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Abstract: FR-OR09

ZFP24 Drives Sox9 Upregulation During AKI

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Kim, Ji Young, The Ohio State University, Columbus, Ohio, United States
  • Silvaroli, Josie A., The Ohio State University, Columbus, Ohio, United States
  • Pabla, Navjot Singh P., The Ohio State University, Columbus, Ohio, United States
Background

Sox9 is a member of the Sox family of transcription factors that have essential roles in cell-fate determination. In the normal adult kidneys, Sox9 expression is very low. During AKI, Sox9 is transcriptionally upregulated. Functionally, Sox9 plays a cytoprotective role during the early phase of AKI and facilitates repair during the recovery phase. Interestingly, the identify of transcription factor(s) that drive Sox9 upregulation during AKI remains unknown. Zinc finger protein ZFP24 belongs to the superfamily of SCAN-domain containing transcription factors. Outside the nervous system, ZFP24 is expressed in several tissues such as kidney, liver, heart, and spleen. However, its role in the kidney or its contribution to transcriptional regulation of Sox9 remains unknown.

Methods

To identify upstream transcriptional regulators of Sox9, we used RNAi mediated silencing of transcription factors and related genes (siRNA libraries from Dharmacon and Sigma, ~1900 genes) in BUMPT cells, followed by high-throughput-qPCR based examination of stress-induced (cisplatin) Sox9 gene induction. The primary and secondary screens in BUMPT and HK-2 cells identified ZFP24 as the key Sox9 regulatory gene. We then generated a conditional knockout mouse by crossing ZFP24 floxed mice with GGT1-Cre mice. The severity of renal injury (bilateral ischemia and cisplatin nephrotoxicity) was monitored in control and knockout littermates through measurement of blood urea nitrogen, serum creatinine, histological analysis, and biomarker analysis. To test promoter binding, we performed ZFP24 chromatin immunoprecipitation studies in renal tissues. Sox9 and its target gene upregulation was also monitored through qPCR and western blot analysis.

Results

We found that ZFP24 gene deletion in tubular epithelial cells increases the severity of ischemia and cisplatin-associated AKI. Importantly, ZFP24 gene ablation significantly suppresses injury induced Sox9 upregulation in tubular epithelial cells. Chromatin immunoprecipitation studies also demonstrated direct binding of ZFP24 to the Sox9 promoter region.

Conclusion

In the present study, we demonstrate that the transcription factor ZFP24 drives injury induced Sox9 upregulation. These studies establish ZFP24 as a critical regulator of kidney injury and recovery.

Funding

  • Other NIH Support