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Abstract: SA-PO095

Keap1 Inhibition Ameliorates Cisplatin-Induced Mitochondrial Injury and Oxidative Stress in Renal Proximal Tubule Epithelial Cells Through a Glutathione-Dependent Mechanism

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

Author

  • Chavez, Jose A., Janssen Global Services LLC, Spring House, Pennsylvania, United States

Group or Team Name

  • Cardiovascular & Metabolism, Janssen Research & Development
Background

Mitochondrial impairment is strongly associated with renal function decline. The proximal tubule is typically the initial site of injury where mitochondrial dysfunction leads to disrupted tubular integrity and cellular energetics insufficient to perform critical energy-demanding processes essential for kidney function. Therefore, targets addressing mitochondrial dysfunction in kidney disease provide an opportunity to advance novel therapies. The Keap1-Nrf2-ARE pathway regulates the transcription of various genes that encode cytoprotective and detoxifying enzymes and has pivotal roles in the defense against cellular oxidative stress.

Methods

To examine the impact of Nrf2 activation on mitochondrial function in the setting of oxidative stress, we exposed human primary renal proximal tubule epithelial cells (RPTECs) to cisplatin and used an inhibitor that interrupt the Keap1-Nrf2 protein-protein interaction (PPI).

Results

Cisplatin treatment significantly elevated reactive oxygen species (ROS) production, increased casp3/7 activity, reduced mitochondrial membrane potential, impaired respiration, downregulated genes related to mitochondrial function and decreased nicotinamide adenine dinucleotide (NAD+) levels. These effects were notably suppressed by co-treatment with the small-molecule Keap1−Nrf2 PPI inhibitor. To assess whether the mitochondrial protective effects of Keap1-inhibition in RPTECs are mediated by GSH, an important scavengers of ROS, we treated cells with L-buthionine-(S, R)-sulfoximine (BSO), an inhibitor of GSH synthesis. Notably, BSO treatment negated the protective effects of the Keap1−Nrf2 PPI inhibitor against cisplatin-induced mitochondrial depolarization and apoptosis, while not affecting its ability to induce the transcriptional activation of NRF2 target genes.

Conclusion

Together, our results show that inhibition of the Keap1–Nrf2 PPI activates the antioxidant machinery for ROS scavenging in RPTECs, and that increased levels of intracellular GSH plays an important protective role against cisplatin-induced mitochondrial dysfunction and cellular death.

Funding

  • Commercial Support