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

BACKGROUND

Kidney 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.

METHODS

To 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.

RESULTS

We observed PKC activation in both and 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.

CONCLUSIONS

These 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.