Protein Kinase C-? Mediates Kidney Tubular Injury in Cold Storage?Associated Kidney Transplantation

摘要

abstract_textpSignificance StatementUse of cold storage for organ preservation in kidney transplantation is associated with cold ischemia-reperfusion injury that contributes to delayed graft function and affects the long-term outcome of transplanted kidneys. Using rat proximal tubule cells and a mouse model, the authors demonstrated that protein kinase C-? (PKC?), which is implicated in ischemia-reperfusion injury in other organs, is activated in tubular cells during cold storage?associated transplantation and accumulates in mitochondria. There, it mediates phosphorylation of a mitochondrial fission protein, dynamin-related protein 1 (Drp1), at serine 616. Drp1 activation leads to mitochondrial fragmentation, accompanied by mitochondrial damage and kidney tubular cell death. Genetic ablation (in PKC?-knockout mice) or use of a peptide inhibitor of PKC? reduced kidney injury in cold storage?associated transplantation, pointing to PKC? as a promising therapeutic target for kidney transplant. BackgroundKidney injury associated with cold storage is a determinant of delayed graft function and the long-term outcome of transplanted kidneys, but the underlying mechanism remains elusive. We previously reported a role of protein kinase C-? (PKC?) in renal tubular injury during cisplatin nephrotoxicity and albumin-associated kidney injury, but whether PKC? is involved in ischemic or transplantation-associated kidney injury is unknown.MethodsTo investigate PKC??s potential role in injury during cold storage?associated transplantation, we incubated rat kidney proximal tubule cells in University of Wisconsin (UW) solution at 4?C for cold storage, returning them to normal culture medium at 37?C for rewarming. We also stored kidneys from donor mice in cold UW solution for various durations, followed by transplantation into syngeneic recipient mice.ResultsWe observed PKC? activation in both in vitro and in vivo models of cold-storage rewarming or transplantation. In the mouse model, PKC? was activated and accumulated in mitochondria, where it mediated phosphorylation of a mitochondrial fission protein, dynamin-related protein 1 (Drp1), at serine 616. Drp1 activation resulted in mitochondrial fission or fragmentation, accompanied by mitochondrial damage and tubular cell death. Deficiency of PKC? in donor kidney ameliorated Drp1 phosphorylation, mitochondrial damage, tubular cell death, and kidney injury during cold storage?associated transplantation. PKC? deficiency also improved the repair and function of the renal graft as a life-supporting kidney. An inhibitor of PKC?, ?V1-1, protected kidneys against cold storage?associated transplantation injury.ConclusionsThese results indicate that PKC? is a key mediator of mitochondrial damage and renal tubular injury in cold storage?associated transplantation and may be an effective therapeutic target for improving renal transplant outcomes./p/abstract_text