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Kidney Week

Abstract: PO0227

Cisplatin-Induced MARCKS Phosphorylation Activates NF-kB Signaling and Contributes to AKI

Session Information

  • AKI Mechanisms - 3
    October 22, 2020 | Location: On-Demand
    Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Gu, Shenwen V., University of California, Davis, Davis, California, United States
  • Liu, Jun, University of California, Davis, Davis, California, United States
  • Jen, Kuang-Yu, University of California, Davis, Davis, California, United States
  • Chen, Ching-Hsien, University of California, Davis, Davis, California, United States
Background

Cisplatin is widely used for cancer treatment but is known to induce nephrotoxicity with severe damage to the proximal tubules, leading to acute kidney injury (AKI). Although a major substrate of protein kinase C, MARCKS, was shown to be induced phosphorylation at Ser 159/163 (phospho-MARCKS) in response to cisplatin, the molecular mechanism underlying increased phospho-MARCKS and its functional consequence in AKI remain to be established. Herein, we investigated how phospho-MARCKS is regulated in proximal tubular cells, and its role in the context of cisplatin exposure.

Methods

The clinical relevance of phospho-MARCKS was first confirmed using immunohistochemistry. Next, we examined the effect of cisplatin exposure on phospho-MARCKS levels in kidney tubular epithelium. The MARCKS-interactome was identified by mass spectrometry. We also used genetic and pharmacological approaches to verify the functionality and molecular mechanism of cisplatin-induced phospho-MARCKS.

Results

In a screen of 75 renal biopsies from patients, we find that strong phospho-MARCKS expression was observed in kidney specimens from patients with acute renal tubular necrosis and was positively correlated. Western blot analyses demonstrate that an elevated abundance of phospho-MARCKS in cisplatin-exposed tubular epithelial cells and this increase appeared to be concentration–dependent. Mechanistically, we show that MARCKS protein directly bound to nuclear factor-kappa-B-activating protein (NKAP). Following cisplatin-induced phosphorylation at ser159 and ser163, the interaction of MARCKS with NKAP was inhibited, contributing to p65 phosphorylation and NF-κB activation. Surprisingly, an elevation of phospho-MARCKS by cisplatin occurred in parallel with upregulation of inflammatory cytokines and markers of nephrotoxicity. Conversely, targeting of MARCKS phosphorylation with the MPS peptide, a novel MARCKS inhibitor, downregulated NF-κB signaling as well as suppressed levels of serum creatinine and blood urea nitrogen in cisplatin-treated mice.

Conclusion

Our results suggest that MARCKS phosphorylation is a novel NF-kB activator in cisplatin-induced proximal tubule damage and also present a proof of concept for the use of MPS peptide as a renal protection agent for AKI.

Funding

  • Other U.S. Government Support