Inwardly rectifying potassium channels mediate polymyxin-induced nephrotoxicity

Jing Lu, Mohammad A.K. Azad, Julie L.M. Moreau, Yan Zhu, Xukai Jiang, Mary Tonta, Rachel Lam, Hasini Wickremasinghe, Jinxin Zhao, Jiping Wang, Harold A. Coleman, Luke E. Formosa, Tony Velkov, Helena C. Parkington, Alexander N. Combes, Joseph Rosenbluh, Jian Li

Research output: Contribution to journalArticleResearchpeer-review

6 Citations (Scopus)

Abstract

Polymyxin antibiotics are often used as a last-line defense to treat life-threatening Gram-negative pathogens. However, polymyxin-induced kidney toxicity is a dose-limiting factor of paramount importance and can lead to suboptimal treatment. To elucidate the mechanism and develop effective strategies to overcome polymyxin toxicity, we employed a whole-genome CRISPR screen in human kidney tubular HK-2 cells and identified 86 significant genes that upon knock-out rescued polymyxin-induced toxicity. Specifically, we discovered that knockout of the inwardly rectifying potassium channels Kir4.2 and Kir5.1 (encoded by KCNJ15 and KCNJ16, respectively) rescued polymyxin-induced toxicity in HK-2 cells. Furthermore, we found that polymyxins induced cell depolarization via Kir4.2 and Kir5.1 and a significant cellular uptake of polymyxins was evident. All-atom molecular dynamics simulations revealed that polymyxin B1 spontaneously bound to Kir4.2, thereby increasing opening of the channel, resulting in a potassium influx, and changes of the membrane potential. Consistent with these findings, small molecule inhibitors (BaCl2 and VU0134992) of Kir potassium channels reduced polymyxin-induced toxicity in cell culture and mouse explant kidney tissue. Our findings provide critical mechanistic information that will help attenuate polymyxin-induced nephrotoxicity in patients and facilitate the design of novel, safer polymyxins.

Original languageEnglish
Article number296
Number of pages16
JournalCellular and Molecular Life Sciences
Volume79
Issue number6
DOIs
Publication statusPublished - Jun 2022

Keywords

  • CRISPR/Cas9 screening
  • Kir4.2
  • Kir5.1
  • Polymyxin nephrotoxicity

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