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Kidney Week

Abstract: FR-PO167

mRNA Editing via the Apobec1 Gene Promotes Recovery from AKI

Session Information

  • AKI: Mechanisms - II
    November 03, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Guo, Xiaojia, Yale School of Medicine, New Haven, Connecticut, United States
  • Velazquez, Heino, Yale School of Medicine, New Haven, Connecticut, United States
  • Xu, Leyuan, Yale School of Medicine, New Haven, Connecticut, United States
  • Cheng, Zhongshan, Yale School of Medicine, New Haven, Connecticut, United States
  • Chen, Tian-Min, Yale School of Medicine, New Haven, Connecticut, United States
  • Tian, Yuan, Yale School of Medicine, New Haven, Connecticut, United States
  • Bewersdorf, Joerg, Yale School of Medicine, New Haven, Connecticut, United States
  • Blanc, Valerie, Washington University in St Louis, St Louis, Missouri, United States
  • Davidson, Nicholas, Washington University in St Louis, St Louis, Missouri, United States
  • Safirstein, Robert L., Yale School of Medicine, New Haven, Connecticut, United States
  • Desir, Gary V., Yale School of Medicine, New Haven, Connecticut, United States
Background

Cisplatin (CP) and Ischemia/reperfusion Injury (IRI) induces AKI whereby proximal tubules (PT) undergo necrosis. We now examine the role of Apobec1, which regulates mitochondrial metabolism and cell fate, in the recovery from these forms of AKI.

Methods

Wild type (WT) and Apobec1 knockout (KO) mice received CP 15 mg/kg or were subjected to 20min IRI. Renal function, histology, mRNA, protein, lipids, and RNA sequencing were analyzed and compared. Bone marrow-derived macrophages (BMDM) were isolated from mice treated with or without CP, and their morphology, polarization, and cytokines secretion were analyzed.

Results

Apobec1 KO resulted in more severe CP-AKI as compared to WT (plasma creatinine (pCr): 2.07 mg/dL ± 0.59 vs 0.23 ± 0.09, p < 0.01 in WT) and IRI-AKI (pCr: 1.34 ± 0.22 vs 0.75 ± 0.06, p<0.05 in WT). Inflammatory cytokines were markedly increased in the Apobec1 KO animals after CP. The kidneys of Apobec1 KO showed greater necrosis, neutrophil invasion, activated T cells, elevated markers of injury, as macrophages were unexpectedly reduced. Apobec1 KO BMDM failed to polarize to M1 phenotype in vitro and to home to the kidney in vivo. High resolution microscopy of BMDM isolated from KO AKI animals revealed reduced mitochondria numbers and altered mitochondrial structure as compared to WT AKI animal. Activation of both AMPK α and β was observed in Apobec1 KO AKI, suggesting increased mitochondrial fatty acid oxidation. Mutational and pathway analysis of apobec1 derived mRNA editing differences in WT AKI and Apobec1 KO AKI showed Apobec1 potentially edits genes involved in oxidative stress, inflammation, sterol regulatory element-binding protein signaling, apoptosis and ferroptosis. Overexpression of Apobec1 in PTs in vitro reduced the ferroptosis regulator Acsl4 expression. The Apobec1 KO phenotype in CP-AKI could be rescued by intravenous injection of either BMDMs isolated from WT animals, or of the mitochondrial uncoupler BAM15.

Conclusion

We have identified Apobec1 as a crucial gene regulating the stress response to AKI. The absence of Apobec1 provoked greater oxidant stress and prevented the homing of macrophages to the injured kidney, thus preventing repair and regeneration. Increasing Apobec1 activity could be an effective strategy to reduce or prevent AKI.