renal epithelial cells.

Results

High-throughput siRNA screening and validation studies identified CDKL5 kinase as a crucial, previously unknown regulator of renal epithelial cell-death. In vivo studies showed that genetic or pharmacological ablation of CDKL5 function provides mitigates AKI in both cisplatin and ischemia-associated kidney injury. We also found that Sox9 is phosphorylated on the Ser-199 residue by Cdkl5 during kidney injury in vivo. Cdkl5-mediated phosphorylation reduced the stability of Sox9 protein.

Conclusion

Here we have found that Cdkl5 also known as Stk9 is a stress responsive kinase that controls epithelial cell fate during AKI. We propose that Cdkl5 activation promotes renal dysfunction through phosphorylation-mediated destabilization of pro-survival transcription factor Sox9.

Funding

  • Private Foundation Support