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Kidney Week

Abstract: FR-PO143

Dynamic ATP Changes and Mitochondrial Fragmentation in Podocyte During Ischemia Reperfusion Injury Determines Their Future Structure and Function

Session Information

  • AKI: Mechanisms - II
    November 04, 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

Authors

  • Takahashi, Masahiro, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Yamamoto, Shinya, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Yamamoto, Shigenori, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Okubo, Akihiro, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Yamamoto, Masamichi, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
  • Yanagita, Motoko, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
Background

Previously, we demonstrated that ischemia reperfusion injury (IRI) results in dynamic and detrimental changes of ATP levels in proximal tubules, which are associated with kidney fibrosis in chronic phase. Although proteinuria after ischemia-related events in clinical settings, including kidney transplantation and AKI, has been documented, ATP dynamics in podocytes and the mechanisms underlying podocyte injury during IRI remains elusive.

Methods

GO-ATeam2 mice, which systemically express an ATP biosensor GO-ATeam2, were used for multiphoton microscopy-based intravital ATP imaging. TEM and FIB-SEM were used for microstructural analysis of podocytes. Correlations between ATP recovery in podocytes in acute phase of IRI and foot process effacement and mitochondrial fragmentation of podocytes in chronic phase were assessed. We also analyzed the efficacy of a mitochondrial fission inhibitor Mdivi-1 for structural integrity of podocytes after IRI in vivo, and after ATP-depletion stress in vitro.

Results

ATP levels of podocytes were decreased to the bottom level within 20 minutes during ischemia and recovered in 5 minutes after reperfusion. ATP recovery in podocytes after reperfusion became slower and insufficient after long ischemia. 3D analysis of podocyte mitochondria confirmed mitochondrial fragmentation as early as 30 minutes after reperfusion, when foot process effacement was not evident. Podocytes exhibited prominent foot process effacement and sustained mitochondrial fragmentation in chronic phase of IRI after long ischemia. There was a significant correlation between foot process width and mitochondrial roundness in chronic phase, both of which were inversely correlated with ATP recovery in acute phase. Finally, the administration of Mdivi-1 ameliorated cytoskeletal disarrangement of cultured podocytes after ATP-depletion stress, and foot process effacement in podocytes after IRI in vivo.

Conclusion

ATP depletion and mitochondrial fragmentation in podocytes in acute phase of IRI could contribute to foot process effacement in chronic phase. Our results suggest ischemic stress could induce podocyte injury through ATP depletion and mitochondrial fragmentation, and the latter could be a therapeutic target.

Funding

  • Government Support – Non-U.S.